feat(crm): integrate Lexware Office for vouchers and contact sync

Adds complete Lexware Office integration to CRM service: - Rate-limited HTTP client (Token Bucket, 2 req/s) - Bidirectional contact sync (manual import + ERP-push) - Voucher caching (quotes, orders, invoices, credit notes) - Deal-voucher linking (m:n join table with audit) - Cron jobs: voucher refresh (4h), ERP push (30min) - Distributed locks via Redis for job deduplication - Health check extended with Lexware status - Prisma schema: LexwareVoucher, DealVoucher, VoucherType enum - Companies/Contacts/Deals services extended with Lexware data Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
2026-06-24 23:56:40 +02:00 · 2026-03-10 20:28:41 +01:00 · 2026-03-10 20:28:41 +01:00 · 9d496d2e53
commit 9d496d2e53
parent 411a6bbbcb
31 changed files with 3173 additions and 99 deletions
--- a/docker-compose.crm.yml
+++ b/docker-compose.crm.yml
@ -24,6 +24,9 @@ services:
      - JWT_PUBLIC_KEY_PATH=/app/keys/jwt-public.pem
      - JWT_ISSUER=${JWT_ISSUER:-insight-platform}
      - CORS_ORIGINS=${CORS_ORIGINS:-http://172.20.10.59}
+      # Lexware Office Integration (optional)
+      - LEXWARE_API_KEY=${LEXWARE_API_KEY:-}
+      - LEXWARE_API_URL=${LEXWARE_API_URL:-https://api.lexware.io}
    volumes:
      - ./packages/crm-service:/app
      - /app/node_modules
--- a/docs/INSIGHT-CRM.md
+++ b/docs/INSIGHT-CRM.md
@ -428,4 +428,150 @@ packages/frontend/src/crm/companies/

 ---

+## 2026-03-10 | Backend: Lexware Office Integration
+
+### Ueberblick
+
+Der CRM-Service ist jetzt mit Lexware Office (Buchhaltung/ERP) integriert. Drei Hauptfunktionen:
+
+1. **Kontakt-Verknuepfung**: Lexware-Kontakte suchen und mit CRM Companies/Contacts verknuepfen oder importieren
+2. **Beleg-Anzeige**: Angebote, Auftragsbestaetigungen, Rechnungen und Gutschriften aus Lexware — anzeigbar am Unternehmen, Kontakt UND am Vorgang
+3. **ERP-Push**: CRM-Entitaeten mit Tag "ERP" werden automatisch nach Lexware synchronisiert
+
+### Neue API-Endpoints: Lexware Kontakte
+
+| Methode | Pfad | Beschreibung |
+|---------|------|-------------|
+| GET | `/crm/lexware/contacts/search?name=&email=` | Lexware-Kontakte suchen (Proxy zur Lexware API) |
+| POST | `/crm/lexware/contacts/link-company` | Lexware-Kontakt mit CRM Company verknuepfen |
+| POST | `/crm/lexware/contacts/link-contact` | Lexware-Kontakt mit CRM Contact verknuepfen |
+| DELETE | `/crm/lexware/contacts/unlink-company/:companyId` | Verknuepfung Company <-> Lexware loesen |
+| DELETE | `/crm/lexware/contacts/unlink-contact/:contactId` | Verknuepfung Contact <-> Lexware loesen |
+| POST | `/crm/lexware/contacts/import-company` | Neue CRM Company aus Lexware-Daten erstellen |
+| POST | `/crm/lexware/contacts/import-contact` | Neuen CRM Contact aus Lexware-Daten erstellen |
+| POST | `/crm/lexware/contacts/push/:entityType/:entityId` | CRM-Entitaet nach Lexware pushen (company/contact) |
+| POST | `/crm/lexware/contacts/sync/:entityType/:entityId` | Lexware-Daten in CRM aktualisieren |
+
+### Neue API-Endpoints: Lexware Belege (Vouchers)
+
+| Methode | Pfad | Beschreibung |
+|---------|------|-------------|
+| GET | `/crm/lexware/vouchers/company/:companyId` | Belege fuer Unternehmen (gecacht) |
+| GET | `/crm/lexware/vouchers/contact/:contactId` | Belege fuer Kontakt (gecacht) |
+| GET | `/crm/lexware/vouchers/deal/:dealId` | Belege fuer Vorgang (via DealVoucher) |
+| POST | `/crm/lexware/vouchers/deal/:dealId/link` | Beleg mit Vorgang verknuepfen |
+| DELETE | `/crm/lexware/vouchers/deal/:dealId/unlink/:voucherId` | Beleg-Verknuepfung loesen |
+| POST | `/crm/lexware/vouchers/refresh/company/:companyId` | Beleg-Cache manuell aktualisieren |
+| POST | `/crm/lexware/vouchers/refresh/contact/:contactId` | Beleg-Cache manuell aktualisieren |
+
+### Beleg-Filter Query-Parameter
+
+| Parameter | Typ | Beschreibung |
+|-----------|-----|-------------|
+| `voucherType` | string | `QUOTATION`, `ORDER_CONFIRMATION`, `INVOICE`, `CREDIT_NOTE` |
+| `voucherStatus` | string | Freitext-Filter nach Beleg-Status |
+| `page` | number | Seite (default: 1) |
+| `pageSize` | number | Eintraege pro Seite (default: 20) |
+
+### LexwareVoucher-Objekt
+
+```typescript
+interface LexwareVoucher {
+  id: string;                // CRM-interne UUID
+  voucherType: 'QUOTATION' | 'ORDER_CONFIRMATION' | 'INVOICE' | 'CREDIT_NOTE';
+  voucherNumber?: string;    // z.B. "RE-2025-001"
+  voucherDate?: string;      // ISO DateTime
+  voucherStatus?: string;    // z.B. "open", "paid", "overdue"
+  totalGrossAmount?: string; // Decimal als String, z.B. "1190.00"
+  totalNetAmount?: string;
+  totalTaxAmount?: string;
+  currency: string;          // Default "EUR"
+  title?: string;
+  lineItemsCount?: number;
+  lineItemsJson?: string;    // JSON-String mit Positionen
+  lexwareDeepLink?: string;  // Link direkt zu Lexware Office
+  fetchedAt: string;         // Wann zuletzt aus Lexware geholt
+}
+```
+
+### Aenderungen an bestehenden Responses
+
+**Company-Objekt** hat jetzt zusaetzliche Felder:
+```json
+{
+  "lexwareContactId": "abc-123",       // null wenn nicht verknuepft
+  "lexwareContactVersion": 3,          // Optimistic Locking
+  "lexwareSyncedAt": "2026-03-10...",  // Letzter Sync
+  "_count": { "contacts": 5, "deals": 2, "lexwareVouchers": 12 }
+}
+```
+
+**Contact-Objekt**: Identische neue Felder wie Company.
+
+**Deal-Detail** liefert jetzt zusaetzlich `dealVouchers[]`:
+```json
+{
+  "dealVouchers": [
+    {
+      "id": "...",
+      "linkedAt": "2026-03-10...",
+      "voucher": {
+        "id": "...",
+        "voucherType": "INVOICE",
+        "voucherNumber": "RE-2025-001",
+        "voucherDate": "2025-12-15...",
+        "voucherStatus": "paid",
+        "totalGrossAmount": "1190.00",
+        "currency": "EUR",
+        "title": "Lizenzgebuehr Q4",
+        "lexwareDeepLink": "https://app.lexware.de/permalink/..."
+      }
+    }
+  ]
+}
+```
+
+### Vorschlaege fuer das Frontend
+
+1. **Company/Contact-Detail**: Tab oder Sektion "Lexware" mit:
+   - Status-Badge: "Verknuepft" (gruen) / "Nicht verknuepft" (grau)
+   - Button "Lexware-Kontakt suchen & verknuepfen" → Modal mit Suchfeld
+   - Button "Verknuepfung loesen"
+   - Button "Belege aktualisieren" (Refresh-Icon)
+   - Beleg-Tabelle: Typ, Nummer, Datum, Status, Brutto-Betrag, Link zu Lexware
+
+2. **Deal-Detail**: Sektion "Belege" mit:
+   - Verknuepfte Belege als Tabelle (aus `dealVouchers`)
+   - Button "Beleg verknuepfen" → Dropdown/Modal mit verfuegbaren Belegen des Unternehmens/Kontakts
+   - Jeder Beleg hat einen externen Link zu Lexware Office
+
+3. **Tags-Integration**: "ERP"-Tag in Company/Contact-Formularen hervorheben (z.B. besondere Farbe), da es den automatischen Push nach Lexware aktiviert
+
+4. **VoucherType Labels** fuer die UI:
+   - `QUOTATION` → "Angebot"
+   - `ORDER_CONFIRMATION` → "Auftragsbestaetigung"
+   - `INVOICE` → "Rechnung"
+   - `CREDIT_NOTE` → "Gutschrift"
+
+### Cron-Jobs (automatisch im Hintergrund)
+
+- **Beleg-Sync**: Alle 4 Stunden werden Belege fuer alle verknuepften Entitaeten aus Lexware geholt
+- **ERP-Push**: Alle 30 Minuten werden Companies/Contacts mit "ERP"-Tag nach Lexware gepusht
+
+### Health Check
+
+`GET /health` zeigt jetzt `"lexware": "up"|"down"|"unconfigured"`:
+- `up`: Lexware API erreichbar
+- `down`: API-Key konfiguriert aber API nicht erreichbar
+- `unconfigured`: Kein API-Key gesetzt (kein Fehler, Modul einfach deaktiviert)
+
+### Deployment-Hinweise
+
+- Neue Env-Variable auf Server: `LEXWARE_API_KEY` (in `.env`)
+- DB-Migration noetig: `migration.sql` in `prisma/migrations/20260310_add_lexware_integration/`
+- Neue Tabellen: `lexware_vouchers`, `deal_vouchers`
+- Neue Felder: `lexware_contact_id`, `lexware_contact_version`, `lexware_synced_at` auf `companies` und `contacts`
+
+---
+
 *Bitte neue Eintraege unten anfuegen. Format: `## YYYY-MM-DD | Absender: Betreff`*
--- a/packages/crm-service/Summarize.md
+++ b/packages/crm-service/Summarize.md
@ -10,47 +10,68 @@ Der CRM-Service als eigenstaendiges NestJS-Package unter `packages/crm-service/`

 ```
 packages/crm-service/
-  package.json          — Dependencies (NestJS 10, Prisma, Passport, ioredis)
+  package.json          — Dependencies (NestJS 10, Prisma, Passport, ioredis, @nestjs/axios, @nestjs/schedule)
  tsconfig.json         — Strict TypeScript
  nest-cli.json         — NestJS CLI Config
  Dockerfile            — Multi-Stage (base, deps, development, build, production)
  .dockerignore         — Excludes
  prisma/
    crm.schema.prisma   — Eigenes Schema (app_crm) mit eigenem Client-Output
+    migrations/         — SQL-Migrationen
  src/
    main.ts             — Bootstrap (Port 3100, Prefix: api/v1/crm, Swagger)
-    app.module.ts       — Root Module mit globalem JwtAuthGuard + ExceptionFilter
-    config/             — Umgebungsvariablen-Validierung
+    app.module.ts       — Root Module mit globalem JwtAuthGuard + ExceptionFilter + ScheduleModule
+    config/             — Umgebungsvariablen-Validierung (inkl. LEXWARE_*)
    prisma/             — CrmPrismaService (eigener Client)
-    redis/              — RedisService (Token-Blocklist, Cache)
+    redis/              — RedisService (Token-Blocklist, Cache, Distributed Locks)
    auth/               — JWT Strategy (RS256), JwtAuthGuard, RolesGuard, TenantGuard
    common/             — Decorators (@Public, @Roles, @CurrentUser), Pagination, ExceptionFilter
-    companies/          — CRUD: Unternehmen (uebergeordnete Entity)
-    contacts/           — CRUD: Kontakte (PERSON, ORGANIZATION) mit Company-Verknuepfung
+    companies/          — CRUD: Unternehmen (mit Lexware ERP-Push bei Update)
+    contacts/           — CRUD: Kontakte (mit Lexware ERP-Push bei Update)
    activities/         — CRUD: Aktivitaeten (NOTE, CALL, EMAIL, MEETING, TASK)
    pipelines/          — CRUD: Sales-Pipelines mit Stages (inkl. Stage-Update)
-    deals/              — CRUD: Vorgaenge mit Pipeline/Stage/Contact/Company-Zuordnung
+    deals/              — CRUD: Vorgaenge mit Pipeline/Stage/Contact/Company + DealVouchers
+    health/             — Health-Check (DB, Redis, Lexware)
+    lexware/            — Lexware Office Integration (NEU)
+      lexware.module.ts              — Feature Module (HttpModule + ScheduleModule)
+      lexware-client.service.ts      — Rate-limitierter HTTP Client (Token Bucket, 2 req/s)
+      lexware-contacts.service.ts    — Kontakt-Suche, Link, Import, Push, Sync
+      lexware-vouchers.service.ts    — Beleg-Abruf, Cache, Deal-Verknuepfung
+      lexware-sync.service.ts        — Cron-Jobs (Beleg-Sync 4h, ERP-Push 30min)
+      lexware-contacts.controller.ts — REST Endpoints Kontakt-Operationen
+      lexware-vouchers.controller.ts — REST Endpoints Beleg-Operationen
+      dto/                           — Validierungs-DTOs
+      interfaces/                    — TypeScript Interfaces fuer Lexware API
+      utils/
+        rate-limiter.ts              — Token Bucket (max 2, 2/s Refill)
+        lexware-mapper.ts            — Bidirektionales Mapping CRM <-> Lexware
 ```

 ### Datenbank-Modelle (app_crm Schema)

- **Company** — Unternehmen mit Branche, Adresse, Tags, Audit-Trail. Eltern-Entity fuer Contacts und Deals.
- **Contact** — Kontakte (Person/Organisation) mit optionaler Company-Zuordnung (companyId, position)
+- **Company** — Unternehmen mit Lexware-Verknuepfung (lexwareContactId, lexwareContactVersion, lexwareSyncedAt)
+- **Contact** — Kontakte mit optionaler Lexware-Verknuepfung
 - **Activity** — Aktivitaeten verknuepft mit Kontakten
 - **Pipeline** — Konfigurierbare Sales-Pipelines pro Tenant
- **PipelineStage** — Stufen innerhalb einer Pipeline (Name, Farbe, Reihenfolge editierbar)
- **Deal** — Vorgaenge mit Wert, Status, Pipeline/Stage/Contact/Company-Zuordnung
+- **PipelineStage** — Stufen innerhalb einer Pipeline
+- **Deal** — Vorgaenge mit dealVouchers-Relation zu Lexware-Belegen
+- **LexwareVoucher** (NEU) — Gecachte Belege aus Lexware Office (Angebote, Auftraege, Rechnungen, Gutschriften)
+- **DealVoucher** (NEU) — Join-Table Deal <-> Beleg (m:n mit Audit-Trail)

 ### Entity-Beziehungen

 ```
-Company (1) --< (n) Contact     — companyId (optional, SetNull bei Loeschung)
-Company (1) --< (n) Deal        — companyId (optional, SetNull bei Loeschung)
-Contact (1) --< (n) Activity    — contactId (Cascade bei Loeschung)
-Contact (1) --< (n) Deal        — contactId (optional, SetNull bei Loeschung)
-Pipeline (1) --< (n) PipelineStage — pipelineId (Cascade bei Loeschung)
-Pipeline (1) --< (n) Deal       — pipelineId (Cascade bei Loeschung)
-PipelineStage (1) --< (n) Deal  — stageId
+Company (1) --< (n) Contact          — companyId (optional, SetNull)
+Company (1) --< (n) Deal             — companyId (optional, SetNull)
+Company (1) --< (n) LexwareVoucher   — companyId (optional, SetNull)
+Contact (1) --< (n) Activity         — contactId (Cascade)
+Contact (1) --< (n) Deal             — contactId (optional, SetNull)
+Contact (1) --< (n) LexwareVoucher   — contactId (optional, SetNull)
+Pipeline (1) --< (n) PipelineStage   — pipelineId (Cascade)
+Pipeline (1) --< (n) Deal            — pipelineId (Cascade)
+PipelineStage (1) --< (n) Deal       — stageId
+Deal (1) --< (n) DealVoucher         — dealId (Cascade)
+LexwareVoucher (1) --< (n) DealVoucher — voucherId (Cascade)
 ```

