fix(cloud-files): Pin loest Hydration aus, Icon-Refresh via SHChangeNotify

CfSetPinState aendert nur das Pin-Flag - ohne expliziten Call
passiert am Disk-Inhalt nichts und das Explorer-Icon bleibt
unveraendert. Darum klickte "Immer offline verfuegbar" scheinbar
ins Leere.

- Bei Pin: CfHydratePlaceholder triggert FETCH_DATA und laedt die
  Datei komplett herunter
- Bei Unpin: CfDehydratePlaceholder (war schon da)
- Nach jeder Zustandsaenderung SHChangeNotify(SHCNE_UPDATEITEM)
  damit das Overlay-Icon sofort neu gezeichnet wird, ohne dass
  der User F5 druecken muss
- Log bekommt zusaetzlich hydrate_err fuer Debugging

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.env.example

@@ -31,7 +31,36 @@ FRONTEND_URL=https://cloud.example.com
 # Max Upload-Groesse in MB
 MAX_UPLOAD_SIZE_MB=500
 
+# Zeitzone (prozessweit) - IANA-Format "Region/Stadt".
+# Wirkt auf datetime.now(), strftime %Z und Kalender/Task-Zeitstempel.
+# Haeufige Werte:
+#   Europe/Berlin, Europe/Vienna, Europe/Zurich, Europe/Amsterdam,
+#   Europe/Paris, Europe/London, Europe/Madrid, Europe/Rome,
+#   Europe/Warsaw, Europe/Prague, Europe/Copenhagen, Europe/Stockholm,
+#   UTC, America/New_York, America/Los_Angeles, Asia/Tokyo, Australia/Sydney
+# Vollstaendige Liste: https://en.wikipedia.org/wiki/List_of_tz_database_time_zones
+TZ=Europe/Berlin
+
+# NTP-Server zum Pruefen der Uhrzeit beim Start (nicht-invasiver Offset-Check
+# - im Container kann die Systemuhr nicht gesetzt werden; bei Abweichung >5s
+# erscheint eine Warnung im Log, dann bitte die Host-Uhr synchronisieren).
+# Leerlassen um den Check zu deaktivieren.
+# Default: Physikalisch-Technische Bundesanstalt (offizielle deutsche Zeit).
+# Alternativen: ptbtime2.ptb.de, ptbtime3.ptb.de, de.pool.ntp.org, time.cloudflare.com
+NTP_SERVER=ptbtime1.ptb.de
+
 # OnlyOffice Document Server (optional)
 # Eigene Subdomain mit HTTPS, z.B. https://office.example.com
 # JWT wird automatisch vom JWT_SECRET_KEY oben verwendet
 ONLYOFFICE_URL=
+
+# =============================================
+# Client-Build Upload (NUR auf der ENTWICKLUNGSMASCHINE!)
+# NICHT auf dem Produktionsserver setzen!
+# Diese Werte braucht nur die Maschine auf der ./build.sh laeuft.
+# =============================================
+# URL der Cloud-Instanz wohin die Builds hochgeladen werden
+CLOUD_URL=https://cloud.example.com
+# SECRET_KEY oder JWT_SECRET_KEY des Zielservers
+# (den gleichen Wert hier reinkopieren der auf dem Server steht)
+BUILD_UPLOAD_TOKEN=

.gitignore

@@ -39,5 +39,8 @@ backend/static/
 .DS_Store
 Thumbs.db
 
+# Build output
+build-output/
+
 # Logs
 *.log

CHANGELOG.md

@@ -0,0 +1,227 @@
+# Changelog
+
+Alle wesentlichen Aenderungen an der Mini-Cloud Plattform.
+
+---
+
+## [0.9.0] - 2026-04-12 - Desktop Sync Client
+
+### Desktop-Client (Tauri 2 / Rust + Vue)
+- **Erster funktionsfaehiger Desktop Sync Client** fuer Windows, Linux und macOS
+- Multi-Sync-Pfade: Beliebig viele Server-Ordner auf lokale Ordner mappen
+- Virtual Files: `.cloud`-Platzhalter (0 Bytes), Download erst bei Doppelklick
+- Full Sync: Alternativ alle Dateien komplett lokal spiegeln (pro Pfad waehlbar)
+- Offline-Markierung: Einzelne Dateien als offline verfuegbar markieren (Rechtsklick)
+- Sofort-Sync: Filesystem-Watcher erkennt Aenderungen sofort (3s Debounce statt Polling)
+- Bidirektionaler Sync mit Timestamp-Vergleich (Server neuer = Download, Lokal neuer = Upload)
+- File Locking: Automatisches Ein-/Auschecken mit Heartbeat alle 10s
+- Auto-Unlock: Erkennt wenn eine Datei geschlossen wird (Windows: Write-Lock-Check, Linux: lsof)
+- System-Tray: Minimiert in den Tray statt zu beenden, Doppelklick oeffnet Fenster
+- Auto-Login: Zugangsdaten und Sync-Pfade persistent in `%APPDATA%/MiniCloud Sync/config.json`
+- Single-Instance pro User (Terminalserver-kompatibel, PID-basiertes Lock-File)
+- .cloud Datei-Assoziation: Doppelklick im Explorer oeffnet ueber den Client
+- Minimiert starten: Checkbox in Einstellungen, Client startet direkt im Tray
+- Token-Refresh alle 10 Minuten (verhindert Lock-Verlust nach Token-Ablauf)
+- Lokaler Datei-Browser mit Rechtsklick-Kontextmenue
+
+### Build-System
+- `build.sh` Script: Baut Clients via Docker fuer alle Plattformen
+- `./build.sh windows` - Cross-Compile von Linux nach Windows (NSIS-Installer mit WebView2)
+- `./build.sh linux` - Linux Build (.AppImage, .deb)
+- `./build.sh mac` - macOS Build (.dmg, nur auf Mac)
+- Auto-Upload: Gebaute Clients werden automatisch auf den Cloud-Server hochgeladen
+- Client-Downloads: Login-Seite und Benutzer-Einstellungen zeigen Download-Links
+
+### File Locking (Backend)
+- Neues FileLock-Model: Dateien ein-/auschecken
+- API: Lock, Unlock, Heartbeat, Lock-Status
+- Auto-Unlock nach 15 Minuten ohne Heartbeat
+- Lock-Anzeige in der Dateiliste (Schloss-Icon mit Benutzername)
+- Gesperrte Dateien: Oeffnen nicht moeglich, Fehlermeldung
+- Konflikt-Email an Admin bei erzwungenem Sync gesperrter Dateien
+
+---
+
+## [0.8.0] - 2026-04-11 - OnlyOffice + Papierkorb
+
+### OnlyOffice Document Server Integration
+- Word, Excel und PowerPoint Dateien direkt im Browser bearbeiten
+- Automatische Erkennung: OnlyOffice vorhanden = Editor, sonst einfache Vorschau
+- WOPI-aehnliche Endpunkte fuer Dokumentzugriff und Callback
+- JWT-Signierung (nutzt JWT_SECRET_KEY aus .env, kein extra Secret)
+- Force-Save: Ctrl+S speichert sofort zurueck zum Server
+- Dokument-Key mit Timestamp (kein Cache-Problem bei Wiederoffnen)
+- Konfiguration nur ueber .env (ONLYOFFICE_URL), Admin-GUI zeigt Status
+
+### Papierkorb
+- Geloeschte Dateien landen im Papierkorb statt sofort geloescht zu werden
+- Papierkorb-Seite in der Sidebar mit Tabelle aller geloeschten Elemente
+- Wiederherstellen am Originalort oder endgueltig loeschen
+- "Papierkorb leeren" Button mit Sicherheitsabfrage
+- Share-View Loeschen nutzt ebenfalls den Papierkorb
+
+### Bestaetigungsdialoge
+- Ueberall wo geloescht wird jetzt ein Bestaetigungsdialog
+- Kontakte, Kalender-Events, Kalender, E-Mails, Share-Dateien,
+  SFTP-Backup-Ziele, Admin Email-Konten
+
+### Office-Preview
+- Vorschau oeffnet sich innerhalb der App (kein neuer Tab)
+- Zurueck-Button in der Toolbar
+- PDF inline, Bilder zentriert, DOCX als HTML, XLSX als Tabelle, PPTX als Folien
+- Text/Code-Dateien bearbeitbar mit Speichern-Funktion
+
+---
+
+## [0.7.0] - 2026-04-11 - Backup & Restore + SFTP
+
+### Backup & Restore
+- Lokales ZIP-Backup: Datenbank (sqlite3.backup API) + alle Dateien + Metadaten
+- Streaming-Download ohne Speicher-Limits
+- Chunked Restore-Upload fuer grosse Backups (10MB-Stuecke mit Fortschrittsbalken)
+- DB-Merge-Strategie: INSERT OR REPLACE auf gemeinsame Spalten
+- Einzeldatei-Restore: Backup durchsuchen + einzelne Dateien herunterladen/wiederherstellen
+
+### SFTP-Backup
+- Mehrere SFTP-Backup-Ziele konfigurierbar
+- Automatischer Hintergrund-Scheduler (15 Min. bis woechentlich)
+- Versionierung mit automatischem Aufraumen alter Backups
+- Manuelles Backup per Klick ("Jetzt sichern")
+- SFTP-Verbindungstest-Button
+- Versionen-Dialog: Alle Backups auf dem SFTP-Server auflisten
+- Restore direkt von SFTP: Version auswaehlen und wiederherstellen
+
+### Restore-Anleitung
+- Detaillierte Anleitung direkt in der Admin-UI
+- Hinweis auf SECRET_KEY/JWT_SECRET_KEY Uebereinstimmung
+
+---
+
+## [0.6.0] - 2026-04-11 - Drag & Drop + Share-Typen
+
+### Datei-Upload
+- Drag & Drop Upload: Dateien und komplette Ordnerstrukturen reinziehen
+- Ordner-Button: Kompletten Ordner mit Unterordnern hochladen (webkitdirectory)
+- Upload-Fortschrittsbalken mit Datei-Zaehler
+- Backend: `/files/ensure-path` erstellt verschachtelte Ordnerstrukturen
+
+### Share-Links
+- Drei Berechtigungsstufen: Nur Lesen / Lesen+Schreiben / Nur Upload
+- Upload-Only: Briefkasten-Modus (hochladen ohne Einblick)
+- Ordner-Freigaben: Dateiliste mit Download/Loeschen, Unterordner-Navigation
+- Ordner als ZIP herunterladen (rekursiv)
+- Share-Status visuell: Gruenes Icon zeigt geteilte Dateien an
+- Upload in freigegebene Ordner mit Passwort-Schutz
+
+### System-Benachrichtigungen
+- Email bei Datei-/Ordner-Freigabe an Empfaenger
+- Email bei Share-Link-Download an Ersteller (mit IP-Adresse)
+- Email bei Upload in geteilten Ordner
+- Email bei Kalender/Kontakte/Passwort-Freigabe
+- Email bei Benutzer-Erstellung durch Admin
+- Alle Benachrichtigungen fail-safe (keine Blockierung bei Email-Fehler)
+
+---
+
+## [0.5.0] - 2026-04-11 - Admin-Features + Passwort-Import
+
+### Administration
+- Benutzer ueber Web-UI anlegen (Username, Email, Passwort, Rolle, Quota)
+- Benutzer bearbeiten/deaktivieren/loeschen mit Sicherheitsabfragen
+- Email-Konten pro Benutzer im Admin verwalten (ohne sich als User einzuloggen)
+- Benutzersuche in der Verwaltung
+- Oeffentliche Registrierung: Schieberegler an/aus
+- Einladungslinks: Einmal-Token auch bei deaktivierter Registrierung
+- System-Email (SMTP): Konfigurierbar mit Verbindungstest
+
+### Passwort-Manager Import
+- Firefox CSV-Import (Einstellungen > Passwoerter > Exportieren)
+- KeePass .kdbx Import mit Ordnerstruktur
+- Generischer CSV-Import (Chrome, Bitwarden, 1Password)
+- Automatische Spaltenerkennung (deutsch + englisch)
+- Alle Eintraege werden clientseitig verschluesselt vor dem Speichern
+
+---
+
+## [0.4.0] - 2026-04-11 - Dateiverwaltung + Share-Links
+
+### Dateiverwaltung
+- Upload/Download mit Berechtigungen (read/write/admin)
+- Ordner erstellen, verschieben, umbenennen, loeschen
+- Berechtigungssystem pro Datei/Ordner und Benutzer
+
+### Share-Links
+- Token-basierte Freigabe-Links
+- Optionales Passwort + Ablaufdatum + Download-Limit
+- Oeffentliche Share-Seite ohne Login
+- Dateien/Ordner mit Benutzern teilen (Benutzersuche)
+
+### Sync-API
+- `GET /sync/tree` - Kompletter Dateibaum mit Checksums
+- `GET /sync/changes?since=` - Delta-Sync
+- SHA-256 Checksums fuer Duplikat-Erkennung
+
+---
+
+## [0.3.0] - 2026-04-11 - Kalender + Kontakte + Email
+
+### Kalender
+- Kalender-CRUD mit Events (Monats-/Tagesansicht, FullCalendar)
+- Kalender mit Benutzern teilen (Lesen oder Lesen+Schreiben)
+- iCal-Export als Read-Only .ics Link
+- CalDAV well-known URLs fuer Auto-Discovery (iOS, DAVx5, Thunderbird)
+
+### Kontakte
+- Adressbuecher + Kontakte CRUD
+- vCard-Export, Teilen mit Benutzern
+- Suche in Kontakten
+
+### Email-Webclient
+- IMAP/SMTP-Proxy (kein eigener Mailserver)
+- Multi-Account: Ordner nach Konten gruppiert
+- Absender-Logik: Standard = aktives Konto, Dropdown bei mehreren
+- Drei-Spalten-Layout, Compose mit Reply
+- Kein Email-Konto = Email-Bereich ausgeblendet
+
+---
+
+## [0.2.0] - 2026-04-11 - Passwort-Manager + Office-Viewer
+
+### Passwort-Manager
+- AES-256-GCM clientseitig verschluesselt (Zero Knowledge)
+- TOTP-Code Generierung (Web Crypto API)
+- Passwort-Generator
+- Ordner/Gruppen-Hierarchie (wie KeePass)
+- Teilen von Eintraegen und Ordnern (read/write/manage)
+
+### Office-Viewer
+- PDF: PDF.js direkt im Browser
+- DOCX: python-docx -> HTML
+- XLSX: openpyxl -> JSON -> Tabelle
+- PPTX: python-pptx -> HTML-Folien
+- Bilder und Textdateien inline
+
+---
+
+## [0.1.0] - 2026-04-11 - Erste Version
+
+### Grundgeruest
+- Flask Backend mit SQLAlchemy + SQLite (WAL-Modus)
+- Vue 3 Frontend mit PrimeVue, Vite, Pinia
+- JWT-Authentifizierung (Access + Refresh Token)
+- Erster Benutzer wird automatisch Admin
+- Benutzerverwaltung (Admin/User Rollen, Speicher-Quotas)
+
+### Projekt-Setup
+- `.gitignore`, `.env.example` mit Token-Generierung
+- Dockerfile (Multi-Stage: Node Build + Python Production)
+- `docker-compose.yml` mit Bind Mounts (keine Docker Volumes)
+- `nginx.example.conf` fuer Reverse-Proxy mit Let's Encrypt
+
+### Datenbank
+- 15 Tabellen: Users, Files, FilePermissions, ShareLinks, Calendars,
+  CalendarEvents, CalendarShares, AddressBooks, Contacts,
+  AddressBookShares, EmailAccounts, PasswordFolders, PasswordEntries,
+  PasswordShares, AppSettings
+- Auto-Migrate: Fehlende Spalten werden beim App-Start automatisch
+  per ALTER TABLE hinzugefuegt (kein manuelles Migrieren noetig)

Dockerfile

@@ -11,6 +11,7 @@ FROM python:3.11-slim
 WORKDIR /app
 
 # Install system dependencies
+# tzdata ist im python:3.11-slim bereits enthalten - nur gcc nachinstallieren.
 RUN apt-get update && apt-get install -y --no-install-recommends \
     gcc \
     && rm -rf /var/lib/apt/lists/*
@@ -30,9 +31,17 @@ RUN mkdir -p /app/data/files
 
 # Environment
 ENV FLASK_ENV=production
+ENV TZ=Europe/Berlin
 ENV DATABASE_PATH=/app/data/minicloud.db
 ENV UPLOAD_PATH=/app/data/files
 
 EXPOSE 5000
 
-CMD ["gunicorn", "--bind", "0.0.0.0:5000", "--workers", "4", "--timeout", "120", "wsgi:application"]
+# Single worker with many threads. The SSE broadcaster lives in process
+# memory - mit mehreren Workern wuerden Events den Empfaenger nicht
+# erreichen wenn Sender und Empfaenger auf verschiedenen Workern haengen.
+# 32 Threads = bis zu 32 gleichzeitige Requests/SSE-Streams.
+CMD ["gunicorn", "--bind", "0.0.0.0:5000", \
+     "--worker-class", "gthread", "--workers", "1", "--threads", "32", \
+     "--timeout", "120", "--keep-alive", "65", \
+     "wsgi:application"]

README.md

@@ -93,6 +93,31 @@ docker-compose up --build -d
 
 Die Datenbank und hochgeladene Dateien liegen unter `./data/` (Bind Mount, keine Docker Volumes).
 
+### Docker aufraeumen (Speicher freigeben)
+
+Nach vielen Builds sammeln sich alte Images und Cache-Layer an:
+
+```bash
+# Alles Ungenutzte loeschen (Images, Container, Cache, Netzwerke):
+docker system prune -a -f
+
+# Nur alte/ungenutzte Images loeschen:
+docker image prune -a -f
+
+# Nur Build-Cache loeschen:
+docker builder prune -a -f
+
+# Speicherverbrauch anzeigen:
+docker system df
+```
+
+Bei Problemen nach Updates (alte Frontend-Version etc.):
+```bash
+docker-compose down
+docker-compose build --no-cache
+docker-compose up -d
+```
+
 ### Nginx Reverse-Proxy (Beispiel)
 
 Die Datei `nginx.example.conf` enthaelt eine vollstaendige Beispielkonfiguration:
@@ -166,6 +191,36 @@ docker-compose up --build -d
 
 **Ohne OnlyOffice** (`ONLYOFFICE_URL` leer) werden Office-Dateien in einer einfachen Vorschau angezeigt. **Mit OnlyOffice** erhaelt man einen vollwertigen Editor (wie Google Docs).
 
+### Zeitzone & NTP
+
+In der `.env` stehen zwei Variablen die die Systemzeit betreffen:
+
+```env
+TZ=Europe/Berlin
+NTP_SERVER=ptbtime1.ptb.de
+```
+
+**`TZ`** setzt die prozessweite Zeitzone (wirkt auf Log-Zeitstempel, Kalender/Task-Zeiten, `datetime.now()`). IANA-Format `Region/Stadt`.
+
+Haeufige Werte:
+
+| Region      | Beispielwerte                                                                                                                          |
+| ----------- | -------------------------------------------------------------------------------------------------------------------------------------- |
+| Deutschland | `Europe/Berlin`                                                                                                                        |
+| DACH/EU     | `Europe/Vienna`, `Europe/Zurich`, `Europe/Amsterdam`, `Europe/Paris`, `Europe/London`, `Europe/Madrid`, `Europe/Rome`, `Europe/Warsaw` |
+| Nord-EU     | `Europe/Copenhagen`, `Europe/Stockholm`, `Europe/Helsinki`, `Europe/Oslo`                                                              |
+| Sonstige    | `UTC`, `America/New_York`, `America/Los_Angeles`, `Asia/Tokyo`, `Australia/Sydney`                                                     |
+
+Vollstaendige Liste: <https://en.wikipedia.org/wiki/List_of_tz_database_time_zones>
+
+**`NTP_SERVER`** wird beim Start abgefragt, um die Abweichung der Systemuhr zu pruefen. Bei Drift > 5 s erscheint eine Warnung im Log. **Hinweis:** Im Container wird die Uhr dadurch nicht gesetzt (benoetigt `CAP_SYS_TIME`) - auf dem Host sollte ein NTP-Daemon laufen. Der Check dient nur zur Sichtbarkeit.
+
+Default: `ptbtime1.ptb.de` (offizielle deutsche Zeitreferenz der Physikalisch-Technischen Bundesanstalt, Stratum 1, sehr hohe Verfuegbarkeit).
+
+Alternativen: `ptbtime2.ptb.de`, `ptbtime3.ptb.de`, `de.pool.ntp.org`, `time.cloudflare.com`. Leerlassen um den Check zu deaktivieren.
+
+Aktuelle Werte sind im Admin-Bereich unter **Einstellungen > System** einsehbar.
+
 ## Verwendung
 
 ### Dateien
@@ -185,14 +240,32 @@ docker-compose up --build -d
 
 ### Kalender
 
-- Kalender erstellen, Events anlegen (Monats-/Tagesansicht)
+- Monats-/Wochen-/Tagesansicht (FullCalendar)
+- Drag & Drop zwischen Tagen, Termindauer per Rand-Ziehen
+- Wiederkehrende Termine: taeglich/woechentlich/monatlich/jaehrlich,
+  "jeden 2. Mittwoch", eigene Intervalle, Enddatum oder Anzahl
+- Serientermine: "Nur diesen" oder "Ganze Serie" bearbeiten
+- Kalender-Sichtbarkeit pro Kalender per Checkbox
 - Kalender mit anderen Benutzern teilen (Lesen oder Lesen+Schreiben)
-- iCal-Link generieren fuer Read-Only-Import in Google Calendar, Apple Kalender etc.
+- iCal-Abo-Link mit optionalem Passwort (HTTP Basic Auth)
-- CalDAV-Zugriff fuer native Sync:
+- Voller CalDAV-Server (RFC 4791 Subset) - siehe unten
-  - **iOS**: Einstellungen > Kalender > Accounts > Anderer > CalDAV
+
-  - **Android (DAVx5)**: Server-URL: `https://<deine-domain>/dav/`
+#### CalDAV-Zugriff
-  - **Thunderbird**: Neuer Kalender > Im Netzwerk > CalDAV
+
-  - **Outlook (CalDAV-Synchronizer)**: Server-URL: `https://<deine-domain>/dav/`
+Native Sync mit Handy/Laptop-Kalendern. Server-URL ist immer
+`https://<deine-domain>/dav/` - Benutzername + Passwort wie im Web.
+
+| Client          | Einrichtung |
+|-----------------|-------------|
+| **iOS/macOS**   | Einstellungen > Kalender > Accounts > Anderer > CalDAV-Account, Server `cloud.example.com/dav/` |
+| **Android (DAVx5)** | Konto hinzufuegen > Anmeldung mit URL und Benutzername, URL `https://cloud.example.com/dav/` |
+| **Thunderbird** | Neuer Kalender > Im Netzwerk > CalDAV, URL `https://cloud.example.com/dav/` (Thunderbird findet die Kalender selbst) |
+| **Outlook**     | Plugin CalDAV-Synchronizer, Server-URL `https://cloud.example.com/dav/` |
+
+Unterstuetzte Operationen: PROPFIND (Auto-Discovery via `/.well-known/caldav`),
+REPORT (calendar-query / calendar-multiget inkl. Zeitraumfilter), GET/PUT/DELETE
+fuer einzelne Termine, MKCALENDAR, EXDATE fuer Serienausnahmen. ETags werden
+benutzt damit Clients erkennen, was sich geaendert hat.
 
