What is cmux-browser?

A procedure for controlling websites inside cmux browser panels. It covers opening pages, checking navigation, finding interactive elements, entering data, clicking, waiting for changes, and reading updated page content.

Use it to automate browser tasks in cmux, including opening sites, filling forms, selecting options, pressing keys, waiting for page states, and extracting information.

It reduces errors caused by acting on an outdated page or the wrong browser panel. Rechecking the page after navigation or interaction keeps the next action tied to the current screen.

cmux-browser — Skill for Codex by disler

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 disler/learning-cmux-with-agents --skill cmux-browser

Clone the repo

git clone --depth 1 https://github.com/disler/learning-cmux-with-agents

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/disler/learning-cmux-with-agents/cmux-browser/github.svg)](https://agentmods.dev/skills/disler/learning-cmux-with-agents/cmux-browser)

Your own site

<a href="https://agentmods.dev/skills/disler/learning-cmux-with-agents/cmux-browser"><img src="https://agentmods.dev/badge/skills/disler/learning-cmux-with-agents/cmux-browser/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/disler/learning-cmux-with-agents/cmux-browser"><img src="https://agentmods.dev/badge/skills/disler/learning-cmux-with-agents/cmux-browser.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 38 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,272 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.

Model	Per session	Once invoked
Fable 5.1	$0.00038	$0.01272
Opus 5	$0.00019	$0.00636
Sonnet 5	$0.00008	$0.00254
Haiku 4.5	$0.00004	$0.00127

Measured 10d ago against content hash 3dea0af2946c, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

cmux-browser 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 10d ago.

The scan reads SKILL.md. This mod also ships 3 executable files (templates/authenticated-session.sh, templates/capture-workflow.sh, templates/form-automation.sh), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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-browser — 95% identical, 2 lines differ

ai_docs/cmux-skills/cmux-browser/SKILL.md · 142 lines

How it starts

The opening of the file, as written. The whole thing — 142 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Browser Automation with cmux

Use this skill for browser tasks inside cmux webviews.

Core Workflow

Open or target a browser surface.
Verify navigation with get url before waiting or snapshotting.
Snapshot (--interactive) to get fresh element refs.
Act with refs (click, fill, type, select, press).
Wait for state changes.
Re-snapshot after DOM/navigation changes.

cmux --json browser open https://example.com
# use returned surface ref, for example: surface:7

cmux browser surface:7 get url
cmux browser surface:7 wait --load-state complete --timeout-ms 15000
cmux browser surface:7 snapshot --interactive
cmux browser surface:7 fill e1 "hello"
cmux --json browser surface:7 click e2 --snapshot-after
cmux browser surface:7 snapshot --interactive

Surface Targeting

# identify current context
cmux identify --json

# open routed to a specific topology target
cmux browser open https://example.com --workspace workspace:2 --window window:1 --json

Notes:

CLI output defaults to short refs (surface:N, pane:N, workspace:N, window:N).
UUIDs are still accepted on input; only request UUID output when needed (--id-format uuids|both).
Keep using one surface:N per task unless you intentionally switch.

Wait Support

cmux supports wait patterns similar to agent-browser:

cmux browser <surface> wait --selector "#ready" --timeout-ms 10000
cmux browser <surface> wait --text "Success" --timeout-ms 10000
cmux browser <surface> wait --url-contains "/dashboard" --timeout-ms 10000
cmux browser <surface> wait --load-state complete --timeout-ms 15000
cmux browser <surface> wait --function "document.readyState === 'complete'" --timeout-ms 10000

Common Flows

Form Submit

cmux --json browser open https://example.com/signup
cmux browser surface:7 get url
cmux browser surface:7 wait --load-state complete --timeout-ms 15000
cmux browser surface:7 snapshot --interactive
cmux browser surface:7 fill e1 "Jane Doe"
cmux browser surface:7 fill e2 "[email protected]"
cmux --json browser surface:7 click e3 --snapshot-after
cmux browser surface:7 wait --url-contains "/welcome" --timeout-ms 15000
cmux browser surface:7 snapshot --interactive

Read the full file on GitHub · 142 lines

Files

What ships with it

10 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.

10d ago First seen · 142 lines · 38 tokens per session scan A 3dea0af2946c

Subscribe to this mod's changes

cmux-browser is a skill published in the GitHub repository disler/learning-cmux-with-agents (109 stars, last pushed 2mo ago), licensed MIT. It adds 38 tokens to every session and 1,272 once invoked, about $0.0002 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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