```typescript
/**
 * An append-only log of timestamped events.
 */
export class EventLog {
  /**
   * The private array of events.
   */
  #events: Event[] = [];

  /**
   * Append one event.
   *
   * @param event - The event to record.
   */
  record(event: Event): void {
    this.#events.push(event);
  }

  /**
   * Every event at or after the given timestamp, in insertion order.
   *
   * @param timestamp The maximum timestamp to include.
   * @returns A sorted array of events with timestamps greater than or equal to `timestamp`.
   */
  since(timestamp: number): Event[] {
    return [...this.#events].filter((event) => event.timestamp >= timestamp);
  }
}
```