#binary-search

Git Bisect: Stop Reading Diffs, Start Searching History

git bisect uses binary search to find the exact commit that introduced a regression, reducing up to 300 manual checks down to ~9. The workflow involves marking a known-good commit and a known-bad commit, then testing each midpoint git checks out and labeling it good or bad until the first bad commit is identified. The post walks through a concrete demo repo with a subtle argument-swap bug, shows the full command session, and compares bisect to git blame — explaining that blame answers spatial questions (who wrote this line?) while bisect answers temporal ones (which commit changed behavior?). Key limitations: bisect assumes monotonic bugs, and git blame fails for non-local causes like dependency bumps, merge commits, or refactors.