diff --git a/CLAUDE.md b/CLAUDE.md
index bf70cb5..b6f1226 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -15,7 +15,7 @@ There are no tests or linting configured.
 
 ## Architecture
 
-This is a macOS Electron desktop app for batch-renaming photo files. It follows strict Electron security practices: `contextIsolation: true`, `nodeIntegration: false`.
+This is a macOS Electron desktop app for batch-renaming and moving photo files. It follows strict Electron security practices: `contextIsolation: true`, `nodeIntegration: false`.
 
 **Process boundary:** All filesystem access lives exclusively in `src/main/` (main process). The renderer never touches `fs` directly.
 
@@ -27,20 +27,27 @@ src/
 │   ├── index.js          # Main process entry point; creates BrowserWindow, calls registerAll()
 │   └── ipc/
 │       ├── index.js      # registerAll(mainWindow) — delegates to folder and files modules
-│       ├── folder.js     # select-folder, reveal-folder
-│       └── files.js      # list-images, read-image, rename-files
+│       ├── folder.js     # select-folder, list-directories, get/set-last-folder,
+│       │                 # get/set-preview-on, get-home-dir, reveal-folder
+│       └── files.js      # list-images, read-image, rename-files,
+│                         # check-files-exist, move-files
 ├── preload/
 │   └── index.js          # Bridges IPC to window.api via contextBridge (isolated context)
 └── renderer/
-    ├── index.html        # App shell (dark theme, CSS variables in :root)
+    ├── index.html        # App shell; dark theme, CSS variables in :root, modal HTML
     ├── style.css         # All CSS
-    ├── renderer.js       # Main renderer logic; imports state and handlers
     ├── state.js          # Shared mutable state: files[], currentFolder, selectedIdxs, sortMode
+    ├── renderer.js       # Entry point: init, loadFolder, sortFiles, keyboard shortcuts, startup
+    ├── ui.js             # showLoading, hideLoading, setStatus, showToast
+    ├── grid.js           # renderGrid, createCard, card UI update functions, showEmptyGrid
+    ├── rename.js         # doRename + rename-conflict modal
+    ├── move.js           # handleFolderDrop + move modals + _doMoveFiles
     └── handlers/
-        ├── drag-drop.js  # Card drag-and-drop reorder (single and multi-card)
-        ├── selection.js  # Rubber-band selection, Shift-click, Cmd+click
-        ├── pinch-zoom.js # Trackpad pinch to resize thumbnails (CSS --thumb-size, 150–400px)
-        └── image-preview.js # Hover preview overlay
+        ├── drag-drop.js      # Card reorder (single/multi) + drag-to-folder in sidebar
+        ├── file-explorer.js  # Sidebar directory tree (lazy-load, expand/collapse)
+        ├── selection.js      # Rubber-band, Shift-click, Cmd+click, resetAnchor
+        ├── pinch-zoom.js     # Ctrl+scroll to resize thumbnails (CSS --thumb-size, 150–400px)
+        └── image-preview.js  # Hover preview overlay with circular loading indicator
 ```
 
 ### IPC surface
@@ -50,9 +57,15 @@ Defined in `src/main/ipc/`, bridged via `src/preload/index.js` as `window.api`:
 | Channel | Direction | Description |
 |---|---|---|
 | `select-folder` | invoke | Opens native folder picker, returns path or null |
-| `list-images` | invoke | Reads directory, returns `{name, path, mtime, size}[]` filtered to image extensions, sorted by filename |
+| `list-images` | invoke | Reads directory, returns `{name, path, mtime}[]` filtered to image extensions, sorted by filename |
 | `read-image` | invoke | Reads file, returns base64 data URL for display |
-| `rename-files({folderPath, files, prefix, digits})` | invoke | Two-phase rename: temp names first, then final names to avoid collisions |
+| `rename-files({folderPath, files, prefix, digits})` | invoke | Two-phase rename: temp names (crypto.randomUUID) first, then final names |
+| `check-files-exist(folderPath, names[])` | invoke | Returns subset of names that already exist in folderPath |
+| `move-files({targetFolder, files[]})` | invoke | Moves files; each file may have optional `newName`; handles cross-device (EXDEV) |
+| `list-directories(folderPath)` | invoke | Returns `{name, path, hasChildren}[]` subdirs, or `null` on access error |
+| `get-home-dir` | invoke | Returns `os.homedir()` |
+| `get-last-folder` / `set-last-folder` | invoke | Persists last opened folder in userData config.json |
+| `get-preview-on` / `set-preview-on` | invoke | Persists hover preview toggle state in userData config.json |
 | `reveal-folder` | invoke | Opens folder in Finder via `shell.openPath` |
 | `fullscreen-change` | push (main→renderer) | Sent on `enter-full-screen` / `leave-full-screen` window events |
 
@@ -60,14 +73,54 @@ Defined in `src/main/ipc/`, bridged via `src/preload/index.js` as `window.api`:
 
 Uses ES module imports (`type="module"`). No framework.
