Entanglement-Density Gravity II — The Perturbed Horizon: the modular response of entanglement dark energy

Companion to "Entanglement-Density Gravity: The vacuum does not gravitate." If dark energy is the entanglement of the cosmological horizon, it must respond when cosmic structure perturbs the expansion. We compute that linear response and find the theory has no freedom in the answer: a horizon charge responding locally to structure would suppress the present clustering amplitude σ8 by a factor of eleven and is excluded outright, while the modular structure of the charge supplies a derived smoothing window that decouples sub-horizon scales automatically and leaves a parameter-free, fixed-sign suppression of clustering confined to near-horizon scales. The perturbations fall in the momentum-exchange (Type III) class of interacting dark energy: background uncoupled, perturbations coupled. For Paper I, this pins the origin of the sub-horizon signal and replaces its clustering assumption with a derived support condition.