feat: add welcome view, fix duplicate seeding, add star/delete UI

- Replace editable intro note with a static read-only WelcomeView component
- Add "使用指南" sidebar nav item always pointing to WelcomeView
- Fix React StrictMode double-seed race condition via module-level Promise singleton
- Add deduplicateDB() to clean up already-inserted duplicates on startup
- Add star button in editor title bar and sidebar note hover row
- Add visible delete button on note item hover in sidebar
- Default activeNoteId to '__welcome__' sentinel; deleted notes return to WelcomeView

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/App.tsx

@@ -2,7 +2,7 @@ import { useEffect } from 'react'
 import { Sidebar } from './components/sidebar/Sidebar'
 import { Editor } from './components/editor/Editor'
 import { useAppStore } from './stores/appStore'
-import { seedIfEmpty } from './db'
+import { seedIfEmpty, deduplicateDB } from './db'
 
 export default function App() {
   const { loadAll, theme } = useAppStore()
@@ -12,7 +12,9 @@ export default function App() {
   }, [theme])
 
   useEffect(() => {
-    seedIfEmpty().then(() => loadAll())
+    seedIfEmpty()
+      .then(() => deduplicateDB())
+      .then(() => loadAll())
   }, [])
 
   return (

src/components/editor/Editor.tsx

@@ -8,6 +8,7 @@ import TaskList from '@tiptap/extension-task-list'
 import TaskItem from '@tiptap/extension-task-item'
 import { Table } from '@tiptap/extension-table'
 import TableRow from '@tiptap/extension-table-row'
+import { WelcomeView } from './WelcomeView'
 import TableCell from '@tiptap/extension-table-cell'
 import TableHeader from '@tiptap/extension-table-header'
 import CharacterCount from '@tiptap/extension-character-count'
@@ -19,7 +20,7 @@ import {
   Bold, Italic, Underline as UnderlineIcon, Strikethrough, Code,
   Highlighter, List, ListOrdered, Quote,
   Heading1, Heading2, Heading3, Minus, CheckSquare, Table as TableIcon,
-  Type,
+  Type, Star,
 } from 'lucide-react'
 import { useAppStore } from '../../stores/appStore'
 import { countWords } from '../../lib/utils'
@@ -66,7 +67,7 @@ function SlashMenu({ items, selectedIndex, onSelect }: {
 }
 
 export function Editor() {
-  const { activeNoteId, notes, updateNote } = useAppStore()
+  const { activeNoteId, notes, updateNote, toggleStar } = useAppStore()
   const activeNote = notes.find(n => n.id === activeNoteId)
 
   const [title, setTitle] = useState(activeNote?.title ?? '')
@@ -219,28 +220,35 @@ export function Editor() {
     }, 500)
   }
 
-  if (!activeNote) {
-    return (
-      <div className="flex-1 flex items-center justify-center" style={{ color: 'var(--text-faint)' }}>
-        <div className="text-center">
-          <div className="text-5xl mb-4 opacity-20">✏️</div>
-          <p className="text-base">选择一篇笔记，或创建新笔记</p>
-        </div>
-      </div>
-    )
+  if (!activeNote || activeNoteId === '__welcome__') {
+    return <WelcomeView />
   }
 
   return (
     <div className="flex-1 flex flex-col min-w-0 h-full" style={{ background: 'var(--bg)' }}>
       {/* Title */}
       <div className="px-12 pt-10 pb-0 max-w-3xl mx-auto w-full">
-        <input
-          value={title}
-          onChange={e => handleTitleChange(e.target.value)}
-          placeholder="无标题"
-          className="w-full bg-transparent outline-none text-3xl font-bold"
-          style={{ color: 'var(--text)', letterSpacing: '-0.02em' }}
-        />
+        <div className="flex items-start gap-3">
+          <input
+            value={title}
+            onChange={e => handleTitleChange(e.target.value)}
+            placeholder="无标题"
+            className="flex-1 bg-transparent outline-none text-3xl font-bold min-w-0"
+            style={{ color: 'var(--text)', letterSpacing: '-0.02em' }}
+          />
+          <button
+            onClick={() => activeNoteId && toggleStar(activeNoteId)}
+            title={activeNote.starred ? '取消收藏' : '收藏'}
+            className="toolbar-btn shrink-0 mt-2"
+            style={{ width: 28, height: 28 }}
+          >
+            <Star
+              size={16}
+              fill={activeNote.starred ? '#f59e0b' : 'none'}
+              style={{ color: activeNote.starred ? '#f59e0b' : 'var(--text-faint)' }}
+            />
+          </button>
+        </div>
       </div>
 
