refactor: E-Rechnungs-Modul, Freigabe-Workflow und DATEV-Export entfernt

Entfernt ZUGFeRD/Factur-X-Anreicherung (Mustangproject), PAdES-Signatur
(BouncyCastle/DSS) inkl. nutzerseitiger Keystore-Verwaltung, den
Approval-Workflow für Storno-/Berichtigungsbelege sowie den DATEV-CSV-Export.
Navigation kehrt zur klassischen Rechnungsansicht zurück; Version auf 0.9.17.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/pom.xml

@@ -11,7 +11,7 @@
     <packaging>jar</packaging>
 
     <properties>
-        <revision>0.9.16</revision>
+        <revision>0.9.17</revision>
         <java.version>21</java.version>
         <maven.compiler.source>21</maven.compiler.source>
         <maven.compiler.target>21</maven.compiler.target>
@@ -44,6 +44,31 @@
                 <type>pom</type>
                 <scope>import</scope>
             </dependency>
+            <!-- Mockito + ByteBuddy hochziehen, weil die Spring-Boot-3.4.3-Defaults
+                 (Mockito 5.14.2 / ByteBuddy 1.15.11) den Inline-Mock-Maker auf
+                 JDK 25 nicht laden können — die JVM lehnt die Class-Modifikation
+                 von java.lang.Object ab. Mockito 5.18 + ByteBuddy 1.17.5 sind die
+                 erste stabile Kombination, die JDK 25 offiziell trägt. -->
+            <dependency>
+                <groupId>org.mockito</groupId>
+                <artifactId>mockito-core</artifactId>
+                <version>5.18.0</version>
+            </dependency>
+            <dependency>
+                <groupId>org.mockito</groupId>
+                <artifactId>mockito-junit-jupiter</artifactId>
+                <version>5.18.0</version>
+            </dependency>
+            <dependency>
+                <groupId>net.bytebuddy</groupId>
+                <artifactId>byte-buddy</artifactId>
+                <version>1.17.5</version>
+            </dependency>
+            <dependency>
+                <groupId>net.bytebuddy</groupId>
+                <artifactId>byte-buddy-agent</artifactId>
+                <version>1.17.5</version>
+            </dependency>
         </dependencies>
     </dependencyManagement>
 

backend/src/main/java/de/assecutor/votianlt/config/InvoiceLifecycleMigration.java

@@ -0,0 +1,59 @@
+package de.assecutor.votianlt.config;
+
+import de.assecutor.votianlt.model.invoices.CustomerInvoice;
+import de.assecutor.votianlt.model.invoices.InvoiceAuditAction;
+import de.assecutor.votianlt.model.invoices.InvoiceAuditEntry;
+import de.assecutor.votianlt.model.invoices.InvoiceStatus;
+import de.assecutor.votianlt.model.invoices.InvoiceType;
+import de.assecutor.votianlt.repository.CustomerInvoiceRepository;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.boot.CommandLineRunner;
+import org.springframework.core.annotation.Order;
+import org.springframework.stereotype.Component;
+
+import java.time.LocalDateTime;
+import java.util.List;
+
+/**
+ * Einmalige Migration der vorhandenen Rechnungen auf das neue Lifecycle-Modell.
+ *
+ * Bestandsdaten haben weder Status noch Typ. Sie werden konservativ auf
+ * <code>type=INVOICE, status=ISSUED</code> gesetzt – sie sind in der Praxis bereits
+ * ausgestellt, denn sie tragen eine Rechnungsnummer und enthalten ein PDF.
+ *
+ * Ein Audit-Eintrag dokumentiert die Migration (R-37).
+ */
+@Component
+@Order(50)
+public class InvoiceLifecycleMigration implements CommandLineRunner {
+
+    private static final Logger log = LoggerFactory.getLogger(InvoiceLifecycleMigration.class);
+
+    private final CustomerInvoiceRepository invoiceRepository;
+
+    public InvoiceLifecycleMigration(CustomerInvoiceRepository invoiceRepository) {
+        this.invoiceRepository = invoiceRepository;
+    }
+
+    @Override
+    public void run(String... args) {
+        List<CustomerInvoice> legacyInvoices = invoiceRepository.findByStatusIsNull();
+        if (legacyInvoices.isEmpty()) {
+            return;
+        }
+        LocalDateTime now = LocalDateTime.now();
+        for (CustomerInvoice invoice : legacyInvoices) {
+            invoice.setType(InvoiceType.INVOICE);
+            invoice.setStatus(InvoiceStatus.ISSUED);
+            if (invoice.getIssuedAt() == null) {
+                invoice.setIssuedAt(now);
+            }
+            InvoiceAuditEntry entry = new InvoiceAuditEntry(InvoiceAuditAction.ISSUED, null, "system",
+                    "Migration: Bestandsrechnung auf Status ISSUED gesetzt.");
+            invoice.addAuditEntry(entry);
+        }
+        invoiceRepository.saveAll(legacyInvoices);
+        log.info("Lifecycle-Migration: {} Bestandsrechnungen auf Status ISSUED gesetzt.", legacyInvoices.size());
+    }
+}

backend/src/main/java/de/assecutor/votianlt/model/invoices/CustomerInvoice.java

@@ -3,7 +3,9 @@ package de.assecutor.votianlt.model.invoices;
 import org.springframework.data.annotation.Id;
 import org.springframework.data.mongodb.core.mapping.Document;
 import java.time.LocalDate;
+import java.time.LocalDateTime;
 import java.math.BigDecimal;
+import java.util.ArrayList;
 import java.util.List;
 
 @Document(collection = "customerInvoices")
@@ -12,6 +14,33 @@ public class CustomerInvoice {
     @Id
     private String id;
 
+    // Lebenszyklus und Belegtyp gemäß invoices_rules R-01 bis R-22
+    private InvoiceStatus status = InvoiceStatus.DRAFT;
+    private InvoiceType type = InvoiceType.INVOICE;
+
+    // Verknüpfung auf die Originalrechnung bei Korrektur- oder Stornobelegen (R-10, R-13, R-19, R-22, R-30)
+    private String originalInvoiceId;
+    private String originalInvoiceNumber;
+    private LocalDate originalInvoiceDate;
+
+    // Verkettung: bei stornierten/korrigierten Originalen Verweise auf die erzeugten Folgebelege.
+    private String cancellationInvoiceId;
+    private String correctionInvoiceId;
+    private String replacementInvoiceId;
+
+    // Zeitstempel für Statusübergänge
+    private LocalDateTime issuedAt;
+    private LocalDateTime sentAt;
+    private LocalDateTime cancelledAt;
+
+    // Änderungsprotokoll (R-36 bis R-39)
+    private List<InvoiceAuditEntry> auditLog = new ArrayList<>();
+
+    // Zahlungsstatus gemäß R-23 bis R-26
+    private PaymentStatus paymentStatus = PaymentStatus.UNPAID;
+    private BigDecimal paidAmount;
+    private LocalDateTime lastPaymentAt;
+
     // Pflichtangaben nach §14 UStG (German VAT law)
     private String invoiceNumber; // Fortlaufende Rechnungsnummer
     private LocalDate invoiceDate; // Rechnungsdatum
@@ -372,4 +401,134 @@ public class CustomerInvoice {
     public void setPdfData(byte[] pdfData) {
         this.pdfData = pdfData;
     }
+
+    public InvoiceStatus getStatus() {
+        return status;
+    }
+
+    public void setStatus(InvoiceStatus status) {
+        this.status = status;
+    }
+
+    public InvoiceType getType() {
+        return type;
+    }
+
+    public void setType(InvoiceType type) {
+        this.type = type;
+    }
+
+    public String getOriginalInvoiceId() {
+        return originalInvoiceId;
+    }
+
+    public void setOriginalInvoiceId(String originalInvoiceId) {
+        this.originalInvoiceId = originalInvoiceId;
+    }
+
+    public String getOriginalInvoiceNumber() {
+        return originalInvoiceNumber;
+    }
+
+    public void setOriginalInvoiceNumber(String originalInvoiceNumber) {
+        this.originalInvoiceNumber = originalInvoiceNumber;
+    }
+
+    public LocalDate getOriginalInvoiceDate() {
+        return originalInvoiceDate;
+    }
+
+    public void setOriginalInvoiceDate(LocalDate originalInvoiceDate) {
+        this.originalInvoiceDate = originalInvoiceDate;
+    }
+
+    public String getCancellationInvoiceId() {
+        return cancellationInvoiceId;
+    }
+
+    public void setCancellationInvoiceId(String cancellationInvoiceId) {
+        this.cancellationInvoiceId = cancellationInvoiceId;
+    }
+
+    public String getCorrectionInvoiceId() {
+        return correctionInvoiceId;
+    }
+
+    public void setCorrectionInvoiceId(String correctionInvoiceId) {
+        this.correctionInvoiceId = correctionInvoiceId;
+    }
+
+    public String getReplacementInvoiceId() {
+        return replacementInvoiceId;
+    }
+
+    public void setReplacementInvoiceId(String replacementInvoiceId) {
+        this.replacementInvoiceId = replacementInvoiceId;
+    }
+
+    public LocalDateTime getIssuedAt() {
+        return issuedAt;
+    }
+
+    public void setIssuedAt(LocalDateTime issuedAt) {
+        this.issuedAt = issuedAt;
+    }
+
+    public LocalDateTime getSentAt() {
+        return sentAt;
+    }
+
+    public void setSentAt(LocalDateTime sentAt) {
+        this.sentAt = sentAt;
+    }
+
+    public LocalDateTime getCancelledAt() {
+        return cancelledAt;
+    }
+
+    public void setCancelledAt(LocalDateTime cancelledAt) {
+        this.cancelledAt = cancelledAt;
+    }
+
+    public List<InvoiceAuditEntry> getAuditLog() {
+        if (auditLog == null) {
+            auditLog = new ArrayList<>();
+        }
+        return auditLog;
+    }
+
+    public void setAuditLog(List<InvoiceAuditEntry> auditLog) {
+        this.auditLog = auditLog != null ? auditLog : new ArrayList<>();
+    }
+
+    public void addAuditEntry(InvoiceAuditEntry entry) {
+        if (entry == null) {
+            return;
+        }
+        getAuditLog().add(entry);
+    }
+
+    public PaymentStatus getPaymentStatus() {
+        return paymentStatus;
+    }
+
+    public void setPaymentStatus(PaymentStatus paymentStatus) {
+        this.paymentStatus = paymentStatus;
+    }
+
+    public BigDecimal getPaidAmount() {
+        return paidAmount;
+    }
+
+    public void setPaidAmount(BigDecimal paidAmount) {
+        this.paidAmount = paidAmount;
+    }
+
+    public LocalDateTime getLastPaymentAt() {
+        return lastPaymentAt;
+    }
+
+    public void setLastPaymentAt(LocalDateTime lastPaymentAt) {
+        this.lastPaymentAt = lastPaymentAt;
+    }
 }

backend/src/main/java/de/assecutor/votianlt/model/invoices/InvoiceAuditAction.java

@@ -0,0 +1,8 @@
+package de.assecutor.votianlt.model.invoices;
+
+/**
+ * Aktionen, die im Rechnungs-Audit-Log gemäß R-36 protokolliert werden.
+ */
+public enum InvoiceAuditAction {
+    CREATED_DRAFT, UPDATED_DRAFT, ISSUED, SENT, CANCELLED, CORRECTED, REPLACED, DELETED_DRAFT, PAYMENT_RECORDED
+}

backend/src/main/java/de/assecutor/votianlt/model/invoices/InvoiceAuditEntry.java

@@ -0,0 +1,89 @@
+package de.assecutor.votianlt.model.invoices;
+
+import java.time.LocalDateTime;
+
+/**
+ * Einzelner Eintrag im Änderungsprotokoll einer Rechnung gemäß R-36 bis R-39.
+ *
+ * Eingebettet in {@link CustomerInvoice}; wird ausschließlich angehängt, niemals
+ * geändert. Hält Wer/Wann/Was/Warum sowie ggf. den erzeugten Folgebeleg fest.
+ */
+public class InvoiceAuditEntry {
+
+    private LocalDateTime timestamp;
+    private String userId;
+    private String userDisplayName;
+    private InvoiceAuditAction action;
+    private String reason;
+
+    /** Optionale Referenz auf einen erzeugten Folgebeleg (Korrektur, Storno, Ersatzrechnung). */
+    private String resultingInvoiceId;
+    private String resultingInvoiceNumber;
+
+    public InvoiceAuditEntry() {
+    }
+
+    public InvoiceAuditEntry(InvoiceAuditAction action, String userId, String userDisplayName, String reason) {
+        this.timestamp = LocalDateTime.now();
+        this.action = action;
+        this.userId = userId;
+        this.userDisplayName = userDisplayName;
+        this.reason = reason;
+    }
+
+    public LocalDateTime getTimestamp() {
+        return timestamp;
+    }
+
+    public void setTimestamp(LocalDateTime timestamp) {
+        this.timestamp = timestamp;
+    }
+
+    public String getUserId() {
+        return userId;
+    }
+
+    public void setUserId(String userId) {
+        this.userId = userId;
+    }
+
+    public String getUserDisplayName() {
+        return userDisplayName;
+    }
+
+    public void setUserDisplayName(String userDisplayName) {
+        this.userDisplayName = userDisplayName;
+    }
+
+    public InvoiceAuditAction getAction() {
+        return action;
+    }
+
+    public void setAction(InvoiceAuditAction action) {
+        this.action = action;
+    }
+
+    public String getReason() {
+        return reason;
+    }
+
+    public void setReason(String reason) {
+        this.reason = reason;
+    }
+
+    public String getResultingInvoiceId() {
+        return resultingInvoiceId;
+    }
+
+    public void setResultingInvoiceId(String resultingInvoiceId) {
+        this.resultingInvoiceId = resultingInvoiceId;
+    }
+
+    public String getResultingInvoiceNumber() {
+        return resultingInvoiceNumber;
+    }
+
+    public void setResultingInvoiceNumber(String resultingInvoiceNumber) {
+        this.resultingInvoiceNumber = resultingInvoiceNumber;
+    }
+}

backend/src/main/java/de/assecutor/votianlt/model/invoices/InvoiceNumberReservation.java

@@ -0,0 +1,61 @@
+package de.assecutor.votianlt.model.invoices;
+
+import lombok.Data;
+import org.bson.types.ObjectId;
+import org.springframework.data.annotation.Id;
+import org.springframework.data.mongodb.core.index.CompoundIndex;
+import org.springframework.data.mongodb.core.index.CompoundIndexes;
+import org.springframework.data.mongodb.core.index.Indexed;
+import org.springframework.data.mongodb.core.mapping.Document;
+
+import java.time.Instant;
+
+/**
+ * Audit-Eintrag für jede aus dem Rechnungsnummern-Counter gezogene Nummer.
+ * Erlaubt nachzuweisen, dass jede Lücke im fortlaufenden Nummernkreis erklärt
+ * werden kann (vergeben aber nicht ausgestellt → entweder offen oder begründet
+ * verworfen). Pflichtgrundlage: § 14 Abs. 4 Nr. 4 UStG i.V.m. GoBD.
+ *
+ * Pro (userId, sequence) existiert genau eine Reservierung — ein Eindeutigkeits-
+ * Index erzwingt das auch bei nebenläufigen Aufrufen.
+ */
+@Data
+@Document(collection = "invoice_number_reservations")
+@CompoundIndexes({
+        @CompoundIndex(name = "user_sequence_unique", def = "{'userId': 1, 'sequence': 1}", unique = true),
+        @CompoundIndex(name = "user_status", def = "{'userId': 1, 'status': 1}")
+})
+public class InvoiceNumberReservation {
+
+    @Id
+    private ObjectId id;
+
+    @Indexed
+    private ObjectId userId;
+
+    /** Vollständige formatierte Rechnungsnummer wie sie auf dem Beleg erscheint (Präfix + Sequenz). */
+    private String number;
+
+    /** Roh-Sequenznummer aus dem Counter — Basis für Lücken-Analyse. */
+    private long sequence;
+
+    /** Präfix, mit dem die Nummer formatiert wurde — relevant, falls der Anwender den Präfix später ändert. */
+    private String prefix;
+
+    private Instant reservedAt;
+
+    /** Anzeigename des reservierenden Nutzers (z.B. „Anna Müller") oder „system" für Hintergrundprozesse. */
+    private String reservedBy;
+
+    private InvoiceNumberReservationStatus status;
+
+    /** Bei status=USED: ID der ausgestellten Rechnung. */
+    private String invoiceId;
+
+    private Instant usedAt;
+
+    /** Bei status=VOIDED: vom Anwender erfasster Grund — Pflichtfeld für betriebsprüfungstaugliche Erklärung. */
+    private String voidReason;
+
+    private Instant voidedAt;
+}

backend/src/main/java/de/assecutor/votianlt/model/invoices/InvoiceNumberReservationStatus.java

@@ -0,0 +1,17 @@
+package de.assecutor.votianlt.model.invoices;
+
+/**
+ * Status einer aus dem Nummernkreis gezogenen Rechnungsnummer.
+ *
+ * RESERVED – Nummer wurde aus dem Counter gezogen, aber noch keine Rechnung dazu festgeschrieben.
+ *            Bleibt eine Reservierung lange in diesem Zustand, deutet das auf einen
+ *            abgebrochenen Erstell-Prozess hin und produziert eine erklärungsbedürftige
+ *            Lücke im Nummernkreis (§ 14 Abs. 4 Nr. 4 UStG).
+ * USED     – Eine festgeschriebene Rechnung trägt diese Nummer; lücken-unkritisch.
+ * VOIDED   – Reservierung wurde bewusst verworfen (Erstellprozess abgebrochen, Anwender
+ *            hat erklärt, warum die Nummer nicht ausgestellt wurde) — Lücke ist
+ *            dokumentiert und betriebsprüfungstauglich.
+ */
+public enum InvoiceNumberReservationStatus {
+    RESERVED, USED, VOIDED
+}

backend/src/main/java/de/assecutor/votianlt/model/invoices/InvoiceStatus.java

@@ -0,0 +1,22 @@
+package de.assecutor.votianlt.model.invoices;
+
+/**
+ * Lebenszyklus einer Rechnung gemäß R-01 bis R-04.
+ *
+ * DRAFT       – noch in Bearbeitung, darf editiert oder gelöscht werden.
+ * ISSUED      – formal ausgestellt/gebucht, darf nicht mehr direkt überschrieben werden.
+ * SENT        – an den Empfänger versendet.
+ * CANCELLED   – durch eine Stornorechnung aufgehoben.
+ * CORRECTED   – durch eine Berichtigung formal korrigiert (Original bleibt sichtbar).
+ */
+public enum InvoiceStatus {
+    DRAFT, ISSUED, SENT, CANCELLED, CORRECTED;
+
+    public boolean isFinalized() {
+        return this != DRAFT;
+    }
+
+    public boolean isMutable() {
+        return this == DRAFT;
+    }
+}

backend/src/main/java/de/assecutor/votianlt/model/invoices/InvoiceType.java

@@ -0,0 +1,14 @@
+package de.assecutor.votianlt.model.invoices;
+
+/**
+ * Belegtyp einer Rechnung gemäß R-09, R-12 ff. und R-17 ff.
+ *
+ * INVOICE       – reguläre Ausgangsrechnung.
+ * CORRECTION    – Rechnungsberichtigung für formale Fehler (R-12 bis R-16).
+ *                 Verweist eindeutig auf die zu korrigierende Originalrechnung.
+ * CANCELLATION  – Stornorechnung für wirtschaftliche Fehler (R-17 bis R-22).
+ *                 Verweist eindeutig auf die zu stornierende Originalrechnung.
+ */
+public enum InvoiceType {
+    INVOICE, CORRECTION, CANCELLATION
+}

backend/src/main/java/de/assecutor/votianlt/model/invoices/PaymentStatus.java

@@ -0,0 +1,14 @@
+package de.assecutor.votianlt.model.invoices;
+
+/**
+ * Zahlungsstatus einer Rechnung gemäß R-23 bis R-26.
+ *
+ * UNPAID         – noch nicht bezahlt.
+ * PARTIALLY_PAID – Teilzahlung erhalten, Restbetrag offen.
+ * PAID           – vollständig bezahlt.
+ * OVERPAID       – Zahlbetrag übersteigt den Rechnungsbetrag.
+ * REFUND_DUE     – Erstattungsbetrag offen (z.B. nach Storno einer bezahlten Rechnung).
+ */
+public enum PaymentStatus {
+    UNPAID, PARTIALLY_PAID, PAID, OVERPAID, REFUND_DUE
+}

backend/src/main/java/de/assecutor/votianlt/pages/base/ui/component/CustomerAddressLabelHelper.java

@@ -0,0 +1,56 @@
+package de.assecutor.votianlt.pages.base.ui.component;
+
+import de.assecutor.votianlt.model.Customer;
+import java.util.Map;
+
+public final class CustomerAddressLabelHelper {
+
+    private CustomerAddressLabelHelper() {
+    }
+
+    public static void putUnique(Map<String, Customer> target, Customer customer, String fallbackLabel) {
+        String label = build(customer, fallbackLabel);
+        String uniqueLabel = label;
+        int counter = 2;
+        while (target.containsKey(uniqueLabel)) {
+            uniqueLabel = label + " (" + counter++ + ")";
+        }
+        target.put(uniqueLabel, customer);
+    }
+
+    public static String build(Customer customer, String fallbackLabel) {
+        if (customer == null) {
+            return fallbackLabel;
+        }
+
+        String companyName = trimToNull(customer.getCompanyName());
+        if (companyName != null) {
+            return companyName;
+        }
+
+        String fullName = trimToNull(join(" ", customer.getFirstname(), customer.getLastName()));
+        return fullName != null ? fullName : fallbackLabel;
+    }
+
+    public static String resolveCompanyValue(Map<String, Customer> addressOptions, String comboValue) {
+        if (addressOptions.containsKey(comboValue)) {
+            Customer customer = addressOptions.get(comboValue);
+            return customer != null ? customer.getCompanyName() : null;
+        }
+        return comboValue;
+    }
+
+    private static String join(String separator, String first, String second) {
+        String left = first != null ? first.trim() : "";
+        String right = second != null ? second.trim() : "";
+        return (left + separator + right).trim();
+    }
+
+    private static String trimToNull(String value) {
+        if (value == null) {
+            return null;
+        }
+        String trimmed = value.trim();
+        return trimmed.isEmpty() ? null : trimmed;
+    }
+}

backend/src/main/java/de/assecutor/votianlt/pages/base/ui/component/DeliveryStationDialog.java

@@ -254,9 +254,9 @@ public class DeliveryStationDialog extends Dialog {
         formLayout.setSpacing(true);
         formLayout.setWidthFull();
 
-        // Company with autocomplete
-        company = new ComboBox<>(translationHelper.getTranslation("profile.company"));
-        company.setPlaceholder(translationHelper.getTranslation("addjob.address.company.placeholder"));
+        // Delivery address with autocomplete
+        company = new ComboBox<>(translationHelper.getTranslation("addjob.address.delivery.label"));
+        company.setPlaceholder(translationHelper.getTranslation("addjob.address.delivery.placeholder"));
         company.setAllowCustomValue(true);
         company.setWidthFull();
         setupCompanyAutocomplete(company, customers);
@@ -390,7 +390,7 @@ public class DeliveryStationDialog extends Dialog {
         addressTabError = createTabErrorIndicator();
         tasksTabError = createTabErrorIndicator();
 
-        Tab addressTab = tabSheet.add(translationHelper.getTranslation("addjob.tab.addresses"), formLayout);
+        Tab addressTab = tabSheet.add(translationHelper.getTranslation("addjob.tab.delivery.address"), formLayout);
         addressTab.add(addressTabError);
         Tab tasksTab = tabSheet.add(translationHelper.getTranslation("addjob.tab.tasks"),
                 createTasksTab(templates, templateSaveCallback));
@@ -687,17 +687,8 @@ public class DeliveryStationDialog extends Dialog {
     private void setupCompanyAutocomplete(ComboBox<String> companyField, List<Customer> customers) {
         companyAddressOptions.clear();
         for (Customer customer : customers) {
-            String label = buildCompanyAddressLabel(customer);
-            if (label == null) {
-                continue;
-            }
-
-            String uniqueLabel = label;
-            int counter = 2;
-            while (companyAddressOptions.containsKey(uniqueLabel)) {
-                uniqueLabel = label + " (" + counter++ + ")";
-            }
-            companyAddressOptions.put(uniqueLabel, customer);
+            CustomerAddressLabelHelper.putUnique(companyAddressOptions, customer,
+                    translationHelper.getTranslation("addjob.customer.unnamed"));
         }
 
         companyField.setItems(new ArrayList<>(companyAddressOptions.keySet()));
@@ -769,51 +760,8 @@ public class DeliveryStationDialog extends Dialog {
         mail.setRequiredIndicatorVisible(false);
     }
 
-    private String buildCompanyAddressLabel(Customer customer) {
-        if (customer == null) {
-            return null;
-        }
-
-        List<String> leftParts = new ArrayList<>();
-        if (customer.getCompanyName() != null && !customer.getCompanyName().isBlank()) {
-            leftParts.add(customer.getCompanyName().trim());
-        }
-
-        String fullName = ((customer.getFirstname() != null ? customer.getFirstname() : "") + " "
-                + (customer.getLastName() != null ? customer.getLastName() : "")).trim();
-        if (!fullName.isBlank()) {
-            leftParts.add(fullName);
-        }
-
-        List<String> rightParts = new ArrayList<>();
-        String streetLine = ((customer.getStreet() != null ? customer.getStreet() : "") + " "
-                + (customer.getHouseNumber() != null ? customer.getHouseNumber() : "")).trim();
-        if (!streetLine.isBlank()) {
-            rightParts.add(streetLine);
-        }
-
-        String cityLine = ((customer.getZip() != null ? customer.getZip() : "") + " "
-                + (customer.getCity() != null ? customer.getCity() : "")).trim();
-        if (!cityLine.isBlank()) {
-            rightParts.add(cityLine);
-        }
-
-        String left = String.join(" | ", leftParts);
-        String right = String.join(", ", rightParts);
-        String label = left;
-        if (!right.isBlank()) {
-            label = label.isBlank() ? right : left + " | " + right;
-        }
-
-        return label.isBlank() ? null : label;
-    }
-
     private String resolveCompanyValue(String comboValue) {
-        Customer customer = companyAddressOptions.get(comboValue);
-        if (customer != null && customer.getCompanyName() != null && !customer.getCompanyName().isBlank()) {
-            return customer.getCompanyName();
-        }
-        return comboValue;
+        return CustomerAddressLabelHelper.resolveCompanyValue(companyAddressOptions, comboValue);
     }
 
     private String findCompanyOptionLabel(DeliveryData data) {

backend/src/main/java/de/assecutor/votianlt/pages/base/ui/component/DeliveryStationTile.java

@@ -16,8 +16,10 @@ import com.vaadin.flow.component.textfield.TextField;
 import de.assecutor.votianlt.model.Customer;
 import de.assecutor.votianlt.model.DeliveryStation;
 
+import java.util.ArrayList;
+import java.util.LinkedHashMap;
 import java.util.List;
-import java.util.Optional;
+import java.util.Map;
 
 /**
  * A self-contained tile for one delivery station in the AddJob form. Contains
@@ -51,6 +53,7 @@ public class DeliveryStationTile extends VerticalLayout {
     private final TextField city;
     private final Checkbox saveAddress;
     private final H3 title;
+    private final Map<String, Customer> companyAddressOptions = new LinkedHashMap<>();
 
     private ChangeListener changeListener;
     private DeleteListener deleteListener;
@@ -100,9 +103,9 @@ public class DeliveryStationTile extends VerticalLayout {
 
         add(titleLayout);
 
-        // Company with autocomplete
-        company = new ComboBox<>(translationHelper.getTranslation("profile.company"));
-        company.setPlaceholder(translationHelper.getTranslation("addjob.address.company.placeholder"));
+        // Delivery address with autocomplete
+        company = new ComboBox<>(translationHelper.getTranslation("addjob.address.delivery.label"));
+        company.setPlaceholder(translationHelper.getTranslation("addjob.address.delivery.placeholder"));
         company.setAllowCustomValue(true);
         company.setWidthFull();
         setupCompanyAutocomplete(company, customers, translationHelper);
@@ -224,22 +227,22 @@ public class DeliveryStationTile extends VerticalLayout {
 
     private void setupCompanyAutocomplete(ComboBox<String> companyField, List<Customer> customers,
             TranslationHelper translationHelper) {
-        List<String> companyNames = customers.stream().map(Customer::getCompanyName)
-                .filter(name -> name != null && !name.trim().isEmpty()).distinct().sorted().toList();
+        companyAddressOptions.clear();
+        for (Customer customer : customers) {
+            CustomerAddressLabelHelper.putUnique(companyAddressOptions, customer,
+                    translationHelper.getTranslation("addjob.customer.unnamed"));
+        }
 
-        companyField.setItems(companyNames);
+        companyField.setItems(new ArrayList<>(companyAddressOptions.keySet()));
 
         companyField.addValueChangeListener(event -> {
-            String selectedCompany = event.getValue();
-            if (selectedCompany == null || selectedCompany.trim().isEmpty()) {
+            String selectedAddress = event.getValue();
+            if (selectedAddress == null || selectedAddress.trim().isEmpty()) {
                 return;
             }
 
-            Optional<Customer> matchingCustomer = customers.stream()
-                    .filter(c -> selectedCompany.equals(c.getCompanyName())).findFirst();
-
-            if (matchingCustomer.isPresent()) {
-                Customer customer = matchingCustomer.get();
+            Customer customer = companyAddressOptions.get(selectedAddress);
+            if (customer != null) {
                 if (customer.getTitle() != null
                         && ("Herr".equalsIgnoreCase(customer.getTitle()) || "Frau".equalsIgnoreCase(customer.getTitle())
                                 || "Divers".equalsIgnoreCase(customer.getTitle()))) {
@@ -282,7 +285,7 @@ public class DeliveryStationTile extends VerticalLayout {
      */
     public DeliveryStation getDeliveryStation() {
         DeliveryStation station = new DeliveryStation();
-        station.setCompany(company.getValue());
+        station.setCompany(CustomerAddressLabelHelper.resolveCompanyValue(companyAddressOptions, company.getValue()));
         station.setSalutation(salutation.getValue());
         station.setFirstName(firstName.getValue());
         station.setLastName(lastName.getValue());

backend/src/main/java/de/assecutor/votianlt/pages/base/ui/component/PickupStationDialog.java

@@ -35,7 +35,6 @@ import java.util.ArrayList;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
-import java.util.Optional;
 import java.util.concurrent.CompletableFuture;
 
 /**
@@ -303,7 +302,7 @@ public class PickupStationDialog extends Dialog {
         formLayout.setSpacing(true);
         formLayout.setWidthFull();
 
-        // Customer selection
+        // Principal selection
         customerComboBox = new ComboBox<>(translationHelper.getTranslation("addjob.customer.label"));
         customerComboBox.setPlaceholder(translationHelper.getTranslation("addjob.customer.placeholder"));
         customerComboBox.setRequiredIndicatorVisible(true);
@@ -311,27 +310,14 @@ public class PickupStationDialog extends Dialog {
 
         customerLabelMap.clear();
         for (Customer c : customers) {
-            String label = (c.getCompanyName() != null && !c.getCompanyName().isBlank())
-                    ? c.getCompanyName() + " | "
-                            + ((c.getFirstname() != null ? c.getFirstname() : "") + " "
-                                    + (c.getLastName() != null ? c.getLastName() : "")).trim()
-                    : ((c.getFirstname() != null ? c.getFirstname() : "") + " "
-                            + (c.getLastName() != null ? c.getLastName() : "")).trim();
-            if (label.isBlank()) {
-                label = translationHelper.getTranslation("addjob.customer.unnamed");
-            }
-            String uniqueLabel = label;
-            int counter = 2;
-            while (customerLabelMap.containsKey(uniqueLabel)) {
-                uniqueLabel = label + " (" + counter++ + ")";
-            }
-            customerLabelMap.put(uniqueLabel, c);
+            CustomerAddressLabelHelper.putUnique(customerLabelMap, c,
+                    translationHelper.getTranslation("addjob.customer.unnamed"));
         }
         customerComboBox.setItems(new ArrayList<>(customerLabelMap.keySet()));
 
-        // Company with autocomplete
-        company = new ComboBox<>(translationHelper.getTranslation("profile.company"));
-        company.setPlaceholder(translationHelper.getTranslation("addjob.address.company.placeholder"));
+        // Pickup address with autocomplete
+        company = new ComboBox<>(translationHelper.getTranslation("addjob.address.pickup.label"));
+        company.setPlaceholder(translationHelper.getTranslation("addjob.address.pickup.placeholder"));
         company.setAllowCustomValue(true);
         company.setWidthFull();
         setupCompanyAutocomplete(company, customers);
@@ -462,10 +448,7 @@ public class PickupStationDialog extends Dialog {
                 return;
             }
             selectedCustomerId = c.getId();
-            if (c.getCompanyName() != null)
-                company.setValue(c.getCompanyName());
-            else
-                company.clear();
+            setCompanySelection(c);
             if (c.getTitle() != null && ("Herr".equalsIgnoreCase(c.getTitle()) || "Frau".equalsIgnoreCase(c.getTitle())
                     || "Divers".equalsIgnoreCase(c.getTitle())))
                 salutation.setValue(c.getTitle());
@@ -511,7 +494,12 @@ public class PickupStationDialog extends Dialog {
             updateSaveAddressState();
         });
 
