Phase 4: backups + import/export config

ConfigStore.SaveAsync now snapshots the previous config to
%ProgramData%\WebhookServer\backups\config-<timestamp>.json before
overwriting, retaining the last 30. Failures are silent so a
backup-write hiccup never blocks an actual save.

Three new admin pipe ops:
- list-backups: returns newest 50 entries with timestamps and sizes
- restore-backup: takes a fileName, refuses path-traversal chars,
  loads the named backup over the live config (which itself triggers
  a fresh backup of the current state via the SaveAsync hook)
- import-config: replaces the current config with a GUI-supplied
  ServerConfig, merging encrypted secrets where the GUI didn't supply
  new plaintext

GUI File menu items are wired:
- Import config: file picker -> ImportConfigAsync
- Export config: SaveFileDialog writes the current config as JSON
- Backups: dynamic submenu auto-refreshed when opened, listing
  backups with timestamp + size; click to confirm-and-restore

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

src/WebhookServer.Gui/MainWindow.xaml

@@ -27,9 +27,26 @@
             <MenuItem Header="_File">
                 <MenuItem Header="_New endpoint…" Command="{Binding AddEndpointCommand}" InputGestureText="Ctrl+N"/>
                 <Separator/>
-                <MenuItem Header="_Import config…" IsEnabled="False" ToolTip="Coming soon"/>
-                <MenuItem Header="_Export config…" IsEnabled="False" ToolTip="Coming soon"/>
-                <MenuItem Header="_Backups" IsEnabled="False" ToolTip="Coming soon"/>
+                <MenuItem Header="_Import config…" Command="{Binding ImportConfigCommand}"/>
+                <MenuItem Header="_Export config…" Command="{Binding ExportConfigCommand}"/>
+                <MenuItem Header="_Backups"
+                          ItemsSource="{Binding Backups}"
+                          SubmenuOpened="OnBackupsSubmenuOpened">
+                    <MenuItem.ItemContainerStyle>
+                        <Style TargetType="MenuItem">
+                            <Setter Property="Header">
+                                <Setter.Value>
+                                    <MultiBinding StringFormat="{}{0:yyyy-MM-dd HH:mm:ss}  ({1:n0} bytes)">
+                                        <Binding Path="SavedAt"/>
+                                        <Binding Path="SizeBytes"/>
+                                    </MultiBinding>
+                                </Setter.Value>
+                            </Setter>
+                            <Setter Property="Command" Value="{Binding DataContext.RestoreBackupCommand, RelativeSource={RelativeSource AncestorType=Window}}"/>
+                            <Setter Property="CommandParameter" Value="{Binding}"/>
+                        </Style>
+                    </MenuItem.ItemContainerStyle>
+                </MenuItem>
                 <Separator/>
                 <MenuItem Header="E_xit" Command="{Binding ExitCommand}"/>
             </MenuItem>

src/WebhookServer.Gui/MainWindow.xaml.cs

@@ -52,4 +52,10 @@ public partial class MainWindow : Window
         if (DataContext is MainViewModel vm && vm.EditEndpointCommand.CanExecute(null))
             vm.EditEndpointCommand.Execute(null);
     }
+
+    private async void OnBackupsSubmenuOpened(object sender, RoutedEventArgs e)
+    {
+        if (DataContext is MainViewModel vm)
+            await vm.RefreshBackupsCommand.ExecuteAsync(null);
+    }
 }

src/WebhookServer.Gui/Services/AdminPipeClient.cs

@@ -86,4 +86,18 @@ public sealed class AdminPipeClient
         var lst = resp.Data.Value.GetProperty("lines").Deserialize<List<LogLine>>(AdminProtocol.JsonOptions);
         return lst ?? new List<LogLine>();
     }
+
+    public async Task<List<BackupEntry>> ListBackupsAsync(CancellationToken ct = default)
+    {
+        var resp = await InvokeAsync(AdminOps.ListBackups, null, ct).ConfigureAwait(false);
+        if (!resp.Ok || resp.Data is null) return new List<BackupEntry>();
+        var lst = resp.Data.Value.GetProperty("backups").Deserialize<List<BackupEntry>>(AdminProtocol.JsonOptions);
+        return lst ?? new List<BackupEntry>();
+    }
+
+    public Task<AdminResponse> RestoreBackupAsync(string fileName, CancellationToken ct = default) =>
+        InvokeAsync(AdminOps.RestoreBackup, new RestoreBackupArgs { FileName = fileName }, ct);
+
+    public Task<AdminResponse> ImportConfigAsync(ServerConfig config, CancellationToken ct = default) =>
+        InvokeAsync(AdminOps.ImportConfig, config, ct);
 }

src/WebhookServer.Gui/ViewModels/MainViewModel.cs

@@ -175,6 +175,92 @@ public sealed partial class MainViewModel : ObservableObject
         }
     }
 
