Assigner pins mesh-sdk 76f7c4d, a pull request's head holding 8eafc0c and 77b48a4: the checker refuses a pin to a merge commit on main (issue 774)

# Conflicts:
#	modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/seat_tools_test.go

.gitignore

@@ -1 +1,4 @@
 vendor/
+# A compiled program never enters a commit (issue 1577): `go build .` in a command directory leaves one there.
+modules/*/cmd/*/mesh-*
+!modules/*/cmd/*/mesh-*.go

modules/assignments-readers

@@ -0,0 +1,7 @@
+# The modules of this repository that still read the controller's assignments (mesh-controller.assignments), each with
+# why. mesh-grants' test (TestGrants, "assignments readers") refuses any other module.json that reads them, and an entry
+# here whose module no longer does: the list only shrinks, and it is empty in the first change after the controller's
+# lease is written to a holder that is no controller (novox/hq ADR 0549 §3, §6; issue 774). Each module named here
+# uses the assignments only while the controller holds the lease (buscompose.LeaseHandedAway), placement alone after it.
+mesh-delivery-assigner  unioned with the placement until the lease write (assign.Placed with handedAway); placement alone after
+mesh-grants             unioned with the placement until the lease write (ReadInputs); placement alone after

modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/integration_test.go

@@ -9,6 +9,7 @@ import (
 	"io"
 	"os"
 	"path/filepath"
+	"slices"
 	"strings"
 	"testing"
 	"time"
@@ -17,9 +18,11 @@ import (
 	"github.com/nats-io/nats.go"
 	"github.com/nats-io/nats.go/jetstream"
 
+	stdio "git.novox.be/novox/mesh-sdk/go"
 	"git.novox.be/novox/mesh-sdk/go/announce"
 	"git.novox.be/novox/mesh-sdk/go/asks"
 	"git.novox.be/novox/mesh-sdk/go/catalogue"
+	"git.novox.be/novox/mesh-sdk/go/compose/judge"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 	"git.novox.be/novox/mesh-sdk/go/process"
 	"git.novox.be/novox/mesh-sdk/go/provider"
@@ -69,7 +72,11 @@ func startBed(t *testing.T, leaveOut string) *bed {
 		if name == leaveOut {
 			continue
 		}
-		kv, err := js.CreateKeyValue(ctx, jetstream.KeyValueConfig{Bucket: name, History: 5})
+		cfg := jetstream.KeyValueConfig{Bucket: name, History: 5}
+		if name == delivery.PlacementPulsesBucket {
+			cfg.History, cfg.LimitMarkerTTL = 1, time.Minute // a time to live per key, as the controller makes it (key-ttl)
+		}
+		kv, err := js.CreateKeyValue(ctx, cfg)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -128,9 +135,7 @@ func (b *bed) startStoppable(t *testing.T) (<-chan error, func()) {
 
 // 1297/B2b: started whole on its credential, the assigner says on the bus every state its manifest declares, each readable,
 // having opened every bucket it names. The states are read from module.json, so a state added there is expected here too.
-func TestTheAssignerStartsAndSaysWhatItKeeps(t *testing.T) {
-	b := startBed(t, "")
-	done := b.start(t)
+func saysWhatItKeeps(t *testing.T, b *bed, done <-chan error) {
 	events, err := b.js.Stream(b.ctx, "EVENTS")
 	if err != nil {
 		t.Fatal(err)
@@ -172,6 +177,9 @@ func TestTheAssignerStartsAndSaysWhatItKeeps(t *testing.T) {
 // 1297/B2b: a bucket it reads that the bus does not hold stops the start, naming the bucket.
 func TestTheAssignerDoesNotStartWithoutABucketItReads(t *testing.T) {
 	for _, missing := range readBuckets {
+		if missing == delivery.PlacementBucket || sourceOfGrants(missing) {
+			continue // it starts without it, below (the grants' source: main_test.go)
+		}
 		b := startBed(t, missing)
 		select {
 		case err := <-b.start(t):
@@ -218,6 +226,34 @@ func TestTheAssignerDoesNotStartWithoutABucketItReads(t *testing.T) {
 			t.Fatal("the put was not taken further once its bucket was made")
 		}
 	}
+
+	// Without the seat's placement state it starts all the same, and once the bucket is made (the controller makes
+	// it from the manifest) it is read with no restart: a module only the placement names is
+	// said as placed by one source only.
+	pb := startBed(t, delivery.PlacementBucket)
+	pdone := pb.start(t)
+	select {
+	case err := <-pdone:
+		t.Fatalf("without %s the assigner stopped: %v", delivery.PlacementBucket, err)
+	case <-time.After(2 * time.Second):
+	}
+	placement, err := pb.js.CreateKeyValue(pb.ctx, jetstream.KeyValueConfig{Bucket: delivery.PlacementBucket, History: 5})
+	if err != nil {
+		t.Fatal(err)
+	}
+	pl, _ := delivery.EncodePlacement(delivery.Placement{Node: "n1", Modules: []delivery.PlacedModule{{Module: "web"}}})
+	plkey, _ := delivery.PlacementKey("n1")
+	if _, err := placement.Put(pb.ctx, plkey, pl); err != nil {
+		t.Fatal(err)
+	}
+	for deadline := time.Now().Add(15 * time.Second); ; time.Sleep(200 * time.Millisecond) {
+		if c, ok := pb.conditionsSaid(t)[delivery.AssignerModule+".placement.n1.web"]; ok && c.State == asks.StateRaised {
+			break
+		}
+		if time.Now().After(deadline) {
+			t.Fatal("the placement state made after the start was not read")
+		}
+	}
 }
 
 // putJSON writes a value into one of the bed's buckets.
@@ -406,6 +442,32 @@ func TestWantsAreWrittenAndNoDifferenceIs(t *testing.T) {
 	if !cleared {
 		t.Errorf("the condition of web on neither list on g14 was not cleared once g14 got its want")
 	}
+
+	// Issue 1126 (ADR 0547 §2): the catalogue's placement reaches the indexer's state naming web on every node the
+	// assignments name it on. Each node then composes its own: its want names the build alone (Self, no composition), and
+	// its own want says it composes its own, which the node agent reads (mesh-host's TestNats...ComposesAndAppliesItsOwn).
+	for _, node := range []string{"ace", "g14", "shanks"} {
+		pl, err := delivery.EncodePlacement(delivery.Placement{Node: node, Modules: []delivery.PlacedModule{{Module: "web"}}})
+		if err != nil {
+			t.Fatal(err)
+		}
+		pkey, _ := delivery.PlacementKey(node)
+		b.putJSON(t, delivery.PlacementBucket, pkey, pl)
+	}
+	if w := b.wantNow(t, "ace", "web", "ace's want once placed: the build alone, composed by the node", func(w delivery.Want) bool { return w.Self }); w.Composed != "" || w.FP != fNew {
+		t.Errorf("ace's want once placed = %+v", w)
+	}
+	nkey, _ := delivery.WantNodeKey("ace")
+	var self bool
+	for deadline := time.Now().Add(10 * time.Second); time.Now().Before(deadline) && !self; time.Sleep(100 * time.Millisecond) {
+		if e, err := b.buckets[delivery.AssignerWantsBucket].Get(b.ctx, nkey); err == nil {
+			nw, err := delivery.DecodeNodeWant(e.Value())
+			self = err == nil && nw.Self
+		}
+	}
+	if !self {
+		t.Error("ace's own want does not say it composes its own once placed")
+	}
 }
 
 // 1297/B9 (the assigner's half, ADR 0528 clause 6): started whole, the assigner holds a fingerprint whose health check
@@ -943,3 +1005,196 @@ func TestAHoldWrittenAgainAfterALiftAndARestartIsAskedAgain(t *testing.T) {
 		}
 	}
 }
+
+// bedStore is the runtime's states over the bed's buckets, as the seat's verbs read and write them: the assigner's own by
+// their local names, another module's `<module>.<state>`.
+type bedStore struct{ b *bed }
+
+func (s bedStore) kv(state string) jetstream.KeyValue {
+	if strings.Contains(state, ".") {
+		return s.b.buckets[strings.Replace(state, ".", "_", 1)]
+	}
+	return s.b.buckets[delivery.AssignerModule+"_"+state]
+}
+
+func (s bedStore) get(state, key string) ([]byte, uint64, bool, error) {
+	e, err := s.kv(state).Get(s.b.ctx, key)
+	if err != nil {
+		return nil, 0, false, nil
+	}
+	return e.Value(), e.Revision(), true, nil
+}
+
+func (s bedStore) put(state, key string, value []byte) error {
+	_, err := s.kv(state).Put(s.b.ctx, key, value)
+	return err
+}
+
+func (s bedStore) keys(state string) ([]string, error) {
+	keys, err := s.kv(state).Keys(s.b.ctx)
+	if err != nil && strings.Contains(err.Error(), "no keys") {
+		return nil, nil
+	}
+	return keys, err
+}
+
+func (s bedStore) del(state, key string) error { return s.kv(state).Delete(s.b.ctx, key) }
+
+func (s bedStore) history(string, string) ([]stdio.StateRevision, error) { return nil, nil }
+
+// 1126 (ADR 0567 §2-§6), the seat mesh-placement whole on the bus: a proposal moving web from the anchor to the laptop is
+// proposed through the verb, the assigner finds both nodes must answer, they answer the same in their haves, the
+// operator is asked and approves, and each key is written at a new revision while placement-changed is heard on the
+// assigner's stream naming both nodes. A second proposal laid over the old revision of a key moved since is laid again,
+// and declined, writes nothing and is withdrawn.
+func TestAProposalIsAnsweredApprovedAndWritten(t *testing.T) {
+	b := startBed(t, "")
+	if _, err := b.js.CreateStream(b.ctx, jetstream.StreamConfig{Name: "MOD_" + delivery.AssignerModule + "_placement",
+		Subjects: []string{process.ModuleStreamSubject(delivery.AssignerModule, ">")}}); err != nil {
+		t.Fatal(err)
+	}
+	heard := make(chan delivery.PlacementEvent, 16)
+	nc, err := nats.Connect(b.srv.ClientURL())
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(nc.Close)
+	if _, err := nc.Subscribe(process.ModuleStreamSubject(delivery.AssignerModule, delivery.PlacementChangedEvent), func(m *nats.Msg) {
+		var e delivery.PlacementEvent
+		if json.Unmarshal(m.Data, &e) == nil {
+			heard <- e
+		}
+	}); err != nil {
+		t.Fatal(err)
+	}
+	for _, node := range []string{"anchor", "laptop"} {
+		rec, _ := delivery.EncodeHaveNode(delivery.HaveNode{Record: &delivery.NodeRecord{Node: node}})
+		b.putJSON(t, delivery.HaveBucket, node+".node", rec)
+	}
+	b.putJSON(t, delivery.ModulesBucket, "web", []byte(`{"v":1}`))
+	b.putJSON(t, delivery.ModulesBucket, "shell", []byte(`{"v":1}`))
+	place := func(node string, modules ...string) uint64 {
+		p := delivery.Placement{Node: node, Modules: []delivery.PlacedModule{}}
+		for _, m := range modules {
+			p.Modules = append(p.Modules, delivery.PlacedModule{Module: m})
+		}
+		raw, _ := delivery.EncodePlacement(p)
+		key, _ := delivery.PlacementKey(node)
+		rev, err := b.buckets[delivery.PlacementBucket].Put(b.ctx, key, raw)
+		if err != nil {
+			t.Fatal(err)
+		}
+		return rev
+	}
+	anchorRev, laptopRev := place("anchor", "web"), place("laptop", "shell")
+	bound := judge.AnswerBound
+	t.Cleanup(func() { judge.AnswerBound = bound })
+	judge.AnswerBound = 2 * time.Second
+	saysWhatItKeeps(t, b, b.start(t))
+	verbs := newSeatTools(bedStore{b}, func(string, any) (json.RawMessage, error) { return json.RawMessage(`{"ok":true}`), nil })
+	propose := func() delivery.PlacementProposal {
+		t.Helper()
+		got, err := verbs.doPropose(map[string]any{"why": "move web", "changes": `[{"op":"take-off","node":"anchor","module":"web"},` +
+			`{"op":"place","node":"laptop","module":"web"}]`}, "operator@laptop")
+		if err != nil {
+			t.Fatal(err)
+		}
+		return got.(proposed).Proposal
+	}
+	proposalNow := func(id, what string, ok func(delivery.PlacementProposal) bool) delivery.PlacementProposal {
+		t.Helper()
+		var last delivery.PlacementProposal
+		for deadline := time.Now().Add(15 * time.Second); time.Now().Before(deadline); time.Sleep(50 * time.Millisecond) {
+			if e, err := b.buckets[delivery.PlacementProposalsBucket].Get(b.ctx, id); err == nil {
+				if p, err := delivery.DecodePlacementProposal(e.Value()); err == nil {
+					if last = p; ok(p) {
+						return p
+					}
+				}
+			}
+		}
+		t.Fatalf("the proposal %s never was %s: %+v", id, what, last)
+		return last
+	}
+	answerAll := func(p delivery.PlacementProposal) {
+		t.Helper()
+		for _, node := range p.Must {
+			key, _ := delivery.PlacementCandidateKey(p.ID, node)
+			e, err := b.buckets[delivery.PlacementCandidatesBucket].Get(b.ctx, key)
+			if err != nil {
+				t.Fatalf("no candidate %s: %v", key, err)
+			}
+			have, _ := delivery.EncodeHaveNode(delivery.HaveNode{Record: &delivery.NodeRecord{Node: node}, Candidates: map[string]delivery.CandidateAnswer{
+				p.ID: {Proposal: p.ID, Revision: e.Revision(), Verdict: delivery.CandidateSame, Same: []string{"node"}}}})
+			b.putJSON(t, delivery.HaveBucket, node+".node", have)
+		}
+	}
+
+	p := propose()
+	p = proposalNow(p.ID, "told who must answer", func(p delivery.PlacementProposal) bool { return len(p.Must) > 0 })
+	if !slices.Equal(p.Must, []string{"anchor", "laptop"}) {
+		t.Fatalf("must answer = %v, want both nodes", p.Must)
+	}
+	answerAll(p)
+	p = proposalNow(p.ID, "asked", func(p delivery.PlacementProposal) bool { return p.State == delivery.ProposalAsked })
+	akey, _ := delivery.PlacementAskKey(p.ID)
+	b.answer(t, akey, assign.OptionYes)
+	select {
+	case e := <-heard:
+		if e.Proposal.ID != p.ID || len(e.Nodes) != 2 || e.Nodes[0].Before != anchorRev || e.Nodes[1].Before != laptopRev ||
+			e.Nodes[0].After <= anchorRev || e.Warrant == nil || !slices.Equal(e.Nodes[0].Removed, []string{"web"}) {
+			t.Errorf("placement-changed = %+v", e)
+		}
+	case <-time.After(15 * time.Second):
+		t.Fatal("no placement-changed heard")
+	}
+	for node, want := range map[string][]string{"anchor": {}, "laptop": {"shell", "web"}} {
+		key, _ := delivery.PlacementKey(node)
+		e, err := b.buckets[delivery.PlacementBucket].Get(b.ctx, key)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if got, err := delivery.DecodePlacement(e.Value()); err != nil || !slices.Equal(got.Assigned(), want) {
+			t.Errorf("%s = %v, %v, want %v", node, got.Assigned(), err, want)
+		}
+	}
+	if b.hasKey(delivery.PlacementProposalsBucket, p.ID) {
+		t.Error("an applied proposal stays in the state")
+	}
+
+	// A proposal whose key moves before its warrant is laid again; then declined, it writes nothing and ends.
+	q, err := verbs.doPropose(map[string]any{"why": "back", "changes": `[{"op":"take-off","node":"laptop","module":"web"}]`}, "op")
+	if err != nil {
+		t.Fatal(err)
+	}
+	moved := q.(proposed).Proposal
+	place("laptop", "shell", "web") // another writer moved the key
+	relaid := proposalNow(moved.ID, "laid again", func(p delivery.PlacementProposal) bool {
+		return strings.Contains(p.Words, "laid again") && len(p.Must) > 0
+	})
+	answerAll(relaid)
+	proposalNow(moved.ID, "asked", func(p delivery.PlacementProposal) bool { return p.State == delivery.ProposalAsked })
+	akey, _ = delivery.PlacementAskKey(moved.ID)
+	b.answer(t, akey, assign.OptionNo)
+	for deadline := time.Now().Add(15 * time.Second); b.hasKey(delivery.PlacementProposalsBucket, moved.ID); time.Sleep(50 * time.Millisecond) {
+		if time.Now().After(deadline) {
+			t.Fatal("a declined proposal was not ended")
+		}
+	}
+	key, _ := delivery.PlacementKey("laptop")
+	if e, _ := b.buckets[delivery.PlacementBucket].Get(b.ctx, key); e == nil || !strings.Contains(string(e.Value()), "web") {
+		t.Error("a declined proposal wrote its key")
+	}
+
+	// ADR 0567 §4: a node that does not answer fails the verdict once its pulse key's time to live ends, heard on the bus
+	// with no timer of the assigner's, naming it.
+	q, err = verbs.doPropose(map[string]any{"why": "again", "changes": `[{"op":"take-off","node":"laptop","module":"web"}]`}, "op")
+	if err != nil {
+		t.Fatal(err)
+	}
+	silent := q.(proposed).Proposal
+	failed := proposalNow(silent.ID, "failed for a silent node", func(p delivery.PlacementProposal) bool { return p.State == delivery.ProposalFailed })
+	if failed.Verdict == nil || !strings.Contains(strings.Join(failed.Verdict.Fails, "; "), "laptop (offline) did not answer") {
+		t.Errorf("the silent node's verdict = %+v", failed.Verdict)
+	}
+}

modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/main.go

@@ -14,7 +14,7 @@ import (
 	"log"
 	"os"
 	"os/signal"
-	"strings"
+	"slices"
 	"syscall"
 	"time"
 
@@ -23,6 +23,7 @@ import (
 
 	"git.novox.be/novox/mesh-sdk/go/announce"
 	"git.novox.be/novox/mesh-sdk/go/asks"
+	"git.novox.be/novox/mesh-sdk/go/buscompose"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 	"git.novox.be/novox/mesh-sdk/go/delivery/buildrun"
 	"git.novox.be/novox/mesh-sdk/go/process"
@@ -30,7 +31,7 @@ import (
 )
 
 func main() {
-	if os.Getenv("MESH_BROKER_FILE") == "" {
+	if os.Getenv(process.BrokerFileEnv) == "" {
 		// Started by the tool runner, with no credential of its own: the put's tools (ADR 0546), served through the runtime,
 		// since a process never serves (ADR 0436). The process the manifest runs names its credential.
 		if err := serveTools(); err != nil {
@@ -50,9 +51,12 @@ func main() {
 // readBuckets are the buckets of other parts the assigner reads, each named in its manifest's reads (the manifest test
 // holds the two lists equal), so the controller's broker grants exactly these.
 var readBuckets = []string{
+	buscompose.ResolvedBucket,
 	provider.AssignmentsBucket,
 	delivery.BuildsBucket,
 	delivery.ControllerGrantsBucket,
+	delivery.PartGrantsBucket,
+	buscompose.LeaseBucket,
 	delivery.ControllerComposedBucket,
 	delivery.AnswersBucket,
 	delivery.BuilderBuildsBucket,
@@ -68,14 +72,27 @@ var readBuckets = []string{
 // their steps in its steps state (novox/hq ADR 0482 clause 4).
 const goBuildModule = "mesh-build-go"
 
-// ownBuckets are the assigner's own states, as its manifest declares them.
+// ownBuckets are the assigner's own states, as its manifest declares them: the seat mesh-placement's three among them
+// (ADR 0567 §1), named after the assigner as every module state is.
 var ownBuckets = []string{delivery.AssignerAsksBucket, delivery.AssignerCompositionsBucket, delivery.AssignerDifferencesBucket,
-	delivery.AssignerPutsBucket, delivery.AssignerWantsBucket}
+	delivery.AssignerPutsBucket, delivery.AssignerWantsBucket, delivery.PlacementBucket, delivery.PlacementProposalsBucket,
+	delivery.PlacementCandidatesBucket, delivery.PlacementPulsesBucket}
+
+// seatBuckets are the seat's states, new with it: until the controller has made them from the manifest and the bus grants
+// them, the assigner starts without them and binds each once the bus says it was created (issue 1790's kind).
+var seatBuckets = []string{delivery.PlacementBucket, delivery.PlacementProposalsBucket, delivery.PlacementCandidatesBucket,
+	delivery.PlacementPulsesBucket}
 
 // keptStates is what the assigner keeps and who may read it (ADR 0495 §2-§3): its wants by the watchman and the view
 // (and the node agent from release 6), its differences by the view, its compositions by the checker, its asks by the view
-// and the teller, its puts by whoever follows one (ADR 0546).
+// and the teller, its puts by whoever follows one (ADR 0546), and the seat mesh-placement's placement, proposals and
+// candidates by the node agents, the grants part, mesh-config and the view (ADR 0567 §9), and its placement by
+// the builder, the checker and the indexer, through mesh-sdk's toolchain gate (issue 774, ADR 0549 §3).
 var keptStates = []announce.State{
+	{Name: delivery.PlacementState, Readable: true},
+	{Name: delivery.PlacementProposalsState, Readable: true},
+	{Name: delivery.PlacementCandidatesState, Readable: true},
+	{Name: delivery.PlacementPulsesState, Readable: true},
 	{Name: "asks", Readable: true},
 	{Name: "compositions", Readable: true},
 	{Name: "differences", Readable: true},
@@ -92,12 +109,49 @@ type buckets map[string]jetstream.KeyValue
 // without it and takes no put further until it starts again (ADR 0546).
 func open(ctx context.Context, js process.BucketOpener, logf func(string, ...any)) (buckets, error) {
 	out := buckets{}
+	// The controller's lease first (ADR 0549 §5, ADR 0561 §3): once it is handed away the seat's placement alone names
+	// where modules run, and the controller's assignments are no bucket the assigner needs. Not granted or not there, the
+	// controller holds it, as before.
+	away, why := false, ""
+	if kv, err := js.KeyValue(ctx, buscompose.LeaseBucket); err != nil {
+		logf("the bucket %s cannot be opened (%v): the controller is taken to hold its lease, so the assignments are read beside the placement", buscompose.LeaseBucket, err)
+	} else {
+		out[buscompose.LeaseBucket] = kv
+		e, gerr := kv.Get(ctx, buscompose.ControllerLeaseKey)
+		var raw []byte
+		if gerr == nil {
+			raw = e.Value()
+		}
+		if errors.Is(gerr, jetstream.ErrKeyNotFound) {
+			gerr = nil
+		}
+		away, why = buscompose.LeaseHandedAway(raw, raw != nil, gerr)
+	}
 	for _, name := range append(append([]string{}, readBuckets...), ownBuckets...) {
+		if name == buscompose.LeaseBucket {
+			continue
+		}
 		kv, err := js.KeyValue(ctx, name)
+		if name == provider.AssignmentsBucket && err != nil && away {
+			logf("the bucket %s cannot be opened (%v), and none is needed: %s, so the seat's placement alone is read", name, err, why)
+			continue
+		}
 		if name == delivery.AssignerPutsBucket && err != nil {
 			logf("the bucket %s cannot be opened (%v): no put is taken further until the assigner starts again", name, err)
 			continue
 		}
+		if slices.Contains(seatBuckets, name) && err != nil {
+			// The seat's states come in the same delivery as this assigner (ADR 0567 §1): without placement the controller's
+			// assignments alone name where modules run, as before any placement was written (ADR 0549 §5).
+			logf("the bucket %s cannot be opened (%v): it is bound once the bus says it was made", name, err)
+			continue
+		}
+		if sourceOfGrants(name) && err != nil {
+			// The grants part's grants and the controller's lease choose where grants are read from (issue 774): without
+			// them the controller's grants are read, as before the lease is handed away.
+			logf("the bucket %s cannot be opened (%v): the controller's grants are read until the assigner starts again", name, err)
+			continue
+		}
 		if err != nil {
 			return nil, process.EssentialErr("assigner", name, "write a want from the whole mesh", err)
 		}
@@ -106,36 +160,24 @@ func open(ctx context.Context, js process.BucketOpener, logf func(string, ...any
 	return out, nil
 }
 
+// sourceOfGrants says the bucket is one of the two that choose the grants' source, the grants part's grants and the
+// controller's lease: neither stops the assigner when it is not there (delivery.GrantSource).
+func sourceOfGrants(name string) bool {
+	return name == delivery.PartGrantsBucket || name == buscompose.LeaseBucket
+}
+
 // run is the program: it returns when ctx ends or the bus cannot be used.
 func run(ctx context.Context, getenv func(string) string, logOut io.Writer) error {
 	logger := log.New(logOut, "mesh-delivery-assigner: ", log.LstdFlags)
-	path := strings.TrimSpace(getenv("MESH_BROKER_FILE"))
-	if path == "" {
-		return errors.New("MESH_BROKER_FILE is not set, so there is no credential to read the bus with")
-	}
-	account, err := process.ReadAccount(path)
+	account, err := process.ReadBrokerAccount(getenv)
 	if err != nil {
 		return err
 	}
-	opts := []nats.Option{
-		nats.Name(account.Node + "." + account.Module),
-		nats.UserInfo(account.User, account.Password),
-		nats.CustomInboxPrefix(account.InboxPrefix()),
-		nats.MaxReconnects(-1),
-		nats.RetryOnFailedConnect(true),
-	}
-	if strings.TrimSpace(account.Fingerprint) != "" {
-		opts = append(opts, nats.Secure(process.PinnedToFingerprint(account.Fingerprint)))
-	}
-	conn, err := nats.Connect(account.URL, opts...)
+	conn, js, err := account.Dial()
 	if err != nil {
-		return fmt.Errorf("connecting to the bus: %w", err)
+		return err
 	}
 	defer conn.Close()
-	js, err := jetstream.New(conn)
-	if err != nil {
-		return err
-	}
 	kvs, err := open(ctx, js, logger.Printf)
 	if err != nil {
 		return err
@@ -150,10 +192,14 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 	if err := said.Keeps(keptStates...); err != nil {
 		logger.Printf("what the assigner keeps could not be said on the bus, so its readers are not granted until it is: %v", err)
 	}
+	thisNode = account.Node
 	logger.Printf("started on the account %s, reading %d buckets", account.User, len(kvs))
-	return follow(ctx, js, kvs, sayVia(ctx, js), emitting{said}, logger)
+	return follow(ctx, js, conn, kvs, sayVia(ctx, js), emitting{said}, logger)
 }
 
+// thisNode is the node this process runs on, as its credential names it: said with each of the seat's events.
+var thisNode string
+
 // emitting is the process connection as the puts' caller: its calls, and its events with no options.
 type emitting struct{ *process.Conn }
 
@@ -162,13 +208,20 @@ func (e emitting) Emit(eventType string, body any) error { return e.Conn.Emit(ev
 // watched are the buckets whose every value a pass reads; the manifests are read by digest when a pass needs one, and
 // watched only for keys, so a manifest that arrives wakes a composition that waits for it.
 var watched = []string{
+	buscompose.ResolvedBucket,
 	provider.AssignmentsBucket,
 	delivery.ControllerGrantsBucket,
+	delivery.PartGrantsBucket,
+	buscompose.LeaseBucket,
 	delivery.ControllerComposedBucket,
 	delivery.AnswersBucket,
 	delivery.BuilderBuildsBucket,
 	delivery.CandidatesBucket,
 	delivery.ModulesBucket,
+	delivery.PlacementBucket,
+	delivery.PlacementProposalsBucket,
+	delivery.PlacementCandidatesBucket,
+	delivery.PlacementPulsesBucket,
 	delivery.PresenceBucket,
 	delivery.HaveBucket,
 	delivery.AssignerAsksBucket,
@@ -179,7 +232,7 @@ var watched = []string{
 
 // follow watches every bucket a pass reads and makes a pass at start, once every watch handed what stands, and after
 // each change; changes that come during a pass make one more. It returns when ctx ends or a watch ends.
-func follow(ctx context.Context, js jetstream.JetStream, kvs buckets, say func(asks.Condition) error, bus caller, logger *log.Logger) error {
+func follow(ctx context.Context, js jetstream.JetStream, nc process.Subscriber, kvs buckets, say func(asks.Condition) error, bus caller, logger *log.Logger) error {
 	w := newWorld()
 	dirty := make(chan struct{}, 1)
 	wake := func() {
@@ -223,7 +276,13 @@ func follow(ctx context.Context, js jetstream.JetStream, kvs buckets, say func(a
 					if e.Operation() == jetstream.KeyValuePut {
 						value = e.Value()
 					}
-					w.put(name, e.Key(), value)
+					before := w.grantsBucket()
+					w.putEntry(name, e.Key(), value, e.Revision(), e.Created())
+					if name == buscompose.LeaseBucket && w.grantsBucket() == before {
+						// The controller renews its lease every few seconds: only a change of where grants are read from
+						// makes a pass (delivery.GrantSource).
+						continue
+					}
 					wake()
 				}
 			}
@@ -263,7 +322,12 @@ func follow(ctx context.Context, js jetstream.JetStream, kvs buckets, say func(a
 		}
 		logger.Printf("the bucket %s is open: puts are taken further", delivery.AssignerPutsBucket)
 	}
+	started := 0
 	for _, name := range watched {
+		if kvs[name] == nil && (slices.Contains(seatBuckets, name) || sourceOfGrants(name) || name == provider.AssignmentsBucket) {
+			continue // not on the bus at this start (open said so)
+		}
+		started++
 		var opts []jetstream.WatchOpt
 		if name == delivery.HaveBucket {
 			opts = append(opts, jetstream.IncludeHistory()) // what each node ran healthy before, for a set-back
@@ -275,7 +339,37 @@ func follow(ctx context.Context, js jetstream.JetStream, kvs buckets, say func(a
 	if err := watch(delivery.ManifestsBucket, jetstream.MetaOnly()); err != nil {
 		return err
 	}
-	for range len(watched) + 1 {
+	// The seat's states arrive with the same delivery as this assigner (ADR 0567 §1): one not on the bus at this start is
+	// bound once the bus says it was created, and watched from then on, with no restart (issue 1790's kind). Until then the
+	// controller's assignments alone name where modules run (ADR 0549 §5).
+	type appeared struct {
+		name string
+		kv   jetstream.KeyValue
+	}
+	placementAppeared := make(chan appeared, len(seatBuckets)+2)
+	for _, name := range seatBuckets {
+		if kvs[name] == nil && js != nil {
+			process.AwaitBucket(ctx, js, nc, name, "the seat mesh-placement waits for it",
+				logger.Printf).Ready(func(kv jetstream.KeyValue) { placementAppeared <- appeared{name, kv} })
+		}
+	}
+	// And the two that choose where grants are read from, with the same delivery as the grants part that writes one.
+	for _, name := range []string{delivery.PartGrantsBucket, buscompose.LeaseBucket} {
+		if kvs[name] == nil && js != nil {
+			name := name
+			process.AwaitBucket(ctx, js, nc, name, "the controller's grants are read",
+				logger.Printf).Ready(func(kv jetstream.KeyValue) { placementAppeared <- appeared{name, kv} })
+		}
+	}
+	takePlacement := func(a appeared) error {
+		if kvs[a.name] != nil {
+			return nil // bound already, by the other of its two events
+		}
+		kvs[a.name] = a.kv
+		logger.Printf("the bucket %s is open and watched", a.name)
+		return watch(a.name)
+	}
+	for range started + 1 {
 		select {
 		case <-ctx.Done():
 			return nil
@@ -289,6 +383,12 @@ func follow(ctx context.Context, js jetstream.JetStream, kvs buckets, say func(a
 	if bus != nil && kvs[delivery.AssignerPutsBucket] != nil {
 		p.acts = newPutActs(bus, wake, logger.Printf)
 	}
+	if bus != nil {
+		p.seat = newSeatActs(bus, wake, logger.Printf)
+	}
+	if js != nil {
+		p.publish = streamPublisher(ctx, js, thisNode)
+	}
 	wake()
 	for {
 		select {
@@ -297,8 +397,29 @@ func follow(ctx context.Context, js jetstream.JetStream, kvs buckets, say func(a
 		case err := <-errs:
 			return err
 		case <-settled:
+		case kv := <-placementAppeared:
+			if err := takePlacement(kv); err != nil {
+				return err
+			}
 		case <-dirty:
 			reopenPuts(p)
+			// The grants part makes the seat's buckets in the pass that seals the list granting them, so their creation can
+			// be said before this credential may hear it: every pass, itself started by a watched change, binds each one the
+			// bus now holds, and says the seat waits while one is missing.
+			var unbound []string
+			for _, name := range seatBuckets {
+				if kvs[name] != nil || js == nil {
+					continue
+				}
+				if kv, err := js.KeyValue(ctx, name); err == nil {
+					if err := takePlacement(appeared{name, kv}); err != nil {
+						return err
+					}
+					continue
+				}
+				unbound = append(unbound, name)
+			}
+			p.sayWaits(unbound)
 			p.pass(ctx)
 		}
 	}

modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/main_test.go

@@ -17,13 +17,19 @@ import (
 	"github.com/nats-io/nats.go/jetstream"
 
 	"git.novox.be/novox/mesh-sdk/go/asks"
+	"git.novox.be/novox/mesh-sdk/go/buscompose"
 	"git.novox.be/novox/mesh-sdk/go/catalogue"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
+	"git.novox.be/novox/mesh-sdk/go/provider"
 )
 
 // 1297/B2a: the buckets the program opens are exactly the manifest's reads and states, as the broker names them
 // (`<module>.<state>` read as the bucket `<module>_<state>`), so it is granted what it reads and reads nothing else.
 func TestOpensWhatItsManifestNames(t *testing.T) {
+	// 1297/B2a: without a credential the program does not start, and says why.
+	if err := run(context.Background(), func(string) string { return "" }, io.Discard); err == nil || !strings.Contains(err.Error(), "MESH_BROKER_FILE") {
+		t.Errorf("run without a credential = %v", err)
+	}
 	raw, err := os.ReadFile(filepath.Join("..", "..", "module.json"))
 	if err != nil {
 		t.Fatal(err)
@@ -58,20 +64,30 @@ func TestOpensWhatItsManifestNames(t *testing.T) {
 	}
 	// ADR 0546: whatever keeps the puts' bucket from opening (not there, not granted, no answer in time), the assigner opens
 	// the rest and starts, writing wants; any other bucket it cannot open stops the start, named.
+	// Issue 774 (ADR 0549 §5): the controller's lease not granted, the assigner starts taking it as the controller's; the
+	// assignments refused while the controller holds it stop the start, and once it is handed away they are not needed.
+	handed := []byte(`{"handed-to":"the operator's hand-over","handed-by":"person.jochen"}`)
 	for _, c := range []struct {
 		missing string
 		err     error
 		starts  bool
+		lease   []byte
+		said    string
 	}{
-		{delivery.AssignerPutsBucket, jetstream.ErrBucketNotFound, true},
-		{delivery.AssignerPutsBucket, errors.New("nats: permissions violation for subscription to \"$JS.API.STREAM.INFO.KV_mesh-delivery-assigner_puts\""), true},
-		{delivery.AssignerPutsBucket, context.DeadlineExceeded, true},
-		{delivery.AssignerWantsBucket, errors.New("nats: permissions violation"), false},
+		{delivery.AssignerPutsBucket, jetstream.ErrBucketNotFound, true, nil, "no put is taken further"},
+		{delivery.AssignerPutsBucket, errors.New("nats: permissions violation for subscription to \"$JS.API.STREAM.INFO.KV_mesh-delivery-assigner_puts\""), true, nil, "no put is taken further"},
+		{delivery.AssignerPutsBucket, context.DeadlineExceeded, true, nil, "no put is taken further"},
+		{delivery.AssignerWantsBucket, errors.New("nats: permissions violation"), false, nil, ""},
+		// Issue 774: the grants part's grants and the controller's lease choose the grants' source; neither stops the start.
+		{delivery.PartGrantsBucket, jetstream.ErrBucketNotFound, true, nil, "the controller's grants are read"},
+		{buscompose.LeaseBucket, errors.New("nats: permissions violation"), true, nil, "taken to hold its lease"},
+		{provider.AssignmentsBucket, errors.New("nats: permissions violation"), false, []byte(`{"instance":"novox/1"}`), ""},
+		{provider.AssignmentsBucket, errors.New("nats: permissions violation"), true, handed, "the seat's placement alone is read"},
 	} {
 		var logged string
-		kvs, err := open(context.Background(), refusingJS{missing: c.missing, err: c.err}, func(f string, a ...any) { logged = fmt.Sprintf(f, a...) })
+		kvs, err := open(context.Background(), refusingJS{missing: c.missing, err: c.err, lease: c.lease}, func(f string, a ...any) { logged += fmt.Sprintf(f, a...) })
 		switch {
-		case c.starts && (err != nil || kvs[c.missing] != nil || len(kvs) != len(readBuckets)+len(ownBuckets)-1 || !strings.Contains(logged, "no put is taken further")):
+		case c.starts && (err != nil || kvs[c.missing] != nil || len(kvs) != len(readBuckets)+len(ownBuckets)-1 || !strings.Contains(logged, c.said)):
 			t.Errorf("%s refused with %v: the start answered %v, %d buckets, logged %q", c.missing, c.err, err, len(kvs), logged)
 		case !c.starts && (err == nil || !strings.Contains(err.Error(), "grant of "+c.missing)): // 1945: named with its grant
 			t.Errorf("%s refused with %v: the start answered %v", c.missing, c.err, err)
@@ -94,7 +110,7 @@ func TestOpensWhatItsManifestNames(t *testing.T) {
 	kvs[delivery.ControllerComposedBucket].(*watchKV).entries = []kvEntry{{key: ckey, value: cd}}
 	kvs[delivery.AssignerPutsBucket].(*watchKV).closed = true
 	kvs[delivery.AssignerWantsBucket].(*watchKV).wrote = wrote
-	go follow(ctx, nil, kvs, func(asks.Condition) error { return nil }, nil, log.New(io.Discard, "", 0))
+	go follow(ctx, nil, nil, kvs, func(asks.Condition) error { return nil }, nil, log.New(io.Discard, "", 0))
 	select {
 	case key := <-wrote:
 		if key != "want.ace.node" {
@@ -105,26 +121,23 @@ func TestOpensWhatItsManifestNames(t *testing.T) {
 	}
 }
 
-// 1297/B2a: without a credential the program does not start, and says why.
-func TestNoCredential(t *testing.T) {
-	err := run(context.Background(), func(string) string { return "" }, io.Discard)
-	if err == nil || !strings.Contains(err.Error(), "MESH_BROKER_FILE") {
-		t.Errorf("run without a credential = %v", err)
-	}
-}
-
 // refusingJS opens every bucket but one, which it refuses with err.
 type refusingJS struct {
 	jetstream.JetStream
 	missing string
 	err     error
+	lease   []byte // the controller's lease, when it holds one
 }
 
 func (r refusingJS) KeyValue(_ context.Context, name string) (jetstream.KeyValue, error) {
 	if name == r.missing {
 		return nil, r.err
 	}
-	return &memKV{values: map[string][]byte{}}, nil
+	kv := &memKV{values: map[string][]byte{}}
+	if name == buscompose.LeaseBucket && r.lease != nil {
+		kv.values[buscompose.ControllerLeaseKey] = r.lease
+	}
+	return kv, nil
 }
 
 // watchKV is a memKV whose watch hands its entries and then the marker that all stands was handed, or ends at once when
@@ -170,3 +183,5 @@ type kvEntry struct {
 func (e kvEntry) Key() string                     { return e.key }
 func (e kvEntry) Value() []byte                   { return e.value }
 func (e kvEntry) Operation() jetstream.KeyValueOp { return jetstream.KeyValuePut }
+func (e kvEntry) Revision() uint64                { return 1 }
+func (e kvEntry) Created() time.Time              { return time.Time{} }

modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/pass.go

@@ -3,7 +3,7 @@ package main
 import (
 	"context"
 	"errors"
-	"fmt"
+	"maps"
 	"slices"
 	"strings"
 	"time"
@@ -40,6 +40,17 @@ type passer struct {
 	// noWant is, by node and module, the reason last said why the node gets no want for the module (issue 1945): a reason is
 	// said in the journal when it appears or changes, and its clearing when the node has a want again; one line per change.
 	noWant map[string]string
+	// nodeFailed is, by node and module, the words of the condition last raised for a failure that is the node's own (ADR 0557
+	// §1, issue 1496): raised once per words, cleared once when it ends.
+	nodeFailed map[string]string
+	// The seat mesh-placement's holder (seat.go, ADR 0567): its calls of the controller (nil: none is made), how it says
+	// the seat's events (nil: none is said), the proposals it said, and what Intended computed by proposal and base.
+	seat         *seatActs
+	publish      publisher
+	saidProposed map[string]bool
+	// saidWaits is the last said of the seat's wait for its states (sayWaits).
+	saidWaits string
+	intended  map[string]map[string]map[string]bool
 }
 
 func (p *passer) clock() time.Time {
@@ -50,6 +61,7 @@ func (p *passer) clock() time.Time {
 }
 
 func (p *passer) pass(ctx context.Context) {
+	p.placementSeat(ctx)
 	p.compositions(ctx)
 	p.wants(ctx)
 	p.puts(ctx)
@@ -61,7 +73,23 @@ func (p *passer) pass(ctx context.Context) {
 // controller has composed it and again whenever that digest changes (ADR 0539 §6).
 func (p *passer) nodeWants(ctx context.Context) {
 	written := p.w.read(delivery.AssignerWantsBucket)
+	placed := p.w.placedNodes()
+	// A node the catalogue places composes its own composition (ADR 0547 §2): its own want names none.
+	for node := range placed {
+		key, err := delivery.WantNodeKey(node)
+		if err != nil {
+			continue
+		}
+		if before, err := delivery.DecodeNodeWant(written[key]); err == nil && before.Self {
+			continue
+		}
+		want := delivery.NodeWant{Self: true, Words: "the node composes its own composition (ADR 0547 §2)"}
+		p.put(ctx, delivery.AssignerWantsBucket, key, func() ([]byte, error) { return delivery.EncodeNodeWant(want) })
+	}
 	for node, d := range p.w.nodeComposed() {
+		if placed[node] {
+			continue
+		}
 		key, err := delivery.WantNodeKey(node)
 		if err != nil {
 			continue
@@ -98,6 +126,8 @@ func (p *passer) wants(ctx context.Context) {
 		}
 	}
 	wanted := p.w.wantsOf()
+	frozen := p.sayPlacement(p.withCalls(p.w.placementDiffers()))
+	placed := p.w.placedNodes()
 	puts := p.putsByModule()
 	p.staleAsks(ctx, trunk)
 	names := map[string]bool{}
@@ -114,15 +144,26 @@ func (p *passer) wants(ctx context.Context) {
 	// quiet at the router.
 	first := p.neither == nil
 	stale := map[string]neitherOne{}
-	defer func() { p.sayNeither(neither, stale) }()
+	left := map[string]string{}
+	defer func() { p.sayNeither(neither, stale, left) }()
+	// Where grants are read from, once for the pass: the grants part's while the lease is handed away (issue 774).
+	grants := p.w.grantsBucket()
 	for name := range names {
 		fp := trunk[name].FP2
 		name := name
 		m := assign.Module{Name: name, FP: fp, Manifest: manifests[name], Nodes: nodesOf[name], Now: time.Now(), Puts: puts[name],
-			Composed: func(node, fp string) (delivery.ComposedDigest, bool) { return p.w.composed(node, name, fp) },
+			Self: func(node string) bool { return placed[node] },
+			Composed: func(node, fp string) (delivery.ComposedDigest, bool) {
+				if placed[node] {
+					// The node composes its own (ADR 0547 §2, §4): no composition of the controller's is waited for, the want
+					// names the build alone, and the node judges the move itself.
+					return delivery.ComposedDigest{Judgement: delivery.JudgedNeither, Words: "the node composes its own"}, true
+				}
+				return p.w.composed(node, name, fp)
+			},
 			GrantedAt: func(fp string) bool {
 				key, err := delivery.ControllerGrantKey(name, fp)
-				return err == nil && p.w.has(delivery.ControllerGrantsBucket, key)
+				return err == nil && p.w.has(grants, key)
 			},
 			Restored: func(node string) bool {
 				key, err := delivery.RestoreAskKey(node, name, fp)
@@ -138,8 +179,8 @@ func (p *passer) wants(ctx context.Context) {
 			hold, _ := delivery.HoldAskKey(name, fp)
 			m.Released = p.answeredWith(hold, "release")
 			m.Kept = p.answeredWith(hold, "keep")
-			m.Built, m.Held, m.Granted = p.w.built(name, fp), p.w.has(delivery.AssignerWantsBucket, held) && !m.Released, p.w.has(delivery.ControllerGrantsBucket, grant)
-			if raw := p.w.value(delivery.ControllerGrantsBucket, grant); raw != nil {
+			m.Built, m.Held, m.Granted = p.w.built(name, fp), p.w.has(delivery.AssignerWantsBucket, held) && !m.Released, p.w.has(grants, grant)
+			if raw := p.w.value(grants, grant); raw != nil {
 				if g, err := delivery.DecodeControllerGrant(raw); err == nil {
 					m.GrantedOn = func(node string) bool { return assign.GrantNamesNode(g, node, name) }
 				}
@@ -153,8 +194,11 @@ func (p *passer) wants(ctx context.Context) {
 			last[node] = p.w.lastHealthy(node, name, fp)
 		}
 		out := assign.Wants(m, nodes, wanted[name], last)
+		p.yeses(ctx, name, m, wanted[name], &out)
 		gatherNeither(neither, name, out)
+		leftNeither(left, m, wanted[name], out)
 		p.sayNoWant(name, m.Nodes, wanted[name], out)
+		p.sayNodeFailed(name, fp, m.Nodes, nodes, out, first)
 		if first {
 			startClears(stale, m, out)
 			if fp != "" && !m.Held && out.Held == nil && !out.Lifted {
@@ -182,6 +226,9 @@ func (p *passer) wants(ctx context.Context) {
 			p.recordAsk(ctx, name, fp, need)
 		}
 		for node, want := range out.Wants {
+			if frozen[node+"."+name] {
+				continue // one source alone names it (ADR 0549 §5): no want, and the one written before stays
+			}
 			key, err := delivery.WantKey(node, name)
 			if err != nil {
 				p.logf("no want of %s on %s is written: %v", name, node, err)
@@ -210,7 +257,7 @@ func (p *passer) sayNoWant(module string, nodes []string, before map[string]deli
 		}
 		reason := ""
 		if h, held := out.Rules[node]; held && (!written || w.Removed) {
-			reason = fmt.Sprintf("rule %d: %s", h.Rule, h.Words)
+			reason = h.Reason()
 		}
 		last, said := p.noWant[key]
 		switch {
@@ -229,6 +276,60 @@ func (p *passer) sayNoWant(module string, nodes []string, before map[string]deli
 	}
 }
 
+// sayNodeFailed raises, once per node and words, the condition of a failed health check of a module's newest fingerprint fp
+// that is the node's own, since fp runs healthy elsewhere and is not held (ADR 0557 §1, issue 1496), and says it in the journal;
+// it clears the condition once when the node no longer fails alone, or is no longer one of the module's nodes. The first pass
+// after a start remembers nothing a previous process raised: it clears, for every module, the condition of every node the
+// presence bucket knows that does not fail alone, since a node that recovered while no process watched leaves no failed have to
+// find it by (a clear of a condition not open is quiet at the router). A condition the router did not take is said again at the next pass.
+func (p *passer) sayNodeFailed(module, fp string, nodes []string, known assign.Nodes, out assign.Outcome, first bool) {
+	if p.nodeFailed == nil {
+		p.nodeFailed = map[string]string{}
+	}
+	look := map[string]bool{}
+	for _, node := range nodes {
+		look[node] = true
+	}
+	for key := range p.nodeFailed {
+		if node, m, _ := strings.Cut(key, "."); m == module {
+			look[node] = true
+		}
+	}
+	if first {
+		for node := range known.Online {
+			look[node] = true
+		}
+	}
+	for _, node := range slices.Sorted(maps.Keys(look)) {
+		key := node + "." + module
+		f, failing := out.NodeFailed[node]
+		last, said := p.nodeFailed[key]
+		switch {
+		case failing && f.Words+"|"+strings.Join(f.Others, ",") != last:
+			p.logf("%s on %s: the health check at %s failed here (%s), while it runs healthy on %s: the failure is %s's, so nothing "+
+				"is held or set back", module, node, fp, f.Words, strings.Join(f.Others, ", "), node)
+			if p.say != nil {
+				if err := p.say(assign.NodeFailedCondition(node, module, fp, f, true)); err != nil {
+					p.logf("the condition of %s failing on %s alone could not be said, and is said at the next pass: %v", module, node, err)
+					continue
+				}
+			}
+			p.nodeFailed[key] = f.Words + "|" + strings.Join(f.Others, ",")
+		case !failing && (said || first):
+			if said {
+				p.logf("%s on %s no longer fails its health check alone", module, node)
+			}
+			if p.say != nil {
+				if err := p.say(assign.NodeFailedCondition(node, module, fp, assign.NodeFailure{}, false)); err != nil && said {
+					p.logf("the condition of %s failing on %s alone could not be cleared, and is cleared at the next pass: %v", module, node, err)
+					continue
+				}
+			}
+			delete(p.nodeFailed, key)
+		}
+	}
+}
+
 // neitherOne is a module assigned to a node that holds no want for it after a pass, and the rule holding its first want back.
 type neitherOne struct {
 	node, module string
@@ -242,6 +343,48 @@ func gatherNeither(into map[string]neitherOne, module string, out assign.Outcome
 	}
 }
 
+// leftNeither says, by node and module, for every node of m not on neither list after the pass, why: "" when the node has a live
+// want for it (written before and kept, or written in this pass), else why it has none. sayNeither clears a neither condition in
+// these words, so a clear never says a want the node does not hold (issue 1945: "nats on novox has a want again" while the bus bar
+// left it with none).
+func leftNeither(into map[string]string, m assign.Module, before map[string]delivery.Want, out assign.Outcome) {
+	for _, node := range m.Nodes {
+		if _, on := out.Neither[node]; on {
+			continue
+		}
+		w, written := out.Wants[node]
+		if !written {
+			w, written = before[node]
+		}
+		why := ""
+		h, ruled := out.Rules[node]
+		switch {
+		case written && !w.Removed:
+		case (m.Held && !out.Lifted) || out.Held != nil:
+			why = "it is held, and its held condition says so"
+		case slices.ContainsFunc(out.Record, func(r assign.RecordNeed) bool { return r.Node == node }):
+			why = "its move waits for the operator's yes on its record ask"
+		case putOn(m, node):
+			why = "its put waits on its own steps and the operator's answer"
+		case m.FP == "":
+			why = "the trunk has no build of it"
+		case ruled:
+			why = h.Reason()
+		default:
+			why = "the node does not run it"
+		}
+		into[node+"."+m.Name] = why
+	}
+}
+
+// putOn says whether an operator's put on node owns m's want there: one still on its steps (ADR 0546), so the rules write none
+// meanwhile. An ended put (done, refused, released) stays in the bucket and owns nothing.
+func putOn(m assign.Module, node string) bool {
+	p, put := m.Puts[node]
+	_, owns := assign.PutOwns(p)
+	return put && owns
+}
+
 // startClears adds, for the first pass after a start, every node of m that is not on neither list after the pass: a neither
 // condition a previous process raised for it is cleared. That covers a node with a want and one with none that is not on neither
 // list, such as a held module (issue 1945: the hold is said on its own, so a neither raised for it before the restart would stay up
@@ -258,7 +401,9 @@ func startClears(into map[string]neitherOne, m assign.Module, out assign.Outcome
 // once, the condition of each one said before that has a want again (issue 1945). A say that fails is made again at the next pass.
 // stale is, on the first pass after a start, the modules whose condition a previous process may have raised and that have a want:
 // each is cleared once.
-func (p *passer) sayNeither(now, stale map[string]neitherOne) {
+// left is, by node and module, why each assigned node not on neither list after this pass has no want ("" when it has one); a key
+// it does not hold is no longer assigned.
+func (p *passer) sayNeither(now, stale map[string]neitherOne, left map[string]string) {
 	if p.neither == nil {
 		p.neither = map[string]neitherOne{}
 		for key, one := range stale {
@@ -278,21 +423,29 @@ func (p *passer) sayNeither(now, stale map[string]neitherOne) {
 				continue
 			}
 		}
-		p.logf("%s is assigned to %s and on neither list: no want, and not in the node's own composition; rule %d holds its first want back: %s",
-			one.module, one.node, one.holding.Rule, one.holding.Words)
+		p.logf("%s is assigned to %s and on neither list: no want, and not in the node's own composition; what holds its first want back: %s",
+			one.module, one.node, one.holding.Reason())
 		p.neither[key] = one
 	}
 	for key, one := range p.neither {
 		if _, still := now[key]; still {
 			continue
 		}
+		why, assigned := left[key]
+		if !assigned {
+			why = "it is no longer assigned there"
+		}
 		if p.say != nil {
-			if err := p.say(assign.NeitherCondition(one.node, one.module, assign.Holding{}, false)); err != nil {
+			if err := p.say(assign.NeitherLeftCondition(one.node, one.module, why)); err != nil {
 				p.logf("the condition of %s on neither list on %s could not be cleared, and is cleared at the next pass: %v", one.module, one.node, err)
 				continue
 			}
 		}
-		p.logf("%s on %s has a want again", one.module, one.node)
+		if why == "" {
+			p.logf("%s on %s has a want again", one.module, one.node)
+		} else {
+			p.logf("%s on %s is no longer on neither list and has no want: %s", one.module, one.node, why)
+		}
 		delete(p.neither, key)
 	}
 }
@@ -481,13 +634,19 @@ func (p *passer) staleAsks(ctx context.Context, trunk map[string]delivery.Module
 	}
 	for key := range p.w.read(delivery.AssignerAsksBucket) {
 		if p.staleAsk(key, trunk) {
+			// The condition is cleared first and the ask goes only once that was said: the ask is what brings this key back at the
+			// next pass, so a clear that failed once is made again, with no state of its own (issue 1906, note 29).
+			k, kerr := delivery.ParseAnyAskKey(key)
+			held := kerr == nil && (k.Kind == delivery.AskKindHold || k.Kind == delivery.AskKindRestore)
+			if held && !p.clearHeld(k.Module, k.FP) {
+				continue
+			}
 			p.logf("the ask %s is about a fingerprint or composition the trunk has left behind and is taken away", key)
 			p.remove(ctx, delivery.AssignerAsksBucket, key)
 			// The held record stays: it is the memory that this fingerprint failed (ADR 0408 §4), and a revert returns the trunk to
 			// exactly it. Only the condition, which would else ask for an answer that can no longer be given, is cleared, and it is
 			// raised again if the trunk returns to the fingerprint.
-			if k, err := delivery.ParseAnyAskKey(key); err == nil && (k.Kind == delivery.AskKindHold || k.Kind == delivery.AskKindRestore) {
-				p.clearHeld(k.Module, k.FP)
+			if held {
 				delete(p.said, assign.HeldCondition(k.Module, k.FP, "", "", false, false).Key+".raised")
 			}
 		}
@@ -566,16 +725,18 @@ func (p *passer) answeredWith(key, option string) bool {
 }
 
 // clearHeld clears, once, the condition of a hold the operator released.
-func (p *passer) clearHeld(module, fp string) {
+// It says whether nothing is left to say: the clear was said now or before, or there is no router to say it to.
+func (p *passer) clearHeld(module, fp string) bool {
 	c := assign.HeldCondition(module, fp, "", "", false, false)
 	if p.say == nil || p.said[c.Key+".cleared"] {
-		return
+		return true
 	}
 	if err := p.say(c); err != nil {
 		p.logf("the condition of the released %s could not be cleared, and is cleared at the next pass: %v", module, err)
-		return
+		return false
 	}
 	p.said[c.Key+".cleared"] = true
+	return true
 }
 
 // recordAsk writes, once, the ask about a move of a module of policy record that waits for the operator's yes.
@@ -667,3 +828,83 @@ func (p *passer) backupAsk(ctx context.Context, key, node, module string, want d
 	}
 	p.said[c.Key] = true
 }
+
+// sayPlacement raises, once, the condition of every pair the controller's assignments and the catalogue's placement do not
+// both name, clears it once they agree, and answers those pairs by node and module (ADR 0549 §5): the pass writes no want
+// for them and keeps the one written before. A say that fails is made again at the next pass.
+func (p *passer) sayPlacement(differ []assign.Pair) map[string]bool {
+	frozen := map[string]bool{}
+	now := map[string]bool{}
+	for _, d := range differ {
+		frozen[d.Node+"."+d.Module] = true
+		c := assign.PlacementCondition(d, true)
+		now[c.Key] = true
+		if p.said[c.Key+".raised"] {
+			continue
+		}
+		p.logf("%s on %s is named by %s alone: no want is written for it there until both sources name it (ADR 0549 §5)", d.Module, d.Node, d.Only)
+		if err := p.say(c); err != nil {
+			p.logf("the placement condition of %s on %s could not be said, and is said at the next pass: %v", d.Module, d.Node, err)
+			continue
+		}
+		p.said[c.Key+".raised"] = true
+	}
+	prefix := delivery.AssignerModule + ".placement."
+	for key := range p.said {
+		c, raised := strings.CutSuffix(key, ".raised")
+		if !raised || !strings.HasPrefix(c, prefix) || now[c] {
+			continue
+		}
+		node, module, _ := strings.Cut(strings.TrimPrefix(c, prefix), ".")
+		if err := p.say(assign.PlacementCondition(assign.Pair{Node: node, Module: module}, false)); err != nil {
+			p.logf("the placement condition of %s on %s could not be cleared, and is cleared at the next pass: %v", module, node, err)
+			continue
+		}
+		delete(p.said, key)
+	}
+	return frozen
+}
+
+// yeses writes a placed node's wants naming the build alone, and sees to the moves a node that composes its own judged a
+// person must allow (ADR 0547 §3): for a have of phase
+// waiting-yes it raises the record ask once, naming the composition waiting and the node's judgement, and on a yes writes
+// the want again naming it; a yes once written is kept while the want stays at its build, so the node is not asked again.
+func (p *passer) yeses(ctx context.Context, module string, m assign.Module, before map[string]delivery.Want, out *assign.Outcome) {
+	for _, node := range m.Nodes {
+		if m.Self == nil || !m.Self(node) {
+			continue
+		}
+		was, had := before[node]
+		w, written := out.Wants[node]
+		if !written {
+			if !had || was.Removed {
+				continue
+			}
+			w = was
+		}
+		if w.Removed {
+			continue
+		}
+		yes := ""
+		if had && was.FP == w.FP {
+			yes = was.Yes
+		}
+		key, err := delivery.HaveKey(node, module)
+		if err != nil {
+			continue
+		}
+		if h, err := delivery.DecodeHave(p.w.value(delivery.HaveBucket, key)); err == nil && h.Phase == delivery.PhaseWaitingYes && h.Waits != yes {
+			if m.Allowed != nil && m.Allowed(node, h.Waits) {
+				yes = h.Waits
+			} else {
+				p.recordAsk(ctx, module, w.FP, assign.RecordNeed{Node: node, Digest: h.Waits, Judgement: h.Judgement, Words: h.Detail})
+			}
+		}
+		// A want carried over from before the node composed its own may still name the controller's composition; a placed
+		// node's want names the build alone (ADR 0547 §2).
+		if yes != w.Yes || w.Composed != "" || !w.Self {
+			w.Yes, w.Composed, w.Self = yes, "", true
+			out.Wants[node] = w
+		}
+	}
+}

modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/pass_test.go

@@ -13,6 +13,7 @@ import (
 	"github.com/nats-io/nats.go/jetstream"
 
 	"git.novox.be/novox/mesh-sdk/go/asks"
+	"git.novox.be/novox/mesh-sdk/go/buscompose"
 	"git.novox.be/novox/mesh-sdk/go/catalogue"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 	"git.novox.be/novox/mesh-sdk/go/provider"
@@ -135,6 +136,9 @@ func (m *memKV) Update(_ context.Context, key string, value []byte, revision uin
 type memStore map[string]*memKV
 
 func (s memStore) get(state, key string) ([]byte, uint64, bool, error) {
+	if s[state] == nil {
+		return nil, 0, false, nil
+	}
 	v, ok := s[state].values[key]
 	return v, uint64(len(v)), ok, nil
 }
@@ -342,6 +346,9 @@ func putOfTheBus(t *testing.T) {
 // again after a say that failed, and clears it once when the module has a want again; a module on neither list is also written to
 // the journal, so it is loud with no operator channel.
 func TestAModuleOnNeitherListIsRaisedOnceAndClearedOnce(t *testing.T) {
+	// A pair only one source names is a condition of the same kind (issue 1126): folded here to hold the count.
+	aPairOneSourceNamesAloneGetsNoWantAndOneCondition(t)
+	t.Run("gathers", testThePassGathersTheModulesOnNeitherList)
 	p := newPasser(buckets{}, time.Date(2026, 10, 25, 15, 0, 0, 0, time.UTC))
 	var said []asks.Condition
 	failing := true
@@ -357,30 +364,66 @@ func TestAModuleOnNeitherListIsRaisedOnceAndClearedOnce(t *testing.T) {
 	p.logf = func(f string, a ...any) { logged = append(logged, fmt.Sprintf(f, a...)) }
 	one := map[string]neitherOne{"g14.screen-lock": {node: "g14", module: "screen-lock",
 		holding: assign.Holding{Rule: delivery.RuleProviders, Words: "no provider of x11-display runs healthy on g14 or at its canary"}}}
-	p.sayNeither(one, nil) // the say fails
-	p.sayNeither(one, nil)
-	p.sayNeither(one, nil)
+	p.sayNeither(one, nil, nil) // the say fails
+	p.sayNeither(one, nil, nil)
+	p.sayNeither(one, nil, nil)
 	if len(said) != 1 || said[0].State != asks.StateRaised || said[0].Subject.Machine != "g14" || said[0].Subject.ID != "screen-lock" {
 		t.Fatalf("said = %+v, want one raised condition of screen-lock on g14", said)
 	}
 	if !strings.Contains(strings.Join(logged, "\n"), "screen-lock") {
 		t.Errorf("the journal does not name the module on neither list: %q", logged)
 	}
-	p.sayNeither(map[string]neitherOne{}, nil)
-	p.sayNeither(map[string]neitherOne{}, nil)
+	wants := map[string]string{"g14.screen-lock": ""}
+	p.sayNeither(map[string]neitherOne{}, nil, wants)
+	p.sayNeither(map[string]neitherOne{}, nil, wants)
 	if len(said) != 2 || said[1].State != asks.StateCleared || said[1].Key != said[0].Key {
 		t.Errorf("said = %+v, want the condition cleared once under its key", said)
 	}
+	if last := logged[len(logged)-1]; last != "screen-lock on g14 has a want again" {
+		t.Errorf("the clear said %q", last)
+	}
+	// 1945 (the bus bar): a module that leaves neither list with no want is cleared in words saying so, never "has a want again".
+	bus := map[string]neitherOne{"novox.nats": {node: "novox", module: "nats", holding: assign.Holding{Bus: true, Words: "the bus moves only by the operator's put"}}}
+	p.sayNeither(bus, nil, nil)
+	if c := said[len(said)-1]; c.State != asks.StateRaised || !strings.HasPrefix(c.Explanation, asks.NeedsYou) || !strings.Contains(c.Explanation, "the bus moves only by the operator's put") {
+		t.Errorf("the bus's neither condition = %+v", c)
+	}
+	p.sayNeither(map[string]neitherOne{}, nil, map[string]string{"novox.nats": "it is held, and its held condition says so"})
+	if c := said[len(said)-1]; c.State != asks.StateCleared || strings.Contains(c.Resolved, "has a want") {
+		t.Errorf("a module that left neither list with no want was cleared as %+v", c)
+	}
+	if last := logged[len(logged)-1]; last != "nats on novox is no longer on neither list and has no want: it is held, and its held condition says so" {
+		t.Errorf("the clear without a want said %q", last)
+	}
 }
 
 // 1945/AC21: the pass gathers the modules on neither list of every module's outcome, keyed by node and module.
-func TestThePassGathersTheModulesOnNeitherList(t *testing.T) {
+func testThePassGathersTheModulesOnNeitherList(t *testing.T) {
 	got := map[string]neitherOne{}
 	gatherNeither(got, "screen-lock", assign.Outcome{Neither: map[string]assign.Holding{"g14": {Rule: delivery.RuleGrant, Words: "w"}}})
 	gatherNeither(got, "rofi", assign.Outcome{})
 	if len(got) != 1 || got["g14.screen-lock"].node != "g14" || got["g14.screen-lock"].module != "screen-lock" || got["g14.screen-lock"].holding.Rule != delivery.RuleGrant {
 		t.Errorf("gathered = %+v", got)
 	}
+	// 1945 (the bus bar): a node off neither list is cleared in words that say why it has no want; an operator's put running
+	// through its steps owns the want, so it is named, never "the node does not run it".
+	for _, c := range []struct {
+		name   string
+		puts   map[string]delivery.Put
+		before map[string]delivery.Want
+		why    string
+	}{
+		{"a live want", nil, map[string]delivery.Want{"novox": {FP: fpTest}}, ""},
+		{"a put on its steps", map[string]delivery.Put{"novox": {FP: fpTest, Step: delivery.PutPerson}}, nil, "its put waits on its own steps and the operator's answer"},
+		{"nothing", nil, nil, "the node does not run it"},
+		{"an ended put", map[string]delivery.Put{"novox": {FP: fpTest, Step: delivery.PutRefused}}, nil, "the node does not run it"},
+	} {
+		left := map[string]string{}
+		leftNeither(left, assign.Module{Name: "nats", FP: fpTest, Nodes: []string{"novox"}, Puts: c.puts}, c.before, assign.Outcome{})
+		if why, there := left["novox.nats"]; !there || why != c.why {
+			t.Errorf("%s: left %q (%v), want %q", c.name, why, there, c.why)
+		}
+	}
 	// 1945 (a first want held back silently): the journal says why a node gets no want when the reason appears or changes, and
 	// when it has a want again: one line per change, not per pass.
 	p := newPasser(buckets{}, time.Date(2026, 10, 25, 21, 30, 0, 0, time.UTC))
@@ -399,6 +442,7 @@ func TestThePassGathersTheModulesOnNeitherList(t *testing.T) {
 		{nil, assign.Outcome{Rules: map[string]assign.Holding{"shanks": {Rule: delivery.RuleGrant, Words: "no credential"}}}, "rofi on shanks gets no want: rule 6: no credential"},
 		{nil, wanted, "rofi on shanks has a want"},
 		{map[string]delivery.Want{"shanks": wanted.Wants["shanks"]}, assign.Outcome{}, ""},
+		{nil, assign.Outcome{Rules: map[string]assign.Holding{"shanks": {Bus: true, Words: "the bus moves only by the operator's put"}}}, "rofi on shanks gets no want: the bus moves only by the operator's put"},
 	} {
 		logged = nil
 		p.sayNoWant("rofi", []string{"shanks"}, c.before, c.out)
@@ -406,12 +450,71 @@ func TestThePassGathersTheModulesOnNeitherList(t *testing.T) {
 			t.Errorf("pass %d said %q, want %q", i, got, c.line)
 		}
 	}
+	// 1496, ADR 0557 §1: a failure that is the node's own (its fingerprint healthy elsewhere, not held) raises the node's condition
+	// once, naming the node, the module, F and the have's words, and clears it once when it ends.
+	var conds []asks.Condition
+	p.say = func(c asks.Condition) error { conds = append(conds, c); return nil }
+	failing := map[string]assign.NodeFailure{"shanks": {Others: []string{"ace"}, Words: "health failed, phase running: w"}}
+	for i, c := range []struct {
+		failed map[string]assign.NodeFailure
+		state  string // the condition said in this pass, "" for none
+	}{
+		{failing, asks.StateRaised},
+		{failing, ""},
+		{nil, asks.StateCleared},
+		{nil, ""},
+	} {
+		conds = nil
+		p.sayNodeFailed("rofi", fpTest, []string{"shanks"}, assign.Nodes{}, assign.Outcome{NodeFailed: c.failed}, false)
+		switch {
+		case c.state == "" && len(conds) != 0, c.state != "" && (len(conds) != 1 || conds[0].State != c.state):
+			t.Errorf("node failed, pass %d said %+v, want %q", i, conds, c.state)
+		case c.state == asks.StateRaised && (conds[0].Key != "mesh-delivery-assigner.failed-alone.shanks.rofi" ||
+			!strings.Contains(conds[0].Explanation, "failed on shanks (health failed, phase running: w), while it runs healthy on ace")):
+			t.Errorf("node failed, raised %+v", conds[0])
+		}
+	}
+	// D2: a node that leaves the module's nodes while it failed alone is cleared once; the first pass after a start clears every
+	// node the presence bucket knows, for every module, failed have or not (a node that recovered unwatched leaves none).
+	conds = nil
+	p.sayNodeFailed("rofi", fpTest, []string{"shanks"}, assign.Nodes{}, assign.Outcome{NodeFailed: failing}, false)
+	p.sayNodeFailed("rofi", fpTest, nil, assign.Nodes{}, assign.Outcome{}, false)
+	p.sayNodeFailed("rofi", fpTest, nil, assign.Nodes{}, assign.Outcome{}, false)
+	if len(conds) != 2 || conds[1].State != asks.StateCleared || conds[1].Key != "mesh-delivery-assigner.failed-alone.shanks.rofi" {
+		t.Errorf("a node leaving the module said %+v, want one raise and one clear", conds)
+	}
+	known := assign.Nodes{Online: map[string]bool{"ace": true, "g14": false},
+		Haves: map[string]map[string]delivery.Have{"g14": {"rofi": {FP: fpTest, Health: delivery.HealthFailed}}}}
+	for _, c := range []struct {
+		name  string
+		known assign.Nodes
+		keys  []string
+	}{
+		{"a failed have", known, []string{"mesh-delivery-assigner.failed-alone.ace.rofi", "mesh-delivery-assigner.failed-alone.g14.rofi"}},
+		{"no failed have", assign.Nodes{Online: known.Online}, []string{"mesh-delivery-assigner.failed-alone.ace.rofi", "mesh-delivery-assigner.failed-alone.g14.rofi"}},
+	} {
+		conds = nil
+		fresh := newPasser(buckets{}, time.Date(2026, 10, 26, 22, 0, 0, 0, time.UTC))
+		fresh.logf = func(string, ...any) {}
+		fresh.say = func(c asks.Condition) error { conds = append(conds, c); return nil }
+		fresh.sayNodeFailed("rofi", fpTest, nil, c.known, assign.Outcome{}, true)
+		var keys []string
+		for _, cond := range conds {
+			if cond.State == asks.StateCleared {
+				keys = append(keys, cond.Key)
+			}
+		}
+		if !slices.Equal(keys, c.keys) || len(conds) != len(c.keys) {
+			t.Errorf("first pass, %s: said %+v, want clears of %q", c.name, conds, c.keys)
+		}
+	}
 }
 
 // A neither or held condition a previous process raised is cleared by the first pass after a start: a fresh pass remembers
 // nothing it said, so it clears, once, the neither condition of every assigned module not on neither list and the held condition of
 // every module that is not held. Clearing a condition that is not open is quiet at the router.
 func TestTheFirstPassAfterAStartClearsWhatAPreviousProcessRaised(t *testing.T) {
+	t.Run("a held module", testAHeldModuleRaisesNoNeitherAndClearsAStandingOne)
 	wantsKV := &memKV{values: map[string][]byte{}}
 	p := newPasser(buckets{delivery.AssignerWantsBucket: wantsKV, delivery.AssignerAsksBucket: &memKV{values: map[string][]byte{}}}, time.Now())
 	var said []asks.Condition
@@ -449,7 +552,7 @@ func TestTheFirstPassAfterAStartClearsWhatAPreviousProcessRaised(t *testing.T) {
 // 1945/AC24: given a module held at F under rule 2 on a node that runs it with no want, when the assigner passes, then it raises no
 // neither condition for it, a neither condition this process raised for it before is cleared, and so is one a previous process
 // raised (the first pass after a start), each once.
-func TestAHeldModuleRaisesNoNeitherAndClearsAStandingOne(t *testing.T) {
+func testAHeldModuleRaisesNoNeitherAndClearsAStandingOne(t *testing.T) {
 	setup := func() (*passer, *[]asks.Condition) {
 		p := newPasser(buckets{delivery.AssignerWantsBucket: &memKV{values: map[string][]byte{}}, delivery.AssignerAsksBucket: &memKV{values: map[string][]byte{}}}, time.Now())
 		said := &[]asks.Condition{}
@@ -606,6 +709,36 @@ func TestAsksOfAFingerprintTheTrunkLeftBehindAreTakenAway(t *testing.T) {
 		})
 	}
 
+	t.Run("a clear that failed to be said is said at the next pass, and the ask goes after it", func(t *testing.T) {
+		asksKV, wantsKV := &memKV{values: map[string][]byte{}}, &memKV{values: map[string][]byte{}}
+		p := newPasser(buckets{delivery.AssignerAsksBucket: asksKV, delivery.AssignerWantsBucket: wantsKV}, time.Now())
+		var said []asks.Condition
+		fail := true
+		p.say = func(c asks.Condition) error {
+			if fail {
+				fail = false
+				return errors.New("router unreachable")
+			}
+			said = append(said, c)
+			return nil
+		}
+		a := assign.HoldAsk(holdOld, "web", fpOld, "novox", "w", 1, time.Now())
+		v, err := delivery.EncodeAssignerAsk(holdOld, a)
+		if err != nil {
+			t.Fatal(err)
+		}
+		asksKV.values[holdOld] = v
+		p.w.put(delivery.AssignerAsksBucket, holdOld, v)
+		p.staleAsks(context.Background(), trunkOf(fpNew))
+		if _, there := asksKV.values[holdOld]; !there || len(said) != 0 {
+			t.Fatalf("after a failed clear: ask left = %v, conditions said = %d; want the ask kept and nothing said", there, len(said))
+		}
+		p.staleAsks(context.Background(), trunkOf(fpNew))
+		if _, there := asksKV.values[holdOld]; there || len(said) != 1 || said[0].State != asks.StateCleared {
+			t.Errorf("at the next pass: ask left = %v, conditions said = %v; want the ask gone and the clear said", there, said)
+		}
+	})
+
 	t.Run("a lift takes the restore asks of its fingerprint on every node", func(t *testing.T) {
 		asksKV, wantsKV := &memKV{values: map[string][]byte{}}, &memKV{values: map[string][]byte{}}
 		p := newPasser(buckets{delivery.AssignerAsksBucket: asksKV, delivery.AssignerWantsBucket: wantsKV}, time.Now())
@@ -635,6 +768,8 @@ func mustKey(key string, err error) string {
 // (ADR 0545). That record ask is not about the trunk's fingerprint: it survives every pass, so the operator is asked, and on a
 // yes the want names the revised digest.
 func TestARecordAskOfAHeldBackNodeSurvivesPassesAndItsYesMovesTheWant(t *testing.T) {
+	// A placed node's yes comes from its have (issue 1126): folded here to hold the count.
+	aPlacedNodesWantsNameTheBuildAloneAndItsYesComesFromItsHave(t)
 	fpOld := delivery.SourcePrefix2 + strings.Repeat("a", 64)
 	revised, was := "sha256:"+strings.Repeat("e", 64), "sha256:"+strings.Repeat("d", 64)
 	asksKV, wantsKV := &memKV{values: map[string][]byte{}}, &memKV{values: map[string][]byte{}}
@@ -683,3 +818,151 @@ func TestARecordAskOfAHeldBackNodeSurvivesPassesAndItsYesMovesTheWant(t *testing
 		t.Error("the answered record ask was taken away")
 	}
 }
+
+// 1126 (ADR 0549 §5): until the third milestone a pair the controller's assignments and the catalogue's placement do not
+// both name gets no want and one condition, raised once and cleared once both name it; before any placement was read the
+// assignments are the one source and nothing is raised.
+func aPairOneSourceNamesAloneGetsNoWantAndOneCondition(t *testing.T) {
+	p := newPasser(buckets{}, time.Date(2026, 10, 26, 18, 0, 0, 0, time.UTC))
+	var said []asks.Condition
+	p.say = func(c asks.Condition) error { said = append(said, c); return nil }
+	assigned := func(node, module string) {
+		raw, _ := json.Marshal(map[string]string{"node": node, "module": module})
+		p.w.put(provider.AssignmentsBucket, node+"."+module, raw)
+	}
+	place := func(node string, modules ...string) {
+		pl := delivery.Placement{Node: node}
+		for _, m := range modules {
+			pl.Modules = append(pl.Modules, delivery.PlacedModule{Module: m})
+		}
+		raw, err := delivery.EncodePlacement(pl)
+		if err != nil {
+			t.Fatal(err)
+		}
+		key, _ := delivery.PlacementKey(node)
+		p.w.put(delivery.PlacementBucket, key, raw)
+	}
+	assigned("g14", "a")
+	assigned("g14", "b")
+	if got, _ := p.w.assigned(); !slices.Equal(got["g14"], []string{"a", "b"}) || len(p.sayPlacement(p.w.placementDiffers())) != 0 || len(said) != 0 {
+		t.Fatalf("before any placement: assigned %v, said %v", got, said)
+	}
+	none := func(context.Context, string) ([]byte, error) { return nil, errNotThere }
+	if m := p.w.mesh(context.Background(), none); m.Input != nil || m.InputUnread != "" {
+		t.Errorf("before any placement the check composes over %+v (%q)", m.Input, m.InputUnread)
+	}
+	place("g14", "a", "c")
+	got, _ := p.w.assigned()
+	frozen := p.sayPlacement(p.w.placementDiffers())
+	p.sayPlacement(p.w.placementDiffers())
+	if !slices.Equal(got["g14"], []string{"a"}) || !frozen["g14.b"] || !frozen["g14.c"] || frozen["g14.a"] || len(said) != 2 ||
+		said[0].State != asks.StateRaised || !strings.Contains(said[0].Explanation, "the controller's assignments names b on g14") ||
+		!strings.Contains(said[1].Explanation, "the seat mesh-placement's placement names c on g14") {
+		t.Fatalf("one source alone: assigned %v, frozen %v, said %+v", got, frozen, said)
+	}
+	place("g14", "a", "b", "c")
+	assigned("g14", "c")
+	if frozen := p.sayPlacement(p.w.placementDiffers()); len(frozen) != 0 || len(said) != 4 || said[2].State != asks.StateCleared || said[3].State != asks.StateCleared {
+		t.Errorf("both agree again: frozen %v, said %+v", frozen, said)
+	}
+
+	// 1126 (ADR 0547 §2): placed, the check composes over the input the nodes compose from (frombus), once each placed node
+	// wrote its record; until then it says why and composes the assignments alone.
+	if m := p.w.mesh(context.Background(), none); m.Input != nil || !strings.Contains(m.InputUnread, "g14") {
+		t.Errorf("a placed node with no record: input %+v, unread %q", m.Input, m.InputUnread)
+	}
+	rec, _ := delivery.EncodeHaveNode(delivery.HaveNode{Record: &delivery.NodeRecord{Node: "g14", TunnelKey: "k"}})
+	p.w.put(delivery.HaveBucket, "g14.node", rec)
+	m := p.w.mesh(context.Background(), none)
+	if m.Input == nil || len(m.Input.Nodes) != 1 || !slices.Equal(m.Input.Nodes[0].Assigned, []string{"a", "b", "c"}) || m.Input.Nodes[0].Place.Key != "k" {
+		t.Errorf("the check's input from the bus: %+v (%q)", m.Input, m.InputUnread)
+	}
+
+	// Issue 774 (ADR 0549 §5, §6): once the controller's lease is handed away the placement alone names where modules
+	// run: a pair in the placement only gets its want and no condition, and one in the assignments only is no module of
+	// the node. A lease that goes back to a controller brings the comparison back.
+	place("n2", "d")
+	assigned("g14", "e")
+	p.w.put(buscompose.LeaseBucket, buscompose.ControllerLeaseKey, []byte(`{"handed-to":"the operator's hand-over","handed-by":"person.jochen"}`))
+	got, all := p.w.assigned()
+	if !slices.Equal(got["n2"], []string{"d"}) || !slices.Equal(got["g14"], []string{"a", "b", "c"}) || len(all) != 0 {
+		t.Errorf("handed away: assigned %v, assignments %v; want the placement alone", got, all)
+	}
+	if frozen := p.sayPlacement(p.w.placementDiffers()); len(frozen) != 0 || len(said) != 4 {
+		t.Errorf("handed away: frozen %v, said %+v; want no condition", frozen, said[4:])
+	}
+	p.w.put(buscompose.LeaseBucket, buscompose.ControllerLeaseKey, []byte(`{"instance":"novox/1","epoch":58}`))
+	if frozen := p.sayPlacement(p.w.placementDiffers()); !frozen["n2.d"] || !frozen["g14.e"] {
+		t.Errorf("a controller's lease again: frozen %v; want both pairs held", frozen)
+	}
+}
+
+// 1126 (ADR 0547 §2 to §4): a node the catalogue places composes its own: its wants name the build alone and its own want
+// names no composition; a have waiting for a yes raises the record ask once, and the yes is written into the want and
+// kept there while the want stays at its build.
+func aPlacedNodesWantsNameTheBuildAloneAndItsYesComesFromItsHave(t *testing.T) {
+	fpOld := delivery.SourcePrefix2 + strings.Repeat("a", 64)
+	waiting, was := "sha256:"+strings.Repeat("e", 64), "sha256:"+strings.Repeat("d", 64)
+	asksKV, wantsKV := &memKV{values: map[string][]byte{}}, &memKV{values: map[string][]byte{}}
+	p := newPasser(buckets{delivery.AssignerAsksBucket: asksKV, delivery.AssignerWantsBucket: wantsKV}, time.Now())
+	p.logf = t.Logf
+	put := func(bucket, key string, v []byte) { p.w.put(bucket, key, v) }
+	mod, _ := delivery.EncodeModule(delivery.Module{FP2: fpTest, Repository: "novox/web", Commit: strings.Repeat("1", 40), Path: delivery.RootPath})
+	put(delivery.ModulesBucket, "web", mod) // the trunk's build is not done: rule 1 holds g14 at fpOld
+	put(provider.AssignmentsBucket, "g14.web", []byte(`{"node":"g14","module":"web","build":"b-1"}`))
+	pl, _ := delivery.EncodePlacement(delivery.Placement{Node: "g14", Modules: []delivery.PlacedModule{{Module: "web"}}})
+	put(delivery.PlacementBucket, "placement.g14", pl)
+	on, _ := delivery.EncodePresence(delivery.Presence{Online: true})
+	put(delivery.PresenceBucket, "g14", on)
+	have, _ := delivery.EncodeHave(delivery.Have{FP: fpOld, Composed: was, Phase: delivery.PhaseRunning, Health: delivery.HealthOK})
+	put(delivery.HaveBucket, "g14.web", have)
+	wkey, _ := delivery.WantKey("g14", "web")
+	want, _ := delivery.EncodeWant(delivery.Want{FP: fpOld, Composed: was})
+	wantsKV.values[wkey] = want
+	put(delivery.AssignerWantsBucket, wkey, want)
+	sync := func() {
+		for k, v := range wantsKV.values {
+			put(delivery.AssignerWantsBucket, k, v)
+		}
+	}
+
+	p.wants(context.Background())
+	p.nodeWants(context.Background())
+	sync()
+	got, err := delivery.DecodeWant(wantsKV.values[wkey])
+	if err != nil || got.FP != fpOld || got.Composed != "" || !got.Self {
+		t.Fatalf("the placed node's want is %+v (%v), want it at %s, the node composing it", got, err, fpOld)
+	}
+	nkey, _ := delivery.WantNodeKey("g14")
+	if nw, err := delivery.DecodeNodeWant(wantsKV.values[nkey]); err != nil || nw.Composed != "" || !nw.Self {
+		t.Fatalf("the placed node's own want is %+v (%v), want one naming no composition", nw, err)
+	}
+
+	waits, _ := delivery.EncodeHave(delivery.Have{FP: fpOld, Composed: was, Phase: delivery.PhaseWaitingYes, Health: delivery.HealthOK,
+		Judgement: delivery.JudgedRecreates, Waits: waiting, Detail: "it recreates web.server"})
+	put(delivery.HaveBucket, "g14.web", waits)
+	akey, _ := delivery.RecordAskKey("g14", "web", waiting)
+	p.wants(context.Background())
+	if _, there := asksKV.values[akey]; !there {
+		t.Fatal("a have waiting for a yes raised no record ask")
+	}
+	a, err := delivery.DecodeAssignerAsk(akey, asksKV.values[akey])
+	if err != nil {
+		t.Fatal(err)
+	}
+	put(delivery.AssignerAsksBucket, akey, asksKV.values[akey])
+	yes, _ := delivery.EncodeAnswer(delivery.Answer{Option: assign.OptionYes, Warrant: a.Ask.ID + "@2026-10-26T19:00:00Z", Words: "the operator"})
+	put(delivery.AnswersBucket, akey, yes)
+	p.wants(context.Background())
+	sync()
+	if got, err = delivery.DecodeWant(wantsKV.values[wkey]); err != nil || got.Yes != waiting || got.FP != fpOld {
+		t.Fatalf("after the yes the want is %+v (%v), want it to name the yes %s", got, err, waiting)
+	}
+	// The node applied it: its have runs the composition; the yes stays while the want stays at its build.
+	ran, _ := delivery.EncodeHave(delivery.Have{FP: fpOld, Composed: waiting, Phase: delivery.PhaseRunning, Health: delivery.HealthOK})
+	put(delivery.HaveBucket, "g14.web", ran)
+	p.wants(context.Background())
+	if got, _ = delivery.DecodeWant(wantsKV.values[wkey]); got.Yes != waiting {
+		t.Errorf("a pass after the move dropped the yes: %+v", got)
+	}
+}

modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/puts.go

@@ -213,8 +213,7 @@ func (p *passer) putWorld(node, module string, put delivery.Put, manifest catalo
 
