TW-2834 Fix missing messages when open chat room by notification

Author: tddang-linagora

docs/adr/0034-fix-notification-redirection-race-condition.md

@@ -0,0 +1,64 @@
+# 34. Fix Notification Redirection Race Condition
+
+Date: 2026-01-15
+
+## Status
+
+Accepted
+
+## Context
+
+Users reported that when clicking a notification to navigate to a room, sometimes the messages would fail to load, and the "load more" function would not trigger.
+Investigation revealed a race condition in `ChatController`:
+
+- The timeline loading logic (`_tryLoadTimeline`) was called in `initState` but used the `room` variable.
+- The `room` variable was previously initialized in the `build` method of `ChatView`.
+- When navigating via deep link or notification, the build method might not have run before `initState` tried to access `room`, leading to initialization with a null or stale room, or simply failing to load the correct timeline for the context event.
+
+Additionally, when switching between rooms via notifications (e.g., being in Room A and clicking a notification for Room B), the `ChatController` did not cleanly detect the change and re-initialize the timeline, leading to mixed state.
+
+## Decision
+
+We decided to move the room initialization logic to the earliest possible point in the `ChatController` lifecycle and explicitly handle room updates.
+
+### 1. Early Room Initialization
+
+Moved `room` initialization from `ChatView.build` to `ChatController.initState`.
+
+- A new method `_initRoom()` was created to initialize `matrix` client and `room`.
+- `_initRoom()` is called at the beginning of `initState`.
+
+### 2. Explicit Update Handling
+
+Updated `didUpdateWidget` in `ChatController`:
+
+- Checks if `widget.roomId` has changed compared to `oldWidget.roomId`.
+- If changed, it performs a full room state reset and re-initialization:
+  - Unsubscribes existing room event listeners (canceling any active timers or streams).
+  - Clears and re-fetches pinned events.
+  - Resets cached presence and participants data.
+  - Calls `_initRoom()` to switch the internal matrix room reference.
+  - Re-subscribes to room listeners for the new room.
+  - Calls `_tryLoadTimeline()` to load the initial messages for the new room.
+- This ensures all room-scoped resources are fully refreshed and correctly isolated on room switch.
+
+### 3. Removal of Side-Effects from Build
+
+Removed the assignment of `controller.room` inside `ChatView.build`. The build method now strictly reads from the controller and returns early if `room` is null (though `initState` protections make this unlikely to happen in a visible way).
+
+## Consequences
+
+### Positive
+
+- **Reliability:** Notifications and deep links now reliably load the correct room and timeline.
+- **Correctness:** Timeline loading (`_tryLoadTimeline`) now is guaranteed to have a valid `room` instance.
+- **Maintainability:** `ChatView.build` is purer and has fewer side effects. State initialization is where it belongs, in `initState`.
+
+### Negative
+
+- **Boilerplate:** We have to manually handle `didUpdateWidget` to detect changes that `build` would have picked up automatically (though incorrectly for this use case).
+
+### Files Modified
+
+1. `lib/pages/chat/chat.dart` - `initState`, `_initRoom`, `didUpdateWidget`.
+2. `lib/pages/chat/chat_view.dart` - Removed initialization logic from `build`.

lib/pages/chat/chat.dart

@@ -622,7 +622,12 @@ class ChatController extends State<Chat>
     scrollToEventId(fullyRead, highlight: false);
   }
 
-  void _tryLoadTimeline() async {
+  Future<void> _tryLoadTimeline() async {
+    final currentRoomId = roomId;
+    if (room == null && currentRoomId != null) {
+      room = matrix?.client.getRoomById(currentRoomId);
+    }
+
     _updateOpeningChatViewStateNotifier(ViewEventListLoading());
     loadTimelineFuture = _getTimeline();
     try {
@@ -649,6 +654,8 @@ class ChatController extends State<Chat>
           scrollToEventIdAndHighlight(eventId);
         }
       });
+      if (!mounted || roomId != currentRoomId) return;
+
       await _tryRequestHistory();
       final fullyRead = room?.fullyRead;
       if (fullyRead == null || fullyRead.isEmpty || fullyRead == '') {
@@ -657,7 +664,6 @@ class ChatController extends State<Chat>
       if (room?.hasNewMessages == true) {
         _initUnreadLocation(fullyRead);
       }
-      if (!mounted) return;
     } catch (e, s) {
       Logs().e('Failed to load timeline', e, s);
       rethrow;
@@ -1225,8 +1231,12 @@ class ChatController extends State<Chat>
   }
 
   Future<void> _getTimeline({String? eventContextId}) async {
+    final currentRoomId = roomId;
     await Matrix.of(context).client.roomsLoading;
     await Matrix.of(context).client.accountDataLoading;
+
+    if (!mounted || roomId != currentRoomId) return;
+
     if (eventContextId != null &&
         (!eventContextId.isValidMatrixId || eventContextId.sigil != '\$')) {
       eventContextId = null;
@@ -1241,12 +1251,14 @@ class ChatController extends State<Chat>
       );
     } catch (e, s) {
       Logs().w('Unable to load timeline on event ID $eventContextId', e, s);
-      if (!mounted) return;
+      if (!mounted || roomId != currentRoomId) return;
       timeline = await room?.getTimeline(onUpdate: updateView);
-      if (!mounted) return;
+      if (!mounted || roomId != currentRoomId) return;
     }
     timeline?.requestKeys(onlineKeyBackupOnly: false);
-    if (room!.markedUnread) room?.markUnread(false);
+
+    // Safely check room state
+    if (room?.markedUnread == true) room?.markUnread(false);
 
     return;
   }
@@ -2968,9 +2980,37 @@ class ChatController extends State<Chat>
     EventTypes.Sticker,
   ];
 
