feat(ui): route command exceptions through report+log pipe

Docs/architecture/error-reporting.md

@@ -46,8 +46,28 @@ read `Errors[0]` directly.
   discrete one-shot channel. `RecipeCoordinator` bridges each fault to the operation channel via
   `ReportError(error.Message)` — the message text is owned in Core. The persistent "disconnected"
   label stays in the status bar.
-- **Exception handlers** (`ReportError($"... {ex.Message}")` on `ThrownExceptions`) are not
-  `Result`-based and stay as-is.
+- **Command exceptions** (a `ReactiveCommand` fault on `ThrownExceptions`) are not `Result`-based;
+  they route through `ReportThrownExceptions` (see below) rather than a hand-written handler.
 - **One deliberate exception** to the `"; "` idiom: the clipboard *paste* failure lists each error on
   its own line (`Environment.NewLine`), because a rejected paste can carry many per-step errors that
   read better stacked. It still surfaces every error (never just `Errors[0]`).
+
+## Command-exception pipe (report + log)
+
+A command whose `Execute` throws (file I/O, PLC calls) faults on `ReactiveCommand.ThrownExceptions`.
+These faults route through one extension:
+
+- `IDisposable ReportThrownExceptions<TParam, TResult>(this ReactiveCommand<TParam, TResult>, MessagePanelViewModel panel, ILogger logger, string context)`
+  (`SemiStep.UI/MessageService/ReactiveCommandReportingExtensions.cs`). Per thrown exception it both
+  `logger.LogError(ex, "{Context} failed", context)` **and** `panel.ReportError($"{context}: {ex.Message}")`.
+  The panel keeps the user-facing message it always showed; the log now carries the exception type and
+  full stack that the message drops.
+
+The `logger` argument is the caller's own `ILogger<TVm>`, so the Serilog `{SourceContext}` field names
+the originating view model in every logged fault. The extension takes the concrete
+`MessagePanelViewModel`, not an `IMessageSink` abstraction — one panel implementation exists, so the
+seam stays concrete (matches `ResultReportingExtensions`).
+
+Modal dialogs are the exception: `GridStyleEditorViewModel.SaveCommand` surfaces its fault on the
+editor's own `ErrorMessage` property (and logs), not the shared panel, because a modal owns its error
+surface while it is open.

Docs/architecture/headless-ui-testing.md

@@ -17,8 +17,8 @@ stand-in. See `SemiStep.Tests/UI/MainWindow/MainWindowExitFlowTests.cs` for a wo
 `RunJobs` remains necessary only to pump work the test never awaits:
 
 - fire-and-forget `async void` continuations (e.g. a `Closing` event handler that awaits a dialog);
-- `ObserveOn(RxApp.MainThreadScheduler)` deliveries, such as `ThrownExceptions` reports posted to
-  the message panel.
+- `ObserveOn(RxApp.MainThreadScheduler)` deliveries, such as the `MainWindowViewModel` sync-time
+  `Observable.Interval` tick that reposts `LastSyncTimeText` on the UI scheduler.
 
 Call `Dispatcher.UIThread.RunJobs()` after triggering such work and before asserting on its effect.
 

SemiStep/SemiStep.Core/Configuration/GridStyleEditorFacade.cs

@@ -12,7 +12,7 @@ namespace SemiStep.Core.Configuration;
 /// row height, spacing, panel height) is the caller's responsibility — the editor view model enforces
 /// those bounds before invoking <see cref="Save"/>.
 /// </summary>
-public sealed class GridStyleEditorFacade
+public sealed class GridStyleEditorFacade : IGridStyleEditorFacade
 {
 	private readonly GridStyleWriter _gridStyleWriter = new();
 

SemiStep/SemiStep.Core/Configuration/IGridStyleEditorFacade.cs

@@ -0,0 +1,16 @@
+using FluentResults;
+
+namespace SemiStep.Core.Configuration;
+
+/// <summary>
+/// The style-editor seam consumed by the UI editor view model. Declared as an interface so the
+/// view model depends on an abstraction it can mock, rather than the concrete Core facade.
+/// </summary>
+public interface IGridStyleEditorFacade
+{
+	Task<Result<GridStyleOptions>> Load(string configDir);
+
+	Result Validate(GridStyleOptions options);
+
+	Result Save(string configDir, GridStyleOptions options);
+}

SemiStep/SemiStep.Tests/UI/Clipboard/ClipboardViewModelCanExecuteTests.cs

@@ -4,6 +4,8 @@
 
 using FluentAssertions;
 
