chore: Allow outputting non-acsii without escape and excludes fields in the dumped yaml files in the yaml_utils.py

Also excludes `_adk_recordings_config` for `adk conformance create` command.

PiperOrigin-RevId: 808865049

Author: Jacksunwei

src/google/adk/cli/conformance/cli_create.py

@@ -91,9 +91,15 @@ async def _create_conformance_test_files(
     dump_pydantic_to_yaml(
         updated_session,
         generated_session_file,
-        indent=2,
-        sort_keys=False,
-        exclude_none=True,
+        sort_keys=False,  # Output keys in the declaration order.
+        exclude={
+            "state": {"_adk_recordings_config": True},
+            "events": {
+                "__all__": {
+                    "actions": {"state_delta": {"_adk_recordings_config": True}}
+                }
+            },
+        },
     )
 
     return generated_session_file

src/google/adk/utils/yaml_utils.py

@@ -15,11 +15,16 @@
 from __future__ import annotations
 
 from pathlib import Path
+from typing import Optional
+from typing import TYPE_CHECKING
 from typing import Union
 
 from pydantic import BaseModel
 import yaml
 
+if TYPE_CHECKING:
+  from pydantic.main import IncEx
+
 
 def dump_pydantic_to_yaml(
     model: BaseModel,
@@ -29,6 +34,7 @@ def dump_pydantic_to_yaml(
     sort_keys: bool = True,
     exclude_none: bool = True,
     exclude_defaults: bool = True,
+    exclude: Optional[IncEx] = None,
 ) -> None:
   """Dump a Pydantic model to a YAML file with multiline strings using | style.
 
@@ -38,10 +44,14 @@ def dump_pydantic_to_yaml(
     indent: Number of spaces for indentation (default: 2).
     sort_keys: Whether to sort dictionary keys (default: True).
     exclude_none: Exclude fields with None values (default: True).
+    exclude_defaults: Exclude fields with default values (default: True).
+    exclude: Fields to exclude from the output. Can be a set of field names or
+      a nested dict for fine-grained exclusion (default: None).
   """
   model_dict = model.model_dump(
       exclude_none=exclude_none,
       exclude_defaults=exclude_defaults,
+      exclude=exclude,
       mode='json',
   )
 
@@ -74,6 +84,6 @@ def multiline_str_representer(dumper, data):
         Dumper=_MultilineDumper,
         indent=indent,
         sort_keys=sort_keys,
-        default_flow_style=False,
         width=1000000,  # Essentially disable text wraps
+        allow_unicode=True,  # Do not escape non-ascii characters.
     )

tests/unittests/utils/test_yaml_utils.py

@@ -123,3 +123,32 @@ def test_empty_list_formatting(tmp_path: Path):
 name: Test
 """
   assert yaml_file.read_text(encoding="utf-8") == expected
+
+
+def test_non_ascii_character_preservation(tmp_path: Path):
+  """Test that non-ASCII characters are preserved in YAML output."""
+  model = SimpleModel(
+      name="你好世界",  # Chinese
+      age=30,
+      active=True,
+      multiline_text="🌍 Hello World 🌏\nこんにちは世界\nHola Mundo 🌎",
+      items=["Château", "naïve", "café", "🎉"],
+  )
+  yaml_file = tmp_path / "test.yaml"
+
+  dump_pydantic_to_yaml(model, yaml_file)
+
+  assert yaml_file.read_text(encoding="utf-8") == """\
+active: true
+age: 30
+items:
+  - Château
+  - naïve
+  - café
+  - 🎉
+multiline_text: |-
+  🌍 Hello World 🌏
+  こんにちは世界
+  Hola Mundo 🌎
+name: 你好世界
+"""