On this forum I am watching the support/wordpress category. A few times, I’ve noticed topics in that category for which I haven’t received notifications. Here’s an example of one: WP + Discourse SSO Continuity Issue
Looking at the edit history of that topic, it has been recategorized from extras to wordpress. Possibly this is a regression from https://meta.discourse.org/t/category-watch-preferences-not-honored-on-recategorization/19441/7?u=simon_cossar
What do you think @sam? Relevant only to old prefs?
yeah we do not add a watch on recategorization, its a bit tricky cause we would have to “unwatch” strategically when you remove a category.
This could cause problems for a forum that is being used for customer support.
A non-technical solution is for the person who recategorizes the topic to add a reply to the topic that explains that they have moved it to the appropriate category. People watching the category will then get a notification. (I’ve only tested this on my local setup.)
Though this will only work for “watching”, not for “watching first post” (which is one of the big plusses of a discourse forum).
But it might work if you use the topic timer to republish into a new category. Or so I thought. Apparently it only works under certain conditions? Or does a scheduled publication never trigger notifications because the post has technically already been published?
Anyway to at least implement Watching First Post so those users get notified when the topic is new to them? It wouldn’t seem to be affected by the “unwatch” trickiness.
Most of our uses never add tags on topic creation and it’s a triage effort by staff which means all users that are watching tags will never get notified. 
This is an edge condition we should patch @tgxworld
@simon Are you stil able to reproduce this problem? I tried to reproduce this locally but I’m getting the correct notifications even after a topic is re-categorized.
Yes, I’ve just tested it on a hosted instance. I have three users, user_a, user_b, and user_c. I have set user_a to watch the ‘scratch’ category.
When user_b creates a topic in the ‘scratch’ category, user_a gets a notification about it when they login to the forum. This works as expected.
When user_b creates an uncategorized topic and then user_c recategorizes the topic to ‘scratch’, user_a does not get a notification when they login.
What I tested is that notifications are correctly delivered when a new post is created in the topic that has been re-categorized. Do you mean we should resend the notification when a topic gets re-categorized?
Yes. The case where this comes up for me is that I’m watching the Support > WordPress category. WordPress support topics are sometimes created in the wrong category and then moved by a staff member. When that happens, it would be good to get a notification.
A notification would probably be sent in this case if recategorizing a topic created a moderator post.
I think this is the same issue discussed here:
I wonder if this also applies to publishing topics created using the shared drafts feature…
@simon I fixed it in
https://github.com/discourse/discourse/commit/ee1eb1a5bd834ed49e7efe2ee58bb567556a8c7c
OK, tomorrow can you verify this is working as you expect here on meta @simon?
I just tested it on try.discourse.org and it worked as expected. When a topic is recategorized, users who are watching the recategorized category get a notification.