diff --git a/apps/lib/core/notifications/local_notification_service.dart b/apps/lib/core/notifications/local_notification_service.dart
index 2a9de1e..4821ea1 100644
--- a/apps/lib/core/notifications/local_notification_service.dart
+++ b/apps/lib/core/notifications/local_notification_service.dart
@@ -1,8 +1,6 @@
-import 'dart:async';
 import 'dart:convert';
 
 import 'package:flutter/foundation.dart';
-import 'package:flutter/widgets.dart';
 import 'package:flutter_local_notifications/flutter_local_notifications.dart';
 import 'package:shared_preferences/shared_preferences.dart';
 import 'package:timezone/data/latest.dart' as tz_data;
@@ -21,17 +19,6 @@ typedef ReminderNotificationActionHandler =
       required ReminderPayload payload,
     });
 
-typedef ReminderPermissionFallbackTracker =
-    void Function({
-      required String actionExecutionId,
-      required String permissionState,
-      required String appLifecycleState,
-      required String platform,
-    });
-
-typedef ReminderInAppReminderHandler =
-    Future<void> Function(ReminderPayload payload);
-
 class LocalNotificationService {
   static const String _iosCategoryId = 'calendar_reminder_v2';
   static const String _actionCancel = 'cancel';
@@ -39,33 +26,22 @@ class LocalNotificationService {
 
   final FlutterLocalNotificationsPlugin _plugin;
   final ReminderOverlapPolicy _overlapPolicy;
-  final ReminderPermissionFallbackTracker? _permissionFallbackTracker;
   ReminderActionDedupeStore? _dedupeStore;
   bool _initialized = false;
-  bool _canDeliverSystemNotification = true;
   ReminderNotificationActionHandler? _actionHandler;
-  ReminderInAppReminderHandler? _inAppReminderHandler;
-  final Map<String, List<Timer>> _inAppFallbackTimersByEventId =
-      <String, List<Timer>>{};
 
   LocalNotificationService({
     FlutterLocalNotificationsPlugin? plugin,
     ReminderOverlapPolicy? overlapPolicy,
     ReminderActionDedupeStore? dedupeStore,
-    ReminderPermissionFallbackTracker? permissionFallbackTracker,
   }) : _plugin = plugin ?? FlutterLocalNotificationsPlugin(),
        _overlapPolicy = overlapPolicy ?? const ReminderOverlapPolicy(),
-       _dedupeStore = dedupeStore,
-       _permissionFallbackTracker = permissionFallbackTracker;
+       _dedupeStore = dedupeStore;
 
   void bindActionHandler(ReminderNotificationActionHandler handler) {
     _actionHandler = handler;
   }
 
-  void bindInAppReminderHandler(ReminderInAppReminderHandler handler) {
-    _inAppReminderHandler = handler;
-  }
-
   Future<void> initialize() async {
     if (_initialized) {
       return;
@@ -107,18 +83,7 @@ class LocalNotificationService {
         .resolvePlatformSpecificImplementation<
           AndroidFlutterLocalNotificationsPlugin
         >();
-    final androidPermissionGranted = await androidImpl
-        ?.requestNotificationsPermission();
-    if (defaultTargetPlatform == TargetPlatform.android &&
-        androidPermissionGranted == false) {
-      _canDeliverSystemNotification = false;
-      _permissionFallbackTracker?.call(
-        actionExecutionId: 'permission_check',
-        permissionState: 'denied',
-        appLifecycleState: 'unknown',
-        platform: 'android',
-      );
-    }
+    await androidImpl?.requestNotificationsPermission();
     await androidImpl?.requestExactAlarmsPermission();
     await androidImpl?.requestFullScreenIntentPermission();
 
@@ -141,24 +106,8 @@ class LocalNotificationService {
     _dedupeStore = ReminderActionDedupeStore(prefs);
   }
 
