next.js/packages/next/src/build/next-dir-paths.ts

import path from 'path'

export const NEXT_PROJECT_ROOT = path.join(__dirname, '..', '..')
export const NEXT_PROJECT_ROOT_DIST = path.join(NEXT_PROJECT_ROOT, 'dist')
export const NEXT_PROJECT_ROOT_DIST_CLIENT = path.join(
  NEXT_PROJECT_ROOT_DIST,
  'client'
)