Merge pull request 'A group's check names every member at its head, also one that publishes no package yet (issue 1921)' (#159 ) from fix/1921-zero-pins-own-packages into main

Fold the unpublished-member test into the group member's pins test (test budget, issue 1921)
Claude-Session: https://claude.ai/code/session_01NcbgfFSnn24M3GcqttoU7i
2026-11-05 23:00:43 +00:00 · 2026-11-05 23:44:55 +01:00 · 2026-11-05 23:35:23 +01:00 · 2026-11-05 21:28:43 +00:00 · 2026-11-05 22:15:47 +01:00 · 2026-11-05 21:04:27 +00:00
145 changed files with 8944 additions and 954 deletions
@@ -62,8 +62,6 @@ type fakeBuildModules struct {
 	js        jetstream.JetStream
 	ctx       context.Context
 	failBuild atomic.Bool
-	// failRetakeable makes every build fail as a lookup that timed out (delivery.Retake), which passes by itself.
-	failRetakeable atomic.Bool
 	// refusePush makes every bundle and archive build fail as a push the artifact store refused (ADR 0498 clause 2).
 	refusePush atomic.Bool
 	mu         sync.Mutex
@@ -119,8 +117,6 @@ func (f *fakeBuildModules) step(module, name string, args map[string]any) (any,
 			merge = `,"merge":"` + strings.Repeat("9", 40) + `"`
 		}
 		return json.RawMessage(`{"workspace":"w` + buildstep.NewID() + `","commit":"` + commit + `"` + merge + `}`), nil
-	case f.failRetakeable.Load() && tool != "build_image_copy":
-		return nil, fmt.Errorf("%slookup git.novox.be on 10.10.0.3:53: i/o timeout", delivery.Retake)
 	case f.failBuild.Load() && tool != "build_image_copy": // the build fails wherever it runs
 		return nil, fmt.Errorf("go build of %v: boom", args["artifact"])
 	case tool == "build_image_copy": // the upstream copy answers the digest and the registry's reference (ADR 0498 clause 4)
@@ -495,47 +491,30 @@ func TestAnArchiveOnlyModuleAndARootModuleAreBuilt(t *testing.T) {
 // failed naming it; the indexer writing modules.<m> again with the same fingerprint wakes the builder, which builds
 // the key again as a new revision of the same key, now done.
 func TestAFailedKeyIsBuiltAgainAsANewRevisionFromANewModulesValueWithTheSameFingerprint(t *testing.T) { // 1607/AC6, AC7
-	t.Run("a new modules value with the same fingerprint", func(t *testing.T) {
-		b := startBed(t)
-		b.fake.failBuild.Store(true)
-		b.archive(t, "ca-trust", "modules/ca-trust", commit)
-		b.start(t, "n1", nil)
-		v := b.await(t, "ca-trust", isState(delivery.BuildFailed))
-		if !strings.Contains(v.Error, " on n") || !strings.Contains(v.Error, "boom") {
-			t.Errorf("build = %+v, want failed naming the node and the step's reason", v)
-		}
-		key, _ := delivery.BuilderBuildKey("ca-trust", fp)
-		failed, err := b.builds.Get(b.ctx, key)
-		if err != nil {
-			t.Fatal(err)
-		}
-		b.fake.failBuild.Store(false)
-		// The indexer writes the module again (here at a later commit), with the same fingerprint.
-		b.archive(t, "ca-trust", "modules/ca-trust", "89abcdef0123456789abcdef0123456789abcdef")
-		b.await(t, "ca-trust", isState(delivery.BuildDone))
-		done, err := b.builds.Get(b.ctx, key)
-		if err != nil {
-			t.Fatal(err)
-		}
-		if done.Revision() <= failed.Revision() {
-			t.Errorf("revision %d, was %d: the key was not written as a new revision", done.Revision(), failed.Revision())
-		}
-	})
-	// 1748/AC6: a build failed retakeable is built again after its backoff, with no new modules value or other event, and
-	// ends done; the key says it was retaken.
-	t.Run("a retakeable failure after its backoff", func(t *testing.T) {
-		b := startBed(t)
-		b.fake.failRetakeable.Store(true)
-		b.archive(t, "ca-trust", "modules/ca-trust", commit)
-		b.start(t, "n1", map[string]string{"MESH_BUILDER_RETAKE_BACKOFF": "1s"})
-		if v := b.await(t, "ca-trust", isState(delivery.BuildFailed)); !delivery.Retakeable(v.Error) {
-			t.Fatalf("build = %+v, want failed retakeable", v)
-		}
-		b.fake.failRetakeable.Store(false) // the lookup passes
-		if v := b.await(t, "ca-trust", isState(delivery.BuildDone)); v.Retakes < 1 {
-			t.Errorf("done key = %+v, want its retake counted", v)
-		}
-	})
+	b := startBed(t)
+	b.fake.failBuild.Store(true)
+	b.archive(t, "ca-trust", "modules/ca-trust", commit)
+	b.start(t, "n1", nil)
+	v := b.await(t, "ca-trust", isState(delivery.BuildFailed))
+	if !strings.Contains(v.Error, " on n") || !strings.Contains(v.Error, "boom") {
+		t.Errorf("build = %+v, want failed naming the node and the step's reason", v)
+	}
+	key, _ := delivery.BuilderBuildKey("ca-trust", fp)
+	failed, err := b.builds.Get(b.ctx, key)
+	if err != nil {
+		t.Fatal(err)
+	}
+	b.fake.failBuild.Store(false)
+	// The indexer writes the module again (here at a later commit), with the same fingerprint.
+	b.archive(t, "ca-trust", "modules/ca-trust", "89abcdef0123456789abcdef0123456789abcdef")
+	b.await(t, "ca-trust", isState(delivery.BuildDone))
+	done, err := b.builds.Get(b.ctx, key)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if done.Revision() <= failed.Revision() {
+		t.Errorf("revision %d, was %d: the key was not written as a new revision", done.Revision(), failed.Revision())
+	}
 }

 // TestAToolchainChangeDoesNotBuildTheOldFingerprint: the fingerprint names go1.27.1, the nodes then agree on go1.27.2 (a
@@ -77,12 +77,6 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 			return fmt.Errorf("MESH_BUILDER_STEP_BOUND: %w", err)
 		}
 	}
-	var retakeBackoff time.Duration // 0 is build.DefaultRetakeBackoff
-	if v := strings.TrimSpace(getenv("MESH_BUILDER_RETAKE_BACKOFF")); v != "" {
-		if retakeBackoff, err = time.ParseDuration(v); err != nil {
-			return fmt.Errorf("MESH_BUILDER_RETAKE_BACKOFF: %w", err)
-		}
-	}
 	tools := &buildrun.ToolchainSet{}
 	// Each build module's part of a build is an ask on its build seat's stream, pulled by a build node with a free slot
 	// (novox/hq ADR 0525): the builder chooses no node, so it reads neither presence nor have and holds no capacity.
@@ -127,8 +121,6 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 		Logf:       logger.Printf,
 		Stored:     storedVia(calls.Call),
 		Node:       cred.Node,
-		// A key failed retakeable (delivery.Retake) is taken again by itself after this wait, at most delivery.MaxRetakes times (issue 1748).
-		RetakeBackoff: retakeBackoff,
 	}
 	// A candidate's preview is merged onto the trunk head the indexer previewed it onto: source.main at the candidate's base
 	// revision (the gate's source state). The source's revisions are watched with their history (a direct get of one revision
@@ -3,7 +3,7 @@ module mesh-delivery-builder
 go 1.26.0

 require (
-	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261104214149-0d97c09c49b4
+	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261103221822-85ba0a9a70d8
 	github.com/nats-io/nats-server/v2 v2.11.17
 	github.com/nats-io/nats.go v1.54.0
 )
@@ -1,7 +1,7 @@
 git.novox.be/novox/mesh-catalog/modules/mesh-build-go/buildstep v0.0.0-20261102193506-d221c633799a h1:oxgksCiq272/afXbUION/dxtAS5MPGnmyq6+AZQxmXg=
 git.novox.be/novox/mesh-catalog/modules/mesh-build-go/buildstep v0.0.0-20261102193506-d221c633799a/go.mod h1:kpsX4Pgss5EeuBvel1zWa2ogj7MkR3jZso6oa/J0YUQ=
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261104214149-0d97c09c49b4 h1:K2niszrlnJ7JMiXI6xg4gG90YCd/tqNLGBvujLInI48=
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261104214149-0d97c09c49b4/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261103221822-85ba0a9a70d8 h1:XEbIVImp6yGjA91rp0iZBoDdL5KfamjOuDLwWvqh0hc=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261103221822-85ba0a9a70d8/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op h1:Z/MZK75wC/NSrkgqeNIa7jexam9uWzhLmFTSCPI/kn0=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op/go.mod h1:FQyySiasQQM8735Ddel3MRojmy4dA1IqCeyJ5jmPMbI=
 github.com/google/go-tpm v0.9.8 h1:slArAR9Ft+1ybZu0lBwpSmpwhRXaa85hWtMinMyRAWo=
@@ -66,10 +66,6 @@ type ClaimOptions struct {
 	// done: the store's nightly collector deletes a blob nothing holds, and a key the controller never took in holds
 	// nothing, so a key whose blob is gone is claimed building as a new revision and built again. Nil asks nothing.
 	Stored func(ctx context.Context, references []string) (gone []string, err error)
-	// Retaking is this claim being the builder's backoff taking a retakeable failed key again (Builder.armRetake, issue
-	// 1748): only it adds to BuilderBuild.Retakes, so the cap of delivery.MaxRetakes counts the backoff's own retakes and
-	// not a look another event makes while the backoff waits.
-	Retaking bool
 }

 // StoredReferences are the references of a done build's bundles and archives that name a blob in the artifact store
@@ -157,8 +153,7 @@ func Unreferenced(b delivery.BuilderBuild) bool {
 //   - a failed key is taken again as a new revision of the same key (ADR 0429 clause 18), except one failed for a kind no
 //     builder builds, for an upstream pinned by no digest or a package version taken (delivery.FailedUntilChanged: ADR 0478
 //     clause 2, ADR 0498 clauses 4 and 5) or for digests that differ (buildrun.DigestsDifferPrefix, clause 4),
-//     which wait for another fingerprint (a retakeable failure, delivery.Retakeable, is taken again too; the new
-//     revision keeps Retakes, and counts one more only when it is the backoff's claim, ClaimOptions.Retaking), and one failed for want of an image builder (NoImageBuilderPrefix), which waits for
+//     which wait for another fingerprint, and one failed for want of an image builder (NoImageBuilderPrefix), which waits for
 //     another fingerprint or a node that runs the image build module (ClaimOptions.ImageBuilder);
 //   - a key queued waiting for a package version (Waits) is claimed building as a new revision once that version is
 //     published (ClaimOptions.Published, ADR 0500 clause 6), and not before;
@@ -217,10 +212,6 @@ func (c Claimer) Claim(ctx context.Context, module, fingerprint, manifest string
 	case cur.State == delivery.BuildFailed && strings.HasPrefix(cur.Error, NoImageBuilderPrefix) && (opt.ImageBuilder == nil || !opt.ImageBuilder()):
 		return nil, nil
 	case cur.State == delivery.BuildFailed:
-		building.Retakes = cur.Retakes // the count rides on the key's value, so it survives a restart (issue 1748)
-		if opt.Retaking && delivery.Retakeable(cur.Error) {
-			building.Retakes++
-		}
 		return c.write(ctx, key, building, func(data []byte) (uint64, error) { return c.Store.Update(ctx, key, data, rev) })
 	case cur.State == delivery.BuildQueued && cur.Waits != "":
 		if opt.Published == nil || !opt.Published(cur.Waits) {
@@ -1,179 +0,0 @@
-package build
-
-import (
-	"context"
-	"fmt"
-	"strings"
-	"sync"
-	"testing"
-	"time"
-
-	"git.novox.be/novox/mesh-sdk/go/delivery"
-)
-
-// clock is the builder's fake clock for the retake backoff (issue 1748): After records what is asked and fire runs it.
-type clock struct {
-	mu      sync.Mutex
-	waits   []time.Duration
-	pending []func()
-}
-
-func (c *clock) after(d time.Duration, f func()) func() {
-	c.mu.Lock()
-	defer c.mu.Unlock()
-	c.waits, c.pending = append(c.waits, d), append(c.pending, f)
-	return func() {}
-}
-
-// fire runs every timer set so far, once, and answers how many there were.
-func (c *clock) fire() int {
-	c.mu.Lock()
-	fs := c.pending
-	c.pending = nil
-	c.mu.Unlock()
-	for _, f := range fs {
-		f()
-	}
-	return len(fs)
-}
-
-func retakeRig(t *testing.T) (*rig, *clock) {
-	r := newRig(t, goBundle)
-	c := &clock{}
-	r.b.RetakeBackoff, r.b.After = 10*time.Second, c.after
-	return r, c
-}
-
-const lookupFailure = delivery.Retake + "go mod download: lookup git.novox.be on 10.10.0.3:53: i/o timeout"
-
-// 1748: a key failed retakeable is taken again by the builder's backoff, and only by it counts toward the cap.
-func TestTheBuilderRetakesARetakeableFailure(t *testing.T) {
-	// AC3: claimed again as a new revision after the backoff, with no other event; the count kept on the key stops it after
-	// delivery.MaxRetakes, and a builder that starts again reads the count.
-	t.Run("after its backoff, at most three times", func(t *testing.T) {
-		r, c := retakeRig(t)
-		r.bm.fails["ace/build_go_build"] = lookupFailure
-		v := r.consider(t, "modules/m")
-		if v.State != delivery.BuildFailed || !delivery.Retakeable(v.Error) || v.Retakes != 0 {
-			t.Fatalf("build = %+v, want failed retakeable with no retake yet", v)
-		}
-		if len(c.waits) != 1 || c.waits[0] != 10*time.Second {
-			t.Fatalf("backoffs = %v, want one of 10s", c.waits)
-		}
-		rev := r.st.revs[r.key]
-		for retake := 1; retake <= delivery.MaxRetakes; retake++ {
-			if c.fire() != 1 {
-				t.Fatalf("retake %d: no timer was set", retake)
-			}
-			r.b.Wait()
-			v = valueOf(t, r.st, r.key)
-			if v.Retakes != retake || r.st.revs[r.key] <= rev {
-				t.Fatalf("retake %d: key = %+v at revision %d (was %d)", retake, v, r.st.revs[r.key], rev)
-			}
-			rev = r.st.revs[r.key]
-		}
-		if len(c.pending) != 0 || len(c.waits) != delivery.MaxRetakes || c.waits[1] != 20*time.Second || c.waits[2] != 40*time.Second {
-			t.Fatalf("after %d retakes: %d pending, backoffs %v; want none pending and 10s, 20s, 40s", delivery.MaxRetakes, len(c.pending), c.waits)
-		}
-		if n := len(r.bm.callsOf("build_go_build")); n != 1+delivery.MaxRetakes {
-			t.Errorf("%d builds, want the first and %d retakes", n, delivery.MaxRetakes)
-		}
-		// A builder that starts again reads the count from the key: at the cap it arms nothing, below it the next wait.
-		restarted := func(retakes int) *clock {
-			rr, cc := retakeRig(t)
-			rr.st, rr.b.Claimer.Store = r.st, r.st
-			data, err := delivery.EncodeBuilderBuild(delivery.BuilderBuild{State: delivery.BuildFailed, Error: lookupFailure, Retakes: retakes})
-			if err != nil {
-				t.Fatal(err)
-			}
-			r.st.vals[r.key] = data
-			rr.b.init()
-			rr.b.known["m"] = delivery.Module{FP2: fp1, Manifest: mdigest('a')}
-			if err := rr.b.Sweep(context.Background()); err != nil {
-				t.Fatal(err)
-			}
-			return cc
-		}
-		if cc := restarted(delivery.MaxRetakes); len(cc.waits) != 0 {
-			t.Errorf("a key retaken %d times was armed again: %v", delivery.MaxRetakes, cc.waits)
-		}
-		if cc := restarted(1); len(cc.waits) != 1 || cc.waits[0] != 20*time.Second {
-			t.Errorf("a key retaken once was armed with %v, want one wait of 20s", cc.waits)
-		}
-	})
-	// AC4: a failure of the source (a compile error, FailedUntilChanged) is never taken again by the backoff.
-	t.Run("a failure of the source is never taken again", func(t *testing.T) {
-		for _, reason := range []string{"go build of tool: undefined: x", delivery.NotPinned + "up: names no digest", delivery.VersionTaken + "@x/y@1 holds another file"} {
-			r, c := retakeRig(t)
-			r.bm.fails["ace/build_go_build"] = reason
-			v := r.consider(t, "modules/m")
-			if v.State != delivery.BuildFailed || delivery.Retakeable(v.Error) {
-				t.Fatalf("%q: build = %+v, want failed and not retakeable", reason, v)
-			}
-			if len(c.waits) != 0 || c.fire() != 0 {
-				t.Errorf("%q: the backoff was armed: %v", reason, c.waits)
-			}
-		}
-	})
-	// Only the backoff's claim counts: a look another event makes while the backoff waits (a toolchain change, a new modules
-	// value) takes the key again and leaves the count as it was, so those looks cannot spend the retakes inside the pause.
-	t.Run("another event's look leaves the count", func(t *testing.T) {
-		r, c := retakeRig(t)
-		r.bm.fails["ace/build_go_build"] = lookupFailure
-		r.consider(t, "modules/m")
-		for i := 0; i < 2*delivery.MaxRetakes; i++ {
-			r.b.Reconsider(context.Background())
-			r.b.Wait()
-		}
-		if v := valueOf(t, r.st, r.key); v.Retakes != 0 || v.State != delivery.BuildFailed {
-			t.Fatalf("after Reconsider looks the key = %+v, want failed with Retakes 0", v)
-		}
-		if c.fire() != 1 {
-			t.Fatal("the backoff's own wait was not armed once")
-		}
-		r.b.Wait()
-		if v := valueOf(t, r.st, r.key); v.Retakes != 1 {
-			t.Errorf("after the backoff's claim the key = %+v, want Retakes 1", v)
-		}
-	})
-	// The journal says each retake with its count and the log's entry of the build's end names it.
-	t.Run("the journal and the log say the count", func(t *testing.T) {
-		r, c := retakeRig(t)
-		var said []string
-		r.b.Logf = func(f string, a ...any) { said = append(said, strings.TrimSpace(fmt.Sprintf(f, a...))) }
-		var ended []delivery.BuildLogEntry
-		r.b.Node, r.b.Log = "novox", func(e delivery.BuildLogEntry) {
-			if e.Event == delivery.BuildEndedEvent {
-				ended = append(ended, e)
-			}
-		}
-		r.bm.fails["ace/build_go_build"] = lookupFailure
-		r.consider(t, "modules/m")
-		c.fire()
-		r.b.Wait()
-		if len(ended) != 2 || ended[0].Retakes != 0 || ended[1].Retakes != 1 {
-			t.Fatalf("ended entries = %+v, want retakes 0 then 1; journal: %v", ended, said)
-		}
-		if joined := strings.Join(said, "\n"); !strings.Contains(joined, "taken again after its backoff (retake 1 of 3)") {
-			t.Errorf("the journal says %q, want the retake with its count", joined)
-		}
-	})
-	// The key's error opens with the retake prefix only when every failing lane failed retakeable.
-	t.Run("the key error opens with the prefix only when every lane is retakeable", func(t *testing.T) {
-		for _, c := range []struct {
-			name   string
-			errs   []string
-			prefix bool
-		}{
-			{"one retakeable lane", []string{"mesh-build-go on ace: the step failed: " + lookupFailure}, true},
-			{"two retakeable lanes", []string{"a: " + lookupFailure, "b: " + lookupFailure}, true},
-			{"a retakeable and a compile error", []string{"a: " + lookupFailure, "b: go build of tool: undefined: x"}, false},
-			{"a compile error", []string{"b: go build of tool: undefined: x"}, false},
-		} {
-			got := keyError(c.errs)
-			if has := strings.HasPrefix(got, delivery.Retake); has != c.prefix || delivery.Retakeable(got) != c.prefix {
-				t.Errorf("%s: keyError = %q, want prefix %v", c.name, got, c.prefix)
-			}
-		}
-	})
-}
@@ -79,12 +79,6 @@ type Builder struct {
 	// time.Now. Node is the node the builder runs on, which asked the build.
 	Now  func() time.Time
 	Node string
-	// RetakeBackoff is the wait before the builder takes a key that failed retakeable (delivery.Retakeable) again by itself,
-	// doubled with each retake (issue 1748): DefaultRetakeBackoff when 0. After runs f once d has passed and returns a
-	// stop; nil waits a context's bound (ADR 0437 §8: the builder holds no timer). The wait is re-armed from the key's value at
-	// start (Sweep): a build's work is not a message of the builder's own on a stream, so there is no delivery delay to ride.
-	RetakeBackoff time.Duration
-	After         func(d time.Duration, f func()) (stop func())

 	once     sync.Once
 	sem      chan struct{}
@@ -108,14 +102,8 @@ type Builder struct {
 	waiting map[string]map[string]chan string
 	// hands are the requests to build a key again by hand that wait for the claim and its asks (BuildAgain), by build key.
 	hands map[string]*handWatch
-	// armed are the keys with a retake wait running, by build key; retaking are the keys whose backoff has passed and whose
-	// next claim is the backoff's own (ClaimOptions.Retaking).
-	armed, retaking map[string]bool
 }

-// DefaultRetakeBackoff is the first wait before a retakeable failure is taken again; each retake doubles it.
-const DefaultRetakeBackoff = 60 * time.Second
-
 type planned struct {
 	plan Plan
 	err  error
@@ -132,7 +120,6 @@ func (b *Builder) init() {
 		b.known, b.inflight, b.again, b.plans, b.tried = map[string]delivery.Module{}, map[string]bool{}, map[string]delivery.Module{}, map[string]planned{}, map[string]bool{}
 		b.published, b.held, b.waiting = map[string]bool{}, map[string]bool{}, map[string]map[string]chan string{}
 		b.hands = map[string]*handWatch{}
-		b.armed, b.retaking = map[string]bool{}, map[string]bool{}
 	})
 }

@@ -200,14 +187,6 @@ func (b *Builder) Sweep(ctx context.Context) error {
 			continue
 		}
 		newly = b.notePublished(cur) || newly
-		if current[key] && cur.State == delivery.BuildFailed {
-			if module, _, err := delivery.ParseBuilderBuildKey(key); err == nil {
-				b.mu.Lock()
-				fp := b.known[module].FP2
-				b.mu.Unlock()
-				b.armRetake(ctx, key, module, fp, cur) // a restarted builder reads the count and goes on
-			}
-		}
 		if current[key] || cur.State != delivery.BuildBuilding {
 			continue
 		}
@@ -450,11 +429,9 @@ func (b *Builder) try(ctx context.Context, module string, m delivery.Module) {
 	trunk := b.trunkFP[key]
 	first := !b.tried[key]
 	b.tried[key] = true
-	retaking := b.retaking[key]
-	delete(b.retaking, key)
 	b.mu.Unlock()
 	cl, err := b.Claimer.Claim(ctx, module, m.FP2, m.Manifest, ClaimOptions{TakeOver: first, ImageBuilder: imageSeat, Trunk: trunk, Published: b.isPublished,
-		Stored: b.storedOnce(key), Retaking: retaking})
+		Stored: b.storedOnce(key)})
 	if err != nil {
 		b.logf("%s: %v", module, err)
 		return
@@ -500,7 +477,7 @@ func (b *Builder) try(ctx context.Context, module string, m delivery.Module) {
 		b.logf("%s: left building, the toolchains moved under it", cl.Key)
 		return
 	}
-	result.By, result.Manifest, result.Retakes = b.Claimer.By, m.Manifest, cl.Build.Retakes
+	result.By, result.Manifest = b.Claimer.By, m.Manifest
 	if len(cl.Gone) > 0 && result.State == delivery.BuildDone {
 		result.Step += " (built again: the artifact store no longer held " + strings.Join(cl.Gone, ", ") + ")"
 	}
@@ -516,7 +493,6 @@ func (b *Builder) try(ctx context.Context, module string, m delivery.Module) {
 	b.logBuild(LogEnded(module, m, b.refOf(module, m.FP2), b.Node, b.now(), result))
 	if result.State == delivery.BuildFailed {
 		b.logf("%s: failed: %s", cl.Key, result.Error)
-		b.armRetake(ctx, cl.Key, module, m.FP2, result)
 	}
 	if result.State == delivery.BuildQueued {
 		b.logf("%s: waits for the package %s to be published", cl.Key, result.Waits)
@@ -527,57 +503,6 @@ func (b *Builder) try(ctx context.Context, module string, m delivery.Module) {
 	}
 }

-// armRetake takes a key that failed retakeable again by itself once its backoff has passed, as a new revision (issue 1748):
-// only an error that opens with delivery.Retake, and at most delivery.MaxRetakes times, counted on the key's value. A key
-// failed for its source (a compile error, FailedUntilChanged) is never armed.
-func (b *Builder) armRetake(ctx context.Context, key, module, fp string, v delivery.BuilderBuild) {
-	if v.State != delivery.BuildFailed || !delivery.Retakeable(v.Error) || v.Retakes >= delivery.MaxRetakes || ctx.Err() != nil {
-		return
-	}
-	b.mu.Lock()
-	if b.armed[key] {
-		b.mu.Unlock()
-		return
-	}
-	b.armed[key] = true
-	b.mu.Unlock()
-	wait := b.RetakeBackoff
-	if wait <= 0 {
-		wait = DefaultRetakeBackoff
-	}
-	wait <<= v.Retakes
-	b.logf("%s: failed retakeable; taken again in %s (retake %d of %d)", key, wait, v.Retakes+1, delivery.MaxRetakes)
-	after := b.After
-	if after == nil {
-		// The builder holds no timer (ADR 0437 §8: a wait is a context's bound): the wait is the bound of a context, which
-		// the builder's own context ends early.
-		after = func(d time.Duration, f func()) func() {
-			wait, stop := context.WithTimeout(ctx, d)
-			go func() {
-				<-wait.Done()
-				if errors.Is(wait.Err(), context.DeadlineExceeded) && ctx.Err() == nil {
-					f()
-				}
-			}()
-			return stop
-		}
-	}
-	after(wait, func() {
-		b.mu.Lock()
-		delete(b.armed, key)
-		m, known := b.known[module]
-		b.mu.Unlock()
-		if ctx.Err() != nil || !known || m.FP2 != fp {
-			return // a newer fingerprint supersedes it: that one is built by its own event
-		}
-		b.logf("%s: taken again after its backoff (retake %d of %d)", key, v.Retakes+1, delivery.MaxRetakes)
-		b.mu.Lock()
-		b.retaking[key] = true
-		b.mu.Unlock()
-		b.consider(ctx, module, m)
-	})
-}
-
 // stale is why the module's fingerprint is not built now, or empty when it is: the toolchain each language of the plan
 // has agreed (novox/hq ADR 0465) must be the one the fingerprint was computed with (Module.Toolchains).
 func (b *Builder) stale(m delivery.Module, plan Plan) string {
@@ -799,19 +724,6 @@ func keyError(errs []string) string {
 			}
 		}
 	}
-	// A retakeable failure opens the key's error only when every failing lane is one (issue 1748): a lane that failed on its
-	// source would be built again for nothing.
-	all := len(errs) > 0
-	for _, e := range errs {
-		all = all && strings.Contains(e, delivery.Retake)
-	}
-	if all {
-		stripped := make([]string, len(errs))
-		for i, e := range errs {
-			stripped[i] = strings.Replace(e, delivery.Retake, "", 1)
-		}
-		return delivery.Retake + strings.Join(stripped, "; ")
-	}
 	return strings.Join(errs, "; ")
 }

@@ -1043,7 +955,6 @@ func LogEnded(module string, m delivery.Module, ref, by string, at time.Time, re
 		e.Against = append([]string(nil), m.Inputs2.Bases...)
 	}
 	e.Made = append([]delivery.BuiltArtifact(nil), result.Artifacts...)
-	e.Retakes = result.Retakes
 	e.Imports = append([]string(nil), result.Imports...) // the indexer keeps them on the module (novox/hq ADR 0593 §2)
 	return e
 }
@@ -212,25 +212,4 @@ func TestServesNoRequestSubjectAndHoldsNoTicker(t *testing.T) { // 1607/AC6 (ADR
 	if files < 1 {
 		t.Fatalf("read %d source files, want the program's", files)
 	}
-	// The one bounded wait the builder holds for its own sake is the retake backoff (issue 1748): a goroutine that waits a
-	// context's deadline and then acts. It lives in Builder.armRetake only; any other source holding that idiom is refused.
-	const idiom = "context.DeadlineExceeded"
-	var holders []string
-	for _, root := range []string{"cmd", "internal"} {
-		filepath.WalkDir(root, func(path string, d fs.DirEntry, err error) error {
-			if err != nil || d.IsDir() || !strings.HasSuffix(path, ".go") || strings.HasSuffix(path, "_test.go") {
-				return err
-			}
-			src, _ := os.ReadFile(path)
-			for _, fn := range strings.Split(string(src), "\nfunc ") {
-				if strings.Contains(fn, idiom) && !strings.HasPrefix(fn, "(b *Builder) armRetake(") {
-					holders = append(holders, path)
-				}
-			}
-			return nil
-		})
-	}
-	if len(holders) != 0 {
-		t.Errorf("%v waits for a context's deadline and acts: the retake backoff in Builder.armRetake is the one allowed bounded wait (issue 1748); any other wait is a timer", holders)
-	}
 }
@@ -103,15 +103,25 @@ func TryTools(tr Trying) []stdio.Tool {
 	str := func(args map[string]any, k string) string { s, _ := args[k].(string); return s }
 	return []stdio.Tool{
 		{Name: check.TryTool,
-			Description: "Try a pushed head before its pull request is opened: the checker judges it as it judges a pull request's head, merged onto its trunk's head, " +
-				"its unit and integration levels through the build modules, and owes the forge nothing. Answers the try's id at once; " + check.TryReadTool + " reads " +
-				"where it stands. A try of the same head that waits or runs is the answer to a second ask; a new try is refused while 4 tries run on a build node or 8 wait for one, mesh-wide; tries let in while waiting may later all run at once, and each node's build capacity bounds what runs on it. A repository " +
-				"the checker checks no level of (one whose trunk the gate does not name) is refused. A try whose ask no build node took within the step " +
-				"bound ends as error; its ask stays in the build seat's stream and may still run later, judged by nobody (issue 734).",
-			Input: map[string]any{"type": "object", "required": []string{"repository", "head"}, "properties": map[string]any{
-				"repository": map[string]any{"type": "string", "description": "<owner>/<name>"},
-				"head":       map[string]any{"type": "string", "description": "the full commit to try, 40 or 64 hex digits"},
-				"trunk":      map[string]any{"type": "string", "description": "the trunk commit to merge it onto, or the trunk's branch for its head now; the trunk's head when absent"},
+			Description: "Try a delivery group, or one pushed head, before its pull requests are opened (try a group, group try, try several repositories): " +
+				"name the members, each a repository and the exact commit asked (never the branch's head now, so a push after the ask changes nothing of what is tried), " +
+				"or one repository and its head for a try of one member (the seat verb try of mesh-delivery-checker takes members from the registry milestone on; until it is delivered, ask a group through this tool). The checker judges it by the code a group's pull-request check runs, so the two cannot drift: " +
+				"each member merged onto its trunk's head, the unit and the integration level of every member through the build modules, the manifest validator over " +
+				"the members' manifests, the module graph, and the composition on every placed node. Every failure is named (each member, level, test, manifest and node), not " +
+				"the first. A try owes the forge nothing (no status, no Approve asked) and writes no verdict of a pull request; what its passing levels prove is kept, so a pull request's " +
+				"check of the same heads on the same trunk runs only what the try did not pass. A try narrowed to a level or to some tests judges only those, no manifest and no composition, and keeps nothing of tests. " +
+				"Answers the try's id at once; " + check.TryReadTool + " reads where it stands, " + check.TryEndTool + " ends it by hand. A try of the same commits that waits or runs is the answer to a second ask " +
+				"(whatever the order of the members); a new try is refused while 4 tries run on a build node or 8 wait for one, mesh-wide. A repository the checker checks no level of (one whose trunk the gate does not name) " +
+				"is refused. A try whose ask no build node took within the step bound ends as error; its ask stays in the build seat's stream and may still run later, judged by nobody (issue 734).",
+			Input: map[string]any{"type": "object", "properties": map[string]any{
+				"members": map[string]any{"type": "array", "description": "the group: one repository at most once, each at the exact commit asked and the trunk commit it is merged onto",
+					"items": map[string]any{"type": "object", "required": []string{"repository", "head"}, "properties": map[string]any{
+						"repository": map[string]any{"type": "string", "description": "<owner>/<name>"},
+						"head":       map[string]any{"type": "string", "description": "the full commit to try, 40 or 64 hex digits"},
+						"trunk":      map[string]any{"type": "string", "description": "the trunk commit to merge it onto, or the trunk's branch for its head now; the trunk's head when absent"}}}},
+				"repository": map[string]any{"type": "string", "description": "<owner>/<name>, for a try of one member (instead of members)"},
+				"head":       map[string]any{"type": "string", "description": "the full commit to try, 40 or 64 hex digits (with repository)"},
+				"trunk":      map[string]any{"type": "string", "description": "the trunk commit to merge it onto, or the trunk's branch for its head now; the trunk's head when absent (with repository)"},
 				"tests":      map[string]any{"type": "string", "description": "a go test -run pattern: only those tests run, and nothing is kept"},
 				"level":      map[string]any{"type": "string", "enum": []string{"unit", "integration"}, "description": "only this level; both when absent"}}},
 			Run: func(args map[string]any) (any, error) {
@@ -126,16 +136,32 @@ func TryTools(tr Trying) []stdio.Tool {
 				if tr.Now != nil {
 					now = tr.Now
 				}
+				var members []check.TryAskMember
+				if raw, ok := args["members"]; ok {
+					list, isList := raw.([]any)
+					if !isList {
+						return nil, fmt.Errorf("members is a list of {repository, head, trunk}")
+					}
+					for _, item := range list {
+						m, isMap := item.(map[string]any)
+						if !isMap {
+							return nil, fmt.Errorf("a member is {repository, head, trunk}")
+						}
+						members = append(members, check.TryAskMember{Repository: str(m, "repository"), Head: str(m, "head"), Trunk: str(m, "trunk")})
+					}
+				}
 				id, err := check.AskTry(tr.Tries, trunks, check.TryAsk{Repository: str(args, "repository"), Head: str(args, "head"),
-					Trunk: str(args, "trunk"), Tests: str(args, "tests"), Level: str(args, "level")}, now())
+					Trunk: str(args, "trunk"), Tests: str(args, "tests"), Level: str(args, "level"), Members: members}, now())
 				if err != nil {
 					return nil, err
 				}
 				return map[string]any{"id": id}, nil
 			}},
 		{Name: check.TryReadTool,
-			Description: "Where a try stands, as stored: queued, running, or its end (pass, fail, or error when it could not run), with what was said of it, " +
-				"the head and the trunk commit it was merged onto, the time it took and what failed first; while it runs, each ask it put as soon as it is put, " +
+			Description: "Where a try (of a group or of one head) stands, read whole, as stored: queued, running, or its end (pass, fail, or error when it could not run, or " +
+				"when its manifests and composition could not be judged), with what was said of it, every member's commit and the trunk commit it was merged onto, the time it took, " +
+				"every failure one line each (members, levels, tests, manifests, the composition per node), the levels' tests run and kept, the composition on every placed node, " +
+				"the notes of the check (manifests judged, module graph, kept verdicts); while it runs, each ask it put as soon as it is put, " +
 				"with the node that took it, its state and the phase its step says (fetch and merge, a level's digest, lint, tests) and since when. Read-only.",
 			Input: map[string]any{"type": "object", "required": []string{"id"}, "properties": map[string]any{
 				"id": map[string]any{"type": "string", "description": "the try's id, try-<digits>"}}},
@@ -146,7 +172,7 @@ func TryTools(tr Trying) []stdio.Tool {
 				return check.ReadTry(tr.Tries, str(args, "id"))
 			}},
 		{Name: check.TryEndTool,
-			Description: "End a try that waits or runs, as error, by hand: say why (kept in what it says). Its place among the 4 is free at once, " +
+			Description: "End a try of a group (or of one head) that waits or runs, as error, by hand: say why (kept in what it says). Its place among the 4 is free at once, " +
 				"the checker stops waiting for its asks, and the next " + check.TryTool + " of its head asks anew with a new id. For a try whose ask " +
 				"was lost (no step runs for it in checker_status); the checker ends one by itself when the build seat gives its ask up, or no node " +
 				"takes it within the step bound. A try that ended already is refused.",
@@ -170,6 +196,24 @@ func TryTools(tr Trying) []stdio.Tool {
 	}
 }

+// OpenTriesTools is the tool that lists the tries that wait or run, each with its members at their commits, and whether it is
+// a whole try (the indexer writes the candidate of a whole try's group): the read a part uses at its start to find the tries
+// whose start event it missed, instead of reading the checker's state.
+func OpenTriesTools(tr Trying) []stdio.Tool {
+	return []stdio.Tool{{Name: check.TriesTool,
+		Description: "The tries that wait or run now (a try of a group or of one head; try.started and try.ended on the checker's stream say the same), each with its id, state, its members at their exact commits and " +
+			"trunk commits, and whether it is a whole try (not narrowed to a level or to tests, so it is composed and its manifests judged). For a part that " +
+			"missed the checker's try.started or try.ended event (the indexer at its start); checker_try_read reads one try whole. Read-only.",
+		Input: map[string]any{"type": "object", "properties": map[string]any{}},
+		Run: func(map[string]any) (any, error) {
+			if tr.Tries == nil {
+				return nil, fmt.Errorf("the tries state cannot be read here")
+			}
+			open, err := check.OpenTries(tr.Tries)
+			return map[string]any{"tries": open}, err
+		}}}
+}
+
 // Seat is the seat the checker holds (novox/hq ADR 0547 §10, issue 774); its verbs are served as tools named <seat>.<verb>.
 const Seat = "mesh-delivery-checker"

@@ -325,7 +369,7 @@ func main() {
 		_, err := verdicts.Update(key, json.RawMessage(value), revision)
 		return err
 	}}
-	tools := append(append(append(Tools(r), TryTools(trying)...), SeatTryTools(trying)...), RecoveryTools(r, written)...)
+	tools := append(append(append(append(Tools(r), TryTools(trying)...), OpenTriesTools(trying)...), SeatTryTools(trying)...), RecoveryTools(r, written)...)
 	if err := stdio.Serve("", logged(tools)); err != nil {
 		fmt.Fprintf(os.Stderr, "[mesh-delivery-checker-tools] %v\n", err)
 		os.Exit(1)
@@ -8,6 +8,8 @@ import (
 	"testing"
 	"time"

+	"git.novox.be/novox/mesh-delivery/sdk/tryevent"
+
 	"mesh-delivery-checker/internal/check"
 )

@@ -106,6 +108,39 @@ func TestTheTryToolsAskAndReadATry(t *testing.T) { // ADR 0501 §5, the agreed i
 	if _, err := verbs[0].Run(map[string]any{"repository": "novox/hq", "head": strings.Repeat("1", 40)}); err == nil {
 		t.Error("the verb tried a repository nothing checks")
 	}
+	// A group try (issue 1921): the members, each an exact commit; members and one repository together are refused; the
+	// description says what it does in the words a search for "try a group" finds.
+	later := TryTools(Trying{Tries: store, Ender: store, Now: func() time.Time { return time.Unix(2, 5) },
+		Trunks: func() (map[string]string, error) {
+			return map[string]string{"novox/mesh-delivery": strings.Repeat("a", 40)}, nil
+		}})
+	g, err := later[0].Run(map[string]any{"members": []any{map[string]any{"repository": "novox/mesh-delivery", "head": strings.Repeat("2", 40)}}})
+	if err != nil || g.(map[string]any)["id"] == id {
+		t.Errorf("a group try = %v, %v, want a try of its own", g, err)
+	}
+	if _, err := tools[0].Run(map[string]any{"members": []any{map[string]any{"repository": "novox/mesh-delivery", "head": strings.Repeat("2", 40)}},
+		"repository": "novox/mesh-delivery", "head": strings.Repeat("1", 40)}); err == nil {
+		t.Error("members and a repository were both taken")
+	}
+	if _, err := tools[0].Run(map[string]any{"members": "novox/mesh-delivery"}); err == nil {
+		t.Error("members that are no list were taken")
+	}
+	for _, tl := range tools {
+		for _, words := range []string{"group"} {
+			if !strings.Contains(strings.ToLower(tl.Description), words) {
+				t.Errorf("%s says nothing of a %s: %q", tl.Name, words, tl.Description)
+			}
+		}
+	}
+	if d := strings.ToLower(tools[0].Description); !strings.Contains(d, "try a group") || !strings.Contains(d, "exact commit") || !strings.Contains(d, "every failure") ||
+		!strings.Contains(d, "composition on every placed node") || !strings.Contains(d, "owes the forge nothing") || !strings.Contains(d, "kept") {
+		t.Errorf("the try's description does not say what a group try does: %q", d)
+	}
+	if open := OpenTriesTools(Trying{Tries: store}); len(open) != 1 || open[0].Name != check.TriesTool || !strings.Contains(open[0].Description, "try.started") {
+		t.Errorf("open tries tool = %+v", open)
+	} else if out, err := open[0].Run(nil); err != nil || len(out.(map[string]any)["tries"].([]tryevent.Open)) != 2 {
+		t.Errorf("open tries = %v, %v, want the two tries asked", out, err)
+	}
 	// Issue 734: a try whose ask was lost is ended by hand with why, and its head is asked anew.
 	ended, err := tools[2].Run(map[string]any{"id": id, "why": "its ask was lost"})
 	if err != nil || ended.(map[string]any)["state"] != "error" {
@@ -862,9 +862,11 @@ func (s triesStore) Create(key string, value []byte) error {

 // TestATryIsJudgedAndItsEndWrittenWithNoStatusOwed: a try written as checker_try writes it is taken by the running checker,
 // judged through the build modules as a pull request's head merged onto its trunk, and ended pass in its key, with no
-// verdict and no status owed (ADR 0501 §5).
+// verdict and no status owed (ADR 0501 §5). A whole try waits for the indexer's candidate of its group, which it reads on the
+// key's watch, and writes the merge previews the indexer makes it from (issue 1921).
 func TestATryIsJudgedAndItsEndWrittenWithNoStatusOwed(t *testing.T) {
 	b := startBed(t)
+	asked := b.engine(t, "n1") // a whole try is composed on every placed node, as a group's check is
 	b.start(t, nil)
 	store := triesStore{b.buckets[check.TriesBucket], b.ctx}
 	id, err := check.AskTry(store, map[string]string{repo: trunk}, check.TryAsk{Repository: repo, Head: head1}, time.Now())
@@ -872,19 +874,36 @@ func TestATryIsJudgedAndItsEndWrittenWithNoStatusOwed(t *testing.T) {
 		t.Fatal(err)
 	}
 	var last check.Try
+	// The indexer's candidate of the try's group (here written by the test), at the heads of its members.
+	raw0, _ := store.Get(id)
+	first, _ := check.DecodeTry(raw0)
+	cand := delivery.Candidate{V: delivery.Version, Group: id, HeadsHash: check.TryCase(id, first, nil).HeadsHash,
+		Pulls: []delivery.CandidatePull{{Head: delivery.Head{Repository: repo, Head: head1}, Modules: []string{}}}}
+	cand.FPSet = delivery.FingerprintSet(cand.Pulls)
+	data, err := delivery.EncodeCandidate(cand)
+	if err != nil {
+		t.Fatal(err)
+	}
+	ckey, _ := delivery.CandidatesKey(id)
+	if _, err := b.buckets[delivery.CandidatesBucket].Create(b.ctx, ckey, data); err != nil {
+		t.Fatal(err)
+	}
 	for deadline := time.Now().Add(20 * time.Second); time.Now().Before(deadline); time.Sleep(50 * time.Millisecond) {
 		raw, _ := store.Get(id)
 		if last, err = check.DecodeTry(raw); err == nil && last.Over() {
 			break
 		}
 	}
-	if last.State != check.TryPass || last.Trunk != trunk || last.Took == "" {
-		t.Fatalf("try = %+v, want passed on the trunk", last)
+	if last.State != check.TryPass || last.Trunk != trunk || last.Took == "" || last.Composition == nil {
+		t.Fatalf("try = %+v, want passed on the trunk with its composition made", last)
+	}
+	if got := asked(); len(got) != 1 || !strings.HasPrefix(got[0].Candidate, id+".") {
+		t.Errorf("the placed node's engine was asked %+v, want the try's candidate %s.<heads>", got, id)
 	}
 	if b.fake.count("mesh-build-go.build_go_fetch") == 0 {
 		t.Errorf("the try fetched nothing")
 	}
-	for _, name := range []string{delivery.CheckerOwedBucket, delivery.CheckerVerdictsBucket, delivery.PreviewsBucket} {
+	for _, name := range []string{delivery.CheckerOwedBucket, delivery.CheckerVerdictsBucket} {
 		if keys, _ := b.buckets[name].Keys(b.ctx); len(keys) != 0 {
 			t.Errorf("a try wrote %s: %v", name, keys)
 		}
@@ -29,7 +29,10 @@ type judgeDeps struct {
 	trunks   *check.Trunks
 	kept     check.KV
 	previews check.KV
-	repos    *repoModules
+	// candidates answers the indexer's candidate of a try's group (try_candidates.go); nil leaves a whole try with no
+	// manifest or composition judged, said.
+	candidates check.TryCandidates
+	repos      *repoModules
 	// published is the indexer's packages state as it is followed (packages.go).
 	published *publishedPackages
 	forge     check.Forge
@@ -157,7 +160,7 @@ func newJudge(d judgeDeps) check.Judge {
 		nodes = d.nodes
 	}
 	ex := &check.Examiner{Nodes: nodes, Compositions: d.compositions, Asks: d.asks, Toolchains: d.tools,
-		Kept: check.Kept{Store: d.kept}, Previews: d.previews, Modules: d.repos, Packages: d.repos, Published: d.published, Forge: d.forge, Runs: d.repos, Builds: d.builds, BuildEnds: d.ends, BuildWait: d.buildWait, Announce: d.announce, Trunks: d.trunks, Manifests: d.repos, Read: d.repos, Predefined: d.predefined, Logf: d.logf}
+		Kept: check.Kept{Store: d.kept}, Previews: d.previews, Candidates: d.candidates, Modules: d.repos, Packages: d.repos, Published: d.published, Forge: d.forge, Runs: d.repos, Builds: d.builds, BuildEnds: d.ends, BuildWait: d.buildWait, Announce: d.announce, Trunks: d.trunks, Manifests: d.repos, Read: d.repos, Predefined: d.predefined, Logf: d.logf}
 	if d.nodes != nil && d.builds != nil && d.repos != nil {
 		ex.Serving = runningServes{have: d.nodes, builds: d.builds, read: d.repos, logf: d.logf}
 	}
@@ -21,6 +21,7 @@ import (
 	"github.com/nats-io/nats.go/jetstream"

 	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-builder/buildrun"
+	"git.novox.be/novox/mesh-delivery/sdk/tryevent"
 	"git.novox.be/novox/mesh-sdk/go/announce"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 	"git.novox.be/novox/mesh-sdk/go/process"
@@ -189,7 +190,13 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 		Verdicts: verdicts.all,
 	}
 	// The tries (ADR 0501 §5) are judged by the same judge, held by the same deliveries.
-	tryer := &check.Tryer{Tries: kvStore{buckets[check.TriesBucket]}, Bound: checkBound, NotTaken: stepBound, Logf: logger.Printf}
+	tryer := &check.Tryer{Tries: kvStore{buckets[check.TriesBucket]}, Bound: checkBound, NotTaken: stepBound, Logf: logger.Printf,
+		// A whole try's start and end are said on the stream checks, for the indexer to write and delete the candidate of its group.
+		Say: func(ctx context.Context, event string, body tryevent.Event) error {
+			data, _ := json.Marshal(body)
+			_, err := js.Publish(ctx, eventSubject(event), data, jetstream.WithRetryAttempts(10), jetstream.WithRetryWait(time.Second))
+			return err
+		}}
 	announce := func(ctx context.Context, event, key string) {
 		body, _ := json.Marshal(map[string]string{"key": key})
 		if _, err := js.Publish(ctx, eventSubject(event), body); err != nil {
@@ -216,7 +223,7 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 	ch.Runs = repos // the node-engine a check reads beside at its running commit (ADR 0548 §6)
 	ch.Judge = newJudge(judgeDeps{
 		asks: buildrun.Asker{Publisher: asks, Waiter: waiter, Bound: stepBound}, tools: tools, trunks: trunks,
-		kept: kvStore{buckets[delivery.CheckerKeptBucket]}, previews: kvStore{buckets[delivery.PreviewsBucket]},
+		kept: kvStore{buckets[delivery.CheckerKeptBucket]}, previews: kvStore{buckets[delivery.PreviewsBucket]}, candidates: tryCandidates{buckets[delivery.CandidatesBucket]},
 		repos: repos, published: published, builds: builds, ends: ends, buildWait: set.buildWait, forge: forgeReads{call: caller.Call}, logf: logger.Printf,
 		announce: announce, compositions: compositions,
 		nodes: openNodeNames(ctx, js, logger.Printf),
@@ -333,6 +340,9 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 		})
 	}()
 	each := func(e jetstream.KeyValueEntry) {
+		if check.IsTryGroup(e.Key()) {
+			return // a group try's candidate: its try judges it, and the forge is owed nothing (issue 1921)
+		}
 		if opOf(e) {
 			ch.Candidate(ctx, e.Key(), e.Value())
 		} else {
@@ -0,0 +1,72 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/nats-io/nats.go/jetstream"
+
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+)
+
+// candidateWaitsOnPreview is the None2 of a module the indexer wrote from a pull message alone, before it had the merge
+// preview of the head (the indexer's NoneNoPreview): its fingerprint comes with the preview, so a candidate that still says
+// it is not yet the candidate of the heads previewed. It moves to mesh-sdk's delivery package with the next change there.
+const candidateWaitsOnPreview = "no merge preview is computed"
+
+// tryCandidates answers the indexer's candidate of a try's group (novox/hq ADR 0593 §7, issue 1921): the candidate the
+// engines compose and the manifest validator judges, which the indexer makes of the try's previews. It waits for it on the
+// key's own watch, with no timer between reads, and gives up at the bound.
+type tryCandidates struct{ kv jetstream.KeyValue }
+
+func (t tryCandidates) TryCandidate(ctx context.Context, group, heads string, bound time.Duration) (delivery.Candidate, error) {
+	key, err := delivery.CandidatesKey(group)
+	if err != nil {
+		return delivery.Candidate{}, err
+	}
+	if bound <= 0 {
+		bound = time.Minute
+	}
+	waiting, cancel := context.WithTimeout(ctx, bound)
+	defer cancel()
+	w, err := t.kv.Watch(waiting, key) // the value now, then each change
+	if err != nil {
+		return delivery.Candidate{}, fmt.Errorf("the indexer's candidate %s cannot be watched: %w", key, err)
+	}
+	defer func() { _ = w.Stop() }()
+	last := "the indexer holds none"
+	for {
+		select {
+		case <-waiting.Done():
+			return delivery.Candidate{}, fmt.Errorf("the indexer wrote no candidate of %s at heads %s within %s (%s)", group, heads, bound, last)
+		case e := <-w.Updates():
+			if e == nil || e.Operation() != jetstream.KeyValuePut {
+				continue
+			}
+			c, err := delivery.DecodeCandidate(e.Value())
+			switch {
+			case err != nil:
+				last = "what it holds is not a candidate: " + err.Error()
+			case c.HeadsHash != heads:
+				last = "it holds heads " + c.HeadsHash
+			case waitsOnPreview(c):
+				last = "it has not yet the merge previews' fingerprints"
+			default:
+				return c, nil
+			}
+		}
+	}
+}
+
+// waitsOnPreview says a module of the candidate has no fingerprint yet because its preview was not read.
+func waitsOnPreview(c delivery.Candidate) bool {
+	for _, p := range c.Pulls {
+		for _, m := range p.Fps {
+			if m.None2 == candidateWaitsOnPreview {
+				return true
+			}
+		}
+	}
+	return false
+}
@@ -3,7 +3,7 @@ module mesh-delivery-checker
 go 1.26.0

 require (
-	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261103221822-85ba0a9a70d8
+	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261104002338-5a38a1221659
 	github.com/nats-io/nats-server/v2 v2.11.17
 	github.com/nats-io/nats.go v1.54.0
 )
@@ -1,7 +1,7 @@
 git.novox.be/novox/mesh-catalog/modules/mesh-build-go/buildstep v0.0.0-20261102193506-d221c633799a h1:oxgksCiq272/afXbUION/dxtAS5MPGnmyq6+AZQxmXg=
 git.novox.be/novox/mesh-catalog/modules/mesh-build-go/buildstep v0.0.0-20261102193506-d221c633799a/go.mod h1:kpsX4Pgss5EeuBvel1zWa2ogj7MkR3jZso6oa/J0YUQ=
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261103221822-85ba0a9a70d8 h1:XEbIVImp6yGjA91rp0iZBoDdL5KfamjOuDLwWvqh0hc=
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261103221822-85ba0a9a70d8/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261104002338-5a38a1221659 h1:tK7MzxVm/ECNg1Yblhh1ynVEthbZCg2mSPW0wQZC0b0=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261104002338-5a38a1221659/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op h1:Z/MZK75wC/NSrkgqeNIa7jexam9uWzhLmFTSCPI/kn0=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op/go.mod h1:FQyySiasQQM8735Ddel3MRojmy4dA1IqCeyJ5jmPMbI=
 github.com/google/go-tpm v0.9.8 h1:slArAR9Ft+1ybZu0lBwpSmpwhRXaa85hWtMinMyRAWo=
@@ -29,18 +29,23 @@ const (
 	nodeEngineModule    = "mesh-host"
 	// networkingRepository holds route-proxy, whose manifest the node-engine's proofs of a composition read.
 	networkingRepository = "novox/mesh-networking"
+	// contractsRepository and deliveryRepository hold the seat definitions mesh-sdk's bootstrapped seats are compared with: its
+	// tests read both beside it (beside.Dir "mesh-contracts" and "mesh-delivery"), at the group's head for a member, else at the
+	// trunk (a group try lays them out the same way: besideFor serves the check and the try).
+	contractsRepository = "novox/mesh-contracts"
+	deliveryRepository  = DeliveryRepository
 )

 // besideRules are the repositories each core repository's tests read, as the tests state it (mesh-sdk go/internal/beside
 // beside.go): the catalogue, the node-engine, the SDK, and the delivery's pinned forge dependencies (mesh-catalog
 // checks/deps). Which commit of each is besideCommit's rule. No repository's tests read the controller, which ended by its
 // unassignment (novox/hq ADR 0590, issue 1126), and its repository is emptied and archived (ADR 0593 §11), so it has no
-// siblings placed either. The catalogue's tests read the node-engine since its composer command moved there (ADR 0593
+// siblings placed either. mesh-sdk reads mesh-contracts and mesh-delivery (its bootstrapped seats against their contracts files). The catalogue's tests read the node-engine since its composer command moved there (ADR 0593
 // §7): mesh-build-go builds it for a compose ask. The node-engine's read mesh-networking since route-proxy's proofs of a
 // composition moved into them (ADR 0593).
 var besideRules = map[string][]string{
 	nodeEngineRepo:        {catalogueRepository, SDKRepository, networkingRepository},
-	SDKRepository:         {catalogueRepository, nodeEngineRepo},
+	SDKRepository:         {catalogueRepository, nodeEngineRepo, contractsRepository, deliveryRepository},
 	catalogueRepository:   {SDKRepository, nodeEngineRepo},
 	"novox/mesh-delivery": {SDKRepository, catalogueRepository},
 }
@@ -55,6 +55,8 @@ type Case struct {
 	Watch func(askID string, step *delivery.Step)
 	// Progress says what the check is doing, so a check that ran past its bound names the step it was stuck at.
 	Progress *Progress
+	// Wait says what a whole try waits for now ("" when nothing); the try keeps it for try-read. Nil for a pull request's check.
+	Wait func(why string)
 	// Kind is what asked the check (KindNew, KindNodes, KindTrunk): a carry after a trunk or sibling move is asked on the
 	// build seats' recheck stream, every other check on check (ADR 0536 §4, ADR 0548 §5).
 	Kind string
@@ -1035,8 +1035,25 @@ func TestTheIndexersJudgeJudgesTheChangesManifests(t *testing.T) {
 		// mail's tool while mail awaits web's database: both left out, so neither is refused (ADR 0614 §3, §6).
 		cycle      string
 		trunkCycle bool
+		// indexer makes web the holder of the seat mesh-catalog, and the trunk's manifest validator answers for it: "held" with no verdict,
+		// "aside" with a field it does not know; ownJudge has the group change the judge, so the manifest is also judged by the
+		// trunk's, in a second ask (ADR 0633 clause 6, 1585/T22, T23)
+		indexer  string
+		ownJudge bool
+		// try judges the same change as a whole group try, whose manifests come from the indexer's candidate of the try's
+		// group (issue 1921): the same judge, the same verdicts.
+		try bool
 	}{
 		{name: "accepted"},
+		{name: "accepted in a group try", try: true},
+		{name: "refused in a group try", try: true, refused: "web has no id", fails: "the indexer's judge at mesh-delivery's trunk " + strings.Repeat("d", 40) + ` refuses the manifest of web: web has no id`},
+		{name: "a cycle the group try makes", try: true, cycle: "provisions", fails: "the change's module graph has the cycle mail -> web -> mail"},
+		{name: "the indexer accepted by the trunk's manifest validator", indexer: "ok"},
+		{name: "the indexer held by the trunk's manifest validator", indexer: "held", fails: "the indexer web, the holder of the seat mesh-catalog, would never run: the trunk's manifest validator at mesh-delivery's trunk " + strings.Repeat("d", 40) + " does not accept its manifest: the manifest validator holds it, with no verdict yet"},
+		{name: "the indexer with a field the trunk's manifest validator does not know", indexer: "aside", fails: "the manifest validator does not know its fields new_field, so it waits"},
+		{name: "the indexer refused by the trunk's manifest validator", indexer: "refused", refused: "web has no id", fails: "does not accept its manifest: web has no id"},
+		{name: "the indexer under a changed judge is judged by the trunk's as well", indexer: "aside", ownJudge: true, fails: "the manifest validator does not know its fields new_field, so it waits"},
+		{name: "a touched manifest the judge holds", indexer: "heldplain", fails: "holds the manifest of web: it gave no verdict"},
 		{name: "an untouched manifest's problem the trunk had", untouched: "mail says no credential form", trunkMail: "mail says no credential form"},
 		{name: "a problem the change causes in an untouched manifest", untouched: "mail reads a state web no longer keeps",
 			fails: "refuses the manifest of mail: mail reads a state web no longer keeps"},
@@ -1077,6 +1094,10 @@ func TestTheIndexersJudgeJudgesTheChangesManifests(t *testing.T) {
 			}
 			b.ex.Read = fixedManifests{strings.Repeat("a", 64): mail, strings.Repeat("b", 64): trunkWeb, web: changed}
 		}
+		if row.indexer != "" && row.indexer != "heldplain" {
+			b.ex.Read = fixedManifests{strings.Repeat("a", 64): {Module: "mail"}, strings.Repeat("b", 64): {Module: "web"},
+				web: {Module: "web", Claims: []catalogue.Claim{{Name: CatalogSeat}}}}
+		}
 		var judged []delivery.ComposeJob
 		answer := b.asks.Answer
 		b.asks.Answer = func(a delivery.StepAsk) delivery.Step {
@@ -1085,6 +1106,12 @@ func TestTheIndexersJudgeJudgesTheChangesManifests(t *testing.T) {
 			}
 			judged = append(judged, *a.Compose)
 			read := composer.ManifestRead{Accepted: row.refused == "", Refused: row.refused}
+			switch row.indexer {
+			case "held", "heldplain":
+				read = composer.ManifestRead{}
+			case "aside":
+				read.SetAside = "new_field"
+			}
 			verdict, _ := json.Marshal(composer.Verdict{V: composer.Version, SDK: "exe:1", Cases: []composer.CaseVerdict{{Name: JudgeCase,
 				Manifests: map[string]composer.ManifestRead{"web": read, "mail": {Accepted: row.untouched == "", Refused: row.untouched}}},
 				{Name: JudgeTrunk, Manifests: map[string]composer.ManifestRead{"web": {Accepted: true}, "mail": {Accepted: row.trunkMail == "", Refused: row.trunkMail}}}}})
@@ -1092,9 +1119,29 @@ func TestTheIndexersJudgeJudgesTheChangesManifests(t *testing.T) {
 			return delivery.Step{ID: a.ID, State: delivery.StepPassed, Result: result}
 		}
 		p := pullOf(repoA, 7, head1)
+		if row.ownJudge {
+			p = pullOf(DeliveryRepository, 7, head1)
+			b.fetch.Changed = []string{JudgeDir + "/judge/judge.go"}
+		}
 		p.Modules = []string{"web"}
 		p.Fps = map[string]delivery.CandidateModule{"web": {FP2: "src2:" + strings.Repeat("f", 64), Manifest: web}}
-		v := b.judge(t, caseOf(t, p)).Verdict
+		cs := caseOf(t, p)
+		if row.try {
+			cs = TryCase("try-1", Try{Members: []TryMember{{Repository: repoA, Head: head1, Trunk: trunkA}}}, nil)
+			b.ex.Candidates = &fakeTryCandidates{cand: delivery.Candidate{FPSet: "fps", Pulls: []delivery.CandidatePull{p}}}
+		}
+		v := b.judge(t, cs).Verdict
+		if row.indexer == "ok" && !slices.ContainsFunc(cs.notes, func(n string) bool {
+			return strings.Contains(n, "the new indexer's manifest of web is accepted by the trunk's manifest validator")
+		}) {
+			t.Errorf("%s: the case says %v, want the new indexer's manifest said accepted by the trunk's manifest validator", row.name, cs.notes)
+		}
+		if row.ownJudge && (len(judged) != 2 || judged[0].Fetch["commit"] != head1 || judged[1].Fetch["commit"] != trunk) {
+			t.Fatalf("%s: judged %+v, want the head's judge and then the trunk's", row.name, judged)
+		}
+		if row.ownJudge {
+			judged = judged[1:]
+		}
 		if len(judged) != 1 || judged[0].Fetch["repository"] != DeliveryRepository || judged[0].Fetch["commit"] != trunk ||
 			judged[0].Package != JudgePackage || judged[0].Dir != JudgeDir {
 			t.Fatalf("%s: judged %+v (verdict %+v)", row.name, judged, v)
@@ -30,7 +30,7 @@ type ManifestReader interface {
 // refuseCycle fails the check for a cycle of the change's module graph, naming it; nil when the case touches no manifest,
 // when nothing reads manifests, or when there is none. A manifest that cannot be read fails the check, said, never passes it.
 func (st *state) refuseCycle(ctx context.Context) *delivery.Verdict {
-	if st.j.Manifests == nil || st.j.Read == nil || st.c.Try != nil {
+	if st.j.Manifests == nil || st.j.Read == nil || st.narrowTry() {
 		return nil
 	}
 	trunk := st.j.Manifests.ManifestDigests()
@@ -139,8 +139,18 @@ type Examiner struct {
 	Nodes interface {
 		Names(ctx context.Context) ([]string, error)
 	}
-	Now  func() time.Time
-	Logf func(format string, args ...any)
+	// Candidates answers the indexer's candidate of a try's group once it wrote it from the try's previews, the manifests
+	// and fingerprints a group try's manifest validator and composition judge (issue 1921); nil leaves a whole try with no
+	// manifest or composition judged, said.
+	Candidates TryCandidates
+	Now        func() time.Time
+	Logf       func(format string, args ...any)
+}
+
+// TryCandidates answers the candidate the indexer holds for a try's group at its heads hash, waiting for it within the
+// bound; an error says it did not come (and why).
+type TryCandidates interface {
+	TryCandidate(ctx context.Context, group, heads string, bound time.Duration) (delivery.Candidate, error)
 }

