test(ci): add exporter heading levels and a11y typography smoke; update MAIN_PLAN

lib/i18n/getMessages.ts

@@ -0,0 +1,8 @@
+import 'server-only'
+import { locales, type AppLocale } from '@/lib/i18n/locales'
+
+export async function getMessages(locale: AppLocale) {
+  const loc = locales.includes(locale) ? locale : 'en'
+  const messages = (await import(`@/messages/${loc}.json`)).default
+  return messages as Record<string, string>
+}

lib/i18n/i18n.test.ts

@@ -0,0 +1,25 @@
+import { describe, it, expect } from 'vitest'
+import { createI18n } from '@/lib/i18n'
+
+describe('i18n util', () => {
+  const i18n = createI18n({
+    defaultLocale: 'en',
+    messages: {
+      en: { hello: 'Hello {name}', onlyEn: 'Only EN' },
+      ko: { hello: '안녕하세요 {name}' },
+    },
+  })
+
+  it('로케일별 번역과 변수 치환을 지원한다', () => {
+    expect(i18n.t('en', 'hello', { name: 'Jay' })).toBe('Hello Jay')
+    expect(i18n.t('ko', 'hello', { name: '제이' })).toBe('안녕하세요 제이')
+  })
+
+  it('키가 없으면 기본 로케일로 폴백한다', () => {
+    expect(i18n.t('ko', 'onlyEn')).toBe('Only EN')
+  })
+
+  it('완전히 없는 키는 키 그대로 반환한다', () => {
+    expect(i18n.t('en', 'missing.key')).toBe('missing.key')
+  })
+})

lib/i18n/index.ts

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+type Messages = Record<string, Record<string, string>>
+
+export function createI18n({ defaultLocale, messages }: { defaultLocale: string; messages: Messages }) {
+  function format(template: string, params?: Record<string, string | number>) {
+    if (!params) return template
+    return template.replace(/\{(\w+)\}/g, (_, k) => (params[k] !== undefined ? String(params[k]) : `{${k}}`))
+  }
+
+  function getMessage(locale: string, key: string): string | undefined {
+    const m = messages[locale] || {}
+    if (m[key] !== undefined) return m[key]
+    const base = messages[defaultLocale] || {}
+    return base[key]
+  }
+
+  function t(locale: string, key: string, params?: Record<string, string | number>): string {
+    const msg = getMessage(locale, key)
+    if (typeof msg === 'string') return format(msg, params)
+    return key
+  }
+
+  return { t }
+}

lib/i18n/locales.ts

@@ -0,0 +1,3 @@
+export const locales = ['en', 'ko'] as const
+export type AppLocale = typeof locales[number]
+export const defaultLocale: AppLocale = 'en'