Record a failure when the selection yields no export rows 🟩

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

orchestration/scenario_export_orchestrator.py

@@ -91,6 +91,18 @@ class ScenarioExportOrchestrator:
             named_sheets.append((self._scenarios.name_for(scenario_id), sheet))
             row_count += len(sheet.rows)
 
+        if row_count == 0:
+            # No Property had a default Plan under any requested Scenario (model
+            # A) — a recorded failure, never an empty workbook emailed (ADR-0065).
+            raise SubTaskFailure(
+                "the scenario export selection produced no exportable rows",
+                details={
+                    "portfolio_id": portfolio_id,
+                    "scenario_ids": list(scenario_ids),
+                    "property_count": len(property_ids),
+                },
+            )
+
         data = render_workbook(named_sheets)
         key = f"{self._key_prefix}/{export_name}.xlsx"
         self._exports.put_object(key, data)