Scope boundaries

A derivative primitive does not establish convergence of every PDE solver. A soft relaxation is not a universal exact discrete solver. A model-relative certificate is not a certificate about the physical world without additional assumptions.

Full mixed jets have combinatorial output size. Deep direct Laplacian costs still depend on input dimension. Deep repeated derivatives can switch from exact support enumeration to a reported estimator. Closed-form floating-point expressions can still experience cancellation.

Numerical agreement is workload- and dtype-specific. See the full guarantees and the evidence.