Worked on the apache/iceberg-go repository to address a critical data integrity issue in fast-append operations, focusing on backend development and data engineering using Go. Implemented a fix to ensure all parent manifests, including those with zero-count files, are unconditionally inherited during fast-append, preventing data loss when external writers such as Athena interact with the system. Enhanced reliability by adding targeted regression tests and validating changes against the full table test suite to confirm stability. This work improved manifest handling in Iceberg v2, strengthened cross-writer data visibility, and demonstrated a thorough approach to testing and quality assurance in backend systems.