Shared Package

Package: @my-app/shared
Path: packages/shared/

The shared package is the single source of truth for data types and validation schemas that are used by both the frontend and backend. It prevents type drift between the two apps.

Purpose

Define Zod schemas as the authoritative data contracts
Infer TypeScript types from those schemas (no manual type duplication)
Export everything from a single entry point (index.ts)
Build to both ESM and CJS for compatibility with Vue (ESM) and Node.js (CJS)

Package Exports

json

{
  "exports": {
    ".": {
      "import":  "./dist/index.js",
      "require": "./dist/index.cjs",
      "types":   "./dist/index.d.ts"
    }
  }
}

Build with:

bash

pnpm --filter @my-app/shared build
# runs: tsc --project tsconfig.json

Cross-App Import Rules

✅  apps/frontend   →  @my-app/shared
✅  apps/backend    →  @my-app/shared
❌  packages/shared →  apps/frontend   (FORBIDDEN)
❌  packages/shared →  apps/backend    (FORBIDDEN)

Adding a New Schema

Create packages/shared/src/schemas/<name>.schema.ts:

import { z } from 'zod'

export const DeviceSchema = z.object({
  _id:    z.string(),
  code:   z.string(),
  name:   z.string().optional(),
  unit_id: z.string().optional(),
})

export type Device = z.infer<typeof DeviceSchema>

Re-export from packages/shared/src/index.ts:

export { DeviceSchema, type Device } from './schemas/device.schema'

Re-export from packages/shared/src/types/index.ts if needed:

export type { Device } from '../schemas/device.schema'

Import in app code:

// In frontend (Vue)
import type { Device } from '@my-app/shared'

// In backend (Node.js)
import { DeviceSchema, type Device } from '@my-app/shared'
const parsed = DeviceSchema.parse(req.body)

Rebuild shared package:

bash

pnpm --filter @my-app/shared build

Dependency

zod@^3.22.0

Zod is the only runtime dependency. It provides both schema validation and TypeScript type inference, eliminating the need for separate validation and type-definition libraries.

Shared Package ​

Purpose ​

Package Exports ​

Cross-App Import Rules ​