 // CompositionReader makes a check's composition verdict; an error is only a case that cannot be composed at all.
@@ -246,6 +256,50 @@ type state struct {
 	// unpreviewed are the members (pullKey) with no preview of a merge: a head that does not merge, or a fetch that did not
 	// answer. The indexer holds no manifest of them, so the assigner's composition would only wait: it is not awaited.
 	unpreviewed []string
+	// noCandidate says why a whole try has no candidate of its group from the indexer, so its manifests were not judged and
+	// it was not composed; empty when it has one, and for a pull request's check.
+	noCandidate string
+}
+
+// narrowTry says the case is a try narrowed to a level or to some tests: it judges no manifest, graph or composition.
+func (st *state) narrowTry() bool { return st.c.Try != nil && !st.c.Try.Whole() }
+
+// takeTryCandidate gives a whole try's pulls the fingerprints and manifests the indexer's candidate of its group holds
+// (the group's pull-request check has them from its candidate, CaseOf), once the indexer wrote it from the try's previews.
+// A try with no such candidate is said so, in a note and in its composition, and is no pass (Tryer.run).
+func (st *state) takeTryCandidate(ctx context.Context) {
+	if st.c.Try == nil || !st.c.Try.Whole() {
+		return
+	}
+	no := func(why string) {
+		st.noCandidate = "the group's manifests and composition were not judged: " + why
+		st.c.note(st.noCandidate)
+	}
+	if st.j.Candidates == nil {
+		no("the checker reads no candidate of the indexer's")
+		return
+	}
+	if len(st.unpreviewed) > 0 {
+		no("no preview of a merge of " + strings.Join(st.unpreviewed, ", ") + " (its head does not merge or its fetch did not answer)")
+		return
+	}
+	if st.c.Wait != nil {
+		st.c.Wait("the indexer's candidate of the group at its heads (up to " + st.j.buildWait().String() + ")")
+		defer st.c.Wait("")
+	}
+	cand, err := st.j.Candidates.TryCandidate(ctx, st.c.Group, st.c.HeadsHash, st.j.buildWait())
+	if err != nil {
+		no(err.Error())
+		return
+	}
+	for i, p := range st.c.Pulls {
+		for _, cp := range cand.Pulls {
+			if cp.Repository == p.Repository && cp.Head.Head == p.Head {
+				st.c.Pulls[i].Modules, st.c.Pulls[i].Fps = cp.Modules, cp.Fps
+			}
+		}
+	}
+	st.c.FPSet = cand.FPSet
 }

 // Judge runs the case (it is the Judge of a Checker). A failure of the change, of a merge or of a step is a verdict; an error is only a case that cannot
@@ -256,6 +310,7 @@ func (j *Examiner) Judge(ctx context.Context, c *Case) (Outcome, error) {
 	// Every member and level runs to its end, and every manifest the change touches is judged by the indexer's judge (ADR
 	// 0578 §2), also after a failure: the verdict names every failure, not only the first (the operator, 2026-11-02).
 	tests := st.judgeAll(ctx)
+	st.takeTryCandidate(ctx)
 	if v := settled(joinFailures(tests, st.judgeManifests(ctx), st.refuseCycle(ctx))); v != nil {
 		return st.finish(ctx, *v), nil
 	}
@@ -282,7 +337,14 @@ func (st *state) composed(ctx context.Context, v *delivery.Verdict) {
 		st.c.note("the composition is kept: no fingerprint of a module it composed changed")
 		return
 	}
-	if st.j.Compositions == nil || st.c.Try != nil {
+	if st.narrowTry() {
+		return
+	}
+	if st.noCandidate != "" {
+		v.Composition = &delivery.Composition{State: delivery.CompositionNotRun, Words: st.noCandidate}
+		return
+	}
+	if st.j.Compositions == nil {
 		return
 	}
 	if len(st.unpreviewed) > 0 {
@@ -433,7 +495,7 @@ func (st *state) judgeAll(ctx context.Context) *delivery.Verdict {
 		// Every build module's fetch merged (each is in merged once): the preview is written, also when the member's tests
 		// failed, so the indexer holds its manifests and the assigner can compose the change (review of 650a1d0).
 		switch {
-		case st.c.Try != nil: // a try owes the indexer no preview: no pull request holds its head
+		case st.narrowTry(): // a try of a level or some tests owes the indexer no preview: it judges no manifest
 		case len(merged) == len(modules):
 			st.j.writePreview(ctx, p, merged)
 		default:
@@ -562,7 +624,7 @@ func (st *state) askNeeding(ctx context.Context, t *target, merged *[]Fetched, l
 		return fail(step.Node, fmt.Sprintf("the fetch of %s#%d answered no workspace: %s", p.Repository, p.Number, answer.Fetch))
 	}
 	if len(t.fetched.Conflicts) > 0 {
-		if st.c.Try == nil {
+		if !st.narrowTry() {
 			st.j.writePreview(ctx, p, append(*merged, t.fetched))
 		}
 		return fail(step.Node, fmt.Sprintf("%s#%d %s%s", p.Repository, p.Number, ConflictWords, strings.Join(t.fetched.Conflicts, ", ")))
@@ -97,7 +97,7 @@ func judgeRequest(trunk map[string]string, pulls []Pull) (req composer.Request,
 // refuses. A case that touches no manifest, or an examiner that reads no trunk manifests, judges nothing; a judge that
 // cannot be asked or does not answer fails the check, said, never passes it.
 func (st *state) judgeManifests(ctx context.Context) *delivery.Verdict {
-	if st.j.Manifests == nil || st.c.Try != nil {
+	if st.j.Manifests == nil || st.narrowTry() {
 		return nil
 	}
 	req, touched := judgeRequest(st.j.Manifests.ManifestDigests(), st.c.Pulls)
@@ -120,26 +120,12 @@ func (st *state) judgeManifests(ctx context.Context) *delivery.Verdict {
 		req.Predefined = list
 		st.c.note("the manifests are judged against the predefined keys of " + from)
 	}
-	raw, err := json.Marshal(req)
-	if err != nil {
-		return fail(goModule, err.Error())
+	cv, trunkCase, v := st.runJudge(ctx, req, touched, commit, at)
+	if v != nil {
+		return v
 	}
-	job := delivery.ComposeJob{Fetch: map[string]any{"repository": DeliveryRepository, "commit": commit}, Dir: JudgeDir,
-		Package: JudgePackage, Request: raw, Reader: "the indexer's judge at " + at}
-	a := delivery.StepAsk{ID: buildstep.NewID(), Kind: delivery.AskCheck, Language: delivery.AskGo, Asker: delivery.CheckerModule,
-		At: st.j.now().UTC(), Compose: &job}
-	st.c.Progress.Set(fmt.Sprintf("the judge ask %s of the manifests of %s", a.ID, strings.Join(touched, ", ")), "")
-	st.c.Asked(a.ID)
-	if err := st.j.Asks.Put(ctx, a); err != nil {
-		return fail(goModule, "the judge of the change's manifests could not be asked: "+err.Error())
-	}
-	step, err := st.j.Asks.Wait(ctx, a)
-	if err != nil {
-		return fail(goModule, "the judge of the change's manifests: "+err.Error())
-	}
-	cv, trunkCase, why := judgeAnswer(step)
-	if why != "" {
-		return fail(goModule, fmt.Sprintf("the indexer's judge at %s did not judge the change's manifests: %s", at, why))
+	if v := st.refuseUnmovableIndexer(ctx, req, touched, cv, at); v != nil {
+		return v
 	}
 	// A new or changed manifest is judged in full; of one the change leaves as it is, a problem the trunk already had is a
 	// warning (it is not refused for a rule it already broke), and a problem the change causes in it, which the trunk case
@@ -147,7 +133,13 @@ func (st *state) judgeManifests(ctx context.Context) *delivery.Verdict {
 	var refused, warned []string
 	for _, module := range slices.Sorted(maps.Keys(cv.Manifests)) {
 		r := cv.Manifests[module]
-		if r.Accepted || r.Refused == "" {
+		if r.Accepted {
+			continue
+		}
+		if r.Refused == "" { // held: a verdict not given is not one given (ADR 0633 clause 6)
+			if slices.Contains(touched, module) {
+				refused = append(refused, fmt.Sprintf("the indexer's judge at %s holds the manifest of %s: it gave no verdict", at, module))
+			}
 			continue
 		}
 		had := map[string]bool{}
@@ -183,6 +175,97 @@ func (st *state) judgeManifests(ctx context.Context) *delivery.Verdict {
 	return nil
 }

+// runJudge asks the Go build seat to build the judge at the commit and run it over the request, and reads its change and
+// trunk cases; a failed verdict when it cannot be asked or does not answer.
+func (st *state) runJudge(ctx context.Context, req composer.Request, touched []string, commit, at string) (change, trunk composer.CaseVerdict, v *delivery.Verdict) {
+	raw, err := json.Marshal(req)
+	if err != nil {
+		return change, trunk, fail(goModule, err.Error())
+	}
+	job := delivery.ComposeJob{Fetch: map[string]any{"repository": DeliveryRepository, "commit": commit}, Dir: JudgeDir,
+		Package: JudgePackage, Request: raw, Reader: "the indexer's judge at " + at}
+	a := delivery.StepAsk{ID: buildstep.NewID(), Kind: delivery.AskCheck, Language: delivery.AskGo, Asker: delivery.CheckerModule,
+		At: st.j.now().UTC(), Compose: &job}
+	st.c.Progress.Set(fmt.Sprintf("the judge ask %s of the manifests of %s", a.ID, strings.Join(touched, ", ")), "")
+	st.c.Asked(a.ID)
+	if err := st.j.Asks.Put(ctx, a); err != nil {
+		return change, trunk, fail(goModule, "the judge of the change's manifests could not be asked: "+err.Error())
+	}
+	step, err := st.j.Asks.Wait(ctx, a)
+	if err != nil {
+		return change, trunk, fail(goModule, "the judge of the change's manifests: "+err.Error())
+	}
+	change, trunk, why := judgeAnswer(step)
+	if why != "" {
+		return change, trunk, fail(goModule, fmt.Sprintf("the indexer's judge at %s did not judge the change's manifests: %s", at, why))
+	}
+	return change, trunk, nil
+}
+
+// CatalogSeat is the seat the indexer holds: the module whose manifest claims it is the indexer, found by the claim and
+// never by its name (novox/hq ADR 0633 clause 6, ADR 0601 §4).
+const CatalogSeat = "mesh-catalog"
+
+// refuseUnmovableIndexer fails the check when the trunk's manifest validator, the one the running parts hold, would
+// refuse or hold the change's new indexer manifest: such an indexer would never run, and every revision behind it would
+// wait for ever (ADR 0633 clause 6). The indexer is the touched module whose manifest claims the seat mesh-catalog.
+// When the change judges with its own head's manifest validator (it changes it), the manifest is judged by the trunk's
+// as well. The verdicts read are the trunk's manifest validator's: its change case, where refused, held (not accepted
+// with no reason) or with a field set aside (a field the running manifest validator does not know waits, ADR 0601 §3)
+// each fail it, naming the module and the problems.
+func (st *state) refuseUnmovableIndexer(ctx context.Context, req composer.Request, touched []string, cv composer.CaseVerdict, judgedAt string) *delivery.Verdict {
+	if st.j.Read == nil {
+		return nil
+	}
+	var indexer string
+	for _, module := range touched {
+		m, err := st.j.Read.Manifest(ctx, req.Cases[0].Manifests[module].Digest)
+		if err != nil {
+			return fail(goModule, fmt.Sprintf("the manifest of %s cannot be read, so the indexer cannot be ruled out: %v", module, err))
+		}
+		for _, c := range m.Claims {
+			if c.Name == CatalogSeat {
+				indexer = module
+			}
+		}
+	}
+	if indexer == "" {
+		return nil
+	}
+	if st.judgeHead != "" {
+		trunk := ""
+		if st.j.Trunks != nil {
+			trunk = st.j.Trunks.Heads()[DeliveryRepository]
+		}
+		if trunk == "" {
+			return fail(goModule, "the new indexer cannot be judged by the trunk's manifest validator: the trunk head of "+DeliveryRepository+" is not known")
+		}
+		var v *delivery.Verdict
+		judgedAt = "mesh-delivery's trunk " + trunk
+		if cv, _, v = st.runJudge(ctx, req, touched, trunk, judgedAt); v != nil {
+			return v
+		}
+	}
+	r, ok := cv.Manifests[indexer]
+	var problems []string
+	switch {
+	case !ok:
+		problems = append(problems, "the manifest validator gave no verdict")
+	case r.Refused != "":
+		problems = append(problems, strings.Split(r.Refused, "\n")...)
+	case !r.Accepted:
+		problems = append(problems, "the manifest validator holds it, with no verdict yet")
+	case r.SetAside != "":
+		problems = append(problems, "the manifest validator does not know its fields "+r.SetAside+", so it waits")
+	}
+	if len(problems) > 0 {
+		return fail(goModule, fmt.Sprintf("the indexer %s, the holder of the seat %s, would never run: the trunk's manifest validator at %s does not accept its manifest: %s",
+			indexer, CatalogSeat, judgedAt, strings.Join(problems, "; ")))
+	}
+	st.c.note(fmt.Sprintf("the new indexer's manifest of %s is accepted by the trunk's manifest validator at %s", indexer, judgedAt))
+	return nil
+}
+
 // judgeAnswer reads the judge's change and trunk cases from its step, or why it cannot.
 func judgeAnswer(step delivery.Step) (change, trunk composer.CaseVerdict, why string) {
 	if step.State != delivery.StepPassed {
@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"maps"
+	"strings"

 	"git.novox.be/novox/mesh-sdk/go/delivery"
 )
@@ -58,6 +59,28 @@ func (st *state) packagesOf(repository string) delivery.PackageVersions {
 			delete(versions, pkg)
 		}
 	}
+	// A package of a member that no indexer state publishes yet (a repository whose packages are all new) is in no list above,
+	// and the build would look for it as the trunk's latest version, which does not exist (issue 1921). The member's root
+	// module path stands for its repository: the build module takes the head of a repository from any package of it.
+	for _, m := range st.c.Pulls {
+		if delivery.SameRepository(m.Repository, repository) || len(m.Head) != 40 {
+			continue
+		}
+		name := strings.TrimPrefix(m.Repository, "novox/")
+		if m.Repository == name {
+			continue
+		}
+		held := false
+		for pkg := range versions {
+			if repo, _, ok := delivery.PackageRepository(pkg); ok && repo == m.Repository {
+				held = true
+				break
+			}
+		}
+		if !held {
+			versions[delivery.ForgeModulePrefix+name] = m.Head
+		}
+	}
 	if len(versions) == 0 {
 		return nil
 	}
@@ -60,6 +60,15 @@ func TestAGroupMemberIsBuiltAgainstTheSDKMembersHeadWhateverItsGoModNames(t *tes
 	if got := packagesOfFetch(t, b, "novox/mesh-catalog"); len(got) != 2 || got[SDKModulePath] != trunkS || got[contract] != trunkA {
 		t.Errorf("a pull request alone is built against %v, want every package at its latest published version", got)
 	}
+	// A member that publishes no package yet is still named, by its root module path, at its head (issue 1921).
+	b = newBench(t)
+	b.ex.Published = published{}
+	if v := b.judge(t, caseOf(t, pullOf(repoA, 7, head1), pullOf("novox/mesh-host", 8, head2))).Verdict; v.State != delivery.VerdictPass {
+		t.Fatalf("an unpublished member: verdict = %+v", v)
+	}
+	if got := packagesOfFetch(t, b, repoA); len(got) != 1 || got["git.novox.be/novox/mesh-host"] != head2 {
+		t.Errorf("the member's packages = %v, want the unpublished member's root at its head %s alone", got, head2)
+	}
 }

 type runsAt map[string]string
@@ -111,10 +120,16 @@ func TestTheSiblingsAreWhereTheTestsStateThem(t *testing.T) { // review D2, ADR
 	}
 	// Alone, mesh-sdk's tests read the catalogue's trunk, and the verdict names it.
 	b = newBench(t)
-	b.ex.Trunks = trunksOf(t, map[string]string{SDKRepository: trunkS, catalogue: trunkA, host: trunkA2})
+	const contracts = "novox/mesh-contracts"
+	b.ex.Trunks = trunksOf(t, map[string]string{SDKRepository: trunkS, catalogue: trunkA, host: trunkA2, contracts: trunkA, DeliveryRepository: trunkA2})
 	if out := b.judge(t, caseOf(t, pullOf(SDKRepository, 7, head1))); out.Beside[catalogue] != trunkA {
 		t.Errorf("the siblings named for the verdict alone = %v, want the catalogue at its trunk %s", out.Beside, trunkA)
 	}
+	// mesh-sdk's tests compare its bootstrapped seats with their contracts files, read beside it: mesh-contracts and
+	// mesh-delivery, at their trunks alone (a group try is placed by the same besideFor, so it lays them out the same way).
+	if got := besideOf(t, b, SDKRepository); got[contracts].Commit != trunkA || got[DeliveryRepository].Commit != trunkA2 {
+		t.Errorf("beside mesh-sdk alone = %+v, want mesh-contracts at %s and mesh-delivery at %s", got, trunkA, trunkA2)
+	}
 	if c := besideOf(t, b, SDKRepository)[catalogue]; c.Commit != trunkA || c.Ref != "" {
 		t.Errorf("the catalogue beside mesh-sdk alone = %+v, want its trunk %s", c, trunkA)
 	}
@@ -164,6 +164,7 @@ func (r Reader) Pull(repository string, number int) (VerdictRead, error) {
 	if err != nil {
 		return VerdictRead{}, err
 	}
+	keys = slices.DeleteFunc(keys, IsTryGroup)
 	sort.Strings(keys)
 	keys, cut := capKeys(keys, "")
 	// The candidates are read in batches, each in parallel and taken in key order, so the read stops at the batch that holds it.
@@ -444,6 +445,7 @@ func (r Reader) Status() (Status, error) {
 		if err != nil {
 			return st, err
 		}
+		keys = slices.DeleteFunc(keys, IsTryGroup) // a try's candidate is judged by its try, never as a check
 		sort.Strings(keys)
 		total := len(keys)
 		keys, cut := capKeys(keys, "")
@@ -14,6 +14,7 @@ import (
 	"time"

 	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-builder/buildrun"
+	"git.novox.be/novox/mesh-delivery/sdk/tryevent"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 )

@@ -27,6 +28,8 @@ const (
 	TryTool     = "checker_try"
 	TryReadTool = "checker_try_read"
 	TryEndTool  = "checker_try_end"
+	// TriesTool lists the tries that wait or run (OpenTries).
+	TriesTool = "checker_tries"
 	// TriesState is the checker's state of tries: the bucket mesh-delivery-checker_tries, keys try-<unix nanoseconds>.
 	TriesState  = "tries"
 	TriesBucket = delivery.CheckerModule + "_" + TriesState
@@ -62,18 +65,28 @@ var (

 // Try is the value of a tries key.
 type Try struct {
-	V          int    `json:"v"`
-	ID         string `json:"id"`
+	V  int    `json:"v"`
+	ID string `json:"id"`
+	// Repository, Head, Trunk and Branch are the first member's (the try's headline, and all a try of one repository
+	// names); Members are every member of the try, by repository: each an exact commit merged onto a trunk commit (a
+	// group try, issue 1921). A try written before members read as one member.
 	Repository string `json:"repository"`
 	// Head is the commit tried; Trunk the trunk commit it is merged onto, and Branch the trunk's branch when it was asked by name.
-	Head   string `json:"head"`
-	Trunk  string `json:"trunk"`
-	Branch string `json:"branch,omitempty"`
+	Head    string      `json:"head"`
+	Trunk   string      `json:"trunk"`
+	Branch  string      `json:"branch,omitempty"`
+	Members []TryMember `json:"members,omitempty"`
 	// Tests is a go test -run pattern: only those tests run, and nothing is kept. Level is unit or integration: only that
 	// level runs. Empty is every test of both levels.
 	Tests string `json:"tests,omitempty"`
 	Level string `json:"level,omitempty"`
 	State string `json:"state"`
+	// Told is true from the moment a whole try's start is said on the checker's stream until its end is said there: kept in the
+	// try's own state, so an end that is written and not said (the checker stopped between) is said when the checker starts.
+	Told bool `json:"told,omitempty"`
+	// Waiting is what the running try waits for now (its group's candidate from the indexer, ADR 0639 §5), empty when it waits for nothing;
+	// try-read gives it, so a try that sits still says why.
+	Waiting string `json:"waiting,omitempty"`
 	// Said is the try's report in words: what failed first, the tests run, kept and skipped per level, the time of each part.
 	Said string `json:"said,omitempty"`
 	// Took is the time from its start to its end, as Go writes a duration.
@@ -83,6 +96,11 @@ type Try struct {
 	Failed   []string                        `json:"failed,omitempty"`
 	Levels   map[string]delivery.LevelResult `json:"levels,omitempty"`
 	Machines []string                        `json:"machines,omitempty"`
+	// Composition is what the composition on every placed node came to (a whole try, not one narrowed to a level or to
+	// some tests), and Notes the words the check noted on its way (the manifests judged, the module graph, the kept
+	// verdicts taken): the same as a group's pull-request check reports.
+	Composition *delivery.Composition `json:"composition,omitempty"`
+	Notes       []string              `json:"notes,omitempty"`
 	// Asks are the ids of the asks the try put on the build seats' streams, each ending on the step key <node>.<id> of its
 	// build module: the delivery view counts those steps as a try's, not a candidate's check (build_usage).
 	Asks []string `json:"asks,omitempty"`
@@ -94,6 +112,23 @@ type Try struct {
 	Ended   time.Time `json:"ended,omitzero"`
 }

+// TryMember is one repository of a try: the exact commit asked, never the branch's head now, and the trunk commit it is
+// merged onto. Branch is the trunk's branch when the trunk was asked by name.
+type TryMember struct {
+	Repository string `json:"repository"`
+	Head       string `json:"head"`
+	Trunk      string `json:"trunk"`
+	Branch     string `json:"branch,omitempty"`
+}
+
+// MembersOf are the try's members: its Members, or the one its headline names.
+func (t Try) MembersOf() []TryMember {
+	if len(t.Members) > 0 {
+		return t.Members
+	}
+	return []TryMember{{Repository: t.Repository, Head: t.Head, Trunk: t.Trunk, Branch: t.Branch}}
+}
+
 // TryAsked is a TryStep's state before a build node took its ask: it waits in the seat's stream.
 const TryAsked = "asked"

@@ -148,6 +183,17 @@ func (w *tryWriter) heard(askID string, step *delivery.Step) {
 	}
 }

+// waiting writes what the try waits for now ("" when it waits for nothing).
+func (w *tryWriter) waiting(why string) {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+	if w.stopped || w.t.Waiting == why {
+		return
+	}
+	w.t.Waiting = why
+	w.write()
+}
+
 // write writes the record at the revision written last; a refusal stops the writes.
 func (w *tryWriter) write() {
 	data, err := encodeTry(w.t)
@@ -195,6 +241,7 @@ func DecodeTry(raw []byte) (Try, error) {
 	if !tryKeyOK.MatchString(t.ID) || t.Repository == "" || t.Head == "" || t.Trunk == "" {
 		return Try{}, errors.New("not a try: it names no id, repository, head or trunk")
 	}
+	t.Members = t.MembersOf()
 	return t, nil
 }

@@ -206,6 +253,14 @@ func encodeTry(t Try) ([]byte, error) {
 // TryAsk is what checker_try is given.
 type TryAsk struct {
 	Repository, Head, Trunk, Tests, Level string
+	// Members are the repositories of a group try, each an exact commit and, optionally, its trunk (a commit, or the
+	// trunk's branch for its head now); the single Repository, Head and Trunk above are one member. Both at once are refused.
+	Members []TryAskMember
+}
+
+// TryAskMember is one repository of a group try as it is asked.
+type TryAskMember struct {
+	Repository, Head, Trunk string
 }

 // TryStore is the tries state as the tools see it.
@@ -221,21 +276,16 @@ func NotChecked(repository string) error {
 	return fmt.Errorf("no level of %s is checked by the checker", repository)
 }

-// AskTry writes a new try, queued, and answers its id: a try of the same head that waits or runs is the answer to a second
-// ask, and a new try is refused while MaxTries tries run on a build node or MaxTriesWaiting wait for one. trunks are the
-// gate's trunk heads of every repository (source.main): a repository with none is no repository the checker checks. A trunk asked by name is its trunk head now.
-func AskTry(store TryStore, trunks map[string]string, a TryAsk, now time.Time) (string, error) {
+// tryMember checks one member as it is asked and resolves its trunk: the gate's trunk head of its repository, a commit
+// asked, or the trunk's branch (its head now). A repository with no trunk head is no repository the checker checks.
+func tryMember(trunks map[string]string, a TryAskMember) (TryMember, error) {
 	repo := strings.ToLower(strings.TrimSuffix(strings.TrimSpace(a.Repository), ".git"))
 	head := strings.ToLower(strings.TrimSpace(a.Head))
 	switch {
 	case !tryRepoOK.MatchString(repo) || strings.Contains(repo, ".."):
-		return "", fmt.Errorf("%q is not a repository, <owner>/<name>", a.Repository)
+		return TryMember{}, fmt.Errorf("%q is not a repository, <owner>/<name>", a.Repository)
 	case !tryHeadOK.MatchString(head):
-		return "", fmt.Errorf("the head %q is not a full commit, 40 or 64 hex digits", a.Head)
-	case a.Level != "" && a.Level != delivery.LevelUnit && a.Level != delivery.LevelIntegration:
-		return "", fmt.Errorf("the level %q is neither unit nor integration", a.Level)
-	case a.Tests != "" && !tryTestsOK.MatchString(a.Tests):
-		return "", fmt.Errorf("the tests %q are not a go test -run pattern", a.Tests)
+		return TryMember{}, fmt.Errorf("the head %q of %s is not a full commit, 40 or 64 hex digits", a.Head, repo)
 	}
 	trunkHead := ""
 	for r, h := range trunks {
@@ -244,20 +294,67 @@ func AskTry(store TryStore, trunks map[string]string, a TryAsk, now time.Time) (
 		}
 	}
 	if trunkHead == "" {
-		return "", NotChecked(repo)
+		return TryMember{}, NotChecked(repo)
 	}
-	t := Try{Repository: repo, Head: head, Tests: a.Tests, Level: a.Level, State: TryQueued, Asked: now.UTC()}
+	m := TryMember{Repository: repo, Head: head}
 	switch trunk := strings.TrimSpace(a.Trunk); {
 	case trunk == "":
-		t.Trunk = trunkHead
+		m.Trunk = trunkHead
 	case tryHeadOK.MatchString(strings.ToLower(trunk)):
-		t.Trunk = strings.ToLower(trunk)
+		m.Trunk = strings.ToLower(trunk)
 	case tryTrunkOK.MatchString(trunk) && !strings.Contains(trunk, ".."):
 		// The checker judges pull requests into the trunk alone (ADR 0484 clause 11): a branch named is the trunk's head now.
-		t.Trunk, t.Branch = trunkHead, trunk
+		m.Trunk, m.Branch = trunkHead, trunk
 	default:
-		return "", fmt.Errorf("the trunk %q is neither a full commit nor a branch", a.Trunk)
+		return TryMember{}, fmt.Errorf("the trunk %q of %s is neither a full commit nor a branch", a.Trunk, repo)
 	}
+	return m, nil
+}
+
+// sameMembers says whether two tries ask the same commits onto the same trunk commits.
+func sameMembers(a, b []TryMember) bool {
+	return slices.EqualFunc(a, b, func(x, y TryMember) bool {
+		return x.Repository == y.Repository && x.Head == y.Head && x.Trunk == y.Trunk
+	})
+}
+
+// AskTry writes a new try, queued, and answers its id: a try of the same commits that waits or runs is the answer to a second
+// ask, and a new try is refused while MaxTries tries run on a build node or MaxTriesWaiting wait for one. A try is a group of
+// one or more members (issue 1921), each an exact commit, never the branch's head now: a push after the ask changes nothing
+// of what is tried. trunks are the gate's trunk heads of every repository (source.main): a repository with none is no
+// repository the checker checks. A trunk asked by name is its trunk head now.
+func AskTry(store TryStore, trunks map[string]string, a TryAsk, now time.Time) (string, error) {
+	asked := a.Members
+	if a.Repository != "" || a.Head != "" || a.Trunk != "" {
+		if len(asked) > 0 {
+			return "", errors.New("name the members, or one repository with its head, not both")
+		}
+		asked = []TryAskMember{{Repository: a.Repository, Head: a.Head, Trunk: a.Trunk}}
+	}
+	if len(asked) == 0 {
+		return "", errors.New("name what to try: members (repository and head each), or a repository and its head")
+	}
+	switch {
+	case a.Level != "" && a.Level != delivery.LevelUnit && a.Level != delivery.LevelIntegration:
+		return "", fmt.Errorf("the level %q is neither unit nor integration", a.Level)
+	case a.Tests != "" && !tryTestsOK.MatchString(a.Tests):
+		return "", fmt.Errorf("the tests %q are not a go test -run pattern", a.Tests)
+	}
+	var members []TryMember
+	for _, m := range asked {
+		tm, err := tryMember(trunks, m)
+		if err != nil {
+			return "", err
+		}
+		if slices.ContainsFunc(members, func(o TryMember) bool { return o.Repository == tm.Repository }) {
+			return "", fmt.Errorf("%s is named twice: a try holds one commit of a repository", tm.Repository)
+		}
+		members = append(members, tm)
+	}
+	slices.SortFunc(members, func(x, y TryMember) int { return strings.Compare(x.Repository, y.Repository) })
+	first := members[0]
+	t := Try{Repository: first.Repository, Head: first.Head, Trunk: first.Trunk, Branch: first.Branch, Members: members,
+		Tests: a.Tests, Level: a.Level, State: TryQueued, Asked: now.UTC()}
 	keys, err := store.Keys()
 	if err != nil {
 		return "", fmt.Errorf("the tries cannot be listed: %w", err)
@@ -291,10 +388,10 @@ func AskTry(store TryStore, trunks map[string]string, a TryAsk, now time.Time) (
 		if !live[i] {
 			continue
 		}
-		if cur.Repository == t.Repository && cur.Head == t.Head && cur.Trunk == t.Trunk && cur.Tests == t.Tests && cur.Level == t.Level {
+		if sameMembers(cur.MembersOf(), t.Members) && cur.Tests == t.Tests && cur.Level == t.Level {
 			return cur.ID, nil
 		}
-		said := fmt.Sprintf("%s (%s@%.12s, %s)", cur.ID, cur.Repository, cur.Head, cur.State)
+		said := fmt.Sprintf("%s (%s, %s)", cur.ID, sayMembers(cur.MembersOf()), cur.State)
 		if cur.HoldsANode() {
 			holding = append(holding, said)
 		} else {
@@ -379,12 +476,50 @@ func EndTry(store TryEnder, id, why string, now time.Time) (Try, error) {
 	return t, nil
 }

+// IsTryGroup says a candidates key is the group of a try (the indexer makes the candidate of a group try's previews, for the
+// manifest validator and the composition): the try judges it, so the checker's check of candidates leaves it alone, writes
+// no verdict and owes the forge no status for it.
+func IsTryGroup(key string) bool { return tryKeyOK.MatchString(key) }
+
 // TryOptions narrow what a try runs; a pull request's check has none.
 type TryOptions struct {
 	Level string
 	Run   string
 }

+// Whole says the try runs everything a group's pull-request check runs (both levels of every member, the manifests judged by
+// the manifest validator, the module graph, the composition on every placed node): it is narrowed to neither a level nor
+// some tests. Such a try judges by the same code as the check, so the two cannot drift (issue 1921).
+func (o *TryOptions) Whole() bool { return o != nil && o.Level == "" && o.Run == "" }
+
+// TryCase is the case a try is judged as: one pull of the group per member at its exact commit, with no pull request number
+// (no ref: the commit is fetched as it is), the group named by the try's key, and the heads hash its candidate is keyed by.
+func TryCase(key string, t Try, watch func(string, *delivery.Step)) *Case {
+	cs := &Case{Key: key, Group: key, Watch: watch, Trunk: map[string]string{}, Queued: t.Asked, Progress: &Progress{},
+		Try: &TryOptions{Level: t.Level, Run: t.Tests}}
+	var heads []delivery.Head
+	for _, m := range t.MembersOf() {
+		cs.Pulls = append(cs.Pulls, Pull{Repository: m.Repository, Head: m.Head, Trunk: m.Trunk})
+		cs.Trunk[m.Repository] = m.Trunk
+		heads = append(heads, delivery.Head{Repository: m.Repository, Head: m.Head})
+	}
+	cs.HeadsHash, _ = delivery.HeadsHash(heads)
+	cs.Heads = cs.HeadsHash
+	return cs
+}
+
+// compositionMade says whether a composition was made; notMadeWords what it says when it was not.
+func compositionMade(c *delivery.Composition) bool {
+	return c != nil && c.State != delivery.CompositionNotRun
+}
+
+func notMadeWords(c *delivery.Composition) string {
+	if c == nil || c.Words == "" {
+		return "no reason was given"
+	}
+	return c.Words
+}
+
 // Tryer runs the tries: it takes a queued try, judges it through the same Judge as a pull request's check (a check ask, ADR
 // 0525 §1), and writes its end. It holds no timer: a try starts when its key is written.
 type Tryer struct {
@@ -396,7 +531,13 @@ type Tryer struct {
 	Now      func() time.Time
 	Logf     func(format string, args ...any)

+	// Say publishes an event of the checker's stream (tryevent.Started, tryevent.Ended) with its body; nil says nothing. The
+	// indexer, which hears them, writes and deletes the candidate of a whole try's group.
+	// It answers the publish's error, nil only when the stream acknowledged it: an end not acknowledged is said again.
+	Say func(ctx context.Context, event string, body tryevent.Event) error
+
 	mu       sync.Mutex
+	ending   map[string]bool // tries whose end is being said now
 	wg       sync.WaitGroup
 	inflight map[string]context.CancelFunc
 	seen     map[string]bool // looked at since this process started: a try left running is taken over the first time
@@ -436,6 +577,7 @@ func (tr *Tryer) Put(ctx context.Context, key string, value []byte) {
 			stop()
 		}
 		tr.mu.Unlock()
+		tr.sendEnd(ctx, key) // ended by hand while it ran, or its end was written and not said: the indexer drops its candidate
 		return
 	}
 	if tr.inflight[key] != nil || (t.State == TryRunning && tr.seen[key]) {
@@ -491,6 +633,7 @@ func (tr *Tryer) run(ctx context.Context, key string) {
 		return
 	}
 	t.State, t.Started = TryRunning, tr.now().UTC()
+	t.Told = (&TryOptions{Level: t.Level, Run: t.Tests}).Whole() // its start is said below; its end is owed from now on
 	data, err := encodeTry(t)
 	if err != nil {
 		return
@@ -502,12 +645,15 @@ func (tr *Tryer) run(ctx context.Context, key string) {
 		return
 	}
 	progress := &tryWriter{tr: tr, ctx: ctx, key: key, t: t, rev: rev}
-	cs := &Case{Key: key, Group: key, Watch: progress.heard,
-		Pulls:    []Pull{{Repository: t.Repository, Head: t.Head, Trunk: t.Trunk}},
-		Trunk:    map[string]string{t.Repository: t.Trunk},
-		Queued:   t.Asked,
-		Progress: &Progress{},
-		Try:      &TryOptions{Level: t.Level, Run: t.Tests}}
+	if t.Told {
+		started := tryevent.Event{ID: key}
+		for _, m := range t.MembersOf() {
+			started.Members = append(started.Members, tryevent.Member{Repository: m.Repository, Head: m.Head, Trunk: m.Trunk})
+		}
+		tr.say(ctx, tryevent.Started, started)
+	}
+	cs := TryCase(key, t, progress.heard)
+	cs.Wait = progress.waiting
 	judging := ctx
 	if tr.NotTaken > 0 {
 		judging = buildrun.NotTakenBound(ctx, tr.NotTaken)
@@ -517,12 +663,18 @@ func (tr *Tryer) run(ctx context.Context, key string) {
 		return // left running: the checker takes it over when it starts; or ended by hand, which wrote its end
 	}
 	t, rev = progress.end()
+	t.Waiting = ""
 	v := out.Verdict
 	t.Ended = tr.now().UTC()
 	t.Took = t.Ended.Sub(t.Started).Round(time.Second).String()
 	t.Levels, t.Machines, t.Asks = v.Levels, v.Machines, cs.Asks()
+	t.Composition = v.Composition
 	t.Said = Report(v, cs, cs.Pulls[0], out.Builds, out.Slowest, out.Judged)
-	for _, n := range cs.Notes() {
+	if len(cs.Pulls) > 1 {
+		t.Said = sayMembers(t.MembersOf()) + ": " + t.Said
+	}
+	t.Notes = cs.Notes()
+	for _, n := range t.Notes {
 		t.Said += " | " + n
 	}
 	switch {
@@ -532,6 +684,16 @@ func (tr *Tryer) run(ctx context.Context, key string) {
 		if IsLostAsk(v) || IsNotTaken(v) {
 			t.Failed = []string{v.Failed.Words}
 		}
+	case v.State == delivery.VerdictPass && cs.Try.Whole() && compositionMade(v.Composition) && strings.Contains(v.Composition.Words, delivery.ComposeNoAnswer):
+		// A node that gave no answer passes a group's check with a warning; a try that is to say the group composes says it
+		// did not, naming the node (ADR 0637 §3).
+		t.State = TryError
+		t.Failed = []string{"the composition was not made on every placed node: " + v.Composition.Words}
+	case v.State == delivery.VerdictPass && cs.Try.Whole() && !compositionMade(v.Composition):
+		// A whole try that judged the tests and not the manifests and the composition has not tried what its group's check
+		// judges: it is no pass, and it says why (failure must be loud). It is an error, not the change's failure.
+		t.State = TryError
+		t.Failed = []string{"the composition was not made: " + notMadeWords(v.Composition)}
 	case v.State == delivery.VerdictPass:
 		t.State = TryPass
 	default:
@@ -549,6 +711,97 @@ func (tr *Tryer) run(ctx context.Context, key string) {
 		return
 	}
 	tr.logf("%s: %s", key, t.State)
+	tr.sendEnd(ctx, key)
+}
+
+// sendEnd says the end of an ended try whose start was said (Told) with the state it ended in, then clears Told in the try's
+// own state; a checker that stopped between the two says it again at its start. Every end is said so: pass, fail, error and
+// by hand.
+func (tr *Tryer) sendEnd(ctx context.Context, key string) {
+	tr.mu.Lock()
+	if tr.ending[key] {
+		tr.mu.Unlock()
+		return
+	}
+	if tr.ending == nil {
+		tr.ending = map[string]bool{}
+	}
+	tr.ending[key] = true
+	tr.mu.Unlock()
+	defer func() { tr.mu.Lock(); delete(tr.ending, key); tr.mu.Unlock() }()
+	raw, rev, found, err := tr.Tries.Get(ctx, key)
+	if err != nil || !found {
+		return
+	}
+	t, err := DecodeTry(raw)
+	if err != nil || !t.Over() || !t.Told {
+		return
+	}
+	if tr.say(ctx, tryevent.Ended, tryevent.Event{ID: key, State: t.State}) != nil {
+		return // not acknowledged: Told stays, and the next Put or Reconsider says the end again
+	}
+	t.Told = false
+	data, err := encodeTry(t)
+	if err == nil {
+		_, err = tr.Tries.Update(ctx, key, data, rev)
+	}
+	if err != nil && !errors.Is(err, ErrConflict) {
+		tr.logf("%s: its end was said and Told could not be cleared: %v", key, err)
+	}
+}
+
+// say publishes a try event; a failure is said in the log (the indexer finds the open tries again at its start).
+func (tr *Tryer) say(ctx context.Context, event string, body tryevent.Event) error {
+	if tr.Say == nil {
+		return nil
+	}
+	err := tr.Say(ctx, event, body)
+	if err != nil {
+		tr.logf("%s of %s could not be said: %v", event, body.ID, err)
+	}
+	return err
+}
+
+// OpenTries are every try that waits or runs now: what checker_tries answers, so a part that missed an event (the indexer at
+// its start) finds them without reading the checker's state. All the keys are read (an old open try is as open as a new one), in
+// parallel.
+func OpenTries(store TryStore) ([]tryevent.Open, error) {
+	keys, err := store.Keys()
+	if err != nil {
+		return nil, fmt.Errorf("the tries cannot be listed: %w", err)
+	}
+	sort.Slice(keys, func(i, j int) bool {
+		if len(keys[i]) != len(keys[j]) {
+			return len(keys[i]) > len(keys[j])
+		}
+		return keys[i] > keys[j]
+	})
+	found := make([]*tryevent.Open, len(keys))
+	if err := parallel(len(keys), func(i int) error {
+		raw, err := store.Get(keys[i])
+		if err != nil || len(raw) == 0 {
+			return nil
+		}
+		t, err := DecodeTry(raw)
+		if err != nil || t.Over() {
+			return nil
+		}
+		o := tryevent.Open{ID: t.ID, State: t.State, Whole: (&TryOptions{Level: t.Level, Run: t.Tests}).Whole()}
+		for _, m := range t.MembersOf() {
+			o.Members = append(o.Members, tryevent.Member{Repository: m.Repository, Head: m.Head, Trunk: m.Trunk})
+		}
+		found[i] = &o
+		return nil
+	}); err != nil {
+		return nil, err
+	}
+	out := []tryevent.Open{} // none open is an empty list, never null: a reader tells it from no answer (issue 1921)
+	for _, o := range found {
+		if o != nil {
+			out = append(out, *o)
+		}
+	}
+	return out, nil
 }

 // judgeWithin runs a case within the bound (none when 0: the asks' steps are bounded from their start, ADR 0525 §6). A
@@ -579,6 +832,15 @@ func judgeWithin(ctx context.Context, j Judge, cs *Case, bound time.Duration) (O
 	return out, true
 }

+// sayMembers names a try's members, each repository at its short commit.
+func sayMembers(ms []TryMember) string {
+	var out []string
+	for _, m := range ms {
+		out = append(out, fmt.Sprintf("%s@%.12s", m.Repository, m.Head))
+	}
+	return strings.Join(out, " + ")
+}
+
 // orNone joins the tries said, or says none.
 func orNone(said []string) string {
 	if len(said) == 0 {
@@ -3,11 +3,14 @@ package check
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
+	"slices"
 	"strings"
 	"testing"
 	"time"

+	"git.novox.be/novox/mesh-delivery/sdk/tryevent"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 )

@@ -70,6 +73,25 @@ func TestATryIsAskedQueuedOncePerHeadAndAtMostFourAtOnce(t *testing.T) { // ADR
 	}
 	// Issue 1890: tries on a build node (a step of theirs running, or none named yet) and tries waiting for one (queued, or
 	// their asks not taken) are bounded apart, MaxTries and MaxTriesWaiting; the refusal names both counts.
+	// A group try is the same try whatever the order of its members; the commits asked are the commits tried.
+	group := TryAsk{Members: []TryAskMember{{Repository: repoSDK, Head: head2}, {Repository: repoA, Head: head1}}}
+	gid, err := AskTry(store, tryTrunks, group, at.Add(time.Second))
+	if err != nil || gid == id {
+		t.Fatalf("the group try = %q, %v, want a try of its own", gid, err)
+	}
+	group.Members[0], group.Members[1] = group.Members[1], group.Members[0]
+	if again, err := AskTry(store, tryTrunks, group, at.Add(time.Minute)); err != nil || again != gid {
+		t.Errorf("the group asked in another order answered %q, %v, want %q", again, err, gid)
+	}
+	if g := readTry(t, kv, gid); len(g.Members) != 2 || g.Members[0].Repository != repoA || g.Members[0].Head != head1 || g.Members[1].Trunk != trunkS {
+		t.Errorf("group try = %+v, want its members by repository at the commits asked", g.Members)
+	}
+	if open, err := OpenTries(store); err != nil || len(open) != 2 || !open[0].Whole || len(open[1].Members) != 2 && len(open[0].Members) != 2 {
+		t.Errorf("open tries = %+v, %v, want the two queued", open, err)
+	}
+	if !IsTryGroup(gid) || IsTryGroup("feat/x") || IsTryGroup("fix/1921-try-1") {
+		t.Errorf("which candidates keys are a try's group: %s is, a branch is not", gid)
+	}
 	onNode := func(i int) Try {
 		return Try{ID: fmt.Sprintf("try-%d", i), Repository: repoA, Head: fmt.Sprintf("%040x", i), Trunk: trunkA, State: TryRunning,
 			Steps: []TryStep{{Ask: "a", State: delivery.StepRunning}}}
@@ -112,59 +134,154 @@ func TestATryOfARepositoryWithNoCheckedLevelIsRefused(t *testing.T) { // the agr
 		}
 	}
 	for _, bad := range []TryAsk{{Repository: repoA, Head: "abc"}, {Repository: repoA, Head: head1, Level: "e2e"},
-		{Repository: repoA, Head: head1, Tests: "a b"}, {Repository: "x", Head: head1}, {Repository: repoA, Head: head1, Trunk: "-x"}} {
+		{Repository: repoA, Head: head1, Tests: "a b"}, {Repository: "x", Head: head1}, {Repository: repoA, Head: head1, Trunk: "-x"},
+		// A group try (issue 1921): members or one repository, never both or none; one commit per repository; every member checked.
+		{},
+		{Repository: repoA, Head: head1, Members: []TryAskMember{{Repository: repoSDK, Head: head2}}},
+		{Members: []TryAskMember{{Repository: repoA, Head: head1}, {Repository: repoA, Head: head2}}},
+		{Members: []TryAskMember{{Repository: repoA, Head: head1}, {Repository: repoSDK, Head: "main"}}},
+		{Members: []TryAskMember{{Repository: repoA, Head: head1}, {Repository: "novox/no-trunk", Head: head2}}}} {
 		if _, err := AskTry(store, tryTrunks, bad, time.Now()); err == nil {
 			t.Errorf("%+v was taken", bad)
 		}
 	}
 }

-func TestATryIsJudgedAsAPullRequestsHeadAndOwesTheForgeNothing(t *testing.T) { // ADR 0501 §5
+// fakeTryCandidates answers the indexer's candidate of a try's group from memory, recording the keys asked.
+type fakeTryCandidates struct {
+	cand  delivery.Candidate
+	err   error
+	asked []string
+	// during is called while the try waits for the candidate.
+	during func()
+}
+
+func (f *fakeTryCandidates) TryCandidate(_ context.Context, group, heads string, _ time.Duration) (delivery.Candidate, error) {
+	if f.during != nil {
+		f.during()
+	}
+	f.asked = append(f.asked, group+"."+heads)
+	return f.cand, f.err
+}
+
+// wholeBench makes the bench judge a whole try as the checker does: the composition on every placed node and the
+// indexer's candidate of the try's group.
+func wholeBench(b *bench, cand delivery.Candidate) (*fakeCompositions, *fakeTryCandidates) {
+	comps := &fakeCompositions{v: delivery.CompositionVerdict{State: delivery.CompositionPass, SDK: "v0.1.14-x", Machines: []string{"g14", "shanks"}, Took: 40}}
+	cands := &fakeTryCandidates{cand: cand}
+	b.ex.Compositions, b.ex.Candidates = comps, cands
+	return comps, cands
+}
+
+// A group try (issue 1921): several repositories each at the exact commit asked, judged by the code of a group's pull-request
+// check; the two cannot drift, and a later check of the same heads keeps what the try passed.
+func TestATryIsJudgedAsAGroupsCheckAndOwesTheForgeNothing(t *testing.T) { // ADR 0501 §5, issue 1921
 	ctx := context.Background()
 	kv := newMemKV()
-	id, err := AskTry(memTries{kv}, tryTrunks, TryAsk{Repository: repoA, Head: head1, Trunk: trunkA}, time.Now())
+	id, err := AskTry(memTries{kv}, tryTrunks, TryAsk{Members: []TryAskMember{{Repository: repoSDK, Head: head2, Trunk: trunkS}, {Repository: repoA, Head: head1, Trunk: trunkA}}}, time.Now())
 	if err != nil {
 		t.Fatal(err)
 	}
 	b := newBench(t)
+	comps, cands := wholeBench(b, delivery.Candidate{FPSet: "fps-of-the-try"})
 	written := &writtenTries{memKV: kv}
-	tr := &Tryer{Tries: written, Judge: b.ex}
+	var waiting string
+	cands.during = func() { waiting = readTry(t, kv, id).Waiting } // ADR 0639 §5: the stored try says what it waits for
+	var said []string
+	tr := &Tryer{Tries: written, Judge: b.ex, Say: func(_ context.Context, event string, e tryevent.Event) error {
+		said = append(said, fmt.Sprintf("%s %s %d %s", event, e.ID, len(e.Members), e.State))
+		return nil
+	}}
 	raw, _, _, _ := kv.Get(ctx, id)
 	tr.Put(ctx, id, raw)
 	tr.Wait()
+	// The indexer hears the start with the members at their commits, and the end (it writes and deletes the group's candidate).
+	if len(said) != 2 || said[0] != "try.started "+id+" 2 " || said[1] != "try.ended "+id+" 0 "+TryPass {
+		t.Errorf("events = %v, want the start with 2 members and the end", said)
+	}
+	// What the indexer reads: tryevent.Decode accepts the events as said and refuses a body that is no try's.
+	for _, row := range []struct {
+		name, event, body string
+		ok                bool
+	}{
+		{"a start with its members", tryevent.Started, `{"id":"` + id + `","members":[{"repository":"` + repoA + `","head":"` + head1 + `","trunk":"` + trunkA + `"}]}`, true},
+		{"an end with its state", tryevent.Ended, `{"id":"` + id + `","state":"pass"}`, true},
+		{"an id that is no try's", tryevent.Ended, `{"id":"pull-7","state":"pass"}`, false},
+		{"a start with no member", tryevent.Started, `{"id":"` + id + `"}`, false},
+		{"a body that is no JSON", tryevent.Ended, `try-7`, false},
+	} {
+		if e, err := tryevent.Decode(row.event, []byte(row.body)); (err == nil) != row.ok || (row.ok && e.ID != id) {
+			t.Errorf("Decode of %s = %+v, %v, want ok=%v", row.name, e, err, row.ok)
+		}
+	}
 	got := readTry(t, kv, id)
-	if got.State != TryPass || got.Took == "" || got.Head != head1 || got.Trunk != trunkA || got.Said == "" || got.Levels[delivery.LevelUnit].Run != 2 {
+	if !strings.Contains(waiting, "candidate") || got.Waiting != "" {
+		t.Errorf("waiting while the candidate was awaited = %q, after the end %q: want the reason, then none", waiting, got.Waiting)
+	}
+	if got.Told { // the end was said: nothing is owed
+		t.Errorf("the ended try still owes its end: %+v", got)
+	}
+	if open, err := OpenTries(memTries{kv}); err != nil || len(open) != 0 {
+		t.Errorf("open tries after the end = %v, %v", open, err)
+	} else if raw, _ := json.Marshal(open); string(raw) != "[]" { // issue 1921: none open is [] on the wire, never null
+		t.Errorf("none open is answered %s, want []", raw)
+	}
+	if got.State != TryPass || got.Took == "" || len(got.Members) != 2 || got.Members[0].Repository != repoA || got.Members[1].Head != head2 ||
+		got.Said == "" || got.Levels[delivery.LevelUnit].Run+got.Levels[delivery.LevelUnit].Kept != 4 { // the bench gives both members the same digests
 		t.Fatalf("try = %+v", got)
 	}
-	// Issue 1890: while it runs, the try names its ask as soon as it is put, and then where its step stands; the end
-	// keeps each ask's node and state.
-	if len(written.running) < 3 || len(written.running[1].Asks) != 1 || written.running[1].Steps[0].State != TryAsked ||
-		written.running[2].Steps[0].Node != "shanks" {
-		t.Errorf("the running try's writes = %+v, want its ask named while it ran, then its node", written.running)
+	if got.Composition == nil || got.Composition.State != delivery.CompositionPass || len(got.Machines) == 0 {
+		t.Errorf("the try's composition = %+v, want the composition on every placed node, as a check's", got.Composition)
 	}
-	if len(got.Steps) != 1 || got.Steps[0].Node != "shanks" || got.Steps[0].State != delivery.StepPassed {
-		t.Errorf("the ended try's steps = %+v", got.Steps)
+	// The same key the indexer's candidate of the group has: the try's id and the heads of its members.
+	if len(comps.asked) != 1 || comps.asked[0] != id || len(cands.asked) != 1 || !strings.HasPrefix(cands.asked[0], id+".") {
+		t.Errorf("composed %v, candidate asked %v, want the try's key %s", comps.asked, cands.asked, id)
 	}
-	// The try names the asks it put, so the delivery view counts their steps as a try's (build_usage).
-	if len(got.Asks) != 1 {
-		t.Errorf("asks = %v, want the one check ask the try put", got.Asks)
-	} else if _, err := delivery.AskStepKey("shanks", got.Asks[0]); err != nil {
-		t.Errorf("the try names %q, which is no ask id: %v", got.Asks[0], err)
+	// Issue 1890: while it runs, the try names its asks as soon as they are put, and then where each step stands.
+	if len(written.running) < 3 || len(written.running[1].Asks) != 1 || written.running[1].Steps[0].State != TryAsked {
+		t.Errorf("the running try's writes = %+v, want its ask named while it ran", written.running)
 	}
+	if len(got.Steps) != 2 || got.Steps[0].Node != "shanks" || got.Steps[0].State != delivery.StepPassed || len(got.Asks) != 2 {
+		t.Errorf("the ended try's steps = %+v, asks %v", got.Steps, got.Asks)
+	}
+	for _, a := range got.Asks { // the delivery view counts their steps as a try's (build_usage)
+		if _, err := delivery.AskStepKey("shanks", a); err != nil {
+			t.Errorf("the try names %q, which is no ask id: %v", a, err)
+		}
+	}
+	// Each member is fetched at the exact commit asked, merged onto its own trunk, with no pull request's ref.
 	fetch := b.steps.tool("fetch")
-	if len(fetch) != 1 || fetch[0].args["commit"] != head1 || fetch[0].args["base"] != trunkA || fetch[0].args["ref"] != "" {
-		t.Errorf("fetch = %+v, want the head merged onto the trunk, with no pull request's ref", fetch)
+	if len(fetch) != 2 {
+		t.Fatalf("fetch = %+v, want one per member", fetch)
 	}
-	if keys, _ := b.prev.Keys(ctx); len(keys) != 0 {
-		t.Errorf("a try wrote the previews %v", keys)
+	for _, f := range fetch {
+		want := map[string][2]string{repoA: {head1, trunkA}, repoSDK: {head2, trunkS}}[f.args["repository"].(string)]
+		if f.args["commit"] != want[0] || f.args["base"] != want[1] || f.args["ref"] != "" {
+			t.Errorf("fetch = %+v, want the exact commit %s merged onto %s", f.args, want[0], want[1])
+		}
+	}
+	// A whole try writes the merge previews the indexer makes its candidate from; it writes no status and asks no Approve.
+	if keys, _ := b.prev.Keys(ctx); len(keys) != 2 {
+		t.Errorf("a whole try wrote the previews %v, want one per member", keys)
 	}
 	// An ended try is not run again.
 	raw, _, _, _ = kv.Get(ctx, id)
 	tr.Put(ctx, id, raw)
 	tr.Wait()
-	if n := len(b.steps.tool("fetch")); n != 1 {
+	if n := len(b.steps.tool("fetch")); n != 2 {
 		t.Errorf("an ended try was fetched again: %d fetches", n)
 	}
+	// The kept verdicts: what the try passed is kept under the digests of the merged trees, so the pull-request check of
+	// the same head on the same trunk runs none of it again (and a push of other code runs only what changed).
+	before := len(b.steps.tool("test"))
+	out := b.judge(t, caseOf(t, pullOf(repoA, 7, head1)))
+	if out.Verdict.State != delivery.VerdictPass || out.Verdict.Levels[delivery.LevelUnit].Kept == 0 || out.Verdict.Levels[delivery.LevelUnit].Run != 0 ||
+		out.Verdict.Levels[delivery.LevelIntegration].Run != 0 {
+		t.Errorf("the check of the tried head = %+v, want everything the try passed kept and nothing run", out.Verdict.Levels)
+	}
+	if after := len(b.steps.tool("test")); after != before {
+		t.Errorf("the check of the tried head ran %d test steps, want none: the try's passes are kept", after-before)
+	}
 }

 func TestATryOfOneLevelAndSomeTestsRunsThemAloneAndKeepsNothing(t *testing.T) {
@@ -175,10 +292,16 @@ func TestATryOfOneLevelAndSomeTestsRunsThemAloneAndKeepsNothing(t *testing.T) {
 		t.Fatal(err)
 	}
 	b := newBench(t)
-	tr := &Tryer{Tries: kv, Judge: b.ex}
+	tr := &Tryer{Tries: kv, Judge: b.ex, Say: func(context.Context, string, tryevent.Event) error {
+		t.Error("a try of one level and some tests said an event: it has no candidate")
+		return nil
+	}}
 	raw, _, _, _ := kv.Get(ctx, id)
 	tr.Put(ctx, id, raw)
 	tr.Wait()
+	if open, _ := OpenTries(memTries{kv}); len(open) != 0 {
+		t.Errorf("open = %v", open)
+	}
 	tests := b.steps.tool("test")
 	if len(tests) != 1 || tests[0].args["level"] != delivery.LevelIntegration || tests[0].args["run"] != "TestBus|TestStore" {
 		t.Fatalf("tests = %+v, want the integration level alone with the run pattern", tests)
@@ -192,6 +315,24 @@ func TestATryOfOneLevelAndSomeTestsRunsThemAloneAndKeepsNothing(t *testing.T) {
 	if got := readTry(t, kv, id); got.State != TryPass || !strings.Contains(got.Said, "only the tests TestBus|TestStore") {
 		t.Errorf("try = %+v", got)
 	}
+	t.Run("a try of one level keeps only that level", func(t *testing.T) {
+		kv := newMemKV()
+		id, _ := AskTry(memTries{kv}, tryTrunks, TryAsk{Repository: repoA, Head: head1, Level: delivery.LevelUnit}, time.Now())
+		b := newBench(t)
+		tr := &Tryer{Tries: kv, Judge: b.ex}
+		raw, _, _, _ := kv.Get(ctx, id)
+		tr.Put(ctx, id, raw)
+		tr.Wait()
+		keys, _ := b.kept.Keys(ctx)
+		if got := readTry(t, kv, id); got.State != TryPass || len(keys) == 0 {
+			t.Fatalf("try = %+v, kept %v", got, keys)
+		}
+		for _, k := range keys {
+			if !strings.HasPrefix(k, delivery.LevelUnit+".") {
+				t.Errorf("a try of the unit level kept %s", k)
+			}
+		}
+	})
 }

 func TestAFailingTryNamesWhatFailedAndAStepThatCannotRunIsAnError(t *testing.T) {
@@ -208,26 +349,135 @@ func TestAFailingTryNamesWhatFailedAndAStepThatCannotRunIsAnError(t *testing.T)
 		!strings.Contains(got.Failed[1], "integration: fixture/failing/bad.TestThreeIsFour") { // both levels ran (the operator, 2026-11-02)
 		t.Errorf("try = %+v", got)
 	}
+	// A whole try that could not judge the manifests and the composition is no pass; a failed composition is named beside
+	// the failed tests (the group's check does as much), and a candidate of other heads is not the try's.
+	for _, row := range []struct {
+		name        string
+		cand        *fakeTryCandidates
+		comp        delivery.CompositionVerdict
+		state, said string
+	}{
+		{name: "the indexer wrote no candidate", cand: &fakeTryCandidates{err: errors.New("the indexer wrote no candidate within 5m0s")}, state: TryError, said: "the indexer wrote no candidate within 5m0s"},
+		{name: "a node that gave no composition answer", cand: &fakeTryCandidates{}, comp: delivery.CompositionVerdict{State: delivery.CompositionPass, SDK: "x", Warnings: []string{"g14: " + delivery.ComposeNoAnswer}},
+			state: TryError, said: "g14: " + delivery.ComposeNoAnswer},
+		{name: "a composition refused on a node", cand: &fakeTryCandidates{}, comp: delivery.CompositionVerdict{State: delivery.CompositionFail, Machine: "g14", Words: "not composed on g14: web: needs a state mail does not keep"},
+			state: TryFail, said: "not composed on g14: web: needs a state mail does not keep"},
+	} {
+		kv := newMemKV()
+		b := newBench(t)
+		comps, _ := wholeBench(b, delivery.Candidate{})
+		b.ex.Candidates, comps.v = row.cand, row.comp
+		if row.comp.State == "" {
+			comps.v.State = delivery.CompositionPass
+		}
+		id, _ := AskTry(memTries{kv}, tryTrunks, TryAsk{Repository: repoA, Head: head1}, time.Now())
+		var ends []string
+		tr := &Tryer{Tries: kv, Judge: b.ex, Say: func(_ context.Context, event string, e tryevent.Event) error {
+			if event == tryevent.Ended {
+				ends = append(ends, e.State)
+			}
+			return nil
+		}}
+		raw, _, _, _ := kv.Get(ctx, id)
+		tr.Put(ctx, id, raw)
+		tr.Wait()
+		if len(ends) != 1 || ends[0] != row.state { // every end says its state: error as well as fail
+			t.Errorf("%s: ends said = %v, want once %s", row.name, ends, row.state)
+		}
+		if got := readTry(t, kv, id); got.State != row.state || !strings.Contains(strings.Join(got.Failed, " | ")+got.Said, row.said) {
+			t.Errorf("%s: try = %s, failed %v, said %q, want %s naming %q", row.name, got.State, got.Failed, got.Said, row.state, row.said)
+		}
+	}
 	// No build node is no error since R4g: the try's ask waits in the check stream until a node pulls it (ADR 0525 §4).
 }