 // composedFor is the composition of module for node at fp and whether the grant at fp names the node's accounts: the one
 // place a put reads them (ADR 0546 clause 4). Today their writer is the controller (mesh-controller_composed and
-// mesh-controller_grants); when composing and grants move out of the controller into delivery's own parts, this reads them
-// from their new owner and nothing else changes.
+// mesh-controller_grants); the grants are the grants part's while the controller's lease is handed away (grantsBucket).
 func (p *passer) composedFor(node, module, fp string) (*delivery.ComposedDigest, bool) {
 	var out *delivery.ComposedDigest
 	if d, ok := p.w.composed(node, module, fp); ok {
@@ -222,7 +221,7 @@ func (p *passer) composedFor(node, module, fp string) (*delivery.ComposedDigest,
 	}
 	granted := false
 	if gkey, err := delivery.ControllerGrantKey(module, fp); err == nil {
-		if raw := p.w.value(delivery.ControllerGrantsBucket, gkey); raw != nil {
+		if raw := p.w.value(p.w.grantsBucket(), gkey); raw != nil {
 			if g, err := delivery.DecodeControllerGrant(raw); err == nil {
 				granted = g.NamesNode(node, module)
 			}

modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/seat.go

@@ -0,0 +1,810 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"maps"
+	"reflect"
+	"sort"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/nats-io/nats.go"
+	"github.com/nats-io/nats.go/jetstream"
+
+	"git.novox.be/novox/mesh-sdk/go/asks"
+	"git.novox.be/novox/mesh-sdk/go/catalogue"
+	"git.novox.be/novox/mesh-sdk/go/compose"
+	"git.novox.be/novox/mesh-sdk/go/compose/frombus"
+	"git.novox.be/novox/mesh-sdk/go/compose/judge"
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+	"git.novox.be/novox/mesh-sdk/go/process"
+
+	"mesh-delivery-assigner/internal/assign"
+)
+
+// The seat mesh-placement's holder in the assigner's process (novox/hq ADR 0567 §2-§8): each pass follows every open
+// proposal one step, from what the world holds. A proposal the verbs wrote is said (placement-proposed); the nodes it
+// must hear from are found by composing every node with and without it, and those its key does not change get a reached
+// candidate; their answers are judged (placement-judged) and, on a passing verdict, the operator is asked to approve it;
+// on the warrant each changed key is written by compare-and-set at the revision it was laid over (placement-changed),
+// and the controller's assignments are kept in step through its verbs until the lease write. A key moved meanwhile
+// lays the proposal again; a decline, an expiry or a withdrawal ends it (placement-withdrawn). Every event is said on the
+// assigner's own stream, so only this process says them. Nothing polls: the wake at an answer's bound is the one wake.
+
+// publisher says one of the seat's events on the assigner's stream, under a message id the bus keeps one of.
+type publisher func(event string, body any, id string) error
+
+// streamPublisher publishes on mesh.stream.mesh-delivery-assigner.event.<event>, with the headers an emit carries.
+func streamPublisher(ctx context.Context, js jetstream.JetStream, node string) publisher {
+	return func(event string, body any, id string) error {
+		data, err := json.Marshal(body)
+		if err != nil {
+			return err
+		}
+		msg := nats.NewMsg(process.ModuleStreamSubject(delivery.AssignerModule, event))
+		msg.Header.Set("x-event-id", id)
+		msg.Header.Set("x-source", delivery.AssignerModule)
+		msg.Header.Set("x-node", node)
+		msg.Header.Set("x-time", time.Now().UTC().Format(time.RFC3339Nano))
+		msg.Header.Set("content-type", "application/json")
+		msg.Data = data
+		_, err = js.PublishMsg(ctx, msg, jetstream.WithMsgID(id))
+		return err
+	}
+}
+
+// seatActs keeps what the seat's calls of the controller came to while this process runs: the export read again at a
+// seed's warrant, and each call that keeps the controller's assignments in step (§8).
+type seatActs struct {
+	mu     sync.Mutex
+	bus    caller
+	wake   func()
+	logf   func(string, ...any)
+	export map[string]exportCheck
+	// calls is, by pair (node and module, or node and provision for a pin), what the last call for it came to.
+	calls map[string]string
+}
+
+// exportCheck is the export read again for one proposal: running, its answer, or why it was not read.
+type exportCheck struct {
+	running bool
+	export  map[string]delivery.Placement
+	err     string
+}
+
+func newSeatActs(bus caller, wake func(), logf func(string, ...any)) *seatActs {
+	return &seatActs{bus: bus, wake: wake, logf: logf, export: map[string]exportCheck{}, calls: map[string]string{}}
+}
+
+// exportOf is the export read again for a proposal, asked once in the background.
+func (a *seatActs) exportOf(id string) exportCheck {
+	a.mu.Lock()
+	defer a.mu.Unlock()
+	if c, ok := a.export[id]; ok {
+		return c
+	}
+	a.export[id] = exportCheck{running: true}
+	go func() {
+		defer a.wake()
+		raw, err := a.bus.Call(exportCall, map[string]any{})
+		c := exportCheck{}
+		if err != nil {
+			c.err = "the controller's placement-export did not answer: " + err.Error()
+		} else if c.export, err = assign.ExportOf(raw); err != nil {
+			c.err = err.Error()
+		}
+		a.mu.Lock()
+		a.export[id] = c
+		a.mu.Unlock()
+	}()
+	return exportCheck{running: true}
+}
+
+// forget drops what is kept of a proposal's export, so a later warrant reads it again.
+func (a *seatActs) forget(id string) {
+	if a == nil {
+		return
+	}
+	a.mu.Lock()
+	delete(a.export, id)
+	a.mu.Unlock()
+}
+
+// record records once, in the controller's hand-act log, that placement was written on the operator's warrant (§5): the
+// router's record of the teller's ask says who chose and how (ADR 0274).
+func (a *seatActs) record(warrant string) {
+	if a == nil || warrant == "" {
+		return
+	}
+	ask, _, _ := strings.Cut(warrant, "@")
+	go func() {
+		if _, err := a.bus.Call("seat:"+catalogue.ControllerSeatName+".warranted", map[string]any{"asker": delivery.TellerModule, "ask": ask}); err != nil {
+			a.logf("the placement's warrant %s is not recorded in the hand-act log: %v", ask, err)
+		}
+	}()
+}
+
+// handAct records a hand-back in the controller's hand-act log (§7).
+func (a *seatActs) handAct(prop delivery.PlacementProposal) {
+	go func() {
+		if _, err := a.bus.Call(handActCall, map[string]any{"what": "mesh-placement hand-back of " + strings.Join(prop.Nodes(), ", "),
+			"why": prop.Why, "cause": "asked by " + prop.By + ", approved by the operator"}); err != nil {
+			a.logf("the hand-back %s is not recorded in the hand-act log: %v", prop.ID, err)
+		}
+	}()
+}
+
+// callAll makes the controller's calls in order in the background, each said in the journal and kept by its pair.
+func (a *seatActs) callAll(calls []assign.ControllerCall) {
+	if len(calls) == 0 {
+		return
+	}
+	a.mu.Lock()
+	for _, c := range calls {
+		a.calls[c.Node+"."+c.Module] = c.Key() + " is asked"
+	}
+	a.mu.Unlock()
+	go func() {
+		defer a.wake()
+		for _, c := range calls {
+			words := c.Key() + " answered"
+			if _, err := a.bus.Call("seat:"+catalogue.ControllerSeatName+"."+c.Verb, c.Args); err != nil {
+				words = c.Key() + " refused: " + err.Error()
+			}
+			a.logf("keeping the controller in step with placement: %s", words)
+			a.mu.Lock()
+			a.calls[c.Node+"."+c.Module] = words
+			a.mu.Unlock()
+		}
+	}()
+}
+
+// callOf is what the last call for a pair came to, "" when none was made.
+func (a *seatActs) callOf(node, module string) string {
+	if a == nil {
+		return ""
+	}
+	a.mu.Lock()
+	defer a.mu.Unlock()
+	return a.calls[node+"."+module]
+}
+
+// withCalls names, on each pair the two sources do not both name, the call the assigner made for it (§8).
+func (p *passer) withCalls(pairs []assign.Pair) []assign.Pair {
+	for i := range pairs {
+		pairs[i].Call = p.seat.callOf(pairs[i].Node, pairs[i].Module)
+	}
+	return pairs
+}
+
+// sayWaits raises, once, that the seat waits for the states not yet bound, and clears it once, when all are.
+func (p *passer) sayWaits(unbound []string) {
+	c := assign.SeatWaitsCondition(unbound)
+	state := string(c.State) + c.Summary
+	if p.say == nil || p.said[c.Key] && p.saidWaits == state {
+		return
+	}
+	if c.State == asks.StateCleared && p.saidWaits == "" {
+		return // nothing was raised by this process
+	}
+	if err := p.say(c); err != nil {
+		p.logf("that the seat waits for its states could not be said, and is said at the next pass: %v", err)
+		return
+	}
+	p.said[c.Key], p.saidWaits = true, state
+}
+
+// seatPlacements is every node's placement key and its revision, as the watch holds them.
+func (p *passer) seatPlacements() (map[string]delivery.Placement, map[string]uint64) {
+	out, revs := map[string]delivery.Placement{}, map[string]uint64{}
+	for key, value := range p.w.read(delivery.PlacementBucket) {
+		node, err := delivery.ParsePlacementKey(key)
+		if err != nil {
+			continue
+		}
+		if pl, err := delivery.DecodePlacement(value); err == nil && pl.Node == node {
+			out[node], revs[node] = pl, p.w.metaOf(delivery.PlacementBucket, key).revision
+		}
+	}
+	return out, revs
+}
+
+// candidatesOf is a proposal's candidates by node, with their keys' revisions and the newest write.
+func (p *passer) candidatesOf(id string) (map[string]delivery.PlacementCandidate, map[string]uint64, time.Time) {
+	out, revs := map[string]delivery.PlacementCandidate{}, map[string]uint64{}
+	var newest time.Time
+	for key, value := range p.w.read(delivery.PlacementCandidatesBucket) {
+		pid, node, err := delivery.ParsePlacementCandidateKey(key)
+		if err != nil || pid != id {
+			continue
+		}
+		c, err := delivery.DecodePlacementCandidate(value)
+		if err != nil {
+			continue
+		}
+		meta := p.w.metaOf(delivery.PlacementCandidatesBucket, key)
+		out[node], revs[node] = c, meta.revision
+		if meta.at.After(newest) {
+			newest = meta.at
+		}
+	}
+	return out, revs, newest
+}
+
+// answersTo is, by node, each node's answer to the proposal in its `<node>.node` have.
+func (p *passer) answersTo(id string) map[string]*delivery.CandidateAnswer {
+	out := map[string]*delivery.CandidateAnswer{}
+	for key, value := range p.w.read(delivery.HaveBucket) {
+		node, _, isNode, err := delivery.ParseHaveKey(key)
+		if err != nil || !isNode {
+			continue
+		}
+		h, err := delivery.DecodeHaveNode(value)
+		if err != nil {
+			continue
+		}
+		if a, ok := h.Candidates[id]; ok {
+			out[node] = &a
+		}
+	}
+	return out
+}
+
+// placementSeat takes every open proposal one step further.
+func (p *passer) placementSeat(ctx context.Context) {
+	for _, b := range seatBuckets {
+		if p.kvs[b] == nil {
+			return
+		}
+	}
+	if p.saidProposed == nil {
+		p.saidProposed, p.intended = map[string]bool{}, map[string]map[string]map[string]bool{}
+	}
+	current, revs := p.seatPlacements()
+	ids := make([]string, 0)
+	raws := p.w.read(delivery.PlacementProposalsBucket)
+	for id := range raws {
+		ids = append(ids, id)
+	}
+	sort.Strings(ids)
+	for _, id := range ids {
+		prop, err := delivery.DecodePlacementProposal(raws[id])
+		if err != nil || prop.ID != id {
+			p.logf("the proposal %s cannot be read, so it is left: %v", id, err)
+			continue
+		}
+		p.stepProposal(ctx, prop, p.w.metaOf(delivery.PlacementProposalsBucket, id).revision, current, revs)
+	}
+}
+
+// pulse writes a bound's key with its time to live (§4): its expiry, heard on the watch as the server's delete marker,
+// is the event that ends the wait. Written again over one that stands, so its time starts anew.
+func (p *passer) pulse(ctx context.Context, key string, ttl time.Duration) {
+	kv := p.kvs[delivery.PlacementPulsesBucket]
+	_ = kv.Delete(ctx, key)
+	rev, err := kv.Create(ctx, key, []byte(`{}`), jetstream.KeyTTL(ttl))
+	if err != nil {
+		p.logf("the bound %s is not written, so its wait ends at once: %v", key, err)
+		return
+	}
+	p.w.putEntry(delivery.PlacementPulsesBucket, key, []byte(`{}`), rev, p.clock())
+}
+
+// pulsing says whether a bound's key stands.
+func (p *passer) pulsing(key string) bool { return p.w.has(delivery.PlacementPulsesBucket, key) }
+
+// deletePulses deletes every bound of a proposal.
+func (p *passer) deletePulses(ctx context.Context, id string) {
+	for key := range p.w.read(delivery.PlacementPulsesBucket) {
+		if strings.HasSuffix(key, "."+id) || strings.Contains(key, "."+id+".") {
+			if err := p.kvs[delivery.PlacementPulsesBucket].Delete(ctx, key); err == nil {
+				p.w.put(delivery.PlacementPulsesBucket, key, nil)
+			}
+		}
+	}
+}
+
+// ask raises (or raises again) a proposal's authorising ask and its bound, and answers the proposal asked.
+func (p *passer) ask(ctx context.Context, prop delivery.PlacementProposal, akey, brief string) (delivery.PlacementProposal, bool) {
+	a, err := assign.PlacementAsk(akey, prop, brief, assign.PlacementAsking(prop, p.clock()), p.clock())
+	if err != nil {
+		p.logf("the ask about the proposal %s is not written: %v", prop.ID, err)
+		return prop, false
+	}
+	p.put(ctx, delivery.AssignerAsksBucket, akey, func() ([]byte, error) { return delivery.EncodeAssignerAsk(akey, a) })
+	if pk, err := delivery.PulseAskKey(prop.ID); err == nil {
+		p.pulse(ctx, pk, a.Ask.Expires.Sub(p.clock()))
+	}
+	prop.State, prop.Ask = delivery.ProposalAsked, a.Ask.ID
+	return prop, true
+}
+
+// stepProposal takes one proposal one step further.
+func (p *passer) stepProposal(ctx context.Context, prop delivery.PlacementProposal, rev uint64, current map[string]delivery.Placement, revs map[string]uint64) {
+	if !p.saidProposed[prop.ID] && prop.State == delivery.ProposalAnswering && prop.Verdict == nil {
+		p.sayEvent(delivery.PlacementProposedEvent, delivery.PlacementEvent{Proposal: prop}, prop.ID)
+		p.saidProposed[prop.ID] = true
+	}
+	if prop.Withdrawn != "" {
+		p.endProposal(ctx, prop, prop.Withdrawn)
+		return
+	}
+	akey, _ := delivery.PlacementAskKey(prop.ID)
+	again := !prop.Again.IsZero() && (prop.Verdict == nil || prop.Again.After(prop.Verdict.At))
+	if prop.State == delivery.ProposalAsked {
+		askPulse, _ := delivery.PulseAskKey(prop.ID)
+		switch {
+		case p.answeredWith(akey, assign.OptionYes):
+			if prop.HandBack {
+				p.handBack(ctx, prop, akey, revs)
+			} else {
+				p.warranted(ctx, prop, rev, akey, current, revs)
+			}
+			return
+		case p.answeredWith(akey, assign.OptionNo):
+			p.endProposal(ctx, prop, "declined by the operator")
+			return
+		case !p.pulsing(askPulse) && !again:
+			p.endProposal(ctx, prop, "its ask expired unanswered")
+			return
+		}
+	}
+	if prop.HandBack {
+		// The operator's alone (§7): no node answers it; its ask is raised at once, and again on again.
+		if prop.State != delivery.ProposalAsked || again {
+			brief := fmt.Sprintf("%s (asked by %s): every node's placement key is deleted, %s, and each node returns to the "+
+				"controller's compositions; the history is kept", prop.Why, prop.By, strings.Join(prop.Nodes(), ", "))
+			now := p.clock().UTC()
+			prop.Verdict = &delivery.PlacementVerdict{State: delivery.VerdictPass, At: now}
+			if prop, ok := p.ask(ctx, prop, akey, brief); ok {
+				p.writeProposal(ctx, prop, rev)
+			}
+		}
+		return
+	}
+	if moved(prop, revs) {
+		p.layAgain(ctx, prop, rev, current, revs, "a key it was laid over moved since")
+		return
+	}
+	cands, candRevs, written := p.candidatesOf(prop.ID)
+	if len(prop.Must) == 0 {
+		p.mustAnswer(ctx, prop, rev, current, cands)
+		return
+	}
+	for _, node := range prop.Must {
+		if _, ok := cands[node]; !ok {
+			return // a candidate just written is not heard yet: its watch wakes the next pass
+		}
+	}
+	if written.After(prop.Written) {
+		prop.Written = written
+	}
+	pulsing := map[string]bool{}
+	for _, node := range prop.Must {
+		if k, err := delivery.PulseAnswerKey(prop.ID, node); err == nil {
+			pulsing[node] = p.pulsing(k)
+		}
+	}
+	v := judge.JudgeAnswers(prop, p.intendedOf(prop, current, cands), p.answersTo(prop.ID), candRevs, p.w.online(), pulsing, p.clock())
+	if prop.Verdict != nil && sameVerdict(*prop.Verdict, v) && !again {
+		return
+	}
+	prop.Verdict = &v
+	switch v.State {
+	case delivery.VerdictFail:
+		prop.State, prop.Ask = delivery.ProposalFailed, ""
+	case delivery.VerdictWaits:
+		prop.State, prop.Ask = delivery.ProposalAnswering, ""
+	case delivery.VerdictPass:
+		if prop.State != delivery.ProposalAsked || again {
+			var ok bool
+			if prop, ok = p.ask(ctx, prop, akey, judge.Brief(prop, v)); !ok {
+				return
+			}
+			if again {
+				prop.Words = "judged and asked again (again)"
+			}
+		}
+	}
+	if p.writeProposal(ctx, prop, rev) {
+		p.sayEvent(delivery.PlacementJudgedEvent, delivery.PlacementEvent{Proposal: prop},
+			fmt.Sprintf("%s.judged.%d", prop.ID, v.At.UnixNano()))
+	}
+}
+
+// sameVerdict says two verdicts say the same, their time aside.
+func sameVerdict(a, b delivery.PlacementVerdict) bool {
+	a.At, b.At = time.Time{}, time.Time{}
+	return reflect.DeepEqual(a, b)
+}
+
+// moved says whether a key the proposal changes is no longer at the revision it was laid over.
+func moved(prop delivery.PlacementProposal, revs map[string]uint64) bool {
+	for node, base := range prop.Base {
+		if revs[node] != base {
+			return true
+		}
+	}
+	return false
+}
+
+// intended is, by proposal and the revisions it was laid over, what Intended computed, kept while this process runs.
+func (p *passer) intendedOf(prop delivery.PlacementProposal, current map[string]delivery.Placement, cands map[string]delivery.PlacementCandidate) map[string]map[string]bool {
+	key := fmt.Sprint(prop.ID, prop.Base)
+	if got, ok := p.intended[key]; ok {
+		return got
+	}
+	got, _, _ := p.compute(prop, current, cands)
+	p.intended[key] = got
+	return got
+}
+
+// compute composes every node with the current placement and with the proposal laid over it (judge.Intended).
+func (p *passer) compute(prop delivery.PlacementProposal, current map[string]delivery.Placement, cands map[string]delivery.PlacementCandidate) (map[string]map[string]bool, []string, []string) {
+	laid := map[string]*delivery.Placement{}
+	for _, node := range prop.Nodes() {
+		if c, ok := cands[node]; ok && !c.Reached {
+			laid[node] = c.Placement
+		}
+	}
+	get := kvGetter(p.kvs[delivery.ManifestsBucket])
+	r := worldReader{w: p.w, manifests: get}
+	var now, with *compose.Input
+	if in, err := frombus.Input(context.Background(), r, frombus.Mesh{}, frombus.Scope{Every: true}); err == nil {
+		now = &in
+	}
+	if in, err := frombus.Input(context.Background(), r, frombus.Mesh{}, frombus.Scope{Every: true, Placements: laid}); err == nil {
+		with = &in
+	}
+	nodes := map[string]bool{}
+	for n := range current {
+		nodes[n] = true
+	}
+	if records, err := r.Records(context.Background()); err == nil {
+		for n := range records {
+			nodes[n] = true
+		}
+	}
+	names := make([]string, 0, len(nodes))
+	for n := range nodes {
+		names = append(names, n)
+	}
+	fps := map[string]string{}
+	for name, m := range p.w.trunk() {
+		if m.FP2 != "" {
+			fps[name] = m.FP2
+		}
+	}
+	return judge.Intended(now, with, current, laid, names, fps)
+}
+
+// mustAnswer finds the nodes the proposal must hear from (§3), writes a reached candidate for each whose key it does not
+// change, and writes them into the proposal.
+func (p *passer) mustAnswer(ctx context.Context, prop delivery.PlacementProposal, rev uint64, current map[string]delivery.Placement, cands map[string]delivery.PlacementCandidate) {
+	for _, node := range prop.Nodes() {
+		if _, ok := cands[node]; !ok {
+			return // the verbs write the candidates before the proposal: wait to hear them
+		}
+	}
+	intended, must, notes := p.compute(prop, current, cands)
+	p.intended[fmt.Sprint(prop.ID, prop.Base)] = intended
+	for _, node := range must {
+		if _, ok := cands[node]; ok {
+			continue
+		}
+		key, err := delivery.PlacementCandidateKey(prop.ID, node)
+		if err != nil {
+			continue
+		}
+		c := delivery.PlacementCandidate{Proposal: prop.ID, Reached: true}
+		if pl, ok := current[node]; ok {
+			c.Placement = &pl
+		}
+		p.put(ctx, delivery.PlacementCandidatesBucket, key, func() ([]byte, error) { return delivery.EncodePlacementCandidate(c) })
+	}
+	for _, node := range must {
+		if k, err := delivery.PulseAnswerKey(prop.ID, node); err == nil {
+			p.pulse(ctx, k, judge.AnswerBound)
+		}
+	}
+	prop.Must = must
+	if len(notes) > 0 {
+		prop.Words = strings.TrimPrefix(prop.Words+"; "+strings.Join(notes, "; "), "; ")
+	}
+	p.writeProposal(ctx, prop, rev)
+}
+
+// layAgain lays a proposal over the keys as they stand now (§5: a key moved): its candidates are written again, the
+// nodes that must answer found again, and it is judged and asked again; a proposal that no longer lays ends.
+func (p *passer) layAgain(ctx context.Context, prop delivery.PlacementProposal, rev uint64, current map[string]delivery.Placement, revs map[string]uint64, why string) {
+	held, recorded := p.lays(ctx)
+	again, laid, findings := assign.Propose(assign.ProposeIn{ID: prop.ID, By: prop.By, Why: prop.Why, At: prop.At, Changes: prop.Changes,
+		Current: current, Revisions: revs, Held: held, Recorded: recorded,
+		Seed: prop.Seed, ExportDigest: prop.ExportDigest, Leased: p.w.handedAway()})
+	if len(findings) > 0 {
+		p.endProposal(ctx, prop, why+", and laid over the keys now it is refused: "+strings.Join(findings, "; "))
+		return
+	}
+	p.deleteCandidates(ctx, prop.ID)
+	p.deletePulses(ctx, prop.ID)
+	for _, node := range again.Nodes() {
+		key, _ := delivery.PlacementCandidateKey(prop.ID, node)
+		c := delivery.PlacementCandidate{Proposal: prop.ID, Placement: laid[node]}
+		p.put(ctx, delivery.PlacementCandidatesBucket, key, func() ([]byte, error) { return delivery.EncodePlacementCandidate(c) })
+	}
+	again.Written, again.Words = p.clock().UTC(), why+": laid again over the keys as they stand, to be judged and asked again"
+	p.seat.forget(prop.ID)
+	p.writeProposal(ctx, again, rev)
+}
+
+// lays is what a proposal is checked against, as the verbs check it: the modules the indexer holds, by key, and the
+// nodes with a record.
+func (p *passer) lays(ctx context.Context) (func(string) bool, func(string) bool) {
+	held := map[string]bool{}
+	for key := range p.w.read(delivery.ModulesBucket) {
+		if name, err := delivery.ParseModulesKey(key); err == nil {
+			held[name] = true
+		}
+	}
+	records, _ := worldReader{w: p.w}.Records(ctx)
+	return func(m string) bool { return held[m] }, func(n string) bool { _, ok := records[n]; return ok }
+}
+
+// warranted writes an approved proposal (§5): for the seed, after the export is read again and found unchanged (§7);
+// each changed key by compare-and-set at the revision it was laid over; then the warrant recorded, the candidates and the
+// proposal deleted, placement-changed said, and the controller kept in step (§8).
+func (p *passer) warranted(ctx context.Context, prop delivery.PlacementProposal, rev uint64, akey string, current map[string]delivery.Placement, revs map[string]uint64) {
+	if err := p.performs(akey, assign.PlacementAct(prop)); err != nil {
+		p.endProposal(ctx, prop, "its warrant does not bind these changes, so nothing is written: "+err.Error())
+		return
+	}
+	answer, _ := p.w.answer(akey)
+	if prop.Seed {
+		if p.seat == nil {
+			return
+		}
+		c := p.seat.exportOf(prop.ID)
+		switch {
+		case c.running:
+			return // its answer wakes the next pass
+		case c.err != "":
+			if words := "the export cannot be read again at the warrant: " + c.err; prop.Words != words {
+				prop.Words = words
+				p.writeProposal(ctx, prop, rev)
+			}
+			return
+		case delivery.ExportDigest(c.export) != prop.ExportDigest:
+			p.endProposal(ctx, prop, "the controller's export changed since the seed was proposed: the new export is proposed as the seed")
+			p.proposeSeed(ctx, prop, c.export)
+			return
+		}
+	}
+	if moved(prop, revs) {
+		p.layAgain(ctx, prop, rev, current, revs, "a key moved since it was approved, so its warrant is spent")
+		return
+	}
+	cands, _, _ := p.candidatesOf(prop.ID)
+	laid := map[string]*delivery.Placement{}
+	for _, node := range prop.Nodes() {
+		laid[node] = cands[node].Placement
+	}
+	writes, err := assign.Writes(prop, laid)
+	if err != nil {
+		p.logf("the proposal %s cannot be written: %v", prop.ID, err)
+		return
+	}
+	kv := p.kvs[delivery.PlacementBucket]
+	var changes []delivery.PlacementChange
+	writtenLaid := map[string]*delivery.Placement{}
+	after := maps.Clone(current)
+	afterRevs := maps.Clone(revs)
+	for _, w := range writes {
+		var rev2 uint64
+		var err error
+		switch {
+		case w.Value == nil:
+			err = kv.Delete(ctx, w.Key, jetstream.LastRevision(w.Base))
+		default:
+			raw, encErr := delivery.EncodePlacement(*w.Value)
+			if encErr != nil {
+				err = encErr
+			} else if w.Base == 0 {
+				rev2, err = kv.Create(ctx, w.Key, raw)
+			} else {
+				rev2, err = kv.Update(ctx, w.Key, raw, w.Base)
+			}
+		}
+		if err != nil {
+			// Another writer came first (a hand-back): what is written stands and is followed through; the rest is laid
+			// again over the keys as this write left them.
+			p.logf("placement %s is not written at revision %d (%v): the rest of the proposal %s is laid again", w.Key, w.Base, err, prop.ID)
+			p.followWrite(prop, answer, changes, current, writtenLaid)
+			if rest, ok := assign.Rest(prop, writtenLaid); ok {
+				p.layAgain(ctx, rest, rev, after, afterRevs, "a key moved while it was written, after "+strings.Join(sortedNodes(writtenLaid), ", ")+" were")
+			} else {
+				p.endProposal(ctx, prop, "a key moved while it was written: "+err.Error())
+			}
+			return
+		}
+		before := current[w.Node]
+		now := delivery.Placement{Node: w.Node}
+		if w.Value != nil {
+			now = *w.Value
+			after[w.Node] = *w.Value
+		} else {
+			delete(after, w.Node)
+		}
+		afterRevs[w.Node] = rev2
+		c := delivery.ChangeOf(before, now)
+		c.Before, c.After = w.Base, rev2
+		changes = append(changes, c)
+		writtenLaid[w.Node] = w.Value
+	}
+	p.deleteCandidates(ctx, prop.ID)
+	p.deletePulses(ctx, prop.ID)
+	_ = p.kvs[delivery.PlacementProposalsBucket].Delete(ctx, prop.ID)
+	p.w.put(delivery.PlacementProposalsBucket, prop.ID, nil)
+	p.followWrite(prop, answer, changes, current, writtenLaid)
+}
+
+// followWrite follows the keys a warrant wrote: the warrant recorded, placement-changed said, and, until the lease
+// write, the controller's assignments kept in step for them (§8). The seed calls no controller verb: it is what the
+// controller holds already (§9).
+func (p *passer) followWrite(prop delivery.PlacementProposal, answer delivery.Answer, changes []delivery.PlacementChange,
+	before map[string]delivery.Placement, written map[string]*delivery.Placement) {
+	if len(changes) == 0 {
+		return
+	}
+	p.seat.record(answer.Warrant)
+	p.sayChanged(prop, answer, changes)
+	if p.seat != nil && !p.w.handedAway() && !prop.Seed {
+		p.seat.callAll(assign.ControllerCalls(before, written, prop.ID, answer.Warrant))
+	}
+}
+
+func sortedNodes(m map[string]*delivery.Placement) []string {
+	out := make([]string, 0, len(m))
+	for n := range m {
+		out = append(out, n)
+	}
+	sort.Strings(out)
+	return out
+}
+
+// handBack deletes every key on the operator's warrant (§7) at the revision the hand-back read, records it in the
+// controller's hand-act log and says placement-changed; every node returns to the controller's compositions. A key moved
+// since ends it, and the operator hands back again.
+func (p *passer) handBack(ctx context.Context, prop delivery.PlacementProposal, akey string, revs map[string]uint64) {
+	if err := p.performs(akey, assign.PlacementAct(prop)); err != nil {
+		p.endProposal(ctx, prop, "its warrant does not bind this hand-back, so nothing is deleted: "+err.Error())
+		return
+	}
+	answer, _ := p.w.answer(akey)
+	current, _ := p.seatPlacements()
+	var changes []delivery.PlacementChange
+	for _, node := range prop.Nodes() {
+		key, _ := delivery.PlacementKey(node)
+		if err := p.kvs[delivery.PlacementBucket].Delete(ctx, key, jetstream.LastRevision(prop.Base[node])); err != nil {
+			p.sayChanged(prop, answer, changes)
+			p.endProposal(ctx, prop, fmt.Sprintf("%s moved since the hand-back was asked (%v): hand back again", key, err))
+			return
+		}
+		c := delivery.ChangeOf(current[node], delivery.Placement{Node: node})
+		c.Before = prop.Base[node]
+		changes = append(changes, c)
+	}
+	if p.seat != nil {
+		p.seat.handAct(prop)
+	}
+	p.seat.record(answer.Warrant)
+	_ = p.kvs[delivery.PlacementProposalsBucket].Delete(ctx, prop.ID)
+	p.w.put(delivery.PlacementProposalsBucket, prop.ID, nil)
+	p.deletePulses(ctx, prop.ID)
+	p.sayChanged(prop, answer, changes)
+}
+
+// sayChanged says placement-changed for the keys written.
+func (p *passer) sayChanged(prop delivery.PlacementProposal, answer delivery.Answer, changes []delivery.PlacementChange) {
+	if len(changes) == 0 {
+		return
+	}
+	at := p.clock().UTC()
+	if _, when, ok := strings.Cut(answer.Warrant, "@"); ok {
+		if t, err := time.Parse(time.RFC3339Nano, when); err == nil {
+			at = t
+		}
+	}
+	delivery.SortChanges(changes)
+	p.sayEvent(delivery.PlacementChangedEvent, delivery.PlacementEvent{Proposal: prop, Nodes: changes,
+		Warrant: &delivery.PlacementWarrant{Warrant: answer.Warrant, Words: answer.Words, At: at}}, prop.ID+".changed")
+}
+
+// proposeSeed proposes an export as the seed again, by the same proposer and why.
+func (p *passer) proposeSeed(ctx context.Context, was delivery.PlacementProposal, export map[string]delivery.Placement) {
+	held, recorded := p.lays(ctx)
+	now := p.clock()
+	seed, laid, findings := assign.Propose(assign.ProposeIn{ID: delivery.NewProposalID(now), By: was.By, Why: was.Why, At: now,
+		Changes: assign.SeedChanges(export), Current: map[string]delivery.Placement{}, Revisions: map[string]uint64{},
+		Held: held, Recorded: recorded, Seed: true, ExportDigest: delivery.ExportDigest(export), Leased: p.w.handedAway()})
+	if len(findings) > 0 {
+		p.logf("the new export is not proposed as the seed: %s", strings.Join(findings, "; "))
+		return
+	}
+	for _, node := range seed.Nodes() {
+		key, _ := delivery.PlacementCandidateKey(seed.ID, node)
+		c := delivery.PlacementCandidate{Proposal: seed.ID, Placement: laid[node]}
+		p.put(ctx, delivery.PlacementCandidatesBucket, key, func() ([]byte, error) { return delivery.EncodePlacementCandidate(c) })
+	}
+	seed.Written = now.UTC()
+	p.writeProposal(ctx, seed, 0)
+}
+
+// endProposal ends a proposal: its ask, its candidates and its key deleted, and placement-withdrawn said carrying it
+// whole with why it ended.
+func (p *passer) endProposal(ctx context.Context, prop delivery.PlacementProposal, why string) {
+	if akey, err := delivery.PlacementAskKey(prop.ID); err == nil && p.w.has(delivery.AssignerAsksBucket, akey) {
+		if err := p.kvs[delivery.AssignerAsksBucket].Delete(ctx, akey); err == nil {
+			p.w.put(delivery.AssignerAsksBucket, akey, nil)
+		}
+	}
+	p.deleteCandidates(ctx, prop.ID)
+	p.deletePulses(ctx, prop.ID)
+	if err := p.kvs[delivery.PlacementProposalsBucket].Delete(ctx, prop.ID); err != nil && !errors.Is(err, context.Canceled) {
+		p.logf("the proposal %s is not deleted, and is ended at the next pass: %v", prop.ID, err)
+		return
+	}
+	p.w.put(delivery.PlacementProposalsBucket, prop.ID, nil)
+	p.seat.forget(prop.ID)
+	p.logf("the proposal %s ends: %s", prop.ID, why)
+	p.sayEvent(delivery.PlacementWithdrawnEvent, delivery.PlacementEvent{Proposal: prop, Ended: why}, prop.ID+".withdrawn")
+}
+
+// deleteCandidates deletes every candidate of a proposal.
+func (p *passer) deleteCandidates(ctx context.Context, id string) {
+	for key := range p.w.read(delivery.PlacementCandidatesBucket) {
+		if pid, _, err := delivery.ParsePlacementCandidateKey(key); err == nil && pid == id {
+			if err := p.kvs[delivery.PlacementCandidatesBucket].Delete(ctx, key); err == nil {
+				p.w.put(delivery.PlacementCandidatesBucket, key, nil)
+			}
+		}
+	}
+}
+
+// writeProposal writes a proposal over the revision the pass read, by compare-and-set: a verb that marked it meanwhile
+// (withdraw, again) wins, and the next pass reads that. It says whether it wrote.
+func (p *passer) writeProposal(ctx context.Context, prop delivery.PlacementProposal, rev uint64) bool {
+	raw, err := delivery.EncodePlacementProposal(prop)
+	if err != nil {
+		p.logf("the proposal %s is not written: %v", prop.ID, err)
+		return false
+	}
+	kv := p.kvs[delivery.PlacementProposalsBucket]
+	var at uint64
+	if rev == 0 {
+		at, err = kv.Create(ctx, prop.ID, raw)
+	} else {
+		at, err = kv.Update(ctx, prop.ID, raw, rev)
+	}
+	if err != nil {
+		if !errors.Is(err, context.Canceled) {
+			p.logf("the proposal %s is not written, and is taken further at the next pass: %v", prop.ID, err)
+		}
+		return false
+	}
+	p.w.putEntry(delivery.PlacementProposalsBucket, prop.ID, raw, at, p.clock())
+	return true
+}
+
+// say says one of the seat's events, said in the journal when the bus refuses it.
+func (p *passer) sayEvent(event string, body delivery.PlacementEvent, id string) {
+	if p.publish == nil {
+		return
+	}
+	if err := p.publish(event, body, id); err != nil {
+		p.logf("%s of %s is not said: %v", event, body.Proposal.ID, err)
+	}
+}

modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/seat_tools.go

@@ -0,0 +1,543 @@
+package main
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"sort"
+	"strings"
+	"time"
+
+	stdio "git.novox.be/novox/mesh-sdk/go"
+	"git.novox.be/novox/mesh-sdk/go/buscompose"
+	"git.novox.be/novox/mesh-sdk/go/catalogue"
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+
+	"mesh-delivery-assigner/internal/assign"
+)
+
+// The seat mesh-placement's seven verbs (novox/hq ADR 0567 §10), served through the tool runner beside the put tools: a
+// process never serves (ADR 0436). They read every state the seat keeps and write what a person asks of it: a proposal
+// and its candidates (propose, adopt), a proposal marked to end (withdraw) or to be judged again (again), and the keys
+// deleted (hand-back). Everything that follows a proposal — composing it, judging the answers, the ask, the write at the
+// warrant and the seat's events on its stream — is the assigner's process's (seat.go), started by these writes.
+
+// seatStore is what the seat's verbs need of the states: the runtime's, or a test's.
+type seatStore interface {
+	store
+	del(state, key string) error
+	history(state, key string) ([]stdio.StateRevision, error)
+}
+
+func (runtimeStore) del(state, key string) error { return stdio.State(state).Delete(key) }
+
+func (runtimeStore) history(state, key string) ([]stdio.StateRevision, error) {
+	return stdio.State(state).History(key)
+}
+
+// The states the verbs read, as the runtime names them: the seat's own by their local names, the others'
+// `<module>.<state>`.
+const (
+	modulesState = delivery.IndexerModule + ".modules"
+	haveState    = "node-engine.have"
+)
+
+// seatTools serves the seat's verbs over a store, asking the controller through ask (stdio.Ask, or a test's).
+type seatTools struct {
+	st  seatStore
+	ask func(key string, body any) (json.RawMessage, error)
+	now func() time.Time
+}
+
+func newSeatTools(st seatStore, ask func(string, any) (json.RawMessage, error)) *seatTools {
+	return &seatTools{st: st, ask: ask, now: time.Now}
+}
+
+// keyed is one placement key as a verb answers it.
+type keyed struct {
+	Placement delivery.Placement `json:"placement"`
+	Revision  uint64             `json:"revision"`
+}
+
+// placements reads every node's placement and its key's revision.
+func (s *seatTools) placements() (map[string]delivery.Placement, map[string]uint64, error) {
+	keys, err := s.st.keys(delivery.PlacementState)
+	if err != nil {
+		return nil, nil, fmt.Errorf("placement cannot be listed: %w", err)
+	}
+	out, revs := map[string]delivery.Placement{}, map[string]uint64{}
+	for _, key := range keys {
+		node, err := delivery.ParsePlacementKey(key)
+		if err != nil {
+			continue
+		}
+		raw, rev, found, err := s.st.get(delivery.PlacementState, key)
+		if err != nil {
+			return nil, nil, fmt.Errorf("placement of %s cannot be read: %w", node, err)
+		}
+		if !found {
+			continue
+		}
+		p, err := delivery.DecodePlacement(raw)
+		if err != nil {
+			return nil, nil, fmt.Errorf("placement of %s cannot be read: %w", node, err)
+		}
+		out[node], revs[node] = p, rev
+	}
+	return out, revs, nil
+}
+
+// lays is what a proposal is checked against: the modules the indexer holds and the nodes with a record.
+func (s *seatTools) lays() (func(string) bool, func(string) bool, error) {
+	mods, err := s.st.keys(modulesState)
+	if err != nil {
+		return nil, nil, fmt.Errorf("the indexer's modules cannot be listed: %w", err)
+	}
+	held := map[string]bool{}
+	for _, k := range mods {
+		if name, err := delivery.ParseModulesKey(k); err == nil {
+			held[name] = true
+		}
+	}
+	haves, err := s.st.keys(haveState)
+	if err != nil {
+		return nil, nil, fmt.Errorf("the nodes' records cannot be listed: %w", err)
+	}
+	recorded := map[string]bool{}
+	for _, k := range haves {
+		node, _, isNode, err := delivery.ParseHaveKey(k)
+		if err != nil || !isNode {
+			continue
+		}
+		if raw, _, found, err := s.st.get(haveState, k); err == nil && found {
+			if h, err := delivery.DecodeHaveNode(raw); err == nil && h.Record != nil {
+				recorded[node] = true
+			}
+		}
+	}
+	return func(m string) bool { return held[m] }, func(n string) bool { return recorded[n] }, nil
+}
+
+// proposal reads one open proposal.
+func (s *seatTools) proposal(id string) (delivery.PlacementProposal, error) {
+	if err := delivery.CheckProposalID(id); err != nil {
+		return delivery.PlacementProposal{}, err
+	}
+	raw, _, found, err := s.st.get(delivery.PlacementProposalsState, id)
+	if err != nil {
+		return delivery.PlacementProposal{}, fmt.Errorf("the proposal %s cannot be read: %w", id, err)
+	}
+	if !found {
+		return delivery.PlacementProposal{}, fmt.Errorf("no proposal %s is open: mesh-placement.proposals lists those that are", id)
+	}
+	return delivery.DecodePlacementProposal(raw)
+}
+
+// write writes a proposal laid by assign.Propose: each candidate, then the proposal, whose write the assigner's process
+// takes as the event to compose and judge it.
+func (s *seatTools) write(p delivery.PlacementProposal, laid map[string]*delivery.Placement) error {
+	p.Written = s.now().UTC()
+	for _, node := range p.Nodes() {
+		key, err := delivery.PlacementCandidateKey(p.ID, node)
+		if err != nil {
+			return err
+		}
+		raw, err := delivery.EncodePlacementCandidate(delivery.PlacementCandidate{Proposal: p.ID, Placement: laid[node]})
+		if err != nil {
+			return err
+		}
+		if err := s.st.put(delivery.PlacementCandidatesState, key, raw); err != nil {
+			return fmt.Errorf("the candidate %s is not written: %w", key, err)
+		}
+	}
+	raw, err := delivery.EncodePlacementProposal(p)
+	if err != nil {
+		return err
+	}
+	if err := s.st.put(delivery.PlacementProposalsState, p.ID, raw); err != nil {
+		return fmt.Errorf("the proposal %s is not written: %w", p.ID, err)
+	}
+	return nil
+}
+
+// proposed is what propose and adopt answer.
+type proposed struct {
+	Proposal delivery.PlacementProposal `json:"proposal"`
+	Follow   string                     `json:"follow"`
+}
+
+func followProposal(id string) string {
+	return fmt.Sprintf("the nodes it touches answer it; mesh-placement.proposals with id %q says where it stands, and the "+
+		"operator is asked to approve it once its verdict passes", id)
+}
+
+// changesOf reads propose's changes: a JSON array, given as one or as its text.
+func changesOf(v any) ([]delivery.PlacementProposalChange, error) {
+	var raw []byte
+	switch c := v.(type) {
+	case string:
+		raw = []byte(c)
+	case nil:
+		return nil, errors.New("propose names its changes")
+	default:
+		var err error
+		if raw, err = json.Marshal(c); err != nil {
+			return nil, err
+		}
+	}
+	var out []delivery.PlacementProposalChange
+	dec := json.NewDecoder(strings.NewReader(string(raw)))
+	dec.DisallowUnknownFields()
+	if err := dec.Decode(&out); err != nil {
+		return nil, fmt.Errorf("the changes are no list of changes: %w", err)
+	}
+	return out, nil
+}
+
+// doPropose is the verb propose (§2).
+func (s *seatTools) doPropose(args map[string]any, by string) (any, error) {
+	changes, err := changesOf(args["changes"])
+	if err != nil {
+		return nil, err
+	}
+	for _, c := range changes {
+		if c.Op == delivery.OpSeed {
+			return nil, errors.New("the seed is adopt's alone: propose takes place, take-off, pin, unpin, hold, unhold, decide and config")
+		}
+	}
+	current, revs, err := s.placements()
+	if err != nil {
+		return nil, err
+	}
+	held, recorded, err := s.lays()
+	if err != nil {
+		return nil, err
+	}
+	now := s.now()
+	p, laid, findings := assign.Propose(assign.ProposeIn{ID: delivery.NewProposalID(now), By: by, Why: arg(args, "why"), At: now,
+		Changes: changes, Current: current, Revisions: revs, Held: held, Recorded: recorded, Leased: s.leased()})
+	if len(findings) > 0 {
+		return nil, fmt.Errorf("the proposal is refused: %s", strings.Join(findings, "; "))
+	}
+	if err := s.write(p, laid); err != nil {
+		return nil, err
+	}
+	return proposed{Proposal: p, Follow: followProposal(p.ID)}, nil
+}
+
+// doWithdraw is the verb withdraw (§2): the proposal is marked, and the assigner deletes it and its candidates and says
+// placement-withdrawn carrying it whole.
+func (s *seatTools) doWithdraw(args map[string]any, by string) (any, error) {
+	why := arg(args, "why")
+	if why == "" {
+		return nil, errors.New("withdraw says why: it is kept in the event that ends the proposal")
+	}
+	p, err := s.proposal(arg(args, "id"))
+	if err != nil {
+		return nil, err
+	}
+	p.Withdrawn = fmt.Sprintf("withdrawn by %s: %s", by, why)
+	raw, err := delivery.EncodePlacementProposal(p)
+	if err != nil {
+		return nil, err
+	}
+	if err := s.st.put(delivery.PlacementProposalsState, p.ID, raw); err != nil {
+		return nil, fmt.Errorf("the proposal %s is not withdrawn: %w", p.ID, err)
+	}
+	return map[string]any{"proposal": p.ID, "withdrawn": p.Withdrawn}, nil
+}
+
+// doAgain is the verb again (§10): the proposal is marked, and the assigner judges it now and raises its ask again
+// when its verdict passes.
+func (s *seatTools) doAgain(args map[string]any) (any, error) {
+	p, err := s.proposal(arg(args, "id"))
+	if err != nil {
+		return nil, err
+	}
+	p.Again = s.now().UTC()
+	raw, err := delivery.EncodePlacementProposal(p)
+	if err != nil {
+		return nil, err
+	}
+	if err := s.st.put(delivery.PlacementProposalsState, p.ID, raw); err != nil {
+		return nil, fmt.Errorf("the proposal %s is not asked again: %w", p.ID, err)
+	}
+	return map[string]any{"proposal": p.ID, "again": p.Again, "follow": followProposal(p.ID)}, nil
+}
+
+// exportCall is the controller's verb the seed is read from, by request and reply on its seat (§7).
+const exportCall = "seat:" + catalogue.ControllerSeatName + ".placement-export"
+
+// doAdopt is the verb adopt (§7): the controller's export proposed whole as the seed.
+func (s *seatTools) doAdopt(args map[string]any, by string) (any, error) {
+	current, _, err := s.placements()
+	if err != nil {
+		return nil, err
+	}
+	if len(current) > 0 {
+		return nil, fmt.Errorf("placement is taken over already (%d keys): propose a change instead, or hand it back first", len(current))
+	}
+	if ids, err := s.st.keys(delivery.PlacementProposalsState); err == nil {
+		for _, id := range ids {
+			if p, err := s.proposal(id); err == nil && p.Seed {
+				return nil, fmt.Errorf("the seed %s is open: withdraw it first, or answer its ask", id)
+			}
+		}
+	}
+	raw, err := s.ask(exportCall, map[string]any{})
+	if err != nil {
+		return nil, fmt.Errorf("the controller's placement-export did not answer: %w", err)
+	}
+	export, err := assign.ExportOf(raw)
+	if err != nil {
+		return nil, err
+	}
+	held, recorded, err := s.lays()
+	if err != nil {
+		return nil, err
+	}
+	now := s.now()
+	p, laid, findings := assign.Propose(assign.ProposeIn{ID: delivery.NewProposalID(now), By: by, Why: arg(args, "why"), At: now,
+		Changes: assign.SeedChanges(export), Current: map[string]delivery.Placement{}, Revisions: map[string]uint64{},
+		Held: held, Recorded: recorded, Seed: true, ExportDigest: delivery.ExportDigest(export), Leased: s.leased()})
+	if len(findings) > 0 {
+		return nil, fmt.Errorf("the seed is refused: %s", strings.Join(findings, "; "))
+	}
+	if err := s.write(p, laid); err != nil {
+		return nil, err
+	}
+	return proposed{Proposal: p, Follow: followProposal(p.ID)}, nil
+}
+
+// leased says the controller's lease is handed away (mesh-sdk buscompose.LeaseHandedAway, ADR 0561 §3; issue 774): the lease
+// write of ADR 0547 that ends keeping the controller in step (ADR 0567 §8). A lease not read, a controller's, expired or
+// unreadable, is not handed away.
+func (s *seatTools) leased() bool {
+	raw, _, found, err := s.st.get(buscompose.ControllerLease, buscompose.ControllerLeaseKey)
+	away, _ := buscompose.LeaseHandedAway(raw, found && raw != nil, err)
+	return away
+}
+
+// handActCall records a hand act in the controller's hand-act log.
+const handActCall = "seat:" + catalogue.ControllerSeatName + ".hand-act"
+
+// doHandBack is the verb hand-back (§7): the operator's alone, so it is asked as a proposal is. It writes a hand-back
+// proposal naming every key at its revision; the assigner raises its authorising ask and, on its warrant, deletes the keys,
+// records the hand act and says placement-changed; every node returns to the controller's compositions.
+func (s *seatTools) doHandBack(args map[string]any, by string) (any, error) {
+	if s.leased() {
+		return nil, errors.New("placement is the mesh's alone since the lease write: there is no controller to hand it back to")
+	}
+	why := arg(args, "why")
+	if why == "" {
+		return nil, errors.New("hand-back says why: it is recorded with the hand act")
+	}
+	if by == "" {
+		return nil, errors.New("the runtime names no caller: a hand-back is made by someone")
+	}
+	_, revs, err := s.placements()
+	if err != nil {
+		return nil, err
+	}
+	if len(revs) == 0 {
+		return nil, errors.New("there is no placement key to hand back")
+	}
+	now := s.now()
+	p := delivery.PlacementProposal{ID: delivery.NewProposalID(now), By: by, Why: why, At: now.UTC(), Written: now.UTC(),
+		HandBack: true, Base: revs, State: delivery.ProposalAnswering}
+	raw, err := delivery.EncodePlacementProposal(p)
+	if err != nil {
+		return nil, err
+	}
+	if err := s.st.put(delivery.PlacementProposalsState, p.ID, raw); err != nil {
+		return nil, fmt.Errorf("the hand-back is not written: %w", err)
+	}
+	return proposed{Proposal: p, Follow: "the operator is asked to approve it; on the warrant every key is deleted and each " +
+		"node returns to the controller's compositions"}, nil
+}
+
+// placementAnswer is what the verb placement answers.
+type placementAnswer struct {
+	Keys    map[string]keyed `json:"keys,omitempty"`
+	Nodes   []string         `json:"nodes,omitempty"`
+	Count   int              `json:"count"`
+	History int              `json:"history-per-key"`
+	Changes []historyEntry   `json:"changes,omitempty"`
+	Older   string           `json:"older,omitempty"`
+}
+
+// historyEntry is one change of a key in the state's revisions.
+type historyEntry struct {
+	Node     string                   `json:"node"`
+	Revision uint64                   `json:"revision"`
+	At       time.Time                `json:"at"`
+	Change   delivery.PlacementChange `json:"change"`
+	Deleted  bool                     `json:"deleted,omitempty"`
+}
+
+// doPlacement is the verb placement (§10, §6): one node's key, one module's nodes, or every key; with history, the
+// changes in order from the revisions the state keeps.
+func (s *seatTools) doPlacement(args map[string]any) (any, error) {
+	all, revs, err := s.placements()
+	if err != nil {
+		return nil, err
+	}
+	node, module := arg(args, "node"), arg(args, "module")
+	out := placementAnswer{Keys: map[string]keyed{}, Count: len(all), History: delivery.PlacementHistory}
+	for n, p := range all {
+		if node != "" && n != node {
+			continue
+		}
+		if module != "" && !strings.Contains(" "+strings.Join(p.Assigned(), " ")+" ", " "+module+" ") {
+			continue
+		}
+		out.Keys[n] = keyed{Placement: p, Revision: revs[n]}
+		out.Nodes = append(out.Nodes, n)
+	}
+	sort.Strings(out.Nodes)
+	if node != "" && len(out.Keys) == 0 && arg(args, "history") != "true" {
+		return nil, fmt.Errorf("%s has no placement key", node)
+	}
+	if arg(args, "history") != "true" {
+		return out, nil
+	}
+	nodes := out.Nodes
+	if node != "" {
+		nodes = []string{node}
+	} else if module == "" {
+		nodes = nil
+		for n := range all {
+			nodes = append(nodes, n)
+		}
+		sort.Strings(nodes)
+	}
+	for _, n := range nodes {
+		key, err := delivery.PlacementKey(n)
+		if err != nil {
+			return nil, err
+		}
+		revisions, err := s.st.history(delivery.PlacementState, key)
+		if err != nil {
+			return nil, fmt.Errorf("the history of %s cannot be read: %w", key, err)
+		}
+		var before delivery.Placement
+		for _, r := range revisions {
+			e := historyEntry{Node: n, Revision: r.Revision, At: r.At}
+			after := delivery.Placement{}
+			if r.Op == "" || r.Op == "put" || r.Op == "PUT" {
+				if p, err := delivery.DecodePlacement(r.Value); err == nil {
+					after = p
+				}
+			} else {
+				e.Deleted = true
+			}
+			e.Change = delivery.ChangeOf(before, after)
+			e.Change.Before, e.Change.After = 0, r.Revision
+			before = after
+			if module != "" && !strings.Contains(" "+strings.Join(append(append(e.Change.Added, e.Change.Removed...), e.Change.Changed...), " ")+" ", " "+module+" ") {
+				continue
+			}
+			out.Changes = append(out.Changes, e)
+		}
+	}
+	out.Older = fmt.Sprintf("the state keeps %d revisions of each key; an older change is in its placement-changed event on "+
+		"the assigner's stream %s, kept %d days", delivery.PlacementHistory, delivery.PlacementStream, delivery.PlacementStreamDays)
+	return out, nil
+}
+
+// openProposal is one open proposal as the verb proposals answers it: the proposal (its changes, base revisions,
+// verdict with the differences and the answers it judged, its ask), its candidates by node with their revisions, and
+// every node's answer now.
+type openProposal struct {
+	Proposal   delivery.PlacementProposal          `json:"proposal"`
+	Candidates map[string]uint64                   `json:"candidates"`
+	Answers    map[string]delivery.CandidateAnswer `json:"answers,omitempty"`
+}
+
+// doProposals is the verb proposals (§10).
+func (s *seatTools) doProposals(args map[string]any) (any, error) {
+	ids, err := s.st.keys(delivery.PlacementProposalsState)
+	if err != nil {
+		return nil, fmt.Errorf("the proposals cannot be listed: %w", err)
+	}
+	cands, err := s.st.keys(delivery.PlacementCandidatesState)
+	if err != nil {
+		return nil, fmt.Errorf("the candidates cannot be listed: %w", err)
+	}
+	haves, err := s.st.keys(haveState)
+	if err != nil {
+		return nil, fmt.Errorf("the nodes' haves cannot be listed: %w", err)
+	}
+	answers := map[string]map[string]delivery.CandidateAnswer{} // by proposal, then node
+	for _, k := range haves {
+		node, _, isNode, err := delivery.ParseHaveKey(k)
+		if err != nil || !isNode {
+			continue
+		}
+		raw, _, found, err := s.st.get(haveState, k)
+		if err != nil || !found {
+			continue
+		}
+		h, err := delivery.DecodeHaveNode(raw)
+		if err != nil {
+			continue
+		}
+		for id, a := range h.Candidates {
+			if answers[id] == nil {
+				answers[id] = map[string]delivery.CandidateAnswer{}
+			}
+			answers[id][node] = a
+		}
+	}
+	sort.Strings(ids)
+	out := []openProposal{}
+	for _, id := range ids {
+		if want := arg(args, "id"); want != "" && want != id {
+			continue
+		}
+		p, err := s.proposal(id)
+		if err != nil {
+			return nil, err
+		}
+		o := openProposal{Proposal: p, Candidates: map[string]uint64{}, Answers: answers[id]}
+		for _, k := range cands {
+			pid, node, err := delivery.ParsePlacementCandidateKey(k)
+			if err != nil || pid != id {
+				continue
+			}
+			if _, rev, found, err := s.st.get(delivery.PlacementCandidatesState, k); err == nil && found {
+				o.Candidates[node] = rev
+			}
+		}
+		out = append(out, o)
+	}
+	if arg(args, "id") != "" && len(out) == 0 {
+		return nil, fmt.Errorf("no proposal %s is open", arg(args, "id"))
+	}
+	return map[string]any{"proposals": out}, nil
+}
+
+// tools are the seat's verbs as the runtime serves them, each named <seat>.<verb> (the tool runner serves a seat's verb
+// only from a tool of that name), with the seat's own schemas.
+func (s *seatTools) tools() []stdio.Tool {
+	seat, _ := catalogue.SeatNamed(catalogue.PlacementSeat)
+	input := map[string]map[string]any{}
+	description := map[string]string{}
+	for _, v := range seat.Serves {
+		input[v.Name], description[v.Name] = v.Input, v.Description
+	}
+	run := map[string]func(map[string]any) (any, error){
+		catalogue.PlacementVerbPlacement: s.doPlacement,
+		catalogue.PlacementVerbProposals: s.doProposals,
+		catalogue.PlacementVerbPropose:   func(a map[string]any) (any, error) { return s.doPropose(a, stdio.CallerOf(a)) },
+		catalogue.PlacementVerbWithdraw:  func(a map[string]any) (any, error) { return s.doWithdraw(a, stdio.CallerOf(a)) },
+		catalogue.PlacementVerbAgain:     s.doAgain,
+		catalogue.PlacementVerbAdopt:     func(a map[string]any) (any, error) { return s.doAdopt(a, stdio.CallerOf(a)) },
+		catalogue.PlacementVerbHandBack:  func(a map[string]any) (any, error) { return s.doHandBack(a, stdio.CallerOf(a)) },
+	}
+	var out []stdio.Tool
+	for _, v := range seat.Serves {
+		out = append(out, stdio.Tool{Name: catalogue.PlacementSeat + "." + v.Name, Description: description[v.Name], Input: input[v.Name], Run: run[v.Name]})
+	}
+	return out
+}

modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/seat_tools_test.go

@@ -0,0 +1,167 @@
+package main
+
+import (
+	"encoding/json"
+	"os"
+	"slices"
+	"strings"
+	"testing"
+	"time"
+
+	stdio "git.novox.be/novox/mesh-sdk/go"
+	"git.novox.be/novox/mesh-sdk/go/buscompose"
+	"git.novox.be/novox/mesh-sdk/go/catalogue"
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+)
+
+func (s memStore) del(state, key string) error {
+	delete(s[state].values, key)
+	return nil
+}
+
+func (s memStore) history(state, key string) ([]stdio.StateRevision, error) {
+	v, ok := s[state].values[key]
+	if !ok {
+		return nil, nil
+	}
+	return []stdio.StateRevision{{Key: key, Value: v, Revision: uint64(len(v)), Op: "put"}}, nil
+}
+
+// ADR 0567 §2, §7, §10: the seat's seven verbs over the states. propose lays a proposal and writes it with its candidates,
+// or refuses naming every finding and writes nothing; withdraw and again mark it for the holder; adopt proposes the
+// controller's export whole as the seed, once; hand-back records the hand act and deletes every key; placement and
+// proposals read every state the seat keeps, and history names the stream for what the state no longer keeps.
+func TestTheSeatsVerbs(t *testing.T) {
+	anchor := delivery.Placement{V: delivery.Version, Node: "anchor", Modules: []delivery.PlacedModule{{Module: "web"}}}
+	st := memStore{}
+	for _, state := range []string{delivery.PlacementState, delivery.PlacementProposalsState, delivery.PlacementCandidatesState, modulesState, haveState} {
+		st[state] = &memKV{values: map[string][]byte{}}
+	}
+	for _, m := range []string{"web", "shell"} {
+		st[modulesState].values[m] = []byte("{}")
+	}
+	for _, n := range []string{"anchor", "laptop"} {
+		raw, _ := delivery.EncodeHaveNode(delivery.HaveNode{Record: &delivery.NodeRecord{Node: n}})
+		st[haveState].values[n+".node"] = raw
+	}
+	export, _ := json.Marshal(map[string]any{"anchor": anchor})
+	var asked []string
+	s := newSeatTools(st, func(key string, body any) (json.RawMessage, error) {
+		asked = append(asked, key)
+		if key == exportCall {
+			out, _ := json.Marshal(map[string]any{"ok": true, "output": string(export)})
+			return out, nil
+		}
+		return json.RawMessage(`{"ok":true}`), nil
+	})
+	s.now = func() time.Time { return time.Date(2026, 10, 28, 20, 0, 0, 0, time.UTC) }
+
+	// adopt: the export proposed whole as the seed, once.
+	got, err := s.doAdopt(map[string]any{"why": "take over"}, "operator@laptop")
+	if err != nil {
+		t.Fatal(err)
+	}
+	seed := got.(proposed).Proposal
+	if !seed.Seed || seed.ExportDigest != delivery.ExportDigest(map[string]delivery.Placement{"anchor": anchor}) || !slices.Equal(asked, []string{exportCall}) ||
+		len(st[delivery.PlacementCandidatesState].values) != 1 || st[delivery.PlacementProposalsState].values[seed.ID] == nil {
+		t.Fatalf("adopt = %+v, asked %v", seed, asked)
+	}
+	if _, err := s.doAdopt(map[string]any{"why": "again"}, "op"); err == nil || !strings.Contains(err.Error(), "is open") {
+		t.Errorf("a second adopt with a seed open: %v", err)
+	}
+	// withdraw and again mark the proposal; the holder ends or judges it.
+	if _, err := s.doWithdraw(map[string]any{"id": seed.ID, "why": "not yet"}, "op"); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := s.doAgain(map[string]any{"id": seed.ID}); err != nil {
+		t.Fatal(err)
+	}
+	if p, err := s.proposal(seed.ID); err != nil || !strings.Contains(p.Withdrawn, "not yet") || p.Again.IsZero() {
+		t.Errorf("marked = %+v, %v", p, err)
+	}
+	if _, err := s.doWithdraw(map[string]any{"id": "p-none", "why": "x"}, "op"); err == nil {
+		t.Error("an unknown proposal was withdrawn")
+	}
+	delete(st[delivery.PlacementProposalsState].values, seed.ID) // the holder ended it
+	st[delivery.PlacementCandidatesState].values = map[string][]byte{}
+
+	// propose: refused whole, naming every finding; a valid move laid over the keys at their revisions.
+	raw, _ := delivery.EncodePlacement(anchor)
+	st[delivery.PlacementState].values["placement.anchor"] = raw
+	if _, err := s.doPropose(map[string]any{"why": "x", "changes": `[{"op":"place","node":"anchor","module":"ghost"},{"op":"hold","node":"anchor","module":"web","claim":"x"}]`}, "op"); err == nil ||
+		!strings.Contains(err.Error(), "ghost") || !strings.Contains(err.Error(), "lease write") || len(st[delivery.PlacementProposalsState].values) != 0 {
+		t.Errorf("a refused proposal: %v", err)
+	}
+	if _, err := s.doPropose(map[string]any{"why": "x", "changes": `[{"op":"swap","node":"anchor"}]`}, "op"); err == nil {
+		t.Error("an unknown change was taken")
+	}
+	got, err = s.doPropose(map[string]any{"why": "move web", "changes": []any{
+		map[string]any{"op": "take-off", "node": "anchor", "module": "web"}, map[string]any{"op": "place", "node": "laptop", "module": "web"}}}, "operator@laptop")
+	if err != nil {
+		t.Fatal(err)
+	}
+	move := got.(proposed).Proposal
+	if move.By != "operator@laptop" || move.Base["anchor"] != uint64(len(raw)) || move.Base["laptop"] != 0 || len(st[delivery.PlacementCandidatesState].values) != 2 {
+		t.Fatalf("propose = %+v", move)
+	}
+
+	// placement and proposals read every state the seat keeps (§10); history names the stream for what is older.
+	reads := map[string]bool{}
+	pa, err := s.doPlacement(map[string]any{"module": "web", "history": "true"})
+	if a := pa.(placementAnswer); err != nil || !slices.Equal(a.Nodes, []string{"anchor"}) || len(a.Changes) != 1 || !strings.Contains(a.Older, delivery.PlacementStream) {
+		t.Errorf("placement of web = %+v, %v", pa, err)
+	} else {
+		reads[delivery.PlacementState], reads["stream "+delivery.PlacementStream] = true, true
+	}
+	if _, err := s.doPlacement(map[string]any{"node": "laptop"}); err == nil {
+		t.Error("a node with no key was answered")
+	}
+	ps, err := s.doProposals(map[string]any{"id": move.ID})
+	if list := ps.(map[string]any)["proposals"].([]openProposal); err != nil || len(list) != 1 || len(list[0].Candidates) != 2 {
+		t.Errorf("proposals = %+v, %v", ps, err)
+	} else {
+		reads[delivery.PlacementProposalsState], reads[delivery.PlacementCandidatesState] = true, true
+	}
+	raw0, err := readManifest()
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, state := range raw0.State {
+		if slices.Contains([]string{delivery.PlacementState, delivery.PlacementProposalsState, delivery.PlacementCandidatesState}, state.Name) && !reads[state.Name] {
+			t.Errorf("no verb reads the seat's state %s", state.Name)
+		}
+	}
+	for _, stream := range raw0.Streams {
+		if !reads["stream "+stream.Name] {
+			t.Errorf("no verb reads the seat's stream %s", stream.Name)
+		}
+	}
+
+	// hand-back: the operator's alone, written as a hand-back proposal naming every key at its revision, for the assigner
+	// to ask; nothing is deleted by the verb.
+	got, err = s.doHandBack(map[string]any{"why": "back"}, "op")
+	if hb := got.(proposed).Proposal; err != nil || !hb.HandBack || hb.Base["anchor"] != uint64(len(raw)) || len(st[delivery.PlacementState].values) != 1 {
+		t.Errorf("hand-back = %+v, %v", got, err)
+	}
+	// Issue 774 (ADR 0567 §8): once the controller's lease is handed away a change its verbs cannot take is proposed, and
+	// there is no controller to hand placement back to.
+	st[buscompose.ControllerLease] = &memKV{values: map[string][]byte{buscompose.ControllerLeaseKey: []byte(`{"handed-to":"the operator's hand-over","handed-by":"person.jochen"}`)}}
+	if _, err := s.doPropose(map[string]any{"why": "hold", "changes": `[{"op":"hold","node":"anchor","module":"web","claim":"node-shell","scope":"node"}]`}, "op"); err != nil {
+		t.Errorf("a hold after the lease write: %v", err)
+	}
+	if _, err := s.doHandBack(map[string]any{"why": "back"}, "op"); err == nil || !strings.Contains(err.Error(), "since the lease write") {
+		t.Errorf("a hand-back after the lease write: %v", err)
+	}
+	if tools := s.tools(); len(tools) != 7 || tools[2].Name != "mesh-placement.propose" || tools[2].Run == nil || tools[2].Input == nil {
+		t.Errorf("the seat's verbs as served: %+v", tools)
+	}
+}
+
+// readManifest is the module's manifest, read as the controller reads it.
+func readManifest() (catalogue.Manifest, error) {
+	raw, err := os.ReadFile("../../module.json")
+	if err != nil {
+		return catalogue.Manifest{}, err
+	}
+	return catalogue.ParseManifest(raw)
+}

modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/tools.go

@@ -18,8 +18,8 @@ import (
 
 // The assigner's tools (novox/hq ADR 0546), served through the tool runner from its bundle: a process never serves (ADR
 // 0436, mesh-sdk process). They write and read the puts; the assigner's process takes each put further (puts.go) and says
-// every step as the event put. They are the module's own tools, not a seat's verbs: a new seat needs a change of the
-// controller, which takes none; they become the verbs of a seat once composing leaves the controller.
+// every step as the event put. They are the module's own tools; the seat mesh-placement's verbs are served beside them
+// (seat_tools.go, ADR 0567 §10).
 
 // putsState is the assigner's state of puts, as the runtime names a module's own state.
 const putsState = "puts"
@@ -351,7 +351,7 @@ func serveTools() error {
 			time.Sleep(wait)
 		}
 	}()
-	return stdio.Serve("", s.tools())
+	return stdio.Serve("", append(s.tools(), newSeatTools(runtimeStore{}, stdio.Ask).tools()...))
 }
 
 // shortFP is a fingerprint's first twelve hex digits.

modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/world.go

@@ -13,7 +13,10 @@ import (
 
 	"github.com/nats-io/nats.go/jetstream"
 
+	"git.novox.be/novox/mesh-sdk/go/buscompose"
 	"git.novox.be/novox/mesh-sdk/go/catalogue"
+	"git.novox.be/novox/mesh-sdk/go/compose"
+	"git.novox.be/novox/mesh-sdk/go/compose/frombus"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 	"git.novox.be/novox/mesh-sdk/go/provider"
 
@@ -46,6 +49,14 @@ type world struct {
 	healthy map[string][]string
 	// changes counts, by bucket and key, the values this process has seen the key take: a value written again is another.
 	changes map[string]uint64
+	// meta is, by bucket and key, the revision and the time of the value held now, where the watch said them (putEntry).
+	meta map[string]entryMeta
+}
+
+// entryMeta is a value's revision in its bucket and when it was written.
+type entryMeta struct {
+	revision uint64
+	at       time.Time
 }
 
 // parsed is a manifest read by digest: its module and its manifest, or why it cannot be read.
@@ -56,7 +67,27 @@ type parsed struct {
 }
 
 func newWorld() *world {
-	return &world{values: map[string]map[string][]byte{}, manifests: map[string]parsed{}, healthy: map[string][]string{}, changes: map[string]uint64{}}
+	return &world{values: map[string]map[string][]byte{}, manifests: map[string]parsed{}, healthy: map[string][]string{}, changes: map[string]uint64{},
+		meta: map[string]entryMeta{}}
+}
+
+// putEntry is put, keeping the value's revision and the time it was written.
+func (w *world) putEntry(bucket, key string, value []byte, revision uint64, at time.Time) {
+	w.put(bucket, key, value)
+	w.mu.Lock()
+	defer w.mu.Unlock()
+	if value == nil {
+		delete(w.meta, bucket+"|"+key)
+		return
+	}
+	w.meta[bucket+"|"+key] = entryMeta{revision: revision, at: at}
+}
+
+// metaOf is the revision and time of the value a bucket holds at key, as the watch said them.
+func (w *world) metaOf(bucket, key string) entryMeta {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+	return w.meta[bucket+"|"+key]
 }
 
 // put takes a change of a watched bucket in: a value, or nil for a key deleted or purged.
@@ -162,8 +193,73 @@ func (w *world) manifest(ctx context.Context, get getter, digest string) parsed
 	return p
 }
 
-// assigned is each node's modules with an open assignment, read from the controller's assignments, in name order.
+// assigned is each node's modules both the controller's assignments and the seat mesh-placement's placement name, in name order
+// (ADR 0549 §5; the assignments alone before any placement was read), with every open assignment by node and module.
+// Once the controller's lease is handed away it is the seat's placement alone, with no assignment (ADR 0549 §5, §6).
 func (w *world) assigned() (map[string][]string, map[string]assignment) {
+	// A lease handed away before any placement was read keeps the assignments as they last stood, never an empty mesh:
+	// the lease write's own check refuses that order (ADR 0547 §11).
+	placed, seeded := w.placed()
+	byAssignment, all := w.assignedByController()
+	if away := w.handedAway(); away && seeded {
+		both, _ := assign.Placed(byAssignment, placed, seeded, away)
+		return both, map[string]assignment{}
+	}
+	both, _ := assign.Placed(byAssignment, placed, seeded, false)
+	return both, all
+}
+
+// placementDiffers is every pair the controller's assignments and the seat's placement do not both name: none once
+// the controller's lease is handed away, since the placement is then the one source.
+func (w *world) placementDiffers() []assign.Pair {
+	placed, seeded := w.placed()
+	byAssignment, _ := w.assignedByController()
+	_, differ := assign.Placed(byAssignment, placed, seeded, w.handedAway())
+	return differ
+}
+
+// handedAway says the controller's lease is handed to a holder that is no controller (mesh-sdk buscompose.LeaseHandedAway,
+// ADR 0561 §3): from then the seat mesh-placement's placement alone names where modules run (ADR 0549 §5). A lease not read (its
+// bucket not granted or not there), a controller's, expired or unreadable, is not handed away.
+func (w *world) handedAway() bool {
+	raw, found := w.read(buscompose.LeaseBucket)[buscompose.ControllerLeaseKey]
+	away, _ := buscompose.LeaseHandedAway(raw, found && raw != nil, nil)
+	return away
+}
+
+// placed is each node's modules in the seat's placement (ADR 0567 §1), and whether any placement key was read: a key
+// that does not read places nothing on its node and is said by the indexer's own read tool.
+func (w *world) placed() (map[string][]string, bool) {
+	out := map[string][]string{}
+	values := w.read(delivery.PlacementBucket)
+	for key, value := range values {
+		node, err := delivery.ParsePlacementKey(key)
+		if err != nil {
+			continue
+		}
+		p, err := delivery.DecodePlacement(value)
+		if err != nil || p.Node != node {
+			continue
+		}
+		out[node] = p.Assigned()
+	}
+	return out, len(values) > 0
+}
+
+// placedNodes is every node the seat's placement names (ADR 0567 §1): those compose their own modules (ADR 0547 §2),
+// so their wants name the build alone and the seventh rule does not hold them.
+func (w *world) placedNodes() map[string]bool {
+	placed, _ := w.placed()
+	out := make(map[string]bool, len(placed))
+	for node := range placed {
+		out[node] = true
+	}
+	return out
+}
+
+// assignedByController is each node's modules with an open assignment, read from the controller's assignments, in
+// name order.
+func (w *world) assignedByController() (map[string][]string, map[string]assignment) {
 	out, all := map[string][]string{}, map[string]assignment{}
 	for _, value := range w.read(provider.AssignmentsBucket) {
 		var a assignment
@@ -210,9 +306,128 @@ func (w *world) mesh(ctx context.Context, manifests getter) assign.Mesh {
 		}
 		m.Manifests[name] = p.manifest
 	}
+	// Once the catalogue places the nodes, the check composes over the input they compose from (ADR 0547 §2, ADR 0549
+	// §3): one composer's input for the check and the nodes. An input that cannot be read is said, and the nodes and their
+	// assignments alone are composed, as before any placement.
+	if _, seeded := w.placed(); seeded {
+		in, err := frombus.Input(ctx, worldReader{w: w, manifests: manifests}, frombus.Mesh{}, frombus.Scope{Every: true})
+		if err != nil {
+			m.InputUnread = err.Error()
+		} else {
+			m.Input = &in
+		}
+	}
 	return m
 }
 
+// worldReader is what the assigner watched as frombus reads the bus: the seat's placement, the indexer's modules, each node's
+// record in its own have key, the manifests by digest; the check reads no config value, own secret or credential (the
+// composition it asks resolves, and stands in for what it does not carry).
+type worldReader struct {
+	w         *world
+	manifests getter
+}
+
+func (r worldReader) Placements(context.Context) (map[string]delivery.Placement, error) {
+	out := map[string]delivery.Placement{}
+	for key, value := range r.w.read(delivery.PlacementBucket) {
+		node, err := delivery.ParsePlacementKey(key)
+		if err != nil {
+			continue
+		}
+		if p, err := delivery.DecodePlacement(value); err == nil && p.Node == node {
+			out[node] = p
+		}
+	}
+	return out, nil
+}
+
+func (r worldReader) Records(context.Context) (map[string]delivery.NodeRecord, error) {
+	out := map[string]delivery.NodeRecord{}
+	for key, value := range r.w.read(delivery.HaveBucket) {
+		node, _, isNode, err := delivery.ParseHaveKey(key)
+		if err != nil || !isNode {
+			continue
+		}
+		if h, err := delivery.DecodeHaveNode(value); err == nil && h.Record != nil {
+			out[node] = *h.Record
+		}
+	}
+	return out, nil
+}
+
+func (r worldReader) Modules(context.Context) (map[string]delivery.Module, error) {
+	return r.w.trunk(), nil
+}
+
+func (r worldReader) Manifest(ctx context.Context, digest string) ([]byte, error) {
+	key, err := delivery.ManifestsKey(digest)
+	if err != nil {
+		return nil, err
+	}
+	raw, err := r.manifests(ctx, key)
+	if err != nil {
+		return nil, err
+	}
+	m, err := delivery.DecodeManifest(raw)
+	if err != nil {
+		return nil, err
+	}
+	return []byte(m.JSON), nil
+}
+
+// Values is one module's config values on one node as mesh-config resolved them, each a value its source lays
+// (catalogue.LaidValue): the holder composes every node a proposal touches with them (ADR 0567 §9).
+func (r worldReader) Values(_ context.Context, node, module string) (map[string]any, error) {
+	var out map[string]any
+	prefix := node + "." + module + "."
+	for key, raw := range r.w.read(buscompose.ResolvedBucket) {
+		name, ok := strings.CutPrefix(key, prefix)
+		if !ok || strings.Contains(name, ".") {
+			continue
+		}
+		if v, laid := catalogue.LaidValue(raw); laid {
+			if out == nil {
+				out = map[string]any{}
+			}
+			out[name] = v
+		}
+	}
+	return out, nil
+}
+
+func (worldReader) OwnSecrets(context.Context, string) ([]compose.OwnSecretRow, error) {
+	return nil, nil
+}
+
+func (worldReader) Credentials(context.Context, string, []compose.CredentialKey, []compose.CredentialKey) ([]compose.Credential, []compose.Issued, error) {
+	return nil, nil, nil
+}
+
+// Build and Archive are read only for a node composing itself (frombus.Scope without Every): the check of every node
+// composes from the manifests the indexer read, and reads no build and no archive.
+func (worldReader) Build(context.Context, string, string) (*delivery.BuilderBuild, error) {
+	return nil, nil
+}
+
+func (worldReader) Archive(_ context.Context, url, _ string) ([]byte, error) {
+	return nil, fmt.Errorf("the composition check reads no archive (%s)", url)
+}
+
+func (r worldReader) Served(ctx context.Context, node, module string, keys []string) (map[string]any, error) {
+	all, err := r.Values(ctx, node, module)
+	var out map[string]any
+	for _, k := range keys {
+		if v, ok := all[k]; ok {
+			if out == nil {
+				out = map[string]any{}
+			}
+			out[k] = v
+		}
+	}
+	return out, err
+}
+
 // change is a candidate's change for the composition check, or why the composition waits for it.
 func (w *world) change(ctx context.Context, manifests getter, c delivery.Candidate, trunk map[string]delivery.Module) (assign.Change, string) {
 	ch := assign.Change{Group: c.Group, Heads: c.HeadsHash, Manifests: map[string]catalogue.Manifest{}, Unreadable: map[string]string{},
@@ -265,6 +480,21 @@ func (w *world) change(ctx context.Context, manifests getter, c delivery.Candida
 	return ch, ""
 }
 
+// online is, by node, whether the watchman holds the node online.
+func (w *world) online() map[string]bool {
+	out := map[string]bool{}
+	for key, value := range w.read(delivery.PresenceBucket) {
+		node, _, _, err := delivery.ParsePresenceKey(key)
+		if err != nil || node == "" {
+			continue
+		}
+		if p, err := delivery.DecodePresence(value); err == nil {
+			out[node] = p.Online
+		}
+	}
+	return out
+}
+
 // wantsOf is the wants the assigner wrote, by module then node.
 func (w *world) wantsOf() map[string]map[string]delivery.Want {
 	out := map[string]map[string]delivery.Want{}
@@ -333,6 +563,16 @@ func (w *world) value(bucket, key string) []byte {
 	return w.values[bucket][key]
 }
 
+// grantsBucket is the bucket the grants are read from now (delivery.GrantSource): the grants part's while the controller's
+// lease is handed away, as the lease bucket's key says it (buscompose.LeaseHandedAway), the controller's in every other
+// case, a lease not held here included.
+func (w *world) grantsBucket() string {
+	raw := w.value(buscompose.LeaseBucket, buscompose.ControllerLeaseKey)
+	away, _ := buscompose.LeaseHandedAway(raw, raw != nil, nil)
+	bucket, _ := delivery.GrantSource(away)
+	return bucket
+}
+
 // has says whether a bucket holds a key now.
 func (w *world) has(bucket, key string) bool {
 	w.mu.Lock()

modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/world_test.go

@@ -6,7 +6,9 @@ import (
 	"slices"
 	"strings"
 	"testing"
+	"time"
 
+	"git.novox.be/novox/mesh-sdk/go/buscompose"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 
 	"mesh-delivery-assigner/internal/assign"
@@ -48,6 +50,7 @@ func pull(repo string, number int, modules map[string]delivery.CandidateModule)
 // module with no manifest in the preview as removed, a mesh-sdk member's head, and a module the trunk holds from
 // another repository as defined twice.
 func TestTheChangeOfACandidate(t *testing.T) {
+	theWorldCountsTheValuesAKeyTakes(t)
 	f := fakeManifests{}
 	web := f.add(t, "web", `{"module":"web","version":"2"}`)
 	mail := f.add(t, "mail", `{"module":"mail","version":"1"}`)
@@ -113,7 +116,7 @@ func TestAManifestFallingBackToAPredefinedKeyIsReadable(t *testing.T) {
 }
 
 // Review round 1 (items 3 and 4): the world counts the values a key takes, so a have written again after an answer is seen.
-func TestTheWorldCountsTheValuesAKeyTakes(t *testing.T) {
+func theWorldCountsTheValuesAKeyTakes(t *testing.T) {
 	w := newWorld()
 	w.put(delivery.HaveBucket, "ace.web", []byte(`{"v":1}`))
 	w.put(delivery.HaveBucket, "ace.web", []byte(`{"v":1}`))
@@ -124,4 +127,40 @@ func TestTheWorldCountsTheValuesAKeyTakes(t *testing.T) {
 	if got := w.changed(delivery.HaveBucket, "gone"); got != 0 {
 		t.Errorf("changed = %d for a key never seen", got)
 	}
+	// Issue 774: grants are read from the grants part's bucket only while the controller's lease is handed away: a grant
+	// only the part holds lets a node's put through then, and with a controller's lease (or none, or an unreadable one) it
+	// holds it, a grant only the controller holds being the one that counts instead.
+	fp := delivery.SourcePrefix2 + strings.Repeat("d", 64)
+	gkey, _ := delivery.ControllerGrantKey("web", fp)
+	grant, _ := delivery.EncodeControllerGrant(delivery.ControllerGrant{Accounts: []string{"ace.web"}})
+	for _, row := range []struct {
+		name, lease          string
+		inPart, inController bool
+		bucket               string
+		granted              bool
+	}{
+		{"handed away, the part's grant", `{"handed-to":"the operator's hand-over"}`, true, false, delivery.PartGrantsBucket, true},
+		{"handed away, only the controller's grant", `{"handed-to":"x"}`, false, true, delivery.PartGrantsBucket, false},
+		{"a controller holds it, only the part's grant", `{"instance":"novox/1","epoch":3}`, true, false, delivery.ControllerGrantsBucket, false},
+		{"a controller holds it, its own grant", `{"instance":"novox/1"}`, false, true, delivery.ControllerGrantsBucket, true},
+		{"no lease read", ``, true, false, delivery.ControllerGrantsBucket, false},
+		{"an unreadable lease", `[1]`, true, false, delivery.ControllerGrantsBucket, false},
+	} {
+		p := newPasser(buckets{}, time.Now())
+		if row.lease != "" {
+			p.w.put(buscompose.LeaseBucket, buscompose.ControllerLeaseKey, []byte(row.lease))
+		}
+		if row.inPart {
+			p.w.put(delivery.PartGrantsBucket, gkey, grant)
+		}
+		if row.inController {
+			p.w.put(delivery.ControllerGrantsBucket, gkey, grant)
+		}
+		if got := p.w.grantsBucket(); got != row.bucket {
+			t.Errorf("%s: grants are read from %s, want %s", row.name, got, row.bucket)
+		}
+		if _, granted := p.composedFor("ace", "web", fp); granted != row.granted {
+			t.Errorf("%s: granted = %v, want %v", row.name, granted, row.granted)
+		}
+	}
 }

modules/mesh-delivery-assigner/go.mod

@@ -3,7 +3,7 @@ module mesh-delivery-assigner
 go 1.26.0
 
 require (
-	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261025211220-e0d1de047585
+	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261028225633-76f7c4d2238f
 	github.com/nats-io/nats-server/v2 v2.11.17
 	github.com/nats-io/nats.go v1.54.0
 )

modules/mesh-delivery-assigner/go.sum

@@ -1,13 +1,5 @@
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261024210118-748c564cdf7c h1:pY2YpHSSsfDPBrOEiWTNSIPn0zdnAayRmtmmyQ3hCHY=
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261024210118-748c564cdf7c/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261025195051-20a6dc4920f8 h1:jA7V7hlfJAigVUvJDpKwfgd9ylQ9bqppg3rK9XgLWoA=
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261025195051-20a6dc4920f8/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261025200810-d4ae4b6790b8 h1:vhYk/iv43u2WGSTrFyQGDvGBxLaRITgMAiiI9DjuA10=
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261025200810-d4ae4b6790b8/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261025203528-db26f7e8b6f5 h1:gE80bR0tPME7MTMBLcdP62v+F/9soVXmdcBYNMOye44=
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261025203528-db26f7e8b6f5/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261025211220-e0d1de047585 h1:7QoFH5qjXRpx5M4uPdYsVJ5qKl2082gq8n0lFxhoNIg=
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261025211220-e0d1de047585/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261028225633-76f7c4d2238f h1:jCd8WN+Olo4nlaB1cz1HYpEV4xc6Mzw7viXdwU+0fic=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261028225633-76f7c4d2238f/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op h1:Z/MZK75wC/NSrkgqeNIa7jexam9uWzhLmFTSCPI/kn0=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op/go.mod h1:FQyySiasQQM8735Ddel3MRojmy4dA1IqCeyJ5jmPMbI=
 github.com/google/go-tpm v0.9.8 h1:slArAR9Ft+1ybZu0lBwpSmpwhRXaa85hWtMinMyRAWo=

modules/mesh-delivery-assigner/internal/assign/asks.go

@@ -81,6 +81,29 @@ func HeldCondition(module, fp, node, words string, raised, needsYou bool) asks.C
 	return c
 }
 
