diff --git a/modules/mesh-delivery-builder/builds/builds.go b/modules/mesh-delivery-builder/builds/builds.go
index 19299958..f282bb74 100644
--- a/modules/mesh-delivery-builder/builds/builds.go
+++ b/modules/mesh-delivery-builder/builds/builds.go
@@ -12,7 +12,7 @@ import (
 	"strings"
 
 	"git.novox.be/novox/mesh-delivery/contracts/go/clients/containerimageregistryclient/reference"
-	"git.novox.be/novox/mesh-delivery/contracts/go/clients/meshcatalogclient"
+	"git.novox.be/novox/mesh-delivery/contracts/go/clients/meshcatalogkey"
 	"git.novox.be/novox/mesh-delivery/contracts/go/seats/containerimageregistry"
 	"git.novox.be/novox/mesh-delivery/contracts/go/seats/ociartifactregistry"
 	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-builder/builds/forms"
@@ -63,13 +63,13 @@ const (
 )
 
 // BuilderBuildKey is the key, in BuilderBuildsBucket, of a module's build at a fingerprint: `<module>.<hex>`, the hex
-// being the fingerprint's key part (meshcatalogclient.KeyPart), since a bus key may not hold ':'. A module holding a dot or a
+// being the fingerprint's key part (meshcatalogkey.KeyPart), since a bus key may not hold ':'. A module holding a dot or a
 // character a key refuses, and a fingerprint not of the new form, are refused, naming them.
 func BuilderBuildKey(module, fp string) (string, error) {
 	if err := keys.CheckName("module", module); err != nil {
 		return "", err
 	}
-	part, err := meshcatalogclient.KeyPart(fp)
+	part, err := meshcatalogkey.KeyPart(fp)
 	if err != nil {
 		return "", err
 	}
@@ -85,7 +85,7 @@ func ParseBuilderBuildKey(key string) (module, fp string, err error) {
 	if err := keys.CheckName("module", module); err != nil {
 		return "", "", fmt.Errorf("builds: %q is not a builder build key: %w", key, err)
 	}
-	if fp, err = meshcatalogclient.ParseKeyPart(part); err != nil {
+	if fp, err = meshcatalogkey.ParseKeyPart(part); err != nil {
 		return "", "", fmt.Errorf("builds: %q is not a builder build key: %w", key, err)
 	}
 	return module, fp, nil
@@ -237,9 +237,16 @@ type BuilderBuild struct {
 	// node-engine, beside the ones its manifest needs (novox/hq ADR 0618 §1). A reader that does not know the field
 	// reads the build as needing none.
 	Needs []string `json:"needs,omitempty"`
+	// KeptOn is, on a done key only, the build node that keeps the build instead of storing it through the seat
+	// oci-artifact-registry (design 47 G §671): every artifact of the build is kept there, each with its digest in
+	// Artifacts. A build not kept names none; the builder carries it onto the build's end (BuildLogEntry.KeptOn).
+	KeptOn string `json:"kept-on,omitempty"`
 }
 
