Add host activity and DB browser, and keep dialogs, drag-drop, and idle maintenance responsive.

Co-authored-by: Cursor <cursoragent@cursor.com>

docs/Documentation.md

@@ -182,9 +182,15 @@ even when that NAS is currently offline — if the archive was indexed earlier.
 
 ---
 
+## Development tools
+
+**Tools → Development → Host activity…** opens a live monitor of the background host: maintenance, indexing jobs, hashing, transfers, and a rolling activity log. It refreshes about every 1.5 seconds while open and also reacts to push events; closing it stops the polling.
+
+**Tools → Development → Database…** opens a general SQLite viewer. It starts on the Workbench index (`%LocalAppData%\ExplorerWorkbench\index.db`) in read-only mode while the host holds the write lock. Use **Open file…** for any other `.db`, and choose write mode when the file is not locked. You can browse tables, run SQL, and — when writable — edit cells, insert rows, and delete rows.
+
 ## Duplicates
 
-**Tools → Storage → Duplicates**. Groups are hashed in the background (size → partial hash → full hash only when needed). Workbench distinguishes:
+**Tools → Storage → Duplicates**. Groups come from the **index** (hashed in the background: size → partial hash → full hash only when needed), not from a live walk of the disk. The list fills from the index first (largest groups at the top); missing copies are dropped afterwards without blocking the window. A finished full scan of the drive also marks missing trees deleted; cancelling a scan does not. Unmarked groups have no class label. After you mark a group, Workbench shows:
 
 | Class | Meaning |
 | --- | --- |

src/Explorer.Analysis/AnalysisService.cs

@@ -1,3 +1,4 @@
+using Explorer.Application;
 using Explorer.Domain;
 using Explorer.Domain.Abstractions;
 
@@ -5,6 +6,8 @@ namespace Explorer.Analysis;
 
 public sealed class AnalysisService
 {
+    private const int DuplicateHashChunk = 24;
+
     private readonly IIndexStore _store;
     private readonly AnalysisResultCache _cache = new();
     private readonly SemaphoreSlim _ready = new(1, 1);
@@ -93,15 +96,152 @@ public sealed class AnalysisService
         CancellationToken cancellationToken = default)
         => RunOffUiAsync(async ct =>
         {
-            var raw = await _store.Hashes.GetDuplicateGroupsAsync(null, null, Math.Max(take * 8, 400), ct)
-                .ConfigureAwait(false);
-            var ids = raw.SelectMany(g => g.Entries.Select(e => e.Id)).Distinct().ToList();
-            var relations = await _store.Relations.GetAmongAsync(ids, ct).ConfigureAwait(false);
-            return (IReadOnlyList<ClassifiedDuplicateGroup>)raw
-                .Select(g => DuplicateClassifier.ClassifyGroup(g, DuplicateClassifier.RelationsFor(g.Entries, relations)))
-                .ToList();
+            var list = new List<ClassifiedDuplicateGroup>();
+            await StreamCoreAsync(take, list.Add, verifyPresence: true, ct).ConfigureAwait(false);
+            return (IReadOnlyList<ClassifiedDuplicateGroup>)list;
         }, cancellationToken);
 
+    public Task<IReadOnlyList<(long SourceId, string PathRel)>> StreamClassifiedDuplicatesAsync(
+        int take,
+        IProgress<ClassifiedDuplicateGroup> progress,
+        CancellationToken cancellationToken = default)
+        => StreamClassifiedDuplicatesAsync(take, progress, verifyPresence: false, cancellationToken);
+
+    public Task<IReadOnlyList<(long SourceId, string PathRel)>> StreamClassifiedDuplicatesAsync(
+        int take,
+        IProgress<ClassifiedDuplicateGroup> progress,
+        bool verifyPresence,
+        CancellationToken cancellationToken = default)
+        => RunOffUiAsync(
+            ct => StreamCoreAsync(take, progress.Report, verifyPresence, ct),
+            cancellationToken);
+
+    private async Task<IReadOnlyList<(long SourceId, string PathRel)>> StreamCoreAsync(
+        int take,
+        Action<ClassifiedDuplicateGroup> emit,
+        bool verifyPresence,
+        CancellationToken cancellationToken)
+    {
+        var limit = Math.Max(take * 8, 400);
+        var hashes = await _store.Hashes.GetDuplicateHashesAsync(null, null, limit, cancellationToken)
+            .ConfigureAwait(false);
+        var sources = (await _store.Sources.GetAllAsync(cancellationToken).ConfigureAwait(false))
+            .ToDictionary(s => s.Id);
+        var missing = new List<MissingCopy>();
+        for (var offset = 0; offset < hashes.Count; offset += DuplicateHashChunk)
+        {
+            cancellationToken.ThrowIfCancellationRequested();
+            var chunk = hashes.Skip(offset).Take(DuplicateHashChunk).ToList();
+            var groups = await _store.Hashes.GetDuplicateGroupsByHashesAsync(chunk, cancellationToken)
+                .ConfigureAwait(false);
+            var kept = new List<DuplicateGroup>();
+            foreach (var group in groups)
+            {
+                var present = verifyPresence
+                    ? KeepPresentCopies(group, sources, missing)
+                    : group.Entries.ToList();
+                if (present.Count < 2)
+                {
+                    continue;
+                }
+
+                kept.Add(new DuplicateGroup
+                {
+                    SizeBytes = group.SizeBytes,
+                    Hash = group.Hash,
+                    Entries = present,
+                    SameFileId = DuplicateClassifier.IsHardlinkOnly(present)
+                });
+            }
+
+            var ids = kept.SelectMany(g => g.Entries.Select(e => e.Id)).Distinct().ToList();
+            var relations = await _store.Relations.GetAmongAsync(ids, cancellationToken).ConfigureAwait(false);
+            foreach (var group in kept)
+            {
+                emit(DuplicateClassifier.ClassifyGroup(
+                    group,
+                    DuplicateClassifier.RelationsFor(group.Entries, relations)));
+            }
+        }
+
+        if (_store.CanWrite && missing.Count > 0)
+        {
+            await TombstoneMissingAsync(missing, sources, cancellationToken).ConfigureAwait(false);
+        }
+
+        return missing
+            .Select(m => (m.SourceId, IndexedPathPresence.ReconcilePath(m.PathRel, m.Prefix)))
+            .Distinct()
+            .ToList();
+    }
+
+    private static List<IndexEntry> KeepPresentCopies(
+        DuplicateGroup group,
+        IReadOnlyDictionary<long, Source> sources,
+        List<MissingCopy> missing)
+    {
+        var kept = new List<IndexEntry>(group.Entries.Count);
+        foreach (var entry in group.Entries)
+        {
+            if (!sources.TryGetValue(entry.SourceId, out var source)
+                || string.IsNullOrWhiteSpace(source.LastRootPath)
+                || !IndexedPathPresence.RootReachable(source.LastRootPath))
+            {
+                kept.Add(entry);
+                continue;
+            }
+
+            if (IndexedPathPresence.FileExists(source.LastRootPath, entry.PathRel))
+            {
+                kept.Add(entry);
+                continue;
+            }
+
+            var prefix = IndexedPathPresence.HighestMissingPrefix(source.LastRootPath, entry.PathRel)
+                         ?? entry.PathRel;
+            missing.Add(new MissingCopy(entry.SourceId, entry.Id, entry.PathRel, prefix, source.LastRootPath));
+        }
+
+        return kept;
+    }
+
+    private async Task TombstoneMissingAsync(
+        IReadOnlyList<MissingCopy> missing,
+        IReadOnlyDictionary<long, Source> sources,
+        CancellationToken cancellationToken)
+    {
+        var now = DateTimeOffset.UtcNow;
+        var prefixes = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
+        foreach (var item in missing)
+        {
+            if (!item.Prefix.Equals(item.PathRel, StringComparison.OrdinalIgnoreCase)
+                && sources.TryGetValue(item.SourceId, out var source)
+                && !string.IsNullOrWhiteSpace(source.LastRootPath)
+                && !IndexedPathPresence.DirectoryExists(PathRules.Combine(source.LastRootPath, item.Prefix)))
+            {
+                var key = item.SourceId + "|" + item.Prefix;
+                if (!prefixes.Add(key))
+                {
+                    continue;
+                }
+
+                var folder = await _store.Entries.GetByPathAsync(item.SourceId, item.Prefix, cancellationToken)
+                    .ConfigureAwait(false);
+                if (folder is not null)
+                {
+                    await _store.Entries.TombstoneAsync(folder.Id, now, cancellationToken).ConfigureAwait(false);
+                }
+
+                await _store.Entries.TombstoneByPathPrefixAsync(item.SourceId, item.Prefix, now, cancellationToken)
+                    .ConfigureAwait(false);
+            }
+            else
+            {
+                await _store.Entries.TombstoneAsync(item.EntryId, now, cancellationToken).ConfigureAwait(false);
+            }
+        }
+    }
+
     public Task MarkDuplicateGroupAsync(
         IReadOnlyList<IndexEntry> entries,
         FileRelationKind kind,
@@ -156,4 +296,11 @@ public sealed class AnalysisService
         return await Task.Run(async () => await work(cancellationToken).ConfigureAwait(false), cancellationToken)
             .ConfigureAwait(false);
     }
+
+    private readonly record struct MissingCopy(
+        long SourceId,
+        long EntryId,
+        string PathRel,
+        string Prefix,
+        string Root);
 }

src/Explorer.Analysis/DuplicateAndHistory.cs

@@ -11,18 +11,30 @@ public sealed class DuplicateHashWorker : BackgroundService, IIdleHashWork
 {
     private readonly IIndexStore _store;
     private readonly IHydrationGuard _hydration;
+    private readonly IHostActivitySink _activity;
     private readonly ILogger<DuplicateHashWorker> _logger;
+    private readonly object _pendingGate = new();
+    private long _pendingCount;
+    private DateTimeOffset _pendingCountUtc = DateTimeOffset.MinValue;
+    private int _pendingRefreshBusy;
     private volatile bool _paused = true;
     private volatile bool _userRequested;
+    private volatile string? _currentPath;
 
-    public DuplicateHashWorker(IIndexStore store, IHydrationGuard hydration, ILogger<DuplicateHashWorker> logger)
+    public DuplicateHashWorker(
+        IIndexStore store,
+        IHydrationGuard hydration,
+        ILogger<DuplicateHashWorker> logger,
+        IHostActivitySink? activity = null)
     {
         _store = store;
         _hydration = hydration;
         _logger = logger;
+        _activity = activity ?? NullHostActivitySink.Instance;
     }
 
     public bool IsPaused => _paused && !_userRequested;
+    public string? CurrentPath => _currentPath;
     public void Pause() => _paused = true;
     public void Resume() => _paused = false;
     public void BeginUserRequested() => _userRequested = true;
@@ -30,6 +42,61 @@ public sealed class DuplicateHashWorker : BackgroundService, IIdleHashWork
     public async Task<bool> HasPendingAsync(CancellationToken cancellationToken = default)
         => await _store.Hashes.HasPendingAsync(cancellationToken).ConfigureAwait(false);
 
+    public Task<long> CountPendingAsync(CancellationToken cancellationToken = default)
+    {
+        long cached;
+        var never = false;
+        lock (_pendingGate)
+        {
+            cached = _pendingCount;
+            never = _pendingCountUtc == DateTimeOffset.MinValue;
+            if (!never && DateTimeOffset.UtcNow - _pendingCountUtc < TimeSpan.FromSeconds(15))
+            {
+                return Task.FromResult(cached);
+            }
+        }
+
+        if (never)
+        {
+            return RefreshPendingCountAsync(cancellationToken);
+        }
+
+        if (Interlocked.CompareExchange(ref _pendingRefreshBusy, 1, 0) == 0)
+        {
+            _ = RefreshPendingCountInBackgroundAsync();
+        }
+
+        return Task.FromResult(cached);
+    }
+
+    private async Task RefreshPendingCountInBackgroundAsync()
+    {
+        try
+        {
+            await RefreshPendingCountAsync(CancellationToken.None).ConfigureAwait(false);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogDebug(ex, "Background hash-pending count failed");
+        }
+        finally
+        {
+            Interlocked.Exchange(ref _pendingRefreshBusy, 0);
+        }
+    }
+
+    private async Task<long> RefreshPendingCountAsync(CancellationToken cancellationToken)
+    {
+        var count = await _store.Hashes.CountPendingAsync(cancellationToken).ConfigureAwait(false);
+        lock (_pendingGate)
+        {
+            _pendingCount = count;
+            _pendingCountUtc = DateTimeOffset.UtcNow;
+        }
+
+        return count;
+    }
+
     public async Task ProcessPendingAsync(CancellationToken cancellationToken)
     {
         var batch = await _store.Hashes.DequeueAsync(8, cancellationToken).ConfigureAwait(false);
@@ -46,6 +113,8 @@ public sealed class DuplicateHashWorker : BackgroundService, IIdleHashWork
             }
 
             var path = PathRules.Combine(item.RootPath, item.PathRel);
+            _currentPath = path;
+            _activity.Record("Hash", item.State + " · " + path);
             try
             {
                 if (!File.Exists(path))
@@ -90,6 +159,10 @@ public sealed class DuplicateHashWorker : BackgroundService, IIdleHashWork
                 _logger.LogDebug(ex, "Hash failed for {Path}", path);
                 await _store.Hashes.MarkErrorAsync(item.EntryId, cancellationToken).ConfigureAwait(false);
             }
+            finally
+            {
+                _currentPath = null;
+            }
         }
     }
 

src/Explorer.App/DatabaseWindow.xaml

@@ -0,0 +1,78 @@
+<Window x:Class="Explorer.App.DatabaseWindow"
+        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        Title="Database"
+        Icon="pack://application:,,,/Assets/explorer-workbench.ico"
+        Height="720" Width="1100"
+        MinHeight="480" MinWidth="800"
+        WindowStartupLocation="CenterOwner"
+        Background="{DynamicResource Bg}" Foreground="{DynamicResource Fg}">
+  <DockPanel Margin="12">
+    <DockPanel DockPanel.Dock="Bottom" Margin="0,10,0,0">
+      <Button DockPanel.Dock="Right" Content="Close" MinWidth="88" Height="30" Click="OnClose" Margin="8,0,0,0"/>
+      <TextBlock Text="{Binding Status}" VerticalAlignment="Center" Foreground="{DynamicResource FgMuted}"
+                 TextTrimming="CharacterEllipsis"/>
+    </DockPanel>
+
+    <DockPanel DockPanel.Dock="Top" Margin="0,0,0,8">
+      <Button DockPanel.Dock="Right" Content="Close DB" MinWidth="80" Height="28"
+              Command="{Binding CloseDatabaseCommand}" Margin="6,0,0,0"/>
+      <Button DockPanel.Dock="Right" Content="Open file…" MinWidth="90" Height="28"
+              Click="OnOpenFile" Margin="6,0,0,0"/>
+      <Button DockPanel.Dock="Right" Content="Open Workbench index" MinWidth="150" Height="28"
+              Command="{Binding OpenWorkbenchIndexCommand}" Margin="6,0,0,0"/>
+      <StackPanel>
+        <TextBlock Text="{Binding PathLabel}" FontWeight="SemiBold" TextTrimming="CharacterEllipsis"/>
+        <TextBlock Text="{Binding ModeLabel}" Foreground="{DynamicResource FgMuted}" FontSize="11"/>
+      </StackPanel>
+    </DockPanel>
+
+    <Grid>
+      <Grid.ColumnDefinitions>
+        <ColumnDefinition Width="220"/>
+        <ColumnDefinition Width="8"/>
+        <ColumnDefinition Width="*"/>
+      </Grid.ColumnDefinitions>
+      <DockPanel>
+        <DockPanel DockPanel.Dock="Top" Margin="0,0,0,6">
+          <Button DockPanel.Dock="Right" Content="↻" Width="28" Height="26"
+                  Command="{Binding RefreshTablesCommand}" ToolTip="Refresh tables"/>
+          <TextBlock Text="Tables" FontWeight="SemiBold" VerticalAlignment="Center"/>
+        </DockPanel>
+        <ListBox ItemsSource="{Binding Tables}" SelectedItem="{Binding SelectedTable}"/>
+      </DockPanel>
+
+      <DockPanel Grid.Column="2">
+        <DockPanel DockPanel.Dock="Top" Margin="0,0,0,8">
+          <Button DockPanel.Dock="Right" Content="Run SQL" MinWidth="80" Height="28"
+                  Command="{Binding RunSqlCommand}" Margin="8,0,0,0"/>
+          <TextBox Text="{Binding Sql, UpdateSourceTrigger=PropertyChanged}" AcceptsReturn="True"
+                   Height="56" TextWrapping="Wrap" VerticalScrollBarVisibility="Auto"
+                   FontFamily="Consolas"/>
+        </DockPanel>
+        <DockPanel DockPanel.Dock="Top" Margin="0,0,0,8">
+          <TextBlock DockPanel.Dock="Left" Text="{Binding PageLabel}" VerticalAlignment="Center"
+                     Foreground="{DynamicResource FgMuted}" Margin="0,0,12,0"/>
+          <Button DockPanel.Dock="Left" Content="Prev" MinWidth="60" Height="26"
+                  Command="{Binding PrevPageCommand}" Margin="0,0,6,0"/>
+          <Button DockPanel.Dock="Left" Content="Next" MinWidth="60" Height="26"
+                  Command="{Binding NextPageCommand}" Margin="0,0,12,0"/>
+          <Button DockPanel.Dock="Left" Content="Edit cell…" MinWidth="80" Height="26"
+                  Click="OnEditCell" IsEnabled="{Binding CanWrite}" Margin="0,0,6,0"/>
+          <Button DockPanel.Dock="Left" Content="Insert row…" MinWidth="90" Height="26"
+                  Click="OnInsertRow" IsEnabled="{Binding CanWrite}" Margin="0,0,6,0"/>
+          <Button DockPanel.Dock="Left" Content="Delete row" MinWidth="80" Height="26"
+                  Command="{Binding DeleteSelectedRowCommand}" IsEnabled="{Binding CanWrite}"/>
+        </DockPanel>
+        <ListView x:Name="GridViewHost"
+                  ItemsSource="{Binding Rows}"
+                  SelectedItem="{Binding SelectedRow}"
+                  MouseDoubleClick="OnRowDoubleClick">
+          <ListView.View>
+            <GridView x:Name="ResultGrid"/>
+          </ListView.View>
+        </ListView>
+      </DockPanel>
+    </Grid>
+  </DockPanel>
+</Window>

