diff --git a/google/genai/tests/afc/test_generate_content_stream_afc.py b/google/genai/tests/afc/test_generate_content_stream_afc.py
index 5cdb9b33f..b9ec0e282 100644
--- a/google/genai/tests/afc/test_generate_content_stream_afc.py
+++ b/google/genai/tests/afc/test_generate_content_stream_afc.py
@@ -21,6 +21,14 @@
 from ... import types
 
 
+pytestmark = [
+    pytest.mark.skipif(
+        "config.getoption('--private')",
+        reason="AFC logic in private SDK is re-written",
+    ),
+]
+
+
 TEST_NO_AFC_PART = types.Part(
     text=(
         'Okay, here is the weather in San Francisco'
diff --git a/google/genai/tests/afc/test_should_disable_afc.py b/google/genai/tests/afc/test_should_disable_afc.py
index 188bf2b57..bfc002972 100644
--- a/google/genai/tests/afc/test_should_disable_afc.py
+++ b/google/genai/tests/afc/test_should_disable_afc.py
@@ -17,9 +17,17 @@
 """Tests for should_disable_afc."""
 
 import pytest
+from .. import pytest_helper
 from ... import types
 from ..._extra_utils import should_disable_afc
 
+pytestmark = [
+    pytest.mark.skipif(
+        "config.getoption('--private')",
+        reason="AFC re-written for private SDK",
+    ),
+]
+
 
 def test_config_is_none():
   assert should_disable_afc(None) is False
diff --git a/google/genai/tests/chats/test_get_history.py b/google/genai/tests/chats/test_get_history.py
index e29862a77..8bdb88c8f 100644
--- a/google/genai/tests/chats/test_get_history.py
+++ b/google/genai/tests/chats/test_get_history.py
@@ -562,6 +562,10 @@ def test_chat_stream_with_empty_content(
   assert not chat.get_history(curated=True)
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC logic in private is re-written',
+)
 def test_chat_with_afc_history(mock_generate_content_afc_history):
   models_module = models.Models(mock_api_client)
   chats_module = chats.Chats(modules=models_module)
diff --git a/google/genai/tests/chats/test_send_message.py b/google/genai/tests/chats/test_send_message.py
index cee6bfe3c..0ec0f90b3 100644
--- a/google/genai/tests/chats/test_send_message.py
+++ b/google/genai/tests/chats/test_send_message.py
@@ -40,10 +40,16 @@
     raise e
 
 
-pytestmark = pytest_helper.setup(
-    file=__file__,
-    globals_for_file=globals(),
-)
+pytestmark = [
+    pytest_helper.setup(
+        file=__file__,
+        globals_for_file=globals(),
+    ),
+    pytest.mark.skipif(
+        "config.getoption('--private')",
+        reason="AFC re-written for private SDK",
+    ),
+]
 pytest_plugins = ('pytest_asyncio',)
 
 
diff --git a/google/genai/tests/chats/test_validate_response.py b/google/genai/tests/chats/test_validate_response.py
index 40c63094b..0ae49c406 100644
--- a/google/genai/tests/chats/test_validate_response.py
+++ b/google/genai/tests/chats/test_validate_response.py
@@ -14,8 +14,10 @@
 #
 
 
+from ... import chats
 from ... import types
-from ...chats import _validate_response
+
+_validate_response = chats._validate_response
 
 
 def test_validate_response_default_response():
diff --git a/google/genai/tests/models/test_function_call_streaming.py b/google/genai/tests/models/test_function_call_streaming.py
index 7ac83bc24..fbc3ec914 100644
--- a/google/genai/tests/models/test_function_call_streaming.py
+++ b/google/genai/tests/models/test_function_call_streaming.py
@@ -148,6 +148,11 @@
     test_method='models.generate_content_stream',
 )
 
