仅仅训练最后一轮对话

src/llamafactory/hparams/parser.py

@@ -162,6 +162,9 @@ def get_train_args(args: Optional[Dict[str, Any]] = None) -> _TRAIN_CLS:
     # Check arguments
     if finetuning_args.stage != "pt" and data_args.template is None:
         raise ValueError("Please specify which `template` to use.")
+    
+    if finetuning_args.stage == "pt" and data_args.train_last_turn_only:
+        raise ValueError("PT stage does not support `train_last_turn_only`.")
 
     if finetuning_args.stage != "sft" and training_args.predict_with_generate:
         raise ValueError("`predict_with_generate` cannot be set as True except SFT.")