I've been thinking about the malli-opts being defined in com.app instead of a file everything can import from. I'm guessing the idea was to have it only be accessible from ctx, but I have found it helpful to pool all my schemas in one namespace and create a registry there, ditching the :schema plugin key altogether. My reasoning 1. To me, there's not much point in letting every plugin define it's own schema since there's no "scoping" that comes with it. If you want your schemas in different files, you can do that and just have schema.clj import them all. 2. If you want to do your own validation, passing down the malli-opts to your functions can get more and more annoying. And if you want to use the malli schemas in metadata, you can't get it from function arguments. 3. Doing it this way lets you use generative testing a lot more easily across your Biff app, since you can access the registry directly. If you want to use function schemas from Malli, you can write a small function to easily select biff fields. Here is a function that can take a whole character object, but requires a few keys. It's validated at runtime and can be checked with generative testing.

(defn calculate-armor
  {:malli/schema [:=> [:cat (schema/get-fields :char
                                               [:char/armor :char/shield])]
                  :int]}
  [char]
  (let [armor-key (:char/armor char)
        shield-key (:char/shield char)]
    (+
     (armor-key {:modern 1
                 :bulky 1
                 :none 0})
     (shield-key {:on 1
                  :off 0}))))