adk-python/src/google/adk/runners.py

# 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

import asyncio
import logging
import queue
import threading
from typing import AsyncGenerator, Generator, Optional

from deprecated import deprecated
from google.genai import types

from .agents.active_streaming_tool import ActiveStreamingTool
from .agents.base_agent import BaseAgent
from .agents.invocation_context import InvocationContext
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 .agents.run_config import StreamingMode
from .artifacts.base_artifact_service import BaseArtifactService
from .artifacts.in_memory_artifact_service import InMemoryArtifactService
from .events.event import Event
from .memory.base_memory_service import BaseMemoryService
from .memory.in_memory_memory_service import InMemoryMemoryService
from .sessions.base_session_service import BaseSessionService
from .sessions.in_memory_session_service import InMemorySessionService
from .sessions.session import Session
from .telemetry import tracer
from .tools.built_in_code_execution_tool import built_in_code_execution

logger = logging.getLogger(__name__)


class Runner:
  """The Runner class is used to run agents.

  It manages the execution of an agent within a session, handling message
  processing, event generation, and interaction with various services like
  artifact storage, session management, and memory.

  Attributes:
      app_name: The application name of the runner.
      agent: The root agent to run.
      artifact_service: The artifact service for the runner.
      session_service: The session service for the runner.
      memory_service: The memory service for the runner.
  """

  app_name: str
  """The app name of the runner."""
  agent: BaseAgent
  """The root agent to run."""
  artifact_service: Optional[BaseArtifactService] = None
  """The artifact service for the runner."""
  session_service: BaseSessionService
  """The session service for the runner."""
  memory_service: Optional[BaseMemoryService] = None
  """The memory service for the runner."""

  def __init__(
      self,
      *,
      app_name: str,
      agent: BaseAgent,
      artifact_service: Optional[BaseArtifactService] = None,
      session_service: BaseSessionService,
      memory_service: Optional[BaseMemoryService] = None,
  ):
    """Initializes the Runner.

    Args:
        app_name: The application name of the runner.
        agent: The root agent to run.
        artifact_service: The artifact service for the runner.
        session_service: The session service for the runner.
        memory_service: The memory service for the runner.
    """
    self.app_name = app_name
    self.agent = agent
    self.artifact_service = artifact_service
    self.session_service = session_service
    self.memory_service = memory_service

  def run(
      self,
      *,
      user_id: str,
      session_id: str,
      new_message: types.Content,
      run_config: RunConfig = RunConfig(),
  ) -> Generator[Event, None, None]:
    """Runs the agent.

    NOTE: This sync interface is only for local testing and convenience purpose.
    Consider using `run_async` for production usage.

    Args:
      user_id: The user ID of the session.
      session_id: The session ID of the session.
      new_message: A new message to append to the session.
      run_config: The run config for the agent.

    Yields:
      The events generated by the agent.
    """
    event_queue = queue.Queue()

    async def _invoke_run_async():
      try:
        async for event in self.run_async(
            user_id=user_id,
            session_id=session_id,
            new_message=new_message,
            run_config=run_config,
        ):
          event_queue.put(event)
      finally:
        event_queue.put(None)

    def _asyncio_thread_main():
      try:
        asyncio.run(_invoke_run_async())
      finally:
        event_queue.put(None)

    thread = threading.Thread(target=_asyncio_thread_main)
    thread.start()

    # consumes and re-yield the events from background thread.
    while True:
      event = event_queue.get()
      if event is None:
        break
      else:
        yield event

    thread.join()

  async def run_async(
      self,
      *,
      user_id: str,
      session_id: str,
      new_message: types.Content,
      run_config: RunConfig = RunConfig(),
  ) -> AsyncGenerator[Event, None]:
    """Main entry method to run the agent in this runner.

    Args:
      user_id: The user ID of the session.
      session_id: The session ID of the session.
      new_message: A new message to append to the session.
      run_config: The run config for the agent.

