diff --git a/go/delivery/published_packages_test.go b/go/delivery/published_packages_test.go
index 773f022..a971dc9 100644
--- a/go/delivery/published_packages_test.go
+++ b/go/delivery/published_packages_test.go
@@ -105,8 +105,21 @@ func TestPublishedPackagesAndImportsRoundTripAndRefuse(t *testing.T) {
 		}
 	}
 	var answer BuildAnswer
-	if err := json.Unmarshal([]byte(`{"artifacts":[],"imports":["`+sdk+`"]}`), &answer); err != nil || len(answer.Imports) != 1 {
-		t.Fatalf("build answer imports: %v, %v", err, answer.Imports)
+	if err := json.Unmarshal([]byte(`{"artifacts":[],"imports":["`+sdk+`"],"out-of-step":["go/seats/x/contract.go"]}`), &answer); err != nil ||
+		len(answer.Imports) != 1 || !reflect.DeepEqual(answer.OutOfStep, []string{"go/seats/x/contract.go"}) {
+		t.Fatalf("build answer imports and files out of step: %v, %v, %v", err, answer.Imports, answer.OutOfStep)
+	}
+	// The builder's version.numbered, as a build module consumes it: the builder's own body whole, and its subject.
+	numbered := VersionNumbered{Name: "mesh-sdk/go", Kind: "package", Version: "0.1.7", Module: "mesh-sdk", Fingerprint: "src2:x",
+		Commit: commit, Digest: "sha256:d", Seat: "go-package-registry", Head: commit, Again: "2026-11-04T15:00:00Z"}
+	if raw, err := EncodeVersionNumbered(numbered); err != nil {
+		t.Errorf("numbered refused: %v", err)
+	} else if back, err := DecodeVersionNumbered(raw); err != nil || back != numbered ||
+		!strings.Contains(string(raw), `"fingerprint":"src2:x"`) || VersionNumberedSubject != "mesh.mod.mesh-delivery-builder.event.version.numbered" {
+		t.Errorf("numbered round trip: %+v, %v, %s", back, err, raw)
+	}
+	if _, err := DecodeVersionNumbered([]byte(`{"name":"mesh-sdk/go","version":"0.1.7"}`)); err == nil {
+		t.Error("a numbered version naming no build is read")
 	}
 	if err := CheckImports([]string{"fmt"}); err == nil {
 		t.Error("CheckImports takes a standard package")
diff --git a/go/delivery/stepasks.go b/go/delivery/stepasks.go
index 110cd21..a4ddb74 100644
--- a/go/delivery/stepasks.go
+++ b/go/delivery/stepasks.go
@@ -588,6 +588,10 @@ type BuildAnswer struct {
 	// once (novox/hq ADR 0593 §2): a Go build module reports them, the builder carries them onto the build's end
 	// (BuildLogEntry.Imports). Absent from a build module that reports none.
 	Imports []string `json:"imports,omitempty"`
+	// OutOfStep are the generated files the build's compare found out of step with what their generator writes (the test
+	// step's `out-of-step`, answered by a trunk build's ask too): the builder carries them onto the build's end
+	// (BuildLogEntry.OutOfStep). Absent when none is, or from a build module that compares none.
+	OutOfStep []string `json:"out-of-step,omitempty"`
 }
 
 // AskBuilt is one artifact a build ask built.
diff --git a/go/delivery/version_numbered.go b/go/delivery/version_numbered.go
new file mode 100644
index 0000000..634cb84
--- /dev/null
+++ b/go/delivery/version_numbered.go
@@ -0,0 +1,57 @@
+package delivery
+
+import (
+	"encoding/json"
+	"fmt"
+)
+
+// The builder's event version.numbered (design 51 *Events of the builder*, *The floor*): said once per version the builder
+// numbers, on its own family `version` (seven days), apart from its builds' ends, so a waiter on a build's end does not
+// wake on it. A build module consumes it to publish a build's version with the held digest, which stores nothing.
+const (
+	// VersionNumberedEvent is the event's local name.
+	VersionNumberedEvent = "version.numbered"
+	// VersionNumberedSubject is its subject, as a consumer's filter names it.
+	VersionNumberedSubject = "mesh.mod." + BuilderModule + ".event." + VersionNumberedEvent
+)
+
+// VersionNumbered is the body of VersionNumberedEvent: a numbered version of a name, the build it was numbered for, and
+// what the build module needs to publish it.
+type VersionNumbered struct {
+	// Name is the numbered name, as builder_versions lists it; Kind its artifact's kind.
+	Name    string `json:"name"`
+	Kind    string `json:"kind"`
+	Version string `json:"version"`
+	Tag     string `json:"tag,omitempty"`
+	// Module and Fingerprint are the build the version was numbered for; Commit its source commit.
+	Module      string `json:"module"`
+	Fingerprint string `json:"fingerprint"`
+	Commit      string `json:"commit,omitempty"`
+	// Digest is the built artifact's, when the build held one; Seat the registry seat it is published through.
+	Digest string `json:"digest,omitempty"`
+	Seat   string `json:"seat,omitempty"`
+	// Head is the head the version answers, when it answers a tag ask.
+	Head string `json:"head,omitempty"`
+	// Again is when builder_publish_again said it once more, so the bus's dedup does not drop it.
+	Again string `json:"again,omitempty"`
+}
+
+// EncodeVersionNumbered writes the body, refusing one that names no name, version, module or fingerprint.
+func EncodeVersionNumbered(n VersionNumbered) ([]byte, error) {
+	if n.Name == "" || n.Version == "" || n.Module == "" || n.Fingerprint == "" {
+		return nil, fmt.Errorf("delivery: %s names its name, version, module and fingerprint", VersionNumberedEvent)
+	}
+	return json.Marshal(n)
+}
+
+// DecodeVersionNumbered reads the body, with the same refusal.
+func DecodeVersionNumbered(data []byte) (VersionNumbered, error) {
+	var n VersionNumbered
+	if err := json.Unmarshal(data, &n); err != nil {
+		return VersionNumbered{}, fmt.Errorf("delivery: %s is not readable: %w", VersionNumberedEvent, err)
+	}
+	if _, err := EncodeVersionNumbered(n); err != nil {
+		return VersionNumbered{}, err
+	}
+	return n, nil
+}