Hmm, not sure I totally grok your question -- are you saying you want to describe a generic 400 response on a subset of routes, without manually adding that description to each route?

yep!

ie. if I apply my middleware to some routes, every route I apply it to will have that 400 response added to its swagger documentation

Ah, so I think conceptually what you want is for the 400 response to end up as data on each endpoint -- that's how it gets picked up by swagger. So this is the general problem of "how do I add data to a subset of endpoints". I think there are a few way to do this, and someone probably knows more than I do 🙂 One question first -- how are you selectively applying your middleware to those routes? Since data is applied recursively with meta-merge, you may be able to add the :response data at the same "level" of the route tree at which you're applying your middleware, and it will propagate down to the leaves.

hmmm... Currently I just apply it to each route, but I guess I could apply it to groups. Thanks

Honestly I wouldn't mind just putting that schema manually in each response map, I just wanted to make sure there wasn't a better way or obvious thing I missed before going ahead and doing it