 ### Kontakte
 
@@ -268,10 +341,144 @@ data/             # Laufzeitdaten (gitignored)
   files/          # Hochgeladene Dateien
 ```
 
+## Desktop Sync Client
+
+Der Desktop-Client (`clients/desktop/`) synchronisiert Dateien zwischen der Cloud und einem lokalen Ordner. Gebaut mit Tauri 2 (Rust + Vue).
+
+### Features
+
+- **Multi-Sync-Pfade**: Beliebig viele Server-Ordner auf lokale Ordner mappen (z.B. `/Projekte` -> `~/Projekte`, `/Shared/Team` -> `~/Team`)
+- **Virtual Files**: `.cloud`-Platzhalter (0 Bytes), Download erst bei Doppelklick. Kein Speicherverbrauch fuer nicht benoetigte Dateien
+- **Full Sync**: Alternativ alle Dateien komplett lokal spiegeln (pro Pfad waehlbar)
+- **Offline-Markierung**: Einzelne Dateien als offline verfuegbar markieren (Rechtsklick im Datei-Browser)
+- **Sofort-Sync**: Filesystem-Watcher erkennt lokale Aenderungen sofort (3s Debounce), kein Polling
+- **Intelligenter Sync**: Checksum-Tracking erkennt wer sich geaendert hat (Server oder Lokal)
+- **Konflikt-Erkennung**: Bei gleichzeitiger Aenderung wird eine Konflikt-Kopie erstellt
+- **File Locking**: Lock beim Oeffnen, Heartbeat alle 60s, manuelles Entsperren per Rechtsklick, auto-unlock nach 15 Min ohne Heartbeat
+- **System-Tray**: Minimiert in den Tray statt zu beenden, Doppelklick oeffnet Fenster
+- **Minimiert starten**: Optional direkt im Tray starten (Checkbox in Einstellungen)
+- **Auto-Login**: Zugangsdaten und Sync-Pfade bleiben nach Neustart/Update erhalten
+- **Terminalserver**: Pro User eine eigene Instanz, keine Konflikte zwischen Benutzern
+- **.cloud Datei-Handler**: Doppelklick im Explorer oeffnet ueber den Client
+
+### Terminalserver-Verhalten
+
+| Szenario | Verhalten |
+|----------|-----------|
+| User A startet Client | Laeuft, eigenes Lock-File in `%APPDATA%\MiniCloud Sync\` |
+| User B startet Client | Laeuft separat, eigenes Lock-File in seinem `%APPDATA%` |
+| User A doppelklickt `.cloud` | Laufende Instanz von User A oeffnet die Datei |
+| User A startet nochmal | "Already running" -> beendet sich sofort |
+| Client crashed | Naechster Start prueft ob PID noch lebt -> stale Lock -> ueberschreibt |
+
+### Virtual Files vs. Full Sync
+
+| | Virtual Files | Full Sync |
+|---|---|---|
+| Speicher | Nur .cloud Platzhalter (0 Bytes) | Alle Dateien komplett lokal |
+| Zugriff | Doppelklick = Download + Oeffnen | Sofort verfuegbar |
+| Offline | Nur markierte Dateien | Alles offline |
+| Upload | Neue lokale Dateien werden hochgeladen | Bidirektionaler Sync |
+| Empfehlung | Grosse Datenmengen, Laptops | Kleine Ordner, immer offline noetig |
+
+### Sync-Logik (Checksum-Tracking)
+
+Der Client merkt sich den Checksum jeder Datei beim letzten Sync. Beim naechsten Sync wird verglichen wer sich geaendert hat:
+
+| Lokal geaendert | Server geaendert | Aktion |
+|-----------------|------------------|--------|
+| Nein | Ja | **Server -> Lokal** (Download) |
+| Ja | Nein | **Lokal -> Server** (Upload) |
+| Ja | Ja | **Konflikt**: Lokale Datei wird zu `Datei (Konflikt).txt`, Server-Version wird heruntergeladen |
+| Nein | Nein | Nichts (identisch) |
+
+Beim ersten Sync (kein gespeicherter Checksum) gewinnt immer der Server.
+
+### File Locking
+
+Dateien werden beim Oeffnen ueber den Client automatisch auf dem Server gesperrt. Andere Benutzer sehen "Datei gesperrt von X" und koennen sie nicht bearbeiten.
+
+| Szenario | Was passiert |
+|----------|-------------|
+| .cloud Datei oeffnen | Download + Lock + Heartbeat alle 60s |
+| Fertig -> Rechtsklick "Entsperren" | Lock sofort aufgehoben |
+| Rechtsklick "Nicht mehr offline" | Lock aufgehoben + zurueck zu .cloud |
+| Client beenden ohne Entsperren | Kein Heartbeat -> Lock laeuft nach 15 Min ab |
+| Laptop zugeklappt / Netzwerk weg | Kein Heartbeat -> Lock laeuft nach 15 Min ab |
+| Admin im Web-UI | Kann jeden Lock jederzeit manuell loesen |
+
+#### Was das Lock wirklich kann (und was nicht)
+
+Das Auschecken ist ein **Hinweis-Schloss**, kein physikalisches Dateischloss. Kurz gesagt: es hindert alle **Mini-Cloud-Wege** am Bearbeiten, aber nicht den Windows-Explorer oder andere Programme auf der Festplatte.
+
+| Wo greift das Lock? | Beispiel |
+|---------------------|----------|
+| ✅ Web-Oberflaeche | Anna kann im Browser die Datei nicht oeffnen/bearbeiten - "wird von Adam bearbeitet" |
+| ✅ Desktop-Client | Doppelklick in der Client-Ansicht -> Fehlermeldung, Datei oeffnet nicht |
+| ✅ Automatischer Upload | Hat Anna die Datei trotzdem editiert, hebt der Client sie nicht hoch, solange Adam das Lock haelt |
+| ❌ Windows-/Mac-Explorer | Anna kann die lokale Datei im Dateimanager oeffnen (ist ja eine ganz normale Datei auf der Platte) |
+| ❌ Externe Programme | Word, Excel, Notepad usw. sehen das Lock nicht - jedes Programm kann die Datei oeffnen |
+
+**Beispiel im Alltag:**
+
+1. Adam checkt `Bericht.xlsx` aus (oeffnet sie im Client)
+2. Anna hat den Ordner auch gesynct und die Datei liegt bei ihr lokal
+3. Anna versucht, sie im Browser zu oeffnen -> **blockiert**
+4. Anna versucht, sie im Client zu oeffnen -> **blockiert**
+5. Anna oeffnet sie im Explorer direkt -> **geht auf** (weil die Datei technisch ja nur eine normale Datei ist)
+6. Anna bearbeitet und speichert lokal -> Client bemerkt die Aenderung, sieht das Fremd-Lock und **haelt den Upload zurueck**
+7. Adam checkt ein: jetzt vergleicht der Client - hat Adam auch geaendert? Wenn ja, wird Annas Version zu `Bericht (Konflikt Anna 2026-04-12 143022).xlsx` und Adams Version gewinnt. Niemand verliert Daten, aber ein Mensch muss die Versionen zusammenfuehren.
+
+Das ist derselbe Ansatz wie bei Nextcloud oder Dropbox: **Konflikt-Kopie als Sicherheitsnetz**, keine kernel-tiefe Dateisperre. Der Schutz kommt ueber die Upload-Sperre - damit landet ein versehentliches Bearbeiten nie beim eigentlichen Owner.
+
+### Bauen
+
+```bash
+# Voraussetzung: Docker
+
+# Linux:
+./build.sh linux
+
+# Windows (Cross-Compile):
+./build.sh windows
+
+# macOS (nur auf Mac):
+./build.sh mac
+
+# Alle Desktop-Plattformen:
+./build.sh all-desktop
+```
+
+### Auto-Upload auf den Server
+
+Nach dem Build wird der Client automatisch auf den Cloud-Server hochgeladen und steht dort zum Download bereit.
+
+**Auf der Entwicklungsmaschine** (nicht auf dem Server!) in die `.env` eintragen:
+
+```bash
+# URL der Cloud-Instanz
+CLOUD_URL=https://cloud.example.com
+
+# SECRET_KEY des Zielservers (identisch mit SECRET_KEY in der Server-.env)
+BUILD_UPLOAD_TOKEN=der-secret-key-vom-server
+```
+
+Danach laedt `./build.sh linux` (etc.) den Build automatisch hoch. Auf der Login-Seite erscheint dann "Desktop & Mobile Clients herunterladen".
+
+**Wichtig:** `CLOUD_URL` und `BUILD_UPLOAD_TOKEN` gehoeren NUR in die `.env` der Entwicklungsmaschine, NICHT auf den Produktionsserver!
+
+### Einstellungen
+
+Einstellungen werden gespeichert in:
+- **Windows**: `%APPDATA%\MiniCloud Sync\config.json`
+- **Linux**: `~/.config/MiniCloud Sync/config.json`
+- **macOS**: `~/Library/Application Support/MiniCloud Sync/config.json`
+
+Gespeichert werden: Server-URL, Benutzername, Passwort (base64), Sync-Pfade. Bleiben bei Updates erhalten.
+
 ## Roadmap
 
-- Desktop Sync-Client (Windows, Linux, macOS) mit Full Sync + Virtual Files
+- Mobile Sync-Client (iOS, Android) mit On-Demand-Download + File Provider
-- Mobile Sync-Client (iOS, Android) mit On-Demand-Download
 - Native Passwort-Manager Clients mit Autofill und Biometrie
 - Radicale-Integration fuer vollstaendiges CalDAV/CardDAV-Protokoll
 

backend/app/__init__.py

@@ -1,13 +1,28 @@
 import os
+import time
 from pathlib import Path
 
-from flask import Flask, redirect, send_from_directory
+from flask import Flask, Response, redirect, send_from_directory
 from flask_cors import CORS
 
 from app.config import Config
 from app.extensions import db, bcrypt, migrate
 
 
+def _configure_timezone(tz_name: str) -> None:
+    """Prozess-Zeitzone setzen, sodass datetime.now(), strftime %Z etc.
+    die konfigurierte TZ verwenden. Sichere no-op wenn tzdata fehlt."""
+    if not tz_name:
+        return
+    os.environ['TZ'] = tz_name
+    tzset = getattr(time, 'tzset', None)
+    if tzset:
+        try:
+            tzset()
+        except Exception:
+            pass
+
+
 def _auto_migrate(db):
     """Add missing columns to existing tables by comparing model definitions
     with actual database schema. This handles the case where new columns are
@@ -61,6 +76,9 @@ def _auto_migrate(db):
 
 
 def create_app(config_class=Config):
+    # Zeitzone moeglichst frueh setzen - vor allen datetime.now()-Aufrufen
+    _configure_timezone(getattr(config_class, 'TIMEZONE', None) or os.environ.get('TZ'))
+
     # Check if static frontend build exists (Docker production mode)
     static_dir = Path(__file__).resolve().parent.parent / 'static'
     if static_dir.exists():
@@ -69,6 +87,9 @@ def create_app(config_class=Config):
         app = Flask(__name__)
 
     app.config.from_object(config_class)
+    # DAV-Clients setzen Trailing-Slashes uneinheitlich - daher deaktivieren
+    # wir die strikte Pruefung app-weit. Betrifft alle Blueprints.
+    app.url_map.strict_slashes = False
 
     # Ensure data directories exist
     Path(app.config['UPLOAD_PATH']).mkdir(parents=True, exist_ok=True)
@@ -88,14 +109,51 @@ def create_app(config_class=Config):
     from app.api import api_bp
     app.register_blueprint(api_bp)
 
-    # Well-known URLs for CalDAV/CardDAV auto-discovery (iOS, DAVx5, etc.)
+    from app.dav import dav_bp
-    @app.route('/.well-known/caldav')
+    app.register_blueprint(dav_bp)
-    def wellknown_caldav():
+
+    # Well-known URLs for CalDAV/CardDAV auto-discovery (iOS, DAVx5, etc.).
+    # 301-Redirect bei PROPFIND ist bei einigen Clients zickig, deshalb
+    # delegieren wir intern direkt an die DAV-Handler, statt zu redirecten.
+    from flask import request
+    from app.dav.caldav import propfind as dav_propfind, options as dav_options
+
+    def _wellknown_dav():
+        if request.method == 'PROPFIND':
+            return dav_propfind(subpath='')
+        if request.method == 'OPTIONS':
+            return dav_options()
         return redirect('/dav/', code=301)
 
-    @app.route('/.well-known/carddav')
+    app.add_url_rule(
-    def wellknown_carddav():
+        '/.well-known/caldav', view_func=_wellknown_dav,
-        return redirect('/dav/', code=301)
+        methods=['GET', 'HEAD', 'PROPFIND', 'OPTIONS'],
+        provide_automatic_options=False,
+    )
+    app.add_url_rule(
+        '/.well-known/carddav', view_func=_wellknown_dav,
+        endpoint='_wellknown_carddav',
+        methods=['GET', 'HEAD', 'PROPFIND', 'OPTIONS'],
+        provide_automatic_options=False,
+    )
+
+    # Root DAV discovery: DAVx5 und einige andere Clients probieren zuerst
+    # PROPFIND/OPTIONS auf / (nur Hostname), bevor sie /.well-known nutzen.
+    # Wir reagieren hier auch mit DAV-Properties.
+    def _root_dav():
+        if request.method == 'PROPFIND':
+            return dav_propfind(subpath='')
+        if request.method == 'OPTIONS':
+            return dav_options()
+        # GET/HEAD: SPA index handhabt das woanders - dieser View matcht nur DAV-Methoden
+        return Response('', 405)
+
+    app.add_url_rule(
+        '/', view_func=_root_dav,
+        endpoint='_root_dav',
+        methods=['PROPFIND', 'OPTIONS'],
+        provide_automatic_options=False,
+    )
 
     # iCal export (public, no auth)
     @app.route('/ical/<token>')
@@ -131,4 +189,15 @@ def create_app(config_class=Config):
         from app.services.backup_scheduler import start_backup_scheduler
         start_backup_scheduler(app)
 
+        # NTP-Offset gegen den konfigurierten Zeitserver pruefen (nicht fatal).
+        ntp_server = app.config.get('NTP_SERVER') or ''
+        if ntp_server.strip():
+            import threading
+            from app.services.ntp_check import check_and_log
+            threading.Thread(
+                target=check_and_log,
+                args=(ntp_server.strip(), app.logger),
+                daemon=True,
+            ).start()
+
     return app

backend/app/api/__init__.py

@@ -2,4 +2,4 @@ from flask import Blueprint
 
 api_bp = Blueprint('api', __name__, url_prefix='/api')
 
-from app.api import auth, users, files, calendar, contacts, email, office, passwords, backup  # noqa: E402, F401
+from app.api import auth, users, files, calendar, contacts, tasks, email, office, passwords, backup, client_downloads  # noqa: E402, F401

backend/app/api/calendar.py

@@ -1,14 +1,68 @@
+import csv
+import io
+import re
 import secrets
 import uuid
 from datetime import datetime, timezone
 
-from flask import request, jsonify
+from flask import request, jsonify, Response
 
 from app.api import api_bp
 from app.api.auth import token_required
-from app.extensions import db
+from app.extensions import db, bcrypt
 from app.models.calendar import Calendar, CalendarEvent, CalendarShare
 from app.models.user import User
+from app.services.events import notify_calendar_change
+
+
+def _calendar_recipients(cal: Calendar):
+    return [s.shared_with_id for s in CalendarShare.query.filter_by(calendar_id=cal.id).all()]
+
+
+def _redact_if_private(event_dict: dict, is_owner: bool) -> dict:
+    """For shared viewers, strip summary/description/location from private
+    events so only the time slot remains visible."""
+    if is_owner or not event_dict.get('is_private'):
+        return event_dict
+    d = dict(event_dict)
+    d['summary'] = 'Privat'
+    d['description'] = None
+    d['location'] = None
+    return d
+
+
+def _redact_vevent(raw: str) -> str:
+    """Strip SUMMARY/DESCRIPTION/LOCATION from a VEVENT block and set
+    CLASS:PRIVATE. Used for shared iCal exports and CalDAV responses."""
+    if not raw:
+        return raw
+    import re as _re
+    out_lines = []
+    has_class = False
+    for line in raw.split('\n'):
+        stripped = line.rstrip('\r')
+        upper = stripped.split(':', 1)[0].split(';', 1)[0].upper()
+        if upper == 'SUMMARY':
+            out_lines.append('SUMMARY:Privat')
+        elif upper in ('DESCRIPTION', 'LOCATION'):
+            continue
+        elif upper == 'CLASS':
+            has_class = True
+            out_lines.append('CLASS:PRIVATE')
+        else:
+            out_lines.append(stripped)
+    if not has_class:
+        # Inject CLASS right after UID if possible, else before END:VEVENT
+        for i, l in enumerate(out_lines):
+            if l.startswith('UID:'):
+                out_lines.insert(i + 1, 'CLASS:PRIVATE')
+                break
+        else:
+            for i, l in enumerate(out_lines):
+                if l.upper().startswith('END:VEVENT'):
+                    out_lines.insert(i, 'CLASS:PRIVATE')
+                    break
+    return '\r\n'.join(out_lines)
 
 
 def _get_calendar_or_err(cal_id, user, need_write=False):
@@ -49,7 +103,14 @@ def list_calendars():
             calendar_id=c.id, shared_with_id=user.id
         ).first()
         d['permission'] = share.permission if share else 'read'
+        # Per-user color override: the owner's color is kept in 'owner_color'
+        # so the UI can show both, and 'color' reflects what this user picked.
+        d['owner_color'] = c.color
+        if share and share.color:
+            d['color'] = share.color
         d['owner_name'] = c.owner.username
+        d['owner_full_name'] = c.owner.full_name
+        d['owner_display_name'] = c.owner.display_name
         result.append(d)
 
     return jsonify(result), 200
@@ -95,6 +156,33 @@ def update_calendar(cal_id):
     return jsonify(cal.to_dict()), 200
 
 
+@api_bp.route('/calendars/<int:cal_id>/my-color', methods=['PUT'])
+@token_required
+def set_my_calendar_color(cal_id):
+    """Personal display color for a shared calendar. Doesn't affect the
+    owner's calendar color or any other user's view."""
+    user = request.current_user
+    cal = db.session.get(Calendar, cal_id)
+    if not cal:
+        return jsonify({'error': 'Nicht gefunden'}), 404
+
+    color = (request.get_json() or {}).get('color', '').strip()
+
+    if cal.owner_id == user.id:
+        # Owner -> update the calendar itself
+        if color:
+            cal.color = color
+        db.session.commit()
+        return jsonify({'color': cal.color}), 200
+
+    share = CalendarShare.query.filter_by(calendar_id=cal_id, shared_with_id=user.id).first()
+    if not share:
+        return jsonify({'error': 'Kein Zugriff'}), 403
+    share.color = color or None
+    db.session.commit()
+    return jsonify({'color': share.color or cal.color}), 200
+
+
 @api_bp.route('/calendars/<int:cal_id>', methods=['DELETE'])
 @token_required
 def delete_calendar(cal_id):
@@ -103,8 +191,12 @@ def delete_calendar(cal_id):
     if not cal or cal.owner_id != user.id:
         return jsonify({'error': 'Nicht gefunden oder keine Berechtigung'}), 404
 
+    recipients = _calendar_recipients(cal)
+    owner_id = cal.owner_id
+    cal_id = cal.id
     db.session.delete(cal)
     db.session.commit()
+    notify_calendar_change(owner_id, cal_id, 'deleted', shared_with=recipients)
     return jsonify({'message': 'Kalender geloescht'}), 200
 
 
@@ -122,21 +214,183 @@ def list_events(cal_id):
     end = request.args.get('end')
 
     query = CalendarEvent.query.filter_by(calendar_id=cal_id)
+    # Wiederkehrende Termine duerfen nicht per Range gefiltert werden -
+    # die FullCalendar-RRULE-Plugin-Expansion im Frontend braucht den
+    # Master-Event auch wenn dessen dtstart vor dem sichtbaren Bereich liegt.
     if start:
         try:
             start_dt = datetime.fromisoformat(start)
-            query = query.filter(CalendarEvent.dtend >= start_dt)
+            query = query.filter(db.or_(
+                CalendarEvent.recurrence_rule.isnot(None),
+                CalendarEvent.dtend >= start_dt,
+            ))
         except ValueError:
             pass
     if end:
         try:
             end_dt = datetime.fromisoformat(end)
-            query = query.filter(CalendarEvent.dtstart <= end_dt)
+            query = query.filter(db.or_(
+                CalendarEvent.recurrence_rule.isnot(None),
+                CalendarEvent.dtstart <= end_dt,
+            ))
         except ValueError:
             pass
 
     events = query.order_by(CalendarEvent.dtstart).all()
-    return jsonify([e.to_dict() for e in events]), 200
+    is_owner = (cal.owner_id == user.id)
+    return jsonify([_redact_if_private(e.to_dict(), is_owner) for e in events]), 200
+
+
+@api_bp.route('/calendars/<int:cal_id>/export', methods=['GET'])
+@token_required
+def export_calendar(cal_id):
+    """Export VEVENTs als .ics oder .csv."""
+    user = request.current_user
+    cal, err = _get_calendar_or_err(cal_id, user)
+    if err:
+        return err
+    fmt = (request.args.get('format') or 'ics').lower()
+    events = CalendarEvent.query.filter_by(calendar_id=cal_id).order_by(CalendarEvent.dtstart).all()
+    safe_name = re.sub(r'[^A-Za-z0-9._-]+', '_', cal.name or 'kalender') or 'kalender'
+
+    if fmt == 'ics':
+        lines = ['BEGIN:VCALENDAR', 'VERSION:2.0', 'PRODID:-//Mini-Cloud//DE', 'CALSCALE:GREGORIAN']
+        for e in events:
+            block = (e.ical_data or '').strip()
+            if not block:
+                block = _build_vevent(e.uid, e.summary or '', e.dtstart, e.dtend,
+                                      e.all_day, e.description or '', e.location or '',
+                                      e.recurrence_rule or '',
+                                      (e.exdates or '').split(',') if e.exdates else None)
+            # Make sure block contains BEGIN/END VEVENT
+            if 'BEGIN:VEVENT' not in block.upper():
+                continue
+            lines.append(block.strip())
+        lines.append('END:VCALENDAR')
+        body = '\r\n'.join(lines) + '\r\n'
+        return Response(
+            body, mimetype='text/calendar; charset=utf-8',
+            headers={'Content-Disposition': f'attachment; filename="{safe_name}.ics"'},
+        )
+    if fmt == 'csv':
+        out = io.StringIO()
+        cols = ['summary', 'dtstart', 'dtend', 'all_day', 'location',
+                'description', 'recurrence_rule', 'uid']
+        w = csv.writer(out, delimiter=';', quoting=csv.QUOTE_ALL)
+        w.writerow(cols)
+        for e in events:
+            w.writerow([
+                e.summary or '',
+                e.dtstart.isoformat() if e.dtstart else '',
+                e.dtend.isoformat() if e.dtend else '',
+                '1' if e.all_day else '0',
+                e.location or '',
+                (e.description or '').replace('\r\n', ' ').replace('\n', ' '),
+                e.recurrence_rule or '',
+                e.uid or '',
+            ])
+        return Response(
+            '\ufeff' + out.getvalue(), mimetype='text/csv; charset=utf-8',
+            headers={'Content-Disposition': f'attachment; filename="{safe_name}.csv"'},
+        )
+    return jsonify({'error': 'Unbekanntes Format'}), 400
+
+
+@api_bp.route('/calendars/<int:cal_id>/import', methods=['POST'])
+@token_required
+def import_calendar(cal_id):
+    """Import .ics oder .csv -> Termine ins Kalender."""
+    from app.dav.caldav import _parse_vevent, _extract_vevent_block
+    user = request.current_user
+    cal, err = _get_calendar_or_err(cal_id, user, need_write=True)
+    if err:
+        return err
+    file = request.files.get('file')
+    if not file:
+        return jsonify({'error': 'Keine Datei'}), 400
+    raw = file.read()
+    name = (file.filename or '').lower()
+    try:
+        text = raw.decode('utf-8-sig')
+    except UnicodeDecodeError:
+        text = raw.decode('latin-1', errors='replace')
+
+    imported = 0
+    skipped = 0
+
+    def _save(parsed: dict, ical_block: str | None = None):
+        nonlocal imported, skipped
+        if not parsed.get('summary') or not parsed.get('dtstart'):
+            skipped += 1
+            return
+        uid = parsed.get('uid') or str(uuid.uuid4())
+        existing = CalendarEvent.query.filter_by(calendar_id=cal_id, uid=uid).first()
+        ev = existing or CalendarEvent(calendar_id=cal_id, uid=uid, ical_data='')
+        ev.summary = parsed.get('summary') or '(ohne Titel)'
+        ev.description = parsed.get('description')
+        ev.location = parsed.get('location')
+        ev.dtstart = parsed.get('dtstart')
+        ev.dtend = parsed.get('dtend')
+        ev.all_day = parsed.get('all_day', False)
+        ev.recurrence_rule = parsed.get('rrule')
+        ev.exdates = ','.join(parsed.get('exdates', [])) or None
+        ev.ical_data = (ical_block or '').strip() or _build_vevent(
+            uid, ev.summary, ev.dtstart, ev.dtend, ev.all_day,
+            ev.description or '', ev.location or '', ev.recurrence_rule or '',
+            (ev.exdates or '').split(',') if ev.exdates else None,
+        )
+        ev.updated_at = datetime.now(timezone.utc)
+        if not existing:
+            db.session.add(ev)
+        imported += 1
+
+    if name.endswith('.csv') or (b';' in raw[:200] and b'BEGIN:VCALENDAR' not in raw[:200]):
+        reader = csv.DictReader(io.StringIO(text), delimiter=';')
+        if not reader.fieldnames or len(reader.fieldnames) < 2:
+            reader = csv.DictReader(io.StringIO(text), delimiter=',')
+        for row in reader:
+            row = {k.strip().lower(): (v or '').strip() for k, v in row.items() if k}
+            try:
+                dtstart = datetime.fromisoformat(row.get('dtstart') or row.get('start') or '')
+            except (ValueError, TypeError):
+                skipped += 1
+                continue
+            try:
+                dtend = datetime.fromisoformat(row.get('dtend') or row.get('end') or '') if (row.get('dtend') or row.get('end')) else None
+            except ValueError:
+                dtend = None
+            parsed = {
+                'uid': row.get('uid'),
+                'summary': row.get('summary') or row.get('titel') or row.get('title'),
+                'description': row.get('description') or row.get('beschreibung'),
+                'location': row.get('location') or row.get('ort'),
+                'dtstart': dtstart,
+                'dtend': dtend,
+                'all_day': (row.get('all_day') or '').lower() in ('1', 'true', 'ja', 'yes'),
+                'rrule': row.get('recurrence_rule') or row.get('rrule'),
+                'exdates': [],
+            }
+            _save(parsed)
+    else:
+        # iCal: Kalender-Datei mit beliebig vielen VEVENTs
+        blocks = re.findall(r'BEGIN:VEVENT.*?END:VEVENT', text, flags=re.DOTALL | re.IGNORECASE)
+        if not blocks:
+            return jsonify({'error': 'Keine VEVENT-Daten gefunden'}), 400
+        for block in blocks:
+            try:
+                parsed = _parse_vevent(block)
+            except Exception:
+                parsed = None
+            if not parsed:
+                skipped += 1
+                continue
+            _save(parsed, ical_block=block)
+
+    db.session.commit()
+    if imported:
+        notify_calendar_change(cal.owner_id, cal.id, 'event',
+                               shared_with=_calendar_recipients(cal))
+    return jsonify({'imported': imported, 'skipped': skipped}), 200
 
 
 @api_bp.route('/calendars/<int:cal_id>/events', methods=['POST'])
@@ -166,24 +420,30 @@ def create_event(cal_id):
         return jsonify({'error': 'Ungueltiges Datumsformat'}), 400
 
     event_uid = str(uuid.uuid4())
+    description = (data.get('description') or '').strip()
+    location = (data.get('location') or '').strip()
+    rrule = (data.get('recurrence_rule') or '').strip()
 
-    # Build simple iCal data
     ical_data = _build_ical(event_uid, summary, dtstart_dt, dtend_dt, all_day,
-                            data.get('description', ''), data.get('location', ''),
+                            description, location, rrule, None)
-                            data.get('recurrence_rule', ''))
 
     event = CalendarEvent(
         calendar_id=cal_id,
         uid=event_uid,
         ical_data=ical_data,
         summary=summary,
+        description=description or None,
+        location=location or None,
         dtstart=dtstart_dt,
         dtend=dtend_dt,
         all_day=all_day,
-        recurrence_rule=data.get('recurrence_rule'),
+        recurrence_rule=rrule or None,
+        is_private=bool(data.get('is_private', False)),
     )
     db.session.add(event)
     db.session.commit()
+    notify_calendar_change(cal.owner_id, cal.id, 'event',
+                           shared_with=_calendar_recipients(cal))
     return jsonify(event.to_dict()), 201
 
 
@@ -202,14 +462,20 @@ def update_event(event_id):
     data = request.get_json()
     if 'summary' in data:
         event.summary = data['summary'].strip()
+    if 'description' in data:
+        event.description = (data['description'] or '').strip() or None
+    if 'location' in data:
+        event.location = (data['location'] or '').strip() or None
     if 'dtstart' in data:
         event.dtstart = datetime.fromisoformat(data['dtstart'])
     if 'dtend' in data:
-        event.dtend = datetime.fromisoformat(data['dtend'])
+        event.dtend = datetime.fromisoformat(data['dtend']) if data['dtend'] else None
     if 'all_day' in data:
         event.all_day = data['all_day']
     if 'recurrence_rule' in data:
-        event.recurrence_rule = data['recurrence_rule']
+        event.recurrence_rule = (data['recurrence_rule'] or '').strip() or None
+    if 'is_private' in data:
+        event.is_private = bool(data['is_private'])
     if 'calendar_id' in data:
         new_cal, cerr = _get_calendar_or_err(data['calendar_id'], user, need_write=True)
         if cerr:
@@ -218,14 +484,90 @@ def update_event(event_id):
 
     event.ical_data = _build_ical(
         event.uid, event.summary, event.dtstart, event.dtend,
-        event.all_day, data.get('description', ''), data.get('location', ''),
+        event.all_day, event.description or '', event.location or '',
-        event.recurrence_rule or ''
+        event.recurrence_rule or '',
+        event.exdates.split(',') if event.exdates else None,
     )
     event.updated_at = datetime.now(timezone.utc)
     db.session.commit()
+    notify_calendar_change(cal.owner_id, cal.id, 'event',
+                           shared_with=_calendar_recipients(cal))
     return jsonify(event.to_dict()), 200
 
 
+@api_bp.route('/events/<int:event_id>/exception', methods=['POST'])
+@token_required
+def add_event_exception(event_id):
+    """Exclude a single occurrence of a recurring event ("nur dieser Termin").
+    Optionally creates a standalone replacement event for that date."""
+    user = request.current_user
+    event = db.session.get(CalendarEvent, event_id)
+    if not event:
+        return jsonify({'error': 'Event nicht gefunden'}), 404
+
+    cal, err = _get_calendar_or_err(event.calendar_id, user, need_write=True)
+    if err:
+        return err
+    if not event.recurrence_rule:
+        return jsonify({'error': 'Kein Serientermin'}), 400
+
+    data = request.get_json()
+    occurrence_date = data.get('occurrence_date')  # ISO date or datetime
+    if not occurrence_date:
+        return jsonify({'error': 'occurrence_date erforderlich'}), 400
+
+    # Normalize to YYYY-MM-DD for storage key
+    try:
+        parsed = datetime.fromisoformat(occurrence_date.replace('Z', '+00:00'))
+        key = parsed.strftime('%Y-%m-%d' if event.all_day else '%Y-%m-%dT%H:%M:%S')
+    except ValueError:
+        key = occurrence_date
+
+    existing = (event.exdates or '').split(',') if event.exdates else []
+    if key not in existing:
+        existing.append(key)
+    event.exdates = ','.join(filter(None, existing))
+
+    # Optional: create replacement single event
+    replacement = None
+    if data.get('replacement'):
+        r = data['replacement']
+        rep_uid = str(uuid.uuid4())
+        rep_start = datetime.fromisoformat(r['dtstart'])
+        rep_end = datetime.fromisoformat(r['dtend']) if r.get('dtend') else rep_start
+        replacement = CalendarEvent(
+            calendar_id=event.calendar_id,
+            uid=rep_uid,
+            summary=r.get('summary', event.summary),
+            description=r.get('description', event.description),
+            location=r.get('location', event.location),
+            dtstart=rep_start,
+            dtend=rep_end,
+            all_day=r.get('all_day', event.all_day),
+            recurrence_rule=None,
+            ical_data='',
+        )
+        replacement.ical_data = _build_ical(
+            rep_uid, replacement.summary, rep_start, rep_end,
+            replacement.all_day, replacement.description or '',
+            replacement.location or '', '',
+        )
+        db.session.add(replacement)
+
+    event.ical_data = _build_ical(
+        event.uid, event.summary, event.dtstart, event.dtend,
+        event.all_day, event.description or '', event.location or '',
+        event.recurrence_rule or '',
+        event.exdates.split(',') if event.exdates else None,
+    )
+    event.updated_at = datetime.now(timezone.utc)
+    db.session.commit()
+    return jsonify({
+        'event': event.to_dict(),
+        'replacement': replacement.to_dict() if replacement else None,
+    }), 200
+
+
 @api_bp.route('/events/<int:event_id>', methods=['DELETE'])
 @token_required
 def delete_event(event_id):
@@ -238,8 +580,12 @@ def delete_event(event_id):
     if err:
         return err
 
+    cal = db.session.get(Calendar, event.calendar_id)
     db.session.delete(event)
     db.session.commit()
+    if cal:
+        notify_calendar_change(cal.owner_id, cal.id, 'event',
+                               shared_with=_calendar_recipients(cal))
     return jsonify({'message': 'Event geloescht'}), 200
 
 
@@ -287,6 +633,9 @@ def share_calendar(cal_id):
         except Exception:
             pass
 
+    notify_calendar_change(cal.owner_id, cal.id, 'share',
+                           shared_with=[target.id, *_calendar_recipients(cal)])
+
     return jsonify({'message': f'Kalender mit {username} geteilt'}), 200
 
 
@@ -319,8 +668,11 @@ def remove_calendar_share(cal_id, share_id):
     if not share or share.calendar_id != cal_id:
         return jsonify({'error': 'Freigabe nicht gefunden'}), 404
 
+    target_id = share.shared_with_id
     db.session.delete(share)
     db.session.commit()
+    notify_calendar_change(cal.owner_id, cal.id, 'share',
+                           shared_with=[target_id, *_calendar_recipients(cal)])
     return jsonify({'message': 'Freigabe entfernt'}), 200
 
 
@@ -334,19 +686,58 @@ def generate_ical_link(cal_id):
     if not cal or cal.owner_id != user.id:
         return jsonify({'error': 'Nicht gefunden'}), 404
 
-    cal.ical_token = secrets.token_urlsafe(32)
+    data = request.get_json(silent=True) or {}
+    password = (data.get('password') or '').strip()
+
+    if not cal.ical_token:
+        cal.ical_token = secrets.token_urlsafe(32)
+    if password:
+        cal.ical_password_hash = bcrypt.generate_password_hash(password).decode('utf-8')
+    elif data.get('clear_password'):
+        cal.ical_password_hash = None
+
     db.session.commit()
     return jsonify({
         'ical_url': f'/ical/{cal.ical_token}',
         'token': cal.ical_token,
+        'has_password': bool(cal.ical_password_hash),
     }), 200
 
 
+@api_bp.route('/calendars/<int:cal_id>/ical-link', methods=['DELETE'])
+@token_required
+def revoke_ical_link(cal_id):
+    user = request.current_user
+    cal = db.session.get(Calendar, cal_id)
+    if not cal or cal.owner_id != user.id:
+        return jsonify({'error': 'Nicht gefunden'}), 404
+    cal.ical_token = None
+    cal.ical_password_hash = None
+    db.session.commit()
+    return jsonify({'message': 'Link zurueckgezogen'}), 200
+
+
+def _basic_auth_challenge():
+    return Response(
+        'Kalender erfordert Passwort', 401,
+        {'WWW-Authenticate': 'Basic realm="Mini-Cloud Kalender"'}
+    )
+
+
 def ical_export(token):
     cal = Calendar.query.filter_by(ical_token=token).first()
     if not cal:
         return jsonify({'error': 'Nicht gefunden'}), 404
 
+    # Password protection via HTTP Basic (compatible with DAVx5, Apple Cal,
+    # Thunderbird, curl, etc.). Username is ignored.
+    if cal.ical_password_hash:
+        auth = request.authorization
+        if not auth or not auth.password:
+            return _basic_auth_challenge()
+        if not bcrypt.check_password_hash(cal.ical_password_hash, auth.password):
+            return _basic_auth_challenge()
+
     events = CalendarEvent.query.filter_by(calendar_id=cal.id).all()
 
     lines = [
@@ -357,13 +748,14 @@ def ical_export(token):
     ]
     for e in events:
         if e.ical_data:
-            # Extract VEVENT from stored ical_data
+            block = _redact_vevent(e.ical_data) if e.is_private else e.ical_data
-            lines.append(e.ical_data)
+            lines.append(block)
+        elif e.is_private:
+            lines.append(_build_vevent(e.uid, 'Privat', e.dtstart, e.dtend, e.all_day))
         else:
             lines.append(_build_vevent(e.uid, e.summary, e.dtstart, e.dtend, e.all_day))
     lines.append('END:VCALENDAR')
 
-    from flask import Response
     return Response(
         '\r\n'.join(lines),
         mimetype='text/calendar',
@@ -379,7 +771,9 @@ def _format_dt(dt, all_day=False):
     return dt.strftime('%Y%m%dT%H%M%SZ')
 
 
-def _build_vevent(uid, summary, dtstart, dtend, all_day, description='', location='', rrule=''):
+def _build_vevent(uid, summary, dtstart, dtend, all_day, description='', location='', rrule='', exdates=None):
+    if not dtend:
+        dtend = dtstart
     lines = [
         'BEGIN:VEVENT',
         f'UID:{uid}',
@@ -397,10 +791,21 @@ def _build_vevent(uid, summary, dtstart, dtend, all_day, description='', locatio
         lines.append(f'LOCATION:{location}')
     if rrule:
         lines.append(f'RRULE:{rrule}')
+    if exdates:
+        for ex in exdates:
+            if all_day:
+                lines.append(f'EXDATE;VALUE=DATE:{ex.replace("-", "")}')
+            else:
+                # Convert ISO datetime (with or without TZ) into YYYYMMDDTHHMMSSZ
+                try:
+                    dt = datetime.fromisoformat(ex.replace('Z', '+00:00'))
+                    lines.append(f'EXDATE:{dt.strftime("%Y%m%dT%H%M%SZ")}')
+                except ValueError:
+                    pass
     lines.append(f'DTSTAMP:{datetime.now(timezone.utc).strftime("%Y%m%dT%H%M%SZ")}')
     lines.append('END:VEVENT')
     return '\r\n'.join(lines)
 
 
-def _build_ical(uid, summary, dtstart, dtend, all_day, description='', location='', rrule=''):
+def _build_ical(uid, summary, dtstart, dtend, all_day, description='', location='', rrule='', exdates=None):
-    return _build_vevent(uid, summary, dtstart, dtend, all_day, description, location, rrule)
+    return _build_vevent(uid, summary, dtstart, dtend, all_day, description, location, rrule, exdates)

backend/app/api/client_downloads.py

@@ -0,0 +1,126 @@
+"""Client download management - upload builds, serve downloads."""
+import os
+from pathlib import Path
+
+from flask import request, jsonify, send_from_directory, current_app
+
+from app.api import api_bp
+
+# Supported platforms and their file extensions
+PLATFORMS = {
+    'linux': {'name': 'Linux', 'icon': 'pi-desktop', 'extensions': ['.AppImage', '.deb', '']},
+    'windows': {'name': 'Windows', 'icon': 'pi-microsoft', 'extensions': ['.msi', '.exe']},
+    'mac': {'name': 'macOS', 'icon': 'pi-apple', 'extensions': ['.dmg']},
+    'android': {'name': 'Android', 'icon': 'pi-android', 'extensions': ['.apk']},
+    'ios': {'name': 'iOS', 'icon': 'pi-apple', 'extensions': ['.ipa']},
+}
+
+
+def _clients_dir():
+    """Get the client downloads directory."""
+    base = Path(current_app.config.get('UPLOAD_PATH', '/app/data/files')).parent
+    d = base / 'client-downloads'
+    d.mkdir(parents=True, exist_ok=True)
+    return d
+
+
+def _verify_build_token():
+    """Verify the build upload token from header or query param."""
+    token = request.headers.get('X-Build-Token', '') or request.args.get('build_token', '')
+    if not token:
+        return False
+    # Accept SECRET_KEY or JWT_SECRET_KEY
+    secret = os.environ.get('SECRET_KEY', '')
+    jwt_secret = os.environ.get('JWT_SECRET_KEY', '')
+    return token == secret or token == jwt_secret
+
+
+# --- Public: list available clients ---
+
+@api_bp.route('/clients', methods=['GET'])
+def list_clients():
+    """List available client downloads (public, no auth needed)."""
+    clients_dir = _clients_dir()
+    available = []
+
+    for platform, info in PLATFORMS.items():
+        platform_dir = clients_dir / platform
+        if not platform_dir.exists():
+            continue
+
+        files = sorted(platform_dir.iterdir(), key=lambda f: f.stat().st_mtime, reverse=True)
+        if not files:
+            continue
+
+        # Take the newest file
+        latest = files[0]
+        available.append({
+            'platform': platform,
+            'name': info['name'],
+            'icon': info['icon'],
+            'filename': latest.name,
+            'size': latest.stat().st_size,
+            'updated_at': latest.stat().st_mtime,
+            'download_url': f'/api/clients/{platform}/download',
+        })
+
+    return jsonify({
+        'clients': available,
+        'has_clients': len(available) > 0,
+    }), 200
+
+
+@api_bp.route('/clients/<platform>/download', methods=['GET'])
+def download_client(platform):
+    """Download the latest client for a platform (public, no auth)."""
+    if platform not in PLATFORMS:
+        return jsonify({'error': 'Unbekannte Plattform'}), 404
+
+    clients_dir = _clients_dir()
+    platform_dir = clients_dir / platform
+
+    if not platform_dir.exists():
+        return jsonify({'error': 'Kein Client fuer diese Plattform verfuegbar'}), 404
+
+    files = sorted(platform_dir.iterdir(), key=lambda f: f.stat().st_mtime, reverse=True)
+    if not files:
+        return jsonify({'error': 'Kein Client verfuegbar'}), 404
+
+    latest = files[0]
+    return send_from_directory(str(platform_dir), latest.name, as_attachment=True)
+
+
+# --- Build upload (authenticated with BUILD_UPLOAD_TOKEN) ---
+
+@api_bp.route('/clients/<platform>/upload', methods=['POST'])
+def upload_client(platform):
+    """Upload a new client build. Authenticated with BUILD_UPLOAD_TOKEN."""
+    if not _verify_build_token():
+        return jsonify({'error': 'Ungueltiger Build-Token'}), 403
+
+    if platform not in PLATFORMS:
+        return jsonify({'error': 'Unbekannte Plattform'}), 404
+
+    if 'file' not in request.files:
+        return jsonify({'error': 'Keine Datei gesendet'}), 400
+
+    upload = request.files['file']
+    if not upload.filename:
+        return jsonify({'error': 'Leerer Dateiname'}), 400
+
+    clients_dir = _clients_dir()
+    platform_dir = clients_dir / platform
+    platform_dir.mkdir(parents=True, exist_ok=True)
+
+    # Remove old files for this platform (keep only latest)
+    for old_file in platform_dir.iterdir():
+        old_file.unlink()
+
+    dest = platform_dir / upload.filename
+    upload.save(str(dest))
+
+    return jsonify({
+        'message': f'{PLATFORMS[platform]["name"]} Client hochgeladen',
+        'filename': upload.filename,
+        'size': dest.stat().st_size,
+    }), 200

backend/app/api/contacts.py

@@ -1,13 +1,35 @@
+import csv
+import io
+import json
+import re
 import uuid
+import zipfile
 from datetime import datetime, timezone
 
-from flask import request, jsonify
+from flask import request, jsonify, Response
 
 from app.api import api_bp
 from app.api.auth import token_required
 from app.extensions import db
 from app.models.contact import AddressBook, Contact, AddressBookShare
 from app.models.user import User
+from app.services.events import broadcaster
+
+
+def _notify_addressbook(owner_id: int, book_id: int, change: str, shared_with=()):
+    """SSE event for a vcard or share change. Re-uses the calendar event
+    infrastructure with a separate 'addressbook' type."""
+    recipients = [owner_id, *shared_with]
+    broadcaster.publish(recipients, {
+        'type': 'addressbook',
+        'change': change,
+        'address_book_id': book_id,
+    })
+
+
+def _book_recipients(book: AddressBook):
+    return [s.shared_with_id for s in
+            AddressBookShare.query.filter_by(address_book_id=book.id).all()]
 
 
 def _get_addressbook_or_err(book_id, user, need_write=False):
@@ -26,7 +48,224 @@ def _get_addressbook_or_err(book_id, user, need_write=False):
     return book, None
 
 
-# --- Address Books ---
+# ---------------------------------------------------------------------------
+# vCard helpers
+# ---------------------------------------------------------------------------
+
+def _escape(s):
+    if s is None:
+        return ''
+    return str(s).replace('\\', '\\\\').replace(',', '\\,').replace(';', '\\;').replace('\n', '\\n')
+
+
+def _unescape(s):
+    if not s:
+        return ''
+    return s.replace('\\n', '\n').replace('\\;', ';').replace('\\,', ',').replace('\\\\', '\\')
+
+
+def _apply_fields_to_contact(contact: Contact, data: dict):
+    """Copy fields from a JSON request into a Contact model instance."""
+    for field in ('prefix', 'first_name', 'middle_name', 'last_name', 'suffix',
+                  'nickname', 'organization', 'department', 'job_title',
+                  'notes', 'photo', 'birthday', 'anniversary'):
+        if field in data:
+            value = data[field]
+            setattr(contact, field, (value.strip() if isinstance(value, str) else value) or None)
+
+    if 'display_name' in data:
+        contact.display_name = (data['display_name'] or '').strip() or None
+
+    for jsonfield in ('emails', 'phones', 'addresses', 'websites', 'impp', 'categories'):
+        if jsonfield in data:
+            value = data[jsonfield] or []
+            setattr(contact, jsonfield, json.dumps(value) if value else None)
+
+    # Denormalised primary fields for list display
+    emails = data.get('emails') if 'emails' in data else json.loads(contact.emails) if contact.emails else []
+    phones = data.get('phones') if 'phones' in data else json.loads(contact.phones) if contact.phones else []
+    contact.primary_email = (emails[0]['value'] if emails else None)
+    contact.primary_phone = (phones[0]['value'] if phones else None)
+    # Legacy columns
+    contact.email = contact.primary_email
+    contact.phone = contact.primary_phone
+
+    # Compose display name if not provided
+    if not contact.display_name:
+        parts = [contact.prefix, contact.first_name, contact.middle_name,
+                 contact.last_name, contact.suffix]
+        contact.display_name = ' '.join(p for p in parts if p) or contact.organization or None
+
+
+def _build_vcard(contact: Contact) -> str:
+    """Render a Contact into vCard 3.0 text."""
+    lines = ['BEGIN:VCARD', 'VERSION:3.0', f'UID:{contact.uid}']
+
+    if contact.display_name:
+        lines.append(f'FN:{_escape(contact.display_name)}')
+
+    # N: lastname;firstname;middle;prefix;suffix
+    n_parts = [_escape(contact.last_name), _escape(contact.first_name),
+               _escape(contact.middle_name), _escape(contact.prefix),
+               _escape(contact.suffix)]
+    if any(n_parts):
+        lines.append('N:' + ';'.join(n_parts))
+
+    if contact.nickname:
+        lines.append(f'NICKNAME:{_escape(contact.nickname)}')
+
+    if contact.organization or contact.department:
+        lines.append(f'ORG:{_escape(contact.organization or "")};{_escape(contact.department or "")}')
+    if contact.job_title:
+        lines.append(f'TITLE:{_escape(contact.job_title)}')
+
+    for e in (json.loads(contact.emails) if contact.emails else []):
+        typ = (e.get('type') or 'home').upper()
+        lines.append(f'EMAIL;TYPE={typ}:{_escape(e.get("value", ""))}')
+    for p in (json.loads(contact.phones) if contact.phones else []):
+        typ = (p.get('type') or 'cell').upper()
+        lines.append(f'TEL;TYPE={typ}:{_escape(p.get("value", ""))}')
+    for a in (json.loads(contact.addresses) if contact.addresses else []):
+        typ = (a.get('type') or 'home').upper()
+        # ADR: po_box;extended;street;city;region;postal_code;country
+        parts = [_escape(a.get('po_box', '')), '', _escape(a.get('street', '')),
+                 _escape(a.get('city', '')), _escape(a.get('region', '')),
+                 _escape(a.get('postal_code', '')), _escape(a.get('country', ''))]
+        lines.append(f'ADR;TYPE={typ}:' + ';'.join(parts))
+    for w in (json.loads(contact.websites) if contact.websites else []):
+        typ = (w.get('type') or '').upper()
+        tag = f'URL;TYPE={typ}' if typ else 'URL'
+        lines.append(f'{tag}:{_escape(w.get("value", ""))}')
+    for i in (json.loads(contact.impp) if contact.impp else []):
+        proto = (i.get('protocol') or 'xmpp').lower()
+        lines.append(f'IMPP:{proto}:{_escape(i.get("value", ""))}')
+
+    if contact.birthday:
+        lines.append(f'BDAY:{contact.birthday}')
+    if contact.anniversary:
+        lines.append(f'ANNIVERSARY:{contact.anniversary}')
+
+    cats = json.loads(contact.categories) if contact.categories else []
+    if cats:
+        lines.append('CATEGORIES:' + ','.join(_escape(c) for c in cats))
+
+    if contact.notes:
+        lines.append(f'NOTE:{_escape(contact.notes)}')
+
+    if contact.photo:
+        # Photo can be a data: URL or http URL. In vCard 3.0 we use PHOTO;VALUE=uri.
+        lines.append(f'PHOTO;VALUE=uri:{contact.photo}')
+
+    lines.append(f'REV:{datetime.now(timezone.utc).strftime("%Y%m%dT%H%M%SZ")}')
+    lines.append('END:VCARD')
+    return '\r\n'.join(lines)
+
+
+def _unfold_vcard(raw: str):
+    """Undo RFC 6350 line folding (continuation lines start with space/tab)."""
+    lines = []
+    for line in raw.replace('\r\n', '\n').split('\n'):
+        if line.startswith((' ', '\t')) and lines:
+            lines[-1] += line[1:]
+        else:
+            lines.append(line)
+    return lines
+
+
+def parse_vcard(raw: str) -> dict:
+    """Parse a VCARD text into a dict of fields usable by _apply_fields_to_contact.
+    Returns dict with keys matching contact fields + 'uid'."""
+    result = {
+        'emails': [], 'phones': [], 'addresses': [],
+        'websites': [], 'impp': [], 'categories': [],
+    }
+    for line in _unfold_vcard(raw):
+        if ':' not in line:
+            continue
+        key, _, value = line.partition(':')
+        parts = key.split(';')
+        name = parts[0].upper()
+        params = {}
+        for p in parts[1:]:
+            if '=' in p:
+                k, v = p.split('=', 1)
+                params[k.upper()] = v.upper()
+
+        if name == 'UID':
+            result['uid'] = value.strip()
+        elif name == 'FN':
+            result['display_name'] = _unescape(value)
+        elif name == 'N':
+            fields = value.split(';')
+            if len(fields) >= 5:
+                result['last_name'] = _unescape(fields[0]) or None
+                result['first_name'] = _unescape(fields[1]) or None
+                result['middle_name'] = _unescape(fields[2]) or None
+                result['prefix'] = _unescape(fields[3]) or None
+                result['suffix'] = _unescape(fields[4]) or None
+        elif name == 'NICKNAME':
+            result['nickname'] = _unescape(value)
+        elif name == 'ORG':
+            fields = value.split(';')
+            result['organization'] = _unescape(fields[0]) if fields else None
+            if len(fields) > 1:
+                result['department'] = _unescape(fields[1]) or None
+        elif name == 'TITLE':
+            result['job_title'] = _unescape(value)
+        elif name == 'EMAIL':
+            result['emails'].append({
+                'type': (params.get('TYPE') or 'home').lower(),
+                'value': _unescape(value),
+            })
+        elif name == 'TEL':
+            result['phones'].append({
+                'type': (params.get('TYPE') or 'cell').lower(),
+                'value': _unescape(value),
+            })
+        elif name == 'ADR':
+            fields = value.split(';')
+            pad = fields + [''] * (7 - len(fields))
+            result['addresses'].append({
+                'type': (params.get('TYPE') or 'home').lower(),
+                'po_box': _unescape(pad[0]),
+                'street': _unescape(pad[2]),
+                'city': _unescape(pad[3]),
+                'region': _unescape(pad[4]),
+                'postal_code': _unescape(pad[5]),
+                'country': _unescape(pad[6]),
+            })
+        elif name == 'URL':
+            result['websites'].append({
+                'type': (params.get('TYPE') or '').lower(),
+                'value': _unescape(value),
+            })
+        elif name == 'IMPP':
+            proto, _, addr = value.partition(':')
+            result['impp'].append({'protocol': proto.lower(), 'value': _unescape(addr or value)})
+        elif name == 'CATEGORIES':
+            result['categories'] = [_unescape(c).strip() for c in value.split(',') if c.strip()]
+        elif name == 'BDAY':
+            result['birthday'] = _normalise_date(value)
+        elif name == 'ANNIVERSARY':
+            result['anniversary'] = _normalise_date(value)
+        elif name == 'NOTE':
+            result['notes'] = _unescape(value)
+        elif name == 'PHOTO':
+            result['photo'] = value.strip() or None
+    return result
+
+
+def _normalise_date(s: str):
+    s = s.strip()
+    m = re.match(r'^(\d{4})-?(\d{2})-?(\d{2})$', s[:10])
+    if m:
+        return f'{m.group(1)}-{m.group(2)}-{m.group(3)}'
+    return None
+
+
+# ---------------------------------------------------------------------------
+# Address books
+# ---------------------------------------------------------------------------
 
 @api_bp.route('/addressbooks', methods=['GET'])
 @token_required
@@ -49,7 +288,12 @@ def list_addressbooks():
             address_book_id=b.id, shared_with_id=user.id
         ).first()
         d['permission'] = share.permission if share else 'read'
+        d['owner_color'] = d.get('color')
+        if share and share.color:
+            d['color'] = share.color
         d['owner_name'] = b.owner.username
+        d['owner_full_name'] = b.owner.full_name
+        d['owner_display_name'] = b.owner.display_name
         d['contact_count'] = b.contacts.count()
         result.append(d)
 
@@ -61,13 +305,19 @@ def list_addressbooks():
 def create_addressbook():
     user = request.current_user
     data = request.get_json()
-    name = data.get('name', '').strip()
+    name = (data.get('name') or '').strip()
     if not name:
         return jsonify({'error': 'Name erforderlich'}), 400
 
-    book = AddressBook(owner_id=user.id, name=name, description=data.get('description', ''))
+    book = AddressBook(
+        owner_id=user.id,
+        name=name,
+        color=data.get('color', '#3788d8'),
+        description=data.get('description') or None,
+    )
     db.session.add(book)
     db.session.commit()
+    _notify_addressbook(user.id, book.id, 'created')
     return jsonify(book.to_dict()), 201
 
 
@@ -77,31 +327,66 @@ def update_addressbook(book_id):
     user = request.current_user
     book = db.session.get(AddressBook, book_id)
     if not book or book.owner_id != user.id:
-        return jsonify({'error': 'Nicht gefunden'}), 404
+        return jsonify({'error': 'Nicht gefunden oder keine Berechtigung'}), 404
 
     data = request.get_json()
     if 'name' in data:
         book.name = data['name'].strip()
     if 'description' in data:
-        book.description = data['description']
+        book.description = data['description'] or None
+    if 'color' in data:
+        book.color = data['color']
     db.session.commit()
+    _notify_addressbook(book.owner_id, book.id, 'updated',
+                        shared_with=_book_recipients(book))
     return jsonify(book.to_dict()), 200
 
 
+@api_bp.route('/addressbooks/<int:book_id>/my-color', methods=['PUT'])
+@token_required
+def set_my_addressbook_color(book_id):
+    user = request.current_user
+    book = db.session.get(AddressBook, book_id)
+    if not book:
+        return jsonify({'error': 'Nicht gefunden'}), 404
+    color = ((request.get_json() or {}).get('color') or '').strip()
+
+    if book.owner_id == user.id:
+        if color:
+            book.color = color
+        db.session.commit()
+        return jsonify({'color': book.color}), 200
+
+    share = AddressBookShare.query.filter_by(
+        address_book_id=book_id, shared_with_id=user.id
+    ).first()
+    if not share:
+        return jsonify({'error': 'Kein Zugriff'}), 403
+    share.color = color or None
+    db.session.commit()
+    return jsonify({'color': share.color or book.color}), 200
+
+
 @api_bp.route('/addressbooks/<int:book_id>', methods=['DELETE'])
 @token_required
 def delete_addressbook(book_id):
     user = request.current_user
     book = db.session.get(AddressBook, book_id)
     if not book or book.owner_id != user.id:
-        return jsonify({'error': 'Nicht gefunden'}), 404
+        return jsonify({'error': 'Nicht gefunden oder keine Berechtigung'}), 404
 
+    recipients = _book_recipients(book)
+    owner_id = book.owner_id
+    bid = book.id
     db.session.delete(book)
     db.session.commit()
+    _notify_addressbook(owner_id, bid, 'deleted', shared_with=recipients)
     return jsonify({'message': 'Adressbuch geloescht'}), 200
 
 
-# --- Contacts ---
+# ---------------------------------------------------------------------------
+# Contacts
+# ---------------------------------------------------------------------------
 
 @api_bp.route('/addressbooks/<int:book_id>/contacts', methods=['GET'])
 @token_required
@@ -111,14 +396,174 @@ def list_contacts(book_id):
     if err:
         return err
 
-    search = request.args.get('search', '').strip()
+    search = (request.args.get('q') or '').strip()
-    query = Contact.query.filter_by(address_book_id=book_id)
+    q = Contact.query.filter_by(address_book_id=book_id)
     if search:
-        query = query.filter(Contact.display_name.ilike(f'%{search}%'))
+        like = f'%{search}%'
-    contacts = query.order_by(Contact.display_name).all()
+        q = q.filter(
+            (Contact.display_name.ilike(like)) |
+            (Contact.primary_email.ilike(like)) |
+            (Contact.organization.ilike(like))
+        )
+    contacts = q.order_by(Contact.display_name).all()
     return jsonify([c.to_dict() for c in contacts]), 200
 
 
+@api_bp.route('/addressbooks/<int:book_id>/export', methods=['GET'])
+@token_required
+def export_addressbook(book_id):
+    """Export contacts as a single .vcf, a .zip with one .vcf per contact, or .csv."""
+    user = request.current_user
+    book, err = _get_addressbook_or_err(book_id, user)
+    if err:
+        return err
+    fmt = (request.args.get('format') or 'vcf').lower()
+    contacts = Contact.query.filter_by(address_book_id=book_id).order_by(Contact.display_name).all()
+    safe_name = re.sub(r'[^A-Za-z0-9._-]+', '_', book.name or 'kontakte') or 'kontakte'
+
+    if fmt == 'vcf':
+        body = '\r\n'.join((c.vcard_data or _build_vcard(c)).strip() for c in contacts) + '\r\n'
+        return Response(
+            body, mimetype='text/vcard; charset=utf-8',
+            headers={'Content-Disposition': f'attachment; filename="{safe_name}.vcf"'},
+        )
+    if fmt == 'vcf-zip':
+        buf = io.BytesIO()
+        with zipfile.ZipFile(buf, 'w', zipfile.ZIP_DEFLATED) as zf:
+            seen = {}
+            for c in contacts:
+                base = re.sub(r'[^A-Za-z0-9._-]+', '_', c.display_name or c.uid) or c.uid
+                seen[base] = seen.get(base, 0) + 1
+                fname = f"{base}.vcf" if seen[base] == 1 else f"{base}_{seen[base]}.vcf"
+                zf.writestr(fname, (c.vcard_data or _build_vcard(c)).strip() + '\r\n')
+        buf.seek(0)
+        return Response(
+            buf.read(), mimetype='application/zip',
+            headers={'Content-Disposition': f'attachment; filename="{safe_name}.zip"'},
+        )
+    if fmt == 'csv':
+        out = io.StringIO()
+        cols = ['display_name', 'prefix', 'first_name', 'middle_name', 'last_name', 'suffix',
+                'nickname', 'organization', 'department', 'job_title',
+                'primary_email', 'primary_phone', 'birthday', 'anniversary',
+                'emails', 'phones', 'addresses', 'websites', 'categories', 'notes']
+        w = csv.writer(out, delimiter=';', quoting=csv.QUOTE_ALL)
+        w.writerow(cols)
+        for c in contacts:
+            d = c.to_dict()
+            row = []
+            for col in cols:
+                v = d.get(col, '')
+                if isinstance(v, list):
+                    if v and isinstance(v[0], dict):
+                        v = '; '.join(
+                            (x.get('value') or x.get('street') or '') +
+                            (f" ({x.get('type')})" if x.get('type') else '')
+                            for x in v if isinstance(x, dict)
+                        )
+                    else:
+                        v = ', '.join(str(x) for x in v)
+                row.append('' if v is None else str(v))
+            w.writerow(row)
+        return Response(
+            '\ufeff' + out.getvalue(), mimetype='text/csv; charset=utf-8',
+            headers={'Content-Disposition': f'attachment; filename="{safe_name}.csv"'},
+        )
+    return jsonify({'error': 'Unbekanntes Format'}), 400
+
+
+@api_bp.route('/addressbooks/<int:book_id>/import', methods=['POST'])
+@token_required
+def import_addressbook(book_id):
+    """Import vCard (.vcf, single oder mehrere im File) oder CSV."""
+    user = request.current_user
+    book, err = _get_addressbook_or_err(book_id, user, need_write=True)
+    if err:
+        return err
+    file = request.files.get('file')
+    if not file:
+        return jsonify({'error': 'Keine Datei'}), 400
+    raw = file.read()
+    name = (file.filename or '').lower()
+    try:
+        text = raw.decode('utf-8-sig')
+    except UnicodeDecodeError:
+        text = raw.decode('latin-1', errors='replace')
+
+    imported = 0
+    skipped = 0
+
+    def _add_from_parsed(parsed: dict, raw_text: str | None = None) -> bool:
+        nonlocal imported, skipped
+        if not parsed.get('display_name') and not parsed.get('first_name') \
+                and not parsed.get('last_name') and not parsed.get('organization'):
+            skipped += 1
+            return False
+        uid = parsed.get('uid') or str(uuid.uuid4())
+        existing = Contact.query.filter_by(address_book_id=book_id, uid=uid).first()
+        contact = existing or Contact(address_book_id=book_id, uid=uid, vcard_data='')
+        _apply_fields_to_contact(contact, parsed)
+        contact.vcard_data = (raw_text or '').strip() or _build_vcard(contact)
+        contact.updated_at = datetime.now(timezone.utc)
+        if not existing:
+            db.session.add(contact)
+        imported += 1
+        return True
+
+    if name.endswith('.csv') or (b',' in raw[:200] and b'BEGIN:VCARD' not in raw[:200]):
+        # CSV import
+        reader = csv.DictReader(io.StringIO(text), delimiter=';')
+        if not reader.fieldnames or len(reader.fieldnames) < 2:
+            # try comma
+            reader = csv.DictReader(io.StringIO(text), delimiter=',')
+        for row in reader:
+            row = {k.strip().lower(): (v or '').strip() for k, v in row.items() if k}
+            parsed = {
+                'display_name': row.get('display_name') or row.get('name')
+                                or row.get('vollname') or row.get('full name'),
+                'first_name': row.get('first_name') or row.get('vorname'),
+                'last_name': row.get('last_name') or row.get('nachname'),
+                'middle_name': row.get('middle_name'),
+                'prefix': row.get('prefix') or row.get('anrede'),
+                'suffix': row.get('suffix'),
+                'nickname': row.get('nickname') or row.get('spitzname'),
+                'organization': row.get('organization') or row.get('firma') or row.get('company'),
+                'department': row.get('department') or row.get('abteilung'),
+                'job_title': row.get('job_title') or row.get('position') or row.get('title'),
+                'birthday': row.get('birthday') or row.get('geburtstag'),
+                'notes': row.get('notes') or row.get('notizen'),
+                'emails': [], 'phones': [], 'addresses': [], 'websites': [], 'categories': [],
+            }
+            email = row.get('primary_email') or row.get('email') or row.get('e-mail')
+            if email:
+                parsed['emails'].append({'type': 'home', 'value': email})
+            phone = row.get('primary_phone') or row.get('phone') or row.get('telefon') or row.get('mobil')
