diff --git a/lib/core/models/folder.dart b/lib/core/models/folder.dart
index 6ddd66a..c4ac6f6 100644
--- a/lib/core/models/folder.dart
+++ b/lib/core/models/folder.dart
@@ -19,25 +19,38 @@ sealed class Folder with _$Folder {
   }) = _Folder;
 
   factory Folder.fromJson(Map<String, dynamic> json) {
-    // Extract conversation IDs from items.chats if available
-    final items = json['items'] as Map<String, dynamic>?;
-    final chats = items?['chats'] as List?;
+    List<String> extractConversationIds(dynamic source) {
+      if (source is! List) {
+        return const <String>[];
+      }
+      final ids = <String>[];
+      for (final entry in source) {
+        String value = '';
+        if (entry is String) {
+          value = entry;
+        } else if (entry is Map<String, dynamic>) {
+          final id = entry['id'];
+          if (id is String) {
+            value = id;
+          } else if (id != null) {
+            value = id.toString();
+          }
+        } else if (entry != null) {
+          value = entry.toString();
+        }
 
-    // Handle both string IDs and conversation objects
-    final conversationIds =
-        chats
-            ?.map((chat) {
-              if (chat is String) {
-                return chat;
-              } else if (chat is Map<String, dynamic>) {
-                return chat['id'] as String? ?? '';
-              }
-              return '';
-            })
-            .where((id) => id.isNotEmpty)
-            .toList()
-            .cast<String>() ??
-        <String>[];
+        if (value.isNotEmpty) {
+          ids.add(value);
+        }
+      }
+      return ids;
+    }
+
+    final items = json['items'] as Map<String, dynamic>?;
+    final chats = items?['chats'];
+    final explicitIds = extractConversationIds(json['conversation_ids']);
+    final implicitIds = extractConversationIds(chats);
+    final conversationIds = explicitIds.isNotEmpty ? explicitIds : implicitIds;
 
     // Handle Unix timestamp conversion
     DateTime? parseTimestamp(dynamic timestamp) {
@@ -67,3 +80,29 @@ sealed class Folder with _$Folder {
     );
   }
 }
+
+extension FolderJsonExtension on Folder {
+  Map<String, dynamic> toJson() {
+    Map<String, dynamic>? normalizedItems;
+    if (items != null) {
+      normalizedItems = Map<String, dynamic>.from(items!);
+    } else if (conversationIds.isNotEmpty) {
+      normalizedItems = {'chats': List<String>.from(conversationIds)};
+    }
+
+    return {
+      'id': id,
+      'name': name,
+      if (parentId != null) 'parent_id': parentId,
+      if (userId != null) 'user_id': userId,
+      if (createdAt != null) 'created_at': createdAt!.toIso8601String(),
+      if (updatedAt != null) 'updated_at': updatedAt!.toIso8601String(),
+      'is_expanded': isExpanded,
+      if (normalizedItems != null) 'items': normalizedItems,
+      if (meta != null) 'meta': Map<String, dynamic>.from(meta!),
+      if (data != null) 'data': Map<String, dynamic>.from(data!),
+      if (conversationIds.isNotEmpty)
+        'conversation_ids': List<String>.from(conversationIds),
+    };
+  }
+}
diff --git a/lib/core/persistence/hive_boxes.dart b/lib/core/persistence/hive_boxes.dart
index 28b461f..ceb821b 100644
--- a/lib/core/persistence/hive_boxes.dart
+++ b/lib/core/persistence/hive_boxes.dart
@@ -15,6 +15,7 @@ final class HiveStoreKeys {
 
   // Cache entries
   static const String localConversations = 'local_conversations';
+  static const String localFolders = 'local_folders';
   static const String attachmentQueueEntries = 'attachment_queue_entries';
   static const String taskQueue = 'outbound_task_queue_v1';
 }
diff --git a/lib/core/persistence/persistence_migrator.dart b/lib/core/persistence/persistence_migrator.dart
index d6a278c..d0f3946 100644
--- a/lib/core/persistence/persistence_migrator.dart
+++ b/lib/core/persistence/persistence_migrator.dart
@@ -107,7 +107,24 @@ class PersistenceMigrator {
   }
 
