fix: expose Gemini Live API client override

src/google/adk/models/google_llm.py

@@ -110,6 +110,19 @@ def api_client(self) -> Client:
 
     Use ``@property`` instead of ``@cached_property`` if you hit asyncio
     lock contention in multithreaded code.
+
+  Customizing the Live API Client:
+    The Live API path uses its own client. To set Live API-only options,
+    subclass ``Gemini`` and override the ``live_api_client`` property::
+
+        from functools import cached_property
+        from google.adk.models import Gemini
+        from google.genai import Client
+
+        class RegionalLiveGemini(Gemini):
+          @cached_property
+          def live_api_client(self) -> Client:
+            return Client(vertexai=True, location="europe-central2")
   """
 
   model: str = 'gemini-2.5-flash'
@@ -376,8 +389,7 @@ def _live_api_version(self) -> str:
       # use v1alpha for using API KEY from Google AI Studio
       return 'v1alpha'
 
-  @cached_property
-  def _live_api_client(self) -> Client:
+  def _build_live_api_client(self) -> Client:
     from google.genai import Client
 
     base_url, _ = self._base_url_and_api_version
@@ -394,6 +406,27 @@ def _live_api_client(self) -> Client:
 
     return Client(**kwargs)
 
+  def _uses_legacy_live_api_client_override(self) -> bool:
+    for cls in type(self).__mro__:
+      if '_live_api_client' in cls.__dict__:
+        return cls is not Gemini
+    return False
+
+  @cached_property
+  def live_api_client(self) -> Client:
+    """Provides the Live API client.
+
+    Subclasses can override this property to customize the ``Client`` used by
+    Live API connections.
+    """
+    if self._uses_legacy_live_api_client_override():
+      return self._live_api_client
+    return self._build_live_api_client()
+
+  @cached_property
+  def _live_api_client(self) -> Client:
+    return self.live_api_client
+
   @contextlib.asynccontextmanager
   async def connect(self, llm_request: LlmRequest) -> BaseLlmConnection:
     """Connects to the Gemini model and returns an llm connection.
@@ -455,7 +488,7 @@ async def connect(self, llm_request: LlmRequest) -> BaseLlmConnection:
     llm_request.live_connect_config.tools = llm_request.config.tools
     logger.debug('Connecting to live with llm_request:%s', llm_request)
     logger.debug('Live connect config: %s', llm_request.live_connect_config)
-    async with self._live_api_client.aio.live.connect(
+    async with self.live_api_client.aio.live.connect(
         model=llm_request.model, config=llm_request.live_connect_config
     ) as live_session:
       yield GeminiLlmConnection(

tests/unittests/models/test_google_llm.py

@@ -174,10 +174,10 @@ def test_gemini_live_api_client_creation_with_projects_prefix():
       model="projects/test-project/locations/test-location/publishers/google/models/gemini-2.5-pro"
   )
   with mock.patch("google.genai.Client", autospec=True) as mock_client:
-    _ = model._live_api_client
+    _ = model.live_api_client
     assert mock_client.call_count == 2
 
-    # Second call is for _live_api_client
+    # Second call is for live_api_client.
     _, kwargs = mock_client.call_args_list[1]
     assert kwargs["vertexai"] is True
 
@@ -732,25 +732,40 @@ def test_live_api_version_gemini_api(gemini_llm):
     assert gemini_llm._live_api_version == "v1alpha"
 
 
-def test_live_api_client_uses_api_version_from_google_base_url():
+@pytest.mark.parametrize(
+    "base_url, expected_base_url",
+    [
+        (
+            "https://generativelanguage.googleapis.com/v1alpha",
+            "https://generativelanguage.googleapis.com/",
+        ),
+        (
+            "https://generativelanguage.mtls.googleapis.com/v1alpha",
+            "https://generativelanguage.mtls.googleapis.com/",
+        ),
+    ],
+)
+def test_live_api_client_uses_api_version_from_google_base_url(
+    base_url, expected_base_url
+):
   gemini_llm = Gemini(
       model="gemini-2.5-flash",
-      base_url="https://generativelanguage.googleapis.com/v1alpha",
+      base_url=base_url,
   )
 
-  client = gemini_llm._live_api_client
+  client = gemini_llm.live_api_client
   http_options = client._api_client._http_options
 
