feat: compact mail folder tree + right-click Ordner leeren

- MailFolderTree: compact styling matching AI assistant SessionList (py-1, text-sm, depth*12+8 padding, no space-y)
- Added right-click context menu on folders with "Ordner leeren" entry
- Backend: POST /mail/folders/{folder_id}/empty soft-deletes all mails in folder
- Frontend API: emptyFolder() function added to mail.ts
- Mail.tsx: onFolderEmptied callback reloads mails and folders

app/plugins/builtins/mail/routes.py

@@ -587,6 +587,50 @@ async def delete_folder(
     await db.delete(folder)
 
 
+# ─── Empty Folder (soft-delete all mails in folder) ───
+
+
+@router.post("/folders/{folder_id}/empty")
+async def empty_folder(
+    folder_id: str,
+    db: AsyncSession = Depends(get_db),
+    current_user: dict = Depends(require_permission("mail:delete")),
+):
+    """Soft-delete all mails in a folder (sets deleted_at = now()).
+
+    The mails remain in the database but are hidden from the normal list.
+    Returns the number of mails that were emptied.
+    """
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    user_id = uuid.UUID(current_user["user_id"])
+    f_id = _parse_uuid(folder_id, "folder_id")
+    folder = (
+        await db.execute(
+            select(MailFolder).where(and_(MailFolder.id == f_id, MailFolder.tenant_id == tenant_id))
+        )
+    ).scalar_one_or_none()
+    if not folder:
+        raise HTTPException(404, detail={"detail": "Folder not found", "code": "not_found"})
+    account = await _get_account(db, folder.account_id, tenant_id, user_id)
+    await _check_delegate_access(db, account, user_id, "delete")
+    # Soft-delete all non-deleted mails in this folder
+    result = await db.execute(
+        select(Mail).where(
+            and_(
+                Mail.folder_id == f_id,
+                Mail.tenant_id == tenant_id,
+                Mail.deleted_at.is_(None),
+            )
+        )
+    )
+    mails = result.scalars().all()
+    now = datetime.now(UTC)
+    for mail in mails:
+        mail.deleted_at = now
+    await db.flush()
+    return {"emptied_count": len(mails)}
+
+
 # ─── Attachment Upload (F-MAIL-04) ───
 
 

frontend/src/api/mail.ts

@@ -475,6 +475,10 @@ export function deleteFolder(folderId: string): Promise<void> {
   return apiDelete<void>(`/mail/folders/${folderId}`);
 }
 
+export function emptyFolder(folderId: string): Promise<{ emptied_count: number }> {
+  return apiPost<{ emptied_count: number }>(`/mail/folders/${folderId}/empty`, {});
+}
+
 // ─── Mails ──────────────────────────────────────────────────────────────────
 
 export function fetchMails(folderId: string, page: number, sortBy?: string, sortOrder?: string): Promise<MailListResult> {

frontend/src/components/mail/MailFolderTree.tsx

@@ -2,12 +2,16 @@
  * Mail folder tree sidebar component.
  * Shows accounts as top-level nodes with their folders nested underneath.
  * Folders come as a flat list with parent_id and are built into a tree.
+ *
+ * Styling matches the AI assistant SessionList tree: compact font, tight spacing,
+ * right-click context menu with "Ordner leeren".
  */
 
-import React, { useState, useMemo } from 'react';
+import React, { useState, useMemo, useEffect, useRef, useCallback } from 'react';
 import clsx from 'clsx';
 import { useTranslation } from 'react-i18next';
 import type { MailAccount, MailFolder } from '@/api/mail';
+import { emptyFolder } from '@/api/mail';
 import { Badge } from '@/components/ui/Badge';
 import { EmptyState } from '@/components/ui/EmptyState';
 
@@ -54,6 +58,7 @@ export interface MailFolderTreeProps {
   selectedFolderId: string | null;
   onSelect: (folderId: string) => void;
   loading: boolean;
+  onFolderEmptied?: () => void;
 }
 
