Matter over Antimatter as a Conditional Post-diction: the Sign of the Baryon Asymmetry, a Complete Moduli Chain, and a Stratified CP-Phase Sector in an E8-Derived E6 Model

Why the universe retained matter rather than antimatter has a standard mechanism (leptogenesis) but no standard answer for its sign: in generic models the sign is set by unconstrained phases, so it is chosen rather than explained. This paper reports the closing arc of a research program in which the sign of the baryon asymmetry becomes a conditional post-diction of an E8-derived E6 framework: under declared conditions, the sign follows from a small set of already-measured Standard-Model quantities, with no adjustable sign freedom, and it comes out on the matter side. The supporting pieces are developed to the same standard: the vacuum configuration the result relies on is shown to arise dynamically rather than by assumption; the CP-phase content of the framework is organized into strata, each resolved within a stated frame; and a set of exact algebraic results ties the existence of fermion masses and the matter/antimatter choice to a single spontaneous event. The magnitude of the asymmetry is treated with the same discipline and carried to an unusual end point: it is first measured against the framework's own benchmark, then shown to be blocked at the expected source by a structural limitation, then recovered in full through a different internal channel — reaching the observed value within declared bands — and finally shown to depend on an early-universe condition that the minimal framework itself provably fails to supply. That failing grade is derived, declared, and adopted as the paper's stance, together with its priced alternatives. The framework also quantifies its strong-CP cost and identifies, in class, the sector that must cancel it; the absence of antimatter domains is obtained as a consequence of the required order of cosmological events. Six pre-registered negative results are reported alongside the positive ones, and every claim is classified by its epistemic status (derived, computed, measured, conditional, or residual input). Falsifiable consequences include a specific neutrino CP-phase branch testable by JUNO and Hyper-Kamiokande, a lower bound on the Higgs-sector parameter tan beta, a required axion sector with its role sharply constrained, and the declared early-universe condition itself. All numerical statements are script-verified; the full derivation chain, scripts, and internal analyses are available from the author on reasonable request.