Semantic compatibility

Oxc's transform conformance registry lists Stage 3 decorators and CommonJS module transformation as unsupported plugins (registry); exposed decorator options cover legacy decorators and metadata (options).

TypeScript namespaces are lowered into separate function expressions (namespace transform); mutable namespace exports trigger an explicit unsupported warning (diagnostic, call site).

export = is rewritten during statement traversal at its source location (module transform). Inference: assignment timing is observable when later statements inspect module.exports.