The cosmological constant is resolved by sump relaxation: brane ZPE started at ΛPlanck and is exponentially opposed by the growing sump. The relaxation timescale is Tcosmo = f2/3 bulk/H0 = 1.61 Gyr (≈H−1 0 /9). This generates dynamical dark energy with w(z) crossing −1 at zcross ≈0.4, matching DESI DR1. v2 correction: original formula Tcosmo = r0/c for σ = 500 km/s gives 253 Gyr (wrong). Correct formula uses the G2-derived f2/3 bulk relaxation fraction.Part of the One-Octonion Brane-Bulk Framework series. Anchor DOI: 10.5281/zenodo.19120873. Community: one-octonion-brane-bulk. Author: Bharathi Dasan Jagadeesan, M.D., University of Minnesota. ORCID: 0000-0002-1143-941X.