agent-browser

Files (11)

• SKILL.md
• authentication.md · references/
• commands.md · references/
• profiling.md · references/
• proxy-support.md · references/
• session-management.md · references/
• snapshot-refs.md · references/
• video-recording.md · references/
• authenticated-session.sh · templates/
• capture-workflow.sh · templates/
• form-automation.sh · templates/

SKILL.md (first lines)

# [accessibility tree]
# --- END_AGENT_BROWSER_PAGE_CONTENT nonce=<hex> ---
```

### Domain Allowlist

Restrict navigation to trusted domains. Wildcards like `*.example.com` also match the bare domain `example.com`. Sub-resource requests, WebSocket, and EventSource connections to non-allowed domains are also blocked. Include CDN domains your target pages depend on:

```bash
export AGENT_BROWSER_ALLOWED_DOMAINS="example.com,*.example.com"
agent-browser open https://example.com        # OK
agent-browser open https://malicious.com       # Blocked
```

### Action Policy

Use a policy file to gate destructive actions:

```bash
export AGENT_BROWSER_ACTION_POLICY=./policy.json
```

Example `policy.json`:
```json
{"default": "deny", "allow": ["navigate", "snapshot", "click", "scroll", "wait", "get"]}
```

Auth vault operations (`auth login`, etc.) bypass action policy but domain allowlist still applies.

### Output Limits

Prevent context flooding from large pages:

```bash
export AGENT_BROWSER_MAX_OUTPUT=50000
```

## Diffing (Verifying Changes)

Use `diff snapshot` after performing an action to verify it had the intended effect. This compares the current accessibility tree against the last snapshot taken in the session.

```bash
# Typical workflow: snapshot -> action -> diff
agent-browser snapshot -i          # Take baseline snapshot
agent-browser click @e2            # Perform action
agent-browser diff snapshot        # See what changed (auto-compares to last snapshot)
```

For visual regression testing or monitoring:

```bash
# Save a baseline screenshot, then compare later
agent-browser screenshot baseline.png
# ... time passes or changes are made ...
agent-browser diff screenshot --baseline baseline.png

# Compare staging vs production
agent-browser diff url https://staging.example.com https://prod.example.com --screenshot
```

`diff snapshot` output uses `+` for additions and `-` for removals, similar to git diff. `diff screenshot` produces a diff image with changed pixels highlighted in red, plus a mismatch percentage.

## Timeouts and Slow Pages

The default Playwright timeout is 25 seconds for local browsers. This can be overridden with the `AGENT_BROWSER_DEFAULT_TIMEOUT` environment variable (value in milliseconds). For slow websites or large pages, use explicit waits instead of relying on the default timeout:

```bash
# Wait for network activity to settle (best for slow pages)
agent-browser wait --load networkidle

# Wait for a specific element to appear
agent-browser wait "#content"
agent-browser wait @e1

# Wait for a specific URL pattern (useful after redirects)
agent-browser wait --url "**/dashboard"

# Wait for a JavaScript condition
agent-browser wait --fn "document.readyState === 'complete'"

# Wait a fixed duration (milliseconds) as a last resort
agent-browser wait 5000
```

When dealing with consistently slow websites, use `wait --load networkidle` after `open` to ensure the page is fully loaded before taking a snapshot. If a specific element is slow to render, wait for it directly with `wait <selector>` or `wait @ref`.

## Session Management and Cleanup

When running multiple agents or automations concurrently, always use named sessions to avoid conflicts:

```bash
# Each agent gets its own isolated session
agent-browser --session agent1 open site-a.com
agent-browser --session agent2 open site-b.com

# Check active sessions
agent-browser session list
```

Always close your browser session when done to avoid leaked processes:

```bash
agent-browser close                    # Close default session
agent-browser --session agent1 close   # Close specific session
```

If a previous session was not closed properly, the daemon may still be running. Use `agent-browser close` to clean it up before starting new work.

## Ref Lifecycle (Important)

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

- Clicking links or buttons that navigate
- Form submissions
- Dynamic content loading (dropdowns, modals)

```bash
agent-browser click @e5              # Navigates to new page
agent-browser snapshot -i            # MUST re-snapshot
agent-browser click @e1              # Use new refs

From mkurman/zorai, MIT.

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