v0.13.0 — Report tool : timestamped backups + manual revert

The previous deploy mechanism kept the old version under {target}.old
just long enough to swap, then deleted it — no way back if the new
report had a runtime bug only visible at use time.

Now each deploy keeps the previous active version under
{FolderName}.backup-yyyyMMdd-HHmmss/. The N most recent are kept
(MaxBackups, default 3) and older ones are pruned in best-effort.

UI in Settings → Avancés → Outil Report :
- "Conserver N backups" input (0 = no history, back to v0.12 behavior)
- List of backups with date + size + cryptic folder name + per-row "↶ Revert"
- Confirmation dialog: "Revert to {date}? The currently deployed
  version will itself be saved as a new backup, so you can switch back."

Implementation
- IReportToolDeployer: + ListBackupsAsync, + RevertAsync, + BackupInfo,
  + DeployStatus.BackupNotFound.
- ReportToolDeployer: deploy renames {target} → backup-{ts}; PruneOldBackups
  trims to MaxBackups; RevertAsync atomically swaps current ↔ chosen
  backup, the previous current becoming itself a fresh backup.
- ReportBackupViewModel + DataTemplate for the list rows.
- Strings: backup labels, "↶ Revert", confirmation message.

Caveats documented in the design discussion:
- Backups cover ONLY the report tool files. DB migrations are not reverted
  (irreversible). If a migration broke the schema, that's a separate fix.
- No HTTP-HEAD post-deploy auto-revert: too fragile for false positives.
  Revert stays a deliberate manual action.

Versions bumped to 0.13.0.

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

installer/PSLauncher.iss

@@ -11,7 +11,7 @@
 
 #define MyAppName        "PROSERVE Launcher"
 #define MyAppShortName   "PSLauncher"
-#define MyAppVersion     "0.12.0"
+#define MyAppVersion     "0.13.0"
 #define MyAppPublisher   "ASTERION VR"
 #define MyAppURL         "https://asterionvr.com"
 #define MyAppExeName     "PSLauncher.exe"

src/PSLauncher.App/PSLauncher.App.csproj

@@ -15,9 +15,9 @@
     <Product>PROSERVE Launcher</Product>
     <Copyright>© 2026 ASTERION VR — All rights reserved</Copyright>
     <RootNamespace>PSLauncher.App</RootNamespace>
-    <Version>0.12.0</Version>
-    <AssemblyVersion>0.12.0.0</AssemblyVersion>
-    <FileVersion>0.12.0.0</FileVersion>
+    <Version>0.13.0</Version>
+    <AssemblyVersion>0.13.0.0</AssemblyVersion>
+    <FileVersion>0.13.0.0</FileVersion>
 
     <!-- Single-file self-contained publish profile (used by `dotnet publish`) -->
     <PublishSingleFile>true</PublishSingleFile>

src/PSLauncher.App/ViewModels/SettingsViewModel.cs

@@ -63,8 +63,12 @@ public sealed partial class SettingsViewModel : ObservableObject
     [ObservableProperty] private string _reportHtdocsRoot;
     [ObservableProperty] private string _reportFolderName;
     [ObservableProperty] private bool _reportAutoDeploy;
+    [ObservableProperty] private int _reportMaxBackups;
     [ObservableProperty] private string? _reportDeployStatus;
     [ObservableProperty] private bool _isDeployingReport;
+    public System.Collections.ObjectModel.ObservableCollection<ReportBackupViewModel> ReportBackups { get; }
+        = new();
+    public bool HasReportBackups => ReportBackups.Count > 0;
 
     public IReadOnlyList<LanguageOption> AvailableLanguages { get; } =
         PSLauncher.Core.Localization.Strings.Available
@@ -164,6 +168,9 @@ public sealed partial class SettingsViewModel : ObservableObject
         _reportHtdocsRoot = config.ReportTool.HtdocsRoot;
         _reportFolderName = config.ReportTool.FolderName;
         _reportAutoDeploy = config.ReportTool.AutoDeploy;
+        _reportMaxBackups = config.ReportTool.MaxBackups;
+        // Charge la liste de backups en arrière-plan (UI immédiate puis remplie quand prête)
+        _ = LoadReportBackupsAsync();
 
