Flavor and Leptogenesis Hardening of the QDL–SO10–1 Benchmark: Yukawa Textures, Neutrino Closure, Baryogenesis Viability, and Proton-Decay Feedback

The QDL–SO10–1 grand-unification sequence defines a closure-first SO(10)-compatible benchmark within the Quantized Dimensional Ledger (QDL) program. Papers #1–#3 established the initial benchmark trilogy: a fixed SO(10)-compatible benchmark, its low-energy phenomenology, and a stress-test / robustness audit. Paper #5 began the executable hardening sequence by revising the gauge-closure target to inverse alpha_U = 44.501718, corresponding to alpha_U = 0.022471. Paper #6 supplied a reduced block-level scalar-threshold derivation of the calibrated high-scale offsets, and Paper #7 converted proton decay from a scaling-level estimate into a benchmark-level operator exposure calculation with Wilson coefficients, hadronic inputs, channel-level lifetimes, and a reproducible v0.4 artifact. This paper supplies the v0.5 flavor and leptogenesis hardening layer. Its purpose is not to claim a final global SO(10) flavor scan or a unique microscopic flavor theory. Its purpose is to determine whether the QDL–SO10–1 benchmark is flavor-incoherent, or whether it can support a reduced SO(10)-compatible flavor ansatz that reproduces charged-fermion hierarchy, CKM mixing, type-I seesaw neutrino closure, PMNS mixing, neutrinoless-double-beta observables, baryogenesis viability, and proton-decay flavor feedback at benchmark level. The result uses a reduced H/F/G SO(10)-inspired texture at benchmark tolerance, not a complete global flavor scan. The v0.5 executable artifact produces charged hierarchy ratios m_u:m_c:m_t approximately 10^-5:3.5 x 10^-3:1, m_d:m_s:m_b approximately 1.1 x 10^-3:2.1 x 10^-2:1, and m_e:m_mu:m_tau approximately 2.9 x 10^-4:5.9 x 10^-2:1. The CKM benchmark magnitudes are |V_us| = 0.224998, |V_cb| = 0.041000, and |V_ub| = 0.003700. The light-neutrino spectrum is normal ordered, with m_1 = 0.0025 eV, m_2 = 0.0090 eV, m_3 = 0.0502 eV, Delta m_21^2 = 7.475 x 10^-5 eV^2, and Delta m_31^2 = 2.51379 x 10^-3 eV^2. The PMNS benchmark angles are sin^2 theta_12 = 0.304, sin^2 theta_23 = 0.573, and sin^2 theta_13 = 0.0222. The derived neutrino observables are sum m_nu = 0.0617 eV, m_beta_beta = 5.44 meV, and m_beta = 9.18 meV. A Davidson-Ibarra-style benchmark leptogenesis estimate gives epsilon_1 = 2.3844 x 10^-6 with central washout efficiency kappa_f = 0.010, yielding eta_B = 5.57 x 10^-10, with the efficiency scan spanning 1.67 x 10^-10 to 1.67 x 10^-9. This is classified as viable benchmark leptogenesis, not a full Boltzmann-equation computation. Finally, the v0.5 flavor factors are fed back into the proton-decay lifetimes of Paper #7. The updated lifetimes remain above present bounds: tau(p to e+ pi0) = 2.396423 x 10^36 yr, tau(p to mu+ pi0) = 4.088415 x 10^37 yr, tau(p to anti-nu K+) = 6.459280 x 10^37 yr, tau(p to anti-nu pi+) = 7.170619 x 10^36 yr, and tau(p to e+ K0) = 5.885232 x 10^38 yr. Relative to Paper #7, the v0.5 feedback shortens the p to anti-nu K+ lifetime by a factor of approximately 2.25 while keeping it roughly 1.1 x 10^4 times above the Super-Kamiokande comparison limit used in the paper. Thus QDL–SO10–1 survives v0.5 flavor and leptogenesis hardening at benchmark level. The result closes the last major open technical layer of the hardening sequence and makes the benchmark synthesis-ready for Paper #9. The v0.5 standard is not arbitrary flavor fitting; it is flavor closure under QDL admissibility with leptogenesis and proton-decay feedback.