Threshold watches for your iPhone's Bluetooth signal — never connects to it — and locks your Mac automatically when you walk away. When you're back, it hands the screen straight to Touch ID or your Apple Watch. No cloud. No account. No password ever touches this app.
scripts/make-app-bundle.sh release · signed builds pending notarization credentialsThreshold is built as a strict pipeline — raw Bluetooth signal never touches the lock screen directly. Presence is inferred, evidence is weighed, and only then is a system effect requested and confirmed.
Most Bluetooth-proximity tools reach for whatever gets the job done fastest — an active connection, a private framework, synthesized keystrokes. Threshold takes the narrower path on purpose.
Threshold reads your trusted device's Bluetooth advertisements — the same kind of signal your AirPods use to show a battery level — and never opens a connection. Your phone never even sees this Mac.
Not stored, not typed, not simulated. Authentication is always handed back to macOS.
Uncertain sensor health or thin evidence means Threshold does nothing. It never guesses that you've left.
Everything runs on this Mac. Nothing to sign up for, nothing sent anywhere.
Every claim on this page is backed by a real-device measurement checked into the repo — not a marketing line.
The decision logic is pure and clock-free — every real-world timestamp comes from the edges, so the core is exhaustively testable.
A dropped Bluetooth signal from a dead radio looks nothing like a departed device to Threshold — and never gets treated as one.
No private frameworks. If it isn't documented and it isn't measured, it isn't in the supported list.
The primary path — an iPhone as your trusted device, Auto Lock, Wake on Return, Touch ID and Apple Watch native unlock — has been verified end to end on real hardware, including a full departure→lock→return→wake cycle. What's still open:
scripts/make-app-bundle.sh until a signed release exists.Threshold is Apache-2.0, maintainer-directed, and built in the open — every spike, every measurement, every known gap is in the repo, not hidden behind a marketing page.