dev-browser

A browser-automation skill that keeps the state of a web page between actions. It can navigate sites, interact with controls, read page data, inspect accessibility information, and take screenshots.

In plain words
What is it for?
Use it to visit websites, fill in forms, click buttons, extract information, test web applications, and capture screenshots.
Why use it?
It removes the need to perform repeated browser steps by hand and helps the agent work with pages whose layout or controls are not known in advance.

Skill for Claude CodeCodex

Install

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.

agentmods
npx agentmods add skills/memtensor/memos/dev-browser
Any agent
npx skills add MemTensor/MemOS --skill dev-browser
Clone the repo
git clone --depth 1 https://github.com/MemTensor/MemOS

Made for: Claude Code, Codex.

Per session 84 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,616 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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.

ModelPer sessionOnce invoked
Fable 5 $0.00084 $0.01616
Opus 5 $0.00042 $0.00808
Sonnet 5 $0.00017 $0.00323
Haiku 4.5 $0.00008 $0.00162

Measured yesterday against content hash 3f04e81004ba, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

dev-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 yesterday.

The scan reads SKILL.md. This mod also ships 12 executable files (scripts/start-relay.ts, scripts/start-server.ts, server.sh, …), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

Origin

Copies of this mod

2 near-identical copies found in the catalogue:

apps/openwork-memos-integration/apps/desktop/skills/dev-browser/SKILL.md · 212 lines

How it starts

The opening of the file, as written. The whole thing — 212 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Dev Browser Skill

Browser automation that maintains page state across script executions. Write small, focused scripts to accomplish tasks incrementally. Once you've proven out part of a workflow and there is repeated work to be done, you can write a script to do the repeated work in a single execution.

Choosing Your Approach

  • Local/source-available sites: Read the source code first to write selectors directly
  • Unknown page layouts: Use getAISnapshot() to discover elements and selectSnapshotRef() to interact with them
  • Visual feedback: Take screenshots to see what the user sees

Setup

Two modes available. Ask the user if unclear which to use.

Standalone Mode (Default)

Launches a new Chromium browser for fresh automation sessions.

./skills/dev-browser/server.sh &

Add --headless flag if user requests it. Wait for the Ready message before running scripts.

Extension Mode

Connects to user's existing Chrome browser. Use this when:

  • The user is already logged into sites and wants you to do things behind an authed experience that isn't local dev.
  • The user asks you to use the extension

Important: The core flow is still the same. You create named pages inside of their browser.

Start the relay server:

cd skills/dev-browser && npm i && npm run start-extension &

Wait for Waiting for extension to connect... followed by Extension connected in the console. To know that a client has connected and the browser is ready to be controlled. Workflow:

  1. Scripts call client.page("name") just like the normal mode to create new pages / connect to existing ones.
  2. Automation runs on the user's actual browser session

If the extension hasn't connected yet, tell the user to launch and activate it. Download link: https://github.com/SawyerHood/dev-browser/releases

Writing Scripts

Run all scripts from skills/dev-browser/ directory. The @/ import alias requires this directory's config.

Read the full file on GitHub · 212 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.

  1. yesterday First seen · 212 lines · 84 tokens per session scan A 3f04e81004ba

Subscribe to this mod's changes

dev-browser is a skill published in the GitHub repository MemTensor/MemOS (11,091 stars, last pushed 4d ago), licensed Apache-2.0. It adds 84 tokens to every session and 1,616 once invoked, about $0.0004 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 2026-08-30.

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