pkg:brew PURLs failed with "unsupported ecosystem: brew", although listing their versions worked. Homebrew publishes a formula's bottles as an image on its artifact upstream, which proxy mirror can already fetch, so a brew PURL is now resolved to that image and mirrored like one: the formula's JSON API gives the tag, which carries the revision and the bottles' rebuild, and --platform selects bottles like image platforms.
Listing a formula's versions returned the versioned siblings the Homebrew client adds (openssl@3.6 for openssl@3) as versions of it; they are now left out.