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cmux

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

Skill by espennilsen

IndexedMIT★ 122
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Works with Claude Code, Claude apps, Codex, Cursor, Gemini CLI, GitHub Copilot, VS Code, OpenCode, Goose, Windsurf. Read the repository before you give any tool access to your data.

npx agentmarket install skill/espennilsen-cmux

Asks which of your tools to add it to (Claude Code, Codex, Cursor, VS Code, Windsurf, Gemini CLI, Claude Desktop) and shows the change first. See https://agentmart.dev/cli.

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About

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.

Use cases: backend

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Permissions

What this skill can do and what it asks for, from its SKILL.md. Checked Oct 25, 2026.

Tools
No tools found
Secrets
None asked for
Install scripts
None found
Runs as
Node.js package

Network hosts it talks to 1

  • codeload.github.com · found in install command

Files it touches

  • ~/.claude/skills/cmux

What's inside

Skill 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.
License
MIT
Instructions
69 lines in SKILL.md · view on GitHub

Before installing

  • Ships executable scripts

Agent Skills spec issues

  • name: "cmux" does not match folder "pi-cmux"

Files (11)

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

SKILL.md (first lines)

# 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

From espennilsen/pi, MIT.

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Signals

Stars
122
Forks
13
Open issues
1
Last commit (this folder)
Jul 29, 2026 (3 months ago)

From GitHub (fetched Oct 24, 2026).

Details

License
MIT
First seen
Oct 24, 2026
Last checked
Oct 24, 2026

More from espennilsen

Cite this page

cmux skill. Agent Mart. https://agentmart.dev/skills/espennilsen-cmux (last updated 2026-10-24)