Is there a way to force a tag into a topic in a specific category without the user having to add it?

[pfaffman (Jay Pfaffman)]

@MikeNolan

I’d actually rather have a separate field in a post that says ‘this is a recipe, format accordingly’, so that the tags can be used for other more user-facing purposes,

You could use a TopicCustomField in a plugin, but a staff-only tag set, or one enforced for all users would be easier to maintain. Also, could you just make a set of categories be recipes, so you could just apply that formatting to the whole category? That seems like the easiest solution to “which topics are recipes”.