For 30 years, checkout has been a page. A form with fields for name, address, credit card number. Whether it was Amazon’s one-click patent or Apple Pay’s fingerprint, the innovation was always about making that form faster to get through. The form itself never went away. Now it is. This is the final article in a five-part series on optimizing websites for the agentic web. Part 1 covered the evolution from SEO to AAIO. Part 2 explained how to get your content cited in AI responses. Part 3 mapped the protocols forming the infrastructure layer. Part 4 got technical with how AI agents perceive your website. This article covers the commerce layer: how AI agents find products, complete purchases, and handle payments without ever loading a checkout page. In September 2025, Stripe and OpenAI launched Instant Checkout inside ChatGPT . In January 2026, Google and Shopify unveiled the Universal Commerce Protocol at the National Retail Federation conference. Two open standards.…