As user experience (UX) increasingly shapes the value and usability of digital products, enabling non-designers to transform their ideas into coherent UX outcomes remains an important yet challenging problem. Despite advances in AI-assisted tools, UX design still requires cross-stage reasoning across strategic, structural, and interface layers, which is often unsupported by existing systems. To address this gap, this study proposes MAUX, a layered multi-agent UX framework that structures and coordinates design reasoning through goal-driven workflows. MAUX operationalizes the five classical UX layers (strategy, scope, structure, skeleton, and surface) via LLM-driven agents grounded in human–computer interaction principles. A blackboard architecture coordinated by a Meta-Agent maintains semantic consistency across stages, enabling systematic progression from initial intent to interface realization. The framework is demonstrated through the design of Urban AirLink, a conceptual low-altitude mobility platform, and evaluated against four LLM-based baselines in a controlled user study ( N = 50 ). Results show that MAUX significantly improves design quality, structural clarity, and cross-layer goal alignment compared to baseline approaches. These findings highlight the potential of MAUX to support reasoning-centered and democratized AI-assisted UX design.