Source Cursor rule: .cursor/rules/infra.mdc. Original Cursor alwaysApply: false.

Infrastructure

Package Manager

Use bun, never npm/yarn/pnpm.

bun install              # Install deps
bun add <pkg>            # Add package
bun add -D <pkg>         # Add dev dependency
bun run <script>         # Run script
bunx <cmd>               # Execute binary

Monorepo Structure

comp/
├── apps/
│   ├── api/             # NestJS backend
│   ├── app/             # Next.js main app
│   └── portal/          # Next.js portal
├── packages/
│   ├── db/              # Prisma (@trycompai/db)
│   ├── ui/              # Legacy UI (@trycompai/ui); prefer @trycompai/design-system
│   └── ...
├── turbo.json
└── package.json

Running Commands

# Multi-package (via turbo)
bun run build            # Build all
bun run lint             # Lint all
bun run typecheck        # Type check all
bun run dev              # Dev all

# Single package
bun run -F apps/app dev
bun run -F @trycompai/db prisma:generate
turbo build --filter=@trycompai/ui

Importing Between Packages

// ✅ Import from package name
import { Button } from '@trycompai/design-system';
import { prisma } from '@trycompai/db';

// ❌ Never relative paths across packages
import { Button } from '../../../packages/ui/src/button';

Adding Dependencies

# To specific package
bun add axios -F apps/app
bun add -D vitest -F @trycompai/ui

# To root (dev tools only)
bun add -D -w prettier typescript

After Code Changes

Always run checks:

bun run typecheck
bun run lint

Fix all errors before committing.

Common TypeScript Fixes

• Property does not exist: Check interface definitions
• Type mismatch: Verify expected vs actual type
• Empty interface extends: Use type X = SomeType instead

Common ESLint Fixes

• Unused variables: Remove or prefix with _
• Any type: Add proper typing
• Empty object type: Use type instead of interface

Creating a New Package

mkdir packages/my-package

// packages/my-package/package.json
{
  "name": "@trycompai/my-package",
  "version": "0.0.0",
  "private": true,
  "main": "./src/index.ts",
  "scripts": {
    "build": "tsup src/index.ts --format cjs,esm --dts",
    "typecheck": "tsc --noEmit"
  }
}

// packages/my-package/tsconfig.json
{
  "extends": "@trycompai/tsconfig/base.json",
  "include": ["src"]
}

Package Boundaries

✅ Create packages for:

• Code used by 2+ apps
• Self-contained, focused functionality

❌ Don't create packages for:

• Code only used in one app (colocate instead)
• App-specific business logic