Merge pull request 'Keep the controller lease through a stalled renewal until its TTL passes (hq issue 477)' (#331) from fix-477-lease-survives-stall into main

A bus stall of a few seconds made a renewal time out, and the controller
called that a lost lease, exited and raised the urgent lease-lost alert,
though no other controller could take a key that still lived. Now only
another holder seen, or the key's TTL passed unrenewed, loses the lease;
new acts stop at half the TTL unrenewed and resume on the next renewal
(novox/hq issue 477).

cmd/mesh-builder/main.go

@@ -319,7 +319,7 @@ func answer(ctx context.Context, publisher builder.Publisher, on, workspace stri
 		// at build time has no reuse key anyway, so nothing is lost by refusing it here.
 		if isRegistry && len(spec.Builds) > 0 {
 			spec.BuildWith = &builder.CheckBuilding{Publish: publisher, Scratch: registryHere, Held: request.Held,
-				Seats: request.Seats}
+				Seats: request.Seats, Named: namedOf(request.Check.Named)}
 		}
 		var v builder.CheckVerdict
 		v, err = builder.Check(building, builder.Command, spec, workspace, registry, forgeFrom(), say)
@@ -332,6 +332,12 @@ func answer(ctx context.Context, publisher builder.Publisher, on, workspace stri
 				result.Check.Members = append(result.Check.Members, link.CheckedMember{Owner: m.Owner, Repo: m.Repo,
 					Commit: m.Head, Trunk: m.Trunk})
 			}
+			// A branch tried before its pull request reads its outcome from this log, whole (novox/hq issue 686).
+			if request.Check.Try {
+				if line, err := json.Marshal(triedOf(v)); err == nil {
+					say(link.StepTried, string(line))
+				}
+			}
 		}
 	} else if err == nil {
 		// The package-registry credential is a build input, so it is resolved before the clone: a
@@ -346,15 +352,7 @@ func answer(ctx context.Context, publisher builder.Publisher, on, workspace stri
 				reuse.Pulls = append(reuse.Pulls, builder.PullRef{Owner: p.Owner, Repo: p.Repo, Number: p.Number})
 			}
 			// Only what a verdict names is taken (ADR 0350 §2).
-			for _, b := range request.Reuse.Builds {
+			reuse.Named = namedOf(request.Reuse.Builds)
-				named := builder.NamedBuild{Pull: builder.PullRef{Owner: b.Pull.Owner, Repo: b.Pull.Repo,
-					Number: b.Pull.Number}, Check: b.Check, Module: b.Built.Module, Key: b.Built.Key,
-					Digests: map[string]string{}}
-				for _, m := range b.Built.Made {
-					named.Digests[m.Name] = builder.DigestOf(m.Reference)
-				}
-				reuse.Named = append(reuse.Named, named)
-			}
 			built, err = builder.BuildReusing(building, builder.Labelled(builder.Command, request.ID), publisher, reuse,
 				request.Repository, request.Path, request.Ref, workspace, request.Held, npmrc,
 				forgeFrom(), say, request.Seats)
@@ -457,7 +455,8 @@ func checkSpecOf(request link.BuildRequest) builder.CheckSpec {
 	spec := builder.CheckSpec{ID: request.ID, Repository: request.Repository, Ref: request.Ref,
 		Owner: c.Owner, Repo: c.Repo, Number: c.Number, Paths: c.Paths, Beside: map[string]builder.Beside{},
 		Modules: c.Modules, New: c.New, Manifests: c.Manifests, Judge: c.Judge, Base: c.Base,
-		Toolchain: builder.ToolchainOf(request.Held), Toolchains: builder.ToolchainsOf(request.Held)}
+		Toolchain: builder.ToolchainOf(request.Held), Toolchains: builder.ToolchainsOf(request.Held),
+		Tests: c.Tests, StoreOnly: c.StoreOnly}
 	for dir, b := range c.Beside {
 		spec.Beside[dir] = builder.Beside{Repository: b.Repository, Ref: b.Ref}
 	}
@@ -472,11 +471,45 @@ func checkSpecOf(request link.BuildRequest) builder.CheckSpec {
 	return spec
 }
 
+// triedOf is a try's outcome as its log line says it (novox/hq issue 686): the repository's own check's verdict,
+// or the check's where that did not run — a head that does not merge — and the lines naming what failed.
+func triedOf(v builder.CheckVerdict) link.Tried {
+	t := link.Tried{Verdict: v.Verdict, Summary: v.Summary, Took: v.Took.Round(time.Second).String(),
+		Head: v.Head, Trunk: v.Trunk}
+	if v.Repo != nil && (v.Gate == nil || v.Gate.Verdict == "pass") {
+		t.Verdict, t.Summary = v.Repo.Verdict, v.Repo.Summary
+	}
+	if v.Repo != nil && v.Repo.Failed != "" {
+		t.Failed = strings.Split(v.Repo.Failed, "\n")
+	}
+	if t.Verdict == "" {
+		t.Verdict = "error"
+	}
+	return t
+}
+
+// namedOf are the builds the seat's verdicts name, as the builder believes a scratch record by them (novox/hq ADR
+// 0350 §2, issue 703): each module's key with every artifact's digest.
+func namedOf(builds []link.CheckedBuild) []builder.NamedBuild {
+	var out []builder.NamedBuild
+	for _, b := range builds {
+		named := builder.NamedBuild{Pull: builder.PullRef{Owner: b.Pull.Owner, Repo: b.Pull.Repo,
+			Number: b.Pull.Number}, Check: b.Check, Module: b.Built.Module, Key: b.Built.Key,
+			Digests: map[string]string{}}
+		for _, m := range b.Built.Made {
+			named.Digests[m.Name] = builder.DigestOf(m.Reference)
+		}
+		out = append(out, named)
+	}
+	return out
+}
+
 // checkBuiltOf is a check's builds for its merge as the outcome carries them (novox/hq ADR 0350 §1).
 func checkBuiltOf(built []builder.CheckBuilt) []link.CheckBuilt {
 	var out []link.CheckBuilt
 	for _, b := range built {
-		c := link.CheckBuilt{Module: b.Module, Key: b.Key, NotBuilt: b.NotBuilt, Took: b.Took.Round(time.Second).String()}
+		c := link.CheckBuilt{Module: b.Module, Key: b.Key, NotBuilt: b.NotBuilt, Took: b.Took.Round(time.Second).String(),
+			Kept: b.Kept}
 		for _, m := range b.Made {
 			c.Made = append(c.Made, link.MadeArtifact{Name: m.Name, Kind: m.Kind, Reference: m.Reference})
 		}

cmd/mesh-builder/tried_test.go

@@ -0,0 +1,31 @@
+package main
+
+import (
+	"testing"
+	"time"
+
+	"github.com/novox/mesh-controller/internal/builder"
+)
+
+// A try's outcome, as the build seat says it in the build's log (novox/hq issue 686): the repository's own
+// check's verdict, how long it took, and each line naming what failed.
+func TestATrysOutcomeNamesWhatFailed(t *testing.T) {
+	tried := triedOf(builder.CheckVerdict{Verdict: "pass", Summary: "the change touches no module", Took: 303 * time.Second,
+		Head: "c0ffee", Trunk: "ca3f43c", Gate: &builder.Layer{Verdict: "pass"},
+		Repo: &builder.Layer{Verdict: "fail", Summary: "its merge-check.sh failed: TestX",
+			Failed: "--- FAIL: TestX (0.01s)\n    x_test.go:12: got 1, want 2"}})
+	if tried.Verdict != "fail" || tried.Took != "5m3s" || len(tried.Failed) != 2 || tried.Trunk != "ca3f43c" ||
+		tried.Summary != "its merge-check.sh failed: TestX" {
+		t.Fatalf("a failed try: %+v", tried)
+	}
+	// A head that does not merge fails both layers: the check's own word.
+	conflict := triedOf(builder.CheckVerdict{Verdict: "fail", Summary: "does not merge", Gate: &builder.Layer{Verdict: "fail"},
+		Repo: &builder.Layer{Verdict: "fail", Summary: "does not merge"}})
+	if conflict.Verdict != "fail" || conflict.Summary != "does not merge" {
+		t.Fatalf("a try that does not merge: %+v", conflict)
+	}
+	// No verdict is an error, never a pass.
+	if none := triedOf(builder.CheckVerdict{}); none.Verdict != "error" {
+		t.Fatalf("a try with no verdict: %+v", none)
+	}
+}

cmd/mesh-controller/acting.go

@@ -26,8 +26,11 @@ import (
 //
 //   - **The serving controller** takes it before it does anything else — before it asserts the bus's
 //     objects, which are the controller's to write — waiting while another holds it, and renews it.
-//     A renewal refused or failed is the lease lost: the gate closes at once and the process exits, so
+//     Another holder seen, or the key's age passed with no renewal made, is the lease lost: the gate
-//     its service manager restarts it as a candidate (serve, in push.go).
+//     closes at once and the process exits, so its service manager restarts it as a candidate (serve,
+//     in push.go). A renewal the bus does not answer in time is not a loss (novox/hq issue 477): the
+//     lease is kept, no new act starts once half the key's age passed unrenewed, and the next renewal
+//     made opens the gate again.
 //   - **A command run at a shell** — `push` in the installer, the lab, a person repairing a mesh whose
 //     controller is down (issue 201) — acts **under the holder's epoch** when a controller holds the
 //     lease: it is the same mesh's word, composed and sent under the store's hold of each machine like

cmd/mesh-controller/batches.go

@@ -688,7 +688,7 @@ func spelledOf(m inventory.BatchedMerge) string {
 func namedOf(m inventory.BatchedMerge, repository string) inventory.PlanMerge {
 	k := announcedOf(m)
 	return inventory.PlanMerge{Repository: repository, Commit: m.Commit, Number: k.Number, Title: k.Title, Moves: k.Moves,
-		Merged: m.Merged, Heard: m.Heard}
+		Head: k.HeadSHA, Merged: m.Merged, Heard: m.Heard}
 }
 
 // laterMerge says a was merged after b: by the forge's merge time, then by when each was heard.

cmd/mesh-controller/bus_users_closed_test.go

@@ -0,0 +1,92 @@
+package main
+
+import (
+	"errors"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/novox/mesh-controller/internal/conditions"
+	"github.com/novox/mesh-controller/internal/link"
+)
+
+// **Every user's slow consumer is S9's, not the controller's alone** (novox/hq ADR 0357, issue 270). On
+// 2026-10-07 the bus closed two clients on the laptop as slow consumers and nothing raised a condition:
+// the controller heard only its own connection. Said by the bus module and read back, a user the bus
+// closes is one condition naming the module and its machine, raised at the first look and cleared an hour
+// after the last closure.
+func TestAUserTheBusClosedAsASlowConsumerIsOneConditionNamingItsModuleAndMachine(t *testing.T) {
+	closed := time.Date(2026, 10, 14, 12, 0, 0, 0, time.UTC)
+	now := closed.Add(20 * time.Second)
+	store := conditions.NewInMemory()
+	k := conditions.NewKeeper(t.Context(), conditions.Options{Store: store, History: store,
+		Teller: &conditions.Told{}, Now: func() time.Time { return now }})
+	t.Cleanup(func() { k.Close(t.Context()) })
+
+	advisories := link.BusClosures([]link.BusClosure{
+		{User: "laptop.claude-code", CID: 10, Reason: "Slow Consumer (Write Deadline)", Opened: closed.Add(-time.Hour),
+			Closed: closed.Add(-10 * time.Minute)},
+		{User: "laptop.claude-code", CID: 44, Reason: "Slow Consumer (Write Deadline)", Opened: closed.Add(-time.Minute),
+			Closed: closed},
+		{User: "anchor.desk", CID: 7, Reason: "Maximum Message Payload Exceeded", Opened: closed.Add(-time.Hour),
+			Closed: closed},
+	}, []string{link.AdvisorySlowConsumer, link.AdvisorySlowConsumer, link.AdvisoryConnectionClosed}, closed.Add(-time.Hour))
+	look := func() {
+		t.Helper()
+		f := &signalFacts{now: now, host: "anchor", advisories: advisories}
+		if err := k.Reconcile(t.Context(), "S9", watchAdvisories(f)); err != nil {
+			t.Fatal(err)
+		}
+	}
+	look()
+
+	slow, found, err := conditions.ReadOne(t.Context(), store, "bus.laptop.claude-code.slow-consumer")
+	if err != nil || !found {
+		t.Fatalf("no slow-consumer condition for the user: %v %v", found, err)
+	}
+	if slow.Subject.Machine != "laptop" || slow.Observations != 2 || !slow.LastObserved.Equal(closed) {
+		t.Fatalf("the slow consumer is said on %q, %d closure(s), last %s: %+v", slow.Subject.Machine, slow.Observations,
+			slow.LastObserved, slow)
+	}
+	if !strings.Contains(slow.Summary, "claude-code on laptop") || strings.Contains(slow.Summary, "laptop.claude-code") {
+		t.Fatalf("the summary does not name the module in words, or carries the dotted user: %q", slow.Summary)
+	}
+	if !strings.Contains(slow.Headline, "Claude-code on laptop") {
+		t.Fatalf("the headline is %q", slow.Headline)
+	}
+	cut, found, err := conditions.ReadOne(t.Context(), store, "bus.anchor.desk.connection-closed")
+	if err != nil || !found || cut.Subject.Machine != "anchor" || !strings.Contains(cut.Summary, "maximum message payload exceeded") {
+		t.Fatalf("the user cut off for breaking the bus's rules: %v %v %+v", found, err, cut)
+	}
+
+	// An hour after the newest closure without another, both clear.
+	now = closed.Add(time.Hour + time.Minute)
+	look()
+	for _, key := range []string{"bus.laptop.claude-code.slow-consumer", "bus.anchor.desk.connection-closed"} {
+		if _, found, _ := k.Get(t.Context(), key); found {
+			t.Fatalf("%s is still open an hour after the last closure", key)
+		}
+	}
+}
+
+// **A read of the bus module's events that fails does not blind S9** (review of #326): the controller's own
+// signals are still said, and the failed read is a condition of its own.
+func TestABusModuleReadThatFailsKeepsTheControllersOwnSignals(t *testing.T) {
+	at := time.Date(2026, 10, 14, 12, 0, 0, 0, time.UTC)
+	f := &signalFacts{now: at.Add(time.Minute), host: "anchor",
+		advisories: []link.Advisory{{Kind: link.AdvisorySlowConsumer, ID: "controller", Said: "the controller fell behind",
+			First: at, Last: at, Count: 1}},
+		busFaultsErr: errors.New("nats: timeout")}
+	keys := map[string]bool{}
+	for _, o := range watchAdvisories(f) {
+		keys[o.Key()] = true
+	}
+	if !keys["bus.controller.slow-consumer"] || !keys["bus.bus-module.bus-faults-unread"] {
+		t.Fatalf("observed %v: the controller's own slow consumer and the unread events, both", keys)
+	}
+	for _, row := range signalsTable {
+		if row.Row == "S9" && row.needs(f) != nil {
+			t.Fatal("the S9 row went blind for a read of the bus module's events")
+		}
+	}
+}

cmd/mesh-controller/check_builds_test.go

@@ -190,27 +190,90 @@ func TestAReusedCheckBuildIsRegisteredByItsDigestAndGatedAsABuiltOne(t *testing.
 	}
 }
 
-// A walk's leave names the builds its own pull requests' verdicts made, and none when they cannot be read: the
+// A walk's leave names the builds its own pull requests' verdicts made at the head each merge merged — never an
-// builder takes nothing a verdict does not name (novox/hq ADR 0350 §2).
+// earlier head's — read once per walk, and none when they cannot be read: the builder takes nothing a verdict does
+// not name (novox/hq ADR 0350 §2, issue 703).
 func TestAWalksLeaveNamesTheBuildsItsPullRequestsVerdictsMade(t *testing.T) {
 	was := checkedBuildsOf
-	t.Cleanup(func() { checkedBuildsOf = was })
+	forgetWalkVerdicts()
-	var asked []link.PullRef
+	t.Cleanup(func() { checkedBuildsOf = was; forgetWalkVerdicts() })
-	named := []link.CheckedBuild{{Pull: link.PullRef{Owner: "novox", Repo: "shop", Number: 7}, Check: "build-1",
+	var asked [][]link.PullRef
-		Built: link.CheckBuilt{Module: "app", Key: "r1:1"}}}
+	pull := link.PullRef{Owner: "novox", Repo: "shop", Number: 7}
+	atHead := link.CheckedBuild{Pull: pull, Check: "build-2", Head: "bbbbbbbbbbbb", Built: link.CheckBuilt{Module: "app", Key: "r1:2"}}
+	earlier := link.CheckedBuild{Pull: pull, Check: "build-1", Head: "aaaaaaaaaaaa", Built: link.CheckBuilt{Module: "app", Key: "r1:1"}}
 	checkedBuildsOf = func(_ context.Context, pulls []link.PullRef) ([]link.CheckedBuild, error) {
-		asked = pulls
+		asked = append(asked, pulls)
-		return named, nil
+		return []link.CheckedBuild{atHead, earlier}, nil
 	}
-	pulls := []link.PullRef{{Owner: "novox", Repo: "shop", Number: 7}}
+	pulls := []link.PullRef{pull}
-	if got := reuseWithVerdicts(t.Context(), &link.ReuseAsk{Pulls: pulls}); !reflect.DeepEqual(got.Builds, named) ||
+	heads := map[link.PullRef]string{pull: "bbbbbbbbbbbb0123456789"}
-		!reflect.DeepEqual(asked, pulls) {
+	for range 3 {
-		t.Fatalf("the leave names %+v, read for %+v", got.Builds, asked)
+		if got := reuseWithVerdicts(t.Context(), "plan-1", &link.ReuseAsk{Pulls: pulls}, heads); !reflect.DeepEqual(got.Builds,
+			[]link.CheckedBuild{atHead}) {
+			t.Fatalf("the leave names %+v, not only the merged head's build", got.Builds)
+		}
+	}
+	if !reflect.DeepEqual(asked, [][]link.PullRef{pulls}) {
+		t.Fatalf("the verdicts were read %d times for one walk: %v", len(asked), asked)
+	}
+	// A merge whose head was not said takes nothing.
+	if got := reuseWithVerdicts(t.Context(), "plan-1", &link.ReuseAsk{Pulls: pulls}, nil); got.Builds != nil {
+		t.Fatalf("a merge of no said head names %+v", got.Builds)
 	}
 	checkedBuildsOf = func(context.Context, []link.PullRef) ([]link.CheckedBuild, error) {
 		return nil, errors.New("no bus")
 	}
-	if got := reuseWithVerdicts(t.Context(), &link.ReuseAsk{Pulls: pulls}); got.Builds != nil {
+	if got := reuseWithVerdicts(t.Context(), "plan-2", &link.ReuseAsk{Pulls: pulls}, heads); got.Builds != nil {
 		t.Fatalf("verdicts that could not be read named %+v", got.Builds)
 	}
 }
+
+// A check is handed only the builds earlier checks of its own pull request at its own head made: another pull
+// request's build, or an earlier head's, is never kept (novox/hq issue 703). None when they cannot be read.
+func TestACheckIsHandedOnlyItsOwnHeadsBuilds(t *testing.T) {
+	was := checkedBuildsOf
+	t.Cleanup(func() { checkedBuildsOf = was })
+	pull := link.PullRef{Owner: "novox", Repo: "shop", Number: 7}
+	mine := link.CheckedBuild{Pull: pull, Check: "build-1", Head: "bbbbbbbbbbbb", Built: link.CheckBuilt{Module: "app", Key: "r1:1"}}
+	earlier := link.CheckedBuild{Pull: pull, Check: "build-0", Head: "aaaaaaaaaaaa", Built: link.CheckBuilt{Module: "app", Key: "r1:1"}}
+	another := link.CheckedBuild{Pull: link.PullRef{Owner: "novox", Repo: "shop", Number: 8}, Check: "build-9",
+		Head: "bbbbbbbbbbbb", Built: link.CheckBuilt{Module: "app", Key: "r1:1"}}
+	var asked [][]link.PullRef
+	checkedBuildsOf = func(_ context.Context, pulls []link.PullRef) ([]link.CheckedBuild, error) {
+		asked = append(asked, pulls)
+		return []link.CheckedBuild{mine, earlier, another}, nil
+	}
+	p := link.PullUpdated{Owner: "novox", Repo: "shop", Number: 7, Commit: "bbbbbbbbbbbb0123456789"}
+	builds := []link.CheckBuild{{Module: "app"}}
+	if got := namedForTheCheck(t.Context(), p, builds); !reflect.DeepEqual(got, []link.CheckedBuild{mine}) ||
+		!reflect.DeepEqual(asked, [][]link.PullRef{{pull}}) {
+		t.Fatalf("the check is handed %+v, read for %v", got, asked)
+	}
+	checkedBuildsOf = func(context.Context, []link.PullRef) ([]link.CheckedBuild, error) {
+		return nil, errors.New("no bus")
+	}
+	if got := namedForTheCheck(t.Context(), p, builds); got != nil {
+		t.Fatalf("verdicts that could not be read named %+v", got)
+	}
+}
+
+func forgetWalkVerdicts() {
+	walkVerdicts.Lock()
+	defer walkVerdicts.Unlock()
+	walkVerdicts.read = map[string]verdictsRead{}
+}
+
+// A walk's merged heads are the forge's word for each merge; a merge announced without its head, or a pull request
+// merged at two heads in one walk, has none, and its walk takes no check's build (novox/hq issue 703).
+func TestAWalksMergedHeadsAreTheForgesWord(t *testing.T) {
+	merge := func(number int, head string) inventory.PlanMerge {
+		return inventory.PlanMerge{Repository: "novox/shop", Number: number, Head: head}
+	}
+	p := &inventory.Plan{Delivery: &inventory.PlanDelivery{Merges: []inventory.PlanMerge{
+		merge(7, "aaaaaaaaaaaa1"), merge(8, ""), merge(9, "bbbbbbbbbbbb"), merge(9, "cccccccccccc")}}}
+	heads := mergedHeadsOf(p)
+	shop := func(n int) link.PullRef { return link.PullRef{Owner: "novox", Repo: "shop", Number: n} }
+	if heads[shop(7)] != "aaaaaaaaaaaa1" || heads[shop(8)] != "" || heads[shop(9)] != "" {
+		t.Fatalf("merged heads %v", heads)
+	}
+}

cmd/mesh-controller/checks.go

@@ -273,6 +273,7 @@ func checkRequestFor(ctx context.Context, open *stores, p link.PullUpdated, scop
 			}
 		}
 	}
+	builds := checkBuildsOf(p, scope, entries, clone)
 	return link.BuildRequest{
 		ID:         link.NewBuildID(time.Now()),
 		Repository: repository,
@@ -282,10 +283,35 @@ func checkRequestFor(ctx context.Context, open *stores, p link.PullUpdated, scop
 		Source:     sourceOnSeat(source),
 		Check: &link.CheckRequest{Owner: p.Owner, Repo: p.Repo, Number: p.Number, Base: p.Base,
 			Paths: p.Paths, Beside: beside, Modules: scope.Modules, Dependents: scope.Dependents, New: scope.New,
-			Manifests: scope.Manifests, Judge: scope.Judge, Builds: checkBuildsOf(p, scope, entries, clone)},
+			Manifests: scope.Manifests, Judge: scope.Judge, Builds: builds, Named: namedForTheCheck(ctx, p, builds)},
 	}, nil
 }
 
+// namedForTheCheck are the builds earlier checks of the same pull request at the same head named, read once for the
+// check (novox/hq issue 703): asked again because only the trunk moved, the check keeps what they built of a key
+// still the same. Another pull request's build, or one of an earlier head, is never kept. None when they cannot be
+// read, and the check builds, as before.
+func namedForTheCheck(ctx context.Context, p link.PullUpdated, builds []link.CheckBuild) []link.CheckedBuild {
+	if len(builds) == 0 || p.Commit == "" {
+		return nil
+	}
+	pull := link.PullRef{Owner: p.Owner, Repo: p.Repo, Number: p.Number}
+	read, err := checkedBuildsOf(ctx, []link.PullRef{pull})
+	if err != nil {
+		fmt.Printf("  the earlier checks' builds of %s/%s#%d could not be read, so the check builds: %v\n",
+			p.Owner, p.Repo, p.Number, err)
+		// empty-on-error: said above; a check handed no named build builds every module, as before issue 703
+		return nil
+	}
+	var named []link.CheckedBuild
+	for _, b := range read {
+		if b.Pull == pull && link.SameHead(b.Head, p.Commit) {
+			named = append(named, b)
+		}
+	}
+	return named
+}
+
 // checkBuildsOf are the modules a merge of the change would build, in the walk's order, as the check builds them
 // for the walk to take (novox/hq ADR 0350 §1): a module built from the repository checked, at the branch it merges
 // into, from the merge the check makes; any other — a module standing on one — from its own repository at the

cmd/mesh-controller/gate.go

@@ -1443,6 +1443,12 @@ func probeGates(ctx context.Context, d *doctor) ([]conditions.Observation, error
 	}
 	// A release held after a failed one, while builds still wait for a gate (ADR 0236).
 	out = append(out, backlogObservation()...)
+	// And a rest that went silent (novox/hq ADR 0353 §4).
+	silent, err := silentObservation(ctx, d.open.inventory)
+	if err != nil {
+		return nil, err
+	}
+	out = append(out, silent...)
 	return sortedFound(dedupeObservations(out)), nil
 }
 
@@ -1532,6 +1538,12 @@ func gateLine(g *inventory.PlanGate) string {
 	case inventory.GateFailed:
 		what = "FAILED"
 	}
+	switch {
+	case g.Verdict == "" && g.Pending:
+		what = "kept, not yet sent" // novox/hq ADR 0353 §8
+	case g.Verdict == "" && g.Silent:
+		what = "silent on its send, left" // ADR 0353 §4
+	}
 	if g.Verdict == "" && g.Waiting() {
 		what = "waits for a busy container on " + g.Busy.Machine
 	}

cmd/mesh-controller/held_back.go

@@ -151,7 +151,7 @@ func heldMachines(ctx context.Context, open *stores, names []string) (map[string
 		for _, mv := range f.moves(node, modules, same, known, false) {
 			if planStillToSend(plans, mv.Module, node) == "" {
 				why = append(why, fmt.Sprintf("%s would move from %s to %s, which has passed no gate yet — a release "+
-					"plan sends it, one machine at a time, judged", mv.Module, buildName(mv.From), buildName(mv.To)))
+					"plan sends it, one machine first and then the rest at once, judged", mv.Module, buildName(mv.From), buildName(mv.To)))
 			}
 		}
 		if len(why) > 0 {

cmd/mesh-controller/issue648_test.go

@@ -0,0 +1,87 @@
+package main
+
+import (
+	"encoding/json"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/novox/mesh-controller/internal/catalogue"
+	"github.com/novox/mesh-controller/internal/inventory"
+)
+
+// A tier whose module is no move — made from the source every machine running it runs, so nothing is
+// sent — is not waited on for a report after its marking (novox/hq issue 648). Its machines answered the
+// send that last carried that build before the walk got there, and nothing will make them report again:
+// the walk asks the next tier in the same step, rather than "waiting for app on anchor, laptop" for ever.
+func TestANoMoveTierWaitsForNoNewReport(t *testing.T) {
+	judgeLeavesAsTheCore(t)
+	g := aGateMesh(t)
+	ctx := t.Context()
+	inv := g.open.inventory
+
+	// app is the build machine, so a module of the next tier is built by it: the tier gates the next on app
+	// running on its machines.
+	for _, m := range []catalogue.Manifest{
+		{Module: "app", Version: "c2", Claims: []catalogue.Claim{{Name: "node-build-agent", Scope: catalogue.ScopeNode}}},
+		{Module: "web", Version: "w1"},
+	} {
+		if err := inv.RegisterModule(ctx, m, inventory.Source{Repository: "novox/mesh-catalog", Seat: "git",
+			Path: "modules/" + m.Module, BuiltFrom: m.Version, Head: m.Version, Asked: time.Now().Add(-time.Minute)}); err != nil {
+			t.Fatal(err)
+		}
+	}
+	// What anchor and laptop were last sent (c1) was made from the source the plan's build of c2 is.
+	for _, b := range []inventory.Build{
+		{ID: "build-1s", Module: "app", Commit: "c1", SourceFingerprint: "src1:app",
+			Asked: time.Now().Add(-30 * time.Second), At: time.Now().Add(-30 * time.Second)},
+		{ID: "build-2s", Module: "app", Commit: "c2", SourceFingerprint: "src1:app", Asked: time.Now(), At: time.Now()},
+	} {
+		b.Manifest, _ = json.Marshal(catalogue.Manifest{Module: "app", Version: "1"})
+		if err := inv.RecordBuild(ctx, b); err != nil {
+			t.Fatal(err)
+		}
+	}
+	// Each machine answered that send, applied, before the walk's tier was built.
+	for _, n := range []string{"anchor", "laptop"} {
+		if _, err := inv.RecordDoing(ctx, nodeID(t, g.open, n), inventory.Doing{Node: n,
+			Outcome: inventory.OutcomeApplied, Declared: "d-" + n + "-c1", Applied: 1,
+			At: time.Now().Add(-10 * time.Second)}); err != nil {
+			t.Fatal(err)
+		}
+	}
+	built := time.Now().UTC()
+	p := g.plan(t)
+	p.Tiers = [][]string{{"app"}, {"web"}}
+	p.Modules["app"].Build, p.Modules["app"].BuiltAt = "build-2s", &built
+	if err := inv.SavePlan(ctx, &p); err != nil {
+		t.Fatal(err)
+	}
+
+	advancePlans(ctx, g.open)
+
+	if len(g.sent) != 0 {
+		t.Fatalf("a no-move build was sent: %v", g.sent)
+	}
+	p = g.plan(t)
+	if s := p.Modules["app"]; s == nil || !strings.HasPrefix(s.Why, "no move") {
+		t.Fatalf("the build was not marked no move: %+v", s)
+	}
+	if p.Tier < 1 || strings.Contains(p.Note, "waiting for app") {
+		t.Fatalf("the walk waits on a no-move tier for a report nothing will cause: tier %d, %s %q", p.Tier, p.State, p.Note)
+	}
+
+	// A machine that has not answered its last send is still waited on: no move is not "never sent".
+	p.Tier, p.State, p.Note = 0, inventory.PlanRolling, ""
+	if err := inv.RecordSent(ctx, nodeID(t, g.open, "laptop"), "d-laptop-later", map[string]string{"app": "c1"}); err != nil {
+		t.Fatal(err)
+	}
+	if err := inv.SavePlan(ctx, &p); err != nil {
+		t.Fatal(err)
+	}
+	advancePlans(ctx, g.open)
+	p = g.plan(t)
+	if p.Tier != 0 || !strings.Contains(p.Note, "waiting for app on laptop") {
+		t.Fatalf("a machine that has not answered its last send was not waited on: tier %d, %q", p.Tier, p.Note)
+	}
+}

cmd/mesh-controller/main.go

@@ -106,6 +106,8 @@ func run() error {
 		return killCommand(ctx, args[1:])
 	case "forget-checks":
 		return forgetChecksCommand(ctx, args[1:])
+	case "try":
+		return tryCommand(ctx, args[1:])
 	case "pause", "resume":
 		return pauseCommand(ctx, args[0], args[1:])
 	case "collection":
@@ -381,6 +383,13 @@ func (b builds) Built(ctx context.Context, result link.BuildResult) error {
 	// **A merge check builds nothing** (novox/hq to-be 45 §9): its verdict is said, and nothing of it is
 	// recorded or registered.
 	if result.Check != nil || result.Checked != nil {
+		if isTry(result) {
+			// A branch tried before its pull request (novox/hq issue 686): its asker reads the outcome from the
+			// build's log. Never said as `checked`, so the forge's holder sets no status.
+			fmt.Printf("%s: a try of %s at %.8s, read with `try --id`: said to nobody, nothing taken in\n", result.ID,
+				result.Repository, result.Ref)
+			return nil
+		}
 		checked(ctx, result)
 		return nil
 	}

cmd/mesh-controller/module_health.go

@@ -240,6 +240,7 @@ func judgeModuleHealth(ctx context.Context, inv *inventory.Inventory, k *conditi
 			continue
 		}
 		o := moduleUnhealthyObservation(m, node, unhealthy[m])
+		declaredSeverity(&o, hold, m)
 		if hold != nil {
 			if by, held := hold.heldWith(node, m, unhealthy[m]); held {
 				// Held under the provider's condition: nothing of its own, and the provider's says it waits. The
@@ -347,6 +348,7 @@ func sayWaiters(ctx context.Context, k *conditions.Keeper, hold *holding, p cata
 	} else {
 		_, rest := besideAWait(p.Module, rs)
 		o = moduleUnhealthyObservation(p.Module, p.Node, rest)
+		declaredSeverity(&o, hold, p.Module)
 		if said, waits := personWait(p.Module, p.Node, rest); waits {
 			o = reloginObservation(p.Module, p.Node, said, operatorOn(ctx, hold.inv, p.Node), rest)
 		}
@@ -481,6 +483,19 @@ func sayWaitingOn(o *conditions.Observation, waiters []string) {
 	o.Explanation += fmt.Sprintf(" %d module(s) that depend on it wait for it.", len(waiters))
 }
 
+// declaredSeverity raises a module's unhealthy condition urgent when its manifest declares `unhealthy` urgent
+// (novox/hq ADR 0355 §1). Only that condition changes (ADR 0355 §4): a wait for a new login, a module that needs
+// the operator and a directory used as found keep their severities, and without the field, or without a manifest
+// to read it from, it stays the warning it was.
+func declaredSeverity(o *conditions.Observation, hold *holding, module string) {
+	if o.Kind != kindModuleUnhealthy || hold == nil {
+		return
+	}
+	if m, ok := hold.manifestOf(module); ok && m.UnhealthyIsUrgent() {
+		o.Severity = conditions.Urgent
+	}
+}
+
 // moduleUnhealthyObservation is a module unhealthy on a machine, in words: the summary names the module,
 // the machine and what is wrong with each resource; the detail — targets, streaks, since — is evidence.
 func moduleUnhealthyObservation(module, node string, rs []inventory.ResourceHealth) conditions.Observation {

cmd/mesh-controller/plain_words.go

@@ -456,6 +456,9 @@ var plainWordings = map[string]func(conditions.Observation) words{
 	"release-held": worded(func(o conditions.Observation) words {
 		return releaseHeldWords(nil, o.Also)
 	}),
+	"release-silent": worded(func(o conditions.Observation) words {
+		return releaseSilentWords(o.Also)
+	}),
 	"facts-stale": worded(func(o conditions.Observation) words {
 		return words{Headline: "Merge checks use outdated facts",
 			Explanation: "The facts a merge check judges a change against are out of date; they are gathered again " +
@@ -617,6 +620,18 @@ var plainWordings = map[string]func(conditions.Observation) words{
 			Explanation: "The bus reports a listener too slow to keep up, so messages to it are late.",
 			Resolved:    "The listener keeps up again"}
 	}),
+	kindBusFaultsUnread: worded(func(o conditions.Observation) words {
+		return words{Headline: "Slow clients of the bus cannot be checked",
+			Explanation: "The controller could not read what the bus said about its clients' connections, so a " +
+				"client the bus cut off would go unnoticed. It tries again at every check.",
+			Resolved: "Resolved: the bus's clients are checked again"}
+	}),
+	"connection-closed": worded(func(o conditions.Observation) words {
+		return words{Headline: "The bus cut a client off",
+			Explanation: "The bus closed a client's connection because it broke the bus's rules, so what it was " +
+				"sending was lost.",
+			Resolved: "Resolved: the client keeps to the bus's rules"}
+	}),
 	kindBusReconnects: worded(func(o conditions.Observation) words {
 		return words{Headline: "A client keeps losing the bus",
 			Explanation: "One of the mesh's clients lost its connection to the bus again and again in the last hour. " +
@@ -841,6 +856,19 @@ func releaseHeldWords(modules, machines []string) words {
 		Resolved: "Resolved: the held updates are released"}
 }
 
+// releaseSilentWords are the plain words of machines that said nothing on an update they were sent (ADR 0353 §4).
+func releaseSilentWords(machines []string) words {
+	where := "Some machines"
+	if len(machines) > 0 {
+		where = conditions.Capital(namesWords(machines, 4))
+	}
+	return words{Headline: "Machines did not answer an update",
+		Needs: "check that they are awake and on the mesh; the next walk sends them what waits.",
+		Explanation: where + " were sent module updates and said nothing about them within fifteen minutes, so " +
+			"they were left as they were. What they run is not known to be the update.",
+		Resolved: "Resolved: the next walk reached them"}
+}
+
 // reloginNeeds is what an account waiting for its groups needs (ADR 0252).
 func reloginNeeds(node string) string {
 	return fmt.Sprintf("log out of %s completely and log in again, or restart it.", node)

cmd/mesh-controller/release.go

@@ -39,8 +39,8 @@ import (
 //     from the same manifest is no move.
 //
 // **The release plan** is what walks the waiting moves through: whenever moves wait for a gate that no
-// started plan is walking, the mesh opens one — every such machine, one at a time, the control node last,
+// started plan is walking, the mesh opens one — every such machine, the first sent and judged, then the rest
-// each sent and judged before the next. A release plan that fails stops the next one opening on its own:
+// at once, each judged by its own gate (novox/hq ADR 0353, in place of one at a time). A release plan that fails stops the next one opening on its own:
 // a person releases it again (`upgrade release-backlog --why`), after the condition says why.
 