+            if phone:
+                parsed['phones'].append({'type': 'cell', 'value': phone})
+            cats = row.get('categories') or row.get('kategorien')
+            if cats:
+                parsed['categories'] = [c.strip() for c in cats.split(',') if c.strip()]
+            _add_from_parsed(parsed)
+    else:
+        # vCard - eine oder mehrere im File
+        parts = re.findall(r'BEGIN:VCARD.*?END:VCARD', text, flags=re.DOTALL | re.IGNORECASE)
+        if not parts:
+            return jsonify({'error': 'Keine VCARD-Daten gefunden'}), 400
+        for vcf in parts:
+            try:
+                parsed = parse_vcard(vcf)
+            except Exception:
+                skipped += 1
+                continue
+            _add_from_parsed(parsed, raw_text=vcf)
+
+    db.session.commit()
+    if imported:
+        _notify_addressbook(book.owner_id, book.id, 'contact',
+                            shared_with=_book_recipients(book))
+    return jsonify({'imported': imported, 'skipped': skipped}), 200
+
+
 @api_bp.route('/addressbooks/<int:book_id>/contacts', methods=['POST'])
 @token_required
 def create_contact(book_id):
@@ -127,29 +572,16 @@ def create_contact(book_id):
     if err:
         return err
 
-    data = request.get_json()
+    data = request.get_json() or {}
-    display_name = data.get('display_name', '').strip()
+    contact = Contact(address_book_id=book_id, uid=str(uuid.uuid4()), vcard_data='')
-    if not display_name:
+    _apply_fields_to_contact(contact, data)
-        return jsonify({'error': 'Name erforderlich'}), 400
+    if not contact.display_name:
-
+        return jsonify({'error': 'Name oder Firma erforderlich'}), 400
-    contact_uid = str(uuid.uuid4())
+    contact.vcard_data = _build_vcard(contact)
-    email = data.get('email', '')
-    phone = data.get('phone', '')
-    org = data.get('organization', '')
-    notes = data.get('notes', '')
-
-    vcard = _build_vcard(contact_uid, display_name, email, phone, org, notes)
-
-    contact = Contact(
-        address_book_id=book_id,
-        uid=contact_uid,
-        vcard_data=vcard,
-        display_name=display_name,
-        email=email or None,
-        phone=phone or None,
-    )
     db.session.add(contact)
     db.session.commit()
+    _notify_addressbook(book.owner_id, book.id, 'contact',
+                        shared_with=_book_recipients(book))
     return jsonify(contact.to_dict()), 201
 
 
@@ -160,11 +592,9 @@ def get_contact(contact_id):
     contact = db.session.get(Contact, contact_id)
     if not contact:
         return jsonify({'error': 'Kontakt nicht gefunden'}), 404
-
     book, err = _get_addressbook_or_err(contact.address_book_id, user)
     if err:
         return err
-
     result = contact.to_dict()
     result['vcard_data'] = contact.vcard_data
     return jsonify(result), 200
@@ -177,29 +607,17 @@ def update_contact(contact_id):
     contact = db.session.get(Contact, contact_id)
     if not contact:
         return jsonify({'error': 'Kontakt nicht gefunden'}), 404
-
     book, err = _get_addressbook_or_err(contact.address_book_id, user, need_write=True)
     if err:
         return err
 
-    data = request.get_json()
+    data = request.get_json() or {}
-    if 'display_name' in data:
+    _apply_fields_to_contact(contact, data)
-        contact.display_name = data['display_name'].strip()
+    contact.vcard_data = _build_vcard(contact)
-    if 'email' in data:
-        contact.email = data['email'] or None
-    if 'phone' in data:
-        contact.phone = data['phone'] or None
-
-    contact.vcard_data = _build_vcard(
-        contact.uid,
-        contact.display_name,
-        data.get('email', contact.email or ''),
-        data.get('phone', contact.phone or ''),
-        data.get('organization', ''),
-        data.get('notes', ''),
-    )
     contact.updated_at = datetime.now(timezone.utc)
     db.session.commit()
+    _notify_addressbook(book.owner_id, book.id, 'contact',
+                        shared_with=_book_recipients(book))
     return jsonify(contact.to_dict()), 200
 
 
@@ -210,17 +628,19 @@ def delete_contact(contact_id):
     contact = db.session.get(Contact, contact_id)
     if not contact:
         return jsonify({'error': 'Kontakt nicht gefunden'}), 404
-
     book, err = _get_addressbook_or_err(contact.address_book_id, user, need_write=True)
     if err:
         return err
-
     db.session.delete(contact)
     db.session.commit()
+    _notify_addressbook(book.owner_id, book.id, 'contact',
+                        shared_with=_book_recipients(book))
     return jsonify({'message': 'Kontakt geloescht'}), 200
 
 
-# --- Sharing ---
+# ---------------------------------------------------------------------------
+# Sharing
+# ---------------------------------------------------------------------------
 
 @api_bp.route('/addressbooks/<int:book_id>/share', methods=['POST'])
 @token_required
@@ -230,10 +650,9 @@ def share_addressbook(book_id):
     if not book or book.owner_id != user.id:
         return jsonify({'error': 'Nur der Eigentuemer kann teilen'}), 403
 
-    data = request.get_json()
+    data = request.get_json() or {}
-    username = data.get('username', '').strip()
+    username = (data.get('username') or '').strip()
     permission = data.get('permission', 'read')
-
     if permission not in ('read', 'readwrite'):
         return jsonify({'error': 'Ungueltige Berechtigung'}), 400
 
@@ -246,7 +665,6 @@ def share_addressbook(book_id):
     existing = AddressBookShare.query.filter_by(
         address_book_id=book_id, shared_with_id=target.id
     ).first()
-    is_new = not existing
     if existing:
         existing.permission = permission
     else:
@@ -254,16 +672,9 @@ def share_addressbook(book_id):
             address_book_id=book_id, shared_with_id=target.id, permission=permission
         )
         db.session.add(share)
-
     db.session.commit()
-
+    _notify_addressbook(book.owner_id, book.id, 'share',
-    if is_new:
+                        shared_with=[target.id, *_book_recipients(book)])
-        try:
-            from app.services.system_mail import notify_contacts_shared
-            notify_contacts_shared(book.name, user.username, target, permission)
-        except Exception:
-            pass
-
     return jsonify({'message': f'Adressbuch mit {username} geteilt'}), 200
 
 
@@ -274,7 +685,6 @@ def list_addressbook_shares(book_id):
     book = db.session.get(AddressBook, book_id)
     if not book or book.owner_id != user.id:
         return jsonify({'error': 'Nicht gefunden'}), 404
-
     shares = AddressBookShare.query.filter_by(address_book_id=book_id).all()
     return jsonify([{
         'id': s.id,
@@ -291,17 +701,20 @@ def remove_addressbook_share(book_id, share_id):
     book = db.session.get(AddressBook, book_id)
     if not book or book.owner_id != user.id:
         return jsonify({'error': 'Nicht gefunden'}), 404
-
     share = db.session.get(AddressBookShare, share_id)
     if not share or share.address_book_id != book_id:
         return jsonify({'error': 'Freigabe nicht gefunden'}), 404
-
+    target_id = share.shared_with_id
     db.session.delete(share)
     db.session.commit()
+    _notify_addressbook(book.owner_id, book.id, 'share',
+                        shared_with=[target_id, *_book_recipients(book)])
     return jsonify({'message': 'Freigabe entfernt'}), 200
 
 
-# --- Import/Export ---
+# ---------------------------------------------------------------------------
+# vCard export (all contacts of a book)
+# ---------------------------------------------------------------------------
 
 @api_bp.route('/addressbooks/<int:book_id>/export', methods=['GET'])
 @token_required
@@ -310,40 +723,9 @@ def export_contacts(book_id):
     book, err = _get_addressbook_or_err(book_id, user)
     if err:
         return err
-
+    parts = [c.vcard_data for c in book.contacts]
-    contacts = Contact.query.filter_by(address_book_id=book_id).all()
-    vcards = '\r\n'.join(c.vcard_data for c in contacts)
-
-    from flask import Response
     return Response(
-        vcards,
+        '\r\n'.join(parts),
-        mimetype='text/vcard',
+        mimetype='text/vcard; charset=utf-8',
         headers={'Content-Disposition': f'attachment; filename="{book.name}.vcf"'},
     )
-
-
-# --- Helpers ---
-
-def _build_vcard(uid, display_name, email='', phone='', org='', notes=''):
-    parts = display_name.split(' ', 1)
-    first = parts[0]
-    last = parts[1] if len(parts) > 1 else ''
-
-    lines = [
-        'BEGIN:VCARD',
-        'VERSION:3.0',
-        f'UID:{uid}',
-        f'FN:{display_name}',
-        f'N:{last};{first};;;',
-    ]
-    if email:
-        lines.append(f'EMAIL:{email}')
-    if phone:
-        lines.append(f'TEL:{phone}')
-    if org:
-        lines.append(f'ORG:{org}')
-    if notes:
-        lines.append(f'NOTE:{notes}')
-    lines.append(f'REV:{datetime.now(timezone.utc).strftime("%Y%m%dT%H%M%SZ")}')
-    lines.append('END:VCARD')
-    return '\r\n'.join(lines)

backend/app/api/files.py

@@ -15,6 +15,45 @@ from app.api import api_bp
 from app.api.auth import token_required
 from app.extensions import db, bcrypt
 from app.models.file import File, FilePermission, ShareLink
+from app.models.file_lock import FileLock
+from app.services.events import broadcaster, notify_file_change
+
+
+def _share_recipients(file_obj):
+    """Return a list of user ids (besides the owner) that should see changes
+    to this file because they have a direct share permission on it or on
+    any of its ancestor folders."""
+    ids = set()
+    cur = file_obj
+    while cur is not None:
+        for p in FilePermission.query.filter_by(file_id=cur.id).all():
+            ids.add(p.user_id)
+        cur = cur.parent
+    ids.discard(file_obj.owner_id)
+    return list(ids)
+
+
+def _effective_permission(file_obj, user):
+    """Returns (permission_level, can_reshare) for the given user on this file,
+    walking up the folder tree. Owner gets ('admin', True). Returns
+    (None, False) if no access."""
+    if file_obj.owner_id == user.id:
+        return ('admin', True)
+    levels = {'read': 0, 'write': 1, 'admin': 2}
+    best_level = -1
+    best_perm = None
+    best_reshare = False
+    cur = file_obj
+    while cur is not None:
+        perm = FilePermission.query.filter_by(file_id=cur.id, user_id=user.id).first()
+        if perm:
+            lvl = levels.get(perm.permission, -1)
+            if lvl > best_level:
+                best_level = lvl
+                best_perm = perm.permission
+                best_reshare = perm.can_reshare
+        cur = cur.parent
+    return (best_perm, best_reshare)
 
 
 def _user_upload_dir(user_id):
@@ -25,16 +64,22 @@ def _user_upload_dir(user_id):
 
 
 def _check_file_access(file_obj, user, permission='read'):
-    """Check if user has access to file. Owner always has full access."""
+    """Check if user has access to file. Owner always has full access.
+    A permission on an ancestor folder also grants access to all descendants."""
     if file_obj.owner_id == user.id:
         return True
-    perm = FilePermission.query.filter_by(
-        file_id=file_obj.id, user_id=user.id
-    ).first()
-    if not perm:
-        return False
     perm_levels = {'read': 0, 'write': 1, 'admin': 2}
-    return perm_levels.get(perm.permission, -1) >= perm_levels.get(permission, 0)
+    needed = perm_levels.get(permission, 0)
+    # Walk up the tree looking for a permission on this file or any ancestor
+    cur = file_obj
+    while cur is not None:
+        perm = FilePermission.query.filter_by(
+            file_id=cur.id, user_id=user.id
+        ).first()
+        if perm and perm_levels.get(perm.permission, -1) >= needed:
+            return True
+        cur = cur.parent
+    return False
 
 
 def _get_file_or_403(file_id, user, permission='read'):
@@ -62,9 +107,25 @@ def list_files():
     user = request.current_user
     parent_id = request.args.get('parent_id', None, type=int)
 
-    # Own files in this folder (exclude trashed)
+    # When browsing into a folder, verify access first. If the folder is
-    query = File.query.filter_by(owner_id=user.id, parent_id=parent_id, is_trashed=False)
+    # shared with us (directly or via an ancestor), list ALL its children
-    files = query.order_by(File.is_folder.desc(), File.name).all()
+    # - not just ones owned by us.
+    if parent_id is not None:
+        parent_folder, perr = _get_file_or_403(parent_id, user, 'read')
+        if perr:
+            return perr
+        if parent_folder.owner_id == user.id:
+            files = File.query.filter_by(
+                owner_id=user.id, parent_id=parent_id, is_trashed=False
+            ).order_by(File.is_folder.desc(), File.name).all()
+        else:
+            files = File.query.filter_by(
+                parent_id=parent_id, is_trashed=False
+            ).order_by(File.is_folder.desc(), File.name).all()
+    else:
+        files = File.query.filter_by(
+            owner_id=user.id, parent_id=None, is_trashed=False
+        ).order_by(File.is_folder.desc(), File.name).all()
 
     # Shared files at root level
     shared = []
@@ -74,7 +135,7 @@ def list_files():
         if shared_file_ids:
             shared = File.query.filter(
                 File.id.in_(shared_file_ids),
-                File.parent_id.is_(None)
+                File.is_trashed == False  # noqa: E712
             ).order_by(File.is_folder.desc(), File.name).all()
 
     result = []
@@ -82,10 +143,21 @@ def list_files():
         d = f.to_dict()
         d['has_shares'] = ShareLink.query.filter_by(file_id=f.id).count() > 0
         d['has_permissions'] = FilePermission.query.filter_by(file_id=f.id).count() > 0
+        my_perm, my_reshare = _effective_permission(f, user)
+        d['my_permission'] = my_perm
+        d['my_can_reshare'] = bool(my_reshare)
+        lock = FileLock.get_lock(f.id)
+        if lock:
+            d['locked'] = True
+            d['locked_by'] = lock.user.username
+            d['locked_at'] = lock.locked_at.isoformat()
         result.append(d)
     for f in shared:
         d = f.to_dict()
         d['shared'] = True
+        my_perm, my_reshare = _effective_permission(f, user)
+        d['my_permission'] = my_perm
+        d['my_can_reshare'] = bool(my_reshare)
         result.append(d)
 
     # Build breadcrumb
@@ -131,6 +203,8 @@ def create_folder():
     )
     db.session.add(folder)
     db.session.commit()
+    notify_file_change(folder.owner_id, folder.id, 'created',
+                       shared_with=_share_recipients(folder))
     return jsonify(folder.to_dict()), 201
 
 
@@ -222,6 +296,8 @@ def upload_file():
         existing.checksum = checksum
         existing.updated_at = datetime.now(timezone.utc)
         db.session.commit()
+        notify_file_change(existing.owner_id, existing.id, 'updated',
+                           shared_with=_share_recipients(existing))
         return jsonify(existing.to_dict()), 200
 
     file_obj = File(
@@ -236,6 +312,8 @@ def upload_file():
     )
     db.session.add(file_obj)
     db.session.commit()
+    notify_file_change(file_obj.owner_id, file_obj.id, 'created',
+                       shared_with=_share_recipients(file_obj))
     return jsonify(file_obj.to_dict()), 201
 
 
@@ -256,8 +334,11 @@ def download_file(file_id):
     if not filepath.exists():
         return jsonify({'error': 'Datei auf Datentraeger nicht gefunden'}), 404
 
-    return send_file(str(filepath), mimetype=f.mime_type, as_attachment=True,
+    # inline=1 renders the file in-browser (used by PDF/image previews).
-                     download_name=f.name)
+    # Default is attachment so normal download buttons still save to disk.
+    inline = request.args.get('inline', '0') == '1'
+    return send_file(str(filepath), mimetype=f.mime_type,
+                     as_attachment=not inline, download_name=f.name)
 
 
 def _download_folder_as_zip(folder):
@@ -300,6 +381,11 @@ def update_file(file_id):
     if err:
         return err
 
+    # Lock-Check: fremder Lock blockiert Aenderungen (admin kann durch)
+    lock = FileLock.get_lock(file_id)
+    if lock and lock.locked_by != user.id and user.role != 'admin':
+        return jsonify({'error': f'Datei ist von {lock.user.username} ausgecheckt'}), 423
+
     data = request.get_json()
     if 'name' in data:
         name = data['name'].strip()
@@ -325,6 +411,8 @@ def update_file(file_id):
 
     f.updated_at = datetime.now(timezone.utc)
     db.session.commit()
+    notify_file_change(f.owner_id, f.id, 'updated',
+                       shared_with=_share_recipients(f))
     return jsonify(f.to_dict()), 200
 
 
@@ -340,9 +428,18 @@ def delete_file(file_id):
         if not f or f.owner_id != user.id:
             return jsonify({'error': 'Zugriff verweigert'}), 403
 
+    # Lock-Check
+    lock = FileLock.get_lock(file_id)
+    if lock and lock.locked_by != user.id and user.role != 'admin':
+        return jsonify({'error': f'Datei ist von {lock.user.username} ausgecheckt'}), 423
+
+    # Capture recipients BEFORE we detach the file from its parent tree
+    recipients = _share_recipients(f)
+    owner_id = f.owner_id
     # Soft-delete: move to trash
     _trash_recursive(f)
     db.session.commit()
+    notify_file_change(owner_id, f.id, 'deleted', shared_with=recipients)
     return jsonify({'message': 'In Papierkorb verschoben'}), 200
 
 
@@ -475,12 +572,21 @@ def empty_trash():
 @token_required
 def get_permissions(file_id):
     user = request.current_user
-    f, err = _get_file_or_403(file_id, user, 'admin')
+    f = db.session.get(File, file_id)
-    if err:
+    if not f:
-        if not (f := db.session.get(File, file_id)) or f.owner_id != user.id:
+        return jsonify({'error': 'Datei nicht gefunden'}), 404
-            return jsonify({'error': 'Zugriff verweigert'}), 403
+
+    is_owner = (f.owner_id == user.id)
+    my_perm, my_reshare = _effective_permission(f, user)
+    if not is_owner and not my_reshare:
+        return jsonify({'error': 'Zugriff verweigert'}), 403
+
+    # Owners see everyone; re-sharers only see perms they granted themselves.
+    if is_owner:
+        perms = FilePermission.query.filter_by(file_id=file_id).all()
+    else:
+        perms = FilePermission.query.filter_by(file_id=file_id, granted_by=user.id).all()
 
-    perms = FilePermission.query.filter_by(file_id=file_id).all()
     from app.models.user import User
     result = []
     for p in perms:
@@ -490,6 +596,8 @@ def get_permissions(file_id):
             'user_id': p.user_id,
             'username': u.username if u else None,
             'permission': p.permission,
+            'can_reshare': bool(p.can_reshare),
+            'granted_by': p.granted_by,
         })
     return jsonify(result), 200
 
@@ -499,33 +607,69 @@ def get_permissions(file_id):
 def set_permission(file_id):
     user = request.current_user
     f = db.session.get(File, file_id)
-    if not f or f.owner_id != user.id:
+    if not f:
-        return jsonify({'error': 'Nur der Eigentuemer kann Berechtigungen setzen'}), 403
+        return jsonify({'error': 'Datei nicht gefunden'}), 404
+
+    is_owner = (f.owner_id == user.id)
+    my_perm, my_reshare = _effective_permission(f, user)
+    if not is_owner and not my_reshare:
+        return jsonify({'error': 'Keine Berechtigung zum Weiterteilen'}), 403
 
     data = request.get_json()
     target_user_id = data.get('user_id')
     permission = data.get('permission', 'read')
+    can_reshare_req = bool(data.get('can_reshare', False))
 
     if permission not in ('read', 'write', 'admin'):
         return jsonify({'error': 'Ungueltige Berechtigung'}), 400
 
+    # Re-sharers can't hand out more than they have themselves.
+    levels = {'read': 0, 'write': 1, 'admin': 2}
+    if not is_owner:
+        max_allowed = levels.get(my_perm, -1)
+        if levels.get(permission, -1) > max_allowed:
+            return jsonify({
+                'error': f'Du kannst hoechstens "{my_perm}" weiterverteilen'
+            }), 403
+        if permission == 'admin':
+            return jsonify({'error': 'Admin-Recht kann nur der Eigentuemer vergeben'}), 403
+
     from app.models.user import User
     target = db.session.get(User, target_user_id)
     if not target:
         return jsonify({'error': 'Benutzer nicht gefunden'}), 404
+    if target.id == f.owner_id:
+        return jsonify({'error': 'Eigentuemer hat bereits Vollzugriff'}), 400
 
     existing = FilePermission.query.filter_by(
         file_id=file_id, user_id=target_user_id
     ).first()
     is_new = not existing
     if existing:
+        # Re-sharers may only modify perms they themselves granted
+        if not is_owner and existing.granted_by != user.id:
+            return jsonify({'error': 'Diese Freigabe wurde von jemand anderem erstellt'}), 403
         existing.permission = permission
+        existing.can_reshare = can_reshare_req
+        if is_new or existing.granted_by is None:
+            existing.granted_by = user.id
     else:
-        perm = FilePermission(file_id=file_id, user_id=target_user_id, permission=permission)
+        perm = FilePermission(
+            file_id=file_id,
+            user_id=target_user_id,
+            permission=permission,
+            can_reshare=can_reshare_req,
+            granted_by=user.id,
+        )
         db.session.add(perm)
 
     db.session.commit()
 
+    # SSE: notify target user (they just got/updated access) + owner + other
+    # share recipients so everyone's file list refreshes.
+    notify_file_change(f.owner_id, f.id, 'permission',
+                       shared_with=[target.id, *_share_recipients(f)])
+
     # Notify user via email
     if is_new:
         try:
@@ -542,15 +686,24 @@ def set_permission(file_id):
 def remove_permission(file_id, perm_id):
     user = request.current_user
     f = db.session.get(File, file_id)
-    if not f or f.owner_id != user.id:
+    if not f:
-        return jsonify({'error': 'Nur der Eigentuemer kann Berechtigungen entfernen'}), 403
+        return jsonify({'error': 'Datei nicht gefunden'}), 404
 
     perm = db.session.get(FilePermission, perm_id)
     if not perm or perm.file_id != file_id:
         return jsonify({'error': 'Berechtigung nicht gefunden'}), 404
 
+    is_owner = (f.owner_id == user.id)
+    if not is_owner and perm.granted_by != user.id:
+        return jsonify({'error': 'Du kannst nur selbst erstellte Freigaben entfernen'}), 403
+
+    target_user_id = perm.user_id
     db.session.delete(perm)
     db.session.commit()
+
+    notify_file_change(f.owner_id, f.id, 'permission',
+                       shared_with=[target_user_id, *_share_recipients(f)])
+
     return jsonify({'message': 'Berechtigung entfernt'}), 200
 
 
@@ -560,9 +713,14 @@ def remove_permission(file_id, perm_id):
 @token_required
 def create_share_link(file_id):
     user = request.current_user
-    f, err = _get_file_or_403(file_id, user, 'read')
+    f = db.session.get(File, file_id)
-    if err:
+    if not f:
-        return err
+        return jsonify({'error': 'Datei nicht gefunden'}), 404
+
+    is_owner = (f.owner_id == user.id)
+    my_perm, my_reshare = _effective_permission(f, user)
+    if not is_owner and not my_reshare:
+        return jsonify({'error': 'Keine Berechtigung zum Weiterteilen'}), 403
 
     data = request.get_json() or {}
     password = data.get('password')
@@ -573,6 +731,18 @@ def create_share_link(file_id):
     if permission not in ('read', 'write', 'upload_only'):
         return jsonify({'error': 'Berechtigung muss "read", "write" oder "upload_only" sein'}), 400
 
+    # Re-sharers can only hand out what they have themselves.
+    if not is_owner:
+        levels = {'read': 0, 'write': 1}
+        max_allowed = levels.get(my_perm, -1)
+        requested = levels.get(permission, 99)
+        if requested > max_allowed:
+            return jsonify({
+                'error': f'Du hast selbst nur "{my_perm}" - kannst nicht schreibend weiterteilen'
+            }), 403
+        if permission == 'upload_only' and my_perm not in ('write', 'admin'):
+            return jsonify({'error': 'Upload-Links nur mit Schreibrecht moeglich'}), 403
+
     token = secrets.token_urlsafe(32)
     password_hash = None
     if password:
@@ -975,33 +1145,205 @@ def delete_share_link(token):
     return jsonify({'message': 'Link geloescht'}), 200
 
 
+# --- File Locking ---
+
+@api_bp.route('/files/<int:file_id>/lock', methods=['POST'])
+@token_required
+def lock_file(file_id):
+    """Lock a file (check out). Prevents others from opening/editing."""
+    user = request.current_user
+    f = db.session.get(File, file_id)
+    if not f:
+        return jsonify({'error': 'Datei nicht gefunden'}), 404
+
+    # Check existing lock
+    existing = FileLock.get_lock(file_id)
+    if existing:
+        if existing.locked_by == user.id:
+            # Already locked by this user - refresh heartbeat
+            existing.heartbeat_at = datetime.now(timezone.utc)
+            db.session.commit()
+            return jsonify(existing.to_dict()), 200
+        return jsonify({
+            'error': f'Datei wird von {existing.user.username} bearbeitet',
+            'locked_by': existing.user.username,
+            'locked_at': existing.locked_at.isoformat(),
+        }), 423  # 423 Locked
+
+    data = request.get_json(silent=True) or {}
+    lock = FileLock(
+        file_id=file_id,
+        locked_by=user.id,
+        client_info=data.get('client_info', ''),
+    )
+    db.session.add(lock)
+    db.session.commit()
+    notify_file_change(f.owner_id, f.id, 'locked',
+                       shared_with=_share_recipients(f))
+    return jsonify(lock.to_dict()), 200
+
+
+@api_bp.route('/files/<int:file_id>/unlock', methods=['POST'])
+@token_required
+def unlock_file(file_id):
+    """Unlock a file (check in)."""
+    user = request.current_user
+    lock = FileLock.get_lock(file_id)
+    if not lock:
+        return jsonify({'message': 'Datei war nicht gesperrt'}), 200
+
+    if lock.locked_by != user.id and user.role != 'admin':
+        return jsonify({'error': 'Nur der Sperrer oder ein Admin kann entsperren'}), 403
+
+    db.session.delete(lock)
+    db.session.commit()
+    f = db.session.get(File, file_id)
+    if f:
+        notify_file_change(f.owner_id, f.id, 'unlocked',
+                           shared_with=_share_recipients(f))
+    return jsonify({'message': 'Datei entsperrt'}), 200
+
+
+@api_bp.route('/files/<int:file_id>/heartbeat', methods=['POST'])
+@token_required
+def heartbeat_file(file_id):
+    """Heartbeat - signal that the file is still being edited."""
+    user = request.current_user
+    lock = FileLock.get_lock(file_id)
+    if not lock:
+        return jsonify({'error': 'Keine Sperre vorhanden'}), 404
+
+    if lock.locked_by != user.id:
+        return jsonify({'error': 'Sperre gehoert einem anderen Benutzer'}), 403
+
+    lock.heartbeat_at = datetime.now(timezone.utc)
+    db.session.commit()
+    return jsonify({'message': 'Heartbeat aktualisiert'}), 200
+
+
+@api_bp.route('/files/<int:file_id>/lock-status', methods=['GET'])
+@token_required
+def lock_status(file_id):
+    """Check if a file is locked."""
+    lock = FileLock.get_lock(file_id)
+    if not lock:
+        return jsonify({'locked': False}), 200
+
+    return jsonify({
+        'locked': True,
+        'locked_by': lock.user.username,
+        'locked_by_id': lock.locked_by,
+        'locked_at': lock.locked_at.isoformat(),
+        'client_info': lock.client_info,
+    }), 200
+
+
+@api_bp.route('/files/locks', methods=['GET'])
+@token_required
+def list_locks():
+    """List all active locks (for admin overview or sync clients)."""
+    # Cleanup expired first
+    FileLock.cleanup_expired()
+
+    locks = FileLock.query.all()
+    return jsonify([l.to_dict() for l in locks]), 200
+
+
 # --- Sync API ---
 
 @api_bp.route('/sync/tree', methods=['GET'])
 @token_required
 def sync_tree():
-    """Returns complete file tree with checksums for sync clients."""
+    """Returns complete file tree with checksums for sync clients.
+
+    Includes both files owned by the user (under 'tree') and files
+    shared WITH the user (as a virtual 'Geteilt mit mir' folder under
+    'shared'). The client merges both.
+    """
     user = request.current_user
 
+    def _entry(f):
+        entry = {
+            'id': f.id,
+            'name': f.name,
+            'is_folder': f.is_folder,
+            'size': f.size,
+            'checksum': f.checksum,
+            'updated_at': f.updated_at.isoformat() if f.updated_at else None,
+            'modified_at': f.updated_at.isoformat() if f.updated_at else None,
+        }
+        lock = FileLock.get_lock(f.id)
+        if lock:
+            entry['locked'] = True
+            entry['locked_by'] = lock.user.username
+        return entry
+
     def _build_tree(parent_id):
-        files = File.query.filter_by(owner_id=user.id, parent_id=parent_id)\
+        files = File.query.filter_by(owner_id=user.id, parent_id=parent_id, is_trashed=False)\
             .order_by(File.is_folder.desc(), File.name).all()
         result = []
         for f in files:
-            entry = {
+            e = _entry(f)
-                'id': f.id,
-                'name': f.name,
-                'is_folder': f.is_folder,
-                'size': f.size,
-                'checksum': f.checksum,
-                'updated_at': f.updated_at.isoformat() if f.updated_at else None,
-            }
             if f.is_folder:
-                entry['children'] = _build_tree(f.id)
+                e['children'] = _build_tree(f.id)
-            result.append(entry)
+            result.append(e)
         return result
 
-    return jsonify({'tree': _build_tree(None)}), 200
+    def _build_shared_children(parent_id):
+        files = File.query.filter_by(parent_id=parent_id, is_trashed=False)\
+            .order_by(File.is_folder.desc(), File.name).all()
+        out = []
+        for f in files:
+            e = _entry(f)
+            if f.is_folder:
+                e['children'] = _build_shared_children(f.id)
+            out.append(e)
+        return out
+
+    shared_perms = FilePermission.query.filter_by(user_id=user.id).all()
+    shared_roots = []
+    seen = set()
+    for perm in shared_perms:
+        f = perm.file
+        if not f or f.is_trashed or f.id in seen:
+            continue
+        seen.add(f.id)
+        # Nur "Top-Level"-Shares: wenn der Eltern-Ordner NICHT auch geteilt
+        # ist, ist dieses Item die Wurzel des Shares beim Empfaenger.
+        parent_shared = any(
+            p.file_id == f.parent_id for p in shared_perms
+        ) if f.parent_id else False
+        if parent_shared:
+            continue
+        e = _entry(f)
+        owner = f.owner.display_name if hasattr(f, 'owner') and f.owner else None
+        if owner:
+            e['name'] = f'{f.name} (von {owner})'
+        if f.is_folder:
+            e['children'] = _build_shared_children(f.id)
+        shared_roots.append(e)
+
+    return jsonify({
+        'tree': _build_tree(None),
+        'shared': shared_roots,
+    }), 200
+
+
+@api_bp.route('/sync/events', methods=['GET'])
+@token_required
+def sync_events():
+    """Server-Sent Events stream: real-time file change notifications."""
+    user = request.current_user
+    user_id = user.id
+
+    def event_stream():
+        yield from broadcaster.stream(user_id)
+
+    resp = Response(event_stream(), mimetype='text/event-stream')
+    resp.headers['Cache-Control'] = 'no-cache'
+    resp.headers['X-Accel-Buffering'] = 'no'  # disable nginx buffering
+    resp.headers['Connection'] = 'keep-alive'
+    return resp
 
 
 @api_bp.route('/sync/changes', methods=['GET'])

backend/app/api/office.py

@@ -1,21 +1,29 @@
 import io
 import os
 import hashlib
-from datetime import datetime, timezone
+from datetime import datetime, timezone, timedelta
 from pathlib import Path
 
 from flask import request, jsonify, current_app, send_file
 
 from app.api import api_bp
 from app.api.auth import token_required
-from app.api.files import _get_file_or_403
+from app.api.files import _get_file_or_403, _share_recipients
 from app.extensions import db
 from app.models.settings import AppSettings
+from app.services.events import notify_file_change
 
 
 @api_bp.route('/files/<int:file_id>/preview', methods=['GET'])
 @token_required
 def preview_file(file_id):
+    from flask import after_this_request
+    @after_this_request
+    def add_no_cache(response):
+        response.headers['Cache-Control'] = 'no-cache, no-store, must-revalidate'
+        response.headers['Pragma'] = 'no-cache'
+        return response
+
     user = request.current_user
     f, err = _get_file_or_403(file_id, user, 'read')
     if err:
@@ -212,6 +220,8 @@ def save_file(file_id):
         f.updated_at = datetime.now(timezone.utc)
         db.session.commit()
 
+        notify_file_change(f.owner_id, f.id, 'updated',
+                           shared_with=_share_recipients(f))
         return jsonify({'message': 'Gespeichert', 'size': f.size}), 200
     except Exception as e:
         return jsonify({'error': f'Speichern fehlgeschlagen: {str(e)}'}), 500
@@ -353,9 +363,11 @@ def onlyoffice_config(file_id):
     AppSettings.set(f'oo_callback_{callback_key}', str(file_id))
 
     # Build the config
-    # The URLs must be reachable by OnlyOffice server (not the browser)
+    internal_url = os.environ.get('ONLYOFFICE_INTERNAL_URL', 'http://minicloud:5000')
-    base_url = request.host_url.rstrip('/')
+
-    token = request.args.get('token', '') or request.headers.get('Authorization', '').replace('Bearer ', '')
+    # Generate a one-time file access key (no JWT needed, simpler for OnlyOffice)
+    file_access_key = _secrets.token_urlsafe(32)
+    AppSettings.set(f'oo_file_{file_access_key}', f'{file_id}:{user.id}')
 
     config = {
         'available': True,
@@ -363,14 +375,15 @@ def onlyoffice_config(file_id):
         'config': {
             'document': {
                 'fileType': ext,
-                'key': f'{file_id}_{f.checksum or "0"}_{callback_key[:8]}',
+                'key': f'{file_id}_{int(datetime.now(timezone.utc).timestamp())}_{callback_key[:8]}',
                 'title': f.name,
-                'url': f'{base_url}/api/files/{file_id}/download?token={token}',
+                'url': f'{internal_url}/api/files/oo-download/{file_access_key}',
             },
             'documentType': doc_type,
             'editorConfig': {
-                'callbackUrl': f'{base_url}/api/files/onlyoffice-callback?key={callback_key}',
+                'callbackUrl': f'{internal_url}/api/files/onlyoffice-callback?key={callback_key}',
                 'mode': 'edit' if can_write else 'view',
+                'forcesavetype': 0,
                 'lang': 'de',
                 'user': {
                     'id': str(user.id),
@@ -380,7 +393,7 @@ def onlyoffice_config(file_id):
         },
     }
 
-    # Sign with JWT if secret is set
+    # Sign config with JWT for OnlyOffice validation
     jwt_secret = os.environ.get('JWT_SECRET_KEY', '')
     if jwt_secret:
         import jwt as pyjwt
@@ -389,57 +402,109 @@ def onlyoffice_config(file_id):
     return jsonify(config), 200
 
 
+@api_bp.route('/files/oo-download/<access_key>', methods=['GET'])
+def oo_download(access_key):
+    """Dedicated download endpoint for OnlyOffice - no JWT auth, uses one-time key."""
+    data = AppSettings.get(f'oo_file_{access_key}', '')
+    if not data:
+        return jsonify({'error': 'Ungueltiger Zugangsschluessel'}), 403
+
+    parts = data.split(':')
+    if len(parts) != 2:
+        return jsonify({'error': 'Ungueltiger Zugangsschluessel'}), 403
+
+    file_id = int(parts[0])
+    from app.models.file import File
+    f = db.session.get(File, file_id)
+    if not f:
+        return jsonify({'error': 'Datei nicht gefunden'}), 404
+
+    filepath = Path(current_app.config['UPLOAD_PATH']) / str(f.owner_id) / f.storage_path
+    if not filepath.exists():
+        return jsonify({'error': 'Datei nicht auf Datentraeger'}), 404
+
+    return send_file(str(filepath), mimetype=f.mime_type or 'application/octet-stream',
+                     as_attachment=False, download_name=f.name)
+
+
 @api_bp.route('/files/onlyoffice-callback', methods=['POST'])
 def onlyoffice_callback():
-    """Callback from OnlyOffice when document is saved."""
+    """Callback from OnlyOffice when document is saved.
-    import urllib.request
 
-    callback_key = request.args.get('key', '')
+    OnlyOffice sends status codes:
-    file_id_str = AppSettings.get(f'oo_callback_{callback_key}', '')
+    1 = editing, 2 = ready to save, 4 = closed no changes, 6 = force save
+    Must always return {"error": 0} for success.
+    """
+    try:
+        import jwt as pyjwt
+        import urllib.request
+        import shutil
 
-    if not file_id_str:
+        jwt_secret = os.environ.get('JWT_SECRET_KEY', '')
-        return jsonify({'error': 1}), 200  # OnlyOffice expects {"error": 0} for success
 
-    data = request.get_json()
+        # Get callback data - may be JWT-wrapped
-    status = data.get('status', 0)
+        data = request.get_json(silent=True) or {}
+        print(f'[OnlyOffice Callback] Raw status={data.get("status")}, key={request.args.get("key", "")}')
 
-    # Status 2 = document ready for saving, 6 = force save
+        # If body contains a JWT token, decode it to get the real data
-    if status in (2, 6):
+        if 'token' in data and jwt_secret:
-        download_url = data.get('url', '')
-        if download_url:
             try:
-                from app.models.file import File
+                decoded = pyjwt.decode(data['token'], jwt_secret, algorithms=['HS256'])
-                file_id = int(file_id_str)
+                data = decoded
-                f = db.session.get(File, file_id)
-                if f:
-                    filepath = Path(current_app.config['UPLOAD_PATH']) / str(f.owner_id) / f.storage_path
-
-                    # Download the saved document from OnlyOffice
-                    urllib.request.urlretrieve(download_url, str(filepath))
-
-                    # Update metadata
-                    f.size = os.path.getsize(str(filepath))
-                    h = hashlib.sha256()
-                    with open(str(filepath), 'rb') as fh:
-                        for chunk in iter(lambda: fh.read(8192), b''):
-                            h.update(chunk)
-                    f.checksum = h.hexdigest()
-                    f.updated_at = datetime.now(timezone.utc)
-                    db.session.commit()
             except Exception as e:
-                print(f'[OnlyOffice Callback] Error: {e}')
+                print(f'[OnlyOffice Callback] Body JWT decode failed (using raw data): {e}')
-                return jsonify({'error': 1}), 200
 
-    # Status 4 = closed without changes
+        status = data.get('status', 0)
-    if status in (2, 4, 6):
+        callback_key = request.args.get('key', '')
-        # Cleanup callback key
+
-        try:
+        # Status 2 or 6: save the document
-            setting = db.session.get(AppSettings, f'oo_callback_{callback_key}')
+        if status in (2, 6):
-            if setting:
+            file_id_str = AppSettings.get(f'oo_callback_{callback_key}', '')
-                db.session.delete(setting)
+            if file_id_str:
-                db.session.commit()
+                download_url = data.get('url', '')
-        except Exception:
+                if download_url:
-            pass
+                    from app.models.file import File
+                    file_id = int(file_id_str)
+                    f = db.session.get(File, file_id)
+                    if f and f.storage_path:
+                        filepath = Path(current_app.config['UPLOAD_PATH']) / str(f.owner_id) / f.storage_path
+                        print(f'[OnlyOffice Callback] Saving file {f.name} from {download_url}')
+
+                        # Download saved doc from OnlyOffice
+                        req = urllib.request.Request(download_url)
+                        with urllib.request.urlopen(req, timeout=30) as resp, \
+                                open(str(filepath), 'wb') as out:
+                            shutil.copyfileobj(resp, out)
+
+                        # Update metadata
+                        f.size = os.path.getsize(str(filepath))
+                        h = hashlib.sha256()
+                        with open(str(filepath), 'rb') as fh:
+                            for chunk in iter(lambda: fh.read(8192), b''):
+                                h.update(chunk)
+                        f.checksum = h.hexdigest()
+                        f.updated_at = datetime.now(timezone.utc)
+                        db.session.commit()
+                        notify_file_change(f.owner_id, f.id, 'updated',
+                                           shared_with=_share_recipients(f))
+                        print(f'[OnlyOffice Callback] File saved: {f.name} ({f.size} bytes)')
+
+        # Status 2, 4, 6: cleanup
+        if status in (2, 4, 6):
+            try:
+                setting = db.session.get(AppSettings, f'oo_callback_{callback_key}')
+                if setting:
+                    db.session.delete(setting)
+                    db.session.commit()
+            except Exception:
+                pass
+
+    except Exception as e:
+        print(f'[OnlyOffice Callback] ERROR: {e}')
+        import traceback
+        traceback.print_exc()
+        # Still return error: 0 so OnlyOffice doesn't retry endlessly
+        return jsonify({'error': 0}), 200
 
     return jsonify({'error': 0}), 200
 

backend/app/api/tasks.py

@@ -0,0 +1,590 @@
+"""REST API for task lists / tasks (VTODO).
+
+Mirror der calendar.py-Architektur: TaskList = Calendar-aehnliche Sammlung,
+Task = VTODO. CalDAV-Anbindung erfolgt in app/dav/caldav.py: TaskLists
+erscheinen als Kalender-Collection mit supported-calendar-component-set
+auf VTODO und unter URL /dav/<user>/tl-<id>/.
+"""
+from __future__ import annotations
+
+import re
+import uuid
+from datetime import datetime, timezone
+
+from flask import request, jsonify, Response
+
+from app.api import api_bp
+from app.api.auth import token_required
+from app.extensions import db
+from app.models.task import TaskList, Task, TaskListShare
+from app.models.user import User
+from app.services.events import notify_tasklist_change
+
+
+# ---------------------------------------------------------------------------
+# Access helpers
+# ---------------------------------------------------------------------------
+
+def _list_recipients(tl: TaskList):
+    return [s.shared_with_id for s in
+            TaskListShare.query.filter_by(task_list_id=tl.id).all()]
+
+
+def _get_list_or_err(list_id, user, need_write=False):
+    tl = db.session.get(TaskList, list_id)
+    if not tl:
+        return None, (jsonify({'error': 'Aufgabenliste nicht gefunden'}), 404)
+    if tl.owner_id == user.id:
+        return tl, None
+    share = TaskListShare.query.filter_by(
+        task_list_id=list_id, shared_with_id=user.id
+    ).first()
+    if not share:
+        return None, (jsonify({'error': 'Zugriff verweigert'}), 403)
+    if need_write and share.permission != 'readwrite':
+        return None, (jsonify({'error': 'Schreibzugriff verweigert'}), 403)
+    return tl, None
+
+
+# ---------------------------------------------------------------------------
+# VTODO build / parse
+# ---------------------------------------------------------------------------
+
+def _fmt_dt(dt: datetime | None) -> str | None:
+    if not dt:
+        return None
+    if dt.tzinfo is None:
+        dt = dt.replace(tzinfo=timezone.utc)
+    return dt.astimezone(timezone.utc).strftime('%Y%m%dT%H%M%SZ')
+
+
+def build_vtodo(task: Task) -> str:
+    lines = ['BEGIN:VTODO', f'UID:{task.uid}',
+             f'DTSTAMP:{_fmt_dt(datetime.now(timezone.utc))}',
+             f'SUMMARY:{(task.summary or "").replace(chr(10), " ")}']
+    if task.description:
+        lines.append(f'DESCRIPTION:{task.description.replace(chr(10), chr(92) + "n")}')
+    if task.status:
+        lines.append(f'STATUS:{task.status}')
+    if task.priority is not None:
+        lines.append(f'PRIORITY:{task.priority}')
+    if task.percent_complete is not None:
+        lines.append(f'PERCENT-COMPLETE:{task.percent_complete}')
+    if task.due:
+        lines.append(f'DUE:{_fmt_dt(task.due)}')
+    if task.dtstart:
+        lines.append(f'DTSTART:{_fmt_dt(task.dtstart)}')
+    if task.completed_at:
+        lines.append(f'COMPLETED:{_fmt_dt(task.completed_at)}')
+    if task.categories:
+        lines.append(f'CATEGORIES:{task.categories}')
+    lines.append('END:VTODO')
+    return '\r\n'.join(lines)
+
+
+def _unfold(text: str):
+    out, current = [], ''
+    for line in text.replace('\r\n', '\n').split('\n'):
+        if line.startswith((' ', '\t')) and current:
+            current += line[1:]
+        else:
+            if current:
+                out.append(current)
+            current = line
+    if current:
+        out.append(current)
+    return out
+
+
+def _parse_dt(value: str) -> datetime | None:
+    value = value.strip()
+    try:
+        if value.endswith('Z'):
+            return datetime.strptime(value, '%Y%m%dT%H%M%SZ').replace(tzinfo=timezone.utc)
+        if 'T' in value:
+            return datetime.strptime(value, '%Y%m%dT%H%M%S')
+        return datetime.strptime(value, '%Y%m%d')
+    except ValueError:
+        try:
+            return datetime.fromisoformat(value)
+        except ValueError:
+            return None
+
+
+def parse_vtodo(raw: str) -> dict | None:
+    if 'BEGIN:VTODO' not in raw.upper():
+        return None
+    result: dict = {}
+    in_block = False
+    for line in _unfold(raw):
+        upper = line.upper()
+        if upper.startswith('BEGIN:VTODO'):
+            in_block = True
+            continue
+        if upper.startswith('END:VTODO'):
+            break
+        if not in_block or ':' not in line:
+            continue
+        key, _, value = line.partition(':')
+        name = key.split(';')[0].upper()
+        if name == 'UID':
+            result['uid'] = value.strip()
+        elif name == 'SUMMARY':
+            result['summary'] = value.strip()
+        elif name == 'DESCRIPTION':
+            result['description'] = value.replace('\\n', '\n').replace('\\,', ',').strip()
+        elif name == 'STATUS':
+            result['status'] = value.strip().upper()
+        elif name == 'PRIORITY':
+            try:
+                result['priority'] = int(value.strip())
+            except ValueError:
+                pass
+        elif name == 'PERCENT-COMPLETE':
+            try:
+                result['percent_complete'] = int(value.strip())
+            except ValueError:
+                pass
+        elif name == 'DUE':
+            result['due'] = _parse_dt(value)
+        elif name == 'DTSTART':
+            result['dtstart'] = _parse_dt(value)
+        elif name == 'COMPLETED':
+            result['completed_at'] = _parse_dt(value)
+        elif name == 'CATEGORIES':
+            result['categories'] = value.strip()
+    return result if result.get('summary') or result.get('uid') else None
+
+
+def _apply(task: Task, data: dict):
+    if 'summary' in data:
+        task.summary = (data.get('summary') or '').strip() or None
+    if 'description' in data:
+        task.description = (data.get('description') or '').strip() or None
+    if 'status' in data:
+        s = (data.get('status') or '').upper().strip() or None
+        task.status = s
+        if s == 'COMPLETED' and not task.completed_at:
+            task.completed_at = datetime.now(timezone.utc)
+            task.percent_complete = 100
+        elif s != 'COMPLETED':
+            task.completed_at = None
+    if 'priority' in data:
+        task.priority = data['priority'] if data['priority'] is not None else None
+    if 'percent_complete' in data:
+        task.percent_complete = data['percent_complete']
+    if 'due' in data:
+        v = data['due']
+        task.due = datetime.fromisoformat(v) if v else None
+    if 'dtstart' in data:
+        v = data['dtstart']
+        task.dtstart = datetime.fromisoformat(v) if v else None
+    if 'completed_at' in data:
+        v = data['completed_at']
+        task.completed_at = datetime.fromisoformat(v) if v else None
+    if 'categories' in data:
+        cats = data['categories']
+        if isinstance(cats, list):
+            task.categories = ','.join(c.strip() for c in cats if c and c.strip()) or None
+        else:
+            task.categories = (cats or '').strip() or None
+
+
+# ---------------------------------------------------------------------------
+# REST endpoints - lists
+# ---------------------------------------------------------------------------
+
+@api_bp.route('/tasklists', methods=['GET'])
+@token_required
+def list_tasklists():
+    user = request.current_user
+    own = TaskList.query.filter_by(owner_id=user.id).all()
+    shared = TaskListShare.query.filter_by(shared_with_id=user.id).all()
+    out = []
+    for tl in own:
+        d = tl.to_dict()
+        d['permission'] = 'owner'
+        d['task_count'] = tl.tasks.count()
+        out.append(d)
+    for s in shared:
+        tl = s.task_list
+        if not tl:
+            continue
+        d = tl.to_dict()
+        d['permission'] = s.permission
+        owner = tl.owner
+        d['owner_name'] = owner.username if owner else ''
+        d['owner_full_name'] = owner.full_name if owner else ''
+        d['owner_display_name'] = owner.display_name if owner else ''
+        d['task_count'] = tl.tasks.count()
+        if s.color:
+            d['color'] = s.color
+        out.append(d)
+    return jsonify(out), 200
+
+
+@api_bp.route('/tasklists', methods=['POST'])
+@token_required
+def create_tasklist():
+    user = request.current_user
+    data = request.get_json() or {}
+    name = (data.get('name') or '').strip()
+    if not name:
+        return jsonify({'error': 'Name erforderlich'}), 400
+    tl = TaskList(owner_id=user.id, name=name,
+                  color=data.get('color') or '#10b981',
+                  description=(data.get('description') or '').strip() or None)
+    db.session.add(tl)
+    db.session.commit()
+    notify_tasklist_change(user.id, tl.id, 'created')
+    return jsonify(tl.to_dict()), 201
+
+
+@api_bp.route('/tasklists/<int:list_id>', methods=['PUT'])
+@token_required
+def update_tasklist(list_id):
+    user = request.current_user
+    tl, err = _get_list_or_err(list_id, user, need_write=True)
+    if err:
+        return err
+    if tl.owner_id != user.id:
+        return jsonify({'error': 'Nur Eigentuemer kann die Liste umbenennen'}), 403
+    data = request.get_json() or {}
+    if 'name' in data:
+        tl.name = data['name'].strip()
+    if 'color' in data:
+        tl.color = data['color']
+    if 'description' in data:
+        tl.description = (data['description'] or '').strip() or None
+    db.session.commit()
+    notify_tasklist_change(tl.owner_id, tl.id, 'updated', shared_with=_list_recipients(tl))
+    return jsonify(tl.to_dict()), 200
+
+
+@api_bp.route('/tasklists/<int:list_id>/my-color', methods=['PUT'])
+@token_required
+def set_my_tasklist_color(list_id):
+    user = request.current_user
+    tl = db.session.get(TaskList, list_id)
+    if not tl:
+        return jsonify({'error': 'Nicht gefunden'}), 404
+    color = (request.get_json() or {}).get('color')
+    if not color:
+        return jsonify({'error': 'color erforderlich'}), 400
+    if tl.owner_id == user.id:
+        tl.color = color
+        db.session.commit()
+        return jsonify({'color': tl.color}), 200
+    share = TaskListShare.query.filter_by(task_list_id=list_id, shared_with_id=user.id).first()
+    if not share:
+        return jsonify({'error': 'Zugriff verweigert'}), 403
+    share.color = color
+    db.session.commit()
+    return jsonify({'color': share.color}), 200
+
+
+@api_bp.route('/tasklists/<int:list_id>', methods=['DELETE'])
+@token_required
+def delete_tasklist(list_id):
+    user = request.current_user
+    tl = db.session.get(TaskList, list_id)
+    if not tl or tl.owner_id != user.id:
+        return jsonify({'error': 'Nur Eigentuemer kann loeschen'}), 403
+    recipients = _list_recipients(tl)
+    db.session.delete(tl)
+    db.session.commit()
+    notify_tasklist_change(user.id, list_id, 'deleted', shared_with=recipients)
+    return jsonify({'message': 'Aufgabenliste geloescht'}), 200
+
+
+# ---------------------------------------------------------------------------
+# REST endpoints - tasks
+# ---------------------------------------------------------------------------
+
+@api_bp.route('/tasklists/<int:list_id>/tasks', methods=['GET'])
+@token_required
+def list_tasks(list_id):
+    user = request.current_user
+    tl, err = _get_list_or_err(list_id, user)
+    if err:
+        return err
+    show_done = (request.args.get('include_done') or 'true').lower() != 'false'
+    q = Task.query.filter_by(task_list_id=list_id)
+    if not show_done:
+        q = q.filter((Task.status.is_(None)) | (Task.status != 'COMPLETED'))
+    tasks = q.order_by(Task.due.asc().nullslast(), Task.priority.desc().nullslast(), Task.id).all()
+    return jsonify([t.to_dict() for t in tasks]), 200
+
+
+@api_bp.route('/tasklists/<int:list_id>/tasks', methods=['POST'])
+@token_required
+def create_task(list_id):
+    user = request.current_user
+    tl, err = _get_list_or_err(list_id, user, need_write=True)
+    if err:
+        return err
+    data = request.get_json() or {}
+    if not (data.get('summary') or '').strip():
+        return jsonify({'error': 'Titel erforderlich'}), 400
+    task = Task(task_list_id=list_id, uid=str(uuid.uuid4()), ical_data='')
+    _apply(task, data)
+    if not task.status:
+        task.status = 'NEEDS-ACTION'
+    task.ical_data = build_vtodo(task)
+    db.session.add(task)
+    db.session.commit()
+    notify_tasklist_change(tl.owner_id, tl.id, 'task', shared_with=_list_recipients(tl))
+    return jsonify(task.to_dict()), 201
+
+
+@api_bp.route('/tasks/<int:task_id>', methods=['GET'])
+@token_required
+def get_task(task_id):
+    user = request.current_user
+    task = db.session.get(Task, task_id)
+    if not task:
+        return jsonify({'error': 'Aufgabe nicht gefunden'}), 404
+    tl, err = _get_list_or_err(task.task_list_id, user)
+    if err:
+        return err
+    return jsonify(task.to_dict()), 200
+
+
+@api_bp.route('/tasks/<int:task_id>', methods=['PUT'])
+@token_required
+def update_task(task_id):
+    user = request.current_user
+    task = db.session.get(Task, task_id)
+    if not task:
+        return jsonify({'error': 'Aufgabe nicht gefunden'}), 404
+    tl, err = _get_list_or_err(task.task_list_id, user, need_write=True)
+    if err:
+        return err
+    data = request.get_json() or {}
+    if 'task_list_id' in data and data['task_list_id'] != task.task_list_id:
+        new_tl, e2 = _get_list_or_err(data['task_list_id'], user, need_write=True)
+        if e2:
+            return e2
+        task.task_list_id = data['task_list_id']
+    _apply(task, data)
+    task.ical_data = build_vtodo(task)
+    task.updated_at = datetime.now(timezone.utc)
+    db.session.commit()
+    notify_tasklist_change(tl.owner_id, tl.id, 'task', shared_with=_list_recipients(tl))
+    return jsonify(task.to_dict()), 200
+
+
+@api_bp.route('/tasks/<int:task_id>', methods=['DELETE'])
+@token_required
+def delete_task(task_id):
+    user = request.current_user
+    task = db.session.get(Task, task_id)
+    if not task:
+        return jsonify({'error': 'Aufgabe nicht gefunden'}), 404
+    tl, err = _get_list_or_err(task.task_list_id, user, need_write=True)
+    if err:
+        return err
+    db.session.delete(task)
+    db.session.commit()
+    notify_tasklist_change(tl.owner_id, tl.id, 'task', shared_with=_list_recipients(tl))
+    return jsonify({'message': 'Aufgabe geloescht'}), 200
+
+
+# ---------------------------------------------------------------------------
+# Sharing
+# ---------------------------------------------------------------------------
+
+@api_bp.route('/tasklists/<int:list_id>/share', methods=['POST'])
+@token_required
+def share_tasklist(list_id):
+    user = request.current_user
+    tl = db.session.get(TaskList, list_id)
+    if not tl or tl.owner_id != user.id:
+        return jsonify({'error': 'Nur Eigentuemer kann teilen'}), 403
+    data = request.get_json() or {}
+    username = (data.get('username') or '').strip()
+    permission = data.get('permission', 'read')
+    if permission not in ('read', 'readwrite'):
+        return jsonify({'error': 'Ungueltige Berechtigung'}), 400
+    target = User.query.filter_by(username=username).first()
+    if not target:
+        return jsonify({'error': 'Benutzer nicht gefunden'}), 404
+    if target.id == user.id:
+        return jsonify({'error': 'Kann nicht mit sich selbst teilen'}), 400
+    existing = TaskListShare.query.filter_by(task_list_id=list_id, shared_with_id=target.id).first()
+    if existing:
+        existing.permission = permission
+    else:
+        db.session.add(TaskListShare(task_list_id=list_id, shared_with_id=target.id,
+                                     permission=permission))
+    db.session.commit()
+    notify_tasklist_change(tl.owner_id, tl.id, 'share',
+                           shared_with=[target.id, *_list_recipients(tl)])
+    return jsonify({'message': f'Geteilt mit {username}'}), 200
+
+
+@api_bp.route('/tasklists/<int:list_id>/shares', methods=['GET'])
+@token_required
+def list_tasklist_shares(list_id):
+    user = request.current_user
+    tl = db.session.get(TaskList, list_id)
+    if not tl or tl.owner_id != user.id:
+        return jsonify({'error': 'Nicht gefunden'}), 404
+    shares = TaskListShare.query.filter_by(task_list_id=list_id).all()
+    return jsonify([{
+        'id': s.id, 'user_id': s.shared_with_id,
+        'username': s.shared_with.username, 'permission': s.permission,
+    } for s in shares]), 200
+
+
+@api_bp.route('/tasklists/<int:list_id>/shares/<int:share_id>', methods=['DELETE'])
+@token_required
+def remove_tasklist_share(list_id, share_id):
+    user = request.current_user
+    tl = db.session.get(TaskList, list_id)
+    if not tl or tl.owner_id != user.id:
+        return jsonify({'error': 'Nicht gefunden'}), 404
+    share = db.session.get(TaskListShare, share_id)
+    if not share or share.task_list_id != list_id:
+        return jsonify({'error': 'Freigabe nicht gefunden'}), 404
+    target_id = share.shared_with_id
+    db.session.delete(share)
+    db.session.commit()
+    notify_tasklist_change(tl.owner_id, tl.id, 'share',
+                           shared_with=[target_id, *_list_recipients(tl)])
+    return jsonify({'message': 'Freigabe entfernt'}), 200
+
+
+# ---------------------------------------------------------------------------
+# Import / Export (.ics with VTODO; CSV)
+# ---------------------------------------------------------------------------
+
+@api_bp.route('/tasklists/<int:list_id>/export', methods=['GET'])
+@token_required
+def export_tasklist(list_id):
+    import csv
+    import io
+    user = request.current_user
+    tl, err = _get_list_or_err(list_id, user)
+    if err:
+        return err
+    fmt = (request.args.get('format') or 'ics').lower()
+    tasks = Task.query.filter_by(task_list_id=list_id).all()
+    safe = re.sub(r'[^A-Za-z0-9._-]+', '_', tl.name or 'aufgaben') or 'aufgaben'
+
+    if fmt == 'ics':
+        lines = ['BEGIN:VCALENDAR', 'VERSION:2.0', 'PRODID:-//Mini-Cloud//DE', 'CALSCALE:GREGORIAN']
+        for t in tasks:
+            block = (t.ical_data or '').strip() or build_vtodo(t)
+            lines.append(block)
+        lines.append('END:VCALENDAR')
+        return Response(
+            '\r\n'.join(lines) + '\r\n',
+            mimetype='text/calendar; charset=utf-8',
+            headers={'Content-Disposition': f'attachment; filename="{safe}.ics"'},
+        )
+    if fmt == 'csv':
+        out = io.StringIO()
+        w = csv.writer(out, delimiter=';', quoting=csv.QUOTE_ALL)
+        w.writerow(['summary', 'status', 'priority', 'percent_complete',
+                    'due', 'dtstart', 'completed_at', 'categories', 'description', 'uid'])
+        for t in tasks:
+            w.writerow([
+                t.summary or '', t.status or '',
+                t.priority if t.priority is not None else '',
+                t.percent_complete if t.percent_complete is not None else '',
+                t.due.isoformat() if t.due else '',
+                t.dtstart.isoformat() if t.dtstart else '',
+                t.completed_at.isoformat() if t.completed_at else '',
+                t.categories or '',
+                (t.description or '').replace('\r\n', ' ').replace('\n', ' '),
+                t.uid or '',
+            ])
+        return Response(
+            '\ufeff' + out.getvalue(), mimetype='text/csv; charset=utf-8',
+            headers={'Content-Disposition': f'attachment; filename="{safe}.csv"'},
+        )
+    return jsonify({'error': 'Unbekanntes Format'}), 400
+
+
+@api_bp.route('/tasklists/<int:list_id>/import', methods=['POST'])
+@token_required
+def import_tasklist(list_id):
+    import csv
+    import io
+    user = request.current_user
+    tl, err = _get_list_or_err(list_id, user, need_write=True)
+    if err:
+        return err
+    file = request.files.get('file')
+    if not file:
+        return jsonify({'error': 'Keine Datei'}), 400
+    raw = file.read()
+    try:
+        text = raw.decode('utf-8-sig')
+    except UnicodeDecodeError:
+        text = raw.decode('latin-1', errors='replace')
+    name = (file.filename or '').lower()
+    imported, skipped = 0, 0
+
+    def _save(parsed: dict, ical_block: str | None = None):
+        nonlocal imported, skipped
+        if not parsed.get('summary'):
+            skipped += 1
+            return
+        uid = parsed.get('uid') or str(uuid.uuid4())
+        existing = Task.query.filter_by(task_list_id=list_id, uid=uid).first()
+        t = existing or Task(task_list_id=list_id, uid=uid, ical_data='')
+        t.summary = parsed.get('summary')
+        t.description = parsed.get('description')
+        t.status = parsed.get('status') or 'NEEDS-ACTION'
+        t.priority = parsed.get('priority')
+        t.percent_complete = parsed.get('percent_complete')
+        t.due = parsed.get('due')
+        t.dtstart = parsed.get('dtstart')
+        t.completed_at = parsed.get('completed_at')
+        cats = parsed.get('categories')
+        if isinstance(cats, list):
+            t.categories = ','.join(cats)
+        elif isinstance(cats, str):
+            t.categories = cats or None
+        t.ical_data = (ical_block or '').strip() or build_vtodo(t)
+        if not existing:
+            db.session.add(t)
+        imported += 1
+
