Index: src/routes/posts.js
===================================================================
--- src/routes/posts.js	(revision 5bf63b70700b4f2b8855d87b6e8b5cc11fd5e801)
+++ src/routes/posts.js	(revision 5a93ac05e84fc2017fb741af8a7071f46419619d)
@@ -236,5 +236,6 @@
       ActivityPubService.deliverCreate(site, {
         id: postId, slug: finalSlug, title: title || finalSlug,
-        content: cleanContent, published_at: publishedAt, created_at: now,
+        content: cleanContent, cover_image_url: cover_image_url || null,
+        published_at: publishedAt, created_at: now,
       }).catch(() => { /* best-effort */ });
     }