Idempotency-Key header on POST /v1/orders and a retry with the same key never
charges you twice.
Response
Idempotency-Key and you get the same order
(bbc26d24-…) back, charged once — never a second order.
Use a fresh unique key (a UUID) per distinct order, and reuse the same key when
retrying that same order after a network error or timeout.
How it behaves
- Same key, same body → you get the original order back, charged exactly once.
- Same key, different body →
422 idempotency_key_reused. The key is bound to its first request; do not reuse a key for a different order. - Same key, still processing →
409 request_in_progress. The first request has not finished; retry after a short delay. - No key on a mutating request →
400 idempotency_key_missing.