Regenerate one rejected variant on Sume: use a new key

Luma Variants shows a Preview of each variant and lets you regenerate anything that is not right before you ship the Finals. On Sume, a redo is a new paid job, and it needs a new Idempotency-Key. Sending the old key again does not regenerate: a replay returns the original job.

Luma's flow is from its launch post. Sume's key rules are from Video generation and Generation admission, read 2026-10-01.

What does the same key do?

Two outcomes, depending on the body. With the same payload, the call is an exact retry and returns the original job. With a different payload, it fails with 409 idempotency_conflict: the same key was reused for a different operation or payload.

How should I key a regeneration?

Add a revision to the cell key: ad-3-9x16-es-r1, then -r2. Change something in the request, such as the prompt wording, since an identical body with a new key simply pays for another run of the same request.

What happens to the rejected job?

If it completed, you paid for it; Sume captures reserved usage on success. Failed jobs and failed queue admission release or refund the reservation. A job still queued that you no longer need can be canceled before generation starts, after which cancel returns 409 job_generation_already_started.

Where do I read more about keys?

The background is in idempotency keys for AI video APIs, and the conflict error is explained in idempotency conflict vs key in use.