Change datamodel-codegen to use snake_case

Author: holtskinner

scripts/generate_types.sh

@@ -22,7 +22,7 @@ uv run datamodel-codegen \
   --input-file-type jsonschema \
   --output "$GENERATED_FILE" \
   --target-python-version 3.10 \
-  --output-model-type pydantic_v2.BaseModel \
+  --base-class a2a.utils.pydantic_base.A2ABaseModel \
   --disable-timestamp \
   --use-schema-description \
   --use-union-operator \
@@ -32,6 +32,7 @@ uv run datamodel-codegen \
   --use-one-literal-as-default \
   --class-name A2A \
   --use-standard-collections \
-  --use-subclass-enum
+  --use-subclass-enum \
+  --snake-case-field
 
 echo "Codegen finished successfully."

src/a2a/utils/pydantic_base.py

@@ -0,0 +1,12 @@
+"""A2A Pydantic Base Model with shared configuration."""
+
+from pydantic import BaseModel, ConfigDict
+
+
+class A2ABaseModel(BaseModel):
+    """Base model for all A2A types with shared configuration."""
+
+    model_config = ConfigDict(
+        populate_by_name=True,
+        arbitrary_types_allowed=True,
+    )