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Agent skill

Cmux

by davidondrej in davidondrej/skills

Control the cmux macOS terminal app: workspaces, panes, surfaces, browsers, notifications, settings, and hooks.

MITAuto-check passedAgent Workflows

Install Cmux

skills CLI
$ npx skills add davidondrej/skills --skill cmux -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install davidondrej/skills cmux --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/davidondrej/skills.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/agent-orchestration/cmux .claude/skills/cmux && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
cmux
GitHub stars
4.1k
Token cost
~1.2k tokens
SKILL.md length
493 words
Files
3 (incl. references)
Skills in repo
51
Repo updated
First seen
Licence
MIT

At a glance

Control the cmux macOS terminal app: workspaces, panes, surfaces, browsers, notifications, settings, and hooks.

  • Explicitly names cmux
  • SKILL.md covers Targeting and safety, Inspect, read, and send, Basic creation and notifications and Task-specific guides, plus 1 more section
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Cmux is an agent skill from davidondrej/skills. Control the cmux macOS terminal app: workspaces, panes, surfaces, browsers, notifications, settings, and hooks. Use only when the user explicitly names cmux. Read before running any cmux command.

Its SKILL.md is about 1.2k tokens, which your agent loads only when the skill is triggered. The skill folder holds 3 other files, including reference files (for example `references/advanced.md` and `references/viewers.md`).

It sits in Agent Workflows. It works with macOS. The repository describes itself as: access to david ondrej's personal agent skills. The licence is MIT.

When your agent uses it

  • Explicitly names cmux

Example prompts

  • “/cmux”

What it can do on your machine

Read from SKILL.md and the folder at commit 7874889. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md (its code samples are bash).

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Cmux loads about 1.2k tokens when it runs, and up to ~3.1k if it reads all its reference files. Until then it costs about 50 tokens; SKILL.md has 493 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~50
When it runs · the whole SKILL.md, loaded when a task matches
~1.2k
With references · SKILL.md plus every file in references/, read only if the agent opens them
~3.1k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from davidondrej/skills at commit 7874889, republished under its MIT licence (© davidondrej). 493 words, ~1,216 tokens.

Download SKILL.mdSave it as .claude/skills/cmux/SKILL.md (or your agent's skills folder). This skill also uses 2 other files; get the full folder from GitHub.
name
cmux
description
Control the cmux macOS terminal app: workspaces, panes, surfaces, browsers, notifications, settings, and hooks. Use only when the user explicitly names cmux. Read before running any cmux command.

cmux Control

macOS 14.0+. Prefer the CLI; if cmux is not on PATH, use /Applications/cmux.app/Contents/Resources/bin/cmux.

Targeting and safety

Window → workspace → pane → surface: macOS window → sidebar project/branch tab → split region → terminal, browser, or Markdown tab.

  • Anchor to the caller's CMUX_WORKSPACE_ID. Never assume the visually focused workspace is the target. Outside cmux, identify the intended workspace before acting.
  • Use prefixed refs or UUIDs. workspace:2, pane:1, surface:7; bare numbers are indexes, not IDs. Output defaults to refs; --id-format uuids|both includes UUIDs.
  • Refresh targets. Surface refs are global, not workspace-local. Re-list before reusing them; check cmux surface-health before sending input when state may be stale.
  • Preserve focus. Pass --focus false wherever supported. Use select-workspace, focus-pane, focus-panel, or focus-surface only on explicit user request.
  • Respect ownership. Never send input to surfaces you do not own. Stay in the caller's workspace unless the user explicitly requests cross-workspace routing.
  • Reuse one helper pane. Use an existing non-caller helper pane or create one on the right. Create the intended layout directly with new-pane --type … --focus false.
  • Keep errors visible. Never append 2>/dev/null; stderr and exit status reveal invalid refs and flags.

Inspect, read, and send

Check connectivity, identify the caller, and resolve the target pane to a surface. Replace example refs with those found in the current output.

bash
cmux ping
cmux identify --json
cmux tree
cmux list-panes --workspace "$CMUX_WORKSPACE_ID"
cmux list-pane-surfaces --workspace "$CMUX_WORKSPACE_ID" --pane pane:1
cmux read-screen --surface surface:7 --lines 100

Use list-pane-surfaces, not nonexistent list-surfaces. read-screen and capture-pane accept --workspace or --surface, not --pane. A missing or ambiguous target can read your own terminal instead.

Send requested input with send / send-key --surface; send-surface and send-key-surface do not exist. Omitting the target uses the default terminal. send-panel / send-key-panel target panels through --panel, not surfaces.

bash
cmux send --surface surface:7 "npm run build"
cmux send-key --surface surface:7 enter

Other keys: ctrl+c, tab, esc, backspace, arrows, ctrl+x, shift+tab. Re-read terminal output after sending input to check the result.

