Projection-First Dark-Sector Diagnostics: Effective Stress, Lensing, and Cosmological Closure

Dark matter and dark energy are names for distinct empirical requirements, not merely for missing microscopic descriptions. A projection-first framework may suggest that unresolved source data appear as effective gravitational terms, but this suggestion becomes physical only after it produces covariant field equations and observables. This paper formulates that requirement for Modal Triplet Theory. A dark-matter realization must reproduce gravitational lensing, approximately pressureless clustering, structure growth, cosmic microwave background effects, and cluster dynamics. A dark-energy realization must produce the observed expansion history and perturbation behavior while remaining stable and compatible with local gravity. Both require a selected effective stress tensor or an explicit modified-gravity operator satisfying the Bianchi identity. Constraint load and capacity exhaustion are therefore retained as hypothesis labels, not established explanations. No current MTT result derives the required dark-sector source, halo solutions, or cosmological likelihoods.