From f8dd0922336eaf967b65dd87e3978b453ca318ef Mon Sep 17 00:00:00 2001
From: "Julio C. Rocha" <julio.rocha@microsoft.com>
Date: Fri, 5 Jun 2026 18:01:31 -0700
Subject: [PATCH 01/15] Remove redundant condition
 Desktop.IntegrationTests.SkipRNTester

Modify Desktop.IntegrationTests.Filter instead.
---
 .ado/jobs/desktop-single.yml | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/.ado/jobs/desktop-single.yml b/.ado/jobs/desktop-single.yml
index 98da16e4abe..0dff5f80250 100644
--- a/.ado/jobs/desktop-single.yml
+++ b/.ado/jobs/desktop-single.yml
@@ -62,12 +62,6 @@ steps:
 
   - template: ../templates/apply-published-version-vars.yml
 
-  - ${{ if eq(variables['Desktop.IntegrationTests.SkipRNTester'], true) }}:
-    - pwsh: |
-        $newValue = '(FullyQualifiedName!~Microsoft::React::Test::RNTesterHeadlessTests::)&' + "$(Desktop.IntegrationTests.Filter)"
-        Write-Host "##vso[task.setvariable variable=Desktop.IntegrationTests.Filter]$newValue"
-      displayName: Update Desktop.IntegrationTests.Filter to exclude RNTester integration tests
-
   - template: ../templates/msbuild-sln.yml
     parameters:
       solutionDir: vnext

From 9163c69dce01951bd57d53eaf8d9f40206cc1ea0 Mon Sep 17 00:00:00 2001
From: "Julio C. Rocha" <julio.rocha@microsoft.com>
Date: Sat, 6 Jun 2026 16:36:37 -0700
Subject: [PATCH 02/15] Re-introduce WebSocket and WebSocketBlob tests

---
 .../RNTesterHeadlessTests.cpp                 |  61 ++++--
 vnext/overrides.json                          |   6 +-
 .../IntegrationTests/WebSocketBlobTest.js     | 206 ++++++------------
 .../src-win/IntegrationTests/WebSocketTest.js |  65 ++++++
 4 files changed, 168 insertions(+), 170 deletions(-)
 create mode 100644 vnext/src-win/IntegrationTests/WebSocketTest.js

diff --git a/vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp b/vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp
index f25eb3cdd4d..72f60f71b10 100644
--- a/vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp
+++ b/vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp
@@ -17,6 +17,35 @@ namespace msrn = winrt::Microsoft::ReactNative;
 
 namespace Microsoft::React::Test {
 
+namespace {
+void RunHeadlessJsTest(std::wstring_view jsBundle) {
+  TestModule::Reset();
+
+  winrt::handle instanceLoadedEvent{CreateEvent(nullptr, TRUE, FALSE, nullptr)};
+  bool instanceFailed{false};
+
+  auto holder = TestReactNativeHostHolder(
+      jsBundle, [&instanceLoadedEvent, &instanceFailed](msrn::ReactNativeHost const &host) noexcept {
+        host.InstanceSettings().InstanceLoaded(
+            [&instanceLoadedEvent, &instanceFailed](auto const &, msrn::InstanceLoadedEventArgs args) noexcept {
+              instanceFailed = args.Failed();
+              SetEvent(instanceLoadedEvent.get());
+            });
+      });
+
+  // First, wait for instance to load
+  WaitForSingleObject(instanceLoadedEvent.get(), INFINITE);
+  if (instanceFailed) {
+    auto err = holder.GetLastError();
+    auto msg = L"InstanceLoaded reported failure: " + (err.empty() ? L"(no error captured)" : err);
+    Assert::Fail(msg.c_str());
+  }
+
+  auto status = TestModule::AwaitCompletion();
+  Assert::IsTrue(status == TestStatus::Passed, L"Test did not pass (JS did not call markTestPassed within timeout)");
+}
+} // namespace
+
 TEST_CLASS (RNTesterHeadlessTests) {
   TEST_CLASS_INITIALIZE(Initialize) {
     // https://learn.microsoft.com/en-us/windows/windows-app-sdk/api/win32/mddbootstrap/nf-mddbootstrap-mddbootstrapinitialize2
@@ -37,31 +66,15 @@ TEST_CLASS (RNTesterHeadlessTests) {
   }
 
   TEST_METHOD(Dummy) {
-    TestModule::Reset();
-
-    winrt::handle instanceLoadedEvent{CreateEvent(nullptr, TRUE, FALSE, nullptr)};
-    bool instanceFailed{false};
-
-    auto holder = TestReactNativeHostHolder(
-        L"IntegrationTests/DummyTest",
-        [&instanceLoadedEvent, &instanceFailed](msrn::ReactNativeHost const &host) noexcept {
-          host.InstanceSettings().InstanceLoaded(
-              [&instanceLoadedEvent, &instanceFailed](auto const &, msrn::InstanceLoadedEventArgs args) noexcept {
-                instanceFailed = args.Failed();
-                SetEvent(instanceLoadedEvent.get());
-              });
-        });
-
-    // First, wait for instance to load
-    WaitForSingleObject(instanceLoadedEvent.get(), INFINITE);
-    if (instanceFailed) {
-      auto err = holder.GetLastError();
-      auto msg = L"InstanceLoaded reported failure: " + (err.empty() ? L"(no error captured)" : err);
-      Assert::Fail(msg.c_str());
-    }
+    RunHeadlessJsTest(L"IntegrationTests/DummyTest");
+  }
+
+  TEST_METHOD(WebSocket) {
+    RunHeadlessJsTest(L"IntegrationTests/WebSocketTest");
+  }
 
-    auto status = TestModule::AwaitCompletion();
-    Assert::IsTrue(status == TestStatus::Passed, L"Test did not pass (JS did not call markTestPassed within timeout)");
+  TEST_METHOD(WebSocketBlob) {
+    RunHeadlessJsTest(L"IntegrationTests/WebSocketBlobTest");
   }
 };
 
diff --git a/vnext/overrides.json b/vnext/overrides.json
index 4d3e420d543..cdc3a7f7caa 100644
--- a/vnext/overrides.json
+++ b/vnext/overrides.json
@@ -264,6 +264,10 @@
       "type": "platform",
       "file": "src-win/IntegrationTests/WebSocketBlobTest.js"
     },
+    {
+      "type": "platform",
+      "file": "src-win/IntegrationTests/WebSocketTest.js"
+    },
     {
       "type": "platform",
       "file": "src-win/IntegrationTests/WebSocketMultipleSendTest.js"
@@ -723,4 +727,4 @@
       "baseHash": "365c5df75b38b129d364af3f6700cb206ce5bd2a"
     }
   ]
-}
\ No newline at end of file
+}
diff --git a/vnext/src-win/IntegrationTests/WebSocketBlobTest.js b/vnext/src-win/IntegrationTests/WebSocketBlobTest.js
index 7b18bfe2c07..16033c93ff6 100644
--- a/vnext/src-win/IntegrationTests/WebSocketBlobTest.js
+++ b/vnext/src-win/IntegrationTests/WebSocketBlobTest.js
@@ -1,159 +1,75 @@
 /**
- * Copyright (c) Meta Platforms, Inc. and affiliates.
- *
- * This source code is licensed under the MIT license found in the
- * LICENSE file in the root directory of this source tree.
- *
+ * Copyright (c) Microsoft Corporation.
+ * Licensed under the MIT License.
  * @format
- * @flow
  */
 
 'use strict';
 
-const React = require('react');
-const ReactNative = require('react-native');
-const {AppRegistry, View} = ReactNative;
-const {TestModule} = ReactNative.NativeModules;
+const {TurboModuleRegistry} = require('react-native');
+const TestModule = TurboModuleRegistry.get('TestModule');
+
+if (!TestModule) {
+  throw new Error('TestModule is not available');
+}
 
