bisect-regression

name	bisect-regression
description	Find the exact commit that introduced a bug. Use when something worked before and broke, and you don't know which change did it.

Bisect the Regression

1. Find a known-good commit and a known-bad one. Confirm both by actually checking out and testing.
2. git bisect start; git bisect bad <bad>; git bisect good <good>.
3. At each step, run the SMALLEST test that distinguishes good from bad. Mark git bisect good/bad.
4. When git names the first bad commit, read its diff. The bug is in those lines — don't guess elsewhere.
5. git bisect reset. Report: the commit, the line, the one-sentence cause. Automate it: git bisect run ./repro.sh if you have a script that exits non-zero on the bug.