Record a failure when the selection yields no export rows 🟥

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/orchestration/test_scenario_export_orchestrator.py

@@ -11,6 +11,7 @@ from moto import mock_aws
 from openpyxl import load_workbook
 
 from domain.scenario_export.scenario_sheet import ExportMeasure, PropertyScenarioData
+from domain.tasks.subtasks import SubTaskFailure
 from infrastructure.s3.s3_client import S3Client
 from orchestration.scenario_export_orchestrator import ScenarioExportOrchestrator
 from tests.infrastructure import make_boto_client
@@ -155,3 +156,29 @@ def test_an_email_failure_does_not_lose_the_built_export(exports: S3Client) -> N
     # on sub_task.outputs, so the link isn't lost).
     assert result.presigned_url
     assert exports.get_object(result.export_s3_key)
+
+
+def test_a_selection_that_yields_no_rows_is_a_recorded_failure(
+    exports: S3Client,
+) -> None:
+    # arrange — no property has a default Plan under the scenario (model A), so
+    # the repo returns no rows for it.
+    email = _RecordingEmail()
+    orchestrator = ScenarioExportOrchestrator(
+        rows=_FakeRows({}),
+        scenarios=_FakeScenarioNames({5: "Fabric first"}),
+        exports=exports,
+        email=email,
+        url_ttl_seconds=3600,
+    )
+
+    # act / assert — a recorded failure, never an empty workbook emailed.
+    with pytest.raises(SubTaskFailure):
+        orchestrator.run(
+            portfolio_id=100,
+            scenario_ids=[5],
+            property_ids=[1],
+            recipient_email="user@example.com",
+            export_name="portfolio-100",
+        )
+    assert email.sent == []