X-Cache: HIT together with X-Credits-Used: 0 to identify an uncharged cache response. Its age also depends on when the source produced the underlying data.
Use Cache-Control: no-cache when requesting a fresh source fetch. A successful fresh response is billed at the usual operation price.
Limit retries and increase the delay for temporary 429 or 5xx outcomes. A retry of the identical request should retain its Idempotency-Key; changing parameters while reusing that key causes HTTP 409. Do not automatically repeat a mutation without establishing that replay is safe.