役目を終えたアプリをどう畳むか — 更新停止から完全終了までを先に設計する

// app-status.ts — 配信側は CDN 上の静的 JSON 1枚
import AsyncStorage from "@react-native-async-storage/async-storage";
 
export type SunsetMode = "active" | "notice" | "readonly" | "ended";
 
export interface AppStatus {
  mode: SunsetMode;
  message?: string;      // 告知文（端末ロケールで日英を出し分け）
  exportUntil?: string;  // データ持ち出しの期限（ISO 8601）
  learnMoreUrl?: string; // 詳細案内ページ
}
 
const STATUS_URL = "https://static.example.com/app-status/my-app.json";
const CACHE_KEY = "app_status_cache_v1";
 
export async function fetchAppStatus(): Promise<AppStatus> {
  try {
    const res = await fetch(STATUS_URL, {
      headers: { "cache-control": "no-cache" },
    });
    if (!res.ok) throw new Error(`status ${res.status}`);
    const status = (await res.json()) as AppStatus;
    await AsyncStorage.setItem(CACHE_KEY, JSON.stringify(status));
    return status;
  } catch {
    // 取得失敗時は前回値へフォールバック。
    // 前回値もなければ active 扱いにして通常起動を守る
    const cached = await AsyncStorage.getItem(CACHE_KEY);
    return cached ? (JSON.parse(cached) as AppStatus) : { mode: "active" };
  }
}

// App.tsx — 起動時に一度だけ判定する
const [status, setStatus] = useState<AppStatus>({ mode: "active" });
 
useEffect(() => {
  fetchAppStatus().then(setStatus);
}, []);
 
if (status.mode === "ended") {
  return <SunsetScreen status={status} />; // 終了画面（持ち出し導線つき）
}
return (
  <>
    {status.mode !== "active" && <SunsetBanner status={status} />}
    <MainApp readonly={status.mode === "readonly"} />
  </>
);

// export-user-data.ts
import AsyncStorage from "@react-native-async-storage/async-storage";
import * as FileSystem from "expo-file-system";
import * as Sharing from "expo-sharing";
 
export async function exportUserData(): Promise<void> {
  const favorites = await AsyncStorage.getItem("favorites_v2");
  const settings = await AsyncStorage.getItem("settings_v1");
 
  const payload = {
    exportedAt: new Date().toISOString(),
    schemaVersion: 2,
    favorites: favorites ? JSON.parse(favorites) : [],
    settings: settings ? JSON.parse(settings) : {},
  };
 
  const uri = FileSystem.cacheDirectory + "my-data-export.json";
  await FileSystem.writeAsStringAsync(uri, JSON.stringify(payload, null, 2));
  await Sharing.shareAsync(uri, { mimeType: "application/json" });
}