Author: Cyrus Wong (黃俊彥) — Google Developer Expert - Cloud (AI), Senior Lecturer at HKIIT

1. Problem Statement: Defeating "Fake Video Playback", Proxy Classmates & Static Screen Decoys

In a 3-hour coding lab or a 100-student hybrid lecture, passive screen-share telemetry and traditional door-scan attendance have three classic blind spots:

The Static Screen Decoy (AFK) : A student opens VS Code or a lecture slide deck, starts screen sharing, and walks away from their workstation for 45 minutes while their screen capture continues uploading identical frames.

The "Give Password to a Classmate + Play a Pre-Recorded Video" Proxy Lab Exploit : Even worse, an absent student gives their account password to a friend sitting in the computer lab. That friend logs into the absent student's account on an adjacent lab PC, starts screen sharing, and plays a pre-recorded coding video in full-screen so the screen-capture feed looks like someone is typing code!…