 ### API-Endpunkte
@ -66,73 +87,68 @@ PipelineStage (1) --< (n) Deal  — stageId
 | GET/POST | /api/v1/crm/pipelines | Liste / Erstellen |
 | GET/PATCH/DELETE | /api/v1/crm/pipelines/:id | Detail / Update / Delete |
 | POST/DELETE | /api/v1/crm/pipelines/:id/stages | Stage hinzufuegen/entfernen |
-| PATCH | /api/v1/crm/pipelines/:id/stages/:stageId | Stage bearbeiten (Name, Farbe, Reihenfolge) |
+| PATCH | /api/v1/crm/pipelines/:id/stages/:stageId | Stage bearbeiten |
 | GET/POST | /api/v1/crm/deals | Liste / Erstellen |
 | GET/PATCH/DELETE | /api/v1/crm/deals/:id | Detail / Update / Delete |
-| GET | /health | Health-Check (public) |
+| GET | /health | Health-Check (DB, Redis, Lexware) |
+| **Lexware Kontakte** | | |
+| GET | /api/v1/crm/lexware/contacts/search | Lexware-Kontakte suchen |
+| POST | /api/v1/crm/lexware/contacts/link-company | Company verknuepfen |
+| POST | /api/v1/crm/lexware/contacts/link-contact | Contact verknuepfen |
+| DELETE | /api/v1/crm/lexware/contacts/unlink-company/:id | Verknuepfung loesen |
+| DELETE | /api/v1/crm/lexware/contacts/unlink-contact/:id | Verknuepfung loesen |
+| POST | /api/v1/crm/lexware/contacts/import-company | Company aus Lexware importieren |
+| POST | /api/v1/crm/lexware/contacts/import-contact | Contact aus Lexware importieren |
+| POST | /api/v1/crm/lexware/contacts/push/:type/:id | CRM -> Lexware pushen |
+| POST | /api/v1/crm/lexware/contacts/sync/:type/:id | Lexware -> CRM synchronisieren |
+| **Lexware Belege** | | |
+| GET | /api/v1/crm/lexware/vouchers/company/:id | Belege fuer Unternehmen |
+| GET | /api/v1/crm/lexware/vouchers/contact/:id | Belege fuer Kontakt |
+| GET | /api/v1/crm/lexware/vouchers/deal/:id | Belege fuer Vorgang |
+| POST | /api/v1/crm/lexware/vouchers/deal/:id/link | Beleg mit Vorgang verknuepfen |
+| DELETE | /api/v1/crm/lexware/vouchers/deal/:id/unlink/:vid | Verknuepfung loesen |
+| POST | /api/v1/crm/lexware/vouchers/refresh/company/:id | Cache aktualisieren |
+| POST | /api/v1/crm/lexware/vouchers/refresh/contact/:id | Cache aktualisieren |
+
+### Lexware Office Integration — Details
+
+- **Rate Limiter**: In-Memory Token Bucket, 2 Requests/Sekunde (Lexware API Limit)
+- **Beleg-Caching**: PostgreSQL-Tabelle `lexware_vouchers`, alle 4h Cron-Refresh + manueller Refresh
+- **ERP-Push**: Companies/Contacts mit Tag "ERP" werden automatisch (30min Cron) + bei Update nach Lexware gepusht
+- **Distributed Locks**: Redis SET NX EX verhindert Doppelausfuehrung von Cron-Jobs
+- **Optimistic Locking**: lexwareContactVersion fuer sichere Updates
+- **Graceful Degradation**: Ohne LEXWARE_API_KEY → Modul deaktiviert, Health = "unconfigured"

 ### Docker-Integration

 - `docker-compose.crm.yml` im Projekt-Root
 - Port: 3100
- Netzwerke: insight-web, insight-db, insight-cache
- Traefik HTTP-Route: `Host(172.20.10.59) && PathPrefix(/api/v1/crm)` mit Priority 100
- Traefik HTTPS-Route: `crm-secure` mit `entrypoints=websecure`, `tls=true`, Priority 100
- JWT Public Key als Read-Only Volume (.keys/jwt-public.pem)
- Direkte PostgreSQL-Verbindung (PgBouncer unterstuetzt kein search_path fuer Schema-Auswahl)
+- Neue Env-Variablen: `LEXWARE_API_KEY`, `LEXWARE_API_URL`
+- Traefik HTTP + HTTPS Routing: `/api/v1/crm/*`

 ### Sicherheit

 - JWT RS256 Validierung mit shared Public Key
- Token-Revocation via Redis (blocked:{jti})
+- Token-Revocation via Redis
 - Multi-Tenancy: Alle Queries filtern nach tenantId
- TenantGuard sichert mandantenbezogenen Zugriff
 - Globaler ValidationPipe (whitelist + forbidNonWhitelisted)
 - Strict TypeScript, kein `any`
- 401 bei fehlendem/ungueltigem Token

 ### Deployment-Status

 **Erfolgreich deployed auf insight-dev-01 (172.20.10.59) am 2026-03-10**

- Container: insight-crm (Development-Mode)
- Prisma Migrationen angewendet:
-  - `20260310163211_init` — Initiales Schema (Contact, Activity, Pipeline, PipelineStage, Deal)
-  - `20260310183117_add_companies` — Company-Entity, Contact.companyId/position, Deal.companyId
- Alle API-Endpunkte getestet und funktionsfaehig
- Traefik-Routing aktiv (HTTP + HTTPS): http(s)://172.20.10.59/api/v1/crm/*
- Swagger-Docs: http://172.20.10.59/api/v1/crm/docs/
-
-### Getestete Endpunkte
-
-| Test | Ergebnis |
-|------|----------|
-| POST /companies (Erstellen mit allen Feldern) | 200 OK, UUID + _count korrekt |
-| GET /companies (Liste) | 200 OK, pagination + _count korrekt |
-| GET /companies/:id (Detail) | 200 OK, contacts[] + deals[] + _count |
-| PATCH /companies/:id (Update) | 200 OK, updatedBy + tags korrekt |
-| GET /companies?search=Xinion | 200 OK, Suche funktioniert |
-| POST /contacts (mit companyId + position) | 201 Created, Company-Verknuepfung korrekt |
-| GET /contacts/:id (mit Company) | 200 OK, company-Objekt enthalten |
-| POST /activities (Notiz) | 201 Created, contactId verknuepft |
-| POST /pipelines (mit 4 Stages) | 201 Created, Stages korrekt |
-| PATCH /pipelines/:id/stages/:stageId | 200 OK, Stage-Update korrekt |
-| POST /deals (mit companyId + contactId) | 200 OK, Company + Contact verknuepft |
-| GET /deals/:id (mit Company) | 200 OK, company + pipeline.stages enthalten |
-| GET /deals?companyId=... | 200 OK, Filter nach Company funktioniert |
-| PATCH /deals/:id (WON) | 200 OK, closedAt automatisch gesetzt |
-| GET /contacts ohne Token | 401 Unauthorized |
-| Validierung (falsche Felder) | 400 Bad Request, Details korrekt |
-
-### Bekannte Einschraenkungen
-
- PgBouncer kann nicht genutzt werden (search_path nicht kompatibel mit transaction pooling)
+- Prisma Migrationen:
+  - `20260310163211_init` — Initiales Schema
+  - `20260310183117_add_companies` — Company-Entity
+  - `20260310_add_lexware_integration` — Lexware Office Integration (AUSSTEHEND)

 ### Naechste Schritte

-1. Frontend: Company-Modul (Seiten, Formulare, Sidebar-Link)
-2. Frontend: Contact/Deal-Formulare um Company-Selektor erweitern
-3. Activity-Liste komplett laden (UI-Button "Alle anzeigen")
-4. Kanban-Board fuer Vorgaenge (Drag & Drop Stage-Wechsel)
-5. E2E-Tests schreiben
-6. Production-Build testen (multi-stage Dockerfile)
+1. Migration `20260310_add_lexware_integration` auf Server anwenden
+2. `LEXWARE_API_KEY` in `.env` auf Server setzen
+3. Container neu bauen und deployen
+4. Lexware-Endpunkte auf Server testen
+5. Frontend: Lexware-Integration in Company/Contact/Deal-Detail-Seiten
+6. Activity-Liste komplett laden (UI-Button "Alle anzeigen")
+7. Kanban-Board fuer Vorgaenge
--- a/packages/crm-service/package-lock.json
+++ b/packages/crm-service/package-lock.json
@ -9,13 +9,16 @@
      "version": "0.1.0",
      "license": "UNLICENSED",
      "dependencies": {
+        "@nestjs/axios": "^3.1.3",
        "@nestjs/common": "^10.4.0",
        "@nestjs/config": "^3.2.0",
        "@nestjs/core": "^10.4.0",
        "@nestjs/passport": "^10.0.3",
        "@nestjs/platform-express": "^10.4.0",
+        "@nestjs/schedule": "^4.1.2",
        "@nestjs/swagger": "^7.4.0",
        "@prisma/client": "^6.4.0",
+        "axios": "^1.13.6",
        "class-transformer": "^0.5.1",
        "class-validator": "^0.14.1",
        "cookie-parser": "^1.4.7",
@ -244,6 +247,7 @@
      "integrity": "sha512-CGOfOJqWjg2qW/Mb6zNsDm+u5vFQ8DxXfbM09z69p5Z6+mE1ikP2jUXw+j42Pf1XTYED2Rni5f95npYeuwMDQA==",
      "dev": true,
      "license": "MIT",
+      "peer": true,
      "dependencies": {
        "@babel/code-frame": "^7.29.0",
        "@babel/generator": "^7.29.0",
@ -1726,6 +1730,17 @@
      "integrity": "sha512-4aErSrCR/On/e5G2hDP0wjooqDdauzEbIq8hIkIe5pXV0rtWJZvdCEKL0ykZxex+IxIwBp0eGeV48hQN07dXtw==",
      "license": "MIT"
    },
+    "node_modules/@nestjs/axios": {
+      "version": "3.1.3",
+      "resolved": "https://registry.npmjs.org/@nestjs/axios/-/axios-3.1.3.tgz",
+      "integrity": "sha512-RZ/63c1tMxGLqyG3iOCVt7A72oy4x1eM6QEhd4KzCYpaVWW0igq0WSREeRoEZhIxRcZfDfIIkvsOMiM7yfVGZQ==",
+      "license": "MIT",
+      "peerDependencies": {
+        "@nestjs/common": "^7.0.0 || ^8.0.0 || ^9.0.0 || ^10.0.0",
+        "axios": "^1.3.1",
+        "rxjs": "^6.0.0 || ^7.0.0"
+      }
+    },
    "node_modules/@nestjs/cli": {
      "version": "10.4.9",
      "resolved": "https://registry.npmjs.org/@nestjs/cli/-/cli-10.4.9.tgz",
@ -2001,6 +2016,33 @@
        "@nestjs/core": "^10.0.0"
      }
    },
+    "node_modules/@nestjs/schedule": {
+      "version": "4.1.2",
+      "resolved": "https://registry.npmjs.org/@nestjs/schedule/-/schedule-4.1.2.tgz",
+      "integrity": "sha512-hCTQ1lNjIA5EHxeu8VvQu2Ed2DBLS1GSC6uKPYlBiQe6LL9a7zfE9iVSK+zuK8E2odsApteEBmfAQchc8Hx0Gg==",
+      "license": "MIT",
+      "dependencies": {
+        "cron": "3.2.1",
+        "uuid": "11.0.3"
+      },
+      "peerDependencies": {
+        "@nestjs/common": "^8.0.0 || ^9.0.0 || ^10.0.0",
+        "@nestjs/core": "^8.0.0 || ^9.0.0 || ^10.0.0"
+      }
+    },
+    "node_modules/@nestjs/schedule/node_modules/uuid": {
+      "version": "11.0.3",
+      "resolved": "https://registry.npmjs.org/uuid/-/uuid-11.0.3.tgz",
+      "integrity": "sha512-d0z310fCWv5dJwnX1Y/MncBAqGMKEzlBb1AOf7z9K8ALnd0utBX/msg/fA0+sbyN1ihbMsLhrBlnl1ak7Wa0rg==",
+      "funding": [
+        "https://github.com/sponsors/broofa",
+        "https://github.com/sponsors/ctavan"
+      ],
+      "license": "MIT",
+      "bin": {
+        "uuid": "dist/esm/bin/uuid"
+      }
+    },
    "node_modules/@nestjs/schematics": {
      "version": "10.2.3",
      "resolved": "https://registry.npmjs.org/@nestjs/schematics/-/schematics-10.2.3.tgz",
@ -2504,6 +2546,12 @@
        "@types/node": "*"
      }
    },
+    "node_modules/@types/luxon": {
+      "version": "3.4.2",
+      "resolved": "https://registry.npmjs.org/@types/luxon/-/luxon-3.4.2.tgz",
+      "integrity": "sha512-TifLZlFudklWlMBfhubvgqTXRzLDI5pCbGa4P8a3wPyUQSW+1xQ5eDsreP9DWHX3tjq1ke96uYG/nwundroWcA==",
+      "license": "MIT"
+    },
    "node_modules/@types/ms": {
      "version": "2.1.0",
      "resolved": "https://registry.npmjs.org/@types/ms/-/ms-2.1.0.tgz",
@ -3257,6 +3305,24 @@
      "dev": true,
      "license": "MIT"
    },
+    "node_modules/asynckit": {
+      "version": "0.4.0",
+      "resolved": "https://registry.npmjs.org/asynckit/-/asynckit-0.4.0.tgz",
+      "integrity": "sha512-Oei9OH4tRh0YqU3GxhX79dM/mwVgvbZJaSNaRk+bshkj0S5cfHcgYakreBjrHwatXKbz+IoIdYLxrKim2MjW0Q==",
+      "license": "MIT"
+    },
+    "node_modules/axios": {
+      "version": "1.13.6",
+      "resolved": "https://registry.npmjs.org/axios/-/axios-1.13.6.tgz",
+      "integrity": "sha512-ChTCHMouEe2kn713WHbQGcuYrr6fXTBiu460OTwWrWob16g1bXn4vtz07Ope7ewMozJAnEquLk5lWQWtBig9DQ==",
+      "license": "MIT",
+      "peer": true,
+      "dependencies": {
+        "follow-redirects": "^1.15.11",
+        "form-data": "^4.0.5",
+        "proxy-from-env": "^1.1.0"
+      }
+    },
    "node_modules/babel-jest": {
      "version": "29.7.0",
      "resolved": "https://registry.npmjs.org/babel-jest/-/babel-jest-29.7.0.tgz",
@ -4063,6 +4129,18 @@
      "integrity": "sha512-dOy+3AuW3a2wNbZHIuMZpTcgjGuLU/uBL/ubcZF9OXbDo8ff4O8yVp5Bf0efS8uEoYo5q4Fx7dY9OgQGXgAsQA==",
      "license": "MIT"
    },
+    "node_modules/combined-stream": {
+      "version": "1.0.8",
+      "resolved": "https://registry.npmjs.org/combined-stream/-/combined-stream-1.0.8.tgz",
+      "integrity": "sha512-FQN4MRfuJeHf7cBbBMJFXhKSDq+2kAArBlmRBvcvFE5BB1HZKXtSFASDhdlz9zOYwxh8lDdnvmMOe/+5cdoEdg==",
+      "license": "MIT",
+      "dependencies": {
+        "delayed-stream": "~1.0.0"
+      },
+      "engines": {
+        "node": ">= 0.8"
+      }
+    },
    "node_modules/commander": {
      "version": "4.1.1",
      "resolved": "https://registry.npmjs.org/commander/-/commander-4.1.1.tgz",
@ -4257,6 +4335,16 @@
      "dev": true,
      "license": "MIT"
    },
+    "node_modules/cron": {
+      "version": "3.2.1",
+      "resolved": "https://registry.npmjs.org/cron/-/cron-3.2.1.tgz",
+      "integrity": "sha512-w2n5l49GMmmkBFEsH9FIDhjZ1n1QgTMOCMGuQtOXs5veNiosZmso6bQGuqOJSYAXXrG84WQFVneNk+Yt0Ua9iw==",
+      "license": "MIT",
+      "dependencies": {
+        "@types/luxon": "~3.4.0",
+        "luxon": "~3.5.0"
+      }
+    },
    "node_modules/cross-spawn": {
      "version": "7.0.6",
      "resolved": "https://registry.npmjs.org/cross-spawn/-/cross-spawn-7.0.6.tgz",
@ -4369,6 +4457,15 @@
      "devOptional": true,
      "license": "MIT"
    },
+    "node_modules/delayed-stream": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/delayed-stream/-/delayed-stream-1.0.0.tgz",
+      "integrity": "sha512-ZySD7Nf91aLB0RxL4KGrKHBXl7Eds1DAmEdcoVawXnLD7SDhpNgtuII2aAkg7a7QS41jxPSZ17p4VdGnMHk3MQ==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=0.4.0"
+      }
+    },
    "node_modules/denque": {
      "version": "2.1.0",
      "resolved": "https://registry.npmjs.org/denque/-/denque-2.1.0.tgz",
@ -4609,6 +4706,21 @@
        "node": ">= 0.4"
      }
    },
+    "node_modules/es-set-tostringtag": {
+      "version": "2.1.0",
+      "resolved": "https://registry.npmjs.org/es-set-tostringtag/-/es-set-tostringtag-2.1.0.tgz",
+      "integrity": "sha512-j6vWzfrGVfyXxge+O0x5sh6cvxAog0a/4Rdd2K36zCMV5eJ+/+tOAngRO8cODMNWbVRdVlmGZQL2YS3yR8bIUA==",
+      "license": "MIT",
+      "dependencies": {
+        "es-errors": "^1.3.0",
+        "get-intrinsic": "^1.2.6",
+        "has-tostringtag": "^1.0.2",
+        "hasown": "^2.0.2"
+      },
+      "engines": {
+        "node": ">= 0.4"
+      }
+    },
    "node_modules/escalade": {
      "version": "3.2.0",
      "resolved": "https://registry.npmjs.org/escalade/-/escalade-3.2.0.tgz",
@ -5353,6 +5465,26 @@
      "dev": true,
      "license": "ISC"
    },
+    "node_modules/follow-redirects": {
+      "version": "1.15.11",
+      "resolved": "https://registry.npmjs.org/follow-redirects/-/follow-redirects-1.15.11.tgz",
+      "integrity": "sha512-deG2P0JfjrTxl50XGCDyfI97ZGVCxIpfKYmfyrQ54n5FO/0gfIES8C/Psl6kWVDolizcaaxZJnTS0QSMxvnsBQ==",
+      "funding": [
+        {
+          "type": "individual",
+          "url": "https://github.com/sponsors/RubenVerborgh"
+        }
+      ],
+      "license": "MIT",
+      "engines": {
+        "node": ">=4.0"
+      },
+      "peerDependenciesMeta": {
+        "debug": {
+          "optional": true
+        }
+      }
+    },
    "node_modules/foreground-child": {
      "version": "3.3.1",
      "resolved": "https://registry.npmjs.org/foreground-child/-/foreground-child-3.3.1.tgz",
@ -5430,6 +5562,22 @@
        "node": "*"
      }
    },
+    "node_modules/form-data": {
+      "version": "4.0.5",
+      "resolved": "https://registry.npmjs.org/form-data/-/form-data-4.0.5.tgz",
+      "integrity": "sha512-8RipRLol37bNs2bhoV67fiTEvdTrbMUYcFTiy3+wuuOnUog2QBHCZWXDRijWQfAkhBj2Uf5UnVaiWwA5vdd82w==",
+      "license": "MIT",
+      "dependencies": {
+        "asynckit": "^0.4.0",
+        "combined-stream": "^1.0.8",
+        "es-set-tostringtag": "^2.1.0",
+        "hasown": "^2.0.2",
+        "mime-types": "^2.1.12"
+      },
+      "engines": {
+        "node": ">= 6"
+      }
+    },
    "node_modules/forwarded": {
      "version": "0.2.0",
      "resolved": "https://registry.npmjs.org/forwarded/-/forwarded-0.2.0.tgz",
@ -5792,6 +5940,21 @@
        "url": "https://github.com/sponsors/ljharb"
      }
    },
+    "node_modules/has-tostringtag": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/has-tostringtag/-/has-tostringtag-1.0.2.tgz",
+      "integrity": "sha512-NqADB8VjPFLM2V0VvHUewwwsw0ZWBaIdgo+ieHtK3hasLz4qeCRjYcqfB6AQrBggRKppKF8L52/VqdVsO47Dlw==",
+      "license": "MIT",
+      "dependencies": {
+        "has-symbols": "^1.0.3"
+      },
+      "engines": {
+        "node": ">= 0.4"
+      },
+      "funding": {
+        "url": "https://github.com/sponsors/ljharb"
+      }
+    },
    "node_modules/hasown": {
      "version": "2.0.2",
      "resolved": "https://registry.npmjs.org/hasown/-/hasown-2.0.2.tgz",
@ -7314,6 +7477,15 @@
        "yallist": "^3.0.2"
      }
    },
+    "node_modules/luxon": {
+      "version": "3.5.0",
+      "resolved": "https://registry.npmjs.org/luxon/-/luxon-3.5.0.tgz",
+      "integrity": "sha512-rh+Zjr6DNfUYR3bPwJEnuwDdqMbxZW7LOQfUN4B54+Cl+0o5zaU9RJ6bcidfDtC1cWCZXQ+nvX8bf6bAji37QQ==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=12"
+      }
+    },
    "node_modules/magic-string": {
      "version": "0.30.8",
      "resolved": "https://registry.npmjs.org/magic-string/-/magic-string-0.30.8.tgz",
@ -8277,6 +8449,12 @@
        "node": ">= 0.10"
      }
    },
+    "node_modules/proxy-from-env": {
+      "version": "1.1.0",
+      "resolved": "https://registry.npmjs.org/proxy-from-env/-/proxy-from-env-1.1.0.tgz",
+      "integrity": "sha512-D+zkORCbA9f1tdWRK0RaCR3GPv50cMxcrz4X8k5LTSUD1Dkw47mKJEZQNunItRTkWwgtaUSo1RVFRIG9ZXiFYg==",
+      "license": "MIT"
+    },
    "node_modules/punycode": {
      "version": "2.3.1",
      "resolved": "https://registry.npmjs.org/punycode/-/punycode-2.3.1.tgz",
--- a/packages/crm-service/package.json
+++ b/packages/crm-service/package.json
@ -25,13 +25,16 @@
    "prisma:studio": "prisma studio --schema=prisma/crm.schema.prisma"
  },
  "dependencies": {
+    "@nestjs/axios": "^3.1.3",
    "@nestjs/common": "^10.4.0",
    "@nestjs/config": "^3.2.0",
    "@nestjs/core": "^10.4.0",
    "@nestjs/passport": "^10.0.3",
    "@nestjs/platform-express": "^10.4.0",
+    "@nestjs/schedule": "^4.1.2",
    "@nestjs/swagger": "^7.4.0",
    "@prisma/client": "^6.4.0",
+    "axios": "^1.13.6",
    "class-transformer": "^0.5.1",
    "class-validator": "^0.14.1",
    "cookie-parser": "^1.4.7",
@ -69,13 +72,19 @@
    "typescript": "^5.6.0"
  },
  "jest": {
-    "moduleFileExtensions": ["js", "json", "ts"],
+    "moduleFileExtensions": [
+      "js",
+      "json",
+      "ts"
+    ],
    "rootDir": "src",
    "testRegex": ".*\\.spec\\.ts$",
    "transform": {
      "^.+\\.(t|j)s$": "ts-jest"
    },
-    "collectCoverageFrom": ["**/*.(t|j)s"],
+    "collectCoverageFrom": [
+      "**/*.(t|j)s"
+    ],
    "coverageDirectory": "../coverage",
    "testEnvironment": "node",
    "moduleNameMapper": {
--- a/packages/crm-service/prisma/crm.schema.prisma
+++ b/packages/crm-service/prisma/crm.schema.prisma
@ -45,6 +45,11 @@ model Company {

