Horizon Microstructure and Boundary Constraints: Quantitative Requirements for Generative Horizon Dynamics

We present quantitative constraints on horizon microstructure required to support Horizon-Generator Cosmology and the Dual Horizon Radiation Correspondence. We introduce the microstructure correlation parameter Φ_micro and demonstrate it must satisfy 1.05 ≤ Φ_micro ≤ 2.0 for generative horizons. We derive explicit formulas for entropy corrections beyond the area law, establish time-scale constraints for microstate evolution, and predict measurable deviations in Hawking radiation statistics. String theory (fuzzball) and loop quantum gravity scenarios are compatible, while perfectly thermal horizons and remnant scenarios are excluded.