 /**
@@ -84,7 +89,7 @@ function buildFolderTree(folders: MailFolder[], accountId: string): MailFolder[]
 function ChevronIcon({ expanded }: { expanded: boolean }) {
   return (
     <svg
-      className={clsx('w-3 h-3 transition-transform flex-shrink-0', expanded ? 'rotate-90' : '')}
+      className={clsx('w-4 h-4 transition-transform flex-shrink-0', expanded && 'rotate-90')}
       fill="none"
       viewBox="0 0 24 24"
       stroke="currentColor"
@@ -97,17 +102,51 @@ function ChevronIcon({ expanded }: { expanded: boolean }) {
 
 function FolderIcon() {
   return (
-    <svg className="w-4 h-4 flex-shrink-0" fill="none" viewBox="0 0 24 24" stroke="currentColor" aria-hidden="true">
+    <svg className="w-4 h-4 text-secondary-400 flex-shrink-0" fill="none" viewBox="0 0 24 24" stroke="currentColor" aria-hidden="true">
       <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M3 7v10a2 2 0 002 2h14a2 2 0 002-2V9a2 2 0 00-2-2h-6l-2-2H5a2 2 0 00-2 2z" />
     </svg>
   );
 }
 
-function MailIcon() {
+interface ContextMenuState {
+  x: number;
+  y: number;
+  folderId: string;
+  folderName: string;
+}
+
+function ContextMenu({
+  state,
+  onClose,
+  onEmptyFolder,
+}: {
+  state: ContextMenuState;
+  onClose: () => void;
+  onEmptyFolder: (folderId: string, folderName: string) => void;
+}) {
+  const ref = useRef<HTMLDivElement>(null);
+
+  useEffect(() => {
+    const handler = (e: MouseEvent) => {
+      if (ref.current && !ref.current.contains(e.target as Node)) onClose();
+    };
+    document.addEventListener('mousedown', handler);
+    return () => document.removeEventListener('mousedown', handler);
+  }, [onClose]);
+
   return (
-    <svg className="w-4 h-4 flex-shrink-0" fill="none" viewBox="0 0 24 24" stroke="currentColor" aria-hidden="true">
+    <div
-      <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M3 8l7-7 7 7M5 19h10a2 2 0 002-2V8l-5-5H5a2 2 0 00-2 2v12a2 2 0 002 2z" />
+      ref={ref}
-    </svg>
+      className="fixed z-50 bg-white border border-secondary-200 rounded-lg shadow-lg py-1 min-w-[160px]"
+      style={{ left: state.x, top: state.y }}
+    >
+      <button
+        onClick={() => { onEmptyFolder(state.folderId, state.folderName); onClose(); }}
+        className="w-full text-left px-3 py-1.5 text-sm text-red-600 hover:bg-red-50"
+      >
+        Ordner leeren
+      </button>
+    </div>
   );
 }
 
@@ -116,11 +155,13 @@ function FolderNode({
   selectedFolderId,
   onSelect,
   depth,
+  onContextMenu,
 }: {
   folder: MailFolder;
   selectedFolderId: string | null;
   onSelect: (folderId: string) => void;
   depth: number;
+  onContextMenu: (e: React.MouseEvent, folder: MailFolder) => void;
 }) {
   const [expanded, setExpanded] = useState(true);
   const isSelected = folder.id === selectedFolderId;
@@ -128,7 +169,10 @@ function FolderNode({
 
