I don't know if this is what you're looking for, but that vaguely sounds like literate programming, and in particular tools like https://en.wikipedia.org/wiki/Web_(programming_system)#CWEB and https://en.wikipedia.org/wiki/Noweb

(Or maybe you're looking for something totally different; I'm not aware of anything that uses literate programming to feed hints back into an editor, although I'm sure someone has made emacs do it, probably using org mode;])