A teacher forgot to mark attendance yesterday — can they catch up from their phone?

No. Attendance in the Teachers Portal is locked outside the session's own day, and the screen says why — the session has not started, or the day has passed. Catching up goes through an admin, who may correct attendance at any time.

That lock is not an oversight waiting to be fixed: attendance deducts a student's pack, so presence marked days later changes money with nobody checking. A substitute teacher gets the same right as the original teacher for that day.