Senior Full-Stack AI Engineer

We have an existing Next.js and TypeScript enterprise document review application. We need one production-quality feature added: AI-powered contract version comparison. Users should upload an original contract and a revised contract. The system must compare them at clause level and display structured differences in the existing UI. Required stack: - Next.js and TypeScript - Node.js - Python and FastAPI - LangGraph - Anthropic Claude API Required functionality: - Upload two PDF or TXT contract versions - Extract and normalize document text - Use LangGraph to run a multi-step comparison workflow - Use Claude to identify added, removed, and modified clauses - Calculate the risk change for each modified clause - Return schema-validated structured JSON - Display clause differences, previous risk, new risk, explanation, and source evidence - Add loading, validation, failure, and retry states - Preserve the existing frontend design Expected output: - Executive change summary - Added clauses - Removed clauses - Modified clauses - Previous and new risk levels - Overall risk delta - Source text from both document versions - Recommended reviewer actions Important: - Claude must run through the Python service, not the browser - LangGraph must contain real workflow nodes, not a single wrapped Claude call - AI output must be validated using Pydantic - Do not redesign the frontend - Include setup instructions and .env.example No authentication, database, AWS deployment, or organization management is required in this step. These features will be provided by our in-house developers. Fixed budget: $200.