make parameter properly respects key-value pairs

engine/src/flutter/lib/web_ui/lib/src/engine/platform_dispatcher.dart

diff --git a/engine/src/flutter/lib/web_ui/lib/src/engine/platform_dispatcher.dart b/engine/src/flutter/lib/web_ui/lib/src/engine/platform_dispatcher.dart
index 8d9301c..ca5cba9 100644
--- a/engine/src/flutter/lib/web_ui/lib/src/engine/platform_dispatcher.dart
+++ b/engine/src/flutter/lib/web_ui/lib/src/engine/platform_dispatcher.dart
@@ -56,14 +56,21 @@
   }
 
   /// Checks if the given URI contains the flutter-semantics query parameter.
-  /// If present, enables semantics. This allows automation testing tools to
-  /// enable semantics without modifying the app.
+  /// If present and not explicitly set to false, enables semantics. This allows
+  /// automation testing tools to enable semantics without modifying the app.
+  ///
+  /// Accepted values:
+  /// - `?flutter-semantics` or `?flutter-semantics=true` → enables
+  /// - `?flutter-semantics=false` → does not enable
   ///
   /// This method is separated for testing purposes.
   @visibleForTesting
   void checkUriForSemanticsParameter(Uri uri) {
-    if (uri.queryParameters.containsKey('flutter-semantics')) {
-      EngineSemantics.instance.semanticsEnabled = true;
+    final String? value = uri.queryParameters['flutter-semantics'];
+    if (value != null) {
+      if (value.toLowerCase() != 'false') {
+        EngineSemantics.instance.semanticsEnabled = true;
+      }
     }
   }
 

engine/src/flutter/lib/web_ui/test/engine/platform_dispatcher/platform_dispatcher_test.dart

diff --git a/engine/src/flutter/lib/web_ui/test/engine/platform_dispatcher/platform_dispatcher_test.dart b/engine/src/flutter/lib/web_ui/test/engine/platform_dispatcher/platform_dispatcher_test.dart
index 702e962..10a07fb 100644
--- a/engine/src/flutter/lib/web_ui/test/engine/platform_dispatcher/platform_dispatcher_test.dart
+++ b/engine/src/flutter/lib/web_ui/test/engine/platform_dispatcher/platform_dispatcher_test.dart
@@ -420,6 +420,24 @@
       expect(semantics().semanticsEnabled, isTrue);
     });
 
+    test('query parameter enables semantics when set to true', () {
+      semantics().semanticsEnabled = false;
+      final Uri uriWithTrue = Uri.parse('https://example.com/?flutter-semantics=true');
+
+      dispatcher.checkUriForSemanticsParameter(uriWithTrue);
+
+      expect(semantics().semanticsEnabled, isTrue);
+    });
+
+    test('query parameter does not enable semantics when set to false', () {
+      semantics().semanticsEnabled = false;
+      final Uri uriWithFalse = Uri.parse('https://example.com/?flutter-semantics=false');
+
+      dispatcher.checkUriForSemanticsParameter(uriWithFalse);
+
+      expect(semantics().semanticsEnabled, isFalse);
+    });
+
     test('query parameter does not enable semantics when absent', () {
       semantics().semanticsEnabled = false;
       final Uri uriWithoutParameter = Uri.parse('https://example.com/');