The rapid evolution of artificial intelligence, secure computing, distributed systems, and human-centered technologies is reshaping the way societies create, manage, and utilize digital knowledge. Contemporary research increasingly transcends traditional disciplinary boundaries, bringing together advances in computing, engineering, healthcare, governance, cybersecurity, and intelligent systems to address complex real-world challenges.Advances in Interdisciplinary Systems & Computing 2026 presents a curated collection of scholarly contributions that reflect this convergence. The volume combines original chapters on emerging paradigms in artificial intelligence with selected peer-reviewed articles published in the Interdisciplinary Journal of Computing & AI (IJCAI). Together, these contributions provide insights into the opportunities and challenges associated with next-generation intelligent systems, privacy-preserving technologies, decentralized architectures, and advanced computing infrastructures.Part I introduces foundational perspectives on Local-First Large Language Models, resource-aware AI execution, multimodal foundation models, trustworthy artificial intelligence, and Agentic AI in trading. There are five chapters that explore emerging directions that are expected to influence the future development of AI systems across research and industry.Part II highlights human-centric applications of artificial intelligence, spanning healthcare analytics, rural water governance, intelligent design systems, and brain-computer interfaces spread across four chapters. The contributions demonstrate how AI can be leveraged to address societal needs and improve quality of life.Part III focuses on secure, privacy-preserving, and decentralized computing. There are three chapters that examine blockchain-enabled federated learning, privacy-preserving communication systems, and post-quantum secure cyber-physical environments, reflecting the growing importance of trust and resilience in digital ecosystems.Part IV explores advanced intelligent systems and computing infrastructure, including multimodal transformer architectures and GPU optimization techniques that underpin modern AI workloads and high-performance computing environments in two chapters.The chapters included in this volume collectively represent the interdisciplinary spirit that defines contemporary computing research. We hope that this book serves as a valuable resource for researchers, academicians, practitioners, policymakers, and students seeking to understand the technological innovations shaping the future of intelligent systems.