∂expr/∂t < 0— Law of Erosion (Expression Capacity)

Structural depletion of expression capacity produced when action originates from derivative or fear-based identity. C_int accumulates. Output contracts. Glossary v3 correction: earlier notation ∂I*/∂t < 0 implied I* decay, which contradicts I* invariance. The correct formulation describes expression-capacity depletion, not I* decay. I* remains invariant; access to and expression capacity of I* degrades.