Support provider-prefixed Gemini model IDs

contributing/samples/hello_world_openrouter/README.md

@@ -0,0 +1,48 @@
+# OpenRouter with LiteLLM
+
+This sample shows how to use an OpenRouter-hosted model with ADK through the
+existing LiteLLM model connector.
+
+## Setup
+
+Install ADK with optional integrations so that `LiteLlm` is available:
+
+```bash
+pip install "google-adk[extensions]"
+```
+
+Set your OpenRouter API key:
+
+```bash
+export OPENROUTER_API_KEY="..."
+```
+
+Optionally choose a model:
+
+```bash
+export OPENROUTER_MODEL="openrouter/openai/gpt-5.2"
+```
+
+Run the sample:
+
+```bash
+adk run contributing/samples/hello_world_openrouter
+```
+
+## Notes
+
+OpenRouter is used here through LiteLLM's OpenAI-compatible routing path:
+
+```python
+LiteLlm(
+    model="openrouter/openai/gpt-5.2",
+    api_key=os.getenv("OPENROUTER_API_KEY"),
+    api_base="https://openrouter.ai/api/v1",
+)
+```
+
+For Gemini models routed through OpenRouter, use OpenRouter model IDs such as
+`openrouter/google/gemini-2.5-pro:online`. ADK's built-in Google tools are
+optimized for native Gemini model connections, so verify tool compatibility for
+the routed model and provider you select.
+

contributing/samples/hello_world_openrouter/__init__.py

@@ -0,0 +1,13 @@
+# Copyright 2026 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.

contributing/samples/hello_world_openrouter/agent.py

@@ -0,0 +1,39 @@
+# Copyright 2026 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.
+
+from __future__ import annotations
+
+import os
+
+from google.adk.agents.llm_agent import Agent
+from google.adk.models.lite_llm import LiteLlm
+
+OPENROUTER_API_BASE = 'https://openrouter.ai/api/v1'
+OPENROUTER_MODEL = os.getenv('OPENROUTER_MODEL', 'openrouter/openai/gpt-5.2')
+
+
+root_agent = Agent(
+    name='openrouter_agent',
+    model=LiteLlm(
+        model=OPENROUTER_MODEL,
+        api_key=os.getenv('OPENROUTER_API_KEY'),
+        api_base=OPENROUTER_API_BASE,
+    ),
+    description='A simple ADK agent that uses OpenRouter through LiteLLM.',
+    instruction=(
+        'You are a concise assistant running through OpenRouter. Answer the'
+        ' user directly and mention when a question needs current or external'
+        ' information.'
+    ),
+)

src/google/adk/utils/model_name_utils.py

@@ -41,7 +41,8 @@ def extract_model_name(model_string: str) -> str:
 
   Args:
     model_string: Either a simple model name like "gemini-2.5-pro" or a
-      path-based model name like "projects/.../models/gemini-2.5-flash"
+      path-based model name like "projects/.../models/gemini-2.5-flash",
+      or a provider-prefixed model name like "gemini/gemini-2.5-flash".
 
   Returns:
     The extracted model name (e.g., "gemini-2.5-pro")
@@ -63,6 +64,17 @@ def extract_model_name(model_string: str) -> str:
   if model_string.startswith('models/'):
     return model_string[len('models/') :]
 
+  if model_string.startswith('projects/'):
+    return model_string
+
+  # Handle provider-prefixed LiteLLM-compatible names like
+  # "gemini/gemini-2.5-flash" or
+  # "openrouter/google/gemini-2.5-pro:online".
+  if '/' in model_string:
+    model_name = model_string.rsplit('/', 1)[1]
+    if model_name.startswith('gemini-'):
+      return model_name
+
   # If it's not a path-based model, return as-is (simple model name)
   return model_string
 

tests/unittests/tools/test_google_search_tool.py

@@ -250,6 +250,27 @@ async def test_process_llm_request_with_gemini_2_model_and_existing_tools_succee
     assert llm_request.config.tools[0] == existing_tool
     assert llm_request.config.tools[1].google_search is not None
 
+  @pytest.mark.asyncio
+  async def test_process_llm_request_with_provider_prefixed_gemini_model(
+      self,
+  ):
+    """Test processing LLM request with provider-prefixed Gemini model."""
+    tool = GoogleSearchTool()
+    tool_context = await _create_tool_context()
+
+    llm_request = LlmRequest(
+        model='openrouter/google/gemini-2.5-pro:online',
+        config=types.GenerateContentConfig(),
+    )
+
+    await tool.process_llm_request(
+        tool_context=tool_context, llm_request=llm_request
+    )
+
+    assert llm_request.config.tools is not None
+    assert len(llm_request.config.tools) == 1
+    assert llm_request.config.tools[0].google_search is not None
+
   @pytest.mark.asyncio
   async def test_process_llm_request_with_non_gemini_model_raises_error(self):
     """Test that non-Gemini model raises ValueError."""

