EchoStack — Airport Voice Rental Agent

EchoStack is a voice-first airport car-rental agent designed for travelers arriving at Dubai International Airport (DXB) and Singapore Changi Airport (SIN). Instead of completing a traditional rental form, a traveler speaks naturally about pickup time, return time, driver age, passengers, luggage, transmission, or vehicle preference. AssemblyAI’s Voice Agent API powers the real-time conversational layer, including speech recognition, turn-taking, interruption handling, reasoning, text-to-speech, and tool calling. EchoStack’s backend owns the business-critical state: it validates rental requirements, searches explicitly labeled demo inventory, returns grounded vehicle options, and creates a reservation request only after the traveler confirms the details. The agent never treats a request as a completed booking. Every new reservation enters a pending state and requires approval from an authorized human before it can become confirmed. The backend also exposes booking-status and cancellation operations so the traveler can retrieve the verified result. The MVP demonstrates a safer pattern for voice commerce: natural conversation on the front end, bounded tools and deterministic validation on the backend, and human approval for consequential actions.