+
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='in private it was not able to find the replay file',
+)
 def test_streaming_with_python_native_no_afc_config(client):
   """Tests streaming function calls with native python AFC without disabling AFC."""
   if not client.vertexai:
@@ -173,6 +178,10 @@ def test_streaming_with_python_native_no_afc_config(client):
   assert 'not compatible with automatic function calling (AFC)' in str(e.value)
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='in private it was not able to find the replay file',
+)
 def test_streaming_with_python_afc_disabled_false(client):
   """Tests streaming function calls with native python AFC without disabling AFC."""
   if not client.vertexai:
diff --git a/google/genai/tests/models/test_generate_content.py b/google/genai/tests/models/test_generate_content.py
index 8b20d8c66..fcf8aed5b 100644
--- a/google/genai/tests/models/test_generate_content.py
+++ b/google/genai/tests/models/test_generate_content.py
@@ -2159,6 +2159,10 @@ class Foo(BaseModel):
     )
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 def test_function(client):
   def get_weather(city: str) -> str:
     """Returns the weather in a city."""
diff --git a/google/genai/tests/models/test_generate_content_mcp.py b/google/genai/tests/models/test_generate_content_mcp.py
index 233186e88..7e3f0a219 100644
--- a/google/genai/tests/models/test_generate_content_mcp.py
+++ b/google/genai/tests/models/test_generate_content_mcp.py
@@ -105,6 +105,10 @@ async def test_mcp_tools_with_custom_headers_async(client):
   }
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC by default is disabled in private models.py',
+)
 @pytest.mark.asyncio
 async def test_mcp_tools_subsequent_calls_async(client):
   class MockMcpClientSession(McpClientSession):
diff --git a/google/genai/tests/models/test_generate_content_tools.py b/google/genai/tests/models/test_generate_content_tools.py
index 72eda55db..4be655258 100644
--- a/google/genai/tests/models/test_generate_content_tools.py
+++ b/google/genai/tests/models/test_generate_content_tools.py
@@ -838,6 +838,10 @@ def test_function_calling_without_implementation(client):
   )
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 def test_2_function(client):
   response = client.models.generate_content(
       model='gemini-2.5-flash',
@@ -852,6 +856,10 @@ def test_2_function(client):
   assert 'sunny' in response.text
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 @pytest.mark.asyncio
 async def test_2_function_async(client):
   response = await client.aio.models.generate_content(
@@ -866,7 +874,10 @@ async def test_2_function_async(client):
   assert 'Boston' in response.text
   assert 'sunny' in response.text
 
-
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 def test_automatic_function_calling_with_customized_math_rule(client):
   def customized_divide_integers(numerator: int, denominator: int) -> int:
     """Divide two integers with customized math rule."""
@@ -882,6 +893,10 @@ def customized_divide_integers(numerator: int, denominator: int) -> int:
   assert '501' in response.text
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 def test_automatic_function_calling(client):
   response = client.models.generate_content(
       model='gemini-2.5-flash',
@@ -895,6 +910,10 @@ def test_automatic_function_calling(client):
   assert '500' in response.text
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 @pytest.mark.asyncio
 async def test_automatic_function_calling_with_async_function(client):
   response = await client.aio.models.generate_content(
@@ -1006,6 +1025,10 @@ async def test_automatic_function_calling_stream_async(client):
     assert chunk.text is not None or chunk.candidates[0].finish_reason
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 def test_callable_tools_user_disable_afc(client):
   response = client.models.generate_content(
       model='gemini-2.5-flash',
@@ -1020,6 +1043,10 @@ def test_callable_tools_user_disable_afc(client):
   )
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 def test_callable_tools_user_disable_afc_with_max_remote_calls(client):
   response = client.models.generate_content(
       model='gemini-2.5-flash',
@@ -1034,7 +1061,10 @@ def test_callable_tools_user_disable_afc_with_max_remote_calls(client):
       },
   )
 
-
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 def test_callable_tools_user_disable_afc_with_max_remote_calls_negative(
     client,
 ):
@@ -1052,6 +1082,10 @@ def test_callable_tools_user_disable_afc_with_max_remote_calls_negative(
   )
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 def test_callable_tools_user_disable_afc_with_max_remote_calls_zero(client):
   response = client.models.generate_content(
       model='gemini-2.5-flash',
@@ -1066,7 +1100,10 @@ def test_callable_tools_user_disable_afc_with_max_remote_calls_zero(client):
       },
   )
 
-
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 def test_callable_tools_user_enable_afc(client):
   response = client.models.generate_content(
       model='gemini-2.5-flash',
@@ -1081,6 +1118,10 @@ def test_callable_tools_user_enable_afc(client):
   )
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 def test_callable_tools_user_enable_afc_with_max_remote_calls(client):
   response = client.models.generate_content(
       model='gemini-2.5-flash',
@@ -1096,6 +1137,10 @@ def test_callable_tools_user_enable_afc_with_max_remote_calls(client):
   )
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 def test_callable_tools_user_enable_afc_with_max_remote_calls_negative(
     client,
 ):
@@ -1113,6 +1158,10 @@ def test_callable_tools_user_enable_afc_with_max_remote_calls_negative(
   )
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 def test_callable_tools_user_enable_afc_with_max_remote_calls_zero(client):
   response = client.models.generate_content(
       model='gemini-2.5-flash',
@@ -1128,6 +1177,10 @@ def test_callable_tools_user_enable_afc_with_max_remote_calls_zero(client):
   )
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 def test_automatic_function_calling_with_exception(client):
   client.models.generate_content(
       model='gemini-2.5-flash',
@@ -1138,7 +1191,10 @@ def test_automatic_function_calling_with_exception(client):
       },
   )
 