  isActive Boolean @default(true) @map("is_active")

+  // Lexware Office Integration
+  lexwareContactId      String?   @map("lexware_contact_id") @db.VarChar(36)
+  lexwareContactVersion Int?      @map("lexware_contact_version")
+  lexwareSyncedAt       DateTime? @map("lexware_synced_at")
+
  // Audit-Trail
  createdBy String  @map("created_by") @db.Uuid
  updatedBy String? @map("updated_by") @db.Uuid
@ -53,9 +58,11 @@ model Company {
  updatedAt DateTime @updatedAt @map("updated_at")

  // Relationen
-  contacts Contact[]
-  deals    Deal[]
+  contacts        Contact[]
+  deals           Deal[]
+  lexwareVouchers LexwareVoucher[]

+  @@unique([tenantId, lexwareContactId])
  @@index([tenantId])
  @@index([tenantId, name])
  @@index([tenantId, industry])
@ -100,6 +107,11 @@ model Contact {

  isActive Boolean @default(true) @map("is_active")

+  // Lexware Office Integration
+  lexwareContactId      String?   @map("lexware_contact_id") @db.VarChar(36)
+  lexwareContactVersion Int?      @map("lexware_contact_version")
+  lexwareSyncedAt       DateTime? @map("lexware_synced_at")
+
  // Audit-Trail (User-IDs aus platform_core)
  createdBy String  @map("created_by") @db.Uuid
  updatedBy String? @map("updated_by") @db.Uuid
@ -108,10 +120,12 @@ model Contact {
  updatedAt DateTime @updatedAt @map("updated_at")

  // Relationen
-  company    Company?   @relation(fields: [companyId], references: [id], onDelete: SetNull)
-  activities Activity[]
-  deals      Deal[]
+  company         Company?   @relation(fields: [companyId], references: [id], onDelete: SetNull)
+  activities      Activity[]
+  deals           Deal[]
+  lexwareVouchers LexwareVoucher[]

+  @@unique([tenantId, lexwareContactId])
  @@index([tenantId])
  @@index([tenantId, email])
  @@index([tenantId, companyId])
@ -250,10 +264,11 @@ model Deal {
  updatedAt DateTime @updatedAt @map("updated_at")

  // Relationen
-  pipeline Pipeline       @relation(fields: [pipelineId], references: [id], onDelete: Cascade)
-  stage    PipelineStage   @relation(fields: [stageId], references: [id])
-  contact  Contact?        @relation(fields: [contactId], references: [id], onDelete: SetNull)
-  company  Company?        @relation(fields: [companyId], references: [id], onDelete: SetNull)
+  pipeline     Pipeline       @relation(fields: [pipelineId], references: [id], onDelete: Cascade)
+  stage        PipelineStage  @relation(fields: [stageId], references: [id])
+  contact      Contact?       @relation(fields: [contactId], references: [id], onDelete: SetNull)
+  company      Company?       @relation(fields: [companyId], references: [id], onDelete: SetNull)
+  dealVouchers DealVoucher[]

  @@index([tenantId])
  @@index([tenantId, pipelineId])
@ -272,3 +287,86 @@ enum DealStatus {

  @@schema("app_crm")
 }
+
+// --------------------------------------------------------
+// Lexware Office Integration - Voucher Types
+// --------------------------------------------------------
+enum VoucherType {
+  QUOTATION
+  ORDER_CONFIRMATION
+  INVOICE
+  CREDIT_NOTE
+
+  @@schema("app_crm")
+}
+
+// --------------------------------------------------------
+// LexwareVoucher - Gecachte Belege aus Lexware Office
+// --------------------------------------------------------
+model LexwareVoucher {
+  id               String      @id @default(uuid()) @db.Uuid
+  tenantId         String      @map("tenant_id") @db.Uuid
+  lexwareVoucherId String      @map("lexware_voucher_id") @db.VarChar(36)
+  voucherType      VoucherType @map("voucher_type")
+
+  voucherNumber  String?  @map("voucher_number") @db.VarChar(100)
+  voucherDate    DateTime? @map("voucher_date")
+  voucherStatus  String?  @map("voucher_status") @db.VarChar(50)
+
+  totalGrossAmount Decimal? @map("total_gross_amount") @db.Decimal(15, 2)
+  totalNetAmount   Decimal? @map("total_net_amount") @db.Decimal(15, 2)
+  totalTaxAmount   Decimal? @map("total_tax_amount") @db.Decimal(15, 2)
+  currency         String   @default("EUR") @db.VarChar(3)
+
+  title          String? @db.VarChar(500)
+  lineItemsCount Int?    @map("line_items_count")
+  lineItemsJson  String? @map("line_items_json") @db.Text
+
+  // Verknuepfung zu Lexware-Kontakt und CRM-Entitaeten
+  lexwareContactId String  @map("lexware_contact_id") @db.VarChar(36)
+  companyId        String? @map("company_id") @db.Uuid
+  contactId        String? @map("contact_id") @db.Uuid
+
+  lexwareDeepLink String? @map("lexware_deep_link") @db.VarChar(500)
+
+  fetchedAt DateTime @default(now()) @map("fetched_at")
+  createdAt DateTime @default(now()) @map("created_at")
+  updatedAt DateTime @updatedAt @map("updated_at")
+
+  // Relationen
+  company Company? @relation(fields: [companyId], references: [id], onDelete: SetNull)
+  contact Contact? @relation(fields: [contactId], references: [id], onDelete: SetNull)
+  deals   DealVoucher[]
+
+  @@unique([tenantId, lexwareVoucherId])
+  @@index([tenantId])
+  @@index([tenantId, companyId])
+  @@index([tenantId, contactId])
+  @@index([tenantId, lexwareContactId])
+  @@index([tenantId, voucherType])
+  @@map("lexware_vouchers")
+  @@schema("app_crm")
+}
+
+// --------------------------------------------------------
+// DealVoucher - Verknuepfung Deal <-> Lexware-Beleg (m:n)
+// --------------------------------------------------------
+model DealVoucher {
+  id        String   @id @default(uuid()) @db.Uuid
+  tenantId  String   @map("tenant_id") @db.Uuid
+  dealId    String   @map("deal_id") @db.Uuid
+  voucherId String   @map("voucher_id") @db.Uuid
+  linkedBy  String   @map("linked_by") @db.Uuid
+  linkedAt  DateTime @default(now()) @map("linked_at")
+
+  // Relationen
+  deal    Deal           @relation(fields: [dealId], references: [id], onDelete: Cascade)
+  voucher LexwareVoucher @relation(fields: [voucherId], references: [id], onDelete: Cascade)
+
+  @@unique([dealId, voucherId])
+  @@index([tenantId])
+  @@index([tenantId, dealId])
+  @@index([tenantId, voucherId])
+  @@map("deal_vouchers")
+  @@schema("app_crm")
+}
--- a/packages/crm-service/prisma/migrations/20260310_add_lexware_integration/migration.sql
+++ b/packages/crm-service/prisma/migrations/20260310_add_lexware_integration/migration.sql
@ -0,0 +1,118 @@
+-- ============================================================
+-- Lexware Office Integration - Schema Migration
+-- ============================================================
+-- Neue Felder auf Company, Contact
+-- Neue Tabellen: lexware_vouchers, deal_vouchers
+-- Neuer Enum: VoucherType
+-- ============================================================
+
+-- VoucherType Enum
+CREATE TYPE "app_crm"."VoucherType" AS ENUM ('QUOTATION', 'ORDER_CONFIRMATION', 'INVOICE', 'CREDIT_NOTE');
+
+-- Company: Lexware-Felder hinzufuegen
+ALTER TABLE "app_crm"."companies"
+  ADD COLUMN "lexware_contact_id" VARCHAR(36),
+  ADD COLUMN "lexware_contact_version" INTEGER,
+  ADD COLUMN "lexware_synced_at" TIMESTAMP(3);
+
+-- Contact: Lexware-Felder hinzufuegen
+ALTER TABLE "app_crm"."contacts"
+  ADD COLUMN "lexware_contact_id" VARCHAR(36),
+  ADD COLUMN "lexware_contact_version" INTEGER,
+  ADD COLUMN "lexware_synced_at" TIMESTAMP(3);
+
+-- Unique Constraints (tenantId + lexwareContactId)
+CREATE UNIQUE INDEX "companies_tenant_id_lexware_contact_id_key"
+  ON "app_crm"."companies"("tenant_id", "lexware_contact_id");
+
+CREATE UNIQUE INDEX "contacts_tenant_id_lexware_contact_id_key"
+  ON "app_crm"."contacts"("tenant_id", "lexware_contact_id");
+
+-- LexwareVoucher Tabelle
+CREATE TABLE "app_crm"."lexware_vouchers" (
+  "id" UUID NOT NULL DEFAULT gen_random_uuid(),
+  "tenant_id" UUID NOT NULL,
+  "lexware_voucher_id" VARCHAR(36) NOT NULL,
+  "voucher_type" "app_crm"."VoucherType" NOT NULL,
+  "voucher_number" VARCHAR(100),
+  "voucher_date" TIMESTAMP(3),
+  "voucher_status" VARCHAR(50),
+  "total_gross_amount" DECIMAL(15,2),
+  "total_net_amount" DECIMAL(15,2),
+  "total_tax_amount" DECIMAL(15,2),
+  "currency" VARCHAR(3) NOT NULL DEFAULT 'EUR',
+  "title" VARCHAR(500),
+  "line_items_count" INTEGER,
+  "line_items_json" TEXT,
+  "lexware_contact_id" VARCHAR(36) NOT NULL,
+  "company_id" UUID,
+  "contact_id" UUID,
+  "lexware_deep_link" VARCHAR(500),
+  "fetched_at" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+  "created_at" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+  "updated_at" TIMESTAMP(3) NOT NULL,
+
+  CONSTRAINT "lexware_vouchers_pkey" PRIMARY KEY ("id")
+);
+
+-- LexwareVoucher Indizes
+CREATE UNIQUE INDEX "lexware_vouchers_tenant_id_lexware_voucher_id_key"
+  ON "app_crm"."lexware_vouchers"("tenant_id", "lexware_voucher_id");
+
+CREATE INDEX "lexware_vouchers_tenant_id_idx"
+  ON "app_crm"."lexware_vouchers"("tenant_id");
+
+CREATE INDEX "lexware_vouchers_tenant_id_company_id_idx"
+  ON "app_crm"."lexware_vouchers"("tenant_id", "company_id");
+
+CREATE INDEX "lexware_vouchers_tenant_id_contact_id_idx"
+  ON "app_crm"."lexware_vouchers"("tenant_id", "contact_id");
+
+CREATE INDEX "lexware_vouchers_tenant_id_lexware_contact_id_idx"
+  ON "app_crm"."lexware_vouchers"("tenant_id", "lexware_contact_id");
+
+CREATE INDEX "lexware_vouchers_tenant_id_voucher_type_idx"
+  ON "app_crm"."lexware_vouchers"("tenant_id", "voucher_type");
+
+-- LexwareVoucher Foreign Keys
+ALTER TABLE "app_crm"."lexware_vouchers"
+  ADD CONSTRAINT "lexware_vouchers_company_id_fkey"
+    FOREIGN KEY ("company_id") REFERENCES "app_crm"."companies"("id") ON DELETE SET NULL ON UPDATE CASCADE;
+
+ALTER TABLE "app_crm"."lexware_vouchers"
+  ADD CONSTRAINT "lexware_vouchers_contact_id_fkey"
+    FOREIGN KEY ("contact_id") REFERENCES "app_crm"."contacts"("id") ON DELETE SET NULL ON UPDATE CASCADE;
+
+-- DealVoucher Join-Tabelle
+CREATE TABLE "app_crm"."deal_vouchers" (
+  "id" UUID NOT NULL DEFAULT gen_random_uuid(),
+  "tenant_id" UUID NOT NULL,
+  "deal_id" UUID NOT NULL,
+  "voucher_id" UUID NOT NULL,
+  "linked_by" UUID NOT NULL,
+  "linked_at" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+
+  CONSTRAINT "deal_vouchers_pkey" PRIMARY KEY ("id")
+);
+
+-- DealVoucher Indizes
+CREATE UNIQUE INDEX "deal_vouchers_deal_id_voucher_id_key"
+  ON "app_crm"."deal_vouchers"("deal_id", "voucher_id");
+
+CREATE INDEX "deal_vouchers_tenant_id_idx"
+  ON "app_crm"."deal_vouchers"("tenant_id");
+
+CREATE INDEX "deal_vouchers_tenant_id_deal_id_idx"
+  ON "app_crm"."deal_vouchers"("tenant_id", "deal_id");
+
+CREATE INDEX "deal_vouchers_tenant_id_voucher_id_idx"
+  ON "app_crm"."deal_vouchers"("tenant_id", "voucher_id");
+
+-- DealVoucher Foreign Keys
+ALTER TABLE "app_crm"."deal_vouchers"
+  ADD CONSTRAINT "deal_vouchers_deal_id_fkey"
+    FOREIGN KEY ("deal_id") REFERENCES "app_crm"."deals"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+
+ALTER TABLE "app_crm"."deal_vouchers"
+  ADD CONSTRAINT "deal_vouchers_voucher_id_fkey"
+    FOREIGN KEY ("voucher_id") REFERENCES "app_crm"."lexware_vouchers"("id") ON DELETE CASCADE ON UPDATE CASCADE;
--- a/packages/crm-service/src/app.module.ts
+++ b/packages/crm-service/src/app.module.ts
@ -1,5 +1,6 @@
 import { Module } from '@nestjs/common';
 import { ConfigModule } from '@nestjs/config';
+import { ScheduleModule } from '@nestjs/schedule';
 import { APP_GUARD, APP_FILTER } from '@nestjs/core';
 import { validate } from './config/env.validation';
 import { CrmPrismaModule } from './prisma/crm-prisma.module';
@ -13,6 +14,7 @@ import { ActivitiesModule } from './activities/activities.module';
 import { PipelinesModule } from './pipelines/pipelines.module';
 import { DealsModule } from './deals/deals.module';
 import { CompaniesModule } from './companies/companies.module';
+import { LexwareModule } from './lexware/lexware.module';

