The Quantum Boundary of Black Hole Interiors: Signature Failure and the Termination of Mass Inflation

Classical general relativity predicts a singularity at the center of every black hole. We argue that it is never reached. We adopt the conjecture of Shaya (2026) that a metric element of non-Lorentzian signature is inadmissible: it cannot enter the Feynman sum over geometries, and so cannot belong t