I kept leaving my laptop on café tables while I went to the counter, so I built Yowl, a small Mac menu-bar alarm. Arm it and unplugging the charger triggers a siren at full volume through the built-in speakers, even if the Mac was muted or connected to headphones. It also locks the screen. There are optional triggers for moving the laptop and closing the lid, plus optional photographs and phone alerts through ntfy. The interesting part to build was using the camera as a movement sensor. In a café, people walk past a stationary laptop constantly, so just checking whether the image changed produces false alarms. Yowl registers successive frames and looks for a single transformation explaining the whole scene moving. There is a live sensitivity readout so you can test it at your actual table. The permissions bit, up front: camera features are opt-in. The optional “keep screaming with the lid closed” feature needs administrator permission. In the current source, that installs one sudoers rule at /etc/sudoers.d/yowl-disablesleep, scoped to your user, allowing exactly these two commands: /usr/bin/pmset -a disablesleep 1 /usr/bin/pmset -a disablesleep 0 The rule uses absolute paths and fixed arguments, is validated with visudo, and is removed when you disable the feature. The sleep hold defaults to one minute and is capped at five, with a detached watchdog to release it if the app crashes. Leave that feature off and no rule is installed. Ordinary lid closure can silence an alarm by putting the Mac to sleep, so I would not treat lid-closed operation as an unconditional guarantee. Limitations: Repetitive backgrounds such as blinds, tiles and brick can defeat the camera movement detection. Command-Q and Force Quit can still stop it. So can holding the power button. Testing has been on my own Mac. The build is universal, but Intel reports would be useful; the lid sensor trigger needs supported Apple Silicon hardware. This is a deterrent, not a recovery system or a reason to leave a laptop unattended. Keep Find My and FileVault enabled. Free, MIT licensed, macOS 14+. No accounts or analytics. Photos stay local unless you enable phone alerts, which send them through your chosen ntfy topic. Download and walkthrough: https://dontstealmylaptop.com Source: https://github.com/nejcar20/yowl I'd especially appreciate reports of false alarms and how the sensitivity test behaves at different desks. Happy to discuss the camera detection or the macOS sleep problem.   submitted by   /u/nejcar20 [link]   [comments]