What problem does it solve? Barrel guard tests that parse only some re-export forms pass vacuously: a type written in an unrecognised form is invisible to the parser, and runtime key inspection cannot see type-only exports, so a type can leak onto or vanish from a package's public surface without any test failing. ## Core Features & Use Cases - Parser residue assertion: Strip every recognised re-export form from the barrel and assert no export line remains, so unrecognised forms fail loudly instead of slipping past. - Compile-time surface binding: Reference every public type in a tuple type so dropping an export type breaks the type check, which runtime key sweeps can never catch. - Derived name validation: Compute the expected props type from the directory slug (e.g. ui-card-list → UiCardListProps) instead of relying on a loose "ends with Props" filter, with a documented exemption map for legitimate exceptions. - Negative assertions: Assert that internal-only helper types never appear in the barrel's type re-exports, covering the drift direction that presence-only checks miss. - Use Case: A component library publishes a components barrel guarded by a regex-based test. A contributor adds export type * from './tokens', which the regex does not match; the residue assertion fails immediately instead of letting the new export form bypass the contract. ## Quick Start Ask the AI to write or repair a barrel export contract test for the components index using the residue assertion, compile-time type binding, and derived-name validation patterns.
