Improve Undo, persist history buffer across tab closure

[1hko]

VSCode makes me fearless closing files amongst my crowded tabs, because I know I will never lose work or that work's context, including that work's recent changes. In Zed, when I close a file, all of that history is gone :(

1. Make a change in a file
2. Save it
3. Close the file
4. Reopen the file using command-shift-T
5. Press command-Z to undo.. nothing to undo 👎

It I close an entire project window or quit Zed, I think it's safe to clear file history. That's how VSCode handles it anyway. In any other case, maintaining this valuable history has become essential to my workflow, freely opening and closing files without losing any work.

[towhans]

I store undo history per file in vim. Simple and powerful. I miss that feature in Zed.

" Keep undo history across sessions by storing it in a file
if has('persistent_undo')
    let myUndoDir = expand(vimDir . '/undodir')
    " Create dirs
    call system('mkdir ' . vimDir)
    call system('mkdir ' . myUndoDir)
    let &undodir = myUndoDir
    set undofile
endif