Capacity Selection of Left-Handed Weak Interactions: A QTT Derivation of Neutrino Chirality, V−A Parity Violation, and the Mass-Space Interface

Can the handed weak current be selected without using neutrino masses to choose the answer? The capacity argument is local. A fundamental weak dyad consumes one completed modular budget at an address, while a parity-doubled pair would require two: \[ Q_Lᵇᵘⁿᵈˡᵉ=2π, QL⊕ Rᵇᵘⁿᵈˡᵉ=4π>Qaddressᵐᵃˣ=2π. \] Together with the visible/hidden address split and the dyadic equal-share closure, this selects one visible chiral branch and yields the standard charged current: \[ Jccμ =ψγ^μ(1-γ^5)ψ, Lcc =-g/2√2(JccμW_μ^+ + { h.c.}). \] The mass-space interface is now kept logically separate from this chirality theorem. Its normalized gap vector is \[ (m_1,m_2,m_3) =m_Δ\!( 0,{1}{√ρ^2-1}, {ρ}{√ρ^2-1} ), ρ=2πcos\!(π/8). \] A PMNS--Takagi theorem shows that mixing angles rotate the flavor basis but cannot tune these singular values. The frozen ratio line gives \(Δχ^2=0.187708\) and \(0.387921\) on the official NuFIT 6.1 joint profiles; the JUNO one-anchor prediction gives \(0.194936\) and \(0.684704\). The raw absolute source point under identity transport remains a separate \(Δχ^222.4\)--\(22.5\) scale-map test. The result therefore has two independently auditable parts: the finite-capacity selection of the left-handed weak branch, and the neutral mass-shape theorem with an open absolute source-to-laboratory transport boundary. Stable anchors: paper concept DOI; QTT Main Book v10.01; QTT Lexicon.