Worked on stabilizing the PDF download functionality in the hmcts/em-media-viewer repository, focusing on the PdfJsWrapper component. Addressed a persistent bug by aligning the downloadFile method with the downloadManager API, carefully evaluating both download and downloadUrl integration paths to reduce instability. Adjusted and expanded unit tests in TypeScript to guard against regressions, ensuring that changes were traceable and reversible as the correct API direction was determined. The work emphasized front-end development best practices, improved reliability for end users, and established documentation to support future iterations, laying a foundation for consistent PDF download behavior across different environments and deployments.