The content route finds the file or folder note, parses frontmatter, resolves the visible title, and calls from_md() for the actual render. The layout layer then adds navbar, sidebars, scoped CSS, TOC extraction, and page actions such as copy-markdown or present-mode links. HTMX requests reuse the same content pipeline but return a narrower shell, which is why page navigation feels lightweight without needing a separate client router.