The Radical-FDRS One-Dimensional Flattening Methodology and Its First Experimental Pass: Radical Closure, X-Diagonal Coupling, the Boolean Cube and Squareclass Defect Dynamics

Recasts the perfect cuboid as a one-dimensional radical-closure / Boolean-cube 'FDRS tape' problem whose goal state is all six squareclasses κ_i = 1, with the seed (448, 495, 840; 1073) as the single-defect state K = (1, 1, 1, 233·1913, 1, 1); in the first experimental pass exact toy examples show squareclass defects can migrate between channels ((1,1,1,5,5,2) → (1,3,5,1,6,2)), a dual-squareclass compatibility table on {1, 2, 3, 5, 6} is derived, an isolated face-defect kernel must be a sum of two rational squares (excluding 3 and 6), and a bounded scan (edges ≤ 30000) finds no one-defect cuboid with κ = 2 or 5 ('bounded negative evidence').