Equality Without a Monopole: The Charge Dead End and the Pair-Unity Derivation

The equality of the electron's and proton's charge magnitudes is the best-measured unexplained regularity in physics: neutrality experiments bound any difference below one part in 10^{21}, and no accepted theory derives the equality. The literature offers three explanations and all three are dead ends. Dirac's (1931) derives quantization from a magnetic monopole that has never been observed. Anomaly cancellation constrains the Standard Model's charge assignments but derives nothing — it is a consistency condition on numbers put in by hand. Minimal SU(5) explains the equality by multiplet embedding and predicts proton decay at rates Super-Kamiokande has excluded (tau(p→ e^+pi^0) > 2.4×10^{34} yr). This paper republishes, aimed at the dead end, the derivation given in The Pair Derives Charge (Paper 29): from the one-field postulate, production is pairwise, and a produced pair is one object with two faces — pair unity — so its charge is a single signed quantity appearing as +q on one face and -q on the other, and |q_+| = |q_-| is exact for every pair, by construction — the electron and the proton included, each a face of a pair under the one quantum. No monopole, no embedding, no auxiliary prediction a null result can kill. What the derivation does not do is printed in §5 at the same size: the proton–electron mass ratio is not derived — its scale law is priced in Paper 29, not produced — and the size of the charge quantum is a different address, held by the census, not by this paper.