I've tested against the ./example/1.zero-config and the output of utils.d.cts has changed from:

declare function sum(a: number, b: number): number;

export { sum as default };

to:

declare function sum(a: number, b: number): number;

export = sum;

This is the expected types in pair with the utils.cjs output:

'use strict';

function sum(a, b) {
  return a + b;
}

module.exports = sum;

Looks like we also need to include also this change for d.ts files for node10 module resolution: I'm updating unbuild to 3.2.0 in UnoCSS repo and d.ts files are wrong.

that would depend on whether it was type: module, i assume?

yes, we also have some problems with CJS and node16, for example, postcss package exporting default and a type, this PR doesn't change it:

// d.cts
export { type UnoPostcssPluginOptions, unocss as default };

should be:

export = unocss;
export { type UnoPostcssPluginOptions };

Even with type set to commonjs, unbuild generating wrong dts files, check #474, reproduction there