diff --git a/contracts/go/clients/meshwantsclient/wants_test.go b/contracts/go/clients/meshwantsclient/wants_test.go
index 490fa692..a621583d 100644
--- a/contracts/go/clients/meshwantsclient/wants_test.go
+++ b/contracts/go/clients/meshwantsclient/wants_test.go
@@ -42,6 +42,7 @@ func TestWantsAreWhatTheEarlierCodecWrote(t *testing.T) {
 			"put":       {Want{Fp: a, Self: true, Put: true, Hold: true, Yes: d, Release: "r1"}, `{"v":1,"fp":"` + a + `","put":true,"hold":true,"yes":"` + d + `","release":"r1","self":true}`},
 			"removed":   {Want{Removed: true, Words: "gone"}, `{"v":1,"removed":true,"words":"gone"}`},
 			"released":  {Want{Fp: a, Composed: c, Version: "0.1.15", Parts: map[string]string{"mesh-sdk:go": d}}, `{"v":1,"fp":"` + a + `","composed":"` + c + `","version":"0.1.15","parts":{"mesh-sdk:go":"` + d + `"}}`},
+			"kept":      {Want{Fp: a, Composed: c, Parts: map[string]string{"x:image": d}, KeptOn: "n1"}, `{"v":1,"fp":"` + a + `","composed":"` + c + `","parts":{"x:image":"` + d + `"},"kept-on":"n1"}`},
 		} {
 			t.Run(name, func(t *testing.T) {
 				raw, err := EncodeWant(row.w)
diff --git a/contracts/go/seats/meshwants/contract.go b/contracts/go/seats/meshwants/contract.go
index 7e958b08..23b263fc 100644
--- a/contracts/go/seats/meshwants/contract.go
+++ b/contracts/go/seats/meshwants/contract.go
@@ -865,7 +865,7 @@ type VersionDeliveredEvent struct {
 	Away []string `json:"away,omitempty"`
 	// the module
 	Module string `json:"module"`
-	// the digest of each of its parts, by artifact reference
+	// the digest of each of its parts, by `<module>:<artifact>`
 	Parts map[string]string `json:"parts"`
 	V     int64             `json:"v"`
 	// MAJOR.MINOR.PATCH
@@ -895,8 +895,10 @@ type WantsByWantNodeModuleValue struct {
 	Composed string `json:"composed,omitempty"`
 	Fp       string `json:"fp,omitempty"`
 	Hold     bool   `json:"hold,omitempty"`
-	Newest   string `json:"newest,omitempty"`
-	// the digest of each of the module's parts, by artifact reference; the node-engine fetches and checks each part by it (design 47 G section 379)
+	// for a kept build, the build node that keeps it, from the builder's build.ended; the node-engine fetches the build through that node's seat verb kept-artifact, and a want with none from the store (design 47 G section 526)
+	KeptOn string `json:"kept-on,omitempty"`
+	Newest string `json:"newest,omitempty"`
+	// the digest of each of the module's parts, by `<module>:<artifact>`; the node-engine fetches and checks each part by it (design 47 G section 379)
 	Parts   map[string]string `json:"parts,omitempty"`
 	Put     bool              `json:"put,omitempty"`
 	Release string            `json:"release,omitempty"`
diff --git a/contracts/go/seats/meshwants/contract_test.go b/contracts/go/seats/meshwants/contract_test.go
index b21c64c9..32f26b23 100644
--- a/contracts/go/seats/meshwants/contract_test.go
+++ b/contracts/go/seats/meshwants/contract_test.go
@@ -65,6 +65,12 @@ func TestFixtures(t *testing.T) {
 				err := json.Unmarshal(b, &v)
 				return v, err
 			}, subjectIs: nil},
+		{name: "a want for a kept build, naming the node that keeps it", subject: "", given: "{\"fp\":\"ab12\",\"kept-on\":\"n1\",\"parts\":{\"x:image\":\"sha256:0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef\"},\"v\":1,\"version\":\"0.1.15\"}", wire: "{\"fp\":\"ab12\",\"kept-on\":\"n1\",\"parts\":{\"x:image\":\"sha256:0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef\"},\"v\":1,\"version\":\"0.1.15\"}",
+			decode: func(b []byte) (any, error) {
+				var v WantsByWantNodeModuleValue
+				err := json.Unmarshal(b, &v)
+				return v, err
+			}, subjectIs: nil},
 		{name: "a node's own want", subject: "", given: "{\"composed\":\"sha256:aa\",\"self\":true,\"v\":1}", wire: "{\"composed\":\"sha256:aa\",\"self\":true,\"v\":1}",
 			decode: func(b []byte) (any, error) {
 				var v WantsByWantNodeNodeValue
diff --git a/contracts/seats/mesh-wants/fixtures/states.json b/contracts/seats/mesh-wants/fixtures/states.json
index 818850d5..85e5d74c 100644
--- a/contracts/seats/mesh-wants/fixtures/states.json
+++ b/contracts/seats/mesh-wants/fixtures/states.json
@@ -8,6 +8,19 @@
       "rule": 3
     }
   },
+  {
+    "name": "a want for a kept build, naming the node that keeps it",
+    "of": "state:wants/want.<node>.<module>",
+    "given": {
+      "v": 1,
+      "fp": "ab12",
+      "version": "0.1.15",
+      "parts": {
+        "x:image": "sha256:0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
+      },
+      "kept-on": "n1"
+    }
+  },
   {
     "name": "a node's own want",
     "of": "state:wants/want.<node>.node",
diff --git a/contracts/seats/mesh-wants/seat.json b/contracts/seats/mesh-wants/seat.json
index ca64e17c..f149808c 100644
--- a/contracts/seats/mesh-wants/seat.json
+++ b/contracts/seats/mesh-wants/seat.json
@@ -414,7 +414,7 @@
             "additionalProperties": {
               "type": "string"
             },
-            "description": "the digest of each of its parts, by artifact reference"
+            "description": "the digest of each of its parts, by `<module>:<artifact>`"
           },
           "away": {
             "type": "array",
@@ -541,7 +541,11 @@
                 "additionalProperties": {
                   "type": "string"
