Dark Sector Phenomena from Dynamically Emergent Spacetime Torsion

General relativity implicitly assumes that spacetime relaxes instantaneously after matter moves. Here we drop that assumption and propose a finite relaxation time: even after the source has shifted, a residual geometric memory persists and bends light as ordinary mass would, yielding the lensing signal usually attributed to dark matter. We model this memory as an effective massive vector mode with a characteristic timescale Myr set by the infrared scale of gravitational systems. Spatial gradients generate dark-matter–like rigidity, while slow late-time evolution produces dark-energy–like behavior (an effective ). We test the framework with independent probes: (i) DESI reveals an environmental dependence of the local expansion rate, with km s Mpc between low- and high-density regions (); (ii) joint MCMC fits to Cosmic Chronometers, BAO, and Pantheon+ SNe improve over CDM by ; and (iii) strong-lensing/merger systems (including El Gordo) show baryon–potential offsets consistent with geometric relaxation. A consistent scale emerges across galaxy and cluster dynamics.