# Android Persistence

> 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.

- Skill: `hoangnguyen0403/android-persistence` (Agent Skill, multi-file: 3 files)
- Install (CLI): `npx skillmds@latest add hoangnguyen0403/android-persistence`
- Raw SKILL.md: https://api.skillmd.com/api/skills/hoangnguyen0403/android-persistence/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Security
- Author: HoangNguyen0403 (https://skillmd.com/u/hoangnguyen0403)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/hoangnguyen0403/android-persistence

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# 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)