       {/* Floating bubble menu rendered via portal */}

src/components/editor/WelcomeView.tsx

@@ -0,0 +1,176 @@
+import {
+  FileText, Folder, Slash, MousePointer, Save,
+  Search, Moon, Plus, Hash,
+} from 'lucide-react'
+import { useAppStore } from '../../stores/appStore'
+
+const FEATURES = [
+  {
+    icon: <FileText size={18} />,
+    title: '富文本编辑',
+    desc: '标题、列表、引用、代码块、表格、任务清单，应有尽有',
+  },
+  {
+    icon: <Slash size={18} />,
+    title: '斜杠命令',
+    desc: '输入 / 唤出命令菜单，用键盘快速插入任意内容块',
+  },
+  {
+    icon: <MousePointer size={18} />,
+    title: '浮动工具栏',
+    desc: '选中文字后浮现格式工具栏，点击即可加粗、高亮、转标题',
+  },
+  {
+    icon: <Save size={18} />,
+    title: '自动保存',
+    desc: '停止输入 1 秒后自动写入本地 IndexedDB，无需手动保存',
+  },
+  {
+    icon: <Folder size={18} />,
+    title: '文件夹管理',
+    desc: '创建多级文件夹，右键可重命名或删除，拖拽随意整理',
+  },
+  {
+    icon: <Search size={18} />,
+    title: '全文搜索',
+    desc: '侧边栏搜索框实时过滤笔记标题和标签',
+  },
+  {
+    icon: <Hash size={18} />,
+    title: '标签系统',
+    desc: '为笔记添加多个标签，跨文件夹快速定位相关内容',
+  },
+  {
+    icon: <Moon size={18} />,
+    title: '深色模式',
+    desc: '点击左上角图标一键切换亮色 / 暗色主题',
+  },
+]
+
+const SHORTCUTS = [
+  { keys: ['⌘', 'B'], desc: '粗体' },
+  { keys: ['⌘', 'I'], desc: '斜体' },
+  { keys: ['⌘', 'U'], desc: '下划线' },
+  { keys: ['⌘', 'Z'], desc: '撤销' },
+  { keys: ['/'], desc: '命令菜单' },
+]
+
+export function WelcomeView() {
+  const { createNote } = useAppStore()
+
+  return (
+    <div
+      className="flex-1 overflow-y-auto h-full"
+      style={{ background: 'var(--bg)' }}
+    >
+      <div className="max-w-2xl mx-auto px-12 pt-16 pb-20">
+
+        {/* Hero */}
+        <div className="mb-12">
+          <div
+            className="inline-flex items-center justify-center w-14 h-14 rounded-2xl mb-6 text-2xl"
+            style={{ background: 'var(--accent-subtle)', color: 'var(--accent)' }}
+          >
+            ✏️
+          </div>
+          <h1
+            className="text-4xl font-bold mb-3"
+            style={{ color: 'var(--text)', letterSpacing: '-0.03em', lineHeight: 1.15 }}
+          >
+            欢迎使用笔记
+          </h1>
+          <p className="text-base" style={{ color: 'var(--text-muted)', lineHeight: 1.7 }}>
+            一款基于 Vite + React + TipTap 构建的现代笔记应用。
+            <br />
+            点击左侧笔记开始阅读，或新建一篇属于你的笔记。
+          </p>
+          <button
+            onClick={() => createNote(null)}
+            className="inline-flex items-center gap-2 mt-6 px-4 py-2 rounded-lg text-sm font-medium transition-colors"
+            style={{
+              background: 'var(--accent)',
+              color: '#fff',
+            }}
+            onMouseEnter={e => (e.currentTarget.style.background = 'var(--accent-hover)')}
+            onMouseLeave={e => (e.currentTarget.style.background = 'var(--accent)')}
