The supplementary file containing the calculated results data has been attached."

We present a Boltzmann-level observational analysis of an infrared-screened elastic-vacuum(EV) cosmological sector. The model is represented at linear order by a scale-dependent effectivegravitational coupling, implemented through an MGCAMB/Cobaya pipeline and tested againstPlanck 2018 temperature and polarization, Planck CMB lensing, and BAO data. The main usable posterior chain in the current package is the no-ISW/no-EG control run v284_hfix_d2_noISW.After removing a 30% burn-in, this chain gives a positive EV amplitude, A0 = 0.119+0.027−0.029 at68% credible level, with P(A0 > 0) = 1 within the sampled chain. However, the accompanyingprogress file included in this package contains only an early convergence record, and the fullconverged Drive chain should be restored before quoting this number as final. We therefore treatthis result as the current main posterior snapshot, while the fixed-shape runs g/h are interpretedas profile-likelihood diagnostics demonstrating a shallow degeneracy ridge. These results motivate growth-sensitive observables such as ISW tomography and the EG statistic as the decisiveroute to break the A0–kc–amplitude degeneracy.