# 13. Call Screening Service Production Hardening

meta:
  id: android-production-13
  feature: android-production
  priority: P1
  depends_on: []
  tags: [native-features, spamshield, production]

objective:
- Harden the CallScreeningService for production use with robust spam detection and minimal latency

deliverables:
- CallScreeningService production-ready
- Spam database local caching
- Real-time caller lookup
- Permission handling and user guidance

steps:
1. Audit existing service:
   - Review android/app/.../service/CallScreeningService.kt
   - Identify gaps in production readiness
   - Test current functionality
2. Implement local spam database:
   - Cache spam numbers locally (Room database)
   - Sync with backend periodically
   - Hash numbers for privacy
   - Support pattern matching (wildcards)
3. Optimize lookup performance:
   - Use indexed database queries
   - Target <100ms lookup time
   - Cache frequent lookups in memory
   - Use Bloom filter for fast negative checks
4. Add caller identification:
   - Display caller info for known contacts
   - Show spam likelihood percentage
   - Show spam category (telemarketer, scam, etc.)
5. Handle permissions:
   - Request CALL_SCREENING role
   - Guide user to Default Apps settings
   - Handle permission denial gracefully
   - Re-check permission on app launch
6. Add user controls:
   - Toggle for call screening
   - Toggle for call blocking
   - Manage blocked numbers
   - Report false positives/negatives
7. Add logging and analytics:
   - Log screened calls (anonymized)
   - Track block rate and accuracy
   - Report metrics to backend
8. Test thoroughly:
   - Test with simulated calls
   - Test on physical devices
   - Test with various carriers

tests:
- Unit: Test spam lookup logic
- Integration: Test CallScreeningService binding
- Device: Test with actual incoming calls

acceptance_criteria:
- CallScreeningService registered and active
- Local spam database synced daily
- Caller lookup <100ms
- Known spam calls blocked or flagged
- User can enable/disable screening
- Block list manageable from app
- Permission handling with user guidance
- False positive reporting mechanism
- No crashes during call handling
- Works on Android 10+ (API 29+)
- Battery impact minimal

validation:
- Enable call screening → incoming spam call blocked
- Check database → spam numbers cached locally
- Measure lookup time → <100ms
- Report false positive → number removed from block list
- Disable in app → screening stops

notes:
- CallScreeningService requires special role (not just permission)
- User must set app as default call screening app in Settings
- Different carriers may handle call screening differently
- Test thoroughly on physical devices with real SIM cards