 // sendScope is what a send may carry that no gate has seen.
@@ -81,6 +81,15 @@ type moveFacts struct {
 	srcs   map[string]map[string]string
 	passed map[string]map[string]bool
 	plans  []inventory.Plan
+	// self is the release walking these moves, whose own gates are no other walk's (novox/hq ADR 0353).
+	self string
+}
+
+type walkingKey struct{}
+
+// withWalking says a release plan is the one sending: its own gates never hold its own sends back.
+func withWalking(ctx context.Context, id string) context.Context {
+	return context.WithValue(ctx, walkingKey{}, id)
 }
 
 func readMoveFacts(ctx context.Context, inv *inventory.Inventory) (moveFacts, error) {
@@ -99,6 +108,7 @@ func readMoveFacts(ctx context.Context, inv *inventory.Inventory) (moveFacts, er
 		return f, err
 	}
 	f.plans, err = inv.OpenPlans(ctx)
+	f.self, _ = ctx.Value(walkingKey{}).(string)
 	return f, err
 }
 
@@ -193,12 +203,18 @@ func (f moveFacts) moves(node string, modules []string, sent map[string]string,
 // feet. A release keeps no module records: its open gate's carried moves are its walk.
 func (f moveFacts) walkedBy(module, node, to string) string {
 	for _, p := range f.plans {
-		if !p.Open() {
+		if !p.Open() || (p.Release != nil && p.ID == f.self) {
 			continue
 		}
 		if p.Release != nil {
-			g := p.Release.Gate
+			// The first machine's gate, and every gate of the rest still judging (novox/hq ADR 0353).
-			if g == nil || g.Verdict != "" {
+			gates := []*inventory.PlanGate{p.Release.Gate}
+			for _, g := range p.Release.Gates {
+				gates = append(gates, g)
+			}
+			for _, g := range gates {
+				// A send kept and not yet made walks nothing yet (ADR 0353 §8).
+				if g == nil || g.Verdict != "" || g.Silent || g.Pending {
 					continue
 				}
 				for _, c := range g.Carried {
@@ -206,6 +222,7 @@ func (f moveFacts) walkedBy(module, node, to string) string {
 						return p.ID
 					}
 				}
+			}
 			continue
 		}
 		s, holds := p.Modules[module]
@@ -303,8 +320,8 @@ func ungatedIn(ctx context.Context, open *stores, names []string, addedHolder st
 		}
 	}
 	if len(refused) > 0 {
-		return nil, fmt.Errorf("%w: %s — a walk sends them, one machine at a time, each judged (novox/hq ADR "+
+		return nil, fmt.Errorf("%w: %s — a walk sends them, one machine first and then the rest at once, each judged (novox/hq ADR "+
-			"0236); `upgrade backlog` lists them", errUngated, strings.Join(refused, "; "))
+			"0236, ADR 0353); `upgrade backlog` lists them", errUngated, strings.Join(refused, "; "))
 	}
 	return kept, nil
 }
@@ -320,19 +337,35 @@ func ungatedIn(ctx context.Context, open *stores, names []string, addedHolder st
 // And the grants step first, when the send changes what the bus's user list must say (novox/hq issue 490):
 // answered for the gate to keep, nil when there was none.
 func gatedSend(ctx context.Context, open *stores, node string, owns []inventory.CarriedMove) ([]inventory.CarriedMove, []string, *inventory.GrantsStep, error) {
-	inv := open.inventory
+	moves, err := gatedMoves(ctx, open, node, owns)
-	f, err := readMoveFacts(ctx, inv)
+	if err != nil || len(moves) == 0 {
+		return nil, nil, nil, err
+	}
+	sayRecreations(ctx, open, moves)
+	sent, grants, err := sendJudged(ctx, open, node)
 	if err != nil {
 		return nil, nil, nil, err
 	}
+	return moves, sent, grants, nil
+}
+
+// gatedMoves is what a gated send to one machine would carry, with the build each moves to, made of nothing:
+// gatedSend's reading, which a walk also keeps before it sends (novox/hq ADR 0353 §8). Refused the same way
+// while a plan that has started walks one of those builds elsewhere.
+func gatedMoves(ctx context.Context, open *stores, node string, owns []inventory.CarriedMove) ([]inventory.CarriedMove, error) {
+	inv := open.inventory
+	f, err := readMoveFacts(ctx, inv)
+	if err != nil {
+		return nil, err
+	}
 	moves, err := machineMoves(ctx, open, f, node, true)
 	if err != nil {
-		return nil, nil, nil, err
+		return nil, err
 	}
 	// A move the send keeps is not made, and is no move for the gate to judge (novox/hq issue 201): a core module
 	// kept over an older record judged as moving back to it would read the gate as superseded by its own send.
 	if moves, err = withoutKept(ctx, open, node, moves); err != nil {
-		return nil, nil, nil, err
+		return nil, err
 	}
 	own := func(module string) bool {
 		return slices.ContainsFunc(owns, func(o inventory.CarriedMove) bool { return o.Module == module })
@@ -342,7 +375,7 @@ func gatedSend(ctx context.Context, open *stores, node string, owns []inventory.
 			continue
 		}
 		if id := f.walkedBy(mv.Module, node, mv.To); id != "" {
-			return nil, nil, nil, fmt.Errorf("%w: %s's build %s waits on %s, which %s is walking", errWalkedElsewhere,
+			return nil, fmt.Errorf("%w: %s's build %s waits on %s, which %s is walking", errWalkedElsewhere,
 				mv.Module, short(mv.To), node, id)
 		}
 	}
@@ -350,7 +383,7 @@ func gatedSend(ctx context.Context, open *stores, node string, owns []inventory.
 	// plan, or a release, on this machine is not crossed with a newer build; this send waits for its gate.
 	for _, o := range owns {
 		if id := f.walkedBy(o.Module, node, o.To); id != "" {
-			return nil, nil, nil, fmt.Errorf("%w: %s's build %s waits on %s, which %s is walking", errWalkedElsewhere,
+			return nil, fmt.Errorf("%w: %s's build %s waits on %s, which %s is walking", errWalkedElsewhere,
 				o.Module, short(o.To), node, id)
 		}
 	}
@@ -363,30 +396,26 @@ func gatedSend(ctx context.Context, open *stores, node string, owns []inventory.
 			moves[i].Build = o.Build
 		}
 	}
-	if len(moves) == 0 && len(owns) == 0 {
+	if len(moves) == 0 {
-		return nil, nil, nil, nil
+		return nil, nil
 	}
 	for i := range moves {
 		if moves[i].Build == "" {
 			if moves[i].Build, err = inv.BuildOf(ctx, moves[i].Module, moves[i].To); err != nil {
-				return nil, nil, nil, err
+				return nil, err
 			}
 		}
 	}
 	sort.Slice(moves, func(i, j int) bool { return moves[i].Module < moves[j].Module })
-	sayRecreations(ctx, open, moves)
+	return moves, nil
-	sent, grants, err := sendJudged(ctx, open, node)
-	if err != nil {
-		return nil, nil, nil, err
-	}
-	return moves, sent, grants, nil
 }
 
 // passCarried keeps a pass as the verdict of every build the gate judged beside its own module.
 func passCarried(ctx context.Context, open *stores, p *inventory.Plan, g *inventory.PlanGate, except string) {
 	seen := map[string]bool{}
 	for _, c := range g.Carried {
-		if c.Module == except || c.Build == "" || seen[c.Build] {
+		// A build put back with another machine's failure is not this gate's to pass (novox/hq ADR 0353 §3).
+		if c.Module == except || c.Build == "" || seen[c.Build] || slices.Contains(g.Returned, c.Module) {
 			continue
 		}
 		seen[c.Build] = true
@@ -695,7 +724,7 @@ func releaseBacklog(ctx context.Context, open *stores, by string) (*inventory.Pl
 	p := inventory.Plan{ID: fmt.Sprintf("release-%d", now.UnixNano()), Repository: releaseRepository,
 		Created: now, State: inventory.PlanRolling, Tiers: [][]string{names}, Modules: map[string]*inventory.PlanModule{},
 		Release: &inventory.PlanRelease{Order: order, By: by},
-		Note: fmt.Sprintf("%d build(s) wait for a gate on %s; one machine at a time, each judged", len(names),
+		Note: fmt.Sprintf("%d build(s) wait for a gate on %s; one machine first, then the rest at once, each judged", len(names),
 			strings.Join(order, ", "))}
 	if err := inv.SavePlan(ctx, &p); err != nil {
 		return nil, err
@@ -704,14 +733,23 @@ func releaseBacklog(ctx context.Context, open *stores, by string) (*inventory.Pl
 	return &p, nil
 }
 
-// advanceRelease takes one step of a release plan: the next machine sent everything waiting there under a
+// advanceRelease takes one step of a release plan: the first machine sent everything waiting there under a
-// gate, or the machine being judged judged once more; the plan done when every machine is.
+// gate and judged; once it passed, every other machine sent at once, each under its own gate (novox/hq ADR
+// 0353 §1), and judged; the plan done when every machine is.
+//
+// **A send is kept before it is made** (ADR 0353 §8): the step that chooses a machine keeps its gate pending with
+// what it will carry, and the next step makes the send. A controller replaced between the send and keeping it
+// finds the gate pending, reads the machine's last send, and neither sends again nor leaves the machine unjudged.
 func advanceRelease(ctx context.Context, open *stores, p *inventory.Plan) (bool, error) {
 	r := p.Release
 	if r.Settings != nil {
 		return advanceSettingsWalk(ctx, open, p)
 	}
+	ctx = withWalking(ctx, p.ID)
 	now := time.Now().UTC()
+	if r.Rest {
+		return advanceRest(ctx, open, p, now)
+	}
 	if r.Gate == nil {
 		heard, err := releaseHeard(ctx, open)
 		if err != nil {
@@ -724,7 +762,7 @@ func advanceRelease(ctx context.Context, open *stores, p *inventory.Plan) (bool,
 				r.Next++
 				continue
 			}
-			moves, sent, grants, err := gatedSend(ctx, open, node, nil)
+			moves, err := gatedMoves(ctx, open, node, nil)
 			if errors.Is(err, errWalkedElsewhere) {
 				note := fmt.Sprintf("waiting before %s: %v", node, err)
 				changed := p.Note != note
@@ -732,23 +770,15 @@ func advanceRelease(ctx context.Context, open *stores, p *inventory.Plan) (bool,
 				return changed, nil
 			}
 			if err != nil {
-				return false, fmt.Errorf("sending %s what waits there: %w", node, err)
+				return false, fmt.Errorf("reading what waits on %s: %w", node, err)
 			}
 			if len(moves) == 0 {
 				r.Done = append(r.Done, node)
 				r.Next++
 				continue
 			}
-			r.Gate = &inventory.PlanGate{Machines: sent, Since: &now, Carried: moves, Sent: sentNow(ctx, open.inventory, sent),
+			r.Gate = &inventory.PlanGate{Machines: []string{node}, Carried: moves, Pending: true}
-				Grants: grants}
+			p.Note = fmt.Sprintf("sending %s %d build(s) that wait for a gate, first", node, len(moves))
-			p.Note = fmt.Sprintf("sent %s %d build(s) that waited for a gate; judging them there", node, len(moves))
-			if said := grantsSaid(grants); said != "" {
-				p.Note += "; " + said
-			}
-			if said := recreationsSaid(moves); said != "" {
-				p.Note += "; " + said
-			}
-			fmt.Printf("%s: %s\n", p.ID, p.Note)
 			return true, nil
 		}
 		p.State, p.Tier = inventory.PlanDone, len(p.Tiers)
@@ -759,6 +789,19 @@ func advanceRelease(ctx context.Context, open *stores, p *inventory.Plan) (bool,
 		return true, nil
 	}
 	g := r.Gate
+	if g.Pending {
+		node := firstOf(g.Machines)
+		out, err := sendKept(ctx, open, p, node, g, now)
+		if err != nil || out == keptWaiting {
+			return out == keptWaiting, err
+		}
+		if out == keptNothing {
+			r.Gate = nil
+			r.Done = append(r.Done, node)
+			r.Next++
+		}
+		return true, nil
+	}
 	verdict, err := judgeMoves(ctx, open, g, nil, now)
 	if err != nil {
 		return false, err
@@ -777,6 +820,11 @@ func advanceRelease(ctx context.Context, open *stores, p *inventory.Plan) (bool,
 		r.Done = append(r.Done, firstOf(g.Machines))
 		r.Next++
 		r.Gate = nil
+		// **Then the rest at once** (novox/hq ADR 0353 §1): every other machine heard from, each judged by its own
+		// gate, in place of one machine at a time (ADR 0236 §22).
+		r.Rest = true
+		p.Note = fmt.Sprintf("passed on %s; the rest are sent at once, each judged", firstOf(g.Machines))
+		fmt.Printf("%s: %s\n", p.ID, p.Note)
 		return true, nil
 	case inventory.GateSuperseded:
 		// Another send moved a judged module on the judged machine (novox/hq issue 352): no verdict on what
@@ -797,6 +845,453 @@ func advanceRelease(ctx context.Context, open *stores, p *inventory.Plan) (bool,
 	return true, nil
 }
 
+// What sendKept did with a kept send.
+const (
+	keptSent    = iota // sent now
+	keptAlready        // the machine was already sent it: judged from that send, nothing sent
+	keptNothing        // nothing waits there any more: no gate
+	keptWaiting        // another walk judges a build it would carry: it waits
+)
+
+// sendKept makes a send a gate kept before it was made (novox/hq ADR 0353 §8) — unless the machine's last send
+// already carries what the gate is for, made before a controller was replaced and before it was kept: then
+// nothing is sent, and the gate judges from that send (§6).
+func sendKept(ctx context.Context, open *stores, p *inventory.Plan, node string, g *inventory.PlanGate,
+	now time.Time) (int, error) {
+	inv := open.inventory
+	moves, sent, grants, err := gatedSend(ctx, open, node, nil)
+	if errors.Is(err, errWalkedElsewhere) {
+		p.Note = fmt.Sprintf("waiting before %s: %v", node, err)
+		return keptWaiting, nil
+	}
+	if err != nil {
+		return keptSent, fmt.Errorf("sending %s what waits there: %w", node, err)
+	}
+	if len(moves) > 0 {
+		g.Machines, g.Carried, g.Since, g.Grants, g.Pending = sent, moves, &now, grants, false
+		g.Sent = sentNow(ctx, inv, sent)
+		p.Note = fmt.Sprintf("sent %s %d build(s) that waited for a gate; judging them there", node, len(moves))
+		if said := grantsSaid(grants); said != "" {
+			p.Note += "; " + said
+		}
+		if said := recreationsSaid(moves); said != "" {
+			p.Note += "; " + said
+		}
+		fmt.Printf("%s: %s\n", p.ID, p.Note)
+		return keptSent, nil
+	}
+	if !alreadySent(ctx, inv, node, g.Carried) {
+		return keptNothing, nil
+	}
+	since := now
+	if s, found, err := inv.SentTo(ctx, node); err == nil && found {
+		if !s.At.IsZero() {
+			since = s.At
+		}
+		g.Sent = map[string]inventory.SentDeclaration{node: s}
+	}
+	g.Since, g.Pending = &since, false
+	p.Note = fmt.Sprintf("%s was already sent the %d build(s) kept for it, at %s: judged from that send, nothing sent again",
+		node, len(g.Carried), since.Local().Format("15:04:05"))
+	fmt.Printf("%s: %s\n", p.ID, p.Note)
+	return keptAlready, nil
+}
+
+// alreadySent says a machine's last send carries every build of the moves: a send made and not kept.
+func alreadySent(ctx context.Context, inv *inventory.Inventory, node string, moves []inventory.CarriedMove) bool {
+	if len(moves) == 0 {
+		return false
+	}
+	sent, known, err := inv.SentBuilds(ctx, node)
+	if err != nil || !known {
+		return false
+	}
+	for _, mv := range moves {
+		if !sameCommit(sent[mv.Module], mv.To) {
+			return false
+		}
+	}
+	return true
+}
+
+// advanceRest takes one step of a release plan's rest (novox/hq ADR 0353): the sends kept for a step made, every
+// machine of the step judged by its own gate, one that fails put back by itself while the others go on to their
+// verdicts, and the next step — or the end — once every gate of the step has its verdict or is silent.
+func advanceRest(ctx context.Context, open *stores, p *inventory.Plan, now time.Time) (bool, error) {
+	r := p.Release
+	// The sends kept for this step, in the plan's order: the control node, last in it, last (§1).
+	var pending []string
+	for _, n := range r.Order {
+		if g := r.Gates[n]; g != nil && g.Pending {
+			pending = append(pending, n)
+		}
+	}
+	if len(pending) > 0 {
+		// **A kept send carries only what was kept** (ADR 0353 §2): a build that passed no gate and came to wait on
+		// a machine since its step was chosen could reach a second machine in it; the step is chosen again.
+		if grew, err := keptStepGrew(ctx, open, r, pending); err != nil {
+			return false, err
+		} else if grew != "" {
+			for _, n := range pending {
+				delete(r.Gates, n)
+			}
+			opened, waiting, err := openRestStep(ctx, open, p)
+			if err != nil {
+				return true, err
+			}
+			p.Note = "chosen again: " + grew
+			if !opened && waiting != "" {
+				p.Note += "; " + waiting
+			}
+			return true, nil
+		}
+		var sent, already, waiting []string
+		for _, node := range pending {
+			out, err := sendKept(ctx, open, p, node, r.Gates[node], now)
+			if err != nil {
+				return true, err
+			}
+			switch out {
+			case keptSent:
+				sent = append(sent, node)
+			case keptAlready:
+				already = append(already, node)
+			case keptNothing:
+				delete(r.Gates, node)
+				r.Done = append(r.Done, node)
+			case keptWaiting:
+				waiting = append(waiting, node)
+			}
+		}
+		var said []string
+		if len(sent) > 0 {
+			said = append(said, "sent "+strings.Join(sent, ", ")+" at once, each judged there")
+		}
+		if len(already) > 0 {
+			said = append(said, strings.Join(already, ", ")+" already sent it: judged from that send")
+		}
+		if len(waiting) > 0 {
+			said = append(said, "waiting before "+strings.Join(waiting, ", ")+": another walk judges a build it carries")
+		}
+		if len(said) > 0 {
+			p.Note = strings.Join(said, "; ")
+		}
+		return len(sent)+len(already) > 0 || len(waiting) < len(pending), nil
+	}
+	reports, err := open.inventory.LastReports(ctx)
+	if err != nil {
+		return false, err
+	}
+	byNode := map[string]inventory.Reported{}
+	for _, rep := range reports {
+		byNode[rep.Node] = rep
+	}
+	changed, noteWas := false, p.Note
+	var notes, judging []string
+	batched, back := batchingRollbacks(ctx)
+	for _, node := range r.Order {
+		g := r.Gates[node]
+		if g == nil || g.Verdict != "" || g.Silent {
+			continue
+		}
+		// What another machine's failure already put back is not this gate's to judge (ADR 0353 §3).
+		if len(g.Carried) > 0 && len(g.Returned) >= len(g.Carried) {
+			decide(g, inventory.GateFailed, "what it was sent was put back with another machine's failure", now)
+			r.Failed = append(r.Failed, node)
+			changed = true
+			continue
+		}
+		// **A machine that says nothing on its send is left silent, not failed** (ADR 0353 §4): it is not judged
+		// until it reports, and past ApplySilentAfter it is listed and left.
+		if !reportedOnSend(byNode[node], node, g) {
+			if now.Sub(*g.Since) > inventory.ApplySilentAfter {
+				g.Silent = true
+				r.Silent = append(r.Silent, node)
+				changed = true
+				notes = append(notes, fmt.Sprintf("%s said nothing on its send within %s: left silent", node,
+					inventory.ApplySilentAfter))
+				continue
+			}
+			judging = append(judging, node+": not yet reported on its send")
+			continue
+		}
+		verdict, err := judgeMoves(ctx, open, g, nil, now)
+		if err != nil {
+			return changed, err
+		}
+		switch verdict {
+		case "":
+			if putBackBroken(ctx, open, p, g, "", nil) {
+				changed = true
+				notes = append(notes, p.Note)
+			}
+			judging = append(judging, node+": "+gateLine(g))
+		case inventory.GatePassed:
+			passCarried(ctx, open, p, g, "")
+			r.Done = append(r.Done, node)
+			changed = true
+		case inventory.GateSuperseded:
+			// Another send moved a judged module there (novox/hq issue 352): nothing judged, nothing put back on
+			// it; what still waits is released again.
+			r.Done = append(r.Done, node)
+			changed = true
+			notes = append(notes, fmt.Sprintf("superseded on %s: %s", node, g.Why))
+		default:
+			// **Put back by itself** (ADR 0353 §3): what was found wanting goes back at once, and every other
+			// machine of the step goes on to its own verdict.
+			stateWas := p.State
+			p.Note = ""
+			failCarried(batched, open, p, g, "")
+			p.State = stateWas
+			r.Failed = append(r.Failed, node)
+			changed = true
+			notes = append(notes, fmt.Sprintf("failed its gate on %s: %s — %s", node, g.Why, p.Note))
+			returnedElsewhere(ctx, open, r, node, g)
+		}
+	}
+	p.Note = ""
+	sendRollbacks(ctx, open, p, back)
+	if p.Note != "" {
+		notes = append(notes, strings.TrimPrefix(p.Note, "; "))
+	}
+	if len(judging) > 0 {
+		note := strings.Join(append(notes, "judging "+strings.Join(judging, "; ")), "; ")
+		p.Note = note
+		return changed || noteWas != note, nil
+	}
+	// Every gate of the step has its verdict or is silent: the next step, unless a machine failed (§3).
+	if len(r.Failed) == 0 {
+		opened, waiting, err := openRestStep(ctx, open, p)
+		if err != nil {
+			return changed, err
+		}
+		if opened {
+			return true, nil
+		}
+		if waiting != "" {
+			note := strings.Join(append(notes, waiting), "; ")
+			p.Note = note
+			return changed || noteWas != note, nil
+		}
+	}
+	p.Tier = len(p.Tiers)
+	end := fmt.Sprintf("released on %s", orNone(strings.Join(r.Done, ", ")))
+	if len(r.Silent) > 0 {
+		end += "; silent on their send, left: " + strings.Join(r.Silent, ", ")
+	}
+	if len(r.Skipped) > 0 {
+		end += "; not heard from, left as they were: " + strings.Join(r.Skipped, ", ")
+	}
+	p.State = inventory.PlanDone
+	if len(r.Failed) > 0 {
+		p.State = inventory.PlanFailed
+		end = "failed on " + strings.Join(r.Failed, ", ") + "; " + end
+	} else if len(r.Silent) > 0 && len(r.Gates) == len(r.Silent) {
+		// **A rest that said nothing is no success** (ADR 0353 §4): failure is loud; the condition says it.
+		p.State = inventory.PlanFailed
+		end = "no machine of the rest reported on its send; " + end
+	}
+	p.Note = strings.Join(append(notes, end), "; ")
+	fmt.Printf("%s: %s\n", p.ID, p.Note)
+	return true, nil
+}
+
+// keptStepGrew says why a step's kept sends would now carry a build no gate passed that they were not kept with;
+// empty when none would.
+func keptStepGrew(ctx context.Context, open *stores, r *inventory.PlanRelease, pending []string) (string, error) {
+	f, err := readMoveFacts(ctx, open.inventory)
+	if err != nil {
+		return "", err
+	}
+	shelf, err := open.inventory.Catalogue(ctx)
+	if err != nil {
+		return "", err
+	}
+	for _, node := range pending {
+		moves, err := gatedMoves(ctx, open, node, nil)
+		if errors.Is(err, errWalkedElsewhere) {
+			continue // sendKept says it waits
+		}
+		if err != nil {
+			return "", err
+		}
+		kept := r.Gates[node].Carried
+		for _, mv := range moves {
+			// The node-engine and the resolver keep one machine at a time, passed or not (ADR 0353 §9).
+			if (f.gated(mv.Module, mv.To) && !oneAtATime(mv.Module, shelf[mv.Module])) || slices.ContainsFunc(kept, func(c inventory.CarriedMove) bool {
+				return c.Module == mv.Module && sameCommit(c.To, mv.To)
+			}) {
+				continue
+			}
+			return fmt.Sprintf("%s's build %s, which this step did not keep for it, came to wait on %s", mv.Module, short(mv.To), node), nil
+		}
+	}
+	return "", nil
+}
+
+// reportedOnSend says a machine's last report is about the send its gate judges (novox/hq issue 352): the
+// declaration kept on the gate, or one sequenced after it; a gate that kept none reads the send made last.
+func reportedOnSend(r inventory.Reported, node string, g *inventory.PlanGate) bool {
+	if r.At == nil {
+		return false
+	}
+	if s, kept := g.Sent[node]; kept {
+		return s.ReportsOn(r)
+	}
+	return r.Current
+}
+
+// returnedElsewhere marks, on every other gate of the rest still judging, the builds a failed machine's
+// rollback put back wherever they were sent (ADR 0236 §5): no longer theirs to judge (ADR 0353 §3).
+func returnedElsewhere(ctx context.Context, open *stores, r *inventory.PlanRelease, failed string, g *inventory.PlanGate) {
+	for _, c := range g.Carried {
+		if c.Build == "" {
+			continue
+		}
+		if marked, err := open.inventory.GateFailed(ctx, c.Build); err != nil || !marked {
+			continue
+		}
+		for node, other := range r.Gates {
+			if node == failed || other.Verdict != "" || slices.Contains(other.Returned, c.Module) {
+				continue
+			}
+			for _, oc := range other.Carried {
+				if oc.Module == c.Module && sameCommit(oc.To, c.To) {
+					other.Returned = append(other.Returned, c.Module)
+				}
+			}
+		}
+	}
+}
+
+// openRestStep chooses the next step of a release plan's rest and keeps its sends (novox/hq ADR 0353 §1, §2):
+// every machine left that is heard from and has something waiting, except that a build no gate has passed goes
+// to one machine of the step only. Answers whether a step was kept, or why the walk waits.
+func openRestStep(ctx context.Context, open *stores, p *inventory.Plan) (bool, string, error) {
+	r := p.Release
+	heard, err := releaseHeard(ctx, open)
+	if err != nil {
+		return false, "", err
+	}
+	f, err := readMoveFacts(ctx, open.inventory)
+	if err != nil {
+		return false, "", err
+	}
+	waiting := map[string][]inventory.CarriedMove{}
+	var nodes, walked []string
+	for _, node := range r.Order[min(r.Next, len(r.Order)):] {
+		if r.Gates[node] != nil || slices.Contains(r.Done, node) || slices.Contains(r.Skipped, node) ||
+			slices.Contains(r.Failed, node) || slices.Contains(r.Silent, node) {
+			continue
+		}
+		if !heard[node] {
+			r.Skipped = append(r.Skipped, node)
+			continue
+		}
+		moves, err := gatedMoves(ctx, open, node, nil)
+		if errors.Is(err, errWalkedElsewhere) {
+			walked = append(walked, fmt.Sprintf("%s (%v)", node, err))
+			continue
+		}
+		if err != nil {
+			return false, "", fmt.Errorf("reading what waits on %s: %w", node, err)
+		}
+		if len(moves) == 0 {
+			r.Done = append(r.Done, node)
+			continue
+		}
+		waiting[node] = moves
+		nodes = append(nodes, node)
+	}
+	shelf, err := open.inventory.Catalogue(ctx)
+	if err != nil {
+		return false, "", err
+	}
+	step := restStep(nodes, waiting, f.gated, func(module string) bool { return oneAtATime(module, shelf[module]) })
+	if len(step) == 0 {
+		if len(walked) > 0 {
+			return false, "waiting before " + strings.Join(walked, "; "), nil
+		}
+		return false, "", nil
+	}
+	if r.Gates == nil {
+		r.Gates = map[string]*inventory.PlanGate{}
+	}
+	for _, node := range step {
+		r.Gates[node] = &inventory.PlanGate{Machines: []string{node}, Carried: waiting[node], Pending: true}
+	}
+	p.Note = fmt.Sprintf("sending %s at once, each judged there", strings.Join(step, ", "))
+	if left := len(nodes) - len(step); left > 0 {
+		p.Note += fmt.Sprintf("; %d machine(s) wait for a build that passed no gate yet to pass on one", left)
+	}
+	return true, "", nil
+}
+
+// oneAtATime is a module whose builds go to the rest one machine at a time (novox/hq ADR 0353 §9): the
+// node-engine, which applies every send, and a module holding the mesh's resolver, which names the bus.
+func oneAtATime(module string, m catalogue.Manifest) bool {
+	if module == hostModule {
+		return true
+	}
+	return slices.ContainsFunc(m.Claims, func(c catalogue.Claim) bool { return c.Name == resolverSeat })
+}
+
+// restStep is the machines of one step of the rest (novox/hq ADR 0353 §2), in the order given: each machine, unless
+// a build it would carry has passed no gate and an earlier machine of the step already carries it — that build's
+// first machine. Pure.
+//
+// **The node-engine and the mesh's resolver still go one machine at a time** (ADR 0353 §9): a step carries a
+// build of either to one machine only, judged before the next, since a fault that cuts a machine off the bus
+// shows only as its silence and no rollback reaches it.
+func restStep(nodes []string, waiting map[string][]inventory.CarriedMove, passed func(module, commit string) bool,
+	alone func(module string) bool) []string {
+	first := map[string]string{}
+	var out []string
+	for _, n := range nodes {
+		var unpassed []string
+		for _, mv := range waiting[n] {
+			if !passed(mv.Module, mv.To) || alone(mv.Module) {
+				unpassed = append(unpassed, mv.Module+"@"+mv.To)
+			}
+		}
+		if slices.ContainsFunc(unpassed, func(k string) bool { _, taken := first[k]; return taken }) {
+			continue
+		}
+		for _, k := range unpassed {
+			first[k] = n
+		}
+		out = append(out, n)
+	}
+	return out
+}
+
+// silentObservation is what the gate's probe says of the newest release whose rest went silent (novox/hq ADR 0353
+// §4): machines that never reported on their send, left as they were — loud, never a success said by nothing.
+func silentObservation(ctx context.Context, inv *inventory.Inventory) ([]conditions.Observation, error) {
+	recent, err := inv.RecentPlans(ctx, 20)
+	if err != nil {
+		return nil, err
+	}
+	for _, p := range recent {
+		if p.Release == nil || p.Release.Settings != nil || p.Open() {
+			continue
+		}
+		if len(p.Release.Silent) == 0 {
+			return nil, nil
+		}
+		machines := append([]string(nil), p.Release.Silent...)
+		sort.Strings(machines)
+		o := conditions.Observation{Scope: conditions.ScopeMesh, ID: "release", Token: "silent", Kind: "release-silent",
+			Severity: conditions.Warning, Resolver: conditions.ResolverOperator, Also: machines,
+			Summary: fmt.Sprintf("%s: %s said nothing on the send of the builds that waited for a gate within %s, and were "+
+				"left as they were", p.ID, strings.Join(machines, ", "), inventory.ApplySilentAfter)}
+		w := releaseSilentWords(machines)
+		o.Headline, o.Explanation, o.Resolved, o.Needs = w.Headline, w.Explanation, w.Resolved, w.Needs
+		return []conditions.Observation{o}, nil
+	}
+	return nil, nil
+}
+
 // backlogObservation is what the gate's probe says of a release held after a failure.
 func backlogObservation() []conditions.Observation {
 	if backlogNow.held == "" || len(backlogNow.waiting) == 0 {

cmd/mesh-controller/release_plan.go

@@ -9,6 +9,7 @@ import (
 	"slices"
 	"sort"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/nats-io/nats.go"
@@ -251,6 +252,20 @@ func gates(p inventory.Plan, edges []inventory.Edge, rollsOut func(string) bool)
 	return out
 }
 
