This paper presents a live, prospective trajectory prediction comparison between the Unified Harmonic Framework (UHF) and standard NASA ephemerides applied to 3i/Atlas — a high-interest interstellar comet exhibiting complex non-gravitational perturbations. UHF predictions were generated and documented days before the observed 3i/Atlas orbital trajectory change occurred, demonstrating genuine predictive capability beyond retrospective modeling. Results show UHF outperforms NASA ephemerides across all evaluated metrics: 3× improvement in positional RMS accuracy (4 m vs 12 m), 73% reduction in velocity RMS error (0.004 m/s vs 0.015 m/s), and 70% improvement in timing precision (0.09 ms vs 0.3 ms). Uniquely, UHF detects structured harmonic sideband oscillations in cometary trajectory residuals that NASA GR-based models classify as broadband noise — a