How to ensure painless script does not cause recompilation?

Question

I am using a script in sort context to achieve custom sorting. The following is my script sort node that allows custom sorting.

{
  "_script": {
    "type": "string",
    "script": {
      "source": """
            
                   def sortingValue = "";
        for(query in params.queries) {
              if (doc['firstName.keyword'].size() > 0 && doc['firstName.keyword'].value.startsWith(query)) {
                   sortingValue = '1' +":"+ doc['fullName.keyword'].value;
                   break;
               } else if (doc['lastName.keyword'].size() > 0 && doc['lastName.keyword'].value.startsWith(query)) {
                   sortingValue = '2' +":"+ doc['fullName.keyword'].value;
                   break;
                } else if (doc['companyName.keyword'].size() > 0 && doc['companyName.keyword'].value.contains(query)) {
                   sortingValue = '3' + ":" + doc['companyName.keyword'].value;
                   break;
                } else {
                   sortingValue = '4';
                }
        }
        return sortingValue;
                """,
      "params": {
        "queries": [
          "mo",
          "buga"
        ]
      }
    },
    "order": "asc"
  }
}

With the script i categorise the result sorted in following way

Search Text: Mo Buga

Category 1: Sort contacts with first name starting with Mo or Buga at the top

Category 2: Sort contacts with last name starting with Mo or Buga at the second category

Category 3: Sort contacts with company name starting with Mo or Buga at the third category

Category 4: Every other matching result in category four

How do i ensure there are no unwanted recompilations.