Thanks! 🙂 My use case was being able to add a middleware at runtime, from a function call at the runtime itself (rather than from CIDER/Calva). This way, libraries would be able to add middleware without needing any editor-specific setup. (Does it make sense to desire that?) (Anyway, for me this use case is on hold at the moment. In the thread above, I decided to rely on other methods to listen to user evaluations, for now -- just to avoid the setup details that caused some confusion. I'm hoping to explore the nREPL middeware option again in the future.)