TypeScript Rules

Types

• •Never use any — use unknown with type guards or explicit types
• •Prefer interface for object shapes, type for unions/intersections
• •Export types alongside their functions, not from barrel files
• •Use satisfies for type-safe object literals: const x = { ... } satisfies Config

Imports

• •Use @/ path alias for imports from apps/web/src/
• •Group imports: external libs → @/lib/ → relative slice imports
• •Use type imports for type-only: import type { Foo } from './types'

Error Handling

• •Throw typed errors, not strings: throw new Error('message')
• •Use discriminated unions for result types: { ok: true; data: T } | { ok: false; error: string }
• •Catch unknown, narrow with instanceof

Functions

• •Prefer named function declarations over arrow functions for top-level exports
• •Use explicit return types on exported functions
• •Keep functions small — max ~50 lines

Zod

• •Validate all external input (API responses, form data, URL params) with Zod
• •Co-locate schemas with server functions, not in separate schema files
• •Use z.infer<typeof schema> for derived types