diff --git a/docs/17-sidebar-fixes.md b/docs/17-sidebar-fixes.md
new file mode 100644
index 0000000..e92b9eb
--- /dev/null
+++ b/docs/17-sidebar-fixes.md
@@ -0,0 +1,33 @@
+# 侧边栏四项反馈处理（2026-11-14）
+
+对应大王截图反馈：①「打开文件夹」按钮偏了 ②没进上次打开的文件夹 ③没有下级文件夹 ④不能在文件夹下新建文件夹和文档。验证：tsc 0 错误、vitest **86 通过 + 2 跳过**（新增文件树回归 3 例）、build 通过。
+
+## ① 按钮偏移
+
+空状态区（.sidebar-empty）改为与页签行一致的 10px 左缩进、纵向 flex 左对齐排布，段落默认外边距清零，按钮与上方文字左缘对齐、不再贴边/溢出。
+
+## ② 启动自动恢复上次工作区
+
+原先只把打开过的工作区写进历史表、启动时从不读回。现：打开文件夹时把路径存入偏好（lastWorkspace）；启动初始化时读回并校验文件夹仍存在（statFile），存在就自动设为工作区根。不新增 Rust 命令（复用 prefs 通道），Web 模式走 localStorage 同构。
+
+## ③ 下级文件夹
+
+实测结论先说清：**当前代码的文件树本来就支持逐级展开**——专门写了组件级测试（mock 目录数据）验证：文件夹行带 ▸，点击展开能看到下级 .md，逻辑没有缺陷。用户当时看不到下级，最可能两种情况：测试时跑的构建较旧；或子文件夹里没有 .md/.markdown/.txt 文件——文件树按设计只收这三类文档，其余文件不显示，展开后就是空白，容易误读为「没有下级」。
+
+本次做的改进是把反馈做明确，避免再误读：
+- 展开后的空文件夹显示一行「（空）」而不是空白；
+- 文件夹行加粗区分，▸/▾ 展开箭头保留。
+
+## ④ 在任意文件夹下新建
+
+- 树头两个按钮：「＋ 文档」「＋ 文件夹」，作用于工作区根目录；
+- 文件夹右键菜单新增「在此新建文档…」「在此新建文件夹…」，作用于该文件夹；
+- 新建文档沿用原逻辑（补 .md、重名报错不覆盖、建完自动打开）；新建文件夹校验名字（不能为空、不能含 Windows 非法字符），建完刷新树并提示。
+- 实现：App 的 createFileInWorkspace 泛化为 createFileInDir(dir)，新增 createFolderInDir(dir)（走既有 createDirPath 命令）。
+
+## 复验建议（Windows）
+
+- 重启应用：应直接进上次的文件夹，文件树就位。
+- 点开任意子文件夹：有文档的显示文档，没有的显示「（空）」。
+- 右键一个子文件夹 → 在此新建文档/文件夹：建完树里立刻出现，新文档自动打开。
+- 关掉工作区（或新装首次）看空状态：按钮与「尚未打开文件夹。」文字左缘对齐。
diff --git a/src/App.tsx b/src/App.tsx
index 729f787..ced895d 100644
--- a/src/App.tsx
+++ b/src/App.tsx
@@ -26,7 +26,7 @@ import {
   isTauri, pickOpenFile, pickSaveFile, pickFolder, readTextFile, writeTextFile,
   pickAndReadWebFile, downloadTextFile,
   pickImageFile, pickAnyFile, pickAndReadWebImage, copyToAssets, saveBytesToAssets, fileToBase64,
-  statFile, createTextFile, renamePath, deleteToTrash, type DirEntry, type RecoveryEntry,
+  statFile, createTextFile, createDirPath, renamePath, deleteToTrash, type DirEntry, type RecoveryEntry,
   pickSaveHtmlFile, pickImportFile, readFileBase64, readBinaryFile, pickAndReadWebImport,
 } from './services/platform'
 import * as store from './services/store'
@@ -423,6 +423,13 @@ export default function App() {
       uiLoadedRef.current = true
       const recentFromDb = await store.loadRecent()
       if (!cancelled && recentFromDb) setRecent(recentFromDb.map((r) => r.path))
+      // 工作区恢复：自动回到上次打开的文件夹（文件夹已不存在则跳过）
+      const lastWs = await store.loadLastWorkspace()
+      if (!cancelled && lastWs) {
+        try {
+          if ((await statFile(lastWs)).exists) setWorkspaceRoot(lastWs)
+        } catch { /* 已删除/不可达时不恢复 */ }
+      }
       // 启动恢复：先读磁盘现状再划分（与磁盘一致的记录静默清理）
       const records = await store.listRecovery()
       if (!cancelled && records.length > 0) {
@@ -447,7 +454,10 @@ export default function App() {
   }, [])
 
   useEffect(() => {
-    if (workspaceRoot) store.addWorkspace(workspaceRoot)
+    if (workspaceRoot) {
+      store.addWorkspace(workspaceRoot)
+      store.saveLastWorkspace(workspaceRoot)
+    }
   }, [workspaceRoot])
 
   // ——— 阶段 4：标签关闭后清理基线与恢复记录 ———
@@ -576,14 +586,13 @@ export default function App() {
     Boolean(a && b && a.replace(/\\/g, '/') === b.replace(/\\/g, '/'))
   const dirOf = (path: string) => path.replace(/[\\/][^\\/]*$/, '')
 