-  assert http_options.base_url == "https://generativelanguage.googleapis.com/"
+  assert http_options.base_url == expected_base_url
   assert http_options.api_version == "v1alpha"
 
 
 def test_live_api_client_properties(gemini_llm):
-  """Test that _live_api_client is properly configured with tracking headers and API version."""
+  """Test that live_api_client is properly configured with tracking headers and API version."""
   with mock.patch.object(
       gemini_llm, "_api_backend", GoogleLLMVariant.VERTEX_AI
   ):
-    client = gemini_llm._live_api_client
+    client = gemini_llm.live_api_client
 
     # Verify that the client has the correct headers and API version
     http_options = client._api_client._http_options
@@ -763,6 +778,39 @@ def test_live_api_client_properties(gemini_llm):
       assert value in http_options.headers[key]
 
 
+def test_live_api_client_private_alias(gemini_llm):
+  assert gemini_llm._live_api_client is gemini_llm.live_api_client
+
+
+def test_live_api_client_public_override():
+  custom_client = mock.MagicMock()
+
+  class CustomGemini(Gemini):
+
+    @property
+    def live_api_client(self):
+      return custom_client
+
+  gemini_llm = CustomGemini(model="gemini-2.5-flash")
+
+  assert gemini_llm.live_api_client is custom_client
+  assert gemini_llm._live_api_client is custom_client
+
+
+def test_live_api_client_legacy_private_override():
+  custom_client = mock.MagicMock()
+
+  class CustomGemini(Gemini):
+
+    @property
+    def _live_api_client(self):
+      return custom_client
+
+  gemini_llm = CustomGemini(model="gemini-2.5-flash")
+
+  assert gemini_llm.live_api_client is custom_client
+
+
 @pytest.mark.asyncio
 async def test_connect_with_custom_headers(gemini_llm, llm_request):
   """Test that connect method updates tracking headers and API version when custom headers are provided."""
@@ -774,8 +822,8 @@ async def test_connect_with_custom_headers(gemini_llm, llm_request):
 
   mock_live_session = mock.AsyncMock()
 
-  # Mock the _live_api_client to return a mock client
-  with mock.patch.object(gemini_llm, "_live_api_client") as mock_live_client:
+  # Mock the live_api_client to return a mock client
+  with mock.patch.object(gemini_llm, "live_api_client") as mock_live_client:
     # Create a mock context manager
     class MockLiveConnect:
 
@@ -817,7 +865,7 @@ async def test_connect_without_custom_headers(gemini_llm, llm_request):
 
   mock_live_session = mock.AsyncMock()
 
-  with mock.patch.object(gemini_llm, "_live_api_client") as mock_live_client:
+  with mock.patch.object(gemini_llm, "live_api_client") as mock_live_client:
 
     class MockLiveConnect:
 
@@ -2099,7 +2147,7 @@ async def test_connect_uses_gemini_speech_config_when_request_is_none(
 
   mock_live_session = mock.AsyncMock()
 
-  with mock.patch.object(gemini_llm, "_live_api_client") as mock_live_client:
+  with mock.patch.object(gemini_llm, "live_api_client") as mock_live_client:
 
     class MockLiveConnect:
 
@@ -2147,7 +2195,7 @@ async def test_connect_uses_request_speech_config_when_gemini_is_none(
 
   mock_live_session = mock.AsyncMock()
 
-  with mock.patch.object(gemini_llm, "_live_api_client") as mock_live_client:
+  with mock.patch.object(gemini_llm, "live_api_client") as mock_live_client:
 
     class MockLiveConnect:
 
@@ -2201,7 +2249,7 @@ async def test_connect_request_gemini_config_overrides_speech_config(
 
   mock_live_session = mock.AsyncMock()
 
-  with mock.patch.object(gemini_llm, "_live_api_client") as mock_live_client:
+  with mock.patch.object(gemini_llm, "live_api_client") as mock_live_client:
 
     class MockLiveConnect:
 
@@ -2242,7 +2290,7 @@ async def test_connect_speech_config_remains_none_when_both_are_none(
 
   mock_live_session = mock.AsyncMock()
 
-  with mock.patch.object(gemini_llm, "_live_api_client") as mock_live_client:
+  with mock.patch.object(gemini_llm, "live_api_client") as mock_live_client:
 
     class MockLiveConnect: