Hey @andrew ! A feature request for you.
Right now the only way to add contributors to a universe is via the email address they used to create their Notebook account. However sometimes I have contributors that I feel uncomfortable asking for that kind of personal information from them. Notebook is designed to be private from jump and some people use email with their real names so I always feel awkward asking if I don't know them very well, you know?
Would it be possible to add contributors some other way? I was thinking via an invite link or referral code a la Discord style - you could make them one-use only or expire them or whatnot - or if you know their Notebook username already, add them via that username? Just something other than their personal email.