feat: introduce ChatConfig for automatic function calling in chat experience. This is not a breaking change, but it is in preparation of the breaking change for automatic function calling in the next major version update.

google/genai/chats.py

@@ -22,7 +22,16 @@
 from . import _transformers as t
 from . import types
 from .models import AsyncModels, Models
-from .types import Content, ContentOrDict, GenerateContentConfigOrDict, GenerateContentResponse, Part, PartUnionDict
+from .types import (
+    ChatConfig,
+    Content,
+    ContentOrDict,
+    GenerateContentConfig,
+    GenerateContentConfigOrDict,
+    GenerateContentResponse,
+    Part,
+    PartUnionDict,
+)
 
 
 if sys.version_info >= (3, 10):
@@ -104,20 +113,40 @@ def _extract_curated_history(
   return curated_history
 
 
+def _extract_generate_content_config(
+    chat_config: Optional[ChatConfig] = None,
+) -> Optional[GenerateContentConfig]:
+  """Slices a ChatConfig instance to a GenerateContentConfig instance.
+  """
+  if not chat_config:
+    return None
+
+  generate_content_config_kwargs = {
+      field: getattr(chat_config, field)
+      for field in GenerateContentConfig.model_fields
+  }
+  return GenerateContentConfig(**generate_content_config_kwargs)
+
+
 class _BaseChat:
   """Base chat session."""
 
   def __init__(
       self,
       *,
       model: str,
-      config: Optional[GenerateContentConfigOrDict] = None,
+      config: Optional[Union[GenerateContentConfigOrDict, ChatConfig]] = None,
       history: list[ContentOrDict],
   ):
     self._model = model
-    self._config = _extra_utils.get_usage_header(
+    if isinstance(config, ChatConfig):
+      self._config = _extra_utils.get_usage_header(
+          config, types.ChatConfig, usage="chat",  # type: ignore[arg-type]
+      )
+    else:
+      self._config = _extra_utils.get_usage_header(
         config, types.GenerateContentConfig, usage="chat"  # type: ignore[arg-type]
-    )
+      )
     content_models = []
     for content in history:
       if not isinstance(content, Content):
@@ -214,7 +243,7 @@ def __init__(
       *,
       modules: Models,
       model: str,
-      config: Optional[GenerateContentConfigOrDict] = None,
+      config: Optional[Union[GenerateContentConfigOrDict, ChatConfig]] = None,
       history: list[ContentOrDict],
   ):
     self._modules = modules
@@ -227,7 +256,7 @@ def __init__(
   def send_message(
       self,
       message: Union[list[PartUnionDict], PartUnionDict],
-      config: Optional[GenerateContentConfigOrDict] = None,
+      config: Optional[Union[GenerateContentConfigOrDict, ChatConfig]] = None,
   ) -> GenerateContentResponse:
     """Sends the conversation history with the additional message and returns the model's response.
 
@@ -254,6 +283,18 @@ def send_message(
       )
     input_content = t.t_content(message)
     method_config = config if config else self._config
+
+    # tmp workaround before the next major version update
+    # extract afc config from ChatConfig and merge it into GenerateContentConfig
+    if isinstance(method_config, ChatConfig):
+      afc_config = method_config.automatic_function_calling_config
+      if afc_config.enable is not None:
+        afc_config.disable = not afc_config.enable
+      gc_config = _extract_generate_content_config(method_config)
+      gc_config.automatic_function_calling = afc_config
+      method_config = gc_config
+
+
     method_config = _extra_utils.get_usage_header(
         method_config, types.GenerateContentConfig, usage="chat"  # type: ignore[arg-type]
     )
@@ -283,7 +324,7 @@ def send_message(
   def send_message_stream(
       self,
       message: Union[list[PartUnionDict], PartUnionDict],
-      config: Optional[GenerateContentConfigOrDict] = None,
+      config: Optional[Union[GenerateContentConfigOrDict, ChatConfig]] = None,
   ) -> Iterator[GenerateContentResponse]:
     """Sends the conversation history with the additional message and yields the model's response in chunks.
 
