Added datetime lambda function in config

app/models/chat_logs.py

@@ -15,7 +15,11 @@ class ChatLog(BaseModel):
 
     class Config:
         populate_by_name = True
-        json_encoders = {ObjectId: str}
+        json_encoders = {
+            ObjectId: str,
+            datetime: lambda v: v.replace(microsecond=0).isoformat() + "Z"  # "2025-10-22T21:22:27Z"
+        }
+
 
 class StarUpdate(BaseModel):
     id: str