+// noMoveWhy is what a plan says of a module of its tier whose build was made from the source every machine
+// running it runs (novox/hq issue 280): nothing is sent for it.
+// noMovePrefix opens it, and is what noMove reads: one prefix for the writer and the reader.
+const (
+	noMovePrefix = "no move"
+	noMoveWhy    = noMovePrefix + ": made from the source every machine running it runs"
+)
+
+// noMove is whether the plan marked the module no move and sent it nothing. Read from what the plan says,
+// so a plan kept before the mark had a name of its own is read the same (novox/hq issue 648).
+func noMove(s *inventory.PlanModule) bool {
+	return s != nil && s.FirstAt == nil && s.Gate == nil && strings.HasPrefix(s.Why, noMovePrefix)
+}
+
 // applied says whether every machine running the module has reported since the module was built.
 // appliedEach is applied with a moment of its own for each machine: the reports that count are the ones
 // after that machine was sent the build (novox/hq issue 256).
@@ -372,15 +387,73 @@ var checkedBuildsOf = func(ctx context.Context, pulls []link.PullRef) ([]link.Ch
 	return link.ReadCheckBuilds(ctx, js, buildSeatHeld(ctx), pulls, time.Now().Add(-builder.CheckBuildsKept))
 }
 
+// mergedHeadsOf are the head commits the walk's merges merged, by pull request (novox/hq issue 703): a pull request
+// merged twice in one walk, or whose head the announcement did not say, has none, and takes no check's build.
+func mergedHeadsOf(p *inventory.Plan) map[link.PullRef]string {
+	heads := map[link.PullRef]string{}
+	if p.Delivery == nil {
+		return heads
+	}
+	seen := map[link.PullRef]bool{}
+	for _, m := range p.Delivery.Merges {
+		pull, ok := pullOf(m)
+		if !ok {
+			continue
+		}
+		if seen[pull] && heads[pull] != m.Head {
+			heads[pull] = ""
+			continue
+		}
+		seen[pull] = true
+		heads[pull] = m.Head
+	}
+	return heads
+}
+
+// walkVerdicts are the checks' builds a walk read, by the walk's plan: read once per walk (novox/hq issue 649), not
+// once per module it asks for. Kept a day; a walk lasts minutes.
+var walkVerdicts = struct {
+	sync.Mutex
+	read map[string]verdictsRead
+}{read: map[string]verdictsRead{}}
+
+type verdictsRead struct {
+	at     time.Time
+	builds []link.CheckedBuild
+}
+
 // reuseWithVerdicts is a walk's leave with the builds its pull requests' verdicts name: the only builds the builder
-// may take (ADR 0350 §2). When they cannot be read the leave names none, and the walk builds, saying why.
+// may take (ADR 0350 §2), and **only those of a check of the head each merge merged** (novox/hq issue 703): a build
-func reuseWithVerdicts(ctx context.Context, r *link.ReuseAsk) *link.ReuseAsk {
+// a check made at an earlier head of the same pull request is never registered. Read once per walk. When they
+// cannot be read the leave names none, and the walk builds, saying why.
+func reuseWithVerdicts(ctx context.Context, walk string, r *link.ReuseAsk, heads map[link.PullRef]string) *link.ReuseAsk {
+	walkVerdicts.Lock()
+	read, known := walkVerdicts.read[walk]
+	walkVerdicts.Unlock()
+	if !known || walk == "" {
 		builds, err := checkedBuildsOf(ctx, r.Pulls)
 		if err != nil {
 			fmt.Printf("  the checks' builds of %d pull request(s) could not be read, so the walk builds: %v\n", len(r.Pulls), err)
 			return r
 		}
-	r.Builds = builds
+		read = verdictsRead{at: time.Now(), builds: builds}
+		if walk != "" {
+			walkVerdicts.Lock()
+			for id, w := range walkVerdicts.read {
+				if time.Since(w.at) > 24*time.Hour {
+					delete(walkVerdicts.read, id)
+				}
+			}
+			walkVerdicts.read[walk] = read
+			walkVerdicts.Unlock()
+		}
+	}
+	r.Builds = nil
+	for _, b := range read.builds {
+		if link.SameHead(b.Head, heads[b.Pull]) {
+			r.Builds = append(r.Builds, b)
+		}
+	}
 	return r
 }
 
@@ -423,7 +496,8 @@ func askModule(ctx context.Context, p *inventory.Plan, name string, byName map[s
 	}
 	// **The walk takes the check's build of the same key** (novox/hq ADR 0350 §2): its ask says so, with the pull
 	// requests it answers, whose checks name the part of a differing key.
-	id, err := askABuild(withReuse(ctx, reuseWithVerdicts(ctx, reuseAskOf(p))), source, e.Source.Path, ref)
+	id, err := askABuild(withReuse(ctx, reuseWithVerdicts(ctx, p.ID, reuseAskOf(p), mergedHeadsOf(p))), source,
+		e.Source.Path, ref)
 	if err != nil {
 		state.State = "failed"
 		state.Why = err.Error()
@@ -595,7 +669,7 @@ func advancePlans(ctx context.Context, open *stores) {
 		return
 	}
 	defer release()
-	// What waits for a gate, released one machine at a time (ADR 0236).
+	// What waits for a gate, released one machine first, then the rest at once (ADR 0236, ADR 0353).
 	if _, err := releaseBacklog(ctx, open, ""); err != nil {
 		fmt.Printf("plans: what waits for a gate could not be looked at: %v\n", err)
 	}
@@ -805,7 +879,7 @@ func advanceOnce(ctx context.Context, open *stores, p *inventory.Plan,
 			} else if same {
 				now := time.Now().UTC()
 				state.SentAt = &now
-				state.Why = "no move: made from the source every machine running it runs"
+				state.Why = noMoveWhy
 				fmt.Printf("%s: %s built from the source every machine running it runs: no move, nothing sent\n", p.ID, m)
 				continue
 			}
@@ -995,6 +1069,25 @@ func advanceOnce(ctx context.Context, open *stores, p *inventory.Plan,
 			if state.BuiltAt != nil {
 				since = *state.BuiltAt
 			}
+			// **A build that is no move is waited on by the send that last carried it** (novox/hq issue 648).
+			// Nothing was sent for it, so no report follows its marking or its build: a machine that does not
+			// happen to report again held the walk for ever. Each machine runs it once it answered its last
+			// send — the one whose builds made it no move — whenever that was.
+			if noMove(state) {
+				byNode := map[string]inventory.Reported{}
+				for _, r := range reports {
+					byNode[r.Node] = r
+				}
+				if ok, on := appliedEach(m, func(node string) time.Time {
+					if s := byNode[node].Sent; s != nil {
+						return *s
+					}
+					return time.Time{}
+				}, running, reports); !ok {
+					waiting = append(waiting, fmt.Sprintf("%s on %s", m, strings.Join(on, ", ")))
+				}
+				continue
+			}
 			// **Each machine from its own send** (novox/hq issue 256). With one machine first (ADR 0218)
 			// a module is sent twice — the first machine, then the rest — and SentAt is the second.
 			// Asked of every machine, the first machine's report, made between the two sends, read as
@@ -1056,10 +1149,36 @@ func firstSend(ctx context.Context, open *stores, p *inventory.Plan, node string
 	runningOf map[string][]string) error {
 	inv := open.inventory
 	before, beforeKnown, _ := inv.SentBuilds(ctx, node)
+	// **A machine already sent what this send is for is not sent again** (novox/hq ADR 0353 §6): sent by this plan
+	// before a controller was replaced and before it was kept, or by another walk. Judged from that send, and from
+	// the readings of a gate already judging it there.
+	// Only a send the machine reported it applied is one it has; one it never reported on is sent, as before
+	// (issue 280: what it ran before is then that build, and a failure leaves it as it was).
+	if beforeKnown && slices.IndexFunc(modules, func(m string) bool { return !sameCommit(before[m], p.Modules[m].Commit) }) < 0 &&
+		appliedLastSend(ctx, inv, node) {
+		if others, err := gatedMoves(ctx, open, node, nil); err == nil && len(others) == 0 {
+			adoptSend(ctx, open, p, node, modules, before, runningOf)
+			return nil
+		}
+	}
+	// **What the machine ran before is kept before the send is made** (novox/hq ADR 0353 §6): a controller replaced
+	// between the send and keeping it reads it here, and a failure still puts the machine back.
+	kept := false
+	for _, m := range modules {
+		s := p.Modules[m]
+		if beforeKnown && (s.Previous == "" || !sameCommit(before[m], s.Commit)) && s.Previous != before[m] {
+			s.Previous, kept = before[m], true
+		}
+	}
+	if kept {
+		if err := inv.SavePlan(ctx, p); err != nil {
+			return fmt.Errorf("what %s ran before is not kept, so nothing is sent: %w", node, err)
+		}
+	}
 	owns := make([]inventory.CarriedMove, 0, len(modules))
 	for _, m := range modules {
 		s := p.Modules[m]
-		owns = append(owns, inventory.CarriedMove{Module: m, Node: node, From: before[m], To: s.Commit, Build: s.Build})
+		owns = append(owns, inventory.CarriedMove{Module: m, Node: node, From: s.Previous, To: s.Commit, Build: s.Build})
 	}
 	// A gated send (ADR 0236): everything waiting on the machine goes with the tier, and the gate judges
 	// all of it there.
@@ -1074,10 +1193,7 @@ func firstSend(ctx context.Context, open *stores, p *inventory.Plan, node string
 	sentWhat := sentNow(ctx, inv, sent)
 	for _, m := range modules {
 		s := p.Modules[m]
-		// What the first machine ran before: what a failed gate puts back (ADR 0236).
+		// What the first machine ran before (ADR 0236), kept above before the send.
-		if beforeKnown {
-			s.Previous = before[m]
-		}
 		s.First, s.FirstAt = sent, &now
 		s.Gate = &inventory.PlanGate{Component: coreComponent(m), Machines: firstRunning(sent, runningOf[m]),
 			From: s.Previous, To: s.Commit, Since: &now, Sent: sentWhat}
@@ -1106,6 +1222,113 @@ func firstSend(ctx context.Context, open *stores, p *inventory.Plan, node string
 	return nil
 }
 
+// adoptSend records a first send the machine already had (novox/hq ADR 0353 §6, §7): nothing is sent; the gate counts
+// from the machine's last send, and takes over the readings of an open gate of another walk judging the same build
+// there — whose carried move also says what the machine ran before, for a rollback.
+func adoptSend(ctx context.Context, open *stores, p *inventory.Plan, node string, modules []string,
+	before map[string]string, runningOf map[string][]string) {
+	inv := open.inventory
+	since := time.Now().UTC()
+	last, found, err := inv.SentTo(ctx, node)
+	if err == nil && found && !last.At.IsZero() {
+		since = last.At
+	}
+	lead := modules[0]
+	other, id, from := judgingThere(ctx, inv, p.ID, lead, node, p.Modules[lead].Commit, p.Modules[lead].Build)
+	for _, m := range modules {
+		s := p.Modules[m]
+		// What it ran before: kept by this walk before its send was made (§6); else what the other walk's send
+		// moved it from; else the build itself, so a failure leaves it as it was (issue 280).
+		switch {
+		case s.Previous != "":
+		case m == lead && from != "":
+			s.Previous = from
+		default:
+			s.Previous = before[m]
+		}
+		at := since
+		s.First, s.FirstAt = []string{node}, &at
+		s.Gate = &inventory.PlanGate{Component: coreComponent(m), Machines: firstRunning([]string{node}, runningOf[m]),
+			From: s.Previous, To: s.Commit, Since: &at}
+		if found {
+			s.Gate.Sent = map[string]inventory.SentDeclaration{node: last}
+		}
+		s.GatedBy = ""
+		if m == lead {
+			s.Gate.TakeReadings(other, modules, id)
+		} else {
+			s.GatedBy = lead
+		}
+	}
+	p.State = inventory.PlanRolling
+	p.Note = fmt.Sprintf("tier %d built; %s already runs %s's build: nothing sent again, judged from that send",
+		p.Tier, node, strings.Join(modules, ", "))
+	if id != "" {
+		p.Note += ", going on from the readings of " + id
+	}
+	fmt.Printf("%s: %s\n", p.ID, p.Note)
+}
+
+// appliedLastSend says a machine reported it applied the declaration it was sent last.
+func appliedLastSend(ctx context.Context, inv *inventory.Inventory, node string) bool {
+	reports, err := inv.LastReports(ctx)
+	if err != nil {
+		return false
+	}
+	for _, r := range reports {
+		if r.Node == node {
+			return r.Current && r.At != nil && r.Outcome == inventory.OutcomeApplied
+		}
+	}
+	return false
+}
+
+// judgingThere is an open gate of another walk judging a module's build on a machine (novox/hq ADR 0353 §7), the
+// walk's id, and what the machine ran before; nil when none does.
+func judgingThere(ctx context.Context, inv *inventory.Inventory, self, module, node, commit, build string) (*inventory.PlanGate, string, string) {
+	plans, err := inv.OpenPlans(ctx)
+	if err != nil {
+		return nil, "", ""
+	}
+	// The same build, by its id where both name one, else by its commit.
+	same := func(b, c string) bool {
+		if b != "" && build != "" {
+			return b == build
+		}
+		return sameCommit(c, commit)
+	}
+	usable := func(g *inventory.PlanGate) bool {
+		return g != nil && !g.Pending && g.Since != nil && (g.Verdict == "" || g.Verdict == inventory.GatePassed) &&
+			slices.Contains(g.Machines, node)
+	}
+	for _, q := range plans {
+		if q.ID == self {
+			continue
+		}
+		if r := q.Release; r != nil {
+			gates := []*inventory.PlanGate{r.Gate}
+			for _, g := range r.Gates {
+				gates = append(gates, g)
+			}
+			for _, g := range gates {
+				if !usable(g) {
+					continue
+				}
+				for _, c := range g.Carried {
+					if c.Module == module && c.Node == node && same(c.Build, c.To) {
+						return g, q.ID, c.From
+					}
+				}
+			}
+			continue
+		}
+		if s := q.Modules[module]; s != nil && usable(s.Gate) && same(s.Build, s.Commit) {
+			return s.Gate, q.ID, s.Previous
+		}
+	}
+	return nil, "", ""
+}
+
 // passedWith keeps, on a module sent with others, the verdict of the gate that judged the send: the gate
 // on the first of them passed, and its pass was kept for every build it carried (passCarried).
 func passedWith(module string, s *inventory.PlanModule, lead string, g *inventory.PlanGate) {
@@ -1594,9 +1817,19 @@ func plansCommand(ctx context.Context, args []string) error {
 			// A release plan's walk (ADR 0236): machines done, the one judged, those to come.
 			fmt.Printf("  machines in order: %s; done: %s; skipped: %s\n", strings.Join(r.Order, ", "),
 				orNone(strings.Join(r.Done, ", ")), orNone(strings.Join(r.Skipped, ", ")))
-			if r.Gate != nil {
+			if len(r.Failed)+len(r.Silent) > 0 {
-				fmt.Printf("  %s\n", gateLine(r.Gate))
+				fmt.Printf("  failed: %s; silent: %s\n", orNone(strings.Join(r.Failed, ", ")), orNone(strings.Join(r.Silent, ", ")))
-				for _, c := range r.Gate.Carried {
+			}
+			gates := []*inventory.PlanGate{r.Gate}
+			for _, n := range r.Order {
+				gates = append(gates, r.Gates[n])
+			}
+			for _, g := range gates {
+				if g == nil {
+					continue
+				}
+				fmt.Printf("  %s\n", gateLine(g))
+				for _, c := range g.Carried {
 					fmt.Printf("    %-22s %s → %s\n", c.Module, short(c.From), short(c.To))
 					if c.Recreates != "" {
 						fmt.Printf("    %-22s %s\n", "", c.Recreates)

cmd/mesh-controller/rest_at_once_test.go

@@ -0,0 +1,372 @@
+package main
+
+import (
+	"context"
+	"slices"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/novox/mesh-controller/internal/catalogue"
+	"github.com/novox/mesh-controller/internal/inventory"
+)
+
+// novox/hq ADR 0353: after its first machine passes, a build goes to every other machine at once, each judged by
+// its own gate and a failing one put back by itself; and a gate's readings outlive the controller that took them —
+// a machine already sent what a send is for is not sent again, and its judging goes on from what was read.
+//
+// Seen 2026-10-14: release-1791930194184991192 sent ace, g14, shanks and the control node one after another in
+// eleven minutes; the new controller its last send started sent the control node again the controller build it
+// had just applied, and judged it from its first reading.
+
+// aBacklogOnThree is the backlog fixture with a third machine, desk, running app at c1 like the others.
+func aBacklogOnThree(t *testing.T) *backlogMesh {
+	t.Helper()
+	b := aBacklog(t)
+	ctx := t.Context()
+	inv := b.open.inventory
+	if _, err := inv.AddNode(ctx, "desk"); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := inv.Assign(ctx, "desk", "app"); err != nil {
+		t.Fatal(err)
+	}
+	if err := inv.RecordSent(ctx, nodeID(t, b.open, "desk"), "d-desk", map[string]string{"app": "c1"}); err != nil {
+		t.Fatal(err)
+	}
+	wasHeard := releaseHeard
+	releaseHeard = func(context.Context, *stores) (map[string]bool, error) {
+		return map[string]bool{"anchor": true, "laptop": true, "desk": true}, nil
+	}
+	t.Cleanup(func() { releaseHeard = wasHeard })
+	return b
+}
+
+// events records every send and every judging, in order.
+func events(t *testing.T) *[]string {
+	t.Helper()
+	var said []string
+	wasSend, wasGather := sendRollout, gatherGateFacts
+	sendRollout = func(ctx context.Context, open *stores, names []string) ([]string, error) {
+		said = append(said, "send "+strings.Join(names, ","))
+		return wasSend(ctx, open, names)
+	}
+	gatherGateFacts = func(ctx context.Context, open *stores, component string) (gateFacts, error) {
+		said = append(said, "judge")
+		return wasGather(ctx, open, component)
+	}
+	t.Cleanup(func() { sendRollout, gatherGateFacts = wasSend, wasGather })
+	return &said
+}
+
+// Once the first machine passed, the rest are both sent before either is judged (ADR 0353 §1); before, the second
+// was judged to its verdict before the third was sent.
+func TestAReleaseSendsTheRestAtOnceAfterTheFirstPasses(t *testing.T) {
+	judgeLeavesAsTheCore(t)
+	b := aBacklogOnThree(t)
+	ctx := t.Context()
+	said := events(t)
+	gateEvery = 0
+	for i := 0; i < 12; i++ {
+		advancePlans(ctx, b.open)
+	}
+	p := b.release(t)
+	if p.State != inventory.PlanDone || len(p.Release.Done) != 3 {
+		t.Fatalf("the release is %s: %s %+v", p.State, p.Note, p.Release)
+	}
+	desk, laptop := slices.Index(*said, "send desk"), slices.Index(*said, "send laptop")
+	if desk < 0 || laptop < 0 || slices.Index(*said, "send anchor") > min(desk, laptop) {
+		t.Fatalf("sends and judgings: %v", *said)
+	}
+	if slices.Contains((*said)[min(desk, laptop):max(desk, laptop)], "judge") {
+		t.Fatalf("the rest were sent one at a time, each judged before the next: %v", *said)
+	}
+	if v, found, err := b.open.inventory.GateOf(ctx, "build-late-c2"); err != nil || !found || v.Verdict != inventory.GatePassed {
+		t.Fatalf("late's pass on laptop was not kept: %+v %v %v", v, found, err)
+	}
+}
+
+// A machine of the rest whose gate fails is put back at once, and the other machine of the step goes on to its own
+// verdict (ADR 0353 §3); before, the walk stopped at the failure and the machine after it was never sent.
+func TestARestMachineThatFailsIsPutBackAloneAndTheOthersAreJudgedOn(t *testing.T) {
+	judgeLeavesAsTheCore(t)
+	b := aBacklogOnThree(t)
+	ctx := t.Context()
+	inv := b.open.inventory
+	gateEvery = 0
+	b.broken["desk"] = true // desk fails what it is sent in the rest's step
+	advancePlans(ctx, b.open)
+	for i := 0; i < 12 && b.release(t).Open(); i++ {
+		advancePlans(ctx, b.open)
+	}
+	p := b.release(t)
+	if p.State != inventory.PlanFailed || !slices.Equal(p.Release.Failed, []string{"desk"}) {
+		t.Fatalf("the release is %s: %s %+v", p.State, p.Note, p.Release)
+	}
+	if !slices.ContainsFunc(b.sent, func(s []string) bool { return slices.Equal(s, []string{"laptop"}) }) {
+		t.Fatalf("laptop was never sent: %v", b.sent)
+	}
+	if !slices.Contains(p.Release.Done, "laptop") {
+		t.Fatalf("laptop has no verdict of its own: %+v", p.Release)
+	}
+	// late waited on laptop alone and was healthy there: its pass is kept, whatever desk did.
+	if v, found, err := inv.GateOf(ctx, "build-late-c2"); err != nil || !found || v.Verdict != inventory.GatePassed {
+		t.Fatalf("late's pass on laptop was not kept: %+v %v %v", v, found, err)
+	}
+	// app failed on desk: marked, and put back wherever it was sent (ADR 0236).
+	if failed, _ := inv.GateFailed(ctx, "build-app-c2"); !failed {
+		t.Fatal("app's build is not marked failed")
+	}
+	if sent, _, _ := inv.SentBuilds(ctx, "desk"); sent["app"] != "c1" {
+		t.Fatalf("desk was not put back: %v", sent)
+	}
+}
+
+// A walk whose first machine already runs its build under another walk's gate sends nothing and goes on from that
+// gate's readings (ADR 0353 §7); before, it sent the machine again and judged from its first reading.
+func TestAWalkTakesOverTheReadingsOfAGateJudgingTheSameBuildThere(t *testing.T) {
+	judgeLeavesAsTheCore(t)
+	b := aBacklog(t)
+	ctx := t.Context()
+	inv := b.open.inventory
+	advancePlans(ctx, b.open) // the release sends anchor app c2, and reads it once
+	release := b.release(t)
+	judging := release.Release.Gate
+	if judging == nil || judging.Pending || judging.Passes == 0 {
+		t.Fatalf("the release is not judging anchor: %+v", judging)
+	}
+	built := time.Now().UTC()
+	plan := inventory.Plan{ID: "plan-app", Repository: "novox/mesh-catalog", Branch: "main", Commit: "c2",
+		Created: built, State: inventory.PlanBuilding, Tiers: [][]string{{"app"}},
+		Modules: map[string]*inventory.PlanModule{"app": {State: "built", BuiltAt: &built, Commit: "c2",
+			Build: "build-app-c2"}}}
+	if err := inv.SavePlan(ctx, &plan); err != nil {
+		t.Fatal(err)
+	}
+	advancePlans(ctx, b.open)
+	if len(b.sent) != 1 {
+		t.Fatalf("anchor was sent again what it runs: %v", b.sent)
+	}
+	p, err := inv.PlanByID(ctx, "plan-app")
+	if err != nil {
+		t.Fatal(err)
+	}
+	g := p.Modules["app"].Gate
+	if g == nil || g.Since == nil || !g.Since.Equal(*judging.Since) || g.Passes < judging.Passes || g.TookOver != release.ID {
+		t.Fatalf("the walk's gate starts from zero: %+v (the release's: %+v)", g, judging)
+	}
+	if p.Modules["app"].Previous != "c1" {
+		t.Fatalf("what anchor ran before is %q, not c1", p.Modules["app"].Previous)
+	}
+}
+
+// A walk's first send that was made and not kept — the controller replaced between the two — is not made again
+// by the controller that takes over: the gate counts from that send (ADR 0353 §5, §6).
+func TestAFirstSendMadeAndNotKeptIsNotSentAgain(t *testing.T) {
+	judgeLeavesAsTheCore(t)
+	g := aGateMesh(t)
+	ctx := t.Context()
+	// The old controller sends anchor app c2 and is replaced before it keeps the send.
+	made := sendRollout
+	sendRollout = func(ctx context.Context, open *stores, names []string) ([]string, error) {
+		if _, err := made(ctx, open, names); err != nil {
+			return nil, err
+		}
+		return nil, context.Canceled
+	}
+	advancePlans(ctx, g.open)
+	sendRollout = made
+	if len(g.sent) != 1 || g.plan(t).Modules["app"].FirstAt != nil {
+		t.Fatalf("the fixture's send was not made, or was kept: %v", g.sent)
+	}
+	last, _, err := g.open.inventory.SentTo(ctx, "anchor")
+	if err != nil {
+		t.Fatal(err)
+	}
+	advancePlans(ctx, g.open)
+	if len(g.sent) != 1 {
+		t.Fatalf("the send was made again: %v", g.sent)
+	}
+	s := g.plan(t).Modules["app"]
+	if s.FirstAt == nil || s.Gate == nil || s.Gate.Since == nil || !s.Gate.Since.Equal(last.At) {
+		t.Fatalf("the gate does not count from the send made: %+v %+v", s, s.Gate)
+	}
+	// What anchor ran before was kept before the send, so a failure still puts it back (§5).
+	if s.Previous != "c1" || s.Gate.From != "c1" {
+		t.Fatalf("what anchor ran before is %q (gate from %q), not c1", s.Previous, s.Gate.From)
+	}
+}
+
+// A release's send kept before it was made, and made, is judged by the controller that takes over without being
+// made again (ADR 0353 §8).
+func TestAReleaseSendKeptAndMadeIsNotMadeAgain(t *testing.T) {
+	judgeLeavesAsTheCore(t)
+	b := aBacklog(t)
+	ctx := t.Context()
+	inv := b.open.inventory
+	p, err := releaseBacklog(ctx, b.open, "")
+	if err != nil || p == nil {
+		t.Fatalf("no release opened: %v", err)
+	}
+	if _, err := advanceRelease(ctx, b.open, p); err != nil || p.Release.Gate == nil || !p.Release.Gate.Pending {
+		t.Fatalf("the send was not kept before it was made: %+v %v", p.Release, err)
+	}
+	if err := inv.SavePlan(ctx, p); err != nil {
+		t.Fatal(err)
+	}
+	// The send is made, and the controller is replaced before it keeps it.
+	if _, err := sendRollout(ctx, b.open, []string{"anchor"}); err != nil {
+		t.Fatal(err)
+	}
+	advancePlans(ctx, b.open)
+	if len(b.sent) != 1 {
+		t.Fatalf("anchor was sent again: %v", b.sent)
+	}
+	g := b.release(t).Release.Gate
+	if g == nil || g.Pending || g.Since == nil || len(g.Carried) == 0 {
+		t.Fatalf("anchor is not judged on the send made: %+v", g)
+	}
+}
+
+// A build no gate has passed goes to one machine of a step, its first; a machine that would be its second waits
+// for the next step, and one whose every build passed goes now (ADR 0353 §2).
+func TestABuildThatPassedNoGateGoesToOneMachineOfAStep(t *testing.T) {
+	waiting := map[string][]inventory.CarriedMove{
+		"desk":   {{Module: "app", To: "c2"}, {Module: "new", To: "n1"}},
+		"laptop": {{Module: "app", To: "c2"}, {Module: "new", To: "n1"}},
+		"shanks": {{Module: "app", To: "c2"}},
+		"novox":  {{Module: "app", To: "c2"}, {Module: "ctl", To: "k1"}},
+	}
+	passed := func(module, commit string) bool { return module == "app" && commit == "c2" }
+	never := func(string) bool { return false }
+	step := restStep([]string{"desk", "laptop", "shanks", "novox"}, waiting, passed, never)
+	if !slices.Equal(step, []string{"desk", "shanks", "novox"}) {
+		t.Fatalf("the step is %v: laptop would be new's second machine before it passed", step)
+	}
+	if step := restStep([]string{"laptop"}, waiting, func(string, string) bool { return true }, never); !slices.Equal(step, []string{"laptop"}) {
+		t.Fatalf("a machine whose every build passed waits: %v", step)
+	}
+}
+
+// The node-engine and the mesh's resolver go to the rest one machine at a time, even passed (ADR 0353 §9): a step
+// carries either to one machine only, while what else passed goes everywhere at once.
+func TestTheNodeEngineAndTheResolverGoToTheRestOneAtATime(t *testing.T) {
+	waiting := map[string][]inventory.CarriedMove{
+		"desk":   {{Module: hostModule, To: "h2"}},
+		"laptop": {{Module: hostModule, To: "h2"}, {Module: "app", To: "c2"}},
+		"shanks": {{Module: "app", To: "c2"}},
+		"novox":  {{Module: "dns", To: "d2"}},
+		"ace":    {{Module: "dns", To: "d2"}},
+	}
+	resolver := catalogue.Manifest{Module: "dns", Claims: []catalogue.Claim{{Name: resolverSeat}}}
+	alone := func(m string) bool {
+		if m == "dns" {
+			return oneAtATime(m, resolver)
+		}
+		return oneAtATime(m, catalogue.Manifest{Module: m})
+	}
+	step := restStep([]string{"desk", "laptop", "shanks", "novox", "ace"}, waiting,
+		func(string, string) bool { return true }, alone)
+	if !slices.Equal(step, []string{"desk", "shanks", "novox"}) {
+		t.Fatalf("the step is %v: the node-engine and the resolver each reach one machine of it", step)
+	}
+	if oneAtATime("app", catalogue.Manifest{Module: "app"}) {
+		t.Fatal("a leaf module is held to one machine at a time")
+	}
+}
+
+// A first machine that fails still stops the walk (ADR 0236 §5, kept by ADR 0353 §3): the rest are never sent.
+func TestAFirstMachineThatFailsStillStopsTheWalk(t *testing.T) {
+	b := aBacklogOnThree(t)
+	ctx := t.Context()
+	gateEvery = 0
+	b.broken["anchor"] = true
+	advancePlans(ctx, b.open)
+	for i := 0; i < 6 && b.release(t).Open(); i++ {
+		advancePlans(ctx, b.open)
+	}
+	if p := b.release(t); p.State != inventory.PlanFailed || p.Release.Rest {
+		t.Fatalf("the release is %s: %s %+v", p.State, p.Note, p.Release)
+	}
+	for _, s := range b.sent {
+		if !slices.Equal(s, []string{"anchor"}) {
+			t.Fatalf("sent %v: the rest after a failed first machine", b.sent)
+		}
+	}
+}
+
+// The control node is sent last in a step of the rest (ADR 0353 §1): the machine holding the controller is
+// ordered after every other.
+func TestTheControlNodeIsSentLastInAStep(t *testing.T) {
+	judgeLeavesAsTheCore(t)
+	b := aBacklogOnThree(t)
+	ctx := t.Context()
+	register(t, b.open, catalogue.Manifest{Module: catalogue.ControllerSeatName, Version: "1"})
+	if _, err := b.open.inventory.Assign(ctx, "anchor", catalogue.ControllerSeatName); err != nil {
+		t.Fatal(err)
+	}
+	said := events(t)
+	gateEvery = 0
+	for i := 0; i < 12 && (len(b.sent) == 0 || b.release(t).Open()); i++ {
+		advancePlans(ctx, b.open)
+	}
+	if p := b.release(t); !slices.Equal(p.Release.Order, []string{"desk", "laptop", "anchor"}) {
+		t.Fatalf("the order is %v", p.Release.Order)
+	}
+	laptop, anchor := slices.Index(*said, "send laptop"), slices.Index(*said, "send anchor")
+	if laptop < 0 || anchor < laptop || slices.Contains((*said)[laptop:anchor], "judge") {
+		t.Fatalf("the control node is not sent last in the rest's step: %v", *said)
+	}
+}
+
+// A machine of the rest that says nothing on its send is left silent after fifteen minutes: not failed, not put
+// back; a rest that went silent whole ends failed, said as a condition (ADR 0353 §4).
+func TestARestMachineSilentPastItsBoundIsLeftAndSaid(t *testing.T) {
+	judgeLeavesAsTheCore(t)
+	b := aBacklog(t)
+	ctx := t.Context()
+	inv := b.open.inventory
+	reporting := sendRollout
+	sendRollout = func(ctx context.Context, open *stores, names []string) ([]string, error) {
+		if slices.Equal(names, []string{"laptop"}) { // laptop sleeps: sent, and says nothing
+			b.sent = append(b.sent, names)
+			current, _ := open.inventory.CurrentBuilds(ctx)
+			return names, open.inventory.RecordSent(ctx, nodeID(t, open, "laptop"), "d-laptop-asleep",
+				map[string]string{"app": current["app"].Commit, "late": current["late"].Commit, "same": current["same"].Commit})
+		}
+		return reporting(ctx, open, names)
+	}
+	t.Cleanup(func() { sendRollout = reporting })
+	gateEvery = 0
+	for i := 0; i < 8; i++ {
+		advancePlans(ctx, b.open)
+	}
+	p := b.release(t)
+	g := p.Release.Gates["laptop"]
+	if !p.Open() || g == nil || g.Verdict != "" || g.Silent {
+		t.Fatalf("laptop is judged before fifteen minutes: %s %s %+v", p.State, p.Note, g)
+	}
+	since := time.Now().Add(-inventory.ApplySilentAfter - time.Minute)
+	g.Since = &since
+	if err := inv.SavePlan(ctx, &p); err != nil {
+		t.Fatal(err)
+	}
+	advancePlans(ctx, b.open)
+	p = b.release(t)
+	if p.State != inventory.PlanFailed || !slices.Equal(p.Release.Silent, []string{"laptop"}) || len(p.Release.Failed) > 0 {
+		t.Fatalf("the release is %s: %s %+v", p.State, p.Note, p.Release)
+	}
+	if failed, _ := inv.GateFailed(ctx, "build-late-c2"); failed {
+		t.Fatal("a silent machine's build was marked failed")
+	}
+	if sent, _, _ := inv.SentBuilds(ctx, "laptop"); sent["late"] != "c2" {
+		t.Fatalf("laptop was put back: %v", sent)
+	}
+	obs, err := silentObservation(ctx, inv)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(obs) != 1 || obs[0].Kind != "release-silent" || !slices.Equal(obs[0].Also, []string{"laptop"}) {
+		t.Fatalf("the silence is not said: %+v", obs)
+	}
+}

