When institutions, technologies, and platforms co-evolve: a triadic co-evolutionary framework for public health governance in regulated digital service industries.

How do institutional constraints, technological embeddedness, and platform governance co-evolve to reconfigure the public health governance of regulated digital service industries? This article develops a triadic co-evolutionary framework-the ITP model-that integrates institutional theory, technological evolution theory, and platform ecosystem theory to address this question. The study is positioned as a theory-building, qualitatively oriented single-case analysis supported by secondary documentary evidence and extended through structured cross-national comparison; it does not report primary empirical data. Drawing on China's medical esthetics social commerce sector as a "theory-laden" extreme case-in which multi-agency public health and consumer-protection regulatory pressure, deep generative-AI (AIGC) penetration, and platforms occupying dual commercial-regulatory roles are simultaneously present-we trace the mechanisms through which the three elements interact via a "constraint-enablement-transmission" channel across three co-evolutionary phases, with explicit attention to the public-health implications of governance dynamics. Cross-national comparative evidence from Republic of Korea and the European Union is incorporated to assess the framework's conditional generalizability for health-systems governance. The analysis identifies three structurally embedded tensions that the co-evolutionary process appears to generate: a temporal disjuncture between regulatory rigidity and technological elasticity that may compromise public-health responsiveness; a structural contradiction between platform growth imperatives and public-health compliance mandates, expressed as legitimacy deficits; and a compliance-cost escalation dynamic that is consistent with a self-reinforcing feedback loop of concentrated enforcement and market fragmentation, with downstream consequences for the safety, quality, and equitable accessibility of health-related services. We translate these mechanisms into explicit public-health propositions concerning patient safety, health equity, quality of care, health misinformation, and health-system resilience, and we situate the framework against the rapidly expanding 2024-2026 literatures on trustworthy AI, AI governance, algorithmic accountability, and digital-health governance. The ITP framework advances the public-health governance literature by suggesting that these tensions are emergent properties of triadic co-evolutionary interaction-not reducible to any single element's excess-and by specifying the boundary conditions under which the framework may generalize to other public-health-relevant regulated service industries, including telemedicine, online pharmacy, digital mental health, and platform-based care delivery.