Shopify flipped the Storefront Catalog MCP server to the Universal Commerce Protocol on April 22, 2026, per the official Shopify developer changelog. The old /api/mcp endpoint and the previous search_shop_catalog and lookup tool names are deprecated. Both stay live until June 15, 2026 — then they go away. Any Hydrogen storefront, custom AI agent, or third-party integration that still calls the old endpoint after the sunset will fail. In our experience, this is one of those changes that reads as a footnote on the changelog and lands as a production incident two weeks before the deadline. The work itself is small: an endpoint rename, two tool renames, and a response-schema check against the new UCP catalog spec. The risk is that it is easy to defer until something visible breaks. For Shopify Plus engineering teams running Hydrogen, this is also not the only change in motion.…