fixup! TF-4224 Reduce ReDoS vulnerability

core/test/utils/redos_vulnerability_test.dart

@@ -33,14 +33,26 @@ void main() {
       });
 
       test('should handle style with many nested parentheses', () {
+        // Primary purpose: Verify that processing malformed input with many nested
+        // parentheses doesn't cause catastrophic backtracking (ReDoS vulnerability).
+        // This pattern would freeze the old unbounded regex.
+        //
+        // Note: The current implementation is permissive - it extracts the URL content
+        // even with malformed nesting. This is acceptable for a parser that prioritizes
+        // resilience over strict validation.
         final style = 'background-image: url(${'(' * 1000}example.jpg${')' * 1000})';
 
         final stopwatch = Stopwatch()..start();
         final result = transformer.findImageUrlFromStyleTag(style);
         stopwatch.stop();
 
-        expect(stopwatch.elapsedMilliseconds, lessThan(100));
-        expect(result, isNotNull);
+        // Performance: Should complete quickly without catastrophic backtracking
+        expect(stopwatch.elapsedMilliseconds, lessThan(100),
+            reason: 'Should process quickly despite nested parentheses');
+
+        // Functional: Current implementation extracts URL despite malformed nesting
+        expect(result, isNotNull,
+            reason: 'Parser is permissive and extracts URL from malformed input');
       });
 
       test('should reject malformed background-image patterns quickly', () {
@@ -395,6 +407,7 @@ void main() {
 
         final stopwatch2 = Stopwatch()..start();
         final plainText2 = HtmlUtils.extractPlainText(extremeNesting);
+        final linked2 = HtmlUtils.wrapPlainTextLinks(extremeNesting);
         stopwatch2.stop();
 
         // Performance checks
@@ -407,6 +420,10 @@ void main() {
         expect(plainText1, contains('Deep content'));
         expect(linked1, contains('<a href='));
         expect(plainText2, contains('Content'));
+
+        // Verify extreme nesting doesn't break link wrapping
+        expect(linked2, isNotNull,
+            reason: 'Link wrapping should handle extreme nesting without crashing');
       });
     });