The short version
Your camera is analyzed on your device, frame by frame, by a face-tracking model that
ships with this page. Frames are discarded immediately. No video, audio, or images are
recorded, uploaded, or sent anywhere. The page's security policy (connect-src 'self')
blocks every network connection except to its own files.
What is stored on your device
fs.settings: your settings (celebrations, dwell time).fs.calibration: your personal gesture thresholds, if you calibrate.fs.progress: points, badges, streaks, and per-gesture counts.fs.welcome: whether you have seen the welcome dialog.
Nothing else. No accounts, no analytics, no cookies. Open the Offline proof button on the home page to see a live log of every network request the page makes, try the app with the network fully simulated off, and delete all of your data with one button.
Camera
Your browser shows its camera indicator while the camera runs; a page cannot hide it. The camera turns fully off when you leave the practice, test, or calibration screens, or when you hide the tab.