s first ChatGPT checkout in September 2025 to Walmart s Universal Commerce Protocol. Gap paired checkout with fit guidance from Bold Metrics s chief technology officer, wrote that the company was s Universal Commerce Protocol. Multi-item baskets were the gap in the first version of Instant Checkout, where Walmart The ten cases below, listed from Amazon to Walmart, show three patterns: platforms that take payment in the chat, retailers that run their own app inside the assistant, and retailers that block outside agents.