Pickcmux: Manage AI coding agent notifications and windows in the terminal

When running multiple AI coding agents simultaneously, such as Claude Code or Codex, windows can become mixed up, making it difficult to determine which task is waiting for input. cmux is a macOS native terminal based on Ghostty that solves this problem with vertical tabs and a notification system. When an agent is waiting for input, a blue border appears on the corresponding panel, and the sidebar tab lights up for immediate visibility.

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The sidebar displays each workspace's Git branch, linked PR status, working directory, listening ports, and more. The built-in browser supports the agent-browser API, allowing agents to interact directly with development servers. It can import cookies and sessions from existing browsers like Chrome to start in an authenticated state. Even when connected via SSH, the browser window routes through the remote network, making localhost access seamless.

Unlike Electron-based GUI orchestrators, cmux is built with Swift and AppKit, ensuring fast execution speed and low memory usage. It reads existing Ghostty configuration files as-is, and all features—including workspace creation, window splitting, and key input transmission—can be controlled via scripts using the CLI and Socket API. Designed to avoid rigid workflows, it provides only the fundamental elements of a terminal and browser, allowing developers to combine tools themselves.