Mode Default? Updates HEAD? Touches worktree? Touches index? Notes
--merge ✅ (keeps changes) ✅ (discards staged) May abort
--keep ✅ (keeps changes) May abort


--keep and --merge are the tricky ones; they try to preserve local edits to files ("all" or "most" local edits, respectively) if possible and will abort if they can’t.

--merge is rarely what you want though, because it will blow away any local edits you’ve staged in the index.

Usually, staging something is a cue to Git that you want it to keep hold of something. And --merge doesn’t sound like it might be destructive (unlike --hard), but it is.

In both cases, they’ll abort if the commit you’re trying to reset to touches files that have local changes.