fix(pdf): align active entries periods and balances across exports (U03)

docs/usability-umsetzung.md

@@ -0,0 +1,29 @@
+# Umsetzung U01–U07
+
+Reihenfolge und je ein eigener Commit:
+
+1. **U01:** Gemeinsamer Datenpfad, SQLite-Online-Sicherung, geprüfte Wiederherstellung mit Rückfallsicherung und koordinierten Schreibzugriffen. Nur isolierte Testdaten wiederherstellen.
+2. **U02:** Strukturierte Ergebnisse (Erfolg, Abbruch, Fehler), sichtbare Meldungen, sichere Dateiaktionen und Sperre während Dateioperationen.
+3. **U03:** Nur wirksame Buchungen exportieren; Zeitraum, Anfangs-/Endstand und interne Umbuchungen erklären. PDF-Inhalte und Darstellung prüfen.
+4. **U04:** Gemeinsamer Jahreskontext, sichtbarer Zeitraum, Hinweis und Rückweg bei abweichendem Buchungsjahr; Datum beibehalten.
+5. **U05:** Alltagssprache, flexible Aktionsleiste, Wiederherstellung unter weiteren Aktionen, Hinweis zur Umbuchung.
+6. **U06:** Konto und Art anzeigen, feldnahe Validierung. Komma oder Punkt als Dezimaltrenner, keine Tausendertrenner; höchstens zwei Nachkommastellen, positive Beträge. Art beim Bearbeiten fest: falsche Buchung löschen und neu erfassen.
+7. **U07:** Speichersperre, Fortschritt, Fehler mit erhaltenen Eingaben, ausdrückliche Erfolgsmeldung und Hervorhebung.
+
+Prüfung: gezielte automatisierte Regressionen, Debug/Release, Desktop-Prüfung und PDF-Sichtprüfung soweit verfügbar. Anschließend Commits pushen und PR-Beschreibung mit Ergebnissen und Grenzen aktualisieren. U08–U16 bleiben außerhalb dieses Auftrags.
+
+## U01 – Sicherungsumfang
+
+Die Sicherung enthält Konten, Anfangsbestände, Buchungen einschließlich gelöschter Zeilen, Umbuchungsverknüpfungen und Datenbankschema. Vereinsname, Farbdarstellung und Fenstergröße liegen außerhalb der Datenbank und sind **nicht enthalten**. Eine Kopie auf derselben Festplatte schützt nicht gegen Geräteausfall; dafür die Sicherung zusätzlich auf einem unabhängigen Datenträger aufbewahren.
+
+Wiederherstellen akzeptiert nur vollständige Datenbanken derselben Schemaversion. Vorher wird die ausgewählte Datei als konsistenter SQLite-Snapshot zwischengespeichert und auf Integrität, Fremdschlüssel, Migrationen und alle Modellspalten geprüft. Die bestehende Datenbank erhält eine eindeutige `.before-restore-…bak` daneben. Diese Rückfallsicherungen werden nicht automatisch gelöscht; nach geprüfter Wiederherstellung bewusst archivieren. Anwendungsschreibzugriffe warten während der Wiederherstellung, SQLite koordiniert offene Leser. Der Austausch erfolgt mit der SQLite-Backup-API im bestehenden Datenbankhandle. Keine automatische Sicherung beim Beenden.
+
+Prüfung U01: 16/16 Debug-Tests bestanden, darunter WAL-Rundlauf mit exaktem Buchungsstand und Rückfallsicherung, beschädigte/fremde SQLite-Datei und fehlende Quelle. Kein echter Vereinsdatenbestand wurde zurückgespielt.
+
+## U02 – Dateiaktionen
+
+Strukturierte Ergebnisse und gemeinsame Statusanzeige mit optionalen technischen Details, Speicherpfad und „Ordner öffnen“. Abbruch ist neutral. Dateiaktionen sperren erneutes Auslösen; Fehler beim Erzeugen oder Öffnen einer PDF bleiben in der aktuellen Ansicht sichtbar. Native Dateidialoge melden Start-/Prozessfehler und erhalten Unicode-Pfade. Gespeichert wird über eine temporäre Datei, damit Schreibfehler eine bestehende Datei nicht verstümmeln. Prüfung: 18/18 Debug-Tests bestanden.
+
+## U03 – Gleiche Bedeutung in PDF und Oberfläche
+
+Einzelkonto und Übersicht enthalten nur wirksame Buchungen. Zeitraum und Bedeutung des Endstands sind ausdrücklich benannt, auch bei „Alle Jahre“ mit Anfangsbestand. Im Einzelkonto zählen Umbuchungen als Zu-/Abgang; die Übersicht zeigt beide Konten in einer Zeile und erklärt die unveränderte Vereinssumme. Prüfung: 19/19 Debug-Tests. PDF-Textextraktion prüft 58,30 € Kontostand, 108,30 € Vereinssumme, ausgeschlossene gelöschte/spätere Buchungen und Richtung. Einzelkonto, gemeinsame Übersicht und Seiten 2/3 eines dreiseitigen Auszugs gerendert und visuell auf Lesbarkeit, wiederholte Kopfzeilen und Abschluss geprüft.

src/Duempelkas.App/Components/OperationNotice.razor

@@ -0,0 +1,40 @@
+@inject IFileSaveService FileSaveService
+
+@if (Result != null)
+{
+    <div class="alert @(Result.Status == FileOperationStatus.Error ? "alert-danger" : Result.Status == FileOperationStatus.Success ? "alert-success" : "alert-info")" role="status" aria-live="polite" aria-atomic="true">
+        <p>@Result.Message</p>
+        @if (Result.Path != null)
+        {
+            <p class="text-break">@Result.Path</p>
+            <button class="btn btn-outline-secondary" disabled="@busy" @onclick="OpenFolder">Ordner öffnen</button>
+        }
+        @if (Result.Details != null)
+        {
+            <details><summary>Technische Details</summary><p class="text-break">@Result.Details</p></details>
+        }
+        @if (openResult != null)
+        {
+            <p role="alert">@openResult.Message</p>
+            @if (openResult.Details != null) { <details><summary>Technische Details</summary>@openResult.Details</details> }
+        }
+    </div>
+}
+
+@code {
+    [Parameter] public FileOperationResult? Result { get; set; }
+    private FileOperationResult? openResult;
+    private FileOperationResult? previous;
+    private bool busy;
+    protected override void OnParametersSet()
+    {
+        if (previous != Result) { openResult = null; previous = Result; }
+    }
+    private async Task OpenFolder()
+    {
+        if (busy || Result?.Path == null) return;
+        busy = true;
+        try { openResult = await FileSaveService.OpenFolderAsync(Result.Path); }
+        finally { busy = false; }
+    }
+}

src/Duempelkas.App/Pages/Accounts/AccountDetail.razor

@@ -7,6 +7,9 @@
 @inject NavigationManager Navigation
 
 <div class="container-fluid">
+    <OperationNotice Result="fileResult" />
+    @if (fileBusy) { <p role="status" aria-live="polite">Dateiaktion läuft … Bitte warten.</p> }
+
     @if (account == null)
     {
         <div class="text-center py-5">
@@ -35,7 +38,7 @@
             <button class="btn btn-info btn-nav" @onclick="() => showAddTransfer = true">
                 <i class="bi bi-arrow-left-right"></i> Umbuchung
             </button>
-            <button class="btn btn-dark btn-nav" @onclick="HandleExport">
+            <button class="btn btn-dark btn-nav" @onclick="HandleExport" disabled="@fileBusy">
                 <i class="bi bi-file-earmark-pdf"></i> PDF
             </button>
             |

