Use Browser

Use Browser

Token-efficient browser automation for coding agents, built on Microsoft's playwright-cli and defaulting to the Lightpanda headless browser. Instead of loading large tool schemas and verbose accessibility trees into context, you drive the browser through small CLI commands and read compact YAML snapshots.

Choosing a browser — read this first

Default to Lightpanda. Do not ask which browser to use.

The first time you need a browser in a task:

1. Ensure Lightpanda is installed. If lightpanda is not on PATH, run the bundled installer: scripts/install-lightpanda.sh (see references/lightpanda.md).

2. Ensure playwright-cli is available (playwright-cli --version, or npx --no-install playwright-cli --version). Install if missing — see Installing playwright-cli.

3. Start Lightpanda's CDP server (background) and attach to it:

   # background CDP server on ws://127.0.0.1:9222
   LIGHTPANDA_DISABLE_TELEMETRY=true lightpanda serve --host 127.0.0.1 --port 9222 &
   
   # point playwright-cli at the running Lightpanda
   playwright-cli attach --cdp=ws://127.0.0.1:9222
   

4. Drive the page normally (goto, snapshot, click, …). When done, playwright-cli close and stop the lightpanda serve process.

Switch browsers only when the user asks for a specific or "real" browser, or asks to choose. When they do, present the options and use playwright-cli open --browser=<name>:

When you do offer a choice and an interactive choice tool is available, use it with Lightpanda preselected as the recommended default; in other contexts ask in plain text. See references/browsers.md for the full decision guide and tradeoffs.

Fallback rule. Lightpanda is a fast but partial browser — some sites (heavy SPAs, certain TLS setups) will not render. If a Lightpanda goto/snapshot errors or times out (e.g. SslConnectError, navigation timeout, empty snapshot), tell the user it didn't render under Lightpanda and offer to fall back to Chromium (playwright-cli open --browser=chromium). Don't silently keep retrying Lightpanda.

Quick start

# default flow: drive Lightpanda over CDP
LIGHTPANDA_DISABLE_TELEMETRY=true lightpanda serve --host 127.0.0.1 --port 9222 &
playwright-cli attach --cdp=ws://127.0.0.1:9222
playwright-cli goto https://playwright.dev
# interact with the page using refs from the snapshot
playwright-cli click e15
playwright-cli type "page.click"
playwright-cli press Enter
# take a screenshot (rarely used — the snapshot is more common)
playwright-cli screenshot
playwright-cli close

If the user asked for a full browser instead, replace the first two lines with a single playwright-cli open (optionally with --browser=<name>).

Commands

Core

playwright-cli open
# open and navigate right away
playwright-cli open https://example.com/
playwright-cli goto https://playwright.dev
playwright-cli type "search query"
playwright-cli click e3
playwright-cli dblclick e7
# --submit presses Enter after filling the element
playwright-cli fill e5 "user@example.com" --submit
playwright-cli drag e2 e8
# drop files or data onto an element (from outside the page)
playwright-cli drop e4 --path=./image.png
playwright-cli drop e4 --data="text/plain=hello world"
playwright-cli hover e4
playwright-cli select e9 "option-value"
playwright-cli upload ./document.pdf
playwright-cli check e12
playwright-cli uncheck e12
playwright-cli snapshot
playwright-cli eval "document.title"
playwright-cli eval "el => el.textContent" e5
# get element id, class, or any attribute not visible in the snapshot
playwright-cli eval "el => el.id" e5
playwright-cli eval "el => el.getAttribute('data-testid')" e5
playwright-cli dialog-accept
playwright-cli dialog-accept "confirmation text"
playwright-cli dialog-dismiss
playwright-cli resize 1920 1080
playwright-cli close

Navigation

playwright-cli go-back
playwright-cli go-forward
playwright-cli reload

Keyboard

playwright-cli press Enter
playwright-cli press ArrowDown
playwright-cli keydown Shift
playwright-cli keyup Shift