+using Microsoft.Extensions.Logging.Abstractions;
+
 using SemiStep.Core.Recipes.Clipboard;
 using SemiStep.Core.Recipes.Helpers;
 using SemiStep.Tests.Core.Helpers;
@@ -39,7 +41,8 @@ public async ValueTask InitializeAsync()
 			_surface,
 			clipboardSerializer,
 			importedRecipeValidator,
-			_fixture.MessagePanel);
+			_fixture.MessagePanel,
+			NullLogger<ClipboardViewModel>.Instance);
 	}
 
 	public async ValueTask DisposeAsync()
@@ -113,7 +116,8 @@ public void Cut_CanExecuteTrue_WhenSelectionExistsBeforeConstruction()
 			_surface,
 			new ClipboardSerializer(_fixture.RecipeMetadataRegistry),
 			new ImportedRecipeValidator(_fixture.RecipeMetadataRegistry),
-			_fixture.MessagePanel);
+			_fixture.MessagePanel,
+			NullLogger<ClipboardViewModel>.Instance);
 
 		((ICommand)clipboard.CutStepCommand).CanExecute(null).Should().BeTrue();
 	}

SemiStep/SemiStep.Tests/UI/Helpers/UIFixture.cs

@@ -140,7 +140,8 @@ public void SeedRecipe(int stepCount)
 	}
 
 	public MainWindowViewModel CreateMainWindowViewModel(
-		Func<GridStyleEditorViewModel>? styleEditorFactory = null)
+		Func<GridStyleEditorViewModel>? styleEditorFactory = null,
+		ILogger<MainWindowViewModel>? logger = null)
 	{
 		var grid = CreateActiveSurface();
 
@@ -153,9 +154,13 @@ public MainWindowViewModel CreateMainWindowViewModel(
 			grid,
 			clipboardSerializer,
 			importedRecipeValidator,
-			MessagePanel);
+			MessagePanel,
+			NullLogger<ClipboardViewModel>.Instance);
 
-		var recipeFile = new RecipeFileViewModel(Coordinator, MessagePanel);
+		var recipeFile = new RecipeFileViewModel(
+			Coordinator,
+			MessagePanel,
+			NullLogger<RecipeFileViewModel>.Instance);
 
 		var plcMonitor = new PlcMonitorViewModel(
 			Coordinator,
@@ -166,7 +171,8 @@ public MainWindowViewModel CreateMainWindowViewModel(
 			() => new GridStyleEditorViewModel(
 				new GridStyleEditorFacade(),
 				@"C:\does-not-exist",
-				AppConfiguration.GridStyle));
+				AppConfiguration.GridStyle,
+				NullLogger<GridStyleEditorViewModel>.Instance));
 
 		return new MainWindowViewModel(
 			Coordinator,
@@ -177,7 +183,7 @@ public MainWindowViewModel CreateMainWindowViewModel(
 			MessagePanel,
 			plcMonitor,
 			gridStyleEditorViewModelFactory,
-			NullLogger<MainWindowViewModel>.Instance);
+			logger ?? NullLogger<MainWindowViewModel>.Instance);
 	}
 
 	public void SetSyncEnabled(bool isSyncEnabled)

