The threads view shows a list of threads the user is participating in, ordered by the last activity inside the thread (most recently active shows at the bottom). Participation happens when one of these conditions is met:

• The thread was created on a message posted by the user.
• The user commented inside the thread.
• The user was mentioned inside a thread.
• The thread was created in a room that the user has starred.

The issue is that it's hard to know which threads you're participating in have unread comments. In the regular chat rooms, unreads are defined by timestamp, so you can have read everything until a certain time and everything beyond that time is unread. But this doesn't work for the threads view because you could have read everything in a recent thread and have unread comments in an older thread.

As a first iteration, we should make the "Last reply [timestamp]" bold and black (just like the timestamps in the sidebar) when there's unread activity inside a thread. This should show both in the threads view as well as in other places where the parent message is show. It should only show like that to participating users though (based on criteria above). For users who are not participating, the last reply timestamp shouldn't show any unread status.