[somat]

For me at least the whole thing could be solved with a change to the cookie management panel. Let me mark cookies(domains) I want to keep, stuff where I do want to stay logged in, and then set it to clear all unmarked cookies at the end of the session.

[retrodaredevil]

I use this extension to do just that: https://addons.mozilla.org/en-US/firefox/addon/cookie-autode...