The Full CMB Power Spectrum in Black Hole Cosmology: A CLASS Boltzmann Code Analysis (Interior Observer Paper 6)

Paper 6 in the Interior Observer (IO) cosmological framework, which proposes the observable universe exists inside a Schwarzschild black hole. The full CMB TT angular power spectrum is computed using the CLASS Boltzmann code (v3.3.4) with IO framework parameters (H₀ = 58.2 km/s/Mpc, Ω_m = 0.197, Ω_k = −0.130, T_CMB = 2.6635 K) and ΛCDM primordial parameters (A_s, n_s, τ_reio). ΛCDM validation passes: ℓ₁ = 221, matching Planck. The IO spectrum is a clean geometric rescaling of ΛCDM — all five acoustic peaks are shifted uniformly ~17% to larger angular scales (ℓ₁ = 180, ℓ₂ = 445, ℓ₃ = 690, ℓ₄ = 950, ℓ₅ = 1204). Peak spacing, odd-even asymmetry, damping tail, and baryon loading physics are preserved. The first peak is 33% taller due to enhanced early integrated Sachs-Wolfe effect from earlier matter-radiation equality (z_eq = 1748 vs 3403). The IO framework does not break plasma physics — it changes the geometric ruler. A two-dimensional parameter sensitivity scan over Ω_m ∈ [0.15, 0.315] and Ω_k ∈ [−0.20, −0.02], with H₀ derived self-consistently from the IO geometric constraint, reveals that ℓ₁ is structurally locked to [171, 198] across the entire viable parameter space. No combination of IO parameters can reproduce ℓ₁ = 220 without requiring H₀ < 35 km/s/Mpc or violating BBN bounds. The 18% peak tension is a rigid, parameter-independent prediction. Root cause: the sound horizon at baryon drag is 23% larger (180.4 vs 147.2 Mpc), driven by lower physical matter density ω_m = 0.067 vs ΛCDM's 0.142. The angular diameter distance is nearly identical due to closed geometry compression (sin(χ)/χ = 0.70). Resolution requires a mechanism to increase H(z) at z > 1100 without altering the late-time BAO fit — notably the same requirement identified by the broader cosmology community for the Hubble tension. All CLASS outputs independently verified by analytical computation (Wolfram/ChatGPT 5.3). Peak positions are zero-parameter IO predictions; absolute peak heights are not claimed (borrowed A_s). Relative peak ratios (including the eISW first-peak enhancement) are emergent physical properties of the IO matter-radiation equality epoch. Multi-AI research: Claude Code (Anthropic) for CLASS computation and parameter scan; Wolfram/ChatGPT 5.3 (OpenAI + Wolfram) for analytical verification; Gemini 2.5 Pro (Google DeepMind) for adversarial review; Claude (Anthropic) for orchestration. Companion to Paper 1 (DOI: 10.5281/zenodo.18854813), Paper 2 (DOI: 10.5281/zenodo.18868612), Paper 3 (DOI: 10.5281/zenodo.18876346), Paper 4 (DOI: 10.5281/zenodo.18883069), and Paper 5 (DOI: 10.5281/zenodo.18889865).