RT4 (Relational Reversibility) develops the recovery and structural stability layer of the Deficit-Fractal Governance (DFG) framework for multi-agent systems. The paper formalizes when and how system dynamics remain reversible under relational constraints, showing that recovery is not a property of individual agents but of the interaction structure that governs information flow, degradation, and coordination. It introduces relational reversibility conditions, structural failure modes, and stability boundaries that determine whether collapse propagates or becomes containable. Rather than assuming reversibility as a given, RT4 demonstrates that reversible regimes emerge only when governance preserves resolution, maintains degradation capacity, and prevents metric lock-in. This establishes recovery as a structural property and provides operational criteria for distinguishing reversible instability from irreversible collapse. The framework connects instability dynamics (RT1), measurement constraints (RT3), and governance architecture by identifying the structural conditions under which adaptive systems can restore function without external intervention.