This work presents the complete, three-stage resolution of the cosmological constant problem — the 10^122 discrepancy between predicted and observed vacuum energy density that has resisted solution for nearly four decades. The derivation proceeds from three independent, non-adjustable roots: 1. κ_crit = 10^-78 — The causal coherence limit derived from entropic equilibrium (Ṡ_net = 0) at the Planck scale. 2. φ/2 = 0.809017 — Geometric contribution from the 3D projection of the 8-phase causal tesseract onto a regular pentagon (diagonal/side = φ). 3. 3/4 = 0.750000 — Thermodynamic offset from the half-phase squared (1 − (1/2)² = 3/4), representing the fraction of Planck energy that survives the causal membrane's maximum tension point. These combine to give the vacuum exponent: α = φ/2 + 3/4 = 1.559017 The vacuum energy density is then: V₀ = E_Planck × κ_crit^α = 2.50 × 10^-122 M_Pl⁴ This matches the observed dark energy density (ρ_Λ ≈ 6.90 × 10^-27 J/m³) with Δ = 0.0000 orders of magnitude. No free parameters. No fine-tuning. No dynamical evolution required. The repository includes: - Complete LaTeX manuscript with full derivation - Python script with numerical verification and visualizations - All figures generated during the analysis