For contributions by new authors I usually don't make them do a respin for something minor, for instance if I think a more explanatory comment would be helpful

For contributions by new authors I usually don't make them do a respin for something minor, for instance if I think a more explanatory comment would be helpful -- I just fix those up when I commit. It saves the author doing multiple rounds dealing with a process they may be unfamiliar with, and it's usually less work on my end. For an established submitter the balance is more to ask them to respin, because they ought to be learning the project rules and process; even there I often fix up nits like typos in comment when committing rather than requesting a respin. I generally err on the side of retaining the authorship when I do this kind of thing (our project follows the kernel's de-facto standard of retaining the original git author but adding a note of extra changes made in square brackets after the author's signed-off-by and before mine as the committer, which is how we record who's responsible for what parts of a change like this). If you've literally completely written a fresh change to solve the same problem a different way then that should be your authorship with some kind of reported-by or other acknowledgement to the PR author, though.