SemiStep/SemiStep.Tests/UI/MainWindow/MainWindowViewModelReportingTests.cs

@@ -0,0 +1,73 @@
+using System;
+
+using Avalonia.Headless.XUnit;
+
+using FluentAssertions;
+
+using Microsoft.Extensions.Logging;
+
+using SemiStep.Tests.Helpers;
+using SemiStep.Tests.UI.Helpers;
+using SemiStep.UI.MainWindow;
+using SemiStep.UI.MessageService;
+
+using Xunit;
+
+namespace SemiStep.Tests.UI.MainWindow;
+
+[Trait("Component", "UI")]
+[Trait("Area", "MessageReporting")]
+[Trait("Category", "Unit")]
+public sealed class MainWindowViewModelReportingTests : IAsyncLifetime
+{
+	private readonly UIFixture _fixture = new();
+	private readonly RecordingLogger<MainWindowViewModel> _logger = new();
+	private MainWindowViewModel _viewModel = null!;
+
+	public async ValueTask InitializeAsync()
+	{
+		await _fixture.InitializeAsync();
+		_viewModel = _fixture.CreateMainWindowViewModel(logger: _logger);
+	}
+
+	public ValueTask DisposeAsync()
+	{
+		_viewModel.Dispose();
+		return _fixture.DisposeAsync();
+	}
+
+	[AvaloniaTheory]
+	[InlineData("PLC state update")]
+	[InlineData("PLC conflict handling")]
+	[InlineData("Sync time refresh")]
+	public void OnSubscriptionError_ReportsToPanelAndLogsException(string context)
+	{
+		var failure = new InvalidOperationException("boom");
+
+		_viewModel.OnSubscriptionError(context)(failure);
+
+		_fixture.MessagePanel.Entries.Should().ContainSingle(
+			entry => entry.Severity == MessageSeverity.Error && entry.Message == $"{context}: boom");
+
+		var logged = _logger.Entries.Should().ContainSingle().Subject;
+		logged.Level.Should().Be(LogLevel.Error);
+		logged.Exception.Should().BeSameAs(failure);
+	}
+
+	[AvaloniaFact]
+	public void Guarded_ThrowInOnNextBody_ReportsToPanelAndLogs_WithoutEscaping()
+	{
+		var failure = new InvalidOperationException("boom");
+
+		var act = () => _viewModel.Guarded("Sync time refresh", () => throw failure);
+
+		act.Should().NotThrow("a throw in the onNext body must be contained, not propagated to the pipeline");
+
+		_fixture.MessagePanel.Entries.Should().ContainSingle(
+			entry => entry.Severity == MessageSeverity.Error && entry.Message == "Sync time refresh: boom");
+
+		var logged = _logger.Entries.Should().ContainSingle().Subject;
+		logged.Level.Should().Be(LogLevel.Error);
+		logged.Exception.Should().BeSameAs(failure);
+	}
+}

SemiStep/SemiStep.Tests/UI/MessagePanelReportingTests.cs

@@ -7,6 +7,8 @@
 
 using FluentAssertions;
 
+using Microsoft.Extensions.Logging.Abstractions;
+
 using ReactiveUI;
 
 using SemiStep.Core.Recipes.Clipboard;
@@ -47,7 +49,10 @@ public async ValueTask DisposeAsync()
 	[AvaloniaFact]
 	public async Task RecipeFile_Save_ReportsSuccess()
 	{
-		var recipeFile = new RecipeFileViewModel(_fixture.Coordinator, _fixture.MessagePanel);
+		var recipeFile = new RecipeFileViewModel(
+			_fixture.Coordinator,
+			_fixture.MessagePanel,
+			NullLogger<RecipeFileViewModel>.Instance);
 		var filePath = Path.Combine(Path.GetTempPath(), $"semistep-save-{Guid.NewGuid():N}.csv");
 		recipeFile.SaveFileInteraction.RegisterHandler(context => context.SetOutput(filePath));
 
@@ -69,7 +74,10 @@ public async Task RecipeFile_Save_ReportsSuccess()
 	[AvaloniaFact]
 	public async Task RecipeFile_Load_ReportsSuccess()
 	{
-		var recipeFile = new RecipeFileViewModel(_fixture.Coordinator, _fixture.MessagePanel);
+		var recipeFile = new RecipeFileViewModel(
+			_fixture.Coordinator,
+			_fixture.MessagePanel,
+			NullLogger<RecipeFileViewModel>.Instance);
 		var filePath = Path.Combine(Path.GetTempPath(), $"semistep-load-{Guid.NewGuid():N}.csv");
 		recipeFile.SaveFileInteraction.RegisterHandler(context => context.SetOutput(filePath));
 		recipeFile.OpenFileInteraction.RegisterHandler(context => context.SetOutput(filePath));
@@ -94,7 +102,10 @@ public async Task RecipeFile_Load_ReportsSuccess()
 	[AvaloniaFact]
 	public async Task RecipeFile_LoadMissingFile_ReportsError()
 	{
-		var recipeFile = new RecipeFileViewModel(_fixture.Coordinator, _fixture.MessagePanel);
+		var recipeFile = new RecipeFileViewModel(
+			_fixture.Coordinator,
+			_fixture.MessagePanel,
+			NullLogger<RecipeFileViewModel>.Instance);
 		var missingPath = Path.Combine(Path.GetTempPath(), $"semistep-missing-{Guid.NewGuid():N}.csv");
 		recipeFile.OpenFileInteraction.RegisterHandler(context => context.SetOutput(missingPath));
 
