feat(tasks): group extension folder downloads (#1594)

ui/flutter/test/api/resolve_test.dart

@@ -3,6 +3,7 @@ import 'dart:convert';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:gopeed/api/api.dart' as api;
 import 'package:gopeed/api/model/create_task.dart';
+import 'package:gopeed/api/model/create_task_batch.dart';
 import 'package:gopeed/api/model/options.dart';
 import 'package:gopeed/api/model/patch_task.dart';
 import 'package:gopeed/api/model/request.dart';
@@ -39,6 +40,32 @@ void main() {
     expect((createBody['opts'] as Map<String, dynamic>)['selectFiles'], [1]);
   });
 
+  test('batch sends rid and options and decodes the unified response in both modes', () async {
+    for (final grouped in [false, true]) {
+      final transport = _RecordingTransport();
+      api.setTransportForTesting(transport);
+      final result = await api.createTaskBatch(
+        CreateTaskBatch(
+          group: grouped,
+          groupName: grouped ? 'folder' : '',
+          reqs: [
+            CreateTaskBatchItem(
+              rid: 'resolved-id',
+              opts: Options(selectFiles: [1]),
+            ),
+          ],
+        ),
+      );
+      expect(result.taskIds, ['created-id']);
+      expect(result.parentId, grouped ? 'parent' : null);
+      final body = transport.data as Map<String, dynamic>;
+      final member = (body['reqs'] as List).single as Map<String, dynamic>;
+      expect(member['rid'], 'resolved-id');
+      expect((member['opts'] as Map)['selectFiles'], [1]);
+      expect(body, isNot(contains('groupId')));
+    }
+  });
+
   test('patch preserves options in its independent request model', () async {
     final transport = _RecordingTransport();
     api.setTransportForTesting(transport);
@@ -59,6 +86,15 @@ class _RecordingTransport implements GopeedTransport {
     Map<String, dynamic>? queryParameters,
   }) async {
     this.data = jsonDecode(jsonEncode(data));
+    if (path == 'api/v1/tasks/batch') {
+      return {
+        'code': 0,
+        'data': {
+          'taskIds': ['created-id'],
+          if (this.data['group'] == true) 'parentId': 'parent',
+        },
+      };
+    }
     if (path == 'api/v1/tasks') {
       return {'code': 0, 'data': 'created-id'};
     }