Hey HN! I made this app because I bite my nails way too much while I code
It uses Mac's Vision library to track the location of your hands and mouth via the webcam.
Then when it catches you biting, it temporarily covers your screen with a big obnoxious warning. You have to stop biting if you want to continue seeing anything.
It's helped me a lot, so I hope it can help other nail-biters here :)