Senior Full-Stack / AI Engineer

We are building an AI-powered concierge that turns a WhatsApp request into a verified real-world outcome. The customer-facing product lives entirely inside WhatsApp. Behind it is an agentic execution system that interprets intent, uses structured memory, connects to third-party booking/service APIs, handles failures autonomously, requires explicit confirmation before transactions, and verifies that the real-world action actually occurred. We are looking for one highly capable senior full-stack/product engineer to work closely with our founder and a part-time CTO. This is not a simple chatbot or prototype project. We want production-quality engineering from the beginning. Initial scope includes: WhatsApp Business Platform integration; LLM tool/function calling; structured user memory; PostgreSQL/Redis; booking and service-provider API integrations; deterministic confirmation and execution workflows; retries, queues and idempotency; AI-assisted failure recovery; operator dashboard; payments; Arabic/English support and voice-note processing; AWS deployment, CI/CD, logging and observability. Preferred stack: Python/FastAPI or TypeScript/NestJS for the backend, Next.js/React for the operator console, PostgreSQL, Redis and AWS. We will select one backend language before implementation and want to keep the architecture intentionally simple, avoiding unnecessary mixed-stack complexity. We especially value engineers who have built AI agents, API-heavy SaaS products, booking/marketplace systems, automation platforms, voice agents or production LLM applications. The successful candidate must be comfortable owning implementation end-to-end while working under architectural direction from our CTO. Initial engagement: paid technical trial followed by an approximately 12-week MVP build, with strong potential for an ongoing role. When applying, please show us one or two systems you personally built that are most comparable to this project. Explain what you personally implemented, the architecture used, and one difficult production failure you had to solve. Please do not send a generic portfolio or agency introduction.