Safe Rust wrapper for the Windows Host Compute Service (HCS).

HCS is the OS-level API powering Windows containers and Hyper-V-isolated workloads; the underlying surface lives in vmcompute.dll. This crate wraps those raw calls with RAII handle types, async operation helpers that translate HCS's native completion-callback model into Rust futures, and JSON schema types that match the current hcsshim schema v2.

The crate is Windows-only. On every other platform it compiles to an empty stub so callers can depend on it unconditionally.

unsafe policy

This crate is the authoritative Windows HCS FFI boundary for ZLayer. It exists specifically to wrap the unsafe vmcompute.dll entry points behind safe, typed Rust APIs, so unsafe is allowed at the crate level here even though the workspace-wide policy (-W unsafe-code) forbids it everywhere else. Every unsafe block, unsafe impl, unsafe fn, and unsafe method in this crate carries a SAFETY: comment explaining why the required invariants hold — do not add a new unsafe site without one.