Really nice article. I think the undo/redo for rich text is a tad bit more complicated than undo/redo for objects with properties.
For starters, in your demo when user A has selected some word and user B writes a letter in it, user A lost the selection. And this isn't even undo/redo yet, just normal collaborative thing.
That "some extra plumbing" you mention is quite big. Please don't get me wrong here – I would love to see you pull it off – Liveblocks.io seems like a good platform from what I read & heard, but you underestimate how hard that problem might be.
Notion’s selection and undo/redo with multiplayer are pretty potato. Notion stores selection as grapheme indexes in a text property, so while it won’t lose selection if someone adds/removed characters from a text, your selection won’t make as much sense as one in Google Docs. Likewise with undo/redo or regular typing into the same field - it’s all last-write-wins updates.
On the other hand, Notion’s editor does a much better job with CJK input, Android, etc compared to Slate. Slate has a beautiful API design but its implementation suffers outside of ideal conditions.
Awesome to hear from the Notion team who really gets this deeply.
Slate definitely has its own limitations, especially when used on non desktop devices. Seems like ProseMirror would be a good open source alternative to Slate, what do you think?
ProseMirror did the best the last time I tested these libraries. TipTap (a competitor of yours?) provides an API layer on top, which I haven’t spent much time investigating. For my purpose I don’t want intermediary abstractions - but might be useful for your context depending on how much you want to specialize in rich text.