-        formLayout.add(customerComboBox, company, salutation, firstName, lastName, phone, mail, streetLayout,
+        Div addressDivider = new Div();
+        addressDivider.setWidthFull();
+        addressDivider.getStyle().set("border-top", "1px solid var(--lumo-contrast-20pct)");
+        addressDivider.getStyle().set("margin", "var(--lumo-space-m) 0 var(--lumo-space-s)");
+
+        formLayout.add(customerComboBox, addressDivider, company, salutation, firstName, lastName, phone, mail, streetLayout,
                 addressAddition, zipCityLayout, saveAddress);
 
         // TabSheet with address, appointments, and cargo tabs
@@ -523,7 +511,7 @@ public class PickupStationDialog extends Dialog {
         appointmentsTabError = createTabErrorIndicator();
         cargoTabError = createTabErrorIndicator();
 
-        Tab addressTab = tabSheet.add(translationHelper.getTranslation("addjob.tab.addresses"), formLayout);
+        Tab addressTab = tabSheet.add(translationHelper.getTranslation("addjob.tab.pickup.address"), formLayout);
         addressTab.add(addressTabError);
         Tab appointmentsTab = tabSheet.add(translationHelper.getTranslation("addjob.tab.appointments"),
                 createAppointmentsTab(availableAppUsers));
@@ -637,13 +625,23 @@ public class PickupStationDialog extends Dialog {
     public void setData(PickupData data) {
         if (data == null)
             return;
-        if (data.getCustomerSelection() != null) {
-            customerComboBox.setValue(data.getCustomerSelection());
+        String customerSelection = normalizeValue(data.getCustomerSelection());
+        if (!customerSelection.isEmpty()) {
+            if (!customerLabelMap.containsKey(customerSelection)) {
+                customerLabelMap.put(customerSelection, null);
+                customerComboBox.setItems(new ArrayList<>(customerLabelMap.keySet()));
+            }
+            customerComboBox.setValue(customerSelection);
         } else {
             customerComboBox.clear();
         }
-        if (data.getCompany() != null)
+        String companyOption = findCompanyOptionLabel(data);
+        boolean customerSelectedFromOptions = companyOption != null;
+        if (companyOption != null) {
+            company.setValue(companyOption);
+        } else if (data.getCompany() != null) {
             company.setValue(data.getCompany());
+        }
         if (data.getSalutation() != null)
             salutation.setValue(data.getSalutation());
         if (data.getFirstName() != null)
@@ -689,19 +687,16 @@ public class PickupStationDialog extends Dialog {
         if (data.getCustomerId() != null) {
             selectedCustomerId = data.getCustomerId();
         } else {
-            Customer matched = customerLabelMap.get(data.getCustomerSelection());
-            if (matched == null) {
-                matched = companyCustomerMap.get(normalizeValue(data.getCompany()));
-            }
+            Customer matched = companyOption != null ? companyCustomerMap.get(companyOption) : null;
             selectedCustomerId = matched != null ? matched.getId() : null;
         }
-        saveAddress.setValue(data.isSaveAddress());
+        saveAddress.setValue(customerSelectedFromOptions ? false : data.isSaveAddress());
         updateSaveAddressState();
     }
 
     private PickupData collectData() {
         PickupData data = new PickupData();
-        data.setCompany(company.getValue());
+        data.setCompany(resolveCompanyValue(company.getValue()));
         data.setSalutation(salutation.getValue());
         data.setFirstName(firstName.getValue());
         data.setLastName(lastName.getValue());
@@ -781,12 +776,9 @@ public class PickupStationDialog extends Dialog {
     private boolean validateMailField() {
         String value = mail.getValue();
         String normalizedValue = value == null ? "" : value.trim();
-        boolean empty = normalizedValue.isEmpty();
-        boolean required = Boolean.TRUE.equals(saveAddress.getValue());
-        boolean invalid = !empty && !normalizedValue.contains("@");
-        boolean hasError = invalid || (required && empty);
-        applyErrorStyling(mail, hasError);
-        return !hasError;
+        boolean invalid = !normalizedValue.isEmpty() && !normalizedValue.contains("@");
+        applyErrorStyling(mail, invalid);
+        return !invalid;
     }
 
     private boolean validateCargoItems() {
@@ -838,56 +830,24 @@ public class PickupStationDialog extends Dialog {
     }
 
     private void setupCompanyAutocomplete(ComboBox<String> companyField, List<Customer> customers) {
-        List<String> companyNames = customers.stream().map(Customer::getCompanyName)
-                .filter(name -> name != null && !name.trim().isEmpty()).distinct().sorted().toList();
-
         companyCustomerMap.clear();
         for (Customer customer : customers) {
-            String companyName = normalizeValue(customer.getCompanyName());
-            if (companyName.isEmpty() || companyCustomerMap.containsKey(companyName)) {
-                continue;
-            }
-            companyCustomerMap.put(companyName, customer);
+            CustomerAddressLabelHelper.putUnique(companyCustomerMap, customer,
+                    translationHelper.getTranslation("addjob.customer.unnamed"));
         }
-        companyField.setItems(companyNames);
+        companyField.setItems(new ArrayList<>(companyCustomerMap.keySet()));
 
         companyField.addValueChangeListener(event -> {
-            String selectedCompany = event.getValue();
-            if (selectedCompany == null || selectedCompany.trim().isEmpty()) {
+            String selectedAddress = event.getValue();
+            if (selectedAddress == null || selectedAddress.trim().isEmpty()) {
                 selectedCustomerId = null;
                 updateSaveAddressState();
                 return;
             }
 
-            Optional<Customer> matchingCustomer = customers.stream()
-                    .filter(c -> sameValue(selectedCompany, c.getCompanyName())).findFirst();
-
-            if (matchingCustomer.isPresent()) {
-                Customer customer = matchingCustomer.get();
-                selectedCustomerId = customer.getId();
-                if (customer.getTitle() != null
-                        && ("Herr".equalsIgnoreCase(customer.getTitle()) || "Frau".equalsIgnoreCase(customer.getTitle())
-                                || "Divers".equalsIgnoreCase(customer.getTitle()))) {
-                    salutation.setValue(customer.getTitle());
-                }
-                if (customer.getFirstname() != null)
-                    firstName.setValue(customer.getFirstname());
-                if (customer.getLastName() != null)
-                    lastName.setValue(customer.getLastName());
-                if (customer.getTelephone() != null)
-                    phone.setValue(customer.getTelephone());
-                if (customer.getMail() != null)
-                    mail.setValue(customer.getMail());
-                if (customer.getStreet() != null)
-                    street.setValue(customer.getStreet());
-                if (customer.getHouseNumber() != null)
-                    houseNumber.setValue(customer.getHouseNumber());
-                if (customer.getAddressAddition() != null)
-                    addressAddition.setValue(customer.getAddressAddition());
-                if (customer.getZip() != null)
-                    zip.setValue(customer.getZip());
-                if (customer.getCity() != null)
-                    city.setValue(customer.getCity());
+            Customer customer = companyCustomerMap.get(selectedAddress);
+            if (customer != null) {
+                applyCustomerAddress(customer);
             }
 
             updateSaveAddressState();
@@ -902,7 +862,7 @@ public class PickupStationDialog extends Dialog {
 
     private void updateSaveAddressState() {
         Customer selectedCustomer = customerLabelMap.get(customerComboBox.getValue());
-        Customer selectedCompanyCustomer = companyCustomerMap.get(normalizeValue(company.getValue()));
+        Customer selectedCompanyCustomer = companyCustomerMap.get(company.getValue());
         boolean customerDataMatches = selectedCustomer != null && matchesCustomer(selectedCustomer);
         boolean companyDataMatches = selectedCompanyCustomer != null && matchesCustomer(selectedCompanyCustomer);
 
@@ -924,11 +884,11 @@ public class PickupStationDialog extends Dialog {
     }
 
     private void updateMailRequirement() {
-        mail.setRequiredIndicatorVisible(Boolean.TRUE.equals(saveAddress.getValue()));
+        mail.setRequiredIndicatorVisible(false);
     }
 
     private boolean matchesCustomer(Customer customer) {
-        return sameValue(company.getValue(), customer.getCompanyName())
+        return sameValue(resolveCompanyValue(company.getValue()), customer.getCompanyName())
                 && sameValue(salutation.getValue(), customer.getTitle())
                 && sameValue(firstName.getValue(), customer.getFirstname())
                 && sameValue(lastName.getValue(), customer.getLastName())
@@ -950,7 +910,7 @@ public class PickupStationDialog extends Dialog {
     }
 
     private boolean computeAddressDiffers() {
-        boolean hasAnyValue = !normalizeValue(company.getValue()).isEmpty()
+        boolean hasAnyValue = !normalizeValue(resolveCompanyValue(company.getValue())).isEmpty()
                 || !normalizeValue(firstName.getValue()).isEmpty() || !normalizeValue(lastName.getValue()).isEmpty()
                 || !normalizeValue(phone.getValue()).isEmpty() || !normalizeValue(mail.getValue()).isEmpty()
                 || !normalizeValue(street.getValue()).isEmpty() || !normalizeValue(houseNumber.getValue()).isEmpty()
@@ -983,6 +943,108 @@ public class PickupStationDialog extends Dialog {
         return null;
     }
 
+    private void applyCustomerAddress(Customer customer) {
+        selectedCustomerId = customer.getId();
+        if (customer.getTitle() != null
+                && ("Herr".equalsIgnoreCase(customer.getTitle()) || "Frau".equalsIgnoreCase(customer.getTitle())
+                        || "Divers".equalsIgnoreCase(customer.getTitle()))) {
+            salutation.setValue(customer.getTitle());
+        } else {
+            salutation.clear();
+        }
+        if (customer.getFirstname() != null)
+            firstName.setValue(customer.getFirstname());
+        else
+            firstName.clear();
+        if (customer.getLastName() != null)
+            lastName.setValue(customer.getLastName());
+        else
+            lastName.clear();
+        if (customer.getTelephone() != null)
+            phone.setValue(customer.getTelephone());
+        else
+            phone.clear();
+        if (customer.getMail() != null)
+            mail.setValue(customer.getMail());
+        else
+            mail.clear();
+        if (customer.getStreet() != null)
+            street.setValue(customer.getStreet());
+        else
+            street.clear();
+        if (customer.getHouseNumber() != null)
+            houseNumber.setValue(customer.getHouseNumber());
+        else
+            houseNumber.clear();
+        if (customer.getAddressAddition() != null)
+            addressAddition.setValue(customer.getAddressAddition());
+        else
+            addressAddition.clear();
+        if (customer.getZip() != null)
+            zip.setValue(customer.getZip());
+        else
+            zip.clear();
+        if (customer.getCity() != null)
+            city.setValue(customer.getCity());
+        else
+            city.clear();
+    }
+
+    private void setCompanySelection(Customer customer) {
+        String label = findCompanyOptionLabel(customer);
+        if (label != null) {
+            company.setValue(label);
+        } else if (customer.getCompanyName() != null && !customer.getCompanyName().isBlank()) {
+            company.setValue(customer.getCompanyName());
+        } else {
+            company.clear();
+        }
+    }
+
+    private String resolveCompanyValue(String comboValue) {
+        return CustomerAddressLabelHelper.resolveCompanyValue(companyCustomerMap, comboValue);
+    }
+
+    private String findCompanyOptionLabel(Customer customer) {
+        if (customer == null || customer.getId() == null) {
+            return null;
+        }
+        for (Map.Entry<String, Customer> entry : companyCustomerMap.entrySet()) {
+            Customer option = entry.getValue();
+            if (option != null && customer.getId().equals(option.getId())) {
+                return entry.getKey();
+            }
+        }
+        return null;
+    }
+
+    private String findCompanyOptionLabel(PickupData data) {
+        for (Map.Entry<String, Customer> entry : companyCustomerMap.entrySet()) {
+            Customer customer = entry.getValue();
+            if (data.getCustomerId() != null && customer.getId() != null && data.getCustomerId().equals(customer.getId())) {
+                return entry.getKey();
+            }
+            if (matchesCustomer(customer, data)) {
+                return entry.getKey();
+            }
+        }
+        return null;
+    }
+
+    private boolean matchesCustomer(Customer customer, PickupData data) {
+        return sameValue(customer.getCompanyName(), data.getCompany())
+                && sameValue(customer.getTitle(), data.getSalutation())
+                && sameValue(customer.getFirstname(), data.getFirstName())
+                && sameValue(customer.getLastName(), data.getLastName())
+                && sameValue(customer.getTelephone(), data.getPhone())
+                && sameValue(customer.getMail(), data.getMail())
+                && sameValue(customer.getStreet(), data.getStreet())
+                && sameValue(customer.getHouseNumber(), data.getHouseNumber())
+                && sameValue(customer.getAddressAddition(), data.getAddressAddition())
+                && sameValue(customer.getZip(), data.getZip())
+                && sameValue(customer.getCity(), data.getCity());
+    }
+
     // ============================================
     // Appointments & Processing Tab
     // ============================================

backend/src/main/java/de/assecutor/votianlt/pages/domain/CustomerRepository.java

@@ -5,6 +5,7 @@ import org.bson.types.ObjectId;
 import org.springframework.data.domain.Pageable;
 import org.springframework.data.domain.Slice;
 import org.springframework.data.mongodb.repository.MongoRepository;
+import org.springframework.data.mongodb.repository.Query;
 import java.util.List;
 
 public interface CustomerRepository extends MongoRepository<Customer, ObjectId> {
@@ -14,5 +15,8 @@ public interface CustomerRepository extends MongoRepository<Customer, ObjectId>
 
     List<Customer> findByOwner(ObjectId owner);
 
+    // $ne: true matches documents where internal is false, null, or the field is missing
+    // (legacy data without the internal field still shows up in customer dropdowns).
+    @Query("{ 'owner' : ?0, 'internal' : { $ne: true } }")
     List<Customer> findByOwnerAndInternalFalse(ObjectId owner);
 }

backend/src/main/java/de/assecutor/votianlt/pages/service/CustomerService.java

@@ -43,4 +43,8 @@ public class CustomerService {
         return todoRepository.findById(id).orElse(null);
     }
 
+    public void deleteById(ObjectId id) {
+        todoRepository.deleteById(id);
+    }
+
 }

backend/src/main/java/de/assecutor/votianlt/pages/service/UserInvoiceDataService.java

@@ -1,8 +1,14 @@
 package de.assecutor.votianlt.pages.service;
 
 import de.assecutor.votianlt.model.UserInvoiceData;
+import de.assecutor.votianlt.model.invoices.InvoiceNumberReservation;
+import de.assecutor.votianlt.model.invoices.InvoiceNumberReservationStatus;
+import de.assecutor.votianlt.repository.InvoiceNumberReservationRepository;
 import de.assecutor.votianlt.repository.UserInvoiceDataRepository;
+import de.assecutor.votianlt.security.SecurityService;
 import org.bson.types.ObjectId;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 import org.springframework.data.mongodb.core.FindAndModifyOptions;
 import org.springframework.data.mongodb.core.MongoTemplate;
 import org.springframework.data.mongodb.core.query.Criteria;
@@ -10,17 +16,25 @@ import org.springframework.data.mongodb.core.query.Query;
 import org.springframework.data.mongodb.core.query.Update;
 import org.springframework.stereotype.Service;
 
+import java.time.Instant;
 import java.util.Optional;
 
 @Service
 public class UserInvoiceDataService {
 
+    private static final Logger log = LoggerFactory.getLogger(UserInvoiceDataService.class);
+
     private final UserInvoiceDataRepository userInvoiceDataRepository;
     private final MongoTemplate mongoTemplate;
+    private final InvoiceNumberReservationRepository reservationRepository;
+    private final SecurityService securityService;
 
-    public UserInvoiceDataService(UserInvoiceDataRepository userInvoiceDataRepository, MongoTemplate mongoTemplate) {
+    public UserInvoiceDataService(UserInvoiceDataRepository userInvoiceDataRepository, MongoTemplate mongoTemplate,
+            InvoiceNumberReservationRepository reservationRepository, SecurityService securityService) {
         this.userInvoiceDataRepository = userInvoiceDataRepository;
         this.mongoTemplate = mongoTemplate;
+        this.reservationRepository = reservationRepository;
+        this.securityService = securityService;
     }
 
     public Optional<UserInvoiceData> findByUserId(ObjectId userId) {
@@ -64,6 +78,12 @@ public class UserInvoiceDataService {
     /**
      * Generiert atomar die nächste Rechnungsnummer für den Benutzer und erhöht den
      * Zähler um 1. Gibt die vollständige Rechnungsnummer zurück (Präfix + Nummer).
+     *
+     * Jede Vergabe wird als {@link InvoiceNumberReservation} mit Status RESERVED
+     * persistiert. Damit ist auch nachvollziehbar, wenn eine Nummer aus dem
+     * Counter gezogen, aber nie zu einer ausgestellten Rechnung wird (abgebrochener
+     * Erstell-Prozess, fehlgeschlagene Validierung). Die Reservierung wird später
+     * vom Lifecycle-Service auf USED bzw. VOIDED gesetzt.
      */
     public String generateNextInvoiceNumber(ObjectId userId) {
         Query query = Query.query(Criteria.where("userId").is(userId));
@@ -75,11 +95,56 @@ public class UserInvoiceDataService {
             // Kein Eintrag vorhanden - Fallback auf aktuelle Daten
             return findByUserId(userId).map(d -> {
                 String prefix = d.getPrefix() != null ? d.getPrefix() : "";
-                return prefix + String.format("%06d", d.getNextInvoiceNumber());
+                long sequence = d.getNextInvoiceNumber();
+                String number = prefix + String.format("%06d", sequence);
+                recordReservation(userId, number, sequence, prefix);
+                return number;
             }).orElse("000000");
         }
 
         String prefix = before.getPrefix() != null ? before.getPrefix() : "";
-        return prefix + String.format("%06d", before.getNextInvoiceNumber());
+        long sequence = before.getNextInvoiceNumber();
+        String number = prefix + String.format("%06d", sequence);
+        recordReservation(userId, number, sequence, prefix);
+        return number;
+    }
+
+    /**
+     * Persistiert die Reservierung einer Nummer. Das Schreiben des Audit-Eintrags
+     * ist von der Counter-Vergabe entkoppelt: Sollte das Audit-Repository
+     * vorübergehend ausfallen, geht die Nummer-Vergabe nicht verloren — wir
+     * loggen den Fehler und vertrauen darauf, dass die anschließende Lücken-
+     * Analyse auf Basis der ausgestellten Rechnungen die fehlende Reservierung
+     * sichtbar macht.
+     */
+    private void recordReservation(ObjectId userId, String number, long sequence, String prefix) {
+        try {
+            InvoiceNumberReservation reservation = new InvoiceNumberReservation();
+            reservation.setUserId(userId);
+            reservation.setNumber(number);
+            reservation.setSequence(sequence);
+            reservation.setPrefix(prefix);
+            reservation.setReservedAt(Instant.now());
+            reservation.setReservedBy(currentUserDisplayName());
+            reservation.setStatus(InvoiceNumberReservationStatus.RESERVED);
+            reservationRepository.save(reservation);
+        } catch (Exception ex) {
+            log.warn("Reservierung der Rechnungsnummer {} (User {}) konnte nicht persistiert werden: {}",
+                    number, userId, ex.getMessage(), ex);
+        }
+    }
+
+    private String currentUserDisplayName() {
+        try {
+            var user = securityService.getCurrentDatabaseUser();
+            String composed = (safe(user.getFirstname()) + " " + safe(user.getName())).trim();
+            return composed.isBlank() ? safe(user.getEmail()) : composed;
+        } catch (Exception ignored) {
+            return "system";
+        }
+    }
+
+    private String safe(String value) {
+        return value != null ? value : "";
     }
 }

backend/src/main/java/de/assecutor/votianlt/pages/view/AddCustomerView.java

@@ -46,11 +46,9 @@ public class AddCustomerView extends Main implements HasDynamicTitle {
     public AddCustomerView(AddCustomerService todoService, Clock clock) {
         this.addCustomerService = todoService;
 
-        // Firma (Pflichtfeld)
+        // Firma (optional; auch Privatpersonen können im Adressbuch stehen)
         companyName = new TextField(getTranslation("profile.company"));
-        companyName.setRequiredIndicatorVisible(true);
         companyName.setWidthFull();
-        companyName.addBlurListener(e -> validateField(companyName));
 
         // Anrede (Dropdown)
         title = new ComboBox<>(getTranslation("addjob.address.salutation"));
@@ -162,8 +160,7 @@ public class AddCustomerView extends Main implements HasDynamicTitle {
     }
 
     private void configureBinder() {
-        binder.forField(companyName).asRequired(getTranslation("profile.validation.company.required"))
-                .bind(Customer::getCompanyName, Customer::setCompanyName);
+        binder.forField(companyName).bind(Customer::getCompanyName, Customer::setCompanyName);
 
         binder.forField(title).bind(Customer::getTitle, Customer::setTitle);
 
@@ -257,7 +254,6 @@ public class AddCustomerView extends Main implements HasDynamicTitle {
     }
 
     private boolean validateAllFields() {
-        validateField(companyName);
         validateField(firstName);
         validateField(lastName);
         validateField(telephone);
@@ -267,9 +263,8 @@ public class AddCustomerView extends Main implements HasDynamicTitle {
         validateField(city);
         validateEmail();
 
-        return !companyName.isInvalid() && !firstName.isInvalid() && !lastName.isInvalid() && !telephone.isInvalid()
-                && !mail.isInvalid() && !street.isInvalid() && !houseNumber.isInvalid() && !zip.isInvalid()
-                && !city.isInvalid();
+        return !firstName.isInvalid() && !lastName.isInvalid() && !telephone.isInvalid() && !mail.isInvalid()
+                && !street.isInvalid() && !houseNumber.isInvalid() && !zip.isInvalid() && !city.isInvalid();
     }
 
     @Override

backend/src/main/java/de/assecutor/votianlt/pages/view/AddJobView.java

@@ -63,6 +63,7 @@ import de.assecutor.votianlt.model.AddressValidationResult;
 import de.assecutor.votianlt.model.RouteCalculationResult;
 import de.assecutor.votianlt.pages.base.ui.component.DeliveryStationTile;
 import de.assecutor.votianlt.pages.base.ui.component.StationTile;
+import de.assecutor.votianlt.pages.base.ui.component.CustomerAddressLabelHelper;
 import de.assecutor.votianlt.pages.base.ui.component.PickupStationDialog;
 import de.assecutor.votianlt.pages.base.ui.component.DeliveryStationDialog;
 import de.assecutor.votianlt.pages.base.ui.component.DialogStylingHelper;
@@ -236,32 +237,19 @@ public class AddJobView extends Main implements HasDynamicTitle {
         customerSelection.setPlaceholder(getTranslation("addjob.customer.placeholder"));
         customerSelection.setWidthFull();
         customerSelection.setRequiredIndicatorVisible(true);
+        customerSelection.setAllowCustomValue(true);
+        customerSelection.addCustomValueSetListener(event -> setCustomerSelectionValue(event.getDetail()));
         // Mit Kunden des angemeldeten Benutzers befüllen und Mapping aufbauen
         List<Customer> ownerCustomers = customerService.findAllForCurrentOwner();
         customerLabelToEntity.clear();
         for (Customer c : ownerCustomers) {
-            String label = (c.getCompanyName() != null && !c.getCompanyName().isBlank())
-                    ? c.getCompanyName() + " | "
-                            + ((c.getFirstname() != null ? c.getFirstname() : "") + " "
-                                    + (c.getLastName() != null ? c.getLastName() : "")).trim()
-                    : ((c.getFirstname() != null ? c.getFirstname() : "") + " "
-                            + (c.getLastName() != null ? c.getLastName() : "")).trim();
-            if (label.isBlank()) {
-                label = getTranslation("addjob.customer.unnamed");
-            }
-            // Bei Duplikaten Label einzigartig machen
-            String uniqueLabel = label;
-            int counter = 2;
-            while (customerLabelToEntity.containsKey(uniqueLabel)) {
-                uniqueLabel = label + " (" + counter++ + ")";
-            }
-            customerLabelToEntity.put(uniqueLabel, c);
+            CustomerAddressLabelHelper.putUnique(customerLabelToEntity, c, getTranslation("addjob.customer.unnamed"));
         }
         customerSelection.setItems(new ArrayList<>(customerLabelToEntity.keySet()));
 
         // Pickup address
-        pickupCompany = new ComboBox<>(getTranslation("profile.company"));
-        pickupCompany.setPlaceholder(getTranslation("addjob.address.company.placeholder"));
+        pickupCompany = new ComboBox<>(getTranslation("addjob.address.pickup.label"));
+        pickupCompany.setPlaceholder(getTranslation("addjob.address.pickup.placeholder"));
         pickupCompany.setAllowCustomValue(true);
         setupCompanyAutocomplete(pickupCompany, true); // true für Pickup
         pickupSalutation = new ComboBox<>(getTranslation("addjob.address.salutation"));
@@ -857,7 +845,7 @@ public class AddJobView extends Main implements HasDynamicTitle {
                 translationHelper, data -> {
                     // Update customer selection from dialog
                     if (data.getCustomerSelection() != null) {
-                        customerSelection.setValue(data.getCustomerSelection());
+                        setCustomerSelectionValue(data.getCustomerSelection());
                     } else {
                         customerSelection.clear();
                     }
@@ -1116,6 +1104,19 @@ public class AddJobView extends Main implements HasDynamicTitle {
         return trimmed.isEmpty() ? null : trimmed;
     }
 
+    private void setCustomerSelectionValue(String value) {
+        String normalizedValue = trimToNull(value);
+        if (normalizedValue == null) {
+            customerSelection.clear();
+            return;
+        }
+        if (!customerLabelToEntity.containsKey(normalizedValue)) {
+            customerLabelToEntity.put(normalizedValue, null);
+            customerSelection.setItems(new ArrayList<>(customerLabelToEntity.keySet()));
+        }
+        customerSelection.setValue(normalizedValue);
+    }
+
     private void openDeliveryDialog(StationTile tile, int stationIndex) {
         // Ensure index is valid (could have changed due to deletions)
         int actualIndex = deliveryStationTilesList.indexOf(tile);
@@ -1412,30 +1413,29 @@ public class AddJobView extends Main implements HasDynamicTitle {
         // Get all customers for the current owner
         List<Customer> allCustomers = customerService.findAllForCurrentOwner();
 
-        // Extract unique company names (filter out null/empty values)
-        List<String> companyNames = allCustomers.stream().map(Customer::getCompanyName)
-                .filter(name -> name != null && !name.trim().isEmpty()).distinct().sorted().toList();
+        Map<String, Customer> addressOptions = new LinkedHashMap<>();
+        for (Customer customer : allCustomers) {
+            CustomerAddressLabelHelper.putUnique(addressOptions, customer, getTranslation("addjob.customer.unnamed"));
+        }
 
         // Set items for autocomplete
-        companyField.setItems(companyNames);
+        companyField.setItems(new ArrayList<>(addressOptions.keySet()));
 
         // Add selection listener to auto-fill pickup address fields when company is
         // selected
         companyField.addValueChangeListener(event -> {
-            String selectedCompany = event.getValue();
-            if (selectedCompany == null || selectedCompany.trim().isEmpty()) {
+            String selectedAddress = event.getValue();
+            if (selectedAddress == null || selectedAddress.trim().isEmpty()) {
                 return;
             }
 
             // Streckeninformationen zurücksetzen, da sich die Adresse ändert
             resetRouteInformation();
 
-            // Find the first customer with this company name
-            Optional<Customer> matchingCustomer = allCustomers.stream()
-                    .filter(c -> selectedCompany.equals(c.getCompanyName())).findFirst();
+            Customer customer = addressOptions.get(selectedAddress);
 
-            if (matchingCustomer.isPresent()) {
-                Customer customer = matchingCustomer.get();
+            if (customer != null) {
+                pickupCustomerId = customer.getId();
 
                 // Fill pickup address fields
                 if (customer.getTitle() != null
@@ -1476,6 +1476,7 @@ public class AddJobView extends Main implements HasDynamicTitle {
 
             // Reactivate save checkbox for custom values
             savePickupAddress.setValue(true);
+            pickupCustomerId = null;
             pickupMail = null;
         });
     }
@@ -1987,7 +1988,7 @@ public class AddJobView extends Main implements HasDynamicTitle {
      */
     private void loadJobIntoForm(Job job) {
         if (job.getCustomerSelection() != null) {
-            customerSelection.setValue(job.getCustomerSelection());
+            setCustomerSelectionValue(job.getCustomerSelection());
         }
     }
 

backend/src/main/java/de/assecutor/votianlt/pages/view/CreateInvoiceView.java

@@ -27,12 +27,13 @@ import de.assecutor.votianlt.model.invoices.CustomerInvoice;
 import de.assecutor.votianlt.pages.base.ui.component.DialogStylingHelper;
 import de.assecutor.votianlt.pages.service.CustomerService;
 import de.assecutor.votianlt.pages.service.UserInvoiceDataService;
-import de.assecutor.votianlt.repository.CustomerInvoiceRepository;
 import de.assecutor.votianlt.repository.JobRepository;
 import de.assecutor.votianlt.repository.ServiceRepository;
 import de.assecutor.votianlt.repository.UserRepository;
 import de.assecutor.votianlt.security.SecurityService;
 import de.assecutor.votianlt.service.CustomerInvoiceService;
+import de.assecutor.votianlt.service.InvoiceLifecycleException;
+import de.assecutor.votianlt.service.InvoiceLifecycleService;
 import de.assecutor.votianlt.service.InvoiceTemplateService;
 import jakarta.annotation.security.RolesAllowed;
 import lombok.extern.slf4j.Slf4j;
@@ -62,8 +63,8 @@ public class CreateInvoiceView extends VerticalLayout implements HasUrlParameter
     private final InvoiceTemplateService invoiceTemplateService;
     private final SecurityService securityService;
     private final UserInvoiceDataService userInvoiceDataService;
-    private final CustomerInvoiceRepository customerInvoiceRepository;
     private final CustomerService customerService;
+    private final InvoiceLifecycleService invoiceLifecycleService;
     private User currentUser;
     private Job currentJob;
     private List<ServiceRow> gridRows = new ArrayList<>();
@@ -117,8 +118,8 @@ public class CreateInvoiceView extends VerticalLayout implements HasUrlParameter
     public CreateInvoiceView(JobRepository jobRepository, ServiceRepository serviceRepository,
             UserRepository userRepository, CustomerInvoiceService customerInvoiceService,
             InvoiceTemplateService invoiceTemplateService, SecurityService securityService,
-            UserInvoiceDataService userInvoiceDataService, CustomerInvoiceRepository customerInvoiceRepository,
-            CustomerService customerService) {
+            UserInvoiceDataService userInvoiceDataService, CustomerService customerService,
+            InvoiceLifecycleService invoiceLifecycleService) {
         this.jobRepository = jobRepository;
         this.serviceRepository = serviceRepository;
         this.userRepository = userRepository;
@@ -126,8 +127,8 @@ public class CreateInvoiceView extends VerticalLayout implements HasUrlParameter
         this.invoiceTemplateService = invoiceTemplateService;
         this.securityService = securityService;
         this.userInvoiceDataService = userInvoiceDataService;
-        this.customerInvoiceRepository = customerInvoiceRepository;
         this.customerService = customerService;
+        this.invoiceLifecycleService = invoiceLifecycleService;
         setSizeFull();
         setPadding(true);
         setSpacing(true);
@@ -584,8 +585,12 @@ public class CreateInvoiceView extends VerticalLayout implements HasUrlParameter
             invoice.setVatRate(vatRate);
             invoice.setVatAmount(vatAmount);
             invoice.setTotalAmount(totalAmount);
+
             invoice.setPdfData(pdfBytes);
-            CustomerInvoice savedInvoice = customerInvoiceRepository.save(invoice);
+
+            // Finalisierung mit Audit-Eintrag und Eindeutigkeitsprüfung der Rechnungsnummer (R-07/R-11/R-36).
+            CustomerInvoice savedInvoice = invoiceLifecycleService.createAndIssue(invoice,
+                    "Rechnung erstellt aus Auftrag " + currentJob.getJobNumber());
 
             currentJob.setInvoiceId(savedInvoice.getId());
             jobRepository.save(currentJob);
@@ -594,6 +599,9 @@ public class CreateInvoiceView extends VerticalLayout implements HasUrlParameter
             Notification.show(getTranslation("createinvoice.notification.saved", invoiceNumber), 4000,
                     Notification.Position.BOTTOM_END);
 
