feat: Upgrade ADK stack to use App instead in addition to root_agent

The convention:
- If some fields(like plugin) are defined both at root_agent and app, then a error will be raised.
- app code should be located within agent.py.
- an instance named app should be created

PiperOrigin-RevId: 801084463

contributing/samples/hello_world_app/__init__.py

@@ -0,0 +1,15 @@
+# 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.
+
+from . import agent

contributing/samples/hello_world_app/agent.py

@@ -0,0 +1,145 @@
+# 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.
+
+import random
+
+from google.adk import Agent
+from google.adk.agents.base_agent import BaseAgent
+from google.adk.agents.callback_context import CallbackContext
+from google.adk.apps import App
+from google.adk.models.llm_request import LlmRequest
+from google.adk.plugins.base_plugin import BasePlugin
+from google.adk.tools.tool_context import ToolContext
+from google.genai import types
+
+
+def roll_die(sides: int, tool_context: ToolContext) -> int:
+  """Roll a die and return the rolled result.
+
+  Args:
+    sides: The integer number of sides the die has.
+
+  Returns:
+    An integer of the result of rolling the die.
+  """
+  result = random.randint(1, sides)
+  if not 'rolls' in tool_context.state:
+    tool_context.state['rolls'] = []
+
+  tool_context.state['rolls'] = tool_context.state['rolls'] + [result]
+  return result
+
+
+async def check_prime(nums: list[int]) -> str:
+  """Check if a given list of numbers are prime.
+
+  Args:
+    nums: The list of numbers to check.
+
+  Returns:
+    A str indicating which number is prime.
+  """
+  primes = set()
+  for number in nums:
+    number = int(number)
+    if number <= 1:
+      continue
+    is_prime = True
+    for i in range(2, int(number**0.5) + 1):
+      if number % i == 0:
+        is_prime = False
+        break
+    if is_prime:
+      primes.add(number)
+  return (
+      'No prime numbers found.'
+      if not primes
+      else f"{', '.join(str(num) for num in primes)} are prime numbers."
+  )
+
+
+root_agent = Agent(
+    model='gemini-2.0-flash',
+    name='hello_world_agent',
+    description=(
+        'hello world agent that can roll a dice of 8 sides and check prime'
+        ' numbers.'
+    ),
+    instruction="""
+      You roll dice and answer questions about the outcome of the dice rolls.
+      You can roll dice of different sizes.
+      You can use multiple tools in parallel by calling functions in parallel(in one request and in one round).
+      It is ok to discuss previous dice roles, and comment on the dice rolls.
+      When you are asked to roll a die, you must call the roll_die tool with the number of sides. Be sure to pass in an integer. Do not pass in a string.
+      You should never roll a die on your own.
+      When checking prime numbers, call the check_prime tool with a list of integers. Be sure to pass in a list of integers. You should never pass in a string.
+      You should not check prime numbers before calling the tool.
+      When you are asked to roll a die and check prime numbers, you should always make the following two function calls:
+      1. You should first call the roll_die tool to get a roll. Wait for the function response before calling the check_prime tool.
+      2. After you get the function response from roll_die tool, you should call the check_prime tool with the roll_die result.
+        2.1 If user asks you to check primes based on previous rolls, make sure you include the previous rolls in the list.
+      3. When you respond, you must include the roll_die result from step 1.
+      You should always perform the previous 3 steps when asking for a roll and checking prime numbers.
+      You should not rely on the previous history on prime results.
+    """,
+    tools=[
+        roll_die,
+        check_prime,
+    ],
+    # planner=BuiltInPlanner(
+    #     thinking_config=types.ThinkingConfig(
+    #         include_thoughts=True,
+    #     ),
+    # ),
+    generate_content_config=types.GenerateContentConfig(
+        safety_settings=[
+            types.SafetySetting(  # avoid false alarm about rolling dice.
+                category=types.HarmCategory.HARM_CATEGORY_DANGEROUS_CONTENT,
+                threshold=types.HarmBlockThreshold.OFF,
+            ),
+        ]
+    ),
+)
+
+
+class CountInvocationPlugin(BasePlugin):
+  """A custom plugin that counts agent and tool invocations."""
+
+  def __init__(self) -> None:
+    """Initialize the plugin with counters."""
+    super().__init__(name='count_invocation')
+    self.agent_count: int = 0
+    self.tool_count: int = 0
+    self.llm_request_count: int = 0
+
+  async def before_agent_callback(
+      self, *, agent: BaseAgent, callback_context: CallbackContext
+  ) -> None:
+    """Count agent runs."""
+    self.agent_count += 1
+    print(f'[Plugin] Agent run count: {self.agent_count}')
+
+  async def before_model_callback(
+      self, *, callback_context: CallbackContext, llm_request: LlmRequest
+  ) -> None:
+    """Count LLM requests."""
+    self.llm_request_count += 1
+    print(f'[Plugin] LLM request count: {self.llm_request_count}')
+
+
+app = App(
+    name='hello_world_app',
+    root_agent=root_agent,
+    plugins=[CountInvocationPlugin()],
+)