+          >
+            <Plus size={15} />
+            新建笔记
+          </button>
+        </div>
+
+        {/* Divider */}
+        <div style={{ borderTop: '1px solid var(--border)', marginBottom: '2.5rem' }} />
+
+        {/* Features */}
+        <h2
+          className="text-xs font-semibold uppercase tracking-widest mb-5"
+          style={{ color: 'var(--text-faint)' }}
+        >
+          功能一览
+        </h2>
+        <div className="grid grid-cols-2 gap-3 mb-12">
+          {FEATURES.map(f => (
+            <div
+              key={f.title}
+              className="rounded-xl p-4"
+              style={{ background: 'var(--bg-subtle)', border: '1px solid var(--border)' }}
+            >
+              <div
+                className="inline-flex items-center justify-center w-8 h-8 rounded-lg mb-3"
+                style={{ background: 'var(--accent-subtle)', color: 'var(--accent)' }}
+              >
+                {f.icon}
+              </div>
+              <div className="text-sm font-semibold mb-1" style={{ color: 'var(--text)' }}>{f.title}</div>
+              <div className="text-xs leading-relaxed" style={{ color: 'var(--text-muted)' }}>{f.desc}</div>
+            </div>
+          ))}
+        </div>
+
+        {/* Shortcuts */}
+        <h2
+          className="text-xs font-semibold uppercase tracking-widest mb-4"
+          style={{ color: 'var(--text-faint)' }}
+        >
+          常用快捷键
+        </h2>
+        <div
+          className="rounded-xl overflow-hidden"
+          style={{ border: '1px solid var(--border)' }}
+        >
+          {SHORTCUTS.map((s, i) => (
+            <div
+              key={s.desc}
+              className="flex items-center justify-between px-5 py-3"
+              style={{
+                borderTop: i > 0 ? '1px solid var(--border)' : 'none',
+                background: 'var(--bg-subtle)',
+              }}
+            >
+              <span className="text-sm" style={{ color: 'var(--text-muted)' }}>{s.desc}</span>
+              <div className="flex items-center gap-1">
+                {s.keys.map(k => (
+                  <kbd
+                    key={k}
+                    className="inline-flex items-center justify-center px-2 py-0.5 rounded text-xs font-mono"
+                    style={{
+                      background: 'var(--bg)',
+                      border: '1px solid var(--border)',
+                      color: 'var(--text)',
+                      minWidth: 28,
+                      boxShadow: '0 1px 0 var(--border)',
+                    }}
+                  >
+                    {k}
+                  </kbd>
+                ))}
+              </div>
+            </div>
+          ))}
+        </div>
+
+      </div>
+    </div>
+  )
+}

