catalogue.InvokedVerbs reads a manifest's invokes in both forms for a part that holds no Manifest

Builds: design 47 G A-275, §558

Claude-Session: https://claude.ai/code/session_01NcbgfGKaxw984XyAPfLm4h

go/catalogue/login_shell_execute_test.go

@@ -76,3 +76,16 @@ func TestAHolderOfAMarkedVerbDeclaresItsApprovalsStateWithKeyTTL(t *testing.T) {
 		t.Errorf("a seat with no marked verb: approvals unserved is %v, want it named", got)
 	}
 }
+
+// Design 47 G A-275: InvokedVerbs reads both forms of an `invokes` entry and refuses one of neither.
+func TestInvokedVerbsReadsBothFormsAndRefusesAnother(t *testing.T) {
+	got, err := InvokedVerbs(json.RawMessage(`["seat:a.b",{"verb":"seat:c.d","fields":["x"]}]`))
+	if err != nil || len(got) != 2 || got[0] != "seat:a.b" || got[1] != "seat:c.d" {
+		t.Fatalf("%v, %v", got, err)
+	}
+	for _, bad := range []string{`[3]`, `{"verb":"x"}`, `[{"verb":""}]`} {
+		if _, err := InvokedVerbs(json.RawMessage(bad)); err == nil {
+			t.Errorf("%s was read", bad)
+		}
+	}
+}

go/catalogue/manifest.go

@@ -2265,3 +2265,17 @@ const InstancesInterchangeable = "interchangeable"
 // WhileStopped is the resource key naming the containers a scheduled step holds still while it
 // runs (novox/hq ADR 0189). Carried to the host unchanged, like `schedule`.
 const WhileStopped = "while-stopped"
+
+// InvokedVerbs is the verbs of a manifest's `invokes` in either form, a verb or {verb, fields} (design 47 G §558, A-275): the
+// one reader of the field for a part that holds no Manifest. An entry of neither form is an error, never none.
+func InvokedVerbs(raw json.RawMessage) ([]string, error) {
+	keys := map[string]json.RawMessage{"invokes": raw}
+	if _, err := readInvokes(keys); err != nil {
+		return nil, err
+	}
+	var verbs []string
+	if err := json.Unmarshal(keys["invokes"], &verbs); err != nil {
+		return nil, fmt.Errorf("invokes: a list of verbs, or of {verb, fields}: %w", err)
+	}
+	return verbs, nil
+}