+        } catch (InvoiceLifecycleException lifecycleEx) {
+            log.warn("Lifecycle-Verstoß beim Speichern der Rechnung: {}", lifecycleEx.getMessage());
+            Notification.show(lifecycleEx.getMessage(), 5000, Notification.Position.MIDDLE);
         } catch (Exception ex) {
             log.error("Fehler beim Speichern der Rechnung", ex);
             Notification.show(getTranslation("createinvoice.notification.error", ex.getMessage()), 5000,

backend/src/main/java/de/assecutor/votianlt/pages/view/EditCustomerView.java

@@ -191,6 +191,7 @@ public class EditCustomerView extends VerticalLayout implements HasUrlParameter<
 
         Button confirmDeleteButton = new Button(getTranslation("editcustomer.dialog.delete.confirm"), e -> {
             if (customer != null && customer.getId() != null) {
+                customerService.deleteById(customer.getId());
                 Notification.show(getTranslation("editcustomer.notification.deleted"), 3000,
                         Notification.Position.MIDDLE);
                 confirmDialog.close();

backend/src/main/java/de/assecutor/votianlt/pages/view/InvoicesView.java

@@ -1,39 +1,82 @@
 package de.assecutor.votianlt.pages.view;
 
+import com.vaadin.flow.component.Component;
+import com.vaadin.flow.component.UI;
+import com.vaadin.flow.component.button.Button;
+import com.vaadin.flow.component.button.ButtonVariant;
+import com.vaadin.flow.component.dialog.Dialog;
 import com.vaadin.flow.component.grid.Grid;
+import com.vaadin.flow.component.html.Anchor;
 import com.vaadin.flow.component.html.Div;
+import com.vaadin.flow.component.html.H3;
 import com.vaadin.flow.component.html.Span;
 import com.vaadin.flow.component.notification.Notification;
 import com.vaadin.flow.component.orderedlayout.FlexComponent;
+import com.vaadin.flow.component.orderedlayout.HorizontalLayout;
 import com.vaadin.flow.component.orderedlayout.VerticalLayout;
+import com.vaadin.flow.component.textfield.NumberField;
+import com.vaadin.flow.component.textfield.TextArea;
+import com.vaadin.flow.component.textfield.TextField;
 import com.vaadin.flow.router.HasDynamicTitle;
 import com.vaadin.flow.router.Route;
-import com.vaadin.flow.component.UI;
+import com.vaadin.flow.server.StreamRegistration;
+import com.vaadin.flow.server.StreamResource;
+import de.assecutor.votianlt.model.User;
 import de.assecutor.votianlt.model.invoices.CustomerInvoice;
+import de.assecutor.votianlt.model.invoices.InvoiceAuditEntry;
+import de.assecutor.votianlt.model.invoices.InvoiceStatus;
+import de.assecutor.votianlt.model.invoices.InvoiceType;
+import de.assecutor.votianlt.pages.base.ui.component.DialogStylingHelper;
 import de.assecutor.votianlt.pages.base.ui.component.ViewToolbar;
+import de.assecutor.votianlt.pages.service.UserInvoiceDataService;
 import de.assecutor.votianlt.repository.CustomerInvoiceRepository;
+import de.assecutor.votianlt.repository.UserRepository;
 import de.assecutor.votianlt.security.SecurityService;
+import de.assecutor.votianlt.service.CustomerInvoiceService;
+import de.assecutor.votianlt.service.InvoiceExportService;
+import de.assecutor.votianlt.service.InvoiceLifecycleException;
+import de.assecutor.votianlt.service.InvoiceLifecycleService;
+import de.assecutor.votianlt.service.InvoicePermissionService;
 import jakarta.annotation.security.RolesAllowed;
 
 import java.io.ByteArrayInputStream;
+import java.time.LocalDate;
+import java.time.format.DateTimeFormatter;
+import java.util.Comparator;
 import java.util.List;
 import java.util.Locale;
 import java.util.Optional;
 
-import com.vaadin.flow.server.StreamResource;
-import com.vaadin.flow.server.StreamRegistration;
-
 @Route(value = "invoices", layout = de.assecutor.votianlt.pages.base.ui.view.MainLayout.class)
 @RolesAllowed({ "USER", "ADMIN" })
 public class InvoicesView extends VerticalLayout implements HasDynamicTitle {
 
+    private static final DateTimeFormatter DATE_TIME_FMT = DateTimeFormatter.ofPattern("dd.MM.yyyy HH:mm",
+            Locale.GERMANY);
+
     private final Grid<CustomerInvoice> invoiceGrid;
     private final CustomerInvoiceRepository customerInvoiceRepository;
     private final SecurityService securityService;
+    private final InvoiceLifecycleService invoiceLifecycleService;
+    private final CustomerInvoiceService customerInvoiceService;
+    private final InvoiceExportService invoiceExportService;
+    private final InvoicePermissionService invoicePermissionService;
+    private final UserInvoiceDataService userInvoiceDataService;
+    private final UserRepository userRepository;
 
-    public InvoicesView(CustomerInvoiceRepository customerInvoiceRepository, SecurityService securityService) {
+    public InvoicesView(CustomerInvoiceRepository customerInvoiceRepository, SecurityService securityService,
+            InvoiceLifecycleService invoiceLifecycleService, CustomerInvoiceService customerInvoiceService,
+            InvoiceExportService invoiceExportService, InvoicePermissionService invoicePermissionService,
+            UserInvoiceDataService userInvoiceDataService,
+            UserRepository userRepository) {
         this.customerInvoiceRepository = customerInvoiceRepository;
         this.securityService = securityService;
+        this.invoiceLifecycleService = invoiceLifecycleService;
+        this.customerInvoiceService = customerInvoiceService;
+        this.invoiceExportService = invoiceExportService;
+        this.invoicePermissionService = invoicePermissionService;
+        this.userInvoiceDataService = userInvoiceDataService;
+        this.userRepository = userRepository;
 
         setSizeFull();
         setPadding(true);
@@ -43,60 +86,502 @@ public class InvoicesView extends VerticalLayout implements HasDynamicTitle {
         addClassName("data-view");
 
         add(new ViewToolbar(getTranslation("invoices.title")));
+        add(buildLegalDisclaimer());
 
         invoiceGrid = new Grid<>(CustomerInvoice.class, false);
         invoiceGrid.setWidthFull();
         invoiceGrid.addClassName("data-grid");
         invoiceGrid.addColumn(invoice -> firstNonBlank(invoice.getInvoiceNumber(), invoice.getId()))
                 .setHeader(getTranslation("invoices.column.number")).setAutoWidth(true);
+        invoiceGrid.addComponentColumn(this::renderTypeBadge)
+                .setHeader(getTranslation("invoices.column.type")).setAutoWidth(true);
+        invoiceGrid.addComponentColumn(this::renderStatusBadge)
+                .setHeader(getTranslation("invoices.column.status")).setAutoWidth(true);
         invoiceGrid.addColumn(this::getRecipientLabel).setHeader(getTranslation("invoices.column.customer"))
                 .setAutoWidth(true);
         invoiceGrid.addColumn(invoice -> Optional.ofNullable(invoice.getInvoiceDate()).map(Object::toString).orElse(""))
                 .setHeader(getTranslation("invoices.column.date")).setAutoWidth(true);
         invoiceGrid.addColumn(this::formatAmount).setHeader(getTranslation("invoices.column.amount"))
                 .setAutoWidth(true);
-        invoiceGrid.addColumn(invoice -> firstNonBlank(invoice.getDescription(), ""))
-                .setHeader(getTranslation("invoices.column.description")).setAutoWidth(true);
-        invoiceGrid.setSelectionMode(Grid.SelectionMode.SINGLE);
-        invoiceGrid.getStyle().set("cursor", "pointer");
+        invoiceGrid.addComponentColumn(this::renderActions)
+                .setHeader(getTranslation("invoices.column.actions")).setAutoWidth(true).setFlexGrow(0);
 
-        invoiceGrid.addItemClickListener(event -> {
-            CustomerInvoice invoice = event.getItem();
-            if (invoice != null) {
-                downloadInvoicePdf(invoice);
-            }
-        });
+        invoiceGrid.setSelectionMode(Grid.SelectionMode.NONE);
 
-        loadInvoices();
         Div gridPanel = new Div(invoiceGrid);
         gridPanel.addClassNames("surface-panel", "data-grid-panel");
         gridPanel.setWidthFull();
 
         add(gridPanel);
+
+        loadInvoices();
+    }
+
+    private Component buildLegalDisclaimer() {
+        Div banner = new Div();
+        banner.addClassName("surface-panel");
+        banner.getStyle().set("padding", "12px 16px").set("border-left", "4px solid var(--lumo-primary-color)")
+                .set("background", "var(--lumo-contrast-5pct)");
+        Span text = new Span(getTranslation("invoices.disclaimer"));
+        text.getStyle().set("font-size", "var(--lumo-font-size-s)");
+        banner.add(text);
+        return banner;
     }
 
     private void loadInvoices() {
         String currentUserId = securityService.getCurrentUserId().toHexString();
         List<CustomerInvoice> invoices = customerInvoiceRepository.findByUserId(currentUserId).stream()
-                .filter(this::hasPdfData).sorted((left, right) -> {
-                    if (left.getInvoiceDate() == null && right.getInvoiceDate() == null) {
-                        return 0;
-                    }
-                    if (left.getInvoiceDate() == null) {
-                        return 1;
-                    }
-                    if (right.getInvoiceDate() == null) {
-                        return -1;
-                    }
-                    return right.getInvoiceDate().compareTo(left.getInvoiceDate());
-                }).toList();
+                .sorted(Comparator
+                        .comparing((CustomerInvoice i) -> i.getInvoiceDate() == null ? LocalDate.MIN
+                                : i.getInvoiceDate())
+                        .reversed())
+                .toList();
         invoiceGrid.setItems(invoices);
+    }
 
-        if (invoices.isEmpty()) {
-            Span emptyState = new Span(getTranslation("invoices.empty"));
-            emptyState.getStyle().set("color", "var(--lumo-secondary-text-color)");
-            add(emptyState);
+    private Component renderStatusBadge(CustomerInvoice invoice) {
+        InvoiceStatus status = invoice.getStatus() != null ? invoice.getStatus() : InvoiceStatus.ISSUED;
+        Span badge = new Span(getTranslation("invoices.status." + status.name().toLowerCase(Locale.ROOT)));
+        badge.getElement().getThemeList().add("badge");
+        switch (status) {
+        case DRAFT -> badge.getElement().getThemeList().add("contrast");
+        case SENT -> badge.getElement().getThemeList().add("success");
+        case CANCELLED -> badge.getElement().getThemeList().add("error");
+        case CORRECTED -> badge.getElement().getThemeList().add("warning");
+        default -> {
         }
+        }
+        return badge;
+    }
+
+    private Component renderTypeBadge(CustomerInvoice invoice) {
+        InvoiceType type = invoice.getType() != null ? invoice.getType() : InvoiceType.INVOICE;
+        HorizontalLayout layout = new HorizontalLayout();
+        layout.setSpacing(true);
+        layout.setPadding(false);
+
+        Span badge = new Span(getTranslation("invoices.type." + type.name().toLowerCase(Locale.ROOT)));
+        badge.getElement().getThemeList().add("badge");
+        if (type == InvoiceType.CANCELLATION) {
+            badge.getElement().getThemeList().add("error");
+        } else if (type == InvoiceType.CORRECTION) {
+            badge.getElement().getThemeList().add("warning");
+        }
+        layout.add(badge);
+        return layout;
+    }
+
+    private Component renderActions(CustomerInvoice invoice) {
+        HorizontalLayout actions = new HorizontalLayout();
+        actions.setSpacing(true);
+        actions.setPadding(false);
+
+        Button viewBtn = new Button(getTranslation("invoices.action.view"), e -> downloadInvoicePdf(invoice));
+        viewBtn.addThemeVariants(ButtonVariant.LUMO_TERTIARY, ButtonVariant.LUMO_SMALL);
+        viewBtn.setEnabled(invoice.getPdfData() != null && invoice.getPdfData().length > 0);
+        actions.add(viewBtn);
+
+        Button historyBtn = new Button(getTranslation("invoices.action.history"), e -> openHistoryDialog(invoice));
+        historyBtn.addThemeVariants(ButtonVariant.LUMO_TERTIARY, ButtonVariant.LUMO_SMALL);
+        actions.add(historyBtn);
+
+        InvoiceStatus status = invoice.getStatus() != null ? invoice.getStatus() : InvoiceStatus.ISSUED;
+        InvoiceType type = invoice.getType() != null ? invoice.getType() : InvoiceType.INVOICE;
+        User currentUser = invoicePermissionService.currentUser();
+
+        // Aktionen nur für reguläre, noch aktive Rechnungen anbieten
+        boolean isLiveInvoice = type == InvoiceType.INVOICE
+                && (status == InvoiceStatus.ISSUED || status == InvoiceStatus.SENT);
+
+        if (type == InvoiceType.INVOICE && status == InvoiceStatus.ISSUED
+                && invoicePermissionService.canMarkAsSent(currentUser)) {
+            Button sentBtn = new Button(getTranslation("invoices.action.marksent"),
+                    e -> markAsSent(invoice));
+            sentBtn.addThemeVariants(ButtonVariant.LUMO_SMALL);
+            actions.add(sentBtn);
+        }
+
+        if (isLiveInvoice) {
+            if (invoicePermissionService.canCorrect(currentUser)) {
+                Button correctBtn = new Button(getTranslation("invoices.action.correct"),
+                        e -> openCorrectionDialog(invoice));
+                correctBtn.addThemeVariants(ButtonVariant.LUMO_SMALL);
+                actions.add(correctBtn);
+            }
+
+            if (invoicePermissionService.canCancel(currentUser)) {
+                Button cancelBtn = new Button(getTranslation("invoices.action.cancel"),
+                        e -> openCancellationDialog(invoice));
+                cancelBtn.addThemeVariants(ButtonVariant.LUMO_SMALL, ButtonVariant.LUMO_ERROR);
+                actions.add(cancelBtn);
+            }
+        }
+
+        // Zahlung erfassen: nur für reguläre Rechnungen (R-25)
+        if (type == InvoiceType.INVOICE && status != InvoiceStatus.DRAFT
+                && invoicePermissionService.canRecordPayment(currentUser)) {
+            Button payBtn = new Button(getTranslation("invoices.action.payment"),
+                    e -> openPaymentDialog(invoice));
+            payBtn.addThemeVariants(ButtonVariant.LUMO_SMALL);
+            actions.add(payBtn);
+        }
+
+        // Belegpaket exportieren (R-33/R-34)
+        Button exportBtn = new Button(getTranslation("invoices.action.export"), e -> exportPackage(invoice));
+        exportBtn.addThemeVariants(ButtonVariant.LUMO_TERTIARY, ButtonVariant.LUMO_SMALL);
+        actions.add(exportBtn);
+
+        return actions;
+    }
+
+    private void openPaymentDialog(CustomerInvoice invoice) {
+        Dialog dialog = DialogStylingHelper.createStyledDialog(
+                getTranslation("invoices.payment.title", invoice.getInvoiceNumber()), "480px");
+
+        VerticalLayout content = new VerticalLayout();
+        content.setSpacing(true);
+        content.setPadding(false);
+
+        java.math.BigDecimal outstanding = invoiceLifecycleService.computeOutstandingAmount(invoice);
+        Span hint = new Span(getTranslation("invoices.payment.hint",
+                java.text.NumberFormat.getCurrencyInstance(Locale.GERMANY).format(outstanding)));
+        hint.getStyle().set("color", "var(--lumo-secondary-text-color)")
+                .set("font-size", "var(--lumo-font-size-s)");
+        content.add(hint);
+
+        NumberField amountField = new NumberField(getTranslation("invoices.payment.amount"));
+        amountField.setStep(0.01);
+        amountField.setValue(outstanding.doubleValue());
+        amountField.setRequiredIndicatorVisible(true);
+        amountField.setWidthFull();
+        content.add(amountField);
+
+        TextField referenceField = new TextField(getTranslation("invoices.payment.reference"));
+        referenceField.setWidthFull();
+        content.add(referenceField);
+
+        TextArea reasonField = new TextArea(getTranslation("invoices.payment.reason"));
+        reasonField.setWidthFull();
+        reasonField.setMinHeight("80px");
+        content.add(reasonField);
+
+        dialog.add(DialogStylingHelper.wrapContent(content));
+
+        Button cancelBtn = new Button(getTranslation("button.cancel"), e -> dialog.close());
+        cancelBtn.addThemeVariants(ButtonVariant.LUMO_TERTIARY);
+
+        Button confirmBtn = new Button(getTranslation("invoices.payment.confirm"), e -> {
+            Double amount = amountField.getValue();
+            if (amount == null || amount == 0d) {
+                amountField.setInvalid(true);
+                amountField.setErrorMessage(getTranslation("invoices.payment.amount.required"));
+                return;
+            }
+            performPayment(invoice, java.math.BigDecimal.valueOf(amount), referenceField.getValue(),
+                    reasonField.getValue(), dialog);
+        });
+        confirmBtn.addThemeVariants(ButtonVariant.LUMO_PRIMARY);
+
+        dialog.getFooter().add(cancelBtn, confirmBtn);
+        dialog.open();
+    }
+
+    private void performPayment(CustomerInvoice invoice, java.math.BigDecimal amount, String reference, String reason,
+            Dialog dialog) {
+        try {
+            invoicePermissionService.requirePayment(invoicePermissionService.currentUser());
+            invoiceLifecycleService.registerPayment(invoice.getId(), amount, reference, reason);
+            dialog.close();
+            Notification.show(getTranslation("invoices.notification.payment"), 3000, Notification.Position.BOTTOM_END);
+            loadInvoices();
+        } catch (InvoiceLifecycleException ex) {
+            Notification.show(ex.getMessage(), 6000, Notification.Position.MIDDLE);
+        } catch (Exception ex) {
+            Notification.show(getTranslation("invoices.notification.error", ex.getMessage()), 6000,
+                    Notification.Position.MIDDLE);
+        }
+    }
+
+    private void exportPackage(CustomerInvoice invoice) {
+        try {
+            byte[] zipBytes = invoiceExportService.exportInvoicePackage(invoice);
+            String fileName = invoiceExportService.suggestFilename(invoice);
+            StreamResource resource = new StreamResource(fileName, () -> new ByteArrayInputStream(zipBytes));
+            resource.setContentType("application/zip");
+            resource.setCacheTime(0);
+            StreamRegistration registration = UI.getCurrent().getSession().getResourceRegistry()
+                    .registerResource(resource);
+            UI.getCurrent().getPage().open(registration.getResourceUri().toString());
+        } catch (Exception ex) {
+            Notification.show(getTranslation("invoices.notification.error", ex.getMessage()), 6000,
+                    Notification.Position.MIDDLE);
+        }
+    }
+
+    private void markAsSent(CustomerInvoice invoice) {
+        try {
+            invoicePermissionService.requireSend(invoicePermissionService.currentUser());
+            invoiceLifecycleService.markAsSent(invoice.getId(), "Manuell als versendet markiert");
+            Notification.show(getTranslation("invoices.notification.sent"), 3000, Notification.Position.BOTTOM_END);
+            loadInvoices();
+        } catch (InvoiceLifecycleException ex) {
+            Notification.show(ex.getMessage(), 5000, Notification.Position.MIDDLE);
+        }
+    }
+
+    private void openCancellationDialog(CustomerInvoice invoice) {
+        Dialog dialog = DialogStylingHelper.createStyledDialog(
+                getTranslation("invoices.cancel.title", invoice.getInvoiceNumber()), "560px");
+
+        VerticalLayout content = new VerticalLayout();
+        content.setSpacing(true);
+        content.setPadding(false);
+
+        Span hint = new Span(getTranslation("invoices.cancel.hint"));
+        hint.getStyle().set("color", "var(--lumo-secondary-text-color)")
+                .set("font-size", "var(--lumo-font-size-s)");
+        content.add(hint);
+
+        TextArea reasonField = new TextArea(getTranslation("invoices.cancel.reason"));
+        reasonField.setWidthFull();
+        reasonField.setMinHeight("100px");
+        reasonField.setRequired(true);
+        content.add(reasonField);
+
+        dialog.add(DialogStylingHelper.wrapContent(content));
+
+        Button cancelBtn = new Button(getTranslation("button.cancel"), e -> dialog.close());
+        cancelBtn.addThemeVariants(ButtonVariant.LUMO_TERTIARY);
+
+        Button confirmBtn = new Button(getTranslation("invoices.cancel.confirm"), e -> {
+            String reason = reasonField.getValue();
+            if (reason == null || reason.isBlank()) {
+                reasonField.setInvalid(true);
+                reasonField.setErrorMessage(getTranslation("invoices.cancel.reason.required"));
+                return;
+            }
+            performCancellation(invoice, reason, dialog);
+        });
+        confirmBtn.addThemeVariants(ButtonVariant.LUMO_PRIMARY, ButtonVariant.LUMO_ERROR);
+
+        dialog.getFooter().add(cancelBtn, confirmBtn);
+        dialog.open();
+    }
+
+    private void performCancellation(CustomerInvoice invoice, String reason, Dialog dialog) {
+        User currentUser = invoicePermissionService.currentUser();
+        try {
+            invoicePermissionService.requireCancel(currentUser);
+            User issuer = resolveIssuer(invoice);
+            String number = userInvoiceDataService.generateNextInvoiceNumber(issuer.getId());
+            LocalDate today = LocalDate.now();
+            byte[] pdf = customerInvoiceService.generateCancellationPdf(invoice, number, today, reason);
+            invoiceLifecycleService.cancel(invoice.getId(), number, today, pdf, reason);
+            dialog.close();
+            Notification.show(getTranslation("invoices.notification.cancelled", number), 4000,
+                    Notification.Position.BOTTOM_END);
+            loadInvoices();
+        } catch (InvoiceLifecycleException ex) {
+            Notification.show(ex.getMessage(), 6000, Notification.Position.MIDDLE);
+        } catch (Exception ex) {
+            Notification.show(getTranslation("invoices.notification.error", ex.getMessage()), 6000,
+                    Notification.Position.MIDDLE);
+        }
+    }
+
+    private void openCorrectionDialog(CustomerInvoice invoice) {
+        Dialog dialog = DialogStylingHelper.createStyledDialog(
+                getTranslation("invoices.correct.title", invoice.getInvoiceNumber()), "560px");
+
+        VerticalLayout content = new VerticalLayout();
+        content.setSpacing(true);
+        content.setPadding(false);
+
+        Span hint = new Span(getTranslation("invoices.correct.hint"));
+        hint.getStyle().set("color", "var(--lumo-secondary-text-color)")
+                .set("font-size", "var(--lumo-font-size-s)");
+        content.add(hint);
+
+        TextArea fieldsField = new TextArea(getTranslation("invoices.correct.fields"));
+        fieldsField.setWidthFull();
+        fieldsField.setMinHeight("100px");
+        fieldsField.setHelperText(getTranslation("invoices.correct.fields.helper"));
+        fieldsField.setRequired(true);
+        content.add(fieldsField);
+
+        TextArea reasonField = new TextArea(getTranslation("invoices.correct.reason"));
+        reasonField.setWidthFull();
+        reasonField.setMinHeight("80px");
+        content.add(reasonField);
+
+        dialog.add(DialogStylingHelper.wrapContent(content));
+
+        Button cancelBtn = new Button(getTranslation("button.cancel"), e -> dialog.close());
+        cancelBtn.addThemeVariants(ButtonVariant.LUMO_TERTIARY);
+
+        Button confirmBtn = new Button(getTranslation("invoices.correct.confirm"), e -> {
+            String fields = fieldsField.getValue();
+            if (fields == null || fields.isBlank()) {
+                fieldsField.setInvalid(true);
+                fieldsField.setErrorMessage(getTranslation("invoices.correct.fields.required"));
+                return;
+            }
+            performCorrection(invoice, fields, reasonField.getValue(), dialog);
+        });
+        confirmBtn.addThemeVariants(ButtonVariant.LUMO_PRIMARY);
+
+        dialog.getFooter().add(cancelBtn, confirmBtn);
+        dialog.open();
+    }
+
+    private void performCorrection(CustomerInvoice invoice, String correctedFields, String reason, Dialog dialog) {
+        User currentUser = invoicePermissionService.currentUser();
+        try {
+            invoicePermissionService.requireCorrect(currentUser);
+            User issuer = resolveIssuer(invoice);
+            String number = userInvoiceDataService.generateNextInvoiceNumber(issuer.getId());
+            LocalDate today = LocalDate.now();
+            byte[] pdf = customerInvoiceService.generateCorrectionPdf(invoice, number, today, reason, correctedFields);
+            invoiceLifecycleService.correct(invoice.getId(), number, today, pdf, correctedFields, reason);
+            dialog.close();
+            Notification.show(getTranslation("invoices.notification.corrected", number), 4000,
+                    Notification.Position.BOTTOM_END);
+            loadInvoices();
+        } catch (InvoiceLifecycleException ex) {
+            Notification.show(ex.getMessage(), 6000, Notification.Position.MIDDLE);
+        } catch (Exception ex) {
+            Notification.show(getTranslation("invoices.notification.error", ex.getMessage()), 6000,
+                    Notification.Position.MIDDLE);
+        }
+    }
+
+    private User resolveIssuer(CustomerInvoice invoice) {
+        if (invoice.getUserId() != null && !invoice.getUserId().isBlank()) {
+            try {
+                return userRepository.findById(new org.bson.types.ObjectId(invoice.getUserId()))
+                        .orElseGet(securityService::getCurrentDatabaseUser);
+            } catch (IllegalArgumentException ex) {
+                // userId ist kein gültiger ObjectId – Fallback auf eingeloggten Nutzer
+            }
+        }
+        return securityService.getCurrentDatabaseUser();
+    }
+
+    private void openHistoryDialog(CustomerInvoice invoice) {
+        Dialog dialog = DialogStylingHelper.createStyledDialog(
+                getTranslation("invoices.history.title", invoice.getInvoiceNumber()), "640px");
+
+        VerticalLayout content = new VerticalLayout();
+        content.setSpacing(true);
+        content.setPadding(false);
+
+        // Verkettung anzeigen, falls vorhanden
+        Div linksBlock = renderRelatedInvoiceLinks(invoice);
+        if (linksBlock != null) {
+            content.add(linksBlock);
+        }
+
+        H3 logTitle = new H3(getTranslation("invoices.history.log"));
+        content.add(logTitle);
+
+        List<InvoiceAuditEntry> log = invoice.getAuditLog();
+        if (log == null || log.isEmpty()) {
+            content.add(new Span(getTranslation("invoices.history.empty")));
+        } else {
+            log.stream()
+                    .sorted(Comparator
+                            .comparing((InvoiceAuditEntry e) -> e.getTimestamp() == null
+                                    ? java.time.LocalDateTime.MIN
+                                    : e.getTimestamp())
+                            .reversed())
+                    .forEach(entry -> content.add(renderAuditEntry(entry)));
+        }
+
+        dialog.add(DialogStylingHelper.wrapContent(content, true));
+
+        Button closeBtn = new Button(getTranslation("button.close"), e -> dialog.close());
+        closeBtn.addThemeVariants(ButtonVariant.LUMO_TERTIARY);
+        dialog.getFooter().add(closeBtn);
+        dialog.open();
+    }
+
+    private Div renderRelatedInvoiceLinks(CustomerInvoice invoice) {
+        Div block = new Div();
+        boolean hasContent = false;
+        if (invoice.getOriginalInvoiceId() != null) {
+            block.add(buildLinkRow(getTranslation("invoices.history.original"),
+                    invoice.getOriginalInvoiceNumber(), invoice.getOriginalInvoiceId()));
+            hasContent = true;
+        }
+        if (invoice.getCancellationInvoiceId() != null) {
+            block.add(buildLinkRow(getTranslation("invoices.history.cancellation"),
+                    null, invoice.getCancellationInvoiceId()));
+            hasContent = true;
+        }
+        if (invoice.getCorrectionInvoiceId() != null) {
+            block.add(buildLinkRow(getTranslation("invoices.history.correction"),
+                    null, invoice.getCorrectionInvoiceId()));
+            hasContent = true;
+        }
+        if (invoice.getReplacementInvoiceId() != null) {
+            block.add(buildLinkRow(getTranslation("invoices.history.replacement"),
+                    null, invoice.getReplacementInvoiceId()));
+            hasContent = true;
+        }
+        return hasContent ? block : null;
+    }
+
+    private HorizontalLayout buildLinkRow(String label, String fallbackNumber, String invoiceId) {
+        HorizontalLayout row = new HorizontalLayout();
+        row.setSpacing(true);
+        row.setPadding(false);
+        Span lbl = new Span(label);
+        lbl.getStyle().set("min-width", "180px").set("color", "var(--lumo-secondary-text-color)");
+        row.add(lbl);
+
+        CustomerInvoice related = invoiceLifecycleService.findById(invoiceId).orElse(null);
+        String number = related != null && related.getInvoiceNumber() != null ? related.getInvoiceNumber()
+                : fallbackNumber != null ? fallbackNumber : invoiceId;
+        if (related != null && related.getPdfData() != null && related.getPdfData().length > 0) {
+            Anchor link = new Anchor("javascript:void(0)", number);
+            link.getElement().addEventListener("click", e -> downloadInvoicePdf(related));
+            row.add(link);
+        } else {
+            row.add(new Span(number));
+        }
+        return row;
+    }
+
+    private Div renderAuditEntry(InvoiceAuditEntry entry) {
+        Div container = new Div();
+        container.getStyle().set("padding", "8px 12px").set("margin-bottom", "6px")
+                .set("border-left", "3px solid var(--lumo-contrast-30pct)")
+                .set("background", "var(--lumo-contrast-5pct)");
+
+        String timestamp = entry.getTimestamp() != null ? entry.getTimestamp().format(DATE_TIME_FMT) : "—";
+        String actionLabel = entry.getAction() != null
+                ? getTranslation("invoices.audit.action." + entry.getAction().name().toLowerCase(Locale.ROOT))
+                : "?";
+        String userLabel = entry.getUserDisplayName() != null ? entry.getUserDisplayName() : "system";
+
+        Span header = new Span(timestamp + " · " + actionLabel + " · " + userLabel);
+        header.getStyle().set("font-weight", "600");
+        container.add(header);
+
+        if (entry.getReason() != null && !entry.getReason().isBlank()) {
+            Div reason = new Div();
+            reason.setText(entry.getReason());
+            reason.getStyle().set("margin-top", "4px");
+            container.add(reason);
+        }
+        if (entry.getResultingInvoiceNumber() != null) {
+            Div link = new Div();
+            link.setText(getTranslation("invoices.audit.resulting", entry.getResultingInvoiceNumber()));
+            link.getStyle().set("margin-top", "4px").set("color", "var(--lumo-secondary-text-color)")
+                    .set("font-size", "var(--lumo-font-size-s)");
+            container.add(link);
+        }
+        return container;
     }
 
     private void downloadInvoicePdf(CustomerInvoice invoice) {
@@ -123,10 +608,6 @@ public class InvoicesView extends VerticalLayout implements HasDynamicTitle {
         }
     }
 
-    private boolean hasPdfData(CustomerInvoice invoice) {
-        return invoice != null && invoice.getPdfData() != null && invoice.getPdfData().length > 0;
-    }
-
     private String getRecipientLabel(CustomerInvoice invoice) {
         return firstNonBlank(invoice.getRecipientCompany(), invoice.getRecipientName(), "");
     }

backend/src/main/java/de/assecutor/votianlt/pages/view/JobManualCompleteView.java

@@ -2,22 +2,38 @@ package de.assecutor.votianlt.pages.view;
 
 import com.vaadin.flow.component.button.Button;
 import com.vaadin.flow.component.button.ButtonVariant;
+import com.vaadin.flow.component.combobox.ComboBox;
+import com.vaadin.flow.component.dialog.Dialog;
+import com.vaadin.flow.component.grid.Grid;
+import com.vaadin.flow.component.html.Div;
+import com.vaadin.flow.component.html.H3;
 import com.vaadin.flow.component.html.Main;
 import com.vaadin.flow.component.html.Span;
+import com.vaadin.flow.component.icon.Icon;
+import com.vaadin.flow.component.icon.VaadinIcon;
 import com.vaadin.flow.component.notification.Notification;
 import com.vaadin.flow.component.notification.NotificationVariant;
+import com.vaadin.flow.component.orderedlayout.FlexComponent;
 import com.vaadin.flow.component.orderedlayout.HorizontalLayout;
 import com.vaadin.flow.component.orderedlayout.VerticalLayout;
+import com.vaadin.flow.component.textfield.IntegerField;
+import com.vaadin.flow.component.textfield.NumberField;
 import com.vaadin.flow.component.textfield.TextArea;
 import com.vaadin.flow.router.BeforeEvent;
 import com.vaadin.flow.router.HasDynamicTitle;
 import com.vaadin.flow.router.HasUrlParameter;
 import com.vaadin.flow.router.Route;
 import com.vaadin.flow.theme.lumo.LumoUtility;
+import de.assecutor.votianlt.model.DeliveryStation;
 import de.assecutor.votianlt.model.Job;
 import de.assecutor.votianlt.model.JobHistoryType;
+import de.assecutor.votianlt.model.JobServiceSelection;
 import de.assecutor.votianlt.model.JobStatus;
+import de.assecutor.votianlt.model.Service;
+import de.assecutor.votianlt.model.User;
+import de.assecutor.votianlt.pages.base.ui.component.DialogStylingHelper;
 import de.assecutor.votianlt.pages.base.ui.component.ViewToolbar;
+import de.assecutor.votianlt.repository.ServiceRepository;
 import de.assecutor.votianlt.repository.JobRepository;
 import de.assecutor.votianlt.security.SecurityService;
 import de.assecutor.votianlt.service.JobHistoryService;
@@ -25,23 +41,50 @@ import jakarta.annotation.security.RolesAllowed;
 import lombok.extern.slf4j.Slf4j;
 import org.bson.types.ObjectId;
 