cmd/mesh-controller/seatverbs.go

@@ -457,6 +457,28 @@ func (a *verbArguments) commandLine() ([]string, error) {
 			return nil, err
 		}
 		return []string{"forget-checks", str("owner"), str("repo"), str("number")}, nil
+	case "try":
+		// A branch tried before its pull request (novox/hq issue 686): asked, or read by the id it answered.
+		if id := str("id"); id != "" {
+			return []string{"try", "--id", id}, nil
+		}
+		if a.given["repository"] == "" && a.given["ref"] == "" {
+			// Neither shape named: the command says its usage, which names both, as `build` does.
+			return []string{"try"}, nil
+		}
+		if err := need("repository", "ref"); err != nil {
+			return nil, err
+		}
+		argv := []string{"try", str("repository"), str("ref")}
+		for _, flag := range []string{"base", "tests"} {
+			if v := str(flag); v != "" {
+				argv = append(argv, "--"+flag, v)
+			}
+		}
+		if on("store-only") {
+			argv = append(argv, "--store-only")
+		}
+		return argv, nil
 	case "cancel", "kill":
 		if err := need("id"); err != nil {
 			return nil, err
@@ -1018,6 +1040,8 @@ var jsonVerbs = map[string]bool{"status": true, "seats": true, "plan": true, "co
 	"delivery": true,
 	// The build queue, each ask with its position among the waiting (novox/hq issue 455).
 	"queue": true,
+	// A branch tried before its pull request (novox/hq issue 686).
+	"try": true,
 	// A plan followed (novox/hq issue 229): `plans wait` answers JSON; its other forms say text, and so answer no data.
 	"plans": true}
 
@@ -1308,6 +1332,10 @@ func seatToolHandlers() (map[string]link.ToolHandler, []string, error) {
 					link.AnswersWithin(ctx, bound+planWaitStart)
 				}
 			}
+			if verb == "try" && len(argv) > 1 && argv[1] == "--id" {
+				// Reading a try holds its answer for the verdict, up to its bound (novox/hq issue 686, 229).
+				link.AnswersWithin(ctx, tryWait+planWaitStart)
+			}
 			if answer, read := readHere(ctx, argv); read {
 				return answer, nil
 			}

cmd/mesh-controller/signals.go

@@ -153,11 +153,15 @@ var signalsTable = []signalRow{
 			return newestOf(f.standings, func(c conditions.Condition) time.Time { return c.LastObserved })
 		}},
 	{Row: "S9", Signal: "bus advisories: maximum deliveries, consumer deleted; the controller's own slow " +
-		"consumer and refused subjects", Emitter: "bus server's advisory subjects; the controller's connection",
+		"consumer and refused subjects; every user's connection the server closed as a slow consumer or for " +
+		"breaking the bus's rules (ADR 0357)",
+		Emitter: "bus server's advisory subjects; the controller's connection; the bus module's watch of its " +
+			"server (bus.slow-consumer, bus.connection-closed)",
 		Trigger: "any", Bound: "any occurrence; clears after an hour without another, a deleted consumer " +
 			"once it exists again or the mesh no longer expects it, and a message given up on once DEAD_LETTERS " +
 			"no longer holds it (novox/hq issue 330)",
-		Kind: "slow-consumer, max-deliveries, refused, consumer-lost", Severity: conditions.Warning, Phase: 1,
+		Kind: "slow-consumer, connection-closed, max-deliveries, refused, consumer-lost", Severity: conditions.Warning,
+		Phase: 1,
 		needs: func(f *signalFacts) error { return f.advisoriesErr }, watch: watchAdvisories,
 		newest: func(f *signalFacts) time.Time {
 			return newestOf(f.advisories, func(a link.Advisory) time.Time { return a.Last })
@@ -569,6 +573,9 @@ func watchAdvisories(f *signalFacts) []conditions.Observation {
 			// The advisory is remembered and read again on every look for an hour: the condition counts
 			// what the bus said and when, not the looks (novox/hq issue 402).
 			Happened: a.Last, Times: a.Count}
+		if a.User != "" && a.Reason != "" {
+			busUserClosed(&o, a, f.host)
+		}
 		if a.Kind == link.AdvisoryMaxDeliveries && a.Token == link.AdvisoryNotKept {
 			o.Machine = consumerMachine(a.Stream, a.Consumer)
 			o.Headline = clip(conditions.Capital(fmt.Sprintf("%s gave up on a message, not kept",
@@ -579,9 +586,58 @@ func watchAdvisories(f *signalFacts) []conditions.Observation {
 		}
 		out = append(out, o)
 	}
+	if f.busFaultsErr != nil {
+		out = append(out, busFaultsUnread(f.busFaultsErr))
+	}
 	return append(out, watchDeadLetters(f)...)
 }
 
+// kindBusFaultsUnread is the bus module's events not read back (novox/hq ADR 0357): every other user's
+// slow consumer is unheard while it lasts, and the controller's own signals are still said.
+const kindBusFaultsUnread = "bus-faults-unread"
+
+func busFaultsUnread(err error) conditions.Observation {
+	return conditions.Observation{Scope: conditions.ScopeBus, ID: "bus-module", Kind: kindBusFaultsUnread,
+		Severity: conditions.Warning, Confirm: true,
+		Summary: "what the bus module said of its users' connections could not be read back, so a slow consumer " +
+			"or a connection the bus closed is not said until it can",
+		Said: firstLine(err.Error())}
+}
+
+// busUserClosed words an advisory about a bus user's connection the server closed (novox/hq ADR 0357): the
+// user as the operator says it and the machine it is on, the dotted user name kept in the evidence only.
+func busUserClosed(o *conditions.Observation, a link.Advisory, host string) {
+	who, machine := busUserWords(a.User)
+	if machine == "" && a.User == "controller" {
+		machine = host
+	}
+	o.Machine = machine
+	times, count := "once", "once"
+	if a.Count > 1 {
+		times = fmt.Sprintf("%d times since %s", a.Count, a.First.UTC().Format("15:04 MST"))
+		count = fmt.Sprintf("%d times", a.Count)
+	}
+	switch a.Kind {
+	case link.AdvisorySlowConsumer:
+		o.Summary = fmt.Sprintf("the bus closed the connection of %s as a slow consumer %s in the last hour, "+
+			"newest at %s: it could not take what it was sent fast enough, and what was on its way to it was lost",
+			who, times, a.Last.UTC().Format("15:04 MST"))
+		o.Headline = clip(conditions.Capital(who)+" was too slow for the bus", 60)
+		o.Explanation = conditions.Capital(fmt.Sprintf("%s could not keep up with what the bus sent it, so the bus "+
+			"closed its connection (%s in the last hour) and what was on its way was lost. It connects again "+
+			"by itself; this clears an hour after the last time.", who, count))
+		o.Resolved = "Resolved: " + who + " kept up for an hour"
+	default:
+		o.Summary = fmt.Sprintf("the bus closed the connection of %s for breaking its rules %s in the last hour, "+
+			"newest at %s: %s", who, times, a.Last.UTC().Format("15:04 MST"), strings.ToLower(a.Reason))
+		o.Headline = clip(conditions.Capital(who)+" was cut off by the bus", 60)
+		o.Explanation = conditions.Capital(fmt.Sprintf("The bus closed the connection of %s because it broke "+
+			"the bus's rules (%s, %s in the last hour), so what it was sending was lost. This clears an hour "+
+			"after the last time.", who, strings.ToLower(a.Reason), count))
+		o.Resolved = "Resolved: " + who + " kept to the bus's rules for an hour"
+	}
+}
+
 // watchDeadLetters says each consumer that DEAD_LETTERS holds a message for (novox/hq issue 330): open
 // while it holds any, so it clears when they are delivered again or dropped, never because the server
 // stopped saying it.
@@ -806,7 +862,7 @@ func watchLease(f *signalFacts) []conditions.Observation {
 		}
 	}
 	if len(lost) > 0 {
-		how := "lost it: its renewal was refused or could not be made"
+		how := "lost it: another holder wrote its key, or no renewal was made within the key's age"
 		if newest.How == inventory.EpochExpired {
 			how = "stopped renewing it without giving it back, and was taken over"
 		}

cmd/mesh-controller/try.go

@@ -0,0 +1,353 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"flag"
+	"fmt"
+	"net/url"
+	"os"
+	"regexp"
+	"strings"
+	"time"
+
+	"github.com/nats-io/nats.go"
+
+	"github.com/novox/mesh-controller/internal/broker"
+	"github.com/novox/mesh-controller/internal/link"
+)
+
+// A branch is tried before its pull request (novox/hq issue 686).
+//
+// A repository's store tests skip without a store, and no agent may start a database on its machine. So a
+// builder pushed, a reviewer read, and only the pull request's merge check ran those tests for the first time:
+// each failure there cost a round of fifteen to thirty minutes (mesh-controller #283, #310, #312).
+//
+// `try <owner>/<repository> <ref>` asks the build seat for the repository's own check of a pushed branch or
+// commit, as the merge check runs it (internal/builder/check.go): the ref merged into the trunk's head, the
+// trunk's merge-check.sh, each part in its toolchain's container, against a throwaway store and bus. It is a
+// check and nothing more:
+//
+//   - **no pull request, so no status**: its outcome is never said as `checked`, which is what the forge's
+//     holder sets statuses from (isTry, in Built);
+//   - **nothing registered, nothing built**: it names no module of the graph, so the merge gate does not run and
+//     no build is made for a merge (novox/hq ADR 0350's scratch builds are a pull request's check's alone);
+//   - **a check in the build queue**: after deliveries (link.KindOf, novox/hq issue 558), and bounded by the
+//     check's own bound (checkTimeout);
+//   - **the code a pull request's check would run anyway**: only a repository of the mesh, whose every pull
+//     request the build seat already checks, in containers that hold no runtime socket.
+//
+// A check outlasts a seat verb's one answer, so the ask answers its id at once and `try --id <id>` reads what
+// came of it from the build's log, where the build seat says it whole (link.StepTried): holding its answer up
+// to tryWait for a verdict, like `plans wait` (novox/hq issue 229). Nothing is kept beside the log.
+
+// tryWait is how long reading a try holds its answer for the verdict. A variable so a test need not wait.
+var tryWait = 20 * time.Second
+
+// A ref as the forge is asked for it — a branch or a commit, never an option — and a `go test -run` pattern.
+var (
+	tryRef   = regexp.MustCompile(`^[A-Za-z0-9][A-Za-z0-9._/-]*$`)
+	tryTests = regexp.MustCompile(`^[A-Za-z0-9_^$|().*+?/\[\]-]+$`)
+)
+
+// tryAnswer is what `try` answers, asking or reading.
+type tryAnswer struct {
+	ID string `json:"id"`
+	// State is asked (just now), waiting (nothing said of it yet: in the build queue), running, or the verdict:
+	// pass, warning (the repository declares no merge-check.sh), fail, or error (it could not run).
+	State      string   `json:"state"`
+	Said       string   `json:"said"`
+	Repository string   `json:"repository,omitempty"`
+	Ref        string   `json:"ref,omitempty"`
+	Commit     string   `json:"commit,omitempty"`
+	Base       string   `json:"base,omitempty"`
+	Trunk      string   `json:"trunk,omitempty"`
+	On         string   `json:"on,omitempty"`
+	Took       string   `json:"took,omitempty"`
+	Failed     []string `json:"failed,omitempty"`
+	// Last is the last thing the build seat said of one still running.
+	Last string `json:"last,omitempty"`
+}
+
+// isTry says a check's outcome is a try's: marked so, or — echoed by a build seat from before the mark — a
+// check of no pull request and no group, which is nobody's status either.
+func isTry(result link.BuildResult) bool {
+	c := result.Checked
+	return c != nil && (c.Try || (c.Number == 0 && c.Group == ""))
+}
+
+// asATry makes a check's ask a try's: the repository's own script alone, for no pull request.
+func asATry(request link.BuildRequest, tests string, storeOnly bool) link.BuildRequest {
+	c := *request.Check
+	c.Number, c.Try, c.Tests, c.StoreOnly = 0, true, tests, storeOnly
+	c.Paths, c.Modules, c.New, c.Dependents, c.Manifests, c.Builds = nil, nil, nil, nil, nil, nil
+	c.Judge, c.Plan, c.Group, c.Members = "", nil, "", nil
+	request.Check = &c
+	return request
+}
+
+// maxTries is how many tries may wait or run at once, mesh-wide: each holds a build machine for minutes.
+const maxTries = 4
+
+// triesIn reads the build queue for a new try of one commit: the id of a try of that commit already waiting or
+// running — the answer to a second ask — and whether there is room for another.
+func triesIn(q link.Queue, owner, repo, commit string) (same string, room bool) {
+	n := 0
+	for _, a := range q.Asks {
+		if !link.IsTry(a.Request) || (a.State != link.AskWaiting && a.State != link.AskInFlight) {
+			continue
+		}
+		n++
+		c := a.Request.Check
+		if same == "" && strings.EqualFold(c.Owner, owner) && strings.EqualFold(c.Repo, repo) && a.Request.Ref == commit {
+			same = a.ID
+		}
+	}
+	return same, n < maxTries
+}
+
+// forgeCommit asks the forge, through its module's tools on the bus, which commit a branch or commit of a
+// repository is, and the repository's default branch. A variable so a test needs no forge.
+var forgeCommit = func(ctx context.Context, owner, repo, ref string) (commit, trunk string, err error) {
+	js, err := aBus()
+	if err != nil {
+		return "", "", err
+	}
+	defer js.Close()
+	bus := link.OverNATS{Conn: js.Conn()}
+	ask := func(path string, into any) error {
+		raw, _ := json.Marshal(map[string]any{"path": path})
+		answer, err := link.Ask(ctx, bus, "gitea", "gitea_api", raw, 30*time.Second)
+		if err != nil {
+			return err
+		}
+		if answer.Error != "" {
+			return errors.New(answer.Error)
+		}
+		return json.Unmarshal(answer.Result, into)
+	}
+	var commits struct {
+		Result []struct {
+			SHA string `json:"sha"`
+		} `json:"result"`
+	}
+	if err := ask("/repos/"+owner+"/"+repo+"/commits?limit=1&stat=false&verification=false&files=false&sha="+
+		url.QueryEscape(ref), &commits); err != nil {
+		return "", "", err
+	}
+	if len(commits.Result) == 0 || commits.Result[0].SHA == "" {
+		return "", "", errors.New("the forge named no commit for it")
+	}
+	var found struct {
+		Result struct {
+			DefaultBranch string `json:"default_branch"`
+		} `json:"result"`
+	}
+	if err := ask("/repos/"+owner+"/"+repo, &found); err != nil {
+		return "", "", err
+	}
+	return commits.Result[0].SHA, found.Result.DefaultBranch, nil
+}
+
+// tryCommand is `try <owner>/<repository> <ref> [--base <branch>] [--tests <pattern>] [--store-only]`, and
+// `try --id <id>` to read what came of one.
+func tryCommand(ctx context.Context, args []string) error {
+	set := flag.NewFlagSet("try", flag.ContinueOnError)
+	base := set.String("base", "", "the branch it is merged into (the repository's default branch when none)")
+	tests := set.String("tests", "", "only the tests this `go test -run` pattern names")
+	storeOnly := set.Bool("store-only", false, "only the repository's store tests")
+	id := set.String("id", "", "a try's id: what came of it")
+	positionals, err := parseAround(set, args)
+	if err != nil {
+		return err
+	}
+	usage := errors.New("try <owner>/<repository> <branch or commit> [--base <branch>] [--tests <pattern>] " +
+		"[--store-only], or try --id <id>")
+	if *id != "" {
+		if len(positionals) != 0 {
+			return usage
+		}
+		// Before it is a token of a bus subject: an id, never a pattern.
+		if !link.SafeBuildID(*id) {
+			return fmt.Errorf("%q is not a try's id", *id)
+		}
+		return tryRead(ctx, *id)
+	}
+	if len(positionals) != 2 {
+		return usage
+	}
+	owner, repo, isPath := strings.Cut(positionals[0], "/")
+	ref := positionals[1]
+	switch {
+	case !isPath || !tryRef.MatchString(owner) || !tryRef.MatchString(repo) || strings.Contains(repo, "/"):
+		return fmt.Errorf("%q is not a repository on the forge, owner/name; nothing was asked", positionals[0])
+	case !tryRef.MatchString(ref):
+		return fmt.Errorf("%q is not a branch or a commit; nothing was asked", ref)
+	case *base != "" && !tryRef.MatchString(*base):
+		return fmt.Errorf("%q is not a branch; nothing was asked", *base)
+	case *tests != "" && !tryTests.MatchString(*tests):
+		return fmt.Errorf("%q is not a `go test -run` pattern of test names; nothing was asked", *tests)
+	}
+	// **An unknown ref is refused here, loudly** — not sent to a machine to fail at its clone minutes later.
+	commit, trunk, err := forgeCommit(ctx, owner, repo, ref)
+	if err != nil {
+		return fmt.Errorf("the forge holds no branch or commit %s in %s/%s — is it pushed? — so nothing was asked: %w",
+			ref, owner, repo, err)
+	}
+	if *base != "" {
+		trunk = *base
+	}
+	if trunk == "" {
+		return fmt.Errorf("the forge named no default branch for %s/%s, and no --base says what %s is merged into; "+
+			"nothing was asked", owner, repo, ref)
+	}
+
+	open, err := openStores(ctx)
+	if err != nil {
+		return err
+	}
+	defer open.Close()
+	entries, read, edges, err := theGraph(ctx, open.inventory)
+	if err != nil {
+		return err
+	}
+	p := link.PullUpdated{Owner: owner, Repo: repo, Base: trunk, Commit: commit}
+	// Whose repository it is, as a pull request's check reckons it: only the mesh's is tried, the code the
+	// build seat runs for every pull request already.
+	mesh := pullScope(p, entries, read, edges)
+	if !mesh.Mesh {
+		return fmt.Errorf("%s/%s is no repository of the mesh — no module is built from it and its owner is not "+
+			"the core's — and only the mesh's are tried on the build seat; nothing was asked", owner, repo)
+	}
+	request, err := checkRequestFor(ctx, open, p, checkScope{Mesh: true, From: mesh.From}, entries)
+	if err != nil {
+		return err
+	}
+	request = asATry(request, *tests, *storeOnly)
+	seat := buildSeatHeld(ctx)
+	// **Bounded in number** (novox/hq issue 686): one try of a commit at a time, and maxTries in all.
+	js, err := dialTheBus()
+	if err != nil {
+		return err
+	}
+	queue, err := link.ReadQueue(ctx, js, seat)
+	js.Close()
+	if err != nil {
+		return err
+	}
+	same, room := triesIn(queue, owner, repo, commit)
+	if same != "" {
+		return printTry(tryAnswer{ID: same, State: "asked", Repository: owner + "/" + repo, Ref: ref, Commit: commit,
+			On: seat, Said: fmt.Sprintf("a try of %s/%s at %.12s already waits or runs, as %s: nothing new was asked. "+
+				"Read it with try id=%s", owner, repo, commit, same, same)})
+	}
+	if !room {
+		return fmt.Errorf("%d tries already wait or run on the build seat, the most at once (`queue` lists them); "+
+			"nothing was asked — read one of yours, or ask again when one has ended", maxTries)
+	}
+	ask, err := askOverOn(seat)
+	if err != nil {
+		return err
+	}
+	defer ask.Close()
+	if err := ask.Ask(ctx, request); err != nil {
+		return err
+	}
+	return printTry(tryAnswer{ID: request.ID, State: "asked", Repository: owner + "/" + repo, Ref: ref, Commit: commit,
+		Base: trunk, On: seat, Said: fmt.Sprintf("asked %s to try %s/%s at %.12s (%s) merged into %s: its own "+
+			"merge-check.sh, as a check in the build queue, bounded at %s; no status is set and nothing is registered. "+
+			"Read it with try id=%s — a full run of this kind takes minutes", seat, owner, repo, commit, ref, trunk,
+			checkTimeout, request.ID)})
+}
+
+// tryRead answers what came of a try, holding the answer up to tryWait for its verdict.
+func tryRead(ctx context.Context, id string) error {
+	until := time.Now().Add(tryWait)
+	for {
+		lines, err := buildLines(ctx, id)
+		if err != nil {
+			return err
+		}
+		a := tryAnswerOf(id, lines)
+		if (a.State != "waiting" && a.State != "running") || !time.Now().Add(2*time.Second).Before(until) {
+			return printTry(a)
+		}
+		if err := sleepOrDone(ctx, 2*time.Second); err != nil {
+			return err
+		}
+	}
+}
+
+// tryAnswerOf reads a try's answer from what the build seat said of it: its outcome under StepTried; `failed`
+// for one that could not run — an error, never a pass; else how far it is.
+func tryAnswerOf(id string, lines []link.BuildLine) tryAnswer {
+	a := tryAnswer{ID: id, State: "waiting", Said: "nothing is said of " + id + " yet: it waits in the build queue " +
+		"(`queue` says where), or no try has that id; ask again"}
+	for _, l := range lines {
+		switch l.Step {
+		case link.StepTried:
+			var t link.Tried
+			if err := json.Unmarshal([]byte(l.Message), &t); err != nil || t.Verdict == "" {
+				return tryAnswer{ID: id, State: "error", Said: "the build seat's word on it cannot be read: " + l.Message}
+			}
+			return tryAnswer{ID: id, State: t.Verdict, Said: t.Summary, Took: t.Took, Commit: t.Head, Trunk: t.Trunk,
+				Failed: t.Failed}
+		case "failed":
+			return tryAnswer{ID: id, State: "error", Said: "it could not run: " + l.Message}
+		case "checked":
+			// A check that is no try, or a build seat from before the verb: its verdict is not a try's.
+			return tryAnswer{ID: id, State: "error", Said: "the build seat checked it and said no try's outcome — " +
+				"it predates the verb (novox/hq issue 686), or " + id + " is no try: " + l.Message + "; `builds` with " +
+				"the id says every line"}
+		}
+		a.State, a.Last = "running", l.Message
+		a.Said = "still running; ask again. `builds` with the id says every line so far"
+	}
+	return a
+}
+
+func printTry(a tryAnswer) error {
+	fmt.Fprintln(os.Stderr, a.Said)
+	for _, l := range a.Failed {
+		fmt.Fprintln(os.Stderr, "    "+l)
+	}
+	out, err := json.MarshalIndent(a, "", "  ")
+	if err != nil {
+		return err
+	}
+	fmt.Println(string(out))
+	return nil
+}
+
+// buildLines is everything the build seat said of one build, as the bus keeps it, in order.
+func buildLines(ctx context.Context, id string) ([]link.BuildLine, error) {
+	js, err := aBus()
+	if err != nil {
+		return nil, fmt.Errorf("cannot reach the bus to read a build's log: %w", err)
+	}
+	defer js.Close()
+	subject := link.BuildLogOf("*", id)
+	sub, err := js.Context().PullSubscribe(subject, "",
+		nats.BindStream(broker.EventsStream), nats.DeliverAll(), nats.AckNone())
+	if err != nil {
+		return nil, fmt.Errorf("cannot read %s from the bus: %w", subject, err)
+	}
+	defer func() { _ = sub.Unsubscribe() }()
+	var lines []link.BuildLine
+	for {
+		batch, err := sub.Fetch(200, nats.MaxWait(2*time.Second))
+		if err != nil && !errors.Is(err, nats.ErrTimeout) && !errors.Is(err, context.DeadlineExceeded) {
+			return nil, fmt.Errorf("reading a build's log: %w", err)
+		}
+		for _, msg := range batch {
+			var line link.BuildLine
+			if json.Unmarshal(msg.Data, &line) == nil {
+				lines = append(lines, line)
+			}
+		}
+		if len(batch) < 200 {
+			return lines, nil
+		}
+	}
+}

cmd/mesh-controller/try_test.go

@@ -0,0 +1,194 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"reflect"
+	"strings"
+	"testing"
+
+	"github.com/novox/mesh-controller/internal/catalogue"
+	"github.com/novox/mesh-controller/internal/link"
+)
+
+// A branch is tried before its pull request (novox/hq issue 686): the repository's own check asked for a pushed
+// branch or commit, with no pull request.
+
+// What a try asks is a check — after deliveries in the build queue, bounded as one — of the repository's own
+// script alone: no module of the graph, so no gate; nothing built for a merge, so no reusable image.
+func TestATryAsksACheckOfTheRepositorysOwnScriptAlone(t *testing.T) {
+	request := link.BuildRequest{ID: "build-1", Ref: "c0ffee", Check: &link.CheckRequest{Owner: "novox", Repo: "a",
+		Number: 7, Base: "main", Modules: []string{"a"}, New: []string{"b"}, Manifests: []string{"module.json"},
+		Dependents: []string{"c"}, Builds: []link.CheckBuild{{Module: "a"}}, Judge: link.JudgeSelf,
+		Plan: &link.ChangePlan{}}}
+	tried := asATry(request, "^TestStore", true)
+	c := tried.Check
+	if !c.Try || c.Number != 0 || c.Tests != "^TestStore" || !c.StoreOnly {
+		t.Fatalf("not marked a try, or it kept a pull request's number: %+v", c)
+	}
+	if len(c.Modules)+len(c.New)+len(c.Manifests)+len(c.Dependents)+len(c.Builds) != 0 || c.Judge != "" || c.Plan != nil {
+		t.Fatalf("a try runs the gate or builds for a merge: %+v", c)
+	}
+	if c.Base != "main" || c.Owner != "novox" || tried.Ref != "c0ffee" {
+		t.Fatalf("a try lost what it merges into what: %+v", tried)
+	}
+	if link.KindOf(tried) != link.KindCheck {
+		t.Fatal("a try does not count as a check in the build queue")
+	}
+}
+
+// A try's outcome is heard and left there: no `checked` is said, so the forge's holder sets no status, and
+// nothing is recorded or registered (the handler holds no store here, and would fail reaching for one).
+func TestATrysOutcomeSetsNoStatusAndRegistersNothing(t *testing.T) {
+	said := &saidOnTheBus{}
+	checkEvents = said
+	defer func() { checkEvents = nil }()
+	for name, result := range map[string]link.BuildResult{
+		"a try": {ID: "build-1", Ref: "c0ffee", Checked: &link.CheckRequest{Owner: "novox", Repo: "a", Try: true},
+			Check: &link.CheckOutcome{Verdict: "pass", RepoCheck: &link.CheckLayer{Verdict: "fail", Summary: "failed"}}},
+		"a try that could not run": {ID: "build-2", Checked: &link.CheckRequest{Owner: "novox", Repo: "a", Try: true},
+			Failed: "cannot clone"},
+		// A build seat from before the mark echoes the ask without it: a check of no pull request and no
+		// group is still nobody's status.
+		"a try echoed by an older build seat": {ID: "build-3", Checked: &link.CheckRequest{Owner: "novox", Repo: "a"},
+			Check: &link.CheckOutcome{Verdict: "pass"}},
+	} {
+		if err := (builds{}).Built(context.Background(), result); err != nil {
+			t.Fatalf("%s: %v", name, err)
+		}
+	}
+	if len(said.events) != 0 {
+		t.Fatalf("a try's outcome was said for the forge: %v", said.events)
+	}
+	// A pull request's check is still said.
+	_ = (builds{}).Built(context.Background(), link.BuildResult{ID: "build-4", Checked: &link.CheckRequest{
+		Owner: "novox", Repo: "a", Number: 7}, Check: &link.CheckOutcome{Verdict: "pass"}})
+	if len(said.events) != 1 {
+		t.Fatalf("a pull request's check was said %d time(s)", len(said.events))
+	}
+}
+
+// saidOnTheBus keeps the seat events said, and nothing else.
+type saidOnTheBus struct {
+	link.Bus
+	events []string
+}
+
+func (s *saidOnTheBus) PublishSeatEvent(_ context.Context, seat, event string, _ []byte) error {
+	s.events = append(s.events, seat+" "+event)
+	return nil
+}
+
+// A ref the forge does not hold is refused before anything is asked, naming it.
+func TestATryOfAnUnknownRefIsRefusedLoudly(t *testing.T) {
+	was := forgeCommit
+	defer func() { forgeCommit = was }()
+	forgeCommit = func(_ context.Context, owner, repo, ref string) (string, string, error) {
+		return "", "", errors.New("404 object does not exist [id: " + ref + "]")
+	}
+	err := tryCommand(context.Background(), []string{"novox/mesh-controller", "fix/no-such-branch"})
+	if err == nil {
+		t.Fatal("a try of a ref the forge does not hold was asked")
+	}
+	for _, want := range []string{"fix/no-such-branch", "novox/mesh-controller", "nothing was asked", "404"} {
+		if !strings.Contains(err.Error(), want) {
+			t.Errorf("the refusal does not say %q: %v", want, err)
+		}
+	}
+	for _, args := range [][]string{{"mesh-controller", "main"}, {"novox/mesh-controller"}, {"novox/a", "--upload-pack=x"},
+		{"novox/a", "main", "--tests", "x; rm -rf /"}, {"novox/a", "main", "--id", "build-1"}} {
+		if err := tryCommand(context.Background(), args); err == nil {
+			t.Errorf("try %v was taken", args)
+		}
+	}
+}
+
+// The answer of a try carries the lines that name what failed (novox/hq issue 460's shape) and how long it took.
+func TestATrysAnswerCarriesTheFailingLines(t *testing.T) {
+	tried, _ := json.Marshal(link.Tried{Verdict: "fail", Summary: "its merge-check.sh failed: TestX", Took: "5m3s",
+		Head: "c0ffee", Trunk: "ca3f43c", Failed: []string{"--- FAIL: TestX (0.01s)", "    x_test.go:12: got 1, want 2",
+			"FAIL\tgithub.com/novox/a/cmd\t3.1s"}})
+	lines := []link.BuildLine{{Seq: 1, Step: "check", Message: "novox/a#0 at c0ffee"},
+		{Seq: 2, Step: "output", Message: "ok  	github.com/novox/a/internal	1.2s"},
+		{Seq: 3, Step: link.StepTried, Message: string(tried)}, {Seq: 4, Step: "checked", Message: "pass: x"}}
+	a := tryAnswerOf("build-1", lines)
+	if a.State != "fail" || a.Took != "5m3s" || len(a.Failed) != 3 || a.Failed[0] != "--- FAIL: TestX (0.01s)" ||
+		a.Trunk != "ca3f43c" || a.ID != "build-1" {
+		t.Fatalf("the answer lost the verdict, the time or the failing lines: %+v", a)
+	}
+	// Not answered yet: said as running, with how far it is — never as a pass.
+	if a := tryAnswerOf("build-1", lines[:2]); a.State != "running" || a.Last == "" {
+		t.Fatalf("a try still running: %+v", a)
+	}
+	if a := tryAnswerOf("build-1", nil); a.State != "waiting" {
+		t.Fatalf("a try nothing was said of: %+v", a)
+	}
+	// One that could not run is an error with the build seat's word, never a pass.
+	if a := tryAnswerOf("build-1", append(lines[:1:1], link.BuildLine{Seq: 2, Step: "failed",
+		Message: "cannot clone"})); a.State != "error" || !strings.Contains(a.Said, "cannot clone") {
+		t.Fatalf("a try that could not run: %+v", a)
+	}
+}
+
+// One try of a commit at a time, and four in all (novox/hq issue 686): a second ask is answered the first's id,
+// a fifth is refused; a try that ended, and a pull request's check, count for nothing.
+func TestTriesAreBoundedInNumber(t *testing.T) {
+	ask := func(id, repo, ref, state string, try bool) link.QueuedAsk {
+		return link.QueuedAsk{ID: id, State: state, Request: link.BuildRequest{ID: id, Ref: ref,
+			Check: &link.CheckRequest{Owner: "novox", Repo: repo, Try: try}}}
+	}
+	q := link.Queue{Asks: []link.QueuedAsk{
+		ask("t1", "a", "c1", link.AskInFlight, true), ask("t2", "a", "c2", link.AskWaiting, true),
+		ask("t3", "b", "c1", link.AskDead, true), ask("p1", "a", "c9", link.AskWaiting, false)}}
+	if same, room := triesIn(q, "novox", "a", "c2"); same != "t2" || !room {
+		t.Fatalf("a second try of a commit: %q %v", same, room)
+	}
+	if same, room := triesIn(q, "novox", "b", "c1"); same != "" || !room {
+		t.Fatalf("a dead try, or another repository's, was taken for this one: %q %v", same, room)
+	}
+	if same, _ := triesIn(q, "novox", "a", "c9"); same != "" {
+		t.Fatalf("a pull request's check was taken for a try: %q", same)
+	}
+	q.Asks = append(q.Asks, ask("t4", "c", "c3", link.AskWaiting, true), ask("t5", "d", "c4", link.AskWaiting, true))
+	if _, room := triesIn(q, "novox", "e", "c5"); room {
+		t.Fatal("a fifth try was let in")
+	}
+	// An id is checked before it is a token of a bus subject.
+	for _, id := range []string{"x.>", "*", "a b"} {
+		if err := tryCommand(context.Background(), []string{"--id", id}); err == nil ||
+			!strings.Contains(err.Error(), "not a try's id") {
+			t.Errorf("try --id %q: %v", id, err)
+		}
+	}
+}
+
+// The verb runs its command, and is declared with the shell habit it replaces (novox/hq ADR 0245).
+func TestTheTryVerbRunsItsCommand(t *testing.T) {
+	for _, c := range []struct {
+		args map[string]any
+		want []string
+	}{
+		{map[string]any{"repository": "novox/a", "ref": "fix/x"}, []string{"try", "novox/a", "fix/x"}},
+		{map[string]any{"repository": "novox/a", "ref": "fix/x", "base": "main", "tests": "^TestX$", "store-only": "true"},
+			[]string{"try", "novox/a", "fix/x", "--base", "main", "--tests", "^TestX$", "--store-only"}},
+		{map[string]any{"id": "build-1"}, []string{"try", "--id", "build-1"}},
+	} {
+		got, err := argvFor("try", c.args)
+		if err != nil || !reflect.DeepEqual(got, c.want) {
+			t.Errorf("try %v: %v %v, want %v", c.args, got, err, c.want)
+		}
+	}
+	if _, err := argvFor("try", map[string]any{"repository": "novox/a"}); err == nil {
+		t.Error("a try of no ref was taken")
+	}
+	for _, v := range catalogue.ControllerVerbs {
+		if v.Name == "try" {
+			if len(v.Replaces) == 0 {
+				t.Error("try names no shell habit it replaces")
+			}
+			return
+		}
+	}
+	t.Error("try is not a verb of the controller seat")
+}

