G-catalog-B 6: on registry 2.8.3 a shared-digest tagged version's remove answers and says kept

Saying removed for a version the store still holds told the builder something false. remove now answers
kept with the reason shared-digest and the other tags naming its digest, removed false, and says the
seat's event kept with them (mesh-contracts' shared registry part); the builder raises no retry.

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

modules/distribution/cmd/distribution-tools/contract_test.go

@@ -49,7 +49,7 @@ func TestTheVerbsSpeakTheSeatsContract(t *testing.T) {
 	if seen != 14 {
 		t.Errorf("%d seat verbs served, want 14 (8 on the image seat, 6 on the artifact seat)", seen)
 	}
-	for event, want := range map[string]any{holder.EventPublished: &reg.Outcome{}, holder.EventHeld: &reg.Hold{}, holder.EventReleased: &reg.Hold{}} {
+	for event, want := range map[string]any{holder.EventPublished: &reg.Outcome{}, holder.EventKept: &reg.KeptEvent{}, holder.EventHeld: &reg.Hold{}, holder.EventReleased: &reg.Hold{}} {
 		b, _ := json.Marshal(eventBody(event, holder.Event{Name: "m/a", Kind: holder.KindArchive, Digest: "sha256:aa", Holder: holder.Self, By: "x.artifact-store-tools"}))
 		dec := json.NewDecoder(bytes.NewReader(b))
 		dec.DisallowUnknownFields()