src/Duempelkas.App/Pages/Accounts/AccountDetail.razor.cs

@@ -32,6 +32,8 @@ public partial class AccountDetail
     private string? confirmRestoreEntryTitle;
 
     private string? savedPdfPath;
+    private FileOperationResult? fileResult;
+    private bool fileBusy;
 
     private EntryDto? editingEntry;
     private EntryDto? editingTransferEntry;
@@ -178,19 +180,39 @@ public partial class AccountDetail
 
     private async Task HandleExport()
     {
+        if (fileBusy) return;
+        fileBusy = true;
+        fileResult = null;
+        try
+        {
         var pdf = await PdfStatementService.GenerateStatementAsync(AccountId, selectedYear);
         var suffix = selectedYear.HasValue ? $"_{selectedYear.Value}" : "_Gesamt";
-        savedPdfPath = await FileSaveService.SaveFileAsync(pdf, $"{account?.Name}{suffix}.pdf");
+        fileResult = await FileSaveService.SaveFileAsync(pdf, $"{account?.Name}{suffix}.pdf");
+
+            savedPdfPath = fileResult.Status == FileOperationStatus.Success ? fileResult.Path : null;
+
+        }
+        catch (Exception ex) { fileResult = FileOperationResult.Error(ex); }
+        finally { fileBusy = false; }
     }
 
     private async Task HandleOpenSavedPdf()
     {
+        if (fileBusy) return;
+        fileBusy = true;
+        fileResult = null;
+        try
+        {
         if (!string.IsNullOrWhiteSpace(savedPdfPath))
         {
-            await FileSaveService.OpenFileAsync(savedPdfPath);
+            fileResult = await FileSaveService.OpenFileAsync(savedPdfPath);
         }
 
         savedPdfPath = null;
+
+        }
+        catch (Exception ex) { fileResult = FileOperationResult.Error(ex); }
+        finally { fileBusy = false; }
     }
 
     private void CancelOpenSavedPdf()

src/Duempelkas.App/Pages/Dashboard.razor

@@ -8,6 +8,9 @@
 @inject NavigationManager NavigationManager
 
 <div class="container-fluid">
+    <OperationNotice Result="fileResult" />
+    @if (fileBusy) { <p role="status" aria-live="polite">Dateiaktion läuft … Bitte warten.</p> }
+
 
     <div class="d-flex justify-content-between align-items-center">
         <div class="d-flex align-items-center flex-grow-1" style="min-width: 0;">
@@ -25,14 +28,14 @@
             <i class="bi bi-plus-lg"></i> Neues Konto
         </button>
         |
-        <button class="btn-nav btn-success" @onclick="HandleBackupAsync">
+        <button class="btn-nav btn-success" @onclick="HandleBackupAsync" disabled="@fileBusy">
             <i class="bi bi-save"></i> Backup
         </button>
-        <button class="btn-nav btn-warning" @onclick="HandleRestoreAsync">
+        <button class="btn-nav btn-warning" @onclick="HandleRestoreAsync" disabled="@fileBusy">
             <i class="bi bi-arrow-counterclockwise"></i> Restore
         </button>
         |
-        <button class="btn-nav btn-dark" @onclick="HandleDashboardExportAsync">
+        <button class="btn-nav btn-dark" @onclick="HandleDashboardExportAsync" disabled="@fileBusy">
             <i class="bi bi-file-earmark-pdf"></i> PDF
         </button>
         |
@@ -54,12 +57,6 @@
         </div>
     }
 
-    @if (!string.IsNullOrWhiteSpace(operationMessage))
-    {
-        <div class="alert @operationMessageClass mb-3" role="alert">
-            @operationMessage
-        </div>
-    }
 
     @if (accounts == null)
     {

src/Duempelkas.App/Pages/Dashboard.razor.cs

@@ -17,9 +17,9 @@ public partial class Dashboard
     private int? selectedYear = DateTime.Now.Year;
     private List<int> availableYears = [];
     private string clubName = string.Empty;
-    private string? operationMessage;
-    private string operationMessageClass = "alert-info";
     private string? savedPdfPath;
+    private FileOperationResult? fileResult;
+    private bool fileBusy;
     private string currentTheme = "light";
 
     #endregion
@@ -100,11 +100,16 @@ public partial class Dashboard
 
     private async Task HandleBackupAsync()
     {
-        var message = await BackupService.CreateBackupAsync();
-        if (message.Contains("fehlgeschlagen", StringComparison.OrdinalIgnoreCase))
+        if (fileBusy) return;
+        fileBusy = true;
+        fileResult = null;
+        try
         {
-            SetOperationMessage(message, false);
+            fileResult = await BackupService.CreateBackupAsync();
+
         }
+        catch (Exception ex) { fileResult = FileOperationResult.Error(ex); }
+        finally { fileBusy = false; }
     }
 
     private Task HandleRestoreAsync()
@@ -120,25 +125,36 @@ public partial class Dashboard
 
     private async Task HandleConfirmRestore()
     {
-        showRestoreConfirm = false;
-        var message = await BackupService.RestoreBackupAsync();
-        var isSuccess = message.StartsWith("Wiederherstellung erfolgreich", StringComparison.OrdinalIgnoreCase);
+        if (fileBusy) return;
+        fileBusy = true;
+        fileResult = null;
+        try
+        {
+            showRestoreConfirm = false;
+            fileResult = await BackupService.RestoreBackupAsync();
+            if (fileResult.Status == FileOperationStatus.Success) await LoadAll();
 
-        if (isSuccess)
-        {
-            NavigationManager.NavigateTo("/", forceLoad: true);
-        }
-        else
-        {
-            SetOperationMessage(message, isSuccess);
         }
+        catch (Exception ex) { fileResult = FileOperationResult.Error(ex); }
+        finally { fileBusy = false; }
     }
 
     private async Task HandleDashboardExportAsync()
     {
+        if (fileBusy) return;
+        fileBusy = true;
+        fileResult = null;
+        try
+        {
         var pdf = await PdfStatementService.GenerateDashboardStatementAsync(selectedYear);
         var suffix = selectedYear.HasValue ? $"_{selectedYear.Value}" : "_Gesamt";
-        savedPdfPath = await FileSaveService.SaveFileAsync(pdf, $"{DisplayClubName}_Übersicht{suffix}.pdf");
+        fileResult = await FileSaveService.SaveFileAsync(pdf, $"{DisplayClubName}_Übersicht{suffix}.pdf");
+
+            savedPdfPath = fileResult.Status == FileOperationStatus.Success ? fileResult.Path : null;
+
+        }
+        catch (Exception ex) { fileResult = FileOperationResult.Error(ex); }
+        finally { fileBusy = false; }
     }
 
     private void OpenYearFilterDialog()
@@ -160,12 +176,21 @@ public partial class Dashboard
 
     private async Task HandleOpenSavedPdf()
     {
+        if (fileBusy) return;
+        fileBusy = true;
+        fileResult = null;
+        try
+        {
         if (!string.IsNullOrWhiteSpace(savedPdfPath))
         {
-            await FileSaveService.OpenFileAsync(savedPdfPath);
+            fileResult = await FileSaveService.OpenFileAsync(savedPdfPath);
         }
 
         savedPdfPath = null;
+
+        }
+        catch (Exception ex) { fileResult = FileOperationResult.Error(ex); }
+        finally { fileBusy = false; }
     }
 
     private void CancelOpenSavedPdf()
@@ -177,12 +202,6 @@ public partial class Dashboard
 
