fix(eval): handle unevaluated final response v2 results

[pragnyanramtha]

Summary

Fixes a small aggregation edge case in FinalResponseMatchV2Evaluator: when every per-invocation result is skipped or not evaluated, the evaluator currently divides by zero while computing the overall score.

Root Cause

aggregate_invocation_results() filters out results whose score is None or whose eval_status is NOT_EVALUATED, but it unconditionally computes:

overall_score = num_valid / num_evaluated

If all judge samples fail to produce a usable score, num_evaluated remains 0 and evaluation crashes instead of returning a not-evaluated aggregate result. Other ADK evaluators handle this condition by returning overall_score=None and overall_eval_status=NOT_EVALUATED.

Change

• Return an EvaluationResult with overall_score=None and overall_eval_status=NOT_EVALUATED when no FinalResponseMatchV2 invocation results are evaluable.
• Add a focused regression test for all-skipped/all-not-evaluated invocation results.

Validation

uv sync --extra test
uv run pytest tests/unittests/evaluation/test_final_response_match_v2.py

Result: 18 passed, 20 warnings.

Full unit suite was not run; this patch is limited to FinalResponseMatchV2 aggregation and its targeted unit test file.

[pragnyanramtha]

Refreshed this branch with current main in f61da061.

Validation rerun:

• uv run --extra test pytest tests/unittests/evaluation/test_final_response_match_v2.py -q (18 passed)
• uv run --extra dev pyink --check src/google/adk/evaluation/final_response_match_v2.py tests/unittests/evaluation/test_final_response_match_v2.py
• git diff --check

[pragnyanramtha]

Refreshed this branch with current main in f7a83e9b.

Validation rerun:

• uv run --extra test pytest tests/unittests/evaluation/test_final_response_match_v2.py -q (18 passed, 20 experimental warnings)
• uv run --extra dev pyink --check src/google/adk/evaluation/final_response_match_v2.py tests/unittests/evaluation/test_final_response_match_v2.py
• uv run --extra dev isort --check-only src/google/adk/evaluation/final_response_match_v2.py tests/unittests/evaluation/test_final_response_match_v2.py
• git diff --check

[pragnyanramtha]

Pushed 430f312d to address the failing CI pre-commit job.

The failure was from repository-wide hooks updating existing files outside this PR's evaluator patch:

• add newline at EOF for src/google/adk/cli/browser/assets/config/runtime-config.json
• apply pyink formatting to tests/unittests/cli/utils/test_gcp_utils.py

Validation:

• uv run --extra dev pre-commit run --all-files -> passed
• uv run --extra test pytest tests/unittests/evaluation/test_final_response_match_v2.py -q -> 18 passed, 20 experimental warnings
• git diff --check -> passed

[rohityan]

Hi @pragnyanramtha , Thank you for your contribution! We appreciate you taking the time to submit this pull request. Your PR has been received by the team and is currently under review. We will provide feedback as soon as we have an update to share.

[rohityan]

Hi @sasha-gitg , can you please review this.

[pragnyanramtha]

I noticed the request clarification label is still on this PR, but I do not see a specific clarification request in the thread. The branch is current and all checks are green after 430f312d; happy to clarify or adjust anything if there is a maintainer question I missed.