fix #2404: branching and include_contents='none'

[ananyablonko]

Consider code where a sub_agent somewhere under a ParallelAgent has include_contents='none'.

import asyncio
import os
from typing import TypedDict
from dotenv import load_dotenv

from google.adk.agents import LlmAgent, ParallelAgent, SequentialAgent
from google.adk.runners import Runner
from google.adk.sessions import DatabaseSessionService, InMemorySessionService
from google.genai import types
import logging

USE_DB=False

load_dotenv()
logging.basicConfig(
    filename='log.log',
    level=logging.DEBUG
)
for logger_name in ["httpcore"]:
    logging.getLogger(logger_name).setLevel(logging.ERROR)

class AgentArgs(TypedDict):
    model: str
    instruction: str

class SessionArgs(TypedDict):
    user_id: str
    session_id: str

agent_args = AgentArgs(
    model="gemini-2.0-flash",
    instruction="Answer 'Ack' and nothing else."
)

session_args = SessionArgs(
    user_id="0",
    session_id="0"
)

app_name = "Test"

def create_agent_in_branch(i: int):
    agent_1 = LlmAgent(
        name=f"subagent_{i}_1",
        **agent_args
    )

    agent_2 = LlmAgent(
        name=f"subagent_{i}_2",
        include_contents='none',
        **agent_args
    )

    return SequentialAgent(
        name=f"agent_{i}",
        sub_agents=[agent_1, agent_2]
    )



root = ParallelAgent(
    name="root",
    sub_agents=[create_agent_in_branch(i) for i in range(1, 5)]
)

runner = Runner(
    agent=root,
    app_name=app_name,
    session_service=DatabaseSessionService(db_url=os.getenv("DB_URL", "")) if USE_DB else InMemorySessionService(),
)


async def main() -> None:
    try:
        await runner.session_service.delete_session(app_name=app_name, **session_args)
    except:
        pass
    await runner.session_service.create_session(app_name=app_name, **session_args)

    message = types.Content(role="user", parts=[types.Part(text=" ")])
    async for event in runner.run_async(**session_args, new_message=message):
        if event.is_final_response():
            print(((event.content or types.Content()).parts or [types.Part()])[0].text or "")


if __name__ == '__main__':
    asyncio.run(main())

The log here will often have one or more subagent_{i}_2 not receive their prompts from subagent_{i}_1.
This inconsistency is caused by the way include_contents='none' is implemented in flows/llm_flows/contents.py:328-356:

    for i in range(len(events) - 1, -1, -1):
    event = events[i]
    if event.author == 'user' or _is_other_agent_reply(agent_name, event):
      return _get_contents(current_branch, events[i:], agent_name)

  return []

That is, we first find the most recent (other-agent / user) event, even if it's not on our branch, and then filter the remainder. Thus in the above example, we may sometimes filter out all events, when we expect to have the event of a previous agent in a SequentialAgent.

The solution is to first filter events by branch, and only then search for the latest.

TEST SUMMARY:

