diff --git a/agent.py b/agent.py
index 3e21e53..ce0f859 100644
--- a/agent.py
+++ b/agent.py
@@ -764,7 +764,7 @@ class ProductionIncidentCommander(A2AAgent[CommanderConfig, NoAuth]):
         if approval_acknowledgement != APPROVAL_ACK:
             result = ExecutionResult(incident_id=incident_id, status="denied", dry_run=dry_run, approval_provenance={"accepted": False, "reason": "approval acknowledgement mismatch"}, step_results=[], final_incident_state="unchanged", artifact_paths=[f"outputs/incidents/{incident_id}/execution.json"])
             await workspace_write_json(ctx, f"outputs/incidents/{incident_id}/execution.json", result)
-            return result
+            return result.model_dump(mode="json")
         clean = validate_incident_path(plan_path, incident_id, must_exist_under_incident=True)
         text = await workspace_read_text(ctx, clean)
         plan = RemediationPlan.model_validate_json(text)