     #region Helpers
 
-    private void SetOperationMessage(string message, bool success)
-    {
-        operationMessage = message;
-        operationMessageClass = success ? "alert-success" : "alert-danger";
-    }
-
     private static string FormatCurrency(decimal amount)
     {
         return amount.ToString("N2", CultureInfo.GetCultureInfo("de-DE")) + " €";

src/Duempelkas.App/Services/IBackupService.cs

@@ -1,7 +1,9 @@
+using Duempelkas.App.Services.Models;
+
 namespace Duempelkas.App.Services;
 
 public interface IBackupService
 {
-    Task<string> CreateBackupAsync();
-    Task<string> RestoreBackupAsync();
+    Task<FileOperationResult> CreateBackupAsync();
+    Task<FileOperationResult> RestoreBackupAsync();
 }

src/Duempelkas.App/Services/IFileDialogService.cs

@@ -0,0 +1,7 @@
+namespace Duempelkas.App.Services;
+
+public interface IFileDialogService
+{
+    Task<string?> SaveAsync(string suggestedFileName);
+    Task<string?> OpenBackupAsync();
+}

src/Duempelkas.App/Services/IFileSaveService.cs

@@ -1,7 +1,10 @@
+using Duempelkas.App.Services.Models;
+
 namespace Duempelkas.App.Services;
 
 public interface IFileSaveService
 {
-    Task<string?> SaveFileAsync(byte[] content, string suggestedFileName);
-    Task OpenFileAsync(string filePath);
+    Task<FileOperationResult> SaveFileAsync(byte[] content, string suggestedFileName);
+    Task<FileOperationResult> OpenFileAsync(string filePath);
+    Task<FileOperationResult> OpenFolderAsync(string filePath);
 }

src/Duempelkas.App/Services/Models/FileOperationResult.cs

@@ -0,0 +1,10 @@
+namespace Duempelkas.App.Services.Models;
+
+public enum FileOperationStatus { Success, Cancelled, Error }
+
+public sealed record FileOperationResult(FileOperationStatus Status, string Message, string? Path = null, string? Details = null)
+{
+    public static FileOperationResult Cancelled() => new(FileOperationStatus.Cancelled, "Vorgang abgebrochen. Es wurde nichts geändert.");
+    public static FileOperationResult Error(Exception error) => new(FileOperationStatus.Error,
+        "Die Dateiaktion konnte nicht abgeschlossen werden. Bitte den Speicherort und die Zugriffsrechte prüfen oder einen anderen Speicherort wählen.", Details: error.Message);
+}

src/Duempelkas.Desktop/Program.cs

@@ -38,11 +38,15 @@ class Program
         {
             try
             {
-                File.Copy(legacyDbPath, dbPath);
+                using var source = new Microsoft.Data.Sqlite.SqliteConnection($"Data Source={legacyDbPath};Mode=ReadOnly");
+                using var target = new Microsoft.Data.Sqlite.SqliteConnection($"Data Source={dbPath}");
+                source.Open();
+                target.Open();
+                source.BackupDatabase(target);
             }
-            catch
+            catch (Exception ex)
             {
-                // Ignore copy errors and continue with a fresh DB.
+                throw new InvalidOperationException("Die vorhandene Datenbank konnte nicht ?bernommen werden. Der Start wurde abgebrochen; die urspr?ngliche Datei bleibt erhalten.", ex);
             }
         }
 

src/Duempelkas.Infrastructure/DependencyInjection.cs

@@ -10,6 +10,7 @@ public static class DependencyInjection
 {
     public static IServiceCollection AddInfrastructure(this IServiceCollection services, string connectionString)
     {
+        services.AddSingleton(new DatabaseLocation(connectionString));
         services.AddDbContext<FinanceDbContext>(options =>
             options.UseSqlite(connectionString));
         services.AddDbContextFactory<FinanceDbContext>(options =>
@@ -19,6 +20,7 @@ public static class DependencyInjection
         services.AddScoped<IEntryService, EntryService>();
         services.AddScoped<IBalanceQueryService, BalanceQueryService>();
         services.AddScoped<IPdfStatementService, PdfStatementService>();
+        services.AddSingleton<IFileDialogService, FileDialogService>();
         services.AddScoped<IFileSaveService, FileSaveService>();
         services.AddSingleton<IBackupService, BackupService>();
         services.AddSingleton<ISettingsService, SettingsService>();

src/Duempelkas.Infrastructure/Services/AccountService.cs

@@ -11,7 +11,13 @@ public class AccountService : IAccountService
 {
     private readonly IDbContextFactory<FinanceDbContext> _dbFactory;
 
-    public AccountService(IDbContextFactory<FinanceDbContext> dbFactory) => _dbFactory = dbFactory;
+    private readonly DatabaseLocation? _location;
+
+    public AccountService(IDbContextFactory<FinanceDbContext> dbFactory, DatabaseLocation? location = null)
+    {
+        _dbFactory = dbFactory;
+        _location = location;
+    }
 
     public Task<List<AccountSummaryDto>> GetAllAccountsAsync()
     {
@@ -20,6 +26,7 @@ public class AccountService : IAccountService
 
     public async Task<List<AccountSummaryDto>> GetAllAccountsAsync(int? year)
     {
+        using var lease = await DatabaseLease.AcquireAsync(_location);
         await using var db = await _dbFactory.CreateDbContextAsync();
 
         var accounts = await db.Accounts
@@ -71,6 +78,7 @@ public class AccountService : IAccountService
 
     public async Task<AccountSummaryDto> GetAccountAsync(int accountId)
     {
+        using var lease = await DatabaseLease.AcquireAsync(_location);
         await using var db = await _dbFactory.CreateDbContextAsync();
 
         var account = await db.Accounts
@@ -87,6 +95,7 @@ public class AccountService : IAccountService
 
     public async Task<AccountSummaryDto> CreateAccountAsync(string name)
     {
+        using var lease = await DatabaseLease.AcquireAsync(_location);
         await using var db = await _dbFactory.CreateDbContextAsync();
 
         var account = new Account { Name = name };
@@ -97,6 +106,7 @@ public class AccountService : IAccountService
 
     public async Task RenameAccountAsync(int accountId, string newName)
     {
+        using var lease = await DatabaseLease.AcquireAsync(_location);
         await using var db = await _dbFactory.CreateDbContextAsync();
 
         var account = await db.Accounts.FindAsync(accountId)
@@ -107,6 +117,7 @@ public class AccountService : IAccountService
 
     public async Task UpdateCarryoverAsync(int accountId, decimal carryoverBalance)
     {
+        using var lease = await DatabaseLease.AcquireAsync(_location);
         await using var db = await _dbFactory.CreateDbContextAsync();
 
         var account = await db.Accounts.FindAsync(accountId)
@@ -123,6 +134,7 @@ public class AccountService : IAccountService
             return;
         }
 
+        using var lease = await DatabaseLease.AcquireAsync(_location);
         await using var db = await _dbFactory.CreateDbContextAsync();
 
         var account = await db.Accounts.FindAsync(accountId)
@@ -138,6 +150,7 @@ public class AccountService : IAccountService
 
     public async Task DeleteAccountAsync(int accountId)
     {
+        using var lease = await DatabaseLease.AcquireAsync(_location);
         await using var db = await _dbFactory.CreateDbContextAsync();
 
         var account = await db.Accounts

src/Duempelkas.Infrastructure/Services/BackupService.cs

@@ -1,3 +1,4 @@
+using Duempelkas.App.Services.Models;
 using System.Diagnostics;
 using System.Runtime.InteropServices;
 using Duempelkas.App.Services;
@@ -7,140 +8,126 @@ namespace Duempelkas.Infrastructure.Services;
 
 public class BackupService : IBackupService
 {
-    private static readonly string DbPath = Path.Combine(
-        Path.GetDirectoryName(Environment.ProcessPath ?? AppContext.BaseDirectory) ?? AppContext.BaseDirectory,
-        "duempelkas.db");
+    private readonly DatabaseLocation location;
 
