diff --git a/modules/mesh-delivery-indexer/cmd/mesh-delivery-indexer/main.go b/modules/mesh-delivery-indexer/cmd/mesh-delivery-indexer/main.go
index bf432663..5d60a336 100644
--- a/modules/mesh-delivery-indexer/cmd/mesh-delivery-indexer/main.go
+++ b/modules/mesh-delivery-indexer/cmd/mesh-delivery-indexer/main.go
@@ -435,6 +435,7 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 		OwnBuild: ownBuildVia(calls.Call, cred.Node), OpenTries: openTriesVia(calls.Call), OwnBuildState: awaitedStore{b: ownBuildState}, TryRecovery: awaitedStore{b: tryRecovery}, Graph: awaitedStore{b: graph},
 		SeatDefinitions: awaitedStore{b: seatDefs}, ReadFile: readFileVia(calls.Call), SaySeatDefinition: saySeats,
 		Message: messageVia(calls.CallKept), Revisions: &busObjects{js: js, local: index.CatalogRevisionsObjects}, // Message a kept call: a read, called again through a transport fault (ADR 0668 §1)
+		SayCatalogRevision: sayCatalogRevision(conn, cred),
 		// 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{b: 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)},
diff --git a/modules/mesh-delivery-indexer/cmd/mesh-delivery-indexer/objects.go b/modules/mesh-delivery-indexer/cmd/mesh-delivery-indexer/objects.go
index abc08a3c..bb6ae703 100644
--- a/modules/mesh-delivery-indexer/cmd/mesh-delivery-indexer/objects.go
+++ b/modules/mesh-delivery-indexer/cmd/mesh-delivery-indexer/objects.go
@@ -3,13 +3,19 @@ package main
 import (
 	"bytes"
 	"context"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"sync"
+	"time"
 
+	"github.com/nats-io/nats.go"
 	"github.com/nats-io/nats.go/jetstream"
 
+	"git.novox.be/novox/mesh-delivery/contracts/go/seats/meshcatalog"
+
 	"git.novox.be/novox/mesh-sdk/go/catalogue"
+	"git.novox.be/novox/mesh-sdk/go/process"
 
 	"mesh-delivery-indexer/internal/index"
 )
@@ -34,8 +40,11 @@ func (b *busObjects) open(ctx context.Context) (jetstream.ObjectStore, error) {
 		return b.o, nil
 	}
 	o, err := b.js.ObjectStore(ctx, catalogue.ObjectsBucket(indexerModule, b.local))
+	if errors.Is(err, jetstream.ErrBucketNotFound) || errors.Is(err, jetstream.ErrStreamNotFound) {
+		return nil, fmt.Errorf("the object bucket %s is not on the bus yet (the grants part creates it from the manifest's objects): %w", b.local, process.ErrNotYet)
+	}
 	if err != nil {
-		return nil, fmt.Errorf("the object bucket %s is not open (the grants part creates it from the manifest's objects): %w", b.local, err)
+		return nil, fmt.Errorf("the object bucket %s is not open: %w", b.local, err)
 	}
 	b.o = o
 	return o, nil
@@ -107,3 +116,24 @@ func (b *busObjects) Fill(ctx context.Context) (int64, int64, error) {
 	}
 	return int64(st.Size()), info.CachedInfo().Config.MaxBytes, nil
 }
+
+// sayCatalogRevision publishes the seat mesh-catalog's event catalog-revision under the duplicate id of its kind and
+// number, so a revision said twice is heard once (design 47, Two graphs).