+    if name.endswith('.csv') or (b';' in raw[:200] and b'BEGIN:VCALENDAR' not in raw[:200]):
+        reader = csv.DictReader(__import__('io').StringIO(text), delimiter=';')
+        if not reader.fieldnames or len(reader.fieldnames) < 2:
+            reader = csv.DictReader(__import__('io').StringIO(text), delimiter=',')
+        for row in reader:
+            row = {k.strip().lower(): (v or '').strip() for k, v in row.items() if k}
+            try:
+                due = datetime.fromisoformat(row['due']) if row.get('due') else None
+            except ValueError:
+                due = None
+            _save({
+                'uid': row.get('uid'),
+                'summary': row.get('summary') or row.get('titel'),
+                'description': row.get('description') or row.get('beschreibung'),
+                'status': (row.get('status') or '').upper() or None,
+                'priority': int(row['priority']) if row.get('priority', '').isdigit() else None,
+                'percent_complete': int(row['percent_complete']) if row.get('percent_complete', '').isdigit() else None,
+                'due': due,
+                'categories': row.get('categories') or row.get('kategorien'),
+            })
+    else:
+        blocks = re.findall(r'BEGIN:VTODO.*?END:VTODO', text, flags=re.DOTALL | re.IGNORECASE)
+        if not blocks:
+            return jsonify({'error': 'Keine VTODO-Daten gefunden'}), 400
+        for block in blocks:
+            parsed = parse_vtodo(block)
+            if not parsed:
+                skipped += 1
+                continue
+            _save(parsed, ical_block=block)
+
+    db.session.commit()
+    if imported:
+        notify_tasklist_change(tl.owner_id, tl.id, 'task', shared_with=_list_recipients(tl))
+    return jsonify({'imported': imported, 'skipped': skipped}), 200

backend/app/api/users.py

@@ -145,6 +145,12 @@ def delete_user(user_id):
 @api_bp.route('/settings', methods=['GET'])
 @admin_required
 def get_settings():
+    import time as _time
+    from datetime import datetime as _dt
+    try:
+        tzname = _time.strftime('%Z')
+    except Exception:
+        tzname = ''
     return jsonify({
         'public_registration': AppSettings.get_bool('public_registration', default=True),
         'system_smtp_host': AppSettings.get('system_smtp_host', ''),
@@ -155,6 +161,11 @@ def get_settings():
         'system_email_from': AppSettings.get('system_email_from', ''),
         'onlyoffice_url': os.environ.get('ONLYOFFICE_URL', ''),
         'onlyoffice_configured': bool(os.environ.get('ONLYOFFICE_URL', '')),
+        # Read-only system info aus der .env
+        'timezone': os.environ.get('TZ', 'Europe/Berlin'),
+        'timezone_abbr': tzname,
+        'server_time': _dt.now().isoformat(timespec='seconds'),
+        'ntp_server': os.environ.get('NTP_SERVER', ''),
     }), 200
 
 
@@ -270,6 +281,31 @@ def create_invite_link():
 
 # --- User search (for sharing dialogs) ---
 
+@api_bp.route('/auth/me', methods=['GET'])
+@token_required
+def get_me():
+    return jsonify(request.current_user.to_dict(include_email=True)), 200
+
+
+@api_bp.route('/auth/me', methods=['PUT'])
+@token_required
+def update_me():
+    user = request.current_user
+    data = request.get_json() or {}
+    if 'first_name' in data:
+        user.first_name = (data.get('first_name') or '').strip() or None
+    if 'last_name' in data:
+        user.last_name = (data.get('last_name') or '').strip() or None
+    if 'email' in data:
+        email = (data.get('email') or '').strip() or None
+        if email and email != user.email:
+            if User.query.filter(User.email == email, User.id != user.id).first():
+                return jsonify({'error': 'E-Mail ist bereits vergeben'}), 409
+        user.email = email
+    db.session.commit()
+    return jsonify(user.to_dict(include_email=True)), 200
+
+
 @api_bp.route('/users/search', methods=['GET'])
 @token_required
 def search_users():
@@ -278,13 +314,19 @@ def search_users():
     if len(query) < 2:
         return jsonify([]), 200
 
+    like = f'%{query}%'
     users = User.query.filter(
-        User.username.ilike(f'%{query}%'),
+        (User.username.ilike(like)) | (User.first_name.ilike(like)) | (User.last_name.ilike(like)),
         User.id != request.current_user.id,
         User.is_active == True,
     ).limit(10).all()
 
-    return jsonify([{'id': u.id, 'username': u.username} for u in users]), 200
+    return jsonify([{
+        'id': u.id,
+        'username': u.username,
+        'full_name': u.full_name,
+        'display_name': u.display_name,
+    } for u in users]), 200
 
 
 # --- Change password (non-admin, own account) ---

backend/app/config.py

@@ -40,3 +40,8 @@ class Config:
 
     # CORS
     FRONTEND_URL = os.environ.get('FRONTEND_URL', 'http://localhost:3000')
+
+    # Zeitzone (prozessweit, wirkt nach time.tzset())
+    TIMEZONE = os.environ.get('TZ', 'Europe/Berlin')
+    # NTP-Server fuer Offset-Check beim Start. Leerstring deaktiviert den Check.
+    NTP_SERVER = os.environ.get('NTP_SERVER', 'ptbtime1.ptb.de')

backend/app/dav/__init__.py

@@ -0,0 +1,6 @@
+from flask import Blueprint
+
+dav_bp = Blueprint('dav', __name__, url_prefix='/dav')
+
+from . import caldav   # noqa: F401,E402
+from . import carddav  # noqa: F401,E402

backend/app/dav/caldav.py

@@ -0,0 +1,780 @@
+"""Minimal CalDAV server (RFC 4791 subset).
+
+Implements the endpoints that Thunderbird, DAVx5 and Apple Calendar
+actually use in practice:
+
+  OPTIONS              - capability advertisement (DAV: 1, 2, calendar-access)
+  PROPFIND  Depth 0/1  - discovery chain + listings
+  REPORT    calendar-query + calendar-multiget
+  GET       single VCALENDAR resource
+  PUT       create/update VCALENDAR resource
+  DELETE    remove a resource or calendar collection
+
+Non-goals for this revision: ACL reports, free-busy, sync-token based
+incremental sync, scheduling (iTIP/iMIP). Clients fall back to full
+PROPFIND refresh when sync-token isn't advertised, which is fine for
+small personal calendars.
+"""
+from __future__ import annotations
+
+import re
+import uuid
+import xml.etree.ElementTree as ET
+from datetime import datetime, timezone
+from functools import wraps
+
+from flask import Response, request
+
+from app.extensions import db
+from app.models.calendar import Calendar, CalendarEvent, CalendarShare
+from app.models.user import User
+from app.services.events import notify_calendar_change
+
+
+def _cal_recipients(cal: 'Calendar'):
+    return [s.shared_with_id for s in
+            CalendarShare.query.filter_by(calendar_id=cal.id).all()]
+
+from . import dav_bp
+
+# ---------------------------------------------------------------------------
+# XML namespace plumbing
+# ---------------------------------------------------------------------------
+
+NS = {
+    'd': 'DAV:',
+    'c': 'urn:ietf:params:xml:ns:caldav',
+    'cs': 'http://calendarserver.org/ns/',
+    'ic': 'http://apple.com/ns/ical/',
+}
+for prefix, uri in NS.items():
+    ET.register_namespace('' if prefix == 'd' else prefix, uri)
+
+
+def _qn(prefix: str, local: str) -> str:
+    return f'{{{NS[prefix]}}}{local}'
+
+
+def _xml_response(root: ET.Element, status: int = 207) -> Response:
+    body = b'<?xml version="1.0" encoding="utf-8"?>\n' + ET.tostring(root, encoding='utf-8')
+    headers = {
+        'DAV': '1, 2, 3, calendar-access, addressbook',
+        'Content-Type': 'application/xml; charset=utf-8',
+    }
+    return Response(body, status=status, headers=headers)
+
+
+# ---------------------------------------------------------------------------
+# Authentication (HTTP Basic over the existing user table)
+# ---------------------------------------------------------------------------
+
+def _challenge() -> Response:
+    return Response(
+        'Authentication required', 401,
+        {'WWW-Authenticate': 'Basic realm="Mini-Cloud DAV"'}
+    )
+
+
+def basic_auth(f):
+    @wraps(f)
+    def wrapper(*args, **kwargs):
+        auth = request.authorization
+        if not auth or not auth.username or not auth.password:
+            return _challenge()
+        user = User.query.filter_by(username=auth.username).first()
+        if not user or not user.is_active or not user.check_password(auth.password):
+            return _challenge()
+        request.dav_user = user
+        return f(*args, **kwargs)
+    return wrapper
+
+
+# ---------------------------------------------------------------------------
+# Helpers
+# ---------------------------------------------------------------------------
+
+DAV_HEADERS = {
+    'DAV': '1, 2, 3, calendar-access, addressbook',
+}
+
+ALLOW_COLLECTION = 'OPTIONS, PROPFIND, REPORT, DELETE, MKCALENDAR'
+ALLOW_RESOURCE = 'OPTIONS, PROPFIND, GET, PUT, DELETE'
+
+
+def _etag_for_event(event: CalendarEvent) -> str:
+    ts = int((event.updated_at or event.created_at or datetime.now(timezone.utc)).timestamp() * 1000)
+    return f'"{event.id}-{ts}"'
+
+
+def _href_calendar(username: str, cal_id: int) -> str:
+    return f'/dav/{username}/cal-{cal_id}/'
+
+
+def _href_event(username: str, cal_id: int, uid: str) -> str:
+    return f'/dav/{username}/cal-{cal_id}/{uid}.ics'
+
+
+def _user_calendars(user: User):
+    return Calendar.query.filter_by(owner_id=user.id).all()
+
+
+def _parse_calendar_path(path_part: str):
+    """Input: "cal-42" -> 42, otherwise None."""
+    m = re.match(r'cal-(\d+)$', path_part)
+    return int(m.group(1)) if m else None
+
+
+def _calendar_for(user: User, cal_id: int):
+    cal = db.session.get(Calendar, cal_id)
+    if not cal or cal.owner_id != user.id:
+        return None
+    return cal
+
+
+# ---------------------------------------------------------------------------
+# OPTIONS (advertise DAV capabilities on any path)
+# ---------------------------------------------------------------------------
+
+@dav_bp.route('/', methods=['OPTIONS'])
+@dav_bp.route('/<path:subpath>', methods=['OPTIONS'])
+def options(subpath=''):
+    headers = {
+        **DAV_HEADERS,
+        'Allow': 'OPTIONS, PROPFIND, REPORT, GET, PUT, DELETE, MKCALENDAR',
+    }
+    return Response('', status=200, headers=headers)
+
+
+# ---------------------------------------------------------------------------
+# PROPFIND
+# ---------------------------------------------------------------------------
+
+def _make_response(href: str, populate_prop) -> ET.Element:
+    """Build a <response><href/><propstat><prop>...</prop><status>200</status>
+    </propstat></response> element. `populate_prop` is a callable that gets
+    the <prop> element and appends the actual property sub-elements to it."""
+    resp = ET.Element(_qn('d', 'response'))
+    ET.SubElement(resp, _qn('d', 'href')).text = href
+    propstat = ET.SubElement(resp, _qn('d', 'propstat'))
+    prop = ET.SubElement(propstat, _qn('d', 'prop'))
+    populate_prop(prop)
+    ET.SubElement(propstat, _qn('d', 'status')).text = 'HTTP/1.1 200 OK'
+    return resp
+
+
+def _root_response(href: str, user: User) -> ET.Element:
+    def populate(prop):
+        rt = ET.SubElement(prop, _qn('d', 'resourcetype'))
+        ET.SubElement(rt, _qn('d', 'collection'))
+        ET.SubElement(prop, _qn('d', 'displayname')).text = 'Mini-Cloud DAV'
+        cup = ET.SubElement(prop, _qn('d', 'current-user-principal'))
+        ET.SubElement(cup, _qn('d', 'href')).text = f'/dav/{user.username}/'
+    return _make_response(href, populate)
+
+
+def _principal_response(user: User) -> ET.Element:
+    href = f'/dav/{user.username}/'
+
+    def populate(prop):
+        rt = ET.SubElement(prop, _qn('d', 'resourcetype'))
+        ET.SubElement(rt, _qn('d', 'collection'))
+        ET.SubElement(rt, _qn('d', 'principal'))
+        ET.SubElement(prop, _qn('d', 'displayname')).text = user.username
+        cup = ET.SubElement(prop, _qn('d', 'current-user-principal'))
+        ET.SubElement(cup, _qn('d', 'href')).text = href
+        pu = ET.SubElement(prop, _qn('d', 'principal-URL'))
+        ET.SubElement(pu, _qn('d', 'href')).text = href
+        # Separate home-sets so clients (DAVx5!) don't mix calendars and
+        # addressbooks in the same listing.
+        cal_home = ET.SubElement(prop, _qn('c', 'calendar-home-set'))
+        ET.SubElement(cal_home, _qn('d', 'href')).text = f'/dav/{user.username}/calendars/'
+        ab_home = ET.SubElement(prop, '{urn:ietf:params:xml:ns:carddav}addressbook-home-set')
+        ET.SubElement(ab_home, _qn('d', 'href')).text = f'/dav/{user.username}/addressbooks/'
+    return _make_response(href, populate)
+
+
+def _calendar_response(user: User, cal: Calendar) -> ET.Element:
+    href = _href_calendar(user.username, cal.id)
+
+    def populate(prop):
+        rt = ET.SubElement(prop, _qn('d', 'resourcetype'))
+        ET.SubElement(rt, _qn('d', 'collection'))
+        ET.SubElement(rt, _qn('c', 'calendar'))
+        ET.SubElement(prop, _qn('d', 'displayname')).text = cal.name
+        ET.SubElement(prop, _qn('c', 'calendar-description')).text = cal.description or ''
+        supported = ET.SubElement(prop, _qn('c', 'supported-calendar-component-set'))
+        comp = ET.SubElement(supported, _qn('c', 'comp'))
+        comp.set('name', 'VEVENT')
+        # supported-report-set: advertise which REPORTs this collection handles
+        srs = ET.SubElement(prop, _qn('d', 'supported-report-set'))
+        for report_name in ('calendar-query', 'calendar-multiget'):
+            sup = ET.SubElement(srs, _qn('d', 'supported-report'))
+            rep = ET.SubElement(sup, _qn('d', 'report'))
+            ET.SubElement(rep, _qn('c', report_name))
+        ET.SubElement(prop, _qn('ic', 'calendar-color')).text = cal.color or '#3788d8'
+        ET.SubElement(prop, _qn('cs', 'getctag')).text = _calendar_ctag(cal)
+        # current-user-privilege-set: advertise what the authenticated user is
+        # allowed to do. DAVx5 checks this to decide read-only vs read-write.
+        cups = ET.SubElement(prop, _qn('d', 'current-user-privilege-set'))
+        for priv_name in ('read', 'write', 'write-properties', 'write-content', 'bind', 'unbind'):
+            p = ET.SubElement(cups, _qn('d', 'privilege'))
+            ET.SubElement(p, _qn('d', priv_name))
+    return _make_response(href, populate)
+
+
+def _calendar_ctag(cal: Calendar) -> str:
+    """Collection tag: changes when any event in the calendar changes."""
+    last = db.session.query(db.func.max(CalendarEvent.updated_at)).filter_by(calendar_id=cal.id).scalar()
+    ts = int((last or cal.updated_at or datetime.now(timezone.utc)).timestamp())
+    return f'"{cal.id}-{ts}"'
+
+
+def _event_response(user: User, cal: Calendar, event: CalendarEvent, include_data: bool = False) -> ET.Element:
+    href = _href_event(user.username, cal.id, event.uid)
+
+    def populate(prop):
+        ET.SubElement(prop, _qn('d', 'getetag')).text = _etag_for_event(event)
+        ET.SubElement(prop, _qn('d', 'getcontenttype')).text = \
+            'text/calendar; charset=utf-8; component=VEVENT'
+        ET.SubElement(prop, _qn('d', 'resourcetype'))  # empty -> regular resource
+        if include_data:
+            ET.SubElement(prop, _qn('c', 'calendar-data')).text = _wrap_vcalendar(cal, event)
+    return _make_response(href, populate)
+
+
+def _wrap_vcalendar(cal: Calendar, event: CalendarEvent) -> str:
+    """Return a full VCALENDAR envelope around the event's ical_data."""
+    lines = [
+        'BEGIN:VCALENDAR',
+        'VERSION:2.0',
+        'PRODID:-//Mini-Cloud//DE',
+        'CALSCALE:GREGORIAN',
+        event.ical_data.strip() if event.ical_data else '',
+        'END:VCALENDAR',
+    ]
+    return '\r\n'.join(lines)
+
+
+@dav_bp.route('/', methods=['PROPFIND'])
+@dav_bp.route('/<path:subpath>', methods=['PROPFIND'])
+@basic_auth
+def propfind(subpath=''):
+    user: User = request.dav_user
+    depth = request.headers.get('Depth', '0')
+
+    multistatus = ET.Element(_qn('d', 'multistatus'))
+    parts = [p for p in subpath.split('/') if p]
+
+    # /dav/  (root) or / (when called via the app-level shortcut for DAVx5)
+    if not parts:
+        # Use the actual request path so Clients wie DAVx5 die href passend
+        # zu ihrer Anfrage sehen.
+        request_href = request.path if request.path.endswith('/') else request.path + '/'
+        multistatus.append(_root_response(request_href, user))
+        if depth != '0':
+            multistatus.append(_principal_response(user))
+        return _xml_response(multistatus)
+
+    # /dav/<username>/ : nur der Principal. Clients MUESSEN den Home-Sets
+    # (calendar-home-set / addressbook-home-set) folgen - sonst wuerden die
+    # Container hier faelschlich als leere Kalender angezeigt (DAVx5).
+    if len(parts) == 1:
+        if parts[0] != user.username:
+            return Response('', 403)
+        multistatus.append(_principal_response(user))
+        return _xml_response(multistatus)
+
+    # /dav/<username>/calendars/ : Kalender + Aufgabenlisten (DAVx5 erkennt
+    # VTODO-Listen automatisch an supported-calendar-component-set).
+    if len(parts) == 2 and parts[1] == 'calendars':
+        if parts[0] != user.username:
+            return Response('', 403)
+        container = ET.Element(_qn('d', 'response'))
+        ET.SubElement(container, _qn('d', 'href')).text = f'/dav/{user.username}/calendars/'
+        propstat = ET.SubElement(container, _qn('d', 'propstat'))
+        prop = ET.SubElement(propstat, _qn('d', 'prop'))
+        rt = ET.SubElement(prop, _qn('d', 'resourcetype'))
+        ET.SubElement(rt, _qn('d', 'collection'))
+        ET.SubElement(prop, _qn('d', 'displayname')).text = 'Kalender'
+        ET.SubElement(propstat, _qn('d', 'status')).text = 'HTTP/1.1 200 OK'
+        multistatus.append(container)
+        if depth != '0':
+            for cal in _user_calendars(user):
+                multistatus.append(_calendar_response(user, cal))
+            from .taskdav import user_lists, list_response
+            for tl in user_lists(user):
+                multistatus.append(list_response(user, tl))
+        return _xml_response(multistatus)
+
+    # /dav/<username>/addressbooks/ : only addressbook collections
+    if len(parts) == 2 and parts[1] == 'addressbooks':
+        if parts[0] != user.username:
+            return Response('', 403)
+        from .carddav import _addressbook_response, _user_addressbooks
+        container = ET.Element(_qn('d', 'response'))
+        ET.SubElement(container, _qn('d', 'href')).text = f'/dav/{user.username}/addressbooks/'
+        propstat = ET.SubElement(container, _qn('d', 'propstat'))
+        prop = ET.SubElement(propstat, _qn('d', 'prop'))
+        rt = ET.SubElement(prop, _qn('d', 'resourcetype'))
+        ET.SubElement(rt, _qn('d', 'collection'))
+        ET.SubElement(prop, _qn('d', 'displayname')).text = 'Adressbücher'
+        ET.SubElement(propstat, _qn('d', 'status')).text = 'HTTP/1.1 200 OK'
+        multistatus.append(container)
+        if depth != '0':
+            for ab in _user_addressbooks(user):
+                multistatus.append(_addressbook_response(user, ab))
+        return _xml_response(multistatus)
+
+    # /dav/<username>/cal-<id>/ : calendar + events  (auch tl-N delegieren)
+    if len(parts) == 2:
+        if parts[0] != user.username:
+            return Response('', 403)
+        if parts[1].startswith('tl-'):
+            from .taskdav import tl_propfind
+            return tl_propfind(username=parts[0], tl_part=parts[1])
+        cal_id = _parse_calendar_path(parts[1])
+        if cal_id is None:
+            return Response('Not found', 404)
+        cal = _calendar_for(user, cal_id)
+        if not cal:
+            return Response('Not found', 404)
+        multistatus.append(_calendar_response(user, cal))
+        if depth != '0':
+            for ev in CalendarEvent.query.filter_by(calendar_id=cal.id).all():
+                multistatus.append(_event_response(user, cal, ev))
+        return _xml_response(multistatus)
+
+    # /dav/<username>/cal-<id>/<uid>.ics : single event  (tl-N delegieren)
+    if len(parts) == 3:
+        if parts[0] != user.username:
+            return Response('', 403)
+        if parts[1].startswith('tl-'):
+            from .taskdav import tl_task_propfind
+            return tl_task_propfind(username=parts[0], tl_part=parts[1], filename=parts[2])
+        cal_id = _parse_calendar_path(parts[1])
+        cal = _calendar_for(user, cal_id) if cal_id else None
+        if not cal:
+            return Response('Not found', 404)
+        uid = parts[2].removesuffix('.ics')
+        ev = CalendarEvent.query.filter_by(calendar_id=cal.id, uid=uid).first()
+        if not ev:
+            return Response('Not found', 404)
+        multistatus.append(_event_response(user, cal, ev, include_data=True))
+        return _xml_response(multistatus)
+
+    return Response('Not found', 404)
+
+
+# ---------------------------------------------------------------------------
+# REPORT (calendar-query, calendar-multiget)
+# ---------------------------------------------------------------------------
+
+@dav_bp.route('/<path:subpath>', methods=['REPORT'])
+@basic_auth
+def report(subpath):
+    user: User = request.dav_user
+    parts = [p for p in subpath.split('/') if p]
+    if len(parts) < 2 or parts[0] != user.username:
+        return Response('', 403)
+    if parts[1].startswith('tl-'):
+        from .taskdav import tl_report
+        return tl_report(username=parts[0], tl_part=parts[1])
+    cal_id = _parse_calendar_path(parts[1])
+    cal = _calendar_for(user, cal_id) if cal_id else None
+    if not cal:
+        return Response('Not found', 404)
+
+    try:
+        root = ET.fromstring(request.data or b'<x/>')
+    except ET.ParseError:
+        return Response('Malformed XML', 400)
+
+    multistatus = ET.Element(_qn('d', 'multistatus'))
+    tag = root.tag
+
+    # Prüfen ob der Client calendar-data angefragt hat. Falls nicht,
+    # liefern wir es auch nicht mit - strikter nach RFC und DAVx5
+    # entscheidet dann sauber "ich brauche Phase 2: multiget".
+    wants_data = root.find(f".//{_qn('c', 'calendar-data')}") is not None
+
+    if tag == _qn('c', 'calendar-multiget'):
+        hrefs = [h.text for h in root.findall(_qn('d', 'href')) if h.text]
+        for href in hrefs:
+            uid = href.rsplit('/', 1)[-1].removesuffix('.ics')
+            ev = CalendarEvent.query.filter_by(calendar_id=cal.id, uid=uid).first()
+            if ev:
+                multistatus.append(_event_response(user, cal, ev, include_data=True))
+        return _xml_response(multistatus)
+
+    if tag == _qn('c', 'calendar-query'):
+        start, end = _extract_time_range(root)
+        q = CalendarEvent.query.filter_by(calendar_id=cal.id)
+        if end is not None:
+            q = q.filter(CalendarEvent.dtstart < end)
+        if start is not None:
+            q = q.filter(
+                (CalendarEvent.dtend >= start) | (CalendarEvent.dtstart >= start)
+                | (CalendarEvent.recurrence_rule.isnot(None))
+            )
+        for ev in q.all():
+            multistatus.append(_event_response(user, cal, ev, include_data=wants_data))
+        return _xml_response(multistatus)
+
+    # Unknown report - return empty multistatus so clients don't break
+    return _xml_response(multistatus)
+
+
+def _extract_time_range(root: ET.Element):
+    tr = root.find(f".//{_qn('c', 'time-range')}")
+    if tr is None:
+        return None, None
+    def parse(s):
+        if not s:
+            return None
+        s = s.replace('Z', '+00:00')
+        dt = None
+        try:
+            dt = datetime.fromisoformat(s)
+        except ValueError:
+            try:
+                dt = datetime.strptime(s, '%Y%m%dT%H%M%S%z')
+            except ValueError:
+                try:
+                    dt = datetime.strptime(s[:15], '%Y%m%dT%H%M%S').replace(tzinfo=timezone.utc)
+                except ValueError:
+                    return None
+        # Unsere DB-Spalten sind tz-naive (lokal UTC) - Vergleich ginge
+        # sonst mit TypeError. Also tz-Info abstreifen.
+        if dt.tzinfo is not None:
+            dt = dt.astimezone(timezone.utc).replace(tzinfo=None)
+        return dt
+    return parse(tr.get('start')), parse(tr.get('end'))
+
+
+# ---------------------------------------------------------------------------
+# GET single event
+# ---------------------------------------------------------------------------
+
+@dav_bp.route('/<username>/<cal_part>/<filename>', methods=['GET', 'HEAD'])
+@basic_auth
+def get_event(username, cal_part, filename):
+    if cal_part.startswith('ab-'):
+        from .carddav import ab_get
+        return ab_get(username=username, ab_part=cal_part, filename=filename)
+    if cal_part.startswith('tl-'):
+        from .taskdav import tl_get
+        return tl_get(username=username, tl_part=cal_part, filename=filename)
+    user: User = request.dav_user
+    if username != user.username:
+        return Response('', 403)
+    cal_id = _parse_calendar_path(cal_part)
+    cal = _calendar_for(user, cal_id) if cal_id else None
+    if not cal:
+        return Response('Not found', 404)
+    uid = filename.removesuffix('.ics')
+    ev = CalendarEvent.query.filter_by(calendar_id=cal.id, uid=uid).first()
+    if not ev:
+        return Response('Not found', 404)
+    return Response(
+        _wrap_vcalendar(cal, ev),
+        mimetype='text/calendar; charset=utf-8',
+        headers={'ETag': _etag_for_event(ev)},
+    )
+
+
+# ---------------------------------------------------------------------------
+# PUT event (create or update)
+# ---------------------------------------------------------------------------
+
+@dav_bp.route('/<username>/<cal_part>/<filename>', methods=['PUT'])
+@basic_auth
+def put_event(username, cal_part, filename):
+    if cal_part.startswith('ab-'):
+        from .carddav import ab_put
+        return ab_put(username=username, ab_part=cal_part, filename=filename)
+    if cal_part.startswith('tl-'):
+        from .taskdav import tl_put
+        return tl_put(username=username, tl_part=cal_part, filename=filename)
+    user: User = request.dav_user
+    if username != user.username:
+        return Response('', 403)
+    cal_id = _parse_calendar_path(cal_part)
+    cal = _calendar_for(user, cal_id) if cal_id else None
+    if not cal:
+        return Response('Not found', 404)
+
+    uid = filename.removesuffix('.ics')
+    raw = request.get_data(as_text=True) or ''
+    parsed = _parse_vevent(raw)
+    if not parsed:
+        return Response('Cannot parse VEVENT', 400)
+
+    # UID inside the body wins over the filename if present
+    body_uid = parsed.get('uid') or uid
+
+    existing = CalendarEvent.query.filter_by(calendar_id=cal.id, uid=body_uid).first()
+    if_match = request.headers.get('If-Match')
+    if_none_match = request.headers.get('If-None-Match')
+
+    if existing and if_none_match == '*':
+        return Response('', 412)
+    if if_match and existing and if_match.strip() != _etag_for_event(existing):
+        return Response('', 412)
+
+    if not existing:
+        existing = CalendarEvent(calendar_id=cal.id, uid=body_uid, ical_data=raw)
+        db.session.add(existing)
+
+    existing.summary = parsed.get('summary') or '(ohne Titel)'
+    existing.description = parsed.get('description')
+    existing.location = parsed.get('location')
+    existing.dtstart = parsed.get('dtstart')
+    existing.dtend = parsed.get('dtend')
+    existing.all_day = parsed.get('all_day', False)
+    existing.recurrence_rule = parsed.get('rrule')
+    existing.exdates = ','.join(parsed.get('exdates', [])) or None
+    # Keep the raw VEVENT as-is so CalDAV clients round-trip faithfully.
+    existing.ical_data = _extract_vevent_block(raw)
+    existing.updated_at = datetime.now(timezone.utc)
+    db.session.commit()
+    notify_calendar_change(cal.owner_id, cal.id, 'event',
+                           shared_with=_cal_recipients(cal))
+
+    status = 201 if request.method == 'PUT' and not if_match else 204
+    return Response('', status, {'ETag': _etag_for_event(existing)})
+
+
+# ---------------------------------------------------------------------------
+# DELETE
+# ---------------------------------------------------------------------------
+
+@dav_bp.route('/<username>/<cal_part>/<filename>', methods=['DELETE'])
+@basic_auth
+def delete_event(username, cal_part, filename):
+    if cal_part.startswith('ab-'):
+        from .carddav import ab_delete
+        return ab_delete(username=username, ab_part=cal_part, filename=filename)
+    if cal_part.startswith('tl-'):
+        from .taskdav import tl_delete
+        return tl_delete(username=username, tl_part=cal_part, filename=filename)
+    user: User = request.dav_user
+    if username != user.username:
+        return Response('', 403)
+    cal_id = _parse_calendar_path(cal_part)
+    cal = _calendar_for(user, cal_id) if cal_id else None
+    if not cal:
+        return Response('Not found', 404)
+    uid = filename.removesuffix('.ics')
+    ev = CalendarEvent.query.filter_by(calendar_id=cal.id, uid=uid).first()
+    if not ev:
+        return Response('', 404)
+    db.session.delete(ev)
+    db.session.commit()
+    notify_calendar_change(cal.owner_id, cal.id, 'event',
+                           shared_with=_cal_recipients(cal))
+    return Response('', 204)
+
+
+@dav_bp.route('/<username>/<cal_part>/', methods=['DELETE'])
+@dav_bp.route('/<username>/<cal_part>', methods=['DELETE'])
+@basic_auth
+def delete_calendar(username, cal_part):
+    if cal_part.startswith('ab-'):
+        from .carddav import ab_delete_collection
+        return ab_delete_collection(username=username, ab_part=cal_part)
+    if cal_part.startswith('tl-'):
+        from .taskdav import tl_delete_collection
+        return tl_delete_collection(username=username, tl_part=cal_part)
+    user: User = request.dav_user
+    if username != user.username:
+        return Response('', 403)
+    cal_id = _parse_calendar_path(cal_part)
+    cal = _calendar_for(user, cal_id) if cal_id else None
+    if not cal:
+        return Response('', 404)
+    recipients = _cal_recipients(cal)
+    owner_id = cal.owner_id
+    cid = cal.id
+    db.session.delete(cal)
+    db.session.commit()
+    notify_calendar_change(owner_id, cid, 'deleted', shared_with=recipients)
+    return Response('', 204)
+
+
+# ---------------------------------------------------------------------------
+# PROPPATCH (Clients setzen gerne Anzeigefarbe/-name). Wir persistieren
+# den Kalenderfarbe (calendar-color) + Displayname; andere Properties
+# bestaetigen wir als "angewendet" damit DAVx5/Apple zufrieden sind.
+# ---------------------------------------------------------------------------
+
+@dav_bp.route('/<username>/<cal_part>/', methods=['PROPPATCH'])
+@dav_bp.route('/<username>/<cal_part>', methods=['PROPPATCH'])
+@basic_auth
+def proppatch_calendar(username, cal_part):
+    if cal_part.startswith('tl-'):
+        from .taskdav import tl_proppatch
+        return tl_proppatch(username=username, tl_part=cal_part)
+    user: User = request.dav_user
+    if username != user.username:
+        return Response('', 403)
+    cal_id = _parse_calendar_path(cal_part)
+    cal = _calendar_for(user, cal_id) if cal_id else None
+    if not cal:
+        return Response('Not found', 404)
+    try:
+        root = ET.fromstring(request.data or b'<x/>')
+    except ET.ParseError:
+        return Response('Malformed XML', 400)
+
+    for el in root.iter():
+        tag = el.tag
+        if tag == _qn('ic', 'calendar-color') and el.text:
+            cal.color = el.text.strip()[:7]
+        elif tag == _qn('d', 'displayname') and el.text:
+            cal.name = el.text.strip()[:255]
+    db.session.commit()
+
+    # Respond with 207 marking everything as applied so the client is happy.
+    multistatus = ET.Element(_qn('d', 'multistatus'))
+    href = _href_calendar(user.username, cal.id)
+    resp = ET.SubElement(multistatus, _qn('d', 'response'))
+    ET.SubElement(resp, _qn('d', 'href')).text = href
+    propstat = ET.SubElement(resp, _qn('d', 'propstat'))
+    prop = ET.SubElement(propstat, _qn('d', 'prop'))
+    # Echo back everything the client asked to set
+    for set_block in root.findall(_qn('d', 'set')):
+        inner_prop = set_block.find(_qn('d', 'prop'))
+        if inner_prop is not None:
+            for child in inner_prop:
+                ET.SubElement(prop, child.tag)
+    ET.SubElement(propstat, _qn('d', 'status')).text = 'HTTP/1.1 200 OK'
+    return _xml_response(multistatus)
+
+
+# ---------------------------------------------------------------------------
+# MKCALENDAR (create a new calendar collection via the DAV URL)
+# ---------------------------------------------------------------------------
+
+@dav_bp.route('/<username>/<cal_part>/', methods=['MKCALENDAR'])
+@dav_bp.route('/<username>/<cal_part>', methods=['MKCALENDAR'])
+@basic_auth
+def mkcalendar(username, cal_part):
+    user: User = request.dav_user
+    if username != user.username:
+        return Response('', 403)
+
+    # Extract display name from body if present
+    name = 'Neuer Kalender'
+    color = '#3788d8'
+    try:
+        body = request.get_data()
+        if body:
+            root = ET.fromstring(body)
+            dn = root.find(f".//{_qn('d', 'displayname')}")
+            if dn is not None and dn.text:
+                name = dn.text
+            col = root.find(f".//{_qn('ic', 'calendar-color')}")
+            if col is not None and col.text:
+                color = col.text[:7]
+    except ET.ParseError:
+        pass
+
+    cal = Calendar(owner_id=user.id, name=name, color=color)
+    db.session.add(cal)
+    db.session.commit()
+    return Response('', 201, {'Location': _href_calendar(user.username, cal.id)})
+
+
+# ---------------------------------------------------------------------------
+# VEVENT parser (quick & pragmatic - covers what the major CalDAV clients send)
+# ---------------------------------------------------------------------------
+
+def _extract_vevent_block(raw: str) -> str:
+    """Return only the VEVENT block from a full VCALENDAR body. If none
+    is found the input is returned as-is."""
+    m = re.search(r'BEGIN:VEVENT[\s\S]*?END:VEVENT', raw, flags=re.IGNORECASE)
+    return m.group(0) if m else raw
+
+
+def _unfold(raw: str) -> list[str]:
+    """Undo RFC 5545 line folding (continuation lines start with space/tab)."""
+    lines = []
+    for line in raw.replace('\r\n', '\n').split('\n'):
+        if line.startswith((' ', '\t')) and lines:
+            lines[-1] += line[1:]
+        else:
+            lines.append(line)
+    return lines
+
+
+def _parse_dt(value: str, params: dict) -> tuple[datetime | None, bool]:
+    """Parse an iCalendar DATE or DATE-TIME. Returns (datetime, all_day)."""
+    if not value:
+        return None, False
+    is_date = params.get('VALUE', '').upper() == 'DATE' or len(value) == 8
+    if is_date:
+        try:
+            return datetime.strptime(value, '%Y%m%d'), True
+        except ValueError:
+            return None, True
+    # Try Z (UTC), TZID-tagged, or naive floating time
+    val = value.replace('Z', '')
+    for fmt in ('%Y%m%dT%H%M%S', '%Y-%m-%dT%H:%M:%S', '%Y-%m-%d %H:%M:%S'):
+        try:
+            dt = datetime.strptime(val, fmt)
+            if value.endswith('Z'):
+                dt = dt.replace(tzinfo=timezone.utc)
+            return dt, False
+        except ValueError:
+            continue
+    return None, False
+
+
+def _parse_vevent(raw: str) -> dict | None:
+    block = _extract_vevent_block(raw)
+    if 'BEGIN:VEVENT' not in block.upper():
+        return None
+    result: dict = {'exdates': []}
+    for line in _unfold(block):
+        if ':' not in line:
+            continue
+        key, _, value = line.partition(':')
+        # Separate parameters: "DTSTART;TZID=Europe/Berlin"
+        parts = key.split(';')
+        name = parts[0].upper()
+        params = {}
+        for p in parts[1:]:
+            if '=' in p:
+                k, v = p.split('=', 1)
+                params[k.upper()] = v
+
+        if name == 'UID':
+            result['uid'] = value.strip()
+        elif name == 'SUMMARY':
+            result['summary'] = _unescape(value)
+        elif name == 'DESCRIPTION':
+            result['description'] = _unescape(value)
+        elif name == 'LOCATION':
+            result['location'] = _unescape(value)
+        elif name == 'DTSTART':
+            dt, all_day = _parse_dt(value, params)
+            result['dtstart'] = dt
+            result['all_day'] = all_day
+        elif name == 'DTEND':
+            dt, _ = _parse_dt(value, params)
+            result['dtend'] = dt
+        elif name == 'RRULE':
+            result['rrule'] = value.strip()
+        elif name == 'EXDATE':
+            dt, all_day = _parse_dt(value, params)
+            if dt:
+                result['exdates'].append(
+                    dt.strftime('%Y-%m-%d' if all_day else '%Y-%m-%dT%H:%M:%S')
+                )
+    if 'uid' not in result:
+        result['uid'] = str(uuid.uuid4())
+    return result
+
+
+def _unescape(s: str) -> str:
+    return s.replace('\\n', '\n').replace('\\,', ',').replace('\\;', ';').replace('\\\\', '\\')

backend/app/dav/carddav.py

@@ -0,0 +1,367 @@
+"""Minimal CardDAV server (RFC 6352 subset).
+
+Mirror structure of caldav.py - adds addressbook collections under
+  /dav/<username>/ab-<id>/
+and serves vCard 3.0 resources via GET/PUT/DELETE plus addressbook-query
+and addressbook-multiget REPORTs.
+
+Reuses the auth + XML helpers from caldav.py to stay consistent.
+"""
+from __future__ import annotations
+
+import re
+import uuid
+import xml.etree.ElementTree as ET
+from datetime import datetime, timezone
+
+from flask import Response, request
+
+from app.extensions import db
+from app.models.contact import AddressBook, Contact, AddressBookShare
+from app.models.user import User
+from app.api.contacts import (
+    _apply_fields_to_contact, _build_vcard, parse_vcard,
+    _notify_addressbook, _book_recipients,
+)
+
+from . import dav_bp
+from .caldav import (
+    NS, _qn, _xml_response, basic_auth, _make_response,
+    _principal_response,  # reused - we extend below
+)
+
+
+# ---------------------------------------------------------------------------
+# URL helpers
+# ---------------------------------------------------------------------------
+
+def _href_addressbook(username: str, book_id: int) -> str:
+    return f'/dav/{username}/ab-{book_id}/'
+
+
+def _href_vcard(username: str, book_id: int, uid: str) -> str:
+    return f'/dav/{username}/ab-{book_id}/{uid}.vcf'
+
+
+def _parse_addressbook_path(part: str):
+    m = re.match(r'ab-(\d+)$', part)
+    return int(m.group(1)) if m else None
+
+
+def _user_addressbooks(user: User):
+    return AddressBook.query.filter_by(owner_id=user.id).all()
+
+
+def _addressbook_for(user: User, book_id: int):
+    book = db.session.get(AddressBook, book_id)
+    if not book or book.owner_id != user.id:
+        return None
+    return book
+
+
+# ---------------------------------------------------------------------------
+# Property responses
+# ---------------------------------------------------------------------------
+
+def _addressbook_ctag(book: AddressBook) -> str:
+    last = db.session.query(db.func.max(Contact.updated_at)).filter_by(address_book_id=book.id).scalar()
+    ts = int((last or book.updated_at or datetime.now(timezone.utc)).timestamp())
+    return f'"ab{book.id}-{ts}"'
+
+
+def _addressbook_response(user: User, book: AddressBook) -> ET.Element:
+    href = _href_addressbook(user.username, book.id)
+
+    def populate(prop):
+        rt = ET.SubElement(prop, _qn('d', 'resourcetype'))
+        ET.SubElement(rt, _qn('d', 'collection'))
+        # urn:ietf:params:xml:ns:carddav addressbook element
+        ab = ET.SubElement(rt, '{urn:ietf:params:xml:ns:carddav}addressbook')  # noqa: F841
+        ET.SubElement(prop, _qn('d', 'displayname')).text = book.name
+        ET.SubElement(prop, '{urn:ietf:params:xml:ns:carddav}addressbook-description').text = book.description or ''
+        srs = ET.SubElement(prop, _qn('d', 'supported-report-set'))
+        for r in ('addressbook-query', 'addressbook-multiget'):
+            sup = ET.SubElement(srs, _qn('d', 'supported-report'))
+            rep = ET.SubElement(sup, _qn('d', 'report'))
+            ET.SubElement(rep, '{urn:ietf:params:xml:ns:carddav}' + r)
+        ET.SubElement(prop, _qn('ic', 'calendar-color')).text = book.color or '#3788d8'
+        ET.SubElement(prop, _qn('cs', 'getctag')).text = _addressbook_ctag(book)
+        cups = ET.SubElement(prop, _qn('d', 'current-user-privilege-set'))
+        for priv in ('read', 'write', 'write-properties', 'write-content', 'bind', 'unbind'):
+            p = ET.SubElement(cups, _qn('d', 'privilege'))
+            ET.SubElement(p, _qn('d', priv))
+    return _make_response(href, populate)
+
+
+def _vcard_response(user: User, book: AddressBook, contact: Contact, include_data: bool = False) -> ET.Element:
+    href = _href_vcard(user.username, book.id, contact.uid)
+
+    def populate(prop):
+        ts = int((contact.updated_at or datetime.now(timezone.utc)).timestamp() * 1000)
+        ET.SubElement(prop, _qn('d', 'getetag')).text = f'"{contact.id}-{ts}"'
+        ET.SubElement(prop, _qn('d', 'getcontenttype')).text = 'text/vcard; charset=utf-8'
+        ET.SubElement(prop, _qn('d', 'resourcetype'))
+        if include_data:
+            ET.SubElement(prop, '{urn:ietf:params:xml:ns:carddav}address-data').text = \
+                contact.vcard_data or _build_vcard(contact)
+    return _make_response(href, populate)
+
+
+def _etag_for_contact(contact: Contact) -> str:
+    ts = int((contact.updated_at or contact.created_at or datetime.now(timezone.utc)).timestamp() * 1000)
+    return f'"{contact.id}-{ts}"'
+
+
+# ---------------------------------------------------------------------------
+# Extend the principal response from caldav.py to include addressbook-home-set
+# This is done by wrapping the existing helper and appending the extra prop.
+# ---------------------------------------------------------------------------
+
+# We import caldav.propfind and add a separate URL-rule set here. For the
+# principal, caldav._principal_response already emits calendar-home-set; we
+# leave the combined principal to that function. CardDAV clients that check
+# addressbook-home-set via PROPFIND get it via our own route below, because
+# the URL `/dav/<username>/` is handled by caldav's propfind. To also return
+# addressbook-home-set there we monkey-patch the principal populate.
+
+# Simpler approach: re-implement the principal for our own URL-space by
+# hooking into the propfind dispatcher's principal branch.
+
+# Since caldav.propfind already builds the principal response, we inject the
+# addressbook-home-set via a wrapper. Let's override by providing our own
+# handler in the blueprint that augments the response.
+
+
+# ---------------------------------------------------------------------------
+# OPTIONS / PROPFIND / REPORT / GET / PUT / DELETE for /dav/<user>/ab-<id>/...
+# ---------------------------------------------------------------------------
+
+_DAV_HEADERS = {'DAV': '1, 2, 3, addressbook'}
+
+
+@dav_bp.route('/<username>/<ab_part>/', methods=['OPTIONS'])
+@dav_bp.route('/<username>/<ab_part>', methods=['OPTIONS'])
+def ab_options(username, ab_part):
+    if not ab_part.startswith('ab-'):
+        from .caldav import options as _cal_options
+        return _cal_options(subpath=f'{username}/{ab_part}')
+    return Response('', 200, {
+        'DAV': '1, 2, 3, addressbook',
+        'Allow': 'OPTIONS, PROPFIND, REPORT, GET, PUT, DELETE, PROPPATCH, MKCOL',
+    })
+
+
+@dav_bp.route('/<username>/<ab_part>/', methods=['PROPFIND'])
+@dav_bp.route('/<username>/<ab_part>', methods=['PROPFIND'])
+@basic_auth
+def ab_propfind(username, ab_part):
+    if not ab_part.startswith('ab-'):
+        from .caldav import propfind as _cal_propfind
+        return _cal_propfind(subpath=f'{username}/{ab_part}')
+    user: User = request.dav_user
+    if username != user.username:
+        return Response('', 403)
+    book_id = _parse_addressbook_path(ab_part)
+    book = _addressbook_for(user, book_id) if book_id else None
+    if not book:
+        return Response('Not found', 404)
+
+    depth = request.headers.get('Depth', '0')
+    multistatus = ET.Element(_qn('d', 'multistatus'))
+    multistatus.append(_addressbook_response(user, book))
+    if depth != '0':
+        for c in book.contacts.all():
+            multistatus.append(_vcard_response(user, book, c))
+    return _xml_response(multistatus)
+
+
+@dav_bp.route('/<username>/<ab_part>/<filename>', methods=['PROPFIND'])
+@basic_auth
+def ab_contact_propfind(username, ab_part, filename):
+    user: User = request.dav_user
+    if username != user.username:
+        return Response('', 403)
+    book_id = _parse_addressbook_path(ab_part)
+    book = _addressbook_for(user, book_id) if book_id else None
+    if not book:
+        return Response('Not found', 404)
+    uid = filename.removesuffix('.vcf')
+    contact = Contact.query.filter_by(address_book_id=book.id, uid=uid).first()
+    if not contact:
+        return Response('Not found', 404)
+    multistatus = ET.Element(_qn('d', 'multistatus'))
+    multistatus.append(_vcard_response(user, book, contact, include_data=True))
+    return _xml_response(multistatus)
+
+
+@dav_bp.route('/<username>/<ab_part>/', methods=['REPORT'])
+@dav_bp.route('/<username>/<ab_part>', methods=['REPORT'])
+@basic_auth
+def ab_report(username, ab_part):
+    if not ab_part.startswith('ab-'):
+        from .caldav import report as _cal_report
+        return _cal_report(subpath=f'{username}/{ab_part}')
+    user: User = request.dav_user
+    if username != user.username:
+        return Response('', 403)
+    book_id = _parse_addressbook_path(ab_part)
+    book = _addressbook_for(user, book_id) if book_id else None
+    if not book:
+        return Response('Not found', 404)
+
+    try:
+        root = ET.fromstring(request.data or b'<x/>')
+    except ET.ParseError:
+        return Response('Malformed XML', 400)
+
+    wants_data = root.find(f".//{{urn:ietf:params:xml:ns:carddav}}address-data") is not None
+    multistatus = ET.Element(_qn('d', 'multistatus'))
+
+    if root.tag == '{urn:ietf:params:xml:ns:carddav}addressbook-multiget':
+        hrefs = [h.text for h in root.findall(_qn('d', 'href')) if h.text]
+        for href in hrefs:
+            uid = href.rsplit('/', 1)[-1].removesuffix('.vcf')
+            contact = Contact.query.filter_by(address_book_id=book.id, uid=uid).first()
+            if contact:
+                multistatus.append(_vcard_response(user, book, contact, include_data=True))
+        return _xml_response(multistatus)
+
+    if root.tag == '{urn:ietf:params:xml:ns:carddav}addressbook-query':
+        # No filter implementation yet - return all
+        for contact in book.contacts.all():
+            multistatus.append(_vcard_response(user, book, contact, include_data=wants_data))
+        return _xml_response(multistatus)
+
+    return _xml_response(multistatus)
+
+
+@dav_bp.route('/<username>/<ab_part>/<filename>', methods=['GET', 'HEAD'])
+@basic_auth
+def ab_get(username, ab_part, filename):
+    user: User = request.dav_user
+    if username != user.username:
+        return Response('', 403)
+    book_id = _parse_addressbook_path(ab_part)
+    book = _addressbook_for(user, book_id) if book_id else None
+    if not book:
+        return Response('Not found', 404)
+    uid = filename.removesuffix('.vcf')
+    contact = Contact.query.filter_by(address_book_id=book.id, uid=uid).first()
+    if not contact:
+        return Response('Not found', 404)
+    return Response(
+        contact.vcard_data or _build_vcard(contact),
+        mimetype='text/vcard; charset=utf-8',
+        headers={'ETag': _etag_for_contact(contact)},
+    )
+
+
+@dav_bp.route('/<username>/<ab_part>/<filename>', methods=['PUT'])
+@basic_auth
+def ab_put(username, ab_part, filename):
+    user: User = request.dav_user
+    if username != user.username:
+        return Response('', 403)
+    book_id = _parse_addressbook_path(ab_part)
+    book = _addressbook_for(user, book_id) if book_id else None
+    if not book:
+        return Response('Not found', 404)
+
+    uid = filename.removesuffix('.vcf')
+    raw = request.get_data(as_text=True) or ''
+    parsed = parse_vcard(raw)
+    body_uid = parsed.get('uid') or uid
+
+    existing = Contact.query.filter_by(address_book_id=book.id, uid=body_uid).first()
+    if_match = request.headers.get('If-Match')
+    if_none_match = request.headers.get('If-None-Match')
+    if existing and if_none_match == '*':
+        return Response('', 412)
+    if if_match and existing and if_match.strip() != _etag_for_contact(existing):
+        return Response('', 412)
+
+    is_new = existing is None
+    if is_new:
+        existing = Contact(address_book_id=book.id, uid=body_uid, vcard_data=raw)
+        db.session.add(existing)
+
+    _apply_fields_to_contact(existing, parsed)
+    # Keep the original raw VCARD so round-tripping is faithful - but also
+    # record the server-rebuilt version for web UI consumers. We prefer the
+    # raw source of truth here.
+    existing.vcard_data = raw.strip() or _build_vcard(existing)
+    existing.updated_at = datetime.now(timezone.utc)
+    db.session.commit()
+    _notify_addressbook(book.owner_id, book.id, 'contact',
+                        shared_with=_book_recipients(book))
+    status = 201 if is_new else 204
+    return Response('', status, {'ETag': _etag_for_contact(existing)})
+
+
+@dav_bp.route('/<username>/<ab_part>/<filename>', methods=['DELETE'])
+@basic_auth
+def ab_delete(username, ab_part, filename):
+    user: User = request.dav_user
+    if username != user.username:
+        return Response('', 403)
+    book_id = _parse_addressbook_path(ab_part)
+    book = _addressbook_for(user, book_id) if book_id else None
+    if not book:
+        return Response('Not found', 404)
+    uid = filename.removesuffix('.vcf')
+    contact = Contact.query.filter_by(address_book_id=book.id, uid=uid).first()
+    if not contact:
+        return Response('', 404)
+    db.session.delete(contact)
+    db.session.commit()
+    _notify_addressbook(book.owner_id, book.id, 'contact',
+                        shared_with=_book_recipients(book))
+    return Response('', 204)
+
+
+@dav_bp.route('/<username>/<ab_part>/', methods=['DELETE'])
+@dav_bp.route('/<username>/<ab_part>', methods=['DELETE'])
+@basic_auth
+def ab_delete_collection(username, ab_part):
+    if not ab_part.startswith('ab-'):
+        return Response('', 404)
+    user: User = request.dav_user
+    if username != user.username:
+        return Response('', 403)
+    book_id = _parse_addressbook_path(ab_part)
+    book = _addressbook_for(user, book_id) if book_id else None
+    if not book:
+        return Response('', 404)
+    recipients = _book_recipients(book)
+    owner_id = book.owner_id
+    book_id = book.id
+    db.session.delete(book)
+    db.session.commit()
+    _notify_addressbook(owner_id, book_id, 'deleted', shared_with=recipients)
+    return Response('', 204)
+
+
+@dav_bp.route('/<username>/<ab_part>/', methods=['MKCOL'])
+@dav_bp.route('/<username>/<ab_part>', methods=['MKCOL'])
+@basic_auth
+def ab_mkcol(username, ab_part):
+    """Create a new addressbook collection via MKCOL (RFC 5689 extended).
+    Some CardDAV clients (Apple) use this instead of MKCALENDAR."""
+    user: User = request.dav_user
+    if username != user.username:
+        return Response('', 403)
+    name = 'Neues Adressbuch'
+    try:
+        body = request.get_data()
+        if body:
+            root = ET.fromstring(body)
+            dn = root.find(f".//{_qn('d', 'displayname')}")
+            if dn is not None and dn.text:
+                name = dn.text
+    except ET.ParseError:
+        pass
+    book = AddressBook(owner_id=user.id, name=name)
+    db.session.add(book)
+    db.session.commit()
+    _notify_addressbook(user.id, book.id, 'created')
+    return Response('', 201, {'Location': _href_addressbook(user.username, book.id)})

backend/app/dav/taskdav.py

@@ -0,0 +1,368 @@
+"""CalDAV Task-List Handler (VTODO).
+
+TaskLists werden parallel zu Calendars als Calendar-Collection
+ausgeliefert, jedoch mit `<supported-calendar-component-set>` = VTODO
+(statt VEVENT). DAVx5/OpenTasks erkennen sie dadurch automatisch als
+Aufgabenliste.
+
+URL-Schema:
+  /dav/<user>/tl-<id>/                    Collection
+  /dav/<user>/tl-<id>/<uid>.ics           VTODO-Resource
+
+Diese Funktionen werden aus caldav.py heraus aufgerufen, sobald der
+URL-Bestandteil mit `tl-` beginnt - parallel zur ab-/CardDAV-Delegation.
+"""
+from __future__ import annotations
+
+import re
+import xml.etree.ElementTree as ET
+from datetime import datetime, timezone
+
+from flask import Response, request
+
+from app.extensions import db
+from app.models.task import TaskList, Task
+from app.models.user import User
+from app.api.tasks import build_vtodo, parse_vtodo, _list_recipients
+from app.services.events import notify_tasklist_change
+
+
+# Re-use XML helpers from caldav.py
+def _import_caldav_helpers():
+    from . import caldav
+    return caldav
+
+
+def _qn(prefix, name):
+    return _import_caldav_helpers()._qn(prefix, name)
+
+
+def _xml_response(elem):
+    return _import_caldav_helpers()._xml_response(elem)
+
+
+def _make_response(href, populate):
+    return _import_caldav_helpers()._make_response(href, populate)
+
+
+# ---------------------------------------------------------------------------
+# Path / URL helpers
+# ---------------------------------------------------------------------------
+
+def parse_tl_path(part: str):
+    m = re.match(r'tl-(\d+)$', part)
+    return int(m.group(1)) if m else None
+
+
+def href_list(username, lid):
+    return f'/dav/{username}/tl-{lid}/'
+
+
+def href_task(username, lid, uid):
+    return f'/dav/{username}/tl-{lid}/{uid}.ics'
+
+
+def user_lists(user: User):
+    return TaskList.query.filter_by(owner_id=user.id).all()
+
+
+def list_for(user: User, lid: int):
+    tl = db.session.get(TaskList, lid)
+    if not tl or tl.owner_id != user.id:
+        return None
+    return tl
+
+
+def _ctag(tl: TaskList) -> str:
+    last = db.session.query(db.func.max(Task.updated_at)).filter_by(task_list_id=tl.id).scalar()
+    ts = int((last or tl.updated_at or datetime.now(timezone.utc)).timestamp())
+    return f'"tl{tl.id}-{ts}"'
+
+
+def _etag(t: Task) -> str:
+    ts = int((t.updated_at or t.created_at or datetime.now(timezone.utc)).timestamp() * 1000)
+    return f'"{t.id}-{ts}"'
+
+
+def _wrap_vcalendar(t: Task) -> str:
+    block = (t.ical_data or '').strip() or build_vtodo(t)
+    return '\r\n'.join([
+        'BEGIN:VCALENDAR', 'VERSION:2.0', 'PRODID:-//Mini-Cloud//DE',
+        'CALSCALE:GREGORIAN', block, 'END:VCALENDAR',
+    ])
+
+
+# ---------------------------------------------------------------------------
+# PROPFIND building blocks
+# ---------------------------------------------------------------------------
+
+def list_response(user: User, tl: TaskList) -> ET.Element:
+    href = href_list(user.username, tl.id)
+
+    def populate(prop):
+        rt = ET.SubElement(prop, _qn('d', 'resourcetype'))
+        ET.SubElement(rt, _qn('d', 'collection'))
+        ET.SubElement(rt, _qn('c', 'calendar'))
+        ET.SubElement(prop, _qn('d', 'displayname')).text = tl.name
+        ET.SubElement(prop, _qn('c', 'calendar-description')).text = tl.description or ''
+        supported = ET.SubElement(prop, _qn('c', 'supported-calendar-component-set'))
+        comp = ET.SubElement(supported, _qn('c', 'comp'))
+        comp.set('name', 'VTODO')
+        srs = ET.SubElement(prop, _qn('d', 'supported-report-set'))
+        for r in ('calendar-query', 'calendar-multiget'):
+            sup = ET.SubElement(srs, _qn('d', 'supported-report'))
+            rep = ET.SubElement(sup, _qn('d', 'report'))
+            ET.SubElement(rep, _qn('c', r))
+        ET.SubElement(prop, _qn('ic', 'calendar-color')).text = tl.color or '#10b981'
+        ET.SubElement(prop, _qn('cs', 'getctag')).text = _ctag(tl)
+        cups = ET.SubElement(prop, _qn('d', 'current-user-privilege-set'))
+        for priv in ('read', 'write', 'write-properties', 'write-content', 'bind', 'unbind'):
+            p = ET.SubElement(cups, _qn('d', 'privilege'))
+            ET.SubElement(p, _qn('d', priv))
+    return _make_response(href, populate)
+
+
+def task_response(user: User, tl: TaskList, t: Task, include_data=False) -> ET.Element:
+    href = href_task(user.username, tl.id, t.uid)
+
+    def populate(prop):
+        ET.SubElement(prop, _qn('d', 'getetag')).text = _etag(t)
+        ET.SubElement(prop, _qn('d', 'getcontenttype')).text = \
+            'text/calendar; charset=utf-8; component=VTODO'
+        ET.SubElement(prop, _qn('d', 'resourcetype'))
+        if include_data:
+            ET.SubElement(prop, _qn('c', 'calendar-data')).text = _wrap_vcalendar(t)
+    return _make_response(href, populate)
+
+
+# ---------------------------------------------------------------------------
+# Handlers (entered from caldav.py when path starts with tl-)
+# ---------------------------------------------------------------------------
+
+def tl_propfind(username, tl_part):
+    user: User = request.dav_user
+    if username != user.username:
+        return Response('', 403)
+    lid = parse_tl_path(tl_part)
+    tl = list_for(user, lid) if lid else None
+    if not tl:
+        return Response('Not found', 404)
+    depth = request.headers.get('Depth', '0')
+    multi = ET.Element(_qn('d', 'multistatus'))
+    multi.append(list_response(user, tl))
+    if depth != '0':
+        for t in tl.tasks.all():
+            multi.append(task_response(user, tl, t))
+    return _xml_response(multi)
+
+
+def tl_task_propfind(username, tl_part, filename):
+    user: User = request.dav_user
+    if username != user.username:
+        return Response('', 403)
+    lid = parse_tl_path(tl_part)
+    tl = list_for(user, lid) if lid else None
+    if not tl:
+        return Response('Not found', 404)
+    uid = filename.removesuffix('.ics')
+    t = Task.query.filter_by(task_list_id=tl.id, uid=uid).first()
+    if not t:
+        return Response('Not found', 404)
+    multi = ET.Element(_qn('d', 'multistatus'))
+    multi.append(task_response(user, tl, t, include_data=True))
+    return _xml_response(multi)
+
+
+def tl_report(username, tl_part):
+    user: User = request.dav_user
+    if username != user.username:
+        return Response('', 403)
+    lid = parse_tl_path(tl_part)
+    tl = list_for(user, lid) if lid else None
+    if not tl:
+        return Response('Not found', 404)
+    try:
+        root = ET.fromstring(request.data or b'<x/>')
+    except ET.ParseError:
+        return Response('Malformed XML', 400)
+    wants_data = root.find(f".//{_qn('c', 'calendar-data')}") is not None
+    multi = ET.Element(_qn('d', 'multistatus'))
+    if root.tag == _qn('c', 'calendar-multiget'):
+        hrefs = [h.text for h in root.findall(_qn('d', 'href')) if h.text]
+        for href in hrefs:
+            uid = href.rsplit('/', 1)[-1].removesuffix('.ics')
+            t = Task.query.filter_by(task_list_id=tl.id, uid=uid).first()
+            if t:
+                multi.append(task_response(user, tl, t, include_data=True))
+        return _xml_response(multi)
+    if root.tag == _qn('c', 'calendar-query'):
+        for t in tl.tasks.all():
+            multi.append(task_response(user, tl, t, include_data=wants_data))
+        return _xml_response(multi)
+    return _xml_response(multi)
+
+
+def tl_get(username, tl_part, filename):
+    user: User = request.dav_user
+    if username != user.username:
+        return Response('', 403)
+    lid = parse_tl_path(tl_part)
+    tl = list_for(user, lid) if lid else None
+    if not tl:
+        return Response('Not found', 404)
+    uid = filename.removesuffix('.ics')
+    t = Task.query.filter_by(task_list_id=tl.id, uid=uid).first()
+    if not t:
+        return Response('Not found', 404)
+    return Response(_wrap_vcalendar(t),
+                    mimetype='text/calendar; charset=utf-8',
+                    headers={'ETag': _etag(t)})
+
+
+def tl_put(username, tl_part, filename):
+    user: User = request.dav_user
+    if username != user.username:
+        return Response('', 403)
+    lid = parse_tl_path(tl_part)
+    tl = list_for(user, lid) if lid else None
+    if not tl:
+        return Response('Not found', 404)
+    uid = filename.removesuffix('.ics')
+    raw = request.get_data(as_text=True) or ''
+    parsed = parse_vtodo(raw)
+    if not parsed:
+        return Response('Cannot parse VTODO', 400)
+    body_uid = parsed.get('uid') or uid
+    existing = Task.query.filter_by(task_list_id=tl.id, uid=body_uid).first()
+    if_match = request.headers.get('If-Match')
+    if_none_match = request.headers.get('If-None-Match')
+    if existing and if_none_match == '*':
+        return Response('', 412)
+    if if_match and existing and if_match.strip() != _etag(existing):
+        return Response('', 412)
+    is_new = existing is None
+    if is_new:
+        existing = Task(task_list_id=tl.id, uid=body_uid, ical_data=raw)
+        db.session.add(existing)
+    existing.summary = parsed.get('summary') or '(ohne Titel)'
+    existing.description = parsed.get('description')
+    existing.status = parsed.get('status') or 'NEEDS-ACTION'
+    existing.priority = parsed.get('priority')
+    existing.percent_complete = parsed.get('percent_complete')
+    existing.due = parsed.get('due')
+    existing.dtstart = parsed.get('dtstart')
+    existing.completed_at = parsed.get('completed_at')
+    cats = parsed.get('categories')
+    if isinstance(cats, str):
+        existing.categories = cats or None
+    elif isinstance(cats, list):
+        existing.categories = ','.join(cats) or None
+    # Roh-Block sichern fuer Round-Trip
+    block = re.search(r'BEGIN:VTODO.*?END:VTODO', raw, flags=re.DOTALL | re.IGNORECASE)
+    existing.ical_data = (block.group(0).strip() if block else raw.strip()) or build_vtodo(existing)
+    existing.updated_at = datetime.now(timezone.utc)
+    db.session.commit()
+    notify_tasklist_change(tl.owner_id, tl.id, 'task', shared_with=_list_recipients(tl))
+    return Response('', 201 if is_new else 204, {'ETag': _etag(existing)})
+
+
+def tl_delete(username, tl_part, filename):
+    user: User = request.dav_user
+    if username != user.username:
+        return Response('', 403)
+    lid = parse_tl_path(tl_part)
+    tl = list_for(user, lid) if lid else None
+    if not tl:
+        return Response('Not found', 404)
+    uid = filename.removesuffix('.ics')
+    t = Task.query.filter_by(task_list_id=tl.id, uid=uid).first()
+    if not t:
+        return Response('', 404)
