Same student. Two tutors. One can teach a wrong answer — the other structurally cannot.

Generic AI tutors run an unconstrained language model: on a subtly wrong premise they confidently affirm the error. The Precision Mastery Engine binds every diagnosis to validated knowledge and checks the chemistry against a deterministic oracle — a wrong claim is blocked before any student sees it, and only an author-verified fix is served. Run the same sentence through both.