Implement AccessibilityInfo.announceForAccessibility for Fabric

change/react-native-windows-38181227-9db6-47e6-bd4b-9dcf4721c299.json

@@ -0,0 +1,7 @@
+{
+  "type": "prerelease",
+  "comment": "Implement announceForAccessibility for Fabric using Win32 UIA",
+  "packageName": "react-native-windows",
+  "email": "198982749+Copilot@users.noreply.github.com",
+  "dependentChangeType": "patch"
+}

vnext/Microsoft.ReactNative/Modules/AccessibilityInfoModule.cpp

@@ -79,6 +79,54 @@ void AccessibilityInfo::announceForAccessibility(std::wstring announcement) noex
         xaml::Automation::Peers::AutomationNotificationProcessing::ImportantMostRecent,
         hstr,
         hstr);
+#else
+    // Fabric implementation using Win32 UIA
+    if (!UiaClientsAreListening()) {
+      return;
+    }
+
+    HWND hwnd = ::GetActiveWindow();
+    if (!hwnd) {
+      return;
+    }
+
+    IRawElementProviderSimple *provider = nullptr;
+    HRESULT hrProvider = UiaHostProviderFromHwnd(hwnd, &provider);
+    if (FAILED(hrProvider) || !provider) {
+      return;
+    }
+
+    // Convert announcement string to BSTR
+    BSTR bstrAnnouncement = SysAllocString(announcement.c_str());
+    if (!bstrAnnouncement) {
+      provider->Release();
+      return;
+    }
+
+    // Create a GUID and get string form for activityId
+    GUID guid;
+    wchar_t guidString[40] = {};
+    BSTR bstrActivityId = nullptr;
+
+    if (SUCCEEDED(CoCreateGuid(&guid))) {
+      int len = StringFromGUID2(guid, guidString, ARRAYSIZE(guidString));
+      if (len > 1) {
+        bstrActivityId = SysAllocString(guidString);
+      }
+    }
+
+    if (!bstrActivityId) {
+      SysFreeString(bstrAnnouncement);
+      provider->Release();
+      return;
+    }
+
+    HRESULT hr = UiaRaiseNotificationEvent(
+        provider, NotificationKind_Other, NotificationProcessing_ImportantMostRecent, bstrAnnouncement, bstrActivityId);
+
+    SysFreeString(bstrAnnouncement);
+    SysFreeString(bstrActivityId);
+    provider->Release();
 #endif
   });
 }