From a214719ba1ec34d5e4f7db56fd344e0464ad20bb Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 06:42:16 +0700
Subject: [PATCH 01/84] FAT M1: remove duplicate late navigation parity owner

---
 MainWindow.ProductionFatNavigationParity.cs | 173 --------------------
 1 file changed, 173 deletions(-)
 delete mode 100644 MainWindow.ProductionFatNavigationParity.cs

diff --git a/MainWindow.ProductionFatNavigationParity.cs b/MainWindow.ProductionFatNavigationParity.cs
deleted file mode 100644
index 61787678d..000000000
--- a/MainWindow.ProductionFatNavigationParity.cs
+++ /dev/null
@@ -1,173 +0,0 @@
-using System.Runtime.CompilerServices;
-using System.Windows;
-using System.Windows.Controls;
-using System.Windows.Media;
-using System.Windows.Media.Animation;
-using System.Windows.Threading;
-
-namespace ArIED61850Tester;
-
-/// <summary>
-/// Extends the existing six-destination responsive nav contract to the dynamically-added
-/// production FAT destination. The legacy MainWindow navigation code clamps index 6 to 5;
-/// this late correction keeps Diagnostics from remaining highlighted while FAT is active
-/// and moves the same selection pill into the seventh equal-width cell.
-/// </summary>
-internal static class MainWindowProductionFatNavigationParity
-{
-    private static readonly string[] NavigationButtonNames =
-    [
-        "NavExplorerButton",
-        "NavLiveButton",
-        "NavEventsButton",
-        "NavAlarmButton",
-        "NavGooseButton",
-        "NavDiagnosticsButton",
-        "NavNativeFatButton"
-    ];
-
-    [ModuleInitializer]
-    internal static void Register()
-    {
-        EventManager.RegisterClassHandler(
-            typeof(MainWindow),
-            FrameworkElement.LoadedEvent,
-            new RoutedEventHandler(OnLoaded),
-            handledEventsToo: true);
-        EventManager.RegisterClassHandler(
-            typeof(MainWindow),
-            Button.ClickEvent,
-            new RoutedEventHandler(OnButtonClick),
-            handledEventsToo: true);
-    }
-
-    private static void OnLoaded(object sender, RoutedEventArgs e)
-    {
-        if (sender is not MainWindow window)
-            return;
-
-        window.SizeChanged -= Window_SizeChanged;
-        window.SizeChanged += Window_SizeChanged;
-        if (window.FindName("MainTabs") is TabControl tabs)
-        {
-            tabs.SelectionChanged -= Tabs_SelectionChanged;
-            tabs.SelectionChanged += Tabs_SelectionChanged;
-        }
-        Queue(window, animate: false);
-    }
-
-    private static void OnButtonClick(object sender, RoutedEventArgs e)
-    {
-        if (sender is not MainWindow window || e.Source is not Button button ||
-            !NavigationButtonNames.Contains(button.Name, StringComparer.Ordinal))
-        {
-            return;
-        }
-        Queue(window, animate: true);
-    }
-
-    private static void Tabs_SelectionChanged(object sender, SelectionChangedEventArgs e)
-    {
-        if (sender is not TabControl tabs || !ReferenceEquals(e.Source, tabs) ||
-            Window.GetWindow(tabs) is not MainWindow window)
-        {
-            return;
-        }
-        Queue(window, animate: true);
-    }
-
-    private static void Window_SizeChanged(object sender, SizeChangedEventArgs e)
-    {
-        if (sender is MainWindow window)
-            Queue(window, animate: false);
-    }
-
-    private static void Queue(MainWindow window, bool animate)
-    {
-        // Existing MainWindow + responsive-layout handlers still perform their historical
-        // six-slot correction. ApplicationIdle deliberately runs after those handlers so
-        // the seven-slot Engineering shell is the final visual authority.