+import java.math.BigDecimal;
+import java.math.RoundingMode;
 import java.time.LocalDateTime;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Locale;
 
 @Route(value = "job_manual_complete", layout = de.assecutor.votianlt.pages.base.ui.view.MainLayout.class)
 @RolesAllowed("USER")
 @Slf4j
 public class JobManualCompleteView extends Main implements HasUrlParameter<String>, HasDynamicTitle {
 
+    private static final class ServiceRow {
+        private final Service service;
+        private final JobServiceSelection selection;
+
+        private ServiceRow(Service service, JobServiceSelection selection) {
+            this.service = service;
+            this.selection = selection;
+        }
+    }
+
     private final JobRepository jobRepository;
     private final JobHistoryService jobHistoryService;
     private final SecurityService securityService;
+    private final ServiceRepository serviceRepository;
     private final VerticalLayout content;
 
+    private Job job;
+    private final List<ServiceRow> serviceRows = new ArrayList<>();
+    private Grid<ServiceRow> servicesGrid;
+    private Span netTotalLabel;
+    private Span grossTotalLabel;
+    private TextArea remarkArea;
+    private BigDecimal vatRate = Service.FIXED_VAT_RATE;
+    private Double manualDistanceKm;
+    private Integer manualDurationSeconds;
+
     public JobManualCompleteView(JobRepository jobRepository, JobHistoryService jobHistoryService,
-            SecurityService securityService) {
+            SecurityService securityService, ServiceRepository serviceRepository) {
         this.jobRepository = jobRepository;
         this.jobHistoryService = jobHistoryService;
         this.securityService = securityService;
+        this.serviceRepository = serviceRepository;
 
         setSizeFull();
         addClassNames(LumoUtility.BoxSizing.BORDER, LumoUtility.Display.FLEX, LumoUtility.FlexDirection.COLUMN,
@@ -66,6 +109,8 @@ public class JobManualCompleteView extends Main implements HasUrlParameter<Strin
     @Override
     public void setParameter(BeforeEvent event, String parameter) {
         content.removeAll();
+        serviceRows.clear();
+        job = null;
 
         if (parameter == null || parameter.isBlank()) {
             content.add(new Span(getTranslation("jobhistory.error.no.id")));
@@ -80,16 +125,32 @@ public class JobManualCompleteView extends Main implements HasUrlParameter<Strin
             return;
         }
 
-        Job job = jobRepository.findById(jobId).orElse(null);
-        if (job == null) {
+        Job loaded = jobRepository.findById(jobId).orElse(null);
+        if (loaded == null) {
             content.add(new Span(getTranslation("jobhistory.error.not.found", parameter)));
             return;
         }
 
-        render(job);
+        job = loaded;
+        loadVatRate();
+        render();
     }
 
-    private void render(Job job) {
+    private void loadVatRate() {
+        try {
+            User user = securityService.getCurrentDatabaseUser();
+            if (user != null && user.getVatRate() != null) {
+                vatRate = user.getVatRate();
+            }
+        } catch (Exception e) {
+            log.warn("Could not load user VAT rate, falling back to default: {}", e.getMessage());
+        }
+    }
+
+    private void render() {
+        manualDistanceKm = job.getRouteDistanceKm();
+        manualDurationSeconds = job.getRouteDurationSeconds();
+
         Span warningText = new Span(getTranslation("jobsummary.dialog.manualcomplete.text", job.getJobNumber()));
         warningText.getStyle().set("color", "var(--lumo-error-text-color)");
 
@@ -100,9 +161,16 @@ public class JobManualCompleteView extends Main implements HasUrlParameter<Strin
 
         content.add(warningText, reasonField);
 
+        boolean hasRouteData = manualDistanceKm != null && manualDistanceKm > 0;
+        content.add(hasRouteData ? createRouteSection() : createManualRouteSection());
+
+        content.add(createServicesSection());
+        content.add(createSummarySection());
+        content.add(createRemarkSection());
+
         HorizontalLayout buttonBar = new HorizontalLayout();
         buttonBar.setWidthFull();
-        buttonBar.setJustifyContentMode(HorizontalLayout.JustifyContentMode.END);
+        buttonBar.setJustifyContentMode(FlexComponent.JustifyContentMode.END);
         buttonBar.setSpacing(true);
 
         Button cancelButton = new Button(getTranslation("jobsummary.dialog.manualcomplete.cancel"),
@@ -110,43 +178,521 @@ public class JobManualCompleteView extends Main implements HasUrlParameter<Strin
 
         Button confirmButton = new Button(getTranslation("jobsummary.dialog.manualcomplete.confirm"));
         confirmButton.addThemeVariants(ButtonVariant.LUMO_PRIMARY, ButtonVariant.LUMO_ERROR);
-        confirmButton.addClickListener(e -> {
-            String reason = reasonField.getValue();
-            if (reason == null || reason.trim().isEmpty()) {
-                reasonField.setInvalid(true);
-                reasonField.setErrorMessage(getTranslation("jobsummary.dialog.manualcomplete.reason.required"));
-                return;
-            }
-
-            try {
-                JobStatus oldStatus = job.getStatus();
-                job.setStatus(JobStatus.COMPLETED);
-                job.setUpdatedAt(LocalDateTime.now());
-                jobRepository.save(job);
-
-                String currentUser = securityService.getCurrentUsername();
-                jobHistoryService.logStatusChange(job, oldStatus, JobStatus.COMPLETED, currentUser);
-
-                String description = String.format("Auftrag manuell beendet von %s. Begründung: %s",
-                        currentUser, reason.trim());
-                jobHistoryService.logCustomEvent(job.getId(),
-                        getTranslation("jobsummary.history.manualcomplete.reason"),
-                        description, currentUser, JobHistoryType.STATUS_CHANGE);
-
-                Notification
-                        .show(getTranslation("jobsummary.notification.completed", job.getJobNumber()), 3000,
-                                Notification.Position.BOTTOM_END)
-                        .addThemeVariants(NotificationVariant.LUMO_SUCCESS);
-                getUI().ifPresent(ui -> ui.navigate("job_summary/" + job.getId().toHexString()));
-            } catch (Exception ex) {
-                Notification
-                        .show(getTranslation("jobsummary.notification.complete.error", ex.getMessage()), 5000,
-                                Notification.Position.BOTTOM_END)
-                        .addThemeVariants(NotificationVariant.LUMO_ERROR);
-            }
-        });
+        confirmButton.addClickListener(e -> confirm(reasonField));
 
         buttonBar.add(cancelButton, confirmButton);
         content.add(buttonBar);
+
+        loadSelectedServicesFromJob();
+    }
+
+    private VerticalLayout createRouteSection() {
+        VerticalLayout routeBox = new VerticalLayout();
+        routeBox.setPadding(true);
+        routeBox.setSpacing(true);
+        routeBox.setWidthFull();
+        routeBox.getStyle().set("border", "1px solid var(--lumo-primary-color-50pct)");
+        routeBox.getStyle().set("border-radius", "var(--lumo-border-radius-m)");
+        routeBox.getStyle().set("background-color", "var(--lumo-primary-color-10pct)");
+        routeBox.addClassName("route-card");
+
+        H3 routeTitle = new H3(getTranslation("addjob.route.title"));
+        routeTitle.getStyle().set("margin", "0");
+        routeTitle.getStyle().set("color", "var(--lumo-primary-text-color)");
+
+        HorizontalLayout distanceRow = new HorizontalLayout();
+        distanceRow.setWidthFull();
+        distanceRow.setJustifyContentMode(FlexComponent.JustifyContentMode.BETWEEN);
+        distanceRow.setAlignItems(FlexComponent.Alignment.CENTER);
+        Span distanceLabel = new Span(getTranslation("addjob.route.distance") + ":");
+        Span distanceValue = new Span(formatDistance(job.getRouteDistanceKm()));
+        distanceValue.getStyle().set("font-weight", "bold");
+        distanceValue.getStyle().set("font-size", "var(--lumo-font-size-l)");
+        distanceValue.getStyle().set("color", "var(--lumo-primary-text-color)");
+        distanceRow.add(distanceLabel, distanceValue);
+
+        HorizontalLayout durationRow = new HorizontalLayout();
+        durationRow.setWidthFull();
+        durationRow.setJustifyContentMode(FlexComponent.JustifyContentMode.BETWEEN);
+        durationRow.setAlignItems(FlexComponent.Alignment.CENTER);
+        Span durationLabel = new Span(getTranslation("addjob.route.duration") + ":");
+        Span durationValue = new Span(formatDuration(job.getRouteDurationSeconds()));
+        durationValue.getStyle().set("font-weight", "bold");
+        durationValue.getStyle().set("color", "var(--lumo-secondary-text-color)");
+        durationRow.add(durationLabel, durationValue);
+
+        routeBox.add(routeTitle, distanceRow, durationRow);
+        return routeBox;
+    }
+
+    private VerticalLayout createManualRouteSection() {
+        VerticalLayout box = new VerticalLayout();
+        box.setPadding(true);
+        box.setSpacing(true);
+        box.setWidthFull();
+        box.getStyle().set("border", "1px solid var(--lumo-primary-color-50pct)");
+        box.getStyle().set("border-radius", "var(--lumo-border-radius-m)");
+        box.getStyle().set("background-color", "var(--lumo-primary-color-10pct)");
+        box.addClassName("route-card");
+
+        H3 title = new H3(getTranslation("addjob.route.title"));
+        title.getStyle().set("margin", "0");
+        title.getStyle().set("color", "var(--lumo-primary-text-color)");
+
+        NumberField distanceField = new NumberField(getTranslation("addjob.route.distance.km"));
+        distanceField.setMin(0);
+        distanceField.setStep(0.1);
+        distanceField.setPlaceholder(getTranslation("addjob.route.distance.placeholder"));
+        distanceField.setWidthFull();
+
+        IntegerField hoursField = new IntegerField(getTranslation("jobmanualcomplete.route.hours"));
+        hoursField.setMin(0);
+        hoursField.setStepButtonsVisible(true);
+        hoursField.setWidthFull();
+
+        IntegerField minutesField = new IntegerField(getTranslation("jobmanualcomplete.route.minutes"));
+        minutesField.setMin(0);
+        minutesField.setMax(59);
+        minutesField.setStepButtonsVisible(true);
+        minutesField.setWidthFull();
+
+        if (manualDurationSeconds != null && manualDurationSeconds > 0) {
+            hoursField.setValue(manualDurationSeconds / 3600);
+            minutesField.setValue((manualDurationSeconds % 3600) / 60);
+        }
+
+        distanceField.addValueChangeListener(e -> {
+            manualDistanceKm = e.getValue();
+            servicesGrid.getDataProvider().refreshAll();
+            updatePriceSummary();
+        });
+
+        Runnable recalcDuration = () -> {
+            Integer h = hoursField.getValue();
+            Integer m = minutesField.getValue();
+            int hours = h != null ? Math.max(0, h) : 0;
+            int minutes = m != null ? Math.max(0, Math.min(59, m)) : 0;
+            int total = hours * 3600 + minutes * 60;
+            manualDurationSeconds = total > 0 ? total : null;
+            servicesGrid.getDataProvider().refreshAll();
+            updatePriceSummary();
+        };
+        hoursField.addValueChangeListener(e -> recalcDuration.run());
+        minutesField.addValueChangeListener(e -> recalcDuration.run());
+
+        HorizontalLayout durationRow = new HorizontalLayout(hoursField, minutesField);
+        durationRow.setWidthFull();
+        durationRow.setSpacing(true);
+        hoursField.getStyle().set("flex", "1");
+        minutesField.getStyle().set("flex", "1");
+
+        Span hint = new Span(getTranslation("jobmanualcomplete.route.manual.hint"));
+        hint.getStyle().set("font-size", "var(--lumo-font-size-s)");
+        hint.getStyle().set("color", "var(--lumo-secondary-text-color)");
+        hint.getStyle().set("font-style", "italic");
+
+        box.add(title, distanceField, durationRow, hint);
+        return box;
+    }
+
+    private VerticalLayout createServicesSection() {
+        VerticalLayout section = new VerticalLayout();
+        section.setPadding(false);
+        section.setSpacing(true);
+        section.setWidthFull();
+
+        H3 title = new H3(getTranslation("addjob.services.title"));
+        title.getStyle().set("margin", "0");
+
+        servicesGrid = new Grid<>();
+        servicesGrid.setWidthFull();
+        servicesGrid.setHeight("250px");
+        servicesGrid.setItems(serviceRows);
+        servicesGrid.addClassName("data-grid");
+
+        servicesGrid.addColumn(row -> row.service != null ? row.service.getName() : "")
+                .setHeader(getTranslation("common.service")).setSortable(true);
+        servicesGrid.addColumn(row -> formatDeliveryStationLabel(
+                        row.selection != null ? row.selection.getDeliveryStationOrder() : null))
+                .setHeader(getTranslation("addjob.services.deliverystation")).setSortable(false);
+        servicesGrid.addColumn(row -> formatCalculationBasis(row.service))
+                .setHeader(getTranslation("addjob.services.calculation")).setSortable(true);
+        servicesGrid.addColumn(this::formatPrice).setHeader(getTranslation("common.price")).setSortable(false);
+        servicesGrid.addComponentColumn(row -> {
+            if (row.service != null && row.service.isMandatory()) {
+                return new Span("");
+            }
+            Button removeButton = new Button(new Icon(VaadinIcon.TRASH));
+            removeButton.addThemeVariants(ButtonVariant.LUMO_ERROR, ButtonVariant.LUMO_TERTIARY,
+                    ButtonVariant.LUMO_SMALL);
+            removeButton.addClickListener(e -> {
+                serviceRows.remove(row);
+                servicesGrid.getDataProvider().refreshAll();
+                updatePriceSummary();
+            });
+            return removeButton;
+        }).setHeader(getTranslation("common.actions")).setAutoWidth(true).setFlexGrow(0);
+
+        Div gridPanel = new Div(servicesGrid);
+        gridPanel.addClassNames("surface-panel", "data-grid-panel");
+        gridPanel.setWidthFull();
+
+        Button addButton = new Button(getTranslation("addjob.services.add"), new Icon(VaadinIcon.PLUS));
+        addButton.addThemeVariants(ButtonVariant.LUMO_PRIMARY);
+        addButton.addClickListener(e -> openAddServiceDialog());
+
+        section.add(title, gridPanel, addButton);
+        return section;
+    }
+
+    private VerticalLayout createSummarySection() {
+        VerticalLayout summary = new VerticalLayout();
+        summary.setPadding(true);
+        summary.setSpacing(true);
+        summary.setWidthFull();
+        summary.getStyle().set("border", "1px solid var(--lumo-contrast-20pct)");
+        summary.getStyle().set("border-radius", "var(--lumo-border-radius-m)");
+        summary.getStyle().set("background-color", "var(--lumo-contrast-5pct)");
+        summary.setDefaultHorizontalComponentAlignment(FlexComponent.Alignment.STRETCH);
+        summary.addClassName("summary-card");
+
+        H3 title = new H3(getTranslation("addjob.summary.title"));
+        title.getStyle().set("margin", "0");
+        summary.add(title);
+
+        Div priceTable = new Div();
+        priceTable.getStyle().set("width", "100%");
+
+        Div netRow = new Div();
+        netRow.getStyle().set("display", "flex").set("justify-content", "space-between").set("padding", "4px 0");
+        Span netLabel = new Span(getTranslation("addjob.summary.net") + ":");
+        netLabel.getStyle().set("padding-right", "8px");
+        netTotalLabel = new Span("0,00 €");
+        netTotalLabel.getStyle().set("font-weight", "bold").set("white-space", "nowrap");
+        netRow.add(netLabel, netTotalLabel);
+
+        Div grossRow = new Div();
+        grossRow.getStyle().set("display", "flex").set("justify-content", "space-between").set("padding", "4px 0");
+        Span grossLabel = new Span(getTranslation("addjob.summary.gross") + ":");
+        grossLabel.getStyle().set("padding-right", "8px").set("font-weight", "bold");
+        grossTotalLabel = new Span("0,00 €");
+        grossTotalLabel.getStyle().set("font-size", "var(--lumo-font-size-l)");
+        grossTotalLabel.getStyle().set("font-weight", "bold");
+        grossTotalLabel.getStyle().set("color", "var(--lumo-primary-text-color)").set("white-space", "nowrap");
+        grossRow.add(grossLabel, grossTotalLabel);
+
+        priceTable.add(netRow, grossRow);
+        summary.add(priceTable);
+        return summary;
+    }
+
+    private VerticalLayout createRemarkSection() {
+        VerticalLayout section = new VerticalLayout();
+        section.setPadding(false);
+        section.setSpacing(true);
+        section.setWidthFull();
+
+        H3 title = new H3(getTranslation("addjob.tasks.remark"));
+        title.getStyle().set("margin", "0");
+
+        remarkArea = new TextArea();
+        remarkArea.setPlaceholder(getTranslation("addjob.tasks.remark.placeholder"));
+        remarkArea.setWidthFull();
+        remarkArea.setMinHeight("120px");
+        if (job.getRemark() != null) {
+            remarkArea.setValue(job.getRemark());
+        }
+
+        section.add(title, remarkArea);
+        return section;
+    }
+
+    private void loadSelectedServicesFromJob() {
+        serviceRows.clear();
+
+        if (job.getSelectedServices() != null && !job.getSelectedServices().isEmpty()) {
+            for (JobServiceSelection selection : job.getSelectedServices()) {
+                if (selection.getServiceId() == null) {
+                    continue;
+                }
+                serviceRepository.findById(selection.getServiceId())
+                        .ifPresent(service -> serviceRows.add(new ServiceRow(service, selection)));
+            }
+        } else if (job.getServiceIds() != null && !job.getServiceIds().isEmpty()) {
+            for (String serviceId : job.getServiceIds()) {
+                serviceRepository.findById(serviceId)
+                        .ifPresent(service -> serviceRows.add(new ServiceRow(service, null)));
+            }
+        }
+
+        servicesGrid.getDataProvider().refreshAll();
+        updatePriceSummary();
+    }
+
+    private void openAddServiceDialog() {
+        Dialog dialog = DialogStylingHelper.createStyledDialog(getTranslation("addjob.services.dialog.title"), "720px");
+        dialog.setCloseOnOutsideClick(false);
+
+        VerticalLayout dialogContent = DialogStylingHelper.createContentLayout("620px");
+
+        User currentUser = securityService.getCurrentDatabaseUser();
+        List<Service> availableServices = currentUser != null
+                ? serviceRepository.findByUserId(currentUser.getId().toString())
+                : List.of();
+
+        ComboBox<Service> serviceCombo = new ComboBox<>(getTranslation("common.service"));
+        serviceCombo.setWidthFull();
+        serviceCombo.setItems(availableServices);
+        serviceCombo.setItemLabelGenerator(service -> {
+            if (service.getCalculationBasis() == Service.CalculationBasis.FLAT_RATE
+                    && service.getEffectivePrice() != null) {
+                return service.getName() + " (" + service.getEffectivePrice().setScale(2, RoundingMode.HALF_UP) + " €)";
+            }
+            return service.getName();
+        });
+        serviceCombo.setPlaceholder(getTranslation("addjob.services.dialog.placeholder"));
+        serviceCombo.setRequired(true);
+
+        List<Integer> stationOrders = availableDeliveryStationOrders();
+        ComboBox<Integer> stationCombo = new ComboBox<>(getTranslation("addjob.services.deliverystation"));
+        stationCombo.setWidthFull();
+        stationCombo.setRequired(true);
+        stationCombo.setRequiredIndicatorVisible(true);
+        stationCombo.setItems(stationOrders);
+        stationCombo.setItemLabelGenerator(this::buildDeliveryStationSelectionLabel);
+        stationCombo.setPlaceholder(getTranslation("addjob.services.dialog.station.placeholder"));
+        if (!stationOrders.isEmpty()) {
+            stationCombo.setValue(0);
+        }
+
+        dialogContent.add(serviceCombo, stationCombo);
+
+        Button cancel = new Button(getTranslation("button.cancel"), e -> dialog.close());
+        cancel.addThemeVariants(ButtonVariant.LUMO_TERTIARY);
+
+        Button add = new Button(getTranslation("addjob.services.dialog.add"), e -> {
+            Service service = serviceCombo.getValue();
+            Integer stationOrder = stationCombo.getValue();
+            if (service == null || stationOrder == null) {
+                return;
+            }
+            JobServiceSelection selection = new JobServiceSelection();
+            selection.setServiceId(service.getId());
+            selection.setDeliveryStationOrder(stationOrder);
+            selection.setRouteDistanceKm(manualDistanceKm);
+            selection.setRouteDurationSeconds(manualDurationSeconds);
+            serviceRows.add(new ServiceRow(service, selection));
+            servicesGrid.getDataProvider().refreshAll();
+            updatePriceSummary();
+            dialog.close();
+        });
+        add.addThemeVariants(ButtonVariant.LUMO_PRIMARY);
+
+        dialog.add(DialogStylingHelper.wrapContent(dialogContent));
+        dialog.getFooter().add(cancel, add);
+        dialog.open();
+    }
+
+    private List<Integer> availableDeliveryStationOrders() {
+        List<Integer> orders = new ArrayList<>();
+        if (job.getDeliveryStations() != null) {
+            for (int i = 0; i < job.getDeliveryStations().size(); i++) {
+                orders.add(i);
+            }
+        }
+        return orders;
+    }
+
+    private String buildDeliveryStationSelectionLabel(Integer order) {
+        if (order == null || job.getDeliveryStations() == null || order < 0
+                || order >= job.getDeliveryStations().size()) {
+            return "-";
+        }
+        DeliveryStation station = job.getDeliveryStations().get(order);
+        StringBuilder label = new StringBuilder(getTranslation("addjob.station.delivery", order + 1));
+        if (station.getCity() != null && !station.getCity().isBlank()) {
+            label.append(" - ").append(station.getCity());
+        } else if (station.getCompany() != null && !station.getCompany().isBlank()) {
+            label.append(" - ").append(station.getCompany());
+        }
+        return label.toString();
+    }
+
+    private String formatDeliveryStationLabel(Integer order) {
+        if (order == null || order < 0) {
+            return "-";
+        }
+        return getTranslation("addjob.station.delivery", order + 1);
+    }
+
+    private String formatCalculationBasis(Service service) {
+        if (service == null || service.getCalculationBasis() == null) {
+            return "";
+        }
+        return switch (service.getCalculationBasis()) {
+            case DISTANCE -> getTranslation("addjob.services.basis.distance");
+            case TIME -> getTranslation("addjob.services.basis.time");
+            case FLAT_RATE -> getTranslation("addjob.services.basis.flatrate");
+        };
+    }
+
+    private String formatPrice(ServiceRow row) {
+        Service service = row.service;
+        if (service == null || service.getCalculationBasis() == null) {
+            return "";
+        }
+        BigDecimal price = calculateServicePrice(row);
+        if (price != null && price.compareTo(BigDecimal.ZERO) > 0) {
+            return price.setScale(2, RoundingMode.HALF_UP) + " €";
+        }
+        if (service.getCalculationBasis() == Service.CalculationBasis.DISTANCE && service.getPricePerKilometer() != null
+                && routeDistanceFor(row.selection) == null) {
+            return service.getPricePerKilometer().setScale(2, RoundingMode.HALF_UP) + " €/km ("
+                    + getTranslation("addjob.services.route.missing") + ")";
+        }
+        if (service.getCalculationBasis() == Service.CalculationBasis.TIME && service.getPricePer15Minutes() != null
+                && routeDurationFor(row.selection) == null) {
+            return service.getPricePer15Minutes().setScale(2, RoundingMode.HALF_UP) + " €/15 Min. ("
+                    + getTranslation("addjob.services.route.missing") + ")";
+        }
+        return service.getEffectivePrice() != null
+                ? service.getEffectivePrice().setScale(2, RoundingMode.HALF_UP) + " €"
+                : "";
+    }
+
+    private BigDecimal calculateServicePrice(ServiceRow row) {
+        Service service = row.service;
+        if (service == null || service.getCalculationBasis() == null) {
+            return BigDecimal.ZERO;
+        }
+        switch (service.getCalculationBasis()) {
+            case FLAT_RATE:
+                return service.getPrice() != null ? service.getPrice() : BigDecimal.ZERO;
+            case DISTANCE: {
+                Double km = routeDistanceFor(row.selection);
+                if (service.getPricePerKilometer() != null && km != null && km > 0) {
+                    return service.getPricePerKilometer().multiply(BigDecimal.valueOf(km));
+                }
+                return BigDecimal.ZERO;
+            }
+            case TIME: {
+                Integer seconds = routeDurationFor(row.selection);
+                if (service.getPricePer15Minutes() != null && seconds != null && seconds > 0) {
+                    int units = seconds / 900;
+                    if (seconds % 900 > 0) {
+                        units++;
+                    }
+                    return service.getPricePer15Minutes().multiply(BigDecimal.valueOf(units));
+                }
+                return BigDecimal.ZERO;
+            }
+            default:
+                return BigDecimal.ZERO;
+        }
+    }
+
+    private Double routeDistanceFor(JobServiceSelection selection) {
+        if (selection != null && selection.getRouteDistanceKm() != null) {
+            return selection.getRouteDistanceKm();
+        }
+        return manualDistanceKm;
+    }
+
+    private Integer routeDurationFor(JobServiceSelection selection) {
+        if (selection != null && selection.getRouteDurationSeconds() != null) {
+            return selection.getRouteDurationSeconds();
+        }
+        return manualDurationSeconds;
+    }
+
+    private void updatePriceSummary() {
+        BigDecimal net = BigDecimal.ZERO;
+        for (ServiceRow row : serviceRows) {
+            net = net.add(calculateServicePrice(row));
+        }
+        BigDecimal gross = net.add(net.multiply(vatRate));
+        netTotalLabel.setText(formatAmount(net));
+        grossTotalLabel.setText(formatAmount(gross));
+    }
+
+    private String formatAmount(BigDecimal amount) {
+        return amount.setScale(2, RoundingMode.HALF_UP).toString().replace(".", ",") + " €";
+    }
+
+    private String formatDistance(Double km) {
+        if (km == null) {
+            return "-";
+        }
+        return String.format(Locale.GERMANY, "%.1f km", km);
+    }
+
+    private String formatDuration(Integer seconds) {
+        if (seconds == null || seconds <= 0) {
+            return "-";
+        }
+        int hours = seconds / 3600;
+        int minutes = (seconds % 3600) / 60;
+        if (hours > 0) {
+            return String.format("%d Std. %d Min.", hours, minutes);
+        }
+        return String.format("%d Min.", minutes);
+    }
+
+    private void confirm(TextArea reasonField) {
+        String reason = reasonField.getValue();
+        if (reason == null || reason.trim().isEmpty()) {
+            reasonField.setInvalid(true);
+            reasonField.setErrorMessage(getTranslation("jobsummary.dialog.manualcomplete.reason.required"));
+            return;
+        }
+
+        try {
+            JobStatus oldStatus = job.getStatus();
+
+            List<JobServiceSelection> selections = new ArrayList<>();
+            for (ServiceRow row : serviceRows) {
+                if (row.service == null) {
+                    continue;
+                }
+                JobServiceSelection selection = row.selection != null ? row.selection : new JobServiceSelection();
+                selection.setServiceId(row.service.getId());
+                if (selection.getDeliveryStationOrder() == null && row.selection != null) {
+                    selection.setDeliveryStationOrder(row.selection.getDeliveryStationOrder());
+                }
+                selections.add(selection);
+            }
+            job.setSelectedServices(selections);
+
+            String remark = remarkArea.getValue();
+            job.setRemark(remark != null && !remark.isBlank() ? remark.trim() : null);
+
+            if (job.getRouteDistanceKm() == null || job.getRouteDistanceKm() <= 0) {
+                job.setRouteDistanceKm(manualDistanceKm);
+                job.setRouteDurationSeconds(manualDurationSeconds);
+            }
+
+            job.setStatus(JobStatus.COMPLETED);
+            job.setUpdatedAt(LocalDateTime.now());
+            jobRepository.save(job);
+
+            String currentUser = securityService.getCurrentUsername();
+            jobHistoryService.logStatusChange(job, oldStatus, JobStatus.COMPLETED, currentUser);
+
+            String description = String.format("Auftrag manuell beendet von %s. Begründung: %s", currentUser,
+                    reason.trim());
+            jobHistoryService.logCustomEvent(job.getId(), getTranslation("jobsummary.history.manualcomplete.reason"),
+                    description, currentUser, JobHistoryType.STATUS_CHANGE);
+
+            Notification
+                    .show(getTranslation("jobsummary.notification.completed", job.getJobNumber()), 3000,
+                            Notification.Position.BOTTOM_END)
+                    .addThemeVariants(NotificationVariant.LUMO_SUCCESS);
+            getUI().ifPresent(ui -> ui.navigate("job_summary/" + job.getId().toHexString()));
+        } catch (Exception ex) {
+            Notification
+                    .show(getTranslation("jobsummary.notification.complete.error", ex.getMessage()), 5000,
+                            Notification.Position.BOTTOM_END)
+                    .addThemeVariants(NotificationVariant.LUMO_ERROR);
+        }
     }
 }

backend/src/main/java/de/assecutor/votianlt/pages/view/ShowJobsView.java

@@ -50,6 +50,7 @@ public class ShowJobsView extends VerticalLayout implements HasDynamicTitle {
     private final SecurityService securityService;
     private final ClientConnectionService clientConnectionService;
     private final MessagingPublisher messagingPublisher;
+    private final CustomerInvoiceRepository customerInvoiceRepository;
     private final Grid<Job> grid = new Grid<>(Job.class, false);
 
     @Autowired
@@ -61,6 +62,7 @@ public class ShowJobsView extends VerticalLayout implements HasDynamicTitle {
         this.securityService = securityService;
         this.clientConnectionService = clientConnectionService;
         this.messagingPublisher = messagingPublisher;
+        this.customerInvoiceRepository = customerInvoiceRepository;
         setSizeFull();
         setPadding(true);
         setSpacing(true);

backend/src/main/java/de/assecutor/votianlt/repository/CustomerInvoiceRepository.java

@@ -1,6 +1,7 @@
 package de.assecutor.votianlt.repository;
 
 import de.assecutor.votianlt.model.invoices.CustomerInvoice;
+import de.assecutor.votianlt.model.invoices.InvoiceStatus;
 import org.springframework.data.mongodb.repository.MongoRepository;
 import org.springframework.stereotype.Repository;
 
@@ -13,4 +14,13 @@ public interface CustomerInvoiceRepository extends MongoRepository<CustomerInvoi
     Optional<CustomerInvoice> findByJobId(String jobId);
 
     List<CustomerInvoice> findByUserId(String userId);
+
+    /** Liefert die – höchstens eine – aktive (nicht stornierte) Rechnung mit dieser Nummer (R-11). */
+    Optional<CustomerInvoice> findByInvoiceNumberAndStatusNot(String invoiceNumber, InvoiceStatus status);
+
+    /** Alle Folgebelege (Storno, Korrektur, Ersatzrechnung), die auf diese Originalrechnung verweisen. */
+    List<CustomerInvoice> findByOriginalInvoiceId(String originalInvoiceId);
+
+    /** Findet alle Rechnungen ohne expliziten Status — wird für die Bestandsdatenmigration genutzt. */
+    List<CustomerInvoice> findByStatusIsNull();
 }

backend/src/main/java/de/assecutor/votianlt/repository/InvoiceNumberReservationRepository.java

