[fintech-sdk/unit-sdk]: every failed call rejects with a UnitError carrying the HTTP status, Unit's request ID, the JSON:API error objects, and a retryable flag; log error.requestId with your support tickets. The client auto-retries 429 and 5xx with exponential backoff and jitter honoring Retry-After, configurable via retryPolicy. POST/PATCH get an auto-generated Idempotency-Key so retries never double-submit payments; supply your own key for operations you control explicitly.

Context: Calls to the Unit API fail and you need the right fields for logging and retry decisions.