Shopify's UCP CLI Reveals Where Protocol Openness Ends

Shopify's launch of @shopify/ucp-cli highlights the paradox of emerging commerce protocols: while transactions flow freely through the neutral Universal Commerce Protocol, product discovery remains locked to Shopify's index. For developers building AI agents and cross-platform commerce, this reveals that genuine interoperability still requires choosing which ecosystem to index. It's a clarifying moment for what 'open protocol' actually means when one platform controls the data gravity.