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-template/browser-debug-setupgit clone --depth 1 https://github.com/udecode/plate-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 This is a copy
100% identical to browser-debug-setup — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
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-template (59 stars, last pushed 1mo 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). It is 100% identical to browser-debug-setup, differing in 0 lines, and is treated as a copy.
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.
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.
hard-cut
Remove a feature completely with no backward compatibility. Use when the user says "hard cut", "rip it out", "delete it", "unship", "kill this feature", or wants dead code removed instead of deprecated. Delete the surface, callers, tests, docs, comments, fallbacks, and stubs.