Windows

Never re-initialize the camera in-process on Windows

Tearing down and re-creating a MediaCapture inside a running process can wedge the Windows Camera Frame Server for the whole machine, with a persistent E_HANDLE until the service is restarted. The only reliable recovery is a fresh process, and the fix that stuck was deleting the code that could do otherwise.

Deciding to lock your screen should be a pure function

PresenceLock locks your Windows session when you step away from the webcam. Twice it silently stopped locking while reporting that it was watching. Both bugs were caught, and both fixes were possible, because the decision to lock is a pure F# function with no clock and no I/O.