Late-Time Tilted Anisotropic Relaxation: A Bianchi Type I Model Unifying the 2025 Cosmic Dipole Anomaly and DESI Evolving Dark Energy Hints

Late-2025 observations have elevated the cosmic dipole anomaly to >5σ significance in multiple catalogs, challenging the isotropic FLRW foundation of ΛCDM. Concurrently, DESI Year-3+ data prefer a dynamical dark energy equation-of-state weakening at low redshift (~4.2σ). Emerging evidence suggests dipolar modulation in local H0 measurements. We propose a minimal tilted Bianchi Type I model with late-time anisotropic relaxation, where primordial shear (super-horizon relic) decays as σ ∝ a^{-3} but creates a transient “relaxation window” during cosmic acceleration. This geometric mechanism unifies the dipole excess, transient w_eff(z) deviation, and directional H0 variance without new fields. Predictions include dipole fade with redshift, axis alignments, and w_eff(z) contours testable with 2026 Euclid, Rubin, and DESI releases.