cmux

cmux is a skill for Codex from nikships/skills-registry. It costs 50 tokens per session (732 once invoked), scanned A, original, Apache-2.0.

A command-line tool for controlling the layout and navigation of cmux, a macOS terminal and browser-panel application.

In plain words
What is it for?
Creating splits, moving or reordering terminal and browser surfaces, focusing the right panel, inspecting the current layout, and triggering an attention flash.
Why use it?
It lets automation identify and place windows, workspaces, panes, and surfaces consistently instead of relying on uncertain visual navigation.

Skill for Codex

Written for Codex: agents/openai.yaml present. Also seen: installed under .agents/ (shared by several agents).

Good fit Creating splits, moving or reordering terminal and browser surfaces, focusing the right panel, inspecting the current layout, and triggering an attention flash.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/nikships/skills-registry/cmux
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.

Any agent
npx skills add nikships/skills-registry --skill cmux
Clone the repo
git clone --depth 1 https://github.com/nikships/skills-registry

Made for: Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for cmux

README.md
[![agentmods](https://agentmods.dev/badge/skills/nikships/skills-registry/cmux/github.svg)](https://agentmods.dev/skills/nikships/skills-registry/cmux)
Your own site
<a href="https://agentmods.dev/skills/nikships/skills-registry/cmux"><img src="https://agentmods.dev/badge/skills/nikships/skills-registry/cmux/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for cmux

Your own site · 80×15
<a href="https://agentmods.dev/skills/nikships/skills-registry/cmux"><img src="https://agentmods.dev/badge/skills/nikships/skills-registry/cmux.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 50 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 732 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found 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 5.1 $0.00050 $0.00732
Opus 5 $0.00025 $0.00366
Sonnet 5 $0.00010 $0.00146
Haiku 4.5 $0.00005 $0.00073

Measured 12d ago against content hash 9479a77bd9a7, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, 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 12d 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

Copies of this mod

1 near-identical copy found in the catalogue:

  • cmux — 88% identical, 10 lines differ
.agents/skills/cmux/SKILL.md · 81 lines

How it starts

The opening of the file, as written. The whole thing — 81 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 new-workspace
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

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, and scrollback belong in Ghostty config.

Open the UI when useful:

cmux settings
cmux settings cmux-json
cmux settings shortcuts

Handle Model

  • Default output uses short refs: window:N, workspace:N, pane:N, surface:N.
  • UUIDs are still accepted as inputs.
  • Request UUID output only when needed: --id-format uuids|both.

Deep-Dive References

Reference When to Use
references/handles-and-identify.md Handle syntax, self-identify, caller targeting
references/windows-workspaces.md Window/workspace lifecycle and reorder/move
references/panes-surfaces.md Splits, surfaces, move/reorder, focus routing
references/trigger-flash-and-health.md Flash cue and surface health checks
../cmux-browser/SKILL.md Browser automation on surface-backed webviews
../cmux-markdown/SKILL.md Markdown viewer panel with live file watching

Read the full file on GitHub · 81 lines

Files

What ships with it

5 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. 12d ago First seen · 81 lines · 50 tokens per session scan A 9479a77bd9a7

Subscribe to this mod's changes

cmux is a skill published in the GitHub repository nikships/skills-registry (17 stars, last pushed yesterday), licensed Apache-2.0. It adds 50 tokens to every session and 732 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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