/android-persistence

name: android-persistence
description: Implement Room schemas and DataStore preferences with proper async patterns in Android. Use when the primary task is storage schema, DAO, migration, or preference isolation; defer auth-token/security storage, any CoroutineWorker/WorkManager task, Hilt graph wiring, and cache-policy design.
metadata:
  triggers:
    files:
    - '**/*Dao.kt'
    - '**/*Database.kt'
    - '**/*Entity.kt'
    keywords:
    - "@Dao"
    - "@Entity"
    - RoomDatabase

Android Persistence Standards

**Priority: P0 (CRITICAL)**

1. Configure Room Database

• Return `Flow<List<T>>` for queries, use `suspend` for Write/Insert.
• Keep `@Entity` data classes simple. Map to Domain models in Repository.
• Use `@Transaction` for multi-table queries (Relations).

See [DAO templates](references/implementation.md) for Room DAO patterns.

2. Migrate to DataStore

• Replace `SharedPreferences` with `ProtoDataStore` (type-safe) or `PreferencesDataStore`.
• Inject singleton DataStore instance via Hilt.

See [DAO templates](references/implementation.md) for DataStore migration patterns.

Anti-Patterns

• **No IO on Main Thread**: Room handles dispatchers, but verify Flow collected off-main.
• **No @Entity in UI Layer**: Map to Domain or UI models in Repository.

References

• [DAO Templates](references/implementation.md)