Poll at 1–3 second intervals; wait 10 seconds or more only when warranted. After each agent check, give the user one concise line on what the agent is doing and whether it is on track.

Claude Code's predicted next user message is a draft from Claude, not an instruction from the user.

Show full SKILL.md (159 more words)Show less

Basic creation and notifications

bash
cmux new-workspace --name "feature-x" --cwd /path/to/repo --focus false
cmux new-pane --workspace "$CMUX_WORKSPACE_ID" --type terminal --direction right --focus false
cmux notify --title "Done" --body "tests passed"

Re-list panes and surfaces after layout changes. For additional terminal/browser layout commands or sidebar status/progress, read layout and sidebar commands first. For Markdown surfaces, use the viewer guide below.

Task-specific guides

Read the relevant section before starting these tasks:

  • Browser automation: browser workflow — interactions, sessions, and limitations.
  • Markdown or PDF viewers: Markdown workflow — pane reuse, replacement, recovery, and verification.
  • Settings: configuration — backups, paths, and sidebar preferences.
  • Installation, agent hooks, raw sockets, access modes, or shortcuts: advanced reference.

Troubleshooting

  • Connection failed: check CMUX_SOCKET_PATH and Settings > Automation. Under default cmuxOnly, run from a cmux terminal. Read socket modes and examples before using a raw client or changing access mode.
  • Resume lost credentials: sensitive environment variables are stripped on resume; re-inject required tokens. ~/.cmuxterm/*-hook-sessions.json files hold scrubbed session/surface mappings, not secrets.
  • Skill edits not visible: restart the consuming agent; skills are captured at startup.
  • Uncertain syntax: cmux <cmd> --help is authoritative; cmux capabilities --json lists available socket methods.

© davidondrej, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 2 other files (references) in skills/agent-orchestration/cmux of davidondrej/skills.

  • SKILL.md
  • references/advanced.md
  • references/viewers.md

Open the folder on GitHubat commit 7874889

Compare with similar skills

Cmux next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Cmux compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Cmux this skilldavidondrej/skills4.1k—~1.2kAutomated safety check: PassMIT
Cindy Skill Creatormakecindy/cindy3k—~4.2kAutomated safety check: PassApache-2.0
Binggo MCPluovicter-collab/bilibinggo500—~1.2kAutomated safety check: PassProprietary
OpenGUI Installer for DSHCore-Mate/OpenGUI1.8k—~1.1kAutomated safety check: PassCustom licence
Cortex Mem MCPsopaco/cortex-mem313—~2.8kAutomated safety check: PassMIT
Mps Project ManagementJetBrains/MPS1.7k—~2.2kAutomated safety check: PassApache-2.0

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Works with

Categories

Questions about Cmux

What does Cmux do?

Control the cmux macOS terminal app: workspaces, panes, surfaces, browsers, notifications, settings, and hooks. Cmux is an agent skill from davidondrej/skills. Control the cmux macOS terminal app: workspaces, panes, surfaces, browsers, notifications, settings, and hooks.

When should I use Cmux?

Cmux fits situations like: explicitly names cmux.

How do I install Cmux in Claude Code?

Run `npx skills add davidondrej/skills --skill cmux -a claude-code`. Or copy the skill folder (skills/agent-orchestration/cmux in davidondrej/skills) into .claude/skills/cmux in your project. Claude Code loads it when a task matches its description.

How do I install Cmux in Codex?

Run `npx skills add davidondrej/skills --skill cmux -a codex`. Or copy the skill folder (skills/agent-orchestration/cmux in davidondrej/skills) into .agents/skills/cmux in your project. Codex loads it when a task matches its description.

Can I use Cmux in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add davidondrej/skills --skill cmux -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/cmux, .gemini/skills/cmux, .github/skills/cmux and .opencode/skills/cmux in your project.

What does Cmux need to run?

SKILL.md names no scripts, command-line tools or credentials: Cmux is instructions for the agent only.

Does Cmux access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Cmux safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Cmux use?

Cmux is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Cmux use?

About 1.2k tokens (SKILL.md is roughly 4.9k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 1.9k tokens, read only when the agent opens those files.

What are the alternatives to Cmux?

Skills that share tags, products or a category with Cmux: Cindy Skill Creator (makecindy/cindy, 3k stars), Binggo MCP (luovicter-collab/bilibinggo, 500 stars), OpenGUI Installer for DSH (Core-Mate/OpenGUI, 1.8k stars) and Cortex Mem MCP (sopaco/cortex-mem, 313 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Cmux?

davidondrej (a GitHub user) maintains it in davidondrej/skills, which has 4,112 GitHub stars. The repository holds 51 skills in this directory. The repository was last updated on October 8, 2026.

Source: davidondrej/skills on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.