+func sayCatalogRevision(conn *nats.Conn, cred process.Account) func(context.Context, meshcatalog.CatalogRevisionEvent) error {
+	return func(_ context.Context, e meshcatalog.CatalogRevisionEvent) error {
+		data, err := json.Marshal(e)
+		if err != nil {
+			return err
+		}
+		msg := nats.NewMsg(seatEventSubject(meshcatalog.EventCatalogRevision))
+		id := fmt.Sprintf("%s-%s-%d%s", meshcatalog.EventCatalogRevision, e.Kind, e.Revision, e.Heads)
+		msg.Header.Set("x-event-id", id)
+		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.Header.Set(nats.MsgIdHdr, id)
+		msg.Data = data
+		return conn.PublishMsg(msg)
+	}
+}
diff --git a/modules/mesh-delivery-indexer/internal/index/candidates.go b/modules/mesh-delivery-indexer/internal/index/candidates.go
index 8e9c5b81..57d8f35d 100644
--- a/modules/mesh-delivery-indexer/internal/index/candidates.go
+++ b/modules/mesh-delivery-indexer/internal/index/candidates.go
@@ -100,6 +100,8 @@ type Indexer struct {
 	// Revisions is the object bucket catalog-revisions (catalog_revisions.go; design 47, Two graphs); nil keeps no
 	// catalog graph revision.
 	Revisions Objects
+	// SayCatalogRevision says the seat mesh-catalog's event catalog-revision for a revision kept; nil says nothing.
+	SayCatalogRevision func(ctx context.Context, e meshcatalog.CatalogRevisionEvent) error
 	// Graph is the module graph's state (GraphBucket, graph.go; novox/hq ADR 0603 §2); nil writes no graph.
 	Graph Store
 	// Files asks the forge for every blob under each directory at a commit, by directory then path relative to it, each
diff --git a/modules/mesh-delivery-indexer/internal/index/catalog_revisions.go b/modules/mesh-delivery-indexer/internal/index/catalog_revisions.go
index 3a457422..ccb52f58 100644
--- a/modules/mesh-delivery-indexer/internal/index/catalog_revisions.go
+++ b/modules/mesh-delivery-indexer/internal/index/catalog_revisions.go
@@ -5,10 +5,13 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"slices"
 	"strconv"
 	"strings"
 
 	"git.novox.be/novox/mesh-delivery/contracts/go/seats/meshcatalog"
+	"git.novox.be/novox/mesh-delivery/sdk/graph"
+	"git.novox.be/novox/mesh-sdk/go/process"
 )
 
 // The indexer's object bucket catalog-revisions (design 47, Two graphs; novox/hq ADR 0619 §2: declared in the old
@@ -118,3 +121,96 @@ func ReadRevision(ctx context.Context, o Objects, name string) (meshcatalog.Cata
 	}
 	return rev, entries, nil
 }
+
+// newestTrunk is the newest trunk revision the bucket keeps, its list only; none is a zero revision and false.
+func newestTrunk(ctx context.Context, o Objects) (meshcatalog.CatalogRevision, bool, error) {
+	names, err := o.Names(ctx)
+	if err != nil {
+		return meshcatalog.CatalogRevision{}, false, err
+	}
+	var newest int64
+	for _, n := range names {
+		if r, ok := TrunkRevisionOf(n); ok && r > newest {
+			newest = r
+		}
+	}
+	if newest == 0 {
+		return meshcatalog.CatalogRevision{}, false, nil
+	}
+	data, err := o.Get(ctx, "trunk."+strconv.FormatInt(newest, 10))
+	if err != nil {
+		return meshcatalog.CatalogRevision{}, false, err
+	}
+	var rev meshcatalog.CatalogRevision
+	if err := json.Unmarshal(data, &rev); err != nil {
+		return rev, false, fmt.Errorf("trunk.%d: %w", newest, err)
+	}
+	return rev, true, nil
+}
+
+// changedEntries are the modules whose entry differs between two revisions' lists, one gone or added included, by name.