Mouse

playwright-cli mousemove 150 300
playwright-cli mousedown
playwright-cli mousedown right
playwright-cli mouseup
playwright-cli mouseup right
playwright-cli mousewheel 0 100

Save as

playwright-cli screenshot
playwright-cli screenshot e5
playwright-cli screenshot --filename=page.png
playwright-cli pdf --filename=page.pdf

Tabs

playwright-cli tab-list
playwright-cli tab-new
playwright-cli tab-new https://example.com/page
playwright-cli tab-close
playwright-cli tab-close 2
playwright-cli tab-select 0

Storage

playwright-cli state-save
playwright-cli state-save auth.json
playwright-cli state-load auth.json

# Cookies
playwright-cli cookie-list
playwright-cli cookie-list --domain=example.com
playwright-cli cookie-get session_id
playwright-cli cookie-set session_id abc123
playwright-cli cookie-set session_id abc123 --domain=example.com --httpOnly --secure
playwright-cli cookie-delete session_id
playwright-cli cookie-clear

# LocalStorage
playwright-cli localstorage-list
playwright-cli localstorage-get theme
playwright-cli localstorage-set theme dark
playwright-cli localstorage-delete theme
playwright-cli localstorage-clear

# SessionStorage
playwright-cli sessionstorage-list
playwright-cli sessionstorage-get step
playwright-cli sessionstorage-set step 3
playwright-cli sessionstorage-delete step
playwright-cli sessionstorage-clear

More: references/storage-state.md.

Network

playwright-cli route "**/*.jpg" --status=404
playwright-cli route "https://api.example.com/**" --body='{"mock": true}'
playwright-cli route-list
playwright-cli unroute "**/*.jpg"
playwright-cli unroute

More: references/request-mocking.md.

DevTools

playwright-cli console
playwright-cli console warning
playwright-cli requests
playwright-cli request 5
playwright-cli run-code "async page => await page.context().grantPermissions(['geolocation'])"
playwright-cli run-code --filename=script.js
playwright-cli tracing-start
playwright-cli tracing-stop
playwright-cli video-start video.webm
playwright-cli video-chapter "Chapter Title" --description="Details" --duration=2000
playwright-cli video-stop

# annotate each subsequent action with a callout naming it and highlighting the target
playwright-cli video-show-actions --duration=600 --position=top-right
playwright-cli video-hide-actions

# launch the dashboard for UI review / design feedback
playwright-cli show --annotate

# generate a Playwright locator for an element from its ref or selector
playwright-cli generate-locator e5 --raw

# persistent highlight overlay for an element, optionally with custom style
playwright-cli highlight e5
playwright-cli highlight e5 --style="outline: 3px dashed red"
playwright-cli highlight e5 --hide
playwright-cli highlight --hide

Raw output

The global --raw option strips page status, generated code, and snapshot sections from the output, returning only the result value. Use it to pipe command output into other tools. Commands that don't produce output return nothing.

playwright-cli --raw eval "JSON.stringify(performance.timing)" | jq '.loadEventEnd - .navigationStart'
playwright-cli --raw eval "JSON.stringify([...document.querySelectorAll('a')].map(a => a.href))" > links.json
playwright-cli --raw snapshot > before.yml
playwright-cli click e5
playwright-cli --raw snapshot > after.yml
diff before.yml after.yml
TOKEN=$(playwright-cli --raw cookie-get session_id)
playwright-cli --raw localstorage-get theme

For structured output wrapping every reply as JSON, pass --json:

playwright-cli list --json

Open / attach parameters

# DEFAULT browser is Lightpanda over CDP — prefer attach (see top of file):
LIGHTPANDA_DISABLE_TELEMETRY=true lightpanda serve --host 127.0.0.1 --port 9222 &
playwright-cli attach --cdp=ws://127.0.0.1:9222

# Connect to any running browser via a CDP endpoint
playwright-cli attach --cdp=http://localhost:9222
# Connect to a running Chrome or Edge by channel name
playwright-cli attach --cdp=chrome
playwright-cli attach --cdp=msedge
# Connect via the Playwright browser extension
playwright-cli attach --extension=chrome