-
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 def test_automatic_function_calling_float_without_decimal(client):
   response = client.models.generate_content(
       model='gemini-2.5-flash',
@@ -1152,6 +1208,10 @@ def test_automatic_function_calling_float_without_decimal(client):
   assert '500.0' in response.text
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 def test_automatic_function_calling_with_pydantic_model(client):
   class CityObject(pydantic.BaseModel):
     city_name: str
@@ -1175,7 +1235,10 @@ def get_weather_pydantic_model(
 
   assert 'cold' in response.text and 'Boston' in response.text
 
-
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 def test_automatic_function_calling_with_pydantic_model_in_list_type(client):
   class CityObject(pydantic.BaseModel):
     city_name: str
@@ -1211,6 +1274,10 @@ def get_weather_from_list_of_cities(
 
 
 # TODO(b/397404656): modify this test to pass in api mode
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 def test_automatic_function_calling_with_pydantic_model_in_union_type(client):
   class AnimalObject(pydantic.BaseModel):
     name: str
@@ -1258,6 +1325,10 @@ def get_information(
     assert 'cat' in response.text
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 def test_automatic_function_calling_with_union_operator(client):
   class AnimalObject(pydantic.BaseModel):
     name: str
@@ -1289,6 +1360,10 @@ def get_information(
   assert response.text
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 def test_automatic_function_calling_with_tuple_param(client):
   def output_latlng(
       latlng: tuple[float, float],
@@ -1312,6 +1387,10 @@ def output_latlng(
     sys.version_info < (3, 10),
     reason='| is only supported in Python 3.10 and above.',
 )
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 def test_automatic_function_calling_with_union_operator_return_type(client):
   def get_cheese_age(cheese: int) -> int | float:
     """
@@ -1341,6 +1420,10 @@ def get_cheese_age(cheese: int) -> int | float:
   assert '3' in response.text
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 def test_automatic_function_calling_with_parameterized_generic_union_type(
     client,
 ):
@@ -1388,6 +1471,10 @@ def test_empty_tools(client):
   )
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 def test_with_1_empty_tool(client):
   # Bad request for empty tool.
   with pytest_helper.exception_if_vertex(client, errors.ClientError):
@@ -1451,6 +1538,10 @@ async def test_vai_search_stream_async(client):
     assert 'retrieval' in str(e)
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 def test_automatic_function_calling_with_coroutine_function(client):
   async def divide_integers(a: int, b: int) -> int:
     return a // b
@@ -1466,6 +1557,10 @@ async def divide_integers(a: int, b: int) -> int:
     )
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 @pytest.mark.asyncio
 async def test_automatic_function_calling_with_coroutine_function_async(
     client,
@@ -1485,6 +1580,10 @@ async def divide_integers(a: int, b: int) -> int:
   assert '500' in response.text
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC by default is disabled in private models.py',
+)
 @pytest.mark.asyncio
 async def test_automatic_function_calling_async(client):
   def divide_integers(a: int, b: int) -> int:
@@ -1502,6 +1601,10 @@ def divide_integers(a: int, b: int) -> int:
   assert '500' in response.text
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC by default is disabled in private models.py',
+)
 @pytest.mark.asyncio
 async def test_automatic_function_calling_async_with_exception(client):
   def mystery_function(a: int, b: int) -> int:
@@ -1525,6 +1628,10 @@ def mystery_function(a: int, b: int) -> int:
   )
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC by default is disabled in private models.py',
+)
 @pytest.mark.asyncio
 async def test_automatic_function_calling_async_float_without_decimal(client):
   response = await client.aio.models.generate_content(
@@ -1539,6 +1646,10 @@ async def test_automatic_function_calling_async_float_without_decimal(client):
   assert '500.0' in response.text
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC by default is disabled in private models.py',
+)
 @pytest.mark.asyncio
 async def test_automatic_function_calling_async_with_pydantic_model(client):
   class CityObject(pydantic.BaseModel):
@@ -1566,6 +1677,10 @@ def get_weather_pydantic_model(
     assert 'cold' in response.text and 'Boston' in response.text
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC by default is disabled in private models.py',
+)
 @pytest.mark.asyncio
 async def test_automatic_function_calling_async_with_async_function(client):
   async def get_current_weather_async(city: str) -> str:
@@ -1611,6 +1726,10 @@ async def get_current_weather_async(city: str) -> str:
       assert chunk.parts[0].function_call.args['city'] == 'San Francisco'
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 def test_2_function_with_history(client):
   response = client.models.generate_content(
       model='gemini-2.5-flash',
@@ -1665,6 +1784,10 @@ def test_2_function_with_history(client):
   )
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC by default is disabled in private models.py',
+)
 @pytest.mark.asyncio
 async def test_2_function_with_history_async(client):
   response = await client.aio.models.generate_content(
@@ -1730,6 +1853,10 @@ def is_a_rabbit(self, number: int) -> str:
     return self.NAME + 'says isEven: ' + str(number % 2 == 0)
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 def test_class_method_tools(client):
   # This test is to make sure that instance method tools can be used in
   # the generate_content request.
@@ -1748,6 +1875,10 @@ def test_class_method_tools(client):
   assert 'FunctionHolder' in response.text
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 def test_disable_afc_in_any_mode(client):
   response = client.models.generate_content(
       model='gemini-2.5-flash',
@@ -1764,6 +1895,10 @@ def test_disable_afc_in_any_mode(client):
   )
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 def test_afc_once_in_any_mode(client):
   response = client.models.generate_content(
       model='gemini-2.5-flash',
@@ -1799,6 +1934,10 @@ def test_code_execution_tool(client):
   )
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 def test_afc_logs_to_logger_instance(client, caplog):
   caplog.set_level(logging.DEBUG, logger='google_genai.models')
   client.models.generate_content(
@@ -1822,6 +1961,10 @@ def test_afc_logs_to_logger_instance(client, caplog):
   assert 'Reached max remote calls' in caplog.text
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 def test_suppress_logs_with_sdk_logger(client, caplog):
   caplog.set_level(logging.DEBUG, logger='google_genai.models')
   sdk_logger = logging.getLogger('google_genai.models')
@@ -1867,6 +2010,10 @@ def test_tools_chat_curation(client, caplog):
   assert len(history) == 4
 
