Chen–Čelikovský critical (a₂₂=0) — dx/dt = a·(y − x), dy/dt = d·x − x·z, dz/dt = x·y − b·z with b=3 fixed. Classic a=35 d=35. Dual a+d sliders. Distinct from chen.html (Chen–Ueta with +c·y term), chen-lee.html, lu.html (Lü–Chen), chua-multi, Sprott Jerk, San-Qi. Bulk centroid ≈ (0.00, 0.00, 34.06). RK4 critical bridge. Gold low-alpha trail, cap 650. RM = settled silhouette, no animate-on.