Consistently guard restarts against concurrent auto updates (#21016)

packages/cli/src/utils/processUtils.test.ts

@@ -5,7 +5,11 @@
  */
 
 import { vi } from 'vitest';
-import { RELAUNCH_EXIT_CODE, relaunchApp } from './processUtils.js';
+import {
+  RELAUNCH_EXIT_CODE,
+  relaunchApp,
+  _resetRelaunchStateForTesting,
+} from './processUtils.js';
 import * as cleanup from './cleanup.js';
 import * as handleAutoUpdate from './handleAutoUpdate.js';
 
@@ -19,6 +23,10 @@ describe('processUtils', () => {
     .mockReturnValue(undefined as never);
   const runExitCleanup = vi.spyOn(cleanup, 'runExitCleanup');
 
+  beforeEach(() => {
+    _resetRelaunchStateForTesting();
+  });
+
   afterEach(() => vi.clearAllMocks());
 
   it('should wait for updates, run cleanup, and exit with the relaunch code', async () => {

packages/cli/src/utils/processUtils.ts

@@ -15,7 +15,16 @@ export const RELAUNCH_EXIT_CODE = 199;
 /**
  * Exits the process with a special code to signal that the parent process should relaunch it.
  */
+let isRelaunching = false;
+
+/** @internal only for testing */
+export function _resetRelaunchStateForTesting(): void {
+  isRelaunching = false;
+}
+
 export async function relaunchApp(): Promise<void> {
+  if (isRelaunching) return;
+  isRelaunching = true;
   await waitForUpdateCompletion();
   await runExitCleanup();
   process.exit(RELAUNCH_EXIT_CODE);