Task. A bakery's customers write on WhatsApp, while its order bot already runs on Telegram. Two separate bots with two order lists would be hard to keep in step.
Solution. The same order bot now answers on WhatsApp as well, with one engine, one set of rules and one order database. Up to three choices show as buttons, longer ones as a list, and with more than ten options the customer can reply with a number. A customer who writes "Hi" gets the menu, and a real question goes to a person. Every message from Meta is checked by its signature, a repeated delivery never gets a double reply, and photos or voice notes do not break the order.
A whole order runs in an automated test against a fake WhatsApp API, with every message checked against WhatsApp's limits, and all 69 checks pass. There is no live number in the demo, and the bakery is invented. On a real project the WhatsApp Business account and number stay yours and I connect the bot through your access. An order bot starts at $500.
