I have a Google Sheet that receives form responses and I need a lightweight Apps Script that steps in the moment a new row is added. The script should automatically inspect each incoming submission and stop any row that is missing required fields, alerting the user with a friendly toast pop-up or an email response so the data never reaches the main sheet incomplete. Here is what I expect: • A clean Apps Script bound to the spreadsheet, triggered on Form Submit, that checks the specific columns I identify as “required”. • Clear comments in the code so I can adjust the required-field list later without hunting through logic. • A brief hand-off note or Loom video showing how to enable the trigger, test the validation, and roll back if needed. If you have sample code or a live spreadsheet you’ve protected with similar rules, point me to it—it will speed up selection.