Microsoft Dropped ACP for UCP in 104 Days. Identity Linking Is Why.

On January 8, 2026, Microsoft launched Copilot Checkout on ACP - OpenAI's Agentic Commerce Protocol, powered by Stripe. 104 days later, on April 22, Microsoft announced general availability of UCP feeds in Merchant Center. Target was the launch partner. The same day, Ulta Beauty went live with agentic commerce, linking 46 million loyalty members through UCP. Microsoft didn't just add a second protocol. They switched horses mid-race. The question nobody's answering clearly: what does UCP have tha