The world’s largest tech and retail players—Google, Walmart, Shopify, and Visa—are reshaping how digital commerce works. Their launch of the Universal Commerce Protocol (UCP) signals a transition into what can be called the execution economy : an era where AI agents don’t just influence decisions—they complete transactions . UCP is an open standard designed to let AI agents interact with a retailer or brand’s commerce systems. In practical terms, an agent can: discover prod