4 Spatial interaction and the rank-one boundary

The spatial manuscript (05_spatial_pricing) studies a row-stochastic interaction operator inside a finite-dimensional SAR model. Its formal contribution is deliberately narrower than an equilibrium asset-pricing model: it verifies compatibility of the constructed operator with the SAR norm gate, links a quantitative contraction certificate to Perron convergence, and separates exact finite-\(\rho \) algebra from the strong-interaction boundary.