fix(runners): Preserve state_delta in NodeRunner path

[trongthanht3]

Please ensure you have read the contribution guide before creating a pull request.

Link to Issue or Description of Change

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

• Closes: state_delta passed to /run endpoint is silently ignored in Workflow (NodeRunner) path #5763

Problem:
/run and /run_sse already pass state_delta into Runner.run_async, but the ADK 2.0 NodeRunner execution path was not attaching that delta to the initial user event. As a result, workflow nodes and root LlmAgent executions could not see the requested state before running.

Solution:
Thread state_delta through the NodeRunner path and persist non-empty deltas on the initial user event via EventActions, matching the legacy runner behavior while preserving existing user-event isolation-scope handling.

Testing Plan

Unit Tests:

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

Passed results:

pre-commit run --files src/google/adk/runners.py tests/unittests/runners/test_runner_state_delta.py
Passed

uv run pytest tests/unittests/runners/test_runner_state_delta.py tests/unittests/runners/test_runner_node.py
33 passed

uv run pytest tests/unittests
6622 passed, 18 skipped, 31 xfailed, 9 xpassed

tox
py310: OK
py311: OK
py312: OK
py313: OK
py314: OK

Manual End-to-End (E2E) Tests:

Ran adk web with an agent callback that logs session state before execution:

uv run adk web \
  --host 127.0.0.1 \
  --port 8765 \
  --session_service_uri memory:// \
  --artifact_service_uri memory:// \
  --no-reload \
  /tmp/adk_state_delta_e2e

Sent /run and /run_sse requests with:

{
  "app_name": "state_delta_app",
  "user_id": "e2e-user",
  "session_id": "e2e-session",
  "new_message": {
    "role": "user",
    "parts": [
      {
        "text": "hello"
      }
    ]
  },
  "state_delta": {
    "test_state": "must_change"
  }
}

Observed:

/run callback log:
STATE_DELTA_E2E test_state=must_change

/run session state:
"state":{"test_state":"must_change"}

/run user event:
"actions":{"stateDelta":{"test_state":"must_change"}}

/run_sse callback log:
STATE_DELTA_E2E test_state=must_change_sse

/run_sse session state:
"state":{"test_state":"must_change_sse"}

/run_sse user event:
"actions":{"stateDelta":{"test_state":"must_change_sse"}}

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 dependent changes are required.

[DeanChensj]

@gemini-cli /review

[github-actions]

🤖 Hi @DeanChensj, I've received your request, and I'm working on it now! You can track my progress in the logs for more details.

[github-actions]

The changes look solid and correctly address the issue where state_delta was not being attached to the initial user event in the ADK 2.0 NodeRunner path. This ensures that session state updates requested via /run or /run_sse are visible to nodes and agents before they execute.

I've left one minor suggestion for code conciseness in runners.py, but overall this is a great fix with excellent test coverage. Approving!

[github-actions]

This is a good fix. It correctly threads state_delta through the NodeRunner path, ensuring the session state is updated before any nodes or agents execute.

One minor suggestion: this block could be slightly more concise, though the current version is perfectly clear.

    event = Event(
        invocation_id=ic.invocation_id,
        author='user',
        actions=EventActions(state_delta=state_delta) if state_delta else None,
        content=content,
    )

[github-actions]

Excellent test coverage. Verifying both BaseNode and LlmAgent callback scenarios ensures that the state delta is correctly applied in different execution paths.

[DeanChensj]

Could you move the tests to tests/unittests/runners/test_runner_node.py?

[trongthanht3]

I moved tests to tests/unittests/runners/test_runner_node.py as your request

[adk-bot]

Response from ADK Triaging Agent

Hello @trongthanht3, thank you for creating this PR!

Your PR description is very detailed, and we appreciate the thorough testing plan and logs! However, we noticed that the pre-commit CI check has failed.

To resolve any formatting or style issues, please ensure you run pre-commit locally across all files:

pre-commit run --all-files

You can refer to the Development Setup section of our contributing guidelines for details.

This will help us review and merge your changes more quickly. Thanks!