We built an n8n agent that reads a live Google Doc as its knowledge base on every incoming WhatsApp message. It builds a prompt from the current date, the customer's message, and the doc content, then generates a reply through OpenAI or Gemini. It also respects WhatsApp's 24 hour messaging window, checking how long it's been since the last customer contact and switching to a pre approved template message instead of a free form reply once that window has closed.