The lecture leaves a contact sheet

During the two-hour CAD demo, a cron entry quietly hits GET /screenshot on the teaching desktop every three minutes. Each call captures the screen and stores it with a timestamp.

After class, the record is queryable. GET /api/v1/display/screenshots lists every capture; GET /screenshot/{timestamp} returns any single frame. A student who missed the constraint-setup step scrubs back to 14:32 and sees the exact dialog, the exact values. You paste three frames into the course notes instead of re-explaining on the forum.

No recording software ran. No 4GB video file got exported, uploaded, and scrubbed through at 1.5x. Forty stills, each addressable by URL, each showing one decision.