June 2026 monthly summary: Implemented cross-repo umbrella header generation controls for Buck2 and Buck2 Prelude to improve build flexibility and reduce build times in mixed-language projects. Introduced a new disable_generated_umbrella_header flag for opt-out umbrella header generation and applied it consistently across all Buck builds. Result: more predictable module behavior for Objective-C/Swift interop and simplified header management across repositories.

April 2026 — Delivered automated umbrella header generation for mixed ObjC/Swift Buck2 modules across buck2-prelude and buck2, reducing manual steps and preventing build failures during ObjC-to-Swift migrations. The changes auto-generate the umbrella header when missing and add it to both exported and internal preprocessor information to ensure robust header resolution for downstream and same-module consumers. This work enhances migration velocity, build reliability, and developer productivity by eliminating a common manual step during ObjC-to-Swift migrations.

April 2025 monthly summary for facebook/react-native focused on establishing code-style standardization groundwork and preparing for automated enforcement of the swift-format OrderedImports rule.