src/components/sidebar/Sidebar.tsx

@@ -2,18 +2,18 @@ import { useState, useRef, useEffect } from 'react'
 import {
   Search, Plus, Star, FileText, Folder, FolderOpen,
   ChevronRight, ChevronDown,
-  Trash2, Edit2, Moon, Sun, FolderPlus, Hash,
+  Trash2, Edit2, Moon, Sun, FolderPlus, Hash, BookOpen,
 } from 'lucide-react'
 import { useAppStore } from '../../stores/appStore'
 import { formatDate } from '../../lib/utils'
-import type { Folder as FolderType } from '../../db'
+import type { Folder as FolderType, Note } from '../../db'
 
 export function Sidebar() {
   const {
     notes, folders, activeNoteId, activeFolderId, searchQuery,
     theme, createNote, createFolder, deleteNote, deleteFolder,
     updateFolder, setActiveNote, setActiveFolder, setSearch,
-    toggleTheme, filteredNotes,
+    toggleTheme, toggleStar, filteredNotes,
   } = useAppStore()
 
   const [expandedFolders, setExpandedFolders] = useState<Set<string>>(new Set())
@@ -117,8 +117,9 @@ export function Sidebar() {
 
       {/* Nav shortcuts */}
       <nav className="px-2 space-y-0.5">
-        <NavItem icon={<FileText size={14} />} label="所有笔记" count={notes.length} active={activeFolderId === 'all'} onClick={() => setActiveFolder('all')} />
-        <NavItem icon={<Star size={14} />} label="收藏" count={notes.filter(n => n.starred).length} active={activeFolderId === 'starred'} onClick={() => setActiveFolder('starred')} />
+        <NavItem icon={<BookOpen size={14} />} label="使用指南" active={activeNoteId === '__welcome__'} onClick={() => setActiveNote('__welcome__')} />
+        <NavItem icon={<FileText size={14} />} label="所有笔记" count={notes.length} active={activeFolderId === 'all' && activeNoteId !== '__welcome__'} onClick={() => { setActiveFolder('all'); if (activeNoteId === '__welcome__') setActiveNote(null) }} />
+        <NavItem icon={<Star size={14} />} label="收藏" count={notes.filter(n => n.starred).length} active={activeFolderId === 'starred'} onClick={() => { setActiveFolder('starred'); if (activeNoteId === '__welcome__') setActiveNote(null) }} />
       </nav>
 
       {/* Folders section */}
@@ -190,38 +191,18 @@ export function Sidebar() {
             </div>
           )}
           {displayed.map(note => (
-            <div
+            <NoteItem
               key={note.id}
-              className="px-2 py-2 rounded-lg cursor-pointer"
-              style={{
-                background: activeNoteId === note.id ? 'var(--accent-subtle)' : 'transparent',
-                borderLeft: activeNoteId === note.id ? '2px solid var(--accent)' : '2px solid transparent',
-              }}
+              note={note}
+              active={activeNoteId === note.id}
               onClick={() => setActiveNote(note.id)}
+              onDelete={() => deleteNote(note.id)}
+              onToggleStar={() => toggleStar(note.id)}
               onContextMenu={(e) => {
                 e.preventDefault()
                 setContextMenu({ type: 'note', id: note.id, x: e.clientX, y: e.clientY })
               }}
-            >
-              <div className="flex items-start justify-between gap-1">
-                <div className="flex items-center gap-1.5 min-w-0">
-                  {note.starred && <Star size={11} style={{ color: '#f59e0b', flexShrink: 0 }} fill="currentColor" />}
-                  <span className="text-sm font-medium truncate" style={{ color: activeNoteId === note.id ? 'var(--accent)' : 'var(--text)' }}>
-                    {note.title || '无标题笔记'}
-                  </span>
-                </div>
