# Android Persistence

> Standards for Room Database and DataStore. Use when implementing Room database schemas or DataStore preferences in Android. (triggers: **/*Dao.kt, **/*Database.kt, **/*Entity.kt, @Dao, @Entity, RoomDatabase)

- Skill: `comeonoliver/android-persistence` (Agent Skill)
- Install (CLI): `npx skillmds@latest add comeonoliver/android-persistence`
- Raw SKILL.md: https://api.skillmd.com/api/skills/comeonoliver/android-persistence/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: AI & ML
- Author: ComeOnOliver (https://skillmd.com/u/comeonoliver)
- Updated: 2026-09-08
- Page: https://skillmd.com/skills/comeonoliver/android-persistence

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# Android Persistence Standards

## **Priority: P0**

## Implementation Guidelines

### Room

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

### DataStore

- **Usage**: Replace `SharedPreferences` with `ProtoDataStore` (Type-safe) or `PreferencesDataStore`.
- **Scope**: Inject singleton instance via Hilt.

## Anti-Patterns

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

## References

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