This browser addon tells me where I started writing something and what it was. Or what I just read and didn't have a chance to reply to.
I can pin down and add a quick comment (AI perhaps can be helpful here, if and when it gets a bit better).
Once I finish it marks that chat with a V.
If
I scrolled back to some old conversation it knows how many pages I scrolled up (on the phone) and could show me which post I was looking at when I got the phone call at the same minute that my reminder rang and I smelled the food which I forgot on the fire.
Or if I simply answered somebody, and want to return to viewing the stupid videos on the choir's chat.