feat(flutter): add action buttons to desktop download notifications

Terminal task notifications now carry actionable buttons and respond to
clicks instead of being inert:

- Done notifications offer Open File and Open Folder for single-file
  tasks, and Open Folder only for folder tasks (e.g. multi-file
  torrents), following the same rule as the task details page. Error
  notifications offer Open Folder only, since the output is rarely
  usable.
- Clicking the notification body brings the app window back to the
  front (show + focus), covering the close-to-tray case.
- The click target is snapshotted into the notification (Windows: action
  arguments; macOS/Linux: notification payload) so buttons keep working
  after the task record is deleted, and a missing file is logged instead
  of surfacing an OS error dialog.
- macOS resolves buttons through three pre-registered notification
  categories (done single-file / done folder / error); Windows uses the
  actions API of the pinned notification plugin fork; Linux uses
  freedesktop notification actions.
- New openFolder label localized in all 22 ARB catalogs.

Cold-start activation is intentionally out of scope: when the process is
not running, OS activation opens the main window without dispatching the
button action.

ui/flutter/lib/app/application/app_notification_controller.dart

@@ -1,13 +1,19 @@
 import 'dart:async';
+import 'dart:convert';
 import 'dart:io';
 
 import 'package:flutter/foundation.dart';
 import 'package:flutter_local_notifications/flutter_local_notifications.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:path/path.dart' as path;
+import 'package:window_manager/window_manager.dart';
 
+import '../../api/model/task.dart' as api_task;
+import '../../core/capabilities/app_capabilities.dart';
 import '../../core/common/task_event.dart';
 import '../../core/libgopeed_boot.dart';
+import '../../core/utils/file_explorer.dart';
+import '../../features/tasks/domain/task_record.dart';
 import '../../l10n/l10n.dart';
 import '../../util/log_util.dart';
 import '../../util/util.dart';
@@ -17,6 +23,45 @@ final appNotificationControllerProvider = AsyncNotifierProvider<AppNotificationC
   AppNotificationController.new,
 );
 
+const _openFileAction = 'open_file';
+const _openFolderAction = 'open_folder';
+
+// macOS resolves buttons through pre-registered notification categories, one
+// per action combination a terminal task event can offer.
+const _categoryDoneSingleFile = 'taskDoneSingleFile';
+const _categoryDoneFolder = 'taskDoneFolder';
+const _categoryTaskError = 'taskTaskError';
+
+/// A notification button resolved for one task event.
+///
+/// [id] is one of [_openFileAction]/[_openFolderAction]; Windows carries
+/// [path] inside the action arguments, macOS and Linux deliver it through the
+/// notification payload, so the click callback can act without looking the
+/// task up again (it may already be gone by the time the user clicks).
+class NotificationActionSpec {
+  const NotificationActionSpec({required this.id, required this.path});
+
+  final String id;
+  final String path;
+
+  String encode() => jsonEncode({'action': id, 'path': path});
+
+  static NotificationActionSpec? decode(String raw) {
+    if (raw.isEmpty) return null;
+    try {
+      final data = jsonDecode(raw);
+      if (data is! Map<String, dynamic>) return null;
+      final id = data['action'];
+      final targetPath = data['path'];
+      if (id is! String || targetPath is! String) return null;
+      if (id != _openFileAction && id != _openFolderAction) return null;
+      return NotificationActionSpec(id: id, path: targetPath);
+    } catch (_) {
+      return null;
+    }
+  }
+}
+
 class AppNotificationState {
   const AppNotificationState({this.started = false});
 
