diff --git a/surfsense_backend/app/services/notification_service.py b/surfsense_backend/app/services/notification_service.py
index 1788d05e1..a759f3536 100644
--- a/surfsense_backend/app/services/notification_service.py
+++ b/surfsense_backend/app/services/notification_service.py
@@ -861,6 +861,98 @@ class MentionNotificationHandler(BaseNotificationHandler):
             raise
 
 
+class CommentReplyNotificationHandler(BaseNotificationHandler):
+    """Handler for comment reply notifications."""
+
+    def __init__(self):
+        super().__init__("comment_reply")
+
+    async def find_notification_by_reply(
+        self,
+        session: AsyncSession,
+        reply_id: int,
+        user_id: UUID,
+    ) -> Notification | None:
+        query = select(Notification).where(
+            Notification.type == self.notification_type,
+            Notification.user_id == user_id,
+            Notification.notification_metadata["reply_id"].astext == str(reply_id),
+        )
+        result = await session.execute(query)
+        return result.scalar_one_or_none()
+
+    async def notify_comment_reply(
+        self,
+        session: AsyncSession,
+        user_id: UUID,
+        reply_id: int,
+        parent_comment_id: int,
+        message_id: int,
+        thread_id: int,
+        thread_title: str,
+        author_id: str,
+        author_name: str,
+        author_avatar_url: str | None,
+        author_email: str,
+        content_preview: str,
+        search_space_id: int,
+    ) -> Notification:
+        existing = await self.find_notification_by_reply(session, reply_id, user_id)
+        if existing:
+            logger.info(
+                f"Notification already exists for reply {reply_id} to user {user_id}"
+            )
+            return existing
+
+        title = f"{author_name} replied in a thread"
+        message = content_preview[:100] + ("..." if len(content_preview) > 100 else "")
+
+        metadata = {
+            "reply_id": reply_id,
+            "parent_comment_id": parent_comment_id,
+            "message_id": message_id,
+            "thread_id": thread_id,
+            "thread_title": thread_title,
+            "author_id": author_id,
+            "author_name": author_name,
+            "author_avatar_url": author_avatar_url,
+            "author_email": author_email,
+            "content_preview": content_preview[:200],
+        }
+
+        try:
+            notification = Notification(
+                user_id=user_id,
+                search_space_id=search_space_id,
+                type=self.notification_type,
+                title=title,
+                message=message,
+                notification_metadata=metadata,
+            )
+            session.add(notification)
+            await session.commit()
+            await session.refresh(notification)
+            logger.info(
+                f"Created comment_reply notification {notification.id} for user {user_id}"
+            )
+            return notification
+        except Exception as e:
+            await session.rollback()
+            if (
+                "duplicate key" in str(e).lower()
+                or "unique constraint" in str(e).lower()
+            ):
+                logger.warning(
+                    f"Duplicate notification for reply {reply_id} to user {user_id}"
+                )
+                existing = await self.find_notification_by_reply(
+                    session, reply_id, user_id
+                )
+                if existing:
+                    return existing
+            raise
+
+
 class PageLimitNotificationHandler(BaseNotificationHandler):
     """Handler for page limit exceeded notifications."""
 
@@ -959,6 +1051,7 @@ class NotificationService:
     connector_indexing = ConnectorIndexingNotificationHandler()
     document_processing = DocumentProcessingNotificationHandler()
     mention = MentionNotificationHandler()
+    comment_reply = CommentReplyNotificationHandler()
     page_limit = PageLimitNotificationHandler()
 
     @staticmethod