Build the core Vite plugin that intercepts .md files and emits JS modules with rendered HTML, frontmatter, SEO data, and serialized tree. This is the Level 1 (static, per-file) integration — no cross-page awareness.
Implement config parsing and validation in src/index.ts
Implement per-file transform in src/transform.ts — reuses Markdoc.parse(), rune schemas from @refrakt-md/runes, serialize() from @refrakt-md/transform (requires WORK-088), createTransform(), and renderToHtml()
Wire up Vite's transform hook to intercept configured extensions
Emit JS module string with named exports
Add resolveId/load hooks for virtual module support (used by WORK-095)
Dependencies
WORK-088 — serialize() must be available from @refrakt-md/transform