A sharp finite-profile decoherence floor in two-kernel classical-quantum gravity

This preprint derives an attained, coupling-parameter-free lower bound on thedecoherence rate generated by a static Markovian two-kernelclassical–quantum gravity model. For any fixed mass-density difference withfinite positive profile functionals, complete positivity implies `Gamma >= (4*pi*G_N/hbar)*sqrt(Q_loc*Q_mu)`. At vanishing infrared regulator, a homogeneous sphere admits a closedpiecewise separation law. A sharp boundary gives a small-separation exponent3/2, whereas smooth profiles give a quadratic law. At finite regulator, theinverse bi-Yukawa kernel gives the exact point-profile crossover`Q_mu=m^2[1-exp(-mu*d)]/(4*pi*mu)`, so massless square-root growth is replacedby saturation at fixed positive regulator. An independently inferredexcess-decoherence upper bound below the floor would exclude the declaredtwo-kernel class for that profile. A secondary two-profile condition testswhether several profiles can share one global coupling pair. The result is model-specific. It is not a theorem for arbitrary classicalgravity, additional kernels, running couplings or uncalibrated visibilityloss. The record contains the manuscript, LaTeX source, a dependency-freeverification program, expected output and immutable hashes.