I need to know if the customer has successfully logged in or logged out in the current request. I need to do it in a After plugin (after execute of LogIn and Logout from customer) How can I check it? Is there something in request I could get and compare with data in login's logout's afterExecute? I though about formkey, but I'm not 100% sure it changes when user toggle between login and logout.
Update (Clarifying the question):
I'm developing a module for login and logout using AJAX but I don't want to reload the page in any moment, this is why I need to add a extra piece of HTML, this HTML is the header links (that first menu in Luma theme, with Register and login when are not logged, and account, address, wishlist etc when logged). Once the menu changes when toggled between login and logout I need to update it (in my case replace the whole menu).
So I created a after plugin used for both actions in customer module: Login and Logout, once they do the same thing I use same plugin for both action (but it doesn't matter). The login may fail so I don't need to updated the menu, then I don't want to send HTML attached to answer unnecessarily, this is why I need to know if the customer was logged out and now logged in and vice-versa.