What is nekoro-browser AGENTS.md?

Project instructions for nekoro-browser, a tool that lets an AI agent control a user's everyday Chrome through a browser extension and a local helper program. It preserves the browser's existing login state instead of requiring a separate remote-debugging setup.

Use them when modifying nekoro-browser, especially its Chrome extension, local daemon, browser-tab lifecycle, WebSocket connection, or command-line helpers.

They give contributors clear priorities and describe how the extension, local program, and browser-control connection fit together. They also require failures to be reported honestly rather than pretending an action succeeded.

How zeshuochen/nekoro-browser configures Codex and OpenCode

Reuse

Borrowing it

Nothing to install: this file belongs to zeshuochen/nekoro-browser. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/zeshuochen/nekoro-browser/master/AGENTS.md

Clone the repo

git clone --depth 1 https://github.com/zeshuochen/nekoro-browser

Made for: Codex, OpenCode.

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/instructions/zeshuochen/nekoro-browser/agents-md/github.svg)](https://agentmods.dev/instructions/zeshuochen/nekoro-browser/agents-md)

Your own site

<a href="https://agentmods.dev/instructions/zeshuochen/nekoro-browser/agents-md"><img src="https://agentmods.dev/badge/instructions/zeshuochen/nekoro-browser/agents-md/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/instructions/zeshuochen/nekoro-browser/agents-md"><img src="https://agentmods.dev/badge/instructions/zeshuochen/nekoro-browser/agents-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 706 This file is loaded in full into every session.

When invoked 706 The same file — it is already loaded in full.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

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	$0.00706	$0.00706
Opus 5.5	$0.00282	$0.00282
Sonnet 5.5	$0.00141	$0.00141
Haiku 4.5	$0.00071	$0.00071

Measured 1mo ago against content hash f9e73e7f540b, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

nekoro-browser AGENTS.md 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 1mo 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.

AGENTS.md · 52 lines

How it starts

The opening of the file, as written. The whole thing — 52 lines — stays where its author put it; the contents beside it link to each section on GitHub.

nekoro-browser is a CLI that lets an agent drive the user's daily Chrome via a MV3 extension (chrome.debugger API) + a local daemon, keeping the real login state — no --remote-debugging-port (Chrome 136+ blocks that on the default profile anyway).

Code priorities

Clarity
Precision
Low verbosity
Never fabricate success — helpers return {"ok": false, "error": ...} on failure, not a silently-wrong {"ok": true}

Overview

Two halves, one wire (HTTP + WebSocket, same port):

extension/ — MV3 extension. background.js is the service worker: WS transport to the daemon, chrome.debugger attach/CDP dispatch, dialog auto-handling, tab lifecycle. keepalive.js is a content script that gives the service worker an independent wake vector (MV3 workers get evicted; a plain WS/alarm keep-alive alone isn't reliable).
src/nekoro_browser/ — the daemon + CLI.
- daemon.py — long-lived middleman process between the extension and the agent's -c code
- bridge.py — the WS/HTTP transport
- lifecycle.py — pid file, process fingerprint, stale-daemon self-heal
- helpers.py — CDP wrapper functions auto-imported into -c scripts, each a thin (≤10 line) wrapper over one CDP capability
- cli.py — the nekoro-browser command
- mcp_server.py — the nekoro-browser-mcp command: stdio JSON-RPC MCP server for clients that don't read skill files (Claude Desktop, Cursor, opencode, Codex, VS Code/Copilot, …). Tools are reflected off helpers.py via inspect.signature, then forwarded to the same daemon /exec endpoint the CLI uses — no second execution path to keep in sync.

SKILL.md tells agents how to use the CLI and lists every helper. README.md covers install + quick start for humans.

An agent operating nekoro-browser edits two places:

src/nekoro_browser/agent_helpers.py — task-specific browser helpers the agent adds at runtime; hot-reloaded via reload_agent_helpers(), no daemon restart needed
domain-skills/ — Markdown notes on specific sites, written and read by the agent. Empty by default and never imported; workflows go in agent_helpers.py.

Read the full file on GitHub · 52 lines

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.

1mo ago Changed · +4 lines · +56 tokens per session f9e73e7f540b
2mo ago First seen · 48 lines · 650 tokens per session scan A ecd52513ee2c

Subscribe to this mod's changes

nekoro-browser AGENTS.md is an instructions file published in the GitHub repository zeshuochen/nekoro-browser (5 stars, last pushed 1mo ago), licensed MIT. It adds 706 tokens to every session, about $0.0028 per session on Opus 5.5. 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.

ai-agent browser-automation cdp chrome-devtools-protocol chrome-extension llm-tools

nekoro-browser AGENTS.md next to 6 instructions from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
nekoro-browser AGENTS.mdzeshuochen/nekoro-browser	Instructions file	5	1mo ago	MIT	A	706	Codex, OpenCode
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vscode copilot-instructions.mdmicrosoft/vscode	Instructions file	195k	today	MIT	A	3,093	GitHub Copilot
vscode ai-customization.instructions.mdmicrosoft/vscode	Instructions file	195k	today	MIT	A	1,907	GitHub Copilot

nekoro-browser: Instructions file for Codex