April 2026 monthly summary for facebook/folly. Focused on strengthening correctness and stability of ROAR-based symbolization under AArch64 address permissions. Delivered a targeted bug fix to ensure the symbolization step correctly assesses executability when the loader changes address permissions on AArch64, reducing false positives/negatives in ROAR symbolization and improving reliability for security analyses.

March 2026 highlights across Sapling, Buck2, and Buck2-Prelude: - Sapling: Fixed a crash in the Logging System when processing empty-tree commits by filtering out null IDs during object fetches, improving repository reliability. Commit: 98a9881410b97211c6187853b173da2a2ba0f18a. Reviewed by: quark-zju. Differential Revision: D95641171. - Buck2: Implemented cross-compilation support by embedding the runtime library into the target application and extending the cxx_toolchain_override with a runtime resource directory, enabling proper linking and addressing circular dependencies in toolchain specifications. Commit: f7631cd36f95508d022484c4e258ea11dd5be2ee. Reviews: skrueger, jpporto. Differential Revision: D97827958. - Buck2-Prelude: Added cross-compilation runtime embedding for the buckified 19roar toolchain by embedding the runtime library into the target application, via a resource directory in the cxx_toolchain_override. Commit: a869ba56c99a329eaca48b78a232cc3667f7baf3. Reviews: skrueger, jpporto. Differential Revision: D97827958. - Cross-repo alignment: Standardized the runtime embedding approach across Buck2 and Buck2-Prelude to improve linking reliability and platform coverage. - Overall impact: Enhanced stability and cross-platform build capabilities, reducing integration risk, accelerating feature delivery, and strengthening the toolchain architecture.

December 2025 monthly summary focused on stabilizing Python extensions builds in Buck2 by enabling and propagating the content-based paths flag through the C++ toolchain, across Buck2 and Buck2 Prelude. Key outcomes include enabling supports_content_based_paths to fix a Python extensions build error when using buckified LLVM toolchain, and forwarding the base toolchain's value to overridden CxxRuleConstructorParams to avoid None-related failures. This work reduces build-time failures and supports reliable Python extension builds across repositories.

November 2025: Focused on stabilizing configuration handling in Buck2 and its Prelude. Delivered critical backouts that remove recursion risks and preserve simple references to constraint_values, ensuring reliable tooling and buck graph operations. Result: increased stability for configuration resolution, reduced maintenance burden for downstream tooling, and clearer upgrade path for future configuration changes.