Linear's write ups / talks on real-time sync are also very good, if a bit old now.

1. https://www.youtube.com/watch?v=WxK11RsLqp4&t=2169s

2. https://linear.app/now/scaling-the-linear-sync-engine

Also see this overview of related tech here:

3. https://gist.github.com/pesterhazy/3e039677f2e314cb77ffe3497...

And c.f. automerge from ink & switch:

4.https://automerge.org/blog/