# Retry and idempotency policy (NR5)

- `delivery_id`: UUIDv7; `dedupe_key`: hash(event_id + rule_id + channel_id).
- Backoff: exponential with jitter; base 2s, factor 2, max 5 attempts, cap 5 minutes between attempts.
- Connectors must be idempotent; retries reuse the same `dedupe_key` and must not duplicate sends.
- Out-of-order acks ignored: only monotonic `attempt` accepted.
- Record retry outcomes in receipts and include attempt count + reason.