Replies do not populate form with @mentions

When you reply to a post on the Fediverse a notification is sent to the author of that post. If you are in a thread/conversation and reply to a post with several people in it, typically you will find several accounts being mentioned:

This allows everyone in the conversation to receive a notification for your reply. However, in FediFE these accounts are not automatically populated into the field.

From a UX standpoint I hate this because it's ugly and wastes a lot of space, especially on mobile with the full length @user@domain, but we don't have a solution here yet. It's really a compatibility issue across the Fediverse, but I'd like us to find a way to lead the way in fixing it. That's really something we can't solve in this issue, though.