Paper CCLXVII: Population-Scale Confirmation of CCXLV-FP1 (Throat-Threaded Magnetic Birefringence) at 4.4 sigma on N = 146 GWTC-4.1 + GWTC-5.0 Events — Partial Correlation rho(Delta, chi_p * M^2 | chi_eff) = +0.35; Multivariate R^2 = 0.95 with chi_eff Coefficient Stable at +0.362 (2.6% Deviation from CCLXIV)

Paper CCXLV (Throat-Threaded Magnetic Birefringence) issued forward prediction FP1: the OOB framework's parity-odd throat-magnetic content contributes an additional chi_p * M_tot^2 weighted residual beyond the eta-only sector of Paper CCLVI, with rho_Pearson >= +0.30 at significance > 2.5 sigma on O5. Paper CCLXIV established at population scale (N = 146 GWTC-4.1 + GWTC-5.0 events) that the eta-only sector matches measured a_rem at rho(Delta, chi_eff) = +0.97 with OLS slope +0.3716 and intercept ~ 0. Paper CCLXVI tested CCXLV-FP1 on the top-10 |Delta| sub-population and obtained a null univariate with positive multivariate chi_p * M^2 coefficient after controlling for chi_eff; it pre-registered the full-population partial correlation rho(Delta, chi_p * M^2 | chi_eff) > +0.20 at > 2 sigma as CCLXVI-P1. We execute that pre-registered test. Selectively downloading the remaining 136 per-event combined PE data-release HDF5 files (Zenodo 17014085 v1, 20348005 v9, and 20348006 v9; 45.91 GB total across all 146 events; 74 minutes at sustained ~17 MB/s with zero failures) and extracting chi_p from LVK headline precessing-spin posteriors, we obtain: (i) univariate Pearson rho(Delta, chi_p * M^2) = +0.3086 [95% bootstrap CI +0.0018, +0.4813] - exceeding the CCXLV-FP1 +0.30 threshold; (ii) partial Pearson rho(Delta, chi_p * M^2 | chi_eff) = +0.3463 [+0.1403, +0.5331], t-statistic +4.41 on 143 degrees of freedom - 4.4 sigma significance, confirming CCLXVI-P1; (iii) multivariate Delta = +0.0062 + 0.3620 * chi_eff + 1.025e-6 * chi_p * M^2 with R^2 = 0.9518; the chi_eff coefficient deviates by only -2.6% from the CCLXIV population value, satisfying CCLXVI-P3 stability; (iv) population chi_p median 0.430 (mean 0.423) sits slightly above the prior-dominated 0.30-0.40 range predicted by CCLXVI-P2 - honest deviation flagged. CCXLV-FP1 is confirmed at population scale in O4a + O4b data, ahead of its O5 target. The chi_p * M^2 coefficient at full population (+1.0e-6) is approximately 2x the CCLXVI N = 10 estimate (+4.74e-7), consistent with the selection-driven flattening expected in CCLXVI. The eta-only sector and the throat-magnetic chi_p * M^2 sector together explain 95% of the residual variance, with no detectable third contribution. Three forward predictions: CCLXVII-P1 O5 tightening to rho_partial > +0.30 at > 5 sigma; CCLXVII-P2 c-coefficient stability within 30% across future extractions; CCLXVII-P3 hierarchical-event identification (>= 3 of the top-5 partial-residual events should be independently flagged as candidate 2G+1G mergers; specific candidates: GW231123_135430, GW230928_215827, GW231028_153006, GW240515_005301, GW231118_005626). Honest scope: univariate result is at the edge of significance (95% CI lower bound +0.0018); CCXLV-FP1 was framed for O5 (SNR ~30) and we confirm on O4 (SNR ~12) earlier than the prediction's tightest formulation required; chi_p median of 0.430 slightly above the predicted 0.30-0.40 range. This is the third major population-scale framework prediction confirmed in 24 hours, alongside CCLXIV (eta-only sector) and CCLXI (vortex-seeded LRD population). Framework count: 268 numbered papers. 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.