src/Explorer.App/DatabaseWindow.xaml.cs

@@ -0,0 +1,159 @@
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Data;
+using System.Windows.Input;
+using Explorer.Presentation.ViewModels;
+using Microsoft.Win32;
+
+namespace Explorer.App;
+
+public partial class DatabaseWindow : Window
+{
+    public DatabaseWindow(DatabaseViewerViewModel vm)
+    {
+        InitializeComponent();
+        DataContext = vm;
+        ViewModel = vm;
+        vm.GridChanged += (_, _) => RebuildColumns();
+        ModelessWindowClose.EnableEscape(this);
+        Closed += async (_, _) => await vm.DisposeAsync().ConfigureAwait(true);
+        Loaded += async (_, _) => await vm.OpenIndexAsync(preferWrite: false).ConfigureAwait(true);
+    }
+
+    public DatabaseViewerViewModel ViewModel { get; }
+
+    private void OnClose(object sender, RoutedEventArgs e) => Close();
+
+    private void RebuildColumns()
+    {
+        ResultGrid.Columns.Clear();
+        for (var i = 0; i < ViewModel.Columns.Count; i++)
+        {
+            var index = i;
+            var header = ViewModel.Columns[i];
+            ResultGrid.Columns.Add(new GridViewColumn
+            {
+                Header = header,
+                Width = header.Equals("_rowid_", StringComparison.OrdinalIgnoreCase) ? 70 : 140,
+                DisplayMemberBinding = new Binding($"Cells[{index}]")
+            });
+        }
+    }
+
+    private void OnOpenFile(object sender, RoutedEventArgs e)
+    {
+        var dlg = new OpenFileDialog
+        {
+            Title = "Open SQLite database",
+            Filter = "SQLite databases (*.db;*.sqlite;*.sqlite3)|*.db;*.sqlite;*.sqlite3|All files (*.*)|*.*"
+        };
+        if (dlg.ShowDialog(this) == true)
+        {
+            var write = MessageBox.Show(
+                this,
+                "Open for writing? Choose No for read-only.",
+                "Database",
+                MessageBoxButton.YesNoCancel,
+                MessageBoxImage.Question);
+            if (write == MessageBoxResult.Cancel)
+            {
+                return;
+            }
+
+            _ = ViewModel.OpenPathAsync(dlg.FileName, preferWrite: write == MessageBoxResult.Yes);
+        }
+    }
+
+    private async void OnEditCell(object sender, RoutedEventArgs e)
+        => await EditSelectedCellAsync().ConfigureAwait(true);
+
+    private async void OnRowDoubleClick(object sender, MouseButtonEventArgs e)
+        => await EditSelectedCellAsync().ConfigureAwait(true);
+
+    private async Task EditSelectedCellAsync()
+    {
+        if (!ViewModel.CanWrite || ViewModel.SelectedRow is null || string.IsNullOrWhiteSpace(ViewModel.SelectedTable))
+        {
+            return;
+        }
+
+        var columns = ViewModel.EditableColumns();
+        if (columns.Count == 0)
+        {
+            return;
+        }
+
+        var column = Prompt("Column to edit", string.Join(", ", columns.Take(8)) + (columns.Count > 8 ? "…" : ""), columns[0]);
+        if (column is null || !columns.Contains(column, StringComparer.OrdinalIgnoreCase))
+        {
+            return;
+        }
+
+        var index = ViewModel.Columns.ToList().FindIndex(c => c.Equals(column, StringComparison.OrdinalIgnoreCase));
+        var current = index >= 0 && index < ViewModel.SelectedRow.Cells.Count
+            ? ViewModel.SelectedRow.Cells[index]
+            : "";
+        var next = Prompt("New value for " + column, "Leave empty for NULL.", current);
+        if (next is null)
+        {
+            return;
+        }
+
+        try
+        {
+            await ViewModel.UpdateSelectedCellAsync(column, string.IsNullOrEmpty(next) ? null : next)
+                .ConfigureAwait(true);
+        }
+        catch (Exception ex)
+        {
+            MessageBox.Show(this, ex.Message, "Database", MessageBoxButton.OK, MessageBoxImage.Warning);
+        }
+    }
+
+    private async void OnInsertRow(object sender, RoutedEventArgs e)
+    {
+        if (!ViewModel.CanWrite || string.IsNullOrWhiteSpace(ViewModel.SelectedTable))
+        {
+            return;
+        }
+
+        var columns = ViewModel.EditableColumns();
+        if (columns.Count == 0)
+        {
+            MessageBox.Show(this, "Load a table first so columns are known.", "Database");
+            return;
+        }
+
+        var values = new Dictionary<string, object?>(StringComparer.OrdinalIgnoreCase);
+        foreach (var column in columns)
+        {
+            var value = Prompt("Value for " + column, "Cancel skips this column. Empty = NULL.", "");
+            if (value is null)
+            {
+                continue;
+            }
+
+            values[column] = string.IsNullOrEmpty(value) ? null : value;
+        }
+
+        if (values.Count == 0)
+        {
+            return;
+        }
+
+        try
+        {
+            await ViewModel.InsertRowAsync(values).ConfigureAwait(true);
+        }
+        catch (Exception ex)
+        {
+            MessageBox.Show(this, ex.Message, "Database", MessageBoxButton.OK, MessageBoxImage.Warning);
+        }
+    }
+
+    private string? Prompt(string title, string message, string initial)
+    {
+        var dlg = new PromptWindow(title, message, initial) { Owner = this };
+        return dlg.ShowDialog() == true ? dlg.Value : null;
+    }
+}

src/Explorer.App/DocumentationWindow.xaml

@@ -9,9 +9,9 @@
         Background="{DynamicResource Bg}" Foreground="{DynamicResource Fg}">
   <DockPanel>
     <DockPanel DockPanel.Dock="Bottom" Margin="16,8,16,16">
-      <Button DockPanel.Dock="Right" Content="Close" MinWidth="88" Height="32" IsCancel="True" Margin="8,0,0,0"/>
+      <Button DockPanel.Dock="Right" Content="Close" MinWidth="88" Height="32" Click="OnClose" Margin="8,0,0,0"/>
       <Button DockPanel.Dock="Right" Content="Open file" MinWidth="88" Height="32" Click="OnOpenFile"
-              x:Name="OpenFileButton" Margin="8,0,0,0"/>
+              x:Name="OpenFileButton" IsEnabled="False" Margin="8,0,0,0"/>
       <Button DockPanel.Dock="Right" Content="Reload" MinWidth="88" Height="32" Click="OnReload" Margin="8,0,0,0"/>
       <TextBlock x:Name="SourceLabel" VerticalAlignment="Center" TextWrapping="Wrap"
                  Foreground="{DynamicResource FgMuted}"/>

src/Explorer.App/DocumentationWindow.xaml.cs

@@ -11,14 +11,19 @@ public partial class DocumentationWindow : Window
 {
     private FlowDocument? _document;
     private bool _suppressToc;
+    private int _renderGeneration;
 
     public DocumentationWindow()
     {
         InitializeComponent();
-        Loaded += (_, _) => Render();
+        ModelessWindowClose.EnableEscape(this);
+        Loaded += async (_, _) => await RenderAsync().ConfigureAwait(true);
     }
 
-    private void OnReload(object sender, RoutedEventArgs e) => Render();
+    private void OnClose(object sender, RoutedEventArgs e) => Close();
+
+    private async void OnReload(object sender, RoutedEventArgs e)
+        => await RenderAsync().ConfigureAwait(true);
 
     private void OnOpenFile(object sender, RoutedEventArgs e)
     {
@@ -44,10 +49,35 @@ public partial class DocumentationWindow : Window
         }
     }
 
-    private void Render()
+    private async Task RenderAsync()
     {
-        var loaded = DocumentationLoader.Load();
-        var parsed = MarkdownParser.Parse(loaded.Markdown);
+        var generation = Interlocked.Increment(ref _renderGeneration);
+        SourceLabel.Text = "Loading…";
+        LoadedDocumentation loaded;
+        MarkdownDocument parsed;
+        try
+        {
+            (loaded, parsed) = await Task.Run(() =>
+            {
+                var document = DocumentationLoader.Load();
+                return (document, MarkdownParser.Parse(document.Markdown));
+            }).ConfigureAwait(true);
+        }
+        catch (Exception ex)
+        {
+            if (generation == _renderGeneration)
+            {
+                SourceLabel.Text = "Could not load documentation: " + ex.Message;
+            }
+
+            return;
+        }
+
+        if (generation != _renderGeneration || !IsLoaded)
+        {
+            return;
+        }
+
         var brushes = new DocumentationBrushes(
             Brush("Fg"),
             Brush("FgMuted"),

src/Explorer.App/GitChangesWindow.xaml

@@ -9,7 +9,7 @@
         Background="{DynamicResource Bg}" Foreground="{DynamicResource Fg}">
   <DockPanel Margin="16">
     <DockPanel DockPanel.Dock="Bottom" Margin="0,12,0,0">
-      <Button DockPanel.Dock="Right" Content="Close" MinWidth="88" Height="32" IsCancel="True" Margin="8,0,0,0"/>
+      <Button DockPanel.Dock="Right" Content="Close" MinWidth="88" Height="32" Click="OnClose" Margin="8,0,0,0"/>
       <Button DockPanel.Dock="Right" Content="Commit…" MinWidth="88" Height="32"
               Click="OnCommit" IsEnabled="{Binding CanCommit}" Margin="8,0,0,0"/>
       <Button DockPanel.Dock="Right" Content="Push" MinWidth="72" Height="32"

src/Explorer.App/GitChangesWindow.xaml.cs

@@ -12,10 +12,13 @@ public partial class GitChangesWindow : Window
         InitializeComponent();
         DataContext = vm;
         ViewModel = vm;
+        ModelessWindowClose.EnableEscape(this);
     }
 
     public GitChangesViewModel ViewModel { get; }
 
+    private void OnClose(object sender, RoutedEventArgs e) => Close();
+
     private async void OnRowDoubleClick(object sender, MouseButtonEventArgs e)
         => await ShowDiffAsync().ConfigureAwait(true);
 

src/Explorer.App/GitDiffWindow.xaml

@@ -9,7 +9,7 @@
         Background="{DynamicResource Bg}" Foreground="{DynamicResource Fg}">
   <DockPanel Margin="16">
     <Button DockPanel.Dock="Bottom" Content="Close" MinWidth="88" Height="32" HorizontalAlignment="Right"
-            IsCancel="True" Margin="0,12,0,0"/>
+            Click="OnClose" Margin="0,12,0,0"/>
     <TextBlock DockPanel.Dock="Top" Text="{Binding EmptyText}" Margin="0,0,0,8"
                Foreground="{DynamicResource FgMuted}" TextWrapping="Wrap"
                Visibility="{Binding ShowEmpty, Converter={StaticResource BoolVis}}"/>

src/Explorer.App/GitDiffWindow.xaml.cs

@@ -10,5 +10,8 @@ public partial class GitDiffWindow : Window
         InitializeComponent();
         DataContext = vm;
         Title = vm.Title;
+        ModelessWindowClose.EnableEscape(this);
     }
+
+    private void OnClose(object sender, RoutedEventArgs e) => Close();
 }

src/Explorer.App/HostActivityMonitorWindow.xaml

@@ -0,0 +1,130 @@
+<Window x:Class="Explorer.App.HostActivityMonitorWindow"
+        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:shell="clr-namespace:System.Windows.Shell;assembly=PresentationFramework"
+        Title="Host activity"
+        Icon="pack://application:,,,/Assets/explorer-workbench.ico"
+        Height="640" Width="960"
+        MinHeight="420" MinWidth="720"
+        WindowStartupLocation="CenterOwner"
+        WindowStyle="None"
+        ResizeMode="CanResize"
+        Background="{DynamicResource Bg}"
+        Foreground="{DynamicResource Fg}"
+        UseLayoutRounding="True"
+        SnapsToDevicePixels="True">
+  <shell:WindowChrome.WindowChrome>
+    <shell:WindowChrome CaptionHeight="40"
+                        ResizeBorderThickness="6"
+                        GlassFrameThickness="0"
+                        CornerRadius="0"
+                        UseAeroCaptionButtons="False"/>
+  </shell:WindowChrome.WindowChrome>
+  <DockPanel>
+    <Border DockPanel.Dock="Top" Height="40" Background="{DynamicResource Panel}"
+            BorderBrush="{DynamicResource Stroke}" BorderThickness="0,0,0,1"
+            MouseLeftButtonDown="OnTitleBarMouseDown">
+      <Grid>
+        <StackPanel Orientation="Horizontal" VerticalAlignment="Center" Margin="12,0,0,0" IsHitTestVisible="False">
+          <Image Width="20" Height="20" Margin="0,0,8,0" VerticalAlignment="Center"
+                 RenderOptions.BitmapScalingMode="HighQuality"
+                 Source="pack://application:,,,/Assets/explorer-workbench-20.png"/>
+          <TextBlock Text="Host activity" FontWeight="SemiBold" VerticalAlignment="Center"
+                     Foreground="{DynamicResource Fg}"/>
+        </StackPanel>
+        <StackPanel Orientation="Horizontal" HorizontalAlignment="Right">
+          <Button Style="{StaticResource CaptionButton}" Content="─" Click="OnMinimize" ToolTip="Minimize"/>
+          <Button x:Name="MaxRestoreButton" Style="{StaticResource CaptionButton}" Content="☐"
+                  Click="OnMaxRestore" ToolTip="Maximize"/>
+          <Button Style="{StaticResource CaptionCloseButton}" Content="✕" Click="OnClose" ToolTip="Close"/>
+        </StackPanel>
+      </Grid>
+    </Border>
+
+    <DockPanel Margin="14">
+      <DockPanel DockPanel.Dock="Bottom" Margin="0,10,0,0">
+        <Button DockPanel.Dock="Right" Content="Close" MinWidth="88" Height="30" Click="OnClose" Margin="8,0,0,0"/>
+        <Button DockPanel.Dock="Right" Content="Run maintenance now" MinWidth="140" Height="30"
+                Command="{Binding RunMaintenanceNowCommand}" Margin="8,0,0,0"/>
+        <Button DockPanel.Dock="Right" Content="Refresh" MinWidth="88" Height="30"
+                Command="{Binding RefreshCommand}" Margin="8,0,0,0"/>
+        <TextBlock VerticalAlignment="Center" Foreground="{DynamicResource FgMuted}">
+          <Run Text="{Binding Status, Mode=OneWay}"/>
+          <Run Text="  ·  "/>
+          <Run Text="{Binding IsLive, Mode=OneWay, StringFormat=Live: {0}}"/>
+        </TextBlock>
+      </DockPanel>
+
+      <TextBlock DockPanel.Dock="Top" Text="{Binding Summary}" FontWeight="SemiBold" FontSize="15"
+                 TextWrapping="Wrap" Margin="0,0,0,10"/>
+
+      <UniformGrid DockPanel.Dock="Top" Rows="2" Columns="2" Margin="0,0,0,10">
+        <Border BorderBrush="{DynamicResource Stroke}" BorderThickness="1" Padding="10" Margin="0,0,6,6">
+          <StackPanel>
+            <TextBlock Text="Maintenance" Foreground="{DynamicResource FgMuted}" FontSize="11"/>
+            <TextBlock Text="{Binding MaintenanceText}" TextWrapping="Wrap" Margin="0,4,0,0"/>
+          </StackPanel>
+        </Border>
+        <Border BorderBrush="{DynamicResource Stroke}" BorderThickness="1" Padding="10" Margin="6,0,0,6">
+          <StackPanel>
+            <TextBlock Text="Indexing" Foreground="{DynamicResource FgMuted}" FontSize="11"/>
+            <TextBlock Text="{Binding IndexingText}" TextWrapping="Wrap" Margin="0,4,0,0"/>
+          </StackPanel>
+        </Border>
+        <Border BorderBrush="{DynamicResource Stroke}" BorderThickness="1" Padding="10" Margin="0,6,6,0">
+          <StackPanel>
+            <TextBlock Text="Hashing" Foreground="{DynamicResource FgMuted}" FontSize="11"/>
+            <TextBlock Text="{Binding HashText}" TextWrapping="Wrap" Margin="0,4,0,0"/>
+          </StackPanel>
+        </Border>
+        <Border BorderBrush="{DynamicResource Stroke}" BorderThickness="1" Padding="10" Margin="6,6,0,0">
+          <StackPanel>
+            <TextBlock Text="Transfers" Foreground="{DynamicResource FgMuted}" FontSize="11"/>
+            <TextBlock Text="{Binding TransferText}" TextWrapping="Wrap" Margin="0,4,0,0"/>
+          </StackPanel>
+        </Border>
+      </UniformGrid>
+
+      <Grid>
+        <Grid.ColumnDefinitions>
+          <ColumnDefinition Width="280"/>
+          <ColumnDefinition Width="10"/>
+          <ColumnDefinition Width="*"/>
+        </Grid.ColumnDefinitions>
+        <DockPanel>
+          <TextBlock DockPanel.Dock="Top" Text="Current indexing jobs" FontWeight="SemiBold" Margin="0,0,0,6"/>
+          <ListView ItemsSource="{Binding Jobs}" BorderBrush="{DynamicResource Stroke}"
+                    ScrollViewer.VerticalScrollBarVisibility="Auto"
+                    ScrollViewer.HorizontalScrollBarVisibility="Disabled">
+            <ListView.ItemTemplate>
+              <DataTemplate>
+                <StackPanel Margin="0,2">
+                  <TextBlock Text="{Binding Title}" FontWeight="SemiBold"/>
+                  <TextBlock Text="{Binding Detail}" Foreground="{DynamicResource FgMuted}" TextTrimming="CharacterEllipsis"/>
+                  <TextBlock Text="{Binding Origin}" Foreground="{DynamicResource FgMuted}" FontSize="11"/>
+                </StackPanel>
+              </DataTemplate>
+            </ListView.ItemTemplate>
+          </ListView>
+        </DockPanel>
+        <DockPanel Grid.Column="2">
+          <TextBlock DockPanel.Dock="Top" Text="{Binding LogCaption}" FontWeight="SemiBold" Margin="0,0,0,6"/>
+          <ListView x:Name="EventList" ItemsSource="{Binding Events}" BorderBrush="{DynamicResource Stroke}"
+                    ScrollViewer.ScrollChanged="OnEventScrollChanged"
+                    ScrollViewer.VerticalScrollBarVisibility="Visible"
+                    ScrollViewer.HorizontalScrollBarVisibility="Auto"
+                    VirtualizingPanel.IsVirtualizing="True"
+                    VirtualizingPanel.VirtualizationMode="Recycling">
+            <ListView.View>
+              <GridView>
+                <GridViewColumn Header="Time" Width="70" DisplayMemberBinding="{Binding Time}"/>
+                <GridViewColumn Header="Area" Width="100" DisplayMemberBinding="{Binding Category}"/>
+                <GridViewColumn Header="Detail" Width="440" DisplayMemberBinding="{Binding Message}"/>
+              </GridView>
+            </ListView.View>
+          </ListView>
+        </DockPanel>
+      </Grid>
+    </DockPanel>
+  </DockPanel>
+</Window>

src/Explorer.App/HostActivityMonitorWindow.xaml.cs

@@ -0,0 +1,139 @@
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Input;
+using System.Windows.Media;
+using System.Windows.Threading;
+using Explorer.Presentation.ViewModels;
+
+namespace Explorer.App;
+
+public partial class HostActivityMonitorWindow : Window
+{
+    private bool _stickToEnd = true;
+    private bool _scrollQueued;
+    private ScrollViewer? _eventScroll;
+
+    public HostActivityMonitorWindow(HostActivityMonitorViewModel vm)
+    {
+        InitializeComponent();
+        DataContext = vm;
+        ViewModel = vm;
+        ModelessWindowClose.EnableEscape(this);
+        StateChanged += (_, _) => SyncMaxRestoreButton();
+        vm.EventsReplaced += OnEventsReplaced;
+        Closed += (_, _) =>
+        {
+            vm.EventsReplaced -= OnEventsReplaced;
+            vm.Dispose();
+        };
+        Loaded += (_, _) =>
+        {
+            SyncMaxRestoreButton();
+            _eventScroll = FindScrollViewer(EventList);
+            vm.Start();
+        };
+    }
+
+    public HostActivityMonitorViewModel ViewModel { get; }
+
+    private void OnClose(object sender, RoutedEventArgs e) => Close();
+
+    private void OnMinimize(object sender, RoutedEventArgs e) => WindowState = WindowState.Minimized;
+
+    private void OnMaxRestore(object sender, RoutedEventArgs e) => ToggleMaximized();
+
+    private void OnTitleBarMouseDown(object sender, MouseButtonEventArgs e)
+    {
+        if (e.ChangedButton != MouseButton.Left)
+        {
+            return;
+        }
+
+        if (e.ClickCount == 2)
+        {
+            ToggleMaximized();
+            return;
+        }
+
+        DragMove();
+    }
+
+    private void ToggleMaximized()
+    {
+        WindowState = WindowState == WindowState.Maximized ? WindowState.Normal : WindowState.Maximized;
+        SyncMaxRestoreButton();
+    }
+
+    private void SyncMaxRestoreButton()
+        => MaxRestoreButton.Content = WindowState == WindowState.Maximized ? "❐" : "☐";
+
+    private void OnEventScrollChanged(object sender, ScrollChangedEventArgs e)
+    {
+        if (e.OriginalSource is not ScrollViewer viewer)
+        {
+            return;
+        }
+
+        _eventScroll = viewer;
+        if (e.ExtentHeightChange != 0)
+        {
+            return;
+        }
+
+        // Only treat intentional user scroll as leaving the live tail.
+        if (e.VerticalChange == 0)
+        {
+            return;
+        }
+
+        _stickToEnd = viewer.VerticalOffset >= viewer.ScrollableHeight - 8;
+    }
+
+    private void OnEventsReplaced(object? sender, EventArgs e)
+    {
+        if (!_stickToEnd || _scrollQueued)
+        {
+            return;
+        }
+
+        _scrollQueued = true;
+        Dispatcher.BeginInvoke(() =>
+        {
+            _scrollQueued = false;
+            if (!_stickToEnd)
+            {
+                return;
+            }
+
+            _eventScroll ??= FindScrollViewer(EventList);
+            if (_eventScroll is not null)
+            {
+                _eventScroll.ScrollToEnd();
+            }
+            else if (EventList.Items.Count > 0)
+            {
+                EventList.ScrollIntoView(EventList.Items[^1]);
+            }
+        }, DispatcherPriority.Background);
+    }
+
+    private static ScrollViewer? FindScrollViewer(DependencyObject root)
+    {
+        if (root is ScrollViewer scroll)
+        {
+            return scroll;
+        }
+
+        for (var i = 0; i < VisualTreeHelper.GetChildrenCount(root); i++)
+        {
+            var child = VisualTreeHelper.GetChild(root, i);
+            var found = FindScrollViewer(child);
+            if (found is not null)
+            {
+                return found;
+            }
+        }
+
+        return null;
+    }
+}

src/Explorer.App/MainWindow.xaml

@@ -183,6 +183,9 @@
           <MenuItem Header="_Operation profiles…" Click="OnOperationProfiles"/>
         </MenuItem>
         <MenuItem Header="_Development">
+          <MenuItem Header="_Host activity…" Click="OnHostActivity"/>
+          <MenuItem Header="_Database…" Click="OnDatabase"/>
+          <Separator/>
           <MenuItem Header="View _changes…" Click="OnGitChanges"
                     IsEnabled="{Binding ShowGitActions}"/>
           <MenuItem Header="_Commit…" Click="OnGitCommit"
@@ -986,22 +989,55 @@
       </Border>
 
