What is browser-operator-core CLAUDE.md?

Repository instructions for Browser Operator, an AI-enabled browser based on Chrome DevTools that lets agents automate web tasks.

Use them to install dependencies, configure API keys, build the browser, run watch builds, and serve the generated DevTools files.

They collect the project overview, setup requirements, build commands, and local serving steps in one place.

How BrowserOperator/browser-operator-core configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to BrowserOperator/browser-operator-core. 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/BrowserOperator/browser-operator-core/main/CLAUDE.md

Clone the repo

git clone --depth 1 https://github.com/BrowserOperator/browser-operator-core

Made for: Claude Code.

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/browseroperator/browser-operator-core/claude-md/github.svg)](https://agentmods.dev/instructions/browseroperator/browser-operator-core/claude-md)

Your own site

<a href="https://agentmods.dev/instructions/browseroperator/browser-operator-core/claude-md"><img src="https://agentmods.dev/badge/instructions/browseroperator/browser-operator-core/claude-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/browseroperator/browser-operator-core/claude-md"><img src="https://agentmods.dev/badge/instructions/browseroperator/browser-operator-core/claude-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 1,984 This file is loaded in full into every session.

When invoked 1,984 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	$0.01984	$0.01984
Opus 5.5	$0.00794	$0.00794
Sonnet 5.5	$0.00397	$0.00397
Haiku 4.5	$0.00198	$0.00198

Measured 2mo ago against content hash 7d4429b5fa94, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

browser-operator-core CLAUDE.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 2mo 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.

CLAUDE.md · 207 lines

How it starts

The opening of the file, as written. The whole thing — 207 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Project Overview

Browser Operator is an AI-native browser built on Chrome DevTools frontend. It adds a multi-agent AI framework to the DevTools panel, enabling intelligent automation and web interaction through specialized AI agents.

Build & Development Commands

Initial Setup

# Prerequisites: depot_tools in PATH (https://chromium.googlesource.com/chromium/tools/depot_tools.git)
gclient sync
npm install
cp .env.example .env  # Configure API keys

Build

npm run build                    # Standard build (runs gn gen automatically)
npm run build -- --watch         # Watch mode for development
npm run build -- -t Debug        # Build to out/Debug instead of out/Default

# Fast build (skip type checking and bundling)
gn gen out/fast-build --args="devtools_skip_typecheck=true devtools_bundle=false"
npm run build -- -t fast-build

Running DevTools with Custom Build

# Terminal 1: Build with watch
npm run build -- --watch

# Terminal 2: Serve the built files
cd out/Default/gen/front_end && python3 -m http.server 9000

# Terminal 3: Launch Browser Operator with custom DevTools
/Applications/Browser\ Operator.app/Contents/MacOS/Browser\ Operator \
  --disable-infobars \
  --custom-devtools-frontend=http://localhost:9000/ \
  --remote-debugging-port=9222

Testing

npm run test                                      # Unit tests (Karma/Mocha)
npm run webtest                                   # E2E tests (Puppeteer)
npm run debug-webtest -- --spec=path/to/test     # Debug specific test
npm run lint                                      # ESLint

Eval Runner (Agent Testing)

Recommended: Use the eval-runner-analyst agent to run evals and get detailed analysis:

# In Claude Code, use the Task tool with eval-runner-analyst agent:
"Run the action agent evals with cerebras gpt-oss-120b"
"Test action-agent-checkbox-001 and action-agent-form-001"
"Compare V0 and V1 action agents on iframe tests"

Read the full file on GitHub · 207 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.

2mo ago First seen · 207 lines · 1,984 tokens per session scan A 7d4429b5fa94

Subscribe to this mod's changes

browser-operator-core CLAUDE.md is an instructions file published in the GitHub repository BrowserOperator/browser-operator-core (514 stars, last pushed 7mo ago), licensed BSD-3-Clause. It adds 1,984 tokens to every session, about $0.0079 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 2026-08-30.

LLM agent-workflow agentic-ai agents langgraph llamacpp

browser-operator-core CLAUDE.md next to 6 instructions from other repositories
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browser-operator-core: Instructions file for Claude Code