-        window.Dispatcher.BeginInvoke(
-            DispatcherPriority.ApplicationIdle,
-            new Action(() => Apply(window, animate)));
-    }
-
-    private static void Apply(MainWindow window, bool animate)
-    {
-        if (window.FindName("MainTabs") is not TabControl tabs || tabs.Items.Count < 7 ||
-            window.FindName("WorkflowNavGrid") is not Grid grid ||
-            window.FindName("WorkflowNavShell") is not Border shell ||
-            window.FindName("WorkflowPill") is not Border pill)
-        {
-            return;
-        }
-
-        var fatButton = grid.Children
-            .OfType<Button>()
-            .FirstOrDefault(button => button.Name.Equals("NavNativeFatButton", StringComparison.Ordinal));
-        var buttons = new Button?[]
-        {
-            window.FindName("NavExplorerButton") as Button,
-            window.FindName("NavLiveButton") as Button,
-            window.FindName("NavEventsButton") as Button,
-            window.FindName("NavAlarmButton") as Button,
-            window.FindName("NavGooseButton") as Button,
-            window.FindName("NavDiagnosticsButton") as Button,
-            fatButton
-        };
-        if (buttons.Any(button => button == null))
-            return;
-
-        while (grid.ColumnDefinitions.Count < 7)
-            grid.ColumnDefinitions.Add(new ColumnDefinition());
-        foreach (var column in grid.ColumnDefinitions.Take(7))
-            column.Width = new GridLength(1, GridUnitType.Star);
-
-        // FAT must use the exact same button style and density as its siblings.
-        var reference = buttons[5]!;
-        var muted = window.TryFindResource("Muted") as Brush ?? new SolidColorBrush(Color.FromRgb(0x5F, 0x6B, 0x7A));
-        var selectedIndex = Math.Clamp(tabs.SelectedIndex, 0, 6);
-        for (var index = 0; index < buttons.Length; index++)
-        {
-            var button = buttons[index]!;
-            button.Style ??= reference.Style;
-            button.MinHeight = reference.MinHeight;
-            button.MinWidth = 0;
-            button.Margin = reference.Margin;
-            button.Padding = reference.Padding;
-            button.HorizontalContentAlignment = reference.HorizontalContentAlignment;
-            button.VerticalAlignment = reference.VerticalAlignment;
-            button.VerticalContentAlignment = reference.VerticalContentAlignment;
-            button.Foreground = index == selectedIndex ? Brushes.White : muted;
-        }
-
-        var contentWidth = Math.Max(0d, shell.ActualWidth - shell.Padding.Left - shell.Padding.Right);
-        if (contentWidth <= 0d)
-            contentWidth = Math.Max(0d, shell.Width - shell.Padding.Left - shell.Padding.Right);
-        var cellWidth = contentWidth / 7d;
-        pill.Width = Math.Max(1d, cellWidth - 2d);
-        pill.Height = 36;
-
-        var translate = window.FindName("WorkflowPillTranslate") as TranslateTransform;
-        if (translate == null && pill.RenderTransform is TransformGroup group)
-            translate = group.Children.OfType<TranslateTransform>().LastOrDefault();
-        if (translate == null)
-            return;
-
-        var target = selectedIndex * cellWidth;
-        translate.BeginAnimation(TranslateTransform.XProperty, null);
-        if (!animate)
-        {
-            translate.X = target;
-            return;
-        }
-
-        translate.BeginAnimation(
-            TranslateTransform.XProperty,
-            new DoubleAnimation(target, TimeSpan.FromMilliseconds(190))
-            {
-                EasingFunction = new CubicEase { EasingMode = EasingMode.EaseOut },
-                FillBehavior = FillBehavior.HoldEnd
-            });
-    }
-}