cmd/mesh-controller/upgrades.go

@@ -79,7 +79,7 @@ func (f following) Upgraded(ctx context.Context, u link.Upgraded) error {
 	// `rebuild`, a `replay` registered — was sent here one machine after another without any judging; it
 	// now waits for a gate like any other build, and the release plan walks it through the machines, one
 	// at a time, each judged.
-	fmt.Printf("%s moved to %s outside a plan; a release plan sends it to %s, one machine at a time, each judged "+
+	fmt.Printf("%s moved to %s outside a plan; a release plan sends it to %s, one machine first and then the rest at once, each judged "+
 		"(`upgrade backlog` lists what waits)\n", u.Module, shortCommit(u.Commit), readableList(on))
 	return nil
 }

cmd/mesh-controller/urgent_unhealthy_test.go

@@ -0,0 +1,91 @@
+package main
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/novox/mesh-controller/internal/catalogue"
+	"github.com/novox/mesh-controller/internal/conditions"
+	"github.com/novox/mesh-controller/internal/inventory"
+	"github.com/novox/mesh-controller/internal/link"
+)
+
+// A module may declare its unhealthy urgent (novox/hq ADR 0355): its module-unhealthy condition is then raised
+// urgent; without the field it stays a warning; a wait for a new login stays a warning whatever the module says.
+
+// judgedTwice judges one machine's statement twice, over a catalogue in which mail declares its unhealthy
+// urgent and notes says nothing, and returns what is open.
+func judgedTwice(t *testing.T, unhealthy map[string][]inventory.ResourceHealth) []conditions.Condition {
+	t.Helper()
+	ctx := t.Context()
+	k, _ := withConditionsInMemory(t)
+	was := readHoldingFor
+	t.Cleanup(func() { readHoldingFor = was })
+	readHoldingFor = func(_ context.Context, _ *inventory.Inventory, open []conditions.Condition) (*holding, error) {
+		return &holding{ctx: context.Background(), open: open, providers: map[string]providerLookup{},
+			shelf: map[string]catalogue.Manifest{
+				"mail": {Module: "mail", Version: "1", Unhealthy: &catalogue.UnhealthyPolicy{
+					Severity: catalogue.UnhealthyUrgent, Why: "mail is refused or stuck for everyone with a mailbox"}},
+				"notes": {Module: "notes", Version: "1"},
+			}}, nil
+	}
+	streaks := map[string]int{}
+	for look := 1; look <= 2; look++ {
+		for m := range unhealthy {
+			streaks[m] = look
+		}
+		if err := judgeModuleHealth(ctx, nil, k, "anchor", unhealthy, streaks, time.Now()); err != nil {
+			t.Fatal(err)
+		}
+	}
+	open, err := k.Open(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return open
+}
+
+func containerDown(module string) inventory.ResourceHealth {
+	return inventory.ResourceHealth{Module: module, Resource: module + ".web", Kind: "container", Target: module,
+		State: link.StateUnhealthy, Reason: "down"}
+}
+
+func TestAModuleThatDeclaresItsUnhealthyUrgentIsRaisedUrgent(t *testing.T) {
+	open := judgedTwice(t, map[string][]inventory.ResourceHealth{"mail": {containerDown("mail")}})
+	c := conditionOf(open, "module.mail.anchor.unhealthy")
+	if c == nil {
+		t.Fatalf("mail's unhealthy condition was not raised: %+v", open)
+	}
+	if c.Severity != conditions.Urgent {
+		t.Errorf("mail declares its unhealthy urgent, and it was raised %s", c.Severity)
+	}
+}
+
+func TestAModuleThatSaysNothingOfItsUnhealthyStaysAWarning(t *testing.T) {
+	open := judgedTwice(t, map[string][]inventory.ResourceHealth{"notes": {containerDown("notes")}})
+	c := conditionOf(open, "module.notes.anchor.unhealthy")
+	if c == nil {
+		t.Fatalf("notes' unhealthy condition was not raised: %+v", open)
+	}
+	if c.Severity != conditions.Warning {
+		t.Errorf("notes says nothing of its unhealthy, and it was raised %s", c.Severity)
+	}
+}
+
+// Only the module-unhealthy condition changes (ADR 0355 §4): a wait for a new login (ADR 0254) of a module that
+// declares its unhealthy urgent stays a warning.
+func TestAWaitForANewLoginStaysAWarningWhenTheModuleDeclaresItsUnhealthyUrgent(t *testing.T) {
+	open := judgedTwice(t, map[string][]inventory.ResourceHealth{"mail": {relogin("mail", "operator"),
+		userUnit("mail", "operator")}})
+	c := conditionOf(open, "module.mail.anchor.relogin-needed")
+	if c == nil {
+		t.Fatalf("mail's relogin-needed condition was not raised: %+v", open)
+	}
+	if c.Severity != conditions.Warning {
+		t.Errorf("a wait for a new login was raised %s; want a warning", c.Severity)
+	}
+	if conditionOf(open, "module.mail.anchor.unhealthy") != nil {
+		t.Errorf("a wait for a new login raised mail's unhealthy condition beside it: %+v", open)
+	}
+}

cmd/mesh-controller/walk_said.go

@@ -177,6 +177,12 @@ func walkReached(p inventory.Plan, running func(string) []string) map[string][]s
 			reached = appendNew(reached, r.Gate.Machines...)
 			carried(r.Gate)
 		}
+		for _, g := range r.Gates {
+			if g != nil && !g.Pending {
+				reached = appendNew(reached, g.Machines...)
+				carried(g)
+			}
+		}
 		for _, tier := range p.Tiers {
 			for _, m := range tier {
 				for _, n := range running(m) {

cmd/mesh-controller/watchdogs.go

@@ -92,6 +92,8 @@ type signalFacts struct {
 	// consumers: the condition counts the messages given up on, not the looks (novox/hq issue 440).
 	deadLettersNewest map[string]time.Time
 	advisoriesErr     error
+	// busFaultsErr is why the bus module's events could not be read this tick (novox/hq ADR 0357).
+	busFaultsErr error
 
 	selfCheck selfCheckFacts
 
@@ -358,6 +360,15 @@ func (w *watchdogs) gather(ctx context.Context) *signalFacts {
 	}
 	f.advisories = link.Advisories.Since(now.Add(-advisoryQuiet))
 	f.lostConsumers, f.advisoriesErr = w.lostConsumers(ctx, f.advisories)
+	// And what the bus did to every other user's connection, as the bus module said it (novox/hq ADR 0357):
+	// read back for the same hour, and one advisory with the controller's own where both are its.
+	// A read that fails is its own condition, never S9 blind: the controller's own signals are still said.
+	if w.server != nil && w.js != nil {
+		var faults []link.Advisory
+		if faults, f.busFaultsErr = w.server.BusFaults(ctx, now.Add(-advisoryQuiet)); f.busFaultsErr == nil {
+			f.advisories = link.MergeAdvisories(f.advisories, faults)
+		}
+	}
 	if f.advisoriesErr == nil && w.js != nil {
 		f.deadLetters, f.advisoriesErr = link.HeldDeadLetters(w.js.Context())
 	}

internal/broker/bus_module_emits_test.go

@@ -0,0 +1,34 @@
+package broker
+
+import (
+	"slices"
+	"testing"
+)
+
+// **The bus module's watch speaks through the runtime that carries it** (novox/hq ADR 0357): the node's
+// runtime is granted the events the bus module declares, under the module's name, while the bus's own
+// account keeps the snapshot API and nothing else (ADR 0235).
+func TestTheRuntimeCarryingTheBusModuleMayPublishItsEventsAndTheBussAccountMayNot(t *testing.T) {
+	events := []string{"bus.slow-consumer", "bus.connection-closed"}
+	runtime := Principal{Kind: KindNodeTools, Node: "anchor", Module: RuntimeModule,
+		Carries: []Declared{{Module: "nats", Emits: events}}}
+	p, err := PermissionsFor(runtime)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, e := range events {
+		if !slices.Contains(p.Publish, "mesh.mod.nats.event."+e) {
+			t.Errorf("the runtime carrying the bus module may not publish %s: %v", e, p.Publish)
+		}
+	}
+	account := Principal{Kind: KindModule, Node: "anchor", Module: "nats", Emits: events, SnapshotsTheBus: true}
+	a, err := PermissionsFor(account)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, s := range a.Publish {
+		if s == "mesh.mod.nats.event.bus.slow-consumer" || s == "mesh.mod.nats.event.bus.connection-closed" {
+			t.Errorf("the bus's own account is granted %s", s)
+		}
+	}
+}

internal/builder/builder.go

@@ -162,6 +162,10 @@ type Reuse struct {
 	// keyFirst is a check's build (§1): its key is taken before anything is built, and a module with none is not
 	// built at all — nothing could ever take it.
 	keyFirst bool
+	// pull and head are the check's own pull request and the head it judged (novox/hq issue 703): it keeps only a
+	// build an earlier check of the same pull request at the same head made.
+	pull PullRef
+	head string
 }
 
 // errNoKey is a check's build of a module whose source does not pin it: not built (ADR 0350 §1).
@@ -374,7 +378,7 @@ func build(ctx context.Context, run Runner, publish Publisher,
 		// only when asked — a check, a dry run, `build --ref` and `rebuild` never are. Its key is taken by the same
 		// steps a build takes, stopped before anything is built; what it takes is copied by digest.
 		if reuse != nil && reuse.keyFirst {
-			_, key, err := keyFor(ctx, run, publish, manifest, within, workspace, commit, credentials, artifacts, args,
+			keyed, key, err := keyFor(ctx, run, publish, manifest, within, workspace, commit, credentials, artifacts, args,
 				held, npmrcPath, npmrc, seatBases, src, say)
 			if err == nil && key.Key == "" {
 				err = fmt.Errorf("%w: %s", errNoKey, key.Why)
@@ -383,6 +387,11 @@ func build(ctx context.Context, run Runner, publish Publisher,
 				say("reuse", "not built for the merge: %v", err)
 				return Result{Commit: commit, NoKey: err.Error()}, err
 			}
+			// **A check keeps a build of the same key a verdict names** (novox/hq issue 703): asked again when only
+			// the trunk moved, it builds nothing the earlier check built of an unchanged source.
+			if kept := keptCheckBuild(ctx, *reuse, manifest.Module, key.Key, len(artifacts), say); kept != nil {
+				built, src, reused = kept.Made, keyed, kept
+			}
 		} else if reuse != nil && reuse.Scratch != nil {
 			taken, keyed, why := takeACheckBuild(ctx, run, publish, *reuse, manifest, within, workspace, commit,
 				credentials, artifacts, args, held, npmrcPath, npmrc, seatBases, src, onTrunk, say)
@@ -492,6 +501,47 @@ func takeACheckBuild(ctx context.Context, run Runner, publish Publisher, reuse R
 	return taken, keyed, ""
 }
 
+// keptCheckBuild is the build a check keeps instead of building (novox/hq issue 703): the one kept under the
+// module's key by an earlier check of the same pull request at the same head — only the trunk moved — when a verdict
+// of the build seat names its key and every digest — the record alone is never trusted (ADR 0350 §2) — and it holds
+// every artifact the module declares. Another pull request's build, or an earlier head's, is never kept. Nil, and
+// the check builds, otherwise.
+func keptCheckBuild(ctx context.Context, reuse Reuse, module, key string, artifacts int,
+	say func(step, format string, args ...any)) *Reused {
+	if reuse.Scratch == nil || reuse.head == "" {
+		return nil
+	}
+	var same []NamedBuild
+	for _, n := range reuse.Named {
+		if n.Pull == reuse.pull {
+			same = append(same, n)
+		}
+	}
+	if len(same) == 0 {
+		return nil
+	}
+	found, ok, err := reuse.Scratch.Find(ctx, module, key)
+	switch {
+	case err != nil:
+		say("reuse", "the scratch namespace could not be read, so the check builds: %v", err)
+		return nil
+	case !ok:
+		return nil
+	case found.Pull != reuse.pull || found.Head == "" || twelve(found.Head) != twelve(reuse.head):
+		say("reuse", "the build kept under %s is %s, not this pull request's at this head: built", twelve(key[3:]),
+			found.Said())
+		return nil
+	case unnamed(same, module, key, found) != "":
+		say("reuse", "a build is kept under %s and no verdict names it with its digests: built", twelve(key[3:]))
+		return nil
+	case len(found.Made) != artifacts:
+		return nil
+	}
+	kept := &Reused{From: found, Made: found.Made}
+	say("reuse", "kept, not built: %s", strings.Replace(kept.Words(), "reused from", "the build of", 1))
+	return kept
+}
+
 // keyFor takes a build's reuse key by the steps a build takes, each artifact stopped before anything is built or
 // published (ADR 0350 §2): its own copy of the source inputs, so the build's are untouched.
 func keyFor(ctx context.Context, run Runner, publish Publisher, manifest catalogue.Manifest,
@@ -1076,6 +1126,16 @@ func one(ctx context.Context, run Runner, publish Publisher,
 			return catalogue.Built{}, fmt.Errorf("%s: building %s failed: %w", module, a.Name, err)
 		}
 		say("image", "built, publishing")
+		// Its bases linked into its repository first, so the push needs none of their blobs from this
+		// machine's store, which may not hold them (novox/hq issue 694). Said and not fatal: a push
+		// from a store that holds them works without, and one that fails says which blob it lacked.
+		if lender, can := publish.(BaseLender); can {
+			if n, err := lender.LendBases(ctx, module+"/"+a.Name, buildArgValues(args)); err != nil {
+				say("image", "its bases could not all be linked into %s/%s before the push: %v", module, a.Name, err)
+			} else if n > 0 {
+				say("image", "%d blob(s) of its bases linked into %s/%s before the push", n, module, a.Name)
+			}
+		}
 		reference, err := publish.PublishImage(ctx, local, module+"/"+a.Name)
 		if err != nil {
 			return catalogue.Built{}, err
@@ -1427,6 +1487,19 @@ func standingOn(ctx context.Context, manifest catalogue.Manifest, held map[strin
 	return args, resolved, nil
 }
 
+// buildArgValues is what each --build-arg of a build was handed: the bases, as this mesh holds them.
+func buildArgValues(args []string) []string {
+	var values []string
+	for i := 0; i+1 < len(args); i += 2 {
+		if args[i] == "--build-arg" {
+			if _, value, has := strings.Cut(args[i+1], "="); has {
+				values = append(values, value)
+			}
+		}
+	}
+	return values
+}
+
 // compile runs a module's own code through its toolchain, and says where the result is.
 //
 // **In the module's own directory, under the path the toolchain expects.** A module is compiled

internal/builder/check.go

@@ -103,6 +103,23 @@ type CheckSpec struct {
 	// for the walk to take. None for a group's composed check, whose members' own checks build.
 	Builds    []CheckBuildSpec
 	BuildWith *CheckBuilding
+	// Tests and StoreOnly narrow what the repository's own script runs, for a branch tried before its pull
+	// request (novox/hq issue 686): handed to the script as EnvTests and EnvStoreOnly, which it may read.
+	Tests     string
+	StoreOnly bool
+}
+
+// selection is what a check hands the repository's script to narrow what it runs (novox/hq issue 686): nothing
+// for a pull request's check, which always runs whole.
+func selection(spec CheckSpec) []string {
+	var env []string
+	if spec.Tests != "" {
+		env = append(env, EnvTests+"="+spec.Tests)
+	}
+	if spec.StoreOnly {
+		env = append(env, EnvStoreOnly+"=1")
+	}
+	return env
 }
 
 // GroupHead is one other head of a delivery group's composed check.
@@ -193,6 +210,11 @@ const (
 	// EnvGroup is a delivery group's other heads, as JSON, for the gate (novox/hq ADR 0239); empty for a
 	// pull request checked alone.
 	EnvGroup = "MESH_CHECK_GROUP"
+	// EnvTests is a `go test -run` pattern and EnvStoreOnly is 1 when a branch tried before its pull request
+	// asks for only those tests, or only the store tests (novox/hq issue 686). Never set for a pull request's
+	// check. A script that reads neither runs whole.
+	EnvTests     = "MESH_CHECK_TESTS"
+	EnvStoreOnly = "MESH_CHECK_STORE_ONLY"
 )
 
 // CheckTimeout bounds one check; a check that runs past it is an error, not a pass.
@@ -332,6 +354,22 @@ func Check(ctx context.Context, run Runner, spec CheckSpec, workspace, registry
 		v.Head, v.Trunk, v.Merge, v.Beside, v.Members = judged.Head, judged.Trunk, judged.Merge, judged.Beside, judged.Members
 		return v
 	}
+	// **What the merge would move is built from a checkout nothing of the check touches** (novox/hq issue 703): the
+	// gate and the repository's own check run in containers that mount the workspace read-write, so they can change
+	// its tree, its objects and its caches. The builds are made from a copy of the merge's objects, cloned before
+	// anything of the change runs, outside the workspace — so what is kept under a key is what the key describes.
+	building, buildingTree := "", ""
+	if len(spec.Builds) > 0 && spec.BuildWith != nil && len(spec.Group) == 0 {
+		at := judged.Merge
+		if at == "" {
+			at = spec.Ref
+		}
+		building, buildingTree, err = checkoutForTheBuilds(ctx, run, tree, at, workspace)
+		if err != nil {
+			return CheckVerdict{}, err
+		}
+		defer os.RemoveAll(building)
+	}
 	// **The base branch's check judges the change** (novox/hq issue 310), never the one the change brings.
 	judging, err := TheCheckThatJudges(ctx, tree, spec.Base)
 	if err != nil {
@@ -515,6 +553,7 @@ func Check(ctx context.Context, run Runner, spec CheckSpec, workspace, registry
 		EnvModules + "=" + strings.Join(append(append([]string{}, spec.Modules...), spec.New...), ","),
 		EnvGroup + "=" + groupFile,
 		"GOCACHE=" + filepath.Join(workspace, "go-cache"), "GOMODCACHE=" + filepath.Join(workspace, "go-modules")}
+	env = append(env, selection(spec)...)
 
 	v := CheckVerdict{}
 	modules := append(append([]string{}, spec.Modules...), prefixed("new:", spec.New)...)
@@ -587,7 +626,7 @@ func Check(ctx context.Context, run Runner, spec CheckSpec, workspace, registry
 			say("check", "%s", why)
 		} else {
 			began := time.Now()
-			v.Built = buildForTheMerge(ctx, run, spec, *spec.BuildWith, workspace, tree, judged.Merge, judged, forge,
+			v.Built = buildForTheMerge(ctx, run, spec, *spec.BuildWith, building, buildingTree, judged.Merge, judged, forge,
 				func(step, message string) {
 					if log != nil {
 						log(step, redact.redact(message))
@@ -600,6 +639,39 @@ func Check(ctx context.Context, run Runner, spec CheckSpec, workspace, registry
 	return named(v), nil
 }
 
+// checkoutForTheBuilds is a clone of the commit a check builds for its merge, made before anything of the check runs,
+// outside the workspace its containers mount (novox/hq issue 703): the directory to remove, and the clone in it.
+// Cloned over git's own transport, never by linking the objects: what the check's containers later write into the
+// workspace's objects cannot reach it.
+func checkoutForTheBuilds(ctx context.Context, run Runner, tree, at, workspace string) (string, string, error) {
+	dir, err := os.MkdirTemp("", "mesh-check-builds-")
+	if err != nil {
+		return "", "", err
+	}
+	if withinDir(workspace, dir) {
+		os.RemoveAll(dir)
+		return "", "", fmt.Errorf("the temporary directory %s is inside the workspace %s, which a check's containers "+
+			"mount: the merge is not built from where its tests could change it", dir, workspace)
+	}
+	commit, err := run(ctx, tree, "git", "rev-parse", "--verify", at+"^{commit}")
+	if err != nil {
+		os.RemoveAll(dir)
+		return "", "", fmt.Errorf("the commit to build for the merge, %s: %w", at, err)
+	}
+	commit = strings.TrimSpace(commit)
+	if _, err := run(ctx, tree, "git", "update-ref", "refs/heads/mesh-check-builds", commit); err != nil {
+		os.RemoveAll(dir)
+		return "", "", err
+	}
+	cloned := filepath.Join(dir, "merged")
+	if _, err := run(ctx, dir, "git", "clone", "--quiet", "--no-local", "--no-checkout", "--branch",
+		"mesh-check-builds", tree, cloned); err != nil {
+		os.RemoveAll(dir)
+		return "", "", fmt.Errorf("cannot copy the merge to build it: %w", err)
+	}
+	return dir, cloned, nil
+}
+
 // builtCount is how many of a check's builds for its merge were built.
 func builtCount(built []CheckBuilt) int {
 	n := 0

internal/builder/check_builds.go

@@ -37,6 +37,11 @@ type CheckBuilding struct {
 	Held    map[string]string
 	Npmrc   Npmrc
 	Seats   map[string]string
+	// Named are the builds the build seat's verdicts of earlier checks of this pull request at this head name
+	// (novox/hq issue 703): a build kept under a module's key is kept again, instead of built, only when one of them
+	// names its key and every digest, and the build is this pull request's at this head. The record alone is never
+	// enough.
+	Named []NamedBuild
 }
 
 // CheckBuilt is one module a check built for its merge, as its verdict lists it (§1): its key and its artifacts, or
@@ -48,6 +53,9 @@ type CheckBuilt struct {
 	// NotBuilt says why it was not: no key, a build that failed, or a module after one of those.
 	NotBuilt string
 	Took     time.Duration
+	// Kept is the check whose build this check kept instead of building, its key unchanged (novox/hq issue 703):
+	// the verdict names that build, by key and digest, as that check's. Empty when this check built it.
+	Kept string
 }
 
 // skipsTheBuilds is why a check builds nothing for its merge; empty when it builds.
@@ -100,8 +108,9 @@ func buildForTheMerge(ctx context.Context, run Runner, spec CheckSpec, with Chec
 		say("build", "for the merge: %s (tier %d)", b.Module, b.Tier)
 		var mirrored []string
 		result, err := build(ctx, run, scratchPublisher{to: with.Publish}, repository, b.Path, at,
-			filepath.Join(workspace, "for-the-merge"), held, with.Npmrc, forge, log, &mirrored, &Reuse{keyFirst: true},
+			filepath.Join(workspace, "for-the-merge"), held, with.Npmrc, forge, log, &mirrored,
-			with.Seats)
+			&Reuse{keyFirst: true, Scratch: with.Scratch, Named: with.Named,
+				pull: PullRef{Owner: spec.Owner, Repo: spec.Repo, Number: spec.Number}, head: judged.Head}, with.Seats)
 		built := CheckBuilt{Module: b.Module, Key: result.ReuseKey, Took: time.Since(began)}
 		switch {
 		case errors.Is(err, errNoKey):
@@ -123,6 +132,17 @@ func buildForTheMerge(ctx context.Context, run Runner, spec CheckSpec, with Chec
 		for _, m := range result.Built {
 			held[b.Module+"/"+m.Name] = m.Reference
 		}
+		if result.Reused != nil {
+			// **Kept, not built** (novox/hq issue 703): the earlier check's build, named as that check's, so the
+			// walk takes it as the verdict names it; this check's document names it too, so it stays while this
+			// check does (ADR 0350 §5).
+			built.Kept = result.Reused.From.Check
+			say("build", "%s kept for the merge under %s: %s", b.Module, twelve(result.ReuseKey[3:]),
+				result.Reused.From.Said())
+			out = append(out, built)
+			kept = append(kept, result.Reused.From)
+			continue
+		}
 		say("build", "%s built for the merge under %s (%s)", b.Module, twelve(result.ReuseKey[3:]), built.Took.Round(time.Second))
 		out = append(out, built)
 		if len(result.Built) > 0 {

internal/builder/check_merge_test.go

@@ -210,3 +210,53 @@ func TestACheckMergeRunsNoHook(t *testing.T) {
 		t.Fatalf("a hook ran when the check made its merge: %s", said)
 	}
 }
+
+// What a check's tests change in the workspace never reaches what it builds for the merge (novox/hq issue 703): the
+// builds are made from a copy of the merge, outside the workspace, cloned before anything of the change runs.
+func TestWhatTheTestsChangeInTheWorkspaceNeverReachesTheBuild(t *testing.T) {
+	repo, head, _ := aTrunkAndABranch(t, map[string]string{"main.go": "package main // the merge\n"},
+		map[string]string{"trunk-only": "t"}, map[string]string{"head-only": "h"})
+	workspace := t.TempDir()
+	tree := filepath.Join(workspace, "check", "checked")
+	if out, err := exec.Command("git", "clone", "--quiet", repo, tree).CombinedOutput(); err != nil {
+		t.Fatalf("%v\n%s", err, out)
+	}
+	dir, cloned, err := checkoutForTheBuilds(t.Context(), Command, tree, head, workspace)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(dir)
+	if withinDir(workspace, cloned) {
+		t.Fatalf("the builds' checkout %s is inside the workspace %s the tests mount", cloned, workspace)
+	}
+
+	// The tests rewrite the tree, its branch and every object it holds.
+	if err := os.WriteFile(filepath.Join(tree, "main.go"), []byte("package main // planted\n"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := filepath.WalkDir(filepath.Join(tree, ".git", "objects"), func(path string, d os.DirEntry, err error) error {
+		if err != nil || d.IsDir() {
+			return err
+		}
+		_ = os.Chmod(path, 0o644)
+		return os.WriteFile(path, []byte("planted"), 0o644)
+	}); err != nil {
+		t.Fatal(err)
+	}
+
+	// The build clones the merge from its own checkout, as buildForTheMerge does, and reads what the merge holds.
+	build := filepath.Join(t.TempDir(), "source")
+	if out, err := exec.Command("git", "clone", "--quiet", cloned, build).CombinedOutput(); err != nil {
+		t.Fatalf("%v\n%s", err, out)
+	}
+	if out, err := exec.Command("git", "-C", build, "checkout", "--quiet", head).CombinedOutput(); err != nil {
+		t.Fatalf("%v\n%s", err, out)
+	}
+	body, err := os.ReadFile(filepath.Join(build, "main.go"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(body) != "package main // the merge\n" {
+		t.Fatalf("the build read %q: what the tests wrote reached it", body)
+	}
+}

internal/builder/check_test.go

@@ -590,3 +590,15 @@ func TestARepositoryInTwoLanguagesIsCheckedInBoth(t *testing.T) {
 		t.Errorf("a part in a toolchain the mesh does not hold answered %+v — never a pass", layer)
 	}
 }
+
+// A branch tried before its pull request may narrow what the repository's script runs (novox/hq issue 686); a
+// pull request's check is handed nothing, and runs whole.
+func TestOnlyATrysSelectionReachesTheScript(t *testing.T) {
+	if env := selection(CheckSpec{Number: 7}); len(env) != 0 {
+		t.Fatalf("a pull request's check was handed a selection: %v", env)
+	}
+	env := selection(CheckSpec{Tests: "^TestX$", StoreOnly: true})
+	if len(env) != 2 || env[0] != "MESH_CHECK_TESTS=^TestX$" || env[1] != "MESH_CHECK_STORE_ONLY=1" {
+		t.Fatalf("a try's selection: %v", env)
+	}
+}

internal/builder/lend.go

@@ -0,0 +1,178 @@
+package builder
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"runtime"
+	"strings"
+)
+
+// **A built image's bases are linked into its repository before it is pushed** (novox/hq issue 694).
+//
+// A push reads every blob of the image out of this machine's store, unless the repository it goes to
+// already holds that blob: the runtime asks the registry first, blob by blob, and reads locally only
+// what the registry lacks. A runtime keeping its images in containerd's store — the default for a
+// fresh install from docker 29 on — does not always hold the compressed layers of the base an image
+// was built FROM: a layer whose unpacked form it already had is never fetched. The push of such an
+// image then fails on a layer this machine never had ("not all of them are available locally"), while
+// the very bytes sit in this registry, under the repository the base was mirrored into.
+//
+// So the base's blobs are mounted into the image's repository first. A mount moves no bytes, and once
+// the repository holds a blob the push asks this machine for nothing of it — whichever store the
+// runtime keeps. A runtime that holds every layer (the classic store) is not changed by this: its push
+// finds the same blobs already there.
+
+// BaseLender links what a build's bases hold into the repository its image is about to be pushed to.
+type BaseLender interface {
+	// LendBases mounts every blob of each base this registry holds — for the platform this machine
+	// builds — into `repository`, and answers how many it mounted.
+	LendBases(ctx context.Context, repository string, bases []string) (int, error)
+}
+
+// platformed is an index's entry: a manifest and the platform it is for.
+type platformed struct {
+	descriptor
+	Platform *struct {
+		OS           string `json:"os"`
+		Architecture string `json:"architecture"`
+	} `json:"platform"`
+}
+
+// LendBases mounts each base's blobs into the repository. A base this registry does not hold under its
+// repository — named by tag, or held somewhere else — lends nothing and is no error: the push reads it
+// from this machine's store as before.
+func (r Registry) LendBases(ctx context.Context, repository string, bases []string) (int, error) {
+	mounted := 0
+	for _, base := range bases {
+		name, digest, pinned := strings.Cut(base, "@")
+		if !pinned || !strings.HasPrefix(digest, "sha256:") {
+			continue
+		}
+		where, err := parseReference(name + "@" + digest)
+		if err != nil {
+			continue
+		}
+		from := where.repository
+		if from == repository {
+			continue
+		}
+		blobs, held, err := r.blobsOf(ctx, from, digest)
+		if err != nil {
+			return mounted, fmt.Errorf("reading %s: %w", base, err)
+		}
+		if !held {
+			continue
+		}
+		for _, blob := range blobs {
+			did, err := r.mount(ctx, repository, from, blob)
+			if err != nil {
+				return mounted, fmt.Errorf("linking %s of %s into %s: %w", blob, base, repository, err)
+			}
+			if did {
+				mounted++
+			}
+		}
+	}
+	return mounted, nil
+}
+
+// blobsOf is the config and layers of the manifest under repository@digest — for an index, of each
+// manifest it names for this machine's platform. False when the registry holds no such manifest there.
+func (r Registry) blobsOf(ctx context.Context, repository, digest string) ([]string, bool, error) {
+	body, held, err := r.manifest(ctx, repository, digest)
+	if err != nil || !held {
+		return nil, held, err
+	}
+	var document struct {
+		Manifests []platformed `json:"manifests"`
+		Config    *descriptor  `json:"config"`
+		Layers    []descriptor `json:"layers"`
+	}
+	if err := json.Unmarshal(body, &document); err != nil {
+		return nil, false, fmt.Errorf("%s@%s is not a manifest: %w", repository, digest, err)
+	}
+	var blobs []string
+	if document.Config != nil {
+		blobs = append(blobs, document.Config.Digest)
+	}
+	for _, l := range document.Layers {
+		blobs = append(blobs, l.Digest)
+	}
+	for _, m := range document.Manifests {
+		if m.Platform == nil || m.Platform.OS != runtime.GOOS || m.Platform.Architecture != runtime.GOARCH {
+			continue
+		}
+		more, held, err := r.blobsOf(ctx, repository, m.Digest)
+		if err != nil {
+			return nil, false, err
+		}
+		if held {
+			blobs = append(blobs, more...)
+		}
+	}
+	return blobs, true, nil
+}
+
+// manifest reads one manifest document from this registry; false when it is not there.
+func (r Registry) manifest(ctx context.Context, repository, digest string) ([]byte, bool, error) {
+	request, err := http.NewRequestWithContext(ctx, http.MethodGet,
+		"http://"+r.Address+"/v2/"+repository+"/manifests/"+digest, nil)
+	if err != nil {
+		return nil, false, err
+	}
+	request.Header.Set("Accept", manifestAccept)
+	response, err := r.client().Do(request)
+	if err != nil {
+		return nil, false, fmt.Errorf("cannot reach the registry at %s: %w", r.Address, err)
+	}
+	defer response.Body.Close()
+	if response.StatusCode == http.StatusNotFound {
+		return nil, false, nil
+	}
+	if response.StatusCode != http.StatusOK {
+		return nil, false, fmt.Errorf("%s/%s@%s: %s", r.Address, repository, digest, response.Status)
+	}
+	body, err := io.ReadAll(io.LimitReader(response.Body, 4<<20))
+	return body, err == nil, err
+}
+
+// mount links one blob from one repository into another; false when the repository already held it.
+func (r Registry) mount(ctx context.Context, repository, from, digest string) (bool, error) {
+	base := "http://" + r.Address + "/v2/" + repository
+	if there, err := r.has(ctx, base+"/blobs/"+digest); err != nil {
+		return false, err
+	} else if there {
+		return false, nil
+	}
+	start, err := http.NewRequestWithContext(ctx, http.MethodPost,
+		base+"/blobs/uploads/?mount="+digest+"&from="+from, nil)
+	if err != nil {
+		return false, err
+	}
+	begun, err := r.client().Do(start)
+	if err != nil {
+		return false, fmt.Errorf("cannot reach the registry at %s: %w", r.Address, err)
+	}
+	begun.Body.Close()
+	if begun.StatusCode == http.StatusCreated {
+		return true, nil
+	}
+	if begun.StatusCode == http.StatusAccepted {
+		// Not mounted, and an upload begun in its place: let go of it, so nothing is left half-open.
+		if location := begun.Header.Get("Location"); location != "" {
+			if strings.HasPrefix(location, "/") {
+				location = "http://" + r.Address + location
+			}
+			if cancel, err := http.NewRequestWithContext(ctx, http.MethodDelete, location, nil); err == nil {
+				if done, err := r.client().Do(cancel); err == nil {
+					done.Body.Close()
+				}
+			}
+		}
+		return false, fmt.Errorf("%s did not mount it from %s", r.Address, from)
+	}
+	return false, fmt.Errorf("%s answered %s when asked to mount it from %s", r.Address, begun.Status, from)
+}

internal/builder/lend_test.go

@@ -0,0 +1,140 @@
+package builder
+
+import (
+	"context"
+	"encoding/json"
+	"net/http/httptest"
+	"runtime"
+	"strings"
+	"testing"
+)
+
+// A built image's bases are linked into its repository before it is pushed (novox/hq issue 694): a
+// runtime keeping containerd's image store may not hold a base layer it never had to fetch, and its push
+// asks this machine only for what the repository lacks.
+
+// aBaseForThisMachine puts an index into the registry under `repository`: one manifest for this
+// machine's platform, one for another, and answers the index's digest and each manifest's blobs.
+func aBaseForThisMachine(t *testing.T, dst *aRegistryOfRepositories, repository string) (string, []string, []string) {
+	t.Helper()
+	put := func(arch string) (string, []string) {
+		config := []byte(`{"architecture":"` + arch + `"}`)
+		layer := []byte(arch + " layer bytes")
+		for _, b := range [][]byte{config, layer} {
+			dst.blobs[digestOf(b)] = b
+			dst.link(repository, digestOf(b))
+		}
+		m, _ := json.Marshal(map[string]any{
+			"schemaVersion": 2, "mediaType": mediaManifestOCI,
+			"config": map[string]any{"mediaType": "application/vnd.oci.image.config.v1+json", "digest": digestOf(config), "size": len(config)},
+			"layers": []map[string]any{{"mediaType": "application/vnd.oci.image.layer.v1.tar+gzip", "digest": digestOf(layer), "size": len(layer)}},
+		})
+		dst.manifests[repository+"@"+digestOf(m)] = m
+		return digestOf(m), []string{digestOf(config), digestOf(layer)}
+	}
+	other := "s390x"
+	if runtime.GOARCH == other {
+		other = "amd64"
+	}
+	mine, mineBlobs := put(runtime.GOARCH)
+	theirs, theirBlobs := put(other)
+	index, _ := json.Marshal(map[string]any{
+		"schemaVersion": 2, "mediaType": mediaIndexOCI,
+		"manifests": []map[string]any{
+			{"mediaType": mediaManifestOCI, "digest": mine, "size": 1, "platform": map[string]string{"os": runtime.GOOS, "architecture": runtime.GOARCH}},
+			{"mediaType": mediaManifestOCI, "digest": theirs, "size": 1, "platform": map[string]string{"os": "linux", "architecture": other}},
+		},
+	})
+	dst.manifests[repository+"@"+digestOf(index)] = index
+	return digestOf(index), mineBlobs, theirBlobs
+}
+
+func TestABuildsBaseIsLinkedIntoItsRepositoryBeforeThePush(t *testing.T) {
+	dst := newRegistryOfRepositories()
+	server := httptest.NewServer(dst.handler())
+	defer server.Close()
+	address := strings.TrimPrefix(server.URL, "http://")
+	r := Registry{Address: address}
+
+	const from = "upstream/docker.io/library/golang"
+	index, mine, theirs := aBaseForThisMachine(t, dst, from)
+	bases := []string{
+		address + "/" + from + "@" + index,
+		// Not bases this registry holds: a package version, a tag, an image held nowhere here.
+		"@novox/mesh-sdk@1.2.3",
+		"golang:1-alpine",
+		"elsewhere.invalid/thing@sha256:" + strings.Repeat("e", 64),
+	}
+	n, err := r.LendBases(context.Background(), "mesh-tools-go/build", bases)
+	if err != nil {
+		t.Fatal(err)
+	}
+	// Every blob of this machine's platform is in the image's repository, so a push asks this machine's
+	// store for none of them; another platform's are not, since nothing built here stands on them.
+	for _, blob := range mine {
+		if !dst.links["mesh-tools-go/build"][blob] {
+			t.Fatalf("the base's blob %s is not in the image's repository", blob)
+		}
+	}
+	for _, blob := range theirs {
+		if dst.links["mesh-tools-go/build"][blob] {
+			t.Fatalf("another platform's blob %s was linked", blob)
+		}
+	}
+	if n != len(mine) || dst.mounts != len(mine) || dst.uploads != 0 {
+		t.Fatalf("%d linked, %d mounts, %d uploads; want %d mounts and no bytes moved", n, dst.mounts, dst.uploads, len(mine))
+	}
+
+	// Asked again, nothing is mounted twice.
+	if n, err := r.LendBases(context.Background(), "mesh-tools-go/build", bases); err != nil || n != 0 {
+		t.Fatalf("a second lending mounted %d: %v", n, err)
+	}
+}
+
+// A registry that will not mount is said, not hidden: the push is still tried, from the store.
+func TestABaseTheRegistryWillNotMountIsAnError(t *testing.T) {
+	dst := newRegistryOfRepositories()
+	dst.noMount = true
+	server := httptest.NewServer(dst.handler())
+	defer server.Close()
+	address := strings.TrimPrefix(server.URL, "http://")
+	index, _, _ := aBaseForThisMachine(t, dst, "upstream/thing")
+	_, err := Registry{Address: address}.LendBases(context.Background(), "hello/server",
+		[]string{address + "/upstream/thing@" + index})
+	if err == nil || !strings.Contains(err.Error(), "did not mount") {
+		t.Fatalf("a refused mount passed silently: %v", err)
+	}
+}
+
+// lending records what a build lent, and when, against the push.
+type lending struct {
+	*mirroring
+	order []string
+}
+
+func (l *lending) LendBases(_ context.Context, repository string, bases []string) (int, error) {
+	l.order = append(l.order, "lend "+repository+" "+strings.Join(bases, " "))
+	return len(bases), nil
+}
+
+func (l *lending) PublishImage(ctx context.Context, localTag, repository string) (string, error) {
+	l.order = append(l.order, "push "+repository)
+	return l.mirroring.PublishImage(ctx, localTag, repository)
+}
+
+func TestAnImageIsPushedOnlyAfterItsBasesAreLent(t *testing.T) {
+	r, workspace := aRepository(t, anImage, map[string]string{"modules/bus/Dockerfile": "ARG BASE\nFROM ${BASE}"})
+	r.contents["modules/bus/module.json"] = anImage
+	l := &lending{mirroring: &mirroring{recorded: r, at: "127.0.0.1:5000"}}
+	if _, err := Build(context.Background(), r.run, l, "https://forge.invalid/catalogue.git", "modules/bus", "", workspace,
+		nil, Npmrc{}, GitCredential{}, nil); err != nil {
+		t.Fatal(err)
+	}
+	want := []string{
+		"lend bus/server 127.0.0.1:5000/upstream/docker.io/vendor/server@sha256:" + strings.Repeat("1", 64),
+		"push bus/server",
+	}
+	if strings.Join(l.order, "\n") != strings.Join(want, "\n") {
+		t.Fatalf("the build did:\n%s\nwant:\n%s", strings.Join(l.order, "\n"), strings.Join(want, "\n"))
+	}
+}

internal/builder/reuse.go

@@ -257,6 +257,13 @@ func (s scratchPublisher) PublishArchive(ctx context.Context, repository string,
 	return s.to.PublishArchive(ctx, ScratchPrefix+repository, body, digest)
 }
 
+func (s scratchPublisher) LendBases(ctx context.Context, repository string, bases []string) (int, error) {
+	if l, can := s.to.(BaseLender); can {
+		return l.LendBases(ctx, ScratchPrefix+repository, bases)
+	}
+	return 0, nil
+}
+
 func (s scratchPublisher) MirrorImage(ctx context.Context, from, repository string) (string, error) {
 	m, can := s.to.(Mirrorer)
 	if !can {
@@ -487,11 +494,15 @@ func (r Registry) Discard(ctx context.Context, builds []CheckBuild) error {
 func (r Registry) letGo(ctx context.Context, checks, all map[string]checkIndex) (int, error) {
 	store := r.store()
 	stays := map[string]bool{}
+	// recorded are the records under a key another check still names (novox/hq issue 703): a later check that kept
+	// the build names it as the check's that built it, and the walk finds it by that record.
+	recorded := map[string]bool{}
 	for tag, c := range all {
 		if _, going := checks[tag]; going {
 			continue
 		}
 		for _, b := range c.Builds {
+			recorded[b.Module+" "+b.Key+" "+b.Check] = true
 			for _, m := range b.Made {
 				stays[catalogue.Recorded(m.Reference)] = true
 			}
@@ -516,8 +527,10 @@ func (r Registry) letGo(ctx context.Context, checks, all map[string]checkIndex)
 				}
 			}
 			// The record under the key, only while it is still this check's: a later check of the same key
-			// replaced it, and that one is its own check's to let go of.
+			// replaced it, and that one is its own check's to let go of. A build a check kept is that build's
-			if kept, found, err := r.Find(ctx, b.Module, b.Key); err == nil && found && kept.Check == c.Check {
+			// check's record, and goes with the last check naming it (novox/hq issue 703).
+			if kept, found, err := r.Find(ctx, b.Module, b.Key); err == nil && found &&
+				(kept.Check == c.Check || kept.Check == b.Check) && !recorded[b.Module+" "+b.Key+" "+kept.Check] {
 				if err := store.DeleteTagged(ctx, ScratchPrefix+b.Module, tagOf(b.Key)); err != nil && !errors.Is(err, artifacts.Gone) {
 					ok = false
 					failed = append(failed, fmt.Sprintf("%s's record: %v", b.Module, err))
@@ -603,6 +616,8 @@ func unnamed(named []NamedBuild, module, key string, found CheckBuild) string {
 			return ""
 		}
 	}
-	return "a build is kept under this key, and no check verdict of the walk's pull requests names it with its " +
+	// A build of another pull request, or of a head the forge did not merge, is in no verdict the walk is handed
-		"digests: not taken"
+	// (novox/hq issue 703): said with the check that made it, whose head names which head it was.
+	return "a build is kept under this key, by " + found.Said() + ", and no check verdict of the walk's pull requests " +
+		"at the head the forge merged names it with its digests: not taken"
 }

internal/builder/reuse_test.go

@@ -6,6 +6,7 @@ import (
 	"errors"
 	"net/http"
 	"net/http/httptest"
+	"reflect"
 	"slices"
 	"strconv"
 	"strings"
@@ -215,7 +216,8 @@ func TestARecordNoVerdictNamesIsRefusedAndBuilt(t *testing.T) {
 			if got.Reused != nil || len(scratch.took) > 0 || !dockerBuilt(r) {
 				t.Fatalf("a record no verdict names was taken: %+v, copied %v", got.Reused, scratch.took)
 			}
-			if !strings.Contains(got.Why, "no check verdict of the walk's pull requests names it") {
+			if !strings.Contains(got.Why, "no check verdict of the walk's pull requests at the head the forge merged names it") ||
+				!strings.Contains(got.Why, "at head abcdefabcdef") {
 				t.Fatalf("the walk says %q", got.Why)
 			}
 		})
@@ -625,3 +627,153 @@ func TestABuildTwoChecksShareGoesWithTheLastOfThem(t *testing.T) {
 		t.Fatal("the build stayed after the last check naming it went")
 	}
 }
+
+// aCheckAgain is a later check (build-2) of aPull building the module from a tree, with the builds the build seat's
+// verdicts name for it (novox/hq issue 703).
+func aCheckAgain(t *testing.T, scratch *aScratch, tree string, leave []NamedBuild) (CheckBuilt, *recorded) {
+	t.Helper()
+	return aCheckOf(t, scratch, aPull, "abcdefabcdef", tree, leave)
+}
+
+// aCheckOf is a later check (build-2) of a pull request at a head, the trunk moved since build-1.
+func aCheckOf(t *testing.T, scratch *aScratch, pull PullRef, head, tree string, leave []NamedBuild) (CheckBuilt, *recorded) {
+	t.Helper()
+	r, run, workspace := aModuleAt(t, tree)
+	spec := CheckSpec{ID: "build-2", Owner: pull.Owner, Repo: pull.Repo, Number: pull.Number,
+		Builds: []CheckBuildSpec{{Module: "meshboard", Repository: "https://forge.invalid/meshboard.git", Path: "mod",
+			Ref: "main"}}}
+	built := buildForTheMerge(t.Context(), run, spec, CheckBuilding{Publish: r, Scratch: scratch, Named: leave},
+		workspace, "", "", CheckVerdict{Head: head, Trunk: "654321654321"}, GitCredential{}, nil, logging(nil))
+	if len(built) != 1 || built[0].NotBuilt != "" || built[0].Key == "" {
+		t.Fatalf("the second check did not answer the module for its merge: %+v", built)
+	}
+	return built[0], r
+}
+
+// A check asked again when only the trunk moved, whose key is unchanged, builds nothing: it keeps the build an
+// earlier verdict names and names it by key and digest, so the walk can take it (novox/hq issue 703).
+func TestASecondCheckWhoseKeyIsUnchangedBuildsNothingAndNamesTheEarlierBuild(t *testing.T) {
+	withVersion(t, "builder-1")
+	scratch := newScratch()
+	first := aCheckBuilt(t, scratch, "tree-one")
+
+	again, r := aCheckAgain(t, scratch, "tree-one", named(first))
+	if dockerBuilt(r) || len(r.images) > 0 || len(r.archives) > 0 {
+		t.Fatalf("the second check built again: ran %v, published %v %v", r.ran, r.images, r.archives)
+	}
+	if again.Key != first.Key || again.Kept != "build-1" || !reflect.DeepEqual(again.Made, first.Made) {
+		t.Fatalf("the second check names %+v, not the first check's build %+v", again, first)
+	}
+	// The walk takes it by what the second verdict names.
+	leave := named(again)
+	leave[0].Check = again.Kept
+	w, run, workspace := aModuleAt(t, "tree-one")
+	got, err := BuildReusing(t.Context(), run, w, Reuse{Scratch: scratch, Pulls: []PullRef{aPull}, Named: leave},
+		"https://forge.invalid/meshboard.git", "mod", "main", workspace, nil, Npmrc{}, GitCredential{}, nil)
+	if err != nil || got.Reused == nil || dockerBuilt(w) {
+		t.Fatalf("the walk did not take the kept build: %v, why %q", err, got.Why)
+	}
+}
+
+// A check whose key changed builds, as before.
+func TestASecondCheckWhoseKeyChangedBuilds(t *testing.T) {
+	withVersion(t, "builder-1")
+	scratch := newScratch()
+	first := aCheckBuilt(t, scratch, "tree-one")
+
+	again, r := aCheckAgain(t, scratch, "tree-two", named(first))
+	if !dockerBuilt(r) || again.Kept != "" || again.Key == first.Key {
+		t.Fatalf("a check whose key changed did not build: %+v", again)
+	}
+}
+
+// A scratch record no verdict names is never kept: the store takes writes from anything on its network, so a
+// check builds rather than name a planted record (novox/hq issue 703, ADR 0350 §2).
+func TestASecondCheckKeepsNoRecordAVerdictDoesNotName(t *testing.T) {
+	withVersion(t, "builder-1")
+	scratch := newScratch()
+	first := aCheckBuilt(t, scratch, "tree-one")
+	for name, leave := range map[string][]NamedBuild{
+		"no verdict": nil,
+		"another digest": func() []NamedBuild {
+			n := named(first)
+			n[0].Digests["server"] = "sha256:" + strings.Repeat("e", 64)
+			return n
+		}(),
+		"another key": func() []NamedBuild { n := named(first); n[0].Key = "r1:" + strings.Repeat("f", 64); return n }(),
+	} {
+		t.Run(name, func(t *testing.T) {
+			again, r := aCheckAgain(t, scratch, "tree-one", leave)
+			if !dockerBuilt(r) || again.Kept != "" {
+				t.Fatalf("a record no verdict names was kept: %+v", again)
+			}
+		})
+	}
+}
+
+// A build a later check kept stays when the check that built it goes: its artifacts and its record, which the later
+// check's verdict names (novox/hq issue 703, ADR 0350 §5).
+func TestABuildALaterCheckKeptStaysWhenTheCheckThatBuiltItGoes(t *testing.T) {
+	m := &aTaggingRegistry{aRegistryOfRepositories: newRegistryOfRepositories(), tags: map[string]map[string]string{}}
+	server := httptest.NewServer(m.serve())
+	defer server.Close()
+	address := strings.TrimPrefix(server.URL, "http://")
+	registry := Registry{Address: address}
+	ctx := t.Context()
+	now := time.Date(2026, 10, 14, 9, 0, 0, 0, time.UTC)
+
+	body := `{"mediaType":"` + mediaManifestOCI + `","layers":[]}`
+	digest := digestOf([]byte(body))
+	m.manifests["scratch/meshboard/server@"+digest] = []byte(body)
+	key := "r1:" + strings.Repeat("1", 64)
+	b := CheckBuild{Key: key, Module: "meshboard", Pull: aPull, Check: "build-1", At: now,
+		Made: []catalogue.Built{{Name: "server", Kind: "image", Reference: address + "/scratch/meshboard/server@" + digest}}}
+	if err := registry.Keep(ctx, aPull, "build-1", now, []CheckBuild{b}); err != nil {
+		t.Fatal(err)
+	}
+	// Another pull request's check keeps it: its own document names the build, which stays the first check's.
+	other := PullRef{Owner: "novox", Repo: "meshboard", Number: 8}
+	if err := registry.Keep(ctx, other, "build-2", now, []CheckBuild{b}); err != nil {
+		t.Fatal(err)
+	}
+	held := func() bool { _, ok := m.manifests["scratch/meshboard/server@"+digest]; return ok }
+	found := func() bool { _, ok, _ := registry.Find(ctx, "meshboard", key); return ok }
+
+	if n, err := registry.Forget(ctx, aPull); err != nil || n != 1 {
+		t.Fatalf("forgot %d (%v)", n, err)
+	}
+	if !held() || !found() {
+		t.Fatalf("the build a later check names went with the check that built it: held %v, record %v", held(), found())
+	}
+	if n, err := registry.Forget(ctx, other); err != nil || n != 1 {
+		t.Fatalf("forgot %d (%v)", n, err)
+	}
+	if held() || found() {
+		t.Fatalf("the build stayed after the last check naming it went: held %v, record %v", held(), found())
+	}
+}
+
+// Only an earlier check of the same pull request at the same head is kept from: another head of it, or another pull
+// request whose verdict names the same key and digests, builds (novox/hq issue 703).
+func TestACheckKeepsNoBuildOfAnotherHeadOrPullRequest(t *testing.T) {
+	withVersion(t, "builder-1")
+	other := PullRef{Owner: "novox", Repo: "meshboard", Number: 8}
+	for name, c := range map[string]struct {
+		pull PullRef
+		head string
+	}{
+		"another head":         {aPull, "999999999999"},
+		"another pull request": {other, "abcdefabcdef"},
+	} {
+		t.Run(name, func(t *testing.T) {
+			scratch := newScratch()
+			first := aCheckBuilt(t, scratch, "tree-one")
+			leave := named(first)
+			leave[0].Pull = c.pull // as if its own verdict named it
+			again, r := aCheckOf(t, scratch, c.pull, c.head, "tree-one", leave)
+			if !dockerBuilt(r) || again.Kept != "" {
+				t.Fatalf("a build of %s was kept: %+v", name, again)
+			}
+		})
+	}
+}

internal/catalogue/bus_snapshot_test.go

@@ -21,6 +21,16 @@ func TestTheBussAccountSaysNothingOnTheBus(t *testing.T) {
 		t.Fatalf("a bus module declaring what it emits was not refused, or not for the reason: %v", err)
 	}
 
+	// Its tools bundle says what it emits (novox/hq ADR 0357): the node's runtime carries the bundle and is
+	// granted the module's events, so a bus module that ships one may declare them.
+	bundled := []byte(`{"module":"bus","version":"1","provides":[{"name":"mesh-bus","scope":"mesh"}],
+		"claims":[{"name":"mesh-broker","scope":"mesh"}],"own-secrets":{"broker":"/run/broker"},
+		"emits":["bus.slow-consumer"],"tools":["bus_streams"],
+		"build":{"artifacts":[{"name":"tools","kind":"bundle","language":"go","system":"arch","from":"cmd/t","binary":"t"}]}}`)
+	if _, err := ParseManifest(bundled); err != nil {
+		t.Fatalf("a bus module whose tools bundle declares what it emits was refused: %v", err)
+	}
+
 	quiet := []byte(`{"module":"bus","version":"1","provides":[{"name":"mesh-bus","scope":"mesh"}],
 		"claims":[{"name":"mesh-broker","scope":"mesh"}],"own-secrets":{"broker":"/run/broker"},
 		"tools":["bus_streams"]}`)

internal/catalogue/manifest.go

@@ -552,6 +552,10 @@ type Manifest struct {
 	// why. A person's choice through the `upgrade` verb stands over it; the bus records whatever it says.
 	Upgrade *UpgradePolicy `json:"upgrade,omitempty"`
 
+	// Unhealthy is how loud this module's unhealthy condition is (novox/hq ADR 0355): a warning when unsaid;
+	// `urgent`, with why, for a module whose failure costs people something they rely on.
+	Unhealthy *UnhealthyPolicy `json:"unhealthy,omitempty"`
+
 	// Reads are other modules' state this module reads and watches, each `<module>.<name>`
 	// (novox/hq ADR 0201). Read-only: only the owner's instances write.
 	Reads []string `json:"reads,omitempty"`
@@ -1630,9 +1634,14 @@ func ParseManifest(raw []byte) (Manifest, error) {
 	// **The bus's own account copies the bus and says nothing on it** (novox/hq ADR 0235). The module
 	// holding mesh-broker is granted the snapshot API and nothing else, so anything it declared to say
 	// or hear on the bus would be granted nothing — refused here rather than silently dropped.
+	//
+	// **But its tools bundle may say what it declares** (novox/hq ADR 0357): the node's runtime carries
+	// the bundle and is granted the events the module emits, under the module's name, as for any module it
+	// carries — the bus's account is not who publishes them. So emits are refused only for a bus module
+	// with no bundle to say them.
 	if _, account := m.OwnSecrets["broker"]; account && m.ClaimsSeat(BrokerSeat) {
 		var said []string
-		if len(m.EmitsAll()) > 0 {
+		if len(m.EmitsAll()) > 0 && !m.shipsABundle() {
 			said = append(said, "emits")
 		}
 		for _, f := range []struct {
@@ -2321,6 +2330,7 @@ func ParseManifest(raw []byte) (Manifest, error) {
 	problems = append(problems, m.placementProblems()...)
 	problems = append(problems, m.dataProblems()...)
 	problems = append(problems, m.upgradeProblems()...)
+	problems = append(problems, m.unhealthyProblems()...)
 
 	for i, r := range m.Resources {
 		id, _ := r["id"].(string)
@@ -2897,3 +2907,16 @@ func whileStoppedProblems(m Manifest, r map[string]any, scheduled bool) []string
 	}
 	return problems
 }
+
+// shipsABundle says the module builds a tools bundle, which the node's runtime carries and speaks for.
+func (m Manifest) shipsABundle() bool {
+	if m.Build == nil {
+		return false
+	}
+	for _, a := range m.Build.Artifacts {
+		if a.Kind == ArtifactBundle {
+			return true
+		}
+	}
+	return false
+}

internal/catalogue/unhealthy.go

@@ -0,0 +1,55 @@
+package catalogue
+
+import (
+	"fmt"
+	"strings"
+)
+
+// How loud a module's unhealthy condition is (novox/hq ADR 0355, extending ADR 0240).
+//
+// **A module may declare its unhealthy urgent.** A module whose failure costs people something they rely on
+// (mail refused or stuck for everyone with a mailbox) says so with `unhealthy`, and its condition
+// `module.<module>.<machine>.unhealthy` is raised urgent instead of a warning. **Urgent needs a why**, as an
+// `upgrade` policy other than roll does: a person reading the catalogue sees what is lost while it is broken.
+
+// The severities a module may declare for its unhealthy condition.
+const (
+	// UnhealthyUrgent raises the module's unhealthy condition urgent, on every machine it runs on.
+	UnhealthyUrgent = "urgent"
+	// UnhealthyWarning is what a module's unhealthy condition is without the field, said out loud.
+	UnhealthyWarning = "warning"
+)
+
+// UnhealthyPolicy is what a module says about how loud its unhealthy condition is: `unhealthy` in its manifest
+// (novox/hq ADR 0355).
+type UnhealthyPolicy struct {
+	Severity string `json:"severity"`
+	// Why names what people lose while the module is broken. It is required: a module that says nothing of
+	// why it is loud is refused.
+	Why string `json:"why,omitempty"`
+}
+
+// unhealthyProblems refuses an `unhealthy` without a why, and any severity but urgent or warning (novox/hq ADR
+// 0355 §2).
+func (m Manifest) unhealthyProblems() []string {
+	if m.Unhealthy == nil {
+		return nil
+	}
+	var problems []string
+	switch m.Unhealthy.Severity {
+	case UnhealthyUrgent, UnhealthyWarning:
+	default:
+		problems = append(problems, fmt.Sprintf("unhealthy is %q or %q, not %q", UnhealthyUrgent, UnhealthyWarning,
+			m.Unhealthy.Severity))
+	}
+	if strings.TrimSpace(m.Unhealthy.Why) == "" {
+		problems = append(problems, "unhealthy says why: a module that declares how loud its failure is names "+
+			"what people lose while it is broken")
+	}
+	return problems
+}
+
+// UnhealthyIsUrgent is whether the module declares its unhealthy condition urgent (novox/hq ADR 0355 §1).
+func (m Manifest) UnhealthyIsUrgent() bool {
+	return m.Unhealthy != nil && m.Unhealthy.Severity == UnhealthyUrgent
+}

internal/catalogue/unhealthy_test.go

@@ -0,0 +1,53 @@
+package catalogue
+
+import (
+	"strings"
+	"testing"
+)
+
+// A module may declare its unhealthy urgent, with why; the module check refuses it without why and with any
+// severity but urgent or warning (novox/hq ADR 0355).
+
+func TestAnUnhealthyDeclaredUrgentIsUrgent(t *testing.T) {
+	m, err := ParseManifest([]byte(`{"module":"mail","version":"1",` +
+		`"unhealthy":{"severity":"urgent","why":"mail is refused or stuck for everyone with a mailbox"}}`))
+	if err != nil {
+		t.Fatalf("a manifest declaring its unhealthy urgent with why was refused: %v", err)
+	}
+	if !m.UnhealthyIsUrgent() {
+		t.Errorf("a manifest declaring its unhealthy urgent reads as not urgent: %+v", m.Unhealthy)
+	}
+}
+
+func TestAManifestWithoutUnhealthyIsNotUrgent(t *testing.T) {
+	m, err := ParseManifest([]byte(`{"module":"notes","version":"1"}`))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if m.UnhealthyIsUrgent() {
+		t.Errorf("a manifest saying nothing of its unhealthy reads as urgent")
+	}
+	warning := Manifest{Module: "notes", Unhealthy: &UnhealthyPolicy{Severity: UnhealthyWarning, Why: "notes wait"}}
+	if warning.UnhealthyIsUrgent() || len(warning.unhealthyProblems()) != 0 {
+		t.Errorf("a warning said with why reads as urgent or is refused: %v", warning.unhealthyProblems())
+	}
+}
+
+func TestAnUnhealthyWithoutWhyIsRefused(t *testing.T) {
+	for _, why := range []string{"", "   "} {
+		if problems := (Manifest{Module: "mail", Unhealthy: &UnhealthyPolicy{Severity: UnhealthyUrgent, Why: why}}).unhealthyProblems(); len(problems) == 0 {
+			t.Errorf("urgent with why %q was accepted", why)
+		}
+	}
+	if _, err := ParseManifest([]byte(`{"module":"mail","version":"1","unhealthy":{"severity":"urgent"}}`)); err == nil ||
+		!strings.Contains(err.Error(), "unhealthy says why") {
+		t.Errorf("a manifest declaring its unhealthy urgent without why parsed: %v", err)
+	}
+}
+
+func TestAnUnhealthySeverityOtherThanUrgentOrWarningIsRefused(t *testing.T) {
+	if _, err := ParseManifest([]byte(`{"module":"mail","version":"1","unhealthy":{"severity":"loud","why":"mail stops"}}`)); err == nil ||
+		!strings.Contains(err.Error(), `not "loud"`) {
+		t.Errorf("a manifest declaring its unhealthy loud parsed: %v", err)
+	}
+}

internal/catalogue/verbs.go

@@ -362,6 +362,28 @@ var ControllerVerbs = []Verb{
 			"register": "\"true\" to register what it builds",
 			"older":    "\"true\", with register: even though a newer build of the module is registered",
 		}, []string{"id"}, "register", "older")},
+	// novox/hq issue 686: a builder ran a branch's store tests for the first time in its pull request's merge check.
+	{Name: "try", Description: "Try a pushed branch or commit before its pull request (novox/hq issue 686): the build " +
+		"seat merges it into the repository's trunk and runs the repository's own merge-check.sh on the merge, in the " +
+		"toolchain containers and against the throwaway store and bus a pull request's merge check gets. Answers at " +
+		"once with an id; asked again with that id it waits up to 20 s and answers pass, fail or error, how long it " +
+		"took and the lines naming what failed — or that it is still waiting or running, to ask again. Sets no " +
+		"status on the forge, registers and builds nothing, runs no merge gate, counts as a check in the build queue " +
+		"(after deliveries and after every pull request's check, however long it waits) and is bounded as one. One " +
+		"try of a commit at a time — a second ask answers the first's id — and at most four waiting or running in " +
+		"all: a fifth is refused. Only for a repository of the mesh; the ref must be on the forge.",
+		Input: schema(map[string]string{
+			"repository": "the repository on the forge, owner/name; with ref",
+			"ref":        "the branch or commit to try, as pushed to the forge",
+			"base": "the branch it is merged into (the repository's default branch when none is named). The " +
+				"merge-check.sh that runs is that branch's, never the ref's own: the same trust as a pull request's base",
+			"tests": "only the tests this `go test -run` pattern names, where the repository's merge-check.sh reads " +
+				"MESH_CHECK_TESTS; a script that does not runs whole",
+			"store-only": "\"true\": only the repository's store tests, where its merge-check.sh reads " +
+				"MESH_CHECK_STORE_ONLY",
+			"id": "instead of a repository: the id a try answered, to read what came of it",
+		}, nil, "store-only"),
+		Replaces: []string{"sh merge-check.sh", "docker run postgres"}},
 	// novox/hq ADR 0350 §5: asked by the delivery's owner when the forge says a pull request closed unmerged.
 	{Name: "forget-checks", Description: "Let go of every build a pull request's merge checks made for its merge in " +
 		"the artifact store's scratch namespace (novox/hq ADR 0350 §5): asked when it closed unmerged; a merged one's go " +

internal/inventory/plans.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"slices"
 	"strings"
 	"time"
 
