I’m going through the same situation.
the following works fine with me (wiki as a sub directory inside wordpress)
example.com -> wordpress site
example.com/wiki
but what I’m trying to do now is something like this
example.com
wiki.example.com
but authorization with wordpress user in the mediawiki is not working,
checking if the wordpress user is logged in from the WPMW extension always give not logged in.
I think it’s cookies issue but I can’t figure how to fix it and from which side.
