Ship is monorepo, so it lets you share your code across applications to minimize duplications and reduce errors. All shared code are inside packages/ folder. By default, packages include app-constants, app-types, enums, schemas and mailer. Learn more about the mailer package here. 
/packages
  /app-constants
  /app-types
  /enums
  /mailer
  /schemas

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Installation

We’ve included all essential packages in your apps. If you want to add more packages, head to the package.json file, and in the dependencies section, add to dependencies package name with value “workspace:*”.
apps/web/package.json
"dependencies": {
    "app-constants": "workspace:*",
    "app-types": "workspace:*",
    "schemas": "workspace:*",
  },
The enums package comes with app-types, so no separate import is needed.
You can read more about package sharing in Turborepo documentation.