OurBigBook
Currently on web:
<@user-name>produces a working link, but with bad title "index"<#some-topic>fails
What we want to work is either of:
@user-name#some-topic<#some topic>
Perfect topic rendering can be a bit trick because it might require fetching actual topic from DB to see its preferred title.
At mentions ideally bring the side-effect of notifications, but then we have to think about spam a bit too.