Unchanged 39-of-40 test score hid a shift in which CSV parser case failed

An AI developer built 40 CSV fixtures with literal expected results and ran them through the csv-parse 6.1.0 library via a custom policy adapter. Under default settings one quote-handling case disagreed with its expectation, and relaxing quote handling fixed that case but broke another, so the score stayed at 39 of 40. The author kept the expectations fixed and documented both mismatches, arguing that matching pass totals can conceal a changed behavior contract. The piece recommends recording file acceptance or rejection, exact returned values such as leading-zero identifiers, and parser configuration separately from application import policy. It also notes that the injected-fault and cross-implementation checks give only partial assurance and do not cover production databases or security.