-    public async Task<string> CreateBackupAsync()
+    private readonly IFileDialogService dialogs;
+    public BackupService(DatabaseLocation location, IFileDialogService? dialogs = null)
     {
-        if (!File.Exists(DbPath))
-        {
-            return "Keine Datenbankdatei gefunden.";
-        }
-
-        var suggestedFileName = $"duempelkas-backup-{DateTime.Now:yyMMdd-HHmm}.bak";
-        var backupPath = await ShowSaveDialogAsync(suggestedFileName);
-
-        if (string.IsNullOrWhiteSpace(backupPath))
-        {
-            return "Backup wurde abgebrochen.";
-        }
-
-        backupPath = Path.ChangeExtension(backupPath, ".bak");
-
-        try
-        {
-            File.Copy(DbPath, backupPath, overwrite: true);
-            return $"Backup gespeichert: {backupPath}";
-        }
-        catch (Exception ex)
-        {
-            return $"Backup fehlgeschlagen: {ex.Message}";
-        }
+        this.location = location;
+        this.dialogs = dialogs ?? new FileDialogService();
     }
 
-    public async Task<string> RestoreBackupAsync()
+    public async Task<FileOperationResult> CreateBackupAsync()
     {
-        var backupPath = await ShowOpenDialogAsync();
-        if (string.IsNullOrWhiteSpace(backupPath))
-        {
-            return "Wiederherstellung wurde abgebrochen.";
-        }
-
-        if (!File.Exists(backupPath))
-        {
-            return "Die gewählte Backup-Datei wurde nicht gefunden.";
-        }
-
         try
         {
-            // Ensure no pooled connection keeps stale handles to the previous DB file.
-            SqliteConnection.ClearAllPools();
-
-            var targetDirectory = Path.GetDirectoryName(DbPath);
-            if (!string.IsNullOrWhiteSpace(targetDirectory))
-            {
-                Directory.CreateDirectory(targetDirectory);
-            }
-
-            File.Copy(backupPath, DbPath, overwrite: true);
-            SqliteConnection.ClearAllPools();
-            return "Wiederherstellung erfolgreich. Die Datenbank wurde neu geladen.";
-        }
-        catch (Exception ex)
-        {
-            return $"Wiederherstellung fehlgeschlagen: {ex.Message}";
+            var path = await dialogs.SaveAsync($"duempelkas-backup-{DateTime.Now:yyyyMMdd-HHmmss}.bak");
+            if (string.IsNullOrWhiteSpace(path)) return FileOperationResult.Cancelled();
+            await CreateBackupToAsync(path);
+            return new(FileOperationStatus.Success, "Sicherung gespeichert.", path);
         }
+        catch (Exception ex) { return FileOperationResult.Error(ex); }
     }
 
-    private static Task<string?> ShowSaveDialogAsync(string suggestedFileName)
+    public async Task<FileOperationResult> RestoreBackupAsync()
     {
-        return Task.Run(() =>
+        try
         {
-            if (!RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            var path = await dialogs.OpenBackupAsync();
+            if (string.IsNullOrWhiteSpace(path)) return FileOperationResult.Cancelled();
+            var fallback = await RestoreFromAsync(path);
+            return new(FileOperationStatus.Success, "Sicherung zurückgespielt. Die bisherigen Daten liegen in der Rückfallsicherung:", fallback);
+        }
+        catch (Exception ex) { return FileOperationResult.Error(ex); }
+    }
+
+    public async Task CreateBackupToAsync(string path)
+    {
+        using var lease = await DatabaseLease.AcquireAsync(location);
+        RejectActivePath(path);
+        await Task.Run(() =>
+        {
+            var staged = System.IO.Path.GetFullPath(path) + $".{Guid.NewGuid():N}.tmp";
+            try
             {
-                var documentsPath = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
-                return Path.Combine(documentsPath, suggestedFileName);
+                Snapshot(location.Path, staged);
+                File.Move(staged, path, overwrite: true);
             }
-
-            var script = $@"
-Add-Type -AssemblyName System.Windows.Forms
-$dialog = New-Object System.Windows.Forms.SaveFileDialog
-$dialog.Filter = 'Backup-Dateien (*.bak)|*.bak'
-$dialog.DefaultExt = 'bak'
-$dialog.AddExtension = $true
-$dialog.OverwritePrompt = $true
-$dialog.FileName = '{suggestedFileName.Replace("'", "''")}'
-$dialog.Title = 'Backup speichern'
-if ($dialog.ShowDialog() -eq 'OK') {{ $dialog.FileName }} else {{ '' }}
-";
-
-            return RunPowerShellDialog(script);
+            finally { if (File.Exists(staged)) File.Delete(staged); }
         });
     }
 
-    private static Task<string?> ShowOpenDialogAsync()
+    public async Task<string> RestoreFromAsync(string path)
     {
-        return Task.Run(() =>
+        using var lease = await DatabaseLease.AcquireAsync(location);
+        return await Task.Run(() =>
         {
-            if (!RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            RejectActivePath(path);
+            // Stage the selected database first, so a changing/removable source cannot
+            // change between validation and restore. BackupDatabase includes WAL data.
+            var staged = System.IO.Path.Combine(System.IO.Path.GetTempPath(), $"duempelkas-{Guid.NewGuid():N}.db");
+            try
             {
-                return null;
+                Snapshot(path, staged);
+                Validate(staged);
+                var fallback = location.Path + $".before-restore-{DateTime.Now:yyyyMMdd-HHmmss}-{Guid.NewGuid():N}.bak";
+                Snapshot(location.Path, fallback);
+                // SQLite's online backup atomically replaces database contents, retaining
+                // the active file/handles and coordinating locks. Never copy over an open DB.
+                Snapshot(staged, location.Path);
+                return fallback;
             }
-
-            var script = @"
-Add-Type -AssemblyName System.Windows.Forms
-$dialog = New-Object System.Windows.Forms.OpenFileDialog
-$dialog.Filter = 'Backup-Dateien (*.bak)|*.bak'
-$dialog.Multiselect = $false
-$dialog.Title = 'Backup auswählen'
-if ($dialog.ShowDialog() -eq 'OK') { $dialog.FileName } else { '' }
-";
-
-            return RunPowerShellDialog(script);
+            finally { if (File.Exists(staged)) File.Delete(staged); }
         });
     }
 
