Internal-only: the timeline in the body with its sources presigned again, the way /internal/export_html presigned them for resolution.

An export that outlives its source URLs pauses and posts back the playlist its page was built with (the player's refreshMediaUrls export option). That timeline is re-signed, not the project as it is now: the project may have been edited since, and media removed from it meanwhile must still be readable for the render to finish. The page calls it with its own query string; the parameters that only shape the render (project, tracks, frames, ranges, audio, hdr) are ignored here. Nothing is saved. No permission check (internal use only).