@Module({
  imports: [
@ -20,6 +22,7 @@ import { CompaniesModule } from './companies/companies.module';
      isGlobal: true,
      validate,
    }),
+    ScheduleModule.forRoot(),
    CrmPrismaModule,
    RedisModule,
    AuthModule,
@ -29,6 +32,7 @@ import { CompaniesModule } from './companies/companies.module';
    PipelinesModule,
    DealsModule,
    CompaniesModule,
+    LexwareModule,
  ],
  providers: [
    {
--- a/packages/crm-service/src/companies/companies.module.ts
+++ b/packages/crm-service/src/companies/companies.module.ts
@ -2,9 +2,10 @@ import { Module } from '@nestjs/common';
 import { CompaniesController } from './companies.controller';
 import { CompaniesService } from './companies.service';
 import { CrmPrismaModule } from '../prisma/crm-prisma.module';
+import { LexwareModule } from '../lexware/lexware.module';

@Module({
-  imports: [CrmPrismaModule],
+  imports: [CrmPrismaModule, LexwareModule],
  controllers: [CompaniesController],
  providers: [CompaniesService],
  exports: [CompaniesService],
--- a/packages/crm-service/src/companies/companies.service.ts
+++ b/packages/crm-service/src/companies/companies.service.ts
@ -1,13 +1,19 @@
-import { Injectable, NotFoundException } from '@nestjs/common';
+import { Injectable, Logger, NotFoundException } from '@nestjs/common';
 import { CrmPrismaService } from '../prisma/crm-prisma.service';
 import { CreateCompanyDto } from './dto/create-company.dto';
 import { UpdateCompanyDto } from './dto/update-company.dto';
 import { QueryCompaniesDto } from './dto/query-companies.dto';
+import { LexwareContactsService } from '../lexware/lexware-contacts.service';
 import { Prisma } from '.prisma/crm-client';

@Injectable()
 export class CompaniesService {
-  constructor(private readonly prisma: CrmPrismaService) {}
+  private readonly logger = new Logger(CompaniesService.name);
+
+  constructor(
+    private readonly prisma: CrmPrismaService,
+    private readonly lexwareContacts: LexwareContactsService,
+  ) {}

  async create(tenantId: string, userId: string, dto: CreateCompanyDto) {
    return this.prisma.company.create({
@ -106,7 +112,9 @@ export class CompaniesService {
            stage: { select: { id: true, name: true, color: true } },
          },
        },
-        _count: { select: { contacts: true, deals: true } },
+        _count: {
+          select: { contacts: true, deals: true, lexwareVouchers: true },
+        },
      },
    });

@ -125,7 +133,7 @@ export class CompaniesService {
  ) {
    await this.findOne(tenantId, id);

-    return this.prisma.company.update({
+    const updated = await this.prisma.company.update({
      where: { id },
      data: {
        ...dto,
@ -135,6 +143,19 @@ export class CompaniesService {
        _count: { select: { contacts: true, deals: true } },
      },
    });
+
+    // ERP-Push: Wenn Lexware verknuepft UND "ERP"-Tag gesetzt → async Push
+    if (updated.lexwareContactId && updated.tags.includes('ERP')) {
+      this.lexwareContacts
+        .pushCompanyToLexware(tenantId, id)
+        .catch((err: Error) =>
+          this.logger.warn(
+            `ERP-Push nach Update fehlgeschlagen fuer Company "${updated.name}": ${err.message}`,
+          ),
+        );
+    }
+
+    return updated;
  }

  async remove(tenantId: string, id: string) {
--- a/packages/crm-service/src/config/env.validation.ts
+++ b/packages/crm-service/src/config/env.validation.ts
@ -39,6 +39,15 @@ export class EnvironmentVariables {
  @IsString()
  @IsOptional()
  CORS_ORIGINS?: string;
+
+  // Lexware Office Integration (optional)
+  @IsString()
+  @IsOptional()
+  LEXWARE_API_KEY?: string;
+
+  @IsString()
+  @IsOptional()
+  LEXWARE_API_URL?: string;
 }

 export function validate(
--- a/packages/crm-service/src/contacts/contacts.module.ts
+++ b/packages/crm-service/src/contacts/contacts.module.ts
@ -1,8 +1,10 @@
 import { Module } from '@nestjs/common';
 import { ContactsController } from './contacts.controller';
 import { ContactsService } from './contacts.service';
+import { LexwareModule } from '../lexware/lexware.module';

@Module({
+  imports: [LexwareModule],
  controllers: [ContactsController],
  providers: [ContactsService],
  exports: [ContactsService],
--- a/packages/crm-service/src/contacts/contacts.service.ts
+++ b/packages/crm-service/src/contacts/contacts.service.ts
@ -1,13 +1,19 @@
-import { Injectable, NotFoundException } from '@nestjs/common';
+import { Injectable, Logger, NotFoundException } from '@nestjs/common';
 import { CrmPrismaService } from '../prisma/crm-prisma.service';
 import { CreateContactDto } from './dto/create-contact.dto';
 import { UpdateContactDto } from './dto/update-contact.dto';
 import { QueryContactsDto } from './dto/query-contacts.dto';
+import { LexwareContactsService } from '../lexware/lexware-contacts.service';
 import { Prisma } from '.prisma/crm-client';

@Injectable()
 export class ContactsService {
-  constructor(private readonly prisma: CrmPrismaService) {}
+  private readonly logger = new Logger(ContactsService.name);
+
+  constructor(
+    private readonly prisma: CrmPrismaService,
+    private readonly lexwareContacts: LexwareContactsService,
+  ) {}

  async create(tenantId: string, userId: string, dto: CreateContactDto) {
    return this.prisma.contact.create({
@ -107,13 +113,26 @@ export class ContactsService {
  ) {
    await this.findOne(tenantId, id);

-    return this.prisma.contact.update({
+    const updated = await this.prisma.contact.update({
      where: { id },
      data: {
        ...dto,
        updatedBy: userId,
      },
    });
+
+    // ERP-Push: Wenn Lexware verknuepft UND "ERP"-Tag gesetzt → async Push
+    if (updated.lexwareContactId && updated.tags.includes('ERP')) {
+      this.lexwareContacts
+        .pushContactToLexware(tenantId, id)
+        .catch((err: Error) =>
+          this.logger.warn(
+            `ERP-Push nach Update fehlgeschlagen fuer Contact "${updated.firstName} ${updated.lastName}": ${err.message}`,
+          ),
+        );
+    }
+
+    return updated;
  }

  async remove(tenantId: string, id: string) {
--- a/packages/crm-service/src/deals/deals.service.ts
+++ b/packages/crm-service/src/deals/deals.service.ts
@ -158,6 +158,24 @@ export class DealsService {
        stage: true,
        contact: true,
        company: true,
+        dealVouchers: {
+          include: {
+            voucher: {
+              select: {
+                id: true,
+                voucherType: true,
+                voucherNumber: true,
+                voucherDate: true,
+                voucherStatus: true,
+                totalGrossAmount: true,
+                currency: true,
+                title: true,
+                lexwareDeepLink: true,
+              },
+            },
+          },
+          orderBy: { linkedAt: 'desc' },
+        },
      },
    });

--- a/packages/crm-service/src/health/health.controller.ts
+++ b/packages/crm-service/src/health/health.controller.ts
@ -1,8 +1,9 @@
-import { Controller, Get } from '@nestjs/common';
+import { Controller, Get, Inject, Optional } from '@nestjs/common';
 import { ApiTags, ApiOperation } from '@nestjs/swagger';
 import { Public } from '../common/decorators/public.decorator';
 import { CrmPrismaService } from '../prisma/crm-prisma.service';
 import { RedisService } from '../redis/redis.service';
+import { LexwareClientService } from '../lexware/lexware-client.service';

 interface HealthResponse {
  status: 'ok' | 'error';
@ -12,6 +13,7 @@ interface HealthResponse {
  services: {
    database: 'up' | 'down';
    redis: 'up' | 'down';
+    lexware: 'up' | 'down' | 'unconfigured';
  };
 }

@ -21,35 +23,39 @@ export class HealthController {
  constructor(
    private readonly prisma: CrmPrismaService,
    private readonly redis: RedisService,
+    @Optional() @Inject(LexwareClientService)
+    private readonly lexwareClient?: LexwareClientService,
  ) {}

  @Get()
  @Public()
  @ApiOperation({ summary: 'Health-Check fuer CRM-Service' })
  async check(): Promise<HealthResponse> {
-    const [dbStatus, redisStatus] = await Promise.allSettled([
+    const [dbStatus, redisStatus, lexwareStatus] = await Promise.allSettled([
      this.checkDatabase(),
      this.checkRedis(),
+      this.checkLexware(),
    ]);

-    const allUp =
-      dbStatus.status === 'fulfilled' &&
-      dbStatus.value &&
-      redisStatus.status === 'fulfilled' &&
-      redisStatus.value;
+    const dbOk = dbStatus.status === 'fulfilled' && dbStatus.value;
+    const redisOk = redisStatus.status === 'fulfilled' && redisStatus.value;
+    const lexwareResult: 'up' | 'down' | 'unconfigured' =
+      lexwareStatus.status === 'fulfilled'
+        ? lexwareStatus.value
+        : 'down';
+
+    // Lexware "unconfigured" ist kein Fehler
+    const allUp = dbOk && redisOk && lexwareResult !== 'down';

    return {
      status: allUp ? 'ok' : 'error',
      service: 'crm-service',
      timestamp: new Date().toISOString(),
-      version: '0.1.0',
+      version: '0.2.0',
      services: {
-        database:
-          dbStatus.status === 'fulfilled' && dbStatus.value ? 'up' : 'down',
-        redis:
-          redisStatus.status === 'fulfilled' && redisStatus.value
-            ? 'up'
-            : 'down',
+        database: dbOk ? 'up' : 'down',
+        redis: redisOk ? 'up' : 'down',
+        lexware: lexwareResult,
      },
    };
  }
@ -71,4 +77,9 @@ export class HealthController {
      return false;
    }
  }
+
+  private async checkLexware(): Promise<'up' | 'down' | 'unconfigured'> {
+    if (!this.lexwareClient) return 'unconfigured';
+    return this.lexwareClient.isHealthy();
+  }
 }
--- a/packages/crm-service/src/health/health.module.ts
+++ b/packages/crm-service/src/health/health.module.ts
@ -1,7 +1,9 @@
 import { Module } from '@nestjs/common';
 import { HealthController } from './health.controller';
+import { LexwareModule } from '../lexware/lexware.module';

