Omegaon Model v2.1 — Stability, Effective Field Theory Consistency, and Controlled NEC Violation

This work presents Omegaon Model v2.1, a focused technical addendum that examines the internal consistency, stability properties, and effective field theory (EFT) behaviour of the Omegaon non-singular bounce framework. Building on the numerical evolution established in Omegaon Model v2.0, this paper analyses the conditions required for a controlled violation of the null energy condition (NEC) near the bounce while maintaining ghost-free dynamics, finite sound speed, and stability of the effective degrees of freedom. Explicit expressions for the kinetic sector, stability constraints, and equation-of-state behaviour are derived and verified. The analysis demonstrates that NEC violation arises in a localized and transient regime, driven by the high-density effective sector, and does not lead to pathological behaviour or breakdown of the EFT description. The results confirm that the Omegaon bounce can be realised without fine-tuning and remains robust under moderate parameter variation. This addendum is intended as a technical consistency and stability check, complementing earlier conceptual and numerical studies of the Omegaon Model. Issues of cosmological perturbations, observational signatures, and global spacetime structure are deferred to subsequent work.