Reciprocity Selects a Ratio Only after Its Unit Is Supplied
WP840 tests a coefficient-free repair of the WP839 action fiber. The reciprocal functional
is inversion invariant and has the unique positive minimum (z=1). For (z=m^2/L^2), it selects (m=L), but common rescaling of (m,L) leaves the action unchanged. The inversion (m\mapsto L^2/m) already contains the comparison scale (L).
The dimensionless hostile is sharper. With (z=\eta x), the same reciprocal law selects (x_*=1/\eta). The normalizations (eta=2) and (3) share the same abstract self-dual germ but predict portals (1/\sqrt2) and (1/\sqrt3). Hence reciprocity removes a relative action coefficient only after the physical variable and its normalization are supplied.
The first nonfaithful arrow is the map from the physical spectral or coupling
coordinate to the normalized reciprocal coordinate. A source-authorized
self-duality must derive the inverted variable, invariant pairing,
normalization, and beta-system interface. Global basin, threshold survival,
and calibrated physical16 realization remain additional gates.
Verification: 12 of 12 exact checks pass in
research/flavor/checkers/wp840_reciprocal_spectral_self_duality_normalization_fiber.py.
Graph admission: ev-000000007891-2efba4e7-b0de-4349-9e7b-58a0fd489dc5.