Hinshelwood / Gray–Scott cubic autocatalator — dx/dt=(1−x)−Da·x·y², dy/dt=(η−y)+Da·x·y²−β·y, dz/dt=c(y−z). Classic Da=1000 β=10 η=0.05 c=0.5. Dual Da+β sliders. Display embed (x,y,z). Distinct from brusselator.html, oregonator.html, operon.html, selkov.html, schnakenberg.html. Bulk centroid ≈ (0.2523, 0.0724, 0.0725). RK4 chemical fold. Gold low-alpha trail, cap 650. RM = settled silhouette, no animate-on.