+func changedEntries(before, after []meshcatalog.EntryRef) []string {
+	was := map[string]string{}
+	for _, r := range before {
+		was[r.Module] = r.Digest
+	}
+	var changed []string
+	for _, r := range after {
+		if d, ok := was[r.Module]; !ok || d != r.Digest {
+			changed = append(changed, r.Module)
+		}
+		delete(was, r.Module)
+	}
+	for m := range was {
+		changed = append(changed, m)
+	}
+	slices.Sort(changed)
+	return changed
+}
+
+// keepTrunkRevision keeps the catalog graph revision a merge's or a recompute's module graph makes (design 47, Two
+// graphs: a revision for each source revision taken in, and for a fingerprint moved with no merge), numbered after the
+// newest kept, and says catalog-revision; a graph whose entries are the newest revision's makes none. A revision not
+// kept is said in the log and returned, so the take-in that made it is not said taken.
+func (ix *Indexer) keepTrunkRevision(ctx context.Context, edges map[string]graphEdges, whole graph.Graph) error {
+	if ix.Revisions == nil {
+		return nil
+	}
+	entries := make(map[string]meshcatalog.CatalogEntry, len(edges))
+	for name, e := range edges {
+		entries[name] = CatalogEntryOf(name, e.cur, whole[name])
+	}
+	ix.mu.Lock()
+	src := int64(ix.source.rev)
+	ix.mu.Unlock()
+	newest, any, err := newestTrunk(ctx, ix.Revisions)
+	if errors.Is(err, process.ErrNotYet) {
+		ix.logf("catalog graph: no revision is kept: its objects %s are not on the bus yet", CatalogRevisionsObjects)
+		return nil
+	}
+	if err != nil {
+		ix.logf("catalog graph: no revision is kept: the newest is not read: %v", err)
+		return fmt.Errorf("the newest catalog graph revision: %w", err)
+	}
+	at := ix.now().UTC()
+	rev, objects, err := CatalogRevisionOf(meshcatalog.CatalogRevision{Revision: newest.Revision + 1, Kind: "trunk", Source: src, At: &at}, entries)
+	if err != nil {
+		return err
+	}
+	changed := changedEntries(newest.Entries, rev.Entries)
+	if any && len(changed) == 0 {
+		return nil
+	}
+	if err := KeepRevision(ctx, ix.Revisions, rev, objects); err != nil {
+		ix.logf("catalog graph: revision %d of source revision %d is not kept: %v", rev.Revision, src, err)
+		return err
+	}
+	ix.logf("catalog graph: revision %d of source revision %d kept, %d entries, %d changed", rev.Revision, src, len(rev.Entries), len(changed))
+	if ix.SayCatalogRevision != nil {
+		if err := ix.SayCatalogRevision(ctx, meshcatalog.CatalogRevisionEvent{V: CatalogEntryLayout, Revision: rev.Revision, Kind: rev.Kind,
+			Source: src, At: &at, Changed: changed, Entries: int64(len(rev.Entries))}); err != nil {
+			ix.logf("catalog graph: revision %d is not said: %v", rev.Revision, err)
+		}
+	}
+	return nil
+}
diff --git a/modules/mesh-delivery-indexer/internal/index/graph.go b/modules/mesh-delivery-indexer/internal/index/graph.go
index 199f9f7d..2d37097f 100644
--- a/modules/mesh-delivery-indexer/internal/index/graph.go
+++ b/modules/mesh-delivery-indexer/internal/index/graph.go
@@ -81,22 +81,7 @@ func (ix *Indexer) writeGraph(ctx context.Context, edges map[string]graphEdges)
 			GraphMost, len(names), names[GraphMost], len(names)-GraphMost-1)
 		names = names[:GraphMost]
 	}
-	providers := func(provision string) []catalogue.Manifest {
-		var out []catalogue.Manifest
-		for _, name := range slices.Sorted(maps.Keys(edges)) {
-			if slices.Contains(edges[name].manifest.Offers(), provision) {
-				out = append(out, edges[name].manifest)
-			}
-		}
-		return out
-	}
-	// The verb edges on a cycle are left out over the whole graph (ADR 0614 §3), every module it knows, so a module past
-	// GraphMost still closes the cycle it lies on.
