Structured Resonance as a Realization Layer of Identity Persistence_ How Recurrence, Phase, Chirality, and Coherence Implement Same-Through-Change

Abstract This paper develops a downstream realization layer for the identity-persistence stack. Prior work establishes that coherent identity persistence under transformation requires a Tier-1 regime: identity-bearing unit, state domain, admissible transformations, admissible redescriptions, identity-relevant quotient, continuation structure, invariant basis, governance order, and drift bounds. This paper asks how real systems physically, biologically, cognitively, or symbolically instantiate those roles. The proposed answer is structured resonance: recurrence-constrained dynamics in which perturbation is filtered through phase relation, invariant modes, coherence thresholds, chirality or orientation, and bounded drift. Structured resonance is not the foundation of identity persistence and is not forced at Tier-1. It is one major realization architecture for systems whose persistence depends on recurrence, oscillation, feedback, phase-locking, harmonic stability, repair loops, memory recurrence, or loss-of-lock thresholds. The paper maps the formal roles of the identity-persistence theorem onto biological organisms, DNA chirality, neural memory, spiral morphology, software artifact identity, institutions, and AI system continuity. The result is a bridge from formal identity theory to the intuition that stable emergence is perturbation made coherent by recurrence constraints.