Worked on stabilizing and securing core user experiences in two major iOS projects, focusing on bug fixes and library management using Swift and UIKit. In the airbnb/lottie-ios repository, addressed ZIP extraction vulnerabilities by upgrading the embedded ZIPFoundation library and implementing safer error handling, which improved both security and maintainability. In mozilla-mobile/firefox-ios, resolved a pan gesture crash in the tracking protection UI by replacing force unwrapping with safe optional binding and expanded unit test coverage for key view controllers. These efforts enhanced UI reliability, reduced regression risk, and reinforced the stability of tracking protection features through targeted unit testing.