Closure-Corrected Cosmology: Plateau and Inflection Signatures Beyond ΛCDM

We investigate a closure-corrected extension of ΛCDM cosmology in which deviations arise from a structural completion parameter C(a), with closure deficit ε(a) = 1 − C(a).

The effective dark energy density acquires a controlled dynamic component proportional to ε(a). A quasi-plateau regime naturally emerges when structural parameters satisfy β ≈ γ, leading to mild but structured deviations from standard ΛCDM behavior.

This model preserves the General Relativity backbone and does not modify Einstein equations. It introduces a minimal phenomenological correction term with explicit recovery in the completion limit (C → 1).

The framework provides:
- A parameter-controlled deviation space
- Explicit ΛCDM recovery
- Plateau and inflection signatures in late-time cosmology
- A conservative extension without new propagating degrees of freedom

This work does not claim to resolve the Hubble tension but provides a structurally motivated deviation framework that is observationally testable.