=================================================== short test summary info =================================================== 
FAILED tests/unittests/agents/test_agent_config.py::test_agent_config_discriminator_with_sub_agents[GOOGLE_AI-LoopAgent-LoopAgent] - FileNotFoundError: Config file not found: C:\Users\AnanYablonko\AppData\Local\Temp\pytest-of-AnanYablonko\pytest-1\test_age...
FAILED tests/unittests/agents/test_agent_config.py::test_agent_config_discriminator_with_sub_agents[GOOGLE_AI-google.adk.agents.LoopAgent-LoopAgent] - FileNotFoundError: Config file not found: C:\Users\AnanYablonko\AppData\Local\Temp\pytest-of-AnanYablonko\pytest-1\test_age...
FAILED tests/unittests/agents/test_agent_config.py::test_agent_config_discriminator_with_sub_agents[GOOGLE_AI-google.adk.agents.loop_agent.LoopAgent-LoopAgent] - FileNotFoundError: Config file not found: C:\Users\AnanYablonko\AppData\Local\Temp\pytest-of-AnanYablonko\pytest-1\test_age...
FAILED tests/unittests/agents/test_agent_config.py::test_agent_config_discriminator_with_sub_agents[GOOGLE_AI-ParallelAgent-ParallelAgent] - FileNotFoundError: Config file not found: C:\Users\AnanYablonko\AppData\Local\Temp\pytest-of-AnanYablonko\pytest-1\test_age...
FAILED tests/unittests/agents/test_agent_config.py::test_agent_config_discriminator_with_sub_agents[GOOGLE_AI-google.adk.agents.ParallelAgent-ParallelAgent] - FileNotFoundError: Config file not found: C:\Users\AnanYablonko\AppData\Local\Temp\pytest-of-AnanYablonko\pytest-1\test_age...
FAILED tests/unittests/agents/test_agent_config.py::test_agent_config_discriminator_with_sub_agents[GOOGLE_AI-google.adk.agents.parallel_agent.ParallelAgent-ParallelAgent] - FileNotFoundError: Config file not found: C:\Users\AnanYablonko\AppData\Local\Temp\pytest-of-AnanYablonko\pytest-1\test_age...
FAILED tests/unittests/agents/test_agent_config.py::test_agent_config_discriminator_with_sub_agents[GOOGLE_AI-SequentialAgent-SequentialAgent] - FileNotFoundError: Config file not found: C:\Users\AnanYablonko\AppData\Local\Temp\pytest-of-AnanYablonko\pytest-1\test_age...
FAILED tests/unittests/agents/test_agent_config.py::test_agent_config_discriminator_with_sub_agents[GOOGLE_AI-google.adk.agents.SequentialAgent-SequentialAgent] - FileNotFoundError: Config file not found: C:\Users\AnanYablonko\AppData\Local\Temp\pytest-of-AnanYablonko\pytest-1\test_age...
FAILED tests/unittests/agents/test_agent_config.py::test_agent_config_discriminator_with_sub_agents[GOOGLE_AI-google.adk.agents.sequential_agent.SequentialAgent-SequentialAgent] - FileNotFoundError: Config file not found: C:\Users\AnanYablonko\AppData\Local\Temp\pytest-of-AnanYablonko\pytest-1\test_age...
FAILED tests/unittests/agents/test_agent_config.py::test_agent_config_discriminator_with_sub_agents[VERTEX-LoopAgent-LoopAgent] - FileNotFoundError: Config file not found: C:\Users\AnanYablonko\AppData\Local\Temp\pytest-of-AnanYablonko\pytest-1\test_age...
FAILED tests/unittests/agents/test_agent_config.py::test_agent_config_discriminator_with_sub_agents[VERTEX-google.adk.agents.LoopAgent-LoopAgent] - FileNotFoundError: Config file not found: C:\Users\AnanYablonko\AppData\Local\Temp\pytest-of-AnanYablonko\pytest-1\test_age...
FAILED tests/unittests/agents/test_agent_config.py::test_agent_config_discriminator_with_sub_agents[VERTEX-google.adk.agents.loop_agent.LoopAgent-LoopAgent] - FileNotFoundError: Config file not found: C:\Users\AnanYablonko\AppData\Local\Temp\pytest-of-AnanYablonko\pytest-1\test_age...
FAILED tests/unittests/agents/test_agent_config.py::test_agent_config_discriminator_with_sub_agents[VERTEX-ParallelAgent-ParallelAgent] - FileNotFoundError: Config file not found: C:\Users\AnanYablonko\AppData\Local\Temp\pytest-of-AnanYablonko\pytest-1\test_age...
FAILED tests/unittests/agents/test_agent_config.py::test_agent_config_discriminator_with_sub_agents[VERTEX-google.adk.agents.ParallelAgent-ParallelAgent] - FileNotFoundError: Config file not found: C:\Users\AnanYablonko\AppData\Local\Temp\pytest-of-AnanYablonko\pytest-1\test_age...
FAILED tests/unittests/agents/test_agent_config.py::test_agent_config_discriminator_with_sub_agents[VERTEX-google.adk.agents.parallel_agent.ParallelAgent-ParallelAgent] - FileNotFoundError: Config file not found: C:\Users\AnanYablonko\AppData\Local\Temp\pytest-of-AnanYablonko\pytest-1\test_age...
FAILED tests/unittests/agents/test_agent_config.py::test_agent_config_discriminator_with_sub_agents[VERTEX-SequentialAgent-SequentialAgent] - FileNotFoundError: Config file not found: C:\Users\AnanYablonko\AppData\Local\Temp\pytest-of-AnanYablonko\pytest-1\test_age...