                 },
-                "description": "the digest of each of the module's parts, by artifact reference; the node-engine fetches and checks each part by it (design 47 G section 379)"
+                "description": "the digest of each of the module's parts, by `<module>:<artifact>`; the node-engine fetches and checks each part by it (design 47 G section 379)"
+              },
+              "kept-on": {
+                "type": "string",
+                "description": "for a kept build, the build node that keeps it, from the builder's build.ended; the node-engine fetches the build through that node's seat verb kept-artifact, and a want with none from the store (design 47 G section 526)"
               }
             }
           },
diff --git a/contracts/ts/seats/meshwants/index.d.ts b/contracts/ts/seats/meshwants/index.d.ts
index 134842cd..ee5a58f3 100644
--- a/contracts/ts/seats/meshwants/index.d.ts
+++ b/contracts/ts/seats/meshwants/index.d.ts
@@ -491,7 +491,7 @@ export interface VersionDeliveredEvent {
   "away"?: string[];
   /** the module */
   "module": string;
-  /** the digest of each of its parts, by artifact reference */
+  /** the digest of each of its parts, by `<module>:<artifact>` */
   "parts": Record<string, string>;
   "v": number;
   /** MAJOR.MINOR.PATCH */
@@ -513,8 +513,10 @@ export interface WantsByWantNodeModuleValue {
   "composed"?: string;
   "fp"?: string;
   "hold"?: boolean;
+  /** for a kept build, the build node that keeps it, from the builder's build.ended; the node-engine fetches the build through that node's seat verb kept-artifact, and a want with none from the store (design 47 G section 526) */
+  "kept-on"?: string;
   "newest"?: string;
-  /** the digest of each of the module's parts, by artifact reference; the node-engine fetches and checks each part by it (design 47 G section 379) */
+  /** the digest of each of the module's parts, by `<module>:<artifact>`; the node-engine fetches and checks each part by it (design 47 G section 379) */
   "parts"?: Record<string, string>;
   "put"?: boolean;
   "release"?: string;
diff --git a/modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/buildended.go b/modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/buildended.go
new file mode 100644
index 00000000..0dcbb895
--- /dev/null
+++ b/modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/buildended.go
@@ -0,0 +1,124 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"sync"
+
+	"git.novox.be/novox/mesh-delivery/contracts/go/seats/meshcatalog"
+	"git.novox.be/novox/mesh-sdk/go/process"
+	"github.com/nats-io/nats.go/jetstream"
+
+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-builder/builds"
+	"mesh-delivery-assigner/internal/assign"
+)
+
+// What a want names of a build is heard, never read from the builder's state (design 47 G §379, §526, A-94, A-96; ADR 0596 §2): the
+// builder's event `build.ended` (a done build's parts by digest, its keeping node and its branch) and the catalog's
+// `version-released` (a released version and each part's digest, with the source revision it was built from), each kept as heard.
+
+// buildEndedSubjects is the builder's event build.ended on its own stream, as the manifest's consumes names it
+// (`mesh-delivery-builder.build.ended`), each module and fingerprint after it.
+var buildEndedSubjects = process.ModuleStreamSubject(builds.BuilderModule, builds.BuildEndedEvent+".>")
+
+// builtEnds are the done builds' ends heard, by module and fingerprint (hearBuildEnded).
+type builtEnds struct {
+	mu   sync.Mutex
+	ends map[string]builds.BuildEnded
+}
+
+func (b *builtEnds) key(module, fp string) string { return module + "@" + fp }
+
+// put takes one build.ended in.
+func (b *builtEnds) put(data []byte) error {
+	var e builds.BuildEnded
+	if err := json.Unmarshal(data, &e); err != nil {
+		return fmt.Errorf("a build.ended that is no end: %w", err)
+	}
+	if e.Module == "" || e.Fingerprint == "" {
+		return fmt.Errorf("a build's end naming no module or fingerprint: %s", data)
+	}
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	if b.ends == nil {
+		b.ends = map[string]builds.BuildEnded{}
+	}
+	b.ends[b.key(e.Module, e.Fingerprint)] = e
+	return nil
+}
+
+// partsOf is the parts of module's build at fp as its end names them (each artifact's digest by `<module>:<artifact>`), with the
+// node that keeps it, for a kept build or a build of another watched branch; false for a build of the trunk not kept, whose
+// parts the version's release says (releasedVersions).
+func (b *builtEnds) partsOf(module, fp string) (assign.KeptBuild, bool) {
+	b.mu.Lock()
+	e, ok := b.ends[b.key(module, fp)]
+	b.mu.Unlock()
+	if !ok || (e.KeptOn == "" && e.Branch == "") {
+		return assign.KeptBuild{}, false
+	}
+	parts := map[string]string{}
+	for name, digest := range e.Made {
+		parts[module+":"+name] = digest
+	}
+	return assign.KeptBuild{Parts: parts, KeptOn: e.KeptOn}, true
+}
+
+// releasedVersions are the catalog's version-released heard, by module and source revision.
+type releasedVersions struct {
+	mu   sync.Mutex
+	seen map[string]assign.KeptBuild
+}
+
+func (r *releasedVersions) key(module string, source int64) string {
+	return fmt.Sprintf("%s@%d", module, source)
+}
+
+// put takes one version-released in.
