Well ten years ago there was nothing. Nowadays there's a LSP server for Clojure and it'll tell you where, say, a function is used. It's not IntelliJ for refac

Well ten years ago there was nothing. Nowadays there's a LSP server for Clojure and it'll tell you where, say, a function is used. It's not IntelliJ for refactoring a Java codebase but it's not either "nothing telling you if the pieces still fit together". As it's LSP, it works in any text editor supporting the LSP protocol, so it's here to stay. Besides that as others have mentioned: Clojure spec, various kind of automated testing, including, if that's your thing, generative-testing/property-based testing generated based on your specs (it's not always trivial but can really help at times).