@@ -51,10 +96,17 @@ class AppNotificationController extends AsyncNotifier<AppNotificationState> {
   Future<void> _initNotifications(AppLocalizations locale, {required bool requestPermissions}) async {
     // The runtime is watched, so enabling notifications in settings also
     // requests authorization. macOS remembers previously granted/denied access.
+    final openFileAction = DarwinNotificationAction.plain(_openFileAction, locale.openFile);
+    final openFolderAction = DarwinNotificationAction.plain(_openFolderAction, locale.openFolder);
     final darwin = DarwinInitializationSettings(
       requestAlertPermission: requestPermissions,
       requestBadgePermission: false,
       requestSoundPermission: requestPermissions,
+      notificationCategories: [
+        DarwinNotificationCategory(_categoryDoneSingleFile, actions: [openFileAction, openFolderAction]),
+        DarwinNotificationCategory(_categoryDoneFolder, actions: [openFolderAction]),
+        DarwinNotificationCategory(_categoryTaskError, actions: [openFolderAction]),
+      ],
     );
     final linux = LinuxInitializationSettings(
       defaultActionName: locale.open,
@@ -95,6 +147,7 @@ class AppNotificationController extends AsyncNotifier<AppNotificationState> {
 
     await _plugin.initialize(
       settings: InitializationSettings(macOS: darwin, linux: linux, windows: windows),
+      onDidReceiveNotificationResponse: _onNotificationResponse,
     );
   }
 
@@ -106,19 +159,142 @@ class AppNotificationController extends AsyncNotifier<AppNotificationState> {
       final locale = appLocalizationsFor(runtime?.downloaderConfig.extra.locale ?? '');
       switch (event.type) {
         case TaskEventType.done:
-          await _showNotification(title: locale.notificationTaskDone, body: event.name);
+          await _showNotification(
+            locale: locale,
+            title: locale.notificationTaskDone,
+            body: event.name,
+            taskId: event.taskId,
+            allowOpenFile: true,
+          );
         case TaskEventType.error:
-          await _showNotification(title: locale.notificationTaskError, body: event.name);
+          await _showNotification(
+            locale: locale,
+            title: locale.notificationTaskError,
+            body: event.name,
+            taskId: event.taskId,
+            // A failed download rarely has a usable output file to open.
+            allowOpenFile: false,
+          );
       }
     });
   }
 
