ADK changes

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 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 @@ async def get_runner_async(self, app_name: str) -> Runner:
     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,
-        agent=root_agent,
+        app=agentic_app,
         artifact_service=self.artifact_service,
         session_service=self.session_service,
         memory_service=self.memory_service,
@@ -597,9 +606,10 @@ async def add_session_to_eval_set(
       invocations = evals.convert_session_to_eval_invocations(session)
 
       # Populate the session with initial session state.
-      initial_session_state = create_empty_state(
-          self.agent_loader.load_agent(app_name)
-      )
+      agent_or_app = 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,