Harness, a startup in the software delivery space, implemented a two-phase quality improvement strategy to address challenges related to customer-found defects (CFDs) and internally-found defects (IFDs), aiming to enhance product quality without hindering development speed. The strategy involved setting stringent feature sign-off criteria, increasing automation coverage, and focusing on both new and legacy features. Initially, the company concentrated on critical end-to-end scenarios and improving the quality of new features to avoid adding technical debt. In the second phase, attention was directed towards legacy features to improve customer experience, employing a targeted approach to yield consistent results. This quality playbook included detailed root cause analysis, enhanced test coverage, and automation efforts, ultimately achieving a significant reduction in defects and improving the overall defect detection efficiency. Harness's approach underscores the importance of maintaining quality in rapidly scaling environments while balancing the introduction of new features with the management of existing technical debt.