fix(workflow): Preserve explicit single-turn contents

[spectaclehong]

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Link to Issue or Description of Change

1. Link to an existing issue (if applicable):

• Closes: single_turn workflow nodes overwrite explicit include_contents #6046

Problem:

single_turn LlmAgent workflow nodes currently force include_contents to none at runtime, even when the user explicitly configures include_contents="default". That silently changes the agent configuration and prevents one-shot workflow nodes from intentionally receiving relevant session or workflow history.

Solution:

Only apply the workflow single_turn default of include_contents="none" when include_contents was not explicitly set by the user. This preserves the existing implicit default behavior while respecting explicit include_contents="default" and include_contents="none" values.

Regression coverage was added for implicit and explicit include_contents cases.

Testing Plan

Unit Tests:

• I have added or updated unit tests for my change.
• All unit tests pass locally.

Targeted workflow tests pass locally:

uv run pytest tests/unittests/workflow/test_llm_agent_as_node.py -q

Result:

28 passed, 8 skipped, 4 xfailed

Python 3.10 tox unit suite passes locally:

uv tool run --from tox --with tox-uv tox -e py310

Result:

7044 passed, 21 skipped, 31 xfailed, 9 xpassed

Pre-commit hooks pass for changed files:

uv run pre-commit run --files src/google/adk/workflow/_llm_agent_wrapper.py tests/unittests/workflow/test_llm_agent_as_node.py

Manual End-to-End (E2E) Tests:

Validated manually with a local workflow application that uses a single_turn workflow LlmAgent configured with include_contents="default". The run confirmed that the explicit contents mode is preserved instead of being overwritten to none.

No ADK Web or UI behavior is changed.

Checklist

• I have read the CONTRIBUTING.md document.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have added tests that prove my fix is effective or that my feature works.
• New and existing unit tests pass locally with my changes.
• I have manually tested my changes end-to-end.
• Any dependent changes have been merged and published in downstream modules.

Additional context

No documentation update was made because this change does not add a new user-facing API or guide behavior; it preserves explicit configuration that was already supported by LlmAgent.include_contents.

No dependent changes are required.

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[adk-bot]

Response from ADK Triaging Agent

Hello @spectaclehong, thank you for your contribution!

We noticed that a couple of things are missing according to our contribution guidelines:

1. Contributor License Agreement (CLA): It looks like the CLA check has failed. Please visit https://cla.developers.google.com/ to sign the Google CLA so that we can review your pull request.
2. Testing Summary: Although you've included the test commands in the "Tests" section, could you please provide a brief summary of the passed pytest results? This helps our reviewers ensure everything is working as expected.

This information will help reviewers to review your PR more efficiently. Thanks!