-    private static string? RunPowerShellDialog(string script)
+    private void RejectActivePath(string path)
     {
-        var psi = new ProcessStartInfo
-        {
-            FileName = "powershell",
-            Arguments = $"-NoProfile -Command \"{script.Replace("\"", "\\\"") }\"",
-            RedirectStandardOutput = true,
-            UseShellExecute = false,
-            CreateNoWindow = true
-        };
-
-        using var process = Process.Start(psi);
-        if (process == null)
-        {
-            return null;
-        }
-
-        var result = process.StandardOutput.ReadToEnd().Trim();
-        process.WaitForExit();
-
-        return string.IsNullOrWhiteSpace(result) ? null : result;
+        if (new[] { location.Path, location.Path + "-wal", location.Path + "-shm", location.Path + "-journal" }
+            .Contains(System.IO.Path.GetFullPath(path), StringComparer.OrdinalIgnoreCase))
+            throw new InvalidOperationException("Bitte eine andere Datei als die aktive Datenbank wählen.");
     }
-}
+
+    private static SqliteConnection Open(string path, SqliteOpenMode mode)
+    {
+        var connection = new SqliteConnection(new SqliteConnectionStringBuilder
+        {
+            DataSource = System.IO.Path.GetFullPath(path), Mode = mode, Pooling = false
+        }.ToString());
+        try { connection.Open(); return connection; }
+        catch { connection.Dispose(); throw; }
+    }
+
+    private static void Snapshot(string source, string destination)
+    {
+        if (string.Equals(System.IO.Path.GetFullPath(source), System.IO.Path.GetFullPath(destination), StringComparison.OrdinalIgnoreCase))
+            throw new InvalidOperationException("Quelle und Ziel müssen verschiedene Dateien sein.");
+        using var input = Open(source, SqliteOpenMode.ReadOnly);
+        using var output = Open(destination, SqliteOpenMode.ReadWriteCreate);
+        input.BackupDatabase(output);
+    }
+
+    private static void Validate(string path)
+    {
+        using var connection = Open(path, SqliteOpenMode.ReadOnly);
+        using var check = connection.CreateCommand();
+        check.CommandText = "PRAGMA integrity_check";
+        if (!string.Equals(check.ExecuteScalar()?.ToString(), "ok", StringComparison.Ordinal))
+            throw new InvalidOperationException("Die Sicherung ist beschädigt.");
+        check.CommandText = "PRAGMA foreign_key_check";
+        using (var reader = check.ExecuteReader())
+            if (reader.Read()) throw new InvalidOperationException("Die Sicherung enthält ungültige Verknüpfungen.");
+        var options = new Microsoft.EntityFrameworkCore.DbContextOptionsBuilder<Duempelkas.Infrastructure.Persistence.FinanceDbContext>();
+        Microsoft.EntityFrameworkCore.SqliteDbContextOptionsBuilderExtensions.UseSqlite(options, connection);
+        using var db = new Duempelkas.Infrastructure.Persistence.FinanceDbContext(options.Options);
+        var expected = Microsoft.EntityFrameworkCore.RelationalDatabaseFacadeExtensions.GetMigrations(db.Database).ToArray();
+        var applied = Microsoft.EntityFrameworkCore.RelationalDatabaseFacadeExtensions.GetAppliedMigrations(db.Database).ToArray();
+        if (!expected.SequenceEqual(applied))
+            throw new InvalidOperationException("Diese Sicherung passt nicht zu dieser Programmversion.");
+        // Materialize every mapped column to reject a forged/missing schema before touching active data.
+        _ = db.Accounts.ToArray();
+        _ = db.Entries.ToArray();
+        _ = db.TransferLinks.ToArray();
+    }
+
+}

src/Duempelkas.Infrastructure/Services/DatabaseLease.cs

@@ -0,0 +1,12 @@
+namespace Duempelkas.Infrastructure.Services;
+
+internal sealed class DatabaseLease(SemaphoreSlim? gate) : IDisposable
+{
+    public static async Task<DatabaseLease> AcquireAsync(DatabaseLocation? location)
+    {
+        if (location != null) await location.Writes.WaitAsync();
+        return new DatabaseLease(location?.Writes);
+    }
+
+    public void Dispose() => gate?.Release();
+}

src/Duempelkas.Infrastructure/Services/DatabaseLocation.cs

@@ -0,0 +1,12 @@
+using Microsoft.Data.Sqlite;
+
+namespace Duempelkas.Infrastructure.Services;
+
+public sealed class DatabaseLocation(string connectionString)
+{
+    public string Path { get; } = System.IO.Path.GetFullPath(new SqliteConnectionStringBuilder(connectionString).DataSource);
+    public string ConnectionString { get; } = connectionString;
+    // All application mutations and restore share this gate. SQLite's backup API
+    // also coordinates readers and external connections through SQLite locks.
+    public SemaphoreSlim Writes { get; } = new(1, 1);
+}

src/Duempelkas.Infrastructure/Services/EntryService.cs

@@ -11,7 +11,13 @@ public class EntryService : IEntryService
 {
     private readonly IDbContextFactory<FinanceDbContext> _dbFactory;
 
-    public EntryService(IDbContextFactory<FinanceDbContext> dbFactory) => _dbFactory = dbFactory;
+    private readonly DatabaseLocation? _location;
+
+    public EntryService(IDbContextFactory<FinanceDbContext> dbFactory, DatabaseLocation? location = null)
+    {
+        _dbFactory = dbFactory;
+        _location = location;
+    }
 
     public Task<List<EntryDto>> GetEntriesAsync(int accountId, bool currentYearOnly)
     {
@@ -21,6 +27,7 @@ public class EntryService : IEntryService
 
     public async Task<List<EntryDto>> GetEntriesAsync(int accountId, int? year)
     {
+        using var lease = await DatabaseLease.AcquireAsync(_location);
         await using var db = await _dbFactory.CreateDbContextAsync();
 
         var query = db.Entries.Where(e => e.AccountId == accountId);
@@ -67,6 +74,7 @@ public class EntryService : IEntryService
 
     public async Task<List<int>> GetEntryYearsAsync(int accountId)
     {
+        using var lease = await DatabaseLease.AcquireAsync(_location);
         await using var db = await _dbFactory.CreateDbContextAsync();
 
         return await db.Entries
@@ -79,6 +87,7 @@ public class EntryService : IEntryService
 
     public async Task<List<int>> GetAllEntryYearsAsync()
     {
+        using var lease = await DatabaseLease.AcquireAsync(_location);
         await using var db = await _dbFactory.CreateDbContextAsync();
 
         return await db.Entries
@@ -90,6 +99,7 @@ public class EntryService : IEntryService
 
     public async Task<EntryDto> CreateEntryAsync(int accountId, EntryType type, DateTime date, string title, decimal amount)
     {
+        using var lease = await DatabaseLease.AcquireAsync(_location);
         await using var db = await _dbFactory.CreateDbContextAsync();
 
         var displayId = await GenerateDisplayIdAsync(db, date.Year);
@@ -114,6 +124,7 @@ public class EntryService : IEntryService
         if (sourceAccountId == targetAccountId)
             throw new InvalidOperationException("Umbuchung innerhalb desselben Kontos ist nicht möglich.");
 
+        using var lease = await DatabaseLease.AcquireAsync(_location);
         await using var db = await _dbFactory.CreateDbContextAsync();
         await using var transaction = await db.Database.BeginTransactionAsync();
 
@@ -163,6 +174,7 @@ public class EntryService : IEntryService
 
     public async Task DeleteEntryAsync(int entryId)
     {
+        using var lease = await DatabaseLease.AcquireAsync(_location);
         await using var db = await _dbFactory.CreateDbContextAsync();
 
         var entry = await db.Entries.FindAsync(entryId)
@@ -185,6 +197,7 @@ public class EntryService : IEntryService
 
     public async Task RestoreEntryAsync(int entryId)
     {
+        using var lease = await DatabaseLease.AcquireAsync(_location);
         await using var db = await _dbFactory.CreateDbContextAsync();
 
         var entry = await db.Entries.FindAsync(entryId)
@@ -207,6 +220,7 @@ public class EntryService : IEntryService
 
     public async Task UpdateEntryAsync(int entryId, DateTime date, string title, decimal amount)
     {
+        using var lease = await DatabaseLease.AcquireAsync(_location);
         await using var db = await _dbFactory.CreateDbContextAsync();
 
         var entry = await db.Entries.FindAsync(entryId)
@@ -236,6 +250,7 @@ public class EntryService : IEntryService
 
     public async Task UpdateTransferAsync(int entryId, int newLinkedAccountId, DateTime date, string title, decimal amount)
     {
+        using var lease = await DatabaseLease.AcquireAsync(_location);
         await using var db = await _dbFactory.CreateDbContextAsync();
 
         var entry = await db.Entries.FindAsync(entryId)

