From 5038c104563ce60bd5b326a410a183170e69191c Mon Sep 17 00:00:00 2001
From: Jason Dai <jsndai@google.com>
Date: Fri, 2 Oct 2026 12:25:08 -0700
Subject: [PATCH] fix: GenAI Client(evals) - Default missing rubric verdicts to
 False

PiperOrigin-RevId: 992471781
---
 agentplatform/_genai/types/evals.py          |  2 +-
 tests/unit/agentplatform/genai/test_evals.py | 44 ++++++++++++++++++++
 vertexai/_genai/types/evals.py               |  2 +-
 3 files changed, 46 insertions(+), 2 deletions(-)

diff --git a/agentplatform/_genai/types/evals.py b/agentplatform/_genai/types/evals.py
index b50253ce6c..23c2a22d78 100644
--- a/agentplatform/_genai/types/evals.py
+++ b/agentplatform/_genai/types/evals.py
@@ -948,7 +948,7 @@ class RubricVerdict(_common.BaseModel):
       generated.""",
     )
     verdict: Optional[bool] = Field(
-        default=None,
+        default=False,
         description="""Required. Outcome of the evaluation against the rubric, represented as a
       boolean. `true` indicates a "Pass", `false` indicates a "Fail".""",
     )
diff --git a/tests/unit/agentplatform/genai/test_evals.py b/tests/unit/agentplatform/genai/test_evals.py
index 492d9cb429..98ea91ba0a 100644
--- a/tests/unit/agentplatform/genai/test_evals.py
+++ b/tests/unit/agentplatform/genai/test_evals.py
@@ -45,6 +45,7 @@
     types as agentplatform_genai_types,
 )
 from agentplatform._genai.types import common as common_types
+from vertexai._genai import evals as vertexai_evals
 from google.genai import client
 from google.genai import errors as genai_errors
 from google.genai import types as genai_types
@@ -2311,6 +2312,49 @@ def test_eval_evaluate_with_agent_info(self, mock_execute_evaluation):
         assert kwargs["agent_info"] == agent_info
 
 
+class TestRubricVerdict:
+    """Unit tests for parsing RubricVerdict from API responses."""
+
+    @pytest.mark.parametrize(
+        "evals_module", [evals, vertexai_evals], ids=["agent_platform", "vertexai"]
+    )
+    def test_evaluate_instances_missing_verdict_is_false(self, evals_module):
+        api_client = mock.MagicMock()
+        api_client.vertexai = True
+        api_client.request.return_value.body = json.dumps(
+            {
+                "metricResults": [
+                    {
+                        "score": 0.5,
+                        "rubricVerdicts": [
+                            {
+                                "evaluatedRubric": {
+                                    "content": {
+                                        "property": {"description": "In English."}
+                                    }
+                                },
+                                "verdict": True,
+                            },
+                            {
+                                "evaluatedRubric": {
+                                    "content": {
+                                        "property": {"description": "One sentence."}
+                                    }
+                                },
+                                "reasoning": "The response has two sentences.",
+                            },
+                        ],
+                    }
+                ]
+            }
+        )
+
+        response = evals_module.Evals(api_client_=api_client)._evaluate_instances()
+
+        verdicts = response.metric_results[0].rubric_verdicts
+        assert [verdict.verdict for verdict in verdicts] == [True, False]
+
+
 class TestEvalsVisualization:
     # fmt: off
     @mock.patch(
diff --git a/vertexai/_genai/types/evals.py b/vertexai/_genai/types/evals.py
index 080e46f5ec..4e90bb05ad 100644
--- a/vertexai/_genai/types/evals.py
+++ b/vertexai/_genai/types/evals.py
@@ -948,7 +948,7 @@ class RubricVerdict(_common.BaseModel):
       generated.""",
     )
     verdict: Optional[bool] = Field(
-        default=None,
+        default=False,
         description="""Required. Outcome of the evaluation against the rubric, represented as a
       boolean. `true` indicates a "Pass", `false` indicates a "Fail".""",
     )