A Universal Constraint from CP² Geometry: sin²θ × D = 1 — Time Density and the Structure of the Standard Model

From the integer Nc = 3 and the geometry of CP², we predict 23 Standard Model quantities to |Δ| < 0. 65%, with zero adjustable parameters. Seven predictions match to |Δ| < 0. 01%. The framework introduces a real scalar field T (time density) whose internal geometry is CP², and whose Z₂ symmetry, self-coupling λ, and geometric coupling ξ are structurally constrained by the topology of CP² to |Δ| < 0. 003%. Four longstanding problems of the Standard Model — the strong CP problem, the hierarchy problem, the origin of three generations, and color confinement — receive structural resolutions from the same geometric input. Eight falsifiable predictions are presented for CMB-S4 (~2028), DUNE (~2030), FCC-hh (~2040s), LISA, and next-generation fifth-force experiments. The package includes the paper (48 pages, 62 references, 5 figures), an independent verification script (Python 3. 8+, zero dependencies), and a Google Colab notebook with interactive visualizations. Supplementary: https: //colab. research. google. com/drive/1AeIn1gVO-tFEjICvbGQTAqTjjiZ58tb1