In Tracker comments, you can ping somebody by simply doing @username. The problem is you must be aware about this. Something like autocompleter poping up after typing @ would be nice, similar how it works here on Phabricator.
|Resolved||Nathan_fraignt||T206603 Allow normal user to do things they are allowed to do in frontend in API as well|
|Open||takidelfin||T210565 Implement autocompleted feature for comments mentions|