Dark Matter as a Diagnostic Closure Term in Effective Gravitational Descriptions

Dark matter is commonly introduced in gravitational modeling as an inferred, non-luminous contribution required to reconcile observed dynamics with baryonic mass distributions. This paper advances a technically conservative, non-ontological interpretation of that practice. Dark matter is treated as an effective, spatially distributed closure term in coarse-grained gravitational descriptions, introduced to preserve large-scale dynamical consistency when baryonic tracking alone is insufficient. The analysis is fully compatible with general relativity, ΛCDM practice, and effective field theory (EFT) methodology. No new degrees of freedom, forces, or field equations are proposed, and no claim is made regarding the microscopic nature of dark matter. The contribution is interpretive rather than predictive: to make explicit the closure logic that is often implicit in rotation-curve fitting, gravitational lensing reconstruction, and cosmological parameter inference. This framing clarifies the modeling role of the dark sector while leaving all ontological possibilities open.