         LauncherVersion = Assembly.GetExecutingAssembly().GetName().Version?.ToString() ?? "0.0.0";
         MachineId = licenseService.GetMachineId();
@@ -287,6 +294,7 @@ public sealed partial class SettingsViewModel : ObservableObject
         _config.ReportTool.HtdocsRoot = ReportHtdocsRoot.Trim();
         _config.ReportTool.FolderName = ReportFolderName.Trim();
         _config.ReportTool.AutoDeploy = ReportAutoDeploy;
+        _config.ReportTool.MaxBackups = Math.Max(0, ReportMaxBackups);
 
         _configStore.Save(_config);
         _logger.LogInformation("Settings saved (language={Lang}, changed={Changed})", _config.Language, languageChanged);
@@ -494,4 +502,76 @@ public sealed partial class SettingsViewModel : ObservableObject
             IsReplayingMigrations = false;
         }
     }
+
+    // ===================== REPORT TOOL BACKUPS =====================
+
+    private async Task LoadReportBackupsAsync()
+    {
+        try
+        {
+            var list = await _reportDeployer.ListBackupsAsync(CancellationToken.None);
+            ReportBackups.Clear();
+            foreach (var b in list)
+                ReportBackups.Add(new ReportBackupViewModel(b, RevertReportToBackupAsync));
+            OnPropertyChanged(nameof(HasReportBackups));
+        }
+        catch (Exception ex)
+        {
+            _logger.LogDebug(ex, "Could not list report backups");
+        }
+    }
+
+    /// <summary>Appelé par chaque ligne du tableau de backups via son own command.</summary>
+    private async Task RevertReportToBackupAsync(BackupInfo backup)
+    {
+        var localDate = backup.TimestampUtc.ToLocalTime();
+        var dateLabel = Strings.FormatLongDate(localDate);
+        var confirm = MessageBox.Show(
+            Strings.MsgRevertReportConfirm(dateLabel),
+            Strings.MsgBoxRevertReport,
+            MessageBoxButton.YesNo, MessageBoxImage.Question, MessageBoxResult.No);
+        if (confirm != MessageBoxResult.Yes) return;
+
+        IsDeployingReport = true;
+        ReportDeployStatus = $"Revert vers {dateLabel}…";
+        try
+        {
+            var result = await _reportDeployer.RevertAsync(backup.FolderName, CancellationToken.None);
+            ReportDeployStatus = result.Status == DeployStatus.Deployed
+                ? Strings.MsgRevertReportSuccess(dateLabel)
+                : $"✗ {result.ErrorMessage}";
+            await LoadReportBackupsAsync();
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Revert report failed");
+            ReportDeployStatus = $"✗ {ex.Message}";
+        }
+        finally
+        {
+            IsDeployingReport = false;
+        }
+    }
+}
+
+/// <summary>
+/// Ligne du tableau "Backups disponibles" dans Settings → Avancés → Outil Report.
+/// Chaque instance porte sa propre commande Revert paramétrée pour ce backup.
+/// </summary>
+public sealed partial class ReportBackupViewModel : ObservableObject
+{
+    public BackupInfo Info { get; }
+    public string DateDisplay => Strings.FormatLongDate(Info.TimestampUtc.ToLocalTime());
+    public string SizeDisplay => Strings.SettingsReportBackupSize(Strings.FormatSize(Info.SizeBytes));
+    public string FolderName => Info.FolderName;
+
+    private readonly Func<BackupInfo, Task> _revertHandler;
+    public ReportBackupViewModel(BackupInfo info, Func<BackupInfo, Task> revertHandler)
+    {
+        Info = info;
+        _revertHandler = revertHandler;
+    }
+
+    [RelayCommand]
+    private Task Revert() => _revertHandler(Info);
 }

src/PSLauncher.App/Views/SettingsDialog.xaml

@@ -444,6 +444,22 @@
                                   Foreground="{StaticResource Brush.Text.Primary}"
                                   Content="{x:Static loc:Strings.SettingsReportAutoDeploy}" />
 
