Idempotency

POST /v1/deliveries requires an Idempotency-Key header. Use your own order reference.

Idempotency-Key: order-10432

Situation	Result
New key	Processed normally
Same key, same body	Original response replayed, Idempotency-Replayed: true
Same key, different body	409 idempotency_key_reuse
Same key, original still running	409 idempotency_in_progress

Keys are scoped to you and retained 24 hours.

Retries must be re-signed. A byte-identical resend: same timestamp, same signature: is refused as signature_replayed and never reaches the idempotency layer. Generate a fresh timestamp and signature for each attempt and keep the same Idempotency-Key. That key is what makes the retry safe, not the signature.

---