dart-flutter-patterns

Use @riverpod annotated providers for async data and Notifier classes for mutable state like a cart. Derived providers can watch other providers to compute values such as totals, and auto-dispose keeps memory usage bounded.

BLoC/Cubit suits event-driven flows with explicit state transitions and blocTest support. Riverpod offers compile-safe dependency injection and derived providers, while Provider fits simpler cases. The skill covers all three with concrete examples.

Pass a refreshListenable wrapping your auth state stream so redirects re-evaluate on login changes. In the redirect callback, check authentication state and return '/login' for unauthenticated users or null to allow navigation.

Add an InterceptorsWrapper whose onError checks for 401 responses, attempts a token refresh, and retries the request once. Mark retried requests with an extra flag like '_isRetry' to prevent infinite retry loops.

Using BuildContext after an await is unsafe because the widget may have been unmounted during the async gap. Always check the mounted property on State before calling context-dependent methods like navigation or SnackBars.

Avoid late for values that might be accessed before initialization, since it defers null errors to runtime. It is acceptable only when initialization is guaranteed first, such as an AnimationController created in initState.