Clamshell is a Mac menu bar app that keeps Apple Silicon MacBooks running with the lid closed, with no external display, admin password or privileged helper. The screen stays black but usable, so computer-use agents keep working. Sold directly at clamshell.dev ($9.99 one-time, 55 licenses) and on Setapp (~600 monthly active users, recurring revenue). Native Swift, macOS 14+, built by Clamshell Kft. in Budapest.