From c6a856ed764c6a65294cd652925d111e41497714 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 06:42:30 +0700
Subject: [PATCH 02/84] FAT M0: lock engineering authority and navigation
 regression contract

---
 ...ductionFatEngineeringTabRegressionTests.cs | 47 +++++++++++++------
 1 file changed, 33 insertions(+), 14 deletions(-)

diff --git a/tests/ARSAS.Tests/ProductionFatEngineeringTabRegressionTests.cs b/tests/ARSAS.Tests/ProductionFatEngineeringTabRegressionTests.cs
index 46509c39d..2f6f94ec2 100644
--- a/tests/ARSAS.Tests/ProductionFatEngineeringTabRegressionTests.cs
+++ b/tests/ARSAS.Tests/ProductionFatEngineeringTabRegressionTests.cs
@@ -44,31 +44,50 @@ public void ProductionFatTab_RegistersExactEngineeringRuntimeWorkspacesForShared
     }
 
     [Fact]
-    public void SeventhFatDestination_UsesSameSelectionPillAndActiveForegroundContract()
+    public void SeventhFatDestination_HasOnlyOneSevenSlotCompatibilityOwner()
     {
-        var source = File.ReadAllText(FindRepoFile("MainWindow.ProductionFatNavigationParity.cs"));
+        var nativeSource = File.ReadAllText(FindRepoFile("MainWindow.NativeFatWorkspace.cs"));
+        var repoRoot = FindRepoRoot();
 
-        Assert.Contains("NavNativeFatButton", source, StringComparison.Ordinal);
-        Assert.Contains("buttons.Length", source, StringComparison.Ordinal);
-        Assert.Contains("Math.Clamp(tabs.SelectedIndex, 0, 6)", source, StringComparison.Ordinal);
-        Assert.Contains("var cellWidth = contentWidth / 7d", source, StringComparison.Ordinal);
-        Assert.Contains("pill.Width = Math.Max(1d, cellWidth - 2d)", source, StringComparison.Ordinal);
-        Assert.Contains("button.Foreground = index == selectedIndex ? Brushes.White : muted", source, StringComparison.Ordinal);
-        Assert.Contains("DispatcherPriority.ApplicationIdle", source, StringComparison.Ordinal);
+        Assert.Contains("NavNativeFatButton", nativeSource, StringComparison.Ordinal);
+        Assert.Contains("TryFindResource(\"SegmentedNavButton\")", nativeSource, StringComparison.Ordinal);
+        Assert.Contains("var cellWidth = contentWidth / 7d", nativeSource, StringComparison.Ordinal);
+        Assert.Contains("Math.Clamp(MainTabs.SelectedIndex, 0, NativeFatWorkspaceIndex)", nativeSource, StringComparison.Ordinal);
+        Assert.False(
+            File.Exists(Path.Combine(repoRoot, "MainWindow.ProductionFatNavigationParity.cs")),
+            "Do not reintroduce a second ApplicationIdle navigation parity owner. Seven-slot navigation must converge toward one canonical owner.");
+    }
+
+    [Fact]
+    public void ProductionFatSafetyBoundary_KeepsEngineeringAuthorityAndStrictPreflightCoverage()
+    {
+        var bootstrapSource = File.ReadAllText(FindRepoFile("MainWindow.ProductionFatEngineeringBootstrap.cs"));
+        var fieldRegressionSource = File.ReadAllText(FindRepoFile("tests/ARSAS.Tests/ProductionFatP0FieldRegressionTests.cs"));
+
+        Assert.Contains("RetireManualWorkspaceRowsForStaticDataSetMode", bootstrapSource, StringComparison.Ordinal);
+        Assert.Contains("AutomaticStaticDataSetScope_RetiresManualAliasBeforeSessionPreflight", fieldRegressionSource, StringComparison.Ordinal);
+        Assert.Contains("IoTestSessionPreflight.Validate", fieldRegressionSource, StringComparison.Ordinal);
+        Assert.Contains("multiple enabled test points", fieldRegressionSource, StringComparison.OrdinalIgnoreCase);
     }
 
     private static string FindRepoFile(string relativePath)
+        => Path.Combine(FindRepoRoot(), relativePath);
+
+    private static string FindRepoRoot()
     {
         DirectoryInfo? directory = new(AppContext.BaseDirectory);
         while (directory != null)
         {
-            var candidate = Path.Combine(directory.FullName, relativePath);
-            if (File.Exists(candidate))
-                return candidate;
+            if (File.Exists(Path.Combine(directory.FullName, "MainWindow.xaml")) &&
+                Directory.Exists(Path.Combine(directory.FullName, "tests", "ARSAS.Tests")))
+            {
+                return directory.FullName;
+            }
+
             directory = directory.Parent;
         }
 
-        throw new FileNotFoundException(
-            $"Could not locate repository file '{relativePath}' from '{AppContext.BaseDirectory}'.");
+        throw new DirectoryNotFoundException(
+            $"Could not locate repository root from '{AppContext.BaseDirectory}'.");
     }
 }

