cmux

A control tool for cmux, a macOS app that arranges terminals and browser panels in windows, workspaces, panes, and surfaces.

In plain words
What is it for?
Use it to list, create, focus, move, split, reorder, and identify cmux panels, or flash one to attract attention.
Why use it?
It removes the need to place and navigate panels by hand when automation must work with a specific multi-panel layout.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/djrhails/dotfiles/cmux
Any agent
npx skills add DJRHails/dotfiles --skill cmux
Clone the repo
git clone --depth 1 https://github.com/DJRHails/dotfiles

Made for: Claude Code, Codex.

Per session 68 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 875 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 88% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00068 $0.00875
Opus 5 $0.00034 $0.00438
Sonnet 5 $0.00014 $0.00175
Haiku 4.5 $0.00007 $0.00088

Measured 2d ago against content hash 02d5cc4522ce, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

cmux scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

88% identical to cmux — 10 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

modules/agents/skills/cmux/SKILL.md · 85 lines

How it starts

The opening of the file, as written. The whole thing — 85 lines — stays where its author put it; the contents beside it link to each section on GitHub.

cmux Core Control

Use this skill to control non-browser cmux topology and routing.

Core Concepts

  • Window: top-level macOS cmux window.
  • Workspace: tab-like group within a window.
  • Pane: split container in a workspace.
  • Surface: a tab within a pane (terminal or browser panel).

Fast Start

# identify current caller context
cmux identify --json

# list topology
cmux list-windows
cmux list-workspaces
cmux list-panes
cmux list-pane-surfaces --pane pane:1

# create/focus/move
cmux workspace create
cmux new-split right --panel pane:1
cmux move-surface --surface surface:7 --pane pane:2 --focus true
cmux split-off --surface surface:7 right
cmux reorder-surface --surface surface:7 --before surface:3

# attention cue
cmux trigger-flash --surface surface:7

Settings and Docs

Use cmux docs settings before changing cmux-owned settings. It prints the docs URL, schema URL, raw GitHub resources, cmux.json paths, and reload command.

cmux docs settings
cmux settings path

cmux-owned settings live in ~/.config/cmux/cmux.json. Legacy ~/.config/cmux/settings.json and ~/Library/Application Support/com.cmuxterm.app/settings.json files are read only as fallback for missing keys. Before editing, copy any existing cmux.json file to a timestamped .bak next to it so the user can revert. Edit the user file, then reload:

cmux reload-config

cmux reload-config reloads BOTH cmux.json and Ghostty config (~/.config/ghostty/config) and refreshes terminals in place. No app restart needed.

Use cmux settings for app behavior, sidebar, notifications, browser behavior, automation, workspace colors, and cmux-owned shortcuts. Terminal rendering settings such as font, cursor style, theme, scrollback, background transparency (background-opacity), and blur (background-blur) belong in Ghostty config at ~/.config/ghostty/config.

Open the UI when useful:

cmux settings
cmux settings cmux-json
cmux settings shortcuts

Handle Model

Read the full file on GitHub · 85 lines

Files

What ships with it

4 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 85 lines · 68 tokens per session scan A 02d5cc4522ce

Subscribe to this mod's changes

cmux is a skill published in the GitHub repository DJRHails/dotfiles (2 stars, last pushed 8d ago), licensed MIT. It adds 68 tokens to every session and 875 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. It is 88% identical to cmux, differing in 10 lines, and is treated as a copy.

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