I implemented editable posts on ssb, it's possible.

I posted a new message type 'edit', edit: 'posthash', content: 'new content' and then I collected all of the message edits, order by timestamp (ssb-query did this for me), and render a message that shows the differences between the edits. I only rendered a diff at the time, but I wanted an arrow where you can quickly pass over the edit timeline.

I'm pretty sure the code is on `git-ssb` somewhere.