From ee1b83b28a64678c389c6ddbb202977045c71bd5 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 06:42:51 +0700
Subject: [PATCH 03/84] FAT M0: freeze Engineering workstation architecture
 contract

---
 docs/FAT_ENGINEERING_WORKSTATION_CONTRACT.md | 100 +++++++++++++++++++
 1 file changed, 100 insertions(+)
 create mode 100644 docs/FAT_ENGINEERING_WORKSTATION_CONTRACT.md

diff --git a/docs/FAT_ENGINEERING_WORKSTATION_CONTRACT.md b/docs/FAT_ENGINEERING_WORKSTATION_CONTRACT.md
new file mode 100644
index 000000000..63217aceb
--- /dev/null
+++ b/docs/FAT_ENGINEERING_WORKSTATION_CONTRACT.md
@@ -0,0 +1,100 @@
+# ARSAS FAT Engineering Workstation Contract
+
+This document is the architectural freeze for the Engineering-integrated FAT workflow. Changes that violate these invariants must not be merged, even if a visual patch appears to fix one field symptom.
+
+## Ownership
+
+- `MainWindow` owns the persistent Engineering workstation shell, navigation, global IED Explorer, and shared Command Dock.
+- Engineering owns IEC 61850 device identity, `SelectedDevice`, parsed `SclIedWorkspace`, static DataSet selection, live signal definitions, live points, MMS/report acquisition, and connection lifecycle.
+- The production FAT controller owns FAT preflight, session lifecycle, capture semantics, V1/V2 evidence, completion/result semantics, and FAT persistence.
+- FAT presentation must not own a second IEC 61850 parser, discovery session, MMS connection, live polling loop, or command runtime.
+- Report presentation must reuse the production FAT report definition; preview and PDF/print must not diverge into separate report models.
+
+## Primary user flow
+
+`Open SCL -> Connect/monitor IED -> select IED in persistent Explorer -> FAT`
+
+The first visible FAT frame must be the production FAT workspace for the selected Engineering IED. The primary flow must not require `Open SCL for FAT`, a launcher card, a second SCL parse, or a separate operator-visible FAT window.
+
+## Navigation invariant
+
+Engineering navigation has exactly seven destinations in this order:
+
+1. IEC 61850 Explorer
+2. Live Monitor
+3. Event Log
+4. Alarm
+5. GOOSE
+6. Diagnostics
+7. FAT
+
+There must be one navigation owner. Do not reintroduce a second `ModuleInitializer` / `ApplicationIdle` parity layer that fights the canonical navigation state.
+
+Target end-state: the FAT button and FAT `TabItem` are literal XAML siblings of the other six destinations and use the same `SegmentedNavButton` style resource.
+
+## Multi-IED context invariant
+
+When FAT is idle, the viewed FAT IED follows Engineering `SelectedDevice`.
+
+When a FAT session starts or continues, the capture target is latched to that session IED. Changing the Explorer selection may change the viewed IED but must never redirect an active capture/evidence transaction to another IED.
+
+Persisted FAT state is reconciled by stable device/IEC identity. Background reconciliation is read/reconcile-only and must not manufacture new evidence.
+
+## Static DataSet authority invariant
+
+Automatic Engineering FAT uses the authoritative static DataSet projection from the already parsed `SclIedWorkspace`.
+
+Synthesized `scl-manual-*` aliases must not be allowed to create duplicate enabled ownership of the same primary live leaf in automatic static mode. The strict duplicate-live-reference preflight guard remains enabled; invalid duplicate scope is cleaned up rather than weakening the guard.
+
+Manual-only projects keep their manual-row behavior.
+
+## FAT presentation invariant
+
+The final Engineering FAT center must reuse the exact production FAT grid presentation rather than an approximation or a second native FAT grid implementation.
+
+Target reusable structure:
+
+- `FatWorkspaceView`: canonical production grid/workflow presentation.
+- `FatReportPreviewView`: canonical production A4 preview presentation.
+- `IoListTestingWindow`: legacy standalone shell that may host the reusable views for compatibility, but must not be the presentation/lifecycle owner of the Engineering FAT tab.
+
+The Engineering FAT tab must eventually own a permanent FAT visual surface. Selecting FAT should only switch workstation content; it must not require `Window.Show -> Loaded -> detach/reparent`.
+
+## Report preview invariant
+
+Default center = production FAT grid.
+
+`Print/Report Preview` switches the same FAT center to the canonical paged A4 preview. The persistent IED Explorer and shared Command Dock remain visible. Returning from preview restores the same grid instance/state, including selection, scroll position, V1/V2 state, and active session context.
+
+## Protected production behavior
+
+Refactoring presentation must not change:
+
+- Select/SBO/Operate sequencing or control safety behavior.
+- `ctlModel`, interlock/synchrocheck/Test, CommandTermination semantics.
+- RCB runtime behavior.
+- GOOSE capture.
+- MMS/report/live-monitor acquisition semantics.
+- Production FAT preflight, auto-capture, evidence, completion/result, and persistence semantics.
+
+## Delivery gates
+
+A milestone is not called fixed until it has three statuses:
+
+- CODE VERIFIED
+- CI VERIFIED
+- FIELD VERIFIED
+
+Once a field gate is accepted, later milestones should not change that layer unless a regression test demonstrates a real dependency.
+
+## Current migration order
+
+1. M0 Architecture freeze and regression locks.
+2. M1 Canonical seven-destination shell/navigation.
+3. M2 Permanent FAT surface; remove primary launcher/black transition.
+4. M3 Selected-IED view synchronization.
+5. M4 Production controller adapter and latched capture context.
+6. M5 Evidence/persistence reconciliation.
+7. M6 Canonical in-place A4 report preview.
+8. M7 Remove donor-window/parity/experimental duplicate presentation code.
+9. M8 Physical-IED acceptance.

