Review Rust changes for correctness, memory and thread safety, error semantics, unnecessary allocation or cloning, lock scope, API compatibility, test gaps, documentation, and dependency risk, applying the Rust API Guidelines checklist (C-PANIC, C-UNWRAP, C-TRANSMUTE, C-BOOL, C-NEWTYPE, C-COMMON-TRAITS, C-CONVERT, C-SEALED, C-NON-EXHAUSTIVE).
