- Introduces `markdown.processor` config to swap the default unified processor, with a new Rust‑based Sätteri option.
- Deprecates the legacy top‑level markdown.remarkPlugins, markdown.rehypePlugins, markdown.remarkRehype, markdown.gfm, and markdown.smartypants (and their MDX equivalents) slated for removal in a future major release.
- Updates internal dependencies such as @astrojs/internal‑helpers@0.10.0.