storybook/docs/_snippets/main-config-builder-custom-config.md

export default {
  stories: ['../src/**/*.mdx', '../src/**/*.stories.@(js|jsx|mjs|ts|tsx)'],
  core: {
    builder: {
      name: '@storybook/builder-vite',
      options: {
        viteConfigPath: '../customVite.config.js',
      },
    },
  },
};