Rucklidge — dx/dt = −κ·x + λ·y − y·z, dy/dt = x, dz/dt = −z + y². Classic chaotic (κ=2, λ=6.7). RK4, not Wang–Sun (a·x+c·y·z), not Lü (a(y−x), −xz+cy, xy−bz), not Chen, not Lorenz butterfly. Gold low-alpha trail, cap 650. RM = settled silhouette, no animate-on.