Cosmological Layered Gravity (CLG) is introduced as a geometric extension of General Relativity in which the effective gravitational coupling acquires a microscopic oscillatory modulation. This work develops the cosmological limit of the theory, derives the modified Friedmann equations, and analyzes the resulting oscillatory corrections to the expansion history. We perform a full perturbative stability analysis, obtain the quadratic action for scalar and tensor modes, and identify the parameter region free of ghosts and gradient instabilities. Using compiled H(z), BAO, SN, and Planck background priors, we construct a reproducible likelihood and explore the posterior with MCMC and nested sampling. The CLG corrections produce percent‑level deviations from ΛCDM, with the oscillation amplitude controlled by the geometric parameter β and frequency ω. Current data constrain β to the few‑percent level while allowing observationally relevant oscillatory signatures. All data files, covariance construction, and sampling scripts are included to ensure full reproducibility.
Michito Gatto (Fri,) studied this question.