Debug from a failing reproduction

Claude turns a bug report into a test that fails the way the customer saw it. You check the test, then Claude fixes the code until that same, locked test passes. It can't edit the test to get there.

Our run, 2026-09-26. From the bug report, Claude wrote a test that failed the way the customer saw it (3 May, not 5 April), changing no code. After /fix the same test passes, unchanged, and 11 of 11 tests pass.