[api-extractor] Missing 'export' keyword for namespace re-exports produces invalid TypeScript

[ItsChrisHickman]

[api-extractor] Missing export keyword for namespace re-exports produces invalid TypeScript

Summary

When a TypeScript source file contains a namespace with re-export declarations using export { } syntax, api-extractor strips the export keyword from the rollup output, producing syntactically invalid TypeScript.

Repro steps

1. Create a TypeScript file with a namespace that re-exports types:

export type Color = { r: number; g: number; b: number };
export type Vector3 = { x: number; y: number; z: number };

export declare namespace SDK {
  export { Color, Vector3 };
}

2. Run tsc to generate .d.ts files (output is correct)
3. Run api-extractor run --local to generate rollup
4. Check the output .d.ts rollup

Expected behavior

The rollup should contain:

export declare namespace SDK {
        export { Color, Vector3, };
}

Actual behavior

The rollup contains:

export declare namespace SDK {
        { Color, Vector3, };
}

The export keyword is missing, which produces invalid TypeScript:

error TS1109: Expression expected.

Root cause

In DtsRollupGenerator.ts (and ApiReportGenerator.ts), lines ~272-276 unconditionally skip all ExportKeyword tokens:

case ts.SyntaxKind.ExportKeyword:
case ts.SyntaxKind.DefaultKeyword:
case ts.SyntaxKind.DeclareKeyword:
  span.modification.skipAll();
  break;

The export keyword is then re-added for declaration types (interface, class, enum, namespace, function, type) at lines ~279-306. However, ExportDeclaration nodes (like export { Foo }) are not handled, so the export keyword is stripped but never restored.

Proposed fix

Check if the ExportKeyword is part of an ExportDeclaration inside a ModuleBlock (namespace body), and if so, preserve it:

case ts.SyntaxKind.ExportKeyword:
  // Preserve export keyword for ExportDeclarations inside namespaces
  if (span.node.parent && ts.isExportDeclaration(span.node.parent)) {
    const moduleBlock = TypeScriptHelpers.findFirstParent(
      span.node,
      ts.SyntaxKind.ModuleBlock
    );
    if (moduleBlock) {
      break; // Preserve the export keyword
    }
  }
  span.modification.skipAll();
  break;

Environment

• api-extractor version: 7.55.2
• TypeScript version: 5.x
• Node.js version: 20.x