contributing/samples/hello_world_app/main.py

@@ -0,0 +1,103 @@
+# 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.
+
+import asyncio
+import time
+
+import agent
+from dotenv import load_dotenv
+from google.adk.agents.run_config import RunConfig
+from google.adk.cli.utils import logs
+from google.adk.runners import InMemoryRunner
+from google.adk.sessions.session import Session
+from google.genai import types
+
+load_dotenv(override=True)
+logs.log_to_tmp_folder()
+
+
+async def main():
+  app_name = 'my_app'
+  user_id_1 = 'user1'
+  runner = InMemoryRunner(
+      agent=agent.root_agent,
+      app_name=app_name,
+  )
+  session_11 = await runner.session_service.create_session(
+      app_name=app_name, user_id=user_id_1
+  )
+
+  async def run_prompt(session: Session, new_message: str):
+    content = types.Content(
+        role='user', parts=[types.Part.from_text(text=new_message)]
+    )
+    print('** User says:', content.model_dump(exclude_none=True))
+    async for event in runner.run_async(
+        user_id=user_id_1,
+        session_id=session.id,
+        new_message=content,
+    ):
+      if event.content.parts and event.content.parts[0].text:
+        print(f'** {event.author}: {event.content.parts[0].text}')
+
+  async def run_prompt_bytes(session: Session, new_message: str):
+    content = types.Content(
+        role='user',
+        parts=[
+            types.Part.from_bytes(
+                data=str.encode(new_message), mime_type='text/plain'
+            )
+        ],
+    )
+    print('** User says:', content.model_dump(exclude_none=True))
+    async for event in runner.run_async(
+        user_id=user_id_1,
+        session_id=session.id,
+        new_message=content,
+        run_config=RunConfig(save_input_blobs_as_artifacts=True),
+    ):
+      if event.content.parts and event.content.parts[0].text:
+        print(f'** {event.author}: {event.content.parts[0].text}')
+
+  async def check_rolls_in_state(rolls_size: int):
+    session = await runner.session_service.get_session(
+        app_name=app_name, user_id=user_id_1, session_id=session_11.id
+    )
+    assert len(session.state['rolls']) == rolls_size
+    for roll in session.state['rolls']:
+      assert roll > 0 and roll <= 100
+
+  start_time = time.time()
+  print('Start time:', start_time)
+  print('------------------------------------')
+  await run_prompt(session_11, 'Hi')
+  await run_prompt(session_11, 'Roll a die with 100 sides')
+  await check_rolls_in_state(1)
+  await run_prompt(session_11, 'Roll a die again with 100 sides.')
+  await check_rolls_in_state(2)
+  await run_prompt(session_11, 'What numbers did I got?')
+  await run_prompt_bytes(session_11, 'Hi bytes')
+  print(
+      await runner.artifact_service.list_artifact_keys(
+          app_name=app_name, user_id=user_id_1, session_id=session_11.id
+      )
+  )
+  end_time = time.time()
+  print('------------------------------------')
+  print('End time:', end_time)
+  print('Total time:', end_time - start_time)
+
+
+if __name__ == '__main__':
+  asyncio.run(main())

src/google/adk/apps/__init__.py

@@ -0,0 +1,19 @@
+# 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.
+
+from .app import App
+
+__all__ = [
+    'App',
+]

