Idempotency and retries

Where an operation supports Idempotency-Key, reuse the key with the same request parameters when retrying that request. Use a new key for a new logical request. A repeat within 24 hours of a successful request that was charged or used a free allowance is not charged again: its response carries Idempotent-Replayed: true and Hippomundo-Charged-Milli-Credits: 0. The response is read again, so it may hold current data and a new next_page_token. A success that cost nothing for another reason is not recorded under the key, so a repeat of it is priced like a new request and carries no Idempotent-Replayed. A free page stays free. A free repeat of a request you paid for shortly before is charged once that free period has passed. Within 24 hours of a success that was charged or used a free allowance, the same key with different parameters returns idempotency_conflict. A key with no such success, or whose 24 hours have passed, takes different parameters as a new request.

Inspect the stable problem code and follow Retry-After when it is present. Use bounded retries with backoff. Errors are uncharged; a retry must still pass current authentication and authorization.