feature-modules

Feature Modules Architecture — flutter_core_modules

Each feature under lib/src/features/<feature>/ follows the same three-layer clean architecture. This skill documents the exact pattern so new features are consistent.

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1. Directory Layout

Every feature follows this structure:

lib/src/features/<feature>/
├── domain/
│   ├── repositories/
│   │   └── <feature>_repository.dart       # abstract contract
│   ├── data_sources/                        # (if needed)
│   │   └── <feature>_data_source.dart       # abstract contract
│   ├── entities/                            # (if needed)
│   │   └── <entity>.dart
│   ├── usecases/
│   │   └── <verb>_<noun>_usecase.dart       # one file per use case
│   └── failures/                            # (if not using core StorageFailure)
│       └── <feature>_failure.dart
├── data/
│   ├── repositories/
│   │   └── <feature>_repository.dart        # implementation + Riverpod provider
│   └── data_sources/                        # (if needed)
│       └── <concrete>_data_source.dart      # implementation + Riverpod provider
└── presentation/
    ├── notifiers/
    │   └── <noun>_state_notifier.dart       # SafeStateNotifier subclass + provider
    ├── setup/                               # (optional, for SDK init)
    │   └── <sdk>/
    │       └── <sdk>.dart
    ├── config/                              # (optional, for config helpers)
    │   └── <config>.dart
    ├── providers/                           # (optional, for derived providers)
    │   └── <thing>.dart
    └── widgets/                             # (optional, feature-specific widgets)
        └── <widget>.dart

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2. Domain Layer

2a. Repository Interface (Abstract Contract)

The domain repository defines what the feature can do, with no implementation details:

// lib/src/features/locale/domain/repositories/locale_repository.dart
abstract class LocaleRepository {
  const LocaleRepository();

  Locale? getLocale();
  Future<bool> setLocale({required Locale locale});
  Future<bool> removeLocale();
}