Poll a render started by POST /v1/media/generate-video with wait: false.

While the provider is still working this answers running and costs nothing — it reads the provider's status and returns. The poll that finds the render finished is the one that does the work: it collects the video, persists it as a durable team file, and bills. That means the FIRST successful poll carries the same result/applied/adjustments envelope the synchronous call returns, and later polls replay it.

Never charged twice. The delivery runs inside the shared idempotency envelope keyed on this task, so a concurrent duplicate poll gets the retryable 409 rather than a second charge, and the provider-job checkpoint underneath means no poll can ever resubmit the render.

Authorization is by the team that started the task; anything else is an existence-hiding 404.