@@ -0,0 +1,23 @@
+package de.assecutor.votianlt.repository;
+
+import de.assecutor.votianlt.model.invoices.InvoiceNumberReservation;
+import de.assecutor.votianlt.model.invoices.InvoiceNumberReservationStatus;
+import org.bson.types.ObjectId;
+import org.springframework.data.mongodb.repository.MongoRepository;
+import org.springframework.stereotype.Repository;
+
+import java.util.List;
+import java.util.Optional;
+
+@Repository
+public interface InvoiceNumberReservationRepository extends MongoRepository<InvoiceNumberReservation, ObjectId> {
+
+    Optional<InvoiceNumberReservation> findByUserIdAndNumber(ObjectId userId, String number);
+
+    Optional<InvoiceNumberReservation> findByUserIdAndSequence(ObjectId userId, long sequence);
+
+    List<InvoiceNumberReservation> findByUserIdOrderBySequenceAsc(ObjectId userId);
+
+    List<InvoiceNumberReservation> findByUserIdAndStatusOrderBySequenceAsc(ObjectId userId,
+            InvoiceNumberReservationStatus status);
+}

backend/src/main/java/de/assecutor/votianlt/security/InvoiceRoles.java

@@ -0,0 +1,26 @@
+package de.assecutor.votianlt.security;
+
+/**
+ * Rollen für die Bearbeitung von Rechnungen gemäß R-40 bis R-42.
+ *
+ * Die Rollen sind als Konstanten definiert und werden in der bestehenden
+ * {@link de.assecutor.votianlt.model.User#getRoles()}-Sammlung als String hinterlegt.
+ *
+ * Backwards-compat: Bestehende Nutzer haben keine dieser Rollen — die
+ * {@code USER}-Rolle bleibt vollumfänglich berechtigt, sofern keine speziellen
+ * Rechnungsrollen explizit zugewiesen sind.
+ */
+public final class InvoiceRoles {
+
+    /** Erstellt Entwürfe und stellt Rechnungen aus. */
+    public static final String CREATOR = "INVOICE_CREATOR";
+    /** Prüft Entwürfe und Folgebelege vor Freigabe. */
+    public static final String REVIEWER = "INVOICE_REVIEWER";
+    /** Gibt Storno- und Berichtigungsbelege frei (R-42). */
+    public static final String APPROVER = "INVOICE_APPROVER";
+    /** Erfasst Zahlungen und buchhalterische Vorgänge (R-25). */
+    public static final String ACCOUNTANT = "INVOICE_ACCOUNTANT";
+
+    private InvoiceRoles() {
+    }
+}

backend/src/main/java/de/assecutor/votianlt/service/AesGcmCipher.java

@@ -0,0 +1,71 @@
+package de.assecutor.votianlt.service;
+
+import javax.crypto.Cipher;
+import javax.crypto.spec.GCMParameterSpec;
+import javax.crypto.spec.SecretKeySpec;
+import java.nio.ByteBuffer;
+import java.security.MessageDigest;
+import java.security.SecureRandom;
+
+/**
+ * Symmetrische AES-256-GCM-Verschlüsselung mit Master-Key-Ableitung über SHA-256.
+ *
+ * Format der erzeugten Bytes: {@code IV (12 Byte) || Ciphertext+Tag (16 Byte Tag)}.
+ * Der IV wird pro Verschlüsselung neu zufällig erzeugt; ein Master-Key liefert
+ * deterministisch denselben AES-Schlüssel.
+ *
+ * Nicht für hochfrequente Krypto-Operationen optimiert — bewusst minimal gehalten.
+ */
+final class AesGcmCipher {
+
+    private static final String TRANSFORMATION = "AES/GCM/NoPadding";
+    private static final int IV_LENGTH = 12;
+    private static final int TAG_LENGTH_BITS = 128;
+
+    private final SecretKeySpec key;
+    private final SecureRandom random = new SecureRandom();
+
+    AesGcmCipher(String masterKey) {
+        if (masterKey == null || masterKey.length() < 16) {
+            throw new IllegalArgumentException("Master-Key muss mindestens 16 Zeichen lang sein.");
+        }
+        try {
+            byte[] derived = MessageDigest.getInstance("SHA-256").digest(masterKey.getBytes("UTF-8"));
+            this.key = new SecretKeySpec(derived, "AES");
+        } catch (Exception ex) {
+            throw new IllegalStateException("Master-Key konnte nicht abgeleitet werden.", ex);
+        }
+    }
+
+    byte[] encrypt(byte[] plaintext) {
+        try {
+            byte[] iv = new byte[IV_LENGTH];
+            random.nextBytes(iv);
+            Cipher cipher = Cipher.getInstance(TRANSFORMATION);
+            cipher.init(Cipher.ENCRYPT_MODE, key, new GCMParameterSpec(TAG_LENGTH_BITS, iv));
+            byte[] ciphertext = cipher.doFinal(plaintext);
+            return ByteBuffer.allocate(IV_LENGTH + ciphertext.length).put(iv).put(ciphertext).array();
+        } catch (Exception ex) {
+            throw new IllegalStateException("Verschlüsselung fehlgeschlagen: " + ex.getMessage(), ex);
+        }
+    }
+
+    byte[] decrypt(byte[] ivAndCiphertext) {
+        if (ivAndCiphertext == null || ivAndCiphertext.length < IV_LENGTH + 16) {
+            throw new IllegalArgumentException("Ciphertext zu kurz.");
+        }
+        try {
+            ByteBuffer buffer = ByteBuffer.wrap(ivAndCiphertext);
+            byte[] iv = new byte[IV_LENGTH];
+            buffer.get(iv);
+            byte[] ciphertext = new byte[buffer.remaining()];
+            buffer.get(ciphertext);
+
+            Cipher cipher = Cipher.getInstance(TRANSFORMATION);
+            cipher.init(Cipher.DECRYPT_MODE, key, new GCMParameterSpec(TAG_LENGTH_BITS, iv));
+            return cipher.doFinal(ciphertext);
+        } catch (Exception ex) {
+            throw new IllegalStateException("Entschlüsselung fehlgeschlagen: " + ex.getMessage(), ex);
+        }
+    }
+}

backend/src/main/java/de/assecutor/votianlt/service/CustomerInvoiceService.java

@@ -921,4 +921,181 @@ public class CustomerInvoiceService {
         return input.replace("&", "&amp;").replace("<", "&lt;").replace(">", "&gt;").replace("\"", "&quot;")
                 .replace("'", "&#x27;");
     }
+
+    /**
+     * Erzeugt ein einfaches PDF für einen Stornobeleg gemäß R-19.
+     * Verweist eindeutig auf die Originalrechnung (Nummer + Datum) und stellt die
+     * Beträge als negative Werte dar.
+     */
+    public byte[] generateCancellationPdf(de.assecutor.votianlt.model.invoices.CustomerInvoice original,
+            String cancellationNumber, java.time.LocalDate cancellationDate, String reason) throws Exception {
+        return generateCorrectionDocumentPdf("STORNORECHNUNG", original, cancellationNumber, cancellationDate, reason,
+                null, true);
+    }
+
+    /**
+     * Erzeugt ein einfaches PDF für einen Berichtigungsbeleg gemäß R-13/R-14.
+     * Verweist eindeutig auf die Originalrechnung und beschreibt die berichtigten Angaben.
+     */
+    public byte[] generateCorrectionPdf(de.assecutor.votianlt.model.invoices.CustomerInvoice original,
+            String correctionNumber, java.time.LocalDate correctionDate, String reason, String correctedFields)
+            throws Exception {
+        return generateCorrectionDocumentPdf("RECHNUNGSBERICHTIGUNG", original, correctionNumber, correctionDate,
+                reason, correctedFields, false);
+    }
+
+    private byte[] generateCorrectionDocumentPdf(String documentLabel,
+            de.assecutor.votianlt.model.invoices.CustomerInvoice original, String number,
+            java.time.LocalDate documentDate, String reason, String correctedFields, boolean negateAmounts)
+            throws Exception {
+        java.time.LocalDate effectiveDate = documentDate != null ? documentDate : java.time.LocalDate.now();
+        java.time.format.DateTimeFormatter dateFmt = java.time.format.DateTimeFormatter.ofPattern("dd.MM.yyyy",
+                Locale.GERMANY);
+
+        BigDecimal net = negateAmounts ? negateOrZero(original.getNetAmount()) : safeAmount(original.getNetAmount());
+        BigDecimal vat = negateAmounts ? negateOrZero(original.getVatAmount()) : safeAmount(original.getVatAmount());
+        BigDecimal total = negateAmounts ? negateOrZero(original.getTotalAmount())
+                : safeAmount(original.getTotalAmount());
+
+        StringBuilder html = new StringBuilder();
+        html.append("<!DOCTYPE html><html><head><meta charset='UTF-8'><style>");
+        html.append("@page { size: A4; margin: 20mm 18mm 20mm 18mm; }");
+        html.append("body { font-family: Arial, sans-serif; font-size: 11pt; color: #222; }");
+        html.append("h1 { font-size: 18pt; letter-spacing: 0.05em; margin: 0 0 8pt 0; }");
+        html.append("h2 { font-size: 13pt; margin: 18pt 0 6pt 0; }");
+        html.append(".doc-number { font-size: 11pt; color: #555; }");
+        html.append(".section { margin-top: 14pt; }");
+        html.append(".reference { background: #f6f6f6; border-left: 3px solid #888; padding: 8pt 12pt; }");
+        html.append(".reason { background: #fff8e6; border-left: 3px solid #d9a300; padding: 8pt 12pt; }");
+        html.append("table.amounts { width: 60%; margin-left: 40%; border-collapse: collapse; margin-top: 10pt; }");
+        html.append("table.amounts td { padding: 3pt 6pt; }");
+        html.append("table.amounts td.value { text-align: right; }");
+        html.append("table.amounts tr.total td { font-weight: bold; border-top: 1px solid #333; }");
+        html.append(".addresses { width: 100%; margin-top: 14pt; }");
+        html.append(".addresses td { width: 50%; vertical-align: top; }");
+        html.append(".muted { color: #666; font-size: 9pt; }");
+        html.append("</style></head><body>");
+
+        html.append("<h1>").append(escapeHtml(documentLabel)).append("</h1>");
+        html.append("<div class='doc-number'>Beleg-Nr.: ")
+                .append(escapeHtml(safe(number)))
+                .append(" &nbsp;·&nbsp; Datum: ").append(escapeHtml(effectiveDate.format(dateFmt)))
+                .append("</div>");
+
+        // Sender / Empfänger
+        html.append("<table class='addresses'><tr><td>");
+        html.append("<strong>Aussteller</strong><br/>");
+        html.append(formatAddressBlock(original.getSenderName(), original.getSenderAddress(),
+                original.getSenderPostcode(), original.getSenderCity(), original.getSenderCountry()));
+        if (original.getSenderTaxNumber() != null && !original.getSenderTaxNumber().isBlank()) {
+            html.append("<div class='muted'>Steuernr.: ").append(escapeHtml(original.getSenderTaxNumber()))
+                    .append("</div>");
+        }
+        if (original.getSenderVatId() != null && !original.getSenderVatId().isBlank()) {
+            html.append("<div class='muted'>USt-IdNr.: ").append(escapeHtml(original.getSenderVatId()))
+                    .append("</div>");
+        }
+        html.append("</td><td>");
+        html.append("<strong>Empfänger</strong><br/>");
+        html.append(formatAddressBlock(
+                firstNonBlank(original.getRecipientCompany(), original.getRecipientName()),
+                original.getRecipientAddress(), original.getRecipientPostcode(), original.getRecipientCity(),
+                original.getRecipientCountry()));
+        html.append("</td></tr></table>");
+
+        // Eindeutige Referenz auf Originalrechnung (R-13/R-19/R-28)
+        html.append("<div class='section reference'>");
+        html.append("<strong>Bezug:</strong> ");
+        html.append("Diese ").append(escapeHtml(documentLabel.toLowerCase(Locale.GERMANY))).append(" bezieht sich ");
+        html.append("eindeutig auf die Rechnung <strong>")
+                .append(escapeHtml(safe(original.getInvoiceNumber()))).append("</strong>");
+        if (original.getInvoiceDate() != null) {
+            html.append(" vom ").append(escapeHtml(original.getInvoiceDate().format(dateFmt)));
+        }
+        html.append(".");
+        html.append("</div>");
+
+        if (correctedFields != null && !correctedFields.isBlank()) {
+            html.append("<div class='section'><h2>Berichtigte Angaben</h2>");
+            html.append("<div>").append(escapeHtml(correctedFields).replace("\n", "<br/>")).append("</div></div>");
+        }
+
+        if (reason != null && !reason.isBlank()) {
+            html.append("<div class='section reason'><strong>Grund:</strong> ")
+                    .append(escapeHtml(reason).replace("\n", "<br/>")).append("</div>");
+        }
+
+        html.append("<h2>Beträge</h2>");
+        html.append("<table class='amounts'>");
+        html.append("<tr><td>Nettobetrag</td><td class='value'>").append(formatCurrency(net)).append("</td></tr>");
+        if (original.getVatRate() != null) {
+            BigDecimal vatPct = original.getVatRate().multiply(new BigDecimal("100"))
+                    .setScale(2, java.math.RoundingMode.HALF_UP).stripTrailingZeros();
+            if (vatPct.scale() < 0) {
+                vatPct = vatPct.setScale(0);
+            }
+            html.append("<tr><td>zzgl. ").append(vatPct.toPlainString().replace('.', ','))
+                    .append("% USt</td><td class='value'>").append(formatCurrency(vat)).append("</td></tr>");
+        } else {
+            html.append("<tr><td>zzgl. USt</td><td class='value'>").append(formatCurrency(vat)).append("</td></tr>");
+        }
+        html.append("<tr class='total'><td>Gesamtbetrag</td><td class='value'>").append(formatCurrency(total))
+                .append("</td></tr>");
+        html.append("</table>");
+
+        html.append("<div class='section muted'>");
+        html.append("Hinweis: Dieser Beleg ersetzt die Originalrechnung nicht. Original und ");
+        html.append(escapeHtml(documentLabel.toLowerCase(Locale.GERMANY)));
+        html.append(" sind gemeinsam aufzubewahren.");
+        html.append("</div>");
+
+        html.append("</body></html>");
+
+        return generatePdfFromHtmlString(html.toString());
+    }
+
+    private BigDecimal safeAmount(BigDecimal value) {
+        return value != null ? value : BigDecimal.ZERO;
+    }
+
+    private BigDecimal negateOrZero(BigDecimal value) {
+        return value != null ? value.negate() : BigDecimal.ZERO;
+    }
+
+    private String formatAddressBlock(String name, String street, String postcode, String city, String country) {
+        StringBuilder sb = new StringBuilder();
+        if (name != null && !name.isBlank()) {
+            sb.append(escapeHtml(name)).append("<br/>");
+        }
+        if (street != null && !street.isBlank()) {
+            sb.append(escapeHtml(street)).append("<br/>");
+        }
+        String line = String.join(" ", filterBlanks(postcode, city)).trim();
+        if (!line.isEmpty()) {
+            sb.append(escapeHtml(line)).append("<br/>");
+        }
+        if (country != null && !country.isBlank()) {
+            sb.append(escapeHtml(country));
+        }
+        return sb.toString();
+    }
+
+    private java.util.List<String> filterBlanks(String... values) {
+        java.util.List<String> out = new java.util.ArrayList<>();
+        for (String v : values) {
+            if (v != null && !v.isBlank()) {
+                out.add(v);
+            }
+        }
+        return out;
+    }
+
+    private String firstNonBlank(String... values) {
+        for (String v : values) {
+            if (v != null && !v.isBlank()) {
+                return v;
+            }
+        }
+        return "";
+    }
 }

backend/src/main/java/de/assecutor/votianlt/service/InvoiceComplianceException.java

@@ -0,0 +1,35 @@
+package de.assecutor.votianlt.service;
+
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * Wird geworfen, wenn eine Rechnung beim Festschreiben gegen Pflichtangaben
+ * nach § 14 UStG bzw. interne Konsistenzregeln verstößt. Die Verstöße werden
+ * gesammelt geliefert, damit der Anwender alle Korrekturen in einem Schritt
+ * durchführen kann statt jeden Fehler einzeln zu beheben.
+ */
+public class InvoiceComplianceException extends InvoiceLifecycleException {
+
+    private final List<String> violations;
+
+    public InvoiceComplianceException(List<String> violations) {
+        super(buildMessage(violations));
+        this.violations = List.copyOf(violations);
+    }
+
+    public List<String> getViolations() {
+        return Collections.unmodifiableList(violations);
+    }
+
+    private static String buildMessage(List<String> violations) {
+        if (violations == null || violations.isEmpty()) {
+            return "Die Rechnung erfüllt die gesetzlichen Pflichtangaben nicht.";
+        }
+        StringBuilder sb = new StringBuilder("Die Rechnung kann nicht festgeschrieben werden — folgende Pflichtangaben fehlen oder sind inkonsistent:");
+        for (String violation : violations) {
+            sb.append("\n  • ").append(violation);
+        }
+        return sb.toString();
+    }
+}

backend/src/main/java/de/assecutor/votianlt/service/InvoiceComplianceValidator.java

@@ -0,0 +1,189 @@
+package de.assecutor.votianlt.service;
+
+import de.assecutor.votianlt.model.invoices.CustomerInvoice;
+import de.assecutor.votianlt.model.invoices.CustomerInvoiceItem;
+import de.assecutor.votianlt.model.invoices.InvoiceType;
+import org.springframework.stereotype.Service;
+
+import java.math.BigDecimal;
+import java.math.RoundingMode;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Prüft eine {@link CustomerInvoice} auf die Pflichtangaben nach § 14 UStG
+ * sowie auf interne Konsistenz (Beträge, Items). Wird vor jeder Festschreibung
+ * (Übergang DRAFT → ISSUED) aufgerufen; eine festgeschriebene Rechnung darf
+ * keine Pflichtfeld-Lücken mehr haben, da sie nach R-08 nicht mehr direkt
+ * änderbar ist.
+ *
+ * Nicht abgedeckt (bewusst):
+ * <ul>
+ *   <li>Lückenlose Rechnungsnummer-Vergabe (separater Block).</li>
+ *   <li>Online-Validierung der USt-IdNr beim Bzst (separater Block).</li>
+ *   <li>Storno-/Korrekturbelege — diese haben eigene Beleg-Regeln (negierte Beträge,
+ *       Pflicht-Verweis auf Originalrechnung), die hier nicht greifen.</li>
+ * </ul>
+ *
+ * Toleranz für Beträge: 1 Cent. Damit fängt der Validator typische Rundungs-
+ * differenzen aus dezimaler Arithmetik ab, ohne echte Inkonsistenzen zu schlucken.
+ */
+@Service
+public class InvoiceComplianceValidator {
+
+    private static final BigDecimal AMOUNT_TOLERANCE = new BigDecimal("0.01");
+
+    /**
+     * Wirft {@link InvoiceComplianceException} mit allen gefundenen Verstößen,
+     * wenn die Rechnung nicht festschreibungsreif ist. Andernfalls passiert nichts.
+     */
+    public void validateForIssuance(CustomerInvoice invoice) {
+        if (invoice == null) {
+            throw new IllegalArgumentException("Rechnung darf nicht null sein.");
+        }
+        if (invoice.getType() != null && invoice.getType() != InvoiceType.INVOICE) {
+            // Storno/Korrektur folgen anderen Regeln und werden hier nicht geprüft.
+            return;
+        }
+        List<String> violations = collectViolations(invoice);
+        if (!violations.isEmpty()) {
+            throw new InvoiceComplianceException(violations);
+        }
+    }
+
+    private List<String> collectViolations(CustomerInvoice invoice) {
+        List<String> violations = new ArrayList<>();
+        checkInvoiceNumber(invoice, violations);
+        checkDates(invoice, violations);
+        checkSender(invoice, violations);
+        checkRecipient(invoice, violations);
+        checkItems(invoice, violations);
+        checkAmounts(invoice, violations);
+        checkVatNotices(invoice, violations);
+        return violations;
+    }
+
+    private void checkInvoiceNumber(CustomerInvoice invoice, List<String> violations) {
+        if (isBlank(invoice.getInvoiceNumber())) {
+            violations.add("Rechnungsnummer fehlt (§ 14 Abs. 4 Nr. 4 UStG).");
+        }
+    }
+
+    private void checkDates(CustomerInvoice invoice, List<String> violations) {
+        if (invoice.getInvoiceDate() == null) {
+            violations.add("Rechnungsdatum (Ausstellungsdatum) fehlt (§ 14 Abs. 4 Nr. 3 UStG).");
+        }
+        if (invoice.getDeliveryDate() == null) {
+            violations.add("Leistungsdatum fehlt (§ 14 Abs. 4 Nr. 6 UStG). "
+                    + "Bei zeitgleicher Leistung kann es dem Rechnungsdatum entsprechen — muss aber gesetzt sein.");
+        }
+    }
+
+    private void checkSender(CustomerInvoice invoice, List<String> violations) {
+        if (isBlank(invoice.getSenderName())) {
+            violations.add("Name des Leistenden (Absender) fehlt (§ 14 Abs. 4 Nr. 1 UStG).");
+        }
+        if (isBlank(invoice.getSenderAddress()) || isBlank(invoice.getSenderPostcode())
+                || isBlank(invoice.getSenderCity())) {
+            violations.add("Vollständige Anschrift des Leistenden (Straße, PLZ, Ort) fehlt (§ 14 Abs. 4 Nr. 1 UStG).");
+        }
+        if (isBlank(invoice.getSenderTaxNumber()) && isBlank(invoice.getSenderVatId())) {
+            violations.add("Steuernummer oder USt-IdNr des Leistenden fehlt (§ 14 Abs. 4 Nr. 2 UStG).");
+        }
+    }
+
+    private void checkRecipient(CustomerInvoice invoice, List<String> violations) {
+        if (isBlank(invoice.getRecipientName())) {
+            violations.add("Name des Leistungsempfängers fehlt (§ 14 Abs. 4 Nr. 1 UStG).");
+        }
+        if (isBlank(invoice.getRecipientAddress()) || isBlank(invoice.getRecipientPostcode())
+                || isBlank(invoice.getRecipientCity())) {
+            violations.add("Vollständige Anschrift des Leistungsempfängers (Straße, PLZ, Ort) fehlt "
+                    + "(§ 14 Abs. 4 Nr. 1 UStG).");
+        }
+    }
+
+    private void checkItems(CustomerInvoice invoice, List<String> violations) {
+        List<CustomerInvoiceItem> items = invoice.getItems();
+        if (items == null || items.isEmpty()) {
+            violations.add("Keine Positionen erfasst — Menge und Art der Leistung sind erforderlich "
+                    + "(§ 14 Abs. 4 Nr. 5 UStG).");
+            return;
+        }
+        for (int i = 0; i < items.size(); i++) {
+            CustomerInvoiceItem item = items.get(i);
+            int rowNumber = i + 1;
+            if (item == null) {
+                violations.add("Position " + rowNumber + ": leere Position.");
+                continue;
+            }
+            if (isBlank(item.getDescription())) {
+                violations.add("Position " + rowNumber + ": Bezeichnung der Leistung fehlt.");
+            }
+            if (item.getQuantity() == null || item.getQuantity().signum() <= 0) {
+                violations.add("Position " + rowNumber + ": Menge muss größer 0 sein.");
+            }
+            if (item.getUnitPrice() == null || item.getUnitPrice().signum() < 0) {
+                violations.add("Position " + rowNumber + ": Einzelpreis fehlt oder ist negativ.");
+            }
+        }
+    }
+
+    private void checkAmounts(CustomerInvoice invoice, List<String> violations) {
+        BigDecimal net = invoice.getNetAmount();
+        BigDecimal vat = invoice.getVatAmount();
+        BigDecimal total = invoice.getTotalAmount();
+        if (net == null || vat == null || total == null) {
+            violations.add("Beträge unvollständig: Netto, Steuerbetrag und Bruttobetrag müssen ausgewiesen sein "
+                    + "(§ 14 Abs. 4 Nr. 7 + 8 UStG).");
+            return;
+        }
+        if (net.add(vat).subtract(total).abs().compareTo(AMOUNT_TOLERANCE) > 0) {
+            violations.add("Bruttobetrag passt nicht zu Netto + Steuerbetrag (Differenz > 1 Cent).");
+        }
+        if (invoice.getItems() != null && !invoice.getItems().isEmpty()) {
+            BigDecimal sumItems = invoice.getItems().stream()
+                    .map(CustomerInvoiceItem::getNetTotal)
+                    .filter(java.util.Objects::nonNull)
+                    .reduce(BigDecimal.ZERO, BigDecimal::add);
+            if (sumItems.subtract(net).abs().compareTo(AMOUNT_TOLERANCE) > 0) {
+                violations.add("Summe der Positionen (netto) " + sumItems + " weicht vom Rechnungs-Netto " + net
+                        + " ab (Differenz > 1 Cent).");
+            }
+        }
+    }
+
+    private void checkVatNotices(CustomerInvoice invoice, List<String> violations) {
+        BigDecimal rate = invoice.getVatRate();
+        if (rate == null) {
+            violations.add("Steuersatz fehlt (§ 14 Abs. 4 Nr. 8 UStG).");
+            return;
+        }
+        if (rate.signum() == 0) {
+            // Bei 0 % USt verlangt das UStG einen erklärenden Hinweis — entweder
+            // Reverse-Charge (§ 13b), Kleinunternehmerregelung (§ 19), eine
+            // innergemeinschaftliche Lieferung (§ 6a) oder eine andere Steuerbefreiung.
+            // Ohne Hinweis ist eine 0 %-Rechnung formal mangelhaft.
+            boolean hasNotice = !isBlank(invoice.getReverseChargeNote()) || !isBlank(invoice.getLegalNotes());
+            if (!hasNotice) {
+                violations.add("Bei 0 % USt ist ein rechtlicher Hinweis erforderlich "
+                        + "(z.B. \"Steuerschuldnerschaft des Leistungsempfängers\" nach § 13b UStG, "
+                        + "Kleinunternehmerregelung § 19 UStG oder Steuerbefreiung). "
+                        + "Bitte im Feld \"Reverse-Charge-Hinweis\" oder \"Rechtliche Hinweise\" ergänzen.");
+            }
+        } else {
+            BigDecimal expectedVat = invoice.getNetAmount() != null
+                    ? invoice.getNetAmount().multiply(rate).setScale(2, RoundingMode.HALF_UP)
+                    : null;
+            if (expectedVat != null && invoice.getVatAmount() != null
+                    && expectedVat.subtract(invoice.getVatAmount()).abs().compareTo(AMOUNT_TOLERANCE) > 0) {
+                violations.add("Ausgewiesener Steuerbetrag " + invoice.getVatAmount()
+                        + " passt nicht zu Netto × Steuersatz (erwartet " + expectedVat + ").");
+            }
+        }
+    }
+
+    private boolean isBlank(String value) {
+        return value == null || value.isBlank();
+    }
+}

backend/src/main/java/de/assecutor/votianlt/service/InvoiceExportService.java

@@ -0,0 +1,182 @@
+package de.assecutor.votianlt.service;
+
+import de.assecutor.votianlt.model.invoices.CustomerInvoice;
+import de.assecutor.votianlt.model.invoices.InvoiceAuditEntry;
+import de.assecutor.votianlt.model.invoices.InvoiceType;
+import de.assecutor.votianlt.repository.CustomerInvoiceRepository;
+import org.springframework.stereotype.Service;
+
+import java.io.ByteArrayOutputStream;
+import java.nio.charset.StandardCharsets;
+import java.time.format.DateTimeFormatter;
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Locale;
+import java.util.Set;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipOutputStream;
+
+/**
+ * Export-Funktion für Rechnungen gemäß R-33 und R-34.
+ *
+ * Bündelt eine Originalrechnung mit allen erzeugten Folgebelegen
+ * (Storno, Berichtigung, Ersatzrechnung) sowie einer Manifest-Datei
+ * mit Audit-Log und Verkettungsangaben in einer ZIP-Datei.
+ */
+@Service
+public class InvoiceExportService {
+
+    private static final DateTimeFormatter TS_FMT = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss",
+            Locale.GERMANY);
+
+    private final CustomerInvoiceRepository invoiceRepository;
+
+    public InvoiceExportService(CustomerInvoiceRepository invoiceRepository) {
+        this.invoiceRepository = invoiceRepository;
+    }
+
+    /**
+     * Erzeugt ein ZIP-Archiv mit dem Originalbeleg, allen verlinkten Folgebelegen
+     * sowie einer Manifest-Datei. Ist die übergebene Rechnung selbst ein Folgebeleg,
+     * wird automatisch das Bündel um die zugehörige Originalrechnung erweitert.
+     */
+    public byte[] exportInvoicePackage(CustomerInvoice anchor) {
+        if (anchor == null) {
+            throw new IllegalArgumentException("Rechnung erforderlich.");
+        }
+
+        CustomerInvoice root = resolveRoot(anchor);
+        List<CustomerInvoice> bundle = collectBundle(root);
+
+        try (ByteArrayOutputStream baos = new ByteArrayOutputStream();
+                ZipOutputStream zip = new ZipOutputStream(baos, StandardCharsets.UTF_8)) {
+
+            for (CustomerInvoice invoice : bundle) {
+                writePdfEntry(zip, invoice);
+            }
+
+            String manifest = buildManifest(root, bundle);
+            ZipEntry manifestEntry = new ZipEntry("MANIFEST.txt");
+            zip.putNextEntry(manifestEntry);
+            zip.write(manifest.getBytes(StandardCharsets.UTF_8));
+            zip.closeEntry();
+
+            zip.finish();
+            return baos.toByteArray();
+        } catch (Exception ex) {
+            throw new IllegalStateException("Export fehlgeschlagen: " + ex.getMessage(), ex);
+        }
+    }
+
+    /**
+     * Schlägt einen Dateinamen für das ZIP-Archiv auf Basis des Originalbelegs vor.
+     */
+    public String suggestFilename(CustomerInvoice anchor) {
+        CustomerInvoice root = resolveRoot(anchor);
+        String number = root.getInvoiceNumber() != null ? root.getInvoiceNumber() : root.getId();
+        return "Rechnung_" + sanitize(number) + ".zip";
+    }
+
+    private CustomerInvoice resolveRoot(CustomerInvoice anchor) {
+        if (anchor.getType() != InvoiceType.INVOICE && anchor.getOriginalInvoiceId() != null) {
+            return invoiceRepository.findById(anchor.getOriginalInvoiceId()).orElse(anchor);
+        }
+        return anchor;
+    }
+
+    private List<CustomerInvoice> collectBundle(CustomerInvoice root) {
+        List<CustomerInvoice> result = new ArrayList<>();
+        Set<String> seen = new HashSet<>();
+        result.add(root);
+        seen.add(root.getId());
+
+        for (CustomerInvoice related : invoiceRepository.findByOriginalInvoiceId(root.getId())) {
+            if (related.getId() != null && seen.add(related.getId())) {
+                result.add(related);
+            }
+        }
+        return result;
+    }
+
+    private void writePdfEntry(ZipOutputStream zip, CustomerInvoice invoice) throws java.io.IOException {
+        if (invoice.getPdfData() == null || invoice.getPdfData().length == 0) {
+            return;
+        }
+        String label = switch (invoice.getType() != null ? invoice.getType() : InvoiceType.INVOICE) {
+        case INVOICE -> "Rechnung";
+        case CANCELLATION -> "Storno";
+        case CORRECTION -> "Berichtigung";
+        };
+        String number = invoice.getInvoiceNumber() != null ? invoice.getInvoiceNumber() : invoice.getId();
+        String name = sanitize(label + "_" + number) + ".pdf";
+        ZipEntry entry = new ZipEntry(name);
+        zip.putNextEntry(entry);
+        zip.write(invoice.getPdfData());
+        zip.closeEntry();
+    }
+
+    private String buildManifest(CustomerInvoice root, List<CustomerInvoice> bundle) {
+        StringBuilder sb = new StringBuilder();
+        sb.append("Rechnungspaket\n");
+        sb.append("===============\n\n");
+        sb.append("Originalrechnung: ").append(safe(root.getInvoiceNumber()));
+        if (root.getInvoiceDate() != null) {
+            sb.append(" vom ").append(root.getInvoiceDate());
+        }
+        sb.append("\n");
+        sb.append("Status: ").append(root.getStatus()).append("\n");
+        sb.append("Zahlungsstatus: ").append(root.getPaymentStatus()).append("\n");
+        if (root.getTotalAmount() != null) {
+            sb.append("Gesamtbetrag: ").append(root.getTotalAmount()).append("\n");
+        }
+        if (root.getPaidAmount() != null) {
+            sb.append("Bezahlt: ").append(root.getPaidAmount()).append("\n");
+        }
+
+        sb.append("\nEnthaltene Belege:\n");
+        for (CustomerInvoice invoice : bundle) {
+            sb.append("- [").append(invoice.getType()).append("] ")
+                    .append(safe(invoice.getInvoiceNumber()));
+            if (invoice.getInvoiceDate() != null) {
+                sb.append(" vom ").append(invoice.getInvoiceDate());
+            }
+            sb.append(" — Status ").append(invoice.getStatus()).append("\n");
+        }
+
+        sb.append("\nÄnderungsprotokoll der Originalrechnung:\n");
+        List<InvoiceAuditEntry> log = root.getAuditLog();
+        if (log == null || log.isEmpty()) {
+            sb.append("(keine Einträge)\n");
+        } else {
+            for (InvoiceAuditEntry entry : log) {
+                sb.append("- ");
+                sb.append(entry.getTimestamp() != null ? entry.getTimestamp().format(TS_FMT) : "-");
+                sb.append(" · ").append(entry.getAction());
+                sb.append(" · ").append(safe(entry.getUserDisplayName()));
+                if (entry.getReason() != null && !entry.getReason().isBlank()) {
+                    sb.append(" — ").append(entry.getReason());
+                }
+                if (entry.getResultingInvoiceNumber() != null) {
+                    sb.append(" → ").append(entry.getResultingInvoiceNumber());
+                }
+                sb.append("\n");
+            }
+        }
+        sb.append(
+                "\nHinweis: Dieses Paket dient der gemeinsamen Aufbewahrung von Original und Folgebelegen.\n");
+        sb.append("Die rechtliche Aufbewahrungspflicht liegt beim Aussteller (R-31/R-32).\n");
+        return sb.toString();
+    }
+
+    private String safe(String value) {
+        return value != null ? value : "";
+    }
+
+    private String sanitize(String input) {
+        if (input == null) {
+            return "Beleg";
+        }
+        return input.replaceAll("[^A-Za-z0-9._-]", "_");
+    }
+}

backend/src/main/java/de/assecutor/votianlt/service/InvoiceLifecycleException.java