+func (r *releasedVersions) put(data []byte) error {
+	var e meshcatalog.VersionReleasedEvent
+	if err := json.Unmarshal(data, &e); err != nil {
+		return fmt.Errorf("a version-released that is none: %w", err)
+	}
+	if e.Module == "" || e.Version == "" {
+		return fmt.Errorf("a version-released naming no module or version: %s", data)
+	}
+	parts := map[string]string{}
+	for _, a := range e.Artifacts {
+		parts[e.Module+":"+a.Artifact] = a.Digest
+	}
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	if r.seen == nil {
+		r.seen = map[string]assign.KeptBuild{}
+	}
+	r.seen[r.key(e.Module, e.Source)] = assign.KeptBuild{Version: e.Version, Parts: parts}
+	return nil
+}
+
+// of is the version of module released from the source revision, with its parts' digests; false before it is heard.
+func (r *releasedVersions) of(module string, source int64) (assign.KeptBuild, bool) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	k, ok := r.seen[r.key(module, source)]
+	return k, ok
+}
+
+// hearBuildsAndReleases registers the hub's takers of build.ended and version-released, each waking the pass; before the hub starts.
+func hearBuildsAndReleases(hub *process.EventHub, ends *builtEnds, released *releasedVersions, wake func(), logf func(string, ...any)) error {
+	taker := func(put func([]byte) error) func(jetstream.Msg) {
+		return func(m jetstream.Msg) {
+			if err := put(m.Data()); err != nil {
+				logf("%s is not kept: %v", m.Subject(), err)
+			}
+			if err := m.Ack(); err != nil {
+				logf("acknowledging %s: %v", m.Subject(), err)
+			}
+			wake()
+		}
+	}
+	if err := hub.Handle(buildEndedSubjects, taker(ends.put)); err != nil {
+		return err
+	}
+	return hub.Handle(meshcatalog.SubjectVersionReleased, taker(released.put))
+}
diff --git a/modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/buildended_test.go b/modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/buildended_test.go
new file mode 100644
index 00000000..ffe0c50f
--- /dev/null
+++ b/modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/buildended_test.go
@@ -0,0 +1,88 @@
+package main
+
+import (
+	"encoding/json"
+	"reflect"
+	"testing"
+
+	"git.novox.be/novox/mesh-delivery/contracts/go/seats/meshcatalog"
+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-builder/builds"
+	"mesh-delivery-assigner/internal/assign"
+)
+
+// Design 47 G §379, §526, A-96: a build.ended heard names a kept build's or another branch's parts by digest (`<module>:<artifact>`) and its
+// keeping node; a build of the trunk not kept names none, its parts being the release's.
+func TestABuildEndedHeardNamesAKeptBuildsPartsAndItsNode(t *testing.T) {
+	put := func(b *builtEnds, e builds.BuildEnded) {
+		raw, _ := json.Marshal(e)
+		if err := b.put(raw); err != nil {
+			t.Fatal(err)
+		}
+	}
+	made := map[string]string{"program": "sha256:1"}
+	var b builtEnds
+	put(&b, builds.BuildEnded{Module: "node-engine", Fingerprint: "a", Made: made})
+	if _, ok := b.partsOf("node-engine", "a"); ok {
+		t.Error("a trunk build not kept names parts")
+	}
+	put(&b, builds.BuildEnded{Module: "node-engine", Fingerprint: "b", Made: made, KeptOn: "ace"})
+	if k, ok := b.partsOf("node-engine", "b"); !ok || k.KeptOn != "ace" || !reflect.DeepEqual(k.Parts, map[string]string{"node-engine:program": "sha256:1"}) {
+		t.Errorf("kept build = %+v, %v", k, ok)
+	}
+	put(&b, builds.BuildEnded{Module: "node-engine", Fingerprint: "c", Made: made, Branch: "cand"})
+	if k, ok := b.partsOf("node-engine", "c"); !ok || k.KeptOn != "" || len(k.Parts) != 1 {
+		t.Errorf("branch build = %+v, %v", k, ok)
+	}
+	if err := b.put([]byte(`{"module":"x"}`)); err == nil {
+		t.Error("an end naming no fingerprint is kept")
+	}
+}
+
+// Design 47 G §379, A-96: a version-released heard names the version and the parts' digests of the module's source revision.
+func TestAVersionReleasedHeardNamesItsVersionAndPartsBySource(t *testing.T) {
+	var r releasedVersions
+	raw, _ := json.Marshal(meshcatalog.VersionReleasedEvent{Module: "mail", Source: 7, Version: "1.2.3", Artifacts: []meshcatalog.VersionArtifact{{Artifact: "image", Digest: "sha256:9"}}})
+	if err := r.put(raw); err != nil {
+		t.Fatal(err)
+	}
+	want := assign.KeptBuild{Version: "1.2.3", Parts: map[string]string{"mail:image": "sha256:9"}}
+	if k, ok := r.of("mail", 7); !ok || !reflect.DeepEqual(k, want) {
+		t.Errorf("released = %+v, %v", k, ok)
+	}
+	if _, ok := r.of("mail", 8); ok {
+		t.Error("another source revision names a version")
+	}
+}
+
+// Design 47 G §379, A-96: the trunk's entry takes its version and parts from the version-released of the kept assignment graph
+// revision's source; a kept build from its end; no revision kept, or another fingerprint, names none.