   Future<void> _migrateCaches(SharedPreferences prefs) async {
-    final jsonString = prefs.getString(HiveStoreKeys.localConversations);
+    await _migrateJsonListCache(
+      prefs,
+      HiveStoreKeys.localConversations,
+      logLabel: 'local conversations',
+    );
+    await _migrateJsonListCache(
+      prefs,
+      HiveStoreKeys.localFolders,
+      logLabel: 'local folders',
+    );
+  }
+
+  Future<void> _migrateJsonListCache(
+    SharedPreferences prefs,
+    String key, {
+    required String logLabel,
+  }) async {
+    final jsonString = prefs.getString(key);
     if (jsonString == null || jsonString.isEmpty) {
       return;
     }
@@ -118,11 +135,11 @@ class PersistenceMigrator {
         final list = decoded
             .map((entry) => Map<String, dynamic>.from(entry as Map))
             .toList(growable: false);
-        await _boxes.caches.put(HiveStoreKeys.localConversations, list);
+        await _boxes.caches.put(key, list);
       }
     } catch (error, stack) {
       DebugLogger.error(
-        'Failed to migrate local conversations',
+        'Failed to migrate $logLabel',
         scope: 'persistence/migration',
         error: error,
         stackTrace: stack,
@@ -206,6 +223,7 @@ class PersistenceMigrator {
       PreferenceKeys.onboardingSeen,
       PreferenceKeys.reviewerMode,
       HiveStoreKeys.localConversations,
+      HiveStoreKeys.localFolders,
       HiveStoreKeys.attachmentQueueEntries,
       LegacyPreferenceKeys.attachmentUploadQueue,
       LegacyPreferenceKeys.taskQueue,
diff --git a/lib/core/providers/app_providers.dart b/lib/core/providers/app_providers.dart
index ca03ecb..c39dfb6 100644
--- a/lib/core/providers/app_providers.dart
+++ b/lib/core/providers/app_providers.dart
@@ -1801,24 +1801,53 @@ class Folders extends _$Folders {
   Future<List<Folder>> build() async {
     if (!ref.watch(isAuthenticatedProvider2)) {
       DebugLogger.log('skip-unauthed', scope: 'folders');
+      _persistFoldersAsync(const []);
       return const [];
     }
+
+    final storage = ref.watch(optimizedStorageServiceProvider);
+    final cached = await storage.getLocalFolders();
+    if (cached.isNotEmpty) {
+      DebugLogger.log(
+        'cache-restored',
+        scope: 'folders/cache',
+        data: {'count': cached.length},
+      );
+      Future.microtask(() async {
+        try {
+          await refresh();
+        } catch (error, stackTrace) {
+          DebugLogger.error(
+            'warm-refresh-failed',
+            scope: 'folders/cache',
+            error: error,
+            stackTrace: stackTrace,
+          );
+        }
+      });
+      return _sort(cached);
+    }
+
+    DebugLogger.log('cache-empty', scope: 'folders/cache');
     final api = ref.watch(apiServiceProvider);
     if (api == null) {
       DebugLogger.warning('api-missing', scope: 'folders');
       return const [];
     }
-    return _load(api);
+    final fresh = await _load(api);
+    return fresh;
   }
 
   Future<void> refresh() async {
     if (!ref.read(isAuthenticatedProvider2)) {
       state = const AsyncData<List<Folder>>([]);
+      _persistFoldersAsync(const []);
       return;
     }
     final api = ref.read(apiServiceProvider);
     if (api == null) {
       state = const AsyncData<List<Folder>>([]);
+      _persistFoldersAsync(const []);
       return;
     }
     final result = await AsyncValue.guard(() => _load(api));
@@ -1835,7 +1864,9 @@ class Folders extends _$Folders {
     } else {
       updated.add(folder);
     }
-    state = AsyncData<List<Folder>>(_sort(updated));
+    final sorted = _sort(updated);
+    state = AsyncData<List<Folder>>(sorted);
+    _persistFoldersAsync(sorted);
   }
 
   void updateFolder(String id, Folder Function(Folder folder) transform) {
@@ -1845,7 +1876,9 @@ class Folders extends _$Folders {
     if (index < 0) return;
     final updated = <Folder>[...current];
     updated[index] = transform(updated[index]);
-    state = AsyncData<List<Folder>>(_sort(updated));
+    final sorted = _sort(updated);
+    state = AsyncData<List<Folder>>(sorted);
+    _persistFoldersAsync(sorted);
   }
 
   void removeFolder(String id) {
@@ -1854,7 +1887,9 @@ class Folders extends _$Folders {
     final updated = current
         .where((folder) => folder.id != id)
         .toList(growable: true);
-    state = AsyncData<List<Folder>>(_sort(updated));
+    final sorted = _sort(updated);
+    state = AsyncData<List<Folder>>(sorted);
+    _persistFoldersAsync(sorted);
   }
 
   Future<List<Folder>> _load(ApiService api) async {
@@ -1868,7 +1903,9 @@ class Folders extends _$Folders {
         scope: 'folders',
         data: {'count': folders.length},
       );
-      return _sort(folders);
+      final sorted = _sort(folders);
+      _persistFoldersAsync(sorted);
+      return sorted;
     } catch (e, stackTrace) {
       DebugLogger.error(
         'fetch-failed',
@@ -1880,6 +1917,11 @@ class Folders extends _$Folders {
     }
   }
 
