fix: lang switch

lib/blog.ts

@@ -59,7 +59,8 @@ export async function getPostBySlug(slug: string, locale: string): Promise<PostD
   try {
     const payload = await getPayload({ config: configPromise });
 
-    const { docs } = await payload.find({
+    // First try: Find in the requested locale
+    let { docs } = await payload.find({
       collection: 'posts',
       where: {
         slug: { equals: slug },
@@ -70,6 +71,38 @@ export async function getPostBySlug(slug: string, locale: string): Promise<PostD
       limit: 1,
     });
 
+    // Fallback: If not found, try searching across all locales.
+    // This happens when a user uses the static language switcher
+    // e.g. switching from /en/blog/en-slug to /de/blog/en-slug.
+    if (!docs || docs.length === 0) {
+      const { docs: crossLocaleDocs } = await payload.find({
+        collection: 'posts',
+        where: {
+          slug: { equals: slug },
+          ...(!config.showDrafts ? { _status: { equals: 'published' } } : {}),
+        },
+        locale: 'all',
+        draft: config.showDrafts,
+        limit: 1,
+      });
+
+      if (crossLocaleDocs && crossLocaleDocs.length > 0) {
+        // Fetch the found document again, but strictly in the requested locale
+        // so we get the correctly translated fields (like the localized slug)
+        const { docs: correctLocaleDocs } = await payload.find({
+          collection: 'posts',
+          where: {
+            id: { equals: crossLocaleDocs[0].id },
+          },
+          locale: locale as any,
+          draft: config.showDrafts,
+          limit: 1,
+        });
+
+        docs = correctLocaleDocs;
+      }
+    }
+
     if (!docs || docs.length === 0) return null;
 
     const doc = docs[0];