TypeScript Strict Guidelines

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## Strict Configuration
Enable all strict checks in tsconfig.json:
- strict: true
- noUncheckedIndexedAccess: true
- exactOptionalPropertyTypes: true

## Type Patterns
```typescript
// Prefer interfaces for objects
interface User {
  id: string;
  email: string;
  role: 'admin' | 'user';
}

// Use type for unions and utilities
type UserRole = User['role'];
type PartialUser = Partial<User>;

// Generic constraints
function getProperty<T, K extends keyof T>(obj: T, key: K): T[K] {
  return obj[key];
}

// Type guards
function isUser(value: unknown): value is User {
  return typeof value === 'object' && value !== null && 'email' in value;
}
```

## Best Practices
- Never use 'any', prefer 'unknown' for truly unknown types
- Use discriminated unions for state machines
- Leverage utility types: Partial, Required, Pick, Omit
- Create branded types for IDs