-  Future<void> _showNotification({required String title, required String body}) async {
-    const details = NotificationDetails(
-      macOS: DarwinNotificationDetails(),
-      linux: LinuxNotificationDetails(),
-      windows: WindowsNotificationDetails(),
+  Future<void> _showNotification({
+    required AppLocalizations locale,
+    required String title,
+    required String body,
+    required String taskId,
+    required bool allowOpenFile,
+  }) async {
+    final target = await resolveTaskTarget(taskId, allowOpenFile: allowOpenFile);
+    final payload = target == null ? '' : jsonEncode({'path': target.path});
+    final details = NotificationDetails(
+      macOS: DarwinNotificationDetails(
+        categoryIdentifier: switch (target) {
+          null => null,
+          _ when target.canOpenFile => _categoryDoneSingleFile,
+          _ when allowOpenFile => _categoryDoneFolder,
+          _ => _categoryTaskError,
+        },
+      ),
+      linux: LinuxNotificationDetails(
+        actions: [
+          if (target != null && target.canOpenFile)
+            LinuxNotificationAction(key: _openFileAction, label: locale.openFile),
+          if (target != null) LinuxNotificationAction(key: _openFolderAction, label: locale.openFolder),
+        ],
+      ),
+      windows: WindowsNotificationDetails(
+        actions: [
+          if (target != null && target.canOpenFile)
+            WindowsAction(content: locale.openFile, arguments: NotificationActionSpec(id: _openFileAction, path: target.path).encode()),
+          if (target != null)
+            WindowsAction(content: locale.openFolder, arguments: NotificationActionSpec(id: _openFolderAction, path: target.path).encode()),
+        ],
+      ),
     );
-    await _plugin.show(id: _notificationId++, title: title, body: body, notificationDetails: details);
+    await _plugin.show(id: _notificationId++, title: title, body: body, notificationDetails: details, payload: payload);
+  }
+
+  /// Resolves the download target a terminal task event points at, following
+  /// the same rule as the task details page: only single-file tasks offer
+  /// "open file", folder tasks (e.g. multi-file torrents) can only reveal the
+  /// folder. Returns null when the task is already gone.
+  @visibleForTesting
+  Future<({String path, bool canOpenFile})?> resolveTaskTarget(
+    String taskId, {
+    required bool allowOpenFile,
+  }) async {
+    final apiTask = await findTask(taskId);
+    if (apiTask == null) return null;
+    final record = TaskRecord.fromApi(apiTask);
+    return (path: record.storagePath, canOpenFile: allowOpenFile && !record.isFolder);
+  }
+
+  @visibleForTesting
+  Future<void> handleNotificationResponse(NotificationResponse response) => _onNotificationResponse(response);
+
+  Future<void> _onNotificationResponse(NotificationResponse response) async {
+    // Windows actions carry the full spec in their arguments.
+    var spec = NotificationActionSpec.decode(response.actionId ?? '');
+    if (spec == null) {
+      // macOS/Linux actions are stable keys; the path arrives in the payload.
+      final id = response.actionId ?? '';
+      if (id == _openFileAction || id == _openFolderAction) {
+        try {
+          final data = jsonDecode(response.payload ?? '');
+          final targetPath = data is Map<String, dynamic> ? data['path'] : null;
+          if (targetPath is String) {
+            spec = NotificationActionSpec(id: id, path: targetPath);
+          }
+        } catch (_) {
+          // Malformed payload: fall through to the plain-click behavior.
+        }
+      }
+    }
+    if (spec == null) {
+      // Plain click on the notification body: bring the app window back.
+      await bringWindowToFront();
+      return;
+    }
+    if (!await File(spec.path).exists()) {
+      logger.w('notification target no longer exists: ${spec.path}');
+      return;
+    }
+    switch (spec.id) {
+      case _openFileAction:
+        if (!await openTaskFile(spec.path)) {
+          logger.w('failed to open file from notification: ${spec.path}');
+        }
+      case _openFolderAction:
+        if (!await revealTaskFolder(spec.path)) {
+          logger.w('failed to reveal folder from notification: ${spec.path}');
+        }
+    }
+  }
+
+  @visibleForTesting
+  Future<api_task.Task?> findTask(String taskId) async {
+    try {
+      final tasks = await ref.read(gopeedServiceProvider).getTasks(api_task.Status.values);
+      for (final task in tasks) {
+        if (task.id == taskId) return task;
+      }
+    } catch (error, stackTrace) {
+      logger.w('look up task for notification failed', error, stackTrace);
+    }
+    return null;
+  }
+
+  @visibleForTesting
+  Future<bool> openTaskFile(String filePath) => FileExplorer.open(filePath);
+
+  @visibleForTesting
+  Future<bool> revealTaskFolder(String filePath) => FileExplorer.reveal(filePath);
+
+  @visibleForTesting
+  Future<void> bringWindowToFront() async {
+    await windowManager.show();
+    await windowManager.focus();
   }
 }

ui/flutter/lib/l10n/app_ar.arb

@@ -239,6 +239,7 @@
   "back": "رجوع",
   "open": "فتح",
   "openFile": "فتح الملف",
+  "openFolder": "فتح المجلد",
   "share": "مشاركة",
   "copy": "نسخ",
   "copied": "مُزَوَّل",

ui/flutter/lib/l10n/app_az.arb

@@ -253,6 +253,7 @@
   "back": "Geri",
   "open": "Aç",
   "openFile": "Faylı Aç",
+  "openFolder": "Qovluğu Aç",
   "share": "Paylaş",
   "copy": "Kopyala",
   "copied": "Kopyalandı",

ui/flutter/lib/l10n/app_ca.arb

@@ -239,6 +239,7 @@
   "back": "Enrere",
   "open": "Obre",
   "openFile": "Obre el fitxer",
+  "openFolder": "Obre la carpeta",
   "share": "Comparteix",
   "copy": "Copia",
   "copied": "Copiat",

