The developer is asked to enhance the functionality of an existing controller route by adding...

In Salesforce Commerce Cloud's Storefront Reference Architecture (SFRA), the recommended way to enhance the functionality of an existing controller route without altering the original code is to use the "extend" method provided by the server module. This method allows developers to extend an existing route and add or modify its functionality by adding additional processing or modifying viewData. This approach keeps the base controller intact and ensures that the customization is isolated, which simplifies updates and maintenance. By using "extend", the original route remains unchanged, and new functionality is layered on top of it, which aligns with best practices for modularity and maintainability in software development.