The assigner's integration test puts its responders' interest on the bus before it asks them (issue 1921, milestone 47/G, the group check of 616c42434ac2)

A manifest-reads ask the assigner made on manifest-reads-changed before the
test's SUB reached the server was answered by nobody and, by design, never
asked again; a flush is the barrier after each of the test's subscriptions.

Claude-Session: https://claude.ai/code/session_01NcbgfFSnn24M3GcqttoU7i

modules/mesh-delivery-assigner/cmd/mesh-delivery-assigner/integration_test.go

@@ -610,6 +610,10 @@ func TestWantsAreWrittenAndNoDifferenceIs(t *testing.T) {
 	}); err != nil {
 		t.Fatal(err)
 	}
+	// The responder's interest is on the bus before the event that asks it is said: the assigner asks a node once per
+	// manifest-reads-changed and never on a timer, so an ask that lands before this subscription reached the server is
+	// answered by nobody and is never asked again (the group check of 616c42434ac2 on a loaded build node).
+	subscribed(t, nc)
 	say := func(why string) {
 		body, _ := json.Marshal(nodeengine.ManifestReadsChangedEvent{V: 1, Node: "ace", ManifestReads: stated, At: time.Now().Format(time.RFC3339Nano), Why: why})
 		if _, err := b.js.Publish(b.ctx, enginereads.SubjectPrefix+"ace", body); err != nil {
@@ -677,6 +681,16 @@ func TestWantsAreWrittenAndNoDifferenceIs(t *testing.T) {
 	}
 }
 
+// subscribed returns once the server holds every subscription nc made: nats.go sends a SUB from its flusher, after
+// Subscribe has returned, so a responder or listener the test makes is not yet heard by a call or event another
+// connection sends at once. A flush's round trip is the barrier; no sleep stands in for it.
+func subscribed(t *testing.T, nc *nats.Conn) {
+	t.Helper()
+	if err := nc.Flush(); err != nil {
+		t.Fatalf("the test's subscriptions did not reach the bus: %v", err)
+	}
+}
+
 // bedState is one of the bed's buckets as the engine reads' tool reads it.
 type bedState struct {
 	b      *bed
@@ -1166,6 +1180,7 @@ func TestAProposalIsAnsweredApprovedAndWritten(t *testing.T) {
 	}); err != nil {
 		t.Fatal(err)
 	}
+	subscribed(t, nc)
 	for _, node := range []string{"anchor", "laptop"} {
 		rec, _ := nodeengineclient.EncodeHaveNode(nodeengine.HaveByNodeNodeValue{Record: &nodeengine.NodeRecord{Node: node}})
 		b.putJSON(t, buckets.Have, node+".node", rec)
@@ -1514,6 +1529,7 @@ func serveIndexer(t *testing.T, b *bed, nc *nats.Conn) {
 		if err != nil {
 			t.Fatal(err)
 		}
+		subscribed(t, nc)
 		t.Cleanup(func() { _ = sub.Unsubscribe() })
 	}
 }
@@ -1612,6 +1628,7 @@ func firstViewsBeforeAnyNewFormState(t *testing.T, b *bed, granted map[string][]
 	if err != nil {
 		t.Fatal(err)
 	}
+	subscribed(t, nc)
 	t.Cleanup(func() { _ = sub.Unsubscribe() })
 	ask := func(user, tool string) (views.Answer, error) {
 		return views.AskVia(func(key string, body any) (json.RawMessage, error) {