fix(notification): harden local alerts

lib/core/services/notification_service.dart

@@ -117,11 +117,15 @@ class NotificationService {
       enableVibration: true,
     );
 
-    await _notifications
-        .resolvePlatformSpecificImplementation<
-          AndroidFlutterLocalNotificationsPlugin
-        >()
-        ?.createNotificationChannel(androidChannel);
+    try {
+      await _notifications
+          .resolvePlatformSpecificImplementation<
+            AndroidFlutterLocalNotificationsPlugin
+          >()
+          ?.createNotificationChannel(androidChannel);
+    } catch (e) {
+      AppLogger.debug('안드로이드 채널 생성 실패: $e');
+    }
   }
 
   /// 알림 권한 요청
@@ -214,6 +218,46 @@ class NotificationService {
     return true;
   }
 
+  /// 정확 알람 권한 가능 여부 확인 (Android 12+)
+  Future<bool> canScheduleExactAlarms() async {
+    if (kIsWeb || defaultTargetPlatform != TargetPlatform.android) {
+      return true;
+    }
+
+    try {
+      final androidImplementation = _notifications
+          .resolvePlatformSpecificImplementation<
+            AndroidFlutterLocalNotificationsPlugin
+          >();
+      final canExact = await androidImplementation
+          ?.canScheduleExactNotifications();
+      return canExact ?? true;
+    } catch (e) {
+      AppLogger.debug('정확 알람 권한 확인 실패: $e');
+      return false;
+    }
+  }
+
+  /// 정확 알람 권한 요청 (Android 12+ 설정 화면 이동)
+  Future<bool> requestExactAlarmsPermission() async {
+    if (kIsWeb || defaultTargetPlatform != TargetPlatform.android) {
+      return true;
+    }
+
+    try {
+      final androidImplementation = _notifications
+          .resolvePlatformSpecificImplementation<
+            AndroidFlutterLocalNotificationsPlugin
+          >();
+      final granted = await androidImplementation
+          ?.requestExactAlarmsPermission();
+      return granted ?? false;
+    } catch (e) {
+      AppLogger.debug('정확 알람 권한 요청 실패: $e');
+      return false;
+    }
+  }
+
   // 알림 탭 콜백
   static void Function(NotificationResponse)? onNotificationTap;
 
@@ -238,7 +282,7 @@ class NotificationService {
       }
 
       final location = await _ensureLocalTimezone();
-      final minutesToWait = delayMinutes ?? 90 + Random().nextInt(31);
+      final minutesToWait = max(delayMinutes ?? 90 + Random().nextInt(31), 1);
       final scheduledTime = tz.TZDateTime.now(
         location,
       ).add(Duration(minutes: minutesToWait));
@@ -343,17 +387,9 @@ class NotificationService {
       return AndroidScheduleMode.exactAllowWhileIdle;
     }
 
-    try {
-      final androidImplementation = _notifications
-          .resolvePlatformSpecificImplementation<
-            AndroidFlutterLocalNotificationsPlugin
-          >();
-      final canExact = await androidImplementation
-          ?.canScheduleExactNotifications();
-      if (canExact == false) {
-        return AndroidScheduleMode.inexactAllowWhileIdle;
-      }
-    } catch (_) {
+    final canExact = await canScheduleExactAlarms();
+    if (!canExact) {
+      AppLogger.debug('정확 알람 권한 없음 → 근사 모드로 예약');
       return AndroidScheduleMode.inexactAllowWhileIdle;
     }
 

lib/presentation/pages/settings/settings_screen.dart

@@ -6,6 +6,7 @@ import 'package:permission_handler/permission_handler.dart';
 import '../../../core/constants/app_colors.dart';
 import '../../../core/constants/app_typography.dart';
 import '../../providers/settings_provider.dart';
+import '../../providers/notification_provider.dart';
 
 class SettingsScreen extends ConsumerStatefulWidget {
   const SettingsScreen({super.key});
@@ -174,6 +175,29 @@ class _SettingsScreenState extends ConsumerState<SettingsScreen> {
                 );
               },
             ),
+            if (!kIsWeb && defaultTargetPlatform == TargetPlatform.android)
+              FutureBuilder<bool>(
+                future: ref
+                    .read(notificationServiceProvider)
+                    .canScheduleExactAlarms(),
+                builder: (context, snapshot) {
+                  final canExact = snapshot.data;
+
+                  // 권한이 이미 허용된 경우 UI 생략
+                  if (canExact == true) {
+                    return const SizedBox.shrink();
+                  }
+
+                  return _buildPermissionTile(
+                    icon: Icons.alarm,
+                    title: '정확 알람 권한',
+                    subtitle: '정확한 예약 알림을 위해 필요합니다',
+                    isGranted: canExact ?? false,
+                    onRequest: _requestExactAlarmPermission,
+                    isDark: isDark,
+                  );
+                },
+              ),
           ], isDark),
 
           // 알림 설정
@@ -407,6 +431,19 @@ class _SettingsScreenState extends ConsumerState<SettingsScreen> {
     }
   }
 
+  Future<void> _requestExactAlarmPermission() async {
+    final notificationService = ref.read(notificationServiceProvider);
+    final granted = await notificationService.requestExactAlarmsPermission();
+
+    if (!mounted) return;
+
+    setState(() {});
+
+    if (!granted) {
+      _showPermissionDialog('정확 알람');
+    }
+  }
+
   void _showPermissionDialog(String permissionName) {
     final isDark = Theme.of(context).brightness == Brightness.dark;