 
+@pytest.mark.skipif(
+    'config.getoption("--private")',
+    reason='AFC removed from private models.py',
+)
 def test_function_declaration_with_callable(client):
   response = client.models.generate_content(
       model='gemini-2.5-pro',
@@ -1883,6 +2030,7 @@ def test_function_declaration_with_callable(client):
   )
   assert response.function_calls is not None
 
+
 def test_function_declaration_with_callable_stream_now(client):
   for chunk in client.models.generate_content_stream(
       model='gemini-2.5-pro',
@@ -1896,6 +2044,7 @@ def test_function_declaration_with_callable_stream_now(client):
   ):
     pass
 
+
 @pytest.mark.asyncio
 async def test_function_declaration_with_callable_async(client):
   response = await client.aio.models.generate_content(
@@ -1928,6 +2077,7 @@ async def test_function_declaration_with_callable_async_stream(client):
     ):
       pass
 
+
 def test_server_side_mcp_only(client):
   """Test server side mcp, happy path."""
   with pytest_helper.exception_if_vertex(client, ValueError):
@@ -1948,6 +2098,7 @@ def test_server_side_mcp_only(client):
     )
     assert response.text
 
+
 @pytest.mark.asyncio
 async def test_server_side_mcp_only_async(client):
   """Test server side mcp, happy path."""
@@ -1972,6 +2123,7 @@ async def test_server_side_mcp_only_async(client):
     )
     assert response.text
 
+
 def test_server_side_mcp_only_stream(client):
   """Test server side mcp, happy path."""
   with pytest_helper.exception_if_vertex(client, ValueError):
diff --git a/google/genai/tests/private/test_send_message.py b/google/genai/tests/private/test_send_message.py
new file mode 100644
index 000000000..695d5ac57
--- /dev/null
+++ b/google/genai/tests/private/test_send_message.py
@@ -0,0 +1,30 @@
+# # Copyright 2025 Google LLC
+# #
+# # Licensed under the Apache License, Version 2.0 (the "License");
+# # you may not use this file except in compliance with the License.
+# # You may obtain a copy of the License at
+# #
+# #     http://www.apache.org/licenses/LICENSE-2.0
+# #
+# # Unless required by applicable law or agreed to in writing, software
+# # distributed under the License is distributed on an "AS IS" BASIS,
+# # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# # See the License for the specific language governing permissions and
+# # limitations under the License.
+# #
+
+# """Replay tests for private chats.send_message()."""
+
+# import pytest
+# from .. import pytest_helper
+
+# pytestmark = [
+#     pytest_helper.setup(
+#         file=__file__,
+#         globals_for_file=globals(),
+#     ),
+#     pytest.mark.skipif(
+#         "not config.getoption('--private')",
+#         reason="This test file is only intended for the private SDK",
+#     ),
+# ]