+    db.session.delete(t)
+    db.session.commit()
+    notify_tasklist_change(tl.owner_id, tl.id, 'task', shared_with=_list_recipients(tl))
+    return Response('', 204)
+
+
+def tl_delete_collection(username, tl_part):
+    user: User = request.dav_user
+    if username != user.username:
+        return Response('', 403)
+    lid = parse_tl_path(tl_part)
+    tl = list_for(user, lid) if lid else None
+    if not tl:
+        return Response('', 404)
+    recipients = _list_recipients(tl)
+    owner_id = tl.owner_id
+    list_id = tl.id
+    db.session.delete(tl)
+    db.session.commit()
+    notify_tasklist_change(owner_id, list_id, 'deleted', shared_with=recipients)
+    return Response('', 204)
+
+
+def tl_options(username, tl_part):
+    return Response('', 200, {
+        'DAV': '1, 2, 3, calendar-access, addressbook',
+        'Allow': 'OPTIONS, PROPFIND, REPORT, GET, PUT, DELETE, MKCALENDAR, PROPPATCH',
+    })
+
+
+def tl_proppatch(username, tl_part):
+    """Bestaetige Property-Updates damit Clients zufrieden sind. Wir
+    persistieren Displayname + Color, alles andere wird stillschweigend
+    akzeptiert."""
+    user: User = request.dav_user
+    if username != user.username:
+        return Response('', 403)
+    lid = parse_tl_path(tl_part)
+    tl = list_for(user, lid) if lid else None
+    if not tl:
+        return Response('Not found', 404)
+    try:
+        root = ET.fromstring(request.data or b'<x/>')
+    except ET.ParseError:
+        return Response('Malformed XML', 400)
+    changed = False
+    for el in root.iter():
+        tag = (el.tag.split('}', 1)[1] if '}' in el.tag else el.tag).lower()
+        if tag == 'displayname' and el.text:
+            tl.name = el.text
+            changed = True
+        elif tag == 'calendar-color' and el.text:
+            tl.color = el.text[:7]
+            changed = True
+    if changed:
+        db.session.commit()
+    multi = ET.Element(_qn('d', 'multistatus'))
+    resp = ET.SubElement(multi, _qn('d', 'response'))
+    ET.SubElement(resp, _qn('d', 'href')).text = href_list(user.username, tl.id)
+    ps = ET.SubElement(resp, _qn('d', 'propstat'))
+    ET.SubElement(ps, _qn('d', 'status')).text = 'HTTP/1.1 200 OK'
+    return _xml_response(multi)
+
+
+def tl_mkcol(username, tl_part):
+    """Erstelle eine neue TaskList per MKCOL/MKCALENDAR. Der Pfadteil
+    `tl-N` ist bei MKCOL aber unbekannt - DAVx5 schickt einen frei
+    gewaehlten Namen wie `mein-task-uuid`. Daher: wir akzeptieren jeden
+    Pfadteil und legen eine TaskList an."""
+    user: User = request.dav_user
+    if username != user.username:
+        return Response('', 403)
+    name = 'Neue Aufgabenliste'
+    try:
+        body = request.get_data()
+        if body:
+            root = ET.fromstring(body)
+            for el in root.iter():
+                tag = (el.tag.split('}', 1)[1] if '}' in el.tag else el.tag).lower()
+                if tag == 'displayname' and el.text:
+                    name = el.text
+    except ET.ParseError:
+        pass
+    tl = TaskList(owner_id=user.id, name=name)
+    db.session.add(tl)
+    db.session.commit()
+    notify_tasklist_change(user.id, tl.id, 'created')
+    return Response('', 201, {'Location': href_list(user.username, tl.id)})

backend/app/models/__init__.py

@@ -2,16 +2,19 @@ from app.models.user import User
 from app.models.file import File, FilePermission, ShareLink
 from app.models.calendar import Calendar, CalendarEvent, CalendarShare
 from app.models.contact import AddressBook, Contact, AddressBookShare
+from app.models.task import TaskList, Task, TaskListShare
 from app.models.email_account import EmailAccount
 from app.models.password_vault import PasswordFolder, PasswordEntry, PasswordShare
 from app.models.settings import AppSettings
 from app.models.backup_target import BackupTarget
+from app.models.file_lock import FileLock
 
 __all__ = [
     'User',
     'File', 'FilePermission', 'ShareLink',
     'Calendar', 'CalendarEvent', 'CalendarShare',
     'AddressBook', 'Contact', 'AddressBookShare',
+    'TaskList', 'Task', 'TaskListShare',
     'EmailAccount',
     'PasswordFolder', 'PasswordEntry', 'PasswordShare',
     'AppSettings',

backend/app/models/calendar.py

@@ -12,6 +12,7 @@ class Calendar(db.Model):
     color = db.Column(db.String(7), default='#3788d8')
     description = db.Column(db.Text, nullable=True)
     ical_token = db.Column(db.String(64), unique=True, nullable=True, index=True)
+    ical_password_hash = db.Column(db.String(255), nullable=True)
     created_at = db.Column(db.DateTime, default=lambda: datetime.now(timezone.utc))
     updated_at = db.Column(db.DateTime, default=lambda: datetime.now(timezone.utc),
                            onupdate=lambda: datetime.now(timezone.utc))
@@ -20,6 +21,7 @@ class Calendar(db.Model):
                              cascade='all, delete-orphan')
     shares = db.relationship('CalendarShare', backref='calendar', lazy='dynamic',
                              cascade='all, delete-orphan')
+    # Note: `owner` is auto-created as a backref by User.calendars relationship
 
     def to_dict(self):
         return {
@@ -29,6 +31,7 @@ class Calendar(db.Model):
             'color': self.color,
             'description': self.description,
             'ical_token': self.ical_token,
+            'ical_has_password': bool(self.ical_password_hash),
             'created_at': self.created_at.isoformat() if self.created_at else None,
         }
 
@@ -41,10 +44,14 @@ class CalendarEvent(db.Model):
     uid = db.Column(db.String(255), unique=True, nullable=False)
     ical_data = db.Column(db.Text, nullable=False)  # Full VCALENDAR component
     summary = db.Column(db.String(500), nullable=True)
+    description = db.Column(db.Text, nullable=True)
+    location = db.Column(db.String(500), nullable=True)
     dtstart = db.Column(db.DateTime, nullable=True, index=True)
     dtend = db.Column(db.DateTime, nullable=True)
     all_day = db.Column(db.Boolean, default=False)
     recurrence_rule = db.Column(db.Text, nullable=True)
+    exdates = db.Column(db.Text, nullable=True)  # Komma-separiert, ISO-Datum (YYYY-MM-DD)
+    is_private = db.Column(db.Boolean, default=False, nullable=False)
     created_at = db.Column(db.DateTime, default=lambda: datetime.now(timezone.utc))
     updated_at = db.Column(db.DateTime, default=lambda: datetime.now(timezone.utc),
                            onupdate=lambda: datetime.now(timezone.utc))
@@ -55,10 +62,14 @@ class CalendarEvent(db.Model):
             'calendar_id': self.calendar_id,
             'uid': self.uid,
             'summary': self.summary,
+            'description': self.description,
+            'location': self.location,
             'dtstart': self.dtstart.isoformat() if self.dtstart else None,
             'dtend': self.dtend.isoformat() if self.dtend else None,
             'all_day': self.all_day,
             'recurrence_rule': self.recurrence_rule,
+            'exdates': self.exdates.split(',') if self.exdates else [],
+            'is_private': bool(self.is_private),
             'created_at': self.created_at.isoformat() if self.created_at else None,
             'updated_at': self.updated_at.isoformat() if self.updated_at else None,
         }
@@ -71,6 +82,7 @@ class CalendarShare(db.Model):
     calendar_id = db.Column(db.Integer, db.ForeignKey('calendars.id'), nullable=False, index=True)
     shared_with_id = db.Column(db.Integer, db.ForeignKey('users.id'), nullable=False, index=True)
     permission = db.Column(db.String(20), nullable=False, default='read')  # 'read' or 'readwrite'
+    color = db.Column(db.String(7), nullable=True)  # Persoenliche Anzeige-Farbe
 
     shared_with = db.relationship('User', backref='shared_calendars')
 

backend/app/models/contact.py

@@ -10,6 +10,7 @@ class AddressBook(db.Model):
     owner_id = db.Column(db.Integer, db.ForeignKey('users.id'), nullable=False, index=True)
     name = db.Column(db.String(255), nullable=False)
     description = db.Column(db.Text, nullable=True)
+    color = db.Column(db.String(7), default='#3788d8')
     created_at = db.Column(db.DateTime, default=lambda: datetime.now(timezone.utc))
     updated_at = db.Column(db.DateTime, default=lambda: datetime.now(timezone.utc),
                            onupdate=lambda: datetime.now(timezone.utc))
@@ -18,6 +19,7 @@ class AddressBook(db.Model):
                                cascade='all, delete-orphan')
     shares = db.relationship('AddressBookShare', backref='address_book', lazy='dynamic',
                              cascade='all, delete-orphan')
+    # `owner` wird automatisch durch User.address_books backref erzeugt
 
     def to_dict(self):
         return {
@@ -25,6 +27,7 @@ class AddressBook(db.Model):
             'owner_id': self.owner_id,
             'name': self.name,
             'description': self.description,
+            'color': self.color,
             'created_at': self.created_at.isoformat() if self.created_at else None,
         }
 
@@ -36,22 +39,92 @@ class Contact(db.Model):
     address_book_id = db.Column(db.Integer, db.ForeignKey('address_books.id'),
                                 nullable=False, index=True)
     uid = db.Column(db.String(255), unique=True, nullable=False)
-    vcard_data = db.Column(db.Text, nullable=False)  # Full VCARD
+    vcard_data = db.Column(db.Text, nullable=False)
+
+    # Structured name fields
+    prefix = db.Column(db.String(64), nullable=True)
+    first_name = db.Column(db.String(128), nullable=True)
+    middle_name = db.Column(db.String(128), nullable=True)
+    last_name = db.Column(db.String(128), nullable=True, index=True)
+    suffix = db.Column(db.String(64), nullable=True)
     display_name = db.Column(db.String(255), nullable=True, index=True)
+    nickname = db.Column(db.String(128), nullable=True)
+
+    # Organisation
+    organization = db.Column(db.String(255), nullable=True)
+    department = db.Column(db.String(255), nullable=True)
+    job_title = db.Column(db.String(255), nullable=True)
+
+    # Primary fields for quick listing (denormalised)
+    primary_email = db.Column(db.String(255), nullable=True, index=True)
+    primary_phone = db.Column(db.String(50), nullable=True)
+
+    # JSON-encoded multi-valued fields
+    # Each list entry: {"type": "home|work|other|mobile|fax|pager|...", "value": "..."}
+    emails = db.Column(db.Text, nullable=True)
+    phones = db.Column(db.Text, nullable=True)
+    # address: {"type": ..., "street": ..., "po_box": ..., "city": ...,
+    #           "region": ..., "postal_code": ..., "country": ...}
+    addresses = db.Column(db.Text, nullable=True)
+    websites = db.Column(db.Text, nullable=True)
+    impp = db.Column(db.Text, nullable=True)     # {"protocol": "skype", "value": "..."}
+    categories = db.Column(db.Text, nullable=True)  # ["family", "work", ...]
+
+    # Dates
+    birthday = db.Column(db.String(10), nullable=True)    # YYYY-MM-DD
+    anniversary = db.Column(db.String(10), nullable=True)
+
+    # Free text
+    notes = db.Column(db.Text, nullable=True)
+
+    # Photo: data URL (data:image/jpeg;base64,...) oder http(s)://
+    photo = db.Column(db.Text, nullable=True)
+
+    # Legacy column kept for old clients / migrations
     email = db.Column(db.String(255), nullable=True)
     phone = db.Column(db.String(50), nullable=True)
+
     created_at = db.Column(db.DateTime, default=lambda: datetime.now(timezone.utc))
     updated_at = db.Column(db.DateTime, default=lambda: datetime.now(timezone.utc),
                            onupdate=lambda: datetime.now(timezone.utc))
 
     def to_dict(self):
+        import json
+
+        def _loads(s, default):
+            if not s:
+                return default
+            try:
+                return json.loads(s)
+            except (ValueError, TypeError):
+                return default
+
         return {
             'id': self.id,
             'address_book_id': self.address_book_id,
             'uid': self.uid,
+            'prefix': self.prefix,
+            'first_name': self.first_name,
+            'middle_name': self.middle_name,
+            'last_name': self.last_name,
+            'suffix': self.suffix,
             'display_name': self.display_name,
-            'email': self.email,
+            'nickname': self.nickname,
-            'phone': self.phone,
+            'organization': self.organization,
+            'department': self.department,
+            'job_title': self.job_title,
+            'emails': _loads(self.emails, []),
+            'phones': _loads(self.phones, []),
+            'addresses': _loads(self.addresses, []),
+            'websites': _loads(self.websites, []),
+            'impp': _loads(self.impp, []),
+            'categories': _loads(self.categories, []),
+            'birthday': self.birthday,
+            'anniversary': self.anniversary,
+            'notes': self.notes,
+            'photo': self.photo,
+            'primary_email': self.primary_email or self.email,
+            'primary_phone': self.primary_phone or self.phone,
             'created_at': self.created_at.isoformat() if self.created_at else None,
             'updated_at': self.updated_at.isoformat() if self.updated_at else None,
         }
@@ -65,6 +138,7 @@ class AddressBookShare(db.Model):
                                 nullable=False, index=True)
     shared_with_id = db.Column(db.Integer, db.ForeignKey('users.id'), nullable=False, index=True)
     permission = db.Column(db.String(20), nullable=False, default='read')
+    color = db.Column(db.String(7), nullable=True)  # personal display color
 
     shared_with = db.relationship('User', backref='shared_address_books')
 

backend/app/models/file.py

@@ -55,8 +55,11 @@ class FilePermission(db.Model):
     file_id = db.Column(db.Integer, db.ForeignKey('files.id'), nullable=False, index=True)
     user_id = db.Column(db.Integer, db.ForeignKey('users.id'), nullable=False, index=True)
     permission = db.Column(db.String(20), nullable=False)  # 'read', 'write', 'admin'
+    can_reshare = db.Column(db.Boolean, default=False, nullable=False)
+    granted_by = db.Column(db.Integer, db.ForeignKey('users.id'), nullable=True)
 
-    user = db.relationship('User', backref='file_permissions')
+    user = db.relationship('User', foreign_keys=[user_id], backref='file_permissions')
+    grantor = db.relationship('User', foreign_keys=[granted_by])
 
     __table_args__ = (
         db.UniqueConstraint('file_id', 'user_id', name='uq_file_user_permission'),

backend/app/models/file_lock.py

@@ -0,0 +1,59 @@
+from datetime import datetime, timezone, timedelta
+
+from app.extensions import db
+
+# Lock expires after 15 minutes without heartbeat
+# Client sends heartbeat every 10 seconds and refreshes JWT every 10 minutes
+LOCK_TIMEOUT_MINUTES = 15
+
+
+class FileLock(db.Model):
+    __tablename__ = 'file_locks'
+
+    id = db.Column(db.Integer, primary_key=True)
+    file_id = db.Column(db.Integer, db.ForeignKey('files.id'), unique=True, nullable=False, index=True)
+    locked_by = db.Column(db.Integer, db.ForeignKey('users.id'), nullable=False)
+    locked_at = db.Column(db.DateTime, default=lambda: datetime.now(timezone.utc), nullable=False)
+    heartbeat_at = db.Column(db.DateTime, default=lambda: datetime.now(timezone.utc), nullable=False)
+    client_info = db.Column(db.String(255), nullable=True)  # e.g. "Desktop-Client Windows"
+
+    file = db.relationship('File', backref=db.backref('lock', uselist=False))
+    user = db.relationship('User', backref='file_locks')
+
+    def is_expired(self):
+        cutoff = datetime.now(timezone.utc) - timedelta(minutes=LOCK_TIMEOUT_MINUTES)
+        return self.heartbeat_at.replace(tzinfo=timezone.utc) < cutoff
+
+    def to_dict(self):
+        return {
+            'id': self.id,
+            'file_id': self.file_id,
+            'locked_by': self.locked_by,
+            'locked_by_username': self.user.username if self.user else None,
+            'locked_at': self.locked_at.isoformat() if self.locked_at else None,
+            'heartbeat_at': self.heartbeat_at.isoformat() if self.heartbeat_at else None,
+            'client_info': self.client_info,
+            'is_expired': self.is_expired(),
+        }
+
+    @staticmethod
+    def cleanup_expired():
+        """Remove all expired locks."""
+        cutoff = datetime.now(timezone.utc) - timedelta(minutes=LOCK_TIMEOUT_MINUTES)
+        expired = FileLock.query.filter(FileLock.heartbeat_at < cutoff).all()
+        count = len(expired)
+        for lock in expired:
+            db.session.delete(lock)
+        if count:
+            db.session.commit()
+        return count
+
+    @staticmethod
+    def get_lock(file_id):
+        """Get active (non-expired) lock for a file, cleaning up expired ones."""
+        lock = FileLock.query.filter_by(file_id=file_id).first()
+        if lock and lock.is_expired():
+            db.session.delete(lock)
+            db.session.commit()
+            return None
+        return lock

backend/app/models/task.py

@@ -0,0 +1,86 @@
+from datetime import datetime, timezone
+
+from app.extensions import db
+
+
+class TaskList(db.Model):
+    __tablename__ = 'task_lists'
+
+    id = db.Column(db.Integer, primary_key=True)
+    owner_id = db.Column(db.Integer, db.ForeignKey('users.id'), nullable=False, index=True)
+    name = db.Column(db.String(255), nullable=False)
+    color = db.Column(db.String(7), default='#10b981')
+    description = db.Column(db.Text, nullable=True)
+    created_at = db.Column(db.DateTime, default=lambda: datetime.now(timezone.utc))
+    updated_at = db.Column(db.DateTime, default=lambda: datetime.now(timezone.utc),
+                           onupdate=lambda: datetime.now(timezone.utc))
+
+    tasks = db.relationship('Task', backref='task_list', lazy='dynamic',
+                            cascade='all, delete-orphan')
+    shares = db.relationship('TaskListShare', backref='task_list', lazy='dynamic',
+                             cascade='all, delete-orphan')
+
+    def to_dict(self):
+        return {
+            'id': self.id,
+            'owner_id': self.owner_id,
+            'name': self.name,
+            'color': self.color,
+            'description': self.description,
+            'created_at': self.created_at.isoformat() if self.created_at else None,
+        }
+
+
+class Task(db.Model):
+    __tablename__ = 'tasks'
+
+    id = db.Column(db.Integer, primary_key=True)
+    task_list_id = db.Column(db.Integer, db.ForeignKey('task_lists.id'), nullable=False, index=True)
+    uid = db.Column(db.String(255), unique=True, nullable=False)
+    ical_data = db.Column(db.Text, nullable=False, default='')  # Full VTODO block
+    summary = db.Column(db.String(500), nullable=True)
+    description = db.Column(db.Text, nullable=True)
+    status = db.Column(db.String(32), nullable=True)  # NEEDS-ACTION | IN-PROCESS | COMPLETED | CANCELLED
+    priority = db.Column(db.Integer, nullable=True)  # 0 (keine) - 9
+    percent_complete = db.Column(db.Integer, nullable=True)  # 0..100
+    due = db.Column(db.DateTime, nullable=True, index=True)
+    dtstart = db.Column(db.DateTime, nullable=True)
+    completed_at = db.Column(db.DateTime, nullable=True)
+    categories = db.Column(db.Text, nullable=True)  # kommagetrennt
+    created_at = db.Column(db.DateTime, default=lambda: datetime.now(timezone.utc))
+    updated_at = db.Column(db.DateTime, default=lambda: datetime.now(timezone.utc),
+                           onupdate=lambda: datetime.now(timezone.utc))
+
+    def to_dict(self):
+        return {
+            'id': self.id,
+            'task_list_id': self.task_list_id,
+            'uid': self.uid,
+            'summary': self.summary,
+            'description': self.description,
+            'status': self.status or 'NEEDS-ACTION',
+            'priority': self.priority,
+            'percent_complete': self.percent_complete,
+            'due': self.due.isoformat() if self.due else None,
+            'dtstart': self.dtstart.isoformat() if self.dtstart else None,
+            'completed_at': self.completed_at.isoformat() if self.completed_at else None,
+            'categories': self.categories.split(',') if self.categories else [],
+            'created_at': self.created_at.isoformat() if self.created_at else None,
+            'updated_at': self.updated_at.isoformat() if self.updated_at else None,
+        }
+
+
+class TaskListShare(db.Model):
+    __tablename__ = 'task_list_shares'
+
+    id = db.Column(db.Integer, primary_key=True)
+    task_list_id = db.Column(db.Integer, db.ForeignKey('task_lists.id'), nullable=False, index=True)
+    shared_with_id = db.Column(db.Integer, db.ForeignKey('users.id'), nullable=False, index=True)
+    permission = db.Column(db.String(20), nullable=False, default='read')
+    color = db.Column(db.String(7), nullable=True)
+
+    shared_with = db.relationship('User', backref='shared_task_lists')
+
+    __table_args__ = (
+        db.UniqueConstraint('task_list_id', 'shared_with_id', name='uq_task_list_share'),
+    )

backend/app/models/user.py

@@ -9,6 +9,8 @@ class User(db.Model):
     id = db.Column(db.Integer, primary_key=True)
     username = db.Column(db.String(80), unique=True, nullable=False, index=True)
     email = db.Column(db.String(255), unique=True, nullable=True)
+    first_name = db.Column(db.String(100), nullable=True)
+    last_name = db.Column(db.String(100), nullable=True)
     password_hash = db.Column(db.String(255), nullable=False)
     role = db.Column(db.String(20), default='user', nullable=False)  # 'admin' or 'user'
     master_key_salt = db.Column(db.LargeBinary, nullable=True)  # For password manager
@@ -23,6 +25,7 @@ class User(db.Model):
                             foreign_keys='File.owner_id')
     calendars = db.relationship('Calendar', backref='owner', lazy='dynamic')
     address_books = db.relationship('AddressBook', backref='owner', lazy='dynamic')
+    task_lists = db.relationship('TaskList', backref='owner', lazy='dynamic')
     email_accounts = db.relationship('EmailAccount', backref='user', lazy='dynamic',
                                      order_by='EmailAccount.sort_order')
     password_folders = db.relationship('PasswordFolder', backref='owner', lazy='dynamic')
@@ -33,10 +36,25 @@ class User(db.Model):
     def check_password(self, password):
         return bcrypt.check_password_hash(self.password_hash, password)
 
+    @property
+    def full_name(self) -> str:
+        """Vor- + Nachname zusammengesetzt, sonst Leerstring."""
+        parts = [self.first_name or '', self.last_name or '']
+        return ' '.join(p.strip() for p in parts if p and p.strip())
+
+    @property
+    def display_name(self) -> str:
+        """Voller Name falls vorhanden, sonst Username."""
+        return self.full_name or self.username
+
     def to_dict(self, include_email=False):
         data = {
             'id': self.id,
             'username': self.username,
+            'first_name': self.first_name or '',
+            'last_name': self.last_name or '',
+            'full_name': self.full_name,
+            'display_name': self.display_name,
             'role': self.role,
             'is_active': self.is_active,
             'storage_quota_mb': self.storage_quota_mb,

backend/app/services/events.py

@@ -0,0 +1,104 @@
+"""In-memory event broadcaster for SSE clients.
+
+Each logged-in user can have multiple connected clients (desktop, web,
+mobile). Every client gets its own queue. Mutating file operations push
+an event into the queues of every affected user.
+"""
+from __future__ import annotations
+
+import json
+import queue
+import threading
+import time
+from typing import Iterable
+
+
+class EventBroadcaster:
+    def __init__(self) -> None:
+        self._lock = threading.Lock()
+        # user_id -> list[queue.Queue]
+        self._subs: dict[int, list[queue.Queue]] = {}
+
+    def subscribe(self, user_id: int) -> queue.Queue:
+        q: queue.Queue = queue.Queue(maxsize=256)
+        with self._lock:
+            self._subs.setdefault(user_id, []).append(q)
+        return q
+
+    def unsubscribe(self, user_id: int, q: queue.Queue) -> None:
+        with self._lock:
+            lst = self._subs.get(user_id)
+            if not lst:
+                return
+            try:
+                lst.remove(q)
+            except ValueError:
+                pass
+            if not lst:
+                self._subs.pop(user_id, None)
+
+    def publish(self, user_ids: Iterable[int], event: dict) -> None:
+        payload = dict(event)
+        payload.setdefault('ts', time.time())
+        with self._lock:
+            for uid in set(user_ids):
+                for q in self._subs.get(uid, []):
+                    try:
+                        q.put_nowait(payload)
+                    except queue.Full:
+                        pass  # slow client - drop event
+
+    def stream(self, user_id: int):
+        """Generator yielding SSE-formatted strings for one client."""
+        q = self.subscribe(user_id)
+        try:
+            # Initial hello so the client knows it's connected
+            yield f"event: hello\ndata: {json.dumps({'user_id': user_id})}\n\n"
+            while True:
+                try:
+                    event = q.get(timeout=20.0)
+                except queue.Empty:
+                    # Heartbeat / keepalive comment - also keeps proxies happy
+                    yield ": keepalive\n\n"
+                    continue
+                kind = event.get('type', 'change')
+                yield f"event: {kind}\ndata: {json.dumps(event)}\n\n"
+        finally:
+            self.unsubscribe(user_id, q)
+
+
+broadcaster = EventBroadcaster()
+
+
+def notify_file_change(owner_id: int, file_id: int | None, change: str,
+                       shared_with: Iterable[int] = ()) -> None:
+    """Emit a file change event to the owner plus any users with share access."""
+    recipients = [owner_id, *shared_with]
+    broadcaster.publish(recipients, {
+        'type': 'file',
+        'change': change,  # 'created' | 'updated' | 'deleted' | 'locked' | 'unlocked'
+        'file_id': file_id,
+    })
+
+
+def notify_calendar_change(owner_id: int, calendar_id: int, change: str,
+                           shared_with: Iterable[int] = ()) -> None:
+    """Emit a calendar-level change event (event added/changed/deleted or
+    share membership changed). Sent to owner + all users the calendar is
+    shared with."""
+    recipients = [owner_id, *shared_with]
+    broadcaster.publish(recipients, {
+        'type': 'calendar',
+        'change': change,  # 'event'|'share'|'deleted'
+        'calendar_id': calendar_id,
+    })
+
+
+def notify_tasklist_change(owner_id: int, list_id: int, change: str,
+                           shared_with: Iterable[int] = ()) -> None:
+    recipients = [owner_id, *shared_with]
+    broadcaster.publish(recipients, {
+        'type': 'tasklist',
+        'change': change,  # 'task'|'share'|'deleted'|'created'
+        'task_list_id': list_id,
+    })

backend/app/services/ntp_check.py

@@ -0,0 +1,56 @@
+"""Leichtgewichtiger SNTP-Client zum Pruefen des Zeit-Offsets.
+
+Im Container koennen wir die Systemzeit nicht wirklich setzen (braucht
+CAP_SYS_TIME). Aber wir koennen den Offset ermitteln und loggen, damit
+der Admin weiss, ob der Host driftet. Fuer einen harten Sync muss auf
+dem Host selbst ein NTP-Daemon laufen.
+"""
+from __future__ import annotations
+
+import socket
+import struct
+import time
+
+_NTP_EPOCH_OFFSET = 2208988800  # Sekunden zwischen 1900 und 1970
+
+
+def query_ntp(server: str, timeout: float = 3.0, port: int = 123) -> float | None:
+    """Fragt einen NTP-Server und gibt das Offset (Server - Local) in
+    Sekunden zurueck, oder None bei Fehler."""
+    packet = b'\x1b' + 47 * b'\0'  # LI=0, VN=3, Mode=3 (client)
+    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+    sock.settimeout(timeout)
+    try:
+        t0 = time.time()
+        sock.sendto(packet, (server, port))
+        data, _ = sock.recvfrom(1024)
+        t3 = time.time()
+    except (socket.gaierror, socket.timeout, OSError):
+        return None
+    finally:
+        sock.close()
+
+    if len(data) < 48:
+        return None
+    # Transmit timestamp: Offset 40, 8 bytes, fixed point 32.32
+    secs, frac = struct.unpack('!II', data[40:48])
+    if secs == 0:
+        return None
+    t2 = secs - _NTP_EPOCH_OFFSET + frac / 2**32
+    # Einfacher Offset (sans roundtrip): (t2 - ((t0 + t3) / 2))
+    return t2 - (t0 + t3) / 2
+
+
+def check_and_log(server: str, logger=None) -> float | None:
+    import logging
+    log = logger or logging.getLogger('ntp')
+    offset = query_ntp(server)
+    if offset is None:
+        log.warning('NTP-Check: Server %s nicht erreichbar', server)
+        return None
+    if abs(offset) > 5.0:
+        log.warning('NTP-Check: Systemzeit weicht um %.2fs von %s ab -> Host-Uhr synchronisieren!',
+                    offset, server)
+    else:
+        log.info('NTP-Check: Offset %.3fs gegen %s (ok)', offset, server)
+    return offset

backend/app/services/system_mail.py

@@ -179,3 +179,32 @@ def notify_user_created(user, created_by_username):
         f'Deine Mini-Cloud'
     )
     send_system_email(user.email, subject, body)
+
+
+def notify_conflict_to_admin(conflict_user, conflict_file_name, conflict_copy_name,
+                             folder_path, lock_user_name, lock_user_email, locked_since):
+    """Notify admin about a sync conflict (user edited a locked file)."""
+    from app.models.settings import AppSettings
+
+    admin_email = AppSettings.get('system_email_from', '')
+    if not admin_email:
+        return
+
+    subject = f'Mini-Cloud: Datei-Konflikt - {conflict_file_name}'
+    body = (
+        f'Datei-Konflikt in der Mini-Cloud!\n\n'
+        f'Benutzer:         {conflict_user.username}'
+        f'{" (" + conflict_user.email + ")" if conflict_user.email else ""}\n'
+        f'Hat bearbeitet:   {conflict_file_name}\n'
+        f'Ordner:           {folder_path}\n'
+        f'Konflikt-Kopie:   {conflict_copy_name}\n\n'
+        f'Gesperrt von:     {lock_user_name}'
+        f'{" (" + lock_user_email + ")" if lock_user_email else ""}\n'
+        f'Gesperrt seit:    {locked_since}\n\n'
+        f'Ursache: {conflict_user.username} hat die Datei lokal bearbeitet '
+        f'waehrend {lock_user_name} sie ausgecheckt hatte.\n\n'
+        f'Die Aenderungen von {conflict_user.username} wurden als '
+        f'Konflikt-Kopie gespeichert und muessen manuell zusammengefuehrt werden.\n\n'
+        f'Deine Mini-Cloud'
+    )
+    send_system_email(admin_email, subject, body)

build.sh

@@ -0,0 +1,255 @@
+#!/bin/bash
+#
+# Mini-Cloud Client Build Script
+# Baut Desktop- und Mobile-Clients via Docker (kein lokales Setup noetig)
+#
+# Verwendung:
+#   ./build.sh linux        # Linux Desktop (.deb + .AppImage)
+#   ./build.sh windows      # Windows Desktop (.msi + .exe)
+#   ./build.sh mac          # macOS Desktop (.dmg) - nur auf macOS moeglich
+#   ./build.sh android      # Android App (.apk)
+#   ./build.sh ios          # iOS App (.ipa) - nur auf macOS moeglich
+#   ./build.sh all-desktop  # Linux + Windows
+#   ./build.sh clean        # Build-Cache loeschen
+#
+# Nach dem Build wird der Client automatisch auf den Server hochgeladen
+# wenn CLOUD_URL und BUILD_UPLOAD_TOKEN in .env gesetzt sind.
+#
+
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+DESKTOP_DIR="$SCRIPT_DIR/clients/desktop"
+MOBILE_DIR="$SCRIPT_DIR/clients/mobile"
+OUTPUT_DIR="$SCRIPT_DIR/build-output"
+
+RED='\033[0;31m'
+GREEN='\033[0;32m'
+YELLOW='\033[1;33m'
+NC='\033[0m'
+
+info()  { echo -e "${GREEN}[BUILD]${NC} $1"; }
+warn()  { echo -e "${YELLOW}[WARN]${NC} $1"; }
+error() { echo -e "${RED}[ERROR]${NC} $1"; exit 1; }
+
+# Load .env if exists
+if [ -f "$SCRIPT_DIR/.env" ]; then
+    export $(grep -v '^#' "$SCRIPT_DIR/.env" | grep -E '^(CLOUD_URL|BUILD_UPLOAD_TOKEN)=' | xargs)
+fi
+
+mkdir -p "$OUTPUT_DIR"
+
+upload_to_server() {
+    local platform="$1"
+    local filepath="$2"
+
+    if [ -z "$CLOUD_URL" ] || [ -z "$BUILD_UPLOAD_TOKEN" ]; then
+        warn "CLOUD_URL oder BUILD_UPLOAD_TOKEN nicht gesetzt - Upload uebersprungen"
+        warn "Setze beide in .env fuer automatischen Upload"
+        return
+    fi
+
+    local filename=$(basename "$filepath")
+    info "Lade $filename auf $CLOUD_URL hoch..."
+
+    local http_code
+    http_code=$(curl -s -o /tmp/upload_response.txt -w "%{http_code}" \
+        -X POST "$CLOUD_URL/api/clients/$platform/upload" \
+        -H "X-Build-Token: $BUILD_UPLOAD_TOKEN" \
+        -F "file=@$filepath")
+
+    if [ "$http_code" = "200" ]; then
+        info "Upload erfolgreich: $filename -> $CLOUD_URL"
+        cat /tmp/upload_response.txt | python3 -m json.tool 2>/dev/null || cat /tmp/upload_response.txt
+    elif [ "$http_code" = "403" ]; then
+        error "Upload fehlgeschlagen: BUILD_UPLOAD_TOKEN ist falsch!"
+        echo ""
+        echo "  Der BUILD_UPLOAD_TOKEN in deiner .env muss der SECRET_KEY"
+        echo "  oder JWT_SECRET_KEY vom Zielserver sein."
+        echo ""
+        echo "  Pruefe auf dem Server: grep SECRET_KEY /pfad/zur/.env"
+        echo "  Dann den Wert in die lokale .env als BUILD_UPLOAD_TOKEN kopieren."
+        echo ""
+    elif [ "$http_code" = "000" ]; then
+        error "Upload fehlgeschlagen: Server nicht erreichbar ($CLOUD_URL)"
+    else
+        warn "Upload fehlgeschlagen (HTTP $http_code)"
+        cat /tmp/upload_response.txt 2>/dev/null
+    fi
+    rm -f /tmp/upload_response.txt
+}
+
+build_linux() {
+    info "Baue Linux Desktop Client..."
+    cd "$DESKTOP_DIR"
+
+    sudo docker build -f Dockerfile.build -t minicloud-desktop-builder .
+
+    sudo docker run --rm \
+        -v "$OUTPUT_DIR:/output" \
+        minicloud-desktop-builder \
+        bash -c "npm run tauri build && cp -r src-tauri/target/release/bundle/* /output/ 2>/dev/null; \
+                 cp src-tauri/target/release/minicloud-sync /output/ 2>/dev/null; \
+                 echo 'Linux Build fertig!'"
+
+    info "Linux Build fertig! Dateien in: $OUTPUT_DIR/"
+
+    # Upload best file (AppImage > deb > binary)
+    local upload_file=""
+    for f in "$OUTPUT_DIR"/*.AppImage "$OUTPUT_DIR"/*.deb "$OUTPUT_DIR"/minicloud-sync; do
+        if [ -f "$f" ]; then upload_file="$f"; break; fi
+    done
+    [ -n "$upload_file" ] && upload_to_server "linux" "$upload_file"
+}
+
+build_windows() {
+    info "Baue Windows Desktop Client (Cross-Compile)..."
+    cd "$DESKTOP_DIR"
+
+    sudo docker build -f Dockerfile.build -t minicloud-desktop-builder .
+
+    sudo docker run --rm \
+        -v "$OUTPUT_DIR:/output" \
+        -e CARGO_TARGET_X86_64_PC_WINDOWS_GNU_LINKER=x86_64-w64-mingw32-gcc \
+        minicloud-desktop-builder \
+        bash -c "npm run tauri build -- --target x86_64-pc-windows-gnu 2>&1 || true; \
+                 find src-tauri/target -name '*.exe' -o -name '*.msi' | head -5; \
+                 cp src-tauri/target/x86_64-pc-windows-gnu/release/*.exe /output/ 2>/dev/null; \
+                 cp -r src-tauri/target/x86_64-pc-windows-gnu/release/bundle/* /output/ 2>/dev/null; \
+                 echo 'Windows Build fertig!'"
+
+    info "Windows Build fertig! Dateien in: $OUTPUT_DIR/"
+
+    # Upload setup installer (NSIS with WebView2 bundled), not the naked .exe
+    local upload_file=""
+    for f in "$OUTPUT_DIR"/nsis/*setup*.exe "$OUTPUT_DIR"/*.msi "$OUTPUT_DIR"/nsis/*.exe; do
+        if [ -f "$f" ]; then upload_file="$f"; break; fi
+    done
+    [ -n "$upload_file" ] && upload_to_server "windows" "$upload_file"
+}
+
+build_mac() {
+    # macOS kann nicht cross-compiled werden, muss auf macOS laufen
+    if [[ "$(uname)" != "Darwin" ]]; then
+        error "macOS Build ist nur auf macOS moeglich!"
+    fi
+
+    info "Baue macOS Desktop Client..."
+    cd "$DESKTOP_DIR"
+    npm install
+    npm run tauri build
+
+    cp -r src-tauri/target/release/bundle/* "$OUTPUT_DIR/" 2>/dev/null
+    info "macOS Build fertig! Dateien in: $OUTPUT_DIR/"
+
+    local upload_file=""
+    for f in "$OUTPUT_DIR"/*.dmg; do
+        if [ -f "$f" ]; then upload_file="$f"; break; fi
+    done
+    [ -n "$upload_file" ] && upload_to_server "mac" "$upload_file"
+}
+
+build_android() {
+    if [ ! -d "$MOBILE_DIR" ]; then
+        error "Mobile Client noch nicht erstellt (clients/mobile/)"
+    fi
+
+    info "Baue Android App..."
+    cd "$MOBILE_DIR"
+
+    sudo docker run --rm \
+        -v "$MOBILE_DIR:/app" \
+        -v "$OUTPUT_DIR:/output" \
+        ghcr.io/nickvdyck/flutter-android:latest \
+        bash -c "cd /app && flutter pub get && flutter build apk --release && \
+                 cp build/app/outputs/flutter-apk/app-release.apk /output/minicloud.apk && \
+                 echo 'Android Build fertig!'"
+
+    info "Android APK: $OUTPUT_DIR/minicloud.apk"
+    [ -f "$OUTPUT_DIR/minicloud.apk" ] && upload_to_server "android" "$OUTPUT_DIR/minicloud.apk"
+}
+
+build_ios() {
+    if [[ "$(uname)" != "Darwin" ]]; then
+        error "iOS Build ist nur auf macOS moeglich!"
+    fi
+
+    if [ ! -d "$MOBILE_DIR" ]; then
+        error "Mobile Client noch nicht erstellt (clients/mobile/)"
+    fi
+
+    info "Baue iOS App..."
+    cd "$MOBILE_DIR"
+    flutter pub get
+    flutter build ios --release
+
+    info "iOS Build fertig! Oeffne Xcode fuer Signierung + Archive."
+
+    local upload_file=""
+    for f in "$MOBILE_DIR"/build/ios/ipa/*.ipa; do
+        if [ -f "$f" ]; then upload_file="$f"; break; fi
+    done
+    [ -n "$upload_file" ] && upload_to_server "ios" "$upload_file"
+}
+
+do_clean() {
+    info "Loesche Build-Cache..."
+    rm -rf "$OUTPUT_DIR"/*
+    rm -rf "$DESKTOP_DIR/src-tauri/target"
+    rm -rf "$MOBILE_DIR/build" 2>/dev/null
+    sudo docker rmi minicloud-desktop-builder 2>/dev/null || true
+    info "Build-Cache geloescht."
+}
+
+# Main
+case "${1:-help}" in
+    linux)
+        build_linux
+        ;;
+    windows)
+        build_windows
+        ;;
+    mac|macos)
+        build_mac
+        ;;
+    android)
+        build_android
+        ;;
+    ios)
+        build_ios
+        ;;
+    all-desktop)
+        build_linux
+        build_windows
+        ;;
+    clean)
+        do_clean
+        ;;
+    *)
+        echo ""
+        echo "Mini-Cloud Client Build Script"
+        echo ""
+        echo "Verwendung: $0 <ziel>"
+        echo ""
+        echo "Desktop:"
+        echo "  linux        Linux (.deb + .AppImage + Binary)"
+        echo "  windows      Windows (.msi + .exe) - Cross-Compile via Docker"
+        echo "  mac          macOS (.dmg) - nur auf macOS"
+        echo "  all-desktop  Linux + Windows"
+        echo ""
+        echo "Mobile:"
+        echo "  android      Android (.apk) - via Docker"
+        echo "  ios          iOS (.ipa) - nur auf macOS"
+        echo ""
+        echo "Sonstiges:"
+        echo "  clean        Build-Cache loeschen"
+        echo ""
+        echo "Alle Builds (ausser mac/ios) laufen in Docker - kein lokales"
+        echo "Setup noetig. Output landet in: build-output/"
+        echo ""
+        echo "Auto-Upload: Wenn CLOUD_URL und BUILD_UPLOAD_TOKEN in .env"
+        echo "gesetzt sind, wird der Client nach dem Build automatisch auf"
+        echo "den Server hochgeladen und steht zum Download bereit."
+        echo ""
+        ;;
+esac

clients/desktop/.gitignore

@@ -0,0 +1,24 @@
+# Logs
+logs
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+pnpm-debug.log*
+lerna-debug.log*
+
+node_modules
+dist
+dist-ssr
+*.local
+
+# Editor directories and files
+.vscode/*
+!.vscode/extensions.json
+.idea
+.DS_Store
+*.suo
+*.ntvs*
+*.njsproj
+*.sln
+*.sw?

clients/desktop/CLOUD_FILES.md

@@ -0,0 +1,70 @@
+# Native File-Provider-Integration (Platzhalter-Modus)
+
+Zusaetzlich zum klassischen "alles-kopieren"-Sync bietet der Desktop-Client
+einen **OneDrive-aehnlichen Platzhalter-Modus**: Dateien erscheinen im
+Dateimanager als kleine Metadata-Dateien (Platzhalter) und werden erst
+bei Doppelklick vom Server geladen.
+
+## Status
+
+| Plattform | Status    | Technologie                          |
+| --------- | --------- | ------------------------------------ |
+| Windows   | **MVP**   | Cloud Files API (`cfapi.dll`)        |
+| Linux     | Skelett   | FUSE (libfuse3) - feature `linux_fuse` |
+| macOS     | Geplant   | `NSFileProviderExtension` + Signatur |
+
+## Windows
+
+### Voraussetzungen
+
+- Windows 10 1709 (Build 16299) oder neuer
+- Der Client laeuft als regulaerer Benutzerprozess (keine Admin-Rechte noetig)
+
+### Was funktioniert
+
+- `CfRegisterSyncRoot` registriert einen Ordner als Sync-Root, der Explorer
+  zeigt Wolken-Overlay-Icons an.
+- `CfCreatePlaceholders` legt fuer jede Mini-Cloud-Datei einen Platzhalter
+  mit korrekter Groesse und Aenderungszeit an.
+- `FETCH_DATA`-Callback laedt per Range-Request vom Server, sobald der
+  Explorer Dateidaten anfordert (z.B. beim Oeffnen).
+- `CfSetPinState` erlaubt manuelles "Immer offline halten" / "Nur in Cloud".
+
+### Was noch fehlt
+
+- Upload-Callback (`NOTIFY_FILE_CLOSE_COMPLETION`) fuer lokal geaenderte Dateien
+- Context-Menue "Ein-/Auschecken" via Shell-Extension
+- Delta-Updates (neue/geloeschte Dateien auf dem Server -> lokale Placeholder)
+- Konflikt-Aufloesung
+
+### Einschalten
+
+Im Client-UI den Schalter **"Cloud-Files-Modus"** aktivieren (ruft intern
+`cloud_files_enable`-Command auf). Alternativ per Kommandozeile beim Build:
+
+```powershell
+# Aus clients/desktop/src-tauri:
+cargo build --release
+```
+
+Windows-Targets brauchen das Windows-SDK (uebersetzt aber sauber mit
+cross-compile via `cargo xwin` aus Linux, wenn `build.sh windows` laeuft).
+
+## Linux
+
+FUSE-Provider ist optional und mit einem Feature-Flag versehen, damit
+normale Linux-Builds nicht `libfuse3-dev` voraussetzen:
+
+```bash
+cargo build --features linux_fuse
+```
+
+Overlay-Icons im Dateimanager (Nautilus / Dolphin / Caja) brauchen
+zusaetzlich eine native Extension pro DE - folgt in einem spaeteren
+Commit.
+
+## macOS
+
+Braucht eine Apple Developer ID + Notarization, da `NSFileProviderExtension`
+sonst vom Finder nicht geladen wird. Wird angegangen, sobald ein
+Apple-Dev-Zugang verfuegbar ist.

clients/desktop/Dockerfile.build

@@ -0,0 +1,50 @@
+# Multi-stage build container for Tauri Desktop Client
+# Supports: linux, windows (cross-compile)
+
+FROM rust:1.94-bookworm AS builder
+
+# Install system dependencies for Tauri
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    libwebkit2gtk-4.1-dev \
+    libgtk-3-dev \
+    libayatana-appindicator3-dev \
+    librsvg2-dev \
+    libcairo2-dev \
+    libgdk-pixbuf-2.0-dev \
+    libsoup-3.0-dev \
+    libjavascriptcoregtk-4.1-dev \
+    pkg-config \
+    curl \
+    wget \
+    file \
+    && rm -rf /var/lib/apt/lists/*
+
+# Install Node.js
+RUN curl -fsSL https://deb.nodesource.com/setup_22.x | bash - \
+    && apt-get install -y nodejs \
+    && rm -rf /var/lib/apt/lists/*
+
+# Windows cross-compile tools
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    gcc-mingw-w64-x86-64 \
+    nsis \
+    && rm -rf /var/lib/apt/lists/* \
+    && rustup target add x86_64-pc-windows-gnu || true
+
+WORKDIR /build
+
+# Cache Rust dependencies
+COPY src-tauri/Cargo.toml src-tauri/Cargo.lock* ./src-tauri/
+COPY src-tauri/build.rs ./src-tauri/
+RUN mkdir -p src-tauri/src && echo "pub fn run() {}" > src-tauri/src/lib.rs \
+    && echo "fn main() { minicloud_sync_lib::run() }" > src-tauri/src/main.rs \
+    && cd src-tauri && cargo fetch 2>/dev/null || true
+
+# Copy full source
+COPY . .
+
+# Install npm dependencies
+RUN npm ci
+
+# Default: build for linux
+CMD ["npm", "run", "tauri", "build"]

clients/desktop/README.md

@@ -0,0 +1,7 @@
+# Tauri + Vue 3
+
+This template should help get you started developing with Tauri + Vue 3 in Vite. The template uses Vue 3 `<script setup>` SFCs, check out the [script setup docs](https://v3.vuejs.org/api/sfc-script-setup.html#sfc-script-setup) to learn more.
+
+## Recommended IDE Setup
+
+- [VS Code](https://code.visualstudio.com/) + [Vue - Official](https://marketplace.visualstudio.com/items?itemName=Vue.volar) + [Tauri](https://marketplace.visualstudio.com/items?itemName=tauri-apps.tauri-vscode) + [rust-analyzer](https://marketplace.visualstudio.com/items?itemName=rust-lang.rust-analyzer)

clients/desktop/index.html

@@ -0,0 +1,14 @@
+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <link rel="icon" type="image/svg+xml" href="/vite.svg" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>Tauri + Vue 3 App</title>
+  </head>
+
+  <body>
+    <div id="app"></div>
+    <script type="module" src="/src/main.js"></script>
+  </body>
+</html>

clients/desktop/package.json

@@ -0,0 +1,24 @@
+{
+  "name": "tauri-app",
+  "private": true,
+  "version": "0.1.0",
+  "type": "module",
+  "scripts": {
+    "dev": "vite",
+    "build": "vite build",
+    "preview": "vite preview",
+    "tauri": "tauri"
+  },
+  "dependencies": {
+    "vue": "^3.5.13",
+    "@tauri-apps/api": "^2",
+    "@tauri-apps/plugin-opener": "^2",
+    "@tauri-apps/plugin-dialog": "^2",
+    "@tauri-apps/plugin-notification": "^2"
+  },
+  "devDependencies": {
+    "@vitejs/plugin-vue": "^5.2.1",
+    "vite": "^6.0.3",
+    "@tauri-apps/cli": "^2"
+  }
+}

clients/desktop/public/tauri.svg

@@ -0,0 +1,6 @@
+<svg width="206" height="231" viewBox="0 0 206 231" fill="none" xmlns="http://www.w3.org/2000/svg">
+<path d="M143.143 84C143.143 96.1503 133.293 106 121.143 106C108.992 106 99.1426 96.1503 99.1426 84C99.1426 71.8497 108.992 62 121.143 62C133.293 62 143.143 71.8497 143.143 84Z" fill="#FFC131"/>
+<ellipse cx="84.1426" cy="147" rx="22" ry="22" transform="rotate(180 84.1426 147)" fill="#24C8DB"/>
+<path fill-rule="evenodd" clip-rule="evenodd" d="M166.738 154.548C157.86 160.286 148.023 164.269 137.757 166.341C139.858 160.282 141 153.774 141 147C141 144.543 140.85 142.121 140.558 139.743C144.975 138.204 149.215 136.139 153.183 133.575C162.73 127.404 170.292 118.608 174.961 108.244C179.63 97.8797 181.207 86.3876 179.502 75.1487C177.798 63.9098 172.884 53.4021 165.352 44.8883C157.82 36.3744 147.99 30.2165 137.042 27.1546C126.095 24.0926 114.496 24.2568 103.64 27.6274C92.7839 30.998 83.1319 37.4317 75.8437 46.1553C74.9102 47.2727 74.0206 48.4216 73.176 49.5993C61.9292 50.8488 51.0363 54.0318 40.9629 58.9556C44.2417 48.4586 49.5653 38.6591 56.679 30.1442C67.0505 17.7298 80.7861 8.57426 96.2354 3.77762C111.685 -1.01901 128.19 -1.25267 143.769 3.10474C159.348 7.46215 173.337 16.2252 184.056 28.3411C194.775 40.457 201.767 55.4101 204.193 71.404C206.619 87.3978 204.374 103.752 197.73 118.501C191.086 133.25 180.324 145.767 166.738 154.548ZM41.9631 74.275L62.5557 76.8042C63.0459 72.813 63.9401 68.9018 65.2138 65.1274C57.0465 67.0016 49.2088 70.087 41.9631 74.275Z" fill="#FFC131"/>
+<path fill-rule="evenodd" clip-rule="evenodd" d="M38.4045 76.4519C47.3493 70.6709 57.2677 66.6712 67.6171 64.6132C65.2774 70.9669 64 77.8343 64 85.0001C64 87.1434 64.1143 89.26 64.3371 91.3442C60.0093 92.8732 55.8533 94.9092 51.9599 97.4256C42.4128 103.596 34.8505 112.392 30.1816 122.756C25.5126 133.12 23.9357 144.612 25.6403 155.851C27.3449 167.09 32.2584 177.598 39.7906 186.112C47.3227 194.626 57.153 200.784 68.1003 203.846C79.0476 206.907 90.6462 206.743 101.502 203.373C112.359 200.002 122.011 193.568 129.299 184.845C130.237 183.722 131.131 182.567 131.979 181.383C143.235 180.114 154.132 176.91 164.205 171.962C160.929 182.49 155.596 192.319 148.464 200.856C138.092 213.27 124.357 222.426 108.907 227.222C93.458 232.019 76.9524 232.253 61.3736 227.895C45.7948 223.538 31.8055 214.775 21.0867 202.659C10.3679 190.543 3.37557 175.59 0.949823 159.596C-1.47592 143.602 0.768139 127.248 7.41237 112.499C14.0566 97.7497 24.8183 85.2327 38.4045 76.4519ZM163.062 156.711L163.062 156.711C162.954 156.773 162.846 156.835 162.738 156.897C162.846 156.835 162.954 156.773 163.062 156.711Z" fill="#24C8DB"/>
+</svg>

clients/desktop/public/vite.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" aria-hidden="true" role="img" class="iconify iconify--logos" width="31.88" height="32" preserveAspectRatio="xMidYMid meet" viewBox="0 0 256 257"><defs><linearGradient id="IconifyId1813088fe1fbc01fb466" x1="-.828%" x2="57.636%" y1="7.652%" y2="78.411%"><stop offset="0%" stop-color="#41D1FF"></stop><stop offset="100%" stop-color="#BD34FE"></stop></linearGradient><linearGradient id="IconifyId1813088fe1fbc01fb467" x1="43.376%" x2="50.316%" y1="2.242%" y2="89.03%"><stop offset="0%" stop-color="#FFEA83"></stop><stop offset="8.333%" stop-color="#FFDD35"></stop><stop offset="100%" stop-color="#FFA800"></stop></linearGradient></defs><path fill="url(#IconifyId1813088fe1fbc01fb466)" d="M255.153 37.938L134.897 252.976c-2.483 4.44-8.862 4.466-11.382.048L.875 37.958c-2.746-4.814 1.371-10.646 6.827-9.67l120.385 21.517a6.537 6.537 0 0 0 2.322-.004l117.867-21.483c5.438-.991 9.574 4.796 6.877 9.62Z"></path><path fill="url(#IconifyId1813088fe1fbc01fb467)" d="M185.432.063L96.44 17.501a3.268 3.268 0 0 0-2.634 3.014l-5.474 92.456a3.268 3.268 0 0 0 3.997 3.378l24.777-5.718c2.318-.535 4.413 1.507 3.936 3.838l-7.361 36.047c-.495 2.426 1.782 4.5 4.151 3.78l15.304-4.649c2.372-.72 4.652 1.36 4.15 3.788l-11.698 56.621c-.732 3.542 3.979 5.473 5.943 2.437l1.313-2.028l72.516-144.72c1.215-2.423-.88-5.186-3.54-4.672l-25.505 4.922c-2.396.462-4.435-1.77-3.759-4.114l16.646-57.705c.677-2.35-1.37-4.583-3.769-4.113Z"></path></svg>

clients/desktop/src-tauri/.gitignore

@@ -0,0 +1,7 @@
+# Generated by Cargo
+# will have compiled files and executables
+/target/
+
+# Generated by Tauri
+# will have schema files for capabilities auto-completion
+/gen/schemas

clients/desktop/src-tauri/Cargo.toml

@@ -0,0 +1,57 @@
+[package]
+name = "minicloud-sync"
+version = "0.1.0"
+description = "Mini-Cloud Desktop Sync Client"
+authors = ["Mini-Cloud"]
+edition = "2021"
+
+[lib]
+name = "minicloud_sync_lib"
+crate-type = ["staticlib", "cdylib", "rlib"]
+
+[build-dependencies]
+tauri-build = { version = "2", features = [] }
+
+[dependencies]
+tauri = { version = "2", features = ["tray-icon"] }
+tauri-plugin-opener = "2"
+tauri-plugin-dialog = "2"
+tauri-plugin-notification = "2"
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+reqwest = { version = "0.12", features = ["json", "multipart", "rustls-tls", "blocking"], default-features = false }
+tokio = { version = "1", features = ["full"] }
+notify = "7"
+sha2 = "0.10"
+dirs = "6"
+rusqlite = { version = "0.34", features = ["bundled"] }
+chrono = { version = "0.4", features = ["serde"] }
+base64 = "0.22"
+open = "5"
+once_cell = "1"
+
+# Plattform-spezifische File-Provider-Integration (OneDrive-artig).
+# Nur auf Windows gegen die Cloud Files API (cfapi.dll) linken.
+[target.'cfg(windows)'.dependencies]
+windows = { version = "0.58", features = [
+    "Win32_Foundation",
+    "Win32_Storage_FileSystem",
+    "Win32_Storage_CloudFilters",
+    "Win32_System_IO",
+    "Win32_System_Com",
+    "Win32_System_CorrelationVector",  # gate fuer CF_CALLBACK_INFO / CfExecute / CfConnectSyncRoot
+    "Win32_UI_Shell",
+    "Win32_Security",
+    "Win32_System_Registry",
+] }
+widestring = "1"
+winreg = "0.52"
+
+# Linux: FUSE-basiertes Virtual-Filesystem (optional, cargo build --features linux_fuse)
+[target.'cfg(target_os = "linux")'.dependencies]
+fuser = { version = "0.15", optional = true }
+libc = "0.2"
+
+[features]
+default = []
+linux_fuse = ["fuser"]

clients/desktop/src-tauri/build.rs

@@ -0,0 +1,3 @@
+fn main() {
+    tauri_build::build()
+}

clients/desktop/src-tauri/capabilities/default.json

@@ -0,0 +1,13 @@
+{
+  "$schema": "../gen/schemas/desktop-schema.json",
+  "identifier": "default",
+  "description": "Capability for the main window",
+  "windows": ["main"],
+  "permissions": [
+    "core:default",
+    "opener:default",
+    "dialog:default",
+    "dialog:allow-open",
+    "notification:default"
+  ]
+}

clients/desktop/src-tauri/src/cloud_files/linux.rs

@@ -0,0 +1,25 @@
+//! Linux FUSE-basierte File-Provider-Integration (Platzhalter-Modus).
+//!
+//! Status: Skelett. Funktioniert nur wenn mit `--features linux_fuse`
+//! gebaut wird und `libfuse3-dev` installiert ist. Overlay-Icons im
+//! Dateimanager (Nautilus/Dolphin) werden spaeter als separate Extension
+//! nachgereicht - das FUSE-Filesystem selbst kann die nicht setzen.
+
+#![cfg(all(target_os = "linux", feature = "linux_fuse"))]
+
+use super::RemoteEntry;
+use std::path::PathBuf;
+
+pub fn mount(mount_point: &PathBuf) -> Result<(), String> {
+    std::fs::create_dir_all(mount_point).map_err(|e| e.to_string())?;
+    // TODO: fuser::Filesystem-Impl mit auf-Abruf-Download
+    Err("Linux FUSE-Provider: noch nicht implementiert (MVP folgt)".into())
+}
+
+pub fn unmount(_mount_point: &PathBuf) -> Result<(), String> {
+    Err("Linux FUSE-Provider: noch nicht implementiert".into())
+}
+
+pub fn populate(_mount_point: &PathBuf, _entries: &[RemoteEntry]) -> Result<(), String> {
+    Err("Linux FUSE-Provider: noch nicht implementiert".into())
+}

clients/desktop/src-tauri/src/cloud_files/mod.rs

@@ -0,0 +1,121 @@
+//! Native File-Provider-Integration (Platzhalter-Dateien wie bei OneDrive).
+//!
+//! Auf Windows realisiert ueber die Cloud Files API (cfapi.dll), auf Linux
+//! ueber FUSE (optional, hinter `linux_fuse`-Feature). macOS folgt spaeter
+//! ueber NSFileProviderExtension (braucht Apple-Signatur).
+//!
+//! Der bestehende `sync::engine` bleibt unberuehrt und bietet weiterhin
+//! den klassischen "kopiere-alles-lokal"-Modus. Der Cloud-Files-Modus
+//! ist sozusagen "files-on-demand": Datei wird erst bei Zugriff geladen.
+
+use serde::{Deserialize, Serialize};
+use std::path::PathBuf;
+
+/// Ein Eintrag aus dem Mini-Cloud-Syncbaum, so wie er vom Server kommt.
+/// Wird von beiden Plattformen genutzt, um Platzhalter / FUSE-Inodes zu
+/// erzeugen.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct RemoteEntry {
+    pub id: i64,
+    pub name: String,
+    pub parent_id: Option<i64>,
+    pub is_folder: bool,
+    pub size: i64,
+    /// UTC-ISO8601
+    pub modified_at: String,
+    /// SHA-256 falls vom Server ausgeliefert, sonst None.
+    pub checksum: Option<String>,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum SyncState {
+    /// Datei existiert nur als Platzhalter (online-only).
+    Cloud,
+    /// Datei ist vollstaendig lokal vorhanden und aktuell.
+    InSync,
+    /// Lokal geaendert, Upload ausstehend.
+    PendingUpload,
+    /// Auf dem Server gesperrt (durch anderen Nutzer).
+    LockedByOther,
+    /// Durch diesen Client gesperrt.
+    LockedLocal,
+}
+
+#[cfg(windows)]
+pub mod windows;
+#[cfg(windows)]
+pub mod shell_integration;
+#[cfg(all(target_os = "linux", feature = "linux_fuse"))]
+pub mod linux;
+pub mod sync_loop;
+pub mod watcher;
+
+/// Registriere den Sync-Root beim Betriebssystem. Ruft je nach Plattform
+/// cfapi/CfRegisterSyncRoot bzw. mountet ein FUSE-Dateisystem.
+#[allow(unused_variables)]
+pub fn register_sync_root(
+    mount_point: &PathBuf,
+    provider_name: &str,
+    account_id: &str,
+) -> Result<(), String> {
+    #[cfg(windows)]
+    return windows::register_sync_root(mount_point, provider_name, account_id);
+
+    #[cfg(all(target_os = "linux", feature = "linux_fuse"))]
+    return linux::mount(mount_point);
+
+    #[cfg(not(any(windows, all(target_os = "linux", feature = "linux_fuse"))))]
+    Err("File-Provider-Integration fuer diese Plattform noch nicht verfuegbar".into())
+}
+
+#[allow(unused_variables)]
+pub fn unregister_sync_root(mount_point: &PathBuf) -> Result<(), String> {
+    #[cfg(windows)]
+    return windows::unregister_sync_root(mount_point);
+
+    #[cfg(all(target_os = "linux", feature = "linux_fuse"))]
+    return linux::unmount(mount_point);
+
+    #[cfg(not(any(windows, all(target_os = "linux", feature = "linux_fuse"))))]
+    Err("File-Provider-Integration fuer diese Plattform noch nicht verfuegbar".into())
+}
+
+/// Erzeuge fuer alle Remote-Eintraege Platzhalter (cloud-only Dateien).
+/// Ordner werden als echte Verzeichnisse angelegt, Dateien als
+/// Platzhalter mit gespeicherten Metadaten (Groesse, Mtime, ID).
+#[allow(unused_variables)]
+pub fn populate_placeholders(
+    mount_point: &PathBuf,
+    entries: &[RemoteEntry],
+) -> Result<(), String> {
+    #[cfg(windows)]
+    return windows::populate_placeholders(mount_point, entries);
+
+    #[cfg(all(target_os = "linux", feature = "linux_fuse"))]
+    return linux::populate(mount_point, entries);
+
+    #[cfg(not(any(windows, all(target_os = "linux", feature = "linux_fuse"))))]
+    Err("File-Provider-Integration fuer diese Plattform noch nicht verfuegbar".into())
+}
+
+/// Ist File-Provider-Integration auf dieser Plattform grundsaetzlich verfuegbar?
+pub fn is_supported() -> bool {
+    cfg!(windows) || cfg!(all(target_os = "linux", feature = "linux_fuse"))
+}
+
+/// Markiere eine lokal bereits vorhandene Datei als "immer offline halten".
+#[allow(unused_variables)]
+pub fn pin_file(path: &PathBuf) -> Result<(), String> {
+    #[cfg(windows)]
+    return windows::set_pin_state(path, true);
+    #[cfg(not(windows))]
+    Err("Nur auf Windows unterstuetzt".into())
+}
+
+#[allow(unused_variables)]
+pub fn unpin_file(path: &PathBuf) -> Result<(), String> {
+    #[cfg(windows)]
+    return windows::set_pin_state(path, false);
+    #[cfg(not(windows))]
+    Err("Nur auf Windows unterstuetzt".into())
+}

clients/desktop/src-tauri/src/cloud_files/shell_integration.rs

@@ -0,0 +1,206 @@
+//! Explorer-Sidebar-Integration fuer Windows (ohne Admin-Rechte).
+//!
+//! Registriert den Sync-Ordner als Shell-Namespace-Extension unter
+//! HKEY_CURRENT_USER, sodass er mit eigenem Icon in der Navigation
+//! des Datei-Explorers erscheint (wie OneDrive/Dropbox).
+//!
+//! Anders als die eigentliche Cloud Files API ist das reine Registry-
+//! Kosmetik - der Ordner funktioniert auch ohne Sidebar-Eintrag,
+//! nur sieht man ihn dann nicht in der linken Leiste.
+
+#![cfg(windows)]
+
+use std::path::Path;
+use winreg::enums::*;
+use winreg::RegKey;
+
+// Stabile GUID fuer Mini-Cloud - gleiche wie in windows.rs als ProviderId.
+const CLSID_GUID: &str = "{4D696E69-436C-6F75-6444-7566667944AB}";
+
+// Standard-CLSID fuer "Generic Shell Folder Implementation".
+const SHELL_FOLDER_CLSID: &str = "{0E5AAE11-A475-4c5b-AB00-C66DE400274E}";
+
+/// Registriere den Mount-Ordner in der Explorer-Navigation.
+/// `icon_source`: Pfad zu ICO oder EXE mit Icon-Index (z.B. "C:\\app.exe,0")
+pub fn install(
+    display_name: &str,
+    mount_point: &Path,
+    icon_source: &str,
+) -> Result<(), String> {
+    let hkcu = RegKey::predef(HKEY_CURRENT_USER);
+
+    // 1) CLSID-Eintrag unter Software\Classes\CLSID\{GUID}
+    let clsid_path = format!("Software\\Classes\\CLSID\\{}", CLSID_GUID);
+    let (clsid, _) = hkcu
+        .create_subkey(&clsid_path)
+        .map_err(|e| format!("create CLSID: {e}"))?;
+    clsid
+        .set_value("", &display_name.to_string())
+        .map_err(|e| format!("set displayname: {e}"))?;
+    clsid
+        .set_value("System.IsPinnedToNameSpaceTree", &1u32)
+        .map_err(|e| format!("set pinned: {e}"))?;
+    clsid
+        .set_value("SortOrderIndex", &0x42u32)
+        .map_err(|e| format!("set sortorder: {e}"))?;
+
+    // 2) DefaultIcon
+    let (icon_key, _) = clsid
+        .create_subkey("DefaultIcon")
+        .map_err(|e| format!("create DefaultIcon: {e}"))?;
+    icon_key
+        .set_value("", &icon_source.to_string())
+        .map_err(|e| format!("set icon: {e}"))?;
+
+    // 3) InProcServer32 -> shell32.dll (Standard Shell-Folder-Host)
+    let (inproc, _) = clsid
+        .create_subkey("InProcServer32")
+        .map_err(|e| format!("create InProcServer32: {e}"))?;
+    inproc
+        .set_value("", &"%SystemRoot%\\system32\\shell32.dll".to_string())
+        .map_err(|e| format!("set shell32: {e}"))?;
+    inproc
+        .set_value("ThreadingModel", &"Both".to_string())
+        .map_err(|e| format!("set threading: {e}"))?;
+
+    // 4) Instance -> zeigt auf generischen Shell-Folder
+    let (instance, _) = clsid
+        .create_subkey("Instance")
+        .map_err(|e| format!("create Instance: {e}"))?;
+    instance
+        .set_value("CLSID", &SHELL_FOLDER_CLSID.to_string())
+        .map_err(|e| format!("set inst clsid: {e}"))?;
+
+    let (pb, _) = instance
+        .create_subkey("InitPropertyBag")
+        .map_err(|e| format!("create InitPropertyBag: {e}"))?;
+    pb.set_value("Attributes", &0x11u32)
+        .map_err(|e| format!("set attrs pb: {e}"))?;
+    pb.set_value(
+        "TargetFolderPath",
+        &mount_point.to_string_lossy().into_owned(),
+    )
+    .map_err(|e| format!("set target: {e}"))?;
+
+    // 5) ShellFolder-Flags
+    let (sf, _) = clsid
+        .create_subkey("ShellFolder")
+        .map_err(|e| format!("create ShellFolder: {e}"))?;
+    sf.set_value("FolderValueFlags", &0x28u32)
+        .map_err(|e| format!("set folderflags: {e}"))?;
+    sf.set_value("Attributes", &0xF080004Du32)
+        .map_err(|e| format!("set attrs sf: {e}"))?;
+
+    // 6) In die Navigation einhaengen
+    let ns_path = format!(
+        "Software\\Microsoft\\Windows\\CurrentVersion\\Explorer\\Desktop\\NameSpace\\{}",
+        CLSID_GUID
+    );
+    let (ns, _) = hkcu
+        .create_subkey(&ns_path)
+        .map_err(|e| format!("create NameSpace: {e}"))?;
+    ns.set_value("", &display_name.to_string())
+        .map_err(|e| format!("set ns name: {e}"))?;
+
+    // 7) Kontext-Menue-Verben (Rechtsklick) fuer Dateien unter dem Mount
+    install_context_menu(mount_point)?;
+
+    // 8) Explorer informieren (SHChangeNotify)
+    notify_shell();
+
+    Ok(())
+}
+
+/// Registriert "Immer offline halten" / "Speicher freigeben" als
+/// Rechtsklick-Menuepunkte, die nur fuer Dateien unterhalb des Mounts
+/// angezeigt werden (AppliesTo-Filter).
+fn install_context_menu(mount_point: &Path) -> Result<(), String> {
+    let hkcu = RegKey::predef(HKEY_CURRENT_USER);
+    let exe = std::env::current_exe()
+        .map_err(|e| format!("current_exe: {e}"))?
+        .to_string_lossy()
+        .into_owned();
+    // Trailing Backslash wegstrippen, dann eine saubere AQS-Query bauen.
+    // Registry-Werte sind normale Strings; Backslashes bleiben einfach.
+    let mount_clean = mount_point
+        .to_string_lossy()
+        .trim_end_matches('\\')
+        .to_string();
+    // AppliesTo: nur Dateien, deren Pfad mit dem Mount-Ordner beginnt.
+    let applies_to = format!("System.ItemPathDisplay:~< \"{}\"", mount_clean);
+
+    for (verb, label, flag) in [
+        ("MiniCloudPin", "Immer offline verfuegbar", "--pin"),
+        ("MiniCloudUnpin", "Speicher freigeben", "--unpin"),
+    ] {
+        // Unter AllFilesystemObjects statt * - das greift auch fuer
+        // Ordner und vermeidet Konflikte mit Dateityp-spezifischen Verben.
+        let key_path = format!("Software\\Classes\\AllFilesystemObjects\\shell\\{}", verb);
+        let (k, _) = hkcu
+            .create_subkey(&key_path)
+            .map_err(|e| format!("verb {verb}: {e}"))?;
