perf: batch group unread fanout

server/realtime_dispatcher_test.go

@@ -109,6 +109,60 @@ func TestRealtimeUserPresenceSkipsSessionsAttachedToTopic(t *testing.T) {
 	}
 }
 
+func TestRealtimeGroupUnreadBatchPreservesDetachedMultiDeviceNotification(t *testing.T) {
+	oldStore := globals.sessionStore
+	defer func() { globals.sessionStore = oldStore }()
+
+	tenantID := types.TenantID(1)
+	recipient := types.Uid(1002)
+	other := types.Uid(1003)
+	topic := "grpUnreadBatchTest"
+	globals.sessionStore = realtimeTestSessionStore(
+		realtimeTestSession("sid-attached", tenantID, recipient, topic),
+		realtimeTestSession("sid-detached-1", tenantID, recipient, ""),
+		realtimeTestSession("sid-detached-2", tenantID, recipient, ""),
+		realtimeTestSession("sid-other", tenantID, other, ""),
+	)
+	payload := realtimeGroupUnreadMessage{
+		Topic: topic,
+		Actor: types.Uid(1001).UserId(),
+		SeqID: 51,
+		Recipients: []realtimeGroupUnreadRecipient{
+			{User: recipient.UserId(), Source: topic},
+		},
+	}
+	raw, err := json.Marshal(payload)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	deliverRealtimeFanoutEnvelope(&store.RealtimeFanoutEnvelope{
+		TenantID:   tenantID,
+		Kind:       realtimeKindGroupUnread,
+		TargetType: realtimeTargetUsers,
+		Target:     topic,
+		Message:    raw,
+	})
+
+	if len(globals.sessionStore.Get("sid-attached").send) != 0 {
+		t.Fatal("attached session must rely on the topic data broadcast")
+	}
+	for _, sid := range []string{"sid-detached-1", "sid-detached-2"} {
+		select {
+		case got := <-globals.sessionStore.Get(sid).send:
+			pres := got.(*ServerComMessage).Pres
+			if pres == nil || pres.What != "msg" || pres.Src != topic || pres.SeqId != 51 || pres.SkipTopic != topic {
+				t.Fatalf("%s got unexpected presence: %#v", sid, pres)
+			}
+		default:
+			t.Fatalf("detached session %s must receive unread presence", sid)
+		}
+	}
+	if len(globals.sessionStore.Get("sid-other").send) != 0 {
+		t.Fatal("non-recipient session received unread presence")
+	}
+}
+
 func TestRealtimeP2PTopicFallbackRewritesVisibleTopic(t *testing.T) {
 	oldStore := globals.sessionStore
 	oldHub := globals.hub