src/lib/utils/locale.ts

/**
 * Visitor-language helpers.
 *
 * Only the example prompt and sentence segmentation follow the browser's
 * language; the interface itself stays in English.
 */

const FALLBACK = 'en';

/** The visitor's preferred language tag, e.g. "ko-KR". */
export function browserLocale(): string {
  if (typeof navigator === 'undefined') return FALLBACK;
  return navigator.language || FALLBACK;
}

/** Base language subtag, e.g. "ko". */
export function browserLanguage(): string {
  return browserLocale().toLowerCase().split('-')[0];
}

export function isKorean(): boolean {
  return browserLanguage() === 'ko';
}

/** Example prompt to start from, in the visitor's language. */
export function defaultPrompt(): string {
  return isKorean()
    ? '가을과 관련된 작은 시 한편을 써줘.'
    : 'Write a short poem about autumn.';
}