    Yields:
      The events generated by the agent.
    """
    with tracer.start_as_current_span('invocation'):
      session = self.session_service.get_session(
          app_name=self.app_name, user_id=user_id, session_id=session_id
      )
      if not session:
        raise ValueError(f'Session not found: {session_id}')

      invocation_context = self._new_invocation_context(
          session,
          new_message=new_message,
          run_config=run_config,
      )
      root_agent = self.agent

      if new_message:
        await self._append_new_message_to_session(
            session,
            new_message,
            invocation_context,
            run_config.save_input_blobs_as_artifacts,
        )

      invocation_context.agent = self._find_agent_to_run(session, root_agent)
      async for event in invocation_context.agent.run_async(invocation_context):
        if not event.partial:
          self.session_service.append_event(session=session, event=event)
        yield event

  async def _append_new_message_to_session(
      self,
      session: Session,
      new_message: types.Content,
      invocation_context: InvocationContext,
      save_input_blobs_as_artifacts: bool = False,
  ):
    """Appends a new message to the session.

    Args:
        session: The session to append the message to.
        new_message: The new message to append.
        invocation_context: The invocation context for the message.
        save_input_blobs_as_artifacts: Whether to save input blobs as artifacts.
    """
    if not new_message.parts:
      raise ValueError('No parts in the new_message.')

    if self.artifact_service and save_input_blobs_as_artifacts:
      # The runner directly saves the artifacts (if applicable) in the
      # user message and replaces the artifact data with a file name
      # placeholder.
      for i, part in enumerate(new_message.parts):
        if part.inline_data is None:
          continue
        file_name = f'artifact_{invocation_context.invocation_id}_{i}'
        await self.artifact_service.save_artifact(
            app_name=self.app_name,
            user_id=session.user_id,
            session_id=session.id,
            filename=file_name,
            artifact=part,
        )
        new_message.parts[i] = types.Part(
            text=f'Uploaded file: {file_name}. It is saved into artifacts'
        )
    # Appends only. We do not yield the event because it's not from the model.
    event = Event(
        invocation_id=invocation_context.invocation_id,
        author='user',
        content=new_message,
    )
    self.session_service.append_event(session=session, event=event)

  async def run_live(
      self,
      *,
      session: Session,
      live_request_queue: LiveRequestQueue,
      run_config: RunConfig = RunConfig(),
  ) -> AsyncGenerator[Event, None]:
    """Runs the agent in live mode (experimental feature).

    Args:
        session: The session to use.
        live_request_queue: The queue for live requests.
        run_config: The run config for the agent.

    Yields:
        The events generated by the agent.

    .. warning::
        This feature is **experimental** and its API or behavior may change
        in future releases.
    """
    # TODO: right now, only works for a single audio agent without FC.
    invocation_context = self._new_invocation_context_for_live(
        session,
        live_request_queue=live_request_queue,
        run_config=run_config,
    )

    root_agent = self.agent
    invocation_context.agent = self._find_agent_to_run(session, root_agent)

    invocation_context.active_streaming_tools = {}
    # TODO(hangfei): switch to use canonical_tools.
    for tool in invocation_context.agent.tools:
      # replicate a LiveRequestQueue for streaming tools that relis on
      # LiveRequestQueue
      from typing import get_type_hints

      type_hints = get_type_hints(tool)
      for arg_type in type_hints.values():
        if arg_type is LiveRequestQueue:
          if not invocation_context.active_streaming_tools:
            invocation_context.active_streaming_tools = {}
          active_streaming_tools = ActiveStreamingTool(
              stream=LiveRequestQueue()
          )
          invocation_context.active_streaming_tools[tool.__name__] = (
              active_streaming_tools
          )

    async for event in invocation_context.agent.run_live(invocation_context):
      self.session_service.append_event(session=session, event=event)
      yield event

  async def close_session(self, session: Session):
    """Closes a session and adds it to the memory service (experimental feature).

    Args:
        session: The session to close.
    """
    if self.memory_service:
      await self.memory_service.add_session_to_memory(session)
    self.session_service.close_session(session=session)

  def _find_agent_to_run(
      self, session: Session, root_agent: BaseAgent
  ) -> BaseAgent:
    """Finds the agent to run to continue the session.

    A qualified agent must be either of:
    - The root agent;
    - An LlmAgent who replied last and is capable to transfer to any other agent
      in the agent hierarchy.

    Args:
        session: The session to find the agent for.
        root_agent: The root agent of the runner.