-  const createFileInWorkspace = useCallback(() => {
-    if (!workspaceRoot) return
+  const createFileInDir = useCallback((dir: string) => {
     setPromptSpec({
-      title: '在工作区新建文档', label: '文件名', initial: '未命名.md',
+      title: '新建文档', label: '文件名', initial: '未命名.md',
       submit: (name) => {
         setPromptSpec(null)
         const fileName = /\.(md|markdown|txt)$/i.test(name) ? name : `${name}.md`
-        const path = joinPath(workspaceRoot, fileName)
+        const path = joinPath(dir, fileName)
         void (async () => {
           try {
             await createTextFile(path)
@@ -593,7 +602,29 @@ export default function App() {
         })()
       },
     })
-  }, [workspaceRoot, openPath])
+  }, [openPath ])
+
+  const createFolderInDir = useCallback((dir: string) => {
+    setPromptSpec({
+      title: '新建文件夹', label: '文件夹名', initial: '新文件夹',
+      submit: (name) => {
+        setPromptSpec(null)
+        const trimmed = name.trim()
+        if (!trimmed || /[\\/:*?"<>|]/.test(trimmed)) {
+          setError('文件夹名不合法：不能为空，也不能包含 \\ / : * ? " < > |')
+          return
+        }
+        const path = joinPath(dir, trimmed)
+        void (async () => {
+          try {
+            await createDirPath(path)
+            setTreeRefresh((n) => n + 1)
+            flash(`已新建文件夹：${trimmed}`)
+          } catch (e) { setError(String(e)) }
+        })()
+      },
+    })
+  }, [flash])
 
   const renameEntry = useCallback((entry: DirEntry) => {
     setPromptSpec({
@@ -1116,7 +1147,8 @@ export default function App() {
               activePath={tab?.path ?? null}
               onOpenFile={handleSidebarOpenFile}
               onOpenFolder={handleSidebarOpenFolder}
-              onCreateFile={tauriMode && workspaceRoot ? createFileInWorkspace : undefined}
+              onCreateFileIn={tauriMode && workspaceRoot ? createFileInDir : undefined}
+              onCreateFolderIn={tauriMode && workspaceRoot ? createFolderInDir : undefined}
               onRenameEntry={tauriMode ? renameEntry : undefined}
               onDeleteEntry={tauriMode ? deleteEntry : undefined}
               refreshSignal={treeRefresh}
diff --git a/src/components/Sidebar.tsx b/src/components/Sidebar.tsx
index 898c3f5..2b3c57c 100644
--- a/src/components/Sidebar.tsx
+++ b/src/components/Sidebar.tsx
@@ -11,7 +11,8 @@ interface Props {
   activePath: string | null
   onOpenFile: (path: string) => void
   onOpenFolder: () => void
-  onCreateFile?: () => void
+  onCreateFileIn?: (dir: string) => void
+  onCreateFolderIn?: (dir: string) => void
   onRenameEntry?: (entry: DirEntry) => void
   onDeleteEntry?: (entry: DirEntry) => void
   refreshSignal?: number
@@ -51,7 +52,8 @@ function Sidebar(p: Props) {
           root={p.workspaceRoot}
           activePath={p.activePath}
           onOpenFile={p.onOpenFile}
-          onCreateFile={p.onCreateFile}
+          onCreateFileIn={p.onCreateFileIn}
+          onCreateFolderIn={p.onCreateFolderIn}
           onRenameEntry={p.onRenameEntry}
           onDeleteEntry={p.onDeleteEntry}
           refreshSignal={p.refreshSignal ?? 0}
@@ -68,11 +70,12 @@ function Sidebar(p: Props) {
   )
 }
 