+// NodeFailedCondition is the condition the assigner raises for a module whose newest fingerprint fp failed its health check on
+// node while other nodes run it healthy (ADR 0557 §1, issue 1496): the failure is the node's, so nothing is held or set back and
+// the node keeps its want. It names the node, the module, fp and the have's words, keyed by node and module, and is cleared
+// (raised false) once the node no longer fails alone.
+func NodeFailedCondition(node, module, fp string, f NodeFailure, raised bool) asks.Condition {
+	key := delivery.AssignerModule + ".failed-alone." + node + "." + module
+	subject := asks.Scope{Scope: "module", ID: module, Machine: node}
+	if !raised {
+		return asks.Condition{Key: key, Subject: subject, State: asks.StateCleared,
+			Resolved: fmt.Sprintf("%s on %s no longer fails its health check alone.", module, node)}
+	}
+	headline := fmt.Sprintf("%s fails on %s alone", module, node)
+	if n := len([]rune(headline)); n > asks.HeadlineLength {
+		headline = string([]rune(headline)[:asks.HeadlineLength])
+	}
+	return asks.Condition{Key: key, Severity: asks.SeverityWarning, Subject: subject, State: asks.StateRaised,
+		Summary: headline, Headline: headline,
+		Explanation: fmt.Sprintf("%s The health check of %s at %s failed on %s (%s), while it runs healthy on %s. The failure is %s's, "+
+			"so the assigner holds nothing and sets no node back, and %s keeps its want. This clears once %s runs it healthy or "+
+			"another version is the newest.", asks.NothingToDo, module, short(fp), node, f.Words, strings.Join(f.Others, ", "), node,
+			node, node)}
+}
+
 // NeitherCondition is the condition of a module assigned to node that holds no want for it (issue 1945): the node's own composition
 // gives up every module with a fingerprint of the new form, so nothing applies it there and its files are gone. It is raised (urgent)
 // naming the module, the node and the rule holding its first want back with the rule's words, under the assigner's own name keyed by
@@ -96,6 +119,14 @@ func NeitherCondition(node, module string, h Holding, raised bool) asks.Conditio
 	if n := len([]rune(headline)); n > asks.HeadlineLength {
 		headline = string([]rune(headline)[:asks.HeadlineLength])
 	}
+	if h.Bus {
+		needs := fmt.Sprintf("put %s on %s with assigner_put", module, node)
+		return asks.Condition{Key: key, Severity: asks.SeverityUrgent, Subject: subject, State: asks.StateRaised,
+			Summary: headline, Headline: headline, Needs: needs,
+			Explanation: fmt.Sprintf("%s%s. %s is assigned to %s, but the node holds no want for it and the node's own composition does not "+
+				"hold it either, so nothing applies it there. The assigner never moves the bus: %s. This clears once the node has a want for it.",
+				asks.NeedsYou, needs, module, node, h.Words)}
+	}
 	return asks.Condition{Key: key, Severity: asks.SeverityUrgent, Subject: subject, State: asks.StateRaised,
 		Summary: headline, Headline: headline,
 		Explanation: fmt.Sprintf("%s %s is assigned to %s, but the node holds no want for it and the node's own composition does not "+
@@ -103,6 +134,17 @@ func NeitherCondition(node, module string, h Holding, raised bool) asks.Conditio
 			"rule holds, and clears this.", asks.NothingToDo, module, node, h.Rule, h.Words)}
 }
 
+// NeitherLeftCondition clears the neither condition of module on node when it is no longer on neither list: why is "" when the
+// node has a live want for it again, else why it has none (it is held, its move waits for an ask, the node no longer runs it), so
+// the clear never says a want the node does not hold (issue 1945: "nats on novox has a want again" while it had none).
+func NeitherLeftCondition(node, module, why string) asks.Condition {
+	c := NeitherCondition(node, module, Holding{}, false)
+	if why != "" {
+		c.Resolved = fmt.Sprintf("%s on %s is no longer on neither list and has no want: %s.", module, node, why)
+	}
+	return c
+}
+
 // LiftedCondition clears the condition of a held fingerprint the assigner lifted by itself, saying why (issue 1906).
 func LiftedCondition(module, fp string) asks.Condition {
 	c := HeldCondition(module, fp, "", "", false, false)

modules/mesh-delivery-assigner/internal/assign/compose.go

@@ -35,6 +35,13 @@ type Mesh struct {
 	// Digests is every trunk module's manifest digest in the indexer's manifests bucket, readable or not: what a
 	// composer at another mesh-sdk reads (issue 1622).
 	Digests map[string]string
+	// Input is the rest of the mesh as the nodes compose from it, filled by mesh-sdk's frombus from the catalogue's
+	// placement and the nodes' records (novox/hq ADR 0547 §2, ADR 0549 §3, issue 1126), so the check and the nodes share
+	// one composer's input; nil before any placement is read, when the nodes and their assignments alone are composed.
+	Input *compose.Input
+	// InputUnread says why that input could not be read from the bus, when it could not: the check then composes the
+	// nodes and their assignments alone, and says so in its warnings.
+	InputUnread string
 }
 
 // Change is a group's change as the indexer's candidate holds it: the manifest of every module it moves or adds, those
@@ -57,7 +64,8 @@ type Change struct {
 // Touched is the machines a change touches (ADR 0446 clause 3): those running a module the change moves, adds or
 // removes, those running a consumer of a provision such a module provides (before or after), and those running a
 // provider of a provision such a module requires after the change. A module the change adds that is assigned nowhere
-// touches no machine.
+// touches no machine. A change of placement is no change of a repository (ADR 0567 §4): the seat
+// mesh-placement judges it.
 func Touched(m Mesh, c Change) []string {
 	moved := map[string]bool{}
 	for name := range c.Manifests {
@@ -272,6 +280,18 @@ func GrantsAlone(m Mesh, c Change, composed []string) []string {
 	return out
 }
 
+// withOverlay is base with every manifest of over laid over it, a copy.
+func withOverlay(base, over map[string]catalogue.Manifest) map[string]catalogue.Manifest {
+	out := make(map[string]catalogue.Manifest, len(base)+len(over))
+	for name, man := range base {
+		out[name] = man
+	}
+	for name, man := range over {
+		out[name] = man
+	}
+	return out
+}
+
 func sortedKeys[V any](m map[string]V) []string {
 	out := make([]string, 0, len(m))
 	for k := range m {

modules/mesh-delivery-assigner/internal/assign/composer.go

@@ -42,9 +42,17 @@ func HeadJob(m Mesh, c Change) (delivery.ComposeJob, error) {
 	for _, name := range c.Removed {
 		delete(change, name)
 	}
-	req := composer.Request{V: composer.Version, Input: plainInput(m.Assigned), Depth: composer.DepthResolve,
-		HoldingsFromClaims: true, Machines: Touched(m, c),
-		Cases: []composer.Case{{Name: CaseTrunk, Manifests: trunk}, {Name: CaseChange, Manifests: change}}}
+	in, fromClaims := plainInput(m.Assigned), true
+	if m.Input != nil {
+		// The input the nodes compose from, without its catalogue: the cases carry the manifests (issue 1126).
+		in = *m.Input
+		in.Catalogue = nil
+		fromClaims = len(in.Holdings) == 0
+	}
+	changeCase := composer.Case{Name: CaseChange, Manifests: change}
+	req := composer.Request{V: composer.Version, Input: in, Depth: composer.DepthResolve,
+		HoldingsFromClaims: fromClaims, Machines: Touched(m, c),
+		Cases: []composer.Case{{Name: CaseTrunk, Manifests: trunk}, changeCase}}
 	return job(SDKRepository, c.SDKHead, SDKDir, req, "the mesh-sdk head of "+c.Group)
 }
 
@@ -195,6 +203,10 @@ func FromComposer(m Mesh, c Change, head Ran, readers []Reader, took time.Durati
 	readerFails, readerWarnings := judgeReaders(c, change, readers)
 	fails = append(fails, readerFails...)
 	v.Warnings = append(v.Warnings, readerWarnings...)
+	if m.InputUnread != "" {
+		v.Warnings = append(v.Warnings, "composed over the nodes and their assignments alone: the input the nodes compose from "+
+			"cannot be read from the bus ("+m.InputUnread+")")
+	}
 	return finish(v, m, c, machines, fails)
 }
 

modules/mesh-delivery-assigner/internal/assign/composer_test.go

@@ -8,6 +8,7 @@ import (
 	"time"
 
 	"git.novox.be/novox/mesh-sdk/go/catalogue"
+	"git.novox.be/novox/mesh-sdk/go/compose"
 	"git.novox.be/novox/mesh-sdk/go/composer"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 )
@@ -100,6 +101,25 @@ func TestAGroupWithAnSDKMemberAsksTheComposerAtItsHead(t *testing.T) {
 	if !slices.Equal(req.Machines, []string{"g14"}) || req.Depth != composer.DepthResolve || !req.HoldingsFromClaims {
 		t.Errorf("request = machines %v, depth %q, holdings from claims %v", req.Machines, req.Depth, req.HoldingsFromClaims)
 	}
+
+	// 1126 (ADR 0547 §2, ADR 0549 §3): once the catalogue places the nodes, the check composes over the input the nodes
+	// compose from (frombus), its catalogue left to the cases, and the seats held as placement says.
+	m := digestedMesh()
+	m.Input = &compose.Input{Catalogue: map[string]catalogue.Manifest{"web": {Module: "web"}},
+		Nodes:    []compose.Node{{Name: "g14", Assigned: []string{"web"}, Place: compose.Place{Endpoint: "g14.example:51820"}}},
+		Holdings: []catalogue.Held{{Claim: "web-seat", Scope: "mesh", Node: "g14", Module: "web"}}}
+	placedJob, err := HeadJob(m, c)
+	if err != nil {
+		t.Fatal(err)
+	}
+	placed, err := composer.Decode(placedJob.Request)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if placed.Input.Catalogue != nil || len(placed.Input.Nodes) != 1 || placed.Input.Nodes[0].Place.Endpoint != "g14.example:51820" ||
+		len(placed.Input.Holdings) != 1 || placed.HoldingsFromClaims {
+		t.Errorf("the placed check's request = %+v, holdings from claims %v", placed.Input, placed.HoldingsFromClaims)
+	}
 }
 
 // 1622/AC2, AC3: a catalogue member using a field only the SDK head reads passes with the head's composer, and the

modules/mesh-delivery-assigner/internal/assign/placement.go

@@ -0,0 +1,132 @@
+package assign
+
+import (
+	"fmt"
+	"slices"
+	"sort"
+	"strings"
+
+	"git.novox.be/novox/mesh-sdk/go/asks"
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+)
+
+// Until ADR 0547's third milestone two sources name which module runs on which node: the controller's assignments and
+// the seat mesh-placement's placement (ADR 0549 §5, ADR 0567 §8). The assigner writes wants only for a pair both name:
+// for a pair one source names alone it writes no want and touches none it wrote before, so nothing moves and nothing is
+// removed on one source's word, and it raises a condition naming the pair until both agree. After an approved proposal
+// the assigner keeps the controller in step itself, calling its assign, unassign, pin and unpin; a call refused or not
+// yet answered leaves the pair differing, and the condition names the call (Pair.Call). Before the first placement key
+// is written the controller's assignments are the one source, as before. From the lease write (the controller's lease
+// handed away) the placement is the one source.
+
+// Pair is a module on a node that one source names and the other does not; Only says which: OnlyAssignments or
+// OnlyPlacement.
+type Pair struct {
+	Node, Module, Only string
+	// Call is what became of the assigner's call of the controller's verb for the pair, in words, when it made one.
+	Call string
+}
+
+// The source that names a pair alone.
+const (
+	OnlyAssignments = "the controller's assignments"
+	OnlyPlacement   = "the seat mesh-placement's placement"
+)
+
+// Placed is, by node, the modules both sources name, in name order, and every pair one names alone, by node then
+// module. With no placement read yet (seeded false) it is the assignments, and no pair differs. Once the controller's
+// lease is handed away (handedAway, ADR 0549 §5, §6) it is the placement alone, in name order, and no pair differs: the
+// assignments are then a source of nothing.
+func Placed(assigned, placed map[string][]string, seeded, handedAway bool) (map[string][]string, []Pair) {
+	if handedAway && seeded {
+		out := make(map[string][]string, len(placed))
+		for node, modules := range placed {
+			out[node] = slices.Sorted(slices.Values(modules))
+		}
+		return out, nil
+	}
+	if !seeded {
+		return assigned, nil
+	}
+	set := func(m map[string][]string) map[string]bool {
+		out := map[string]bool{}
+		for node, modules := range m {
+			for _, module := range modules {
+				out[node+"\x00"+module] = true
+			}
+		}
+		return out
+	}
+	inAssigned, inPlaced := set(assigned), set(placed)
+	both := map[string][]string{}
+	var differ []Pair
+	for node, modules := range assigned {
+		for _, module := range modules {
+			if inPlaced[node+"\x00"+module] {
+				both[node] = append(both[node], module)
+			} else {
+				differ = append(differ, Pair{Node: node, Module: module, Only: OnlyAssignments})
+			}
+		}
+	}
+	for node, modules := range placed {
+		for _, module := range modules {
+			if !inAssigned[node+"\x00"+module] {
+				differ = append(differ, Pair{Node: node, Module: module, Only: OnlyPlacement})
+			}
+		}
+	}
+	for _, modules := range both {
+		sort.Strings(modules)
+	}
+	sort.Slice(differ, func(i, j int) bool {
+		if differ[i].Node != differ[j].Node {
+			return differ[i].Node < differ[j].Node
+		}
+		return differ[i].Module < differ[j].Module
+	})
+	return both, differ
+}
+
+// PlacementCondition is the condition of a pair the two sources do not both name: raised while they differ, cleared once
+// both name it or neither does.
+func PlacementCondition(p Pair, raised bool) asks.Condition {
+	key := delivery.AssignerModule + ".placement." + p.Node + "." + p.Module
+	subject := asks.Scope{Scope: "module", ID: p.Module, Machine: p.Node}
+	if !raised {
+		return asks.Condition{Key: key, Subject: subject, State: asks.StateCleared,
+			Resolved: fmt.Sprintf("the controller's assignments and the seat's placement agree on %s on %s.", p.Module, p.Node)}
+	}
+	headline := fmt.Sprintf("%s on %s is placed by one source only", p.Module, p.Node)
+	if n := len([]rune(headline)); n > asks.HeadlineLength {
+		headline = string([]rune(headline)[:asks.HeadlineLength])
+	}
+	var needs string
+	if p.Only == OnlyAssignments {
+		needs = fmt.Sprintf("propose placing %s on %s (mesh-placement.propose), or unassign it at the controller", p.Module, p.Node)
+	} else {
+		needs = fmt.Sprintf("assign %s to %s at the controller, as the approved placement says, or propose taking it off", p.Module, p.Node)
+	}
+	if p.Call != "" {
+		needs += "; the assigner's call: " + p.Call
+	}
+	return asks.Condition{Key: key, Severity: asks.SeverityUrgent, Subject: subject, State: asks.StateRaised,
+		Summary: headline, Headline: headline, Needs: needs,
+		Explanation: fmt.Sprintf("%s%s. %s names %s on %s and the other source does not. Until ADR 0547's third milestone both must "+
+			"name a module on a node (ADR 0549 §5): the assigner writes no want for it there and leaves the one it wrote before, so "+
+			"nothing moves or is removed. This clears once both name it or neither does.", asks.NeedsYou, needs, p.Only, p.Module, p.Node)}
+}
+
+// SeatWaitsCondition is the assigner's word on the seat mesh-placement while a state of the seat is not bound (ADR 0567
+// §1): raised naming each, cleared when none is left.
+func SeatWaitsCondition(unbound []string) asks.Condition {
+	key := delivery.AssignerModule + ".seat-states"
+	subject := asks.Scope{Scope: "module", ID: delivery.AssignerModule}
+	if len(unbound) == 0 {
+		return asks.Condition{Key: key, Subject: subject, State: asks.StateCleared, Resolved: "the seat mesh-placement holds all its states."}
+	}
+	why := "the seat waits for its states: " + strings.Join(unbound, ", ") + " are not on the bus or not granted yet"
+	return asks.Condition{Key: key, Severity: asks.SeverityWarning, Subject: subject, State: asks.StateRaised,
+		Summary: "the seat waits for its states", Headline: "the seat waits for its states",
+		Explanation: asks.NothingToDo + " " + why + "; each is bound at the next pass once it is, with no restart."}
+}

modules/mesh-delivery-assigner/internal/assign/seat.go

@@ -0,0 +1,296 @@
+package assign
+
+import (
+	"encoding/json"
+	"fmt"
+	"sort"
+	"strings"
+	"time"
+
+	"git.novox.be/novox/mesh-sdk/go/asks"
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+)
+
+// The seat mesh-placement (novox/hq ADR 0567), held by the assigner beside its wants: placement is its state
+// `placement`, changed only by a proposal (§2) the nodes it touches answer (§3), judged (§4) and written on the
+// operator's Approve at the revision it was laid over (§5). What here decides; the tools and the passes do.
+
+// ProposeIn is what a proposal is laid over: its id, who and why, its changes; every node's current placement and the
+// revision of its key; which modules the indexer holds and which nodes have a record; and, for the seed, the export's
+// digest.
+type ProposeIn struct {
+	ID, By, Why  string
+	At           time.Time
+	Changes      []delivery.PlacementProposalChange
+	Current      map[string]delivery.Placement
+	Revisions    map[string]uint64
+	Held         func(module string) bool
+	Recorded     func(node string) bool
+	Seed         bool
+	ExportDigest string
+	// Leased says the lease write of ADR 0547 has happened (the controller's lease handed away, mesh-sdk
+	// buscompose.LeaseHandedAway; issue 774), after which the controller's assignments are read no more (§8): until then
+	// the holder keeps the controller in step and refuses what its verbs cannot take.
+	Leased bool
+}
+
+// Propose lays a proposal over the current keys (§2): the proposal (state answering, each changed node's base revision),
+// the laid placement of every node whose key it changes, and every finding, which refuses it whole: a change the
+// controller's verbs cannot take before the lease write (§8), a change that does not fit its node, and what
+// CheckPlacements refuses of the result laid over every placement (two modules on one host port, a provider not placed,
+// a seat held once held twice, two nodes with one address, two hubs, a module the indexer does not hold, a node with no
+// record). A key whose value the proposal leaves as it is changes nothing and is not laid.
+func Propose(in ProposeIn) (delivery.PlacementProposal, map[string]*delivery.Placement, []string) {
+	p := delivery.PlacementProposal{ID: in.ID, By: strings.TrimSpace(in.By), Why: strings.TrimSpace(in.Why), At: in.At.UTC(),
+		Changes: in.Changes, Seed: in.Seed, ExportDigest: in.ExportDigest, Base: map[string]uint64{}, State: delivery.ProposalAnswering}
+	var findings []string
+	if p.By == "" {
+		findings = append(findings, "the runtime names no caller: a proposal is made by someone")
+	}
+	if p.Why == "" {
+		findings = append(findings, "a proposal says why: it is shown to the operator")
+	}
+	if len(in.Changes) == 0 {
+		findings = append(findings, "a proposal changes something: it names no change")
+	}
+	for i, c := range in.Changes {
+		if (c.Op == delivery.OpSeed) != in.Seed {
+			findings = append(findings, fmt.Sprintf("change %d: the seed is adopt's alone, and never mixed with other changes", i+1))
+			continue
+		}
+		if !in.Leased {
+			if why := c.BeforeLease(); why != "" {
+				findings = append(findings, fmt.Sprintf("change %d: %s", i+1, why))
+			}
+		}
+	}
+	laid, lay := delivery.LayChanges(in.Current, in.Changes)
+	findings = append(findings, lay...)
+	all := map[string]delivery.Placement{}
+	for node, pl := range in.Current {
+		all[node] = pl
+	}
+	out := map[string]*delivery.Placement{}
+	for node, pl := range laid {
+		if before, ok := in.Current[node]; ok && delivery.SamePlacement(before, pl) {
+			continue
+		}
+		pl := pl
+		all[node] = pl
+		out[node] = &pl
+		p.Base[node] = in.Revisions[node]
+	}
+	if len(findings) == 0 && len(out) == 0 {
+		findings = append(findings, "the changes leave every placement as it is")
+	}
+	held, recorded := in.Held, in.Recorded
+	if held == nil {
+		held = func(string) bool { return false }
+	}
+	if recorded == nil {
+		recorded = func(string) bool { return false }
+	}
+	for _, r := range delivery.CheckPlacements(all, held, recorded) {
+		findings = append(findings, r)
+	}
+	return p, out, findings
+}
+
+// Write is one key a warrant writes (§5): the node, its key, the revision it is written at (0: it has none, so it is
+// created) and its value (nil: it is deleted).
+type Write struct {
+	Node, Key string
+	Base      uint64
+	Value     *delivery.Placement
+}
+
+// Writes is every key a proposal writes, by node order.
+func Writes(p delivery.PlacementProposal, laid map[string]*delivery.Placement) ([]Write, error) {
+	var out []Write
+	for _, node := range p.Nodes() {
+		key, err := delivery.PlacementKey(node)
+		if err != nil {
+			return nil, err
+		}
+		out = append(out, Write{Node: node, Key: key, Base: p.Base[node], Value: laid[node]})
+	}
+	return out, nil
+}
+
+// ControllerCall is one call of the controller's seat verbs the holder makes after writing an approved proposal, until
+// the lease write (§8): assign, unassign, pin or unpin, with its arguments.
+type ControllerCall struct {
+	Verb string
+	Args map[string]any
+	// Node and Module name the pair the call keeps in step (a pin names no module).
+	Node, Module string
+}
+
+// Key names the call, as the condition of its pair says it.
+func (c ControllerCall) Key() string {
+	return fmt.Sprintf("mesh-controller.%s %s %s", c.Verb, c.Node, c.Module)
+}
+
+// ControllerCalls is every call that brings the controller's assignments and pins to the placement after: assign for a
+// module placed on a node before not, unassign for one taken off, pin for a pin set or changed, unpin for one removed,
+// each naming the proposal and its warrant in its why. In node order, unassigns before assigns, so a module moved
+// between nodes is first taken off.
+func ControllerCalls(before map[string]delivery.Placement, after map[string]*delivery.Placement, proposal, warrant string) []ControllerCall {
+	why := fmt.Sprintf("placement proposal %s, approved (%s)", proposal, warrant)
+	nodes := make([]string, 0, len(after))
+	for node := range after {
+		nodes = append(nodes, node)
+	}
+	sort.Strings(nodes)
+	var off, on, pins []ControllerCall
+	for _, node := range nodes {
+		was, now := before[node], delivery.Placement{}
+		if a := after[node]; a != nil {
+			now = *a
+		}
+		had, has := map[string]bool{}, map[string]bool{}
+		for _, m := range was.Modules {
+			had[m.Module] = true
+		}
+		for _, m := range now.Modules {
+			has[m.Module] = true
+			if !had[m.Module] {
+				on = append(on, ControllerCall{Verb: "assign", Node: node, Module: m.Module, Args: map[string]any{"node": node, "module": m.Module}})
+			}
+		}
+		for _, m := range was.Modules {
+			if !has[m.Module] {
+				off = append(off, ControllerCall{Verb: "unassign", Node: node, Module: m.Module, Args: map[string]any{"node": node, "module": m.Module}})
+			}
+		}
+		for _, provision := range sortedKeys(now.Pins) {
+			to := now.Pins[provision]
+			if old, ok := was.Pins[provision]; !ok || old != to {
+				pins = append(pins, ControllerCall{Verb: "pin", Node: node, Module: provision,
+					Args: map[string]any{"node": node, "provision": provision, "from": to.Node, "module": to.Module}})
+			}
+		}
+		for _, provision := range sortedKeys(was.Pins) {
+			if _, ok := now.Pins[provision]; !ok {
+				pins = append(pins, ControllerCall{Verb: "unpin", Node: node, Module: provision, Args: map[string]any{"node": node, "provision": provision}})
+			}
+		}
+	}
+	out := append(append(off, on...), pins...)
+	for i := range out {
+		out[i].Args["why"] = why
+	}
+	return out
+}
+
+// PlacementAct is the act an approved proposal's yes binds: writing exactly its changes at its base revisions.
+func PlacementAct(p delivery.PlacementProposal) asks.Act {
+	return asks.Act{"placement": "write", "proposal": p.ID, "changes": delivery.ChangesDigest(p)}
+}
+
+// PlacementAsking is a proposal's asking number: each judging that raises its ask again (again, a key moved) is
+// another asking, under an id of its own.
+func PlacementAsking(p delivery.PlacementProposal, at time.Time) int {
+	return int(at.Unix())
+}
+
+// PlacementAsk is the authorising ask about a proposal (§5): an Approve that binds its act, so only a channel that
+// proves who answered takes it, with the brief of the verdict by node (judge.Brief) as its explanation.
+func PlacementAsk(key string, p delivery.PlacementProposal, brief string, asking int, now time.Time) (delivery.AssignerAsk, error) {
+	binds, err := asks.ActDigest(PlacementAct(p))
+	if err != nil {
+		return delivery.AssignerAsk{}, err
+	}
+	nodes := p.Nodes()
+	headline := fmt.Sprintf("Change placement on %s?", strings.Join(nodes, ", "))
+	if p.Seed {
+		headline = "Take placement over from the controller?"
+	}
+	if n := len([]rune(headline)); n > asks.HeadlineLength {
+		headline = fmt.Sprintf("Change placement on %d machines?", len(nodes))
+	}
+	return delivery.AssignerAsk{Ask: asks.Ask{
+		ID:          delivery.AskingID(key, asking),
+		Headline:    headline,
+		Explanation: brief,
+		Options: []asks.Option{
+			{ID: OptionYes, Label: "Approve", Does: "the placement of " + strings.Join(nodes, ", ") + " is written as proposed",
+				Level: asks.Approve, Binds: binds},
+			{ID: OptionNo, Label: "Decline", Does: "nothing is written, and the proposal ends", Level: asks.Acknowledge},
+		},
+		Who:      asks.Operator,
+		Expires:  now.Add(asks.ApproveLasts),
+		OnExpiry: "nothing is written, and the proposal ends",
+		About:    key,
+	}, Asking: asking}, nil
+}
+
+// ExportOf reads the controller's answer to placement-export (§7): its verb answers what the command printed, the
+// JSON of every node's placement, in `output` (the controller's verbAnswer; `answer` when it carries it as data). A
+// refused or unreadable answer is an error naming it.
+func ExportOf(raw []byte) (map[string]delivery.Placement, error) {
+	var a struct {
+		Output string          `json:"output"`
+		OK     *bool           `json:"ok"`
+		Answer json.RawMessage `json:"answer"`
+	}
+	if err := json.Unmarshal(raw, &a); err != nil {
+		return nil, fmt.Errorf("the controller's placement-export answered no verb answer: %w", err)
+	}
+	if a.OK != nil && !*a.OK {
+		return nil, fmt.Errorf("the controller's placement-export refused: %s", strings.TrimSpace(a.Output))
+	}
+	var byNode map[string]json.RawMessage
+	if len(a.Answer) > 0 && string(a.Answer) != "null" {
+		if err := json.Unmarshal(a.Answer, &byNode); err != nil {
+			return nil, fmt.Errorf("the controller's placement-export is no placement by node: %w", err)
+		}
+	} else if err := json.NewDecoder(strings.NewReader(a.Output)).Decode(&byNode); err != nil {
+		// The command prints its JSON first; what its standard error said after it is left.
+		return nil, fmt.Errorf("the controller's placement-export printed no placement by node: %w", err)
+	}
+	out := map[string]delivery.Placement{}
+	for node, rawP := range byNode {
+		p, err := delivery.DecodePlacement(rawP)
+		if err != nil {
+			return nil, fmt.Errorf("the controller's placement-export of %s cannot be read: %w", node, err)
+		}
+		if p.Node != node {
+			return nil, fmt.Errorf("the controller's placement-export names %s under %s", p.Node, node)
+		}
+		out[node] = p
+	}
+	if len(out) == 0 {
+		return nil, fmt.Errorf("the controller's placement-export names no node")
+	}
+	return out, nil
+}
+
+// SeedChanges is the seed's changes: every node's placement of the export, whole, in node order.
+func SeedChanges(export map[string]delivery.Placement) []delivery.PlacementProposalChange {
+	var out []delivery.PlacementProposalChange
+	for _, node := range sortedKeys(export) {
+		p := export[node]
+		out = append(out, delivery.PlacementProposalChange{Op: delivery.OpSeed, Node: node, Whole: &p})
+	}
+	return out
+}
+
+// Rest is what a proposal leaves to write once the keys of written are: its changes of the other nodes, to be laid again
+// over the keys as the write left them (§5: a key moved while it was written). False when nothing is left.
+func Rest(p delivery.PlacementProposal, written map[string]*delivery.Placement) (delivery.PlacementProposal, bool) {
+	rest := p
+	rest.Changes, rest.Base = nil, map[string]uint64{}
+	for _, c := range p.Changes {
+		if _, done := written[c.Node]; !done {
+			rest.Changes = append(rest.Changes, c)
+		}
+	}
+	for node, base := range p.Base {
+		if _, done := written[node]; !done {
+			rest.Base[node] = base
+		}
+	}
+	rest.Must, rest.Verdict, rest.Ask, rest.State = nil, nil, "", delivery.ProposalAnswering
+	return rest, len(rest.Changes) > 0
+}

modules/mesh-delivery-assigner/internal/assign/seat_test.go

@@ -0,0 +1,157 @@
+package assign
+
+import (
+	"encoding/json"
+	"slices"
+	"strings"
+	"testing"
+	"time"
+
+	"git.novox.be/novox/mesh-sdk/go/asks"
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+)
+
+// ADR 0567 §2, §5, §7, §8: what the seat's holder decides of a proposal: every refusal named at once, a valid one laid
+// with the base revision of each key it changes, the writes at those revisions, the controller's calls that keep its
+// assignments in step, the authorising ask bound to the changes, and the export read as the controller answers it.
+func TestThePlacementSeatDecides(t *testing.T) {
+	anchor := delivery.Placement{V: delivery.Version, Node: "anchor", Decided: delivery.NodeDecided{Hub: true, Address: "10.0.0.1"},
+		Modules: []delivery.PlacedModule{{Module: "store", Ports: map[string]int{"5432": 5432}}, {Module: "web"}}}
+	laptop := delivery.Placement{V: delivery.Version, Node: "laptop", Decided: delivery.NodeDecided{Address: "10.0.0.2"}, Modules: []delivery.PlacedModule{{Module: "shell"}}}
+	in := func(changes ...delivery.PlacementProposalChange) ProposeIn {
+		return ProposeIn{ID: "p-one", By: "operator@laptop", Why: "move web", At: time.Unix(1, 0), Changes: changes,
+			Current: map[string]delivery.Placement{"anchor": anchor, "laptop": laptop}, Revisions: map[string]uint64{"anchor": 4, "laptop": 9},
+			Held:     func(m string) bool { return m != "ghost" },
+			Recorded: func(n string) bool { return n == "anchor" || n == "laptop" }}
+	}
+	move := []delivery.PlacementProposalChange{{Op: delivery.OpTakeOff, Node: "anchor", Module: "web"}, {Op: delivery.OpPlace, Node: "laptop", Module: "web"}}
+	p, laid, findings := Propose(in(move...))
+	if len(findings) != 0 || p.State != delivery.ProposalAnswering || p.Base["anchor"] != 4 || p.Base["laptop"] != 9 ||
+		!slices.Equal(laid["laptop"].Assigned(), []string{"shell", "web"}) || !slices.Equal(laid["anchor"].Assigned(), []string{"store"}) {
+		t.Fatalf("a move: %+v, %+v, %v", p, laid, findings)
+	}
+	if _, err := delivery.EncodePlacementProposal(p); err != nil {
+		t.Fatalf("the proposal cannot be written: %v", err)
+	}
+	for name, c := range map[string]struct {
+		in   ProposeIn
+		want string
+	}{
+		"a port before the lease": {in(delivery.PlacementProposalChange{Op: delivery.OpPlace, Node: "laptop", Module: "web", Ports: map[string]int{"80": 8080}}), "lease write"},
+		"a holding":               {in(delivery.PlacementProposalChange{Op: delivery.OpHold, Node: "anchor", Module: "store", Claim: "mesh-store", Scope: "mesh"}), "lease write"},
+		"a binding":               {in(delivery.PlacementProposalChange{Op: delivery.OpPlace, Node: "laptop", Module: "web", Bindings: map[string]delivery.Provider{"db": {Node: "anchor", Module: "store"}}}), "lease write"},
+		"a config place":          {in(delivery.PlacementProposalChange{Op: delivery.OpConfig, Node: "anchor", Module: "web", Layer: map[string]any{"places": []any{}}}), "lease write"},
+		"a config access":         {in(delivery.PlacementProposalChange{Op: delivery.OpConfig, Node: "anchor", Module: "web", MeshWide: map[string]any{"accesses": []any{}}}), "lease write"},
+		"a module not held":       {in(delivery.PlacementProposalChange{Op: delivery.OpPlace, Node: "laptop", Module: "ghost"}), "the indexer holds no module ghost"},
+		"a node with no record":   {in(delivery.PlacementProposalChange{Op: delivery.OpPlace, Node: "stranger", Module: "web"}), "stranger is a node with no record"},
+		"nothing changes":         {in(delivery.PlacementProposalChange{Op: delivery.OpPlace, Node: "anchor", Module: "web"}), "leave every placement as it is"},
+		"no why":                  {func() ProposeIn { i := in(move...); i.Why = " "; return i }(), "says why"},
+		"no caller":               {func() ProposeIn { i := in(move...); i.By = ""; return i }(), "names no caller"},
+		"a seed by hand":          {in(delivery.PlacementProposalChange{Op: delivery.OpSeed, Node: "laptop", Whole: &laptop}), "adopt's alone"},
+		"a pin of nobody placed":  {in(delivery.PlacementProposalChange{Op: delivery.OpPin, Node: "laptop", Provision: "db", Provider: &delivery.Provider{Node: "laptop", Module: "store"}}), "not placed there"},
+	} {
+		if _, _, f := Propose(c.in); !slices.ContainsFunc(f, func(s string) bool { return strings.Contains(s, c.want) }) {
+			t.Errorf("%s: findings %v, want one naming %q", name, f, c.want)
+		}
+	}
+
+	// A module's config values may be proposed before the lease write (§13); once the lease is written every change is
+	// the state's alone, and none waits.
+	if _, _, f := Propose(in(delivery.PlacementProposalChange{Op: delivery.OpConfig, Node: "anchor", Module: "web", Values: map[string]any{"puid": 1}})); len(f) != 0 {
+		t.Errorf("config values before the lease write: %v", f)
+	}
+	for _, c := range []delivery.PlacementProposalChange{
+		{Op: delivery.OpPlace, Node: "laptop", Module: "web", Ports: map[string]int{"80": 8080}, Bindings: map[string]delivery.Provider{"db": {Node: "anchor", Module: "store"}}},
+		{Op: delivery.OpConfig, Node: "anchor", Module: "web", Layer: map[string]any{"places": []any{}}},
+		{Op: delivery.OpDecide, Node: "laptop", Field: "site", Value: json.RawMessage(`"attic"`)},
+		{Op: delivery.OpHold, Node: "anchor", Module: "store", Claim: "node-shell", Scope: "node"},
+	} {
+		leased := in(c)
+		leased.Leased = true
+		if _, _, f := Propose(leased); len(f) != 0 {
+			t.Errorf("after the lease write %s is refused: %v", c.Op, f)
+		}
+	}
+
+	// A key moved while the warrant wrote: what is left to write is the other nodes' changes, to be laid and asked again.
+	if rest, ok := Rest(p, map[string]*delivery.Placement{"anchor": laid["anchor"]}); !ok || len(rest.Changes) != 1 || rest.Changes[0].Node != "laptop" ||
+		len(rest.Base) != 1 || rest.State != delivery.ProposalAnswering || rest.Must != nil {
+		t.Errorf("the rest = %+v, %v", rest, ok)
+	}
+	if _, ok := Rest(p, laid); ok {
+		t.Error("a proposal written whole leaves something to write")
+	}
+
+	// The seat says it waits while one of its states is not bound, naming it, and clears once all are.
+	for _, unbound := range [][]string{{delivery.PlacementPulsesBucket}, nil} {
+		c := SeatWaitsCondition(unbound)
+		if _, err := asks.EncodeCondition(c); err != nil || (len(unbound) > 0) != (c.State == asks.StateRaised) ||
+			(len(unbound) > 0 && !strings.Contains(c.Explanation, "the seat waits for its states: "+delivery.PlacementPulsesBucket)) {
+			t.Errorf("waiting for %v: %+v, %v", unbound, c, err)
+		}
+	}
+
+	// Issue 1126: the seed places the private network, which no repository holds; it is the mesh's own, and passes.
+	wired := laptop
+	wired.Modules = append(slices.Clone(laptop.Modules), delivery.PlacedModule{Module: "mesh-wireguard"})
+	seed := in(SeedChanges(map[string]delivery.Placement{"laptop": wired})...)
+	seed.Seed, seed.ExportDigest, seed.Current, seed.Revisions = true, "sha256:x", map[string]delivery.Placement{}, map[string]uint64{}
+	seed.Held = func(m string) bool { return m != "mesh-wireguard" } // the indexer holds every module but it
+	if _, _, f := Propose(seed); len(f) != 0 {
+		t.Errorf("a seed placing the private network is refused: %v", f)
+	}
+
+	writes, err := Writes(p, laid)
+	if err != nil || len(writes) != 2 || writes[0].Key != "placement.anchor" || writes[0].Base != 4 || writes[1].Base != 9 {
+		t.Fatalf("writes = %+v, %v", writes, err)
+	}
+	pinned := *laid["laptop"]
+	pinned.Pins = map[string]delivery.Provider{"db": {Node: "anchor", Module: "store"}}
+	calls := ControllerCalls(map[string]delivery.Placement{"anchor": anchor, "laptop": laptop},
+		map[string]*delivery.Placement{"anchor": laid["anchor"], "laptop": &pinned}, "p-one", "w1@t")
+	var said []string
+	for _, c := range calls {
+		said = append(said, c.Key())
+		if !strings.Contains(c.Args["why"].(string), "p-one") {
+			t.Errorf("%s does not name the proposal: %v", c.Key(), c.Args)
+		}
+	}
+	if !slices.Equal(said, []string{"mesh-controller.unassign anchor web", "mesh-controller.assign laptop web", "mesh-controller.pin laptop db"}) {
+		t.Errorf("the controller's calls = %v", said)
+	}
+
+	a, err := PlacementAsk("placement.p-one", p, "move web (proposed by operator@laptop)", 7, time.Unix(100, 0))
+	if err != nil || a.Ask.Check(time.Unix(100, 0)) != nil || a.Ask.Options[0].Level != asks.Approve || a.Ask.Options[0].Performs(PlacementAct(p)) != nil {
+		t.Fatalf("the ask = %+v, %v", a, err)
+	}
+	q := p
+	q.Changes = append(slices.Clone(p.Changes), delivery.PlacementProposalChange{Op: delivery.OpUnpin, Node: "laptop", Provision: "x"})
+	if a.Ask.Options[0].Performs(PlacementAct(q)) == nil {
+		t.Error("the ask's yes binds changes it was not asked about")
+	}
+
+	export, _ := json.Marshal(map[string]any{"anchor": anchor, "laptop": laptop})
+	for name, c := range map[string]struct {
+		raw  string
+		want int
+	}{
+		"in output":  {`{"ok":true,"output":` + quote(string(export)+"\n") + `}`, 2},
+		"as answer":  {`{"ok":true,"output":"","answer":` + string(export) + `}`, 2},
+		"refused":    {`{"ok":false,"output":"no store"}`, 0},
+		"no node":    {`{"ok":true,"output":"{}"}`, 0},
+		"no version": {`{"ok":true,"output":"{\"anchor\":{\"node\":\"anchor\",\"modules\":[]}}"}`, 0},
+	} {
+		got, err := ExportOf([]byte(c.raw))
+		if len(got) != c.want || (c.want == 0) != (err != nil) {
+			t.Errorf("%s: %d nodes, %v", name, len(got), err)
+		}
+	}
+	if seed := SeedChanges(map[string]delivery.Placement{"laptop": laptop, "anchor": anchor}); len(seed) != 2 || seed[0].Node != "anchor" || seed[0].Op != delivery.OpSeed {
+		t.Errorf("the seed's changes = %+v", seed)
+	}
+}
+
+func quote(s string) string {
+	raw, _ := json.Marshal(s)
+	return string(raw)
+}

modules/mesh-delivery-assigner/internal/assign/wants.go

@@ -2,6 +2,7 @@ package assign
 
 import (
 	"fmt"
+	"maps"
 	"slices"
 	"sort"
 	"strings"
@@ -46,8 +47,14 @@ type Module struct {
 	Now time.Time
 	// Puts are the puts of the module, by node (ADR 0546): while one owns a node's want (PutOwns), the rules pass over it.
 	Puts map[string]delivery.Put
+	// Self says whether node composes the module itself: the catalogue's placement names the node (ADR 0547 §2). It is the one
+	// source of a want's Self: every want the rules write or keep is derived from it (selfDerived), so a want written Self while
+	// the node was placed does not outlive the placement (issue 1126). Nil: no node does.
+	Self func(node string) bool
 }
 
+func (m Module) selfOn(node string) bool { return m.Self != nil && m.Self(node) }
+
 func (m Module) composition(node, fp string) (delivery.ComposedDigest, bool) {
 	if m.Composed == nil {
 		return delivery.ComposedDigest{}, false
@@ -169,6 +176,9 @@ type Outcome struct {
 	// Lifted is the hold of m.FP lifted by itself: every node that runs the module runs m.FP healthy (issue 1906). The held
 	// record and its ask are taken away, and the wants move by the rules again in this pass.
 	Lifted bool
+	// NodeFailed is, by node, a failed health check of m.FP on a node while another node runs m.FP healthy: the failure is
+	// that node's, so m.FP is not held and nothing is set back (ADR 0557 §1, issue 1496). The pass raises its condition once.
+	NodeFailed map[string]NodeFailure
 	// Record is the moves a person must allow before the want names them: each is asked once (ADR 0539 §14).
 	Record []RecordNeed
 	// Restore is the nodes of a module holding data whose held fingerprint failed its health check there and that are not set
@@ -192,10 +202,27 @@ type RecordNeed struct {
 	Words     string
 }
 
-// Holding is a rule holding a node back, and why.
+// Holding is a rule holding a node back, and why. Bus marks the bar on the bus instead of one of the seven rules (Rule is then
+// 0): the bus moves only by the operator's put (ADR 0539 §15, ADR 0546 §8), never by the assigner (issue 1945: nats on novox,
+// running an old-form build, got no want and the pass said nothing).
 type Holding struct {
 	Rule  int
 	Words string
+	Bus   bool
+}
+
+// Reason is the holding in words: the rule and its words, or for the bus bar its words alone.
+func (h Holding) Reason() string {
+	if h.Bus {
+		return h.Words
+	}
+	return fmt.Sprintf("rule %d: %s", h.Rule, h.Words)
+}
+
+// BusBarWords say why the assigner writes no want moving the bus on node: it runs prev, the trunk builds fp, and only the
+// operator's put moves it (ADR 0539 §15, ADR 0546 §8). The words reach the operator, so they name no record.
+func BusBarWords(node, prev, fp string) string {
+	return fmt.Sprintf("only your put moves the bus: %s runs %s, the trunk builds %s; put it with assigner_put", node, short(prev), short(fp))
 }
 
 // Wants is the pass of one module m: for each of its nodes, the want by the six rules, starting from the want written
@@ -211,11 +238,25 @@ func Wants(m Module, n Nodes, wants map[string]delivery.Want, lastHealthy map[st
 	}
 	if !held && !out.Lifted && !m.Released && m.FP != "" {
 		for _, node := range slices.Sorted(slices.Values(m.Nodes)) {
-			if h, ok := n.Haves[node][m.Name]; ok && h.FP == m.FP && failed(h) {
-				out.Held = &delivery.Held{Node: node, Words: HeldWords(h, m.Now)}
-				held = true
-				break
+			h, ok := n.Haves[node][m.Name]
+			if !ok || h.FP != m.FP || !failed(h) {
+				continue
 			}
+			if others := healthyElsewhere(m, n, node); len(others) > 0 && !failedElsewhere(m, n, node) {
+				// F runs healthy on another node, so its failure here is this node's, not F's: F is not held, no node is set back,
+				// and the failing node keeps its want (ADR 0557 §1; issue 1496: on ace a newly assigned mesh-build-node failed its
+				// first check and the hold moved shanks, g14 and novox, healthy on F for an hour, back). The pass raises the node's
+				// condition. With no online healthy witness, or with F failed on a second node, the hold and the set-back stand (ADR 0557
+				// §2, ADR 0429 §6).
+				if out.NodeFailed == nil {
+					out.NodeFailed = map[string]NodeFailure{}
+				}
+				out.NodeFailed[node] = NodeFailure{Others: others, Words: HeldWords(h, time.Time{})} // said once: no clock in it
+				continue
+			}
+			out.Held = &delivery.Held{Node: node, Words: HeldWords(h, m.Now)}
+			held = true
+			break
 		}
 	}
 	mm := m
@@ -281,6 +322,13 @@ func Wants(m Module, n Nodes, wants map[string]delivery.Want, lastHealthy map[st
 				ok, target = true, have.FP
 			}
 		}
+		if ok && target == m.FP && len(out.NodeFailed) > 0 && !(had && !before.Removed && before.FP == m.FP) &&
+			n.Haves[node][m.Name].FP != m.FP {
+			// While a node fails F alone, F reaches no further node: a node that neither wants nor runs F gets no new want
+			// naming it, and wants already written stay (ADR 0557 §2). A node that runs F with no live want gets its want at F, or
+			// it would be on neither list and its node-engine would give the module up (issue 1945).
+			ok, rule, words = false, delivery.RuleNotHeld, FailedAloneWords(m.Name, m.FP, slices.Sorted(maps.Keys(out.NodeFailed)))
+		}
 		switch {
 		case ok:
 			d, _ := m.composition(node, target)
@@ -303,6 +351,14 @@ func Wants(m Module, n Nodes, wants map[string]delivery.Want, lastHealthy map[st
 			if need, wait := at.mustAsk(node, asked, hadLive, ran, running.FP, running.Composed == "", d); wait {
 				if need != nil {
 					out.Record = append(out.Record, *need)
+				} else if prev, barred := at.busBar(asked, hadLive, running.FP); barred {
+					// The bus is barred: no want moves it but the operator's put. Said, never silent (issue 1945): its holding is named,
+					// and a node that runs it with no live want has it on neither list, so its condition stays raised.
+					h := Holding{Bus: true, Words: BusBarWords(node, prev, at.FP)}
+					out.Rules[node] = h
+					if !hadLive && running.Phase != delivery.PhaseRemoved && !held {
+						out.Neither[node] = h
+					}
 				}
 				continue
 			}
@@ -368,6 +424,10 @@ func Wants(m Module, n Nodes, wants map[string]delivery.Want, lastHealthy map[st
 				}
 			}
 		}
+		next, write := m.selfDerived(node, before, had, next, n, &out)
+		if !write {
+			continue
+		}
 		if !had || !delivery.SameWant(normal(before), normal(next)) {
 			out.Wants[node] = next
 		}
@@ -380,6 +440,43 @@ func Wants(m Module, n Nodes, wants map[string]delivery.Want, lastHealthy map[st
 	return out
 }
 
+// selfDerived is next with its Self derived from the placement now (Module.Self), whichever rule made it, and whether it is
+// written. A placed node's want names the build alone (ADR 0547 §2). An unplaced node's want that a rule kept from the want
+// written while the node was placed (held at F, held back by rule 3 or 5, a data module asked about) names the controller's
+// composition of the same fingerprint, asked as any move of a record module is (ADR 0539 §14): on 2026-10-27, after the
+// placement seed's revert, g14's systemd-resolved (held) and forticlient (rule 5), and shanks's forticlient (rule 3), kept
+// their Self wants, which their node agents, no longer placed, could not compose (issue 1126). With no such composition, or
+// while its ask waits, the want written stays and the node's holding says why.
+func (m Module) selfDerived(node string, before delivery.Want, had bool, next delivery.Want, n Nodes, out *Outcome) (delivery.Want, bool) {
+	switch {
+	case next.Removed:
+		return next, true
+	case m.selfOn(node):
+		next.Self, next.Composed = true, ""
+		return next, true
+	case !next.Self && next.Composed != "":
+		return next, true
+	}
+	next.Self, next.Yes = false, ""
+	d, there := m.composition(node, next.FP)
+	if !there || d.Digest == "" {
+		out.Rules[node] = Holding{Rule: delivery.RuleComposed, Words: fmt.Sprintf("%s on %s was composed by the node while it was placed, "+
+			"and the controller has not composed it at %s, so its want stays", m.Name, node, short(next.FP))}
+		return next, false
+	}
+	at := m
+	at.FP = next.FP
+	running, ran := n.Haves[node][m.Name]
+	if need, wait := at.mustAsk(node, before, had, ran, running.FP, running.Composed == "", d); wait {
+		if need != nil && !slices.Contains(out.Record, *need) { // the branch held back at an older fingerprint may have asked it
+			out.Record = append(out.Record, *need)
+		}
+		return next, false
+	}
+	next.Composed = d.Digest
+	return next, true
+}
+
 // NoWantWords say why a node gets no want for a module: the rule that holds its first want back and why (issue 1945).
 func NoWantWords(rule int, words string) string {
 	return fmt.Sprintf("no want: rule %d: %s", rule, words)
@@ -394,6 +491,43 @@ func failed(h delivery.Have) bool {
 	return h.Health == delivery.HealthFailed && (h.Phase == delivery.PhaseRunning || h.Phase == delivery.PhaseFailed)
 }
 
+// healthyElsewhere is every online node of m but node that runs m.FP healthy, by name.
+func healthyElsewhere(m Module, n Nodes, node string) []string {
+	var out []string
+	for _, other := range slices.Sorted(slices.Values(m.Nodes)) {
+		// A witness is online: a node that sleeps keeps the have it last wrote, and a stale have is no evidence that F runs
+		// healthy now.
+		if other != node && n.Online[other] && healthy(n.Haves[other][m.Name], m.FP) {
+			out = append(out, other)
+		}
+	}
+	return out
+}
+
+// failedElsewhere says whether another node of m has a have naming m.FP failed: then the failure is not one node's alone, and
+// the hold and the set-back stand at the second failure (ADR 0557 §2).
+func failedElsewhere(m Module, n Nodes, node string) bool {
+	for _, other := range m.Nodes {
+		if h, ok := n.Haves[other][m.Name]; ok && other != node && h.FP == m.FP && failed(h) {
+			return true
+		}
+	}
+	return false
+}
+
+// FailedAloneWords say why a node gets no new want naming fp: fp fails its health check on the nodes named, alone.
+func FailedAloneWords(module, fp string, failing []string) string {
+	return fmt.Sprintf("%s at %s fails its health check on %s, so no further node moves to it until that is over", module, short(fp),
+		strings.Join(failing, ", "))
+}
+
+// NodeFailure is a failed health check of a module's newest fingerprint on one node while it runs healthy on Others: the have's
+// health, phase and words (HeldWords without a time), and the healthy witnesses by name.
+type NodeFailure struct {
+	Others []string
+	Words  string
+}
+
 // runs says whether a have is of a module the node runs: running, whatever its health.
 func runs(h delivery.Have) bool {
 	return h.Phase == delivery.PhaseRunning
@@ -466,12 +600,7 @@ func (m Module) mustAsk(node string, before delivery.Want, had, ran bool, runnin
 	if !had && ran && running == m.FP && haveNamesNoComposition && d.Judgement == delivery.JudgedUnchanged {
 		return nil, false
 	}
-	// The fingerprint the bus ran before: its want's, or with no readable want the one its have names (ADR 0539 §15 bars a new one).
-	prev := before.FP
-	if !had {
-		prev = running
-	}
-	if catalogue.ProvidesBus(m.Manifest) && prev != m.FP {
+	if _, barred := m.busBar(before, had, running); barred {
 		return nil, true // the bus is never moved by the assigner; the operator writes its want (§15)
 	}
 	if !m.recorded(d) || d.Judgement == delivery.JudgedNeither || d.Judgement == delivery.JudgedUnchanged {
@@ -483,6 +612,16 @@ func (m Module) mustAsk(node string, before delivery.Want, had, ran bool, runnin
 	return &RecordNeed{Node: node, Digest: d.Digest, Judgement: d.Judgement, Words: d.Words}, true
 }
 
+// busBar says whether m is the bus and the move would take it off the fingerprint it ran before, prev: its want's, or with no
+// readable want the one its have names (ADR 0539 §15 bars a new one).
+func (m Module) busBar(before delivery.Want, had bool, running string) (prev string, barred bool) {
+	prev = before.FP
+	if !had {
+		prev = running
+	}
+	return prev, catalogue.ProvidesBus(m.Manifest) && prev != m.FP
+}
+
 // recorded says whether the module is of policy record: as the controller holds it beside the composition's digest, the
 // operator's own choice included (ADR 0539 §14); on a composition made by hand, which carries none, as the manifest derives it.
 func (m Module) recorded(d delivery.ComposedDigest) bool {

modules/mesh-delivery-assigner/internal/assign/wants_test.go

@@ -87,6 +87,96 @@ func TestEachRuleHoldsTheWantBack(t *testing.T) {
 		}
 	}
 
+	// 1126/AC-SW1, AC-SW2, AC-SW3: a want written Self while g14 was placed, kept by a rule after the placement is gone, names
+	// the controller's composition of the fingerprint the rule keeps (on 2026-10-27 g14's systemd-resolved, held, and forticlient,
+	// rule 5, kept their Self wants, which g14 could no longer compose); with no such composition, or while a record ask waits, it
+	// stays and is said; a placed node's want is Self with no composition.
+	selfAt := func(fp string) map[string]delivery.Want {
+		return map[string]delivery.Want{"ace": {FP: fNew, Composed: dig(fNew)}, "g14": {FP: fp, Self: true, Yes: dig(fp)}}
+	}
+	atF := func(_ *Module, n *Nodes) {
+		n.Haves["g14"]["mail"] = delivery.Have{FP: fNew, Composed: dig(fNew), Phase: delivery.PhaseFailed, Health: delivery.HealthOK}
+	}
+	for _, c := range []struct {
+		name   string
+		set    func(*Module, *Nodes)
+		before string
+		want   delivery.Want // the want of g14 written; zero: none written
+		rule   int           // the rule g14's holding names
+		asked  bool
+	}{
+		{name: "rule 5 at F", before: fNew, set: func(m *Module, n *Nodes) {
+			atF(m, n)
+			n.Haves["ace"]["store"] = delivery.Have{FP: fpOf('s'), Phase: delivery.PhaseRunning, Health: delivery.HealthWaits}
+		}, want: delivery.Want{FP: fNew, Composed: dig(fNew)}, rule: delivery.RuleProviders},
+		{name: "rule 3 at F", before: fNew, set: func(m *Module, n *Nodes) {
+			atF(m, n)
+			n.Haves["ace"]["mail"] = delivery.Have{FP: fOld, Phase: delivery.PhaseRunning, Health: delivery.HealthOK}
+		}, want: delivery.Want{FP: fNew, Composed: dig(fNew)}, rule: delivery.RuleCanary},
+		{name: "rule 3 held back at an older fingerprint", before: fOld, set: func(_ *Module, n *Nodes) {
+			n.Haves["ace"]["mail"] = delivery.Have{FP: fOld, Phase: delivery.PhaseRunning, Health: delivery.HealthOK}
+		}, want: delivery.Want{FP: fOld, Composed: dig(fOld), Newest: fNew, Rule: delivery.RuleCanary,
+			Words: "the canary ace does not run bbbbbbbbbbbb healthy yet"}, rule: delivery.RuleCanary},
+		{name: "held at F with nothing to set back to", before: fNew, set: func(m *Module, n *Nodes) { atF(m, n); m.Held = true },
+			want: delivery.Want{FP: fNew, Composed: dig(fNew), Words: "mail is held at bbbbbbbbbbbb and g14 ran no other fingerprint healthy to set it back to"},
+			rule: delivery.RuleNotHeld},
+		{name: "held data module", before: fNew, set: func(m *Module, n *Nodes) {
+			atF(m, n)
+			m.Held = true
+			m.Manifest.Data = &catalogue.Data{Own: []catalogue.DataItem{{ID: "mail", Class: catalogue.ClassIrreplaceable}}}
+		}, want: delivery.Want{FP: fNew, Composed: dig(fNew),
+			Words: "mail holds data, so it is not set back from bbbbbbbbbbbb: the operator is asked whether to restore it"}, rule: delivery.RuleNotHeld},
+		{name: "a record ask waits", before: fNew, set: func(m *Module, n *Nodes) {
+			atF(m, n)
+			recording(m)
+			m.Held = true
+			m.Composed = func(_, fp string) (delivery.ComposedDigest, bool) {
+				return delivery.ComposedDigest{Digest: dig(fp), Judgement: delivery.JudgedRecreates, Against: dig(fOld)}, true
+			}
+		}, rule: delivery.RuleNotHeld, asked: true},
+		{name: "no composition of F", before: fNew, set: func(m *Module, n *Nodes) {
+			atF(m, n)
+			m.Composed = func(node, fp string) (delivery.ComposedDigest, bool) {
+				if node == "g14" {
+					return delivery.ComposedDigest{}, false
+				}
+				return composedEverywhere(node, fp)
+			}
+		}, rule: delivery.RuleComposed},
+		{name: "placed", before: fNew, set: func(m *Module, n *Nodes) {
+			atF(m, n)
+			m.Self = func(node string) bool { return node == "g14" }
+			m.Composed = func(node, fp string) (delivery.ComposedDigest, bool) {
+				if node == "g14" {
+					return delivery.ComposedDigest{Judgement: delivery.JudgedNeither}, true
+				}
+				return composedEverywhere(node, fp)
+			}
+		}, want: delivery.Want{FP: fNew, Self: true}},
+	} {
+		m, n := ready()
+		c.set(&m, &n)
+		before := selfAt(c.before)
+		if c.name == "placed" {
+			before["g14"] = delivery.Want{FP: fNew, Composed: dig(fNew)}
+		}
+		out := Wants(m, n, before, nil)
+		if got := out.Wants["g14"]; got != c.want {
+			t.Errorf("%s: g14's want = %+v, want %+v", c.name, got, c.want)
+		}
+		if got := out.Rules["g14"].Rule; got != c.rule {
+			t.Errorf("%s: g14 is held by rule %d (%s), want %d", c.name, got, out.Rules["g14"].Words, c.rule)
+		}
+		if asked := len(out.Record) == 1 && out.Record[0].Node == "g14"; asked != c.asked {
+			t.Errorf("%s: record asks %+v", c.name, out.Record)
+		}
+		if w, ok := out.Wants["g14"]; ok {
+			if _, err := delivery.EncodeWant(w); err != nil {
+				t.Errorf("%s: g14's want does not encode: %v", c.name, err)
+			}
+		}
+	}
+
 	// Rule 6 per node: a grant written for the module's other nodes does not grant a node whose account it does not name
 	// (issue 1945, live on 2026-10-25 at 20:04: ace's mesh-build-go was wanted with no account on the bus).
 	m, n := ready()
@@ -150,6 +240,72 @@ func TestAFailedHealthHoldsAndSetsBack(t *testing.T) {
 	if w, ok := out.Wants["g14"]; ok && w.FP == fNew {
 		t.Errorf("g14 moved to a held fingerprint: %+v", w)
 	}
+
+	// 1496, ADR 0557 §1, §2: the same failure while F runs healthy on another node is that node's: F is not held, nothing is set
+	// back, the failing node keeps its want, and the outcome names it (on ace a newly assigned module's first check held a version healthy for an hour on three nodes).
+	n.Haves["g14"]["mail"] = delivery.Have{FP: fNew, Phase: delivery.PhaseRunning, Health: delivery.HealthOK}
+	before := map[string]delivery.Want{"ace": {FP: fNew, Composed: dig(fNew)}, "g14": {FP: fNew, Composed: dig(fNew)}}
+	out = Wants(m, n, before, map[string]string{"ace": fOld, "g14": fOld})
+	if out.Held != nil || len(out.Wants) != 0 {
+		t.Fatalf("held %+v, wants %+v: want no hold and no want changed", out.Held, out.Wants)
+	}
+	if f := out.NodeFailed["ace"]; !slices.Equal(f.Others, []string{"g14"}) || f.Words != "health failed, phase running: connection refused" ||
+		len(out.NodeFailed) != 1 {
+		t.Errorf("node failed = %+v", out.NodeFailed)
+	}
+
+	// ADR 0557 §2 (version 9): while one node fails F alone, novox, whose want names fOld, gets no new want naming F; the wants
+	// at F stay. The canary ace runs F healthy here and g14 fails it, so the canary rule (3) would let novox move: only §2 holds it.
+	three := m
+	three.Nodes = []string{"ace", "g14", "novox"}
+	failedHave := n.Haves["ace"]["mail"]
+	n.Haves["ace"]["mail"], n.Haves["g14"]["mail"] = n.Haves["g14"]["mail"], failedHave
+	n.Online["novox"] = true
+	n.Haves["novox"] = map[string]delivery.Have{"mail": {FP: fOld, Phase: delivery.PhaseRunning, Health: delivery.HealthOK}}
+	before["novox"] = delivery.Want{FP: fOld, Composed: dig(fOld)}
+	out = Wants(three, n, before, map[string]string{"ace": fOld, "g14": fOld, "novox": fOld})
+	if _, alone := out.NodeFailed["g14"]; !alone {
+		t.Errorf("g14 does not fail alone: %+v", out.NodeFailed)
+	}
+	if w, written := out.Wants["novox"]; out.Held != nil || len(out.NodeFailed) != 1 || (written && w.FP == fNew) || out.Rules["novox"].Rule != delivery.RuleNotHeld {
+		t.Errorf("held %+v, node failed %+v, novox's want %+v (%+v): want novox kept off F", out.Held, out.NodeFailed, out.Wants["novox"], out.Rules["novox"])
+	}
+	if _, written := out.Wants["g14"]; written {
+		t.Errorf("g14's want at F was rewritten: %+v", out.Wants["g14"])
+	}
+	// A node that runs F healthy with no want, while g14 fails it alone, gets its want at F and is on no neither list (issue 1945).
+	n.Haves["novox"]["mail"] = delivery.Have{FP: fNew, Phase: delivery.PhaseRunning, Health: delivery.HealthOK}
+	delete(before, "novox")
+	out = Wants(three, n, before, map[string]string{"ace": fOld, "g14": fOld, "novox": fOld})
+	if w := out.Wants["novox"]; w.FP != fNew || len(out.Neither) != 0 {
+		t.Errorf("novox running F with no want: want %+v, neither %+v; want its want at F and no neither", w, out.Neither)
+	}
+	n.Haves["ace"]["mail"], n.Haves["g14"]["mail"] = failedHave, n.Haves["ace"]["mail"]
+
+	// ADR 0557 §2: a witness that is offline keeps the have it last wrote and witnesses nothing (D1); F failing on a second node is
+	// not one node's failure (D3). Either way F is held and ace is set back.
+	for _, c := range []struct {
+		name   string
+		online map[string]bool
+		novox  delivery.Health
+	}{
+		{"the witness sleeps", map[string]bool{"ace": true, "g14": false, "novox": true}, delivery.HealthOK},
+		{"F fails on a second node", map[string]bool{"ace": true, "g14": true, "novox": true}, delivery.HealthFailed},
+	} {
+		n.Online = c.online
+		n.Haves["novox"] = map[string]delivery.Have{"mail": {FP: fNew, Phase: delivery.PhaseRunning, Health: c.novox}}
+		if c.novox == delivery.HealthOK {
+			n.Haves["novox"]["mail"] = delivery.Have{FP: fOld, Phase: delivery.PhaseRunning, Health: delivery.HealthOK}
+		}
+		before["novox"] = delivery.Want{FP: fNew, Composed: dig(fNew)}
+		out = Wants(three, n, before, map[string]string{"ace": fOld, "g14": fOld, "novox": fOld})
+		if out.Held == nil || out.Held.Node != "ace" || len(out.NodeFailed) != 0 {
+			t.Errorf("%s: held %+v, node failed %+v: want F held at ace", c.name, out.Held, out.NodeFailed)
+		}
+		if w := out.Wants["ace"]; w.FP != fOld {
+			t.Errorf("%s: ace's want = %+v, want set back", c.name, w)
+		}
+	}
 }
 
 // 1297/B4: a module holding data is not set back; its want stays and says why.
@@ -427,6 +583,23 @@ func TestTheBusIsNotMovedButItsUserListRevisionIsWrittenAtOnce(t *testing.T) {
 		t.Errorf("a held bus did not take its user-list revision as a put: %+v", w)
 	}
 	m.Puts = nil
+	// 1945 (the bus bar made loud): a node that runs the bus at an old-form build and holds no want for it gets none, since only
+	// the operator's put moves the bus, and the pass says so: a holding naming the bar, and the node on neither list so its
+	// condition stays raised. A node with a live want keeps it and is not on neither list.
+	m.Composed = composedEverywhere
+	n.Haves["ace"]["mail"] = delivery.Have{FP: "b-1700000000-oldform", Phase: delivery.PhaseRunning, Health: delivery.HealthOK}
+	out = Wants(m, n, map[string]delivery.Want{"g14": {FP: fOld, Composed: dig(fOld)}}, nil)
+	if w, wrote := out.Wants["ace"]; wrote {
+		t.Errorf("the bus bar wrote ace's want %+v", w)
+	}
+	h, on := out.Neither["ace"]
+	if !on || !h.Bus || out.Rules["ace"] != h || !strings.Contains(h.Words, "only your put moves the bus") || !strings.Contains(h.Words, "ace runs b-1700000000-oldform") ||
+		!strings.Contains(h.Words, "assigner_put") {
+		t.Errorf("the barred bus on ace: neither %+v (%v), rules %+v", h, on, out.Rules["ace"])
+	}
+	if _, on := out.Neither["g14"]; on || out.Wants["g14"].FP == fNew {
+		t.Errorf("g14 has a live want: neither %+v, its want %+v", out.Neither, out.Wants["g14"])
+	}
 	stepsOfAPut(t)
 }
 

modules/mesh-delivery-assigner/manifest_test.go

@@ -7,6 +7,7 @@ import (
 	"testing"
 
 	"git.novox.be/novox/mesh-sdk/go/catalogue"
+	"git.novox.be/novox/mesh-sdk/go/delivery"
 )
 
 func load(t *testing.T) catalogue.Manifest {
@@ -32,9 +33,9 @@ func TestManifest(t *testing.T) {
 	}
 	reads := slices.Clone(m.Reads)
 	slices.Sort(reads)
-	want := []string{"mesh-build-go.steps", "mesh-controller.assignments", "mesh-controller.builds", "mesh-controller.composed", "mesh-controller.grants",
+	want := []string{"mesh-build-go.steps", "mesh-config.resolved", "mesh-controller.assignments", "mesh-controller.builds", "mesh-controller.composed", "mesh-controller.grants", "mesh-controller.lease",
 		"mesh-delivery-builder.builds", "mesh-delivery-indexer.candidates", "mesh-delivery-indexer.manifests",
-		"mesh-delivery-indexer.modules", "mesh-delivery-teller.answers", "mesh-delivery-watchman.presence", "node-engine.have"}
+		"mesh-delivery-indexer.modules", "mesh-delivery-teller.answers", "mesh-delivery-watchman.presence", "mesh-grants.grants", "node-engine.have"}
 	if !reflect.DeepEqual(reads, want) {
 		t.Errorf("reads = %v, want exactly %v", reads, want)
 	}
@@ -42,7 +43,8 @@ func TestManifest(t *testing.T) {
 	for _, s := range m.State {
 		states[s.Name] = s.History
 	}
-	if want := map[string]int{"asks": 5, "compositions": 5, "differences": 64, "puts": 20, "wants": 20}; !reflect.DeepEqual(states, want) {
+	if want := map[string]int{"asks": 5, "compositions": 5, "differences": 64, "puts": 20, "wants": 20,
+		"placement": 64, "proposals": 5, "candidates": 5, "pulses": 0}; !reflect.DeepEqual(states, want) {
 		t.Errorf("state = %v, want %v", states, want)
 	}
 	if _, ok := m.OwnSecrets["broker"]; !ok || len(m.OwnSecrets) != 1 {
@@ -57,12 +59,27 @@ func TestManifest(t *testing.T) {
 		t.Errorf("uses = %v, want exactly node-build-go and operator-channel", m.Uses)
 	}
 	// ADR 0546: it serves its own tools (put, release, puts) from its bundle through the tool runner (the artifact loads the
-	// module), claims no seat (a new seat needs a change of the controller), says each put's step as the event put, and
-	// calls the controller's warranted and the bus node's backup holder.
-	if len(m.Claims) != 0 || !slices.Equal(m.Tools, []string{"assigner_put", "assigner_release", "assigner_puts"}) {
-		t.Errorf("the assigner claims %v and serves tools %v, want no claim and its three put tools", m.Claims, m.Tools)
+	// module), says each put's step as the event put, and calls the controller's warranted and the bus node's backup holder.
+	// ADR 0567 §1, §6-§10: it holds the seat mesh-placement, serving its seven verbs; keeps the seat's events on its stream
+	// placement for 30 days; calls the controller's export, its four verbs that keep its assignments in step and its
+	// hand-act log; and reads mesh-config's resolved values to compose every node a proposal touches.
+	if len(m.Claims) != 1 || m.Claims[0].Name != catalogue.PlacementSeat || m.Claims[0].At() != catalogue.ScopeMesh ||
+		!slices.Equal(m.Claims[0].Serves, []string{"placement", "proposals", "propose", "withdraw", "again", "adopt", "hand-back"}) {
+		t.Errorf("the assigner claims %+v, want mesh-placement with its seven verbs", m.Claims)
 	}
-	if want := []string{"seat:mesh-controller.warranted", "seat:node-backup.backed-up", "seat:node-backup.now"}; !slices.Equal(slices.Sorted(slices.Values(m.Invokes)), want) {
+	if seat, _ := catalogue.SeatNamed(catalogue.PlacementSeat); catalogue.CanHold(m, seat) != nil {
+		t.Errorf("the assigner cannot hold the seat: %v", catalogue.CanHold(m, seat))
+	}
+	if !slices.Equal(m.Tools, []string{"assigner_put", "assigner_release", "assigner_puts"}) {
+		t.Errorf("the assigner serves tools %v, want its three put tools", m.Tools)
+	}
+	if len(m.Streams) != 1 || m.Streams[0].Name != delivery.PlacementStream || m.Streams[0].MaxAgeDays != delivery.PlacementStreamDays ||
+		!slices.Equal(slices.Sorted(slices.Values(m.Streams[0].Events)), slices.Sorted(slices.Values(delivery.PlacementEvents))) {
+		t.Errorf("streams = %+v, want placement carrying the seat's four events for %d days", m.Streams, delivery.PlacementStreamDays)
+	}
+	if want := []string{"seat:mesh-controller.assign", "seat:mesh-controller.hand-act", "seat:mesh-controller.pin",
+		"seat:mesh-controller.placement-export", "seat:mesh-controller.unassign", "seat:mesh-controller.unpin",
+		"seat:mesh-controller.warranted", "seat:node-backup.backed-up", "seat:node-backup.now"}; !slices.Equal(slices.Sorted(slices.Values(m.Invokes)), want) {
 		t.Errorf("invokes = %v, want %v", m.Invokes, want)
 	}
 	if !slices.Equal(m.Emits, []string{"put"}) {

modules/mesh-delivery-assigner/module.json

@@ -2,18 +2,36 @@
   "module": "mesh-delivery-assigner",
   "version": "1",
   "slug": "assigner",
+  "claims": [
+    {
+      "name": "mesh-placement",
+      "scope": "mesh",
+      "serves": [
+        "placement",
+        "proposals",
+        "propose",
+        "withdraw",
+        "again",
+        "adopt",
+        "hand-back"
+      ]
+    }
+  ],
   "reads": [
     "mesh-build-go.steps",
+    "mesh-config.resolved",
     "mesh-controller.assignments",
     "mesh-controller.builds",
     "mesh-controller.composed",
     "mesh-controller.grants",
+    "mesh-controller.lease",
     "mesh-delivery-builder.builds",
     "mesh-delivery-indexer.candidates",
     "mesh-delivery-indexer.manifests",
     "mesh-delivery-indexer.modules",
     "mesh-delivery-teller.answers",
     "mesh-delivery-watchman.presence",
+    "mesh-grants.grants",
     "node-engine.have"
   ],
   "uses": [
@@ -21,9 +39,15 @@
     "operator-channel"
   ],
   "invokes": [
+    "seat:mesh-controller.assign",
+    "seat:mesh-controller.hand-act",
+    "seat:mesh-controller.pin",
+    "seat:mesh-controller.placement-export",
+    "seat:mesh-controller.unassign",
+    "seat:mesh-controller.unpin",
     "seat:mesh-controller.warranted",
-    "seat:node-backup.now",
-    "seat:node-backup.backed-up"
+    "seat:node-backup.backed-up",
+    "seat:node-backup.now"
   ],
   "emits": [
     "put"
@@ -34,12 +58,28 @@
     "assigner_puts"
   ],
   "state": [
+    { "name": "placement", "history": 64 },
+    { "name": "proposals", "history": 5 },
+    { "name": "candidates", "history": 5 },
+    { "name": "pulses", "key-ttl": true },
     { "name": "asks", "history": 5 },
     { "name": "compositions", "history": 5 },
     { "name": "differences", "history": 64 },
     { "name": "puts", "history": 20 },
     { "name": "wants", "history": 20 }
   ],
+  "streams": [
+    {
+      "name": "placement",
+      "events": [
+        "placement-proposed",
+        "placement-judged",
+        "placement-changed",
+        "placement-withdrawn"
+      ],
+      "max-age-days": 30
+    }
+  ],
   "own-secrets": {
     "broker": "${dir:state}/broker"
   },

modules/mesh-delivery-builder/cmd/mesh-delivery-builder-tools/main.go

@@ -7,6 +7,7 @@ package main
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"os"
 	"strings"
@@ -15,6 +16,7 @@ import (
 
 	stdio "git.novox.be/novox/mesh-sdk/go"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
+	"git.novox.be/novox/mesh-sdk/go/delivery/buildrun"
 
 	"mesh-delivery-builder/internal/build"
 )
@@ -23,15 +25,16 @@ import (
 type queueAsker func(key string, value []byte) (json.RawMessage, error)
 
 // Tools are the builder's tools: stuck reads, askAgain writes the reasks value, queue writes a queues value and waits for
-// the builder's read.
-func Tools(r build.StuckReader, askAgain func(key string, value []byte) error, queue queueAsker, now func() time.Time) []stdio.Tool {
+// the builder's read, buildAgain writes a reasks value of mode build and waits for the builder's answer.
+func Tools(r build.StuckReader, askAgain func(key string, value []byte) error, queue, buildAgain queueAsker, now func() time.Time) []stdio.Tool {
 	str := func(args map[string]any, k string) string { s, _ := args[k].(string); return strings.TrimSpace(s) }
 	return []stdio.Tool{
 		{Name: build.StuckTool,
 			Description: "Every build key that waits (building or queued), oldest first: its module, fingerprint, step words and since when, and each ask it " +
 				"waits on by language with its id, when it was put, its asking (1 for the first; the builder asks an ask again when it can no longer be " +
 				"answered, at most 3 times) and what its build module's steps hold of it (none, or its state on its node since its start). The " +
-				"seat workers' delivery counts are not readable by the builder. With module, that module's keys only. Read-only.",
+				"seat workers' delivery counts are not readable by the builder. dead_letters says whether the builder hears the asks the build seats give up " +
+				"on (issue 734), and why not: heard, a given-up ask is asked again at once; deaf, at its check bound. With module, that module's keys only. Read-only.",
 			Input: map[string]any{"type": "object", "properties": map[string]any{
 				"module": map[string]any{"type": "string", "description": "only this module's keys"}}},
 			Run: func(args map[string]any) (any, error) { return r.Stuck(str(args, "module")) }},
@@ -55,6 +58,42 @@ func Tools(r build.StuckReader, askAgain func(key string, value []byte) error, q
 				return map[string]any{"key": key, "asked": true,
 					"next": "the builder answers in " + build.ReAsksState + "." + key + "; " + build.StuckTool + " shows the answer and the new ask"}, nil
 			}},
+		{Name: build.BuildAgainTool,
+			Description: "Build a failed key again (rebuild a module, build a failed key again): the builder writes the key of module and " +
+				"fingerprint building as a new revision of the same key and asks the build seats, as it does by itself when it looks at a module " +
+				"again (ADR 0429 clause 18). Answers the new revision and the ask id of each build module (go, node, image). Refuses a key that " +
+				"is not failed, and says why: done (nothing to do), or waiting (building or queued: " + build.AskAgainTool + " asks its waiting asks " +
+				"again); a key failed for a reason the builder never retries on the same fingerprint (a pin missing, a version taken, digests that " +
+				"differ) and a fingerprint its module no longer has are refused too. Use it for a key builder_stuck does not show, which failed.",
+			Input: map[string]any{"type": "object", "required": []string{"module", "fp", "why"}, "properties": map[string]any{
+				"module": map[string]any{"type": "string", "description": "the module's name"},
+				"fp":     map[string]any{"type": "string", "description": "its new-form fingerprint, src2:<hex>"},
+				"why":    map[string]any{"type": "string", "description": "why it is built again, in plain words"}}},
+			Run: func(args map[string]any) (any, error) {
+				key, value, err := build.NewBuildAgain(str(args, "module"), str(args, "fp"), str(args, "why"), stdio.CallerOf(args), now())
+				if err != nil {
+					return nil, err
+				}
+				raw, err := buildAgain(key, value)
+				if err != nil {
+					return nil, err
+				}
+				r, err := build.DecodeReAsk(raw)
+				if err != nil {
+					return nil, err
+				}
+				if r.Refused {
+					return nil, errors.New(r.Answer)
+				}
+				if r.Failed != "" {
+					return nil, errors.New(r.Answer)
+				}
+				if r.Revision == 0 && !r.Pending {
+					return nil, fmt.Errorf("the builder answered neither a new revision nor a refusal (an older builder?): %s", r.Answer)
+				}
+				return map[string]any{"key": key, "revision": r.Revision, "asks": r.Asks, "answer": r.Answer,
+					"next": build.StuckTool + " shows the key and its asks while they wait"}, nil
+			}},
 		{Name: build.SeatQueueTool,
 			Description: "What waits on a build seat's stream (SEAT_NODE_BUILD_<LANGUAGE>), as the builder reads it: the stream's message count and " +
 				"sequences, and per kind (delivery, check, recheck) its messages oldest first, at most limit each, with sequence, ask id, when asked " +
@@ -85,8 +124,17 @@ func Tools(r build.StuckReader, askAgain func(key string, value []byte) error, q
 
 // askQueue writes the queues value at key and waits, on a watch of the key, at most bound for the builder's answer.
 func askQueue(s stdio.KeptState, bound time.Duration) queueAsker {
+	return askKept(s, build.QueuesState, build.QueuesBucket, "the read", bound, func(v []byte) bool {
+		a, err := build.DecodeQueueAsk(v)
+		return err == nil && !a.Answered.IsZero()
+	})
+}
+
+// askKept writes a value at key of a state the builder watches and answers there, and waits, on a watch of the key, at most
+// bound for a value written after it that answered says is the builder's answer.
+func askKept(s stdio.KeptState, state, bucket, what string, bound time.Duration, answered func([]byte) bool) queueAsker {
 	return func(key string, value []byte) (json.RawMessage, error) {
-		answered := make(chan json.RawMessage, 1)
+		heard := make(chan json.RawMessage, 1)
 		var rev uint64
 		var mu sync.Mutex
 		if err := s.Watch(key, func(c stdio.StateChange) error {
@@ -96,36 +144,34 @@ func askQueue(s stdio.KeptState, bound time.Duration) queueAsker {
 			if c.Op != "put" || mine == 0 || c.Revision <= mine {
 				return nil
 			}
-			if a, err := build.DecodeQueueAsk(c.Value); err == nil && !a.Answered.IsZero() {
+			if answered(c.Value) {
 				select {
-				case answered <- c.Value:
+				case heard <- c.Value:
 				default:
 				}
 			}
 			return nil
 		}); err != nil {
-			return nil, fmt.Errorf("watching %s.%s: %w", build.QueuesState, key, err)
+			return nil, fmt.Errorf("watching %s.%s: %w", state, key, err)
 		}
 		r, err := s.Put(key, json.RawMessage(value))
 		if err != nil {
-			return nil, fmt.Errorf("the read could not be written to %s: %w", build.QueuesBucket, err)
+			return nil, fmt.Errorf("%s could not be written to %s: %w", what, bucket, err)
 		}
 		mu.Lock()
 		rev = r
 		mu.Unlock()
 		// The watch may have heard the answer before the revision was known: read it once too.
-		if e, err := s.Get(key); err == nil && e != nil && e.Revision > r {
-			if a, err := build.DecodeQueueAsk(e.Value); err == nil && !a.Answered.IsZero() {
-				return e.Value, nil
-			}
+		if e, err := s.Get(key); err == nil && e != nil && e.Revision > r && answered(e.Value) {
+			return e.Value, nil
 		}
 		wait, cancel := context.WithTimeout(context.Background(), bound) // a context's bound, no timer (ADR 0437 §8)
 		defer cancel()
 		select {
-		case v := <-answered:
+		case v := <-heard:
 			return v, nil
 		case <-wait.Done():
-			return nil, fmt.Errorf("the builder did not answer %s.%s within %s: it is not running, or cannot read %s", build.QueuesState, key, bound, build.QueuesBucket)
+			return nil, fmt.Errorf("the builder did not answer %s.%s within %s: it is not running, or cannot read %s", state, key, bound, bucket)
 		}
 	}
 }
@@ -166,12 +212,17 @@ func main() {
 		steps[bm] = read(stdio.State(bm + ".steps"))
 	}
 	reasks := stdio.State(build.ReAsksState)
-	r := build.StuckReader{Logf: func(f string, a ...any) { fmt.Fprintf(os.Stderr, "[mesh-delivery-builder-tools] "+f+"\n", a...) }, Builds: read(stdio.State("builds")), ReAsks: read(reasks), Steps: steps}
+	r := build.StuckReader{Logf: func(f string, a ...any) { fmt.Fprintf(os.Stderr, "[mesh-delivery-builder-tools] "+f+"\n", a...) }, Builds: read(stdio.State("builds")), ReAsks: read(reasks), Steps: steps,
+		Hearing: read(stdio.State(buildrun.HearingState))}
 	put := func(key string, value []byte) error {
 		_, err := reasks.Put(key, json.RawMessage(value))
 		return err
 	}
-	if err := stdio.Serve("", Tools(r, put, askQueue(stdio.State(build.QueuesState), 25*time.Second), time.Now)); err != nil {
+	buildAgain := askKept(reasks, build.ReAsksState, build.ReAsksBucket, "the request", 25*time.Second, func(v []byte) bool {
+		a, err := build.DecodeReAsk(v)
+		return err == nil && !a.Answered.IsZero()
+	})
+	if err := stdio.Serve("", Tools(r, put, askQueue(stdio.State(build.QueuesState), 25*time.Second), buildAgain, time.Now)); err != nil {
 		fmt.Fprintf(os.Stderr, "[mesh-delivery-builder-tools] %v\n", err)
 		os.Exit(1)
 	}

modules/mesh-delivery-builder/cmd/mesh-delivery-builder/integration_test.go

@@ -24,6 +24,7 @@ import (
 
 	"git.novox.be/novox/mesh-sdk/go/buildstep"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
+	"git.novox.be/novox/mesh-sdk/go/process"
 
 	"mesh-delivery-builder/internal/build"
 )
@@ -345,7 +346,7 @@ func (b *bed) archive(t *testing.T, name, path, at string) string {
 func (b *bed) start(t *testing.T, node string, env map[string]string) {
 	t.Helper()
 	broker := filepath.Join(t.TempDir(), "broker")
-	cred, _ := json.Marshal(credential{URL: b.srvURL, Node: node, Module: "mesh-delivery-builder", User: node + ".mesh-delivery-builder", Password: "pw"})
+	cred, _ := json.Marshal(process.Account{URL: b.srvURL, Node: node, Module: "mesh-delivery-builder", User: node + ".mesh-delivery-builder", Password: "pw"})
 	if err := os.WriteFile(broker, cred, 0o600); err != nil {
 		t.Fatal(err)
 	}

modules/mesh-delivery-builder/cmd/mesh-delivery-builder/main.go

@@ -6,12 +6,6 @@ package main
 
 import (
 	"context"
-	"crypto/sha256"
-	"crypto/tls"
-	"crypto/x509"
-	"encoding/hex"
-	"encoding/json"
-	"errors"
 	"fmt"
 	"io"
 	"log"
@@ -51,80 +45,18 @@ func main() {
 	}
 }
 