@@ -315,6 +356,17 @@ def send_message_stream(
     is_valid = True
     chunk = None
     method_config = config if config else self._config
+
+    # tmp workaround before the next major version update
+    # extract afc config from ChatConfig and merge it into GenerateContentConfig
+    if isinstance(method_config, ChatConfig):
+      afc_config = method_config.automatic_function_calling_config
+      if afc_config.enable is not None:
+        afc_config.disable = not afc_config.enable
+      gc_config = _extract_generate_content_config(method_config)
+      gc_config.automatic_function_calling = afc_config
+      method_config = gc_config
+
     method_config = _extra_utils.get_usage_header(
         method_config, types.GenerateContentConfig, usage="chat"  # type: ignore[arg-type]
     )
@@ -356,7 +408,7 @@ def create(
       self,
       *,
       model: str,
-      config: Optional[GenerateContentConfigOrDict] = None,
+      config: Optional[Union[GenerateContentConfigOrDict, ChatConfig]] = None,
       history: Optional[list[ContentOrDict]] = None,
   ) -> Chat:
     """Creates a new chat session.
@@ -385,7 +437,7 @@ def __init__(
       *,
       modules: AsyncModels,
       model: str,
-      config: Optional[GenerateContentConfigOrDict] = None,
+      config: Optional[Union[GenerateContentConfigOrDict, ChatConfig]] = None,
       history: list[ContentOrDict],
   ):
     self._modules = modules
@@ -398,7 +450,7 @@ def __init__(
   async def send_message(
       self,
       message: Union[list[PartUnionDict], PartUnionDict],
-      config: Optional[GenerateContentConfigOrDict] = None,
+      config: Optional[Union[GenerateContentConfigOrDict, ChatConfig]] = None,
   ) -> GenerateContentResponse:
     """Sends the conversation history with the additional message and returns model's response.
 
@@ -424,6 +476,17 @@ async def send_message(
       )
     input_content = t.t_content(message)
     method_config = config if config else self._config
+
+    # tmp workaround before the next major version update
+    # extract afc config from ChatConfig and merge it into GenerateContentConfig
+    if isinstance(method_config, ChatConfig):
+      afc_config = method_config.automatic_function_calling_config
+      if afc_config.enable is not None:
+        afc_config.disable = not afc_config.enable
+      gc_config = _extract_generate_content_config(method_config)
+      gc_config.automatic_function_calling = afc_config
+      method_config = gc_config
+
     method_config = _extra_utils.get_usage_header(
         method_config, types.GenerateContentConfig, usage="chat"  # type: ignore[arg-type]
     )
@@ -453,7 +516,7 @@ async def send_message(
   async def send_message_stream(
       self,
       message: Union[list[PartUnionDict], PartUnionDict],
-      config: Optional[GenerateContentConfigOrDict] = None,
+      config: Optional[Union[GenerateContentConfigOrDict, ChatConfig]] = None,
   ) -> AsyncIterator[GenerateContentResponse]:
     """Sends the conversation history with the additional message and yields the model's response in chunks.
 
@@ -482,6 +545,17 @@ async def send_message_stream(
     input_content = t.t_content(message)
 
     method_config = config if config else self._config
+
+    # tmp workaround before the next major version update
+    # extract afc config from ChatConfig and merge it into GenerateContentConfig
+    if isinstance(method_config, ChatConfig):
+      afc_config = method_config.automatic_function_calling_config
+      if afc_config.enable is not None:
+        afc_config.disable = not afc_config.enable
+      gc_config = _extract_generate_content_config(method_config)
+      gc_config.automatic_function_calling = afc_config
+      method_config = gc_config
+
     method_config = _extra_utils.get_usage_header(
         method_config, types.GenerateContentConfig, usage="chat"  # type: ignore[arg-type]
     )
@@ -529,7 +603,7 @@ def create(
       self,
       *,
       model: str,
-      config: Optional[GenerateContentConfigOrDict] = None,
+      config: Optional[Union[GenerateContentConfigOrDict, ChatConfig]] = None,
       history: Optional[list[ContentOrDict]] = None,
   ) -> AsyncChat:
     """Creates a new chat session.

google/genai/models.py

@@ -6554,6 +6554,14 @@ def generate_content(
       raise errors.UnsupportedFunctionError(
           'MCP sessions are not supported in synchronous methods.'
       )
+    if (
+        parsed_config
+        and parsed_config.automatic_function_calling
+        and parsed_config.automatic_function_calling.enable is not None
+    ):
+      parsed_config.automatic_function_calling.disable = (
+          not parsed_config.automatic_function_calling.enable
+      )
     if _extra_utils.should_disable_afc(parsed_config):
       return self._generate_content(
           model=model, contents=contents, config=parsed_config
@@ -6725,6 +6733,14 @@ def generate_content_stream(
       raise errors.UnsupportedFunctionError(
           'MCP sessions are not supported in synchronous methods.'
       )
+    if (
+        parsed_config
+        and parsed_config.automatic_function_calling
+        and parsed_config.automatic_function_calling.enable is not None
+    ):
+      parsed_config.automatic_function_calling.disable = (
+          not parsed_config.automatic_function_calling.enable
+      )
     if _extra_utils.should_disable_afc(parsed_config):
       yield from self._generate_content_stream(
           model=model, contents=contents, config=parsed_config
@@ -8762,6 +8778,14 @@ async def generate_content(
           )
       )
 
