A product owner is responsible for a new product.

In Agile, ensuring that the product works without bugs or missing features can be achieved through continuous testing and validation of the product. Test-driven development (TDD) is an approach where tests are written before the code is developed. This helps ensure that each feature is fully tested as it is built, focusing on customer requirements from the start and preventing issues from accumulating. By using TDD, the product owner ensures the product is being tested incrementally, which reduces the risk of defects and aligns with customer expectations for a high-quality product upon release.