src/Duempelkas.Infrastructure/Services/FileDialogService.cs

@@ -0,0 +1,44 @@
+using System.Diagnostics;
+using System.Text;
+using Duempelkas.App.Services;
+
+namespace Duempelkas.Infrastructure.Services;
+
+public sealed class FileDialogService : IFileDialogService
+{
+    public Task<string?> SaveAsync(string suggestedFileName) => ShowAsync(suggestedFileName);
+    public Task<string?> OpenBackupAsync() => ShowAsync(null);
+
+    private static Task<string?> ShowAsync(string? suggestedFileName) => Task.Run(() =>
+    {
+        if (!OperatingSystem.IsWindows())
+            throw new PlatformNotSupportedException("Der Dateidialog ist auf diesem System nicht verfügbar.");
+        var save = suggestedFileName != null;
+        var extension = save ? (Path.GetExtension(suggestedFileName) ?? "") : ".bak";
+        var script = $$"""
+            $ErrorActionPreference = 'Stop'
+            [Console]::OutputEncoding = [System.Text.UTF8Encoding]::new($false)
+            Add-Type -AssemblyName System.Windows.Forms
+            $dialog = New-Object System.Windows.Forms.{{(save ? "SaveFileDialog" : "OpenFileDialog")}}
+            $dialog.Filter = 'Dateien (*{{extension.Replace("'", "''")}})|*{{extension.Replace("'", "''")}}'
+            $dialog.Title = '{{(save ? "Datei speichern" : "Sicherung auswählen")}}'
+            {{(save ? "$dialog.OverwritePrompt = $true\n$dialog.AddExtension = $true\n$dialog.DefaultExt = '" + extension.TrimStart('.').Replace("'", "''") + "'\n$dialog.FileName = '" + suggestedFileName!.Replace("'", "''") + "'" : "$dialog.Multiselect = $false")}}
+            try { if ($dialog.ShowDialog() -eq 'OK') { [Console]::Write($dialog.FileName) } } finally { $dialog.Dispose() }
+            """;
+        var start = new ProcessStartInfo("powershell.exe")
+        {
+            RedirectStandardOutput = true, RedirectStandardError = true,
+            StandardOutputEncoding = Encoding.UTF8, UseShellExecute = false, CreateNoWindow = true
+        };
+        start.ArgumentList.Add("-NoProfile");
+        start.ArgumentList.Add("-STA");
+        start.ArgumentList.Add("-EncodedCommand");
+        start.ArgumentList.Add(Convert.ToBase64String(Encoding.Unicode.GetBytes(script)));
+        using var process = Process.Start(start) ?? throw new IOException("Der Dateidialog konnte nicht gestartet werden.");
+        var output = process.StandardOutput.ReadToEnd();
+        var error = process.StandardError.ReadToEnd();
+        process.WaitForExit();
+        if (process.ExitCode != 0) throw new IOException("Der Dateidialog konnte nicht geöffnet werden. " + error);
+        return string.IsNullOrWhiteSpace(output) ? null : output;
+    });
+}

src/Duempelkas.Infrastructure/Services/FileSaveService.cs

@@ -1,90 +1,49 @@
+using Duempelkas.App.Services.Models;
 using System.Diagnostics;
 using System.Runtime.InteropServices;
 using Duempelkas.App.Services;
 
 namespace Duempelkas.Infrastructure.Services;
 
-public class FileSaveService : IFileSaveService
+public class FileSaveService(IFileDialogService dialogs) : IFileSaveService
 {
-    public async Task<string?> SaveFileAsync(byte[] content, string suggestedFileName)
+    public async Task<FileOperationResult> SaveFileAsync(byte[] content, string suggestedFileName)
     {
-        var filePath = await ShowSaveDialogAsync(suggestedFileName);
-        if (filePath == null) return null;
-
-        await File.WriteAllBytesAsync(filePath, content);
-        return filePath;
-    }
-
-    public Task OpenFileAsync(string filePath)
-    {
-        if (string.IsNullOrWhiteSpace(filePath) || !File.Exists(filePath))
+        string? staged = null;
+        try
         {
-            return Task.CompletedTask;
+            var path = await dialogs.SaveAsync(suggestedFileName);
+            if (string.IsNullOrWhiteSpace(path)) return FileOperationResult.Cancelled();
+            staged = path + $".{Guid.NewGuid():N}.tmp";
+            await File.WriteAllBytesAsync(staged, content);
+            File.Move(staged, path, overwrite: true);
+            return new(FileOperationStatus.Success, "Datei gespeichert.", path);
         }
-
-        return Task.Run(() =>
-        {
-            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
-            {
-                Process.Start(new ProcessStartInfo
-                {
-                    FileName = filePath,
-                    UseShellExecute = true
-                });
-
-                return;
-            }
-
-            if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
-            {
-                Process.Start("open", filePath);
-                return;
-            }
-
-            Process.Start("xdg-open", filePath);
-        });
+        catch (Exception ex) { return FileOperationResult.Error(ex); }
+        finally { try { if (staged != null && File.Exists(staged)) File.Delete(staged); } catch { } }
     }
 
-    private static Task<string?> ShowSaveDialogAsync(string suggestedFileName)
+    public Task<FileOperationResult> OpenFileAsync(string filePath) => OpenAsync(filePath, false);
+    public Task<FileOperationResult> OpenFolderAsync(string filePath) => OpenAsync(filePath, true);
+
+    private static Task<FileOperationResult> OpenAsync(string filePath, bool folder) => Task.Run(() =>
     {
-        return Task.Run(() =>
+        try
         {
-            if (!RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
-            {
-                // Fallback: save to Documents folder
-                var documentsPath = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
-                return Path.Combine(documentsPath, suggestedFileName);
-            }
+            var path = folder ? Path.GetDirectoryName(Path.GetFullPath(filePath))! : filePath;
+            if (folder ? !Directory.Exists(path) : !File.Exists(path))
+                throw new FileNotFoundException("Der gespeicherte Pfad ist nicht mehr vorhanden.");
+            var start = new ProcessStartInfo { UseShellExecute = true };
+            if (OperatingSystem.IsWindows()) start.FileName = path;
+            else { start.FileName = OperatingSystem.IsMacOS() ? "open" : "xdg-open"; start.ArgumentList.Add(path); }
+            using var process = Process.Start(start) ?? throw new IOException("Kein Programm zum Öffnen gefunden.");
+            return new FileOperationResult(FileOperationStatus.Success, folder ? "Ordner geöffnet." : "Datei geöffnet.");
+        }
+        catch (Exception ex)
+        {
+            return new FileOperationResult(FileOperationStatus.Error,
+                "Der Pfad konnte nicht geöffnet werden. Die gespeicherte Datei bleibt erhalten; bitte den Speicherort im Datei-Explorer öffnen.", filePath, ex.Message);
+        }
+    });
 
