From 9623857d155b973f909acdccede7d0c75da27dcb Mon Sep 17 00:00:00 2001
From: Dmitry Gozman <dgozman@gmail.com>
Date: Wed, 23 Sep 2026 19:51:52 +0100
Subject: [PATCH] test(mcp): work around Chromium losing WebMCP tools in
 same-origin iframes

Fixes: https://github.com/microsoft/playwright/issues/42869
---
 tests/mcp/cli-webmcp.spec.ts | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/tests/mcp/cli-webmcp.spec.ts b/tests/mcp/cli-webmcp.spec.ts
index 3b447626ce8d5..70e55813b5d5b 100644
--- a/tests/mcp/cli-webmcp.spec.ts
+++ b/tests/mcp/cli-webmcp.spec.ts
@@ -49,6 +49,12 @@ function serveMain(server: any, body: string) {
   });
 }
 
+// Reloading the frame once replaces the initial blank page's window in Chromium
+// and works around the bug where tools do not register.
+function iframe(src: string) {
+  return `<iframe src="${src}" onload="if (!this.dataset.reloaded) { this.dataset.reloaded = '1'; this.contentWindow.location.reload(); }"></iframe>`;
+}
+
 test('webmcp-list and webmcp-call', async ({ cli, server, mcpBrowser }, testInfo) => {
   await writeWebMCPConfig(mcpBrowser, testInfo);
   serveMain(server, `<script>
@@ -136,7 +142,7 @@ test('webmcp-list stitches tools across frames', async ({ cli, server, mcpBrowse
   test.skip(mcpBrowser === 'firefox', 'Firefox does not support registering WebMCP tools in iframes yet, https://bugzilla.mozilla.org/show_bug.cgi?id=2019743');
   await writeWebMCPConfig(mcpBrowser, testInfo);
 
-  serveMain(server, `<script>${kRegisterAdd}</script><iframe src="/frame.html"></iframe>`);
+  serveMain(server, `<script>${kRegisterAdd}</script>${iframe('/frame.html')}`);
   server.setRoute('/frame.html', (req: any, res: any) => {
     res.writeHead(200, { 'Content-Type': 'text/html' });
     res.end(`<script>
@@ -171,7 +177,7 @@ test('webmcp-call disambiguates duplicate tool names by frame', async ({ cli, se
       async execute() { return { content: [{ type: 'text', text: '${text}' }] }; },
     });
   `;
-  serveMain(server, `<script>${registerEcho('main')}</script><iframe src="/frame.html"></iframe>`);
+  serveMain(server, `<script>${registerEcho('main')}</script>${iframe('/frame.html')}`);
   server.setRoute('/frame.html', (req: any, res: any) => {
     res.writeHead(200, { 'Content-Type': 'text/html' });
     res.end(`<script>${registerEcho('frame')}</script>`);
@@ -191,7 +197,7 @@ test('webmcp-call disambiguates same-name tools in identical same-origin frames'
 
   // Two iframes of the very same URL each own a tool called "echo", so the frame URL alone
   // cannot address them and the listing falls back to the frame position.
-  serveMain(server, `<iframe src="/widget.html"></iframe><iframe src="/widget.html"></iframe>`);
+  serveMain(server, `${iframe('/widget.html')}${iframe('/widget.html')}`);
   server.setRoute('/widget.html', (req: any, res: any) => {
     res.writeHead(200, { 'Content-Type': 'text/html' });
     res.end(`<script>