ui/flutter/lib/l10n/app_de.arb

@@ -239,6 +239,7 @@
   "back": "Zurück",
   "open": "Offen",
   "openFile": "Datei öffnen",
+  "openFolder": "Ordner öffnen",
   "share": "Teilen",
   "copy": "Kopie",
   "copied": "Kopiert",

ui/flutter/lib/l10n/app_en.arb

@@ -261,6 +261,7 @@
   "back": "Back",
   "open": "Open",
   "openFile": "Open File",
+  "openFolder": "Open Folder",
   "share": "Share",
   "copy": "Copy",
   "copied": "Copied",

ui/flutter/lib/l10n/app_es.arb

@@ -239,6 +239,7 @@
   "back": "Volver",
   "open": "Abrir",
   "openFile": "Abrir archivo",
+  "openFolder": "Abrir carpeta",
   "share": "Compartir",
   "copy": "Copiar",
   "copied": "Copiado",

ui/flutter/lib/l10n/app_fa.arb

@@ -239,6 +239,7 @@
   "back": "بازگشت",
   "open": "باز کردن",
   "openFile": "باز کردن فایل",
+  "openFolder": "باز کردن پوشه",
   "share": "اشتراک‌گذاری",
   "copy": "کپی",
   "copied": "اخراج",

ui/flutter/lib/l10n/app_fr.arb

@@ -239,6 +239,7 @@
   "back": "Retour",
   "open": "Ouvrir",
   "openFile": "Ouvrir le fichier",
+  "openFolder": "Ouvrir le dossier",
   "share": "Partager",
   "copy": "Copier",
   "copied": "Copied",

ui/flutter/lib/l10n/app_hu.arb

@@ -239,6 +239,7 @@
   "back": "Vissza",
   "open": "Nyitva",
   "openFile": "Fájl megnyitása",
+  "openFolder": "Mappa megnyitása",
   "share": "Megosztás",
   "copy": "másolat",
   "copied": "Másolva",

ui/flutter/lib/l10n/app_id.arb

@@ -239,6 +239,7 @@
   "back": "Kembali",
   "open": "Buka",
   "openFile": "Buka Berkas",
+  "openFolder": "Buka Folder",
   "share": "Bagikan",
   "copy": "Salin",
   "copied": "Disalin",

ui/flutter/lib/l10n/app_it.arb

@@ -239,6 +239,7 @@
   "back": "Indietro",
   "open": "Apri",
   "openFile": "Apri file",
+  "openFolder": "Apri cartella",
   "share": "Condividi",
   "copy": "Copia",
   "copied": "- Si'",

ui/flutter/lib/l10n/app_ja.arb

@@ -239,6 +239,7 @@
   "back": "戻る",
   "open": "営業部",
   "openFile": "ファイルを開く",
+  "openFolder": "フォルダを開く",
   "share": "共有",
   "copy": "コピー",
   "copied": "コピー",

ui/flutter/lib/l10n/app_ko.arb

@@ -239,6 +239,7 @@
   "back": "뒤로",
   "open": "열기",
   "openFile": "파일 열기",
+  "openFolder": "폴더 열기",
   "share": "공유",
   "copy": "복사",
   "copied": "뚱 베어",

ui/flutter/lib/l10n/app_pl.arb

@@ -239,6 +239,7 @@
   "back": "Wstecz",
   "open": "Otwórz",
   "openFile": "Otwórz plik",
+  "openFolder": "Otwórz folder",
   "share": "Udostępnij",
   "copy": "Kopiuj",
   "copied": "Kopiowane",

ui/flutter/lib/l10n/app_pt.arb

@@ -239,6 +239,7 @@
   "back": "Voltar",
   "open": "Abrir",
   "openFile": "Abrir ficheiro",
+  "openFolder": "Abrir pasta",
   "share": "Partilhar",
   "copy": "Copiar",
   "copied": "Copiado",

