Structural Time Flow Theory: A Minimal Framework for Late-Time Cosmology

Revision Note (v2): This version introduces a conceptual parallel in the introductory section, connecting the macroscopic structural-time postulate of TFT with recent empirical observations of the space-time limit in quantum mechanics (attosecond STM electron dynamics). The core mathematical framework and the stricter constraint-level formulation remain unchanged. Abstract: Structural Time Flow Theory (TFT) is formulated as a conditional and testable proposal in which time is treated as a structural component of spacetime rather than as a passive external parameter. This manuscript refines the minimal low-curvature background sector by placing the structural correction in the Friedmann constraint, not in a separately conserved phenomenological sector or renamed ΛCDM component. Preserving ordinary matter conservation then determines the corresponding Raychaudhuri equation. The mimetic multiplier sector is retained as a pressureless structural component, ρλ=2λ, and is interpreted as the structural pressureless/inertial mimetic mode of the homogeneous branch. In flat normalization, 1 = Ωb + Ωλ + αeff(H₀), so Ωb 0.05 and Ωλ 0.25 imply αeff(H₀) 0.70. Current Pantheon+ SN Ia and DESI BAO calibration gives an unresolved two-parameter background compression α = 0.841 ± 0.022 and H₀ = 68.94 ± 0.22 km s⁻¹Mpc⁻¹, which must be rerun with ρλ separated before being interpreted as the geometric coefficient. The ISW cross-power with deep tracers such as NVSS, computed with the growth exponent, is also discussed.