-            var extension = Path.GetExtension(suggestedFileName);
-            var filterName = extension == ".pdf" ? "PDF-Dateien" : "Dateien";
-            var filter = $"{filterName} (*{extension})|*{extension}|Alle Dateien (*.*)|*.*";
-
-            var script = $@"
-Add-Type -AssemblyName System.Windows.Forms
-$dialog = New-Object System.Windows.Forms.SaveFileDialog
-$dialog.Filter = '{filter}'
-$dialog.FileName = '{suggestedFileName.Replace("'", "''")}'
-$dialog.Title = 'Datei speichern'
-if ($dialog.ShowDialog() -eq 'OK') {{ $dialog.FileName }} else {{ '' }}
-";
-
-            var psi = new ProcessStartInfo
-            {
-                FileName = "powershell",
-                Arguments = $"-NoProfile -Command \"{script.Replace("\"", "\\\"\"")}\"",
-                RedirectStandardOutput = true,
-                UseShellExecute = false,
-                CreateNoWindow = true
-            };
-
-            using var process = Process.Start(psi);
-            if (process == null) return null;
-
-            var result = process.StandardOutput.ReadToEnd().Trim();
-            process.WaitForExit();
-
-            return string.IsNullOrWhiteSpace(result) ? null : result;
-        });
-    }
 }

src/Duempelkas.Infrastructure/Services/PdfStatementService.cs

@@ -66,6 +66,8 @@ public class PdfStatementService : IPdfStatementService
                 {
                     col.Item().Text(clubName).Bold().FontSize(20);
                     col.Item().Text(title).FontSize(14).FontColor(Colors.Grey.Darken1);
+                    col.Item().Text(year.HasValue ? $"Zeitraum: 01.01.{year} bis 31.12.{year}" : "Zeitraum: Alle Jahre").FontSize(9);
+                    col.Item().Text("Nur wirksame Buchungen. Umbuchungen zählen im einzelnen Konto als Zu- oder Abgang.").FontSize(8);
                     col.Item().PaddingTop(5).Text($"Erstellt am: {DateTime.Now:dd.MM.yyyy}").FontSize(8).FontColor(Colors.Grey.Medium);
                     col.Item().PaddingTop(10).LineHorizontal(1).LineColor(Colors.Grey.Lighten2);
                 });
@@ -94,7 +96,7 @@ public class PdfStatementService : IPdfStatementService
                                 .PaddingBottom(5).AlignRight().Text("Betrag").SemiBold();
                         });
 
-                        foreach (var entry in entries)
+                        foreach (var entry in entries.Where(e => !e.IsDeleted))
                         {
                             var titleText = entry.Title;
                             if (entry.IsTransfer && !string.IsNullOrEmpty(entry.LinkedAccountName))
@@ -127,11 +129,16 @@ public class PdfStatementService : IPdfStatementService
                             SummaryRow(summaryCol, $"Übertrag von {year.Value - 1}:", balance.CarryoverBalance);
                         }
 
+                        else
+                        {
+                            SummaryRow(summaryCol, "Anfangsbestand:", balance.CarryoverBalance);
+                        }
+
                         SummaryRow(summaryCol, year.HasValue ? "Einnahmen:" : "Einnahmen gesamt:", incomeValue);
                         SummaryRow(summaryCol, year.HasValue ? "Ausgaben:" : "Ausgaben gesamt:", -expenseValue);
                         summaryCol.Item().PaddingTop(5).Row(row =>
                         {
-                            row.RelativeItem().Text("Saldo:").Bold().FontSize(12);
+                            row.RelativeItem().Text(year.HasValue ? $"Kontostand am 31.12.{year}:" : "Kontostand nach allen Buchungen:").Bold().FontSize(12);
                             row.AutoItem().Text(FormatCurrency(balance.TotalBalance)).Bold().FontSize(12)
                                 .FontColor(balance.TotalBalance >= 0 ? Colors.Green.Darken1 : Colors.Red.Darken1);
                         });
@@ -302,6 +309,8 @@ public class PdfStatementService : IPdfStatementService
                         ? $"Übersicht aller Konten ({year.Value})"
                         : "Übersicht aller Konten";
                     col.Item().Text(headerTitle).FontSize(13).FontColor(Colors.Grey.Darken1);
+                    col.Item().Text(year.HasValue ? $"Zeitraum: 01.01.{year} bis 31.12.{year}; Endstände am 31.12.{year}." : "Zeitraum: Alle Jahre; Endstände nach allen Buchungen.").FontSize(9);
+                    col.Item().Text("Nur wirksame Buchungen. Interne Umbuchungen erscheinen einmal mit Minus und Plus; die Vereinssumme bleibt unverändert.").FontSize(8);
                     col.Item().PaddingTop(2).Text($"Gesamtvermögen: {FormatCurrency(totalClubBalance)}")
                         .FontSize(10)
                         .SemiBold()
@@ -338,15 +347,14 @@ public class PdfStatementService : IPdfStatementService
                             }
                         });
 
-                        if (year.HasValue && carryoverByAccountId is not null)
                         {
                             BodyCell(table, string.Empty);
                             BodyCell(table, string.Empty);
-                            BodyCell(table, $"Übertrag von {year.Value - 1}", alignRight: true);
+                            BodyCell(table, year.HasValue ? $"Übertrag von {year.Value - 1}" : "Anfangsbestand", alignRight: true);
 
                             foreach (var account in accounts)
                             {
-                                BodyAmountCell(table, carryoverByAccountId.GetValueOrDefault(account.Id));
+                                BodyAmountCell(table, carryoverByAccountId?.GetValueOrDefault(account.Id) ?? account.CarryoverBalance);
                             }
                         }
 

tests/Duempelkas.Tests/BackupServiceTests.cs

@@ -0,0 +1,84 @@
+using Duempelkas.Domain.Enums;
+using Duempelkas.Infrastructure;
+using Duempelkas.Infrastructure.Persistence;
+using Duempelkas.Infrastructure.Services;
+using Microsoft.Data.Sqlite;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.DependencyInjection;
+using Xunit;
+
+namespace Duempelkas.Tests;
+
+public sealed class BackupServiceTests : IDisposable
+{
+    private readonly string folder = Path.Combine(Path.GetTempPath(), "duempelkas-tests-" + Guid.NewGuid().ToString("N"));
+    private readonly ServiceProvider services;
+    private readonly BackupService backup;
+    private readonly EntryService entries;
+    private readonly int accountId;
+
+    public BackupServiceTests()
+    {
+        Directory.CreateDirectory(folder);
+        services = new ServiceCollection().AddInfrastructure($"Data Source={Path.Combine(folder, "active.db")};Pooling=False").BuildServiceProvider();
+        using var db = services.GetRequiredService<IDbContextFactory<FinanceDbContext>>().CreateDbContext();
+        db.Database.Migrate();
+        db.Database.ExecuteSqlRaw("PRAGMA journal_mode=WAL;");
+        db.Accounts.Add(new() { Name = "Isolierte Testkasse" });
+        db.SaveChanges();
+        accountId = db.Accounts.Single().Id;
+        backup = new BackupService(services.GetRequiredService<DatabaseLocation>());
+        entries = (EntryService)services.GetRequiredService<Duempelkas.App.Services.IEntryService>();
+    }
+
+    [Fact]
+    public async Task WalSnapshot_RestoresExactState_AndKeepsFallback()
+    {
+        var first = await entries.CreateEntryAsync(accountId, EntryType.Income, new(2026, 1, 1), "Gesichert", 12.50m);
+        var path = Path.Combine(folder, "snapshot.bak");
+        await backup.CreateBackupToAsync(path);
+        await entries.CreateEntryAsync(accountId, EntryType.Expense, new(2026, 1, 2), "Später", 4.20m);
+        var fallback = await backup.RestoreFromAsync(path);
+        var restored = await entries.GetEntriesAsync(accountId, (int?)null);
+        Assert.Single(restored);
+        Assert.Equal(first, restored[0]);
+        using var old = new SqliteConnection($"Data Source={fallback};Mode=ReadOnly;Pooling=False");
+        old.Open();
+        using var command = old.CreateCommand();
+        command.CommandText = "SELECT COUNT(*) FROM Entries";
+        Assert.Equal(2L, command.ExecuteScalar());
+    }
+
+    [Theory]
+    [InlineData(false)]
+    [InlineData(true)]
+    public async Task InvalidBackup_DoesNotChangeActiveData(bool sqlite)
+    {
+        await entries.CreateEntryAsync(accountId, EntryType.Income, new(2026, 1, 1), "Bleibt", 10m);
+        var path = Path.Combine(folder, "invalid.bak");
+        if (sqlite)
+        {
+            using var connection = new SqliteConnection($"Data Source={path};Pooling=False");
+            connection.Open();
+            using var command = connection.CreateCommand();
+            command.CommandText = "CREATE TABLE Unrelated (Id INTEGER)";
+            command.ExecuteNonQuery();
+        }
+        else await File.WriteAllTextAsync(path, "not a database");
+        await Assert.ThrowsAnyAsync<Exception>(() => backup.RestoreFromAsync(path));
+        Assert.Single(await entries.GetEntriesAsync(accountId, (int?)null));
+    }
+
+    [Fact]
+    public async Task MissingSource_AndActiveDestination_AreRejected()
+    {
+        await Assert.ThrowsAnyAsync<Exception>(() => backup.RestoreFromAsync(Path.Combine(folder, "missing.bak")));
+        await Assert.ThrowsAnyAsync<Exception>(() => backup.CreateBackupToAsync(Path.Combine(folder, "active.db")));
+    }
+
+    public void Dispose()
+    {
+        services.Dispose();
+        Directory.Delete(folder, true);
+    }
+}

