Add compile-fail coverage for generated APIs: a surface include that exposes only one class must reject references to absent generated class names during cargo check.
req: codegen/001
req: style/002
req: test/003
Add a fixture-backed compile-fail test for generated slhx handler contracts: unknown handles and invalid handler shape fail during cargo check with actionable diagnostics.
req: derive_handler/001
req: test/003
slhx agent