Implement karma
There's an interesting problem. If a user mentions explicitly another user using autocomplete, it'll use a special form of mention which contains the full sender's name, including its originating Matrix server. But people may also just use the Bugzilla nick name or something else.
for instance for me, people could either say [email protected]++ or bnjbvr++ (or even with a different former nick that i used).
So now we have a possible problem of duplicating entries for a single entry.
We could try to deduplicate smartly, that is, if the nick's part of a Matrix sender is unique in this room, consider this to be equal to just the sender's nick (that is, [email protected] is just bnjbvr). That's a bit fragile though, because then a new user with the same nick in the same room would get this karma too, or break the deduplication system (leading to forgotten karma, an unforgivable crime).
We could also maintain a manual list of entries to associate karma between the Matrix nick and regular nick. That's a lot of work to manually maintain such a mapping for a low value, so no let's not do that.
Or let it go and live with the duplication...