+func TestATrunkEntryTakesItsVersionFromTheReleaseOfTheKeptRevisionsSource(t *testing.T) {
+	w := newWorld()
+	raw, _ := json.Marshal(meshcatalog.VersionReleasedEvent{Module: "mail", Source: 7, Version: "1.2.3", Artifacts: []meshcatalog.VersionArtifact{{Artifact: "image", Digest: "sha256:9"}}})
+	if err := w.released.put(raw); err != nil {
+		t.Fatal(err)
+	}
+	endRaw, _ := json.Marshal(builds.BuildEnded{Module: "mail", Fingerprint: "k", Made: map[string]string{"image": "sha256:2"}, KeptOn: "g14"})
+	if err := w.ends.put(endRaw); err != nil {
+		t.Fatal(err)
+	}
+	p := &passer{w: w, graph: &graphKeeper{ok: true, source: 7}}
+	named := p.namedBuild("mail", "t")
+	if k, ok := named("t"); !ok || k.Version != "1.2.3" || k.Parts["mail:image"] != "sha256:9" || k.KeptOn != "" {
+		t.Errorf("trunk entry = %+v, %v", k, ok)
+	}
+	if k, ok := named("k"); !ok || k.KeptOn != "g14" || k.Version != "" {
+		t.Errorf("kept build = %+v, %v", k, ok)
+	}
+	if _, ok := named("other"); ok {
+		t.Error("another fingerprint names a release")
+	}
+	p.graph.source = 8
+	if _, ok := named("t"); ok {
+		t.Error("a source with no release names a version")
+	}
+	p.graph.ok = false
+	if _, ok := p.namedBuild("mail", "t")("t"); ok {
+		t.Error("no revision kept names a release")
+	}
+}
diff --git a/modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/graphkept.go b/modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/graphkept.go
index 941d3bc2..9ea4bbec 100644
--- a/modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/graphkept.go
+++ b/modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/graphkept.go
@@ -14,6 +14,7 @@ import (
 	"git.novox.be/novox/mesh-delivery/contracts/go/seats/meshwants"
 	"git.novox.be/novox/mesh-sdk/go/keys"
 
+	"mesh-delivery-assigner/internal/assign"
 	"mesh-delivery-assigner/internal/assigngraph"
 )
 
@@ -118,3 +119,18 @@ func (p *passer) sayWanted(node, module, fp string, removed bool) {
 		p.logf("wanted of %s on %s is not said: %v", module, node, err)
 	}
 }
+
+// namedBuild answers what a want of module at fp names of its build (design 47 G §379, §526, A-96): a kept build's or another watched
+// branch's parts and keeping node from the builder's `build.ended`; for the trunk's entry (fp is the module's, trunkFP), the released
+// version and the parts of the `version-released` whose source is the one the kept assignment graph revision was computed from (A-67).
+func (p *passer) namedBuild(module, trunkFP string) func(fp string) (assign.KeptBuild, bool) {
+	return func(fp string) (assign.KeptBuild, bool) {
+		if k, ok := p.w.ends.partsOf(module, fp); ok {
+			return k, true
+		}
+		if fp != trunkFP || p.graph == nil || !p.graph.ok {
+			return assign.KeptBuild{}, false
+		}
+		return p.w.released.of(module, p.graph.source)
+	}
+}
diff --git a/modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/main.go b/modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/main.go
index ca6e6d0e..fc0366c0 100644
--- a/modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/main.go
+++ b/modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/main.go
@@ -576,6 +576,9 @@ func follow(ctx context.Context, js jetstream.JetStream, nc process.Subscriber,
 				logger.Printf("a pipeline's end or a registration is not heard, so the wants keep the trunk-only form until the assigner starts again: %v", err)
 			}
 		}
+		if err := hearBuildsAndReleases(hub, &w.ends, &w.released, wake, logger.Printf); err != nil {
+			logger.Printf("a build's end or a version's release is not heard, so no want names a build's parts, its keeping node or its version until the assigner starts again: %v", err)
+		}
 		hearReadsChanged(ctx, js, hub, reads, findings, gate.EventsLive, logger.Printf)
 		hearRunning(ctx, js, w, wake, findings, logger.Printf)
 	}
diff --git a/modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/pass.go b/modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/pass.go
index 2e6026d2..49a73c03 100644
--- a/modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/pass.go
+++ b/modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/pass.go
@@ -325,6 +325,7 @@ func (p *passer) wants(ctx context.Context) {
 					held, _ := mwc.HeldKey(name, fp)
 					grant, _ := grantsstate.PartGrantKey(name, fp)
 					hold, _ := asks.HoldAskKey(name, fp)
+					m.KeptBuilds = p.namedBuild(name, m.FP)
 					m.Released = p.answeredWith(hold, "release")
 					m.Kept = p.answeredWith(hold, "keep")
 					m.Built, m.Held, m.Granted = p.w.built(name, fp), p.w.has(buckets.Wants, held) && !m.Released, p.w.has(grants, grant)
diff --git a/modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/world.go b/modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/world.go
index 876e04e0..bb0c9fdb 100644
--- a/modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/world.go
+++ b/modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/world.go
@@ -41,8 +41,10 @@ type world struct {
 	changes map[string]uint64
 	// meta is, by bucket and key, the revision and the time of the value held now, where the watch said them (putEntry).
 	meta map[string]entryMeta
-	// trunkBuilt is, by module, its newest done trunk build in the builder's log (putBuilt).
-	trunkBuilt map[string]builds.BuildLogEntry
+	// ends are the done builds' ends the builder says (build.ended), by module and fingerprint (buildlog.go).
+	ends builtEnds
+	// released are the catalog's version-released heard, by module and source revision (buildended.go).
