`hc-spin-rust-utils` is a Node.js add-on that provides Rust utilities for Holochain development tools. It offers functions for unpacking `.webhapp` files and signing zome calls using a lair keystore, primarily serving as a dependency for `hc-spin` and `kangaroo-electron`. This package is intended for Holochain developers working with Rust-based add-ons in their development workflow.