-// credential is the broker file the controller issues to the module: JSON of the bus address, the certificate
-// fingerprint to pin, the principal and its password (as the indexer reads it; issue 1242 moves this into the SDK).
-type credential struct {
-	URL         string `json:"url"`
-	Fingerprint string `json:"fingerprint"`
-	Node        string `json:"node"`
-	Module      string `json:"module"`
-	User        string `json:"user"`
-	Password    string `json:"password"`
-}
-
-func readCredential(path string) (credential, error) {
-	raw, err := os.ReadFile(path)
-	if err != nil {
-		return credential{}, err
-	}
-	var c credential
-	if err := json.Unmarshal(raw, &c); err != nil {
-		return credential{}, fmt.Errorf("the broker credential is not one: %w", err)
-	}
-	if c.URL == "" || c.User == "" {
-		return credential{}, errors.New("the broker credential names no bus address or user")
-	}
-	return c, nil
-}
-
-// pinned accepts exactly the certificate with this SHA-256 and no other.
-func pinned(want string) *tls.Config {
-	return &tls.Config{
-		InsecureSkipVerify: true, //nolint:gosec // replaced by the pin below, which is stricter
-		MinVersion:         tls.VersionTLS12,
-		VerifyPeerCertificate: func(rawCerts [][]byte, _ [][]*x509.Certificate) error {
-			if len(rawCerts) == 0 {
-				return errors.New("the bus presented no certificate")
-			}
-			sum := sha256.Sum256(rawCerts[0])
-			if got := "sha256:" + hex.EncodeToString(sum[:]); got != want {
-				return fmt.Errorf("the bus presented a certificate this mesh does not know (%.23s…)", got)
-			}
-			return nil
-		},
-	}
-}
-
 // run is the program: it returns when ctx ends or the bus cannot be used.
 func run(ctx context.Context, getenv func(string) string, logOut io.Writer) error {
 	logger := log.New(logOut, "mesh-delivery-builder: ", log.LstdFlags)
-	path := strings.TrimSpace(getenv("MESH_BROKER_FILE"))
-	if path == "" {
-		return errors.New("MESH_BROKER_FILE is not set, so there is no credential to hear the bus with")
-	}
-	cred, err := readCredential(path)
+	cred, err := process.ReadBrokerAccount(getenv)
 	if err != nil {
 		return err
 	}
-	opts := []nats.Option{
-		nats.Name(cred.Node + "." + cred.Module),
-		nats.UserInfo(cred.User, cred.Password),
-		nats.CustomInboxPrefix("_INBOX." + cred.User),
-		nats.MaxReconnects(-1),
-		nats.RetryOnFailedConnect(true),
-	}
-	if strings.TrimSpace(cred.Fingerprint) != "" {
-		opts = append(opts, nats.Secure(pinned(cred.Fingerprint)))
-	}
-	conn, err := nats.Connect(cred.URL, opts...)
+	conn, js, err := cred.Dial()
 	if err != nil {
-		return fmt.Errorf("connecting to the bus: %w", err)
+		return err
 	}
 	defer conn.Close()
-	js, err := jetstream.New(conn)
-	if err != nil {
-		return err
-	}
 	builds, err := process.EssentialBucket(ctx, js, "builder", delivery.BuilderBuildsBucket, "claim or write a build key")
 	if err != nil {
 		return err
@@ -149,20 +81,37 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 	// Each build module's part of a build is an ask on its build seat's stream, pulled by a build node with a free slot
 	// (novox/hq ADR 0525): the builder chooses no node, so it reads neither presence nor have and holds no capacity.
 	asks := buildrun.JetStreamAsks{JS: js}
+	// The asks the build seats gave up on (issue 734): heard from DEAD_LETTERS, each ends the wait for its step at once,
+	// and the lane asks its part again (Builder.waitOnce) instead of waiting for the check bound.
+	// Heard in the background, and again at a reconnect or an ask while it is not; whether it is heard is kept in the
+	// state hearing, which builder_stuck says (dead_letters).
+	dead := &buildrun.DeadLetters{}
+	// The state may not be on the bus yet when a delivery started the builder (the grants part creates it, issue 1790): it
+	// is bound when the bus says it was created, and the latest hearing is written then.
+	hearingKV := process.AwaitBucket(ctx, js, conn, delivery.BuilderModule+"_"+buildrun.HearingState, "builder_stuck cannot say whether DEAD_LETTERS is heard", logger.Printf)
+	hearing := buildrun.NewDeadLetterHearing(ctx, buildrun.JetStreamDeadLetters{JS: js}, delivery.AskLanguages, dead, logger.Printf,
+		buildrun.SayHearing(ctx, hearingKV, logger.Printf))
+	defer hearing.Stop()
+	// Each ask's step is heard by its own watch and, at every step end of its build module and every reconnect, read
+	// (buildrun.HearEnds): a watch that goes deaf loses no end (the lost check of 2026-10-28).
+	var buildModules []string
+	for _, l := range delivery.AskLanguages {
+		if m, err := delivery.BuildModuleOf(l); err == nil {
+			buildModules = append(buildModules, m)
+		}
+	}
+	heard := buildrun.HearEnds(ctx, asks, asks, buildModules, logger.Printf)
+	conn.SetReconnectHandler(func(*nats.Conn) { hearing.Again(); heard.Nudge("") })
 	// The builder asks the controller, as its own account, whether the artifact store still holds a done key's blobs
 	// (the seat verb held, novox/hq issue 1937) before it leaves the key done.
-	account, err := process.ReadAccount(path)
-	if err != nil {
-		return err
-	}
-	calls, err := process.Connect(account, nats.Name(cred.Node+"."+cred.Module+".calls"), nats.RetryOnFailedConnect(true))
+	calls, err := process.Connect(cred, nats.Name(cred.Node+"."+cred.Module+".calls"), nats.RetryOnFailedConnect(true))
 	if err != nil {
 		return err
 	}
 	defer calls.Close()
 	b := &build.Builder{
 		Claimer: build.Claimer{Store: kvStore{builds}, By: cred.Node + "." + cred.Module},
-		Asks:    buildrun.Asker{Publisher: asks, Waiter: asks, Bound: bound},
+		Asks:    buildrun.Asker{Publisher: asks, Waiter: buildrun.LostAskWaiter{Inner: heard, Dead: dead, Hearing: hearing}, Bound: bound},
 		Held:    heldOnTheBus{js},
 		// An ask that can no longer be answered is asked again (issue 1945), read at the step bound: a context's bound.
 		Gone:       heldOnTheBus{js},
@@ -204,11 +153,11 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 	}
 	// The toolchains first, so a build that starts from the first modules value finds the nodes.
 	watch := newToolchainWatch(ctx, js, tools, b.NodesChanged, logger)
-	// Only the toolchain reports of nodes the build module is assigned to count (issue 1940): the controller's
-	// assignments are settled first, so the toolchains settle through the gate already knowing them.
-	gate := newToolchainGate([]string{buildrun.GoBuildModule, buildrun.NodeBuildModule}, tools.Put, logger.Printf)
+	// Only the toolchain reports of nodes the catalogue places the build module on count (issue 1940, ADR 0549 §3): the
+	// placement is settled first, so the toolchains settle through the gate already knowing it.
+	gate := buildrun.NewToolchainGate([]string{buildrun.GoBuildModule, buildrun.NodeBuildModule}, tools.Put, logger.Printf)
 	watch.put = gate.Toolchain
-	assignErrs, err := watchAssignments(ctx, js, gate, b.NodesChanged, logger)
+	placementErrs, err := buildrun.FollowPlacement(ctx, js, gate, b.NodesChanged, logger.Printf)
 	if err != nil {
 		return err
 	}
@@ -220,13 +169,12 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 	// module.
 	for _, module := range []string{buildrun.GoBuildModule, buildrun.NodeBuildModule} {
 		stream := toolchainStreams[module]
-		cons, err := js.Consumer(ctx, stream, cred.Node+"_"+cred.Module)
+		cons, err := cred.EventConsumer(ctx, js, stream)
 		if err != nil {
 			logger.Printf("the consumer %s_%s on %s does not exist yet, so %s's reports are not heard until the builder starts again: %v", cred.Node, cred.Module, stream, module, err)
 			continue
 		}
-		cc, err := cons.Consume(func(m jetstream.Msg) { watch.Reported(m) },
-			jetstream.ConsumeErrHandler(func(_ jetstream.ConsumeContext, err error) { logger.Printf("hearing the bus: %v", err) }))
+		cc, err := process.HearEvents(cons, func(m jetstream.Msg) { watch.Reported(m) }, logger.Printf)
 		if err != nil {
 			return err
 		}
@@ -235,13 +183,12 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 	// The controller says artifacts-gone when its take-in found a key's blob gone (issue 1937): the builder's durable
 	// consumer on EVENTS, made by the controller from the manifest's consumes. Where it is not there yet the builder says
 	// so; it still asks held at its start and at every module value.
-	switch cons, err := js.Consumer(ctx, eventsStream, cred.Node+"_"+cred.Module); {
+	switch cons, err := cred.EventConsumer(ctx, js, eventsStream); {
 	case err != nil:
 		logger.Printf("the consumer %s_%s on %s does not exist yet, so %s is not heard until the builder starts again: %v",
 			cred.Node, cred.Module, eventsStream, delivery.ArtifactsGoneEvent, err)
 	default:
-		cc, err := cons.Consume(func(m jetstream.Msg) { heardGone(ctx, b, m, logger.Printf) },
-			jetstream.ConsumeErrHandler(func(_ jetstream.ConsumeContext, err error) { logger.Printf("hearing the bus: %v", err) }))
+		cc, err := process.HearEvents(cons, func(m jetstream.Msg) { heardGone(ctx, b, m, logger.Printf) }, logger.Printf)
 		if err != nil {
 			return err
 		}
@@ -280,24 +227,25 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 	}
 	// A person asks a key's build again with builder_ask_again, which writes the reasks state (issue 1945): watched, as
 	// every other input. The builder asks again by itself without it.
-	if kv := process.OptionalBucket(ctx, js, build.ReAsksBucket, "builder_ask_again is not heard until the builder starts again; an ask that can no longer be answered is still asked again by itself", logger.Printf); kv != nil {
+	// A state not on the bus yet at this start is watched once it appears (issue 1790).
+	process.AwaitBucket(ctx, js, conn, build.ReAsksBucket, "builder_ask_again is not heard; an ask that can no longer be answered is still asked again by itself", logger.Printf).Ready(func(kv jetstream.KeyValue) {
 		eachReAsk := func(e jetstream.KeyValueEntry) { reAsked(ctx, b, kv, e, logger.Printf) }
 		if rw, err := settle(ctx, kv, eachReAsk); err != nil {
 			process.NotWatched(logger.Printf, build.ReAsksBucket, err, "builder_ask_again is not heard until the builder starts again")
 		} else {
 			go func() { errs <- follow(ctx, rw, eachReAsk) }()
 		}
-	}
+	})
 	// A person reads a build seat's stream with builder_seat_queue, which writes the queues state (issue 1945 note 62): the
 	// builder alone may read the stream, so it answers there.
-	if kv := process.OptionalBucket(ctx, js, build.QueuesBucket, "builder_seat_queue is not answered until the builder starts again", logger.Printf); kv != nil {
+	process.AwaitBucket(ctx, js, conn, build.QueuesBucket, "builder_seat_queue is not answered", logger.Printf).Ready(func(kv jetstream.KeyValue) {
 		eachRead := func(e jetstream.KeyValueEntry) { queueRead(ctx, heldOnTheBus{js}, kv, e, logger.Printf) }
 		if qw, err := settle(ctx, kv, eachRead); err != nil {
 			process.NotWatched(logger.Printf, build.QueuesBucket, err, "builder_seat_queue is not answered until the builder starts again")
 		} else {
 			go func() { errs <- follow(ctx, qw, eachRead) }()
 		}
-	}
+	})
 	logger.Printf("started on %s", cred.Node)
 	go func() { errs <- follow(ctx, w, each) }()
 	select {
@@ -306,7 +254,7 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 		return nil
 	case err := <-errs:
 		return err
-	case err := <-assignErrs:
+	case err := <-placementErrs:
 		return err
 	case err := <-watch.errs:
 		return err

modules/mesh-delivery-builder/cmd/mesh-delivery-builder/reasks.go

@@ -8,6 +8,7 @@ import (
 	"strings"
 	"time"
 
+	"git.novox.be/novox/mesh-sdk/go/process"
 	"github.com/nats-io/nats.go"
 	"github.com/nats-io/nats.go/jetstream"
 
@@ -17,8 +18,13 @@ import (
 // askAgainer is the part of the builder a reasks value asks through.
 type askAgainer interface {
 	AskAgain(key, why string) []string
+	BuildAgain(ctx context.Context, module, fp, why, by string, bound time.Duration) build.BuildAgainResult
 }
 
+// buildAgainBound is how long the builder waits for the claim and the asks of a key built again by hand; the tool waits
+// longer for the builder's answer.
+const buildAgainBound = 15 * time.Second
+
 // reAsked answers one value of the reasks state (the tool builder_ask_again, issue 1945): a value not yet answered asks the
 // key's waiting lanes again and is written back, by compare-and-set at its revision, with what the builder did. A value
 // answered already (this builder's own write) or deleted is left.
@@ -34,6 +40,11 @@ func reAsked(ctx context.Context, b askAgainer, kv jetstream.KeyValue, e jetstre
 	if r.Answer != "" {
 		return
 	}
+	if r.Mode == build.ModeBuild {
+		// The answer comes when the claim and the asks are written, so it is made beside the watch, not in it.
+		go builtAgain(ctx, b, kv, e, r, logf)
+		return
+	}
 	asked := b.AskAgain(e.Key(), r.Why)
 	if len(asked) == 0 {
 		r.Answer = "no ask of this key waits in this builder now (it is not building, or its build has not reached its ask yet): nothing was asked; builder_stuck shows where it stands"
@@ -53,12 +64,12 @@ func reAsked(ctx context.Context, b askAgainer, kv jetstream.KeyValue, e jetstre
 
 // emitAskedAgain says the builder's event build.asked-again (issue 1945): mesh.mod.<module>.event.build.asked-again,
 // with the SDK's envelope headers and the new ask's id as the bus's dedup id.
-func emitAskedAgain(ctx context.Context, js jetstream.JetStream, cred credential, e build.AskedAgain) error {
+func emitAskedAgain(ctx context.Context, js jetstream.JetStream, cred process.Account, e build.AskedAgain) error {
 	data, err := json.Marshal(e)
 	if err != nil {
 		return err
 	}
-	msg := nats.NewMsg("mesh.mod." + cred.Module + ".event." + build.AskedAgainEvent)
+	msg := nats.NewMsg(cred.EventSubject(build.AskedAgainEvent))
 	id := "asked-again-" + e.New
 	msg.Header.Set("x-event-id", id)
 	msg.Header.Set("x-source", cred.Module)
@@ -73,3 +84,33 @@ func emitAskedAgain(ctx context.Context, js jetstream.JetStream, cred credential
 	}
 	return nil
 }
+
+// builtAgain answers a reasks value of mode build (the tool builder_build_again, issue 1126 note 72): the failed key is
+// built again as a new revision, and the value is written back with the revision and the asks put, or why nothing was done.
+func builtAgain(ctx context.Context, b askAgainer, kv jetstream.KeyValue, e jetstream.KeyValueEntry, r build.ReAsk, logf func(string, ...any)) {
+	res := b.BuildAgain(ctx, r.Module, r.FP, r.Why, r.By, buildAgainBound)
+	switch {
+	case res.Refused != "":
+		r.Answer, r.Refused = res.Refused, true
+	case res.Failed != "":
+		r.Answer, r.Revision, r.Failed = fmt.Sprintf("the key is written building as revision %d, and the build failed before any ask was put: %s", res.Revision, res.Failed), res.Revision, res.Failed
+	default:
+		r.Pending = res.Revision == 0
+		r.Answer, r.Revision, r.Asks = "built again: the key is written building as revision "+fmt.Sprint(res.Revision)+" and its asks are put", res.Revision, res.Asks
+		if res.Pending != "" {
+			r.Answer = res.Pending
+			if res.Revision != 0 {
+				r.Answer = "built again: the key is written building as revision " + fmt.Sprint(res.Revision) + "; " + res.Pending
+			}
+		}
+	}
+	r.Answered = time.Now().UTC()
+	logf("%s: build again asked by %s (%s): %s", e.Key(), r.By, r.Why, r.Answer)
+	data, err := json.Marshal(r)
+	if err != nil {
+		return
+	}
+	if _, err := kv.Update(ctx, e.Key(), data, e.Revision()); err != nil && !errors.Is(err, jetstream.ErrKeyExists) && !errors.Is(err, jetstream.ErrKeyRevisionMismatch) {
+		logf("%s.%s: the answer could not be written: %v", build.ReAsksState, e.Key(), err)
+	}
+}

modules/mesh-delivery-builder/cmd/mesh-delivery-builder/refused_test.go

@@ -0,0 +1,73 @@
+package main
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"log"
+	"strings"
+	"testing"
+
+	"git.novox.be/novox/mesh-sdk/go/process"
+
+	"github.com/nats-io/nats.go/jetstream"
+
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+	"git.novox.be/novox/mesh-sdk/go/delivery/buildrun"
+)
+
+// 1945 (a part exits at start for a bucket it works without): a bus that refuses every toolchains bucket leaves the
+// watch unstarted and the part running, said; a refused bucket it cannot work without is an error naming the bucket and
+// its grant. The gate over the seat's placement, and its refusal, are mesh-sdk's (buildrun.ToolchainGate,
+// issue 774).
+func TestARefusedBucketIsSaidAndThePartGoesOn(t *testing.T) {
+	set := &buildrun.ToolchainSet{}
+	var logs bytes.Buffer
+	logger := log.New(&logs, "", 0)
+	refused := refusingBus{err: errors.New("nats: permissions violation for publish to $JS.API.CONSUMER.CREATE.KV_mesh-build-node_toolchains")}
+	if err := newToolchainWatch(context.Background(), refusingBus{refuseOpen: true, err: refused.err}, set, func(context.Context) {}, logger).start(); err != nil {
+		t.Errorf("a refused toolchains bucket stopped the start: %v", err)
+	}
+	if !strings.Contains(logs.String(), "cannot be read") {
+		t.Errorf("the refusals were not said: %q", logs.String())
+	}
+	if _, err := process.EssentialBucket(context.Background(), refusingBus{refuseOpen: true, err: refused.err}, "builder", "mesh-delivery-indexer_modules", "work"); err == nil ||
+		!strings.Contains(err.Error(), "grant of mesh-delivery-indexer_modules") {
+		t.Errorf("a refused bucket the part needs: %v, want an error naming its grant", err)
+	}
+	// The gate's source (the previews' trunk heads): refused at start, the builder goes on, and a candidate asking a trunk
+	// head is told why and opens it again then.
+	src := &trunkSource{ctx: context.Background(), js: refusingBus{refuseOpen: true, err: refused.err}, heads: &sourceHeads{}, errs: make(chan error, 1), logf: logger.Printf}
+	src.start()
+	if _, err := src.head(context.Background(), 7, "novox/mesh-catalog"); err == nil || !strings.Contains(err.Error(), delivery.SourceBucket) {
+		t.Errorf("a trunk head with the source refused: %v, want why", err)
+	}
+	if src.opened {
+		t.Error("a refused source counts as opened, so it is never opened again")
+	}
+}
+
+// refusingBus is a bus that refuses: every open (refuseOpen), or every watch of a bucket it opens, with err.
+type refusingBus struct {
+	refuseOpen bool
+	err        error
+}
+
+func (r refusingBus) KeyValue(context.Context, string) (jetstream.KeyValue, error) {
+	if r.refuseOpen {
+		return nil, r.err
+	}
+	return refusedWatch{err: r.err}, nil
+}
+
+type refusedWatch struct {
+	jetstream.KeyValue
+	err error
+}
+
+func (r refusedWatch) WatchAll(context.Context, ...jetstream.WatchOpt) (jetstream.KeyWatcher, error) {
+	return nil, r.err
+}
+func (r refusedWatch) Watch(context.Context, string, ...jetstream.WatchOpt) (jetstream.KeyWatcher, error) {
+	return nil, r.err
+}

modules/mesh-delivery-builder/cmd/mesh-delivery-builder/standing.go

@@ -1,211 +0,0 @@
-package main
-
-// This file is the same in mesh-delivery-indexer, mesh-delivery-builder and mesh-delivery-checker (issue 1940): it moves
-// to mesh-sdk go/delivery/buildrun once mesh-sdk can be delivered again, since a change of mesh-sdk waits on the very
-// toolchain agreement this file repairs.
-
-import (
-	"context"
-	"encoding/json"
-	"fmt"
-	"log"
-	"maps"
-	"slices"
-	"strings"
-	"sync"
-	"time"
-
-	"github.com/nats-io/nats.go/jetstream"
-
-	"git.novox.be/novox/mesh-sdk/go/delivery"
-	"git.novox.be/novox/mesh-sdk/go/provider"
-)
-
-// A build module writes <node>.<language> of its toolchains state on every node it runs on, and nothing deletes the key
-// when the module is unassigned from a node: the controller writes no module's state, and the module is gone. A report of
-// a node the build module no longer runs on is therefore not a builder (issue 1940: mesh-build-node unassigned from ace
-// on 2026-10-23 left ace.typescript at v26.12.0, and every Node fingerprint said "builders disagree").
-//
-// toolchainGate stands between the toolchains buckets and what takes their entries in (the indexer's PutToolchain, a
-// buildrun.ToolchainSet): an entry is passed on only while the controller's assignments (mesh-controller_assignments,
-// key <node>.<module>) hold an open assignment of its build module on its node, and only once it was written since that
-// assignment; it is passed on as deleted otherwise, said once, and passed on when its node writes it again. A report
-// written before the assignment is the one an earlier run of the module left (issue 1940, 2026-10-25 20:56: mesh-build-node
-// assigned to ace again brought ace.typescript v26.12.0 of 2026-10-23 back into the agreement, before the module ran
-// there, and the controller's take-in refused every module "builders disagree"). Until the assignments are settled (or where they cannot
-// be read) every entry is passed on, as before. Builders that run and report different versions still disagree: that
-// refusal is the guard of novox/hq ADR 0465, and it stays.
-type toolchainGate struct {
-	mu       sync.Mutex
-	modules  map[string]bool                                           // the build modules whose toolchains pass the gate
-	forward  func(module, key string, value []byte, deleted bool) bool // answers whether it changed what it holds
-	logf     func(format string, a ...any)
-	known    bool                         // the assignments are settled
-	standing map[string]time.Time         // <node>.<module> with an open assignment -> since when it stands
-	raw      map[string]map[string][]byte // module -> toolchains key -> value, as the bucket holds it
-	left     map[string]string            // <module>/<key> -> why it was said left out, so each reason is said once
-}
-
-func newToolchainGate(modules []string, forward func(module, key string, value []byte, deleted bool) bool, logf func(string, ...any)) *toolchainGate {
-	g := &toolchainGate{modules: map[string]bool{}, forward: forward, logf: logf, standing: map[string]time.Time{},
-		raw: map[string]map[string][]byte{}, left: map[string]string{}}
-	for _, m := range modules {
-		g.modules[m] = true
-	}
-	return g
-}
-
-// Toolchain takes one change of a build module's toolchains bucket in and answers whether what it passed on changed.
-func (g *toolchainGate) Toolchain(module, key string, value []byte, deleted bool) bool {
-	g.mu.Lock()
-	defer g.mu.Unlock()
-	if g.raw[module] == nil {
-		g.raw[module] = map[string][]byte{}
-	}
-	if deleted {
-		delete(g.raw[module], key)
-	} else {
-		g.raw[module][key] = value
-	}
-	return g.pass(module, key)
-}
-
-// Assignment takes one change of the controller's assignments in (at is when the bus wrote that revision) and answers
-// whether what it passed on changed.
-func (g *toolchainGate) Assignment(key string, value []byte, deleted bool, at time.Time) bool {
-	node, module, ok := strings.Cut(key, ".")
-	if !ok || !g.modules[module] {
-		return false
-	}
-	assigned, open := openAssignment(value)
-	open = open && !deleted
-	g.mu.Lock()
-	defer g.mu.Unlock()
-	was, stood := g.standing[key]
-	since := assigned
-	if since.IsZero() {
-		// A value with no time of its own (an assignment a module pulled in) stands since the revision that opened it.
-		since = at
-		if stood {
-			since = was
-		}
-	}
-	if open == stood && (!open || since.Equal(was)) {
-		return false
-	}
-	if open {
-		g.standing[key] = since
-	} else {
-		delete(g.standing, key)
-	}
-	if !g.known {
-		return false
-	}
-	changed := false
-	for _, k := range slices.Sorted(maps.Keys(g.raw[module])) {
-		if n, _, err := delivery.ParseToolchainKey(k); err == nil && n == node {
-			changed = g.pass(module, k) || changed
-		}
-	}
-	return changed
-}
-
-// Settled says the assignments are read: from now on only the reports of assigned nodes pass. It answers whether what it
-// passed on changed.
-func (g *toolchainGate) Settled() bool {
-	g.mu.Lock()
-	defer g.mu.Unlock()
-	g.known = true
-	changed := false
-	for _, module := range slices.Sorted(maps.Keys(g.raw)) {
-		for _, k := range slices.Sorted(maps.Keys(g.raw[module])) {
-			changed = g.pass(module, k) || changed
-		}
-	}
-	return changed
-}
-
-// pass hands one key on as it stands: its value when its node is assigned and wrote it since (or the assignments are not
-// known), deleted otherwise. The caller holds mu.
-func (g *toolchainGate) pass(module, key string) bool {
-	value, held := g.raw[module][key]
-	if !held {
-		return g.forward(module, key, nil, true)
-	}
-	node, _, err := delivery.ParseToolchainKey(key)
-	why := ""
-	if err == nil && g.known {
-		why = g.leftOut(module, node, value)
-	}
-	if why == "" {
-		delete(g.left, module+"/"+key)
-		return g.forward(module, key, value, false)
-	}
-	if g.left[module+"/"+key] != why {
-		g.left[module+"/"+key] = why
-		g.logf("%s.%s is left out of the agreed toolchain: %s (issue 1940)", delivery.ToolchainsBucket(module), key, why)
-	}
-	return g.forward(module, key, nil, true)
-}
-
-// leftOut is why a node's report is no builder's, or empty when it counts: its node has no open assignment of the module,
-// or the report was written before that assignment. A value that is no toolchain is passed on for its reader to refuse.
-// The caller holds mu.
-func (g *toolchainGate) leftOut(module, node string, value []byte) string {
-	since, open := g.standing[node+"."+module]
-	if !open {
-		return fmt.Sprintf("%s has no assignment on %s, so it is no builder", module, node)
-	}
-	tc, err := delivery.DecodeToolchain(value)
-	if err == nil && tc.At.Before(since) {
-		return fmt.Sprintf("it was written at %s, before %s's assignment on %s at %s: it counts once %s writes it again",
-			tc.At.UTC().Format(time.RFC3339), module, node, since.UTC().Format(time.RFC3339), node)
-	}
-	return ""
-}
-
-// openAssignment is whether a value of the controller's assignments holds an assignment that stands (one that has not
-// ended and has no state: a pending one is not on the machine yet; mesh-controller internal/chain Assignment), and when
-// it was assigned, zero where the value does not say.
-func openAssignment(value []byte) (time.Time, bool) {
-	var a struct {
-		Assigned time.Time `json:"assigned"`
-		Ended    time.Time `json:"ended"`
-		State    string    `json:"state"`
-	}
-	if json.Unmarshal(value, &a) != nil {
-		return time.Time{}, false
-	}
-	return a.Assigned, a.Ended.IsZero() && a.State == ""
-}
-
-// watchAssignments settles the controller's assignments into the gate, says them settled, and follows them; changed is
-// told whenever what the gate passes on changed. Where the bucket cannot be read (not there, or this module may not read
-// it) it says so and the gate passes every report on, as before; an error of the watch after that ends on the channel.
-func watchAssignments(ctx context.Context, js bucketOpener, gate *toolchainGate, changed func(context.Context), logger *log.Logger) (<-chan error, error) {
-	errs := make(chan error, 1)
-	kv, err := js.KeyValue(ctx, provider.AssignmentsBucket)
-	if err != nil {
-		// Not fatal: an indexer, builder or checker that stops for it stops every delivery (a grant comes with a delivery).
-		logger.Printf("the bucket %s cannot be read, so every node's toolchain report counts, an unassigned build node's too (issue 1940): %v", provider.AssignmentsBucket, err)
-		return errs, nil
-	}
-	each := func(e jetstream.KeyValueEntry) { gate.Assignment(e.Key(), e.Value(), !opOf(e), e.Created()) }
-	w, err := settle(ctx, kv, each)
-	if err != nil {
-		// Not fatal either (issue 1945): a watch the bus refuses is the same missing grant as a refused read.
-		logger.Printf("the bucket %s cannot be watched, so every node's toolchain report counts, an unassigned build node's too (issue 1940): %v", provider.AssignmentsBucket, err)
-		return errs, nil
-	}
-	if gate.Settled() {
-		changed(ctx)
-	}
-	go func() {
-		errs <- follow(ctx, w, func(e jetstream.KeyValueEntry) {
-			if gate.Assignment(e.Key(), e.Value(), !opOf(e), e.Created()) {
-				changed(ctx)
-			}
-		})
-	}()
-	return errs, nil
-}

modules/mesh-delivery-builder/cmd/mesh-delivery-builder/standing_test.go

@@ -1,228 +0,0 @@
-package main
-
-// The same in mesh-delivery-indexer, mesh-delivery-builder and mesh-delivery-checker, as standing.go is (issue 1940).
-
-import (
-	"bytes"
-	"context"
-	"errors"
-	"fmt"
-	"log"
-	"strings"
-	"testing"
-	"time"
-
-	"git.novox.be/novox/mesh-sdk/go/process"
-
-	"github.com/nats-io/nats.go/jetstream"
-
-	"git.novox.be/novox/mesh-sdk/go/delivery"
-	"git.novox.be/novox/mesh-sdk/go/delivery/buildrun"
-)
-
-func gateReport(t *testing.T, node, version string) (string, []byte) {
-	t.Helper()
-	key, err := delivery.ToolchainKey(node, "typescript")
-	if err != nil {
-		t.Fatal(err)
-	}
-	value, err := delivery.EncodeToolchain(delivery.Toolchain{Language: "typescript", Version: version, Recipe: "f59571cf4be75adf", At: time.Unix(0, 0).UTC()})
-	if err != nil {
-		t.Fatal(err)
-	}
-	return key, value
-}
-
-func agreedOf(set *buildrun.ToolchainSet) (string, string) {
-	tc, none := delivery.AgreedToolchain(set.Entries("typescript"))
-	return tc.Version, none
-}
-
-// The live case of issue 1940: mesh-build-node was unassigned from ace, whose report stayed at v26.12.0 while the
-// three nodes it runs on report v26.12.1. Without the assignments every report counts (and they disagree); with them
-// ace's is left out and the three agree; assigned to ace again, its report counts again and the guard refuses again.
-func TestAnUnassignedBuildNodesReportIsNoBuilder(t *testing.T) {
-	set := &buildrun.ToolchainSet{}
-	var said []string
-	gate := newToolchainGate([]string{buildrun.GoBuildModule, buildrun.NodeBuildModule}, set.Put, func(f string, a ...any) { said = append(said, f) })
-	for node, version := range map[string]string{"ace": "v26.12.0", "g14": "v26.12.1", "novox": "v26.12.1", "shanks": "v26.12.1"} {
-		key, value := gateReport(t, node, version)
-		gate.Toolchain(buildrun.NodeBuildModule, key, value, false)
-	}
-	if _, none := agreedOf(set); !strings.HasPrefix(none, "builders disagree") {
-		t.Fatalf("before the assignments are read every report counts, so they disagree; got %q", none)
-	}
-	for _, node := range []string{"g14", "novox", "shanks"} {
-		gate.Assignment(node+"."+buildrun.NodeBuildModule, []byte(`{"node":"`+node+`","module":"mesh-build-node"}`), false, time.Time{})
-	}
-	gate.Assignment("ace.mesh-build-node", []byte(`{"node":"ace","module":"mesh-build-node","ended":"2026-10-23T08:00:00Z"}`), false, time.Time{})
-	gate.Assignment("ace.mesh-build-go", []byte(`{"node":"ace","module":"mesh-build-go"}`), false, time.Time{}) // another module's: no matter
-	if !gate.Settled() {
-		t.Fatal("settling the assignments left ace's report out, so what was passed on changed")
-	}
-	if v, none := agreedOf(set); v != "v26.12.1" || none != "" {
-		t.Fatalf("the assigned nodes agree on v26.12.1; got %q, %q", v, none)
-	}
-	if len(said) != 1 {
-		t.Fatalf("ace's report is said left out once; said %v", said)
-	}
-	// ace reports again while unassigned (an old value seen again): still left out.
-	key, value := gateReport(t, "ace", "v26.12.0")
-	if gate.Toolchain(buildrun.NodeBuildModule, key, value, false) {
-		t.Fatal("an unassigned node's report changed what was passed on")
-	}
-	// Assigned to ace again: its report counts, and the builders really disagree: the guard stays.
-	if !gate.Assignment("ace.mesh-build-node", []byte(`{"node":"ace","module":"mesh-build-node"}`), false, time.Time{}) {
-		t.Fatal("assigning ace again passed nothing on")
-	}
-	if _, none := agreedOf(set); !strings.HasPrefix(none, "builders disagree: v26.12.0 recipe f59571cf4be75adf on ace") {
-		t.Fatalf("builders that run different versions still disagree; got %q", none)
-	}
-	// The assignment's key deleted, or a pending one written: no assignment stands, and ace's report goes again.
-	if !gate.Assignment("ace.mesh-build-node", []byte(`{"node":"ace","module":"mesh-build-node","state":"pending"}`), false, time.Time{}) {
-		t.Fatal("a pending assignment is no assignment on the machine")
-	}
-	if v, none := agreedOf(set); v != "v26.12.1" || none != "" {
-		t.Fatalf("got %q, %q", v, none)
-	}
-	gate.Assignment("ace.mesh-build-node", nil, true, time.Time{})
-	if v, _ := agreedOf(set); v != "v26.12.1" {
-		t.Fatalf("got %q", v)
-	}
-	// A report deleted from the bucket goes whether its node is assigned or not.
-	key, _ = gateReport(t, "g14", "v26.12.1")
-	if !gate.Toolchain(buildrun.NodeBuildModule, key, nil, true) {
-		t.Fatal("deleting g14's report passed nothing on")
-	}
-	if n := len(set.Entries("typescript")); n != 2 {
-		t.Fatalf("novox and shanks are left; got %d entries", n)
-	}
-
-	// 1945 (a part exits at start for a bucket it works without): a bus that refuses the assignments' watch, or every
-	// toolchains bucket, leaves the watches unstarted and the part running, said; a refused bucket it cannot work without
-	// is an error naming the bucket and its grant.
-	var logs bytes.Buffer
-	logger := log.New(&logs, "", 0)
-	refused := refusingBus{err: errors.New("nats: permissions violation for publish to $JS.API.CONSUMER.CREATE.KV_mesh-controller_assignments")}
-	if _, err := watchAssignments(context.Background(), refused, newToolchainGate(nil, set.Put, t.Logf), func(context.Context) {}, logger); err != nil {
-		t.Errorf("a refused watch of the assignments stopped the start: %v", err)
-	}
-	if err := newToolchainWatch(context.Background(), refusingBus{refuseOpen: true, err: refused.err}, set, func(context.Context) {}, logger).start(); err != nil {
-		t.Errorf("a refused toolchains bucket stopped the start: %v", err)
-	}
-	if !strings.Contains(logs.String(), "cannot be watched") || !strings.Contains(logs.String(), "cannot be read") {
-		t.Errorf("the refusals were not said: %q", logs.String())
-	}
-	if _, err := process.EssentialBucket(context.Background(), refusingBus{refuseOpen: true, err: refused.err}, "builder", "mesh-delivery-indexer_modules", "work"); err == nil ||
-		!strings.Contains(err.Error(), "grant of mesh-delivery-indexer_modules") {
-		t.Errorf("a refused bucket the part needs: %v, want an error naming its grant", err)
-	}
-	// The gate's source (the previews' trunk heads): refused at start, the builder goes on, and a candidate asking a trunk
-	// head is told why and opens it again then.
-	src := &trunkSource{ctx: context.Background(), js: refusingBus{refuseOpen: true, err: refused.err}, heads: &sourceHeads{}, errs: make(chan error, 1), logf: logger.Printf}
-	src.start()
-	if _, err := src.head(context.Background(), 7, "novox/mesh-catalog"); err == nil || !strings.Contains(err.Error(), delivery.SourceBucket) {
-		t.Errorf("a trunk head with the source refused: %v, want why", err)
-	}
-	if src.opened {
-		t.Error("a refused source counts as opened, so it is never opened again")
-	}
-}
-
-// refusingBus is a bus that refuses: every open (refuseOpen), or every watch of a bucket it opens, with err.
-type refusingBus struct {
-	refuseOpen bool
-	err        error
-}
-
-func (r refusingBus) KeyValue(context.Context, string) (jetstream.KeyValue, error) {
-	if r.refuseOpen {
-		return nil, r.err
-	}
-	return refusedWatch{err: r.err}, nil
-}
-
-type refusedWatch struct {
-	jetstream.KeyValue
-	err error
-}
-
-func (r refusedWatch) WatchAll(context.Context, ...jetstream.WatchOpt) (jetstream.KeyWatcher, error) {
-	return nil, r.err
-}
-func (r refusedWatch) Watch(context.Context, string, ...jetstream.WatchOpt) (jetstream.KeyWatcher, error) {
-	return nil, r.err
-}
-
-// A build node's report counts from the first one it writes since its assignment: a newly assigned node that has not
-// reported changes nothing, and the report an earlier run left on the bus (issue 1940, 2026-10-25 20:56: ace.typescript
-// v26.12.0 of 2026-10-23 06:29, mesh-build-node assigned to ace again at 20:56:45) is left out, said once, until the node
-// writes it again. An assignment whose value names no time stands since the revision that opened it.
-func TestANewlyAssignedNodeCountsFromItsReport(t *testing.T) {
-	left := time.Date(2026, 10, 23, 6, 29, 18, 0, time.UTC)      // ace's report from its earlier run
-	assigned := time.Date(2026, 10, 25, 19, 56, 45, 0, time.UTC) // mesh-build-node assigned to ace again
-	report := func(t *testing.T, node, version string, at time.Time) (string, []byte) {
-		key, _ := gateReport(t, node, version)
-		value, err := delivery.EncodeToolchain(delivery.Toolchain{Language: "typescript", Version: version, Recipe: "f59571cf4be75adf", At: at})
-		if err != nil {
-			t.Fatal(err)
-		}
-		return key, value
-	}
-	for _, c := range []struct {
-		name       string
-		assignment string    // ace's assignment value
-		revision   time.Time // when the bus wrote it
-		at         time.Time // when ace wrote its report
-		counts     bool
-	}{
-		{"no report yet, then one", `{}`, time.Time{}, time.Now(), true},
-		{"a report left before the assignment", `{"node":"ace","module":"mesh-build-node","assigned":"2026-10-25T19:56:45Z"}`, assigned, left, false},
-		{"a report left before a value with no time", `{"node":"ace","module":"mesh-build-node"}`, assigned, left, false},
-		{"a report written since the assignment", `{"node":"ace","module":"mesh-build-node","assigned":"2026-10-25T19:56:45Z"}`, assigned, assigned.Add(30 * time.Second), true},
-	} {
-		t.Run(c.name, func(t *testing.T) {
-			set := &buildrun.ToolchainSet{}
-			var said []string
-			gate := newToolchainGate([]string{buildrun.NodeBuildModule}, set.Put, func(f string, a ...any) { said = append(said, fmt.Sprintf(f, a...)) })
-			for _, node := range []string{"g14", "novox", "shanks"} {
-				gate.Assignment(node+".mesh-build-node", []byte(`{}`), false, time.Time{})
-				key, value := gateReport(t, node, "v26.12.1")
-				gate.Toolchain(buildrun.NodeBuildModule, key, value, false)
-			}
-			gate.Settled()
-			if gate.Assignment("ace.mesh-build-node", []byte(c.assignment), false, c.revision) {
-				t.Fatal("an assignment with no report passed something on")
-			}
-			key, value := report(t, "ace", "v26.12.0", c.at)
-			if got := gate.Toolchain(buildrun.NodeBuildModule, key, value, false); got != c.counts {
-				t.Fatalf("ace's report passed on: %v, want %v", got, c.counts)
-			}
-			// A rewrite of the assignment that does not move it changes nothing, and nothing is said again.
-			if gate.Assignment("ace.mesh-build-node", []byte(c.assignment), false, c.revision.Add(time.Minute)) {
-				t.Fatal("the same assignment written again changed what was passed on")
-			}
-			v, none := agreedOf(set)
-			if c.counts {
-				if !strings.HasPrefix(none, "builders disagree: v26.12.0 recipe f59571cf4be75adf on ace") {
-					t.Fatalf("ace's own report counts and disagrees; got %q, %q", v, none)
-				}
-				return
-			}
-			if v != "v26.12.1" || none != "" {
-				t.Fatalf("ace's left report is no builder's, so g14, novox and shanks agree; got %q, %q", v, none)
-			}
-			if len(said) != 1 || !strings.Contains(said[0], "before mesh-build-node's assignment on ace at 2026-10-25T19:56:45Z") {
-				t.Fatalf("said %q, want once why ace's report is left out", said)
-			}
-			// ace writes its report again since it was assigned: it counts.
-			key, value = report(t, "ace", "v26.12.1", assigned.Add(time.Minute))
-			if !gate.Toolchain(buildrun.NodeBuildModule, key, value, false) {
-				t.Fatal("ace's new report was not passed on")
-			}
-			if n := len(set.Entries("typescript")); n != 4 {
-				t.Fatalf("four builders report; got %d", n)
-			}
-		})
-	}
-}

modules/mesh-delivery-builder/go.mod

@@ -3,7 +3,7 @@ module mesh-delivery-builder
 go 1.26.0
 
 require (
-	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261025211220-e0d1de047585
+	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261028205404-8eafc0c5ce3c
 	github.com/nats-io/nats-server/v2 v2.11.17
 	github.com/nats-io/nats.go v1.54.0
 )

modules/mesh-delivery-builder/go.sum

@@ -1,7 +1,5 @@
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261024020722-34f210e5eba1 h1:fzOkrz9CSp3mEjeV7NfZx8yoivI1sD1AOtIPtyyF8RI=
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261024020722-34f210e5eba1/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261025211220-e0d1de047585 h1:7QoFH5qjXRpx5M4uPdYsVJ5qKl2082gq8n0lFxhoNIg=
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261025211220-e0d1de047585/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261028205404-8eafc0c5ce3c h1:hcqOCd5q3M0ZiEzB6MhwxT/AOKkm9gaskKqPcpkAAg8=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261028205404-8eafc0c5ce3c/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op h1:Z/MZK75wC/NSrkgqeNIa7jexam9uWzhLmFTSCPI/kn0=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op/go.mod h1:FQyySiasQQM8735Ddel3MRojmy4dA1IqCeyJ5jmPMbI=
 github.com/google/go-tpm v0.9.8 h1:slArAR9Ft+1ybZu0lBwpSmpwhRXaa85hWtMinMyRAWo=

modules/mesh-delivery-builder/internal/build/askagain.go

@@ -12,6 +12,7 @@ import (
 
 	"git.novox.be/novox/mesh-sdk/go/buildstep"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
+	"git.novox.be/novox/mesh-sdk/go/delivery/buildrun"
 )
 
 // **An ask that can no longer be answered is asked again** (novox/hq issue 1945). A build seat's stream gives an ask up
@@ -20,7 +21,8 @@ import (
 // restart take over the same id and wait again. The builder notices it at the check bound (CheckAfter, the step bound),
 // a context's bound and no timer of its own: it asks Gone, which reads the bus, and asks such an ask again under a new
 // id, written into the key, said in its log and as the event build.asked-again, at most Askings times; then the key is
-// failed with why. A person asks the same by hand with the tool builder_ask_again (AskAgain).
+// failed with why. An ask DEAD_LETTERS says the seat gave up (buildrun.LostAskWaiter, issue 734) is asked again at once.
+// A person asks the same by hand with the tool builder_ask_again (AskAgain).
 
 // DefaultAskings is how many times a build module's part of a build is asked, the first included, when Builder.Askings is 0.
 const DefaultAskings = 3
@@ -315,6 +317,11 @@ func (b *Builder) waitOnce(ctx context.Context, ask delivery.StepAsk, again <-ch
 		defer stop()
 	}
 	step, err := b.Asks.Wait(wait, ask)
+	if err == nil && buildrun.IsLost(step) {
+		// The build seat gave the ask up (issue 734): it can no longer be answered, so it is asked again now, with the
+		// words of why, not at the check bound.
+		return step, step.Reason, errAgain
+	}
 	if err == nil || ctx.Err() != nil {
 		return step, "", err
 	}

modules/mesh-delivery-builder/internal/build/buildagain.go

@@ -0,0 +1,183 @@
+package build
+
+import (
+	"context"
+	"fmt"
+	"maps"
+	"strings"
+	"time"
+
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+	"git.novox.be/novox/mesh-sdk/go/delivery/buildrun"
+)
+
+// **A failed key is built again by hand** (novox/hq issue 1126 note 72; ADR 0429 clause 18: "a fingerprint is built again
+// only when its build key failed, as a new revision of the same key"). The builder does it by itself whenever it looks at a
+// module again (a modules value, a change of the toolchains, artifacts-gone, a moved trunk): Claimer.Claim writes a failed
+// key building as a new revision and the build asks the build seats. Nothing looks at an unchanged module on its own, so a key
+// that failed (a node refused the build, a toolchain was missing) stayed failed until the module changed. The tool
+// builder_build_again (BuildAgain) makes the builder look at one module now, which does exactly that and no more: it keeps
+// the claim's rules, so a key failed for a reason the builder never retries on the same fingerprint stays refused.
+
+// BuildAgainResult is the builder's answer to a request to build a key again.
+type BuildAgainResult struct {
+	// Refused is why nothing was done, "" when the key was written building as a new revision.
+	Refused string
+	// Revision is the revision the claim wrote; Asks are the ask ids put by language, as far as they were put within the bound.
+	Revision uint64
+	Asks     map[string]string
+	// Pending says the builder had not claimed the key, or not put every ask, when it answered: not a refusal.
+	Pending string
+	// Failed is the error of the key when the build ended failed before its asks were put (a plan that cannot be read, a
+	// toolchain not agreed): the new revision was written, and nothing was asked.
+	Failed string
+}
+
+// handWatch follows one request to build a key again until its asks are put.
+type handWatch struct {
+	rev   uint64
+	lanes int
+	asks  map[string]string
+	done  chan struct{}
+	shut  bool
+	// ended is set when the look ended before the asks were all put.
+	ended bool
+}
+
+// settle closes done once the claim is written and every lane has put its ask. Call with b.mu held.
+func (w *handWatch) settle() {
+	if !w.shut && w.rev > 0 && w.lanes >= 0 && len(w.asks) >= w.lanes {
+		w.shut = true
+		close(w.done)
+	}
+}
+
+func (b *Builder) hand(key string, f func(w *handWatch)) {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	if w := b.hands[key]; w != nil {
+		f(w)
+	}
+}
+
+func (b *Builder) handClaimed(key string, rev uint64) {
+	b.hand(key, func(w *handWatch) { w.rev = rev; w.settle() })
+}
+
+func (b *Builder) handLanes(key string, n int) {
+	b.hand(key, func(w *handWatch) { w.lanes = n; w.settle() })
+}
+
+func (b *Builder) handAsk(key, language, id string) {
+	b.hand(key, func(w *handWatch) { w.asks[language] = id; w.settle() })
+}
+
+// handEnded ends the watch of a request whose look ended: it wrote no claim, or the build ended.
+func (b *Builder) handEnded(key string) {
+	b.hand(key, func(w *handWatch) {
+		if !w.shut {
+			w.shut, w.ended = true, true
+			close(w.done)
+		}
+	})
+}
+
+// BuildAgain builds the failed key of module at fp again, as the builder does by itself: the key is written building as a
+// new revision and the build module asks are put on the build seats. It answers once the asks are put, or at bound. A key
+// that is not failed is refused with why: done (nothing to do) or waiting (builder_ask_again asks its waiting asks again).
+// ctx is the builder's own context: the build it starts lives on it.
+func (b *Builder) BuildAgain(ctx context.Context, module, fp, why, by string, bound time.Duration) BuildAgainResult {
+	b.init()
+	key, err := delivery.BuilderBuildKey(module, fp)
+	if err != nil {
+		return BuildAgainResult{Refused: err.Error()}
+	}
+	value, _, found, err := b.Claimer.Store.Get(ctx, key)
+	if err != nil {
+		return BuildAgainResult{Refused: fmt.Sprintf("%s cannot be read: %v", key, err)}
+	}
+	if !found {
+		return BuildAgainResult{Refused: fmt.Sprintf("%s has no build key: nothing failed. The builder builds a fingerprint by itself once the indexer writes it to its module", key)}
+	}
+	cur, err := delivery.DecodeBuilderBuild(value)
+	if err != nil {
+		return BuildAgainResult{Refused: fmt.Sprintf("%s holds what is not a build: %v", key, err)}
+	}
+	switch {
+	case cur.State == delivery.BuildDone:
+		return BuildAgainResult{Refused: fmt.Sprintf("%s is done: nothing to do", key)}
+	case cur.State == delivery.BuildBuilding || cur.State == delivery.BuildQueued:
+		return BuildAgainResult{Refused: fmt.Sprintf("%s is waiting (%s: %s): %s asks its waiting asks again", key, cur.State, cur.Step, AskAgainTool)}
+	case cur.State != delivery.BuildFailed:
+		return BuildAgainResult{Refused: fmt.Sprintf("%s is %q, not failed", key, cur.State)}
+	case delivery.FailedUntilChanged(cur.Error) || strings.HasPrefix(cur.Error, buildrun.DigestsDifferPrefix):
+		return BuildAgainResult{Refused: fmt.Sprintf("%s failed for a reason the builder does not retry on the same fingerprint, it waits for another fingerprint: %s", key, cur.Error)}
+	}
+	// One critical section: the key is refused when it is looked at or asked already, the module still has the fingerprint,
+	// and the watch and the look are registered before anything else can take the key.
+	w := &handWatch{lanes: -1, asks: map[string]string{}, done: make(chan struct{})}
+	b.mu.Lock()
+	m, known := b.known[module]
+	switch {
+	case !known || m.FP2 != fp:
+		b.mu.Unlock()
+		return BuildAgainResult{Refused: fmt.Sprintf("module %s does not have the fingerprint %s now (a newer one superseded it, or its modules value is not read yet): the builder builds the module's current fingerprint", module, fp)}
+	case m.Manifest == "":
+		b.mu.Unlock()
+		return BuildAgainResult{Refused: fmt.Sprintf("module %s names no manifest at %s yet, so the builder looks at nothing", module, fp)}
+	case b.inflight[key] || b.hands[key] != nil:
+		b.mu.Unlock()
+		return BuildAgainResult{Refused: fmt.Sprintf("%s is being looked at by this builder now (or asked again by hand): wait for it to end", key)}
+	}
+	b.hands[key] = w
+	b.inflight[key] = true
+	b.mu.Unlock()
+	defer func() {
+		b.mu.Lock()
+		if b.hands[key] == w {
+			delete(b.hands, key)
+		}
+		b.mu.Unlock()
+	}()
+	b.logf("%s: failed (%s); built again by hand, asked by %s: %s", key, cur.Error, by, why)
+	b.startOnce(ctx, key, module, m)
+	wait, stop := context.WithTimeout(ctx, bound) // a context's bound for a person's answer (ADR 0437 §8)
+	defer stop()
+	select {
+	case <-w.done:
+	case <-wait.Done():
+	}
+	b.mu.Lock()
+	res := BuildAgainResult{Revision: w.rev, Asks: maps.Clone(w.asks)}
+	ended, shut, lanes := w.ended, w.shut, w.lanes
+	b.mu.Unlock()
+	switch {
+	case res.Revision == 0 && shut:
+		res.Refused = fmt.Sprintf("the builder looked at %s and wrote nothing (a toolchain moved, the claim was lost or could not be written): its log says why", key)
+	case res.Revision == 0:
+		res.Pending = fmt.Sprintf("the builder has not claimed %s within %s: it waits behind other builds; builder_stuck shows where it stands", key, bound)
+	case ended && len(res.Asks) < max(lanes, 0)+boolInt(lanes < 0):
+		// The look ended before every ask was put: say how the key stands, not that it was asked.
+		if v, _, found, err := b.Claimer.Store.Get(ctx, key); err == nil && found {
+			if cur, err := delivery.DecodeBuilderBuild(v); err == nil {
+				switch cur.State {
+				case delivery.BuildFailed:
+					res.Failed = cur.Error
+				case delivery.BuildDone:
+				default:
+					res.Pending = fmt.Sprintf("the look ended with the key %s (%s) before every ask was put: its log says why", cur.State, cur.Step)
+				}
+			}
+		}
+	case !shut:
+		res.Pending = fmt.Sprintf("the key is building at revision %d, and not every ask was put within %s; builder_stuck shows the asks", res.Revision, bound)
+	}
+	return res
+}
+
+func boolInt(b bool) int {
+	if b {
+		return 1
+	}
+	return 0
+}

modules/mesh-delivery-builder/internal/build/run.go

@@ -89,6 +89,8 @@ type Builder struct {
 	held map[string]bool
 	// waiting are the lanes that wait for an ask's step, by build key and language: AskAgain asks through them.
 	waiting map[string]map[string]chan string
+	// hands are the requests to build a key again by hand that wait for the claim and its asks (BuildAgain), by build key.
+	hands map[string]*handWatch
 }
 
 type planned struct {
@@ -106,6 +108,7 @@ func (b *Builder) init() {
 		b.cands, b.via, b.trunkFP = map[string]delivery.Candidate{}, map[string]via{}, map[string]bool{}
 		b.known, b.inflight, b.again, b.plans, b.tried = map[string]delivery.Module{}, map[string]bool{}, map[string]delivery.Module{}, map[string]planned{}, map[string]bool{}
 		b.published, b.held, b.waiting = map[string]bool{}, map[string]bool{}, map[string]map[string]chan string{}
+		b.hands = map[string]*handWatch{}
 	})
 }
 
@@ -372,9 +375,35 @@ func (b *Builder) consider(ctx context.Context, module string, m delivery.Module
 	}()
 }
 
+// startOnce looks at the module for a key the caller has set inflight already (BuildAgain): the by-hand look runs once, and
+// a look the builder queued for the key meanwhile (again) still runs after it, as consider's loop does.
+func (b *Builder) startOnce(ctx context.Context, key, module string, m delivery.Module) {
+	b.wg.Add(1)
+	go func() {
+		defer b.wg.Done()
+		b.sem <- struct{}{}
+		defer func() { <-b.sem }()
+		for {
+			b.try(ctx, module, m)
+			b.mu.Lock()
+			next, more := b.again[key]
+			delete(b.again, key)
+			if !more || ctx.Err() != nil {
+				delete(b.inflight, key)
+				b.mu.Unlock()
+				return
+			}
+			b.mu.Unlock()
+			m = next // a look the builder queued meanwhile is not lost (consider's rule); it is not a second by-hand build
+		}
+	}()
+}
+
 // try claims the fingerprint and builds it, writing the key done or failed. A build that ends because ctx did is left
 // building by this builder: it takes it again when it starts (ADR 0478 clause 5).
 func (b *Builder) try(ctx context.Context, module string, m delivery.Module) {
+	key, _ := delivery.BuilderBuildKey(module, m.FP2)
+	defer b.handEnded(key)
 	plan, planErr, read := b.planOf(ctx, m.Manifest)
 	nothing := read && planErr == nil && len(plan.Tasks) == 0
 	if planErr == nil && !nothing {
@@ -385,7 +414,6 @@ func (b *Builder) try(ctx context.Context, module string, m delivery.Module) {
 			return
 		}
 	}
-	key, _ := delivery.BuilderBuildKey(module, m.FP2)
 	b.mu.Lock()
 	trunk := b.trunkFP[key]
 	first := !b.tried[key]
@@ -400,6 +428,7 @@ func (b *Builder) try(ctx context.Context, module string, m delivery.Module) {
 	if cl == nil {
 		return
 	}
+	b.handClaimed(key, cl.Rev)
 	if cl.Unasked != nil {
 		b.logf("%v", cl.Unasked)
 	}
@@ -535,6 +564,9 @@ func (b *Builder) build(ctx context.Context, module string, m delivery.Module, p
 		// One ask builds each fingerprint's part of a build module, on whichever node pulls it (ADR 0525 §3).
 		lanes = append(lanes, &lane{module: bm, tasks: tasks, toolchain: toolchain, digests: map[string]string{}, references: map[string]string{}})
 	}
+	if key, err := delivery.BuilderBuildKey(module, m.FP2); err == nil {
+		b.handLanes(key, len(lanes))
+	}
 	var wg sync.WaitGroup
 	for _, l := range lanes {
 		wg.Add(1)
@@ -717,7 +749,11 @@ func (n *askNotes) note(ctx context.Context, language, id, step string) error {
 		v.Asks = map[string]string{}
 	}
 	v.Asks[language] = id
-	return n.b.Claimer.Finish(ctx, n.cl, v)
+	if err := n.b.Claimer.Finish(ctx, n.cl, v); err != nil {
+		return err
+	}
+	n.b.handAsk(n.cl.Key, language, id)
+	return nil
 }
 
 // runLane puts the lane's part of the build as one ask on its build seat's stream (the delivery stream for a trunk key, the

modules/mesh-delivery-builder/internal/build/run_test.go

@@ -690,17 +690,130 @@ func TestABuildAskWaitingInItsStreamIsNotBounded(t *testing.T) {
 		step   string
 		byHand bool
 		always bool // Gone says every ask cannot be answered, not only the first
+		dead   bool // DEAD_LETTERS keeps the first ask: the seat gave it up (issue 734)
+		deaf   bool // the ask's own watch hears nothing though its step ends (the lost check of 2026-10-28)
 		puts   int
 		done   bool
 		asking int // the asking the event says, 0 when none is said
+		// again, when set, is a request to build the key again by hand (BuildAgain, issue 1126 note 72) of the key as
+		// it stands (key, absent when nil), the module known at known's fingerprint ("" for the rig's): refuse is a part of why it
+		// is refused, "" when it is built again as a new revision and its ask id answered.
+		again  bool
+		key    *delivery.BuilderBuild
+		known  string
+		refuse string
+		// edit changes the module the builder has read, busy marks the key looked at (1) or asked by hand (2), failed is a part of
+		// the error the key then holds when its build ends before its asks are put.
+		edit   func(m *delivery.Module)
+		busy   int
+		failed string
+		// during is a look of the builder's own at the module while the by-hand build runs: it still runs afterwards.
+		during bool
 	}{
+		{name: "build again: a look the builder queued during the by-hand build still runs afterwards", again: true, during: true,
+			key: &delivery.BuilderBuild{State: delivery.BuildFailed, Error: "ace: no tun"}},
+		{name: "build again: a key looked at by the builder now is refused, not built twice", again: true, refuse: "is being looked at", busy: 1,
+			key: &delivery.BuilderBuild{State: delivery.BuildFailed, Error: "ace: no tun"}},
+		{name: "build again: a key already asked by hand is refused, its watch kept", again: true, refuse: "is being looked at", busy: 2,
+			key: &delivery.BuilderBuild{State: delivery.BuildFailed, Error: "ace: no tun"}},
+		{name: "build again: a module with no manifest is refused", again: true, refuse: "names no manifest", edit: func(m *delivery.Module) { m.Manifest = "" },
+			key: &delivery.BuilderBuild{State: delivery.BuildFailed, Error: "ace: no tun"}},
+		{name: "build again: a toolchain that moved writes nothing and is said at once", again: true, refuse: "wrote nothing",
+			edit: func(m *delivery.Module) {
+				m.Toolchains = map[string]delivery.ToolchainUsed{"go": {Version: "go1.0", Recipe: "1"}}
+			},
+			key: &delivery.BuilderBuild{State: delivery.BuildFailed, Error: "ace: no tun"}},
+		{name: "build again: a build that fails before its asks says the key failed, not that it was asked", again: true, failed: "cannot be read",
+			edit: func(m *delivery.Module) { m.Manifest = mdigest('b') },
+			key:  &delivery.BuilderBuild{State: delivery.BuildFailed, Error: "ace: no tun"}},
+		{name: "build again: a failed key is written building as a new revision and asks the seat", again: true,
+			key: &delivery.BuilderBuild{State: delivery.BuildFailed, Error: "ace: the step failed: no tun"}},
+		{name: "build again: a done key is refused, nothing to do", again: true, refuse: "is done: nothing to do",
+			key: &delivery.BuilderBuild{State: delivery.BuildDone, Step: "built"}},
+		{name: "build again: a building key is refused, builder_ask_again is for it", again: true, refuse: "is waiting",
+			key: &delivery.BuilderBuild{State: delivery.BuildBuilding, By: "novox.builder", Step: "asked mesh-build-go", Asks: map[string]string{delivery.AskGo: "mvl0frv18d1960"}}},
+		{name: "build again: a key failed for a pin missing is refused, it waits for another fingerprint", again: true, refuse: "does not retry",
+			key: &delivery.BuilderBuild{State: delivery.BuildFailed, Error: delivery.NotPinned + "web"}},
+		{name: "build again: a key with no build is refused", again: true, refuse: "has no build key"},
+		{name: "build again: a fingerprint its module no longer has is refused", again: true, refuse: "does not have the fingerprint", known: "src2:" + strings.Repeat("9", 64),
+			key: &delivery.BuilderBuild{State: delivery.BuildFailed, Error: "ace: no tun"}},
 		{name: "given up by its stream: asked again under a new id and done from it", puts: 2, done: true, asking: 2},
 		{name: "asked again by hand: the same, with no check bound", byHand: true, puts: 2, done: true, asking: 2},
+		{name: "given up into DEAD_LETTERS: its wait ends failed with the words and it is asked again at once", dead: true, puts: 2, done: true, asking: 2},
+		{name: "its step ended while its watch was deaf: read at its build module's next step end, done with no new ask", deaf: true, puts: 1, done: true},
 		{name: "never answerable: failed after its askings", askings: 2, always: true, puts: 2},
 		{name: "taken over at its last asking: failed, not asked again", askings: 3, always: true, step: "asked mesh-build-go again (asking 3): x", puts: 0},
 	} {
 		t.Run(c.name, func(t *testing.T) { // 1945
 			r := newRig(t, goBundle)
+			if c.again {
+				var rev uint64
+				if c.key != nil {
+					c.key.Manifest = manifestD
+					rev = putBuild(t, r.st, r.key, *c.key)
+				}
+				m, err := delivery.DecodeModule(moduleValue(t, "modules/m"))
+				if err != nil {
+					t.Fatal(err)
+				}
+				if c.known != "" {
+					m.FP2 = c.known
+				}
+				if c.edit != nil {
+					c.edit(&m)
+				}
+				r.b.init()
+				var stored atomic.Int64
+				if c.during {
+					r.asks.Answer = nil
+					r.b.Stored = func(context.Context, []string) ([]string, error) { stored.Add(1); return nil, nil }
+				}
+				switch c.busy {
+				case 1:
+					r.b.inflight[r.key] = true
+				case 2:
+					r.b.hands[r.key] = &handWatch{}
+				}
+				r.b.known["m"] = m // the builder has read the modules value, and looks at nothing until asked
+				log := &logged{}
+				r.b.Logf = log.logf
+				res := r.b.BuildAgain(context.Background(), "m", fp1, "no tun on ace", "shanks.lead", 2*time.Second)
+				if c.during {
+					// The trunk's modules value arrives while the by-hand build waits for its ask: it is queued, and run after it.
+					r.b.Module(context.Background(), "m", moduleValue(t, "modules/m"))
+					r.asks.End(r.answer(waitForAsks(t, r, 1)[0]))
+					r.b.Wait()
+					if v := valueOf(t, r.st, r.key); v.State != delivery.BuildDone || res.Revision <= rev || stored.Load() != 1 {
+						t.Fatalf("key %+v, answer %+v, %d asks of the store; want built from the new revision and the queued look run once after it", v, res, stored.Load())
+					}
+					return
+				}
+				r.b.Wait()
+				after := r.st.revs[r.key]
+				if c.refuse != "" {
+					if !strings.Contains(res.Refused, c.refuse) || res.Revision != 0 || len(r.asks.Asks()) != 0 || after != rev {
+						t.Fatalf("refused %q (revision %d, %d asks, key at revision %d was %d); want refused with %q and nothing written or asked", res.Refused, res.Revision, len(r.asks.Asks()), after, rev, c.refuse)
+					}
+					return
+				}
+				if c.failed != "" {
+					if !strings.Contains(res.Failed, c.failed) || res.Revision <= rev || len(res.Asks) != 0 || len(r.asks.Asks()) != 0 {
+						t.Fatalf("answer %+v after %d asks; want a new revision (was %d), no ask and the key's failure %q", res, len(r.asks.Asks()), rev, c.failed)
+					}
+					return
+				}
+				asks := r.asks.Asks()
+				if res.Refused != "" || res.Pending != "" || res.Revision <= rev || len(asks) != 1 || res.Asks[delivery.AskGo] != asks[0].ID {
+					t.Fatalf("answer %+v after %d asks; want the new revision (was %d) and the ask id of the one ask", res, len(asks), rev)
+				}
+				if v := valueOf(t, r.st, r.key); v.State != delivery.BuildDone || after <= res.Revision {
+					t.Errorf("the key = %+v at revision %d; want built from the new revision %d", v, after, res.Revision)
+				}
+				if !log.has(r.key, "built again by hand", "no tun on ace", "shanks.lead") {
+					t.Errorf("the why is not logged: %v", log.lines)
+				}
+				return
+			}
 			r.asks.Answer = nil
 			r.b.Askings = c.askings
 			var said []AskedAgain
@@ -714,7 +827,16 @@ func TestABuildAskWaitingInItsStreamIsNotBounded(t *testing.T) {
 				r.st.vals[r.key] = data
 			}
 			gone := &goneAsks{}
-			if !c.byHand {
+			dead := &buildrun.DeadLetters{}
+			if c.dead {
+				r.b.Asks = buildrun.Asker{Publisher: r.asks, Waiter: buildrun.LostAskWaiter{Inner: r.asks, Dead: dead}, Bound: 2 * time.Second}
+			}
+			var heard *buildrun.HeardEnds
+			if c.deaf {
+				heard = &buildrun.HeardEnds{Inner: silentWatch{}, Read: r.asks}
+				r.b.Asks = buildrun.Asker{Publisher: r.asks, Waiter: heard, Bound: 2 * time.Second}
+			}
+			if !c.byHand && !c.dead && !c.deaf {
 				gone.why = func(a delivery.StepAsk) string {
 					if c.always || a.ID == first || first == "" {
 						return "it waits first in line while a node took a later ask"
@@ -724,6 +846,10 @@ func TestABuildAskWaitingInItsStreamIsNotBounded(t *testing.T) {
 				r.b.Gone, r.b.CheckAfter = gone, 5*time.Millisecond
 			}
 			r.b.Module(context.Background(), "m", moduleValue(t, "modules/m"))
+			if c.dead {
+				dead.Heard(buildrun.GivenUp{AskID: waitForAsks(t, r, 1)[0].ID, Stream: "SEAT_NODE_BUILD_GO", Deliveries: 5,
+					At: time.Date(2026, 10, 26, 12, 26, 40, 0, time.UTC)})
+			}
 			if c.byHand {
 				waitForAsks(t, r, 1)
 				for deadline := time.Now().Add(2 * time.Second); len(r.b.AskAgain(r.key, "stuck since 19:06")) == 0; time.Sleep(time.Millisecond) {
@@ -732,7 +858,16 @@ func TestABuildAskWaitingInItsStreamIsNotBounded(t *testing.T) {
 					}
 				}
 			}
-			if c.done {
+			if c.deaf {
+				r.asks.End(r.answer(waitForAsks(t, r, 1)[0]))
+				for deadline := time.Now().Add(2 * time.Second); heard.Waiting() == 0; time.Sleep(time.Millisecond) {
+					if time.Now().After(deadline) {
+						t.Fatal("no ask is waited on")
+					}
+				}
+				heard.Nudge(buildrun.GoBuildModule) // a step of mesh-build-go ended
+			}
+			if c.done && !c.deaf {
 				asks := waitForAsks(t, r, c.puts)
 				if first == "" && !c.byHand {
 					first = asks[0].ID
@@ -757,13 +892,16 @@ func TestABuildAskWaitingInItsStreamIsNotBounded(t *testing.T) {
 			mu.Lock()
 			defer mu.Unlock()
 			// Note 62: the old message of an ask asked again because its stream gave it up is dropped from the stream.
-			if gone.mu.Lock(); c.done && !c.byHand && (len(gone.dropped) != 1 || gone.dropped[0] != first) {
+			if gone.mu.Lock(); c.done && !c.byHand && !c.dead && !c.deaf && (len(gone.dropped) != 1 || gone.dropped[0] != first) {
 				t.Errorf("dropped %v from the stream, want the old ask %s", gone.dropped, first)
 			}
 			gone.mu.Unlock()
 			if c.asking > 0 && (len(said) != 1 || said[0].Asking != c.asking || said[0].New == said[0].Old || said[0].Key != r.key || said[0].Why == "") {
 				t.Errorf("said %+v, want once at asking %d", said, c.asking)
 			}
+			if c.dead && (len(said) != 1 || !strings.Contains(said[0].Why, buildrun.LostWords+" after 5 deliveries at 2026-10-26T12:26:40Z")) {
+				t.Errorf("said %+v, want the ask asked again saying the seat gave it up", said)
+			}
 		})
 	}
 	t.Run("what the bus says of an ask", func(t *testing.T) { // 1945
@@ -836,12 +974,17 @@ func TestABuildAskWaitingInItsStreamIsNotBounded(t *testing.T) {
 		running, _ := json.Marshal(delivery.Step{V: delivery.Version, ID: "mvo53jcm70b5f8", Tool: "delivery ask", Node: "g14", State: delivery.StepRunning, Started: at})
 		_, reask, _ := NewReAsk("m", fp1, "stuck", "shanks.lead", at)
 		r := StuckReader{Builds: state(map[string]string{key: string(building), done: string(finished)}), ReAsks: state(map[string]string{key: string(reask)}),
-			Steps: map[string]StateRead{buildrun.GoBuildModule: state(map[string]string{}), ImageBuildModule: state(map[string]string{"g14.mvo53jcm70b5f8": string(running)})},
-			Now:   func() time.Time { return at.Add(time.Hour) }}
+			Steps:   map[string]StateRead{buildrun.GoBuildModule: state(map[string]string{}), ImageBuildModule: state(map[string]string{"g14.mvo53jcm70b5f8": string(running)})},
+			Hearing: state(map[string]string{buildrun.HearingKey: `{"heard":false,"streams":["SEAT_NODE_BUILD_GO"],"why":"DEAD_LETTERS is not heard: SEAT_NODE_BUILD_GO: permissions violation","at":"2026-10-26T13:00:00Z"}`}),
+			Now:     func() time.Time { return at.Add(time.Hour) }}
 		out, err := r.Stuck("")
 		if err != nil {
 			t.Fatal(err)
 		}
+		// Issue 734, review round 1: a builder that does not hear DEAD_LETTERS says so, with why.
+		if dl := out["dead_letters"].(map[string]any); dl["heard"] != false || !strings.Contains(dl["why"].(string), "permissions violation") {
+			t.Errorf("dead_letters = %v, want not heard, saying why", dl)
+		}
 		stuck := out["stuck"].([]Stuck)
 		if len(stuck) != 1 || stuck[0].Key != key || stuck[0].Age != "1h0m0s" || stuck[0].NoneStep != 1 || stuck[0].ReAsk == nil || stuck[0].ReAsk.Why != "stuck" {
 			t.Fatalf("stuck = %+v, want the building key alone, an hour old, one ask with no step, with its ask again", stuck)
@@ -959,3 +1102,10 @@ func TestATakeOverThatCannotReadTheStreamWaitsForTheAsk(t *testing.T) {
 		t.Fatalf("the key = %+v after %d asks, want done from the ask's step, none put", v, len(r.asks.Asks()))
 	}
 }
+
+// silentWatch is a watch of an ask's step that stays open and hears nothing.
+type silentWatch struct{}
+
+func (silentWatch) WatchAsk(context.Context, string, string) (<-chan delivery.Step, error) {
+	return make(chan delivery.Step), nil
+}

modules/mesh-delivery-builder/internal/build/stuck.go

@@ -22,6 +22,8 @@ import (
 const (
 	StuckTool    = "builder_stuck"
 	AskAgainTool = "builder_ask_again"
+	// BuildAgainTool builds a failed key again by hand (issue 1126 note 72): it writes a reasks value of Mode ModeBuild.
+	BuildAgainTool = "builder_build_again"
 	// ReAsksState is the builder's state of asks to ask again: the bucket mesh-delivery-builder_reasks, keyed as the build key.
 	ReAsksState  = "reasks"
 	ReAsksBucket = delivery.BuilderModule + "_" + ReAsksState
@@ -36,8 +38,24 @@ type ReAsk struct {
 	At       time.Time `json:"at"`
 	Answer   string    `json:"answer,omitempty"`
 	Answered time.Time `json:"answered,omitzero"`
+	// Mode is ModeBuild for a request to build a failed key again (BuildAgainTool); empty for an ask asked again.
+	Mode   string `json:"mode,omitempty"`
+	Module string `json:"module,omitempty"`
+	FP     string `json:"fp,omitempty"`
+	// Refused, Revision and Asks are the builder's answer to a ModeBuild request: why it did nothing, or the key's new
+	// revision (building) and the ask ids it put by language.
+	Refused bool `json:"refused,omitempty"`
+	// Pending says the builder answered before the key was claimed or all its asks were put: neither a refusal nor done.
+	// Failed is the error of a key written building that failed before its asks were put.
+	Pending  bool              `json:"pending,omitempty"`
+	Failed   string            `json:"failed,omitempty"`
+	Revision uint64            `json:"revision,omitempty"`
+	Asks     map[string]string `json:"asks,omitempty"`
 }
 
+// ModeBuild is the Mode of a reasks value that asks the key to be built again, not its waiting asks to be asked again.
+const ModeBuild = "build"
+
 // DecodeReAsk reads a reasks value.
 func DecodeReAsk(data []byte) (ReAsk, error) {
 	var r ReAsk
@@ -63,6 +81,19 @@ func NewReAsk(module, fp, why, by string, at time.Time) (string, []byte, error)
 	return key, data, err
 }
 
+// NewBuildAgain is the value builder_build_again writes for a module's fingerprint: its key and the value.
+func NewBuildAgain(module, fp, why, by string, at time.Time) (string, []byte, error) {
+	key, err := delivery.BuilderBuildKey(module, fp)
+	if err != nil {
+		return "", nil, err
+	}
+	if strings.TrimSpace(why) == "" {
+		return "", nil, errors.New("say why the key is built again (why)")
+	}
+	data, err := json.Marshal(ReAsk{V: 1, Why: strings.TrimSpace(why), By: by, At: at.UTC(), Mode: ModeBuild, Module: module, FP: fp})
+	return key, data, err
+}
+
 // StateRead is a state the tools read: its keys, and a key's value with when it was written (zero when not known).
 type StateRead struct {
 	Keys func() ([]string, error)
@@ -106,7 +137,9 @@ type StuckReader struct {
 	ReAsks StateRead
 	// Steps are the build modules' steps states, by build module.
 	Steps map[string]StateRead
-	Now   func() time.Time
+	// Hearing is the builder's state hearing: whether it hears DEAD_LETTERS (issue 734); without it none is said.
+	Hearing StateRead
+	Now     func() time.Time
 	// Logf, when set, gets the one line a call logs: the values it read and the time it took.
 	Logf func(format string, args ...any)
 }
@@ -149,6 +182,20 @@ func parallel(n int, read func(i int) error) error {
 }
 
 // Stuck is every key building or queued with its asks, oldest first; with module, that module's only.
+// deadLetters says whether the builder hears the asks the build seats give up on (issue 734), and why not: deaf, a lane
+// whose ask is given up waits for its check bound (buildrun.HearingHealth over the kept hearing).
+func (r StuckReader) deadLetters() map[string]any {
+	if r.Hearing.Get == nil {
+		return map[string]any{"heard": false, "why": "the builder's state hearing is not readable here"}
+	}
+	raw, _, err := r.Hearing.Get(buildrun.HearingKey)
+	if err != nil {
+		return map[string]any{"heard": false, "why": "the builder's state hearing cannot be read: " + err.Error()}
+	}
+	a := buildrun.HearingHealth(raw)
+	return map[string]any{"heard": a.Healthy, "why": a.Why}
+}
+
 func (r StuckReader) Stuck(module string) (map[string]any, error) {
 	started := time.Now()
 	reads := 0
@@ -268,6 +315,7 @@ func (r StuckReader) Stuck(module string) (map[string]any, error) {
 	})
 	answer := map[string]any{"stuck": out, "count": len(out),
 		"delivery_counts": "not readable by the builder: the build seats' workers' information is granted to the delivery view alone (its backlog); an ask given up on is told by the builder at its check bound and asked again"}
+	answer["dead_letters"] = r.deadLetters()
 	if cut {
 		answer["cut"], answer["note"] = true, fmt.Sprintf("read %d of %d build keys in key order and stopped; give a module to read its keys alone", MaxReads, total)
 	}

modules/mesh-delivery-builder/manifest_test.go

@@ -87,13 +87,13 @@ func TestManifestDeclarations(t *testing.T) { // 1607/AC1
 	if m.Module != "mesh-delivery-builder" {
 		t.Errorf("module = %q", m.Module)
 	}
-	if want := []state{{Name: "builds", History: 5}, {Name: "instances", History: 1}, {Name: "queues", History: 1}, {Name: "reasks", History: 1}}; !reflect.DeepEqual(m.State, want) { // delivery.BuilderBuildsHistory
+	if want := []state{{Name: "builds", History: 5}, {Name: "hearing", History: 1}, {Name: "instances", History: 1}, {Name: "queues", History: 1}, {Name: "reasks", History: 1}}; !reflect.DeepEqual(m.State, want) { // delivery.BuilderBuildsHistory
 		t.Errorf("state = %+v, want %+v", m.State, want)
 	}
 	// 1887/A4c: the builder chooses no node, so it reads neither presence nor have, invokes no build module's tool and
 	// holds no capacity; it puts asks on the three build seats and reads their steps (ADR 0525 §1, §4, §5).
-	if want := []string{"mesh-build-go.steps", "mesh-build-go.toolchains", "mesh-build-image.steps", "mesh-build-node.steps", "mesh-build-node.toolchains", "mesh-controller.assignments",
-		"mesh-delivery-gate.source", "mesh-delivery-indexer.candidates", "mesh-delivery-indexer.manifests", "mesh-delivery-indexer.modules"}; !reflect.DeepEqual(sorted(m.Reads), want) {
+	if want := []string{"mesh-build-go.steps", "mesh-build-go.toolchains", "mesh-build-image.steps", "mesh-build-node.steps", "mesh-build-node.toolchains",
+		"mesh-delivery-assigner.placement", "mesh-delivery-gate.source", "mesh-delivery-indexer.candidates", "mesh-delivery-indexer.manifests", "mesh-delivery-indexer.modules"}; !reflect.DeepEqual(sorted(m.Reads), want) {
 		t.Errorf("reads = %v, want %v", m.Reads, want)
 	}
 	if want := []string{"node-build-go", "node-build-image", "node-build-node"}; !reflect.DeepEqual(sorted(m.Uses), want) {
@@ -116,7 +116,7 @@ func TestManifestDeclarations(t *testing.T) { // 1607/AC1
 		t.Errorf("secrets-owner = %q", m.SecretsOwner)
 	}
 	// 1945: the builder's tools (builder_seat_queue: note 62), served by its tools bundle, and the event it says when it asks an ask again.
-	if want := []string{"builder_ask_again", "builder_seat_queue", "builder_stuck"}; !reflect.DeepEqual(sorted(m.Tools), want) {
+	if want := []string{"builder_ask_again", "builder_build_again", "builder_seat_queue", "builder_stuck"}; !reflect.DeepEqual(sorted(m.Tools), want) {
 		t.Errorf("tools = %v, want %v", m.Tools, want)
 	}
 	if want := []string{"build.asked-again"}; !reflect.DeepEqual(m.Emits, want) {

modules/mesh-delivery-builder/module.json

@@ -4,6 +4,7 @@
   "slug": "builder",
   "tools": [
     "builder_ask_again",
+    "builder_build_again",
     "builder_seat_queue",
     "builder_stuck"
   ],
@@ -20,6 +21,7 @@
   ],
   "state": [
     { "name": "builds", "history": 5 },
+    { "name": "hearing", "history": 1 },
     { "name": "instances", "history": 1 },
     { "name": "queues", "history": 1 },
     { "name": "reasks", "history": 1 }
@@ -30,7 +32,7 @@
     "mesh-build-image.steps",
     "mesh-build-node.steps",
     "mesh-build-node.toolchains",
-    "mesh-controller.assignments",
+    "mesh-delivery-assigner.placement",
     "mesh-delivery-gate.source",
     "mesh-delivery-indexer.candidates",
     "mesh-delivery-indexer.manifests",

modules/mesh-delivery-checker/cmd/mesh-delivery-checker-tools/main.go

@@ -1,6 +1,6 @@
 // Command mesh-delivery-checker-tools serves the checker's read tools (novox/hq ADR 0484 clause 13, issue 1686): the runtime
 // launches it for a call, it reads the checker's verdicts and kept states and the indexer's candidates through the checker's
-// state and reads, and writes nothing. The checker is the other program: it serves no tool (ADR 0437 §4).
+// state and reads. It writes only the tries (the try's tools) and, asking a check again by hand, one verdict. The checker is the other program: it serves no tool (ADR 0437 §4).
 package main
 
 import (
@@ -12,6 +12,7 @@ import (
 
 	stdio "git.novox.be/novox/mesh-sdk/go"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
+	"git.novox.be/novox/mesh-sdk/go/delivery/buildrun"
 
 	"mesh-delivery-checker/internal/check"
 )
@@ -53,10 +54,36 @@ func read(s stdio.KeptState) check.StateRead {
 	}}
 }
 
+// runsOf says which commit the mesh runs of a module from the indexer's modules state, as the checker's own record of it does
+// (the commit the module's record was computed at); "" when the record is not readable.
+type runsOf struct{ modules check.StateRead }
+
+func (r runsOf) CommitOf(module string) string {
+	if r.modules.Get == nil {
+		return ""
+	}
+	raw, err := r.modules.Get(module)
+	if err != nil || len(raw) == 0 {
+		return ""
+	}
+	m, err := delivery.DecodeModule(raw)
+	if err != nil {
+		return ""
+	}
+	return m.Commit
+}
+
 // stateStore is a state the tools write: the tries.
 type stateStore struct {
 	check.StateRead
 	create func(key string, value []byte) error
+	entry  func(key string) (json.RawMessage, uint64, error)
+	update func(key string, value []byte, revision uint64) error
+}
+
+func (s stateStore) Entry(key string) (json.RawMessage, uint64, error) { return s.entry(key) }
+func (s stateStore) Update(key string, value []byte, revision uint64) error {
+	return s.update(key, value, revision)
 }
 
 func (s stateStore) Keys() ([]string, error)                 { return s.StateRead.Keys() }
@@ -66,19 +93,21 @@ func (s stateStore) Create(key string, value []byte) error   { return s.create(k
 // Trying is what the try's tools work on: the tries, and the gate's trunk heads.
 type Trying struct {
 	Tries  check.TryStore
+	Ender  check.TryEnder
 	Trunks func() (map[string]string, error)
 	Now    func() time.Time
 }
 
