Boundary Parity: The Geometric Origin of Fermions and Bosons external substrate (co-rotating) counter-rotating boundary shell core ×(−1) 1 counter-rotating layer internal chirality ≠ background odd boundary parity = fermion Fermion (electron) external substrate (co-rotating) ×(−1) outer boundary (counter-rotating) ×(−1) core 1 core 2 inner seam (counter-rotating) 2 counter-rotating layers (−1) × (−1) = +1 internal chirality = background even boundary parity = boson Boson (modon / photon) Each counter-rotating layer inverts chirality. Odd inversions → polarized (fermion). Even inversions → transparent (boson).