A single semantic-core-v1 manifest (heat diffusion as
⟨State, Topology, Rule, Schedule⟩ data) advanced by the same
modality-free stepper that runs Game of Life, the L-system and the
ecosystem. Here the state is a continuous value per cell and the
rule is a rate, not a match: du/dt = D·(mean of neighbours
− u), integrated one explicit-Euler step per tick under a
continuous-dt schedule. On a torus the mean-based stencil conserves
total heat exactly while every bump relaxes toward the average — so the hot
spot spreads and fades, mass preserved. The heat field you see and the
chord you hear are the same field — neither modality rewrites it. The status
line shows the program's expressiveness tier, read from its axes by the
shared classifier.