Design a RAG Platform

Design an enterprise RAG (Retrieval-Augmented Generation) platform that serves 10M queries per day across 500+ engineering teams. The platform ingests 2M+ internal documents from Confluence, GitHub, Slack, Google Docs, and S3, lets engineers ask natural language questions, and returns accurate, cited answers grounded in internal knowledge. Handle hybrid retrieval, multi-strategy chunking, model routing for cost optimization, hallucination mitigation with citation enforcement, and continuous evaluation loops.