Dev Flutter

---
name: dev-flutter
description: Flutter development with Clean Architecture and BLoC. Trigger when the user wants to create widgets, screens, or Flutter features.
allowed-tools:
  - Read
  - Write
  - Edit
  - Bash
  - Glob
  - Grep
context: fork
argument-hint: "[widget-or-screen]"
---

# Flutter Development

## Architecture

```
/lib/features/[feature]
├── /data
│   ├── /datasources      # API, local storage
│   ├── /models           # JSON serialization
│   └── /repositories     # Implementation
├── /domain
│   ├── /entities         # Business objects
│   ├── /repositories     # Interfaces
│   └── /usecases         # Business logic
└── /presentation
    ├── /bloc             # State management
    ├── /pages            # Screens
    └── /widgets          # UI components
```

## BLoC Pattern

```dart
// Events
abstract class AuthEvent {}
class LoginRequested extends AuthEvent {
  final String email, password;
  LoginRequested(this.email, this.password);
}

// States
abstract class AuthState {}
class AuthInitial extends AuthState {}
class AuthLoading extends AuthState {}
class AuthSuccess extends AuthState { final User user; }
class AuthFailure extends AuthState { final String error; }

// BLoC
class AuthBloc extends Bloc<AuthEvent, AuthState> {
  AuthBloc(): super(AuthInitial()) {
    on<LoginRequested>(_onLogin);
  }
}
```

## Widgets

- Stateless for pure UI
- Stateful only if local state is needed
- const constructors when possible
- Composition over inheritance

## Tests

```dart
// Widget test
testWidgets('shows button', (tester) async {
  await tester.pumpWidget(MaterialApp(home: MyWidget()));
  expect(find.byType(ElevatedButton), findsOneWidget);
});

// BLoC test
blocTest<AuthBloc, AuthState>(
  'emits [Loading, Success] on login',
  build: () => AuthBloc(),
  act: (bloc) => bloc.add(LoginRequested('email', 'pass')),
  expect: () => [AuthLoading(), isA<AuthSuccess>()],
);
```