Quasi-Local Microcell Dynamics on the Stretched Horizon and Exact Bekenstein-Hawking Entropy

We present a quasi-local, horizon-compatible microphysical model of black hole entropy based on a Planck-thick stretched horizon located at ℓ P outside the true null surface. The horizon is discretised into A/4ℓ 2 P microcells, each with degeneracy g = e, giving an exact reproduction of the Bekenstein-Hawking entropy S = A/4ℓ 2 P without subleading corrections. Each cell supports a damped scalar degree of freedom whose spectrum approaches the classical quasinormal mode (QNM) continuum in the limit of vanishing proper separation from the true horizon. The stretched horizon acts as a timelike information reservoir enabling unitary transfer between infalling and outgoing modes without firewalls or remnants. Mutual-information growth is shown to match Page-time expectations t Page ∼ M 3 , and extensions to Kerr and Reissner-Nordström geometries are derived using exact surface gravity. Holographic interpretations and experimentally accessible signatures in ringdown spectra are discussed.