Lengyel–Epstein — dx/dt=a−x−4xy/(1+x²), dy/dt=b(x−xy/(1+x²)), dz/dt=c(x−z). Classic a=12 b=0.3 c=0.15. Dual a+b sliders. Display embed (x,y,z). Distinct from brusselator.html, oregonator.html, selkov.html, schnakenberg.html, hinshelwood.html. Bulk centroid ≈ (2.3918, 8.3977, 2.3962). RK4 CDIMA fold. Gold low-alpha trail, cap 650. RM = settled silhouette, no animate-on.