+                        <!-- Conserver N backups -->
+                        <Grid Margin="0,12,0,0">
+                            <Grid.ColumnDefinitions>
+                                <ColumnDefinition Width="*" />
+                                <ColumnDefinition Width="80" />
+                            </Grid.ColumnDefinitions>
+                            <TextBlock Grid.Column="0"
+                                       Text="{x:Static loc:Strings.SettingsReportMaxBackups}"
+                                       Foreground="{StaticResource Brush.Text.Secondary}"
+                                       FontSize="12" VerticalAlignment="Center" />
+                            <TextBox Grid.Column="1"
+                                     Text="{Binding ReportMaxBackups, UpdateSourceTrigger=PropertyChanged}"
+                                     Background="#1A1A20" Foreground="{StaticResource Brush.Text.Primary}"
+                                     BorderBrush="{StaticResource Brush.Border}" BorderThickness="1" Padding="8" />
+                        </Grid>
+
                         <Grid Margin="0,12,0,0">
                             <Grid.ColumnDefinitions>
                                 <ColumnDefinition Width="*" />
@@ -460,6 +476,52 @@
                                     Command="{Binding RedeployReportCommand}"
                                     IsEnabled="{Binding IsDeployingReport, Converter={StaticResource InverseBoolToBool}}" />
                         </Grid>
+
+                        <!-- Liste des backups disponibles avec bouton Revert par ligne -->
+                        <TextBlock Text="{x:Static loc:Strings.SettingsReportBackups}"
+                                   FontWeight="Bold" FontSize="11"
+                                   Foreground="{StaticResource Brush.Text.Secondary}"
+                                   Margin="0,16,0,6" />
+                        <TextBlock Text="{x:Static loc:Strings.SettingsReportNoBackups}"
+                                   Foreground="{StaticResource Brush.Text.Secondary}"
+                                   FontSize="12" FontStyle="Italic"
+                                   Visibility="{Binding HasReportBackups, Converter={StaticResource InverseBoolToVisibility}}" />
+                        <ItemsControl ItemsSource="{Binding ReportBackups}"
+                                      Visibility="{Binding HasReportBackups, Converter={StaticResource BoolToVisibility}}">
+                            <ItemsControl.ItemTemplate>
+                                <DataTemplate>
+                                    <Border Background="#1A1A20"
+                                            BorderBrush="{StaticResource Brush.Border}" BorderThickness="1"
+                                            CornerRadius="4" Padding="10,8" Margin="0,0,0,4">
+                                        <Grid>
+                                            <Grid.ColumnDefinitions>
+                                                <ColumnDefinition Width="*" />
+                                                <ColumnDefinition Width="Auto" />
+                                                <ColumnDefinition Width="Auto" />
+                                            </Grid.ColumnDefinitions>
+                                            <StackPanel Grid.Column="0" VerticalAlignment="Center">
+                                                <TextBlock Text="{Binding DateDisplay}"
+                                                           Foreground="{StaticResource Brush.Text.Primary}"
+                                                           FontSize="13" FontWeight="SemiBold" />
+                                                <TextBlock Text="{Binding SizeDisplay}"
+                                                           Foreground="{StaticResource Brush.Text.Secondary}"
+                                                           FontSize="11" />
+                                            </StackPanel>
+                                            <TextBlock Grid.Column="1"
+                                                       Text="{Binding FolderName}"
+                                                       FontFamily="Consolas" FontSize="10"
+                                                       Foreground="{StaticResource Brush.Text.Secondary}"
+                                                       VerticalAlignment="Center" Margin="0,0,12,0" />
+                                            <Button Grid.Column="2"
+                                                    Style="{StaticResource SecondaryButton}"
+                                                    Content="{x:Static loc:Strings.SettingsReportRevert}"
+                                                    Command="{Binding RevertCommand}"
+                                                    Padding="12,6" />
+                                        </Grid>
+                                    </Border>
+                                </DataTemplate>
+                            </ItemsControl.ItemTemplate>
+                        </ItemsControl>
                     </StackPanel>
                 </Border>
 

