Worked on the oppia-android repository to enhance reliability and test coverage for core profile management and asynchronous result handling features. Focused on strengthening the deleteAllProfiles functionality by implementing targeted unit tests in Kotlin, ensuring that only user profiles are deleted while preserving non-profile data and maintaining cache consistency across app restarts. Additionally, developed comprehensive tests for the AsyncResultSubject class, covering edge cases such as type mismatches and deep failure-chain checks. Validated all changes with Bazel and static analysis tools, contributing to safer future refactors. Demonstrated a methodical approach to Android development, emphasizing robust unit testing and regression prevention.