Ships the `portage` executable. `portage buy <url>` tries native UCP discovery first (zero credentials, works on any store that's opted in), falls back to a portage-ucp-* platform adapter only when this process already has that platform's own credentials in env (i.e. it's your own store or one you're integrated with), and otherwise says so plainly — never scrapes or session-hijacks as an anonymous shopper. `portage find` covers the no-URL case: ask an allowlist, DuckDuckGo, Brave, or a Google Programmable Search engine which stores might sell something, keep the ones answering /.well-known/ucp, and search their catalogs — documented APIs only, no SERP scraping. Depends on portage-ucp (for platform detection via Resolver) and portage-ucp-client (for the actual buy calls); no single adapter gem is a hard dependency.