Coincidentally, I'm in the middle [1] of building something for https://CoCalc.com https://CoCalc.com that is exactly what you're describing. For collaborative

Coincidentally, I'm in the middle [1] of building something for https://CoCalc.com https://CoCalc.com that is exactly what you're describing. For collaborative document editing (e.g., google drive and overleaf) it's a common feature, but for code editors it isn't. CoCalc is both. Anyway, nothing to see yet, but you might want to check with us in a month. After thinking about this problem a lot recently, I think it’s critical to store the comment locations with all versions of the file, so you don’t lose comment locations, or at least maximize the information you have available to locate comments when they get lost. [1] https://github.com/sagemathinc/cocalc/pull/8071 https://github.com/sagemathinc/cocalc/pull/8071