src/PSLauncher.Core/Localization/Strings.cs

@@ -511,6 +511,36 @@ public static class Strings
         "نشر أداة التقارير تلقائياً عند تثبيت نسخة جديدة"
     );
     public static string SettingsReportRedeploy   => T("📂  Re-déployer le Report maintenant", "📂  Re-deploy Report now", "📂  立即重新部署报告", "📂  ปรับใช้รายงานใหม่เดี๋ยวนี้", "📂  إعادة نشر التقرير الآن");
+
+    // ---- Backups Report tool ----
+    public static string SettingsReportBackups       => T("Backups disponibles", "Available backups", "可用备份", "สำรองข้อมูลที่มี", "النسخ الاحتياطية المتاحة");
+    public static string SettingsReportMaxBackups    => T("Conserver N backups", "Keep N backups", "保留 N 个备份", "เก็บสำรอง N ชุด", "الاحتفاظ بـ N نسخة احتياطية");
+    public static string SettingsReportRevert        => T("↶  Revert", "↶  Revert", "↶  还原", "↶  ย้อนกลับ", "↶  استرجاع");
+    public static string SettingsReportNoBackups     => T(
+        "Aucun backup pour l'instant. Le premier sera créé au prochain deploy.",
+        "No backups yet. The first one will be created on the next deploy.",
+        "暂无备份。下次部署时将创建第一个。",
+        "ยังไม่มีสำรองข้อมูล จะสร้างครั้งแรกในการปรับใช้ครั้งถัดไป",
+        "لا توجد نسخ احتياطية بعد. سيتم إنشاء أول نسخة عند النشر التالي."
+    );
+    public static string SettingsReportBackupSize(string size) => T(
+        $"taille : {size}", $"size: {size}", $"大小：{size}", $"ขนาด: {size}", $"الحجم: {size}"
+    );
+    public static string MsgBoxRevertReport          => T("Revert Outil Report", "Revert Report tool", "还原报告工具", "ย้อนกลับเครื่องมือรายงาน", "استرجاع أداة التقارير");
+    public static string MsgRevertReportConfirm(string date) => T(
+        $"Revenir à la version du {date} ?\n\nLa version actuellement déployée sera elle-même sauvegardée comme nouveau backup, donc tu pourras y revenir si besoin.",
+        $"Revert to the version from {date}?\n\nThe currently deployed version will itself be saved as a new backup, so you can switch back if needed.",
+        $"还原到 {date} 的版本？\n\n当前已部署的版本将作为新备份保存，因此您可以在需要时切换回去。",
+        $"ย้อนกลับไปยังเวอร์ชันของ {date}?\n\nเวอร์ชันที่ปรับใช้อยู่ในปัจจุบันจะถูกบันทึกเป็นสำรองใหม่ ดังนั้นคุณสามารถสลับกลับได้หากต้องการ",
+        $"العودة إلى نسخة {date}؟\n\nسيتم حفظ النسخة المنشورة حالياً كنسخة احتياطية جديدة، لذا يمكنك التبديل إليها إذا لزم الأمر."
+    );
+    public static string MsgRevertReportSuccess(string date) => T(
+        $"✓ Reverted vers la version du {date}",
+        $"✓ Reverted to version from {date}",
+        $"✓ 已还原到 {date} 的版本",
+        $"✓ ย้อนกลับเป็นเวอร์ชันของ {date} แล้ว",
+        $"✓ تم الاسترجاع إلى نسخة {date}"
+    );
     public static string MsgMigrationFailed(string detail) => T(
         $"Une migration de la base de données a échoué :\n\n{detail}\n\nLa version a été extraite mais la base n'a PAS été modifiée (rollback automatique).\nVérifie que XAMPP est démarré et que les paramètres de connexion sont corrects (Settings → Base de données), puis clique « Rejouer les migrations » dans Settings.",
         $"A database migration failed:\n\n{detail}\n\nThe version was extracted but the database was NOT modified (automatic rollback).\nMake sure XAMPP is running and the connection settings are correct (Settings → Database), then click « Replay migrations » in Settings.",

