# Android Persistence

> Standards for Room Database and DataStore

- Skill: `majiayu000/android-persistence` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds add majiayu000/android-persistence`
- Raw SKILL.md: https://api.skillmd.com/api/skills/majiayu000/android-persistence/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: majiayu000 (https://skillmd.com/u/majiayu000)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/majiayu000/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

- **Main Thread**: `**No IO on Main**: Use Dispatchers.IO (Room helper does this, but verify flow collection).`
- **Domain Leak**: `**No Entities in UI**: Map to Domain/UI Models.`

## References

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