Going Deeper into a Black Hole: The Horizon as a Quantum-Error-Correcting Record

A focused deep-dive companion to the gravity and black-hole paper (DOI 10.5281/zenodo.20671864) in the finite-QEC (quantum-error-correction) substrate series. It develops one thread: the black-hole horizon as a finite quantum-error-correcting record governed by a single object, the three-cube coboundary δ. Three results. (1) One δ controls the boundary strain record, the firewall isometry Vcell, and the single blind degree of freedom; the Hawking degeneracies and the area coefficient additionally require a register-validity/monogamy ingredient that is provably independent of δ. (2) The Bekenstein area law, in substrate units (node area a02/4, proton-primary G), is exactly equivalent to a microscopic records rate: each horizon node is assigned about 1038 nats while a cell holds at most 8 ln 2 ≈ 5.5, so the area entropy cannot be stored (standing storage fails by 37–45 orders of magnitude) and must instead flow, at rate H0MP2/(16ΛQCD3) = Cα02. (3) The coefficient is C = 55/8, with the value-level-versus-address-level direction-tag fork discharged by two independent arguments: the record channel is the syndrome itself, and AGL(3,2) covariance forbids an address-level orientation. Predictions: ΩΛ = 12π/55 = 0.6854 (α-free, +0.1σ, Planck branch of the Hubble tension); a universal, mass-independent horizon information bandwidth of ≈0.31 Eddington at the base service rate (≈43 Eddington at once-per-tick), with super-Eddington accretors as the falsification surface; and a discrete Hawking line spectrum with fixed integer-strain degeneracies and gap Fmin = 3. The absolute Planck-mass scale is not settled here: it rests on an un-derived α2, deferred to the gravity companion. Copyright (C) 2026 D. G. Elliman. Version 2.0 (2026-06-15). Added a ringdown-echo prediction: the firewall-over-rigid-core horizon reflects the graviton, so the remnant rings with post-merger echoes (general relativity has none). With the reflecting surface at the lattice cutoff a₀=1/ΛQCD, the spacing is Δt≈56 ms at 30 M⊙ (about half a generic Planck-scale echo) with R≈1 — a sharp LIGO/LISA test.