400 invalid_request_error
Trigger: Request payload misses required fields or has invalid field types.
Fix: Validate model, mode, and input schema before request.
Retry: Retry only after fixing payload; avoid blind retries.
401 authentication_error
Trigger: Missing Authorization header or invalid API key.
Fix: Verify Bearer token format and API key scope.
Retry: Retry after auth fix; rotate key if repeated failures continue.
429 rate_limit_exceeded
Trigger: Request rate, concurrency, or current quota hits upstream rate limiting.
Fix: Apply exponential backoff first, then review request rate, concurrency, and quota usage.
Retry: Use exponential backoff (e.g., 1s/2s/4s) with jitter; if it persists, reduce submission pressure.
500 internal_error
Trigger: Transient upstream error or internal processing failure.
Fix: Capture request id and trigger retry workflow.
Retry: Retry 2-3 times with short delays; escalate if persistent.