feat: add warning for fp16 mixed precision training

finetune/schemas/args.py

@@ -1,5 +1,6 @@
 import argparse
 import datetime
+import logging
 from pathlib import Path
 from typing import Any, List, Literal, Tuple
 
@@ -157,6 +158,15 @@ class Args(BaseModel):
                 raise ValueError("train_resolution must be in format 'frames x height x width'")
             raise e
 
+    @field_validator("mixed_precision")
+    def validate_mixed_precision(cls, v: str, info: ValidationInfo) -> str:
+        if v == "fp16" and "cogvideox-2b" not in str(info.data.get("model_path", "")).lower():
+            logging.warning(
+                "All CogVideoX models except cogvideox-2b were trained with bfloat16. "
+                "Using fp16 precision may lead to training instability."
+            )
+        return v
+
     @classmethod
     def parse_args(cls):
         """Parse command line arguments and return Args instance"""