Every RAG tutorial I found looked like this: const chain = RetrievalQAChain . fromLLM ( model , vectorStore . asRetriever ()); const res = await chain . call ({ query : " what is this document about? " }); Twelve lines, a Pinecone key, a screenshot of it answering one question about one PDF, and a confident closing paragraph about "production readiness." I read four of them and still couldn't have told you what an embedding actually wa...