src/PSLauncher.Core/ReportTool/IReportToolDeployer.cs

@@ -3,6 +3,7 @@ namespace PSLauncher.Core.ReportTool;
 /// <summary>
 /// Déploie l'outil Report (page web hébergée dans XAMPP) depuis le sous-dossier
 /// <c>_report/</c> bundled dans chaque ZIP PROSERVE vers le htdocs local.
+/// Conserve N backups horodatés permettant un revert manuel via la UI Settings.
 /// </summary>
 public interface IReportToolDeployer
 {
@@ -11,18 +12,28 @@ public interface IReportToolDeployer
     /// <c>{HtdocsRoot}/{FolderName}/</c> via un rename atomique :
     /// <list type="number">
     ///   <item>copie récursive vers <c>{target}.new/</c></item>
-    ///   <item>rename de l'existant vers <c>{target}.old/</c> (s'il existait)</item>
+    ///   <item>rename de l'existant vers <c>{target}.backup-{yyyyMMdd-HHmmss}/</c></item>
     ///   <item>rename <c>.new</c> → final</item>
-    ///   <item>delete de <c>.old</c> en best-effort</item>
+    ///   <item>prune des vieux backups au-delà de <c>MaxBackups</c></item>
     /// </list>
-    /// Si _report/ absent du ZIP : skip silencieux. Si htdocs introuvable :
-    /// <see cref="DeployStatus.XamppNotFound"/>. Si erreur disque :
-    /// <see cref="DeployStatus.Failed"/> + message d'erreur.
     /// </summary>
     Task<DeployResult> DeployAsync(
         string installFolder,
         IProgress<DeployProgress>? progress,
         CancellationToken ct);
+
+    /// <summary>
+    /// Liste les backups horodatés disponibles dans <c>{HtdocsRoot}</c>, du plus
+    /// récent au plus ancien. Vide si aucun backup ou si htdocs introuvable.
+    /// </summary>
+    Task<IReadOnlyList<BackupInfo>> ListBackupsAsync(CancellationToken ct);
+
+    /// <summary>
+    /// Revient à un backup horodaté précis. Swap atomique : la version actuelle
+    /// est elle-même renommée en backup-{now} (donc le revert est lui-même
+    /// reversible), puis le backup choisi est renommé en version active.
+    /// </summary>
+    Task<DeployResult> RevertAsync(string backupFolderName, CancellationToken ct);
 }
 
 public enum DeployStatus
@@ -33,8 +44,10 @@ public enum DeployStatus
     XamppNotFound,
     /// <summary>Erreur I/O pendant la copie ou le rename.</summary>
     Failed,
-    /// <summary>Déploiement réussi.</summary>
+    /// <summary>Déploiement (ou revert) réussi.</summary>
     Deployed,
+    /// <summary>Revert demandé sur un backup qui n'existe pas / plus.</summary>
+    BackupNotFound,
 }
 
 public sealed record DeployResult(
@@ -45,3 +58,11 @@ public sealed record DeployResult(
     string? ErrorMessage = null);
 
