For years, the boundary between a shared device and a private one has been drawn only by social trust — a fragile line. With Android 17 QPR2, Google is redrawing that line in code, giving Pixel users the ability to lock individual apps behind biometric or PIN authentication. The feature arrives not as a workaround or a third-party patch, but as a native part of the operating system — a quiet acknowledgment that personal security belongs in the foundation of a device, not bolted on afterward.