From c2b98dc70bac3b1dea41cd6e38f623b3ce2d5c2e Mon Sep 17 00:00:00 2001
From: Yury Semikhatsky <yurys@chromium.org>
Date: Tue, 22 Jul 2025 13:49:39 -0700
Subject: [PATCH] chore(extension): handle root session id in the relay (#737)

---
 extension/src/relayConnection.ts | 14 +++++---------
 src/extension/cdpRelay.ts        | 17 +++++++++++++----
 2 files changed, 18 insertions(+), 13 deletions(-)

diff --git a/extension/src/relayConnection.ts b/extension/src/relayConnection.ts
index 75b2881..0a9b964 100644
--- a/extension/src/relayConnection.ts
+++ b/extension/src/relayConnection.ts
@@ -38,7 +38,6 @@ type ProtocolResponse = {
 
 export class RelayConnection {
   private _debuggee: chrome.debugger.Debuggee = {};
-  private _rootSessionId = '';
   private _ws: WebSocket;
   private _eventListener: (source: chrome.debugger.DebuggerSession, method: string, params: any) => void;
   private _detachListener: (source: chrome.debugger.Debuggee, reason: string) => void;
@@ -56,11 +55,9 @@ export class RelayConnection {
   setConnectedTabId(tabId: number | null): void {
     if (!tabId) {
       this._debuggee = { };
-      this._rootSessionId = '';
       return;
     }
     this._debuggee = { tabId };
-    this._rootSessionId = `pw-tab-${tabId}`;
   }
 
   close(message?: string): void {
@@ -77,7 +74,7 @@ export class RelayConnection {
     if (source.tabId !== this._debuggee.tabId)
       return;
     debugLog('Forwarding CDP event:', method, params);
-    const sessionId = source.sessionId || this._rootSessionId;
+    const sessionId = source.sessionId;
     this._sendMessage({
       method: 'forwardCDPEvent',
       params: {
@@ -137,7 +134,6 @@ export class RelayConnection {
       await chrome.debugger.attach(this._debuggee, '1.3');
       const result: any = await chrome.debugger.sendCommand(this._debuggee, 'Target.getTargetInfo');
       return {
-        sessionId: this._rootSessionId,
         targetInfo: result?.targetInfo,
       };
     }
@@ -148,10 +144,10 @@ export class RelayConnection {
     if (message.method === 'forwardCDPCommand') {
       const { sessionId, method, params } = message.params;
       debugLog('CDP command:', method, params);
-      const debuggerSession: chrome.debugger.DebuggerSession = { ...this._debuggee };
-      // Pass session id, unless it's the root session.
-      if (sessionId && sessionId !== this._rootSessionId)
-        debuggerSession.sessionId = sessionId;
+      const debuggerSession: chrome.debugger.DebuggerSession = {
+        ...this._debuggee,
+        sessionId,
+      };
       // Forward CDP command to chrome.debugger
       return await chrome.debugger.sendCommand(
           debuggerSession,
diff --git a/src/extension/cdpRelay.ts b/src/extension/cdpRelay.ts
index b39746f..1cc8ec3 100644
--- a/src/extension/cdpRelay.ts
+++ b/src/extension/cdpRelay.ts
@@ -65,6 +65,7 @@ export class CDPRelayServer {
     // Page sessionId that should be used by this connection.
     sessionId: string;
   } | undefined;
+  private _nextSessionId: number = 1;
   private _extensionConnectionPromise: Promise<void>;
   private _extensionConnectionResolve: (() => void) | null = null;
 
@@ -190,8 +191,9 @@ export class CDPRelayServer {
   private _handleExtensionMessage(method: string, params: any) {
     switch (method) {
       case 'forwardCDPEvent':
+        const sessionId = params.sessionId || this._connectedTabInfo?.sessionId;
         this._sendToPlaywright({
-          sessionId: params.sessionId,
+          sessionId,
           method: params.method,
           params: params.params
         });
@@ -236,14 +238,18 @@ export class CDPRelayServer {
         if (sessionId)
           break;
         // Simulate auto-attach behavior with real target info
-        this._connectedTabInfo = await this._extensionConnection!.send('attachToTab');
+        const { targetInfo } = await this._extensionConnection!.send('attachToTab');
+        this._connectedTabInfo = {
+          targetInfo,
+          sessionId: `pw-tab-${this._nextSessionId++}`,
+        };
         debugLogger('Simulating auto-attach');
         this._sendToPlaywright({
           method: 'Target.attachedToTarget',
           params: {
-            sessionId: this._connectedTabInfo!.sessionId,
+            sessionId: this._connectedTabInfo.sessionId,
             targetInfo: {
-              ...this._connectedTabInfo!.targetInfo,
+              ...this._connectedTabInfo.targetInfo,
               attached: true,
             },
             waitingForDebugger: false
@@ -261,6 +267,9 @@ export class CDPRelayServer {
   private async _forwardToExtension(method: string, params: any, sessionId: string | undefined): Promise<any> {
     if (!this._extensionConnection)
       throw new Error('Extension not connected');
+    // Top level sessionId is only passed between the relay and the client.
+    if (this._connectedTabInfo?.sessionId === sessionId)
+      sessionId = undefined;
     return await this._extensionConnection.send('forwardCDPCommand', { sessionId, method, params });
   }