@@ -149,7 +160,8 @@ public async Task Clipboard_PasteInvalidContent_ReportsError()
 			_surface,
 			clipboardSerializer,
 			importedRecipeValidator,
-			_fixture.MessagePanel);
+			_fixture.MessagePanel,
+			NullLogger<ClipboardViewModel>.Instance);
 
 		var window = new Window();
 		window.Show();
@@ -187,7 +199,8 @@ public async Task Clipboard_PasteValidContent_LeavesNoOperationError()
 			_surface,
 			clipboardSerializer,
 			importedRecipeValidator,
-			_fixture.MessagePanel);
+			_fixture.MessagePanel,
+			NullLogger<ClipboardViewModel>.Instance);
 
 		var window = new Window();
 		window.Show();

SemiStep/SemiStep.Tests/UI/MessageService/ReactiveCommandReportingExtensionsTests.cs

@@ -0,0 +1,88 @@
+using System;
+using System.Reactive;
+using System.Reactive.Linq;
+
+using Avalonia.Headless.XUnit;
+
+using FluentAssertions;
+
+using Microsoft.Extensions.Logging;
+
+using ReactiveUI;
+
+using SemiStep.Tests.Helpers;
+using SemiStep.UI.MessageService;
+
+using Xunit;
+
+namespace SemiStep.Tests.UI.MessageService;
+
+[Trait("Component", "UI")]
+[Trait("Area", "MessageReporting")]
+[Trait("Category", "Unit")]
+public sealed class ReactiveCommandReportingExtensionsTests
+{
+	[AvaloniaFact]
+	public async Task ReportThrownExceptions_ThrowingCommand_ReportsSinglePanelErrorAndLogsException()
+	{
+		var panel = new MessagePanelViewModel();
+		var logger = new RecordingLogger<object>();
+		var failure = new InvalidOperationException("boom");
+		var command = ReactiveCommand.Create<Unit, Unit>(_ => throw failure);
+
+		using var subscription = command.ReportThrownExceptions(panel, logger, "Copy failed");
+
+		try
+		{
+			await ExecuteSwallowing(command);
+
+			var entry = panel.Entries.Should().ContainSingle().Subject;
+			entry.Severity.Should().Be(MessageSeverity.Error);
+			entry.Message.Should().Be("Copy failed: boom");
+
+			var logged = logger.Entries.Should().ContainSingle().Subject;
+			logged.Level.Should().Be(LogLevel.Error);
+			logged.Exception.Should().BeSameAs(failure);
+		}
+		finally
+		{
+			command.Dispose();
+			panel.Dispose();
+		}
+	}
+
+	[AvaloniaFact]
+	public async Task ReportThrownExceptions_NonThrowingCommand_ProducesNoPanelEntryAndNoLog()
+	{
+		var panel = new MessagePanelViewModel();
+		var logger = new RecordingLogger<object>();
+		var command = ReactiveCommand.Create<Unit, Unit>(_ => Unit.Default);
+
+		using var subscription = command.ReportThrownExceptions(panel, logger, "Copy failed");
+
+		try
+		{
+			await command.Execute();
+
+			panel.Entries.Should().BeEmpty();
+			logger.Entries.Should().BeEmpty();
+		}
+		finally
+		{
+			command.Dispose();
+			panel.Dispose();
+		}
+	}
+
+	private static async Task ExecuteSwallowing(ReactiveCommand<Unit, Unit> command)
+	{
+		try
+		{
+			await command.Execute();
+		}
+		catch (InvalidOperationException)
+		{
+			// The command routes the throw to ThrownExceptions; Execute also rethrows to the awaiter.
+		}
+	}
+}

SemiStep/SemiStep.Tests/UI/RecipeFile/RecipeFileViewModelCanExecuteTests.cs

@@ -4,6 +4,8 @@
 
 using FluentAssertions;
 
+using Microsoft.Extensions.Logging.Abstractions;
+
 using SemiStep.Tests.UI.Helpers;
 
 using SemiStep.UI.RecipeFile;
@@ -23,7 +25,10 @@ public sealed class RecipeFileViewModelCanExecuteTests : IAsyncLifetime
 	public async ValueTask InitializeAsync()
 	{
 		await _fixture.InitializeAsync();
-		_recipeFile = new RecipeFileViewModel(_fixture.Coordinator, _fixture.MessagePanel);
+		_recipeFile = new RecipeFileViewModel(
+			_fixture.Coordinator,
+			_fixture.MessagePanel,
+			NullLogger<RecipeFileViewModel>.Instance);
 	}
 
 	public async ValueTask DisposeAsync()