Agent skill

Cmux

Orchestrate cmux terminal panes — split terminals, run parallel processes, read output from other panes, and use the built-in browser.

MITAuto-check passedAgent Workflows

Install Cmux

skills CLI

$ npx skills add espennilsen/pi --skill cmux -a claude-code

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

GitHub CLI

$ gh skill install espennilsen/pi 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/espennilsen/pi.git skills-src && mkdir -p .claude/skills && cp -r skills-src/extensions/pi-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/

Paste into Claude Code

Install the "cmux" agent skill from https://github.com/espennilsen/pi/tree/main/extensions/pi-cmux into .claude/skills/cmux/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "cmux", then confirm the skill loads.

Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

$skill-installer

$skill-installer install https://github.com/espennilsen/pi/tree/main/extensions/pi-cmux

Type this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.

skills CLI

$ npx skills add espennilsen/pi --skill cmux -a codex

Project install goes to .agents/skills/; add -g for ~/.codex/skills/.

GitHub CLI

$ gh skill install espennilsen/pi cmux --agent codex

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/espennilsen/pi.git skills-src && mkdir -p .agents/skills && cp -r skills-src/extensions/pi-cmux .agents/skills/cmux && rm -rf skills-src

Use ~/.agents/skills/ instead of .agents/skills for a personal install.

Codex skills documentation · loads skills from .agents/skills/

Paste into Codex

Install the "cmux" agent skill from https://github.com/espennilsen/pi/tree/main/extensions/pi-cmux into .agents/skills/cmux/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "cmux", then confirm the skill loads.

Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add espennilsen/pi --skill cmux -a cursor

Project install goes to .agents/skills/; add -g for ~/.cursor/skills/.

GitHub CLI

$ gh skill install espennilsen/pi cmux --agent cursor

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/espennilsen/pi.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/extensions/pi-cmux .cursor/skills/cmux && rm -rf skills-src

Use ~/.cursor/skills/ instead of .cursor/skills for a personal install.

Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/

Paste into Cursor

Install the "cmux" agent skill from https://github.com/espennilsen/pi/tree/main/extensions/pi-cmux into .cursor/skills/cmux/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "cmux", then confirm the skill loads.

Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

gemini skills install

$ gemini skills install https://github.com/espennilsen/pi.git --path extensions/pi-cmux

--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.

skills CLI

$ npx skills add espennilsen/pi --skill cmux -a gemini-cli

Project install goes to .agents/skills/; add -g for ~/.gemini/skills/.

GitHub CLI

$ gh skill install espennilsen/pi cmux --agent gemini-cli

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/espennilsen/pi.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/extensions/pi-cmux .gemini/skills/cmux && rm -rf skills-src

Use ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.

Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/

Paste into Gemini CLI

Install the "cmux" agent skill from https://github.com/espennilsen/pi/tree/main/extensions/pi-cmux into .gemini/skills/cmux/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "cmux", then confirm the skill loads.

Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

GitHub CLI

$ gh skill install espennilsen/pi cmux

Installs for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).

skills CLI

$ npx skills add espennilsen/pi --skill cmux -a github-copilot

Project install goes to .agents/skills/; add -g for ~/.copilot/skills/.

Manual copy

$ git clone --depth 1 https://github.com/espennilsen/pi.git skills-src && mkdir -p .github/skills && cp -r skills-src/extensions/pi-cmux .github/skills/cmux && rm -rf skills-src

Use ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.

GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/

Paste into GitHub Copilot

Install the "cmux" agent skill from https://github.com/espennilsen/pi/tree/main/extensions/pi-cmux into .github/skills/cmux/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "cmux", then confirm the skill loads.

GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add espennilsen/pi --skill cmux -a opencode

OpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.

GitHub CLI

$ gh skill install espennilsen/pi cmux --agent opencode

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/espennilsen/pi.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/extensions/pi-cmux .opencode/skills/cmux && rm -rf skills-src

Use ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.

OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/

Paste into OpenCode

Install the "cmux" agent skill from https://github.com/espennilsen/pi/tree/main/extensions/pi-cmux into .opencode/skills/cmux/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "cmux", then confirm the skill loads.

OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

Facts

Skill name: cmux
GitHub stars: 122
Token cost: ~723 tokens
SKILL.md length: 176 words
Files: 11
Skills in repo: 36
Repo updated: Sep 21, 2026
First seen: Oct 7, 2026
Licence: MIT

At a glance

Orchestrate cmux terminal panes — split terminals, run parallel processes, read output from other panes, and use the built-in browser.