+  void _persistFoldersAsync(List<Folder> folders) {
+    final storage = ref.read(optimizedStorageServiceProvider);
+    unawaited(storage.saveLocalFolders(folders));
+  }
+
   List<Folder> _sort(List<Folder> input) {
     final sorted = [...input];
     sorted.sort((a, b) => a.name.toLowerCase().compareTo(b.name.toLowerCase()));
diff --git a/lib/core/services/optimized_storage_service.dart b/lib/core/services/optimized_storage_service.dart
index 9b44b5a..bfb3fd1 100644
--- a/lib/core/services/optimized_storage_service.dart
+++ b/lib/core/services/optimized_storage_service.dart
@@ -4,6 +4,7 @@ import 'package:flutter_secure_storage/flutter_secure_storage.dart';
 import 'package:hive_ce/hive.dart';
 
 import '../models/conversation.dart';
+import '../models/folder.dart';
 import '../models/server_config.dart';
 import '../persistence/hive_boxes.dart';
 import '../persistence/persistence_keys.dart';
@@ -40,6 +41,7 @@ class OptimizedStorageService {
   static const String _themePaletteKey = PreferenceKeys.themePalette;
   static const String _localeCodeKey = PreferenceKeys.localeCode;
   static const String _localConversationsKey = HiveStoreKeys.localConversations;
+  static const String _localFoldersKey = HiveStoreKeys.localFolders;
   static const String _onboardingSeenKey = PreferenceKeys.onboardingSeen;
   static const String _reviewerModeKey = PreferenceKeys.reviewerMode;
 
@@ -304,7 +306,7 @@ class OptimizedStorageService {
       }
       final parsed = await _workerManager
           .schedule<Map<String, dynamic>, List<Map<String, dynamic>>>(
-            _decodeStoredConversationsWorker,
+            _decodeStoredJsonListWorker,
             {'stored': stored},
             debugLabel: 'decode_local_conversations',
           );
@@ -326,8 +328,8 @@ class OptimizedStorageService {
           .map((conversation) => conversation.toJson())
           .toList();
       final serialized = await _workerManager
-          .schedule<Map<String, dynamic>, String>(_encodeConversationsWorker, {
-            'conversations': jsonReady,
+          .schedule<Map<String, dynamic>, String>(_encodeJsonListWorker, {
+            'items': jsonReady,
           }, debugLabel: 'encode_local_conversations');
       await _cachesBox.put(_localConversationsKey, serialized);
       DebugLogger.log(
@@ -344,6 +346,52 @@ class OptimizedStorageService {
     }
   }
 
+  Future<List<Folder>> getLocalFolders() async {
+    try {
+      final stored = _cachesBox.get(_localFoldersKey);
+      if (stored == null) {
+        return const [];
+      }
+      final parsed = await _workerManager
+          .schedule<Map<String, dynamic>, List<Map<String, dynamic>>>(
+            _decodeStoredJsonListWorker,
+            {'stored': stored},
+            debugLabel: 'decode_local_folders',
+          );
+      return parsed.map(Folder.fromJson).toList(growable: false);
+    } catch (error, stack) {
+      DebugLogger.error(
+        'Failed to retrieve local folders',
+        scope: 'storage/optimized',
+        error: error,
+        stackTrace: stack,
+      );
+      return const [];
+    }
+  }
+
+  Future<void> saveLocalFolders(List<Folder> folders) async {
+    try {
+      final jsonReady = folders.map((folder) => folder.toJson()).toList();
+      final serialized = await _workerManager
+          .schedule<Map<String, dynamic>, String>(_encodeJsonListWorker, {
+            'items': jsonReady,
+          }, debugLabel: 'encode_local_folders');
+      await _cachesBox.put(_localFoldersKey, serialized);
+      DebugLogger.log(
+        'Saved ${folders.length} local folders',
+        scope: 'storage/optimized',
+      );
+    } catch (error, stack) {
+      DebugLogger.error(
+        'Failed to save local folders',
+        scope: 'storage/optimized',
+        error: error,
+        stackTrace: stack,
+      );
+    }
+  }
+
   // ---------------------------------------------------------------------------
   // Batch operations
   // ---------------------------------------------------------------------------
@@ -458,7 +506,7 @@ class OptimizedStorageService {
   }
 }
 
-List<Map<String, dynamic>> _decodeStoredConversationsWorker(
+List<Map<String, dynamic>> _decodeStoredJsonListWorker(
   Map<String, dynamic> payload,
 ) {
   final stored = payload['stored'];
@@ -483,8 +531,8 @@ List<Map<String, dynamic>> _decodeStoredConversationsWorker(
   return <Map<String, dynamic>>[];
 }
 
-String _encodeConversationsWorker(Map<String, dynamic> payload) {
-  final raw = payload['conversations'];
+String _encodeJsonListWorker(Map<String, dynamic> payload) {
+  final raw = payload['items'] ?? payload['conversations'];
   if (raw is List) {
     return jsonEncode(raw);
   }