-  Future<void> _refreshAndroidNotificationAvailability() async {
-    if (defaultTargetPlatform != TargetPlatform.android) {
-      return;
-    }
-    final androidImpl = _plugin
-        .resolvePlatformSpecificImplementation<
-          AndroidFlutterLocalNotificationsPlugin
-        >();
-    final enabled = await androidImpl?.areNotificationsEnabled();
-    if (enabled == null) {
-      return;
-    }
-    _canDeliverSystemNotification = enabled;
-  }
-
   Future<void> upsertEventReminder(ScheduleItemModel event) async {
     await initialize();
-    await _refreshAndroidNotificationAvailability();
     if (event.status != ScheduleStatus.active ||
         event.metadata?.reminderMinutes == null) {
       await cancelEventReminder(event.id);
@@ -172,14 +121,6 @@ class LocalNotificationService {
       return;
     }
 
-    if (!_canDeliverSystemNotification) {
-      await _scheduleInAppFallbackRemindersFrom(
-        event: event,
-        firstFireAt: fireAt,
-      );
-      return;
-    }
-
     await cancelEventReminder(event.id);
     await _scheduleRemindersFrom(event: event, firstFireAt: fireAt);
   }
@@ -189,21 +130,12 @@ class LocalNotificationService {
     DateTime fireAt,
   ) async {
     await initialize();
-    await _refreshAndroidNotificationAvailability();
-    if (!_canDeliverSystemNotification) {
-      await _scheduleInAppFallbackRemindersFrom(
-        event: event,
-        firstFireAt: fireAt,
-      );
-      return;
-    }
     await cancelEventReminder(event.id);
     await _scheduleRemindersFrom(event: event, firstFireAt: fireAt);
   }
 
   Future<void> cancelEventReminder(String eventId) async {
     await initialize();
-    _cancelInAppFallbackTimers(eventId);
 
     final pending = await _plugin.pendingNotificationRequests();
     for (final request in pending) {
@@ -224,23 +156,6 @@ class LocalNotificationService {
     Iterable<ScheduleItemModel> events,
   ) async {
     await initialize();
-    await _refreshAndroidNotificationAvailability();
-    if (!_canDeliverSystemNotification) {
-      _clearAllInAppFallbackTimers();
-      final now = DateTime.now();
-      final groups = _overlapPolicy.groupByMinute(events, now: now);
-      for (final group in groups) {
-        if (group.isAggregate) {
-          await _scheduleInAppAggregateFallback(group.events, group.fireAt);
-          continue;
-        }
-        await _scheduleInAppFallbackRemindersFrom(
-          event: group.events.first,
-          firstFireAt: group.fireAt,
-        );
-      }
-      return;
-    }
 
     final now = DateTime.now();
     final groups = _overlapPolicy.groupByMinute(events, now: now);
@@ -288,7 +203,7 @@ class LocalNotificationService {
         : AndroidScheduleMode.inexactAllowWhileIdle;
   }
 
-  NotificationDetails _buildNotificationDetails() {
+  NotificationDetails _buildNotificationDetails(DateTime fireAt) {
     return NotificationDetails(
       android: AndroidNotificationDetails(
         'calendar_alarm_channel_v2',
@@ -304,6 +219,7 @@ class LocalNotificationService {
         vibrationPattern: Int64List.fromList([0, 1000, 500, 1200]),
         timeoutAfter: 30000,
         autoCancel: true,
+        groupKey: _getGroupKey(fireAt),
         actions: <AndroidNotificationAction>[
           AndroidNotificationAction(_actionCancel, '取消'),
           AndroidNotificationAction(
@@ -313,15 +229,30 @@ class LocalNotificationService {
           ),
         ],
       ),
-      iOS: const DarwinNotificationDetails(
+      iOS: DarwinNotificationDetails(
         presentAlert: true,
         presentSound: true,
         presentBadge: true,
         categoryIdentifier: _iosCategoryId,
+        threadIdentifier: _getThreadIdentifier(fireAt),
       ),
     );
   }
 