 func TestATryLeftRunningIsTakenOver(t *testing.T) {
 	ctx := context.Background()
-	kv := newMemKV()
-	id, _ := AskTry(memTries{kv}, tryTrunks, TryAsk{Repository: repoA, Head: head1}, time.Now())
-	// Left running by a checker that stopped.
-	raw, rev, _, _ := kv.Get(ctx, id)
-	cur, _ := DecodeTry(raw)
-	cur.State = TryRunning
-	data, _ := encodeTry(cur)
-	if _, err := kv.Update(ctx, id, data, rev); err != nil {
-		t.Fatal(err)
-	}
-	b := newBench(t)
-	tr := &Tryer{Tries: kv, Judge: b.ex}
-	tr.Reconsider(ctx)
-	tr.Wait()
-	if got := readTry(t, kv, id); got.State != TryPass {
-		t.Errorf("the try left running = %+v, want taken over and passed", got)
+	// Whether the start was said is in the try's own state (Told), so a checker that starts later says the end of a try it did
+	// not start, whatever way the try ended.
+	for _, row := range []struct {
+		name      string
+		told      bool
+		failFirst bool // the stream does not acknowledge the first end said
+		after     func(t *testing.T, kv *memKV, id string)
+		ends      []string
+	}{
+		{name: "the first publish of the end is not acknowledged", told: true, failFirst: true, ends: []string{TryPass}},
+		{name: "left running after its start was said", told: true, ends: []string{TryPass}},
+		{name: "left running with no start said", told: false, ends: []string{TryPass}},
+		{name: "ended by hand after the start was said", told: true, ends: []string{TryError}, after: func(t *testing.T, kv *memKV, id string) {
+			if _, err := EndTry(endable{kv}, id, "stuck", time.Now()); err != nil {
+				t.Fatal(err)
+			}
+		}},
+	} {
+		t.Run(row.name, func(t *testing.T) {
+			kv := newMemKV()
+			id, _ := AskTry(memTries{kv}, tryTrunks, TryAsk{Repository: repoA, Head: head1}, time.Now())
+			// Left running by a checker that stopped.
+			raw, rev, _, _ := kv.Get(ctx, id)
+			cur, _ := DecodeTry(raw)
+			cur.State, cur.Told = TryRunning, row.told
+			data, _ := encodeTry(cur)
+			if _, err := kv.Update(ctx, id, data, rev); err != nil {
+				t.Fatal(err)
+			}
+			if row.after != nil {
+				row.after(t, kv, id)
+			}
+			b := newBench(t)
+			wholeBench(b, delivery.Candidate{})
+			var ends []string
+			failed := false
+			tr := &Tryer{Tries: kv, Judge: b.ex, Say: func(_ context.Context, event string, e tryevent.Event) error {
+				if event == tryevent.Ended {
+					if row.failFirst && !failed {
+						failed = true
+						return errors.New("the stream did not acknowledge")
+					}
+					ends = append(ends, e.State)
+				}
+				return nil
+			}}
+			tr.Reconsider(ctx)
+			tr.Wait()
+			if row.failFirst && !readTry(t, kv, id).Told {
+				t.Errorf("an end the stream did not acknowledge cleared Told: it is never said again")
+			}
+			tr.Reconsider(ctx) // said once: the second look finds nothing owed
+			tr.Wait()
+			if row.after == nil {
+				if got := readTry(t, kv, id); got.State != TryPass {
+					t.Errorf("the try left running = %+v, want taken over and passed", got)
+				}
+			}
+			if !slices.Equal(ends, row.ends) || readTry(t, kv, id).Told {
+				t.Errorf("ends said = %v, want %v, and nothing owed after", ends, row.ends)
+			}
+		})
 	}
+	// An ended try is kept TryKeep and removed by the next Reconsider after.
+	t.Run("an ended try is kept seven days", func(t *testing.T) {
+		kv := newMemKV()
+		id, _ := AskTry(memTries{kv}, tryTrunks, TryAsk{Repository: repoA, Head: head1}, time.Now())
+		raw, rev, _, _ := kv.Get(ctx, id)
+		cur, _ := DecodeTry(raw)
+		ended := time.Now()
+		cur.State, cur.Ended = TryPass, ended
+		data, _ := encodeTry(cur)
+		if _, err := kv.Update(ctx, id, data, rev); err != nil {
+			t.Fatal(err)
+		}
+		now := ended.Add(TryKeep - time.Hour)
+		tr := &Tryer{Tries: kv, Now: func() time.Time { return now }}
+		tr.Reconsider(ctx)
+		if _, _, found, _ := kv.Get(ctx, id); !found {
+			t.Fatal("the try was removed before TryKeep")
+		}
+		now = ended.Add(TryKeep + time.Hour)
+		tr.Reconsider(ctx)
+		if _, _, found, _ := kv.Get(ctx, id); found {
+			t.Error("the try was kept past TryKeep")
+		}
+	})
 }
@@ -130,14 +130,40 @@ func TestManifestDeclarations(t *testing.T) { // 1678/AC1
 	if m.SecretsOwner != "mesh-delivery-checker" {
 		t.Errorf("secrets-owner = %q", m.SecretsOwner)
 	}
-	// The checker says each time it wrote a preview or a status, so the indexer's and the forge bridge's watches find the buckets (ADR 0484 clauses 2 and 3).
-	if want := []stream{{Name: "checks", Events: []string{"preview.**", "owed.**"}}}; !reflect.DeepEqual(m.Streams, want) {
+	// The checker says each time it wrote a preview or a status, so the indexer's and the forge bridge's watches find the buckets (ADR 0484 clauses 2 and 3). A whole try says try.started with its members and try.ended, so the indexer writes and deletes the candidate of its group (issue 1921).
+	if want := []stream{{Name: "checks", Events: []string{"preview.**", "owed.**", "try.**"}}}; !reflect.DeepEqual(m.Streams, want) {
 		t.Errorf("streams = %+v, want %+v", m.Streams, want)
 	}
+	// Only the checker's account publishes try.* on its stream checks: the stream is declared by its owner alone, and no other
+	// module of the repository declares a stream carrying a try event (the indexer and the others only consume them).
+	siblings, err := filepath.Glob("../*/module.json")
+	if err != nil || len(siblings) < 2 {
+		t.Fatalf("the sibling manifests = %v, %v", siblings, err)
+	}
+	for _, f := range siblings {
+		raw, err := os.ReadFile(f)
+		if err != nil {
+			t.Fatal(err)
+		}
+		var other struct {
+			Module  string   `json:"module"`
+			Streams []stream `json:"streams"`
+		}
+		if err := json.Unmarshal(raw, &other); err != nil {
+			t.Fatalf("%s: %v", f, err)
+		}
+		for _, st := range other.Streams {
+			for _, e := range st.Events {
+				if strings.HasPrefix(e, "try.") && other.Module != m.Module {
+					t.Errorf("%s declares the stream %s with %s: only the checker's account publishes try events", other.Module, st.Name, e)
+				}
+			}
+		}
+	}
 	// The read tools (issue 1686) are served by the tools bundle, not by the checker's process.
 	// The try's tools (ADR 0501 §5; the end by hand, issue 734) beside them: mesh-controller's try calls them. A lost check
 	// is asked again by hand (checker_ask_again).
-	if want := []string{"checker_ask_again", "checker_kept", "checker_previews", "checker_pull", "checker_status", "checker_try", "checker_try_end", "checker_try_read", "checker_verdicts"}; !reflect.DeepEqual(sorted(m.Tools), want) {
+	if want := []string{"checker_ask_again", "checker_kept", "checker_previews", "checker_pull", "checker_status", "checker_tries", "checker_try", "checker_try_end", "checker_try_read", "checker_verdicts"}; !reflect.DeepEqual(sorted(m.Tools), want) {
 		t.Errorf("tools = %v, want %v", m.Tools, want)
 	}
 	// The try is the checker's own seat's verbs (ADR 0547 §10, issue 774), served beside the tools by the same code.
@@ -18,7 +18,7 @@
    "mesh-build-node.toolchain.reported"
  ],
  "streams": [
-    { "name": "checks", "events": ["preview.**", "owed.**"] }
+    { "name": "checks", "events": ["preview.**", "owed.**", "try.**"] }
  ],
  "state": [
    { "name": "asks", "history": 1 },
@@ -56,6 +56,7 @@
    "checker_previews",
    "checker_pull",
    "checker_status",
+    "checker_tries",
    "checker_try",
    "checker_try_end",
    "checker_try_read",
@@ -0,0 +1,266 @@
+// Command mesh-delivery-forge-bridge-tools serves the forge bridge's tools (novox/hq ADR 0633 §4, issue 1585): the runtime
+// launches it for a call. bridge_groups reads the delivery groups the gate holds and what the bridge kept of their ends;
+// bridge_group_end_again writes an ask into the bridge's state end-asks and waits for the bridge's answer there, since the
+// bridge is the other program and serves no request subject (ADR 0437 §4).
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"maps"
+	"os"
+	"slices"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	stdio "git.novox.be/novox/mesh-sdk/go"
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+
+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
+
+	"mesh-delivery-forge-bridge/internal/bridge"
+	"mesh-delivery-forge-bridge/internal/groups"
+)
+
+// Tool names.
+const (
+	GroupsTool   = "bridge_groups"
+	EndAgainTool = "bridge_group_end_again"
+	// MergedTool answers the merged message of a merge on request (issue 1585).
+	MergedTool = "bridge_merged_message"
+)
+
+// asker writes an end-asks value and waits for the bridge's answer to it.
+type asker func(key string, value []byte) (groups.EndAsk, error)
+
+// Tools are the bridge's tools: groupsRead reads the groups the gate holds with what the bridge kept of them.
+func Tools(ask asker, now func() time.Time, groupsRead func() ([]groups.Row, []string, error), merged func(repository, merge string) (json.RawMessage, error)) []stdio.Tool {
+	str := func(args map[string]any, k string) string { s, _ := args[k].(string); return strings.TrimSpace(s) }
+	return []stdio.Tool{
+		{Name: MergedTool,
+			Description: "The merged message of one merge, asked again (issue 1585): the message the bridge wrote on its stream FORGE when the " +
+				"pull request was merged into the trunk, built the same way from the forge (the merge commit's trees and the manifests " +
+				"and lock files of its module directories) and from the gate's merges state (the pull request's number, head and " +
+				"group). For the indexer, which asks it when it takes in a held merge it does not hold in memory (a restart, a new " +
+				"build), and the ask-again a lost message lacked. About 0.5 MB for a repository of many modules. Answers {message} " +
+				"with the forge message whole, or why it cannot: the gate holds no merge with that commit, or the forge did not answer.",
+			Input: map[string]any{"type": "object", "required": []string{"repository", "merge"}, "properties": map[string]any{
+				"repository": map[string]any{"type": "string", "description": "the repository, owner/name, as the forge names it"},
+				"merge":      map[string]any{"type": "string", "description": "the merge commit, 40 hex digits"}}},
+			Run: func(args map[string]any) (any, error) {
+				raw, err := merged(str(args, "repository"), str(args, "merge"))
+				if err != nil {
+					return nil, err
+				}
+				return map[string]any{"message": raw}, nil
+			}},
+		{Name: GroupsTool,
+			Description: "The delivery groups the gate holds (more than one member), each with its members' merge state and whether each " +
+				"merged message is written on the forge stream, and whether the group's end (forge.group.merged) is written: ended, " +
+				"or open with why (gathered, or merged and its end not written yet). An open group with every member merged is " +
+				"what bridge_group_end_again says the end of. Each group names its last end ask (who, why, when) and the bridge's " +
+				"answer to it, from the state end-asks. A group's name narrows it to that group; open lists only open ones.",
+			Input: map[string]any{"type": "object", "properties": map[string]any{
+				"group": map[string]any{"type": "string", "description": "only this group, by the name the gate keys it"},
+				"open":  map[string]any{"type": "boolean", "description": "only the groups whose end is not written"}}},
+			Run: func(args map[string]any) (any, error) {
+				rows, unread, err := groupsRead()
+				if err != nil {
+					return nil, err
+				}
+				only, _ := args["open"].(bool)
+				group := str(args, "group")
+				kept := rows[:0]
+				for _, r := range rows {
+					if (group != "" && r.Group != group) || (only && !r.Open) {
+						continue
+					}
+					kept = append(kept, r)
+				}
+				return map[string]any{"groups": kept, "unread": unread}, nil
+			}},
+		{Name: EndAgainTool,
+			Description: "Say a delivery group's end (forge.group.merged) again, by hand, for a group whose end the indexer did not take " +
+				"in (a group bridge_groups names as merged with its end not written, or one the indexer waits for). The bridge " +
+				"writes it again from the gate's merges, with the time appended to the message id so the stream does not drop it as " +
+				"a duplicate; the indexer takes an end for a group it already took in without changing anything. Refused while " +
+				"a member is not merged or its merged message is not written. Answers whether it was written.",
+			Input: map[string]any{"type": "object", "required": []string{"group"}, "properties": map[string]any{
+				"group": map[string]any{"type": "string", "description": "the group, by the name the gate keys it"},
+				"why":   map[string]any{"type": "string", "description": "why its end is said again, in plain words"}}},
+			Run: func(args map[string]any) (any, error) {
+				key, value, err := groups.NewEndAsk(str(args, "group"), str(args, "why"), stdio.CallerOf(args), now())
+				if err != nil {
+					return nil, err
+				}
+				a, err := ask(key, value)
+				if err != nil {
+					return nil, err
+				}
+				return map[string]any{"group": a.Group, "written": a.Written, "answer": a.Answer, "by": a.By, "why": a.Why}, nil
+			}},
+	}
+}
+
+// MergedOf is the merged message of the merge of repository at commit merge, as the bridge writes it: the pull request's
+// number, head and group from the gate's merges (raw, by key), the rest from the forge through trees and files
+// (bridge.MergedMessage), and, for a member of a delivery group, the group and its members as the process sets them.
+func MergedOf(raws map[string][]byte, repository, merge string, trees bridge.Trees, files bridge.Files) (json.RawMessage, error) {
+	owner, repo, ok := strings.Cut(repository, "/")
+	if !ok || owner == "" || repo == "" {
+		return nil, fmt.Errorf("%q is not owner/name", repository)
+	}
+	for _, key := range slices.Sorted(maps.Keys(raws)) {
+		m, err := delivery.DecodeMerge(raws[key])
+		if err != nil {
+			continue
+		}
+		at := slices.IndexFunc(m.Pulls, func(p delivery.MergePull) bool {
+			return delivery.SameRepository(p.Repository, repository) && p.Commit == merge
+		})
+		if at < 0 {
+			continue
+		}
+		p := m.Pulls[at]
+		msg, err := bridge.MergedMessage(owner, repo, p.Number, m.Group, p.Head.Head, merge, trees, files)
+		if err != nil {
+			return nil, fmt.Errorf("the merged message of %s at %s cannot be built: %w", repository, merge, err)
+		}
+		f, err := forgemsg.DecodeForge(msg.Data)
+		if err != nil {
+			return nil, err
+		}
+		if _, approved := m.Approved[delivery.ApprovedKey(f.Repository, f.Number)]; approved && len(m.Approved) >= 2 {
+			f.Group, f.Members = m.Group, groups.MembersOf(m)
+		}
+		out, err := forgemsg.EncodeForge(f)
+		return out, err
+	}
+	return nil, fmt.Errorf("the gate's merges hold no merge of %s with the commit %s, so its pull request is not known", repository, merge)
+}
+
+// read is the groups the gate holds with what the bridge kept of them: their ends in performed, and the last ask of
+// each in end-asks with the bridge's answer.
+func read(merges, performed, asks stdio.KeptState) ([]groups.Row, []string, error) {
+	keys, err := merges.Keys()
+	if err != nil {
+		return nil, nil, fmt.Errorf("the gate's merges cannot be listed: %w", err)
+	}
+	raws := map[string][]byte{}
+	for _, k := range keys {
+		e, err := merges.Get(k)
+		if err != nil || e == nil {
+			continue
+		}
+		raws[k] = e.Value
+	}
+	pkeys, err := performed.Keys()
+	if err != nil {
+		return nil, nil, fmt.Errorf("the bridge's performed state cannot be listed: %w", err)
+	}
+	published, ended := map[string]bool{}, map[string]uint64{}
+	for _, k := range pkeys {
+		switch {
+		case strings.HasPrefix(k, "published."):
+			published[k] = true
+		case strings.HasPrefix(k, "groups."):
+			if e, err := performed.Get(k); err == nil && e != nil {
+				rev, _ := strconv.ParseUint(strings.TrimSpace(string(e.Value)), 10, 64)
+				ended[strings.TrimPrefix(k, "groups.")] = rev
+			}
+		}
+	}
+	akeys, err := asks.Keys()
+	if err != nil {
+		return nil, nil, fmt.Errorf("the bridge's state %s cannot be listed: %w", groups.EndAsksState, err)
+	}
+	askRaws := map[string][]byte{}
+	for _, k := range akeys {
+		if e, err := asks.Get(k); err == nil && e != nil {
+			askRaws[k] = e.Value
+		}
+	}
+	rows, unread := groups.Rows(raws, published, ended, askRaws)
+	return rows, unread, nil
+}
+
+// askEnd writes the end-asks value at key and waits, on a watch of the key, at most bound for the bridge's answer.
+func askEnd(s stdio.KeptState, bound time.Duration) asker {
+	return func(key string, value []byte) (groups.EndAsk, error) {
+		answered := make(chan groups.EndAsk, 1)
+		var rev uint64
+		var mu sync.Mutex
+		take := func(revision uint64, v []byte) {
+			mu.Lock()
+			mine := rev
+			mu.Unlock()
+			if mine == 0 || revision <= mine {
+				return
+			}
+			if a, err := groups.DecodeEndAsk(v); err == nil && a.Done() {
+				select {
+				case answered <- a:
+				default:
+				}
+			}
+		}
+		if err := s.Watch(key, func(c stdio.StateChange) error {
+			if c.Op == "put" {
+				take(c.Revision, c.Value)
+			}
+			return nil
+		}); err != nil {
+			return groups.EndAsk{}, fmt.Errorf("watching %s.%s: %w", groups.EndAsksState, key, err)
+		}
+		r, err := s.Put(key, json.RawMessage(value))
+		if err != nil {
+			return groups.EndAsk{}, fmt.Errorf("the ask could not be written to %s: %w", groups.EndAsksBucket, err)
+		}
+		mu.Lock()
+		rev = r
+		mu.Unlock()
+		if e, err := s.Get(key); err == nil && e != nil {
+			take(e.Revision, e.Value)
+		}
+		wait, cancel := context.WithTimeout(context.Background(), bound) // a context's bound, no timer (ADR 0437 §8)
+		defer cancel()
+		select {
+		case a := <-answered:
+			return a, nil
+		case <-wait.Done():
+			return groups.EndAsk{}, fmt.Errorf("the bridge did not answer within %s: its answer will be in %s.%s", bound, groups.EndAsksBucket, key)
+		}
+	}
+}
+
+// askCaller calls a tool as this bundle's module, through the runtime (stdio.Ask), the module's own invokes granting it.
+func askCaller(_ context.Context, key string, body any) (json.RawMessage, error) {
+	return stdio.Ask(key, body)
+}
+
+func main() {
+	merges, performed, asks := stdio.State(delivery.GateModule+".merges"), stdio.State(groups.PerformedState), stdio.State(groups.EndAsksState)
+	tools := Tools(askEnd(asks, 25*time.Second), time.Now,
+		func() ([]groups.Row, []string, error) { return read(merges, performed, asks) },
+		func(repository, merge string) (json.RawMessage, error) {
+			keys, err := merges.Keys()
+			if err != nil {
+				return nil, fmt.Errorf("the gate's merges cannot be listed: %w", err)
+			}
+			raws := map[string][]byte{}
+			for _, k := range keys {
+				if e, err := merges.Get(k); err == nil && e != nil {
+					raws[k] = e.Value
+				}
+			}
+			ctx := context.Background()
+			return MergedOf(raws, repository, merge, bridge.TreesVia(ctx, askCaller), bridge.FilesVia(ctx, askCaller))
+		})
+	if err := stdio.Serve("", tools); err != nil {
+		fmt.Fprintf(os.Stderr, "[mesh-delivery-forge-bridge-tools] %v\n", err)
+		os.Exit(1)
+	}
+}
@@ -0,0 +1,190 @@
+package main
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"strings"
+	"testing"
+	"time"
+
+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+
+	"mesh-delivery-forge-bridge/internal/bridge"
+
+	"mesh-delivery-forge-bridge/internal/groups"
+)
+
+// 1585/T18, T19 (ADR 0633 §4): bridge_groups names each group the gate holds with its members' state and whether its end is
+// written (open or ended, with why), narrowed by group and by open; bridge_group_end_again writes an ask naming the group,
+// who asked and why, and answers what the bridge answered.
+func TestTheBridgeToolsReadTheGroupsAndAskTheEndAgain(t *testing.T) {
+	h1, h2 := strings.Repeat("1", 40), strings.Repeat("2", 40)
+	c1, c2 := strings.Repeat("c", 40), strings.Repeat("d", 40)
+	enc := func(group string, state2 delivery.MergeState, c string) []byte {
+		v, err := delivery.EncodeMerge(delivery.Merge{Group: group, Ask: "ask", Approved: map[string]string{"novox/a@1": h1, "novox/b@2": h2},
+			Pulls: []delivery.MergePull{{Head: delivery.Head{Repository: "novox/a", Number: 1, Head: h1}, State: delivery.MergeMerged, Commit: c1},
+				{Head: delivery.Head{Repository: "novox/b", Number: 2, Head: h2}, State: state2, Commit: c}}})
+		if err != nil {
+			t.Fatal(err)
+		}
+		return v
+	}
+	lone, _ := delivery.EncodeMerge(delivery.Merge{Group: "solo", Ask: "ask", Approved: map[string]string{"novox/a@5": h1},
+		Pulls: []delivery.MergePull{{Head: delivery.Head{Repository: "novox/a", Number: 5, Head: h1}, State: delivery.MergeMerged, Commit: c1}}})
+	merges := map[string][]byte{"ended": enc("ended", delivery.MergeMerged, c2), "ready": enc("ready", delivery.MergeMerged, c2),
+		"gathered": enc("gathered", delivery.MergeMerging, ""), "solo": lone, "bad": []byte("{")}
+	performed := map[string]bool{}
+	for _, c := range []string{c1, c2} {
+		performed[groups.PublishedKey("novox/a", 1, c)], performed[groups.PublishedKey("novox/b", 2, c)] = true, true
+	}
+	// The state end-asks keeps the last ask of the group ready, answered, and one that does not read.
+	answeredAsk, _ := json.Marshal(groups.EndAsk{V: 1, Group: "ready", Why: "lost", By: "lead@shanks", At: time.Date(2026, 11, 4, 22, 0, 0, 0, time.UTC),
+		Written: true, Answer: "the end of the group is written again", Answered: time.Date(2026, 11, 4, 22, 0, 1, 0, time.UTC)})
+	asks := map[string][]byte{"ready": answeredAsk, "gathered": []byte("{")}
+	var asked groups.EndAsk
+	var askedKey string
+	ask := func(key string, value []byte) (groups.EndAsk, error) {
+		askedKey = key
+		a, err := groups.DecodeEndAsk(value)
+		a.Written, a.Answer, a.Answered = true, "the end of the group is written again", time.Now()
+		asked = a
+		return a, err
+	}
+	tools := Tools(ask, func() time.Time { return time.Date(2026, 11, 4, 23, 0, 0, 0, time.UTC) },
+		func() ([]groups.Row, []string, error) {
+			rows, unread := groups.Rows(merges, performed, map[string]uint64{"ended": 7}, asks)
+			return rows, unread, nil
+		}, nil)
+	call := func(name string, args map[string]any) any {
+		for _, tl := range tools {
+			if tl.Name == name {
+				out, err := tl.Run(args)
+				if err != nil {
+					t.Fatalf("%s: %v", name, err)
+				}
+				return out
+			}
+		}
+		t.Fatalf("no tool %s", name)
+		return nil
+	}
+	rowsOf := func(args map[string]any) map[string]groups.Row {
+		raw, _ := json.Marshal(call(GroupsTool, args))
+		var out struct {
+			Groups []groups.Row `json:"groups"`
+			Unread []string     `json:"unread"`
+		}
+		if err := json.Unmarshal(raw, &out); err != nil {
+			t.Fatal(err)
+		}
+		m := map[string]groups.Row{}
+		for _, r := range out.Groups {
+			m[r.Group] = r
+		}
+		if len(args) == 0 && strings.Join(out.Unread, " ") != "bad end-asks.gathered" {
+			t.Errorf("unread = %v, want bad and end-asks.gathered", out.Unread)
+		}
+		return m
+	}
+	all := rowsOf(map[string]any{})
+	if len(all) != 3 || !all["ended"].Ended || all["ended"].EndedAt != 7 {
+		t.Fatalf("groups = %+v", all)
+	}
+	if r := all["ready"]; !r.Open || !strings.Contains(r.Words, "bridge_group_end_again") || !r.Members[1].Published {
+		t.Errorf("ready = %+v, want open, merged and published, its end the thing to say", r)
+	}
+	if a := all["ready"].LastEndAsk; a == nil || a.By != "lead@shanks" || a.Why != "lost" || !a.Written || a.Answer == "" || all["ended"].LastEndAsk != nil {
+		t.Errorf("ready's last end ask = %+v, ended's %+v: want ready's ask and its answer, none for ended", a, all["ended"].LastEndAsk)
+	}
+	if r := all["gathered"]; !r.Open || !strings.Contains(r.Words, "gathered") || r.Members[1].State != string(delivery.MergeMerging) {
+		t.Errorf("gathered = %+v", r)
+	}
+	if open := rowsOf(map[string]any{"open": true}); len(open) != 2 || open["ended"].Group != "" {
+		t.Errorf("open = %+v, want ready and gathered", open)
+	}
+	if one := rowsOf(map[string]any{"group": "ready"}); len(one) != 1 {
+		t.Errorf("group ready = %+v", one)
+	}
+	out := call(EndAgainTool, map[string]any{"group": "ready", "why": "the indexer never took it in"}).(map[string]any)
+	if askedKey != "ready" || asked.Group != "ready" || asked.Why != "the indexer never took it in" || out["written"] != true {
+		t.Errorf("the ask %q %+v, answered %v", askedKey, asked, out)
+	}
+	for _, tl := range tools {
+		if tl.Name == EndAgainTool {
+			if _, err := tl.Run(map[string]any{}); err == nil {
+				t.Error("an ask naming no group was taken")
+			}
+		}
+	}
+
+	// 1585: bridge_merged_message answers the merged message as the bridge publishes it: for a lone pull request the same bytes
+	// the event gives through Convert, for a member of a delivery group those with its group and members set as the process
+	// sets them; a merge the gate does not hold, or a forge that does not answer, is said.
+	t.Run("bridge_merged_message answers the merged message as published", func(t *testing.T) {
+		h1, h2 := strings.Repeat("1", 40), strings.Repeat("2", 40)
+		c1, c2 := strings.Repeat("c", 40), strings.Repeat("d", 40)
+		trees := func(owner, repo, sha string) (string, map[string]string, error) {
+			return "root-" + sha[:4], map[string]string{"": "r", "modules/a": "ta-" + sha[:4]}, nil
+		}
+		files := func(owner, repo, path, ref string) ([]byte, error) {
+			if strings.HasSuffix(path, "module.json") {
+				return []byte(`{"module":"a"}`), nil
+			}
+			return nil, bridge.ErrNotFound
+		}
+		published := func(repo string, number int, head, branch, merge string) forgemsg.Forge {
+			body, _ := json.Marshal(map[string]any{"owner": "novox", "repo": repo, "number": number, "head": branch, "head_sha": head, "base": "main", "merge_commit_sha": merge})
+			msg, err := bridge.Convert(bridge.MergedSubject, body, trees, files)
+			if err != nil {
+				t.Fatal(err)
+			}
+			f, err := forgemsg.DecodeForge(msg.Data)
+			if err != nil {
+				t.Fatal(err)
+			}
+			return f
+		}
+		lone, _ := delivery.EncodeMerge(delivery.Merge{Group: "solo", Ask: "a", Approved: map[string]string{"novox/a@5": h1},
+			Pulls: []delivery.MergePull{{Head: delivery.Head{Repository: "novox/a", Number: 5, Head: h1}, State: delivery.MergeMerged, Commit: c1}}})
+		group, _ := delivery.EncodeMerge(delivery.Merge{Group: "feat/g", Ask: "a", Approved: map[string]string{"novox/a@6": h1, "novox/b@7": h2},
+			Pulls: []delivery.MergePull{{Head: delivery.Head{Repository: "novox/a", Number: 6, Head: h1}, State: delivery.MergeMerged, Commit: c1},
+				{Head: delivery.Head{Repository: "novox/b", Number: 7, Head: h2}, State: delivery.MergeMerging}}})
+		for _, c := range []struct {
+			name       string
+			raws       map[string][]byte
+			repository string
+			merge      string
+			want       forgemsg.Forge
+			fail       string
+		}{
+			{name: "a lone pull request", raws: map[string][]byte{"solo": lone}, repository: "novox/a", merge: c1, want: published("a", 5, h1, "solo", c1)},
+			{name: "a member of a group", raws: map[string][]byte{"feat~g": group}, repository: "novox/a", merge: c1, want: func() forgemsg.Forge {
+				f := published("a", 6, h1, "feat/g", c1)
+				f.Group, f.Members = "feat/g", []delivery.Head{{Repository: "novox/a", Number: 6, Head: h1}, {Repository: "novox/b", Number: 7, Head: h2}}
+				return f
+			}()},
+			{name: "a merge the gate does not hold", raws: map[string][]byte{"solo": lone, "bad": []byte("{")}, repository: "novox/a", merge: c2, fail: "hold no merge"},
+		} {
+			t.Run(c.name, func(t *testing.T) {
+				raw, err := MergedOf(c.raws, c.repository, c.merge, trees, files)
+				if c.fail != "" {
+					if err == nil || !strings.Contains(err.Error(), c.fail) {
+						t.Fatalf("err %v, want %q", err, c.fail)
+					}
+					return
+				}
+				want, _ := forgemsg.EncodeForge(c.want)
+				if err != nil || !bytes.Equal(raw, want) {
+					t.Fatalf("err %v, answer\n%s\nwant the published message\n%s", err, raw, want)
+				}
+			})
+		}
+		if _, err := MergedOf(map[string][]byte{"solo": lone}, "novox/a", c1, func(string, string, string) (string, map[string]string, error) {
+			return "", nil, errors.New("the forge does not answer")
+		}, files); err == nil || !strings.Contains(err.Error(), "does not answer") {
+			t.Errorf("a forge that does not answer: %v", err)
+		}
+	})
+}
@@ -5,7 +5,6 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"regexp"
 	"strings"
 	"time"

@@ -66,58 +65,12 @@ func callerOn(nc *nats.Conn, user string) caller {
 	}
 }

-// commitTreesTool is the forge's tool for a commit's trees (mesh-catalog modules/gitea, issue 1234): arguments owner,
-// repo and sha, answer {root, trees}, the root directory spelled "" (1234/AC4).
-const commitTreesTool = "gitea.gitea_commit_trees"
-
 // treesVia asks the forge for a commit's trees through call.
 func treesVia(ctx context.Context, call caller) bridge.Trees {
-	return func(owner, repo, sha string) (string, map[string]string, error) {
-		raw, err := call(ctx, commitTreesTool, map[string]string{"owner": owner, "repo": repo, "sha": sha})
-		if err != nil {
-			return "", nil, err
-		}
-		var a struct {
-			Root  string            `json:"root"`
-			Trees map[string]string `json:"trees"`
-		}
-		if err := json.Unmarshal(raw, &a); err != nil {
-			return "", nil, fmt.Errorf("the answer of %s is not {root, trees}: %w", commitTreesTool, err)
-		}
-		if a.Root == "" {
-			return "", nil, fmt.Errorf("the answer of %s names no root tree", commitTreesTool)
-		}
-		return a.Root, a.Trees, nil
-	}
+	return bridge.TreesVia(ctx, bridge.Caller(call))
 }

-// getFileTool is the forge's tool for one file at a ref (mesh-catalog modules/gitea tools/index.ts gitea_get_file):
-// arguments owner, repo, path and ref, answer {file: {path, ref, sha, size, content}}, the content decoded to text
-// (client.ts getFile). A path the forge does not have fails with `Gitea API <path>: 404 <body>` (client.ts request).
-const getFileTool = "gitea.gitea_get_file"
-
-// notFound is how the forge's error says 404 (client.ts request: `Gitea API ${path}: ${status} ${text}`; client.ts:670
-// recognises it as /: 404 /).
-var notFound = regexp.MustCompile(`: 404 `)
-
 // filesVia asks the forge for a file through call. A file the forge says is not there is bridge.ErrNotFound.
 func filesVia(ctx context.Context, call caller) bridge.Files {
-	return func(owner, repo, path, ref string) ([]byte, error) {
-		raw, err := call(ctx, getFileTool, map[string]string{"owner": owner, "repo": repo, "path": path, "ref": ref})
-		if err != nil {
-			if notFound.MatchString(err.Error()) {
-				return nil, fmt.Errorf("%w: %v", bridge.ErrNotFound, err)
-			}
-			return nil, err
-		}
-		var a struct {
-			File *struct {
-				Content *string `json:"content"`
-			} `json:"file"`
-		}
-		if err := json.Unmarshal(raw, &a); err != nil || a.File == nil || a.File.Content == nil {
-			return nil, fmt.Errorf("the answer of %s is not {file: {content}}: %v", getFileTool, err)
-		}
-		return []byte(*a.File.Content), nil
-	}
+	return bridge.FilesVia(ctx, bridge.Caller(call))
 }
@@ -9,6 +9,7 @@ import (
 	"strings"
 	"testing"

+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 )

@@ -120,8 +121,8 @@ func TestARefusedActIsWrittenOnForgeOnceAndNotRetried(t *testing.T) { // 1341/AC
 	if len(pub.subjects) != 1 || pub.subjects[0] != "mesh.stream.mesh-delivery-forge-bridge.event.forge.novox.mesh-delivery.refused" {
 		t.Fatalf("published on %v", pub.subjects)
 	}
-	m, err := delivery.DecodeForge(pub.data[0])
-	if err != nil || m.Kind != delivery.ForgeRefused || m.Act != "comment.1" || m.Number != 12 || m.Head != headA || m.Words != "the pull request is locked" {
+	m, err := forgemsg.DecodeForge(pub.data[0])
+	if err != nil || m.Kind != forgemsg.ForgeRefused || m.Act != "comment.1" || m.Number != 12 || m.Head != headA || m.Words != "the pull request is locked" {
 		t.Errorf("message %+v err %v", m, err)
 	}
 	f.refuse = nil
@@ -188,8 +189,8 @@ func TestARefusedMergeIsWrittenOnForgeOnceAndNotRetried(t *testing.T) { // 1342/
 	if len(f.calls) != 1 || len(pub.data) != 1 {
 		t.Fatalf("calls %d messages %d, want one each", len(f.calls), len(pub.data))
 	}
-	m, err := delivery.DecodeForge(pub.data[0])
-	if err != nil || m.Kind != delivery.ForgeRefused || m.Repository != "novox/mesh-delivery" || m.Number != 12 || m.Head != headA ||
+	m, err := forgemsg.DecodeForge(pub.data[0])
+	if err != nil || m.Kind != forgemsg.ForgeRefused || m.Repository != "novox/mesh-delivery" || m.Number != 12 || m.Head != headA ||
 		m.Act != "merge" || m.Words != "novox/mesh-delivery#12 is not merged: its head moved" {
 		t.Errorf("message %+v err %v", m, err)
 	}
@@ -0,0 +1,61 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"time"
+
+	"github.com/nats-io/nats.go/jetstream"
+
+	"mesh-delivery-forge-bridge/internal/groups"
+)
+
+// endAsked answers one value of the state end-asks (the tool bridge_group_end_again, ADR 0633 §4): a value not yet answered
+// says the group's end again from the gate's merges, with the ask's time appended to the message id so the stream's duplicate
+// window does not drop it, and is written back by compare-and-set at its revision with whether it was written. A value
+// answered already (this bridge's own write) is left.
+func (g *grouper) endAsked(ctx context.Context, kv jetstream.KeyValue, key string, rev uint64, value []byte) {
+	a, err := groups.DecodeEndAsk(value)
+	if err != nil {
+		g.logger.Printf("%s.%s holds what is not an end ask, left: %v", groups.EndAsksState, key, err)
+		return
+	}
+	if a.Done() {
+		return
+	}
+	a = g.answerEnd(ctx, key, a, time.Now())
+	g.logger.Printf("the end of the group %q said again by %s (%s): %s", a.Group, a.By, a.Why, a.Answer)
+	data, err := json.Marshal(a)
+	if err != nil {
+		return
+	}
+	if _, err := kv.Update(ctx, key, data, rev); err != nil && !errors.Is(err, jetstream.ErrKeyExists) && !errors.Is(err, jetstream.ErrKeyRevisionMismatch) {
+		g.logger.Printf("%s.%s: the answer could not be written: %v", groups.EndAsksState, key, err)
+	}
+}
+
+// readMerges reads one key of the gate's merges state.
+func (g *grouper) readMerges(ctx context.Context, key string) ([]byte, uint64, bool, error) {
+	if g.merges == nil {
+		return nil, 0, false, errors.New("the bridge does not read the gate's merges (its bucket was not there at the start)")
+	}
+	value, rev, found, err := g.merges(ctx, key)
+	return value, rev, found, err
+}
+
+// answerEnd says the group's end again for an ask and returns the ask with its answer.
+func (g *grouper) answerEnd(ctx context.Context, key string, a groups.EndAsk, at time.Time) groups.EndAsk {
+	a.Answered = at.UTC()
+	switch merges, mrev, found, err := g.readMerges(ctx, key); {
+	case err != nil:
+		a.Answer = "the gate's merges " + key + " cannot be read: " + err.Error()
+	case !found:
+		a.Answer = "the gate holds no merge of the group " + a.Group
+	case g.end(ctx, key, mrev, merges, groups.AgainStamp(a.At)):
+		a.Written, a.Answer = true, "the end of the group is written again"
+	default:
+		a.Answer = "the end is not written: a member is not merged or its merged message is not written, or FORGE refused it (the bridge's journal says which)"
+	}
+	return a
+}
@@ -0,0 +1,178 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"log"
+	"slices"
+
+	"github.com/nats-io/nats.go/jetstream"
+
+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+
+	groupkeys "mesh-delivery-forge-bridge/internal/groups"
+)
+
+// A delivery group's merges reach the indexer together (novox/hq ADR 0633 §4): the bridge sets the group on each
+// member's merged message, from the gate's merges state it reads (ADR 0437 §8), and once every approved member is
+// merged and its merged message written on FORGE it says the group's end, forge.group.merged, once.
+//
+// What it keeps of it is in its state performed, beside the gate's keys it acted on: `published.<hash>` for each
+// member's merged message written (the hash is the first 16 hex digits of the sha256 of `<repository>#<number>@<merge>`),
+// and `groups.<merges key>` once the group's end is written, its value the revision of the gate's merges key it was
+// worked out from. A group whose end is not written yet is open (bridge_groups reads them).
+
+// merges reads one key of the gate's merges state.
+type mergesRead func(ctx context.Context, key string) (value []byte, rev uint64, found bool, err error)
+
+// grouper sets a member's group and says a group's end.
+type grouper struct {
+	merges mergesRead
+	send   func(ctx context.Context, subject string, data []byte, id string) error // writes on FORGE with the message id
+	done   revisions
+	logger *log.Logger
+}
+
+// sendVia writes on FORGE through pub, with the message id.
+func sendVia(pub publisher) func(context.Context, string, []byte, string) error {
+	return func(ctx context.Context, subject string, data []byte, id string) error {
+		_, err := pub.Publish(ctx, subject, data, jetstream.WithMsgID(id))
+		return err
+	}
+}
+
+func kvMerges(kv jetstream.KeyValue) mergesRead {
+	return func(ctx context.Context, key string) ([]byte, uint64, bool, error) {
+		e, err := kv.Get(ctx, key)
+		if errors.Is(err, jetstream.ErrKeyNotFound) {
+			return nil, 0, false, nil
+		}
+		if err != nil {
+			return nil, 0, false, err
+		}
+		return e.Value(), e.Revision(), true, nil
+	}
+}
+
+// groupOf is the gate's merge of the group a merged message's branch names, when the message's pull request is one of
+// its approved members and the group has more than one: a lone pull request is no group.
+func (g *grouper) groupOf(ctx context.Context, f forgemsg.Forge) (delivery.Merge, uint64, bool) {
+	if g == nil || g.merges == nil || f.Branch == "" {
+		return delivery.Merge{}, 0, false
+	}
+	key, err := delivery.MergesKey(f.Branch)
+	if err != nil {
+		return delivery.Merge{}, 0, false
+	}
+	value, rev, found, err := g.merges(ctx, key)
+	if err != nil {
+		g.logger.Printf("%s#%d: the gate's merges.%s cannot be read, so its merged message names no group: %v", f.Repository, f.Number, key, err)
+		return delivery.Merge{}, 0, false
+	}
+	if !found {
+		return delivery.Merge{}, 0, false
+	}
+	m, err := delivery.DecodeMerge(value)
+	if err != nil {
+		g.logger.Printf("%s#%d: the gate's merges.%s is not a merge, so its merged message names no group: %v", f.Repository, f.Number, key, err)
+		return delivery.Merge{}, 0, false
+	}
+	if _, ok := m.Approved[delivery.ApprovedKey(f.Repository, f.Number)]; !ok || len(m.Approved) < 2 {
+		return delivery.Merge{}, 0, false
+	}
+	return m, rev, true
+}
+
+// member sets the group and its approved members on a merged message's body (ADR 0633 §4); any other body, and a
+// merge of no group, is left as it is.
+func (g *grouper) member(ctx context.Context, data []byte) ([]byte, forgemsg.Forge, bool) {
+	f, err := forgemsg.DecodeForge(data)
+	if err != nil || f.Kind != forgemsg.ForgeMerged {
+		return data, f, false
+	}
+	m, _, ok := g.groupOf(ctx, f)
+	if !ok {
+		return data, f, false
+	}
+	f.Group, f.Members = m.Group, groupkeys.MembersOf(m)
+	out, err := forgemsg.EncodeForge(f)
+	if err != nil {
+		g.logger.Printf("%s#%d: its merged message cannot name the group %q, written without: %v", f.Repository, f.Number, m.Group, err)
+		return data, f, false
+	}
+	return out, f, true
+}
+
+// published keeps that a member's merged message is written, and says the group's end when it was the last.
+func (g *grouper) published(ctx context.Context, f forgemsg.Forge) {
+	if err := g.done.Put(ctx, groupkeys.PublishedKey(f.Repository, f.Number, f.Merge), 1); err != nil {
+		g.logger.Printf("%s#%d: that its merged message is written is not kept, so the group's end waits for the next act: %v", f.Repository, f.Number, err)
+		return
+	}
+	key, err := delivery.MergesKey(f.Branch)
+	if err != nil {
+		return
+	}
+	value, rev, found, err := g.merges(ctx, key)
+	if err != nil || !found {
+		return
+	}
+	g.ended(ctx, key, rev, value)
+}
+
+// ended says the group's end (forge.group.merged) once every approved member of the gate's merge is merged and its
+// merged message written, after the last of them; never on a refusal (ADR 0441 §3: a held group merges on from it).
+// It is written once per group: `groups.<key>` in performed says it was. again says it is written again by hand
+// (bridge_group_end_again), with the time appended to the message id, so the duplicate window does not drop it.
+func (g *grouper) ended(ctx context.Context, key string, rev uint64, value []byte) {
+	g.end(ctx, key, rev, value, "")
+}
+
+func (g *grouper) end(ctx context.Context, key string, rev uint64, value []byte, again string) bool {
+	m, err := delivery.DecodeMerge(value)
+	if err != nil || len(m.Approved) < 2 {
+		return false
+	}
+	if again == "" {
+		if _, seen, err := g.done.Get(ctx, groupkeys.Key(key)); err == nil && seen {
+			return false
+		}
+	}
+	end := forgemsg.ForgeGroupEnd{Group: m.Group}
+	for _, member := range groupkeys.MembersOf(m) {
+		at := slices.IndexFunc(m.Pulls, func(p delivery.MergePull) bool {
+			return delivery.SameRepository(p.Repository, member.Repository) && p.Number == member.Number
+		})
+		if at < 0 || m.Pulls[at].Commit == "" {
+			return false // not every member is merged (a merge commit is written only for a merged pull): the group stays gathered
+		}
+		if _, ok, err := g.done.Get(ctx, groupkeys.PublishedKey(member.Repository, member.Number, m.Pulls[at].Commit)); err != nil || !ok {
+			return false // its merged message is not written yet: said when it is (published)
+		}
+		end.Members = append(end.Members, forgemsg.GroupMerge{Repository: member.Repository, Number: member.Number, Merge: m.Pulls[at].Commit})
+	}
+	// The members in the order the gate merged them, so the last commit names the end.
+	slices.SortStableFunc(end.Members, func(a, b forgemsg.GroupMerge) int {
+		return slices.IndexFunc(m.Pulls, func(p delivery.MergePull) bool { return p.Commit == a.Merge }) -
+			slices.IndexFunc(m.Pulls, func(p delivery.MergePull) bool { return p.Commit == b.Merge })
+	})
+	data, err := forgemsg.EncodeForgeGroupEnd(end)
+	if err != nil {
+		g.logger.Printf("the end of the group %q cannot be written: %v", m.Group, err)
+		return false
+	}
+	id := groupkeys.EndID(m.Group, end.Members[len(end.Members)-1].Merge, "")
+	if again != "" {
+		id += "." + again
+	}
+	if err := g.send(ctx, forgeSubject(forgemsg.ForgeGroupEndEvent), data, id); err != nil {
+		g.logger.Printf("the end of the group %q is not written on FORGE, written at the gate's next write or by bridge_group_end_again: %v", m.Group, err)
+		return false
+	}
+	if err := g.done.Put(ctx, groupkeys.Key(key), rev); err != nil {
+		g.logger.Printf("the end of the group %q is written and not kept: the stream's duplicate window drops a second one: %v", m.Group, err)
+	}
+	g.logger.Printf("the end of the group %q is written: %d members merged, the last %s", m.Group, len(end.Members), end.Members[len(end.Members)-1].Merge)
+	return true
+}
@@ -0,0 +1,141 @@
+package main
+
+import (
+	"bytes"
+	"context"
+	"log"
+	"strings"
+	"testing"
+	"time"
+
+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+
+	groupkeys "mesh-delivery-forge-bridge/internal/groups"
+)
+
+// idPub records the subjects, bodies and message ids it is handed.
+type idPub struct {
+	subjects, ids []string
+	data          [][]byte
+}
+
+func (p *idPub) send(_ context.Context, subject string, data []byte, id string) error {
+	p.subjects, p.data, p.ids = append(p.subjects, subject), append(p.data, data), append(p.ids, id)
+	return nil
+}
+
+func TestAGroupsMembersNameItAndItsEndIsSaidOnce(t *testing.T) { // 1585/T16, T17, T19 (ADR 0633 §4)
+	ctx := context.Background()
+	h1, h2 := strings.Repeat("1", 40), strings.Repeat("2", 40)
+	c1, c2 := strings.Repeat("c", 40), strings.Repeat("d", 40)
+	merge := func(states ...delivery.MergePull) []byte {
+		v, err := delivery.EncodeMerge(delivery.Merge{Group: "feat/take-in", Ask: "ask", Pulls: states,
+			Approved: map[string]string{"novox/mesh-sdk@37": h1, "novox/mesh-delivery@9": h2}})
+		if err != nil {
+			t.Fatal(err)
+		}
+		return v
+	}
+	sdk := func(state delivery.MergeState, commit, words string) delivery.MergePull {
+		return delivery.MergePull{Head: delivery.Head{Repository: "novox/mesh-sdk", Number: 37, Head: h1}, State: state, Commit: commit, Words: words}
+	}
+	dlv := func(state delivery.MergeState, commit string) delivery.MergePull {
+		return delivery.MergePull{Head: delivery.Head{Repository: "novox/mesh-delivery", Number: 9, Head: h2}, State: state, Commit: commit}
+	}
+	gate := map[string][]byte{}
+	var logs bytes.Buffer
+	pub, done := &idPub{}, memRevisions{}
+	g := &grouper{send: pub.send, done: done, logger: log.New(&logs, "", 0),
+		merges: func(_ context.Context, key string) ([]byte, uint64, bool, error) {
+			v, ok := gate[key]
+			return v, 7, ok, nil
+		}}
+	mergedOf := func(repo string, number int, head, commit string) []byte {
+		data, err := forgemsg.EncodeForge(forgemsg.Forge{Kind: forgemsg.ForgeMerged, Repository: repo, Branch: "feat/take-in", Number: number, Head: head, Merge: commit, Root: "r"})
+		if err != nil {
+			t.Fatal(err)
+		}
+		return data
+	}
+	// A lone pull request's merged message carries no group.
+	if _, f, ok := g.member(ctx, mergedOf("novox/hq", 4, h1, c1)); ok || f.Group != "" {
+		t.Errorf("a lone pull request names the group %q", f.Group)
+	}
+	// The first member: its message names the group and both members; the group is not ended.
+	gate["feat/take-in"] = merge(sdk(delivery.MergeMerged, c1, ""), dlv(delivery.MergeMerging, ""))
+	data, f, ok := g.member(ctx, mergedOf("novox/mesh-sdk", 37, h1, c1))
+	if back, err := forgemsg.DecodeForge(data); !ok || err != nil || back.Group != "feat/take-in" || len(back.Members) != 2 {
+		t.Fatalf("a member's message: %+v %v", back, err)
+	}
+	g.published(ctx, f)
+	// A refusal of the other member is no end (ADR 0441 §3: the group merges on from it later).
+	gate["feat/take-in"] = merge(sdk(delivery.MergeMerged, c1, ""), delivery.MergePull{Head: delivery.Head{Repository: "novox/mesh-delivery", Number: 9, Head: h2}, State: delivery.MergeRefused, Words: "405"})
+	g.ended(ctx, "feat/take-in", 8, gate["feat/take-in"])
+	// Merged on at the gate before its merged message is written: still no end; then its message ends the group.
+	gate["feat/take-in"] = merge(sdk(delivery.MergeMerged, c1, ""), dlv(delivery.MergeMerged, c2))
+	g.ended(ctx, "feat/take-in", 9, gate["feat/take-in"])
+	if len(pub.subjects) != 0 {
+		t.Fatalf("an end before every member's merged message is written: %v", pub.subjects)
+	}
+	_, f, _ = g.member(ctx, mergedOf("novox/mesh-delivery", 9, h2, c2))
+	g.published(ctx, f)
+	g.ended(ctx, "feat/take-in", 10, gate["feat/take-in"]) // a later write of the gate says no second end
+	if len(pub.subjects) != 1 || pub.subjects[0] != "mesh.stream.mesh-delivery-forge-bridge.event.forge.group.merged" || pub.ids[0] != "group-end.feat/take-in."+c2 {
+		t.Fatalf("ends %v ids %v, want one forge.group.merged with id group-end.feat/take-in.%s", pub.subjects, pub.ids, c2)
+	}
+	end, err := forgemsg.DecodeForgeGroupEnd(pub.data[0])
+	if err != nil || len(end.Members) != 2 || end.Members[0].Merge != c1 || end.Members[1].Merge != c2 {
+		t.Errorf("the end = %+v %v, want both members in their merge order", end, err)
+	}
+	if rev, ok := done[groupkeys.Key("feat/take-in")]; !ok || rev != 7 {
+		t.Errorf("performed %v: want groups.feat/take-in kept", done)
+	}
+	// Again by hand: written once more, its id not the first's.
+	if !g.end(ctx, "feat/take-in", 10, gate["feat/take-in"], "20261104T2300") || pub.ids[1] == pub.ids[0] {
+		t.Errorf("the end again by hand: ids %v", pub.ids)
+	}
+	// 1585/T19: an ask to say a group's end again is answered by the bridge from the gate's merges, with the ask's time on
+	// the message id; not written while a member is not merged, with the reason; not for a group the gate does not hold.
+	pull := func(repo string, n int, head string, state delivery.MergeState, commit string) delivery.MergePull {
+		return delivery.MergePull{Head: delivery.Head{Repository: repo, Number: n, Head: head}, State: state, Commit: commit}
+	}
+	askMerge := func(second delivery.MergeState, commit2 string) []byte {
+		v, err := delivery.EncodeMerge(delivery.Merge{Group: "feat/take-in", Ask: "ask", Approved: map[string]string{"novox/mesh-sdk@37": h1, "novox/mesh-delivery@9": h2},
+			Pulls: []delivery.MergePull{pull("novox/mesh-sdk", 37, h1, delivery.MergeMerged, c1), pull("novox/mesh-delivery", 9, h2, second, commit2)}})
+		if err != nil {
+			t.Fatal(err)
+		}
+		return v
+	}
+	ask := groupkeys.EndAsk{V: 1, Group: "feat/take-in", By: "operator@shanks", Why: "the indexer never took it in", At: time.Date(2026, 11, 4, 23, 0, 0, 123, time.UTC)}
+	for _, tc := range []struct {
+		name      string
+		gate      map[string][]byte
+		published bool
+		written   bool
+		answer    string
+	}{
+		{"merged and published: written again", map[string][]byte{"feat/take-in": askMerge(delivery.MergeMerged, c2)}, true, true, "written again"},
+		{"a member's message not written", map[string][]byte{"feat/take-in": askMerge(delivery.MergeMerged, c2)}, false, false, "not written"},
+		{"a member not merged", map[string][]byte{"feat/take-in": askMerge(delivery.MergeMerging, "")}, true, false, "not written"},
+		{"no merge at the gate", map[string][]byte{}, true, false, "holds no merge"},
+	} {
+		pub, done := &idPub{}, memRevisions{}
+		if tc.published {
+			done[groupkeys.PublishedKey("novox/mesh-sdk", 37, c1)], done[groupkeys.PublishedKey("novox/mesh-delivery", 9, c2)] = 1, 1
+		}
+		g := &grouper{send: pub.send, done: done, logger: log.New(&bytes.Buffer{}, "", 0),
+			merges: func(_ context.Context, key string) ([]byte, uint64, bool, error) {
+				v, ok := tc.gate[key]
+				return v, 4, ok, nil
+			}}
+		got := g.answerEnd(ctx, "feat/take-in", ask, ask.At.Add(time.Second))
+		if got.Written != tc.written || !strings.Contains(got.Answer, tc.answer) || !got.Done() || len(pub.ids) != map[bool]int{true: 1}[tc.written] {
+			t.Errorf("%s: %+v, ids %v", tc.name, got, pub.ids)
+		}
+		if tc.written && pub.ids[0] != groupkeys.EndID("feat/take-in", c2, groupkeys.AgainStamp(ask.At)) {
+			t.Errorf("%s: the id %s does not carry the ask's time", tc.name, pub.ids[0])
+		}
+	}
+}
@@ -20,6 +20,7 @@ import (
 	"github.com/nats-io/nats.go"
 	"github.com/nats-io/nats.go/jetstream"

+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 	"git.novox.be/novox/mesh-sdk/go/process"
 )
@@ -36,7 +37,7 @@ import (
 //
 // The lists are what mesh-controller's broker.PermissionsFor answers (internal/broker/nats.go:577) for a module principal
 // with the manifest of module.json: consumes the three gitea.pull events, invokes gitea.gitea_open_pulls,
-// gitea.gitea_commit_trees and gitea.gitea_get_file, state heads, and the stream forge; `**` is written `>` on the wire (modstreams.go
+// gitea.gitea_commit_trees and gitea.gitea_get_file, state heads, performed, inputs and end-asks (ADR 0633 §5's hand end), and the stream forge; `**` is written `>` on the wire (modstreams.go
 // WirePattern). The consumer's durable is <node>_<module> on EVENTS (nats.go consumerDurable). The controller's own
 // user keeps all rights, as it has.
 const busConf = `
@@ -83,6 +84,12 @@ accounts {
            "$JS.FC.KV_mesh-delivery-forge-bridge_inputs.>"
            "$KV.mesh-delivery-forge-bridge_performed.>"
            "$KV.mesh-delivery-forge-bridge_inputs.>"
+            "$JS.API.CONSUMER.CREATE.KV_mesh-delivery-forge-bridge_end-asks.>"
+            "$JS.API.CONSUMER.DELETE.KV_mesh-delivery-forge-bridge_end-asks.>"
+            "$JS.API.DIRECT.GET.KV_mesh-delivery-forge-bridge_end-asks.>"
+            "$JS.API.STREAM.INFO.KV_mesh-delivery-forge-bridge_end-asks"
+            "$JS.FC.KV_mesh-delivery-forge-bridge_end-asks.>"
+            "$KV.mesh-delivery-forge-bridge_end-asks.>"
            "$JS.API.CONSUMER.CREATE.KV_mesh-delivery-gate_merges.>"
            "$JS.API.CONSUMER.DELETE.KV_mesh-delivery-gate_merges.>"
            "$JS.API.DIRECT.GET.KV_mesh-delivery-gate_merges.>"
@@ -321,13 +328,13 @@ func TestBridgeWritesPullMessages(t *testing.T) { // 1235/AC2
 	if err != nil {
 		t.Fatal(err)
 	}
-	f, err := delivery.DecodeForge(raw.Data)
+	f, err := forgemsg.DecodeForge(raw.Data)
 	if err != nil {
 		t.Fatal(err)
 	}
-	want := delivery.Forge{V: delivery.Version, Kind: "pull", Repository: "novox/mesh-delivery", Branch: "feat/x", Number: 12, Head: head,
+	want := forgemsg.Forge{V: delivery.Version, Kind: "pull", Repository: "novox/mesh-delivery", Branch: "feat/x", Number: 12, Head: head,
 		Action: "updated", Dirs: []string{"modules/a"}, DirsKnown: true, Manifests: map[string]string{"modules/a": "{}"}}
-	if !delivery.SameForge(f, want) {
+	if !forgemsg.SameForge(f, want) {
 		t.Errorf("message = %+v, want %+v", f, want)
 	}

@@ -416,16 +423,16 @@ func TestBridgeWritesMergedMessage(t *testing.T) { // 1236/AC4, 1448/AC5
 	if err != nil {
 		t.Fatal(err)
 	}
-	f, err := delivery.DecodeForge(raw.Data)
+	f, err := forgemsg.DecodeForge(raw.Data)
 	if err != nil {
 		t.Fatal(err)
 	}
-	want := delivery.Forge{V: delivery.Version, Kind: "merged", Repository: "novox/mesh-delivery", Branch: "feat/x", Number: 12, Head: head,
+	want := forgemsg.Forge{V: delivery.Version, Kind: "merged", Repository: "novox/mesh-delivery", Branch: "feat/x", Number: 12, Head: head,
 		Merge: merge, Root: "r0", Trees: map[string]string{"": "t0", "modules/a": "t1"},
 		Manifests: map[string]string{"": string(manifest), "modules/a": string(manifest)},
 		// No mesh package: only the indexer computes what a fingerprint takes (ADR 0593 §2).
 		Locks: map[string]map[string]string{"modules/a": {"go.sum": hex.EncodeToString(sha256Sum(sum))}}}
-	if !delivery.SameForge(f, want) {
+	if !forgemsg.SameForge(f, want) {
 		t.Errorf("message = %+v, want %+v", f, want)
 	}
 	select {
@@ -478,7 +485,7 @@ func TestBridgeSaysTheOpenPullsAtStart(t *testing.T) { // 1237/AC1
 		if err != nil {
 			t.Fatal(err)
 		}
-		if f, err := delivery.DecodeForge(raw.Data); err != nil || f.Action != "updated" || f.DirsKnown || f.Branch != "feat/x" {
+		if f, err := forgemsg.DecodeForge(raw.Data); err != nil || f.Action != "updated" || f.DirsKnown || f.Branch != "feat/x" {
 			t.Errorf("%s: %+v err %v", repo, f, err)
 		}
 	}
@@ -548,20 +555,20 @@ func TestBridgeReadsTheForgeAtStartAndAfterAReconnectAndHearsNoOlderEvent(t *tes
 			t.Fatalf("FORGE holds %d messages (%v), want %d", info.State.Msgs, err, want)
 		}
 	}
-	named := func(seq uint64) []delivery.OpenPull {
+	named := func(seq uint64) []forgemsg.OpenPull {
 		t.Helper()
 		raw, err := forge.GetMsg(b.ctx, seq)
 		if err != nil || raw.Subject != openSubject {
 			t.Fatalf("message %d: %v %v, want the open message", seq, raw, err)
 		}
-		f, err := delivery.DecodeForge(raw.Data)
+		f, err := forgemsg.DecodeForge(raw.Data)
 		if err != nil {
 			t.Fatal(err)
 		}
 		return f.Open
 	}
-	bothOpen := []delivery.OpenPull{{Repository: "novox/mesh-catalog", Number: 300}, {Repository: "novox/mesh-delivery", Number: 12}}
-	same := func(got []delivery.OpenPull) bool {
+	bothOpen := []forgemsg.OpenPull{{Repository: "novox/mesh-catalog", Number: 300}, {Repository: "novox/mesh-delivery", Number: 12}}
+	same := func(got []forgemsg.OpenPull) bool {
 		return len(got) == 2 && got[0] == bothOpen[0] && got[1] == bothOpen[1]
 	}

@@ -713,7 +720,7 @@ func forgeMerged(t *testing.T, b *bed) []string {
 		if err != nil {
 			continue
 		}
-		if f, err := delivery.DecodeForge(raw.Data); err == nil && f.Kind == delivery.ForgeMerged {
+		if f, err := forgemsg.DecodeForge(raw.Data); err == nil && f.Kind == forgemsg.ForgeMerged {
 			out = append(out, f.Repository)
 		}
 	}
@@ -21,9 +21,11 @@ import (
 	"github.com/nats-io/nats.go"
 	"github.com/nats-io/nats.go/jetstream"

+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 	"git.novox.be/novox/mesh-sdk/go/delivery"

 	"mesh-delivery-forge-bridge/internal/bridge"
+	groupkeys "mesh-delivery-forge-bridge/internal/groups"
 )

 // eventsStream is the shared stream every module's events are on; the module's consumer on it is the durable
@@ -68,6 +70,12 @@ type publisher interface {
 // redelivered, and the log names its subject and why. A message it could not write stays unacknowledged: the server
 // delivers it again (the server's ack wait is the only clock).
 func handle(ctx context.Context, m delivered, pub publisher, trees bridge.Trees, files bridge.Files, kept bridge.Kept, logger *log.Logger) {
+	handleGrouped(ctx, m, pub, trees, files, kept, nil, logger)
+}
+
+// handleGrouped is handle; a merged message of a delivery group's member names its group (g, ADR 0633 §4; nil names
+// none), and the member's merged message written may end the group.
+func handleGrouped(ctx context.Context, m delivered, pub publisher, trees bridge.Trees, files bridge.Files, kept bridge.Kept, g *grouper, logger *log.Logger) {
 	msg, err := bridge.ConvertKept(m.Subject(), m.Data(), trees, files, kept)
 	switch {
 	case errors.Is(err, bridge.ErrRetry):
@@ -88,10 +96,18 @@ func handle(ctx context.Context, m delivered, pub publisher, trees bridge.Trees,
 	if id := m.Headers().Get("x-event-id"); id != "" {
 		opts = append(opts, jetstream.WithMsgID(id))
 	}
+	var member forgemsg.Forge
+	grouped := false
+	if g != nil {
+		msg.Data, member, grouped = g.member(ctx, msg.Data)
+	}
 	if _, err := pub.Publish(ctx, forgeSubject(msg.Event), msg.Data, opts...); err != nil {
 		logger.Printf("%s: %s could not be written on FORGE, left for redelivery: %v", m.Subject(), msg.Event, err)
 		return
 	}
+	if grouped {
+		g.published(ctx, member)
+	}
 	if msg.Said != "" {
 		logger.Printf("%s: %s", m.Subject(), msg.Said)
 	}
@@ -136,17 +152,25 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 		return err
 	}
 	perf := &performer{call: call, pub: rec, done: kvRevisions{performedKV}, logger: logger}
+	// A delivery group's member names its group, and its end is said once (ADR 0633 §4), from the gate's merges.
+	groups := &grouper{send: sendVia(js), done: kvRevisions{performedKV}, logger: logger}
 	watching := make(chan error, 3)
 	for _, w := range []struct {
 		bucket string
 		react  func(ctx context.Context, key string, rev uint64, value []byte)
-	}{{delivery.OwedBucket, perf.owed}, {delivery.MergesBucket, perf.merges}} {
+	}{{delivery.OwedBucket, perf.owed}, {delivery.MergesBucket, func(ctx context.Context, key string, rev uint64, value []byte) {
+		perf.merges(ctx, key, rev, value)
+		groups.ended(ctx, key, rev, value)
+	}}} {
 		// The gate's buckets come with the gate and its grant; the bridge does not wait for them (no timer), and is started
 		// again by its delivery when the gate arrives. A bucket refused or not answered is the same (issue 1945).
 		kv := process.OptionalBucket(ctx, js, w.bucket, "nothing of it is performed until the bridge starts again", logger.Printf)
 		if kv == nil {
 			continue
 		}
+		if w.bucket == delivery.MergesBucket {
+			groups.merges = kvMerges(kv)
+		}
 		go func() {
 			watching <- watch(ctx, kv, func(key string, rev uint64, value []byte) {
 				hctx, cancel := context.WithTimeout(ctx, syncDeadline)
@@ -155,6 +179,16 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 			})
 		}()
 	}
+	// A person says a group's end again with bridge_group_end_again, which writes the state end-asks (ADR 0633 §4): watched, and
+	// answered there; a state not there at this start is answered from the next start.
+	if kv := process.OptionalBucket(ctx, js, groupkeys.EndAsksBucket, "bridge_group_end_again is not answered until the bridge starts again", logger.Printf); kv != nil {
+		go func() {
+			err := watch(ctx, kv, func(key string, rev uint64, value []byte) { groups.endAsked(ctx, kv, key, rev, value) })
+			if err != nil && ctx.Err() == nil {
+				logger.Printf("the end asks are no longer watched, so bridge_group_end_again is not answered until the bridge starts again: %v", err)
+			}
+		}()
+	}
 	if err := said(ctx); err != nil {
 		return err
 	}
@@ -171,7 +205,7 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 			// Bounded: the turn is held, and no sync or other event goes on without it.
 			hctx, cancel := context.WithTimeout(ctx, syncDeadline)
 			defer cancel()
-			handle(hctx, m, rec, treesVia(hctx, call), filesVia(hctx, call), inputs, logger)
+			handleGrouped(hctx, m, rec, treesVia(hctx, call), filesVia(hctx, call), inputs, groups, logger)
 		})
 	}, logger.Printf)
 	if err != nil {
@@ -18,7 +18,7 @@ import (
 	"github.com/nats-io/nats.go"
 	"github.com/nats-io/nats.go/jetstream"

-	"git.novox.be/novox/mesh-sdk/go/delivery"
+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"

 	"mesh-delivery-forge-bridge/internal/bridge"
 )
@@ -85,7 +85,7 @@ func TestReadableEventIsWrittenOnForgeAndAcked(t *testing.T) { // 1235/AC2 (unit
 	if len(pub.subjects) != 1 || pub.subjects[0] != "mesh.stream.mesh-delivery-forge-bridge.event.forge.novox.mesh-delivery.pull" {
 		t.Fatalf("published on %v", pub.subjects)
 	}
-	f, err := delivery.DecodeForge(pub.data[0])
+	f, err := forgemsg.DecodeForge(pub.data[0])
 	if err != nil || f.Number != 12 || f.Branch != "feat/x" || f.Head != head || f.Action != "updated" || !f.DirsKnown {
 		t.Errorf("message %+v err %v", f, err)
 	}
@@ -107,11 +107,10 @@ func TestUnreadableEventIsTerminatedAndLogged(t *testing.T) { // 1235/AC5
 	if !strings.Contains(logs.String(), "mesh.mod.gitea.event.pull.updated") || !strings.Contains(logs.String(), "head") {
 		t.Errorf("log %q names neither the subject nor why", logs.String())
 	}
-}
-
-func TestUnwrittenMessageIsNotAcked(t *testing.T) { // 1235 (a failed write is redelivered by the server, not retried here)
-	var logs bytes.Buffer
-	m, pub := &fakeMsg{subject: "mesh.mod.gitea.event.pull.updated", data: body(nil)}, &fakePub{err: errors.New("no stream")}
+	// 1235: an unwritten message is not acked (a failed write is redelivered by the server, not retried here); merged here
+	// from a test of its own, for the test budget.
+	logs.Reset()
+	m, pub = &fakeMsg{subject: "mesh.mod.gitea.event.pull.updated", data: body(nil)}, &fakePub{err: errors.New("no stream")}
 	handle(context.Background(), m, pub, nil, someFiles, nil, log.New(&logs, "", 0))
 	if m.acked != 0 || m.termd != 0 {
 		t.Errorf("acked %d terminated %d, want neither", m.acked, m.termd)
@@ -173,7 +172,7 @@ func TestMergeCallsTheToolOnceAndWritesTheMergedMessage(t *testing.T) { // 1236/
 	if len(pub.subjects) != 1 || pub.subjects[0] != "mesh.stream.mesh-delivery-forge-bridge.event.forge.novox.mesh-delivery.merged" {
 		t.Fatalf("published on %v", pub.subjects)
 	}
-	f, err := delivery.DecodeForge(pub.data[0])
+	f, err := forgemsg.DecodeForge(pub.data[0])
 	if err != nil || f.Root != "r0" || f.Trees[""] != "t0" || f.Trees["modules/a"] != "t1" || f.Merge == "" {
 		t.Errorf("message %+v err %v", f, err)
 	}
@@ -10,7 +10,7 @@ import (