+	released releasedVersions
 	// assignments is the seat's state assignments assembled node by node from its keys in either form (mesh-sdk
 	// mmac.Keys; research 072 row 37): the one reader of its keys in the assigner.
 	assignmentKeys *mmac.Keys
@@ -74,7 +76,7 @@ type parsed struct {
 
 func newWorld() *world {
 	return &world{values: map[string]map[string][]byte{}, manifests: map[string]parsed{}, healthy: map[string][]string{}, changes: map[string]uint64{},
-		meta: map[string]entryMeta{}, trunkBuilt: map[string]builds.BuildLogEntry{}, assignmentKeys: mmac.NewKeys(),
+		meta: map[string]entryMeta{}, assignmentKeys: mmac.NewKeys(),
 		sourceGroups: map[uint64]string{}, running: map[string]nodeengine.Running{},
 		modules: map[string]map[string]meshcatalog.ModulesByModuleValue{}, graphs: map[string]map[string]graph.Node{}}
 }
diff --git a/modules/mesh-delivery-assigner/internal/assign/wants.go b/modules/mesh-delivery-assigner/internal/assign/wants.go
index 7d4774fe..1d278f17 100644
--- a/modules/mesh-delivery-assigner/internal/assign/wants.go
+++ b/modules/mesh-delivery-assigner/internal/assign/wants.go
@@ -95,11 +95,41 @@ type Module struct {
 	// source of a want's Self: every want the rules write or keep is derived from it (selfDerived), so a want written Self while
 	// the node was placed does not outlive the assignments (issue 1126). Nil: no node does.
 	Self func(node string) bool
+	// KeptBuilds answers what a want at a fingerprint names of its build: its parts and its keeping node as the builder's `build.ended`
+	// names them, or the released version and parts of the catalog's `version-released` (design 47 G §379, §526, A-96), for a node that states the capability WantParts. Nil: none is read.
+	KeptBuilds func(fp string) (KeptBuild, bool)
 	// MachineHeld says whether the node's own network condition is open, which holds the machine as a whole: no want moves to it
 	// until that clears (design 47 G §706 *M's own network*). Nil: none is held.
 	MachineHeld func(node string) bool
 }
 
+// WantParts is the capability a node-engine of G states (ADR 0614 §4, design 47 G §525): it reads a want's `parts` and `kept-on`.
+const WantParts = "want-parts"
+
+// KeptBuild is what a want names of a build: the digest of each of its parts by `<module>:<artifact>`, and, as the builder's
+// `build.ended` says it, the build node that keeps a kept build; for a trunk build the released version the catalog's
+// `version-released` says (design 47 G §379, §526, A-96).
+type KeptBuild struct {
+	Parts   map[string]string
+	KeptOn  string
+	Version string
+}
+
+// withKept is w naming the kept build at its fingerprint, the parts by digest and the keeping node, only while the node's
+// engine states WantParts (design 47 G §525, §526); a want of a build that is not kept, or of a node that does not state it,
+// is w.
+func (n Nodes) withKept(m Module, node string, w mwc.Want) mwc.Want {
+	if m.KeptBuilds == nil {
+		return w
+	}
+	k, ok := m.KeptBuilds(w.Fp)
+	if !ok || !slices.Contains(n.Reads[node], WantParts) {
+		return w
+	}
+	w.Parts, w.KeptOn, w.Version = k.Parts, k.KeptOn, k.Version
+	return w
+}
+
 func (m Module) selfOn(node string) bool { return m.Self != nil && m.Self(node) }
 
 func (m Module) composition(node, fp string) (ComposedDigest, bool) {
@@ -514,7 +544,7 @@ func Wants(m Module, n Nodes, wants map[string]mwc.Want, lastHealthy map[string]
 		switch {
 		case ok:
 			d, _ := m.composition(node, target)
-			next = mwc.Want{Fp: target, Composed: d.Digest}
+			next = n.withKept(m, node, mwc.Want{Fp: target, Composed: d.Digest})
 			at := m
 			if target != m.FP {
 				// the first want at the older fingerprint the node runs: held back from F by the rule, and judged as a want at it
diff --git a/modules/mesh-delivery-assigner/internal/assign/wants_test.go b/modules/mesh-delivery-assigner/internal/assign/wants_test.go
index e3d46708..fce06ef2 100644
--- a/modules/mesh-delivery-assigner/internal/assign/wants_test.go
+++ b/modules/mesh-delivery-assigner/internal/assign/wants_test.go
@@ -1583,3 +1583,28 @@ func TestAProviderRunsHealthyByItsRunning(t *testing.T) {
 		}
 	}
 }
+
+// Design 47 G §525, §526: a want at a kept build names its parts and the node that keeps it, only for a node whose engine states
+// the capability want-parts.
+func TestAWantNamesAKeptBuildsPartsAndNodeForANodeThatReadsThem(t *testing.T) {
+	kept := KeptBuild{Parts: map[string]string{"mail:image": "sha256:1"}, KeptOn: "g14", Version: "1.2.3"}
+	for name, row := range map[string]struct {
+		reads  []string
+		kept   func(string) (KeptBuild, bool)
+		wanted bool
+	}{
+		"states it":       {[]string{WantParts}, func(fp string) (KeptBuild, bool) { return kept, fp == fNew }, true},
+		"does not state":  {[]string{"form:oci"}, func(fp string) (KeptBuild, bool) { return kept, fp == fNew }, false},
+		"build not kept":  {[]string{WantParts}, func(string) (KeptBuild, bool) { return KeptBuild{}, false }, false},
+		"no kept builds":  {[]string{WantParts}, nil, false},
+		"another fingerp": {[]string{WantParts}, func(fp string) (KeptBuild, bool) { return kept, fp == fOld }, false},
+	} {
+		m, n := ready()
+		n.Reads = map[string][]string{"ace": row.reads, "g14": row.reads}
+		m.KeptBuilds = row.kept
+		w := Wants(m, n, wantedOld(), nil).Wants["ace"]
+		if w.Fp != fNew || (w.KeptOn == "g14") != row.wanted || (w.Version == "1.2.3") != row.wanted || (len(w.Parts) == 1) != row.wanted {
+			t.Errorf("%s: ace's want = %+v", name, w)
+		}
+	}
+}
diff --git a/modules/mesh-delivery-assigner/manifest_test.go b/modules/mesh-delivery-assigner/manifest_test.go
index d28cbc9c..a536bdf1 100644
--- a/modules/mesh-delivery-assigner/manifest_test.go
+++ b/modules/mesh-delivery-assigner/manifest_test.go
@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"git.novox.be/novox/mesh-contracts/go/seats/meshmoduleassigner"
 	"git.novox.be/novox/mesh-delivery/contracts/go/seats/meshwants"
+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-builder/builds"
 	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-teller/tellerevents"
 	"os"
 	"reflect"
@@ -129,7 +130,7 @@ func TestManifest(t *testing.T) {
 	}
 	// ADR 0618 §4: and it hears each node's engine say its reads changed; ADR 0636 §4 (issue 1966): and the seat list's two events;
 	// issue 1966 note 151: and the teller's ask-ended, its subject the one the assigner hears.