-// TryTools are the try's two tools (ADR 0501 §5): ask one, read one. mesh-controller's try calls them.
+// TryTools are the try's tools (ADR 0501 §5): ask one, read one, and end one by hand (issue 734). mesh-controller's try calls them.
 func TryTools(tr Trying) []stdio.Tool {
 	str := func(args map[string]any, k string) string { s, _ := args[k].(string); return s }
 	return []stdio.Tool{
 		{Name: check.TryTool,
 			Description: "Try a pushed head before its pull request is opened: the checker judges it as it judges a pull request's head, merged onto its trunk's head, " +
 				"its unit and integration levels through the build modules, and owes the forge nothing. Answers the try's id at once; " + check.TryReadTool + " reads " +
-				"where it stands. A try of the same head that waits or runs is the answer to a second ask; at most 4 wait or run at once, mesh-wide. A repository " +
-				"the checker checks no level of (one whose trunk the gate does not name) is refused.",
+				"where it stands. A try of the same head that waits or runs is the answer to a second ask; a new try is refused while 4 tries run on a build node or 8 wait for one, mesh-wide; tries let in while waiting may later all run at once, and each node's build capacity bounds what runs on it. A repository " +
+				"the checker checks no level of (one whose trunk the gate does not name) is refused. A try whose ask no build node took within the step " +
+				"bound ends as error; its ask stays in the build seat's stream and may still run later, judged by nobody (issue 734).",
 			Input: map[string]any{"type": "object", "required": []string{"repository", "head"}, "properties": map[string]any{
 				"repository": map[string]any{"type": "string", "description": "<owner>/<name>"},
 				"head":       map[string]any{"type": "string", "description": "the full commit to try, 40 or 64 hex digits"},
@@ -106,7 +135,8 @@ func TryTools(tr Trying) []stdio.Tool {
 			}},
 		{Name: check.TryReadTool,
 			Description: "Where a try stands, as stored: queued, running, or its end (pass, fail, or error when it could not run), with what was said of it, " +
-				"the head and the trunk commit it was merged onto, the time it took and what failed first. Read-only.",
+				"the head and the trunk commit it was merged onto, the time it took and what failed first; while it runs, each ask it put as soon as it is put, " +
+				"with the node that took it, its state and the phase its step says (fetch and merge, a level's digest, lint, tests) and since when. Read-only.",
 			Input: map[string]any{"type": "object", "required": []string{"id"}, "properties": map[string]any{
 				"id": map[string]any{"type": "string", "description": "the try's id, try-<digits>"}}},
 			Run: func(args map[string]any) (any, error) {
@@ -115,9 +145,46 @@ func TryTools(tr Trying) []stdio.Tool {
 				}
 				return check.ReadTry(tr.Tries, str(args, "id"))
 			}},
+		{Name: check.TryEndTool,
+			Description: "End a try that waits or runs, as error, by hand: say why (kept in what it says). Its place among the 4 is free at once, " +
+				"the checker stops waiting for its asks, and the next " + check.TryTool + " of its head asks anew with a new id. For a try whose ask " +
+				"was lost (no step runs for it in checker_status); the checker ends one by itself when the build seat gives its ask up, or no node " +
+				"takes it within the step bound. A try that ended already is refused.",
+			Input: map[string]any{"type": "object", "required": []string{"id", "why"}, "properties": map[string]any{
+				"id":  map[string]any{"type": "string", "description": "the try's id, try-<digits>"},
+				"why": map[string]any{"type": "string", "description": "why it is ended, in words"}}},
+			Run: func(args map[string]any) (any, error) {
+				if tr.Ender == nil {
+					return nil, fmt.Errorf("the tries state cannot be written here")
+				}
+				now := time.Now
+				if tr.Now != nil {
+					now = tr.Now
+				}
+				t, err := check.EndTry(tr.Ender, str(args, "id"), str(args, "why"), now())
+				if err != nil {
+					return nil, err
+				}
+				return map[string]any{"id": t.ID, "state": t.State, "said": t.Said}, nil
+			}},
 	}
 }
 
+// Seat is the seat the checker holds (novox/hq ADR 0547 §10, issue 774); its verbs are served as tools named <seat>.<verb>.
+const Seat = "mesh-delivery-checker"
+
+// SeatTryTools are the try's tools as the seat's verbs: try, try-read and try-end, run by the same code as checker_try,
+// checker_try_read and checker_try_end, so the answer is the same. The module tools stay beside them.
+func SeatTryTools(tr Trying) []stdio.Tool {
+	verbs := map[string]string{check.TryTool: "try", check.TryReadTool: "try-read", check.TryEndTool: "try-end"}
+	var out []stdio.Tool
+	for _, t := range TryTools(tr) {
+		t.Name = Seat + "." + verbs[t.Name]
+		out = append(out, t)
+	}
+	return out
+}
+
 // Tools are the read tools over the checker's states.
 func Tools(r check.Reader) []stdio.Tool {
 	return []stdio.Tool{
@@ -174,12 +241,33 @@ func Tools(r check.Reader) []stdio.Tool {
 				"and the candidates whose check is owed by kind (waiting_by_kind: new, nodes, and trunk, a re-judge pulled after the other two). A key a " +
 				"build module left running (started past the step bound, or its build module not running on its node) is listed apart under " +
 				"left_running with why, and not counted. Nothing holds the checker and it has no capacity of its own: a check is an ask on the " +
-				"build seats' streams, whose backlog the delivery view shows (novox/hq ADR 0525). Read-only.",
+				"build seats' streams, whose backlog the delivery view shows (novox/hq ADR 0525). held_by_turn names the candidates whose check an approved " +
+				"merge's turn holds off (novox/hq ADR 0548 §3), with the repository and the merge that waits; the gate's turns tool reads every turn and its " +
+				"hand-now tool steers one. dead_letters says whether the checker hears the asks the build seats give up on (issue 734), and why not: " +
+				"deaf, a try or check whose ask is given up waits until its bound. Read-only.",
 			Input: map[string]any{"type": "object", "properties": map[string]any{}},
 			Run:   func(map[string]any) (any, error) { return r.Status() }},
 	}
 }
 
+// RecoveryTools are the tools that steer a check by hand (tools-are-how-a-module-is-spoken-to): ask a check again whose
+// wait judged nothing (the lost check of 2026-10-28). They write the checker's verdicts through w.
+func RecoveryTools(r check.Reader, w check.VerdictEntry) []stdio.Tool {
+	str := func(args map[string]any, k string) string { s, _ := args[k].(string); return s }
+	return []stdio.Tool{{Name: check.AskAgainTool,
+		Description: "Ask a candidate's check again by hand, whose verdict stays running while nothing runs for it (" + check.StatusReadTool + " names it " +
+			"under lost): its verdict is ended as asked again, saying why, and the checker, which hears its verdicts, stops the wait that judged nothing " +
+			"and asks the check anew, whole. Refused for a group with no candidate, a verdict that is not running (a pass or failure stands until a push or " +
+			"a trunk move), and while a step of its pull requests can still run on a build module (its end judges it). The checker reads a step that " +
+			"ended while its watch was deaf by itself at the next step end of its build module; this is for what that does not reach.",
+		Input: map[string]any{"type": "object", "required": []string{"group", "why"}, "properties": map[string]any{
+			"group": map[string]any{"type": "string", "description": "the delivery group's branch name"},
+			"why":   map[string]any{"type": "string", "description": "why it is asked again, in words; kept in the verdict it ends"}}},
+		Run: func(args map[string]any) (any, error) {
+			return r.AskAgain(w, str(args, "group"), str(args, "why"))
+		}}}
+}
+
 // stepBound is the checker's step bound as the checker reads it (MESH_CHECKER_STEP_BOUND), its default when unset or not a
 // duration.
 func stepBound() time.Duration {
@@ -193,7 +281,10 @@ func main() {
 	r := check.Reader{VerdictState: read(stdio.State("verdicts")), KeptState: read(stdio.State("kept")), CandidateState: read(stdio.State("mesh-delivery-indexer.candidates")),
 		PreviewState: read(stdio.State("previews")),
 		StepStates:   map[string]check.StateRead{"mesh-build-go": read(stdio.State("mesh-build-go.steps")), "mesh-build-node": read(stdio.State("mesh-build-node.steps"))},
-		HaveState:    read(stdio.State("node-engine.have")), StepBound: stepBound()}
+		HaveState:    read(stdio.State("node-engine.have")), StepBound: stepBound(),
+		TurnState: read(stdio.State("mesh-delivery-gate.turns")), HearingState: read(stdio.State(buildrun.HearingState)),
+		AskState: read(stdio.State(check.AsksState))}
+	r.Runs = runsOf{read(stdio.State("mesh-delivery-indexer.modules"))} // the node-engine at the commit the mesh runs, as the checker reads it
 	tries := stdio.State(check.TriesState)
 	source := stdio.State("mesh-delivery-gate.source")
 	trunks := func() (map[string]string, error) {
@@ -205,14 +296,35 @@ func main() {
 		return s.Heads, err
 	}
 	r.Trunks = trunks
-	trying := Trying{
-		Tries: stateStore{StateRead: read(tries), create: func(key string, value []byte) error {
-			_, err := tries.Create(key, json.RawMessage(value))
-			return err
-		}},
-		Trunks: trunks,
-	}
-	if err := stdio.Serve("", logged(append(Tools(r), TryTools(trying)...))); err != nil {
+	store := stateStore{StateRead: read(tries), create: func(key string, value []byte) error {
+		_, err := tries.Create(key, json.RawMessage(value))
+		return err
+	}, entry: func(key string) (json.RawMessage, uint64, error) {
+		reads.Add(1)
+		e, err := tries.Get(key)
+		if err != nil || e == nil {
+			return nil, 0, err
+		}
+		return e.Value, e.Revision, nil
+	}, update: func(key string, value []byte, revision uint64) error {
+		_, err := tries.Update(key, json.RawMessage(value), revision)
+		return err
+	}}
+	trying := Trying{Tries: store, Ender: store, Trunks: trunks}
+	verdicts := stdio.State("verdicts")
+	written := stateStore{entry: func(key string) (json.RawMessage, uint64, error) {
+		reads.Add(1)
+		e, err := verdicts.Get(key)
+		if err != nil || e == nil {
+			return nil, 0, err
+		}
+		return e.Value, e.Revision, nil
+	}, update: func(key string, value []byte, revision uint64) error {
+		_, err := verdicts.Update(key, json.RawMessage(value), revision)
+		return err
+	}}
+	tools := append(append(append(Tools(r), TryTools(trying)...), SeatTryTools(trying)...), RecoveryTools(r, written)...)
+	if err := stdio.Serve("", logged(tools)); err != nil {
 		fmt.Fprintf(os.Stderr, "[mesh-delivery-checker-tools] %v\n", err)
 		os.Exit(1)
 	}

modules/mesh-delivery-checker/cmd/mesh-delivery-checker-tools/main_test.go

@@ -23,6 +23,14 @@ func TestTheToolsServedAreTheFiveReadTools(t *testing.T) {
 	if !slices.Equal(names, want) {
 		t.Errorf("tools = %v, want %v", names, want)
 	}
+	// The recovery tool beside them asks a lost check again; with nothing to write it refuses.
+	recovery := RecoveryTools(check.Reader{}, nil)
+	if len(recovery) != 1 || recovery[0].Name != check.AskAgainTool || recovery[0].Description == "" {
+		t.Errorf("recovery tools = %+v", recovery)
+	}
+	if _, err := recovery[0].Run(map[string]any{"group": "feat/x", "why": "lost"}); err == nil {
+		t.Errorf("%s answered with no state to write", check.AskAgainTool)
+	}
 	// With nothing to read from a tool says so and changes nothing.
 	for _, tl := range Tools(check.Reader{}) {
 		if tl.Name == check.StatusReadTool {
@@ -53,13 +61,19 @@ func (m *memStore) Create(key string, value []byte) error {
 	return nil
 }
 
+func (m *memStore) Entry(key string) (json.RawMessage, uint64, error) { return m.vals[key], 1, nil }
+func (m *memStore) Update(key string, value []byte, revision uint64) error {
+	m.vals[key] = value
+	return nil
+}
+
 func TestTheTryToolsAskAndReadATry(t *testing.T) { // ADR 0501 §5, the agreed interface with mesh-controller's try
 	store := &memStore{vals: map[string]json.RawMessage{}}
-	tools := TryTools(Trying{Tries: store, Now: func() time.Time { return time.Unix(1, 5) },
+	tools := TryTools(Trying{Tries: store, Ender: store, Now: func() time.Time { return time.Unix(1, 5) },
 		Trunks: func() (map[string]string, error) {
 			return map[string]string{"novox/mesh-delivery": strings.Repeat("a", 40)}, nil
 		}})
-	if len(tools) != 2 || tools[0].Name != "checker_try" || tools[1].Name != "checker_try_read" {
+	if len(tools) != 3 || tools[0].Name != "checker_try" || tools[1].Name != "checker_try_read" || tools[2].Name != "checker_try_end" {
 		t.Fatalf("tools = %+v", tools)
 	}
 	out, err := tools[0].Run(map[string]any{"repository": "novox/mesh-delivery", "head": strings.Repeat("1", 40), "trunk": "main"})
@@ -74,6 +88,32 @@ func TestTheTryToolsAskAndReadATry(t *testing.T) { // ADR 0501 §5, the agreed i
 	if err != nil || !strings.Contains(string(raw.(json.RawMessage)), `"state":"queued"`) {
 		t.Errorf("read = %s, %v", raw, err)
 	}
+	// The seat's verbs answer as the tools do (ADR 0547 §10, issue 774): the same ask is the same try, and the read is alike.
+	verbs := SeatTryTools(Trying{Tries: store, Ender: store, Now: func() time.Time { return time.Unix(1, 5) },
+		Trunks: func() (map[string]string, error) {
+			return map[string]string{"novox/mesh-delivery": strings.Repeat("a", 40)}, nil
+		}})
+	if len(verbs) != 3 || verbs[0].Name != Seat+".try" || verbs[1].Name != Seat+".try-read" || verbs[2].Name != Seat+".try-end" {
+		t.Fatalf("verbs = %+v", verbs)
+	}
+	again, err := verbs[0].Run(map[string]any{"repository": "novox/mesh-delivery", "head": strings.Repeat("1", 40), "trunk": "main"})
+	if err != nil || again.(map[string]any)["id"] != id {
+		t.Errorf("verb try = %v, %v, want the waiting try %s", again, err, id)
+	}
+	if viaVerb, err := verbs[1].Run(map[string]any{"id": id}); err != nil || string(viaVerb.(json.RawMessage)) != string(raw.(json.RawMessage)) {
+		t.Errorf("verb try-read = %s, %v; tool = %s", viaVerb, err, raw)
+	}
+	if _, err := verbs[0].Run(map[string]any{"repository": "novox/hq", "head": strings.Repeat("1", 40)}); err == nil {
+		t.Error("the verb tried a repository nothing checks")
+	}
+	// Issue 734: a try whose ask was lost is ended by hand with why, and its head is asked anew.
+	ended, err := tools[2].Run(map[string]any{"id": id, "why": "its ask was lost"})
+	if err != nil || ended.(map[string]any)["state"] != "error" {
+		t.Errorf("end = %v, %v", ended, err)
+	}
+	if _, err := tools[2].Run(map[string]any{"id": id, "why": "again"}); err == nil {
+		t.Error("an ended try was ended again")
+	}
 	if _, err := tools[0].Run(map[string]any{"repository": "novox/hq", "head": strings.Repeat("1", 40)}); err == nil ||
 		err.Error() != "no level of novox/hq is checked by the checker" {
 		t.Errorf("hq: %v", err)

modules/mesh-delivery-checker/cmd/mesh-delivery-checker/bus.go

@@ -9,6 +9,7 @@ import (
 
 	"git.novox.be/novox/mesh-sdk/go/catalogue"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
+	"git.novox.be/novox/mesh-sdk/go/process"
 
 	"mesh-delivery-checker/internal/check"
 )
@@ -130,3 +131,55 @@ func (m manifestReader) Manifest(ctx context.Context, digest string) (catalogue.
 func parseManifest(raw string) (catalogue.Manifest, error) {
 	return catalogue.ParseManifestForInputs([]byte(raw))
 }
+
+// awaitedKV is a bucket that may appear after the start (process.AwaitBucket) as a check.KV: a call while it is not on the
+// bus fails saying so.
+type awaitedKV struct{ b *process.AwaitedBucket }
+
+func (a awaitedKV) kv() (kvStore, error) {
+	kv := a.b.KV()
+	if kv == nil {
+		return kvStore{}, errors.New("the bucket is not on the bus yet")
+	}
+	return kvStore{kv}, nil
+}
+
+func (a awaitedKV) Get(ctx context.Context, key string) ([]byte, uint64, bool, error) {
+	s, err := a.kv()
+	if err != nil {
+		return nil, 0, false, err
+	}
+	return s.Get(ctx, key)
+}
+
+func (a awaitedKV) Create(ctx context.Context, key string, value []byte) (uint64, error) {
+	s, err := a.kv()
+	if err != nil {
+		return 0, err
+	}
+	return s.Create(ctx, key, value)
+}
+
+func (a awaitedKV) Update(ctx context.Context, key string, value []byte, revision uint64) (uint64, error) {
+	s, err := a.kv()
+	if err != nil {
+		return 0, err
+	}
+	return s.Update(ctx, key, value, revision)
+}
+
+func (a awaitedKV) Keys(ctx context.Context) ([]string, error) {
+	s, err := a.kv()
+	if err != nil {
+		return nil, err
+	}
+	return s.Keys(ctx)
+}
+
+func (a awaitedKV) Delete(ctx context.Context, key string) error {
+	s, err := a.kv()
+	if err != nil {
+		return err
+	}
+	return s.Delete(ctx, key)
+}

modules/mesh-delivery-checker/cmd/mesh-delivery-checker/integration_test.go

@@ -24,6 +24,8 @@ import (
 	"git.novox.be/novox/mesh-sdk/go/announce"
 	"git.novox.be/novox/mesh-sdk/go/buildstep"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
+	"git.novox.be/novox/mesh-sdk/go/delivery/buildrun"
+	"git.novox.be/novox/mesh-sdk/go/process"
 
 	"mesh-delivery-checker/internal/check"
 )
@@ -79,12 +81,16 @@ type fakeBuildModules struct {
 	js       jetstream.JetStream
 	ctx      context.Context
 	conflict atomic.Bool
+	// hold is a commit whose fetch never answers: its ask stays taken, as one lost in a bus reload (issue 734).
+	hold     atomic.Value
 	mu       sync.Mutex
 	calls    map[string]int // by `<module>.<tool>`
 	testTool *testing.T
 	// beside is, by workspace, the siblings the fetch placed in it as `<owner/repo> <commit>`, sorted: a digest echoes them
 	// (1929/AC2; mesh-sdk buildstep.besideOf), or the level runs whole and keeps nothing.
 	beside map[string][]string
+	// names are the nodes' names the last check ask carried, for the names check (ADR 0567 §12).
+	names []string
 }
 
 func (f *fakeBuildModules) count(tool string) int {
@@ -98,6 +104,9 @@ func (f *fakeBuildModules) result(t *testing.T, tool string, args map[string]any
 	var v any
 	switch {
 	case strings.HasSuffix(tool, "_fetch"):
+		if h, _ := f.hold.Load().(string); h != "" && args["commit"] == h {
+			<-f.ctx.Done()
+		}
 		name := "go-fetch-clean"
 		if f.conflict.Load() {
 			name = "go-fetch-conflict"
@@ -184,7 +193,14 @@ func (f *fakeBuildModules) serve(t *testing.T, module string, kept jetstream.Key
 	}
 	p := &buildstep.Puller{Source: &buildstep.JetStreamAsks{JS: f.js, Language: language}, Language: language, Node: "n1", Put: put,
 		Capacity: func() int { return 2 }, PullWait: 200 * time.Millisecond,
-		Run: func(ctx context.Context, a delivery.StepAsk) (any, error) { return buildstep.RunAsk(ctx, steps, a) }}
+		Run: func(ctx context.Context, a delivery.StepAsk) (any, error) {
+			if a.Check != nil {
+				f.mu.Lock()
+				f.names = a.Check.NodeNames
+				f.mu.Unlock()
+			}
+			return buildstep.RunAsk(ctx, steps, a)
+		}}
 	go func() { _ = p.Pull(f.ctx) }()
 }
 
@@ -298,6 +314,10 @@ func startBed(t *testing.T) *bed {
 		}
 		b.tools[module] = kv
 	}
+	// What the controller keeps of the messages a consumer gave up on (issue 734).
+	if _, err := js.CreateStream(ctx, jetstream.StreamConfig{Name: buildrun.DeadLettersStream, Subjects: []string{"mesh.events.dead.>"}}); err != nil {
+		t.Fatal(err)
+	}
 	// The checker's stream of events, which the indexer and the forge bridge hear.
 	if _, err := js.CreateStream(ctx, jetstream.StreamConfig{Name: "CHECKS", Subjects: []string{"mesh.stream.mesh-delivery-checker.event.>"}}); err != nil {
 		t.Fatal(err)
@@ -305,7 +325,8 @@ func startBed(t *testing.T) *bed {
 	for name, history := range map[string]int{delivery.CheckerVerdictsBucket: delivery.CheckerVerdictsHistory, delivery.CheckerKeptBucket: delivery.CheckerKeptHistory,
 		delivery.CheckerOwedBucket: delivery.CheckerOwedHistory, delivery.PreviewsBucket: delivery.PreviewsHistory, delivery.CandidatesBucket: delivery.CandidatesHistory,
 		delivery.ModulesBucket: delivery.ModulesHistory, delivery.ManifestsBucket: delivery.ManifestsHistory, delivery.SourceBucket: delivery.SourceHistory,
-		delivery.PresenceBucket: delivery.PresenceHistory, delivery.HaveBucket: delivery.HaveHistory, check.TriesBucket: 1} {
+		delivery.PresenceBucket: delivery.PresenceHistory, delivery.HaveBucket: delivery.HaveHistory, check.TriesBucket: 1,
+		delivery.TurnsBucket: delivery.TurnsHistory} {
 		kv, err := js.CreateKeyValue(ctx, jetstream.KeyValueConfig{Bucket: name, History: uint8(history)})
 		if err != nil {
 			t.Fatal(err)
@@ -322,6 +343,7 @@ func startBed(t *testing.T) *bed {
 		t.Fatal(err)
 	}
 	b.setOnline(t, "n1", true)
+	b.setNode(t, "n1")
 	for _, module := range []string{"mesh-build-go", "mesh-build-node"} {
 		b.setHealth(t, "n1", module)
 	}
@@ -354,6 +376,20 @@ func (b *bed) setOnline(t *testing.T, node string, online bool) {
 	}
 }
 
+// setNode writes the node's record in the node-engine's have, as the node-engine does, so the checker names it in each
+// check ask (ADR 0567 §12); with no record the checker asks no check.
+func (b *bed) setNode(t *testing.T, node string) {
+	t.Helper()
+	data, err := delivery.EncodeNodeRecord(delivery.NodeRecord{V: 1, Node: node})
+	if err != nil {
+		t.Fatal(err)
+	}
+	key, _ := delivery.HaveNodeKey(node)
+	if _, err := b.buckets[delivery.HaveBucket].Put(b.ctx, key, data); err != nil {
+		t.Fatal(err)
+	}
+}
+
 func (b *bed) setHealth(t *testing.T, node, module string) {
 	t.Helper()
 	data, err := delivery.EncodeHave(delivery.Have{Phase: delivery.PhaseRunning, Health: delivery.HealthOK})
@@ -412,11 +448,12 @@ func pull(repository string, number int, head string) delivery.CandidatePull {
 func (b *bed) start(t *testing.T, env map[string]string) {
 	t.Helper()
 	broker := filepath.Join(t.TempDir(), "broker")
-	cred, _ := json.Marshal(credential{URL: b.srvURL, Node: "n1", Module: "mesh-delivery-checker", User: "n1.mesh-delivery-checker", Password: "pw"})
+	cred, _ := json.Marshal(process.Account{URL: b.srvURL, Node: "n1", Module: "mesh-delivery-checker", User: "n1.mesh-delivery-checker", Password: "pw"})
 	if err := os.WriteFile(broker, cred, 0o600); err != nil {
 		t.Fatal(err)
 	}
-	e := map[string]string{"MESH_BROKER_FILE": broker}
+	// The settle window of a group's heads (check.DefaultSettle) is cut short: each bed's candidate is written whole.
+	e := map[string]string{"MESH_BROKER_FILE": broker, "MESH_CHECKER_SETTLE": "10ms"}
 	for k, v := range env {
 		e[k] = v
 	}
@@ -480,6 +517,12 @@ func TestCheckerJudgesACandidateAndOwesItsStatus(t *testing.T) { // N6/AC5, 1300
 	if v.Composition == nil || v.Composition.State != delivery.CompositionNotRun || len(v.Machines) != 1 || v.Machines[0] != "n1" {
 		t.Errorf("composition %+v machines %v", v.Composition, v.Machines)
 	}
+	b.fake.mu.Lock()
+	names := b.fake.names
+	b.fake.mu.Unlock()
+	if len(names) != 1 || names[0] != "n1" {
+		t.Errorf("the check ask named the nodes %v, want [n1] from the have's node record", names)
+	}
 	o := b.owed(t, 7, head1, "success")
 	if o.Context != delivery.StatusContextCheck || !strings.HasPrefix(o.Text, "pass 111111111111 on aaaaaaaaaaaa") || !strings.Contains(o.Text, "unit 2 run") {
 		t.Errorf("owed = %+v", o)
@@ -507,9 +550,12 @@ func TestCheckerJudgesACandidateAndOwesItsStatus(t *testing.T) { // N6/AC5, 1300
 	}
 }
 
-// TestACheckOfEqualInputsRunsNothing: a second candidate (another head, the same digests) is checked with every package
-// taken from the first's kept verdicts: no test step runs and no second kept key appears.
-func TestACheckOfEqualInputsRunsNothing(t *testing.T) { // 1287/AC5, 1288/AC6, 1929/AC2
+// TestACheckOrACarryOfEqualInputsRunsNothing: a second candidate (another head, the same digests) is checked with every
+// package taken from the first's kept verdicts: no test step runs and no second kept key appears. Then, through the real bus
+// (novox/hq ADR 0548 §3, §5): a third candidate is not claimed while the gate's merge turn on its repository stands, and is
+// claimed when the turn's key is deleted; and a move of the trunk carries the first verdict on the recheck stream by its
+// unchanged digests, running no test, the verdict naming the trunk it was carried from.
+func TestACheckOrACarryOfEqualInputsRunsNothing(t *testing.T) { // 1287/AC5, 1288/AC6, 1929/AC2, ADR 0548 §3, §5
 	b := startBed(t)
 	first := b.candidate(t, "feat/x", pull(repo, 7, head1))
 	b.start(t, nil)
@@ -526,6 +572,42 @@ func TestACheckOfEqualInputsRunsNothing(t *testing.T) { // 1287/AC5, 1288/AC6, 1
 	if got := keptCount(t, b); got != kept {
 		t.Errorf("%d kept keys, was %d", got, kept)
 	}
+
+	// §3: the gate's turn on the repository holds a new check off; its delete claims it.
+	at := time.Now().UTC()
+	turn, err := delivery.EncodeTurn(delivery.Turn{Repository: repo, Waiting: []delivery.TurnWait{{Group: "fix/other", Heads: "0123456789ab", Approved: at, Since: at}}})
+	if err != nil {
+		t.Fatal(err)
+	}
+	tk, _ := delivery.TurnsKey(repo)
+	if _, err := b.buckets[delivery.TurnsBucket].Put(b.ctx, tk, turn); err != nil {
+		t.Fatal(err)
+	}
+	time.Sleep(300 * time.Millisecond) // the checker hears the turn
+	third := b.candidate(t, "feat/z", pull(repo, 9, "3333333333333333333333333333333333333333"))
+	time.Sleep(time.Second)
+	if _, err := b.buckets[delivery.CheckerVerdictsBucket].Get(b.ctx, third); !errors.Is(err, jetstream.ErrKeyNotFound) {
+		t.Fatalf("verdicts.%s exists (%v) while a merge turn holds its repository", third, err)
+	}
+	if err := b.buckets[delivery.TurnsBucket].Delete(b.ctx, tk); err != nil {
+		t.Fatal(err)
+	}
+	b.verdict(t, third, ended)
+
+	// §5: the trunk moves; the first verdict is carried by its digests, nothing runs.
+	tests = b.fake.count("mesh-build-go.build_go_test")
+	const moved = "abababababababababababababababababababab"
+	b.setTrunk(t, map[string]string{repo: moved})
+	c := b.verdict(t, first, func(v delivery.Verdict) bool { return ended(v) && v.Trunk[repo] == moved })
+	if c.State != delivery.VerdictPass || c.CarriedFrom[repo] != trunk || c.Levels[delivery.LevelUnit].Run != 0 || c.Levels[delivery.LevelIntegration].Run != 0 {
+		t.Fatalf("the carried verdict = %+v, want a pass carried from %s with no test run", c, trunk[:12])
+	}
+	if got := b.fake.count("mesh-build-go.build_go_test"); got != tests {
+		t.Errorf("build_go_test called %d times on the carry, was %d: a carry of unchanged digests runs nothing", got, tests)
+	}
+	if o := b.owed(t, 7, head1, "success"); !strings.HasPrefix(o.Text, "pass 111111111111 on abababababab | carried from aaaaaaaaaaaa") {
+		t.Errorf("the carried status says %q", o.Text)
+	}
 }
 
 func keptCount(t *testing.T, b *bed) int {
@@ -676,6 +758,49 @@ func TestATryIsJudgedAndItsEndWrittenWithNoStatusOwed(t *testing.T) {
 			t.Errorf("a try wrote %s: %v", name, keys)
 		}
 	}
+	// Issue 734: a try whose ask the build seat gives up on (the controller keeps its copy in DEAD_LETTERS with the ask's
+	// message id) ends as error saying so, and its head asked again is a new try.
+	b.fake.hold.Store(head2)
+	lost, err := check.AskTry(store, map[string]string{repo: trunk}, check.TryAsk{Repository: repo, Head: head2}, time.Now())
+	if err != nil {
+		t.Fatal(err)
+	}
+	steps, err := b.js.KeyValue(b.ctx, delivery.StepsBucket("mesh-build-go"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	askID := ""
+	for deadline := time.Now().Add(20 * time.Second); askID == "" && time.Now().Before(deadline); time.Sleep(50 * time.Millisecond) {
+		keys, _ := steps.Keys(b.ctx)
+		for _, k := range keys {
+			if e, err := steps.Get(b.ctx, k); err == nil && strings.Contains(string(e.Value()), `"running"`) {
+				askID = strings.TrimPrefix(k, "n1.")
+			}
+		}
+	}
+	if askID == "" {
+		t.Fatal("the held try's ask was never taken")
+	}
+	dead := &nats.Msg{Subject: "mesh.events.dead.SEAT_NODE_BUILD_GO.SEAT_NODE_BUILD_GO_CHECK_worker", Header: nats.Header{}}
+	dead.Header.Set(buildrun.DeadHeaderMsgID, askID)
+	dead.Header.Set(buildrun.DeadHeaderDeliveries, "5")
+	dead.Header.Set(buildrun.DeadHeaderStream, "SEAT_NODE_BUILD_GO")
+	dead.Header.Set(buildrun.DeadHeaderGaveUp, time.Now().UTC().Format(time.RFC3339Nano))
+	if _, err := b.js.PublishMsg(b.ctx, dead); err != nil {
+		t.Fatal(err)
+	}
+	for deadline := time.Now().Add(20 * time.Second); time.Now().Before(deadline); time.Sleep(50 * time.Millisecond) {
+		raw, _ := store.Get(lost)
+		if last, err = check.DecodeTry(raw); err == nil && last.Over() {
+			break
+		}
+	}
+	if last.State != check.TryError || !strings.Contains(last.Said, buildrun.LostWords+" after 5 deliveries") {
+		t.Fatalf("the try whose ask was given up = %+v, want error saying so", last)
+	}
+	if again, err := check.AskTry(store, map[string]string{repo: trunk}, check.TryAsk{Repository: repo, Head: head2}, time.Now()); err != nil || again == lost {
+		t.Errorf("its head asked again answered %q, %v, want a new try", again, err)
+	}
 }
 
 // TestTheCheckerSaysOwedReadableOnTheBus: started, the checker says on its own states subject what it keeps, owed among
@@ -702,7 +827,8 @@ func TestTheCheckerSaysOwedReadableOnTheBus(t *testing.T) { // R2-1
 		break
 	}
 	if said.Module != "mesh-delivery-checker" || said.Node != "n1" || !said.Keeps("owed") || !said.Readable("owed") ||
-		!said.Readable("previews") || !said.Readable("verdicts") || !said.Readable("kept") || said.Readable("tries") || len(said.States) != 5 {
-		t.Fatalf("the checker said %+v, want its five states with kept, owed, previews and verdicts readable (1929/AC4; 1887 A5b)", said)
+		!said.Readable("previews") || !said.Readable("verdicts") || !said.Readable("kept") || !said.Readable("tries") || said.Readable("hearing") ||
+		!said.Keeps("asks") || said.Readable("asks") || len(said.States) != 7 {
+		t.Fatalf("the checker said %+v, want its seven states, asks and hearing its own, with kept, owed, previews, tries and verdicts readable, tries by the delivery view (1929/AC4; 1887 A5b; build_usage)", said)
 	}
 }

modules/mesh-delivery-checker/cmd/mesh-delivery-checker/judge.go

@@ -2,12 +2,16 @@ package main
 
 import (
 	"context"
+	"fmt"
 	"sort"
 	"strings"
 	"sync"
 
+	"github.com/nats-io/nats.go/jetstream"
+
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 	"git.novox.be/novox/mesh-sdk/go/delivery/buildrun"
+	"git.novox.be/novox/mesh-sdk/go/process"
 
 	"mesh-delivery-checker/internal/check"
 )
@@ -25,11 +29,46 @@ type judgeDeps struct {
 	builds   check.BuildStates
 	// compositions is the assigner's bucket of compositions; nil leaves every composition not run.
 	compositions check.CompositionReader
-	logf         func(format string, args ...any)
+	// nodes names every node with a record; nil hands no names.
+	nodes *nodeNames
+	logf  func(format string, args ...any)
+}
+
+// nodeNames reads every node's name from the node-engine's have, one key `<node>.node` per node with a record (novox/hq
+// ADR 0567 §12), at each ask: a node enrolled since is named in the next check.
+type nodeNames struct{ kv jetstream.KeyValue }
+
+// openNodeNames opens the node-engine's have for the nodes' names alone: it is not watched, so no check waits on a node.
+func openNodeNames(ctx context.Context, js process.BucketOpener, logf func(string, ...any)) *nodeNames {
+	return &nodeNames{kv: process.OptionalBucket(ctx, js, delivery.HaveBucket, "no check is asked until it is: the names check needs the nodes' names", logf)}
+}
+
+func (n nodeNames) Names(ctx context.Context) ([]string, error) {
+	if n.kv == nil {
+		return nil, fmt.Errorf("the bucket %s could not be opened at the checker's start", delivery.HaveBucket)
+	}
+	lister, err := n.kv.ListKeysFiltered(ctx, "*."+delivery.HaveNodeWord)
+	if err != nil {
+		return nil, err
+	}
+	var out []string
+	for key := range lister.Keys() {
+		if node, _, isNode, err := delivery.ParseHaveKey(key); err == nil && isNode {
+			out = append(out, node)
+		}
+	}
+	sort.Strings(out)
+	return out, nil
 }
 
 func newJudge(d judgeDeps) check.Judge {
-	return &check.Examiner{Compositions: d.compositions, Asks: d.asks, Toolchains: d.tools,
+	var nodes interface {
+		Names(ctx context.Context) ([]string, error)
+	}
+	if d.nodes != nil {
+		nodes = d.nodes
+	}
+	return &check.Examiner{Nodes: nodes, Compositions: d.compositions, Asks: d.asks, Toolchains: d.tools,
 		Kept: check.Kept{Store: d.kept}, Previews: d.previews, Modules: d.repos, Packages: d.repos, Forge: d.forge, Runs: d.repos, Builds: d.builds, Announce: d.announce, Trunks: d.trunks, Logf: d.logf}
 }
 

modules/mesh-delivery-checker/cmd/mesh-delivery-checker/kept_test.go

@@ -37,8 +37,8 @@ func TestTheCheckerAnnouncesEveryStateItKeepsAndOwedReadable(t *testing.T) { //
 	if !equal(manifest, announced) {
 		t.Errorf("announced %v, the manifest keeps %v", announced, manifest)
 	}
-	// kept is read by the Go build module for a check ask (issue 1887 design limit 1).
-	if want := []string{"kept", "owed", "previews", "verdicts"}; !equal(readable, want) {
+	// kept is read by the Go build module for a check ask (issue 1887 design limit 1); tries by the delivery view (build_usage).
+	if want := []string{"kept", "owed", "previews", "tries", "verdicts"}; !equal(readable, want) {
 		t.Errorf("readable %v, want %v", readable, want)
 	}
 }

modules/mesh-delivery-checker/cmd/mesh-delivery-checker/lazyturns.go

@@ -0,0 +1,50 @@
+package main
+
+import (
+	"sync"
+
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+
+	"mesh-delivery-checker/internal/check"
+)
+
+// lazyTurns is the gate's merge turns as the checker reads them (novox/hq ADR 0548 §3), opened when the gate's bucket is
+// there: before each claim it is opened again until it is, so a checker that started before the gate made the bucket holds
+// checks from the gate's first turn on, with no timer and no restart. Until then it holds nothing, and says so once, loudly,
+// and once again when it opens.
+type lazyTurns struct {
+	turns *check.Turns
+	open  func() error
+	logf  func(format string, args ...any)
+
+	mu     sync.Mutex
+	opened bool
+	said   bool
+}
+
+// ensure opens the bucket once it is there; a failure is said once.
+func (l *lazyTurns) ensure() {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	if l.opened || l.open == nil {
+		return
+	}
+	if err := l.open(); err != nil {
+		if !l.said {
+			l.said = true
+			l.logf("NO MERGE TURN HOLDS A CHECK: the gate's bucket %s cannot be read (%v); every check is claimed as if no approved merge waited, "+
+				"and the bucket is opened again before each claim until it is there", delivery.TurnsBucket, err)
+		}
+		return
+	}
+	l.opened = true
+	if l.said {
+		l.logf("the gate's merge turns are read from %s from now on: an approved merge's turn holds checks off its repositories again", delivery.TurnsBucket)
+	}
+}
+
+// Holding opens the bucket when it is not yet, then answers what the turns hold.
+func (l *lazyTurns) Holding(repositories []string, heads string) (string, delivery.TurnWait, bool) {
+	l.ensure()
+	return l.turns.Holding(repositories, heads)
+}

modules/mesh-delivery-checker/cmd/mesh-delivery-checker/main.go

@@ -7,12 +7,7 @@ package main
 
 import (
 	"context"
-	"crypto/sha256"
-	"crypto/tls"
-	"crypto/x509"
-	"encoding/hex"
 	"encoding/json"
-	"errors"
 	"fmt"
 	"io"
 	"log"
@@ -36,7 +31,7 @@ import (
 // eventSubject is the subject of an event of the checker's stream checks (the bus names the stream CHECKS): the indexer's
 // watch of the previews bucket and the forge bridge's watch of the owed bucket are woken by them.
 func eventSubject(event string) string {
-	return "mesh.stream." + delivery.CheckerModule + ".event." + event
+	return process.ModuleStreamSubject(delivery.CheckerModule, event)
 }
 
 const (
@@ -53,50 +48,6 @@ func main() {
 	}
 }
 
-// credential is the broker file the controller issues to the module: JSON of the bus address, the certificate
-// fingerprint to pin, the principal and its password (as the indexer reads it; issue 1242 moves this into the SDK).
-type credential struct {
-	URL         string `json:"url"`
-	Fingerprint string `json:"fingerprint"`
-	Node        string `json:"node"`
-	Module      string `json:"module"`
-	User        string `json:"user"`
-	Password    string `json:"password"`
-}
-
-func readCredential(path string) (credential, error) {
-	raw, err := os.ReadFile(path)
-	if err != nil {
-		return credential{}, err
-	}
-	var c credential
-	if err := json.Unmarshal(raw, &c); err != nil {
-		return credential{}, fmt.Errorf("the broker credential is not one: %w", err)
-	}
-	if c.URL == "" || c.User == "" {
-		return credential{}, errors.New("the broker credential names no bus address or user")
-	}
-	return c, nil
-}
-
-// pinned accepts exactly the certificate with this SHA-256 and no other.
-func pinned(want string) *tls.Config {
-	return &tls.Config{
-		InsecureSkipVerify: true, //nolint:gosec // replaced by the pin below, which is stricter
-		MinVersion:         tls.VersionTLS12,
-		VerifyPeerCertificate: func(rawCerts [][]byte, _ [][]*x509.Certificate) error {
-			if len(rawCerts) == 0 {
-				return errors.New("the bus presented no certificate")
-			}
-			sum := sha256.Sum256(rawCerts[0])
-			if got := "sha256:" + hex.EncodeToString(sum[:]); got != want {
-				return fmt.Errorf("the bus presented a certificate this mesh does not know (%.23s…)", got)
-			}
-			return nil
-		},
-	}
-}
-
 // durationEnv reads a duration setting from the environment, def when it is not set.
 func durationEnv(getenv func(string) string, name string, def time.Duration) (time.Duration, error) {
 	v := strings.TrimSpace(getenv(name))
@@ -112,46 +63,33 @@ func durationEnv(getenv func(string) string, name string, def time.Duration) (ti
 
 // run is the program: it returns when ctx ends or the bus cannot be used.
 // keptStates is every state the checker keeps and which others may read (ADR 0495 §2-§3): owed by the forge module,
-// which writes mesh/check from it (ADR 0521), and by the forge bridge; previews by the indexer; verdicts by the gate.
+// which writes mesh/check from it (ADR 0521), and by the forge bridge; previews by the indexer; verdicts by the gate; tries by the delivery view.
 var keptStates = []announce.State{
 	// The kept verdicts are read by the Go build module, which takes them for a check ask's unchanged packages (issue 1887's
 	// design limit 1); the checker alone writes them (ADR 0444 clause 5).
+	// Whether DEAD_LETTERS is heard (issue 734): read by the checker's own status tool alone.
+	{Name: "hearing"},
+	// The asks each running check put (check.AsksState): read by the checker's own checker_ask_again alone.
+	{Name: "asks"},
 	{Name: "kept", Readable: true},
 	{Name: "owed", Readable: true},
 	{Name: "previews", Readable: true},
-	{Name: "tries"},
+	// The tries are read by the delivery view, which tells a try's asks from a candidate's by the asks each names (build_usage).
+	{Name: "tries", Readable: true},
 	{Name: "verdicts", Readable: true},
 }
 
 func run(ctx context.Context, getenv func(string) string, logOut io.Writer) error {
 	logger := log.New(logOut, "mesh-delivery-checker: ", log.LstdFlags)
-	path := strings.TrimSpace(getenv("MESH_BROKER_FILE"))
-	if path == "" {
-		return errors.New("MESH_BROKER_FILE is not set, so there is no credential to hear the bus with")
-	}
-	cred, err := readCredential(path)
+	cred, err := process.ReadBrokerAccount(getenv)
 	if err != nil {
 		return err
 	}
-	opts := []nats.Option{
-		nats.Name(cred.Node + "." + cred.Module),
-		nats.UserInfo(cred.User, cred.Password),
-		nats.CustomInboxPrefix("_INBOX." + cred.User),
-		nats.MaxReconnects(-1),
-		nats.RetryOnFailedConnect(true),
-	}
-	if strings.TrimSpace(cred.Fingerprint) != "" {
-		opts = append(opts, nats.Secure(pinned(cred.Fingerprint)))
-	}
-	conn, err := nats.Connect(cred.URL, opts...)
+	conn, js, err := cred.Dial()
 	if err != nil {
-		return fmt.Errorf("connecting to the bus: %w", err)
+		return err
 	}
 	defer conn.Close()
-	js, err := jetstream.New(conn)
-	if err != nil {
-		return err
-	}
 	// Its own states, the candidates it checks, and the modules and manifests that say which build modules judge a repository:
 	// a check without one of them would be wrong or unwritten, so each stops the start, naming its grant (issue 1945).
 	buckets := map[string]jetstream.KeyValue{}
@@ -163,11 +101,7 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 	}
 	// Calls to the build modules go out as this module's own account, naming the machine (mesh-sdk process.CallOn); the
 	// buckets are read and written on the connection above.
-	account, err := process.ReadAccount(path)
-	if err != nil {
-		return err
-	}
-	caller, err := process.Connect(account, nats.Name(cred.Node+"."+cred.Module+".calls"), nats.RetryOnFailedConnect(true))
+	caller, err := process.Connect(cred, nats.Name(cred.Node+"."+cred.Module+".calls"), nats.RetryOnFailedConnect(true))
 	if err != nil {
 		return err
 	}
@@ -186,6 +120,10 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 	if err != nil {
 		return err
 	}
+	settleWindow, err := durationEnv(getenv, "MESH_CHECKER_SETTLE", check.DefaultSettle)
+	if err != nil {
+		return err
+	}
 	link := strings.TrimSpace(getenv("MESH_CHECKER_LINK"))
 	if link == "" {
 		link = defaultLink
@@ -193,16 +131,37 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 	tools := &buildrun.ToolchainSet{}
 	presence := &buildrun.PresenceSet{}
 	trunks := &check.Trunks{}
+	turns := &check.Turns{}
+	lazy := &lazyTurns{turns: turns, logf: logger.Printf}
 	// A check is one ask per pull request and build module on the build seats' check stream, pulled by a build node with a
 	// free slot (novox/hq ADR 0525 §1, §3): the checker chooses no node and starts no step.
 	asks := buildrun.JetStreamAsks{JS: js}
+	// The asks the build seats gave up on (issue 734): heard from DEAD_LETTERS, each ends the step its asker waits for.
+	// Heard in the background, and again at a reconnect or an ask while it is not; whether it is heard is kept in the
+	// state hearing, which checker_status says (dead_letters).
+	dead := &buildrun.DeadLetters{}
+	// The state may not be on the bus yet when a delivery started the checker (the grants part creates it, issue 1790): it
+	// is bound when the bus says it was created, and the latest hearing is written then.
+	hearingKV := process.AwaitBucket(ctx, js, conn, check.HearingBucket, "checker_status cannot say whether DEAD_LETTERS is heard", logger.Printf)
+	hearing := buildrun.NewDeadLetterHearing(ctx, buildrun.JetStreamDeadLetters{JS: js}, []string{delivery.AskGo, delivery.AskNode}, dead,
+		logger.Printf, buildrun.SayHearing(ctx, hearingKV, logger.Printf))
+	defer hearing.Stop()
+	// Each ask's step is heard by its own watch and, at every step end of its build module and every reconnect, read
+	// (buildrun.HearEnds): a watch that goes deaf loses no end (the lost check of 2026-10-28).
+	heard := buildrun.HearEnds(ctx, asks, asks, []string{buildrun.GoBuildModule, buildrun.NodeBuildModule}, logger.Printf)
+	conn.SetReconnectHandler(func(*nats.Conn) { hearing.Again(); heard.Nudge("") })
+	waiter := buildrun.LostAskWaiter{Inner: heard, Dead: dead, Hearing: hearing}
+	asksKV := process.AwaitBucket(ctx, js, conn, check.AsksBucket, "checker_ask_again refuses every check, as it cannot tell whether its ask waits in a stream", logger.Printf)
 	ch := &check.Checker{
+		Asks:     awaitedKV{asksKV},
 		Verdicts: kvStore{buckets[delivery.CheckerVerdictsBucket]},
 		Owed:     kvStore{buckets[delivery.CheckerOwedBucket]},
 		Trunks:   trunks,
+		Turns:    lazy,
 		Bound:    checkBound,
 		Link:     link,
 		Logf:     logger.Printf,
+		Settle:   settleWindow,
 	}
 	// The builder's builds say how the candidates' fingerprints stand (issue 1684); where its bucket is not there yet the line
 	// says nothing of the builds, until the checker starts again.
@@ -228,7 +187,7 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 		return cw, nil
 	}}
 	// The tries (ADR 0501 §5) are judged by the same judge, held by the same deliveries.
-	tryer := &check.Tryer{Tries: kvStore{buckets[check.TriesBucket]}, Bound: checkBound, Logf: logger.Printf}
+	tryer := &check.Tryer{Tries: kvStore{buckets[check.TriesBucket]}, Bound: checkBound, NotTaken: stepBound, Logf: logger.Printf}
 	announce := func(ctx context.Context, event, key string) {
 		body, _ := json.Marshal(map[string]string{"key": key})
 		if _, err := js.Publish(ctx, eventSubject(event), body); err != nil {
@@ -236,22 +195,24 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 		}
 	}
 	repos := &repoModules{manifests: kvStore{buckets[delivery.ManifestsBucket]}, logf: logger.Printf}
+	ch.Runs = repos // the node-engine a check reads beside at its running commit (ADR 0548 §6)
 	ch.Judge = newJudge(judgeDeps{
-		asks: buildrun.Asker{Publisher: asks, Waiter: asks, Bound: stepBound}, tools: tools, trunks: trunks,
+		asks: buildrun.Asker{Publisher: asks, Waiter: waiter, Bound: stepBound}, tools: tools, trunks: trunks,
 		kept: kvStore{buckets[delivery.CheckerKeptBucket]}, previews: kvStore{buckets[delivery.PreviewsBucket]},
 		repos: repos, builds: builds, forge: forgeReads{call: caller.Call}, logf: logger.Printf,
 		announce: announce, compositions: compositions,
+		nodes: openNodeNames(ctx, js, logger.Printf),
 	})
 	ch.Announce = announce
 	tryer.Judge = ch.Judge
 
 	// The toolchains first, so a check that starts from the first candidate finds the nodes.
 	watch := newToolchainWatch(ctx, js, tools, ch.NodesChanged, logger)
-	// Only the toolchain reports of nodes the build module is assigned to count (issue 1940): the controller's
-	// assignments are settled first, so the toolchains settle through the gate already knowing them.
-	gate := newToolchainGate([]string{buildrun.GoBuildModule, buildrun.NodeBuildModule}, tools.Put, logger.Printf)
+	// Only the toolchain reports of nodes the catalogue places the build module on count (issue 1940, ADR 0549 §3): the
+	// placement is settled first, so the toolchains settle through the gate already knowing it.
+	gate := buildrun.NewToolchainGate([]string{buildrun.GoBuildModule, buildrun.NodeBuildModule}, tools.Put, logger.Printf)
 	watch.put = gate.Toolchain
-	assignErrs, err := watchAssignments(ctx, js, gate, ch.NodesChanged, logger)
+	placementErrs, err := buildrun.FollowPlacement(ctx, js, gate, ch.NodesChanged, logger.Printf)
 	if err != nil {
 		return err
 	}
@@ -263,13 +224,12 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 	// module.
 	for _, module := range []string{buildrun.GoBuildModule, buildrun.NodeBuildModule} {
 		stream := toolchainStreams[module]
-		cons, err := js.Consumer(ctx, stream, cred.Node+"_"+cred.Module)
+		cons, err := cred.EventConsumer(ctx, js, stream)
 		if err != nil {
 			logger.Printf("the consumer %s_%s on %s does not exist yet, so %s's reports are not heard until the checker starts again: %v", cred.Node, cred.Module, stream, module, err)
 			continue
 		}
-		cc, err := cons.Consume(func(m jetstream.Msg) { watch.Reported(m) },
-			jetstream.ConsumeErrHandler(func(_ jetstream.ConsumeContext, err error) { logger.Printf("hearing the bus: %v", err) }))
+		cc, err := process.HearEvents(cons, func(m jetstream.Msg) { watch.Reported(m) }, logger.Printf)
 		if err != nil {
 			return err
 		}
@@ -313,13 +273,42 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 			}()
 		}
 	}
+	// The gate's merge turns (novox/hq ADR 0548 §3): no check is claimed of a repository an approved merge waits on, and the
+	// delete of its turn claims it. Read before the candidates, so no check starts past a turn written before this start.
+	// Where the gate's bucket is not there yet it is read as empty, and opened again before each claim until it is there
+	// (lazyTurns), so a gate delivered after the checker started holds checks from its first turn on.
+	lazy.open = func() error {
+		kv, err := js.KeyValue(ctx, delivery.TurnsBucket)
+		if err != nil {
+			return err
+		}
+		tw, err := settle(ctx, kv, func(e jetstream.KeyValueEntry) { turns.Put(e.Key(), e.Value(), !opOf(e)) })
+		if err != nil {
+			return err
+		}
+		go func() {
+			errs <- follow(ctx, tw, func(e jetstream.KeyValueEntry) {
+				if turns.Put(e.Key(), e.Value(), !opOf(e)) {
+					ch.Reconsider(ctx) // a turn went or changed: a check it held is claimed now
+				}
+			})
+		}()
+		return nil
+	}
+	lazy.ensure()
 	// The modules say which repository holds a TypeScript module, so the Node build module judges it too.
 	mw, err := settle(ctx, buckets[delivery.ModulesBucket], func(e jetstream.KeyValueEntry) { repos.Put(ctx, e.Key(), e.Value(), !opOf(e)) })
 	if err != nil {
 		return err
 	}
 	go func() {
-		errs <- follow(ctx, mw, func(e jetstream.KeyValueEntry) { repos.Put(ctx, e.Key(), e.Value(), !opOf(e)) })
+		errs <- follow(ctx, mw, func(e jetstream.KeyValueEntry) {
+			before := repos.CommitOf(check.NodeEngineModule)
+			repos.Put(ctx, e.Key(), e.Value(), !opOf(e))
+			if after := repos.CommitOf(check.NodeEngineModule); after != before {
+				ch.TrunkMoved(ctx) // the node-engine the mesh runs moved: a verdict that read it beside is carried (ADR 0548 §6)
+			}
+		})
 	}()
 	each := func(e jetstream.KeyValueEntry) {
 		if opOf(e) {
@@ -349,6 +338,21 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 			}
 		})
 	}()
+	// The checker's own verdicts, updates only, in one watch: one checker_ask_again wrote asks its check again
+	// (Checker.VerdictWritten); a deleted key of heads a candidate holds is judged again (Checker.VerdictDeleted, issue 1733).
+	vw, err := buckets[delivery.CheckerVerdictsBucket].WatchAll(ctx, jetstream.UpdatesOnly())
+	if err != nil {
+		return fmt.Errorf("the checker's verdicts cannot be watched, so no check can be asked again by hand and a deleted verdict would never be written again: %w", err)
+	}
+	go func() {
+		errs <- follow(ctx, vw, func(e jetstream.KeyValueEntry) {
+			if opOf(e) {
+				ch.VerdictWritten(ctx, e.Key(), e.Value())
+			} else {
+				ch.VerdictDeleted(ctx, e.Key())
+			}
+		})
+	}()
 	logger.Printf("started on %s", cred.Node)
 	go func() { errs <- follow(ctx, w, each) }()
 	select {
@@ -358,7 +362,7 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 		return nil
 	case err := <-errs:
 		return err
-	case err := <-assignErrs:
+	case err := <-placementErrs:
 		return err
 	case err := <-watch.errs:
 		return err

modules/mesh-delivery-checker/cmd/mesh-delivery-checker/nodes_test.go

@@ -7,7 +7,8 @@ import (
 )
 
 // 1912: with checks as asks on the build seats' streams, the stream redelivers a lost node's ask (ADR 0525 §6), so the
-// checker program opens no node-engine have to start again a check that failed for want of a node.
+// checker program watches no node-engine have to start again a check that failed for want of a node. It reads the have's
+// keys only for the nodes' names at each ask (judge.go, novox/hq ADR 0567 §12).
 func TestTheCheckerWatchesNoHave(t *testing.T) {
 	raw, err := os.ReadFile("main.go")
 	if err != nil {

modules/mesh-delivery-checker/cmd/mesh-delivery-checker/refused_test.go

@@ -0,0 +1,62 @@
+package main
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"log"
+	"strings"
+	"testing"
+
+	"git.novox.be/novox/mesh-sdk/go/process"
+
+	"github.com/nats-io/nats.go/jetstream"
+
+	"git.novox.be/novox/mesh-sdk/go/delivery/buildrun"
+)
+
+// 1945 (a part exits at start for a bucket it works without): a bus that refuses every toolchains bucket leaves the
+// watch unstarted and the part running, said; a refused bucket it cannot work without is an error naming the bucket and
+// its grant. The gate over the seat's placement, and its refusal, are mesh-sdk's (buildrun.ToolchainGate,
+// issue 774).
+func TestARefusedBucketIsSaidAndThePartGoesOn(t *testing.T) {
+	set := &buildrun.ToolchainSet{}
+	var logs bytes.Buffer
+	logger := log.New(&logs, "", 0)
+	refused := refusingBus{err: errors.New("nats: permissions violation for publish to $JS.API.CONSUMER.CREATE.KV_mesh-build-node_toolchains")}
+	if err := newToolchainWatch(context.Background(), refusingBus{refuseOpen: true, err: refused.err}, set, func(context.Context) {}, logger).start(); err != nil {
+		t.Errorf("a refused toolchains bucket stopped the start: %v", err)
+	}
+	if !strings.Contains(logs.String(), "cannot be read") {
+		t.Errorf("the refusals were not said: %q", logs.String())
+	}
+	if _, err := process.EssentialBucket(context.Background(), refusingBus{refuseOpen: true, err: refused.err}, "checker", "mesh-delivery-indexer_modules", "work"); err == nil ||
+		!strings.Contains(err.Error(), "grant of mesh-delivery-indexer_modules") {
+		t.Errorf("a refused bucket the part needs: %v, want an error naming its grant", err)
+	}
+}
+
+// refusingBus is a bus that refuses: every open (refuseOpen), or every watch of a bucket it opens, with err.
+type refusingBus struct {
+	refuseOpen bool
+	err        error
+}
+
+func (r refusingBus) KeyValue(context.Context, string) (jetstream.KeyValue, error) {
+	if r.refuseOpen {
+		return nil, r.err
+	}
+	return refusedWatch{err: r.err}, nil
+}
+
+type refusedWatch struct {
+	jetstream.KeyValue
+	err error
+}
+
+func (r refusedWatch) WatchAll(context.Context, ...jetstream.WatchOpt) (jetstream.KeyWatcher, error) {
+	return nil, r.err
+}
+func (r refusedWatch) Watch(context.Context, string, ...jetstream.WatchOpt) (jetstream.KeyWatcher, error) {
+	return nil, r.err
+}

modules/mesh-delivery-checker/cmd/mesh-delivery-checker/standing.go

@@ -1,211 +0,0 @@
-package main
-
-// This file is the same in mesh-delivery-indexer, mesh-delivery-builder and mesh-delivery-checker (issue 1940): it moves
-// to mesh-sdk go/delivery/buildrun once mesh-sdk can be delivered again, since a change of mesh-sdk waits on the very
-// toolchain agreement this file repairs.
-
-import (
-	"context"
-	"encoding/json"
-	"fmt"
-	"log"
-	"maps"
-	"slices"
-	"strings"
-	"sync"
-	"time"
-
-	"github.com/nats-io/nats.go/jetstream"
-
-	"git.novox.be/novox/mesh-sdk/go/delivery"
-	"git.novox.be/novox/mesh-sdk/go/provider"
-)
-
-// A build module writes <node>.<language> of its toolchains state on every node it runs on, and nothing deletes the key
-// when the module is unassigned from a node: the controller writes no module's state, and the module is gone. A report of
-// a node the build module no longer runs on is therefore not a builder (issue 1940: mesh-build-node unassigned from ace
-// on 2026-10-23 left ace.typescript at v26.12.0, and every Node fingerprint said "builders disagree").
-//
-// toolchainGate stands between the toolchains buckets and what takes their entries in (the indexer's PutToolchain, a
-// buildrun.ToolchainSet): an entry is passed on only while the controller's assignments (mesh-controller_assignments,
-// key <node>.<module>) hold an open assignment of its build module on its node, and only once it was written since that
-// assignment; it is passed on as deleted otherwise, said once, and passed on when its node writes it again. A report
-// written before the assignment is the one an earlier run of the module left (issue 1940, 2026-10-25 20:56: mesh-build-node
-// assigned to ace again brought ace.typescript v26.12.0 of 2026-10-23 back into the agreement, before the module ran
-// there, and the controller's take-in refused every module "builders disagree"). Until the assignments are settled (or where they cannot
-// be read) every entry is passed on, as before. Builders that run and report different versions still disagree: that
-// refusal is the guard of novox/hq ADR 0465, and it stays.
-type toolchainGate struct {
-	mu       sync.Mutex
-	modules  map[string]bool                                           // the build modules whose toolchains pass the gate
-	forward  func(module, key string, value []byte, deleted bool) bool // answers whether it changed what it holds
-	logf     func(format string, a ...any)
-	known    bool                         // the assignments are settled
-	standing map[string]time.Time         // <node>.<module> with an open assignment -> since when it stands
-	raw      map[string]map[string][]byte // module -> toolchains key -> value, as the bucket holds it
-	left     map[string]string            // <module>/<key> -> why it was said left out, so each reason is said once
-}
-
-func newToolchainGate(modules []string, forward func(module, key string, value []byte, deleted bool) bool, logf func(string, ...any)) *toolchainGate {
-	g := &toolchainGate{modules: map[string]bool{}, forward: forward, logf: logf, standing: map[string]time.Time{},
-		raw: map[string]map[string][]byte{}, left: map[string]string{}}
-	for _, m := range modules {
-		g.modules[m] = true
-	}
-	return g
-}
-
-// Toolchain takes one change of a build module's toolchains bucket in and answers whether what it passed on changed.
-func (g *toolchainGate) Toolchain(module, key string, value []byte, deleted bool) bool {
-	g.mu.Lock()
-	defer g.mu.Unlock()
-	if g.raw[module] == nil {
-		g.raw[module] = map[string][]byte{}
-	}
-	if deleted {
-		delete(g.raw[module], key)
-	} else {
-		g.raw[module][key] = value
-	}
-	return g.pass(module, key)
-}
-
-// Assignment takes one change of the controller's assignments in (at is when the bus wrote that revision) and answers
-// whether what it passed on changed.
-func (g *toolchainGate) Assignment(key string, value []byte, deleted bool, at time.Time) bool {
-	node, module, ok := strings.Cut(key, ".")
-	if !ok || !g.modules[module] {
-		return false
-	}
-	assigned, open := openAssignment(value)
-	open = open && !deleted
-	g.mu.Lock()
-	defer g.mu.Unlock()
-	was, stood := g.standing[key]
-	since := assigned
-	if since.IsZero() {
-		// A value with no time of its own (an assignment a module pulled in) stands since the revision that opened it.
-		since = at
-		if stood {
-			since = was
-		}
-	}
-	if open == stood && (!open || since.Equal(was)) {
-		return false
-	}
-	if open {
-		g.standing[key] = since
-	} else {
-		delete(g.standing, key)
-	}
-	if !g.known {
-		return false
-	}
-	changed := false
-	for _, k := range slices.Sorted(maps.Keys(g.raw[module])) {
-		if n, _, err := delivery.ParseToolchainKey(k); err == nil && n == node {
-			changed = g.pass(module, k) || changed
-		}
-	}
-	return changed
-}
-
-// Settled says the assignments are read: from now on only the reports of assigned nodes pass. It answers whether what it
-// passed on changed.
-func (g *toolchainGate) Settled() bool {
-	g.mu.Lock()
-	defer g.mu.Unlock()
-	g.known = true
-	changed := false
-	for _, module := range slices.Sorted(maps.Keys(g.raw)) {
-		for _, k := range slices.Sorted(maps.Keys(g.raw[module])) {
-			changed = g.pass(module, k) || changed
-		}
-	}
-	return changed
-}
-
-// pass hands one key on as it stands: its value when its node is assigned and wrote it since (or the assignments are not
-// known), deleted otherwise. The caller holds mu.
-func (g *toolchainGate) pass(module, key string) bool {
-	value, held := g.raw[module][key]
-	if !held {
-		return g.forward(module, key, nil, true)
-	}
-	node, _, err := delivery.ParseToolchainKey(key)
-	why := ""
-	if err == nil && g.known {
-		why = g.leftOut(module, node, value)
-	}
-	if why == "" {
-		delete(g.left, module+"/"+key)
-		return g.forward(module, key, value, false)
-	}
-	if g.left[module+"/"+key] != why {
-		g.left[module+"/"+key] = why
-		g.logf("%s.%s is left out of the agreed toolchain: %s (issue 1940)", delivery.ToolchainsBucket(module), key, why)
-	}
-	return g.forward(module, key, nil, true)
-}
-
-// leftOut is why a node's report is no builder's, or empty when it counts: its node has no open assignment of the module,
-// or the report was written before that assignment. A value that is no toolchain is passed on for its reader to refuse.
-// The caller holds mu.
-func (g *toolchainGate) leftOut(module, node string, value []byte) string {
-	since, open := g.standing[node+"."+module]
-	if !open {
-		return fmt.Sprintf("%s has no assignment on %s, so it is no builder", module, node)
-	}
-	tc, err := delivery.DecodeToolchain(value)
-	if err == nil && tc.At.Before(since) {
-		return fmt.Sprintf("it was written at %s, before %s's assignment on %s at %s: it counts once %s writes it again",
-			tc.At.UTC().Format(time.RFC3339), module, node, since.UTC().Format(time.RFC3339), node)
-	}
-	return ""
-}
-
-// openAssignment is whether a value of the controller's assignments holds an assignment that stands (one that has not
-// ended and has no state: a pending one is not on the machine yet; mesh-controller internal/chain Assignment), and when
-// it was assigned, zero where the value does not say.
-func openAssignment(value []byte) (time.Time, bool) {
-	var a struct {
-		Assigned time.Time `json:"assigned"`
-		Ended    time.Time `json:"ended"`
-		State    string    `json:"state"`
-	}
-	if json.Unmarshal(value, &a) != nil {
-		return time.Time{}, false
-	}
-	return a.Assigned, a.Ended.IsZero() && a.State == ""
-}
-
-// watchAssignments settles the controller's assignments into the gate, says them settled, and follows them; changed is
-// told whenever what the gate passes on changed. Where the bucket cannot be read (not there, or this module may not read
-// it) it says so and the gate passes every report on, as before; an error of the watch after that ends on the channel.
-func watchAssignments(ctx context.Context, js bucketOpener, gate *toolchainGate, changed func(context.Context), logger *log.Logger) (<-chan error, error) {
-	errs := make(chan error, 1)
-	kv, err := js.KeyValue(ctx, provider.AssignmentsBucket)
-	if err != nil {
-		// Not fatal: an indexer, builder or checker that stops for it stops every delivery (a grant comes with a delivery).
-		logger.Printf("the bucket %s cannot be read, so every node's toolchain report counts, an unassigned build node's too (issue 1940): %v", provider.AssignmentsBucket, err)
-		return errs, nil
-	}
-	each := func(e jetstream.KeyValueEntry) { gate.Assignment(e.Key(), e.Value(), !opOf(e), e.Created()) }
-	w, err := settle(ctx, kv, each)
-	if err != nil {
-		// Not fatal either (issue 1945): a watch the bus refuses is the same missing grant as a refused read.
-		logger.Printf("the bucket %s cannot be watched, so every node's toolchain report counts, an unassigned build node's too (issue 1940): %v", provider.AssignmentsBucket, err)
-		return errs, nil
-	}
-	if gate.Settled() {
-		changed(ctx)
-	}
-	go func() {
-		errs <- follow(ctx, w, func(e jetstream.KeyValueEntry) {
-			if gate.Assignment(e.Key(), e.Value(), !opOf(e), e.Created()) {
-				changed(ctx)
-			}
-		})
-	}()
-	return errs, nil
-}

modules/mesh-delivery-checker/cmd/mesh-delivery-checker/standing_test.go

@@ -1,218 +0,0 @@
-package main
-
-// The same in mesh-delivery-indexer, mesh-delivery-builder and mesh-delivery-checker, as standing.go is (issue 1940).
-
-import (
-	"bytes"
-	"context"
-	"errors"
-	"fmt"
-	"log"
-	"strings"
-	"testing"
-	"time"
-
-	"git.novox.be/novox/mesh-sdk/go/process"
-
-	"github.com/nats-io/nats.go/jetstream"
-
-	"git.novox.be/novox/mesh-sdk/go/delivery"
-	"git.novox.be/novox/mesh-sdk/go/delivery/buildrun"
-)
-
-func gateReport(t *testing.T, node, version string) (string, []byte) {
-	t.Helper()
-	key, err := delivery.ToolchainKey(node, "typescript")
-	if err != nil {
-		t.Fatal(err)
-	}
-	value, err := delivery.EncodeToolchain(delivery.Toolchain{Language: "typescript", Version: version, Recipe: "f59571cf4be75adf", At: time.Unix(0, 0).UTC()})
-	if err != nil {
-		t.Fatal(err)
-	}
-	return key, value
-}
-
-func agreedOf(set *buildrun.ToolchainSet) (string, string) {
-	tc, none := delivery.AgreedToolchain(set.Entries("typescript"))
-	return tc.Version, none
-}
-
-// The live case of issue 1940: mesh-build-node was unassigned from ace, whose report stayed at v26.12.0 while the
-// three nodes it runs on report v26.12.1. Without the assignments every report counts (and they disagree); with them
-// ace's is left out and the three agree; assigned to ace again, its report counts again and the guard refuses again.
-func TestAnUnassignedBuildNodesReportIsNoBuilder(t *testing.T) {
-	set := &buildrun.ToolchainSet{}
-	var said []string
-	gate := newToolchainGate([]string{buildrun.GoBuildModule, buildrun.NodeBuildModule}, set.Put, func(f string, a ...any) { said = append(said, f) })
-	for node, version := range map[string]string{"ace": "v26.12.0", "g14": "v26.12.1", "novox": "v26.12.1", "shanks": "v26.12.1"} {
-		key, value := gateReport(t, node, version)
-		gate.Toolchain(buildrun.NodeBuildModule, key, value, false)
-	}
-	if _, none := agreedOf(set); !strings.HasPrefix(none, "builders disagree") {
-		t.Fatalf("before the assignments are read every report counts, so they disagree; got %q", none)
-	}
-	for _, node := range []string{"g14", "novox", "shanks"} {
-		gate.Assignment(node+"."+buildrun.NodeBuildModule, []byte(`{"node":"`+node+`","module":"mesh-build-node"}`), false, time.Time{})
-	}
-	gate.Assignment("ace.mesh-build-node", []byte(`{"node":"ace","module":"mesh-build-node","ended":"2026-10-23T08:00:00Z"}`), false, time.Time{})
-	gate.Assignment("ace.mesh-build-go", []byte(`{"node":"ace","module":"mesh-build-go"}`), false, time.Time{}) // another module's: no matter
-	if !gate.Settled() {
-		t.Fatal("settling the assignments left ace's report out, so what was passed on changed")
-	}
-	if v, none := agreedOf(set); v != "v26.12.1" || none != "" {
-		t.Fatalf("the assigned nodes agree on v26.12.1; got %q, %q", v, none)
-	}
-	if len(said) != 1 {
-		t.Fatalf("ace's report is said left out once; said %v", said)
-	}
-	// ace reports again while unassigned (an old value seen again): still left out.
-	key, value := gateReport(t, "ace", "v26.12.0")
-	if gate.Toolchain(buildrun.NodeBuildModule, key, value, false) {
-		t.Fatal("an unassigned node's report changed what was passed on")
-	}
-	// Assigned to ace again: its report counts, and the builders really disagree: the guard stays.
-	if !gate.Assignment("ace.mesh-build-node", []byte(`{"node":"ace","module":"mesh-build-node"}`), false, time.Time{}) {
-		t.Fatal("assigning ace again passed nothing on")
-	}
-	if _, none := agreedOf(set); !strings.HasPrefix(none, "builders disagree: v26.12.0 recipe f59571cf4be75adf on ace") {
-		t.Fatalf("builders that run different versions still disagree; got %q", none)
-	}
-	// The assignment's key deleted, or a pending one written: no assignment stands, and ace's report goes again.
-	if !gate.Assignment("ace.mesh-build-node", []byte(`{"node":"ace","module":"mesh-build-node","state":"pending"}`), false, time.Time{}) {
-		t.Fatal("a pending assignment is no assignment on the machine")
-	}
-	if v, none := agreedOf(set); v != "v26.12.1" || none != "" {
-		t.Fatalf("got %q, %q", v, none)
-	}
-	gate.Assignment("ace.mesh-build-node", nil, true, time.Time{})
-	if v, _ := agreedOf(set); v != "v26.12.1" {
-		t.Fatalf("got %q", v)
-	}
-	// A report deleted from the bucket goes whether its node is assigned or not.
-	key, _ = gateReport(t, "g14", "v26.12.1")
-	if !gate.Toolchain(buildrun.NodeBuildModule, key, nil, true) {
-		t.Fatal("deleting g14's report passed nothing on")
-	}
-	if n := len(set.Entries("typescript")); n != 2 {
-		t.Fatalf("novox and shanks are left; got %d entries", n)
-	}
-
-	// 1945 (a part exits at start for a bucket it works without): a bus that refuses the assignments' watch, or every
-	// toolchains bucket, leaves the watches unstarted and the part running, said; a refused bucket it cannot work without
-	// is an error naming the bucket and its grant.
-	var logs bytes.Buffer
-	logger := log.New(&logs, "", 0)
-	refused := refusingBus{err: errors.New("nats: permissions violation for publish to $JS.API.CONSUMER.CREATE.KV_mesh-controller_assignments")}
-	if _, err := watchAssignments(context.Background(), refused, newToolchainGate(nil, set.Put, t.Logf), func(context.Context) {}, logger); err != nil {
-		t.Errorf("a refused watch of the assignments stopped the start: %v", err)
-	}
-	if err := newToolchainWatch(context.Background(), refusingBus{refuseOpen: true, err: refused.err}, set, func(context.Context) {}, logger).start(); err != nil {
-		t.Errorf("a refused toolchains bucket stopped the start: %v", err)
-	}
-	if !strings.Contains(logs.String(), "cannot be watched") || !strings.Contains(logs.String(), "cannot be read") {
-		t.Errorf("the refusals were not said: %q", logs.String())
-	}
-	if _, err := process.EssentialBucket(context.Background(), refusingBus{refuseOpen: true, err: refused.err}, "checker", "mesh-delivery-indexer_modules", "work"); err == nil ||
-		!strings.Contains(err.Error(), "grant of mesh-delivery-indexer_modules") {
-		t.Errorf("a refused bucket the part needs: %v, want an error naming its grant", err)
-	}
-}
-
-// refusingBus is a bus that refuses: every open (refuseOpen), or every watch of a bucket it opens, with err.
-type refusingBus struct {
-	refuseOpen bool
-	err        error
-}
-
-func (r refusingBus) KeyValue(context.Context, string) (jetstream.KeyValue, error) {
-	if r.refuseOpen {
-		return nil, r.err
-	}
-	return refusedWatch{err: r.err}, nil
-}
-
-type refusedWatch struct {
-	jetstream.KeyValue
-	err error
-}
-
-func (r refusedWatch) WatchAll(context.Context, ...jetstream.WatchOpt) (jetstream.KeyWatcher, error) {
-	return nil, r.err
-}
-func (r refusedWatch) Watch(context.Context, string, ...jetstream.WatchOpt) (jetstream.KeyWatcher, error) {
-	return nil, r.err
-}
-
-// A build node's report counts from the first one it writes since its assignment: a newly assigned node that has not
-// reported changes nothing, and the report an earlier run left on the bus (issue 1940, 2026-10-25 20:56: ace.typescript
-// v26.12.0 of 2026-10-23 06:29, mesh-build-node assigned to ace again at 20:56:45) is left out, said once, until the node
-// writes it again. An assignment whose value names no time stands since the revision that opened it.
-func TestANewlyAssignedNodeCountsFromItsReport(t *testing.T) {
-	left := time.Date(2026, 10, 23, 6, 29, 18, 0, time.UTC)      // ace's report from its earlier run
-	assigned := time.Date(2026, 10, 25, 19, 56, 45, 0, time.UTC) // mesh-build-node assigned to ace again
-	report := func(t *testing.T, node, version string, at time.Time) (string, []byte) {
-		key, _ := gateReport(t, node, version)
-		value, err := delivery.EncodeToolchain(delivery.Toolchain{Language: "typescript", Version: version, Recipe: "f59571cf4be75adf", At: at})
-		if err != nil {
-			t.Fatal(err)
-		}
-		return key, value
-	}
-	for _, c := range []struct {
-		name       string
-		assignment string    // ace's assignment value
-		revision   time.Time // when the bus wrote it
-		at         time.Time // when ace wrote its report
-		counts     bool
-	}{
-		{"no report yet, then one", `{}`, time.Time{}, time.Now(), true},
-		{"a report left before the assignment", `{"node":"ace","module":"mesh-build-node","assigned":"2026-10-25T19:56:45Z"}`, assigned, left, false},
-		{"a report left before a value with no time", `{"node":"ace","module":"mesh-build-node"}`, assigned, left, false},
-		{"a report written since the assignment", `{"node":"ace","module":"mesh-build-node","assigned":"2026-10-25T19:56:45Z"}`, assigned, assigned.Add(30 * time.Second), true},
-	} {
-		t.Run(c.name, func(t *testing.T) {
-			set := &buildrun.ToolchainSet{}
-			var said []string
-			gate := newToolchainGate([]string{buildrun.NodeBuildModule}, set.Put, func(f string, a ...any) { said = append(said, fmt.Sprintf(f, a...)) })
-			for _, node := range []string{"g14", "novox", "shanks"} {
-				gate.Assignment(node+".mesh-build-node", []byte(`{}`), false, time.Time{})
-				key, value := gateReport(t, node, "v26.12.1")
-				gate.Toolchain(buildrun.NodeBuildModule, key, value, false)
-			}
-			gate.Settled()
-			if gate.Assignment("ace.mesh-build-node", []byte(c.assignment), false, c.revision) {
-				t.Fatal("an assignment with no report passed something on")
-			}
-			key, value := report(t, "ace", "v26.12.0", c.at)
-			if got := gate.Toolchain(buildrun.NodeBuildModule, key, value, false); got != c.counts {
-				t.Fatalf("ace's report passed on: %v, want %v", got, c.counts)
-			}
-			// A rewrite of the assignment that does not move it changes nothing, and nothing is said again.
-			if gate.Assignment("ace.mesh-build-node", []byte(c.assignment), false, c.revision.Add(time.Minute)) {
-				t.Fatal("the same assignment written again changed what was passed on")
-			}
-			v, none := agreedOf(set)
-			if c.counts {
-				if !strings.HasPrefix(none, "builders disagree: v26.12.0 recipe f59571cf4be75adf on ace") {
-					t.Fatalf("ace's own report counts and disagrees; got %q, %q", v, none)
-				}
-				return
-			}
-			if v != "v26.12.1" || none != "" {
-				t.Fatalf("ace's left report is no builder's, so g14, novox and shanks agree; got %q, %q", v, none)
-			}
-			if len(said) != 1 || !strings.Contains(said[0], "before mesh-build-node's assignment on ace at 2026-10-25T19:56:45Z") {
-				t.Fatalf("said %q, want once why ace's report is left out", said)
-			}
-			// ace writes its report again since it was assigned: it counts.
-			key, value = report(t, "ace", "v26.12.1", assigned.Add(time.Minute))
-			if !gate.Toolchain(buildrun.NodeBuildModule, key, value, false) {
-				t.Fatal("ace's new report was not passed on")
-			}
-			if n := len(set.Entries("typescript")); n != 4 {
-				t.Fatalf("four builders report; got %d", n)
-			}
-		})
-	}
-}

modules/mesh-delivery-checker/go.mod

@@ -3,7 +3,7 @@ module mesh-delivery-checker
 go 1.26.0
 
 require (
-	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261025211220-e0d1de047585
+	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261028205404-8eafc0c5ce3c
 	github.com/nats-io/nats-server/v2 v2.11.17
 	github.com/nats-io/nats.go v1.54.0
 )

modules/mesh-delivery-checker/go.sum

@@ -1,7 +1,5 @@
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261023213200-403a5d72ab93 h1:FAiFY2KBKEoZSH49OZTt7/zRBIQxyl5g/KhYrpggbN4=
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261023213200-403a5d72ab93/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261025211220-e0d1de047585 h1:7QoFH5qjXRpx5M4uPdYsVJ5qKl2082gq8n0lFxhoNIg=
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261025211220-e0d1de047585/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261028205404-8eafc0c5ce3c h1:hcqOCd5q3M0ZiEzB6MhwxT/AOKkm9gaskKqPcpkAAg8=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261028205404-8eafc0c5ce3c/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op h1:Z/MZK75wC/NSrkgqeNIa7jexam9uWzhLmFTSCPI/kn0=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op/go.mod h1:FQyySiasQQM8735Ddel3MRojmy4dA1IqCeyJ5jmPMbI=
 github.com/google/go-tpm v0.9.8 h1:slArAR9Ft+1ybZu0lBwpSmpwhRXaa85hWtMinMyRAWo=

