402, not 429; see
Errors. Two surfaces have a quota, per account:
The 429 body
retry_after is in seconds. The same value is sent as the Retry-After header.
Handling 429
Waitretry_after seconds, then send the same request again. A 429 is transient: the task,
the file, and the task_id are all still valid, so the retry picks up where it left off.
Polling is the usual cause. Poll GET /task/{task_id} no faster than once every few seconds,
or use GET /task/{task_id}/stream and let the server push events instead.