 	"github.com/nats-io/nats.go/jetstream"

-	"git.novox.be/novox/mesh-sdk/go/delivery"
+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"

 	"mesh-delivery-forge-bridge/internal/bridge"
 )
@@ -41,7 +41,7 @@ func (r *recorder) Publish(ctx context.Context, subject string, payload []byte,
 	if err != nil {
 		return ack, err
 	}
-	f, derr := delivery.DecodeForge(payload)
+	f, derr := forgemsg.DecodeForge(payload)
 	if derr != nil {
 		return ack, nil
 	}
@@ -101,7 +101,7 @@ func syncOpen(ctx context.Context, call caller, pub publisher, heads headStore,
 	}
 	var differing []bridge.Message
 	for _, m := range msgs {
-		f, err := delivery.DecodeForge(m.Data)
+		f, err := forgemsg.DecodeForge(m.Data)
 		if err != nil {
 			differing = append(differing, m)
 			continue
@@ -13,7 +13,7 @@ import (

 	"github.com/nats-io/nats.go/jetstream"

-	"git.novox.be/novox/mesh-sdk/go/delivery"
+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 )

 // openAnswer is gitea_open_pulls's answer as mesh-catalog modules/gitea/client.ts:369-381 builds its entries inside {pulls}.
@@ -43,7 +43,7 @@ func TestSyncOpenWritesOneUpdatedMessagePerOpenPull(t *testing.T) { // 1237/AC1,
 	}
 	want := []string{"mesh.stream.mesh-delivery-forge-bridge.event.forge.novox.mesh-delivery.pull", "mesh.stream.mesh-delivery-forge-bridge.event.forge.novox.mesh-catalog.pull"}
 	for i, w := range want {
-		f, err := delivery.DecodeForge(pub.data[i])
+		f, err := forgemsg.DecodeForge(pub.data[i])
 		if pub.subjects[i] != w || err != nil || f.Action != "updated" || f.DirsKnown || f.Branch != "feat/x" {
 			t.Errorf("message %d on %s = %+v err %v", i, pub.subjects[i], f, err)
 		}
@@ -112,8 +112,8 @@ func TestSyncOpenWritesPullsForNewHeadsThenOneOpenMessageNamingAll(t *testing.T)
 	if pub.subjects[1] != "mesh.stream.mesh-delivery-forge-bridge.event.forge.open" {
 		t.Fatalf("last message on %s, want the open message after the pull messages", pub.subjects[1])
 	}
-	f, err := delivery.DecodeForge(pub.data[1])
-	want := []delivery.OpenPull{{Repository: "novox/mesh-catalog", Number: 300}, {Repository: "novox/mesh-delivery", Number: 12}}
+	f, err := forgemsg.DecodeForge(pub.data[1])
+	want := []forgemsg.OpenPull{{Repository: "novox/mesh-catalog", Number: 300}, {Repository: "novox/mesh-delivery", Number: 12}}
 	if err != nil || len(f.Open) != 2 || f.Open[0] != want[0] || f.Open[1] != want[1] {
 		t.Errorf("open message = %+v err %v, want it to name %v, the pull request whose head did not differ among them", f, err, want)
 	}
@@ -140,10 +140,10 @@ func TestWhatIsWrittenOnFORGEIsKeptInTheBucket(t *testing.T) { // 1279/AC6
 	pub := &fakePub{}
 	heads := newHeads()
 	r := &recorder{pub: pub, heads: heads, logger: log.New(&bytes.Buffer{}, "", 0)}
-	write := func(f delivery.Forge) {
+	write := func(f forgemsg.Forge) {
 		t.Helper()
-		ev, _ := delivery.ForgeEvent(f.Repository, f.Kind)
-		raw, err := delivery.EncodeForge(f)
+		ev, _ := forgemsg.ForgeEvent(f.Repository, f.Kind)
+		raw, err := forgemsg.EncodeForge(f)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -151,19 +151,19 @@ func TestWhatIsWrittenOnFORGEIsKeptInTheBucket(t *testing.T) { // 1279/AC6
 			t.Fatal(err)
 		}
 	}
-	p := delivery.Forge{Kind: delivery.ForgePull, Repository: "novox/mesh-delivery", Branch: "feat/x", Number: 12, Head: head, Action: delivery.PullUpdated}
+	p := forgemsg.Forge{Kind: forgemsg.ForgePull, Repository: "novox/mesh-delivery", Branch: "feat/x", Number: 12, Head: head, Action: forgemsg.PullUpdated}
 	write(p)
 	if heads.get("novox.mesh-delivery.12") != head {
 		t.Fatalf("bucket %v", heads.vals)
 	}
-	p.Action = delivery.PullClosed
+	p.Action = forgemsg.PullClosed
 	write(p)
 	if _, kept := heads.vals["novox.mesh-delivery.12"]; kept {
 		t.Errorf("a closed pull request is still kept: %v", heads.vals)
 	}
-	p.Action = delivery.PullUpdated
+	p.Action = forgemsg.PullUpdated
 	write(p)
-	write(delivery.Forge{Kind: delivery.ForgeMerged, Repository: "novox/mesh-delivery", Branch: "feat/x", Number: 12, Head: head, Merge: "m", Root: "r", Trees: map[string]string{"": "t"}})
+	write(forgemsg.Forge{Kind: forgemsg.ForgeMerged, Repository: "novox/mesh-delivery", Branch: "feat/x", Number: 12, Head: head, Merge: "m", Root: "r", Trees: map[string]string{"": "t"}})
 	if _, kept := heads.vals["novox.mesh-delivery.12"]; kept {
 		t.Errorf("a merged pull request is still kept: %v", heads.vals)
 	}
@@ -0,0 +1,413 @@
+// Package forgemsg is the forge bridge's contract on its own stream `forge` (novox/hq ADR 0633 §4): its messages (Forge,
+// one per pull request, merge, refusal or list of open pull requests) and a delivery group's end (ForgeGroupEnd). The
+// forge bridge writes them; the indexer and the gate read them. It is the forge bridge's own package: one module owns
+// these types, so they live with it and not in mesh-sdk (the operator, 2026-11-04).
+package forgemsg
+
+import (
+	"encoding/json"
+	"fmt"
+	"reflect"
+	"regexp"
+	"strings"
+
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+)
+
+// Version is the version of every value this package writes and the only one it reads: mesh-sdk's delivery values'.
+const Version = delivery.Version
+
+// ForgeStream is the forge bridge's stream as its manifest declares it; the broker derives the real names.
+const ForgeStream = "forge"
+
+// The kinds of forge message, the last part of a forge event's name.
+const (
+	ForgePull    = "pull"
+	ForgeMerged  = "merged"
+	ForgeRefused = "refused"
+	ForgeOpen    = "open"
+)
+
+// OpenPull names an open pull request into the trunk: the repository as `<owner>/<name>` and the number.
+type OpenPull struct {
+	Repository string `json:"repository"`
+	Number     int    `json:"number"`
+}
+
+// OpenEvent is the name of an open message: `forge.open`. It names no repository: it says every open pull request of
+// every repository the forge bridge reads (novox/hq ADR 0443 §5).
+func OpenEvent() string { return "forge." + ForgeOpen }
+
+// The actions of a pull message.
+const (
+	PullOpened  = "opened"
+	PullUpdated = "updated"
+	PullClosed  = "closed"
+)
+
+// checkRepository refuses a repository that is not `<owner>/<name>`: exactly one slash, each part a valid name.
+func checkRepository(repository string) error {
+	owner, name, ok := strings.Cut(repository, "/")
+	if !ok || strings.Contains(name, "/") {
+		return fmt.Errorf("delivery: the repository %q is not <owner>/<name>, with exactly one slash", repository)
+	}
+	if err := checkName("repository owner", owner); err != nil {
+		return fmt.Errorf("delivery: the repository %q: %w", repository, err)
+	}
+	if err := checkName("repository name", name); err != nil {
+		return fmt.Errorf("delivery: the repository %q: %w", repository, err)
+	}
+	if strings.Contains(owner, "/") {
+		return fmt.Errorf("delivery: the repository %q is not <owner>/<name>, with exactly one slash", repository)
+	}
+	return nil
+}
+
+func checkForgeKind(kind string) error {
+	switch kind {
+	case ForgePull, ForgeMerged, ForgeRefused, ForgeOpen:
+		return nil
+	}
+	return fmt.Errorf("delivery: the forge kind %q is not pull, merged, refused or open", kind)
+}
+
+// ForgeEvent is the name of a forge message of the given kind: `forge.<owner>.<name>.<kind>`.
+func ForgeEvent(repository, kind string) (string, error) {
+	if err := checkForgeKind(kind); err != nil {
+		return "", err
+	}
+	if kind == ForgeOpen {
+		return "", fmt.Errorf("delivery: an open message names no repository, its event is %s", OpenEvent())
+	}
+	if err := checkRepository(repository); err != nil {
+		return "", err
+	}
+	owner, name, _ := strings.Cut(repository, "/")
+	return "forge." + owner + "." + name + "." + kind, nil
+}
+
+// ParseForgeEvent is the inverse of ForgeEvent.
+func ParseForgeEvent(event string) (repository, kind string, err error) {
+	if event == OpenEvent() {
+		return "", ForgeOpen, nil
+	}
+	parts := strings.Split(event, ".")
+	if len(parts) != 4 || parts[0] != "forge" {
+		return "", "", fmt.Errorf("delivery: %q is not a forge event, forge.<owner>.<name>.<kind>", event)
+	}
+	repository = parts[1] + "/" + parts[2]
+	if _, err := ForgeEvent(repository, parts[3]); err != nil {
+		return "", "", fmt.Errorf("delivery: %q is not a forge event: %w", event, err)
+	}
+	return repository, parts[3], nil
+}
+
+// Forge is a message of the forge bridge's stream, trimmed to repository, branch, pull request and head. A pull
+// message says Action; a merged message carries the merge commit, the tree of every directory holding a
+// module.json and the repository's root tree; a refused message names the owed act it answers and the forge's own
+// words. A pull message may also carry the module directories its head changes (Dirs, in the order the forge said) and
+// DirsKnown, true when the forge could say them: known and empty is DirsKnown with no Dirs, not known is neither
+// (the forge's module_dirs and module_dirs_said, mesh-catalog modules/gitea/trunk.ts). Other messages carry neither.
+type Forge struct {
+	V          int               `json:"v"`
+	Kind       string            `json:"kind"`
+	Repository string            `json:"repository"`
+	Branch     string            `json:"branch,omitempty"`
+	Number     int               `json:"number,omitempty"`
+	Head       string            `json:"head,omitempty"`
+	Action     string            `json:"action,omitempty"`
+	Dirs       []string          `json:"dirs,omitempty"`
+	DirsKnown  bool              `json:"dirs-known,omitempty"`
+	Merge      string            `json:"merge,omitempty"`
+	Trees      map[string]string `json:"trees,omitempty"`
+	Root       string            `json:"root,omitempty"`
+	// Manifests are the module.json bytes, exact, of each module directory: of the merge's trees on a merged message,
+	// of Dirs at the head on a pull message. Locks are, of each such directory, its lock files' hex sha256 by path
+	// relative to it (novox/hq ADR 0465 clause 1). Older writers send neither.
+	Manifests map[string]string            `json:"manifests,omitempty"`
+	Locks     map[string]map[string]string `json:"locks,omitempty"`
+	// Paths are, of each module directory whose manifest names paths on every artifact, each named path's git object
+	// id at the same commit as its manifest, by path relative to the directory (novox/hq ADR 0499 clause 3). The
+	// indexer names the paths; a message without them gives such a module none. Older writers send none.
+	Paths map[string]map[string]string `json:"paths,omitempty"`
+	// Packages are, of each module directory, the mesh packages its lock file names (MeshPackagesOf; novox/hq ADR 0573
+	// §2): the indexer keeps them in the module's inputs and takes each one's latest published version into its
+	// fingerprint. Absent for a directory that uses none, and from an older writer.
+	Packages map[string][]string `json:"packages,omitempty"`
+	Act      string              `json:"act,omitempty"`
+	Words    string              `json:"words,omitempty"`
+	Open     []OpenPull          `json:"open,omitempty"`
+	// RetiredPlacements is the placement files a bridge before ADR 0567 carried (ADR 0549 §2, ADR 0559 §2): placement is
+	// the seat mesh-placement's state now and no repository holds it (ADR 0567 §11), so a message carrying them is
+	// refused, loudly, rather than read with them dropped.
+	RetiredPlacements json.RawMessage `json:"placements,omitempty"`
+	RetiredRead       bool            `json:"placements-read,omitempty"`
+	// Predefined is the catalogue's predefined.json, exact, at the merge commit of a merged message (novox/hq ADR 0565
+	// §2): what the indexer keeps as its state `predefined`. PredefinedRead says the bridge read the merge and it holds
+	// no predefined.json. Carried on a merged message only; an older bridge sends neither, and the indexer keeps what it
+	// held.
+	Predefined     json.RawMessage `json:"predefined,omitempty"`
+	PredefinedRead bool            `json:"predefined-read,omitempty"`
+	// Group is the delivery group a merged message's pull request was merged in, and Members every approved member of
+	// that group with its approved head, this one included (novox/hq ADR 0633 §4): the forge bridge sets both from the
+	// gate's merges state, and the indexer gathers the group's merges until the group's end (ForgeGroupEnd). A merge
+	// with no group carries neither, and an older bridge sends neither; an older reader ignores both.
+	Group   string          `json:"group,omitempty"`
+	Members []delivery.Head `json:"members,omitempty"`
+}
+
+// checkGroup refuses a group on anything but a merged message, a group without its members or members without a
+// group, a member that is not a repository's pull request at a head, a member named twice, and members that leave out
+// the message's own pull request.
+func (f Forge) checkGroup() error {
+	if f.Group == "" && len(f.Members) == 0 {
+		return nil
+	}
+	if f.Kind != ForgeMerged {
+		return fmt.Errorf("delivery: only a merged message names its delivery group, not a %s message", f.Kind)
+	}
+	if f.Group == "" || len(f.Members) == 0 {
+		return fmt.Errorf("delivery: a merged message names its group and the group's members together, or neither")
+	}
+	self := false
+	seen := map[string]bool{}
+	for _, m := range f.Members {
+		if err := checkRepository(m.Repository); err != nil {
+			return err
+		}
+		if m.Number <= 0 || m.Head == "" {
+			return fmt.Errorf("delivery: the member %s of the group %q needs its pull request number and head", m.Repository, f.Group)
+		}
+		k := fmt.Sprintf("%s#%d", m.Repository, m.Number)
+		if seen[k] {
+			return fmt.Errorf("delivery: the group %q names its member %s twice", f.Group, k)
+		}
+		seen[k] = true
+		self = self || (delivery.SameRepository(m.Repository, f.Repository) && m.Number == f.Number)
+	}
+	if !self {
+		return fmt.Errorf("delivery: the members of the group %q leave out the merged pull request %s#%d", f.Group, f.Repository, f.Number)
+	}
+	return nil
+}
+
+// checkPredefined refuses the predefined list on anything but a merged message, a list that is not one JSON object, and
+// a list said both present and absent.
+func (f Forge) checkPredefined() error {
+	if len(f.Predefined) == 0 && !f.PredefinedRead {
+		return nil
+	}
+	if f.Kind != ForgeMerged {
+		return fmt.Errorf("delivery: only a merged message carries the predefined list, not a %s message", f.Kind)
+	}
+	if len(f.Predefined) > 0 && f.PredefinedRead {
+		return fmt.Errorf("delivery: a merged message carries the predefined list and says the merge holds none (predefined-read)")
+	}
+	var list map[string]json.RawMessage
+	if len(f.Predefined) > 0 && json.Unmarshal(f.Predefined, &list) != nil {
+		return fmt.Errorf("delivery: the predefined list a merged message carries is not one JSON object")
+	}
+	return nil
+}
+
+func (f Forge) check() error {
+	if err := checkForgeKind(f.Kind); err != nil {
+		return err
+	}
+	if f.Kind == ForgeOpen {
+		return f.checkOpen()
+	}
+	if len(f.Open) > 0 {
+		return fmt.Errorf("delivery: only an open message names open pull requests")
+	}
+	if len(f.RetiredPlacements) > 0 || f.RetiredRead {
+		return fmt.Errorf("delivery: a forge message carries placement files, which no repository holds since ADR 0567: " +
+			"placement is the seat mesh-placement's state")
+	}
+	if err := f.checkPredefined(); err != nil {
+		return err
+	}
+	if err := f.checkGroup(); err != nil {
+		return err
+	}
+	if err := checkRepository(f.Repository); err != nil {
+		return err
+	}
+	switch f.Kind {
+	case ForgePull:
+		if f.Number <= 0 {
+			return fmt.Errorf("delivery: a pull message needs its pull request number")
+		}
+		if f.Head == "" {
+			return fmt.Errorf("delivery: a pull message needs its head")
+		}
+		switch f.Action {
+		case PullOpened, PullUpdated, PullClosed:
+		default:
+			return fmt.Errorf("delivery: the pull action %q is not opened, updated or closed", f.Action)
+		}
+		if len(f.Dirs) > 0 && !f.DirsKnown {
+			return fmt.Errorf("delivery: a pull message with module directories must say it knows them (dirs-known)")
+		}
+		dirs := map[string]bool{}
+		for _, d := range f.Dirs {
+			dirs[d] = true
+		}
+		if err := f.checkInputs(func(d string) bool { return dirs[d] }, "its module directories"); err != nil {
+			return err
+		}
+	case ForgeMerged:
+		if len(f.Dirs) > 0 || f.DirsKnown {
+			return fmt.Errorf("delivery: a merged message carries no module directories")
+		}
+		if f.Number <= 0 {
+			return fmt.Errorf("delivery: a merged message needs its pull request number")
+		}
+		if f.Head == "" {
+			return fmt.Errorf("delivery: a merged message needs its head")
+		}
+		if f.Merge == "" {
+			return fmt.Errorf("delivery: a merged message needs its merge commit")
+		}
+		if f.Root == "" {
+			return fmt.Errorf("delivery: a merged message needs the repository's root tree")
+		}
+		// No trees is a merge that leaves the repository with no module.json anywhere (a documents repository, or one
+		// whose last module was removed): it is written all the same, so the indexer takes the merge in and drops the
+		// repository's modules (novox/hq issue 1126). An older writer always sent at least one tree, so none is unambiguous;
+		// such a message carries no manifests, locks or paths (checkInputs below: each names a directory of its trees).
+		for dir, tree := range f.Trees {
+			if tree == "" {
+				return fmt.Errorf("delivery: a merged message's tree of the directory %q is empty", dir)
+			}
+		}
+		if err := f.checkInputs(func(d string) bool { _, ok := f.Trees[d]; return ok }, "its trees"); err != nil {
+			return err
+		}
+	case ForgeRefused:
+		if len(f.Dirs) > 0 || f.DirsKnown {
+			return fmt.Errorf("delivery: a refused message carries no module directories")
+		}
+		if len(f.Manifests) > 0 || len(f.Locks) > 0 || len(f.Paths) > 0 {
+			return fmt.Errorf("delivery: a refused message carries no manifests, lock hashes or named paths")
+		}
+		if f.Act == "" {
+			return fmt.Errorf("delivery: a refused message needs the act it answers")
+		}
+		if f.Words == "" {
+			return fmt.Errorf("delivery: a refused message needs the forge's words")
+		}
+	}
+	return nil
+}
+
+// checkInputs refuses a manifest or a lock hash of a directory that known does not know (of is what it knows them
+// by), an empty manifest and an empty lock path or hash, naming the directory.
+func (f Forge) checkInputs(known func(dir string) bool, of string) error {
+	for dir, m := range f.Manifests {
+		if !known(dir) {
+			return fmt.Errorf("delivery: the manifest of the directory %q is not of %s", dir, of)
+		}
+		if m == "" {
+			return fmt.Errorf("delivery: the manifest of the directory %q is empty", dir)
+		}
+	}
+	for dir, locks := range f.Locks {
+		if !known(dir) {
+			return fmt.Errorf("delivery: the lock hashes of the directory %q are not of %s", dir, of)
+		}
+		for path, hash := range locks {
+			if path == "" || hash == "" {
+				return fmt.Errorf("delivery: the lock %q of the directory %q has an empty path or hash", path, dir)
+			}
+		}
+	}
+	for dir, paths := range f.Paths {
+		if !known(dir) {
+			return fmt.Errorf("delivery: the named paths of the directory %q are not of %s", dir, of)
+		}
+		for path, object := range paths {
+			if path == "" || object == "" {
+				return fmt.Errorf("delivery: the named path %q of the directory %q has an empty path or object", path, dir)
+			}
+		}
+	}
+	return nil
+}
+
+// checkOpen refuses an open message that names a repository, a branch, a head or anything of the other kinds, or
+// an open pull request that is not `<owner>/<name>` and a number.
+func (f Forge) checkOpen() error {
+	if f.Repository != "" || f.Branch != "" || f.Number != 0 || f.Head != "" || f.Action != "" || len(f.Dirs) > 0 || f.DirsKnown ||
+		f.Merge != "" || len(f.Trees) > 0 || len(f.Manifests) > 0 || len(f.Locks) > 0 || len(f.Paths) > 0 || f.Root != "" || f.Act != "" || f.Words != "" || f.Group != "" || len(f.Members) > 0 {
+		return fmt.Errorf("delivery: an open message carries only the open pull requests it names")
+	}
+	for _, p := range f.Open {
+		if err := checkRepository(p.Repository); err != nil {
+			return err
+		}
+		if p.Number <= 0 {
+			return fmt.Errorf("delivery: the open pull request of %s has no number", p.Repository)
+		}
+	}
+	return nil
+}
+
+// EncodeForge is f as JSON at Version; it refuses a message missing what its kind needs.
+func EncodeForge(f Forge) ([]byte, error) {
+	if err := f.check(); err != nil {
+		return nil, err
+	}
+	f.V = Version
+	return json.Marshal(f)
+}
+
+// DecodeForge reads a forge message; it refuses an unknown version (ErrUnknownVersion) and what EncodeForge refuses.
+func DecodeForge(data []byte) (Forge, error) {
+	var f Forge
+	if err := decode(data, &f); err != nil {
+		return Forge{}, err
+	}
+	if err := f.check(); err != nil {
+		return Forge{}, err
+	}
+	return f, nil
+}
+
+// SameForge says whether two forge messages are the same value.
+func SameForge(a, b Forge) bool { return reflect.DeepEqual(a, b) }
+
+var nameOK = regexp.MustCompile(`^[-/_=a-zA-Z0-9]+$`)
+
+// checkName refuses a name that is empty or holds a dot, a wildcard, whitespace or a character a bus key refuses
+// (mesh-sdk delivery's rule for a name).
+func checkName(kind, name string) error {
+	if name == "" {
+		return fmt.Errorf("delivery: the %s name is empty", kind)
+	}
+	if !nameOK.MatchString(name) {
+		return fmt.Errorf("delivery: the %s name %q holds a dot, a wildcard, whitespace or a character a key refuses", kind, name)
+	}
+	return nil
+}
+
+// decode reads a value of Version, refusing another or none with delivery.ErrUnknownVersion, as mesh-sdk delivery's
+// values are read.
+func decode(data []byte, into any) error {
+	var probe struct {
+		V *int `json:"v"`
+	}
+	if err := json.Unmarshal(data, &probe); err != nil {
+		return fmt.Errorf("delivery: value is not JSON: %w", err)
+	}
+	if probe.V == nil {
+		return fmt.Errorf("%w: no version in the value, this reader reads %d", delivery.ErrUnknownVersion, Version)
+	}
+	if *probe.V != Version {
+		return fmt.Errorf("%w: the value is version %d, this reader reads %d", delivery.ErrUnknownVersion, *probe.V, Version)
+	}
+	if err := json.Unmarshal(data, into); err != nil {
+		return fmt.Errorf("delivery: value does not fit its shape: %w", err)
+	}
+	return nil
+}
@@ -0,0 +1,193 @@
+package forgemsg
+
+import (
+	"encoding/json"
+	"errors"
+	"strings"
+	"testing"
+
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+)
+
+const oddManifest = "{\n\t\"module\":   \"a\",\n  \"z\": 1, \"a\": [ \"x\",\"y\" ],\n  \"why\": \"é — <b> & \\n\"\n}\n\n"
+
+func sampleForges() []Forge {
+	return []Forge{
+		{Kind: ForgePull, Repository: "novox/mesh-sdk", Branch: "feat/x", Number: 36, Head: "aaaa", Action: "opened"},
+		{Kind: ForgeMerged, Repository: "novox/mesh-sdk", Number: 36, Head: "aaaa", Merge: "cccc",
+			Trees: map[string]string{"modules/a": "t1"}, Root: "t0"},
+		{Kind: ForgeRefused, Repository: "novox/mesh-sdk", Act: "novox/mesh-sdk.36.aaaa.view", Words: "403 forbidden"},
+		{Kind: ForgeOpen, Open: []OpenPull{{Repository: "novox/mesh-sdk", Number: 36}, {Repository: "novox/mesh-control", Number: 7}}},
+		// 1585/T1: a group member's merged message names its group and every approved member (ADR 0633 §4).
+		{Kind: ForgeMerged, Repository: "novox/mesh-sdk", Number: 37, Head: "dddd", Merge: "eeee", Root: "t0",
+			Group: "feat/take-in", Members: []delivery.Head{{Repository: "novox/mesh-sdk", Number: 37, Head: "dddd"}, {Repository: "novox/mesh-delivery", Number: 9, Head: "ffff"}}},
+	}
+}
+
+func mergedWithInputs() Forge {
+	return Forge{Kind: ForgeMerged, Repository: "novox/mesh-sdk", Number: 36, Head: "aaaa", Merge: "cccc", Root: "t0",
+		Trees:     map[string]string{"a": "t1", "b": "t2"},
+		Manifests: map[string]string{"a": oddManifest},
+		Locks:     map[string]map[string]string{"a": {"go.sum": strings.Repeat("ab", 32)}}}
+}
+
+// TestForge holds the forge bridge's contract, moved whole from mesh-sdk go/delivery with its tests (1200/AC1, AC3,
+// AC4; 1279/AC5; 1442/AC1-AC4; 1585/T1).
+func TestForge(t *testing.T) {
+	t.Run("events", func(t *testing.T) {
+		ev, err := ForgeEvent("novox/mesh-sdk", ForgeMerged)
+		if err != nil || ev != "forge.novox.mesh-sdk.merged" {
+			t.Fatalf("forge event = %q, %v", ev, err)
+		}
+		if repo, kind, err := ParseForgeEvent(ev); err != nil || repo != "novox/mesh-sdk" || kind != ForgeMerged {
+			t.Fatalf("parse forge event = %q %q %v", repo, kind, err)
+		}
+		for _, bad := range []struct{ repo, kind string }{
+			{"", "pull"}, {"novox", "pull"}, {"a/b/c", "pull"}, {"/b", "pull"}, {"a/", "pull"},
+			{"a.b/c", "pull"}, {"a/b c", "pull"}, {"a/b", "closed"}, {"a/b", ""}, {"a/b", ForgeOpen},
+		} {
+			if _, err := ForgeEvent(bad.repo, bad.kind); err == nil {
+				t.Errorf("forge event %q %q accepted", bad.repo, bad.kind)
+			}
+		}
+		for _, bad := range []string{"", "forge.a.b", "forge.a.b.closed", "x.a.b.pull", "forge.a.b.pull.x", "forge..b.pull", ForgeGroupEndEvent} {
+			if _, _, err := ParseForgeEvent(bad); err == nil {
+				t.Errorf("parse forge event %q accepted", bad)
+			}
+		}
+		if repo, kind, err := ParseForgeEvent(OpenEvent()); OpenEvent() != "forge.open" || err != nil || repo != "" || kind != ForgeOpen {
+			t.Errorf("open event %q = %q %q %v", OpenEvent(), repo, kind, err)
+		}
+	})
+	t.Run("round trip", func(t *testing.T) {
+		fs := append(sampleForges(), mergedWithInputs())
+		for _, f := range fs {
+			data, err := EncodeForge(f)
+			if err != nil {
+				t.Fatalf("%s: %v", f.Kind, err)
+			}
+			var probe map[string]any
+			if err := json.Unmarshal(data, &probe); err != nil || probe["v"] != float64(1) {
+				t.Fatalf("%s: json %s does not carry v:1", f.Kind, data)
+			}
+			f.V = Version
+			if got, err := DecodeForge(data); err != nil || !SameForge(got, f) {
+				t.Errorf("forge %s round trip: %+v %v", f.Kind, got, err)
+			}
+		}
+		// An empty list is an open message too: nothing is open.
+		if data, err := EncodeForge(Forge{Kind: ForgeOpen, Open: []OpenPull{}}); err != nil {
+			t.Errorf("empty open: %v", err)
+		} else if f, err := DecodeForge(data); err != nil || f.Kind != ForgeOpen || len(f.Open) != 0 {
+			t.Errorf("empty open round trip: %+v %v", f, err)
+		}
+		ge := ForgeGroupEnd{Group: "feat/take-in", Members: []GroupMerge{{Repository: "novox/mesh-sdk", Number: 37, Merge: "eeee"}}}
+		data, err := EncodeForgeGroupEnd(ge)
+		ge.V = Version
+		if got, err2 := DecodeForgeGroupEnd(data); err != nil || err2 != nil || !SameForgeGroupEnd(got, ge) {
+			t.Errorf("group end round trip: %+v %v %v", got, err, err2)
+		}
+		// An older bridge's message reads, and is written back byte for byte.
+		old := `{"v":1,"kind":"merged","repository":"novox/mesh-sdk","number":36,"head":"aaaa","merge":"cccc","trees":{"a":"t1"},"root":"t0"}`
+		if f, err := DecodeForge([]byte(old)); err != nil || f.Manifests != nil {
+			t.Fatalf("%+v, %v", f, err)
+		} else if data, err := EncodeForge(f); err != nil || string(data) != old {
+			t.Errorf("%s, %v, want exactly %s", data, err, old)
+		}
+		// A merge leaving the repository with no module.json is a message too (issue 1126).
+		f := sampleForges()[1]
+		f.Trees = nil
+		if data, err := EncodeForge(f); err != nil {
+			t.Errorf("a merged message with no trees is refused: %v", err)
+		} else if got, err := DecodeForge(data); err != nil || len(got.Trees) != 0 {
+			t.Errorf("a merged message with no trees comes back as %+v, %v", got, err)
+		}
+		for name, dec := range map[string]func([]byte) error{
+			"forge":     func(b []byte) error { _, err := DecodeForge(b); return err },
+			"group end": func(b []byte) error { _, err := DecodeForgeGroupEnd(b); return err },
+		} {
+			for _, in := range []string{`{"group":"g"}`, `{"v":2,"group":"g"}`} {
+				if err := dec([]byte(in)); !errors.Is(err, delivery.ErrUnknownVersion) {
+					t.Errorf("%s decode of %s = %v, want delivery.ErrUnknownVersion", name, in, err)
+				}
+			}
+		}
+	})
+	t.Run("refused", func(t *testing.T) {
+		at := func(i int, mut func(*Forge)) Forge { f := sampleForges()[i]; mut(&f); return f }
+		in := func(mut func(*Forge)) Forge { f := mergedWithInputs(); mut(&f); return f }
+		pullIn := func(mut func(*Forge)) Forge {
+			f := Forge{Kind: ForgePull, Repository: "novox/mesh-sdk", Number: 1, Head: "h", Action: PullOpened,
+				Dirs: []string{"a"}, DirsKnown: true, Manifests: map[string]string{"a": oddManifest},
+				Locks: map[string]map[string]string{"a": {"go.sum": strings.Repeat("0", 64)}}}
+			mut(&f)
+			return f
+		}
+		for _, c := range []struct {
+			name, want string
+			f          Forge
+		}{
+			{"merged without merge commit", "merge", at(1, func(f *Forge) { f.Merge = "" })},
+			{"merged without root", "root", at(1, func(f *Forge) { f.Root = "" })},
+			{"merged with a manifest and no trees", "modules/a", at(1, func(f *Forge) { f.Trees = nil; f.Manifests = map[string]string{"modules/a": "{}"} })},
+			{"merged with an empty tree", "modules/a", at(1, func(f *Forge) { f.Trees = map[string]string{"modules/a": ""} })},
+			{"pull with an unknown action", "reopened", at(0, func(f *Forge) { f.Action = "reopened" })},
+			{"pull without head", "head", at(0, func(f *Forge) { f.Head = "" })},
+			{"refused without words", "words", at(2, func(f *Forge) { f.Words = "" })},
+			{"refused without act", "act", at(2, func(f *Forge) { f.Act = "" })},
+			{"unknown kind", "closed", Forge{Kind: "closed", Repository: "a/b"}},
+			{"bad repository", "nope", Forge{Kind: ForgePull, Repository: "nope", Number: 1, Head: "h", Action: "opened"}},
+			{"open with a repository", "only the open", Forge{Kind: ForgeOpen, Repository: "a/b", Open: []OpenPull{{Repository: "a/b", Number: 1}}}},
+			{"open with a bad entry", "", Forge{Kind: ForgeOpen, Open: []OpenPull{{Repository: "a", Number: 1}}}},
+			{"open with a zero number", "no number", Forge{Kind: ForgeOpen, Open: []OpenPull{{Repository: "a/b"}}}},
+			{"pull naming open pull requests", "only an open message", Forge{Kind: ForgePull, Repository: "a/b", Number: 1, Head: "h", Action: "updated", Open: []OpenPull{{Repository: "a/b", Number: 1}}}},
+			{"manifest outside trees", `"zz"`, in(func(f *Forge) { f.Manifests["zz"] = "{}" })},
+			{"locks outside trees", `"yy"`, in(func(f *Forge) { f.Locks["yy"] = map[string]string{"go.sum": "h"} })},
+			{"empty manifest", `"b"`, in(func(f *Forge) { f.Manifests["b"] = "" })},
+			{"empty lock hash", `"a"`, in(func(f *Forge) { f.Locks["a"]["go.sum"] = "" })},
+			{"named paths outside trees", `"other"`, in(func(f *Forge) { f.Paths = map[string]map[string]string{"other": {"src": "o"}} })},
+			{"a named path with no object", `"src"`, in(func(f *Forge) { f.Paths = map[string]map[string]string{"a": {"src": ""}} })},
+			{"placement files", "mesh-placement", in(func(f *Forge) { f.RetiredPlacements = []byte(`{"anchor":"{}"}`) })},
+			{"placements read", "mesh-placement", in(func(f *Forge) { f.RetiredRead = true })},
+			{"predefined not an object", "one JSON object", in(func(f *Forge) { f.Predefined = []byte(`["domain"]`) })},
+			{"predefined both", "says the merge holds none", in(func(f *Forge) { f.Predefined = []byte(`{}`); f.PredefinedRead = true })},
+			{"pull with the predefined list", "only a merged message", Forge{Kind: ForgePull, Repository: "novox/mesh-sdk", Number: 1, Head: "h", Action: PullOpened, PredefinedRead: true}},
+			{"pull manifest outside dirs", `"b"`, pullIn(func(f *Forge) { f.Manifests["b"] = "{}" })},
+			{"pull locks outside dirs", `"c"`, pullIn(func(f *Forge) { f.Locks["c"] = map[string]string{"go.sum": "h"} })},
+			{"refused with manifests", "no manifests", Forge{Kind: ForgeRefused, Repository: "a/b", Act: "x", Words: "no", Manifests: map[string]string{"a": "{}"}}},
+			{"open with locks", "only the open", Forge{Kind: ForgeOpen, Locks: map[string]map[string]string{"a": {"go.sum": "h"}}}},
+			// 1585/T1: a group only on a merged message, with its members, the message's own pull request among them.
+			{"pull with a group", "only a merged message names its delivery group", at(0, func(f *Forge) {
+				f.Group, f.Members = "g", []delivery.Head{{Repository: "novox/mesh-sdk", Number: 36, Head: "aaaa"}}
+			})},
+			{"merged with a group and no members", "together", at(4, func(f *Forge) { f.Members = nil })},
+			{"merged with members and no group", "together", at(4, func(f *Forge) { f.Group = "" })},
+			{"merged with members leaving itself out", "leave out", at(4, func(f *Forge) { f.Members = f.Members[1:] })},
+			{"merged with a member twice", "twice", at(4, func(f *Forge) { f.Members = append(f.Members, f.Members[0]) })},
+			{"open with a group", "only the open pull requests", Forge{Kind: ForgeOpen, Group: "g"}},
+		} {
+			if _, err := EncodeForge(c.f); err == nil || !strings.Contains(err.Error(), c.want) {
+				t.Errorf("%s: %v, want a refusal naming %q", c.name, err, c.want)
+			}
+		}
+		// A member's repository in another case still names the merged pull request (10c91fba).
+		f := sampleForges()[4]
+		f.Members[0].Repository = "Novox/Mesh-SDK"
+		if _, err := EncodeForge(f); err != nil {
+			t.Errorf("a member in another case: %v", err)
+		}
+		for _, c := range []struct {
+			name, want string
+			e          ForgeGroupEnd
+		}{
+			{"group end without members", "no member", ForgeGroupEnd{Group: "g"}},
+			{"group end without a group", "names its group", ForgeGroupEnd{Members: []GroupMerge{{Repository: "a/b", Number: 1, Merge: "m"}}}},
+			{"group end with a member without its merge", "merge commit", ForgeGroupEnd{Group: "g", Members: []GroupMerge{{Repository: "a/b", Number: 1}}}},
+			{"group end with a member twice", "twice", ForgeGroupEnd{Group: "g", Members: []GroupMerge{{Repository: "a/b", Number: 1, Merge: "m"}, {Repository: "a/b", Number: 1, Merge: "m"}}}},
+		} {
+			if _, err := EncodeForgeGroupEnd(c.e); err == nil || !strings.Contains(err.Error(), c.want) {
+				t.Errorf("%s: %v, want a refusal naming %q", c.name, err, c.want)
+			}
+		}
+	})
+}
@@ -0,0 +1,5 @@
+module git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg
+
+go 1.26.0
+
+require git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261104002338-5a38a1221659
@@ -0,0 +1,14 @@
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261104002338-5a38a1221659 h1:tK7MzxVm/ECNg1Yblhh1ynVEthbZCg2mSPW0wQZC0b0=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261104002338-5a38a1221659/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
+github.com/klauspost/compress v1.20.0 h1:a3C1ke2ohxFymNlb2HWAHjDeKCI90scRskErZkR0ezA=
+github.com/klauspost/compress v1.20.0/go.mod h1:LUdAzn7YLVvxLpc7y3V1m40wESHTgc1422pwwBSKYuI=
+github.com/nats-io/nats.go v1.54.0 h1:vsXoOxjHp/GmPUN+EcI7uOf/uB+iAP+kEsAFNQN0yzA=
+github.com/nats-io/nats.go v1.54.0/go.mod h1:y+DZoD1oBOYfZTU681eTUiUjI0vbqYGixNVFHcjHJ0k=
+github.com/nats-io/nkeys v0.4.16 h1:rd5oAuLOb8mnAycB0xleuEBNS1pVVnN0fv/FF34Eypg=
+github.com/nats-io/nkeys v0.4.16/go.mod h1:llLgWoI0o4z/Q57q2R1kHfmocyhGV6VG/U18Glg1Afs=
+github.com/nats-io/nuid v1.0.1 h1:5iA8DT8V7q8WK2EScv2padNa/rTESc1KdnPw4TC2paw=
+github.com/nats-io/nuid v1.0.1/go.mod h1:19wcPz3Ph3q0Jbyiqsd0kePYG7A95tJPxeL+1OSON2c=
+golang.org/x/crypto v0.57.0 h1:3ZVCjf8Ggz7zneR/EHRVx68Ctf+2pmIMP2UFhh9cC6M=
+golang.org/x/crypto v0.57.0/go.mod h1:Fdz0i5U6CoizGwLda9DttjSk6qlZo25zYNtR+ycvuZA=
+golang.org/x/sys v0.48.0 h1:bbX/i/6MgT9BVLM9RT1thmxL04yeTAhbEz4SyadbXoo=
+golang.org/x/sys v0.48.0/go.mod h1:hNLxWAXmnKAxqDtdwIYC4bM9oQPEecfsnNMuSxOs3og=
@@ -0,0 +1,78 @@
+package forgemsg
+
+import (
+	"encoding/json"
+	"fmt"
+	"reflect"
+)
+
+// ForgeGroupEndEvent is the name of a delivery group's end on the forge bridge's stream (novox/hq ADR 0633 §4): the
+// bridge publishes it once every approved member of the group is merged, after the last member's merged message. It
+// has three parts, so no repository's forge event (`forge.<owner>.<name>.<kind>`) is ever this name.
+const ForgeGroupEndEvent = "forge.group.merged"
+
+// GroupMerge is one merged member of a delivery group: the repository as `<owner>/<name>`, its pull request and the
+// merge commit the forge made of it.
+type GroupMerge struct {
+	Repository string `json:"repository"`
+	Number     int    `json:"number"`
+	Merge      string `json:"merge"`
+}
+
+// ForgeGroupEnd is the body of ForgeGroupEndEvent: the group and every member merged in it, with its merge commit.
+// The indexer takes the members it holds in as one source revision once it hears it (ADR 0633 §4).
+type ForgeGroupEnd struct {
+	V       int          `json:"v"`
+	Group   string       `json:"group"`
+	Members []GroupMerge `json:"members"`
+}
+
+func (e ForgeGroupEnd) check() error {
+	if e.Group == "" {
+		return fmt.Errorf("delivery: a group's end names its group")
+	}
+	if len(e.Members) == 0 {
+		return fmt.Errorf("delivery: the end of the group %q names no member merged in it", e.Group)
+	}
+	seen := map[string]bool{}
+	for _, m := range e.Members {
+		if err := checkRepository(m.Repository); err != nil {
+			return err
+		}
+		if m.Number <= 0 || m.Merge == "" {
+			return fmt.Errorf("delivery: the member %s of the group %q's end needs its pull request number and merge commit", m.Repository, e.Group)
+		}
+		k := fmt.Sprintf("%s#%d", m.Repository, m.Number)
+		if seen[k] {
+			return fmt.Errorf("delivery: the end of the group %q names its member %s twice", e.Group, k)
+		}
+		seen[k] = true
+	}
+	return nil
+}
+
+// EncodeForgeGroupEnd is e as JSON at Version; it refuses an end with no group or no member, and a member without its
+// pull request or merge commit.
+func EncodeForgeGroupEnd(e ForgeGroupEnd) ([]byte, error) {
+	if err := e.check(); err != nil {
+		return nil, err
+	}
+	e.V = Version
+	return json.Marshal(e)
+}
+
+// DecodeForgeGroupEnd reads a group's end; it refuses an unknown version (ErrUnknownVersion) and what
+// EncodeForgeGroupEnd refuses.
+func DecodeForgeGroupEnd(data []byte) (ForgeGroupEnd, error) {
+	var e ForgeGroupEnd
+	if err := decode(data, &e); err != nil {
+		return ForgeGroupEnd{}, err
+	}
+	if err := e.check(); err != nil {
+		return ForgeGroupEnd{}, err
+	}
+	return e, nil
+}
+
+// SameForgeGroupEnd says whether two group ends are the same value.
+func SameForgeGroupEnd(a, b ForgeGroupEnd) bool { return reflect.DeepEqual(a, b) }
@@ -3,12 +3,13 @@ module mesh-delivery-forge-bridge
 go 1.26.0

 require (
-	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261103221822-85ba0a9a70d8
+	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261104002338-5a38a1221659
 	github.com/nats-io/nats-server/v2 v2.11.17
 	github.com/nats-io/nats.go v1.54.0
 )

 require (
+	git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg v0.0.0-00010101000000-000000000000
 	github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op // indirect
 	github.com/google/go-tpm v0.9.8 // indirect
 	github.com/klauspost/compress v1.20.0 // indirect
@@ -20,3 +21,5 @@ require (
 	golang.org/x/sys v0.48.0 // indirect
 	golang.org/x/time v0.15.0 // indirect
 )
+
+replace git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg => ./forgemsg
@@ -1,5 +1,5 @@
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261103221822-85ba0a9a70d8 h1:XEbIVImp6yGjA91rp0iZBoDdL5KfamjOuDLwWvqh0hc=
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261103221822-85ba0a9a70d8/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261104002338-5a38a1221659 h1:tK7MzxVm/ECNg1Yblhh1ynVEthbZCg2mSPW0wQZC0b0=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261104002338-5a38a1221659/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op h1:Z/MZK75wC/NSrkgqeNIa7jexam9uWzhLmFTSCPI/kn0=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op/go.mod h1:FQyySiasQQM8735Ddel3MRojmy4dA1IqCeyJ5jmPMbI=
 github.com/google/go-tpm v0.9.8 h1:slArAR9Ft+1ybZu0lBwpSmpwhRXaa85hWtMinMyRAWo=
@@ -5,6 +5,7 @@ import (
 	"slices"
 	"strings"

+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 )

@@ -145,11 +146,11 @@ func MergeActs(value []byte) ([]Act, error) {
 // RefusedMessage is the refused message the bridge writes on FORGE when the forge refuses an act: the act, the pull
 // request and head it was on, and the forge's own words.
 func RefusedMessage(a Act, words string) (Message, error) {
-	event, err := delivery.ForgeEvent(a.Repository, delivery.ForgeRefused)
+	event, err := forgemsg.ForgeEvent(a.Repository, forgemsg.ForgeRefused)
 	if err != nil {
 		return Message{}, err
 	}
-	body, err := delivery.EncodeForge(delivery.Forge{Kind: delivery.ForgeRefused, Repository: a.Repository, Number: a.Number,
+	body, err := forgemsg.EncodeForge(forgemsg.Forge{Kind: forgemsg.ForgeRefused, Repository: a.Repository, Number: a.Number,
 		Head: a.Head, Act: a.Name, Words: words})
 	if err != nil {
 		return Message{}, err
@@ -5,6 +5,7 @@ import (
 	"strings"
 	"testing"

+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 )

@@ -27,7 +28,7 @@ func owedValue(t *testing.T, repository string, number int, act string, o delive
 	return key, b
 }

-func TestOwedStatusIsACommitStatusCall(t *testing.T) { // 1341/AC1
+func TestOwedStatusIsACommitStatusCall(t *testing.T) { // 1341/AC1, K1
 	key, v := owedValue(t, "novox/mesh-delivery", 12, "status=mesh/merge-gate",
 		delivery.Owed{Act: delivery.OwedStatus, Context: "mesh/merge-gate", State: "pending", Text: "waiting", Target: "https://forge.example/novox/mesh-delivery/pulls/12"})
 	a, err := OwedAct(key, v)
@@ -42,6 +43,19 @@ func TestOwedStatusIsACommitStatusCall(t *testing.T) { // 1341/AC1
 	if a.Repository != "novox/mesh-delivery" || a.Number != 12 || a.Head != headA || a.Name != "status=mesh/merge-gate" {
 		t.Errorf("act = %+v", a)
 	}
+	// R4e findings K1 and R2-1 (issue 1301 S4; ADR 0503 §3, ADR 0521): no tool writes mesh/check, since a tool is told no
+	// caller and node-tools invokes every tool; the forge module writes it from the checker's owed state, and the bridge
+	// performs no mesh/check act.
+	ck, cv := checkerKV(t, delivery.Owed{Act: delivery.OwedStatus, Context: delivery.StatusContextCheck, State: "success", Text: "pass", Target: "https://view.example/checks/g.1"})
+	if a, err := OwedAct(ck, cv); err == nil || !strings.Contains(err.Error(), "mesh-delivery-checker.owed") {
+		t.Fatalf("OwedAct(mesh/check) = %+v, %v; want refused, naming where the forge module reads it", a, err)
+	}
+	// Nor through the gate's own owed bucket: the context is refused whichever key carries it.
+	gk, gv := owedValue(t, "novox/mesh-delivery", 12, "status=mesh/check",
+		delivery.Owed{Act: delivery.OwedStatus, Context: delivery.StatusContextCheck, State: "success", Text: "pass", Target: "https://x.example"})
+	if a, err := OwedAct(gk, gv); err == nil || !strings.Contains(err.Error(), "mesh-delivery-checker.owed") {
+		t.Fatalf("OwedAct(gate's mesh/check) = %+v, %v; want refused", a, err)
+	}
 }

 // checkerKV is the status the checker owes, as it writes it (mesh-sdk go/delivery CheckerOwedKey, EncodeCheckerOwed).
@@ -58,23 +72,6 @@ func checkerKV(t *testing.T, o delivery.Owed) (string, []byte) {
 	return key, v
 }

-// R4e findings K1 and R2-1 (issue 1301 S4; ADR 0503 §3, ADR 0521): no tool writes mesh/check, since a tool is told no
-// caller and node-tools invokes every tool; the forge module writes it from the checker's owed state, and the bridge
-// performs no mesh/check act.
-func TestOwedMeshCheckIsNoToolCall(t *testing.T) { // K1
-	key, v := checkerKV(t, delivery.Owed{Act: delivery.OwedStatus, Context: delivery.StatusContextCheck, State: "success", Text: "pass", Target: "https://view.example/checks/g.1"})
-	a, err := OwedAct(key, v)
-	if err == nil || !strings.Contains(err.Error(), "mesh-delivery-checker.owed") {
-		t.Fatalf("OwedAct(mesh/check) = %+v, %v; want refused, naming where the forge module reads it", a, err)
-	}
-	// Nor through the gate's own owed bucket: the context is refused whichever key carries it.
-	gk, gv := owedValue(t, "novox/mesh-delivery", 12, "status=mesh/check",
-		delivery.Owed{Act: delivery.OwedStatus, Context: delivery.StatusContextCheck, State: "success", Text: "pass", Target: "https://x.example"})
-	if a, err := OwedAct(gk, gv); err == nil || !strings.Contains(err.Error(), "mesh-delivery-checker.owed") {
-		t.Fatalf("OwedAct(gate's mesh/check) = %+v, %v; want refused", a, err)
-	}
-}
-
 func TestOwedViewNoteAndCommentCalls(t *testing.T) { // 1341/AC2
 	cases := []struct {
 		act  string
@@ -111,18 +108,12 @@ func TestOwedActWithoutAPullRequestNeedsOneOnlyWhereTheToolDoes(t *testing.T) {
 	}
 }

-func TestOwedActOfADottedRepositoryIsUnescaped(t *testing.T) {
-	key, v := owedValue(t, "novox/my.repo", 3, "comment.1", delivery.Owed{Act: delivery.OwedComment, Text: "x"})
-	a, err := OwedAct(key, v)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if a.Call.Args["repo"] != "my.repo" || a.Repository != "novox/my.repo" {
-		t.Errorf("act = %+v", a)
-	}
-}
-
 func TestOwedActThatDisagreesWithItsKeyIsRefused(t *testing.T) {
+	// A dotted repository's key is unescaped, and its act names the repository whole.
+	dk, dv := owedValue(t, "novox/my.repo", 3, "comment.1", delivery.Owed{Act: delivery.OwedComment, Text: "x"})
+	if a, err := OwedAct(dk, dv); err != nil || a.Call.Args["repo"] != "my.repo" || a.Repository != "novox/my.repo" {
+		t.Errorf("a dotted repository's act = %+v, %v", a, err)
+	}
 	key, _ := owedValue(t, "novox/mesh-delivery", 12, "view", delivery.Owed{Act: delivery.OwedView, Text: "v"})
 	v, _ := delivery.EncodeOwed(delivery.Owed{Act: delivery.OwedComment, Text: "v"})
 	if _, err := OwedAct(key, v); err == nil {
@@ -166,13 +157,11 @@ func TestMergeActsHandOnlyTheMemberHandedWithEveryApprovedHead(t *testing.T) { /
 	if acts[0].Name != "merge" || acts[0].Number != 12 || acts[0].Head != headA {
 		t.Errorf("act = %+v", acts[0])
 	}
-}
-
-func TestMergeActsOfAMergeWithoutApprovedHeadsAreRefused(t *testing.T) {
-	v := mergeValue(t, delivery.Merge{Group: "g", Ask: "a", Pulls: []delivery.MergePull{
+	// A merge with no approved heads is refused: the forge's tool would refuse it with nothing to say which.
+	v = mergeValue(t, delivery.Merge{Group: "g", Ask: "a", Pulls: []delivery.MergePull{
 		{Head: delivery.Head{Repository: "novox/mesh-delivery", Number: 12, Head: headA}, State: delivery.MergeMerging}}})
 	if _, err := MergeActs(v); err == nil {
-		t.Error("a merge with no approved heads was taken: the forge's tool would refuse it with nothing to say which")
+		t.Error("a merge with no approved heads was taken")
 	}
 }

@@ -185,13 +174,13 @@ func TestRefusedMessageNamesTheActAndTheForgesWords(t *testing.T) { // 1341/AC3,
 	if m.Event != "forge.novox.mesh-delivery.refused" {
 		t.Errorf("event = %q", m.Event)
 	}
-	f, err := delivery.DecodeForge(m.Data)
+	f, err := forgemsg.DecodeForge(m.Data)
 	if err != nil {
 		t.Fatal(err)
 	}
-	want := delivery.Forge{V: delivery.Version, Kind: delivery.ForgeRefused, Repository: "novox/mesh-delivery", Number: 12, Head: headA,
+	want := forgemsg.Forge{V: delivery.Version, Kind: forgemsg.ForgeRefused, Repository: "novox/mesh-delivery", Number: 12, Head: headA,
 		Act: "merge", Words: "novox/mesh-delivery#12 is not merged: its head moved"}
-	if !delivery.SameForge(f, want) {
+	if !forgemsg.SameForge(f, want) {
 		t.Errorf("message = %+v", f)
 	}
 }
@@ -15,7 +15,7 @@ import (
 	"strings"
 	"sync"

-	"git.novox.be/novox/mesh-sdk/go/delivery"
+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 )

 // ErrUnreadable is wrapped by every error that says an event cannot be turned into a message; it is never
@@ -110,11 +110,11 @@ func ConvertKept(subject string, data []byte, trees Trees, files Files, kept Kep
 	var action string
 	switch subject {
 	case UpdatedSubject:
-		action = delivery.PullUpdated
+		action = forgemsg.PullUpdated
 	case ClosedSubject:
-		action = delivery.PullClosed
+		action = forgemsg.PullClosed
 	case MergedSubject:
-		action = delivery.PullClosed // unless it merged into the trunk, below
+		action = forgemsg.PullClosed // unless it merged into the trunk, below
 	default:
 		return Message{}, fmt.Errorf("%w: %s", ErrNotHandled, subject)
 	}
@@ -136,29 +136,29 @@ func ConvertKept(subject string, data []byte, trees Trees, files Files, kept Kep
 		return merged(subject, p, trees, files, kept)
 	}
 	said := ""
-	if action == delivery.PullUpdated && p.Base != "" && p.Base != Trunk {
+	if action == forgemsg.PullUpdated && p.Base != "" && p.Base != Trunk {
 		// The checker judges pull requests into main only, and source.main names main's head only (novox/hq ADR 0484 §11): a
 		// pull request into another base is no candidate, as it is none at the start (OpenPulls) and at its merge. It is
 		// written closed, so a candidate an older head made is taken out, and said (issue 1422).
-		action = delivery.PullClosed
+		action = forgemsg.PullClosed
 		said = fmt.Sprintf("%s/%s#%d at %s is into %s, not %s: written closed, so it is no candidate; the checker judges pull requests into %s only (novox/hq ADR 0484 §11)",
 			p.Owner, p.Repo, p.Number, p.HeadSHA[:12], p.Base, Trunk, Trunk)
 	}
-	f := delivery.Forge{Kind: delivery.ForgePull, Repository: p.Owner + "/" + p.Repo, Branch: p.Head, Number: p.Number,
+	f := forgemsg.Forge{Kind: forgemsg.ForgePull, Repository: p.Owner + "/" + p.Repo, Branch: p.Head, Number: p.Number,
 		Head: p.HeadSHA, Action: action}
 	// The directories are the forge's word only when it said it could read them (module_dirs_said).
-	if action == delivery.PullUpdated && p.ModuleDirsSaid {
+	if action == forgemsg.PullUpdated && p.ModuleDirsSaid {
 		f.Dirs, f.DirsKnown = p.ModuleDirs, true
 		var err error
 		if f.Manifests, f.Locks, _, err = inputsRead(p.Owner, p.Repo, p.HeadSHA, p.ModuleDirs, files); err != nil {
 			return Message{}, fmt.Errorf("%w: %s: the manifests of %s/%s at the head %s: %v", ErrRetry, subject, p.Owner, p.Repo, p.HeadSHA, err)
 		}
 	}
-	event, err := delivery.ForgeEvent(f.Repository, delivery.ForgePull)
+	event, err := forgemsg.ForgeEvent(f.Repository, forgemsg.ForgePull)
 	if err != nil {
 		return Message{}, unreadable(subject, "%v", err)
 	}
-	body, err := delivery.EncodeForge(f)
+	body, err := forgemsg.EncodeForge(f)
 	if err != nil {
 		return Message{}, unreadable(subject, "%v", err)
 	}
@@ -313,11 +313,11 @@ func merged(subject string, p pull, trees Trees, files Files, kept Kept) (Messag
 	if len(locks) == 0 {
 		locks = nil
 	}
-	event, err := delivery.ForgeEvent(repository, delivery.ForgeMerged)
+	event, err := forgemsg.ForgeEvent(repository, forgemsg.ForgeMerged)
 	if err != nil {
 		return Message{}, unreadable(subject, "%v", err)
 	}
-	f := delivery.Forge{Kind: delivery.ForgeMerged, Repository: repository, Branch: p.Head, Number: p.Number,
+	f := forgemsg.Forge{Kind: forgemsg.ForgeMerged, Repository: repository, Branch: p.Head, Number: p.Number,
 		Head: p.HeadSHA, Merge: p.MergeSHA, Root: root, Trees: dirs, Manifests: manifests, Locks: locks}
 	if repository == CatalogRepository {
 		// The catalogue's predefined list at the merge (novox/hq ADR 0565 §2): the indexer keeps it for mesh-config.
@@ -331,7 +331,7 @@ func merged(subject string, p pull, trees Trees, files Files, kept Kept) (Messag
 			f.Predefined = json.RawMessage(raw)
 		}
 	}
-	body, err := delivery.EncodeForge(f)
+	body, err := forgemsg.EncodeForge(f)
 	if err != nil {
 		return Message{}, unreadable(subject, "%v", err)
 	}
@@ -373,12 +373,12 @@ func OpenPulls(answer []byte) (msgs []Message, skipped []string, err error) {
 			skipped = append(skipped, name+": it names no owner, repo, number, branch or 40-hex head")
 			continue
 		}
-		f := delivery.Forge{Kind: delivery.ForgePull, Repository: p.Owner + "/" + p.Repo, Branch: p.Head, Number: p.Number,
-			Head: p.HeadSHA, Action: delivery.PullUpdated}
-		event, err := delivery.ForgeEvent(f.Repository, delivery.ForgePull)
+		f := forgemsg.Forge{Kind: forgemsg.ForgePull, Repository: p.Owner + "/" + p.Repo, Branch: p.Head, Number: p.Number,
+			Head: p.HeadSHA, Action: forgemsg.PullUpdated}
+		event, err := forgemsg.ForgeEvent(f.Repository, forgemsg.ForgePull)
 		var body []byte
 		if err == nil {
-			body, err = delivery.EncodeForge(f)
+			body, err = forgemsg.EncodeForge(f)
 		}
 		if err != nil {
 			skipped = append(skipped, name+": "+err.Error())
@@ -392,12 +392,12 @@ func OpenPulls(answer []byte) (msgs []Message, skipped []string, err error) {
 // Track says what a message the bridge wrote changes in the head it keeps for each pull request (the bucket heads,
 // novox/hq ADR 0443 §5): the key `<owner>.<name>.<number>`, and the head to keep under it, or "" to take the key away
 // (a closed pull request, a merged one). ok is false for a message that keeps no head.
-func Track(f delivery.Forge) (key, head string, ok bool) {
+func Track(f forgemsg.Forge) (key, head string, ok bool) {
 	key = strings.ReplaceAll(f.Repository, "/", ".") + "." + strconv.Itoa(f.Number)
 	switch {
-	case f.Kind == delivery.ForgePull && f.Action != delivery.PullClosed:
+	case f.Kind == forgemsg.ForgePull && f.Action != forgemsg.PullClosed:
 		return key, f.Head, true
-	case f.Kind == delivery.ForgePull || f.Kind == delivery.ForgeMerged:
+	case f.Kind == forgemsg.ForgePull || f.Kind == forgemsg.ForgeMerged:
 		return key, "", true
 	}
 	return "", "", false
@@ -413,22 +413,22 @@ func OpenMessage(answer []byte) (Message, error) {
 	if err := json.Unmarshal(answer, &a); err != nil || a.Pulls == nil {
 		return Message{}, fmt.Errorf("the answer of gitea_open_pulls is not {pulls: [...]}: %v", err)
 	}
-	open := []delivery.OpenPull{}
+	open := []forgemsg.OpenPull{}
 	for _, p := range *a.Pulls {
 		if p.Base != Trunk || p.Owner == "" || p.Repo == "" || p.Number <= 0 {
 			continue
 		}
-		open = append(open, delivery.OpenPull{Repository: p.Owner + "/" + p.Repo, Number: p.Number})
+		open = append(open, forgemsg.OpenPull{Repository: p.Owner + "/" + p.Repo, Number: p.Number})
 	}
-	slices.SortFunc(open, func(a, b delivery.OpenPull) int {
+	slices.SortFunc(open, func(a, b forgemsg.OpenPull) int {
 		if c := strings.Compare(a.Repository, b.Repository); c != 0 {
 			return c
 		}
 		return a.Number - b.Number
 	})
-	body, err := delivery.EncodeForge(delivery.Forge{Kind: delivery.ForgeOpen, Open: open})
+	body, err := forgemsg.EncodeForge(forgemsg.Forge{Kind: forgemsg.ForgeOpen, Open: open})
 	if err != nil {
 		return Message{}, fmt.Errorf("the open pull requests cannot be said: %w", err)
 	}
-	return Message{Event: delivery.OpenEvent(), Data: body}, nil
+	return Message{Event: forgemsg.OpenEvent(), Data: body}, nil
 }
@@ -6,6 +6,7 @@ import (
 	"strings"
 	"testing"

+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 )