# Full browsers (only when the user asks for one):
playwright-cli open --browser=chromium
playwright-cli open --browser=chrome
playwright-cli open --browser=firefox
playwright-cli open --browser=webkit
playwright-cli open --browser=msedge

# Persistent profile (by default the profile is in-memory)
playwright-cli open --persistent
playwright-cli open --profile=/path/to/profile

# Start with a config file
playwright-cli open --config=my-config.json

# Close / detach / delete
playwright-cli close
# detach leaves an attached external browser (e.g. Lightpanda) running
playwright-cli -s=default detach
playwright-cli delete-data

Snapshots

After each command, playwright-cli provides a snapshot of the current browser state.

> playwright-cli goto https://example.com
### Page
- Page URL: https://example.com/
- Page Title: Example Domain
### Snapshot
Snapshot: `.playwright-cli/page-2026-02-14T19-22-42-679Z.yml`

You can take a snapshot on demand; options combine freely.

playwright-cli snapshot                         # timestamped file
playwright-cli snapshot --filename=after-click.yaml
playwright-cli snapshot "#main"                 # element subtree
playwright-cli snapshot --depth=4               # limit depth
playwright-cli snapshot e34                      # subtree of a ref
playwright-cli snapshot --boxes                  # include [box=x,y,width,height]

Targeting elements

By default, use refs from the snapshot to interact with page elements.

playwright-cli snapshot       # get refs (e3, e15, …)
playwright-cli click e15

CSS selectors and Playwright locators also work:

playwright-cli click "#main > button.submit"
playwright-cli click "getByRole('button', { name: 'Submit' })"
playwright-cli click "getByTestId('submit-button')"

Reading attributes not shown in the snapshot: references/element-attributes.md.

Browser sessions

# named session with persistent profile
playwright-cli -s=mysession open example.com --persistent
playwright-cli -s=mysession click e6
playwright-cli -s=mysession close
playwright-cli -s=mysession delete-data

playwright-cli list           # list sessions
playwright-cli close-all       # close all browsers
playwright-cli kill-all        # force-kill all browser processes

More: references/session-management.md.

Installing playwright-cli

If a project-local copy exists, prefer it:

npx --no-install playwright-cli --version

Otherwise install globally:

npm install -g @playwright/cli@latest

For installing the Lightpanda browser, see references/lightpanda.md or run the bundled scripts/install-lightpanda.sh.

Examples

# Form submission (Lightpanda default)
lightpanda serve --host 127.0.0.1 --port 9222 &
playwright-cli attach --cdp=ws://127.0.0.1:9222
playwright-cli goto https://example.com/form
playwright-cli snapshot
playwright-cli fill e1 "user@example.com"
playwright-cli fill e2 "password123"
playwright-cli click e3
playwright-cli snapshot
playwright-cli close

# Debugging with DevTools
playwright-cli goto https://example.com
playwright-cli tracing-start
playwright-cli click e4
playwright-cli fill e7 "test"
playwright-cli console
playwright-cli requests
playwright-cli tracing-stop
playwright-cli close

Specific tasks

• Choosing / switching browsers, Lightpanda vs full browsers references/browsers.md
• Lightpanda: install, serve, attach, limits references/lightpanda.md
• Running and debugging Playwright tests references/playwright-tests.md
• Request mocking references/request-mocking.md
• Running Playwright code references/running-code.md
• Browser session management references/session-management.md
• Spec-driven testing (plan / generate / heal) references/spec-driven-testing.md
• Storage state (cookies, localStorage) references/storage-state.md
• Test generation references/test-generation.md
• Tracing references/tracing.md
• Video recording references/video-recording.md
• Inspecting element attributes references/element-attributes.md

The playwright-cli command reference and the references/*.md files marked above (all except browsers.md and lightpanda.md) are adapted from Microsoft's playwright-cli project, used under the Apache-2.0 license. See NOTICE.