DLV-B2 sdk: a build ask names each artifact's seat and the version the builder gave it (design 51, A3's request)

AskArtifact.Seat, one of the four registry seats, and AskArtifact.Version, which names a seat; an older reader ignores
both.

Claude-Session: https://claude.ai/code/session_01JG73KJNrH5EgFXMKKYSrig

go/delivery/builder_reference_test.go

@@ -148,4 +148,3 @@ func TestADoneKeyWithNoArtifactIsReferenced(t *testing.T) {
 		t.Fatalf("Referenced = %v, %v; want true", ok, missing)
 	}
 }
-

go/delivery/stepasks.go

@@ -7,9 +7,12 @@ import (
 	"fmt"
 	"path"
 	"regexp"
+	"slices"
 	"sort"
 	"strings"
 	"time"
+
+	contractseats "git.novox.be/novox/mesh-contracts/go/seats"
 )
 
 // **Asks: a build or a check step is a message a build node pulls when it has a free slot** (novox/hq ADR 0525, as
@@ -340,6 +343,15 @@ type BuildJob struct {
 type AskArtifact struct {
 	Artifact string `json:"artifact"`
 	From     string `json:"from,omitempty"`
+	// Seat is the registry seat the artifact is published through (design 51 *Publishing*): npm-package-registry or
+	// go-package-registry for a package, container-image-registry for an image or an upstream copy,
+	// oci-artifact-registry for a bundle or an archive. Absent for an ask written before the registry milestone, which
+	// its build module pushes as before.
+	Seat string `json:"seat,omitempty"`
+	// Version is the version the builder gave the artifact at the trunk's claim (design 51 *The versions*), which the
+	// build module names in the seat's publish; absent for a candidate's build and for a bundle or an archive published
+	// by its digest alone (ADR 0617 §1).
+	Version string `json:"version,omitempty"`
 }
 
 // CheckJob is a check ask's job, the levels of one check (ADR 0525 §3): fetch the head merged onto its trunk once, then
@@ -453,6 +465,10 @@ func (c ComposeJob) check(id string) error {
 	return nil
 }
 
+// registrySeats are the seats an artifact is published through (ADR 0605 §1).
+var registrySeats = []string{contractseats.NpmPackageRegistry, contractseats.GoPackageRegistry,
+	contractseats.ContainerImageRegistry, contractseats.OciArtifactRegistry}
+
 func (b BuildJob) check(id string) error {
 	if err := checkName("module", b.Module); err != nil {
 		return err
@@ -465,6 +481,14 @@ func (b BuildJob) check(id string) error {
 		if err := checkName("artifact", a.Artifact); err != nil {
 			return err
 		}
+		if a.Seat != "" && !slices.Contains(registrySeats, a.Seat) {
+			return fmt.Errorf("delivery: the build ask %s publishes %s through %q, which is no registry seat (%s)", id,
+				a.Artifact, a.Seat, strings.Join(registrySeats, ", "))
+		}
+		if a.Version != "" && a.Seat == "" {
+			return fmt.Errorf("delivery: the build ask %s gives %s the version %s and names no seat to publish it through",
+				id, a.Artifact, a.Version)
+		}
 		fetch = fetch || a.From == ""
 	}
 	if fetch {

go/delivery/stepasks_test.go

@@ -15,9 +15,10 @@ func buildAsk() StepAsk {
 	return StepAsk{ID: "mh3k2x9qa1b2c3", Kind: AskDelivery, Language: AskGo, Asker: "mesh-delivery-builder",
 		At: time.Date(2026, 10, 23, 13, 0, 0, 0, time.UTC),
 		Build: &BuildJob{Module: "mesh-delivery-view", Path: "modules/mesh-delivery-view", FP: "ab12",
-			Fetch:     map[string]any{"repository": "novox/mesh-delivery", "commit": askCommit, "dir": "modules/mesh-delivery-view", "paths": []any{"cmd"}},
-			Artifacts: []AskArtifact{{Artifact: "bundle"}, {Artifact: "base", From: "registry/x@sha256:00"}},
-			Publish:   true, Toolchain: &ToolchainUsed{Version: "go1.26.0", Recipe: "3"}},
+			Fetch: map[string]any{"repository": "novox/mesh-delivery", "commit": askCommit, "dir": "modules/mesh-delivery-view", "paths": []any{"cmd"}},
+			Artifacts: []AskArtifact{{Artifact: "bundle", Seat: "oci-artifact-registry", Version: "0.1.4"},
+				{Artifact: "base", From: "registry/x@sha256:00"}},
+			Publish: true, Toolchain: &ToolchainUsed{Version: "go1.26.0", Recipe: "3"}},
 		Packages: PackageVersions{"git.novox.be/novox/mesh-sdk/go": askCommit}}
 }
 
@@ -83,6 +84,15 @@ func TestAskRefusesUnknownKindAndLanguage(t *testing.T) {
 			t.Errorf("the node names %q: encoded", names)
 		}
 	}
+	// An artifact is published through a registry seat, and a version names the seat it is published through
+	// (design 51).
+	for _, art := range []AskArtifact{{Artifact: "bundle", Seat: "mesh-artifact-store"}, {Artifact: "bundle", Version: "0.1.4"}} {
+		a := buildAsk()
+		a.Build.Artifacts = []AskArtifact{art}
+		if _, err := EncodeStepAsk(a); err == nil {
+			t.Errorf("the artifact %+v: encoded", art)
+		}
+	}
 	// A copy alone fetches nothing and needs no path.
 	a := buildAsk()
 	a.Build.Fetch, a.Build.Path, a.Build.Artifacts = nil, "", []AskArtifact{{Artifact: "base", From: "registry/x@sha256:00"}}