diff --git a/modules/mesh-delivery-builder/internal/build/reserve_test.go b/modules/mesh-delivery-builder/internal/build/reserve_test.go
index 8bd84216..d0979f55 100644
--- a/modules/mesh-delivery-builder/internal/build/reserve_test.go
+++ b/modules/mesh-delivery-builder/internal/build/reserve_test.go
@@ -204,3 +204,37 @@ func TestAReservedBuildKeepsWhatItsStepResolvedAndWasBuiltWith(t *testing.T) {
 		t.Errorf("journal %q, want the package no edge names said", journal)
 	}
 }
+
+// TestAModuleWhoseOnlyArtifactIsAGoPackageIsBuiltUnderItsReservedVersion: design 47 G §370 — a module whose one artifact is
+// a Go package (mesh-wireguard's go-overlay) is planned on the Go build seat, its ask carries the reserved version and names
+// the seat go-package-registry the package is published and tagged through, and the build is done; a build reserving none
+// names no seat.
+func TestAModuleWhoseOnlyArtifactIsAGoPackageIsBuiltUnderItsReservedVersion(t *testing.T) {
+	goPackage := catalogue.Artifact{Name: "go-overlay", Kind: catalogue.ArtifactPackage, Language: "go", Paths: []string{"go"}}
+	for _, c := range []struct {
+		name, series, version, seat string
+	}{
+		{"reserved", "0.1", "0.1.5", versions.SeatGoPackages},
+		{"reserving none", "1", "", ""},
+	} {
+		t.Run(c.name, func(t *testing.T) {
+			r := newRig(t, goPackage)
+			r.mf.byDigest[mdigest('a')] = catalogue.Manifest{Module: "m", Version: c.series, Build: &catalogue.Build{Artifacts: []catalogue.Artifact{goPackage}}}
+			r.b.Reserved = &fakeReservations{filled: true}
+			r.bm.packages["go-overlay"] = "git.novox.be/novox/mesh-networking/go@v0.1.5" // the Go build module's published reference
+			var asked []buildstep.StepAsk
+			r.asks.Answer = func(a buildstep.StepAsk) buildstep.Step {
+				asked = append(asked, a)
+				return r.answer(a)
+			}
+			v := r.consider(t, "modules/m")
+			if v.State != builds.BuildDone {
+				t.Fatalf("state %s (%s), want done", v.State, v.Error)
+			}
+			if len(asked) != 1 || asked[0].Language != buildstep.AskGo || asked[0].Version != c.version || asked[0].Build == nil ||
+				len(asked[0].Build.Artifacts) != 1 || asked[0].Build.Artifacts[0] != (buildstep.AskArtifact{Artifact: "go-overlay", Seat: c.seat}) {
+				t.Fatalf("asks %+v, want one Go ask with version %q naming go-overlay on seat %q", asked, c.version, c.seat)
+			}
+		})
+	}
+}
diff --git a/modules/mesh-delivery-builder/internal/build/run.go b/modules/mesh-delivery-builder/internal/build/run.go
index 471e8b42..23a56aa7 100644
--- a/modules/mesh-delivery-builder/internal/build/run.go
+++ b/modules/mesh-delivery-builder/internal/build/run.go
@@ -1055,6 +1055,10 @@ func (b *Builder) runLane(ctx context.Context, l *lane, repository string, m mes
 		a := sdkstep.AskArtifact{Artifact: t.Artifact}
 		if t.Kind == catalogue.ArtifactUpstream {
 			a.From = t.From // the copy runs no code of a change: the module's name, the artifact and its pin
+		} else if seat, _, ok := versions.SeatOf(t.Kind, t.Language); ok && l.version != "" {
+			// A build under a reserved version names the registry seat each artifact is published through, so a Go package is
+			// published and tagged under it (design 47 G §370; design 51 *Publishing*).