 // eslint-disable-next-line @microsoft/sdl/no-insecure-url
-const DEFAULT_WS_URL = 'ws://localhost:5555/rnw/rntester/websocketbinarytest';
-
-const WS_EVENTS = ['close', 'error', 'message', 'open'];
-
-type State = {
-  url: string,
-  fetchStatus: ?string,
-  socket: ?WebSocket,
-  socketState: ?number,
-  lastSocketEvent: ?string,
-  lastMessage: ?Blob,
-  testMessage: Uint8Array,
-  testExpectedResponse: Uint8Array,
-  ...
-};
-
-class WebSocketBlobTest extends React.Component<{}, State> {
-  state: State = {
-    url: DEFAULT_WS_URL,
-    fetchStatus: null,
-    socket: null,
-    socketState: null,
-    lastSocketEvent: null,
-    lastMessage: null,
-    testMessage: new Uint8Array([1, 2, 3]),
-    testExpectedResponse: new Uint8Array([4, 5, 6, 7]),
-  };
-
-  _waitFor = (condition: any, timeout: any, callback: any) => {
-    let remaining = timeout;
-    const timeoutFunction = function () {
-      if (condition()) {
-        callback(true);
-        return;
-      }
-      remaining--;
-      if (remaining === 0) {
-        callback(false);
-      } else {
-        setTimeout(timeoutFunction, 1000);
-      }
-    };
-    setTimeout(timeoutFunction, 1000);
-  };
-
-  _connect = () => {
-    const socket = new WebSocket(this.state.url);
-    socket.binaryType = 'blob';
-    WS_EVENTS.forEach(ev => socket.addEventListener(ev, this._onSocketEvent));
-    this.setState({
-      socket,
-      socketState: socket.readyState,
-    });
-  };
-
-  _socketIsConnected = (): boolean => {
-    return this.state.socketState === 1; //'OPEN'
-  };
-
-  _socketIsDisconnected = (): boolean => {
-    return this.state.socketState === 3; //'CLOSED'
-  };
-
-  _disconnect = () => {
-    if (!this.state.socket) {
-      return;
-    }
-    this.state.socket.close();
-  };
-
-  _onSocketEvent = (event: any) => {
-    const state: any = {
-      socketState: event.target.readyState,
-      lastSocketEvent: event.type,
-    };
-    if (event.type === 'message') {
-      state.lastMessage = event.data;
-    }
-    this.setState(state);
-  };
-
-  _sendBinary = (message: Uint8Array) => {
-    if (!this.state.socket) {
-      return;
-    }
-    this.state.socket.send(message);
-  };
-
-  _sendTestMessage = () => {
-    this._sendBinary(this.state.testMessage);
-  };
-
-  _receivedTestExpectedResponse = (): boolean => {
-    // Can't iterate through Blob response. Blob.arrayBuffer() not supported.
-    return (
-      this.state.lastMessage?.size === this.state.testExpectedResponse.length
-    );
-  };
-
-  componentDidMount() {
-    this.testConnect();
+const WS_URL = 'ws://localhost:5555/rnw/rntester/websocketbinarytest';
+const TEST_MESSAGE = new Uint8Array([1, 2, 3]);
+const EXPECTED_SIZE = 4;
+
+let completed = false;
+const socket = new WebSocket(WS_URL);
+socket.binaryType = 'blob';
+
+const timeoutId = setTimeout(() => {
+  complete(false, 'timeout waiting for websocket response');
+}, 10000);
+
+function complete(passed, reason) {
+  if (completed) {
+    return;
   }
 
-  testConnect: () => void = () => {
-    this._connect();
-    this._waitFor(this._socketIsConnected, 5, connectSucceeded => {
-      if (!connectSucceeded) {
-        TestModule.markTestPassed(false);
-        return;
-      }
-      this.testSendAndReceive();
-    });
-  };
-
-  testSendAndReceive: () => void = () => {
-    this._sendTestMessage();
-    this._waitFor(this._receivedTestExpectedResponse, 5, messageReceived => {
-      if (!messageReceived) {
-        TestModule.markTestPassed(false);
-        return;
-      }
-      this.testDisconnect();
-    });
-  };
-
-  testDisconnect: () => void = () => {
-    this._disconnect();
-    this._waitFor(this._socketIsDisconnected, 5, disconnectSucceeded => {
-      TestModule.markTestPassed(disconnectSucceeded);
-    });
-  };
-  render(): React.Node {
-    return <View />;
+  completed = true;
+  clearTimeout(timeoutId);
+
+  if (!passed && reason) {
+    console.log('WebSocketBlobTest FAIL: ' + reason);
   }
-} // class WebSocketBlobTest
 
-WebSocketBlobTest.displayName = 'WebSocketBlobTest';
+  TestModule.markTestPassed(passed);
+}
+
+socket.addEventListener('open', () => {
+  socket.send(TEST_MESSAGE);
+});
 
-AppRegistry.registerComponent('WebSocketBlobTest', () => WebSocketBlobTest);
+socket.addEventListener('message', event => {
+  const data = event.data;
 
-module.exports = WebSocketBlobTest;
+  if (!(data instanceof Blob)) {
+    complete(false, 'expected Blob response');
+    socket.close();
+    return;
+  }
+
+  if (data.size !== EXPECTED_SIZE) {
+    complete(false, 'unexpected response size');
+    socket.close();
+    return;
+  }
+
+  complete(true);
+  socket.close();
+});
+
+socket.addEventListener('error', () => {
+  complete(false, 'websocket error');
+});
+
+socket.addEventListener('close', () => {
+  if (!completed) {
+    complete(false, 'socket closed before completing test');
+  }
+});
diff --git a/vnext/src-win/IntegrationTests/WebSocketTest.js b/vnext/src-win/IntegrationTests/WebSocketTest.js
new file mode 100644
index 00000000000..1dc16199a89
--- /dev/null
+++ b/vnext/src-win/IntegrationTests/WebSocketTest.js
@@ -0,0 +1,65 @@
+/**
+ * Copyright (c) Microsoft Corporation.
+ * Licensed under the MIT License.
+ * @format
+ */
+
+'use strict';
+
+const {TurboModuleRegistry} = require('react-native');
+const TestModule = TurboModuleRegistry.get('TestModule');
+
+if (!TestModule) {
+  throw new Error('TestModule is not available');
+}
+
+// eslint-disable-next-line @microsoft/sdl/no-insecure-url
+const WS_URL = 'ws://localhost:5555/';
+const TEST_MESSAGE = 'testMessage';
+const EXPECTED_RESPONSE = 'testMessage_response';
+
+let completed = false;
+const socket = new WebSocket(WS_URL);
+const timeoutId = setTimeout(() => {
+  complete(false, 'timeout waiting for websocket response');
+}, 10000);
+
+function complete(passed, reason) {
+  if (completed) {
+    return;
+  }
+
+  completed = true;
+  clearTimeout(timeoutId);
+
+  if (!passed && reason) {
+    console.log('WebSocketTest FAIL: ' + reason);
+  }
+
+  TestModule.markTestPassed(passed);
+}
+
+socket.addEventListener('open', () => {
+  socket.send(TEST_MESSAGE);
+});
+
+socket.addEventListener('message', event => {
+  if (event.data !== EXPECTED_RESPONSE) {
+    complete(false, 'unexpected response payload');
+    socket.close();
+    return;
+  }
+
+  complete(true);
+  socket.close();
+});
+
+socket.addEventListener('error', () => {
+  complete(false, 'websocket error');
+});
+
+socket.addEventListener('close', () => {
+  if (!completed) {
+    complete(false, 'socket closed before completing test');
+  }
+});

From a76cd6bb9224299505f8f83fb898b379df9e0a24 Mon Sep 17 00:00:00 2001
From: Julio Cesar Rocha <julio.rocha@microsoft.com>
Date: Sun, 7 Jun 2026 00:21:38 -0700
Subject: [PATCH 03/15] Make WSBlob test compare contents

---
 .../RNTesterHeadlessTests.cpp                 | 31 ++---------
 .../IntegrationTests/WebSocketBlobTest.js     | 52 +++++++++++++++++--
 2 files changed, 53 insertions(+), 30 deletions(-)

diff --git a/vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp b/vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp
index aa68b301c8c..6fc8b149ac0 100644
--- a/vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp
+++ b/vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp
@@ -8,6 +8,7 @@
 #include <MddBootstrap.h>
 #include <WindowsAppSDK-VersionInfo.h>
 
+#include <CppRuntimeOptions.h>
 #include "Modules/TestModule.h"
 #include "TestReactNativeHostHolder.h"
 
@@ -59,6 +60,8 @@ TEST_CLASS (RNTesterHeadlessTests) {
             MddBootstrapInitializeOptions::MddBootstrapInitializeOptions_None))) {
       throw std::exception("Could not initialize Windows App runtime");
     }
+
+    SetRuntimeOptionBool("WebSocket.ResourceV2", true);
   }
 
   TEST_CLASS_CLEANUP(Cleanup) {
@@ -77,34 +80,8 @@ TEST_CLASS (RNTesterHeadlessTests) {
     RunHeadlessJsTest(L"IntegrationTests/WebSocketBlobTest");
   }
 