-function FileTree({ root, activePath, onOpenFile, onCreateFile, onRenameEntry, onDeleteEntry, refreshSignal }: {
+function FileTree({ root, activePath, onOpenFile, onCreateFileIn, onCreateFolderIn, onRenameEntry, onDeleteEntry, refreshSignal }: {
   root: string
   activePath: string | null
   onOpenFile: (path: string) => void
-  onCreateFile?: () => void
+  onCreateFileIn?: (dir: string) => void
+  onCreateFolderIn?: (dir: string) => void
   onRenameEntry?: (entry: DirEntry) => void
   onDeleteEntry?: (entry: DirEntry) => void
   refreshSignal: number
@@ -92,7 +95,8 @@ function FileTree({ root, activePath, onOpenFile, onCreateFile, onRenameEntry, o
     <div className="filetree">
       <div className="filetree-head">
         <span className="filetree-root" title={root}>{baseName(root)}</span>
-        {onCreateFile && <button aria-label="新建文档" title="在工作区新建文档" onClick={onCreateFile}>＋</button>}
+        {onCreateFileIn && <button className="filetree-add" title="在工作区根目录新建文档" onClick={() => onCreateFileIn(root)}>＋ 文档</button>}
+        {onCreateFolderIn && <button className="filetree-add" title="在工作区根目录新建文件夹" onClick={() => onCreateFolderIn(root)}>＋ 文件夹</button>}
         <button aria-label="刷新目录" onClick={() => setRefreshKey((k) => k + 1)}>⟳</button>
       </div>
       <TreeLevel
@@ -102,6 +106,8 @@ function FileTree({ root, activePath, onOpenFile, onCreateFile, onRenameEntry, o
       {menu && (
         <div className="tree-context-menu" style={{ left: menu.x, top: menu.y }} onClick={(e) => e.stopPropagation()}>
           {!menu.entry.isDir && <button onClick={() => { onOpenFile(menu.entry.path); setMenu(null) }}>打开</button>}
+          {menu.entry.isDir && onCreateFileIn && <button onClick={() => { onCreateFileIn(menu.entry.path); setMenu(null) }}>在此新建文档…</button>}
+          {menu.entry.isDir && onCreateFolderIn && <button onClick={() => { onCreateFolderIn(menu.entry.path); setMenu(null) }}>在此新建文件夹…</button>}
           {onRenameEntry && <button onClick={() => { onRenameEntry(menu.entry); setMenu(null) }}>重命名…</button>}
           {onDeleteEntry && <button className="danger" onClick={() => { onDeleteEntry(menu.entry); setMenu(null) }}>删除到回收站</button>}
         </div>
@@ -147,10 +153,11 @@ function TreeLevel({ dir, depth, activePath, onOpenFile, refreshKey, onEntryMenu
 
   return (
     <div>
+      {entries.length === 0 && <div className="tree-empty" style={{ paddingLeft: 21 + depth * 13 }}>（空）</div>}
       {entries.map((entry) => (
         <div key={entry.path}>
           <button
-            className={`tree-item${!entry.isDir && entry.path === activePath ? ' active' : ''}`}
+            className={`tree-item${entry.isDir ? ' dir' : ''}${!entry.isDir && entry.path === activePath ? ' active' : ''}`}
             style={{ paddingLeft: 8 + depth * 13 }}
             onClick={() => (entry.isDir ? toggle(entry.path) : onOpenFile(entry.path))}
             onContextMenu={(e) => { e.preventDefault(); onEntryMenu(entry, e.clientX, e.clientY) }}
diff --git a/src/services/store.ts b/src/services/store.ts
index 43660d9..d7dc2e2 100644
--- a/src/services/store.ts
+++ b/src/services/store.ts
