rspack in monorepo mode + CJS seems to drop exports in main.ts

Is there an existing issue for this?

• I have searched the existing issues

Current behavior

rspack in monorepo mode + CJS ignores the exports in main.ts.

main.ts:

let handler = defineAPIGatewayHandler({
  appModule: AppModule,
  authConf: 'admin',
  basePath: '/web/admin',
});

export { handler };

Output of main.js:

let handler = (0,_lib_cli__rspack_import_0.defineAPIGatewayHandler)({
    appModule: _AppModule__rspack_import_1.AppModule,
    authConf: 'admin',
    basePath: '/web/admin'
});


})();

})()
;
//# sourceMappingURL=main.js.map

---

When running in ESM mode, the output emits export { } as expected.

Output of main.js:

let handler = (0,_lib_cli_index_js__rspack_import_0.defineAPIGatewayHandler)({
    appModule: _AppModule_js__rspack_import_1.AppModule,
    authConf: 'admin',
    basePath: '/web/admin'
});

/* snip */

var __webpack_exports__ = __webpack_require__("./apps/admin/src/main.ts");
var __webpack_exports__handler = __webpack_exports__.handler;
export { __webpack_exports__handler as handler };

//# sourceMappingURL=main.js.map

---

When running tsc in CJS mode, the output emits export.handler = handler as expected.

Output of main.js:

let handler = (0, cli_1.defineAPIGatewayHandler)({
    appModule: AppModule_1.AppModule,
    authConf: 'admin',
    basePath: '/web/admin',
});
exports.handler = handler;
//# sourceMappingURL=main.js.map

Minimum reproduction code

Steps to reproduce

No response

Expected behavior

export.handler = handler should be emitted.

Package version

12.0.1

NestJS version

12.0.1

Node.js version

v22.23.2

In which operating systems have you tested?

• macOS
• Windows
• Linux

Other

No response

Start with the reported main.ts example and compare the CJS output with the ESM and tsc outputs shown in the issue. Reproduce the behavior using nest-cli 12.0.1 in monorepo mode, then trace the CJS bundling path to determine why the export is omitted. Done means the generated main.js emits export.handler = handler for the CJS case.