This skill should be used when the user is designing, iterating, or shipping a mobile app as a solo indie developer or non-technical founder. Trigger on: "I'm making an app", "help me design an app", "review my UX", app concept pitches, problem/solution fit, user flow design, usability issues, market research, App Store positioning, onboarding design, monetization strategy, platform and stack decisions, and mobile UI direction. Socratic and framework-light. Uses training knowledge unless the user explicitly asks for live market or web research.