Current Behavior

When generating a publishable library using the @nx/js generator with the Rollup bundler, the nx build command produces a type declaration file (index.cjs.d.ts) that is not consistent with the types field in the generated package.json.

Specifically:

1. The Rollup config generates index.cjs.d.ts in the dist directory.
2. The types field in package.json is set to ./dist/index.d.ts.
3. Similarly, the exports section refers to ./dist/index.d.ts for the types key

"exports": {
  "./package.json": "./package.json",
  ".": {
    "types": "./dist/index.d.ts",
    "import": "./dist/index.esm.js",
    "default": "./dist/index.cjs.js"
  },
"types": "./dist/index.d.ts"
}

As a result, when the package is consumed outside the workspace, TypeScript fails to locate the type declarations.

Error example:

Could not find a declaration file for module '@myorg/example'. 
Module implicitly has an 'any' type because 'index.cjs.d.ts' does not match the 'types' field.

Expected Behavior

The generated file names and package.json configuration should align. The following adjustment(s) could resolve the issue:

1. The Rollup bundler should produce a type declaration file named index.d.ts (instead of index.cjs.d.ts).

GitHub Repo

No response

Steps to Reproduce

1. Create a publishable library with Rollup bundler: npx nx g @nx/js:library packages/example-types --bundler=rollup --publishable --importPath=@myorg/example
2. Build the library: npx nx build example-types
3. Inspect the output directory and package.json:

• Output includes index.cjs.d.ts in the dist folder.
• package.json has a types field pointing to ./dist/index.d.ts and an exports entry for types pointing to the same file.

4. Attempt to use the package in an external project:

• Install the package and observe that TypeScript cannot resolve the type declarations.

resulting dist directory:

dist/
  index.cjs.js
  index.esm.js
  index.cjs.d.ts

generated package.json:

{
  "types": "./dist/index.d.ts",
  "exports": {
    "./package.json": "./package.json",
    ".": {
      "types": "./dist/index.d.ts",
      "import": "./dist/index.esm.js",
      "default": "./dist/index.cjs.js"
    }
  }
}

Nx Report

NX   Report complete - copy this into the issue template

Node           : 22.11.0
OS             : darwin-arm64
Native Target  : aarch64-macos
yarn           : 4.5.3

nx                     : 20.2.2
@nx/js                 : 20.2.2
@nx/jest               : 20.2.2
@nx/eslint             : 20.2.2
@nx/workspace          : 20.2.2
@nx/devkit             : 20.2.2
@nx/eslint-plugin      : 20.2.2
@nx/module-federation  : 20.2.2
@nx/next               : 20.2.2
@nx/react              : 20.2.2
@nx/rollup             : 20.2.2
@nx/web                : 20.2.2
@nx/webpack            : 20.2.2
typescript             : 5.6.3
---------------------------------------
Registered Plugins:
@nx/js/typescript
@nx/eslint/plugin
@nx/jest/plugin
@nx/next/plugin
@nx/rollup/plugin

Failure Logs

Package Manager Version

No response

Operating System

• macOS
• Linux
• Windows
• Other (Please specify)

Additional Information

No response