A Six‑Tier Hubble Gradient: A Resolution to the Hubble Tension via Density‑Dependent Metric Contraction

The Hubble tension — a ∼10% systematic discrepancy between two independent measurement channels for the Hubble constant — remains one of the most pressing unsolved problems in modern cosmology. The standard ΛCDM model treats H₀ as a globally uniform parameter and cannot explain this systematic offset self‑consistently. Building on a previously published paradigm of the static cosmic substrate and local perturbation, this work uses substrate‑field partial differential dynamics and steady‑state Yukawa‑type metric solutions to derive quantitative intervals for a six‑tier Hubble gradient across distinct cosmic environments. Density serves as the observable proxy of the underlying field perturbation, rather than the fundamental driver of metric contraction. The proposed framework requires no early dark energy, ad‑hoc local void corrections, or freely fitted parameters; its behaviour follows naturally from homeostatic self‑reversion dynamics. We further infer that the effective Hubble constant depends on the perturbation density both at the radiation source and at the observer, which acts as a secondary correction term. The six‑tier gradient is a discretized sampling of a continuous density‑dependent flux field, providing concrete observational targets for upcoming wide‑area surveys.