src/google/adk/apps/app.py

@@ -0,0 +1,52 @@
+# 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.
+from __future__ import annotations
+
+from abc import ABC
+from typing import Optional
+
+from pydantic import BaseModel
+from pydantic import ConfigDict
+from pydantic import Field
+
+from ..agents.base_agent import BaseAgent
+from ..plugins.base_plugin import BasePlugin
+from ..utils.feature_decorator import experimental
+
+
+@experimental
+class App(BaseModel):
+  """Represents an LLM-backed agentic application.
+
+  An `App` is the top-level container for an agentic system powered by LLMs.
+  It manages a root agent (`root_agent`), which serves as the root of an agent
+  tree, enabling coordination and communication across all agents in the
+  hierarchy.
+  The `plugins` are application-wide components that provide shared capabilities
+  and services to the entire system.
+  """
+
+  model_config = ConfigDict(
+      arbitrary_types_allowed=True,
+      extra="forbid",
+  )
+
+  name: str
+  """The name of the application."""
+
+  root_agent: BaseAgent
+  """The root agent in the application. One app can only have one root agent."""
+
+  plugins: list[BasePlugin] = Field(default_factory=list)
+  """The plugins in the application."""

src/google/adk/cli/adk_web_server.py

@@ -50,10 +50,12 @@ from typing_extensions import override
 from watchdog.observers import Observer
 
 from . import agent_graph
+from ..agents.base_agent import BaseAgent
 from ..agents.live_request_queue import LiveRequest
 from ..agents.live_request_queue import LiveRequestQueue
 from ..agents.run_config import RunConfig
 from ..agents.run_config import StreamingMode
+from ..apps import App
 from ..artifacts.base_artifact_service import BaseArtifactService
 from ..auth.credential_service.base_credential_service import BaseCredentialService
 from ..errors.not_found_error import NotFoundError
@@ -305,10 +307,17 @@ class AdkWebServer:
     envs.load_dotenv_for_agent(os.path.basename(app_name), self.agents_dir)
     if app_name in self.runner_dict:
       return self.runner_dict[app_name]
-    root_agent = self.agent_loader.load_agent(app_name)
+    agent_or_app = self.agent_loader.load_agent(app_name)
+    agentic_app = None
+    if isinstance(agent_or_app, BaseAgent):
+      agentic_app = App(
+          name=app_name,
+          root_agent=agent_or_app,
+      )
+    else:
+      agentic_app = agent_or_app
     runner = Runner(
-        app_name=app_name,
+        app=agentic_app,
-        agent=root_agent,
         artifact_service=self.artifact_service,
         session_service=self.session_service,
         memory_service=self.memory_service,
@@ -597,9 +606,10 @@ class AdkWebServer:
       invocations = evals.convert_session_to_eval_invocations(session)
 
       # Populate the session with initial session state.
-      initial_session_state = create_empty_state(
+      agent_or_app = self.agent_loader.load_agent(app_name)
-          self.agent_loader.load_agent(app_name)
+      if isinstance(agent_or_app, App):
-      )
+        agent_or_app = agent_or_app.root_agent
+      initial_session_state = create_empty_state(agent_or_app)
 
       new_eval_case = EvalCase(
           eval_id=req.eval_id,

src/google/adk/cli/cli.py

@@ -16,12 +16,15 @@ from __future__ import annotations
 
 from datetime import datetime
 from typing import Optional
+from typing import Union
 
 import click
 from google.genai import types
 from pydantic import BaseModel
 
+from ..agents.base_agent import BaseAgent
 from ..agents.llm_agent import LlmAgent
+from ..apps.app import App
 from ..artifacts.base_artifact_service import BaseArtifactService
 from ..artifacts.in_memory_artifact_service import InMemoryArtifactService
 from ..auth.credential_service.base_credential_service import BaseCredentialService
@@ -43,15 +46,19 @@ class InputFile(BaseModel):
 async def run_input_file(
     app_name: str,
     user_id: str,
-    root_agent: LlmAgent,
+    agent_or_app: Union[LlmAgent, App],
     artifact_service: BaseArtifactService,
     session_service: BaseSessionService,
     credential_service: BaseCredentialService,
     input_path: str,
 ) -> Session:
+  app = (
+      agent_or_app
+      if isinstance(agent_or_app, App)
+      else App(name=app_name, root_agent=agent_or_app)
+  )
   runner = Runner(
-      app_name=app_name,
+      app=app,
-      agent=root_agent,
       artifact_service=artifact_service,
       session_service=session_service,
       credential_service=credential_service,
@@ -79,15 +86,19 @@ async def run_input_file(
 
