The Architecture of Trust: UX Design for Agentic AI in High-Stakes Systems explores how user experience design can foster trust, transparency, and human control in an era of increasingly autonomous AI. As intelligent agents become integral to healthcare, finance, transportation, defense, and other high-stakes domains, designing systems that are safe, explainable, ethical, and user-centered is more critical than ever. This book examines the evolution of agentic AI, principles of explainable and collaborative interfaces, human oversight mechanisms, ethical and regulatory considerations, and methods for evaluating trust in AI-driven experiences. Blending UX design principles with emerging AI technologies, it provides researchers, designers, developers, and decision-makers with practical frameworks for creating trustworthy human-AI interactions. The book offers valuable guidance for building intelligent systems that empower users while maintaining accountability, reliability, and confidence.