+    [ObservableProperty] private System.Collections.ObjectModel.ObservableCollection<BackupEntry> _backups = new();
+
+    [RelayCommand]
+    private async Task RefreshBackupsAsync()
+    {
+        try
+        {
+            var list = await _client.ListBackupsAsync().ConfigureAwait(false);
+            Application.Current.Dispatcher.Invoke(() =>
+            {
+                Backups.Clear();
+                foreach (var b in list) Backups.Add(b);
+            });
+        }
+        catch { /* ignore - backup listing isn't critical */ }
+    }
+
+    [RelayCommand]
+    private async Task RestoreBackupAsync(BackupEntry? entry)
+    {
+        if (entry is null) return;
+        var ok = MessageBox.Show(
+            $"Restore configuration from {entry.FileName} ({entry.SavedAt:yyyy-MM-dd HH:mm})?\n\nA backup of the current config will be saved first.",
+            "Restore backup",
+            MessageBoxButton.OKCancel,
+            MessageBoxImage.Question);
+        if (ok != MessageBoxResult.OK) return;
+        try
+        {
+            await _client.RestoreBackupAsync(entry.FileName).ConfigureAwait(false);
+            await RefreshAsync().ConfigureAwait(false);
+        }
+        catch (Exception ex) { ShowError("Restore failed", ex); }
+    }
+
+    [RelayCommand]
+    private async Task ExportConfigAsync()
+    {
+        try
+        {
+            var snap = await _client.GetConfigAsync().ConfigureAwait(false);
+            if (snap is null) { ShowError("Export failed", new InvalidOperationException("Service did not return a config.")); return; }
+
+            var dlg = new Microsoft.Win32.SaveFileDialog
+            {
+                FileName = $"webhook-server-config-{DateTime.Now:yyyyMMdd-HHmmss}.json",
+                DefaultExt = ".json",
+                Filter = "JSON config (*.json)|*.json",
+            };
+            if (dlg.ShowDialog() != true) return;
+
+            var json = System.Text.Json.JsonSerializer.Serialize(snap, WebhookServer.Core.Storage.ConfigJson.Pretty);
+            await System.IO.File.WriteAllTextAsync(dlg.FileName, json).ConfigureAwait(false);
+        }
+        catch (Exception ex) { ShowError("Export failed", ex); }
+    }
+
+    [RelayCommand]
+    private async Task ImportConfigAsync()
+    {
+        var dlg = new Microsoft.Win32.OpenFileDialog
+        {
+            Filter = "JSON config (*.json)|*.json",
+            CheckFileExists = true,
+        };
+        if (dlg.ShowDialog() != true) return;
+
+        try
+        {
+            var json = await System.IO.File.ReadAllTextAsync(dlg.FileName).ConfigureAwait(false);
+            var cfg = System.Text.Json.JsonSerializer.Deserialize<ServerConfig>(json, WebhookServer.Core.Storage.ConfigJson.Pretty);
+            if (cfg is null) throw new InvalidOperationException("File did not contain a valid config.");
+
+            var ok = MessageBox.Show(
+                $"Replace the current configuration with {dlg.FileName}?\n\nA backup of the current config will be saved first.",
+                "Import config",
+                MessageBoxButton.OKCancel,
+                MessageBoxImage.Warning);
+            if (ok != MessageBoxResult.OK) return;
+
+            await _client.ImportConfigAsync(cfg).ConfigureAwait(false);
+            await RefreshAsync().ConfigureAwait(false);
+        }
+        catch (Exception ex) { ShowError("Import failed", ex); }
+    }
+
     [RelayCommand]
     private async Task RestartServiceAsync()
     {