Building Travel Copilots with OpenAI's Assistants API: A Practitioner's Guide to Function Calling and Persistent Threads I've spent the last eighteen months working with travel technology teams who are trying to answer one deceptively simple question: how do we build AI assistants that actually help our agents close bookings faster? Not chatbots that frustrate users with canned responses, but genuine copilots that understand context, retrieve the right information and execute real actions. The answer, I've found, lies in OpenAI's Assistants API—a framework that combines function calling, file search, and persistent conversation threads in ways that feel purpose-built for complex B2B workflows like travel agent desks. But this isn't about replacing human expertise. It's about augmenting it with tools that remember context, surface relevant policy documents, and automate the tedious lookups that consume hours of an agent's day.…