+  void _resetState() {
+    // Cancel any pending operations or subscriptions for the old room
+    onUpdateEventStreamSubcription?.cancel();
+    cachedPresenceStreamSubscription?.cancel();
+    _jumpToEventIdSubscription?.cancel();
+    ignoredUsersStreamSub?.cancel();
+    _timestampTimer?.cancel();
+
+    // Clear notifiers that might hold old room state
+    replyEventNotifier.value = null;
+    editEventNotifier.value = null;
+    stickyTimestampNotifier.value = null;
+    selectedEvents.clear();
+    pinnedEventsController.reset();
+
+    // Reset timeline and futures
+    timeline?.cancelSubscriptions();
+    timeline = null;
+    loadTimelineFuture = null;
+
+    // Reset other state variables
+    _pendingReadMarkerEventId = null;
+    _currentChatScrollState = ChatScrollState.endScroll;
+  }
+
   Future<void> _tryRequestHistory() async {
     if (timeline == null) return;
 
+    // Check mounted after async gap if any (none here but good practice)
+    if (!mounted) return;
+
     final allMembershipEvents = timeline!.events.every(
       (event) => event.type == EventTypes.RoomMember,
     );
@@ -2987,6 +3027,7 @@ class ChatController extends State<Chat>
         await requestHistory(historyCount: _defaultEventCountDisplay).then((
           response,
         ) async {
+          if (!mounted) return;
           Logs().v('Chat::_tryRequestHistory():: Try request history success');
           if (allMembershipEvents) {
             await requestHistory(
@@ -3001,7 +3042,9 @@ class ChatController extends State<Chat>
       } catch (e) {
         Logs().e('Chat::_tryRequestHistory():: Error - $e');
       } finally {
-        _updateOpeningChatViewStateNotifier(ViewEventListSuccess());
+        if (mounted) {
+          _updateOpeningChatViewStateNotifier(ViewEventListSuccess());
+        }
       }
     } else {
       _updateOpeningChatViewStateNotifier(ViewEventListSuccess());
@@ -3594,6 +3637,7 @@ class ChatController extends State<Chat>
   @override
   void initState() {
     super.initState();
+    _initRoom();
     _initializePinnedEvents();
     _listenOnJumpToEventFromSearch();
     registerPasteShortcutListeners();
@@ -3622,6 +3666,14 @@ class ChatController extends State<Chat>
     showEmojiPickerComposerNotifier.addListener(_emojiPickerListener);
   }
 
+  void _initRoom() {
+    // Only init if not already initialized or needed
+    matrix ??= Matrix.read(context);
+    final client = matrix!.client;
+    sendingClient = client;
+    room = client.getRoomById(roomId!);
+  }
+
   @override
   void didChangeDependencies() {
     super.didChangeDependencies();
@@ -3637,6 +3689,17 @@ class ChatController extends State<Chat>
     if (PlatformInfos.isMobile) {
       highlightEventId = GoRouterState.of(context).uri.queryParameters['event'];
     } else {
+      if (oldWidget.roomId != widget.roomId) {
+        _resetState();
+        _initRoom();
+        _tryLoadTimeline();
+        _initializePinnedEvents();
+        _listenRoomUpdateEvent();
+        // Re-initialize other room-specific items
+        initCachedPresence();
+        _requestParticipants();
+        listenIgnoredUser();
+      }
       final currentLocation = html.window.location.href;
       highlightEventId = Uri.tryParse(
         Uri.tryParse(currentLocation)?.fragment ?? '',

lib/pages/chat/chat_pinned_events/pinned_events_controller.dart

@@ -152,6 +152,12 @@ class PinnedEventsController {
     jumpToPinnedMessageCallback?.call(index);
   }
 
+  void reset() {
+    currentPinnedEventNotifier.value = null;
+    getPinnedMessageNotifier.value = Right(ChatGetPinnedEventsInitial());
+    _pinnedEventsSubscription?.cancel();
+  }
+
   void dispose() {
     currentPinnedEventNotifier.dispose();
     getPinnedMessageNotifier.dispose();

lib/pages/chat/chat_view.dart

@@ -7,7 +7,6 @@ import 'package:fluffychat/pages/chat/events/message_content_mixin.dart';
 import 'package:fluffychat/presentation/mixins/audio_mixin.dart';
 import 'package:fluffychat/resource/image_paths.dart';
 import 'package:fluffychat/utils/stream_extension.dart';
-import 'package:fluffychat/widgets/matrix.dart';
 import 'package:fluffychat/widgets/twake_components/twake_icon_button.dart';
 import 'package:flutter/material.dart';
 import 'package:fluffychat/generated/l10n/app_localizations.dart';
@@ -92,10 +91,6 @@ class ChatView extends StatelessWidget with MessageContentMixin {
 
   @override
   Widget build(BuildContext context) {
-    controller.matrix ??= Matrix.of(context);
-    final client = controller.matrix!.client;
-    controller.sendingClient ??= client;
-    controller.room = controller.sendingClient!.getRoomById(controller.roomId!);
     if (controller.room == null) {
       return const SizedBox.shrink();
     }