+  String _getThreadIdentifier(DateTime fireAt) {
+    final bucket =
+        fireAt.millisecondsSinceEpoch ~/
+        const Duration(minutes: 1).inMilliseconds;
+    return 'calendar_reminder_$bucket';
+  }
+
+  String _getGroupKey(DateTime fireAt) {
+    final bucket =
+        fireAt.millisecondsSinceEpoch ~/
+        const Duration(minutes: 1).inMilliseconds;
+    return 'com.socialapp.calendar.$bucket';
+  }
+
   Future<void> _scheduleSingleReminder({
     required ScheduleItemModel event,
     required DateTime fireAt,
@@ -347,7 +278,7 @@ class LocalNotificationService {
       version: 1,
     );
 
-    final details = _buildNotificationDetails();
+    final details = _buildNotificationDetails(fireAt);
     final scheduledAt = tz.TZDateTime.from(fireAt, tz.local);
     final mode = await _resolveAndroidScheduleMode();
 
@@ -378,185 +309,6 @@ class LocalNotificationService {
     }
   }
 
-  Future<void> _scheduleInAppAggregateFallback(
-    List<ScheduleItemModel> events,
-    DateTime fireAt,
-  ) async {
-    if (events.isEmpty) {
-      return;
-    }
-
-    final aggregateIds = events.map((event) => event.id).toList();
-    for (final eventId in aggregateIds) {
-      _cancelInAppFallbackTimers(eventId);
-    }
-
-    final first = events.first;
-    final payload = ReminderPayload(
-      eventId: first.id,
-      title: '你有${events.length}个日程提醒',
-      startAt: first.startAt,
-      endAt: first.endAt,
-      timezone: first.timezone,
-      mode: ReminderPayloadMode.aggregate,
-      aggregateIds: aggregateIds,
-      fireTimeBucket:
-          fireAt.millisecondsSinceEpoch ~/
-          const Duration(minutes: 1).inMilliseconds,
-      version: 1,
-    );
-    await _scheduleInAppFallbackPayload(
-      eventId: first.id,
-      fireAt: fireAt,
-      payload: payload,
-      relatedEventIds: aggregateIds,
-    );
-  }
-
-  Future<void> _scheduleInAppFallbackRemindersFrom({
-    required ScheduleItemModel event,
-    required DateTime firstFireAt,
-  }) async {
-    _cancelInAppFallbackTimers(event.id);
-
-    final endAt = event.endAt;
-    var cursor = firstFireAt;
-    Future<void> scheduleAt(DateTime fireAt) async {
-      final payload = ReminderPayload(
-        eventId: event.id,
-        title: event.title,
-        startAt: event.startAt,
-        endAt: event.endAt,
-        timezone: event.timezone,
-        location: event.metadata?.location,
-        notes: event.metadata?.notes,
-        color: event.metadata?.color,
-        mode: ReminderPayloadMode.single,
-        fireTimeBucket:
-            fireAt.millisecondsSinceEpoch ~/
-            const Duration(minutes: 1).inMilliseconds,
-        version: 1,
-      );
-      await _scheduleInAppFallbackPayload(
-        eventId: event.id,
-        fireAt: fireAt,
-        payload: payload,
-        relatedEventIds: <String>[event.id],
-      );
-    }
-
-    if (endAt == null) {
-      await scheduleAt(cursor);
-      return;
-    }
-
-    while (cursor.isBefore(endAt)) {
-      await scheduleAt(cursor);
-      cursor = cursor.add(const Duration(minutes: 10));
-    }
-  }
-
-  Future<Timer?> _scheduleInAppFallbackPayload({
-    required String eventId,
-    required DateTime fireAt,
-    required ReminderPayload payload,
-    required List<String> relatedEventIds,
-  }) async {
-    final handler = _inAppReminderHandler;
-    final bucket =
-        fireAt.millisecondsSinceEpoch ~/
-        const Duration(minutes: 1).inMilliseconds;
