Issues with referencing users - login using oath?

I have discovered an issue with handling users logged in with oath.

My oauth log in has an ldap backend. The user details are defined by username, email, displayname.

It is the display name that is displayed in misago as the username. The display name can be "Firstname Lastname". Misago interprets this as "Firstname_Lastname".

If I go to try to initiate a private message with such a user the "start thread" button remains greyed out. I cannot add such a user to an existing private discussion. I also cannot successfully refer to such a user using @username. Yet the user exists in the site displayed as "Firstname_Lastname"

As an aside to this, what would happen in misago if a user changed their displayname in the ldap database backing the oauth to be the same as a user with the same displayname?

I can mitigate against this by making change of displayname an admin function, but I would prefer to allow users to be able to change their displayname. But I envisage problems.

Yes. This is tested as working and does prevent a possible spoofing behaviour of malicious users.

I've lightly tested this, and it seems to have solved the issue. I can now invite users with an underscore to private messages.

Thank you very much. Excellent work.