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name: android-architecture description: Apply Clean Architecture layering, modularization, and Unidirectional Data Flow in Android projects. Use when setting up project structure, placing code in layers, configuring feature/core modules, or implementing UDF patterns; defer Compose state and ViewModel/StateFlow implementation to their specific skills. metadata: triggers: files: - "build.gradle.kts" - "settings.gradle.kts" keywords: - clean-architecture - module - layers - domain - UDF - unidirectional - feature module - core module - presentation layer - data layer

Android Architecture Standards

Priority: P0 (CRITICAL)

1. Layer Your Project (Clean Architecture)

• Domain: Pure Kotlin (No Android deps). Contains UseCases and Models.
• Data: Repository impl, DataSources (API/DB). Maps DTO -> Domain.
• UI: ViewModel + Composable. Maps Domain -> UiState.

See structure & examples for Clean Architecture layer examples.

2. Modularize by Feature and Core

• Feature Modules: :feature:home, :feature:profile.
• Core Modules: :core:ui (Design System), :core:network, :core:database.
• App Module: DI Root and Navigation Guard.

See structure & examples for module configuration.

3. Enforce Unidirectional Data Flow (UDF)

• Events: UI -> ViewModel (user actions flow UP).
• State: ViewModel -> UI (StateFlow<UiState> flows DOWN).

4. Verify Jetpack Compose Integration

• Hosting: Use setContent in Activity (No XML Layouts).
• State: Hoist state to ViewModel using collectAsStateWithLifecycle.
• Recomposition: Ensure Composable parameters @Stable or @Immutable.
• Navigation: Use Compose Navigation with Type-Safe destinations.

Anti-Patterns

• No Logic in Activity: Host Navigation only.
• No Repo in UI: Access data exclusively via ViewModel.
• No Context in Domain: Keep Logic Pure.

Verification

• Domain layer has zero Android framework imports.
• Each feature module compiles independently.
• State flows one-way: Events UP, State DOWN.
• ./gradlew build succeeds.

References

• Structure & Examples
• Jetpack Compose Best Practices