Working inside cmux and you need to run a dev server
SKILL.md covers Available Tools, Common Patterns and Guidelines
Runs TypeScript scripts from its folder
Spawn sub-agents

What it does

Cmux is an agent skill from espennilsen/pi. Orchestrate cmux terminal panes — split terminals, run parallel processes, read output from other panes, and use the built-in browser. Use when working inside cmux and you need to run a dev server, watch tests, spawn sub-agents, or preview web pages.

Its SKILL.md is about 720 tokens, which your agent loads only when the skill is triggered. The skill folder holds 10 other files (for example `AGENTS.md`, `CHANGELOG.md` and `README.md`).

It sits in Agent Workflows, covering Subagents and Browser automation. The licence is MIT.

When your agent uses it

Working inside cmux and you need to run a dev server
Spawn sub-agents
Preview web pages

Example prompts

“/cmux”

Requirements

Node.js

What it can do on your machine

Read from SKILL.md and the folder at commit 79d019b. 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
Ships script files (TypeScript), which the agent can run.
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 723 tokens when it runs. Until then it costs about 64 tokens; SKILL.md has 176 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~64
When it runs · the whole SKILL.md, loaded when a task matches: ~723

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 espennilsen/pi at commit 79d019b, republished under its MIT licence (© espennilsen). 176 words, ~723 tokens.

Download SKILL.mdSave it as .claude/skills/cmux/SKILL.md (or your agent's skills folder). This skill also uses 10 other files; get the full folder from GitHub.

name: cmux
description: Orchestrate cmux terminal panes — split terminals, run parallel processes, read output from other panes, and use the built-in browser. Use when working inside cmux and you need to run a dev server, watch tests, spawn sub-agents, or preview web pages.

cmux Pane Orchestration

You have access to cmux tools for managing terminal panes. Use them to run parallel processes, monitor output, and interact with other terminals.

Available Tools

Tool	Purpose
`cmux_list`	List all surfaces (panes) and workspaces
`cmux_split`	Split pane right or down, optionally run a command
`cmux_read`	Read terminal output from another pane
`cmux_send`	Send text or keystrokes to another pane
`cmux_close`	Close a pane
`cmux_notify`	Send desktop notification
`cmux_browser`	Open/navigate/snapshot/click/fill/eval in built-in browser

Common Patterns

Dev server + coding workflow

1. cmux_split direction="down" command="npm run dev\n"
2. Note the surface ID from the result
3. Work on code in your main terminal (edit files, etc.)
4. cmux_read surface="surface:X" to check dev server output
5. cmux_close surface="surface:X" when done

Parallel test watching

1. cmux_split direction="right" command="npm test -- --watch\n"
2. Edit code in main pane
3. cmux_read surface="surface:X" to check test results
4. If tests fail, read the output and fix the code

Sub-agent spawning

1. cmux_split direction="right" command="pi \"Task description here\"\n"
2. Continue working on your own task
3. cmux_read surface="surface:X" to check sub-agent progress
4. cmux_close surface="surface:X" when sub-agent finishes

Web preview with browser

1. Start dev server: cmux_split direction="down" command="npm run dev\n"
2. Open browser: cmux_browser action="open" url="http://localhost:3000"
3. Get DOM: cmux_browser action="snapshot" surface="surface:X" compact=true
4. Interact: cmux_browser action="click" surface="surface:X" selector="button.submit"
5. Fill form: cmux_browser action="fill" surface="surface:X" selector="input[name=email]" value="test@example.com"

Stopping a process in another pane

1. cmux_send surface="surface:X" key="ctrl+c"
2. Wait a moment, then cmux_read to confirm it stopped

Guidelines

Always cmux_list first if you don't know the surface IDs
Append \n to commands in cmux_split and cmux_send to execute them
Read before assuming — use cmux_read to check what happened in other panes
Clean up — close panes you no longer need with cmux_close
Don't close your own pane — only close panes you created
Notify on completion — use cmux_notify for long-running tasks so the user knows
Surface IDs are like surface:2 — use the exact format from cmux_list or cmux_split results

Files

SKILL.md and 10 other files in extensions/pi-cmux of espennilsen/pi.

