Josh Arnold focused on improving the build reliability of the swiftlang/sourcekit-lsp repository by addressing a complex bug in the BuildSystemManager’s dependency analysis. He identified and resolved an algorithmic flaw that caused exponential blowup during dependency resolution, implementing a fix that leverages each dependency’s recorded depth to optimize performance. Working primarily in Swift, Josh applied his skills in algorithm optimization and dependency analysis to ensure more efficient and stable builds, especially for large dependency graphs. His work demonstrated careful debugging and thoughtful engineering, resulting in a targeted solution that enhanced both the correctness and efficiency of the build system’s core logic.