Production-ready Dart and Flutter patterns covering null safety, immutable state, async composition, widget architecture, popular state management frameworks (BLoC, Riverpod, Provider), GoRouter navigation, Dio networking, Freezed code generation, and clean architecture. Use when writing or reviewin

Dart/Flutter Patterns When to Use Use this skill when: Starting a new Flutter feature and need idiomatic patterns for state management, navigation, or data access Reviewing or writing Dart code and need guidance on null safety, sealed types, or async composition Setting up a new Flutter project and choosing between BLoC, Riverpod, or Provider Implementing secure HTTP clients, WebView integration, or local storage Writing tests for Flutter widgets, Cubits, or Riverpod providers Wiring up GoRouter with authentication guards How It Works This skill provides copy paste ready Dart/Flutter code patterns organized by concern: 1. Null safety — avoid ! , prefer ?. / ?? /pattern matching 2. Immutable state — sealed classes, freezed , copyWith 3. Async composition — concurrent Future.wait , safe BuildContext after await 4. Widget architecture — extract to classes (not methods), const propagation, scoped rebuilds 5. State management — BLoC/Cubit events, Riverpod notifiers and derived providers 6. Navigation — GoRouter with reactive auth guards via refreshListenable 7. Networking — Dio with interceptors, token refresh with one time retry guard 8. Error handling — global capture, ErrorWidget.builder , crashlytics wiring 9. Testing — unit (BLoC test), widget (ProviderScope overrides), fakes over mocks Examples Practical, production ready patterns for Dart and Flutter applications. Library agnostic where possible, with explicit coverage of the most common ecosystem packages. 1. Null Safety Fundamentals Prefer Patterns Over Bang Operator Avoid late Overuse 2. Immutable State Sealed Classes for State Hierarchies Freezed for Boilerplate Free Immutability 3. Async Composition Structured Concurrency with Future.wait Stream Patterns BuildContext After Await 4. Widget Architecture Extract to Classes, Not Methods const Propagation Scoped Rebuilds 5. State Management: BLoC/Cubit 6. State Management: Riverpod 7. Navigation with GoRouter 8. HTTP with Dio 9. Error Handling Architecture 10. Testing Quick Reference References [Effective Dart: Design](https://dart.dev/effective dart/design) [Flutter Performance Best Practices](https://docs.flutter.dev/perf/best practices) [Riverpod Documentation](https://riverpod.dev/) [BLoC Library](https://bloclibrary.dev/) [GoRouter](https://pub.dev/packages/go router) [Freezed](https://pub.dev/packages/freezed) Skill: flutter dart code review — comprehensive review checklist Rules: rules/dart/ — coding style, patterns, security, testing, hooks

dart-flutter-patterns