    Returns:
      The agent of the last message in the session or the root agent.
    """
    for event in filter(lambda e: e.author != 'user', reversed(session.events)):
      if event.author == root_agent.name:
        # Found root agent.
        return root_agent
      if not (agent := root_agent.find_sub_agent(event.author)):
        # Agent not found, continue looking.
        logger.warning(
            'Event from an unknown agent: %s, event id: %s',
            event.author,
            event.id,
        )
        continue
      if self._is_transferable_across_agent_tree(agent):
        return agent
    # Falls back to root agent if no suitable agents are found in the session.
    return root_agent

  def _is_transferable_across_agent_tree(self, agent_to_run: BaseAgent) -> bool:
    """Whether the agent to run can transfer to any other agent in the agent tree.

    This typically means all agent_to_run's parent through root agent can
    transfer to their parent_agent.

    Args:
        agent_to_run: The agent to check for transferability.

    Returns:
        True if the agent can transfer, False otherwise.
    """
    agent = agent_to_run
    while agent:
      if not isinstance(agent, LlmAgent):
        # Only LLM-based Agent can provider agent transfer capability.
        return False
      if agent.disallow_transfer_to_parent:
        return False
      agent = agent.parent_agent
    return True

  def _new_invocation_context(
      self,
      session: Session,
      *,
      new_message: Optional[types.Content] = None,
      live_request_queue: Optional[LiveRequestQueue] = None,
      run_config: RunConfig = RunConfig(),
  ) -> InvocationContext:
    """Creates a new invocation context.

    Args:
        session: The session for the context.
        new_message: The new message for the context.
        live_request_queue: The live request queue for the context.
        run_config: The run config for the context.

    Returns:
        The new invocation context.
    """
    invocation_id = new_invocation_context_id()

    if run_config.support_cfc and isinstance(self.agent, LlmAgent):
      model_name = self.agent.canonical_model.model
      if not model_name.startswith('gemini-2'):
        raise ValueError(
            f'CFC is not supported for model: {model_name} in agent:'
            f' {self.agent.name}'
        )
      if built_in_code_execution not in self.agent.canonical_tools():
        self.agent.tools.append(built_in_code_execution)

    return InvocationContext(
        artifact_service=self.artifact_service,
        session_service=self.session_service,
        memory_service=self.memory_service,
        invocation_id=invocation_id,
        agent=self.agent,
        session=session,
        user_content=new_message,
        live_request_queue=live_request_queue,
        run_config=run_config,
    )

  def _new_invocation_context_for_live(
      self,
      session: Session,
      *,
      live_request_queue: Optional[LiveRequestQueue] = None,
      run_config: RunConfig = RunConfig(),
  ) -> InvocationContext:
    """Creates a new invocation context for live multi-agent."""

    # For live multi-agent, we need model's text transcription as context for
    # next agent.
    if self.agent.sub_agents and live_request_queue:
      if not run_config.response_modalities:
        # default
        run_config.response_modalities = ['AUDIO']
        if not run_config.output_audio_transcription:
          run_config.output_audio_transcription = (
              types.AudioTranscriptionConfig()
          )
      elif 'TEXT' not in run_config.response_modalities:
        if not run_config.output_audio_transcription:
          run_config.output_audio_transcription = (
              types.AudioTranscriptionConfig()
          )
    return self._new_invocation_context(
        session,
        live_request_queue=live_request_queue,
        run_config=run_config,
    )


class InMemoryRunner(Runner):
  """An in-memory Runner for testing and development.

  This runner uses in-memory implementations for artifact, session, and memory
  services, providing a lightweight and self-contained environment for agent
  execution.

  Attributes:
      agent: The root agent to run.
      app_name: The application name of the runner. Defaults to
        'InMemoryRunner'.
  """

  def __init__(self, agent: LlmAgent, *, app_name: str = 'InMemoryRunner'):
    """Initializes the InMemoryRunner.

    Args:
        agent: The root agent to run.
        app_name: The application name of the runner. Defaults to
          'InMemoryRunner'.
    """
    super().__init__(
        app_name=app_name,
        agent=agent,
        artifact_service=InMemoryArtifactService(),
        session_service=InMemorySessionService(),
        memory_service=InMemoryMemoryService(),
    )