> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/derHaken/SuperAntigravity/llms.txt
> Use this file to discover all available pages before exploring further.

# Browser agent

> Delegates UI testing and browser automation to Antigravity's built-in browser subagent — with prerequisite checks and artifact requirements

Antigravity includes a built-in browser subagent that can interact with web applications autonomously. The browser-agent skill governs when and how to use it correctly: what prerequisites to check, how to frame requests precisely, and what artifacts prove a task is complete.

## When this skill fires

The skill description reads: *"Use when a task requires interacting with a web browser — testing UI flows, verifying web app behavior, clicking through screens, reading live web content, or automating browser workflows in Google Antigravity."*

Specific triggers:

* Testing a UI flow end-to-end (login, checkout, form submission)
* Verifying that a deployed or locally running web app behaves correctly after a code change
* Clicking through screens to confirm UI state
* Automating a repetitive browser workflow (fill form, submit, verify result)
* Reading live content from a specific URL that cannot be fetched as static text

**Do not use it for:**

* General web research (use `deep-research` instead)
* Fetching static API responses (use `curl` or fetch in terminal)
* Anything verifiable with a unit or integration test

## Prerequisites

Before any browser task, verify both conditions and state the result:

> "Chrome extension: \[installed / NOT installed] | Allowlist: \[domain confirmed / domain NOT listed]"

**1. Chrome extension installed**

* Look for the Chrome icon in Agent Manager (bottom left) or Editor (top right)
* Click it → follow the setup prompt → install from Chrome Web Store → grant permissions
* Without the extension, the browser agent cannot interact with pages

**2. URL allowlist configured** (for non-localhost URLs)

* Add trusted domains to `~/.gemini/antigravity/browserAllowlist.txt`, one per line:
  ```
  localhost
  127.0.0.1
  staging.myapp.com
  ```
* Add both `localhost` and `127.0.0.1` if the app may be accessed under either hostname

If either check fails, follow the error path before proceeding.

## How to frame browser requests

The browser agent responds to precise, stepwise instructions. Vague requests produce unreliable results.

**Bad:** "Test the login page"

**Good:** "Navigate to `http://localhost:3000/login`. Enter `test@example.com` in the email field and `password123` in the password field. Click the 'Sign In' button. Wait for navigation to complete. Verify the URL is now `http://localhost:3000/dashboard` and the text 'Welcome' appears on screen."

Every browser request must specify:

1. The starting URL
2. Each action in sequence (click X, type Y in Z, scroll to W)
3. The expected end state (URL, visible text, element present or absent)

<Tip>
  Prefer visible labels and text over CSS selectors — labels are more resilient to DOM changes. Use "Click the button labeled 'Submit'" rather than "Click button#submit-btn".
</Tip>

## Supported actions

| Action       | Example instruction                                                                          |
| ------------ | -------------------------------------------------------------------------------------------- |
| Navigate     | "Go to `http://localhost:3000/settings`"                                                     |
| Click        | "Click the button labeled 'Submit'"                                                          |
| Type         | "Type 'hello world' into the search input"                                                   |
| Scroll       | "Scroll down until the footer is visible"                                                    |
| Wait         | "Wait for the spinner to disappear"                                                          |
| Read DOM     | "Read the text content of the h1 element"                                                    |
| Screenshot   | "Take a screenshot of the current state"                                                     |
| Read console | "Check the browser console for errors"                                                       |
| Execute JS   | "Execute `document.title` and return the result" (read-only only — do not mutate auth state) |
| Record       | "Start recording before the first action; stop after the final step"                         |

## Completion requires an artifact

Do not claim a browser task is complete without a verifiable artifact.

**Acceptable:**

> "Browser task complete. Screenshot attached shows dashboard loaded at `/dashboard` with 'Welcome, Jane' visible. No console errors."

**Unacceptable:**

> "I think the login flow worked."

The completion checklist:

* [ ] Chrome extension was confirmed installed before starting
* [ ] URL(s) were confirmed in the allowlist before starting
* [ ] Each action step was executed in sequence
* [ ] The expected end state was verified (URL, visible text, element)
* [ ] At least one artifact (screenshot or recording) was produced
* [ ] Completion statement includes artifact reference and describes actual observed state

## Error paths

<Accordion title="Extension not installed">
  "Browser agent setup required. Open Agent Manager → click the Chrome icon → install the extension → retry."

  Do NOT proceed. The browser agent cannot function without the extension.
</Accordion>

<Accordion title="URL blocked by allowlist">
  "URL \[domain] is not in the allowlist. Add it to `~/.gemini/antigravity/browserAllowlist.txt` and retry."

  Do NOT attempt to bypass the allowlist.
</Accordion>

<Accordion title="Page does not reach expected state">
  1. Take a screenshot of the actual state
  2. Compare actual vs. expected
  3. Report the discrepancy with the screenshot as evidence
  4. Stop and surface the failure to the user — do NOT retry automatically without confirmation
</Accordion>

<Accordion title="Browser agent timeout">
  "Browser agent timed out. Simplify the request into smaller steps and retry once. If it times out again, stop and escalate to the user."
</Accordion>

## Example scenario

You ask: "Verify the login flow works on the local dev server."

The browser-agent skill fires. The agent:

1. Announces prerequisites: "Chrome extension: installed | Allowlist: `localhost` NOT listed — adding `localhost` and `127.0.0.1` now"
2. Adds both entries to `~/.gemini/antigravity/browserAllowlist.txt`
3. Delegates to browser agent with precise steps:
   * Navigate to `http://localhost:3000/login`
   * Type `admin@test.com` into the email field
   * Type `secret` into the password field
   * Click the submit button
   * Wait for URL to change
   * Take a screenshot
   * Verify URL is `/dashboard`, text "Welcome" is present, console has no errors
4. Produces artifact: screenshot of `/dashboard` state
5. Completion statement: "Login flow verified. Screenshot shows `/dashboard` with 'Welcome, Admin' heading. Zero console errors."

## Related skills

<CardGroup cols={2}>
  <Card title="Deep research" href="/skills/deep-research">
    For general web research — faster and more reliable than the browser agent for static information.
  </Card>

  <Card title="Verification before completion" href="/skills/verification-before-completion">
    Browser tasks require an artifact as evidence before any completion claim.
  </Card>
</CardGroup>