diff --git a/blog/bp/blog/ghost/ghost_sync.py b/blog/bp/blog/ghost/ghost_sync.py
index f1bd6fd..6bcc458 100644
--- a/blog/bp/blog/ghost/ghost_sync.py
+++ b/blog/bp/blog/ghost/ghost_sync.py
@@ -185,17 +185,25 @@ async def _upsert_post(sess: AsyncSession, gp: Dict[str, Any], author_map: Dict[
                 obj.user_id = user_id
                 await sess.flush()
 
-    # rebuild post_authors
+    # rebuild post_authors (dedup to avoid composite PK conflicts from Ghost dupes)
     await sess.execute(delete(PostAuthor).where(PostAuthor.post_id == obj.id))
+    await sess.flush()
+    seen_authors: set[int] = set()
     for idx, a in enumerate(gp.get("authors") or []):
         aa = author_map[a["id"]]
-        sess.add(PostAuthor(post_id=obj.id, author_id=aa.id, sort_order=idx))
+        if aa.id not in seen_authors:
+            seen_authors.add(aa.id)
+            sess.add(PostAuthor(post_id=obj.id, author_id=aa.id, sort_order=idx))
 
-    # rebuild post_tags
+    # rebuild post_tags (dedup similarly)
     await sess.execute(delete(PostTag).where(PostTag.post_id == obj.id))
+    await sess.flush()
+    seen_tags: set[int] = set()
     for idx, t in enumerate(gp.get("tags") or []):
         tt = tag_map[t["id"]]
-        sess.add(PostTag(post_id=obj.id, tag_id=tt.id, sort_order=idx))
+        if tt.id not in seen_tags:
+            seen_tags.add(tt.id)
+            sess.add(PostTag(post_id=obj.id, tag_id=tt.id, sort_order=idx))
 
     # Auto-create PageConfig for pages
     if obj.is_page: