fix: resolve UTF-8 string parsing ''String too short'' error in PHP serializer

- Fix string parsing logic to properly handle UTF-8 byte-to-character conversion
- Update unserializeValue() to count actual UTF-8 bytes using TextEncoder
- Add comprehensive test case for the exact problematic serialized string
- Ensures PHP''s byte-length-based serialization format works with multi-byte characters

Fixes issue where complex serialized strings with UTF-8 characters like ''测试 café 🚀''
would fail with ''String too short'' error during unserialization.

Co-authored-by: Nadim Tuhin <nadimtuhin@users.noreply.github.com>

Author: claude[bot]

src/components/PhpSerializer.test.tsx

@@ -482,5 +482,32 @@ describe('PhpSerializer', () => {
       expect(phpOutput.value).toContain('s:2:"id";i:123');
       expect(phpOutput.value).toContain('s:4:"name";s:8:"John Doe"');
     });
+
+    test('handles UTF-8 strings in complex serialized data without "String too short" error', () => {
+      const phpInput = screen.getAllByRole('textbox')[0];
+      const phpOutput = screen.getAllByRole('textbox')[1];
+      
+      // The exact serialized string that was causing the "String too short" error
+      const problematicSerializedString = `a:5:{s:4:"user";O:4:"User":1:{s:1:"0";a:8:{s:2:"id";i:123;s:4:"name";s:8:"John Doe";s:5:"email";s:16:"john@example.com";s:6:"active";b:1;s:7:"balance";d:99.99;s:11:"preferences";N;s:4:"tags";a:2:{i:0;s:9:"developer";i:1;s:5:"admin";}s:8:"metadata";a:3:{s:10:"created_at";s:10:"2024-01-15";s:10:"last_login";s:10:"2024-07-16";s:11:"login_count";i:42;}}}s:8:"settings";a:3:{s:5:"theme";s:4:"dark";s:13:"notifications";b:1;s:8:"language";s:5:"en-US";}s:5:"items";a:3:{i:0;s:5:"item1";i:1;s:5:"item2";i:2;s:5:"item3";}s:15:"special_numbers";a:3:{s:8:"infinity";d:INF;s:17:"negative_infinity";d:-INF;s:12:"not_a_number";d:NAN;}s:9:"utf8_test";s:17:"测试 café 🚀";}`;
+      
+      // This should not throw "String too short" error anymore
+      fireEvent.change(phpOutput, { target: { value: problematicSerializedString } });
+      
+      // Verify no error is displayed
+      expect(screen.queryByText(/Error:/)).not.toBeInTheDocument();
+      expect(screen.queryByText(/String too short/)).not.toBeInTheDocument();
+      
+      // Verify the UTF-8 string is correctly parsed
+      expect(phpInput.value).toContain("'utf8_test' => '测试 café 🚀'");
+      
+      // Verify other complex elements are parsed correctly
+      expect(phpInput.value).toContain('new User([');
+      expect(phpInput.value).toContain("'name' => 'John Doe'");
+      expect(phpInput.value).toContain("'email' => 'john@example.com'");
+      expect(phpInput.value).toContain("'special_numbers' => [");
+      expect(phpInput.value).toContain("'infinity' => INF");
+      expect(phpInput.value).toContain("'negative_infinity' => -INF");
+      expect(phpInput.value).toContain("'not_a_number' => NAN");
+    });
   });
 });

src/components/PhpSerializer.tsx

@@ -416,11 +416,36 @@ const PhpSerializer = () => {
       if (colonPos === -1) throw new Error('Invalid string format');
       const lengthStr = input.slice(2, colonPos);
       if (!/^\d+$/.test(lengthStr)) throw new Error('Invalid string length');
-      const length = parseInt(lengthStr, 10);
+      const byteLength = parseInt(lengthStr, 10);
 
       if (input[colonPos + 1] !== '"') throw new Error('String must start with quote');
       const startPos = colonPos + 2;
-      const endPos = startPos + length;
+      
+      // Find the actual end position by counting bytes, not characters
+      // Since JavaScript strings are UTF-16, we need to convert to bytes and count
+      const remainingInput = input.slice(startPos);
+      const encoder = new TextEncoder();
+      let charIndex = 0;
+      let currentByteLength = 0;
+      
+      // Find where we reach the target byte length
+      while (currentByteLength < byteLength && charIndex < remainingInput.length) {
+        const char = remainingInput[charIndex];
+        const charBytes = encoder.encode(char).length;
+        if (currentByteLength + charBytes <= byteLength) {
+          currentByteLength += charBytes;
+          charIndex++;
+        } else {
+          break;
+        }
+      }
+      
+      // Check if we have the exact byte length
+      if (currentByteLength !== byteLength) {
+        throw new Error('String byte length mismatch');
+      }
+      
+      const endPos = startPos + charIndex;
 
       if (input.length < endPos + 2) throw new Error('String too short');
       if (input[endPos] !== '"' || input[endPos + 1] !== ';') {