Currently users are not notified when a topic is moved to an existing category that the user tracks.
e.g. A topic in category XYZ is moved to Community Ops but the user doesn’t get a notification.
(User does get a notification if posts are moved to existing topic in a tracked category.)
@Kensie, you had some thoughts on this. You’d like the user to receive a notification? Did you want some other changes regarding moving topics?
Right, I was thinking that the quick solution might be to have a post in the topic created after the topic is moved, like how there is a post created when a thread is closed. That would trigger an update to the people watching the category that the thread exists if they never use the web interface.
Elsewhere you brought up whether users can watch individual threads, and they can. That’s a good point, it’s possible people who were watching the thread in the old category still want to watch it. We’d need to think about how to handle that case (being able to have a thread exist in multiple categories would be awesome here).
AFAIK Discourse now supports tags using an official plugin, I don’t know if that could solve that scenario.