Error handling

Task error envelope (create / query)

{ "code": "invalid_request", "message": "...", "data": null }

Download error envelope (/content)

{ "error": { "message": "...", "type": "invalid_request_error" } }

HTTP status codes

HTTP	Scenario
`400`	Bad params / task not finished (/content returns 400 before completion)
`401`	Auth failed
`404`	Task not found / model not listed
`429`	Rate limited (group upstream saturated) / out of balance
`5xx`	Upstream error

> A failed run still returns HTTP 200 with status=failed; failed tasks are fully refunded.