@Module({
+  imports: [LexwareModule],
  controllers: [HealthController],
 })
 export class HealthModule {}
--- a/packages/crm-service/src/lexware/dto/link-deal-voucher.dto.ts
+++ b/packages/crm-service/src/lexware/dto/link-deal-voucher.dto.ts
@ -0,0 +1,8 @@
+import { ApiProperty } from '@nestjs/swagger';
+import { IsUUID } from 'class-validator';
+
+export class LinkDealVoucherDto {
+  @ApiProperty({ description: 'CRM LexwareVoucher UUID (gecachter Beleg)' })
+  @IsUUID()
+  voucherId!: string;
+}
--- a/packages/crm-service/src/lexware/dto/link-lexware-contact.dto.ts
+++ b/packages/crm-service/src/lexware/dto/link-lexware-contact.dto.ts
@ -0,0 +1,28 @@
+import { ApiProperty } from '@nestjs/swagger';
+import { IsString, IsUUID } from 'class-validator';
+
+export class LinkLexwareToCompanyDto {
+  @ApiProperty({ description: 'CRM Company UUID' })
+  @IsUUID()
+  companyId!: string;
+
+  @ApiProperty({ description: 'Lexware Office Contact ID' })
+  @IsString()
+  lexwareContactId!: string;
+}
+
+export class LinkLexwareToContactDto {
+  @ApiProperty({ description: 'CRM Contact UUID' })
+  @IsUUID()
+  contactId!: string;
+
+  @ApiProperty({ description: 'Lexware Office Contact ID' })
+  @IsString()
+  lexwareContactId!: string;
+}
+
+export class ImportLexwareContactDto {
+  @ApiProperty({ description: 'Lexware Office Contact ID' })
+  @IsString()
+  lexwareContactId!: string;
+}
--- a/packages/crm-service/src/lexware/dto/query-lexware-vouchers.dto.ts
+++ b/packages/crm-service/src/lexware/dto/query-lexware-vouchers.dto.ts
@ -0,0 +1,36 @@
+import { ApiPropertyOptional } from '@nestjs/swagger';
+import { IsOptional, IsString, IsNumber, IsEnum, Min, Max } from 'class-validator';
+
+export enum VoucherTypeFilter {
+  QUOTATION = 'QUOTATION',
+  ORDER_CONFIRMATION = 'ORDER_CONFIRMATION',
+  INVOICE = 'INVOICE',
+  CREDIT_NOTE = 'CREDIT_NOTE',
+}
+
+export class QueryLexwareVouchersDto {
+  @ApiPropertyOptional({ enum: VoucherTypeFilter })
+  @IsOptional()
+  @IsEnum(VoucherTypeFilter)
+  voucherType?: VoucherTypeFilter;
+
+  @ApiPropertyOptional({
+    description: 'Beleg-Status (draft, open, paidoff, voided)',
+  })
+  @IsOptional()
+  @IsString()
+  voucherStatus?: string;
+
+  @ApiPropertyOptional({ default: 1 })
+  @IsOptional()
+  @IsNumber()
+  @Min(1)
+  page?: number;
+
+  @ApiPropertyOptional({ default: 25, maximum: 100 })
+  @IsOptional()
+  @IsNumber()
+  @Min(1)
+  @Max(100)
+  pageSize?: number;
+}
--- a/packages/crm-service/src/lexware/dto/search-lexware-contacts.dto.ts
+++ b/packages/crm-service/src/lexware/dto/search-lexware-contacts.dto.ts
@ -0,0 +1,50 @@
+import { ApiPropertyOptional } from '@nestjs/swagger';
+import {
+  IsOptional,
+  IsString,
+  MinLength,
+  IsBoolean,
+  IsNumber,
+} from 'class-validator';
+
+export class SearchLexwareContactsDto {
+  @ApiPropertyOptional({ description: 'Suche nach Name (min 3 Zeichen)' })
+  @IsOptional()
+  @IsString()
+  @MinLength(3)
+  name?: string;
+
+  @ApiPropertyOptional({ description: 'Suche nach E-Mail (min 3 Zeichen)' })
+  @IsOptional()
+  @IsString()
+  @MinLength(3)
+  email?: string;
+
+  @ApiPropertyOptional({ description: 'Exakte Kunden-/Lieferantennummer' })
+  @IsOptional()
+  @IsNumber()
+  number?: number;
+
+  @ApiPropertyOptional({
+    description: 'Nur Kunden anzeigen',
+    default: true,
+  })
+  @IsOptional()
+  @IsBoolean()
+  customer?: boolean;
+
+  @ApiPropertyOptional({ description: 'Nur Lieferanten anzeigen' })
+  @IsOptional()
+  @IsBoolean()
+  vendor?: boolean;
+
+  @ApiPropertyOptional({ description: 'Seite (0-basiert)', default: 0 })
+  @IsOptional()
+  @IsNumber()
+  page?: number;
+
+  @ApiPropertyOptional({ description: 'Seitengroesse', default: 25 })
+  @IsOptional()
+  @IsNumber()
+  size?: number;
+}
--- a/packages/crm-service/src/lexware/interfaces/lexware-api.interfaces.ts
+++ b/packages/crm-service/src/lexware/interfaces/lexware-api.interfaces.ts
@ -0,0 +1,214 @@
+// ============================================================
+// Lexware Office API - TypeScript Interfaces
+// ============================================================
+// Basiert auf: https://developers.lexware.io/docs/
+// ============================================================
+
+// --------------------------------------------------------
+// Contact Interfaces
+// --------------------------------------------------------
+
+export interface LexwareContactPerson {
+  salutation?: string;
+  firstName?: string;
+  lastName?: string;
+}
+
+export interface LexwareContactCompany {
+  name?: string;
+  taxNumber?: string;
+  vatRegistrationId?: string;
+  allowTaxFreeInvoices?: boolean;
+  contactPersons?: LexwareContactPersonEntry[];
+}
+
+export interface LexwareContactPersonEntry {
+  salutation?: string;
+  firstName?: string;
+  lastName?: string;
+  primary?: boolean;
+  emailAddress?: string;
+  phoneNumber?: string;
+}
+
+export interface LexwareAddress {
+  supplement?: string;
+  street?: string;
+  zip?: string;
+  city?: string;
+  countryCode?: string;
+}
+
+export interface LexwareEmailAddresses {
+  business?: string[];
+  office?: string[];
+  private?: string[];
+  other?: string[];
+}
+
+export interface LexwarePhoneNumbers {
+  business?: string[];
+  office?: string[];
+  mobile?: string[];
+  private?: string[];
+  fax?: string[];
+  other?: string[];
+}
+
+export interface LexwareContactRoles {
+  customer?: { number?: number };
+  vendor?: { number?: number };
+}
+
+export interface LexwareContact {
+  id: string;
+  organizationId?: string;
+  version: number;
+  roles: LexwareContactRoles;
+  company?: LexwareContactCompany;
+  person?: LexwareContactPerson;
+  addresses?: {
+    billing?: LexwareAddress[];
+    shipping?: LexwareAddress[];
+  };
+  emailAddresses?: LexwareEmailAddresses;
+  phoneNumbers?: LexwarePhoneNumbers;
+  note?: string;
+  archived?: boolean;
+}
+
+export interface LexwareContactListResponse {
+  content: LexwareContact[];
+  first: boolean;
+  last: boolean;
+  totalPages: number;
+  totalElements: number;
+  numberOfElements: number;
+  size: number;
+  number: number;
+}
+
+export interface LexwareContactCreateResponse {
+  id: string;
+  resourceUri: string;
+  createdDate: string;
+  updatedDate: string;
+  version: number;
+}
+
+// --------------------------------------------------------
+// Voucher / Beleg Interfaces
+// --------------------------------------------------------
+
+export interface LexwareVoucherListItem {
+  voucherId: string;
+  voucherType: string;
+  voucherNumber: string;
+  voucherDate: string;
+  voucherStatus: string;
+  totalAmount: number;
+  currency: string;
+  contactId?: string;
+  contactName?: string;
+}
+
+export interface LexwareVoucherListResponse {
+  content: LexwareVoucherListItem[];
+  first: boolean;
+  last: boolean;
+  totalPages: number;
+  totalElements: number;
+  size: number;
+  number: number;
+}
+
+export interface LexwareLineItem {
+  id?: string;
+  type: string;
+  name: string;
+  description?: string;
+  quantity: number;
+  unitName?: string;
+  unitPrice?: {
+    currency: string;
+    netAmount: number;
+    grossAmount: number;
+    taxRatePercentage: number;
+  };
+  lineItemAmount?: number;
+}
+
+export interface LexwareTotalPrice {
+  currency: string;
+  totalNetAmount: number;
+  totalGrossAmount: number;
+  totalTaxAmount: number;
+  totalDiscountAbsolute?: number;
+  totalDiscountPercentage?: number;
+}
+
+export interface LexwareVoucherAddress {
+  contactId?: string;
+  name?: string;
+  supplement?: string;
+  street?: string;
+  city?: string;
+  zip?: string;
+  countryCode?: string;
+  contactPerson?: string;
+}
+
+export interface LexwareVoucherDetail {
+  id: string;
+  organizationId?: string;
+  voucherNumber?: string;
+  voucherDate?: string;
+  voucherStatus?: string;
+  createdDate?: string;
+  updatedDate?: string;
+  version?: number;
+  archived?: boolean;
+  language?: string;
+  address?: LexwareVoucherAddress;
+  lineItems?: LexwareLineItem[];
+  totalPrice?: LexwareTotalPrice;
+  taxConditions?: {
+    taxType?: string;
+  };
+  title?: string;
+  introduction?: string;
+  remark?: string;
+  relatedVouchers?: Array<{
+    id: string;
+    voucherNumber: string;
+    voucherType: string;
+  }>;
+}
+
+// Type alias fuer spezifische Voucher-Typen (gleiche Struktur)
+export type LexwareInvoiceDetail = LexwareVoucherDetail & {
+  paymentConditions?: {
+    paymentTermLabel?: string;
+    dueDate?: string;
+  };
+  shippingConditions?: {
+    shippingConditionsLabel?: string;
+    deliveryTerms?: string;
+  };
+};
+
+export type LexwareQuotationDetail = LexwareVoucherDetail;
+export type LexwareOrderConfirmationDetail = LexwareVoucherDetail;
+export type LexwareCreditNoteDetail = LexwareVoucherDetail;
+
+// --------------------------------------------------------
+// Event Subscription Interfaces
+// --------------------------------------------------------
+
+export interface LexwareEventSubscription {
+  subscriptionId: string;
+  organizationId: string;
+  createdDate: string;
+  eventType: string;
+  callbackUrl: string;
+}
--- a/packages/crm-service/src/lexware/lexware-client.service.ts
+++ b/packages/crm-service/src/lexware/lexware-client.service.ts
@ -0,0 +1,183 @@
+// ============================================================
+// Lexware Office API - Rate-limited HTTP Client
+// ============================================================
+
+import {
+  Injectable,
+  Logger,
+  OnModuleInit,
+  ServiceUnavailableException,
+} from '@nestjs/common';
+import { ConfigService } from '@nestjs/config';
+import { HttpService } from '@nestjs/axios';
+import { AxiosError } from 'axios';
+import { firstValueFrom } from 'rxjs';
+import { RateLimiter } from './utils/rate-limiter';
+
+@Injectable()
+export class LexwareClientService implements OnModuleInit {
+  private readonly logger = new Logger(LexwareClientService.name);
+  private readonly rateLimiter: RateLimiter;
+  private enabled = false;
+
+  constructor(
+    private readonly httpService: HttpService,
+    private readonly config: ConfigService,
+  ) {
+    const rateLimit = this.config.get<number>('LEXWARE_RATE_LIMIT', 2);
+    this.rateLimiter = new RateLimiter(rateLimit, rateLimit);
+  }
+
+  async onModuleInit(): Promise<void> {
+    const apiKey = this.config.get<string>('LEXWARE_API_KEY');
+    if (!apiKey) {
+      this.logger.warn(
+        'LEXWARE_API_KEY nicht konfiguriert. Lexware-Integration deaktiviert.',
+      );
+      this.enabled = false;
+      return;
+    }
+
+    this.enabled = true;
+    this.logger.log('Lexware Office Integration aktiviert.');
+  }
+
+  /**
+   * Prueft ob die Lexware-Integration konfiguriert und erreichbar ist.
+   */
+  isEnabled(): boolean {
+    return this.enabled;
+  }
+
+  /**
+   * Health-Check: Prueft Lexware API Erreichbarkeit.
+   */
+  async isHealthy(): Promise<'up' | 'down' | 'unconfigured'> {
+    if (!this.enabled) return 'unconfigured';
+
+    try {
+      await this.get<unknown>('/v1/profile');
+      return 'up';
+    } catch {
+      return 'down';
+    }
+  }
+
+  /**
+   * GET Request an Lexware API (rate-limited).
+   */
+  async get<T>(
+    path: string,
+    params?: Record<string, string | number | boolean>,
+  ): Promise<T> {
+    this.ensureEnabled();
+    return this.executeWithRetry<T>('GET', path, undefined, params);
+  }
+
+  /**
+   * POST Request an Lexware API (rate-limited).
+   */
+  async post<T>(path: string, body: unknown): Promise<T> {
+    this.ensureEnabled();
+    return this.executeWithRetry<T>('POST', path, body);
+  }
+
+  /**
+   * PUT Request an Lexware API (rate-limited).
+   */
+  async put<T>(path: string, body: unknown): Promise<T> {
+    this.ensureEnabled();
+    return this.executeWithRetry<T>('PUT', path, body);
+  }
+
+  /**
+   * DELETE Request an Lexware API (rate-limited).
+   */
+  async delete(path: string): Promise<void> {
+    this.ensureEnabled();
+    await this.executeWithRetry<void>('DELETE', path);
+  }
+
+  // --------------------------------------------------------
+  // Internes: Retry-Logik mit Rate Limiting
+  // --------------------------------------------------------
+
+  private async executeWithRetry<T>(
+    method: string,
+    path: string,
+    body?: unknown,
+    params?: Record<string, string | number | boolean>,
+    retries = 3,
+  ): Promise<T> {
+    for (let attempt = 1; attempt <= retries; attempt++) {
+      try {
+        await this.rateLimiter.acquire();
+
+        const response = await firstValueFrom(
+          method === 'GET'
+            ? this.httpService.get<T>(path, { params })
+            : method === 'POST'
+              ? this.httpService.post<T>(path, body)
+              : method === 'PUT'
+                ? this.httpService.put<T>(path, body)
+                : this.httpService.delete<T>(path),
+        );
+
+        return response.data;
+      } catch (error) {
+        const axiosError = error as AxiosError;
+        const status = axiosError.response?.status;
+
+        // 429 Too Many Requests -> Backoff und Retry
+        if (status === 429 && attempt < retries) {
+          const backoffMs = Math.pow(2, attempt) * 1000; // 2s, 4s
+          this.logger.warn(
+            `Lexware Rate Limit erreicht (429). Warte ${backoffMs}ms (Versuch ${attempt}/${retries})`,
+          );
+          await new Promise((resolve) => setTimeout(resolve, backoffMs));
+          continue;
+        }
+
+        // 401/403 -> API Key Problem
+        if (status === 401 || status === 403) {
+          this.logger.error(
+            `Lexware API Authentifizierungsfehler (${status}). API Key pruefen.`,
+          );
+          throw new ServiceUnavailableException(
+            'Lexware Office API nicht erreichbar (Authentifizierung fehlgeschlagen)',
+          );
+        }
+
+        // Andere Fehler oder letzter Retry
+        if (attempt === retries) {
+          const msg =
+            axiosError.response?.statusText ||
+            axiosError.message ||
+            'Unbekannter Fehler';
+          this.logger.error(
+            `Lexware API Fehler: ${method} ${path} -> ${status || 'NETWORK'}: ${msg}`,
+          );
+          throw error;
+        }
+
+        // Netzwerk-Fehler -> kurzer Backoff
+        const backoffMs = attempt * 1000;
+        this.logger.warn(
+          `Lexware API Fehler (${status || 'NETWORK'}). Retry in ${backoffMs}ms (${attempt}/${retries})`,
+        );
+        await new Promise((resolve) => setTimeout(resolve, backoffMs));
+      }
+    }
+
+    // Sollte nicht erreicht werden
+    throw new ServiceUnavailableException('Lexware API nicht erreichbar');
+  }
+
+  private ensureEnabled(): void {
+    if (!this.enabled) {
+      throw new ServiceUnavailableException(
+        'Lexware Office Integration ist nicht konfiguriert. LEXWARE_API_KEY fehlt.',
+      );
+    }
+  }
+}
--- a/packages/crm-service/src/lexware/lexware-contacts.controller.ts
+++ b/packages/crm-service/src/lexware/lexware-contacts.controller.ts
@ -0,0 +1,214 @@
+// ============================================================
+// Lexware Office - Contacts REST Controller
+// ============================================================
+
+import {
+  Controller,
+  Get,
+  Post,
+  Delete,
+  Body,
+  Param,
+  Query,
+  ParseUUIDPipe,
+  HttpCode,
+  HttpStatus,
+  UseGuards,
+} from '@nestjs/common';
+import {
+  ApiTags,
+  ApiOperation,
+  ApiBearerAuth,
+  ApiParam,
+} from '@nestjs/swagger';
+import { TenantGuard } from '../auth/guards/tenant.guard';
+import { CurrentUser, JwtPayload } from '../common/decorators';
+import { singleResponse } from '../common/dto/pagination.dto';
+import { LexwareContactsService } from './lexware-contacts.service';
+import { SearchLexwareContactsDto } from './dto/search-lexware-contacts.dto';
+import {
+  LinkLexwareToCompanyDto,
+  LinkLexwareToContactDto,
+  ImportLexwareContactDto,
+} from './dto/link-lexware-contact.dto';
+
+@ApiTags('Lexware Office - Kontakte')
+@ApiBearerAuth('access-token')
+@UseGuards(TenantGuard)
+@Controller('lexware/contacts')
+export class LexwareContactsController {
+  constructor(private readonly service: LexwareContactsService) {}
+
+  @Get('search')
+  @ApiOperation({
+    summary: 'Lexware-Kontakte suchen (Proxy zu Lexware Office API)',
+  })
+  async search(@Query() query: SearchLexwareContactsDto) {
+    const result = await this.service.searchContacts(query);
+    return {
+      success: true,
+      data: result.content,
+      pagination: {
+        page: result.number + 1, // Lexware ist 0-basiert, CRM 1-basiert
+        pageSize: result.size,
+        total: result.totalElements,
+        totalPages: result.totalPages,
+      },
+      meta: { timestamp: new Date().toISOString() },
+    };
+  }
+
+  @Post('link-company')
+  @HttpCode(HttpStatus.OK)
+  @ApiOperation({
+    summary: 'Lexware-Kontakt mit CRM-Unternehmen verknuepfen',
+  })
+  async linkCompany(
+    @CurrentUser() user: JwtPayload,
+    @Body() dto: LinkLexwareToCompanyDto,
+  ) {
+    const result = await this.service.linkToCompany(
+      user.tenantId!,
+      dto.companyId,
+      dto.lexwareContactId,
+      user.sub,
+    );
+    return singleResponse(result);
+  }
+
+  @Post('link-contact')
+  @HttpCode(HttpStatus.OK)
+  @ApiOperation({
+    summary: 'Lexware-Kontakt mit CRM-Kontakt verknuepfen',
+  })
+  async linkContact(
+    @CurrentUser() user: JwtPayload,
+    @Body() dto: LinkLexwareToContactDto,
+  ) {
+    const result = await this.service.linkToContact(
+      user.tenantId!,
+      dto.contactId,
+      dto.lexwareContactId,
+      user.sub,
+    );
+    return singleResponse(result);
+  }
+
+  @Delete('unlink-company/:companyId')
+  @ApiOperation({ summary: 'Lexware-Verknuepfung von Unternehmen loesen' })
+  @ApiParam({ name: 'companyId', type: 'string', format: 'uuid' })
+  async unlinkCompany(
+    @CurrentUser() user: JwtPayload,
+    @Param('companyId', ParseUUIDPipe) companyId: string,
+  ) {
+    const result = await this.service.unlinkCompany(
+      user.tenantId!,
+      companyId,
+      user.sub,
+    );
+    return singleResponse(result);
+  }
+
+  @Delete('unlink-contact/:contactId')
+  @ApiOperation({ summary: 'Lexware-Verknuepfung von Kontakt loesen' })
+  @ApiParam({ name: 'contactId', type: 'string', format: 'uuid' })
+  async unlinkContact(
+    @CurrentUser() user: JwtPayload,