 public sealed record DeployProgress(int FilesDone, int FilesTotal, string CurrentFilename);
+
+/// <summary>
+/// Métadonnées d'un backup horodaté présent dans <c>{HtdocsRoot}</c>.
+/// </summary>
+public sealed record BackupInfo(
+    string FolderName,           // ProserveReport.backup-20260503-143022
+    DateTime TimestampUtc,       // parsé depuis le suffixe du nom de dossier
+    long SizeBytes);

src/PSLauncher.Core/ReportTool/ReportToolDeployer.cs

@@ -1,17 +1,26 @@
+using System.Globalization;
 using Microsoft.Extensions.Logging;
 using PSLauncher.Models;
 
 namespace PSLauncher.Core.ReportTool;
 
 /// <summary>
-/// Implémentation simple : copy récursif + atomic rename. L'atomicité du rename
-/// garantit qu'Apache (qui sert les fichiers en parallèle) ne tombera jamais sur
-/// un état mi-déployé. Au pire il sert l'ancienne version pendant 1ms le temps
-/// du rename, puis sert la nouvelle.
+/// Implémentation : copy récursif + atomic rename + backups horodatés.
+/// L'atomicité du rename garantit qu'Apache (qui sert les fichiers en parallèle)
+/// ne tombera jamais sur un état mi-déployé. Au pire il sert l'ancienne version
+/// pendant 1ms le temps du rename, puis sert la nouvelle.
+///
+/// Backups : à chaque deploy, l'ancien dossier est conservé sous le nom
+/// <c>{FolderName}.backup-yyyyMMdd-HHmmss</c>. On garde les <c>MaxBackups</c>
+/// plus récents et on supprime les autres en best-effort. Permet le revert
+/// manuel via Settings → Avancés → Outil Report.
 /// </summary>
 public sealed class ReportToolDeployer : IReportToolDeployer
 {
     private const string SourceSubdir = "_report";
+    private const string BackupSuffix = ".backup-";
+    // Format trié-par-nom = trié-par-date (lexicographique == chronologique)
+    private const string TimestampFormat = "yyyyMMdd-HHmmss";
 
     private readonly Func<ReportToolConfig> _configProvider;
     private readonly ILogger<ReportToolDeployer> _logger;
@@ -47,15 +56,14 @@ public sealed class ReportToolDeployer : IReportToolDeployer
         }
 
         var stagingTarget = target + ".new";
-        var oldBackup = target + ".old";
+        var backupTarget = target + BackupSuffix + DateTime.UtcNow.ToString(TimestampFormat, CultureInfo.InvariantCulture);
 
         try
         {
-            // Nettoyage d'un éventuel résidu de tentative précédente
+            // Nettoyage d'un éventuel résidu de tentative précédente (le .new orphelin)
             if (Directory.Exists(stagingTarget)) Directory.Delete(stagingTarget, recursive: true);
-            if (Directory.Exists(oldBackup)) Directory.Delete(oldBackup, recursive: true);
 
-            // Énumère pour avoir un total + reporter la progression
+            // Copy avec progress
             var allFiles = Directory.EnumerateFiles(source, "*", SearchOption.AllDirectories).ToList();
             int total = allFiles.Count;
             long bytesTotal = 0;
@@ -79,29 +87,147 @@ public sealed class ReportToolDeployer : IReportToolDeployer
                 }
             }, ct).ConfigureAwait(false);
 
-            // Atomic swap
-            if (Directory.Exists(target)) Directory.Move(target, oldBackup);
+            // Atomic swap : current → backup-{ts}, .new → current
+            if (Directory.Exists(target))
+            {
+                Directory.Move(target, backupTarget);
+            }
             Directory.Move(stagingTarget, target);
 
-            // Cleanup ancienne version (best-effort, fichiers peuvent être verrouillés
-            // par Apache qui les sert encore — pas grave, sera nettoyé au prochain deploy)
-            if (Directory.Exists(oldBackup))
-            {
-                try { Directory.Delete(oldBackup, recursive: true); }
-                catch (Exception ex) { _logger.LogDebug(ex, "Could not clean .old backup, will retry next deploy"); }
-            }
+            // Prune des vieux backups (best-effort, ne bloque pas le retour)
+            PruneOldBackups(cfg);
 