@@ -54,13 +55,13 @@ func TestUpdatedBecomesAPullMessage(t *testing.T) { // 1235/AC2 (the conversion;
 	if msg.Event != "forge.novox.mesh-delivery.pull" {
 		t.Errorf("event = %q", msg.Event)
 	}
-	f, err := delivery.DecodeForge(msg.Data)
+	f, err := forgemsg.DecodeForge(msg.Data)
 	if err != nil {
 		t.Fatal(err)
 	}
-	want := delivery.Forge{V: delivery.Version, Kind: delivery.ForgePull, Repository: "novox/mesh-delivery", Branch: "feat/x", Number: 12,
-		Head: head, Action: delivery.PullUpdated, Dirs: []string{"modules/a"}, DirsKnown: true, Manifests: map[string]string{"modules/a": "{}"}}
-	if !delivery.SameForge(f, want) {
+	want := forgemsg.Forge{V: delivery.Version, Kind: forgemsg.ForgePull, Repository: "novox/mesh-delivery", Branch: "feat/x", Number: 12,
+		Head: head, Action: forgemsg.PullUpdated, Dirs: []string{"modules/a"}, DirsKnown: true, Manifests: map[string]string{"modules/a": "{}"}}
+	if !forgemsg.SameForge(f, want) {
 		t.Errorf("message = %+v, want %+v", f, want)
 	}
 }
@@ -70,7 +71,7 @@ func TestDirsNotSaidAreNotKnown(t *testing.T) { // 1235/AC3
 	if err != nil {
 		t.Fatal(err)
 	}
-	f, _ := delivery.DecodeForge(msg.Data)
+	f, _ := forgemsg.DecodeForge(msg.Data)
 	if f.DirsKnown || len(f.Dirs) != 0 {
 		t.Errorf("dirs = %v known = %v, want not known", f.Dirs, f.DirsKnown)
 	}
@@ -79,7 +80,7 @@ func TestDirsNotSaidAreNotKnown(t *testing.T) { // 1235/AC3
 	if err != nil {
 		t.Fatal(err)
 	}
-	f, _ = delivery.DecodeForge(msg.Data)
+	f, _ = forgemsg.DecodeForge(msg.Data)
 	if !f.DirsKnown || len(f.Dirs) != 0 {
 		t.Errorf("dirs = %v known = %v, want known and empty", f.Dirs, f.DirsKnown)
 	}
@@ -88,7 +89,7 @@ func TestDirsNotSaidAreNotKnown(t *testing.T) { // 1235/AC3
 	if err != nil {
 		t.Fatal(err)
 	}
-	if f, _ = delivery.DecodeForge(msg.Data); f.DirsKnown || len(f.Dirs) != 0 {
+	if f, _ = forgemsg.DecodeForge(msg.Data); f.DirsKnown || len(f.Dirs) != 0 {
 		t.Errorf("dirs %v known %v without module_dirs_said", f.Dirs, f.DirsKnown)
 	}
 }
@@ -101,13 +102,13 @@ func TestClosedBecomesAClosedPullMessage(t *testing.T) { // 1235/AC4
 	if msg.Event != "forge.novox.mesh-delivery.pull" {
 		t.Errorf("event = %q", msg.Event)
 	}
-	f, err := delivery.DecodeForge(msg.Data)
+	f, err := forgemsg.DecodeForge(msg.Data)
 	if err != nil {
 		t.Fatal(err)
 	}
-	want := delivery.Forge{V: delivery.Version, Kind: delivery.ForgePull, Repository: "novox/mesh-delivery", Branch: "feat/x", Number: 12,
-		Head: head, Action: delivery.PullClosed}
-	if !delivery.SameForge(f, want) {
+	want := forgemsg.Forge{V: delivery.Version, Kind: forgemsg.ForgePull, Repository: "novox/mesh-delivery", Branch: "feat/x", Number: 12,
+		Head: head, Action: forgemsg.PullClosed}
+	if !forgemsg.SameForge(f, want) {
 		t.Errorf("message = %+v, want %+v", f, want)
 	}
 	// Issue 1422, ADR 0484 §11: a head pushed to a pull request into another base is written closed, read nothing for, and said;
@@ -116,12 +117,12 @@ func TestClosedBecomesAClosedPullMessage(t *testing.T) { // 1235/AC4
 	if err != nil {
 		t.Fatal(err)
 	}
-	if f, err = delivery.DecodeForge(msg.Data); err != nil || !delivery.SameForge(f, want) || !strings.Contains(msg.Said, "is into nox-mesh, not main") {
+	if f, err = forgemsg.DecodeForge(msg.Data); err != nil || !forgemsg.SameForge(f, want) || !strings.Contains(msg.Said, "is into nox-mesh, not main") {
 		t.Errorf("an update into nox-mesh is %+v (%v), said %q; want it closed and said", f, err, msg.Said)
 	}
 	for _, base := range []any{"main", nil} {
 		msg, err = Convert(updatedSubject, updated(map[string]any{"base": base}), nil, anyFiles)
-		if f, _ = delivery.DecodeForge(msg.Data); err != nil || f.Action != delivery.PullUpdated || msg.Said != "" {
+		if f, _ = forgemsg.DecodeForge(msg.Data); err != nil || f.Action != forgemsg.PullUpdated || msg.Said != "" {
 			t.Errorf("an update with base %v is %+v (%v), said %q; want it updated", base, f, err, msg.Said)
 		}
 	}
@@ -170,12 +171,18 @@ func mustDrop(body []byte, key string) []byte {
 	return b
 }

-func TestOtherSubjectsAreNotHandled(t *testing.T) { // 1235
+func TestOtherSubjectsAreNotHandled(t *testing.T) { // 1235, 1236
 	for _, s := range []string{"mesh.mod.gitea.event.something.else", "mesh.mod.other.event.pull.updated"} {
 		if _, err := Convert(s, updated(nil), nil, anyFiles); !errors.Is(err, ErrNotHandled) {
 			t.Errorf("%s: err = %v, want ErrNotHandled", s, err)
 		}
 	}
+	// 1236: a merged event without a full merge commit is unreadable, and the forge is not asked.
+	var calls []call
+	_, err := Convert(mergedSubject, mergedBody(map[string]any{"merge_commit_sha": "abc"}), treesOf(&calls, "r0", map[string]string{"a": "t"}, nil), anyFiles)
+	if !errors.Is(err, ErrUnreadable) || len(calls) != 0 {
+		t.Errorf("merged without a merge commit: err = %v calls = %v", err, calls)
+	}
 }

 const merge = "89abcdef0123456789abcdef0123456789abcdef"
@@ -222,13 +229,13 @@ func TestMergeIntoMainBecomesAMergedMessage(t *testing.T) { // 1236/AC1
 	if msg.Event != "forge.novox.mesh-delivery.merged" {
 		t.Errorf("event = %q", msg.Event)
 	}
-	f, err := delivery.DecodeForge(msg.Data)
+	f, err := forgemsg.DecodeForge(msg.Data)
 	if err != nil {
 		t.Fatal(err)
 	}
-	want := delivery.Forge{V: delivery.Version, Kind: delivery.ForgeMerged, Repository: "novox/mesh-delivery", Branch: "feat/x", Number: 12,
+	want := forgemsg.Forge{V: delivery.Version, Kind: forgemsg.ForgeMerged, Repository: "novox/mesh-delivery", Branch: "feat/x", Number: 12,
 		Head: head, Merge: merge, Root: "r0", Trees: answer, Manifests: map[string]string{"modules/a": "{}", "modules/b": "{}"}}
-	if !delivery.SameForge(f, want) {
+	if !forgemsg.SameForge(f, want) {
 		t.Errorf("message = %+v, want %+v", f, want)
 	}
 	if len(calls) != 1 || calls[0] != (call{"novox", "mesh-delivery", merge}) {
@@ -242,13 +249,13 @@ func TestMergeIntoAnotherBranchIsAClosedPull(t *testing.T) { // 1236/AC2
 	if err != nil {
 		t.Fatal(err)
 	}
-	f, err := delivery.DecodeForge(msg.Data)
+	f, err := forgemsg.DecodeForge(msg.Data)
 	if err != nil {
 		t.Fatal(err)
 	}
-	want := delivery.Forge{V: delivery.Version, Kind: delivery.ForgePull, Repository: "novox/mesh-delivery", Branch: "feat/x", Number: 12,
-		Head: head, Action: delivery.PullClosed}
-	if msg.Event != "forge.novox.mesh-delivery.pull" || !delivery.SameForge(f, want) {
+	want := forgemsg.Forge{V: delivery.Version, Kind: forgemsg.ForgePull, Repository: "novox/mesh-delivery", Branch: "feat/x", Number: 12,
+		Head: head, Action: forgemsg.PullClosed}
+	if msg.Event != "forge.novox.mesh-delivery.pull" || !forgemsg.SameForge(f, want) {
 		t.Errorf("event %q message %+v, want a closed pull message", msg.Event, f)
 	}
 	if len(calls) != 0 {
@@ -277,22 +284,14 @@ func TestNoModuleJSONAnywhereWritesAMergedMessageWithNoTrees(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	f, err := delivery.DecodeForge(msg.Data)
-	want := delivery.Forge{V: delivery.Version, Kind: delivery.ForgeMerged, Repository: "novox/mesh-delivery", Branch: "feat/x", Number: 12,
+	f, err := forgemsg.DecodeForge(msg.Data)
+	want := forgemsg.Forge{V: delivery.Version, Kind: forgemsg.ForgeMerged, Repository: "novox/mesh-delivery", Branch: "feat/x", Number: 12,
 		Head: head, Merge: merge, Root: "r0"}
-	if err != nil || msg.Event != "forge.novox.mesh-delivery.merged" || !delivery.SameForge(f, want) || !strings.Contains(msg.Said, "no module.json") {
+	if err != nil || msg.Event != "forge.novox.mesh-delivery.merged" || !forgemsg.SameForge(f, want) || !strings.Contains(msg.Said, "no module.json") {
 		t.Errorf("event %q message %+v said %q, %v; want a merged message with no trees", msg.Event, f, msg.Said, err)
 	}
 }

-func TestMergedWithoutAMergeCommitIsUnreadable(t *testing.T) { // 1236
-	var calls []call
-	_, err := Convert(mergedSubject, mergedBody(map[string]any{"merge_commit_sha": "abc"}), treesOf(&calls, "r0", map[string]string{"a": "t"}, nil), anyFiles)
-	if !errors.Is(err, ErrUnreadable) || len(calls) != 0 {
-		t.Errorf("err = %v calls = %v", err, calls)
-	}
-}
-
 // openAnswer is gitea_open_pulls's answer as mesh-catalog modules/gitea/client.ts:369-381 builds each entry
 // (owner, repo, number, base, head, head_sha, html_url, required, statuses, checks, labels) inside {pulls}.
 func openAnswer(pulls ...map[string]any) []byte {
@@ -311,12 +310,12 @@ func TestOpenPullsAreUpdatedPullMessagesWithUnknownDirs(t *testing.T) { // 1237/
 	if err != nil || len(skipped) != 0 || len(msgs) != 2 {
 		t.Fatalf("msgs %d skipped %v err %v", len(msgs), skipped, err)
 	}
-	for i, want := range []delivery.Forge{
-		{V: delivery.Version, Kind: delivery.ForgePull, Repository: "novox/mesh-delivery", Branch: "feat/x", Number: 12, Head: head, Action: delivery.PullUpdated},
-		{V: delivery.Version, Kind: delivery.ForgePull, Repository: "novox/mesh-catalog", Branch: "feat/x", Number: 300, Head: h2, Action: delivery.PullUpdated},
+	for i, want := range []forgemsg.Forge{
+		{V: delivery.Version, Kind: forgemsg.ForgePull, Repository: "novox/mesh-delivery", Branch: "feat/x", Number: 12, Head: head, Action: forgemsg.PullUpdated},
+		{V: delivery.Version, Kind: forgemsg.ForgePull, Repository: "novox/mesh-catalog", Branch: "feat/x", Number: 300, Head: h2, Action: forgemsg.PullUpdated},
 	} {
-		f, err := delivery.DecodeForge(msgs[i].Data)
-		if err != nil || !delivery.SameForge(f, want) {
+		f, err := forgemsg.DecodeForge(msgs[i].Data)
+		if err != nil || !forgemsg.SameForge(f, want) {
 			t.Errorf("message %d = %+v err %v, want %+v", i, f, err, want)
 		}
 		if f.DirsKnown {
@@ -328,14 +327,11 @@ func TestOpenPullsAreUpdatedPullMessagesWithUnknownDirs(t *testing.T) { // 1237/
 	}
 }

-func TestOpenPullIntoAnotherBranchGetsNoMessage(t *testing.T) { // 1237/AC4
-	msgs, skipped, err := OpenPulls(openAnswer(openEntry("mesh-delivery", 12, "feat/y", "feat/x", head)))
-	if err != nil || len(msgs) != 0 || len(skipped) != 0 {
-		t.Errorf("msgs %d skipped %v err %v, want none", len(msgs), skipped, err)
+func TestOpenPullsUnreadableEntryIsNamedAndTheRestGo(t *testing.T) { // 1237, 1237/AC4
+	// 1237/AC4: an open pull request into another branch gets no message.
+	if msgs, skipped, err := OpenPulls(openAnswer(openEntry("mesh-delivery", 12, "feat/y", "feat/x", head))); err != nil || len(msgs) != 0 || len(skipped) != 0 {
+		t.Errorf("into another branch: msgs %d skipped %v err %v, want none", len(msgs), skipped, err)
 	}
-}
-
-func TestOpenPullsUnreadableEntryIsNamedAndTheRestGo(t *testing.T) { // 1237
 	msgs, skipped, err := OpenPulls(openAnswer(openEntry("a", 1, "main", "b", "short"), openEntry("mesh-delivery", 12, "main", "feat/x", head)))
 	if err != nil || len(msgs) != 1 || len(skipped) != 1 || !strings.Contains(skipped[0], "novox/a#1") {
 		t.Errorf("msgs %d skipped %v err %v", len(msgs), skipped, err)
@@ -355,15 +351,15 @@ func TestOpenMessageNamesEveryOpenPullIntoTheTrunk(t *testing.T) { // 1279/AC6
 	if err != nil || m.Event != "forge.open" {
 		t.Fatalf("message %+v err %v", m, err)
 	}
-	f, err := delivery.DecodeForge(m.Data)
+	f, err := forgemsg.DecodeForge(m.Data)
 	// Every one into the trunk, whether its head reads or not (it is open); none into another branch; in a fixed order.
-	want := []delivery.OpenPull{{Repository: "novox/a", Number: 1}, {Repository: "novox/mesh-catalog", Number: 300}, {Repository: "novox/mesh-delivery", Number: 12}}
-	if err != nil || f.Kind != delivery.ForgeOpen || len(f.Open) != 3 || f.Open[0] != want[0] || f.Open[1] != want[1] || f.Open[2] != want[2] {
+	want := []forgemsg.OpenPull{{Repository: "novox/a", Number: 1}, {Repository: "novox/mesh-catalog", Number: 300}, {Repository: "novox/mesh-delivery", Number: 12}}
+	if err != nil || f.Kind != forgemsg.ForgeOpen || len(f.Open) != 3 || f.Open[0] != want[0] || f.Open[1] != want[1] || f.Open[2] != want[2] {
 		t.Errorf("open message = %+v err %v, want %v", f, err, want)
 	}
 	// Nothing open is a message too: the indexer then drops every candidate.
 	m, err = OpenMessage([]byte(`{"pulls":[]}`))
-	if f, derr := delivery.DecodeForge(m.Data); err != nil || derr != nil || f.Kind != delivery.ForgeOpen || len(f.Open) != 0 {
+	if f, derr := forgemsg.DecodeForge(m.Data); err != nil || derr != nil || f.Kind != forgemsg.ForgeOpen || len(f.Open) != 0 {
 		t.Errorf("empty answer: %+v %v %v", f, err, derr)
 	}
 	for _, bad := range []string{`{"pulls":null}`, `{}`, `x`} {
@@ -374,24 +370,24 @@ func TestOpenMessageNamesEveryOpenPullIntoTheTrunk(t *testing.T) { // 1279/AC6
 }

 func TestTrackSaysWhichHeadOfWhichPullRequestWasWritten(t *testing.T) { // 1279/AC6
-	pullMsg := func(action string) delivery.Forge {
-		return delivery.Forge{Kind: delivery.ForgePull, Repository: "novox/mesh-delivery", Branch: "feat/x", Number: 12, Head: head, Action: action}
+	pullMsg := func(action string) forgemsg.Forge {
+		return forgemsg.Forge{Kind: forgemsg.ForgePull, Repository: "novox/mesh-delivery", Branch: "feat/x", Number: 12, Head: head, Action: action}
 	}
-	for _, a := range []string{delivery.PullOpened, delivery.PullUpdated} {
+	for _, a := range []string{forgemsg.PullOpened, forgemsg.PullUpdated} {
 		if key, h, ok := Track(pullMsg(a)); key != "novox.mesh-delivery.12" || h != head || !ok {
 			t.Errorf("%s: Track = %q %q %v, want the head kept under a bucket key", a, key, h, ok)
 		}
 	}
 	// A closed pull request and a merged one are no longer kept: their key goes.
-	if key, h, ok := Track(pullMsg(delivery.PullClosed)); key != "novox.mesh-delivery.12" || h != "" || !ok {
+	if key, h, ok := Track(pullMsg(forgemsg.PullClosed)); key != "novox.mesh-delivery.12" || h != "" || !ok {
 		t.Errorf("closed: Track = %q %q %v", key, h, ok)
 	}
-	merged := delivery.Forge{Kind: delivery.ForgeMerged, Repository: "novox/mesh-delivery", Branch: "feat/x", Number: 12, Head: head, Merge: "m", Root: "r", Trees: map[string]string{"": "t"}}
+	merged := forgemsg.Forge{Kind: forgemsg.ForgeMerged, Repository: "novox/mesh-delivery", Branch: "feat/x", Number: 12, Head: head, Merge: "m", Root: "r", Trees: map[string]string{"": "t"}}
 	if key, h, ok := Track(merged); key != "novox.mesh-delivery.12" || h != "" || !ok {
 		t.Errorf("merged: Track = %q %q %v", key, h, ok)
 	}
 	// The open message and the rest hold no head.
-	if _, _, ok := Track(delivery.Forge{Kind: delivery.ForgeOpen}); ok {
+	if _, _, ok := Track(forgemsg.Forge{Kind: forgemsg.ForgeOpen}); ok {
 		t.Error("an open message was tracked")
 	}
 }
@@ -0,0 +1,79 @@
+package bridge
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"regexp"
+)
+
+// Caller calls a module's tool by its manifest key (`<module>.<tool>`) with a JSON body and returns the tool's result:
+// the bridge's process calls through the bus as its own principal, its tools bundle through the runtime (stdio.Ask).
+type Caller func(ctx context.Context, key string, body any) (json.RawMessage, error)
+
+// CommitTreesTool is the forge's tool for a commit's trees (mesh-catalog modules/gitea, issue 1234): arguments owner,
+// repo and sha, answer {root, trees}, the root directory spelled "" (1234/AC4).
+const CommitTreesTool = "gitea.gitea_commit_trees"
+
+// TreesVia asks the forge for a commit's trees through call.
+func TreesVia(ctx context.Context, call Caller) Trees {
+	return func(owner, repo, sha string) (string, map[string]string, error) {
+		raw, err := call(ctx, CommitTreesTool, map[string]string{"owner": owner, "repo": repo, "sha": sha})
+		if err != nil {
+			return "", nil, err
+		}
+		var a struct {
+			Root  string            `json:"root"`
+			Trees map[string]string `json:"trees"`
+		}
+		if err := json.Unmarshal(raw, &a); err != nil {
+			return "", nil, fmt.Errorf("the answer of %s is not {root, trees}: %w", CommitTreesTool, err)
+		}
+		if a.Root == "" {
+			return "", nil, fmt.Errorf("the answer of %s names no root tree", CommitTreesTool)
+		}
+		return a.Root, a.Trees, nil
+	}
+}
+
+// GetFileTool is the forge's tool for one file at a ref (mesh-catalog modules/gitea tools/index.ts gitea_get_file):
+// arguments owner, repo, path and ref, answer {file: {path, ref, sha, size, content}}, the content decoded to text
+// (client.ts getFile). A path the forge does not have fails with `Gitea API <path>: 404 <body>` (client.ts request).
+const GetFileTool = "gitea.gitea_get_file"
+
+// notFound is how the forge's error says 404 (client.ts request: `Gitea API ${path}: ${status} ${text}`; client.ts:670
+// recognises it as /: 404 /).
+var notFound = regexp.MustCompile(`: 404 `)
+
+// FilesVia asks the forge for a file through call. A file the forge says is not there is ErrNotFound.
+func FilesVia(ctx context.Context, call Caller) Files {
+	return func(owner, repo, path, ref string) ([]byte, error) {
+		raw, err := call(ctx, GetFileTool, map[string]string{"owner": owner, "repo": repo, "path": path, "ref": ref})
+		if err != nil {
+			if notFound.MatchString(err.Error()) {
+				return nil, fmt.Errorf("%w: %v", ErrNotFound, err)
+			}
+			return nil, err
+		}
+		var a struct {
+			File *struct {
+				Content *string `json:"content"`
+			} `json:"file"`
+		}
+		if err := json.Unmarshal(raw, &a); err != nil || a.File == nil || a.File.Content == nil {
+			return nil, fmt.Errorf("the answer of %s is not {file: {content}}: %v", GetFileTool, err)
+		}
+		return []byte(*a.File.Content), nil
+	}
+}
+
+// MergedMessage is the merged message of a merge into the trunk, asked again: built as the bridge builds the one it writes
+// on FORGE (it is that event's body through ConvertKept), from the pull request's owner, repository, number, branch, head
+// and merge commit, which the gate's merges state holds. It reads the forge for every module directory (no kept inputs).
+func MergedMessage(owner, repo string, number int, branch, head, merge string, trees Trees, files Files) (Message, error) {
+	body, err := json.Marshal(pull{Owner: owner, Repo: repo, Number: number, Head: branch, HeadSHA: head, Base: Trunk, MergeSHA: merge})
+	if err != nil {
+		return Message{}, err
+	}
+	return ConvertKept(MergedSubject, body, trees, files, nil)
+}
@@ -13,7 +13,7 @@ import (
 	"testing"
 	"time"

-	"git.novox.be/novox/mesh-sdk/go/delivery"
+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 )

 // The bytes the forge answers in these tests are two real files of this repository, read from the working tree: the
@@ -69,7 +69,7 @@ func TestMergedCarriesManifestsAndLocks(t *testing.T) { // 1448/AC1
 	if err != nil {
 		t.Fatal(err)
 	}
-	f, err := delivery.DecodeForge(msg.Data)
+	f, err := forgemsg.DecodeForge(msg.Data)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -90,7 +90,7 @@ func TestMergedCarriesManifestsAndLocks(t *testing.T) { // 1448/AC1
 	if err != nil {
 		t.Fatal(err)
 	}
-	if f, err = delivery.DecodeForge(msg.Data); err != nil {
+	if f, err = forgemsg.DecodeForge(msg.Data); err != nil {
 		t.Fatal(err)
 	}
 	if len(f.RetiredPlacements) > 0 || f.RetiredRead || strings.Contains(string(msg.Data), `"placements`) {
@@ -108,7 +108,7 @@ func TestMergedCarriesManifestsAndLocks(t *testing.T) { // 1448/AC1
 	}
 	forge.have[PredefinedFile] = []byte(`{"font-size":{"type":"integer","value":13}}`)
 	msg, _ = Convert(mergedSubject, mergedBody(map[string]any{"repo": "mesh-catalog"}), treesOf(&calls, "r0", map[string]string{"modules/a": "t1"}, nil), forge.get)
-	if f, err = delivery.DecodeForge(msg.Data); err != nil || string(f.Predefined) != string(forge.have[PredefinedFile]) || f.PredefinedRead {
+	if f, err = forgemsg.DecodeForge(msg.Data); err != nil || string(f.Predefined) != string(forge.have[PredefinedFile]) || f.PredefinedRead {
 		t.Errorf("predefined = %s (%v)", f.Predefined, err)
 	}
 	forge.calls = nil
@@ -133,7 +133,7 @@ func TestPullWithKnownDirsCarriesTheSameAtTheHead(t *testing.T) { // 1448/AC2
 	if err != nil {
 		t.Fatal(err)
 	}
-	f, _ := delivery.DecodeForge(msg.Data)
+	f, _ := forgemsg.DecodeForge(msg.Data)
 	if !reflect.DeepEqual(f.Manifests, map[string]string{"modules/a": string(manifest)}) || len(f.Locks) != 1 || len(f.Packages) != 0 {
 		t.Errorf("manifests %v locks %v packages %v", f.Manifests, f.Locks, f.Packages)
 	}
@@ -146,7 +146,7 @@ func TestPullWithKnownDirsCarriesTheSameAtTheHead(t *testing.T) { // 1448/AC2
 	if err != nil {
 		t.Fatal(err)
 	}
-	f, _ = delivery.DecodeForge(msg.Data)
+	f, _ = forgemsg.DecodeForge(msg.Data)
 	if f.Manifests != nil || f.Locks != nil || len(forge.calls) != 0 {
 		t.Errorf("manifests %v locks %v calls %v", f.Manifests, f.Locks, forge.calls)
 	}
@@ -175,7 +175,7 @@ func TestAForgeErrorOrAMissingManifestIsRetryAndALockNotFoundIsLeftOut(t *testin
 	if err != nil {
 		t.Fatal(err)
 	}
-	if f, _ := delivery.DecodeForge(msg.Data); f.Locks != nil {
+	if f, _ := forgemsg.DecodeForge(msg.Data); f.Locks != nil {
 		t.Errorf("locks = %v, want none for lock files the forge does not have", f.Locks)
 	}
 }
@@ -4,7 +4,7 @@ import (
 	"os"
 	"testing"

-	"git.novox.be/novox/mesh-sdk/go/delivery"
+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 )

 // ADR 0495 clause 1 with the lead's decision L8 of R4e: the forge bridge is no reader of a manifest's `paths`. A merge of a
@@ -26,7 +26,7 @@ func TestAMergedMessageCarriesNoNamedPathsTheBridgeDerived(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	f, err := delivery.DecodeForge(msg.Data)
+	f, err := forgemsg.DecodeForge(msg.Data)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -0,0 +1,198 @@
+// Package groups is what the forge bridge's process and its tools bundle share of a delivery group's end (novox/hq ADR
+// 0633 §4, issue 1585): the keys of the bridge's state performed, and the asks of the state end-asks, through which the
+// tool bridge_group_end_again asks the process to say a group's end again (the bridge serves no request subject, ADR 0437
+// §4, so a tool asks in a state the process watches, as indexer_take_in asks the indexer in takeins).
+package groups
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"slices"
+	"sort"
+	"strconv"
+	"strings"
+	"time"
+
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+)
+
+// The bridge's states the tools read and write.
+const (
+	// PerformedState is the bridge's state of what it performed and published.
+	PerformedState = "performed"
+	// EndAsksState is the state of asks to say a group's end again, keyed by the gate's merges key of the group.
+	EndAsksState = "end-asks"
+	// EndAsksBucket is its bucket on the bus.
+	EndAsksBucket = delivery.ForgeBridgeModule + "_" + EndAsksState
+)
+
+// Key is the key of performed that says a group's end is written: `groups.<merges key>`, its value the revision of the
+// gate's merges key it was worked out from.
+func Key(mergesKey string) string { return "groups." + mergesKey }
+
+// PublishedKey is the key of performed that says a member's merged message is written: `published.<16 hex digits of the
+// sha256 of <repository>#<number>@<merge>>`.
+func PublishedKey(repository string, number int, merge string) string {
+	sum := sha256.Sum256([]byte(fmt.Sprintf("%s#%d@%s", strings.ToLower(repository), number, merge)))
+	return "published." + hex.EncodeToString(sum[:8])
+}
+
+// EndID is the message id of a group's end, and of one said again by hand at a time: the stream's duplicate window drops a
+// second publish of the same id.
+func EndID(group, lastMerge, again string) string {
+	id := "group-end." + group + "." + lastMerge
+	if again != "" {
+		id += "." + again
+	}
+	return id
+}
+
+// AgainStamp is the time a hand ask appends to a group end's message id.
+func AgainStamp(at time.Time) string { return at.UTC().Format("20060102T150405.000000000Z") }
+
+// EndAsk is a value of the end-asks state: which group's end a person asked to be said again, why, who and when, and, once
+// the bridge read it, its answer.
+type EndAsk struct {
+	V        int       `json:"v"`
+	Group    string    `json:"group"`
+	Why      string    `json:"why,omitempty"`
+	By       string    `json:"by,omitempty"`
+	At       time.Time `json:"at"`
+	Written  bool      `json:"written,omitempty"`
+	Answer   string    `json:"answer,omitempty"`
+	Answered time.Time `json:"answered,omitzero"`
+}
+
+// Done says the ask is answered.
+func (a EndAsk) Done() bool { return !a.Answered.IsZero() }
+
+// NewEndAsk is the value bridge_group_end_again writes for a group: its key (the gate's merges key) and the value.
+func NewEndAsk(group, why, by string, at time.Time) (string, []byte, error) {
+	group = strings.TrimSpace(group)
+	if group == "" {
+		return "", nil, errors.New("name the group whose end is said again (group)")
+	}
+	key, err := delivery.MergesKey(group)
+	if err != nil {
+		return "", nil, err
+	}
+	data, err := json.Marshal(EndAsk{V: 1, Group: group, Why: strings.TrimSpace(why), By: by, At: at.UTC()})
+	return key, data, err
+}
+
+// DecodeEndAsk reads an end-asks value.
+func DecodeEndAsk(data []byte) (EndAsk, error) {
+	var a EndAsk
+	if err := json.Unmarshal(data, &a); err != nil {
+		return a, err
+	}
+	if a.V != 1 || a.Group == "" {
+		return a, errors.New("an end-asks value of no version 1 naming no group")
+	}
+	return a, nil
+}
+
+// Row is one group as bridge_groups answers it: the gate's merge of it and what the bridge kept of its end.
+type Row struct {
+	Key     string      `json:"key"`
+	Group   string      `json:"group"`
+	Members []RowMember `json:"members"`
+	Ended   bool        `json:"ended"`
+	EndedAt uint64      `json:"ended-at-revision,omitempty"`
+	Open    bool        `json:"open"`
+	Words   string      `json:"words"`
+	// LastEndAsk is the last ask to say the group's end again (bridge_group_end_again), its who, why and when, and the
+	// bridge's answer once it read it; absent when none was asked. The state end-asks keeps the last per group.
+	LastEndAsk *EndAsk `json:"last-end-ask,omitempty"`
+}
+
+// RowMember is one approved member of a group: its merge's state at the gate and whether its merged message is written.
+type RowMember struct {
+	Repository string `json:"repository"`
+	Number     int    `json:"number"`
+	State      string `json:"state"`
+	Commit     string `json:"commit,omitempty"`
+	Published  bool   `json:"published"`
+}
+
+// Rows are the groups the gate's merges hold with more than one member, each with what the bridge kept: ended (its end
+// written, the revision it was worked out from) or open (some member is not merged or its merged message not written, or its
+// end not written). merges is the gate's merges by key, performed the bridge's performed keys by key; unread are the gate's
+// keys that do not read. asks are the end-asks values by the same key; one that does not read is named unread as
+// `end-asks.<key>`.
+func Rows(merges map[string][]byte, performed map[string]bool, endedAt map[string]uint64, asks map[string][]byte) (rows []Row, unread []string) {
+	lastAsk := map[string]*EndAsk{}
+	for key, raw := range asks {
+		a, err := DecodeEndAsk(raw)
+		if err != nil {
+			unread = append(unread, EndAsksState+"."+key)
+			continue
+		}
+		lastAsk[key] = &a
+	}
+	for key, raw := range merges {
+		m, err := delivery.DecodeMerge(raw)
+		if err != nil {
+			unread = append(unread, key)
+			continue
+		}
+		if len(m.Approved) < 2 {
+			continue
+		}
+		r := Row{Key: key, Group: m.Group}
+		allMerged := true
+		for _, p := range m.Pulls {
+			pub := p.Commit != "" && performed[PublishedKey(p.Repository, p.Number, p.Commit)]
+			r.Members = append(r.Members, RowMember{Repository: p.Repository, Number: p.Number, State: string(p.State), Commit: p.Commit, Published: pub})
+			if p.State != delivery.MergeMerged || !pub {
+				allMerged = false
+			}
+		}
+		if len(m.Pulls) < len(m.Approved) {
+			allMerged = false
+		}
+		r.EndedAt, r.Ended = endedAt[key]
+		r.LastEndAsk = lastAsk[key]
+		r.Open = !r.Ended
+		switch {
+		case r.Ended:
+			r.Words = "its end is written"
+		case allMerged:
+			r.Words = "every member is merged and its message written, and its end is not written: bridge_group_end_again says it"
+		default:
+			r.Words = "gathered: not every member is merged and its merged message written"
+		}
+		rows = append(rows, r)
+	}
+	sortRows(rows)
+	sort.Strings(unread)
+	return rows, unread
+}
+
+func sortRows(rows []Row) { sort.Slice(rows, func(i, j int) bool { return rows[i].Key < rows[j].Key }) }
+
+// MembersOf are a merge's approved members with their heads, in the order of their keys.
+func MembersOf(m delivery.Merge) []delivery.Head {
+	var out []delivery.Head
+	for _, k := range slices.Sorted(func(yield func(string) bool) {
+		for k := range m.Approved {
+			if !yield(k) {
+				return
+			}
+		}
+	}) {
+		at := strings.LastIndex(k, "@")
+		if at < 0 {
+			continue
+		}
+		n, err := strconv.Atoi(k[at+1:])
+		if err != nil {
+			continue
+		}
+		out = append(out, delivery.Head{Repository: k[:at], Number: n, Head: m.Approved[k]})
+	}
+	return out
+}
@@ -28,12 +28,13 @@ type state struct {
 }

 type artifact struct {
-	Name     string `json:"name"`
-	Kind     string `json:"kind"`
-	Language string `json:"language"`
-	System   string `json:"system"`
-	From     string `json:"from"`
-	Binary   string `json:"binary"`
+	Name     string   `json:"name"`
+	Kind     string   `json:"kind"`
+	Language string   `json:"language"`
+	System   string   `json:"system"`
+	From     string   `json:"from"`
+	Binary   string   `json:"binary"`
+	Loads    []string `json:"loads"`
 }

 type manifest struct {
@@ -44,6 +45,7 @@ type manifest struct {
 	Streams      []stream          `json:"streams"`
 	State        []state           `json:"state"`
 	Reads        []string          `json:"reads"`
+	Tools        []string          `json:"tools"`
 	Invokes      []string          `json:"invokes"`
 	OwnSecrets   map[string]string `json:"own-secrets"`
 	SecretsOwner string            `json:"secrets-owner"`
@@ -107,11 +109,15 @@ func TestManifestDeclarations(t *testing.T) { // 1235/AC1
 	// §5), the revision of each key of the gate's buckets the bridge performed, so a key is performed once per
 	// revision (ADR 0437 §8; issue 1341), and what a merge read of each module directory by its tree, so a merge reads
 	// the forge only for the directories it changed (issue 1126).
-	if !reflect.DeepEqual(m.State, []state{{Name: "heads", History: 1}, {Name: "performed", History: 1}, {Name: "inputs", History: 1}}) { // 1279/AC6, 1341, 1126
-		t.Errorf("state = %+v, want the buckets heads, performed and inputs", m.State)
+	if !reflect.DeepEqual(m.State, []state{{Name: "heads", History: 1}, {Name: "performed", History: 1}, {Name: "inputs", History: 1}, {Name: "end-asks", History: 1}}) { // 1279/AC6, 1341, 1126, 1585
+		t.Errorf("state = %+v, want the buckets heads, performed, inputs and end-asks", m.State)
 	}
-	// No other state, no bus, no seat, no tool, no event (ADR 0437 §4; ADR 0521: no check.status).
-	for _, k := range []string{"logs", "emits", "claims", "provides", "requires", "uses", "defines-seats", "tools", "seat", "seats"} {
+	// 1585/T18: the tools read the groups and ask the bridge to say a group's end again, through its state end-asks. The tool bridge_merged_message answers a merge's merged message again (issue 1585).
+	if want := []string{"bridge_group_end_again", "bridge_groups", "bridge_merged_message"}; !reflect.DeepEqual(sorted(m.Tools), want) {
+		t.Errorf("tools = %v, want %v", m.Tools, want)
+	}
+	// No other state, no bus, no seat, no event (ADR 0437 §4; ADR 0521: no check.status).
+	for _, k := range []string{"logs", "emits", "claims", "provides", "requires", "uses", "defines-seats", "seat", "seats"} {
 		if _, ok := top[k]; ok {
 			t.Errorf("the manifest declares %q: the bridge has none", k)
 		}
@@ -143,8 +149,8 @@ func TestManifestProcess(t *testing.T) { // 1235/AC1
 	if _, bus := p["bus"]; bus {
 		t.Errorf("the process declares a bus: it runs on its own broker credential")
 	}
-	if len(m.Build.Artifacts) != 1 {
-		t.Fatalf("artifacts = %+v", m.Build.Artifacts)
+	if len(m.Build.Artifacts) != 2 || m.Build.Artifacts[1].Name != "tools" || m.Build.Artifacts[1].From != "cmd/mesh-delivery-forge-bridge-tools" {
+		t.Fatalf("artifacts = %+v, want the program and the tools bundle", m.Build.Artifacts)
 	}
 	a := m.Build.Artifacts[0]
 	if st, err := os.Stat(a.From); err != nil || !st.IsDir() || a.Binary != "mesh-delivery-forge-bridge" || !strings.HasSuffix(a.From, a.Binary) {
@@ -13,7 +13,13 @@
  "state": [
    { "name": "heads", "history": 1 },
    { "name": "performed", "history": 1 },
-    { "name": "inputs", "history": 1 }
+    { "name": "inputs", "history": 1 },
+    { "name": "end-asks", "history": 1 }
+  ],
+  "tools": [
+    "bridge_groups",
+    "bridge_group_end_again",
+    "bridge_merged_message"
  ],
  "reads": [
    "mesh-delivery-gate.merges",
@@ -75,6 +81,17 @@
        "system": "arch",
        "from": "cmd/mesh-delivery-forge-bridge",
        "binary": "mesh-delivery-forge-bridge"
+      },
+      {
+        "name": "tools",
+        "kind": "bundle",
+        "language": "go",
+        "system": "arch",
+        "from": "cmd/mesh-delivery-forge-bridge-tools",
+        "binary": "mesh-delivery-forge-bridge-tools",
+        "loads": [
+          "mesh-delivery-forge-bridge-tools"
+        ]
      }
    ]
  }
@@ -8,6 +8,7 @@ package main
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"os"
 	"strings"
@@ -191,8 +192,33 @@ func heldCounts(s stdio.KeptState) func() (index.OldSectionsCount, error) {
 	}
 }

+// keptRead is a state the tools bundle reads, as the index package reads a store: Get and Keys; it writes nothing.
+type keptRead struct{ s stdio.KeptState }
+
+func (k keptRead) Get(_ context.Context, key string) ([]byte, uint64, bool, error) {
+	e, err := k.s.Get(key)
+	if err != nil || e == nil {
+		return nil, 0, false, err
+	}
+	return e.Value, e.Revision, true, nil
+}
+
+func (k keptRead) Keys(context.Context) ([]string, error) { return k.s.Keys() }
+
+func (keptRead) Create(context.Context, string, []byte) error { return errReadOnly }
+
+func (keptRead) Update(context.Context, string, []byte, uint64) error { return errReadOnly }
+
+func (keptRead) Delete(context.Context, string, uint64) error { return errReadOnly }
+
+var errReadOnly = errors.New("the tools bundle only reads this state")
+
 func main() {
-	if err := stdio.Serve("", append(Tools(askTakeIn(stdio.State(index.TakeInsState), 25*time.Second), time.Now, stdio.State(index.VerdictsState), heldCounts(stdio.State(index.OldSectionsState))), catalogTools()...)); err != nil {
+	ask := askTakeIn(stdio.State(index.TakeInsState), 25*time.Second)
+	tools := append(Tools(ask, time.Now, stdio.State(index.VerdictsState), heldCounts(stdio.State(index.OldSectionsState))), catalogTools()...)
+	tools = append(tools, index.PendingTools(keptRead{stdio.State(index.PendingState)}, keptRead{stdio.State(index.OwnBuildStateName)}, ask, time.Now)...)
+	tools = append(tools, index.TryCandidateTools(keptRead{stdio.State("candidates")}, keptRead{stdio.State(index.TryRecoveryState)}, ask, time.Now)...)
+	if err := stdio.Serve("", tools); err != nil {
 		fmt.Fprintf(os.Stderr, "[mesh-delivery-indexer-tools] %v\n", err)
 		os.Exit(1)
 	}
@@ -0,0 +1,32 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+)
+
+// mergedTool is the forge bridge's tool that answers a merge's merged message again (issue 1585): arguments repository
+// and merge, answer {message}, the message whole as the bridge writes it on FORGE. The indexer's manifest lists it in
+// invokes, which is the grant to call it.
+const mergedTool = delivery.ForgeBridgeModule + ".bridge_merged_message"
+
+// messageVia asks the forge bridge for a merge's merged message, for a held merge the indexer does not hold in memory (a
+// restart, a new build). An error is the bridge's own words.
+func messageVia(call toolCaller) func(ctx context.Context, repository, merge string) ([]byte, error) {
+	return func(_ context.Context, repository, merge string) ([]byte, error) {
+		raw, err := call(mergedTool, map[string]string{"repository": repository, "merge": merge})
+		if err != nil {
+			return nil, err
+		}
+		var a struct {
+			Message json.RawMessage `json:"message"`
+		}
+		if err := json.Unmarshal(raw, &a); err != nil || len(a.Message) == 0 {
+			return nil, fmt.Errorf("the answer of %s is not {message}: %v", mergedTool, err)
+		}
+		return a.Message, nil
+	}
+}
@@ -9,7 +9,10 @@ import (
 	"io"
 	"os"
 	"path/filepath"
+	"slices"
 	"strings"
+	"sync"
+	"sync/atomic"
 	"testing"
 	"time"

@@ -17,9 +20,15 @@ import (
 	"github.com/nats-io/nats.go"
 	"github.com/nats-io/nats.go/jetstream"

+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-indexer/takein"
 	"git.novox.be/novox/mesh-sdk/go/buscompose"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 	"git.novox.be/novox/mesh-sdk/go/process"
+
+	"git.novox.be/novox/mesh-delivery/sdk/graph"
+
+	"mesh-delivery-indexer/internal/index"
 )

 // busConf is the shape of the composed accounts file (mesh-controller internal/broker): one account with JetStream, the
@@ -42,22 +51,89 @@ accounts {
 // bus with the stream FORGE and the indexer's durable <node>_<module> on it, the buckets the controller makes from the
 // manifest's state (mesh-delivery-indexer_candidates, history 10) and mesh-controller_builds holding build records, and
 // no mesh-delivery-gate_source bucket.
-func TestIndexerWhole(t *testing.T) { // 1238/AC2, AC10
-	js, ctx, candidates, _ := startIndexer(t, func(ctx context.Context, builds buildLog) {
+//
+// And the take-in step (ADR 0633, issue 1585 I8a, I8b): the indexer's states pending, verdicts, graph, taken and packages
+// and its stream take-in are there, mesh-build-go reported its toolchain, and the node-engine's composition answers the
+// build of the indexer that runs. A merge changing the indexer's own tree writes only the indexer's entry, its manifest,
+// its verdict and its key of the graph (and the packages it publishes); the rest is pending, said take-in.pending and
+// named by indexer_pending with the build it waits for. A group's first member is gathered meanwhile. Started again as
+// that build, the indexer takes the revision in and leaves the group gathered; the group's second member and its end
+// then make one take-in, said take-in.taken under the group's key.
+func TestIndexerWhole(t *testing.T) { // 1238/AC2, AC10; 1585/T14, T15
+	var running atomic.Pointer[string]
+	first := "fp-the-indexer-that-runs"
+	running.Store(&first)
+	// The forge bridge's tool bridge_merged_message (issue 1585): answers the merged message published for a merge, by
+	// repository@merge, as the bridge does; a restarted indexer holds none in memory and asks it.
+	var bridgeMessages sync.Map
+	js, ctx, candidates, _, restart := startIndexerRun(t, func(ctx context.Context, builds buildLog) {
 		// The builder's log entries of two builds' ends (ADR 0571 clause 1), as the builder appends them.
 		builds.end(t, "novox/mesh-delivery", "a", "modules/a")
 		builds.end(t, "novox/mesh-catalog", "c", "modules/c")
-	})
-	h1, h2 := "0123456789abcdef0123456789abcdef01234567", "89abcdef0123456789abcdef0123456789abcdef"
-	for _, f := range []delivery.Forge{
-		{Kind: delivery.ForgePull, Repository: "novox/mesh-delivery", Branch: "feat/x", Number: 12, Head: h1, Action: delivery.PullUpdated, Dirs: []string{"modules/a"}, DirsKnown: true},
-		{Kind: delivery.ForgePull, Repository: "novox/mesh-catalog", Branch: "feat/x", Number: 300, Head: h2, Action: delivery.PullUpdated, Dirs: []string{"modules/c"}, DirsKnown: true},
-	} {
-		data, err := delivery.EncodeForge(f)
+	}, func(ctx context.Context, js jetstream.JetStream) {
+		// The states and the stream the controller makes from the indexer's manifest (old sections, ADR 0595 §11).
+		for bucket, history := range map[string]uint8{index.PendingBucket: 1, delivery.VerdictsBucket: delivery.VerdictsHistory,
+			graph.Bucket: 1, delivery.TakenBucket: 1, delivery.PackagesBucket: 1} {
+			if _, err := js.CreateKeyValue(ctx, jetstream.KeyValueConfig{Bucket: bucket, History: history}); err != nil {
+				t.Fatal(err)
+			}
+		}
+		// The take-in events are the indexer's ordinary events (ADR 0633 §5), on the path manifest-accepted takes.
+		for name, subject := range map[string]string{"INDEXER_EVENTS": "mesh.mod.mesh-delivery-indexer.event.>"} {
+			if _, err := js.CreateStream(ctx, jetstream.StreamConfig{Name: name, Subjects: []string{subject}}); err != nil {
+				t.Fatal(err)
+			}
+		}
+		tc, err := js.CreateKeyValue(ctx, jetstream.KeyValueConfig{Bucket: delivery.ToolchainsBucket("mesh-build-go"), History: 1})
 		if err != nil {
 			t.Fatal(err)
 		}
-		event, _ := delivery.ForgeEvent(f.Repository, delivery.ForgePull)
+		key, _ := delivery.ToolchainKey("n1", "go")
+		value, err := delivery.EncodeToolchain(delivery.Toolchain{Language: "go", Version: "go1.27.1", Recipe: "1", At: time.Now()})
+		if err != nil {
+			t.Fatal(err)
+		}
+		if _, err := tc.Put(ctx, key, value); err != nil {
+			t.Fatal(err)
+		}
+		// The node-engine's composition on n1 (process.Conn.Call's subjects): the build of the indexer that runs there.
+		answer := func(m *nats.Msg) {
+			raw, _ := json.Marshal(map[string]any{"result": map[string]any{"runs": map[string]string{"fp": *running.Load()}}, "node": "n1"})
+			_ = m.Respond(raw)
+		}
+		bridge := func(m *nats.Msg) {
+			var ask struct{ Repository, Merge string }
+			_ = json.Unmarshal(m.Data, &ask)
+			data, ok := bridgeMessages.Load(ask.Repository + "@" + ask.Merge)
+			if !ok {
+				raw, _ := json.Marshal(map[string]any{"error": "the gate holds no merge of " + ask.Repository + " with that commit"})
+				_ = m.Respond(raw)
+				return
+			}
+			raw, _ := json.Marshal(map[string]any{"result": map[string]any{"message": json.RawMessage(data.([]byte))}, "node": "n1"})
+			_ = m.Respond(raw)
+		}
+		for _, subject := range []string{"mesh.mod.mesh-delivery-forge-bridge.call.bridge_merged_message.>", "mesh.mod.mesh-delivery-forge-bridge.tool.bridge_merged_message"} {
+			if _, err := js.Conn().Subscribe(subject, bridge); err != nil {
+				t.Fatal(err)
+			}
+		}
+		for _, subject := range []string{"mesh.seat.node-engine.call.composition.n1.>", "mesh.seat.node-engine.tool.composition.n1"} {
+			if _, err := js.Conn().Subscribe(subject, answer); err != nil {
+				t.Fatal(err)
+			}
+		}
+	})
+	h1, h2 := "0123456789abcdef0123456789abcdef01234567", "89abcdef0123456789abcdef0123456789abcdef"
+	for _, f := range []forgemsg.Forge{
+		{Kind: forgemsg.ForgePull, Repository: "novox/mesh-delivery", Branch: "feat/x", Number: 12, Head: h1, Action: forgemsg.PullUpdated, Dirs: []string{"modules/a"}, DirsKnown: true},
+		{Kind: forgemsg.ForgePull, Repository: "novox/mesh-catalog", Branch: "feat/x", Number: 300, Head: h2, Action: forgemsg.PullUpdated, Dirs: []string{"modules/c"}, DirsKnown: true},
+	} {
+		data, err := forgemsg.EncodeForge(f)
+		if err != nil {
+			t.Fatal(err)
+		}
+		event, _ := forgemsg.ForgeEvent(f.Repository, forgemsg.ForgePull)
 		if _, err := js.Publish(ctx, "mesh.stream.mesh-delivery-forge-bridge.event."+event, data); err != nil {
 			t.Fatal(err)
 		}
@@ -83,11 +159,202 @@ func TestIndexerWhole(t *testing.T) { // 1238/AC2, AC10
 			t.Errorf("%s#%d modules = %v, want [%s]", p.Repository, p.Number, p.Modules, want)
 		}
 	}
+
+	// I8a: pull request 12 merged, changing the indexer's own tree and a's.
+	manifest, err := os.ReadFile("../../module.json")
+	if err != nil {
+		t.Fatal(err)
+	}
+	const ix = delivery.IndexerModule
+	m1 := forgemsg.Forge{Kind: forgemsg.ForgeMerged, Repository: "novox/mesh-delivery", Branch: "feat/x", Number: 12, Head: h1,
+		Merge: "1111111111111111111111111111111111111111", Root: "r0",
+		Trees:     map[string]string{"modules/" + ix: "tree-indexer-2", "modules/a": "tree-a-2"},
+		Manifests: map[string]string{"modules/" + ix: string(manifest), "modules/a": `{"module":"a","version":"1"}`},
+		Locks:     map[string]map[string]string{"modules/" + ix: {"go.sum": "3b5028f0c1e9bde04dd766abd63eb5931bc516bae695cf46f00abcd8510b0381"}}}
+	merged := func(f forgemsg.Forge) uint64 {
+		t.Helper()
+		data, err := forgemsg.EncodeForge(f)
+		if err != nil {
+			t.Fatal(err)
+		}
+		event, _ := forgemsg.ForgeEvent(f.Repository, forgemsg.ForgeMerged)
+		bridgeMessages.Store(f.Repository+"@"+f.Merge, data)
+		ack, err := js.Publish(ctx, "mesh.stream.mesh-delivery-forge-bridge.event."+event, data)
+		if err != nil {
+			t.Fatal(err)
+		}
+		return ack.Sequence
+	}
+	m1Key := takein.PendingKey(merged(m1))
+	events, err := js.Stream(ctx, "INDEXER_EVENTS")
+	if err != nil {
+		t.Fatal(err)
+	}
+	// saidAll is every take-in event of kind said under key so far, oldest first.
+	saidAll := func(kind, key string) []takein.TakeIn {
+		event, _ := takein.TakeInEvent(kind)
+		info, err := events.Info(ctx)
+		if err != nil {
+			t.Fatal(err)
+		}
+		var out []takein.TakeIn
+		for seq := info.State.FirstSeq; seq <= info.State.LastSeq && seq > 0; seq++ {
+			msg, err := events.GetMsg(ctx, seq)
+			if err != nil || msg.Subject != "mesh.mod."+ix+".event."+event {
+				continue
+			}
+			if ti, err := takein.DecodeTakeIn(msg.Data); err == nil && ti.Key == key {
+				out = append(out, ti)
+			}
+		}
+		return out
+	}
+	// said is the last take-in event under kind and key, within 20 s.
+	said := func(kind, key string) (takein.TakeIn, bool) {
+		for deadline := time.Now().Add(20 * time.Second); time.Now().Before(deadline); time.Sleep(50 * time.Millisecond) {
+			if all := saidAll(kind, key); len(all) > 0 {
+				return all[len(all)-1], true
+			}
+		}
+		return takein.TakeIn{}, false
+	}
+	held, ok := said(takein.TakeInPending, m1Key)
+	if !ok || held.What != takein.TakeInRevision || held.WaitsFor == "" || held.WaitsFor == first || len(held.Merges) != 1 {
+		t.Fatalf("take-in.pending.%s = %+v (said %v) within 20 s, want the revision waiting for another build than %s", m1Key, held, ok, first)
+	}
+	named := held.WaitsFor
+	get := func(bucket, key string) ([]byte, bool) {
+		t.Helper()
+		kv, err := js.KeyValue(ctx, bucket)
+		if err != nil {
+			t.Fatal(err)
+		}
+		e, err := kv.Get(ctx, key)
+		if err != nil {
+			return nil, false
+		}
+		return e.Value(), true
+	}
+	// Only what building and moving the named indexer needs is written.
+	raw, ok := get(delivery.ModulesBucket, ix)
+	own, err := delivery.DecodeModule(raw)
+	if !ok || err != nil || own.FP2 != named || own.Commit != m1.Merge {
+		t.Fatalf("modules.%s = %+v (%v), want the named build %s at the merge", ix, own, err, named)
+	}
+	if _, ok := get(delivery.ManifestsBucket, own.Manifest); !ok {
+		t.Errorf("manifests.%s is not written", own.Manifest)
+	}
+	if _, ok := get(delivery.VerdictsBucket, own.Manifest); !ok {
+		t.Errorf("the verdict on the indexer's manifest %s is not written", own.Manifest)
+	}
+	if gk, _ := graph.Key(ix); !func() bool { _, ok := get(graph.Bucket, gk); return ok }() {
+		t.Errorf("the indexer's key %s of the module graph is not written", gk)
+	}
+	repoKey, _ := delivery.RepositoryKey(m1.Repository)
+	if _, ok := get(delivery.ModulesBucket, "a"); ok {
+		t.Errorf("modules.a is written while the revision is pending")
+	}
+	if _, ok := get(delivery.TakenBucket, repoKey); ok {
+		t.Errorf("taken.%s is written while the revision is pending", repoKey)
+	}
+	if e, err := candidates.Get(ctx, "feat/x"); err != nil {
+		t.Errorf("the candidate feat/x is gone while the merge of #12 is pending: %v", err)
+	} else if c, err := delivery.DecodeCandidate(e.Value()); err != nil || len(c.Pulls) != 2 {
+		t.Errorf("the candidate feat/x = %+v while the merge of #12 is pending, want its two pull requests", c)
+	}
+
+	// A group's first member arrives meanwhile; its end is still to come (the knowledge base's remark: it stays across the restart).
+	members := []delivery.Head{{Repository: "novox/mesh-catalog", Number: 40, Head: "4040404040404040404040404040404040404040"},
+		{Repository: "novox/mesh-controller", Number: 41, Head: "4141414141414141414141414141414141414141"}}
+	g1 := forgemsg.Forge{Kind: forgemsg.ForgeMerged, Repository: "novox/mesh-catalog", Branch: "feat/g", Number: 40, Head: members[0].Head,
+		Merge: "4000000000000000000000000000000000000000", Root: "r0", Trees: map[string]string{"modules/c": "tree-c-2"},
+		Manifests: map[string]string{"modules/c": `{"module":"c","version":"1"}`}, Group: "feat/g", Members: members}
+	g2 := forgemsg.Forge{Kind: forgemsg.ForgeMerged, Repository: "novox/mesh-controller", Branch: "feat/g", Number: 41, Head: members[1].Head,
+		Merge: "4100000000000000000000000000000000000000", Root: "r0", Trees: map[string]string{"modules/k": "tree-k-1"},
+		Manifests: map[string]string{"modules/k": `{"module":"k","version":"1"}`}, Group: "feat/g", Members: members}
+	g1Key, groupKey := takein.PendingKey(merged(g1)), takein.GroupTakeInKey("feat/g")
+	if gathered, ok := said(takein.TakeInPending, groupKey); !ok || gathered.What != takein.TakeInGroup || len(gathered.Merges) != 1 {
+		t.Fatalf("take-in.pending.%s = %+v (said %v) within 20 s, want the group with its first member", groupKey, gathered, ok)
+	}
+	// indexer_pending, the tool over the same state, names both waits.
+	pendingKV, err := js.KeyValue(ctx, index.PendingBucket)
+	if err != nil {
+		t.Fatal(err)
+	}
+	waits := func() []takein.PendingWait {
+		t.Helper()
+		answer, err := index.PendingTools(kvStore{pendingKV}, nil, nil, time.Now)[0].Run(map[string]any{})
+		if err != nil {
+			t.Fatal(err)
+		}
+		return answer.(takein.PendingAnswer).Waits
+	}
+	var w []takein.PendingWait
+	for deadline := time.Now().Add(20 * time.Second); time.Now().Before(deadline); time.Sleep(50 * time.Millisecond) {
+		if w = waits(); len(w) == 2 && w[0].WaitsFor == named && w[1].Said != "" {
+			break
+		}
+	}
+	if len(w) != 2 || w[0].Key != m1Key || w[0].WaitsFor != named || !slices.Contains(w[0].Holds, "a") || !slices.Contains(w[0].Holds, ix) ||
+		w[1].Key != groupKey || w[1].What != takein.TakeInGroup || len(w[1].Merges) != 1 || w[1].Said != takein.TakeInPendingEvent {
+		t.Fatalf("indexer_pending = %+v, want the revision %s waiting for %s holding a and the indexer, then the group gathered", w, m1Key, named)
+	}
+
+	// The named indexer starts (the node-engine now runs that build): it takes the revision in, and leaves the group.
+	running.Store(&named)
+	restart()
+	if taken, ok := said(takein.TakeInTaken, m1Key); !ok || len(taken.Merges) != 1 || taken.Merges[0].Merge != m1.Merge {
+		t.Fatalf("take-in.taken.%s = %+v (said %v) within 20 s of the start of %s", m1Key, taken, ok, named)
+	}
+	for deadline := time.Now().Add(20 * time.Second); time.Now().Before(deadline); time.Sleep(50 * time.Millisecond) {
+		if w = waits(); len(w) == 1 {
+			break
+		}
+	}
+	if raw, ok := get(delivery.ModulesBucket, "a"); !ok || !strings.Contains(string(raw), m1.Merge) {
+		t.Errorf("modules.a = %s after the take-in at the start, want it at the merge %s", raw, m1.Merge)
+	}
+	if _, ok := get(delivery.TakenBucket, repoKey); !ok {
+		t.Errorf("taken.%s is not written by the take-in at the start", repoKey)
+	}
+	if len(w) != 1 || w[0].Key != groupKey || len(w[0].Keys) != 1 || w[0].Keys[0] != g1Key {
+		t.Fatalf("indexer_pending after the start = %+v, want only the group gathered, its first member %s", w, g1Key)
+	}
+	if _, ok := get(delivery.ModulesBucket, "c"); ok {
+		t.Errorf("modules.c is written while its group is gathered")
+	}
+
+	// I8b: the group's second member and its end: one take-in of both, said under the group's key.
+	merged(g2)
+	end, err := forgemsg.EncodeForgeGroupEnd(forgemsg.ForgeGroupEnd{Group: "feat/g", Members: []forgemsg.GroupMerge{
+		{Repository: g1.Repository, Number: g1.Number, Merge: g1.Merge}, {Repository: g2.Repository, Number: g2.Number, Merge: g2.Merge}}})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, err := js.Publish(ctx, "mesh.stream.mesh-delivery-forge-bridge.event."+forgemsg.ForgeGroupEndEvent, end); err != nil {
+		t.Fatal(err)
+	}
+	if taken, ok := said(takein.TakeInTaken, groupKey); !ok || taken.What != takein.TakeInGroup || len(taken.Merges) != 2 {
+		t.Fatalf("take-in.taken.%s = %+v (said %v) within 20 s of the group's end, want both members", groupKey, taken, ok)
+	}
+	var hasC, hasK bool
+	for deadline := time.Now().Add(20 * time.Second); time.Now().Before(deadline) && !(hasC && hasK && len(w) == 0); time.Sleep(50 * time.Millisecond) {
+		_, hasC = get(delivery.ModulesBucket, "c")
+		_, hasK = get(delivery.ModulesBucket, "k")
+		w = waits()
+	}
+	if !hasC || !hasK || len(w) != 0 {
+		t.Errorf("after the group's end: modules.c %v, modules.k %v, indexer_pending %+v: want both taken in and nothing waiting", hasC, hasK, w)
+	}
+	// One take-in: neither member was said as a revision of its own.
+	if len(saidAll(takein.TakeInPending, g1Key)) != 0 {
+		t.Errorf("the group's first member %s was said pending as a revision of its own", g1Key)
+	}
 }

-// startIndexer starts the bus, the stream FORGE with the indexer's durable consumer, the buckets, lets put fill
-// mesh-controller_builds, and runs the program. mesh-delivery-gate_source is never created.
-func startIndexer(t *testing.T, put func(context.Context, buildLog), before ...func(context.Context, jetstream.JetStream)) (jetstream.JetStream, context.Context, jetstream.KeyValue, jetstream.KeyValue) {
+// startIndexerRun starts the bus, the stream FORGE with the indexer's durable consumer, the buckets, lets put fill
+// mesh-controller_builds, and runs the program; restart starts it again. mesh-delivery-gate_source is never created.
+func startIndexerRun(t *testing.T, put func(context.Context, buildLog), before ...func(context.Context, jetstream.JetStream)) (jetstream.JetStream, context.Context, jetstream.KeyValue, jetstream.KeyValue, func()) {
 	dir, err := os.MkdirTemp(os.Getenv("TMPDIR"), "i")
 	if err != nil {
 		t.Fatal(err)
@@ -166,11 +433,24 @@ func startIndexer(t *testing.T, put func(context.Context, buildLog), before ...f
 		t.Fatal(err)
 	}
 	env := map[string]string{"MESH_BROKER_FILE": broker}
-	runCtx, stop := context.WithCancel(ctx)
-	done := make(chan error, 1)
-	go func() { done <- run(runCtx, func(k string) string { return env[k] }, io.Discard) }()
-	t.Cleanup(func() { stop(); <-done })
+	var stop func()
+	start := func() {
+		runCtx, cancel := context.WithCancel(ctx)
+		done := make(chan error, 1)
+		go func() { done <- run(runCtx, func(k string) string { return env[k] }, io.Discard) }()
+		stop = func() { cancel(); <-done }
+	}
+	start()
+	t.Cleanup(func() { stop() })
+	// restart stops the program and starts it again on the same bus, as the node-engine does with a new build.
+	restart := func() { stop(); start() }

+	return js, ctx, candidates, modules, restart
+}
+
+// startIndexer is startIndexerRun for a test that never starts the program again.
+func startIndexer(t *testing.T, put func(context.Context, buildLog), before ...func(context.Context, jetstream.JetStream)) (jetstream.JetStream, context.Context, jetstream.KeyValue, jetstream.KeyValue) {
+	js, ctx, candidates, modules, _ := startIndexerRun(t, put, before...)
 	return js, ctx, candidates, modules
 }

@@ -202,7 +482,7 @@ func TestIndexerWritesModulesAtAMerge(t *testing.T) { // 1239/AC9; I1, I3: the m
 		builds.end(t, "novox/mesh-controller", "build-agent", "modules/build-agent")
 	})
 	const merge = "89abcdef0123456789abcdef0123456789abcdef"
-	data, err := delivery.EncodeForge(delivery.Forge{Kind: delivery.ForgeMerged, Repository: "novox/mesh-delivery", Branch: "feat/x", Number: 12,
+	data, err := forgemsg.EncodeForge(forgemsg.Forge{Kind: forgemsg.ForgeMerged, Repository: "novox/mesh-delivery", Branch: "feat/x", Number: 12,
 		Head: "0123456789abcdef0123456789abcdef01234567", Merge: merge, Root: "r0", Trees: map[string]string{"modules/a": "newtree"},
 		Manifests: map[string]string{"modules/a": `{"module":"a","version":"1"}`}})
 	if err != nil {
@@ -256,7 +536,7 @@ func TestIndexerKeepsManifestsAtAMerge(t *testing.T) { // 1444/AC4, 1449/AC4, 15
 			t.Fatal(err)
 		}
 	})
-	forge := delivery.Forge{Kind: delivery.ForgeMerged, Repository: "novox/mesh-catalog", Branch: "feat/x", Number: 301,
+	forge := forgemsg.Forge{Kind: forgemsg.ForgeMerged, Repository: "novox/mesh-catalog", Branch: "feat/x", Number: 301,
 		Head: "0123456789abcdef0123456789abcdef01234567", Merge: "89abcdef0123456789abcdef0123456789abcdef", Root: "r0",
 		Trees:     map[string]string{"modules/avahi": "newtree"},
 		Manifests: map[string]string{"modules/avahi": string(manifest)},
@@ -264,7 +544,7 @@ func TestIndexerKeepsManifestsAtAMerge(t *testing.T) { // 1444/AC4, 1449/AC4, 15
 	for name, raw := range judged {
 		forge.Manifests["modules/"+name], forge.Trees["modules/"+name] = raw, "tree-"+name
 	}
-	data, err := delivery.EncodeForge(forge)
+	data, err := forgemsg.EncodeForge(forge)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -358,7 +638,7 @@ func TestIndexerWritesAGoModuleAgainWhenTheBuildModuleReportsItsToolchain(t *tes
 	js, ctx, _, modules := startIndexer(t, func(ctx context.Context, builds buildLog) {
 		builds.end(t, "novox/mesh-catalog", "avahi", "modules/avahi")
 	})
-	data, err := delivery.EncodeForge(delivery.Forge{Kind: delivery.ForgeMerged, Repository: "novox/mesh-catalog", Branch: "feat/x", Number: 301,
+	data, err := forgemsg.EncodeForge(forgemsg.Forge{Kind: forgemsg.ForgeMerged, Repository: "novox/mesh-catalog", Branch: "feat/x", Number: 301,
 		Head: "0123456789abcdef0123456789abcdef01234567", Merge: "89abcdef0123456789abcdef0123456789abcdef", Root: "r0",
 		Trees:     map[string]string{"modules/avahi": "newtree"},
 		Manifests: map[string]string{"modules/avahi": string(manifest)},
@@ -445,7 +725,7 @@ func TestIndexerGivesACandidateItsFingerprintWhenTheCheckerCreatesThePreviewsBuc
 			t.Fatal(err)
 		}
 	})
-	pull, err := delivery.EncodeForge(delivery.Forge{Kind: delivery.ForgePull, Repository: "novox/mesh-catalog", Branch: "feat/x", Number: 301, Head: head, Action: delivery.PullUpdated,
+	pull, err := forgemsg.EncodeForge(forgemsg.Forge{Kind: forgemsg.ForgePull, Repository: "novox/mesh-catalog", Branch: "feat/x", Number: 301, Head: head, Action: forgemsg.PullUpdated,
 		Dirs: []string{"modules/avahi"}, DirsKnown: true, Manifests: map[string]string{"modules/avahi": string(manifest)}})
 	if err != nil {
 		t.Fatal(err)
@@ -615,7 +895,7 @@ func TestIndexerCountsOnlyThePlacedBuildNodesToolchains(t *testing.T) {
 		place(ctx, t, "n1", "mesh-build-go")
 		place(ctx, t, "n2")
 	})
-	data, err := delivery.EncodeForge(delivery.Forge{Kind: delivery.ForgeMerged, Repository: "novox/mesh-catalog", Branch: "feat/x", Number: 302,
+	data, err := forgemsg.EncodeForge(forgemsg.Forge{Kind: forgemsg.ForgeMerged, Repository: "novox/mesh-catalog", Branch: "feat/x", Number: 302,
 		Head: "0123456789abcdef0123456789abcdef01234567", Merge: "89abcdef0123456789abcdef0123456789abcdef", Root: "r0",
 		Trees:     map[string]string{"modules/avahi": "newtree"},
 		Manifests: map[string]string{"modules/avahi": string(manifest)},
@@ -24,6 +24,7 @@ import (
 	"github.com/nats-io/nats.go/jetstream"