-                <span className="text-xs shrink-0 mt-0.5" style={{ color: 'var(--text-faint)' }}>{formatDate(note.updatedAt)}</span>
-              </div>
-              {note.tags.length > 0 && (
-                <div className="flex gap-1 mt-1 flex-wrap">
-                  {note.tags.slice(0, 3).map(tag => (
-                    <span key={tag} className="inline-flex items-center gap-0.5 text-xs px-1.5 py-0.5 rounded-full" style={{ background: 'var(--bg-muted)', color: 'var(--text-muted)' }}>
-                      <Hash size={9} />{tag}
-                    </span>
-                  ))}
-                </div>
-              )}
-            </div>
+            />
           ))}
         </div>
       </div>
@@ -304,3 +285,73 @@ function CtxItem({ icon, label, danger, onClick }: { icon: React.ReactNode; labe
     </button>
   )
 }
+
+function NoteItem({ note, active, onClick, onDelete, onToggleStar, onContextMenu }: {
+  note: Note
+  active: boolean
+  onClick: () => void
+  onDelete: () => void
+  onToggleStar: () => void
+  onContextMenu: (e: React.MouseEvent) => void
+}) {
+  const [hovered, setHovered] = useState(false)
+
+  return (
+    <div
+      className="px-2 py-2 rounded-lg cursor-pointer relative"
+      style={{
+        background: active ? 'var(--accent-subtle)' : hovered ? 'var(--bg-muted)' : 'transparent',
+        borderLeft: active ? '2px solid var(--accent)' : '2px solid transparent',
+      }}
+      onClick={onClick}
+      onContextMenu={onContextMenu}
+      onMouseEnter={() => setHovered(true)}
+      onMouseLeave={() => setHovered(false)}
+    >
+      <div className="flex items-start justify-between gap-1">
+        <div className="flex items-center gap-1.5 min-w-0 flex-1">
+          {note.starred && <Star size={11} style={{ color: '#f59e0b', flexShrink: 0 }} fill="currentColor" />}
+          <span className="text-sm font-medium truncate" style={{ color: active ? 'var(--accent)' : 'var(--text)' }}>
+            {note.title || '无标题笔记'}
+          </span>
+        </div>
+        {hovered ? (
+          <div className="flex items-center gap-0.5 shrink-0">
+            <button
+              className="toolbar-btn"
+              style={{ width: 20, height: 20, color: note.starred ? '#f59e0b' : 'var(--text-faint)' }}
+              title={note.starred ? '取消收藏' : '收藏'}
+              onClick={(e) => { e.stopPropagation(); onToggleStar() }}
+            >
+              <Star size={12} fill={note.starred ? '#f59e0b' : 'none'} />
+            </button>
+            <button
+              className="toolbar-btn"
+              style={{ width: 20, height: 20, color: '#ef4444', opacity: 0.8 }}
+              title="删除笔记"
+              onClick={(e) => { e.stopPropagation(); onDelete() }}
+              onMouseEnter={e => (e.currentTarget.style.opacity = '1')}
+              onMouseLeave={e => (e.currentTarget.style.opacity = '0.8')}
+            >
+              <Trash2 size={12} />
+            </button>
+          </div>
+        ) : (
+          <span className="text-xs shrink-0 mt-0.5" style={{ color: 'var(--text-faint)' }}>
+            {formatDate(note.updatedAt)}
+          </span>
+        )}
+      </div>
+      {note.tags.length > 0 && (
+        <div className="flex gap-1 mt-1 flex-wrap">
+          {note.tags.slice(0, 3).map(tag => (
+            <span key={tag} className="inline-flex items-center gap-0.5 text-xs px-1.5 py-0.5 rounded-full"
+              style={{ background: 'var(--bg-muted)', color: 'var(--text-muted)' }}>
+              <Hash size={9} />{tag}
+            </span>
+          ))}
+        </div>
+      )}
+    </div>
+  )
+}

