# 11. Background Sync & WorkManager Optimization

meta:
  id: android-production-11
  feature: android-production
  priority: P2
  depends_on: []
  tags: [performance, background, production]

objective:
- Optimize background sync using WorkManager to keep data fresh without excessive battery drain

deliverables:
- WorkManager periodic sync workers
- Battery-efficient sync strategy
- Constraint-based scheduling
- Sync status indicators

steps:
1. Audit existing sync:
   - Review android/app/.../data/sync/SyncManager.kt
   - Review OfflineWorker.kt
   - Identify sync frequency and triggers
2. Optimize sync workers:
   - Use PeriodicWorkRequest for regular sync (15 min minimum)
   - Use OneTimeWorkRequest for immediate sync
   - Set constraints: requires network, battery not low
   - Use expedited work for urgent syncs
3. Implement battery-efficient sync:
   - Batch network requests
   - Use delta sync (only changed data)
   - Respect doze mode and app standby
   - Use JobScheduler for API 21-22 (WorkManager uses internally)
4. Add sync types:
   - Alert sync: high priority, frequent
   - Exposure sync: medium priority
   - Spam database update: low priority, daily
   - Watchlist sync: on change
5. Add user controls:
   - Settings toggle for background sync
   - Sync frequency preference (if applicable)
   - Manual sync button in settings
   - Last sync timestamp display
6. Handle failures:
   - Exponential backoff for failed syncs
   - Max retry limit
   - Alert user after repeated failures
   - Queue syncs for when online
7. Add tests:
   - Test worker execution
   - Test constraint handling
   - Test battery impact

tests:
- Unit: Test worker logic
- Integration: Test WorkManager scheduling
- Battery: Verify minimal battery impact

acceptance_criteria:
- WorkManager configured for periodic sync
- Sync constraints: network available, battery not low
- Delta sync reducing data transfer
- Background sync respects doze mode
- User can enable/disable background sync
- Manual sync button in settings
- Last sync timestamp visible
- Failed syncs retry with exponential backoff
- Battery impact <5% per day from background sync
- Unit tests for all worker classes

validation:
- Enable background sync → workers scheduled
- Turn on airplane mode → sync deferred
- Disable battery saver → sync resumes
- Check battery settings → Kordant background usage minimal
- Trigger manual sync → data updates immediately

notes:
- WorkManager is already included (libs.work.runtime.ktx)
- Minimum periodic work interval is 15 minutes
- Android 12+ has stricter background restrictions
- Use Foreground Service for urgent syncs if needed