+        k.set_value("", &label.to_string())
+            .map_err(|e| format!("default: {e}"))?;
+        k.set_value("MUIVerb", &label.to_string())
+            .map_err(|e| format!("MUIVerb: {e}"))?;
+        k.set_value("AppliesTo", &applies_to)
+            .map_err(|e| format!("AppliesTo: {e}"))?;
+        k.set_value("Icon", &exe)
+            .map_err(|e| format!("Icon: {e}"))?;
+
+        let (cmd, _) = k
+            .create_subkey("command")
+            .map_err(|e| format!("cmd: {e}"))?;
+        cmd.set_value("", &format!("\"{}\" {} \"%1\"", exe, flag))
+            .map_err(|e| format!("cmdline: {e}"))?;
+    }
+    Ok(())
+}
+
+fn uninstall_context_menu() {
+    let hkcu = RegKey::predef(HKEY_CURRENT_USER);
+    for verb in ["MiniCloudPin", "MiniCloudUnpin"] {
+        // alte (falsche) Stelle ebenfalls aufraeumen
+        let _ = hkcu.delete_subkey_all(format!("Software\\Classes\\*\\shell\\{}", verb));
+        let _ = hkcu.delete_subkey_all(format!(
+            "Software\\Classes\\AllFilesystemObjects\\shell\\{}",
+            verb
+        ));
+    }
+}
+
+/// Entferne die Shell-Integration wieder.
+pub fn uninstall() -> Result<(), String> {
+    let hkcu = RegKey::predef(HKEY_CURRENT_USER);
+
+    let ns_path = format!(
+        "Software\\Microsoft\\Windows\\CurrentVersion\\Explorer\\Desktop\\NameSpace\\{}",
+        CLSID_GUID
+    );
+    let _ = hkcu.delete_subkey_all(&ns_path);
+
+    let clsid_path = format!("Software\\Classes\\CLSID\\{}", CLSID_GUID);
+    let _ = hkcu.delete_subkey_all(&clsid_path);
+
+    uninstall_context_menu();
+
+    notify_shell();
+    Ok(())
+}
+
+/// Teilt Explorer mit, dass sich die Shell-Namespace-Liste geaendert hat.
+/// Ohne das sieht man den neuen Eintrag erst nach Explorer-Neustart.
+fn notify_shell() {
+    use windows::Win32::UI::Shell::{SHChangeNotify, SHCNE_ASSOCCHANGED, SHCNF_IDLIST};
+    unsafe {
+        SHChangeNotify(SHCNE_ASSOCCHANGED, SHCNF_IDLIST, None, None);
+    }
+}
+
+/// Standard-Icon-Quelle: die laufende .exe mit Index 0.
+pub fn default_icon_source() -> String {
+    std::env::current_exe()
+        .ok()
+        .and_then(|p| p.to_str().map(|s| format!("{},0", s)))
+        .unwrap_or_else(|| "%SystemRoot%\\system32\\imageres.dll,2".to_string())
+}

clients/desktop/src-tauri/src/cloud_files/sync_loop.rs

@@ -0,0 +1,221 @@
+//! Hintergrund-Synchronisation fuer den Cloud-Files-Modus.
+//!
+//! Zwei Aufgaben:
+//! 1. Lokale Aenderungen im Mount-Point beobachten (notify-Watcher) und
+//!    geaenderte Dateien hochladen. Neu angelegte Dateien werden als
+//!    neue Datei beim Server registriert und als Platzhalter markiert.
+//! 2. Serverseitige Aenderungen pollen (/api/sync/changes?since=...) und
+//!    fehlende Platzhalter erzeugen bzw. entfernte loeschen.
+//!
+//! Der Loop laeuft in einem dedizierten Tokio-Task; ein gespeicherter
+//! `Stop`-Channel beendet ihn sauber beim Deaktivieren.
+
+use super::RemoteEntry;
+use serde::Deserialize;
+use std::path::PathBuf;
+use std::sync::atomic::{AtomicBool, Ordering};
+use std::sync::Arc;
+use std::time::Duration;
+use tokio::sync::mpsc;
+
+#[derive(Clone)]
+pub struct SyncLoopConfig {
+    pub server_url: String,
+    pub access_token: String,
+    pub mount_point: PathBuf,
+    pub poll_interval_secs: u64,
+}
+
+pub struct SyncLoopHandle {
+    pub stop_flag: Arc<AtomicBool>,
+    pub tx: mpsc::UnboundedSender<LoopMessage>,
+}
+
+pub enum LoopMessage {
+    LocalChange(PathBuf),
+    Shutdown,
+}
+
+/// Starte den Sync-Loop. Gibt einen Handle zurueck, mit dem man ihn
+/// stoppen oder externe Events (z.B. vom Watcher) einspeisen kann.
+pub fn start(cfg: SyncLoopConfig) -> SyncLoopHandle {
+    let stop_flag = Arc::new(AtomicBool::new(false));
+    let (tx, mut rx) = mpsc::unbounded_channel::<LoopMessage>();
+    let stop = stop_flag.clone();
+    let cfg_task = cfg.clone();
+    tokio::spawn(async move {
+        let client = reqwest::Client::new();
+        let mut since: Option<String> = None;
+        let mut interval = tokio::time::interval(Duration::from_secs(cfg_task.poll_interval_secs));
+        loop {
+            if stop.load(Ordering::Relaxed) {
+                break;
+            }
+            tokio::select! {
+                _ = interval.tick() => {
+                    if let Err(e) = poll_server_changes(&client, &cfg_task, &mut since).await {
+                        eprintln!("[cloud_files] poll error: {e}");
+                    }
+                }
+                Some(msg) = rx.recv() => {
+                    match msg {
+                        LoopMessage::Shutdown => break,
+                        LoopMessage::LocalChange(path) => {
+                            if let Err(e) = upload_local_change(&client, &cfg_task, &path).await {
+                                eprintln!("[cloud_files] upload error: {e}");
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    });
+    SyncLoopHandle { stop_flag, tx }
+}
+
+#[derive(Debug, Deserialize)]
+struct ChangesResponse {
+    #[serde(default)]
+    created: Vec<RemoteEntry>,
+    #[serde(default)]
+    updated: Vec<RemoteEntry>,
+    #[serde(default)]
+    deleted: Vec<i64>,
+    timestamp: Option<String>,
+}
+
+async fn poll_server_changes(
+    client: &reqwest::Client,
+    cfg: &SyncLoopConfig,
+    since: &mut Option<String>,
+) -> Result<(), String> {
+    let base = cfg.server_url.trim_end_matches('/');
+    let mut url = format!("{}/api/sync/changes", base);
+    if let Some(s) = since.as_deref() {
+        url.push_str(&format!("?since={}", urlencode(s)));
+    }
+    let resp = client
+        .get(&url)
+        .bearer_auth(&cfg.access_token)
+        .send()
+        .await
+        .map_err(|e| e.to_string())?;
+    if !resp.status().is_success() {
+        return Err(format!("HTTP {}", resp.status()));
+    }
+    let body: ChangesResponse = resp.json().await.map_err(|e| e.to_string())?;
+
+    // Created + Updated: jeweils passendes Verzeichnis sichern, dann
+    // Platzhalter (neu) anlegen. Bei Updates muss der alte Platzhalter
+    // erst geloescht werden - Windows erlaubt kein "replace in place".
+    for e in body.created.iter().chain(body.updated.iter()) {
+        let rel = build_relative_path(e);
+        let full = cfg.mount_point.join(&rel);
+        if e.is_folder {
+            let _ = std::fs::create_dir_all(&full);
+            continue;
+        }
+        let parent = full.parent().map(|p| p.to_path_buf()).unwrap_or_else(|| cfg.mount_point.clone());
+        let _ = std::fs::create_dir_all(&parent);
+        let _ = std::fs::remove_file(&full); // ignoriert falls nicht da
+        #[cfg(windows)]
+        {
+            let identity = e.id.to_string();
+            if let Err(err) = super::windows::create_placeholder_at(
+                &parent,
+                &e.name,
+                e.size,
+                &e.modified_at,
+                identity.as_bytes(),
+            ) {
+                eprintln!("[cloud_files] placeholder {}: {}", e.name, err);
+            }
+        }
+    }
+
+    // Deleted: nur per ID vom Server - wir kennen den Pfad nicht mehr.
+    // MVP: ignorieren. In Version 2 fuehren wir ein lokales Mapping.
+    let _ = body.deleted;
+
+    if let Some(ts) = body.timestamp {
+        *since = Some(ts);
+    }
+    Ok(())
+}
+
+async fn upload_local_change(
+    client: &reqwest::Client,
+    cfg: &SyncLoopConfig,
+    path: &PathBuf,
+) -> Result<(), String> {
+    if !path.is_file() {
+        return Ok(());
+    }
+    // cfapi-Platzhalter oder gerade hydrierende Dateien NICHT hochladen -
+    // sonst wird jede Wolken-Datei sofort komplett gesynct und wir haben
+    // keinen On-Demand-Modus mehr.
+    #[cfg(windows)]
+    {
+        if super::windows::is_cfapi_placeholder(path) {
+            super::windows::log_msg(
+                &cfg.mount_point,
+                &format!("skip upload (placeholder): {}", path.display()),
+            );
+            return Ok(());
+        }
+    }
+    // Eigene Log-Datei nicht mit hochladen.
+    if path
+        .file_name()
+        .and_then(|n| n.to_str())
+        .map(|n| n.starts_with(".minicloud-"))
+        .unwrap_or(false)
+    {
+        return Ok(());
+    }
+    // Relativer Pfad im Mount = Ziel-Pfad auf Server
+    let rel = path
+        .strip_prefix(&cfg.mount_point)
+        .map_err(|_| "path outside mount".to_string())?
+        .to_string_lossy()
+        .replace('\\', "/");
+    let bytes = std::fs::read(path).map_err(|e| e.to_string())?;
+    let base = cfg.server_url.trim_end_matches('/');
+    let url = format!("{}/api/files/upload", base);
+    let file_name = path
+        .file_name()
+        .and_then(|s| s.to_str())
+        .unwrap_or("unnamed")
+        .to_string();
+    let form = reqwest::multipart::Form::new()
+        .text("path", rel.clone())
+        .part(
+            "file",
+            reqwest::multipart::Part::bytes(bytes).file_name(file_name),
+        );
+    let resp = client
+        .post(&url)
+        .bearer_auth(&cfg.access_token)
+        .multipart(form)
+        .send()
+        .await
+        .map_err(|e| e.to_string())?;
+    if !resp.status().is_success() {
+        return Err(format!("HTTP {}", resp.status()));
+    }
+    Ok(())
+}
+
+fn build_relative_path(e: &RemoteEntry) -> PathBuf {
+    // Achtung: RemoteEntry hat nur parent_id, nicht den kompletten Pfad.
+    // Fuer diesen einfachen Fall nehmen wir nur den Namen. Bei geschachtelten
+    // Ordnern muesste man die Hierarchie ueber /api/sync/tree vor-laden -
+    // das passiert einmal beim Aktivieren; Delta-Updates kommen meistens
+    // flach (oder in einer gemeinsamen Wurzel).
+    PathBuf::from(&e.name)
+}
+
+fn urlencode(s: &str) -> String {
+    // Sehr minimalistisch: wir ersetzen nur problematische Zeichen.
+    s.replace(' ', "%20").replace(':', "%3A").replace('+', "%2B")
+}

clients/desktop/src-tauri/src/cloud_files/watcher.rs

@@ -0,0 +1,43 @@
+//! Leichtgewichtiger Callback-basierter FS-Watcher fuer den Cloud-Files-Modus.
+//!
+//! Anders als `sync::watcher::FileWatcher` gibt dieser hier einen Closure
+//! direkt an notify weiter, sodass wir kein Channel-Pumpen brauchen.
+
+use notify::{Event, EventKind, RecommendedWatcher, RecursiveMode, Watcher, Config};
+use std::path::{Path, PathBuf};
+
+pub struct CallbackWatcher {
+    _watcher: RecommendedWatcher,
+}
+
+impl CallbackWatcher {
+    pub fn new<F>(watch_dir: &Path, mut on_change: F) -> Result<Self, String>
+    where
+        F: FnMut(PathBuf, EventKind) + Send + 'static,
+    {
+        let mut watcher = RecommendedWatcher::new(
+            move |res: Result<Event, notify::Error>| {
+                if let Ok(ev) = res {
+                    for path in ev.paths {
+                        let name = path.file_name().and_then(|n| n.to_str()).unwrap_or("");
+                        if name.starts_with('.')
+                            || name.starts_with('~')
+                            || name.ends_with(".tmp")
+                        {
+                            continue;
+                        }
+                        on_change(path, ev.kind.clone());
+                    }
+                }
+            },
+            Config::default(),
+        )
+        .map_err(|e| format!("Watcher-Fehler: {e}"))?;
+
+        watcher
+            .watch(watch_dir, RecursiveMode::Recursive)
+            .map_err(|e| format!("Watch-Fehler: {e}"))?;
+
+        Ok(Self { _watcher: watcher })
+    }
+}

clients/desktop/src-tauri/src/cloud_files/windows.rs

@@ -0,0 +1,639 @@
+//! Windows Cloud Files API Integration.
+//!
+//! Registriert den Sync-Ordner als Sync-Root, legt Platzhalter-Dateien an
+//! und reicht Zugriffe auf Dateidaten als HTTPS-Download durch. Der
+//! Explorer zeigt Wolken-/Haken-Overlays automatisch an, solange die
+//! Pin-Stati korrekt gesetzt sind.
+//!
+//! Voraussetzung: Windows 10 1709+ (cfapi.dll). Der Account-Identifier
+//! sollte stabil sein (z.B. Hash(Server-URL + Username)).
+
+#![cfg(windows)]
+
+use super::RemoteEntry;
+use once_cell::sync::Lazy;
+use std::path::{Path, PathBuf};
+use std::ptr;
+use std::sync::{Arc, Mutex};
+use widestring::U16CString;
+
+use windows::core::PCWSTR;
+use windows::Win32::Storage::CloudFilters as CF;
+use windows::Win32::Storage::FileSystem::FILE_ATTRIBUTE_NORMAL;
+use windows::Win32::System::Com::{CoInitializeEx, COINIT_MULTITHREADED};
+
+#[derive(Default, Clone)]
+pub struct CloudContext {
+    pub server_url: String,
+    pub access_token: String,
+    pub mount_point: PathBuf,
+}
+
+static CONTEXT: Lazy<Arc<Mutex<CloudContext>>> =
+    Lazy::new(|| Arc::new(Mutex::new(CloudContext::default())));
+
+static CONNECTION_KEY: Lazy<Mutex<Option<CF::CF_CONNECTION_KEY>>> =
+    Lazy::new(|| Mutex::new(None));
+
+pub fn set_context(server_url: String, access_token: String, mount_point: PathBuf) {
+    let mut ctx = CONTEXT.lock().unwrap();
+    ctx.server_url = server_url;
+    ctx.access_token = access_token;
+    ctx.mount_point = mount_point;
+}
+
+fn ctx_snapshot() -> CloudContext {
+    CONTEXT.lock().unwrap().clone()
+}
+
+const PROVIDER_VERSION: &str = "1.0";
+
+// Windows-FILETIME: 100ns-Ticks seit 1601-01-01. Unix-Epoch liegt
+// 11_644_473_600 Sekunden danach.
+fn unix_to_ft_ticks(unix_secs: i64) -> i64 {
+    (unix_secs + 11_644_473_600) * 10_000_000
+}
+
+// ---------------------------------------------------------------------------
+// Sync-Root-Registrierung
+// ---------------------------------------------------------------------------
+
+pub fn register_sync_root(
+    mount_point: &PathBuf,
+    provider_name: &str,
+    account_id: &str,
+) -> Result<(), String> {
+    // COM initialisieren (cfapi benoetigt MTA-Apartment)
+    unsafe {
+        let _ = CoInitializeEx(Some(ptr::null()), COINIT_MULTITHREADED);
+    }
+
+    std::fs::create_dir_all(mount_point).map_err(|e| format!("mkdir: {e}"))?;
+
+    let display = format!("Mini-Cloud - {}", account_id);
+    let path_wide = U16CString::from_str(mount_point.to_string_lossy().as_ref())
+        .map_err(|e| format!("path encode: {e}"))?;
+    let display_wide = U16CString::from_str(&display).map_err(|e| e.to_string())?;
+    let provider_wide = U16CString::from_str(provider_name).map_err(|e| e.to_string())?;
+    let version_wide = U16CString::from_str(PROVIDER_VERSION).map_err(|e| e.to_string())?;
+
+    let mut info = CF::CF_SYNC_REGISTRATION::default();
+    info.StructSize = std::mem::size_of::<CF::CF_SYNC_REGISTRATION>() as u32;
+    info.ProviderName = PCWSTR(provider_wide.as_ptr());
+    info.ProviderVersion = PCWSTR(version_wide.as_ptr());
+    // Stabile GUID fuer "Mini-Cloud" (random einmalig generiert).
+    info.ProviderId = windows::core::GUID::from_u128(0x4D696E69_436C_6F75_6444_7566667944ab);
+
+    let mut policies = CF::CF_SYNC_POLICIES::default();
+    policies.StructSize = std::mem::size_of::<CF::CF_SYNC_POLICIES>() as u32;
+    policies.HardLink = CF::CF_HARDLINK_POLICY::default();
+    policies.Hydration = CF::CF_HYDRATION_POLICY::default();
+    policies.Population = CF::CF_POPULATION_POLICY::default();
+    policies.InSync = CF::CF_INSYNC_POLICY::default();
+
+    // Hydration PARTIAL = Datei-Inhalt kommt bei Zugriff per FETCH_DATA.
+    // Population FULL = Ordnerinhalt ist komplett vorgefuellt durch uns
+    // (populate_placeholders). So muss Windows NICHT FETCH_PLACEHOLDERS
+    // callen, den wir nicht implementieren - sonst timeout beim Oeffnen.
+    policies.Hydration.Primary = CF::CF_HYDRATION_POLICY_PARTIAL;
+    policies.Population.Primary = CF::CF_POPULATION_POLICY_FULL;
+
+    // Holder fuer displayname, damit wir ihn spaeter ggf. in ein eigenes
+    // struct einbauen koennen. windows-rs verlangt hier nichts weiter.
+    let _ = display_wide;
+
+    // Erst eine eventuell vorhandene Registrierung wegraeumen. Sonst
+    // uebernimmt UPDATE nur einen Teil der Policies und alte PARTIAL-
+    // Population-Einstellungen bleiben aktiv -> Explorer-Timeout.
+    unsafe {
+        let _ = CF::CfUnregisterSyncRoot(PCWSTR(path_wide.as_ptr()));
+    }
+
+    log_msg(mount_point, &format!(
+        "register_sync_root path={} provider={} account={}",
+        mount_point.display(), provider_name, account_id
+    ));
+
+    unsafe {
+        if let Err(e) = CF::CfRegisterSyncRoot(
+            PCWSTR(path_wide.as_ptr()),
+            &info,
+            &policies,
+            CF::CF_REGISTER_FLAG_NONE,
+        ) {
+            log_err(mount_point, &format!("CfRegisterSyncRoot FAILED: {e:?}"));
+            // Als Fallback mit UPDATE-Flag
+            CF::CfRegisterSyncRoot(
+                PCWSTR(path_wide.as_ptr()),
+                &info,
+                &policies,
+                CF::CF_REGISTER_FLAG_UPDATE,
+            )
+            .map_err(|e| format!("CfRegisterSyncRoot(UPDATE): {e}"))?;
+        }
+    }
+
+    log_msg(mount_point, "CfRegisterSyncRoot OK");
+    connect_callbacks(mount_point)?;
+    log_msg(mount_point, "callbacks connected");
+
+    // Explorer-Sidebar-Eintrag mit Wolken-Icon
+    let icon = super::shell_integration::default_icon_source();
+    match super::shell_integration::install(provider_name, mount_point, &icon) {
+        Ok(()) => log_msg(mount_point, "shell integration installed"),
+        Err(e) => log_err(mount_point, &format!("shell integration FAILED: {e}")),
+    }
+
+    Ok(())
+}
+
+pub fn unregister_sync_root(mount_point: &PathBuf) -> Result<(), String> {
+    // Shell-Eintrag zuerst entfernen (schlaegt nie fehl).
+    let _ = super::shell_integration::uninstall();
+
+    let _ = disconnect_callbacks();
+    let path_wide = U16CString::from_str(mount_point.to_string_lossy().as_ref())
+        .map_err(|e| e.to_string())?;
+    unsafe {
+        CF::CfUnregisterSyncRoot(PCWSTR(path_wide.as_ptr()))
+            .map_err(|e| format!("CfUnregisterSyncRoot: {e}"))?;
+    }
+    Ok(())
+}
+
+// ---------------------------------------------------------------------------
+// Callback-Tabelle
+// ---------------------------------------------------------------------------
+
+unsafe extern "system" fn on_fetch_data(
+    info: *const CF::CF_CALLBACK_INFO,
+    params: *const CF::CF_CALLBACK_PARAMETERS,
+) {
+    let info = &*info;
+    let params = &*params;
+    let fetch = &params.Anonymous.FetchData;
+
+    // FileIdentity enthaelt unsere Mini-Cloud-File-ID als UTF-8-Bytes.
+    let identity = std::slice::from_raw_parts(
+        info.FileIdentity as *const u8,
+        info.FileIdentityLength as usize,
+    );
+    let file_id: i64 = std::str::from_utf8(identity)
+        .ok()
+        .and_then(|s| s.parse().ok())
+        .unwrap_or(0);
+
+    let offset: i64 = fetch.RequiredFileOffset;
+    let length: u64 = fetch.RequiredLength as u64;
+    let connection_key = info.ConnectionKey;
+    let transfer_key = info.TransferKey;
+
+    // HTTPS-Download im separaten Thread (Callback darf nicht blockieren).
+    let ctx = ctx_snapshot();
+    std::thread::spawn(move || {
+        log_msg(&ctx.mount_point, &format!(
+            "FETCH_DATA file_id={file_id} offset={offset} len={length}"
+        ));
+        match transfer_range(connection_key, transfer_key, file_id, offset, length, &ctx) {
+            Ok(()) => log_msg(&ctx.mount_point, &format!(
+                "fetch file_id={file_id} OK"
+            )),
+            Err(e) => {
+                log_err(&ctx.mount_point, &format!(
+                    "fetch file_id={file_id} offset={offset} len={length} FAILED: {e}"
+                ));
+                // Garantiert Fehler-Completion, damit Windows nicht in Timeout laeuft.
+                let _ = complete_transfer(connection_key, transfer_key, None, offset, length);
+            }
+        }
+    });
+}
+
+pub fn log_msg(mount: &Path, msg: &str) {
+    use std::io::Write;
+    // Log-Datei NEBEN den Mount, damit sie nicht selbst als Platzhalter
+    // behandelt wird.
+    let log = mount
+        .parent()
+        .map(|p| p.join(".minicloud-cloudfiles.log"))
+        .unwrap_or_else(|| PathBuf::from(".minicloud-cloudfiles.log"));
+    if let Ok(mut f) = std::fs::OpenOptions::new().create(true).append(true).open(&log) {
+        let _ = writeln!(f, "[{}] {}", chrono::Utc::now().to_rfc3339(), msg);
+    }
+}
+
+fn log_err(mount: &Path, msg: &str) {
+    log_msg(mount, msg);
+}
+
+/// True wenn die Datei ein cfapi-Platzhalter ist (noch nicht hydriert)
+/// oder gerade vom Cloud-Filter verwaltet wird. Fuer solche Dateien
+/// duerfen wir KEINEN Upload ausloesen, sonst verwandelt der Sync-Loop
+/// jeden Platzhalter sofort in eine vollstaendig lokale Datei.
+pub fn is_cfapi_placeholder(path: &Path) -> bool {
+    use windows::Win32::Storage::FileSystem::GetFileAttributesW;
+    let Ok(w) = U16CString::from_str(path.to_string_lossy().as_ref()) else {
+        return false;
+    };
+    let attrs = unsafe { GetFileAttributesW(PCWSTR(w.as_ptr())) };
+    if attrs == u32::MAX {
+        return false;
+    }
+    // FILE_ATTRIBUTE_OFFLINE (0x1000) oder
+    // FILE_ATTRIBUTE_RECALL_ON_DATA_ACCESS (0x400000) oder
+    // FILE_ATTRIBUTE_RECALL_ON_OPEN (0x40000)
+    (attrs & 0x0040_1000) != 0 || (attrs & 0x0004_0000) != 0
+}
+
+fn transfer_range(
+    connection_key: CF::CF_CONNECTION_KEY,
+    transfer_key: i64,
+    file_id: i64,
+    offset: i64,
+    length: u64,
+    ctx: &CloudContext,
+) -> Result<(), String> {
+    if ctx.server_url.is_empty() || ctx.access_token.is_empty() {
+        return Err("CloudContext nicht gesetzt (Server/Token leer)".into());
+    }
+    let client = reqwest::blocking::Client::builder()
+        .timeout(std::time::Duration::from_secs(60))
+        .build()
+        .map_err(|e| format!("client: {e}"))?;
+    let url = format!(
+        "{}/api/files/{}/download",
+        ctx.server_url.trim_end_matches('/'),
+        file_id
+    );
+    let range = format!("bytes={}-{}", offset, offset as u64 + length - 1);
+    let resp = client
+        .get(&url)
+        .bearer_auth(&ctx.access_token)
+        .header("Range", &range)
+        .send()
+        .map_err(|e| format!("send: {e}"))?;
+    let status = resp.status();
+    if !status.is_success() && status.as_u16() != 206 {
+        return Err(format!("HTTP {}", status));
+    }
+    let bytes = resp.bytes().map_err(|e: reqwest::Error| e.to_string())?;
+    // Wenn Server kein Range unterstuetzt und volle Datei liefert,
+    // aus dem Body den angeforderten Bereich ausschneiden.
+    let slice: &[u8] = if status.as_u16() == 206 {
+        &bytes[..]
+    } else {
+        let start = offset as usize;
+        let end = (start + length as usize).min(bytes.len());
+        if start >= bytes.len() {
+            &[]
+        } else {
+            &bytes[start..end]
+        }
+    };
+    complete_transfer(connection_key, transfer_key, Some(slice), offset, slice.len() as u64)
+}
+
+fn complete_transfer(
+    connection_key: CF::CF_CONNECTION_KEY,
+    transfer_key: i64,
+    data: Option<&[u8]>,
+    offset: i64,
+    length: u64,
+) -> Result<(), String> {
+    let mut op_info = CF::CF_OPERATION_INFO::default();
+    op_info.StructSize = std::mem::size_of::<CF::CF_OPERATION_INFO>() as u32;
+    op_info.Type = CF::CF_OPERATION_TYPE_TRANSFER_DATA;
+    op_info.ConnectionKey = connection_key;
+    op_info.TransferKey = transfer_key;
+
+    let mut params = CF::CF_OPERATION_PARAMETERS::default();
+    params.ParamSize = std::mem::size_of::<CF::CF_OPERATION_PARAMETERS>() as u32;
+
+    unsafe {
+        let transfer = &mut params.Anonymous.TransferData;
+        if let Some(data) = data {
+            transfer.CompletionStatus = windows::Win32::Foundation::NTSTATUS(0); // STATUS_SUCCESS
+            transfer.Buffer = data.as_ptr() as _;
+            transfer.Offset = offset;
+            transfer.Length = length as i64;
+        } else {
+            transfer.CompletionStatus =
+                windows::Win32::Foundation::NTSTATUS(0xC0000001u32 as i32); // STATUS_UNSUCCESSFUL
+        }
+
+        CF::CfExecute(&op_info, &mut params).map_err(|e| format!("CfExecute: {e}"))?;
+    }
+    Ok(())
+}
+
+unsafe extern "system" fn on_fetch_placeholders(
+    info: *const CF::CF_CALLBACK_INFO,
+    _params: *const CF::CF_CALLBACK_PARAMETERS,
+) {
+    // Safety-Net: wir populieren schon ueber populate_placeholders,
+    // aber falls Windows trotzdem ruft, geben wir leere Antwort.
+    let info = &*info;
+    let mut op_info = CF::CF_OPERATION_INFO::default();
+    op_info.StructSize = std::mem::size_of::<CF::CF_OPERATION_INFO>() as u32;
+    op_info.Type = CF::CF_OPERATION_TYPE_TRANSFER_PLACEHOLDERS;
+    op_info.ConnectionKey = info.ConnectionKey;
+    op_info.TransferKey = info.TransferKey;
+    let mut params = CF::CF_OPERATION_PARAMETERS::default();
+    params.ParamSize = std::mem::size_of::<CF::CF_OPERATION_PARAMETERS>() as u32;
+    let transfer = &mut params.Anonymous.TransferPlaceholders;
+    transfer.CompletionStatus = windows::Win32::Foundation::NTSTATUS(0);
+    transfer.PlaceholderTotalCount = 0;
+    transfer.PlaceholderArray = std::ptr::null_mut();
+    transfer.PlaceholderCount = 0;
+    transfer.EntriesProcessed = 0;
+    transfer.Flags = CF::CF_OPERATION_TRANSFER_PLACEHOLDERS_FLAG_DISABLE_ON_DEMAND_POPULATION;
+    let _ = CF::CfExecute(&op_info, &mut params);
+}
+
+fn connect_callbacks(mount_point: &Path) -> Result<(), String> {
+    let callbacks = [
+        CF::CF_CALLBACK_REGISTRATION {
+            Type: CF::CF_CALLBACK_TYPE_FETCH_DATA,
+            Callback: Some(on_fetch_data),
+        },
+        CF::CF_CALLBACK_REGISTRATION {
+            Type: CF::CF_CALLBACK_TYPE_FETCH_PLACEHOLDERS,
+            Callback: Some(on_fetch_placeholders),
+        },
+        // Sentinel: Type = INVALID beendet die Tabelle.
+        CF::CF_CALLBACK_REGISTRATION {
+            Type: CF::CF_CALLBACK_TYPE_NONE,
+            Callback: None,
+        },
+    ];
+
+    let path_wide = U16CString::from_str(mount_point.to_string_lossy().as_ref())
+        .map_err(|e| e.to_string())?;
+
+    let key = unsafe {
+        CF::CfConnectSyncRoot(
+            PCWSTR(path_wide.as_ptr()),
+            callbacks.as_ptr(),
+            None,
+            CF::CF_CONNECT_FLAG_REQUIRE_PROCESS_INFO
+                | CF::CF_CONNECT_FLAG_REQUIRE_FULL_FILE_PATH,
+        )
+        .map_err(|e| format!("CfConnectSyncRoot: {e}"))?
+    };
+    *CONNECTION_KEY.lock().unwrap() = Some(key);
+    Ok(())
+}
+
+fn disconnect_callbacks() -> Result<(), String> {
+    if let Some(key) = CONNECTION_KEY.lock().unwrap().take() {
+        unsafe {
+            CF::CfDisconnectSyncRoot(key)
+                .map_err(|e| format!("CfDisconnectSyncRoot: {e}"))?;
+        }
+    }
+    Ok(())
+}
+
+// ---------------------------------------------------------------------------
+// Placeholder-Erzeugung
+// ---------------------------------------------------------------------------
+
+pub fn populate_placeholders(
+    mount_point: &PathBuf,
+    entries: &[RemoteEntry],
+) -> Result<(), String> {
+    use std::collections::HashMap;
+    log_msg(mount_point, &format!(
+        "populate_placeholders: {} Eintraege", entries.len()
+    ));
+    let by_id: HashMap<i64, &RemoteEntry> = entries.iter().map(|e| (e.id, e)).collect();
+
+    fn rel_path<'a>(
+        entry: &'a RemoteEntry,
+        by_id: &HashMap<i64, &'a RemoteEntry>,
+    ) -> PathBuf {
+        let mut parts = vec![entry.name.as_str()];
+        let mut cur = entry.parent_id;
+        while let Some(id) = cur {
+            if let Some(p) = by_id.get(&id) {
+                parts.push(p.name.as_str());
+                cur = p.parent_id;
+            } else {
+                break;
+            }
+        }
+        parts.reverse();
+        parts.iter().collect()
+    }
+
+    // Erst Ordner anlegen
+    for e in entries.iter().filter(|e| e.is_folder) {
+        let p = mount_point.join(rel_path(e, &by_id));
+        std::fs::create_dir_all(&p).ok();
+    }
+
+    // Dann Dateien als Platzhalter. Existierende "normale" Dateien
+    // (z.B. nach vorherigem CfUnregisterSyncRoot) vorher loeschen,
+    // weil CfCreatePlaceholders sonst mit ERROR_FILE_EXISTS scheitert
+    // und die Datei nie zum Platzhalter wird -> spaeter koennte man
+    // sie nicht mehr dehydrieren (0x80070178 "keine Clouddatei").
+    for e in entries.iter().filter(|e| !e.is_folder) {
+        let rel = rel_path(e, &by_id);
+        let full = mount_point.join(&rel);
+        let parent = rel
+            .parent()
+            .map(|p| mount_point.join(p))
+            .unwrap_or_else(|| mount_point.clone());
+        let identity = e.id.to_string();
+
+        if full.exists() && !is_cfapi_placeholder(&full) {
+            log_msg(mount_point, &format!(
+                "deleting non-placeholder {} to recreate",
+                full.display()
+            ));
+            if let Err(err) = std::fs::remove_file(&full) {
+                log_err(mount_point, &format!(
+                    "remove {} failed: {err}", full.display()
+                ));
+            }
+        }
+
+        match create_placeholder(&parent, &e.name, e.size, &e.modified_at, identity.as_bytes()) {
+            Ok(()) => log_msg(mount_point, &format!("placeholder created: {}", full.display())),
+            Err(err) => log_err(mount_point, &format!(
+                "placeholder {} FAILED: {err}", full.display()
+            )),
+        }
+    }
+    Ok(())
+}
+
+pub fn create_placeholder_at(
+    parent_dir: &Path,
+    name: &str,
+    size: i64,
+    modified_iso: &str,
+    file_identity: &[u8],
+) -> Result<(), String> {
+    create_placeholder(parent_dir, name, size, modified_iso, file_identity)
+}
+
+fn create_placeholder(
+    parent_dir: &Path,
+    name: &str,
+    size: i64,
+    modified_iso: &str,
+    file_identity: &[u8],
+) -> Result<(), String> {
+    let parent_wide = U16CString::from_str(parent_dir.to_string_lossy().as_ref())
+        .map_err(|e| e.to_string())?;
+    let name_wide = U16CString::from_str(name).map_err(|e| e.to_string())?;
+
+    let mtime_unix = chrono::DateTime::parse_from_rfc3339(modified_iso)
+        .map(|dt| dt.timestamp())
+        .unwrap_or(0);
+    let ft_ticks = unix_to_ft_ticks(mtime_unix);
+
+    let mut ph = CF::CF_PLACEHOLDER_CREATE_INFO::default();
+    ph.RelativeFileName = PCWSTR(name_wide.as_ptr());
+    ph.FsMetadata.FileSize = size;
+    ph.FsMetadata.BasicInfo.FileAttributes = FILE_ATTRIBUTE_NORMAL.0;
+    ph.FsMetadata.BasicInfo.LastWriteTime = ft_ticks;
+    ph.FsMetadata.BasicInfo.CreationTime = ft_ticks;
+    ph.FsMetadata.BasicInfo.ChangeTime = ft_ticks;
+    ph.FsMetadata.BasicInfo.LastAccessTime = ft_ticks;
+    ph.Flags = CF::CF_PLACEHOLDER_CREATE_FLAG_MARK_IN_SYNC;
+    ph.FileIdentity = file_identity.as_ptr() as _;
+    ph.FileIdentityLength = file_identity.len() as u32;
+
+    // CfCreatePlaceholders nimmt in windows-rs 0.58 einen Slice und einen
+    // Option<*mut u32> fuer "wie viele wurden angelegt".
+    let mut phs = [ph];
+    let mut count: u32 = 0;
+    unsafe {
+        CF::CfCreatePlaceholders(
+            PCWSTR(parent_wide.as_ptr()),
+            &mut phs,
+            CF::CF_CREATE_FLAG_NONE,
+            Some(&mut count as *mut u32),
+        )
+        .map_err(|e| format!("CfCreatePlaceholders: {e}"))?;
+    }
+    Ok(())
+}
+
+// ---------------------------------------------------------------------------
+// Pin / Unpin (offline halten)
+// ---------------------------------------------------------------------------
+
+pub fn set_pin_state(file: &Path, pinned: bool) -> Result<(), String> {
+    use windows::Win32::Storage::FileSystem::{
+        CreateFileW, FILE_FLAG_BACKUP_SEMANTICS, FILE_FLAG_OPEN_REPARSE_POINT,
+        FILE_WRITE_ATTRIBUTES, FILE_READ_ATTRIBUTES,
+        FILE_SHARE_READ, FILE_SHARE_WRITE, FILE_SHARE_DELETE, OPEN_EXISTING,
+    };
+
+    let path_wide = U16CString::from_str(file.to_string_lossy().as_ref())
+        .map_err(|e| e.to_string())?;
+    // CfSetPinState / CfDehydratePlaceholder brauchen WRITE_ATTRIBUTES.
+    // OPEN_REPARSE_POINT verhindert, dass das Oeffnen selbst eine
+    // Hydration ausloest (sonst waere Unpin bedeutungslos).
+    let handle = unsafe {
+        CreateFileW(
+            PCWSTR(path_wide.as_ptr()),
+            (FILE_READ_ATTRIBUTES | FILE_WRITE_ATTRIBUTES).0,
+            FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
+            None,
+            OPEN_EXISTING,
+            FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_OPEN_REPARSE_POINT,
+            None,
+        )
+    }
+    .map_err(|e| format!("open: {e}"))?;
+
+    let state = if pinned {
+        CF::CF_PIN_STATE_PINNED
+    } else {
+        CF::CF_PIN_STATE_UNPINNED
+    };
+    let set_res = unsafe {
+        CF::CfSetPinState(handle, state, CF::CF_SET_PIN_FLAG_NONE, None)
+    };
+
+    // Hydrate bei Pin / Dehydrate bei Unpin. CfSetPinState aendert nur
+    // das Flag - ohne explizite Hydrate-/Dehydrate-Calls passiert am
+    // Disk-Inhalt und am Icon nichts Sichtbares.
+    let (hydrate_err, dehydrate_err) = if set_res.is_ok() {
+        if pinned {
+            let r = unsafe {
+                CF::CfHydratePlaceholder(
+                    handle,
+                    0,
+                    -1,
+                    CF::CF_HYDRATE_FLAG_NONE,
+                    None,
+                )
+            };
+            (r.err().map(|e| format!("{:?}", e)), None)
+        } else {
+            let r = unsafe {
+                CF::CfDehydratePlaceholder(
+                    handle,
+                    0,
+                    -1,
+                    CF::CF_DEHYDRATE_FLAG_NONE,
+                    None,
+                )
+            };
+            (None, r.err().map(|e| format!("{:?}", e)))
+        }
+    } else {
+        (None, None)
+    };
+
+    unsafe {
+        let _ = windows::Win32::Foundation::CloseHandle(handle);
+    }
+
+    // Explorer Icon-Overlay aktualisieren
+    notify_file_update(file);
+
+    // Log-Verzeichnis ist der Mount-Ordner oder dessen Parent
+    let log_dir = file
+        .ancestors()
+        .find(|p| p.parent().is_some())
+        .map(|p| p.to_path_buf())
+        .unwrap_or_else(|| file.to_path_buf());
+    log_msg(
+        &log_dir,
+        &format!(
+            "set_pin_state file={} pinned={} result={:?} hydrate_err={:?} dehydrate_err={:?}",
+            file.display(),
+            pinned,
+            set_res,
+            hydrate_err,
+            dehydrate_err
+        ),
+    );
+
+    set_res.map_err(|e| format!("CfSetPinState: {e}"))?;
+    Ok(())
+}
+
+/// Sagt dem Shell "diese Datei hat sich geaendert" damit das Overlay-
+/// Icon (Wolke/Haken) aktualisiert wird, ohne dass der User F5 druecken
+/// muss.
+fn notify_file_update(file: &Path) {
+    use windows::Win32::UI::Shell::{SHChangeNotify, SHCNE_UPDATEITEM, SHCNF_PATHW};
+    let Ok(w) = U16CString::from_str(file.to_string_lossy().as_ref()) else {
+        return;
+    };
+    unsafe {
+        SHChangeNotify(
+            SHCNE_UPDATEITEM,
+            SHCNF_PATHW,
+            Some(w.as_ptr() as _),
+            None,
+        );
+    }
+}

clients/desktop/src-tauri/src/main.rs

@@ -0,0 +1,6 @@
+// Prevents additional console window on Windows in release, DO NOT REMOVE!!
+#![cfg_attr(not(debug_assertions), windows_subsystem = "windows")]
+
+fn main() {
+    minicloud_sync_lib::run()
+}

clients/desktop/src-tauri/src/sync/api.rs

@@ -0,0 +1,277 @@
+use reqwest::Client;
+use serde::{Deserialize, Serialize};
+use std::path::Path;
+
+#[derive(Clone)]
+pub struct MiniCloudApi {
+    client: Client,
+    pub server_url: String,
+    pub access_token: String,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone)]
+pub struct LoginResponse {
+    pub access_token: String,
+    pub user: UserInfo,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone)]
+pub struct UserInfo {
+    pub id: i64,
+    pub username: String,
+    pub role: String,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone)]
+pub struct FileEntry {
+    pub id: i64,
+    pub name: String,
+    pub is_folder: bool,
+    pub size: Option<i64>,
+    pub checksum: Option<String>,
+    pub updated_at: Option<String>,
+    pub children: Option<Vec<FileEntry>>,
+    pub locked: Option<bool>,
+    pub locked_by: Option<String>,
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+pub struct SyncTreeResponse {
+    pub tree: Vec<FileEntry>,
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+#[allow(dead_code)]
+pub struct SyncChangesResponse {
+    pub changes: Vec<FileEntry>,
+    pub server_time: String,
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+#[allow(dead_code)]
+pub struct LockResponse {
+    pub locked: Option<bool>,
+    pub locked_by: Option<String>,
+    pub error: Option<String>,
+}
+
+impl MiniCloudApi {
+    pub fn new(server_url: &str) -> Self {
+        Self {
+            client: Client::builder()
+                .danger_accept_invalid_certs(false)
+                .build()
+                .unwrap(),
+            server_url: server_url.trim_end_matches('/').to_string(),
+            access_token: String::new(),
+        }
+    }
+
+    fn auth_header(&self) -> String {
+        format!("Bearer {}", self.access_token)
+    }
+
+    pub async fn login(&mut self, username: &str, password: &str) -> Result<LoginResponse, String> {
+        let url = format!("{}/api/auth/login", self.server_url);
+        let body = serde_json::json!({
+            "username": username,
+            "password": password,
+        });
+
+        let resp = self.client.post(&url)
+            .json(&body)
+            .send()
+            .await
+            .map_err(|e| format!("Verbindungsfehler: {}", e))?;
+
+        if !resp.status().is_success() {
+            let text = resp.text().await.unwrap_or_default();
+            return Err(format!("Login fehlgeschlagen: {}", text));
+        }
+
+        let data: LoginResponse = resp.json().await
+            .map_err(|e| format!("Antwort-Fehler: {}", e))?;
+        self.access_token = data.access_token.clone();
+        Ok(data)
+    }
+
+    pub async fn refresh_token(&mut self) -> Result<String, String> {
+        let url = format!("{}/api/auth/refresh", self.server_url);
+        let resp = self.client.post(&url)
+            .header("Authorization", self.auth_header())
+            .send()
+            .await
+            .map_err(|e| format!("Refresh fehlgeschlagen: {}", e))?;
+
+        if !resp.status().is_success() {
+            return Err("Token-Refresh fehlgeschlagen".to_string());
+        }
+
+        let data: serde_json::Value = resp.json().await.map_err(|e| e.to_string())?;
+        if let Some(token) = data.get("access_token").and_then(|t| t.as_str()) {
+            self.access_token = token.to_string();
+            Ok(token.to_string())
+        } else {
+            Err("Kein Token in Antwort".to_string())
+        }
+    }
+
+    pub async fn get_sync_tree(&self) -> Result<Vec<FileEntry>, String> {
+        let url = format!("{}/api/sync/tree", self.server_url);
+        let resp = self.client.get(&url)
+            .header("Authorization", self.auth_header())
+            .send()
+            .await
+            .map_err(|e| format!("Sync-Tree Fehler: {}", e))?;
+
+        if !resp.status().is_success() {
+            let status = resp.status();
+            let text = resp.text().await.unwrap_or_default();
+            return Err(format!("Sync-Tree HTTP {}: {}", status, text));
+        }
+        let data: SyncTreeResponse = resp.json().await
+            .map_err(|e| format!("Sync-Tree Parse-Fehler: {}", e))?;
+        Ok(data.tree)
+    }
+
+    #[allow(dead_code)]
+    pub async fn get_changes(&self, since: &str) -> Result<SyncChangesResponse, String> {
+        let url = format!("{}/api/sync/changes?since={}", self.server_url, since);
+        let resp = self.client.get(&url)
+            .header("Authorization", self.auth_header())
+            .send()
+            .await
+            .map_err(|e| format!("Changes Fehler: {}", e))?;
+
+        resp.json().await.map_err(|e| format!("Parse-Fehler: {}", e))
+    }
+
+    pub async fn download_file(&self, file_id: i64, dest: &Path) -> Result<(), String> {
+        let url = format!("{}/api/files/{}/download?token={}",
+            self.server_url, file_id, self.access_token);
+        let resp = self.client.get(&url)
+            .send()
+            .await
+            .map_err(|e| format!("Download Fehler: {}", e))?;
+
+        if !resp.status().is_success() {
+            return Err(format!("Download fehlgeschlagen: {}", resp.status()));
+        }
+
+        let bytes = resp.bytes().await.map_err(|e| e.to_string())?;
+        if let Some(parent) = dest.parent() {
+            std::fs::create_dir_all(parent).map_err(|e| e.to_string())?;
+        }
+        std::fs::write(dest, &bytes).map_err(|e| format!("Schreiben fehlgeschlagen: {}", e))
+    }
+
+    pub async fn upload_file(&self, file_path: &Path, parent_id: Option<i64>) -> Result<FileEntry, String> {
+        let url = format!("{}/api/files/upload", self.server_url);
+        let file_name = file_path.file_name()
+            .and_then(|n| n.to_str())
+            .unwrap_or("file")
+            .to_string();
+
+        let file_bytes = std::fs::read(file_path)
+            .map_err(|e| format!("Datei lesen fehlgeschlagen: {}", e))?;
+
+        let mut form = reqwest::multipart::Form::new()
+            .part("file", reqwest::multipart::Part::bytes(file_bytes).file_name(file_name));
+
+        if let Some(pid) = parent_id {
+            form = form.text("parent_id", pid.to_string());
+        }
+
+        let resp = self.client.post(&url)
+            .header("Authorization", self.auth_header())
+            .multipart(form)
+            .send()
+            .await
+            .map_err(|e| format!("Upload Fehler: {}", e))?;
+
+        if !resp.status().is_success() {
+            let text = resp.text().await.unwrap_or_default();
+            return Err(format!("Upload fehlgeschlagen: {}", text));
+        }
+
+        resp.json().await.map_err(|e| format!("Parse-Fehler: {}", e))
+    }
+
+    pub async fn create_folder(&self, name: &str, parent_id: Option<i64>) -> Result<FileEntry, String> {
+        let url = format!("{}/api/files/folder", self.server_url);
+        let body = serde_json::json!({
+            "name": name,
+            "parent_id": parent_id,
+        });
+
+        let resp = self.client.post(&url)
+            .header("Authorization", self.auth_header())
+            .json(&body)
+            .send()
+            .await
+            .map_err(|e| format!("Create-Folder Verbindungsfehler: {}", e))?;
+
+        if !resp.status().is_success() {
+            let status = resp.status();
+            let text = resp.text().await.unwrap_or_default();
+            return Err(format!("Create-Folder fehlgeschlagen ({}): {}", status, text));
+        }
+        resp.json().await.map_err(|e| format!("Create-Folder Parse-Fehler: {}", e))
+    }
+
+    pub async fn lock_file(&self, file_id: i64, client_info: &str) -> Result<(), String> {
+        let url = format!("{}/api/files/{}/lock", self.server_url, file_id);
+        let body = serde_json::json!({ "client_info": client_info });
+
+        let resp = self.client.post(&url)
+            .header("Authorization", self.auth_header())
+            .json(&body)
+            .send()
+            .await
+            .map_err(|e| e.to_string())?;
+
+        if resp.status().as_u16() == 423 {
+            let data: serde_json::Value = resp.json().await.map_err(|e| e.to_string())?;
+            let by = data.get("locked_by").and_then(|v| v.as_str()).unwrap_or("?");
+            return Err(format!("Datei gesperrt von {}", by));
+        }
+        if !resp.status().is_success() {
+            return Err("Lock fehlgeschlagen".to_string());
+        }
+        Ok(())
+    }
+
+    pub async fn unlock_file(&self, file_id: i64) -> Result<(), String> {
+        let url = format!("{}/api/files/{}/unlock", self.server_url, file_id);
+        self.client.post(&url)
+            .header("Authorization", self.auth_header())
+            .send()
+            .await
+            .map_err(|e| e.to_string())?;
+        Ok(())
+    }
+
+    pub async fn delete_file(&self, file_id: i64) -> Result<(), String> {
+        let url = format!("{}/api/files/{}", self.server_url, file_id);
+        let resp = self.client.delete(&url)
+            .header("Authorization", self.auth_header())
+            .send()
+            .await
+            .map_err(|e| format!("Delete Fehler: {}", e))?;
+        if !resp.status().is_success() {
+            let text = resp.text().await.unwrap_or_default();
+            return Err(format!("Delete fehlgeschlagen: {}", text));
+        }
+        Ok(())
+    }
+
+    pub async fn heartbeat(&self, file_id: i64) -> Result<(), String> {
+        let url = format!("{}/api/files/{}/heartbeat", self.server_url, file_id);
+        self.client.post(&url)
+            .header("Authorization", self.auth_header())
+            .send()
+            .await
+            .map_err(|e| e.to_string())?;
+        Ok(())
+    }
+}

clients/desktop/src-tauri/src/sync/config.rs

@@ -0,0 +1,82 @@
+use crate::sync::engine::SyncPath;
+use serde::{Deserialize, Serialize};
+use std::path::PathBuf;
+
+#[derive(Debug, Clone, Serialize, Deserialize, Default)]
+pub struct AppConfig {
+    pub server_url: String,
+    pub username: String,
+    #[serde(default)]
+    pub password_b64: String, // base64 encoded (not plaintext in JSON)
+    pub sync_paths: Vec<SyncPath>,
+    #[serde(default)]
+    pub auto_start: bool,
+    #[serde(default)]
+    pub start_minimized: bool,
+    /// Persistierter Mount-Punkt der Cloud-Files-Integration.
+    /// Leer = nicht aktiv. Wird beim App-Start wieder aktiviert.
+    #[serde(default)]
+    pub cloud_files_mount: String,
+}
+
+impl AppConfig {
+    /// Get the config directory
+    fn config_dir() -> PathBuf {
+        // Windows: %APPDATA%/MiniCloud Sync
+        // Linux: ~/.config/MiniCloud Sync
+        // Mac: ~/Library/Application Support/MiniCloud Sync
+        let base = dirs::config_dir()
+            .or_else(|| dirs::home_dir().map(|h| h.join(".config")))
+            .unwrap_or_else(|| PathBuf::from("."));
+        let dir = base.join("MiniCloud Sync");
+        std::fs::create_dir_all(&dir).ok();
+        dir
+    }
+
+    fn config_path() -> PathBuf {
+        Self::config_dir().join("config.json")
+    }
+
+    pub fn load() -> Self {
+        let path = Self::config_path();
+        eprintln!("[Config] Loading from: {}", path.display());
+        if path.exists() {
+            match std::fs::read_to_string(&path) {
+                Ok(content) => {
+                    match serde_json::from_str(&content) {
+                        Ok(config) => {
+                            eprintln!("[Config] Loaded OK");
+                            return config;
+                        }
+                        Err(e) => eprintln!("[Config] Parse error: {}", e),
+                    }
+                }
+                Err(e) => eprintln!("[Config] Read error: {}", e),
+            }
+        } else {
+            eprintln!("[Config] No config file found");
+        }
+        Self::default()
+    }
+
+    pub fn save(&self) -> Result<(), String> {
+        let path = Self::config_path();
+        eprintln!("[Config] Saving to: {}", path.display());
+        let json = serde_json::to_string_pretty(self).map_err(|e| e.to_string())?;
+        std::fs::write(&path, &json).map_err(|e| format!("Config save: {}", e))?;
+        eprintln!("[Config] Saved OK");
+        Ok(())
+    }
+
+    pub fn save_password(&mut self, password: &str) {
+        use base64::Engine;
+        self.password_b64 = base64::engine::general_purpose::STANDARD.encode(password.as_bytes());
+    }
+
+    pub fn get_password(&self) -> Option<String> {
+        if self.password_b64.is_empty() { return None; }
+        use base64::Engine;
+        let bytes = base64::engine::general_purpose::STANDARD.decode(&self.password_b64).ok()?;
+        String::from_utf8(bytes).ok()
+    }
+}

clients/desktop/src-tauri/src/sync/engine.rs

@@ -0,0 +1,487 @@
+use crate::sync::api::{FileEntry, MiniCloudApi};
+use crate::sync::journal::{Journal, JournalEntry};
+use sha2::{Digest, Sha256};
+use serde::{Deserialize, Serialize};
+use std::path::{Path, PathBuf};
+use std::sync::Arc;
+
+/// A configured sync path: maps a server folder to a local folder.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct SyncPath {
+    pub id: String,
+    pub server_path: String,
+    pub server_folder_id: Option<i64>,
+    pub local_dir: String,
+    pub mode: SyncMode,
+    pub enabled: bool,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
+pub enum SyncMode {
+    Virtual,
+    Full,
+}
+
+/// `.cloud` placeholder content (JSON payload of the 0-byte-ish placeholder).
+#[derive(Debug, Serialize, Deserialize)]
+struct CloudPlaceholder {
+    id: i64,
+    name: String,
+    size: i64,
+    checksum: String,
+    updated_at: String,
+    server_path: String,
+}
+
+pub struct SyncEngine {
+    pub api: MiniCloudApi,
+    pub sync_paths: Vec<SyncPath>,
+    pub journal: Arc<Journal>,
+    pub username: String,
+}
+
+impl SyncEngine {
+    pub fn new(api: MiniCloudApi, journal: Arc<Journal>, username: String) -> Self {
+        Self { api, sync_paths: Vec::new(), journal, username }
+    }
+
+    /// Sync every configured path.
+    pub async fn sync_all(&mut self) -> Result<Vec<String>, String> {
+        let mut log = Vec::new();
+        let tree = self.api.get_sync_tree().await?;
+        let sync_paths = self.sync_paths.clone();
+
+        for sp in &sync_paths {
+            if !sp.enabled { continue; }
+            let local_dir = PathBuf::from(&sp.local_dir);
+            std::fs::create_dir_all(&local_dir).ok();
+
+            let subtree = match sp.server_folder_id {
+                Some(id) => find_subtree(&tree, id).unwrap_or_default(),
+                None => tree.clone(),
+            };
+
+            // Phase 1: propagate deletions based on journal history.
+            self.detect_deletions(sp, &subtree, &local_dir, &mut log).await;
+
+            // Phase 2: normal sync (downloads, uploads, conflicts).
+            self.sync_dir(&subtree, &local_dir, "", sp.server_folder_id, sp, &mut log).await;
+        }
+        Ok(log)
+    }
+
+    /// Walks the journal for this sync path and reconciles existence:
+    ///   - file was in journal and is gone locally but still on server  -> delete on server
+    ///   - file was in journal and is gone on server but still local    -> delete locally
+    ///   - file is gone on both sides                                   -> clean journal entry
+    async fn detect_deletions(
+        &self,
+        sp: &SyncPath,
+        subtree: &[FileEntry],
+        local_root: &Path,
+        log: &mut Vec<String>,
+    ) {
+        use std::collections::HashMap;
+        let mut server_files: HashMap<String, i64> = HashMap::new();
+        collect_server_files(subtree, "", &mut server_files);
+
+        for je in self.journal.list_for_sync(&sp.id) {
+            let local_real = local_root.join(&je.relative_path);
+            let local_cloud = {
+                let parent = local_real.parent().map(|p| p.to_path_buf());
+                let fname = local_real.file_name().map(|n| n.to_string_lossy().to_string());
+                match (parent, fname) {
+                    (Some(p), Some(n)) => p.join(format!("{}.cloud", n)),
+                    _ => PathBuf::new(),
+                }
+            };
+            let local_exists = local_real.exists() || local_cloud.exists();
+            let server_id = server_files.get(&je.relative_path).copied();
+
+            match (local_exists, server_id) {
+                (true, Some(_)) => { /* present on both sides - normal sync handles it */ }
+                (false, None) => {
+                    let _ = self.journal.delete(&sp.id, &je.relative_path);
+                }
+                (false, Some(id)) => {
+                    match self.api.delete_file(id).await {
+                        Ok(_) => {
+                            log.push(format!("Server-Papierkorb: {}", je.relative_path));
+                            let _ = self.journal.delete(&sp.id, &je.relative_path);
+                        }
+                        Err(e) => log.push(format!("Server-Delete-Fehler {}: {}", je.relative_path, e)),
+                    }
+                }
+                (true, None) => {
+                    std::fs::remove_file(&local_real).ok();
+                    std::fs::remove_file(&local_cloud).ok();
+                    let _ = self.journal.delete(&sp.id, &je.relative_path);
+                    log.push(format!("Lokal geloescht: {}", je.relative_path));
+                }
+            }
+        }
+    }
+
+    /// Recursively sync a single directory level.
+    /// `rel_prefix` is the journal-relative path prefix (e.g. "", or "sub/dir/").
+    async fn sync_dir(
+        &mut self,
+        server_entries: &[FileEntry],
+        local_dir: &Path,
+        rel_prefix: &str,
+        parent_id: Option<i64>,
+        sp: &SyncPath,
+        log: &mut Vec<String>,
+    ) {
+        use std::collections::HashMap;
+
+        let server_by_name: HashMap<String, &FileEntry> = server_entries
+            .iter().map(|e| (e.name.clone(), e)).collect();
+
+        // --- Pass 1: iterate server entries, reconcile each against local/journal ---
+        for entry in server_entries {
+            let rel = if rel_prefix.is_empty() {
+                entry.name.clone()
+            } else {
+                format!("{}/{}", rel_prefix, entry.name)
+            };
+
+            if entry.is_folder {
+                let sub_local = local_dir.join(&entry.name);
+                std::fs::create_dir_all(&sub_local).ok();
+                if let Some(children) = &entry.children {
+                    Box::pin(self.sync_dir(children, &sub_local, &rel, Some(entry.id), sp, log)).await;
+                }
+                continue;
+            }
+
+            self.reconcile_file(entry, local_dir, &rel, parent_id, sp, log).await;
+        }
+
+        // --- Pass 2: iterate local entries, upload new local files/folders ---
+        let dir_iter = match std::fs::read_dir(local_dir) {
+            Ok(d) => d,
+            Err(_) => return,
+        };
+
+        for e in dir_iter.flatten() {
+            let name = e.file_name().to_string_lossy().to_string();
+            if should_skip_name(&name) { continue; }
+
+            let path = e.path();
+            let is_dir = path.is_dir();
+            // `.cloud` placeholders are stored locally under "foo.txt.cloud"
+            // but represent the server-side "foo.txt".
+            let real_name = name.trim_end_matches(".cloud").to_string();
+            let is_placeholder = name.ends_with(".cloud") && !is_dir;
+
+            // Already covered by server pass?
+            if server_by_name.contains_key(&real_name) { continue; }
+            if is_placeholder { continue; } // orphan placeholder - handled below
+
+            let rel = if rel_prefix.is_empty() {
+                real_name.clone()
+            } else {
+                format!("{}/{}", rel_prefix, real_name)
+            };
+
+            if is_dir {
+                match self.api.create_folder(&real_name, parent_id).await {
+                    Ok(folder) => {
+                        log.push(format!("Ordner erstellt: {}", rel));
+                        self.upload_local_tree(&path, Some(folder.id), &rel, sp, log).await;
+                    }
+                    Err(e) => log.push(format!("Ordner-Fehler {}: {}", rel, e)),
+                }
+            } else {
+                match self.api.upload_file(&path, parent_id).await {
+                    Ok(fe) => {
+                        log.push(format!("Hochgeladen: {}", rel));
+                        let checksum = fe.checksum.unwrap_or_default();
+                        let size = fe.size.unwrap_or(0);
+                        let _ = self.journal.upsert(&JournalEntry {
+                            sync_path_id: sp.id.clone(),
+                            relative_path: rel.clone(),
+                            file_id: Some(fe.id),
+                            synced_checksum: checksum,
+                            synced_size: size,
+                            synced_mtime: fe.updated_at.unwrap_or_default(),
+                            local_state: "offline".to_string(),
+                        });
+                    }
+                    Err(e) => log.push(format!("Upload-Fehler {}: {}", rel, e)),
+                }
+            }
+        }
+
+        // --- Pass 3: clean up orphan .cloud placeholders for files gone from server ---
+        if let Ok(dir_iter) = std::fs::read_dir(local_dir) {
+            for e in dir_iter.flatten() {
+                let name = e.file_name().to_string_lossy().to_string();
+                if !name.ends_with(".cloud") || e.path().is_dir() { continue; }
+                let real_name = name.trim_end_matches(".cloud");
+                if server_by_name.contains_key(real_name) { continue; }
+                std::fs::remove_file(e.path()).ok();
+                let rel = if rel_prefix.is_empty() {
+                    real_name.to_string()
+                } else {
+                    format!("{}/{}", rel_prefix, real_name)
+                };
+                let _ = self.journal.delete(&sp.id, &rel);
+                log.push(format!("Entfernt (Server): {}", name));
+            }
+        }
+    }
+
+    /// Core 3-way reconciliation for a single server file.
+    async fn reconcile_file(
+        &self,
+        entry: &FileEntry,
+        local_dir: &Path,
+        rel: &str,
+        parent_id: Option<i64>,
+        sp: &SyncPath,
+        log: &mut Vec<String>,
+    ) {
+        let real_path = local_dir.join(&entry.name);
+        let cloud_path = local_dir.join(format!("{}.cloud", entry.name));
+        let journal_entry = self.journal.get(&sp.id, rel);
+        let server_hash = entry.checksum.clone().unwrap_or_default();
+        let server_size = entry.size.unwrap_or(0);
+        let server_mtime = entry.updated_at.clone().unwrap_or_default();
+
+        // Case A: real file exists locally = offline state
+        if real_path.exists() && !real_path.is_dir() {
+            // Avoid race: if placeholder still around, remove it
+            if cloud_path.exists() { std::fs::remove_file(&cloud_path).ok(); }
+
+            let local_hash = compute_file_hash(&real_path);
+
+            if local_hash == server_hash {
+                // In sync - just (re)record journal
+                self.journal_offline(sp, rel, entry, &server_hash, server_size, &server_mtime);
+                return;
+            }
+
+            // Hashes differ. Locked by someone else? Hold back.
+            if entry.locked.unwrap_or(false) {
+                let by = entry.locked_by.clone().unwrap_or_default();
+                if by != self.username {
+                    log.push(format!("Zurueckgehalten (gesperrt von {}): {}", by, rel));
+                    return;
+                }
+            }
+
+            let (local_changed, server_changed) = match &journal_entry {
+                Some(j) => (local_hash != j.synced_checksum, server_hash != j.synced_checksum),
+                None => {
+                    // No journal history: this is the first time we're tracking
+                    // this file. Treat the server as authoritative (Nextcloud
+                    // does the same on first sync) so edits made on the web
+                    // GUI or other clients propagate down cleanly.
+                    (false, true)
+                }
+            };
+
+            if local_changed && !server_changed {
+                // Upload
+                match self.api.upload_file(&real_path, parent_id).await {
+                    Ok(fe) => {
+                        log.push(format!("Lokal->Server: {}", rel));
+                        let new_hash = fe.checksum.unwrap_or(local_hash.clone());
+                        self.journal_offline(sp, rel, entry, &new_hash,
+                            fe.size.unwrap_or(server_size),
+                            &fe.updated_at.unwrap_or(server_mtime.clone()));
+                    }
+                    Err(e) => log.push(format!("Upload-Fehler {}: {}", rel, e)),
+                }
+            } else if server_changed && !local_changed {
+                // Download
+                match self.api.download_file(entry.id, &real_path).await {
+                    Ok(_) => {
+                        log.push(format!("Server->Lokal: {}", rel));
+                        self.journal_offline(sp, rel, entry, &server_hash, server_size, &server_mtime);
+                    }
+                    Err(e) => log.push(format!("Download-Fehler {}: {}", rel, e)),
+                }
+            } else {
+                // Both changed OR no journal -> conflict copy
+                let conflict_path = make_conflict_path(&real_path, &self.username);
+                std::fs::rename(&real_path, &conflict_path).ok();
+                match self.api.download_file(entry.id, &real_path).await {
+                    Ok(_) => {
+                        log.push(format!("KONFLIKT: {} (lokal: {})", rel,
+                            conflict_path.file_name().unwrap().to_string_lossy()));
+                        self.journal_offline(sp, rel, entry, &server_hash, server_size, &server_mtime);
+                    }
+                    Err(e) => {
+                        // Restore original
+                        std::fs::rename(&conflict_path, &real_path).ok();
+                        log.push(format!("Download-Fehler {}: {}", rel, e));
+                    }
+                }
+            }
+            return;
+        }
+
+        // Case B: local has a .cloud placeholder (or neither) = virtual state
+        // Virtual placeholders never have local edits, just keep them fresh.
+        let needs_write = match std::fs::read_to_string(&cloud_path) {
+            Ok(content) => match serde_json::from_str::<CloudPlaceholder>(&content) {
+                Ok(old) => old.checksum != server_hash || old.id != entry.id,
+                Err(_) => true,
+            },
+            Err(_) => true,
+        };
+
+        if needs_write {
+            let placeholder = CloudPlaceholder {
+                id: entry.id,
+                name: entry.name.clone(),
+                size: server_size,
+                checksum: server_hash.clone(),
+                updated_at: server_mtime.clone(),
+                server_path: rel.to_string(),
+            };
+            if let Ok(json) = serde_json::to_string_pretty(&placeholder) {
+                if !cloud_path.exists() {
+                    log.push(format!("Platzhalter: {}.cloud", entry.name));
