SDK-2: the seat's reference form is a reader capability a node-engine states, form:seat-reference (ADR 0618 §1, ADR 0624 §1)

catalogue.ReferenceFormSeat joins ManifestReads, so the builder compares it with a node record's stated reads (A3's
request 3); the older forms are the baseline's and the builder's to name (lead-47's delivery forms on
feat/adr0618-reads, where FormRegistry's match must leave this form out when the two meet).

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

go/catalogue/manifest_reads.go

@@ -37,6 +37,16 @@ const (
 var referenceForms = []string{"access", "backup", "bound", "collected", "config", "consumer", "consumers",
 	"contribution", "dir", "machine", "port", "seat", "secret", "setting"}
 
+// ReferenceFormSeat names the reference form a registry seat answers for a build's artifact,
+// `<seat>/<module>/<artifact>@sha256:<digest>` (novox/hq ADR 0605 §9; InRegistrySeat), as the reader capability
+// `form:seat-reference` a node-engine built with this contract states (ADR 0618 §1, ADR 0624 §1): the builder writes it
+// into a build key only for the nodes whose engines state it. The older reference forms a node-engine read before any
+// stated what it reads are the baseline's; they are the builder's to name (delivery's artifact forms).
+const ReferenceFormSeat = "seat-reference"
+
+// artifactReferenceForms are the reference forms of a build's artifacts this contract reads beyond the baseline's.
+var artifactReferenceForms = []string{ReferenceFormSeat}
+
 // manifestTopWords are the top-level keys Manifest.UnmarshalJSON reads apart from the fields of manifestFields: each
 // read whole, its inside a map of the module's own names (requirements, local names) and values, no words of the
 // contract's beneath it. `requires` and `config` are read as their fields are (manifestNeeds).
@@ -60,6 +70,9 @@ func ManifestReads() []string {
 	for _, f := range referenceForms {
 		set[ReadForm+f] = true
 	}
+	for _, f := range artifactReferenceForms {
+		set[ReadForm+f] = true
+	}
 	for _, s := range DefaultSeats() {
 		set[ReadSeat+s.Name] = true
 	}

go/catalogue/own_manifest_test.go

@@ -42,7 +42,9 @@ func TestOwnManifestUsesNoWordTheRunningControllerRefuses(t *testing.T) {
 			t.Errorf("the baseline's %s is no reader capability of this contract", b)
 		}
 	}
-	for _, want := range []string{"word:tool-runner", "word:core-credentials", "word:bus-state", "word:bus-state.storage"} {
+	for _, want := range []string{"word:tool-runner", "word:core-credentials", "word:bus-state", "word:bus-state.storage",
+		// The reference form a registry seat answers (ADR 0605 §9), and the seats the registry milestone adds.
+		ReadForm + ReferenceFormSeat, "seat:go-package-registry", "seat:container-image-registry", "seat:oci-artifact-registry"} {
 		if !slices.Contains(added, want) {
 			t.Errorf("%s is in the baseline, or not read: added since it are %v", want, added)
 		}