-            _logger.LogInformation("Report tool deployed to {Target} ({Files} files, {Bytes} bytes)",
-                target, total, bytesTotal);
+            _logger.LogInformation("Report tool deployed to {Target} ({Files} files, {Bytes} bytes), backup at {Backup}",
+                target, total, bytesTotal, backupTarget);
             return new DeployResult(DeployStatus.Deployed, total, bytesTotal, target);
         }
         catch (Exception ex)
         {
             _logger.LogError(ex, "Failed to deploy report tool to {Target}", target);
-            // Best-effort cleanup pour ne pas laisser de staging à moitié écrit
             try { if (Directory.Exists(stagingTarget)) Directory.Delete(stagingTarget, recursive: true); }
             catch { /* ignore */ }
             return new DeployResult(DeployStatus.Failed, 0, 0, target, ex.Message);
         }
     }
+
+    public Task<IReadOnlyList<BackupInfo>> ListBackupsAsync(CancellationToken ct)
+    {
+        var cfg = _configProvider();
+        var prefix = cfg.FolderName + BackupSuffix;
+
+        if (!Directory.Exists(cfg.HtdocsRoot))
+            return Task.FromResult<IReadOnlyList<BackupInfo>>(Array.Empty<BackupInfo>());
+
+        var list = new List<BackupInfo>();
+        foreach (var dir in Directory.EnumerateDirectories(cfg.HtdocsRoot, prefix + "*", SearchOption.TopDirectoryOnly))
+        {
+            ct.ThrowIfCancellationRequested();
+            var name = Path.GetFileName(dir);
+            var tsPart = name.Substring(prefix.Length);
+            if (!DateTime.TryParseExact(tsPart, TimestampFormat, CultureInfo.InvariantCulture,
+                    DateTimeStyles.AssumeUniversal | DateTimeStyles.AdjustToUniversal, out var ts))
+            {
+                continue; // dossier non conforme, on ignore
+            }
+            long size = 0;
+            try
+            {
+                foreach (var f in Directory.EnumerateFiles(dir, "*", SearchOption.AllDirectories))
+                    size += new FileInfo(f).Length;
+            }
+            catch { /* size best-effort */ }
+            list.Add(new BackupInfo(name, ts, size));
+        }
+        // Plus récent en premier
+        list.Sort((a, b) => b.TimestampUtc.CompareTo(a.TimestampUtc));
+        return Task.FromResult<IReadOnlyList<BackupInfo>>(list);
+    }
+
+    public async Task<DeployResult> RevertAsync(string backupFolderName, CancellationToken ct)
+    {
+        var cfg = _configProvider();
+        var backupPath = Path.Combine(cfg.HtdocsRoot, backupFolderName);
+        var target = Path.Combine(cfg.HtdocsRoot, cfg.FolderName);
+
+        if (!Directory.Exists(backupPath))
+        {
+            return new DeployResult(DeployStatus.BackupNotFound, 0, 0, target,
+                $"Le backup {backupFolderName} n'existe plus.");
+        }
+
+        // Le revert lui-même crée un backup de l'état actuel, pour qu'on puisse
+        // revert le revert si besoin.
+        var newBackupForCurrent = target + BackupSuffix + DateTime.UtcNow.ToString(TimestampFormat, CultureInfo.InvariantCulture);
+
+        try
+        {
+            await Task.Run(() =>
+            {
+                ct.ThrowIfCancellationRequested();
+                if (Directory.Exists(target))
+                    Directory.Move(target, newBackupForCurrent);
+                Directory.Move(backupPath, target);
+            }, ct).ConfigureAwait(false);
+
+            // Compte les fichiers du backup restauré pour le retour
+            int files = 0;
+            long bytes = 0;
+            try
+            {
+                foreach (var f in Directory.EnumerateFiles(target, "*", SearchOption.AllDirectories))
+                {
+                    files++;
+                    bytes += new FileInfo(f).Length;
+                }
+            }
+            catch { /* best-effort */ }
+
+            PruneOldBackups(cfg);
+            _logger.LogInformation("Reverted to backup {Backup} ({Files} files), previous current saved as {New}",
+                backupFolderName, files, newBackupForCurrent);
+            return new DeployResult(DeployStatus.Deployed, files, bytes, target);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Revert to {Backup} failed", backupFolderName);
+            return new DeployResult(DeployStatus.Failed, 0, 0, target, ex.Message);
+        }
+    }
+
+    /// <summary>
+    /// Garde les <c>MaxBackups</c> plus récents, supprime les autres en best-effort.
+    /// Si <c>MaxBackups = 0</c>, supprime tous les backups (mode "no history").
+    /// </summary>
+    private void PruneOldBackups(ReportToolConfig cfg)
+    {
+        try
+        {
+            var prefix = cfg.FolderName + BackupSuffix;
+            var dirs = Directory.EnumerateDirectories(cfg.HtdocsRoot, prefix + "*", SearchOption.TopDirectoryOnly)
+                .Select(d => new { Path = d, Name = Path.GetFileName(d) })
+                // Tri descending par nom = descending par date (yyyyMMdd-HHmmss est lexicographique)
+                .OrderByDescending(d => d.Name, StringComparer.Ordinal)
+                .ToList();
+
+            int keep = Math.Max(0, cfg.MaxBackups);
+            for (int i = keep; i < dirs.Count; i++)
+            {
+                try
+                {
+                    Directory.Delete(dirs[i].Path, recursive: true);
+                    _logger.LogDebug("Pruned old report backup {Dir}", dirs[i].Name);
+                }
+                catch (Exception ex)
+                {
+                    // Apache peut tenir un handle sur un fichier (logs ouverts, etc.).
+                    // On retentera au prochain deploy. Pas bloquant.
+                    _logger.LogDebug(ex, "Could not prune backup {Dir} (will retry next deploy)", dirs[i].Name);
+                }
+            }
+        }
+        catch (Exception ex)
+        {
+            _logger.LogDebug(ex, "Backup pruning skipped");
+        }
+    }
 }

