Flutter dev
Flutter cross-platform development guide covering widget patterns, Riverpod/Bloc state management, GoRouter navigation, performance optimization, and platform-specific implementations. Includes const optimization, responsive layouts, testing strategies, and DevTools profiling. Use when: building Flutter apps, implementing state management (Riverpod/Bloc), setting up GoRouter navigation, creating custom widgets, optimizing performance, writing widget tests, cross-platform development.From its SKILL.md
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SKILL.md
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Flutter Development Guide
A practical guide for building cross-platform applications with Flutter 3 and Dart. Focuses on proven patterns, state management, and performance optimization.
Quick Reference
Widget Patterns
| Purpose | Component |
|---|---|
| State management (simple) | StateProvider + ConsumerWidget |
| State management (complex) | NotifierProvider / Bloc |
| Async data | FutureProvider / AsyncNotifierProvider |
| Real-time streams | StreamProvider |
| Navigation | GoRouter + context.go/push |
| Responsive layout | LayoutBuilder + breakpoints |
| List display | ListView.builder |
| Complex scrolling | CustomScrollView + Slivers |
| Hooks | HookWidget + useState/useEffect |
| Forms | Form + TextFormField + validation |
Performance Patterns
| Purpose | Solution |
|---|---|
| Prevent rebuilds | const constructors |
| Selective updates | ref.watch(provider.select(...)) |
| Isolate repaints | RepaintBoundary |
| Lazy lists | ListView.builder |
| Heavy computation | compute() isolate |
| Image caching | cached_network_image |
Core Principles
Widget Optimization
- Use
constconstructors wherever possible - Extract static widgets to separate const classes
- Use
Keyfor list items (ValueKey, ObjectKey) - Prefer
ConsumerWidgetoverStatefulWidgetfor state
State Management
- Riverpod for dependency injection and simple state
- Bloc/Cubit for event-driven workflows and complex logic
- Never mutate state directly (create new instances)
- Use
select()to minimize rebuilds
Layout
- 8pt spacing increments (8, 16, 24, 32, 48)
- Responsive breakpoints: mobile (<650), tablet (650-1100), desktop (>1100)
- Support all screen sizes with flexible layouts
- Follow Material 3 / Cupertino design guidelines
Performance
- Profile with DevTools before optimizing
- Target <16ms frame time for 60fps
- Use
RepaintBoundaryfor complex animations - Offload heavy work with
compute()
Checklist
Widget Best Practices
-
constconstructors on all static widgets - Proper
Keyon list items -
ConsumerWidgetfor state-dependent widgets - No widget building inside
build()method - Extract reusable widgets to separate files
State Management
- Immutable state objects
-
select()for granular rebuilds - Proper provider scoping
- Dispose controllers and subscriptions
- Handle loading/error states
Navigation
- GoRouter with typed routes
- Auth guards via redirect
- Deep linking support
- State preservation across routes
Performance
- Profile mode testing (
flutter run --profile) - <16ms frame rendering time
- No unnecessary rebuilds (DevTools check)
- Images cached and resized
- Heavy computation in isolates
Testing
- Widget tests for UI components
- Unit tests for business logic
- Integration tests for user flows
- Bloc tests with
blocTest()
References
| Topic | Reference |
|---|---|
| Widget patterns, const optimization, responsive layout | Widget Patterns |
| Riverpod providers, notifiers, async state | Riverpod State Management |
| Bloc, Cubit, event-driven state | Bloc State Management |
| GoRouter setup, routes, deep linking | GoRouter Navigation |
| Feature-based structure, dependencies | Project Structure |
| Profiling, const optimization, DevTools | Performance Optimization |
| Widget tests, integration tests, mocking | Testing Strategies |
| iOS/Android/Web specific implementations | Platform Integration |
| Implicit/explicit animations, Hero, transitions | Animations |
| Dio, interceptors, error handling, caching | Networking |
| Form validation, FormField, input formatters | Forms |
| i18n, flutter_localizations, intl | Localization |
Flutter, Dart, Material Design, and Cupertino are trademarks of Google LLC and Apple Inc. respectively. Riverpod, Bloc, and GoRouter are open-source packages by their respective maintainers.
What ships with it: 12 files
110.4 KB alongside SKILL.md
references/
- animations.md12.6 KB
- bloc-state.md6.6 KB
- forms.md17.0 KB
- gorouter-navigation.md6.1 KB
- localization.md11.7 KB
- networking.md13.6 KB
- performance.md6.5 KB
- platform-specific.md10.8 KB
- project-structure.md6.6 KB
- riverpod-state.md5.3 KB
- testing.md8.4 KB
- widget-patterns.md5.1 KB
Gives 0 of the 12 instructions most test skills give in ~1.0k tokens
Counted across 1,201 of the 2,096 authors here whose files we hold, read 2026-09-06
- Write a failing test before writing codein 43 of 1201, across 36 files
- Run the full test suitein 36 of 1201, across 35 files
- Test only one variable per experimentin 34 of 1201, across 17 files
- Read product marketing context before asking questionsin 34 of 1201, across 14 files
- Mock external dependenciesin 34 of 1201, across 30 files
- Define primary, secondary, and guardrail metricsin 33 of 1201, across 16 files
- Pre-determine sample size before startingin 31 of 1201, across 14 files
- Test behavior rather than implementationin 31 of 1201, across 29 files
- Formulate a hypothesis before designing a testin 30 of 1201, across 13 files
- Document every test hypothesis, variant, and resultin 29 of 1201, across 11 files
- Use descriptive test function namesin 25 of 1201, across 21 files
- Commit to the methodology without stopping earlyin 24 of 1201, across 8 files
Grouped from the skills themselves: near-identical wordings counted once, and counted by distinct author, so one author publishing three of these counts once. Length counted with cl100k_base; the agent that loads this file may tokenize it differently.