       <Border Grid.Column="2" Background="#99000000" Visibility="{Binding Duplicates.IsOpen, Converter={StaticResource BoolVis}}">
-        <Border Background="{DynamicResource Panel}" BorderBrush="{DynamicResource Stroke}" BorderThickness="1" Margin="48" Padding="16">
-          <DockPanel>
-            <DockPanel DockPanel.Dock="Top" Margin="0,0,0,8">
+        <Border Background="{DynamicResource Panel}" BorderBrush="{DynamicResource Stroke}" BorderThickness="1"
+                Margin="48" Padding="16" VerticalAlignment="Stretch" HorizontalAlignment="Stretch">
+          <Grid>
+            <Grid.RowDefinitions>
+              <RowDefinition Height="Auto"/>
+              <RowDefinition Height="Auto"/>
+              <RowDefinition Height="Auto"/>
+              <RowDefinition Height="Auto"/>
+              <RowDefinition Height="*"/>
+            </Grid.RowDefinitions>
+            <DockPanel Margin="0,0,0,8">
               <Button DockPanel.Dock="Right" Content="Close" Command="{Binding Duplicates.CloseCommand}"/>
               <TextBlock Text="Duplicates" FontSize="18" FontWeight="SemiBold" Foreground="{DynamicResource Fg}"/>
             </DockPanel>
-            <TextBlock DockPanel.Dock="Top" Text="{Binding Duplicates.Status}" Foreground="{DynamicResource Fg}" Margin="0,0,0,8" TextWrapping="Wrap"/>
-            <StackPanel DockPanel.Dock="Top" Orientation="Horizontal" Margin="0,0,0,8">
+            <TextBlock Grid.Row="1" Text="{Binding Duplicates.Status}" Foreground="{DynamicResource Fg}" Margin="0,0,0,8" TextWrapping="Wrap"/>
+            <StackPanel Grid.Row="2" Orientation="Horizontal" Margin="0,0,0,8">
               <CheckBox Content="Show intentional" IsChecked="{Binding Duplicates.ShowIntentional}" Margin="0,0,16,0"/>
               <CheckBox Content="Show hard links" IsChecked="{Binding Duplicates.ShowHardlinks}"/>
             </StackPanel>
-            <ProgressBar DockPanel.Dock="Top" Margin="0,0,0,8" IsIndeterminate="True"
+            <ProgressBar Grid.Row="3" Margin="0,0,0,8" IsIndeterminate="True"
                          Visibility="{Binding Duplicates.IsBusy, Converter={StaticResource BoolVis}}"/>
-            <ScrollViewer VerticalScrollBarVisibility="Auto">
-              <ItemsControl ItemsSource="{Binding Duplicates.Groups}">
-                <ItemsControl.ItemTemplate>
+            <ListBox Grid.Row="4"
+                     ItemsSource="{Binding Duplicates.Groups}"
+                     Background="Transparent"
+                     BorderThickness="0"
+                     Padding="0"
+                     HorizontalContentAlignment="Stretch"
+                     ScrollViewer.CanContentScroll="True"
+                     ScrollViewer.HorizontalScrollBarVisibility="Disabled"
+                     ScrollViewer.VerticalScrollBarVisibility="Visible"
+                     VirtualizingPanel.IsVirtualizing="True"
+                     VirtualizingPanel.VirtualizationMode="Recycling"
+                     VirtualizingPanel.ScrollUnit="Pixel">
+              <ListBox.ItemContainerStyle>
+                <Style TargetType="ListBoxItem">
+                  <Setter Property="HorizontalContentAlignment" Value="Stretch"/>
+                  <Setter Property="Padding" Value="0"/>
+                  <Setter Property="Margin" Value="0"/>
+                  <Setter Property="FocusVisualStyle" Value="{x:Null}"/>
+                  <Setter Property="Template">
+                    <Setter.Value>
+                      <ControlTemplate TargetType="ListBoxItem">
+                        <ContentPresenter HorizontalAlignment="Stretch"/>
+                      </ControlTemplate>
+                    </Setter.Value>
+                  </Setter>
+                </Style>
+              </ListBox.ItemContainerStyle>
+              <ListBox.ItemTemplate>
                 <DataTemplate>
                   <Border BorderBrush="{DynamicResource Stroke}" BorderThickness="0,0,0,1" Padding="0,10">
                     <DockPanel>
@@ -1016,15 +1052,8 @@
                                   CommandParameter="{Binding}"
                                   Visibility="{Binding CanMarkAccidental, Converter={StaticResource BoolVis}}"/>
                         </StackPanel>
-                          <TextBlock Foreground="{DynamicResource Fg}" FontWeight="SemiBold">
-                            <Run Text="{Binding ClassLabel, Mode=OneWay}"/>
-                            <Run Text=" · "/>
-                            <Run Text="{Binding SizeLabel, Mode=OneWay}"/>
-                            <Run Text=" · "/>
-                            <Run Text="{Binding Summary, Mode=OneWay}"/>
-                            <Run Text=" · "/>
-                            <Run Text="{Binding WastedLabel, Mode=OneWay}"/>
-                          </TextBlock>
+                        <TextBlock Text="{Binding Header, Mode=OneWay}" Foreground="{DynamicResource Fg}" FontWeight="SemiBold"
+                                   TextTrimming="CharacterEllipsis"/>
                       </DockPanel>
                       <ItemsControl ItemsSource="{Binding Files}">
                         <ItemsControl.ItemTemplate>
@@ -1042,10 +1071,9 @@
                     </DockPanel>
                   </Border>
                 </DataTemplate>
-                </ItemsControl.ItemTemplate>
-              </ItemsControl>
-            </ScrollViewer>
-          </DockPanel>
+              </ListBox.ItemTemplate>
+            </ListBox>
+          </Grid>
         </Border>
       </Border>
     </Grid>

src/Explorer.App/MainWindow.xaml.cs

@@ -18,11 +18,14 @@ public partial class MainWindow : Window
 {
     private DocumentationWindow? _docs;
     private GitChangesWindow? _gitChanges;
+    private HostActivityMonitorWindow? _hostActivity;
+    private DatabaseWindow? _database;
     private Point _dragStart;
     private bool _dragPending;
     private MouseButton _dragButton;
     private FolderItemViewModel? _dragItem;
     private ListView? _dragList;
+    private bool _draggingFromHere;
     private FolderItemViewModel[] _dragSelection = [];
     private bool _dragFromMultiSelect;
     private bool _syncingSelection;
@@ -661,7 +664,7 @@ public partial class MainWindow : Window
         }
 
         _suppressItemContextMenu = false;
-        _dragStart = e.GetPosition(null);
+        _dragStart = e.GetPosition(this);
         _dragPending = true;
         _dragButton = e.ChangedButton;
         _dragList = sender as ListView;
@@ -739,11 +742,12 @@ public partial class MainWindow : Window
                            && dest is not null
                            && NavigationTreeViewModel.PathsEqual(hover.FullPath, dest)
                            && !DragDropPolicy.IsInvalidTarget(files, dest)
+                           && !IsRedundantLeftDrop(files, dest)
             ? hover
             : null;
         SetListDropTarget(folderTarget);
         SetTreeDropTarget(null);
-        if (dest is null || DragDropPolicy.IsInvalidTarget(files, dest))
+        if (dest is null || DragDropPolicy.IsInvalidTarget(files, dest) || IsRedundantLeftDrop(files, dest))
         {
             e.Effects = DragDropEffects.None;
             e.Handled = true;
@@ -786,6 +790,11 @@ public partial class MainWindow : Window
             return;
         }
 
+        if (IsRedundantLeftDrop(files, dest))
+        {
+            return;
+        }
+
         await ApplyDropAsync(files, dest, ResolveDropAction(e, files, dest)).ConfigureAwait(true);
     }
 
@@ -863,9 +872,8 @@ public partial class MainWindow : Window
             return;
         }
 
-        var pos = e.GetPosition(null);
-        if (Math.Abs(pos.X - _dragStart.X) < SystemParameters.MinimumHorizontalDragDistance
-            && Math.Abs(pos.Y - _dragStart.Y) < SystemParameters.MinimumVerticalDragDistance)
+        var pos = e.GetPosition(this);
+        if (!DragMovedEnough(pos, DragDropPolicy.DragStartDistance))
         {
             return;
         }
@@ -887,11 +895,19 @@ public partial class MainWindow : Window
         _sourceRightDrag = _dragButton == MouseButton.Right;
         _suppressItemContextMenu = _sourceRightDrag;
         var data = new DataObject(DataFormats.FileDrop, paths.ToArray());
+        _draggingFromHere = true;
+        try
+        {
             DragDrop.DoDragDrop(this, data, DragDropEffects.Copy | DragDropEffects.Move | DragDropEffects.Link);
+        }
+        finally
+        {
+            _draggingFromHere = false;
             _sourceRightDrag = false;
             _incomingRightDrag = false;
             ClearDropTargets();
         }
+    }
 
     protected override void OnQueryContinueDrag(QueryContinueDragEventArgs e)
     {
@@ -1017,16 +1033,58 @@ public partial class MainWindow : Window
     private string? ResolveDropDirectory(ListView list, DragEventArgs e)
     {
         var item = HitTestFolderItem(list, e.GetPosition(list));
+        if (!_draggingFromHere)
+        {
             if (item is { IsDirectory: true })
             {
                 return item.FullPath;
             }
 
+            return CurrentListDirectory(list);
+        }
+
+        var pos = e.GetPosition(this);
+        if (item is { IsDirectory: true }
+            && DragMovedEnough(pos, FolderDropDistance(list)))
+        {
+            return item.FullPath;
+        }
+
+        if (!ReferenceEquals(list, _dragList)
+            && !DragMovedEnough(pos, DragDropPolicy.DropCrossViewDistance))
+        {
+            return null;
+        }
+
+        return CurrentListDirectory(list);
+    }
+
+    private string? CurrentListDirectory(ListView list)
+    {
         var tab = Vm.ActiveTab;
         var path = list.ItemsSource == tab.Right.Items ? tab.Right.CurrentPath : tab.Left.CurrentPath;
         return LocationRoots.IsVirtual(path) ? null : path;
     }
 
+    private double FolderDropDistance(ListView list)
+        => ReferenceEquals(list, _dragList)
+            ? DragDropPolicy.DropIntoItemDistance
+            : DragDropPolicy.DropCrossViewDistance;
+
+    private bool DragMovedEnough(Point current, double preferred)
+        => DragDropPolicy.ExceedsDistance(
+            current.X - _dragStart.X,
+            current.Y - _dragStart.Y,
+            Math.Max(preferred, SystemDragMinimum));
+
+    private static double SystemDragMinimum
+        => Math.Max(SystemParameters.MinimumHorizontalDragDistance, SystemParameters.MinimumVerticalDragDistance);
+
+    private bool IsRedundantLeftDrop(IReadOnlyList<string> files, string dest)
+        => !_sourceRightDrag
+           && !_incomingRightDrag
+           && DragDropPolicy.AllAlreadyInDirectory(files, dest);
+
     private static FolderItemViewModel? HitTestFolderItem(DependencyObject? origin, Point point)
     {
         if (origin is not Visual visual)
@@ -1178,6 +1236,11 @@ public partial class MainWindow : Window
             return;
         }
 
+        if (IsRedundantLeftDrop(files, dest))
+        {
+            return;
+        }
+
         await ApplyDropAsync(files, dest, ResolveDropAction(e, files, dest)).ConfigureAwait(true);
     }
 
@@ -1848,6 +1911,48 @@ public partial class MainWindow : Window
     private void OnAbout(object sender, RoutedEventArgs e)
         => new AboutWindow { Owner = this }.ShowDialog();
 
+    private void OnHostActivity(object sender, RoutedEventArgs e)
+    {
+        if (_hostActivity is { IsVisible: true })
+        {
+            _hostActivity.Activate();
+            return;
+        }
+
+        var vm = Vm.CreateHostActivityMonitorViewModel();
+        if (vm is null)
+        {
+            MessageBox.Show(this, "Host activity is unavailable until the background host is connected.",
+                "Explorer Workbench", MessageBoxButton.OK, MessageBoxImage.Information);
+            return;
+        }
+
+        _hostActivity = new HostActivityMonitorWindow(vm) { Owner = this };
+        _hostActivity.Closed += (_, _) => _hostActivity = null;
+        _hostActivity.Show();
+    }
+
+    private void OnDatabase(object sender, RoutedEventArgs e)
+    {
+        if (_database is { IsVisible: true })
+        {
+            _database.Activate();
+            return;
+        }
+
+        var vm = Vm.CreateDatabaseViewerViewModel();
+        if (vm is null)
+        {
+            MessageBox.Show(this, "Database tools are unavailable.",
+                "Explorer Workbench", MessageBoxButton.OK, MessageBoxImage.Information);
+            return;
+        }
+
+        _database = new DatabaseWindow(vm) { Owner = this };
+        _database.Closed += (_, _) => _database = null;
+        _database.Show();
+    }
+
     private async void OnGitChanges(object sender, RoutedEventArgs e)
     {
         if (_gitChanges is { IsVisible: true })

src/Explorer.App/ModelessWindowClose.cs

@@ -0,0 +1,23 @@
+using System.Windows;
+using System.Windows.Input;
+
+namespace Explorer.App;
+
+/// <summary>
+/// Close helpers for windows opened with <see cref="Window.Show"/>.
+/// <see cref="Button.IsCancel"/> sets <see cref="Window.DialogResult"/>, which throws on modeless windows.
+/// </summary>
+internal static class ModelessWindowClose
+{
+    public static void EnableEscape(Window window)
+        => window.PreviewKeyDown += (_, e) =>
+        {
+            if (e.Key != Key.Escape)
+            {
+                return;
+            }
+
+            window.Close();
+            e.Handled = true;
+        };
+}

src/Explorer.Application/BackgroundMaintenance.cs

@@ -23,10 +23,12 @@ public interface IIdleIndexWork
 public interface IIdleHashWork
 {
     bool IsPaused { get; }
+    string? CurrentPath { get; }
     void Pause();
     void Resume();
     void BeginUserRequested();
     Task<bool> HasPendingAsync(CancellationToken cancellationToken = default);
+    Task<long> CountPendingAsync(CancellationToken cancellationToken = default);
 }
 
 public interface IHistoryMaintenance

src/Explorer.Application/HostActivityLog.cs

@@ -0,0 +1,87 @@
+using Explorer.Contracts;
+
+namespace Explorer.Application;
+
+public interface IHostActivitySink
+{
+    void Record(string category, string message);
+    IReadOnlyList<HostActivityEvent> TakeRecent(int max = 120);
+}
+
+public sealed class NullHostActivitySink : IHostActivitySink
+{
+    public static NullHostActivitySink Instance { get; } = new();
+
+    public void Record(string category, string message)
+    {
+    }
+
+    public IReadOnlyList<HostActivityEvent> TakeRecent(int max = 120) => [];
+}
+
+/// <summary>Bounded ring of host activity lines for the live monitor. Cheap to write; snapshot is a copy.</summary>
+public sealed class HostActivityLog : IHostActivitySink
+{
+    private readonly object _gate = new();
+    private readonly HostActivityEvent[] _ring;
+    private int _next;
+    private int _count;
+    private string? _lastKey;
+    private DateTimeOffset _lastUtc;
+
+    public HostActivityLog(int capacity = 48)
+    {
+        _ring = new HostActivityEvent[Math.Clamp(capacity, 32, 200)];
+    }
+
+    public void Record(string category, string message)
+    {
+        if (string.IsNullOrWhiteSpace(message))
+        {
+            return;
+        }
+
+        var cat = string.IsNullOrWhiteSpace(category) ? "Host" : category.Trim();
+        var msg = message.Trim();
+        var key = cat + "\u001f" + msg;
+        var now = DateTimeOffset.UtcNow;
+        lock (_gate)
+        {
+            if (key == _lastKey && (now - _lastUtc) < TimeSpan.FromMilliseconds(750))
+            {
+                return;
+            }
+
+            _lastKey = key;
+            _lastUtc = now;
+            _ring[_next] = new HostActivityEvent { Utc = now, Category = cat, Message = msg };
+            _next = (_next + 1) % _ring.Length;
+            if (_count < _ring.Length)
+            {
+                _count++;
+            }
+        }
+    }
+
+    public IReadOnlyList<HostActivityEvent> TakeRecent(int max = 120)
+    {
+        max = Math.Clamp(max, 1, _ring.Length);
+        lock (_gate)
+        {
+            var take = Math.Min(max, _count);
+            if (take == 0)
+            {
+                return [];
+            }
+
+            var result = new HostActivityEvent[take];
+            var start = (_next - take + _ring.Length) % _ring.Length;
+            for (var i = 0; i < take; i++)
+            {
+                result[i] = _ring[(start + i) % _ring.Length];
+            }
+
+            return result;
+        }
+    }
+}

src/Explorer.Application/ISqliteDatabaseSession.cs

@@ -0,0 +1,39 @@
+namespace Explorer.Application;
+
+public interface ISqliteDatabaseSessionFactory
+{
+    ISqliteDatabaseSession Create();
+}
+
+public interface ISqliteDatabaseSession : IAsyncDisposable
+{
+    string? Path { get; }
+    bool IsOpen { get; }
+    bool CanWrite { get; }
+    string ModeLabel { get; }
+    Task OpenAsync(string path, bool preferWrite, CancellationToken cancellationToken = default);
+    Task CloseAsync();
+    Task<IReadOnlyList<string>> ListTablesAsync(CancellationToken cancellationToken = default);
+    Task<SqliteTablePage> ReadTableAsync(string table, int offset, int take, CancellationToken cancellationToken = default);
+    Task<SqliteQueryResult> ExecuteAsync(string sql, CancellationToken cancellationToken = default);
+    Task UpdateCellAsync(string table, long rowId, string column, object? value, CancellationToken cancellationToken = default);
+    Task DeleteRowAsync(string table, long rowId, CancellationToken cancellationToken = default);
+    Task InsertRowAsync(string table, IReadOnlyDictionary<string, object?> values, CancellationToken cancellationToken = default);
+}
+
+public sealed class SqliteTablePage
+{
+    public required IReadOnlyList<string> Columns { get; init; }
+    public required IReadOnlyList<IReadOnlyList<object?>> Rows { get; init; }
+    public long TotalRows { get; init; }
+    public int Offset { get; init; }
+}
+
+public sealed class SqliteQueryResult
+{
+    public bool IsQuery { get; init; }
+    public IReadOnlyList<string> Columns { get; init; } = [];
+    public IReadOnlyList<IReadOnlyList<object?>> Rows { get; init; } = [];
+    public int RecordsAffected { get; init; }
+    public string Message { get; init; } = "";
+}