tests/unittests/utils/test_model_name_utils.py

@@ -66,6 +66,20 @@ def test_extract_model_name_with_models_prefix(self):
     assert extract_model_name('models/gemini-2.5-pro') == 'gemini-2.5-pro'
     assert extract_model_name('models/gemini-2.5-flash') == 'gemini-2.5-flash'
 
+  def test_extract_model_name_provider_prefixed_model(self):
+    """Test extraction of provider-prefixed Gemini model names."""
+    assert extract_model_name('gemini/gemini-2.5-flash') == 'gemini-2.5-flash'
+    assert extract_model_name('vertex_ai/gemini-2.5-flash') == (
+        'gemini-2.5-flash'
+    )
+    assert (
+        extract_model_name('openrouter/google/gemini-2.5-pro:online')
+        == 'gemini-2.5-pro:online'
+    )
+    assert extract_model_name('openrouter/anthropic/claude-sonnet-4') == (
+        'openrouter/anthropic/claude-sonnet-4'
+    )
+
   def test_extract_model_name_invalid_path(self):
     """Test that invalid path formats return the original string."""
     invalid_paths = [
@@ -118,6 +132,13 @@ def test_is_gemini_model_path_based_names(self):
     non_gemini_path = 'projects/265104255505/locations/us-central1/publishers/google/models/claude-3-sonnet'
     assert is_gemini_model(non_gemini_path) is False
 
+  def test_is_gemini_model_provider_prefixed_names(self):
+    """Test Gemini model detection with provider-prefixed model names."""
+    assert is_gemini_model('gemini/gemini-2.5-flash') is True
+    assert is_gemini_model('vertex_ai/gemini-2.5-flash') is True
+    assert is_gemini_model('openrouter/google/gemini-2.5-pro:online') is True
+    assert is_gemini_model('openrouter/anthropic/claude-sonnet-4') is False
+
   def test_is_gemini_model_edge_cases(self):
     """Test edge cases for Gemini model detection."""
     # Test with None
@@ -170,6 +191,13 @@ def test_is_gemini_1_model_path_based_names(self):
     gemini_2_path = 'projects/265104255505/locations/us-central1/publishers/google/models/gemini-2.5-flash'
     assert is_gemini_1_model(gemini_2_path) is False
 
+  def test_is_gemini_1_model_provider_prefixed_names(self):
+    """Test Gemini 1.x detection with provider-prefixed model names."""
+    assert is_gemini_1_model('gemini/gemini-1.5-flash') is True
+    assert is_gemini_1_model('vertex_ai/gemini-1.5-flash') is True
+    assert is_gemini_1_model('openrouter/google/gemini-1.5-pro:online') is True
+    assert is_gemini_1_model('openrouter/google/gemini-2.5-pro') is False
+
   def test_is_gemini_1_model_edge_cases(self):
     """Test edge cases for Gemini 1.x model detection."""
     # Test with None
@@ -217,6 +245,17 @@ def test_is_gemini_2_or_above_path_based_names(self):
     gemini_3_path = 'projects/12345/locations/us-east1/publishers/google/models/gemini-3.0-pro'
     assert is_gemini_2_or_above(gemini_3_path) is True
 
+  def test_is_gemini_2_or_above_provider_prefixed_names(self):
+    """Test Gemini 2.0+ detection with provider-prefixed model names."""
+    assert is_gemini_2_or_above('gemini/gemini-2.5-flash') is True
+    assert is_gemini_2_or_above('vertex_ai/gemini-2.5-flash') is True
+    assert (
+        is_gemini_2_or_above('openrouter/google/gemini-2.5-pro:online') is True
+    )
+    assert (
+        is_gemini_2_or_above('openrouter/google/gemini-1.5-pro:online') is False
+    )
+
   def test_is_gemini_2_or_above_edge_cases(self):
     """Test edge cases for Gemini 2.0+ model detection."""
     # Test with None
@@ -245,6 +284,8 @@ def test_model_classification_consistency(self):
         'gemini-2.5-flash',
         'gemini-2.5-pro',
         'gemini-3.0-pro',
+        'gemini/gemini-2.5-flash',
+        'openrouter/google/gemini-2.5-pro:online',
         'projects/123/locations/us-central1/publishers/google/models/gemini-1.5-pro',
         'projects/123/locations/us-central1/publishers/google/models/gemini-2.5-flash',
         'projects/123/locations/us-central1/publishers/google/models/gemini-3.0-pro',