-  BEGIN_TEST_METHOD_ATTRIBUTE(WebSocketArrayBuffer)
-  TEST_IGNORE()
-  END_TEST_METHOD_ATTRIBUTE()
   TEST_METHOD(WebSocketArrayBuffer) {
-    TestModule::Reset();
-
-    winrt::handle instanceLoadedEvent{CreateEvent(nullptr, TRUE, FALSE, nullptr)};
-    bool instanceFailed{false};
-
-    auto holder = TestReactNativeHostHolder(
-        L"IntegrationTests/WebSocketArrayBufferTest",
-        [&instanceLoadedEvent, &instanceFailed](msrn::ReactNativeHost const &host) noexcept {
-          host.InstanceSettings().InstanceLoaded(
-              [&instanceLoadedEvent, &instanceFailed](auto const &, msrn::InstanceLoadedEventArgs args) noexcept {
-                instanceFailed = args.Failed();
-                SetEvent(instanceLoadedEvent.get());
-              });
-        });
-
-    WaitForSingleObject(instanceLoadedEvent.get(), INFINITE);
-    if (instanceFailed) {
-      auto err = holder.GetLastError();
-      auto msg = L"InstanceLoaded reported failure: " + (err.empty() ? L"(no error captured)" : err);
-      Assert::Fail(msg.c_str());
-    }
-
-    auto status = TestModule::AwaitCompletion();
-    Assert::IsTrue(status == TestStatus::Passed, L"Test did not pass (JS did not call markTestPassed within timeout)");
+    RunHeadlessJsTest(L"IntegrationTests/WebSocketArrayBufferTest");
   }
 };
 
diff --git a/vnext/src-win/IntegrationTests/WebSocketBlobTest.js b/vnext/src-win/IntegrationTests/WebSocketBlobTest.js
index 16033c93ff6..1b7b675276b 100644
--- a/vnext/src-win/IntegrationTests/WebSocketBlobTest.js
+++ b/vnext/src-win/IntegrationTests/WebSocketBlobTest.js
@@ -16,7 +16,9 @@ if (!TestModule) {
 // eslint-disable-next-line @microsoft/sdl/no-insecure-url
 const WS_URL = 'ws://localhost:5555/rnw/rntester/websocketbinarytest';
 const TEST_MESSAGE = new Uint8Array([1, 2, 3]);
-const EXPECTED_SIZE = 4;
+// Expected bytes come from RNTesterIntegrationTests.WebSocketBinaryTest outgoingBytes.
+const EXPECTED_BYTES = new Uint8Array([4, 5, 6, 7]);
+const EXPECTED_SIZE = EXPECTED_BYTES.length;
 
 let completed = false;
 const socket = new WebSocket(WS_URL);
@@ -41,6 +43,25 @@ function complete(passed, reason) {
   TestModule.markTestPassed(passed);
 }
 
+function decodeBlobToBytes(blob, onSuccess, onError) {
+  if (typeof blob.arrayBuffer === 'function') {
+    blob
+      .arrayBuffer()
+      .then(buffer => onSuccess(new Uint8Array(buffer)))
+      .catch(onError);
+    return;
+  }
+
+  const reader = new FileReader();
+  reader.onload = () => {
+    onSuccess(new Uint8Array(reader.result));
+  };
+  reader.onerror = () => {
+    onError(reader.error || new Error('failed to read blob'));
+  };
+  reader.readAsArrayBuffer(blob);
+}
+
 socket.addEventListener('open', () => {
   socket.send(TEST_MESSAGE);
 });
@@ -60,8 +81,33 @@ socket.addEventListener('message', event => {
     return;
   }
 
-  complete(true);
-  socket.close();
+  decodeBlobToBytes(
+    data,
+    bytes => {
+      for (let i = 0; i < EXPECTED_BYTES.length; i++) {
+        if (bytes[i] !== EXPECTED_BYTES[i]) {
+          complete(
+            false,
+            'unexpected response byte at index ' +
+              i +
+              ': expected ' +
+              EXPECTED_BYTES[i] +
+              ', got ' +
+              bytes[i],
+          );
+          socket.close();
+          return;
+        }
+      }
+
+      complete(true);
+      socket.close();
+    },
+    error => {
+      complete(false, 'failed to decode blob: ' + String(error));
+      socket.close();
+    },
+  );
 });
 
 socket.addEventListener('error', () => {

From 0b357c675f15ec45a6b5c7060e08bcda976d25ea Mon Sep 17 00:00:00 2001
From: Julio Cesar Rocha <julio.rocha@microsoft.com>
Date: Sun, 7 Jun 2026 00:30:51 -0700
Subject: [PATCH 04/15] Rename method to RunTest

---
 .../Desktop.IntegrationTests/RNTesterHeadlessTests.cpp | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp b/vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp
index 6fc8b149ac0..a85bc724fa8 100644
--- a/vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp
+++ b/vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp
@@ -19,7 +19,7 @@ namespace msrn = winrt::Microsoft::ReactNative;
 namespace Microsoft::React::Test {
 
 namespace {
-void RunHeadlessJsTest(std::wstring_view jsBundle) {
+void RunTest(std::wstring_view jsBundle) {
   TestModule::Reset();
 
   winrt::handle instanceLoadedEvent{CreateEvent(nullptr, TRUE, FALSE, nullptr)};
@@ -69,19 +69,19 @@ TEST_CLASS (RNTesterHeadlessTests) {
   }
 
   TEST_METHOD(Dummy) {
-    RunHeadlessJsTest(L"IntegrationTests/DummyTest");
+    RunTest(L"IntegrationTests/DummyTest");
   }
 
   TEST_METHOD(WebSocket) {
-    RunHeadlessJsTest(L"IntegrationTests/WebSocketTest");
+    RunTest(L"IntegrationTests/WebSocketTest");
   }
 
   TEST_METHOD(WebSocketBlob) {
-    RunHeadlessJsTest(L"IntegrationTests/WebSocketBlobTest");
+    RunTest(L"IntegrationTests/WebSocketBlobTest");
   }
 
   TEST_METHOD(WebSocketArrayBuffer) {
-    RunHeadlessJsTest(L"IntegrationTests/WebSocketArrayBufferTest");
+    RunTest(L"IntegrationTests/WebSocketArrayBufferTest");
   }
 };
 

From 8cb3ab1fefb9376f280bdda30836f60b230a50ac Mon Sep 17 00:00:00 2001
From: Julio Cesar Rocha <julio.rocha@microsoft.com>
Date: Sun, 7 Jun 2026 00:43:09 -0700
Subject: [PATCH 05/15] Handle initial message from default endpoint

---
 .../src-win/IntegrationTests/WebSocketTest.js | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/vnext/src-win/IntegrationTests/WebSocketTest.js b/vnext/src-win/IntegrationTests/WebSocketTest.js
index 1dc16199a89..b1975486599 100644
--- a/vnext/src-win/IntegrationTests/WebSocketTest.js
+++ b/vnext/src-win/IntegrationTests/WebSocketTest.js
@@ -17,13 +17,24 @@ if (!TestModule) {
 const WS_URL = 'ws://localhost:5555/';
 const TEST_MESSAGE = 'testMessage';
 const EXPECTED_RESPONSE = 'testMessage_response';
+const INITIAL_SERVER_GREETING = 'hello';
 
 let completed = false;
+let messageSent = false;
 const socket = new WebSocket(WS_URL);
 const timeoutId = setTimeout(() => {
   complete(false, 'timeout waiting for websocket response');
 }, 10000);
 
+function sendTestMessageIfNeeded() {
+  if (messageSent || socket.readyState !== WebSocket.OPEN) {
+    return;
+  }
+
+  messageSent = true;
+  socket.send(TEST_MESSAGE);
+}
+
 function complete(passed, reason) {
   if (completed) {
     return;
@@ -40,10 +51,14 @@ function complete(passed, reason) {
 }
 
 socket.addEventListener('open', () => {
-  socket.send(TEST_MESSAGE);
+  sendTestMessageIfNeeded();
 });
 
 socket.addEventListener('message', event => {
+  if (event.data === INITIAL_SERVER_GREETING) {
+    return;
+  }
+
   if (event.data !== EXPECTED_RESPONSE) {
     complete(false, 'unexpected response payload');
     socket.close();
@@ -63,3 +78,5 @@ socket.addEventListener('close', () => {
     complete(false, 'socket closed before completing test');
   }
 });
+
+sendTestMessageIfNeeded();