-	if !slices.Equal(m.Consumes, []string{"mesh-conditions.findings-asked", "mesh-conditions.condition-raised", "mesh-conditions.condition-changed", "mesh-conditions.condition-cleared", "mesh-catalog.catalog-revision", "mesh-catalog.registration-changed", "mesh-catalog.seat-definition-changed", "mesh-catalog.seat-definition-removed", buckets.TellerModule + "." + tellerevents.AskEnded, "mesh-pipeline-runner.pipeline-ended", "mesh-pipeline-runner.group-ended", "node-engine.manifest-reads-changed", "node-engine.running"}) {
+	if !slices.Equal(m.Consumes, []string{"mesh-conditions.findings-asked", "mesh-conditions.condition-raised", "mesh-conditions.condition-changed", "mesh-conditions.condition-cleared", "mesh-catalog.catalog-revision", "mesh-catalog.registration-changed", "mesh-catalog.version-released", "mesh-catalog.seat-definition-changed", "mesh-catalog.seat-definition-removed", builds.BuilderModule + "." + builds.BuildEndedEvent, buckets.TellerModule + "." + tellerevents.AskEnded, "mesh-pipeline-runner.pipeline-ended", "mesh-pipeline-runner.group-ended", "node-engine.manifest-reads-changed", "node-engine.running"}) {
 		t.Errorf("consumes = %v, want the catalog half's revisions (design 47 G §195), the teller's ask-ended, the engines' reads changed and what they run", m.Consumes)
 	}
 	if want := []string{"mesh-delivery-indexer.manifests", "mesh-delivery-indexer.modules",
diff --git a/modules/mesh-delivery-assigner/module.json b/modules/mesh-delivery-assigner/module.json
index 869eb605..aaf2d344 100644
--- a/modules/mesh-delivery-assigner/module.json
+++ b/modules/mesh-delivery-assigner/module.json
@@ -50,8 +50,10 @@
     "mesh-conditions.condition-cleared",
     "mesh-catalog.catalog-revision",
     "mesh-catalog.registration-changed",
+    "mesh-catalog.version-released",
     "mesh-catalog.seat-definition-changed",
     "mesh-catalog.seat-definition-removed",
+    "mesh-delivery-builder.build.ended",
     "mesh-delivery-teller.ask-ended",
     "mesh-pipeline-runner.pipeline-ended",
     "mesh-pipeline-runner.group-ended",
diff --git a/modules/mesh-delivery-builder/builds/ended.go b/modules/mesh-delivery-builder/builds/ended.go
new file mode 100644
index 00000000..0f01a3d1
--- /dev/null
+++ b/modules/mesh-delivery-builder/builds/ended.go
@@ -0,0 +1,43 @@
+package builds
+
+import (
+	"git.novox.be/novox/mesh-sdk/go/keys"
+)
+
+// The builder says each done build's end itself, as an event on its own stream (design 47 G §379, A-96): the stream
+// BuildsStream carries `build.ended.<module>.<fingerprint>` (each part escaped), published where the log entry of the end is
+// written. A part that wants a build's parts or its keeping node hears it (the assigner consumes `mesh-delivery-builder.build.ended`).
+const (
+	// BuildsStream is the builder's stream of build ends, named by its manifest's `streams` entry.
+	BuildsStream = "mesh-delivery-builder-builds"
+	// BuildsStreamEvents is the pattern of the events that entry carries.
+	BuildsStreamEvents = BuildEndedEvent + ".**"
+)
+
+// BuildEnded is the body of the event build.ended: the module, the fingerprint, each artifact made with its digest, the build
+// node that keeps a kept build (none for one not kept) and the watched branch a build of a candidate is for (none for the trunk).
+type BuildEnded struct {
+	Module      string            `json:"module"`
+	Fingerprint string            `json:"fingerprint"`
+	Made        map[string]string `json:"made,omitempty"`
+	KeptOn      string            `json:"kept-on,omitempty"`
+	Branch      string            `json:"branch,omitempty"`
+}
+
+// BuildEndedEventName is the event's name for a module and fingerprint: `build.ended.<module>.<fingerprint>`, each escaped.
+func BuildEndedEventName(module, fp string) string {
+	return BuildEndedEvent + "." + keys.EscapeName(module) + "." + keys.EscapeName(fp)
+}
+
+// BuildEndedOf is the event of a log entry of a build's end: false for any entry but the end of a done build, which says no
+// digest of any part.
