Design systems have become essential infrastructure for digital products, yet many teams struggle with token proliferation and maintenance complexity. Mise en Mode presents a paradigm shift: instead of creating endless token variations, build with intent-based tokens and apply complete "modes" to express different needs. Author Donnie D'Amato, a design systems architect with 25 years of experience, introduces a methodology where ~33 carefully named intent tokens replace hundreds of semantic tokens. Intents are named by purpose (action, surface, text), priority (primary, secondary, auxiliary), and property (backgroundColor, textColor)-creating a predictable, scalable system.The book progresses through three sections: Concept establishes the theoretical foundation of intents and modes; Develop provides practical implementation guidance including file management, delivery infrastructure, and authoring tools; Future explores inclusive design, personalization, and Large Expression Models-AI systems that generate design expressions algorithmically. With code examples in CSS Custom Properties, YAML configuration, and JavaScript infrastructure, this is both a strategic guide and an implementation manual. Whether starting a new design system or reconsidering an existing one, Mise en Mode offers a path to sustainable design architecture.