/**
 * Formatter contract
 * 
 * Deterministic, reusable, UI-only formatting/mapping logic.
 * 
 * Based on DISPLAY_OBJECTS.md:
 * - Class-based
 * - Immutable
 * - Deterministic
 * - Side-effect free
 * - No Intl.* or toLocale*
 * - No business rules
 */

export interface Formatter {
  /**
   * Format or map the display object
   * 
   * @returns Primitive values only (strings, numbers, booleans)
   */
  format(): unknown;
}