implemented chat long-polling and optimistic updates, centralized notification management, optimized avatar caching

lib/state/app/modules/chat_list/bloc/chat_list_bloc.dart

@@ -1,8 +1,10 @@
+import 'dart:async';
 import 'dart:developer';
 
 import 'package:flutter_app_badge/flutter_app_badge.dart';
 
 import '../../../../../api/errors/error_mapper.dart';
+import '../../../../../api/marianumcloud/talk/chat/get_chat_response.dart';
 import '../../../../../api/marianumcloud/talk/room/get_room_response.dart';
 import '../../../infrastructure/loadable_state/loading_error.dart';
 import '../../../infrastructure/utility_widgets/loadable_hydrated_bloc/loadable_hydrated_bloc.dart';
@@ -15,6 +17,8 @@ class ChatListBloc
     extends
         LoadableHydratedBloc<ChatListEvent, ChatListState, ChatListRepository> {
   bool _forceRenew = false;
+  Timer? _autoRefreshTimer;
+  Duration? _autoRefreshInterval;
 
   @override
   void retry() {
@@ -22,6 +26,27 @@ class ChatListBloc
     super.retry();
   }
 
+  @override
+  Future<void> close() {
+    _autoRefreshTimer?.cancel();
+    return super.close();
+  }
+
+  /// Sets (or clears) the recurring background refresh. Silent so the
+  /// loading bar doesn't blink several times a minute; pull-to-refresh
+  /// and tab-activation refreshes are non-silent for explicit feedback.
+  void setAutoRefreshInterval(Duration? interval) {
+    if (interval == _autoRefreshInterval) return;
+    _autoRefreshInterval = interval;
+    _autoRefreshTimer?.cancel();
+    _autoRefreshTimer = null;
+    if (interval == null) return;
+    _autoRefreshTimer = Timer.periodic(interval, (_) {
+      if (isClosed) return;
+      refresh(silent: true);
+    });
+  }
+
   @override
   ChatListRepository repository() => ChatListRepository();
 
@@ -51,8 +76,8 @@ class ChatListBloc
     if (capturedError != null) throw capturedError!;
   }
 
-  Future<void> refresh({bool renew = true}) async {
-    add(RefetchStarted<ChatListState>());
+  Future<void> refresh({bool renew = true, bool silent = false}) async {
+    if (!silent) add(RefetchStarted<ChatListState>());
     Object? capturedError;
     try {
       final rooms = await repo.data.getRooms(
@@ -82,6 +107,64 @@ class ChatListBloc
     await refresh();
   }
 
+  /// Optimistically clears the unread counter for [token] so the tile
+  /// reacts before a refresh roundtrip lands. Server-side mark-as-read
+  /// is the caller's job (see [ChatBloc.sendServerReadMarker]).
+  void markRoomAsRead(String token, int lastMessageId) {
+    _mutateRoom(token, (r) {
+      if (r.unreadMessages == 0 && r.lastReadMessage >= lastMessageId) {
+        return false;
+      }
+      r.unreadMessages = 0;
+      r.unreadMention = false;
+      r.unreadMentionDirect = false;
+      if (lastMessageId > r.lastReadMessage) r.lastReadMessage = lastMessageId;
+      return true;
+    });
+  }
+
+  /// Pushes a freshly-received message into the matching room tile so the
+  /// list shows the right preview text + activity timestamp before the
+  /// next full refresh lands. Also clears unread because the long-poll
+  /// only feeds this in for an actively-open chat.
+  void applyIncomingMessage(String token, GetChatResponseObject message) {
+    _mutateRoom(token, (r) {
+      final wasRead =
+          r.unreadMessages == 0 && r.lastReadMessage >= message.id;
+      final hasNewer = r.lastMessage.id >= message.id;
+      if (wasRead && hasNewer) return false;
+      r.unreadMessages = 0;
+      r.unreadMention = false;
+      r.unreadMentionDirect = false;
+      if (message.id > r.lastReadMessage) r.lastReadMessage = message.id;
+      if (message.id > r.lastMessage.id) r.lastMessage = message;
+      if (message.timestamp > r.lastActivity) r.lastActivity = message.timestamp;
+      return true;
+    });
+  }
+
+  /// Mutates the room with [token] in-place via [mutator] (returning
+  /// true if anything changed) and re-emits if so. Builds a fresh
+  /// [GetRoomResponse] so equality-by-identity in the bloc state
+  /// recognises the change and rebuilds.
+  void _mutateRoom(
+    String token,
+    bool Function(GetRoomResponseObject room) mutator,
+  ) {
+    final rooms = innerState?.rooms;
+    if (rooms == null) return;
+    var changed = false;
+    final updated = rooms.data.map((r) {
+      if (r.token != token) return r;
+      if (mutator(r)) changed = true;
+      return r;
+    }).toSet();
+    if (!changed) return;
+    final newRooms = GetRoomResponse(updated)..headers = rooms.headers;
+    add(Emit((s) => s.copyWith(rooms: newRooms)));
+    _updateAppBadge(newRooms);
+  }
+
   void _updateAppBadge(GetRoomResponse rooms) {
     try {
       final unread = rooms.data.fold<int>(