David shipped: Added per-document podcast button for workspace lecture documents

Kerra already had a workspace-level podcast feature. David wanted per-document audio generation — a more granular listen option surfaced right on the document:

go study how the lecture notes workspace podcast generation system works. i want to build the following: inside of a workspace document, near the top next to the test memo objectives buttons, i want a UI element button for "listen to this lecture" where, if clicked, it generates the podcast just for that document

David specified the full UX state machine:

and ensure that when the user clicks the button and the process starts, it shows an audio generating UI state and when its ready, it shows the UI in a ready state and that the player shows up in the bottom right of the screen but the player must be a specialised one wherein its different from the typical generic one

He caught a gap in the plan on the first pass:

okay wait but your plan doesnt seem to account for race conditions, failure modes, recoveries, retrying, not having UI states become stale and not actually indicative of truth etc

The feature reused the existing podcast script and audio generation infrastructure, adapted to accept a single document as input rather than the full workspace context.