# browser-use SecurityWatchdog patch for real Comet profiles

browser-use 0.13.x closes existing `file://` tabs as "disallowed" on attach. This destroys the user's open local-file tabs in their real Comet profile.

## Patch (call before `BrowserSession.start()`)

```python
def patch_browser_use_security_watchdog():
    """Do not let browser-use close existing local/browser-scheme tabs on attach."""
    try:
        from browser_use.browser.watchdogs.security_watchdog import SecurityWatchdog
        if getattr(SecurityWatchdog, '_comet_agent_file_scheme_patch', False):
            return
        original = SecurityWatchdog._is_url_allowed
        def patched(self, url: str) -> bool:
            if isinstance(url, str) and url.startswith(('file://', 'chrome://', 'devtools://', 'edge://', 'comet://')):
                return True
            return original(self, url)
        SecurityWatchdog._is_url_allowed = patched
        SecurityWatchdog._comet_agent_file_scheme_patch = True
    except Exception as e:
        print(f'WARN: browser-use security patch skipped: {e}')
```

## Why it happens

`SecurityWatchdog.on_TabCreatedEvent` checks every tab URL against `_is_url_allowed`. When `allowed_domains` is None (default), `_is_url_allowed` allows `about:blank`, `chrome://new-tab-page/`, `chrome://newtab/`, `data:`, and `blob:` — but NOT `file://`. So any existing `file://` tabs in the real Comet profile get detected as "disallowed" and closed.

The patch adds `file://`, `chrome://`, `devtools://`, `edge://`, `comet://` to the allowlist.

## Alternative

Pass `allowed_domains=['*']` to `BrowserSession` — but this enables glob-pattern matching which has its own caveats. The monkeypatch is more surgical.