diff --git a/memento-note/components/agents/agent-detail-view.tsx b/memento-note/components/agents/agent-detail-view.tsx
index 3c0b218..9976ebb 100644
--- a/memento-note/components/agents/agent-detail-view.tsx
+++ b/memento-note/components/agents/agent-detail-view.tsx
@@ -97,7 +97,7 @@ interface AgentDetailViewProps {
     _count: { actions: number }
     actions: { id: string; status: string; createdAt: string | Date }[]
   } | null
-  notebooks: { id: string; name: string; icon?: string | null }[]
+  notebooks: { id: string; name: string; icon?: string | null; parentId?: string | null }[]
   onSave: (data: FormData) => Promise<void>
   onBack: () => void
   onOpenLogs: (agentId: string, agentName: string) => void
@@ -494,8 +494,13 @@ export function AgentDetailView({
                           className={selectCls}
                         >
                           <option value="">{t('agents.form.selectNotebook')}</option>
-                          {notebooks.map(nb => (
-                            <option key={nb.id} value={nb.id}>{nb.name}</option>
+                          {notebooks.filter(nb => !nb.parentId).map(nb => (
+                            <optgroup key={nb.id} label={nb.name}>
+                              <option value={nb.id}>{nb.name}</option>
+                              {notebooks.filter(c => c.parentId === nb.id).map(child => (
+                                <option key={child.id} value={child.id}>  └ {child.name}</option>
+                              ))}
+                            </optgroup>
                           ))}
                         </select>
                       </div>
@@ -645,8 +650,13 @@ export function AgentDetailView({
                         <label className={labelCls}>{t('agents.form.targetNotebook')}<FieldHelp tooltip={t('agents.help.tooltips.targetNotebook')} /></label>
                         <select value={targetNotebookId} onChange={e => setTargetNotebookId(e.target.value)} className={selectCls}>
                           <option value="">{t('agents.form.inbox')}</option>
-                          {notebooks.map(nb => (
-                            <option key={nb.id} value={nb.id}>{nb.name}</option>
+                          {notebooks.filter(nb => !nb.parentId).map(nb => (
+                            <optgroup key={nb.id} label={nb.name}>
+                              <option value={nb.id}>{nb.name}</option>
+                              {notebooks.filter(c => c.parentId === nb.id).map(child => (
+                                <option key={child.id} value={child.id}>  └ {child.name}</option>
+                              ))}
+                            </optgroup>
                           ))}
                         </select>
                       </div>
diff --git a/memento-note/components/note-card.tsx b/memento-note/components/note-card.tsx
index a9d9d1b..61d9fb5 100644
--- a/memento-note/components/note-card.tsx
+++ b/memento-note/components/note-card.tsx
@@ -504,18 +504,27 @@ export const NoteCard = memo(function NoteCard({
               <StickyNote className="h-4 w-4 mr-2" />
               {t('notebookSuggestion.generalNotes')}
             </DropdownMenuItem>
-            {notebooks.map((notebook: any) => {
-              const NotebookIcon = getNotebookIcon(notebook.icon || 'folder')
-              return (
-                <DropdownMenuItem
-                  key={notebook.id}
-                  onClick={() => handleMoveToNotebook(notebook.id)}
-                >
-                  <NotebookIcon className="h-4 w-4 mr-2" />
-                  {notebook.name}
-                </DropdownMenuItem>
-              )
-            })}
+            {notebooks.filter(nb => !nb.parentId).map((notebook: any) => {
+               const NotebookIcon = getNotebookIcon(notebook.icon || 'folder')
+               const children = notebooks.filter((c: any) => c.parentId === notebook.id)
+               return (
+                 <div key={notebook.id}>
+                   <DropdownMenuItem onClick={() => handleMoveToNotebook(notebook.id)}>
+                     <NotebookIcon className="h-4 w-4 mr-2" />
+                     {notebook.name}
+                   </DropdownMenuItem>
+                   {children.map((child: any) => {
+                     const ChildIcon = getNotebookIcon(child.icon || 'folder')
+                     return (
+                       <DropdownMenuItem key={child.id} onClick={() => handleMoveToNotebook(child.id)} className="pl-8">
+                         <ChildIcon className="h-4 w-4 mr-2" />
+                         └ {child.name}
+                       </DropdownMenuItem>
+                     )
+                   })}
+                 </div>
+               )
+             })}
           </DropdownMenuContent>
         </DropdownMenu>
       </div>}
diff --git a/memento-note/components/notebook-tree-select.tsx b/memento-note/components/notebook-tree-select.tsx
new file mode 100644
index 0000000..9d2b77c
--- /dev/null
+++ b/memento-note/components/notebook-tree-select.tsx
@@ -0,0 +1,94 @@
+'use client'
+
+import { Notebook } from '@/lib/types'
+
+interface NotebookTreeSelectProps {
+  notebooks: Notebook[]
+  value: string | null
+  onChange: (notebookId: string | null) => void
+  placeholder?: string
+  inboxLabel?: string
+  className?: string
+}
+
+export function buildNotebookTree(notebooks: Notebook[]): { roots: Notebook[]; children: Map<string, Notebook[]> } {
+  const roots: Notebook[] = []