@@ -0,0 +1,18 @@
+package de.assecutor.votianlt.service;
+
+/**
+ * Wird geworfen, wenn ein Statusübergang oder eine Änderung an einer Rechnung
+ * gegen die Regeln aus <code>invoices_rules.md</code> verstößt (z.B. R-03, R-08, R-11, R-35).
+ *
+ * Die Nachricht ist als Anwendertext formuliert und kann direkt in der UI angezeigt werden.
+ */
+public class InvoiceLifecycleException extends RuntimeException {
+
+    public InvoiceLifecycleException(String message) {
+        super(message);
+    }
+
+    public InvoiceLifecycleException(String message, Throwable cause) {
+        super(message, cause);
+    }
+}

backend/src/main/java/de/assecutor/votianlt/service/InvoiceLifecycleService.java

@@ -0,0 +1,536 @@
+package de.assecutor.votianlt.service;
+
+import de.assecutor.votianlt.model.User;
+import de.assecutor.votianlt.model.invoices.CustomerInvoice;
+import de.assecutor.votianlt.model.invoices.InvoiceAuditAction;
+import de.assecutor.votianlt.model.invoices.InvoiceAuditEntry;
+import de.assecutor.votianlt.model.invoices.InvoiceStatus;
+import de.assecutor.votianlt.model.invoices.InvoiceType;
+import de.assecutor.votianlt.model.invoices.PaymentStatus;
+import de.assecutor.votianlt.repository.CustomerInvoiceRepository;
+import de.assecutor.votianlt.security.SecurityService;
+import org.bson.types.ObjectId;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.stereotype.Service;
+
+import java.math.BigDecimal;
+import java.time.LocalDate;
+import java.time.LocalDateTime;
+import java.util.List;
+import java.util.Optional;
+
+/**
+ * Verwaltet den Lebenszyklus einer {@link CustomerInvoice} gemäß den Regeln aus
+ * <code>invoices_rules.md</code>.
+ *
+ * Phase 1 stellt die Status- und Audit-Mechanik bereit:
+ * <ul>
+ *   <li>R-02/R-03: Entwürfe sind editier-/löschbar, finalisierte Belege nicht.</li>
+ *   <li>R-07: Finalisierung markiert eine Rechnung als verbindlich.</li>
+ *   <li>R-08/R-11: Verhindert Doppelvergabe der Rechnungsnummer und unsichtbare Änderungen.</li>
+ *   <li>R-35: Direktes Löschen finalisierter Belege wird abgelehnt.</li>
+ *   <li>R-36 bis R-39: Jede Statusänderung wird im Audit-Log protokolliert.</li>
+ * </ul>
+ *
+ * Korrektur-/Storno-Workflows folgen in Phase 2; entsprechende Hooks werden hier vorbereitet.
+ */
+@Service
+public class InvoiceLifecycleService {
+
+    private static final Logger log = LoggerFactory.getLogger(InvoiceLifecycleService.class);
+
+    private final CustomerInvoiceRepository invoiceRepository;
+    private final SecurityService securityService;
+    private final InvoiceComplianceValidator complianceValidator;
+    private final InvoiceNumberAuditService numberAuditService;
+
+    public InvoiceLifecycleService(CustomerInvoiceRepository invoiceRepository, SecurityService securityService,
+            InvoiceComplianceValidator complianceValidator,
+            InvoiceNumberAuditService numberAuditService) {
+        this.invoiceRepository = invoiceRepository;
+        this.securityService = securityService;
+        this.complianceValidator = complianceValidator;
+        this.numberAuditService = numberAuditService;
+    }
+
+    /**
+     * Persistiert einen neu erzeugten Rechnungsentwurf (Status DRAFT).
+     */
+    public CustomerInvoice createDraft(CustomerInvoice draft, String reason) {
+        if (draft == null) {
+            throw new IllegalArgumentException("Rechnungsentwurf darf nicht null sein.");
+        }
+        draft.setStatus(InvoiceStatus.DRAFT);
+        if (draft.getType() == null) {
+            draft.setType(InvoiceType.INVOICE);
+        }
+        draft.addAuditEntry(audit(InvoiceAuditAction.CREATED_DRAFT, reason));
+        return invoiceRepository.save(draft);
+    }
+
+    /**
+     * Erzeugt eine Rechnung und finalisiert sie unmittelbar (Status ISSUED).
+     * Wird vom bestehenden Erstell-Flow verwendet, der Vorschau und Speichern in
+     * einem Schritt vereint (R-06/R-07).
+     */
+    public CustomerInvoice createAndIssue(CustomerInvoice invoice, String reason) {
+        if (invoice == null) {
+            throw new IllegalArgumentException("Rechnung darf nicht null sein.");
+        }
+        if (invoice.getType() == null) {
+            invoice.setType(InvoiceType.INVOICE);
+        }
+        complianceValidator.validateForIssuance(invoice);
+        ensureInvoiceNumberUnique(invoice);
+        invoice.setStatus(InvoiceStatus.ISSUED);
+        invoice.setIssuedAt(LocalDateTime.now());
+        invoice.addAuditEntry(audit(InvoiceAuditAction.CREATED_DRAFT, reason));
+        invoice.addAuditEntry(audit(InvoiceAuditAction.ISSUED, reason));
+        CustomerInvoice saved = invoiceRepository.save(invoice);
+        numberAuditService.markUsed(saved);
+        return saved;
+    }
+
+    /**
+     * Speichert Änderungen an einem bestehenden Entwurf (R-02/R-05).
+     * Lehnt Änderungen an finalisierten Rechnungen ab (R-03/R-08).
+     */
+    public CustomerInvoice updateDraft(CustomerInvoice draft, String reason) {
+        if (draft == null || draft.getId() == null) {
+            throw new IllegalArgumentException("Bestehender Entwurf erwartet.");
+        }
+        CustomerInvoice persisted = invoiceRepository.findById(draft.getId())
+                .orElseThrow(() -> new IllegalStateException("Rechnung nicht gefunden: " + draft.getId()));
+        if (!persisted.getStatus().isMutable()) {
+            throw new InvoiceLifecycleException(
+                    "Diese Rechnung ist bereits ausgestellt und kann nicht mehr direkt bearbeitet werden. "
+                            + "Bitte erstellen Sie eine Berichtigung oder ein Storno.");
+        }
+        draft.setStatus(InvoiceStatus.DRAFT);
+        draft.setAuditLog(persisted.getAuditLog());
+        draft.addAuditEntry(audit(InvoiceAuditAction.UPDATED_DRAFT, reason));
+        return invoiceRepository.save(draft);
+    }
+
+    /**
+     * Finalisiert einen Entwurf (Status ISSUED). Stellt sicher, dass die Rechnungsnummer
+     * eindeutig ist (R-11) und protokolliert den Wechsel.
+     */
+    public CustomerInvoice issue(String invoiceId, String reason) {
+        CustomerInvoice invoice = requireInvoice(invoiceId);
+        if (invoice.getStatus() == InvoiceStatus.ISSUED || invoice.getStatus() == InvoiceStatus.SENT) {
+            return invoice;
+        }
+        if (invoice.getStatus() != InvoiceStatus.DRAFT) {
+            throw new InvoiceLifecycleException(
+                    "Nur Entwürfe können ausgestellt werden. Aktueller Status: " + invoice.getStatus());
+        }
+        complianceValidator.validateForIssuance(invoice);
+        ensureInvoiceNumberUnique(invoice);
+        invoice.setStatus(InvoiceStatus.ISSUED);
+        invoice.setIssuedAt(LocalDateTime.now());
+        invoice.addAuditEntry(audit(InvoiceAuditAction.ISSUED, reason));
+        CustomerInvoice saved = invoiceRepository.save(invoice);
+        numberAuditService.markUsed(saved);
+        return saved;
+    }
+
+    /**
+     * Markiert eine ausgestellte Rechnung als versendet (R-08).
+     */
+    public CustomerInvoice markAsSent(String invoiceId, String reason) {
+        CustomerInvoice invoice = requireInvoice(invoiceId);
+        if (invoice.getStatus() == InvoiceStatus.DRAFT) {
+            throw new InvoiceLifecycleException(
+                    "Eine Rechnung muss vor dem Versand zunächst ausgestellt werden.");
+        }
+        if (invoice.getStatus() == InvoiceStatus.CANCELLED) {
+            throw new InvoiceLifecycleException("Eine stornierte Rechnung kann nicht mehr versendet werden.");
+        }
+        invoice.setStatus(InvoiceStatus.SENT);
+        invoice.setSentAt(LocalDateTime.now());
+        invoice.addAuditEntry(audit(InvoiceAuditAction.SENT, reason));
+        return invoiceRepository.save(invoice);
+    }
+
+    /**
+     * Erzeugt einen Stornobeleg zu einer bereits ausgestellten Rechnung (R-17 bis R-22).
+     *
+     * Der Stornobeleg ist ein eigenständiger Beleg vom Typ {@link InvoiceType#CANCELLATION}
+     * mit eigener (neuer) Rechnungsnummer. Die Originalrechnung wird auf
+     * {@link InvoiceStatus#CANCELLED} gesetzt; Original und Storno sind über
+     * {@code originalInvoiceId} bzw. {@code cancellationInvoiceId} verlinkt.
+     *
+     * @param originalId        ID der zu stornierenden Rechnung
+     * @param cancellationNumber neue, fortlaufende Rechnungsnummer für den Stornobeleg
+     * @param cancellationDate   Belegdatum des Stornos
+     * @param pdfData            generiertes PDF des Stornobelegs
+     * @param reason             nachvollziehbarer Grund (R-36)
+     */
+    public CustomerInvoice cancel(String originalId, String cancellationNumber, LocalDate cancellationDate,
+            byte[] pdfData, String reason) {
+        CustomerInvoice original = requireInvoice(originalId);
+        if (original.getType() != InvoiceType.INVOICE) {
+            throw new InvoiceLifecycleException(
+                    "Nur reguläre Rechnungen können storniert werden. Belegtyp: " + original.getType());
+        }
+        if (original.getStatus() == InvoiceStatus.CANCELLED) {
+            throw new InvoiceLifecycleException("Diese Rechnung ist bereits storniert.");
+        }
+        if (original.getStatus() == InvoiceStatus.DRAFT) {
+            throw new InvoiceLifecycleException(
+                    "Ein Entwurf wird nicht storniert, sondern gelöscht oder bearbeitet.");
+        }
+        if (cancellationNumber == null || cancellationNumber.isBlank()) {
+            throw new InvoiceLifecycleException("Stornobeleg benötigt eine fortlaufende Belegnummer.");
+        }
+
+        CustomerInvoice cancellation = new CustomerInvoice();
+        cancellation.setType(InvoiceType.CANCELLATION);
+        cancellation.setStatus(InvoiceStatus.ISSUED);
+        cancellation.setInvoiceNumber(cancellationNumber);
+        cancellation.setInvoiceDate(cancellationDate != null ? cancellationDate : LocalDate.now());
+        cancellation.setIssuedAt(LocalDateTime.now());
+        cancellation.setUserId(original.getUserId());
+        cancellation.setJobId(original.getJobId());
+        cancellation.setOriginalInvoiceId(original.getId());
+        cancellation.setOriginalInvoiceNumber(original.getInvoiceNumber());
+        cancellation.setOriginalInvoiceDate(original.getInvoiceDate());
+
+        // Empfänger-/Sender-Daten übernehmen für vollständige Pflichtangaben
+        copyParties(original, cancellation);
+        cancellation.setItems(original.getItems());
+
+        // Beträge negieren – Storno bucht den Originalbetrag aus
+        cancellation.setNetAmount(negate(original.getNetAmount()));
+        cancellation.setVatRate(original.getVatRate());
+        cancellation.setVatAmount(negate(original.getVatAmount()));
+        cancellation.setTotalAmount(negate(original.getTotalAmount()));
+
+        cancellation.setDescription("Stornorechnung zu Rechnung " + original.getInvoiceNumber());
+        cancellation.setPdfData(pdfData);
+        cancellation.addAuditEntry(audit(InvoiceAuditAction.CREATED_DRAFT, reason));
+        InvoiceAuditEntry issuedEntry = audit(InvoiceAuditAction.ISSUED, reason);
+        issuedEntry.setResultingInvoiceNumber(cancellationNumber);
+        cancellation.addAuditEntry(issuedEntry);
+
+        ensureInvoiceNumberUnique(cancellation);
+        CustomerInvoice savedCancellation = invoiceRepository.save(cancellation);
+        numberAuditService.markUsed(savedCancellation);
+
+        // Original markieren und verlinken
+        original.setStatus(InvoiceStatus.CANCELLED);
+        original.setCancelledAt(LocalDateTime.now());
+        original.setCancellationInvoiceId(savedCancellation.getId());
+        // Wenn die Originalrechnung bereits (teil-)bezahlt war, entsteht ein Erstattungsanspruch (R-26)
+        BigDecimal paid = original.getPaidAmount() != null ? original.getPaidAmount() : BigDecimal.ZERO;
+        original.setPaymentStatus(computePaymentStatus(original, paid));
+        InvoiceAuditEntry cancelEntry = audit(InvoiceAuditAction.CANCELLED, reason);
+        cancelEntry.setResultingInvoiceId(savedCancellation.getId());
+        cancelEntry.setResultingInvoiceNumber(savedCancellation.getInvoiceNumber());
+        original.addAuditEntry(cancelEntry);
+        invoiceRepository.save(original);
+
+        log.info("Rechnung {} storniert durch Beleg {}.", original.getInvoiceNumber(),
+                savedCancellation.getInvoiceNumber());
+        return savedCancellation;
+    }
+
+    /**
+     * Erzeugt einen Berichtigungsbeleg zu einer bereits ausgestellten Rechnung (R-12 bis R-16).
+     *
+     * Eine Berichtigung adressiert formale Fehler (Adresse, Leistungsdatum, Pflichtangabe).
+     * Sie ersetzt die Originalrechnung nicht, sondern verweist auf sie. Originalrechnung
+     * wechselt in den Status {@link InvoiceStatus#CORRECTED} und hält eine Referenz auf den
+     * Berichtigungsbeleg.
+     *
+     * @param originalId         ID der zu berichtigenden Rechnung
+     * @param correctionNumber   fortlaufende Belegnummer für den Berichtigungsbeleg
+     * @param correctionDate     Belegdatum
+     * @param pdfData            generiertes PDF des Berichtigungsbelegs
+     * @param correctedFields    Beschreibung der ergänzten/korrigierten Angaben (R-14)
+     * @param reason             Grund der Berichtigung (R-36)
+     */
+    public CustomerInvoice correct(String originalId, String correctionNumber, LocalDate correctionDate,
+            byte[] pdfData, String correctedFields, String reason) {
+        CustomerInvoice original = requireInvoice(originalId);
+        if (original.getType() != InvoiceType.INVOICE) {
+            throw new InvoiceLifecycleException(
+                    "Nur reguläre Rechnungen können berichtigt werden. Belegtyp: " + original.getType());
+        }
+        if (original.getStatus() == InvoiceStatus.DRAFT) {
+            throw new InvoiceLifecycleException(
+                    "Ein Entwurf wird nicht berichtigt, sondern direkt bearbeitet.");
+        }
+        if (original.getStatus() == InvoiceStatus.CANCELLED) {
+            throw new InvoiceLifecycleException(
+                    "Eine bereits stornierte Rechnung kann nicht berichtigt werden. Erstellen Sie eine neue Rechnung.");
+        }
+        if (correctionNumber == null || correctionNumber.isBlank()) {
+            throw new InvoiceLifecycleException("Berichtigungsbeleg benötigt eine fortlaufende Belegnummer.");
+        }
+
+        CustomerInvoice correction = new CustomerInvoice();
+        correction.setType(InvoiceType.CORRECTION);
+        correction.setStatus(InvoiceStatus.ISSUED);
+        correction.setInvoiceNumber(correctionNumber);
+        correction.setInvoiceDate(correctionDate != null ? correctionDate : LocalDate.now());
+        correction.setIssuedAt(LocalDateTime.now());
+        correction.setUserId(original.getUserId());
+        correction.setJobId(original.getJobId());
+        correction.setOriginalInvoiceId(original.getId());
+        correction.setOriginalInvoiceNumber(original.getInvoiceNumber());
+        correction.setOriginalInvoiceDate(original.getInvoiceDate());
+
+        copyParties(original, correction);
+        correction.setItems(original.getItems());
+        correction.setNetAmount(original.getNetAmount());
+        correction.setVatRate(original.getVatRate());
+        correction.setVatAmount(original.getVatAmount());
+        correction.setTotalAmount(original.getTotalAmount());
+
+        String descriptionPrefix = "Berichtigung zu Rechnung " + original.getInvoiceNumber();
+        correction.setDescription(
+                correctedFields == null || correctedFields.isBlank() ? descriptionPrefix
+                        : descriptionPrefix + " — " + correctedFields);
+        correction.setPdfData(pdfData);
+        correction.addAuditEntry(audit(InvoiceAuditAction.CREATED_DRAFT, reason));
+        InvoiceAuditEntry issuedEntry = audit(InvoiceAuditAction.ISSUED, reason);
+        issuedEntry.setResultingInvoiceNumber(correctionNumber);
+        correction.addAuditEntry(issuedEntry);
+
+        ensureInvoiceNumberUnique(correction);
+        CustomerInvoice savedCorrection = invoiceRepository.save(correction);
+        numberAuditService.markUsed(savedCorrection);
+
+        original.setStatus(InvoiceStatus.CORRECTED);
+        original.setCorrectionInvoiceId(savedCorrection.getId());
+        InvoiceAuditEntry correctEntry = audit(InvoiceAuditAction.CORRECTED, reason);
+        correctEntry.setResultingInvoiceId(savedCorrection.getId());
+        correctEntry.setResultingInvoiceNumber(savedCorrection.getInvoiceNumber());
+        original.addAuditEntry(correctEntry);
+        invoiceRepository.save(original);
+
+        log.info("Rechnung {} berichtigt durch Beleg {}.", original.getInvoiceNumber(),
+                savedCorrection.getInvoiceNumber());
+        return savedCorrection;
+    }
+
+    /**
+     * Speichert eine vollständig neue Ersatzrechnung nach einem Storno (R-20 bis R-22).
+     * Die neue Rechnung erhält eine eigene Rechnungsnummer und referenziert die stornierte
+     * Originalrechnung, sodass die Verkettung Original → Storno → Ersatzrechnung erhalten bleibt.
+     */
+    public CustomerInvoice createReplacementInvoice(String cancelledOriginalId, CustomerInvoice replacement,
+            String reason) {
+        CustomerInvoice cancelledOriginal = requireInvoice(cancelledOriginalId);
+        if (cancelledOriginal.getStatus() != InvoiceStatus.CANCELLED) {
+            throw new InvoiceLifecycleException(
+                    "Eine Ersatzrechnung kann nur zu einer stornierten Rechnung erstellt werden.");
+        }
+        if (replacement == null) {
+            throw new IllegalArgumentException("Ersatzrechnung darf nicht null sein.");
+        }
+        replacement.setType(InvoiceType.INVOICE);
+        replacement.setOriginalInvoiceId(cancelledOriginal.getId());
+        replacement.setOriginalInvoiceNumber(cancelledOriginal.getInvoiceNumber());
+        replacement.setOriginalInvoiceDate(cancelledOriginal.getInvoiceDate());
+
+        CustomerInvoice savedReplacement = createAndIssue(replacement,
+                reason != null ? reason : "Ersatzrechnung nach Storno");
+
+        cancelledOriginal.setReplacementInvoiceId(savedReplacement.getId());
+        InvoiceAuditEntry replaceEntry = audit(InvoiceAuditAction.REPLACED, reason);
+        replaceEntry.setResultingInvoiceId(savedReplacement.getId());
+        replaceEntry.setResultingInvoiceNumber(savedReplacement.getInvoiceNumber());
+        cancelledOriginal.addAuditEntry(replaceEntry);
+        invoiceRepository.save(cancelledOriginal);
+
+        return savedReplacement;
+    }
+
+    /**
+     * Liefert die Folgebelege (Storno, Berichtigung, Ersatzrechnung) zu einer Rechnung.
+     */
+    public List<CustomerInvoice> findRelatedDocuments(String originalInvoiceId) {
+        if (originalInvoiceId == null) {
+            return List.of();
+        }
+        return invoiceRepository.findByOriginalInvoiceId(originalInvoiceId);
+    }
+
+    /**
+     * Erfasst eine Zahlung zur Rechnung (R-23 bis R-26).
+     *
+     * Eine Zahlung wird ausschließlich erfasst – die Rechnungsdaten selbst werden nicht
+     * verändert (R-25). Der Zahlungsstatus ergibt sich aus dem Verhältnis Zahlung zu
+     * Bruttobetrag der Rechnung.
+     *
+     * @param invoiceId       Rechnung, auf die gebucht wird
+     * @param amount          erfasster Zahlbetrag (kann negativ sein für Korrekturen)
+     * @param paymentReference frei wählbarer Referenztext (z.B. Kontoauszug, Beleg)
+     * @param reason           erläuternder Grund für das Audit-Log
+     */
+    public CustomerInvoice registerPayment(String invoiceId, BigDecimal amount, String paymentReference,
+            String reason) {
+        if (amount == null) {
+            throw new IllegalArgumentException("Zahlbetrag erforderlich.");
+        }
+        CustomerInvoice invoice = requireInvoice(invoiceId);
+        if (invoice.getStatus() == InvoiceStatus.DRAFT) {
+            throw new InvoiceLifecycleException(
+                    "Auf Entwürfen können keine Zahlungen erfasst werden. Bitte zuerst ausstellen.");
+        }
+        if (invoice.getType() == InvoiceType.CORRECTION) {
+            throw new InvoiceLifecycleException(
+                    "Auf Berichtigungsbelegen werden keine Zahlungen erfasst – buchen Sie auf der Originalrechnung.");
+        }
+
+        BigDecimal previous = invoice.getPaidAmount() != null ? invoice.getPaidAmount() : BigDecimal.ZERO;
+        BigDecimal newPaid = previous.add(amount);
+        invoice.setPaidAmount(newPaid);
+        invoice.setLastPaymentAt(LocalDateTime.now());
+        invoice.setPaymentStatus(computePaymentStatus(invoice, newPaid));
+
+        StringBuilder logReason = new StringBuilder();
+        logReason.append("Zahlung erfasst: ").append(amount.toPlainString());
+        if (paymentReference != null && !paymentReference.isBlank()) {
+            logReason.append(" (Referenz: ").append(paymentReference).append(")");
+        }
+        if (reason != null && !reason.isBlank()) {
+            logReason.append(" – ").append(reason);
+        }
+        invoice.addAuditEntry(audit(InvoiceAuditAction.PAYMENT_RECORDED, logReason.toString()));
+
+        return invoiceRepository.save(invoice);
+    }
+
+    /**
+     * Liefert den noch offenen Betrag einer Rechnung. Negative Werte zeigen eine
+     * Überzahlung bzw. einen Erstattungsanspruch (R-26).
+     */
+    public BigDecimal computeOutstandingAmount(CustomerInvoice invoice) {
+        BigDecimal total = invoice.getTotalAmount() != null ? invoice.getTotalAmount() : BigDecimal.ZERO;
+        BigDecimal paid = invoice.getPaidAmount() != null ? invoice.getPaidAmount() : BigDecimal.ZERO;
+        return total.subtract(paid);
+    }
+
+    private PaymentStatus computePaymentStatus(CustomerInvoice invoice, BigDecimal paid) {
+        BigDecimal total = invoice.getTotalAmount() != null ? invoice.getTotalAmount() : BigDecimal.ZERO;
+        if (invoice.getStatus() == InvoiceStatus.CANCELLED) {
+            return paid.signum() == 0 ? PaymentStatus.UNPAID : PaymentStatus.REFUND_DUE;
+        }
+        int cmp = paid.compareTo(total);
+        if (paid.signum() == 0) {
+            return PaymentStatus.UNPAID;
+        }
+        if (cmp == 0) {
+            return PaymentStatus.PAID;
+        }
+        if (cmp < 0) {
+            return PaymentStatus.PARTIALLY_PAID;
+        }
+        return PaymentStatus.OVERPAID;
+    }
+
+    /**
+     * Löscht einen Entwurf. Finalisierte Rechnungen dürfen nicht gelöscht werden (R-35).
+     */
+    public void deleteDraft(String invoiceId, String reason) {
+        CustomerInvoice invoice = requireInvoice(invoiceId);
+        if (!invoice.getStatus().isMutable()) {
+            throw new InvoiceLifecycleException(
+                    "Finalisierte Rechnungen können nicht gelöscht werden. "
+                            + "Bitte führen Sie stattdessen ein Storno oder eine Berichtigung durch.");
+        }
+        invoice.addAuditEntry(audit(InvoiceAuditAction.DELETED_DRAFT, reason));
+        log.info("Rechnungsentwurf {} wird gelöscht: {}", invoiceId, reason);
+        invoiceRepository.delete(invoice);
+        // Wenn dem Entwurf bereits eine Nummer reserviert wurde, dokumentiert das
+        // Verwerfen jetzt die Lücke im Nummernkreis — sonst bliebe die Reservierung
+        // als unerklärter „RESERVED"-Eintrag im Audit hängen.
+        if (invoice.getInvoiceNumber() != null && !invoice.getInvoiceNumber().isBlank()
+                && invoice.getUserId() != null) {
+            try {
+                ObjectId userId = new ObjectId(invoice.getUserId());
+                String voidReason = (reason != null && !reason.isBlank())
+                        ? reason
+                        : "Rechnungsentwurf gelöscht";
+                numberAuditService.markVoided(userId, invoice.getInvoiceNumber(), voidReason);
+            } catch (IllegalArgumentException | InvoiceLifecycleException ex) {
+                // Keine Reservierung vorhanden oder UserId nicht parsebar — Lücken-Detektor
+                // erfasst das später; das Löschen selbst soll nicht blockiert werden.
+                log.debug("VOIDED-Markierung beim Löschen des Entwurfs übersprungen: {}", ex.getMessage());
+            }
+        }
+    }
+
+    public Optional<CustomerInvoice> findById(String invoiceId) {
+        return invoiceRepository.findById(invoiceId);
+    }
+
+    private CustomerInvoice requireInvoice(String invoiceId) {
+        if (invoiceId == null || invoiceId.isBlank()) {
+            throw new IllegalArgumentException("Rechnungs-ID erforderlich.");
+        }
+        return invoiceRepository.findById(invoiceId)
+                .orElseThrow(() -> new IllegalStateException("Rechnung nicht gefunden: " + invoiceId));
+    }
+
+    private void ensureInvoiceNumberUnique(CustomerInvoice invoice) {
+        String number = invoice.getInvoiceNumber();
+        if (number == null || number.isBlank()) {
+            throw new InvoiceLifecycleException("Eine ausgestellte Rechnung benötigt eine Rechnungsnummer.");
+        }
+        invoiceRepository.findByInvoiceNumberAndStatusNot(number, InvoiceStatus.CANCELLED).ifPresent(existing -> {
+            if (!existing.getId().equals(invoice.getId())) {
+                throw new InvoiceLifecycleException(
+                        "Rechnungsnummer " + number + " wird bereits von einer aktiven Rechnung verwendet.");
+            }
+        });
+    }
+
+    private InvoiceAuditEntry audit(InvoiceAuditAction action, String reason) {
+        String userId = null;
+        String displayName = "system";
+        try {
+            User user = securityService.getCurrentDatabaseUser();
+            userId = user.getId() != null ? user.getId().toHexString() : null;
+            String composed = (safe(user.getFirstname()) + " " + safe(user.getName())).trim();
+            displayName = composed.isBlank() ? safe(user.getEmail()) : composed;
+        } catch (Exception ignored) {
+            // Audit funktioniert auch außerhalb einer Vaadin-Session (z.B. Migration).
+        }
+        return new InvoiceAuditEntry(action, userId, displayName, reason);
+    }
+
+    private String safe(String value) {
+        return value != null ? value : "";
+    }
+
+    private void copyParties(CustomerInvoice source, CustomerInvoice target) {
+        target.setSenderName(source.getSenderName());
+        target.setSenderAddress(source.getSenderAddress());
+        target.setSenderPostcode(source.getSenderPostcode());
+        target.setSenderCity(source.getSenderCity());
+        target.setSenderCountry(source.getSenderCountry());
+        target.setSenderTaxNumber(source.getSenderTaxNumber());
+        target.setSenderVatId(source.getSenderVatId());
+        target.setSenderPhone(source.getSenderPhone());
+        target.setSenderEmail(source.getSenderEmail());
+        target.setSenderWebsite(source.getSenderWebsite());
+
+        target.setRecipientName(source.getRecipientName());
+        target.setRecipientCompany(source.getRecipientCompany());
+        target.setRecipientAddress(source.getRecipientAddress());
+        target.setRecipientPostcode(source.getRecipientPostcode());
+        target.setRecipientCity(source.getRecipientCity());
+        target.setRecipientCountry(source.getRecipientCountry());
+        target.setRecipientVatId(source.getRecipientVatId());
+    }
+
+    private BigDecimal negate(BigDecimal value) {
+        return value != null ? value.negate() : null;
+    }
+}

backend/src/main/java/de/assecutor/votianlt/service/InvoiceNumberAuditService.java

