diff --git a/tests/integration/codex-chat-reasoning-http-e2e.test.ts b/tests/integration/codex-chat-reasoning-http-e2e.test.ts
index 02b9fc9aae8..e5a03749ff7 100644
--- a/tests/integration/codex-chat-reasoning-http-e2e.test.ts
+++ b/tests/integration/codex-chat-reasoning-http-e2e.test.ts
@@ -179,8 +179,9 @@ async function startRouteServer() {
       });
       await bridgeRouteResponse(await chatRoute.POST(request), outgoing);
     } catch (error) {
+      // Mock route bridge: surface the message, never the raw stack (js/stack-trace-exposure).
       outgoing.writeHead(500, { "content-type": "text/plain" });
-      outgoing.end(error instanceof Error ? error.stack : String(error));
+      outgoing.end(error instanceof Error ? error.message : String(error));
     }
   });