If you have ever run three Claude Code sessions at the same time in a stock terminal, you know the pain. Notifications are generic ("Claude is waiting for your input" — every single time), tab titles blur together, and there is no good way to tell which agent needs you without clicking into each pane one by one. cmux was built to fix exactly this.
What Is cmux?
cmux is an open-source, native macOS terminal application built on top of Ghostty, the GPU-accelerated terminal emulator. It wraps Ghostty's rendering engine (libghostty) in a Swift/AppKit shell and layers on top the features that matter when you are managing multiple AI coding agents simultaneously:
Vertical tab sidebar showing git branch, linked PR status, working directory, listening ports, and the latest notification text for each workspace
Agent-aware notification rings — when an agent needs input, its pane gets a blue visual ring and the sidebar tab lights up
