The full/full branch has zero nonconserved external mode #
This is the frequency-conservation part of paper Section 4.2 before the
Step-4 endpoint estimate. A full/full contraction has no cross-copy
covariance slot. Hence every nonzero Fourier configuration forces
alpha + beta = 0; at a nonzero external shift the complete refined fibre
vanishes.
The configuration expansion and its conservation theorem already exist. This file only transports them through the exact full-pairing and refined finite-fibre reindexings. No estimate or triangle inequality is used.
One full/full contraction term vanishes when the external shift is nonzero. This is the integrated Fourier-conservation statement, obtained by reusing the existing exact configuration expansion.
A residual-refined fibre represented by two full halves vanishes at a nonzero external shift. Fullness propagates through the fibre by the already proved endpoint-signature rigidity theorem.