A student's sessions run out mid-term — what happens?

That student's attendance is locked until the pack is refilled. The attendance screen disables their row and states the situation, and forcing a save is still refused, naming the student — so no presence is ever recorded without a session to deduct it from.

For a continuing class, the student's card offers a new pack for sale. For a fixed-session class, an empty pack means the student has finished instead: the state shows as Completed in green, with no refill prompt and no alarm.

Two things still work while a pack is empty: correcting attendance that was already saved, and marking a student who came in on a make-up right — that session was paid for earlier.