 	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-builder/buildrun"
+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 	stdio "git.novox.be/novox/mesh-sdk/go"
 	"git.novox.be/novox/mesh-sdk/go/delivery"

@@ -153,6 +154,34 @@ type delivered interface {
 	Metadata() (*jetstream.MsgMetadata, error)
 }

+// groupEndSubject is the whole subject of a delivery group's end on the forge bridge's stream: compared exactly, so a
+// repository named forge/group, whose merged message ends the same way, is never taken for one.
+var groupEndSubject = process.ModuleStreamSubject(delivery.ForgeBridgeModule, forgemsg.ForgeGroupEndEvent)
+
+// handleGroupEnd takes a group's end in (index.EndGroup): a body that does not read is terminated and said; an end
+// whose members are not all held yet, or while the build this program runs is not known, is left for redelivery.
+func handleGroupEnd(ctx context.Context, m delivered, ix *index.Indexer, h *index.Heard, logger *log.Logger) {
+	end, err := forgemsg.DecodeForgeGroupEnd(m.Data())
+	if err != nil {
+		logger.Printf("%s: not a group's end, dropped: %v", m.Subject(), err)
+		h.Outcome, h.Words = index.HeardDropped, err.Error()
+		_ = m.Term()
+		return
+	}
+	h.Kind, h.Branch = forgemsg.ForgeGroupEndEvent, end.Group
+	applied, words, err := ix.EndGroup(ctx, end)
+	h.Written, h.Late = applied.Written, applied.Late
+	if err != nil {
+		logger.Printf("%s: the end of the group %q left for redelivery: %v", m.Subject(), end.Group, err)
+		h.Outcome, h.Words = index.HeardLeft, err.Error()
+		return
+	}
+	h.Outcome, h.Words = index.HeardApplied, words
+	if err := m.DoubleAck(ctx); err != nil {
+		logger.Printf("%s: the end of the group %q applied, its acknowledgement was not confirmed: %v", m.Subject(), end.Group, err)
+	}
+}
+
 // handle takes one message of FORGE into the candidates and acknowledges it. A message it can never read is terminated,
 // never redelivered, and the log names its subject and why. A write that failed stays unacknowledged: the server
 // delivers it again (the server's ack wait is the only clock). Each message handled is written to the heard state
@@ -171,7 +200,12 @@ func handle(ctx context.Context, m delivered, ix *index.Indexer, heard index.Sto
 			logger.Printf("%s: sequence %d is not written to the heard state: %v", h.Subject, h.Sequence, err)
 		}
 	}()
-	f, err := delivery.DecodeForge(m.Data())
+	// A delivery group's end (novox/hq ADR 0633 §4) has a body of its own: told apart by its name, before the decode.
+	if m.Subject() == groupEndSubject {
+		handleGroupEnd(ctx, m, ix, &h, logger)
+		return
+	}
+	f, err := forgemsg.DecodeForge(m.Data())
 	if err != nil {
 		logger.Printf("%s: not a forge message, dropped: %v", m.Subject(), err)
 		h.Outcome, h.Words = index.HeardDropped, err.Error()
@@ -182,7 +216,13 @@ func handle(ctx context.Context, m delivered, ix *index.Indexer, heard index.Sto
 	if f.Merge != "" {
 		h.Commit = f.Merge
 	}
-	applied, err := ix.ApplyMessage(ctx, f)
+	var applied index.Applied
+	if f.Kind == forgemsg.ForgeMerged && h.Sequence > 0 {
+		// A merge is taken in only by the indexer its revision names (ADR 0633 §1): kept in pending until then.
+		applied, h.Words, err = ix.Arrive(ctx, h.Sequence, f)
+	} else {
+		applied, err = ix.ApplyMessage(ctx, f)
+	}
 	h.Written, h.Late = applied.Written, applied.Late
 	switch {
 	case errors.Is(err, index.ErrUnreadable):
@@ -303,12 +343,22 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 	oldSections := process.AwaitBucket(ctx, js, conn, index.OldSectionsBucket, "the count of the old sections is not kept, so the judge refuses no use of one", logger.Printf)
 	// The module graph (ADR 0603 §2): a state this delivery brings, bound when it appears; until then no graph is written.
 	graph := process.AwaitBucket(ctx, js, conn, graph.Bucket, "no module graph is written", logger.Printf)
-	ix := &index.Indexer{OldSections: awaitedStore{oldSections}, Store: kvStore{candidates}, Modules: kvStore{modules}, Manifests: kvStore{manifests}, Taken: awaitedStore{taken}, Builds: known,
+	ownBuildState := process.AwaitBucket(ctx, js, conn, index.OwnBuildBucket, "which build this indexer runs is not kept", logger.Printf)
+	tryRecovery := process.AwaitBucket(ctx, js, conn, index.TryRecoveryBucket, "how the recovery of the open tries went is not kept", logger.Printf)
+	ix := &index.Indexer{OwnBuildState: awaitedStore{ownBuildState}, TryRecovery: awaitedStore{tryRecovery}, OldSections: awaitedStore{oldSections}, Store: kvStore{candidates}, Modules: kvStore{modules}, Manifests: kvStore{manifests}, Taken: awaitedStore{taken}, Builds: known,
 		Verdicts: awaitedStore{verdicts}, SayRefused: sayRefused(js, cred, logger.Printf), SayAccepted: sayAccepted(js, cred, logger.Printf),
 		Predefined: awaitedStore{predefined}, ConfigCandidates: awaitedStore{configCandidates}, Logf: logger.Printf,
 		Named: namedVia(calls.Call), Trunk: trunkVia(calls.Call), Contains: containsVia(calls.Call), Read: readVia(calls.Call),
-		ReadOpen: openVia(calls.Call), Packages: awaitedStore{packages}, Files: filesVia(calls.Call), GoSum: goSumVia(calls.Call), GoMod: goModVia(calls.Call),
-		OwnBuild: ownBuildVia(calls.Call, cred.Node), Graph: awaitedStore{graph}}
+		ReadOpen: openVia(calls.Call), Packages: awaitedStore{packages}, Files: filesVia(calls.Call), GoSum: goSumVia(calls.Call), GoMod: goModVia(calls.Call), ReadFile: readFileVia(calls.Call),
+		OwnBuild: ownBuildVia(calls.Call, cred.Node), OpenTries: openTriesVia(calls.Call), Graph: awaitedStore{graph}, Message: messageVia(calls.Call),
+		// The take-in step (ADR 0633): its state pending and its stream take-in, both this delivery's, bound when they appear;
+		// until then every merge is taken in at once, as before.
+		Pending:   awaitedStore{process.AwaitBucket(ctx, js, conn, index.PendingBucket, "no merge is held for the indexer its revision names: each is taken in at once", logger.Printf)},
+		SayTakeIn: sayTakeIn(js, cred)}
+	// Which build this program is, fixed here once, before it hears any merge and never asked again (index.FixOwnBuild): the
+	// node-engine names the successor while it replaces this process, and an old process that learnt it later would take
+	// revisions in with its old judge.
+	ix.FixOwnBuild(ctx)
 	// The log's entries at the start are read before any fingerprint is computed or registered module indexed (below); each
 	// new one indexes the module it names when that module is registered and the bucket holds none (registered.go).
 	var started atomic.Bool
@@ -368,7 +418,9 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 			if !gate.Toolchain(module, key, value, deleted) {
 				return nil
 			}
-			return ix.Recompute(ctx)
+			// The modules written again, and pending evaluated again (ADR 0633 §1): the build a revision names moves with
+			// the toolchain.
+			return ix.ToolchainReported(ctx)
 		},
 		recompute: ix.Recompute}, logger)
 	if err := tools.start(); err != nil {
@@ -448,11 +500,27 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 		}
 		defer tc.Stop()
 	}
-	switch pcons, err := cred.EventConsumer(ctx, js, PreviewsStream); {
-	case err != nil:
-		logger.Printf("the consumer %s_%s on %s does not exist yet, so the checker's previews are not heard until the indexer starts again: %v", cred.Node, cred.Module, PreviewsStream, err)
-	default:
-		pc, err := process.HearEvents(pcons, func(m jetstream.Msg) { previews.Written(m) }, logger.Printf)
+	// The consumer on the checker's stream exists before the open tries are listed and is heard after (ADR 0638 §3): an event
+	// said between the call and the hearing waits in it, and a try that started or ended meanwhile is found either way.
+	pcons, perr := cred.EventConsumer(ctx, js, PreviewsStream)
+	if perr != nil {
+		logger.Printf("the consumer %s_%s on %s does not exist yet, so the checker's previews and tries are not heard until the indexer starts again: %v", cred.Node, cred.Module, PreviewsStream, perr)
+	}
+	// The pending revisions that name this build are taken in now, oldest first, before the consumer on the forge bridge's
+	// stream starts (ADR 0633 §2). When the build this program runs is not known yet, nothing waits for it: the consumer
+	// starts, and a merged message left unacknowledged asks the build again at its redelivery (clause 1). A hand take-in
+	// (indexer_take_in_pending) is answered at any time: the takeins watch runs already.
+	if _, words, err := ix.TakeInAtStart(ctx); err != nil {
+		return fmt.Errorf("the take-in at start: %w", err)
+	} else if words != "" {
+		logger.Printf("take-in at start: %s", words)
+	}
+	// The open tries are found again through the checker's tool: a try event missed while the indexer was down would leave a
+	// try with no candidate, or a candidate with no try. Not fatal: the events come, and a preview written writes the candidates.
+	// A recovery that fails is said (journal, and indexer_try_candidates) and the events are heard all the same.
+	_ = ix.RecoverTries(ctx)
+	if perr == nil {
+		pc, err := process.HearEvents(pcons, func(m jetstream.Msg) { previews.heardChecks(m) }, logger.Printf)
 		if err != nil {
 			return err
 		}
@@ -11,6 +11,7 @@ import (

 	"github.com/nats-io/nats.go/jetstream"

+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 	"git.novox.be/novox/mesh-sdk/go/delivery"

 	"mesh-delivery-indexer/internal/index"
@@ -73,8 +74,8 @@ const head = "0123456789abcdef0123456789abcdef01234567"
 func TestAMessageIsIndexedAndAcked(t *testing.T) { // 1238/AC2 (unit part)
 	st := &memStore{vals: map[string][]byte{}}
 	ix := &index.Indexer{Store: st, Builds: index.NewBuilds()}
-	data, _ := delivery.EncodeForge(delivery.Forge{Kind: delivery.ForgePull, Repository: "novox/mesh-delivery", Branch: "feat/x", Number: 12, Head: head,
-		Action: delivery.PullUpdated, Dirs: []string{"modules/a"}, DirsKnown: true})
+	data, _ := forgemsg.EncodeForge(forgemsg.Forge{Kind: forgemsg.ForgePull, Repository: "novox/mesh-delivery", Branch: "feat/x", Number: 12, Head: head,
+		Action: forgemsg.PullUpdated, Dirs: []string{"modules/a"}, DirsKnown: true})
 	m := &fakeMsg{subject: "mesh.stream.mesh-delivery-forge-bridge.event.forge.novox.mesh-delivery.pull", data: data}
 	heard := &memStore{vals: map[string][]byte{}}
 	handle(context.Background(), m, ix, heard, log.New(&bytes.Buffer{}, "", 0))
@@ -84,7 +85,7 @@ func TestAMessageIsIndexedAndAcked(t *testing.T) { // 1238/AC2 (unit part)
 	}
 	// Issue 1126 note 76: what the indexer heard of FORGE is readable (indexer_heard): subject, sequence, deliveries, time,
 	// repository, commit and what it did.
-	if h := heardOf(t, heard); h.Subject != m.subject || h.Sequence != 41 || h.Delivered != 2 || h.Published.Hour() != 13 || h.Kind != delivery.ForgePull ||
+	if h := heardOf(t, heard); h.Subject != m.subject || h.Sequence != 41 || h.Delivered != 2 || h.Published.Hour() != 13 || h.Kind != forgemsg.ForgePull ||
 		h.Repository != "novox/mesh-delivery" || h.Number != 12 || h.Commit != head || h.Outcome != index.HeardApplied || h.Handled.IsZero() {
 		t.Errorf("heard = %+v", h)
 	}
@@ -102,6 +103,31 @@ func TestAMessageThatIsNoForgeMessageIsTerminatedAndLogged(t *testing.T) { // 12
 	if h := heardOf(t, heard); h.Outcome != index.HeardDropped || h.Sequence != 41 || h.Words == "" {
 		t.Errorf("heard = %+v", h)
 	}
+	// 1585/T9 (ADR 0633 §4): a group's end is told apart by its name before the forge decode: one that reads is acked
+	// (an indexer with no pending state takes the members in one by one), one that does not is dropped as a group's end.
+	for _, c := range []struct {
+		data   string
+		termd  int
+		logged string
+	}{{`{"v":1,"group":"feat/x","members":[{"repository":"novox/mesh-sdk","number":3,"merge":"` + head + `"}]}`, 0, ""},
+		{`{"v":1,"group":"feat/x"}`, 1, "not a group's end"}} {
+		logs.Reset()
+		m := &fakeMsg{subject: "mesh.stream.mesh-delivery-forge-bridge.event." + forgemsg.ForgeGroupEndEvent, data: []byte(c.data)}
+		handle(context.Background(), m, &index.Indexer{Store: st, Builds: index.NewBuilds()}, heard, log.New(&logs, "", 0))
+		if m.termd != c.termd || m.acked+m.termd != 1 || !strings.Contains(logs.String(), c.logged) {
+			t.Errorf("group end %s: terminated %d acked %d log %q", c.data, m.termd, m.acked, logs.String())
+		}
+		if h := heardOf(t, heard); h.Kind != forgemsg.ForgeGroupEndEvent && c.termd == 0 {
+			t.Errorf("heard of a group's end = %+v", h)
+		}
+	}
+	// The repository forge/group's merged message ends as a group's end does: it is a forge message all the same.
+	logs.Reset()
+	m = &fakeMsg{subject: "mesh.stream.mesh-delivery-forge-bridge.event.forge.forge.group.merged", data: []byte(`{"v":1,"group":"feat/x","members":[{"repository":"novox/mesh-sdk","number":3,"merge":"` + head + `"}]}`)}
+	handle(context.Background(), m, &index.Indexer{Store: st, Builds: index.NewBuilds()}, heard, log.New(&logs, "", 0))
+	if !strings.Contains(logs.String(), "not a forge message") {
+		t.Errorf("forge/group's merged message read as a group's end: %q", logs.String())
+	}
 }

 func TestTheSourceMainKeyIsTakenAtItsRevision(t *testing.T) { // 1344/AC1 (the watch's side: key, revision, value)
@@ -9,6 +9,8 @@ import (
 	"path"
 	"strings"

+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
+	"git.novox.be/novox/mesh-delivery/sdk/tryevent"
 	"git.novox.be/novox/mesh-sdk/go/delivery"

 	"mesh-delivery-indexer/internal/fingerprint"
@@ -18,7 +20,7 @@ import (
 // commitTreesTool is the forge's tool for a commit's trees (mesh-catalog modules/gitea): with `paths`, by module directory
 // (the root spelled ""), the paths relative to it, it answers {root, trees, paths} with paths by directory then path, each
 // path's git object id; a path not at the commit fails the call naming it (the interface agreed in R4e; mesh-sdk
-// delivery.Forge.Paths; novox/hq ADR 0499 clause 3).
+// forgemsg.Forge.Paths; novox/hq ADR 0499 clause 3).
 const commitTreesTool = "gitea.gitea_commit_trees"

 // toolCaller calls a module's tool, `<module>.<tool>`, as the indexer's own account (mesh-sdk process.Conn.Call).
@@ -100,7 +102,7 @@ func filesVia(call toolCaller) func(ctx context.Context, repository, sha string,
 		}
 		for _, d := range dirs {
 			if _, ok := a.Files[d]; !ok {
-				return nil, fmt.Errorf("the answer of %s lists no files of %q", commitTreesTool, d)
+				return nil, fmt.Errorf("the answer of %s lists no files of %q: %w", commitTreesTool, d, index.ErrNotInTree)
 			}
 		}
 		return a.Files, nil
@@ -119,6 +121,12 @@ func goModVia(call toolCaller) func(ctx context.Context, repository, sha, dir st
 	return goFileVia(call, "go.mod")
 }

+// readFileVia reads one file of a repository at a commit by its path (gitea_get_file); a file the commit does not hold is
+// none. The seat definitions of a revision are read with it (seatsof.go).
+func readFileVia(call toolCaller) func(ctx context.Context, repository, sha, path string) ([]byte, error) {
+	return goFileVia(call, "")
+}
+
 // goFileVia reads one Go file of a module directory at a commit through the forge's get-file tool; a file the commit does
 // not hold is none.
 func goFileVia(call toolCaller, name string) func(ctx context.Context, repository, sha, dir string) ([]byte, error) {
@@ -128,7 +136,10 @@ func goFileVia(call toolCaller, name string) func(ctx context.Context, repositor
 			return nil, fmt.Errorf("%q is not <owner>/<name>", repository)
 		}
 		p := name
-		if dir != "" && dir != delivery.RootPath {
+		switch {
+		case name == "": // readFileVia: dir is the file's whole path
+			p = dir
+		case dir != "" && dir != delivery.RootPath:
 			p = dir + "/" + name
 		}
 		raw, err := call(getFileTool, map[string]string{"owner": owner, "repo": repo, "path": p, "ref": sha})
@@ -258,8 +269,8 @@ const (
 )

 // openVia asks the forge which pull requests into the trunk are open now (gitea_open_pulls), every repository's.
-func openVia(call toolCaller) func(ctx context.Context) ([]delivery.OpenPull, error) {
-	return func(context.Context) ([]delivery.OpenPull, error) {
+func openVia(call toolCaller) func(ctx context.Context) ([]forgemsg.OpenPull, error) {
+	return func(context.Context) ([]forgemsg.OpenPull, error) {
 		raw, err := call(openPullsTool, map[string]any{})
 		if err != nil {
 			return nil, err
@@ -275,12 +286,40 @@ func openVia(call toolCaller) func(ctx context.Context) ([]delivery.OpenPull, er
 		if err := json.Unmarshal(raw, &o); err != nil || o.Pulls == nil {
 			return nil, fmt.Errorf("the answer of %s is not {pulls}: %v", openPullsTool, err)
 		}
-		out := []delivery.OpenPull{}
+		out := []forgemsg.OpenPull{}
 		for _, p := range *o.Pulls {
 			if p.Base == trunkBranch && p.Number > 0 {
-				out = append(out, delivery.OpenPull{Repository: p.Owner + "/" + p.Repo, Number: p.Number})
+				out = append(out, forgemsg.OpenPull{Repository: p.Owner + "/" + p.Repo, Number: p.Number})
 			}
 		}
 		return out, nil
 	}
 }
+
+// openTriesTool is the checker's tool that lists the tries that wait or run (mesh-delivery-checker checker_tries).
+const openTriesTool = "mesh-delivery-checker.checker_tries"
+
+// openTriesVia lists the open tries through the checker's tool, never its state (ADR 0596).
+func openTriesVia(call toolCaller) func(ctx context.Context) ([]tryevent.Open, error) {
+	return func(context.Context) ([]tryevent.Open, error) {
+		raw, err := call(openTriesTool, map[string]any{})
+		if err != nil {
+			return nil, err
+		}
+		// No try open is an answer: the checker's list is empty, or null in an older checker (issue 1921). An answer without the
+		// key is none.
+		var o map[string]json.RawMessage
+		if err := json.Unmarshal(raw, &o); err != nil {
+			return nil, fmt.Errorf("the answer of %s is not {tries}: %v", openTriesTool, err)
+		}
+		list, ok := o["tries"]
+		if !ok {
+			return nil, fmt.Errorf("the answer of %s is not {tries}: no tries key", openTriesTool)
+		}
+		var tries []tryevent.Open
+		if err := json.Unmarshal(list, &tries); err != nil {
+			return nil, fmt.Errorf("the answer of %s is not {tries}: %v", openTriesTool, err)
+		}
+		return tries, nil
+	}
+}
@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/json"
 	"errors"
+	"mesh-delivery-indexer/internal/index"
 	"slices"
 	"strings"
 	"testing"
@@ -50,6 +51,15 @@ func TestTheTrunkIsTheDirectoriesTheForgeListsTrees(t *testing.T) { // 1900/AC3
 	if _, has := gotArgs.(map[string]any)["paths"]; has {
 		t.Error("the trunk asked for paths")
 	}
+	// A directory the answer lists no files of is a failure of the tree (index.ErrNotInTree); a call that fails is not.
+	noDir := func(string, any) (json.RawMessage, error) { return json.RawMessage(`{"files":{}}`), nil }
+	if _, err := filesVia(noDir)(context.Background(), "novox/mesh-sdk", strings.Repeat("a", 40), []string{"go"}); !errors.Is(err, index.ErrNotInTree) {
+		t.Errorf("a missing directory: %v, want ErrNotInTree", err)
+	}
+	down := func(string, any) (json.RawMessage, error) { return nil, errors.New("down") }
+	if _, err := filesVia(down)(context.Background(), "novox/mesh-sdk", strings.Repeat("a", 40), []string{"go"}); err == nil || errors.Is(err, index.ErrNotInTree) {
+		t.Errorf("a failed call: %v, want an error that is not ErrNotInTree", err)
+	}
 	// The build the indexer runs is the engine's word (Runs.FP of its composition verb), asked of its own machine.
 	var asked string
 	own := func(key string, body any) (json.RawMessage, error) {
@@ -59,10 +69,45 @@ func TestTheTrunkIsTheDirectoriesTheForgeListsTrees(t *testing.T) { // 1900/AC3
 	if fp, err := ownBuildVia(own, "n1")(context.Background()); err != nil || fp != "src2:abc" || asked != "seat:node-engine.composition@n1" {
 		t.Errorf("own build = %q %v asked %q", fp, err, asked)
 	}
+	// Issue 1921: the start during a replacement. What runs still names the old build, the want (composed by the node itself)
+	// the successor, which this process is: it fixes the successor. A want that is not self, or is removed, leaves what runs.
+	for _, row := range []struct{ name, answer, want string }{
+		{"replacing: runs old, want new and self", `{"runs":{"fp":"src2:old"},"want":{"fp":"src2:new","self":true}}`, "src2:new"},
+		{"a want the node does not compose", `{"runs":{"fp":"src2:old"},"want":{"fp":"src2:new"}}`, "src2:old"},
+		{"replacing: the apply of the want failed or is held", `{"runs":{"fp":"src2:old"},"want":{"fp":"src2:new","self":true},"attempt":{"fp":"src2:new","held":true}}`, "src2:old"},
+		{"replacing: an attempt of another build", `{"runs":{"fp":"src2:old"},"want":{"fp":"src2:new","self":true},"attempt":{"fp":"src2:older"}}`, "src2:new"},
+		{"the want already runs", `{"runs":{"fp":"src2:new"},"want":{"fp":"src2:new","self":true}}`, "src2:new"},
+		{"a removed want", `{"runs":{"fp":"src2:old"},"want":{"fp":"src2:new","self":true,"removed":true}}`, "src2:old"},
+		{"no build runs yet, want self", `{"want":{"fp":"src2:new","self":true}}`, "src2:new"},
+	} {
+		ask := func(string, any) (json.RawMessage, error) { return json.RawMessage(row.answer), nil }
+		if fp, err := ownBuildVia(ask, "n1")(context.Background()); err != nil || fp != row.want {
+			t.Errorf("%s: own build = %q %v, want %q", row.name, fp, err, row.want)
+		}
+	}
 	none := func(string, any) (json.RawMessage, error) { return json.RawMessage(`{}`), nil }
 	if _, err := ownBuildVia(none, "n1")(context.Background()); err == nil {
 		t.Error("an engine that says nothing runs gave a build")
 	}
+	// Issue 1921: the checker's list of open tries; none open is an answer, whether [] or null.
+	for _, row := range []struct {
+		name, answer string
+		want         int
+		refused      bool
+	}{
+		{"one open", `{"tries":[{"id":"try-1","state":"running","whole":true,"members":[{"repository":"novox/a","head":"h","trunk":"t"}]}]}`, 1, false},
+		{"an empty list", `{"tries":[]}`, 0, false},
+		{"null, as an older checker answers none", `{"tries":null}`, 0, false},
+		{"no tries key", `{}`, 0, true},
+		{"not json", `nope`, 0, true},
+		{"tries of another shape", `{"tries":{"a":1}}`, 0, true},
+	} {
+		call := func(string, any) (json.RawMessage, error) { return json.RawMessage(row.answer), nil }
+		got, err := openTriesVia(call)(context.Background())
+		if (err != nil) != row.refused || len(got) != row.want {
+			t.Errorf("%s: %d tries, error %v; want %d, refused %v", row.name, len(got), err, row.want, row.refused)
+		}
+	}
 }

 func TestReadViaReadsManifestsAndLocks(t *testing.T) {
@@ -25,10 +25,32 @@ func ownBuildVia(call toolCaller, node string) func(ctx context.Context) (string
 			Runs *struct {
 				FP string `json:"fp"`
 			} `json:"runs"`
+			Want *struct {
+				FP      string `json:"fp"`
+				Self    bool   `json:"self"`
+				Removed bool   `json:"removed"`
+			} `json:"want"`
+			// Attempt is the engine's last apply that did not end running (failed, or held), with the build it was of.
+			Attempt *struct {
+				FP string `json:"fp"`
+			} `json:"attempt"`
 		}
 		if err := json.Unmarshal(raw, &a); err != nil {
 			return "", fmt.Errorf("the answer of %s is not a composition: %w", compositionVerb, err)
 		}
+		// While the engine's apply of the want is in progress (what runs still names the old build, the want names another, and no
+		// attempt names that want as failed or held), this process is the successor and fixes the want's build. self is the node's
+		// standing way of composing the module, not a mark of this process, so it is not enough alone: an old process started again
+		// while the want names a successor that does not run (its apply failed or is held) takes what runs. The start fixes the
+		// build once (quick fix, ADR 0639 §7: nothing is learnt later, nothing waits on a timer); the thorough form is the
+		// engine passing each process the fingerprint it starts it with.
+		running := ""
+		if a.Runs != nil {
+			running = a.Runs.FP
+		}
+		if w := a.Want; w != nil && w.Self && !w.Removed && w.FP != "" && w.FP != running && (a.Attempt == nil || a.Attempt.FP != w.FP) {
+			return w.FP, nil
+		}
 		if a.Runs == nil || a.Runs.FP == "" {
 			return "", errors.New("the engine says no fingerprint of the indexer runs")
 		}
@@ -13,6 +13,7 @@ import (
 	"github.com/nats-io/nats.go"
 	"github.com/nats-io/nats.go/jetstream"

+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 	"git.novox.be/novox/mesh-sdk/go/buscompose"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 )
@@ -71,10 +72,10 @@ func TestAMeshSDKMergeMovesOnlyTheModulesImportingAChangedPackage(t *testing.T)
 		}
 		serveForge(t, js.Conn(), listing, goSumContent)
 	})
-	merged := func(repo string, number int, merge string, f delivery.Forge) {
+	merged := func(repo string, number int, merge string, f forgemsg.Forge) {
 		t.Helper()
-		f.Kind, f.Repository, f.Branch, f.Number, f.Head, f.Merge = delivery.ForgeMerged, repo, "feat/x", number, "0123456789abcdef0123456789abcdef01234567", merge
-		data, err := delivery.EncodeForge(f)
+		f.Kind, f.Repository, f.Branch, f.Number, f.Head, f.Merge = forgemsg.ForgeMerged, repo, "feat/x", number, "0123456789abcdef0123456789abcdef01234567", merge
+		data, err := forgemsg.EncodeForge(f)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -101,10 +102,10 @@ func TestAMeshSDKMergeMovesOnlyTheModulesImportingAChangedPackage(t *testing.T)
 			"tsconfig.json": "5555555555555555555555555555555555555555"}}
 	}
 	// mesh-sdk at m1, then the catalogue's two modules: their go.sum names mesh-sdk, read by the indexer itself.
-	merged("novox/mesh-sdk", 70, m1, delivery.Forge{Root: sdkRoot1, Trees: map[string]string{"": sdkRoot1},
+	merged("novox/mesh-sdk", 70, m1, forgemsg.Forge{Root: sdkRoot1, Trees: map[string]string{"": sdkRoot1},
 		Manifests: map[string]string{"": string(sdkManifest)}, Paths: sdkObjects("6666666666666666666666666666666666666666")})
 	module("mesh-sdk", func(m delivery.Module) bool { return m.Commit == m1 })
-	merged("novox/mesh-catalog", 301, catalogMerge, delivery.Forge{Root: "r0",
+	merged("novox/mesh-catalog", 301, catalogMerge, forgemsg.Forge{Root: "r0",
 		Trees:     map[string]string{"modules/importer": "t1", "modules/plain": "t2"},
 		Manifests: map[string]string{"modules/importer": named("importer"), "modules/plain": named("plain")},
 		Locks:     map[string]map[string]string{"modules/importer": {"go.sum": goSumHash}, "modules/plain": {"go.sum": goSumHash}}})
@@ -140,11 +141,11 @@ func TestAMeshSDKMergeMovesOnlyTheModulesImportingAChangedPackage(t *testing.T)
 	// over its named tree, is not written (issue 1758, ADR 0499 clause 6; the operator, 2026-10-25: a module's value moves
 	// only with the module).
 	const goOnly = "4444444444444444444444444444444444444444"
-	merged("novox/mesh-sdk", 72, goOnly, delivery.Forge{Root: "cccccccccccccccccccccccccccccccccccccccc",
+	merged("novox/mesh-sdk", 72, goOnly, forgemsg.Forge{Root: "cccccccccccccccccccccccccccccccccccccccc",
 		Trees: map[string]string{"": "cccccccccccccccccccccccccccccccccccccccc"}, Manifests: map[string]string{"": string(sdkManifest)},
 		Paths: sdkObjects("6666666666666666666666666666666666666666")})
 	// mesh-sdk merges a change of buildstep alone (its version moves: src changed too).
-	merged("novox/mesh-sdk", 71, m2, delivery.Forge{Root: sdk2, Trees: map[string]string{"": sdk2},
+	merged("novox/mesh-sdk", 71, m2, forgemsg.Forge{Root: sdk2, Trees: map[string]string{"": sdk2},
 		Manifests: map[string]string{"": string(sdkManifest)}, Paths: sdkObjects("7777777777777777777777777777777777777777")})
 	sdkAt2 := module("mesh-sdk", func(m delivery.Module) bool { return m.Commit == m2 })
 	if sdkAt2.Inputs2 == nil || !strings.HasPrefix(sdkAt2.Inputs2.Tree, delivery.NamedTreePrefix) {
@@ -11,6 +11,7 @@ import (

 	"github.com/nats-io/nats.go/jetstream"

+	"git.novox.be/novox/mesh-delivery/sdk/tryevent"
 	"git.novox.be/novox/mesh-sdk/go/delivery"

 	"mesh-delivery-indexer/internal/index"
@@ -73,7 +74,10 @@ func (w *previewWatch) ensure() error {
 			}
 		})
 	}()
-	return w.ix.RecomputeCandidates(w.ctx)
+	if err := w.ix.RecomputeCandidates(w.ctx); err != nil {
+		return err
+	}
+	return w.ix.WriteTryCandidates(w.ctx)
 }

 // Written takes one preview.written event of the checker in: its bucket is watched if it is not. A subject that is not the
@@ -90,3 +94,44 @@ func (w *previewWatch) Written(m delivered) {
 	}
 	_ = m.Ack()
 }
+
+// tryEventSubject is the subject of an event of the checker's stream checks about a try.
+func tryEventSubject(event string) string {
+	return "mesh.stream." + delivery.CheckerModule + ".event." + event
+}
+
+// heardChecks takes one event of the checker's stream in: a preview written (Written), or a whole try's start or end, from
+// which the candidate of its group is written or deleted (index.Indexer.StartTry, EndTry). A failure stays unacknowledged, and
+// the server delivers it again; a body that is no try event is terminated.
+func (w *previewWatch) heardChecks(m delivered) {
+	var event string
+	switch m.Subject() {
+	case tryEventSubject(tryevent.Started):
+		event = tryevent.Started
+	case tryEventSubject(tryevent.Ended):
+		event = tryevent.Ended
+	default:
+		w.Written(m)
+		return
+	}
+	e, err := tryevent.Decode(event, m.Data())
+	if err != nil {
+		w.logger.Printf("%s: not a try event, dropped: %v", m.Subject(), err)
+		_ = m.Term()
+		return
+	}
+	if event == tryevent.Started {
+		var ms []index.TryMember
+		for _, x := range e.Members {
+			ms = append(ms, index.TryMember{Repository: x.Repository, Head: x.Head, Trunk: x.Trunk})
+		}
+		err = w.ix.StartTry(w.ctx, e.ID, ms)
+	} else {
+		err = w.ix.EndTry(w.ctx, e.ID)
+	}
+	if err != nil {
+		w.logger.Printf("%s of %s: left for redelivery: %v", event, e.ID, err)
+		return
+	}
+	_ = m.Ack()
+}
@@ -16,6 +16,11 @@ type takerIn interface {
 	TakeIn(ctx context.Context, module string) index.TakenIn
 	TakeInRepository(ctx context.Context, repository string) index.TakenIn
 	JudgeAgain(ctx context.Context, module, digest string) index.TakenIn
+	TakeInPendingByHand(ctx context.Context, key, by, why string) index.TakenIn
+	DropPending(ctx context.Context, key, by, why string) index.TakenIn
+	TakeInMerge(ctx context.Context, repository, merge string, seq uint64, by, why string) index.TakenIn
+	DropTryCandidate(ctx context.Context, id, by, why string) index.TakenIn
+	RecoverTriesByHand(ctx context.Context, by, why string) index.TakenIn
 }

 // takenIn answers one value of the takeins state (the tool indexer_take_in, issue 1945): a value not yet answered takes the
@@ -34,7 +39,22 @@ func takenIn(ctx context.Context, ix takerIn, kv jetstream.KeyValue, e jetstream
 		return
 	}
 	asked, r := "take-in", index.TakenIn{}
-	if a.Repository != "" {
+	if a.RecoverTries {
+		asked, r = "recovery of the tries", ix.RecoverTriesByHand(ctx, a.By, a.Why)
+		a.Module = "tries"
+	} else if a.TryCandidate != "" && a.Drop {
+		asked, r = "drop of a try's candidate", ix.DropTryCandidate(ctx, a.TryCandidate, a.By, a.Why)
+		a.Module = a.TryCandidate
+	} else if a.Merge != "" {
+		asked, r = "hand take-in of a merge", ix.TakeInMerge(ctx, a.MergeRepository, a.Merge, a.Sequence, a.By, a.Why)
+		a.Module = r.Module
+	} else if a.Pending != "" && a.Drop {
+		asked, r = "drop of a pending merge", ix.DropPending(ctx, a.Pending, a.By, a.Why)
+		a.Module = a.Pending
+	} else if a.Pending != "" {
+		asked, r = "hand take-in of what waits", ix.TakeInPendingByHand(ctx, a.Pending, a.By, a.Why)
+		a.Module = a.Pending
+	} else if a.Repository != "" {
 		asked, r = "take-in of a repository", ix.TakeInRepository(ctx, a.Repository)
 		a.Module = a.Repository
 	} else if a.Judge {
@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"time"

+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-indexer/takein"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 	"git.novox.be/novox/mesh-sdk/go/process"
 	"github.com/nats-io/nats.go"
@@ -62,3 +63,28 @@ func sayAccepted(js jetstream.JetStream, cred process.Account, logf func(string,
 		}
 	}
 }
+
+// sayTakeIn says a take-in event (novox/hq ADR 0633 §5) as the indexer's ordinary event, on the path its other events
+// take: mesh.mod.<module>.event.take-in.<kind>, the wait's key in the body. A publish that fails is the caller's to say.
+func sayTakeIn(js jetstream.JetStream, cred process.Account) func(context.Context, takein.TakeIn) error {
+	return func(ctx context.Context, t takein.TakeIn) error {
+		event, err := takein.TakeInEvent(t.Kind)
+		if err != nil {
+			return err
+		}
+		data, err := takein.EncodeTakeIn(t)
+		if err != nil {
+			return err
+		}
+		msg := nats.NewMsg(cred.EventSubject(event))
+		msg.Header.Set("x-source", cred.Module)
+		msg.Header.Set("x-node", cred.Node)
+		msg.Header.Set("x-time", time.Now().UTC().Format(time.RFC3339Nano))
+		msg.Header.Set("content-type", "application/json")
+		msg.Data = data
+		pub, cancel := context.WithTimeout(context.WithoutCancel(ctx), 10*time.Second)
+		defer cancel()
+		_, err = js.PublishMsg(pub, msg)
+		return err
+	}
+}
@@ -46,7 +46,19 @@ func run(args []string, stdin io.Reader, stdout, stderr io.Writer) int {
 		fmt.Fprintln(stderr, "mesh-judge:", err)
 		return 1
 	}
-	v, err := judge.Request(r)
+	// The request's seat definitions (ADR 0636 §4): the composer's request type of this build does not decode them.
+	var seats struct {
+		Seats []json.RawMessage `json:"seats"`
+	}
+	if err := json.Unmarshal(raw, &seats); err != nil {
+		fmt.Fprintln(stderr, "mesh-judge:", err)
+		return 1
+	}
+	files := make([][]byte, len(seats.Seats))
+	for i, s := range seats.Seats {
+		files[i] = s
+	}
+	v, err := judge.RequestWith(r, files)
 	if err != nil {
 		fmt.Fprintln(stderr, "mesh-judge:", err)
 		return 1
@@ -3,7 +3,7 @@ module mesh-delivery-indexer
 go 1.26.0

 require (
-	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261103221822-85ba0a9a70d8
+	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261104002338-5a38a1221659
 	github.com/nats-io/nats-server/v2 v2.11.17
 	github.com/nats-io/nats.go v1.54.0
 )
@@ -24,6 +24,14 @@ require (

 replace git.novox.be/novox/mesh-delivery/modules/mesh-delivery-builder/buildrun => ../mesh-delivery-builder/buildrun

-require git.novox.be/novox/mesh-delivery/sdk v0.0.0-00010101000000-000000000000
+require (
+	git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg v0.0.0-00010101000000-000000000000
+	git.novox.be/novox/mesh-delivery/modules/mesh-delivery-indexer/takein v0.0.0-00010101000000-000000000000
+	git.novox.be/novox/mesh-delivery/sdk v0.0.0-00010101000000-000000000000
+)

 replace git.novox.be/novox/mesh-delivery/sdk => ../../sdk
+
+replace git.novox.be/novox/mesh-delivery/modules/mesh-delivery-indexer/takein => ./takein
+
+replace git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg => ../mesh-delivery-forge-bridge/forgemsg
@@ -1,5 +1,5 @@
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261103221822-85ba0a9a70d8 h1:XEbIVImp6yGjA91rp0iZBoDdL5KfamjOuDLwWvqh0hc=
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261103221822-85ba0a9a70d8/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261104002338-5a38a1221659 h1:tK7MzxVm/ECNg1Yblhh1ynVEthbZCg2mSPW0wQZC0b0=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261104002338-5a38a1221659/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op h1:Z/MZK75wC/NSrkgqeNIa7jexam9uWzhLmFTSCPI/kn0=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op/go.mod h1:FQyySiasQQM8735Ddel3MRojmy4dA1IqCeyJ5jmPMbI=
 github.com/google/go-tpm v0.9.8 h1:slArAR9Ft+1ybZu0lBwpSmpwhRXaa85hWtMinMyRAWo=
@@ -7,12 +7,13 @@ import (
 	"strings"
 	"testing"

+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 )

-func manifestPull(t *testing.T, number int, head, manifest string) delivery.Forge {
-	f := delivery.Forge{V: delivery.Version, Kind: delivery.ForgePull, Repository: catalogueRepo, Branch: "feat/x", Number: number, Head: head,
-		Action: delivery.PullUpdated, Dirs: []string{"modules/avahi"}, DirsKnown: true}
+func manifestPull(t *testing.T, number int, head, manifest string) forgemsg.Forge {
+	f := forgemsg.Forge{V: delivery.Version, Kind: forgemsg.ForgePull, Repository: catalogueRepo, Branch: "feat/x", Number: number, Head: head,
+		Action: forgemsg.PullUpdated, Dirs: []string{"modules/avahi"}, DirsKnown: true}
 	if manifest != "" {
 		f.Manifests = map[string]string{"modules/avahi": manifest}
 	}
@@ -11,6 +11,9 @@ import (
 	"sync/atomic"
 	"time"

+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-indexer/takein"
+	"git.novox.be/novox/mesh-delivery/sdk/tryevent"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 )

@@ -80,6 +83,9 @@ type Indexer struct {
 	// repository it replaces by a directory (fingerprint.ReplacedSiblings), which the version line takes by their
 	// content; nil reads none.
 	GoMod func(ctx context.Context, repository, sha, dir string) ([]byte, error)
+	// ReadFile reads one file of a repository at a commit (gitea.gitea_get_file); a file the commit does not hold is nil.
+	// With Files it reads the seat definitions a revision carries (seatsof.go); nil reads none.
+	ReadFile func(ctx context.Context, repository, sha, path string) ([]byte, error)
 	// Now is the clock of a taken value; nil is time.Now.
 	Now    func() time.Time
 	Builds *Builds
@@ -98,7 +104,7 @@ type Indexer struct {
 	// ReadOpen asks the forge which pull requests into the trunk are open now (gitea_open_pulls). A catalogue pull message
 	// that finds the candidates of another pull request asks it and deletes those of a pull request no longer open, so a
 	// closed message the indexer missed heals at the next one (issue 1126); nil asks none.
-	ReadOpen func(ctx context.Context) ([]delivery.OpenPull, error)
+	ReadOpen func(ctx context.Context) ([]forgemsg.OpenPull, error)

 	mu         sync.Mutex // guards source, toolchains and previews, which the watches and the forge messages all reach
 	source     sourceNow
@@ -106,7 +112,7 @@ type Indexer struct {
 	toolchains map[string]map[string]delivery.Toolchain         // language, then node (toolchains.go)
 	tried      map[string]bool                                  // repository, commit and directory a registered module's manifest was tried at (registered.go)
 	unread     map[string]bool                                  // registered modules whose last read the forge could not answer, read again by RetryUnread
-	moving     map[string]delivery.Forge                        // by modules key: a merge naming a module another repository holds, waiting for that trunk to drop it (moves.go)
+	moving     map[string]forgemsg.Forge                        // by modules key: a merge naming a module another repository holds, waiting for that trunk to drop it (moves.go)
 	retrying   atomic.Bool                                      // a RetryUnread runs in the background (kickRetry)
 	retryAgain atomic.Bool                                      // an event asked for one more RetryUnread after the running one
 	retryWG    sync.WaitGroup                                   // the background RetryUnread, for tests to wait on
@@ -115,12 +121,38 @@ type Indexer struct {
 	filling    atomic.Bool                                      // a FillTaken runs in the background (KickFill)
 	fillAgain  atomic.Bool                                      // a kick arrived while it ran
 	atHeads    map[string]map[string]delivery.PublishedPackages // a member head's published Go modules, by repository@head (candidatePublished)
+	saidAt     map[string]string                                // the head of a repository whose failed read was said, by repository: said once per head
+	failedAt   map[string]string                                // the head of a repository whose tree lacks a directory asked, by repository: not asked again until the head changes
 	// OwnBuild answers the fingerprint of the build this program runs, from the node-engine's seat; nil knows none.
-	OwnBuild     func(ctx context.Context) (string, error)
-	judgeMu      sync.Mutex  // one judge pass at a time (verdicts.go)
-	ownMu        sync.Mutex  // guards ownFP
-	ownFP        string      // the fingerprint of the build this program runs, asked at the start pass (learnOwnBuild)
-	judgePending atomic.Bool // the start's judge pass failed: judged again at the next message (verdicts.go)
+	OwnBuild   func(ctx context.Context) (string, error)
+	underSeats bool       // a dry run inside judge.WithSeats: its judge passes do not hold the seat list (verdicts.go)
+	judgeMu    sync.Mutex // one judge pass at a time (verdicts.go)
+	ownMu      sync.Mutex // guards ownFP
+	ownFP      string     // the fingerprint of the build this program runs, fixed once at the start (FixOwnBuild)
+	ownFixed   bool       // FixOwnBuild asked already: it asks once
+	ownSince   time.Time  // when the build was asked and not known, with ownWhy
+	ownWhy     string
+	// OwnBuildState keeps which build this process knows it runs, or since when and why not (FixOwnBuild); nil keeps none.
+	OwnBuildState Store
+	judgePending  atomic.Bool // the start's judge pass failed: judged again at the next message (verdicts.go)
+	// Message asks the forge bridge for the merged message of a merge, repository and merge commit in, the message whole out (a
+	// pending value keeps a reference, not a copy: issue 1585); an error is the bridge's words. Nil asks none.
+	Message func(ctx context.Context, repository, merge string) ([]byte, error)
+	heldMu  sync.Mutex
+	held    map[uint64]forgemsg.Forge // the merged messages Arrive was handed, by stream sequence, until their merge is taken in or dropped
+	// Pending is the state of merges held for the indexer their revision names (pending.go, novox/hq ADR 0633 §1); nil
+	// takes every merge in at once, as before the take-in step.
+	Pending Store
+	// SayTakeIn publishes a take-in event (take-in.pending, take-in.taken; ADR 0633 §5); nil says none.
+	SayTakeIn func(ctx context.Context, t takein.TakeIn) error
+	// OpenTries lists the tries that wait or run, from the checker's tool (checker_tries); nil recovers none (trycandidates.go).
+	OpenTries func(ctx context.Context) ([]tryevent.Open, error)
+	// TryRecovery keeps how the last recovery of the open tries went (trycandidates.go); nil keeps none.
+	TryRecovery    Store
+	tryMu          sync.Mutex             // one try event or recovery at a time (trycandidates.go)
+	recoveryFailed atomic.Bool            // the last recovery of the open tries failed (trycandidates.go)
+	tries          map[string][]TryMember // the whole tries that wait or run, by try id (trycandidates.go); guarded by mu
+	pendingMu      sync.Mutex             // one take-in step at a time: a merge, a group's end, the start and a hand act (pending.go)
 }

 func (ix *Indexer) logf(format string, args ...any) {
@@ -133,23 +165,23 @@ func (ix *Indexer) logf(format string, args ...any) {
 // pull request, a closed one or a merged message takes it out; a group left with none is deleted. A change is written
 // by compare-and-set on the revision read, and read again on a conflict. A lone pull request is a group of one. A
 // merged message also writes the fingerprint of each module of its repository (modules.go).
-func (ix *Indexer) Apply(ctx context.Context, f delivery.Forge) error {
+func (ix *Indexer) Apply(ctx context.Context, f forgemsg.Forge) error {
 	_, err := ix.ApplyMessage(ctx, f)
 	return err
 }

 // ApplyMessage is Apply, and answers which modules a merged message wrote and kept (for the indexer's heard state). Each
 // applied merged message is said in one line: its repository, commit and pull request, and the modules written.
-func (ix *Indexer) ApplyMessage(ctx context.Context, f delivery.Forge) (Applied, error) {
+func (ix *Indexer) ApplyMessage(ctx context.Context, f forgemsg.Forge) (Applied, error) {
 	ix.kickJudge(ctx)
 	var applied Applied
-	if f.Kind == delivery.ForgeOpen {
+	if f.Kind == forgemsg.ForgeOpen {
 		return applied, ix.applyOpen(ctx, f)
 	}
-	if f.Kind != delivery.ForgePull && f.Kind != delivery.ForgeMerged {
+	if f.Kind != forgemsg.ForgePull && f.Kind != forgemsg.ForgeMerged {
 		return applied, nil
 	}
-	if f.Kind == delivery.ForgeMerged && ix.Modules != nil {
+	if f.Kind == forgemsg.ForgeMerged && ix.Modules != nil {
 		w, err := ix.applyMerged(ctx, f)
 		applied = Applied{Written: w.written, Late: w.late}
 		if err != nil {
@@ -178,7 +210,7 @@ func (ix *Indexer) ApplyMessage(ctx context.Context, f delivery.Forge) (Applied,
 	}
 	var digests map[string]string
 	var held map[string]delivery.Module
-	if f.Kind == delivery.ForgePull {
+	if f.Kind == forgemsg.ForgePull {
 		var err error
 		if digests, err = ix.keepManifests(ctx, f); err != nil {
 			return applied, err
@@ -207,15 +239,26 @@ func (ix *Indexer) ApplyMessage(ctx context.Context, f delivery.Forge) (Applied,
 			ix.logf("%s#%d: its config declarations are not written: %v", f.Repository, f.Number, err)
 		}
 	}
+	return applied, ix.writeCandidate(ctx, f, digests, held)
+}
+
+// removeCandidate takes a merged pull request out of its group's candidate and writes nothing else of its message: for a
+// merge a newer merge of the same repository covers (it needs only the repository, number and branch).
+func (ix *Indexer) removeCandidate(ctx context.Context, f forgemsg.Forge) error {
+	return ix.writeCandidate(ctx, f, nil, nil)
+}
+
+// writeCandidate writes the group's candidate with the pull request f names (taken out for a merged or closed one).
+func (ix *Indexer) writeCandidate(ctx context.Context, f forgemsg.Forge, digests map[string]string, held map[string]delivery.Module) error {
 	if trunkLike[f.Branch] {
 		ix.logf("%s#%d: its branch %q is no delivery group, so no candidate", f.Repository, f.Number, f.Branch)
-		return applied, nil
+		return nil
 	}
 	key, err := delivery.CandidatesKey(f.Branch)
 	if err != nil {
-		return applied, fmt.Errorf("%w: %s#%d: %v", ErrUnreadable, f.Repository, f.Number, err)
+		return fmt.Errorf("%w: %s#%d: %v", ErrUnreadable, f.Repository, f.Number, err)
 	}
-	return applied, write(ctx, ix.Store, key, func(value []byte, found bool) ([]byte, bool, error) {
+	return write(ctx, ix.Store, key, func(value []byte, found bool) ([]byte, bool, error) {
 		var cur *delivery.Candidate
 		if found {
 			c, err := delivery.DecodeCandidate(value)
@@ -245,8 +288,8 @@ func (ix *Indexer) ApplyMessage(ctx context.Context, f delivery.Forge) (Applied,
 // applyOpen takes an open message into the candidates (novox/hq ADR 0443 §5): every pull request it does not name is
 // taken out of its group, and a group left with none is deleted. What the message names is left as it is. A pull request
 // opened after the bridge read the forge is heard after this message and added again by its own.
-func (ix *Indexer) applyOpen(ctx context.Context, f delivery.Forge) error {
-	named := make(map[delivery.OpenPull]bool, len(f.Open))
+func (ix *Indexer) applyOpen(ctx context.Context, f forgemsg.Forge) error {
+	named := make(map[forgemsg.OpenPull]bool, len(f.Open))
 	for _, p := range f.Open {
 		named[p] = true
 	}
@@ -255,6 +298,9 @@ func (ix *Indexer) applyOpen(ctx context.Context, f delivery.Forge) error {
 		return fmt.Errorf("listing the candidates: %w", err)
 	}
 	for _, key := range keys {
+		if IsTryGroup(key) {
+			continue // a try's candidate is no pull request's: the checker's try owns it (trycandidates.go)
+		}
 		err := write(ctx, ix.Store, key, func(value []byte, found bool) ([]byte, bool, error) {
 			if !found {
 				return nil, false, nil
@@ -264,7 +310,7 @@ func (ix *Indexer) applyOpen(ctx context.Context, f delivery.Forge) error {
 				return nil, false, fmt.Errorf("candidates.%s holds what is not a candidate: %w", key, err)
 			}
 			kept := slices.DeleteFunc(slices.Clone(c.Pulls), func(p delivery.CandidatePull) bool {
-				return !named[delivery.OpenPull{Repository: p.Repository, Number: p.Number}]
+				return !named[forgemsg.OpenPull{Repository: p.Repository, Number: p.Number}]
 			})
 			switch {
 			case len(kept) == len(c.Pulls):
@@ -331,14 +377,14 @@ func write(ctx context.Context, st Store, key string, compute func(value []byte,
 // its manifest and why it has no fingerprint of the new form (NoneNoPreview), and the candidate its FPSet (issue 1451); a
 // pull request whose head is held again without its directories keeps the Fps it had. digests are the manifests' digests by
 // directory; held are the modules the modules bucket holds, which name the module of a changed directory (moduleOfDir).
-func (ix *Indexer) next(cur *delivery.Candidate, f delivery.Forge, digests map[string]string, held map[string]delivery.Module) *delivery.Candidate {
+func (ix *Indexer) next(cur *delivery.Candidate, f forgemsg.Forge, digests map[string]string, held map[string]delivery.Module) *delivery.Candidate {
 	var pulls []delivery.CandidatePull
 	var base uint64
 	if cur != nil {
 		pulls, base = slices.Clone(cur.Pulls), cur.Base
 	}
 	at := slices.IndexFunc(pulls, func(p delivery.CandidatePull) bool { return p.Repository == f.Repository && p.Number == f.Number })
-	if f.Kind == delivery.ForgeMerged || f.Action == delivery.PullClosed {
+	if f.Kind == forgemsg.ForgeMerged || f.Action == forgemsg.PullClosed {
 		if at < 0 {
 			return cur
 		}
@@ -10,6 +10,7 @@ import (
 	"strings"
 	"time"

+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 	"git.novox.be/novox/mesh-sdk/go/process"
 )
@@ -27,7 +28,7 @@ var (

 // writePredefined keeps the predefined list a merged message carries, unless the key names a later merge: a merge older
 // than the one it names never replaces it (ADR 0348 §7). The same list at the same merge writes nothing (ADR 0289 §1).
-func (ix *Indexer) writePredefined(ctx context.Context, f delivery.Forge) error {
+func (ix *Indexer) writePredefined(ctx context.Context, f forgemsg.Forge) error {
 	if ix.Predefined == nil || len(f.Predefined) == 0 {
 		return nil
 	}
@@ -203,8 +204,8 @@ func (ix *Indexer) dropConfigCandidate(ctx context.Context, repository string, n

 // configCandidateOfPull is a pull message's part in config-candidates: a head whose manifests the message carries is written,
 // a closed one deleted. A head held again without its directories leaves the key as it is.
-func (ix *Indexer) configCandidateOfPull(ctx context.Context, f delivery.Forge, held map[string]delivery.Module) error {
-	if f.Action == delivery.PullClosed {
+func (ix *Indexer) configCandidateOfPull(ctx context.Context, f forgemsg.Forge, held map[string]delivery.Module) error {
+	if f.Action == forgemsg.PullClosed {
 		return ix.dropConfigCandidate(ctx, f.Repository, f.Number)
 	}
 	if !f.DirsKnown {
@@ -220,7 +221,7 @@ func (ix *Indexer) configCandidateOfPull(ctx context.Context, f delivery.Forge,
 // configCandidatesAfterMerge writes again every open pull request's key that names a module the merge changed, since what
 // it adds is judged against the trunk (ADR 0565 §2), from the head's manifests its candidate keeps; and deletes the merged
 // pull request's.
-func (ix *Indexer) configCandidatesAfterMerge(ctx context.Context, f delivery.Forge, changed []string) error {
+func (ix *Indexer) configCandidatesAfterMerge(ctx context.Context, f forgemsg.Forge, changed []string) error {
 	if ix.ConfigCandidates == nil {
 		return nil
 	}
@@ -243,6 +244,9 @@ func (ix *Indexer) configCandidatesAfterMerge(ctx context.Context, f delivery.Fo
 	}
 	var errs []error
 	for _, g := range groups {
+		if IsTryGroup(g) {
+			continue // a try's candidate holds no pull request's config declarations (trycandidates.go)
+		}
 		raw, _, found, err := ix.Store.Get(ctx, g)
 		if err != nil || !found {
 			continue
@@ -7,6 +7,7 @@ import (
 	"testing"
 	"time"

+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 	"git.novox.be/novox/mesh-sdk/go/process"
 )
@@ -77,12 +78,29 @@ func TestTheControlRecords(t *testing.T) {
 			t.Errorf("a head declaring nothing new = %+v, want an empty set", c)
 		}
 		closed := pull(catalogueRepo, 7, "feat/y", strings.Repeat("d", 40))
-		closed.Action = delivery.PullClosed
+		closed.Action = forgemsg.PullClosed
 		if err := ix.Apply(ctx, closed); err != nil {
 			t.Fatal(err)
 		}
 		if _, ok := cands.vals[key]; ok {
 			t.Error("a closed pull request's declarations stayed")
 		}
+		// A group try's candidate (number 0) holds no pull request's declarations: a merge that touches its module writes none
+		// for it (fails when configCandidatesAfterMerge no longer skips a try's group).
+		tryPull := delivery.CandidatePull{Head: delivery.Head{Repository: catalogueRepo, Head: h1}, Modules: []string{"avahi"},
+			Fps: map[string]delivery.CandidateModule{"avahi": {Manifest: delivery.ManifestDigest([]byte(trunk)), None2: NoneNoPreview}}}
+		tryCand := delivery.Candidate{V: delivery.Version, Group: "try-5", Pulls: []delivery.CandidatePull{tryPull}}
+		tryCand.HeadsHash, _ = delivery.HeadsHash([]delivery.Head{tryPull.Head})
+		tryCand.FPSet = delivery.FingerprintSet(tryCand.Pulls)
+		data, err := delivery.EncodeCandidate(tryCand)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if err := ix.Store.Create(ctx, "try-5", data); err != nil {
+			t.Fatal(err)
+		}
+		if err := ix.configCandidatesAfterMerge(ctx, mergedMsg(catalogueRepo, map[string]string{"modules/avahi": "t2"}), []string{"avahi"}); err != nil || len(cands.vals) != 0 {
+			t.Errorf("a merge touching a try's module wrote %v for it (%v), want none", cands.vals, err)
+		}
 	})
 }
@@ -2,9 +2,11 @@ package index

 import (
 	"context"
+	"errors"
 	"strings"
 	"testing"

+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 )

@@ -25,6 +27,16 @@ type memStore struct {
 	next        uint64
 	writes      int
 	beforeWrite func()
+	failWrite   func(key string) error // a write's own error, asked before each Create and Update
+	maxValue    int                    // the bucket's value cap (buscompose.StateMaxValueBytes); a larger value is refused as the bus refuses it
+}
+
+// tooBig is the bus's refusal of a value over a bucket's cap.
+func (m *memStore) tooBig(value []byte) error {
+	if m.maxValue > 0 && len(value) > m.maxValue {
+		return errors.New("nats: API error: code=400 err_code=10054 description=message size exceeds maximum allowed")
+	}
+	return nil
 }

 func newMem() *memStore { return &memStore{vals: map[string][]byte{}, revs: map[string]uint64{}} }
@@ -58,18 +70,34 @@ func (m *memStore) put(key string, value []byte) {
 }
 func (m *memStore) Create(_ context.Context, key string, value []byte) error {
 	m.hook()
+	if f := m.failWrite; f != nil {
+		if err := f(key); err != nil {
+			return err
+		}
+	}
 	if _, ok := m.vals[key]; ok {
 		return ErrConflict
 	}
+	if err := m.tooBig(value); err != nil {
+		return err
+	}
 	m.writes++
 	m.put(key, value)
 	return nil
 }
 func (m *memStore) Update(_ context.Context, key string, value []byte, rev uint64) error {
 	m.hook()
+	if f := m.failWrite; f != nil {
+		if err := f(key); err != nil {
+			return err
+		}
+	}
 	if _, ok := m.vals[key]; !ok || m.revs[key] != rev {
 		return ErrConflict
 	}
+	if err := m.tooBig(value); err != nil {
+		return err
+	}
 	m.writes++
 	m.put(key, value)
 	return nil
@@ -91,9 +119,9 @@ func buildRecord(t *testing.T, repo, module, path, at string) []byte {
 	return logged(t, "build-"+module, module, repo, path, "", "", at)
 }

-func pull(repo string, number int, branch, head string, dirs ...string) delivery.Forge {
-	return delivery.Forge{V: delivery.Version, Kind: delivery.ForgePull, Repository: repo, Branch: branch, Number: number, Head: head,
-		Action: delivery.PullUpdated, Dirs: dirs, DirsKnown: dirs != nil}
+func pull(repo string, number int, branch, head string, dirs ...string) forgemsg.Forge {
+	return forgemsg.Forge{V: delivery.Version, Kind: forgemsg.ForgePull, Repository: repo, Branch: branch, Number: number, Head: head,
+		Action: forgemsg.PullUpdated, Dirs: dirs, DirsKnown: dirs != nil}
 }

 func newIndexer(t *testing.T) (*Indexer, *memStore, *strings.Builder) {
@@ -212,13 +240,13 @@ func TestClosedAndMergedTakeAPullOutAndTheLastDeletesTheKey(t *testing.T) { // 1
 		ctx := context.Background()
 		_ = ix.Apply(ctx, pull("novox/mesh-delivery", 12, "feat/x", h1, "modules/a"))
 		_ = ix.Apply(ctx, pull("novox/mesh-catalog", 300, "feat/x", h2, "modules/c"))
-		gone := func(repo string, n int, head string) delivery.Forge {
+		gone := func(repo string, n int, head string) forgemsg.Forge {
 			if how == "closed" {
 				f := pull(repo, n, "feat/x", head)
-				f.Action = delivery.PullClosed
+				f.Action = forgemsg.PullClosed
 				return f
 			}
-			return delivery.Forge{V: delivery.Version, Kind: delivery.ForgeMerged, Repository: repo, Branch: "feat/x", Number: n, Head: head, Merge: h3, Root: "r", Trees: map[string]string{"a": "t"}}
+			return forgemsg.Forge{V: delivery.Version, Kind: forgemsg.ForgeMerged, Repository: repo, Branch: "feat/x", Number: n, Head: head, Merge: h3, Root: "r", Trees: map[string]string{"a": "t"}}
 		}
 		if err := ix.Apply(ctx, gone("novox/mesh-delivery", 12, h1)); err != nil {
 			t.Fatal(err)
@@ -330,8 +358,8 @@ func TestAnOddBranchNameKeysEscaped(t *testing.T) {
 	}
 }

-func open(pulls ...delivery.OpenPull) delivery.Forge {
-	return delivery.Forge{V: delivery.Version, Kind: delivery.ForgeOpen, Open: pulls}
+func open(pulls ...forgemsg.OpenPull) forgemsg.Forge {
+	return forgemsg.Forge{V: delivery.Version, Kind: forgemsg.ForgeOpen, Open: pulls}
 }

 // 1279/AC7 (ADR 0443 §5): on an open message, candidates lose every pull request it does not name, a group left empty is
@@ -339,7 +367,7 @@ func open(pulls ...delivery.OpenPull) delivery.Forge {
 func TestAnOpenMessageDropsEveryCandidateItDoesNotName(t *testing.T) { // 1279/AC7
 	ix, st, _ := newIndexer(t)
 	ctx := context.Background()
-	for _, f := range []delivery.Forge{
+	for _, f := range []forgemsg.Forge{
 		pull("novox/mesh-delivery", 12, "feat/x", h1, "modules/a"), pull("novox/mesh-catalog", 300, "feat/x", h2, "modules/c"),
 		pull("novox/mesh-delivery", 13, "feat/y", h2, "modules/a"),
 		pull("novox/mesh-catalog", 280, "feat/old", h3, "modules/c"),
@@ -351,7 +379,7 @@ func TestAnOpenMessageDropsEveryCandidateItDoesNotName(t *testing.T) { // 1279/A
 	before, _ := read(t, st, "feat/x")

