A sharp three-point kernel bound and improved proportions of zeta zeros

We prove that the auxiliary ratio in Wang's three-point kernel argument has sharp maximum sqrt(2), attained exactly at (0,1) and (1,0). Substitution into the source-pinned framework of arXiv:2609.24167v1 gives a lower proportion 0.6725007995946757558... of nontrivial zeta zeros that are simple and on the critical line, with a distinct-zero companion 0.8362503997973378779.... Directed rational intervals and an independent 120-decimal interval replay certify the numerical comparisons. The global transfer depends on a recent unreviewed preprint. The result is asymptotic and does not prove the Riemann hypothesis.