PHP's `declare(strict_types=1)` directive is a powerful tool for preventing subtle bugs. Yet most existing, mature projects don't use it consistently, if at all. Why? Because automatically adding it to all your files at once will cause your application to explode: expect thousands of errors. That leaves you fixing files by hand, one by one, and relying on team members to remember to add it to new files. Without a safe and automated process, adoption hardly ever sticks. Until now. The new `SafeDeclareStrictTypesRector` only adds strict types to files that are **already type-safe**, making safe, progressive adoption finally possible and preventing the file from becoming non-strict in the future.