What I want: an undo graph, like vim's undo tree with merges. I want it visualized and browsable, maybe with real time sharing. It needs powerful git-like tools

What I want: an undo graph, like vim's undo tree with merges. I want it visualized and browsable, maybe with real time sharing. It needs powerful git-like tools for squash, rebase, etc so you can make neat changesets to publish for review.