+			a.Seat = seat
 		}
 		job.Artifacts = append(job.Artifacts, a)
 	}
diff --git a/modules/mesh-delivery-sdk/steprun/askrun.go b/modules/mesh-delivery-sdk/steprun/askrun.go
index 7305f33f..a0b95356 100644
--- a/modules/mesh-delivery-sdk/steprun/askrun.go
+++ b/modules/mesh-delivery-sdk/steprun/askrun.go
@@ -61,7 +61,7 @@ func RunAsk(ctx context.Context, steps AskSteps, ask sdkstep.StepAsk) (any, erro
 	if ask.Build != nil {
 		job := *ask.Build
 		job.Fetch = withPackages(job.Fetch, ask.Packages)
-		return steps.build(ctx, job)
+		return steps.build(ctx, job, ask.Version)
 	}
 	if ask.Step != nil {
 		return steps.runStep(ctx, ask)
@@ -167,7 +167,9 @@ func (s AskSteps) onToolchain(ctx context.Context, want *sdkstep.ToolchainUsed)
 	return &tc, nil
 }
 
-func (s AskSteps) build(ctx context.Context, job sdkstep.BuildJob) (any, error) {
+// build runs a build job; version is the version the ask carries (design 47 G §573), which each artifact's build is given
+// as its argument version, the build's MESH_VERSION (§370), unless the artifact names its own.
+func (s AskSteps) build(ctx context.Context, job sdkstep.BuildJob, version string) (any, error) {
 	answer := sdkstep.BuildAnswer{}
 	tc, err := s.onToolchain(ctx, job.Toolchain)
 	if err != nil {
@@ -240,6 +242,8 @@ func (s AskSteps) build(ctx context.Context, job sdkstep.BuildJob) (any, error)
 			}
 			if a.Version != "" {
 				args["version"] = a.Version
+			} else if version != "" {
+				args["version"] = version
 			}
 			Phase(ctx, "build "+a.Artifact)
 			out, err = s.Build(ctx, args)
diff --git a/modules/mesh-delivery-sdk/steprun/askrun_test.go b/modules/mesh-delivery-sdk/steprun/askrun_test.go
index 6fb00e69..3662862d 100644
--- a/modules/mesh-delivery-sdk/steprun/askrun_test.go
+++ b/modules/mesh-delivery-sdk/steprun/askrun_test.go
@@ -89,6 +89,8 @@ func TestRunAskBuilds(t *testing.T) {
 		Fetch:     &sdkstep.Fetch{Repository: "novox/x", Commit: runCommit},
 		Artifacts: []sdkstep.AskArtifact{{Artifact: "base", From: "registry/b@sha256:00"}, {Artifact: "bundle"}, {Artifact: "lib", Seat: "go-package-registry", Version: "v0.1.15"}}})
 	a.Packages = sdkstep.PackageVersions{"git.novox.be/novox/mesh-sdk/go": runCommit}
+	// Design 47 G §573, §370: the version the ask carries reaches each artifact's build; one the artifact names stays its own.
+	a.Version = "0.1.16"
 	out, err := RunAsk(context.Background(), steps, a)
 	if err != nil {
 		t.Fatal(err)
@@ -99,7 +101,7 @@ func TestRunAskBuilds(t *testing.T) {
 	got := strings.Join(r.calls, "\n")
 	want := `copy {"artifact":"base","from":"registry/b@sha256:00","module":"m"}
 fetch {"commit":"` + runCommit + `","packages":{"git.novox.be/novox/mesh-sdk/go":"` + runCommit + `"},"repository":"novox/x"}
-build {"artifact":"bundle","module":"modules/m","publish":true,"workspace":"/w/1"}
+build {"artifact":"bundle","module":"modules/m","publish":true,"version":"0.1.16","workspace":"/w/1"}
 build {"artifact":"lib","module":"modules/m","publish":true,"seat":"go-package-registry","version":"v0.1.15","workspace":"/w/1"}
 imports {"module":"modules/m","workspace":"/w/1"}`
 	if got != want {