+    @Param('contactId', ParseUUIDPipe) contactId: string,
+  ) {
+    const result = await this.service.unlinkContact(
+      user.tenantId!,
+      contactId,
+      user.sub,
+    );
+    return singleResponse(result);
+  }
+
+  @Post('import-company')
+  @HttpCode(HttpStatus.CREATED)
+  @ApiOperation({
+    summary: 'Neues CRM-Unternehmen aus Lexware-Kontakt erstellen',
+  })
+  async importCompany(
+    @CurrentUser() user: JwtPayload,
+    @Body() dto: ImportLexwareContactDto,
+  ) {
+    const result = await this.service.importAsCompany(
+      user.tenantId!,
+      dto.lexwareContactId,
+      user.sub,
+    );
+    return singleResponse(result);
+  }
+
+  @Post('import-contact')
+  @HttpCode(HttpStatus.CREATED)
+  @ApiOperation({
+    summary: 'Neuen CRM-Kontakt aus Lexware-Kontakt erstellen',
+  })
+  async importContact(
+    @CurrentUser() user: JwtPayload,
+    @Body() dto: ImportLexwareContactDto,
+  ) {
+    const result = await this.service.importAsContact(
+      user.tenantId!,
+      dto.lexwareContactId,
+      user.sub,
+    );
+    return singleResponse(result);
+  }
+
+  @Post('push/:entityType/:entityId')
+  @HttpCode(HttpStatus.OK)
+  @ApiOperation({ summary: 'CRM-Entity nach Lexware pushen (ERP)' })
+  @ApiParam({ name: 'entityType', enum: ['company', 'contact'] })
+  @ApiParam({ name: 'entityId', type: 'string', format: 'uuid' })
+  async push(
+    @CurrentUser() user: JwtPayload,
+    @Param('entityType') entityType: string,
+    @Param('entityId', ParseUUIDPipe) entityId: string,
+  ) {
+    if (entityType === 'company') {
+      const result = await this.service.pushCompanyToLexware(
+        user.tenantId!,
+        entityId,
+      );
+      return singleResponse(result);
+    } else {
+      const result = await this.service.pushContactToLexware(
+        user.tenantId!,
+        entityId,
+      );
+      return singleResponse(result);
+    }
+  }
+
+  @Post('sync/:entityType/:entityId')
+  @HttpCode(HttpStatus.OK)
+  @ApiOperation({
+    summary: 'Daten aus Lexware in CRM-Entity aktualisieren',
+  })
+  @ApiParam({ name: 'entityType', enum: ['company', 'contact'] })
+  @ApiParam({ name: 'entityId', type: 'string', format: 'uuid' })
+  async sync(
+    @CurrentUser() user: JwtPayload,
+    @Param('entityType') entityType: string,
+    @Param('entityId', ParseUUIDPipe) entityId: string,
+  ) {
+    if (entityType === 'company') {
+      const result = await this.service.syncCompanyFromLexware(
+        user.tenantId!,
+        entityId,
+        user.sub,
+      );
+      return singleResponse(result);
+    } else {
+      const result = await this.service.syncContactFromLexware(
+        user.tenantId!,
+        entityId,
+        user.sub,
+      );
+      return singleResponse(result);
+    }
+  }
+}
--- a/packages/crm-service/src/lexware/lexware-contacts.service.ts
+++ b/packages/crm-service/src/lexware/lexware-contacts.service.ts
@ -0,0 +1,452 @@
+// ============================================================
+// Lexware Office - Contact Operations Service
+// ============================================================
+
+import {
+  Injectable,
+  Logger,
+  NotFoundException,
+  ConflictException,
+} from '@nestjs/common';
+import { CrmPrismaService } from '../prisma/crm-prisma.service';
+import { LexwareClientService } from './lexware-client.service';
+import { SearchLexwareContactsDto } from './dto/search-lexware-contacts.dto';
+import {
+  LexwareContact,
+  LexwareContactListResponse,
+  LexwareContactCreateResponse,
+} from './interfaces/lexware-api.interfaces';
+import {
+  lexwareContactToCompanyData,
+  lexwareContactToContactData,
+  companyToLexwareContactBody,
+  contactToLexwareContactBody,
+} from './utils/lexware-mapper';
+
+@Injectable()
+export class LexwareContactsService {
+  private readonly logger = new Logger(LexwareContactsService.name);
+
+  constructor(
+    private readonly prisma: CrmPrismaService,
+    private readonly lexwareClient: LexwareClientService,
+  ) {}
+
+  // --------------------------------------------------------
+  // Suche in Lexware Office
+  // --------------------------------------------------------
+
+  async searchContacts(
+    query: SearchLexwareContactsDto,
+  ): Promise<LexwareContactListResponse> {
+    const params: Record<string, string | number | boolean> = {};
+
+    if (query.name) params.name = query.name;
+    if (query.email) params.email = query.email;
+    if (query.number !== undefined) params.number = query.number;
+    if (query.customer !== undefined) params.customer = query.customer;
+    if (query.vendor !== undefined) params.vendor = query.vendor;
+    if (query.page !== undefined) params.page = query.page;
+    if (query.size !== undefined) params.size = query.size;
+
+    return this.lexwareClient.get<LexwareContactListResponse>(
+      '/v1/contacts',
+      params,
+    );
+  }
+
+  async getContact(lexwareContactId: string): Promise<LexwareContact> {
+    return this.lexwareClient.get<LexwareContact>(
+      `/v1/contacts/${lexwareContactId}`,
+    );
+  }
+
+  // --------------------------------------------------------
+  // Link Lexware Contact -> CRM Company
+  // --------------------------------------------------------
+
+  async linkToCompany(
+    tenantId: string,
+    companyId: string,
+    lexwareContactId: string,
+    userId: string,
+  ) {
+    // Pruefe ob Company existiert
+    const company = await this.prisma.company.findFirst({
+      where: { id: companyId, tenantId },
+    });
+    if (!company) {
+      throw new NotFoundException('Unternehmen nicht gefunden');
+    }
+
+    // Pruefe ob Lexware-Kontakt bereits verknuepft
+    const existing = await this.prisma.company.findFirst({
+      where: { tenantId, lexwareContactId },
+    });
+    if (existing && existing.id !== companyId) {
+      throw new ConflictException(
+        `Lexware-Kontakt ist bereits mit Unternehmen "${existing.name}" verknuepft`,
+      );
+    }
+
+    // Auch bei Contacts pruefen
+    const existingContact = await this.prisma.contact.findFirst({
+      where: { tenantId, lexwareContactId },
+    });
+    if (existingContact) {
+      throw new ConflictException(
+        `Lexware-Kontakt ist bereits mit Kontakt "${existingContact.firstName} ${existingContact.lastName}" verknuepft`,
+      );
+    }
+
+    // Lexware-Kontakt laden und Version speichern
+    const lexwareContact = await this.getContact(lexwareContactId);
+
+    return this.prisma.company.update({
+      where: { id: companyId },
+      data: {
+        lexwareContactId,
+        lexwareContactVersion: lexwareContact.version,
+        lexwareSyncedAt: new Date(),
+        updatedBy: userId,
+      },
+    });
+  }
+
+  // --------------------------------------------------------
+  // Link Lexware Contact -> CRM Contact
+  // --------------------------------------------------------
+
+  async linkToContact(
+    tenantId: string,
+    contactId: string,
+    lexwareContactId: string,
+    userId: string,
+  ) {
+    const contact = await this.prisma.contact.findFirst({
+      where: { id: contactId, tenantId },
+    });
+    if (!contact) {
+      throw new NotFoundException('Kontakt nicht gefunden');
+    }
+
+    // Pruefe ob Lexware-Kontakt bereits verknuepft
+    const existingContact = await this.prisma.contact.findFirst({
+      where: { tenantId, lexwareContactId },
+    });
+    if (existingContact && existingContact.id !== contactId) {
+      throw new ConflictException(
+        `Lexware-Kontakt ist bereits mit Kontakt "${existingContact.firstName} ${existingContact.lastName}" verknuepft`,
+      );
+    }
+
+    const existingCompany = await this.prisma.company.findFirst({
+      where: { tenantId, lexwareContactId },
+    });
+    if (existingCompany) {
+      throw new ConflictException(
+        `Lexware-Kontakt ist bereits mit Unternehmen "${existingCompany.name}" verknuepft`,
+      );
+    }
+
+    const lexwareContact = await this.getContact(lexwareContactId);
+
+    return this.prisma.contact.update({
+      where: { id: contactId },
+      data: {
+        lexwareContactId,
+        lexwareContactVersion: lexwareContact.version,
+        lexwareSyncedAt: new Date(),
+        updatedBy: userId,
+      },
+    });
+  }
+
+  // --------------------------------------------------------
+  // Unlink
+  // --------------------------------------------------------
+
+  async unlinkCompany(tenantId: string, companyId: string, userId: string) {
+    const company = await this.prisma.company.findFirst({
+      where: { id: companyId, tenantId },
+    });
+    if (!company) {
+      throw new NotFoundException('Unternehmen nicht gefunden');
+    }
+
+    return this.prisma.company.update({
+      where: { id: companyId },
+      data: {
+        lexwareContactId: null,
+        lexwareContactVersion: null,
+        lexwareSyncedAt: null,
+        updatedBy: userId,
+      },
+    });
+  }
+
+  async unlinkContact(tenantId: string, contactId: string, userId: string) {
+    const contact = await this.prisma.contact.findFirst({
+      where: { id: contactId, tenantId },
+    });
+    if (!contact) {
+      throw new NotFoundException('Kontakt nicht gefunden');
+    }
+
+    return this.prisma.contact.update({
+      where: { id: contactId },
+      data: {
+        lexwareContactId: null,
+        lexwareContactVersion: null,
+        lexwareSyncedAt: null,
+        updatedBy: userId,
+      },
+    });
+  }
+
+  // --------------------------------------------------------
+  // Import: Lexware -> Neue CRM Entity
+  // --------------------------------------------------------
+
+  async importAsCompany(
+    tenantId: string,
+    lexwareContactId: string,
+    userId: string,
+  ) {
+    // Pruefe ob bereits verknuepft
+    const existing = await this.prisma.company.findFirst({
+      where: { tenantId, lexwareContactId },
+    });
+    if (existing) {
+      throw new ConflictException(
+        `Lexware-Kontakt ist bereits mit Unternehmen "${existing.name}" verknuepft`,
+      );
+    }
+
+    const lexwareContact = await this.getContact(lexwareContactId);
+    const companyData = lexwareContactToCompanyData(lexwareContact);
+
+    return this.prisma.company.create({
+      data: {
+        tenantId,
+        ...companyData,
+        lexwareContactId,
+        lexwareContactVersion: lexwareContact.version,
+        lexwareSyncedAt: new Date(),
+        createdBy: userId,
+      },
+      include: {
+        _count: { select: { contacts: true, deals: true } },
+      },
+    });
+  }
+
+  async importAsContact(
+    tenantId: string,
+    lexwareContactId: string,
+    userId: string,
+  ) {
+    const existing = await this.prisma.contact.findFirst({
+      where: { tenantId, lexwareContactId },
+    });
+    if (existing) {
+      throw new ConflictException(
+        `Lexware-Kontakt ist bereits mit Kontakt "${existing.firstName} ${existing.lastName}" verknuepft`,
+      );
+    }
+
+    const lexwareContact = await this.getContact(lexwareContactId);
+    const contactData = lexwareContactToContactData(lexwareContact);
+
+    return this.prisma.contact.create({
+      data: {
+        tenantId,
+        ...contactData,
+        lexwareContactId,
+        lexwareContactVersion: lexwareContact.version,
+        lexwareSyncedAt: new Date(),
+        createdBy: userId,
+      },
+    });
+  }
+
+  // --------------------------------------------------------
+  // Push: CRM -> Lexware (ERP-Tag)
+  // --------------------------------------------------------
+
+  async pushCompanyToLexware(tenantId: string, companyId: string) {
+    const company = await this.prisma.company.findFirst({
+      where: { id: companyId, tenantId },
+    });
+    if (!company) {
+      throw new NotFoundException('Unternehmen nicht gefunden');
+    }
+
+    const body = companyToLexwareContactBody(company);
+
+    if (company.lexwareContactId) {
+      // Update: Hole aktuelle Version von Lexware
+      const current = await this.getContact(company.lexwareContactId);
+      const updateBody = { ...body, version: current.version };
+
+      try {
+        await this.lexwareClient.put(
+          `/v1/contacts/${company.lexwareContactId}`,
+          updateBody,
+        );
+      } catch (error: unknown) {
+        const axiosError = error as { response?: { status?: number } };
+        if (axiosError.response?.status === 409) {
+          this.logger.warn(
+            `Optimistic Locking Konflikt beim Update von Lexware-Kontakt ${company.lexwareContactId}. Ueberspringe.`,
+          );
+          return company;
+        }
+        throw error;
+      }
+
+      return this.prisma.company.update({
+        where: { id: companyId },
+        data: {
+          lexwareContactVersion: current.version + 1,
+          lexwareSyncedAt: new Date(),
+        },
+      });
+    } else {
+      // Create: Neuen Lexware-Kontakt erstellen
+      const result =
+        await this.lexwareClient.post<LexwareContactCreateResponse>(
+          '/v1/contacts',
+          body,
+        );
+
+      return this.prisma.company.update({
+        where: { id: companyId },
+        data: {
+          lexwareContactId: result.id,
+          lexwareContactVersion: result.version,
+          lexwareSyncedAt: new Date(),
+        },
+      });
+    }
+  }
+
+  async pushContactToLexware(tenantId: string, contactId: string) {
+    const contact = await this.prisma.contact.findFirst({
+      where: { id: contactId, tenantId },
+    });
+    if (!contact) {
+      throw new NotFoundException('Kontakt nicht gefunden');
+    }
+
+    const body = contactToLexwareContactBody(contact);
+
+    if (contact.lexwareContactId) {
+      const current = await this.getContact(contact.lexwareContactId);
+      const updateBody = { ...body, version: current.version };
+
+      try {
+        await this.lexwareClient.put(
+          `/v1/contacts/${contact.lexwareContactId}`,
+          updateBody,
+        );
+      } catch (error: unknown) {
+        const axiosError = error as { response?: { status?: number } };
+        if (axiosError.response?.status === 409) {
+          this.logger.warn(
+            `Optimistic Locking Konflikt beim Update von Lexware-Kontakt ${contact.lexwareContactId}. Ueberspringe.`,
+          );
+          return contact;
+        }
+        throw error;
+      }
+
+      return this.prisma.contact.update({
+        where: { id: contactId },
+        data: {
+          lexwareContactVersion: current.version + 1,
+          lexwareSyncedAt: new Date(),
+        },
+      });
+    } else {
+      const result =
+        await this.lexwareClient.post<LexwareContactCreateResponse>(
+          '/v1/contacts',
+          body,
+        );
+
+      return this.prisma.contact.update({
+        where: { id: contactId },
+        data: {
+          lexwareContactId: result.id,
+          lexwareContactVersion: result.version,
+          lexwareSyncedAt: new Date(),
+        },
+      });
+    }
+  }
+
+  // --------------------------------------------------------
+  // Sync: Lexware -> CRM (Daten aktualisieren)
+  // --------------------------------------------------------
+
+  async syncCompanyFromLexware(
+    tenantId: string,
+    companyId: string,
+    userId: string,
+  ) {
+    const company = await this.prisma.company.findFirst({
+      where: { id: companyId, tenantId },
+    });
+    if (!company) {
+      throw new NotFoundException('Unternehmen nicht gefunden');
+    }
+    if (!company.lexwareContactId) {
+      throw new NotFoundException(
+        'Unternehmen ist nicht mit Lexware verknuepft',
+      );
+    }
+
+    const lexwareContact = await this.getContact(company.lexwareContactId);
+    const companyData = lexwareContactToCompanyData(lexwareContact);
+
+    return this.prisma.company.update({
+      where: { id: companyId },
+      data: {
+        ...companyData,
+        lexwareContactVersion: lexwareContact.version,
+        lexwareSyncedAt: new Date(),
+        updatedBy: userId,
+      },
+    });
+  }
+
+  async syncContactFromLexware(
+    tenantId: string,
+    contactId: string,
+    userId: string,
+  ) {
+    const contact = await this.prisma.contact.findFirst({
+      where: { id: contactId, tenantId },
+    });
+    if (!contact) {
+      throw new NotFoundException('Kontakt nicht gefunden');
+    }
+    if (!contact.lexwareContactId) {
+      throw new NotFoundException('Kontakt ist nicht mit Lexware verknuepft');
+    }
+
+    const lexwareContact = await this.getContact(contact.lexwareContactId);
+    const contactData = lexwareContactToContactData(lexwareContact);
+
+    return this.prisma.contact.update({
+      where: { id: contactId },
+      data: {
+        ...contactData,
+        lexwareContactVersion: lexwareContact.version,
+        lexwareSyncedAt: new Date(),
+        updatedBy: userId,
+      },
+    });
+  }
+}
--- a/packages/crm-service/src/lexware/lexware-sync.service.ts
+++ b/packages/crm-service/src/lexware/lexware-sync.service.ts
@ -0,0 +1,210 @@
+// ============================================================
+// Lexware Office - Sync Jobs (Cron)
+// ============================================================
+
+import { Injectable, Logger } from '@nestjs/common';
+import { Cron, CronExpression } from '@nestjs/schedule';
+import { CrmPrismaService } from '../prisma/crm-prisma.service';
+import { RedisService } from '../redis/redis.service';
+import { LexwareClientService } from './lexware-client.service';
+import { LexwareContactsService } from './lexware-contacts.service';
+import { LexwareVouchersService } from './lexware-vouchers.service';
+
+@Injectable()
+export class LexwareSyncService {
+  private readonly logger = new Logger(LexwareSyncService.name);
+
+  constructor(
+    private readonly prisma: CrmPrismaService,
+    private readonly redis: RedisService,
+    private readonly lexwareClient: LexwareClientService,
+    private readonly contactsService: LexwareContactsService,
+    private readonly vouchersService: LexwareVouchersService,
+  ) {}
+
+  // --------------------------------------------------------
+  // Job 1: Beleg-Cache aktualisieren (alle 4 Stunden)
+  // --------------------------------------------------------
+
+  @Cron(CronExpression.EVERY_4_HOURS)
+  async syncVouchers(): Promise<void> {
+    if (!this.lexwareClient.isEnabled()) return;
+
+    // Distributed Lock: Nur eine Instanz gleichzeitig
