Allow OS notifications

lib/services/notification_service.dart

@@ -0,0 +1,56 @@
+import 'package:flutter_local_notifications/flutter_local_notifications.dart';
+
+/// A thin wrapper around `flutter_local_notifications` that centralizes the
+/// plugin instance and provides easy initialization/show helpers.
+class NotificationService {
+  NotificationService._();
+
+  static final FlutterLocalNotificationsPlugin _plugin =
+      FlutterLocalNotificationsPlugin();
+
+  /// Call during app startup, after any necessary permissions have been
+  /// granted.  The callback receives a [NotificationResponse] when the user
+  /// taps the alert.
+  static Future<void> initialize({
+    void Function(NotificationResponse)? onDidReceiveNotificationResponse,
+  }) async {
+    const androidSettings = AndroidInitializationSettings(
+      '@mipmap/ic_launcher',
+    );
+    const iosSettings = DarwinInitializationSettings();
+
+    await _plugin.initialize(
+      settings: const InitializationSettings(
+        android: androidSettings,
+        iOS: iosSettings,
+      ),
+      onDidReceiveNotificationResponse: onDidReceiveNotificationResponse,
+    );
+  }
+
+  /// Show a simple notification immediately.
+  static Future<void> show({
+    required int id,
+    required String title,
+    required String body,
+    String? payload,
+  }) async {
+    const androidDetails = AndroidNotificationDetails(
+      'default_channel',
+      'General',
+      importance: Importance.high,
+      priority: Priority.high,
+    );
+    const iosDetails = DarwinNotificationDetails();
+    await _plugin.show(
+      id: id,
+      title: title,
+      body: body,
+      notificationDetails: const NotificationDetails(
+        android: androidDetails,
+        iOS: iosDetails,
+      ),
+      payload: payload,
+    );
+  }
+}

lib/services/permission_service.dart

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+import 'package:permission_handler/permission_handler.dart';
+
+/// Information about a permission that the application cares about.
+///
+/// Add new entries to [appPermissions] when the app requires additional
+/// runtime permissions. The UI that drives the "permissions screen" reads this
+/// list and will automatically include new permissions without any further
+/// changes.
+class PermissionInfo {
+  const PermissionInfo({
+    required this.permission,
+    required this.label,
+    this.description,
+  });
+
+  final Permission permission;
+  final String label;
+  final String? description;
+}
+
+/// The set of permissions the app will check/request from the user.
+///
+/// Currently contains the permissions actually referenced in the codebase, but
+/// it should be expanded as new features are added.  Declaring a permission
+/// here ensures it appears on the permissions screen and is considered when
+/// performing bulk checks/requests.
+const List<PermissionInfo> appPermissions = [
+  PermissionInfo(
+    permission: Permission.notification,
+    label: 'Notifications',
+    description: 'Deliver alerts and sounds',
+  ),
+  PermissionInfo(
+    permission: Permission.location,
+    label: 'Location',
+    description: 'Access your location for geofencing',
+  ),
+  // add new permissions here as necessary
+];
+
+/// Returns the current status for every permission in [appPermissions].
+Future<Map<Permission, PermissionStatus>> getAllStatuses() async {
+  final map = <Permission, PermissionStatus>{};
+  for (final info in appPermissions) {
+    map[info.permission] = await info.permission.status;
+  }
+  return map;
+}
+
+/// Requests [permission] and returns the resulting status.
+Future<PermissionStatus> requestPermission(Permission permission) async {
+  return permission.request();
+}
+
+/// Convenience that requests every permission that is currently not granted.
+///
+/// Returns the full status map after requesting.
+Future<Map<Permission, PermissionStatus>> requestAllNeeded() async {
+  final statuses = await getAllStatuses();
+  for (final entry in statuses.entries) {
+    if (!entry.value.isGranted) {
+      statuses[entry.key] = await entry.key.request();
+    }
+  }
+  return statuses;
+}