From 661f359c5412910f988202359b8139530f6239a6 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 06:54:56 +0700
Subject: [PATCH 04/84] FAT M1: add guarded canonical-shell migration

---
 tools/fat_m1_canonicalize.py | 96 ++++++++++++++++++++++++++++++++++++
 1 file changed, 96 insertions(+)
 create mode 100644 tools/fat_m1_canonicalize.py

diff --git a/tools/fat_m1_canonicalize.py b/tools/fat_m1_canonicalize.py
new file mode 100644
index 000000000..0d4516513
--- /dev/null
+++ b/tools/fat_m1_canonicalize.py
@@ -0,0 +1,96 @@
+from pathlib import Path
+
+
+def replace_once(path: Path, old: str, new: str, label: str) -> None:
+    text = path.read_text(encoding="utf-8")
+    count = text.count(old)
+    if count != 1:
+        raise SystemExit(f"{label}: expected exactly 1 match in {path}, found {count}")
+    path.write_text(text.replace(old, new, 1), encoding="utf-8")
+    print(f"patched {label}")
+
+
+xaml = Path("MainWindow.xaml")
+cs = Path("MainWindow.xaml.cs")
+native = Path("MainWindow.NativeFatWorkspace.cs")
+
+# --- MainWindow.xaml: one canonical seven-destination navigation shell. ---
+replace_once(
+    xaml,
+    '''                    <Grid.ColumnDefinitions>\n                        <ColumnDefinition Width="*"/>\n                        <ColumnDefinition Width="*"/>\n                        <ColumnDefinition Width="*"/>\n                        <ColumnDefinition Width="*"/>\n                        <ColumnDefinition Width="*"/>\n                        <ColumnDefinition Width="*"/>\n                    </Grid.ColumnDefinitions>\n                    <Border x:Name="WorkflowPill" Grid.ColumnSpan="6" Width="148" Height="34"''',
+    '''                    <Grid.ColumnDefinitions>\n                        <ColumnDefinition Width="*"/>\n                        <ColumnDefinition Width="*"/>\n                        <ColumnDefinition Width="*"/>\n                        <ColumnDefinition Width="*"/>\n                        <ColumnDefinition Width="*"/>\n                        <ColumnDefinition Width="*"/>\n                        <ColumnDefinition Width="*"/>\n                    </Grid.ColumnDefinitions>\n                    <Border x:Name="WorkflowPill" Grid.ColumnSpan="7" Width="112" Height="34"''',
+    "seven navigation columns and pill span",
+)
+
+replace_once(
+    xaml,
+    '''                    </Button>\n                </Grid>\n            </Border>\n\n            <!-- Runtime counts intentionally live only in the bottom status bar.''',
+    '''                    </Button>\n                    <Button x:Name="NavNativeFatButton" Grid.Column="6" Content="FAT" Tag="6" Click="NavButton_Click" Style="{StaticResource SegmentedNavButton}"/>\n                </Grid>\n            </Border>\n\n            <!-- Runtime counts intentionally live only in the bottom status bar.''',
+    "literal FAT navigation sibling",
+)
+
+replace_once(
+    xaml,
+    '''            </TabItem>\n                </TabControl>\n\n        <Border Grid.Row="2"''',
+    '''            </TabItem>\n\n            <!-- FAT: permanent seventh Engineering workspace host. Production presentation is mounted here. -->\n            <TabItem x:Name="NativeFatTab" Header="FAT">\n                <Grid/>\n            </TabItem>\n        </TabControl>\n\n        <Border Grid.Row="2"''',