+  const children = new Map<string, Notebook[]>()
+  for (const nb of notebooks) {
+    if (nb.parentId) {
+      const arr = children.get(nb.parentId) || []
+      arr.push(nb)
+      children.set(nb.parentId, arr)
+    } else {
+      roots.push(nb)
+    }
+  }
+  return { roots, children }
+}
+
+export function NotebookTreeSelect({ notebooks, value, onChange, placeholder, inboxLabel, className }: NotebookTreeSelectProps) {
+  const { roots, children } = buildNotebookTree(notebooks)
+
+  return (
+    <select
+      value={value || ''}
+      onChange={e => onChange(e.target.value || null)}
+      className={className}
+    >
+      {placeholder && <option value="">{placeholder}</option>}
+      {inboxLabel && <option value="">{inboxLabel}</option>}
+      {roots.map(nb => (
+        <optgroup key={nb.id} label={nb.name}>
+          <option value={nb.id}>{nb.name}</option>
+          {(children.get(nb.id) || []).map(child => (
+            <option key={child.id} value={child.id}>  └ {child.name}</option>
+          ))}
+        </optgroup>
+      ))}
+    </select>
+  )
+}
+
+export function NotebookTreeList({ notebooks, activeNotebookId, onSelect, inboxLabel }: {
+  notebooks: Notebook[]
+  activeNotebookId: string | null
+  onSelect: (notebookId: string | null) => void
+  inboxLabel?: string
+}) {
+  const { roots, children } = buildNotebookTree(notebooks)
+
+  return (
+    <>
+      {inboxLabel && (
+        <button
+          type="button"
+          onClick={() => onSelect(null)}
+          className="flex w-full items-center gap-2 rounded px-2 py-1.5 text-[12px] font-medium hover:bg-muted transition-colors text-foreground/70"
+        >
+          {activeNotebookId === null ? '✓ ' : '  '}{inboxLabel}
+        </button>
+      )}
+      {roots.map(nb => (
+        <div key={nb.id}>
+          <button
+            type="button"
+            onClick={() => onSelect(nb.id)}
+            className="flex w-full items-center gap-2 rounded px-2 py-1.5 text-[12px] font-medium hover:bg-muted transition-colors text-foreground/70"
+          >
+            {activeNotebookId === nb.id ? '✓ ' : '  '}{nb.name}
+          </button>
+          {(children.get(nb.id) || []).map(child => (
+            <button
+              key={child.id}
+              type="button"
+              onClick={() => onSelect(child.id)}
+              className="flex w-full items-center gap-2 rounded pl-6 pr-2 py-1.5 text-[12px] font-medium hover:bg-muted transition-colors text-foreground/70"
+            >
+              {activeNotebookId === child.id ? '✓ ' : '  '}└ {child.name}
+            </button>
+          ))}
+        </div>
+      ))}
+    </>
+  )
+}
diff --git a/memento-note/components/notes-tabs-view.tsx b/memento-note/components/notes-tabs-view.tsx
index 215de8c..840de18 100644
--- a/memento-note/components/notes-tabs-view.tsx
+++ b/memento-note/components/notes-tabs-view.tsx
@@ -547,23 +547,36 @@ function NoteMetaSidebar({
                   : <span className="h-3 w-3 shrink-0" />}
                 {t('notes.generalNotes')}
               </button>
-              {notebooks.map((nb) => (
-                <button
-                  key={nb.id}
-                  type="button"
-                  onClick={() => handleMoveToNotebook(nb.id)}
-                  className={cn(
-                    'flex w-full items-center gap-2 rounded px-2 py-1.5 text-[12px] font-medium hover:bg-muted transition-colors',
-                    note.notebookId === nb.id ? 'text-primary' : 'text-foreground/70'
-                  )}
-                >
-                  {note.notebookId === nb.id
-                    ? <Check className="h-3 w-3 shrink-0" />
-                    : <span className="h-3 w-3 shrink-0" />}
-                  {nb.name}
-                </button>
-              ))}
-            </PopoverContent>
+              {notebooks.filter(nb => !nb.parentId).map((nb) => (
+                 <div key={nb.id}>
+                   <button
+                     type="button"
+                     onClick={() => handleMoveToNotebook(nb.id)}
+                     className={cn(
+                       'flex w-full items-center gap-2 rounded px-2 py-1.5 text-[12px] font-medium hover:bg-muted transition-colors',
+                       note.notebookId === nb.id ? 'text-primary' : 'text-foreground/70'
+                     )}
+                   >
+                     {note.notebookId === nb.id ? <Check className="h-3 w-3 shrink-0" /> : <span className="h-3 w-3 shrink-0" />}
+                     {nb.name}
+                   </button>
+                   {notebooks.filter(c => c.parentId === nb.id).map(child => (
+                     <button
+                       key={child.id}
+                       type="button"
+                       onClick={() => handleMoveToNotebook(child.id)}
+                       className={cn(
+                         'flex w-full items-center gap-2 rounded pl-6 pr-2 py-1.5 text-[12px] font-medium hover:bg-muted transition-colors',
+                         note.notebookId === child.id ? 'text-primary' : 'text-foreground/70'
+                       )}
+                     >
+                       {note.notebookId === child.id ? <Check className="h-3 w-3 shrink-0" /> : <span className="h-3 w-3 shrink-0" />}
+                       └ {child.name}
+                     </button>
+                   ))}
+                 </div>
+               ))}
+             </PopoverContent>
           </Popover>
 
           {/* Pin / Unpin */}