Build self-hosted AI chat assistants using CopilotKit + LangGraph. Use when implementing conversational AI interfaces with agentic backends, streaming responses, shared state between frontend and backend, or generative UI. This pattern uses NO hosted services - both CopilotKit runtime and LangGraph agent run on your own infrastructure. Triggers on requests to build chat interfaces, AI assistants, conversational agents, or integrate LangGraph with React frontends.