Skill: Chrome Automation (agent-browser)

Automate browser tasks in the user's real Chrome session via the agent-browser CLI.

Prerequisite: agent-browser must be installed and Chrome must have remote debugging enabled. See references/agent-browser-setup.md if unsure.

Core Principle: Reuse the User's Existing Chrome

This skill operates on a single Chrome process — the user's real browser. There is no session management, no separate profiles, no launching a fresh Playwright browser.

Always Start by Listing Tabs

Before opening any new page, always list existing tabs first:

agent-browser --auto-connect tab list

This returns all open tabs with their index numbers, titles, and URLs. Check if the page you need is already open:

• If the target page is already open → switch to that tab directly instead of opening a new one. The user likely has it open because they are already logged in and the page is in the right state.

  agent-browser --auto-connect tab <index>
  

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• If the target page is NOT open → open it in the current tab or a new tab.

  agent-browser --auto-connect open <url>
  

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Why This Matters

• The user's Chrome has their cookies, login sessions, and browser state
• Opening a new page when one is already available wastes time and may lose login state
• Many marketing platforms (social media dashboards, ad managers, CMS tools) require login — reusing an existing logged-in tab avoids re-authentication

Connection

Always use --auto-connect to connect to the user's running Chrome instance:

agent-browser --auto-connect <command>

This auto-discovers Chrome with remote debugging enabled. If connection fails, guide the user through enabling remote debugging (see references/agent-browser-setup.md).

Chrome 144+ WebSocket-Only Fallback

Chrome 144+ can expose remote debugging from chrome://inspect/#remote-debugging as a WebSocket-only endpoint. In that state the page shows Server running at: 127.0.0.1:9222, but the traditional discovery URLs return 404:

curl http://127.0.0.1:9222/json/version
curl http://127.0.0.1:9222/json/list

Older agent-browser versions such as 0.27.x may fail with No running Chrome instance found even though Chrome is ready. First try the latest CLI without changing the global install:

npx -y agent-browser@latest connect "ws://127.0.0.1:9222/devtools/browser"
npx -y agent-browser@latest tab list

If this works, use npx -y agent-browser@latest <command> for the rest of the browser task. If it fails with an engine warning or install error, upgrade Node to 24+ or install the latest agent-browser globally.

Common Workflows

1. Navigate and Interact

# List tabs to find existing pages
agent-browser --auto-connect tab list

# Switch to an existing tab (if found)
agent-browser --auto-connect tab <index>

# Or open a new page
agent-browser --auto-connect open https://example.com
agent-browser --auto-connect wait --load networkidle

# Take a snapshot to see interactive elements
agent-browser --auto-connect snapshot -i

# Click, fill, etc.
agent-browser --auto-connect click @e3
agent-browser --auto-connect fill @e5 "some text"

2. Extract Data from a Page

# Get all text content
agent-browser --auto-connect get text body

# Take a screenshot for visual inspection
agent-browser --auto-connect screenshot

# Execute JavaScript for structured data
agent-browser --auto-connect eval "JSON.stringify(document.querySelectorAll('table tr').length)"

3. Replay a Chrome DevTools Recording

The user may provide a recording exported from Chrome DevTools Recorder (JSON, Puppeteer JS, or @puppeteer/replay JS format). See Replaying Recordings below.

Step-by-Step Interaction Guide

Taking Snapshots

Use snapshot -i to see all interactive elements with refs (@e1, @e2, ...):

agent-browser --auto-connect snapshot -i

The output lists each interactive element with its role, text, and ref. Use these refs for subsequent actions.

Step Type Mapping

How to Distinguish Input Types

• Standard input/textarea → use fill
• Contenteditable div / rich text editor (LinkedIn message box, Gmail compose, Slack, CMS editors) → click/focus first, then use keyboard inserttext

Ref Lifecycle

Refs (@e1, @e2, ...) are invalidated when the page changes. Always re-snapshot after:

• Clicking links or buttons that trigger navigation
• Submitting forms
• Triggering dynamic content loads (AJAX, SPA navigation)

Verification

After each significant action, verify the result:

agent-browser --auto-connect snapshot -i   # check interactive state
agent-browser --auto-connect screenshot     # visual verification

Replaying Recordings

Accepted Formats

1. JSON (recommended) — structured, can be read progressively:

   # Count steps
   jq '.steps | length' recording.json
   
   # Read first 5 steps
   jq '.steps[0:5]' recording.json
   

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2. @puppeteer/replay JS (import { createRunner })

3. Puppeteer JS (require('puppeteer'), page.goto, Locator.race)

How to Replay

1. Parse the recording — understand the full intent before acting. Summarize what the recording does.
2. List tabs first — check if the target page is already open.
3. Navigate — execute navigate steps, reusing existing tabs when possible.
4. For each interaction step:
   • Take a snapshot (snapshot -i) to see current interactive elements
   • Match the recording's aria/... selectors against the snapshot
   • Fall back to text/..., then CSS class hints, then screenshot
   • Do not rely on ember IDs, numeric IDs, or exact XPaths — these change every page load
5. Verify after each step — snapshot or screenshot to confirm

Iframe-Heavy Sites

snapshot -i operates on the main frame only and cannot penetrate iframes. Sites like LinkedIn, Gmail, and embedded editors render content inside iframes.

