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.
npx agentmods add rules/udecode/plate-playground-template/browser-debug-setupgit clone --depth 1 https://github.com/udecode/plate-playground-templateWhat 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 | $0.00043 | $0.01132 |
| Opus 5 | $0.00022 | $0.00566 |
| Sonnet 5 | $0.00009 | $0.00226 |
| Haiku 4.5 | $0.00004 | $0.00113 |
Grade A, and why
browser-debug-setup scanned grade A with 1 finding 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 yesterday.
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.
Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
curl -sS http://127.0.0.1:9222/json/version Copies of this mod
1 near-identical copy found in the catalogue:
- browser-debug-setup — 100% identical, 0 lines differ
How it starts
The opening of the file, as written. The whole thing — 125 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Browser Debug Setup
Use this skill when dev-browser --connect http://127.0.0.1:9222 fails because
no persistent debug browser is running yet.
Goal
Get the user onto one persistent browser/profile that both the human and the
agent reuse. Minimize the Allow remote debugging? popup by keeping one
dedicated debug browser/profile alive.
Rules
- Prefer one permanent debug browser/profile over disposable automation browsers.
- Treat a custom
--user-data-diras mandatory, not optional. Chrome 136+ basically wants remote debugging to happen from a dedicated profile. - Keep auth in that profile. Do not fall back to cookie dumps or state files unless the user asks.
- Use a separate signed-in Chrome profile for browser work, like
dev. Do not use the user's normal dailyDefaultprofile as the source profile. - Clone that separate signed-in Chrome profile into the dedicated debug
--user-data-dir; do not point9222straight at the user's daily Chrome data dir. - On macOS, use
open -na "Google Chrome" --args ...for the debug browser. That starts a separate Chrome instance with the dedicated debug profile without touching the user's normal Chrome window.
Preferred Shape
Use a dedicated browser/profile with:
--remote-debugging-address=127.0.0.1--remote-debugging-port=9222- a persistent
--user-data-dir=<debug-profile-dir>
Sign in once in that dedicated browser and keep reusing it for agent work.
Quick sanity check:
curl -sS http://127.0.0.1:9222/json/version
Healthy output includes a JSON object with webSocketDebuggerUrl. Empty output
or 404 means the wrong process owns 9222.
Then verify dev-browser:
dev-browser --connect http://127.0.0.1:9222 <<'EOF'
const page = await browser.getPage("persistent-main");
console.log(await page.title());
EOF
If dev-browser --connect http://127.0.0.1:9222 still cannot resolve CDP even
though /json/version is healthy, connect with the exact websocket URL:
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.
- yesterday First seen · 125 lines · 43 tokens per session scan A 3a76ebbfede0
browser-debug-setup is a cursor rule published in the GitHub repository udecode/plate-playground-template (240 stars, last pushed 11d ago), licensed MIT. It adds 43 tokens to every session and 1,132 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
Other cursor rules, from other repositories
dev-browser
Fallback browser automation with persistent Chrome state. Use only when Browser Use is unavailable or blocked.
browser-debug-setup
One-time setup for a persistent debug browser on 127.0.0.1:9222 for dev-browser --connect. Use when browser work is needed but no reusable debug browser is running yet.
agent-browser-issue
Open a concise GitHub follow-up for reusable browser-use limitations. Use when browser automation is blocked by a likely tool-side issue that is worth fixing separately, especially for clicks, dropdowns, file inputs, focus traps, or other repeatable agent/browser failures.
testing
Cursor rule "testing" from udecode/plate-template, covering testing goal, core rules, seam selection, fixtures and assertions and quick reference.
components
React component architecture for creating composable, accessible components with data attributes. Use when creating/updating composable components, not for higher-level feature/page components.
react
React patterns with destructured props, compiler optimization, Effects, and Tailwind v4 syntax. ALWAYS use when using React.