From ce92f29b93fbaf5ad16de50f5c878ce7aa75961d Mon Sep 17 00:00:00 2001
From: Julio Cesar Rocha <julio.rocha@microsoft.com>
Date: Sun, 7 Jun 2026 00:52:18 -0700
Subject: [PATCH 06/15] Change files

---
 ...ative-windows-5ebbf393-f061-48ee-aa68-dfdd086cfbbd.json | 7 +++++++
 1 file changed, 7 insertions(+)
 create mode 100644 change/react-native-windows-5ebbf393-f061-48ee-aa68-dfdd086cfbbd.json

diff --git a/change/react-native-windows-5ebbf393-f061-48ee-aa68-dfdd086cfbbd.json b/change/react-native-windows-5ebbf393-f061-48ee-aa68-dfdd086cfbbd.json
new file mode 100644
index 00000000000..dc96d8037a6
--- /dev/null
+++ b/change/react-native-windows-5ebbf393-f061-48ee-aa68-dfdd086cfbbd.json
@@ -0,0 +1,7 @@
+{
+  "type": "prerelease",
+  "comment": "Re-introduce WebSocket JS integration tests",
+  "packageName": "react-native-windows",
+  "email": "julio.rocha@microsoft.com",
+  "dependentChangeType": "patch"
+}

From 2d11bf36ea7b16edefd8ffa2bbc0d04ce186d079 Mon Sep 17 00:00:00 2001
From: Julio Cesar Rocha <julio.rocha@microsoft.com>
Date: Mon, 8 Jun 2026 00:01:21 -0700
Subject: [PATCH 07/15] Migrate XHR test

---
 .../RNTesterHeadlessTests.cpp                 |  4 +
 vnext/TestWebSite/wwwroot/static/sample.txt   |  2 +-
 vnext/src-win/IntegrationTests/XHRTest.js     | 89 ++++---------------
 3 files changed, 24 insertions(+), 71 deletions(-)

diff --git a/vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp b/vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp
index a85bc724fa8..f81d2c48616 100644
--- a/vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp
+++ b/vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp
@@ -83,6 +83,10 @@ TEST_CLASS (RNTesterHeadlessTests) {
   TEST_METHOD(WebSocketArrayBuffer) {
     RunTest(L"IntegrationTests/WebSocketArrayBufferTest");
   }
+
+  TEST_METHOD(XHR) {
+    RunTest(L"IntegrationTests/XHRTest");
+  }
 };
 
 } // namespace Microsoft::React::Test
diff --git a/vnext/TestWebSite/wwwroot/static/sample.txt b/vnext/TestWebSite/wwwroot/static/sample.txt
index 5bd282c8887..47e646f426f 100644
--- a/vnext/TestWebSite/wwwroot/static/sample.txt
+++ b/vnext/TestWebSite/wwwroot/static/sample.txt
@@ -1 +1 @@
-Sample Static Text File
+Sample Static Text File
\ No newline at end of file
diff --git a/vnext/src-win/IntegrationTests/XHRTest.js b/vnext/src-win/IntegrationTests/XHRTest.js
index a03ba97c658..2b85a9a0f3d 100644
--- a/vnext/src-win/IntegrationTests/XHRTest.js
+++ b/vnext/src-win/IntegrationTests/XHRTest.js
@@ -2,81 +2,30 @@
  * Copyright (c) Microsoft Corporation.
  * Licensed under the MIT License.
  * @format
- * @flow
  */
 'use strict';
 
-const React = require('react');
-const ReactNative = require('react-native');
+const {TurboModuleRegistry} = require('react-native');
 
-const {AppRegistry, View} = ReactNative;
+const TestModule = TurboModuleRegistry.get('TestModule');
 
-const {TestModule} = ReactNative.NativeModules;
-
-type State = {
-  statusCode: number,
-  xhr: XMLHttpRequest,
-};
-
-class XHRTest extends React.Component<{...}, State> {
-  state: State = {
-    statusCode: 0,
-    xhr: new XMLHttpRequest(),
-  };
-
-  _get = () => {
-    this.state.xhr.onloadend = () => {
-      this.setState({
-        statusCode: this.state.xhr.status,
-      });
-    };
-    this.state.xhr.open(
-      'GET',
-      'https://raw.githubusercontent.com/microsoft/react-native-windows/react-native-windows_v0.67.1/NuGet.Config',
-    );
-    this.state.xhr.setRequestHeader('Accept-Encoding', 'utf-8');
-    this.state.xhr.send();
-  };
-
-  _getSucceeded = (): boolean => {
-    console.log(
-      `_getSucceeded [${this.state.statusCode}],[${this.state.xhr.responseText.length}]`,
-    );
-    return (
-      this.state.statusCode === 200 &&
-      this.state.xhr.responseText.length === 387
-    );
-  };
-
-  _waitFor = (condition: any, timeout: any, callback: any) => {
-    let remaining = timeout;
-    const timeoutFunction = function () {
-      if (condition()) {
-        callback(true);
-        return;
-      }
-      remaining--;
-      if (remaining === 0) {
-        callback(false);
-      } else {
-        setTimeout(timeoutFunction, 1000);
-      }
-    };
-    setTimeout(timeoutFunction, 1000);
-  };
-
-  componentDidMount() {
-    this._get();
-    this._waitFor(this._getSucceeded, 5, doneSucceeded => {
-      TestModule.markTestPassed(doneSucceeded);
-    });
-  }
-
-  render(): React.Node {
-    return <View />;
-  }
+if (!TestModule) {
+  throw new Error('TestModule is not available');
 }
 
-AppRegistry.registerComponent('XHRTest', () => XHRTest);
+const URL = 'http://localhost:5555/static/sample.txt';
+const EXPECTED_CONTENT = 'Sample Static Text File';
+
+const xhr = new XMLHttpRequest();
+xhr.onloadend = () => {
+  const responseText = xhr.responseText || '';
+  const passed =
+    xhr.status === 200 && responseText === EXPECTED_CONTENT;
+  TestModule.markTestPassed(passed);
+};
+xhr.onerror = () => {
+  TestModule.markTestPassed(false);
+};
 
-module.exports = XHRTest;
+xhr.open('GET', URL);
+xhr.send();

From f3d3515826c014f8af0cd551297ab1776dd41ad0 Mon Sep 17 00:00:00 2001
From: Julio Cesar Rocha <julio.rocha@microsoft.com>
Date: Mon, 8 Jun 2026 00:15:39 -0700
Subject: [PATCH 08/15] Port Fetch test

---
 .../RNTesterHeadlessTests.cpp                 | 12 ++--
 vnext/src-win/IntegrationTests/FetchTest.js   | 57 ++++++-------------
 2 files changed, 24 insertions(+), 45 deletions(-)

diff --git a/vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp b/vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp
index f81d2c48616..0a5a548a22b 100644
--- a/vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp
+++ b/vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp
@@ -72,6 +72,14 @@ TEST_CLASS (RNTesterHeadlessTests) {
     RunTest(L"IntegrationTests/DummyTest");
   }
 
+  TEST_METHOD(Fetch) {
+    RunTest(L"IntegrationTests/FetchTest");
+  }
+
+  TEST_METHOD(XHR) {
+    RunTest(L"IntegrationTests/XHRTest");
+  }
+
   TEST_METHOD(WebSocket) {
     RunTest(L"IntegrationTests/WebSocketTest");
   }
@@ -83,10 +91,6 @@ TEST_CLASS (RNTesterHeadlessTests) {
   TEST_METHOD(WebSocketArrayBuffer) {
     RunTest(L"IntegrationTests/WebSocketArrayBufferTest");
   }
-
-  TEST_METHOD(XHR) {
-    RunTest(L"IntegrationTests/XHRTest");
-  }
 };
 
 } // namespace Microsoft::React::Test
diff --git a/vnext/src-win/IntegrationTests/FetchTest.js b/vnext/src-win/IntegrationTests/FetchTest.js
index 79c666fa581..ff645f5516a 100644
--- a/vnext/src-win/IntegrationTests/FetchTest.js
+++ b/vnext/src-win/IntegrationTests/FetchTest.js
@@ -2,52 +2,27 @@
  * Copyright (c) Microsoft Corporation.
  * Licensed under the MIT License.
  * @format
- * @flow
  */
 
 'use strict';
 
-const React = require('react');
-const ReactNative = require('react-native');
+const {TurboModuleRegistry} = require('react-native');
 
-const {AppRegistry, View} = ReactNative;
+const TestModule = TurboModuleRegistry.get('TestModule');
 
