앱을 종료할 때 - 전체 화면 모드 상태 여부, 화면 크기, 화면 위치 정보를 저장

AGENTS.md

@@ -29,6 +29,7 @@ assets/
 src/
 ├── main/
 │   ├── index.js          # Main process entry point; app.setName(), BrowserWindow, registerAll()
+│   ├── config.js         # Shared userData/config.json read/write helpers
 │   └── ipc/
 │       ├── index.js      # registerAll(mainWindow) — delegates to folder and files modules
 │       ├── file-utils.js # Shared main-process file helpers: image listing/data URLs,
@@ -189,4 +190,4 @@ Global shortcuts are registered in `keyboard.js`. They do not fire while any `.m
 
 **Build output:** `electron-builder` targets DMG for arm64 and x64.
 
-**Config persistence:** `app.getPath('userData')/config.json`에 `lastFolder`, `previewOn` 저장.
+**Config persistence:** `app.getPath('userData')/config.json`에 `lastFolder`, `previewOn`, `sidebarWidth`, `windowState` 저장. `windowState` includes fullscreen status and normal window bounds (`x`, `y`, `width`, `height`) and is restored on startup if the saved bounds overlap an available display.