Surgical Revert

Don't git reset --hard away three good commits to undo one bad one.

Single commit — git revert <sha> creates an inverse commit; history stays intact and shared-branch-safe.
One file from a commit — git checkout <good-sha> -- path/to/file.
Hunk-level — git checkout -p to revert specific changes, keep the rest.
A merge — git revert -m 1 <merge-sha> (pick the mainline parent). On a shared branch, always revert (forward), never rewrite history. Reproduce the breakage first so you revert the RIGHT thing, then verify the revert actually fixes it.

Invocation