JSON Feed (https://jsonfeed.org/version/1) alongside RSS and Atom: Site.JSONFeed renders the same feedPosts newest-first items with full post HTML in content_html, the frontmatter description in summary, per-post tags, RFC 3339 date_published, and the site author/header fields. The item id and url are the post's absolute URL, so a site behind a base path feeds correct links.
- build writes feed.json on every build
- rel=alternate discovery link (application/feed+json) on every page
- mfblog serve serves it live under the base path
- tests: feed structure/header/items, file in build output, alternate link under a base path, pages stay out of the feed, serve route and media type
- README and AGENTS.md; showcase rebuilt (the sitemap diff is the pre-existing time.Now() home lastmod crossing midnight, not this feature)