feat(api): Optimize conversation parsing with worker-based decoding

lib/core/services/api_service.dart

@@ -911,6 +911,26 @@ class ApiService {
     return [];
   }
 
+  Future<List<Conversation>> _parseConversationSummaryList(
+    List<dynamic> regular, {
+    required String debugLabel,
+  }) async {
+    final payload = <String, dynamic>{
+      'regular': List<dynamic>.from(regular),
+      'pinned': const <dynamic>[],
+      'archived': const <dynamic>[],
+    };
+    final parsed = await _workerManager
+        .schedule<Map<String, dynamic>, List<Map<String, dynamic>>>(
+          parseConversationSummariesWorker,
+          payload,
+          debugLabel: debugLabel,
+        );
+    return parsed
+        .map((json) => Conversation.fromJson(json))
+        .toList(growable: false);
+  }
+
   // Tools - Check available tools on server
   Future<List<Map<String, dynamic>>> getAvailableTools() async {
     _traceApi('Fetching available tools');
@@ -1005,10 +1025,10 @@ class ApiService {
     final response = await _dio.get('/api/v1/chats/folder/$folderId');
     final data = response.data;
     if (data is List) {
-      return data.whereType<Map>().map((chatData) {
-        final map = Map<String, dynamic>.from(chatData);
-        return Conversation.fromJson(parseConversationSummary(map));
-      }).toList();
+      return _parseConversationSummaryList(
+        data,
+        debugLabel: 'parse_folder_$folderId',
+      );
     }
     return [];
   }
@@ -1052,10 +1072,7 @@ class ApiService {
     final response = await _dio.get('/api/v1/chats/tags/$tag');
     final data = response.data;
     if (data is List) {
-      return data.whereType<Map>().map((chatData) {
-        final map = Map<String, dynamic>.from(chatData);
-        return Conversation.fromJson(parseConversationSummary(map));
-      }).toList();
+      return _parseConversationSummaryList(data, debugLabel: 'parse_tag_$tag');
     }
     return [];
   }
@@ -2738,8 +2755,11 @@ class ApiService {
       '/api/v1/chats/search',
       queryParameters: {'q': query},
     );
-    final results = response.data as List;
-    return results.map((c) => Conversation.fromJson(c)).toList();
+    final results = response.data;
+    if (results is List) {
+      return _parseConversationSummaryList(results, debugLabel: 'parse_search');
+    }
+    return [];
   }
 
   // Debug method to test API endpoints

lib/core/services/optimized_storage_service.dart

@@ -9,6 +9,7 @@ import '../persistence/hive_boxes.dart';
 import '../persistence/persistence_keys.dart';
 import '../utils/debug_logger.dart';
 import 'secure_credential_storage.dart';
+import 'worker_manager.dart';
 
 /// Optimized storage service backed by Hive for non-sensitive data and
 /// FlutterSecureStorage for credentials.
@@ -16,19 +17,22 @@ class OptimizedStorageService {
   OptimizedStorageService({
     required FlutterSecureStorage secureStorage,
     required HiveBoxes boxes,
+    required WorkerManager workerManager,
   }) : _preferencesBox = boxes.preferences,
        _cachesBox = boxes.caches,
        _attachmentQueueBox = boxes.attachmentQueue,
        _metadataBox = boxes.metadata,
        _secureCredentialStorage = SecureCredentialStorage(
          instance: secureStorage,
-       );
+       ),
+       _workerManager = workerManager;
 
   final Box<dynamic> _preferencesBox;
   final Box<dynamic> _cachesBox;
   final Box<dynamic> _attachmentQueueBox;
   final Box<dynamic> _metadataBox;
   final SecureCredentialStorage _secureCredentialStorage;
+  final WorkerManager _workerManager;
 
   static const String _authTokenKey = 'auth_token_v3';
   static const String _activeServerIdKey = PreferenceKeys.activeServerId;
@@ -298,19 +302,13 @@ class OptimizedStorageService {
       if (stored == null) {
         return const [];
       }
-      if (stored is String) {
-        final decoded = jsonDecode(stored) as List<dynamic>;
-        return decoded.map((item) => Conversation.fromJson(item)).toList();
-      }
-      if (stored is List) {
-        return stored
-            .map(
-              (item) =>
-                  Conversation.fromJson(Map<String, dynamic>.from(item as Map)),
-            )
-            .toList();
-      }
-      return const [];
+      final parsed = await _workerManager
+          .schedule<Map<String, dynamic>, List<Map<String, dynamic>>>(
+            _decodeStoredConversationsWorker,
+            {'stored': stored},
+            debugLabel: 'decode_local_conversations',
+          );
+      return parsed.map(Conversation.fromJson).toList(growable: false);
     } catch (error, stack) {
       DebugLogger.error(
         'Failed to retrieve local conversations',
@@ -455,3 +453,28 @@ class OptimizedStorageService {
     };
   }
 }
+
+List<Map<String, dynamic>> _decodeStoredConversationsWorker(
+  Map<String, dynamic> payload,
+) {
+  final stored = payload['stored'];
+  if (stored is String) {
+    final decoded = jsonDecode(stored);
+    if (decoded is List) {
+      return decoded
+          .whereType<Map>()
+          .map((item) => Map<String, dynamic>.from(item))
+          .toList();
+    }
+    return <Map<String, dynamic>>[];
+  }
+
+  if (stored is List) {
+    return stored
+        .whereType<Map>()
+        .map((item) => Map<String, dynamic>.from(item))
+        .toList();
+  }
+
+  return <Map<String, dynamic>>[];
+}

lib/core/services/worker_manager.dart

@@ -170,12 +170,14 @@ class WorkerManager {
 
 /// Keep a single [WorkerManager] alive across the app.
 @Riverpod(keepAlive: true)
-// ignore: functional_ref
-WorkerManager workerManager(Ref ref) {
-  final concurrency = kIsWeb ? 1 : WorkerManager._defaultMaxConcurrentTasks;
-  final manager = WorkerManager(maxConcurrentTasks: concurrency);
-  ref.onDispose(manager.dispose);
-  return manager;
+class WorkerManagerNotifier extends _$WorkerManagerNotifier {
+  @override
+  WorkerManager build() {
+    final concurrency = kIsWeb ? 1 : WorkerManager._defaultMaxConcurrentTasks;
+    final manager = WorkerManager(maxConcurrentTasks: concurrency);
+    ref.onDispose(manager.dispose);
+    return manager;
+  }
 }
 
 class _EnqueuedJob {