Fix build issue

Author: AlexITC

src/pages/[...permalink].astro

@@ -4,13 +4,16 @@ import BlogPost from '../layouts/BlogPost.astro';
 
 export async function getStaticPaths() {
 	const posts = await getCollection('blog');
-	const paths = [];
+	type BlogPermalinkPath = { params: { permalink: string } ; props: CollectionEntry<'blog'> };
+	const paths: BlogPermalinkPath[] = [];
 	
 	for (const post of posts) {
 		if (post.data.permalink) {
 			// Handle custom permalinks (Jekyll posts)
+			// [...permalink] accepts a string; Astro will match the rest param internally
+			const clean = post.data.permalink.replace(/^\/+/, '');
 			paths.push({
-				params: { permalink: post.data.permalink },
+				params: { permalink: clean },
 				props: post,
 			});
 		}

src/pages/blog/[slug].astro

@@ -4,10 +4,14 @@ import BlogPost from '../../layouts/BlogPost.astro';
 
 export async function getStaticPaths() {
 	const posts = await getCollection('blog');
-	return posts.map((post) => ({
-		params: { slug: post.data.permalink || post.id },
-		props: post,
-	}));
+	// Only generate /blog/<slug>/ routes for posts WITHOUT a custom permalink.
+	// Posts with a permalink are handled by the catch-all route at src/pages/[...permalink].astro
+	return posts
+		.filter((post) => !post.data.permalink)
+		.map((post) => ({
+			params: { slug: post.id },
+			props: post,
+		}));
 }
 type Props = CollectionEntry<'blog'>;