to_openeval()/from_openeval(): interop between EvalSet and the EvalPort portable format

[adhabnr-ux]

Hi maintainers,

ADK's own description is "building, evaluating, and deploying" agents, and google.adk.evaluation is already one of the most complete eval subsystems I've looked at across agent SDKs — so this seemed like a particularly good fit to raise.

I maintain EvalPort (https://github.com/adhabnr-ux/evalport), an open, provider-neutral JSON Schema spec for portable LLM eval test suites and result sets, meant as a common interchange format so eval data isn't locked to one framework. Spec: https://github.com/adhabnr-ux/evalport/blob/main/SPEC.md

Related precedent: openai/openai-python#3619 (openai/openai-python#3619 — open, not yet merged) is adding native to_openeval() / from_openeval() helpers onto that SDK's dataset/response types for the same reason.

Looking at src/google/adk/evaluation/eval_case.py and eval_set.py, an EvalSet.eval_cases is a list[EvalCase], each with a conversation: list[Invocation] where Invocation.user_content / final_response are genai_types.Content and intermediate_data carries tool calls. You already ship get_all_tool_calls() for pulling tool-call trajectories out of that, which makes a converter pretty direct:

# sketch, not a PR
def eval_case_to_openeval_testcase(case: EvalCase) -> dict:
    inv = case.conversation[0]  # simplest case: single-invocation, static conversation
    return {
        "id": case.eval_id,
        "input": inv.user_content.parts[0].text if inv.user_content.parts else "",
        "expected_output": (
            inv.final_response.parts[0].text
            if inv.final_response and inv.final_response.parts else None
        ),
        "expected_tools": [tc.name for tc in get_all_tool_calls(inv.intermediate_data)],
        "graders": ["exact_match"],  # or derived from case.rubrics
    }

which maps onto an EvalPort test case: https://github.com/adhabnr-ux/evalport/blob/main/spec/schemas/testcase.json

Since ADK already reads/writes eval sets as JSON via local_eval_sets_manager.py, this would mostly be a format bridge rather than new infrastructure — useful for anyone moving eval sets between ADK and other tooling. No pressure if this isn't a priority; happy to sketch a fuller PR if there's interest. (Per CONTRIBUTING.md, opening this as an issue first per your "large or complex changes" guidance.)

[adhabnr-ux]

Sounds good — no one else is working on this from my side, so it's all yours. Happy to review once you have a PR up, or answer any questions about the EvalPort TestCase/ResultSet schemas in the meantime.