Retry Backoff Service

Implements truncated exponential backoff with jitter (delay = min(base * 2^attempt + jitter, max_delay), base=30s, max_delay=3600s, jitter ±20%) for failed outbox mutations. Tracks per-item failure counts and transitions items to dead-letter state after a configurable threshold (default 10 retries), then dispatches a local notification.

Feature: Background Sync

retry-backoff-service

• Compute next retry delay using truncated exponential backoff with uniform random jitter
• Persist per-mutation attempt count within the outbox record
• Mark items as dead-letter after configurable maximum retry threshold
• Trigger local push notification when a mutation enters dead-letter state
• Expose retry schedule inspection for diagnostics panel