bug-autopsylisted

The expensive failure mode isn't the bug — it's an AI *guessing* at the cause and "fixing" code it never proved guilty. Guess-patches breed regressions, and three guess-patches deep, nobody knows what the system even does anymore. For the full catalog of ways to build and tighten a repro loop, see [building-repro-loops.md](building-repro-loops.md). ## The discipline 1. **Build a red light first.** Before any theory, construct one command that reliably shows the bug — a failing test, a script, a curl. If you can't trigger it on demand, you don't understand it yet; keep working on the trigger, not the theory. For flaky bugs, raise the reproduction rate until it's debuggable — loop it 100×, pin the randomness, narrow the timing. 2. **Shrink it.** Cut inputs and steps one at a time until everything that remains is load-bearing. A minimal repro shrinks the suspect list for free. 3. **List 3 candidate causes before testing any.** One-hypothesis debugging anchors on the first plausible story. Each candidate must make a testable prediction: "if X is the cause, changing Y makes it disappear." 4. **Test one variable at a time.** A probe that changes two things proves nothing. 5. **Fix the proven cause only.** No drive-by cleanups in the same change. 6. **Re-run the red light** — now green — plus the full test suite. Turn the repro into a permanent regression test. ## Hard rules - No repro, no patch. "It's probably X" is not a diagnosis. - Production systems get read-only inspectio