fix: race condition when opening attached windows (#2196)

Fixes microsoft/vscode#239769

Author: connor4312

CHANGELOG.md

@@ -4,11 +4,12 @@ This changelog records changes to stable releases since 1.50.2. "TBA" changes he
 
 ## 1.100 (April 2025)
 
-- fix: explicitly specify completion ranges ([[vscode#243409](https://github.com/microsoft/vscode/issues/243409)])
+- fix: explicitly specify completion ranges ([vscode#243409](https://github.com/microsoft/vscode/issues/243409))
 - fix: memory leak between debug sessions ([#2173](https://github.com/microsoft/vscode-js-debug/issues/2173))
 - fix: support `npm.scriptRunner: node`
 - fix: support "attach to node process" without wmic.exe and on arm64 ([vscode#244139](https://github.com/microsoft/vscode/issues/244139))
 - fix: support webview2 debugging on arm64
+- fix: race condition when opening attached windows ([vscode#239769](https://github.com/microsoft/vscode/issues/239769))
 - chore: enable experimental networking by default on recent Node versions
 
 ## 1.97 (January 2025)

src/targets/browser/browserTargetManager.ts

@@ -260,7 +260,9 @@ export class BrowserTargetManager implements IDisposable {
     // Also for service workers: https://bugs.chromium.org/p/chromium/issues/detail?id=1281013
     if (!jsTypes.has(type) || type === BrowserTargetType.ServiceWorker) {
       target.runIfWaitingForDebugger();
-    } else if (type === BrowserTargetType.Page && waitForDebuggerOnStart) {
+    } else if (
+      type === BrowserTargetType.Page && waitForDebuggerOnStart && !targetInfo.canAccessOpener
+    ) {
       cdp.Page.waitForDebugger({});
     }
 

src/targets/browser/browserTargets.ts

@@ -92,6 +92,7 @@ export class BrowserTarget implements ITarget {
   }
 
   _children: Map<Cdp.Target.TargetID, BrowserTarget> = new Map();
+  willWaitForDebugger: Promise<unknown> = Promise.resolve();
 
   public readonly sourcePathResolver = this._manager._sourcePathResolver;
 
@@ -150,7 +151,9 @@ export class BrowserTarget implements ITarget {
 
   async runIfWaitingForDebugger() {
     await Promise.all([
-      this._cdp.Runtime.runIfWaitingForDebugger({}),
+      // If it can access the opener, the debugger state is shared with the parent,
+      // and calling `runIfWaitingForDebugger` can resume the parent.
+      !this._targetInfo.canAccessOpener && this._cdp.Runtime.runIfWaitingForDebugger({}),
       this._cdp.Runtime.evaluate({ expression: signalReadyExpr() }),
     ]);
   }