- test_fixture_sweep: extract+validate every fixture PDF on every run; known extractor/validator gaps are catalogued explicitly and the sweep fails on any deviation from that catalogue - tests/fixtures/real/: anonymized XML from real production invoices that revealed bugs (verified to contain no real-world data); first entry locks in the FC-tax-number/basis-quantity/spaced-VAT-ID regressions - CI workflow: uv sync --frozen from lockfile + pytest + docker build