+func BuildEndedOf(e BuildLogEntry) (BuildEnded, bool) {
+	if e.Event != BuildEndedEvent || e.Outcome != BuildDone || e.Module == "" || e.FP == "" {
+		return BuildEnded{}, false
+	}
+	made := map[string]string{}
+	for _, a := range e.Made {
+		made[a.Name] = a.Digest
+	}
+	return BuildEnded{Module: e.Module, Fingerprint: e.FP, Made: made, KeptOn: e.KeptOn, Branch: e.Ref}, true
+}
diff --git a/modules/mesh-delivery-builder/builds/ended_test.go b/modules/mesh-delivery-builder/builds/ended_test.go
new file mode 100644
index 00000000..33e3f70f
--- /dev/null
+++ b/modules/mesh-delivery-builder/builds/ended_test.go
@@ -0,0 +1,32 @@
+package builds
+
+import (
+	"reflect"
+	"testing"
+)
+
+// Design 47 G §379, A-96: a done build's end is the event build.ended, its subject escaped by module and fingerprint; any other
+// entry is none.
+func TestADoneBuildsEndIsTheEventBuildEnded(t *testing.T) {
+	made := []BuiltArtifact{{Name: "program", Kind: "program", Digest: "sha256:1"}}
+	e := BuildLogEntry{Event: BuildEndedEvent, Outcome: BuildDone, Module: "node-engine", FP: "src2:a", Ref: "cand", KeptOn: "ace", Made: made}
+	got, ok := BuildEndedOf(e)
+	want := BuildEnded{Module: "node-engine", Fingerprint: "src2:a", Made: map[string]string{"program": "sha256:1"}, KeptOn: "ace", Branch: "cand"}
+	if !ok || !reflect.DeepEqual(got, want) {
+		t.Errorf("event = %+v, %v", got, ok)
+	}
+	if n := BuildEndedEventName("node-engine", "src2:a"); n != "build.ended.node-engine.src2=3aa" {
+		t.Errorf("event name = %q", n)
+	}
+	for name, mut := range map[string]func(*BuildLogEntry){
+		"started": func(e *BuildLogEntry) { e.Event = BuildStartedEvent },
+		"failed":  func(e *BuildLogEntry) { e.Outcome = BuildFailed },
+		"no fp":   func(e *BuildLogEntry) { e.FP = "" },
+	} {
+		c := e
+		mut(&c)
+		if _, ok := BuildEndedOf(c); ok {
+			t.Errorf("%s: an event", name)
+		}
+	}
+}
diff --git a/modules/mesh-delivery-builder/cmd/mesh-delivery-builder/integration_test.go b/modules/mesh-delivery-builder/cmd/mesh-delivery-builder/integration_test.go
index 7feaa294..aba095dd 100644
--- a/modules/mesh-delivery-builder/cmd/mesh-delivery-builder/integration_test.go
+++ b/modules/mesh-delivery-builder/cmd/mesh-delivery-builder/integration_test.go
@@ -314,6 +314,10 @@ func startBedWith(t *testing.T, closed bool) *bed {
 		"mesh.stream.mesh-delivery-builder.event.finding-cleared.*", "mesh.stream.mesh-delivery-builder.event.findings-stated.*"}}); err != nil {
 		t.Fatal(err)
 	}
+	// The builder's stream of build ends (design 47 G A-96), which it says build.ended into.
+	if _, err := js.CreateStream(ctx, jetstream.StreamConfig{Name: "BUILDER_BUILDS", Subjects: []string{"mesh.stream.mesh-delivery-builder.event.build.ended.>"}}); err != nil {
+		t.Fatal(err)
+	}
 	b.fake = &fakeBuildModules{js: js, ctx: ctx, calls: map[string]int{}}
 	b.fake.closed.Store(closed)
 	b.fake.serve(t, "mesh-build-go", "n1", "n2")
@@ -555,6 +559,18 @@ func TestBuilderMakesADoneKeyWithTheDigests(t *testing.T) { // 1607/AC7
 		ended[1].Manifest != digest || len(ended[1].Made) != 2 || ended[1].Node != "n1" {
 		t.Errorf("logged = %+v, want the start and the end of netcheck's build", ended)
 	}
+	// Design 47 G §379, A-96: the end is also said as the event build.ended on the builder's stream, its body the module, the
+	// fingerprint and each artifact's digest.
+	if st, err := b.js.Stream(b.ctx, "BUILDER_BUILDS"); err != nil {
+		t.Fatal(err)
+	} else if raw, err := st.GetLastMsgForSubject(b.ctx, "mesh.stream.mesh-delivery-builder.event."+builds.BuildEndedEventName("netcheck", fp)); err != nil {
+		t.Errorf("no build.ended of netcheck's build: %v", err)
+	} else {
+		var ev builds.BuildEnded
+		if err := json.Unmarshal(raw.Data, &ev); err != nil || ev.Module != "netcheck" || ev.Fingerprint != fp || len(ev.Made) != 2 {
+			t.Errorf("build.ended = %s (%v), want netcheck at its fingerprint with two artifacts' digests", raw.Data, err)
+		}
+	}
 	for tool, want := range map[string]int{"mesh-build-go.build_go_fetch": 1, "mesh-build-go.build_go_build": 1, "mesh-build-node.build_node_fetch": 1, "mesh-build-node.build_node_build": 1} {
 		if got := b.fake.count(tool); got != want {
 			t.Errorf("%s called %d times, want %d (on one node, ADR 0478 clause 4)", tool, got, want)
diff --git a/modules/mesh-delivery-builder/cmd/mesh-delivery-builder/main.go b/modules/mesh-delivery-builder/cmd/mesh-delivery-builder/main.go
index b873b4c2..d8678236 100644
--- a/modules/mesh-delivery-builder/cmd/mesh-delivery-builder/main.go
+++ b/modules/mesh-delivery-builder/cmd/mesh-delivery-builder/main.go
@@ -253,6 +253,9 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 		if err := appendLog(context.WithoutCancel(ctx), js, cred, e); err != nil {
 			logger.Printf("%v", err)
 		}
+		if err := emitBuildEnded(context.WithoutCancel(ctx), js, cred, e); err != nil {
+			logger.Printf("%v", err)
+		}
 		// A failed trunk build is the builder's finding build-failed, cleared by a later done one (DLV-B7).
