LangChain Overview Build production-grade LLM applications using LangChain's composable framework. This skill covers chains, agents, retrieval-augmented generation (RAG), tool integration, memory, and deployment — using modern LCEL patterns (not legacy ). Instructions Step 1: Project Setup Determine the user's runtime (Python or TypeScript) and initialize the project: Python: TypeScript: Verify the LLM provider API key is set: Step 2: Understand LCEL (LangChain Expression Language) All modern LangChain code uses LCEL — the pipe ( ) operator for composing runnables: Key LCEL concepts: - Runnab…