@@ -0,0 +1,166 @@
+package de.assecutor.votianlt.service;
+
+import de.assecutor.votianlt.model.invoices.CustomerInvoice;
+import de.assecutor.votianlt.model.invoices.InvoiceNumberReservation;
+import de.assecutor.votianlt.model.invoices.InvoiceNumberReservationStatus;
+import de.assecutor.votianlt.repository.InvoiceNumberReservationRepository;
+import org.bson.types.ObjectId;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.stereotype.Service;
+
+import java.time.Instant;
+import java.util.List;
+import java.util.Optional;
+
+/**
+ * Verwaltet das Audit der vergebenen Rechnungsnummern. Jede Vergabe aus dem
+ * Counter wird als RESERVED protokolliert; dieser Service vollzieht die
+ * Status-Übergänge nach (USED beim Festschreiben, VOIDED beim Verwerfen)
+ * und liefert Lücken-Reports für die Betriebsprüfung.
+ *
+ * Pflichtgrundlage: § 14 Abs. 4 Nr. 4 UStG verlangt eine fortlaufende
+ * Rechnungsnummer; lückenhafte Nummernkreise sind nur zulässig, wenn jede
+ * fehlende Nummer dokumentiert erklärt werden kann (GoBD).
+ *
+ * Fehler beim Audit-Schreiben werden bewusst nicht propagiert: Die
+ * fachliche Operation (Rechnung festschreiben) hat Vorrang. Verlorene
+ * USED-Markierungen sind über den Lücken-Report nachträglich rekonstruierbar.
+ */
+@Service
+public class InvoiceNumberAuditService {
+
+    private static final Logger log = LoggerFactory.getLogger(InvoiceNumberAuditService.class);
+
+    private final InvoiceNumberReservationRepository repository;
+
+    public InvoiceNumberAuditService(InvoiceNumberReservationRepository repository) {
+        this.repository = repository;
+    }
+
+    /**
+     * Markiert die Reservierung der übergebenen Rechnung als USED.
+     * Wird vom Lifecycle nach erfolgreichem Festschreiben aufgerufen.
+     */
+    public void markUsed(CustomerInvoice invoice) {
+        if (invoice == null || invoice.getInvoiceNumber() == null || invoice.getUserId() == null) {
+            return;
+        }
+        ObjectId userId = parseUserId(invoice.getUserId());
+        if (userId == null) {
+            return;
+        }
+        try {
+            Optional<InvoiceNumberReservation> existing = repository.findByUserIdAndNumber(userId,
+                    invoice.getInvoiceNumber());
+            InvoiceNumberReservation reservation = existing.orElseGet(() -> bootstrapReservation(userId, invoice));
+            reservation.setStatus(InvoiceNumberReservationStatus.USED);
+            reservation.setInvoiceId(invoice.getId());
+            reservation.setUsedAt(Instant.now());
+            repository.save(reservation);
+        } catch (Exception ex) {
+            log.warn("USED-Markierung für Nummer {} (Rechnung {}) fehlgeschlagen: {}",
+                    invoice.getInvoiceNumber(), invoice.getId(), ex.getMessage(), ex);
+        }
+    }
+
+    /**
+     * Markiert die zur übergebenen Nummer gehörende Reservierung als VOIDED.
+     * Pflichtfeld {@code reason} dokumentiert die Erklärung der Lücke.
+     */
+    public void markVoided(ObjectId userId, String number, String reason) {
+        if (userId == null || number == null || number.isBlank()) {
+            throw new IllegalArgumentException("userId und number sind Pflichtparameter.");
+        }
+        if (reason == null || reason.isBlank()) {
+            throw new IllegalArgumentException("Grund (reason) ist Pflicht beim Verwerfen einer Reservierung.");
+        }
+        InvoiceNumberReservation reservation = repository.findByUserIdAndNumber(userId, number)
+                .orElseThrow(() -> new InvoiceLifecycleException(
+                        "Keine Reservierung für Nummer " + number + " gefunden."));
+        if (reservation.getStatus() == InvoiceNumberReservationStatus.USED) {
+            throw new InvoiceLifecycleException(
+                    "Nummer " + number + " ist bereits einer ausgestellten Rechnung zugeordnet "
+                            + "und kann nicht verworfen werden.");
+        }
+        reservation.setStatus(InvoiceNumberReservationStatus.VOIDED);
+        reservation.setVoidReason(reason);
+        reservation.setVoidedAt(Instant.now());
+        repository.save(reservation);
+    }
+
+    /**
+     * Liefert alle Reservierungen eines Nutzers in Sequenzreihenfolge.
+     * Basis für vollständige Audit-Reports.
+     */
+    public List<InvoiceNumberReservation> findAll(ObjectId userId) {
+        return repository.findByUserIdOrderBySequenceAsc(userId);
+    }
+
+    /**
+     * Liefert nur die noch nicht verwendeten Reservierungen eines Nutzers
+     * (Status RESERVED oder VOIDED). Im Idealfall ist diese Liste leer oder
+     * enthält ausschließlich VOIDED-Einträge mit dokumentiertem Grund.
+     * Verbleibende RESERVED-Einträge nach abgeschlossenen Vorgängen sind
+     * unerklärte Lücken und sollten in der UI hervorgehoben werden.
+     */
+    public List<InvoiceNumberReservation> findUnused(ObjectId userId) {
+        List<InvoiceNumberReservation> all = repository.findByUserIdOrderBySequenceAsc(userId);
+        return all.stream()
+                .filter(r -> r.getStatus() != InvoiceNumberReservationStatus.USED)
+                .toList();
+    }
+
+    /**
+     * Erzeugt einen Bootstrap-Eintrag für Rechnungen, die ohne vorausgegangene
+     * Reservierung festgeschrieben wurden — z.B. Bestandsdaten aus der Zeit
+     * vor Einführung des Reservierungs-Audits oder Storno-/Korrekturbelege,
+     * deren Nummer extern übergeben wurde. Status wird direkt auf USED gesetzt.
+     */
+    private InvoiceNumberReservation bootstrapReservation(ObjectId userId, CustomerInvoice invoice) {
+        InvoiceNumberReservation reservation = new InvoiceNumberReservation();
+        reservation.setUserId(userId);
+        reservation.setNumber(invoice.getInvoiceNumber());
+        reservation.setSequence(extractSequence(invoice.getInvoiceNumber()));
+        reservation.setReservedAt(Instant.now());
+        reservation.setReservedBy("system (bootstrap)");
+        return reservation;
+    }
+
+    /**
+     * Best-effort-Extraktion der numerischen Sequenz aus einer formatierten
+     * Rechnungsnummer (z.B. „RE-2026-000123" → 123). Liefert -1, wenn keine
+     * trailing-Ziffern vorhanden sind — dann ist die Nummer für die
+     * Lücken-Sortierung ungeeignet, aber der Audit-Eintrag bleibt erhalten.
+     */
+    private long extractSequence(String number) {
+        if (number == null) {
+            return -1L;
+        }
+        int end = number.length();
+        int start = end;
+        while (start > 0 && Character.isDigit(number.charAt(start - 1))) {
+            start--;
+        }
+        if (start == end) {
+            return -1L;
+        }
+        try {
+            return Long.parseLong(number.substring(start, end));
+        } catch (NumberFormatException ex) {
+            return -1L;
+        }
+    }
+
+    private ObjectId parseUserId(String value) {
+        if (value == null || value.isBlank()) {
+            return null;
+        }
+        try {
+            return new ObjectId(value);
+        } catch (IllegalArgumentException ex) {
+            log.warn("UserId '{}' ist keine gültige ObjectId — Audit übersprungen.", value);
+            return null;
+        }
+    }
+}

backend/src/main/java/de/assecutor/votianlt/service/InvoicePermissionService.java

@@ -0,0 +1,140 @@
+package de.assecutor.votianlt.service;
+
+import de.assecutor.votianlt.model.User;
+import de.assecutor.votianlt.model.invoices.CustomerInvoice;
+import de.assecutor.votianlt.security.InvoiceRoles;
+import de.assecutor.votianlt.security.SecurityService;
+import org.springframework.stereotype.Service;
+
+import java.util.Set;
+
+/**
+ * Berechtigungs-Checks für Rechnungsaktionen gemäß R-40 bis R-42.
+ *
+ * Backwards-compat: ein Nutzer mit der bestehenden {@code USER}- oder {@code ADMIN}-Rolle,
+ * der keine der spezialisierten Invoice-Rollen besitzt, hat weiterhin volle Berechtigung
+ * — andernfalls würden alle bestehenden Installationen sofort handlungsunfähig.
+ *
+ * Sobald ein Nutzer mindestens eine {@code INVOICE_*}-Rolle hat, gelten die feingranularen
+ * Regeln und nur die explizit zugewiesenen Aktionen sind erlaubt.
+ */
+@Service
+public class InvoicePermissionService {
+
+    private static final String ROLE_ADMIN = "ADMIN";
+
+    private final SecurityService securityService;
+
+    public InvoicePermissionService(SecurityService securityService) {
+        this.securityService = securityService;
+    }
+
+    public boolean canCreateOrIssue(User user) {
+        return hasAnyInvoiceRole(user, InvoiceRoles.CREATOR) || isUnscoped(user);
+    }
+
+    public boolean canMarkAsSent(User user) {
+        return hasAnyInvoiceRole(user, InvoiceRoles.CREATOR, InvoiceRoles.REVIEWER, InvoiceRoles.APPROVER)
+                || isUnscoped(user);
+    }
+
+    public boolean canCancel(User user) {
+        return hasAnyInvoiceRole(user, InvoiceRoles.APPROVER) || isUnscoped(user);
+    }
+
+    public boolean canCorrect(User user) {
+        return hasAnyInvoiceRole(user, InvoiceRoles.APPROVER, InvoiceRoles.REVIEWER) || isUnscoped(user);
+    }
+
+    public boolean canRecordPayment(User user) {
+        return hasAnyInvoiceRole(user, InvoiceRoles.ACCOUNTANT, InvoiceRoles.APPROVER) || isUnscoped(user);
+    }
+
+    public void requireCreate(User user) {
+        if (!canCreateOrIssue(user)) {
+            throw new InvoiceLifecycleException(
+                    "Sie haben keine Berechtigung, Rechnungen zu erstellen oder auszustellen.");
+        }
+    }
+
+    public void requireSend(User user) {
+        if (!canMarkAsSent(user)) {
+            throw new InvoiceLifecycleException(
+                    "Sie haben keine Berechtigung, Rechnungen als versendet zu markieren.");
+        }
+    }
+
+    public void requireCancel(User user) {
+        if (!canCancel(user)) {
+            throw new InvoiceLifecycleException(
+                    "Sie haben keine Berechtigung, Rechnungen zu stornieren.");
+        }
+    }
+
+    public void requireCorrect(User user) {
+        if (!canCorrect(user)) {
+            throw new InvoiceLifecycleException(
+                    "Sie haben keine Berechtigung, Berichtigungsbelege zu erstellen.");
+        }
+    }
+
+    public void requirePayment(User user) {
+        if (!canRecordPayment(user)) {
+            throw new InvoiceLifecycleException("Sie haben keine Berechtigung, Zahlungen zu erfassen.");
+        }
+    }
+
+    /**
+     * Convenience: prüft, ob der Nutzer Eigentümer einer Rechnung ist (oder Admin).
+     * Wird genutzt, um Cross-Tenant-Zugriffe zu verhindern.
+     */
+    public boolean isOwnerOrAdmin(User user, CustomerInvoice invoice) {
+        if (user == null) {
+            return false;
+        }
+        if (isAdmin(user)) {
+            return true;
+        }
+        if (invoice == null || invoice.getUserId() == null || user.getId() == null) {
+            return false;
+        }
+        return invoice.getUserId().equals(user.getId().toHexString());
+    }
+
+    private boolean hasAnyInvoiceRole(User user, String... roles) {
+        if (user == null || user.getRoles() == null) {
+            return false;
+        }
+        Set<String> userRoles = user.getRoles();
+        if (userRoles.contains(ROLE_ADMIN)) {
+            return true;
+        }
+        for (String role : roles) {
+            if (userRoles.contains(role)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    /**
+     * {@code true}, wenn dem Nutzer keine spezialisierte Invoice-Rolle zugewiesen ist —
+     * dann gilt das alte Pauschalrecht der USER-Rolle (Backwards-Compat).
+     */
+    private boolean isUnscoped(User user) {
+        if (user == null || user.getRoles() == null) {
+            return false;
+        }
+        Set<String> roles = user.getRoles();
+        return roles.stream().noneMatch(r -> r.startsWith("INVOICE_"));
+    }
+
+    private boolean isAdmin(User user) {
+        return user != null && user.getRoles() != null && user.getRoles().contains(ROLE_ADMIN);
+    }
+
+    /** Bequemer Lookup für die UI. */
+    public User currentUser() {
+        return securityService.getCurrentDatabaseUser();
+    }
+}

backend/src/main/resources/messages_de.properties

@@ -242,7 +242,7 @@ page.title.appuser.create=Neuen App-Nutzer anlegen
 page.title.messages=Nachrichten
 page.title.register=Bei VotianLT registrieren
 page.title.customers=Kunden
-page.title.customer.edit=Kunde bearbeiten
+page.title.customer.edit=Adresse bearbeiten
 page.title.verwaltung=Verwaltung
 page.title.company.create=Neue Firma anlegen
 page.title.imprint=Impressum
@@ -339,13 +339,13 @@ customers.column.street=Straße
 customers.column.city=Ort
 
 # Edit Customer
-editcustomer.title=Kunde bearbeiten
-editcustomer.notification.notfound=Kunde nicht gefunden
-editcustomer.notification.invalid.id=Ungültige Kunden-ID
-editcustomer.notification.saved=Kunde erfolgreich gespeichert
+editcustomer.title=Adresse bearbeiten
+editcustomer.notification.notfound=Adresse nicht gefunden
+editcustomer.notification.invalid.id=Ungültige Adress-ID
+editcustomer.notification.saved=Adresse erfolgreich gespeichert
 editcustomer.notification.check=Bitte überprüfen Sie Ihre Eingaben
-editcustomer.notification.deleted=Kunde erfolgreich gelöscht
-editcustomer.dialog.delete.text=Möchten Sie diesen Kunden wirklich löschen?
+editcustomer.notification.deleted=Adresse erfolgreich gelöscht
+editcustomer.dialog.delete.text=Möchten Sie diese Adresse wirklich löschen?
 editcustomer.dialog.delete.confirm=Löschen
 
 # Add Customer
@@ -429,9 +429,9 @@ messages.sender.unknown=Unbekannter Absender
 
 # Add Job
 addjob.title=Neuen Auftrag anlegen
-addjob.customer.label=Kunde
-addjob.customer.placeholder=Kunde auswählen
-addjob.customer.unnamed=Unbenannter Kunde
+addjob.customer.label=Auftraggeber
+addjob.customer.placeholder=Auftraggeber auswählen
+addjob.customer.unnamed=Unbenannter Auftraggeber
 addjob.button.clearfields=Felder leeren
 addjob.button.submit=Auftrag anlegen
 addjob.address.salutation=Anrede
@@ -440,6 +440,10 @@ addjob.salutation.mr=Herr
 addjob.salutation.ms=Frau
 addjob.salutation.other=Divers
 addjob.address.company.placeholder=Firma eingeben
+addjob.address.pickup.label=Abholadresse
+addjob.address.pickup.placeholder=Abholadresse auswählen oder eingeben
+addjob.address.delivery.label=Lieferadresse
+addjob.address.delivery.placeholder=Lieferadresse auswählen oder eingeben
 addjob.address.street.placeholder=Straße eingeben
 addjob.address.housenumber=Hausnummer
 addjob.address.addition.placeholder=Adresszusatz
@@ -460,6 +464,8 @@ addjob.station.max.reached=Maximale Anzahl von 25 Lieferstationen erreicht
 addjob.station.unused=Nicht genutzt
 addjob.appointment.delivery.info=Liefertermine werden direkt in den Lieferstationen festgelegt.
 addjob.tab.addresses=Auftraggeber & Adressen
+addjob.tab.pickup.address=Auftraggeber & Abholadresse
+addjob.tab.delivery.address=Lieferadresse
 addjob.tab.appointments=Termine & Verarbeitung
 addjob.tab.cargo=Fracht
 addjob.tab.tasks=Aufgaben
@@ -621,6 +627,9 @@ jobsummary.dialog.manualcomplete.reason.required=Bitte geben Sie eine Begründun
 jobsummary.dialog.manualcomplete.cancel=Abbrechen
 jobsummary.dialog.manualcomplete.confirm=Akzeptiert
 jobsummary.history.manualcomplete.reason=Manuell beendet
+jobmanualcomplete.route.hours=Stunden
+jobmanualcomplete.route.minutes=Minuten
+jobmanualcomplete.route.manual.hint=Keine Routendaten vorhanden – bitte Entfernung und Dauer manuell erfassen.
 
 # Jobs
 jobs.title=Aufträge
@@ -697,6 +706,72 @@ invoices.column.amount=Betrag
 invoices.column.description=Beschreibung
 invoices.empty=Es wurden noch keine Rechnungen erstellt.
 invoices.notification.pdf.missing=Für diese Rechnung ist kein PDF gespeichert.
+invoices.notification.pdf.error=Die PDF-Anzeige ist fehlgeschlagen: {0}
+invoices.column.status=Status
+invoices.column.type=Typ
+invoices.column.actions=Aktionen
+invoices.disclaimer=Hinweis: Die rechtliche Aufbewahrungspflicht liegt beim Aussteller. Eine bereits ausgestellte Rechnung wird nicht überschrieben — Korrekturen erfolgen über Berichtigung oder Stornorechnung mit eindeutigem Bezug.
+invoices.status.draft=Entwurf
+invoices.status.issued=Ausgestellt
+invoices.status.sent=Versendet
+invoices.status.cancelled=Storniert
+invoices.status.corrected=Berichtigt
+invoices.type.invoice=Rechnung
+invoices.type.cancellation=Stornorechnung
+invoices.type.correction=Berichtigung
+invoices.action.view=PDF anzeigen
+invoices.action.history=Historie
+invoices.action.marksent=Versendet markieren
+invoices.action.correct=Berichtigen
+invoices.action.cancel=Stornieren
+invoices.notification.sent=Rechnung als versendet markiert.
+invoices.notification.cancelled=Stornobeleg {0} erstellt.
+invoices.notification.corrected=Berichtigungsbeleg {0} erstellt.
+invoices.notification.error=Aktion fehlgeschlagen: {0}
+invoices.cancel.title=Rechnung {0} stornieren
+invoices.cancel.hint=Die Originalrechnung bleibt unverändert sichtbar. Es wird ein eigenständiger Stornobeleg mit eigener Belegnummer erstellt, der die Originalrechnung eindeutig referenziert.
+invoices.cancel.reason=Grund der Stornierung
+invoices.cancel.reason.required=Bitte einen Grund angeben.
+invoices.cancel.confirm=Stornobeleg erstellen
+invoices.correct.title=Rechnung {0} berichtigen
+invoices.correct.hint=Eine Berichtigung dient ausschließlich der Korrektur formaler Fehler (z.B. Adresse, Leistungsdatum). Die Originalrechnung bleibt sichtbar; der Berichtigungsbeleg verweist eindeutig auf sie.
+invoices.correct.fields=Berichtigte Angaben
+invoices.correct.fields.helper=Beschreiben Sie, welche Angaben ergänzt oder ersetzt werden.
+invoices.correct.fields.required=Bitte die berichtigten Angaben beschreiben.
+invoices.correct.reason=Grund der Berichtigung
+invoices.correct.confirm=Berichtigung erstellen
+invoices.history.title=Historie zu Rechnung {0}
+invoices.history.log=Änderungsprotokoll
+invoices.history.empty=Keine Einträge vorhanden.
+invoices.history.original=Original­rechnung
+invoices.history.cancellation=Stornobeleg
+invoices.history.correction=Berichtigungsbeleg
+invoices.history.replacement=Ersatzrechnung
+invoices.audit.action.created_draft=Entwurf erstellt
+invoices.audit.action.updated_draft=Entwurf geändert
+invoices.audit.action.issued=Ausgestellt
+invoices.audit.action.sent=Versendet
+invoices.audit.action.cancelled=Storniert
+invoices.audit.action.corrected=Berichtigt
+invoices.audit.action.replaced=Ersetzt durch neue Rechnung
+invoices.audit.action.deleted_draft=Entwurf gelöscht
+invoices.audit.action.payment_recorded=Zahlung erfasst
+invoices.audit.resulting=Erzeugter Folgebeleg: {0}
+invoices.payment.unpaid=Offen
+invoices.payment.partially_paid=Teilzahlung
+invoices.payment.paid=Bezahlt
+invoices.payment.overpaid=Überzahlung
+invoices.payment.refund_due=Erstattung offen
+invoices.action.payment=Zahlung erfassen
+invoices.action.export=Exportieren
+invoices.payment.title=Zahlung zu Rechnung {0}
+invoices.payment.hint=Offener Restbetrag: {0}. Negative Beträge können zur Korrektur erfasst werden.
+invoices.payment.amount=Zahlbetrag
+invoices.payment.amount.required=Bitte einen Betrag (ungleich 0) angeben.
+invoices.payment.reference=Zahlungsreferenz (z.B. Kontoauszug, Buchungs-Nr.)
+invoices.payment.reason=Anmerkung
+invoices.payment.confirm=Zahlung erfassen
+invoices.notification.payment=Zahlung erfasst.
 
 # My Invoices
 myinvoices.title=Rechnungen

backend/src/main/resources/messages_ee.properties

@@ -377,9 +377,9 @@ messages.preview.image=Pilt
 messages.preview.empty=Eelvaade puudub
 messages.sender.unknown=Tundmatu saatja
 addjob.title=Uue tellimuse loomine
-addjob.customer.label=Klient
-addjob.customer.placeholder=Valige klient
-addjob.customer.unnamed=Nimetu klient
+addjob.customer.label=Tellija
+addjob.customer.placeholder=Vali tellija
+addjob.customer.unnamed=Nimetu tellija
 addjob.button.clearfields=T\u00fchjenda v\u00e4ljad
 addjob.button.submit=Loo tellimus
 addjob.address.salutation=P\u00f6\u00f6rdumine
@@ -388,6 +388,10 @@ addjob.salutation.mr=Hr
 addjob.salutation.ms=Pr
 addjob.salutation.other=Muu
 addjob.address.company.placeholder=Sisestage ettev\u00f5te
+addjob.address.pickup.label=Pealekorje aadress
+addjob.address.pickup.placeholder=Vali v\u00f5i sisesta pealekorje aadress
+addjob.address.delivery.label=Kohaletoimetamise aadress
+addjob.address.delivery.placeholder=Vali v\u00f5i sisesta kohaletoimetamise aadress
 addjob.address.street.placeholder=Sisestage t\u00e4nav
 addjob.address.housenumber=Majanumber
 addjob.address.addition.placeholder=Aadressi t\u00e4iend
@@ -408,6 +412,8 @@ addjob.station.max.reached=Maksimaalne arv 25 kohaletoimetamise jaama on saavuta
 addjob.station.unused=Kasutamata
 addjob.appointment.delivery.info=Kohaletoimetamise ajad m\u00e4\u00e4ratakse otse kohaletoimetamise jaamades.
 addjob.tab.addresses=Tellija ja aadressid
+addjob.tab.pickup.address=Tellija ja pealekorje aadress
+addjob.tab.delivery.address=Kohaletoimetamise aadress
 addjob.tab.appointments=Ajad ja t\u00f6\u00f6tlemine
 addjob.tab.cargo=Veosed
 addjob.tab.tasks=\u00dclesanded
@@ -567,6 +573,9 @@ jobsummary.dialog.manualcomplete.reason.required=Palun sisestage põhjendus
 jobsummary.dialog.manualcomplete.cancel=Tühista
 jobsummary.dialog.manualcomplete.confirm=Nõustu
 jobsummary.history.manualcomplete.reason=Käsitsi lõpetatud
+jobmanualcomplete.route.hours=Tunnid
+jobmanualcomplete.route.minutes=Minutid
+jobmanualcomplete.route.manual.hint=Marsruudiandmed puuduvad – palun sisestage vahemaa ja kestus käsitsi.
 jobs.title=Tellimused
 jobs.filter.search=Otsi
 jobs.filter.search.placeholder=Otsi tellimuse numbri j\u00e4rgi...

backend/src/main/resources/messages_en.properties

@@ -429,9 +429,9 @@ messages.sender.unknown=Unknown Sender
 
 # Add Job
 addjob.title=Create New Job
-addjob.customer.label=Customer
-addjob.customer.placeholder=Select Customer
-addjob.customer.unnamed=Unnamed Customer
+addjob.customer.label=Principal
+addjob.customer.placeholder=Select principal
+addjob.customer.unnamed=Unnamed principal
 addjob.button.clearfields=Clear Fields
 addjob.button.submit=Create Job
 addjob.address.salutation=Salutation
@@ -440,6 +440,10 @@ addjob.salutation.mr=Mr
 addjob.salutation.ms=Ms
 addjob.salutation.other=Other
 addjob.address.company.placeholder=Enter company
+addjob.address.pickup.label=Pickup address
+addjob.address.pickup.placeholder=Select or enter pickup address
+addjob.address.delivery.label=Delivery address
+addjob.address.delivery.placeholder=Select or enter delivery address
 addjob.address.street.placeholder=Enter street
 addjob.address.housenumber=House Number
 addjob.address.addition.placeholder=Address suffix
@@ -460,6 +464,8 @@ addjob.station.max.reached=Maximum number of 25 delivery stations reached
 addjob.station.unused=Not used
 addjob.appointment.delivery.info=Delivery dates are set directly in the delivery stations.
 addjob.tab.addresses=Client & Addresses
+addjob.tab.pickup.address=Principal & Pickup Address
+addjob.tab.delivery.address=Delivery Address
 addjob.tab.appointments=Appointments & Processing
 addjob.tab.cargo=Cargo
 addjob.tab.tasks=Tasks
@@ -621,6 +627,9 @@ jobsummary.dialog.manualcomplete.reason.required=Please enter a reason
 jobsummary.dialog.manualcomplete.cancel=Cancel
 jobsummary.dialog.manualcomplete.confirm=Accept
 jobsummary.history.manualcomplete.reason=Manually completed
+jobmanualcomplete.route.hours=Hours
+jobmanualcomplete.route.minutes=Minutes
+jobmanualcomplete.route.manual.hint=No route data available – please enter distance and duration manually.
 
 # Jobs
 jobs.title=Jobs
@@ -697,6 +706,72 @@ invoices.column.amount=Amount
 invoices.column.description=Description
 invoices.empty=No invoices have been created yet.
 invoices.notification.pdf.missing=No PDF is stored for this invoice.
+invoices.notification.pdf.error=Failed to display PDF: {0}
+invoices.column.status=Status
+invoices.column.type=Type
+invoices.column.actions=Actions
+invoices.disclaimer=Note: Legal retention obligations remain with the issuer. An already issued invoice is never overwritten — corrections are made through a correction document or cancellation invoice that explicitly references the original.
+invoices.status.draft=Draft
+invoices.status.issued=Issued
+invoices.status.sent=Sent
+invoices.status.cancelled=Cancelled
+invoices.status.corrected=Corrected
+invoices.type.invoice=Invoice
+invoices.type.cancellation=Cancellation invoice
+invoices.type.correction=Correction document
+invoices.action.view=View PDF
+invoices.action.history=History
+invoices.action.marksent=Mark as sent
+invoices.action.correct=Correct
+invoices.action.cancel=Cancel
+invoices.notification.sent=Invoice marked as sent.
+invoices.notification.cancelled=Cancellation document {0} created.
+invoices.notification.corrected=Correction document {0} created.
+invoices.notification.error=Action failed: {0}
+invoices.cancel.title=Cancel invoice {0}
+invoices.cancel.hint=The original invoice remains visible. A separate cancellation document with its own number will be created, explicitly referencing the original invoice.
+invoices.cancel.reason=Reason for cancellation
+invoices.cancel.reason.required=Please provide a reason.
+invoices.cancel.confirm=Create cancellation document
+invoices.correct.title=Correct invoice {0}
+invoices.correct.hint=A correction document is intended for formal errors only (e.g. address, delivery date). The original invoice remains visible and the correction document refers to it explicitly.
+invoices.correct.fields=Corrected information
+invoices.correct.fields.helper=Describe which fields are added or replaced.
+invoices.correct.fields.required=Please describe the corrected information.
+invoices.correct.reason=Reason for correction
+invoices.correct.confirm=Create correction document
+invoices.history.title=History for invoice {0}
+invoices.history.log=Audit log
+invoices.history.empty=No entries available.
+invoices.history.original=Original invoice
+invoices.history.cancellation=Cancellation document
+invoices.history.correction=Correction document
+invoices.history.replacement=Replacement invoice
+invoices.audit.action.created_draft=Draft created
+invoices.audit.action.updated_draft=Draft updated
+invoices.audit.action.issued=Issued
+invoices.audit.action.sent=Sent
+invoices.audit.action.cancelled=Cancelled
+invoices.audit.action.corrected=Corrected
+invoices.audit.action.replaced=Replaced by new invoice
+invoices.audit.action.deleted_draft=Draft deleted
+invoices.audit.action.payment_recorded=Payment recorded
+invoices.audit.resulting=Resulting document: {0}
+invoices.payment.unpaid=Open
+invoices.payment.partially_paid=Partially paid
+invoices.payment.paid=Paid
+invoices.payment.overpaid=Overpaid
+invoices.payment.refund_due=Refund due
+invoices.action.payment=Record payment
+invoices.action.export=Export
+invoices.payment.title=Payment for invoice {0}
+invoices.payment.hint=Outstanding balance: {0}. Negative amounts can be recorded for corrections.
+invoices.payment.amount=Amount
+invoices.payment.amount.required=Please enter a non-zero amount.
+invoices.payment.reference=Payment reference (e.g. statement, booking ID)
+invoices.payment.reason=Note
+invoices.payment.confirm=Record payment
+invoices.notification.payment=Payment recorded.
 
 # My Invoices
 myinvoices.title=Invoices

backend/src/main/resources/messages_es.properties

@@ -428,9 +428,9 @@ messages.sender.unknown=Remitente desconocido
 
 # Add Job
 addjob.title=Crear nuevo pedido
-addjob.customer.label=Cliente
-addjob.customer.placeholder=Seleccionar cliente
-addjob.customer.unnamed=Cliente sin nombre
+addjob.customer.label=Ordenante
+addjob.customer.placeholder=Seleccionar ordenante
+addjob.customer.unnamed=Ordenante sin nombre
 addjob.button.clearfields=Vaciar campos
 addjob.button.submit=Crear pedido
 addjob.address.salutation=Tratamiento
@@ -439,6 +439,10 @@ addjob.salutation.mr=Sr.
 addjob.salutation.ms=Sra.
 addjob.salutation.other=Otro
 addjob.address.company.placeholder=Introducir empresa
+addjob.address.pickup.label=Direcci\u00f3n de recogida
+addjob.address.pickup.placeholder=Seleccionar o introducir direcci\u00f3n de recogida
+addjob.address.delivery.label=Direcci\u00f3n de entrega
+addjob.address.delivery.placeholder=Seleccionar o introducir direcci\u00f3n de entrega
 addjob.address.street.placeholder=Introducir calle
 addjob.address.housenumber=N\u00famero de casa
 addjob.address.addition.placeholder=Complemento de direcci\u00f3n
@@ -459,6 +463,8 @@ addjob.station.max.reached=Se ha alcanzado el n\u00famero m\u00e1ximo de 25 esta
 addjob.station.unused=No utilizada
 addjob.appointment.delivery.info=Las fechas de entrega se establecen directamente en las estaciones de entrega.
 addjob.tab.addresses=Cliente y direcciones
+addjob.tab.pickup.address=Ordenante y direcci\u00f3n de recogida
+addjob.tab.delivery.address=Direcci\u00f3n de entrega
 addjob.tab.appointments=Citas y procesamiento
 addjob.tab.cargo=Carga
 addjob.tab.tasks=Tareas
@@ -620,6 +626,9 @@ jobsummary.dialog.manualcomplete.reason.required=Por favor, introduzca un motivo
 jobsummary.dialog.manualcomplete.cancel=Cancelar
 jobsummary.dialog.manualcomplete.confirm=Aceptar
 jobsummary.history.manualcomplete.reason=Finalizado manualmente
+jobmanualcomplete.route.hours=Horas
+jobmanualcomplete.route.minutes=Minutos
+jobmanualcomplete.route.manual.hint=No hay datos de ruta disponibles – introduzca la distancia y la duración manualmente.
 
 # Jobs
 jobs.title=Pedidos

backend/src/main/resources/messages_fr.properties

@@ -428,9 +428,9 @@ messages.sender.unknown=Exp\u00e9diteur inconnu
 
 # Add Job
 addjob.title=Cr\u00e9er une nouvelle mission
-addjob.customer.label=Client
-addjob.customer.placeholder=S\u00e9lectionner un client
-addjob.customer.unnamed=Client sans nom
+addjob.customer.label=Donneur d'ordre
+addjob.customer.placeholder=S\u00e9lectionner le donneur d'ordre
+addjob.customer.unnamed=Donneur d'ordre sans nom
 addjob.button.clearfields=Vider les champs
 addjob.button.submit=Cr\u00e9er la mission
 addjob.address.salutation=Civilit\u00e9
@@ -439,6 +439,10 @@ addjob.salutation.mr=Monsieur
 addjob.salutation.ms=Madame
 addjob.salutation.other=Autre
 addjob.address.company.placeholder=Saisir l'entreprise
+addjob.address.pickup.label=Adresse d'enl\u00e8vement
+addjob.address.pickup.placeholder=S\u00e9lectionner ou saisir l'adresse d'enl\u00e8vement
+addjob.address.delivery.label=Adresse de livraison
+addjob.address.delivery.placeholder=S\u00e9lectionner ou saisir l'adresse de livraison
 addjob.address.street.placeholder=Saisir la rue
 addjob.address.housenumber=Num\u00e9ro
 addjob.address.addition.placeholder=Compl\u00e9ment d'adresse
@@ -459,6 +463,8 @@ addjob.station.max.reached=Nombre maximum de 25 stations de livraison atteint
 addjob.station.unused=Non utilis\u00e9e
 addjob.appointment.delivery.info=Les dates de livraison sont d\u00e9finies directement dans les stations de livraison.
 addjob.tab.addresses=Donneur d'ordre & adresses
+addjob.tab.pickup.address=Donneur d'ordre & adresse d'enl\u00e8vement
+addjob.tab.delivery.address=Adresse de livraison
 addjob.tab.appointments=Rendez-vous & traitement
 addjob.tab.cargo=Fret
 addjob.tab.tasks=T\u00e2ches
@@ -620,6 +626,9 @@ jobsummary.dialog.manualcomplete.reason.required=Veuillez saisir un motif
 jobsummary.dialog.manualcomplete.cancel=Annuler
 jobsummary.dialog.manualcomplete.confirm=Accepter
 jobsummary.history.manualcomplete.reason=Termin\u00e9 manuellement
+jobmanualcomplete.route.hours=Heures
+jobmanualcomplete.route.minutes=Minutes
+jobmanualcomplete.route.manual.hint=Aucune donn\u00e9e d'itin\u00e9raire disponible \u2013 veuillez saisir la distance et la dur\u00e9e manuellement.
 
