

Updated OP with what I came up with. I wasn’t able to make use of $GIT_REFLOG_ACTION – for some reason it was blank in every case, but reading the first line of the existing commit message, if it exists, does the trick.
I do foresee a potential problem if you’re doing like an interactive rebase for example, and you go to edit a commit message that starts like the default "Revert " style–that could be surprising… Maybe some other cases I haven’t thought of too, but yeah, works for me. Thanks for pointing me in the right direction!

Neat, but I don’t like how it highlight the entire like if I change just one character on that line.
Maybe there’s a setting I’m missing, but I really like
diff-so-fancyfor legibility of changed lines.For example if I’ve got like these changes:
--- a 2026-06-01 14:36:20.699016620 -0400 +++ b 2026-06-01 14:36:21.842027381 -0400 @@ -1,11 +1,10 @@ foo bar -baz +bazz foo -bar baz -foo +bar bar bazdifftshows me:but
diff-so-fancyshows me:Imho it’s easier to read the pertinent info in the latter, where you’ve got that attractive word diffing on changed lines.
I do like the conditional side-by-side and unified diffing, though. That’s huge.