How will your UI display comments like a chatroom when they are deeply nested?

Simple: there is no nesting :) it’s a flat chain ordered by date. It’s a design choice by zulip, not necessarily better in all cases, but is driven by different design decisions: discussions are expected to be about converging to something, so everyone is expected to read everything in a thread. If the subject diverges, it is expected to move to another thread. So instead of branches there is a set of topics, and you can mute some if you want to

So we have the basic architecture already there and it wouldn’t be much work to provide what you need.

Indeed there is the architecture, it should be feasible. I might join and even have a go at it at some point (so I can add the before/after haha)

Thanks for the pointers !