@@ -69,6 +69,26 @@ export function addWorkspace(path: string): void {
   if (isTauri()) void dbWorkspaceAdd(path, Date.now()).catch(() => undefined)
 }
 
+const LS_LAST_WORKSPACE = 'new-markdown:lastWorkspace'
+
+/** 记住最近一次打开的工作区（启动时自动恢复用，走 prefs/localStorage，不新增 Rust 命令）。 */
+export function saveLastWorkspace(path: string): void {
+  if (isTauri()) {
+    void dbPrefSet('lastWorkspace', path).catch(() => undefined)
+    return
+  }
+  localStorage.setItem(LS_LAST_WORKSPACE, path)
+}
+
+export async function loadLastWorkspace(): Promise<string | null> {
+  if (!isTauri()) return localStorage.getItem(LS_LAST_WORKSPACE)
+  try {
+    return await dbPrefGet('lastWorkspace')
+  } catch {
+    return null
+  }
+}
+
 export async function loadUiPref(): Promise<string | null> {
   if (!isTauri()) return null
   try {
diff --git a/src/styles.css b/src/styles.css
index 009316d..990c8b8 100644
--- a/src/styles.css
+++ b/src/styles.css
@@ -78,12 +78,16 @@ button { font: inherit; color: inherit; }
 .outline, .filetree { overflow-y: auto; padding: 6px 8px 16px; }
 .outline-item { display: block; width: 100%; text-align: left; border: 0; background: transparent; padding: 4px 6px; border-radius: 6px; cursor: pointer; font-size: 13px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
 .outline-item:hover { background: var(--hover); }
-.sidebar-empty { padding: 14px 12px; font-size: 13px; color: var(--text-dim); line-height: 1.6; }
+.sidebar-empty { padding: 12px 10px; font-size: 13px; color: var(--text-dim); line-height: 1.6; display: flex; flex-direction: column; align-items: flex-start; gap: 6px; }
+.sidebar-empty p { margin: 0; }
 .sidebar-action, .primary { background: var(--accent); color: #fff; border: 0; border-radius: 7px; padding: 6px 14px; cursor: pointer; }
 .filetree-head { display: flex; align-items: center; gap: 6px; padding: 2px 4px 6px; }
 .filetree-root { font-weight: 600; font-size: 13px; flex: 1; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
 .filetree-head button { border: 0; background: transparent; cursor: pointer; border-radius: 5px; color: var(--text-dim); }
 .filetree-head button:hover { background: var(--hover); }
+.filetree-add { font-size: 12px; padding: 2px 6px; white-space: nowrap; }
+.tree-item.dir { font-weight: 500; }
+.tree-empty { color: var(--text-dim); font-size: 12px; padding-top: 2px; padding-bottom: 2px; }
 .tree-item { display: flex; gap: 5px; width: 100%; text-align: left; border: 0; background: transparent; padding: 3.5px 6px; border-radius: 6px; cursor: pointer; font-size: 13px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
 .tree-item:hover { background: var(--hover); }
 .tree-item.active { background: var(--accent-weak); }
diff --git a/tests/sidebar-tree.test.tsx b/tests/sidebar-tree.test.tsx
new file mode 100644
index 0000000..9172d2d
--- /dev/null
+++ b/tests/sidebar-tree.test.tsx
@@ -0,0 +1,101 @@
+// 文件树回归：子文件夹展开、空文件夹提示、文件夹右键新建文档/文件夹。
+import { describe, it, expect, vi } from 'vitest'
+import { createRoot } from 'react-dom/client'
+import { act } from 'react-dom/test-utils'
+
+vi.mock('../src/services/platform', async (importOriginal) => {
+  const orig = await importOriginal<typeof import('../src/services/platform')>()
