What is cmux?

cmux is a macOS terminal application built specifically for people who run AI coding agents, tools like Claude Code, Codex, Gemini, OpenCode, and Amp, and often run several of them at once. The author got tired of using a generic terminal with split panes, because system notifications from coding agents all said the same thing ("Claude is waiting for your input") and gave no clue which session needed attention. cmux is the response to that pain point. The application is built on top of libghostty, the rendering engine behind the Ghostty terminal, so it draws text quickly using the GPU and reads your existing Ghostty config for themes, fonts, and colors. Its main additions are a sidebar with vertical tabs that show each workspace's git branch, linked pull request status, working directory, listening ports, and latest notification, plus a notification system that gives panes a blue ring and lights up tabs when an agent needs you. There is an in-app browser that can be split alongside the terminal and driven through a scriptable API, an SSH mode that creates a workspace for a remote machine and routes browser traffic through it, and a one-command launcher for Claude Code's teammate mode that opens teammates as native splits. Everything is controllable from a CLI and a socket API. Use cmux if you work heavily with AI coding agents on macOS and want a native, fast terminal that surfaces which agent needs attention without forcing you into a particular workflow. It is written in Swift and AppKit (not Electron), installs via a DMG download or Homebrew cask, and auto-updates. The full README is longer than what was provided.