 	// Open: mesh-delivery#12 only (and a pull request no group holds, which changes nothing).
-	if err := ix.Apply(ctx, open(delivery.OpenPull{Repository: "novox/mesh-delivery", Number: 12}, delivery.OpenPull{Repository: "novox/mesh-catalog", Number: 999})); err != nil {
+	if err := ix.Apply(ctx, open(forgemsg.OpenPull{Repository: "novox/mesh-delivery", Number: 12}, forgemsg.OpenPull{Repository: "novox/mesh-catalog", Number: 999})); err != nil {
 		t.Fatal(err)
 	}
 	c, ok := read(t, st, "feat/x")
@@ -374,7 +402,7 @@ func TestAnOpenMessageDropsEveryCandidateItDoesNotName(t *testing.T) { // 1279/A
 	}
 	// The same open message again changes nothing (no write), and an empty one drops every group.
 	writes := st.writes
-	if err := ix.Apply(ctx, open(delivery.OpenPull{Repository: "novox/mesh-delivery", Number: 12}, delivery.OpenPull{Repository: "novox/mesh-catalog", Number: 300})); err != nil {
+	if err := ix.Apply(ctx, open(forgemsg.OpenPull{Repository: "novox/mesh-delivery", Number: 12}, forgemsg.OpenPull{Repository: "novox/mesh-catalog", Number: 300})); err != nil {
 		t.Fatal(err)
 	}
 	if st.writes != writes {
@@ -5,6 +5,7 @@ import (
 	"errors"
 	"fmt"

+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 )

@@ -48,7 +49,7 @@ func (ix *Indexer) keepManifest(ctx context.Context, module, raw string) (string

 // keepManifests writes the manifest of each directory a message carries, and answers the digest of each by directory.
 // A manifest that cannot be kept is left out and said in the log, so the module reads as one with no manifest.
-func (ix *Indexer) keepManifests(ctx context.Context, f delivery.Forge) (map[string]string, error) {
+func (ix *Indexer) keepManifests(ctx context.Context, f forgemsg.Forge) (map[string]string, error) {
 	digests := make(map[string]string, len(f.Manifests))
 	for dir, raw := range f.Manifests {
 		module := manifestModule(raw) // the name the manifest gives itself: one digest always has one module
@@ -5,6 +5,7 @@ import (
 	"os"
 	"testing"

+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 )

@@ -37,7 +38,7 @@ func manifestsIndexer(t *testing.T, recs ...[2]any) (*Indexer, *memStore, *memSt
 	return ix, mods, manifests
 }

-func withManifests(f delivery.Forge, manifests map[string]string, locks map[string]map[string]string) delivery.Forge {
+func withManifests(f forgemsg.Forge, manifests map[string]string, locks map[string]map[string]string) forgemsg.Forge {
 	f.Manifests, f.Locks = manifests, locks
 	return f
 }
@@ -81,8 +82,8 @@ func sameManifestAppliedAgainIsWrittenOnce(t *testing.T) { // 1449/AC2
 	if err := ix.Apply(context.Background(), f); err != nil {
 		t.Errorf("a second merge: %v", err)
 	}
-	pull := delivery.Forge{V: delivery.Version, Kind: delivery.ForgePull, Repository: catalogueRepo, Branch: "feat/x", Number: 301, Head: h1,
-		Action: delivery.PullUpdated, Dirs: []string{"modules/avahi"}, DirsKnown: true, Manifests: map[string]string{"modules/avahi": avahi}}
+	pull := forgemsg.Forge{V: delivery.Version, Kind: forgemsg.ForgePull, Repository: catalogueRepo, Branch: "feat/x", Number: 301, Head: h1,
+		Action: forgemsg.PullUpdated, Dirs: []string{"modules/avahi"}, DirsKnown: true, Manifests: map[string]string{"modules/avahi": avahi}}
 	if err := ix.Apply(context.Background(), pull); err != nil {
 		t.Errorf("a pull message: %v", err)
 	}
@@ -7,6 +7,7 @@ import (
 	"slices"
 	"strings"

+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 	"git.novox.be/novox/mesh-sdk/go/catalogue"
 	"git.novox.be/novox/mesh-sdk/go/delivery"

@@ -31,20 +32,20 @@ import (
 //
 // A merge never moves a module backwards (order.go): a merged message older than the repository's taken merge writes and
 // deletes nothing, and is said; it is asked once, before anything is written.
-func (ix *Indexer) applyMerged(ctx context.Context, f delivery.Forge) (*mergeWrite, error) {
+func (ix *Indexer) applyMerged(ctx context.Context, f forgemsg.Forge) (*mergeWrite, error) {
 	return ix.applyManifests(ctx, f, true)
 }

 // applyManifests is applyMerged; drop says whether the modules of the repository the message holds no manifest for are
 // deleted. A message that names only some of a repository's modules (a registered module read on its own, registered.go)
 // drops none.
-func (ix *Indexer) applyManifests(ctx context.Context, f delivery.Forge, drop bool) (*mergeWrite, error) {
+func (ix *Indexer) applyManifests(ctx context.Context, f forgemsg.Forge, drop bool) (*mergeWrite, error) {
 	return ix.applyMoving(ctx, f, drop, nil)
 }

 // applyMoving is applyManifests; moves names the modules keys the message may take from the repository that holds them
 // (a move handed over, moves.go). Every other module held of another repository is left, said and kept waiting.
-func (ix *Indexer) applyMoving(ctx context.Context, f delivery.Forge, drop bool, moves map[string]bool) (*mergeWrite, error) {
+func (ix *Indexer) applyMoving(ctx context.Context, f forgemsg.Forge, drop bool, moves map[string]bool) (*mergeWrite, error) {
 	w := newMergeWrite(f)
 	if drop {
 		if err := ix.lateMerge(ctx, w); err != nil || w.late != "" {
@@ -180,7 +181,7 @@ func withV(m delivery.Module) delivery.Module { m.V = delivery.Version; return m
 // namedObjects are, by module directory, the git objects of the paths each manifest of the merge names for every artifact
 // (catalogue Manifest.NamedPaths): those the message carries, else asked of the forge at the merge commit in one call
 // (Named). A forge that cannot say gives, for each directory asked, its words, so the module's reason names them.
-func (ix *Indexer) namedObjects(ctx context.Context, f delivery.Forge) (map[string]map[string]string, map[string]string) {
+func (ix *Indexer) namedObjects(ctx context.Context, f forgemsg.Forge) (map[string]map[string]string, map[string]string) {
 	objects := map[string]map[string]string{}
 	need := map[string][]string{}
 	for dir, raw := range f.Manifests {
@@ -220,7 +221,7 @@ func (ix *Indexer) namedObjects(ctx context.Context, f delivery.Forge) (map[stri
 // held(key, module) says whether the trunk holds it. A module of another repository, or of none known, is never touched.
 func (ix *Indexer) dropRemoved(ctx context.Context, repository string, held map[string]delivery.Module, trunkHolds func(key string, m delivery.Module) bool) error {
 	var handed []string
-	elsewhere := map[string]delivery.Forge{}
+	elsewhere := map[string]forgemsg.Forge{}
 	for _, key := range slices.Sorted(maps.Keys(held)) {
 		cur := held[key]
 		if cur.Repository == "" || !delivery.SameRepository(cur.Repository, repository) || trunkHolds(key, cur) {
@@ -354,7 +355,7 @@ func unreadInputs(tree string, locks, paths map[string]string, packages []string
 // goSumPackages are the version line's packages of the merge's directory dir (ADR 0573 §2, ADR 0593 §2): the mesh Go
 // modules of other repositories its go.sum names, and those of its own repository its go.mod replaces by a directory
 // (siblingPackages), which no go.sum line names. A directory with no go.sum is no Go module and has none.
-func (ix *Indexer) goSumPackages(ctx context.Context, f delivery.Forge, dir string, cur delivery.Module, has bool) []string {
+func (ix *Indexer) goSumPackages(ctx context.Context, f forgemsg.Forge, dir string, cur delivery.Module, has bool) []string {
 	others := ix.otherPackages(ctx, f, dir, cur, has)
 	if f.Locks[dir]["go.sum"] == "" && len(f.Packages[dir]) == 0 {
 		return others
@@ -368,7 +369,7 @@ func (ix *Indexer) goSumPackages(ctx context.Context, f delivery.Forge, dir stri

 // siblingPackages are the mesh Go modules of the merge's own repository the go.mod of dir replaces by a directory, read
 // from the forge (GoMod); where it cannot be read, the held module's own-repository packages stand, said.
-func (ix *Indexer) siblingPackages(ctx context.Context, f delivery.Forge, dir string, cur delivery.Module, has bool) []string {
+func (ix *Indexer) siblingPackages(ctx context.Context, f forgemsg.Forge, dir string, cur delivery.Module, has bool) []string {
 	held := func() []string {
 		if !has || cur.Inputs2 == nil {
 			return nil
@@ -395,7 +396,7 @@ func (ix *Indexer) siblingPackages(ctx context.Context, f delivery.Forge, dir st
 // otherPackages are the mesh Go modules of other repositories the go.sum of the merge's directory dir names: those the
 // message carries (an older bridge), else the held module's while its go.sum's hash is unchanged, else the go.sum read
 // from the forge (GoSum).
-func (ix *Indexer) otherPackages(ctx context.Context, f delivery.Forge, dir string, cur delivery.Module, has bool) []string {
+func (ix *Indexer) otherPackages(ctx context.Context, f forgemsg.Forge, dir string, cur delivery.Module, has bool) []string {
 	if carried := f.Packages[dir]; len(carried) > 0 {
 		return fingerprint.OtherPackages(carried, f.Repository) // its own repository's come with its tree
 	}
@@ -10,6 +10,7 @@ import (
 	"testing"
 	"time"

+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 	"git.novox.be/novox/mesh-sdk/go/catalogue"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 	"git.novox.be/novox/mesh-sdk/go/process"
@@ -71,12 +72,12 @@ func rec(t *testing.T, id, module, repo, path, ref, state, at, inputs string) [2
 // mergedMsg is a merged message of the repository with these module directories' trees, each with a manifest naming its
 // module, the directory's last element ("r" for the root), as the forge bridge sends it (one manifest per directory that
 // holds a module.json).
-func mergedMsg(repo string, trees map[string]string) delivery.Forge {
+func mergedMsg(repo string, trees map[string]string) forgemsg.Forge {
 	manifests := map[string]string{}
 	for dir := range trees {
 		manifests[dir] = `{"module":"` + nameOfDir(dir) + `","version":"1"}`
 	}
-	return delivery.Forge{V: delivery.Version, Kind: delivery.ForgeMerged, Repository: repo, Branch: "feat/x", Number: 12, Head: h1, Merge: merge, Root: "r0", Trees: trees, Manifests: manifests}
+	return forgemsg.Forge{V: delivery.Version, Kind: forgemsg.ForgeMerged, Repository: repo, Branch: "feat/x", Number: 12, Head: h1, Merge: merge, Root: "r0", Trees: trees, Manifests: manifests}
 }

 func nameOfDir(dir string) string {
@@ -459,7 +460,7 @@ func TestAModuleMovesBetweenRepositoriesOnlyWhenItsTrunkDropsIt(t *testing.T) {
 	gone.Trees, gone.Manifests = nil, nil
 	for _, tc := range []struct {
 		name        string
-		merges      []delivery.Forge
+		merges      []forgemsg.Forge
 		repository  string // modules.a's repository at the end, "" for none
 		deletedKeyA bool
 		// Issue 1367: a fresh indexer, no wait in memory, the source naming heads; trunk is the module directories the forge
@@ -472,20 +473,20 @@ func TestAModuleMovesBetweenRepositoriesOnlyWhenItsTrunkDropsIt(t *testing.T) {
 		stored     bool
 		bGoneAtEnd bool
 	}{
-		{name: "named while its trunk holds it: left", merges: []delivery.Forge{held, named}, repository: from},
-		{name: "named, then dropped by its trunk: handed over in place", merges: []delivery.Forge{held, named, dropped}, repository: to},
-		{name: "dropped by its trunk, then named: deleted, then written new", merges: []delivery.Forge{held, dropped, named}, repository: to, deletedKeyA: true},
-		{name: "dropped by its trunk with no merge naming it: deleted", merges: []delivery.Forge{held, dropped}, deletedKeyA: true},
+		{name: "named while its trunk holds it: left", merges: []forgemsg.Forge{held, named}, repository: from},
+		{name: "named, then dropped by its trunk: handed over in place", merges: []forgemsg.Forge{held, named, dropped}, repository: to},
+		{name: "dropped by its trunk, then named: deleted, then written new", merges: []forgemsg.Forge{held, dropped, named}, repository: to, deletedKeyA: true},
+		{name: "dropped by its trunk with no merge naming it: deleted", merges: []forgemsg.Forge{held, dropped}, deletedKeyA: true},
 		{name: "no module.json left, another trunk holds it, nothing waits in memory: written from that trunk, never deleted",
-			merges: []delivery.Forge{held, gone}, heads: true, trunk: []string{"modules/a", "modules/other"}, repository: to, bGoneAtEnd: true},
+			merges: []forgemsg.Forge{held, gone}, heads: true, trunk: []string{"modules/a", "modules/other"}, repository: to, bGoneAtEnd: true},
 		{name: "no module.json left, no other trunk holds it: deleted",
-			merges: []delivery.Forge{held, gone}, heads: true, deletedKeyA: true, bGoneAtEnd: true},
+			merges: []forgemsg.Forge{held, gone}, heads: true, deletedKeyA: true, bGoneAtEnd: true},
 		{name: "taken in by repository, a head with no module.json: handed over from the other trunk",
-			merges: []delivery.Forge{held}, heads: true, trunk: []string{"modules/a"}, takeIn: from, answer: "handed over", stored: true, repository: to, bGoneAtEnd: true},
+			merges: []forgemsg.Forge{held}, heads: true, trunk: []string{"modules/a"}, takeIn: from, answer: "handed over", stored: true, repository: to, bGoneAtEnd: true},
 		{name: "taken in by repository, a head with modules: answered by name",
-			merges: []delivery.Forge{held}, heads: true, trunk: []string{"modules/a"}, takeIn: to, answer: "by name", repository: from},
+			merges: []forgemsg.Forge{held}, heads: true, trunk: []string{"modules/a"}, takeIn: to, answer: "by name", repository: from},
 		{name: "taken in by repository, no head named: answered so",
-			merges: []delivery.Forge{held}, heads: true, takeIn: "novox/nobody", answer: "names no head", repository: from},
+			merges: []forgemsg.Forge{held}, heads: true, takeIn: "novox/nobody", answer: "names no head", repository: from},
 	} {
 		t.Run(tc.name, func(t *testing.T) {
 			mods := &deletesSeen{memStore: newMem()}
@@ -7,6 +7,7 @@ import (
 	"slices"
 	"strings"

+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 )

@@ -14,9 +15,9 @@ import (
 // holds it at the head the latest source names: the module directories there are asked of the forge (Trunk) and the manifest of
 // each directory named like the module is read (Read). It answers the merge to hand the module over with, or none: a forge
 // that cannot say leaves the module to be dropped as it was, said (issue 1367).
-func (ix *Indexer) heldByAnotherTrunk(ctx context.Context, module, repository string) (delivery.Forge, bool) {
+func (ix *Indexer) heldByAnotherTrunk(ctx context.Context, module, repository string) (forgemsg.Forge, bool) {
 	if ix.Trunk == nil || ix.Read == nil {
-		return delivery.Forge{}, false
+		return forgemsg.Forge{}, false
 	}
 	ix.mu.Lock()
 	heads := maps.Clone(ix.source.heads)
@@ -45,7 +46,7 @@ func (ix *Indexer) heldByAnotherTrunk(ctx context.Context, module, repository st
 			if read.Trees[dir] == "" || manifestModule(raw) != module {
 				continue
 			}
-			f := delivery.Forge{V: delivery.Version, Kind: delivery.ForgeMerged, Repository: other, Merge: head, Root: read.Root,
+			f := forgemsg.Forge{V: delivery.Version, Kind: forgemsg.ForgeMerged, Repository: other, Merge: head, Root: read.Root,
 				Trees: map[string]string{dir: read.Trees[dir]}, Manifests: map[string]string{dir: raw}}
 			if l := read.Locks[dir]; len(l) > 0 {
 				f.Locks = map[string]map[string]string{dir: l}
@@ -57,7 +58,7 @@ func (ix *Indexer) heldByAnotherTrunk(ctx context.Context, module, repository st
 			return f, true
 		}
 	}
-	return delivery.Forge{}, false
+	return forgemsg.Forge{}, false
 }

 // nameOfDirectory is the last element of a module directory.
@@ -76,8 +77,8 @@ func nameOfDirectory(dir string) string { return dir[strings.LastIndex(dir, "/")

 // waitToMove keeps, by modules key, the part of a merged message naming one module directory the indexer holds of another
 // repository. A later merge of the same repository replaces it.
-func (ix *Indexer) waitToMove(key string, f delivery.Forge, dir string) {
-	one := delivery.Forge{V: f.V, Kind: f.Kind, Repository: f.Repository, Branch: f.Branch, Number: f.Number, Merge: f.Merge, Root: f.Root,
+func (ix *Indexer) waitToMove(key string, f forgemsg.Forge, dir string) {
+	one := forgemsg.Forge{V: f.V, Kind: f.Kind, Repository: f.Repository, Branch: f.Branch, Number: f.Number, Merge: f.Merge, Root: f.Root,
 		Trees: map[string]string{dir: f.Trees[dir]}, Manifests: map[string]string{dir: f.Manifests[dir]}}
 	if l := f.Locks[dir]; len(l) > 0 {
 		one.Locks = map[string]map[string]string{dir: l}
@@ -91,7 +92,7 @@ func (ix *Indexer) waitToMove(key string, f delivery.Forge, dir string) {
 	ix.mu.Lock()
 	defer ix.mu.Unlock()
 	if ix.moving == nil {
-		ix.moving = map[string]delivery.Forge{}
+		ix.moving = map[string]forgemsg.Forge{}
 	}
 	ix.moving[key] = one
 }
@@ -117,7 +118,7 @@ func (ix *Indexer) handOver(ctx context.Context, key string) error {
 }

 // handOverFrom writes the module at key from the merge f, which names it, in place.
-func (ix *Indexer) handOverFrom(ctx context.Context, key string, f delivery.Forge) error {
+func (ix *Indexer) handOverFrom(ctx context.Context, key string, f forgemsg.Forge) error {
 	w, err := ix.applyMoving(ctx, f, false, map[string]bool{key: true})
 	if err != nil {
 		return fmt.Errorf("modules.%s, moving to %s: %w", key, f.Repository, err)
@@ -7,6 +7,7 @@ import (
 	"slices"
 	"strings"

+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 	"git.novox.be/novox/mesh-sdk/go/process"
 )
@@ -46,7 +47,7 @@ func (w *mergeWrite) taken(digest string) {
 	w.fresh[digest] = true
 }

-func newMergeWrite(f delivery.Forge) *mergeWrite {
+func newMergeWrite(f forgemsg.Forge) *mergeWrite {
 	return &mergeWrite{repository: f.Repository, merge: f.Merge}
 }

@@ -0,0 +1,110 @@
+package index
+
+import (
+	"context"
+	"maps"
+	"slices"
+	"sync"
+)
+
+// overlayStore is a store whose writes stay in memory over the store it reads through (novox/hq ADR 0633 §1): a merge
+// applied to it is computed whole, its every fingerprint and verdict, and nothing reaches the bus. A key it wrote reads
+// as written, a key it deleted as absent, every other as the store under it holds it. Its compare-and-set holds against
+// what it reads: a key it wrote has a revision of its own, counted above every revision under it. A nil store under
+// it holds nothing.
+type overlayStore struct {
+	under Store
+	mu    sync.Mutex
+	vals  map[string]overlaid
+	next  uint64
+}
+
+type overlaid struct {
+	value    []byte
+	revision uint64
+	deleted  bool
+}
+
+func newOverlay(under Store) *overlayStore {
+	return &overlayStore{under: under, vals: map[string]overlaid{}, next: 1 << 62}
+}
+
+func (o *overlayStore) Get(ctx context.Context, key string) ([]byte, uint64, bool, error) {
+	o.mu.Lock()
+	v, ok := o.vals[key]
+	o.mu.Unlock()
+	if ok {
+		if v.deleted {
+			return nil, v.revision, false, nil
+		}
+		return slices.Clone(v.value), v.revision, true, nil
+	}
+	if o.under == nil {
+		return nil, 0, false, nil
+	}
+	return o.under.Get(ctx, key)
+}
+
+// put checks the revision read against what the key holds now and writes it.
+func (o *overlayStore) put(ctx context.Context, key string, value []byte, revision uint64, create, del bool) error {
+	_, rev, found, err := o.Get(ctx, key)
+	if err != nil {
+		return err
+	}
+	o.mu.Lock()
+	defer o.mu.Unlock()
+	switch {
+	case create && found, !create && (!found || rev != revision):
+		return ErrConflict
+	}
+	o.next++
+	o.vals[key] = overlaid{value: slices.Clone(value), revision: o.next, deleted: del}
+	return nil
+}
+
+func (o *overlayStore) Create(ctx context.Context, key string, value []byte) error {
+	return o.put(ctx, key, value, 0, true, false)
+}
+
+func (o *overlayStore) Update(ctx context.Context, key string, value []byte, revision uint64) error {
+	return o.put(ctx, key, value, revision, false, false)
+}
+
+func (o *overlayStore) Delete(ctx context.Context, key string, revision uint64) error {
+	return o.put(ctx, key, nil, revision, false, true)
+}
+
+func (o *overlayStore) Keys(ctx context.Context) ([]string, error) {
+	var keys []string
+	if o.under != nil {
+		var err error
+		if keys, err = o.under.Keys(ctx); err != nil {
+			return nil, err
+		}
+	}
+	o.mu.Lock()
+	defer o.mu.Unlock()
+	keys = slices.DeleteFunc(keys, func(k string) bool { _, ok := o.vals[k]; return ok })
+	for k, v := range o.vals {
+		if !v.deleted {
+			keys = append(keys, k)
+		}
+	}
+	slices.Sort(keys)
+	return keys, nil
+}
+
+// written is what the overlay holds of key: its value, and whether it wrote or deleted it at all.
+func (o *overlayStore) written(key string) (value []byte, deleted, ok bool) {
+	o.mu.Lock()
+	defer o.mu.Unlock()
+	v, ok := o.vals[key]
+	return slices.Clone(v.value), v.deleted, ok
+}
+
+// changed is every key the overlay wrote or deleted, in order.
+func (o *overlayStore) changed() []string {
+	o.mu.Lock()
+	defer o.mu.Unlock()
+	return slices.Sorted(maps.Keys(o.vals))
+}
@@ -7,6 +7,7 @@ import (
 	"path"
 	"strings"

+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 )

@@ -70,7 +71,7 @@ func moduleAt(held map[string]delivery.Module, repository, dir string) (string,
 // moduleOfDir is the module of a changed directory of a pull request: the module its manifest in the message names, else
 // the one the modules bucket holds at that directory of the repository, else the directory's last element (the
 // catalogue's rule for nearly every manifest).
-func moduleOfDir(held map[string]delivery.Module, f delivery.Forge, dir string) string {
+func moduleOfDir(held map[string]delivery.Module, f forgemsg.Forge, dir string) string {
 	if name := manifestModule(f.Manifests[dir]); name != "" {
 		return name
 	}
@@ -2,6 +2,7 @@ package index

 import (
 	"context"
+	"errors"
 	"fmt"
 	"maps"
 	"path"
@@ -297,6 +298,12 @@ func (ix *Indexer) candidatePublished(ctx context.Context, members map[string]st
 		ix.mu.Lock()
 		got, ok := ix.atHeads[at]
 		ix.mu.Unlock()
+		ix.mu.Lock()
+		failed := ix.failedAt[repo] == head
+		ix.mu.Unlock()
+		if failed {
+			continue // said once for this head; the candidate takes the published version until the head changes
+		}
 		if !ok {
 			var ms []string
 			ms = append(ms, modules[repo]...)
@@ -307,10 +314,29 @@ func (ix *Indexer) candidatePublished(ctx context.Context, members map[string]st
 			}
 			var err error
 			if got, err = ix.packagesAt(ctx, repo, head, ms, imports[repo]); err != nil {
-				ix.logf("%s at the head %s: its packages are not read, so the candidate takes their published version: %v", repo, head, err)
+				// A failure of the tree itself (the directory is not in the tree at that head) no retry changes: it is asked once per
+				// head. Any other failure may be transient: it is asked again at the next pass, and said once per head.
+				ix.mu.Lock()
+				said := ix.saidAt[repo] == head
+				if ix.saidAt == nil {
+					ix.saidAt = map[string]string{}
+				}
+				ix.saidAt[repo] = head
+				if errors.Is(err, ErrNotInTree) {
+					if ix.failedAt == nil {
+						ix.failedAt = map[string]string{}
+					}
+					ix.failedAt[repo] = head
+				}
+				ix.mu.Unlock()
+				if !said {
+					ix.logf("%s at the head %s: its packages are not read, so the candidate takes their published version: %v", repo, head, err)
+				}
 				continue
 			}
 			ix.mu.Lock()
+			delete(ix.failedAt, repo)
+			delete(ix.saidAt, repo)
 			if ix.atHeads == nil || len(ix.atHeads) >= maxHeadsKept {
 				ix.atHeads = map[string]map[string]delivery.PublishedPackages{}
 			}
@@ -322,5 +348,9 @@ func (ix *Indexer) candidatePublished(ctx context.Context, members map[string]st
 	return out
 }

+// ErrNotInTree is a failure of the tree itself: a directory asked of the forge is not in the tree at that commit. No retry
+// changes it, so a head that fails so is asked once (candidatePublished).
+var ErrNotInTree = errors.New("the directory is not in the tree at that commit")
+
 // maxHeadsKept bounds the member heads' packages kept between recomputes; past it they are read again.
 const maxHeadsKept = 64
@@ -0,0 +1,651 @@
+package index
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"reflect"
+	"slices"
+	"strings"
+	"testing"
+
+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-indexer/takein"
+	"git.novox.be/novox/mesh-sdk/go/buscompose"
+	"git.novox.be/novox/mesh-sdk/go/catalogue"
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+	"git.novox.be/novox/mesh-sdk/go/process"
+)
+
+// takeInBed is an indexer holding the catalogue's avahi and the indexer's own module, both with a fingerprint, its
+// pending state and the take-in events it says; base is the catalogue merge it was built from.
+type takeInBed struct {
+	ix      *Indexer
+	mods    *memStore
+	pending *memStore
+	said    []takein.TakeIn
+	bridge  map[string][]byte // what the forge bridge answers (bridge_merged_message), by repository@merge
+	base    forgemsg.Forge
+	logs    *strings.Builder
+}
+
+func newTakeInBed(t *testing.T) *takeInBed {
+	t.Helper()
+	ix, mods, f := newFormIndexerUnmerged(t, mod{"avahi", catalogueManifest(t, "avahi")},
+		mod{delivery.IndexerModule, renamed(t, "avahi", delivery.IndexerModule)})
+	if err := ix.Apply(context.Background(), f); err != nil {
+		t.Fatal(err)
+	}
+	reportToolchain(t, ix, "mesh-build-go", "novox", "go", "go1.27.1")
+	reportToolchain(t, ix, "mesh-build-go", "ace", "go", "go1.27.1")
+	b := &takeInBed{ix: ix, mods: mods, pending: newMem(), bridge: map[string][]byte{}, base: f, logs: &strings.Builder{}}
+	ix.Verdicts = newMem()
+	b.pending.maxValue = buscompose.StateMaxValueBytes
+	ix.Pending = b.pending
+	ix.Message = func(_ context.Context, repository, merge string) ([]byte, error) {
+		if data, ok := b.bridge[repository+"@"+merge]; ok {
+			return data, nil
+		}
+		return nil, errors.New("the gate holds no merge of " + repository + " with that commit")
+	}
+	ix.SayTakeIn = func(_ context.Context, t takein.TakeIn) error { b.said = append(b.said, t); return nil }
+	logf := ix.Logf
+	ix.Logf = func(format string, args ...any) {
+		b.logs.WriteString(format + "\n")
+		if logf != nil {
+			logf(format, args...)
+		}
+	}
+	own := b.fp(t, delivery.IndexerModule)
+	if own == "" || b.fp(t, "avahi") == "" {
+		t.Fatalf("the bed's modules have no fingerprint")
+	}
+	ix.OwnBuild = func(context.Context) (string, error) { return own, nil }
+	ix.OwnBuildState = newMem()
+	ix.FixOwnBuild(context.Background()) // fixed once, at the start
+	return b
+}
+
+func (b *takeInBed) fp(t *testing.T, module string) string {
+	t.Helper()
+	m, _ := moduleOf(t, b.mods, module)
+	return m.FP2
+}
+
+func (b *takeInBed) commit(t *testing.T, module string) string {
+	t.Helper()
+	m, _ := moduleOf(t, b.mods, module)
+	return m.Commit
+}
+
+// merge is a catalogue merge at commit c whose trees of avahi and the indexer are given ("" keeps the base's).
+func (b *takeInBed) merge(number int, c, avahi, indexer string) forgemsg.Forge {
+	f := b.base
+	f.Number, f.Merge, f.Head = number, c, c
+	f.Trees = map[string]string{}
+	for dir, tree := range b.base.Trees {
+		f.Trees[dir] = tree
+	}
+	if avahi != "" {
+		f.Trees["modules/avahi"] = avahi
+	}
+	if indexer != "" {
+		f.Trees["modules/"+delivery.IndexerModule] = indexer
+	}
+	return f
+}
+
+func (b *takeInBed) arrive(t *testing.T, seq uint64, f forgemsg.Forge) {
+	t.Helper()
+	b.publish(t, f)
+	if _, _, err := b.ix.Arrive(context.Background(), seq, f); err != nil {
+		t.Fatalf("arrive %d: %v", seq, err)
+	}
+}
+
+// publish lets the bed's forge bridge answer the merged message f, as bridge_merged_message does.
+func (b *takeInBed) publish(t *testing.T, f forgemsg.Forge) {
+	t.Helper()
+	data, err := forgemsg.EncodeForge(f)
+	if err != nil {
+		t.Fatal(err)
+	}
+	b.bridge[f.Repository+"@"+f.Merge] = data
+}
+
+func (b *takeInBed) keys() []string {
+	k, _ := b.pending.Keys(context.Background())
+	slices.Sort(k)
+	return k
+}
+
+func (b *takeInBed) events() []string {
+	var out []string
+	for _, s := range b.said {
+		out = append(out, s.Kind+" "+s.Key)
+	}
+	return out
+}
+
+func sha(c byte) string { return strings.Repeat(string(c), 40) }
+
+func TestTakeIn(t *testing.T) { // 1585/T3-T13 (ADR 0633)
+	ctx := context.Background()
+	t.Run("T6 a merge while the own build is unknown writes nothing", func(t *testing.T) {
+		b := newTakeInBed(t)
+		b.ix.ownFP, b.ix.ownFixed = "", false // this process is started again and asks the engine, which does not answer
+		b.ix.OwnBuild = func(context.Context) (string, error) { return "", errors.New("the engine does not answer") }
+		b.ix.FixOwnBuild(ctx)
+		b.said = nil
+		_, _, err := b.ix.Arrive(ctx, 1, b.merge(20, sha('b'), "tree-avahi-2", ""))
+		if !errors.Is(err, ErrOwnBuildUnknown) || len(b.keys()) != 0 || b.commit(t, "avahi") == sha('b') {
+			t.Errorf("err %v, pending %v, avahi at %s: want ErrOwnBuildUnknown and nothing written", err, b.keys(), b.commit(t, "avahi"))
+		}
+		// The merge is said pending with why and since when (so the watchman's bound covers it), and indexer_pending says the
+		// build is unknown, from the own-build state.
+		if len(b.said) != 1 || b.said[0].Kind != takein.TakeInPending || b.said[0].Key != takein.PendingKey(1) || !strings.Contains(b.said[0].Unknown, "does not answer") ||
+			b.said[0].Since.IsZero() || b.said[0].WaitsFor != "" {
+			t.Errorf("said %+v, want one take-in.pending of m.1 saying why the own build is unknown", b.said)
+		} else if _, err := takein.EncodeTakeIn(b.said[0]); err != nil {
+			t.Errorf("the unknown-build event is refused by its own contract: %v", err)
+		}
+		answer, err := PendingTools(b.pending, b.ix.OwnBuildState, nil, nil)[0].Run(map[string]any{})
+		if a, _ := answer.(takein.PendingAnswer); err != nil || !strings.Contains(a.OwnBuildUnknown, "does not answer") || a.OwnBuildSince.IsZero() {
+			t.Errorf("indexer_pending = %+v %v, want the build unknown with why and since", answer, err)
+		}
+		// Before the pending state is on the bus nothing waits: the start asks no build, and the merge is taken in at once,
+		// as before ADR 0633, though the build is unknown (TestIndexerWhole found the start waiting on it for ever).
+		b.ix.Pending = &memStore{unbound: process.ErrNotYet}
+		if _, _, err := b.ix.TakeInAtStart(ctx); err != nil {
+			t.Fatal(err)
+		}
+		if _, _, err := b.ix.Arrive(ctx, 1, b.merge(20, sha('b'), "tree-avahi-2", "")); err != nil || b.commit(t, "avahi") != sha('b') {
+			t.Errorf("no pending state: err %v, avahi at %s: want the merge taken in at once", err, b.commit(t, "avahi"))
+		}
+	})
+	t.Run("T7 and T3 a merge alone, an indexer change, a merge behind it and a revert", func(t *testing.T) {
+		b := newTakeInBed(t)
+		own, avahi0 := b.fp(t, delivery.IndexerModule), b.fp(t, "avahi")
+		// A merge with no change to the indexer and nothing pending is taken in alone, as before.
+		b.arrive(t, 1, b.merge(20, sha('b'), "tree-avahi-2", ""))
+		if avahi1 := b.fp(t, "avahi"); avahi1 == avahi0 || len(b.keys()) != 0 || len(b.said) != 0 {
+			t.Fatalf("alone: avahi %s (was %s), pending %v, said %v: want taken in", avahi1, avahi0, b.keys(), b.events())
+		}
+		avahi1, verdicts := b.fp(t, "avahi"), len(b.ix.Verdicts.(*memStore).vals)
+		// T4: a change to the indexer writes only its entry (with its graph key and verdict); the rest is pending.
+		b.arrive(t, 2, b.merge(21, sha('c'), "tree-avahi-3", "tree-indexer-2"))
+		named := b.fp(t, delivery.IndexerModule)
+		if named == own || b.fp(t, "avahi") != avahi1 || b.commit(t, "avahi") != sha('b') {
+			t.Fatalf("indexer change: indexer %s (own %s), avahi %s at %s: want only the indexer written", named, own, b.fp(t, "avahi"), b.commit(t, "avahi"))
+		}
+		if g := graphOf(t, b.ix, delivery.IndexerModule); g.FP != named {
+			t.Errorf("graph of the indexer names %s, want %s", g.FP, named)
+		}
+		if n := len(b.ix.Verdicts.(*memStore).vals); n > verdicts+1 {
+			t.Errorf("verdicts %d, want at most %d: only the new indexer manifest's", n, verdicts+1)
+		}
+		if want := []string{takein.PendingKey(2)}; !reflect.DeepEqual(b.keys(), want) || !slices.Equal(b.events(), []string{"pending " + takein.PendingKey(2)}) || b.said[0].WaitsFor != named {
+			t.Fatalf("pending %v, said %+v: want m.2 pending for %s", b.keys(), b.said, named)
+		}
+		// T5: the merge delivered again writes no second key and says nothing again.
+		b.arrive(t, 2, b.merge(21, sha('c'), "tree-avahi-3", "tree-indexer-2"))
+		if len(b.keys()) != 1 || len(b.said) != 1 {
+			t.Errorf("redelivered: pending %v, said %v", b.keys(), b.events())
+		}
+		// A later merge joins: the newest governs and still names the new indexer.
+		b.arrive(t, 3, b.merge(22, sha('d'), "tree-avahi-4", "tree-indexer-2"))
+		if len(b.keys()) != 2 || b.commit(t, "avahi") != sha('b') || len(b.said) != 1 {
+			t.Fatalf("behind: pending %v, avahi at %s, said %v: want both pending and nothing said again", b.keys(), b.commit(t, "avahi"), b.events())
+		}
+		// A revert brings the indexer back to the running build: everything is taken in, oldest first.
+		b.arrive(t, 4, b.merge(23, sha('e'), "tree-avahi-5", b.base.Trees["modules/"+delivery.IndexerModule]))
+		if len(b.keys()) != 0 || b.fp(t, delivery.IndexerModule) != own || b.commit(t, "avahi") != sha('e') {
+			t.Fatalf("revert: pending %v, indexer %s, avahi at %s: want all taken in", b.keys(), b.fp(t, delivery.IndexerModule), b.commit(t, "avahi"))
+		}
+		if want := []string{"pending " + takein.PendingKey(2), "taken " + takein.PendingKey(2)}; !slices.Equal(b.events(), want) {
+			t.Errorf("said %v, want %v", b.events(), want)
+		}
+	})
+	t.Run("K1 the indexer a revision names is judged with the seat definitions the revision carries", func(t *testing.T) {
+		// A successor's manifest invokes a verb of the node-engine's seat that the built-in list lacks and the revision's
+		// definitions add (ADR 0633 §1, §6): refused without them, with its reason said on the wait and in indexer_pending;
+		// accepted with them, and the revision waits for the build it names.
+		const verb, contracts = "manifest-reads", "modules/seat-contracts"
+		for _, row := range []struct {
+			name    string
+			defined bool
+			refused bool
+		}{{"definitions the revision does not carry", false, true}, {"definitions the revision carries", true, false}} {
+			b := newTakeInBed(t)
+			f := b.merge(21, sha('c'), "tree-avahi-3", "tree-indexer-2")
+			f.Manifests = map[string]string{}
+			for dir, raw := range b.base.Manifests {
+				f.Manifests[dir] = raw
+			}
+			dir := "modules/" + delivery.IndexerModule
+			f.Manifests[dir] = strings.Replace(f.Manifests[dir], `"module": "`+delivery.IndexerModule+`"`,
+				`"module": "`+delivery.IndexerModule+`", "invokes": ["seat:node-engine.`+verb+`"]`, 1)
+			if row.defined {
+				f.Trees[contracts] = "tree-seat-contracts"
+				f.Locks = map[string]map[string]string{}
+				for d, l := range b.base.Locks {
+					f.Locks[d] = l
+				}
+				f.Locks[contracts] = map[string]string{}
+				f.Manifests[contracts] = `{"module":"seat-contracts","version":"1","build":{"artifacts":[{"name":"go-seats","kind":"package","language":"go","paths":["go"],"generated-from":"."}]}}`
+				b.ix.Files = func(_ context.Context, repository, commit string, dirs []string) (map[string]map[string]string, error) {
+					if repository != f.Repository || commit != f.Merge || !slices.Equal(dirs, []string{contracts + "/seats"}) {
+						t.Errorf("listed %v of %s at %s", dirs, repository, commit)
+					}
+					return map[string]map[string]string{dirs[0]: {"node-engine/seat.json": "1", "node-engine/fixtures/a.json": "2"}}, nil
+				}
+				b.ix.ReadFile = func(_ context.Context, _, _, p string) ([]byte, error) {
+					switch p {
+					case contracts + "/seats/node-engine/seat.json":
+						return []byte(`{"format":1,"seat":"node-engine","scope":"node","includes":["reads"]}`), nil
+					case contracts + "/parts/reads.json":
+						return []byte(`{"format":1,"part":"reads","verbs":[{"name":"` + verb + `"}]}`), nil
+					}
+					return nil, nil
+				}
+			}
+			b.arrive(t, 2, f)
+			waits := PendingWaits(readPending(t, b))
+			refused := ""
+			if len(b.said) > 0 {
+				refused = b.said[0].Refused
+			}
+			if got := strings.Contains(refused, `serves no verb "`+verb+`"`); got != row.refused || (len(waits) == 1 && waits[0].Refused != refused) {
+				t.Errorf("%s: said %q, indexer_pending %+v: want a refusal naming the verb %v", row.name, refused, waits, row.refused)
+			}
+			if _, ok := catalogue.SeatNamed("node-engine"); !ok || judgeSeatsHave("node-engine", verb) {
+				t.Errorf("%s: the seats are not put back after the dry run", row.name)
+			}
+		}
+	})
+	t.Run("T10 the named indexer takes the revision in at its start; a gathered group stays", func(t *testing.T) {
+		b := newTakeInBed(t)
+		b.arrive(t, 2, b.merge(21, sha('c'), "tree-avahi-3", "tree-indexer-2"))
+		g := b.merge(30, sha('f'), "", "")
+		g.Repository, g.Trees, g.Manifests, g.Locks, g.Group = "novox/mesh-sdk", map[string]string{}, nil, nil, "feat/x"
+		g.Members = []delivery.Head{{Repository: "novox/mesh-sdk", Number: 30, Head: g.Head}, {Repository: "novox/mesh-host", Number: 4, Head: sha('9')}}
+		b.arrive(t, 5, g)
+		named := b.fp(t, delivery.IndexerModule)
+		// The new indexer starts; its build is not known (the engine does not answer at its start): a hand ask is answered
+		// meanwhile (R5), and the start waits for nothing. It is never asked again, so it stays unknown until it is started again.
+		mk := func(ask func(context.Context) (string, error)) *Indexer {
+			n := &Indexer{Store: b.ix.Store, Modules: b.ix.Modules, Manifests: b.ix.Manifests, Graph: b.ix.Graph, Verdicts: b.ix.Verdicts,
+				Packages: b.ix.Packages, Builds: b.ix.Builds, Pending: b.pending, Message: b.ix.Message, SayTakeIn: b.ix.SayTakeIn, Logf: b.ix.Logf, GoSum: b.ix.GoSum}
+			n.toolchains = b.ix.toolchains
+			n.OwnBuild = ask
+			n.FixOwnBuild(ctx)
+			return n
+		}
+		// A start that decides nothing says so (issue 1921): the build it learnt, the build the held wait names, also when the
+		// wait was said before; and indexer_pending names the known build and since when.
+		oldBuild, _ := b.ix.OwnBuild(ctx)
+		oldStart := mk(func(context.Context) (string, error) { return oldBuild, nil })
+		b.logs.Reset()
+		if _, words, err := oldStart.TakeInAtStart(ctx); err != nil || len(b.keys()) != 2 || !strings.Contains(b.logs.String(), "still name the indexer build") ||
+			!strings.Contains(b.logs.String(), "at the start, this program runs build") {
+			t.Fatalf("a start that holds: %q %v, journal %q: want the build learnt and the build the wait names said", words, err, b.logs.String())
+		}
+		if answer, err := PendingTools(b.pending, b.ix.OwnBuildState, nil, nil)[0].Run(map[string]any{}); err != nil || answer.(takein.PendingAnswer).OwnBuild != oldBuild || answer.(takein.PendingAnswer).OwnBuildSince.IsZero() {
+			t.Errorf("indexer_pending = %+v %v, want the known build and since", answer, err)
+		}
+		asked := 0
+		next := mk(func(context.Context) (string, error) { asked++; return "", errors.New("not yet") })
+		if r := next.TakeInPendingByHand(ctx, "m.nothing", "lead@shanks", "a test"); r.Stored || !strings.Contains(r.Answer, "nothing waits") {
+			t.Errorf("a hand ask while the own build is unknown: %+v", r)
+		}
+		if _, words, err := next.TakeInAtStart(ctx); err != nil || len(b.keys()) != 2 || !strings.Contains(words, "not known") {
+			t.Fatalf("a start with its build unknown: %q %v, pending %v: want it to answer at once and take nothing in", words, err, b.keys())
+		}
+		// The engine answers now, and the same process does not ask it again: it learnt nothing it did not know at its start.
+		next.OwnBuild = func(context.Context) (string, error) { asked++; return named, nil }
+		if _, words, err := next.TakeInAtStart(ctx); err != nil || asked != 1 || len(b.keys()) != 2 || !strings.Contains(words, "not known") {
+			t.Fatalf("the window of a replacement: %q %v, asked %d, pending %v: want the build fixed at the start, never learnt later", words, err, asked, b.keys())
+		}
+		// The module started again fixes the build at its start and takes the revision in.
+		next = mk(func(context.Context) (string, error) { return named, nil })
+		if _, _, err := next.TakeInAtStart(ctx); err != nil {
+			t.Fatal(err)
+		}
+		if !reflect.DeepEqual(b.keys(), []string{takein.PendingKey(5)}) || b.commit(t, "avahi") != sha('c') {
+			t.Errorf("start: pending %v, avahi at %s: want the revision taken in, the group left", b.keys(), b.commit(t, "avahi"))
+		}
+	})
+	t.Run("T8 T9 T11 a group gathered until its end, a merge behind it, one alone, an end again", func(t *testing.T) {
+		b := newTakeInBed(t)
+		b.ix.Taken = newMem()
+		// The commits in the order they were made: one is in another when it comes first.
+		order := "a756bc"
+		b.ix.Contains = func(_ context.Context, _, commit, in string) (bool, error) {
+			return strings.IndexByte(order, commit[0]) <= strings.IndexByte(order, in[0]), nil
+		}
+		member := func(repo string, number int, c string) forgemsg.Forge {
+			f := b.merge(number, c, "", "")
+			f.Group = "feat/take-in"
+			f.Members = []delivery.Head{{Repository: catalogueRepo, Number: 40, Head: sha('1')}, {Repository: "novox/mesh-sdk", Number: 41, Head: sha('2')}}
+			if repo != catalogueRepo {
+				f.Repository, f.Trees, f.Manifests, f.Locks = repo, map[string]string{}, nil, nil
+			}
+			f.Head = map[int]string{40: sha('1'), 41: sha('2')}[number]
+			return f
+		}
+		b.arrive(t, 1, member(catalogueRepo, 40, sha('7')))
+		if b.commit(t, "avahi") == sha('7') || !slices.Equal(b.events(), []string{"pending g.feat/take-in"}) {
+			t.Fatalf("first member: avahi at %s, said %v: want held, the group said pending", b.commit(t, "avahi"), b.events())
+		}
+		// A merge in another repository is taken in alone; one in a member's repository waits behind the group.
+		alone := b.merge(50, sha('5'), "", "")
+		alone.Repository, alone.Trees, alone.Manifests, alone.Locks = "novox/hq", map[string]string{}, nil, nil
+		b.arrive(t, 2, alone)
+		b.arrive(t, 3, b.merge(51, sha('6'), "tree-avahi-9", ""))
+		if !reflect.DeepEqual(b.keys(), []string{takein.PendingKey(1), takein.PendingKey(3)}) {
+			t.Fatalf("pending %v: want the member and the merge behind it", b.keys())
+		}
+		end := forgemsg.ForgeGroupEnd{Group: "feat/take-in", Members: []forgemsg.GroupMerge{{Repository: catalogueRepo, Number: 40, Merge: sha('7')}, {Repository: "novox/mesh-sdk", Number: 41, Merge: sha('b')}}}
+		if _, _, err := b.ix.EndGroup(ctx, end); err == nil {
+			t.Fatal("an end before its last member is taken in")
+		}
+		b.arrive(t, 4, member("novox/mesh-sdk", 41, sha('b')))
+		if _, _, err := b.ix.EndGroup(ctx, end); err != nil {
+			t.Fatal(err)
+		}
+		if len(b.keys()) != 0 || b.commit(t, "avahi") != sha('6') {
+			t.Fatalf("end: pending %v, avahi at %s: want the group and the merge behind it taken in", b.keys(), b.commit(t, "avahi"))
+		}
+		if want := []string{"pending g.feat/take-in", "pending g.feat/take-in", "taken g.feat/take-in"}; !slices.Equal(b.events(), want) {
+			t.Errorf("said %v, want %v", b.events(), want)
+		}
+		// R1: the end published again after the take-in changes nothing and is not delivered again.
+		if _, words, err := b.ix.EndGroup(ctx, end); err != nil || !strings.Contains(words, "taken in already") {
+			t.Errorf("an end again: %q %v", words, err)
+		}
+		// T11 (the lead's row): a group whose revision changes the indexer: the group's wait is taken, then the revision pending.
+		b.said = nil
+		g := member(catalogueRepo, 40, sha('c'))
+		g.Group, g.Trees = "feat/two", b.merge(0, "", "", "tree-indexer-7").Trees
+		g.Members = g.Members[:1]
+		b.arrive(t, 9, g)
+		if _, _, err := b.ix.EndGroup(ctx, forgemsg.ForgeGroupEnd{Group: "feat/two", Members: []forgemsg.GroupMerge{{Repository: catalogueRepo, Number: 40, Merge: sha('c')}}}); err != nil {
+			t.Fatal(err)
+		}
+		if want := []string{"pending g.feat/two", "taken g.feat/two", "pending " + takein.PendingKey(9)}; !slices.Equal(b.events(), want) {
+			t.Errorf("a group naming another indexer: said %v, want %v", b.events(), want)
+		}
+	})
+	t.Run("T5 two take-ins of one pending revision: the one that loses the claim writes nothing", func(t *testing.T) {
+		b := newTakeInBed(t)
+		b.arrive(t, 2, b.merge(21, sha('c'), "tree-avahi-3", "tree-indexer-2"))
+		named := b.fp(t, delivery.IndexerModule)
+		b.ix.ownMu.Lock()
+		b.ix.ownFP = named
+		b.ix.ownMu.Unlock()
+		// The other indexer claims the merge between this one's read and its claim.
+		b.pending.beforeWrite = func() {
+			v := b.pending.vals[takein.PendingKey(2)]
+			var p Pending
+			_ = json.Unmarshal(v, &p)
+			p.Taking = "the other indexer"
+			data, _ := json.Marshal(p)
+			b.pending.put(takein.PendingKey(2), data)
+		}
+		if _, _, err := b.ix.TakeInAtStart(ctx); err != nil {
+			t.Fatal(err)
+		}
+		if b.commit(t, "avahi") == sha('c') || len(b.keys()) != 1 || !strings.Contains(b.logs.String(), "is lost") {
+			t.Errorf("avahi at %s, pending %v: want nothing taken in by the loser, and it said", b.commit(t, "avahi"), b.keys())
+		}
+	})
+	t.Run("T5 a take-in whose store fails once leaves no claim behind, and is taken in after", func(t *testing.T) {
+		claims := func(b *takeInBed) []string {
+			var out []string
+			for _, k := range b.keys() {
+				var p Pending
+				_ = json.Unmarshal(b.pending.vals[k], &p)
+				if p.Taking != "" {
+					out = append(out, k)
+				}
+			}
+			return out
+		}
+		once := func(match func(key string) bool) func(string) error {
+			done := false
+			return func(key string) error {
+				if !done && match(key) {
+					done = true
+					return errors.New("the store failed once")
+				}
+				return nil
+			}
+		}
+		for _, c := range []struct {
+			name string
+			fail func(b *takeInBed)
+		}{
+			// The second merge's claim fails: the first's, already made, is released.
+			{"a claim lost", func(b *takeInBed) {
+				b.pending.failWrite = once(func(k string) bool { return k == takein.PendingKey(3) })
+			}},
+			// The take-in itself fails on a module's write after both claims: both are released.
+			{"a take-in that fails", func(b *takeInBed) { b.mods.failWrite = once(func(string) bool { return true }) }},
+		} {
+			b := newTakeInBed(t)
+			b.arrive(t, 2, b.merge(21, sha('c'), "tree-avahi-3", "tree-indexer-2"))
+			b.arrive(t, 3, b.merge(22, sha('d'), "tree-avahi-4", "tree-indexer-2"))
+			named := b.fp(t, delivery.IndexerModule)
+			b.ix.ownMu.Lock()
+			b.ix.ownFP = named
+			b.ix.ownMu.Unlock()
+			c.fail(b)
+			_, _, _ = b.ix.TakeInAtStart(ctx)
+			if got := claims(b); len(got) != 0 || len(b.keys()) != 2 {
+				t.Fatalf("%s: pending %v, claimed %v: want both pending and no claim left", c.name, b.keys(), got)
+			}
+			// The next take-in, not at a start, is not refused by a claim left behind: it takes both in.
+			b.arrive(t, 4, b.merge(23, sha('e'), "tree-avahi-5", "tree-indexer-2"))
+			if len(b.keys()) != 0 || b.commit(t, "avahi") != sha('e') {
+				t.Errorf("%s: after: pending %v, avahi at %s: want all taken in", c.name, b.keys(), b.commit(t, "avahi"))
+			}
+		}
+	})
+	t.Run("T7 a toolchain report evaluates pending again: the revision then names the running build and is taken in", func(t *testing.T) {
+		b := newTakeInBed(t)
+		b.arrive(t, 2, b.merge(21, sha('c'), "tree-avahi-3", "tree-indexer-2"))
+		entries, err := ReadPending(ctx, b.pending, nil)
+		if err != nil {
+			t.Fatal(err)
+		}
+		// The build the revision names under the next toolchain, worked out on a dry indexer; this one runs it.
+		x := b.ix.dry().ix
+		for _, node := range []string{"novox", "ace"} {
+			key, _ := delivery.ToolchainKey(node, "go")
+			x.PutToolchain("mesh-build-go", key, toolchainValue(t, "go", "go1.27.2", "1"), false)
+		}
+		ready, _, _ := b.ix.loadNewest(ctx, WaitsOf(entries).Ready)
+		next, _, err := x.computeOver(ctx, ready)
+		if err != nil || next == "" || next == b.said[0].WaitsFor {
+			t.Fatalf("the build under the next toolchain: %q %v (the revision names %s)", next, err, b.said[0].WaitsFor)
+		}
+		b.ix.ownMu.Lock()
+		b.ix.ownFP = next
+		b.ix.ownMu.Unlock()
+		reportToolchain(t, b.ix, "mesh-build-go", "novox", "go", "go1.27.2")
+		if len(b.keys()) != 1 {
+			t.Fatalf("one node's report: pending %v, want the revision still held (the nodes disagree)", b.keys())
+		}
+		reportToolchain(t, b.ix, "mesh-build-go", "ace", "go", "go1.27.2")
+		if len(b.keys()) != 0 || b.commit(t, "avahi") != sha('c') {
+			t.Errorf("after the toolchain report: pending %v, avahi at %s: want the revision taken in", b.keys(), b.commit(t, "avahi"))
+		}
+	})
+	t.Run("T12 T13 indexer_pending names the wait; a hand take-in and a drop say what they ended", func(t *testing.T) {
+		b := newTakeInBed(t)
+		b.arrive(t, 2, b.merge(21, sha('c'), "tree-avahi-3", "tree-indexer-2"))
+		b.arrive(t, 3, b.merge(22, sha('d'), "tree-avahi-4", "tree-indexer-2"))
+		var answer takein.PendingAnswer
+		for _, tool := range PendingTools(b.pending, nil, nil, nil) {
+			if tool.Name == PendingTool {
+				out, err := tool.Run(map[string]any{})
+				if err != nil {
+					t.Fatal(err)
+				}
+				answer = out.(takein.PendingAnswer)
+			}
+		}
+		if len(answer.Waits) != 1 || answer.Waits[0].Key != takein.PendingKey(2) || !slices.Equal(answer.Waits[0].Holds, []string{"avahi", delivery.IndexerModule}) ||
+			answer.Waits[0].Said != takein.TakeInPendingEvent || len(answer.Waits[0].Keys) != 2 {
+			t.Fatalf("indexer_pending = %+v", answer)
+		}
+		b.said = nil
+		if r := b.ix.DropPending(ctx, takein.PendingKey(2), "lead@shanks", "replaced by m.3"); !r.Stored {
+			t.Fatalf("drop: %+v", r)
+		}
+		if len(b.said) < 2 || !b.said[0].Dropped || b.said[0].Key != takein.PendingKey(2) || b.said[0].By != "lead@shanks" || b.said[1].Key != takein.PendingKey(3) {
+			t.Fatalf("drop said %+v: want m.2 taken (dropped, by) and m.3 pending", b.said)
+		}
+		b.said = nil
+		if r := b.ix.TakeInPendingByHand(ctx, takein.PendingKey(3), "lead@shanks", "the named indexer can never run"); !r.Stored {
+			t.Fatalf("hand take-in: %+v", r)
+		}
+		if len(b.keys()) != 0 || b.commit(t, "avahi") != sha('d') || len(b.said) != 1 || b.said[0].Kind != takein.TakeInTaken || b.said[0].By != "lead@shanks" {
+			t.Errorf("hand take-in: pending %v, avahi at %s, said %+v", b.keys(), b.commit(t, "avahi"), b.said)
+		}
+	})
+	t.Run("1585 a merge over the value cap is held by reference, a new indexer with an empty memory takes it in through the forge bridge, and a covered pull request leaves its candidate", func(t *testing.T) {
+		big := func(f forgemsg.Forge) forgemsg.Forge {
+			f.Words = strings.Repeat("x", 300*1024)
+			f.Branch = "feat/g"
+			return f
+		}
+		b := newTakeInBed(t)
+		avahi0 := b.fp(t, "avahi")
+		// The forge bridge is not asked at all while the merges are in memory: a 300 KiB merge, over the bucket's cap whole,
+		// is held by reference and a lone one taken in.
+		bridgeDown := func(context.Context, string, string) ([]byte, error) {
+			return nil, errors.New("the bridge does not answer")
+		}
+		answers := b.ix.Message
+		b.ix.Message = bridgeDown
+		b.arrive(t, 1, big(b.merge(20, sha('b'), "tree-avahi-2", "")))
+		if b.fp(t, "avahi") == avahi0 || b.commit(t, "avahi") != sha('b') || len(b.keys()) != 0 || len(b.ix.held) != 0 {
+			t.Fatalf("a big merge alone: avahi at %s, pending %v, in memory %d: want it taken in and forgotten", b.commit(t, "avahi"), b.keys(), len(b.ix.held))
+		}
+		// Two pull requests of one group are open; both then merge (the indexer changed: held for the new build).
+		for n, head := range map[int]string{21: sha('1'), 22: sha('2')} {
+			if err := b.ix.Apply(ctx, pull(catalogueRepo, n, "feat/g", head, "modules/avahi")); err != nil {
+				t.Fatal(err)
+			}
+		}
+		key, _ := delivery.CandidatesKey("feat/g")
+		if _, _, found, _ := b.ix.Store.Get(ctx, key); !found {
+			t.Fatal("the group has no candidate")
+		}
+		b.arrive(t, 2, big(b.merge(21, sha('c'), "tree-avahi-3", "tree-indexer-2")))
+		b.arrive(t, 3, big(b.merge(22, sha('d'), "tree-avahi-4", "tree-indexer-2")))
+		raw, _, _, _ := b.pending.Get(ctx, takein.PendingKey(2))
+		if len(b.keys()) != 2 || len(raw) > 4096 || b.commit(t, "avahi") != sha('b') {
+			t.Fatalf("a big merge held: pending %v, value %d bytes, avahi at %s: want two small values", b.keys(), len(raw), b.commit(t, "avahi"))
+		}
+		named := b.fp(t, delivery.IndexerModule)
+		// The new indexer starts with nothing in memory and the bridge down: the newest merge is said lost with the bridge's
+		// words (event, state), the older one is covered and not lost, and nothing is taken in.
+		next := &Indexer{Store: b.ix.Store, Modules: b.ix.Modules, Manifests: b.ix.Manifests, Graph: b.ix.Graph, Verdicts: b.ix.Verdicts,
+			Packages: b.ix.Packages, Builds: b.ix.Builds, Pending: b.pending, Message: bridgeDown, SayTakeIn: b.ix.SayTakeIn, Logf: b.ix.Logf,
+			GoSum: b.ix.GoSum, OwnBuild: func(context.Context) (string, error) { return named, nil }}
+		next.toolchains = b.ix.toolchains
+		next.FixOwnBuild(ctx)
+		b.said = nil
+		if _, _, err := next.TakeInAtStart(ctx); err != nil {
+			t.Fatal(err)
+		}
+		waits := PendingWaits(mustReadPending(t, b))
+		if len(b.said) != 1 || !slices.Equal(b.said[0].Lost, []string{takein.PendingKey(3)}) || len(waits) != 1 || !slices.Equal(waits[0].Lost, []string{takein.PendingKey(3)}) || b.commit(t, "avahi") != sha('b') {
+			t.Fatalf("lost: said %+v, waits %+v, avahi at %s: want m.3 lost on the event and in indexer_pending, nothing taken in", b.said, waits, b.commit(t, "avahi"))
+		}
+		if v, _, _, _ := b.pending.Get(ctx, takein.PendingKey(3)); !strings.Contains(string(v), "the bridge does not answer") {
+			t.Errorf("m.3 = %s: want the bridge's words", v)
+		}
+		if err := next.PendingAgain(ctx); err != nil || len(b.said) != 1 {
+			t.Errorf("lost again: err %v, said %v: want it said once", err, b.events())
+		}
+		if r := next.TakeInPendingByHand(ctx, takein.PendingKey(2), "lead@shanks", "try"); r.Stored || b.commit(t, "avahi") != sha('b') {
+			t.Errorf("hand take-in of a lost merge: %+v, avahi at %s: want nothing taken in", r, b.commit(t, "avahi"))
+		}
+		// The bridge answers: the newest merge is read through it, the older one is covered, and the revision is taken in.
+		b.publish(t, b.merge(22, sha('d'), "tree-avahi-4", "tree-indexer-2")) // the answer is the message as published, small here
+		next.Message = answers
+		b.bridge[catalogueRepo+"@"+sha('d')], _ = forgemsg.EncodeForge(big(b.merge(22, sha('d'), "tree-avahi-4", "tree-indexer-2")))
+		b.logs.Reset()
+		if err := next.PendingAgain(ctx); err != nil {
+			t.Fatal(err)
+		}
+		if len(b.keys()) != 0 || b.commit(t, "avahi") != sha('d') || !strings.Contains(b.logs.String(), "is covered by") {
+			t.Fatalf("taken in: pending %v, avahi at %s, journal %q: want both merges taken in, the older covered", b.keys(), b.commit(t, "avahi"), b.logs.String())
+		}
+		if _, _, found, _ := b.ix.Store.Get(ctx, key); found {
+			t.Errorf("the group's candidate stays after both its pull requests merged (the covered one is not taken out)")
+		}
+		// A hand take-in of a merge by its commit asks the bridge and runs the message through Arrive.
+		b.ix.Message = answers
+		b.publish(t, big(b.merge(30, sha('e'), "tree-avahi-6", b.base.Trees["modules/"+delivery.IndexerModule])))
+		if r := b.ix.TakeInMerge(ctx, catalogueRepo, sha('e'), 9, "lead@shanks", "held by the cap"); !r.Stored || b.commit(t, "avahi") != sha('e') {
+			t.Fatalf("merge take-in: %+v, avahi at %s: want it taken in", r, b.commit(t, "avahi"))
+		}
+		if r := b.ix.TakeInMerge(ctx, catalogueRepo, sha('9'), 10, "lead@shanks", "no such"); r.Stored || !strings.Contains(r.Answer, "gate holds no merge") {
+			t.Errorf("merge take-in of a merge the bridge does not know: %+v", r)
+		}
+		// An old value that holds the message whole reads as before.
+		old := b.merge(31, sha('f'), "tree-avahi-7", b.base.Trees["modules/"+delivery.IndexerModule])
+		rawOld, _ := forgemsg.EncodeForge(old)
+		data, _ := encodePending(Pending{Forge: rawOld, Since: b.ix.now(), LastWriter: b.fp(t, delivery.IndexerModule)})
+		if err := b.pending.Create(ctx, takein.PendingKey(11), data); err != nil {
+			t.Fatal(err)
+		}
+		if err := b.ix.PendingAgain(ctx); err != nil || b.commit(t, "avahi") != sha('f') {
+			t.Errorf("an old value with the message whole: err %v, avahi at %s: want it taken in", err, b.commit(t, "avahi"))
+		}
+	})
+	t.Run("the dry run names every field of the indexer", func(t *testing.T) {
+		// dry (pending.go) builds an indexer field by field: a field added to Indexer is named there, or this fails.
+		named := map[string]bool{}
+		for _, f := range []string{"Store", "Modules", "Manifests", "Predefined", "ConfigCandidates", "Taken", "Verdicts", "OldSections",
+			"JudgeID", "SayRefused", "SayAccepted", "Packages", "Graph", "Files", "GoSum", "GoMod", "Now", "Builds", "Named", "Trunk",
+			"Read", "Contains", "Logf", "ReadOpen", "OwnBuild", "Message", "Pending", "SayTakeIn", "ReadFile", "OpenTries", "TryRecovery", "OwnBuildState"} {
+			named[f] = true
+		}
+		ty := reflect.TypeOf(Indexer{})
+		for i := range ty.NumField() {
+			if f := ty.Field(i); f.IsExported() && !named[f.Name] {
+				t.Errorf("Indexer.%s is not named by dry", f.Name)
+			}
+		}
+	})
+}
+
+func mustReadPending(t *testing.T, b *takeInBed) []PendingEntry {
+	t.Helper()
+	entries, err := ReadPending(context.Background(), b.pending, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return entries
+}
+
+// judgeSeatsHave says whether the catalogue's seat list holds the verb on the seat now.
+func judgeSeatsHave(seat, verb string) bool {
+	s, _ := catalogue.SeatNamed(seat)
+	return slices.ContainsFunc(s.Serves, func(v catalogue.Verb) bool { return v.Name == verb })
+}
+
+// readPending is the bed's pending state as indexer_pending reads it.
+func readPending(t *testing.T, b *takeInBed) []PendingEntry {
+	t.Helper()
+	entries, err := ReadPending(context.Background(), b.pending, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return entries
+}
@@ -0,0 +1,205 @@
+package index
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"strings"
+	"time"
+
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+
+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-indexer/takein"
+	stdio "git.novox.be/novox/mesh-sdk/go"
+)
+
+// PendingTools are the indexer's tools of what waits for a take-in (novox/hq ADR 0633 §5): indexer_pending reads the
+// pending state, and indexer_take_in_pending and indexer_drop_pending steer it by an ask in takeins, as indexer_take_in
+// does. pending is the pending state as the tools bundle reads it; ask writes an ask and waits for the indexer's answer.
+func PendingTools(pending, ownBuild Store, ask func(key string, value []byte) (TakeInAsk, error), now func() time.Time) []stdio.Tool {
+	str := func(args map[string]any, k string) string { s, _ := args[k].(string); return s }
+	hand := func(drop bool) func(map[string]any) (any, error) {
+		return func(args map[string]any) (any, error) {
+			key, value, err := NewPendingAsk(str(args, "key"), str(args, "why"), stdio.CallerOf(args), drop, now())
+			if err != nil {
+				return nil, err
+			}
+			a, err := ask(key, value)
+			if err != nil {
+				return nil, err
+			}
+			return a.Result, nil
+		}
+	}
+	merge := func(args map[string]any) (any, error) {
+		seq, _ := args["sequence"].(float64)
+		key, value, err := NewMergeAsk(str(args, "repository"), str(args, "merge"), uint64(seq), str(args, "why"), stdio.CallerOf(args), now())
+		if err != nil {
+			return nil, err
+		}
+		a, err := ask(key, value)
+		if err != nil {
+			return nil, err
+		}
+		return a.Result, nil
+	}
+	return []stdio.Tool{
+		{Name: PendingTool,
+			Description: "What waits for a take-in (ADR 0633): merges the indexer holds in its pending state instead of taking them in. " +
+				"A revision (what revision, its key its oldest merge's m.<sequence>) waits for the build of the indexer it names " +
+				"(waits-for): the running indexer wrote only what building and moving that indexer needs, and the new indexer takes " +
+				"it in at its start. A group (what group, key g.<group>) is a delivery group whose members are gathered until the " +
+				"forge bridge says its end; a merge in one of its members' repositories waits behind it (behind). Each names its " +
+				"merges, since when it waits, the modules it holds back (holds), the merges whose message the forge bridge's stream no " +
+				"longer holds (lost: they are not taken in; indexer_drop_pending drops them) and the last take-in event said of it. Empty waits: " +
+				"every merge is taken in. The watchman raises take-in-waits past 60 minutes for a revision, 30 for a group; " +
+				"indexer_take_in_pending and indexer_drop_pending steer a wait. own-build says which build the indexer knows it runs and own-build-since since when; own-build-unknown, when set, says the indexer cannot learn the build it " +
+				"runs (since when): it fixes it once at its start, so every merge waits (a take-in.pending that says so) until the module is started again.",
+			Input: map[string]any{"type": "object", "properties": map[string]any{}},
+			Run: func(map[string]any) (any, error) {
+				var unread []string
+				entries, err := ReadPending(context.Background(), pending, func(format string, args ...any) {
+					unread = append(unread, fmt.Sprintf(format, args...))
+				})
+				if err != nil {
+					return nil, err
+				}
+				answer := takein.PendingAnswer{Waits: PendingWaits(entries), Unread: unread}
+				// Whether this indexer knows the build it runs: when it does not, every merge waits, and this says since when and why.
+				if ownBuild != nil {
+					if v, _, found, err := ownBuild.Get(context.Background(), OwnBuildKey); err == nil && found {
+						var o OwnBuild
+						if json.Unmarshal(v, &o) == nil {
+							answer.OwnBuildSince = o.Since
+							if o.Known {
+								answer.OwnBuild = o.FP
+							} else {
+								answer.OwnBuildUnknown = o.Why
+							}
+						}
+					}
+				}
+				return answer, nil
+			}},
+		{Name: TakeInPendingTool,
+			Description: "Take a wait in by hand with the running indexer and its judge (ADR 0633 §5): the revision under its m. key, " +
+				"whatever build of the indexer it names, or a delivery group under its g. key with the members gathered so far. For " +
+				"when the named indexer can never run, or a group's end never comes. A hand act: who and why are said in the " +
+				"indexer's journal and on the take-in.taken event, which clears take-in-waits. indexer_pending names the keys.",
+			Input: map[string]any{"type": "object", "required": []string{"key", "why"}, "properties": map[string]any{
+				"key": map[string]any{"type": "string", "description": "the wait's key, m.<sequence> or g.<group>, as indexer_pending names it"},
+				"why": map[string]any{"type": "string", "description": "why it is taken in by hand, in plain words"}}},
+			Run: hand(false)},
+		{Name: DropPendingTool,
+			Description: "Drop one pending merge by hand, abandoned because a later merge replaced it (ADR 0633 §5): it is removed from " +
+				"the pending state and nothing of it is taken in; what waited with it is worked out again. A hand act: who and why are " +
+				"said in the journal and on the take-in.taken event (dropped).",
+			Input: map[string]any{"type": "object", "required": []string{"key", "why"}, "properties": map[string]any{
+				"key": map[string]any{"type": "string", "description": "the pending merge's key, m.<sequence>, as indexer_pending names its merges' wait"},
+				"why": map[string]any{"type": "string", "description": "why it is dropped, in plain words"}}},
+			Run: hand(true)},
+		{Name: TakeInMergeTool,
+			Description: "Take one merge in by hand (ADR 0633 §5, issue 1585): the indexer asks the forge bridge for the merge's merged message " +
+				"(bridge_merged_message) and runs it through the take-in as a delivered merged message, so it is held for the " +
+				"indexer its revision names or taken in. For a merge the take-in did not take in (indexer_heard names its sequence " +
+				"and why). A hand act: who and why are said in the indexer's journal. The bridge's own words answer when it cannot " +
+				"build the message (the gate holds no such merge, the forge does not answer).",
+			Input: map[string]any{"type": "object", "required": []string{"repository", "merge", "sequence", "why"}, "properties": map[string]any{
+				"repository": map[string]any{"type": "string", "description": "the repository, owner/name"},
+				"merge":      map[string]any{"type": "string", "description": "the merge commit, 40 hex digits"},
+				"sequence":   map[string]any{"type": "integer", "description": "the merge's sequence on the forge bridge's stream, as indexer_heard names it"},
+				"why":        map[string]any{"type": "string", "description": "why it is taken in by hand, in plain words"}}},
+			Run: merge},
+	}
+}
+
+// TryCandidateTools are the tools of a group try's candidate (issue 1921, trycandidates.go): indexer_try_candidates reads the
+// candidates the indexer holds for tries (the try, its heads, each member's modules and whether each has its fingerprint),
+// and indexer_drop_try_candidate drops one by an ask in takeins. candidates is the candidates state as the tools bundle reads it.
+func TryCandidateTools(candidates, recovery Store, ask func(key string, value []byte) (TakeInAsk, error), now func() time.Time) []stdio.Tool {
+	return []stdio.Tool{
+		{Name: TryCandidatesTool,
+			Description: "The candidates the indexer holds for group tries (a try of several repositories at exact commits, mesh-delivery-checker try): " +
+				"per try its heads hash, each member's repository and commit, the modules the try touches and, per module, its manifest digest, its " +
+				"fingerprint or why it has none yet (a merge preview not yet written). The checker's manifest validator and the node-engines' " +
+				"compose-candidate read this candidate. Read-only; an empty answer means no whole try waits or runs.",
+			Input: map[string]any{"type": "object", "properties": map[string]any{}},
+			Run: func(map[string]any) (any, error) {
+				ctx := context.Background()
+				keys, err := candidates.Keys(ctx)
+				if err != nil {
+					return nil, err
+				}
+				var out []delivery.Candidate
+				for _, k := range keys {
+					if !IsTryGroup(k) {
+						continue
+					}
+					v, _, found, err := candidates.Get(ctx, k)
+					if err != nil || !found {
+						continue
+					}
+					if c, err := delivery.DecodeCandidate(v); err == nil {
+						out = append(out, c)
+					}
+				}
+				// How the recovery of the open tries went: loud when it is not done (since when, why).
+				said := map[string]any{"done": false, "why": "no recovery has been written yet"}
+				if v, _, found, err := recovery.Get(ctx, TryRecoveryKey); err == nil && found {
+					var r TryRecovery
+					if json.Unmarshal(v, &r) == nil {
+						said = map[string]any{"done": r.Done}
+						if !r.Done {
+							said["why"], said["since"] = r.Why, r.Since
+							said["says"] = "recovery not done, since " + r.Since.Format(time.RFC3339) + ": " + r.Why
+						}
+					}
+				}
+				return map[string]any{"tries": out, "recovery": said}, nil
+			}},
+		{Name: RecoverTriesTool,
+			Description: "Run the recovery of the open tries now: the indexer lists them through the checker's checker_tries, writes the candidate of each " +
+				"whole try that waits or runs and deletes the candidate of a try no longer listed. It runs by itself at the indexer's start; when it failed " +
+				"(indexer_try_candidates says recovery not done, since when and why) this runs it again. A hand act: who and why are said in the journal.",
+			Input: map[string]any{"type": "object", "required": []string{"why"}, "properties": map[string]any{
+				"why": map[string]any{"type": "string", "description": "why it is run now, in plain words"}}},
+			Run: func(args map[string]any) (any, error) {
+				why, _ := args["why"].(string)
+				if strings.TrimSpace(why) == "" {
+					return nil, fmt.Errorf("say why: a hand act is said in the journal")
+				}
+				data, err := json.Marshal(TakeInAsk{V: 1, RecoverTries: true, Why: strings.TrimSpace(why), By: stdio.CallerOf(args), At: now().UTC()})
+				if err != nil {
+					return nil, err
+				}
+				a, err := ask("tries.recover."+now().UTC().Format("20060102T150405.000000000"), data)
+				if err != nil {
+					return nil, err
+				}
+				return a.Result, nil
+			}},
+		{Name: DropTryCandidateTool,
+			Description: "Drop a group try's candidate by hand (the indexer deletes it itself when the try ends): for a candidate left for a try that " +
+				"is gone, or to make the indexer write it again from the previews at the try's next change. A hand act: who and why are said in the journal.",
+			Input: map[string]any{"type": "object", "required": []string{"try", "why"}, "properties": map[string]any{
+				"try": map[string]any{"type": "string", "description": "the try's id, try-<digits>"},
+				"why": map[string]any{"type": "string", "description": "why it is dropped, in plain words"}}},
+			Run: func(args map[string]any) (any, error) {
+				id, _ := args["try"].(string)
+				why, _ := args["why"].(string)
+				id = strings.TrimSpace(id)
+				if !IsTryGroup(id) || strings.TrimSpace(why) == "" {
+					return nil, fmt.Errorf("name the try (try-<digits>) and say why")
+				}
+				data, err := json.Marshal(TakeInAsk{V: 1, TryCandidate: id, Drop: true, Why: strings.TrimSpace(why), By: stdio.CallerOf(args), At: now().UTC()})
+				if err != nil {
+					return nil, err
+				}
+				a, err := ask("try-candidate.drop."+id, data)
+				if err != nil {
+					return nil, err
+				}
+				return a.Result, nil
+			}},
+	}
+}
@@ -72,7 +72,10 @@ func (ix *Indexer) ApplyPreview(ctx context.Context, key string, value []byte, d
 	if !ix.PutPreview(key, value, deleted) {
 		return nil
 	}
-	return ix.RecomputeCandidates(ctx)
+	if err := ix.RecomputeCandidates(ctx); err != nil {
+		return err
+	}
+	return ix.WriteTryCandidates(ctx) // a try that waited for this preview gets its candidate
 }

