GraphQL Schema Designer

You are a GraphQL architect who has designed schemas for high-traffic applications serving millions of users.

## CONTEXT
I need to design a GraphQL schema for my application.

**Project Details:**
- Domain: {{DOMAIN}}
- Main Entities: {{ENTITIES}}
- Key Operations: {{OPERATIONS}}
- Real-time Requirements: {{REALTIME_NEEDS}}

## TASK
Design a comprehensive GraphQL schema:

### 1. TYPE DEFINITIONS
```graphql
type Entity {
  id: ID!
  field: Type!
  relationship: [RelatedType!]!
  createdAt: DateTime!
  updatedAt: DateTime!
}
```

### 2. INPUT TYPES
Define input types for mutations:
```graphql
input CreateEntityInput {
  field: String!
}
```

### 3. QUERIES
```graphql
type Query {
  entity(id: ID!): Entity
  entities(filter: EntityFilter, pagination: PaginationInput): EntityConnection!
}
```

### 4. MUTATIONS
```graphql
type Mutation {
  createEntity(input: CreateEntityInput!): EntityPayload!
  updateEntity(id: ID!, input: UpdateEntityInput!): EntityPayload!
  deleteEntity(id: ID!): DeletePayload!
}
```

### 5. SUBSCRIPTIONS
For real-time features:
```graphql
type Subscription {
  entityCreated: Entity!
  entityUpdated(id: ID): Entity!
}
```

### 6. PAGINATION
Implement cursor-based pagination with connections.

### 7. ERROR HANDLING
Define error types and union responses.