Carry the catalogue's predefined list on the bridge's merged message, so the indexer keeps it without the controller's mirror (issue 1953 L5-D1, ADR 0565 §2)

go/delivery/forge_inputs_test.go

@@ -33,6 +33,22 @@ func TestForgeMergedCarriesManifestsAndLocks(t *testing.T) {
 	if got.Manifests["a"] != oddManifest || !SameForge(got, withV(f)) {
 		t.Errorf("the message changed on the way: %q", got.Manifests["a"])
 	}
+	// ADR 0565 §2 (issue 1953 D1): a merged message carries the predefined list exact, or says the merge holds none; a
+	// pull message carries neither.
+	f.Predefined = []byte(`{"domain":{"type":"string"}}`)
+	if data, err := EncodeForge(f); err != nil {
+		t.Fatal(err)
+	} else if got, err := DecodeForge(data); err != nil || string(got.Predefined) != `{"domain":{"type":"string"}}` {
+		t.Errorf("the predefined list read back as %s, %v", got.Predefined, err)
+	}
+	f.Predefined, f.PredefinedRead = nil, true
+	if _, err := EncodeForge(f); err != nil {
+		t.Errorf("a merge holding no predefined list: %v", err)
+	}
+	pull := Forge{Kind: ForgePull, Repository: "novox/mesh-sdk", Number: 1, Head: "h", Action: PullOpened, PredefinedRead: true}
+	if _, err := EncodeForge(pull); err == nil || !strings.Contains(err.Error(), "only a merged message") {
+		t.Errorf("a pull message carrying the predefined list: %v", err)
+	}
 }
 
 func withV(f Forge) Forge { f.V = Version; return f }
@@ -50,6 +66,9 @@ func TestForgeMergedRefusesBadInputs(t *testing.T) {
 		// No repository holds placement (ADR 0567 §11): a message carrying placement files is refused, on a merge or a pull.
 		"placement files": {func(f *Forge) { f.RetiredPlacements = []byte(`{"anchor":"{}"}`) }, "mesh-placement"},
 		"placements read": {func(f *Forge) { f.RetiredRead = true }, "mesh-placement"},
+		// ADR 0565 §2 (issue 1953 D1): the predefined list is one JSON object, said present or absent, never both.
+		"predefined not an object": {func(f *Forge) { f.Predefined = []byte(`["domain"]`) }, "one JSON object"},
+		"predefined both":          {func(f *Forge) { f.Predefined = []byte(`{}`); f.PredefinedRead = true }, "says the merge holds none"},
 	} {
 		f := mergedWithInputs()
 		tc.mut(&f)

go/delivery/source.go

@@ -542,6 +542,31 @@ type Forge struct {
 	// refused, loudly, rather than read with them dropped.
 	RetiredPlacements json.RawMessage `json:"placements,omitempty"`
 	RetiredRead       bool            `json:"placements-read,omitempty"`
+	// Predefined is the catalogue's predefined.json, exact, at the merge commit of a merged message (novox/hq ADR 0565
+	// §2): what the indexer keeps as its state `predefined`. PredefinedRead says the bridge read the merge and it holds
+	// no predefined.json. Carried on a merged message only; an older bridge sends neither, and the indexer keeps what it
+	// held.
+	Predefined     json.RawMessage `json:"predefined,omitempty"`
+	PredefinedRead bool            `json:"predefined-read,omitempty"`
+}
+
+// checkPredefined refuses the predefined list on anything but a merged message, a list that is not one JSON object, and
+// a list said both present and absent.
+func (f Forge) checkPredefined() error {
+	if len(f.Predefined) == 0 && !f.PredefinedRead {
+		return nil
+	}
+	if f.Kind != ForgeMerged {
+		return fmt.Errorf("delivery: only a merged message carries the predefined list, not a %s message", f.Kind)
+	}
+	if len(f.Predefined) > 0 && f.PredefinedRead {
+		return fmt.Errorf("delivery: a merged message carries the predefined list and says the merge holds none (predefined-read)")
+	}
+	var list map[string]json.RawMessage
+	if len(f.Predefined) > 0 && json.Unmarshal(f.Predefined, &list) != nil {
+		return fmt.Errorf("delivery: the predefined list a merged message carries is not one JSON object")
+	}
+	return nil
 }
 
 func (f Forge) check() error {
@@ -558,6 +583,9 @@ func (f Forge) check() error {
 		return fmt.Errorf("delivery: a forge message carries placement files, which no repository holds since ADR 0567: " +
 			"placement is the seat mesh-placement's state")
 	}
+	if err := f.checkPredefined(); err != nil {
+		return err
+	}
 	if err := checkRepository(f.Repository); err != nil {
 		return err
 	}