cmux

// Overview

cmux is a native macOS terminal built on libghostty and aimed squarely at people running AI coding agents. A terminal is already where Claude Code, Codex, Gemini CLI and the rest live; cmux keeps that model but adds the bookkeeping those workflows need — vertical tabs that surface the git branch, pull-request status, listening ports and pending notifications for each session.

The core problem it targets is attention. When several agents are working at once, you need to know which one is blocked on a question and which is still grinding, so cmux shows a blue ring and a sidebar badge on any tab that wants you. Layouts, working directories and scrollback are restored between launches, so a set of long-running agent sessions survives a restart.

It is also programmable. cmux exposes a CLI and a Unix socket API, and ships a built-in browser with a scriptable API that an agent can drive, which means an agent can open a preview of the dev server it just started. Rendering is GPU-accelerated through libghostty, and remote work is covered by `cmux ssh`. The project is open source under GPL-3.0-or-later, with optional commercial terms; the app is written in Swift and AppKit, and iOS is in beta via TestFlight.

// What it does

• Vertical and horizontal tabs showing git branch, PR status, open ports and notification state per session
• Attention notifications — blue rings and sidebar badges — so you can tell which agent is waiting on you
• Built-in browser with a scriptable API that agents can drive for previews and automation
• Programmable through a CLI and a Unix socket API
• Session restoration of layouts, working directories and scrollback across restarts
• SSH support with `cmux ssh user@remote`, plus a `cmux claude-teams` integration
• GPU-accelerated rendering via libghostty

// Getting started

cmux is macOS-only. Install the signed app from the releases page, or use the project's Homebrew tap.

brew tap manaflow-ai/cmux
brew install --cask cmux

cmux ssh user@remote

Commands and code are distilled from the project's own documentation — always check the official repo for the latest.

// When to use it

• Reach for it when you keep several coding agents running and lose track of which one is blocked
• Use it when you want agent sessions — layout, directories and scrollback — to survive a restart
• Good when you want an agent to open and inspect a dev-server preview without leaving the terminal
• Useful for scripting terminal workflows through the CLI and socket API rather than clicking around

// How cmux compares

cmux alongside other open-source coding-agent harnesses & runtimes tools AI/TLDR tracks, ranked by GitHub stars.