fix: sync topic sequence after server data

server/topic_test.go

@@ -1866,6 +1866,45 @@ func TestHandleBroadcastPresMe(t *testing.T) {
 	}
 }
 
+func TestHandleServerDataAdvancesLastID(t *testing.T) {
+	topicName := "p2pZAAAAAAAAABAAAAAAAAAAA"
+	helper := TopicTestHelper{}
+	helper.setUp(t, 2, types.TopicCatP2P, topicName, true)
+	defer helper.tearDown()
+
+	timestamp := time.Now().UTC().Round(time.Millisecond)
+	helper.topic.handleServerMsg(&ServerComMessage{
+		TenantID:          types.TenantID(1),
+		RcptTo:            topicName,
+		PreserveTopicName: true,
+		Data: &MsgServerData{
+			Topic:     topicName,
+			From:      types.ZeroUid.UserId(),
+			Timestamp: timestamp,
+			SeqId:     1,
+			Head:      map[string]any{"x-im-type": "system_notice"},
+			Content:   map[string]any{"text": "你们已成为好友，现在可以开始聊天了。"},
+		},
+	})
+	helper.finish()
+
+	if helper.topic.lastID != 1 {
+		t.Fatalf("Topic.lastID: expected server data to advance to 1, got %d", helper.topic.lastID)
+	}
+	if !helper.topic.touched.Equal(timestamp) {
+		t.Fatalf("Topic.touched: expected %s, got %s", timestamp, helper.topic.touched)
+	}
+	for i, result := range helper.results {
+		if len(result.messages) != 1 {
+			t.Fatalf("session %d expected one server data message, got %d", i, len(result.messages))
+		}
+		msg := result.messages[0].(*ServerComMessage)
+		if msg.Data == nil || msg.Data.SeqId != 1 {
+			t.Fatalf("session %d received unexpected message: %#v", i, msg)
+		}
+	}
+}
+
 func TestHandleBroadcastPresInactiveTopic(t *testing.T) {
 	topicName := "usrMe"
 	numUsers := 1