ui/flutter/lib/l10n/app_ru.arb

@@ -239,6 +239,7 @@
   "back": "Назад",
   "open": "Открыть",
   "openFile": "Открыть файл",
+  "openFolder": "Открыть папку",
   "share": "Поделиться",
   "copy": "Копия",
   "copied": "Копирован",

ui/flutter/lib/l10n/app_ta.arb

@@ -239,6 +239,7 @@
   "back": "பின்செல்",
   "open": "திற",
   "openFile": "கோப்பைத் திற",
+  "openFolder": "கோப்புறையைத் திற",
   "share": "பகிர்",
   "copy": "நகலெடு",
   "copied": "நகலெடுக்கப்பட்டது",

ui/flutter/lib/l10n/app_tr.arb

@@ -239,6 +239,7 @@
   "back": "Geri",
   "open": "Aç",
   "openFile": "Dosyayı Aç",
+  "openFolder": "Klasörü Aç",
   "share": "Paylaş",
   "copy": "Kopyala",
   "copied": "Kopyalandı",

ui/flutter/lib/l10n/app_uk.arb

@@ -239,6 +239,7 @@
   "back": "Назад",
   "open": "Відкрито",
   "openFile": "Відкрити файл",
+  "openFolder": "Відкрити папку",
   "share": "Поділитися",
   "copy": "Список",
   "copied": "Панчохи",

ui/flutter/lib/l10n/app_vi.arb

@@ -239,6 +239,7 @@
   "back": "Quay lại",
   "open": "Mở",
   "openFile": "Mở tệp",
+  "openFolder": "Mở thư mục",
   "share": "Chia sẻ",
   "copy": "Chép",
   "copied": "Co dãn",

ui/flutter/lib/l10n/app_zh.arb

@@ -239,6 +239,7 @@
   "back": "返回",
   "open": "打开",
   "openFile": "打开文件",
+  "openFolder": "打开文件夹",
   "share": "分享",
   "copy": "复制",
   "copied": "已复制",

ui/flutter/lib/l10n/app_zh_TW.arb

@@ -239,6 +239,7 @@
   "back": "返回",
   "open": "開啟",
   "openFile": "開啟檔案",
+  "openFolder": "開啟資料夾",
   "share": "分享",
   "copy": "複製",
   "copied": "已複製",

ui/flutter/test/app/application/app_notification_controller_test.dart

@@ -1,4 +1,5 @@
 import 'dart:async';
+import 'dart:io';
 
 import 'package:flutter/foundation.dart';
 import 'package:flutter/services.dart';
@@ -6,6 +7,11 @@ import 'package:flutter_local_notifications/flutter_local_notifications.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:gopeed/api/model/downloader_config.dart';
+import 'package:gopeed/api/model/meta.dart';
+import 'package:gopeed/api/model/options.dart';
+import 'package:gopeed/api/model/request.dart';
+import 'package:gopeed/api/model/resource.dart';
+import 'package:gopeed/api/model/task.dart' as api_task;
 import 'package:gopeed/app/application/app_notification_controller.dart';
 import 'package:gopeed/app/application/app_runtime_controller.dart';
 import 'package:gopeed/core/common/api_server_state.dart';
@@ -52,6 +58,9 @@ void main() {
 
   Map<dynamic, dynamic> initialization() => calls.lastWhere((call) => call.method == 'initialize').arguments as Map;
 
+  List<Map<dynamic, dynamic>> shownNotifications() =>
+      calls.where((call) => call.method == 'show').map((call) => call.arguments as Map).toList();
+
   test('macOS requests alerts and sound when download notifications are enabled at startup', () async {
     await start(enabled: true);
 
