Invalid url for valid usernames

[danbulant]

According to specification 4.3.1, a single / is a valid localpart for a user identifier.

Matrix.to shows that I can use @localpart:domain, and in fact @name:host does work, but writing @/:domain only shows "invalid URL" dialog - even when I explicitly write it in the text field and press "Create link", which I think is bad UX (should say that the name is invalid).

Also, according to the matrix specification 4.3.1.1, clients MUST accept localparts that have any ASCII printing characters except :.

[AsbjornOlling]

Room aliases containing / are also rejected.
#288