+    const lockKey = 'lexware:sync:vouchers:lock';
+    const acquired = await this.acquireLock(lockKey, 1800); // 30 Min Lock
+    if (!acquired) {
+      this.logger.log('Beleg-Sync: Lock nicht erhalten. Ueberspringe.');
+      return;
+    }
+
+    try {
+      this.logger.log('Starte Beleg-Sync fuer alle verknuepften Entitaeten...');
+
+      // Alle Companies mit Lexware-Verknuepfung
+      const companies = await this.prisma.company.findMany({
+        where: { lexwareContactId: { not: null } },
+        select: {
+          id: true,
+          tenantId: true,
+          lexwareContactId: true,
+          name: true,
+        },
+      });
+
+      for (const company of companies) {
+        try {
+          await this.vouchersService.fetchAndCacheVouchers(
+            company.tenantId,
+            company.lexwareContactId!,
+            company.id,
+            null,
+          );
+        } catch (error) {
+          this.logger.warn(
+            `Beleg-Sync fehlgeschlagen fuer Company "${company.name}": ${error instanceof Error ? error.message : 'Unbekannt'}`,
+          );
+        }
+      }
+
+      // Alle Contacts mit Lexware-Verknuepfung
+      const contacts = await this.prisma.contact.findMany({
+        where: { lexwareContactId: { not: null } },
+        select: {
+          id: true,
+          tenantId: true,
+          lexwareContactId: true,
+          firstName: true,
+          lastName: true,
+        },
+      });
+
+      for (const contact of contacts) {
+        try {
+          await this.vouchersService.fetchAndCacheVouchers(
+            contact.tenantId,
+            contact.lexwareContactId!,
+            null,
+            contact.id,
+          );
+        } catch (error) {
+          this.logger.warn(
+            `Beleg-Sync fehlgeschlagen fuer Contact "${contact.firstName} ${contact.lastName}": ${error instanceof Error ? error.message : 'Unbekannt'}`,
+          );
+        }
+      }
+
+      this.logger.log(
+        `Beleg-Sync abgeschlossen. ${companies.length} Companies, ${contacts.length} Contacts verarbeitet.`,
+      );
+    } finally {
+      await this.releaseLock(lockKey);
+    }
+  }
+
+  // --------------------------------------------------------
+  // Job 2: ERP-Tag Push (alle 30 Minuten)
+  // --------------------------------------------------------
+
+  @Cron('0 */30 * * * *')
+  async pushErpTaggedEntities(): Promise<void> {
+    if (!this.lexwareClient.isEnabled()) return;
+
+    const lockKey = 'lexware:sync:push:lock';
+    const acquired = await this.acquireLock(lockKey, 900); // 15 Min Lock
+    if (!acquired) {
+      this.logger.log('ERP-Push: Lock nicht erhalten. Ueberspringe.');
+      return;
+    }
+
+    try {
+      this.logger.log('Starte ERP-Push fuer getaggte Entitaeten...');
+
+      // Companies mit "ERP" Tag
+      const companies = await this.prisma.company.findMany({
+        where: {
+          tags: { has: 'ERP' },
+        },
+        select: {
+          id: true,
+          tenantId: true,
+          name: true,
+          lexwareContactId: true,
+        },
+      });
+
+      let pushCount = 0;
+      for (const company of companies) {
+        try {
+          await this.contactsService.pushCompanyToLexware(
+            company.tenantId,
+            company.id,
+          );
+          pushCount++;
+        } catch (error) {
+          this.logger.warn(
+            `ERP-Push fehlgeschlagen fuer Company "${company.name}": ${error instanceof Error ? error.message : 'Unbekannt'}`,
+          );
+        }
+      }
+
+      // Contacts mit "ERP" Tag
+      const contacts = await this.prisma.contact.findMany({
+        where: {
+          tags: { has: 'ERP' },
+        },
+        select: {
+          id: true,
+          tenantId: true,
+          firstName: true,
+          lastName: true,
+          lexwareContactId: true,
+        },
+      });
+
+      for (const contact of contacts) {
+        try {
+          await this.contactsService.pushContactToLexware(
+            contact.tenantId,
+            contact.id,
+          );
+          pushCount++;
+        } catch (error) {
+          this.logger.warn(
+            `ERP-Push fehlgeschlagen fuer Contact "${contact.firstName} ${contact.lastName}": ${error instanceof Error ? error.message : 'Unbekannt'}`,
+          );
+        }
+      }
+
+      this.logger.log(
+        `ERP-Push abgeschlossen. ${pushCount} von ${companies.length + contacts.length} Entitaeten gepusht.`,
+      );
+    } finally {
+      await this.releaseLock(lockKey);
+    }
+  }
+
+  // --------------------------------------------------------
+  // Distributed Lock (Redis SET NX EX)
+  // --------------------------------------------------------
+
+  private async acquireLock(
+    key: string,
+    ttlSeconds: number,
+  ): Promise<boolean> {
+    try {
+      const result = await this.redis.setNx(key, 'locked', ttlSeconds);
+      return result;
+    } catch {
+      return false;
+    }
+  }
+
+  private async releaseLock(key: string): Promise<void> {
+    try {
+      await this.redis.del(key);
+    } catch {
+      // Lock wird durch TTL automatisch freigegeben
+    }
+  }
+}
--- a/packages/crm-service/src/lexware/lexware-vouchers.controller.ts
+++ b/packages/crm-service/src/lexware/lexware-vouchers.controller.ts
@ -0,0 +1,190 @@
+// ============================================================
+// Lexware Office - Vouchers REST Controller
+// ============================================================
+
+import {
+  Controller,
+  Get,
+  Post,
+  Delete,
+  Body,
+  Param,
+  Query,
+  ParseUUIDPipe,
+  HttpCode,
+  HttpStatus,
+  UseGuards,
+} from '@nestjs/common';
+import {
+  ApiTags,
+  ApiOperation,
+  ApiBearerAuth,
+  ApiParam,
+} from '@nestjs/swagger';
+import { TenantGuard } from '../auth/guards/tenant.guard';
+import { CurrentUser, JwtPayload } from '../common/decorators';
+import {
+  paginatedResponse,
+  singleResponse,
+} from '../common/dto/pagination.dto';
+import { LexwareVouchersService } from './lexware-vouchers.service';
+import { QueryLexwareVouchersDto } from './dto/query-lexware-vouchers.dto';
+import { LinkDealVoucherDto } from './dto/link-deal-voucher.dto';
+
+@ApiTags('Lexware Office - Belege')
+@ApiBearerAuth('access-token')
+@UseGuards(TenantGuard)
+@Controller('lexware/vouchers')
+export class LexwareVouchersController {
+  constructor(private readonly service: LexwareVouchersService) {}
+
+  // --------------------------------------------------------
+  // Belege abrufen
+  // --------------------------------------------------------
+
+  @Get('company/:companyId')
+  @ApiOperation({ summary: 'Lexware-Belege fuer Unternehmen abrufen (Cache)' })
+  @ApiParam({ name: 'companyId', type: 'string', format: 'uuid' })
+  async getForCompany(
+    @CurrentUser() user: JwtPayload,
+    @Param('companyId', ParseUUIDPipe) companyId: string,
+    @Query() query: QueryLexwareVouchersDto,
+  ) {
+    const result = await this.service.getVouchersForCompany(
+      user.tenantId!,
+      companyId,
+      query,
+    );
+    return paginatedResponse(
+      result.data,
+      result.total,
+      result.page,
+      result.pageSize,
+    );
+  }
+
+  @Get('contact/:contactId')
+  @ApiOperation({ summary: 'Lexware-Belege fuer Kontakt abrufen (Cache)' })
+  @ApiParam({ name: 'contactId', type: 'string', format: 'uuid' })
+  async getForContact(
+    @CurrentUser() user: JwtPayload,
+    @Param('contactId', ParseUUIDPipe) contactId: string,
+    @Query() query: QueryLexwareVouchersDto,
+  ) {
+    const result = await this.service.getVouchersForContact(
+      user.tenantId!,
+      contactId,
+      query,
+    );
+    return paginatedResponse(
+      result.data,
+      result.total,
+      result.page,
+      result.pageSize,
+    );
+  }
+
+  @Get('deal/:dealId')
+  @ApiOperation({ summary: 'Lexware-Belege fuer Vorgang abrufen' })
+  @ApiParam({ name: 'dealId', type: 'string', format: 'uuid' })
+  async getForDeal(
+    @CurrentUser() user: JwtPayload,
+    @Param('dealId', ParseUUIDPipe) dealId: string,
+    @Query() query: QueryLexwareVouchersDto,
+  ) {
+    const result = await this.service.getVouchersForDeal(
+      user.tenantId!,
+      dealId,
+      query,
+    );
+    return paginatedResponse(
+      result.data,
+      result.total,
+      result.page,
+      result.pageSize,
+    );
+  }
+
+  // --------------------------------------------------------
+  // Beleg mit Vorgang verknuepfen / trennen
+  // --------------------------------------------------------
+
+  @Post('deal/:dealId/link')
+  @HttpCode(HttpStatus.CREATED)
+  @ApiOperation({ summary: 'Lexware-Beleg mit Vorgang verknuepfen' })
+  @ApiParam({ name: 'dealId', type: 'string', format: 'uuid' })
+  async linkToDeal(
+    @CurrentUser() user: JwtPayload,
+    @Param('dealId', ParseUUIDPipe) dealId: string,
+    @Body() dto: LinkDealVoucherDto,
+  ) {
+    const result = await this.service.linkVoucherToDeal(
+      user.tenantId!,
+      dealId,
+      dto.voucherId,
+      user.sub,
+    );
+    return singleResponse(result);
+  }
+
+  @Delete('deal/:dealId/unlink/:voucherId')
+  @ApiOperation({ summary: 'Lexware-Beleg von Vorgang trennen' })
+  @ApiParam({ name: 'dealId', type: 'string', format: 'uuid' })
+  @ApiParam({ name: 'voucherId', type: 'string', format: 'uuid' })
+  async unlinkFromDeal(
+    @CurrentUser() user: JwtPayload,
+    @Param('dealId', ParseUUIDPipe) dealId: string,
+    @Param('voucherId', ParseUUIDPipe) voucherId: string,
+  ) {
+    const result = await this.service.unlinkVoucherFromDeal(
+      user.tenantId!,
+      dealId,
+      voucherId,
+    );
+    return singleResponse(result);
+  }
+
+  // --------------------------------------------------------
+  // Cache manuell aktualisieren
+  // --------------------------------------------------------
+
+  @Post('refresh/company/:companyId')
+  @HttpCode(HttpStatus.OK)
+  @ApiOperation({
+    summary: 'Beleg-Cache fuer Unternehmen manuell aktualisieren',
+  })
+  @ApiParam({ name: 'companyId', type: 'string', format: 'uuid' })
+  async refreshCompany(
+    @CurrentUser() user: JwtPayload,
+    @Param('companyId', ParseUUIDPipe) companyId: string,
+  ) {
+    const count = await this.service.refreshCompanyVouchers(
+      user.tenantId!,
+      companyId,
+    );
+    return {
+      success: true,
+      data: { refreshedCount: count },
+      meta: { timestamp: new Date().toISOString() },
+    };
+  }
+
+  @Post('refresh/contact/:contactId')
+  @HttpCode(HttpStatus.OK)
+  @ApiOperation({ summary: 'Beleg-Cache fuer Kontakt manuell aktualisieren' })
+  @ApiParam({ name: 'contactId', type: 'string', format: 'uuid' })
+  async refreshContact(
+    @CurrentUser() user: JwtPayload,
+    @Param('contactId', ParseUUIDPipe) contactId: string,
+  ) {
+    const count = await this.service.refreshContactVouchers(
+      user.tenantId!,
+      contactId,
+    );
+    return {
+      success: true,
+      data: { refreshedCount: count },
+      meta: { timestamp: new Date().toISOString() },
+    };
+  }
+}
--- a/packages/crm-service/src/lexware/lexware-vouchers.service.ts
+++ b/packages/crm-service/src/lexware/lexware-vouchers.service.ts
@ -0,0 +1,381 @@
+// ============================================================
+// Lexware Office - Voucher Operations Service
+// ============================================================
+
+import {
+  Injectable,
+  Logger,
+  NotFoundException,
+  ConflictException,
+} from '@nestjs/common';
+import { Prisma } from '.prisma/crm-client';
+import { CrmPrismaService } from '../prisma/crm-prisma.service';
+import { LexwareClientService } from './lexware-client.service';
+import { QueryLexwareVouchersDto } from './dto/query-lexware-vouchers.dto';
+import {
+  LexwareVoucherListResponse,
+  LexwareVoucherDetail,
+} from './interfaces/lexware-api.interfaces';
+import {
+  voucherTypeFromLexware,
+  voucherTypeToLexwareEndpoint,
+  voucherDetailToCacheData,
+} from './utils/lexware-mapper';
+
+@Injectable()
+export class LexwareVouchersService {
+  private readonly logger = new Logger(LexwareVouchersService.name);
+
+  constructor(
+    private readonly prisma: CrmPrismaService,
+    private readonly lexwareClient: LexwareClientService,
+  ) {}
+
+  // --------------------------------------------------------
+  // Belege von Lexware laden und cachen
+  // --------------------------------------------------------
+
+  async fetchAndCacheVouchers(
+    tenantId: string,
+    lexwareContactId: string,
+    companyId?: string | null,
+    contactId?: string | null,
+  ): Promise<number> {
+    this.logger.log(
+      `Lade Belege fuer Lexware-Kontakt ${lexwareContactId}...`,
+    );
+
+    // Alle relevanten Belegtypen laden
+    const voucherTypes = [
+      'invoice',
+      'quotation',
+      'orderconfirmation',
+      'creditnote',
+    ];
+    let totalUpserted = 0;
+
+    for (const voucherType of voucherTypes) {
+      let page = 0;
+      let hasMore = true;
+
+      while (hasMore) {
+        const listResponse =
+          await this.lexwareClient.get<LexwareVoucherListResponse>(
+            '/v1/voucherlist',
+            {
+              contactId: lexwareContactId,
+              voucherType,
+              page,
+              size: 100,
+            },
+          );
+
+        for (const item of listResponse.content) {
+          try {
+            // Detail laden fuer vollstaendige Daten
+            const crmVoucherType = voucherTypeFromLexware(item.voucherType);
+            const endpoint = voucherTypeToLexwareEndpoint(crmVoucherType);
+            const detail =
+              await this.lexwareClient.get<LexwareVoucherDetail>(
+                `/v1/${endpoint}/${item.voucherId}`,
+              );
+
+            const cacheData = voucherDetailToCacheData(
+              detail,
+              crmVoucherType,
+              lexwareContactId,
+            );
+
+            // Upsert: Existierenden Beleg aktualisieren oder neuen anlegen
+            await this.prisma.lexwareVoucher.upsert({
+              where: {
+                tenantId_lexwareVoucherId: {
+                  tenantId,
+                  lexwareVoucherId: item.voucherId,
+                },
+              },
+              create: {
+                tenantId,
+                lexwareVoucherId: item.voucherId,
+                ...cacheData,
+                companyId: companyId || undefined,
+                contactId: contactId || undefined,
+                fetchedAt: new Date(),
+              },
+              update: {
+                ...cacheData,
+                companyId: companyId || undefined,
+                contactId: contactId || undefined,
+                fetchedAt: new Date(),
+              },
+            });
+
+            totalUpserted++;
+          } catch (error) {
+            this.logger.warn(
+              `Fehler beim Laden von Beleg ${item.voucherId}: ${error instanceof Error ? error.message : 'Unbekannt'}`,
+            );
+          }
+        }
+
+        hasMore = !listResponse.last;
+        page++;
+      }
+    }
+
+    this.logger.log(
+      `${totalUpserted} Belege fuer Lexware-Kontakt ${lexwareContactId} gecacht.`,
+    );
+    return totalUpserted;
+  }
+
+  // --------------------------------------------------------
+  // Belege fuer Company abrufen (aus Cache)
+  // --------------------------------------------------------
+
+  async getVouchersForCompany(
+    tenantId: string,
+    companyId: string,
+    query: QueryLexwareVouchersDto,
+  ) {
+    const company = await this.prisma.company.findFirst({
+      where: { id: companyId, tenantId },
+    });
+    if (!company) {
+      throw new NotFoundException('Unternehmen nicht gefunden');
+    }
+
+    return this.queryVouchers(tenantId, { companyId }, query);
+  }
+
+  // --------------------------------------------------------
+  // Belege fuer Contact abrufen (aus Cache)
+  // --------------------------------------------------------
+
+  async getVouchersForContact(
+    tenantId: string,
+    contactId: string,
+    query: QueryLexwareVouchersDto,
+  ) {
+    const contact = await this.prisma.contact.findFirst({
+      where: { id: contactId, tenantId },
+    });
+    if (!contact) {
+      throw new NotFoundException('Kontakt nicht gefunden');
+    }
+
+    return this.queryVouchers(tenantId, { contactId }, query);
+  }
+
+  // --------------------------------------------------------
+  // Belege fuer Deal abrufen (ueber DealVoucher Join-Table)
+  // --------------------------------------------------------
+
+  async getVouchersForDeal(
+    tenantId: string,
+    dealId: string,
+    query: QueryLexwareVouchersDto,
+  ) {
+    const deal = await this.prisma.deal.findFirst({
+      where: { id: dealId, tenantId },
+    });
+    if (!deal) {
+      throw new NotFoundException('Vorgang nicht gefunden');
+    }
+
+    const page = query.page ?? 1;
+    const pageSize = query.pageSize ?? 25;
+
+    const where: Prisma.DealVoucherWhereInput = {
+      tenantId,
+      dealId,
+    };
+
+    // Filter auf Voucher-Ebene
+    const voucherWhere: Prisma.LexwareVoucherWhereInput = {};
+    if (query.voucherType) {
+      voucherWhere.voucherType = query.voucherType;
+    }
+    if (query.voucherStatus) {
+      voucherWhere.voucherStatus = query.voucherStatus;
+    }
+
+    if (Object.keys(voucherWhere).length > 0) {
+      where.voucher = voucherWhere;
+    }
+
+    const [dealVouchers, total] = await Promise.all([
+      this.prisma.dealVoucher.findMany({
+        where,
+        skip: (page - 1) * pageSize,
+        take: pageSize,
+        orderBy: { linkedAt: 'desc' },
+        include: {
+          voucher: true,
+        },
+      }),
+      this.prisma.dealVoucher.count({ where }),
+    ]);
+
+    return {
+      data: dealVouchers.map((dv) => ({
+        ...dv.voucher,
+        linkedBy: dv.linkedBy,
+        linkedAt: dv.linkedAt,
+        dealVoucherId: dv.id,
+      })),
+      total,
+      page,
+      pageSize,
+    };
+  }
+
+  // --------------------------------------------------------
+  // Beleg mit Deal verknuepfen
+  // --------------------------------------------------------
+
+  async linkVoucherToDeal(
+    tenantId: string,
+    dealId: string,
+    voucherId: string,
+    userId: string,
+  ) {
+    // Deal pruefen
+    const deal = await this.prisma.deal.findFirst({
