undo-tree for emacs can do this. I think spacemacs enables this by default https://stackoverflow.com/questions/2985050/is-there-any-way-to-have-emacs-save-your

undo-tree for emacs can do this. I think spacemacs enables this by default https://stackoverflow.com/questions/2985050/is-there-any-way-to-have-emacs-save-your-undo-history-between-sessions https://stackoverflow.com/questions/2985050/is-there-any-way... It really saves the whole tree, not just the path that was active at the time of exit.