WhatsApp Auto-Reply & Broadcast

I need a practical solution that will both answer incoming WhatsApp messages automatically and push bulk messages to a customer list from a CSV or Google Sheet. The core idea is simple: when someone writes to our Business number, they receive an immediate, relevant reply; when we have a promotion or update, I can press a button (or schedule) to broadcast a template-approved message to thousands of saved numbers without triggering WhatsApp spam limits.

At minimum, I expect:
• A small web or desktop interface where I can edit reply rules or templates, upload contact lists, and monitor delivery/read status.
• Connection to the official WhatsApp Business API (or an equally compliant provider such as Twilio or Gupshup) so the number stays safe from banning.
• Step-by-step deployment instructions plus source code in Python, Node.js, or another widely supported language.

Please plan for sandbox testing on your side first; once it passes, I will connect my production number.