One rule, two senses — the nonlinear continuous axis

A single semantic-core-v1 manifest (Gray-Scott reaction-diffusion as ⟨State, Topology, Rule, Schedule⟩ data) advanced by the same modality-free stepper that runs Game of Life and heat diffusion. Diffusion's rate is linear; here the rate rule carries a nonlinear products term — the autocatalytic reaction U + 2V → 3V, i.e. −u·v² — that diffusion alone cannot express. From a small seed the inhibitor V grows into spots that divide and replicate: morphogenesis from a uniform field. The field you see and the chord you hear are the same V — neither modality rewrites it. The status line shows the tier, read from the manifest's axes.