Show the currently processing file in the status line (v0.1.4)

The strip above the activity log used to echo the last completed log
line, so during a run it always trailed one file behind — misleading
when a multi-gigabyte file sits in the hasher for minutes. The engine
now raises an ItemStarted callback the moment an item begins hashing
(full-hash and incremental paths both), and the strip shows that
in-flight file as "» name" while a run is active. Completed items keep
flowing into the log below as before, and outside a run the strip
falls back to the last log line.

Worker threads only write a volatile field; the drawer's existing
150 ms timer publishes it to the UI, so even thousands of tiny items
per second cannot flood the UI thread.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: Eggmansworld

src/DatfileCreator.Core/DatEngine.cs

@@ -18,6 +18,8 @@ public sealed class EngineCallbacks
     public Action<string, int>? Folder { get; init; }
     /// <summary>Processing entered a new subfolder within the job (relative path).</summary>
     public Action<string>? Subfolder { get; init; }
+    /// <summary>Item processing started: (basename). Fires from worker threads.</summary>
+    public Action<string>? ItemStarted { get; init; }
     /// <summary>Item completed: (total done so far).</summary>
     public Action<int>? Progress { get; init; }
     /// <summary>Item hashed OK: (basename, diagnostic detail or "").</summary>
@@ -520,6 +522,7 @@ void EmitSubfolderMarker(string itemPath)
             // Returns (result-or-null, errorDetail-or-null)
             (object? Result, string? Error) SafeWork(string itemPath)
             {
+                cb.ItemStarted?.Invoke(Path.GetFileName(itemPath));
                 try
                 {
                     if (isMixed)

src/DatfileCreator.Core/IncrementalUpdate.cs

@@ -530,6 +530,7 @@ static long ParseSize(string? raw)
             string fname = Path.GetFileName(item);
             bool carried = false;
             string hashDiag = "";
+            cb.ItemStarted?.Invoke(fname);
             try
             {
                 if (isZipped)

src/DatfileCreatorStudio/DatfileCreatorStudio.csproj

@@ -9,7 +9,7 @@
         <AvaloniaUseCompiledBindingsByDefault>true</AvaloniaUseCompiledBindingsByDefault>
         <AssemblyName>DatfileCreatorStudio</AssemblyName>
         <RootNamespace>DatfileCreatorStudio</RootNamespace>
-        <Version>0.1.3</Version>
+        <Version>0.1.4</Version>
         <Authors>Eggman</Authors>
         <Product>Datfile Creator Studio</Product>
     </PropertyGroup>

src/DatfileCreatorStudio/ViewModels/LogDrawerViewModel.cs

@@ -64,6 +64,8 @@ public LogDrawerViewModel()
         _timer.Tick += (_, _) =>
         {
             FlushPending();
+            if (CurrentFile != _currentFilePending)
+                CurrentFile = _currentFilePending;
             if (_stopwatch.IsRunning)
                 Elapsed = _stopwatch.Elapsed.ToString(@"hh\:mm\:ss");
         };
@@ -74,14 +76,36 @@ public LogDrawerViewModel()
     private bool _isExpanded;
 
     [ObservableProperty]
+    [NotifyPropertyChangedFor(nameof(ActivityLine))]
     private bool _isRunning;
 
     [ObservableProperty]
     private string _statusText = "Idle";
 
     [ObservableProperty]
+    [NotifyPropertyChangedFor(nameof(ActivityLine))]
     private string _lastLine = "";
 
+    // ── Currently-processing file ────────────────────────────────────────
+    // Worker threads report every item as it STARTS via SetCurrentFile; the
+    // 150 ms timer publishes the latest value on the UI thread, so the strip
+    // shows what is being hashed right now (a big zip can sit here for
+    // minutes) while completed items keep flowing into the log as before.
+
+    /// <summary>Written from engine worker threads; read by the UI timer.</summary>
+    private volatile string _currentFilePending = "";
+
+    [ObservableProperty]
+    [NotifyPropertyChangedFor(nameof(ActivityLine))]
+    private string _currentFile = "";
+
+    /// <summary>Thread-safe: record the item whose processing just began.</summary>
+    public void SetCurrentFile(string name) => _currentFilePending = name;
+
+    /// <summary>The strip's activity text: in-flight file while running, last log line otherwise.</summary>
+    public string ActivityLine =>
+        IsRunning && CurrentFile.Length > 0 ? "» " + CurrentFile : LastLine;
+
     [ObservableProperty]
     private string _elapsed = "";
 
@@ -126,6 +150,8 @@ public void OnRunStarted(string summary)
     {
         Append(LogKind.Info, "");
         Append(LogKind.Phase, "> " + summary);
+        _currentFilePending = "";
+        CurrentFile = "";
         IsRunning = true;
         IsExpanded = true;
         StatusText = "Running";
@@ -162,6 +188,8 @@ public void OnRunCompleted(bool ok, int errorCount, bool stopped)
         Elapsed = _stopwatch.Elapsed.ToString(@"hh\:mm\:ss");
         IsRunning = false;
         IsIndeterminate = false;
+        _currentFilePending = "";
+        CurrentFile = "";
 
         (StatusText, StatusBrush) = (stopped, ok, errorCount) switch
         {

src/DatfileCreatorStudio/ViewModels/MainWindowViewModel.cs

@@ -434,6 +434,7 @@ private async Task StartAsync()
                 if (rel is not ("." or ""))
                     Drawer.Append(LogKind.Subfolder, "   [dir] " + rel);
             },
+            ItemStarted = name => Drawer.SetCurrentFile(name),
             Progress = done =>
                 Dispatcher.UIThread.Post(() => Drawer.OnProgress(done)),
             ItemHashed = (name, detail) =>

src/DatfileCreatorStudio/Views/Controls/LogDrawer.axaml

@@ -36,10 +36,11 @@
                 <TextBlock Grid.Column="4" Text="{Binding ItemsText}" FontSize="12"
                            Foreground="{DynamicResource AppSubtleTextBrush}"
                            VerticalAlignment="Center" Margin="0,0,16,0"/>
-                <TextBlock Grid.Column="5" Text="{Binding LastLine}" FontSize="12"
+                <TextBlock Grid.Column="5" Text="{Binding ActivityLine}" FontSize="12"
                            FontFamily="Cascadia Mono,Consolas,DejaVu Sans Mono,Liberation Mono,monospace"
                            Foreground="{DynamicResource AppSubtleTextBrush}"
-                           TextTrimming="CharacterEllipsis" VerticalAlignment="Center" Margin="0,0,12,0"/>
+                           TextTrimming="CharacterEllipsis" VerticalAlignment="Center" Margin="0,0,12,0"
+                           ToolTip.Tip="While a run is active this shows the file being processed right now; completed items scroll into the log below"/>
 
                 <Button Grid.Column="6" Classes="icon" Click="OnCopyLogClick"
                         ToolTip.Tip="Copy the full log to the clipboard" VerticalAlignment="Center">