Diffusionless Lorenz — dx/dt = a·(y − x), dy/dt = −x·z, dz/dt = x·y − R. Classic a=1 R=1 (van der Schrier–Fournier). Dual a+R sliders. Distinct from lorenz.html, lu.html, chen.html, pham.html, jafari.html, malasoma.html. Bulk centroid ≈ (0.0060, 0.0069, -0.0004). RK4 diffusionless fold. Gold low-alpha trail, cap 650. RM = settled silhouette, no animate-on.