Clamshell capabilities
Clamshell is a macOS menu-bar app from Epiphani Studios that keeps a MacBook running with the lid closed. Price: $9.99 one time, for every Mac the buyer uses, after a 7-day free trial. Runs on macOS 26 or later on Apple silicon. Last updated September 25, 2026.
| Capability | Mechanism | How to verify |
|---|---|---|
| Lid closed, on battery or plugged in, with or without an external display | A root LaunchDaemon (com.epiphani.clamshell.helper) sets pmset disablesleep 1 while holding | pmset -g | grep SleepDisabled reads 1 while held |
| Battery cutoff, 0 to 100% | The helper polls the internal battery every 5 seconds; at or under the cutoff on battery it clears the flag and runs pmset sleepnow | The window's "Stand down at" slider; /var/log/clamshell-once.log |
| Holds at any charge on the charger | The power-source check comes first; on AC the cutoff and the 8-hour limit do not apply | Plug in with the lid shut and a low charge |
| Thermal stop at 45°C | Battery temperature from the AppleSmartBattery registry entry (ioreg), read every 30 seconds; at 45°C the hold ends and the Mac sleeps, on the charger too | Helper log line "too hot to keep running shut" |
| 8-hour limit for a lid shut on battery | Minutes counted from when the lid shut on battery, persisted across helper restarts, reset by the charger or an open lid; on by default | Helper log line "shut on battery for 8 hours" |
| Finish up, then sleep | Menu item and global hotkey Control-Option-Command-P start a 20-minute timed hold; at the deadline the helper releases and runs pmset sleepnow | Menu: "Finish Up for 20 Minutes, Then Sleep" |
| Low Power Mode with the lid shut on battery | While holding on battery with the lid shut the helper runs pmset -b lowpowermode 1 if it was 0, and restores 0 on lid open, charger, release or uninstall; a Mac already in Low Power Mode is untouched | pmset -g | grep lowpowermode |
| Two modes | "For one time" ends when the lid next opens or at restart; "until I turn it off" resumes at boot | Menu bar rows |
| Closed-lid runtime forecast | Median drain rate from samples taken while held on battery (2 to 30 minute pairs, at least three); falls back to the system estimate, labeled as an estimate | The window's large number and its caption |
| Automatic updates | Checks updates.belstone.com/clamshell/appcast.json at launch and every 6 hours; verifies code signature, team ID 34MSZG2KRW and SHA-256 before swapping the bundle | Menu: Check for Updates |
| Distribution | Developer ID signed, notarized and stapled app and disk image | spctl -a -t open --context context:primary-signature -v Clamshell.dmg |
| License | Offline Ed25519 key bound to the buyer's email; a daily read of a refund list of email hashes | Menu shows "Licensed to ..." |
Constraints: runs on macOS 26 or later on Apple silicon; the first use asks for an administrator password once to install the helper.