Reference

Public API

item	what it is
TypecheckEngine	the trait a checker implements
TypecheckRequest / TypecheckResult	input (AST, language, options) and output (diagnostics, accepted AST)
TypecheckReport / TypecheckDiagnostic	structured, renderable diagnostics
check_module, check_module_with_prelude	convenience entry points, optionally seeding a prelude
CheckError, is_clean	failure kind, and the quick «no diagnostics» test

Crate

crate	role
hnl-engine-typecheck	abstraction + bootstrap checker

Build and test

cargo build     # sibling [patch] tables resolve deps from ../<repo>
cargo test      # cargo test

Dependencies are git deps on branch = "main"; locally the [patch] tables point at sibling checkouts (regenerated by host/scripts/dev-link.sh).