During June 2025, Zang Zhichong focused on improving metadata handling in the google/kotlin repository, specifically addressing the preservation and association of source file information within Kotlin metadata klib. He resolved an issue in KlibPropertyExtension by replacing the use of an integer file index with KlibSourceFile, ensuring that propertyFile data is accurately maintained and linked to the correct source files. This work required a deep understanding of compiler internals and Kotlin metadata structures, and was implemented using Kotlin. The fix enhanced the reliability of metadata processing, contributing to more robust source-file linkage in the Kotlin compilation pipeline.