 
+**Dependency direction** (no cycles):
+```
+renderer.js → rename.js, move.js → grid.js → handlers/*
+                                 ↘         ↗
+                                   ui.js
+```
+
 **State** (`src/renderer/state.js`):
-- `files[]` — ordered array of file objects; order determines rename sequence
+- `files[]` — ordered array of `{name, path, mtime}`; order determines rename sequence
 - `selectedIdxs` — `Set<number>` of selected card indices
 - `currentFolder` — active directory path
 - `sortMode` — `'name'` | `'date'` | `null`
 
-**Thumbnail loading:** Uses `IntersectionObserver` with `rootMargin: '400px 0px'` — images load lazily as cards enter the viewport. DOM card elements are created immediately without `src`; the observer fills in `img.src` on entry. Drag-and-drop reorder remaps existing card elements via `card.dataset.filepath` to avoid re-fetching images.
+**Keyboard shortcuts:**
+- `O` — 폴더 열기
+- `S` — 이름 변경 실행
+- `A` — 전체 선택
 
-**Styling:** All CSS lives in `src/renderer/index.html`. Dark theme with CSS variables defined in `:root`. The macOS traffic-light buttons sit in `#titlebar` with `-webkit-app-region: drag`.
+**Card selection** (`selection.js`):
+- Click — 단독 선택 (재클릭 시 해제)
+- Shift+Click — 범위 선택
+- Cmd+Click — 개별 토글
+- Rubber-band drag — 영역 선택 (rAF throttle 적용)
+- `resetAnchor()` — 그리드 재렌더 시 Shift 기준점 초기화 (grid.js에서 호출)
+
+**Drag-and-drop** (`drag-drop.js`):
+- 그리드 내: 카드 순서 재배치 (single/multi)
+- 사이드바 폴더로: 선택된 파일들을 해당 폴더로 이동
+  - 파일명 충돌 시 rename-and-move 모달 표시
+  - 드래그 중 `.tree-row.drop-target` 클래스로 대상 폴더 하이라이트
+
+**Rename** (`rename.js`):
+- 선택된 파일만 이름 변경 (선택 없으면 전체)
+- 변경될 이름이 미선택 파일과 충돌하면 충돌 목록 모달 표시
+
+**Move** (`move.js`):
+- 충돌 없으면 즉시 이동
+- 충돌 있으면 prefix + digits 입력 모달 → 새 이름으로 이동
+- 새 이름도 충돌이면 에러 모달
+
+**Thumbnail loading:** `IntersectionObserver` with `rootMargin: '400px 0px'` — lazy load as cards enter viewport. `entry.target.isConnected` 체크로 폴더 전환 중 스탈 카드 방지. Drag reorder remaps card elements via `card.dataset.filepath` to avoid re-fetching.
+
+**Hover preview** (`image-preview.js`): 1초 지연 후 전체 크기 팝업. 썸네일 캐시 우선 사용. 상태는 config.json에 영속.
+
+**Sidebar tree** (`file-explorer.js`): Lazy-load 자식 폴더. 접근 불가 폴더는 `null` 반환 → "접근 불가" 표시. 행 클릭 시 항상 펼침, 화살표 클릭 시 토글.
+
+**Styling:** CSS는 `src/renderer/style.css`에 집중. Dark theme, CSS variables in `:root`. macOS traffic-light은 `header`의 `-webkit-app-region: drag`.
 
 **Build output:** `electron-builder` targets DMG for arm64 and x64. The app icon must be at `assets/icon.icns`.
+
+**Config persistence:** `app.getPath('userData')/config.json`에 `lastFolder`, `previewOn` 저장.
