what does :rpc/pre mean? I found it here for example:

(defrpc update-user [user-data]
  {:rpc/pre [(update-record! user-data)]}
  (fetch-record (:db/id user-data)))

googled around and couldn’t find anything.

check out the castra source (https://github.com/hoplon/castra/blob/master/img/arch-full.png, core.clj and middleware.clj)

I have a question myself - I understand I can't nest if-tpl directly inside loop-tpl, but is there a reason the following should not work? '(tpl-loop ... (div ... (if-tpl ...'