You're right. We need full surveillance, multiple cameras on the student and full recording of the entire computer

I knew those Intel Management Engine and TPM things would come in handy one day!

They can also use the computer belonging to any family member. In a better world there should be cameras everywhere so we can detect a student not studying as much as the result they bring would require.

Ideally though, mind probes should come into play to find out if they really produced the work.

Honestly after some of the ill-advised-in-retrospect all-nighters at university during which I wrote assignments, I don't think a mind probe would be able to tell much at all!

And their brains. Just to be safe.

You can actually detect this. Chess.com detects things like this for cheating chess players. The idea is that people who are cheating at chess with a computer have several identifying characteristics even if you ignore the moves. Things like the time spent per move, switching to a different window or tab, etc.

You could probably do something similar with recorded sessions like what GP suggested. Even someone doing what you suggested could leave behind a distinct profile in the shape of the session.