What does the AI do if the caller mixes French and English?

It keeps up: detection happens word by word, and if the caller code-switches — "hello, j'ai une urgence de plomberie" — the reply follows the exchange's dominant language, without restarting the conversation or asking them to choose. The summary you receive preserves the original language of mixed passages, so nothing said gets distorted. This case is common in North American cities and it's handled natively, not as a painful exception. The one limit: if the caller switches to an unsupported language, the AI says so and continues in writing in the language of first contact.