-const {TestModule} = ReactNative.NativeModules;
-
-const uri =
-  'https://raw.githubusercontent.com/microsoft/react-native-windows/main/.yarnrc.yml';
-const expectedContent = 'enableScripts: false';
-
-type State = {
-  uri: string,
-  expected: string,
-  content: string,
-};
-
-class FetchTest extends React.Component<{...}, State> {
-  state: State = {
-    uri: 'https://raw.githubusercontent.com/microsoft/react-native-windows/main/.yarnrc.yml',
-    expected: 'enableScripts: false',
-    content: '',
-  };
-
-  async componentDidMount() {
-    const response = await fetch(uri);
-    const text = await response.text();
-    this.setState({content: text});
-
-    if (this.state.content === expectedContent) {
-      TestModule.markTestPassed(true);
-    } else {
-      TestModule.markTestPassed(false);
-    }
-  }
-
-  render(): React.Node {
-    return <View />;
-  }
+if (!TestModule) {
+  throw new Error('TestModule is not available');
 }
 
-AppRegistry.registerComponent('FetchTest', () => FetchTest);
-
-module.exports = FetchTest;
+const URL = 'http://localhost:5555/static/sample.txt';
+const EXPECTED_CONTENT = 'Sample Static Text File';
+
+fetch(URL)
+  .then(response => response.text())
+  .then(text => {
+    const passed = text === EXPECTED_CONTENT;
+    TestModule.markTestPassed(passed);
+  })
+  .catch(() => {
+    TestModule.markTestPassed(false);
+  });

From 69deaa139cdc0b88473276ac0bc7266f333fad67 Mon Sep 17 00:00:00 2001
From: Julio Cesar Rocha <julio.rocha@microsoft.com>
Date: Mon, 8 Jun 2026 00:31:25 -0700
Subject: [PATCH 09/15] Port Blob test

---
 .../RNTesterHeadlessTests.cpp                 |   4 +
 vnext/src-win/IntegrationTests/BlobTest.js    | 161 +++++++-----------
 2 files changed, 66 insertions(+), 99 deletions(-)

diff --git a/vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp b/vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp
index 0a5a548a22b..7a293454f94 100644
--- a/vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp
+++ b/vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp
@@ -91,6 +91,10 @@ TEST_CLASS (RNTesterHeadlessTests) {
   TEST_METHOD(WebSocketArrayBuffer) {
     RunTest(L"IntegrationTests/WebSocketArrayBufferTest");
   }
+
+  TEST_METHOD(Blob) {
+    RunTest(L"IntegrationTests/BlobTest");
+  }
 };
 
 } // namespace Microsoft::React::Test
diff --git a/vnext/src-win/IntegrationTests/BlobTest.js b/vnext/src-win/IntegrationTests/BlobTest.js
index 47cf5ecb81e..363ee3c99f7 100644
--- a/vnext/src-win/IntegrationTests/BlobTest.js
+++ b/vnext/src-win/IntegrationTests/BlobTest.js
@@ -2,115 +2,78 @@
  * Copyright (c) Microsoft Corporation.
  * Licensed under the MIT License.
  * @format
- * @flow
  */
 'use strict';
 
-const React = require('react');
-const ReactNative = require('react-native');
+const {TurboModuleRegistry} = require('react-native');
 
-const {AppRegistry, View} = ReactNative;
+const TestModule = TurboModuleRegistry.get('TestModule');
 
-const {TestModule} = ReactNative.NativeModules;
-
-type State = {
-  statusCode: number,
-  xhr: XMLHttpRequest,
-  expected: string,
-};
-
-class BlobTest extends React.Component<{...}, State> {
-  state: State = {
-    statusCode: 0,
-    xhr: new XMLHttpRequest(),
-    // http://localhost:5555/static/react.png
-    // cspell:disable
-    expected:
-      'data:application/octet-stream;base64,' +
-      'iVBORw0KGgoAAAANSUhEUgAAABcAAAAVCAYAAACt4nWrAAABbWlDQ1BpY2MAACiRdZG9S0JR' +
-      'GMZ/alGk4VBDRJCDRYNCFEhj2dAiIWaQ1aLXr0Cvl3uViNagpUFoiFr6GvoPag1aC4KgCCLa' +
-      '2vtaQm7vUUGJOpdz3x/POc/Le58LzkhBK1od01DUy2ZsLuxbSiz7ul5x48RFiOGkZhkz0WiE' +
-      'f9fXPQ5V74Kq1//3/lzudMbSwNEtHNIMsyws0xBZLxuKd4T7tXwyLXwkHDBlQOFrpaca/KI4' +
-      '1+APxWY8NgtO1dOXa+NUG2t5syg8JuwvFipacx71JZ6MvrggdVD2EBYx5gjjI0WFNQqUCUrV' +
-      'JbO/feN13zwl8WjyNtjAFEeOvHgDolaka0ZqVvSMPAU2VO6/87SykxON7p4wdD7b9vsIdO1C' +
-      'rWrb38e2XTsB1xNc6i1/SXKa+hS92tL8h+DdgvOrlpbag4ttGHg0kmayLrlkO7NZeDuD3gT0' +
-      '3ULPSiOr5jmnDxDflF90A/sHMCr3vas/DkpoELlQjWUAAAAJcEhZcwAAnXsAAJ17ATyfd8QA' +
-      'AARxSURBVDgRbVRbbFRVFN373Hs7fSBorI/S2FLK9GETQgHjBwlg+fABQT78METKTBtrookR' +
-      'QgJFDcUP2wRiUKMfVZnCxBq1Rk0MyA81fjQxhQKJ2naGUDum8a1AW9qZe+/ZrjP0NreOJzmz' +
-      'z36te86avTfT/6y2tHtIhPbD5WIPiGN399Xwr0FobELuZ9frhP4UtsNMb5yMOj2BP5AqOASy' +
-      'PZ1rBvBeYrsJoE2wT3POuxRPeTtMjJFGx/Fm3m/iEB9L5dYZf3jZYcWcRXOLECX76viPBd8r' +
-      'e9PZj5SogXja3Uoi20npbYlo5McgNzbuJhXxNuiXA5uRBTfXROWK83Qsxp2KRn4QVm+T8IvE' +
-      '6q0wsAkCLZ7JW0xYOBSAK0U3NFNpOBA33sKiO4W87XjaYaOH/SxUavLCNnMuoIU0X1GsW48M' +
-      'ij1Zla1R2qoxNIEOPN1ai/PHxPRJLOU+Q5b/U3UmMvEzu/Wa+dR/wTlsiI/PrRZVtBO37AbA' +
-      'LAn9gl2Od8/g6YP4R6ZBwh0iukWEy2D7EwAV+GAZaOu0/dyX7zeUTASYefD2a1KtXfcYAB9i' +
-      '5n4A7mCL9vs+r2CSHqfMXtdbybeCpD1XpMwu8S8D9CB5Mq0sOU6KvxKR3cgd9mznQLKWM6pt' +
-      'LLfR9/xBVjQkjtOIen0ZnPeLx0/iy8eEqaN3Jc3Fx92j2BeMTK6lW6ykw/jZ4p3C/KHJM/kG' +
-      'x/L9bwwux1PuCGk6kGhwzgc3ax2Vuy3Lvwaev0/UO5vaUrmYECcCP14TP1lX1BdPe0OIafJ9' +
-      'e/XpRv4r8MfH3BbU4XFTLdUSsUcCh5GnG+hviCwAM0aHrDUyWCE9A2d2IT5w0wJeFaMBulFG' +
-      'DbayY721nC8nlNqjSHod0atUzo761vxytuzvoN+L/bv43sOaiqcty0uBmklQ15mIOucMOkbD' +
-      'ncrzElrTGJuSy1R6XbA/Syw9YjsJdt0TLOo8kjbB7ifq7OfzSb7XrC37EubMdYyBd+GzcIkh' +
-      'xG0lx9pHOa8NFXQQ9veqpuyufLVAofar82t8sV9CQzyGRqkSpZIW6Ytacxca+TVluV9ridxQ' +
-      'nF3ha/U4C79qKTnikdrIWu9B52ZQbWcVe29+sKb4qsFcBDeKWfF09kES1S8svaTVejDeiNts' +
-      'QOgUzsshb+IPrcSwugjuRzFnRnD753ySp5N1kdHbKLd/CzoUN9qM+j3XFy0yz84vVNQJIn3P' +
-      'TNRpXZZ2k5r4t756Z1/gR7eucoi2QF8CXjBbkLgSN7keJBo5U2J3YmhVLEt7F9Ct982W2IfD' +
-      'fhOPjq1YYoNSAA7O0ckyFw789AGeA4HDoKca9uG8Hgow8eAXD166CsANj4hqDsJax6UStHwG' +
-      'fb1datcBYgNoGDD2IIY1NePFY4EeyII/tGNKSt1ZbwQz5lst5LPILtz6HZRWz9FH2Fso3UP4' +
-      'yAto+y8w+y3MlM2grrngRcFXwrJjXMpdcnexUnPzRdaZ/mr+J+w3592Tcldxzn9CtC7xtfN5' +
-      'uP2D2H8BsGL5W7blULYAAAAASUVORK5CYII=',
-    // cspell:enable
-  };
+if (!TestModule) {
+  throw new Error('TestModule is not available');
+}
 
