WordPress.com VIP platform specific
This document is for sites running on WordPress.com VIP.
Users logged in to WordPress.com benefit from platform-wide features such as automatic login on any website hosted on the platform, including VIP websites hosted on WordPress.com.
In the case where a user logged in to WordPress.com lands on a site with a mapped domain and hits Batcache without the necessary cookies, a JS file sends the browser to
wordpress.com/remote-login.php where their logged in/out status is checked. If the user is logged in to WordPress.com, then they are redirected back to the mapped domain where the cookie is logged, and then redirected back to the page in the original request (where the user should now see the admin bar, which confirms their logged in status).
This happens only once, as long as the user does not clear their cookies. It also may happen when the browser is closed.