The Frontier Current Is Fourier-Fixed and Reciprocally Positive
The moving-front profile
is both an exact derivative and a Fourier fixed point.
Poisson summation therefore converts its signed fine-mesh lattice sum into a reciprocal sum. On the positive theta chamber, every reciprocal sample lies beyond the profile's unique positive zero
so every reciprocal term is positive.
One rigid mechanism now explains both completed evenness and positivity: exact boundary current, Fourier self-duality, lattice discrepancy, reciprocal transport, and exclusion of the negative lobe.
This closes the source-positivity layer but not RH orientation of its oscillatory transform.
Research artifact: research/grothendieck/the-frontier-current-is-fourier-fixed-and-reciprocally-positive.md