# Architecture

> MVVM pattern, Clean Architecture, Repository pattern, dependency injection, SOLID principles.

- Skill: `pluginagentmarketplace/architecture` (Agent Skill, multi-file: 12 files)
- Install (CLI): `npx skillmds@latest add pluginagentmarketplace/architecture`
- Raw SKILL.md: https://api.skillmd.com/api/skills/pluginagentmarketplace/architecture/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: pluginagentmarketplace (https://skillmd.com/u/pluginagentmarketplace)
- Updated: 2026-09-10
- Page: https://skillmd.com/skills/pluginagentmarketplace/architecture

---


# App Architecture Skill

## Quick Start

### MVVM Pattern
```kotlin
@HiltViewModel
class UserViewModel @Inject constructor(
    private val repository: UserRepository
) : ViewModel() {
    private val _state = MutableLiveData<UiState>()
    val state: LiveData<UiState> = _state
    
    fun loadUser(id: Int) {
        viewModelScope.launch {
            _state.value = repository.getUser(id)
        }
    }
}
```

### Repository Pattern
```kotlin
interface UserRepository {
    suspend fun getUser(id: Int): User
}

class UserRepositoryImpl(
    private val dao: UserDao,
    private val api: UserApi
) : UserRepository {
    override suspend fun getUser(id: Int): User {
        return dao.getUser(id) ?: api.fetchUser(id)
    }
}
```

### Dependency Injection (Hilt)
```kotlin
@Module
@InstallIn(SingletonComponent::class)
object RepositoryModule {
    @Provides
    fun provideUserRepository(dao: UserDao, api: UserApi): UserRepository {
        return UserRepositoryImpl(dao, api)
    }
}
```

## Key Concepts

### MVVM Benefits
- Lifecycle awareness
- Configuration change handling
- Separation of concerns
- Testability

### Clean Architecture Layers
- Domain: Business rules
- Application: Use cases
- Presentation: UI
- Infrastructure: Data sources

### SOLID Principles
- S: Single Responsibility
- O: Open/Closed
- L: Liskov Substitution
- I: Interface Segregation
- D: Dependency Inversion

## Best Practices

✅ Dependency injection
✅ Interface-based design
✅ Layered architecture
✅ Single responsibility
✅ Testable code

## Resources

- [Architecture Guide](https://developer.android.com/jetpack/guide)
- [SOLID Principles](https://en.wikipedia.org/wiki/SOLID)
- [Hilt Documentation](https://developer.android.com/training/dependency-injection/hilt-android)