About Us We are a bootstrapped Estonian PropTech startup building WhatsApp-native AI Experts for real estate brokers across Europe. We're not building another dashboard - we're building an AI workforce that lives where brokers already work: WhatsApp. Our system is live in production. We have paying customers. This is not a concept project - it's a running platform undergoing a surgical migration from NestJS/TypeScript to Python/LangGraph. The Role We're looking for an AI Agent Architect to own the architecture and development of our multi-agent LangGraph platform. You'll work directly with the CEO and a small team to build, extend, and maintain a production system that processes real estate conversations in real time. This is a hands-on role. You'll be writing code, designing graph architectures, and shipping features - not producing slide decks. Tech Stack Language: Python Graph engine: LangGraph (StateGraph, subgraphs, checkpointing) Web framework: FastAPI (webhooks, WebSocket) Database: PostgreSQL 17 + pgvector (state, broker data, RAG embeddings) LLM tiering: Claude Haiku (routing) → Sonnet (conversation) → Opus (analysis) via Anthropic API Observability: LangSmith (every graph execution traced) Payments: Stripe Infra: Supabase Channels: WhatsApp Business, Web Must-Haves Production LangGraph experience - You've built and deployed multi-agent systems with LangGraph StateGraphs, subgraphs, and checkpointing. Not tutorials. Production. Python async fluency - FastAPI, SQLAlchemy async, proper error handling patterns LLM application architecture - Model tiering, prompt engineering, RAG with pgvector, cost optimization PostgreSQL proficiency - Migrations, RLS, indexing, pgvector AI-assisted development - You use Claude Code, Cursor, or similar tools daily. Conversational AI understanding. Multi-turn state machines, intent routing, brand voice enforcement Security awareness - Encryption at rest, GDPR compliance, webhook verification, input guards against prompt injection Strong Pluses WhatsApp Business API integration Stripe subscription/payment flow experience Multilingual systems Experience with Strangler Fig migration patterns How We Work Small team, big autonomy. You'll have direct access to the CEO and full context on product decisions. Documentation-driven. We maintain comprehensive PRDs, architecture docs, and decision registers in Notion. AI-first development. We expect AI-assisted coding. Async-first, overlap appreciated. We're EU-based (CET timezone). Red Flags (Be Honest With Yourself) You've never deployed LangGraph to production → not ready for this role You prefer custom orchestration frameworks over LangGraph → philosophical mismatch You don't use AI coding assistants → you'll be too slow for our pace You need detailed tickets to know what to build → we need architectural thinkers You've only worked with OpenAI → we're Anthropic-native (Haiku/Sonnet/Opus) To Apply Skip the generic cover letter. Instead, tell us: One LangGraph system you built - what it did, how many agents, what went wrong, how you fixed it Your AI tooling setup - what you use for coding, how it changes your workflow Your availability - hours/week, timezone, earliest start date Your rate - hourly, in USD