Liu system — classic 3D chaos (Liu et al. 2004) — dx/dt = a·(y − x), dy/dt = b·x − x·z, dz/dt = −c·z + x·y. Classic chaotic a=10 b=40 c=2.5 (c fixed). Dual a+b sliders. Two-wing fold distinct from Lü (lu.html), Chen–Ueta (chen.html), Chen–Lee, Rikitake, Moore–Spiegel, Rayleigh–Bénard, Hadley, Dequan–Li, Coullet, Burke–Shaw, Sprott–Linz A–S, Finance, Bouali, Genesio–Tesi, Arnéodo, Newton–Leipnik, Rucklidge, Wang–Sun, four-wing, Dadras, Halvorsen, Chua, Aizawa, Thomas, Rössler. Bulk centroid ≈ (0.15, 0.18, 37.41) from warm 20k + 80k RK4 @ dt=0.001. RK4, not lu.html, not chen.html, not chen-lee.html, not rikitake.html. Gold low-alpha trail, cap 650. RM = settled silhouette, no animate-on.