src/db/index.ts

@@ -43,7 +43,15 @@ class NotesDB extends Dexie {
 
 export const db = new NotesDB()
 
-export async function seedIfEmpty() {
+// Module-level singleton prevents double-seeding under React StrictMode
+let _seedPromise: Promise<void> | null = null
+
+export function seedIfEmpty(): Promise<void> {
+  if (!_seedPromise) _seedPromise = _doSeed()
+  return _seedPromise
+}
+
+async function _doSeed() {
   const count = await db.notes.count()
   if (count > 0) return
 
@@ -57,34 +65,6 @@ export async function seedIfEmpty() {
   ])
 
   await db.notes.bulkAdd([
-    {
-      id: crypto.randomUUID(),
-      title: '欢迎使用笔记应用',
-      content: JSON.stringify({
-        type: 'doc',
-        content: [
-          { type: 'heading', attrs: { level: 1 }, content: [{ type: 'text', text: '欢迎使用 ✨' }] },
-          { type: 'paragraph', content: [{ type: 'text', text: '这是一款基于 Vite + React + TipTap 构建的现代笔记应用。' }] },
-          { type: 'heading', attrs: { level: 2 }, content: [{ type: 'text', text: '功能特性' }] },
-          { type: 'bulletList', content: [
-            { type: 'listItem', content: [{ type: 'paragraph', content: [{ type: 'text', text: '支持富文本编辑（标题、列表、代码块、引用等）' }] }] },
-            { type: 'listItem', content: [{ type: 'paragraph', content: [{ type: 'text', text: '输入 / 呼出斜杠命令菜单' }] }] },
-            { type: 'listItem', content: [{ type: 'paragraph', content: [{ type: 'text', text: '选中文字查看浮动工具栏' }] }] },
-            { type: 'listItem', content: [{ type: 'paragraph', content: [{ type: 'text', text: '自动保存到 IndexedDB' }] }] },
-            { type: 'listItem', content: [{ type: 'paragraph', content: [{ type: 'text', text: '文件夹分类管理' }] }] },
-          ]},
-          { type: 'heading', attrs: { level: 2 }, content: [{ type: 'text', text: '代码示例' }] },
-          { type: 'codeBlock', attrs: { language: 'typescript' }, content: [{ type: 'text', text: 'const hello = "Hello, World!"\nconsole.log(hello)' }] },
-          { type: 'blockquote', content: [{ type: 'paragraph', content: [{ type: 'text', text: '好记性不如烂笔头。开始记录你的想法吧！' }] }] },
-        ],
-      }),
-      folderId: null,
-      tags: ['入门'],
-      starred: true,
-      createdAt: now,
-      updatedAt: now,
-      wordCount: 80,
-    },
     {
       id: crypto.randomUUID(),
       title: '项目计划',
@@ -127,3 +107,44 @@ export async function seedIfEmpty() {
     },
   ])
 }
+
+// Removes duplicate folders and notes inserted by React StrictMode double-mount.
+// Groups by (name + parentId) for folders, (title + createdAt bucket) for notes.
+export async function deduplicateDB() {
+  // --- folders ---
+  const allFolders = await db.folders.toArray()
+  const folderSeen = new Map<string, string>() // key → keep id
+  const folderRemap = new Map<string, string>() // deleted id → kept id
+
+  for (const f of allFolders) {
+    const key = `${f.parentId ?? ''}::${f.name}`
+    if (!folderSeen.has(key)) {
+      folderSeen.set(key, f.id)
+    } else {
+      folderRemap.set(f.id, folderSeen.get(key)!)
+      await db.folders.delete(f.id)
+    }
+  }
+
+  // Re-point notes that referenced a deleted folder
+  if (folderRemap.size > 0) {
+    const notesToFix = await db.notes.filter(n => n.folderId !== null && folderRemap.has(n.folderId!)).toArray()
+    for (const n of notesToFix) {
+      await db.notes.update(n.id, { folderId: folderRemap.get(n.folderId!)! })
+    }
+  }
+
+  // --- notes: deduplicate by title + createdAt within 2 s window ---
+  const allNotes = await db.notes.toArray()
+  const noteSeen = new Map<string, number>() // key → kept createdAt
+
+  for (const n of allNotes) {
+    const bucket = Math.floor(n.createdAt / 2000)
+    const key = `${n.title}::${bucket}`
+    if (!noteSeen.has(key)) {
+      noteSeen.set(key, n.createdAt)
+    } else {
+      await db.notes.delete(n.id)
+    }
+  }
+}

src/stores/appStore.ts

@@ -32,7 +32,7 @@ interface AppState {
 export const useAppStore = create<AppState>((set, get) => ({
   notes: [],
   folders: [],
-  activeNoteId: null,
+  activeNoteId: '__welcome__' as string | null,
   activeFolderId: 'all',
   searchQuery: '',
   theme: (localStorage.getItem('theme') as 'light' | 'dark') || 'light',
@@ -43,8 +43,10 @@ export const useAppStore = create<AppState>((set, get) => ({
       db.folders.orderBy('order').toArray(),
     ])
     set({ notes, folders })
-    if (notes.length > 0 && !get().activeNoteId) {
-      set({ activeNoteId: notes[0].id })
+    // Keep welcome screen as default; only auto-select if already on a real note
+    const cur = get().activeNoteId
+    if (cur && cur !== '__welcome__' && !notes.find(n => n.id === cur)) {
+      set({ activeNoteId: '__welcome__' })
     }
   },
 
@@ -81,7 +83,7 @@ export const useAppStore = create<AppState>((set, get) => ({
     await db.notes.delete(id)
     set(s => {
       const notes = s.notes.filter(n => n.id !== id)
-      const activeNoteId = s.activeNoteId === id ? (notes[0]?.id ?? null) : s.activeNoteId
+      const activeNoteId = s.activeNoteId === id ? '__welcome__' : s.activeNoteId
       return { notes, activeNoteId }
     })
   },