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

lib/notification/notification_tasks.dart

@@ -1,11 +1,15 @@
+import 'dart:developer';
+
+import 'package:eraser/eraser.dart';
 import 'package:firebase_messaging/firebase_messaging.dart';
 import 'package:flutter/cupertino.dart';
+import 'package:flutter/services.dart';
 import 'package:flutter_app_badge/flutter_app_badge.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
 
 import '../routing/app_routes.dart';
-import '../state/app/modules/chat/bloc/chat_bloc.dart';
 import '../state/app/modules/chat_list/bloc/chat_list_bloc.dart';
+import 'notification_service.dart';
 
 class NotificationTasks {
   static void updateBadgeCount(RemoteMessage notification) {
@@ -14,9 +18,43 @@ class NotificationTasks {
     );
   }
 
+  /// Per-chat tag scheme. MUST match the Notify backend, which sets this
+  /// value on `AndroidNotification.setTag` AND `apns-collapse-id`.
+  static String chatTag(String chatToken) => 'talk_$chatToken';
+
+  /// Removes tray notifications belonging to [chatToken]. Eraser handles
+  /// iOS (where the plugin's `getActiveNotifications` returns null ids
+  /// for FCM posts and can't cancel them); the local-notifications sweep
+  /// handles Android and acts as a fallback while Eraser's native side
+  /// isn't built in yet.
+  static Future<void> clearNotificationsForChat(String chatToken) async {
+    final tag = chatTag(chatToken);
+    try {
+      await Eraser.clearAppNotificationsByTag(tag);
+    } on MissingPluginException {
+      // Eraser native code not yet linked — needs flutter clean + run.
+    } on Object catch (e) {
+      log('Eraser($tag) failed: $e');
+    }
+    try {
+      final plugin = NotificationService().flutterLocalNotificationsPlugin;
+      final actives = await plugin.getActiveNotifications();
+      for (final n in actives) {
+        final id = n.id;
+        if (id == null) continue;
+        if (n.tag == tag) await plugin.cancel(id: id, tag: n.tag);
+      }
+    } on Object catch (e) {
+      log('Active-notification sweep failed: $e');
+    }
+  }
+
+  /// Refreshes the chat list. Deliberately does NOT touch [ChatBloc] —
+  /// the open chat view manages its own state via long-poll, and refreshing
+  /// it here would re-fetch the last-opened chat with setReadMarker=on
+  /// even if the user has already left.
   static void updateProviders(BuildContext context) {
     context.read<ChatListBloc>().refresh();
-    context.read<ChatBloc>().refresh();
   }
 
   /// Switches to the Talk tab. If [chatToken] is provided, also schedules