@@ -101,9 +110,9 @@ void main() {
     events.add(done);
     events.add(const TaskEvent(type: TaskEventType.error, taskId: '2', name: 'failed.zip'));
     await Future<void>.delayed(Duration.zero);
-    final notifications = calls.where((call) => call.method == 'show').toList();
+    final notifications = shownNotifications();
     expect(notifications, hasLength(2));
-    expect(notifications.map((call) => (call.arguments as Map)['body']), ['archive.zip', 'failed.zip']);
+    expect(notifications.map((call) => call['body']), ['archive.zip', 'failed.zip']);
 
     runtime.setNotificationsEnabled(false);
     await container.pump();
@@ -112,6 +121,138 @@ void main() {
     await Future<void>.delayed(Duration.zero);
     expect(calls.where((call) => call.method == 'show'), hasLength(2));
   });
+
+  test('macOS registers action categories for every terminal event combination', () async {
+    await start(enabled: true);
+
+    final categories = initialization()['notificationCategories'] as List<dynamic>;
+    final identifiers = categories.map((category) => (category as Map)['identifier']).toList();
+    expect(identifiers, containsAll(['taskDoneSingleFile', 'taskDoneFolder', 'taskTaskError']));
+    final singleFile = categories.firstWhere((c) => c['identifier'] == 'taskDoneSingleFile') as Map;
+    final singleActions = (singleFile['actions'] as List).cast<Map>();
+    expect(singleActions.map((action) => action['identifier']), ['open_file', 'open_folder']);
+    expect(singleActions.map((action) => action['title']), ['Open File', 'Open Folder']);
+  });
+
+  test('a done single-file task resolves an open-file target', () async {
+    final container = await start(enabled: true);
+    final notifier = container.read(appNotificationControllerProvider.notifier) as _TestNotificationController;
+
+    final target = await notifier.resolveTaskTarget('single', allowOpenFile: true);
+
+    expect(target?.path, '/downloads/archive.zip');
+    expect(target?.canOpenFile, isTrue);
+  });
+
+  test('a folder task never resolves an open-file target', () async {
+    final container = await start(enabled: true);
+    final notifier = container.read(appNotificationControllerProvider.notifier) as _TestNotificationController;
+
+    final target = await notifier.resolveTaskTarget('folder', allowOpenFile: true);
+
+    expect(target?.path, '/downloads/torrent-bundle');
+    expect(target?.canOpenFile, isFalse);
+  });
+
+  test('an errored task never resolves an open-file target', () async {
+    final container = await start(enabled: true);
+    final notifier = container.read(appNotificationControllerProvider.notifier) as _TestNotificationController;
+
+    final target = await notifier.resolveTaskTarget('single', allowOpenFile: false);
+
+    expect(target?.canOpenFile, isFalse);
+  });
+
+  test('a done single-file task notification selects the single-file category and payload path', () async {
+    await start(enabled: true);
+    events.add(const TaskEvent(type: TaskEventType.done, taskId: 'single', name: 'archive.zip'));
+    await Future<void>.delayed(Duration.zero);
+
+    final notifications = shownNotifications();
+    expect(notifications, hasLength(1));
+    final platformSpecifics = notifications[0]['platformSpecifics'] as Map<dynamic, dynamic>;
+    expect(platformSpecifics['categoryIdentifier'], 'taskDoneSingleFile');
+    expect(notifications[0]['payload'], '{"path":"/downloads/archive.zip"}');
+  });
+
+  test('a done folder task notification selects the folder category', () async {
+    await start(enabled: true);
+    events.add(const TaskEvent(type: TaskEventType.done, taskId: 'folder', name: 'torrent-bundle'));
+    await Future<void>.delayed(Duration.zero);
+
+    final platformSpecifics = shownNotifications()[0]['platformSpecifics'] as Map<dynamic, dynamic>;
+    expect(platformSpecifics['categoryIdentifier'], 'taskDoneFolder');
+  });
+
