Explanation

Why this crate exists

The desugarer was a one-off; most later passes had the same shape (bottom-up, remap, replace root). Generalising it into an engine turned passes into data and let kits compose them, while natives stayed the escape hatch for host-side operations.

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.