IV.D376 — Higgs Self-Coupling from τ-Chain

λ_H = m_H(τ)²/(2·v_EW²) = 0.12928 at +16 ppm from SM 0.12928. Coherence functional curvature at ω-crossing equilibrium. Not a free parameter but derived from m_H(τ) and v_EW. Inherits precision from IV.T166 (m_H at +8 ppm).