implemented dual Nextcloud push registration with separate general and talk apptypes to ensure reliable Talk notification delivery; introduced stacked MessagingStyle notifications for chat threads with support for circular conversation avatars and disk caching

lib/notification/notification_tasks.dart

@@ -6,6 +6,7 @@ import 'package:flutter/services.dart';
 import 'package:flutter_app_badge/flutter_app_badge.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
 
+import '../push/chat_thread_store.dart';
 import '../routing/app_routes.dart';
 import '../state/app/modules/chat_list/bloc/chat_list_bloc.dart';
 import 'notification_service.dart';
@@ -25,9 +26,9 @@ 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';
+  /// Per-chat tag scheme — canonical definition lives beside the stacked
+  /// notification id in chat_thread_store.dart.
+  static String chatTag(String chatToken) => chatNotificationTag(chatToken);
 
   /// Removes tray notifications belonging to [chatToken]. Eraser handles
   /// iOS (where the plugin's `getActiveNotifications` returns null ids
@@ -54,6 +55,13 @@ class NotificationTasks {
     } on Object catch (e) {
       log('Active-notification sweep failed: $e');
     }
+    // Drop the stacked-notification history too — otherwise the next push
+    // would resurrect all already-read messages in the new notification.
+    try {
+      await ChatThreadStore().clearChat(chatToken);
+    } on Object catch (e) {
+      log('Chat thread cleanup failed: $e');
+    }
   }
 
   /// Refreshes the chat list. Deliberately does NOT touch [ChatBloc] —