-	whole := graph.Graph{}
-	for name, e := range edges {
-		whole[name] = graphNode(e, providers)
-	}
-	whole.LeaveOut()
+	whole := wholeGraph(edges)
 	for _, name := range names {
 		key, err := graph.Key(name)
 		if err != nil {
@@ -141,3 +126,23 @@ func (ix *Indexer) writeGraph(ctx context.Context, edges map[string]graphEdges)
 	}
 	return nil
 }
+
+// wholeGraph is the module graph of every module of edges, the verb edges on a cycle left out over the whole graph
+// (ADR 0614 §3), so a module past GraphMost still closes the cycle it lies on.
+func wholeGraph(edges map[string]graphEdges) graph.Graph {
+	providers := func(provision string) []catalogue.Manifest {
+		var out []catalogue.Manifest
+		for _, name := range slices.Sorted(maps.Keys(edges)) {
+			if slices.Contains(edges[name].manifest.Offers(), provision) {
+				out = append(out, edges[name].manifest)
+			}
+		}
+		return out
+	}
+	whole := graph.Graph{}
+	for name, e := range edges {
+		whole[name] = graphNode(e, providers)
+	}
+	whole.LeaveOut()
+	return whole
+}
diff --git a/modules/mesh-delivery-indexer/internal/index/pending.go b/modules/mesh-delivery-indexer/internal/index/pending.go
index 242886a9..4756fd1e 100644
--- a/modules/mesh-delivery-indexer/internal/index/pending.go
+++ b/modules/mesh-delivery-indexer/internal/index/pending.go
@@ -886,7 +886,7 @@ func (ix *Indexer) dry() *dryRun {
 		Requirements: nil, Findings: nil, SeatDefinitions: nil, ReadFile: ix.ReadFile, SaySeatDefinition: nil,
 		Holds: nil, Counted: nil, AskEngines: nil, HoldBounds: nil, OwnBuildState: nil, underSeats: true,
 		// A dry run keeps no catalog graph revision (catalog_revisions.go): its revision is the take-in's to keep.
-		Revisions: nil}
+		Revisions: nil, SayCatalogRevision: nil}
 	x.Logf = func(format string, args ...any) { ix.logf("take-in, computed and not written: "+format, args...) }
 	x.Store, d.candidates = over(ix.Store)
 	x.Modules, d.modules = over(ix.Modules)
diff --git a/modules/mesh-delivery-indexer/internal/index/pending_test.go b/modules/mesh-delivery-indexer/internal/index/pending_test.go
index efa3a483..6a82b105 100644
--- a/modules/mesh-delivery-indexer/internal/index/pending_test.go
+++ b/modules/mesh-delivery-indexer/internal/index/pending_test.go
@@ -970,7 +970,7 @@ func TestTakeIn(t *testing.T) { // 1585/T3-T13 (ADR 0633)
 		for _, f := range []string{"Store", "Modules", "Manifests", "Predefined", "ConfigCandidates", "Taken", "Verdicts", "OldSections", "Unjudged",
 			"JudgeID", "SayRefused", "SayAccepted", "Packages", "Graph", "Files", "GoSum", "GoMod", "Now", "Builds", "Named", "Trunk",
 			"Read", "Contains", "Logf", "ReadOpen", "OwnBuild", "Message", "Pending", "SayTakeIn",
-			"Requirements", "Findings", "SeatDefinitions", "ReadFile", "SaySeatDefinition", "Holds", "Counted", "AskEngines", "HoldBounds", "OpenTries", "TryRecovery", "OwnBuildState", "Revisions"} {
+			"Requirements", "Findings", "SeatDefinitions", "ReadFile", "SaySeatDefinition", "Holds", "Counted", "AskEngines", "HoldBounds", "OpenTries", "TryRecovery", "OwnBuildState", "Revisions", "SayCatalogRevision"} {
 			named[f] = true
 		}
 		ty := reflect.TypeOf(Indexer{})
diff --git a/modules/mesh-delivery-indexer/internal/index/toolchains.go b/modules/mesh-delivery-indexer/internal/index/toolchains.go
index 2ffb0617..0f8b0f29 100644