+      where: { id: dealId, tenantId },
+    });
+    if (!deal) {
+      throw new NotFoundException('Vorgang nicht gefunden');
+    }
+
+    // Voucher pruefen
+    const voucher = await this.prisma.lexwareVoucher.findFirst({
+      where: { id: voucherId, tenantId },
+    });
+    if (!voucher) {
+      throw new NotFoundException('Beleg nicht gefunden');
+    }
+
+    // Pruefe ob bereits verknuepft
+    const existing = await this.prisma.dealVoucher.findUnique({
+      where: { dealId_voucherId: { dealId, voucherId } },
+    });
+    if (existing) {
+      throw new ConflictException('Beleg ist bereits mit diesem Vorgang verknuepft');
+    }
+
+    return this.prisma.dealVoucher.create({
+      data: {
+        tenantId,
+        dealId,
+        voucherId,
+        linkedBy: userId,
+      },
+      include: {
+        voucher: true,
+      },
+    });
+  }
+
+  // --------------------------------------------------------
+  // Beleg von Deal trennen
+  // --------------------------------------------------------
+
+  async unlinkVoucherFromDeal(
+    tenantId: string,
+    dealId: string,
+    voucherId: string,
+  ) {
+    const dealVoucher = await this.prisma.dealVoucher.findFirst({
+      where: { tenantId, dealId, voucherId },
+    });
+    if (!dealVoucher) {
+      throw new NotFoundException('Verknuepfung nicht gefunden');
+    }
+
+    return this.prisma.dealVoucher.delete({
+      where: { id: dealVoucher.id },
+    });
+  }
+
+  // --------------------------------------------------------
+  // Cache manuell aktualisieren
+  // --------------------------------------------------------
+
+  async refreshCompanyVouchers(tenantId: string, companyId: string) {
+    const company = await this.prisma.company.findFirst({
+      where: { id: companyId, tenantId },
+    });
+    if (!company) {
+      throw new NotFoundException('Unternehmen nicht gefunden');
+    }
+    if (!company.lexwareContactId) {
+      throw new NotFoundException(
+        'Unternehmen ist nicht mit Lexware verknuepft',
+      );
+    }
+
+    return this.fetchAndCacheVouchers(
+      tenantId,
+      company.lexwareContactId,
+      companyId,
+      null,
+    );
+  }
+
+  async refreshContactVouchers(tenantId: string, contactId: string) {
+    const contact = await this.prisma.contact.findFirst({
+      where: { id: contactId, tenantId },
+    });
+    if (!contact) {
+      throw new NotFoundException('Kontakt nicht gefunden');
+    }
+    if (!contact.lexwareContactId) {
+      throw new NotFoundException('Kontakt ist nicht mit Lexware verknuepft');
+    }
+
+    return this.fetchAndCacheVouchers(
+      tenantId,
+      contact.lexwareContactId,
+      null,
+      contactId,
+    );
+  }
+
+  // --------------------------------------------------------
+  // Interne Hilfsfunktion: Paginierte Voucher-Abfrage
+  // --------------------------------------------------------
+
+  private async queryVouchers(
+    tenantId: string,
+    filter: { companyId?: string; contactId?: string },
+    query: QueryLexwareVouchersDto,
+  ) {
+    const page = query.page ?? 1;
+    const pageSize = query.pageSize ?? 25;
+
+    const where: Prisma.LexwareVoucherWhereInput = {
+      tenantId,
+      ...filter,
+    };
+
+    if (query.voucherType) {
+      where.voucherType = query.voucherType;
+    }
+    if (query.voucherStatus) {
+      where.voucherStatus = query.voucherStatus;
+    }
+
+    const [data, total] = await Promise.all([
+      this.prisma.lexwareVoucher.findMany({
+        where,
+        skip: (page - 1) * pageSize,
+        take: pageSize,
+        orderBy: { voucherDate: 'desc' },
+      }),
+      this.prisma.lexwareVoucher.count({ where }),
+    ]);
+
+    return { data, total, page, pageSize };
+  }
+}
--- a/packages/crm-service/src/lexware/lexware.module.ts
+++ b/packages/crm-service/src/lexware/lexware.module.ts
@ -0,0 +1,46 @@
+// ============================================================
+// Lexware Office Integration - NestJS Module
+// ============================================================
+
+import { Module } from '@nestjs/common';
+import { HttpModule } from '@nestjs/axios';
+import { ConfigService } from '@nestjs/config';
+import { CrmPrismaModule } from '../prisma/crm-prisma.module';
+import { RedisModule } from '../redis/redis.module';
+import { LexwareClientService } from './lexware-client.service';
+import { LexwareContactsService } from './lexware-contacts.service';
+import { LexwareVouchersService } from './lexware-vouchers.service';
+import { LexwareSyncService } from './lexware-sync.service';
+import { LexwareContactsController } from './lexware-contacts.controller';
+import { LexwareVouchersController } from './lexware-vouchers.controller';
+
+@Module({
+  imports: [
+    HttpModule.registerAsync({
+      useFactory: (config: ConfigService) => ({
+        baseURL: config.get<string>(
+          'LEXWARE_API_URL',
+          'https://api.lexware.io',
+        ),
+        timeout: 15000,
+        headers: {
+          Authorization: `Bearer ${config.get<string>('LEXWARE_API_KEY', '')}`,
+          Accept: 'application/json',
+          'Content-Type': 'application/json',
+        },
+      }),
+      inject: [ConfigService],
+    }),
+    CrmPrismaModule,
+    RedisModule,
+  ],
+  controllers: [LexwareContactsController, LexwareVouchersController],
+  providers: [
+    LexwareClientService,
+    LexwareContactsService,
+    LexwareVouchersService,
+    LexwareSyncService,
+  ],
+  exports: [LexwareContactsService, LexwareVouchersService, LexwareClientService],
+})
+export class LexwareModule {}
--- a/packages/crm-service/src/lexware/utils/lexware-mapper.ts
+++ b/packages/crm-service/src/lexware/utils/lexware-mapper.ts
@ -0,0 +1,334 @@
+// ============================================================
+// Mapping-Funktionen: Lexware Office <-> CRM
+// ============================================================
+
+import { VoucherType } from '.prisma/crm-client';
+import {
+  LexwareContact,
+  LexwareVoucherDetail,
+  LexwareVoucherListItem,
+} from '../interfaces/lexware-api.interfaces';
+
+// --------------------------------------------------------
+// Lexware Contact -> CRM Company
+// --------------------------------------------------------
+export function lexwareContactToCompanyData(lc: LexwareContact): {
+  name: string;
+  email?: string;
+  phone?: string;
+  website?: string;
+  street?: string;
+  zip?: string;
+  city?: string;
+  country?: string;
+  notes?: string;
+} {
+  const name =
+    lc.company?.name || [lc.person?.firstName, lc.person?.lastName].filter(Boolean).join(' ') || 'Unbekannt';
+
+  const billingAddr = lc.addresses?.billing?.[0];
+  const email = getFirstEmail(lc);
+  const phone = getFirstPhone(lc);
+
+  return {
+    name,
+    email: email || undefined,
+    phone: phone || undefined,
+    street: billingAddr?.street || undefined,
+    zip: billingAddr?.zip || undefined,
+    city: billingAddr?.city || undefined,
+    country: billingAddr?.countryCode || 'DE',
+    notes: lc.note || undefined,
+  };
+}
+
+// --------------------------------------------------------
+// Lexware Contact -> CRM Contact
+// --------------------------------------------------------
+export function lexwareContactToContactData(lc: LexwareContact): {
+  firstName?: string;
+  lastName?: string;
+  companyName?: string;
+  position?: string;
+  email?: string;
+  phone?: string;
+  mobile?: string;
+  street?: string;
+  zip?: string;
+  city?: string;
+  country?: string;
+  notes?: string;
+  type: 'PERSON' | 'ORGANIZATION';
+} {
+  const isPerson = !!lc.person;
+  const billingAddr = lc.addresses?.billing?.[0];
+  const email = getFirstEmail(lc);
+  const phone = getFirstPhone(lc);
+  const mobile = lc.phoneNumbers?.mobile?.[0];
+
+  if (isPerson) {
+    return {
+      type: 'PERSON',
+      firstName: lc.person?.firstName || undefined,
+      lastName: lc.person?.lastName || 'Unbekannt',
+      companyName: lc.company?.name || undefined,
+      position: lc.company?.contactPersons?.[0]?.primary
+        ? 'Primaerkontakt'
+        : undefined,
+      email: email || undefined,
+      phone: phone || undefined,
+      mobile: mobile || undefined,
+      street: billingAddr?.street || undefined,
+      zip: billingAddr?.zip || undefined,
+      city: billingAddr?.city || undefined,
+      country: billingAddr?.countryCode || 'DE',
+      notes: lc.note || undefined,
+    };
+  }
+
+  return {
+    type: 'ORGANIZATION',
+    firstName: lc.company?.contactPersons?.[0]?.firstName || undefined,
+    lastName:
+      lc.company?.contactPersons?.[0]?.lastName || lc.company?.name || 'Unbekannt',
+    companyName: lc.company?.name || undefined,
+    email: email || undefined,
+    phone: phone || undefined,
+    mobile: mobile || undefined,
+    street: billingAddr?.street || undefined,
+    zip: billingAddr?.zip || undefined,
+    city: billingAddr?.city || undefined,
+    country: billingAddr?.countryCode || 'DE',
+    notes: lc.note || undefined,
+  };
+}
+
+// --------------------------------------------------------
+// CRM Company -> Lexware Contact Body (fuer POST/PUT)
+// --------------------------------------------------------
+export function companyToLexwareContactBody(company: {
+  name: string;
+  email?: string | null;
+  phone?: string | null;
+  street?: string | null;
+  zip?: string | null;
+  city?: string | null;
+  country?: string | null;
+  notes?: string | null;
+}): Record<string, unknown> {
+  const body: Record<string, unknown> = {
+    version: 0,
+    roles: { customer: {} },
+    company: { name: company.name },
+  };
+
+  if (company.street || company.zip || company.city) {
+    body.addresses = {
+      billing: [
+        {
+          street: company.street || undefined,
+          zip: company.zip || undefined,
+          city: company.city || undefined,
+          countryCode: company.country || 'DE',
+        },
+      ],
+    };
+  }
+
+  if (company.email) {
+    body.emailAddresses = { business: [company.email] };
+  }
+
+  if (company.phone) {
+    body.phoneNumbers = { business: [company.phone] };
+  }
+
+  if (company.notes) {
+    body.note = company.notes.substring(0, 1000);
+  }
+
+  return body;
+}
+
+// --------------------------------------------------------
+// CRM Contact -> Lexware Contact Body (fuer POST/PUT)
+// --------------------------------------------------------
+export function contactToLexwareContactBody(contact: {
+  firstName?: string | null;
+  lastName?: string | null;
+  companyName?: string | null;
+  email?: string | null;
+  phone?: string | null;
+  mobile?: string | null;
+  street?: string | null;
+  zip?: string | null;
+  city?: string | null;
+  country?: string | null;
+  notes?: string | null;
+  type: string;
+}): Record<string, unknown> {
+  const body: Record<string, unknown> = {
+    version: 0,
+    roles: { customer: {} },
+  };
+
+  if (contact.type === 'ORGANIZATION' && contact.companyName) {
+    body.company = { name: contact.companyName };
+  } else {
+    body.person = {
+      firstName: contact.firstName || undefined,
+      lastName: contact.lastName || 'Unbekannt',
+    };
+  }
+
+  if (contact.street || contact.zip || contact.city) {
+    body.addresses = {
+      billing: [
+        {
+          street: contact.street || undefined,
+          zip: contact.zip || undefined,
+          city: contact.city || undefined,
+          countryCode: contact.country || 'DE',
+        },
+      ],
+    };
+  }
+
+  if (contact.email) {
+    body.emailAddresses = { business: [contact.email] };
+  }
+
+  const phoneNumbers: Record<string, string[]> = {};
+  if (contact.phone) phoneNumbers.business = [contact.phone];
+  if (contact.mobile) phoneNumbers.mobile = [contact.mobile];
+  if (Object.keys(phoneNumbers).length > 0) {
+    body.phoneNumbers = phoneNumbers;
+  }
+
+  if (contact.notes) {
+    body.note = contact.notes.substring(0, 1000);
+  }
+
+  return body;
+}
+
+// --------------------------------------------------------
+// Voucher Type Mapping
+// --------------------------------------------------------
+export function voucherTypeFromLexware(lexwareType: string): VoucherType {
+  const map: Record<string, VoucherType> = {
+    invoice: 'INVOICE',
+    quotation: 'QUOTATION',
+    orderconfirmation: 'ORDER_CONFIRMATION',
+    creditnote: 'CREDIT_NOTE',
+  };
+  return map[lexwareType.toLowerCase()] || 'INVOICE';
+}
+
+export function voucherTypeToLexwareEndpoint(type: VoucherType): string {
+  const map: Record<VoucherType, string> = {
+    INVOICE: 'invoices',
+    QUOTATION: 'quotations',
+    ORDER_CONFIRMATION: 'order-confirmations',
+    CREDIT_NOTE: 'credit-notes',
+  };
+  return map[type];
+}
+
+// --------------------------------------------------------
+// Deep Link Builder
+// --------------------------------------------------------
+export function buildLexwareDeepLink(
+  voucherType: VoucherType,
+  voucherId: string,
+): string {
+  const typeMap: Record<VoucherType, string> = {
+    INVOICE: 'invoices',
+    QUOTATION: 'quotations',
+    ORDER_CONFIRMATION: 'order-confirmations',
+    CREDIT_NOTE: 'credit-notes',
+  };
+  const typePath = typeMap[voucherType];
+  return `https://app.lexware.de/permalink/${typePath}/view/${voucherId}`;
+}
+
+// --------------------------------------------------------
+// Lexware Voucher Detail -> CRM Cache Daten
+// --------------------------------------------------------
+export function voucherDetailToCacheData(
+  detail: LexwareVoucherDetail,
+  voucherType: VoucherType,
+  lexwareContactId: string,
+): {
+  voucherType: VoucherType;
+  voucherNumber: string | null;
+  voucherDate: Date | null;
+  voucherStatus: string | null;
+  totalGrossAmount: number | null;
+  totalNetAmount: number | null;
+  totalTaxAmount: number | null;
+  currency: string;
+  title: string | null;
+  lineItemsCount: number | null;
+  lineItemsJson: string | null;
+  lexwareContactId: string;
+  lexwareDeepLink: string;
+} {
+  const lineItems = detail.lineItems?.map((li) => ({
+    name: li.name,
+    quantity: li.quantity,
+    unitName: li.unitName,
+    unitPrice: li.unitPrice?.grossAmount,
+    amount: li.lineItemAmount,
+  }));
+
+  return {
+    voucherType,
+    voucherNumber: detail.voucherNumber || null,
+    voucherDate: detail.voucherDate ? new Date(detail.voucherDate) : null,
+    voucherStatus: detail.voucherStatus || null,
+    totalGrossAmount: detail.totalPrice?.totalGrossAmount ?? null,
+    totalNetAmount: detail.totalPrice?.totalNetAmount ?? null,
+    totalTaxAmount: detail.totalPrice?.totalTaxAmount ?? null,
+    currency: detail.totalPrice?.currency || 'EUR',
+    title: detail.title || null,
+    lineItemsCount: detail.lineItems?.length ?? null,
+    lineItemsJson: lineItems ? JSON.stringify(lineItems) : null,
+    lexwareContactId,
+    lexwareDeepLink: buildLexwareDeepLink(voucherType, detail.id),
+  };
+}
+
+// --------------------------------------------------------
+// Hilfsfunktionen
+// --------------------------------------------------------
+function getFirstEmail(lc: LexwareContact): string | undefined {
+  const emails = lc.emailAddresses;
+  if (!emails) return undefined;
+  return (
+    emails.business?.[0] ||
+    emails.office?.[0] ||
+    emails.private?.[0] ||
+    emails.other?.[0]
+  );
+}
+
+function getFirstPhone(lc: LexwareContact): string | undefined {
+  const phones = lc.phoneNumbers;
+  if (!phones) return undefined;
+  return (
+    phones.business?.[0] ||
+    phones.office?.[0] ||
+    phones.private?.[0] ||
+    phones.other?.[0]
+  );
+}
+
+// --------------------------------------------------------
+// Lexware VoucherList Item -> Voucher Type
+// --------------------------------------------------------
+export function voucherListItemToType(
+  item: LexwareVoucherListItem,
+): VoucherType {
+  return voucherTypeFromLexware(item.voucherType);
+}
--- a/packages/crm-service/src/lexware/utils/rate-limiter.ts
+++ b/packages/crm-service/src/lexware/utils/rate-limiter.ts
@ -0,0 +1,64 @@
+// ============================================================
+// Token Bucket Rate Limiter fuer Lexware Office API
+// ============================================================
+// Max 2 Requests/Sekunde (Lexware Limit)
+// ============================================================
+
+export class RateLimiter {
+  private tokens: number;
+  private lastRefill: number;
+  private readonly maxTokens: number;
+  private readonly refillRate: number; // Tokens pro Sekunde
+
+  constructor(maxTokens = 2, refillRate = 2) {
+    this.maxTokens = maxTokens;
+    this.refillRate = refillRate;
+    this.tokens = maxTokens;
+    this.lastRefill = Date.now();
+  }
+
+  /**
+   * Wartet bis ein Token verfuegbar ist, dann wird er verbraucht.
+   * Blockiert maximal 5 Sekunden.
+   */
+  async acquire(): Promise<void> {
+    this.refill();
+
+    if (this.tokens >= 1) {
+      this.tokens -= 1;
+      return;
+    }
+
+    // Berechne Wartezeit bis naechster Token verfuegbar
+    const deficit = 1 - this.tokens;
+    const waitMs = Math.ceil((deficit / this.refillRate) * 1000);
+
+    // Max 5 Sekunden warten
+    const clampedWait = Math.min(waitMs, 5000);
+    await new Promise((resolve) => setTimeout(resolve, clampedWait));
+
+    this.refill();
+    this.tokens = Math.max(0, this.tokens - 1);
+  }
+
+  /**
+   * Fuellt Tokens basierend auf vergangener Zeit auf.
+   */
+  private refill(): void {
+    const now = Date.now();
+    const elapsed = (now - this.lastRefill) / 1000;
+    this.tokens = Math.min(
+      this.maxTokens,
+      this.tokens + elapsed * this.refillRate,
+    );
+    this.lastRefill = now;
+  }
+
+  /**
+   * Aktuelle Token-Anzahl (fuer Monitoring).
+   */
+  getTokens(): number {
+    this.refill();
+    return this.tokens;
+  }
+}
--- a/packages/crm-service/src/redis/redis.service.ts
+++ b/packages/crm-service/src/redis/redis.service.ts
@ -76,4 +76,13 @@ export class RedisService implements OnModuleInit, OnModuleDestroy {
  async del(key: string): Promise<void> {
    await this.client.del(key);
  }
+
+  /**
+   * SET key NX EX ttl - Distributed Lock.
+   * Gibt true zurueck wenn Lock erworben, false wenn bereits gelockt.
+   */
+  async setNx(key: string, value: string, ttlSeconds: number): Promise<boolean> {
+    const result = await this.client.set(key, value, 'EX', ttlSeconds, 'NX');
+    return result === 'OK';
+  }
 }