Pairs where both forms have similar BM25 signals. If a Swift type carried sparser documentation than its NS counterpart, the ranker's content-length normalisation might flip the result. None of the 30 pairs tested exhibit this, but the test does not actively search for adversarial cases.
Cross-source deprecation. The HIG might document a deprecated pattern that Swift Evolution later modernised; this evaluation does not look at that axis. Class F (cross-source canonical) is the relevant Phase 1.x companion.
Symbol-level deprecation. Method-level deprecation (init(string:) deprecated in favour of init?(string:) on the same type) is not tested. Doc_symbols has the data; this corpus does not exercise it.
Platform-availability-axis "deprecation." A Swift API marked @available(*, deprecated) is structurally the same as a legacy NS class for an agent's purposes; this corpus tests one shape of the problem, not all shapes.