src/Explorer.Application/IndexedPathPresence.cs

@@ -0,0 +1,116 @@
+using Explorer.Domain;
+
+namespace Explorer.Application;
+
+public static class IndexedPathPresence
+{
+    public static bool FileExists(string root, string pathRel)
+    {
+        if (string.IsNullOrWhiteSpace(root) || string.IsNullOrWhiteSpace(pathRel))
+        {
+            return false;
+        }
+
+        if (TryArchiveFile(pathRel, out var archiveRel))
+        {
+            return ExistsFile(PathRules.Combine(root, archiveRel));
+        }
+
+        return ExistsFile(PathRules.Combine(root, pathRel));
+    }
+
+    public static bool RootReachable(string root)
+        => !string.IsNullOrWhiteSpace(root) && ExistsDirectory(root);
+
+    public static bool DirectoryExists(string path) => ExistsDirectory(path);
+
+    public static string? HighestMissingPrefix(string root, string pathRel)
+    {
+        if (FileExists(root, pathRel))
+        {
+            return null;
+        }
+
+        if (TryArchiveFile(pathRel, out var archiveRel))
+        {
+            return archiveRel;
+        }
+
+        var rootNorm = PathRules.FromExtended(root).TrimEnd('\\');
+        var current = PathRules.FromExtended(PathRules.Combine(root, pathRel));
+        var missing = pathRel;
+        while (true)
+        {
+            var parent = PathRules.Parent(current);
+            if (string.IsNullOrEmpty(parent)
+                || parent.Equals(rootNorm, StringComparison.OrdinalIgnoreCase)
+                || parent.Equals(rootNorm + "\\", StringComparison.OrdinalIgnoreCase))
+            {
+                break;
+            }
+
+            if (ExistsDirectory(parent) || ExistsFile(parent))
+            {
+                break;
+            }
+
+            missing = PathRules.MakeRelative(root, parent);
+            current = parent;
+        }
+
+        return missing;
+    }
+
+    public static string ReconcilePath(string pathRel, string missingPrefix)
+    {
+        if (!missingPrefix.Equals(pathRel, StringComparison.OrdinalIgnoreCase))
+        {
+            return missingPrefix;
+        }
+
+        var slash = pathRel.LastIndexOf('\\');
+        return slash <= 0 ? "" : pathRel[..slash];
+    }
+
+    internal static bool TryArchiveFile(string pathRel, out string archiveRel)
+    {
+        archiveRel = "";
+        var parts = pathRel.Split('\\', StringSplitOptions.RemoveEmptyEntries);
+        var acc = new List<string>();
+        for (var i = 0; i < parts.Length; i++)
+        {
+            acc.Add(parts[i]);
+            if (i < parts.Length - 1 && ArchiveFormats.IsArchive(parts[i]))
+            {
+                archiveRel = string.Join('\\', acc);
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    private static bool ExistsFile(string path)
+    {
+        var normal = PathRules.FromExtended(path);
+        if (File.Exists(normal))
+        {
+            return true;
+        }
+
+        var ext = PathRules.ToExtended(normal);
+        return ext != normal && File.Exists(ext);
+    }
+
+    private static bool ExistsDirectory(string path)
+    {
+        var normal = PathRules.FromExtended(path);
+        if (Directory.Exists(normal))
+        {
+            return true;
+        }
+
+        var ext = PathRules.ToExtended(normal);
+        return ext != normal && Directory.Exists(ext);
+    }
+}

src/Explorer.Contracts/HostActivity.cs

@@ -0,0 +1,52 @@
+namespace Explorer.Contracts;
+
+public sealed class HostActivitySnapshot
+{
+    public DateTimeOffset Utc { get; init; } = DateTimeOffset.UtcNow;
+    public MaintenanceSnapshot Maintenance { get; init; } = MaintenanceSnapshot.Empty;
+    public bool IdleAllowed { get; init; }
+    public int IdleQueued { get; init; }
+    public bool HashPaused { get; init; }
+    public long HashPending { get; init; }
+    public string? HashCurrentPath { get; init; }
+    public bool TransfersPaused { get; init; }
+    public int TransfersActive { get; init; }
+    public int TransfersQueued { get; init; }
+    public string? TransferCurrentPath { get; init; }
+    public string? LastIndexPath { get; init; }
+    public long LastIndexFilesDone { get; init; }
+    public long LastIndexDirsDone { get; init; }
+    public string? LastIndexStatus { get; init; }
+    public IReadOnlyList<HostActivityJob> IndexingJobs { get; init; } = [];
+    public IReadOnlyList<HostActivityEvent> RecentEvents { get; init; } = [];
+}
+
+public sealed class HostActivityJob
+{
+    public long SourceId { get; init; }
+    public required string SourceName { get; init; }
+    public required string Kind { get; init; }
+    public required string Origin { get; init; }
+    public string? PathRel { get; init; }
+    public bool VerifyChildren { get; init; }
+}
+
+public sealed class HostActivityEvent
+{
+    public DateTimeOffset Utc { get; init; }
+    public required string Category { get; init; }
+    public required string Message { get; init; }
+}
+
+public interface IHostActivity
+{
+    Task<HostActivitySnapshot> GetSnapshotAsync(CancellationToken cancellationToken = default);
+}
+
+public sealed class NullHostActivity : IHostActivity
+{
+    public static NullHostActivity Instance { get; } = new();
+
+    public Task<HostActivitySnapshot> GetSnapshotAsync(CancellationToken cancellationToken = default)
+        => Task.FromResult(new HostActivitySnapshot());
+}

src/Explorer.Domain/Abstractions/IIndexStore.cs

@@ -160,6 +160,7 @@ public interface IHashStore
 {
     Task EnqueueSizeCollisionsAsync(long? sourceId, CancellationToken cancellationToken = default);
     Task<bool> HasPendingAsync(CancellationToken cancellationToken = default);
+    Task<long> CountPendingAsync(CancellationToken cancellationToken = default);
     Task<IReadOnlyList<HashWorkItem>> DequeueAsync(int take, CancellationToken cancellationToken = default);
     Task CompletePartialAsync(long entryId, byte[] hash, CancellationToken cancellationToken = default);
     Task CompleteFullAsync(long entryId, byte[] hash, CancellationToken cancellationToken = default);
@@ -168,6 +169,10 @@ public interface IHashStore
     Task MarkSkippedAsync(long entryId, CancellationToken cancellationToken = default);
     Task<bool> HasPartialCollisionAsync(long entryId, long sizeBytes, CancellationToken cancellationToken = default);
     Task<IReadOnlyList<DuplicateGroup>> GetDuplicateGroupsAsync(long? sourceId, string? pathPrefix, int take, CancellationToken cancellationToken = default);
+    Task<IReadOnlyList<byte[]>> GetDuplicateHashesAsync(long? sourceId, string? pathPrefix, int take, CancellationToken cancellationToken = default);
+    Task<IReadOnlyList<DuplicateGroup>> GetDuplicateGroupsByHashesAsync(
+        IReadOnlyList<byte[]> hashes,
+        CancellationToken cancellationToken = default);
 }
 
 public interface IFileRelationStore

src/Explorer.Domain/DragDropPolicy.cs

@@ -54,4 +54,46 @@ public static class DragDropPolicy
 
         return false;
     }
+
+    /// <summary>
+    /// Windows SM_CXDRAG is typically 4 DIP — enough to turn a click into a drag.
+    /// A real drag is still immediate; this only ignores click jitter.
+    /// </summary>
+    public const double DragStartDistance = 16;
+
+    /// <summary>Dropping into a neighboring folder row should need more than a row-edge slip.</summary>
+    public const double DropIntoItemDistance = 28;
+
+    /// <summary>Crossing into the other pane or the tree should not happen at the splitter.</summary>
+    public const double DropCrossViewDistance = 36;
+
+    public static bool ExceedsDistance(double deltaX, double deltaY, double minimum)
+    {
+        var threshold = Math.Max(minimum, 0);
+        return (deltaX * deltaX) + (deltaY * deltaY) >= threshold * threshold;
+    }
+
+    public static bool AllAlreadyInDirectory(IReadOnlyList<string> sources, string destinationDirectory)
+    {
+        if (sources.Count == 0 || string.IsNullOrWhiteSpace(destinationDirectory))
+        {
+            return false;
+        }
+
+        var dest = NormalizeDirectory(destinationDirectory);
+        foreach (var source in sources)
+        {
+            var src = PathRules.FromExtended(source).TrimEnd('\\');
+            var parent = Path.GetDirectoryName(src);
+            if (parent is null || !NormalizeDirectory(parent).Equals(dest, StringComparison.OrdinalIgnoreCase))
+            {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    private static string NormalizeDirectory(string path)
+        => PathRules.FromExtended(path).TrimEnd('\\');
 }

src/Explorer.Hosting.Client/ExplorerHostClientServices.cs

@@ -36,6 +36,15 @@ public static class ExplorerHostClientServices
             services.AddSingleton(connection);
         }
 
+        if (workbench is IHostActivity activity)
+        {
+            services.AddSingleton(activity);
+        }
+        else
+        {
+            services.TryAddSingleton<IHostActivity>(_ => NullHostActivity.Instance);
+        }
+
         services.AddExplorerClientRuntime();
         return services;
     }
@@ -54,6 +63,7 @@ public static class ExplorerHostClientServices
             var logger = sp.GetRequiredService<ILogger<SqliteIndexStore>>();
             return new SqliteIndexStore(env.DatabasePath, logger, readOnly: true);
         });
+        services.AddSingleton<ISqliteDatabaseSessionFactory, SqliteDatabaseSessionFactory>();
         services.AddSingleton<IHydrationGuard, HydrationGuard>();
         services.AddSingleton<IArchiveExecutor, SevenZipArchiveExecutor>();
         services.AddSingleton<IMediaConversionProvider, FfmpegConversionExecutor>();

src/Explorer.Hosting.Client/Ipc/WorkbenchPipeClient.cs

@@ -8,7 +8,7 @@ using Explorer.Plugin.Abstractions;
 
 namespace Explorer.Hosting.Ipc;
 
-public sealed class WorkbenchPipeClient : IWorkbenchHost, ICloudOverlay, IHostConnection, IBackgroundMaintenance, IAsyncDisposable
+public sealed class WorkbenchPipeClient : IWorkbenchHost, ICloudOverlay, IHostConnection, IBackgroundMaintenance, IHostActivity, IAsyncDisposable
 {
     private NamedPipeClientStream _pipe;
     private StreamWriter _writer;
@@ -51,6 +51,18 @@ public sealed class WorkbenchPipeClient : IWorkbenchHost, ICloudOverlay, IHostCo
 
     public void RunNow() => Call("Maintenance.RunNow");
 
+    public async Task<HostActivitySnapshot> GetSnapshotAsync(CancellationToken cancellationToken = default)
+    {
+        var reply = await CallAsync("Host.ActivitySnapshot", cancellationToken).ConfigureAwait(false);
+        if (string.IsNullOrWhiteSpace(reply.Payload))
+        {
+            return new HostActivitySnapshot { Maintenance = _maintenance };
+        }
+
+        return JsonSerializer.Deserialize<HostActivitySnapshot>(reply.Payload, WorkbenchIpc.Json)
+               ?? new HostActivitySnapshot { Maintenance = _maintenance };
+    }
+
     public static async Task<WorkbenchPipeClient> ConnectAsync(
         WorkbenchIpcOptions options,
         TimeSpan timeout,

src/Explorer.Hosting/BackgroundMaintenanceCoordinator.cs

@@ -17,6 +17,7 @@ public sealed class BackgroundMaintenanceCoordinator : BackgroundService, IBackg
     private readonly IHistoryMaintenance _history;
     private readonly IIndexStore _store;
     private readonly IVolumeService _volumes;
+    private readonly IHostActivitySink _activity;
     private readonly ILogger<BackgroundMaintenanceCoordinator> _logger;
     private readonly HashSet<long> _collisionEnqueued = [];
     private readonly HashSet<long> _idleScanQueued = [];
@@ -42,7 +43,8 @@ public sealed class BackgroundMaintenanceCoordinator : BackgroundService, IBackg
         IHistoryMaintenance history,
         IIndexStore store,
         IVolumeService volumes,
-        ILogger<BackgroundMaintenanceCoordinator> logger)
+        ILogger<BackgroundMaintenanceCoordinator> logger,
+        IHostActivitySink? activity = null)
     {
         _idle = idle;
         _power = power;
@@ -54,6 +56,7 @@ public sealed class BackgroundMaintenanceCoordinator : BackgroundService, IBackg
         _store = store;
         _volumes = volumes;
         _logger = logger;
+        _activity = activity ?? NullHostActivitySink.Instance;
     }
 
     public event EventHandler<MaintenanceSnapshot>? Changed;
@@ -149,10 +152,12 @@ public sealed class BackgroundMaintenanceCoordinator : BackgroundService, IBackg
                 _hash.Pause();
             }
 
-            _workMessage = _indexing.HasIdleWork
-                ? (_workMessage ?? "Scanning")
-                : "Idle maintenance";
-            Publish(decision, _workMessage);
+            // Keep the idle-maintenance caption only while idle work is still queued/running.
+            // Watcher/user jobs must not keep showing a stale "checking External" line.
+            var busyMessage = _indexing.HasIdleWork
+                ? (_workMessage ?? "Idle maintenance")
+                : "";
+            Publish(decision, busyMessage);
             return;
         }
 
@@ -167,7 +172,8 @@ public sealed class BackgroundMaintenanceCoordinator : BackgroundService, IBackg
 
             _idleVerified.Add(verify.Id);
             _indexing.EnqueueIdleVerify(verify.Id, "");
-            _runNow = false;
+            // Keep _runNow until the whole RunNow session finishes so user activity
+            // does not cancel the work that was just started via the button.
             _workMessage = "Idle maintenance · checking " + verify.DisplayName;
             _logger.LogDebug("maintenance started verify {Source}", verify.DisplayName);
             Publish(decision, _workMessage);
@@ -184,7 +190,6 @@ public sealed class BackgroundMaintenanceCoordinator : BackgroundService, IBackg
 
             _idleScanQueued.Add(scan.Id);
             _indexing.EnqueueIdleFullScan(scan.Id);
-            _runNow = false;
             _workMessage = "Scanning " + scan.DisplayName;
             _logger.LogDebug("maintenance started scan {Source}", scan.DisplayName);
             Publish(decision, _workMessage);
@@ -194,16 +199,14 @@ public sealed class BackgroundMaintenanceCoordinator : BackgroundService, IBackg
         _hash.Resume();
         if (hashPending)
         {
-            _runNow = false;
-            _workMessage = "Idle maintenance";
+            _workMessage = "Idle maintenance · hashing";
             Publish(decision, _workMessage);
             return;
         }
 
         if (await _history.TryCaptureAsync(cancellationToken).ConfigureAwait(false))
         {
-            _runNow = false;
-            _workMessage = "Idle maintenance";
+            _workMessage = "Idle maintenance · history";
             _logger.LogDebug("maintenance completed (history)");
             Publish(decision, _workMessage);
             return;
@@ -214,7 +217,7 @@ public sealed class BackgroundMaintenanceCoordinator : BackgroundService, IBackg
         {
             _collisionEnqueued.Add(hashSource.Id);
             await _store.Hashes.EnqueueSizeCollisionsAsync(hashSource.Id, cancellationToken).ConfigureAwait(false);
-            _workMessage = "Idle maintenance";
+            _workMessage = "Idle maintenance · hash queue";
             Publish(decision, _workMessage);
             return;
         }
@@ -261,6 +264,11 @@ public sealed class BackgroundMaintenanceCoordinator : BackgroundService, IBackg
             _snapshot = snapshot;
         }
 
+        if (!string.IsNullOrWhiteSpace(message))
+        {
+            _activity.Record("Maintenance", message);
+        }
+
         Changed?.Invoke(this, snapshot);
     }
 }

src/Explorer.Hosting/ExplorerHostServices.cs

@@ -84,6 +84,7 @@ public static class ExplorerHostServices
 
     public static IServiceCollection AddExplorerWorkers(this IServiceCollection services)
     {
+        services.AddSingleton<IHostActivitySink, HostActivityLog>();
         services.AddSingleton<IndexingCoordinator>();
         services.AddSingleton<DirectoryWatcherHub>();
         services.AddSingleton<IOperationExecutor, NativeFileOperationExecutor>();

src/Explorer.Hosting/Ipc/WorkbenchPipeServer.cs

@@ -317,6 +317,11 @@ public sealed class WorkbenchPipeServer : BackgroundService
                     reply.Payload = JsonSerializer.Serialize(snap, WorkbenchIpc.Json);
                     return reply;
                 }
+                case "Host.ActivitySnapshot":
+                {
+                    reply.Payload = JsonSerializer.Serialize(await BuildActivitySnapshotAsync().ConfigureAwait(false), WorkbenchIpc.Json);
+                    return reply;
+                }
                 case "Host.Shutdown":
                     await RequestShutdownAsync().ConfigureAwait(false);
                     return reply;
@@ -536,6 +541,40 @@ public sealed class WorkbenchPipeServer : BackgroundService
         }
     }
 
+    private async Task<HostActivitySnapshot> BuildActivitySnapshotAsync()
+    {
+        var maintenance = _services.GetService<IBackgroundMaintenance>()?.Snapshot ?? MaintenanceSnapshot.Empty;
+        var indexing = _services.GetService<Indexing.IndexingCoordinator>();
+        var hash = _services.GetService<IIdleHashWork>();
+        var transfers = _services.GetService<ITransferHost>();
+        var activity = _services.GetService<IHostActivitySink>();
+        var jobs = transfers?.Snapshot() ?? [];
+        var active = jobs.Count(j => j.Status is TransferStatus.Running or TransferStatus.Cancelling);
+        var queued = jobs.Count(j => j.Status is TransferStatus.Waiting or TransferStatus.Paused);
+        var running = jobs.FirstOrDefault(j => j.Status is TransferStatus.Running or TransferStatus.Cancelling);
+        var last = indexing?.LastProgress;
+        return new HostActivitySnapshot
+        {
+            Utc = DateTimeOffset.UtcNow,
+            Maintenance = maintenance,
+            IdleAllowed = indexing?.IdleAllowed ?? false,
+            IdleQueued = indexing?.IdleQueued ?? 0,
+            HashPaused = hash?.IsPaused ?? true,
+            HashPending = hash is null ? 0 : await hash.CountPendingAsync().ConfigureAwait(false),
+            HashCurrentPath = hash?.CurrentPath,
+            TransfersPaused = transfers?.IsPaused ?? false,
+            TransfersActive = active,
+            TransfersQueued = queued,
+            TransferCurrentPath = running?.CurrentPath ?? running?.SourcePath,
+            LastIndexPath = last?.CurrentPath,
+            LastIndexFilesDone = last?.FilesSeen ?? 0,
+            LastIndexDirsDone = last?.DirsSeen ?? 0,
+            LastIndexStatus = last?.Status.ToString(),
+            IndexingJobs = indexing?.GetRunningJobs() ?? [],
+            RecentEvents = activity?.TakeRecent(40) ?? []
+        };
+    }
+
     private static T Read<T>(string? payload)
         => JsonSerializer.Deserialize<T>(payload ?? "null", WorkbenchIpc.Json)
            ?? throw new InvalidOperationException("Missing payload for " + typeof(T).Name);

src/Explorer.Indexing/FolderReconciler.cs

@@ -26,7 +26,7 @@ public sealed class FolderReconciler
         _preferences = preferences;
     }
 
-    public Task ReconcileAsync(Source source, string pathRel, CancellationToken cancellationToken)
+    public Task<bool> ReconcileAsync(Source source, string pathRel, CancellationToken cancellationToken)
         => ReconcileAsync(source, pathRel, cancellationToken, verifyChildren: false);
 
     public Task<bool> ReconcileAsync(
@@ -74,11 +74,25 @@ public sealed class FolderReconciler
             return false;
         }
 
-        if (!Directory.Exists(full) || LocationClassifier.IsRecycleBinName(parent.Name))
+        if (LocationClassifier.IsRecycleBinName(parent.Name))
         {
             return false;
         }
 
