We derive the complete structure of Inverted Hypersphere Cosmology (IHC) from a single logical necessity: nothingness is self-contradictory. The instability of pure nothingness necessitates the existence of a quantum field of potential — a state of total superposition encompassing all possible configurations, including states of total existence and total non-existence. Since no external observer exists in this pre-geometric state, the unique self-consistent collapse of the total superposition is self-observation: the field collapses upon itself, producing the IHC geometry. Formalised as the existence of a compact space admitting a fixed-point-free involution, this logical necessity uniquely determines: (i) ℝP⁴ topology; (ii) n=4 spacetime dimensions, via the quaternionic Hopf fibration and the uniqueness of SO(8) triality; (iii) the Ginzburg–Landau Cohesion Field as the unique dynamically stable self-referential scalar field; (iv) Clifford tori as the unique isotropic stable modes; (v) the golden ratio φ=(1+√5)/2 as the unique self-similar scaling ratio; (vi) Z₃ triality and three fermion generations; (vii) N=33 nested tori from Fibonacci spectral self-termination; and (viii) the Standard Model charged lepton masses from m(k,n) = m_P · φ⁻⁷⁸ · 33⁻⁴ · (1−α) · φᵏ · (1 ± φ⁻¹/(n×8)). Two further results are derived without free parameters. First, the 24-cell — the unique self-dual regular polytope in four dimensions — is identified as the geometric embodiment of self-observation and the origin of base-24 arithmetic in the electroweak corrections; from this structure the Weinberg angle is predicted as sin²θ_W(M_Z) = 3φ⁻¹/8 = 0.23176 (0.235% from observed), and the electron-to-Planck mass ratio as m_e/m_P = φ⁻⁷⁸ × 33⁻⁴ × (1−α) (0.004% error), where α is itself determined by the k=8 shell geometry. Second, the cosmological constant coherence factor β_coh = 6cos(π/23) is derived from the eigenvalue structure of the 22 co-rotating shells, with 23 = 2M+1 where M=11 is the Hopf factor; this closes the derivation of Ω_Λ = 0.6889 from first principles. The sole external input throughout is m_P.

Prequel of the Inverted Hypersphere Cosmology series. 18 pages, 0 figures, 11 references. Derives the complete IHC framework — including the cosmological constant, all charged lepton masses, the Weinberg angle, and the fine structure constant — from the logical impossibility of nothingness, with no free parameters beyond m_P. Includes a Python validation script (ihc_prequel_validation.py) confirming all 11 numerical claims.