June 2026 monthly summary focusing on reliability, compatibility, and robustness across two core repos: facebookresearch/faiss and jax-ml/jax. Delivered fixes that remove integration barriers for downstream consumers, and hardened key management for PRNG usage under vmap. The work improved build reliability with installed FAISS headers and hardened PRNG key handling in edge-case scenarios. Key features delivered: - FAISS: Added missing InvertedListScannerStats.h to the FAISS_HEADERS install list, enabling builds against installed FAISS and eliminating header-not-found failures in downstream consumers (e.g., COLMAP). Commit ab632382d3d0531fc6c744e0948544aa358bc850; PR 5268; Differential Revision: D107271556. - JAX: Strengthened PRNG key management by fixing a zero-sized key array handling under vmap, preventing spurious KeyReuseError and ensuring no-op behavior for empty masks. Commit 4603e66f1fabc669018ea314f0c179a5b042bcfc; improves robustness of key reuse checks when jax_debug_key_reuse is enabled. Major bugs fixed: - FAISS: Resolve header install gap by including impl/InvertedListScannerStats.h in FAISS_HEADERS; eliminates build failures when consuming installed FAISS. - JAX: Fix spurious KeyReuseError under vmap with zero-sized key arrays by treating empty masks as a no-op, avoiding incorrect key consumption. Overall impact and accomplishments: - Increased reliability and downstream compatibility for FAISS-powered projects by removing header install gaps and ensuring successful builds against installed libraries. - Hardened JAX PRNG key management, reducing surprising key reuse errors in vectorized mappings and improving robustness for research pipelines that rely on jax’s PRNG utilities. - Demonstrated interoperability, code-quality improvements, and responsiveness to external consumer issues and edge-case scenarios. Technologies/skills demonstrated: - C++ header packaging and build-system hygiene in FAISS; integration with public headers and install graphs. - Python/NumPy-based PRNG and vmap edge-case handling in JAX; attention to edge-case correctness and runtime robustness. - Cross-repo collaboration, issue-tracking awareness, and effective pull-request-driven fixes.