feat(ux): dark/light theme + en/ja i18n + user preferences

UX全体にテーマと言語設定を追加。 - lib/db/migrations/004_user_prefs.sql: users に theme/locale 列を追加(既定 dark/en) - lib/i18n/: dictionary(en/ja) + I18nProvider(クライアントcontext: locale/theme/t/setLocale/setTheme) + server.ts(SSR用 getLocale/getTheme/translate) + constants.ts - app/layout.tsx: theme/locale Cookie を読み <html class/lang> をSSR、I18nProvider でラップ(フラッシュなし) - tailwind darkMode:'class' + 全画面に dark: バリアントを一括付与(Nodeスクリプト lookbehind で安全に変換) - components/layout/ThemeToggle: 即時クラス切替+Cookie+永続化 - app/profile: テーマ/言語セレクタ、chrome翻訳(Header/ProjectNav/login/dashboard/profile) - PATCH /api/users/me: theme/locale を受理(バリデーション→400)、Cookieを設定 - E2E: locale=ja storageState で既存JAアサーションを維持、theme-i18n.spec で既定en/darkと切替を検証
2026-06-25 11:37:44 +02:00
parent 6a134a29bd
commit 921cdc457d
74 changed files with 1092 additions and 279 deletions
--- a/lib/i18n/I18nProvider.tsx
+++ b/lib/i18n/I18nProvider.tsx
@ -0,0 +1,99 @@
+'use client';
+
+import {
+  createContext,
+  useCallback,
+  useContext,
+  useMemo,
+  useState,
+  type ReactNode,
+} from 'react';
+import { useRouter } from 'next/navigation';
+import { dictionary, type MessageKey } from '@/lib/i18n/dictionary';
+import { PREF_MAX_AGE } from '@/lib/i18n/constants';
+import type { Locale, Theme } from '@/lib/types';
+
+interface I18nContextValue {
+  locale: Locale;
+  theme: Theme;
+  t: (key: MessageKey) => string;
+  setLocale: (locale: Locale) => void;
+  setTheme: (theme: Theme) => Promise<void>;
+}
+
+const I18nContext = createContext<I18nContextValue | null>(null);
+
+/**
+ * 言語とテーマのクライアント状態を提供するコンテキスト。
+ * - locale: 辞書の切り替え(t)と <html lang> の更新
+ * - setLocale/setTheme: Cookie を即時設定し /api/users/me で永続化、router.refresh でSSR再描画
+ */
+export function I18nProvider({
+  initialLocale,
+  initialTheme,
+  children,
+}: {
+  initialLocale: Locale;
+  initialTheme: Theme;
+  children: ReactNode;
+}) {
+  const router = useRouter();
+  const [locale, setLocaleState] = useState<Locale>(initialLocale);
+  const [theme, setThemeState] = useState<Theme>(initialTheme);
+
+  const t = useCallback(
+    (key: MessageKey) => dictionary[locale][key] ?? dictionary.en[key] ?? key,
+    [locale]
+  );
+
+  const persist = useCallback(async (body: Record<string, unknown>) => {
+    try {
+      await fetch('/api/users/me', {
+        method: 'PATCH',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify(body),
+      });
+    } catch (error) {
+      // 永続化失敗時もローカルCookieで動作継続するが、ログは残す
+      console.warn('Failed to persist user prefs:', error);
+    }
+  }, []);
+
+  const setLocale = useCallback(
+    (next: Locale) => {
+      setLocaleState(next);
+      document.cookie = `locale=${next}; path=/; max-age=${PREF_MAX_AGE}; samesite=lax`;
+      void persist({ locale: next });
+      router.refresh();
+    },
+    [persist, router]
+  );
+
+  const setTheme = useCallback(
+    async (next: Theme) => {
+      setThemeState(next);
+      const root = document.documentElement;
+      if (next === 'dark') root.classList.add('dark');
+      else root.classList.remove('dark');
+      root.style.colorScheme = next;
+      document.cookie = `theme=${next}; path=/; max-age=${PREF_MAX_AGE}; samesite=lax`;
+      await persist({ theme: next });
+    },
+    [persist]
+  );
+
+  const value = useMemo<I18nContextValue>(
+    () => ({ locale, theme, t, setLocale, setTheme }),
+    [locale, theme, t, setLocale, setTheme]
+  );
+
+  return <I18nContext.Provider value={value}>{children}</I18nContext.Provider>;
+}
+
+export function useI18n(): I18nContextValue {
+  const ctx = useContext(I18nContext);
+  if (!ctx) {
+    throw new Error('useI18n must be used within I18nProvider');
+  }
+  return ctx;
+}