function syncStringsByTag(str1: string, str2: string, tag: string): [string, string] {

  // Split strings into lines

  let lines1 = str1.split('\n');

  let lines2 = str2.split('\n');

​

  // Determine the maximum number of lines needed

  const maxLength = Math.max(lines1.length, lines2.length);

​

  // Initialize empty lines where necessary

  lines1 = lines1.concat(Array(maxLength - lines1.length).fill(''));

  lines2 = lines2.concat(Array(maxLength - lines2.length).fill(''));

​

  // Ensure <t> tags align

  for (let i = 0; i < maxLength; i++) {

    const hasTag1 = lines1[i].includes(tag);

    const hasTag2 = lines2[i].includes(tag);

​

    if (hasTag1 && !hasTag2) {

      lines2.splice(i, 0, '');

      lines1 = lines1.concat('');

    } else if (!hasTag1 && hasTag2) {

      lines1.splice(i, 0, '');

      lines2 = lines2.concat('');

    }

  }

​

  // Join the lines back into single strings

  const syncedStr1 = lines1.join('\n');

  const syncedStr2 = lines2.join('\n');

​

  return [syncedStr1, syncedStr2];

}

​

// Example usage

const str1 = "Line 1\nLine 2\n<t>Tag 1</t>\nLine 4";

const str2 = "First Line\n<t>Tag 2</t>\nThird Line\nFourth Line";

​

const [syncedStr1, syncedStr2] = syncStringsByTag(str1, str2, '<t>');

​

console.log('Synced String 1:\n', syncedStr1);

console.log('Synced String 2:\n', syncedStr2);

​