+      if (
+          final_parsed_config
+          and final_parsed_config.automatic_function_calling
+          and final_parsed_config.automatic_function_calling.enable is not None
+      ):
+        final_parsed_config.automatic_function_calling.disable = (
+            not final_parsed_config.automatic_function_calling.enable
+        )
       if _extra_utils.should_disable_afc(final_parsed_config):
         return await self._generate_content(
             model=model, contents=contents, config=final_parsed_config
@@ -9001,6 +9025,16 @@ async def stream_generator():  # type: ignore[no-untyped-def]
             )
         )
 
+        if (
+            final_parsed_config
+            and final_parsed_config.automatic_function_calling
+            and final_parsed_config.automatic_function_calling.enable
+            is not None
+        ):
+          final_parsed_config.automatic_function_calling.disable = (
+              not final_parsed_config.automatic_function_calling.enable
+          )
+
         if _extra_utils.should_disable_afc(final_parsed_config):
           response = await self._generate_content_stream(
               model=model, contents=contents, config=final_parsed_config

google/genai/tests/chats/test_send_message.py

@@ -945,3 +945,30 @@ async def test_async_server_side_mcp_tools(client):
     await chat.send_message(
         'What is the weather in San Francisco on 02/02/2026?'
     )
+
+
+def test_afc_chat_config(client):
+
+  def get_weather(location: str) -> str:
+    return f'The weather in {location} is sunny and 70 degrees.'
+
+  chat = client.chats.create(
+      model='gemini-3.1-pro-preview',
+      config=types.ChatConfig(
+          tools=[get_weather],
+          automatic_function_calling_config=types.AutomaticFunctionCallingConfig(
+              enable=True
+          ),
+      ),
+  )
+  response = chat.send_message('What is the weather in Boston?')
+  history = chat.get_history()
+  assert len(history) == 4
+  assert history[0].role == 'user'
+  assert history[1].role == 'model'
+  assert history[1].parts[0].function_call.name == 'get_weather'
+  assert history[1].parts[0].function_call.args == {'location': 'Boston'}
+  assert history[2].role == 'user'
+  assert history[2].parts[0].function_response.name == 'get_weather'
+  assert history[3].role == 'model'
+  assert '70' in history[3].parts[0].text

google/genai/types.py

@@ -5592,6 +5592,15 @@ class AutomaticFunctionCallingConfig(_common.BaseModel):
       GenerateContentResponse.automatic_function_calling_history.
       """,
   )
+  enable: Optional[bool] = Field(
+      default=None,
+      description="""Whether to enable automatic function calling.
+      If not set or set to False, will not enable automatic function calling.
+      If set to True, will enable automatic function calling.
+      NOTE: This field takes precedence over the `disable` field. the `disable`
+      field will be deprecated.
+      """,
+  )
 
 
 class AutomaticFunctionCallingConfigDict(TypedDict, total=False):
@@ -5618,6 +5627,14 @@ class AutomaticFunctionCallingConfigDict(TypedDict, total=False):
       GenerateContentResponse.automatic_function_calling_history.
       """
 
+  enable: Optional[bool]
+  """Whether to enable automatic function calling.
+      If not set or set to False, will not enable automatic function calling.
+      If set to True, will enable automatic function calling.
+      NOTE: This field takes precedence over the `disable` field. the `disable`
+      field will be deprecated.
+      """
+
 
 AutomaticFunctionCallingConfigOrDict = Union[
     AutomaticFunctionCallingConfig, AutomaticFunctionCallingConfigDict
@@ -22534,6 +22551,22 @@ class EmbedContentParametersDict(TypedDict, total=False):
 ]
 
 
+class ChatConfig(GenerateContentConfig):
+  """Configuration for chat.
+
+  This is a sub class of `GenerateContentConfig`, it supports all the
+  configurations in `GenerateContentConfig`.
+  """
+
+  automatic_function_calling_config: Optional[
+      AutomaticFunctionCallingConfig
+  ] = Field(
+      default=None,
+      description="""The configuration for automatic function calling.
+      """,
+  )
+
+
 class UserContent(Content):
   """UserContent facilitates the creation of a Content object with a user role.