Hindmarsh–Rose — dx/dt=y−a·x³+b·x²−z+I, dy/dt=c−d·x²−y, dz/dt=r·(s·(x−xR)−z). Classic chaotic bursting a=1 b=3 c=1 d=5 r=0.006 s=4 xR=−1.6 I=3.2. Dual I+r sliders. Display embed (x,y,z). Distinct from duffing.html, van-der-pol.html, ueda.html, chua.html, lorenz.html. Bulk centroid ≈ (−0.8073, −3.5459, 3.1465). RK4 bursting neuron. Gold low-alpha trail, cap 650. RM = settled silhouette, no animate-on.