--- a/modules/mesh-delivery-indexer/internal/index/toolchains.go
+++ b/modules/mesh-delivery-indexer/internal/index/toolchains.go
@@ -372,7 +372,10 @@ func (ix *Indexer) recomputeLocked(ctx context.Context, overlay map[string]meshc
 	if err := ix.writeOverlay(ctx, overlay, finals, w); err != nil {
 		return err
 	}
-	return ix.writeGraph(ctx, edges)
+	if err := ix.writeGraph(ctx, edges); err != nil {
+		return err
+	}
+	return ix.keepTrunkRevision(ctx, edges, wholeGraph(edges))
 }
 
 // writeOverlay writes the records of a merge, each once and only if it differs from what the bucket holds; finals has
diff --git a/modules/mesh-delivery-indexer/internal/index/toolchains_test.go b/modules/mesh-delivery-indexer/internal/index/toolchains_test.go
index 73f7a37d..5b9821dc 100644
--- a/modules/mesh-delivery-indexer/internal/index/toolchains_test.go
+++ b/modules/mesh-delivery-indexer/internal/index/toolchains_test.go
@@ -332,16 +332,34 @@ func TestBasesAreComputedFirstAndNoFingerprintTakesTheBuilder(t *testing.T) { //
 	if _, _, err := ReadRevision(context.Background(), kept, "trunk.2"); err == nil || !strings.Contains(err.Error(), next.Entries[0].Module) {
 		t.Errorf("trunk.2 with a lost entry read without error naming it: %v", err)
 	}
+	// W4.3: a recompute keeps a trunk revision of the module graph and says catalog-revision; one that moves no entry keeps
+	// none; a module leaving makes the next revision, naming it changed.
+	ix.Revisions = newMemObjects(0)
+	var revisions []meshcatalog.CatalogRevisionEvent
+	ix.SayCatalogRevision = func(_ context.Context, e meshcatalog.CatalogRevisionEvent) error {
+		revisions = append(revisions, e)
+		return nil
+	}
+	if err := ix.Recompute(context.Background()); err != nil || len(revisions) != 1 || revisions[0].Revision != 1 || revisions[0].Kind != "trunk" ||
+		revisions[0].Entries != int64(len(mods.vals)) || len(revisions[0].Changed) != len(mods.vals) {
+		t.Fatalf("the first recompute said %+v (%v), want trunk revision 1 with every module", revisions, err)
+	}
 	graph := ix.Graph.(*memStore)
 	written := graph.writes
-	if err := ix.Recompute(context.Background()); err != nil || graph.writes != written {
-		t.Errorf("a recompute that moves nothing wrote the graph %d times (%v)", graph.writes-written, err)
+	if err := ix.Recompute(context.Background()); err != nil || graph.writes != written || len(revisions) != 1 {
+		t.Errorf("a recompute that moves nothing wrote the graph %d times and said %d revisions (%v)", graph.writes-written, len(revisions), err)
 	}
 	// A module the modules state no longer holds (a merge dropped it, issue 1900) leaves the graph at the next recompute.
 	delete(mods.vals, "other")
 	if err := ix.Recompute(context.Background()); err != nil {
 		t.Fatal(err)
 	}
+	if len(revisions) != 2 || revisions[1].Revision != 2 || !reflect.DeepEqual(revisions[1].Changed, []string{"other"}) {
+		t.Errorf("after other left, said %+v, want revision 2 naming other changed", revisions)
+	}
+	if _, kept, err := ReadRevision(context.Background(), ix.Revisions, "trunk.2"); err != nil || len(kept) != len(mods.vals) {
+		t.Errorf("trunk.2 holds %d entries (%v), want %d", len(kept), err, len(mods.vals))
+	}
 	if _, held := graph.vals["other"]; held {
 		t.Error("graph.other is still held after its module went")
 	}