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: \[ Q_L^{\rm bundle}=2\pi, \qquad Q_{L\oplus R}^{\rm bundle}=4\pi>Q_{\rm address}^{\max}=2\pi. \] 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: \[ J_{\rm cc}^{\mu} =\bar\psi\gamma^\mu(1-\gamma^5)\psi, \qquad \mathcal L_{\rm cc} =-\frac{g}{2\sqrt2}\left(J_{\rm cc}^{\mu}W_\mu^+ + {\rm h.c.}\right). \] The mass-space interface is now kept logically separate from this chirality theorem. Its normalized gap vector is \[ (m_1,m_2,m_3) =m_\Delta\!\left( 0,\frac{1}{\sqrt{\rho^2-1}}, \frac{\rho}{\sqrt{\rho^2-1}} \right), \qquad \rho=2\pi\cos\!\left(\frac{\pi}{8}\right). \] A PMNS--Takagi theorem shows that mixing angles rotate the flavor basis but cannot tune these singular values. The frozen ratio line gives \(\Delta\chi^2=0.187708\) 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 \(\Delta\chi^2\simeq22.4\)--\(22.5\) 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.