Chromatophore Wave Kymograph

An octopus doesn't change color by mixing pigments — it changes how much of each pigment sac is stretched open, and the signal that drives that stretch travels across the skin as a spatial wave. This 2D companion unrolls a strip of chromatophore organs across space and stacks time downward into a kymograph, turning a traveling "passing cloud" display into a visible diagonal stripe and a synchronized flash into a flat band. A phase-portrait panel tracks one organ's coverage against its drive target, exposing the fast-contract / slow-relax hysteresis loop that gives real octopus skin its instant-on, fade-out signature.