+  test('an errored task notification selects the error category', () async {
+    await start(enabled: true);
+    events.add(const TaskEvent(type: TaskEventType.error, taskId: 'single', name: 'archive.zip'));
+    await Future<void>.delayed(Duration.zero);
+
+    final platformSpecifics = shownNotifications()[0]['platformSpecifics'] as Map<dynamic, dynamic>;
+    expect(platformSpecifics['categoryIdentifier'], 'taskTaskError');
+  });
+
+  test('action responses route to file and folder handlers by encoded spec', () async {
+    final container = await start(enabled: true);
+    final notifier = container.read(appNotificationControllerProvider.notifier) as _TestNotificationController;
+    final existingPath = '${Directory.systemTemp.path}/gopeed-notification-test.zip';
+    addTearDown(() => File(existingPath).deleteSync());
+    File(existingPath).writeAsStringSync('data');
+
+    // Windows style: the action arguments carry the full spec.
+    await notifier.handleNotificationResponse(
+      NotificationResponse(
+        notificationResponseType: NotificationResponseType.selectedNotificationAction,
+        actionId: NotificationActionSpec(id: 'open_file', path: existingPath).encode(),
+      ),
+    );
+    expect(notifier.openedFiles, [existingPath]);
+    expect(notifier.revealedFolders, isEmpty);
+    expect(notifier.frontedWindow, isFalse);
+
+    // macOS/Linux style: stable action key plus the notification payload path.
+    await notifier.handleNotificationResponse(
+      NotificationResponse(
+        notificationResponseType: NotificationResponseType.selectedNotificationAction,
+        actionId: 'open_folder',
+        payload: '{"path":"$existingPath"}',
+      ),
+    );
+    expect(notifier.revealedFolders, [existingPath]);
+    expect(notifier.frontedWindow, isFalse);
+  });
+
+  test('a plain notification body click brings the app window to the front', () async {
+    final container = await start(enabled: true);
+    final notifier = container.read(appNotificationControllerProvider.notifier) as _TestNotificationController;
+
+    await notifier.handleNotificationResponse(
+      const NotificationResponse(notificationResponseType: NotificationResponseType.selectedNotification),
+    );
+
+    expect(notifier.frontedWindow, isTrue);
+    expect(notifier.openedFiles, isEmpty);
+    expect(notifier.revealedFolders, isEmpty);
+  });
+}
+
+api_task.Task _task(String id, {required bool folder}) {
+  final task = api_task.Task(
+    id: id,
+    name: folder ? 'torrent-bundle' : 'archive.zip',
+    meta: Meta(
+      req: Request(url: 'https://example.com/archive.zip'),
+      opts: Options(path: '/downloads'),
+    ),
+    status: api_task.Status.done,
+    uploading: false,
+    progress: api_task.Progress(used: 0, speed: 0, downloaded: 1, uploadSpeed: 0, uploaded: 0),
+    createdAt: DateTime(2026),
+    updatedAt: DateTime(2026),
+  );
+  task.meta.res = Resource(name: folder ? 'torrent-bundle' : '', files: const []);
+  return task;
 }
 
 class _TestNotificationController extends AppNotificationController {
@@ -119,6 +260,34 @@ class _TestNotificationController extends AppNotificationController {
 
   @override
   final Stream<TaskEvent> taskEvents;
+
+  final tasksById = {
+    'single': _task('single', folder: false),
+    'folder': _task('folder', folder: true),
+  };
+  final openedFiles = <String>[];
+  final revealedFolders = <String>[];
+  var frontedWindow = false;
+
+  @override
+  Future<api_task.Task?> findTask(String taskId) async => tasksById[taskId];
+
+  @override
+  Future<bool> openTaskFile(String filePath) async {
+    openedFiles.add(filePath);
+    return true;
+  }
+
+  @override
+  Future<bool> revealTaskFolder(String filePath) async {
+    revealedFolders.add(filePath);
+    return true;
+  }
+
+  @override
+  Future<void> bringWindowToFront() async {
+    frontedWindow = true;
+  }
 }
 
 class _TestRuntimeController extends AppRuntimeController {