desktop 앱 적용

frontend/src/utils/desktopSync.ts

@@ -0,0 +1,43 @@
+/** 데스크톱 메인↔위젯 창 상태 동기화 (localStorage) */
+export const DESKTOP_SYNC_KEY = 'gc_desktop_sync';
+
+export interface DesktopSyncState {
+  selectedMarket?: string;
+  selectedStrategyId?: number | null;
+  theme?: string;
+  updatedAt: number;
+}
+
+export function readDesktopSync(): DesktopSyncState | null {
+  try {
+    const raw = localStorage.getItem(DESKTOP_SYNC_KEY);
+    if (!raw) return null;
+    return JSON.parse(raw) as DesktopSyncState;
+  } catch {
+    return null;
+  }
+}
+
+export function writeDesktopSync(partial: Omit<DesktopSyncState, 'updatedAt'>): void {
+  const prev = readDesktopSync() ?? { updatedAt: 0 };
+  const next: DesktopSyncState = {
+    ...prev,
+    ...partial,
+    updatedAt: Date.now(),
+  };
+  try {
+    localStorage.setItem(DESKTOP_SYNC_KEY, JSON.stringify(next));
+  } catch {
+    /* ignore */
+  }
+}
+
+export function subscribeDesktopSync(cb: (state: DesktopSyncState) => void): () => void {
+  const onStorage = (e: StorageEvent) => {
+    if (e.key !== DESKTOP_SYNC_KEY) return;
+    const state = readDesktopSync();
+    if (state) cb(state);
+  };
+  window.addEventListener('storage', onStorage);
+  return () => window.removeEventListener('storage', onStorage);
+}