Agenticonstraints checkout has crossed an important threshold: what was once a demo-room thought experiment is now live across multiple major AI platforms, and the technology is reshaping how discovery, selection, payment, and post‑purchase flows are stitched together inside conversational interfaces. Over the past 12–18 months leading into early 2026, OpenAI, Google, Microsoft, Perplexity and Amazon have each moved to let AI agents not only recommend products but actively assemble carts...