tests/Duempelkas.Tests/DashboardPdfStatementServiceTests.cs

@@ -95,6 +95,62 @@ public class DashboardPdfStatementServiceTests : IDisposable
         System.Text.Encoding.ASCII.GetString(pdf.Take(4).ToArray()).Should().Be("%PDF");
     }
 
+    [Fact]
+    public async Task Exports_ExcludeDeleted_ExplainTransfers_AndMatchBalances()
+    {
+        var source = new Account { Name = "Barkasse", CarryoverBalance = 100m };
+        var target = new Account { Name = "Girokonto" };
+        _db.Accounts.AddRange(source, target);
+        await _db.SaveChangesAsync();
+        var options = new DbContextOptionsBuilder<FinanceDbContext>().UseSqlite(_connectionString).Options;
+        var factory = new TestDbContextFactory(options);
+        var entries = new EntryService(factory);
+        await entries.CreateEntryAsync(source.Id, EntryType.Income, new(2026, 1, 1), "Mitgliedsbeitrag", 12.50m);
+        await entries.CreateEntryAsync(source.Id, EntryType.Expense, new(2026, 1, 2), "Porto", 4.20m);
+        await entries.CreateTransferAsync(source.Id, target.Id, new(2026, 1, 3), "Zur Bank", 50m);
+        var deleted = await entries.CreateEntryAsync(source.Id, EntryType.Income, new(2026, 1, 4), "GELOESCHTE_TESTBUCHUNG", 999m);
+        await entries.DeleteEntryAsync(deleted.Id);
+        await entries.CreateEntryAsync(source.Id, EntryType.Income, new(2027, 1, 1), "ZUKUNFT_TESTBUCHUNG", 1m);
+        var balance = await new BalanceQueryService(factory).GetAccountBalanceAsync(source.Id, 2026);
+        Assert.Equal(58.30m, balance.TotalBalance);
+        var single = await _pdfService.GenerateStatementAsync(source.Id, 2026);
+        var combined = await _pdfService.GenerateDashboardStatementAsync(2026);
+        foreach (var pdf in new[] { single, combined })
+        {
+            var text = Extract(pdf);
+            Assert.Contains("Mitgliedsbeitrag", text);
+            Assert.Contains("Porto", text);
+            Assert.Contains("Zur Bank", text);
+            Assert.DoesNotContain("GELOESCHTE_TESTBUCHUNG", text);
+            Assert.DoesNotContain("ZUKUNFT_TESTBUCHUNG", text);
+            Assert.Contains("58,30", text);
+            Assert.Contains("31.12.2026", text);
+        }
+        Assert.Contains("108,30", Extract(combined));
+        Assert.Contains("an Girokonto", Extract(single));
+        var all = Extract(await _pdfService.GenerateStatementAsync(source.Id, (int?)null));
+        Assert.Contains("Alle Jahre", all);
+        Assert.Contains("Anfangsbestand", all);
+        Assert.Contains("59,30", all);
+        var evidence = Environment.GetEnvironmentVariable("DUEMPELKAS_PDF_EVIDENCE");
+        if (evidence != null)
+        {
+            Directory.CreateDirectory(evidence);
+            await File.WriteAllBytesAsync(Path.Combine(evidence, "single.pdf"), single);
+            await File.WriteAllBytesAsync(Path.Combine(evidence, "combined.pdf"), combined);
+            // Additional pages exercise repeated headers and the final summary.
+            for (var i = 0; i < 90; i++)
+                await entries.CreateEntryAsync(source.Id, EntryType.Income, new(2026, 2, 1), $"Lesbarkeitsprüfung Buchung {i + 1}", 1m);
+            await File.WriteAllBytesAsync(Path.Combine(evidence, "multipage.pdf"), await _pdfService.GenerateStatementAsync(source.Id, 2026));
+        }
+    }
+
+    private static string Extract(byte[] pdf)
+    {
+        using var document = UglyToad.PdfPig.PdfDocument.Open(pdf);
+        return string.Join("\n", document.GetPages().Select(page => UglyToad.PdfPig.DocumentLayoutAnalysis.TextExtractor.ContentOrderTextExtractor.GetText(page)));
+    }
+
     public void Dispose()
     {
         _db.Database.CloseConnection();

tests/Duempelkas.Tests/Duempelkas.Tests.csproj

@@ -9,6 +9,7 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.11.0" />
+    <PackageReference Include="PdfPig" Version="0.1.16" />
     <PackageReference Include="xunit" Version="2.9.3" />
     <PackageReference Include="xunit.runner.visualstudio" Version="4.0.1">
       <PrivateAssets>all</PrivateAssets>

tests/Duempelkas.Tests/FileOperationTests.cs

@@ -0,0 +1,41 @@
+using Duempelkas.App.Services;
+using Duempelkas.App.Services.Models;
+using Duempelkas.Infrastructure.Services;
+using Xunit;
+
+namespace Duempelkas.Tests;
+
+public class FileOperationTests
+{
+    [Fact]
+    public async Task Cancel_IsNeutral()
+    {
+        var service = new FileSaveService(new Dialog(null));
+        Assert.Equal(FileOperationStatus.Cancelled, (await service.SaveFileAsync([1], "test.pdf")).Status);
+    }
+
+    [Fact]
+    public async Task SaveAndFailure_AreDistinct_AndOpeningMissingFileIsError()
+    {
+        var folder = Path.Combine(Path.GetTempPath(), "duempelkas-files-" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(folder);
+        try
+        {
+            var path = Path.Combine(folder, "Prüfung.pdf");
+            var service = new FileSaveService(new Dialog(path));
+            Assert.Equal(FileOperationStatus.Success, (await service.SaveFileAsync([1, 2, 3], "test.pdf")).Status);
+            Assert.Equal(new byte[] { 1, 2, 3 }, await File.ReadAllBytesAsync(path));
+            // A directory cannot be overwritten as a file; the existing file is preserved.
+            Assert.Equal(FileOperationStatus.Error, (await new FileSaveService(new Dialog(folder)).SaveFileAsync([4], "test.pdf")).Status);
+            Assert.Equal(FileOperationStatus.Error, (await service.OpenFileAsync(Path.Combine(folder, "missing.pdf"))).Status);
+            Assert.Equal(new byte[] { 1, 2, 3 }, await File.ReadAllBytesAsync(path));
+        }
+        finally { Directory.Delete(folder, true); }
+    }
+
+    private sealed class Dialog(string? path) : IFileDialogService
+    {
+        public Task<string?> SaveAsync(string suggestedFileName) => Task.FromResult(path);
+        public Task<string?> OpenBackupAsync() => Task.FromResult(path);
+    }
+}