Fix frontmatter dict conversion in documents router

services/rag-api/routers/documents.py

@@ -52,12 +52,22 @@ async def related_documents(document_id: str, limit: int = 5):
 
 
 def _row_to_doc(row: asyncpg.Record) -> DocumentResponse:
+    # Handle frontmatter - asyncpg returns JSONB as dict directly
+    fm = row['frontmatter']
+    if fm is None:
+        frontmatter = {}
+    elif isinstance(fm, dict):
+        frontmatter = fm
+    else:
+        # Fallback for unexpected types
+        frontmatter = {}
+    
     return DocumentResponse(
         id=str(row['id']),
         path=row['path'],
         title=row['title'] or '',
         content=row['content'],
-        frontmatter=dict(row['frontmatter'] or {}),
+        frontmatter=frontmatter,
         tags=list(row['tags'] or []),
         aliases=list(row['aliases'] or []),
         word_count=row['word_count'],