FAILED tests/unittests/agents/test_agent_config.py::test_agent_config_discriminator_with_sub_agents[VERTEX-google.adk.agents.SequentialAgent-SequentialAgent] - FileNotFoundError: Config file not found: C:\Users\AnanYablonko\AppData\Local\Temp\pytest-of-AnanYablonko\pytest-1\test_age...
FAILED tests/unittests/agents/test_agent_config.py::test_agent_config_discriminator_with_sub_agents[VERTEX-google.adk.agents.sequential_agent.SequentialAgent-SequentialAgent] - FileNotFoundError: Config file not found: C:\Users\AnanYablonko\AppData\Local\Temp\pytest-of-AnanYablonko\pytest-1\test_age...
FAILED tests/unittests/agents/test_agent_config.py::test_agent_config_discriminator_llm_agent_with_sub_agents[GOOGLE_AI-LlmAgent-LlmAgent] - FileNotFoundError: Config file not found: C:\Users\AnanYablonko\AppData\Local\Temp\pytest-of-AnanYablonko\pytest-1\test_age...
FAILED tests/unittests/agents/test_agent_config.py::test_agent_config_discriminator_llm_agent_with_sub_agents[GOOGLE_AI-google.adk.agents.LlmAgent-LlmAgent] - FileNotFoundError: Config file not found: C:\Users\AnanYablonko\AppData\Local\Temp\pytest-of-AnanYablonko\pytest-1\test_age...
FAILED tests/unittests/agents/test_agent_config.py::test_agent_config_discriminator_llm_agent_with_sub_agents[GOOGLE_AI-google.adk.agents.llm_agent.LlmAgent-LlmAgent] - FileNotFoundError: Config file not found: C:\Users\AnanYablonko\AppData\Local\Temp\pytest-of-AnanYablonko\pytest-1\test_age...
FAILED tests/unittests/agents/test_agent_config.py::test_agent_config_discriminator_llm_agent_with_sub_agents[VERTEX-LlmAgent-LlmAgent] - FileNotFoundError: Config file not found: C:\Users\AnanYablonko\AppData\Local\Temp\pytest-of-AnanYablonko\pytest-1\test_age...
FAILED tests/unittests/agents/test_agent_config.py::test_agent_config_discriminator_llm_agent_with_sub_agents[VERTEX-google.adk.agents.LlmAgent-LlmAgent] - FileNotFoundError: Config file not found: C:\Users\AnanYablonko\AppData\Local\Temp\pytest-of-AnanYablonko\pytest-1\test_age...
FAILED tests/unittests/agents/test_agent_config.py::test_agent_config_discriminator_llm_agent_with_sub_agents[VERTEX-google.adk.agents.llm_agent.LlmAgent-LlmAgent] - FileNotFoundError: Config file not found: C:\Users\AnanYablonko\AppData\Local\Temp\pytest-of-AnanYablonko\pytest-1\test_age...
FAILED tests/unittests/cli/utils/test_cli_tools_click.py::test_cli_run_invokes_run_cli[GOOGLE_AI] - AssertionError: assert 1 == 0
FAILED tests/unittests/cli/utils/test_cli_tools_click.py::test_cli_run_invokes_run_cli[VERTEX] - AssertionError: assert 1 == 0  
FAILED tests/unittests/cli/utils/test_cli_tools_click.py::test_cli_eval_with_eval_set_file_path[GOOGLE_AI] - assert 0 == 1      
FAILED tests/unittests/cli/utils/test_cli_tools_click.py::test_cli_eval_with_eval_set_file_path[VERTEX] - assert 0 == 1
FAILED tests/unittests/evaluation/test_local_eval_sets_manager.py::TestLocalEvalSetsManager::test_local_eval_sets_manager_update_eval_case_eval_set_not_found[GOOGLE_AI] - OSError: [Errno 22] Invalid argument: '<tests.unittests.evaluation.test_local_eval_sets_manager.TestLocalEvalSetsManager ob...
FAILED tests/unittests/evaluation/test_local_eval_sets_manager.py::TestLocalEvalSetsManager::test_local_eval_sets_manager_update_eval_case_eval_set_not_found[VERTEX] - OSError: [Errno 22] Invalid argument: '<tests.unittests.evaluation.test_local_eval_sets_manager.TestLocalEvalSetsManager ob...
FAILED tests/unittests/evaluation/test_local_eval_sets_manager.py::TestLocalEvalSetsManager::test_local_eval_sets_manager_delete_eval_case_eval_set_not_found[GOOGLE_AI] - OSError: [Errno 22] Invalid argument: '<tests.unittests.evaluation.test_local_eval_sets_manager.TestLocalEvalSetsManager ob...
FAILED tests/unittests/evaluation/test_local_eval_sets_manager.py::TestLocalEvalSetsManager::test_local_eval_sets_manager_delete_eval_case_eval_set_not_found[VERTEX] - OSError: [Errno 22] Invalid argument: '<tests.unittests.evaluation.test_local_eval_sets_manager.TestLocalEvalSetsManager ob...
FAILED tests/unittests/sessions/test_session_service.py::test_get_session_with_config[GOOGLE_AI-SessionServiceType.DATABASE] - OSError: [Errno 22] Invalid argument
FAILED tests/unittests/sessions/test_session_service.py::test_get_session_with_config[VERTEX-SessionServiceType.DATABASE] - OSError: [Errno 22] Invalid argument
================================= 34 failed, 4540 passed, 3044 warnings in 187.68s (0:03:07) ==================================

[gemini-code-assist]

Summary of Changes

Hello @ananyablonko, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request resolves a critical bug affecting agents configured with include_contents='none' when operating within branched conversational structures. Previously, the event filtering logic could incorrectly pull context from unrelated branches, leading to agents failing to receive necessary prompts. The changes introduce a more precise event filtering mechanism that prioritizes the agent's current branch, ensuring that conversational context is accurately maintained and agents behave as expected in complex, multi-threaded interactions.

Highlights

• Fix for include_contents='none' in branched agents: Addressed a bug where agents configured with include_contents='none' within a branched conversation structure (e.g., ParallelAgent with SequentialAgent sub-agents) were not consistently receiving their expected prompts. The issue stemmed from the event filtering logic incorrectly identifying the 'most recent other-agent/user event' across all branches, rather than strictly within the agent's specific branch.
• Refactored event filtering logic: The event processing mechanism has been refactored to first filter events by the agent's current branch before determining the latest relevant event. This ensures accurate context retrieval and reliable agent behavior in complex, multi-branched conversational flows, particularly when include_contents='none' is used.
• Added new test case for multi-branch scenarios: A new test, test_include_contents_none_multi_branch_current_turn, has been introduced to validate the corrected behavior of include_contents='none' in multi-branch agent setups. This test specifically simulates a ParallelAgent scenario to confirm that sub-agents correctly receive context from their own branch.

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[gemini-code-assist]

Code Review

This pull request addresses a bug related to context inclusion for agents with include_contents='none' in multi-branch scenarios. The fix correctly ensures that events are filtered by branch before determining the current turn's starting point, preventing race conditions where an event from another branch could be incorrectly selected. The change introduces a new helper function, _should_include_event_in_context, to centralize event filtering logic, which improves code clarity. A corresponding unit test has been added to validate the fix in a multi-branch environment. My feedback focuses on further improving the readability and documentation of the new helper function.