Offline First Data Strategy
Session persistence, sliding-window context management, and local storage patterns for offline-capable Android apps.
AndroidOffline FirstRoomArchitecture
Why Offline First?
Users expect apps to work without connectivity. For an on-device LLM SDK, offline isn't optional — it's the core value proposition. Every design decision must assume intermittent or zero network.
Session Persistence with Room
The Offline LLM SDK stores chat sessions in SQLite via Room:
- Session metadata — ID, title, creation time, model used
- Message history — Role, content, timestamp, token count
- Automatic cleanup — Old sessions pruned based on storage limits
Sliding-Window Context Management
LLM context windows are finite. The SDK implements automatic truncation:
- Tokenize each message using the native tokenize API
- Track cumulative token count per session
- When exceeding the model's context limit, evict earliest messages
- Preserve system prompt and most recent user/assistant pairs
This prevents OOM crashes while maintaining conversational coherence.
App Lifecycle Integration
| Event | Action |
|---|---|
| App backgrounded | Cache current session state, release KV cache |
| App foregrounded | Restore session context, reload model if needed |
| Session switch | Clear KV cache, load new session history |
| Model switch | Unload current model, load new GGUF file |
Design Principles
- Local is the source of truth — Cloud sync is optional, never required
- Graceful degradation — Network features enhance but don't block core UX
- Predictable storage — Users can see and manage local data
- Background safety — State survives process death and app kills
These patterns apply beyond LLM apps — any Android app that needs reliable offline behavior benefits from the same architecture.