I'm not sure how you deduced that I'm actually a vi user, but it's interesting to see that vim has similar support but using separate linear undo and redo comma

I'm not sure how you deduced that I'm actually a vi user, but it's interesting to see that vim has similar support but using separate linear undo and redo commands g- and g+ . undo-persistance and undofile seem to be orthogonal to that though, I'm even less sure why you're bringing that up.