+  return {
+    ...orig,
+    listDir: async (dir: string) => {
+      if (dir === 'C:/ws') {
+        return [
+          { name: 'sub', path: 'C:/ws/sub', isDir: true },
+          { name: 'empty', path: 'C:/ws/empty', isDir: true },
+          { name: 'a.md', path: 'C:/ws/a.md', isDir: false },
+        ]
+      }
+      if (dir === 'C:/ws/sub') return [{ name: 'b.md', path: 'C:/ws/sub/b.md', isDir: false }]
+      return []
+    },
+  }
+})
+
+import Sidebar from '../src/components/Sidebar'
+
+const sleep = (ms: number) => new Promise((r) => setTimeout(r, ms))
+
+async function renderSidebar(extra: Record<string, unknown> = {}) {
+  const container = document.createElement('div')
+  document.body.appendChild(container)
+  const root = createRoot(container)
+  await act(async () => {
+    root.render(
+      <Sidebar
+        mode="files"
+        onModeChange={() => undefined}
+        workspaceRoot="C:/ws"
+        activePath={null}
+        onOpenFile={() => undefined}
+        onOpenFolder={() => undefined}
+        outline={[]}
+        onJumpHeading={() => undefined}
+        tauriMode
+        {...extra}
+      />,
+    )
+  })
+  await act(async () => { await sleep(30) })
+  return { container, root }
+}
+
+function findButton(container: HTMLElement, text: string) {
+  return [...container.querySelectorAll('button')].find((b) => b.textContent?.includes(text))
+}
+
+describe('文件树', () => {
+  it('子文件夹点击展开能看到下级文件', async () => {
+    const { container, root } = await renderSidebar()
+    await act(async () => {
+      findButton(container, 'sub')?.dispatchEvent(new MouseEvent('click', { bubbles: true }))
+    })
+    await act(async () => { await sleep(30) })
+    expect(container.innerHTML).toContain('b.md')
+    await act(async () => { root.unmount() })
+    container.remove()
+  })
+
+  it('空文件夹展开后有（空）提示而不是空白', async () => {
+    const { container, root } = await renderSidebar()
+    await act(async () => {
+      findButton(container, 'empty')?.dispatchEvent(new MouseEvent('click', { bubbles: true }))
+    })
+    await act(async () => { await sleep(30) })
+    expect(container.innerHTML).toContain('（空）')
+    await act(async () => { root.unmount() })
+    container.remove()
+  })
+
+  it('文件夹右键菜单有新建文档/文件夹并回传该文件夹', async () => {
+    const created: string[] = []
+    const folders: string[] = []
+    const { container, root } = await renderSidebar({
+      onCreateFileIn: (dir: string) => created.push(dir),
+      onCreateFolderIn: (dir: string) => folders.push(dir),
+    })
+    await act(async () => {
+      findButton(container, 'sub')?.dispatchEvent(new MouseEvent('contextmenu', { bubbles: true }))
+    })
+    await act(async () => { await sleep(10) })
+    const fileItem = findButton(container, '在此新建文档')
+    const folderItem = findButton(container, '在此新建文件夹')
+    expect(fileItem).toBeTruthy()
+    expect(folderItem).toBeTruthy()
+    await act(async () => {
+      fileItem?.dispatchEvent(new MouseEvent('click', { bubbles: true }))
+    })
+    expect(created).toEqual(['C:/ws/sub'])
+    await act(async () => { root.unmount() })
+    container.remove()
+  })
+})