-    final actionExecutionId = '$eventId|fallback|$bucket';
-    _trackFallback(
-      actionExecutionId: actionExecutionId,
-      permissionState: 'denied',
-    );
-
-    if (handler == null) {
-      return null;
-    }
-
-    final now = DateTime.now();
-    final delay = fireAt.isAfter(now) ? fireAt.difference(now) : Duration.zero;
-    late final Timer timer;
-    timer = Timer(delay, () {
-      final activeHandler = _inAppReminderHandler;
-      if (activeHandler == null) {
-        _unregisterInAppFallbackTimer(relatedEventIds, timer);
-        return;
-      }
-      activeHandler(payload);
-      _unregisterInAppFallbackTimer(relatedEventIds, timer);
-    });
-    _registerInAppFallbackTimer(relatedEventIds, timer);
-    return timer;
-  }
-
-  void _registerInAppFallbackTimer(List<String> eventIds, Timer timer) {
-    for (final eventId in eventIds) {
-      final timers = _inAppFallbackTimersByEventId.putIfAbsent(
-        eventId,
-        () => <Timer>[],
-      );
-      timers.add(timer);
-    }
-  }
-
-  void _unregisterInAppFallbackTimer(List<String> eventIds, Timer timer) {
-    for (final eventId in eventIds) {
-      final timers = _inAppFallbackTimersByEventId[eventId];
-      if (timers == null) {
-        continue;
-      }
-      timers.remove(timer);
-      if (timers.isEmpty) {
-        _inAppFallbackTimersByEventId.remove(eventId);
-      }
-    }
-  }
-
-  void _cancelInAppFallbackTimers(String eventId) {
-    final timers = _inAppFallbackTimersByEventId.remove(eventId);
-    if (timers == null) {
-      return;
-    }
-
-    for (final timer in timers.toSet()) {
-      for (final entry in _inAppFallbackTimersByEventId.entries) {
-        entry.value.remove(timer);
-      }
-      timer.cancel();
-    }
-
-    _inAppFallbackTimersByEventId.removeWhere((_, value) => value.isEmpty);
-  }
-
-  void _clearAllInAppFallbackTimers() {
-    final allTimers = <Timer>{};
-    for (final timers in _inAppFallbackTimersByEventId.values) {
-      allTimers.addAll(timers);
-    }
-    _inAppFallbackTimersByEventId.clear();
-
-    for (final timer in allTimers) {
-      timer.cancel();
-    }
-  }
-
-  void _trackFallback({
-    required String actionExecutionId,
-    required String permissionState,
-  }) {
-    final lifecycleState =
-        WidgetsBinding.instance.lifecycleState?.name ?? 'unknown';
-    _permissionFallbackTracker?.call(
-      actionExecutionId: actionExecutionId,
-      permissionState: permissionState,
-      appLifecycleState: lifecycleState,
-      platform: 'android',
-    );
-  }
-
   Future<void> _scheduleRemindersFrom({
     required ScheduleItemModel event,
     required DateTime firstFireAt,
@@ -602,7 +354,7 @@ class LocalNotificationService {
       version: 1,
     );
 
-    final details = _buildNotificationDetails();
+    final details = _buildNotificationDetails(fireAt);
     final scheduledAt = tz.TZDateTime.from(fireAt, tz.local);
     final mode = await _resolveAndroidScheduleMode();
     final preview = events.take(3).map((item) => item.title).join('、');
@@ -678,13 +430,6 @@ class LocalNotificationService {
     }
 
     if (action == null) {
-      if (response.notificationResponseType ==
-          NotificationResponseType.selectedNotification) {
-        final presenter = _inAppReminderHandler;
-        if (presenter != null) {
-          await presenter(payload);
-        }
-      }
       return;
     }