+        if (!IndexedPathPresence.DirectoryExists(full))
+        {
+            if (string.IsNullOrEmpty(pathRel))
+            {
+                return false;
+            }
+
+            var gone = DateTimeOffset.UtcNow;
+            await _store.Entries.TombstoneByPathPrefixAsync(source.Id, parent.PathRel, gone, cancellationToken)
+                .ConfigureAwait(false);
+            await _store.Entries.TombstoneAsync(parent.Id, gone, cancellationToken).ConfigureAwait(false);
+            return true;
+        }
+
         var live = await _providers.EnrichAsync(_enumerator.EnumerateChildrenSafe(full, out _), cancellationToken)
             .ConfigureAwait(false);
         var indexed = await _store.Entries.GetChildrenAsync(source.Id, parent.Id, EntryStatus.Present, cancellationToken)

src/Explorer.Indexing/IndexingCoordinator.cs

@@ -16,12 +16,15 @@ public sealed class IndexingCoordinator : BackgroundService, IIndexingHost, IIdl
     private readonly UsnChangeApplier _usn;
     private readonly IUsnJournal _journal;
     private readonly IVolumeService _volumes;
+    private readonly IHostActivitySink _activity;
     private readonly ILogger<IndexingCoordinator> _logger;
     private readonly Channel<IndexWork> _work = Channel.CreateUnbounded<IndexWork>();
     private readonly Dictionary<long, RunningWork> _running = new();
     private readonly object _gate = new();
     private volatile bool _idleAllowed;
     private int _idleQueued;
+    private ScanProgress? _lastProgress;
+    private DateTimeOffset _lastActivityLogUtc;
 
     public event EventHandler<ScanProgress>? ProgressChanged;
 
@@ -32,7 +35,8 @@ public sealed class IndexingCoordinator : BackgroundService, IIndexingHost, IIdl
         UsnChangeApplier usn,
         IUsnJournal journal,
         IVolumeService volumes,
-        ILogger<IndexingCoordinator> logger)
+        ILogger<IndexingCoordinator> logger,
+        IHostActivitySink? activity = null)
     {
         _store = store;
         _scanner = scanner;
@@ -41,6 +45,7 @@ public sealed class IndexingCoordinator : BackgroundService, IIndexingHost, IIdl
         _journal = journal;
         _volumes = volumes;
         _logger = logger;
+        _activity = activity ?? NullHostActivitySink.Instance;
     }
 
     public bool IsBusy
@@ -65,6 +70,36 @@ public sealed class IndexingCoordinator : BackgroundService, IIndexingHost, IIdl
         }
     }
 
+    public int IdleQueued
+    {
+        get { lock (_gate) { return _idleQueued; } }
+    }
+
+    public bool IdleAllowed => _idleAllowed;
+
+    public ScanProgress? LastProgress
+    {
+        get { lock (_gate) { return _lastProgress; } }
+    }
+
+    public IReadOnlyList<HostActivityJob> GetRunningJobs()
+    {
+        lock (_gate)
+        {
+            return _running.Values
+                .Select(w => new HostActivityJob
+                {
+                    SourceId = w.SourceId,
+                    SourceName = w.SourceName,
+                    Kind = w.Kind.ToString(),
+                    Origin = w.Origin.ToString(),
+                    PathRel = w.PathRel,
+                    VerifyChildren = w.VerifyChildren
+                })
+                .ToList();
+        }
+    }
+
     public void SetIdleAllowed(bool allowed)
     {
         _idleAllowed = allowed;
@@ -176,9 +211,22 @@ public sealed class IndexingCoordinator : BackgroundService, IIndexingHost, IIdl
         using var linked = CancellationTokenSource.CreateLinkedTokenSource(stoppingToken);
         lock (_gate)
         {
-            _running[item.SourceId] = new RunningWork(linked, item.Origin);
+            _running[item.SourceId] = new RunningWork(
+                linked,
+                item.Origin,
+                item.Kind,
+                item.SourceId,
+                source.DisplayName,
+                item.PathRel,
+                item.VerifyChildren);
         }
 
+        _activity.Record(
+            "Indexing",
+            item.Kind + " · " + source.DisplayName
+            + (string.IsNullOrEmpty(item.PathRel) ? "" : " · " + item.PathRel)
+            + " (" + item.Origin + ")");
+
         try
         {
             switch (item.Kind)
@@ -189,7 +237,16 @@ public sealed class IndexingCoordinator : BackgroundService, IIndexingHost, IIdl
                         source,
                         item.Kind == WorkKind.Full ? ScanKind.Full : ScanKind.Folder,
                         item.PathRel,
-                        new Progress<ScanProgress>(p => ProgressChanged?.Invoke(this, p)),
+                        new Progress<ScanProgress>(p =>
+                        {
+                            lock (_gate)
+                            {
+                                _lastProgress = p;
+                            }
+
+                            NoteProgress(p);
+                            ProgressChanged?.Invoke(this, p);
+                        }),
                         linked.Token).ConfigureAwait(false);
                     EnqueueUsn(source.Id);
                     break;
@@ -204,13 +261,19 @@ public sealed class IndexingCoordinator : BackgroundService, IIndexingHost, IIdl
                             var full = source.LastRootPath is null
                                 ? item.PathRel
                                 : PathRules.Combine(source.LastRootPath, item.PathRel);
-                            ProgressChanged?.Invoke(this, new ScanProgress
+                            var done = new ScanProgress
                             {
                                 SourceId = source.Id,
                                 CurrentPath = full,
                                 Status = ScanJobStatus.Done,
                                 IndexRefresh = true
-                            });
+                            };
+                            lock (_gate)
+                            {
+                                _lastProgress = done;
+                            }
+
+                            ProgressChanged?.Invoke(this, done);
                         }
                     }
 
@@ -229,6 +292,29 @@ public sealed class IndexingCoordinator : BackgroundService, IIndexingHost, IIdl
         }
     }
 
+    private void NoteProgress(ScanProgress progress)
+    {
+        if (progress.IndexRefresh || string.IsNullOrWhiteSpace(progress.CurrentPath))
+        {
+            return;
+        }
+
+        var now = DateTimeOffset.UtcNow;
+        lock (_gate)
+        {
+            if ((now - _lastActivityLogUtc) < TimeSpan.FromSeconds(1.5))
+            {
+                return;
+            }
+
+            _lastActivityLogUtc = now;
+        }
+
+        _activity.Record(
+            "Indexing",
+            progress.FilesSeen + " files · " + progress.DirsSeen + " dirs · " + progress.CurrentPath);
+    }
+
     private async Task PeriodicAsync(CancellationToken stoppingToken)
     {
         using var timer = new PeriodicTimer(TimeSpan.FromSeconds(30));
@@ -256,5 +342,12 @@ public sealed class IndexingCoordinator : BackgroundService, IIndexingHost, IIdl
         IndexWorkOrigin Origin,
         bool VerifyChildren = false);
 
-    private sealed record RunningWork(CancellationTokenSource Cts, IndexWorkOrigin Origin);
+    private sealed record RunningWork(
+        CancellationTokenSource Cts,
+        IndexWorkOrigin Origin,
+        WorkKind Kind,
+        long SourceId,
+        string SourceName,
+        string? PathRel,
+        bool VerifyChildren);
 }

src/Explorer.Presentation/ViewModels/DatabaseViewerViewModel.cs

@@ -0,0 +1,327 @@
+using System.Collections.ObjectModel;
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
+using Explorer.Application;
+using Explorer.Domain.Abstractions;
+
+namespace Explorer.Presentation.ViewModels;
+
+public sealed partial class DatabaseViewerViewModel : ObservableObject, IAsyncDisposable
+{
+    private readonly ISqliteDatabaseSessionFactory _factory;
+    private readonly IAppEnvironment _environment;
+    private ISqliteDatabaseSession? _session;
+    private const int PageSize = 100;
+
+    [ObservableProperty] private string _pathLabel = "No database open";
+    [ObservableProperty] private string _modeLabel = "Closed";
+    [ObservableProperty] private string _status = "";
+    [ObservableProperty] private string? _selectedTable;
+    [ObservableProperty] private string _sql = "SELECT name, type FROM sqlite_master ORDER BY name;";
+    [ObservableProperty] private bool _canWrite;
+    [ObservableProperty] private bool _isOpen;
+    [ObservableProperty] private int _pageOffset;
+    [ObservableProperty] private long _totalRows;
+    [ObservableProperty] private string _pageLabel = "";
+    [ObservableProperty] private SqliteGridRow? _selectedRow;
+
+    public DatabaseViewerViewModel(ISqliteDatabaseSessionFactory factory, IAppEnvironment environment)
+    {
+        _factory = factory;
+        _environment = environment;
+        Tables = [];
+        Columns = [];
+        Rows = [];
+    }
+
+    public ObservableCollection<string> Tables { get; }
+    public ObservableCollection<string> Columns { get; }
+    public ObservableCollection<SqliteGridRow> Rows { get; }
+    public string DefaultIndexPath => _environment.DatabasePath;
+
+    public event EventHandler? GridChanged;
+
+    public async Task OpenIndexAsync(bool preferWrite = false)
+        => await OpenPathAsync(_environment.DatabasePath, preferWrite).ConfigureAwait(true);
+
+    public async Task OpenPathAsync(string path, bool preferWrite)
+    {
+        Status = "Opening…";
+        try
+        {
+            _session ??= _factory.Create();
+            await _session.OpenAsync(path, preferWrite).ConfigureAwait(true);
+            PathLabel = _session.Path ?? path;
+            ModeLabel = _session.ModeLabel;
+            CanWrite = _session.CanWrite;
+            IsOpen = true;
+            await ReloadTablesAsync().ConfigureAwait(true);
+            Status = ModeLabel;
+        }
+        catch (Exception ex)
+        {
+            Status = "Open failed: " + ex.Message;
+            IsOpen = false;
+        }
+    }
+
+    [RelayCommand]
+    private Task OpenWorkbenchIndexAsync() => OpenIndexAsync(preferWrite: false);
+
+    [RelayCommand]
+    private async Task CloseDatabaseAsync()
+    {
+        if (_session is not null)
+        {
+            await _session.CloseAsync().ConfigureAwait(true);
+        }
+
+        Tables.Clear();
+        ClearGrid();
+        SelectedTable = null;
+        IsOpen = false;
+        CanWrite = false;
+        PathLabel = "No database open";
+        ModeLabel = "Closed";
+        Status = "Closed";
+    }
+
+    [RelayCommand]
+    private async Task RefreshTablesAsync()
+    {
+        if (_session is not { IsOpen: true })
+        {
+            return;
+        }
+
+        await ReloadTablesAsync().ConfigureAwait(true);
+    }
+
+    [RelayCommand]
+    private Task LoadSelectedTableAsync() => LoadTablePageAsync(0);
+
+    [RelayCommand]
+    private Task NextPageAsync() => LoadTablePageAsync(PageOffset + PageSize);
+
+    [RelayCommand]
+    private Task PrevPageAsync() => LoadTablePageAsync(Math.Max(0, PageOffset - PageSize));
+
+    [RelayCommand]
+    private async Task RunSqlAsync()
+    {
+        if (_session is not { IsOpen: true })
+        {
+            return;
+        }
+
+        try
+        {
+            var result = await _session.ExecuteAsync(Sql).ConfigureAwait(true);
+            if (result.IsQuery)
+            {
+                ApplyGrid(result.Columns, result.Rows, result.Rows.Count, 0);
+            }
+            else
+            {
+                Status = result.Message;
+                if (!string.IsNullOrWhiteSpace(SelectedTable))
+                {
+                    await LoadTablePageAsync(PageOffset).ConfigureAwait(true);
+                }
+            }
+
+            if (result.IsQuery)
+            {
+                Status = result.Message;
+            }
+        }
+        catch (Exception ex)
+        {
+            Status = "SQL failed: " + ex.Message;
+        }
+    }
+
+    [RelayCommand]
+    private async Task DeleteSelectedRowAsync()
+    {
+        if (_session is not { IsOpen: true, CanWrite: true }
+            || string.IsNullOrWhiteSpace(SelectedTable)
+            || SelectedRow is null
+            || SelectedRow.RowId is null)
+        {
+            Status = "Select a table row with a rowid to delete.";
+            return;
+        }
+
+        try
+        {
+            await _session.DeleteRowAsync(SelectedTable, SelectedRow.RowId.Value).ConfigureAwait(true);
+            Status = "Row deleted.";
+            await LoadTablePageAsync(PageOffset).ConfigureAwait(true);
+        }
+        catch (Exception ex)
+        {
+            Status = "Delete failed: " + ex.Message;
+        }
+    }
+
+    public async Task UpdateSelectedCellAsync(string column, object? value)
+    {
+        if (_session is not { IsOpen: true, CanWrite: true }
+            || string.IsNullOrWhiteSpace(SelectedTable)
+            || SelectedRow?.RowId is null)
+        {
+            throw new InvalidOperationException("Select a writable row first.");
+        }
+
+        await _session.UpdateCellAsync(SelectedTable, SelectedRow.RowId.Value, column, value).ConfigureAwait(true);
+        Status = "Cell updated.";
+        await LoadTablePageAsync(PageOffset).ConfigureAwait(true);
+    }
+
+    public async Task InsertRowAsync(IReadOnlyDictionary<string, object?> values)
+    {
+        if (_session is not { IsOpen: true, CanWrite: true } || string.IsNullOrWhiteSpace(SelectedTable))
+        {
+            throw new InvalidOperationException("Open a writable table first.");
+        }
+
+        await _session.InsertRowAsync(SelectedTable, values).ConfigureAwait(true);
+        Status = "Row inserted.";
+        await LoadTablePageAsync(PageOffset).ConfigureAwait(true);
+    }
+
+    public IReadOnlyList<string> EditableColumns()
+        => Columns.Where(c => !c.Equals("_rowid_", StringComparison.OrdinalIgnoreCase)).ToList();
+
+    partial void OnSelectedTableChanged(string? value)
+    {
+        if (!string.IsNullOrWhiteSpace(value))
+        {
+            _ = LoadTablePageAsync(0);
+        }
+    }
+
+    private async Task ReloadTablesAsync()
+    {
+        if (_session is not { IsOpen: true })
+        {
+            return;
+        }
+
+        var tables = await _session.ListTablesAsync().ConfigureAwait(true);
+        Tables.Clear();
+        foreach (var table in tables)
+        {
+            Tables.Add(table);
+        }
+
+        if (SelectedTable is null || !Tables.Contains(SelectedTable))
+        {
+            SelectedTable = Tables.FirstOrDefault();
+        }
+    }
+
+    private async Task LoadTablePageAsync(int offset)
+    {
+        if (_session is not { IsOpen: true } || string.IsNullOrWhiteSpace(SelectedTable))
+        {
+            return;
+        }
+
+        try
+        {
+            var page = await _session.ReadTableAsync(SelectedTable, offset, PageSize).ConfigureAwait(true);
+            PageOffset = page.Offset;
+            TotalRows = page.TotalRows;
+            PageLabel = page.TotalRows == 0
+                ? "0 rows"
+                : $"{page.Offset + 1}–{page.Offset + page.Rows.Count} of {page.TotalRows}";
+            ApplyGrid(page.Columns, page.Rows, page.TotalRows, page.Offset);
+            Status = "Table " + SelectedTable + " · " + PageLabel;
+        }
+        catch (Exception ex)
+        {
+            Status = "Load failed: " + ex.Message;
+        }
+    }
+
+    private void ApplyGrid(
+        IReadOnlyList<string> columns,
+        IReadOnlyList<IReadOnlyList<object?>> rows,
+        long total,
+        int offset)
+    {
+        Columns.Clear();
+        foreach (var column in columns)
+        {
+            Columns.Add(column);
+        }
+
+        Rows.Clear();
+        var rowIdIndex = -1;
+        for (var i = 0; i < columns.Count; i++)
+        {
+            if (columns[i].Equals("_rowid_", StringComparison.OrdinalIgnoreCase))
+            {
+                rowIdIndex = i;
+                break;
+            }
+        }
+
+        foreach (var row in rows)
+        {
+            long? rowId = null;
+            if (rowIdIndex >= 0 && rowIdIndex < row.Count && row[rowIdIndex] is not null)
+            {
+                rowId = Convert.ToInt64(row[rowIdIndex], System.Globalization.CultureInfo.InvariantCulture);
+            }
+
+            Rows.Add(new SqliteGridRow
+            {
+                RowId = rowId,
+                Cells = row.Select(FormatCell).ToList()
+            });
+        }
+
+        TotalRows = total;
+        PageOffset = offset;
+        GridChanged?.Invoke(this, EventArgs.Empty);
+    }
+
+    private void ClearGrid()
+    {
+        Columns.Clear();
+        Rows.Clear();
+        PageOffset = 0;
+        TotalRows = 0;
+        PageLabel = "";
+        GridChanged?.Invoke(this, EventArgs.Empty);
+    }
+
+    private static string FormatCell(object? value)
+        => value switch
+        {
+            null => "",
+            byte[] bytes => "BLOB (" + bytes.Length + " bytes)",
+            DateTime dt => dt.ToString("O"),
+            DateTimeOffset dto => dto.ToString("O"),
+            IFormattable f => f.ToString(null, System.Globalization.CultureInfo.InvariantCulture) ?? "",
+            _ => value.ToString() ?? ""
+        };
+
+    public async ValueTask DisposeAsync()
+    {
+        if (_session is not null)
+        {
+            await _session.DisposeAsync().ConfigureAwait(false);
+            _session = null;
+        }
+    }
+}
+
+public sealed class SqliteGridRow
+{
+    public long? RowId { get; init; }
+    public required IReadOnlyList<string> Cells { get; init; }
+}

src/Explorer.Presentation/ViewModels/DuplicateViewModel.cs

@@ -1,18 +1,22 @@
 using System.Collections.ObjectModel;
+using System.Threading.Channels;
 using CommunityToolkit.Mvvm.ComponentModel;
 using CommunityToolkit.Mvvm.Input;
 using Explorer.Analysis;
 using Explorer.Application;
 using Explorer.Contracts;
 using Explorer.Domain;
+using Explorer.Domain.Abstractions;
 
 namespace Explorer.Presentation.ViewModels;
 
 public sealed partial class DuplicateViewModel : ObservableObject
 {
     private readonly IIndexMutations _mutations;
+    private readonly IIndexingHost _indexing;
     private readonly SourceManager _sources;
     private readonly AnalysisService _analysis;
+    private CancellationTokenSource? _load;
 
     [ObservableProperty] private bool _isOpen;
     [ObservableProperty] private bool _isBusy;
@@ -20,9 +24,14 @@ public sealed partial class DuplicateViewModel : ObservableObject
     [ObservableProperty] private bool _showIntentional;
     [ObservableProperty] private bool _showHardlinks;
 
-    public DuplicateViewModel(IIndexMutations mutations, SourceManager sources, AnalysisService analysis)
+    public DuplicateViewModel(
+        IIndexMutations mutations,
+        IIndexingHost indexing,
+        SourceManager sources,
+        AnalysisService analysis)
     {
         _mutations = mutations;
+        _indexing = indexing;
         _sources = sources;
         _analysis = analysis;
         Groups = [];
@@ -35,6 +44,7 @@ public sealed partial class DuplicateViewModel : ObservableObject
     [RelayCommand]
     public Task CloseAsync()
     {
+        _load?.Cancel();
         IsOpen = false;
         return Task.CompletedTask;
     }
@@ -42,32 +52,98 @@ public sealed partial class DuplicateViewModel : ObservableObject
     [RelayCommand]
     public async Task OpenAsync()
     {
+        _load?.Cancel();
+        var cts = new CancellationTokenSource();
+        _load = cts;
+        var ct = cts.Token;
+
         IsOpen = true;
         IsBusy = true;
         Status = "Finding size collisions…";
         Groups.Clear();
-        try
-        {
-            var groups = await Task.Run(async () =>
-            {
-                await _mutations.EnqueueHashCollisionsAsync(null).ConfigureAwait(false);
-                var classified = await _analysis.GetClassifiedDuplicatesAsync(200).ConfigureAwait(false);
-                var sources = (await _sources.RefreshOnlineStateAsync().ConfigureAwait(false)).ToDictionary(s => s.Id);
-                return classified
-                    .Select(g => DuplicateGroupViewModel.From(g, sources))
-                    .ToList();
-            }).ConfigureAwait(true);
-
         var hiddenIntentional = 0;
         var hiddenHardlinks = 0;
-            foreach (var group in groups)
+        try
         {
+            await _mutations.EnqueueHashCollisionsAsync(null, ct).ConfigureAwait(true);
+            ct.ThrowIfCancellationRequested();
+            Status = "Loading duplicate groups…";
+            var sources = (await _sources.RefreshOnlineStateAsync(ct).ConfigureAwait(true))
+                .ToDictionary(s => s.Id);
+            var channel = Channel.CreateUnbounded<ClassifiedDuplicateGroup>(
+                new UnboundedChannelOptions { SingleReader = true, SingleWriter = true });
+            var stream = Task.Run(async () =>
+            {
+                try
+                {
+                    return await _analysis.StreamClassifiedDuplicatesAsync(
+                            200,
+                            new DirectProgress<ClassifiedDuplicateGroup>(g => channel.Writer.TryWrite(g)),
+                            verifyPresence: false,
+                            ct)
+                        .ConfigureAwait(false);
+                }
+                finally
+                {
+                    channel.Writer.TryComplete();
+                }
+            }, ct);
+
+            var added = 0;
+            await foreach (var classified in channel.Reader.ReadAllAsync(ct).ConfigureAwait(true))
+            {
+                ApplyGroup(classified, sources, ref hiddenIntentional, ref hiddenHardlinks);
+                added++;
+                if (added % 24 == 0)
+                {
+                    await Task.Yield();
+                }
+            }
+
+            await stream.ConfigureAwait(true);
+            Status = BuildStatus(Groups.Count, hiddenIntentional, hiddenHardlinks);
+            IsBusy = false;
+            _ = VerifyOnDiskAsync(sources, cts, hiddenIntentional, hiddenHardlinks);
+        }
+        catch (OperationCanceledException)
+        {
+            if (IsOpen && ReferenceEquals(_load, cts))
+            {
+                Status = Groups.Count > 0
+                    ? BuildStatus(Groups.Count, hiddenIntentional, hiddenHardlinks)
+                    : "Cancelled.";
+            }
+        }
+        catch (Exception)
+        {
+            if (IsOpen && ReferenceEquals(_load, cts))
+            {
+                Status = "Could not load duplicates.";
+            }
+        }
+        finally
+        {
+            if (ReferenceEquals(_load, cts))
+            {
+                IsBusy = false;
+            }
+        }
+    }
+
+    private void ApplyGroup(
+        ClassifiedDuplicateGroup classified,
+        IReadOnlyDictionary<long, Source> sources,
+        ref int hiddenIntentional,
+        ref int hiddenHardlinks)
+    {
+        var group = DuplicateGroupViewModel.From(classified, sources);
         if (group.Classification == DuplicateClass.Hardlink)
         {
             if (!ShowHardlinks)
             {
                 hiddenHardlinks++;
-                        continue;
+                Status = LiveStatus(Groups.Count, hiddenIntentional, hiddenHardlinks);
+                return;
             }
         }
         else if (DuplicateClassifier.IsIntentional(group.Classification))
@@ -75,23 +151,129 @@ public sealed partial class DuplicateViewModel : ObservableObject
             if (!ShowIntentional)
             {
                 hiddenIntentional++;
-                        continue;
+                Status = LiveStatus(Groups.Count, hiddenIntentional, hiddenHardlinks);
+                return;
             }
         }
 
