Author: Y. Seo (@momotarou / Japan)Role: Metanist — Human × AI Understanding ArchitectAI Collaboration: AI Understanding SupportORCID iD: https://orcid.org/0009-0005-7669-0612 Abstract This paper extends Coherence Governance Limits by introducing the framework of Synthetic Agency Structures, examining emergent configurations in which agency is neither purely human nor purely artificial but dynamically produced through system-level interactions. While traditional models assume agency as an intrinsic property of actors, the proposed framework argues that AI-integrated environments increasingly generate synthetic forms of agency arising from feedback loops, optimization regimes, and coherence-control architectures. Agency may no longer reside in entities alone. It may emerge from structure. 1. Rethinking Agency Classical assumptions treat agency as: Human intentional capacity Individual decision authority Actor-centered control Complex systems challenge this localization. 2. Defining Synthetic Agency Structures Synthetic Agency Structures refer to: Systemic configurations in which effective control, decision influence, and behavioral directionality emerge from interactions between human cognition, artificial systems, and institutional mechanisms. Agency becomes distributed. 3. Mechanisms of Agency Synthesis Synthetic agency may arise via: Algorithmic recommendation loops Optimization feedback cycles Interface-mediated decisions Signal-prioritization systems Institutional constraints Control is compositional. 4. Perception vs Operation Agents may experience: Subjective autonomy Delegated decision comfort Apparent choice freedom Despite structural influence layers. Agency perception diverges from causal architecture. 5. Stability and Instability Effects Synthetic agency structures may produce: Efficiency gains Coordination acceleration Responsibility diffusion Control ambiguity Conflict amplification Agency clarity decreases. 6. Sovereignty Implications Synthetic agency challenges: Responsibility attribution, authority boundaries, and cognitive sovereignty definitions. Governance models require revision. Conclusion Synthetic Agency Structures reframe agency as an emergent systemic property rather than a purely actor-owned attribute. Future civilization architectures may depend on explicit recognition of distributed control dynamics and synthetic agency stabilization mechanisms. ※ Series Declaration This work is part of the Understanding Capitalism series. The series explores value formation, cognitive mediation, and structural transformations of economic perception.