-  _get = () => {
-    this.state.xhr.onloadend = () => {
-      this.setState({
-        statusCode: this.state.xhr.status,
-      });
-    };
-    this.state.xhr.open('GET', 'http://localhost:5555/static/react.png');
-    this.state.xhr.setRequestHeader('Accept-Encoding', 'utf-8');
-    this.state.xhr.responseType = 'blob';
-    this.state.xhr.send();
-  };
+const URL = 'http://localhost:5555/static/react.png';
 
-  _getSucceeded = (): boolean => {
-    return this.state.statusCode === 200 && this.state.xhr.response !== null;
-  };
+// cspell:disable
+const EXPECTED_DATA_URL =
+  'data:application/octet-stream;base64,' +
+  'iVBORw0KGgoAAAANSUhEUgAAABcAAAAVCAYAAACt4nWrAAABbWlDQ1BpY2MAACiRdZG9S0JR' +
+  'GMZ/alGk4VBDRJCDRYNCFEhj2dAiIWaQ1aLXr0Cvl3uViNagpUFoiFr6GvoPag1aC4KgCCLa' +
+  '2vtaQm7vUUGJOpdz3x/POc/Le58LzkhBK1od01DUy2ZsLuxbSiz7ul5x48RFiOGkZhkz0WiE' +
+  'f9fXPQ5V74Kq1//3/lzudMbSwNEtHNIMsyws0xBZLxuKd4T7tXwyLXwkHDBlQOFrpaca/KI4' +
+  '1+APxWY8NgtO1dOXa+NUG2t5syg8JuwvFipacx71JZ6MvrggdVD2EBYx5gjjI0WFNQqUCUrV' +
+  'JbO/feN13zwl8WjyNtjAFEeOvHgDolaka0ZqVvSMPAU2VO6/87SykxON7p4wdD7b9vsIdO1C' +
+  'rWrb38e2XTsB1xNc6i1/SXKa+hS92tL8h+DdgvOrlpbag4ttGHg0kmayLrlkO7NZeDuD3gT0' +
+  '3ULPSiOr5jmnDxDflF90A/sHMCr3vas/DkpoELlQjWUAAAAJcEhZcwAAnXsAAJ17ATyfd8QA' +
+  'AARxSURBVDgRbVRbbFRVFN373Hs7fSBorI/S2FLK9GETQgHjBwlg+fABQT78METKTBtrookR' +
+  'QgJFDcUP2wRiUKMfVZnCxBq1Rk0MyA81fjQxhQKJ2naGUDum8a1AW9qZe+/ZrjP0NreOJzmz' +
+  'z36te86avTfT/6y2tHtIhPbD5WIPiGN399Xwr0FobELuZ9frhP4UtsNMb5yMOj2BP5AqOASy' +
+  'PZ1rBvBeYrsJoE2wT3POuxRPeTtMjJFGx/Fm3m/iEB9L5dYZf3jZYcWcRXOLECX76viPBd8r' +
+  'e9PZj5SogXja3Uoi20npbYlo5McgNzbuJhXxNuiXA5uRBTfXROWK83Qsxp2KRn4QVm+T8IvE' +
+  '6q0wsAkCLZ7JW0xYOBSAK0U3NFNpOBA33sKiO4W87XjaYaOH/SxUavLCNnMuoIU0X1GsW48M' +
+  'ij1Zla1R2qoxNIEOPN1ai/PHxPRJLOU+Q5b/U3UmMvEzu/Wa+dR/wTlsiI/PrRZVtBO37AbA' +
+  'LAn9gl2Od8/g6YP4R6ZBwh0iukWEy2D7EwAV+GAZaOu0/dyX7zeUTASYefD2a1KtXfcYAB9i' +
+  '5n4A7mCL9vs+r2CSHqfMXtdbybeCpD1XpMwu8S8D9CB5Mq0sOU6KvxKR3cgd9mznQLKWM6pt' +
+  'LLfR9/xBVjQkjtOIen0ZnPeLx0/iy8eEqaN3Jc3Fx92j2BeMTK6lW6ykw/jZ4p3C/KHJM/kG' +
+  'x/L9bwwux1PuCGk6kGhwzgc3ax2Vuy3Lvwaev0/UO5vaUrmYECcCP14TP1lX1BdPe0OIafJ9' +
+  'e/XpRv4r8MfH3BbU4XFTLdUSsUcCh5GnG+hviCwAM0aHrDUyWCE9A2d2IT5w0wJeFaMBulFG' +
+  'DbayY721nC8nlNqjSHod0atUzo761vxytuzvoN+L/bv43sOaiqcty0uBmklQ15mIOucMOkbD' +
+  'ncrzElrTGJuSy1R6XbA/Syw9YjsJdt0TLOo8kjbB7ifq7OfzSb7XrC37EubMdYyBd+GzcIkh' +
+  'xG0lx9pHOa8NFXQQ9veqpuyufLVAofar82t8sV9CQzyGRqkSpZIW6Ytacxca+TVluV9ridxQ' +
+  'nF3ha/U4C79qKTnikdrIWu9B52ZQbWcVe29+sKb4qsFcBDeKWfF09kES1S8svaTVejDeiNts' +
+  'QOgUzsshb+IPrcSwugjuRzFnRnD753ySp5N1kdHbKLd/CzoUN9qM+j3XFy0yz84vVNQJIn3P' +
+  'TNRpXZZ2k5r4t756Z1/gR7eucoi2QF8CXjBbkLgSN7keJBo5U2J3YmhVLEt7F9Ct982W2IfD' +
+  'fhOPjq1YYoNSAA7O0ckyFw789AGeA4HDoKca9uG8Hgow8eAXD166CsANj4hqDsJax6UStHwG' +
+  'fb1datcBYgNoGDD2IIY1NePFY4EeyII/tGNKSt1ZbwQz5lst5LPILtz6HZRWz9FH2Fso3UP4' +
+  'yAto+y8w+y3MlM2grrngRcFXwrJjXMpdcnexUnPzRdaZ/mr+J+w3592Tcldxzn9CtC7xtfN5' +
+  'uP2D2H8BsGL5W7blULYAAAAASUVORK5CYII=';
+// cspell:enable
 
-  _waitFor = (condition: any, timeout: any, callback: any) => {
-    let remaining = timeout;
-    const timeoutFunction = function () {
-      if (condition()) {
-        callback(true);
-        return;
-      }
-      remaining--;
-      if (remaining === 0) {
-        callback(false);
-      } else {
-        setTimeout(timeoutFunction, 1000);
-      }
-    };
-    setTimeout(timeoutFunction, 1000);
-  };
+const xhr = new XMLHttpRequest();
+xhr.responseType = 'blob';
 
-  componentDidMount() {
-    this._get();
-    this._waitFor(this._getSucceeded, 6, doneSucceeded => {
-      let reader = new FileReader();
-      reader.readAsDataURL(this.state.xhr.response);
-      reader.onload = () => {
-        TestModule.markTestPassed(
-          doneSucceeded && this.state.expected === reader.result,
-        );
-      };
-    });
+xhr.onloadend = () => {
+  const succeeded = xhr.status === 200 && xhr.response !== null;
+  if (!succeeded) {
+    TestModule.markTestPassed(false);
+    return;
   }
 
-  render(): React.Node {
-    return <View />;
-  }
-}
+  const reader = new FileReader();
+  reader.onload = () => {
+    TestModule.markTestPassed(reader.result === EXPECTED_DATA_URL);
+  };
+  reader.onerror = () => {
+    TestModule.markTestPassed(false);
+  };
+  reader.readAsDataURL(xhr.response);
+};
 
-AppRegistry.registerComponent('BlobTest', () => BlobTest);
+xhr.onerror = () => {
+  TestModule.markTestPassed(false);
+};
 
-module.exports = BlobTest;
+xhr.open('GET', URL);
+xhr.setRequestHeader('Accept-Encoding', 'utf-8');
+xhr.send();

