Earlier quoted context omitted.
"multiplayer notepad" goes back 15 years at least - https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu... it was used back with a popular website which opened a text document and anyone viewing could type, but I can't remember the name. That became a thing in Google Docs, Microsoft Office, Floobits, and lots of self-hosted and cloned sites.
You may be thinking of Hackpad from 2014, which later was bought by Dropbox and morphed into Dropbox Paper. I guess I was thinking that a multiuser IDE is substantially different than a multiuser text editor. I did notice that Zed is by the same team that brought us tree-sitter, which is a wonderful innovation that many text editors are now using to good effect. I was wondering if were powerful enough for one person…
https://en.wikipedia.org/wiki/Etherpad
https://en.wikipedia.org/wiki/Collaborative_real-time_editor...