Add model validation for message in ChatOutputResponse to fix markdown

src/backend/langflow/utils/schemas.py

@@ -1,7 +1,7 @@
 from typing import Dict, List, Optional, Union
 
 from langchain_core.messages import BaseMessage
-from pydantic import BaseModel
+from pydantic import BaseModel, model_validator
 
 
 class ChatOutputResponse(BaseModel):
@@ -12,7 +12,30 @@ class ChatOutputResponse(BaseModel):
     sender_name: Optional[str] = "AI"
 
     @classmethod
-    def from_message(cls, message: BaseMessage, sender: Optional[str] = "Machine", sender_name: Optional[str] = "AI"):
+    def from_message(
+        cls,
+        message: BaseMessage,
+        sender: Optional[str] = "Machine",
+        sender_name: Optional[str] = "AI",
+    ):
         """Build chat output response from message."""
         content = message.content
         return cls(message=content, sender=sender, sender_name=sender_name)
+
+    @model_validator(mode="after")
+    def validate_message(self):
+        """Validate message."""
+        # The idea here is ensure the \n in message
+        # is compliant with markdown if sender is machine
+        # so, for example:
+        # \n\n -> \n\n
+        # \n -> \n\n
+
+        if self.sender != "Machine":
+            return self
+
+        # We need to make sure we don't duplicate \n
+        # in the message
+        message = self.message.replace("\n\n", "\n")
+        self.message = message.replace("\n", "\n\n")
+        return self