 
 async def run_interactively(
-    root_agent: LlmAgent,
+    root_agent_or_app: Union[LlmAgent, App],
     artifact_service: BaseArtifactService,
     session: Session,
     session_service: BaseSessionService,
     credential_service: BaseCredentialService,
 ) -> None:
+  app = (
+      root_agent_or_app
+      if isinstance(root_agent_or_app, App)
+      else App(name=session.app_name, root_agent=root_agent_or_app)
+  )
   runner = Runner(
-      app_name=session.app_name,
+      app=app,
-      agent=root_agent,
       artifact_service=artifact_service,
       session_service=session_service,
       credential_service=credential_service,
@@ -154,7 +165,7 @@ async def run_cli(
     session = await run_input_file(
         app_name=agent_folder_name,
         user_id=user_id,
-        root_agent=root_agent,
+        agent_or_app=root_agent,
         artifact_service=artifact_service,
         session_service=session_service,
         credential_service=credential_service,

src/google/adk/cli/utils/agent_loader.py

@@ -20,6 +20,7 @@ import os
 from pathlib import Path
 import sys
 from typing import Optional
+from typing import Union
 
 from pydantic import ValidationError
 from typing_extensions import override
@@ -27,6 +28,7 @@ from typing_extensions import override
 from . import envs
 from ...agents import config_agent_utils
 from ...agents.base_agent import BaseAgent
+from ...apps.app import App
 from ...utils.feature_decorator import experimental
 from .base_agent_loader import BaseAgentLoader
 
@@ -50,19 +52,25 @@ class AgentLoader(BaseAgentLoader):
   def __init__(self, agents_dir: str):
     self.agents_dir = agents_dir.rstrip("/")
     self._original_sys_path = None
-    self._agent_cache: dict[str, BaseAgent] = {}
+    self._agent_cache: dict[str, Union[BaseAgent, App]] = {}
 
   def _load_from_module_or_package(
       self, agent_name: str
-  ) -> Optional[BaseAgent]:
+  ) -> Optional[Union[BaseAgent, App]]:
     # Load for case: Import "{agent_name}" (as a package or module)
     # Covers structures:
     #   a) agents_dir/{agent_name}.py (with root_agent in the module)
     #   b) agents_dir/{agent_name}/__init__.py (with root_agent in the package)
     try:
       module_candidate = importlib.import_module(agent_name)
+      # Check for "app" first, then "root_agent"
+      if hasattr(module_candidate, "app") and isinstance(
+          module_candidate.app, App
+      ):
+        logger.debug("Found app in %s", agent_name)
+        return module_candidate.app
       # Check for "root_agent" directly in "{agent_name}" module/package
-      if hasattr(module_candidate, "root_agent"):
+      elif hasattr(module_candidate, "root_agent"):
         logger.debug("Found root_agent directly in %s", agent_name)
         if isinstance(module_candidate.root_agent, BaseAgent):
           return module_candidate.root_agent
@@ -96,12 +104,20 @@ class AgentLoader(BaseAgentLoader):
 
     return None
 
-  def _load_from_submodule(self, agent_name: str) -> Optional[BaseAgent]:
+  def _load_from_submodule(
+      self, agent_name: str
+  ) -> Optional[Union[BaseAgent], App]:
     # Load for case: Import "{agent_name}.agent" and look for "root_agent"
     # Covers structure: agents_dir/{agent_name}/agent.py (with root_agent defined in the module)
     try:
       module_candidate = importlib.import_module(f"{agent_name}.agent")
-      if hasattr(module_candidate, "root_agent"):
+      # Check for "app" first, then "root_agent"
+      if hasattr(module_candidate, "app") and isinstance(
+          module_candidate.app, App
+      ):
+        logger.debug("Found app in %s.agent", agent_name)
+        return module_candidate.app
+      elif hasattr(module_candidate, "root_agent"):
         logger.info("Found root_agent in %s.agent", agent_name)
         if isinstance(module_candidate.root_agent, BaseAgent):
           return module_candidate.root_agent
@@ -161,7 +177,7 @@ class AgentLoader(BaseAgentLoader):
       ) + e.args[1:]
       raise e
 
