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cmux-browser — Claude Code skill: what it does, how to install

Automates browser surfaces via the cmux CLI without stealing user focus. Useful for background page inspections, waiting on selectors, and form fills.

Install into Claude Code · Skills CLI (Vercel) All methods and platforms ↓ 
npx skills add manaflow-ai/cmux --skill cmux-browser -a claude-code
Open on GitHub

What cmux-browser does

The skill provides instructions for driving browser surfaces directly through the cmux binary. It supports creating background tabs, inspecting URLs, capturing interactive DOM snapshots, and clicking elements. Every surface-bound action requires an explicit --surface handle so commands never guess which window to target.

Surface discovery relies on read-only tree inspections like cmux tree --all --json. This setup lets the agent query window, workspace, and surface references without shifting active desktop focus. Element references go stale after navigation or modal shifts, making fresh snapshots mandatory before further interaction.

The host machine must already have the cmux CLI installed. Without that binary, none of the skill commands will run.

What it helps with

  • open browser tabs in the background without stealing active focus
  • discover surface handles across windows using json tree output
  • wait for specific selectors, text, or page load states
  • fill input fields and trigger element clicks via snapshot identifiers
  • inspect downloaded file history for a given browser surface

Example prompts for the agent

  • Open a background browser surface in cmux and return its surface reference
  • Find the browser surface for our dashboard in the cmux tree and take an interactive snapshot
  • Wait for the complete load state on surface:1 and click element e2

How to install cmux-browser

1Skills CLI (Vercel)

npx skills add manaflow-ai/cmux --skill cmux-browser -a claude-code

2Manually: put the files in place

~/.claude/skills/cmux-browser/SKILL.md

Copy the whole skill folder; for one project use .claude/skills/cmux-browser/

From the same set13

The whole set →
cmux manaflow-ai Skill for navigating multi-pane cmux layouts: create windows, workspaces, splits, focus surfaces, and move terminals and browser panels without breaking automation. Use it when an agent needs deterministic placement and routing. Claude Code CX Codex Cursor +1 9,600installs cmux-customization manaflow-ai Configures the cmux workspace manager: edits cmux.json, wires Command Palette actions, sets dock terminals, and routes terminal-level styling directly to Ghostty. Claude Code CX Codex Cursor +1 6,600installs cmux-diagnostics manaflow-ai Skill runs read-only cmux diagnostics: sockets, hooks, session restore, settings. Use when notifications fail, agents don't resume, or you need a support-safe debug report. Claude Code CX Codex Cursor +1 6,400installs cmux-keyboard-shortcuts manaflow-ai Configures cmux shortcuts in ~/.config/cmux/cmux.json. Useful for adopting tmux-style chords, auditing overrides, and validating syntax. Claude Code CX Codex Cursor +1 6,200installs cmux-testing manaflow-ai Skill for choosing verification scopes, adding tests, and validating Swift test targets in the cmux project. Decides what local and CI evidence a change needs. Claude Code CX Codex Cursor +1 4,900installs cmux-custom-sidebar manaflow-ai Skill for writing a custom cmux sidebar in a SwiftUI-like language. The sidebar binds to workspaces, tabs, PRs, and clock; hot-reloads on save; runs cmux commands on tap. Claude Code CX Codex Cursor +1 4,800installs cmux-architecture manaflow-ai Guides modular Swift package architecture, strict 5-layer dependency inversion, and Swift 6 concurrency rules in the cmux codebase. Claude Code CX Codex Cursor +1 4,800installs cmux-ghostty manaflow-ai Enforces workflow guidelines for the Ghostty submodule and GhosttyKit compilation in cmux. Useful when syncing the fork or committing submodule pointers. Claude Code CX Codex Cursor +1 4,700installs

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Questions about cmux-browser

How do I install cmux-browser in Claude Code?

Run npx skills add manaflow-ai/cmux --skill cmux-browser -a claude-code.

Why does cmux-browser require an explicit surface handle?

The CLI avoids inferring targets from visible focus. Passing --surface ensures navigation and clicks hit the intended pane every time.

What prerequisites are required before using this skill?

You need the cmux binary installed and available in your path. Verify it by running cmux --version.

See also

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