 # Jobs
 jobs.title=Missions

backend/src/main/resources/messages_lt.properties

@@ -428,9 +428,9 @@ messages.sender.unknown=Nežinomas siuntėjas
 
 # Add Job
 addjob.title=Sukurti naują užsakymą
-addjob.customer.label=Klientas
-addjob.customer.placeholder=Pasirinkite klientą
-addjob.customer.unnamed=Klientas be pavadinimo
+addjob.customer.label=Užsakovas
+addjob.customer.placeholder=Pasirinkite užsakovą
+addjob.customer.unnamed=Neįvardytas užsakovas
 addjob.button.clearfields=Išvalyti laukus
 addjob.button.submit=Sukurti užsakymą
 addjob.address.salutation=Kreipinys
@@ -439,6 +439,10 @@ addjob.salutation.mr=Ponas
 addjob.salutation.ms=Ponia
 addjob.salutation.other=Kita
 addjob.address.company.placeholder=Įveskite įmonę
+addjob.address.pickup.label=Atsiėmimo adresas
+addjob.address.pickup.placeholder=Pasirinkti arba įvesti atsiėmimo adresą
+addjob.address.delivery.label=Pristatymo adresas
+addjob.address.delivery.placeholder=Pasirinkti arba įvesti pristatymo adresą
 addjob.address.street.placeholder=Įveskite gatvę
 addjob.address.housenumber=Namo numeris
 addjob.address.addition.placeholder=Adreso priedas
@@ -459,6 +463,8 @@ addjob.station.max.reached=Pasiektas maksimalus 25 pristatymo stočių skaičius
 addjob.station.unused=Nenaudojama
 addjob.appointment.delivery.info=Pristatymo terminai nustatomi tiesiogiai pristatymo stotyse.
 addjob.tab.addresses=Užsakovas ir adresai
+addjob.tab.pickup.address=Užsakovas ir atsiėmimo adresas
+addjob.tab.delivery.address=Pristatymo adresas
 addjob.tab.appointments=Terminai ir apdorojimas
 addjob.tab.cargo=Krovinys
 addjob.tab.tasks=Užduotys
@@ -620,6 +626,9 @@ jobsummary.dialog.manualcomplete.reason.required=Prašome įvesti priežastį
 jobsummary.dialog.manualcomplete.cancel=Atšaukti
 jobsummary.dialog.manualcomplete.confirm=Priimti
 jobsummary.history.manualcomplete.reason=Užbaigta rankiniu būdu
+jobmanualcomplete.route.hours=Valandos
+jobmanualcomplete.route.minutes=Minutės
+jobmanualcomplete.route.manual.hint=Maršruto duomenų nėra – prašome įvesti atstumą ir trukmę rankiniu būdu.
 
 # Jobs
 jobs.title=Užsakymai

backend/src/main/resources/messages_lv.properties

@@ -428,9 +428,9 @@ messages.sender.unknown=Nezināms sūtītājs
 
 # Add Job
 addjob.title=Izveidot jaunu uzdevumu
-addjob.customer.label=Klients
-addjob.customer.placeholder=Izvēlēties klientu
-addjob.customer.unnamed=Nenosaukts klients
+addjob.customer.label=Pasūtītājs
+addjob.customer.placeholder=Izvēlēties pasūtītāju
+addjob.customer.unnamed=Nenosaukts pasūtītājs
 addjob.button.clearfields=Notīrīt laukus
 addjob.button.submit=Izveidot uzdevumu
 addjob.address.salutation=Uzruna
@@ -439,6 +439,10 @@ addjob.salutation.mr=Kungs
 addjob.salutation.ms=Kundze
 addjob.salutation.other=Cits
 addjob.address.company.placeholder=Ievadiet uzņēmumu
+addjob.address.pickup.label=Saņemšanas adrese
+addjob.address.pickup.placeholder=Izvēlēties vai ievadīt saņemšanas adresi
+addjob.address.delivery.label=Piegādes adrese
+addjob.address.delivery.placeholder=Izvēlēties vai ievadīt piegādes adresi
 addjob.address.street.placeholder=Ievadiet ielu
 addjob.address.housenumber=Mājas numurs
 addjob.address.addition.placeholder=Adreses papildinājums
@@ -459,6 +463,8 @@ addjob.station.max.reached=Sasniegts maksimālais piegādes staciju skaits - 25
 addjob.station.unused=Netiek izmantots
 addjob.appointment.delivery.info=Piegādes termiņi tiek noteikti tieši piegādes stacijās.
 addjob.tab.addresses=Pasūtītājs un adreses
+addjob.tab.pickup.address=Pasūtītājs un saņemšanas adrese
+addjob.tab.delivery.address=Piegādes adrese
 addjob.tab.appointments=Termiņi un apstrāde
 addjob.tab.cargo=Krava
 addjob.tab.tasks=Uzdevuma darbības
@@ -620,6 +626,9 @@ jobsummary.dialog.manualcomplete.reason.required=Lūdzu, ievadiet pamatojumu
 jobsummary.dialog.manualcomplete.cancel=Atcelt
 jobsummary.dialog.manualcomplete.confirm=Apstiprināt
 jobsummary.history.manualcomplete.reason=Pabeigts manuāli
+jobmanualcomplete.route.hours=Stundas
+jobmanualcomplete.route.minutes=Minūtes
+jobmanualcomplete.route.manual.hint=Maršruta dati nav pieejami – lūdzu, manuāli ievadiet attālumu un ilgumu.
 
 # Jobs
 jobs.title=Uzdevumi

backend/src/main/resources/messages_pl.properties

@@ -428,9 +428,9 @@ messages.sender.unknown=Nieznany nadawca
 
 # Add Job
 addjob.title=Dodaj nowe zlecenie
-addjob.customer.label=Klient
-addjob.customer.placeholder=Wybierz klienta
-addjob.customer.unnamed=Klient bez nazwy
+addjob.customer.label=Zleceniodawca
+addjob.customer.placeholder=Wybierz zleceniodawcę
+addjob.customer.unnamed=Nienazwany zleceniodawca
 addjob.button.clearfields=Wyczy\u015b\u0107 pola
 addjob.button.submit=Utw\u00f3rz zlecenie
 addjob.address.salutation=Zwrot grzeczno\u015bciowy
@@ -439,6 +439,10 @@ addjob.salutation.mr=Pan
 addjob.salutation.ms=Pani
 addjob.salutation.other=Inna
 addjob.address.company.placeholder=Wprowad\u017a firm\u0119
+addjob.address.pickup.label=Adres odbioru
+addjob.address.pickup.placeholder=Wybierz lub wprowad\u017a adres odbioru
+addjob.address.delivery.label=Adres dostawy
+addjob.address.delivery.placeholder=Wybierz lub wprowad\u017a adres dostawy
 addjob.address.street.placeholder=Wprowad\u017a ulic\u0119
 addjob.address.housenumber=Numer domu
 addjob.address.addition.placeholder=Dodatek do adresu
@@ -459,6 +463,8 @@ addjob.station.max.reached=Osi\u0105gni\u0119to maksymaln\u0105 liczb\u0119 25 s
 addjob.station.unused=Nieu\u017cywana
 addjob.appointment.delivery.info=Terminy dostaw s\u0105 ustalane bezpo\u015brednio w stacjach dostawy.
 addjob.tab.addresses=Zleceniodawca i adresy
+addjob.tab.pickup.address=Zleceniodawca i adres odbioru
+addjob.tab.delivery.address=Adres dostawy
 addjob.tab.appointments=Terminy i przetwarzanie
 addjob.tab.cargo=\u0141adunek
 addjob.tab.tasks=Zadania
@@ -620,6 +626,9 @@ jobsummary.dialog.manualcomplete.reason.required=Prosz\u0119 poda\u0107 uzasadni
 jobsummary.dialog.manualcomplete.cancel=Anuluj
 jobsummary.dialog.manualcomplete.confirm=Akceptuj
 jobsummary.history.manualcomplete.reason=Zako\u0144czono r\u0119cznie
+jobmanualcomplete.route.hours=Godziny
+jobmanualcomplete.route.minutes=Minuty
+jobmanualcomplete.route.manual.hint=Brak danych trasy \u2013 prosz\u0119 r\u0119cznie poda\u0107 odleg\u0142o\u015b\u0107 i czas trwania.
 
 # Jobs
 jobs.title=Zlecenia

backend/src/main/resources/messages_ru.properties

@@ -428,9 +428,9 @@ messages.sender.unknown=Неизвестный отправитель
 
 # Add Job
 addjob.title=Создать новый заказ
-addjob.customer.label=Клиент
-addjob.customer.placeholder=Выберите клиента
-addjob.customer.unnamed=Безымянный клиент
+addjob.customer.label=Заказчик
+addjob.customer.placeholder=Выберите заказчика
+addjob.customer.unnamed=Безымянный заказчик
 addjob.button.clearfields=Очистить поля
 addjob.button.submit=Создать заказ
 addjob.address.salutation=Обращение
@@ -439,6 +439,10 @@ addjob.salutation.mr=Господин
 addjob.salutation.ms=Госпожа
 addjob.salutation.other=Другое
 addjob.address.company.placeholder=Введите компанию
+addjob.address.pickup.label=Адрес забора
+addjob.address.pickup.placeholder=Выберите или введите адрес забора
+addjob.address.delivery.label=Адрес доставки
+addjob.address.delivery.placeholder=Выберите или введите адрес доставки
 addjob.address.street.placeholder=Введите улицу
 addjob.address.housenumber=Номер дома
 addjob.address.addition.placeholder=Дополнение к адресу
@@ -459,6 +463,8 @@ addjob.station.max.reached=Достигнуто максимальное кол
 addjob.station.unused=Не используется
 addjob.appointment.delivery.info=Сроки доставки устанавливаются непосредственно в станциях доставки.
 addjob.tab.addresses=Заказчик и адреса
+addjob.tab.pickup.address=Заказчик и адрес забора
+addjob.tab.delivery.address=Адрес доставки
 addjob.tab.appointments=Сроки и обработка
 addjob.tab.cargo=Груз
 addjob.tab.tasks=Задачи
@@ -620,6 +626,9 @@ jobsummary.dialog.manualcomplete.reason.required=Пожалуйста, укаж
 jobsummary.dialog.manualcomplete.cancel=Отмена
 jobsummary.dialog.manualcomplete.confirm=Принять
 jobsummary.history.manualcomplete.reason=Завершено вручную
+jobmanualcomplete.route.hours=Часы
+jobmanualcomplete.route.minutes=Минуты
+jobmanualcomplete.route.manual.hint=Данные маршрута отсутствуют — пожалуйста, введите расстояние и продолжительность вручную.
 
 # Jobs
 jobs.title=Заказы

backend/src/main/resources/messages_tr.properties

@@ -428,9 +428,9 @@ messages.sender.unknown=Bilinmeyen G\u00f6nderici
 
 # Add Job
 addjob.title=Yeni \u0130\u015f Olu\u015ftur
-addjob.customer.label=M\u00fc\u015fteri
-addjob.customer.placeholder=M\u00fc\u015fteri Se\u00e7in
-addjob.customer.unnamed=\u0130simsiz M\u00fc\u015fteri
+addjob.customer.label=Sipari\u015f veren
+addjob.customer.placeholder=Sipari\u015f vereni se\u00e7
+addjob.customer.unnamed=\u0130simsiz sipari\u015f veren
 addjob.button.clearfields=Alanlar\u0131 Temizle
 addjob.button.submit=\u0130\u015f Olu\u015ftur
 addjob.address.salutation=Hitap
@@ -439,6 +439,10 @@ addjob.salutation.mr=Bay
 addjob.salutation.ms=Bayan
 addjob.salutation.other=Di\u011fer
 addjob.address.company.placeholder=\u015eirketi girin
+addjob.address.pickup.label=Al\u0131m adresi
+addjob.address.pickup.placeholder=Al\u0131m adresi se\u00e7in veya girin
+addjob.address.delivery.label=Teslimat adresi
+addjob.address.delivery.placeholder=Teslimat adresi se\u00e7in veya girin
 addjob.address.street.placeholder=Soka\u011f\u0131 girin
 addjob.address.housenumber=Kap\u0131 Numaras\u0131
 addjob.address.addition.placeholder=Adres eki
@@ -459,6 +463,8 @@ addjob.station.max.reached=Maksimum 25 teslimat istasyonu s\u0131n\u0131r\u0131n
 addjob.station.unused=Kullan\u0131lm\u0131yor
 addjob.appointment.delivery.info=Teslimat tarihleri do\u011frudan teslimat istasyonlar\u0131nda belirlenir.
 addjob.tab.addresses=M\u00fc\u015fteri & Adresler
+addjob.tab.pickup.address=Sipari\u015f veren ve al\u0131m adresi
+addjob.tab.delivery.address=Teslimat adresi
 addjob.tab.appointments=Randevular & \u0130\u015fleme
 addjob.tab.cargo=Kargo
 addjob.tab.tasks=G\u00f6revler
@@ -620,6 +626,9 @@ jobsummary.dialog.manualcomplete.reason.required=Lütfen bir gerekçe girin
 jobsummary.dialog.manualcomplete.cancel=İptal
 jobsummary.dialog.manualcomplete.confirm=Kabul et
 jobsummary.history.manualcomplete.reason=Manuel olarak tamamlandı
+jobmanualcomplete.route.hours=Saat
+jobmanualcomplete.route.minutes=Dakika
+jobmanualcomplete.route.manual.hint=Rota verisi mevcut değil – lütfen mesafeyi ve süreyi elle girin.
 
 # Jobs
 jobs.title=\u0130\u015fler

backend/src/test/java/de/assecutor/votianlt/service/InvoiceComplianceValidatorTest.java

@@ -0,0 +1,304 @@
+package de.assecutor.votianlt.service;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.assertj.core.api.Assertions.catchThrowableOfType;
+
+import de.assecutor.votianlt.model.invoices.CustomerInvoice;
+import de.assecutor.votianlt.model.invoices.CustomerInvoiceItem;
+import de.assecutor.votianlt.model.invoices.InvoiceType;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.math.BigDecimal;
+import java.time.LocalDate;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Pflichtangaben-Validierung nach § 14 UStG. Jeder Test mutiert exakt eine
+ * Eigenschaft der Referenzrechnung — so bleibt sichtbar, welche Regel gerade
+ * geprüft wird, und die Tests fungieren gleichzeitig als ausführbare
+ * Spezifikation.
+ */
+class InvoiceComplianceValidatorTest {
+
+    private InvoiceComplianceValidator validator;
+
+    @BeforeEach
+    void setUp() {
+        validator = new InvoiceComplianceValidator();
+    }
+
+    @Test
+    void acceptsCompleteInvoice() {
+        CustomerInvoice invoice = validInvoice();
+        validator.validateForIssuance(invoice);
+    }
+
+    @Test
+    void rejectsMissingInvoiceNumber() {
+        CustomerInvoice invoice = validInvoice();
+        invoice.setInvoiceNumber("   ");
+        assertSingleViolation(invoice, "Rechnungsnummer fehlt");
+    }
+
+    @Test
+    void rejectsMissingInvoiceDate() {
+        CustomerInvoice invoice = validInvoice();
+        invoice.setInvoiceDate(null);
+        assertSingleViolation(invoice, "Rechnungsdatum");
+    }
+
+    @Test
+    void rejectsMissingDeliveryDate() {
+        CustomerInvoice invoice = validInvoice();
+        invoice.setDeliveryDate(null);
+        assertSingleViolation(invoice, "Leistungsdatum");
+    }
+
+    @Test
+    void rejectsMissingSenderName() {
+        CustomerInvoice invoice = validInvoice();
+        invoice.setSenderName(null);
+        assertSingleViolation(invoice, "Name des Leistenden");
+    }
+
+    @Test
+    void rejectsIncompleteSenderAddress() {
+        CustomerInvoice invoice = validInvoice();
+        invoice.setSenderPostcode("");
+        assertSingleViolation(invoice, "Anschrift des Leistenden");
+    }
+
+    @Test
+    void rejectsMissingSenderTaxIdentification() {
+        CustomerInvoice invoice = validInvoice();
+        invoice.setSenderTaxNumber(null);
+        invoice.setSenderVatId(null);
+        assertSingleViolation(invoice, "Steuernummer oder USt-IdNr");
+    }
+
+    @Test
+    void acceptsSenderWithOnlyTaxNumber() {
+        CustomerInvoice invoice = validInvoice();
+        invoice.setSenderVatId(null);
+        validator.validateForIssuance(invoice);
+    }
+
+    @Test
+    void acceptsSenderWithOnlyVatId() {
+        CustomerInvoice invoice = validInvoice();
+        invoice.setSenderTaxNumber(null);
+        validator.validateForIssuance(invoice);
+    }
+
+    @Test
+    void rejectsMissingRecipientName() {
+        CustomerInvoice invoice = validInvoice();
+        invoice.setRecipientName(null);
+        assertSingleViolation(invoice, "Name des Leistungsempfängers");
+    }
+
+    @Test
+    void rejectsIncompleteRecipientAddress() {
+        CustomerInvoice invoice = validInvoice();
+        invoice.setRecipientCity(null);
+        assertSingleViolation(invoice, "Anschrift des Leistungsempfängers");
+    }
+
+    @Test
+    void rejectsEmptyItems() {
+        CustomerInvoice invoice = validInvoice();
+        invoice.setItems(new ArrayList<>());
+        assertSingleViolation(invoice, "Keine Positionen erfasst");
+    }
+
+    @Test
+    void rejectsItemWithoutDescription() {
+        CustomerInvoice invoice = validInvoice();
+        invoice.getItems().get(0).setDescription("");
+        assertSingleViolation(invoice, "Bezeichnung der Leistung fehlt");
+    }
+
+    @Test
+    void rejectsItemWithZeroQuantity() {
+        CustomerInvoice invoice = validInvoice();
+        CustomerInvoiceItem item = invoice.getItems().get(0);
+        item.setQuantity(BigDecimal.ZERO);
+        // Zwingt netTotal = 0, damit nur die Mengenregel anschlägt und nicht zusätzlich
+        // die Konsistenzprüfung der Summen.
+        item.setNetTotal(BigDecimal.ZERO);
+        invoice.setNetAmount(BigDecimal.ZERO);
+        invoice.setVatAmount(BigDecimal.ZERO);
+        invoice.setTotalAmount(BigDecimal.ZERO);
+        // VAT-Hinweis muss bei 0 % aber gesetzt sein, sonst lösen wir zwei Verstöße aus.
+        invoice.setVatRate(new BigDecimal("0.19"));
+        assertSingleViolation(invoice, "Menge muss größer 0");
+    }
+
+    @Test
+    void rejectsItemWithNegativeUnitPrice() {
+        CustomerInvoice invoice = validInvoice();
+        invoice.getItems().get(0).setUnitPrice(new BigDecimal("-5.00"));
+        InvoiceComplianceException ex = catchThrowableOfType(
+                () -> validator.validateForIssuance(invoice), InvoiceComplianceException.class);
+        assertThat(ex).isNotNull();
+        assertThat(ex.getViolations()).anyMatch(v -> v.contains("Einzelpreis"));
+    }
+
+    @Test
+    void rejectsInconsistentTotals() {
+        CustomerInvoice invoice = validInvoice();
+        invoice.setTotalAmount(new BigDecimal("999.99"));
+        InvoiceComplianceException ex = catchThrowableOfType(
+                () -> validator.validateForIssuance(invoice), InvoiceComplianceException.class);
+        assertThat(ex).isNotNull();
+        assertThat(ex.getViolations()).anyMatch(v -> v.contains("Bruttobetrag passt nicht"));
+    }
+
+    @Test
+    void rejectsItemSumMismatchingNet() {
+        CustomerInvoice invoice = validInvoice();
+        // Items summieren sich weiterhin auf 100.00, aber das deklarierte Netto wird verstellt.
+        invoice.setNetAmount(new BigDecimal("80.00"));
+        invoice.setVatAmount(new BigDecimal("15.20"));
+        invoice.setTotalAmount(new BigDecimal("95.20"));
+        InvoiceComplianceException ex = catchThrowableOfType(
+                () -> validator.validateForIssuance(invoice), InvoiceComplianceException.class);
+        assertThat(ex).isNotNull();
+        assertThat(ex.getViolations()).anyMatch(v -> v.contains("Summe der Positionen"));
+    }
+
+    @Test
+    void rejectsMissingVatRate() {
+        CustomerInvoice invoice = validInvoice();
+        invoice.setVatRate(null);
+        assertSingleViolation(invoice, "Steuersatz fehlt");
+    }
+
+    @Test
+    void rejectsZeroVatWithoutLegalNotice() {
+        CustomerInvoice invoice = zeroVatInvoice();
+        invoice.setReverseChargeNote(null);
+        invoice.setLegalNotes(null);
+        assertSingleViolation(invoice, "Bei 0 % USt ist ein rechtlicher Hinweis erforderlich");
+    }
+
+    @Test
+    void acceptsZeroVatWithReverseChargeNote() {
+        CustomerInvoice invoice = zeroVatInvoice();
+        invoice.setReverseChargeNote("Steuerschuldnerschaft des Leistungsempfängers (§ 13b UStG).");
+        invoice.setLegalNotes(null);
+        validator.validateForIssuance(invoice);
+    }
+
+    @Test
+    void acceptsZeroVatWithLegalNotes() {
+        CustomerInvoice invoice = zeroVatInvoice();
+        invoice.setReverseChargeNote(null);
+        invoice.setLegalNotes("Kleinunternehmer im Sinne des § 19 Abs. 1 UStG — keine Umsatzsteuer ausgewiesen.");
+        validator.validateForIssuance(invoice);
+    }
+
+    @Test
+    void rejectsMismatchingVatAmountForNonZeroRate() {
+        CustomerInvoice invoice = validInvoice();
+        // Erwartet wären 19,00 € — wir tragen 25,00 € ein.
+        invoice.setVatAmount(new BigDecimal("25.00"));
+        invoice.setTotalAmount(new BigDecimal("125.00"));
+        InvoiceComplianceException ex = catchThrowableOfType(
+                () -> validator.validateForIssuance(invoice), InvoiceComplianceException.class);
+        assertThat(ex).isNotNull();
+        assertThat(ex.getViolations()).anyMatch(v -> v.contains("Steuerbetrag"));
+    }
+
+    @Test
+    void collectsAllViolationsInOnePass() {
+        CustomerInvoice invoice = validInvoice();
+        invoice.setInvoiceNumber(null);
+        invoice.setSenderName(null);
+        invoice.setItems(new ArrayList<>());
+        InvoiceComplianceException ex = catchThrowableOfType(
+                () -> validator.validateForIssuance(invoice), InvoiceComplianceException.class);
+        assertThat(ex).isNotNull();
+        assertThat(ex.getViolations())
+                .as("Validator soll alle Verstöße sammeln, nicht beim ersten abbrechen")
+                .hasSizeGreaterThanOrEqualTo(3);
+    }
+
+    @Test
+    void cancellationIsNotValidatedHere() {
+        CustomerInvoice invoice = validInvoice();
+        invoice.setType(InvoiceType.CANCELLATION);
+        invoice.setItems(new ArrayList<>()); // wäre für reguläre Rechnung ein Fehler
+        validator.validateForIssuance(invoice);
+    }
+
+    @Test
+    void correctionIsNotValidatedHere() {
+        CustomerInvoice invoice = validInvoice();
+        invoice.setType(InvoiceType.CORRECTION);
+        invoice.setSenderName(null); // wäre für reguläre Rechnung ein Fehler
+        validator.validateForIssuance(invoice);
+    }
+
+    @Test
+    void nullInvoiceIsRejectedDirectly() {
+        assertThatThrownBy(() -> validator.validateForIssuance(null))
+                .isInstanceOf(IllegalArgumentException.class);
+    }
+
+    private void assertSingleViolation(CustomerInvoice invoice, String fragment) {
+        InvoiceComplianceException ex = catchThrowableOfType(
+                () -> validator.validateForIssuance(invoice), InvoiceComplianceException.class);
+        assertThat(ex).as("erwartete InvoiceComplianceException").isNotNull();
+        assertThat(ex.getViolations())
+                .as("Verstoß mit Fragment '%s' erwartet, war: %s", fragment, ex.getViolations())
+                .anyMatch(v -> v.contains(fragment));
+    }
+
+    private CustomerInvoice validInvoice() {
+        CustomerInvoice invoice = new CustomerInvoice();
+        invoice.setType(InvoiceType.INVOICE);
+        invoice.setInvoiceNumber("R-2026-0001");
+        invoice.setInvoiceDate(LocalDate.of(2026, 5, 3));
+        invoice.setDeliveryDate(LocalDate.of(2026, 5, 3));
+
+        invoice.setSenderName("Votianlt Test GmbH");
+        invoice.setSenderAddress("Teststraße 1");
+        invoice.setSenderPostcode("12345");
+        invoice.setSenderCity("Berlin");
+        invoice.setSenderCountry("DE");
+        invoice.setSenderTaxNumber("12/345/67890");
+        invoice.setSenderVatId("DE123456789");
+
+        invoice.setRecipientName("Empfänger AG");
+        invoice.setRecipientAddress("Kundenweg 2");
+        invoice.setRecipientPostcode("54321");
+        invoice.setRecipientCity("Hamburg");
+        invoice.setRecipientCountry("DE");
+
+        CustomerInvoiceItem item = new CustomerInvoiceItem(BigDecimal.ONE, "h", "Beratung",
+                new BigDecimal("100.00"), new BigDecimal("0.19"));
+        invoice.setItems(new ArrayList<>(List.of(item)));
+
+        invoice.setNetAmount(new BigDecimal("100.00"));
+        invoice.setVatRate(new BigDecimal("0.19"));
+        invoice.setVatAmount(new BigDecimal("19.00"));
+        invoice.setTotalAmount(new BigDecimal("119.00"));
+        return invoice;
+    }
+
+    private CustomerInvoice zeroVatInvoice() {
+        CustomerInvoice invoice = validInvoice();
+        invoice.setVatRate(BigDecimal.ZERO);
+        invoice.setVatAmount(BigDecimal.ZERO);
+        invoice.setTotalAmount(invoice.getNetAmount());
+        CustomerInvoiceItem item = invoice.getItems().get(0);
+        item.setVatRate(BigDecimal.ZERO);
+        item.setVatAmount(BigDecimal.ZERO);
+        item.setGrossTotal(item.getNetTotal());
+        return invoice;
+    }
+}

backend/src/test/java/de/assecutor/votianlt/service/InvoiceNumberAuditServiceTest.java

@@ -0,0 +1,171 @@
+package de.assecutor.votianlt.service;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import de.assecutor.votianlt.model.invoices.CustomerInvoice;
+import de.assecutor.votianlt.model.invoices.InvoiceNumberReservation;
+import de.assecutor.votianlt.model.invoices.InvoiceNumberReservationStatus;
+import de.assecutor.votianlt.repository.InvoiceNumberReservationRepository;
+import org.bson.types.ObjectId;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.ArgumentCaptor;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+import java.util.List;
+import java.util.Optional;
+
+@ExtendWith(MockitoExtension.class)
+class InvoiceNumberAuditServiceTest {
+
+    @Mock
+    private InvoiceNumberReservationRepository repository;
+
+    private InvoiceNumberAuditService service;
+
+    private final ObjectId userId = new ObjectId();
+
+    @BeforeEach
+    void setUp() {
+        service = new InvoiceNumberAuditService(repository);
+    }
+
+    @Test
+    void markUsedTransitionsExistingReservation() {
+        InvoiceNumberReservation reservation = reservation("R-2026-000010", 10L,
+                InvoiceNumberReservationStatus.RESERVED);
+        when(repository.findByUserIdAndNumber(userId, "R-2026-000010")).thenReturn(Optional.of(reservation));
+        when(repository.save(any(InvoiceNumberReservation.class))).thenAnswer(inv -> inv.getArgument(0));
+
+        CustomerInvoice invoice = invoice("R-2026-000010", "invoice-id-42");
+        service.markUsed(invoice);
+
+        ArgumentCaptor<InvoiceNumberReservation> captor = ArgumentCaptor.forClass(InvoiceNumberReservation.class);
+        verify(repository).save(captor.capture());
+        InvoiceNumberReservation saved = captor.getValue();
+        assertThat(saved.getStatus()).isEqualTo(InvoiceNumberReservationStatus.USED);
+        assertThat(saved.getInvoiceId()).isEqualTo("invoice-id-42");
+        assertThat(saved.getUsedAt()).isNotNull();
+    }
+
+    @Test
+    void markUsedBootstrapsReservationForLegacyInvoiceWithoutPriorReservation() {
+        when(repository.findByUserIdAndNumber(userId, "RE-2024-0007")).thenReturn(Optional.empty());
+        when(repository.save(any(InvoiceNumberReservation.class))).thenAnswer(inv -> inv.getArgument(0));
+
+        service.markUsed(invoice("RE-2024-0007", "legacy-invoice"));
+
+        ArgumentCaptor<InvoiceNumberReservation> captor = ArgumentCaptor.forClass(InvoiceNumberReservation.class);
+        verify(repository).save(captor.capture());
+        InvoiceNumberReservation saved = captor.getValue();
+        assertThat(saved.getStatus()).isEqualTo(InvoiceNumberReservationStatus.USED);
+        assertThat(saved.getNumber()).isEqualTo("RE-2024-0007");
+        assertThat(saved.getSequence()).isEqualTo(7L);
+        assertThat(saved.getReservedBy()).contains("bootstrap");
+    }
+
+    @Test
+    void markUsedSwallowsRepositoryFailures() {
+        when(repository.findByUserIdAndNumber(any(), any())).thenThrow(new RuntimeException("Mongo down"));
+        // Erwartung: keine Exception nach außen — Festschreiben darf an Audit nicht scheitern.
+        service.markUsed(invoice("R-2026-1", "i-1"));
+    }
+
+    @Test
+    void markUsedIgnoresInvoiceWithoutNumberOrUserId() {
+        CustomerInvoice missingNumber = new CustomerInvoice();
+        missingNumber.setUserId(userId.toHexString());
+        service.markUsed(missingNumber);
+
+        CustomerInvoice missingUser = new CustomerInvoice();
+        missingUser.setInvoiceNumber("R-1");
+        service.markUsed(missingUser);
+
+        verify(repository, never()).findByUserIdAndNumber(any(), any());
+        verify(repository, never()).save(any());
+    }
+
+    @Test
+    void markVoidedRequiresReason() {
+        assertThatThrownBy(() -> service.markVoided(userId, "R-1", "  "))
+                .isInstanceOf(IllegalArgumentException.class)
+                .hasMessageContaining("Grund");
+        assertThatThrownBy(() -> service.markVoided(userId, "R-1", null))
+                .isInstanceOf(IllegalArgumentException.class);
+    }
+
+    @Test
+    void markVoidedTransitionsReservedToVoided() {
+        InvoiceNumberReservation reservation = reservation("R-2026-000005", 5L,
+                InvoiceNumberReservationStatus.RESERVED);
+        when(repository.findByUserIdAndNumber(userId, "R-2026-000005")).thenReturn(Optional.of(reservation));
+        when(repository.save(any(InvoiceNumberReservation.class))).thenAnswer(inv -> inv.getArgument(0));
+
+        service.markVoided(userId, "R-2026-000005", "Versehentlich vergeben, Kunde widerrufen");
+
+        ArgumentCaptor<InvoiceNumberReservation> captor = ArgumentCaptor.forClass(InvoiceNumberReservation.class);
+        verify(repository).save(captor.capture());
+        InvoiceNumberReservation saved = captor.getValue();
+        assertThat(saved.getStatus()).isEqualTo(InvoiceNumberReservationStatus.VOIDED);
+        assertThat(saved.getVoidReason()).isEqualTo("Versehentlich vergeben, Kunde widerrufen");
+        assertThat(saved.getVoidedAt()).isNotNull();
+    }
+
+    @Test
+    void markVoidedRefusesToOverwriteUsedReservation() {
+        InvoiceNumberReservation reservation = reservation("R-2026-000005", 5L,
+                InvoiceNumberReservationStatus.USED);
+        when(repository.findByUserIdAndNumber(userId, "R-2026-000005")).thenReturn(Optional.of(reservation));
+
+        assertThatThrownBy(() -> service.markVoided(userId, "R-2026-000005", "Test"))
+                .isInstanceOf(InvoiceLifecycleException.class)
+                .hasMessageContaining("ausgestellten Rechnung");
+    }
+
+    @Test
+    void markVoidedFailsWhenNoReservationFound() {
+        when(repository.findByUserIdAndNumber(userId, "R-NOPE")).thenReturn(Optional.empty());
+
+        assertThatThrownBy(() -> service.markVoided(userId, "R-NOPE", "irrelevant"))
+                .isInstanceOf(InvoiceLifecycleException.class)
+                .hasMessageContaining("Keine Reservierung");
+    }
+
+    @Test
+    void findUnusedReturnsOnlyReservedAndVoided() {
+        when(repository.findByUserIdOrderBySequenceAsc(userId)).thenReturn(List.of(
+                reservation("R-1", 1L, InvoiceNumberReservationStatus.USED),
+                reservation("R-2", 2L, InvoiceNumberReservationStatus.RESERVED),
+                reservation("R-3", 3L, InvoiceNumberReservationStatus.USED),
+                reservation("R-4", 4L, InvoiceNumberReservationStatus.VOIDED)));
+
+        List<InvoiceNumberReservation> unused = service.findUnused(userId);
+
+        assertThat(unused).extracting(InvoiceNumberReservation::getNumber).containsExactly("R-2", "R-4");
+    }
+
+    private CustomerInvoice invoice(String number, String invoiceId) {
+        CustomerInvoice invoice = new CustomerInvoice();
+        invoice.setId(invoiceId);
+        invoice.setInvoiceNumber(number);
+        invoice.setUserId(userId.toHexString());
+        return invoice;
+    }
+
+    private InvoiceNumberReservation reservation(String number, long sequence,
+            InvoiceNumberReservationStatus status) {
+        InvoiceNumberReservation reservation = new InvoiceNumberReservation();
+        reservation.setUserId(userId);
+        reservation.setNumber(number);
+        reservation.setSequence(sequence);
+        reservation.setStatus(status);
+        return reservation;
+    }
+}