code-review-flutterdart

name	Code Review (Flutter/Dart)
description	Comprehensive guidelines for reviewing Flutter code in the YouDown project, focusing on Bloc, performance, and best practices.

Code Review Guidelines for YouDown Mobile

Use this skill when asked to review code or before finalizing significant changes. Focus on the following areas to ensure high quality, stability, and maintainability.

1. Architecture & State Management (BLoC)

• Event/State Immutability: Ensure all Bloc Events and States are immutable (@immutable or using Freezed).
• Logic Separation: UI widgets should only dispatch events and listen to states. Business logic must reside in Blocs or Repositories.
• Bloc Usage:
  • Use BlocBuilder for rebuilding UI part.
  • Use BlocListener for side effects (navigation, toasts, dialogs).
  • Avoid overly complex logic inside build() methods.
• HydratedBloc: Verify that state persistence logic (fromJson/toJson) handles nulls and data migration gracefully.

2. Resource Management & Performance

• Disposal: Check that all Controllers (VideoPlayer, Chewie, TextEditing, Animation), Timers, and Streams are properly disposed in dispose().
• Media Players: Ensure video_player and just_audio instances are stopped/paused before disposal to prevent background audio leaks.
• Build Method: Avoid expensive computations or object instantiations inside build(). Use late final or initState where appropriate.
• const Constructors: Use const for widgets and values wherever possible to optimize rebuilds.

3. Error Handling & Stability

• Network Requests: All Dio requests must be wrapped in try/catch blocks handling DioException.
• FFmpeg: Check for FFmpeg session return codes. Handle cases where merging or conversion fails.
• Permissions: Verify that permission requests (manageExternalStorage, photos, etc.) check the Android SDK version correctly (SDK 30+ vs older).
• Null Safety: strictly avoid force unwrapping (!) unless absolutely certain. Use ?. and ?? defaults.

4. User Interface & UX

• Material 3: Ensure components follow Material 3 design guidelines (use ColorScheme, proper typography).
• Responsiveness: UI should handle different screen sizes and orientations gracefully.
• Dark Mode: Verify correct color usage for both Light and Dark themes (use Theme.of(context).colorScheme).
• Localization: All user-facing text must use easy_localization keys (e.g., "key".tr()). No hardcoded strings.

5. Specific Project patterns

• Background Service: Ensure tasks intended for background execution properly communicate with FlutterForegroundTask.
• Navigation: Use GoRouter for all navigation. Avoid Navigator.push unless working with dialogs/overlays that require it.

6. Security

• Input Validation: Validate all user inputs (especially YouTube URLs).
• File System: Be careful with file path manipulations. Use path_provider and validate paths before writing.