-  def _perform_load(self, agent_name: str) -> BaseAgent:
+  def _perform_load(self, agent_name: str) -> Union[BaseAgent, App]:
     """Internal logic to load an agent"""
     # Add self.agents_dir to sys.path
     if self.agents_dir not in sys.path:
@@ -192,16 +208,16 @@ class AgentLoader(BaseAgentLoader):
     )
 
   @override
-  def load_agent(self, agent_name: str) -> BaseAgent:
+  def load_agent(self, agent_name: str) -> Union[BaseAgent, App]:
     """Load an agent module (with caching & .env) and return its root_agent."""
     if agent_name in self._agent_cache:
       logger.debug("Returning cached agent for %s (async)", agent_name)
       return self._agent_cache[agent_name]
 
     logger.debug("Loading agent %s - not in cache.", agent_name)
-    agent = self._perform_load(agent_name)
+    agent_or_app = self._perform_load(agent_name)
-    self._agent_cache[agent_name] = agent
+    self._agent_cache[agent_name] = agent_or_app
-    return agent
+    return agent_or_app
 
   @override
   def list_agents(self) -> list[str]:

src/google/adk/cli/utils/base_agent_loader.py

@@ -18,15 +18,17 @@ from __future__ import annotations
 
 from abc import ABC
 from abc import abstractmethod
+from typing import Union
 
 from ...agents.base_agent import BaseAgent
+from ...apps.app import App
 
 
 class BaseAgentLoader(ABC):
   """Abstract base class for agent loaders."""
 
   @abstractmethod
-  def load_agent(self, agent_name: str) -> BaseAgent:
+  def load_agent(self, agent_name: str) -> Union[BaseAgent, App]:
     """Loads an instance of an agent with the given name."""
 
   @abstractmethod

src/google/adk/runners.py

@@ -34,6 +34,7 @@ from .agents.invocation_context import new_invocation_context_id
 from .agents.live_request_queue import LiveRequestQueue
 from .agents.llm_agent import LlmAgent
 from .agents.run_config import RunConfig
+from .apps.app import App
 from .artifacts.base_artifact_service import BaseArtifactService
 from .artifacts.in_memory_artifact_service import InMemoryArtifactService
 from .auth.credential_service.base_credential_service import BaseCredentialService
@@ -91,8 +92,9 @@ class Runner:
   def __init__(
       self,
       *,
-      app_name: str,
+      app: Optional[App] = None,
-      agent: BaseAgent,
+      app_name: Optional[str] = None,
+      agent: Optional[BaseAgent] = None,
       plugins: Optional[List[BasePlugin]] = None,
       artifact_service: Optional[BaseArtifactService] = None,
       session_service: BaseSessionService,
@@ -101,23 +103,85 @@ class Runner:
   ):
     """Initializes the Runner.
 
+    Developers should provide either an `app` instance or both `app_name` and
+    `agent`. Providing a mix of `app` and `app_name`/`agent` will result in a
+    `ValueError`. Providing `app` is the recommended way to create a runner.
+
     Args:
-        app_name: The application name of the runner.
+        app_name: The application name of the runner. Required if `app` is not
-        agent: The root agent to run.
+          provided.
-        plugins: A list of plugins for the runner.
+        agent: The root agent to run. Required if `app` is not provided.
+        app: An optional `App` instance. If provided, `app_name` and `agent`
+          should not be specified.
+        plugins: Deprecated. A list of plugins for the runner. Please use the
+          `app` argument to provide plugins instead.
         artifact_service: The artifact service for the runner.
         session_service: The session service for the runner.
         memory_service: The memory service for the runner.
         credential_service: The credential service for the runner.
+
+    Raises:
+        ValueError: If `app` is provided along with `app_name` or `plugins`, or
+          if `app` is not provided but either `app_name` or `agent` is missing.
     """
-    self.app_name = app_name
+    self.app_name, self.agent, plugins = self._validate_runner_params(
-    self.agent = agent
+        app, app_name, agent, plugins
+    )
     self.artifact_service = artifact_service
     self.session_service = session_service
     self.memory_service = memory_service
     self.credential_service = credential_service
     self.plugin_manager = PluginManager(plugins=plugins)
 
