Create assets

Create up to BATCH_MAX_ITEMS assets in a single request.

Each item supplies a content_url that the server fetches and re-hosts asynchronously. The response therefore describes rows in state PROCESSING — poll GET /v2/assets/{id} until state becomes READY or ERROR. A fetch failure surfaces as state=ERROR with a reason in status_msg, not as an error on this response.

The type supplied per item seeds the created row, but is provisional: the server re-derives it from the fetched content during ingest and that value wins.

Returns 200 if all items succeed, 207 if any fail, 400 if the envelope is empty or over the cap.

Rate limited more tightly than a plain row-writing batch endpoint: every accepted item converts one request into real egress, and video or audio items also start a transcription job.

Required OAuth scope: assets:write