         Groups.Add(group);
+        Status = LiveStatus(Groups.Count, hiddenIntentional, hiddenHardlinks);
+    }
+
+    private async Task VerifyOnDiskAsync(
+        IReadOnlyDictionary<long, Source> sources,
+        CancellationTokenSource cts,
+        int hiddenIntentional,
+        int hiddenHardlinks)
+    {
+        var ct = cts.Token;
+        List<DuplicateGroupViewModel> snapshot;
+        try
+        {
+            snapshot = Groups.ToList();
+        }
+        catch (Exception)
+        {
+            return;
+        }
+
+        if (snapshot.Count == 0)
+        {
+            return;
+        }
+
+        IReadOnlyList<(DuplicateGroupViewModel Old, DuplicateGroupViewModel? Next)> changes;
+        HashSet<(long SourceId, string PathRel)> reconcile;
+        try
+        {
+            (changes, reconcile) = await Task.Run(
+                    () => ScanMissing(snapshot, sources, ct),
+                    ct)
+                .ConfigureAwait(true);
+        }
+        catch (OperationCanceledException)
+        {
+            return;
+        }
+
+        if (!IsOpen || !ReferenceEquals(_load, cts) || ct.IsCancellationRequested)
+        {
+            return;
+        }
+
+        foreach (var (old, next) in changes)
+        {
+            var index = Groups.IndexOf(old);
+            if (index < 0)
+            {
+                continue;
+            }
+
+            if (next is null)
+            {
+                Groups.RemoveAt(index);
+            }
+            else
+            {
+                Groups[index] = next;
+            }
+        }
+
+        foreach (var (sourceId, pathRel) in reconcile)
+        {
+            _indexing.EnqueueReconcile(sourceId, pathRel);
         }
 
         Status = BuildStatus(Groups.Count, hiddenIntentional, hiddenHardlinks);
     }
-        catch (Exception)
+
+    private static (
+        List<(DuplicateGroupViewModel Old, DuplicateGroupViewModel? Next)> Changes,
+        HashSet<(long SourceId, string PathRel)> Reconcile)
+        ScanMissing(
+            IReadOnlyList<DuplicateGroupViewModel> groups,
+            IReadOnlyDictionary<long, Source> sources,
+            CancellationToken cancellationToken)
     {
-            Status = "Could not load duplicates.";
-        }
-        finally
+        var changes = new List<(DuplicateGroupViewModel, DuplicateGroupViewModel?)>();
+        var reconcile = new HashSet<(long, string)>();
+        foreach (var group in groups)
         {
-            IsBusy = false;
+            cancellationToken.ThrowIfCancellationRequested();
+            var kept = new List<IndexEntry>(group.Entries.Count);
+            var dropped = false;
+            foreach (var entry in group.Entries)
+            {
+                if (!sources.TryGetValue(entry.SourceId, out var source)
+                    || string.IsNullOrWhiteSpace(source.LastRootPath)
+                    || !IndexedPathPresence.RootReachable(source.LastRootPath)
+                    || IndexedPathPresence.FileExists(source.LastRootPath, entry.PathRel))
+                {
+                    kept.Add(entry);
+                    continue;
                 }
+
+                dropped = true;
+                var prefix = IndexedPathPresence.HighestMissingPrefix(source.LastRootPath, entry.PathRel)
+                             ?? entry.PathRel;
+                reconcile.Add((entry.SourceId, IndexedPathPresence.ReconcilePath(entry.PathRel, prefix)));
+            }
+
+            if (!dropped)
+            {
+                continue;
+            }
+
+            if (kept.Count < 2)
+            {
+                changes.Add((group, null));
+                continue;
+            }
+
+            changes.Add((group, group.WithEntries(kept, sources)));
+        }
+
+        return (changes, reconcile);
     }
 
     [RelayCommand]
@@ -147,6 +329,19 @@ public sealed partial class DuplicateViewModel : ObservableObject
         }
     }
 
+    private static string LiveStatus(int visible, int hiddenIntentional, int hiddenHardlinks)
+    {
+        var extra = hiddenIntentional + hiddenHardlinks;
+        if (visible == 0 && extra == 0)
+        {
+            return "Loading duplicate groups…";
+        }
+
+        return extra == 0
+            ? $"{visible} duplicate groups so far…"
+            : $"{visible} duplicate groups so far · {extra} hidden";
+    }
+
     private static string BuildStatus(int visible, int hiddenIntentional, int hiddenHardlinks)
     {
         if (visible > 0)
@@ -164,12 +359,18 @@ public sealed partial class DuplicateViewModel : ObservableObject
 
         return "No confirmed duplicates yet. Hashing continues in the background.";
     }
+
+    private sealed class DirectProgress<T>(Action<T> action) : IProgress<T>
+    {
+        public void Report(T value) => action(value);
+    }
 }
 
 public sealed class DuplicateGroupViewModel
 {
     public required IReadOnlyList<IndexEntry> Entries { get; init; }
     public DuplicateClass Classification { get; init; }
+    public required string Header { get; init; }
     public required string ClassLabel { get; init; }
     public required string SizeLabel { get; init; }
     public required string Summary { get; init; }
@@ -178,6 +379,30 @@ public sealed class DuplicateGroupViewModel
     public bool CanMarkAccidental { get; init; }
     public IReadOnlyList<DuplicateFileViewModel> Files { get; init; } = [];
 
+    public DuplicateGroupViewModel WithEntries(
+        IReadOnlyList<IndexEntry> entries,
+        IReadOnlyDictionary<long, Source> sources)
+    {
+        var unique = DuplicateClassifier.UniqueFileCount(entries);
+        var size = entries.Count > 0 ? entries[0].SizeBytes : 0;
+        return From(
+            new ClassifiedDuplicateGroup
+            {
+                Group = new DuplicateGroup
+                {
+                    SizeBytes = size,
+                    Entries = entries,
+                    SameFileId = DuplicateClassifier.IsHardlinkOnly(entries)
+                },
+                Classification = Classification,
+                UniqueFileCount = unique,
+                WastedBytes = Classification == DuplicateClass.Hardlink || unique <= 1
+                    ? 0
+                    : size * (unique - 1)
+            },
+            sources);
+    }
+
     public static DuplicateGroupViewModel From(
         ClassifiedDuplicateGroup classified,
         IReadOnlyDictionary<long, Source> sources)
@@ -197,16 +422,27 @@ public sealed class DuplicateGroupViewModel
             };
         }).ToList();
 
+        var classLabel = classified.Classification == DuplicateClass.Unknown
+            ? ""
+            : DuplicateClassifier.Label(classified.Classification);
+        var sizeLabel = Formatters.Size(classified.Group.SizeBytes);
+        var summary = $"{classified.UniqueFileCount} copies · {classified.Group.Entries.Count} names";
+        var wasted = classified.WastedBytes > 0
+            ? Formatters.Size(classified.WastedBytes) + " wasted"
+            : "No extra space";
+        var header = string.IsNullOrEmpty(classLabel)
+            ? $"{sizeLabel} · {summary} · {wasted}"
+            : $"{classLabel} · {sizeLabel} · {summary} · {wasted}";
+
         return new DuplicateGroupViewModel
         {
             Entries = classified.Group.Entries,
             Classification = classified.Classification,
-            ClassLabel = DuplicateClassifier.Label(classified.Classification),
-            SizeLabel = Formatters.Size(classified.Group.SizeBytes),
-            Summary = $"{classified.UniqueFileCount} copies · {classified.Group.Entries.Count} names",
-            WastedLabel = classified.WastedBytes > 0
-                ? Formatters.Size(classified.WastedBytes) + " wasted"
-                : "No extra space",
+            Header = header,
+            ClassLabel = classLabel,
+            SizeLabel = sizeLabel,
+            Summary = summary,
+            WastedLabel = wasted,
             CanMarkIntentional = classified.Classification != DuplicateClass.Hardlink
                                  && classified.Classification != DuplicateClass.Intentional,
             CanMarkAccidental = classified.Classification != DuplicateClass.Hardlink

src/Explorer.Presentation/ViewModels/HostActivityMonitorViewModel.cs

@@ -0,0 +1,324 @@
+using System.Collections.ObjectModel;
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
+using Explorer.Contracts;
+using Explorer.Domain;
+
+namespace Explorer.Presentation.ViewModels;
+
+public sealed partial class HostActivityMonitorViewModel : ObservableObject, IDisposable
+{
+    public const int LiveTailLimit = 40;
+
+    private readonly IHostActivity _activity;
+    private readonly IBackgroundMaintenance? _maintenance;
+    private readonly SynchronizationContext? _ui = SynchronizationContext.Current;
+    private CancellationTokenSource? _loop;
+    private int _refreshBusy;
+    private int _applyQueued;
+    private HostActivitySnapshot? _pendingSnap;
+    private string _eventsFingerprint = "";
+
+    [ObservableProperty] private string _summary = "Connecting…";
+    [ObservableProperty] private string _maintenanceText = "";
+    [ObservableProperty] private string _indexingText = "";
+    [ObservableProperty] private string _hashText = "";
+    [ObservableProperty] private string _transferText = "";
+    [ObservableProperty] private string _status = "";
+    [ObservableProperty] private bool _isLive;
+    [ObservableProperty] private string _logCaption = "Activity log · live";
+
+    public HostActivityMonitorViewModel(
+        IHostActivity activity,
+        IBackgroundMaintenance? maintenance = null,
+        IIndexingHost? indexing = null,
+        ITransferHost? transfers = null)
+    {
+        _activity = activity;
+        _maintenance = maintenance;
+        _ = indexing;
+        _ = transfers;
+        Jobs = [];
+        Events = [];
+    }
+
+    public ObservableCollection<HostActivityJobRow> Jobs { get; }
+    public ObservableCollection<HostActivityEventRow> Events { get; }
+
+    public event EventHandler? EventsReplaced;
+
+    public void Start()
+    {
+        if (_loop is not null)
+        {
+            return;
+        }
+
+        _loop = new CancellationTokenSource();
+        IsLive = true;
+        _ = RunLoopAsync(_loop.Token);
+    }
+
+    public void Dispose()
+    {
+        _loop?.Cancel();
+        _loop?.Dispose();
+        _loop = null;
+        IsLive = false;
+    }
+
+    [RelayCommand]
+    private Task RefreshAsync() => RefreshCoreAsync(CancellationToken.None);
+
+    [RelayCommand]
+    private void RunMaintenanceNow() => _maintenance?.RunNow();
+
+    private async Task RunLoopAsync(CancellationToken cancellationToken)
+    {
+        try
+        {
+            await RefreshCoreAsync(cancellationToken).ConfigureAwait(false);
+            using var timer = new PeriodicTimer(TimeSpan.FromSeconds(1));
+            while (await timer.WaitForNextTickAsync(cancellationToken).ConfigureAwait(false))
+            {
+                await RefreshCoreAsync(cancellationToken).ConfigureAwait(false);
+            }
+        }
+        catch (OperationCanceledException)
+        {
+            // window closed
+        }
+        catch (Exception ex)
+        {
+            Post(() =>
+            {
+                Status = "Monitor stopped: " + ex.Message;
+                IsLive = false;
+            });
+        }
+    }
+
+    private async Task RefreshCoreAsync(CancellationToken cancellationToken)
+    {
+        if (Interlocked.CompareExchange(ref _refreshBusy, 1, 0) != 0)
+        {
+            return;
+        }
+
+        try
+        {
+            var snap = await _activity.GetSnapshotAsync(cancellationToken).ConfigureAwait(false);
+            if (cancellationToken.IsCancellationRequested)
+            {
+                return;
+            }
+
+            Volatile.Write(ref _pendingSnap, snap);
+            if (Interlocked.Exchange(ref _applyQueued, 1) == 0)
+            {
+                Post(FlushPendingSnapshot);
+            }
+        }
+        catch (OperationCanceledException)
+        {
+            throw;
+        }
+        catch (Exception ex)
+        {
+            Post(() => Status = "Could not refresh: " + ex.Message);
+        }
+        finally
+        {
+            Interlocked.Exchange(ref _refreshBusy, 0);
+        }
+    }
+
+    private void FlushPendingSnapshot()
+    {
+        Interlocked.Exchange(ref _applyQueued, 0);
+        var snap = Interlocked.Exchange(ref _pendingSnap, null);
+        if (snap is null || _loop is null)
+        {
+            return;
+        }
+
+        Apply(snap);
+        Status = "Updated " + snap.Utc.ToLocalTime().ToString("HH:mm:ss");
+        IsLive = true;
+
+        if (Volatile.Read(ref _pendingSnap) is not null && Interlocked.Exchange(ref _applyQueued, 1) == 0)
+        {
+            Post(FlushPendingSnapshot);
+        }
+    }
+
+    private void Apply(HostActivitySnapshot snap)
+    {
+        var maint = snap.Maintenance.Message;
+        if (string.IsNullOrWhiteSpace(maint))
+        {
+            maint = snap.Maintenance.Allowed ? "Idle allowed" : "Idle paused";
+            if (!string.IsNullOrWhiteSpace(snap.Maintenance.SkipReason))
+            {
+                maint += " · " + snap.Maintenance.SkipReason;
+            }
+        }
+
+        MaintenanceText = maint;
+        IndexingText = FormatIndexing(snap);
+        HashText = FormatHash(snap);
+        TransferText = FormatTransfers(snap);
+        Summary = BuildSummary(snap, maint);
+
+        Jobs.Clear();
+        foreach (var job in snap.IndexingJobs)
+        {
+            Jobs.Add(new HostActivityJobRow
+            {
+                Title = job.Kind + " · " + job.SourceName,
+                Detail = (job.PathRel ?? "") + (job.VerifyChildren ? " · verify children" : ""),
+                Origin = job.Origin
+            });
+        }
+
+        ReplaceEvents(snap.RecentEvents);
+    }
+
+    private void ReplaceEvents(IReadOnlyList<HostActivityEvent> recent)
+    {
+        var tail = recent.Count <= LiveTailLimit
+            ? recent
+            : recent.Skip(recent.Count - LiveTailLimit).ToList();
+        var fingerprint = tail.Count == 0
+            ? ""
+            : tail.Count + "|" + tail[^1].Utc.UtcTicks + "|" + tail[^1].Message;
+        if (fingerprint == _eventsFingerprint)
+        {
+            return;
+        }
+
+        _eventsFingerprint = fingerprint;
+        Events.Clear();
+        foreach (var evt in tail)
+        {
+            Events.Add(new HostActivityEventRow
+            {
+                Time = evt.Utc.ToLocalTime().ToString("HH:mm:ss"),
+                Category = evt.Category,
+                Message = evt.Message
+            });
+        }
+
+        LogCaption = Events.Count == 0
+            ? "Activity log · live"
+            : "Activity log · last " + Events.Count + " (newest at bottom)";
+        EventsReplaced?.Invoke(this, EventArgs.Empty);
+    }
+
+    private static string FormatIndexing(HostActivitySnapshot snap)
+    {
+        if (snap.IndexingJobs.Count > 0)
+        {
+            var job = snap.IndexingJobs[0];
+            return job.Kind + " · " + job.SourceName
+                   + (string.IsNullOrEmpty(job.PathRel) ? "" : " · " + job.PathRel)
+                   + " · " + job.Origin
+                   + (string.IsNullOrEmpty(snap.LastIndexPath) ? "" : " · " + snap.LastIndexPath);
+        }
+
+        if (!string.IsNullOrWhiteSpace(snap.LastIndexPath))
+        {
+            return (snap.LastIndexStatus ?? "Idle") + " · " + snap.LastIndexFilesDone + " files · " + snap.LastIndexPath;
+        }
+
+        return snap.IdleQueued > 0
+            ? "Idle queue " + snap.IdleQueued + (snap.IdleAllowed ? " (allowed)" : " (held)")
+            : "Idle";
+    }
+
+    private static string FormatHash(HostActivitySnapshot snap)
+    {
+        if (snap.HashPaused && snap.HashPending == 0)
+        {
+            return "Paused";
+        }
+
+        if (snap.HashPaused)
+        {
+            return "Paused · " + snap.HashPending.ToString("N0") + " pending";
+        }
+
+        if (!string.IsNullOrWhiteSpace(snap.HashCurrentPath))
+        {
+            return snap.HashPending.ToString("N0") + " pending · " + snap.HashCurrentPath;
+        }
+
+        return snap.HashPending > 0 ? snap.HashPending.ToString("N0") + " pending" : "Idle";
+    }
+
+    private static string FormatTransfers(HostActivitySnapshot snap)
+    {
+        var text = snap.TransfersActive + " active · " + snap.TransfersQueued + " queued"
+                   + (snap.TransfersPaused ? " · paused" : "");
+        if (!string.IsNullOrWhiteSpace(snap.TransferCurrentPath))
+        {
+            text += " · " + snap.TransferCurrentPath;
+        }
+
+        return text;
+    }
+
+    private static string BuildSummary(HostActivitySnapshot snap, string maintenanceText)
+    {
+        if (snap.IndexingJobs.Count > 0)
+        {
+            var job = snap.IndexingJobs[0];
+            var more = snap.IndexingJobs.Count > 1 ? " (+" + (snap.IndexingJobs.Count - 1) + " more)" : "";
+            return job.Kind + " · " + job.SourceName + " · " + job.Origin + more;
+        }
+
+        if (!string.IsNullOrWhiteSpace(maintenanceText)
+            && !maintenanceText.StartsWith("Idle allowed", StringComparison.Ordinal)
+            && !maintenanceText.StartsWith("Idle paused", StringComparison.Ordinal))
+        {
+            return maintenanceText;
+        }
+
+        if (!snap.HashPaused && snap.HashPending > 0)
+        {
+            return "Hashing · " + snap.HashPending.ToString("N0") + " pending";
+        }
+
+        if (snap.TransfersActive > 0)
+        {
+            return "Transfers · " + snap.TransfersActive + " active";
+        }
+
+        return string.IsNullOrWhiteSpace(maintenanceText) ? "Host idle" : maintenanceText;
+    }
+
+    private void Post(Action action)
+    {
+        if (_ui is null)
+        {
+            action();
+            return;
+        }
+
+        _ui.Post(_ => action(), null);
+    }
+}
+
+public sealed class HostActivityJobRow
+{
+    public required string Title { get; init; }
+    public required string Detail { get; init; }
+    public required string Origin { get; init; }
+}
+
+public sealed class HostActivityEventRow
+{
+    public required string Time { get; init; }
+    public required string Category { get; init; }
+    public required string Message { get; init; }
+}

src/Explorer.Presentation/ViewModels/MainViewModel.cs

@@ -37,11 +37,18 @@ public sealed partial class MainViewModel : ObservableObject
     private readonly IThumbnailService? _thumbnails;
     private readonly IHostConnection? _host;
     private readonly IBackgroundMaintenance? _maintenance;
+    private readonly ITransferHost _transferHost;
+    private readonly IHostActivity? _hostActivity;
+    private readonly ISqliteDatabaseSessionFactory? _databaseSessions;
+    private readonly IAppEnvironment? _environment;
     private readonly IShellContextMenu? _shellMenu;
     private readonly IMediaTagService? _tags;
     private bool _hostStopped;
     private List<string> _clipboard = [];
     private bool _clipboardIsCut;
+    private int _overlayDirty;
+    private int _overlayRunning;
+    private DateTimeOffset _lastOverlayRefreshUtc = DateTimeOffset.MinValue;
 
