diff --git a/src/agents/auth-profiles/external-oauth.test.ts b/src/agents/auth-profiles/external-oauth.test.ts
index 9d6bd180c4f0..26e63d9d3133 100644
--- a/src/agents/auth-profiles/external-oauth.test.ts
+++ b/src/agents/auth-profiles/external-oauth.test.ts
@@ -96,7 +96,7 @@ describe("auth external oauth helpers", () => {
     });
 
     const resolveParams = requireRecord(
-      resolveExternalAuthProfilesWithPluginsMock.mock.calls[0]?.[0],
+      resolveExternalAuthProfilesWithPluginsMock.mock.calls.at(0)?.[0],
       "resolve external auth params",
     );
     expect(resolveParams.config).toBe(cfg);
diff --git a/src/agents/auth-profiles/state-observation.test.ts b/src/agents/auth-profiles/state-observation.test.ts
index 1fbc6abb5ab0..c7c76ae1d3a1 100644
--- a/src/agents/auth-profiles/state-observation.test.ts
+++ b/src/agents/auth-profiles/state-observation.test.ts
@@ -29,7 +29,7 @@ describe("logAuthProfileFailureStateChange", () => {
       now: 1_700_000_000_000,
     });
 
-    const consoleLine = warnSpy.mock.calls[0]?.[0];
+    const consoleLine = warnSpy.mock.calls.at(0)?.[0];
     expect(typeof consoleLine).toBe("string");
     expect(consoleLine).toContain("runId=run-1 forged entry test");
     expect(consoleLine).toContain("provider=openai]8;;https://evil.test");
diff --git a/src/agents/auth-profiles/usage.test.ts b/src/agents/auth-profiles/usage.test.ts
index 05753d47b147..7e402a56885c 100644
--- a/src/agents/auth-profiles/usage.test.ts
+++ b/src/agents/auth-profiles/usage.test.ts
@@ -876,7 +876,7 @@ describe("markAuthProfileFailure — WHAM-aware Codex cooldowns", () => {
     await markCodexFailureAt({ store, now });
 
     expect(fetchMock).toHaveBeenCalledTimes(1);
-    const [url, init] = fetchMock.mock.calls[0] as [string, RequestInit];
+    const [url, init] = fetchMock.mock.calls.at(0) as [string, RequestInit];
     expect(url).toBe("https://chatgpt.com/backend-api/wham/usage");
     expect(init.method).toBe("GET");
     const headers = init.headers as Record<string, string>;
diff --git a/src/agents/bash-tools.exec.path.test.ts b/src/agents/bash-tools.exec.path.test.ts
index 456b80f15371..1136f6001e73 100644
--- a/src/agents/bash-tools.exec.path.test.ts
+++ b/src/agents/bash-tools.exec.path.test.ts
@@ -250,7 +250,7 @@ describe("exec PATH login shell merge", () => {
 
       expect(entries).toEqual(["/usr/bin"]);
       expect(shellPathMock).toHaveBeenCalledTimes(1);
-      const shellPathCall = shellPathMock.mock.calls[0]?.[0];
+      const shellPathCall = shellPathMock.mock.calls.at(0)?.[0];
       expect(shellPathCall?.env).toBe(process.env);
       expect(shellPathCall?.timeoutMs).toBe(1234);
     } finally {
diff --git a/src/agents/bash-tools.test.ts b/src/agents/bash-tools.test.ts
index 3080fcde4ac8..cf1e9c5b3d4c 100644
--- a/src/agents/bash-tools.test.ts
+++ b/src/agents/bash-tools.test.ts
@@ -400,7 +400,9 @@ async function expectNotifyOnExitWake(tool: ExecToolInstance, expected: Record<s
   );
   try {
     await startBackgroundCommand(tool, shellEcho("notify"));
-    await expect.poll(() => wakeHandler.mock.calls[0]?.[0], NOTIFY_POLL_OPTIONS).toEqual(expected);
+    await expect
+      .poll(() => wakeHandler.mock.calls.at(0)?.[0], NOTIFY_POLL_OPTIONS)
+      .toEqual(expected);
   } finally {
     dispose();
   }