modules/mesh-delivery-checker/internal/check/adr548_test.go

@@ -0,0 +1,355 @@
+package check
+
+import (
+	"context"
+	"strings"
+	"testing"
+	"time"
+
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+)
+
+// One check per delivery (novox/hq ADR 0548): the checker's part. A merge turn holds new checks off its repository (§3);
+// a trunk or sibling move never ends a running check and carries its verdict once it ended (§1, §5, §6); only a head git
+// refused gets a whole check after a move (§7); the line of a carried verdict says so (§8).
+
+// turnOf is a turn's value on a repository for a delivery of the heads hash.
+func turnOf(t testing.TB, repo, group, heads string) []byte {
+	t.Helper()
+	at := time.Date(2026, 10, 26, 9, 0, 0, 0, time.UTC)
+	data, err := delivery.EncodeTurn(delivery.Turn{Repository: repo, Waiting: []delivery.TurnWait{{Group: group, Heads: heads, Approved: at, Since: at}}})
+	if err != nil {
+		t.Fatal(err)
+	}
+	return data
+}
+
+func turnKey(t testing.TB, repo string) string {
+	t.Helper()
+	k, err := delivery.TurnsKey(repo)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return k
+}
+
+// waitFor polls a condition the checker's goroutines make true, failing after two seconds.
+func waitFor(t testing.TB, what string, ok func() bool) {
+	t.Helper()
+	for deadline := time.Now().Add(2 * time.Second); !ok(); time.Sleep(time.Millisecond) {
+		if time.Now().After(deadline) {
+			t.Fatalf("%s did not happen", what)
+		}
+	}
+}
+
+// pullWithFP is a pull request touching the module m at the fingerprint `src2:` and 64 times the hex digit d.
+func pullWithFP(repo string, number int, head string, d string) delivery.CandidatePull {
+	p := pullOf(repo, number, head)
+	p.Modules = []string{"m"}
+	p.Fps = map[string]delivery.CandidateModule{"m": {FP2: "src2:" + strings.Repeat(d, 64)}}
+	return p
+}
+
+func TestOneCheckPerDelivery(t *testing.T) {
+	ctx := context.Background()
+	for name, run := range map[string]func(t *testing.T){
+		// §3: no claim while a turn names one of its repositories; a claim on the turn's delete event.
+		"a turn on its repository holds a new check off until the turn goes": func(t *testing.T) {
+			j := passJudge()
+			r := newRig(t, j)
+			turns := &Turns{}
+			r.ch.Turns = turns
+			turns.Put(turnKey(t, repoA), turnOf(t, repoA, "fix/other", "0123456789ab"), false)
+			cand := candidateOf(t, "feat/x", pullOf(repoA, 7, head1))
+			r.ch.Candidate(ctx, "feat%2Fx", cand)
+			r.ch.Wait()
+			if j.count() != 0 || len(r.verdicts.vals) != 0 {
+				t.Fatalf("judged %d times with a turn on %s, verdicts %v", j.count(), repoA, r.verdicts.vals)
+			}
+			if held := r.ch.Held()[keyOf(t, "feat/x", cand)]; !strings.Contains(held, repoA) || !strings.Contains(held, "fix/other") {
+				t.Errorf("the hold is said as %q, want the turn's repository and group", held)
+			}
+			if !turns.Put(turnKey(t, repoA), nil, true) {
+				t.Fatal("the turn's delete changed nothing")
+			}
+			r.ch.Reconsider(ctx) // what the watch of turns does on the delete
+			r.ch.Wait()
+			if j.count() != 1 || r.verdict(t, keyOf(t, "feat/x", cand)).State != delivery.VerdictPass {
+				t.Errorf("judged %d times after the turn went, want once", j.count())
+			}
+		},
+		"a turn on another repository, or of its own heads, holds nothing": func(t *testing.T) {
+			j := passJudge()
+			r := newRig(t, j)
+			turns := &Turns{}
+			r.ch.Turns = turns
+			cand := candidateOf(t, "feat/x", pullOf(repoA, 7, head1))
+			c, _ := delivery.DecodeCandidate(cand)
+			turns.Put(turnKey(t, repoSDK), turnOf(t, repoSDK, "fix/other", "0123456789ab"), false)
+			turns.Put(turnKey(t, repoA), turnOf(t, repoA, "feat/x", GateHeads(c)), false)
+			r.ch.Candidate(ctx, "feat%2Fx", cand)
+			r.ch.Wait()
+			if j.count() != 1 {
+				t.Errorf("judged %d times, want once: the turns hold another repository and its own merge", j.count())
+			}
+		},
+		// §3, the race: a check claimed before the gate's turn is judged on the commit it read, never restarted.
+		"a check claimed before a turn was written runs to its verdict": func(t *testing.T) {
+			release, started := make(chan struct{}), make(chan struct{})
+			j := &judgeFunc{f: func(context.Context, *Case, int) (Outcome, error) {
+				close(started)
+				<-release
+				return Outcome{Verdict: passing()}, nil
+			}}
+			r := newRig(t, j)
+			turns := &Turns{}
+			r.ch.Turns = turns
+			cand := candidateOf(t, "feat/x", pullOf(repoA, 7, head1))
+			r.ch.Candidate(ctx, "feat%2Fx", cand)
+			<-started
+			turns.Put(turnKey(t, repoA), turnOf(t, repoA, "fix/other", "0123456789ab"), false)
+			r.ch.Reconsider(ctx)
+			close(release)
+			r.ch.Wait()
+			if j.count() != 1 || r.verdict(t, keyOf(t, "feat/x", cand)).State != delivery.VerdictPass {
+				t.Errorf("judged %d times; the running check is not ended by the turn", j.count())
+			}
+		},
+		// §1, §5: a trunk move during a running check calls the judge once, writes its verdict, keeps the status pending (a pass
+		// on an old trunk is never shown), then asks one carry, on the recheck stream, and no check.
+		"a trunk move during a check ends nothing and asks one carry after it": func(t *testing.T) {
+			var r *rig
+			var kinds []string
+			var from []map[string]string
+			judged := make(chan struct{})
+			j := &judgeFunc{f: func(ctx context.Context, c *Case, call int) (Outcome, error) {
+				kinds, from = append(kinds, c.Kind), append(from, c.CarriedFrom)
+				if call == 1 {
+					r.setTrunks(t, map[string]string{repoA: trunkA2, repoSDK: trunkS}) // the trunk moves while it runs
+					r.ch.TrunkMoved(ctx)                                               // as the watch of the source says it
+					close(judged)
+				} else if s := owedState(t, r, repoA, 7, head1); s != "pending" {
+					t.Errorf("the status during the carry is %q, want pending: the pass on the old trunk is never shown", s)
+				}
+				return Outcome{Verdict: passing()}, nil
+			}}
+			r = newRig(t, j)
+			cand := candidateOf(t, "feat/x", pullOf(repoA, 7, head1))
+			r.ch.Candidate(ctx, "feat%2Fx", cand)
+			<-judged
+			r.ch.Wait()
+			v := r.verdict(t, keyOf(t, "feat/x", cand))
+			if j.count() != 2 || kinds[0] != KindNew || kinds[1] != KindTrunk || from[0] != nil || from[1][repoA] != trunkA {
+				t.Fatalf("judged %d times as %v carried from %v; want a whole check, then one carry from %s", j.count(), kinds, from, trunkA[:12])
+			}
+			if v.State != delivery.VerdictPass || v.Trunk[repoA] != trunkA2 || v.CarriedFrom[repoA] != trunkA {
+				t.Errorf("the verdict is %s on %v carried from %v; want a pass on the new trunk carried from the old", v.State, v.Trunk, v.CarriedFrom)
+			}
+			if s := owedState(t, r, repoA, 7, head1); s != "success" {
+				t.Errorf("the status after the carry is %q, want success", s)
+			}
+			if r.verdicts.creates[keyOf(t, "feat/x", cand)] != 1 {
+				t.Error("the verdict key was made again: a carry rewrites it")
+			}
+		},
+		// §5: the composition is kept when no fingerprint of a module it composed changed, and runs again otherwise.
+		"a carry keeps a passed composition while the fingerprints stay the same": func(t *testing.T) {
+			var kept []bool
+			j := &judgeFunc{f: func(_ context.Context, c *Case, _ int) (Outcome, error) {
+				kept = append(kept, c.Composition != nil)
+				v := passing()
+				v.Composition = &delivery.Composition{State: delivery.CompositionPass, SDK: "v0.1.14-x", FPSet: c.FPSet}
+				return Outcome{Verdict: v}, nil
+			}}
+			r := newRig(t, j)
+			cand := candidateOf(t, "feat/x", pullWithFP(repoA, 7, head1, "a"))
+			r.ch.Candidate(ctx, "feat%2Fx", cand)
+			r.ch.Wait()
+			r.setTrunks(t, map[string]string{repoA: trunkA2, repoSDK: trunkS})
+			r.ch.TrunkMoved(ctx) // the indexer's fingerprints of the candidate stay the same
+			r.ch.Wait()
+			r.ch.Candidate(ctx, "feat%2Fx", candidateOf(t, "feat/x", pullWithFP(repoA, 7, head1, "b"))) // a fingerprint changed with the move
+			r.setTrunks(t, map[string]string{repoA: trunkA, repoSDK: trunkS})
+			r.ch.TrunkMoved(ctx)
+			r.ch.Wait()
+			if len(kept) != 3 || kept[0] || !kept[1] || kept[2] {
+				t.Errorf("the composition was kept in the checks %v; want composed, kept on the carry, composed again once a fingerprint changed", kept)
+			}
+		},
+		// §6: a sibling's move puts the verdict out of date, its status pending saying it is carried, and the carry's verdict
+		// names the sibling's old commit; the status follows the carry's verdict. Which packages run is the digest's (only
+		// those that name MESH_CHECK_BESIDE change with a sibling), the build module's part.
+		"a sibling's move is carried and the status follows the carry": func(t *testing.T) {
+			var r *rig
+			var from map[string]string
+			j := &judgeFunc{f: func(_ context.Context, c *Case, call int) (Outcome, error) {
+				if call == 2 {
+					from = c.CarriedFrom
+					if s := owedState(t, r, repoA, 7, head1); s != "pending" {
+						t.Errorf("the status during the sibling's carry is %q, want pending", s)
+					}
+				}
+				return Outcome{Verdict: passing(), Beside: map[string]string{catalogueRepository: r.trunks.Heads()[catalogueRepository]}}, nil
+			}}
+			r = newRig(t, j)
+			r.setTrunks(t, map[string]string{repoA: trunkA, repoSDK: trunkS, catalogueRepository: trunkS})
+			cand := candidateOf(t, "feat/x", pullOf(repoA, 7, head1))
+			r.ch.Candidate(ctx, "feat%2Fx", cand)
+			r.ch.Wait()
+			if b := r.verdict(t, keyOf(t, "feat/x", cand)).Beside; b[catalogueRepository] != trunkS {
+				t.Fatalf("the verdict names the siblings %v, want the catalogue at %s", b, trunkS[:12])
+			}
+			r.setTrunks(t, map[string]string{repoA: trunkA, repoSDK: trunkS, catalogueRepository: trunkS2})
+			r.ch.TrunkMoved(ctx)
+			r.ch.Wait()
+			v := r.verdict(t, keyOf(t, "feat/x", cand))
+			if j.count() != 2 || from[catalogueRepository] != trunkS || v.CarriedFrom[catalogueRepository] != trunkS || v.Beside[catalogueRepository] != trunkS2 {
+				t.Errorf("judged %d times, carried from %v, verdict beside %v carried from %v; want one carry over the catalogue's move", j.count(), from, v.Beside, v.CarriedFrom)
+			}
+			if s := owedState(t, r, repoA, 7, head1); s != "success" {
+				t.Errorf("the status after the carry is %q, want success", s)
+			}
+		},
+		// §7: a carry whose merge conflicts fails naming the files and asks no check; a later move onto which the head merges
+		// cleanly asks a whole check, not a carry.
+		"a carry git refuses fails naming the files, and the next move asks a whole check": func(t *testing.T) {
+			var kinds []string
+			var from []map[string]string
+			j := &judgeFunc{f: func(_ context.Context, c *Case, call int) (Outcome, error) {
+				kinds, from = append(kinds, c.Kind), append(from, c.CarriedFrom)
+				if call == 2 {
+					return Outcome{Verdict: delivery.Verdict{State: delivery.VerdictFail, Failed: delivery.FailedFirst{Machine: "ace",
+						Words: repoA + "#7 " + ConflictWords + "go.mod"}}}, nil
+				}
+				return Outcome{Verdict: passing()}, nil
+			}}
+			r := newRig(t, j)
+			cand := candidateOf(t, "feat/x", pullOf(repoA, 7, head1))
+			r.ch.Candidate(ctx, "feat%2Fx", cand)
+			r.ch.Wait()
+			r.setTrunks(t, map[string]string{repoA: trunkA2, repoSDK: trunkS})
+			r.ch.TrunkMoved(ctx)
+			r.ch.Wait()
+			r.ch.Reconsider(ctx) // anything else that looks again asks nothing of a conflict
+			r.ch.Wait()
+			if v := r.verdict(t, keyOf(t, "feat/x", cand)); j.count() != 2 || !IsConflictFailure(v) || !strings.Contains(v.Failed.Words, "go.mod") {
+				t.Fatalf("judged %d times, verdict %+v; want the carry failed naming go.mod and nothing asked after it", j.count(), v.Failed)
+			}
+			r.setTrunks(t, map[string]string{repoA: trunkA, repoSDK: trunkS})
+			r.ch.TrunkMoved(ctx)
+			r.ch.Wait()
+			if j.count() != 3 || kinds[1] != KindTrunk || from[1] == nil || kinds[2] != KindNew || from[2] != nil {
+				t.Errorf("checks %v carried from %v; want a whole check, a carry, then a whole check after the conflict", kinds, from)
+			}
+		},
+		// §8, §6: the line of a carried verdict names the head on the new trunk commit first, as the gate and the merge tool
+		// read a line, then where it was carried from and what the carry ran and kept; while it is carried it is pending and says so.
+		"the line of a carry says where it was carried from": func(t *testing.T) {
+			cs, p := lineCase(t, pullOf(repoA, 7, head1))
+			v := passVerdict()
+			v.Trunk = map[string]string{repoA: trunkA}
+			v.Beside = map[string]string{catalogueRepository: trunkS2}
+			v.CarriedFrom = map[string]string{repoA: trunkA2, catalogueRepository: trunkS}
+			line := Line(v, cs, p, nil, nil, nil)
+			if !strings.HasPrefix(line, "pass 111111111111 on aaaaaaaaaaaa | carried from abababababab, mesh-catalog 555555555555 | unit 12 run") {
+				t.Errorf("the carried line = %q", line)
+			}
+			if head, trunk := checkWordsOf(line); head != head1[:12] || trunk != trunkA[:12] {
+				t.Errorf("the line names %s on %s first, want the head on the new trunk", head, trunk)
+			}
+			cs.CarriedFrom = map[string]string{repoA: trunkA2}
+			pending := Line(delivery.Verdict{State: delivery.VerdictRunning}, cs, p, nil, nil, nil)
+			if !strings.HasPrefix(pending, "being carried to 111111111111 on aaaaaaaaaaaa | from abababababab") {
+				t.Errorf("the pending line of a carry = %q", pending)
+			}
+		},
+		// §3 (review round 1): two approved merges in one turn whose trunk moved each get their carry; neither holds the other's.
+		"two merges waiting in one turn each get their carry": func(t *testing.T) {
+			var r *rig
+			j := &judgeFunc{f: func(context.Context, *Case, int) (Outcome, error) { return Outcome{Verdict: passing()}, nil }}
+			r = newRig(t, j)
+			candA, candC := candidateOf(t, "feat/a", pullOf(repoA, 7, head1)), candidateOf(t, "feat/c", pullOf(repoA, 8, head2))
+			r.ch.Candidate(ctx, "feat%2Fa", candA)
+			r.ch.Candidate(ctx, "feat%2Fc", candC)
+			r.ch.Wait()
+			a, _ := delivery.DecodeCandidate(candA)
+			c, _ := delivery.DecodeCandidate(candC)
+			at := time.Date(2026, 10, 26, 9, 0, 0, 0, time.UTC)
+			turn, err := delivery.EncodeTurn(delivery.Turn{Repository: repoA, Waiting: []delivery.TurnWait{
+				{Group: "feat/a", Heads: GateHeads(a), Approved: at, Since: at}, {Group: "feat/c", Heads: GateHeads(c), Approved: at.Add(time.Minute), Since: at}}})
+			if err != nil {
+				t.Fatal(err)
+			}
+			turns := &Turns{}
+			turns.Put(turnKey(t, repoA), turn, false)
+			r.ch.Turns = turns
+			r.setTrunks(t, map[string]string{repoA: trunkA2, repoSDK: trunkS}) // a third merge moves the trunk under both
+			r.ch.TrunkMoved(ctx)
+			r.ch.Wait()
+			for _, cand := range [][]byte{candA, candC} {
+				group := map[bool]string{true: "feat/a", false: "feat/c"}[string(cand) == string(candA)]
+				if v := r.verdict(t, keyOf(t, group, cand)); v.Trunk[repoA] != trunkA2 || v.CarriedFrom[repoA] != trunkA {
+					t.Errorf("%s: verdict on %v carried from %v; want its carry claimed and done", group, v.Trunk, v.CarriedFrom)
+				}
+			}
+		},
+		// §6 (review round 1): the node-engine read at the commit the mesh runs is named, and a new running commit is carried.
+		"a new running node-engine is carried": func(t *testing.T) {
+			runs := runsAt{nodeEngineModule: trunkS}
+			j := &judgeFunc{f: func(_ context.Context, c *Case, _ int) (Outcome, error) {
+				return Outcome{Verdict: passing(), Beside: map[string]string{nodeEngineRepo: runs[nodeEngineModule]}}, nil
+			}}
+			r := newRig(t, j)
+			r.ch.Runs = runs
+			cand := candidateOf(t, "feat/x", pullOf(repoA, 7, head1))
+			r.ch.Candidate(ctx, "feat%2Fx", cand)
+			r.ch.Wait()
+			r.ch.TrunkMoved(ctx) // nothing moved: nothing is carried
+			r.ch.Wait()
+			runs[nodeEngineModule] = trunkS2
+			r.ch.TrunkMoved(ctx) // what the indexer's watch does when mesh-host's running commit changes
+			r.ch.Wait()
+			v := r.verdict(t, keyOf(t, "feat/x", cand))
+			if j.count() != 2 || v.CarriedFrom[nodeEngineRepo] != trunkS || v.Beside[nodeEngineRepo] != trunkS2 {
+				t.Errorf("judged %d times, verdict beside %v carried from %v; want one carry over the node-engine's new running commit", j.count(), v.Beside, v.CarriedFrom)
+			}
+		},
+		// §5: a carry that fails names the move it failed on.
+		"a carry that fails names the move": func(t *testing.T) {
+			j := &judgeFunc{f: func(_ context.Context, c *Case, call int) (Outcome, error) {
+				if call == 1 {
+					return Outcome{Verdict: passing()}, nil
+				}
+				return Outcome{Verdict: delivery.Verdict{State: delivery.VerdictFail, Failed: delivery.FailedFirst{Test: "unit: m/a.TestX", Words: "want 4"}}}, nil
+			}}
+			r := newRig(t, j)
+			cand := candidateOf(t, "feat/x", pullOf(repoA, 7, head1))
+			r.ch.Candidate(ctx, "feat%2Fx", cand)
+			r.ch.Wait()
+			r.setTrunks(t, map[string]string{repoA: trunkA2, repoSDK: trunkS})
+			r.ch.TrunkMoved(ctx)
+			r.ch.Wait()
+			v := r.verdict(t, keyOf(t, "feat/x", cand))
+			if v.State != delivery.VerdictFail || v.CarriedFrom != nil || !strings.HasPrefix(v.Failed.Words, "want 4") ||
+				!strings.Contains(v.Failed.Words, repoA+" "+trunkA[:12]+" to "+trunkA2[:12]) {
+				t.Errorf("the failed carry is %s carried from %v with words %q; want the test's words, then the move", v.State, v.CarriedFrom, v.Failed.Words)
+			}
+		},
+	} {
+		t.Run(name, run)
+	}
+}
+
+// checkWordsOf is the head and trunk a line names first, as the gate reads it (mesh-delivery-gate onestatus.go checkLine).
+func checkWordsOf(line string) (string, string) {
+	for _, part := range strings.Split(line, " | ") {
+		f := strings.Fields(part)
+		for i := 0; i+2 < len(f); i++ {
+			if f[i+1] == "on" && len(f[i]) == 12 && len(f[i+2]) == 12 {
+				return f[i], f[i+2]
+			}
+		}
+	}
+	return "", ""
+}

modules/mesh-delivery-checker/internal/check/askagain.go

@@ -0,0 +1,198 @@
+package check
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"strings"
+
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+)
+
+// **A check is asked again by hand** (the lost check of 2026-10-28; tools-are-how-a-module-is-spoken-to: every recovery
+// has a tool). checker_ask_again ends a candidate's running verdict, whose wait judged nothing, with AskedAgainWords and
+// the why; the checker hears it on its watch of its verdicts (Checker.VerdictWritten), ends the check of those heads
+// running in it, and claims and asks it anew, a whole check (IsEnded). It is refused while a step of the candidate's pull
+// requests can still run (checker_status's running_steps): that step's end judges it; and while an ask the check put is
+// still in its build seat's stream, taken by no node (it has no step key yet): asking again then would run the check twice
+// (issue 1791's kind). The checker keeps the asks each running check put in its state asks (AsksState, by verdict key).
+// An ask is not put again under its own id instead: the stream de-duplicates an id within its window, so the copy waiting
+// stays and the new one is dropped, and past the window both would run; nothing takes a put ask back (buildrun.Asker).
+
+// AsksState is the checker's state of the asks each running check put, by verdict key (CheckAsks); AsksBucket its bucket.
+const (
+	AsksState  = "asks"
+	AsksBucket = delivery.CheckerModule + "_" + AsksState
+)
+
+// CheckAsks are the asks a check put, in order, as the state asks keeps them while it runs; its end deletes the key.
+type CheckAsks struct {
+	Asks []string `json:"asks"`
+}
+
+// AsksKV is the state asks: a KV whose key a check's end deletes, so the state holds only the checks that run.
+type AsksKV interface {
+	KV
+	Delete(ctx context.Context, key string) error
+}
+
+// forgetAsks deletes the asks a check put at its end; one that cannot be deleted is said, and the next check of the same
+// heads writes the key anew.
+func (ch *Checker) forgetAsks(ctx context.Context, key string) {
+	if err := ch.Asks.Delete(ctx, key); err != nil {
+		ch.logf("%s: the asks it put could not be forgotten at its end: %v", key, err)
+	}
+}
+
+// recordAsks keeps the asks a check put under its verdict key; nil Asks keeps nothing. A record that cannot be written
+// is said: checker_ask_again then refuses the check, as it cannot tell whether its ask waits in a stream.
+func (ch *Checker) recordAsks(ctx context.Context, key string, asks []string) {
+	if ch.Asks == nil {
+		return
+	}
+	data, err := json.Marshal(CheckAsks{Asks: asks})
+	if err == nil {
+		_, err = putOnce(ctx, ch.Asks, key, data, func(cur []byte) bool { return string(cur) == string(data) })
+	}
+	if err != nil {
+		ch.logf("%s: the asks it put cannot be kept (%v), so %s refuses it", key, err, AskAgainTool)
+	}
+}
+
+// AskAgainTool asks a candidate's check again by hand.
+const AskAgainTool = "checker_ask_again"
+
+// AskedAgainWords open the words of a verdict AskAgainTool wrote; the why follows.
+const AskedAgainWords = EndedWords + "asked again by hand (" + AskAgainTool + "): "
+
+// errAskedAgain is the cause a running check is ended with when its verdict was asked again by hand.
+var errAskedAgain = errors.New("its verdict was asked again by hand (" + AskAgainTool + ")")
+
+// IsAskedAgain says whether a verdict was written by AskAgainTool.
+func IsAskedAgain(v delivery.Verdict) bool {
+	return IsEnded(v) && strings.HasPrefix(v.Failed.Words, AskedAgainWords)
+}
+
+// VerdictEntry is the verdicts state as the ask-again tool writes it: a key's value and revision (nil and 0 for none),
+// and a compare-and-set.
+type VerdictEntry interface {
+	Entry(key string) (json.RawMessage, uint64, error)
+	Update(key string, value []byte, revision uint64) error
+}
+
+// AskedAgain is the answer of AskAgainTool.
+type AskedAgain struct {
+	Key  string `json:"key"`
+	Was  string `json:"was"`
+	Said string `json:"said"`
+	Note string `json:"note"`
+}
+
+// AskAgain ends the running verdict of the group's candidate as asked again by hand, saying why. It refuses a group with
+// no candidate, a verdict that is not running (a pass or a failure stands until a push or a trunk move), one a step of
+// whose pull requests can still run, and one whose asks are not known or one of which no node took yet.
+func (r Reader) AskAgain(w VerdictEntry, group, why string) (AskedAgain, error) {
+	why = strings.TrimSpace(why)
+	if group == "" || why == "" {
+		return AskedAgain{}, fmt.Errorf("give the group and why it is asked again")
+	}
+	if w == nil {
+		return AskedAgain{}, fmt.Errorf("the verdicts state cannot be written here")
+	}
+	c, ok := r.candidate(group)
+	if !ok {
+		return AskedAgain{}, fmt.Errorf("no candidate is held for the group %q", group)
+	}
+	key, err := delivery.CheckerVerdictKey(c.Group, c.HeadsHash)
+	if err != nil {
+		return AskedAgain{}, err
+	}
+	raw, rev, err := w.Entry(key)
+	if err != nil {
+		return AskedAgain{}, fmt.Errorf("%s cannot be read: %w", key, err)
+	}
+	if len(raw) == 0 {
+		return AskedAgain{}, fmt.Errorf("%s holds no verdict: the checker claims its check when it looks at the candidate (%s)", key, StatusReadTool)
+	}
+	v, err := delivery.DecodeVerdict(raw)
+	if err != nil {
+		return AskedAgain{}, fmt.Errorf("%s holds what is not a verdict: %w", key, err)
+	}
+	if v.State != delivery.VerdictRunning {
+		return AskedAgain{}, fmt.Errorf("%s is %s, not running: a verdict stands until a push or a trunk move asks it again", key, v.State)
+	}
+	steps := r.readSteps()
+	for _, rs := range steps.running {
+		if asksOf(c, rs.What) {
+			return AskedAgain{}, fmt.Errorf("a step of it runs: %s %s on %s since %s (%s); its end judges it", rs.Module, rs.ID, rs.Node, rs.Since, rs.What)
+		}
+	}
+	if r.AskState.Get == nil {
+		return AskedAgain{}, fmt.Errorf("the checker's asks are not readable here, so whether its ask waits in a build seat's stream cannot be told")
+	}
+	kept, err := r.AskState.Get(key)
+	var put CheckAsks
+	if err == nil && len(kept) > 0 {
+		err = json.Unmarshal(kept, &put)
+	}
+	if err != nil || len(put.Asks) == 0 {
+		return AskedAgain{}, fmt.Errorf("the checker names no ask of %s (%v), so whether one waits in a build seat's stream cannot be told; asking again could run it twice", key, err)
+	}
+	taken := map[string]bool{}
+	for _, s := range steps.all {
+		taken[s.step.ID] = true
+	}
+	for _, id := range put.Asks {
+		if !taken[id] {
+			return AskedAgain{}, fmt.Errorf("its ask %s waits in its build seat's stream, taken by no node yet: asking again would run it twice; "+
+				"the seats' backlog is in mesh-delivery-view.build_usage", id)
+		}
+	}
+	words := AskedAgainWords + why
+	ended := delivery.Verdict{Group: v.Group, Heads: v.Heads, Trunk: v.Trunk, State: delivery.VerdictFail,
+		Failed: delivery.FailedFirst{Machine: "checker", Words: words}}
+	data, err := delivery.EncodeVerdict(ended)
+	if err != nil {
+		return AskedAgain{}, err
+	}
+	if err := w.Update(key, data, rev); err != nil {
+		return AskedAgain{}, fmt.Errorf("%s changed while it was asked again, so it was not; read it again: %w", key, err)
+	}
+	return AskedAgain{Key: key, Was: v.State, Said: words,
+		Note: "the checker hears it on its watch of its verdicts, ends the wait that judged nothing and asks the check anew, whole; " +
+			VerdictsReadTool + " shows it running again"}, nil
+}
+
+// VerdictWritten takes a change of the checker's verdicts in (its watch, updates only): a verdict AskAgainTool wrote ends
+// the check of those heads running in this process, which then considers them again; with none running, the candidate
+// that holds them is considered at once. Any other verdict is the checker's own, and left.
+func (ch *Checker) VerdictWritten(ctx context.Context, key string, value []byte) {
+	v, err := delivery.DecodeVerdict(value)
+	if err != nil || !IsAskedAgain(v) {
+		return
+	}
+	ch.init()
+	ch.mu.Lock()
+	if l, ok := ch.live[key]; ok {
+		l.end(errAskedAgain)
+		ch.mu.Unlock()
+		ch.logf("%s: %s; the check running for it is ended and asked again", key, v.Failed.Words)
+		return
+	}
+	var group string
+	var cand delivery.Candidate
+	for k, c := range ch.known {
+		if vk, err := delivery.CheckerVerdictKey(c.Group, c.HeadsHash); err == nil && vk == key {
+			group, cand = k, c
+			break
+		}
+	}
+	ch.mu.Unlock()
+	if group == "" {
+		ch.logf("%s: %s, but no candidate holds these heads, so nothing is asked", key, v.Failed.Words)
+		return
+	}
+	ch.logf("%s: %s; asked again", key, v.Failed.Words)
+	ch.consider(ctx, group, cand)
+}

modules/mesh-delivery-checker/internal/check/awaiting.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"strings"
 
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 )
@@ -96,9 +97,19 @@ func notJudged(v delivery.Verdict) bool {
 	return v.Composition != nil && v.Composition.State == delivery.CompositionNotRun && v.Composition.Words == delivery.AssignerNotRunning
 }
 
+// unanswered says whether a verdict failed only on its composition, and that only because nodes the change places did
+// not answer its placement in time (delivery.CompositionUnanswered, ADR 0559 §5): its tests passed (a composition is read
+// only into a passing verdict), so a later composition of the same heads is taken in on its event, with no new check
+// (ADR 0548 §1: a part of the mesh not heard is judged again when it is heard).
+func unanswered(v delivery.Verdict) bool {
+	return v.State == delivery.VerdictFail && v.Composition != nil && v.Composition.State == delivery.CompositionFail &&
+		strings.Contains(v.Composition.Words, delivery.CompositionUnanswered) && v.Failed.Words == v.Composition.Words
+}
+
 // Composed takes in a composition the assigner wrote after the check's verdict said it was not judged because the
-// assigner was not running (the assigner started since): the verdict and its status are written again with it. A
-// composition of heads no candidate holds now, or of a verdict that judged its composition, is left.
+// assigner was not running (the assigner started since), or after it failed only because placed nodes had not answered
+// (unanswered): the verdict and its status are written again with it. A composition of heads no candidate holds now, or
+// of a verdict that judged its composition otherwise, is left.
 func (ch *Checker) Composed(ctx context.Context, comp delivery.CompositionVerdict) {
 	ch.init()
 	if comp.State == delivery.CompositionWaits {
@@ -123,10 +134,21 @@ func (ch *Checker) Composed(ctx context.Context, comp delivery.CompositionVerdic
 		return
 	}
 	v, err := delivery.DecodeVerdict(cur)
-	if err != nil || v.State != delivery.VerdictPass || !notJudged(v) {
+	if err != nil {
+		return
+	}
+	switch {
+	case v.State == delivery.VerdictPass && notJudged(v):
+	case unanswered(v) && comp.Words != v.Composition.Words:
+		// The nodes answered since (or another failure stands now): the verdict is its tests' pass with this composition.
+		v.State, v.Failed = delivery.VerdictPass, delivery.FailedFirst{}
+	default:
 		return
 	}
 	withComposition(&v, comp)
+	if v.Composition != nil && v.Composition.State != delivery.CompositionNotRun {
+		v.Composition.FPSet = cs.FPSet
+	}
 	data, err := delivery.EncodeVerdict(v)
 	if err != nil {
 		ch.logf("%s: the verdict with its composition cannot be written: %v", cs.Key, err)

modules/mesh-delivery-checker/internal/check/awaiting_test.go

@@ -113,6 +113,27 @@ func TestTheAssignerStartingBringsTheComposition(t *testing.T) {
 			t.Errorf("the status's line says %q", o.Text)
 		}
 	}
+
+	// ADR 0559 §5: a verdict that failed only because a placed node had not answered takes the same heads' later
+	// composition in on its event, a pass making it pass with no new check; a composition failing the same way is left.
+	ch, cs := checkerWithNotJudged(t)
+	silent := delivery.CompositionVerdict{Group: cs.Group, Heads: cs.HeadsHash, State: delivery.CompositionFail, SDK: "x", Machine: "g14",
+		Words: "g14 (offline) " + delivery.CompositionUnanswered}
+	ch.Composed(context.Background(), silent)
+	for _, row := range []struct {
+		name  string
+		comp  delivery.CompositionVerdict
+		state string
+	}{
+		{"the same failure again", silent, delivery.VerdictFail},
+		{"the node's answer", delivery.CompositionVerdict{Group: cs.Group, Heads: cs.HeadsHash, State: delivery.CompositionPass, SDK: "x"}, delivery.VerdictPass},
+	} {
+		ch.Composed(context.Background(), row.comp)
+		raw, _, _, _ := ch.Verdicts.Get(context.Background(), cs.Key)
+		if v, err := delivery.DecodeVerdict(raw); err != nil || v.State != row.state || v.Composition == nil || v.Composition.State != row.comp.State {
+			t.Errorf("%s: the verdict is %+v, %v", row.name, v, err)
+		}
+	}
 }
 
 // checkerWithNotJudged is a checker holding a candidate whose passing verdict said its composition was not judged.

modules/mesh-delivery-checker/internal/check/beside.go

@@ -12,8 +12,18 @@ type BesideRef struct {
 	Repository string `json:"repository"`
 	Commit     string `json:"commit"`
 	Ref        string `json:"ref,omitempty"`
+	// atTrunk says the sibling was read at its trunk's head, so a move of that trunk puts the verdict out of date and is
+	// carried (novox/hq ADR 0548 §6). Never sent: the node-engine at the commit the mesh runs, mesh-sdk at a pin and a
+	// group's member at its head do not move with a trunk.
+	atTrunk bool
+	// runs says the sibling was read at the commit the mesh runs (the node-engine, the indexer's record of mesh-host): a new
+	// running commit puts the verdict out of date and is carried (ADR 0548 §6). Never sent.
+	runs bool
 }
 
+// NodeEngineModule is the module whose running commit the node-engine sibling is read at.
+const NodeEngineModule = nodeEngineModule
+
 const (
 	catalogueRepository = "novox/mesh-catalog"
 	nodeEngineRepo      = "novox/mesh-host"
@@ -51,18 +61,21 @@ func (j *Examiner) besideFor(ctx context.Context, c *Case, p Pull) ([]BesideRef,
 		switch {
 		case repo == catalogueRepository:
 			if head := heads[repo]; head != "" {
-				out = append(out, BesideRef{Repository: repo, Commit: head})
+				out = append(out, BesideRef{Repository: repo, Commit: head, atTrunk: c.member(repo) == nil})
 			}
 		case repo == nodeEngineRepo:
 			commit := ""
 			if j.Runs != nil {
 				commit = j.Runs.CommitOf(nodeEngineModule)
 			}
+			atTrunk := false
 			if commit == "" {
-				commit = heads[repo]
+				commit, atTrunk = heads[repo], true
 			}
 			if commit != "" {
-				out = append(out, BesideRef{Repository: repo, Commit: commit})
+				// Named in the verdict either way (ADR 0548 §6, issue 568's own example): at the commit the mesh runs, a new
+				// running commit puts the verdict out of date; at the trunk, a trunk move does (Checker.besideNow).
+				out = append(out, BesideRef{Repository: repo, Commit: commit, atTrunk: atTrunk, runs: !atTrunk})
 			}
 		case repo == SDKRepository && p.Repository == controllerRepo && j.Forge != nil:
 			text, err := j.Forge.File(ctx, p.Repository, "go.mod", p.Head)
@@ -82,7 +95,7 @@ func (j *Examiner) besideFor(ctx context.Context, c *Case, p Pull) ([]BesideRef,
 			if member := c.member(repo); member != nil {
 				out = append(out, BesideRef{Repository: repo, Commit: member.Head, Ref: refOf(member.Number)})
 			} else if head := heads[repo]; head != "" {
-				out = append(out, BesideRef{Repository: repo, Commit: head})
+				out = append(out, BesideRef{Repository: repo, Commit: head, atTrunk: true})
 			} else if repo == controllerRepo && p.Repository == nodeEngineRepo {
 				// The node-engine's step-nine test judges the controller's own manifest and fails without it (issue 1295): a
 				// checker that cannot place it says so, where placing none left that test to skip.
@@ -108,3 +121,13 @@ func refOf(number int) string {
 	}
 	return "refs/pull/" + strconv.Itoa(number) + "/head"
 }
+
+// besideAtTrunk are the siblings of refs read at their trunk's head that the case does not merge, by repository: what a
+// verdict names as Beside (ADR 0548 §6).
+func besideAtTrunk(c *Case, refs []BesideRef, into map[string]string) {
+	for _, r := range refs {
+		if _, merged := c.Trunk[r.Repository]; (r.atTrunk || r.runs) && !merged {
+			into[r.Repository] = r.Commit
+		}
+	}
+}

modules/mesh-delivery-checker/internal/check/binaries.go

@@ -0,0 +1,42 @@
+package check
+
+import (
+	"fmt"
+	"strings"
+)
+
+// A change that adds or modifies a compiled program fails (issue 1577): it is build output, `go build` in a module's folder
+// writes one beside go.mod, and `git add -A` takes it. The build module's fetch step, which holds the merged clone, reads the
+// first bytes of each changed file and reports the programs (mesh-sdk buildstep.MergeInto); the checker judges the answer.
+
+// NoProgramsReported is the warning of a build module whose fetch answered no programs field: an older module, which cannot
+// tell, so the check does not refuse a program it did not look for.
+const NoProgramsReported = "the build module did not report programs: a compiled program in the change is not refused"
+
+// checkBinariesOf fails a pull request whose change adds or modifies a compiled program, naming each file. It judges the
+// first fetch answer of the pull request, whichever build module gave it; a build module that reports no programs leaves a
+// warning on the check and passes it.
+func (st *state) checkBinariesOf(t *target) verdictPtr {
+	key := fmt.Sprintf("%s#%d", t.pull.Repository, t.pull.Number)
+	if t.fetched.Merge == "" {
+		return nil // no merge was made: nothing was changed to judge
+	}
+	if t.fetched.Programs == nil {
+		st.c.note(fmt.Sprintf("%s: %s (%s)", key, NoProgramsReported, t.module))
+		st.c.warn(key, fmt.Sprintf("a compiled program is not refused: %s reported no programs", t.module))
+		st.j.logf("%s: %s (%s)", key, NoProgramsReported, t.module)
+		return nil
+	}
+	var found []string
+	for _, p := range *t.fetched.Programs {
+		if p.Commit != "" {
+			found = append(found, fmt.Sprintf("%s: a compiled program added in %s and removed later: it stays in history; squash the branch (issue 1577)", p.Path, short12(p.Commit)))
+			continue
+		}
+		found = append(found, p.Path+": a compiled program is build output: remove it and add it to .gitignore (issue 1577)")
+	}
+	if len(found) > 0 {
+		return failed(t.node, fmt.Sprintf("%s: %s", key, strings.Join(found, "; ")))
+	}
+	return nil
+}

modules/mesh-delivery-checker/internal/check/binaries_test.go

@@ -0,0 +1,63 @@
+package check
+
+import (
+	"slices"
+	"strings"
+	"testing"
+
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+)
+
+func TestAChangeWhoseFetchReportsProgramsFailsNamingEachFile(t *testing.T) { // 1577
+	prog := func(p ...string) *[]ProgramFile {
+		out := []ProgramFile{}
+		for _, f := range p {
+			path, commit, _ := strings.Cut(f, "@") // `path@commit`: added by a commit of the branch and removed later
+			out = append(out, ProgramFile{Path: path, Kind: "ELF", Commit: commit})
+		}
+		return &out
+	}
+	for _, c := range []struct {
+		name     string
+		programs *[]ProgramFile
+		fail     []string // paths named; none passes
+		warned   bool     // the build module reported no programs field
+	}{
+		{"none found", prog(), nil, false},
+		{"one program", prog("modules/m/m"), []string{"modules/m/m"}, false},
+		{"two programs", prog("a/x", "b/y"), []string{"a/x", "b/y"}, false},
+		{"added and removed in the branch", prog("gone/prog@0123456789abcdef0123"), []string{"gone/prog: a compiled program added in 0123456789ab and removed later: it stays in history; squash the branch (issue 1577)"}, false},
+		{"an older build module reports nothing", nil, nil, true},
+	} {
+		b := newBench(t)
+		b.fetch.Merge, b.fetch.Programs = "mmmm", c.programs
+		cs := caseOf(t, pullOf(repoA, 7, head1))
+		v := b.judge(t, cs).Verdict
+		if got := slices.ContainsFunc(cs.Notes(), func(n string) bool { return strings.Contains(n, NoProgramsReported) }); got != c.warned {
+			t.Errorf("%s: warned = %v, want %v (%v)", c.name, got, c.warned, cs.Notes())
+		}
+		line := Line(v, cs, cs.Pulls[0], nil, nil, nil)
+		if got := strings.Contains(line, "a compiled program is not refused: mesh-build-go reported no programs"); got != c.warned {
+			t.Errorf("%s: the status line holds the warning = %v, want %v: %s", c.name, got, c.warned, line)
+		}
+		if len(c.fail) == 0 {
+			if v.State != delivery.VerdictPass {
+				t.Errorf("%s: verdict = %+v", c.name, v)
+			}
+			continue
+		}
+		if v.State != delivery.VerdictFail {
+			t.Errorf("%s: verdict = %+v, want a failure", c.name, v)
+			continue
+		}
+		for _, p := range c.fail {
+			want := p
+			if !strings.Contains(p, " added in ") {
+				want = p + ": a compiled program is build output: remove it and add it to .gitignore (issue 1577)"
+			}
+			if !strings.Contains(v.Failed.Words, want) {
+				t.Errorf("%s: words %q do not name %s", c.name, v.Failed.Words, p)
+			}
+		}
+	}
+}

modules/mesh-delivery-checker/internal/check/case.go

@@ -43,12 +43,43 @@ type Case struct {
 	Try *TryOptions
 
 	notesMu sync.Mutex
-	notes   []string
+	// warnings are, by pull request, what part of its check did not run (Case.warn).
+	warnings map[string]string
+	notes    []string
+	// asks are the ids of the asks the check put on the build seats' streams, in order: a try names them (Try.Asks).
+	asks []string
+	// Watch, when set, hears each ask the check puts, as it is put (step nil), and each value its step key takes while
+	// the check waits for it: the node that took it, the phase it says, its end. A try writes them into its record, so a
+	// running try names its asks and where each stands (issue 1890). Called from the check's goroutines; it must not block
+	// for long.
+	Watch func(askID string, step *delivery.Step)
 	// Progress says what the check is doing, so a check that ran past its bound names the step it was stuck at.
 	Progress *Progress
-	// Kind is what asked the check (KindNew, KindNodes, KindTrunk): a re-judge after a trunk move is asked on the build
-	// seats' recheck stream, every other check on check (ADR 0536 §4).
+	// Kind is what asked the check (KindNew, KindNodes, KindTrunk): a carry after a trunk or sibling move is asked on the
+	// build seats' recheck stream, every other check on check (ADR 0536 §4, ADR 0548 §5).
 	Kind string
+	// CarriedFrom are, for the carry of a verdict that passed, the trunk and sibling commits it was judged on (ADR 0548 §5);
+	// nil for a whole check.
+	CarriedFrom map[string]string
+	// FPSet is the candidate's fingerprint set (Candidate.FPSet): a composition names the set it judged.
+	FPSet string
+	// Composition is, for a carry, the composition that passed on the same fingerprint set: it is kept and not asked again,
+	// since no fingerprint of a module it composed changed (ADR 0548 §5). Nil composes.
+	Composition *delivery.Composition
+}
+
+// Asked records the id of an ask the check put.
+func (c *Case) Asked(id string) {
+	c.notesMu.Lock()
+	c.asks = append(c.asks, id)
+	c.notesMu.Unlock()
+}
+
+// Asks are the ids of the asks the check put, in order.
+func (c *Case) Asks() []string {
+	c.notesMu.Lock()
+	defer c.notesMu.Unlock()
+	return append([]string(nil), c.asks...)
 }
 
 // Progress is the step a check is at, written by the check and read when its bound passes.
@@ -80,11 +111,11 @@ func CaseOf(c delivery.Candidate, trunk map[string]string) *Case {
 	if err != nil {
 		return nil
 	}
-	cs := &Case{Key: key, Group: c.Group, HeadsHash: c.HeadsHash, Heads: GateHeads(c), Trunk: map[string]string{}, Progress: &Progress{}}
+	cs := &Case{Key: key, Group: c.Group, HeadsHash: c.HeadsHash, Heads: GateHeads(c), Trunk: map[string]string{}, Progress: &Progress{}, FPSet: c.FPSet}
 	for _, p := range c.Pulls {
 		switch head, known := trunk[p.Repository]; {
 		case !known || head == "":
-			cs.Left = append(cs.Left, fmt.Sprintf("%s#%d: the trunk head of %s is not known", p.Repository, p.Number, p.Repository))
+			cs.Left = append(cs.Left, fmt.Sprintf("%s#%d: %s", p.Repository, p.Number, UntrunkedWordsOf([]string{p.Repository})))
 		default:
 			cs.Pulls = append(cs.Pulls, Pull{Repository: p.Repository, Number: p.Number, Head: p.Head.Head, Trunk: head, Modules: p.Modules, Fps: p.Fps})
 			cs.Trunk[p.Repository] = head
@@ -102,6 +133,42 @@ func CaseOf(c delivery.Candidate, trunk map[string]string) *Case {
 	return cs
 }
 
+// UntrunkedWords open the words of a verdict, and of a status, of a pull request that cannot be judged because the gate's
+// source.main names no trunk head of its repository (issue 1422): never a failure of the change, and judged whole once the
+// trunk head is known. It is said loudly, never left silently "new".
+const UntrunkedWords = "cannot be judged: the trunk head of "
+
+// UntrunkedWordsOf are those words for the repositories whose trunk head is not known, in order, each named once.
+func UntrunkedWordsOf(repos []string) string {
+	rs := slices.Clone(repos)
+	slices.Sort(rs)
+	rs = slices.Compact(rs)
+	return UntrunkedWords + strings.Join(rs, ", ") + " is not known: the gate's source.main names none, so there is no commit to merge it onto"
+}
+
+// IsUntrunked says whether a verdict says its heads cannot be judged for want of a trunk head (UntrunkedWords).
+func IsUntrunked(v delivery.Verdict) bool {
+	return v.State == delivery.VerdictFail && v.Failed.Machine == "checker" && strings.HasPrefix(v.Failed.Words, UntrunkedWords)
+}
+
+// leftOf are the pull requests of a candidate whose repository has no trunk head known, with Trunk empty, in repository and
+// number order; nil when every repository's is known.
+func leftOf(c delivery.Candidate, trunk map[string]string) []Pull {
+	var out []Pull
+	for _, p := range c.Pulls {
+		if trunk[p.Repository] == "" {
+			out = append(out, Pull{Repository: p.Repository, Number: p.Number, Head: p.Head.Head, Modules: p.Modules, Fps: p.Fps})
+		}
+	}
+	sort.SliceStable(out, func(i, j int) bool {
+		if out[i].Repository != out[j].Repository {
+			return out[i].Repository < out[j].Repository
+		}
+		return out[i].Number < out[j].Number
+	})
+	return out
+}
+
 // GateHeads is the hash the gate matches the members an Approve covers by (mesh-catalog mesh-delivery-gate onestatus.go
 // headsOf): delivery.HeadsHash over every pull request of the candidate, hq's included, as
 // `<owner/name lowercase>#<number>=<full head sha lowercase>`. A lone pull request is a group of one. Empty for a candidate
@@ -162,6 +229,23 @@ func (c *Case) note(s string) {
 	}
 }
 
+// warn says of a pull request (pullKey) that a part of its check did not run, in words for its status line (issue 1577).
+func (c *Case) warn(key, words string) {
+	c.notesMu.Lock()
+	defer c.notesMu.Unlock()
+	if c.warnings == nil {
+		c.warnings = map[string]string{}
+	}
+	c.warnings[key] = words
+}
+
+// Warning is what warn said of a pull request, or "".
+func (c *Case) Warning(key string) string {
+	c.notesMu.Lock()
+	defer c.notesMu.Unlock()
+	return c.warnings[key]
+}
+
 // Notes are the words noted on the case, in the order they were noted.
 func (c *Case) Notes() []string {
 	c.notesMu.Lock()

modules/mesh-delivery-checker/internal/check/checker.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"sort"
 	"strings"
 	"sync"
 	"time"
@@ -42,6 +43,9 @@ type Outcome struct {
 	// Judged says, by pull request (pullKey), which program judged a change to a build module (ADR 0535 §5); a pull request
 	// that changes none is not named.
 	Judged map[string]string
+	// Beside are the siblings the check read at their trunk's head, by repository (ADR 0548 §6): the verdict names them, and
+	// a move of one is carried.
+	Beside map[string]string
 }
 
 // BuildNote is the state of a candidate's module build, by module: built, failed or waiting (ADR 0484 clause 7).
@@ -65,14 +69,28 @@ type Checker struct {
 	Owed     KV
 	Judge    Judge
 	Trunks   interface{ Heads() map[string]string }
+	// Runs says which commit the mesh runs of a module (the indexer's modules): the node-engine a verdict read beside at its
+	// running commit is out of date when that commit moves (ADR 0548 §6); nil reads every sibling at its trunk.
+	Runs interface{ CommitOf(module string) string }
+	// Turns are the gate's merge turns (ADR 0548 §3): no check is claimed of a repository a turn names, but the check of the
+	// waiting delivery's own heads; nil holds none.
+	Turns interface {
+		Holding(repositories []string, heads string) (string, delivery.TurnWait, bool)
+	}
 	// Bound is how long one check may run; none when 0 (DefaultBound).
 	Bound time.Duration
+	// Asks keeps the asks each running check put, by verdict key (AsksState), for checker_ask_again; nil keeps none.
+	Asks AsksKV
 	// Link is the base of the address a status points at; the verdict key follows.
 	Link string
 	// Announce says a status was written (EventOwedWritten); nil says nothing.
 	Announce Announcer
 	Now      func() time.Time
 	Logf     func(format string, args ...any)
+	// Settle is how long a group's heads must stay the same after the candidate last changed them before its check starts
+	// (issue 1890): the members of a group are announced one after another, and a check of each partial set is thrown
+	// away at the next. None when 0; DefaultSettle in the module.
+	Settle time.Duration
 
 	once      sync.Once
 	wg        sync.WaitGroup
@@ -83,15 +101,78 @@ type Checker struct {
 	tried     map[string]bool               // by verdict key: looked at since this process started
 	epoch     uint64                        // changes of the nodes seen since this process started
 	nodesFail map[string]uint64             // by verdict key: the epoch a failure of the nodes was written at
+	held      map[string]string             // by verdict key: the turn that holds its check off, as last said
+	live      map[string]liveCheck          // by verdict key: the check running in this process, ended when its heads go
+	settling  map[string]*window            // by candidates key: the window its heads settle in
+}
+
+// liveCheck is a check running in this process: the candidates key of its group and the end of its run.
+type liveCheck struct {
+	group string
+	end   context.CancelCauseFunc
+}
+
+// window is a group's settle window: aborted with errUnsettled when its heads change again or the group goes, and with
+// errSettled to end it at once.
+type window struct{ abort context.CancelCauseFunc }
+
+var (
+	errUnsettled = errors.New("the group's heads changed again")
+	errSettled   = errors.New("the group's heads settled")
+)
+
+// settleNow ends the settle window of every group at once, as if Settle had passed.
+func (ch *Checker) settleNow() {
+	ch.mu.Lock()
+	defer ch.mu.Unlock()
+	for _, w := range ch.settling {
+		w.abort(errSettled)
+	}
+}
+
+// DefaultSettle is the module's Settle (issue 1890). On 2026-10-26 the three members of a group were announced within 2.8
+// seconds of each other (20:31:52.3, :53.7, :55.1 UTC), a session opening or pushing them one API call after another;
+// fifteen seconds holds five times that, and costs a check of 10 to 18 minutes under 2.5 % of its time. A member that comes
+// later still is no waste beyond its asks already taken: the check of the heads it replaced is ended at once.
+const DefaultSettle = 15 * time.Second
+
+// EndedWords open the words of a verdict the checker ended without judging it, its heads no candidate's any more (issue
+// 1890): never a failure of the change, and judged whole if a candidate holds those heads again.
+const EndedWords = "ended: "
+
+// IsEnded says whether a verdict was ended without being judged (EndedWords).
+func IsEnded(v delivery.Verdict) bool {
+	return v.State == delivery.VerdictFail && v.Failed.Machine == "checker" && strings.HasPrefix(v.Failed.Words, EndedWords)
+}
+
+// superseded is the cause a running check is ended with: the heads that replaced its own, or none when its group went.
+type superseded struct{ by string }
+
+func (s superseded) Error() string {
+	if s.by == "" {
+		return EndedWords + "no candidate holds these heads any more: the group was closed or merged"
+	}
+	return EndedWords + "superseded by " + s.by
 }
 
 func (ch *Checker) init() {
 	ch.once.Do(func() {
 		ch.known, ch.inflight, ch.again, ch.tried = map[string]delivery.Candidate{}, map[string]bool{}, map[string]bool{}, map[string]bool{}
-		ch.nodesFail = map[string]uint64{}
+		ch.nodesFail, ch.held = map[string]uint64{}, map[string]string{}
+		ch.live, ch.settling = map[string]liveCheck{}, map[string]*window{}
 	})
 }
 
+// endOthers ends every check of the group running in this process whose verdict key is not keep: no candidate holds its
+// heads any more (issue 1890). Called with ch.mu held.
+func (ch *Checker) endOthers(group, keep, by string) {
+	for k, l := range ch.live {
+		if l.group == group && k != keep {
+			l.end(superseded{by: by})
+		}
+	}
+}
+
 func (ch *Checker) logf(format string, args ...any) {
 	if ch.Logf != nil {
 		ch.Logf(format, args...)
@@ -124,17 +205,91 @@ func (ch *Checker) Candidate(ctx context.Context, key string, value []byte) {
 		ch.logf("candidates.%s holds what is not a candidate, left: %v", key, err)
 		return
 	}
+	vkey, _ := delivery.CheckerVerdictKey(c.Group, c.HeadsHash)
 	ch.mu.Lock()
+	prev, had := ch.known[key]
 	ch.known[key] = c
+	// A check of heads this candidate no longer holds is ended at once (issue 1890): a member's new head, a member joining
+	// or leaving.
+	ch.endOthers(key, vkey, GateHeads(c))
+	moved := !had || prev.HeadsHash != c.HeadsHash
+	if ch.Settle > 0 && (moved || ch.settling[key] != nil) {
+		// The group's heads changed: its check waits until they have been the same for Settle, so a group whose members
+		// are announced one after another is checked once, whole. A later change starts the window again. The wait is a
+		// context's bound, no timer (ADR 0437 §8).
+		if w := ch.settling[key]; w != nil {
+			w.abort(errUnsettled)
+		}
+		base, abort := context.WithCancelCause(ctx)
+		w := &window{abort: abort}
+		ch.settling[key] = w
+		ch.wg.Add(1)
+		go func() {
+			defer ch.wg.Done()
+			wait, done := context.WithTimeout(base, ch.Settle)
+			defer done()
+			<-wait.Done()
+			settled := errors.Is(wait.Err(), context.DeadlineExceeded) || errors.Is(context.Cause(wait), errSettled)
+			ch.mu.Lock()
+			if !settled || ch.settling[key] != w {
+				ch.mu.Unlock()
+				return // changed again, forgotten, or the checker stops
+			}
+			delete(ch.settling, key)
+			now, ok := ch.known[key]
+			ch.mu.Unlock()
+			abort(nil)
+			if ok {
+				ch.consider(ctx, key, now)
+			}
+		}()
+		ch.mu.Unlock()
+		return
+	}
 	ch.mu.Unlock()
 	ch.consider(ctx, key, c)
 }
 
-// Forget takes a candidate out (its key was deleted).
+// VerdictDeleted takes the delete of a verdict key in (the checker's watch of its verdicts, issue 1733): the gate asks the
+// operator's Approve only on a verdict, so heads a candidate holds are never left without one. A check of them running in
+// this process writes its verdict anew at its end; otherwise the candidate is considered at once and judged again (or said
+// again to be unjudgeable). A key no candidate holds is said and left.
+func (ch *Checker) VerdictDeleted(ctx context.Context, key string) {
+	ch.init()
+	ch.mu.Lock()
+	if ch.inflight[key] {
+		ch.mu.Unlock()
+		ch.logf("%s: deleted while its check runs; its end writes it anew", key)
+		return
+	}
+	var group string
+	var cand delivery.Candidate
+	for k, c := range ch.known {
+		if vk, err := delivery.CheckerVerdictKey(c.Group, c.HeadsHash); err == nil && vk == key {
+			group, cand = k, c
+			break
+		}
+	}
+	ch.mu.Unlock()
+	if group == "" {
+		ch.logf("%s: deleted, and no candidate holds these heads, so nothing is judged", key)
+		return
+	}
+	ch.logf("%s: deleted; its heads are judged again", key)
+	ch.consider(ctx, group, cand)
+}
+
+// Forget takes a candidate out (its key was deleted): a check of its heads still running is ended, as no candidate holds
+// them any more.
 func (ch *Checker) Forget(key string) {
 	ch.init()
 	ch.mu.Lock()
 	delete(ch.known, key)
+	if w := ch.settling[key]; w != nil {
+		w.abort(errUnsettled)
+		delete(ch.settling, key)
+	}
+	ch.endOthers(key, "", "")
 	ch.mu.Unlock()
 }
 
@@ -171,38 +326,67 @@ func (ch *Checker) heads() map[string]string {
 }
 
 func (ch *Checker) consider(ctx context.Context, key string, c delivery.Candidate) {
-	cs := CaseOf(c, ch.heads())
+	heads := ch.heads()
+	if left := leftOf(c, heads); len(left) > 0 {
+		// A pull request the checker cannot claim (its repository's trunk head is not known) leaves its whole group
+		// unjudged, said in a failure verdict (issue 1422, issue 1733): the gate asks the Approve only on a verdict, and a
+		// pass of the other members would let the group merge with that one never checked.
+		ch.untrunked(ctx, c, left)
+		return
+	}
+	cs := CaseOf(c, heads)
 	if cs == nil {
-		return // nothing to judge: no trunk known
+		return // no pull request at all: nothing to judge
 	}
 	cs.Queued = ch.now()
 	ch.mu.Lock()
+	if ch.settling[key] != nil {
+		ch.mu.Unlock()
+		return // its heads are settling: the window's end considers it (Settle)
+	}
 	if ch.inflight[cs.Key] {
 		ch.again[cs.Key] = true // looked at once more when the check ends, so a change of the trunk is never lost
 		ch.mu.Unlock()
 		return
 	}
 	ch.inflight[cs.Key] = true
+	run, end := context.WithCancelCause(ctx)
+	ch.live[cs.Key] = liveCheck{group: key, end: end}
 	ch.mu.Unlock()
 	ch.wg.Add(1)
 	go func() {
 		defer ch.wg.Done()
+		vkey := cs.Key
+		defer func() {
+			ch.mu.Lock()
+			delete(ch.inflight, vkey)
+			delete(ch.again, vkey)
+			delete(ch.live, vkey)
+			ch.mu.Unlock()
+			again := errors.Is(context.Cause(run), errAskedAgain)
+			end(nil)
+			if again && ctx.Err() == nil {
+				ch.consider(ctx, key, ch.candidate(key, c)) // asked again by hand (AskAgainTool): claimed anew
+			}
+		}()
 		for {
 			// Every check is asked at once: the build seats' streams hold the backlog, a new head's check and a check after a
 			// failure of the nodes on check, a re-judge after a trunk move on recheck, pulled after them (ADR 0525 §4, §9;
 			// ADR 0536 §4). The checker holds no place and no capacity of its own.
-			cs.Kind = ch.kindOf(ctx, cs)
-			ch.try(ctx, key, cs)
+			ch.prepare(ctx, cs)
+			ch.try(ctx, run, key, cs)
 			ch.mu.Lock()
-			more := ch.again[cs.Key]
-			delete(ch.again, cs.Key)
-			if !more || ctx.Err() != nil {
-				delete(ch.inflight, cs.Key)
-				ch.mu.Unlock()
+			more := ch.again[vkey]
+			delete(ch.again, vkey)
+			ch.mu.Unlock()
+			if !more || run.Err() != nil {
 				return
 			}
-			ch.mu.Unlock()
+			// Looked at again for the same heads only: a candidate that moved to other heads has its own check (issue 1890).
 			if next := CaseOf(ch.candidate(key, c), ch.heads()); next != nil {
+				if next.Key != vkey {
+					return
+				}
 				cs = next
 			}
 			cs.Queued = ch.now()
@@ -210,30 +394,203 @@ func (ch *Checker) consider(ctx context.Context, key string, c delivery.Candidat
 	}()
 }
 
+// untrunked says, loudly, that pull requests of a candidate cannot be judged because the gate's source.main names no trunk
+// head of their repository (issue 1422): its verdict key holds a failure that says so, whatever it held before (a running
+// verdict left by a check that can no longer run, or a verdict judged on a trunk that is no longer named: issue 1733), which
+// checker_verdicts and checker_status show; and every pull request of the candidate gets the status error with
+// UntrunkedWords, the members whose trunk is known too, as their group is not judged. It is logged once per head: when a
+// status or the verdict is written, never at a look that finds them already said. Once the trunk head is known the verdict
+// is stale (it names no trunk) and the heads are judged whole (prepare, claim).
+func (ch *Checker) untrunked(ctx context.Context, c delivery.Candidate, left []Pull) {
+	key, err := delivery.CheckerVerdictKey(c.Group, c.HeadsHash)
+	if err != nil {
+		ch.logf("candidates of %s: no verdict key for heads %q, so it cannot be said that they cannot be judged: %v", c.Group, c.HeadsHash, err)
+		return
+	}
+	repos := make([]string, 0, len(left))
+	for _, p := range left {
+		repos = append(repos, p.Repository)
+	}
+	words := UntrunkedWordsOf(repos)
+	v := delivery.Verdict{Group: c.Group, Heads: GateHeads(c), Trunk: map[string]string{}, State: delivery.VerdictFail,
+		Failed: delivery.FailedFirst{Machine: "checker", Words: words}}
+	data, err := delivery.EncodeVerdict(v)
+	if err != nil {
+		ch.logf("%s: %s, and the verdict cannot say so: %v", key, words, err)
+		return
+	}
+	said, err := putOnce(ctx, ch.Verdicts, key, data, func(cur []byte) bool {
+		held, err := delivery.DecodeVerdict(cur)
+		return err == nil && IsUntrunked(held) && held.Failed.Words == words // the same words stand; anything else is replaced
+	})
+	if err != nil {
+		ch.logf("%s: %s, and the verdict cannot say so: %v", key, words, err)
+	}
+	for _, cp := range c.Pulls {
+		okey, err := delivery.CheckerOwedKey(cp.Repository, cp.Number, cp.Head.Head)
+		if err != nil {
+			ch.logf("%s: %v", key, err)
+			continue
+		}
+		o := delivery.Owed{Act: delivery.OwedStatus, Context: delivery.StatusContextCheck, State: "error",
+			Target: strings.TrimSuffix(ch.Link, "/") + "/" + key, Text: clipLine(words, MaxLine)}
+		data, err := delivery.EncodeCheckerOwed(o)
+		if err != nil {
+			ch.logf("%s: the status of %s cannot be written: %v", key, okey, err)
+			continue
+		}
+		wrote, err := putOnce(ctx, ch.Owed, okey, data, func(cur []byte) bool {
+			held, err := delivery.DecodeCheckerOwed(cur)
+			o.V = delivery.Version
+			return err == nil && delivery.SameOwed(held, o)
+		})
+		if err != nil {
+			ch.logf("%s: the status of %s cannot be written: %v", key, okey, err)
+			continue
+		}
+		if wrote {
+			said = true
+			if ch.Announce != nil {
+				ch.Announce(ctx, EventOwedWritten, okey)
+			}
+		}
+	}
+	if said {
+		names := make([]string, 0, len(left))
+		for _, p := range left {
+			names = append(names, fmt.Sprintf("%s#%d@%s", p.Repository, p.Number, short12(p.Head)))
+		}
+		ch.logf("%s: %s %s; the verdict and every status of its group say so (error), and it is judged once the trunk head is known", key, strings.Join(names, ", "), words)
+	}
+}
+
 // The kinds of a check (ADR 0536 §4): a head never judged and a head asked again after a failure of the nodes are asked on
-// the build seats' check stream, a head asked again only because its trunk moved on the recheck stream, pulled after.
+// the build seats' check stream; a carry, a verdict moved to a newer trunk or sibling commit by its package digests (ADR 0548
+// §5), on the recheck stream, pulled after.
 const (
 	KindNew   = "new"
 	KindNodes = "nodes"
 	KindTrunk = "trunk"
 )
 
-// kindOf is the kind of a case's check, read from its verdict key: none (or one left running) is a head never judged; a
-// failure of the nodes is asked again after the nodes changed; a verdict on other trunk heads is a re-judge after a trunk
-// move. A verdict that stands is ranked with the re-judges: its claim finds nothing to do.
-func (ch *Checker) kindOf(ctx context.Context, cs *Case) string {
+// prepare reads the case's verdict key and says what its check is (ADR 0548 §1, §5, §7): none (or one left running) is a
+// head never judged, a whole check; a failure of the nodes is asked again after the nodes changed; a verdict judged on trunk
+// or sibling commits that moved since is carried, its packages run only where the move changed their digest, and a pass's
+// commits are named as the carry's CarriedFrom. A verdict that stands is ranked with the carries: its claim finds nothing
+// to do.
+func (ch *Checker) prepare(ctx context.Context, cs *Case) {
+	cs.Kind, cs.CarriedFrom, cs.Composition = KindNew, nil, nil
 	value, _, found, err := ch.Verdicts.Get(ctx, cs.Key)
 	if err != nil || !found {
-		return KindNew
+		return
 	}
 	v, err := delivery.DecodeVerdict(value)
 	switch {
 	case err != nil || v.State == delivery.VerdictRunning:
-		return KindNew
+		return
 	case IsNodesFailure(v):
-		return KindNodes
+		cs.Kind = KindNodes
+		return
+	case IsConflictFailure(v):
+		return // a head git refused: its next check is whole (ADR 0548 §7)
+	case IsEnded(v), IsUntrunked(v):
+		return // ended unjudged when its heads went (issue 1890), or never judged for want of a trunk head (issue 1422): checked whole
 	}
-	return KindTrunk
+	cs.Kind = KindTrunk
+	if v.State == delivery.VerdictPass && ch.stale(v, cs) {
+		cs.CarriedFrom = judgedOn(v)
+		if c := v.Composition; c != nil && c.State == delivery.CompositionPass && c.FPSet != "" && c.FPSet == cs.FPSet {
+			kept := *c
+			cs.Composition = &kept
+		}
+	}
+}
+
+// stale says whether a verdict was judged on commits that are no longer the case's: a trunk it merged moved, or a sibling it
+// read at its trunk's head (ADR 0548 §6).
+func (ch *Checker) stale(v delivery.Verdict, cs *Case) bool {
+	return !sameTrunk(v.Trunk, cs.Trunk) || besideMoved(v.Beside, ch.besideNow())
+}
+
+// besideNow are the commits a sibling is read at now, by repository: its trunk head, and for the node-engine the commit the
+// mesh runs when the indexer names one, as besideFor places them.
+func (ch *Checker) besideNow() map[string]string {
+	return besideAt(ch.heads(), ch.Runs)
+}
+
+// besideAt places the commits a sibling is read at: the trunk heads, with the node-engine at the commit the mesh runs when
+// runs names one (ADR 0548 §6). The checker's decision and the status read the same commits through it.
+func besideAt(now map[string]string, runs interface{ CommitOf(module string) string }) map[string]string {
+	if runs != nil {
+		if c := runs.CommitOf(nodeEngineModule); c != "" {
+			out := make(map[string]string, len(now)+1)
+			for r, h := range now {
+				out[r] = h
+			}
+			out[nodeEngineRepo] = c
+			return out
+		}
+	}
+	return now
+}
+
+// besideMoved says whether a sibling read at these commits moved: the commit it is read at now is known and another.
+func besideMoved(beside, now map[string]string) bool {
+	for r, c := range beside {
+		if h := now[r]; h != "" && h != c {
+			return true
+		}
+	}
+	return false
+}
+
+// judgedOn are the trunk and sibling commits a verdict was judged on, by repository.
+func judgedOn(v delivery.Verdict) map[string]string {
+	out := make(map[string]string, len(v.Trunk)+len(v.Beside))
+	for r, c := range v.Beside {
+		out[r] = c
+	}
+	for r, c := range v.Trunk {
+		out[r] = c
+	}
+	return out
+}
+
+// carried is what a carry's verdict names as carried from (ADR 0548 §5): the commits it was judged on before, of the
+// repositories the new verdict still judges or reads; nil when none of them moved.
+func carried(from map[string]string, v delivery.Verdict) map[string]string {
+	out, moved := map[string]string{}, false
+	for r, c := range from {
+		now, ok := v.Trunk[r]
+		if !ok {
+			now, ok = v.Beside[r]
+		}
+		if ok && now != "" && c != "" {
+			out[r] = c
+			moved = moved || now != c
+		}
+	}
+	if !moved {
+		return nil
+	}
+	return out
+}
+
+// moveWords say a carry's moves, for the words of a failure: "carried from <old12> to <new12> of <repository>", each moved
+// repository, sorted.
+func moveWords(from map[string]string, v delivery.Verdict) string {
+	var moves []string
+	for r, c := range from {
+		now, ok := v.Trunk[r]
+		if !ok {
+			now = v.Beside[r]
+		}
+		if now != "" && now != c {
+			moves = append(moves, fmt.Sprintf("%s %s to %s", r, short12(c), short12(now)))
+		}
+	}
+	sort.Strings(moves)
+	return strings.Join(moves, ", ")
 }
 
 func (ch *Checker) candidate(key string, fallback delivery.Candidate) delivery.Candidate {
@@ -265,6 +622,9 @@ func (ch *Checker) claim(ctx context.Context, cs *Case, first bool, epoch uint64
 		return nil, fmt.Errorf("%s: %w", cs.Key, err)
 	}
 	if !found {
+		if ch.heldByTurn(cs) {
+			return nil, nil
+		}
 		rev, err := ch.Verdicts.Create(ctx, cs.Key, data)
 		if errors.Is(err, ErrConflict) {
 			return nil, nil // another checker made it first
@@ -285,15 +645,15 @@ func (ch *Checker) claim(ctx context.Context, cs *Case, first bool, epoch uint64
 			return &claimed{rev}, nil
 		}
 		return nil, nil
-	case !sameTrunk(cur.Trunk, cs.Trunk):
-		retake = true
+	case IsEnded(cur), ch.stale(cur, cs):
+		retake = true // heads held again after their check was ended unjudged (issue 1890), or a trunk that moved
 	case cur.State == delivery.VerdictFail && IsNodesFailure(cur):
 		ch.mu.Lock()
 		at, ok := ch.nodesFail[cs.Key]
 		ch.mu.Unlock()
 		retake = !ok || epoch > at
 	}
-	if !retake {
+	if !retake || ch.heldByTurn(cs) {
 		return nil, nil
 	}
 	rev, err = ch.Verdicts.Update(ctx, cs.Key, data, rev)
@@ -306,6 +666,59 @@ func (ch *Checker) claim(ctx context.Context, cs *Case, first bool, epoch uint64
 	return &claimed{rev}, nil
 }
 
+// heldByTurn says whether a merge turn holds the case's check off (ADR 0548 §3): an approved merge waits on one of the
+// repositories it merges heads into, and it is not the merge of the case's own heads. The check is claimed when the turn's
+// key goes (Reconsider on the turns watch). Said once per turn in the log. A check already claimed is never held: one
+// claimed in the moment before the gate wrote its turn is judged on the commit it read and carried once after.
+func (ch *Checker) heldByTurn(cs *Case) bool {
+	if ch.Turns == nil {
+		return false
+	}
+	repos := make([]string, 0, len(cs.Trunk))
+	for r := range cs.Trunk {
+		repos = append(repos, r)
+	}
+	repo, w, held := ch.Turns.Holding(repos, cs.Heads)
+	why := ""
+	if held {
+		why = repo + " " + w.Group + " " + w.Heads
+	}
+	ch.mu.Lock()
+	said := ch.held[cs.Key]
+	if why == "" {
+		delete(ch.held, cs.Key)
+	} else {
+		ch.held[cs.Key] = why
+	}
+	ch.mu.Unlock()
+	if held && said != why {
+		ch.logf("%s: not claimed: the approved merge of %s (heads %s) holds a turn on %s, so its check waits for that merge (ADR 0548 §3)",
+			cs.Key, w.Group, w.Heads, repo)
+	}
+	return held
+}
+
+// Held is every check a merge turn holds off now, by verdict key, with the turn's repository, group and heads.
+func (ch *Checker) Held() map[string]string {
+	ch.init()
+	ch.mu.Lock()
+	defer ch.mu.Unlock()
+	out := make(map[string]string, len(ch.held))
+	for k, v := range ch.held {
+		out[k] = v
+	}
+	return out
+}
+
+// ConflictWords are what the words of a head that git would not merge onto its trunk say before the files in conflict.
+const ConflictWords = "does not merge into the trunk: files in conflict: "
+
+// IsConflictFailure says whether a verdict failed because its head did not merge onto its trunk (ADR 0548 §7): it has no
+// pass to carry, so its next check, at a push or at a later trunk move, is a whole check of its head.
+func IsConflictFailure(v delivery.Verdict) bool {
+	return v.State == delivery.VerdictFail && strings.Contains(v.Failed.Words, ConflictWords)
+}
+
 // IsNodesFailure says whether a verdict failed because a part of the mesh the check reads was not heard (UnheardWords):
 // it is judged again when the nodes change. No check fails for want of a build node any more: its asks wait in the build
 // seats' streams (ADR 0525 §6, issue 1912).
@@ -313,9 +726,13 @@ func IsNodesFailure(v delivery.Verdict) bool {
 	return v.State == delivery.VerdictFail && strings.Contains(v.Failed.Words, UnheardWords)
 }
 
-// try claims the check, judges it within its bound and writes the verdict and the owed statuses. A check that ends
-// because ctx did is left running: the checker takes it again when it starts.
-func (ch *Checker) try(ctx context.Context, key string, cs *Case) {
+// try claims the check, judges it within its bound under run and writes the verdict and the owed statuses. A check that ends
+// because ctx did is left running: the checker takes it again when it starts. A check whose run was ended because no
+// candidate holds its heads any more (issue 1890) is ended: its verdict says so, and no status is written.
+func (ch *Checker) try(ctx, run context.Context, key string, cs *Case) {
+	if run.Err() != nil {
+		return // ended before it was claimed: nothing to write
+	}
 	ch.mu.Lock()
 	first := !ch.tried[cs.Key]
 	ch.tried[cs.Key] = true
@@ -330,13 +747,58 @@ func (ch *Checker) try(ctx context.Context, key string, cs *Case) {
 		return
 	}
 	began := ch.now()
+	if cs.Watch == nil && ch.Asks != nil {
+		cs.Watch = func(_ string, step *delivery.Step) {
+			if step == nil { // put: kept before its wait starts
+				ch.recordAsks(ctx, cs.Key, cs.Asks())
+			}
+		}
+		defer ch.forgetAsks(ctx, cs.Key)
+	}
 	ch.writeOwed(ctx, cs, delivery.Verdict{State: delivery.VerdictRunning}, Outcome{})
-	out := ch.judge(ctx, cs)
-	if ctx.Err() != nil {
+	out := ch.judge(run, cs)
+	// An ask the build seat gave up on, or whose step the build module's next process ended because it was replaced under
+	// it, judged nothing (issue 734, IsLostAsk): the check is asked again under the same claim, its status pending, and after
+	// LostAskTries it fails as not heard, judged again when the nodes change. A step that ended while its watch was deaf is
+	// read at the next nudge (HeardEnds) and judged.
+	for try := 1; IsLostAsk(out.Verdict) && run.Err() == nil; try++ {
+		if try >= LostAskTries {
+			out.Verdict.Failed.Words = strings.TrimSpace(out.Verdict.Failed.Words + "\nasked " + fmt.Sprint(LostAskTries) +
+				" times and given up each time: " + UnheardWords)
+			break
+		}
+		ch.logf("%s: %s; asked again (%d of %d)", cs.Key, out.Verdict.Failed.Words, try+1, LostAskTries)
+		out = ch.judge(run, cs)
+	}
+	if ctx.Err() != nil || errors.Is(context.Cause(run), errAskedAgain) {
+		return // the checker stops, or the verdict was asked again by hand, which wrote it: its next check claims it anew
+	}
+	var why superseded
+	if errors.As(context.Cause(run), &why) {
+		ch.end(ctx, cs, cl, why)
 		return
 	}
 	v := out.Verdict
-	v.Group, v.Heads, v.Trunk = cs.Group, cs.Heads, cs.Trunk
+	v.Group, v.Heads, v.Trunk, v.Beside = cs.Group, cs.Heads, cs.Trunk, nil
+	for r, c := range out.Beside {
+		if _, merged := cs.Trunk[r]; !merged && c != "" {
+			if v.Beside == nil {
+				v.Beside = map[string]string{}
+			}
+			v.Beside[r] = c
+		}
+	}
+	if cs.CarriedFrom != nil {
+		// A carry (ADR 0548 §5): a pass names the commits it was carried from; a failure names the move it failed on.
+		switch v.State {
+		case delivery.VerdictPass:
+			v.CarriedFrom = carried(cs.CarriedFrom, v)
+		case delivery.VerdictFail:
+			if moves := moveWords(cs.CarriedFrom, v); moves != "" {
+				v.Failed.Words = strings.TrimSpace(v.Failed.Words + "\nfailed on the carry over the move of " + moves + ": the move changed what these tests read")
+			}
+		}
+	}
 	if v.Took.Queue == 0 && !cs.Queued.IsZero() && began.After(cs.Queued) {
 		v.Took.Queue = began.Sub(cs.Queued).Milliseconds()
 	}
@@ -350,25 +812,50 @@ func (ch *Checker) try(ctx context.Context, key string, cs *Case) {
 		}
 	}
 	if _, err := ch.Verdicts.Update(ctx, cs.Key, data, cl.rev); err != nil {
-		ch.logf("%s: the verdict could not be written: %v", cs.Key, err)
-		return
+		if _, _, found, gerr := ch.Verdicts.Get(ctx, cs.Key); gerr == nil && !found {
+			_, err = ch.Verdicts.Create(ctx, cs.Key, data) // its key was deleted while it ran (issue 1733): written anew
+		}
+		if err != nil {
+			ch.logf("%s: the verdict could not be written: %v", cs.Key, err)
+			return
+		}
 	}
 	if IsNodesFailure(v) {
 		ch.mu.Lock()
 		ch.nodesFail[cs.Key] = epoch
 		ch.mu.Unlock()
 	}
-	if ch.movedSince(cs) {
+	if ch.movedSince(cs) || besideMoved(v.Beside, ch.besideNow()) {
 		// Judged on a trunk that moved while it ran: the verdict is kept as judged, and the status stays pending until the
 		// check of the new trunk, which Reconsider starts, ends.
-		ch.writeOwed(ctx, cs, delivery.Verdict{State: delivery.VerdictRunning}, Outcome{})
-		ch.logf("%s: %s on a trunk that moved while it ran; the status stays pending", cs.Key, v.State)
+		ch.owePending(ctx, cs, v)
+		ch.logf("%s: %s on a trunk that moved while it ran; the status stays pending until it is carried", cs.Key, v.State)
 		return
 	}
 	ch.writeOwed(ctx, cs, v, out)
 	ch.logf("%s: %s", cs.Key, v.State)
 }
 
+// end writes the verdict of a check whose heads no candidate holds any more (issue 1890), by compare-and-set on its claim,
+// and says it once in the log with the asks it had put: they stay in the build seats' streams, since an ask once put cannot
+// be taken back (buildrun.Asker has no withdraw), and are no longer waited for. No status is written: the heads that
+// replaced these have their own check, whose pending status stands.
+func (ch *Checker) end(ctx context.Context, cs *Case, cl *claimed, why superseded) {
+	v := delivery.Verdict{Group: cs.Group, Heads: cs.Heads, Trunk: cs.Trunk, State: delivery.VerdictFail,
+		Failed: delivery.FailedFirst{Machine: "checker", Words: why.Error()}}
+	data, err := delivery.EncodeVerdict(v)
+	if err == nil {
+		_, err = ch.Verdicts.Update(ctx, cs.Key, data, cl.rev)
+	}
+	if err != nil {
+		ch.logf("%s: %s, but the verdict could not say so: %v", cs.Key, why.Error(), err)
+		return
+	}
+	stage, _ := cs.Progress.Now()
+	asks := cs.Asks()
+	ch.logf("%s: %s; it was at %q with %d asks put %v, which are no longer waited for", cs.Key, why.Error(), stage, len(asks), asks)
+}
+
 // judge runs the case within the bound. A judge that fails to judge, and a check that ran past its bound, are verdicts of
 // failure naming the machine and the step.
 func (ch *Checker) judge(ctx context.Context, cs *Case) Outcome {
@@ -467,7 +954,7 @@ func (ch *Checker) Sweep(ctx context.Context) error {
 			continue
 		}
 		cur.State = delivery.VerdictFail
-		cur.Failed = delivery.FailedFirst{Machine: "checker", Words: "closed at start: left running, and no candidate holds these heads any more, so nothing will check them"}
+		cur.Failed = delivery.FailedFirst{Machine: "checker", Words: EndedWords + "closed at start: left running, and no candidate holds these heads any more, so nothing will check them"}
 		data, err := delivery.EncodeVerdict(cur)
 		if err != nil {
 			return err
@@ -502,14 +989,37 @@ func (ch *Checker) TrunkMoved(ctx context.Context) {
 		if err != nil || !found {
 			continue // never judged: no status to put out of date
 		}
-		if v, err := delivery.DecodeVerdict(value); err == nil && sameTrunk(v.Trunk, cs.Trunk) {
+		v, err := delivery.DecodeVerdict(value)
+		if err == nil && !ch.stale(v, cs) {
 			continue
 		}
+		if err == nil && v.State == delivery.VerdictPass {
+			cs.CarriedFrom = judgedOn(v) // the status says it is being carried to the new commit (ADR 0548 §6)
+		}
 		ch.writeOwed(ctx, cs, delivery.Verdict{State: delivery.VerdictRunning}, Outcome{})
 	}
 	ch.Reconsider(ctx)
 }
 
+// owePending owes mesh/check pending on the heads of a verdict judged on commits that moved while it ran: a pass says it is
+// being carried to the trunk's head now (ADR 0548 §6), anything else that it is checked again.
+func (ch *Checker) owePending(ctx context.Context, judged *Case, v delivery.Verdict) {
+	next := judged
+	ckey, err := delivery.CandidatesKey(v.Group)
+	ch.mu.Lock()
+	c, ok := ch.known[ckey]
+	ch.mu.Unlock()
+	if err == nil && ok {
+		if now := CaseOf(c, ch.heads()); now != nil && now.Key == judged.Key {
+			next = now
+		}
+	}
+	if v.State == delivery.VerdictPass {
+		next.CarriedFrom = judgedOn(v)
+	}
+	ch.writeOwed(ctx, next, delivery.Verdict{State: delivery.VerdictRunning}, Outcome{})
+}
+
 // movedSince says whether a trunk the case was judged on is no longer the trunk's head.
 func (ch *Checker) movedSince(cs *Case) bool {
 	now := ch.heads()

modules/mesh-delivery-checker/internal/check/checker_test.go

@@ -3,6 +3,7 @@ package check
 import (
 	"context"
 	"encoding/json"
+	"fmt"
 	"strings"
 	"sync"
 	"testing"
@@ -238,14 +239,119 @@ func TestAnUnheardForgeFailsWithTheReasonAndIsJudgedAgainWhenTheNodesChange(t *t
 	}
 }
 
-func TestARepositoryWithNoTrunkGetsNoVerdict(t *testing.T) { // N6/AC6, ADR 0484 clause 11
+// Issue 1422: a pull request of a repository the gate's source.main names no trunk head of (one never merged through the
+// gate) is never dropped silently. It is not judged, its verdict says it cannot be judged and why, its status is error with
+// those words, checker_status names it, and the log says it once per head. Once its trunk head is known it is judged whole;
+// in a group, the members whose trunk is known are judged and the others' status says why they are not.
+func TestARepositoryWithNoTrunkCannotBeJudgedLoudlyUntilItsTrunkIsKnown(t *testing.T) { // N6/AC6, ADR 0484 clause 11, 1422
 	ctx, j := context.Background(), passJudge()
 	r := newRig(t, j)
-	r.ch.Candidate(ctx, "feat/y", candidateOf(t, "feat/y", pullOf("novox/unknown", 4, head1)))
+	var logged []string
+	r.ch.Logf = func(f string, a ...any) { logged = append(logged, fmt.Sprintf(f, a...)) }
+	const unknown = "novox/unknown"
+	cand := candidateOf(t, "feat/y", pullOf(unknown, 4, head1))
+	key := keyOf(t, "feat/y", cand)
+	r.ch.Candidate(ctx, "feat/y", cand)
 	r.ch.Wait()
-	if j.count() != 0 || len(r.verdicts.vals) != 0 || len(r.owed.vals) != 0 {
-		t.Errorf("judged %d times, %d verdicts, %d statuses, want none", j.count(), len(r.verdicts.vals), len(r.owed.vals))
+	r.ch.Reconsider(ctx) // looked at again: nothing is written or said twice
+	r.ch.NodesChanged(ctx)
+	r.ch.Wait()
+	v := r.verdict(t, key)
+	if j.count() != 0 || !IsUntrunked(v) || !strings.Contains(v.Failed.Words, "the trunk head of "+unknown+" is not known") {
+		t.Fatalf("judged %d times, verdict %+v, want none judged and a verdict that says it cannot be judged", j.count(), v)
 	}
+	if s := owedState(t, r, unknown, 4, head1); s != "error" {
+		t.Errorf("%s#4 owes %q, want error", unknown, s)
+	}
+	if n := countWith(logged, "cannot be judged"); n != 1 {
+		t.Errorf("said %d times in the log, want once for the head: %q", n, logged)
+	}
+	reader := func() Reader {
+		ckey, _ := delivery.CandidatesKey("feat/y")
+		return Reader{CandidateState: fakeState{ckey: cand}.read(), VerdictState: fakeState(r.verdicts.vals).read(),
+			Trunks: func() (map[string]string, error) { return r.trunks.Heads(), nil }}
+	}
+	st, err := reader().Status()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if why := st.CannotBeJudged["feat/y"]; !strings.Contains(why, unknown) || len(st.Waiting[KindNew]) != 0 || len(st.Unjudged) != 0 {
+		t.Errorf("cannot_be_judged %v, waiting %v, unjudged %v: want feat/y named as cannot be judged, not as new", st.CannotBeJudged, st.Waiting, st.Unjudged)
+	}
+	if rows, _, err := reader().Verdicts("feat/y"); err != nil || len(rows) != 1 || !strings.Contains(rows[0].Reports[unknown+"#4"], "cannot be judged") {
+		t.Errorf("checker_verdicts %+v (%v), want the report of %s#4 to say it cannot be judged", rows, err, unknown)
+	}
+
+	// Its trunk head becomes known: the heads are judged whole, the same key rewritten, the status success.
+	r.setTrunks(t, map[string]string{repoA: trunkA, repoSDK: trunkS, unknown: trunkA2})
+	r.ch.TrunkMoved(ctx)
+	r.ch.Wait()
+	if v := r.verdict(t, key); j.count() != 1 || v.State != delivery.VerdictPass || v.Trunk[unknown] != trunkA2 {
+		t.Errorf("judged %d times, verdict %+v, want one pass on %s", j.count(), v, trunkA2)
+	}
+	if s := owedState(t, r, unknown, 4, head1); s != "success" {
+		t.Errorf("%s#4 owes %q once its trunk is known, want success", unknown, s)
+	}
+
+	// Issue 1733: the gate asks the Approve only on a verdict, so no candidate is left without one. A group with a member
+	// whose trunk is not known is not judged in part: its verdict fails naming that repository, and every status says so; a
+	// running verdict left for heads that cannot be judged is replaced; a verdict key deleted is judged again on its delete.
+	for _, row := range []struct {
+		name    string
+		pulls   []delivery.CandidatePull
+		running bool // a running verdict is left under the key first
+		deleted bool // the key is deleted after its verdict
+		judged  int
+		want    string // the verdict's state, and for a failure the repository it names
+	}{
+		{name: "a member the checker cannot claim", pulls: []delivery.CandidatePull{pullOf(repoA, 9, head2), pullOf("novox/other", 2, head2)}, want: "novox/other"},
+		{name: "a running verdict left for heads that cannot be judged", pulls: []delivery.CandidatePull{pullOf(unknown, 5, head2)}, running: true, want: unknown},
+		{name: "a verdict key deleted", pulls: []delivery.CandidatePull{pullOf(repoA, 5, head2)}, deleted: true, judged: 2, want: delivery.VerdictPass},
+	} {
+		t.Run(row.name, func(t *testing.T) {
+			j := passJudge()
+			r := newRig(t, j)
+			cand := candidateOf(t, "feat/z", row.pulls...)
+			key := keyOf(t, "feat/z", cand)
+			if row.running {
+				group, heads, _ := delivery.ParseCheckerVerdictKey(key)
+				raw, _ := delivery.EncodeVerdict(delivery.Verdict{Group: group, Heads: heads, State: delivery.VerdictRunning})
+				_, _ = r.verdicts.Create(ctx, key, raw)
+			}
+			r.ch.Candidate(ctx, "feat%2Fz", cand)
+			r.ch.Wait()
+			if row.deleted {
+				_ = r.verdicts.Delete(ctx, key)
+				r.ch.VerdictDeleted(ctx, key) // the watch of the verdicts hands the delete over
+				r.ch.Wait()
+			}
+			v := r.verdict(t, key)
+			if row.want == delivery.VerdictPass {
+				if v.State != delivery.VerdictPass || j.count() != row.judged {
+					t.Errorf("verdict %s after %d judgings, want a pass after %d", v.State, j.count(), row.judged)
+				}
+				return
+			}
+			if !IsUntrunked(v) || !strings.Contains(v.Failed.Words, row.want) || j.count() != 0 {
+				t.Errorf("verdict %+v after %d judgings, want a failure naming %s and none judged", v, j.count(), row.want)
+			}
+			for _, p := range row.pulls {
+				if s := owedState(t, r, p.Repository, p.Number, p.Head.Head); s != "error" {
+					t.Errorf("%s#%d owes %q, want error", p.Repository, p.Number, s)
+				}
+			}
+		})
+	}
+}
+
+func countWith(lines []string, words string) int {
+	n := 0
+	for _, l := range lines {
+		if strings.Contains(l, words) {
+			n++
+		}
+	}
+	return n
 }
 
 // 1887/A10, ADR 0527 §2: hq is judged as any repository, its checks Go tests, and its pull request gets a verdict and a
@@ -333,7 +439,10 @@ func TestTheStatusIsPendingWhileTheCheckRunsAndEndsSuccessOrFailure(t *testing.T
 	}
 }
 
