repro-firstlisted

# repro-first A real bug gets a failing test that reproduces it *before* the fix lands. The test is the regression guard for next time. **No fix without a repro.** ## Steps 1. **Reproduce locally first.** Pull evidence for THIS specific failure — the actual error, log, stack trace, or input. Don't theorize a root cause from "usually it's X"; get the real signal for this run. 2. **Write the failing test** at the right layer — unit test, integration case, fixture, or a matrix row — that fails *because of* the bug. Run it; confirm it fails for the expected reason (red for the right cause, not a typo). 3. **Fix** the code. 4. **Confirm green + no collateral.** The new test passes, and the surrounding suite still passes — run the gate that covers the change, not the whole world. 5. **Keep the test.** It ships with the fix in the same change. Don't delete it, don't mark it skip — it's the guard for the next regression. ## Non-negotiables this enforces - **Real bug → repro before fix** (rule #34): the failing test lands with the fix. - **Never invent root causes** (rule #5): evidence for this run before a theory. - **Reproduce locally before pushing** (rule #11).