The gate's module check notes a seat another module declares, which it was not given (hq issue 364)

The gate passes only the manifests a change touches, so a module that starts using the operator channel
was refused for a declaration it could not see. Over every manifest it stays a refusal.

cmd/mesh-controller/check_test.go

@@ -103,3 +103,23 @@ func TestTheControllersManifestServesEveryVerbOfItsSeat(t *testing.T) {
 		t.Fatalf("the controller's own module.json fails module check: %v\n%s", err, out.String())
 	}
 }
+
+// A module that uses a seat another module declares (novox/hq issue 364): refused over the whole catalogue when the
+// declarer is missing, a note when the gate says it gives only the manifests a change touches.
+func TestASeatAnotherModuleDeclaresIsANoteOverSomeManifests(t *testing.T) {
+	dir := t.TempDir()
+	user := filepath.Join(dir, "user.json")
+	os.WriteFile(user, []byte(`{"module":"asker","version":"1","uses":["operator-channel"]}`), 0o600)
+	var out bytes.Buffer
+	if err := moduleCheck([]string{user}, &out); err == nil {
+		t.Fatalf("a use of a seat nothing given declares passed the whole-catalogue check:\n%s", out.String())
+	}
+	t.Setenv(SomeManifestsVar, "1")
+	out.Reset()
+	if err := moduleCheck([]string{user}, &out); err != nil {
+		t.Fatalf("over some manifests the use was refused:\n%s", out.String())
+	}
+	if !strings.Contains(out.String(), "note: asker uses the seat \"operator-channel\"") {
+		t.Fatalf("the note was not said:\n%s", out.String())
+	}
+}