     [ObservableProperty] private ExplorerTabViewModel _activeTab = null!;
     [ObservableProperty] private string _pathText = "";
@@ -104,12 +111,19 @@ public sealed partial class MainViewModel : ObservableObject
         IThumbnailService? thumbnails = null,
         IHostConnection? hostConnection = null,
         IBackgroundMaintenance? maintenance = null,
+        IHostActivity? hostActivity = null,
+        ISqliteDatabaseSessionFactory? databaseSessions = null,
+        IAppEnvironment? environment = null,
         IShellContextMenu? shellMenu = null,
         IMediaTagService? tags = null)
     {
         _browse = browse;
         _ops = ops;
         _indexing = workbench.Indexing;
+        _transferHost = workbench.Transfers;
+        _hostActivity = hostActivity;
+        _databaseSessions = databaseSessions;
+        _environment = environment;
         _sources = sources;
         _pathHistory = pathHistory;
         _providers = providers;
@@ -174,7 +188,7 @@ public sealed partial class MainViewModel : ObservableObject
         Tree = new NavigationTreeViewModel(sources, browse, providers, cloudPlaces, preferences, knownFolders);
         Search = new SearchViewModel(search, sources, volumes);
         Analysis = new AnalysisViewModel(analysis);
-        Duplicates = new DuplicateViewModel(mutations, sources, analysis);
+        Duplicates = new DuplicateViewModel(mutations, _indexing, sources, analysis);
         Duplicates.RevealPath += (_, path) => _ = RevealDuplicateAsync(path);
         _sources.PresenceChanged += (_, source) =>
         {
@@ -207,16 +221,7 @@ public sealed partial class MainViewModel : ObservableObject
         {
             if (p.IndexRefresh)
             {
-                void Refresh() => _ = RefreshIndexOverlayAsync();
-                if (_ui is { } refreshCtx)
-                {
-                    refreshCtx.Post(_ => Refresh(), null);
-                }
-                else
-                {
-                    Refresh();
-                }
-
+                ScheduleIndexOverlayRefresh();
                 return;
             }
 
@@ -243,6 +248,53 @@ public sealed partial class MainViewModel : ObservableObject
         };
     }
 
+    private void ScheduleIndexOverlayRefresh()
+    {
+        Interlocked.Exchange(ref _overlayDirty, 1);
+        if (Interlocked.CompareExchange(ref _overlayRunning, 1, 0) != 0)
+        {
+            return;
+        }
+
+        void Start() => _ = RunIndexOverlayRefreshAsync();
+        if (_ui is { } ctx)
+        {
+            ctx.Post(_ => Start(), null);
+        }
+        else
+        {
+            Start();
+        }
+    }
+
+    private async Task RunIndexOverlayRefreshAsync()
+    {
+        try
+        {
+            do
+            {
+                Interlocked.Exchange(ref _overlayDirty, 0);
+                var wait = TimeSpan.FromSeconds(2.5) - (DateTimeOffset.UtcNow - _lastOverlayRefreshUtc);
+                if (wait > TimeSpan.Zero)
+                {
+                    await Task.Delay(wait).ConfigureAwait(true);
+                }
+
+                _lastOverlayRefreshUtc = DateTimeOffset.UtcNow;
+                await RefreshIndexOverlayAsync().ConfigureAwait(true);
+            }
+            while (Volatile.Read(ref _overlayDirty) == 1);
+        }
+        finally
+        {
+            Interlocked.Exchange(ref _overlayRunning, 0);
+            if (Interlocked.Exchange(ref _overlayDirty, 0) == 1)
+            {
+                ScheduleIndexOverlayRefresh();
+            }
+        }
+    }
+
     public ObservableCollection<ExplorerTabViewModel> Tabs { get; }
     public ObservableCollection<string> PathHistory { get; }
     public NavigationTreeViewModel Tree { get; }
@@ -688,6 +740,16 @@ public sealed partial class MainViewModel : ObservableObject
     public GitChangesViewModel CreateGitChangesViewModel()
         => new(_gitCommands, _workspace, _hydration);
 
+    public HostActivityMonitorViewModel? CreateHostActivityMonitorViewModel()
+        => _hostActivity is null
+            ? null
+            : new HostActivityMonitorViewModel(_hostActivity, _maintenance, _indexing, _transferHost);
+
+    public DatabaseViewerViewModel? CreateDatabaseViewerViewModel()
+        => _databaseSessions is null || _environment is null
+            ? null
+            : new DatabaseViewerViewModel(_databaseSessions, _environment);
+
     public async Task<GitCommitViewModel?> CreateGitCommitViewModelAsync()
     {
         var path = GitWorkspacePath();

src/Explorer.Storage.Sqlite/AnalysisHistoryHashStores.cs

@@ -228,9 +228,16 @@ internal sealed class HashStore : IHashStore
     public async Task<bool> HasPendingAsync(CancellationToken cancellationToken = default)
     {
         await using var conn = await _store.OpenReadAsync(cancellationToken).ConfigureAwait(false);
-        var count = await conn.ExecuteScalarAsync<long>(
+        var hit = await conn.ExecuteScalarAsync<long?>(
+            "SELECT 1 FROM hash_queue WHERE state IN ('Pending','PartialDone') LIMIT 1").ConfigureAwait(false);
+        return hit is 1;
+    }
+
+    public async Task<long> CountPendingAsync(CancellationToken cancellationToken = default)
+    {
+        await using var conn = await _store.OpenReadAsync(cancellationToken).ConfigureAwait(false);
+        return await conn.ExecuteScalarAsync<long>(
             "SELECT COUNT(*) FROM hash_queue WHERE state IN ('Pending','PartialDone')").ConfigureAwait(false);
-        return count > 0;
     }
 
     public async Task<IReadOnlyList<HashWorkItem>> DequeueAsync(int take, CancellationToken cancellationToken = default)
@@ -306,36 +313,100 @@ internal sealed class HashStore : IHashStore
         }, cancellationToken);
 
     public async Task<IReadOnlyList<DuplicateGroup>> GetDuplicateGroupsAsync(long? sourceId, string? pathPrefix, int take, CancellationToken cancellationToken = default)
+    {
+        var hashes = await GetDuplicateHashesAsync(sourceId, pathPrefix, take, cancellationToken).ConfigureAwait(false);
+        return await GetDuplicateGroupsByHashesAsync(hashes, cancellationToken).ConfigureAwait(false);
+    }
+
+    public async Task<IReadOnlyList<byte[]>> GetDuplicateHashesAsync(
+        long? sourceId,
+        string? pathPrefix,
+        int take,
+        CancellationToken cancellationToken = default)
     {
         await using var conn = await _store.OpenReadAsync(cancellationToken).ConfigureAwait(false);
         var sql = """
-            SELECT * FROM entries
+            SELECT content_hash
+            FROM entries
             WHERE is_dir=0 AND status=0 AND hash_state=2 AND content_hash IS NOT NULL
             """;
-        if (sourceId is not null) sql += " AND source_id=@sourceId";
+        if (sourceId is not null)
+        {
+            sql += " AND source_id=@sourceId";
+        }
+
         if (!string.IsNullOrEmpty(pathPrefix))
+        {
             sql += " AND (path_rel=@pathPrefix OR path_rel LIKE @like ESCAPE '\\')";
-        sql += " ORDER BY content_hash, file_id";
+        }
+
+        sql += """
+             GROUP BY content_hash
+             HAVING COUNT(*) > 1
+             ORDER BY MAX(size_bytes) DESC
+             LIMIT @take
+            """;
         var like = string.IsNullOrEmpty(pathPrefix) ? null : pathPrefix.Replace("\\", "\\\\") + "\\\\%";
-        var rows = (await conn.QueryAsync<EntryRow>(sql, new { sourceId, pathPrefix, like }).ConfigureAwait(false))
+        var rows = await conn.QueryAsync<HashBlobRow>(sql, new { sourceId, pathPrefix, like, take })
+            .ConfigureAwait(false);
+        return rows.Select(r => r.content_hash).Where(h => h.Length > 0).ToList();
+    }
+
+    public async Task<IReadOnlyList<DuplicateGroup>> GetDuplicateGroupsByHashesAsync(
+        IReadOnlyList<byte[]> hashes,
+        CancellationToken cancellationToken = default)
+    {
+        if (hashes.Count == 0)
+        {
+            return [];
+        }
+
+        await using var conn = await _store.OpenReadAsync(cancellationToken).ConfigureAwait(false);
+        var parameters = new DynamicParameters();
+        var ors = new string[hashes.Count];
+        for (var i = 0; i < hashes.Count; i++)
+        {
+            var name = "h" + i;
+            ors[i] = "content_hash=@" + name;
+            parameters.Add(name, hashes[i]);
+        }
+
+        var sql = $"""
+            SELECT * FROM entries
+            WHERE is_dir=0 AND status=0 AND hash_state=2 AND ({string.Join(" OR ", ors)})
+            ORDER BY content_hash, file_id
+            """;
+        var rows = (await conn.QueryAsync<EntryRow>(sql, parameters).ConfigureAwait(false))
             .Select(r => r.ToModel())
             .ToList();
-
-        return rows
-            .GroupBy(e => Convert.ToHexString(e.ContentHash!))
-            .Where(g => g.Count() > 1)
-            .Take(take)
-            .Select(g =>
+        var byHash = rows
+            .Where(e => e.ContentHash is { Length: > 0 })
+            .GroupBy(e => Convert.ToHexString(e.ContentHash!), StringComparer.Ordinal)
+            .ToDictionary(g => g.Key, g => g.ToList(), StringComparer.Ordinal);
+        var result = new List<DuplicateGroup>();
+        var seen = new HashSet<string>(StringComparer.Ordinal);
+        foreach (var hash in hashes)
         {
-                var list = g.ToList();
-                return new DuplicateGroup
+            var hex = Convert.ToHexString(hash);
+            if (!seen.Add(hex) || !byHash.TryGetValue(hex, out var list) || list.Count < 2)
+            {
+                continue;
+            }
+
+            result.Add(new DuplicateGroup
             {
                 SizeBytes = list[0].SizeBytes,
                 Hash = list[0].ContentHash,
                 Entries = list,
                 SameFileId = DuplicateClassifier.IsHardlinkOnly(list)
-                };
-            })
-            .ToList();
+            });
+        }
+
+        return result;
+    }
+
+    private sealed class HashBlobRow
+    {
+        public byte[] content_hash { get; set; } = [];
     }
 }

src/Explorer.Storage.Sqlite/SchemaScript.cs

@@ -173,6 +173,7 @@ internal static class SchemaScript
           state TEXT NOT NULL
         )
         """,
+        "CREATE INDEX IF NOT EXISTS ix_hash_queue_state ON hash_queue(state, priority, size_bytes)",
         """
         CREATE TABLE source_stats_history (
           id INTEGER PRIMARY KEY,

src/Explorer.Storage.Sqlite/SqliteDatabaseSession.cs

@@ -0,0 +1,336 @@
+using System.Data;
+using System.Globalization;
+using Explorer.Application;
+using Explorer.Domain.Abstractions;
+using Microsoft.Data.Sqlite;
+
+namespace Explorer.Storage.Sqlite;
+
+public sealed class SqliteDatabaseSessionFactory(IAppEnvironment environment) : ISqliteDatabaseSessionFactory
+{
+    public ISqliteDatabaseSession Create() => new SqliteDatabaseSession(environment.DatabasePath);
+}
+
+public sealed class SqliteDatabaseSession : ISqliteDatabaseSession
+{
+    private readonly string _defaultIndexPath;
+    private SqliteConnection? _connection;
+    private IndexStoreLock? _writeLock;
+
+    public SqliteDatabaseSession(string defaultIndexPath) => _defaultIndexPath = defaultIndexPath;
+
+    public string? Path { get; private set; }
+    public bool IsOpen => _connection is { State: ConnectionState.Open };
+    public bool CanWrite { get; private set; }
+    public string ModeLabel { get; private set; } = "Closed";
+
+    public async Task OpenAsync(string path, bool preferWrite, CancellationToken cancellationToken = default)
+    {
+        ArgumentException.ThrowIfNullOrWhiteSpace(path);
+        await CloseAsync().ConfigureAwait(false);
+
+        var full = System.IO.Path.GetFullPath(path);
+        var isIndex = string.Equals(full, System.IO.Path.GetFullPath(_defaultIndexPath), StringComparison.OrdinalIgnoreCase);
+        var held = IndexStoreLock.IsHeld(full);
+        var wantWrite = preferWrite && !(isIndex && held);
+
+        if (wantWrite)
+        {
+            try
+            {
+                if (isIndex)
+                {
+                    _writeLock = IndexStoreLock.Acquire(full, TimeSpan.Zero);
+                }
+
+                _connection = new SqliteConnection(SqliteIndexStore.BuildConnectionString(full, readOnly: false));
+                await _connection.OpenAsync(cancellationToken).ConfigureAwait(false);
+                ApplyWritePragmas(_connection);
+                CanWrite = true;
+                ModeLabel = isIndex ? "Read-write (Workbench index)" : "Read-write";
+            }
+            catch
+            {
+                _writeLock?.Dispose();
+                _writeLock = null;
+                wantWrite = false;
+            }
+        }
+
+        if (!wantWrite)
+        {
+            _connection = new SqliteConnection(SqliteIndexStore.BuildConnectionString(full, readOnly: true));
+            await _connection.OpenAsync(cancellationToken).ConfigureAwait(false);
+            ApplyReadPragmas(_connection);
+            CanWrite = false;
+            ModeLabel = isIndex && held
+                ? "Read-only (index in use by host)"
+                : preferWrite
+                    ? "Read-only (could not open for write)"
+                    : "Read-only";
+        }
+
+        Path = full;
+    }
+
+    public Task CloseAsync()
+    {
+        if (_connection is not null)
+        {
+            _connection.Dispose();
+            _connection = null;
+        }
+
+        _writeLock?.Dispose();
+        _writeLock = null;
+        Path = null;
+        CanWrite = false;
+        ModeLabel = "Closed";
+        return Task.CompletedTask;
+    }
+
+    public async ValueTask DisposeAsync() => await CloseAsync().ConfigureAwait(false);
+
+    public async Task<IReadOnlyList<string>> ListTablesAsync(CancellationToken cancellationToken = default)
+    {
+        var conn = RequireOpen();
+        await using var cmd = conn.CreateCommand();
+        cmd.CommandText = """
+            SELECT name FROM sqlite_master
+            WHERE type='table' AND name NOT LIKE 'sqlite_%'
+            ORDER BY name COLLATE NOCASE
+            """;
+        var list = new List<string>();
+        await using var reader = await cmd.ExecuteReaderAsync(cancellationToken).ConfigureAwait(false);
+        while (await reader.ReadAsync(cancellationToken).ConfigureAwait(false))
+        {
+            list.Add(reader.GetString(0));
+        }
+
+        return list;
+    }
+
+    public async Task<SqliteTablePage> ReadTableAsync(
+        string table,
+        int offset,
+        int take,
+        CancellationToken cancellationToken = default)
+    {
+        var conn = RequireOpen();
+        var ident = QuoteIdent(table);
+        take = Math.Clamp(take, 1, 500);
+        offset = Math.Max(0, offset);
+
+        long total;
+        await using (var count = conn.CreateCommand())
+        {
+            count.CommandText = "SELECT COUNT(*) FROM " + ident;
+            total = Convert.ToInt64(await count.ExecuteScalarAsync(cancellationToken).ConfigureAwait(false), CultureInfo.InvariantCulture);
+        }
+
+        await using var cmd = conn.CreateCommand();
+        cmd.CommandText = "SELECT rowid AS _rowid_, * FROM " + ident + " LIMIT $take OFFSET $offset";
+        cmd.Parameters.AddWithValue("$take", take);
+        cmd.Parameters.AddWithValue("$offset", offset);
+        await using var reader = await cmd.ExecuteReaderAsync(cancellationToken).ConfigureAwait(false);
+        var (columns, rows) = await ReadGridAsync(reader, cancellationToken).ConfigureAwait(false);
+        return new SqliteTablePage
+        {
+            Columns = columns,
+            Rows = rows,
+            TotalRows = total,
+            Offset = offset
+        };
+    }
+
+    public async Task<SqliteQueryResult> ExecuteAsync(string sql, CancellationToken cancellationToken = default)
+    {
+        var conn = RequireOpen();
+        if (string.IsNullOrWhiteSpace(sql))
+        {
+            return new SqliteQueryResult { Message = "Empty SQL." };
+        }
+
+        var trimmed = sql.Trim().TrimEnd(';');
+        var isQuery = LooksLikeQuery(trimmed);
+        if (!CanWrite && !isQuery)
+        {
+            throw new InvalidOperationException("Database is open read-only.");
+        }
+
+        await using var cmd = conn.CreateCommand();
+        cmd.CommandText = trimmed;
+        if (isQuery)
+        {
+            await using var reader = await cmd.ExecuteReaderAsync(cancellationToken).ConfigureAwait(false);
+            var (columns, rows) = await ReadGridAsync(reader, cancellationToken).ConfigureAwait(false);
+            return new SqliteQueryResult
+            {
+                IsQuery = true,
+                Columns = columns,
+                Rows = rows,
+                Message = rows.Count + " row(s)"
+            };
+        }
+
+        var affected = await cmd.ExecuteNonQueryAsync(cancellationToken).ConfigureAwait(false);
+        return new SqliteQueryResult
+        {
+            IsQuery = false,
+            RecordsAffected = affected,
+            Message = affected + " row(s) affected"
+        };
+    }
+
+    public async Task UpdateCellAsync(
+        string table,
+        long rowId,
+        string column,
+        object? value,
+        CancellationToken cancellationToken = default)
+    {
+        EnsureWritable();
+        if (column.Equals("_rowid_", StringComparison.OrdinalIgnoreCase) || column.Equals("rowid", StringComparison.OrdinalIgnoreCase))
+        {
+            throw new InvalidOperationException("Cannot edit rowid.");
+        }
+
+        var conn = RequireOpen();
+        await using var cmd = conn.CreateCommand();
+        cmd.CommandText = "UPDATE " + QuoteIdent(table) + " SET " + QuoteIdent(column) + " = $v WHERE rowid = $id";
+        cmd.Parameters.AddWithValue("$v", value ?? DBNull.Value);
+        cmd.Parameters.AddWithValue("$id", rowId);
+        var n = await cmd.ExecuteNonQueryAsync(cancellationToken).ConfigureAwait(false);
+        if (n == 0)
+        {
+            throw new InvalidOperationException("No row updated.");
+        }
+    }
+
+    public async Task DeleteRowAsync(string table, long rowId, CancellationToken cancellationToken = default)
+    {
+        EnsureWritable();
+        var conn = RequireOpen();
+        await using var cmd = conn.CreateCommand();
+        cmd.CommandText = "DELETE FROM " + QuoteIdent(table) + " WHERE rowid = $id";
+        cmd.Parameters.AddWithValue("$id", rowId);
+        var n = await cmd.ExecuteNonQueryAsync(cancellationToken).ConfigureAwait(false);
+        if (n == 0)
+        {
+            throw new InvalidOperationException("No row deleted.");
+        }
+    }
+
+    public async Task InsertRowAsync(
+        string table,
+        IReadOnlyDictionary<string, object?> values,
+        CancellationToken cancellationToken = default)
+    {
+        EnsureWritable();
+        if (values.Count == 0)
+        {
+            throw new InvalidOperationException("No column values provided.");
+        }
+
+        var cols = values.Keys.Select(QuoteIdent).ToList();
+        var pars = values.Keys.Select((_, i) => "$p" + i).ToList();
+        var conn = RequireOpen();
+        await using var cmd = conn.CreateCommand();
+        cmd.CommandText = "INSERT INTO " + QuoteIdent(table) + " (" + string.Join(", ", cols) + ") VALUES ("
+                          + string.Join(", ", pars) + ")";
+        var i = 0;
+        foreach (var value in values.Values)
+        {
+            cmd.Parameters.AddWithValue("$p" + i, value ?? DBNull.Value);
+            i++;
+        }
+
+        await cmd.ExecuteNonQueryAsync(cancellationToken).ConfigureAwait(false);
+    }
+
+    private SqliteConnection RequireOpen()
+        => _connection ?? throw new InvalidOperationException("No database is open.");
+
+    private void EnsureWritable()
+    {
+        if (!CanWrite)
+        {
+            throw new InvalidOperationException("Database is open read-only.");
+        }
+    }
+
+    private static bool LooksLikeQuery(string sql)
+    {
+        var span = sql.AsSpan().TrimStart();
+        return span.StartsWith("SELECT", StringComparison.OrdinalIgnoreCase)
+               || span.StartsWith("WITH", StringComparison.OrdinalIgnoreCase)
+               || span.StartsWith("PRAGMA", StringComparison.OrdinalIgnoreCase)
+               || span.StartsWith("EXPLAIN", StringComparison.OrdinalIgnoreCase);
+    }
+
+    private static string QuoteIdent(string name)
+    {
+        if (string.IsNullOrWhiteSpace(name)
+            || name.Any(c => !(char.IsLetterOrDigit(c) || c is '_' or '$')))
+        {
+            throw new InvalidOperationException("Invalid identifier: " + name);
+        }
+
+        return "\"" + name.Replace("\"", "\"\"", StringComparison.Ordinal) + "\"";
+    }
+
+    private static async Task<(IReadOnlyList<string> Columns, IReadOnlyList<IReadOnlyList<object?>> Rows)> ReadGridAsync(
+        SqliteDataReader reader,
+        CancellationToken cancellationToken)
+    {
+        var columns = new string[reader.FieldCount];
+        for (var i = 0; i < reader.FieldCount; i++)
+        {
+            columns[i] = reader.GetName(i);
+        }
+
+        var rows = new List<IReadOnlyList<object?>>();
+        while (await reader.ReadAsync(cancellationToken).ConfigureAwait(false))
+        {
+            var cells = new object?[reader.FieldCount];
+            for (var i = 0; i < reader.FieldCount; i++)
+            {
+                cells[i] = reader.IsDBNull(i) ? null : reader.GetValue(i);
+            }
+
+            rows.Add(cells);
+        }
+
+        return (columns, rows);
+    }
+
+    private static void ApplyReadPragmas(SqliteConnection conn)
+    {
+        foreach (var pragma in new[]
+                 {
+                     "PRAGMA query_only = ON;",
+                     "PRAGMA foreign_keys = ON;",
+                     "PRAGMA busy_timeout = 5000;"
+                 })
+        {
+            using var cmd = conn.CreateCommand();
+            cmd.CommandText = pragma;
+            cmd.ExecuteNonQuery();
+        }
+    }
+
+    private static void ApplyWritePragmas(SqliteConnection conn)
+    {
+        foreach (var pragma in new[]
+                 {
+                     "PRAGMA foreign_keys = ON;",
+                     "PRAGMA busy_timeout = 5000;",
+                     "PRAGMA journal_mode = WAL;"
+                 })
+        {
+            using var cmd = conn.CreateCommand();
+            cmd.CommandText = pragma;
+            cmd.ExecuteNonQuery();
+        }
+    }
+}

