I thought about this once and came to the conclusion that the problem doesn't exist: Anger is the only thing you can accomplish by typing letters into the sentence I'm writing. If the goal is not anger but to write text only one person can write a sentence at a time.
The solution then becomes really simple: You insert your cursor where you want to edit. You wait for the text and/or background of that paragraph to change color. Light green would do nicely.
Other users will see that paragraph turn red.
The paragraph is now under your control. If someone else desires to edit a sentence in YOUR paragraph that sentence changes color again and the side bar displays a dialog allowing you (the owner) to 1) hand over the paragraph to the new author, 2) hand over only that sentence or 3) ignore the request.
That falls apart as soon as the author with the locked paragraph leaves the document open while they’re doing something else, preventing others from editing.
I really don't get it. You want to add thousands of lines of code and complex data structures with tons of edge cases so that I can interrupt you while you write??? It's just not desired functionality. Poor network connectivity is not an excuse to break your workflow.
You simply do not assign 2 people to a task that can only be done by a single person.
It is like a system where 2 people can poor coffee into the same cup at the same time. We deal with the cup overflowing with some drainage (marvel at our creation of course!) but then 12 people put sugar in the cup. Solution: we overflow the cup further to dilute it! We solve the mobility issue by spilling a bit more coffee out of the cup and whip the bottom with just the right type of towel or napkin. The only problem that remains is both drinking from it at the same time.
The solution then becomes really simple: You insert your cursor where you want to edit. You wait for the text and/or background of that paragraph to change color. Light green would do nicely.
Other users will see that paragraph turn red.
The paragraph is now under your control. If someone else desires to edit a sentence in YOUR paragraph that sentence changes color again and the side bar displays a dialog allowing you (the owner) to 1) hand over the paragraph to the new author, 2) hand over only that sentence or 3) ignore the request.
Dumb software wins!