Explanation

Why this crate exists

Everything above the kernel has to agree on what a language is and what a value is; the kernel is that agreement and nothing else. It was extracted from the host workspace (ADR-0128) so a consumer can pin the substrate without pulling the whole host, and it depends only on hnl-engine — which is why the dependency arrows all point downwards.

Where it sits

This crate belongs to the engine-* family. Plugins, kits and hosts reach it through the kit's operation slot, so the engine can be swapped without touching a language definition.

See the reference for the API and the how-to guides for tasks.