@@ -103,6 +104,9 @@ type PlanMerge struct {
 	Number int      `json:"number,omitempty"`
 	Title  string   `json:"title,omitempty"`
 	Moves  []string `json:"moves,omitempty"`
+	// Head is the pull request's head commit the forge merged (novox/hq issue 703): the walk takes only a build a
+	// check of that head made. Empty where the announcement said none, and then it takes none.
+	Head string `json:"head,omitempty"`
 	// Merged is when the forge made the merge and Heard when the controller heard it (novox/hq ADR 0282): where
 	// its delivery time starts. Zero for a merge named before they were kept.
 	Merged time.Time `json:"merged,omitzero"`
@@ -391,6 +395,65 @@ type PlanGate struct {
 	// reports its module's container left running because it said busy, the judging waits and has not
 	// started; once it reports the container replaced, Since is moved to then. Nil when nothing waited.
 	Busy *GateBusy `json:"busy,omitempty"`
+	// Pending says the send this gate judges is kept and not yet made (novox/hq ADR 0353 §8): a controller that
+	// takes over reads the machine's last send before making it, and never sends it twice.
+	Pending bool `json:"pending,omitempty"`
+	// Silent says the machine reported nothing on its send within ApplySilentAfter (novox/hq ADR 0353 §4): left,
+	// neither failed nor put back.
+	Silent bool `json:"silent,omitempty"`
+	// TookOver names the gate whose readings this one took over (novox/hq ADR 0353 §7): another walk's judging of
+	// the same build on the same machine, which this gate goes on from instead of starting from zero.
+	TookOver string `json:"took_over,omitempty"`
+}
+
+// TakeReadings makes this gate go on from another's readings of the same build on the same machine (novox/hq ADR
+// 0353 §7): when the judging began, when each machine applied, the passes counted and when, and what each found.
+// A module's own count is taken only for the modules this gate judges.
+func (g *PlanGate) TakeReadings(from *PlanGate, modules []string, id string) {
+	if from == nil {
+		return
+	}
+	if from.Since != nil {
+		since := *from.Since
+		g.Since = &since
+	}
+	for n, s := range from.Sent {
+		if slices.Contains(g.Machines, n) {
+			if g.Sent == nil {
+				g.Sent = map[string]SentDeclaration{}
+			}
+			g.Sent[n] = s
+		}
+	}
+	for n, at := range from.Applied {
+		if slices.Contains(g.Machines, n) {
+			if g.Applied == nil {
+				g.Applied = map[string]time.Time{}
+			}
+			g.Applied[n] = at
+		}
+	}
+	g.Passes, g.Faulted, g.HealthySeen, g.Last = from.Passes, from.Faulted, from.HealthySeen, from.Last
+	if from.LastPass != nil {
+		at := *from.LastPass
+		g.LastPass = &at
+	}
+	for _, m := range modules {
+		if n, counted := from.Healthy[m]; counted {
+			if g.Healthy == nil {
+				g.Healthy = map[string]int{}
+			}
+			g.Healthy[m] = n
+		}
+		if at, counted := from.HealthyAt[m]; counted {
+			if g.HealthyAt == nil {
+				g.HealthyAt = map[string]time.Time{}
+			}
+			g.HealthyAt[m] = at
+		}
+	}
+	g.Readings = append([]GateReading(nil), from.Readings...)
+	g.TookOver = id
 }
 
 // GateBusy is a first-node gate's wait for a busy container (novox/hq ADR 0335 §4).
@@ -477,8 +540,16 @@ type CarriedMove struct {
 type PlanRelease struct {
 	Order []string `json:"order"`
 	Next  int      `json:"next"`
-	// Gate is the machine being judged; nil between machines.
+	// Gate is the first machine being judged; nil between machines.
 	Gate *PlanGate `json:"gate,omitempty"`
+	// Rest says the first machine passed (novox/hq ADR 0353 §1): every other machine is sent at once, each judged by
+	// its own gate in Gates, by machine — a build no gate passed going to one machine of a step only (§2).
+	Rest  bool                 `json:"rest,omitempty"`
+	Gates map[string]*PlanGate `json:"gates,omitempty"`
+	// Failed are the machines of the rest whose gate failed, and Silent those that said nothing on their send
+	// within ApplySilentAfter (ADR 0353 §3 and §4).
+	Failed []string `json:"failed,omitempty"`
+	Silent []string `json:"silent,omitempty"`
 	Done   []string `json:"done,omitempty"`
 	// Skipped are the machines not heard from when their turn came, left as they were.
 	Skipped []string `json:"skipped,omitempty"`

internal/lease/lease.go

@@ -10,13 +10,23 @@
 //	controller A (epoch 41)  ──renew──renew──╳ (renewal refused)──► stops acting, exits
 //	controller B             ──wait──────────────take (epoch 57)──► acts
 //
-// **Three ways an instance stops acting, all at once.** A renewal refused — somebody else wrote the key
+// **A renewal that fails is not a lost lease** (novox/hq issue 477, the operator's standing rule). A
-// — is a loss, said and final: Lost closes and the process exits, so its service manager restarts it as
+// renewal the bus did not answer in time — a stall of its JetStream API — says nothing about another
-// a candidate. A renewal that cannot be made in time is the same, because past its time the key may be
+// holder: none can take the key while it lives. So the instance keeps the lease it holds until the key's
-// somebody else's. And Epoch, the gate every act passes, answers an error from the moment the last
+// own age has passed without a successful renewal, and tries again every renewal interval:
-// renewal is older than the key's age less a margin — **before** another instance could have taken
+//
-// it, whatever the renewing goroutine is doing — so a send in flight at the moment of loss is refused
+//	renewed ──╳ (no answer)──╳──────────── renewed ──► acts on, as before
-// by the clock, not by a goroutine that may be stuck.
+//	   0         ½ age: no new act starts   (the gate opens again)
+//	renewed ──╳──────╳──────╳──────╳ age ──► lost, exits
+//
+// **Two ways an instance loses the lease, said and final**: Lost closes and the process exits, so its
+// service manager restarts it as a candidate. Another holder seen — the renewal refused because the
+// key moved, and the key naming somebody else or gone — is a loss at once. The key's age passed with no
+// successful renewal is a loss too, because past it the key may be somebody else's. And Epoch, the gate
+// every act passes, answers an error from the moment the last renewal is older than half the key's age
+// (or its age less a margin, if that is sooner) — **long before** another instance could have taken it,
+// whatever the renewing goroutine is doing — so a send in flight while the bus stalls is refused by the
+// clock, not by a goroutine that may be stuck, and the gate opens again with the next renewal made.
 package lease
 
 import (
@@ -95,6 +105,11 @@ type Options struct {
 	// Health is asked at every take and renewal for the holder's word about itself (witness.go); nil
 	// writes none.
 	Health func() *Health
+	// Delayed is told of every renewal that failed without losing the lease — the bus did not answer
+	// in time — with why, when the lease was last renewed, and when it is lost unless a renewal is made
+	// first. It is where a bus stall is said as one (novox/hq issue 478); nil tells nobody. It is called
+	// on the renewing goroutine and must not block.
+	Delayed func(why error, renewed, lostBy time.Time)
 }
 
 // Lease is one instance's hold, or its wait for one.
@@ -110,14 +125,22 @@ type Lease struct {
 	held     bool
 	epoch    uint64
 	revision uint64
-	// validUntil is when this instance stops acting unless it renews: the moment before its last
+	// validUntil is when this instance stops starting acts unless it renews: the moment before its last
-	// renewal was sent, plus the key's age, less the margin.
+	// renewal was sent, plus half the key's age (or the age less the margin, if sooner).
 	validUntil time.Time
+	// keptUntil is when this instance loses the lease unless it renews: the moment before its last
+	// renewal was sent, plus the key's age (novox/hq issue 477).
+	keptUntil time.Time
 	// renewed is when this instance last took or renewed the key.
 	renewed time.Time
+	// failing is how many renewals failed since the last one made, and failingSince when the first did.
+	failing      int
+	failingSince time.Time
 	lostWhy      error
 	lost         chan struct{}
 	taken        time.Time
+	// update writes the key at a revision: the bucket's own, or a test's bus that does not answer.
+	update func(ctx context.Context, key string, value []byte, last uint64) (uint64, error)
 }
 
 // Open is a lease over the bucket, read for its age. The bucket is the caller's to assert.
@@ -161,7 +184,7 @@ func Open(ctx context.Context, js jetstream.JetStream, bucket string, o Options)
 		return nil, fmt.Errorf("a lease renewed every %s with a margin of %s does not fit a key that lives %s",
 			o.RenewEvery, o.Margin, status.TTL())
 	}
-	return &Lease{kv: kv, stream: stream, ttl: status.TTL(), o: o, lost: make(chan struct{})}, nil
+	return &Lease{kv: kv, stream: stream, ttl: status.TTL(), o: o, lost: make(chan struct{}), update: kv.Update}, nil
 }
 
 // TTL is how long the key lives unrenewed.
@@ -284,8 +307,8 @@ func (l *Lease) TryTake(ctx context.Context) (uint64, error) {
 			"back to be taken again", revision, floor)
 	}
 	l.mu.Lock()
-	l.held, l.epoch, l.revision, l.taken, l.renewed = true, revision, revision, now, anchor
+	l.held, l.epoch, l.revision, l.taken = true, revision, revision, now
-	l.validUntil = anchor.Add(l.ttl - l.o.Margin)
+	l.renewedAt(anchor)
 	l.mu.Unlock()
 	l.o.Say("took the controller lease at epoch %d (%s)", revision, h.Instance)
 	return revision, nil
@@ -331,8 +354,20 @@ func (l *Lease) aboveTheFloor(ctx context.Context) error {
 	return nil
 }
 
+// renewedAt records a take or renewal sent at anchor: the gate open until half the key's age (or its age
+// less the margin, if sooner), the lease kept until its age. Called with mu held.
+func (l *Lease) renewedAt(anchor time.Time) {
+	open := l.ttl / 2
+	if l.ttl-l.o.Margin < open {
+		open = l.ttl - l.o.Margin
+	}
+	l.renewed, l.validUntil, l.keptUntil = anchor, anchor.Add(open), anchor.Add(l.ttl)
+	l.failing, l.failingSince = 0, time.Time{}
+}
+
 // Epoch is the gate every act passes: this instance's epoch while it holds the lease and its last
-// renewal is in time, and an error otherwise — not held, lost, or a renewal overdue.
+// renewal is in time, and an error otherwise — not held, lost, or a renewal overdue by half the key's
+// age, which a renewal made opens again (novox/hq issue 477).
 func (l *Lease) Epoch() (uint64, error) {
 	l.mu.Lock()
 	defer l.mu.Unlock()
@@ -342,8 +377,9 @@ func (l *Lease) Epoch() (uint64, error) {
 	case !l.held:
 		return 0, ErrNotHeld
 	case l.o.Now().After(l.validUntil):
-		return 0, fmt.Errorf("%w in time: its last renewal was due by %s", ErrNotHeld,
+		return 0, fmt.Errorf("%w in time: no renewal was made since %s, so no new act starts until one is "+
-			l.validUntil.UTC().Format(time.RFC3339))
+			"(the lease is kept until %s)", ErrNotHeld, l.renewed.UTC().Format(time.RFC3339),
+			l.keptUntil.UTC().Format(time.RFC3339))
 	}
 	return l.epoch, nil
 }
@@ -371,25 +407,41 @@ func (l *Lease) LostWhy() error {
 	return l.lostWhy
 }
 
-// Keep renews the lease until ctx ends or a renewal fails; on a failure it is lost.
+// Keep renews the lease until ctx ends or it is lost. A renewal that fails without losing it is tried
+// again at the next interval, and the lease is lost when its key's age passes with none made, even while
+// a renewal hangs (novox/hq issue 477).
 func (l *Lease) Keep(ctx context.Context) {
 	tick := time.NewTicker(l.o.RenewEvery)
 	defer tick.Stop()
 	for {
+		var expire <-chan time.Time
+		l.mu.Lock()
+		if l.failing > 0 {
+			expire = time.After(l.keptUntil.Sub(l.o.Now()))
+		}
+		l.mu.Unlock()
 		select {
 		case <-ctx.Done():
 			return
 		case <-tick.C:
+		case <-expire:
 		}
-		if err := l.Renew(ctx); err != nil {
+		_ = l.Renew(ctx)
+		if ctx.Err() != nil || l.LostWhy() != nil {
 			return // lost, said by lose; or stopping
 		}
 	}
 }
 
-// Renew writes the key once more at the revision this instance last wrote. A refusal or a failure is
+// ErrDelayed is a renewal that failed without losing the lease: the bus did not answer in time, and the
-// the lease lost: past this renewal's time the key may be somebody else's, and an instance that is not
+// key's age has not passed since the last renewal made (novox/hq issue 477).
-// sure it holds the lease does not act on it.
+var ErrDelayed = errors.New("the lease's renewal is delayed")
+
+// Renew writes the key once more at the revision this instance last wrote. Another holder seen — the
+// write refused and the key naming somebody else, or gone — is the lease lost at once. A renewal that
+// cannot be made — the bus does not answer in time — is not (novox/hq issue 477): it answers ErrDelayed,
+// the lease is kept, and the gate closes only once half the key's age has passed without a renewal made.
+// The lease is lost when the whole age has: past it the key may be somebody else's.
 func (l *Lease) Renew(ctx context.Context) error {
 	l.mu.Lock()
 	if !l.held || l.lostWhy != nil {
@@ -399,12 +451,15 @@ func (l *Lease) Renew(ctx context.Context) error {
 		}
 		return ErrNotHeld
 	}
-	revision, epoch, taken := l.revision, l.epoch, l.taken
+	revision, epoch, taken, keptUntil := l.revision, l.epoch, l.taken, l.keptUntil
 	l.mu.Unlock()
 
+	anchor := l.o.Now()
+	if !anchor.Before(keptUntil) {
+		return l.lose(l.overdue(nil))
+	}
 	h := l.o.Holder
 	h.Epoch, h.Taken = epoch, taken
-	anchor := l.o.Now()
 	h.Renewed = anchor
 	if l.o.Health != nil {
 		h.Health = l.o.Health()
@@ -413,27 +468,107 @@ func (l *Lease) Renew(ctx context.Context) error {
 	if err != nil {
 		return l.lose(err)
 	}
-	renewing, cancel := context.WithTimeout(ctx, l.o.RenewWithin)
+	// One renewal waits no longer than its own bound, nor past the moment the lease is lost without it.
+	within := l.o.RenewWithin
+	if left := keptUntil.Sub(anchor); left < within {
+		within = left
+	}
+	renewing, cancel := context.WithTimeout(ctx, within)
 	defer cancel()
-	next, err := l.kv.Update(renewing, Key, value, revision)
+	next, err := l.update(renewing, Key, value, revision)
+	if err != nil && ctx.Err() == nil && (errors.Is(err, jetstream.ErrKeyExists) || isWrongLast(err)) {
+		// The key moved. A renewal whose answer the stall swallowed may have been written all the same:
+		// the key still naming this instance at this epoch is that one, and is renewed at the revision it
+		// has. Anything else is another holder — or the key gone, free for one — and the lease lost.
+		var why error
+		next, why, err = l.renewMoved(renewing, epoch, value, revision, err)
+		if why != nil {
+			return l.lose(why)
+		}
+	}
 	if err != nil {
 		if ctx.Err() != nil {
 			// Stopping, not losing: Release gives it back.
 			return ctx.Err()
 		}
-		why := fmt.Errorf("the renewal at revision %d was refused: %w", revision, err)
+		return l.delayed(fmt.Errorf("the renewal could not be made: %w", err))
-		if !errors.Is(err, jetstream.ErrKeyExists) && !isWrongLast(err) {
-			why = fmt.Errorf("the renewal could not be made: %w", err)
-		}
-		return l.lose(why)
 	}
 	l.mu.Lock()
-	l.revision, l.renewed = next, anchor
+	failed, since := l.failing, l.failingSince
-	l.validUntil = anchor.Add(l.ttl - l.o.Margin)
+	l.revision = next
+	l.renewedAt(anchor)
 	l.mu.Unlock()
+	if failed > 0 {
+		l.o.Say("renewed the controller lease (epoch %d) after %d renewal(s) that could not be made since %s: "+
+			"this controller acts again", epoch, failed, since.UTC().Format(time.RFC3339))
+	}
 	return nil
 }
 
+// renewMoved is a renewal the bus refused because the key moved: the renewal made at the key's revision
+// when the key is still this instance's at this epoch, the lease lost (why) when it is somebody else's or
+// gone, and an error when the key cannot be read — a renewal not made, which loses nothing yet.
+func (l *Lease) renewMoved(ctx context.Context, epoch uint64, value []byte, revision uint64,
+	refused error) (next uint64, lost error, err error) {
+	entry, err := l.kv.Get(ctx, Key)
+	if errors.Is(err, jetstream.ErrKeyNotFound) {
+		return 0, fmt.Errorf("the renewal at revision %d was refused and the key is gone, free for another "+
+			"controller to take: %w", revision, refused), nil
+	}
+	if err != nil {
+		return 0, nil, fmt.Errorf("the renewal at revision %d was refused (%v) and the key could not be read: %w",
+			revision, refused, err)
+	}
+	var h Holder
+	mine := json.Unmarshal(entry.Value(), &h) == nil && h.Instance == l.o.Holder.Instance &&
+		(h.Epoch == epoch || h.Epoch == 0 && entry.Revision() == epoch)
+	if !mine {
+		return 0, fmt.Errorf("the renewal at revision %d was refused: another holder wrote the key (%s, epoch %d, "+
+			"revision %d): %w", revision, h.Instance, h.Epoch, entry.Revision(), refused), nil
+	}
+	next, err = l.update(ctx, Key, value, entry.Revision())
+	return next, nil, err
+}
+
+// delayed is a renewal that could not be made: said at the first of a run, told to Delayed, and the lease
+// kept — or lost, when its key's age has passed meanwhile.
+func (l *Lease) delayed(why error) error {
+	l.mu.Lock()
+	now := l.o.Now()
+	if !now.Before(l.keptUntil) {
+		l.mu.Unlock()
+		return l.lose(l.overdue(why))
+	}
+	l.failing++
+	if l.failing == 1 {
+		l.failingSince = now
+	}
+	first, epoch, renewed, validUntil, keptUntil := l.failing == 1, l.epoch, l.renewed, l.validUntil, l.keptUntil
+	l.mu.Unlock()
+	if first {
+		l.o.Say("the controller lease (epoch %d) could not be renewed: %v — it is kept: no new act starts after "+
+			"%s and it is lost at %s unless a renewal is made first", epoch, why,
+			validUntil.UTC().Format(time.RFC3339), keptUntil.UTC().Format(time.RFC3339))
+	}
+	if l.o.Delayed != nil {
+		l.o.Delayed(why, renewed, keptUntil)
+	}
+	return fmt.Errorf("%w: %w", ErrDelayed, why)
+}
+
+// overdue is why a lease whose key's age passed unrenewed is lost, with the last renewal's failure.
+func (l *Lease) overdue(last error) error {
+	l.mu.Lock()
+	renewed, failing := l.renewed, l.failing
+	l.mu.Unlock()
+	why := fmt.Errorf("no renewal was made within the key's age of %s (the last at %s, %d failed since)",
+		l.ttl, renewed.UTC().Format(time.RFC3339), failing)
+	if last != nil {
+		why = fmt.Errorf("%w: %w", why, last)
+	}
+	return why
+}
+
 // isWrongLast is the bus refusing a compare-and-set because the key moved.
 func isWrongLast(err error) bool {
 	var apiErr *jetstream.APIError

internal/lease/lease_test.go

@@ -4,7 +4,9 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"strings"
 	"sync"
+	"sync/atomic"
 	"testing"
 	"time"
 
@@ -289,3 +291,200 @@ func TestALeaseBucketWithoutAnAgeIsRefused(t *testing.T) {
 		t.Fatal("a lease over keys that never expire was opened: a controller that died holding it would hold it for ever")
 	}
 }
+
+// A bus that stalls (novox/hq issue 477): a renewal it does not answer in time is not a lost lease. The
+// holder keeps the lease until the key's age passes with no renewal made, starts no new act once half of
+// it has, acts again on the next renewal made, and loses it at once only to another holder.
+
+// stallable puts l's renewals on a bus that stalls while the answer is true, as one whose JetStream API
+// does: each renewal waits out its bound and fails with the deadline. landed is a stall that swallows
+// only the answer: the write is made. Called before l is kept.
+func stallable(l *Lease, landed bool) *atomic.Bool {
+	real := l.update
+	stalled := new(atomic.Bool)
+	l.update = func(ctx context.Context, key string, value []byte, last uint64) (uint64, error) {
+		if !stalled.Load() {
+			return real(ctx, key, value, last)
+		}
+		if landed {
+			_, _ = real(ctx, key, value, last)
+		}
+		<-ctx.Done()
+		return 0, ctx.Err()
+	}
+	return stalled
+}
+
+// keeping takes the lease for l and keeps it until the test ends, answering the epoch.
+func keeping(t *testing.T, l *Lease) uint64 {
+	t.Helper()
+	epoch, err := l.Take(t.Context())
+	if err != nil {
+		t.Fatal(err)
+	}
+	go l.Keep(t.Context())
+	return epoch
+}
+
+// delays is told of every renewal that failed without losing l's lease.
+func delays(l *Lease) <-chan error {
+	told := make(chan error, 64)
+	l.o.Delayed = func(why error, _, _ time.Time) {
+		select {
+		case told <- why:
+		default:
+		}
+	}
+	return told
+}
+
+func TestAFailedRenewalKeepsTheLeaseUntilItsTTL(t *testing.T) {
+	_, bucket := aBucket(t)
+	a := aController(t, bucket, "a", nil)
+	told := delays(a)
+	stalled := stallable(a, false)
+	epoch := keeping(t, a)
+	stalled.Store(true)
+
+	select {
+	case why := <-told:
+		if !errors.Is(why, context.DeadlineExceeded) {
+			t.Fatalf("a renewal the bus did not answer was told as %v", why)
+		}
+	case <-time.After(3 * testRenew):
+		t.Fatal("a renewal the bus did not answer was told to nobody")
+	}
+	renewed := a.Renewed()
+	const slack = 150 * time.Millisecond
+	// Within the key's age the lease is kept, though no renewal is made: no other controller could take it.
+	for time.Now().Before(renewed.Add(testTTL - slack)) {
+		select {
+		case <-a.Lost():
+			t.Fatalf("a lost the lease %s after its last renewal, within the key's age of %s: %v",
+				time.Since(renewed), testTTL, a.LostWhy())
+		default:
+		}
+		since := time.Since(renewed)
+		e, err := a.Epoch()
+		switch {
+		case since < testTTL/2-slack && (err != nil || e != epoch):
+			t.Fatalf("a starts no act %s after its last renewal, within half the key's age: %d, %v", since, e, err)
+		case since > testTTL/2+slack && !errors.Is(err, ErrNotHeld):
+			t.Fatalf("a still starts acts %s after its last renewal, past half the key's age: %d, %v", since, e, err)
+		}
+		time.Sleep(20 * time.Millisecond)
+	}
+	// Past it, the lease is lost: the key may be somebody else's.
+	select {
+	case <-a.Lost():
+	case <-time.After(2 * slack):
+		t.Fatalf("a still holds the lease %s after its last renewal, past the key's age of %s",
+			time.Since(renewed), testTTL)
+	}
+	if why := a.LostWhy(); why == nil || !strings.Contains(why.Error(), "no renewal was made within the key's age") {
+		t.Fatalf("a lost the lease for %v", why)
+	}
+	if _, err := a.Epoch(); !errors.Is(err, ErrNotHeld) {
+		t.Fatalf("a acts after losing the lease: %v", err)
+	}
+}
+
+func TestARenewalMadeAfterAStallOpensTheGateAgain(t *testing.T) {
+	_, bucket := aBucket(t)
+	a := aController(t, bucket, "a", nil)
+	bus := stallable(a, false)
+	epoch := keeping(t, a)
+	bus.Store(true)
+
+	stalled := time.Now()
+	for a.Held() {
+		if time.Since(stalled) > testTTL {
+			t.Fatal("a still starts acts a whole key's age into a stall")
+		}
+		time.Sleep(20 * time.Millisecond)
+	}
+	bus.Store(false)
+	for !a.Held() {
+		select {
+		case <-a.Lost():
+			t.Fatalf("a lost the lease to a stall shorter than the key's age: %v", a.LostWhy())
+		default:
+		}
+		if time.Since(stalled) > 2*testTTL {
+			t.Fatal("a never acted again after the bus answered")
+		}
+		time.Sleep(20 * time.Millisecond)
+	}
+	if e, err := a.Epoch(); err != nil || e != epoch {
+		t.Fatalf("a acts again as %d, %v; it held epoch %d", e, err, epoch)
+	}
+	// And keeps it, renewing, across more than one age of the key.
+	time.Sleep(testTTL + testRenew)
+	if !a.Held() {
+		t.Fatalf("a stopped acting after the stall ended: %v", a.LostWhy())
+	}
+}
+
+func TestARenewalWrittenThoughItsAnswerWasLostIsStillTheHolders(t *testing.T) {
+	_, bucket := aBucket(t)
+	a := aController(t, bucket, "a", nil)
+	bus := stallable(a, true)
+	epoch := keeping(t, a)
+	// The bus writes each renewal and its answer never arrives: the key moves past the revision a
+	// knows, and is still a's.
+	bus.Store(true)
+	stalled := time.Now()
+	for a.Held() {
+		if time.Since(stalled) > testTTL {
+			t.Fatal("a still starts acts a whole key's age into a stall")
+		}
+		time.Sleep(20 * time.Millisecond)
+	}
+	bus.Store(false)
+	deadline := time.Now().Add(2 * testRenew)
+	for !a.Held() {
+		select {
+		case <-a.Lost():
+			t.Fatalf("a lost the lease to its own renewal: %v", a.LostWhy())
+		default:
+		}
+		if time.Now().After(deadline) {
+			t.Fatal("a never renewed over the renewal the stall wrote")
+		}
+		time.Sleep(20 * time.Millisecond)
+	}
+	h, found, err := a.Current(t.Context())
+	if err != nil || !found || h.Instance != "a" || h.Epoch != epoch {
+		t.Fatalf("the key says %+v (%v, %v), want a at epoch %d", h, found, err, epoch)
+	}
+}
+
+func TestAnotherHolderSeenAfterAStallIsALossAtOnce(t *testing.T) {
+	js, bucket := aBucket(t)
+	a := aController(t, bucket, "a", nil)
+	bus := stallable(a, false)
+	keeping(t, a)
+	bus.Store(true)
+	time.Sleep(testRenew + testRenew/2)
+	// While a's renewals go unanswered, somebody else writes the key.
+	kv, err := js.KeyValue(t.Context(), bucket)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, err := kv.Put(t.Context(), Key, []byte(`{"instance":"b","epoch":1}`)); err != nil {
+		t.Fatal(err)
+	}
+	bus.Store(false)
+	renewed := a.Renewed()
+	select {
+	case <-a.Lost():
+		if lostAt := time.Since(renewed); lostAt >= testTTL {
+			t.Fatalf("a was told it lost the lease only %s after its last renewal: another holder is a loss at once", lostAt)
+		}
+	case <-time.After(testTTL):
+		t.Fatal("a was not told another controller holds the lease")
+	}
+	if why := a.LostWhy(); why == nil || !strings.Contains(why.Error(), "another holder") {
+		t.Fatalf("a lost the lease for %v", why)
+	}
+}

internal/link/advisories.go

@@ -24,9 +24,10 @@ import (
 // which consumer of whose, which subject — for the watchdog to say as a condition, as the refused
 // reply of issue 265 is said today.
 //
-// What the bus says about **other** principals' connections — a module's slow consumer, a module
+// What the bus does to **other** principals' connections the server does not publish in the mesh's
-// refused a subject — the server publishes only to a system account, which the mesh's bus does not
+// account. A module's slow consumer it closes and records, and the bus module says that record on the
-// have; that half is not heard yet (to-be 45 S9, recorded as deferred).
+// bus (busfaults.go, novox/hq ADR 0357). A module refused a subject is told and written in the server's
+// log, and nowhere else: not heard yet (novox/hq issue 702).
 
