Prerequisites checklist

• I have read the contributing guidelines.

AI acknowledgment

• I did not use AI to generate this PR.
• (If the above is not checked) I have reviewed the AI-generated content before submitting.

What is the purpose of this pull request?

This PR simplifies CommonJS types by re-exporting ESM types.

Most packages in this repo export types both in CommonJS and ESM format, which is necessary for compatibility with both module systems. Today, the CommonJS declarations duplicate the ESM declarations with only small replacements to match import paths. For example, these are the ESM type declarations for @eslint/[email protected]:

• dist/esm/index.d.ts
• dist/esm/types.ts

And these are the corresponding, very similar CommonJS declarations:

• dist/cjs/index.d.cts
• dist/cjs/types.cts

To avoid the duplication and reduce the published package size, this PR changes the CommonJS type declarations to one single file that just re-exports the ESM types:

// dist/cjs/index.d.cts
import type * as types from "../esm/index.js" with { "resolution-mode": "import" };
export = types;

This is now possible thanks to the resolution-mode import attribute, which has been supported since TypeScript 5.3, the earliest TypeScript version supported by ESLint.

This change affects all packages that use the build:cts script, i.e.:

• compat
• config-array
• config-helpers
• core
• object-schema
• plugin-kit

What changes did you make? (Give an overview)

• Updated tools/build-cts.js script re-exports ESM type declarations instead of duplicating them.
• Updated Rollup configurations so that dist/cjs/types.cts files are no longer created.
• Updated build:cts script in core package to use the new script.

Related Issues

refs eslint/eslint#19920

Is there anything you'd like reviewers to focus on?