   return (
     <div role="treeitem" aria-selected={isSelected} aria-label={getFolderDisplayName(folder)}>
-      <div className="flex items-center" style={{ paddingLeft: `${depth * 12}px` }}>
+      <div
+        className="flex items-center"
+        style={{ paddingLeft: `${depth * 12 + 8}px` }}
+      >
         {hasChildren ? (
           <button
             onClick={(e) => {
@@ -146,12 +190,13 @@ function FolderNode({
         )}
         <button
           onClick={() => onSelect(folder.id)}
+          onContextMenu={(e) => onContextMenu(e, folder)}
           className={clsx(
-            'flex-1 flex items-center gap-1.5 px-2 py-1 md:py-1 rounded-md text-sm min-h-touch',
+            'group flex-1 flex items-center gap-1 px-2 py-1 rounded-md text-sm cursor-pointer',
             'motion-safe:transition-colors focus:outline-none focus-visible:ring-2 focus-visible:ring-primary-500',
             isSelected
               ? 'bg-primary-50 text-primary-700 font-medium'
-              : 'hover:bg-secondary-50 text-secondary-700',
+              : 'hover:bg-secondary-100 text-secondary-700',
           )}
           data-testid={`folder-${folder.id}`}
         >
@@ -174,6 +219,7 @@ function FolderNode({
               selectedFolderId={selectedFolderId}
               onSelect={onSelect}
               depth={depth + 1}
+              onContextMenu={onContextMenu}
             />
           ))}
         </div>
@@ -187,11 +233,13 @@ function AccountNode({
   folders,
   selectedFolderId,
   onSelect,
+  onContextMenu,
 }: {
   account: MailAccount;
   folders: MailFolder[];
   selectedFolderId: string | null;
   onSelect: (folderId: string) => void;
+  onContextMenu: (e: React.MouseEvent, folder: MailFolder) => void;
 }) {
   const [expanded, setExpanded] = useState(true);
   const accountFolders = useMemo(
@@ -203,14 +251,14 @@ function AccountNode({
     <div role="treeitem" aria-label={account.email}>
       <button
         onClick={() => setExpanded(!expanded)}
-        className="w-full flex items-center gap-1 px-1 py-2 md:py-1.5 rounded-md text-sm font-semibold text-secondary-900 hover:bg-secondary-50 min-h-touch"
+        className="w-full flex items-center gap-1 px-2 py-1.5 rounded-md text-sm font-medium text-secondary-700 hover:bg-secondary-100"
         data-testid={`account-${account.id}`}
       >
         <ChevronIcon expanded={expanded} />
         <span className="flex-1 truncate text-left">{account.display_name || account.email}</span>
       </button>
       {expanded && (
-        <div role="group" className="ml-2">
+        <div role="group">
           {accountFolders.map((folder) => (
             <FolderNode
               key={folder.id}
@@ -218,6 +266,7 @@ function AccountNode({
               selectedFolderId={selectedFolderId}
               onSelect={onSelect}
               depth={0}
+              onContextMenu={onContextMenu}
             />
           ))}
         </div>
@@ -226,8 +275,31 @@ function AccountNode({
   );
 }
 
-export function MailFolderTree({ accounts, folders, selectedFolderId, onSelect, loading }: MailFolderTreeProps) {
+export function MailFolderTree({ accounts, folders, selectedFolderId, onSelect, loading, onFolderEmptied }: MailFolderTreeProps) {
   const { t } = useTranslation();
+  const [contextMenu, setContextMenu] = useState<ContextMenuState | null>(null);
+
+  const handleContextMenu = useCallback((e: React.MouseEvent, folder: MailFolder) => {
+    e.preventDefault();
+    e.stopPropagation();
+    setContextMenu({
+      x: e.clientX,
+      y: e.clientY,
+      folderId: folder.id,
+      folderName: getFolderDisplayName(folder),
+    });
+  }, []);
+
+  const handleEmptyFolder = useCallback(async (folderId: string, folderName: string) => {
+    if (!confirm(`Ordner "${folderName}" wirklich leeren? Alle E-Mails werden gelöscht.`)) return;
+    try {
+      const result = await emptyFolder(folderId);
+      if (onFolderEmptied) onFolderEmptied();
+    } catch (e) {
+      console.error('Failed to empty folder:', e);
+      alert('Fehler beim Leeren des Ordners: ' + (e instanceof Error ? e.message : String(e)));
+    }
+  }, [onFolderEmptied]);
 
   if (loading) {
     return (
@@ -252,7 +324,8 @@ export function MailFolderTree({ accounts, folders, selectedFolderId, onSelect,
   }
 
   return (
-    <div className="space-y-1" role="tree" data-testid="folder-tree-list">
+    <>
+      <div className="flex flex-col" role="tree" data-testid="folder-tree-list">
         {accounts.map((account) => (
           <AccountNode
             key={account.id}
@@ -260,8 +333,17 @@ export function MailFolderTree({ accounts, folders, selectedFolderId, onSelect,
             folders={folders}
             selectedFolderId={selectedFolderId}
             onSelect={onSelect}
+            onContextMenu={handleContextMenu}
           />
         ))}
       </div>
+      {contextMenu && (
+        <ContextMenu
+          state={contextMenu}
+          onClose={() => setContextMenu(null)}
+          onEmptyFolder={handleEmptyFolder}
+        />
+      )}
+    </>
   );
 }

frontend/src/pages/Mail.tsx

@@ -736,6 +736,7 @@ export function MailPage() {
               selectedFolderId={selectedFolderId}
               onSelect={handleSelectFolder}
               loading={loadingFolders}
+              onFolderEmptied={() => { loadMails(); loadAllFolders(); }}
             />
           </div>
         </ResizablePanel>