diff --git a/modules/mesh-delivery-builder/internal/build/run_test.go b/modules/mesh-delivery-builder/internal/build/run_test.go
index 2e927ef1..83c965e7 100644
--- a/modules/mesh-delivery-builder/internal/build/run_test.go
+++ b/modules/mesh-delivery-builder/internal/build/run_test.go
@@ -1403,8 +1403,7 @@ func aDoneKeyKeepsEachFormACountedNodeReads(t *testing.T) {
 					t.Errorf("%s %s: the want of %s is held", k.kind, row.name, node)
 				}
 			}
-			// mesh-sdk's referenceProblem does not yet know the holder's upstream/<host>/<path> naming (a request to the SDK's owner).
-			if _, err := delivery.EncodeBuilderBuild(delivery.BuilderBuild{State: delivery.BuildDone, Manifest: strings.TrimPrefix(digest, "sha256:"), Artifacts: []delivery.BuiltArtifact{a}, Needs: needs}); err != nil && k.kind != "upstream" {
+			if _, err := delivery.EncodeBuilderBuild(delivery.BuilderBuild{State: delivery.BuildDone, Manifest: strings.TrimPrefix(digest, "sha256:"), Artifacts: []delivery.BuiltArtifact{a}, Needs: needs}); err != nil {
 				t.Errorf("%s %s: %v", k.kind, row.name, err)
 			}
 		}
diff --git a/sdk/forms/forms.go b/sdk/forms/forms.go
index 4183ef84..8f447800 100644
--- a/sdk/forms/forms.go
+++ b/sdk/forms/forms.go
@@ -36,27 +36,11 @@ const (
 // <seat>/<module>/<artifact>@sha256:<digest> (novox/hq ADR 0605 §9; catalogue.SeatReference, read back by
 // catalogue.InRegistrySeat): a bundle or an archive through oci-artifact-registry, an image through
 // container-image-registry, and an upstream copy through container-image-registry under the holder's own naming,
-// container-image-registry/upstream/<host>/<path>@sha256:<digest>. It is read by a node-engine that states
+// container-image-registry/upstream/<host>/<path>@sha256:<digest> (catalogue.InUpstream). It is read by a node-engine that states
 // form:seat-reference (catalogue.ReferenceFormSeat). Not a first form: an engine stating nothing reads the artifact in the
 // older artifact-store form, which it derives (Older).
 const FormSeatReference = catalogue.ReferenceFormSeat
 
-// upstreamPrefix opens an upstream copy's name in the image seat's answer: the holder's naming, upstream/<host>/<path>.
-const upstreamPrefix = "upstream/"
-
-// inSeatReference reads a reference in the seat form: the seat it came through and the name and digest after it,
-// <module>/<artifact>@<digest> (or upstream/<host>/<path>@<digest> for an upstream copy of the image seat).
-func inSeatReference(r string) (seat, path string, ok bool) {
-	if seat, path, ok = catalogue.InRegistrySeat(r); ok {
-		return seat, path, true
-	}
-	rest, found := strings.CutPrefix(r, catalogue.ContainerImageRegistrySeat+"/"+upstreamPrefix)
-	if !found || !strings.Contains(rest, "@sha256:") {
-		return "", "", false
-	}
-	return catalogue.ContainerImageRegistrySeat, upstreamPrefix + rest, true
-}
-
 // ArtifactForm is one reference form: its name, whether it is a first form, the artifact kinds it names, how a
 // reference is told to be in it, and, for a form that names the same artifact an older form does, that older reference
 // (Older, nil when it derives none): the old-form window writes it beside the answered one (ADR 0624 §1, §3).
@@ -84,19 +68,13 @@ var Current = ArtifactForms{
 	{Name: FormPackageVersion, First: true, Is: func(r string) bool { return strings.LastIndex(r, "@") > 0 && !strings.Contains(r, "@sha256:") },
 		Kinds: []string{catalogue.ArtifactPackage}},
 	{Name: FormSeatReference, Kinds: []string{catalogue.ArtifactBundle, catalogue.ArtifactArchive, catalogue.ArtifactImage, catalogue.ArtifactUpstream},
-		Is: func(r string) bool {
-			seat, _, ok := inSeatReference(r)
-			return ok && (seat == catalogue.OciArtifactRegistrySeat || seat == catalogue.ContainerImageRegistrySeat)
-		},
-		// The same artifact in the artifact store's form: oci-artifact-registry/<m>/<a>@<d> is artifact-store://<m>/<a>/blobs/<d>;
-		// container-image-registry/<m>/<a>@<d> (an upstream copy's upstream/<h>/<p>@<d> likewise) is artifact-store://<m>/<a>@<d>.
+		Is: func(r string) bool { _, _, ok := catalogue.InRegistrySeat(r); return ok },
+		// The same artifact in the artifact store's form (catalogue.InArtifactStore): oci-artifact-registry/<m>/<a>@<d> is
+		// artifact-store://<m>/<a>/blobs/<d>; container-image-registry/<m>/<a>@<d> is artifact-store://<m>/<a>@<d>, and an
+		// upstream copy's container-image-registry/upstream/<h>/<p>@<d> is artifact-store://upstream/<h>/<p>@<d>.
 		Older: func(r string) string {
-			seat, rest, _ := inSeatReference(r)
-			if seat == catalogue.OciArtifactRegistrySeat {
-				path, _ := catalogue.InArtifactStore(r)
-				return catalogue.ArtifactStoreScheme + path
-			}
-			return catalogue.ArtifactStoreScheme + rest
+			path, _ := catalogue.InArtifactStore(r)
+			return catalogue.ArtifactStoreScheme + path
 		}},
 }