 func (b BuilderBuild) check() error {
+	if b.KeptOn != "" && b.State != BuildDone {
+		return fmt.Errorf("builds: a build is kept on a done key alone, this one is %s", b.State)
+	}
 	if err := trunk.CheckImports(b.Imports); err != nil {
 		return err
 	}
diff --git a/modules/mesh-delivery-builder/builds/log.go b/modules/mesh-delivery-builder/builds/log.go
index 0c59e696..455000d2 100644
--- a/modules/mesh-delivery-builder/builds/log.go
+++ b/modules/mesh-delivery-builder/builds/log.go
@@ -67,6 +67,9 @@ type BuildLogEntry struct {
 	Manifest   string          `json:"manifest,omitempty"`
 	Against    []string        `json:"against,omitempty"`
 	Made       []BuiltArtifact `json:"made,omitempty"`
+	// KeptOn is, at the end of a kept build, the build node that keeps it, once for the build (design 47 G §671): every
+	// artifact in Made is kept there, with its digest. A build not kept carries none.
+	KeptOn string `json:"kept-on,omitempty"`
 	// Imports are, at a build's end, the mesh packages (import paths) the built programs import, their tests left out,
 	// sorted and each once, as the build module answered them (BuildAnswer.Imports; novox/hq ADR 0593 §2): the indexer
 	// keeps them on the module (KeptInputs2.Imports) when the build's fingerprint is the module's.
diff --git a/modules/mesh-delivery-builder/internal/build/imports_test.go b/modules/mesh-delivery-builder/internal/build/imports_test.go
index 20ee96e5..ac12fc0f 100644
--- a/modules/mesh-delivery-builder/internal/build/imports_test.go
+++ b/modules/mesh-delivery-builder/internal/build/imports_test.go
@@ -82,3 +82,31 @@ func outOfStepFilesABuildAnswersReachTheLog(t *testing.T) {
 		})
 	}
 }
+
+// Design 47 G §671: a build the build node kept instead of storing it, which answers its digest and no reference, is done,
+// and its end in the log names the node that keeps it once; a build not kept names none.
+func aKeptBuildNamesItsNodeInItsEnd(t *testing.T) {
+	r := newRig(t, goBundle)
+	r.asks.Answer = func(a buildstep.StepAsk) buildstep.Step {
+		step := r.answer(a)
+		var answer buildstep.BuildAnswer
+		if err := json.Unmarshal(step.Result, &answer); err == nil && a.Language == "go" && len(answer.Artifacts) > 0 {
+			for i := range answer.Artifacts {
+				answer.Artifacts[i].Reference = ""
+			}
+			answer.Kept = strings.TrimPrefix(answer.Artifacts[0].Digest, "sha256:")
+			step.Result, _ = json.Marshal(answer)
+		}
+		return step
+	}
+	var logged []builds.BuildLogEntry
+	var mu sync.Mutex
+	r.b.Node, r.b.Log = "novox", func(e builds.BuildLogEntry) { mu.Lock(); logged = append(logged, e); mu.Unlock() }
+	v := r.consider(t, "modules/m")
+	if v.State != builds.BuildDone || v.KeptOn == "" {
+		t.Fatalf("done key %+v, want it done and kept on its node", v)
+	}
+	if len(logged) != 2 || logged[1].KeptOn != v.KeptOn || logged[0].KeptOn != "" {
+		t.Fatalf("log %+v, want kept-on %q on the end alone", logged, v.KeptOn)
+	}
+}
diff --git a/modules/mesh-delivery-builder/internal/build/run.go b/modules/mesh-delivery-builder/internal/build/run.go
index baaf480c..e17baad3 100644
--- a/modules/mesh-delivery-builder/internal/build/run.go
+++ b/modules/mesh-delivery-builder/internal/build/run.go
@@ -651,6 +651,7 @@ type lane struct {
 	digests      map[string]string // artifact -> digest
 	references   map[string]string // artifact -> the reference an image was pushed to (a trunk build only)
 	imports      []string          // the mesh packages the lane's programs import, as its build module answered them
+	kept         string            // the digest of the artifact the build node kept instead of storing it (BuildAnswer.Kept), else empty
 	outOfStep    []string          // the generated files its build module's compare found out of step, passed or failed
 	err          error
 }
@@ -763,7 +764,7 @@ func (b *Builder) build(ctx context.Context, module string, m meshcatalog.Module
 				continue
 			}
 			r := l.references[t.Artifact]
-			if r == "" && stored(t.Kind) {
+			if r == "" && stored(t.Kind) && (l.kept == "" || strings.TrimPrefix(d, "sha256:") != l.kept) {
 				// A bundle, an archive or an upstream copy is done only when its push was answered with where it is (ADR 0498
 				// clause 1); a candidate's included (clause 3).
 				return failed("%s%s on %s: the build answered no reference, so its push to the artifact store was not answered", builds.NotStored, t.Artifact, l.node)
@@ -796,6 +797,11 @@ func (b *Builder) build(ctx context.Context, module string, m meshcatalog.Module
 	}
 	done := builds.BuilderBuild{State: builds.BuildDone, By: b.Claimer.By, Manifest: m.Manifest, Step: step, Artifacts: artifacts, Toolchains: used,
 		Imports: importsOf(lanes), Needs: forms.Current.Needs(artifacts)} // the forms it is written in (ADR 0618 §1)
+	for _, l := range lanes {
+		if l.kept != "" {
+			done.KeptOn = l.node // design 47 G §671: the build node that keeps the build
+		}
+	}
 	if _, err := builds.EncodeBuilderBuild(done); err != nil {
 		// A reference the build module answered that does not name the artifact and its digest is no reference.
 		return failed("%s%v", builds.NotStored, err)
@@ -1008,6 +1014,7 @@ func (b *Builder) runLane(ctx context.Context, l *lane, repository string, m mes
 		return
 	}
 	l.imports = answer.Imports
+	l.kept = answer.Kept
 	built := map[string]sdkstep.AskBuilt{}
 	for _, a := range answer.Artifacts {
 		built[a.Artifact] = a
@@ -1092,6 +1099,7 @@ func LogEnded(module string, m meshcatalog.ModulesByModuleValue, ref, by string,
 		e.Against = append([]string(nil), m.Inputs2.Bases...)
 	}
 	e.Made = append([]builds.BuiltArtifact(nil), result.Artifacts...)
+	e.KeptOn = result.KeptOn
 	e.Imports = append([]string(nil), result.Imports...) // the indexer keeps them on the module (novox/hq ADR 0593 §2)
 	e.Error, e.Step = result.Error, result.Step          // a failed build's reason, not only its outcome
 	return e
diff --git a/modules/mesh-delivery-builder/internal/build/run_test.go b/modules/mesh-delivery-builder/internal/build/run_test.go
index cfe21eaa..0339f41e 100644
--- a/modules/mesh-delivery-builder/internal/build/run_test.go
+++ b/modules/mesh-delivery-builder/internal/build/run_test.go
@@ -230,6 +230,7 @@ var (
 
 func TestABundleAndAnArchiveAreBuiltOnOneNodeAndDone(t *testing.T) { // 1607/AC7, ADR 0478 clauses 1, 4
 	t.Run("the imports a build answers reach the done key and the log", importsABuildAnswersReachTheDoneKeyAndTheLog)
+	t.Run("a kept build names its node in its end", aKeptBuildNamesItsNodeInItsEnd)
 	t.Run("the out-of-step files a build answers reach the log", outOfStepFilesABuildAnswersReachTheLog)
 	t.Run("ADR 0624: a done key keeps each form a counted node reads", aDoneKeyKeepsEachFormACountedNodeReads)
 	r := newRig(t, goBundle, archiveA, tsBundle)