Naven
Glossary
Username
A short handle that identifies an account without revealing an email address or phone number.
A username lets somebody be contacted without handing over a permanent personal identifier. Unlike a phone number it can be changed, and unlike an email address it is not also a login on forty other sites.
The design question is whether usernames are searchable. Exact-match only is a meaningful safety property.
Where Naven stands
Naven usernames match exactly, never by prefix or by name, and a personal link built from one starts a conversation rather than granting anything.