diff --git a/ui/src/ui/realtime-talk-consult.test.ts b/ui/src/ui/realtime-talk-consult.test.ts
index 90ba553b2ff..c360530ac25 100644
--- a/ui/src/ui/realtime-talk-consult.test.ts
+++ b/ui/src/ui/realtime-talk-consult.test.ts
@@ -3,6 +3,14 @@
 import { describe, expect, it, vi } from "vitest";
 import { submitRealtimeTalkConsult } from "./chat/realtime-talk-shared.js";
 
+function requireFirstMockCall(calls: readonly unknown[][], label: string): unknown[] {
+  const call = calls.at(0);
+  if (!call) {
+    throw new Error(`expected ${label} call`);
+  }
+  return call;
+}
+
 describe("RealtimeTalkSession consult handoff", () => {
   it("submits realtime consults through the Gateway tool-call endpoint", async () => {
     let listener: ((event: { event: string; payload?: unknown }) => void) | undefined;
@@ -41,7 +49,7 @@ describe("RealtimeTalkSession consult handoff", () => {
       submit,
     });
 
-    const toolCall = request.mock.calls[0] as
+    const toolCall = requireFirstMockCall(request.mock.calls, "Gateway request") as
       | [string, { sessionKey?: string; name?: string; args?: { question?: string } }]
       | undefined;
     expect(toolCall?.[0]).toBe("talk.client.toolCall");