We propose an effective theoretical framework in which spacetime, gravity, and cosmological mass discrepancies emerge from a small primordial phase asymmetry between counterpropagating quantum degrees of freedom. In the perfectly symmetric limit, complete phasecancellation prevents the emergence of spacetime. A nonzero phase asymmetry introduces timeas phase evolution, space as phase propagation, and energy as incomplete cancellation.Weconstruct a minimal nonlinear phase Lagrangian and show that gravitational phenomenaarise as a geometric response of the phase structure to trapped energy rather than as a fundamental interaction. The extreme weakness of gravity and the smallness of the cosmologicalconstant follow naturally from a fourth-order dependence on the primordial phase asymmetryparameter.The framework predicts a cumulative, history-dependent phase effect that leads to a redshiftdependent discrepancy between dynamical and lensing mass estimates, accompanied by a smallresidual spectral shift. This yields a unified, falsifiable observational relation that distinguishesthe model from dark matter scenarios and standard ΛCDM cosmology