This skill should be used when a number looks meaningful and the reader needs to know whether it actually is — "is this an invariant", "find the invariant", "is the Collatz product conserved", "is that seed special", "does this pattern mean anything", "prove this is not a pattern", "hunt invariants", "is the ratio exactly 3^k", "why is this number suspicious". Measures the claim instead of asserting it, re-derives the measurement with independent code, and returns an honest negative with the residual that refutes it. Stdlib-only Python 3.10+, no network, no build step.