From 3e92545ca610c4fef48040cc1923ef843836461f Mon Sep 17 00:00:00 2001
From: Julio Cesar Rocha <julio.rocha@microsoft.com>
Date: Mon, 8 Jun 2026 00:37:54 -0700
Subject: [PATCH 10/15] WebSocketMultipleSendTest

---
 .../RNTesterHeadlessTests.cpp                 |   4 +
 .../WebSocketMultipleSendTest.js              | 199 +++++++-----------
 2 files changed, 84 insertions(+), 119 deletions(-)

diff --git a/vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp b/vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp
index 7a293454f94..67cb12d5ca6 100644
--- a/vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp
+++ b/vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp
@@ -92,6 +92,10 @@ TEST_CLASS (RNTesterHeadlessTests) {
     RunTest(L"IntegrationTests/WebSocketArrayBufferTest");
   }
 
+  TEST_METHOD(WebSocketMultipleSend) {
+    RunTest(L"IntegrationTests/WebSocketMultipleSendTest");
+  }
+
   TEST_METHOD(Blob) {
     RunTest(L"IntegrationTests/BlobTest");
   }
diff --git a/vnext/src-win/IntegrationTests/WebSocketMultipleSendTest.js b/vnext/src-win/IntegrationTests/WebSocketMultipleSendTest.js
index e3658cdab96..afaa789368f 100644
--- a/vnext/src-win/IntegrationTests/WebSocketMultipleSendTest.js
+++ b/vnext/src-win/IntegrationTests/WebSocketMultipleSendTest.js
@@ -10,7 +10,6 @@
  * LICENSE file in the root directory of this source tree.
  *
  * @format
- * @flow
  */
 
 /*
@@ -25,10 +24,13 @@ Array.from('abcdef').forEach( e => { ws.send(e.repeat(1025)) });
 
 'use strict';
 
-const React = require('react');
-const ReactNative = require('react-native');
-const {AppRegistry, View} = ReactNative;
-const {TestModule} = ReactNative.NativeModules;
+const {TurboModuleRegistry} = require('react-native');
+
+const TestModule = TurboModuleRegistry.get('TestModule');
+
+if (!TestModule) {
+  throw new Error('TestModule is not available');
+}
 
 // eslint-disable-next-line @microsoft/sdl/no-insecure-url
 const URL_BASE = 'ws://localhost:5555/rnw/rntester/websocketmultiplesendtest';
@@ -41,131 +43,90 @@ const EXPECTED = 'abcdef';
 
 const ID = Math.floor(Math.random() * 1000000);
 
-type State = {
-  sendUrl: string,
-  receiveUrl: string,
-  sendSocket: ?WebSocket,
-  receiveSocket: ?WebSocket,
-  result: ?string,
-};
-
-class WebSocketMultipleSendTest extends React.Component<{}, State> {
-  state: State = {
-    sendUrl: `${URL_BASE}/send/${ID}`,
-    receiveUrl: `${URL_BASE}/receive/${ID}`,
-    sendSocket: null,
-    receiveSocket: null,
-    result: '',
-  };
+const sendUrl = `${URL_BASE}/send/${ID}`;
+const receiveUrl = `${URL_BASE}/receive/${ID}`;
 
-  _waitFor = (condition: any, timeout: any, callback: any) => {
-    let remaining = timeout;
-    const timeoutFunction = function () {
-      if (condition()) {
-        callback(true);
-        return;
-      }
-      remaining--;
-      if (remaining === 0) {
-        callback(false);
-      } else {
-        setTimeout(timeoutFunction, 1000);
-      }
-    };
-    setTimeout(timeoutFunction, 1000);
-  };
+let sendSocket = null;
+let receiveSocket = null;
+let result = '';
 
-  _socketsAreConnected = (): boolean => {
-    return (
-      this.state.sendSocket?.readyState === 1 &&
-      this.state.sendSocket?.readyState === 1
-    ); // OPEN
+const waitFor = (condition, timeout, callback) => {
+  let remaining = timeout;
+  const timeoutFunction = function () {
+    if (condition()) {
+      callback(true);
+      return;
+    }
+    remaining--;
+    if (remaining === 0) {
+      callback(false);
+    } else {
+      setTimeout(timeoutFunction, 1000);
+    }
   };
+  setTimeout(timeoutFunction, 1000);
+};
 
-  _socketsAreDisconnected = (): boolean => {
-    return (
-      this.state.sendSocket?.readyState === 3 &&
-      this.state.sendSocket?.readyState === 3
-    ); // CLOSED
-  };
+const socketsAreConnected = () => {
+  return sendSocket?.readyState === 1 && sendSocket?.readyState === 1; // OPEN
+};
 
-  _resultIsComplete = (): boolean => {
-    return this.state.result === EXPECTED;
-  };
+const socketsAreDisconnected = () => {
+  return sendSocket?.readyState === 3 && sendSocket?.readyState === 3; // CLOSED
+};
 
-  _disconnect = () => {
-    if (this.state.receiveSocket) {
-      this.state.receiveSocket.close();
-    }
-  };
+const resultIsComplete = () => {
+  return result === EXPECTED;
+};
 
-  testDisconnect: () => void = () => {
-    this._disconnect();
-    this._waitFor(this._socketsAreDisconnected, 5, disconnectSucceeded => {
-      TestModule.markTestPassed(disconnectSucceeded);
-    });
-  };
+const disconnect = () => {
+  if (receiveSocket) {
+    receiveSocket.close();
+  }
+};
 
-  testSendMultipleAndClose: () => void = () => {
-    this.state.sendSocket?.send('a'.repeat(MESSAGE_SIZE));
-    this.state.sendSocket?.send('b'.repeat(MESSAGE_SIZE));
-    this.state.sendSocket?.send('c'.repeat(MESSAGE_SIZE));
-    this.state.sendSocket?.send('d'.repeat(MESSAGE_SIZE));
-    this.state.sendSocket?.send('e'.repeat(MESSAGE_SIZE));
-    this.state.sendSocket?.send('f'.repeat(MESSAGE_SIZE));
-    this.state.sendSocket?.close();
-
-    this._waitFor(this._resultIsComplete, 5, resultComplete => {
-      if (!resultComplete) {
-        TestModule.markTestPassed(false);
-        return;
-      }
-      this.testDisconnect();
-    });
-  };
+const testDisconnect = () => {
+  disconnect();
+  waitFor(socketsAreDisconnected, 5, disconnectSucceeded => {
+    TestModule.markTestPassed(disconnectSucceeded);
+  });
+};
 
-  _onSocketEvent = (event: any) => {
-    if (event.type === 'message' && event.data.length) {
-      var message = this.state.result + event.data[0];
-      this.setState({
-        result: message,
-      });
+const testSendMultipleAndClose = () => {
+  sendSocket?.send('a'.repeat(MESSAGE_SIZE));
+  sendSocket?.send('b'.repeat(MESSAGE_SIZE));
+  sendSocket?.send('c'.repeat(MESSAGE_SIZE));
+  sendSocket?.send('d'.repeat(MESSAGE_SIZE));
+  sendSocket?.send('e'.repeat(MESSAGE_SIZE));
+  sendSocket?.send('f'.repeat(MESSAGE_SIZE));
+  sendSocket?.close();
+
+  waitFor(resultIsComplete, 5, resultComplete => {
+    if (!resultComplete) {
+      TestModule.markTestPassed(false);
+      return;
     }
-  };
-
-  _connect = () => {
-    const sendSocket = new WebSocket(this.state.sendUrl);
-    const receiveSocket = new WebSocket(this.state.receiveUrl);
-    WS_EVENTS.forEach(ev =>
-      receiveSocket.addEventListener(ev, this._onSocketEvent),
-    );
-    this.setState({
-      sendSocket,
-      receiveSocket,
-    });
-  };
-
-  componentDidMount() {
-    this._connect();
-    this._waitFor(this._socketsAreConnected, 5, connectSucceeded => {
-      if (!connectSucceeded) {
-        TestModule.markTestPassed(false);
-        return;
-      }
-      this.testSendMultipleAndClose();
-    });
-  }
+    testDisconnect();
+  });
+};
 
-  render(): React.Node {
-    return <View />;
+const onSocketEvent = event => {
+  if (event.type === 'message' && event.data.length) {
+    result += event.data[0];
   }
-} // class WebSocketMultipleSendTest
-
-WebSocketMultipleSendTest.displayName = 'WebSocketMultipleSendTest';
+};
 