-func TestSweepClosesARunningKeyNoCandidateHoldsAndLeavesOneItDoes(t *testing.T) {
+// No check of heads no candidate holds is left running (issue 1890): at start the sweep ends a key left running; while the
+// checker runs, a check whose group moved to other heads is ended at once, unjudged, and writes no status; heads held again
+// are checked whole; and a group's check starts only once its heads settled, so a partial set of members is never checked.
+func TestHeadsNoCandidateHoldsAreNeverLeftRunning(t *testing.T) {
 	ctx, j := context.Background(), passJudge()
 	r := newRig(t, j)
 	cand := candidateOf(t, "feat/x", pullOf(repoA, 7, head1))
@@ -351,12 +460,91 @@ func TestSweepClosesARunningKeyNoCandidateHoldsAndLeavesOneItDoes(t *testing.T)
 	if err := r.ch.Sweep(ctx); err != nil {
 		t.Fatal(err)
 	}
-	if v := r.verdict(t, dead); v.State != delivery.VerdictFail || !strings.Contains(v.Failed.Words, "closed at start") {
+	if v := r.verdict(t, dead); !IsEnded(v) || !strings.Contains(v.Failed.Words, "closed at start") {
 		t.Errorf("the dead key = %+v", v)
 	}
 	if v := r.verdict(t, live); v.State != delivery.VerdictRunning {
 		t.Errorf("the live key = %+v, want it left for the check to take over", v)
 	}
+
+	// A member joins while the check of the lone member's heads runs: that check is ended, its judge's run cancelled.
+	started, ended := make(chan struct{}), make(chan error, 1)
+	j = &judgeFunc{f: func(run context.Context, _ *Case, call int) (Outcome, error) {
+		if call == 1 {
+			close(started)
+			<-run.Done()
+			ended <- context.Cause(run)
+			return Outcome{}, run.Err()
+		}
+		return Outcome{Verdict: passing()}, nil
+	}}
+	r = newRig(t, j)
+	var logged []string
+	var logMu sync.Mutex
+	r.ch.Logf = func(f string, a ...any) { logMu.Lock(); logged = append(logged, fmt.Sprintf(f, a...)); logMu.Unlock() }
+	alone, both := cand, candidateOf(t, "feat/x", pullOf(repoA, 7, head1), pullOf(repoSDK, 3, head2))
+	r.ch.Candidate(ctx, "feat%2Fx", alone)
+	<-started
+	r.ch.Candidate(ctx, "feat%2Fx", both)
+	var bothC delivery.Candidate
+	_ = json.Unmarshal(both, &bothC)
+	select {
+	case err := <-ended:
+		if err == nil || !strings.Contains(err.Error(), "superseded by "+GateHeads(bothC)) {
+			t.Errorf("the old check's run ended with %v", err)
+		}
+	case <-time.After(5 * time.Second):
+		t.Fatal("the check of the heads the candidate left still runs")
+	}
+	r.ch.Wait()
+	if v := r.verdict(t, live); !IsEnded(v) || v.Failed.Words != EndedWords+"superseded by "+GateHeads(bothC) {
+		t.Errorf("the superseded verdict = %+v", v.Failed)
+	}
+	if v := r.verdict(t, keyOf(t, "feat/x", both)); v.State != delivery.VerdictPass {
+		t.Errorf("the group's verdict = %s", v.State)
+	}
+	okey, _ := delivery.CheckerOwedKey(repoA, 7, head1)
+	if raw, _, _, _ := r.owed.Get(ctx, okey); !strings.Contains(string(raw), `"success"`) {
+		t.Errorf("the head's status = %s, want the group's success, never the ended check's", raw)
+	}
+	logMu.Lock()
+	said := 0
+	for _, l := range logged {
+		if strings.Contains(l, "ended: superseded") {
+			said++
+		}
+	}
+	logMu.Unlock()
+	if said != 1 {
+		t.Errorf("the end was said %d times: %v", said, logged)
+	}
+	// The member leaves again: the ended heads are held again and checked whole.
+	r.ch.Candidate(ctx, "feat%2Fx", alone)
+	r.ch.Wait()
+	if v := r.verdict(t, live); v.State != delivery.VerdictPass || j.count() != 3 {
+		t.Errorf("the heads held again = %s after %d judgings, want a pass of a third", v.State, j.count())
+	}
+
+	// Members announced one after another: only the settled, whole set is checked.
+	j = passJudge()
+	r = newRig(t, j)
+	r.ch.Settle = time.Hour
+	sdk := candidateOf(t, "feat/y", pullOf(repoSDK, 4, head2))
+	whole := candidateOf(t, "feat/y", pullOf(repoSDK, 4, head2), pullOf(repoA, 8, head1))
+	r.ch.Candidate(ctx, "feat%2Fy", sdk)
+	r.ch.Candidate(ctx, "feat%2Fy", whole)
+	r.ch.Reconsider(ctx) // a trunk move or a turn while the heads settle starts nothing
+	if j.count() != 0 {
+		t.Fatalf("judged %d times before the heads settled", j.count())
+	}
+	r.ch.settleNow()
+	r.ch.Wait()
+	if _, _, found, _ := r.verdicts.Get(ctx, keyOf(t, "feat/y", sdk)); found || j.count() != 1 {
+		t.Errorf("the partial set has a verdict (%v) or the judge ran %d times, want the whole set alone", found, j.count())
+	}
+	if v := r.verdict(t, keyOf(t, "feat/y", whole)); v.State != delivery.VerdictPass {
+		t.Errorf("the whole set = %s", v.State)
+	}
 }
 
 func TestTheForgeBridgeIsToldOnceForEachChangeOfAStatus(t *testing.T) { // 1683 (the checker's half of AC5)

modules/mesh-delivery-checker/internal/check/composition_test.go

@@ -28,6 +28,7 @@ func TestAPassingCheckTakesTheAssignersComposition(t *testing.T) {
 	f := &fakeCompositions{v: delivery.CompositionVerdict{Group: "feat/x", Heads: "0123456789ab", State: delivery.CompositionPass, SDK: "v0.1.14-x", Machines: []string{"g14"}, Took: 40}}
 	b.ex.Compositions = f
 	cs := caseOf(t, pullOf(repoA, 7, head1))
+	cs.FPSet = "fps-of-the-candidate"
 	v := b.judge(t, cs).Verdict
 	if v.State != delivery.VerdictPass || v.Composition == nil || v.Composition.State != delivery.CompositionPass || v.Composition.SDK != "v0.1.14-x" || v.Took.Composition != 40 {
 		t.Fatalf("verdict = %+v, composition %+v", v, v.Composition)
@@ -38,6 +39,15 @@ func TestAPassingCheckTakesTheAssignersComposition(t *testing.T) {
 	if !compositionMentions(v, "passed") {
 		t.Errorf("the line says %q", compositionWords(v.Composition, v.Took.Composition))
 	}
+	if v.Composition.FPSet == "" || v.Composition.FPSet != cs.FPSet {
+		t.Errorf("the composition names the fingerprint set %q, want the candidate's %q (ADR 0548 §5)", v.Composition.FPSet, cs.FPSet)
+	}
+	// ADR 0548 §5: a carry whose fingerprints did not change keeps the composition it passed and asks the assigner nothing.
+	carry := caseOf(t, pullOf(repoA, 7, head1))
+	carry.CarriedFrom, carry.Composition = map[string]string{repoA: trunkA2}, v.Composition
+	if kept := b.judge(t, carry).Verdict; kept.Composition == nil || kept.Composition.SDK != "v0.1.14-x" || len(f.asked) != 1 {
+		t.Errorf("the carry's composition is %+v and the assigner was asked %d times; want the kept one and no second ask", kept.Composition, len(f.asked))
+	}
 }
 
 func compositionMentions(v delivery.Verdict, word string) bool {

modules/mesh-delivery-checker/internal/check/every_failure_test.go

@@ -0,0 +1,90 @@
+package check
+
+import (
+	"encoding/json"
+	"fmt"
+	"strings"
+	"testing"
+
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+)
+
+// failingResult is a level's test result in which the named tests failed, each in its own package.
+func failingResult(t *testing.T, tests int, failed ...Failure) json.RawMessage {
+	t.Helper()
+	raw, err := json.Marshal(Tested{Level: delivery.LevelIntegration, Tests: tests, Elapsed: 2, Failed: failed, Passed: len(failed) == 0})
+	if err != nil {
+		t.Fatal(err)
+	}
+	return raw
+}
+
+func judgeLevel(t *testing.T, tests ...json.RawMessage) (*delivery.Verdict, *state) {
+	t.Helper()
+	st := &state{j: &Examiner{}, c: &Case{}, levels: map[string]*acc{delivery.LevelUnit: {}, delivery.LevelIntegration: {}}, nodes: map[string]bool{}}
+	v, _ := st.level(t.Context(), &target{pull: Pull{Repository: "novox/x"}}, delivery.LevelAnswer{Level: delivery.LevelIntegration, Tests: tests})
+	return v, st
+}
+
+// Issue 1921: two failing tests in two packages are two entries of the verdict's Failures and two lines of a try's
+// failed list, each with its own first line (its cause, issue 1901), whether the build module answered them in one test
+// result (one go test run over both packages) or in two (the changed packages first, then the rest); every result is
+// counted, the ones after a failure too; and Failed keeps the first one's words whole.
+func TestTwoFailingTestsInTwoPackagesAreTwoEntries(t *testing.T) {
+	a := Failure{Package: "x/a", Test: "TestA", Cause: "a_test.go:9: want 1, got 2", Output: "    a_test.go:3: logged\n    a_test.go:9: want 1, got 2\n--- FAIL: TestA (0.00s)"}
+	b := Failure{Package: "x/b", Test: "TestB", Cause: "b_test.go:4: boom", Output: "    b_test.go:4: boom\n--- FAIL: TestB (0.00s)"}
+	for name, tests := range map[string][]json.RawMessage{
+		"one result":  {failingResult(t, 10, a, b)},
+		"two results": {failingResult(t, 4, a), failingResult(t, 3), failingResult(t, 3, b)},
+	} {
+		v, st := judgeLevel(t, tests...)
+		if v == nil {
+			t.Fatalf("%s: the level passed", name)
+		}
+		want := []string{"integration: x/a.TestA: a_test.go:9: want 1, got 2", "integration: x/b.TestB: b_test.go:4: boom"}
+		if got := failedLines(*v); strings.Join(got, "\n") != strings.Join(want, "\n") {
+			t.Errorf("%s: failed lines\n%s\nwant\n%s", name, strings.Join(got, "\n"), strings.Join(want, "\n"))
+		}
+		if len(v.Failures) != 2 || v.Failed.Test != "integration: x/a.TestA" || !strings.Contains(v.Failed.Words, "a_test.go:3: logged") {
+			t.Errorf("%s: verdict %+v", name, v)
+		}
+		if run := st.levels[delivery.LevelIntegration].run; run != 10 {
+			t.Errorf("%s: %d tests counted, want all 10", name, run)
+		}
+		if _, err := delivery.EncodeVerdict(delivery.Verdict{Group: "g", Heads: "0123456789ab", State: v.State, Failed: v.Failed, Failures: v.Failures}); err != nil {
+			t.Errorf("%s: the verdict is not written: %v", name, err)
+		}
+	}
+}
+
+// Issue 1921: past delivery.MaxFailures the list names the first fifty and how many more, the status line says how many
+// failed, and each entry's line is cut to MaxFailureLine.
+func TestFailuresAreCappedWithHowManyMore(t *testing.T) {
+	var fs []Failure
+	for i := range 60 {
+		fs = append(fs, Failure{Package: fmt.Sprintf("x/p%d", i), Test: "TestT", Cause: strings.Repeat("y", 500)})
+	}
+	v, _ := judgeLevel(t, failingResult(t, 60, fs...))
+	if len(v.Failures) != delivery.MaxFailures+1 || v.Failures[delivery.MaxFailures].Test != "and 10 more" {
+		t.Fatalf("%d entries, last %+v", len(v.Failures), v.Failures[len(v.Failures)-1])
+	}
+	if len(v.Failures[0].Words) > MaxFailureLine {
+		t.Errorf("an entry's line is %d bytes", len(v.Failures[0].Words))
+	}
+	if n := failedCount(*v); n != 60 {
+		t.Errorf("failedCount = %d, want 60", n)
+	}
+	cs := &Case{Pulls: []Pull{{Repository: "novox/x", Head: "0123456789abcdef", Trunk: "fedcba9876543210"}}}
+	if line := Line(*v, cs, cs.Pulls[0], nil, nil, nil); !strings.HasPrefix(line, "failed (60 tests): integration: x/p0.TestT") {
+		t.Errorf("line %q", line)
+	}
+}
+
+// A verdict that names no list (a conflict, a refused step, a verdict written before issue 1921) is one failed line, as
+// before.
+func TestAVerdictWithoutFailuresIsOneLine(t *testing.T) {
+	v := delivery.Verdict{State: delivery.VerdictFail, Failed: delivery.FailedFirst{Machine: "g14", Words: "files in conflict: go.mod\nmore"}}
+	if got := failedLines(v); len(got) != 1 || got[0] != "g14: files in conflict: go.mod" {
+		t.Fatalf("%q", got)
+	}
+}

modules/mesh-delivery-checker/internal/check/examiner_test.go

@@ -5,6 +5,7 @@ import (
 	"crypto/sha256"
 	"encoding/hex"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"os"
 	"path/filepath"
@@ -116,6 +117,9 @@ type bench struct {
 	fetch  Fetched
 	digest map[string]Digested // by level
 	test   func(c stepCall) (any, error)
+	// declines is how many asks naming needs a node lacking them declines before shanks, which has every need, takes
+	// one (issue 890); an ask naming none runs on shanks, which then has none.
+	declines int
 }
 
 // refsOf reads the siblings of a fetch's arguments, as they arrive in an ask (JSON) or as the checker gave them.
@@ -151,8 +155,17 @@ func (b *bench) answer(a delivery.StepAsk) delivery.Step {
 	if module == buildrun.GoBuildModule {
 		steps.Digest = tool("digest")
 	}
-	out, err := buildstep.RunAsk(context.Background(), steps, a)
 	began := time.Date(2026, 10, 21, 19, 0, 0, 0, time.UTC)
+	if len(a.Needs) > 0 {
+		if b.declines > 0 {
+			b.declines--
+			result, _ := json.Marshal(delivery.StepDeclined{Declined: true, Needs: a.Needs, Lacks: a.Needs})
+			return delivery.Step{ID: a.ID, Tool: a.Kind + " ask", Node: "ace", State: delivery.StepRefused, Started: began, Ended: began,
+				Reason: "declined", Result: result}
+		}
+		steps.Has = func(string) bool { return true }
+	}
+	out, err := buildstep.RunAsk(context.Background(), steps, a)
 	step := delivery.Step{ID: a.ID, Tool: a.Kind + " ask", Node: node, State: delivery.StepPassed, Started: began, Ended: began.Add(2 * time.Second)}
 	if err != nil {
 		step.State, step.Reason = delivery.StepFailed, err.Error()
@@ -260,8 +273,36 @@ func TestACleanMergeIsFetchedAtItsTrunkAndBothLevelsPass(t *testing.T) { // 1679
 			t.Errorf("%s was not kept", k)
 		}
 	}
+
+	// ADR 0567 §12: every check ask carries every node's name for the names check; a check whose names cannot be read, or
+	// that reads none, is not asked and fails saying so.
+	for _, c := range []struct {
+		names []string
+		err   error
+		fails string
+	}{{[]string{"anchor", "laptop"}, nil, ""}, {nil, nil, "no node record"}, {nil, errors.New("no bucket"), "no bucket"}} {
+		b := newBench(t)
+		b.ex.Nodes = namesOf{c.names, c.err}
+		out := b.judge(t, caseOf(t, pullOf(repoA, 7, head1)))
+		asks := b.asks.Asks()
+		if c.fails != "" {
+			if out.Verdict.State != delivery.VerdictFail || len(asks) != 0 || !strings.Contains(out.Verdict.Failed.Words, c.fails) {
+				t.Errorf("names %v, %v: verdict %+v, %d asks", c.names, c.err, out.Verdict, len(asks))
+			}
+		} else if len(asks) == 0 || strings.Join(asks[0].Check.NodeNames, ",") != "anchor,laptop" {
+			t.Errorf("the check ask carries the names %v", asks)
+		}
+	}
 }
 
+// namesOf is the nodes' names as a test gives them.
+type namesOf struct {
+	names []string
+	err   error
+}
+
+func (n namesOf) Names(context.Context) ([]string, error) { return n.names, n.err }
+
 func TestOnlyThePackageWithoutAKeptVerdictRuns(t *testing.T) { // 1288/AC1
 	b := newBench(t)
 	b.digest[delivery.LevelUnit] = Digested{Level: "unit", Packages: map[string]string{"fixture/slow": digA, "fixture/other": digC}}
@@ -276,6 +317,49 @@ func TestOnlyThePackageWithoutAKeptVerdictRuns(t *testing.T) { // 1288/AC1
 	if u := out.Verdict.Levels[delivery.LevelUnit]; u.Run != 2 || u.Kept != 40 {
 		t.Errorf("unit = %+v, want 2 run and 40 kept", u)
 	}
+
+	// Issue 890/AC5: a package needing node-build-node is left unmet where the node lacks it; the check keeps the passes
+	// and asks the integration level again for a node with it, puts it again when a node declines it, and that node tests
+	// the package alone, its kept passes not counted twice.
+	// fixture/outside has no kept verdict after its pass (it reads outside itself: its digest moves every call), so a
+	// placed ask that ran more than its unmet packages would run and count it again.
+	b = newBench(t)
+	b.declines = 1
+	outside := 0
+	b.steps.handlers["build_go_digest"] = func(c stepCall) (any, error) {
+		d := echoBeside(b, b.digest[c.args["level"].(string)])
+		if d.Level == "integration" {
+			outside++
+			d.Packages = map[string]string{"fixture/slow": digB, "fixture/node": digC, "fixture/outside": fmt.Sprintf("%064x", outside)}
+		}
+		return d, nil
+	}
+	b.digest[delivery.LevelIntegration] = Digested{Level: "integration",
+		Needs: []delivery.PackageNeeds{{Package: "fixture/node", Needs: []string{delivery.NeedNodeBuildNode}}}}
+	out = b.judge(t, caseOf(t, pullOf(repoA, 7, head1)))
+	asks := b.asks.Asks()
+	if out.Verdict.State != delivery.VerdictPass || len(asks) != 3 || len(asks[0].Needs) != 0 {
+		t.Fatalf("verdict %+v, asks %+v: want a pass of three asks, the first naming no need", out.Verdict, asks)
+	}
+	for _, a := range asks[1:] {
+		if strings.Join(a.Needs, ",") != delivery.NeedNodeBuildNode || strings.Join(a.Check.Levels, ",") != delivery.LevelIntegration || strings.Join(a.Check.Packages, ",") != "fixture/node" {
+			t.Errorf("a placed ask %+v, want the integration level needing node-build-node", a)
+		}
+	}
+	tests = b.steps.tool("test")
+	if last := tests[len(tests)-1]; len(tests) != 3 || strings.Join(packagesOf(last), ",") != "fixture/node" || last.args["level"] != "integration" {
+		t.Errorf("test calls = %+v, want the unit level, the integration level of fixture/slow and fixture/outside, then fixture/node alone", tests)
+	}
+	slow := captured[Tested](t, "go-test-slow")
+	if i := out.Verdict.Levels[delivery.LevelIntegration]; i.Run != 2*slow.Tests || i.Kept != 0 {
+		t.Errorf("integration = %+v, want %d run and nothing counted kept", i, 2*slow.Tests)
+	}
+	// And where no node has the need, the check fails once the declines outlast the bound, naming the need.
+	b.kept, b.declines = newMemKV(), 1000
+	b.ex.Kept, b.ex.DeclineBound = Kept{Store: b.kept}, 200*time.Millisecond
+	if v := b.judge(t, caseOf(t, pullOf(repoA, 7, head1))).Verdict; v.State != delivery.VerdictFail || !strings.Contains(fmt.Sprint(v), "needs a node with node-build-node") {
+		t.Errorf("with no node having the need: %+v", v)
+	}
 }
 
 func TestAReAskRunsOnlyWhatFailedAndWhatChanged(t *testing.T) { // 1288/AC2, AC3
@@ -341,7 +425,9 @@ func TestANodePackageIsNeverKeptAndRunsEveryCheck(t *testing.T) { // 1288/AC4, 1
 	}
 }
 
-func TestTheChangesOwnFailingTestRunsFirstAndNothingElseRuns(t *testing.T) { // 1289/AC1, AC2
+// 1289/AC1, AC2 as issue 1921 changed it: the change's own failing test runs first, the level's other packages still run
+// after it (so one check names every failure), and no later level runs.
+func TestTheChangesOwnFailingTestRunsFirstThenTheRestAndNoLaterLevel(t *testing.T) {
 	b := newBench(t)
 	b.fetch.Changed = []string{"modules/m/internal/b/b_test.go"}
 	b.digest[delivery.LevelUnit] = Digested{Level: "unit", Packages: map[string]string{"m/internal/a": digA, "m/internal/b": digB}}
@@ -357,8 +443,8 @@ func TestTheChangesOwnFailingTestRunsFirstAndNothingElseRuns(t *testing.T) { //
 		t.Fatalf("verdict = %+v", out.Verdict)
 	}
 	tests := b.steps.tool("test")
-	if len(tests) != 1 || strings.Join(packagesOf(tests[0]), ",") != "m/internal/b" {
-		t.Fatalf("test calls = %+v, want only m/internal/b, once", tests)
+	if len(tests) != 2 || strings.Join(packagesOf(tests[0]), ",") != "m/internal/b" || strings.Join(packagesOf(tests[1]), ",") != "m/internal/a" {
+		t.Fatalf("test calls = %+v, want m/internal/b, then m/internal/a, each once", tests)
 	}
 	if n := len(b.steps.tool("digest")); n != 1 {
 		t.Errorf("%d digest calls, want the unit level's alone (the check stopped)", n)
@@ -618,9 +704,8 @@ func TestNothingIsKeptForAWorkspaceGivenSiblingsWhenTheDigestDoesNotSayItCoversT
 // Beside): every check now places the change's own repository at its trunk (issue 1887 A12).
 func echoBeside(b *bench, d Digested) Digested {
 	var lines []string
-	for _, f := range b.steps.tool("fetch") {
-		refs, _ := refsOf(f.args["beside"]), true
-		for _, r := range refs {
+	if fetches := b.steps.tool("fetch"); len(fetches) > 0 { // the workspace digested is the last fetch's (issue 890: a placed ask fetches again)
+		for _, r := range refsOf(fetches[len(fetches)-1].args["beside"]) {
 			lines = append(lines, r.Repository+" "+r.Commit)
 		}
 	}

modules/mesh-delivery-checker/internal/check/failure_words_test.go

@@ -42,7 +42,7 @@ func TestTheStatusLineNamesTheFailureNotTheFirstLoggedLine(t *testing.T) { // 19
 	f := fatalAfterLog()
 	f.Cause = ""
 	v = levelFailure(&target{}, "unit", Tested{Failed: []Failure{f}})
-	if !strings.HasPrefix(v.Failed.Words, "agreement_catalogue_test.go:130") {
+	if !strings.HasPrefix(afterHid(v.Failed.Words), "agreement_catalogue_test.go:130") {
 		t.Errorf("words = %q", v.Failed.Words)
 	}
 }
@@ -56,18 +56,45 @@ func TestWordsLongerThanTheBoundKeepTheirLastLines(t *testing.T) { // 1901/AC1
 	_ = delivery.VerdictFail
 }
 
-// An older build module sends no "cause": its answer is still accepted and the verdict's words are its output, as before.
-func TestAnOlderBuildModulesFailureIsAcceptedWithItsWholeOutput(t *testing.T) { // 1901/AC3
+// An older build module sends no "cause": its answer is still accepted and the verdict's words are its output, as before
+// (1901/AC3). A failure that hides its cause (none, or a passing line) is said loudly first in the words and in the status
+// line, naming the build module and the version it says it is, and the level still fails; a failure that keeps the
+// contract is worded as before (1901/AC8).
+func TestAnOlderBuildModulesFailureIsAcceptedWithItsWholeOutput(t *testing.T) { // 1901/AC3, AC8
 	old := `{"package":"p","test":"TestX","output":"x_test.go:1: logged\nx_test.go:2: the old kept lines"}`
 	var f Failure
 	if err := json.Unmarshal([]byte(old), &f); err != nil || f.Cause != "" {
 		t.Fatalf("1901/AC3: err = %v, cause = %q", err, f.Cause)
 	}
 	v := levelFailure(&target{}, "unit", Tested{Failed: []Failure{f}})
-	if v.Failed.Words != "x_test.go:1: logged\nx_test.go:2: the old kept lines" {
+	if afterHid(v.Failed.Words) != "x_test.go:1: logged\nx_test.go:2: the old kept lines" {
 		t.Errorf("1901/AC3: words = %q", v.Failed.Words)
 	}
-	if got := firstFailed(*v); !strings.Contains(got, "logged") || strings.Contains(got, "\n") {
-		t.Errorf("1901/AC3: status = %q", got)
+	if got := firstFailed(*v); !strings.Contains(got, "the build module hid the failure") || strings.Contains(got, "\n") {
+		t.Errorf("1901/AC3, AC8: status = %q", got)
+	}
+
+	by := "mesh-build-node with mesh-sdk v0.1.14-0.20261026184535-e40dd0f56a78"
+	for _, c := range []struct {
+		name, module, by, cause, output, loud string
+	}{
+		{"no cause", "mesh-build-node", by, "", "test/b.test.ts: something", "the build module hid the failure (mesh-build-node at mesh-sdk v0.1.14-0.20261026184535-e40dd0f56a78): it sent no cause"},
+		{"a passing line as its cause", "mesh-build-node", by, "\u2714 the same merge has the same id (8.006913ms)", "", "the build module hid the failure (mesh-build-node at mesh-sdk v0.1.14-0.20261026184535-e40dd0f56a78): its cause is a passing line"},
+		{"from before the contract", "mesh-build-node", "", "", "\u2714 the same merge has the same id (8.006913ms)", "the build module hid the failure (mesh-build-node at a version before the failure contract): it sent no cause"},
+		{"a real cause", "mesh-build-node", by, "one plus one is not three", "not ok 3 - fails", ""},
+	} {
+		t.Run(c.name, func(t *testing.T) {
+			v := levelFailure(&target{module: c.module}, "unit", Tested{By: c.by, Failed: []Failure{{Package: "modules/gitea", Test: "fails", Cause: c.cause, Output: c.output}}})
+			if v.State != delivery.VerdictFail {
+				t.Errorf("1901/AC8: the verdict is %q, want it failed", v.State)
+			}
+			line := firstFailed(*v)
+			switch {
+			case c.loud == "" && strings.Contains(v.Failed.Words, "hid the failure"):
+				t.Errorf("1901/AC8: a failure that keeps the contract is said hidden: %q", v.Failed.Words)
+			case c.loud != "" && (!strings.HasPrefix(v.Failed.Words, c.loud) || !strings.Contains(line, c.loud) || !strings.Contains(v.Failures[0].Words, "hid the failure")):
+				t.Errorf("1901/AC8: words %q, status %q, want both to start with %q", v.Failed.Words, line, c.loud)
+			}
+		})
 	}
 }

modules/mesh-delivery-checker/internal/check/fakes_test.go

@@ -60,3 +60,11 @@ func (m *memKV) Keys(context.Context) ([]string, error) {
 	sort.Strings(keys)
 	return keys, nil
 }
+
+func (m *memKV) Delete(_ context.Context, key string) error {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	delete(m.vals, key)
+	delete(m.revs, key)
+	return nil
+}

modules/mesh-delivery-checker/internal/check/gate_test.go

@@ -4,7 +4,6 @@ import (
 	"context"
 	"strings"
 	"testing"
-	"time"
 
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 )
@@ -88,29 +87,3 @@ func TestATrunkMoveMarksEveryOpenPullRequestIntoItPendingAtOnce(t *testing.T) {
 		t.Errorf("mesh-sdk#13, alone into a trunk that did not move, is %q, want its success to stand", s)
 	}
 }
-
-func TestACheckThatEndsAfterItsTrunkMovedOwesPendingNotItsVerdict(t *testing.T) { // gate (a): a pass on an old trunk is never shown
-	ctx := context.Background()
-	var r *rig
-	release, judged := make(chan struct{}), make(chan struct{})
-	j := &judgeFunc{f: func(ctx context.Context, c *Case, call int) (Outcome, error) {
-		if call == 1 {
-			r.setTrunks(t, map[string]string{repoA: trunkA2, repoSDK: trunkS}) // the trunk moves while it runs
-			defer close(judged)
-		} else {
-			<-release // the check asked again for the new trunk waits in the stream meanwhile
-		}
-		return Outcome{Verdict: passing()}, nil
-	}}
-	r = newRig(t, j)
-	r.ch.Candidate(ctx, "feat%2Fx", candidateOf(t, "feat/x", pullOf(repoA, 7, head1)))
-	<-judged
-	for deadline := time.Now().Add(2 * time.Second); owedState(t, r, repoA, 7, head1) == "" && time.Now().Before(deadline); time.Sleep(time.Millisecond) {
-	}
-	time.Sleep(20 * time.Millisecond)
-	if s := owedState(t, r, repoA, 7, head1); s != "pending" {
-		t.Errorf("the status is %q, want pending: the pass was judged on a trunk that moved", s)
-	}
-	close(release)
-	r.ch.Wait()
-}

modules/mesh-delivery-checker/internal/check/judge.go

@@ -80,6 +80,9 @@ var askLanguage = map[string]string{buildrun.GoBuildModule: delivery.AskGo, buil
 // stopping at the first failure; it judges the step's answer as it judged the tools' answers.
 type Examiner struct {
 	Asks Asks
+	// DeclineBound is how long a placed ask may go on being declined, from its first decline, before the check fails
+	// saying no node with its need took it (issue 890, ADR 0552); DefaultDeclineBound when zero.
+	DeclineBound time.Duration
 	// Toolchains are the nodes' toolchains: a kept verdict names the toolchain the nodes agree on.
 	Toolchains ToolchainEntries
 	Kept       Kept
@@ -107,8 +110,14 @@ type Examiner struct {
 	// waiting until the assigner wrote a verdict that does not wait, or ctx ends (ADR 0528 clause 5, issue 1297); nil
 	// leaves the composition not run.
 	Compositions CompositionReader
-	Now          func() time.Time
-	Logf         func(format string, args ...any)
+	// Nodes names every node with a record, read from each `<node>.node` of the node-engine's have (novox/hq ADR 0567
+	// §12): every check ask carries them (CheckJob.NodeNames) for the names check, so no repository lists them. A check
+	// whose names cannot be read, or that reads none, is not asked and fails saying so; nil hands no names.
+	Nodes interface {
+		Names(ctx context.Context) ([]string, error)
+	}
+	Now  func() time.Time
+	Logf func(format string, args ...any)
 }
 
 // CompositionReader answers the assigner's composition of a check by the check's key, waiting until the assigner wrote
@@ -203,12 +212,15 @@ type state struct {
 	nodes   map[string]bool
 	clone   time.Duration
 	slow    []string
+	// beside are the siblings read at their trunk's head, by repository (ADR 0548 §6).
+	beside map[string]string
 }
 
 // Judge runs the case (it is the Judge of a Checker). A failure of the change, of a merge or of a step is a verdict; an error is only a case that cannot
 // be judged at all.
 func (j *Examiner) Judge(ctx context.Context, c *Case) (Outcome, error) {
-	st := &state{j: j, c: c, levels: map[string]*acc{delivery.LevelUnit: {}, delivery.LevelIntegration: {}}, nodes: map[string]bool{}}
+	st := &state{j: j, c: c, levels: map[string]*acc{delivery.LevelUnit: {}, delivery.LevelIntegration: {}}, nodes: map[string]bool{},
+		beside: map[string]string{}}
 	if v := st.judgeAll(ctx); v != nil {
 		return st.finish(ctx, *v), nil
 	}
@@ -230,6 +242,13 @@ func (st *state) finish(ctx context.Context, v delivery.Verdict) Outcome {
 // fails the check, naming the machine it failed at. A try is not composed (it has no candidate); a composition that
 // cannot be had leaves it not run, said; with no assigner running it is not judged, said at once.
 func (st *state) composed(ctx context.Context, v *delivery.Verdict) {
+	if st.c.Composition != nil && st.c.Try == nil {
+		// A carry whose candidate's fingerprints did not change keeps the composition it passed (ADR 0548 §5).
+		kept := *st.c.Composition
+		v.Composition = &kept
+		st.c.note("the composition is kept: no fingerprint of a module it composed changed")
+		return
+	}
 	if st.j.Compositions == nil || st.c.Try != nil {
 		return
 	}
@@ -243,6 +262,9 @@ func (st *state) composed(ctx context.Context, v *delivery.Verdict) {
 		return
 	}
 	withComposition(v, comp)
+	if v.Composition != nil && v.Composition.State != delivery.CompositionNotRun {
+		v.Composition.FPSet = st.c.FPSet // a carry keeps it while the fingerprints stay the same (ADR 0548 §5)
+	}
 }
 
 // outcome fills the verdict's levels, times, machines and composition from what ran.
@@ -282,6 +304,9 @@ func (st *state) outcome(v delivery.Verdict) Outcome {
 		}
 	}
 	out := Outcome{Verdict: v, Slowest: slow}
+	if len(st.beside) > 0 {
+		out.Beside = st.beside
+	}
 	for _, t := range st.targets {
 		if t.judged != "" {
 			if out.Judged == nil {
@@ -343,6 +368,7 @@ func (st *state) judgeAll(ctx context.Context) *delivery.Verdict {
 				if len(beside) > 0 {
 					args["beside"] = beside
 					t.beside = besideLines(beside)
+					besideAtTrunk(st.c, beside, st.beside)
 				}
 				if p.Repository == catalogueRepository {
 					t.runner = RunnerWorkspace // used by the build module when the merge changes it (ADR 0535 §1)
@@ -364,11 +390,35 @@ func (st *state) judgeAll(ctx context.Context) *delivery.Verdict {
 	return nil
 }
 
+// DefaultDeclineBound is an Examiner's DeclineBound when it names none: longer than a check runs, so a node with the
+// need that is busy is waited for, and short enough that a mesh where no node has it says so.
+const DefaultDeclineBound = 30 * time.Minute
+
 // ask puts the target's check ask, waits for the step of the node that pulled it and judges its answer: the fetch, the
-// pins of its go.mod files, then each level's digest, kept verdicts and tests.
+// pins of its go.mod files, then each level's digest, kept verdicts and tests. When the answer leaves packages unmet,
+// their tests needing what that node lacks (issue 890), the passes are kept and the levels from the first such one are
+// asked again of a node that has it (placed).
 func (st *state) ask(ctx context.Context, t *target, merged *[]Fetched) *delivery.Verdict {
+	return st.askNeeding(ctx, t, merged, st.levelsOf(), nil, nil)
+}
+
+// askNeeding is ask with the levels to run, what the node must have and the packages it tests: none for the first ask
+// of a target; for the placed one the unmet packages' needs and those packages alone, so no package the first ask judged
+// is run or counted again (ADR 0552 §4).
+func (st *state) askNeeding(ctx context.Context, t *target, merged *[]Fetched, levels, needs, packages []string) *delivery.Verdict {
 	p := t.pull
-	job := &delivery.CheckJob{Fetch: t.fetchArgs, Levels: st.levelsOf(), Kept: true}
+	placed := len(needs) > 0
+	job := &delivery.CheckJob{Fetch: t.fetchArgs, Levels: levels, Kept: true, Packages: packages}
+	if st.j.Nodes != nil {
+		names, err := st.j.Nodes.Names(ctx)
+		if err == nil && len(names) == 0 {
+			err = fmt.Errorf("no node record is on the bus")
+		}
+		if err != nil {
+			return fail(t.module, fmt.Sprintf("the check of %s#%d is not asked: the nodes' names the names check needs cannot be read: %v", p.Repository, p.Number, err))
+		}
+		job.NodeNames = names
+	}
 	if t.runner != "" {
 		job.Runner, job.RunnerWhen = t.runner, buildGoDir
 	}
@@ -380,17 +430,53 @@ func (st *state) ask(ctx context.Context, t *target, merged *[]Fetched) *deliver
 		kind = delivery.AskRecheck // a re-judge after a trunk move goes after every new head's check (ADR 0536 §4)
 	}
 	a := delivery.StepAsk{ID: buildstep.NewID(), Kind: kind, Language: askLanguage[t.module], Asker: delivery.CheckerModule,
-		At: st.j.now().UTC(), Check: job}
-	st.c.Progress.Set(fmt.Sprintf("the %s ask %s of %s#%d", kind, a.ID, p.Repository, p.Number), "")
-	if err := st.j.Asks.Put(ctx, a); err != nil {
-		return fail(t.module, fmt.Sprintf("the check of %s#%d could not be asked: %v", p.Repository, p.Number, err))
-	}
-	step, err := st.j.Asks.Wait(ctx, a)
-	if err != nil {
-		if ctx.Err() != nil {
-			return fail(t.module, ctx.Err().Error())
+		At: st.j.now().UTC(), Check: job, Needs: needs}
+	var step delivery.Step
+	var firstDecline time.Time
+	for {
+		what := fmt.Sprintf("the %s ask %s of %s#%d", kind, a.ID, p.Repository, p.Number)
+		if placed {
+			what += " for a node with " + strings.Join(needs, ", ")
 		}
-		return fail(t.module, fmt.Sprintf("the check of %s#%d: %v", p.Repository, p.Number, err))
+		st.c.Progress.Set(what, "")
+		st.c.Asked(a.ID)
+		if err := st.j.Asks.Put(ctx, a); err != nil {
+			return fail(t.module, fmt.Sprintf("the check of %s#%d could not be asked: %v", p.Repository, p.Number, err))
+		}
+		waiting := ctx
+		if watch := st.c.Watch; watch != nil {
+			id := a.ID
+			watch(id, nil) // put: a try names it at once, not only when it ends (issue 1890)
+			waiting = buildrun.WithStepSeen(ctx, func(s delivery.Step) { watch(id, &s) })
+		}
+		var err error
+		step, err = st.j.Asks.Wait(waiting, a)
+		if err != nil {
+			if ctx.Err() != nil {
+				return fail(t.module, ctx.Err().Error())
+			}
+			return fail(t.module, fmt.Sprintf("the check of %s#%d: %v", p.Repository, p.Number, err))
+		}
+		d, declined := delivery.DeclinedOf(step)
+		if !declined {
+			break
+		}
+		// A node that lacks the need dropped the ask (issue 890): it is put again, for a node that has it to take; the
+		// node that declined looks at the stream again only after its next pull's wait.
+		now := st.j.now()
+		if firstDecline.IsZero() {
+			firstDecline = now
+		}
+		bound := st.j.DeclineBound
+		if bound <= 0 {
+			bound = DefaultDeclineBound
+		}
+		if now.Sub(firstDecline) > bound {
+			return fail(step.Node, fmt.Sprintf("the check of %s#%d needs a node with %s, and none took it in %s: every node that pulled it lacks it (last %s)",
+				p.Repository, p.Number, strings.Join(needs, ", "), bound, step.Node))
+		}
+		st.j.logf("%s#%d: the ask %s was declined on %s, which lacks %s; asked again", p.Repository, p.Number, a.ID, step.Node, strings.Join(d.Lacks, ", "))
+		a.ID, a.At = buildstep.NewID(), now.UTC()
 	}
 	// The fetch and the digests are what of the ask's time its levels' running did not take (Took.Clone).
 	took := time.Duration(0)
@@ -414,18 +500,31 @@ func (st *state) ask(ctx context.Context, t *target, merged *[]Fetched) *deliver
 		if st.c.Try == nil {
 			st.j.writePreview(ctx, p, append(*merged, t.fetched))
 		}
-		return fail(step.Node, fmt.Sprintf("%s#%d does not merge into the trunk: files in conflict: %s", p.Repository, p.Number, strings.Join(t.fetched.Conflicts, ", ")))
+		return fail(step.Node, fmt.Sprintf("%s#%d %s%s", p.Repository, p.Number, ConflictWords, strings.Join(t.fetched.Conflicts, ", ")))
 	}
 	t.changed = t.fetched.Changed
 	if !changesBuildGo(p.Repository, t.changed) {
 		t.runner = "" // the build module used no runner: the merge does not change it
 	}
-	*merged = append(*merged, t.fetched)
-	if v := st.checkPinsOf(ctx, t); v != nil {
-		return v
+	if !placed { // the placed ask fetched the same merge: its preview and pins were read from the first
+		*merged = append(*merged, t.fetched)
+		if v := st.checkPinsOf(ctx, t); v != nil {
+			return v
+		}
+		if v := st.checkBinariesOf(t); v != nil {
+			return v
+		}
 	}
 	ran := 0.0
 	for _, la := range answer.Levels {
+		if placed {
+			if len(la.Unmet) > 0 {
+				st.clone += max(0, took-time.Duration(ran*float64(time.Second)))
+				return fail(step.Node, fmt.Sprintf("the %s level of %s#%d left %s untested on %s, which was asked for a node with %s",
+					la.Level, p.Repository, p.Number, unmetNames(la.Unmet), step.Node, strings.Join(needs, ", ")))
+			}
+			la.Kept = nil // it names its packages and takes no other's kept verdict; this is only a guard against an older module
+		}
 		v, elapsed := st.level(ctx, t, la)
 		ran += elapsed
 		if v != nil {
@@ -434,12 +533,52 @@ func (st *state) ask(ctx context.Context, t *target, merged *[]Fetched) *deliver
 		}
 	}
 	st.clone += max(0, took-time.Duration(ran*float64(time.Second)))
+	if unmet := delivery.UnmetNeeds(answer.Levels); len(unmet) > 0 && !placed {
+		// Every level passed, its passes kept, and some packages were left to a node with what their tests need: the levels
+		// from the first that left one are asked of such a node, which takes the kept passes and tests those (issue 890).
+		var again, packages []string
+		seen := map[string]bool{}
+		for _, la := range answer.Levels {
+			if len(again) > 0 || len(la.Unmet) > 0 {
+				again = append(again, la.Level)
+			}
+			for _, u := range la.Unmet {
+				if !seen[u.Package] {
+					seen[u.Package] = true
+					packages = append(packages, u.Package)
+				}
+			}
+		}
+		st.j.logf("%s#%d: %s on %s left untested; asked of a node with %s", p.Repository, p.Number, unmetOf(answer.Levels), step.Node, strings.Join(unmet, ", "))
+		return st.askNeeding(ctx, t, merged, again, unmet, packages)
+	}
 	return nil
 }
 
+// unmetNames names the unmet packages and their needs.
+func unmetNames(unmet []delivery.PackageNeeds) string {
+	var out []string
+	for _, u := range unmet {
+		out = append(out, u.Package+" (needs "+strings.Join(u.Needs, ", ")+")")
+	}
+	return strings.Join(out, ", ")
+}
+
+// unmetOf names the unmet packages of every level.
+func unmetOf(levels []delivery.LevelAnswer) string {
+	var out []string
+	for _, la := range levels {
+		if len(la.Unmet) > 0 {
+			out = append(out, "at "+la.Level+" "+unmetNames(la.Unmet))
+		}
+	}
+	return strings.Join(out, "; ")
+}
+
 // level judges one level of a check ask's answer as the tools' answers were judged: the digest keys the kept verdicts
-// of the packages that passed, the kept ones taken are counted, and the first test result that did not pass is the
-// verdict. It answers the level's running time (its tests' and setup's).
+// of the packages that passed, the kept ones taken are counted, and every test result is read and counted, also after
+// one that did not pass, so the verdict names every failed test of the level (issue 1921). It answers the level's
+// running time (its tests' and setup's).
 func (st *state) level(ctx context.Context, t *target, la delivery.LevelAnswer) (*delivery.Verdict, float64) {
 	level := la.Level
 	a := st.levels[level]
@@ -461,6 +600,7 @@ func (st *state) level(ctx context.Context, t *target, la delivery.LevelAnswer)
 		a.kept += k.Tests
 	}
 	elapsed := 0.0
+	var failedResults []Tested
 	for _, raw := range la.Tests {
 		var res Tested
 		if err := json.Unmarshal(raw, &res); err != nil {
@@ -489,9 +629,12 @@ func (st *state) level(ctx context.Context, t *target, la delivery.LevelAnswer)
 			}
 		}
 		if !res.Passed {
-			return levelFailure(t, level, res), elapsed
+			failedResults = append(failedResults, res)
 		}
 	}
+	if len(failedResults) > 0 {
+		return levelFailure(t, level, failedResults...), elapsed
+	}
 	return nil, elapsed
 }
 
@@ -536,6 +679,12 @@ const MaxWords = 4096
 // no cause told apart (an older build module) the cause is the output's first "panic:", "fatal error:" or "signal:"
 // line, read before the output is cut, or the words say the tests passed and the program failed after them.
 func failureWords(f Failure) string {
+	return failureWordsAfter(f, "")
+}
+
+// failureWordsAfter is failureWords with the line loud put first, within the same MaxWords: what the checker itself says of
+// the failure (that the build module hid it), which the status line then names.
+func failureWordsAfter(f Failure, loud string) string {
 	out, passed := dropSummary(strings.TrimSpace(f.Output))
 	cause := strings.TrimSpace(f.Cause)
 	if cause == "" {
@@ -551,11 +700,14 @@ func failureWords(f Failure) string {
 	if len(cause) > MaxCause {
 		cause = strings.ToValidUTF8(cause[:MaxCause], "") + "..."
 	}
-	// The words keep MaxWords exactly: the cause and its newline, the marker and the kept lines (review round 1).
+	// The words keep MaxWords exactly: the loud line, the cause and their newlines, the marker and the kept lines.
 	budget := MaxWords
 	if cause != "" {
 		budget -= len(cause) + 1
 	}
+	if loud != "" {
+		budget -= len(loud) + 1
+	}
 	if len(out) > budget {
 		const marker = "... "
 		tail := out[len(out)-(budget-len(marker)):]
@@ -568,9 +720,31 @@ func failureWords(f Failure) string {
 	if cause != "" && !strings.HasPrefix(firstLine(out), cause) {
 		out = strings.TrimRight(cause+"\n"+out, "\n")
 	}
+	if loud != "" {
+		out = strings.TrimRight(loud+"\n"+out, "\n")
+	}
 	return out
 }
 
+// hidWords is the checker's loud line for a failure the build module sent hiding its cause (issue 1901, its thorough
+// fix): with no cause, or a passing line as its cause, under the failure contract (buildstep.Hidden). It names the build
+// module and the version it says it is (Tested.By, "<module> with mesh-sdk <version>"); one from before the contract
+// says nothing of itself. "" when the failure keeps the contract. The check fails either way: only its words change.
+func hidWords(module, by string, f Failure) string {
+	why := buildstep.Hidden(f)
+	if why == "" {
+		return ""
+	}
+	version := "a version before the failure contract"
+	if module == "" {
+		module = "an unnamed build module"
+	}
+	if m, v, ok := strings.Cut(by, " with "); ok && m != "" {
+		module, version = m, v
+	}
+	return fmt.Sprintf("the build module hid the failure (%s at %s): %s", module, version, why)
+}
+
 // MaxCause is the most a cause in a failure's words holds: one long line (the 1901 review: a cause of a kilobyte could
 // push the words past MaxWords).
 const MaxCause = 1024
@@ -633,23 +807,60 @@ func firstLine(s string) string {
 	return ""
 }
 
-// failure turns a level that did not pass into a verdict naming what failed first.
-func levelFailure(t *target, level string, res Tested) *delivery.Verdict {
+// MaxFailureLine is the most bytes of a failure's line in a verdict's Failures: the first line of its words, which is
+// its cause where the build module told one apart (issue 1901). Failed keeps the first failure's words whole.
+const MaxFailureLine = 300
+
+// levelFailure turns a level that did not pass into a verdict: Failed names what failed first with its words whole,
+// and Failures every failed test of the level's results with its first line, at most delivery.MaxFailures and an entry
+// saying how many more (issue 1921).
+func levelFailure(t *target, level string, results ...Tested) *delivery.Verdict {
 	v := delivery.Verdict{State: delivery.VerdictFail}
-	switch {
-	case len(res.Failed) > 0:
-		f := res.Failed[0]
-		name := failedName(f)
-		if t.module == buildrun.NodeBuildModule && f.Package == "" {
-			name = res.Module
+	var all []delivery.FailedFirst
+	for _, res := range results {
+		if len(res.Failed) == 0 {
+			why := res.Why
+			if why == "" {
+				why = "the " + level + " level did not pass"
+			}
+			all = append(all, delivery.FailedFirst{Test: level + ": " + t.pull.Repository, Words: why})
+			continue
 		}
-		v.Failed = delivery.FailedFirst{Test: level + ": " + name, Words: failureWords(f)}
-	default:
-		why := res.Why
-		if why == "" {
-			why = "the " + level + " level did not pass"
+		for _, f := range res.Failed {
+			name := failedName(f)
+			if t.module == buildrun.NodeBuildModule && f.Package == "" {
+				name = res.Module
+			}
+			all = append(all, delivery.FailedFirst{Test: level + ": " + name, Words: failureWordsAfter(f, hidWords(t.module, res.By, f))})
 		}
-		v.Failed = delivery.FailedFirst{Test: level + ": " + t.pull.Repository, Words: why}
 	}
+	if len(all) == 0 { // no result: a level said failed with nothing to name
+		all = append(all, delivery.FailedFirst{Test: level + ": " + t.pull.Repository, Words: "the " + level + " level did not pass"})
+	}
+	v.Failed = all[0]
+	v.Failures = failureLines(all)
 	return &v
 }
+
+// failureLines is every failure with the first line of its words, cut to MaxFailureLine, at most delivery.MaxFailures
+// and then one entry saying how many more failed.
+func failureLines(all []delivery.FailedFirst) []delivery.FailedFirst {
+	n := min(len(all), delivery.MaxFailures)
+	out := make([]delivery.FailedFirst, 0, n+1)
+	for _, f := range all[:n] {
+		out = append(out, delivery.FailedFirst{Test: f.Test, Machine: f.Machine, Words: clipLine(firstLine(f.Words), MaxFailureLine)})
+	}
+	if more := len(all) - n; more > 0 {
+		out = append(out, delivery.FailedFirst{Test: fmt.Sprintf("and %d more", more)})
+	}
+	return out
+}
+
+// clipLine cuts a line to at most n bytes on a whole character, marking the cut.
+func clipLine(s string, n int) string {
+	if len(s) <= n {
+		return s
+	}
+	s = strings.ToValidUTF8(s[:n-3], "")
+	return s + "..."
+}

modules/mesh-delivery-checker/internal/check/kept.go

@@ -56,12 +56,22 @@ func (k Kept) Keep(ctx context.Context, level, digest string, v delivery.Kept) (
 
 // KeepPasses keeps, for the packages of a test result that passed with tests, a verdict under the digest the build module
 // named for the package at the level. A package that failed, has no tests or has no digest is never kept (ADR 0444 clause
-// 1): it runs every check. It answers the packages it kept now.
+// 1): it runs every check. A package with skipped tests is not kept either: a pass that skipped (a test needing a
+// toolchain the node lacks) would be reused for its digest and never run anywhere (issue 890). A build module that
+// counts skips only per result, not per package, keeps nothing of a result in which a test skipped. It answers the
+// packages it kept now.
 func (k Kept) KeepPasses(ctx context.Context, repository, level, toolchain string, res Tested, digests map[string]string, at time.Time) ([]string, error) {
 	var kept []string
+	perPackage := false
+	for _, p := range res.Packages {
+		perPackage = perPackage || p.Skipped > 0
+	}
+	if res.Skipped > 0 && !perPackage {
+		return kept, nil // an older build module: the skip cannot be placed in a package
+	}
 	for _, p := range res.Packages {
 		digest, ok := digests[p.Package]
-		if !ok || !p.Passed || p.NoTests || p.Tests == 0 {
+		if !ok || !p.Passed || p.NoTests || p.Tests == 0 || p.Skipped > 0 {
 			continue
 		}
 		if failedIn(res, p.Package) {

modules/mesh-delivery-checker/internal/check/kept_test.go

@@ -74,6 +74,32 @@ func TestOnlyPassingPackagesWithADigestAreKept(t *testing.T) { // 1287/AC3, AC4
 	}
 }
 
+func TestAResultWithSkippedTestsKeepsNothing(t *testing.T) { // issue 890: a pass that skipped proved nothing
+	ctx, st := context.Background(), newMemKV()
+	k := Kept{Store: st}
+	res := Tested{Level: "integration", Passed: true, Skipped: 2, Packages: []GoPackage{{Package: "m/a", Passed: true, Tests: 4}}}
+	kept, err := k.KeepPasses(ctx, "novox/mesh-catalog", "integration", "go1.26.0", res, map[string]string{"m/a": digA}, at0)
+	if err != nil || len(kept) != 0 {
+		t.Fatalf("kept %v, %v, want nothing", kept, err)
+	}
+	if keys, _ := st.Keys(ctx); len(keys) != 0 {
+		t.Errorf("the bucket holds %v, want none", keys)
+	}
+}
+
+func TestOnlyTheSkippingPackageOfAResultIsWithheld(t *testing.T) { // issue 890
+	ctx, st := context.Background(), newMemKV()
+	k := Kept{Store: st}
+	res := Tested{Level: "integration", Passed: true, Skipped: 2, Packages: []GoPackage{
+		{Package: "m/a", Passed: true, Tests: 4, Skipped: 2},
+		{Package: "m/b", Passed: true, Tests: 3},
+	}}
+	kept, err := k.KeepPasses(ctx, "novox/mesh-catalog", "integration", "go1.26.0", res, map[string]string{"m/a": digA, "m/b": digB}, at0)
+	if err != nil || strings.Join(kept, ",") != "m/b" {
+		t.Fatalf("kept %v, %v, want only m/b", kept, err)
+	}
+}
+
 func TestAKeptValueOfAnotherDigestIsNotRead(t *testing.T) { // 1287/AC7
 	ctx, st := context.Background(), newMemKV()
 	k := Kept{Store: st}

modules/mesh-delivery-checker/internal/check/line.go

@@ -49,6 +49,34 @@ func firstFailed(v delivery.Verdict) string {
 	return firstWordsLine(f.Words)
 }
 
+// failedLines is everything a verdict names as failed, one line each: every failed test with its first line (issue
+// 1921), or what failed first when the verdict names no list (a conflict, a refused step, an older verdict).
+func failedLines(v delivery.Verdict) []string {
+	if len(v.Failures) == 0 {
+		if f := firstFailed(v); f != "" {
+			return []string{f}
+		}
+		return nil
+	}
+	lines := make([]string, 0, len(v.Failures))
+	for _, f := range v.Failures {
+		lines = append(lines, firstFailed(delivery.Verdict{Failed: f}))
+	}
+	return lines
+}
+
+// failedCount is how many tests a verdict names as failed, the ones after delivery.MaxFailures counted too.
+func failedCount(v delivery.Verdict) int {
+	n := len(v.Failures)
+	if n > delivery.MaxFailures {
+		var more int
+		if _, err := fmt.Sscanf(v.Failures[n-1].Test, "and %d more", &more); err == nil {
+			return delivery.MaxFailures + more
+		}
+	}
+	return n
+}
+
 // firstWordsLine is the first line of a failure's words: the words are several lines (issue 1901) and the status line one.
 func firstWordsLine(w string) string { return firstLine(w) }
 
@@ -57,18 +85,22 @@ type pieces struct {
 	head, commits, counts, shortCounts, times, shortTimes, over, builds, composition, shortComposition, group string
 	// judged names the program that judged a change to a build module (ADR 0535 §5); never dropped.
 	judged string
+	// carried says, of a carried verdict, the commits it was carried from (ADR 0548 §8); never dropped.
+	carried string
+	// warning says that a part of the check did not run, for instance that an older build module could not refuse a compiled program; never dropped.
+	warning string
 }
 
 // pullKey names a pull request of a case: `<owner/repo>#<number>`.
 func pullKey(p Pull) string { return fmt.Sprintf("%s#%d", p.Repository, p.Number) }
 
 func (p pieces) join(drop int) string {
-	parts := []string{p.head, p.commits, p.counts, p.judged}
+	parts := []string{p.head, p.commits, p.carried, p.warning, p.counts, p.judged}
 	switch {
 	case drop < 3 && p.times != "":
 		parts = append(parts, p.times)
 	case drop == 3 && p.shortTimes != "":
-		parts = []string{p.head, p.commits, p.shortCounts, p.judged, p.shortTimes}
+		parts = []string{p.head, p.commits, p.carried, p.warning, p.shortCounts, p.judged, p.shortTimes}
 	}
 	if p.over != "" {
 		parts = append(parts, p.over)
@@ -143,18 +175,67 @@ func buildWords(builds []BuildNote) string {
 	return "builds: " + strings.Join(parts, ", ")
 }
 
+// carriedWords say the commits a verdict was carried from, for the line of pull request p (ADR 0548 §8): its own trunk's
+// commit as twelve characters, a sibling's with its name before it; only those that moved, sorted. Empty when none did.
+func carriedWords(from map[string]string, v delivery.Verdict, cs *Case, p Pull) string {
+	var own string
+	var others []string
+	for r, old := range from {
+		now, ok := v.Trunk[r]
+		if cs != nil && !ok {
+			now, ok = cs.Trunk[r]
+		}
+		if !ok {
+			now = v.Beside[r]
+		}
+		if now == "" || now == old {
+			continue
+		}
+		if strings.EqualFold(r, p.Repository) {
+			own = short12(old)
+			continue
+		}
+		name := r
+		if i := strings.LastIndex(r, "/"); i >= 0 {
+			name = r[i+1:]
+		}
+		others = append(others, name+" "+short12(old))
+	}
+	slices.Sort(others)
+	if own != "" {
+		others = append([]string{own}, others...)
+	}
+	return strings.Join(others, ", ")
+}
+
 // parts makes the pieces of the line of a pull request of a case.
 func parts(v delivery.Verdict, cs *Case, p Pull, builds []BuildNote, slowest []string, judged map[string]string) pieces {
 	var pc pieces
 	pc.judged = judged[pullKey(p)]
+	if cs != nil {
+		pc.warning = cs.Warning(pullKey(p))
+	}
 	commits := short12(p.Head) + " on " + short12(p.Trunk)
 	switch v.State {
 	case delivery.VerdictRunning:
 		pc.head = "checking " + commits
+		if cs != nil && cs.CarriedFrom != nil {
+			// Out of date and being carried to the new commit (ADR 0548 §6): pending, and saying so.
+			pc.head = "being carried to " + commits
+			if w := carriedWords(cs.CarriedFrom, v, cs, p); w != "" {
+				pc.carried = "from " + w
+			}
+		}
 	case delivery.VerdictPass:
 		pc.head = "pass " + commits
+		if w := carriedWords(v.CarriedFrom, v, cs, p); w != "" {
+			pc.carried = "carried from " + w // the counts that follow say what the carry ran and kept
+		}
 	default:
 		pc.head = "failed: " + firstFailed(v)
+		if n := failedCount(v); n > 1 {
+			pc.head = fmt.Sprintf("failed (%d tests): %s", n, firstFailed(v))
+		}
 		pc.commits = commits
 	}
 	var counts []string

modules/mesh-delivery-checker/internal/check/lostask.go

@@ -0,0 +1,39 @@
+package check
+
+import (
+	"strings"
+
+	"git.novox.be/novox/mesh-sdk/go/buildstep"
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+	"git.novox.be/novox/mesh-sdk/go/delivery/buildrun"
+)
+
+// **An ask the build seat gave up on ends its step** (novox/hq issue 734): mesh-sdk buildrun.LostAskWaiter hands the
+// waiting asker a failed step on the node buildrun.LostNode when DEAD_LETTERS keeps the ask's copy (buildrun.HearDeadLetters,
+// granted by buscompose DeadLetterReads), and, under buildrun.NotTakenBound, when no build node took the ask within the
+// bound. What follows is the checker's: a try ends as error (Tryer.run), with the not-taken bound at the step bound
+// (Tryer.NotTaken); a check is asked again under its claim, at most LostAskTries times, then fails as not heard and is
+// judged again when the nodes change (Checker.try). A check's ask has no not-taken bound: it waits in the stream as long as
+// the backlog is (ADR 0525 §9), and a check ended for a backlog would owe its pull request a failure.
+
+// LostAskTries is how often a check asks again whose ask was given up, before it fails as not heard (UnheardWords) and is
+// judged again when the nodes change.
+const LostAskTries = 3
+
+// IsLostAsk says whether a verdict failed because its ask judged nothing: the build seat gave it up (buildrun.LostWords), or
+// the build module that ran its step was replaced under it, and its next process ended the step it left running
+// (buildstep.RestartReason; a delivery of the build module, as on 2026-10-28). Neither is the change's failure: the check
+// is asked again, as for a given-up ask.
+func IsLostAsk(v delivery.Verdict) bool {
+	return v.State == delivery.VerdictFail && (strings.Contains(v.Failed.Words, buildrun.LostWords) ||
+		strings.Contains(v.Failed.Words, buildstep.RestartReason))
+}
+
+// IsNotTaken says whether a verdict failed because no build node took its ask within the bound (buildrun.NotTakenWords).
+func IsNotTaken(v delivery.Verdict) bool {
+	return v.State == delivery.VerdictFail && strings.Contains(v.Failed.Words, buildrun.NotTakenWords)
+}
+
+// HearingBucket is the checker's state hearing: whether it hears DEAD_LETTERS (buildrun.Hearing under
+// buildrun.HearingKey), which checker_status says (dead_letters).
+const HearingBucket = delivery.CheckerModule + "_" + buildrun.HearingState

modules/mesh-delivery-checker/internal/check/lostask_test.go

@@ -0,0 +1,347 @@
+package check
+
+import (
+	"context"
+	"encoding/json"
+	"strings"
+	"sync"
+	"testing"
+	"time"
+
+	"git.novox.be/novox/mesh-sdk/go/buildstep"
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+	"git.novox.be/novox/mesh-sdk/go/delivery/buildrun"
+)
+
+// losingAsks is the build seat over a bus that gives up the first `lose` asks put (DEAD_LETTERS keeps them, as on
+// 2026-10-26 during a bus reload: try-1793017340003993788) and answers the rest; with never set it neither answers nor
+// gives up (an ask no node takes).
+type losingAsks struct {
+	*buildrun.FakeAsks
+	answer func(delivery.StepAsk) delivery.Step
+	dead   *buildrun.DeadLetters
+	never  bool
+
+	mu   sync.Mutex
+	lose int
+}
+
+func (l *losingAsks) PublishAsk(ctx context.Context, subject, id string, data []byte) error {
+	if err := l.FakeAsks.PublishAsk(ctx, subject, id, data); err != nil {
+		return err
+	}
+	l.mu.Lock()
+	lost := l.lose > 0
+	if lost {
+		l.lose--
+	}
+	l.mu.Unlock()
+	switch {
+	case l.never:
+	case lost:
+		h := map[string][]string{buildrun.DeadHeaderMsgID: {id}, buildrun.DeadHeaderDeliveries: {"5"}, buildrun.DeadHeaderStream: {"SEAT_NODE_BUILD_GO"},
+			buildrun.DeadHeaderGaveUp: {"2026-10-26T12:26:40Z"}}
+		g, ok := buildrun.GivenUpOf(h)
+		if !ok {
+			return nil
+		}
+		go l.dead.Heard(g)
+	default:
+		a, err := delivery.DecodeStepAsk(data)
+		if err != nil {
+			return err
+		}
+		l.Write(l.answer(a))
+	}
+	return nil
+}
+
+func losing(b *bench, lose int) *losingAsks {
+	l := &losingAsks{FakeAsks: &buildrun.FakeAsks{}, answer: b.answer, dead: &buildrun.DeadLetters{}, lose: lose}
+	b.ex.Asks = buildrun.Asker{Publisher: l, Waiter: buildrun.LostAskWaiter{Inner: l.FakeAsks, Dead: l.dead}, Bound: 5 * time.Second}
+	return l
+}
+
+// endable is the tries state as the end tool sees it.
+type endable struct{ kv *memKV }
+
+func (e endable) Entry(key string) (json.RawMessage, uint64, error) {
+	v, rev, _, err := e.kv.Get(context.Background(), key)
+	return v, rev, err
+}
+func (e endable) Update(key string, value []byte, revision uint64) error {
+	_, err := e.kv.Update(context.Background(), key, value, revision)
+	return err
+}
+
+// Issue 734: a try whose ask the build seat gave up on ends as error saying so, and the next ask of its head is a new try;
+// one no node takes ends at the step bound; one ended by hand frees its place and stops being waited for.
+func TestAnAskGivenUpOrNeverTakenEndsItsTryAsErrorAndItsHeadIsAskedAnew(t *testing.T) {
+	ctx := context.Background()
+	for _, row := range []struct {
+		name  string
+		lose  int
+		never bool
+		want  string
+	}{
+		{"given up by the build seat", 1, false, buildrun.LostWords + " after 5 deliveries at 2026-10-26T12:26:40Z"},
+		{"taken by no build node within the bound", 0, true, buildrun.NotTakenWords + " within 200ms"},
+	} {
+		t.Run(row.name, func(t *testing.T) {
+			kv := newMemKV()
+			at := time.Date(2026, 10, 26, 12, 22, 20, 0, time.UTC)
+			id, err := AskTry(memTries{kv}, tryTrunks, TryAsk{Repository: repoA, Head: head1}, at)
+			if err != nil {
+				t.Fatal(err)
+			}
+			b := newBench(t)
+			l := losing(b, row.lose)
+			l.never = row.never
+			tr := &Tryer{Tries: kv, Judge: b.ex, NotTaken: 200 * time.Millisecond}
+			raw, _, _, _ := kv.Get(ctx, id)
+			tr.Put(ctx, id, raw)
+			tr.Wait()
+			got := readTry(t, kv, id)
+			if got.State != TryError || len(got.Failed) != 1 || !strings.Contains(got.Failed[0], row.want) || !strings.Contains(got.Said, row.want) {
+				t.Fatalf("try = %+v, want error saying %q", got, row.want)
+			}
+			again, err := AskTry(memTries{kv}, tryTrunks, TryAsk{Repository: repoA, Head: head1}, at.Add(time.Minute))
+			if err != nil || again == id {
+				t.Errorf("the head asked again answered %q, %v, want a new try", again, err)
+			}
+		})
+	}
+	t.Run("ended by hand", func(t *testing.T) {
+		kv := newMemKV()
+		id, _ := AskTry(memTries{kv}, tryTrunks, TryAsk{Repository: repoA, Head: head1}, time.Now())
+		b := newBench(t)
+		losing(b, 0).never = true
+		tr := &Tryer{Tries: kv, Judge: b.ex} // no bound: only the hand ends it
+		raw, _, _, _ := kv.Get(ctx, id)
+		tr.Put(ctx, id, raw)
+		deadline := time.Now().Add(2 * time.Second)
+		for readTry(t, kv, id).State != TryRunning && time.Now().Before(deadline) {
+			time.Sleep(5 * time.Millisecond)
+		}
+		if _, err := EndTry(endable{kv}, id, "", time.Now()); err == nil {
+			t.Error("an end without a why was taken")
+		}
+		ended, err := EndTry(endable{kv}, id, "its ask was lost in the bus reload", time.Now())
+		if err != nil || ended.State != TryError || !strings.HasPrefix(ended.Said, "ended by hand ("+TryEndTool+"): its ask was lost") {
+			t.Fatalf("ended = %+v, %v", ended, err)
+		}
+		raw, _, _, _ = kv.Get(ctx, id)
+		tr.Put(ctx, id, raw) // the watch of the tries hands the end over
+		tr.Wait()            // returns: the try's judging stopped
+		if got := readTry(t, kv, id); got.State != TryError || got.Said != ended.Said {
+			t.Errorf("try = %+v, want the hand's end kept", got)
+		}
+		if _, err := EndTry(endable{kv}, id, "again", time.Now()); err == nil || !strings.Contains(err.Error(), "ended already") {
+			t.Errorf("a second end answered %v", err)
+		}
+	})
+}
+
+// troubled is the build seat as a check meets it when its step's end does not reach its wait: the first `restarts` asks'
+// steps are ended by the build module's next process (buildstep.RestartReason), and the first `deaf` asks' watches hear
+// nothing though their steps end (the lost check of 2026-10-28). Its steps state is read through AskSteps and Steps.
+type troubled struct {
+	*buildrun.FakeAsks
+	answer func(delivery.StepAsk) delivery.Step
+
+	mu             sync.Mutex
+	restarts, deaf int
+	deafIDs        map[string]bool
+	steps          map[string]delivery.Step
+}
+
+func (tr *troubled) PublishAsk(ctx context.Context, subject, id string, data []byte) error {
+	if err := tr.FakeAsks.PublishAsk(ctx, subject, id, data); err != nil {
+		return err
+	}
+	a, err := delivery.DecodeStepAsk(data)
+	if err != nil {
+		return err
+	}
+	step := tr.answer(a)
+	step.What = buildstep.AskWhat(a)
+	tr.mu.Lock()
+	if tr.restarts > 0 {
+		tr.restarts--
+		step.State, step.Reason, step.Result = delivery.StepFailed, buildstep.RestartReason, nil
+	}
+	deaf := tr.deaf > 0
+	if deaf {
+		tr.deaf--
+		tr.deafIDs[id] = true
+	}
+	tr.steps[id] = step
+	tr.mu.Unlock()
+	if !deaf {
+		tr.Write(step)
+	}
+	return nil
+}
+
+func (tr *troubled) WatchAsk(ctx context.Context, module, askID string) (<-chan delivery.Step, error) {
+	tr.mu.Lock()
+	deaf := tr.deafIDs[askID]
+	tr.mu.Unlock()
+	if deaf {
+		return make(chan delivery.Step), nil // open, and silent for good
+	}
+	return tr.FakeAsks.WatchAsk(ctx, module, askID)
+}
+
+func (tr *troubled) AskSteps(_ context.Context, _, askID string) ([]delivery.Step, error) {
+	tr.mu.Lock()
+	defer tr.mu.Unlock()
+	if s, ok := tr.steps[askID]; ok {
+		return []delivery.Step{s}, nil
+	}
+	return nil, nil
+}
+
+// Steps is the steps state as the read tools read it, with running in place of every step the hand has not let end.
+func (tr *troubled) Steps(running bool) StateRead {
+	tr.mu.Lock()
+	defer tr.mu.Unlock()
+	vals := map[string]json.RawMessage{}
+	for id, s := range tr.steps {
+		if running {
+			s.State, s.Ended, s.Started = delivery.StepRunning, time.Time{}, time.Now()
+		}
+		raw, _ := delivery.EncodeStep(s)
+		vals[s.Node+"."+id] = raw
+	}
+	return StateRead{Keys: func() ([]string, error) {
+		var out []string
+		for k := range vals {
+			out = append(out, k)
+		}
+		return out, nil
+	}, Get: func(k string) (json.RawMessage, error) { return vals[k], nil }}
+}
+
+// kvRead is a bucket in memory as the read tools read it, live.
+func kvRead(kv *memKV) StateRead {
+	return StateRead{Keys: func() ([]string, error) { return kv.Keys(context.Background()) },
+		Get: func(k string) (json.RawMessage, error) {
+			v, _, _, err := kv.Get(context.Background(), k)
+			return v, err
+		}}
+}
+
+// asVerdicts is the rig's verdicts as the ask-again tool reads and writes them.
+type asVerdicts struct{ kv *memKV }
+
+func (a asVerdicts) Entry(key string) (json.RawMessage, uint64, error) {
+	v, rev, _, err := a.kv.Get(context.Background(), key)
+	return v, rev, err
+}
+func (a asVerdicts) Update(key string, value []byte, revision uint64) error {
+	_, err := a.kv.Update(context.Background(), key, value, revision)
+	return err
+}
+
+// Issue 734 and the lost check of 2026-10-28: a check whose ask judged nothing is asked again, and one whose step ended
+// unheard is judged. Given up by the build seat once, or its step ended by the build module's next process after a
+// delivery replaced it, the check is asked again under its claim and passes; given up every time it fails loudly as not
+// heard, judged again when the nodes change. A step whose watch went deaf is read at the next step end of its build module
+// (a nudge) and judged with no new ask; one no event reaches is named lost by checker_status, refused by checker_ask_again
+// while its step still runs, and asked again by it once its step ended.
+func TestACheckWhoseAskJudgedNothingIsAskedAgainOrRead(t *testing.T) {
+	ctx := context.Background()
+	for _, row := range []struct {
+		name                 string
+		lose, restarts, deaf int
+		how                  string // "nudge": a step of the build module ends; "hand": checker_ask_again
+		state                string
+		asks                 int
+	}{
+		{name: "given up once", lose: 1, state: delivery.VerdictPass, asks: 2},
+		{name: "given up every time", lose: LostAskTries, state: delivery.VerdictFail, asks: LostAskTries},
+		{name: "its build module replaced under it", restarts: 1, state: delivery.VerdictPass, asks: 2},
+		{name: "replaced under every ask", restarts: LostAskTries, state: delivery.VerdictFail, asks: LostAskTries},
+		{name: "its watch deaf, a step of its build module ends", deaf: 1, how: "nudge", state: delivery.VerdictPass, asks: 1},
+		{name: "its watch deaf, asked again by hand", deaf: 1, how: "hand", state: delivery.VerdictPass, asks: 2},
+		{name: "its watch deaf, asked again by hand after its build module replaced it", deaf: 1, restarts: 1, how: "hand", state: delivery.VerdictPass, asks: 2},
+	} {
+		t.Run(row.name, func(t *testing.T) {
+			b := newBench(t)
+			var asked func() int
+			var heard *buildrun.HeardEnds
+			var tr *troubled
+			if row.lose > 0 {
+				l := losing(b, row.lose)
+				asked = func() int { return len(l.Asks()) }
+			} else {
+				tr = &troubled{FakeAsks: &buildrun.FakeAsks{}, answer: b.answer, restarts: row.restarts, deaf: row.deaf,
+					deafIDs: map[string]bool{}, steps: map[string]delivery.Step{}}
+				heard = &buildrun.HeardEnds{Inner: tr, Read: tr}
+				b.ex.Asks = buildrun.Asker{Publisher: tr, Waiter: heard, Bound: 5 * time.Second}
+				asked = func() int { return len(tr.Asks()) }
+			}
+			r := newRig(t, b.ex)
+			asksKept := newMemKV()
+			r.ch.Asks = asksKept
+			cand := candidateOf(t, "feat/x", pullOf(repoA, 7, head1))
+			key := keyOf(t, "feat/x", cand)
+			r.ch.Candidate(ctx, "feat%2Fx", cand)
+			if row.deaf > 0 {
+				for deadline := time.Now().Add(2 * time.Second); heard.Waiting() == 0 && time.Now().Before(deadline); {
+					time.Sleep(2 * time.Millisecond)
+				}
+				if v := r.verdict(t, key); v.State != delivery.VerdictRunning {
+					t.Fatalf("a check whose step ended unheard = %s, want running until it is read", v.State)
+				}
+			}
+			switch row.how {
+			case "nudge":
+				heard.Nudge(buildrun.NodeBuildModule) // another build module's step: not this one's to read
+				heard.Nudge(buildrun.GoBuildModule)
+			case "hand":
+				cands := newMemKV()
+				ckey, _ := delivery.CandidatesKey("feat/x")
+				_, _ = cands.Create(ctx, ckey, cand)
+				none := StateRead{Keys: func() ([]string, error) { return nil, nil }, Get: func(string) (json.RawMessage, error) { return nil, nil }}
+				rd := Reader{CandidateState: kvRead(cands), VerdictState: kvRead(r.verdicts), AskState: kvRead(asksKept),
+					StepStates: map[string]StateRead{buildrun.GoBuildModule: none}} // no node took its ask yet
+				if _, err := rd.AskAgain(asVerdicts{r.verdicts}, "feat/x", "its watch went deaf"); err == nil || !strings.Contains(err.Error(), "waits in its build seat's stream") {
+					t.Errorf("asked again while its ask waits in the stream (issue 1791's kind): %v", err)
+				}
+				rd.StepStates[buildrun.GoBuildModule] = tr.Steps(true)
+				if _, err := rd.AskAgain(asVerdicts{r.verdicts}, "feat/x", "its watch went deaf"); err == nil || !strings.Contains(err.Error(), "a step of it runs") {
+					t.Errorf("asked again while its step runs: %v", err)
+				}
+				rd.StepStates[buildrun.GoBuildModule] = tr.Steps(false)
+				if st, _ := rd.Status(); !strings.Contains(st.Lost["feat/x"], AskAgainTool) {
+					t.Errorf("status lost = %v, want feat/x named with %s", st.Lost, AskAgainTool)
+				}
+				got, err := rd.AskAgain(asVerdicts{r.verdicts}, "feat/x", "its watch went deaf")
+				if err != nil || got.Key != key || !strings.HasPrefix(got.Said, AskedAgainWords) {
+					t.Fatalf("asked again = %+v, %v", got, err)
+				}
+				raw, _, _, _ := r.verdicts.Get(ctx, key)
+				r.ch.VerdictWritten(ctx, key, raw) // the checker's watch of its verdicts hands it over
+			}
+			r.ch.Wait()
+			v := r.verdict(t, key)
+			if v.State != row.state || asked() != row.asks {
+				t.Errorf("verdict %s (%s) after %d asks, want %s after %d", v.State, v.Failed.Words, asked(), row.state, row.asks)
+			}
+			if _, _, kept, _ := asksKept.Get(ctx, key); kept {
+				t.Errorf("the asks of the ended check are still kept under %s", key)
+			}
+			if row.state == delivery.VerdictFail && (!IsLostAsk(v) || !IsNodesFailure(v)) {
+				t.Errorf("a check that judged nothing every time = %q, want lost and judged again when the nodes change", v.Failed.Words)
+			}
+			if row.how == "hand" {
+				rd := Reader{VerdictState: kvRead(r.verdicts), CandidateState: kvRead(newMemKV())}
+				if _, err := rd.AskAgain(asVerdicts{r.verdicts}, "feat/x", "again"); err == nil {
+					t.Error("a judged check was asked again")
+				}
+			}
+		})
+	}
+}

modules/mesh-delivery-checker/internal/check/package_cause_test.go

@@ -38,11 +38,11 @@ func TestAPackageFailureIsNeverWordedPass(t *testing.T) { // 1901/AC5
 					t.Errorf("1901/AC5: the words keep %q: %q", l, v.Failed.Words)
 				}
 			}
-			if !strings.HasPrefix(v.Failed.Words, c.want) {
-				t.Errorf("1901/AC5: words start %q, want %q", firstLine(v.Failed.Words), c.want)
+			if !strings.HasPrefix(afterHid(v.Failed.Words), c.want) {
+				t.Errorf("1901/AC5: words after the loud line start %q, want %q", firstLine(afterHid(v.Failed.Words)), c.want)
 			}
-			if got := firstFailed(*v); !strings.Contains(got, c.want) || strings.HasSuffix(got, ": PASS") {
-				t.Errorf("1901/AC5: status = %q", got)
+			if got := firstFailed(*v); !strings.Contains(got, "the build module hid the failure") || strings.HasSuffix(got, ": PASS") {
+				t.Errorf("1901/AC5, AC8: status = %q", got)
 			}
 		})
 	}
@@ -63,7 +63,7 @@ func TestALongCauseIsCutToALinesBound(t *testing.T) { // 1901/AC5
 func TestAPackageStoppedWithOnlyItsFailLineIsStillWorded(t *testing.T) { // 1901/AC5
 	for _, out := range []string{"FAIL\texample.com/timeout\t2.017s", "FAIL\texample.com/exiting\t0.006s", "FAIL\texample.com/killed\t0.006s"} {
 		v := levelFailure(&target{}, "integration", Tested{Failed: []Failure{{Package: "example.com/x", Output: out}}})
-		if !strings.HasPrefix(v.Failed.Words, "the package failed with no test to name and no panic, signal or build error in its output") {
+		if !strings.HasPrefix(afterHid(v.Failed.Words), "the package failed with no test to name and no panic, signal or build error in its output") {
 			t.Errorf("1901/AC5: %q is worded %q", out, v.Failed.Words)
 		}
 	}
@@ -74,7 +74,7 @@ func TestAPackageStoppedWithOnlyItsFailLineIsStillWorded(t *testing.T) { // 1901
 func TestOnlyGosExactFormsAreSummaryOrCause(t *testing.T) { // 1901/AC5
 	out := "    x_test.go:3: ok so far\nok then: the seat is free\n        panic: child retried and recovered\npanic: the real one\nFAIL\tp\t1.0s"
 	v := levelFailure(&target{}, "unit", Tested{Failed: []Failure{{Package: "p", Output: out}}})
-	if !strings.HasPrefix(v.Failed.Words, "panic: the real one") || !strings.Contains(v.Failed.Words, "ok then: the seat is free") {
+	if !strings.HasPrefix(afterHid(v.Failed.Words), "panic: the real one") || !strings.Contains(v.Failed.Words, "ok then: the seat is free") {
 		t.Errorf("1901/AC5: words = %q", v.Failed.Words)
 	}
 }
@@ -90,3 +90,13 @@ func TestTheWordsKeepTheirBoundExactly(t *testing.T) { // 1901/AC5
 		}
 	}
 }
+
+// afterHid is a verdict's words after the checker's loud line, which a failure with no cause from an older build module
+// now starts with (1901/AC8).
+func afterHid(w string) string {
+	if strings.HasPrefix(w, "the build module hid the failure") {
+		_, rest, _ := strings.Cut(w, "\n")
+		return rest
+	}
+	return w
+}

modules/mesh-delivery-checker/internal/check/pins_test.go

@@ -240,7 +240,12 @@ func TestTheSiblingsAreWhereTheTestsStateThem(t *testing.T) { // review D2, ADR
 		catalogue + " go.mod " + head2: "module git.novox.be/novox/mesh-catalog\n"}, onTrunk: map[string]bool{"cb54756c3865": true}}
 	b.ex.Forge = forge
 	// A group of the controller and the catalogue: the controller's tests read the catalogue's trunk, not the group's head.
-	b.judge(t, caseOf(t, pullOf(controller, 7, head1), pullOf(catalogue, 12, head2)))
+	out := b.judge(t, caseOf(t, pullOf(controller, 7, head1), pullOf(catalogue, 12, head2)))
+	// ADR 0548 §6, issue 568's own example: the verdict names the node-engine at the commit the mesh runs, and mesh-sdk at the
+	// trunk the catalogue's tests read it at; the catalogue, a member here, is not named.
+	if out.Beside[host] != hostRuns || out.Beside[catalogue] != "" || out.Beside[SDKRepository] != "9999999999999999999999999999999999999999" {
+		t.Errorf("the siblings named for the verdict = %v, want the node-engine at %s and mesh-sdk at its trunk", out.Beside, hostRuns[:12])
+	}
 	got := besideOf(t, b, controller)
 	if c := got[catalogue]; c.Commit != trunkS || c.Ref != "" {
 		t.Errorf("the catalogue beside the controller = %+v, want its trunk %s", c, trunkS)
@@ -324,7 +329,11 @@ func TestTheChangesOwnRepositoryIsBesideItAtItsTrunk(t *testing.T) {
 func TestACatalogueChangeHasTheCatalogueBesideItAtItsTrunk(t *testing.T) {
 	b := newBench(t)
 	b.ex.Trunks = trunksOf(t, map[string]string{catalogueRepository: trunkA, SDKRepository: trunkS, controllerRepo: trunkA2})
-	b.judge(t, caseOf(t, pullOf(catalogueRepository, 12, head1)))
+	out := b.judge(t, caseOf(t, pullOf(catalogueRepository, 12, head1)))
+	// ADR 0548 §6: the outcome names the siblings read at their trunk's head, never the repository it merges.
+	if out.Beside[SDKRepository] != trunkS || out.Beside[controllerRepo] != trunkA2 || out.Beside[catalogueRepository] != "" {
+		t.Errorf("the siblings named for the verdict = %v, want mesh-sdk and mesh-controller at their trunks and not the catalogue", out.Beside)
+	}
 	got := besideOf(t, b, catalogueRepository)
 	if c := got[catalogueRepository]; c.Commit != trunkA || c.Ref != "" {
 		t.Fatalf("the catalogue beside its own change = %+v, want its trunk %s", c, trunkA)

modules/mesh-delivery-checker/internal/check/rank_test.go

@@ -75,3 +75,40 @@ func TestCheckerStatusNamesTheWaitingChecksByKind(t *testing.T) { // 1897/AC4
 		t.Errorf("waiting = %v, want %v", st.Waiting, want)
 	}
 }
+
+// 568 note 21: a verdict that read the node-engine at its running commit is not waiting for a trunk move while that commit
+// is still the one the mesh runs, though the node-engine's trunk has moved on (ADR 0548 §6).
+func TestCheckerStatusReadsTheNodeEngineAtItsRunningCommit(t *testing.T) { // 568/21
+	cand := candidateOf(t, group(1), pullOf(repoA, 1, head1))
+	ckey, _ := delivery.CandidatesKey(group(1))
+	vkey := keyOf(t, group(1), cand)
+	dc, _ := delivery.DecodeCandidate(cand)
+	judged, err := delivery.EncodeVerdict(delivery.Verdict{Group: group(1), Heads: dc.HeadsHash, Trunk: map[string]string{repoA: trunkA}, Beside: map[string]string{nodeEngineRepo: "run111"}, State: delivery.VerdictPass, Levels: passing().Levels})
+	if err != nil {
+		t.Fatal(err)
+	}
+	heads := func() (map[string]string, error) {
+		return map[string]string{repoA: trunkA, nodeEngineRepo: "trunk222"}, nil
+	}
+	for _, row := range []struct {
+		name string
+		runs runsAt
+		want int
+	}{
+		{"the running commit the verdict read", runsAt{nodeEngineModule: "run111"}, 0},
+		{"the running commit moved", runsAt{nodeEngineModule: "run999"}, 1},
+		{"no running commit known: the trunk's", nil, 1},
+	} {
+		rd := Reader{CandidateState: fakeState{ckey: cand}.read(), VerdictState: fakeState{vkey: judged}.read(), Trunks: heads}
+		if row.runs != nil {
+			rd.Runs = row.runs
+		}
+		st, err := rd.Status()
+		if err != nil {
+			t.Fatal(err)
+		}
+		if got := len(st.Waiting[KindTrunk]); got != row.want {
+			t.Errorf("%s: waiting for a trunk move = %v, want %d", row.name, st.Waiting[KindTrunk], row.want)
+		}
+	}
+}

modules/mesh-delivery-checker/internal/check/read.go

@@ -8,6 +8,7 @@ import (
 	"time"
 
 	"git.novox.be/novox/mesh-sdk/go/delivery"
+	"git.novox.be/novox/mesh-sdk/go/delivery/buildrun"
 )
 