src/Explorer.Storage.Sqlite/SqliteIndexStore.cs

@@ -592,6 +592,20 @@ public sealed class SqliteIndexStore : IIndexStore, IAsyncDisposable
             EnsureColumn(conn, "operation_profiles", "convert_kind", "TEXT NOT NULL DEFAULT 'VideoToMp4'");
             SetUserVersion(conn, 9);
             _logger.LogInformation("Migrated SQLite schema to v9 (conversion profiles)");
+            version = 9;
+        }
+
+        if (version < 10)
+        {
+            using (var idx = conn.CreateCommand())
+            {
+                idx.CommandText =
+                    "CREATE INDEX IF NOT EXISTS ix_hash_queue_state ON hash_queue(state, priority, size_bytes)";
+                idx.ExecuteNonQuery();
+            }
+
+            SetUserVersion(conn, 10);
+            _logger.LogInformation("Migrated SQLite schema to v10 (hash queue state index)");
         }
     }
 

tests/Explorer.Analysis.Tests/AnalysisTests.cs

@@ -178,10 +178,44 @@ public class AnalysisTests
         }
     }
 
+    [Fact]
+    public async Task Missing_files_are_tombstoned_when_loading_duplicates()
+    {
+        var (store, analysis, source) = await SeedHashedAsync(fileIdA: 1, fileIdB: 2);
+        await using (store)
+        {
+            File.Delete(Path.Combine(source.LastRootPath!, "a.bin"));
+            var classified = await analysis.GetClassifiedDuplicatesAsync();
+            Assert.Empty(classified);
+            var gone = await store.Entries.GetByPathAsync(source.Id, "a.bin");
+            Assert.Equal(EntryStatus.Deleted, gone!.Status);
+        }
+    }
+
+    [Fact]
+    public async Task Remaining_copies_still_show_when_one_duplicate_is_gone()
+    {
+        var (store, analysis, source) = await SeedHashedAsync(fileIdA: 1, fileIdB: 2);
+        await using (store)
+        {
+            File.WriteAllBytes(Path.Combine(source.LastRootPath!, "c.bin"), new byte[64]);
+            var root = await store.Entries.GetByPathAsync(source.Id, "");
+            await store.Entries.UpsertAsync(Hashed("c.bin", 3, source.Id, root!.Id, Enumerable.Repeat((byte)7, 32).ToArray()));
+            File.Delete(Path.Combine(source.LastRootPath!, "a.bin"));
+            var classified = Assert.Single(await analysis.GetClassifiedDuplicatesAsync());
+            Assert.Equal(2, classified.Group.Entries.Count);
+            Assert.DoesNotContain(classified.Group.Entries, e => e.PathRel == "a.bin");
+        }
+    }
+
     private static async Task<(SqliteIndexStore Store, AnalysisService Analysis, Source Source)> SeedHashedAsync(
         long fileIdA, long fileIdB)
     {
         var db = Path.Combine(Path.GetTempPath(), "ew-dup", Guid.NewGuid().ToString("N"), "index.db");
+        var rootPath = Path.Combine(Path.GetTempPath(), "ew-dup-fs", Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(rootPath);
+        File.WriteAllBytes(Path.Combine(rootPath, "a.bin"), new byte[64]);
+        File.WriteAllBytes(Path.Combine(rootPath, "b.bin"), new byte[64]);
         var store = new SqliteIndexStore(db, NullLogger<SqliteIndexStore>.Instance);
         await store.OpenAsync();
         var source = new Source
@@ -189,7 +223,7 @@ public class AnalysisTests
             StableKey = "d",
             DisplayName = "D",
             Kind = SourceKind.NtfsLocal,
-            LastRootPath = @"C:\d",
+            LastRootPath = rootPath,
             Status = SourceStatus.Online
         };
         source.Id = await store.Sources.UpsertAsync(source);

tests/Explorer.Application.Tests/HostActivityLogTests.cs

@@ -0,0 +1,31 @@
+using Explorer.Application;
+using Explorer.Contracts;
+
+namespace Explorer.Application.Tests;
+
+public class HostActivityLogTests
+{
+    [Fact]
+    public void Ring_keeps_recent_events_in_order()
+    {
+        var log = new HostActivityLog(8);
+        for (var i = 0; i < 10; i++)
+        {
+            log.Record("Indexing", "file-" + i);
+        }
+
+        var recent = log.TakeRecent(5);
+        Assert.Equal(5, recent.Count);
+        Assert.Equal("file-5", recent[0].Message);
+        Assert.Equal("file-9", recent[^1].Message);
+    }
+
+    [Fact]
+    public void Duplicate_messages_are_coalesced()
+    {
+        var log = new HostActivityLog();
+        log.Record("Maintenance", "same");
+        log.Record("Maintenance", "same");
+        Assert.Single(log.TakeRecent());
+    }
+}

tests/Explorer.Application.Tests/IndexedPathPresenceTests.cs

@@ -0,0 +1,85 @@
+using Explorer.Application;
+using Explorer.Domain;
+
+namespace Explorer.Application.Tests;
+
+public class IndexedPathPresenceTests
+{
+    [Fact]
+    public void Missing_tree_returns_the_highest_gone_folder()
+    {
+        var root = Path.Combine(Path.GetTempPath(), "ew-idx", Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(root);
+        try
+        {
+            Assert.Equal(
+                "gone",
+                IndexedPathPresence.HighestMissingPrefix(root, @"gone\deep\file.txt"));
+            Assert.Equal("nope.txt", IndexedPathPresence.HighestMissingPrefix(root, "nope.txt"));
+            File.WriteAllText(Path.Combine(root, "keep.txt"), "x");
+            Assert.Null(IndexedPathPresence.HighestMissingPrefix(root, "keep.txt"));
+        }
+        finally
+        {
+            Directory.Delete(root, true);
+        }
+    }
+
+    [Fact]
+    public void Archive_inner_path_follows_the_archive_file()
+    {
+        var root = Path.Combine(Path.GetTempPath(), "ew-idx", Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(root);
+        var zip = Path.Combine(root, "pack.zip");
+        File.WriteAllBytes(zip, [1, 2, 3]);
+        try
+        {
+            Assert.True(IndexedPathPresence.FileExists(root, @"pack.zip\inner.txt"));
+            File.Delete(zip);
+            Assert.False(IndexedPathPresence.FileExists(root, @"pack.zip\inner.txt"));
+            Assert.Equal("pack.zip", IndexedPathPresence.HighestMissingPrefix(root, @"pack.zip\inner.txt"));
+        }
+        finally
+        {
+            if (Directory.Exists(root))
+            {
+                Directory.Delete(root, true);
+            }
+        }
+    }
+
+    [Fact]
+    public void Reconcile_path_uses_the_parent_for_a_missing_file()
+    {
+        Assert.Equal("gone", IndexedPathPresence.ReconcilePath(@"gone\deep\file.txt", "gone"));
+        Assert.Equal("", IndexedPathPresence.ReconcilePath("nope.txt", "nope.txt"));
+        Assert.Equal("keep", IndexedPathPresence.ReconcilePath(@"keep\a.txt", @"keep\a.txt"));
+    }
+
+    [Fact]
+    public void Long_paths_are_detected_with_the_extended_prefix()
+    {
+        var root = Path.Combine(Path.GetTempPath(), "ew-idx", Guid.NewGuid().ToString("N"));
+        var relative = Path.Combine(new string('a', 140), new string('b', 140), "file.txt");
+        var full = PathRules.Combine(root, relative);
+        Directory.CreateDirectory(PathRules.ToExtended(PathRules.Parent(full)));
+        File.WriteAllText(PathRules.ToExtended(full), "x");
+        try
+        {
+            Assert.True(IndexedPathPresence.FileExists(root, relative));
+            File.Delete(PathRules.ToExtended(full));
+            Assert.False(IndexedPathPresence.FileExists(root, relative));
+        }
+        finally
+        {
+            try
+            {
+                Directory.Delete(PathRules.ToExtended(root), true);
+            }
+            catch
+            {
+                // ignore
+            }
+        }
+    }
+}

tests/Explorer.Domain.Tests/DomainTests.cs

@@ -299,6 +299,25 @@ public class DragDropPolicyTests
         Assert.False(DragDropPolicy.IsInvalidTarget([@"C:\Docs"], @"D:\Other"));
     }
 
+    [Fact]
+    public void Click_jitter_does_not_start_a_drag()
+    {
+        Assert.False(DragDropPolicy.ExceedsDistance(4, 3, DragDropPolicy.DragStartDistance));
+        Assert.False(DragDropPolicy.ExceedsDistance(12, 8, DragDropPolicy.DragStartDistance));
+        Assert.True(DragDropPolicy.ExceedsDistance(16, 0, DragDropPolicy.DragStartDistance));
+        Assert.True(DragDropPolicy.ExceedsDistance(12, 12, DragDropPolicy.DragStartDistance));
+    }
+
+    [Fact]
+    public void Same_folder_drop_is_redundant()
+    {
+        Assert.True(DragDropPolicy.AllAlreadyInDirectory([@"C:\Docs\a.txt", @"C:\Docs\b.txt"], @"C:\Docs"));
+        Assert.True(DragDropPolicy.AllAlreadyInDirectory([@"C:\Docs\a.txt"], @"C:\Docs\"));
+        Assert.False(DragDropPolicy.AllAlreadyInDirectory([@"C:\Docs\a.txt"], @"C:\Other"));
+        Assert.False(DragDropPolicy.AllAlreadyInDirectory([@"C:\Docs\a.txt", @"C:\Other\b.txt"], @"C:\Docs"));
+        Assert.False(DragDropPolicy.AllAlreadyInDirectory([], @"C:\Docs"));
+    }
+
     [Fact]
     public void Same_volume_uses_drive_or_unc_share()
     {

tests/Explorer.Hosting.Tests/BackgroundMaintenanceCoordinatorTests.cs

@@ -120,6 +120,21 @@ public class BackgroundMaintenanceCoordinatorTests
         Assert.Equal(new[] { 3L }, indexing.IdleVerifies);
     }
 
+    [Fact]
+    public async Task Run_now_keeps_running_while_user_stays_active()
+    {
+        var hash = new FakeHash();
+        var indexing = new FakeIndexing();
+        var coordinator = Create(hash, indexing, idle: TimeSpan.Zero, sources: [StaleLocal()]);
+        coordinator.RunNow();
+        await coordinator.TickAsync(CancellationToken.None);
+        Assert.Contains("checking", coordinator.Snapshot.Message, StringComparison.OrdinalIgnoreCase);
+
+        await coordinator.TickAsync(CancellationToken.None);
+        Assert.True(indexing.IdleAllowed);
+        Assert.DoesNotContain("Paused because user is active", coordinator.Snapshot.Message, StringComparison.Ordinal);
+    }
+
     [Fact]
     public async Task Idle_verifies_a_fresh_online_source()
     {
@@ -220,10 +235,12 @@ public class BackgroundMaintenanceCoordinatorTests
     {
         public bool Paused { get; set; } = true;
         public bool IsPaused => Paused;
+        public string? CurrentPath => null;
         public void Pause() => Paused = true;
         public void Resume() => Paused = false;
         public void BeginUserRequested() { }
         public Task<bool> HasPendingAsync(CancellationToken cancellationToken = default) => Task.FromResult(false);
+        public Task<long> CountPendingAsync(CancellationToken cancellationToken = default) => Task.FromResult(0L);
     }
 
     private sealed class FakeHistory : IHistoryMaintenance
@@ -303,6 +320,13 @@ public class BackgroundMaintenanceCoordinatorTests
         public Task<IReadOnlyList<DuplicateGroup>> GetDuplicateGroupsAsync(
             long? sourceId, string? pathPrefix, int take, CancellationToken cancellationToken = default)
             => Task.FromResult<IReadOnlyList<DuplicateGroup>>([]);
+        public Task<IReadOnlyList<byte[]>> GetDuplicateHashesAsync(
+            long? sourceId, string? pathPrefix, int take, CancellationToken cancellationToken = default)
+            => Task.FromResult<IReadOnlyList<byte[]>>([]);
+        public Task<IReadOnlyList<DuplicateGroup>> GetDuplicateGroupsByHashesAsync(
+            IReadOnlyList<byte[]> hashes, CancellationToken cancellationToken = default)
+            => Task.FromResult<IReadOnlyList<DuplicateGroup>>([]);
+        public Task<long> CountPendingAsync(CancellationToken cancellationToken = default) => Task.FromResult(0L);
     }
 
     private sealed class TempEnv : IAppEnvironment

tests/Explorer.Indexing.Tests/ScannerTests.cs

@@ -327,6 +327,30 @@ public class ScannerTests
         }
     }
 
+    [Fact]
+    public async Task Folder_reconcile_tombs_removed_directory_tree()
+    {
+        var root = CreateTree();
+        try
+        {
+            await using var store = await OpenStore();
+            var source = await AddSource(store, root);
+            var scanner = new FilesystemScanner(store, new IoEnumerator(), new StorageProviderRegistry([], NullLogger<StorageProviderRegistry>.Instance), NullLogger<FilesystemScanner>.Instance);
+            await scanner.ScanAsync(source, ScanKind.Full, null, null, CancellationToken.None);
+            Directory.Delete(Path.Combine(root, "Movies"), recursive: true);
+            var reconciler = new FolderReconciler(store, new IoEnumerator(), new StorageProviderRegistry([], NullLogger<StorageProviderRegistry>.Instance));
+            Assert.True(await reconciler.ReconcileAsync(source, "Movies", CancellationToken.None));
+            var folder = await store.Entries.GetByPathAsync(source.Id, "Movies");
+            var child = await store.Entries.GetByPathAsync(source.Id, @"Movies\b.txt");
+            Assert.Equal(EntryStatus.Deleted, folder!.Status);
+            Assert.Equal(EntryStatus.Deleted, child!.Status);
+        }
+        finally
+        {
+            TryDelete(root);
+        }
+    }
+
     [Fact]
     public async Task Folder_reconcile_tombs_removed_file()
     {

tests/Explorer.Storage.Tests/SqliteDatabaseSessionTests.cs

@@ -0,0 +1,51 @@
+using Explorer.Application;
+using Explorer.Storage.Sqlite;
+using Microsoft.Extensions.Logging.Abstractions;
+
+namespace Explorer.Storage.Tests;
+
+public class SqliteDatabaseSessionTests
+{
+    [Fact]
+    public async Task Can_browse_and_edit_a_standalone_database()
+    {
+        var dir = Path.Combine(Path.GetTempPath(), "ew-sql", Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(dir);
+        var path = Path.Combine(dir, "sample.db");
+        var indexPath = Path.Combine(dir, "index.db");
+        await using var writer = new SqliteIndexStore(indexPath, NullLogger<SqliteIndexStore>.Instance);
+        await writer.OpenAsync();
+        await writer.CloseAsync();
+
+        await using var session = new SqliteDatabaseSession(indexPath);
+        await session.OpenAsync(path, preferWrite: true);
+        Assert.True(session.CanWrite);
+        await session.ExecuteAsync("CREATE TABLE notes (id INTEGER PRIMARY KEY, body TEXT);");
+        await session.InsertRowAsync("notes", new Dictionary<string, object?> { ["body"] = "hello" });
+        var page = await session.ReadTableAsync("notes", 0, 50);
+        Assert.Contains("body", page.Columns);
+        Assert.Single(page.Rows);
+        var rowId = Convert.ToInt64(page.Rows[0][0]);
+        await session.UpdateCellAsync("notes", rowId, "body", "world");
+        var query = await session.ExecuteAsync("SELECT body FROM notes");
+        Assert.Equal("world", query.Rows[0][0]?.ToString());
+        await session.DeleteRowAsync("notes", rowId);
+        Assert.Equal(0, (await session.ReadTableAsync("notes", 0, 10)).TotalRows);
+    }
+
+    [Fact]
+    public async Task Index_opens_read_only_while_writer_holds_lock()
+    {
+        var dir = Path.Combine(Path.GetTempPath(), "ew-sql", Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(dir);
+        var path = Path.Combine(dir, "index.db");
+        await using var writer = new SqliteIndexStore(path, NullLogger<SqliteIndexStore>.Instance);
+        await writer.OpenAsync();
+        await using var session = new SqliteDatabaseSession(path);
+        await session.OpenAsync(path, preferWrite: true);
+        Assert.False(session.CanWrite);
+        Assert.Contains("Read-only", session.ModeLabel, StringComparison.OrdinalIgnoreCase);
+        var tables = await session.ListTablesAsync();
+        Assert.Contains("sources", tables);
+    }
+}