Rust Unsafe Boundary Audit - make every unsafe edge small, named, and tested

Use this skill when a Rust change, crate, or repository needs a focused audit of unsafe blocks, raw pointer handling, layout assumptions, or foreign-function boundaries. The goal is not to forbid unsafe code; it is to make each unsafe operation local, justified, mechanically guarded where possible, and covered by tests or tooling that exercise the contract.

Critical Constraints