Worked on the apache/pulsar repository to enhance backend reliability by focusing on test suite stabilization and robust error handling. Addressed two critical bugs by refining the asynchronous ledger opening logic in ManagedCursorTest, ensuring accurate error propagation during recovery scenarios. Improved test reliability for multi-topic and Dead Letter Topic cases by adjusting receiver queue sizing to better reflect buffer limitations, thereby reducing test flakiness. These efforts, implemented in Java with a strong emphasis on backend development and testing, contributed to lowering release risk and increasing developer confidence in Pulsar’s recovery paths and test harness, even though no new features were delivered.