feat: add arg to enable dft in liger (#3125)

* feat: add arg to enable dft in liger

* feat: add tests use_token_scaling

* fix: test

* fix: move check to args

src/axolotl/integrations/liger/args.py

@@ -16,7 +16,7 @@
 Module for handling LIGER input arguments.
 """
 
-from pydantic import BaseModel, model_validator
+from pydantic import BaseModel, Field, model_validator
 
 from axolotl.utils.logging import get_logger
 
@@ -35,6 +35,15 @@ class LigerArgs(BaseModel):
     liger_glu_activation: bool | None = None
     liger_cross_entropy: bool | None = None
     liger_fused_linear_cross_entropy: bool | None = None
+    liger_use_token_scaling: bool | None = Field(
+        default=None,
+        json_schema_extra={
+            "description": (
+                "Enables use_token_scaling in fused_linear_cross_entropy. "
+                "When True, each token's loss is multiplied by its predicted probability (detached from gradients)."
+            )
+        },
+    )
 
     @model_validator(mode="before")
     @classmethod
@@ -75,6 +84,18 @@ class LigerArgs(BaseModel):
             )
         return data
 
+    @model_validator(mode="before")
+    @classmethod
+    def check_liger_use_token_scaling_flce(cls, data):
+        if data.get("liger_use_token_scaling") and not data.get(
+            "liger_fused_linear_cross_entropy"
+        ):
+            raise ValueError(
+                "`liger_use_token_scaling: true` requires `liger_fused_linear_cross_entropy` enabled."
+            )
+
+        return data
+
     @model_validator(mode="after")
     def check_tensor_parallel_size_liger_fused_linear_cross_entropy(self):
         # TODO @SalmanMohammadi this is a larger fix - investigate