[[mw:Extension:OAuth]] prompts a user to authorize an app at a URL similar to https://www.mediawiki.org/w/index.php?title=Special:MWOAuth/authorize&oauth_token=0cd1232bf697849cedc5d95f77d61144&oauth_consumer_key=f26337df9e626952ba65123be86f8e62.
This prompt looks like this:
Gerrit Patch Uploader would like to have basic access on your behalf on www.mediawiki.org.
This may be an issue for the WikimediaMessages extension. I'm not sure.