using field validator instead of model validator

src/axolotl/utils/schemas/config.py

@@ -1104,16 +1104,19 @@ class AxolotlInputConfig(
 
         return data
 
-    @model_validator(mode="before")
+    @field_validator("sequence_parallel_degree", mode="before")
     @classmethod
-    def check_sequence_parallel_config(cls, data):
-        if data.get("sequence_parallel_degree", 1) > 1:
-            if not data.get("flash_attention"):
+    def check_sequence_parallel_config(cls, value, info):
+        if not value:
+            value = 1
+
+        if value > 1:
+            if not info.data.get("flash_attention"):
                 raise ValueError(
                     "flash_attention: true must be set with sequence_parallel_degree > 1"
                 )
 
-        return data
+        return value
 
 
 class AxolotlConfigWCapabilities(AxolotlInputConfig):