Green CI proves nothing failed. Here's a deterministic check that proves nothing regressed.

Your CI is green. The PR merges. Prod breaks anyway. A passing test suite proves exactly one thing: no test that exists, failed. It does not prove that nothing regressed. The two are different, and the gap is where real incidents live — especially now that AI agents open PRs faster than anyone can review them, and "that test is just flaky" has become a reflex. When something that worked before breaks after a green merge, there is usually no machine-checkable record of what regressed or why the...