+  def _validate_runner_params(
+      self,
+      app: Optional[App],
+      app_name: Optional[str],
+      agent: Optional[BaseAgent],
+      plugins: Optional[List[BasePlugin]],
+  ) -> tuple[str, BaseAgent, Optional[List[BasePlugin]]]:
+    """Validates and extracts runner parameters.
+
+    Args:
+        app: An optional `App` instance.
+        app_name: The application name of the runner.
+        agent: The root agent to run.
+        plugins: A list of plugins for the runner.
+
+    Returns:
+        A tuple containing (app_name, agent, plugins).
+
+    Raises:
+        ValueError: If parameters are invalid.
+    """
+    if app:
+      if app_name:
+        raise ValueError(
+            'When app is provided, app_name should not be provided.'
+        )
+      if agent:
+        raise ValueError('When app is provided, agent should not be provided.')
+      if plugins:
+        raise ValueError(
+            'When app is provided, plugins should not be provided and should be'
+            ' provided in the app instead.'
+        )
+      app_name = app.name
+      agent = app.root_agent
+      plugins = app.plugins
+    elif not app_name or not agent:
+      raise ValueError(
+          'Either app or both app_name and agent must be provided.'
+      )
+
+    if plugins:
+      warnings.warn(
+          'The `plugins` argument is deprecated. Please use the `app` argument'
+          ' to provide plugins instead.',
+          DeprecationWarning,
+      )
+    return app_name, agent, plugins
+
   def run(
       self,
       *,
@@ -656,10 +720,11 @@ class InMemoryRunner(Runner):
 
   def __init__(
       self,
-      agent: BaseAgent,
+      agent: Optional[BaseAgent] = None,
       *,
-      app_name: str = 'InMemoryRunner',
+      app_name: Optional[str] = 'InMemoryRunner',
       plugins: Optional[list[BasePlugin]] = None,
+      app: Optional[App] = None,
   ):
     """Initializes the InMemoryRunner.
 
@@ -674,6 +739,7 @@ class InMemoryRunner(Runner):
         agent=agent,
         artifact_service=InMemoryArtifactService(),
         plugins=plugins,
+        app=app,
         session_service=self._in_memory_session_service,
         memory_service=InMemoryMemoryService(),
     )

tests/unittests/cli/utils/test_cli.py

@@ -26,6 +26,7 @@ from typing import List
 from typing import Tuple
 
 import click
+from google.adk.agents.base_agent import BaseAgent
 import google.adk.cli.cli as cli
 import pytest
 
@@ -130,12 +131,12 @@ async def test_run_input_file_outputs(
   artifact_service = cli.InMemoryArtifactService()
   session_service = cli.InMemorySessionService()
   credential_service = cli.InMemoryCredentialService()
-  dummy_root = types.SimpleNamespace(name="root")
+  dummy_root = BaseAgent(name="root")
 
   session = await cli.run_input_file(
       app_name="app",
       user_id="user",
-      root_agent=dummy_root,
+      agent_or_app=dummy_root,
       artifact_service=artifact_service,
       session_service=session_service,
       credential_service=credential_service,
@@ -205,7 +206,7 @@ async def test_run_interactively_whitespace_and_exit(
   sess = await session_service.create_session(app_name="dummy", user_id="u")
   artifact_service = cli.InMemoryArtifactService()
   credential_service = cli.InMemoryCredentialService()
-  root_agent = types.SimpleNamespace(name="root")
+  root_agent = BaseAgent(name="root")
 
   # fake user input: blank -> 'hello' -> 'exit'
   answers = iter(["  ", "hello", "exit"])