git bisect is the debugging tool I forget I own
A binary search through history that finds the exact commit that broke things.
When something worked last week and doesn’t today, I used to read diffs and guess. Bisect turns it into a binary search: mark a known-good commit, a known-bad commit, and git walks you to the culprit in log-n steps.
git bisect start
git bisect bad
git bisect good v1.4.0
# test, then mark each step:
git bisect good # or: git bisect badOn a repo with a thousand commits between good and bad, that’s about ten tests instead of a thousand. The first time it pinpointed a one-line change buried in a merge, I was sold for life.