Adversarial Plan

Expected safe failures are distinct from numerical failures. Planned families cover invalid connectivity, inverted elements, singular systems, NaN/Inf, invalid material data, invalid time steps, solver failures and impossible contact states. Every expected failure must fail closed with a structured category and without state corruption.

Metamorphic checks cover numbering and element ordering invariance, rigid translation where appropriate, load scaling, sign-invariant modes and trial/commit/rollback reproducibility. Failures become anomaly records rather than tolerance changes.