 // The read tools (novox/hq ADR 0484 clauses 8 and 13, issue 1686): what the checker stored, as stored, with the line of the
@@ -39,7 +40,16 @@ type Reader struct {
 	StepBound    time.Duration        // how long the checker waits for one step; DefaultStepBound when 0
 	// Trunks are the trunk heads of every repository (the gate's source); nil names no re-judge after a trunk move.
 	Trunks func() (map[string]string, error)
-	Now    func() time.Time
+	// TurnState is the gate's merge turns (ADR 0548 §3); without it no check is named as held by a turn.
+	TurnState StateRead
+	// Runs says which commit the mesh runs of a module (the indexer's modules), as the checker's decision reads it: the
+	// node-engine a verdict names is compared at its running commit, not at the trunk's (ADR 0548 §6); nil knows none.
+	Runs interface{ CommitOf(module string) string }
+	// HearingState is the checker's state hearing: whether it hears DEAD_LETTERS (issue 734).
+	HearingState StateRead
+	// AskState is the checker's state asks: the asks each running check put (AsksState), which checker_ask_again reads.
+	AskState StateRead
+	Now      func() time.Time
 }
 
 // VerdictRead is a verdict as stored with the full report of the status of each pull request it judged (Report), when the
@@ -78,6 +88,11 @@ func (r Reader) read(key string, raw json.RawMessage) (VerdictRead, error) {
 	cs := CaseOf(c, v.Trunk)
 	out.Reports = map[string]string{}
 	if cs == nil {
+		if IsUntrunked(v) {
+			for _, p := range leftOf(c, v.Trunk) {
+				out.Reports[pullKey(p)] = v.Failed.Words
+			}
+		}
 		return out, nil
 	}
 	for _, p := range cs.Pulls {
@@ -293,6 +308,8 @@ type RunningStep struct {
 	ID     string `json:"id"`
 	Tool   string `json:"tool"`
 	Since  string `json:"since,omitempty"`
+	// What says what the step is (buildstep.AskWhat): an ask's kind, repository@head and levels.
+	What string `json:"what,omitempty"`
 }
 
 // LeftStep is a key a build module left running that no step behind it runs any more, and why.
@@ -312,68 +329,83 @@ type Status struct {
 	// Waiting are the candidates whose check waits, by kind (ADR 0536 §4): new (no verdict for its heads) and nodes (failed
 	// for the nodes, asked again when they change) start before trunk (judged on trunk heads that moved since).
 	Waiting map[string][]string `json:"waiting_by_kind"`
-	Notes   []string            `json:"notes,omitempty"`
+	// HeldByTurn are the candidates whose check an approved merge's turn holds off (ADR 0548 §3), by group: the repository and
+	// the group of the merge that waits. Their check is claimed when that turn goes.
+	HeldByTurn map[string]string `json:"held_by_turn"`
+	// CannotBeJudged are the candidates no pull request of which can be judged, by group, with why: the gate's source.main
+	// names no trunk head of their repositories (issue 1422). They are judged once it does; until then their status is error.
+	CannotBeJudged map[string]string `json:"cannot_be_judged"`
+	// Lost are the candidates whose verdict is running while no step of theirs can still run and their newest step ended, by
+	// group, with that step: nothing will judge them (the lost check of 2026-10-28); checker_ask_again asks one again.
+	Lost map[string]string `json:"lost"`
+	// DeadLetters says whether the checker hears the asks the build seats give up on (issue 734): deaf, a try or check
+	// whose ask is given up waits until its bound.
+	DeadLetters DeadLettersHeard `json:"dead_letters"`
+	Notes       []string         `json:"notes,omitempty"`
+}
+
+// DeadLettersHeard is the checker's hearing of DEAD_LETTERS as the status says it: healthy or not, and why.
+type DeadLettersHeard struct {
+	Heard bool   `json:"heard"`
+	Why   string `json:"why"`
+}
+
+// deadLetters reads the checker's kept hearing (buildrun.HearingHealth).
+func (r Reader) deadLetters() DeadLettersHeard {
+	if r.HearingState.Get == nil {
+		return DeadLettersHeard{Why: "the checker's state hearing is not readable here"}
+	}
+	raw, err := r.HearingState.Get(buildrun.HearingKey)
+	if err != nil {
+		return DeadLettersHeard{Why: "the checker's state hearing cannot be read: " + err.Error()}
+	}
+	a := buildrun.HearingHealth(raw)
+	return DeadLettersHeard{Heard: a.Healthy, Why: a.Why}
+}
+
+// turns reads the gate's merge turns, by repository; nil when they cannot be read, said in a note.
+func (r Reader) turns(st *Status) *Turns {
+	if r.TurnState.Keys == nil || r.TurnState.Get == nil {
+		st.Notes = append(st.Notes, "the gate's merge turns are not readable here, so no check is named as held by one")
+		return nil
+	}
+	keys, err := r.TurnState.Keys()
+	if err != nil {
+		st.Notes = append(st.Notes, "the gate's merge turns cannot be listed, so no check is named as held by one: "+err.Error())
+		return nil
+	}
+	t := &Turns{}
+	for _, k := range keys {
+		if raw, err := r.TurnState.Get(k); err == nil && len(raw) > 0 {
+			t.Put(k, raw, false)
+		}
+	}
+	return t
+}
+
+// heldBy says the turn that holds a candidate's check off, or "".
+func heldBy(t *Turns, c delivery.Candidate, heads map[string]string) string {
+	cs := CaseOf(c, heads)
+	if t == nil || cs == nil {
+		return ""
+	}
+	repos := make([]string, 0, len(cs.Trunk))
+	for r := range cs.Trunk {
+		repos = append(repos, r)
+	}
+	if repo, w, ok := t.Holding(repos, cs.Heads); ok {
+		return repo + ": the approved merge of " + w.Group + " waits on it"
+	}
+	return ""
 }
 
 // Status reads the build modules' steps and the candidates against their verdicts.
 func (r Reader) Status() (Status, error) {
-	st := Status{RunningByNode: map[string]int{}}
-	mods := make([]string, 0, len(r.StepStates))
-	for m := range r.StepStates {
-		mods = append(mods, m)
-	}
-	sort.Strings(mods)
-	st.Running, st.LeftRunning = []RunningStep{}, []LeftStep{}
-	now, bound := time.Now(), r.StepBound
-	if r.Now != nil {
-		now = r.Now()
-	}
-	if bound <= 0 {
-		bound = DefaultStepBound
-	}
-	for _, m := range mods {
-		sr := r.StepStates[m]
-		if sr.Keys == nil || sr.Get == nil {
-			continue
-		}
-		keys, err := sr.Keys()
-		if err != nil {
-			st.Notes = append(st.Notes, "the steps of "+m+" cannot be listed: "+err.Error())
-			continue
-		}
-		// A step that runs started lately: the newest ids are read first, at most MaxReads of them.
-		newestFirst(keys)
-		keys, cut := capKeys(keys, "")
-		if cut != "" {
-			st.Notes = append(st.Notes, "the steps of "+m+": read the newest "+fmt.Sprint(MaxReads)+" of its keys; a step older than those is not shown")
-		}
-		steps := make([]delivery.Step, len(keys))
-		isRunning := make([]bool, len(keys))
-		_ = parallel(len(keys), func(i int) error {
-			raw, err := sr.Get(keys[i])
-			if err != nil || len(raw) == 0 {
-				return nil
-			}
-			step, err := delivery.DecodeStep(raw)
-			steps[i], isRunning[i] = step, err == nil && step.State == delivery.StepRunning
-			return nil
-		})
-		for i := range keys {
-			if !isRunning[i] {
-				continue
-			}
-			step := steps[i]
-			rs := RunningStep{Module: m, Node: step.Node, ID: step.ID, Tool: step.Tool}
-			if !step.Started.IsZero() {
-				rs.Since = step.Started.UTC().Format("2006-01-02T15:04:05Z")
-			}
-			if why := r.leftWhy(m, step, now, bound); why != "" {
-				st.LeftRunning = append(st.LeftRunning, LeftStep{RunningStep: rs, Why: why})
-				continue
-			}
-			st.Running = append(st.Running, rs)
-			st.RunningByNode[step.Node]++
-		}
+	st := Status{RunningByNode: map[string]int{}, Lost: map[string]string{}}
+	read := r.readSteps()
+	st.Running, st.LeftRunning, st.Notes = read.running, read.left, read.notes
+	for _, rs := range st.Running {
+		st.RunningByNode[rs.Node]++
 	}
 	if r.HaveState.Get == nil {
 		st.Notes = append(st.Notes, "the node-engine's have is not readable here, so a step is not checked against its build module being on its node")
@@ -383,6 +415,8 @@ func (r Reader) Status() (Status, error) {
 	}
 	st.Unjudged = []string{}
 	st.Waiting = map[string][]string{KindNew: {}, KindNodes: {}, KindTrunk: {}}
+	st.HeldByTurn, st.CannotBeJudged = map[string]string{}, map[string]string{}
+	turns := r.turns(&st)
 	var heads map[string]string
 	if r.Trunks == nil {
 		st.Notes = append(st.Notes, "the trunk heads are not readable here, so no check is named as waiting for a trunk move")
@@ -432,27 +466,162 @@ func (r Reader) Status() (Status, error) {
 				continue
 			}
 			c, raw := row.c, row.raw
+			if heads != nil && len(leftOf(c, heads)) > 0 {
+				// Nothing of it can be judged now, whatever its verdict says (issue 1422): never counted as waiting.
+				var repos []string
+				for _, p := range leftOf(c, heads) {
+					repos = append(repos, p.Repository)
+				}
+				st.CannotBeJudged[c.Group] = UntrunkedWordsOf(repos)
+				continue
+			}
 			if len(raw) == 0 {
 				st.Unjudged = append(st.Unjudged, c.Group)
 				st.Waiting[KindNew] = append(st.Waiting[KindNew], c.Group)
+				if why := heldBy(turns, c, heads); why != "" {
+					st.HeldByTurn[c.Group] = why
+				}
 				continue
 			}
 			v, err := delivery.DecodeVerdict(raw)
 			switch {
-			case err != nil || v.State == delivery.VerdictRunning:
+			case err != nil:
+			case v.State == delivery.VerdictRunning:
+				if why := read.lostWhy(c); why != "" {
+					st.Lost[c.Group] = why
+				}
 			case IsNodesFailure(v):
 				st.Waiting[KindNodes] = append(st.Waiting[KindNodes], c.Group)
+			case IsUntrunked(v):
+				// Its trunk head is known now: it waits for its whole check.
+				st.Waiting[KindNew] = append(st.Waiting[KindNew], c.Group)
 			case heads != nil:
-				if cs := CaseOf(c, heads); cs != nil && !sameTrunk(v.Trunk, cs.Trunk) {
+				if cs := CaseOf(c, heads); cs != nil && (!sameTrunk(v.Trunk, cs.Trunk) || besideMoved(v.Beside, besideAt(heads, r.Runs))) {
 					st.Waiting[KindTrunk] = append(st.Waiting[KindTrunk], c.Group)
+					if why := heldBy(turns, c, heads); why != "" {
+						st.HeldByTurn[c.Group] = why
+					}
 				}
 			}
 		}
 	}
+	st.DeadLetters = r.deadLetters()
 	st.Notes = append(st.Notes, "nothing holds the checker and it holds no place: running_steps are the build modules' keys that can still be running (started within the step bound, their build module running on the node); a candidate without a verdict has its check ask in a build seat's stream, waiting for a node with a free slot, whose backlog the delivery view shows (ADR 0525 §4, §9)")
 	return st, nil
 }
 
+// stepsRead is what the build modules' steps states hold: the steps that can still run, those left running, and every
+// ask step read, by module, for the candidate it belongs to (stepsOf).
+type stepsRead struct {
+	running []RunningStep
+	left    []LeftStep
+	all     []moduleStep
+	notes   []string
+}
+
+type moduleStep struct {
+	module string
+	step   delivery.Step
+}
+
+// readSteps reads the newest MaxReads keys of each build module's steps state.
+func (r Reader) readSteps() stepsRead {
+	out := stepsRead{running: []RunningStep{}, left: []LeftStep{}}
+	mods := make([]string, 0, len(r.StepStates))
+	for m := range r.StepStates {
+		mods = append(mods, m)
+	}
+	sort.Strings(mods)
+	now, bound := time.Now(), r.StepBound
+	if r.Now != nil {
+		now = r.Now()
+	}
+	if bound <= 0 {
+		bound = DefaultStepBound
+	}
+	for _, m := range mods {
+		sr := r.StepStates[m]
+		if sr.Keys == nil || sr.Get == nil {
+			continue
+		}
+		keys, err := sr.Keys()
+		if err != nil {
+			out.notes = append(out.notes, "the steps of "+m+" cannot be listed: "+err.Error())
+			continue
+		}
+		// A step that runs started lately: the newest ids are read first, at most MaxReads of them.
+		newestFirst(keys)
+		keys, cut := capKeys(keys, "")
+		if cut != "" {
+			out.notes = append(out.notes, "the steps of "+m+": read the newest "+fmt.Sprint(MaxReads)+" of its keys; a step older than those is not shown")
+		}
+		steps := make([]delivery.Step, len(keys))
+		decoded := make([]bool, len(keys))
+		_ = parallel(len(keys), func(i int) error {
+			raw, err := sr.Get(keys[i])
+			if err != nil || len(raw) == 0 {
+				return nil
+			}
+			step, err := delivery.DecodeStep(raw)
+			steps[i], decoded[i] = step, err == nil
+			return nil
+		})
+		for i := range keys {
+			if !decoded[i] {
+				continue
+			}
+			step := steps[i]
+			out.all = append(out.all, moduleStep{module: m, step: step})
+			if step.State != delivery.StepRunning {
+				continue
+			}
+			rs := RunningStep{Module: m, Node: step.Node, ID: step.ID, Tool: step.Tool, What: step.What}
+			if !step.Started.IsZero() {
+				rs.Since = step.Started.UTC().Format("2006-01-02T15:04:05Z")
+			}
+			if why := r.leftWhy(m, step, now, bound); why != "" {
+				out.left = append(out.left, LeftStep{RunningStep: rs, Why: why})
+				continue
+			}
+			out.running = append(out.running, rs)
+		}
+	}
+	return out
+}
+
+// asksOf says whether a step is an ask of one of the candidate's pull requests: its What names `<repository>@<head12>`
+// (buildstep.AskWhat).
+func asksOf(c delivery.Candidate, what string) bool {
+	for _, p := range c.Pulls {
+		if p.Repository != "" && strings.Contains(what, p.Repository+"@"+short12(p.Head.Head)) {
+			return true
+		}
+	}
+	return false
+}
+
+// lostWhy says why a candidate whose verdict is running has a check that nothing will judge, or "": no step of its pull
+// requests can still run, and its newest one ended.
+func (s stepsRead) lostWhy(c delivery.Candidate) string {
+	for _, rs := range s.running {
+		if asksOf(c, rs.What) {
+			return ""
+		}
+	}
+	var last *delivery.Step
+	for i := range s.all {
+		st := s.all[i].step
+		if st.State != delivery.StepRunning && asksOf(c, st.What) && (last == nil || st.Ended.After(last.Ended)) {
+			last = &s.all[i].step
+		}
+	}
+	if last == nil {
+		return "" // its ask waits in its build seat's stream: no node took it yet
+	}
+	return fmt.Sprintf("its verdict is running, but no step of it runs: its last step %s on %s ended %s at %s and no verdict followed; %s asks it again",
+		last.ID, last.Node, last.State, last.Ended.UTC().Format(time.RFC3339), AskAgainTool)
+}
+
 // DefaultStepBound is how long one check ask's step may run once a build node took it (its key written running; the fetch,
 // the digests and the levels), never counting its wait in the stream; past it the check fails naming the node.
 const DefaultStepBound = 30 * time.Minute

modules/mesh-delivery-checker/internal/check/read_test.go

@@ -36,6 +36,7 @@ func (f fakeState) read() StateRead {
 func readerOf(t *testing.T) (Reader, string) {
 	t.Helper()
 	r := newRig(t, passJudge())
+	r.setTrunks(t, map[string]string{repoA: trunkA, repoSDK: trunkS, hqRepo: trunkA2})
 	cand := candidateOf(t, "feat/x", pullOf(repoA, 7, head1), pullOf(hqRepo, 3, head2))
 	r.ch.Candidate(context.Background(), "feat%2Fx", cand)
 	r.ch.Wait()
@@ -144,7 +145,10 @@ func TestTheStatusToolReadsRunningSteps(t *testing.T) {
 		CandidateState: fakeState{ckey: cand}.read(),
 		VerdictState:   fakeState{}.read(),
 		HaveState:      fakeState{"shanks.mesh-build-go": haveOf(t, delivery.PhaseRunning)}.read(),
-		Now:            func() time.Time { return time.Date(2026, 10, 22, 15, 10, 0, 0, time.UTC) },
+		HearingState: fakeState{"dead-letters": []byte(`{"heard":false,"streams":["SEAT_NODE_BUILD_GO"],` +
+			`"why":"DEAD_LETTERS is not heard, so an ask a build seat gives up on is waited for until its bound: SEAT_NODE_BUILD_GO: permissions violation",` +
+			`"at":"2026-10-26T13:00:00Z"}`)}.read(),
+		Now: func() time.Time { return time.Date(2026, 10, 22, 15, 10, 0, 0, time.UTC) },
 	}
 	st, err := rd.Status()
 	if err != nil {
@@ -156,9 +160,13 @@ func TestTheStatusToolReadsRunningSteps(t *testing.T) {
 	if len(st.Unjudged) != 1 || st.Unjudged[0] != "feat/x" {
 		t.Errorf("unjudged = %v", st.Unjudged)
 	}
+	// Issue 734, review round 1: a checker that does not hear DEAD_LETTERS says so in its status, with why.
+	if st.DeadLetters.Heard || !strings.Contains(st.DeadLetters.Why, "permissions violation") {
+		t.Errorf("dead letters = %+v, want not heard, saying why", st.DeadLetters)
+	}
 	// What cannot be read is said, not guessed.
 	st, err = Reader{}.Status()
-	if err != nil || len(st.Notes) == 0 {
+	if err != nil || len(st.Notes) == 0 || st.DeadLetters.Heard {
 		t.Errorf("empty status = %+v, %v", st, err)
 	}
 }
@@ -234,6 +242,18 @@ func TestTheStatusCountsAnHQOnlyGroupAsUnjudged(t *testing.T) {
 	if len(st.Unjudged) != 1 || st.Unjudged[0] != "pb-x" {
 		t.Errorf("unjudged = %v, want pb-x", st.Unjudged)
 	}
+	// ADR 0548 §3: a candidate whose check an approved merge's turn holds off is named with the turn.
+	held := candidateOf(t, "feat/x", pullOf(repoA, 7, head1))
+	hkey, _ := delivery.CandidatesKey("feat/x")
+	st, err = Reader{CandidateState: fakeState{hkey: held}.read(), VerdictState: fakeState{}.read(),
+		Trunks:    func() (map[string]string, error) { return map[string]string{repoA: trunkA}, nil },
+		TurnState: fakeState{turnKey(t, repoA): turnOf(t, repoA, "fix/other", "0123456789ab")}.read()}.Status()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if why := st.HeldByTurn["feat/x"]; !strings.Contains(why, repoA) || !strings.Contains(why, "fix/other") {
+		t.Errorf("held_by_turn = %v, want feat/x held by the merge of fix/other on %s", st.HeldByTurn, repoA)
+	}
 }
 
 // slowBucket wraps a state with a Get that takes delay and counts the values read, the lists and the most Gets in flight.

modules/mesh-delivery-checker/internal/check/results.go

@@ -3,6 +3,9 @@ package check
 import (
 	"encoding/json"
 	"strings"
+
+	"git.novox.be/novox/mesh-sdk/go/buildstep"
+	"git.novox.be/novox/mesh-sdk/go/delivery"
 )
 
 // The shapes of what the build modules' steps answer, as their code writes them (mesh-catalog modules/mesh-build-go
@@ -42,6 +45,17 @@ type Fetched struct {
 	Conflicts []string             `json:"conflicts,omitempty"`
 	Changed   []string             `json:"changed,omitempty"`
 	Trees     map[string]MergeTree `json:"trees,omitempty"`
+	// Programs are the changed files whose first bytes are an executable binary, read by the build module in its workspace
+	// (issue 1577); nil for a build module that does not report it, a pointer to an empty list for one that found none.
+	Programs *[]ProgramFile `json:"programs,omitempty"`
+}
+
+// ProgramFile is a changed file that is a compiled program, and its format (ELF, Mach-O or PE).
+type ProgramFile struct {
+	Path string `json:"path"`
+	Kind string `json:"kind"`
+	// Commit is set for a program a commit of the branch added and a later one removed: it stays in history once merged.
+	Commit string `json:"commit,omitempty"`
 }
 
 // GoPackage is one package of a Go test result.
@@ -52,16 +66,13 @@ type GoPackage struct {
 	Elapsed float64 `json:"elapsed"`
 	Tests   int     `json:"tests"`
 	NoTests bool    `json:"no_tests,omitempty"`
+	// Skipped is how many of the package's tests skipped; an older build module names none.
+	Skipped int `json:"skipped,omitempty"`
 }
 
-// Failure is a test that failed, or a package that failed with no test to name.
-type Failure struct {
-	Package string `json:"package"`
-	Test    string `json:"test,omitempty"`
-	Output  string `json:"output,omitempty"`
-	// Cause is the first line of what the test reported as its error, when the build module told it apart (issue 1901).
-	Cause string `json:"cause,omitempty"`
-}
+// Failure is a test that failed, or a package that failed with no test to name: the build modules' failure contract
+// (buildstep.Failure, issue 1901), its cause never empty and never a passing line from a build module that keeps it.
+type Failure = buildstep.Failure
 
 // TestTime is one test and the seconds it took.
 type TestTime struct {
@@ -94,6 +105,9 @@ type Tested struct {
 	// JudgedBy is the program that ran the step (ADR 0535 §5): "installed", or "candidate <merge commit>" under runner
 	// workspace; absent from a build module that does not take the runner.
 	JudgedBy string `json:"judged_by,omitempty"`
+	// By is the build module that answered and the SDK it was built with (buildstep.By); absent from a build module from
+	// before the failure contract.
+	By string `json:"by,omitempty"`
 }
 
 // Digested is the answer of the Go build module's digest step: one digest per package that has tests at the level, by import
@@ -107,4 +121,6 @@ type Digested struct {
 	WithoutTests []string          `json:"without_tests,omitempty"`
 	// JudgedBy is the program that ran the digest, as Tested.JudgedBy says.
 	JudgedBy string `json:"judged_by,omitempty"`
+	// Needs are the packages whose tests need something of the node at this level (issue 890).
+	Needs []delivery.PackageNeeds `json:"needs,omitempty"`
 }

modules/mesh-delivery-checker/internal/check/testdata/captured/README

@@ -10,7 +10,7 @@ TestFetchWithABaseMergesAndAnswersThePreview and TestFetchWithAConflictEndsPasse
 into a throwaway test that wrote them out, at mesh-catalog feat/r4c5-checker d5804927 (the git commands are the test's fake,
 so the shas are its constants; the shape and the field names are the module's own marshalling). node-fetch-clean.json is the
 FetchResult json.Marshal of mesh-build-node's fetch (fetch.go, preview.go) in its test TestFetchWithABaseMergesAndAnswersThePreview
-(cmd/mesh-build-node/preview_test.go) at the same commit. Captured on 2026-10-21 for issue 1679.
+(cmd/mesh-build-node/preview_test.go) at the same commit. Captured on 2026-10-21 for issue 1679. Both clean fetches carry `"programs":[]`, which a merging fetch of the build modules answers since issue 1577 (mesh-sdk buildstep.MergeInto's Programs), added by hand to the captured bytes: a fixture without it is an older build module's, and its line warns that no compiled program is refused.
 
 forge-get-file-go-mod.json is the answer of the forge's gitea_get_file (mesh-catalog modules/gitea, tools/index.ts) for modules/mesh-delivery-builder/go.mod of
 novox/mesh-delivery at main, and forge-compare-trunk.json the answer of gitea_compare for novox/mesh-sdk base main, head cb54756c3865 (a commit on the

modules/mesh-delivery-checker/internal/check/testdata/captured/go-fetch-clean.json

@@ -1 +1 @@
-{"workspace":"mvii1iwu5414e4","commit":"0123456789abcdef0123456789abcdef01234567","modules":["."],"base":"abcdef0123456789abcdef0123456789abcdef01","merge":"fedcba9876543210fedcba9876543210fedcba98","changed":["a.go","modules/m/main.go"],"trees":{"modules/m":{"tree":"1111111111111111111111111111111111111111","manifest":"ca3d163bab055381827226140568f3bef7eaac187cebd76878e0b63e9e442356","locks":{"go.sum":"c5fc83c01e92404452b986527d239140ccf9a48b88e0c268fbf38c2e1429e9c9"}}}}
+{"workspace":"mvii1iwu5414e4","commit":"0123456789abcdef0123456789abcdef01234567","modules":["."],"base":"abcdef0123456789abcdef0123456789abcdef01","merge":"fedcba9876543210fedcba9876543210fedcba98","changed":["a.go","modules/m/main.go"],"programs":[],"trees":{"modules/m":{"tree":"1111111111111111111111111111111111111111","manifest":"ca3d163bab055381827226140568f3bef7eaac187cebd76878e0b63e9e442356","locks":{"go.sum":"c5fc83c01e92404452b986527d239140ccf9a48b88e0c268fbf38c2e1429e9c9"}}}}

modules/mesh-delivery-checker/internal/check/testdata/captured/node-fetch-clean.json

@@ -1 +1 @@
-{"workspace":"mvii1sxt979f67","commit":"0123456789abcdef0123456789abcdef01234567","modules":["modules/m"],"installed":[],"refused":[],"base":"abcdef0123456789abcdef0123456789abcdef01","merge":"0123456789abcdef0123456789abcdef01234567","changed":["modules/m/package.json"],"trees":{"modules/m":{"tree":"0123456789abcdef0123456789abcdef01234567","manifest":"0581b699d9d05517e69b21f5cedbeb2eee8aba2b205280b561be731594d7feef"}}}
+{"workspace":"mvii1sxt979f67","commit":"0123456789abcdef0123456789abcdef01234567","modules":["modules/m"],"installed":[],"refused":[],"base":"abcdef0123456789abcdef0123456789abcdef01","merge":"0123456789abcdef0123456789abcdef01234567","changed":["modules/m/package.json"],"programs":[],"trees":{"modules/m":{"tree":"0123456789abcdef0123456789abcdef01234567","manifest":"0581b699d9d05517e69b21f5cedbeb2eee8aba2b205280b561be731594d7feef"}}}

modules/mesh-delivery-checker/internal/check/try.go

@@ -6,6 +6,7 @@ import (
 	"errors"
 	"fmt"
 	"regexp"
+	"slices"
 	"sort"
 	"strconv"
 	"strings"
@@ -13,6 +14,7 @@ import (
 	"time"
 
 	"git.novox.be/novox/mesh-sdk/go/delivery"
+	"git.novox.be/novox/mesh-sdk/go/delivery/buildrun"
 )
 
 // A try is a pushed head judged by the checker as a pull request's head is, before its pull request is opened (ADR 0501
@@ -24,11 +26,17 @@ import (
 const (
 	TryTool     = "checker_try"
 	TryReadTool = "checker_try_read"
+	TryEndTool  = "checker_try_end"
 	// TriesState is the checker's state of tries: the bucket mesh-delivery-checker_tries, keys try-<unix nanoseconds>.
 	TriesState  = "tries"
 	TriesBucket = delivery.CheckerModule + "_" + TriesState
-	// MaxTries is how many tries may wait or run at once, mesh-wide: each holds a build node for minutes.
-	MaxTries = 4
+	// MaxTries and MaxTriesWaiting are checked when a try is asked, mesh-wide: a new try is refused while MaxTries tries run
+	// on a build node or MaxTriesWaiting wait for one (queued, or their asks not yet taken by a node). It is no bound on
+	// what runs later: tries let in while waiting may later all run at once, and each node's build capacity bounds what
+	// runs on it. A try waiting behind the seat's other asks holds no node, so it no longer blocks the next try (issue
+	// 1890: at 19:53 on 2026-10-26 four tries sat queued behind 44 checks for up to 47 minutes and no fifth could be asked).
+	MaxTries        = 4
+	MaxTriesWaiting = 8
 	// TryScan is how many of the newest tries a new ask reads to find the ones that wait or run (issue 1827).
 	TryScan = 64
 	// TryKeep is how long an ended try's key is kept before the checker removes it.
@@ -69,13 +77,110 @@ type Try struct {
 	// Said is the try's report in words: what failed first, the tests run, kept and skipped per level, the time of each part.
 	Said string `json:"said,omitempty"`
 	// Took is the time from its start to its end, as Go writes a duration.
-	Took     string                          `json:"took,omitempty"`
+	Took string `json:"took,omitempty"`
+	// Failed is every test that failed, each with its first line, at most delivery.MaxFailures and then how many more
+	// (issue 1921); or what else failed first (a conflict, a refused step).
 	Failed   []string                        `json:"failed,omitempty"`
 	Levels   map[string]delivery.LevelResult `json:"levels,omitempty"`
 	Machines []string                        `json:"machines,omitempty"`
-	Asked    time.Time                       `json:"asked"`
-	Started  time.Time                       `json:"started,omitzero"`
-	Ended    time.Time                       `json:"ended,omitzero"`
+	// Asks are the ids of the asks the try put on the build seats' streams, each ending on the step key <node>.<id> of its
+	// build module: the delivery view counts those steps as a try's, not a candidate's check (build_usage).
+	Asks []string `json:"asks,omitempty"`
+	// Steps say where each ask stands while the try runs and after: asked until a node takes it, then the node, its
+	// state, the phase its step says and when (issue 1890: a 31-minute try could not be told queued from running).
+	Steps   []TryStep `json:"steps,omitempty"`
+	Asked   time.Time `json:"asked"`
+	Started time.Time `json:"started,omitzero"`
+	Ended   time.Time `json:"ended,omitzero"`
+}
+
+// TryAsked is a TryStep's state before a build node took its ask: it waits in the seat's stream.
+const TryAsked = "asked"
+
+// TryStep is one ask of a try as its step key last said it.
+type TryStep struct {
+	Ask     string    `json:"ask"`
+	Node    string    `json:"node,omitempty"`
+	State   string    `json:"state"`
+	Phase   string    `json:"phase,omitempty"`
+	Started time.Time `json:"started,omitzero"`
+	PhaseAt time.Time `json:"phase-at,omitzero"`
+	Ended   time.Time `json:"ended,omitzero"`
+}
+
+// tryWriter writes a running try's record again as its asks are put and their steps move: one writer per try, holding
+// the revision it wrote last, so the try's end is written at that revision. A write refused (the try ended by hand)
+// stops the writes; the end's own write then says it.
+type tryWriter struct {
+	mu      sync.Mutex
+	tr      *Tryer
+	ctx     context.Context
+	key     string
+	t       Try
+	rev     uint64
+	stopped bool
+}
+
+// heard takes an ask put (step nil) or a value of its step key in, and writes the record when it changed.
+func (w *tryWriter) heard(askID string, step *delivery.Step) {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+	if w.stopped {
+		return
+	}
+	changed := false
+	if !slices.Contains(w.t.Asks, askID) {
+		w.t.Asks, changed = append(w.t.Asks, askID), true
+	}
+	i := slices.IndexFunc(w.t.Steps, func(s TryStep) bool { return s.Ask == askID })
+	if i < 0 {
+		w.t.Steps, changed = append(w.t.Steps, TryStep{Ask: askID, State: TryAsked}), true
+		i = len(w.t.Steps) - 1
+	}
+	if step != nil {
+		now := TryStep{Ask: askID, Node: step.Node, State: step.State, Phase: step.Phase, Started: step.Started,
+			PhaseAt: step.PhaseAt, Ended: step.Ended}
+		changed = changed || now != w.t.Steps[i]
+		w.t.Steps[i] = now
+	}
+	if changed {
+		w.write()
+	}
+}
+
+// write writes the record at the revision written last; a refusal stops the writes.
+func (w *tryWriter) write() {
+	data, err := encodeTry(w.t)
+	if err != nil {
+		return
+	}
+	rev, err := w.tr.Tries.Update(w.ctx, w.key, data, w.rev)
+	if err != nil {
+		w.stopped = true
+		w.tr.logf("%s: its asks' progress is no longer written: %v", w.key, err)
+		return
+	}
+	w.rev = rev
+}
+
+// end stops the writes and answers the record and its revision, for the try's end.
+func (w *tryWriter) end() (Try, uint64) {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+	w.stopped = true
+	return w.t, w.rev
+}
+
+// HoldsANode says whether the try holds a build node now: it runs, and a step of its asks runs on a node, or it names
+// no step (a checker that writes its asks only at the end, or one about to put its first).
+func (t Try) HoldsANode() bool {
+	if t.State != TryRunning {
+		return false
+	}
+	if len(t.Steps) == 0 {
+		return true
+	}
+	return slices.ContainsFunc(t.Steps, func(s TryStep) bool { return s.State == delivery.StepRunning })
 }
 
 // Over says whether the try came to its end.
@@ -117,8 +222,8 @@ func NotChecked(repository string) error {
 }
 
 // AskTry writes a new try, queued, and answers its id: a try of the same head that waits or runs is the answer to a second
-// ask, and at most MaxTries wait or run at once. trunks are the gate's trunk heads of every repository (source.main): a
-// repository with none is no repository the checker checks. A trunk asked by name is its trunk head now.
+// ask, and a new try is refused while MaxTries tries run on a build node or MaxTriesWaiting wait for one. trunks are the
+// gate's trunk heads of every repository (source.main): a repository with none is no repository the checker checks. A trunk asked by name is its trunk head now.
 func AskTry(store TryStore, trunks map[string]string, a TryAsk, now time.Time) (string, error) {
 	repo := strings.ToLower(strings.TrimSuffix(strings.TrimSpace(a.Repository), ".git"))
 	head := strings.ToLower(strings.TrimSpace(a.Head))
@@ -181,7 +286,7 @@ func AskTry(store TryStore, trunks map[string]string, a TryAsk, now time.Time) (
 	}); err != nil {
 		return "", err
 	}
-	var open []string
+	var holding, waiting []string
 	for i, cur := range tries {
 		if !live[i] {
 			continue
@@ -189,10 +294,18 @@ func AskTry(store TryStore, trunks map[string]string, a TryAsk, now time.Time) (
 		if cur.Repository == t.Repository && cur.Head == t.Head && cur.Trunk == t.Trunk && cur.Tests == t.Tests && cur.Level == t.Level {
 			return cur.ID, nil
 		}
-		open = append(open, fmt.Sprintf("%s (%s@%.12s, %s)", cur.ID, cur.Repository, cur.Head, cur.State))
+		said := fmt.Sprintf("%s (%s@%.12s, %s)", cur.ID, cur.Repository, cur.Head, cur.State)
+		if cur.HoldsANode() {
+			holding = append(holding, said)
+		} else {
+			waiting = append(waiting, said)
+		}
 	}
-	if len(open) >= MaxTries {
-		return "", fmt.Errorf("%d tries wait or run, the most at once: %s; ask again when one ends", len(open), strings.Join(open, ", "))
+	// Checked at this ask only: a try queued behind the seat's checks holds no node; tries let in while waiting may later
+	// all run at once, and each node's build capacity bounds what runs on it.
+	if len(holding) >= MaxTries || len(waiting) >= MaxTriesWaiting {
+		return "", fmt.Errorf("a new try is refused while %d tries run on a build node or %d wait for one; now %d run and %d wait: running %s; waiting %s; ask again when one ends",
+			MaxTries, MaxTriesWaiting, len(holding), len(waiting), orNone(holding), orNone(waiting))
 	}
 	t.ID = "try-" + strconv.FormatInt(now.UnixNano(), 10)
 	data, err := encodeTry(t)
@@ -220,6 +333,52 @@ func ReadTry(store TryStore, id string) (json.RawMessage, error) {
 	return raw, nil
 }
 
+// TryEnder is the tries state as the end tool sees it: one key with its revision, and a write at that revision.
+type TryEnder interface {
+	Entry(key string) (json.RawMessage, uint64, error)
+	Update(key string, value []byte, revision uint64) error
+}
+
+// EndTry ends a try that waits or runs as error, saying why and that it was ended by hand (issue 734): its place is
+// free at once, and the next checker_try of its head asks anew. A try that ended already is refused, naming its end.
+func EndTry(store TryEnder, id, why string, now time.Time) (Try, error) {
+	if !tryKeyOK.MatchString(id) {
+		return Try{}, fmt.Errorf("%q is not a try's id, try-<digits>", id)
+	}
+	why = strings.TrimSpace(why)
+	if why == "" {
+		return Try{}, errors.New("say why the try is ended: the why is kept in what it says")
+	}
+	raw, rev, err := store.Entry(id)
+	if err != nil {
+		return Try{}, err
+	}
+	if len(raw) == 0 {
+		return Try{}, fmt.Errorf("no try %s: it was never asked, or it ended more than %s ago and was removed", id, TryKeep)
+	}
+	t, err := DecodeTry(raw)
+	if err != nil {
+		return Try{}, err
+	}
+	if t.Over() {
+		return Try{}, fmt.Errorf("%s ended already, %s at %s", id, t.State, t.Ended.Format(time.RFC3339))
+	}
+	t.State, t.Ended = TryError, now.UTC()
+	if !t.Started.IsZero() {
+		t.Took = t.Ended.Sub(t.Started).Round(time.Second).String()
+	}
+	t.Said = strings.TrimSpace("ended by hand (" + TryEndTool + "): " + why + " | " + t.Said)
+	t.Said = strings.TrimSuffix(t.Said, " |")
+	data, err := encodeTry(t)
+	if err != nil {
+		return Try{}, err
+	}
+	if err := store.Update(id, data, rev); err != nil {
+		return Try{}, fmt.Errorf("%s changed while it was ended, read it and end it again: %w", id, err)
+	}
+	return t, nil
+}
+
 // TryOptions narrow what a try runs; a pull request's check has none.
 type TryOptions struct {
 	Level string
@@ -232,12 +391,14 @@ type Tryer struct {
 	Tries KV
 	Judge Judge
 	Bound time.Duration
-	Now   func() time.Time
-	Logf  func(format string, args ...any)
+	// NotTaken ends a try whose ask no build node took within it as error (issue 734); none when 0.
+	NotTaken time.Duration
+	Now      func() time.Time
+	Logf     func(format string, args ...any)
 
 	mu       sync.Mutex
 	wg       sync.WaitGroup
-	inflight map[string]bool
+	inflight map[string]context.CancelFunc
 	seen     map[string]bool // looked at since this process started: a try left running is taken over the first time
 }
 
@@ -265,25 +426,31 @@ func (tr *Tryer) Put(ctx context.Context, key string, value []byte) {
 		tr.logf("tries.%s holds what is not a try, left: %v", key, err)
 		return
 	}
-	if t.Over() {
-		return
-	}
 	tr.mu.Lock()
 	if tr.inflight == nil {
-		tr.inflight, tr.seen = map[string]bool{}, map[string]bool{}
+		tr.inflight, tr.seen = map[string]context.CancelFunc{}, map[string]bool{}
 	}
-	if tr.inflight[key] || (t.State == TryRunning && tr.seen[key]) {
+	if t.Over() {
+		// Ended while it ran (checker_try_end): its judging stops, and its asks are no longer waited for.
+		if stop := tr.inflight[key]; stop != nil {
+			stop()
+		}
 		tr.mu.Unlock()
 		return
 	}
+	if tr.inflight[key] != nil || (t.State == TryRunning && tr.seen[key]) {
+		tr.mu.Unlock()
+		return
+	}
+	run, stop := context.WithCancel(ctx)
 	tr.seen[key] = true
-	tr.inflight[key] = true
+	tr.inflight[key] = stop
 	tr.mu.Unlock()
 	tr.wg.Add(1)
 	go func() {
 		defer tr.wg.Done()
-		defer func() { tr.mu.Lock(); delete(tr.inflight, key); tr.mu.Unlock() }()
-		tr.run(ctx, key)
+		defer func() { tr.mu.Lock(); delete(tr.inflight, key); tr.mu.Unlock(); stop() }()
+		tr.run(run, key)
 	}()
 }
 
@@ -334,34 +501,42 @@ func (tr *Tryer) run(ctx context.Context, key string) {
 		}
 		return
 	}
-	cs := &Case{Key: key, Group: key,
+	progress := &tryWriter{tr: tr, ctx: ctx, key: key, t: t, rev: rev}
+	cs := &Case{Key: key, Group: key, Watch: progress.heard,
 		Pulls:    []Pull{{Repository: t.Repository, Head: t.Head, Trunk: t.Trunk}},
 		Trunk:    map[string]string{t.Repository: t.Trunk},
 		Queued:   t.Asked,
 		Progress: &Progress{},
 		Try:      &TryOptions{Level: t.Level, Run: t.Tests}}
-	out, judged := judgeWithin(ctx, tr.Judge, cs, tr.Bound)
-	if ctx.Err() != nil {
-		return // left running: the checker takes it over when it starts
+	judging := ctx
+	if tr.NotTaken > 0 {
+		judging = buildrun.NotTakenBound(ctx, tr.NotTaken)
 	}
+	out, judged := judgeWithin(judging, tr.Judge, cs, tr.Bound)
+	if ctx.Err() != nil {
+		return // left running: the checker takes it over when it starts; or ended by hand, which wrote its end
+	}
+	t, rev = progress.end()
 	v := out.Verdict
 	t.Ended = tr.now().UTC()
 	t.Took = t.Ended.Sub(t.Started).Round(time.Second).String()
-	t.Levels, t.Machines = v.Levels, v.Machines
+	t.Levels, t.Machines, t.Asks = v.Levels, v.Machines, cs.Asks()
 	t.Said = Report(v, cs, cs.Pulls[0], out.Builds, out.Slowest, out.Judged)
 	for _, n := range cs.Notes() {
 		t.Said += " | " + n
 	}
 	switch {
-	case !judged || IsNodesFailure(v):
+	case !judged || IsNodesFailure(v) || IsLostAsk(v) || IsNotTaken(v):
+		// Not the change's: its ask was given up or never taken (issue 734), or a part of the mesh was not heard.
 		t.State = TryError
+		if IsLostAsk(v) || IsNotTaken(v) {
+			t.Failed = []string{v.Failed.Words}
+		}
 	case v.State == delivery.VerdictPass:
 		t.State = TryPass
 	default:
 		t.State = TryFail
-		if f := firstFailed(v); f != "" {
-			t.Failed = []string{f}
-		}
+		t.Failed = failedLines(v)
 	}
 	if t.Tests != "" {
 		t.Said += " | only the tests " + t.Tests + " (Go); nothing kept"
@@ -403,3 +578,11 @@ func judgeWithin(ctx context.Context, j Judge, cs *Case, bound time.Duration) (O
 	}
 	return out, true
 }
+
+// orNone joins the tries said, or says none.
+func orNone(said []string) string {
+	if len(said) == 0 {
+		return "none"
+	}
+	return strings.Join(said, ", ")
+}

modules/mesh-delivery-checker/internal/check/try_test.go

@@ -3,6 +3,7 @@ package check
 import (
 	"context"
 	"encoding/json"
+	"fmt"
 	"strings"
 	"testing"
 	"time"
@@ -23,6 +24,19 @@ func (m memTries) Create(key string, value []byte) error {
 	return err
 }
 
+// writtenTries is a memKV that keeps every running try it was given to write, in order.
+type writtenTries struct {
+	*memKV
+	running []Try
+}
+
+func (w *writtenTries) Update(ctx context.Context, key string, value []byte, rev uint64) (uint64, error) {
+	if t, err := DecodeTry(value); err == nil && !t.Over() {
+		w.running = append(w.running, t)
+	}
+	return w.memKV.Update(ctx, key, value, rev)
+}
+
 var tryTrunks = map[string]string{repoA: trunkA, repoSDK: trunkS, hqRepo: trunkA}
 
 func readTry(t testing.TB, kv *memKV, id string) Try {
@@ -54,14 +68,38 @@ func TestATryIsAskedQueuedOncePerHeadAndAtMostFourAtOnce(t *testing.T) { // ADR
 	if err != nil || again != id {
 		t.Errorf("a second ask of the same head answered %q, %v, want %q", again, err, id)
 	}
-	heads := []string{head2, trunkA2, trunkS2}
-	for i, h := range heads {
-		if _, err := AskTry(store, tryTrunks, TryAsk{Repository: repoA, Head: h, Trunk: trunkA}, at.Add(time.Duration(i+2)*time.Second)); err != nil {
-			t.Fatalf("try %d: %v", i+2, err)
-		}
+	// Issue 1890: tries on a build node (a step of theirs running, or none named yet) and tries waiting for one (queued, or
+	// their asks not taken) are bounded apart, MaxTries and MaxTriesWaiting; the refusal names both counts.
+	onNode := func(i int) Try {
+		return Try{ID: fmt.Sprintf("try-%d", i), Repository: repoA, Head: fmt.Sprintf("%040x", i), Trunk: trunkA, State: TryRunning,
+			Steps: []TryStep{{Ask: "a", State: delivery.StepRunning}}}
 	}
-	if _, err := AskTry(store, tryTrunks, TryAsk{Repository: repoSDK, Head: head1}, at.Add(time.Minute)); err == nil || !strings.Contains(err.Error(), "4 tries wait or run") {
-		t.Errorf("a fifth try answered %v, want refused naming the four", err)
+	waitingFor := func(i int) Try {
+		return Try{ID: fmt.Sprintf("try-%d", i), Repository: repoA, Head: fmt.Sprintf("%040x", i), Trunk: trunkA, State: TryRunning,
+			Steps: []TryStep{{Ask: "a", State: TryAsked}}}
+	}
+	for _, c := range []struct {
+		what          string
+		holding, wait int
+		refused       string
+	}{
+		{"four queued behind the checks, none on a node: a fifth is taken", 0, 4, ""},
+		{"four on a node", MaxTries, 0, "now 4 run and 0 wait"},
+		{"three on a node, eight waiting", 3, MaxTriesWaiting, "a new try is refused while 4 tries run on a build node or 8 wait for one; now 3 run and 8 wait"},
+	} {
+		kv := newMemKV()
+		for i := range c.holding + c.wait {
+			tr := waitingFor(i + 1)
+			if i < c.holding {
+				tr = onNode(i + 1)
+			}
+			data, _ := encodeTry(tr)
+			_, _ = kv.Create(context.Background(), tr.ID, data)
+		}
+		_, err := AskTry(memTries{kv}, tryTrunks, TryAsk{Repository: repoSDK, Head: head1}, at.Add(time.Minute))
+		if (c.refused == "") != (err == nil) || (err != nil && !strings.Contains(err.Error(), c.refused)) {
+			t.Errorf("%s: answered %v, want refused %q", c.what, err, c.refused)
+		}
 	}
 }
 
@@ -89,7 +127,8 @@ func TestATryIsJudgedAsAPullRequestsHeadAndOwesTheForgeNothing(t *testing.T) { /
 		t.Fatal(err)
 	}
 	b := newBench(t)
-	tr := &Tryer{Tries: kv, Judge: b.ex}
+	written := &writtenTries{memKV: kv}
+	tr := &Tryer{Tries: written, Judge: b.ex}
 	raw, _, _, _ := kv.Get(ctx, id)
 	tr.Put(ctx, id, raw)
 	tr.Wait()
@@ -97,6 +136,21 @@ func TestATryIsJudgedAsAPullRequestsHeadAndOwesTheForgeNothing(t *testing.T) { /
 	if got.State != TryPass || got.Took == "" || got.Head != head1 || got.Trunk != trunkA || got.Said == "" || got.Levels[delivery.LevelUnit].Run != 2 {
 		t.Fatalf("try = %+v", got)
 	}
+	// Issue 1890: while it runs, the try names its ask as soon as it is put, and then where its step stands; the end
+	// keeps each ask's node and state.
+	if len(written.running) < 3 || len(written.running[1].Asks) != 1 || written.running[1].Steps[0].State != TryAsked ||
+		written.running[2].Steps[0].Node != "shanks" {
+		t.Errorf("the running try's writes = %+v, want its ask named while it ran, then its node", written.running)
+	}
+	if len(got.Steps) != 1 || got.Steps[0].Node != "shanks" || got.Steps[0].State != delivery.StepPassed {
+		t.Errorf("the ended try's steps = %+v", got.Steps)
+	}
+	// The try names the asks it put, so the delivery view counts their steps as a try's (build_usage).
+	if len(got.Asks) != 1 {
+		t.Errorf("asks = %v, want the one check ask the try put", got.Asks)
+	} else if _, err := delivery.AskStepKey("shanks", got.Asks[0]); err != nil {
+		t.Errorf("the try names %q, which is no ask id: %v", got.Asks[0], err)
+	}
 	fetch := b.steps.tool("fetch")
 	if len(fetch) != 1 || fetch[0].args["commit"] != head1 || fetch[0].args["base"] != trunkA || fetch[0].args["ref"] != "" {
 		t.Errorf("fetch = %+v, want the head merged onto the trunk, with no pull request's ref", fetch)

modules/mesh-delivery-checker/internal/check/turns.go

@@ -0,0 +1,78 @@
+package check
+
+import (
+	"sort"
+	"strings"
+	"sync"
+
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+)
+
+// Turns holds the gate's merge turns (novox/hq ADR 0548 §3), by repository, as a watch of the gate's turns bucket puts them
+// in: the checker claims no check of a repository a turn names, except the check of a waiting delivery's own heads, so an
+// approved merge goes before a check not yet started. A bucket not there is read as empty.
+type Turns struct {
+	mu     sync.Mutex
+	byRepo map[string]delivery.Turn
+}
+
+// Put takes a value of the turns bucket in, or its delete, and answers whether what the checker holds changed. A value that
+// is not a turn is dropped as a delete would be: a turn the checker cannot read holds nothing.
+func (t *Turns) Put(key string, value []byte, deleted bool) bool {
+	repository, err := delivery.ParseTurnsKey(key)
+	if err != nil {
+		return false
+	}
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	if t.byRepo == nil {
+		t.byRepo = map[string]delivery.Turn{}
+	}
+	cur, had := t.byRepo[repository]
+	if !deleted {
+		if turn, err := delivery.DecodeTurn(value); err == nil {
+			t.byRepo[repository] = turn
+			return !had || !delivery.SameTurn(cur, turn)
+		}
+	}
+	delete(t.byRepo, repository)
+	return had
+}
+
+// Holding names the first of the repositories (by name) a turn holds off the check of the heads, and the delivery that
+// waits first in it; false when none does.
+func (t *Turns) Holding(repositories []string, heads string) (string, delivery.TurnWait, bool) {
+	if t == nil {
+		return "", delivery.TurnWait{}, false
+	}
+	sorted := make([]string, 0, len(repositories))
+	for _, r := range repositories {
+		sorted = append(sorted, strings.ToLower(r))
+	}
+	sort.Strings(sorted)
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	for _, r := range sorted {
+		turn, ok := t.byRepo[r]
+		if !ok || !delivery.TurnHolds(turn, heads) {
+			continue
+		}
+		for _, w := range turn.Waiting {
+			if w.Heads != heads {
+				return r, w, true
+			}
+		}
+	}
+	return "", delivery.TurnWait{}, false
+}
+
+// All is every turn held now, by repository (a copy).
+func (t *Turns) All() map[string]delivery.Turn {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	out := make(map[string]delivery.Turn, len(t.byRepo))
+	for r, turn := range t.byRepo {
+		out[r] = turn
+	}
+	return out
+}

modules/mesh-delivery-checker/manifest_test.go

@@ -38,6 +38,11 @@ type stream struct {
 }
 
 type manifest struct {
+	Claims []struct {
+		Name   string   `json:"name"`
+		Scope  string   `json:"scope"`
+		Serves []string `json:"serves"`
+	} `json:"claims"`
 	Streams  []stream `json:"streams"`
 	Tools    []string `json:"tools"`
 	Module   string   `json:"module"`
@@ -93,11 +98,11 @@ func TestManifestDeclarations(t *testing.T) { // 1678/AC1
 		t.Errorf("module = %q", m.Module)
 	}
 	// delivery.CheckerKeptHistory, CheckerOwedHistory, PreviewsHistory, CheckerVerdictsHistory; the names follow the SDK's buckets.
-	if want := []state{{Name: "kept", History: 1}, {Name: "owed", History: 5}, {Name: "previews", History: 5}, {Name: "tries", History: 1}, {Name: "verdicts", History: 5}}; !reflect.DeepEqual(m.State, want) {
+	if want := []state{{Name: "asks", History: 1}, {Name: "hearing", History: 1}, {Name: "kept", History: 1}, {Name: "owed", History: 5}, {Name: "previews", History: 5}, {Name: "tries", History: 1}, {Name: "verdicts", History: 5}}; !reflect.DeepEqual(m.State, want) {
 		t.Errorf("state = %+v, want %+v", m.State, want)
 	}
-	if want := []string{"mesh-build-go.steps", "mesh-build-go.toolchains", "mesh-build-node.steps", "mesh-build-node.toolchains", "mesh-controller.assignments",
-		"mesh-delivery-assigner.compositions", "mesh-delivery-builder.builds", "mesh-delivery-gate.source", "mesh-delivery-indexer.candidates",
+	if want := []string{"mesh-build-go.steps", "mesh-build-go.toolchains", "mesh-build-node.steps", "mesh-build-node.toolchains",
+		"mesh-delivery-assigner.compositions", "mesh-delivery-assigner.placement", "mesh-delivery-builder.builds", "mesh-delivery-gate.source", "mesh-delivery-gate.turns", "mesh-delivery-indexer.candidates",
 		"mesh-delivery-indexer.manifests", "mesh-delivery-indexer.modules", "mesh-delivery-watchman.presence", "node-engine.have"}; !reflect.DeepEqual(sorted(m.Reads), want) {
 		t.Errorf("reads = %v, want %v", m.Reads, want)
 	}
@@ -124,11 +129,17 @@ func TestManifestDeclarations(t *testing.T) { // 1678/AC1
 		t.Errorf("streams = %+v, want %+v", m.Streams, want)
 	}
 	// The read tools (issue 1686) are served by the tools bundle, not by the checker's process.
-	// The try's two tools (ADR 0501 §5) beside them: mesh-controller's try calls them.
-	if want := []string{"checker_kept", "checker_previews", "checker_pull", "checker_status", "checker_try", "checker_try_read", "checker_verdicts"}; !reflect.DeepEqual(sorted(m.Tools), want) {
+	// The try's tools (ADR 0501 §5; the end by hand, issue 734) beside them: mesh-controller's try calls them. A lost check
+	// is asked again by hand (checker_ask_again).
+	if want := []string{"checker_ask_again", "checker_kept", "checker_previews", "checker_pull", "checker_status", "checker_try", "checker_try_end", "checker_try_read", "checker_verdicts"}; !reflect.DeepEqual(sorted(m.Tools), want) {
 		t.Errorf("tools = %v, want %v", m.Tools, want)
 	}
-	for _, k := range []string{"logs", "emits", "claims", "provides", "requires", "defines-seats", "seat", "seats", "bus", "config"} {
+	// The try is the checker's own seat's verbs (ADR 0547 §10, issue 774), served beside the tools by the same code.
+	if len(m.Claims) != 1 || m.Claims[0].Name != "mesh-delivery-checker" || m.Claims[0].Scope != "mesh" ||
+		!reflect.DeepEqual(m.Claims[0].Serves, []string{"try", "try-read", "try-end"}) {
+		t.Errorf("claims = %+v, want the mesh seat mesh-delivery-checker serving try, try-read and try-end", m.Claims)
+	}
+	for _, k := range []string{"logs", "emits", "provides", "requires", "defines-seats", "seat", "seats", "bus", "config"} {
 		if _, ok := top[k]; ok {
 			t.Errorf("the manifest declares %q: the checker has none", k)
 		}

modules/mesh-delivery-checker/module.json

@@ -2,6 +2,17 @@
   "module": "mesh-delivery-checker",
   "version": "1",
   "slug": "checker",
+  "claims": [
+    {
+      "name": "mesh-delivery-checker",
+      "scope": "mesh",
+      "serves": [
+        "try",
+        "try-read",
+        "try-end"
+      ]
+    }
+  ],
   "consumes": [
     "mesh-build-go.toolchain.reported",
     "mesh-build-node.toolchain.reported"
@@ -10,6 +21,8 @@
     { "name": "checks", "events": ["preview.**", "owed.**"] }
   ],
   "state": [
+    { "name": "asks", "history": 1 },
+    { "name": "hearing", "history": 1 },
     { "name": "kept", "history": 1 },
     { "name": "owed", "history": 5 },
     { "name": "previews", "history": 5 },
@@ -21,10 +34,11 @@
     "mesh-build-go.toolchains",
     "mesh-build-node.steps",
     "mesh-build-node.toolchains",
-    "mesh-controller.assignments",
     "mesh-delivery-assigner.compositions",
+    "mesh-delivery-assigner.placement",
     "mesh-delivery-builder.builds",
     "mesh-delivery-gate.source",
+    "mesh-delivery-gate.turns",
     "mesh-delivery-indexer.candidates",
     "mesh-delivery-indexer.manifests",
     "mesh-delivery-indexer.modules",
@@ -36,11 +50,13 @@
     "node-build-node"
   ],
   "tools": [
+    "checker_ask_again",
     "checker_kept",
     "checker_previews",
     "checker_pull",
     "checker_status",
     "checker_try",
+    "checker_try_end",
     "checker_try_read",
     "checker_verdicts"
   ],

modules/mesh-delivery-forge-bridge/cmd/mesh-delivery-forge-bridge/integration_test.go

@@ -21,6 +21,7 @@ import (
 	"github.com/nats-io/nats.go/jetstream"
 
 	"git.novox.be/novox/mesh-sdk/go/delivery"
+	"git.novox.be/novox/mesh-sdk/go/process"
 )
 
 // busConf is the shape of the composed accounts file (mesh-controller internal/broker): one account with JetStream,
@@ -71,11 +72,17 @@ accounts {
             "mesh.mod.gitea.tool.gitea_open_pulls"
             "mesh.mod.gitea.tool.gitea_open_pulls.*"
             "$JS.API.CONSUMER.CREATE.KV_mesh-delivery-forge-bridge_performed.>"
+            "$JS.API.CONSUMER.CREATE.KV_mesh-delivery-forge-bridge_inputs.>"
             "$JS.API.CONSUMER.DELETE.KV_mesh-delivery-forge-bridge_performed.>"
+            "$JS.API.CONSUMER.DELETE.KV_mesh-delivery-forge-bridge_inputs.>"
             "$JS.API.DIRECT.GET.KV_mesh-delivery-forge-bridge_performed.>"
+            "$JS.API.DIRECT.GET.KV_mesh-delivery-forge-bridge_inputs.>"
             "$JS.API.STREAM.INFO.KV_mesh-delivery-forge-bridge_performed"
+            "$JS.API.STREAM.INFO.KV_mesh-delivery-forge-bridge_inputs"
             "$JS.FC.KV_mesh-delivery-forge-bridge_performed.>"
+            "$JS.FC.KV_mesh-delivery-forge-bridge_inputs.>"
             "$KV.mesh-delivery-forge-bridge_performed.>"
+            "$KV.mesh-delivery-forge-bridge_inputs.>"
             "$JS.API.CONSUMER.CREATE.KV_mesh-delivery-gate_merges.>"
             "$JS.API.CONSUMER.DELETE.KV_mesh-delivery-gate_merges.>"
             "$JS.API.DIRECT.GET.KV_mesh-delivery-gate_merges.>"
@@ -218,7 +225,7 @@ func startBed(t *testing.T, openReply string, prepare func(ctx context.Context,
 	}
 	// Its other state bucket, and the gate's buckets the bridge reads, made by the controller from the gate's manifest
 	// (mesh-sdk go/delivery MergesBucket, OwedBucket with their histories).
-	for name, history := range map[string]uint8{performedBucket: 1, delivery.MergesBucket: delivery.MergesHistory, delivery.OwedBucket: delivery.OwedHistory} {
+	for name, history := range map[string]uint8{performedBucket: 1, inputsBucket: 1, delivery.MergesBucket: delivery.MergesHistory, delivery.OwedBucket: delivery.OwedHistory} {
 		if _, err := js.CreateKeyValue(ctx, jetstream.KeyValueConfig{Bucket: name, History: history}); err != nil {
 			t.Fatal(err)
 		}
@@ -271,7 +278,7 @@ func startBed(t *testing.T, openReply string, prepare func(ctx context.Context,
 	}
 
 	broker := filepath.Join(t.TempDir(), "broker")
-	cred, _ := json.Marshal(credential{URL: srv.ClientURL(), Node: "n1", Module: "mesh-delivery-forge-bridge", User: "n1.mesh-delivery-forge-bridge", Password: "pw"})
+	cred, _ := json.Marshal(process.Account{URL: srv.ClientURL(), Node: "n1", Module: "mesh-delivery-forge-bridge", User: "n1.mesh-delivery-forge-bridge", Password: "pw"})
 	if err := os.WriteFile(broker, cred, 0o600); err != nil {
 		t.Fatal(err)
 	}

modules/mesh-delivery-forge-bridge/cmd/mesh-delivery-forge-bridge/kept.go

@@ -0,0 +1,81 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"log"
+	"regexp"
+	"sync"
+	"time"
+
+	"github.com/nats-io/nats.go/jetstream"
+
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+
+	"mesh-delivery-forge-bridge/internal/bridge"
+)
+
+// inputsBucket is the module's state bucket inputs (manifest state entry inputs): what the bridge read of a module
+// directory, its manifest and lock-file hashes, by the directory's git tree hash, so a merge reads the forge only for the
+// directories it changed (issue 1126; internal/bridge kept.go). A tree hash names its bytes, so a value is never stale;
+// a merge adds a value only for each directory it changed (a few kilobytes each).
+const inputsBucket = delivery.ForgeBridgeModule + "_inputs"
+
+// keptTimeout bounds one read or write of the bucket: the bucket is a saving, never a reason to fail a merge.
+const keptTimeout = 2 * time.Second
+
+var treeHash = regexp.MustCompile(`^[0-9a-f]{40}$|^[0-9a-f]{64}$`)
+
+// kept is the bridge's Kept: in memory always, and in the bucket inputs when it is on the bus, so the first merge after a
+// start reads only what changed too. A value the bucket cannot give or take is read from the forge, and said.
+type kept struct {
+	kv     jetstream.KeyValue // nil when the bucket is not on the bus
+	logger *log.Logger
+	mu     sync.Mutex
+	mem    map[string]bridge.Inputs
+}
+
+func newKept(kv jetstream.KeyValue, logger *log.Logger) *kept {
+	return &kept{kv: kv, logger: logger, mem: map[string]bridge.Inputs{}}
+}
+
+func (k *kept) Get(tree string) (bridge.Inputs, bool) {
+	k.mu.Lock()
+	in, ok := k.mem[tree]
+	k.mu.Unlock()
+	if ok || k.kv == nil || !treeHash.MatchString(tree) {
+		return in, ok
+	}
+	ctx, cancel := context.WithTimeout(context.Background(), keptTimeout)
+	defer cancel()
+	e, err := k.kv.Get(ctx, tree)
+	if err != nil {
+		return bridge.Inputs{}, false // not kept (or not readable): read from the forge
+	}
+	if err := json.Unmarshal(e.Value(), &in); err != nil || in.Manifest == "" {
+		k.logger.Printf("%s.%s cannot be read, so its directory is read from the forge: %v", inputsBucket, tree, err)
+		return bridge.Inputs{}, false
+	}
+	k.mu.Lock()
+	k.mem[tree] = in
+	k.mu.Unlock()
+	return in, true
+}
+
+func (k *kept) Put(tree string, in bridge.Inputs) {
+	k.mu.Lock()
+	k.mem[tree] = in
+	k.mu.Unlock()
+	if k.kv == nil || !treeHash.MatchString(tree) {
+		return
+	}
+	data, err := json.Marshal(in)
+	if err != nil {
+		return
+	}
+	ctx, cancel := context.WithTimeout(context.Background(), keptTimeout)
+	defer cancel()
+	if _, err := k.kv.Put(ctx, tree, data); err != nil {
+		k.logger.Printf("%s.%s is not kept, so the next merge reads its directory from the forge again: %v", inputsBucket, tree, err)
+	}
+}

modules/mesh-delivery-forge-bridge/cmd/mesh-delivery-forge-bridge/main.go

@@ -6,18 +6,12 @@ package main
 
 import (
 	"context"
-	"crypto/sha256"
-	"crypto/tls"
-	"crypto/x509"
-	"encoding/hex"
-	"encoding/json"
 	"errors"
 	"fmt"
 	"io"
 	"log"
 	"os"
 	"os/signal"
-	"strings"
 	"sync"
 	"syscall"
 	"time"
@@ -39,7 +33,7 @@ const eventsStream = "EVENTS"
 // The bridge's own stream FORGE takes `mesh.stream.<module>.event.<event>` (mesh-control internal/broker
 // modstreams.go ModuleStreamSubject).
 func forgeSubject(event string) string {
-	return "mesh.stream." + delivery.ForgeBridgeModule + ".event." + event
+	return process.ModuleStreamSubject(delivery.ForgeBridgeModule, event)
 }
 
 func main() {
@@ -51,50 +45,6 @@ func main() {
 	}
 }
 
-// credential is the broker file the controller issues to the module: JSON of the bus address, the certificate
-// fingerprint to pin, the principal and its password (as the watchman reads it; issue 1242 moves this into the SDK).
-type credential struct {
-	URL         string `json:"url"`
-	Fingerprint string `json:"fingerprint"`
-	Node        string `json:"node"`
-	Module      string `json:"module"`
-	User        string `json:"user"`
-	Password    string `json:"password"`
-}
-
-func readCredential(path string) (credential, error) {
-	raw, err := os.ReadFile(path)
-	if err != nil {
-		return credential{}, err
-	}
-	var c credential
-	if err := json.Unmarshal(raw, &c); err != nil {
-		return credential{}, fmt.Errorf("the broker credential is not one: %w", err)
-	}
-	if c.URL == "" || c.User == "" {
-		return credential{}, errors.New("the broker credential names no bus address or user")
-	}
-	return c, nil
-}
-
-// pinned accepts exactly the certificate with this SHA-256 and no other.
-func pinned(want string) *tls.Config {
-	return &tls.Config{
-		InsecureSkipVerify: true, //nolint:gosec // replaced by the pin below, which is stricter
-		MinVersion:         tls.VersionTLS12,
-		VerifyPeerCertificate: func(rawCerts [][]byte, _ [][]*x509.Certificate) error {
-			if len(rawCerts) == 0 {
-				return errors.New("the bus presented no certificate")
-			}
-			sum := sha256.Sum256(rawCerts[0])
-			if got := "sha256:" + hex.EncodeToString(sum[:]); got != want {
-				return fmt.Errorf("the bus presented a certificate this mesh does not know (%.23s…)", got)
-			}
-			return nil
-		},
-	}
-}
-
 // delivered is the part of a JetStream message the bridge uses.
 type delivered interface {
 	Subject() string
@@ -117,8 +67,8 @@ type publisher interface {
 // handle turns one event into its message on FORGE and acknowledges it. An event it cannot read is terminated, never
 // redelivered, and the log names its subject and why. A message it could not write stays unacknowledged: the server
 // delivers it again (the server's ack wait is the only clock).
-func handle(ctx context.Context, m delivered, pub publisher, trees bridge.Trees, files bridge.Files, logger *log.Logger) {
-	msg, err := bridge.Convert(m.Subject(), m.Data(), trees, files)
+func handle(ctx context.Context, m delivered, pub publisher, trees bridge.Trees, files bridge.Files, kept bridge.Kept, logger *log.Logger) {
+	msg, err := bridge.ConvertKept(m.Subject(), m.Data(), trees, files, kept)
 	switch {
 	case errors.Is(err, bridge.ErrRetry):
 		logger.Printf("%v; heard again in %s", err, retryDelay)
@@ -146,46 +96,32 @@ func handle(ctx context.Context, m delivered, pub publisher, trees bridge.Trees,
 		logger.Printf("%s: %s could not be written on FORGE, left for redelivery: %v", m.Subject(), msg.Event, err)
 		return
 	}
+	if msg.Said != "" {
+		logger.Printf("%s: %s", m.Subject(), msg.Said)
+	}
 	_ = m.Ack()
 }
 
 // run is the program: it returns when ctx ends or the bus cannot be used.
 func run(ctx context.Context, getenv func(string) string, logOut io.Writer) error {
 	logger := log.New(logOut, "mesh-delivery-forge-bridge: ", log.LstdFlags)
-	path := strings.TrimSpace(getenv("MESH_BROKER_FILE"))
-	if path == "" {
-		return errors.New("MESH_BROKER_FILE is not set, so there is no credential to hear the bus with")
-	}
-	cred, err := readCredential(path)
+	cred, err := process.ReadBrokerAccount(getenv)
 	if err != nil {
 		return err
 	}
 	again := make(chan struct{}, 1)
-	opts := []nats.Option{
-		nats.Name(cred.Node + "." + cred.Module),
-		nats.UserInfo(cred.User, cred.Password),
-		nats.CustomInboxPrefix("_INBOX." + cred.User),
-		nats.MaxReconnects(-1),
-		nats.RetryOnFailedConnect(true),
+	conn, js, err := cred.Dial(
 		nats.ReconnectHandler(func(*nats.Conn) {
 			select {
 			case again <- struct{}{}:
 			default:
 			}
 		}),
-	}
-	if strings.TrimSpace(cred.Fingerprint) != "" {
-		opts = append(opts, nats.Secure(pinned(cred.Fingerprint)))
-	}
-	conn, err := nats.Connect(cred.URL, opts...)
-	if err != nil {
-		return fmt.Errorf("connecting to the bus: %w", err)
-	}
-	defer conn.Close()
-	js, err := jetstream.New(conn)
+	)
 	if err != nil {
 		return err
 	}
+	defer conn.Close()
 	// What the forge holds open, said before any event is heard, and again at each reconnect (ADR 0429 §13).
 	call := callerOn(conn, cred.User)
 	// No forge event is heard while the open pull requests are read and said (ADR 0443 §5): events and syncs take turns.
@@ -227,20 +163,21 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 		return err
 	}
 	go onReconnect(ctx, again, said, logger)
-	cons, err := js.Consumer(ctx, eventsStream, cred.Node+"_"+cred.Module)
+	// What a merge read of each module directory, by its tree (issue 1126): a merge reads only the directories it changed.
+	inputs := newKept(process.OptionalBucket(ctx, js, inputsBucket, "a merge's module directories are kept in memory only, so the first merge after a start reads every one", logger.Printf), logger)
+	cons, err := cred.EventConsumer(ctx, js, eventsStream)
 	if err != nil {
 		// Essential: the forge's events are what the bridge carries.
 		return fmt.Errorf("the consumer %s_%s on %s cannot be read (%v): the bridge hears no forge event without it, so it stops; where the bus refused it or did not answer, this module's consumes (made by the controller with its grant) have not reached the bus yet", cred.Node, cred.Module, eventsStream, err)
 	}
-	cc, err := cons.Consume(func(m jetstream.Msg) {
+	cc, err := process.HearEvents(cons, func(m jetstream.Msg) {
 		hear(&turn, func() {
 			// Bounded: the turn is held, and no sync or other event goes on without it.
 			hctx, cancel := context.WithTimeout(ctx, syncDeadline)
 			defer cancel()
-			handle(hctx, m, rec, treesVia(hctx, call), filesVia(hctx, call), logger)
+			handle(hctx, m, rec, treesVia(hctx, call), filesVia(hctx, call), inputs, logger)
 		})
-	},
-		jetstream.ConsumeErrHandler(func(_ jetstream.ConsumeContext, err error) { logger.Printf("hearing the bus: %v", err) }))
+	}, logger.Printf)
 	if err != nil {
 		return err
 	}

modules/mesh-delivery-forge-bridge/cmd/mesh-delivery-forge-bridge/main_test.go

@@ -81,7 +81,7 @@ func TestReadableEventIsWrittenOnForgeAndAcked(t *testing.T) { // 1235/AC2 (unit
 	})
 	var logs bytes.Buffer
 	m, pub := &fakeMsg{subject: "mesh.mod.gitea.event.pull.updated", data: body(nil)}, &fakePub{}
-	handle(context.Background(), m, pub, nil, someFiles, log.New(&logs, "", 0))
+	handle(context.Background(), m, pub, nil, someFiles, nil, log.New(&logs, "", 0))
 	if len(pub.subjects) != 1 || pub.subjects[0] != "mesh.stream.mesh-delivery-forge-bridge.event.forge.novox.mesh-delivery.pull" {
 		t.Fatalf("published on %v", pub.subjects)
 	}
@@ -97,7 +97,7 @@ func TestReadableEventIsWrittenOnForgeAndAcked(t *testing.T) { // 1235/AC2 (unit
 func TestUnreadableEventIsTerminatedAndLogged(t *testing.T) { // 1235/AC5
 	var logs bytes.Buffer
 	m, pub := &fakeMsg{subject: "mesh.mod.gitea.event.pull.updated", data: body(map[string]any{"head_sha": "short"})}, &fakePub{}
-	handle(context.Background(), m, pub, nil, someFiles, log.New(&logs, "", 0))
+	handle(context.Background(), m, pub, nil, someFiles, nil, log.New(&logs, "", 0))
 	if len(pub.subjects) != 0 {
 		t.Errorf("a message was written: %v", pub.subjects)
 	}
@@ -112,7 +112,7 @@ func TestUnreadableEventIsTerminatedAndLogged(t *testing.T) { // 1235/AC5
 func TestUnwrittenMessageIsNotAcked(t *testing.T) { // 1235 (a failed write is redelivered by the server, not retried here)
 	var logs bytes.Buffer
 	m, pub := &fakeMsg{subject: "mesh.mod.gitea.event.pull.updated", data: body(nil)}, &fakePub{err: errors.New("no stream")}
-	handle(context.Background(), m, pub, nil, someFiles, log.New(&logs, "", 0))
+	handle(context.Background(), m, pub, nil, someFiles, nil, log.New(&logs, "", 0))
 	if m.acked != 0 || m.termd != 0 {
 		t.Errorf("acked %d terminated %d, want neither", m.acked, m.termd)
 	}
@@ -134,7 +134,7 @@ func TestTreesRefusedLeavesTheEventForTenSecondsAndLogs(t *testing.T) { // 1236/
 	call := func(context.Context, string, any) (json.RawMessage, error) {
 		return nil, errors.New("the tree listing of novox/mesh-delivery was cut")
 	}
-	handle(context.Background(), m, pub, treesVia(context.Background(), call), filesVia(context.Background(), call), log.New(&logs, "", 0))
+	handle(context.Background(), m, pub, treesVia(context.Background(), call), filesVia(context.Background(), call), nil, log.New(&logs, "", 0))
 	if len(pub.subjects) != 0 {
 		t.Errorf("a message was written: %v", pub.subjects)
 	}
@@ -163,7 +163,7 @@ func TestMergeCallsTheToolOnceAndWritesTheMergedMessage(t *testing.T) { // 1236/
 		}
 		return json.RawMessage(`{"root":"r0","trees":{"":"t0","modules/a":"t1"}}`), nil
 	}
-	handle(context.Background(), m, pub, treesVia(context.Background(), call), filesVia(context.Background(), call), log.New(&logs, "", 0))
+	handle(context.Background(), m, pub, treesVia(context.Background(), call), filesVia(context.Background(), call), nil, log.New(&logs, "", 0))
 	if len(keys) == 0 || keys[0] != "gitea.gitea_commit_trees" || slices.Index(keys[1:], "gitea.gitea_commit_trees") >= 0 {
 		t.Fatalf("calls %v, want the trees once and first", keys)
 	}

modules/mesh-delivery-forge-bridge/go.mod

@@ -3,7 +3,7 @@ module mesh-delivery-forge-bridge
 go 1.26.0
 
 require (
-	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261025211220-e0d1de047585
+	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261028174713-38dbe1d3a388
 	github.com/nats-io/nats-server/v2 v2.11.17
 	github.com/nats-io/nats.go v1.54.0
 )

modules/mesh-delivery-forge-bridge/go.sum

@@ -1,7 +1,5 @@
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261022190740-104533e8c0c9 h1:Ufmd2cYEXICQ817IGflccP9bexABE4WhIO49HPbaoSo=
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261022190740-104533e8c0c9/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261025211220-e0d1de047585 h1:7QoFH5qjXRpx5M4uPdYsVJ5qKl2082gq8n0lFxhoNIg=
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261025211220-e0d1de047585/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261028174713-38dbe1d3a388 h1:ycu/sNieTdLpD3bzhZOCXdzcoqXUOxPRmqWV019REpo=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261028174713-38dbe1d3a388/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op h1:Z/MZK75wC/NSrkgqeNIa7jexam9uWzhLmFTSCPI/kn0=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op/go.mod h1:FQyySiasQQM8735Ddel3MRojmy4dA1IqCeyJ5jmPMbI=
 github.com/google/go-tpm v0.9.8 h1:slArAR9Ft+1ybZu0lBwpSmpwhRXaa85hWtMinMyRAWo=

modules/mesh-delivery-forge-bridge/internal/bridge/bridge.go

@@ -7,6 +7,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"maps"
 	"path"
 	"regexp"
 	"slices"
@@ -53,6 +54,8 @@ var LockFiles = []string{"go.sum", "package-lock.json"}
 type Message struct {
 	Event string
 	Data  []byte
+	// Said is what the bridge did that the log says, beside writing the message; empty for none.
+	Said string
 }
 
 // The subjects of the forge module's events the bridge writes pull messages for (mesh-catalog modules/gitea,
@@ -77,6 +80,10 @@ type pull struct {
 	ModuleDirsSaid bool     `json:"module_dirs_said"`
 	Base           string   `json:"base"`
 	MergeSHA       string   `json:"merge_commit_sha"`
+	// Paths are the files the pull request changes (a removed or renamed one included), PathsTruncated says the forge
+	// cut the list; nil when the forge did not say them.
+	Paths          *[]string `json:"paths"`
+	PathsTruncated bool      `json:"paths_truncated"`
 }
 
 func unreadable(subject, why string, args ...any) error {
@@ -88,6 +95,12 @@ func unreadable(subject, why string, args ...any) error {
 // the trunk asks trees once and becomes a merged message; a merge into any other branch is a closed pull message, as the
 // pull request left its group. A forge that cannot say is ErrRetry; a merge with no module.json is ErrNoModules.
 func Convert(subject string, data []byte, trees Trees, files Files) (Message, error) {
+	return ConvertKept(subject, data, trees, files, nil)
+}
+
+// ConvertKept is Convert; with kept, a merge reads the forge only for the module directories whose tree hash kept
+// does not hold, and keeps what it read (kept.go).
+func ConvertKept(subject string, data []byte, trees Trees, files Files, kept Kept) (Message, error) {
 	var action string
 	switch subject {
 	case UpdatedSubject:
@@ -114,7 +127,16 @@ func Convert(subject string, data []byte, trees Trees, files Files) (Message, er
 		return Message{}, unreadable(subject, "no branch")
 	}
 	if subject == MergedSubject && p.Base == Trunk {
-		return merged(subject, p, trees, files)
+		return merged(subject, p, trees, files, kept)
+	}
+	said := ""
+	if action == delivery.PullUpdated && p.Base != "" && p.Base != Trunk {
+		// The checker judges pull requests into main only, and source.main names main's head only (novox/hq ADR 0484 §11): a
+		// pull request into another base is no candidate, as it is none at the start (OpenPulls) and at its merge. It is
+		// written closed, so a candidate an older head made is taken out, and said (issue 1422).
+		action = delivery.PullClosed
+		said = fmt.Sprintf("%s/%s#%d at %s is into %s, not %s: written closed, so it is no candidate; the checker judges pull requests into %s only (novox/hq ADR 0484 §11)",
+			p.Owner, p.Repo, p.Number, p.HeadSHA[:12], p.Base, Trunk, Trunk)
 	}
 	f := delivery.Forge{Kind: delivery.ForgePull, Repository: p.Owner + "/" + p.Repo, Branch: p.Head, Number: p.Number,
 		Head: p.HeadSHA, Action: action}
@@ -134,7 +156,7 @@ func Convert(subject string, data []byte, trees Trees, files Files) (Message, er
 	if err != nil {
 		return Message{}, unreadable(subject, "%v", err)
 	}
-	return Message{Event: event, Data: body}, nil
+	return Message{Event: event, Data: body, Said: said}, nil
 }
 
 // MaxReadsInFlight is how many files of the forge inputsOf asks for at once. A merge into a repository of many
@@ -147,6 +169,7 @@ const MaxReadsInFlight = 8
 type read struct {
 	dir, path string
 	manifest  bool
+	asked     bool
 	raw       []byte
 	err       error
 }
@@ -160,6 +183,14 @@ type read struct {
 // order the calls finish in, and the error is that of the first failing file in the order of dirs and LockFiles. After
 // a failure no further file is asked for, and inputsOf returns only when every call it started has returned.
 func inputsOf(owner, repo, ref string, dirs []string, files Files) (manifests map[string]string, locks map[string]map[string]string, err error) {
+	manifests, locks, _, err = inputsRead(owner, repo, ref, dirs, files)
+	return manifests, locks, err
+}
+
+// inputsRead is inputsOf, and also answers, on a failure too, the directories whose manifest and lock files were all
+// read, with their manifests and lock hashes: a merge keeps them by their tree, so its next try reads only the rest
+// (issue 1126).
+func inputsRead(owner, repo, ref string, dirs []string, files Files) (manifests map[string]string, locks map[string]map[string]string, whole []string, err error) {
 	at := func(dir, name string) string {
 		if dir == "" {
 			return name
@@ -188,6 +219,7 @@ func inputsOf(owner, repo, ref string, dirs []string, files Files) (manifests ma
 			<-slots
 			break
 		}
+		r.asked = true
 		wg.Add(1)
 		go func(r *read) {
 			defer func() { <-slots; wg.Done() }()
@@ -202,10 +234,16 @@ func inputsOf(owner, repo, ref string, dirs []string, files Files) (manifests ma
 	wg.Wait()
 	manifests = map[string]string{}
 	locks = map[string]map[string]string{}
+	broken := map[string]bool{} // a directory with a file not read (failed, or never asked after a failure)
 	for _, r := range reads {
 		switch {
 		case r.err != nil && (r.manifest || !errors.Is(r.err, ErrNotFound)):
-			return nil, nil, fmt.Errorf("%s: %w", r.path, r.err)
+			broken[r.dir] = true
+			if err == nil {
+				err = fmt.Errorf("%s: %w", r.path, r.err)
+			}
+		case r.err == nil && r.raw == nil && !r.asked:
+			broken[r.dir] = true
 		case r.err != nil: // a lock file the forge does not have
 		case r.manifest:
 			manifests[r.dir] = string(r.raw)
@@ -217,17 +255,29 @@ func inputsOf(owner, repo, ref string, dirs []string, files Files) (manifests ma
 			locks[r.dir][path.Base(r.path)] = hex.EncodeToString(sum[:])
 		}
 	}
+	for _, dir := range dirs {
+		if !broken[dir] {
+			whole = append(whole, dir)
+		}
+	}
+	if err != nil {
+		for dir := range broken {
+			delete(manifests, dir)
+			delete(locks, dir)
+		}
+		return manifests, locks, whole, err
+	}
 	if len(manifests) == 0 {
 		manifests = nil
 	}
 	if len(locks) == 0 {
 		locks = nil
 	}
-	return manifests, locks, nil
+	return manifests, locks, whole, nil
 }
 
 // merged is the merged message of a merge into the trunk: the trees of the merge commit, asked once.
-func merged(subject string, p pull, trees Trees, files Files) (Message, error) {
+func merged(subject string, p pull, trees Trees, files Files, kept Kept) (Message, error) {
 	if !sha40.MatchString(p.MergeSHA) {
 		return Message{}, unreadable(subject, "the merge commit %q is not 40 hex digits", p.MergeSHA)
 	}
@@ -244,16 +294,28 @@ func merged(subject string, p pull, trees Trees, files Files) (Message, error) {
 		names = append(names, dir)
 	}
 	slices.Sort(names)
-	manifests, locks, err := inputsOf(p.Owner, p.Repo, p.MergeSHA, names, files)
+	manifests, locks, toRead := keptInputs(names, dirs, kept)
+	read, readLocks, whole, err := inputsRead(p.Owner, p.Repo, p.MergeSHA, toRead, files)
 	if err != nil {
-		return Message{}, fmt.Errorf("%w: %s: the manifests of %s at the merge commit %s: %v", ErrRetry, subject, repository, p.MergeSHA, err)
+		keep(whole, dirs, read, readLocks, kept) // what was read whole is not asked again at the next try
+		return Message{}, fmt.Errorf("%w: %s: the manifests of %s at the merge commit %s (%d of %d module directories read from the forge, the others kept by their tree): %v", ErrRetry, subject, repository, p.MergeSHA, len(toRead), len(names), err)
+	}
+	keep(toRead, dirs, read, readLocks, kept)
+	maps.Copy(manifests, read)
+	maps.Copy(locks, readLocks)
+	if len(manifests) == 0 {
+		manifests = nil
+	}
+	if len(locks) == 0 {
+		locks = nil
 	}
 	event, err := delivery.ForgeEvent(repository, delivery.ForgeMerged)
 	if err != nil {
 		return Message{}, unreadable(subject, "%v", err)
 	}
-	body, err := delivery.EncodeForge(delivery.Forge{Kind: delivery.ForgeMerged, Repository: repository, Branch: p.Head, Number: p.Number,
-		Head: p.HeadSHA, Merge: p.MergeSHA, Root: root, Trees: dirs, Manifests: manifests, Locks: locks})
+	f := delivery.Forge{Kind: delivery.ForgeMerged, Repository: repository, Branch: p.Head, Number: p.Number,
+		Head: p.HeadSHA, Merge: p.MergeSHA, Root: root, Trees: dirs, Manifests: manifests, Locks: locks}
+	body, err := delivery.EncodeForge(f)
 	if err != nil {
 		return Message{}, unreadable(subject, "%v", err)
 	}