cmux Skill for Claude Code

A Claude Code skill for managing cmux panels during software development — open files in Neovim, view git diffs with delta, and run commands in split panes, all by talking to Claude.

What it does

Say things like:

You say	What happens
"open the code"	Claude finds the relevant file and opens it in nvim in a right panel
"show me the diff"	Opens git diff in a bottom panel (rendered by delta)
"run the tests in a new pane"	Runs your test command in a split panel
"start the dev server"	Opens a right panel with your dev server running
"open both files side by side"	Two nvim panels side by side

Installation

One-liner

curl -fsSL https://raw.githubusercontent.com/jhta/cmux-skill/main/install.sh | bash && source ~/.zshrc

This will:

• Install Neovim and delta via Homebrew (if not already installed)
• Symlink the cmux CLI
• Clone the skill into ~/.claude/skills/cmux
• Add helper functions to your ~/.zshrc / ~/.bashrc
• Configure git to use delta with side-by-side, line numbers, and dark mode
• Wire up Claude Code hooks so cmux gets notified when Claude starts, stops, or sends a notification
• Reload your shell so helpers are immediately available

Manual installation

Step-by-step

1. Requirements

• cmux (native macOS terminal)
• Neovim — brew install neovim
• delta — brew install git-delta
• Claude Code running inside a cmux workspace

2. Clone into your Claude skills directory

git clone https://github.com/jhta/cmux-skill ~/.claude/skills/cmux

3. Symlink the cmux CLI

sudo ln -sf "/Applications/cmux.app/Contents/Resources/bin/cmux" /usr/local/bin/cmux

4. Source the helper functions in your shell

Add to ~/.zshrc or ~/.bashrc:

source ~/.claude/skills/cmux/scripts/cmux-helpers.sh

5. Configure delta as your git pager

git config --global core.pager delta
git config --global interactive.diffFilter "delta --color-only"
git config --global delta.navigate true
git config --global delta.dark true
git config --global delta.side-by-side true
git config --global delta.line-numbers true
git config --global merge.conflictstyle diff3
git config --global diff.colorMoved default

6. Enable socket access in cmux

cmux Settings → Security → Socket API → "cmux processes only" (default).

Shell helpers

Once sourced, you can also use these directly in your terminal:

cmux-split right "nvim src/index.ts"   # open file in right panel
cmux-vim src/components/Button.tsx     # shorthand for nvim in right panel
cmux-diff                              # git diff in bottom panel
cmux-diff-staged                       # staged diff
cmux-show abc1234                      # show a commit
cmux-run "npm test"                    # run command, keep panel open after
cmux-tail logs/app.log                 # tail a log file
cmux-done "Build complete"             # send a macOS notification

How splits work

cmux CLI pattern (two steps):

# 1. Create the split — returns "OK surface:3 workspace:1"
cmux new-split right

# 2. Send a command to that surface (trailing newline executes it)
cmux send --surface surface:3 "nvim src/index.ts
"

The cmux-split helper wraps both steps into one call.

File structure

cmux/
├── SKILL.md                  # Main skill definition (auto-loaded by Claude Code)
├── references/
│   └── socket-api.md         # Full cmux socket API reference
└── scripts/
    └── cmux-helpers.sh       # Bash helper functions