@kartik_prabhu amazing work overall! This is one of my favourite parts though — the fact that fragmention comments fall back gracefully if they’re not supported on either side, and yet all the data required to present them is preserved, so future updates can retro-actively put old marginalia in the right place!
I wonder how tricky it would be to implement this on the comment publisher side too — detecting fragmention URLs and tailoring the reply context content…