soxa

This PR can be merged without the previous one as QA is being done here, and new changes and fixes are being pushed here. If it's better to do the...

> to build something we can be confident in Agree, the new architecture allows us to do pretty much whatever we want to do with Markdown, and that's a really...

Oh okay! It makes sense to allow media/embeds only if they're in their own paragraph. I explicitly did the opposite!

Yeah that is something that we have in prod too. Edit mode unmounts and re-mounts the `Text` component, causing media checks to run each time. We can likely simply hide...

> triple-click behavior in the markdown editor. actual: selects all text for some reason. expected: selects the paragraph. ```javascript editor.registerCommand(lexical.KEY_ENTER_COMMAND, event => editor.dispatchCommand(lexical.INSERT_LINE_BREAK_COMMAND, false)); ``` I was weirded out too,...

> more of question: curious about the reason for keeping LegacyText We don't actually need it! Especially now that lexical states are computed on-request. It was really useful for live...

Adding to the nits: - nested checklists turn into abstract art (lexical vs prod) - too much spacing --- Addressing nits: - something affecting heights of the media containers didn't...

> only curious: useCallbackRef what's it being used for? The useCallbackRef is needed for Lexical because we dynamically load the Reader, which means that its ref isn't available immediately on...

I'm missing some READMEs (components and server), but other than that, this PR feels ready to be reviewed. I’ll finish writing them ASAP.

Ah, forgot to do something about it! This will probably involve creating our own `PlainTextExtension`.