- Implement SyncQueueProcessor with 5-second polling interval - Add priority-based queuing (1-10 scale) - Add exponential backoff retry logic (1m, 5m, 15m, 1h, 24h) - Add stuck item detection (> 1 hour in processing state) - Add batch processing (50 items per cycle) - Add comprehensive test suite (15+ test cases) - Test enqueue/dequeue, priority ordering, retry logic, concurrent operations