SKILL.md
AGENTS.md
CHANGELOG.md
README.md
client.ts
index.ts
logger.ts
package-lock.json
package.json
tools.ts
tsconfig.json

Open the folder on GitHubat commit 79d019b

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
Skill	Stars	Used in	Tokens	Auto-check	Licence	Repo updated
Cmux this skillespennilsen/pi	122	—	~723	Automated safety check: Pass	MIT	18 days ago
Moai Ref Aside Browsermodu-ai/moai-adk	1.2k	—	~1.1k	Automated safety check: Pass	Apache-2.0	today
Ship Featuretheexperiencecompany/gaia	308	—	~2.7k	Automated safety check: Notes	Custom licence	yesterday
Agent Orchestration SkillOpenLoaf/OpenLoaf	108	—	~919	Automated safety check: Pass	AGPL-3.0	4 mo ago
Unbrowseunbrowse-ai/unbrowse	780	—	~3.3k	Automated safety check: Pass	MIT	3 days ago
WebGPTNhahan/WebGPT	120	—	~1.4k	Automated safety check: Pass	MIT	16 days ago

Similar skills

Moai Ref Aside Browser
modu-ai/moai-adk
Safe-use reference for the optional Aside browser agent (the aside command-line tool and its MCP server), which works inside the operator's own logged-in browser.
1.2k GitHub stars~1.1k tokensUpdated today
Agent WorkflowsAuto-check passed
Ship Feature
theexperiencecompany/gaia
Autonomously ship a feature end-to-end with zero human intervention: plan it, implement it, review it with a team of subagents, boot the full stack, drive it in a real browser like a user…
308 GitHub stars~2.7k tokensUpdated yesterday
Agent WorkflowsAuto-check: notes
Agent Orchestration Skill
OpenLoaf/OpenLoaf
当主 Agent 面临多步骤复杂任务并正在判断要不要 / 怎样把子任务外包给内置子代理（browser / doc-editor / data-analyst / extractor / canvas-designer / coder 等）时触发。不用于：单步问答 / 读取 / 简单副作用（主 Agent 直接做）、已经明确要用 Agent 且知道 subagenttype 的场景。
108 GitHub stars~919 tokensUpdated 4 mo ago
Agent WorkflowsAuto-check passed
Unbrowse
unbrowse-ai/unbrowse
Search and call websites through Unbrowse's hosted API or remote MCP, reuse indexed site tools, read pages, and learn missing routes in its cloud browser.
780 GitHub stars~3.3k tokensUpdated 3 days ago
Agent WorkflowsAuto-check passed
WebGPT
Nhahan/WebGPT
Hands bounded tasks from Codex to a signed-in ChatGPT web session at a chosen reasoning level, or opens a terminal chat in your project that you control.
120 GitHub stars~1.4k tokensUpdated 16 days ago
Agent WorkflowsAuto-check passed
Turnstile Testing
jumodada/Drissionpage-MCP-Server
A skill your agent uses when testing an authorized Cloudflare Turnstile integration or operating an authorized production challenge with drissionpage-mcp.
487 GitHub stars~1.7k tokensUpdated 25 days ago
Agent WorkflowsAuto-check passed

Questions about Cmux

What does Cmux do?

Orchestrate cmux terminal panes — split terminals, run parallel processes, read output from other panes, and use the built-in browser. Cmux is an agent skill from espennilsen/pi. Orchestrate cmux terminal panes — split terminals, run parallel processes, read output from other panes, and use the built-in browser.

When should I use Cmux?

Cmux fits situations like: working inside cmux and you need to run a dev server; spawn sub-agents; preview web pages.

How do I install Cmux in Claude Code?

Run `npx skills add espennilsen/pi --skill cmux -a claude-code`. Or copy the skill folder (extensions/pi-cmux in espennilsen/pi) 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 espennilsen/pi --skill cmux -a codex`. Or copy the skill folder (extensions/pi-cmux in espennilsen/pi) 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 espennilsen/pi --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?

Going by SKILL.md and its folder, Cmux needs TypeScript for the scripts in its folder. Our summary lists: Node.js.

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 723 tokens (SKILL.md is roughly 2.9k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Cmux?

Skills that share tags, products or a category with Cmux: Moai Ref Aside Browser (modu-ai/moai-adk, 1.2k stars), Ship Feature (theexperiencecompany/gaia, 308 stars), Agent Orchestration Skill (OpenLoaf/OpenLoaf, 108 stars) and Unbrowse (unbrowse-ai/unbrowse, 780 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Cmux?

espennilsen (a GitHub user) maintains it in espennilsen/pi, which has 122 GitHub stars. The repository holds 36 skills in this directory. The repository was last updated on September 21, 2026.

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

Install Cmux

Facts

At a glance

What it does

When your agent uses it

Example prompts

Requirements

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

cmux Pane Orchestration

Available Tools

Common Patterns

Dev server + coding workflow

Parallel test watching

Sub-agent spawning

Web preview with browser

Stopping a process in another pane

Guidelines

Files

Compare with similar skills

Similar skills

More from espennilsen/pi

Related

Questions about Cmux