ADR-017: Offline Sync Protocol for Driver Hub

Status: ✅ Accepted Canonical file: ../../protocols/offline-sync-protocol.md

This ADR is documented in the protocols directory. See the canonical file for full details.

Summary

Establishes the offline sync protocol for the Driver Hub PWA, covering:

• Client queue structure (IndexedDB/RxDB PendingMutation interface)
• Sync API (POST /api/sync/batch with SyncBatchRequest/SyncBatchResponse)
• Per-record transactional batch semantics
• Deduplication via sync_idempotency_log table
• Server-side change_event generation
• "Server Wins" conflict resolution
• Connectivity detection and retry strategy

Applies to: OnboardSale, ExpenseReceipt, BoardingEvent, Incident, IssueReport.