cmux - Terminal Multiplexer

Overview

cmux is a native macOS terminal application (Swift/AppKit) that provides terminal multiplexing with workspaces, panes, and splits. It uses Ghostty's rendering engine (libghostty) for GPU-accelerated terminal output. The CLI communicates with the running app via a Unix domain socket at /tmp/cmux.sock.

Think of cmux as "tmux reimagined as a native macOS app" -- it has workspaces (like tmux windows), panes (like tmux panes), and surfaces (individual terminal or browser instances within panes), all controllable via a rich CLI.

When to Load the Reference

This skill covers the mental model, common commands, gotchas, and erk integration. Load references/cmux-reference.md when you need: