Cancel a queued music take: only before generation starts

You can cancel a Sume music job while it is still queued, but not after generation has started. The jobs and results docs, read 2026-10-03, say cancellation succeeds only before generation work starts; afterwards the API returns 409 job_generation_already_started with details.cancelable: false and the job runs to completion. Cancelling an already canceled job is idempotent and returns the same canceled job.

What happens to each state?

Only the member whose key or Agent turn created the job can cancel it.

How do I use this in an audition?

If you queued five takes and the first one is good enough, call POST /v1/jobs/:id/cancel on the rest straight away. Those still queued stop; any already generating still finish and bill. Check each job's status afterwards rather than assuming. The same tactic frees capacity when a workspace is hitting 429 queue_full, which the generation admission docs say you can resolve by cancelling queued jobs.

What is uncertain?

• How quickly a queued job moves to processing depends on your plan, so a cancel sent a minute late may get the 409.
• The cancel_url field in the job envelope may be null when cancelling is no longer possible; do not build on it as a guarantee.
• The docs do not say whether a cancel before generation refunds a hold in every case, so read your usage after a cancel.