GooseNeck: Posture coach using your MacBook's hidden motion sensors.

Hey PH 👋 Solo dev here, building from Thailand. A few months ago I was poking around macOS internals and found something weird: every Apple Silicon MacBook ships with motion sensors Apple uses internally but never exposed to developers. There's an accelerometer in the chassis (the same one that knows when your Mac has been picked up) and a separate angle sensor in the hinge that reads exactly how far your lid is open. Both are readable through IOKit HID if you reverse-engineer the right vendor and usage IDs. So I built GooseNeck around them. How it works: - Reads the accelerometer to figure out how you're tilted toward the screen - Reads the lid angle to see when your screen position shifts - Compares both against a 5-second baseline you set when you sit down - Nudges you when posture has drifted past a threshold for 90 seconds - Live status sits in a Dynamic Island-style overlay at the notch, glanceable, no window to open It also catches typing fatigue by analyzing keyboard vibrations the accelerometer picks up. A Butterworth bandpass filter on the 5–45Hz range isolates typing intensity, and it watches for spikes above your session baseline. No keystroke logging. Just physics. No camera. No microphone. No cloud. No telemetry. ~2% CPU. Honest caveats since I'd want them if I were buying: - Private APIs mean it can't be on the Mac App Store. Direct download, Apple-notarized, Developer ID signed. - Apple Silicon only. Intel MacBooks don't have these sensors. - It detects laptop tilt + lid angle, not your spine directly. Catches "leaning into the screen" really well. Won't help if your laptop is on a stand and your back is still hunched. - Apple could change the internal interface in any macOS update. If they do, I patch it. Lifetime updates are part of the price. Small UX win I'm proud of - the notch finally earns its keep. Posture status is a glance away, no context switch, no app to open, no menu bar click.