# Flutter Feature Implementation

> Use when implementing a Flutter feature from scratch or completing one in progress. Covers file structure, design system compliance, state management setup, error handling, testing, and build_runner requirements.

- Skill: `tomevault-io/flutter-feature-implementation` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add tomevault-io/flutter-feature-implementation`
- Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/flutter-feature-implementation/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Design & Media
- Author: tomevault-io (https://skillmd.com/u/tomevault-io)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/tomevault-io/flutter-feature-implementation

---


# Feature Implementation Skill

## Checklist

### Code Structure
- [ ] Files in data/domain/view (DTOs → data, Models → domain)
- [ ] @JsonSerializable on DTOs, Equatable on Models
- [ ] Repository interface in domain, implementation in data
- [ ] Bloc (complex) or Cubit (simple) in view

### Design System
- [ ] ColorPalette (no hardcoded colors)
- [ ] Spacing (no magic numbers)
- [ ] Project's Design System Text Widgets (typography)
- [ ] Project's Design System Assets (images/icons)
- [ ] Core widgets (`lib/core/widgets/`)

### State Management
- [ ] Bloc for complex (multiple events), Cubit for simple
- [ ] @injectable on classes (auto-registration)
- [ ] BlocProvider at page level
- [ ] BlocBuilder scoped to minimal subtree

### Error Handling
- [ ] Try-catch in repositories
- [ ] Map DioException → custom exceptions (NetworkException, NotFoundException)
- [ ] Error states in Bloc/Cubit
- [ ] User-friendly messages

### Testing
- [ ] Unit tests for Bloc/Cubit (90%+ target)
- [ ] Mock with mocktail
- [ ] Test structure mirrors source
- [ ] Use fixtures for mock data

### Quality
- [ ] `flutter analyze` passes (zero errors)
- [ ] Run `./build_runner.sh` after changes
- [ ] Commit *.g.dart files

## Patterns

```dart
// ✅ Clear naming
class FeatureRepository {}

// ✅ Null safety
final name = user?.name ?? 'Guest';

// ✅ const
const Text('Static');

// ✅ Async/await
try {
  final data = await repository.fetch();
  emit(LoadedState(data));
} catch (e) {
  emit(ErrorState(e.toString()));
}

// ✅ Bloc test
blocTest<MyBloc, MyState>(
  'emits [Loading, Loaded]',
  build: () {
    when(() => repository.fetch()).thenAnswer((_) async => data);
    return bloc;
  },
  act: (bloc) => bloc.add(LoadRequested()),
  expect: () => [LoadingState(), LoadedState(data)],
);
```

## Resources
- Extensions → `lib/core/utils/extensions/`
- Helpers → `lib/core/utils/helpers/`
- Validators → `lib/core/utils/validators/`

---
> Source: [Desquared/agents-rules-skills](https://github.com/Desquared/agents-rules-skills) — distributed by [TomeVault](https://tomevault.io).
<!-- tomevault:4.0:skill_md:2026-06-16 -->