Fix: Add missing generate_message_id function to schemas.py

services/schemas.py

@@ -253,6 +253,12 @@ def generate_component_id(pipeline_id: str, index: int) -> str:
     return f"{pipeline_id}_{index}"
 
 
+def generate_message_id() -> str:
+    """Generate unique message ID using MongoDB ObjectId format"""
+    from bson import ObjectId
+    return str(ObjectId())
+
+
 def generate_output_id() -> str:
     """Generate unique output ID for downloads"""
     return f"output_{uuid.uuid4().hex[:12]}"