-AppRegistry.registerComponent(
-  'WebSocketMultipleSendTest',
-  () => WebSocketMultipleSendTest,
-);
+const connect = () => {
+  sendSocket = new WebSocket(sendUrl);
+  receiveSocket = new WebSocket(receiveUrl);
+  WS_EVENTS.forEach(ev => receiveSocket.addEventListener(ev, onSocketEvent));
+};
 
-module.exports = WebSocketMultipleSendTest;
+connect();
+waitFor(socketsAreConnected, 5, connectSucceeded => {
+  if (!connectSucceeded) {
+    TestModule.markTestPassed(false);
+    return;
+  }
+  testSendMultipleAndClose();
+});

From 37ca0eea94887d59951c96f14f7ffe773fd5b74b Mon Sep 17 00:00:00 2001
From: Julio Cesar Rocha <julio.rocha@microsoft.com>
Date: Mon, 8 Jun 2026 00:48:08 -0700
Subject: [PATCH 11/15] Remove JS WebSocket servers

---
 vnext/overrides.json                          |  8 -----
 ...ebsocket_integration_test_server_binary.js | 33 -------------------
 .../websocket_integration_test_server_blob.js | 33 -------------------
 3 files changed, 74 deletions(-)
 delete mode 100644 vnext/src-win/IntegrationTests/websocket_integration_test_server_binary.js
 delete mode 100644 vnext/src-win/IntegrationTests/websocket_integration_test_server_blob.js

diff --git a/vnext/overrides.json b/vnext/overrides.json
index 5425d85d586..9e17cd794ed 100644
--- a/vnext/overrides.json
+++ b/vnext/overrides.json
@@ -248,14 +248,6 @@
       "type": "platform",
       "file": "src-win/IntegrationTests/LoggingTest.js"
     },
-    {
-      "type": "platform",
-      "file": "src-win/IntegrationTests/websocket_integration_test_server_binary.js"
-    },
-    {
-      "type": "platform",
-      "file": "src-win/IntegrationTests/websocket_integration_test_server_blob.js"
-    },
     {
       "type": "platform",
       "file": "src-win/IntegrationTests/WebSocketArrayBufferTest.js"
diff --git a/vnext/src-win/IntegrationTests/websocket_integration_test_server_binary.js b/vnext/src-win/IntegrationTests/websocket_integration_test_server_binary.js
deleted file mode 100644
index 54583577d48..00000000000
--- a/vnext/src-win/IntegrationTests/websocket_integration_test_server_binary.js
+++ /dev/null
@@ -1,33 +0,0 @@
-#!/usr/bin/env node
-/**
- * Copyright (c) Meta Platforms, Inc. and affiliates.
- *
- * This source code is licensed under the MIT license found in the
- * LICENSE file in the root directory of this source tree.
- *
- * @flow
- * @format
- */
-
-'use strict';
-
-/* eslint-env node */
-
-const WebSocket = require('ws');
-
-console.log(`\
-WebSocket binary integration test server
-
-This will send each incoming message back, in binary form.
-
-`);
-
-const server = new WebSocket.Server({port: 5557});
-server.on('connection', ws => {
-  ws.binaryType = 'arraybuffer';
-  ws.on('message', message => {
-    console.log(message);
-
-    ws.send(new Uint8Array([4, 5, 6, 7]).buffer);
-  });
-});
diff --git a/vnext/src-win/IntegrationTests/websocket_integration_test_server_blob.js b/vnext/src-win/IntegrationTests/websocket_integration_test_server_blob.js
deleted file mode 100644
index d08ae16e0c5..00000000000
--- a/vnext/src-win/IntegrationTests/websocket_integration_test_server_blob.js
+++ /dev/null
@@ -1,33 +0,0 @@
-#!/usr/bin/env node
-/**
- * Copyright (c) Meta Platforms, Inc. and affiliates.
- *
- * This source code is licensed under the MIT license found in the
- * LICENSE file in the root directory of this source tree.
- *
- * @flow
- * @format
- */
-
-'use strict';
-
-/* eslint-env node */
-
-const WebSocket = require('ws');
-
-console.log(`\
-WebSocket binary integration test server
-
-This will send each incoming message back, in binary form.
-
-`);
-
-const server = new WebSocket.Server({port: 5557});
-server.on('connection', ws => {
-  ws.binaryType = 'blob';
-  ws.on('message', message => {
-    console.log(message);
-
-    ws.send([4, 5, 6, 7]);
-  });
-});

From 0445f34a07d0d036d47ceca3e523488c7a10fb37 Mon Sep 17 00:00:00 2001
From: Julio Cesar Rocha <julio.rocha@microsoft.com>
Date: Mon, 8 Jun 2026 00:50:42 -0700
Subject: [PATCH 12/15] Skip in CI for now

---
 .ado/build-template.yml | 1 +
 1 file changed, 1 insertion(+)

diff --git a/.ado/build-template.yml b/.ado/build-template.yml
index a49d68b64aa..52a2ada03a9 100644
--- a/.ado/build-template.yml
+++ b/.ado/build-template.yml
@@ -281,6 +281,7 @@ extends:
               #12714 - Disable for first deployment of test website.
               - name: Desktop.IntegrationTests.Filter
                 value: >
+                  (FullyQualifiedName!=Microsoft::React::Test::RNTesterHeadlessTests)&
                   (FullyQualifiedName!=Microsoft::React::Test::WebSocketIntegrationTest::ConnectClose)&
                   (FullyQualifiedName!=Microsoft::React::Test::WebSocketIntegrationTest::ConnectNoClose)&
                   (FullyQualifiedName!=Microsoft::React::Test::WebSocketIntegrationTest::SendReceiveClose)&

From 551993fcbd11a20c49ca060f3a1e983ee040f3da Mon Sep 17 00:00:00 2001
From: Julio Cesar Rocha <julio.rocha@microsoft.com>
Date: Mon, 8 Jun 2026 00:59:36 -0700
Subject: [PATCH 13/15] Drop LF

---
 vnext/overrides.json | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/vnext/overrides.json b/vnext/overrides.json
index 9e17cd794ed..e471e0c740f 100644
--- a/vnext/overrides.json
+++ b/vnext/overrides.json
@@ -723,4 +723,4 @@
       "baseHash": "365c5df75b38b129d364af3f6700cb206ce5bd2a"
     }
   ]
-}
+}
\ No newline at end of file

From b0ffad9cababfe31811e9001619e776261f7ad8a Mon Sep 17 00:00:00 2001
From: "Julio C. Rocha" <julio.rocha@microsoft.com>
Date: Mon, 8 Jun 2026 14:37:11 -0700
Subject: [PATCH 14/15] Drop option `WebSocket.ResourceV2`

---
 vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp | 2 --
 1 file changed, 2 deletions(-)

diff --git a/vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp b/vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp
index 67cb12d5ca6..c819059c280 100644
--- a/vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp
+++ b/vnext/Desktop.IntegrationTests/RNTesterHeadlessTests.cpp
@@ -60,8 +60,6 @@ TEST_CLASS (RNTesterHeadlessTests) {
             MddBootstrapInitializeOptions::MddBootstrapInitializeOptions_None))) {
       throw std::exception("Could not initialize Windows App runtime");
     }
-
-    SetRuntimeOptionBool("WebSocket.ResourceV2", true);
   }
 
   TEST_CLASS_CLEANUP(Cleanup) {

From 2cbb38831c86d4d21d50f734d9bcbda6b6739636 Mon Sep 17 00:00:00 2001
From: "Julio C. Rocha" <julio.rocha@microsoft.com>
Date: Mon, 8 Jun 2026 16:09:35 -0700
Subject: [PATCH 15/15] Make filter match instead of equality

---
 .ado/build-template.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.ado/build-template.yml b/.ado/build-template.yml
index 52a2ada03a9..f328ee6760c 100644
--- a/.ado/build-template.yml
+++ b/.ado/build-template.yml
@@ -281,7 +281,7 @@ extends:
               #12714 - Disable for first deployment of test website.
               - name: Desktop.IntegrationTests.Filter
                 value: >
-                  (FullyQualifiedName!=Microsoft::React::Test::RNTesterHeadlessTests)&
+                  (FullyQualifiedName!~Microsoft::React::Test::RNTesterHeadlessTests)&
                   (FullyQualifiedName!=Microsoft::React::Test::WebSocketIntegrationTest::ConnectClose)&
                   (FullyQualifiedName!=Microsoft::React::Test::WebSocketIntegrationTest::ConnectNoClose)&
                   (FullyQualifiedName!=Microsoft::React::Test::WebSocketIntegrationTest::SendReceiveClose)&