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.
git clone --depth 1 https://github.com/hopchouinard/cmux-pluginWrote 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.
[](https://agentmods.dev/commands/hopchouinard/cmux-plugin/open-browser)<a href="https://agentmods.dev/commands/hopchouinard/cmux-plugin/open-browser"><img src="https://agentmods.dev/badge/commands/hopchouinard/cmux-plugin/open-browser.svg" alt="Measured on agentmods" height="20"></a>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 | $0.00051 | $0.00249 |
| Opus 5 | $0.00026 | $0.00125 |
| Sonnet 5 | $0.00010 | $0.00050 |
| Haiku 4.5 | $0.00005 | $0.00025 |
Grade A, and why
open-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 7d 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.
What it actually says
Open a cmux browser split for visual verification.
- Check we're inside cmux — if not, explain that this requires cmux and stop
- Get current surface ID from
cmux identify --json - Open a browser split to the right:
cmux browser surface:<id> open-split --direction right - Wait 1 second for the split to initialize
- Navigate to: $ARGUMENTS (if provided) or http://localhost:3000 (default)
cmux browser surface:2 navigate "<url>" - Take a snapshot to confirm the page loaded:
cmux browser surface:2 snapshot --compact - Report what you see — page title, any visible errors, key UI elements
If $ARGUMENTS contains a specific element to check (e.g. "localhost:8080 check the nav"), extract both the URL and the intent and act accordingly.
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.
- 7d ago First seen · 18 lines · 0 tokens per session scan A 7703b1be7c56
open-browser is a command published in the GitHub repository hopchouinard/cmux-plugin (6 stars, last pushed 5mo ago), licensed MIT. It adds 51 tokens to every session and 249 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 2026-08-31.
Other commands, from other repositories
browser-debug
A command recipe for starting Yandex Browser with remote debugging enabled through the Chrome DevTools Protocol, a browser control and inspection interface. It also checks whether the debugging connection is available.
gh-issue-use-cypress
Like /gh-issue-use-browser, but pinned to the Cypress MCP — use when your project runs the Cypress MCP for browser automation. Example — /gh-issue-use-cypress "Composer > Save" saving toasts failure but the record persists.
jira-issue-use-cypress
Like /jira-issue-use-browser, but pinned to the Cypress MCP — use when your project runs the Cypress MCP for browser automation. Example — /jira-issue-use-cypress "Composer > Save" saving toasts failure but the record persists.
interactive-dev
Start a persistent interactive development session with natural language browser control, auto-error monitoring, and full dev tool access.
extension-debug
Debug a running extension, inspect DOM, console, content script injection.
run_slash_command
Execute SN Utils slash commands on a ServiceNow tab. Particularly useful for debugging forms with /tn (show technical names).