feat(evals): add ground_truth support for similarity evaluator

- Include expected_output as ground_truth in Foundry JSONL dataset rows
- Add ground_truth to item schema and data mapping for similarity evaluator
- Add expected_output parameter to evaluate_workflow
- Add similarity Pattern 3 to evaluate_agent and evaluate_workflow samples
- Add tests for ground_truth in dataset, schema, and evaluate_workflow

python/packages/core/agent_framework/_evaluation.py

@@ -1659,6 +1659,7 @@ async def evaluate_workflow(
     workflow: Workflow,
     workflow_result: WorkflowRunResult | None = None,
     queries: str | Sequence[str] | None = None,
+    expected_output: str | Sequence[str] | None = None,
     evaluators: Evaluator | Callable[..., Any] | Sequence[Evaluator | Callable[..., Any]],
     eval_name: str | None = None,
     include_overall: bool = True,
@@ -1683,6 +1684,11 @@ async def evaluate_workflow(
         workflow: The workflow instance.
         workflow_result: A completed ``WorkflowRunResult``.
         queries: Test queries to run through the workflow.
+        expected_output: Ground-truth expected output(s), one per query. A
+            single string is wrapped into a one-element list. When provided,
+            must be the same length as ``queries``. Each value is stamped on
+            the corresponding ``EvalItem.expected_output`` for evaluators
+            that compare against a reference answer (e.g. similarity).
         evaluators: One or more ``Evaluator`` instances.
         eval_name: Display name for the evaluation.
         include_overall: Whether to evaluate the workflow's final output.
@@ -1720,10 +1726,15 @@ async def evaluate_workflow(
     # Normalize singular query to list
     if isinstance(queries, str):
         queries = [queries]
+    if isinstance(expected_output, str):
+        expected_output = [expected_output]
 
     if workflow_result is None and queries is None:
         raise ValueError("Provide either 'workflow_result' or 'queries'.")
 
+    if expected_output is not None and queries is not None and len(expected_output) != len(queries):
+        raise ValueError(f"Got {len(queries)} queries but {len(expected_output)} expected_output values.")
+
     if num_repetitions < 1:
         raise ValueError(f"num_repetitions must be >= 1, got {num_repetitions}.")
 
@@ -1737,7 +1748,7 @@ async def evaluate_workflow(
     if queries is not None:
         results_list: list[WRR] = []
         for _rep in range(num_repetitions):
-            for q in queries:
+            for qi, q in enumerate(queries):
                 result = await workflow.run(q)
                 if not isinstance(result, WRR):
                     raise TypeError(f"Expected WorkflowRunResult from workflow.run(), got {type(result).__name__}.")
@@ -1746,6 +1757,8 @@ async def evaluate_workflow(
                 if include_overall:
                     overall_item = _build_overall_item(q, result)
                     if overall_item:
+                        if expected_output is not None:
+                            overall_item.expected_output = expected_output[qi]
                         overall_items.append(overall_item)
     else:
         assert workflow_result is not None  # noqa: S101  # nosec B101