A2UI answers one design question: what happens when you let a language model design a UI on the fly. It refuses to let the model write a single line of code. It sends a description instead, and a contract on the wire is what makes that description safe to trust. This piece follows one request all the way through: what the agent decides, what shape that decision is allowed to take, and how a renderer turns it into something on screen. Agent : decides what to show Protocol : the shape ...