Frontend Designer and Developer to build AI agent SaaS

Summary Frontend designer & developer (TypeScript/Next.js) to build AI agent SaaS. We're building a web based MVP for youth athletes: an AI chat agent product where each user gets their own isolated agent (per-user memory, data, and context). We need a frontend designer/developer to own the client side end-to-end and work with the backend engineer to integrate frontend and backend. WHAT YOU'LL BUILD - Polish wireframes, draft UIs, and concepts we've created, then develop the frontend layer from that design (Next.js/TypeScript on Vercel) - Streaming chat interface for LLM responses - Interactive in-chat widgets the agent renders via tool calls (timers, animations, custom components) - Mobile-first PWA that feels as close to a native mobile app as possible - Wiring frontend to the backend API routes MUST HAVE - AI coding tools as your primary workflow (Cursor, Claude Code, Codex, or similar) - Production experience with React, Next.js, TypeScript, and Vercel - Shipped at least one consumer mobile app or mobile-optimized website - Portfolio of mobile-first web work (PWA, chat UIs) - Comfortable building custom interactive components and integrating streaming APIs NICE TO HAVE - Experience with Vercel AI SDK or similar streaming/chat libraries - Framer Motion or similar animation experience - Experience with sensitive data / products for minors (COPPA-adjacent) DETAILS - Timeline: MVP target of 4-6 weeks - You'll work with me and backend dev directly; scope doc and wireframes are ready TO APPLY Include a link to your mobile-first portfolio and briefly describe one streaming chat UI or PWA you shipped. If it's a fit, I'll invite you to a short 15-minute intro call on Upwork before hiring.