Party REPL is a multi-party Clojure REPL. The authors just gave a great talk on it last week at Clojure/Conj: https://www.youtube.com/watch?v=AJING0Vigpg Even if you're not into Clojure, it has a lot on the internals of a multi-party REPL and VS Code.

In addition to sharing code and a REPL, it also allows you to collaboratively edit HTML, CSS, web pages, etc. Really cool talk!