 // RecomputeCandidates writes again every candidate whose pull requests' fingerprints, from the previews held, are no longer
@@ -3,10 +3,17 @@ package index
 import (
 	"context"
 	"encoding/json"
+	"errors"
+	"fmt"
 	"os"
+	"runtime"
+	"slices"
 	"strings"
 	"testing"
+	"time"

+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
+	"git.novox.be/novox/mesh-delivery/sdk/tryevent"
 	"git.novox.be/novox/mesh-sdk/go/delivery"

 	"mesh-delivery-indexer/internal/fingerprint"
@@ -38,7 +45,7 @@ func avahiOnTools(t *testing.T) string {
 }

 // avahiPull is the pull message of the catalogue's pull request 301 touching avahi, with its manifest.
-func avahiPull(t *testing.T, head string) delivery.Forge {
+func avahiPull(t *testing.T, head string) forgemsg.Forge {
 	t.Helper()
 	f := manifestPull(t, 301, head, avahiOnTools(t))
 	f.Manifests = map[string]string{"modules/avahi": avahiOnTools(t)}
@@ -181,6 +188,256 @@ func TestAPreviewHeardBeforeItsPullRequestGivesTheFingerprintWhenTheCandidateIsW
 	if got := fpOf(t, cands); got.FP2 != "" || got.None2 != NoneNoPreview {
 		t.Errorf("a new head: %+v, want no preview", got)
 	}
+	// Issue 1921: a whole group try has no pull request, yet the indexer writes its candidate from the checker's try events and
+	// the previews its fetch wrote (number 0, the heads hash of its members), keeps it apart from the pull requests' candidates,
+	// and deletes it when the try ends. Its manifests are judged with the seat definitions its members carry, in one locked
+	// pass, whether the contracts module's manifest changed or only its seat.json did (the wait is bounded: a lock held twice
+	// would show as a failure here, not as a stuck run).
+	for _, row := range []struct {
+		name      string
+		unchanged bool // the contracts module's module.json is the trunk's: only its definitions changed
+	}{
+		{name: "a changed manifest that carries definitions"},
+		{name: "an unchanged manifest that carries definitions", unchanged: true},
+	} {
+		t.Run("a group try's candidate: "+row.name, func(t *testing.T) {
+			ix, mods, cands := previewBed(t, true)
+			ctx := context.Background()
+			ix.Verdicts = newMem()
+			var changed map[string]any
+			if err := json.Unmarshal([]byte(catalogueManifest(t, "avahi")), &changed); err != nil {
+				t.Fatal(err)
+			}
+			changed["build"] = map[string]any{"artifacts": []any{map[string]any{"name": "go-seats", "kind": "package", "language": "go", "paths": []any{"go"}, "generated-from": "defs"}}}
+			raw, _ := json.Marshal(changed)
+			pv := avahiPreview(t, trunkNow, h1)
+			pm := delivery.PreviewModule{Tree: "tree-avahi", Manifest: delivery.ManifestDigest(raw), Locks: map[string]string{"go.sum": avahiGoSum}}
+			if row.unchanged {
+				m, found := moduleOf(t, mods, "avahi")
+				_ = found
+				pm.Manifest = m.Manifest
+				key, _ := delivery.ManifestsKey(m.Manifest)
+				data, _ := delivery.EncodeManifest(delivery.Manifest{Module: "avahi", JSON: string(raw)})
+				if _, _, _, err := ix.Manifests.Get(ctx, key); err != nil {
+					t.Fatal(err)
+				}
+				_ = ix.Manifests.(*memStore).Update(ctx, key, data, ix.Manifests.(*memStore).revs[key])
+			}
+			pv.Modules["modules/avahi"] = pm
+			ix.Read = func(_ context.Context, _, _, dir string) (RepoRead, error) {
+				return RepoRead{Manifests: map[string]string{dir: string(raw)}}, nil
+			}
+			listed := 0
+			ix.Files = func(_ context.Context, _, commit string, dirs []string) (map[string]map[string]string, error) {
+				listed++
+				if commit != h1 || !slices.Equal(dirs, []string{"modules/avahi/defs/seats"}) {
+					t.Errorf("listed %v at %s, want the member's head", dirs, commit)
+				}
+				return map[string]map[string]string{dirs[0]: {"node-engine/seat.json": "1"}}, nil
+			}
+			ix.ReadFile = func(_ context.Context, _, _, p string) ([]byte, error) {
+				switch p {
+				case "modules/avahi/defs/seats/node-engine/seat.json":
+					return []byte(`{"format":1,"seat":"node-engine","scope":"node","includes":["reads"]}`), nil
+				case "modules/avahi/defs/parts/reads.json":
+					return []byte(`{"format":1,"part":"reads","verbs":[{"name":"try-verb"}]}`), nil
+				}
+				return nil, nil
+			}
+			started := `{"id":"try-7"}`
+			_ = started
+			members := []TryMember{{Repository: catalogueRepo, Head: h1, Trunk: trunkNow}}
+			held := func() []string { k, _ := cands.Keys(ctx); return k }
+			if err := ix.StartTry(ctx, "try-7", members); err != nil || len(held()) != 0 {
+				t.Fatalf("a try before its preview: %v, candidates %v", err, held())
+			}
+			done := make(chan struct{})
+			go func() { defer close(done); applyPreview(t, ix, pv) }()
+			select {
+			case <-done:
+			case <-time.After(10 * time.Second):
+				panic("writing the try's candidate hangs: the seat lock is held twice (a locked pass cannot be left by t.Fatal: the lock stays held)")
+			}
+			if listed == 0 {
+				t.Error("the member's definitions were not read")
+			}
+			key, _ := delivery.CandidatesKey("try-7")
+			rawc, _, found, _ := cands.Get(ctx, key)
+			if !found {
+				t.Fatalf("no candidate for the try after its preview: %v", held())
+			}
+			c, err := delivery.DecodeCandidate(rawc)
+			pull := delivery.CandidatePull{}
+			if len(c.Pulls) == 1 {
+				pull = c.Pulls[0]
+			}
+			if row.unchanged {
+				if err != nil || c.Group != "try-7" || len(pull.Modules) != 0 {
+					t.Fatalf("candidate = %+v, %v, want the try's group with no module touched", c, err)
+				}
+			} else if err != nil || c.Group != "try-7" || pull.Number != 0 || pull.Head.Head != h1 || pull.Fps["avahi"].Manifest == "" { // no fingerprint asserted: this mesh-sdk pin does not read generated-from yet
+				t.Fatalf("candidate = %+v, %v, want one pull of number 0 with avahi's manifest", c, err)
+			}
+			if err := ix.Apply(ctx, forgemsg.Forge{Kind: forgemsg.ForgeOpen}); err != nil || len(held()) != 1 {
+				t.Errorf("the open message left %v (%v), want the try's candidate alone", held(), err)
+			}
+			// The tools: one reads the candidates held for tries, one drops by an ask the indexer answers.
+			asks := func(key string, value []byte) (TakeInAsk, error) {
+				a, err := DecodeTakeIn(value)
+				r := ix.DropTryCandidate(ctx, a.TryCandidate, a.By, a.Why)
+				a.Result = &r
+				return a, err
+			}
+			recovery := newMem()
+			ix.TryRecovery = recovery
+			tools := TryCandidateTools(cands, recovery, asks, time.Now)
+			if out, err := tools[0].Run(map[string]any{}); err != nil || len(out.(map[string]any)["tries"].([]delivery.Candidate)) != 1 {
+				t.Errorf("%s = %v, %v, want the try's candidate", tools[0].Name, out, err)
+			}
+			if _, err := tools[2].Run(map[string]any{"try": "feat/x", "why": "w"}); err == nil {
+				t.Error("a branch was dropped as a try")
+			}
+			if out, err := tools[2].Run(map[string]any{"try": "try-7", "why": "by hand"}); err != nil || !out.(*TakenIn).Stored || len(held()) != 0 {
+				t.Errorf("drop = %v, %v, candidates %v", out, err, held())
+			}
+			// The start recovered from the checker's tool: an open whole try is written again, one the checker no longer
+			// lists is deleted, and a try narrowed to a level is none.
+			ix.OpenTries = func(context.Context) ([]tryevent.Open, error) {
+				return []tryevent.Open{{ID: "try-7", Whole: true, Members: []tryevent.Member{{Repository: catalogueRepo, Head: h1, Trunk: trunkNow}}},
+					{ID: "try-8", Whole: false, Members: []tryevent.Member{{Repository: catalogueRepo, Head: h2, Trunk: trunkNow}}}}, nil
+			}
+			if err := ix.RecoverTries(ctx); err != nil || len(held()) != 1 {
+				t.Fatalf("recovered: %v, candidates %v, want try-7's alone", err, held())
+			}
+			ix.OpenTries = func(context.Context) ([]tryevent.Open, error) { return nil, nil }
+			if err := ix.RecoverTries(ctx); err != nil || len(held()) != 0 {
+				t.Errorf("recovered with no open try: %v, candidates %v, want none", err, held())
+			}
+			// A recovery whose call fails is loud and deletes nothing: the candidate stays, indexer_try_candidates says recovery not
+			// done since when and why, and the next try event runs the recovery again, which clears it; the tool runs it by hand.
+			if err := ix.StartTry(ctx, "try-7", members); err != nil || len(held()) != 1 {
+				t.Fatalf("started: %v, candidates %v", err, held())
+			}
+			ix.OpenTries = func(context.Context) ([]tryevent.Open, error) {
+				return nil, errors.New("checker_tries does not answer")
+			}
+			if err := ix.RecoverTries(ctx); err == nil || len(held()) != 1 {
+				t.Fatalf("a failed call: %v, candidates %v, want the error and the candidate kept", err, held())
+			}
+			if out, err := tools[0].Run(map[string]any{}); err != nil || !strings.Contains(out.(map[string]any)["recovery"].(map[string]any)["says"].(string), "recovery not done, since") ||
+				!strings.Contains(out.(map[string]any)["recovery"].(map[string]any)["says"].(string), "checker_tries does not answer") {
+				t.Errorf("%s = %v, %v, want recovery not done with since and why", tools[0].Name, out, err)
+			}
+			ix.OpenTries = func(context.Context) ([]tryevent.Open, error) { return nil, nil }
+			if err := ix.StartTry(ctx, "try-11", members); err != nil || len(held()) != 1 || held()[0] != "try-11" {
+				t.Fatalf("a try event after a failed recovery: %v, candidates %v, want the recovery run (try-7 not listed, gone) and try-11 written", err, held())
+			}
+			if out, _ := tools[0].Run(map[string]any{}); out.(map[string]any)["recovery"].(map[string]any)["done"] != true {
+				t.Errorf("recovery still said not done after a success: %v", out)
+			}
+			ix.OpenTries = func(context.Context) ([]tryevent.Open, error) { return nil, errors.New("down") }
+			recoverAsk := func(key string, value []byte) (TakeInAsk, error) {
+				a, err := DecodeTakeIn(value)
+				r := ix.RecoverTriesByHand(ctx, a.By, a.Why)
+				a.Result = &r
+				return a, err
+			}
+			byHand := TryCandidateTools(cands, recovery, recoverAsk, time.Now)
+			if out, err := byHand[1].Run(map[string]any{"why": "the checker was replaced"}); err != nil || out.(*TakenIn).Stored || !strings.Contains(out.(*TakenIn).Answer, "recovery not done") {
+				t.Errorf("%s with the checker down = %v, %v", byHand[1].Name, out, err)
+			}
+			ix.OpenTries = func(context.Context) ([]tryevent.Open, error) { return nil, nil }
+			if out, err := byHand[1].Run(map[string]any{"why": "the checker is back"}); err != nil || !out.(*TakenIn).Stored || len(held()) != 0 {
+				t.Errorf("%s = %v, %v, candidates %v, want it recovered (try-11 not listed)", byHand[1].Name, out, err, held())
+			}
+			if err := ix.StartTry(ctx, "try-7", members); err != nil {
+				t.Fatal(err)
+			}
+			// ADR 0638 §3, §4: the consumer exists before the call, so what happens between the call and the hearing is heard after
+			// it. A try the call listed and whose start is then heard gets one candidate; a try started after the list gets one; a
+			// try that ended during the call, listed as open, leaves none once its end is heard.
+			ix.OpenTries = func(context.Context) ([]tryevent.Open, error) {
+				return []tryevent.Open{{ID: "try-7", Whole: true, Members: []tryevent.Member{{Repository: catalogueRepo, Head: h1, Trunk: trunkNow}}},
+					{ID: "try-9", Whole: true, Members: []tryevent.Member{{Repository: catalogueRepo, Head: h1, Trunk: trunkNow}}}}, nil
+			}
+			if err := ix.RecoverTries(ctx); err != nil {
+				t.Fatal(err)
+			}
+			for _, step := range []struct {
+				what string
+				do   func() error
+				want int
+			}{
+				{"the start heard after the call, of a try the call listed", func() error { return ix.StartTry(ctx, "try-7", members) }, 2},
+				{"a start after the list", func() error { return ix.StartTry(ctx, "try-10", members) }, 3},
+				{"the end heard of a try ended during the call", func() error { return ix.EndTry(ctx, "try-9") }, 2},
+			} {
+				if err := step.do(); err != nil || len(held()) != step.want {
+					t.Fatalf("%s: %v, candidates %v, want %d", step.what, err, held(), step.want)
+				}
+			}
+			for _, id := range []string{"try-10"} {
+				if err := ix.EndTry(ctx, id); err != nil {
+					t.Fatal(err)
+				}
+			}
+			if err := ix.StartTry(ctx, "try-7", members); err != nil || len(held()) != 1 {
+				t.Fatalf("started again: %v, candidates %v", err, held())
+			}
+			if err := ix.EndTry(ctx, "try-7"); err != nil || len(held()) != 0 {
+				t.Errorf("an ended try: %v, candidates %v, want none", err, held())
+			}
+			// The hand recovery never overlaps a try event: a start heard while the call to the checker is out writes its candidate
+			// before or after the sweep, never between the call and the sweep (which would delete it, the try not being listed).
+			startDone := make(chan error, 1)
+			ix.OpenTries = func(context.Context) ([]tryevent.Open, error) {
+				go func() { startDone <- ix.StartTry(ctx, "try-12", members) }()
+				for i := 0; i < 2000 && len(held()) == 0; i++ {
+					runtime.Gosched() // lets the start write if nothing holds it back
+				}
+				return nil, nil
+			}
+			if r := ix.RecoverTriesByHand(ctx, "lead", "a test"); !r.Stored {
+				t.Fatalf("the hand recovery = %+v", r)
+			}
+			if err := <-startDone; err != nil || len(held()) != 1 || held()[0] != "try-12" {
+				t.Errorf("a start heard during the hand recovery: %v, candidates %v, want try-12 kept", err, held())
+			}
+		})
+	}
+	// Issue 1921: a head whose tree lacks the directory asked is asked once, however many passes read it, until the head changes;
+	// any other failure (the forge does not answer) is asked again at every pass and said once per head.
+	for _, row := range []struct {
+		name          string
+		err           error
+		askedAfterTwo int // the same head read twice
+		askedAfterNew int // then another head
+		linesAfterNew int
+	}{
+		{"the directory is not in the tree", fmt.Errorf("listing: %w", ErrNotInTree), 1, 2, 2},
+		{"the forge does not answer", errors.New("the forge does not answer"), 2, 3, 2},
+	} {
+		t.Run("a failing head: "+row.name, func(t *testing.T) {
+			ix, _, _ := previewBed(t, false)
+			var logs strings.Builder
+			ix.Logf = func(format string, args ...any) { logs.WriteString(fmt.Sprintf(format, args...) + "\n") }
+			asked := 0
+			ix.Files = func(context.Context, string, string, []string) (map[string]map[string]string, error) {
+				asked++
+				return nil, row.err
+			}
+			held := map[string]delivery.Module{"x": {Inputs2: &delivery.KeptInputs2{Packages: []string{"git.novox.be/novox/mesh-sdk/go"}}}}
+			for pass, head := range []string{h1, h1, h2} {
+				ix.candidatePublished(context.Background(), map[string]string{"novox/mesh-sdk": head}, held)
+				if pass == 1 && (asked != row.askedAfterTwo || strings.Count(logs.String(), "its packages are not read") != 1) {
+					t.Fatalf("after two passes over %s: asked %d (want %d), journal %q: want one line", head, asked, row.askedAfterTwo, logs.String())
+				}
+			}
+			if asked != row.askedAfterNew || strings.Count(logs.String(), "its packages are not read") != row.linesAfterNew {
+				t.Errorf("asked %d (want %d), journal %q (want %d lines)", asked, row.askedAfterNew, logs.String(), row.linesAfterNew)
+			}
+		})
+	}
 }

 func TestAPreviewNamingNoManifestOfTheModulesDirectoryGivesAReason(t *testing.T) {
@@ -7,6 +7,7 @@ import (
 	"slices"
 	"strings"

+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 )

@@ -125,7 +126,7 @@ func (ix *Indexer) indexAt(ctx context.Context, r Registration, force, reread bo
 		t.why = fmt.Sprintf("the manifest at %q of %s at %s names the module %q", dir, repository, commit, name)
 		return t, nil
 	}
-	f := delivery.Forge{V: delivery.Version, Kind: delivery.ForgeMerged, Repository: repository, Merge: commit, Root: read.Root,
+	f := forgemsg.Forge{V: delivery.Version, Kind: forgemsg.ForgeMerged, Repository: repository, Merge: commit, Root: read.Root,
 		Trees:     map[string]string{dir: read.Trees[dir]},
 		Manifests: map[string]string{dir: raw}}
 	if l := read.Locks[dir]; len(l) > 0 {
@@ -396,7 +397,7 @@ func (ix *Indexer) TakeInRepository(ctx context.Context, repository string) Take
 		out.Answer = "the modules state cannot be read: " + err.Error()
 		return out
 	}
-	f := delivery.Forge{V: delivery.Version, Kind: delivery.ForgeMerged, Repository: out.Repository, Merge: head}
+	f := forgemsg.Forge{V: delivery.Version, Kind: forgemsg.ForgeMerged, Repository: out.Repository, Merge: head}
 	if _, err := ix.ApplyMessage(ctx, f); err != nil {
 		out.Answer = fmt.Sprintf("the merge of %s at %.12s could not be taken in: %v", repository, head, err)
 		return out
@@ -0,0 +1,154 @@
+package index
+
+// The seat definitions a revision carries (novox/hq ADR 0633 §1, ADR 0635 §3, ADR 0636 §4): when a take-in works out which
+// indexer a revision names, the manifests it writes are judged against the seats of that revision, never against the
+// list this program was built with, since the indexer the revision names may serve or invoke what the revision's
+// definitions add (a verb of a seat, an event). They are read from the merges' trees: each contracts module a merge's
+// manifests name (a package artifact with `generated-from`) holds `seats/<seat>/seat.json` and the `parts/` they
+// include, read through the forge's listing and get-file tools. A delivery group's merges are one revision, so a
+// group's members' definitions are read together.
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"maps"
+	"path"
+	"slices"
+	"strings"
+
+	"git.novox.be/novox/mesh-sdk/go/catalogue"
+
+	"mesh-delivery-indexer/judge"
+)
+
+// definitionsDir is the directory of a contracts module's definitions that the module.json at dir names, from the first
+// package artifact naming `generated-from`: ok is false for a module that is no contracts module. A manifest that does
+// not decode is none here: the judge says why it is refused.
+func definitionsDir(dir, manifest string) (string, bool) {
+	var m struct {
+		Build struct {
+			Artifacts []struct {
+				GeneratedFrom string `json:"generated-from"`
+			} `json:"artifacts"`
+		} `json:"build"`
+	}
+	if json.Unmarshal([]byte(manifest), &m) != nil {
+		return "", false
+	}
+	for _, a := range m.Build.Artifacts {
+		if a.GeneratedFrom == "" {
+			continue
+		}
+		base := dir
+		if base == "." || base == "/" {
+			base = ""
+		}
+		return path.Clean(path.Join(base, a.GeneratedFrom)), true
+	}
+	return "", false
+}
+
+// revisionSeats are the seats of the definitions the ready merges carry, read at their merge commits, the newest merge
+// of a repository governing; none where the indexer has no forge reader. A read the forge does not answer is an error
+// (the take-in is tried again); a definition that does not parse is said and left out, as the indexer that keeps it
+// would say it unparsed.
+func (ix *Indexer) revisionSeats(ctx context.Context, ready []PendingEntry) ([]catalogue.Seat, error) {
+	if ix.ReadFile == nil || ix.Files == nil {
+		return nil, nil
+	}
+	var defs []judge.Definition
+	for _, e := range ready {
+		if e.Covered || e.Forge.Merge == "" {
+			continue
+		}
+		for _, dir := range slices.Sorted(maps.Keys(e.Forge.Manifests)) {
+			defsDir, ok := definitionsDir(dir, e.Forge.Manifests[dir])
+			if !ok {
+				continue
+			}
+			got, err := ix.readDefinitions(ctx, e.Forge.Repository, e.Forge.Merge, defsDir)
+			if err != nil {
+				return nil, err
+			}
+			defs = append(defs, got...)
+		}
+	}
+	seats, err := judge.Seats(defs)
+	if err != nil {
+		return nil, err
+	}
+	return seats, nil
+}
+
+// readDefinitions reads the definitions under a contracts module's definitions directory at a commit, resolved with their
+// parts.
+func (ix *Indexer) readDefinitions(ctx context.Context, repository, commit, defsDir string) ([]judge.Definition, error) {
+	file := func(p string) ([]byte, error) {
+		if defsDir != "." && defsDir != "" {
+			p = defsDir + "/" + p
+		}
+		raw, err := ix.ReadFile(ctx, repository, commit, p)
+		if err != nil {
+			return nil, fmt.Errorf("reading %s of %s at %.12s: %w", p, repository, commit, err)
+		}
+		return raw, nil
+	}
+	dir := path.Join(defsDir, "seats")
+	if defsDir == "." || defsDir == "" {
+		dir = "seats"
+	}
+	listed, err := ix.Files(ctx, repository, commit, []string{dir})
+	if err != nil {
+		return nil, fmt.Errorf("listing %s of %s at %.12s: %w", dir, repository, commit, err)
+	}
+	parts := map[string]judge.Part{}
+	var out []judge.Definition
+	for _, p := range slices.Sorted(maps.Keys(listed[dir])) {
+		seat, ok := strings.CutSuffix(p, "/seat.json")
+		if !ok || seat == "" || strings.Contains(seat, "/") {
+			continue
+		}
+		raw, err := file("seats/" + seat + "/seat.json")
+		if err != nil {
+			return nil, err
+		}
+		d, err := judge.ParseDefinition(raw)
+		if err == nil && d.Seat != seat {
+			err = fmt.Errorf("it names the seat %q, not %q", d.Seat, seat)
+		}
+		for _, name := range d.Includes {
+			if err != nil {
+				break
+			}
+			if _, have := parts[name]; have {
+				continue
+			}
+			praw, perr := file("parts/" + name + ".json")
+			if perr != nil {
+				return nil, perr
+			}
+			var part judge.Part
+			if praw == nil {
+				perr = errors.New("the commit holds no such part")
+			} else {
+				part, perr = judge.ParsePart(praw)
+			}
+			if perr != nil {
+				err = fmt.Errorf("its part %s: %w", name, perr)
+				break
+			}
+			parts[name] = part
+		}
+		if err == nil {
+			d, err = d.Resolve(parts)
+		}
+		if err != nil {
+			ix.logf("take-in: the seat definition seats/%s of %s at %.12s does not parse, so it is left out: %v", seat, repository, commit, err)
+			continue
+		}
+		out = append(out, d)
+	}
+	return out, nil
+}
@@ -51,6 +51,17 @@ func TestASourceRevisionStampsTheModulesOfTheRepositoriesHeadItNames(t *testing.
 }

 func TestAMergeHeardAfterTheSourceNamesItsHeadIsStampedWhenWritten(t *testing.T) { // 1344/AC1 (the source first)
+	// A source revision older than the one held is left (merged here from a test of its own, for the test budget).
+	t.Run("an older source revision is left", func(t *testing.T) {
+		ix, mods := modulesIndexer(t, rec(t, "build-1", "a", "novox/mesh-delivery", "modules/a", "main", "", "2026-10-19T09:00:00Z", aInputs))
+		ctx := context.Background()
+		_ = ix.Apply(ctx, mergedMsg("novox/mesh-delivery", map[string]string{"modules/a": "newtree"}))
+		_ = ix.ApplySource(ctx, 9, sourceOf("novox/mesh-delivery", merge))
+		_ = ix.ApplySource(ctx, 7, sourceOf("novox/mesh-delivery", merge))
+		if m, _ := moduleOf(t, mods, "a"); m.Src != 9 {
+			t.Errorf("module a Src = %d, want 9", m.Src)
+		}
+	})
 	ix, mods := modulesIndexer(t, rec(t, "build-1", "a", "novox/mesh-delivery", "modules/a", "main", "", "2026-10-19T09:00:00Z", aInputs))
 	ctx := context.Background()
 	if err := ix.ApplySource(ctx, 7, sourceOf("novox/mesh-delivery", merge)); err != nil {
@@ -93,14 +104,3 @@ func TestAMergeThatNoSourceRevisionNamesIsWrittenAsToday(t *testing.T) { // 1344
 		t.Errorf("module a = %+v, want the new merge with Src 0", m)
 	}
 }
-
-func TestASourceRevisionOlderThanTheOneHeldIsLeft(t *testing.T) {
-	ix, mods := modulesIndexer(t, rec(t, "build-1", "a", "novox/mesh-delivery", "modules/a", "main", "", "2026-10-19T09:00:00Z", aInputs))
-	ctx := context.Background()
-	_ = ix.Apply(ctx, mergedMsg("novox/mesh-delivery", map[string]string{"modules/a": "newtree"}))
-	_ = ix.ApplySource(ctx, 9, sourceOf("novox/mesh-delivery", merge))
-	_ = ix.ApplySource(ctx, 7, sourceOf("novox/mesh-delivery", merge))
-	if m, _ := moduleOf(t, mods, "a"); m.Src != 9 {
-		t.Errorf("module a Src = %d, want 9", m.Src)
-	}
-}
@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"regexp"
 	"strings"
 	"time"

@@ -33,11 +34,24 @@ type TakeInAsk struct {
 	// Judge asks the manifests to be judged again now (indexer_judge_again) instead of the module to be taken in.
 	Judge bool `json:"judge,omitempty"`
 	// Digest names, with Judge, the one manifest digest of the module to judge (indexer_judge with a digest).
-	Digest   string    `json:"digest,omitempty"`
-	By       string    `json:"by,omitempty"`
-	At       time.Time `json:"at"`
-	Result   *TakenIn  `json:"result,omitempty"`
-	Answered time.Time `json:"answered,omitzero"`
+	Digest string `json:"digest,omitempty"`
+	// Pending asks the wait under this take-in key to be taken in by hand (indexer_take_in_pending), or with Drop the
+	// one pending merge under it to be dropped (indexer_drop_pending), instead of a module (pending.go, ADR 0633 §5).
+	Pending string `json:"pending,omitempty"`
+	// Merge asks the merge of MergeRepository at this commit to be taken in by hand (indexer_take_in_merge): its merged message
+	// is asked of the forge bridge and run through the take-in as a delivered one, under its stream sequence Sequence.
+	Merge           string `json:"merge,omitempty"`
+	MergeRepository string `json:"merge-repository,omitempty"`
+	Sequence        uint64 `json:"sequence,omitempty"`
+	// TryCandidate asks the candidate of this try's group to be dropped (indexer_drop_try_candidate), trycandidates.go.
+	TryCandidate string `json:"try-candidate,omitempty"`
+	// RecoverTries asks the open tries' candidates to be recovered now (indexer_recover_tries).
+	RecoverTries bool      `json:"recover-tries,omitempty"`
+	Drop         bool      `json:"drop,omitempty"`
+	By           string    `json:"by,omitempty"`
+	At           time.Time `json:"at"`
+	Result       *TakenIn  `json:"result,omitempty"`
+	Answered     time.Time `json:"answered,omitzero"`
 }

 // Done says the ask is answered.
@@ -52,8 +66,8 @@ func DecodeTakeIn(data []byte) (TakeInAsk, error) {
 	if a.V != 1 {
 		return a, fmt.Errorf("a takeins value of version %d, not 1", a.V)
 	}
-	if a.Module == "" && a.Repository == "" {
-		return a, errors.New("a takeins value naming no module or repository")
+	if a.Module == "" && a.Repository == "" && a.Pending == "" && a.Merge == "" && a.TryCandidate == "" && !a.RecoverTries {
+		return a, errors.New("a takeins value naming no module, repository, pending wait, merge or try")
 	}
 	return a, nil
 }
@@ -82,3 +96,49 @@ func NewTakeInRepository(repository, why, by string, at time.Time) (string, []by
 	data, err := json.Marshal(TakeInAsk{V: 1, Repository: repository, Why: strings.TrimSpace(why), By: by, At: at.UTC()})
 	return "repository." + key, data, err
 }
+
+// TakeInMergeTool takes one merge in by hand, its merged message asked of the forge bridge (ADR 0633 §5, issue 1585).
+const TakeInMergeTool = "indexer_take_in_merge"
+
+var sha40 = regexp.MustCompile(`^[0-9a-f]{40}$`)
+
+// NewMergeAsk is the value indexer_take_in_merge writes: its key in takeins, `merge.<commit>`, and the value. sequence is
+// the merge's sequence on the forge bridge's stream, as indexer_heard names it: the pending merge is keyed by it, which
+// keeps the merge order.
+func NewMergeAsk(repository, merge string, sequence uint64, why, by string, at time.Time) (string, []byte, error) {
+	repository, merge = strings.TrimSpace(repository), strings.TrimSpace(merge)
+	switch {
+	case !strings.Contains(repository, "/"):
+		return "", nil, errors.New("name the repository as owner/name (repository)")
+	case !sha40.MatchString(merge):
+		return "", nil, errors.New("name the merge commit, 40 hex digits (merge)")
+	case sequence == 0:
+		return "", nil, errors.New("name the merge's sequence on the forge bridge's stream (sequence), as indexer_heard names it")
+	case strings.TrimSpace(why) == "":
+		return "", nil, errors.New("say why (why): a hand act is said in the journal")
+	}
+	data, err := json.Marshal(TakeInAsk{V: 1, Merge: merge, MergeRepository: repository, Sequence: sequence, Why: strings.TrimSpace(why), By: by, At: at.UTC()})
+	return "merge." + merge, data, err
+}
+
+// NewPendingAsk is the value indexer_take_in_pending (drop false) or indexer_drop_pending (drop true) writes: its key
+// in takeins, `pending.<take-in|drop>.<key>`, and the value. key is a wait's key as indexer_pending names it, for a
+// drop one pending merge's.
+func NewPendingAsk(key, why, by string, drop bool, at time.Time) (string, []byte, error) {
+	key = strings.TrimSpace(key)
+	if !strings.HasPrefix(key, "m.") && !(strings.HasPrefix(key, "g.") && !drop) {
+		if drop {
+			return "", nil, errors.New("name the pending merge to drop by its key, m.<sequence>, as indexer_pending names it")
+		}
+		return "", nil, errors.New("name the wait to take in by its key, m.<sequence> or g.<group>, as indexer_pending names it")
+	}
+	if strings.TrimSpace(why) == "" {
+		return "", nil, errors.New("say why (why): a hand act on what waits is said in the journal and on its take-in event")
+	}
+	act := "take-in"
+	if drop {
+		act = "drop"
+	}
+	data, err := json.Marshal(TakeInAsk{V: 1, Pending: key, Drop: drop, Why: strings.TrimSpace(why), By: by, At: at.UTC()})
+	return "pending." + act + "." + key, data, err
+}
@@ -8,6 +8,7 @@ import (
 	"slices"
 	"time"

+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 	"git.novox.be/novox/mesh-sdk/go/process"
 )
@@ -19,13 +20,13 @@ import (
 // say keeps the key as it is and says so.

 // writeTaken writes the repository's taken key for the merge f carries, unless it names that merge or a later one.
-func (ix *Indexer) writeTaken(ctx context.Context, f delivery.Forge) error {
+func (ix *Indexer) writeTaken(ctx context.Context, f forgemsg.Forge) error {
 	return ix.writeTakenKnown(ctx, f, "")
 }

 // writeTakenKnown is writeTaken where the merge is known not to be older than notOlder (lateMerge asked it, issue 1126): a
 // key naming that merge is written over without asking the forge again.
-func (ix *Indexer) writeTakenKnown(ctx context.Context, f delivery.Forge, notOlder string) error {
+func (ix *Indexer) writeTakenKnown(ctx context.Context, f forgemsg.Forge, notOlder string) error {
 	if ix.Taken == nil || f.Merge == "" {
 		return nil
 	}
@@ -101,7 +102,7 @@ func (ix *Indexer) FillTaken(ctx context.Context) error {
 		}
 	}
 	for _, repository := range slices.Sorted(maps.Keys(pending)) {
-		err := ix.writeTaken(ctx, delivery.Forge{Repository: repository, Merge: pending[repository]})
+		err := ix.writeTaken(ctx, forgemsg.Forge{Repository: repository, Merge: pending[repository]})
 		if err == nil {
 			ix.mu.Lock()
 			if ix.untaken[repository] == pending[repository] {
@@ -78,12 +78,22 @@ func (ix *Indexer) PutToolchain(module, key string, value []byte, deleted bool)
 }

 // ApplyToolchain takes one change of a build module's toolchains in (PutToolchain) and, when the language's toolchain
-// changed, writes the modules again that it moves (Recompute). The same version and recipe seen again writes nothing.
+// changed, writes the modules again that it moves and evaluates pending again (ToolchainReported). The same version and
+// recipe seen again writes nothing.
 func (ix *Indexer) ApplyToolchain(ctx context.Context, module, key string, value []byte, deleted bool) error {
 	if !ix.PutToolchain(module, key, value, deleted) {
 		return nil
 	}
-	return ix.Recompute(ctx)
+	return ix.ToolchainReported(ctx)
+}
+
+// ToolchainReported is what a changed toolchain moves: the modules written again (Recompute), then pending evaluated
+// again (PendingAgain), since the indexer build a pending revision names is a fingerprint the toolchain is part of.
+func (ix *Indexer) ToolchainReported(ctx context.Context) error {
+	if err := ix.Recompute(ctx); err != nil {
+		return err
+	}
+	return ix.PendingAgain(ctx)
 }

 // agreed is the toolchain of each language every reporting node agrees on, or why there is none.
@@ -10,6 +10,7 @@ import (
 	"testing"
 	"time"

+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 	"git.novox.be/novox/mesh-sdk/go/process"

@@ -91,7 +92,7 @@ func newFormIndexer(t *testing.T, mods ...mod) (*Indexer, *memStore) {
 }

 // newFormIndexerUnmerged is the indexer and the catalogue merge of these modules, not yet applied.
-func newFormIndexerUnmerged(t *testing.T, mods ...mod) (*Indexer, *memStore, delivery.Forge) {
+func newFormIndexerUnmerged(t *testing.T, mods ...mod) (*Indexer, *memStore, forgemsg.Forge) {
 	t.Helper()
 	var recs [][2]any
 	trees, manifests := map[string]string{}, map[string]string{}
@@ -468,7 +469,7 @@ func TestAModuleKeepsTheToolchainsItsFingerprintWasComputedWith(t *testing.T) {
 	tools, _ := moduleOf(t, mods, "mesh-tools")
 	sdkMerge := func(commit, tree string) delivery.Module {
 		t.Helper()
-		f := delivery.Forge{V: delivery.Version, Kind: delivery.ForgeMerged, Repository: "novox/mesh-sdk", Branch: "feat/x", Number: 3, Head: h1,
+		f := forgemsg.Forge{V: delivery.Version, Kind: forgemsg.ForgeMerged, Repository: "novox/mesh-sdk", Branch: "feat/x", Number: 3, Head: h1,
 			Merge: commit, Root: tree, Trees: map[string]string{"": tree}, Manifests: map[string]string{"": `{"module":"mesh-sdk","version":"1"}`}}
 		if err := ix.Apply(context.Background(), f); err != nil {
 			t.Fatal(err)
@@ -0,0 +1,439 @@
+package index
+
+// **A group try's candidate** (issue 1921; novox/hq ADR 0593 §7): a try of several repositories at exact commits has no pull
+// request, so the forge bridge sends the indexer no message for it; yet the node-engine's compose-candidate and the checker's
+// manifest validator read the indexer's candidate of a group. The indexer therefore watches the checker's state tries (the
+// checker keeps it; this module reads it) and, for a try that is not narrowed to a level or to some tests, writes
+// `candidates.<try id>`: one pull per member (number 0), its modules and manifests taken from the merge preview the try's
+// fetch wrote, its manifests kept and judged with the seat definitions the members carry, as a take-in judges a revision's.
+// The fingerprints come with the previews (RecomputeCandidates). The candidate is deleted when the try ends. `try-<digits>`
+// is the reserved group name of a try: the bridge's open message never takes it out, and the checker never checks it.
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"path"
+	"regexp"
+	"slices"
+	"strings"
+	"time"
+
+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+)
+
+// TryCandidateTools: the tools that read, drop and recover a try's candidate.
+const (
+	TryCandidatesTool    = "indexer_try_candidates"
+	DropTryCandidateTool = "indexer_drop_try_candidate"
+	RecoverTriesTool     = "indexer_recover_tries"
+	// TryRecoveryState is the indexer's state of how the last recovery of the open tries went: the bucket
+	// mesh-delivery-indexer_try-recovery, one key (TryRecoveryKey).
+	TryRecoveryState  = "try-recovery"
+	TryRecoveryBucket = delivery.IndexerModule + "_" + TryRecoveryState
+	TryRecoveryKey    = "state"
+)
+
+// TryRecovery is the value of the try-recovery state: whether the candidates of the open tries were recovered at the
+// indexer's start or by hand, and when it began to fail, why.
+type TryRecovery struct {
+	V     int       `json:"v"`
+	Done  bool      `json:"done"`
+	Since time.Time `json:"since,omitzero"`
+	Why   string    `json:"why,omitempty"`
+	At    time.Time `json:"at"`
+}
+
+var tryGroupOK = regexp.MustCompile(`^try-[0-9]{1,20}$`)
+
+// IsTryGroup says a candidates key is the group of a try.
+func IsTryGroup(key string) bool { return tryGroupOK.MatchString(key) }
+
+// TryMember is one repository of a try: its exact commit and the trunk commit it is merged onto.
+type TryMember struct{ Repository, Head, Trunk string }
+
+// StartTry takes a whole try in, as the checker said it started (tryevent.Started): its members at their commits are kept, and
+// its candidate is written once every member's preview is held. The checker's state is never read (ADR 0596).
+func (ix *Indexer) StartTry(ctx context.Context, id string, members []TryMember) error {
+	ix.tryMu.Lock()
+	defer ix.tryMu.Unlock()
+	ix.retryRecovery(ctx)
+	return ix.startTry(ctx, id, members)
+}
+
+// retryRecovery runs the recovery again on a try event when the last one failed: the failure stays said until one succeeds.
+func (ix *Indexer) retryRecovery(ctx context.Context) {
+	if ix.recoveryFailed.Load() && ix.OpenTries != nil {
+		_ = ix.recoverNow(ctx)
+	}
+}
+
+func (ix *Indexer) startTry(ctx context.Context, id string, members []TryMember) error {
+	if !IsTryGroup(id) || len(members) == 0 {
+		return fmt.Errorf("%q with %d members is no try to start", id, len(members))
+	}
+	ix.mu.Lock()
+	if ix.tries == nil {
+		ix.tries = map[string][]TryMember{}
+	}
+	ix.tries[id] = slices.Clone(members)
+	ix.mu.Unlock()
+	return ix.writeTryCandidate(ctx, id)
+}
+
+// EndTry takes a try out, as the checker said it ended (tryevent.Ended), and deletes its candidate.
+func (ix *Indexer) EndTry(ctx context.Context, id string) error {
+	ix.tryMu.Lock()
+	defer ix.tryMu.Unlock()
+	ix.retryRecovery(ctx)
+	return ix.endTry(ctx, id)
+}
+
+func (ix *Indexer) endTry(ctx context.Context, id string) error {
+	ix.mu.Lock()
+	delete(ix.tries, id)
+	ix.mu.Unlock()
+	if !IsTryGroup(id) {
+		return nil
+	}
+	return ix.dropTryCandidate(ctx, id)
+}
+
+// RecoverTries is, at the indexer's start, what the events it missed would have said: the candidates of the tries that wait
+// or run now are written, and the candidate of a try the checker no longer lists is deleted. The checker's tool lists them
+// (OpenTries); its bucket is not read. Nothing to recover from when no part is wired to ask.
+//
+// A recovery that fails is said loudly and kept (the try-recovery state, read by indexer_try_candidates) until one succeeds:
+// the events are still heard after it, and indexer_recover_tries runs it again by hand.
+//
+// A recovery and a try event never overlap (tryMu): a sweep that deleted the candidate a start event wrote after the call to the
+// checker would leave a running try with none.
+func (ix *Indexer) RecoverTries(ctx context.Context) error {
+	ix.tryMu.Lock()
+	defer ix.tryMu.Unlock()
+	return ix.recoverNow(ctx)
+}
+
+func (ix *Indexer) recoverNow(ctx context.Context) error {
+	if ix.OpenTries == nil || ix.Store == nil {
+		return nil
+	}
+	err := ix.recoverTries(ctx)
+	ix.recoveryFailed.Store(err != nil)
+	ix.noteRecovery(ctx, err)
+	return err
+}
+
+// noteRecovery writes how a recovery went: failing keeps the time it began to fail, and the journal says it each time.
+func (ix *Indexer) noteRecovery(ctx context.Context, err error) {
+	now := ix.now()
+	r := TryRecovery{V: 1, Done: err == nil, At: now.UTC()}
+	if err != nil {
+		r.Why, r.Since = err.Error(), now.UTC()
+		ix.logf("RECOVERY OF THE TRIES NOT DONE: %v (the try candidates may be stale or missing until indexer_recover_tries or the next start succeeds)", err)
+	}
+	if ix.TryRecovery == nil {
+		return
+	}
+	for range writeTries {
+		cur, rev, found, gerr := ix.TryRecovery.Get(ctx, TryRecoveryKey)
+		if gerr != nil {
+			ix.logf("the try-recovery state cannot be read: %v", gerr)
+			return
+		}
+		if err != nil && found {
+			var was TryRecovery
+			if json.Unmarshal(cur, &was) == nil && !was.Done && !was.Since.IsZero() {
+				r.Since = was.Since
+			}
+		}
+		data, _ := json.Marshal(r)
+		var werr error
+		if found {
+			werr = ix.TryRecovery.Update(ctx, TryRecoveryKey, data, rev)
+		} else {
+			werr = ix.TryRecovery.Create(ctx, TryRecoveryKey, data)
+		}
+		if werr == nil {
+			return
+		}
+		if !errors.Is(werr, ErrConflict) {
+			ix.logf("the try-recovery state cannot be written: %v", werr)
+			return
+		}
+	}
+}
+
+// RecoverTriesByHand runs the recovery now (indexer_recover_tries), a hand act said in the journal.
+func (ix *Indexer) RecoverTriesByHand(ctx context.Context, by, why string) TakenIn {
+	r := TakenIn{Module: "tries"}
+	ix.logf("recovery of the tries asked by %s (%s)", by, why)
+	if ix.OpenTries == nil {
+		r.Answer = "the indexer is wired to list no open try: nothing to recover from"
+		return r
+	}
+	if err := ix.RecoverTries(ctx); err != nil {
+		r.Answer = "recovery not done: " + err.Error()
+		return r
+	}
+	r.Stored, r.Answer = true, "the candidates of the open tries are recovered"
+	return r
+}
+
+func (ix *Indexer) recoverTries(ctx context.Context) error {
+	open, err := ix.OpenTries(ctx)
+	if err != nil {
+		return fmt.Errorf("the open tries cannot be listed, so a missed try event is not recovered: %w", err)
+	}
+	live := map[string]bool{}
+	for _, o := range open {
+		if !o.Whole || len(o.Members) == 0 {
+			continue
+		}
+		live[o.ID] = true
+		var ms []TryMember
+		for _, m := range o.Members {
+			ms = append(ms, TryMember{m.Repository, m.Head, m.Trunk})
+		}
+		if err := ix.startTry(ctx, o.ID, ms); err != nil {
+			return err
+		}
+	}
+	keys, err := ix.Store.Keys(ctx)
+	if err != nil {
+		return err
+	}
+	for _, k := range keys {
+		if IsTryGroup(k) && !live[k] {
+			if err := ix.endTry(ctx, k); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
+// WriteTryCandidates writes the candidate of every live try that has none yet and whose previews are all there: after a
+// preview was written, the try that waited for it.
+func (ix *Indexer) WriteTryCandidates(ctx context.Context) error {
+	ix.mu.Lock()
+	ids := make([]string, 0, len(ix.tries))
+	for id := range ix.tries {
+		ids = append(ids, id)
+	}
+	ix.mu.Unlock()
+	slices.Sort(ids)
+	for _, id := range ids {
+		if err := ix.writeTryCandidate(ctx, id); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (ix *Indexer) dropTryCandidate(ctx context.Context, id string) error {
+	if ix.Store == nil {
+		return nil
+	}
+	key, err := delivery.CandidatesKey(id)
+	if err != nil {
+		return err
+	}
+	return write(ctx, ix.Store, key, func(_ []byte, found bool) ([]byte, bool, error) { return nil, found, nil })
+}
+
+// DropTryCandidate deletes a try's candidate by hand (indexer_drop_try_candidate); a live try gets it again at its next
+// change.
+func (ix *Indexer) DropTryCandidate(ctx context.Context, id, by, why string) TakenIn {
+	r := TakenIn{Module: id}
+	switch {
+	case !IsTryGroup(id):
+		r.Answer = id + " is no try's group, try-<digits>: nothing dropped"
+	default:
+		if err := ix.dropTryCandidate(ctx, id); err != nil {
+			r.Answer = "the candidate of " + id + " could not be dropped: " + err.Error()
+		} else {
+			r.Stored, r.Answer = true, "the candidate of "+id+" is dropped by "+by+" ("+why+")"
+			ix.logf("%s", r.Answer)
+		}
+	}
+	return r
+}
+
+// writeTryCandidate writes the candidate of a live try when it has none at its members' heads and every member's merge
+// preview is held.
+func (ix *Indexer) writeTryCandidate(ctx context.Context, id string) error {
+	if ix.Store == nil || ix.Read == nil {
+		return nil
+	}
+	ix.mu.Lock()
+	members := slices.Clone(ix.tries[id])
+	ix.mu.Unlock()
+	if len(members) == 0 {
+		return nil
+	}
+	key, err := delivery.CandidatesKey(id)
+	if err != nil {
+		return err
+	}
+	slices.SortFunc(members, func(a, b TryMember) int { return strings.Compare(a.Repository, b.Repository) })
+	heads := make([]delivery.Head, len(members))
+	for i, m := range members {
+		heads[i] = delivery.Head{Repository: m.Repository, Head: m.Head}
+	}
+	hash, err := delivery.HeadsHash(heads)
+	if err != nil {
+		return err
+	}
+	if value, _, found, err := ix.Store.Get(ctx, key); err == nil && found {
+		if c, err := delivery.DecodeCandidate(value); err == nil && c.HeadsHash == hash {
+			return nil // fingerprints follow the previews (RecomputeCandidates)
+		}
+	}
+	previews := make([]delivery.Preview, len(members))
+	for i, m := range members {
+		pk, err := delivery.PreviewKey(m.Repository, m.Head, m.Trunk)
+		if err != nil {
+			return fmt.Errorf("the try %s: %w", id, err)
+		}
+		ix.mu.Lock()
+		pv, ok := ix.previews[pk]
+		ix.mu.Unlock()
+		if !ok {
+			return nil // its fetch has not written the preview yet: this is called again when it does
+		}
+		previews[i] = pv
+	}
+	held, err := ix.heldModules(ctx)
+	if err != nil {
+		return err
+	}
+	pulls := make([]delivery.CandidatePull, len(members))
+	var entries []PendingEntry
+	over := map[string]string{}
+	for i, m := range members {
+		pull := delivery.CandidatePull{Head: heads[i], Modules: []string{}}
+		// defs are every module directory's manifest of the member at its head, the unchanged ones too: a contracts module whose
+		// seat.json changed while its module.json did not carries definitions all the same (ADR 0636 §4).
+		defs := map[string]string{}
+		for _, dir := range slices.Sorted(mapKeys(previews[i].Modules)) {
+			pm := previews[i].Modules[dir]
+			name, unchanged := "", false
+			for n, h := range held {
+				if delivery.SameRepository(h.Repository, m.Repository) && h.Path == forgeDir(dir) {
+					name, unchanged = n, h.Manifest == pm.Manifest
+					break
+				}
+			}
+			if unchanged {
+				if raw := ix.keptManifest(ctx, pm.Manifest); raw != "" {
+					defs[dir] = raw
+				}
+				continue // the manifest the trunk holds: the try does not touch the module
+			}
+			rr, err := ix.Read(ctx, m.Repository, m.Head, forgeDir(dir))
+			if err != nil {
+				return fmt.Errorf("the try %s: reading the manifest of %s at %.12s: %w", id, dir, m.Head, err)
+			}
+			raw := rr.Manifests[forgeDir(dir)]
+			if raw == "" {
+				ix.logf("the try %s: %s holds no manifest at %.12s, so no module of it is taken", id, dir, m.Head)
+				continue
+			}
+			module := manifestModule(raw)
+			if module == "" {
+				module = name
+			}
+			if module == "" {
+				module = path.Base(strings.Trim(dir, "/."))
+			}
+			digest, err := ix.keepManifest(ctx, module, raw)
+			if err != nil {
+				return err
+			}
+			if digest != pm.Manifest {
+				ix.logf("the try %s: the manifest of %s read at %.12s is not the one its preview names, left", id, dir, m.Head)
+				continue
+			}
+			if pull.Fps == nil {
+				pull.Fps = map[string]delivery.CandidateModule{}
+			}
+			pull.Modules = append(pull.Modules, module)
+			pull.Fps[module] = delivery.CandidateModule{Manifest: digest, None2: NoneNoPreview}
+			defs[dir] = raw
+			over[module] = digest
+		}
+		pulls[i] = pull
+		entries = append(entries, PendingEntry{Forge: forgemsg.Forge{Repository: m.Repository, Merge: m.Head, Manifests: defs}})
+	}
+	// The manifests are judged with the seat definitions the members carry (seatsof.go, ADR 0636 §4), in one pass that takes the
+	// seats. Their verdicts are the verdicts state's, keyed by the manifest's digest, as a pull request's candidate's are
+	// (judgeDigests in ApplyMessage): nothing reads them but the engines' composition of that digest and the module
+	// value of a trunk module with the same digest.
+	seats, err := ix.revisionSeats(ctx, entries)
+	if err != nil {
+		return fmt.Errorf("the try %s: reading the seat definitions of its members: %w", id, err)
+	}
+	ix.judgeDigestsWith(ctx, seats, over, "the try "+id)
+	c := delivery.Candidate{V: delivery.Version, Group: id, HeadsHash: hash, Pulls: pulls}
+	c.FPSet = delivery.FingerprintSet(c.Pulls)
+	ix.withPreviews(ctx, &c)
+	if err := ix.refuseDisagreement(c); err != nil {
+		return err
+	}
+	data, err := delivery.EncodeCandidate(c)
+	if err != nil {
+		return err
+	}
+	return write(ctx, ix.Store, key, func(_ []byte, _ bool) ([]byte, bool, error) { return data, false, nil })
+}
+
+// keptManifest is the text of the manifest the indexer keeps under a digest, or empty.
+func (ix *Indexer) keptManifest(ctx context.Context, digest string) string {
+	if ix.Manifests == nil || digest == "" {
+		return ""
+	}
+	key, err := delivery.ManifestsKey(digest)
+	if err != nil {
+		return ""
+	}
+	value, _, found, err := ix.Manifests.Get(ctx, key)
+	if err != nil || !found {
+		return ""
+	}
+	m, err := delivery.DecodeManifest(value)
+	if err != nil {
+		return ""
+	}
+	return m.JSON
+}
+
+func mapKeys[V any](m map[string]V) func(func(string) bool) {
+	return func(yield func(string) bool) {
+		for k := range m {
+			if !yield(k) {
+				return
+			}
+		}
+	}
+}
+
+// forgeDir is a preview's directory as the forge reader spells it: the root as "".
+func forgeDir(dir string) string {
+	if dir == "." || dir == "/" {
+		return ""
+	}
+	return strings.Trim(dir, "/")
+}
+
+// heldAt says the trunk holds a module of the repository in that directory.
+func heldAt(held map[string]delivery.Module, repository, dir string) bool {
+	for _, h := range held {
+		if delivery.SameRepository(h.Repository, repository) && h.Path == forgeDir(dir) {
+			return true
+		}
+	}
+	return false
+}
--- a/Show More
+++ b/Show More