Ask HN: A “GitHub Copilot” for Writing?

Does something like that exist? Basically, a tool that watches everything you type. And then offers auto completion based on your most used patterns. An auto generating, auto updating snippet library, so to speak.

Perhaps working like auto complete in Gmail, but based not on phrases that are common across a wide user base, but only on your own, personal writing. And, of course, running not in the cloud, but on your own computer, so it can be used for sensitive content.

Is there some thing that exists? If it doesn’t exist, would you want it to?