Isolation-Aware Zeta-Zero Spacings via Signed Fourier Multisets: Variational–Spectral Estimates and Certified Local Blocks (v3.3r1 Research Preprint)

This research preprint consolidates isolation-aware signed Fourier multiset methods, fixed Fourier witnesses, blockwise Gram payments, a single-allocation signed residual framework, and MP9–MP21 proof-first audits for zeta-zero ordinate isolation. It preserves the earlier conditional fifty-mode and wider-spacing bounds and develops a candidate unconditional majority-isolation argument at c=0.1895. Crucially, the end-to-end proof is not yet independently verified; its validity depends on the full-domain analytic reductions, exact directed-interval certificates, arbitrary-multiplicity allocation accounting, smoothing and height transfer, and the BGST–Conrey normalization. The MP21 audit distinguishes quartet kernel positivity through 6c from kernel negativity at 8c in the five-point domain. The companion QA archive corrects a nonrigorous MP20 stress-test Gram coefficient from 2/9 to 1/9. This record is shared to enable external review, not as an established unconditional zeta-zero isolation theorem.