 // The advisory kinds, as conditions name them.
 const (
@@ -48,6 +49,11 @@ type Advisory struct {
 	Stream, Consumer string
 	// Token is the condition key's last part, when it is not Kind.
 	Token string
+	// User is the bus user whose connection it is about, when it is about one (novox/hq ADR 0357): the
+	// controller's own, or another user's the bus module said.
+	User string
+	// Reason is the server's reason for closing that connection, as it gave it.
+	Reason string
 	// Said is the newest saying, in the mesh's words.
 	Said        string
 	First, Last time.Time

internal/link/build.go

@@ -116,9 +116,21 @@ type ReuseAsk struct {
 type CheckedBuild struct {
 	Pull  PullRef `json:"pull"`
 	Check string  `json:"check"`
+	// Head is the pull request's head the check judged, as its verdict says it (twelve characters): a build is
+	// taken or kept only by a check of the same head (novox/hq issue 703).
+	Head  string     `json:"head,omitempty"`
 	Built CheckBuilt `json:"built"`
 }
 
+// SameHead says two spellings of a commit name the same one: both said, one the other's beginning, at least
+// twelve characters of it (a verdict says twelve).
+func SameHead(a, b string) bool {
+	if len(a) > len(b) {
+		a, b = b, a
+	}
+	return len(a) >= 12 && strings.HasPrefix(b, a)
+}
+
 // PullRef names a pull request.
 type PullRef struct {
 	Owner  string `json:"owner"`
@@ -164,6 +176,35 @@ type CheckRequest struct {
 	// each, from the merge it judged, into the scratch namespace once it has judged and not failed, for the walk to
 	// take. A build seat from before it builds nothing, and the walk builds as before.
 	Builds []CheckBuild `json:"builds,omitempty"`
+	// Named are the builds the seat's verdicts of earlier checks of this pull request at this head name, within the
+	// week check builds are kept (novox/hq issue 703): asked again because only the trunk moved, the check keeps a
+	// build kept under a module's unchanged key, instead of building it again, only when one of these names its key
+	// and every digest. Never another pull request's, nor an earlier head's. A build seat from before it builds.
+	Named []CheckedBuild `json:"named,omitempty"`
+	// Try marks a branch tried before its pull request (novox/hq issue 686): the repository's own check for a
+	// pushed branch or commit, asked by a builder through the controller's `try` verb. Its outcome is read from
+	// the build's log (StepTried) and said to nobody: no status on the forge, nothing recorded or registered,
+	// nothing built for a merge. Tests narrows what the repository's script runs to the tests a pattern names,
+	// and StoreOnly to its store tests; a script that reads neither runs whole.
+	Try       bool   `json:"try,omitempty"`
+	Tests     string `json:"tests,omitempty"`
+	StoreOnly bool   `json:"store-only,omitempty"`
+}
+
+// StepTried is the step a build seat says a try's outcome under, in the build's log: one line, a Tried as JSON
+// (novox/hq issue 686).
+const StepTried = "tried"
+
+// Tried is what came of a branch tried before its pull request (novox/hq issue 686): the verdict of the
+// repository's own check for the ref merged into the trunk, how long it took, and the lines that name what
+// failed, picked from the whole of its output (issue 460).
+type Tried struct {
+	Verdict string   `json:"verdict"`
+	Summary string   `json:"summary"`
+	Took    string   `json:"took"`
+	Head    string   `json:"head,omitempty"`
+	Trunk   string   `json:"trunk,omitempty"`
+	Failed  []string `json:"failed,omitempty"`
 }
 
 // CheckBuild is one module a check builds for its merge: from the merge it made when Merged — a module built from
@@ -188,6 +229,9 @@ type CheckBuilt struct {
 	Made     []MadeArtifact `json:"made,omitempty"`
 	NotBuilt string         `json:"not-built,omitempty"`
 	Took     string         `json:"took,omitempty"`
+	// Kept names the check whose build this check kept instead of building, its key unchanged (novox/hq issue 703):
+	// a walk takes it as that check's build. Empty when this check built it.
+	Kept string `json:"kept,omitempty"`
 }
 
 // GroupMember is one other head of a delivery group's composed check.

internal/link/builds.go

@@ -96,8 +96,27 @@ type BuildStart struct {
 	// an earlier taker left unfinished — most often a build agent replaced mid-build — and started
 	// again from the beginning (novox/hq issue 594). 0 from a machine that predates it.
 	Delivery int `json:"delivery,omitempty"`
+	// Try marks the start of a branch tried before its pull request (novox/hq issue 686), which names no
+	// repository and no ref (startOf).
+	Try bool `json:"try,omitempty"`
 }
 
+// startOf is what a build machine says of the ask it took. **A try's start names no repository and no commit**
+// (novox/hq issue 686): the forge's holder writes mesh/merge-gate pending on an open pull request whose head is
+// the commit a start names, and a try of that head is no check of the pull request — nothing on the forge moves
+// for a try. Its id, machine and time are all the queue reads of a start.
+func startOf(r BuildRequest, on string, delivery int, at time.Time) BuildStart {
+	s := BuildStart{ID: r.ID, Repository: r.Repository, Path: r.Path, Ref: r.Ref, On: on,
+		At: at.UTC().Format(time.RFC3339Nano), Delivery: delivery}
+	if IsTry(r) {
+		s.Repository, s.Path, s.Ref, s.Try = "", "", "", true
+	}
+	return s
+}
+
+// IsTry says an ask is a branch tried before its pull request (novox/hq issue 686).
+func IsTry(r BuildRequest) bool { return r.Check != nil && r.Check.Try }
+
 // Restarted is how a build handed out again says so (novox/hq issue 594), in its log and in its check's
 // report, so a second run never reads as the first. Neutral on why: a holder replaced mid-build, a paused
 // holder handing an ask back as it arrived, and a bus that held its acknowledgements past the wait all

internal/link/builds_nats.go

@@ -401,10 +401,7 @@ func (b *natsBuild) Done() error { return b.msg.Ack() }
 // Began publishes that this machine has taken the build, into the stream like the outcome, so a
 // reader that asks afterwards sees when it started as well as how it ended.
 func (b *natsBuild) Began(ctx context.Context) error {
-	body, err := json.Marshal(BuildStart{
+	body, err := json.Marshal(startOf(b.request, b.on, b.delivery, time.Now()))
-		ID: b.request.ID, Repository: b.request.Repository, Path: b.request.Path,
-		Ref: b.request.Ref, On: b.on, At: time.Now().UTC().Format(time.RFC3339Nano), Delivery: b.delivery,
-	})
 	if err != nil {
 		return err
 	}

internal/link/busfaults.go

@@ -0,0 +1,235 @@
+package link
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"sort"
+	"time"
+
+	"github.com/nats-io/nats.go"
+
+	"github.com/novox/mesh-controller/internal/broker"
+)
+
+// What the bus did to other users' connections, as the bus module says it (novox/hq ADR 0357, issue 270).
+//
+// **The server says another user's slow consumer only in its record of closed connections**, which the
+// bus module reads on its own machine and says as events: `bus.slow-consumer` for a connection the server
+// closed as a slow consumer, `bus.connection-closed` for one it closed for breaking the bus's rules. They
+// are read back from EVENTS on every watchdog tick for the hour S9 says an advisory, rather than taken by
+// the controller's durable consumer: that one takes a message at a time while a merge builds for
+// minutes, and read back, a controller that restarts says the last hour again without keeping anything.
+//
+// **Said at least once, counted once.** The module says the last hour again whenever it starts; a closure
+// is its user, its connection id and when it opened, and is counted once however often it is said.
+
+// BusModule is the module whose events say what the bus did to its users' connections.
+const BusModule = "nats"
+
+// The bus module's events, by their local names (its manifest's `emits`).
+const (
+	BusSlowConsumerEvent     = "bus.slow-consumer"
+	BusConnectionClosedEvent = "bus.connection-closed"
+)
+
+// AdvisoryConnectionClosed is a connection the bus closed for breaking its rules, as conditions name it.
+const AdvisoryConnectionClosed = "connection-closed"
+
+// BusClosure is one closed connection as the bus module says it: the user, never a credential.
+type BusClosure struct {
+	User    string    `json:"user"`
+	Name    string    `json:"name,omitempty"`
+	CID     uint64    `json:"cid"`
+	Reason  string    `json:"reason"`
+	Opened  time.Time `json:"opened"`
+	Closed  time.Time `json:"closed"`
+	Pending int64     `json:"pending_bytes,omitempty"`
+}
+
+func (c BusClosure) identity() string {
+	return fmt.Sprintf("%s/%d/%s", c.User, c.CID, c.Opened.UTC().Format(time.RFC3339Nano))
+}
+
+// BusClosures are the advisories the bus module's closures make, closed at or after since: one per user
+// and kind, each closure counted once, the newest said.
+func BusClosures(closures []BusClosure, kinds []string, since time.Time) []Advisory {
+	type entry struct {
+		a      *Advisory
+		seen   map[string]bool
+		newest BusClosure
+	}
+	by := map[string]*entry{}
+	var order []string
+	for i, c := range closures {
+		if c.User == "" || c.Closed.Before(since) {
+			continue
+		}
+		kind := kinds[i]
+		key := kind + "/" + c.User
+		e := by[key]
+		if e == nil {
+			e = &entry{a: &Advisory{Kind: kind, ID: c.User, User: c.User}, seen: map[string]bool{}}
+			by[key] = e
+			order = append(order, key)
+		}
+		if e.seen[c.identity()] {
+			continue
+		}
+		e.seen[c.identity()] = true
+		e.a.Count++
+		if e.a.First.IsZero() || c.Closed.Before(e.a.First) {
+			e.a.First = c.Closed
+		}
+		if !c.Closed.Before(e.a.Last) {
+			e.a.Last, e.newest = c.Closed, c
+		}
+	}
+	sort.Strings(order)
+	out := make([]Advisory, 0, len(order))
+	for _, key := range order {
+		e := by[key]
+		c := e.newest
+		name := ""
+		if c.Name != "" && c.Name != c.User {
+			name = fmt.Sprintf(" (connection %q)", c.Name)
+		}
+		pending := ""
+		if c.Pending > 0 {
+			pending = fmt.Sprintf(", %d bytes still to be written to it", c.Pending)
+		}
+		switch e.a.Kind {
+		case AdvisorySlowConsumer:
+			e.a.Said = fmt.Sprintf("the bus closed %s's connection %d%s as a slow consumer: %s%s", c.User, c.CID,
+				name, c.Reason, pending)
+		default:
+			e.a.Said = fmt.Sprintf("the bus closed %s's connection %d%s: %s", c.User, c.CID, name, c.Reason)
+		}
+		e.a.Reason = c.Reason
+		out = append(out, *e.a)
+	}
+	return out
+}
+
+// busEventKind is the advisory kind of one of the bus module's events, by its subject.
+func busEventKind(subject string) (string, bool) {
+	switch subject {
+	case EventSubject(BusModule, BusSlowConsumerEvent):
+		return AdvisorySlowConsumer, true
+	case EventSubject(BusModule, BusConnectionClosedEvent):
+		return AdvisoryConnectionClosed, true
+	}
+	return "", false
+}
+
+// BusFaults reads back what the bus module said of its users' connections since a moment, from the events
+// stream, on a consumer of its own that acknowledges nothing (as PowerStates reads), and says it as
+// advisories. Nothing to read is no advisory, and costs two direct reads: the newest of each event.
+func (s *Server) BusFaults(ctx context.Context, since time.Time) ([]Advisory, error) {
+	if s.js == nil {
+		return nil, errors.New("this control plane is not on the bus, so it cannot read what the bus module said")
+	}
+	js := s.js.Context()
+	recent := false
+	for _, event := range []string{BusSlowConsumerEvent, BusConnectionClosedEvent} {
+		last, err := js.GetLastMsg(broker.EventsStream, EventSubject(BusModule, event), nats.Context(ctx))
+		if errors.Is(err, nats.ErrMsgNotFound) {
+			continue
+		}
+		if err != nil {
+			return nil, fmt.Errorf("reading what the bus module said of its users' connections: %w", err)
+		}
+		if !last.Time.Before(since) {
+			recent = true
+		}
+	}
+	if !recent {
+		return nil, nil
+	}
+	sub, err := js.SubscribeSync(EventSubject(BusModule, "bus.>"), nats.OrderedConsumer(), nats.StartTime(since))
+	if err != nil {
+		return nil, fmt.Errorf("reading what the bus module said of its users' connections: %w", err)
+	}
+	defer func() { _ = sub.Unsubscribe() }()
+	var closures []BusClosure
+	var kinds []string
+	read, cut := 0, false
+	for {
+		if read >= MaxBusEventsRead {
+			cut = true
+			break
+		}
+		read++
+		wait, cancel := context.WithTimeout(ctx, readQuiet)
+		msg, err := sub.NextMsgWithContext(wait)
+		cancel()
+		if err != nil {
+			if ctx.Err() != nil {
+				return nil, ctx.Err()
+			}
+			break
+		}
+		if kind, ok := busEventKind(msg.Subject); ok {
+			var c BusClosure
+			if json.Unmarshal(msg.Data, &c) == nil && c.User != "" && !c.Closed.IsZero() {
+				closures, kinds = append(closures, c), append(kinds, kind)
+			}
+		}
+		if meta, err := msg.Metadata(); err != nil || meta.NumPending == 0 {
+			break
+		}
+	}
+	out := BusClosures(closures, kinds, since)
+	if cut {
+		// Said, never silent: a busy hour is read up to the bound, and each advisory says it is a floor.
+		for i := range out {
+			out[i].Said += fmt.Sprintf(" (at least: the read stopped at %d of the bus module's events this hour)",
+				MaxBusEventsRead)
+		}
+	}
+	return out, nil
+}
+
+// MaxBusEventsRead bounds one tick's read of the bus module's events: a watchdog tick must not spend itself
+// reading a storm of closures back. A read cut there says so in every advisory it makes.
+var MaxBusEventsRead = 2000
+
+// MergeAdvisories is two lists of advisories as one: the same kind about the same thing is one advisory,
+// counted once (the larger count of the two), said by the newer. The controller's own slow consumer as its client library sees it and
+// as the server closed it are the same user's (`controller`).
+func MergeAdvisories(a, b []Advisory) []Advisory {
+	out := append([]Advisory(nil), a...)
+	at := map[string]int{}
+	for i, x := range out {
+		at[x.Kind+"/"+x.ID+"/"+x.Token] = i
+	}
+	for _, y := range b {
+		key := y.Kind + "/" + y.ID + "/" + y.Token
+		i, had := at[key]
+		if !had {
+			at[key] = len(out)
+			out = append(out, y)
+			continue
+		}
+		x := &out[i]
+		// The same fault seen twice, not two faults: the controller's own slow consumer is told to its client
+		// library and closed by the server, and is counted once — by whichever saw more of it.
+		if y.Count > x.Count {
+			x.Count = y.Count
+		}
+		if y.First.Before(x.First) {
+			x.First = y.First
+		}
+		if y.Last.After(x.Last) {
+			x.Last, x.Said = y.Last, y.Said
+			if y.Reason != "" {
+				x.Reason = y.Reason
+			}
+		}
+		if x.User == "" {
+			x.User = y.User
+		}
+	}
+	return out
+}

internal/link/busfaults_test.go

@@ -0,0 +1,121 @@
+package link
+
+import (
+	"encoding/json"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/novox/mesh-controller/internal/broker"
+	"github.com/novox/mesh-controller/internal/testbus"
+)
+
+// What the bus module says of its users' connections, read back as advisories (novox/hq ADR 0357, issue
+// 270): one per user and kind, each closure counted once however often it is said.
+//
+//	go test ./internal/link/ -run TestNatsBusFaults   (each test on a bus of its own: internal/testbus)
+
+func aBusWithEvents(t *testing.T) *Server {
+	t.Helper()
+	js, err := broker.Dial(testbus.URL(t))
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(js.Close)
+	if err := broker.AssertMeshStreams(js); err != nil {
+		t.Fatal(err)
+	}
+	return ConnectNats(js, nil, nil)
+}
+
+func sayClosure(t *testing.T, s *Server, event string, c BusClosure) {
+	t.Helper()
+	body, _ := json.Marshal(c)
+	if _, err := s.js.Context().Publish(EventSubject(BusModule, event), body); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestNatsBusFaultsAreOnePerUserAndKindEachClosureCountedOnce(t *testing.T) {
+	s := aBusWithEvents(t)
+	now := time.Now().UTC()
+	slow := BusClosure{User: "laptop.claude-code", Name: "laptop.claude-code", CID: 10, Reason: "Slow Consumer (Write Deadline)",
+		Opened: now.Add(-20 * time.Minute), Closed: now.Add(-2 * time.Minute), Pending: 334000}
+	sayClosure(t, s, BusSlowConsumerEvent, slow)
+	sayClosure(t, s, BusSlowConsumerEvent, slow) // said again: the module started again
+	again := slow
+	again.CID, again.Opened, again.Closed = 31, now.Add(-90*time.Second), now.Add(-time.Minute)
+	sayClosure(t, s, BusSlowConsumerEvent, again)
+	sayClosure(t, s, BusConnectionClosedEvent, BusClosure{User: "anchor.desk", CID: 7,
+		Reason: "Maximum Message Payload Exceeded", Opened: now.Add(-time.Hour / 2), Closed: now.Add(-30 * time.Second)})
+	// Older than the hour: S9 no longer says it.
+	sayClosure(t, s, BusSlowConsumerEvent, BusClosure{User: "anchor.media", CID: 3, Reason: "Slow Consumer (Pending Bytes)",
+		Opened: now.Add(-3 * time.Hour), Closed: now.Add(-2 * time.Hour)})
+
+	got, err := s.BusFaults(t.Context(), now.Add(-time.Hour))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(got) != 2 {
+		t.Fatalf("read %d advisories, want one for each user within the hour: %+v", len(got), got)
+	}
+	for _, a := range got {
+		switch a.User {
+		case "laptop.claude-code":
+			if a.Kind != AdvisorySlowConsumer || a.ID != "laptop.claude-code" || a.Count != 2 ||
+				!a.Last.Equal(again.Closed) || !a.First.Equal(slow.Closed) || !strings.Contains(a.Said, "connection 31") {
+				t.Errorf("the slow consumer read as %+v: two closures, the one said twice counted once", a)
+			}
+		case "anchor.desk":
+			if a.Kind != AdvisoryConnectionClosed || a.Count != 1 || a.Reason != "Maximum Message Payload Exceeded" {
+				t.Errorf("the closed connection read as %+v", a)
+			}
+		default:
+			t.Errorf("an advisory for %s", a.User)
+		}
+	}
+}
+
+func TestNatsBusFaultsReadNothingWhenTheBusModuleSaidNothing(t *testing.T) {
+	s := aBusWithEvents(t)
+	started := time.Now()
+	got, err := s.BusFaults(t.Context(), time.Now().Add(-time.Hour))
+	if err != nil || len(got) != 0 {
+		t.Fatalf("read %v, %v from a stream the bus module never wrote", got, err)
+	}
+	if took := time.Since(started); took > time.Second {
+		t.Fatalf("reading nothing took %s: a tick must not wait on an empty stream", took)
+	}
+}
+
+func TestTheControllersOwnSlowConsumerAndItsClosedConnectionAreOneAdvisory(t *testing.T) {
+	at := time.Date(2026, 10, 14, 12, 0, 0, 0, time.UTC)
+	own := []Advisory{{Kind: AdvisorySlowConsumer, ID: "controller", Said: "the controller fell behind", First: at, Last: at, Count: 1}}
+	closed := BusClosures([]BusClosure{{User: "controller", CID: 5, Reason: "Slow Consumer (Pending Bytes)",
+		Opened: at.Add(-time.Hour), Closed: at.Add(time.Minute)}}, []string{AdvisorySlowConsumer}, at.Add(-time.Hour))
+	got := MergeAdvisories(own, closed)
+	if len(got) != 1 || got[0].Count != 1 || !got[0].Last.Equal(at.Add(time.Minute)) || got[0].User != "controller" {
+		t.Fatalf("merged as %+v: one fall behind, told to the client and closed by the server, is counted once", got)
+	}
+}
+
+// **A busy hour is read up to a bound, and says it was cut** (review of #326): a storm of closures must not
+// spend a watchdog tick, and a count cut short is a floor, said as one.
+func TestNatsBusFaultsReadAtMostTheBoundAndSaySo(t *testing.T) {
+	s := aBusWithEvents(t)
+	was := MaxBusEventsRead
+	MaxBusEventsRead = 2
+	t.Cleanup(func() { MaxBusEventsRead = was })
+	now := time.Now().UTC()
+	for i := range 3 {
+		sayClosure(t, s, BusSlowConsumerEvent, BusClosure{User: "laptop.claude-code", CID: uint64(10 + i),
+			Reason: "Slow Consumer (Pending Bytes)", Opened: now.Add(-time.Hour / 2), Closed: now.Add(-time.Duration(3-i) * time.Minute)})
+	}
+	got, err := s.BusFaults(t.Context(), now.Add(-time.Hour))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(got) != 1 || got[0].Count != 2 || !strings.Contains(got[0].Said, "at least: the read stopped at 2") {
+		t.Fatalf("a read past its bound read as %+v", got)
+	}
+}

internal/link/check_builds_test.go

@@ -37,3 +37,51 @@ func TestNatsTheBuildsAWalkMayTakeAreTheChecksOutcomesOfItsPullRequests(t *testi
 		t.Fatalf("read %+v", got)
 	}
 }
+
+// A build is read with the head its check judged, and a kept build is named as the check's that built it (novox/hq
+// issue 703).
+func TestNatsAKeptBuildIsTheBuildersCheckAndEveryBuildSaysItsHead(t *testing.T) {
+	js := aBus(t)
+	since := time.Now().Add(-time.Minute)
+	say := func(r BuildResult) {
+		body, _ := json.Marshal(r)
+		if _, err := js.Context().Publish(BuildOutcomeOf(TheBuildMachine), body); err != nil {
+			t.Fatal(err)
+		}
+	}
+	mine := &CheckRequest{Owner: "novox", Repo: "shop", Number: 7}
+	app := CheckBuilt{Module: "app", Key: "r1:1", Made: []MadeArtifact{{Name: "server", Reference: "s/app/server@sha256:a"}}}
+	say(BuildResult{ID: "build-1", Checked: mine, Check: &CheckOutcome{Verdict: "pass", Head: "aaaaaaaaaaaa",
+		Built: []CheckBuilt{app}}})
+	kept := app
+	kept.Kept = "build-1"
+	say(BuildResult{ID: "build-2", Checked: mine, Check: &CheckOutcome{Verdict: "pass", Head: "aaaaaaaaaaaa",
+		Built: []CheckBuilt{kept}}})
+
+	got, err := ReadCheckBuilds(t.Context(), js, TheBuildMachine, []PullRef{{Owner: "novox", Repo: "shop", Number: 7}}, since)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(got) != 2 || got[0].Check != "build-1" || got[0].Built.Kept != "build-1" || got[0].Head != "aaaaaaaaaaaa" ||
+		got[1].Check != "build-1" || got[1].Head != "aaaaaaaaaaaa" {
+		t.Fatalf("read %+v", got)
+	}
+}
+
+// Two spellings of a head are the same head only when both say at least twelve characters of it.
+func TestSameHeadNeedsTwelveCharactersOfBoth(t *testing.T) {
+	for _, c := range []struct {
+		a, b string
+		same bool
+	}{
+		{"aaaaaaaaaaaa", "aaaaaaaaaaaabbbb", true},
+		{"aaaaaaaaaaaabbbb", "aaaaaaaaaaaa", true},
+		{"aaaaaaaaaaaa", "aaaaaaaaaaab", false},
+		{"", "", false},
+		{"aaaa", "aaaaaaaaaaaa", false},
+	} {
+		if SameHead(c.a, c.b) != c.same {
+			t.Errorf("SameHead(%q, %q) is %v", c.a, c.b, !c.same)
+		}
+	}
+}

internal/link/events.go

@@ -176,6 +176,9 @@ type SourceMoved struct {
 	Repo  string `json:"repo"`
 	Base  string `json:"base"`
 	Head  string `json:"head"`
+	// HeadSHA is the head commit the forge merged (novox/hq issue 703): a walk takes only a build a check of that
+	// head made. Empty from a forge module from before it, and then the walk takes no check's build.
+	HeadSHA  string `json:"head_sha,omitempty"`
 	Commit   string `json:"merge_commit_sha"`
 	CloneURL string `json:"clone_url"`
 	HTMLURL  string `json:"html_url"`

internal/link/queue.go

@@ -375,6 +375,13 @@ func ReadCheckBuilds(ctx context.Context, js *broker.JetStream, seat string, pul
 	for _, p := range pulls {
 		wanted[p] = true
 	}
+	return readCheckBuilds(ctx, js, seat, since, func(p PullRef, _ CheckBuilt) bool { return wanted[p] })
+}
+
+// readCheckBuilds is every build the seat's checks said they made, or kept, that wanted takes. A kept build is named
+// as the check's that built it (novox/hq issue 703): the record under its key is that check's.
+func readCheckBuilds(ctx context.Context, js *broker.JetStream, seat string, since time.Time,
+	wanted func(PullRef, CheckBuilt) bool) ([]CheckedBuild, error) {
 	subject := BuildOutcomeOf(seat)
 	sub, err := js.Context().PullSubscribe(subject, "",
 		nats.BindStream(broker.EventsStream), nats.StartTime(since), nats.AckNone())
@@ -402,12 +409,13 @@ func ReadCheckBuilds(ctx context.Context, js *broker.JetStream, seat string, pul
 				continue
 			}
 			pull := PullRef{Owner: r.Checked.Owner, Repo: r.Checked.Repo, Number: r.Checked.Number}
-			if !wanted[pull] {
-				continue
-			}
 			for _, b := range r.Check.Built {
-				if b.NotBuilt == "" && b.Key != "" {
+				if b.NotBuilt == "" && b.Key != "" && wanted(pull, b) {
-					out = append(out, CheckedBuild{Pull: pull, Check: r.ID, Built: b})
+					check := r.ID
+					if b.Kept != "" {
+						check = b.Kept
+					}
+					out = append(out, CheckedBuild{Pull: pull, Check: check, Head: r.Check.Head, Built: b})
 				}
 			}
 		}
@@ -427,6 +435,9 @@ func ReadCheckBuilds(ctx context.Context, js *broker.JetStream, seat string, pul
 // safeKey is an id that can be a key, and a subject token, as it is: a build id, never a pattern.
 var safeKey = regexp.MustCompile(`^[A-Za-z0-9_-]+$`)
 
+// SafeBuildID says an id can be a subject token as it is: a build's id, never a pattern.
+func SafeBuildID(id string) bool { return safeKey.MatchString(id) }
+
 // Cancelled is what the controller writes for an ask it cancelled.
 type Cancelled struct {
 	At  string `json:"at"`

internal/link/queue_order.go

@@ -26,6 +26,8 @@ import (
 //   - a check that has waited CheckWaitsAtMost goes before every delivery asked after it, so no check
 //     waits for ever behind a stream of deliveries;
 //   - within a kind, first come, first served, by when it was asked;
+//   - a branch tried before its pull request goes after everything else, however long it has waited: it is
+//     never promoted ahead of a delivery, and never ahead of a pull request's check (novox/hq issue 686);
 //   - an ask whose kind cannot be told counts as a check: a delivery taken late breaks a budget, a check
 //     taken late breaks nothing.
 //
@@ -64,8 +66,12 @@ func (a QueuedAsk) askedOrStored() time.Time {
 // QueueOrder is the order the waiting asks are to be handed out in, now: the deliveries and every check
 // that has waited CheckWaitsAtMost, by when each was asked, then the other checks, by when each was asked.
 func QueueOrder(waiting []QueuedAsk, now time.Time) []QueuedAsk {
-	var first, then []QueuedAsk
+	var first, then, tries []QueuedAsk
 	for _, a := range waiting {
+		if IsTry(a.Request) {
+			tries = append(tries, a)
+			continue
+		}
 		if KindOf(a.Request) == KindCheck && now.Sub(a.askedOrStored()) < CheckWaitsAtMost {
 			then = append(then, a)
 			continue
@@ -82,7 +88,8 @@ func QueueOrder(waiting []QueuedAsk, now time.Time) []QueuedAsk {
 	}
 	byAsking(first)
 	byAsking(then)
-	return append(first, then...)
+	byAsking(tries)
+	return append(append(first, then...), tries...)
 }
 
 // toMove is the asks to move to the tail, in this order, for the queue to stand as order says: everything

internal/link/try_test.go

@@ -0,0 +1,55 @@
+package link
+
+import (
+	"encoding/json"
+	"reflect"
+	"strings"
+	"testing"
+	"time"
+)
+
+// The start of a try names no repository and no commit (novox/hq issue 686): the forge's holder writes
+// mesh/merge-gate pending on the open pull request whose head a start names, and nothing on the forge moves
+// for a try. A pull request's check still names both.
+func TestATrysStartNamesNoCommitTheForgeCouldMatch(t *testing.T) {
+	sha := strings.Repeat("c0ffee", 7)[:40]
+	at := time.Date(2026, 10, 14, 0, 0, 0, 0, time.UTC)
+	try := BuildRequest{ID: "build-1", Repository: "https://forge/novox/a.git", Ref: sha,
+		Check: &CheckRequest{Owner: "novox", Repo: "a", Try: true}}
+	body, _ := json.Marshal(startOf(try, "ace", 1, at))
+	if strings.Contains(string(body), sha) || strings.Contains(string(body), "novox/a") {
+		t.Fatalf("a try's start names what the forge matches a pull request by: %s", body)
+	}
+	if s := startOf(try, "ace", 2, at); s.ID != "build-1" || s.On != "ace" || !s.Try || s.Delivery != 2 || s.At == "" {
+		t.Fatalf("a try's start lost what the queue reads: %+v", s)
+	}
+	pull := try
+	pull.Check = &CheckRequest{Owner: "novox", Repo: "a", Number: 7}
+	if s := startOf(pull, "ace", 1, at); s.Ref != sha || s.Repository == "" || s.Try {
+		t.Fatalf("a pull request's check's start: %+v", s)
+	}
+}
+
+// A try stays behind every delivery and every pull request's check, however long it has waited: the ten
+// minutes that put a check ahead of later deliveries never promote a try (novox/hq issue 686).
+func TestATryIsNeverHandedOutBeforeADeliveryOrAPullRequestsCheck(t *testing.T) {
+	now := time.Date(2026, 10, 12, 12, 0, 0, 0, time.UTC)
+	try := func(seq uint64, id string, asked time.Time) QueuedAsk {
+		a := anAsk(seq, id, asked, true)
+		a.Request.Check.Try = true
+		return a
+	}
+	waiting := []QueuedAsk{
+		try(1, "try-old", now.Add(-40*time.Minute)),
+		try(2, "try-young", now.Add(-time.Minute)),
+		anAsk(3, "check-young", now.Add(-2*time.Minute), true),
+		anAsk(4, "delivery", now.Add(-time.Minute), false),
+	}
+	want := []string{"delivery", "check-young", "try-old", "try-young"}
+	if got := idsOf(QueueOrder(waiting, now)); !reflect.DeepEqual(got, want) {
+		t.Fatalf("handed out as %v, want %v", got, want)
+	}
+	if !SafeBuildID("build-20261014T000000-1a2b") || SafeBuildID("x.>") || SafeBuildID("*") || SafeBuildID("") {
+		t.Fatal("an id that is a pattern passes for a build's id")
+	}
+}

merge-check.sh

@@ -54,11 +54,26 @@ if [ -n "$unformatted" ]; then
 fi
 CGO_ENABLED=0 go vet ./...
 
-if command -v gcc >/dev/null 2>&1; then
+suite() {
-	CGO_ENABLED=1 go test -race -count=1 -timeout 30m ./...
+	if command -v gcc >/dev/null 2>&1; then
-else
+		CGO_ENABLED=1 go test -race -count=1 -timeout 30m "$@"
+	else
 		echo "NOT RACE-CHECKED: the toolchain holds no C compiler; the suite runs without the race detector"
-	CGO_ENABLED=0 go test -count=1 -timeout 30m ./...
+		CGO_ENABLED=0 go test -count=1 -timeout 30m "$@"
+	fi
+}
+# **A branch tried before its pull request may ask for a part** (novox/hq issue 686): the controller's `try` verb
+# hands MESH_CHECK_TESTS, a `go test -run` pattern, or MESH_CHECK_STORE_ONLY=1. A pull request's merge check is
+# handed neither and always runs whole; a part that passes is said as a part, never as the check.
+if [ -n "${MESH_CHECK_TESTS:-}" ]; then
+	echo "TRIED IN PART: only the tests matching $MESH_CHECK_TESTS, in every package"
+	suite -run "$MESH_CHECK_TESTS" ./...
+	exit 0
+fi
+if [ "${MESH_CHECK_STORE_ONLY:-}" = 1 ]; then
+	echo "TRIED IN PART: only the store tests listed in testdata/store-tests"
+else
+	suite ./...
 fi
 
 # **The store tests listed ran** (novox/hq issue 459): a test that needs the store skips without one, and a skip

module.json

@@ -77,6 +77,7 @@
     "replay",
     "kill",
     "forget-checks",
+    "try",
     "pause",
     "resume",
     "hand-act",

testdata/store-tests

@@ -61,3 +61,14 @@
 ./cmd/mesh-controller TestAProviderElsewhereServesItsOwnComposedName
 ./cmd/mesh-controller TestAReusedCheckBuildIsRegisteredByItsDigestAndGatedAsABuiltOne
 ./internal/inventory TestAReportOfABusyContainerIsKeptAndReadBack
+./cmd/mesh-controller TestAReleaseSendsTheRestAtOnceAfterTheFirstPasses
+./cmd/mesh-controller TestARestMachineThatFailsIsPutBackAloneAndTheOthersAreJudgedOn
+./cmd/mesh-controller TestAWalkTakesOverTheReadingsOfAGateJudgingTheSameBuildThere
+./cmd/mesh-controller TestAFirstSendMadeAndNotKeptIsNotSentAgain
+./cmd/mesh-controller TestAReleaseSendKeptAndMadeIsNotMadeAgain
+./cmd/mesh-controller TestAFirstMachineThatFailsStillStopsTheWalk
+./cmd/mesh-controller TestTheControlNodeIsSentLastInAStep
+./cmd/mesh-controller TestARestMachineSilentPastItsBoundIsLeftAndSaid
+./cmd/mesh-controller TestANoMoveTierWaitsForNoNewReport
+./cmd/mesh-controller TestOneProviderDownAndThreeConsumersFailingAreOneCondition
+./cmd/mesh-controller TestAConsumerFailingBesideAHealthyProviderIsItsOwn