diff --git a/src/main/ipc/files.js b/src/main/ipc/files.js
index 72c1d46..49eea60 100644
--- a/src/main/ipc/files.js
+++ b/src/main/ipc/files.js
@@ -1,6 +1,7 @@
 const { ipcMain } = require('electron');
 const path = require('path');
 const fs = require('fs');
+const crypto = require('crypto');
 
 const EXTS = new Set(['.jpg', '.jpeg', '.png', '.gif', '.bmp', '.tiff', '.tif', '.webp', '.heic', '.heif']);
 
@@ -12,7 +13,7 @@ function register() {
         .map(f => {
           const fullPath = path.join(folderPath, f);
           const stat = fs.statSync(fullPath);
-          return { name: f, path: fullPath, mtime: stat.mtimeMs, size: stat.size };
+          return { name: f, path: fullPath, mtime: stat.mtimeMs };
         })
         .sort((a, b) => a.name.localeCompare(b.name, 'ko'));
       return files;
@@ -78,7 +79,7 @@ function register() {
     for (let i = 0; i < files.length; i++) {
       const src = files[i].path;
       const ext = path.extname(files[i].name).toLowerCase();
-      const tmp = path.join(folderPath, `__tmp_rename_${i}_${Date.now()}${ext}`);
+      const tmp = path.join(folderPath, `__tmp_${crypto.randomUUID()}${ext}`);
       try {
         fs.renameSync(src, tmp);
         tmpMap.push({ tmp, ext, idx: i });
diff --git a/src/main/ipc/folder.js b/src/main/ipc/folder.js
index 6f36724..28478a0 100644
--- a/src/main/ipc/folder.js
+++ b/src/main/ipc/folder.js
@@ -53,7 +53,7 @@ function register(mainWindow) {
           return { name: e.name, path: fullPath, hasChildren };
         })
         .sort((a, b) => a.name.localeCompare(b.name));
-    } catch { return []; }
+    } catch { return null; }
   });
 
   ipcMain.handle('reveal-folder', (_e, folderPath) => shell.openPath(folderPath));
diff --git a/src/preload/index.js b/src/preload/index.js
index a99b63f..ce723b6 100644
--- a/src/preload/index.js
+++ b/src/preload/index.js
@@ -5,7 +5,11 @@ contextBridge.exposeInMainWorld('api', {
   listImages:         (folder)   => ipcRenderer.invoke('list-images', folder),
   readImage:          (path)     => ipcRenderer.invoke('read-image', path),
   renameFiles:        (args)     => ipcRenderer.invoke('rename-files', args),
-  onFullscreenChange: (callback) => ipcRenderer.on('fullscreen-change', (_e, v) => callback(v)),
+  onFullscreenChange: (() => {
+    let _cb = null;
+    ipcRenderer.on('fullscreen-change', (_e, v) => { if (_cb) _cb(v); });
+    return (callback) => { _cb = callback; };
+  })(),
   getHomeDir:         ()         => ipcRenderer.invoke('get-home-dir'),
   getLastFolder:      ()         => ipcRenderer.invoke('get-last-folder'),
   setLastFolder:      (p)        => ipcRenderer.invoke('set-last-folder', p),
diff --git a/src/renderer/grid.js b/src/renderer/grid.js
index 347d942..c99cc4f 100644
--- a/src/renderer/grid.js
+++ b/src/renderer/grid.js
@@ -31,13 +31,14 @@ export function renderGrid() {
       const img = entry.target.querySelector('img.card-thumb');
       if (!img || img.src) return;
       const dataUrl = await window.api.readImage(entry.target.dataset.filepath);
-      if (dataUrl) img.src = dataUrl;
+      if (dataUrl && entry.target.isConnected) img.src = dataUrl;
     });
   }, { root: gridContainer, rootMargin: '400px 0px', threshold: 0 });
 
   Array.from(grid.children).forEach(card => observer.observe(card));
   _cardObserver = observer;
 
+  selection.resetAnchor();
   refreshCardSelection();
   updateNumberBadges();
   updateNewNameLabels();
diff --git a/src/renderer/handlers/file-explorer.js b/src/renderer/handlers/file-explorer.js
index c1c0a0f..0e8b6ef 100644
--- a/src/renderer/handlers/file-explorer.js
+++ b/src/renderer/handlers/file-explorer.js
@@ -125,7 +125,14 @@ async function expandNode(nodeEl, autoExpandPath) {
   if (!childrenEl.dataset.loaded) {
     childrenEl.dataset.loaded = 'true';
     const dirs = await window.api.listDirectories(nodeEl.dataset.path);
-    dirs.forEach(dir => childrenEl.appendChild(createNode(dir)));
+    if (dirs === null) {
+      const err = document.createElement('div');
+      err.className = 'tree-access-error';
