The transition from a senior individual contributor (IC) to a technical leadership role is a critical juncture in an engineer’s career, often fraught with challenges that are not purely technical. This paper examines this transition within the context of modern, complex frontend engineering landscapes, characterized by micro-frontend architectures, monorepos, and sophisticated state management systems. We argue that the deep technical mastery that propels engineers to senior IC roles is necessary but insufficient for effective leadership, creating a “competency gap” that requires deliberate and strategic mentorship. Drawing on the Dreyfus Model of Skill Acquisition, we propose a comprehensive framework for mentoring senior frontend engineers. This framework emphasizes the shift from execution to strategic planning, from code-level focus to system-level observability, and from direct implementation to architectural governance. We provide actionable strategies, including the use of Architectural Decision Records (ADRs) and “safe-to-fail” leadership environments. Furthermore, we present an expanded case study of a micro-frontend migration that illustrates the practical application of these strategies, alongside new sections detailing the role of observ-ability and design system governance as proxies for leadership development.