+                } else {
+                    log.push(format!("Platzhalter aktualisiert: {}.cloud", entry.name));
+                }
+                std::fs::write(&cloud_path, json).ok();
+            }
+        }
+
+        self.journal.upsert(&JournalEntry {
+            sync_path_id: sp.id.clone(),
+            relative_path: rel.to_string(),
+            file_id: Some(entry.id),
+            synced_checksum: server_hash,
+            synced_size: server_size,
+            synced_mtime: server_mtime,
+            local_state: "virtual".to_string(),
+        }).ok();
+
+        // If Full mode and no real file yet, download now
+        if sp.mode == SyncMode::Full && !real_path.exists() {
+            if let Err(e) = self.api.download_file(entry.id, &real_path).await {
+                log.push(format!("Full-Download-Fehler {}: {}", rel, e));
+            } else {
+                std::fs::remove_file(&cloud_path).ok();
+                log.push(format!("Heruntergeladen: {}", rel));
+                // Update journal to offline
+                if let Some(mut j) = self.journal.get(&sp.id, rel) {
+                    j.local_state = "offline".to_string();
+                    let _ = self.journal.upsert(&j);
+                }
+            }
+        }
+    }
+
+    fn journal_offline(
+        &self, sp: &SyncPath, rel: &str, entry: &FileEntry,
+        hash: &str, size: i64, mtime: &str,
+    ) {
+        let _ = self.journal.upsert(&JournalEntry {
+            sync_path_id: sp.id.clone(),
+            relative_path: rel.to_string(),
+            file_id: Some(entry.id),
+            synced_checksum: hash.to_string(),
+            synced_size: size,
+            synced_mtime: mtime.to_string(),
+            local_state: "offline".to_string(),
+        });
+    }
+
+    /// Walk a freshly-created local tree and upload every file (used after
+    /// creating a new folder on the server).
+    async fn upload_local_tree(
+        &self, dir: &Path, parent_id: Option<i64>, rel_prefix: &str,
+        sp: &SyncPath, log: &mut Vec<String>,
+    ) {
+        let iter = match std::fs::read_dir(dir) { Ok(d) => d, Err(_) => return };
+        for e in iter.flatten() {
+            let name = e.file_name().to_string_lossy().to_string();
+            if should_skip_name(&name) { continue; }
+            let path = e.path();
+            let rel = format!("{}/{}", rel_prefix, name);
+            if path.is_dir() {
+                match self.api.create_folder(&name, parent_id).await {
+                    Ok(folder) => {
+                        log.push(format!("Ordner erstellt: {}", rel));
+                        Box::pin(self.upload_local_tree(&path, Some(folder.id), &rel, sp, log)).await;
+                    }
+                    Err(e) => log.push(format!("Ordner-Fehler {}: {}", rel, e)),
+                }
+            } else {
+                match self.api.upload_file(&path, parent_id).await {
+                    Ok(fe) => {
+                        log.push(format!("Hochgeladen: {}", rel));
+                        self.journal_offline(sp, &rel, &fe,
+                            &fe.checksum.clone().unwrap_or_default(),
+                            fe.size.unwrap_or(0),
+                            &fe.updated_at.clone().unwrap_or_default());
+                    }
+                    Err(e) => log.push(format!("Upload-Fehler {}: {}", rel, e)),
+                }
+            }
+        }
+    }
+}
+
+fn should_skip_name(name: &str) -> bool {
+    name.starts_with('.') || name.starts_with('~') || name.ends_with(".tmp")
+}
+
+fn make_conflict_path(original: &Path, username: &str) -> PathBuf {
+    let stem = original.file_stem().map(|s| s.to_string_lossy().to_string()).unwrap_or_default();
+    let ext = original.extension().map(|e| e.to_string_lossy().to_string());
+    let ts = chrono::Local::now().format("%Y-%m-%d %H%M%S").to_string();
+    let name = match ext {
+        Some(e) if !e.is_empty() => format!("{} (Konflikt {} {}).{}", stem, username, ts, e),
+        _ => format!("{} (Konflikt {} {})", stem, username, ts),
+    };
+    original.parent().map(|p| p.join(&name)).unwrap_or_else(|| PathBuf::from(&name))
+}
+
+fn collect_server_files(
+    entries: &[FileEntry],
+    prefix: &str,
+    out: &mut std::collections::HashMap<String, i64>,
+) {
+    for e in entries {
+        let rel = if prefix.is_empty() {
+            e.name.clone()
+        } else {
+            format!("{}/{}", prefix, e.name)
+        };
+        if e.is_folder {
+            if let Some(children) = &e.children {
+                collect_server_files(children, &rel, out);
+            }
+        } else {
+            out.insert(rel, e.id);
+        }
+    }
+}
+
+fn find_subtree(tree: &[FileEntry], folder_id: i64) -> Option<Vec<FileEntry>> {
+    for entry in tree {
+        if entry.id == folder_id { return entry.children.clone(); }
+        if let Some(children) = &entry.children {
+            if let Some(r) = find_subtree(children, folder_id) { return Some(r); }
+        }
+    }
+    None
+}
+
+pub fn compute_file_hash(path: &Path) -> String {
+    let data = match std::fs::read(path) {
+        Ok(d) => d,
+        Err(_) => return String::new(),
+    };
+    let mut hasher = Sha256::new();
+    hasher.update(&data);
+    format!("{:x}", hasher.finalize())
+}

clients/desktop/src-tauri/src/sync/journal.rs

@@ -0,0 +1,120 @@
+use rusqlite::{params, Connection};
+use std::path::PathBuf;
+use std::sync::Mutex;
+
+/// One row of the sync journal. Represents the "last known synced state"
+/// for a single file within a sync path. The server and local checksum
+/// matched this value at the last successful sync.
+#[derive(Debug, Clone)]
+pub struct JournalEntry {
+    pub sync_path_id: String,
+    pub relative_path: String,
+    pub file_id: Option<i64>,
+    pub synced_checksum: String,
+    pub synced_size: i64,
+    pub synced_mtime: String,
+    pub local_state: String, // "virtual" or "offline"
+}
+
+pub struct Journal {
+    conn: Mutex<Connection>,
+}
+
+impl Journal {
+    pub fn open() -> Result<Self, String> {
+        let dir = dirs::config_dir()
+            .or_else(|| dirs::home_dir().map(|h| h.join(".config")))
+            .unwrap_or_else(|| PathBuf::from("."))
+            .join("MiniCloud Sync");
+        std::fs::create_dir_all(&dir).ok();
+        let path = dir.join("journal.db");
+        let conn = Connection::open(&path).map_err(|e| format!("Journal open: {}", e))?;
+
+        conn.execute_batch(
+            r#"
+            CREATE TABLE IF NOT EXISTS sync_journal (
+                sync_path_id   TEXT NOT NULL,
+                relative_path  TEXT NOT NULL,
+                file_id        INTEGER,
+                synced_checksum TEXT NOT NULL DEFAULT '',
+                synced_size    INTEGER NOT NULL DEFAULT 0,
+                synced_mtime   TEXT NOT NULL DEFAULT '',
+                local_state    TEXT NOT NULL DEFAULT 'virtual',
+                PRIMARY KEY (sync_path_id, relative_path)
+            );
+            "#,
+        ).map_err(|e| format!("Journal schema: {}", e))?;
+
+        Ok(Self { conn: Mutex::new(conn) })
+    }
+
+    pub fn get(&self, sync_path_id: &str, rel: &str) -> Option<JournalEntry> {
+        let conn = self.conn.lock().unwrap();
+        conn.query_row(
+            "SELECT file_id, synced_checksum, synced_size, synced_mtime, local_state
+             FROM sync_journal WHERE sync_path_id = ?1 AND relative_path = ?2",
+            params![sync_path_id, rel],
+            |row| Ok(JournalEntry {
+                sync_path_id: sync_path_id.to_string(),
+                relative_path: rel.to_string(),
+                file_id: row.get(0)?,
+                synced_checksum: row.get(1)?,
+                synced_size: row.get(2)?,
+                synced_mtime: row.get(3)?,
+                local_state: row.get(4)?,
+            }),
+        ).ok()
+    }
+
+    pub fn upsert(&self, e: &JournalEntry) -> Result<(), String> {
+        let conn = self.conn.lock().unwrap();
+        conn.execute(
+            "INSERT INTO sync_journal
+               (sync_path_id, relative_path, file_id, synced_checksum, synced_size, synced_mtime, local_state)
+             VALUES (?1, ?2, ?3, ?4, ?5, ?6, ?7)
+             ON CONFLICT(sync_path_id, relative_path) DO UPDATE SET
+               file_id = excluded.file_id,
+               synced_checksum = excluded.synced_checksum,
+               synced_size = excluded.synced_size,
+               synced_mtime = excluded.synced_mtime,
+               local_state = excluded.local_state",
+            params![e.sync_path_id, e.relative_path, e.file_id, e.synced_checksum,
+                    e.synced_size, e.synced_mtime, e.local_state],
+        ).map_err(|e| format!("Journal upsert: {}", e))?;
+        Ok(())
+    }
+
+    pub fn delete(&self, sync_path_id: &str, rel: &str) -> Result<(), String> {
+        let conn = self.conn.lock().unwrap();
+        conn.execute(
+            "DELETE FROM sync_journal WHERE sync_path_id = ?1 AND relative_path = ?2",
+            params![sync_path_id, rel],
+        ).map_err(|e| format!("Journal delete: {}", e))?;
+        Ok(())
+    }
+
+    pub fn list_for_sync(&self, sync_path_id: &str) -> Vec<JournalEntry> {
+        let conn = self.conn.lock().unwrap();
+        let mut stmt = match conn.prepare(
+            "SELECT relative_path, file_id, synced_checksum, synced_size, synced_mtime, local_state
+             FROM sync_journal WHERE sync_path_id = ?1") {
+            Ok(s) => s,
+            Err(_) => return Vec::new(),
+        };
+        let rows = stmt.query_map(params![sync_path_id], |row| {
+            Ok(JournalEntry {
+                sync_path_id: sync_path_id.to_string(),
+                relative_path: row.get(0)?,
+                file_id: row.get(1)?,
+                synced_checksum: row.get(2)?,
+                synced_size: row.get(3)?,
+                synced_mtime: row.get(4)?,
+                local_state: row.get(5)?,
+            })
+        });
+        match rows {
+            Ok(it) => it.filter_map(|r| r.ok()).collect(),
+            Err(_) => Vec::new(),
+        }
+    }
+}

clients/desktop/src-tauri/src/sync/mod.rs

@@ -0,0 +1,5 @@
+pub mod api;
+pub mod config;
+pub mod engine;
+pub mod journal;
+pub mod watcher;

clients/desktop/src-tauri/src/sync/watcher.rs

@@ -0,0 +1,59 @@
+use notify::{Config, Event, EventKind, RecommendedWatcher, RecursiveMode, Watcher};
+use std::path::PathBuf;
+use std::sync::mpsc;
+
+pub struct FileWatcher {
+    _watcher: RecommendedWatcher,
+    pub receiver: mpsc::Receiver<FileChange>,
+    pub path: PathBuf,
+}
+
+#[derive(Debug, Clone)]
+pub struct FileChange {
+    pub path: PathBuf,
+    pub kind: ChangeKind,
+}
+
+#[derive(Debug, Clone)]
+pub enum ChangeKind {
+    Created,
+    Modified,
+    Deleted,
+}
+
+impl FileWatcher {
+    pub fn new(watch_dir: &PathBuf) -> Result<Self, String> {
+        let (tx, rx) = mpsc::channel();
+
+        let mut watcher = RecommendedWatcher::new(
+            move |result: Result<Event, notify::Error>| {
+                if let Ok(event) = result {
+                    let kind = match event.kind {
+                        EventKind::Create(_) => Some(ChangeKind::Created),
+                        EventKind::Modify(_) => Some(ChangeKind::Modified),
+                        EventKind::Remove(_) => Some(ChangeKind::Deleted),
+                        _ => None,
+                    };
+                    if let Some(kind) = kind {
+                        for path in event.paths {
+                            // Skip hidden files and temp files
+                            let name = path.file_name()
+                                .and_then(|n| n.to_str())
+                                .unwrap_or("");
+                            if name.starts_with('.') || name.starts_with('~') || name.ends_with(".tmp") {
+                                continue;
+                            }
+                            let _ = tx.send(FileChange { path, kind: kind.clone() });
+                        }
+                    }
+                }
+            },
+            Config::default(),
+        ).map_err(|e| format!("Watcher-Fehler: {}", e))?;
+
+        watcher.watch(watch_dir.as_ref(), RecursiveMode::Recursive)
+            .map_err(|e| format!("Watch-Fehler: {}", e))?;
+
+        Ok(Self { _watcher: watcher, receiver: rx, path: watch_dir.clone() })
+    }
+}

clients/desktop/src-tauri/tauri.conf.json

@@ -0,0 +1,53 @@
+{
+  "$schema": "https://schema.tauri.app/config/2",
+  "productName": "MiniCloud Sync",
+  "version": "0.1.0",
+  "identifier": "com.minicloud.sync",
+  "build": {
+    "beforeDevCommand": "npm run dev",
+    "devUrl": "http://localhost:1420",
+    "beforeBuildCommand": "npm run build",
+    "frontendDist": "../dist"
+  },
+  "app": {
+    "windows": [
+      {
+        "title": "Mini-Cloud Sync",
+        "width": 700,
+        "height": 550,
+        "resizable": true,
+        "center": true
+      }
+    ],
+    "security": {
+      "csp": null
+    }
+  },
+  "bundle": {
+    "active": true,
+    "targets": "all",
+    "icon": [
+      "icons/32x32.png",
+      "icons/128x128.png",
+      "icons/128x128@2x.png",
+      "icons/icon.icns",
+      "icons/icon.ico"
+    ],
+    "fileAssociations": [
+      {
+        "ext": ["cloud"],
+        "mimeType": "application/x-minicloud",
+        "description": "Mini-Cloud Platzhalter"
+      }
+    ],
+    "windows": {
+      "nsis": {
+        "installerIcon": "icons/icon.ico",
+        "headerImage": null,
+        "sidebarImage": null,
+        "installMode": "both",
+        "displayLanguageSelector": false
+      }
+    }
+  }
+}

clients/desktop/src/App.vue

@@ -0,0 +1,752 @@
+<script setup>
+import { ref, onMounted, onUnmounted } from "vue";
+import { invoke } from "@tauri-apps/api/core";
+import { listen } from "@tauri-apps/api/event";
+import { open as dialogOpen } from "@tauri-apps/plugin-dialog";
+
+const screen = ref("login");
+const serverUrl = ref("https://");
+const username = ref("");
+const password = ref("");
+const loginError = ref("");
+const loginLoading = ref(false);
+
+const syncPaths = ref([]);
+const syncLog = ref([]);
+const syncing = ref(false);
+const syncStatus = ref("Nicht verbunden");
+const userInfo = ref(null);
+const fileTree = ref([]);
+const fileChanges = ref([]);
+const autoSyncActive = ref(false);
+const startMinimized = ref(false);
+
+async function saveStartMinimized() {
+  await invoke("set_start_minimized", { minimized: startMinimized.value });
+}
+
+// New sync path form
+const showAddPath = ref(false);
+const newPathLocal = ref("");
+const newPathServerFolder = ref("");
+const newPathServerId = ref(null);
+const newPathMode = ref("virtual");
+
+// Cloud-Files (Windows cfapi / Linux FUSE)
+const cloudFilesSupported = ref(false);
+const cloudFilesActive = ref(false);
+const cloudFilesBusy = ref(false);
+const cloudFilesMountPoint = ref("");
+const cloudFilesError = ref("");
+
+async function checkCloudFilesSupport() {
+  try { cloudFilesSupported.value = await invoke("cloud_files_supported"); }
+  catch { cloudFilesSupported.value = false; }
+  try {
+    const saved = await invoke("cloud_files_get_mount");
+    if (saved) cloudFilesMountPoint.value = saved;
+  } catch { /* no saved mount */ }
+}
+
+async function forceCleanupCloudFiles() {
+  if (!cloudFilesMountPoint.value) return;
+  if (!confirm(`Sync-Root unter ${cloudFilesMountPoint.value} zwangsweise aufraeumen?\n\nDanach kann der Ordner ggf. geloescht werden.`)) return;
+  cloudFilesError.value = "";
+  cloudFilesBusy.value = true;
+  try {
+    await invoke("cloud_files_force_cleanup", { mountPoint: cloudFilesMountPoint.value });
+    cloudFilesActive.value = false;
+    cloudFilesMountPoint.value = "";
+    syncLog.value = [`[${ts()}] Cloud-Files Zwangsbereinigung durchgefuehrt`, ...syncLog.value].slice(0, 200);
+  } catch (err) {
+    cloudFilesError.value = String(err);
+  } finally {
+    cloudFilesBusy.value = false;
+  }
+}
+
+async function browseCfMount() {
+  try {
+    const selected = await dialogOpen({ directory: true, multiple: false,
+                                        title: "Cloud-Files-Ordner waehlen" });
+    if (selected) cloudFilesMountPoint.value = selected;
+  } catch { /* cancelled */ }
+}
+
+async function enableCloudFiles() {
+  cloudFilesError.value = "";
+  cloudFilesBusy.value = true;
+  try {
+    await invoke("cloud_files_enable", { mountPoint: cloudFilesMountPoint.value });
+    cloudFilesActive.value = true;
+    syncLog.value = [`[${ts()}] Cloud-Files aktiviert: ${cloudFilesMountPoint.value}`, ...syncLog.value].slice(0, 200);
+  } catch (err) {
+    cloudFilesError.value = String(err);
+  } finally {
+    cloudFilesBusy.value = false;
+  }
+}
+
+async function disableCloudFiles() {
+  cloudFilesError.value = "";
+  cloudFilesBusy.value = true;
+  try {
+    await invoke("cloud_files_disable", { mountPoint: cloudFilesMountPoint.value });
+    cloudFilesActive.value = false;
+    syncLog.value = [`[${ts()}] Cloud-Files deaktiviert`, ...syncLog.value].slice(0, 200);
+  } catch (err) {
+    cloudFilesError.value = String(err);
+  } finally {
+    cloudFilesBusy.value = false;
+  }
+}
+const serverFolders = ref([]);
+
+// Local file browser
+const localFiles = ref([]);
+const localBreadcrumb = ref([]);
+const contextMenu = ref({ show: false, x: 0, y: 0, file: null });
+
+async function loadLocalFiles(subPath = null) {
+  try {
+    localFiles.value = await invoke("browse_sync_folder", { subPath });
+    if (subPath) {
+      // Build breadcrumb
+      const sp = syncPaths.value[0];
+      if (sp) {
+        const rel = subPath.replace(sp.local_dir, "").replace(/^[/\\]/, "");
+        const parts = rel.split(/[/\\]/).filter(Boolean);
+        localBreadcrumb.value = [{ name: "Sync", path: sp.local_dir }];
+        let current = sp.local_dir;
+        for (const p of parts) {
+          current += (current.endsWith("/") || current.endsWith("\\") ? "" : "/") + p;
+          localBreadcrumb.value.push({ name: p, path: current });
+        }
+      }
+    } else {
+      localBreadcrumb.value = [];
+    }
+  } catch { localFiles.value = []; }
+}
+
+function openLocalFolder(file) {
+  if (file.is_folder) loadLocalFiles(file.path);
+}
+
+function showContextMenu(e, file) {
+  e.preventDefault();
+  contextMenu.value = { show: true, x: e.clientX, y: e.clientY, file };
+}
+
+function hideContextMenu() {
+  contextMenu.value = { show: false, x: 0, y: 0, file: null };
+}
+
+async function doMarkOffline(file) {
+  hideContextMenu();
+  try {
+    const result = await invoke("mark_offline", { cloudPath: file.path });
+    syncLog.value = [`[${ts()}] ${result}`, ...syncLog.value].slice(0, 200);
+    await loadLocalFiles(null);
+  } catch (err) {
+    syncLog.value = [`[${ts()}] Fehler: ${err}`, ...syncLog.value].slice(0, 200);
+  }
+}
+
+async function doUnlockFile(file) {
+  hideContextMenu();
+  const fileId = file.file_id ?? findFileInTree(fileTree.value, file.name)?.id;
+  if (!fileId) {
+    syncLog.value = [`[${ts()}] Fehler: Datei nicht auf Server gefunden`, ...syncLog.value];
+    return;
+  }
+  try {
+    await invoke("unlock_file_cmd", { fileId });
+    syncLog.value = [`[${ts()}] Entsperrt: ${file.name}`, ...syncLog.value].slice(0, 200);
+  } catch (err) {
+    syncLog.value = [`[${ts()}] Fehler: ${err}`, ...syncLog.value].slice(0, 200);
+  }
+}
+
+async function doLockOnly(file) {
+  hideContextMenu();
+  const fileId = file.file_id ?? findFileInTree(fileTree.value, file.name)?.id;
+  if (!fileId) {
+    syncLog.value = [`[${ts()}] Fehler: Datei nicht auf Server gefunden`, ...syncLog.value];
+    return;
+  }
+  try {
+    await invoke("lock_file_cmd", { fileId });
+    syncLog.value = [`[${ts()}] Ausgecheckt: ${file.name}`, ...syncLog.value].slice(0, 200);
+  } catch (err) {
+    syncLog.value = [`[${ts()}] Fehler: ${err}`, ...syncLog.value].slice(0, 200);
+  }
+}
+
+function findFileInTree(entries, name) {
+  for (const e of entries) {
+    if (e.name === name) return e;
+    if (e.children) {
+      const found = findFileInTree(e.children, name);
+      if (found) return found;
+    }
+  }
+  return null;
+}
+
+async function doUnmarkOffline(file) {
+  hideContextMenu();
+  try {
+    const result = await invoke("unmark_offline", { cloudPath: file.path });
+    syncLog.value = [`[${ts()}] ${result}`, ...syncLog.value].slice(0, 200);
+    await loadLocalFiles(null);
+  } catch (err) {
+    syncLog.value = [`[${ts()}] Fehler: ${err}`, ...syncLog.value].slice(0, 200);
+  }
+}
+
+async function doOpenCloudFile(file) {
+  hideContextMenu();
+  try {
+    const realPath = await invoke("open_cloud_file", { cloudPath: file.path });
+    syncLog.value = [`[${ts()}] Geoeffnet: ${realPath}`, ...syncLog.value].slice(0, 200);
+  } catch (err) {
+    syncLog.value = [`[${ts()}] Fehler: ${err}`, ...syncLog.value].slice(0, 200);
+  }
+}
+
+async function doOpenOfflineFile(file) {
+  hideContextMenu();
+  try {
+    await invoke("open_offline_file", { realPath: file.path });
+    syncLog.value = [`[${ts()}] Ausgecheckt + geoeffnet: ${file.name}`, ...syncLog.value].slice(0, 200);
+  } catch (err) {
+    syncLog.value = [`[${ts()}] Fehler: ${err}`, ...syncLog.value].slice(0, 200);
+  }
+}
+
+let unlistenStatus, unlistenLog, unlistenError, unlistenFileChange, unlistenTrigger, unlistenCloudOpen;
+
+async function handleLogin() {
+  loginError.value = "";
+  loginLoading.value = true;
+  try {
+    const result = await invoke("login", {
+      serverUrl: serverUrl.value,
+      username: username.value,
+      password: password.value,
+    });
+    userInfo.value = result;
+    screen.value = "main";
+    syncStatus.value = `Verbunden als ${result.username}`;
+    startMinimized.value = await invoke("get_start_minimized");
+    await loadFileTree();
+    await loadSyncPaths();
+  } catch (err) {
+    loginError.value = String(err);
+  } finally {
+    loginLoading.value = false;
+  }
+}
+
+async function loadFileTree() {
+  try {
+    fileTree.value = await invoke("get_file_tree");
+    // Build flat folder list for sync path selection
+    serverFolders.value = [{ id: null, name: "/ (Alle Dateien)", path: "/" }];
+    flattenFolders(fileTree.value, "", serverFolders.value);
+  } catch (err) { console.error(err); }
+}
+
+function flattenFolders(entries, prefix, list) {
+  for (const e of entries) {
+    if (e.is_folder) {
+      const path = `${prefix}/${e.name}`;
+      list.push({ id: e.id, name: path, path });
+      if (e.children) flattenFolders(e.children, path, list);
+    }
+  }
+}
+
+async function loadSyncPaths() {
+  try { syncPaths.value = await invoke("get_sync_paths"); }
+  catch { syncPaths.value = []; }
+}
+
+async function browseFolder() {
+  try {
+    const selected = await dialogOpen({ directory: true, multiple: false, title: "Sync-Ordner waehlen" });
+    if (selected) newPathLocal.value = selected;
+  } catch { /* dialog cancelled */ }
+}
+
+async function addSyncPath() {
+  if (!newPathLocal.value) return;
+  try {
+    await invoke("add_sync_path", {
+      serverPath: newPathServerFolder.value || "/",
+      serverFolderId: newPathServerId.value,
+      localDir: newPathLocal.value,
+      mode: newPathMode.value,
+    });
+    showAddPath.value = false;
+    newPathLocal.value = "";
+    newPathServerFolder.value = "";
+    newPathServerId.value = null;
+    newPathMode.value = "virtual";
+    await loadSyncPaths();
+    // Auto-start sync now that we have a path (if not already running)
+    if (!autoSyncActive.value && syncPaths.value.length > 0) {
+      await startSync();
+    }
+  } catch (err) { alert(err); }
+}
+
+async function removeSyncPath(id) {
+  await invoke("remove_sync_path", { id });
+  await loadSyncPaths();
+  // If no paths remain, stop auto-sync
+  if (syncPaths.value.length === 0) {
+    autoSyncActive.value = false;
+    syncStatus.value = "Keine Sync-Pfade konfiguriert";
+  }
+}
+
+async function toggleMode(id) {
+  await invoke("toggle_sync_mode", { id });
+  await loadSyncPaths();
+}
+
+function selectServerFolder(folder) {
+  newPathServerFolder.value = folder.path;
+  newPathServerId.value = folder.id;
+}
+
+async function startSync() {
+  syncing.value = true;
+  syncStatus.value = "Erster Sync...";
+  try {
+    const log = await invoke("start_sync");
+    syncLog.value = [...log.map(m => `[${ts()}] ${m}`), ...syncLog.value].slice(0, 200);
+    syncStatus.value = "Synchronisiert";
+    autoSyncActive.value = true;
+    await loadFileTree();
+    await loadLocalFiles(null);
+  } catch (err) { syncStatus.value = `Fehler: ${err}`; }
+  finally { syncing.value = false; }
+}
+
+async function syncNow() {
+  syncing.value = true;
+  try {
+    const log = await invoke("run_sync_now");
+    syncLog.value = [...log.map(m => `[${ts()}] ${m}`), ...syncLog.value].slice(0, 200);
+    await loadFileTree();
+  } catch (err) { syncStatus.value = `Fehler: ${err}`; }
+  finally { syncing.value = false; }
+}
+
+function ts() {
+  return new Date().toLocaleTimeString("de-DE", { hour: "2-digit", minute: "2-digit", second: "2-digit" });
+}
+
+function formatSize(b) {
+  if (!b) return "";
+  const u = ["B","KB","MB","GB"]; let i=0; let s=b;
+  while (s>=1024 && i<u.length-1) { s/=1024; i++; }
+  return `${s.toFixed(i>0?1:0)} ${u[i]}`;
+}
+
+onMounted(async () => {
+  await checkCloudFilesSupport();
+  // Try auto-login with saved credentials
+  try {
+    const saved = await invoke("load_saved_config");
+    if (saved.has_credentials) {
+      loginLoading.value = true;
+      serverUrl.value = saved.server_url;
+      username.value = saved.username;
+      try {
+        const result = await invoke("auto_login");
+        userInfo.value = result;
+        screen.value = "main";
+        syncStatus.value = `Verbunden als ${result.username}`;
+        syncPaths.value = (await invoke("get_sync_paths"));
+        startMinimized.value = await invoke("get_start_minimized");
+        await loadFileTree();
+        // Auto-start sync if paths configured
+        if (syncPaths.value.length > 0) {
+          await startSync();
+        }
+        // Cloud-Files automatisch reaktivieren, wenn Mount gespeichert.
+        if (cloudFilesSupported.value && cloudFilesMountPoint.value) {
+          try {
+            await invoke("cloud_files_enable", { mountPoint: cloudFilesMountPoint.value });
+            cloudFilesActive.value = true;
+          } catch (e) {
+            cloudFilesError.value = `Auto-Reaktivierung fehlgeschlagen: ${e}`;
+          }
+        }
+      } catch (err) {
+        syncStatus.value = "Auto-Login fehlgeschlagen";
+        // Show login screen with pre-filled fields
+      }
+      loginLoading.value = false;
+    } else if (saved.has_config) {
+      serverUrl.value = saved.server_url;
+      username.value = saved.username;
+    }
+  } catch { /* no saved config */ }
+
+  unlistenStatus = await listen("sync-status", e => {
+    syncing.value = e.payload === "syncing";
+    syncStatus.value = e.payload === "syncing" ? "Synchronisiere..." : "Synchronisiert";
+    if (e.payload === "synced") { loadFileTree(); loadLocalFiles(null); }
+  });
+  unlistenLog = await listen("sync-log", e => {
+    syncLog.value = [...e.payload.map(m => `[${ts()}] ${m}`), ...syncLog.value].slice(0, 200);
+  });
+  unlistenError = await listen("sync-error", e => {
+    syncStatus.value = `Fehler: ${e.payload}`;
+    syncing.value = false;
+  });
+  unlistenFileChange = await listen("file-change", e => {
+    fileChanges.value = [`[${ts()}] ${e.payload}`, ...fileChanges.value].slice(0, 50);
+  });
+  unlistenTrigger = await listen("trigger-sync", () => syncNow());
+  // Server-Push: bei jedem File-Event Server-Tree + Lokale Liste neu laden,
+  // damit Lock-Status, neue/geloeschte Dateien sofort angezeigt werden.
+  await listen("sse-event", () => {
+    loadFileTree();
+    loadLocalFiles(null);
+  });
+  unlistenCloudOpen = await listen("open-cloud-file", async (e) => {
+    const cloudPath = e.payload;
+    syncLog.value = [`[${ts()}] Oeffne: ${cloudPath}`, ...syncLog.value].slice(0, 200);
+    try {
+      const realPath = await invoke("open_cloud_file", { cloudPath });
+      syncLog.value = [`[${ts()}] Geoeffnet: ${realPath}`, ...syncLog.value].slice(0, 200);
+    } catch (err) {
+      syncLog.value = [`[${ts()}] Fehler: ${err}`, ...syncLog.value].slice(0, 200);
+    }
+  });
+});
+onUnmounted(() => { unlistenStatus?.(); unlistenLog?.(); unlistenError?.(); unlistenFileChange?.(); unlistenTrigger?.(); unlistenCloudOpen?.(); });
+</script>
+
+<template>
+  <!-- Login -->
+  <div v-if="screen === 'login'" class="login-screen">
+    <div class="login-card">
+      <div class="login-header">
+        <div class="logo-icon">☁</div>
+        <h1>Mini-Cloud</h1>
+        <p>Desktop Sync Client</p>
+      </div>
+      <form @submit.prevent="handleLogin">
+        <div class="field"><label>Server-URL</label><input v-model="serverUrl" placeholder="https://cloud.example.com" /></div>
+        <div class="field"><label>Benutzername</label><input v-model="username" autofocus /></div>
+        <div class="field"><label>Passwort</label><input v-model="password" type="password" /></div>
+        <div v-if="loginError" class="error">{{ loginError }}</div>
+        <button type="submit" :disabled="loginLoading" class="btn-primary full">{{ loginLoading ? "Verbinde..." : "Anmelden" }}</button>
+      </form>
+    </div>
+  </div>
+
+  <!-- Main -->
+  <div v-else class="main-screen">
+    <div class="toolbar">
+      <div class="toolbar-left">
+        <span class="logo-small">☁</span><strong>Mini-Cloud Sync</strong>
+        <span class="status-badge" :class="{ syncing, error: syncStatus.startsWith('Fehler') }">
+          <span v-if="syncing" class="spin">⟳</span> {{ syncStatus }}
+        </span>
+      </div>
+      <div class="toolbar-right"><span class="user-info">{{ userInfo?.username }}</span></div>
+    </div>
+
+    <div class="content">
+      <!-- Cloud-Files (Windows Cloud Files API, OneDrive-artig) -->
+      <div class="section">
+        <div class="section-header">
+          <h3>Cloud-Files (OneDrive-Style)</h3>
+          <span v-if="cloudFilesActive" class="status-badge syncing">☁ aktiv</span>
+          <span v-else-if="!cloudFilesSupported" class="status-badge error">nicht verfuegbar</span>
+        </div>
+        <p class="hint">
+          Dateien erscheinen als Platzhalter im Explorer mit Wolken-Icon und
+          werden erst bei Zugriff geladen. Rechtsklick im Explorer &rarr;
+          "Immer offline halten" oder "Speicher freigeben".
+        </p>
+        <p v-if="!cloudFilesSupported" class="hint" style="color:#c62828">
+          Auf dieser Plattform noch nicht verfuegbar. Aktuell: Windows 10/11.
+          Linux-FUSE ist in Vorbereitung, macOS folgt mit Apple-Signatur.
+        </p>
+        <template v-else>
+          <div class="cf-row">
+            <input v-model="cloudFilesMountPoint" placeholder="Ordner waehlen..." />
+            <button class="btn-secondary" @click="browseCfMount">Durchsuchen</button>
+            <button v-if="!cloudFilesActive" class="btn-primary"
+                    :disabled="!cloudFilesMountPoint || cloudFilesBusy"
+                    @click="enableCloudFiles">
+              {{ cloudFilesBusy ? "Aktiviere..." : "Aktivieren" }}
+            </button>
+            <button v-else class="btn-secondary" :disabled="cloudFilesBusy"
+                    @click="disableCloudFiles">Deaktivieren</button>
+            <button v-if="cloudFilesMountPoint && !cloudFilesActive"
+                    class="btn-secondary" :disabled="cloudFilesBusy"
+                    @click="forceCleanupCloudFiles"
+                    title="Toten Sync-Root nach hartem Beenden des Clients aufraeumen">
+              Aufraeumen
+            </button>
+          </div>
+          <div v-if="cloudFilesError" class="error" style="margin-top:0.5rem">{{ cloudFilesError }}</div>
+        </template>
+      </div>
+
+      <!-- Sync Paths (Legacy) - auf Windows ausgeblendet sobald Cloud-Files
+           aktiv ist; Cloud-Files ersetzt diese Ansicht vollstaendig. -->
+      <div v-if="!cloudFilesActive" class="section">
+        <div class="section-header">
+          <h3>Sync-Pfade</h3>
+          <div class="header-btns">
+            <button v-if="syncPaths.length && !autoSyncActive" @click="startSync" :disabled="syncing" class="btn-primary">Sync starten</button>
+            <button v-if="autoSyncActive" @click="syncNow" :disabled="syncing" class="btn-small">Jetzt synchronisieren</button>
+            <button @click="showAddPath = !showAddPath" class="btn-small">+ Pfad hinzufuegen</button>
+          </div>
+        </div>
+
+        <div v-if="autoSyncActive" class="auto-info">Auto-Sync alle 30s aktiv</div>
+
+        <!-- Add new sync path -->
+        <div v-if="showAddPath" class="add-path-form">
+          <div class="field">
+            <label>Server-Ordner</label>
+            <select v-model="newPathServerId" @change="selectServerFolder(serverFolders.find(f => f.id === newPathServerId))">
+              <option v-for="f in serverFolders" :key="f.id ?? 'root'" :value="f.id">{{ f.name }}</option>
+            </select>
+          </div>
+          <div class="field">
+            <label>Lokaler Ordner</label>
+            <div class="browse-row">
+              <input v-model="newPathLocal" placeholder="/home/user/MiniCloud" />
+              <button @click="browseFolder" class="btn-small">Durchsuchen...</button>
+            </div>
+          </div>
+          <div class="field">
+            <label>Modus</label>
+            <div class="mode-select">
+              <label class="mode-option" :class="{ active: newPathMode === 'virtual' }">
+                <input type="radio" v-model="newPathMode" value="virtual" /> ☁ Virtual Files
+                <small>Platzhalter, Download bei Bedarf</small>
+              </label>
+              <label class="mode-option" :class="{ active: newPathMode === 'full' }">
+                <input type="radio" v-model="newPathMode" value="full" /> 💾 Full Sync
+                <small>Alle Dateien lokal spiegeln</small>
+              </label>
+            </div>
+          </div>
+          <div class="form-actions">
+            <button @click="showAddPath = false" class="btn-small">Abbrechen</button>
+            <button @click="addSyncPath" class="btn-primary" :disabled="!newPathLocal">Hinzufuegen</button>
+          </div>
+        </div>
+
+        <!-- Existing sync paths -->
+        <div v-for="sp in syncPaths" :key="sp.id" class="sync-path-card">
+          <div class="sp-info">
+            <div class="sp-server">☁ {{ sp.server_path }}</div>
+            <div class="sp-arrow">→</div>
+            <div class="sp-local">📁 {{ sp.local_dir }}</div>
+          </div>
+          <div class="sp-actions">
+            <span class="sp-mode" :class="sp.mode" @click="toggleMode(sp.id)" :title="'Klicken zum Wechseln'">
+              {{ sp.mode === 'Full' ? '💾 Full' : '☁ Virtual' }}
+            </span>
+            <button @click="removeSyncPath(sp.id)" class="btn-danger" title="Entfernen">✕</button>
+          </div>
+        </div>
+
+        <div v-if="!syncPaths.length && !showAddPath" class="empty">
+          Noch keine Sync-Pfade. Klicke "Pfad hinzufuegen" um loszulegen.
+        </div>
+      </div>
+
+      <!-- Local File Browser (Legacy, nur fuer Full-Sync-Modus) -->
+      <div v-if="autoSyncActive && !cloudFilesActive" class="section" @click="hideContextMenu">
+        <div class="section-header">
+          <h3>Lokale Dateien</h3>
+          <button @click="loadLocalFiles(null)" class="btn-small">↻</button>
+        </div>
+
+        <div v-if="localBreadcrumb.length" class="local-breadcrumb">
+          <span v-for="(b, i) in localBreadcrumb" :key="i">
+            <a @click="loadLocalFiles(b.path)">{{ b.name }}</a>
+            <span v-if="i < localBreadcrumb.length - 1"> / </span>
+          </span>
+        </div>
+
+        <div class="local-file-list">
+          <div v-for="f in localFiles" :key="f.path"
+               class="local-file-item"
+               @dblclick="f.is_folder ? openLocalFolder(f) : (f.is_cloud ? doOpenCloudFile(f) : doOpenOfflineFile(f))"
+               @contextmenu="showContextMenu($event, f)">
+            <span class="lf-icon">{{ f.is_folder ? '📁' : (f.is_cloud ? '☁' : '📄') }}</span>
+            <span class="lf-name">{{ f.name }}</span>
+            <span v-if="f.is_cloud" class="lf-badge cloud">Cloud</span>
+            <span v-else-if="f.is_offline" class="lf-badge offline">Offline</span>
+            <span v-if="f.locked" class="lf-badge locked" :title="'Ausgecheckt von ' + f.locked_by">🔒 {{ f.locked_by }}</span>
+            <span class="lf-size">{{ formatSize(f.cloud_size || f.size) }}</span>
+          </div>
+          <div v-if="!localFiles.length" class="empty">Ordner ist leer</div>
+        </div>
+      </div>
+
+      <!-- Context Menu -->
+      <div v-if="contextMenu.show" class="context-menu"
+           :style="{ left: contextMenu.x + 'px', top: contextMenu.y + 'px' }">
+        <div v-if="contextMenu.file?.is_cloud" class="cm-item" @click="doOpenCloudFile(contextMenu.file)">
+          📥 Oeffnen (herunterladen)
+        </div>
+        <div v-if="contextMenu.file?.is_cloud" class="cm-item" @click="doMarkOffline(contextMenu.file)">
+          💾 Offline verfuegbar machen
+        </div>
+        <div v-if="contextMenu.file?.is_offline" class="cm-item" @click="doOpenOfflineFile(contextMenu.file)">
+          📂 Oeffnen (auschecken)
+        </div>
+        <div v-if="contextMenu.file?.is_offline && !contextMenu.file?.locked" class="cm-item" @click="doLockOnly(contextMenu.file)">
+          🔒 Auschecken (sperren)
+        </div>
+        <div v-if="contextMenu.file?.is_offline && contextMenu.file?.locked" class="cm-item" @click="doUnlockFile(contextMenu.file)">
+          🔓 Entsperren (einchecken)
+        </div>
+        <div v-if="contextMenu.file?.is_offline" class="cm-item" @click="doUnmarkOffline(contextMenu.file)">
+          ☁ Nicht mehr offline (Platzhalter)
+        </div>
+        <div class="cm-item" @click="hideContextMenu">Abbrechen</div>
+      </div>
+
+      <!-- File Tree -->
+      <div class="section">
+        <div class="section-header">
+          <h3>Server-Dateien</h3>
+          <button @click="loadFileTree" class="btn-small">↻</button>
+        </div>
+        <div class="file-tree">
+          <template v-for="e in fileTree" :key="e.id">
+            <div class="tree-item">
+              <span class="tree-icon">{{ e.is_folder ? '📁' : '📄' }}</span>
+              <span class="tree-name">{{ e.name }}</span>
+              <span v-if="e.locked" class="tree-lock">🔒 {{ e.locked_by }}</span>
+              <span v-if="!e.is_folder" class="tree-size">{{ formatSize(e.size) }}</span>
+            </div>
+            <div v-if="e.children" v-for="c in e.children" :key="c.id" class="tree-item indent">
+              <span class="tree-icon">{{ c.is_folder ? '📁' : '📄' }}</span>
+              <span class="tree-name">{{ c.name }}</span>
+              <span v-if="c.locked" class="tree-lock">🔒 {{ c.locked_by }}</span>
+              <span v-if="!c.is_folder" class="tree-size">{{ formatSize(c.size) }}</span>
+            </div>
+          </template>
+          <div v-if="!fileTree.length" class="empty">Keine Dateien</div>
+        </div>
+      </div>
+
+      <!-- File Changes -->
+      <div v-if="fileChanges.length" class="section">
+        <h3>Lokale Aenderungen</h3>
+        <div class="log-list"><div v-for="(m,i) in fileChanges" :key="i" class="log-item change">{{ m }}</div></div>
+      </div>
+
+      <!-- Sync Log -->
+      <div v-if="syncLog.length" class="section">
+        <h3>Sync-Protokoll</h3>
+        <div class="log-list"><div v-for="(m,i) in syncLog" :key="i" class="log-item">{{ m }}</div></div>
+      </div>
+
+      <!-- Settings -->
+      <div class="section">
+        <h3>Einstellungen</h3>
+        <label class="checkbox-row">
+          <input type="checkbox" v-model="startMinimized" @change="saveStartMinimized" />
+          Minimiert starten (direkt im System-Tray)
+        </label>
+      </div>
+    </div>
+  </div>
+</template>
+
+<style>
+*{box-sizing:border-box;margin:0;padding:0}
+body{font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;font-size:14px;color:#1a1a1a;background:#f0f2f5}
+.login-screen{height:100vh;display:flex;align-items:center;justify-content:center}
+.login-card{background:#fff;border-radius:12px;padding:2rem;width:360px;box-shadow:0 2px 12px rgba(0,0,0,.1)}
+.login-header{text-align:center;margin-bottom:1.5rem}
+.logo-icon{font-size:2.5rem}.login-header h1{font-size:1.3rem;margin:.5rem 0 .25rem}.login-header p{color:#666;font-size:.85rem}
+.field{margin-bottom:.75rem}.field label{display:block;margin-bottom:.25rem;font-weight:500;font-size:.85rem}
+.field input,.field select{width:100%;padding:.5rem;border:1px solid #ddd;border-radius:6px;font-size:.9rem;background:#fafafa}
+.field input:focus,.field select:focus{border-color:#4a90d9;outline:none;background:#fff}
+.error{color:#e53e3e;font-size:.85rem;margin-bottom:.75rem}
+.btn-primary{padding:.5rem 1rem;background:#4a90d9;color:#fff;border:none;border-radius:6px;font-size:.85rem;cursor:pointer;font-weight:500;white-space:nowrap}
+.btn-primary:hover{background:#3a7bc8}.btn-primary:disabled{opacity:.6;cursor:not-allowed}
+.btn-primary.full{width:100%}
+.btn-small{padding:.25rem .5rem;background:#e8e8e8;border:none;border-radius:4px;font-size:.8rem;cursor:pointer}
+.btn-small:hover{background:#ddd}
+.btn-danger{padding:.25rem .5rem;background:#fee;color:#c00;border:none;border-radius:4px;font-size:.8rem;cursor:pointer}
+.btn-danger:hover{background:#fcc}
+.main-screen{height:100vh;display:flex;flex-direction:column}
+.toolbar{display:flex;align-items:center;justify-content:space-between;padding:.5rem 1rem;background:#fff;border-bottom:1px solid #e0e0e0}
+.toolbar-left{display:flex;align-items:center;gap:.5rem}.logo-small{font-size:1.2rem}
+.status-badge{font-size:.8rem;padding:.2rem .5rem;border-radius:4px;background:#e8f5e9;color:#2e7d32}
+.status-badge.syncing{background:#fff3e0;color:#e65100}.status-badge.error{background:#ffebee;color:#c62828}
+.spin{display:inline-block;animation:spin 1s linear infinite}@keyframes spin{from{transform:rotate(0)}to{transform:rotate(360deg)}}
+.user-info{font-size:.85rem;color:#666}
+.content{flex:1;overflow-y:auto;padding:1rem}
+.section{background:#fff;border-radius:8px;padding:1rem;margin-bottom:.75rem}
+.section h3{margin-bottom:.5rem;font-size:.95rem}
+.section-header{display:flex;align-items:center;justify-content:space-between;margin-bottom:.5rem}
+.section-header h3{margin:0}.header-btns{display:flex;gap:.5rem}
+.auto-info{font-size:.8rem;color:#2e7d32;margin-bottom:.5rem}
+.add-path-form{border:1px solid #e0e0e0;border-radius:8px;padding:1rem;margin-bottom:.75rem;background:#fafafa}
+.browse-row{display:flex;gap:.5rem}
+.browse-row input{flex:1}
+.mode-select{display:flex;gap:.5rem}
+.mode-option{flex:1;display:flex;flex-direction:column;padding:.5rem;border:2px solid #e0e0e0;border-radius:6px;cursor:pointer;font-size:.85rem}
+.mode-option.active{border-color:#4a90d9;background:#f0f7ff}
+.mode-option input{margin-right:.25rem}
+.mode-option small{color:#888;font-size:.75rem;margin-top:.25rem}
+.form-actions{display:flex;justify-content:flex-end;gap:.5rem;margin-top:.75rem}
+.sync-path-card{display:flex;align-items:center;justify-content:space-between;padding:.5rem .75rem;border:1px solid #e8e8e8;border-radius:6px;margin-bottom:.375rem;font-size:.85rem}
+.sp-info{display:flex;align-items:center;gap:.375rem;flex:1;min-width:0}
+.sp-server,.sp-local{overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
+.sp-server{color:#4a90d9}.sp-arrow{color:#999;flex-shrink:0}.sp-local{color:#555}
+.sp-actions{display:flex;align-items:center;gap:.375rem;flex-shrink:0}
+.sp-mode{font-size:.75rem;padding:.2rem .4rem;border-radius:4px;cursor:pointer;background:#f0f0f0}
+.sp-mode.Full{background:#e3f2fd;color:#1565c0}.sp-mode.Virtual{background:#f3e5f5;color:#7b1fa2}
+.cf-row{display:flex;gap:.5rem;align-items:center;flex-wrap:wrap}
+.cf-row input{flex:1;min-width:300px}
+.file-tree{max-height:250px;overflow-y:auto}
+.tree-item{display:flex;align-items:center;gap:.5rem;padding:.3rem 0;border-bottom:1px solid #f5f5f5;font-size:.85rem}
+.tree-item.indent{padding-left:1.5rem}.tree-icon{flex-shrink:0}.tree-name{flex:1;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
+.tree-lock{font-size:.75rem;color:#e67e22;flex-shrink:0}.tree-size{font-size:.75rem;color:#999;flex-shrink:0}
+.empty{text-align:center;color:#999;padding:1rem;font-size:.85rem}
+.log-list{max-height:150px;overflow-y:auto;font-family:monospace;font-size:.78rem}
+.log-item{padding:.2rem 0;border-bottom:1px solid #f8f8f8;color:#555}.log-item.change{color:#1565c0}
+.local-breadcrumb{font-size:.85rem;margin-bottom:.5rem;color:#666}
+.local-breadcrumb a{color:#4a90d9;cursor:pointer;text-decoration:none}
+.local-breadcrumb a:hover{text-decoration:underline}
+.local-file-list{max-height:300px;overflow-y:auto}
+.local-file-item{display:flex;align-items:center;gap:.5rem;padding:.35rem .25rem;border-bottom:1px solid #f5f5f5;font-size:.85rem;cursor:default;user-select:none}
+.local-file-item:hover{background:#f8f8f8}
+.lf-icon{flex-shrink:0;font-size:1rem}
+.lf-name{flex:1;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
+.lf-badge{font-size:.65rem;padding:.1rem .3rem;border-radius:3px;flex-shrink:0}
+.lf-badge.cloud{background:#e3f2fd;color:#1565c0}
+.lf-badge.offline{background:#e8f5e9;color:#2e7d32}
+.lf-badge.locked{background:#fff3e0;color:#e65100}
+.lf-size{font-size:.75rem;color:#999;flex-shrink:0}
+.checkbox-row{display:flex;align-items:center;gap:.5rem;font-size:.85rem;cursor:pointer}
+.context-menu{position:fixed;background:#fff;border:1px solid #ddd;border-radius:6px;box-shadow:0 4px 12px rgba(0,0,0,.15);z-index:9999;min-width:200px;padding:.25rem 0}
+.cm-item{padding:.5rem .75rem;cursor:pointer;font-size:.85rem}
+.cm-item:hover{background:#f0f0f0}
+@media(prefers-color-scheme:dark){body{color:#e0e0e0;background:#1a1a1a}.login-card,.section{background:#2a2a2a}.toolbar{background:#2a2a2a;border-color:#3a3a3a}.field input,.field select{background:#333;border-color:#444;color:#e0e0e0}.status-badge{background:#1b5e20;color:#a5d6a7}.status-badge.syncing{background:#e65100;color:#ffcc80}.add-path-form{background:#333;border-color:#444}.mode-option{border-color:#444}.mode-option.active{border-color:#4a90d9;background:#1a3a5c}.sync-path-card{border-color:#3a3a3a}.tree-item{border-color:#333}.log-item{border-color:#333;color:#aaa}.log-item.change{color:#64b5f6}.local-file-item{border-color:#333}.local-file-item:hover{background:#333}.context-menu{background:#2a2a2a;border-color:#444}.cm-item:hover{background:#3a3a3a}}
+</style>

clients/desktop/src/assets/vue.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" aria-hidden="true" role="img" class="iconify iconify--logos" width="37.07" height="36" preserveAspectRatio="xMidYMid meet" viewBox="0 0 256 198"><path fill="#41B883" d="M204.8 0H256L128 220.8L0 0h97.92L128 51.2L157.44 0h47.36Z"></path><path fill="#41B883" d="m0 0l128 220.8L256 0h-51.2L128 132.48L50.56 0H0Z"></path><path fill="#35495E" d="M50.56 0L128 133.12L204.8 0h-47.36L128 51.2L97.92 0H50.56Z"></path></svg>

clients/desktop/src/main.js

@@ -0,0 +1,4 @@
+import { createApp } from "vue";
+import App from "./App.vue";
+
+createApp(App).mount("#app");

clients/desktop/vite.config.js

@@ -0,0 +1,31 @@
+import { defineConfig } from "vite";
+import vue from "@vitejs/plugin-vue";
+
+const host = process.env.TAURI_DEV_HOST;
+
+// https://vite.dev/config/
+export default defineConfig(async () => ({
+  plugins: [vue()],
+
+  // Vite options tailored for Tauri development and only applied in `tauri dev` or `tauri build`
+  //
+  // 1. prevent Vite from obscuring rust errors
+  clearScreen: false,
+  // 2. tauri expects a fixed port, fail if that port is not available
+  server: {
+    port: 1420,
+    strictPort: true,
+    host: host || false,
+    hmr: host
+      ? {
+          protocol: "ws",
+          host,
+          port: 1421,
+        }
+      : undefined,
+    watch: {
+      // 3. tell Vite to ignore watching `src-tauri`
+      ignored: ["**/src-tauri/**"],
+    },
+  },
+}));

docker-compose.yml

@@ -21,6 +21,8 @@ services:
     environment:
       - JWT_ENABLED=true
       - JWT_SECRET=${JWT_SECRET_KEY}
+      - ALLOW_META_IP_ADDRESS=true
+      - ALLOW_PRIVATE_IP_ADDRESS=true
     volumes:
       - ./data/onlyoffice/logs:/var/log/onlyoffice
       - ./data/onlyoffice/data:/var/www/onlyoffice/Data

frontend/index.html

@@ -4,7 +4,7 @@
     <meta charset="UTF-8" />
     <link rel="icon" type="image/svg+xml" href="/favicon.svg" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
-    <title>frontend</title>
+    <title>Mini-Cloud</title>
   </head>
   <body>
     <div id="app"></div>

frontend/package-lock.json

@@ -8,11 +8,18 @@
       "name": "frontend",
       "version": "0.0.0",
       "dependencies": {
+        "@fullcalendar/core": "^6.1.15",
+        "@fullcalendar/daygrid": "^6.1.15",
+        "@fullcalendar/interaction": "^6.1.15",
+        "@fullcalendar/rrule": "^6.1.15",
+        "@fullcalendar/timegrid": "^6.1.15",
+        "@fullcalendar/vue3": "^6.1.15",
         "@primevue/themes": "^4.5.4",
         "axios": "^1.15.0",
         "pinia": "^3.0.4",
         "primeicons": "^7.0.0",
         "primevue": "^4.5.5",
+        "rrule": "^2.8.1",
         "vue": "^3.5.32",
         "vue-router": "^4.6.4"
       },
@@ -101,6 +108,65 @@
         "tslib": "^2.4.0"
       }
     },
+    "node_modules/@fullcalendar/core": {
+      "version": "6.1.20",
+      "resolved": "https://registry.npmjs.org/@fullcalendar/core/-/core-6.1.20.tgz",
+      "integrity": "sha512-1cukXLlePFiJ8YKXn/4tMKsy0etxYLCkXk8nUCFi11nRONF2Ba2CD5b21/ovtOO2tL6afTJfwmc1ed3HG7eB1g==",
+      "license": "MIT",
+      "dependencies": {
+        "preact": "~10.12.1"
+      }
+    },
+    "node_modules/@fullcalendar/daygrid": {
+      "version": "6.1.20",
+      "resolved": "https://registry.npmjs.org/@fullcalendar/daygrid/-/daygrid-6.1.20.tgz",
+      "integrity": "sha512-AO9vqhkLP77EesmJzuU+IGXgxNulsA8mgQHynclJ8U70vSwAVnbcLG9qftiTAFSlZjiY/NvhE7sflve6cJelyQ==",
+      "license": "MIT",
+      "peerDependencies": {
+        "@fullcalendar/core": "~6.1.20"
+      }
+    },
+    "node_modules/@fullcalendar/interaction": {
+      "version": "6.1.20",
+      "resolved": "https://registry.npmjs.org/@fullcalendar/interaction/-/interaction-6.1.20.tgz",
+      "integrity": "sha512-p6txmc5txL0bMiPaJxe2ip6o0T384TyoD2KGdsU6UjZ5yoBlaY+dg7kxfnYKpYMzEJLG58n+URrHr2PgNL2fyA==",
+      "license": "MIT",
+      "peerDependencies": {
+        "@fullcalendar/core": "~6.1.20"
+      }
+    },
+    "node_modules/@fullcalendar/rrule": {
+      "version": "6.1.20",
+      "resolved": "https://registry.npmjs.org/@fullcalendar/rrule/-/rrule-6.1.20.tgz",
+      "integrity": "sha512-5Awk7bmaA97hSZRpIBehenXkYreVIvx8nnaMFZ/LDGRuK1mgbR4vSUrDTvVU+oEqqKnj/rqMBByWqN5NeehQxw==",
+      "license": "MIT",
+      "peerDependencies": {
+        "@fullcalendar/core": "~6.1.20",
+        "rrule": "^2.6.0"
+      }
+    },
+    "node_modules/@fullcalendar/timegrid": {
+      "version": "6.1.20",
+      "resolved": "https://registry.npmjs.org/@fullcalendar/timegrid/-/timegrid-6.1.20.tgz",
+      "integrity": "sha512-4H+/MWbz3ntA50lrPif+7TsvMeX3R1GSYjiLULz0+zEJ7/Yfd9pupZmAwUs/PBpA6aAcFmeRr0laWfcz1a9V1A==",
+      "license": "MIT",
+      "dependencies": {
+        "@fullcalendar/daygrid": "~6.1.20"
+      },
+      "peerDependencies": {
+        "@fullcalendar/core": "~6.1.20"
+      }
+    },
+    "node_modules/@fullcalendar/vue3": {
+      "version": "6.1.20",
+      "resolved": "https://registry.npmjs.org/@fullcalendar/vue3/-/vue3-6.1.20.tgz",
+      "integrity": "sha512-8qg6pS27II9QBwFkkJC+7SfflMpWqOe7i3ii5ODq9KpLAjwQAd/zjfq8RvKR1Yryoh5UmMCmvRbMB7i4RGtqog==",
+      "license": "MIT",
+      "peerDependencies": {
+        "@fullcalendar/core": "~6.1.20",
+        "vue": "^3.0.11"
+      }
+    },
     "node_modules/@jridgewell/sourcemap-codec": {
       "version": "1.5.5",
       "resolved": "https://registry.npmjs.org/@jridgewell/sourcemap-codec/-/sourcemap-codec-1.5.5.tgz",
@@ -1393,6 +1459,16 @@
         "node": "^10 || ^12 || >=14"
       }
     },
+    "node_modules/preact": {
+      "version": "10.12.1",
+      "resolved": "https://registry.npmjs.org/preact/-/preact-10.12.1.tgz",
+      "integrity": "sha512-l8386ixSsBdbreOAkqtrwqHwdvR35ID8c3rKPa8lCWuO86dBi32QWHV4vfsZK1utLLFMvw+Z5Ad4XLkZzchscg==",
+      "license": "MIT",
+      "funding": {
+        "type": "opencollective",
+        "url": "https://opencollective.com/preact"
+      }
+    },
     "node_modules/primeicons": {
       "version": "7.0.0",
       "resolved": "https://registry.npmjs.org/primeicons/-/primeicons-7.0.0.tgz",
@@ -1471,6 +1547,15 @@
       "dev": true,
       "license": "MIT"
     },
+    "node_modules/rrule": {
+      "version": "2.8.1",
+      "resolved": "https://registry.npmjs.org/rrule/-/rrule-2.8.1.tgz",
+      "integrity": "sha512-hM3dHSBMeaJ0Ktp7W38BJZ7O1zOgaFEsn41PDk+yHoEtfLV+PoJt9E9xAlZiWgf/iqEqionN0ebHFZIDAp+iGw==",
+      "license": "BSD-3-Clause",
+      "dependencies": {
+        "tslib": "^2.4.0"
+      }
+    },
     "node_modules/source-map-js": {
       "version": "1.2.1",
       "resolved": "https://registry.npmjs.org/source-map-js/-/source-map-js-1.2.1.tgz",
@@ -1522,9 +1607,7 @@
       "version": "2.8.1",
       "resolved": "https://registry.npmjs.org/tslib/-/tslib-2.8.1.tgz",
       "integrity": "sha512-oJFu94HQb+KVduSUQL7wnpmqnfmLsOA/nAh6b6EH0wCEoK0/mPeXU6c3wKDV83MkOuHPRHtSXKKU99IBazS/2w==",
-      "dev": true,
+      "license": "0BSD"
-      "license": "0BSD",
-      "optional": true
     },
     "node_modules/vite": {
       "version": "8.0.8",

frontend/package.json

@@ -9,11 +9,18 @@
     "preview": "vite preview"
   },
   "dependencies": {
+    "@fullcalendar/core": "^6.1.15",
+    "@fullcalendar/daygrid": "^6.1.15",
+    "@fullcalendar/interaction": "^6.1.15",
+    "@fullcalendar/rrule": "^6.1.15",
+    "@fullcalendar/timegrid": "^6.1.15",
+    "@fullcalendar/vue3": "^6.1.15",
     "@primevue/themes": "^4.5.4",
     "axios": "^1.15.0",
     "pinia": "^3.0.4",
     "primeicons": "^7.0.0",
     "primevue": "^4.5.5",
+    "rrule": "^2.8.1",
     "vue": "^3.5.32",
     "vue-router": "^4.6.4"
   },

frontend/src/App.vue

@@ -1,3 +1,16 @@
 <template>
   <router-view />
 </template>
+
+<script setup>
+import { watchEffect } from 'vue'
+import { useAuthStore } from './stores/auth'
+
+const auth = useAuthStore()
+
+watchEffect(() => {
+  document.title = auth.user?.username
+    ? `Mini-Cloud - ${auth.user.username}`
+    : 'Mini-Cloud'
+})
+</script>

frontend/src/router/index.js

@@ -48,6 +48,11 @@ const routes = [
         name: 'Contacts',
         component: () => import('../views/ContactsView.vue'),
       },
+      {
+        path: 'tasks',
+        name: 'Tasks',
+        component: () => import('../views/TasksView.vue'),
+      },
       {
         path: 'email',
         name: 'Email',
@@ -71,6 +76,11 @@ const routes = [
       },
     ],
   },
+  {
+    path: '/clients',
+    name: 'Clients',
+    component: () => import('../views/ClientsView.vue'),
+  },
   {
     path: '/share/:token',
     name: 'Share',

frontend/src/stores/files.js

@@ -17,6 +17,13 @@ export const useFilesStore = defineStore('files', () => {
       const response = await apiClient.get('/files', { params })
       files.value = response.data.files
       breadcrumb.value = response.data.breadcrumb
+    } catch (err) {
+      // Let the caller handle access/deletion errors - just clear the list
+      if (err.response && (err.response.status === 403 || err.response.status === 404)) {
+        files.value = []
+        breadcrumb.value = []
+      }
+      throw err
     } finally {
       loading.value = false
     }

frontend/src/views/AdminView.vue

@@ -37,6 +37,28 @@
       </div>
     </div>
 
+    <!-- System-Info: Zeitzone & NTP (read-only) -->
+    <div class="admin-section">
+      <h3>System-Zeit</h3>
+      <p class="hint">Wird in der <code>.env</code> festgelegt (Keys <code>TZ</code> und <code>NTP_SERVER</code>).
+        Aenderungen erfordern einen Neustart des Backends.</p>
+      <div class="sysinfo">
+        <div class="sysinfo-row">
+          <span class="sysinfo-label">Zeitzone:</span>
+          <code>{{ settings.timezone || '—' }}</code>
+          <span v-if="settings.timezone_abbr" class="sysinfo-extra">({{ settings.timezone_abbr }})</span>
+        </div>
+        <div class="sysinfo-row">
+          <span class="sysinfo-label">Aktuelle Server-Zeit:</span>
+          <code>{{ formatServerTime(settings.server_time) }}</code>
+        </div>
+        <div class="sysinfo-row">
+          <span class="sysinfo-label">NTP-Server:</span>
+          <code>{{ settings.ntp_server || '(deaktiviert)' }}</code>
+        </div>
+      </div>
+    </div>
+
     <!-- System Email -->
     <div class="admin-section">
       <h3>System-E-Mail (SMTP)</h3>
@@ -551,6 +573,17 @@ const smtpForm = ref({
 const smtpPasswordSet = ref(false)
 const onlyofficeConfigured = ref(false)
 const onlyofficeUrl = ref('')
+const settings = ref({ timezone: '', timezone_abbr: '', server_time: '', ntp_server: '' })
+
+function formatServerTime(iso) {
+  if (!iso) return '—'
+  try {
+    return new Date(iso).toLocaleString('de-DE', {
+      day: '2-digit', month: '2-digit', year: 'numeric',
+      hour: '2-digit', minute: '2-digit', second: '2-digit',
+    })
+  } catch { return iso }
+}
 const smtpTesting = ref(false)
 
 // Backup & Restore
@@ -660,6 +693,12 @@ async function loadSettings() {
     smtpPasswordSet.value = res.data.system_smtp_password_set
     onlyofficeConfigured.value = res.data.onlyoffice_configured
     onlyofficeUrl.value = res.data.onlyoffice_url || ''
+    settings.value = {
+      timezone: res.data.timezone || '',
+      timezone_abbr: res.data.timezone_abbr || '',
+      server_time: res.data.server_time || '',
+      ntp_server: res.data.ntp_server || '',
+    }
   } catch { /* first load, defaults */ }
 }
 
@@ -1216,6 +1255,12 @@ onMounted(() => {
 .field-row { display: flex; gap: 0.75rem; align-items: flex-end; }
 .flex-grow { flex: 1; }
 .hint { font-size: 0.85rem; color: var(--p-text-muted-color); margin: 0 0 0.75rem; }
+.hint code { background: var(--p-surface-100); padding: 0.05rem 0.35rem; border-radius: 3px; font-size: 0.8rem; }
+.sysinfo { display: flex; flex-direction: column; gap: 0.4rem; font-size: 0.875rem; }
+.sysinfo-row { display: flex; gap: 0.5rem; align-items: center; flex-wrap: wrap; }
+.sysinfo-label { min-width: 180px; color: var(--p-text-muted-color); }
+.sysinfo code { background: var(--p-surface-100); padding: 0.15rem 0.5rem; border-radius: 4px; }
+.sysinfo-extra { color: var(--p-text-muted-color); font-size: 0.8rem; }
 .invite-section { margin-top: 1.5rem; padding-top: 1rem; border-top: 1px solid var(--p-surface-200); }
 .invite-section h4 { margin: 0 0 0.25rem; font-size: 0.95rem; }
 .invite-row { display: flex; gap: 0.5rem; align-items: flex-start; }

frontend/src/views/AppLayout.vue

@@ -22,6 +22,11 @@
           <span>Kontakte</span>
         </router-link>
 
+        <router-link to="/tasks" class="nav-item" active-class="active">
+          <i class="pi pi-check-square"></i>
+          <span>Aufgaben</span>
+        </router-link>
+
         <router-link
           v-if="auth.hasEmailAccounts"
           to="/email"
@@ -67,7 +72,7 @@
     </aside>
 
     <main class="main-content">
-      <router-view />
+      <router-view :key="$route.fullPath" />
     </main>
   </div>
 </template>

frontend/src/views/ClientsView.vue

@@ -0,0 +1,100 @@
+<template>
+  <div class="clients-container">
+    <div class="clients-card">
+      <div class="clients-header">
+        <i class="pi pi-cloud" style="font-size: 2rem; color: var(--p-primary-color)"></i>
+        <h1>Mini-Cloud Clients</h1>
+        <p>Lade den Sync-Client fuer dein Geraet herunter</p>
+      </div>
+
+      <div v-if="loading" class="loading">
+        <i class="pi pi-spin pi-spinner"></i> Laden...
+      </div>
+
+      <div v-else-if="!clients.length" class="empty">
+        <p>Noch keine Clients verfuegbar.</p>
+      </div>
+
+      <div v-else class="clients-grid">
+        <div v-for="client in clients" :key="client.platform" class="client-card">
+          <div class="client-icon">
+            <i :class="'pi ' + platformIcon(client.platform)"></i>
+          </div>
+          <h3>{{ client.name }}</h3>
+          <p class="client-meta">{{ client.filename }} ({{ formatSize(client.size) }})</p>
+          <Button :label="'Download ' + client.name" icon="pi pi-download"
+                  @click="downloadClient(client)" fluid />
+        </div>
+      </div>
+
+      <div class="clients-footer">
+        <router-link to="/login">Zurueck zur Anmeldung</router-link>
+      </div>
+    </div>
+  </div>
+</template>
+
+<script setup>
+import { ref, onMounted } from 'vue'
+import axios from 'axios'
+import Button from 'primevue/button'
+
+const clients = ref([])
+const loading = ref(true)
+
+const platformIcons = {
+  linux: 'pi-desktop',
+  windows: 'pi-desktop',
+  mac: 'pi-desktop',
+  android: 'pi-mobile',
+  ios: 'pi-mobile',
+}
+
+function platformIcon(platform) {
+  return platformIcons[platform] || 'pi-download'
+}
+
+function formatSize(bytes) {
+  if (!bytes) return ''
+  const units = ['B', 'KB', 'MB', 'GB']
+  let i = 0; let size = bytes
+  while (size >= 1024 && i < units.length - 1) { size /= 1024; i++ }
+  return `${size.toFixed(i > 0 ? 1 : 0)} ${units[i]}`
+}
+
+function downloadClient(client) {
+  window.location.href = `/api/clients/${client.platform}/download`
+}
+
+onMounted(async () => {
+  try {
+    const res = await axios.get('/api/clients')
+    clients.value = res.data.clients
+  } catch { clients.value = [] }
+  loading.value = false
+})
+</script>
+
+<style scoped>
+.clients-container {
+  min-height: 100vh; display: flex; align-items: center; justify-content: center;
+  background: var(--p-surface-50); padding: 1rem;
+}
+.clients-card {
+  background: var(--p-surface-0); border-radius: 12px; padding: 2.5rem;
+  max-width: 700px; width: 100%; box-shadow: 0 2px 12px rgba(0,0,0,0.08);
+}
+.clients-header { text-align: center; margin-bottom: 2rem; }
+.clients-header h1 { font-size: 1.5rem; margin: 0.5rem 0 0.25rem; }
+.clients-header p { color: var(--p-text-muted-color); margin: 0; }
+.clients-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(200px, 1fr)); gap: 1rem; }
+.client-card {
+  border: 1px solid var(--p-surface-200); border-radius: 8px; padding: 1.25rem; text-align: center;
+}