src/PSLauncher.Models/LocalConfig.cs

@@ -107,6 +107,15 @@ public sealed class ReportToolConfig
     public string HtdocsRoot { get; set; } = @"C:\xampp\htdocs";
     public string FolderName { get; set; } = "ProserveReport";
     public bool AutoDeploy { get; set; } = true;
+
+    /// <summary>
+    /// Nombre de backups horodatés à conserver dans htdocs après chaque deploy.
+    /// Format des dossiers : <c>{FolderName}.backup-yyyyMMdd-HHmmss</c>.
+    /// Permet le revert via Settings si le nouveau deploy a un bug visible.
+    /// 3 par défaut = couvre les dernières releases sans grossir trop le disque.
+    /// 0 = pas de backup (retourne au comportement v0.12.0).
+    /// </summary>
+    public int MaxBackups { get; set; } = 3;
 }
 
 public sealed class LicenseConfig

src/PSLauncher.Updater/PSLauncher.Updater.csproj

@@ -8,7 +8,7 @@
     <LangVersion>latest</LangVersion>
     <AssemblyName>PSLauncher.Updater</AssemblyName>
     <RootNamespace>PSLauncher.Updater</RootNamespace>
-    <Version>0.12.0</Version>
+    <Version>0.13.0</Version>
     <ApplicationIcon>..\PSLauncher.App\Resources\favicon.ico</ApplicationIcon>
     <Company>ASTERION VR</Company>
     <Copyright>© 2026 ASTERION VR — All rights reserved</Copyright>