This preprint presents the Step-3 sign-selection module of the Gauged Constant Vacuum-Mode (GCV) cosmological-constant programme. Treating the GR-exact radiative-stability backbone as fixed and the magnitude module as closed, the note asks whether late-time cosmological viability selects the positive branch once the residual cosmological constant is already concentrated near the observed scale. The analysis uses a minimal FRW recollapse asymmetry for Λ0\Lambda>0Λ>0, while explicitly not claiming a UV theorem for the sign, a unique cosmological measure, or a first-principles derivation of Λobs\Lambda_{\rm obs}Λobs. This Step-3 module is positioned after the radiative-stability backbone and the UV overlap-share / geometry magnitude closure. Project homepage:https://johansson.digital Project overview hub:https://github.com/gcv-framework/gcv-vacuum-energy