+      err.textContent = '접근 불가';
+      childrenEl.appendChild(err);
+    } else {
+      dirs.forEach(dir => childrenEl.appendChild(createNode(dir)));
+    }
   }
 
   // Auto-expand toward the target path
diff --git a/src/renderer/handlers/selection.js b/src/renderer/handlers/selection.js
index 3e2f8a9..3bf03bb 100644
--- a/src/renderer/handlers/selection.js
+++ b/src/renderer/handlers/selection.js
@@ -4,9 +4,15 @@ let _state, _cb;
 let rbActive = false;
 let rbStartX = 0;
 let rbStartY = 0;
+let _rafPending   = false;
+let _lastMoveEvent = null;
 
 let lastSelectedIdx = null;
 
+export function resetAnchor() {
+  lastSelectedIdx = null;
+}
+
 export function init({ gridContainer, rubberBand, grid, state, callbacks }) {
   _rubberBand = rubberBand;
   _grid       = grid;
@@ -98,6 +104,17 @@ function _onStart(e) {
 
 function _onMove(e) {
   if (!rbActive) return;
+  _lastMoveEvent = e;
+  if (!_rafPending) {
+    _rafPending = true;
+    requestAnimationFrame(_processMove);
+  }
+}
+
+function _processMove() {
+  _rafPending = false;
+  const e = _lastMoveEvent;
+  if (!rbActive || !e) return;
 
   const left   = Math.min(rbStartX, e.clientX);
   const top    = Math.min(rbStartY, e.clientY);
@@ -110,11 +127,11 @@ function _onMove(e) {
   });
 
   const sel = { left, top, right: left + width, bottom: top + height };
+  const preserve = e.shiftKey || e.ctrlKey || e.metaKey;
   Array.from(_grid.children).forEach((card, i) => {
     const r = card.getBoundingClientRect();
     const overlaps = !(r.right < sel.left || r.left > sel.right ||
                        r.bottom < sel.top  || r.top  > sel.bottom);
-    const preserve = e.shiftKey || e.ctrlKey || e.metaKey;
     if (overlaps) {
       _state.selectedIdxs.add(i);
     } else if (!preserve) {
diff --git a/src/renderer/rename.js b/src/renderer/rename.js
index 3d4099b..4980a93 100644
--- a/src/renderer/rename.js
+++ b/src/renderer/rename.js
@@ -35,7 +35,11 @@ export async function doRename() {
     });
     const conflicting = newNames.filter(n => unselectedNames.has(n));
     if (conflicting.length) {
-      renameConflictList.innerHTML = conflicting.map(n => `<li>${n}</li>`).join('');
+      renameConflictList.replaceChildren(...conflicting.map(n => {
+        const li = document.createElement('li');
+        li.textContent = n;
+        return li;
+      }));
       renameConflictModal.style.display = 'flex';
       return;
     }
diff --git a/src/renderer/renderer.js b/src/renderer/renderer.js
index d705c14..060ba41 100644
--- a/src/renderer/renderer.js
+++ b/src/renderer/renderer.js
@@ -12,6 +12,8 @@ import * as dragDrop        from './handlers/drag-drop.js';
 import * as hoverPreview    from './handlers/image-preview.js';
 import * as fileExplorer    from './handlers/file-explorer.js';
 
+let _homeDir = null;
+
 // ── DOM ──────────────────────────────────────────────
 const btnOpen          = document.getElementById('btn-open');
 const btnSortName      = document.getElementById('btn-sort-name');
@@ -48,6 +50,7 @@ window.api.onFullscreenChange((isFullscreen) => {
     window.api.getHomeDir(),
     window.api.getPreviewOn(),
   ]);
+  _homeDir = homeDir;
 
   btnPreviewToggle.classList.toggle('active', previewOn);
   hoverPreview.setEnabled(previewOn);
@@ -85,7 +88,7 @@ document.addEventListener('keydown', (e) => {
 async function openFolder() {
   const folder = await window.api.selectFolder();
   if (!folder) return;
-  const homeDir = await window.api.getHomeDir();
+  const homeDir = _homeDir;
   if (folder.startsWith(homeDir)) {
     await fileExplorer.loadTree(homeDir, folder);
   } else {
diff --git a/src/renderer/style.css b/src/renderer/style.css
index bbf316d..b620785 100644
--- a/src/renderer/style.css
+++ b/src/renderer/style.css
@@ -474,6 +474,10 @@ footer span { font-size: 11px; color: var(--muted); }
   border-left: 1px solid rgba(255,255,255,.05);
   margin-left: 15px;
 }
+.tree-access-error {
+  font-size: 11px; color: var(--muted); opacity: .5;
+  padding: 2px 8px; font-style: italic;
+}
 
 /* ── 폴더 드롭 타겟 하이라이트 ── */
 .tree-row.drop-target {