Worked on enhancing Firestore’s offline-first reliability by improving integration testing across the firebase/firebase-android-sdk and firebase/firebase-js-sdk repositories. Focused on validating data synchronization and query consistency between online and offline modes, the work involved expanding test coverage, refactoring utilities, and pre-populating caches to simulate real-world scenarios. Leveraged Java and JavaScript to ensure that queries from cache, server, and remote keys produced identical results, reducing the risk of data divergence. These efforts strengthened cross-repository test coverage, enabled earlier detection of edge-case regressions, and supported faster, safer release cycles, demonstrating depth in Android development, backend testing, and performance optimization.