Review fixes for the sign-in window:
- Each sign-in has a random attempt id. Closing, timing out or signing out
stops cookie intake first, then tells the server (new cancel-signin action)
not to save a connect from that attempt, even one still waiting on Meta
(frame_meta.connect/cancel_signin; 409 from the server). Disconnect signs
out of the window before deleting the token.
- will-frame-navigate holds every frame to the allow-list; a frame going
elsewhere is stopped, never opened outside.
- The window is destroyed, not closed, and will-prevent-unload is overridden,
so beforeunload can't keep it alive; sign-out clears the session only after
the window is gone.
- Permission checks refused as well as requests; no developer tools.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
