Use when designing new screens, redesigning existing UI, creating visual concepts, or improving interfaces in Nicolify. Executes a 7-phase creative Design Thinking workflow: defines user personas, frames problems, audits existing components (Shadcn UI + Tailwind CSS v4 + FSD architecture), researches SaaS UI patterns, proposes multiple distinct layout paradigms with ASCII wireframes and HTML mockups, iterates through dialogue, and delivers a complete UI-SPEC.md with component trees, data flow, responsive behavior, and interaction patterns — all following Nicolify's design tokens and codebase conventions. Triggers: 'diseña', 'rediseña', 'nueva pantalla', 'concepto visual', 'propuesta de diseño', 'UX', 'layout', 'prototipo', 'mejora la interfaz', 'wireframe', 'mockup', 'esquema de color', 'componentes de pantalla'.