upgrade to astro v7

src/pages/posts.astro

@@ -19,7 +19,7 @@ const posts = await Promise.all(entries.map(async entry => {
         <ul>
             {posts.map( (p, idx) =>
                 <li>
-                    {idx > 0 && <hr></hr>}
+                    {idx > 0 && <hr />}
                     <h2>
                         <a href={`/${p.id}`} data-astro-prefetch>
                             {p.data.title}

src/plugins.ts

@@ -1,33 +1,17 @@
-import type { Root, Paragraph, PhrasingContent } from 'mdast';
-import type { VFile } from 'vfile';
-import { visit } from 'unist-util-visit';
-import { toString } from 'mdast-util-to-string';
+import { defineMdastPlugin } from 'satteri';
 
-
-export function remarkDescription() {
-    return (tree: Root, vfile: VFile) => {
-        let description: string | null = null;
-
-        visit(tree, 'paragraph', (node: Paragraph) => {
-            if (description !== null) return;
-            description = summarize(node);
-        });
-
-        // Astro exposes this as `remarkPluginFrontmatter` from render()
-        const astro = (vfile.data.astro ??= { frontmatter: {} }) as { frontmatter: Record<string, unknown> };
-        astro.frontmatter.description = description;
-    };
-}
-
-
-/**
- * Convert a paragraph node to a plain-text string, stripping any
- * MDX JSX elements (e.g. <Sidenote>) so their content doesn't
- * leak into the summary.
- */
-function summarize(par: Paragraph): string {
-    const filtered = par.children.filter(
-        (child: PhrasingContent) => !(child.type as string).startsWith('mdxJsx')
-    );
-    return toString({ type: 'paragraph', children: filtered });
-}
+export const description = defineMdastPlugin({
+    name: 'description',
+    paragraph(node, ctx) {
+        if (ctx.data.astro !== undefined) {
+            const astro = ctx.data.astro as { frontmatter: Record<string, unknown> };
+            if (astro.frontmatter.description === undefined) {
+                const filteredText = node.children
+                    .filter(c => c.type !== 'mdxJsxTextElement')
+                    .map(c => ctx.textContent(c))
+                    .join('');
+                astro.frontmatter.description = filteredText;
+            }
+        }
+    },
+})