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Local only

  • The companion binds to 127.0.0.1. There is no cloud component, no telemetry and no account.
  • The extension talks only to that port and only after presenting the pairing token.
  • Messages from the extension to the companion are validated; malformed frames are rejected and the socket closed.

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Access is opt-in per tab

The agent reaches exactly the tabs you share, plus tabs it opened itself in your window. chrome:// pages, extension pages and the Web Store are never automatable. Emergency stop revokes everything at once.

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What the agent can see in a shared tab

Everything the page can: DOM, cookies for the page origin, local and session storage, network requests and their bodies while a devtools_session is running, and JavaScript evaluation in the page. Treat a shared tab as fully visible to the agent. Do not share tabs you would not paste into the chat.

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Restricting what the agent does

  • Disable tools you do not want used.
  • Domain policies limit where a tab, or every tab the agent opens, may navigate and load resources from.
  • Set the developer browser to Never if the agent should not get a second browser.
  • The activity log is off by default and keeps nothing; on, it holds the last 200 commands in memory only, never on disk. See Activity.

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Secrets

  • The pairing token is in ~/.browspark/token with mode 0600 and in the extension’s local storage. It appears in the HTTP endpoint URL and live-view URLs; treat those like passwords.
  • Recorder exports and HAR files can contain form values, cookies and headers. They are written to ~/.browspark/artifacts or the path you give.
  • Developer-context profiles under ~/.browspark/ hold logins like any Chrome profile.

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The debugger permission

Chrome grants the extension the debugger permission at install time. The extension attaches only to shared tabs, only when a command arrives, and detaches after 30 seconds of inactivity. The yellow bar Chrome shows is the honest signal that a tab is attached.