 		found.buildEnded(context.WithoutCancel(ctx), e)
 	}
diff --git a/modules/mesh-delivery-builder/cmd/mesh-delivery-builder/reasks.go b/modules/mesh-delivery-builder/cmd/mesh-delivery-builder/reasks.go
index 26da5ebb..2082cf87 100644
--- a/modules/mesh-delivery-builder/cmd/mesh-delivery-builder/reasks.go
+++ b/modules/mesh-delivery-builder/cmd/mesh-delivery-builder/reasks.go
@@ -161,6 +161,34 @@ func appendLog(ctx context.Context, js jetstream.JetStream, cred process.Account
 	return nil
 }
 
+// emitBuildEnded says the builder's event build.ended of a done build, on the builder's own stream (design 47 G §379, A-96):
+// mesh.stream.<module>.event.build.ended.<module>.<fingerprint>, published where the log entry of the end is written. An
+// entry that is not a done build's end says none. The id makes a repeated end one event.
+func emitBuildEnded(ctx context.Context, js jetstream.JetStream, cred process.Account, e builds.BuildLogEntry) error {
+	body, ok := builds.BuildEndedOf(e)
+	if !ok {
+		return nil
+	}
+	data, err := json.Marshal(body)
+	if err != nil {
+		return err
+	}
+	msg := nats.NewMsg(cred.StreamSubject(builds.BuildEndedEventName(e.Module, e.FP)))
+	id := "build-ended." + e.Module + "." + e.FP + "." + e.At.Format(time.RFC3339Nano)
+	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.Data = data
+	pub, cancel := context.WithTimeout(ctx, 10*time.Second)
+	defer cancel()
+	if _, err := js.PublishMsg(pub, msg, jetstream.WithMsgID(id)); err != nil {
+		return fmt.Errorf("saying %s of %s at %s: %w", builds.BuildEndedEvent, e.Module, e.FP, err)
+	}
+	return nil
+}
+
 // versionActed answers a reasks value of builder_publish_again, builder_floor_again or builder_old_form's drop, a hand act said in the log.
 func versionActed(ctx context.Context, acts versions.Acts, kv jetstream.KeyValue, e jetstream.KeyValueEntry, r build.ReAsk, logf func(string, ...any)) {
 	var err error
diff --git a/modules/mesh-delivery-builder/manifest_test.go b/modules/mesh-delivery-builder/manifest_test.go
index 79789582..3a9a8c5b 100644
--- a/modules/mesh-delivery-builder/manifest_test.go
+++ b/modules/mesh-delivery-builder/manifest_test.go
@@ -175,9 +175,10 @@ func TestManifestDeclarations(t *testing.T) { // 1607/AC1
 	}
 	// Design 47 G §672: the toolchain waits' stream, kept 7 days within 16 MiB, and the bound's setting, 60 minutes.
 	// Design 47 G A-30, §383: and its own findings' events, which its finding writer says.
-	if len(m.Streams) != 2 || m.Streams[0].Name != "waits" || !reflect.DeepEqual(m.Streams[0].Events, []string{"wait-held.**", "wait-ended.**"}) || m.Streams[0].MaxAgeDays != 7 || m.Streams[0].MaxMiB != 16 ||
-		m.Streams[1].Name != "mesh-delivery-builder-findings" || !reflect.DeepEqual(m.Streams[1].Events, []string{"finding-written.*", "finding-cleared.*", "findings-stated.*"}) {
-		t.Errorf("streams = %+v, want waits with wait-held.** and wait-ended.**, 7 days, 16 MiB, and the findings' stream", m.Streams)
+	if len(m.Streams) != 3 || m.Streams[0].Name != "waits" || !reflect.DeepEqual(m.Streams[0].Events, []string{"wait-held.**", "wait-ended.**"}) || m.Streams[0].MaxAgeDays != 7 || m.Streams[0].MaxMiB != 16 ||
+		m.Streams[1].Name != builds.BuildsStream || !reflect.DeepEqual(m.Streams[1].Events, []string{builds.BuildsStreamEvents}) || m.Streams[1].MaxAgeDays != 7 ||
+		m.Streams[2].Name != "mesh-delivery-builder-findings" || !reflect.DeepEqual(m.Streams[2].Events, []string{"finding-written.*", "finding-cleared.*", "findings-stated.*"}) {
+		t.Errorf("streams = %+v, want waits with wait-held.** and wait-ended.**, 7 days, 16 MiB, the builds' stream (build.ended.**, 7 days) and the findings' stream", m.Streams)
 	}
 	if c, ok := m.Config["toolchain-wait-minutes"]; !ok || c.Default != float64(60) || len(m.Config) != 1 {
 		t.Errorf("config = %+v, want toolchain-wait-minutes of 60", m.Config)
diff --git a/modules/mesh-delivery-builder/module.json b/modules/mesh-delivery-builder/module.json
index ac053db9..f784dcb2 100644
--- a/modules/mesh-delivery-builder/module.json
+++ b/modules/mesh-delivery-builder/module.json
@@ -118,6 +118,7 @@
   ],
   "streams": [
     { "name": "waits", "events": ["wait-held.**", "wait-ended.**"], "max-age-days": 7, "max-mib": 16 },
+    { "name": "mesh-delivery-builder-builds", "events": ["build.ended.**"], "max-age-days": 7, "max-mib": 16 },
     { "name": "mesh-delivery-builder-findings", "events": ["finding-written.*", "finding-cleared.*", "findings-stated.*"], "max-age-days": 7, "max-mib": 16 }
   ],
   "config": {