Detecting Iframe Issues

• snapshot -i returns unexpectedly short or empty results
• Recording references elements not appearing in snapshot output
• get text body content doesn't match what a screenshot shows

Workarounds

1. Use eval to access iframe content:

   agent-browser --auto-connect eval --stdin <<'EVALEOF'
   const frame = document.querySelector('iframe[data-testid="interop-iframe"]');
   const doc = frame.contentDocument;
   const btn = doc.querySelector('button[aria-label="Send"]');
   btn.click();
   EVALEOF
   

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   Note: Only works for same-origin iframes.

2. Use keyboard for blind input: If the iframe element has focus, keyboard inserttext "..." sends text regardless of frame boundaries.

3. Use get text body to read full page content including iframes.

4. Use screenshot for visual verification when snapshot is unreliable.

When to Ask the User

If workarounds fail after 2 attempts on the same step, pause and explain:

• The page uses iframes that cannot be accessed via snapshot
• Which element you need and what you expected
• Ask the user to perform that step manually, then continue

Handling Unexpected Situations

Handle Automatically (do not stop):

• Popups or banners → dismiss them (find text "Dismiss" click or find text "Close" click)
• Cookie consent dialogs → accept or dismiss
• Tooltip overlays → close them first
• Element not in snapshot → try find text "..." click, or scroll to reveal with scroll down 300

Pause and Ask the User:

• Login / authentication is required
• A CAPTCHA appears
• Page structure is completely different from expected
• A destructive action is about to happen (deleting data, sending real content) — confirm first
• Stuck for more than 2 attempts on the same step
• All iframe workarounds have failed

When pausing, explain clearly: what step you are on, what you expected, and what you see.

Key Commands Reference

Known Limitations

1. Iframe blindness: snapshot -i cannot see inside iframes. See Iframe-Heavy Sites.
2. find text strict mode: Fails when multiple elements match. Use snapshot -i to locate the specific ref instead.
3. fill vs contenteditable: fill only works on <input> and <textarea>. For rich text editors, use keyboard inserttext.
4. eval is main-frame only: To interact with iframe content, traverse via document.querySelector('iframe').contentDocument...

Multi-Platform Operations

When the user requests an action across multiple platforms (e.g., "publish this article to Dev.to, LinkedIn, and X"), do NOT attempt all platforms in a single conversation. Instead, launch sequential subagents/workers, one per platform. Selecting this skill is explicit permission to use subagents/workers for this multi-platform workflow.

Why Subagents

Each platform operation consumes ~25-40K tokens (reference file + snapshots + interactions). Running 3-5 platforms in one context risks hitting the context limit and degrading late-platform accuracy. Each subagent/worker gets its own fresh context window.

How to Execute

1. Prepare the content — confirm the post text, title, tags, and any platform-specific adaptations with the user.
2. For each platform, launch a subagent/worker with a prompt that includes:
   • The full content to publish
   • Instructions to read the relevant reference file (e.g., Read /path/to/skills/chrome-automation/references/x.md)
   • Instructions to read the agent-browser skill file for command reference
   • The specific task (post, comment, reply, etc.)
   • Any platform-specific instructions (e.g., "use these hashtags on LinkedIn")
3. Run subagents/workers sequentially (one at a time), because they all share the same Chrome browser via --auto-connect. Parallel subagents/workers would cause tab conflicts.
4. After each subagent/worker completes, report the result to the user before launching the next one.

Prompt Template for Subagents

You are automating a browser task on [PLATFORM].

First, read these files for context:
- /absolute/path/to/skills/chrome-automation/references/[platform].md
- The installed agent-browser skill file, if available (agent-browser command reference)

Then connect to the user's Chrome browser using `agent-browser --auto-connect` and perform the following task:

[TASK DESCRIPTION]

Content to publish:
[CONTENT]

Important:
- Always list tabs first (`tab list`) and reuse existing logged-in tabs
- Re-snapshot after every navigation or action
- Confirm with the user before submitting/publishing (destructive action)
- If login is required or a CAPTCHA appears, stop and explain

When NOT to Use Subagents

• Single platform — just do it directly in the current conversation.
• Read-only tasks (browsing, searching, extracting data) — context usage is lighter; a single conversation can handle 2-3 platforms.

Platform References

When automating tasks on specific platforms, consult the relevant reference document for page structure details, common operations, and known quirks:

For installation and Chrome setup instructions, see references/agent-browser-setup.md.