[iudqnolq]

> That sounds like interactive staging (`git add -p` or `git add -i`). You can do the same in magit, in the status window by selecting the diff lines you want to stage. I use evil-mode and use visual mode for that selection. Am I missing something about your requirement?

At least in magit, you get the error "new file ... depends on old contents" if you try to stage a hunk of a newly created file.

(i.e. echo "foo\nbar" > file, then stage only "bar")