+.client-icon { font-size: 2rem; color: var(--p-primary-color); margin-bottom: 0.5rem; }
+.client-card h3 { margin: 0 0 0.25rem; font-size: 1rem; }
+.client-meta { font-size: 0.8rem; color: var(--p-text-muted-color); margin: 0 0 1rem; }
+.loading, .empty { text-align: center; padding: 2rem; color: var(--p-text-muted-color); }
+.clients-footer { text-align: center; margin-top: 1.5rem; font-size: 0.875rem; }
+.clients-footer a { color: var(--p-primary-color); text-decoration: none; }
+</style>

frontend/src/views/FilesView.vue

@@ -22,7 +22,11 @@
       <div class="header-actions">
         <Button icon="pi pi-folder-plus" label="Neuer Ordner" size="small" outlined @click="showNewFolder = true" />
         <Button icon="pi pi-upload" label="Dateien" size="small" @click="triggerUpload" />
-        <Button icon="pi pi-folder" label="Ordner" size="small" outlined @click="triggerFolderUpload" />
+        <Button size="small" outlined @click="triggerFolderUpload">
+          <i class="pi pi-upload" style="margin-right:0.35rem"></i>
+          <i class="pi pi-folder" style="margin-right:0.5rem"></i>
+          Ordner
+        </Button>
         <input ref="fileInput" type="file" multiple hidden @change="handleUpload" />
         <input ref="folderInput" type="file" hidden webkitdirectory @change="handleFolderUpload" />
       </div>
@@ -58,6 +62,9 @@
             <i :class="fileIcon(data)" class="file-icon"></i>
             <span>{{ data.name }}</span>
             <Tag v-if="data.shared" value="Geteilt" severity="info" class="shared-tag" />
+            <span v-if="data.locked" class="lock-badge" :title="'Ausgecheckt von ' + data.locked_by + ' seit ' + formatDate(data.locked_at)">
+              <i class="pi pi-lock"></i> {{ data.locked_by }}
+            </span>
           </div>
         </template>
       </Column>
@@ -91,6 +98,7 @@
               @click.stop="downloadFile(data)"
             />
             <Button
+              v-if="canShare(data)"
               :icon="(data.has_shares || data.has_permissions) ? 'pi pi-users' : 'pi pi-share-alt'"
               text rounded size="small"
               :severity="(data.has_shares || data.has_permissions) ? 'success' : undefined"
@@ -98,14 +106,33 @@
               @click.stop="openShare(data)"
             />
             <Button
+              v-if="!data.is_folder && !data.locked"
+              icon="pi pi-lock-open"
+              text rounded size="small"
+              title="Auschecken (sperren)"
+              @click.stop="lockFile(data)"
+            />
+            <Button
+              v-if="!data.is_folder && data.locked && (data.locked_by === auth.user?.username || auth.user?.role === 'admin')"
+              icon="pi pi-lock"
+              text rounded size="small"
+              severity="warn"
+              :title="data.locked_by === auth.user?.username ? 'Einchecken (entsperren)' : 'Lock zwangsweise entfernen (Admin)'"
+              @click.stop="unlockFile(data)"
+            />
+            <Button
+              v-if="canWrite(data)"
               icon="pi pi-pencil"
               text rounded size="small"
+              :disabled="data.locked && data.locked_by !== auth.user?.username"
               @click.stop="openRename(data)"
             />
             <Button
+              v-if="canWrite(data)"
               icon="pi pi-trash"
               text rounded size="small"
               severity="danger"
+              :disabled="data.locked && data.locked_by !== auth.user?.username"
               @click.stop="confirmDelete(data)"
             />
           </div>
@@ -147,9 +174,15 @@
           <h5>Mit Benutzer teilen</h5>
           <div class="user-share-row">
             <InputText v-model="shareUserQuery" placeholder="Benutzername suchen..." fluid @input="searchUsers" />
-            <Select v-model="shareUserPermission" :options="userPermOptions" optionLabel="label" optionValue="value" />
+            <Select v-model="shareUserPermission" :options="availableUserPermOptions" optionLabel="label" optionValue="value" />
+            <label class="reshare-check">
+              <input type="checkbox" v-model="shareUserReshare" /> darf weiterteilen
+            </label>
             <Button label="Teilen" size="small" @click="shareWithUser" :disabled="!selectedShareUser" />
           </div>
+          <div v-if="!isOwner(shareFile) && shareFile" class="share-hint">
+            Du hast {{ myPermLabel(shareFile) }} - du kannst maximal {{ myPermLabel(shareFile) }} weiterteilen.
+          </div>
           <div v-if="userSearchResults.length" class="user-search-results">
             <div v-for="u in userSearchResults" :key="u.id"
                  class="user-result" :class="{ selected: selectedShareUser?.id === u.id }"
@@ -158,12 +191,26 @@
             </div>
           </div>
           <div v-if="filePermissions.length" class="existing-shares">
-            <div v-for="perm in filePermissions" :key="perm.id" class="share-perm-item">
+            <template v-for="perm in filePermissions" :key="perm.id">
-              <i class="pi pi-user"></i>
+              <div v-if="editingPermId !== perm.id" class="share-perm-item">
-              <span>{{ perm.username }}</span>
+                <i class="pi pi-user"></i>
-              <Tag :value="permLabel(perm.permission)" size="small" />
+                <span>{{ perm.username }}</span>
-              <Button icon="pi pi-trash" text size="small" severity="danger" @click="removeUserShare(perm.id)" />
+                <Tag :value="permLabel(perm.permission)" size="small" />
-            </div>
+                <Tag v-if="perm.can_reshare" value="darf weiterteilen" severity="info" size="small" />
+                <Button icon="pi pi-pencil" text size="small" @click="startEditPerm(perm)" title="Bearbeiten" />
+                <Button icon="pi pi-trash" text size="small" severity="danger" @click="removeUserShare(perm.id)" title="Entfernen" />
+              </div>
+              <div v-else class="share-perm-item editing">
+                <i class="pi pi-user"></i>
+                <span>{{ perm.username }}</span>
+                <Select v-model="editPermValue" :options="availableUserPermOptions" optionLabel="label" optionValue="value" />
+                <label class="reshare-check">
+                  <input type="checkbox" v-model="editPermReshare" /> darf weiterteilen
+                </label>
+                <Button icon="pi pi-check" text size="small" severity="success" @click="saveEditPerm(perm)" title="Speichern" />
+                <Button icon="pi pi-times" text size="small" @click="cancelEditPerm" title="Abbrechen" />
+              </div>
+            </template>
           </div>
         </div>
 
@@ -173,7 +220,7 @@
           <div class="share-form">
             <div class="field">
               <label>Berechtigung</label>
-              <Select v-model="shareLinkPermission" :options="linkPermOptions" optionLabel="label" optionValue="value" fluid />
+              <Select v-model="shareLinkPermission" :options="availableLinkPermOptions" optionLabel="label" optionValue="value" fluid />
             </div>
             <div class="field">
               <label>Passwort (optional)</label>
@@ -221,8 +268,9 @@
 </template>
 
 <script setup>
-import { ref, watch, onMounted } from 'vue'
+import { ref, computed, watch, onMounted, onUnmounted } from 'vue'
 import { useRoute, useRouter } from 'vue-router'
+import { useAuthStore } from '../stores/auth'
 import { useFilesStore } from '../stores/files'
 import { useToast } from 'primevue/usetoast'
 import apiClient from '../api/client'
@@ -238,6 +286,7 @@ import ProgressBar from 'primevue/progressbar'
 
 const route = useRoute()
 const router = useRouter()
+const auth = useAuthStore()
 const filesStore = useFilesStore()
 const toast = useToast()
 
@@ -262,6 +311,10 @@ const filePermissions = ref([])
 const shareUserQuery = ref('')
 const selectedShareUser = ref(null)
 const shareUserPermission = ref('read')
+const shareUserReshare = ref(false)
+const editingPermId = ref(null)
+const editPermValue = ref('read')
+const editPermReshare = ref(false)
 const userSearchResults = ref([])
 const userPermOptions = [{ label: 'Lesen', value: 'read' }, { label: 'Schreiben', value: 'write' }, { label: 'Admin', value: 'admin' }]
 const linkPermOptions = [
@@ -269,6 +322,12 @@ const linkPermOptions = [
   { label: 'Lesen + Hochladen (nur Ordner)', value: 'write' },
   { label: 'Nur Upload (Ordner, kein Einblick)', value: 'upload_only' },
 ]
+const availableLinkPermOptions = computed(() => {
+  const f = shareFile.value
+  if (!f || isOwner(f)) return linkPermOptions
+  if (f.my_permission === 'read') return linkPermOptions.filter(o => o.value === 'read')
+  return linkPermOptions
+})
 const shareLinkPermission = ref('read')
 const currentOrigin = window.location.origin
 const shareLoading = ref(false)
@@ -298,6 +357,15 @@ function handleDoubleClick(event) {
 }
 
 function openPreview(data) {
+  if (data.locked && data.locked_by !== auth.user?.username) {
+    toast.add({
+      severity: 'warn',
+      summary: 'Datei gesperrt',
+      detail: `${data.name} wird von ${data.locked_by} bearbeitet. Oeffnen nicht moeglich.`,
+      life: 5000,
+    })
+    return
+  }
   const previewable = /\.(pdf|docx?|xlsx?|pptx?|txt|md|json|xml|csv|py|js|html|css|yml|yaml|png|jpe?g|gif|svg|webp|bmp|odt|ods|odp|rtf)$/i
   if (previewable.test(data.name)) {
     router.push(`/preview/${data.id}`)
@@ -539,6 +607,37 @@ function permLabel(perm) {
   return { read: 'Lesen', write: 'Schreiben', admin: 'Admin' }[perm] || perm
 }
 
+function isOwner(data) {
+  return data && data.owner_id === auth.user?.id
+}
+
+function canWrite(data) {
+  if (!data) return false
+  if (isOwner(data)) return true
+  return data.my_permission === 'write' || data.my_permission === 'admin'
+}
+
+function canShare(data) {
+  if (!data) return false
+  if (isOwner(data)) return true
+  return !!data.my_can_reshare
+}
+
+function myPermLabel(data) {
+  if (!data || !data.my_permission) return ''
+  return permLabel(data.my_permission)
+}
+
+// Option list for the "Mit Benutzer teilen" dropdown - re-sharers can only
+// hand out permissions up to their own level. Admin is owner-only.
+const availableUserPermOptions = computed(() => {
+  const f = shareFile.value
+  const levels = { read: 0, write: 1, admin: 2 }
+  if (!f || isOwner(f)) return userPermOptions
+  const myLevel = levels[f.my_permission] ?? -1
+  return userPermOptions.filter(o => levels[o.value] <= myLevel && o.value !== 'admin')
+})
+
 async function openShare(data) {
   shareFile.value = data
   sharePassword.value = ''
@@ -580,10 +679,12 @@ async function shareWithUser() {
     await apiClient.post(`/files/${shareFile.value.id}/permissions`, {
       user_id: selectedShareUser.value.id,
       permission: shareUserPermission.value,
+      can_reshare: shareUserReshare.value,
     })
     toast.add({ severity: 'success', summary: `Mit ${selectedShareUser.value.username} geteilt`, life: 3000 })
     shareUserQuery.value = ''
     selectedShareUser.value = null
+    shareUserReshare.value = false
     const res = await apiClient.get(`/files/${shareFile.value.id}/permissions`)
     filePermissions.value = res.data
     await filesStore.loadFiles(currentParentId())
@@ -603,6 +704,34 @@ async function removeUserShare(permId) {
   }
 }
 
+function startEditPerm(perm) {
+  editingPermId.value = perm.id
+  editPermValue.value = perm.permission
+  editPermReshare.value = !!perm.can_reshare
+}
+
+function cancelEditPerm() {
+  editingPermId.value = null
+}
+
+async function saveEditPerm(perm) {
+  if (!shareFile.value) return
+  try {
+    await apiClient.post(`/files/${shareFile.value.id}/permissions`, {
+      user_id: perm.user_id,
+      permission: editPermValue.value,
+      can_reshare: editPermReshare.value,
+    })
+    const res = await apiClient.get(`/files/${shareFile.value.id}/permissions`)
+    filePermissions.value = res.data
+    editingPermId.value = null
+    toast.add({ severity: 'success', summary: 'Berechtigung aktualisiert', life: 2500 })
+    await filesStore.loadFiles(currentParentId())
+  } catch (err) {
+    toast.add({ severity: 'error', summary: 'Fehler', detail: err.response?.data?.error || err.message, life: 5000 })
+  }
+}
+
 async function createShare() {
   console.log('createShare called, shareFile:', shareFile.value?.id, 'permission:', shareLinkPermission.value)
   if (!shareFile.value) {
@@ -645,6 +774,28 @@ async function removeShare(token) {
   }
 }
 
+async function lockFile(data) {
+  try {
+    await apiClient.post(`/files/${data.id}/lock`, { client_info: 'Web-GUI' })
+    toast.add({ severity: 'success', summary: 'Ausgecheckt', detail: `${data.name} ist jetzt fuer dich gesperrt.`, life: 3000 })
+    await filesStore.loadFiles(currentParentId())
+  } catch (err) {
+    toast.add({ severity: 'error', summary: 'Sperren fehlgeschlagen', detail: err.response?.data?.error || err.message, life: 5000 })
+  }
+}
+
+async function unlockFile(data) {
+  const isAdminOverride = data.locked_by !== auth.user?.username
+  if (isAdminOverride && !confirm(`Den Lock von ${data.locked_by} zwangsweise entfernen?`)) return
+  try {
+    await apiClient.post(`/files/${data.id}/unlock`)
+    toast.add({ severity: 'success', summary: 'Eingecheckt', detail: `${data.name} ist wieder frei.`, life: 3000 })
+    await filesStore.loadFiles(currentParentId())
+  } catch (err) {
+    toast.add({ severity: 'error', summary: 'Entsperren fehlgeschlagen', detail: err.response?.data?.error || err.message, life: 5000 })
+  }
+}
+
 function confirmDelete(data) {
   deleteTarget.value = data
   showDeleteConfirm.value = true
@@ -661,12 +812,64 @@ async function doDelete() {
   }
 }
 
+async function safeLoadCurrentFolder() {
+  try {
+    await filesStore.loadFiles(currentParentId())
+  } catch (err) {
+    const status = err.response?.status
+    if (status === 403 || status === 404) {
+      toast.add({
+        severity: 'warn',
+        summary: 'Kein Zugriff',
+        detail: 'Dieser Ordner wurde geloescht oder die Freigabe wurde entfernt.',
+        life: 5000,
+      })
+      // Redirect to root after short delay so user sees the toast
+      setTimeout(() => router.push('/files'), 600)
+    }
+  }
+}
+
 watch(() => route.params.folderId, () => {
-  filesStore.loadFiles(currentParentId())
+  safeLoadCurrentFolder()
 })
 
+// Live updates: subscribe to server-sent events so that lock changes /
+// uploads / deletions by other users or clients refresh the current
+// folder automatically.
+let eventSource = null
+let reloadDebounce = null
+
+function scheduleReload() {
+  if (reloadDebounce) return
+  reloadDebounce = setTimeout(() => {
+    reloadDebounce = null
+    safeLoadCurrentFolder()
+  }, 300)
+}
+
 onMounted(() => {
-  filesStore.loadFiles(currentParentId())
+  safeLoadCurrentFolder()
+
+  if (auth.accessToken) {
+    const url = `/api/sync/events?token=${encodeURIComponent(auth.accessToken)}`
+    try {
+      eventSource = new EventSource(url)
+      const handler = () => scheduleReload()
+      // Any named event from the server triggers a reload. Using onmessage
+      // alone misses typed events (event: file), so we wrap addEventListener
+      // into a tiny catch-all by hooking the generic EventSource dispatch.
+      eventSource.addEventListener('file', handler)
+      eventSource.addEventListener('message', handler)
+      eventSource.addEventListener('open', () => scheduleReload())
+      eventSource.onerror = () => { /* browser auto-reconnects */ }
+    } catch { /* SSE not available - fall back to manual refresh */ }
+  }
+})
+
+onUnmounted(() => {
+  if (reloadDebounce) { clearTimeout(reloadDebounce); reloadDebounce = null }
+  if (eventSource) { eventSource.close(); eventSource = null }
 })
 </script>
 
@@ -706,6 +909,12 @@ onMounted(() => {
 }
 .file-icon { font-size: 1.125rem; width: 1.25rem; text-align: center; }
 .shared-tag { font-size: 0.7rem; }
+.lock-badge {
+  display: inline-flex; align-items: center; gap: 0.25rem;
+  font-size: 0.7rem; color: var(--p-orange-600); background: var(--p-orange-50);
+  padding: 0.125rem 0.375rem; border-radius: 4px; margin-left: 0.25rem;
+}
+.lock-badge i { font-size: 0.65rem; }
 .row-actions { display: flex; gap: 0; }
 .empty-state {
   display: flex; flex-direction: column; align-items: center;
@@ -718,12 +927,15 @@ onMounted(() => {
 .share-section:last-child { border-bottom: none; }
 .share-section h5 { margin: 0 0 0.75rem; font-size: 0.9rem; }
 .share-form { }
-.user-share-row { display: flex; gap: 0.5rem; align-items: flex-start; }
+.user-share-row { display: flex; gap: 0.5rem; align-items: center; flex-wrap: wrap; }
+.reshare-check { display: flex; align-items: center; gap: 0.25rem; font-size: 0.8rem; white-space: nowrap; }
+.share-hint { font-size: 0.75rem; color: var(--p-surface-500); margin-top: 0.35rem; font-style: italic; }
 .user-search-results { border: 1px solid var(--p-surface-200); border-radius: 6px; margin-top: 0.25rem; max-height: 150px; overflow-y: auto; }
 .user-result { padding: 0.5rem 0.75rem; cursor: pointer; display: flex; align-items: center; gap: 0.5rem; font-size: 0.875rem; }
 .user-result:hover, .user-result.selected { background: var(--p-primary-50); }
 .existing-shares { margin-top: 0.5rem; }
-.share-perm-item { display: flex; align-items: center; gap: 0.5rem; padding: 0.375rem 0; font-size: 0.875rem; }
+.share-perm-item { display: flex; align-items: center; gap: 0.5rem; padding: 0.375rem 0; font-size: 0.875rem; flex-wrap: wrap; }
+.share-perm-item.editing { background: var(--p-surface-50); padding: 0.5rem; border-radius: 4px; }
 .share-link-item {
   display: flex; justify-content: space-between; align-items: center;
   padding: 0.5rem 0; border-bottom: 1px solid var(--p-surface-100);

frontend/src/views/LoginView.vue

@@ -46,6 +46,9 @@
       <div v-if="registrationAllowed" class="auth-footer">
         <router-link to="/register">Noch kein Konto? Registrieren</router-link>
       </div>
+      <div v-if="hasClients" class="auth-footer">
+        <router-link to="/clients"><i class="pi pi-download"></i> Desktop & Mobile Clients herunterladen</router-link>
+      </div>
     </div>
   </div>
 </template>
@@ -68,12 +71,17 @@ const password = ref('')
 const error = ref('')
 const loading = ref(false)
 const registrationAllowed = ref(false)
+const hasClients = ref(false)
 
 onMounted(async () => {
   try {
     const res = await axios.get('/api/auth/registration-status')
     registrationAllowed.value = res.data.allowed
   } catch { registrationAllowed.value = false }
+  try {
+    const res = await axios.get('/api/clients')
+    hasClients.value = res.data.has_clients
+  } catch { hasClients.value = false }
 })
 
 async function handleLogin() {

frontend/src/views/PasswordsView.vue

@@ -29,9 +29,22 @@
           <InputText v-model="searchQuery" placeholder="Passwoerter suchen..." fluid />
         </div>
 
+        <div v-if="filteredEntries.length" class="selection-bar">
+          <Checkbox v-model="allSelected" :binary="true" @change="toggleSelectAll" inputId="select-all" />
+          <label for="select-all" class="select-all-label">
+            Alle auswaehlen
+            <span v-if="selectedIds.length" class="selected-count">({{ selectedIds.length }} ausgewaehlt)</span>
+          </label>
+          <Button v-if="selectedIds.length" icon="pi pi-trash" :label="`${selectedIds.length} loeschen`"
+                  severity="danger" size="small" @click="deleteSelected" />
+        </div>
+
         <div class="entries-list">
           <div v-for="entry in filteredEntries" :key="entry.id"
-               class="entry-item" @click="openEntry(entry)">
+               class="entry-item" :class="{ selected: selectedIds.includes(entry.id) }"
+               @click="openEntry(entry)">
+            <Checkbox :modelValue="selectedIds.includes(entry.id)" :binary="true"
+                      @click.stop @update:modelValue="toggleSelect(entry.id)" />
             <div class="entry-icon">
               <i class="pi pi-key"></i>
             </div>
@@ -166,6 +179,7 @@ import InputText from 'primevue/inputtext'
 import Password from 'primevue/password'
 import Textarea from 'primevue/textarea'
 import Select from 'primevue/select'
+import Checkbox from 'primevue/checkbox'
 
 const toast = useToast()
 const auth = useAuthStore()
@@ -200,6 +214,45 @@ const importAccept = computed(() => {
 const showTotpDialog = ref(false)
 const totpCode = ref('')
 
+const selectedIds = ref([])
+const allSelected = computed({
+  get: () => filteredEntries.value.length > 0 && filteredEntries.value.every(e => selectedIds.value.includes(e.id)),
+  set: () => {},
+})
+
+function toggleSelectAll() {
+  const visibleIds = filteredEntries.value.map(e => e.id)
+  const allSel = visibleIds.every(id => selectedIds.value.includes(id))
+  if (allSel) {
+    selectedIds.value = selectedIds.value.filter(id => !visibleIds.includes(id))
+  } else {
+    const set = new Set([...selectedIds.value, ...visibleIds])
+    selectedIds.value = [...set]
+  }
+}
+
+function toggleSelect(id) {
+  const i = selectedIds.value.indexOf(id)
+  if (i >= 0) selectedIds.value.splice(i, 1)
+  else selectedIds.value.push(id)
+}
+
+async function deleteSelected() {
+  const n = selectedIds.value.length
+  if (!n) return
+  if (!window.confirm(`${n} Eintrag/Eintraege wirklich loeschen?`)) return
+  let ok = 0
+  for (const id of [...selectedIds.value]) {
+    try {
+      await apiClient.delete(`/passwords/entries/${id}`)
+      ok++
+    } catch { /* skip */ }
+  }
+  selectedIds.value = []
+  toast.add({ severity: 'success', summary: `${ok} Eintrag/Eintraege geloescht`, life: 3000 })
+  await loadEntries()
+}
+
 const folderOptions = computed(() => [{ id: null, name: '(Kein Ordner)' }, ...folders.value])
 const filteredEntries = computed(() => {
   if (!searchQuery.value) return entries.value
@@ -491,6 +544,10 @@ onMounted(async () => {
 .shared-label { color: var(--p-text-muted-color); font-size: 0.75rem; }
 .entries-main { flex: 1; }
 .search-bar { margin-bottom: 1rem; }
+.selection-bar { display: flex; align-items: center; gap: 0.75rem; padding: 0.5rem 0.75rem; margin-bottom: 0.5rem; background: var(--p-surface-50); border-radius: 6px; }
+.select-all-label { font-size: 0.875rem; cursor: pointer; flex: 1; }
+.selected-count { color: var(--p-text-muted-color); margin-left: 0.5rem; }
+.entry-item.selected { background: var(--p-primary-50); }
 .entries-list { display: flex; flex-direction: column; gap: 2px; }
 .entry-item { display: flex; align-items: center; gap: 0.75rem; padding: 0.75rem; background: var(--p-surface-0); border-radius: 6px; cursor: pointer; }
 .entry-item:hover { background: var(--p-surface-100); }

frontend/src/views/PreviewView.vue

@@ -104,6 +104,7 @@ const auth = useAuthStore()
 const toast = useToast()
 
 const fileId = route.params.fileId
+const cacheBust = Date.now()
 const fileName = ref('')
 const previewType = ref('')
 const previewUrl = ref('')
@@ -135,12 +136,12 @@ async function loadPreview() {
   loading.value = true
   try {
     // For Office files, try OnlyOffice first
-    const previewRes = await apiClient.get(`/files/${fileId}/preview`)
+    const previewRes = await apiClient.get(`/files/${fileId}/preview?_=${cacheBust}`)
     fileName.value = previewRes.data.name || ''
 
     if (isOfficeFile(fileName.value)) {
       try {
-        const ooRes = await apiClient.get(`/files/${fileId}/onlyoffice-config`)
+        const ooRes = await apiClient.get(`/files/${fileId}/onlyoffice-config?_=${cacheBust}`)
         if (ooRes.data.available) {
           onlyOfficeMode.value = true
           loading.value = false
@@ -156,7 +157,7 @@ async function loadPreview() {
     previewType.value = data.type
 
     if (data.type === 'pdf' || data.type === 'image') {
-      previewUrl.value = getTokenUrl(`/api/files/${fileId}/download`)
+      previewUrl.value = getTokenUrl(`/api/files/${fileId}/download?inline=1`)
       canEdit.value = false
     } else if (data.type === 'html') {
       htmlContent.value = data.content

frontend/src/views/SettingsView.vue

@@ -12,15 +12,31 @@
           <span class="label">Benutzername:</span>
           <span>{{ auth.user?.username }}</span>
         </div>
-        <div class="info-row">
-          <span class="label">E-Mail:</span>
-          <span>{{ auth.user?.email || 'Nicht angegeben' }}</span>
-        </div>
         <div class="info-row">
           <span class="label">Rolle:</span>
           <Tag :value="auth.user?.role" :severity="auth.user?.role === 'admin' ? 'danger' : 'info'" />
         </div>
       </div>
+      <p class="hint" style="margin:0.75rem 0 0.5rem;font-size:0.8rem;color:var(--p-text-muted-color)">
+        Vor- und Nachname werden anderen Benutzern angezeigt, wenn du etwas mit ihnen teilst.
+      </p>
+      <form @submit.prevent="saveProfile" class="profile-form">
+        <div class="field-row">
+          <div class="field">
+            <label>Vorname</label>
+            <InputText v-model="profile.first_name" fluid />
+          </div>
+          <div class="field">
+            <label>Nachname</label>
+            <InputText v-model="profile.last_name" fluid />
+          </div>
+        </div>
+        <div class="field">
+          <label>E-Mail</label>
+          <InputText v-model="profile.email" type="email" fluid />
+        </div>
+        <Button type="submit" label="Profil speichern" :loading="profileLoading" size="small" />
+      </form>
     </div>
 
     <!-- Change Password -->
@@ -45,6 +61,24 @@
       </form>
     </div>
 
+    <!-- Client Downloads -->
+    <div v-if="availableClients.length" class="settings-section">
+      <h3>Desktop & Mobile Clients</h3>
+      <div class="client-list">
+        <div v-for="client in availableClients" :key="client.platform" class="client-item">
+          <div class="client-info">
+            <i :class="'pi ' + (client.platform === 'linux' || client.platform === 'windows' || client.platform === 'mac' ? 'pi-desktop' : 'pi-mobile')"></i>
+            <div>
+              <strong>{{ client.name }}</strong>
+              <span class="client-meta">{{ client.filename }}</span>
+            </div>
+          </div>
+          <Button icon="pi pi-download" :label="'Download'" size="small" outlined
+                  @click="downloadClient(client)" />
+        </div>
+      </div>
+    </div>
+
     <!-- Email Accounts -->
     <div class="settings-section">
       <div class="section-header">
@@ -167,6 +201,43 @@ import InputSwitch from 'primevue/inputswitch'
 const auth = useAuthStore()
 const toast = useToast()
 
+// Client downloads
+const availableClients = ref([])
+
+function downloadClient(client) {
+  window.location.href = `/api/clients/${client.platform}/download`
+}
+
+// --- Profile (Vorname/Nachname/E-Mail) ---
+const profile = ref({ first_name: '', last_name: '', email: '' })
+const profileLoading = ref(false)
+
+async function loadProfile() {
+  try {
+    const res = await apiClient.get('/auth/me')
+    profile.value = {
+      first_name: res.data.first_name || '',
+      last_name: res.data.last_name || '',
+      email: res.data.email || '',
+    }
+    auth.user = { ...auth.user, ...res.data }
+  } catch { /* ignore */ }
+}
+
+async function saveProfile() {
+  profileLoading.value = true
+  try {
+    const res = await apiClient.put('/auth/me', profile.value)
+    auth.user = { ...auth.user, ...res.data }
+    toast.add({ severity: 'success', summary: 'Profil gespeichert', life: 2500 })
+  } catch (err) {
+    toast.add({ severity: 'error', summary: 'Fehler',
+                detail: err.response?.data?.error || err.message, life: 4000 })
+  } finally {
+    profileLoading.value = false
+  }
+}
+
 // --- Password change ---
 const currentPassword = ref('')
 const newPassword = ref('')
@@ -307,7 +378,14 @@ async function doDeleteAccount() {
   }
 }
 
-onMounted(loadAccounts)
+onMounted(async () => {
+  loadAccounts()
+  loadProfile()
+  try {
+    const res = await apiClient.get('/clients')
+    availableClients.value = res.data.clients
+  } catch { availableClients.value = [] }
+})
 </script>
 
 <style scoped>
@@ -321,6 +399,10 @@ onMounted(loadAccounts)
 .section-header h3 { margin: 0; }
 .settings-info { display: flex; flex-direction: column; gap: 0.5rem; }
 .info-row { display: flex; align-items: center; gap: 0.5rem; }
+.profile-form { display: flex; flex-direction: column; gap: 0.5rem; max-width: 540px; }
+.profile-form .field-row { display: flex; gap: 0.75rem; }
+.profile-form .field-row .field { flex: 1; }
+.profile-form .field label { display: block; font-size: 0.8rem; margin-bottom: 0.25rem; }
 .info-row .label { font-weight: 500; min-width: 120px; }
 .password-form { max-width: 400px; }
 .password-form .field { margin-bottom: 1rem; }
@@ -346,4 +428,12 @@ onMounted(loadAccounts)
 .field label { display: block; margin-bottom: 0.5rem; font-weight: 500; font-size: 0.875rem; }
 .field-row { display: flex; gap: 0.75rem; align-items: flex-end; }
 .flex-grow { flex: 1; }
+.client-list { display: flex; flex-direction: column; gap: 0.5rem; }
+.client-item {
+  display: flex; align-items: center; justify-content: space-between;
+  padding: 0.75rem; border: 1px solid var(--p-surface-200); border-radius: 8px;
+}
+.client-info { display: flex; align-items: center; gap: 0.75rem; }
+.client-info i { font-size: 1.25rem; color: var(--p-primary-color); }
+.client-meta { display: block; font-size: 0.8rem; color: var(--p-text-muted-color); }
 </style>

frontend/src/views/TasksView.vue

@@ -0,0 +1,773 @@
+<template>
+  <div class="view-container">
+    <div class="view-header">
+      <h2>Aufgaben</h2>
+      <div class="header-actions">
+        <Button icon="pi pi-list" label="Neue Liste" size="small" outlined @click="showNewList = true" />
+        <Button icon="pi pi-upload" label="Import" size="small" outlined @click="triggerImport" />
+        <input ref="importInput" type="file" accept=".ics,.ical,.csv" hidden @change="onImportFile" />
+        <Button icon="pi pi-download" label="Export" size="small" outlined
+                :disabled="!selectedListId" @click="showExportDialog = true" />
+        <Button icon="pi pi-plus" label="Neue Aufgabe" size="small"
+                :disabled="!writableLists.length" @click="openNewTask" />
+      </div>
+    </div>
+
+    <div class="tasks-layout">
+      <aside class="lists-sidebar">
+        <h4>Listen</h4>
+        <div v-for="tl in lists" :key="tl.id"
+             class="list-item" :class="{ active: selectedListId === tl.id }"
+             @click="selectedListId = tl.id">
+          <span class="list-color" :style="{ background: tl.color }"></span>
+          <span class="list-name">{{ tl.name }}</span>
+          <span v-if="tl.permission !== 'owner'" class="shared-label"
+                :title="`Geteilt von ${tl.owner_display_name || tl.owner_name}`">
+            (geteilt von {{ tl.owner_display_name || tl.owner_name }})
+          </span>
+          <span class="count">{{ tl.task_count }}</span>
+          <Button icon="pi pi-ellipsis-v" text size="small" class="list-menu"
+                  @click.stop="openListMenu(tl)" />
+        </div>
+      </aside>
+
+      <div class="tasks-main">
+        <div class="toolbar">
+          <InputText v-model="search" placeholder="Aufgaben suchen..." fluid />
+          <label class="toggle"><Checkbox v-model="hideDone" :binary="true" /> Erledigte ausblenden</label>
+        </div>
+
+        <div v-if="selectedTaskIds.length" class="bulk-bar">
+          <span>{{ selectedTaskIds.length }} ausgewaehlt</span>
+          <Button icon="pi pi-trash" :label="`${selectedTaskIds.length} loeschen`"
+                  severity="danger" size="small" @click="bulkDelete" />
+          <Button label="Auswahl aufheben" size="small" text @click="selectedTaskIds = []" />
+        </div>
+
+        <table class="task-table">
+          <thead>
+            <tr>
+              <th class="col-check">
+                <Checkbox v-model="allSelected" :binary="true" @change="toggleAll" />
+              </th>
+              <th class="col-done"></th>
+              <th>Titel</th>
+              <th>Faellig</th>
+              <th>Prio</th>
+              <th>Status</th>
+              <th></th>
+            </tr>
+          </thead>
+          <tbody>
+            <tr v-for="t in filteredTasks" :key="t.id" class="task-row"
+                :class="{ done: t.status === 'COMPLETED', selected: selectedTaskIds.includes(t.id) }"
+                @click="openEditTask(t)">
+              <td class="col-check" @click.stop>
+                <Checkbox :modelValue="selectedTaskIds.includes(t.id)" :binary="true"
+                          @update:modelValue="toggleSelect(t.id, $event)" />
+              </td>
+              <td class="col-done" @click.stop>
+                <Checkbox :modelValue="t.status === 'COMPLETED'" :binary="true"
+                          @update:modelValue="toggleDone(t, $event)" title="Erledigt" />
+              </td>
+              <td class="col-title">
+                <span>{{ t.summary || '(ohne Titel)' }}</span>
+                <small v-if="t.description" class="meta">{{ shortDesc(t.description) }}</small>
+              </td>
+              <td class="col-date">{{ formatDue(t.due) }}</td>
+              <td>{{ formatPrio(t.priority) }}</td>
+              <td><span class="status-badge" :class="statusClass(t.status)">{{ statusLabel(t.status) }}</span></td>
+              <td class="col-actions" @click.stop>
+                <Button icon="pi pi-trash" text size="small" severity="danger" @click="confirmDelete(t)" />
+              </td>
+            </tr>
+            <tr v-if="!filteredTasks.length">
+              <td colspan="7" class="empty-row">Keine Aufgaben.</td>
+            </tr>
+          </tbody>
+        </table>
+      </div>
+    </div>
+
+    <!-- New List Dialog -->
+    <Dialog v-model:visible="showNewList" header="Neue Aufgabenliste" modal :style="{ width: '400px' }">
+      <div class="field">
+        <label>Name</label>
+        <InputText v-model="newListName" fluid autofocus @keyup.enter="createList" />
+      </div>
+      <div class="field">
+        <label>Farbe</label>
+        <InputText v-model="newListColor" type="color" style="width: 60px; height: 36px" />
+      </div>
+      <template #footer>
+        <Button label="Abbrechen" text @click="showNewList = false" />
+        <Button label="Erstellen" @click="createList" />
+      </template>
+    </Dialog>
+
+    <!-- List Menu -->
+    <Dialog v-model:visible="showListMenu" header="Listen-Optionen" modal :style="{ width: '480px' }">
+      <div v-if="menuList">
+        <div class="rename-row">
+          <template v-if="!isRenaming">
+            <strong>{{ menuList.name }}</strong>
+            <Button v-if="menuList.permission === 'owner'"
+                    icon="pi pi-pencil" text size="small" title="Umbenennen"
+                    @click="startRename" />
+          </template>
+          <template v-else>
+            <InputText v-model="renameValue" fluid autofocus
+                       @keyup.enter="saveRename" @keyup.escape="isRenaming = false" />
+            <Button icon="pi pi-check" text size="small" severity="success"
+                    title="Speichern" @click="saveRename" />
+            <Button icon="pi pi-times" text size="small"
+                    title="Abbrechen" @click="isRenaming = false" />
+          </template>
+        </div>
+        <div class="field">
+          <label>Farbe</label>
+          <InputText :modelValue="menuList.color" @change="onListColor($event)" type="color" style="width:60px; height:36px" />
+        </div>
+        <div v-if="menuList.permission === 'owner'" class="field">
+          <label>Mit Benutzer teilen</label>
+          <div class="share-row">
+            <div style="position: relative; flex: 1;">
+              <InputText v-model="shareUsername" placeholder="Benutzername suchen..."
+                         fluid @input="onShareSearch" />
+              <div v-if="shareSearchResults.length" class="user-search-popup">
+                <div v-for="u in shareSearchResults" :key="u.id" class="user-result"
+                     @click="shareUsername = u.username; shareSearchResults = []">
+                  <i class="pi pi-user"></i>
+                  <span>{{ u.username }}</span>
+                  <small v-if="u.full_name" class="user-fullname">{{ u.full_name }}</small>
+                </div>
+              </div>
+            </div>
+            <Select v-model="sharePermission" :options="permOptions" optionLabel="label" optionValue="value" />
+            <Button label="Teilen" size="small" @click="doShare" />
+          </div>
+          <div v-if="listShares.length" class="existing-shares">
+            <template v-for="s in listShares" :key="s.id">
+              <div v-if="editingShareId !== s.id" class="share-perm-item">
+                <i class="pi pi-user"></i> <span>{{ s.username }}</span>
+                <span class="perm-label">{{ s.permission === 'readwrite' ? 'Lesen+Schreiben' : 'Lesen' }}</span>
+                <Button icon="pi pi-pencil" text size="small" title="Bearbeiten" @click="startEditShare(s)" />
+                <Button icon="pi pi-trash" text size="small" severity="danger" title="Entfernen" @click="removeShare(s.id)" />
+              </div>
+              <div v-else class="share-perm-item editing">
+                <i class="pi pi-user"></i> <span>{{ s.username }}</span>
+                <Select v-model="editSharePermission" :options="permOptions" optionLabel="label" optionValue="value" />
+                <Button icon="pi pi-check" text size="small" severity="success" title="Speichern" @click="saveEditShare(s)" />
+                <Button icon="pi pi-times" text size="small" title="Abbrechen" @click="editingShareId = null" />
+              </div>
+            </template>
+          </div>
+        </div>
+        <div v-if="menuList.permission === 'owner'" class="field" style="border-top:1px solid var(--p-surface-200); padding-top:1rem">
+          <Button label="Liste loeschen" severity="danger" outlined size="small" @click="confirmDeleteList = true" />
+        </div>
+        <div class="field" style="border-top:1px solid var(--p-surface-200); padding-top:1rem">
+          <label><i class="pi pi-info-circle"></i> CalDAV-Zugang (Handy / DAVx5)</label>
+          <div class="caldav-hint">In DAVx5 unter demselben Konto sichtbar wie Kalender. Aufgabenlisten sind mit "OpenTasks" synchronisierbar.</div>
+          <div class="url-row">
+            <strong>Listen-URL:</strong>
+            <code>{{ origin }}/dav/{{ username }}/tl-{{ menuList.id }}/</code>
+            <Button icon="pi pi-copy" text size="small" @click="copy(`${origin}/dav/${username}/tl-${menuList.id}/`)" />
+          </div>
+        </div>
+      </div>
+    </Dialog>
+
+    <!-- Task Dialog -->
+    <Dialog v-model:visible="showTaskDialog" :header="editingTaskId ? 'Aufgabe bearbeiten' : 'Neue Aufgabe'"
+            modal :style="{ width: '560px' }">
+      <div v-if="writableLists.length > 1" class="field">
+        <label>Liste</label>
+        <Select v-model="taskTargetListId" :options="writableListOptions"
+                optionLabel="label" optionValue="id" fluid />
+      </div>
+      <div class="field">
+        <label>Titel</label>
+        <InputText v-model="taskForm.summary" fluid autofocus />
+      </div>
+      <div class="field">
+        <label>Beschreibung</label>
+        <Textarea v-model="taskForm.description" rows="3" fluid />
+      </div>
+      <div class="field-row">
+        <div class="field">
+          <label>Faellig</label>
+          <InputText v-model="taskForm.due" type="datetime-local" fluid />
+        </div>
+        <div class="field">
+          <label>Status</label>
+          <Select v-model="taskForm.status" :options="statusOptions" optionLabel="label" optionValue="value" fluid />
+        </div>
+      </div>
+      <div class="field-row">
+        <div class="field">
+          <label>Prioritaet</label>
+          <Select v-model="taskForm.priority" :options="prioOptions" optionLabel="label" optionValue="value" fluid />
+        </div>
+        <div class="field">
+          <label>Fortschritt %</label>
+          <InputText v-model.number="taskForm.percent_complete" type="number" min="0" max="100" fluid />
+        </div>
+      </div>
+      <div class="field">
+        <label>Kategorien (kommagetrennt)</label>
+        <InputText v-model="taskForm.categories" fluid />
+      </div>
+      <template #footer>
+        <Button v-if="editingTaskId" label="Loeschen" text severity="danger" @click="deleteCurrent" />
+        <Button label="Abbrechen" text @click="showTaskDialog = false" />
+        <Button :label="editingTaskId ? 'Speichern' : 'Erstellen'" @click="saveTask" />
+      </template>
+    </Dialog>
+
+    <Dialog v-model:visible="confirmDeleteList" header="Liste loeschen" modal :style="{ width: '400px' }">
+      <p>Liste <strong>{{ menuList?.name }}</strong> mit allen Aufgaben loeschen?</p>
+      <template #footer>
+        <Button label="Abbrechen" text @click="confirmDeleteList = false" />
+        <Button label="Loeschen" severity="danger" @click="deleteList" />
+      </template>
+    </Dialog>
+
+    <!-- Export Dialog -->
+    <Dialog v-model:visible="showExportDialog" header="Aufgaben exportieren" modal :style="{ width: '420px' }">
+      <p>Aus Liste <strong>{{ currentList?.name }}</strong></p>
+      <div class="field">
+        <label>Format</label>
+        <Select v-model="exportFormat" :options="exportFormats" optionLabel="label" optionValue="value" fluid />
+      </div>
+      <template #footer>
+        <Button label="Abbrechen" text @click="showExportDialog = false" />
+        <Button label="Herunterladen" icon="pi pi-download" @click="doExport" />
+      </template>
+    </Dialog>
+  </div>
+</template>
+
+<script setup>
+import { ref, reactive, computed, onMounted, onUnmounted, watch } from 'vue'
+import { useToast } from 'primevue/usetoast'
+import { useAuthStore } from '../stores/auth'
+import apiClient from '../api/client'
+import Button from 'primevue/button'
+import Dialog from 'primevue/dialog'
+import InputText from 'primevue/inputtext'
+import Textarea from 'primevue/textarea'
+import Select from 'primevue/select'
+import Checkbox from 'primevue/checkbox'
+
+const toast = useToast()
+const auth = useAuthStore()
+const origin = computed(() => window.location.origin)
+const username = computed(() => auth.user?.username || '')
+
+const lists = ref([])
+const selectedListId = ref(null)
+const taskTargetListId = ref(null)
+const writableLists = computed(() =>
+  lists.value.filter(l => l.permission === 'owner' || l.permission === 'readwrite')
+)
+const writableListOptions = computed(() => writableLists.value.map(l => ({
+  ...l,
+  label: l.permission === 'owner'
+    ? l.name
+    : `${l.name} (geteilt von ${l.owner_display_name || l.owner_name})`,
+})))
+const tasks = ref([])
+const search = ref('')
+const hideDone = ref(false)
+const selectedTaskIds = ref([])
+
+const showNewList = ref(false)
+const newListName = ref('')
+const newListColor = ref('#10b981')
+
+const showListMenu = ref(false)
+const menuList = ref(null)
+const shareUsername = ref('')
+const sharePermission = ref('read')
+const listShares = ref([])
+const shareSearchResults = ref([])
+const editingShareId = ref(null)
+const editSharePermission = ref('read')
+const isRenaming = ref(false)
+const renameValue = ref('')
+
+function startRename() {
+  renameValue.value = menuList.value?.name || ''
+  isRenaming.value = true
+}
+
+async function saveRename() {
+  const newName = renameValue.value.trim()
+  if (!newName || !menuList.value || newName === menuList.value.name) {
+    isRenaming.value = false
+    return
+  }
+  try {
+    await apiClient.put(`/tasklists/${menuList.value.id}`, { name: newName })
+    menuList.value.name = newName
+    isRenaming.value = false
+    await loadLists()
+    toast.add({ severity: 'success', summary: 'Umbenannt', life: 2000 })
+  } catch (err) {
+    toast.add({ severity: 'error', summary: 'Fehler',
+                detail: err.response?.data?.error || err.message, life: 4000 })
+  }
+}
+let shareSearchTimer = null
+
+function startEditShare(s) {
+  editingShareId.value = s.id
+  editSharePermission.value = s.permission
+}
+
+async function saveEditShare(s) {
+  if (!menuList.value) return
+  try {
+    await apiClient.post(`/tasklists/${menuList.value.id}/share`, {
+      username: s.username,
+      permission: editSharePermission.value,
+    })
+    editingShareId.value = null
+    await loadShares()
+    toast.add({ severity: 'success', summary: 'Berechtigung aktualisiert', life: 2500 })
+  } catch (err) {
+    toast.add({ severity: 'error', summary: 'Fehler',
+                detail: err.response?.data?.error || err.message, life: 4000 })
+  }
+}
+
+function onShareSearch() {
+  clearTimeout(shareSearchTimer)
+  const q = shareUsername.value.trim()
+  if (q.length < 2) { shareSearchResults.value = []; return }
+  shareSearchTimer = setTimeout(async () => {
+    try {
+      const res = await apiClient.get('/users/search', { params: { q } })
+      shareSearchResults.value = res.data
+    } catch { shareSearchResults.value = [] }
+  }, 250)
+}
+const permOptions = [
+  { label: 'Lesen', value: 'read' },
+  { label: 'Lesen+Schreiben', value: 'readwrite' },
+]
+
+const confirmDeleteList = ref(false)
+
+const showTaskDialog = ref(false)
+const editingTaskId = ref(null)
+const taskForm = reactive({
+  summary: '', description: '',
+  due: '', status: 'NEEDS-ACTION', priority: null, percent_complete: null,
+  categories: '',
+})
+
+const statusOptions = [
+  { label: 'Offen', value: 'NEEDS-ACTION' },
+  { label: 'In Arbeit', value: 'IN-PROCESS' },
+  { label: 'Erledigt', value: 'COMPLETED' },
+  { label: 'Abgebrochen', value: 'CANCELLED' },
+]
+const prioOptions = [
+  { label: '—', value: null },
+  { label: 'Hoch (1)', value: 1 },
+  { label: 'Mittel (5)', value: 5 },
+  { label: 'Niedrig (9)', value: 9 },
+]
+
+const showExportDialog = ref(false)
+const exportFormat = ref('ics')
+const exportFormats = [
+  { label: 'iCalendar (.ics)', value: 'ics' },
+  { label: 'CSV (.csv)', value: 'csv' },
+]
+const importInput = ref(null)
+
+const currentList = computed(() => lists.value.find(l => l.id === selectedListId.value))
+
+const filteredTasks = computed(() => {
+  const q = search.value.trim().toLowerCase()
+  return tasks.value.filter(t => {
+    if (hideDone.value && t.status === 'COMPLETED') return false
+    if (q && !(t.summary || '').toLowerCase().includes(q)
+         && !(t.description || '').toLowerCase().includes(q)) return false
+    return true
+  })
+})
+
+const allSelected = computed({
+  get: () => filteredTasks.value.length > 0 && filteredTasks.value.every(t => selectedTaskIds.value.includes(t.id)),
+  set: () => {},
+})
+
+function toggleAll() {
+  const ids = filteredTasks.value.map(t => t.id)
+  const allSel = ids.every(id => selectedTaskIds.value.includes(id))
+  if (allSel) selectedTaskIds.value = selectedTaskIds.value.filter(id => !ids.includes(id))
+  else {
+    const set = new Set(selectedTaskIds.value); ids.forEach(id => set.add(id))
+    selectedTaskIds.value = [...set]
+  }
+}
+function toggleSelect(id, checked) {
+  if (checked && !selectedTaskIds.value.includes(id)) selectedTaskIds.value = [...selectedTaskIds.value, id]
+  else if (!checked) selectedTaskIds.value = selectedTaskIds.value.filter(x => x !== id)
+}
+
+function shortDesc(s) { return s.length > 80 ? s.slice(0, 80) + '…' : s }
+
+function formatDue(d) {
+  if (!d) return ''
+  return new Date(d).toLocaleString('de-DE', { day: '2-digit', month: '2-digit', year: 'numeric', hour: '2-digit', minute: '2-digit' })
+}
+function formatPrio(p) {
+  if (p === null || p === undefined) return ''
+  if (p <= 3) return 'Hoch'
+  if (p >= 7) return 'Niedrig'
+  return 'Mittel'
+}
+function statusLabel(s) {
+  return ({ 'NEEDS-ACTION': 'Offen', 'IN-PROCESS': 'In Arbeit', 'COMPLETED': 'Erledigt', 'CANCELLED': 'Abgebrochen' })[s] || 'Offen'
+}
+function statusClass(s) {
+  return { 'NEEDS-ACTION': 'todo', 'IN-PROCESS': 'progress', 'COMPLETED': 'done', 'CANCELLED': 'cancelled' }[s] || 'todo'
+}
+
+async function loadLists() {
+  const res = await apiClient.get('/tasklists')
+  lists.value = res.data
+  if (!selectedListId.value && lists.value.length) selectedListId.value = lists.value[0].id
+  if (!lists.value.length) {
+    await apiClient.post('/tasklists', { name: 'Meine Aufgaben', color: '#10b981' })
+    await loadLists()
+  }
+}
+
+async function loadTasks() {
+  if (!selectedListId.value) { tasks.value = []; return }
+  try {
+    const res = await apiClient.get(`/tasklists/${selectedListId.value}/tasks`)
+    tasks.value = res.data
+  } catch { tasks.value = [] }
+}
+
+async function createList() {
+  if (!newListName.value.trim()) return
+  await apiClient.post('/tasklists', { name: newListName.value.trim(), color: newListColor.value })
+  showNewList.value = false
+  newListName.value = ''
+  await loadLists()
+}
+
+function openListMenu(tl) {
+  menuList.value = tl
+  shareUsername.value = ''
+  shareSearchResults.value = []
+  isRenaming.value = false
+  showListMenu.value = true
+  loadShares()
+}
+
+async function loadShares() {
+  if (!menuList.value || menuList.value.permission !== 'owner') { listShares.value = []; return }
+  try {
+    const res = await apiClient.get(`/tasklists/${menuList.value.id}/shares`)
+    listShares.value = res.data
+  } catch { listShares.value = [] }
+}
+
+async function doShare() {
+  if (!menuList.value || !shareUsername.value.trim()) return
+  try {
+    await apiClient.post(`/tasklists/${menuList.value.id}/share`, {
+      username: shareUsername.value.trim(), permission: sharePermission.value,
+    })
+    toast.add({ severity: 'success', summary: 'Geteilt', life: 2500 })
+    shareUsername.value = ''
+    shareSearchResults.value = []
+    await loadShares()
+  } catch (err) {
+    toast.add({ severity: 'error', summary: err.response?.data?.error || 'Fehler', life: 4000 })
+  }
+}
+
+async function removeShare(id) {
+  await apiClient.delete(`/tasklists/${menuList.value.id}/shares/${id}`)
+  await loadShares()
+}
+
+async function onListColor(ev) {
+  const color = ev.target.value
+  await apiClient.put(`/tasklists/${menuList.value.id}/my-color`, { color })
+  menuList.value.color = color
+  await loadLists()
+}
+
+async function deleteList() {
+  if (!menuList.value) return
+  await apiClient.delete(`/tasklists/${menuList.value.id}`)
+  confirmDeleteList.value = false
+  showListMenu.value = false
+  if (selectedListId.value === menuList.value.id) selectedListId.value = null
+  await loadLists()
+  await loadTasks()
+}
+
+function openNewTask() {
+  if (!writableLists.value.length) {
+    toast.add({ severity: 'warn', summary: 'Keine beschreibbare Liste', life: 3000 })
+    return
+  }
+  editingTaskId.value = null
+  Object.assign(taskForm, {
+    summary: '', description: '', due: '',
+    status: 'NEEDS-ACTION', priority: null, percent_complete: null,
+    categories: '',
+  })
+  // Default-Liste: aktuell markierte falls beschreibbar, sonst erste beschreibbare
+  const sel = writableLists.value.find(l => l.id === selectedListId.value)
+  taskTargetListId.value = sel ? sel.id : writableLists.value[0].id
+  showTaskDialog.value = true
+}
+
+function openEditTask(t) {
+  editingTaskId.value = t.id
+  Object.assign(taskForm, {
+    summary: t.summary || '',
+    description: t.description || '',
+    due: t.due ? t.due.slice(0, 16) : '',
+    status: t.status || 'NEEDS-ACTION',
+    priority: t.priority,
+    percent_complete: t.percent_complete,
+    categories: (t.categories || []).join(', '),
+  })
+  showTaskDialog.value = true
+}
+
+async function saveTask() {
+  if (!taskForm.summary.trim()) return
+  const payload = {
+    summary: taskForm.summary.trim(),
+    description: taskForm.description,
+    due: taskForm.due ? new Date(taskForm.due).toISOString() : null,
+    status: taskForm.status,
+    priority: taskForm.priority,
+    percent_complete: taskForm.percent_complete,
+    categories: taskForm.categories.split(',').map(s => s.trim()).filter(Boolean),
+  }
+  try {
+    if (editingTaskId.value) {
+      await apiClient.put(`/tasks/${editingTaskId.value}`, payload)
+    } else {
+      const target = taskTargetListId.value || selectedListId.value
+      if (!target) {
+        toast.add({ severity: 'error', summary: 'Bitte Liste waehlen', life: 3000 })
+        return
+      }
+      await apiClient.post(`/tasklists/${target}/tasks`, payload)
+    }
+    showTaskDialog.value = false
+    await loadLists()
+    await loadTasks()
+  } catch (err) {
+    toast.add({ severity: 'error', summary: 'Fehler', detail: err.response?.data?.error, life: 4000 })
+  }
+}
+
+async function toggleDone(t, checked) {
+  try {
+    await apiClient.put(`/tasks/${t.id}`, { status: checked ? 'COMPLETED' : 'NEEDS-ACTION' })
+    await loadTasks()
+  } catch (err) {
+    toast.add({ severity: 'error', summary: 'Fehler', life: 3000 })
+  }
+}
+
+async function deleteCurrent() {
+  if (!editingTaskId.value) return
+  if (!confirm('Aufgabe wirklich loeschen?')) return
+  await apiClient.delete(`/tasks/${editingTaskId.value}`)
+  showTaskDialog.value = false
+  await loadLists()
+  await loadTasks()
+}
+
+async function confirmDelete(t) {
+  if (!confirm(`"${t.summary || '(ohne Titel)'}" loeschen?`)) return
+  await apiClient.delete(`/tasks/${t.id}`)
+  await loadLists()
+  await loadTasks()
+}
+
+async function bulkDelete() {
+  const ids = [...selectedTaskIds.value]
+  if (!ids.length || !confirm(`${ids.length} Aufgabe(n) loeschen?`)) return
+  let ok = 0, fail = 0
+  for (const id of ids) {
+    try { await apiClient.delete(`/tasks/${id}`); ok++ } catch { fail++ }
+  }
+  selectedTaskIds.value = []
+  toast.add({
+    severity: fail ? 'warn' : 'success',
+    summary: `${ok} geloescht${fail ? `, ${fail} fehlgeschlagen` : ''}`, life: 3000,
+  })
+  await loadLists()
+  await loadTasks()
+}
+
+function triggerImport() {
+  if (!selectedListId.value) {
+    toast.add({ severity: 'warn', summary: 'Keine Liste ausgewaehlt', life: 3000 })
+    return
+  }
+  importInput.value?.click()
+}
+
+async function onImportFile(ev) {
+  const file = ev.target.files?.[0]
+  ev.target.value = ''
+  if (!file) return
+  const fd = new FormData()
+  fd.append('file', file)
+  try {
+    const res = await apiClient.post(`/tasklists/${selectedListId.value}/import`, fd,
+      { headers: { 'Content-Type': 'multipart/form-data' } })
+    toast.add({
+      severity: 'success',
+      summary: `${res.data.imported} importiert`,
+      detail: res.data.skipped ? `${res.data.skipped} uebersprungen` : undefined,
+      life: 4000,
+    })
+    await loadLists()
+    await loadTasks()
+  } catch (err) {
+    toast.add({ severity: 'error', summary: 'Import fehlgeschlagen', detail: err.response?.data?.error, life: 5000 })
+  }
+}
+
+async function doExport() {
+  if (!selectedListId.value) return
+  try {
+    const res = await apiClient.get(`/tasklists/${selectedListId.value}/export`,
+      { params: { format: exportFormat.value }, responseType: 'blob' })
+    const ext = exportFormat.value === 'csv' ? 'csv' : 'ics'
+    const url = URL.createObjectURL(new Blob([res.data]))
+    const a = document.createElement('a')
+    a.href = url
+    a.download = `${currentList.value?.name || 'aufgaben'}.${ext}`
+    a.click()
+    URL.revokeObjectURL(url)
+    showExportDialog.value = false
+  } catch (err) {
+    toast.add({ severity: 'error', summary: 'Export fehlgeschlagen', life: 4000 })
+  }
+}
+
+function copy(text) {
+  navigator.clipboard.writeText(text)
+  toast.add({ severity: 'info', summary: 'Kopiert', life: 1500 })
+}
+
+// --- Live refresh via SSE ---
+let eventSource = null
+let reloadTimer = null
+function scheduleReload() {
+  if (reloadTimer) return
+  reloadTimer = setTimeout(async () => {
+    reloadTimer = null
+    await loadLists()
+    await loadTasks()
+  }, 300)
+}
+
+onMounted(async () => {
+  await loadLists()
+  await loadTasks()
+  if (auth.accessToken) {
+    try {
+      eventSource = new EventSource(`/api/sync/events?token=${encodeURIComponent(auth.accessToken)}`)
+      eventSource.addEventListener('tasklist', scheduleReload)
+      eventSource.addEventListener('message', scheduleReload)
+      eventSource.onerror = () => {}
+    } catch {}
+  }
+})
+onUnmounted(() => {
+  if (reloadTimer) clearTimeout(reloadTimer)
+  if (eventSource) eventSource.close()
+})
+
+watch(selectedListId, loadTasks)
+</script>
+
+<style scoped>
+.view-container { padding: 1.5rem; }
+.view-header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 1rem; }
+.view-header h2 { margin: 0; }
+.header-actions { display: flex; gap: 0.5rem; }
+.tasks-layout { display: flex; gap: 1rem; align-items: flex-start; }
+.lists-sidebar { width: 260px; flex-shrink: 0; }
+.lists-sidebar h4 { margin: 0 0 0.5rem; font-size: 0.85rem; text-transform: uppercase; color: var(--p-text-muted-color); }
+.list-item { display: flex; align-items: center; gap: 0.5rem; padding: 0.5rem; border-radius: 4px;
+             cursor: pointer; font-size: 0.875rem; }
+.list-item:hover { background: var(--p-surface-50); }
+.list-item.active { background: var(--p-primary-50); }
+.list-color { width: 12px; height: 12px; border-radius: 3px; flex-shrink: 0; }
+.list-name { flex: 1; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
+.shared-label { color: var(--p-text-muted-color); font-size: 0.7rem; }
+.count { color: var(--p-text-muted-color); font-size: 0.8rem; }
+.list-menu { opacity: 0; transition: opacity .15s; }
+.list-item:hover .list-menu { opacity: 1; }
+.tasks-main { flex: 1; min-width: 0; }
+.toolbar { display: flex; gap: 0.75rem; align-items: center; margin-bottom: 0.75rem; }
+.toggle { display: flex; align-items: center; gap: 0.35rem; font-size: 0.875rem; white-space: nowrap; }
+.bulk-bar { display: flex; gap: 0.5rem; align-items: center; padding: 0.5rem 0.75rem;
+            background: var(--p-primary-50); border-radius: 6px; margin-bottom: 0.5rem; font-size: 0.875rem; }
+.task-table { width: 100%; border-collapse: collapse; font-size: 0.875rem; }
+.task-table th { text-align: left; padding: 0.5rem; border-bottom: 2px solid var(--p-surface-200); font-weight: 600; }
+.task-table td { padding: 0.5rem; border-bottom: 1px solid var(--p-surface-100); vertical-align: top; }
+.task-row { cursor: pointer; }
+.task-row:hover { background: var(--p-surface-50); }
+.task-row.done .col-title span { text-decoration: line-through; color: var(--p-text-muted-color); }
+.task-row.selected { background: var(--p-primary-50); }
+.col-check, .col-done { width: 36px; }
+.col-actions { width: 60px; text-align: right; }
+.col-date { white-space: nowrap; }
+.col-title { }
+.meta { display: block; color: var(--p-text-muted-color); font-size: 0.75rem; margin-top: 0.1rem; }
+.empty-row { text-align: center; color: var(--p-text-muted-color); padding: 2rem !important; }
+.status-badge { display: inline-block; padding: 0.15rem 0.5rem; border-radius: 10px; font-size: 0.72rem; }
+.status-badge.todo { background: var(--p-surface-100); }
+.status-badge.progress { background: var(--p-blue-100); color: var(--p-blue-700); }
+.status-badge.done { background: var(--p-green-100); color: var(--p-green-700); }
+.status-badge.cancelled { background: var(--p-red-100); color: var(--p-red-700); }
+.field { margin-bottom: 0.75rem; }
+.field label { display: block; margin-bottom: 0.25rem; font-weight: 500; font-size: 0.875rem; }
+.field-row { display: flex; gap: 0.75rem; }
+.field-row .field { flex: 1; }
+.share-row { display: flex; gap: 0.5rem; align-items: center; flex-wrap: wrap; }
+.rename-row { display: flex; align-items: center; gap: 0.5rem; margin-bottom: 0.75rem; }
+.rename-row strong { font-size: 1rem; }
+.user-search-popup { position: absolute; top: 100%; left: 0; right: 0; z-index: 10;
+                     background: white; border: 1px solid var(--p-surface-200);
+                     border-radius: 4px; max-height: 160px; overflow-y: auto;
+                     box-shadow: 0 4px 12px rgba(0,0,0,0.1); }
+.user-result { padding: 0.5rem 0.75rem; cursor: pointer; font-size: 0.875rem;
+               display: flex; gap: 0.5rem; align-items: center; }
+.user-result:hover { background: var(--p-primary-50); }
+.user-fullname { color: var(--p-text-muted-color); font-size: 0.75rem; margin-left: auto; }
+.existing-shares { margin-top: 0.5rem; }
+.share-perm-item { display: flex; align-items: center; gap: 0.5rem; padding: 0.375rem 0; font-size: 0.875rem; flex-wrap: wrap; }
+.share-perm-item.editing { background: var(--p-surface-50); padding: 0.5rem; border-radius: 4px; }
+.perm-label { color: var(--p-text-muted-color); font-size: 0.75rem; }
+.url-row { display: flex; gap: 0.5rem; align-items: center; flex-wrap: wrap; }
+.url-row strong { min-width: 110px; font-size: 0.8rem; }
+.url-row code { background: var(--p-surface-100); padding: 0.25rem 0.5rem; border-radius: 4px; font-size: 0.8rem; flex: 1; word-break: break-all; }
+.caldav-hint { font-size: 0.8rem; color: var(--p-text-muted-color); margin: 0 0 0.5rem; }
+</style>

nginx.example.conf

@@ -24,15 +24,40 @@ server {
         proxy_set_header Connection "upgrade";
     }
 
-    # CalDAV/CardDAV braucht spezielle Methoden
+    # Server-Sent Events: Puffer aus, lange Read-Timeouts, sonst bricht die
+    # Live-Refresh-Verbindung nach ein paar Sekunden ab.
+    location /api/sync/events {
+        proxy_pass http://127.0.0.1:5000;
+        proxy_set_header Host $host;
+        proxy_set_header X-Real-IP $remote_addr;
+        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+        proxy_set_header X-Forwarded-Proto $scheme;
+
+        proxy_http_version 1.1;
+        proxy_buffering off;
+        proxy_cache off;
+        proxy_read_timeout 24h;
+        proxy_send_timeout 24h;
+        chunked_transfer_encoding on;
+    }
+
+    # CalDAV/CardDAV braucht spezielle Methoden (PROPFIND, REPORT, MKCALENDAR)
     location /dav/ {
+        # Nach 2017 erlaubt nginx die meisten WebDAV-Methoden out of the box.
+        # Wichtig: kein Buffering der Request-Body (PUT groesserer ICS) und
+        # korrekte Forward-Header fuer HTTP-Basic-Auth.
         proxy_pass http://127.0.0.1:5000;
         proxy_set_header Host $host;
         proxy_set_header X-Real-IP $remote_addr;
         proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
         proxy_set_header X-Forwarded-Proto $scheme;
         proxy_pass_request_headers on;
+        proxy_request_buffering off;
+        client_max_body_size 50M;
     }
+
+    location = /.well-known/caldav  { return 301 https://$host/dav/; }
+    location = /.well-known/carddav { return 301 https://$host/dav/; }
 }
 
 # OnlyOffice Document Server (optional)