Identical Entrance Doublets Carry an Undeclared Kinetic Gram
Canonical wavefunction normalization is a presentation quotient for isolated connector fields when every coupling is transformed with the field. The two entrance doublets are exceptional because they have identical gauge representations. Gauge symmetry permits a general positive two-by-two Hermitian kinetic Gram.
The canonical Gram gives orthogonal up/down Yukawa axes. The equally legal
positive Gram [[2,1],[1,2]] has determinant three and canonical-axis overlap
squared one quarter. Canonicalizing it while retaining the old axis-aligned
Yukawa tensors silently deletes a source coordinate.
The smallest repair is a source symmetry distinguishing the two doublets, or an enlarged model containing the full kinetic and Yukawa tensor system. This is a model-export obstruction, not a flavor selector or detector instrument.
Evidence: research/flavor/flavor-entrance-kinetic-gram-obstruction.md and
research/flavor/results/wp628_entrance_kinetic_gram_obstruction.json.