+    "literal FAT tab sibling",
+)
+
+# --- MainWindow.xaml.cs: canonical navigation owns index 0..6 and geometry. ---
+replace_once(
+    cs,
+    '''    private void NavButton_Click(object sender, RoutedEventArgs e)\n    {\n        if (sender is not Button button || !int.TryParse(button.Tag?.ToString(), out var index))\n            return;\n        index = Math.Clamp(index, 0, 5);\n        MainTabs.SelectedIndex = index;\n        UpdateNavigationVisuals(index, animate: true);\n    }''',
+    '''    private void NavButton_Click(object sender, RoutedEventArgs e)\n    {\n        if (sender is not Button button || !int.TryParse(button.Tag?.ToString(), out var index))\n            return;\n        index = Math.Clamp(index, 0, NativeFatWorkspaceIndex);\n        MainTabs.SelectedIndex = index;\n        UpdateNavigationVisuals(index, animate: true);\n    }''',
+    "canonical seven-index nav click",
+)
+
+replace_once(
+    cs,
+    '''    private void UpdateNavigationVisuals(int index, bool animate)\n    {\n        if (WorkflowPillTranslate == null)\n            return;\n\n        var target = Math.Clamp(index, 0, 5) * 150d;\n        if (animate)\n        {\n            var animation = new DoubleAnimation(target, TimeSpan.FromMilliseconds(190))\n            {\n                EasingFunction = new CubicEase { EasingMode = EasingMode.EaseOut }\n            };\n            WorkflowPillTranslate.BeginAnimation(TranslateTransform.XProperty, animation);\n        }\n        else\n        {\n            WorkflowPillTranslate.BeginAnimation(TranslateTransform.XProperty, null);\n            WorkflowPillTranslate.X = target;\n        }\n\n        var buttons = new[] { NavExplorerButton, NavLiveButton, NavEventsButton, NavAlarmButton, NavGooseButton, NavDiagnosticsButton };\n        for (var i = 0; i < buttons.Length; i++)\n            buttons[i].Foreground = i == index ? Brushes.White : new SolidColorBrush(Color.FromRgb(71, 84, 103));\n    }''',
+    '''    private void UpdateNavigationVisuals(int index, bool animate)\n    {\n        if (WorkflowPillTranslate == null)\n            return;\n\n        index = Math.Clamp(index, 0, NativeFatWorkspaceIndex);\n\n        // MainWindow is the single owner of all seven Engineering destinations.\n        // Keep the same density used by the proven workstation shell while allowing\n        // enough width for the Explorer label and the new canonical FAT sibling.\n        var availableWidth = ActualWidth > 0d ? ActualWidth : 1480d;\n        var shellWidth = availableWidth >= 1700d ? 1085d : availableWidth >= 1380d ? 995d : 805d;\n        WorkflowNavShell.Width = shellWidth;\n        WorkflowNavShell.MinWidth = shellWidth;\n\n        var contentWidth = Math.Max(0d, shellWidth - WorkflowNavShell.Padding.Left - WorkflowNavShell.Padding.Right);\n        var cellWidth = contentWidth / 7d;\n        WorkflowPill.Width = Math.Max(1d, cellWidth - 2d);\n        var target = index * cellWidth;\n\n        if (animate)\n        {\n            var animation = new DoubleAnimation(target, TimeSpan.FromMilliseconds(190))\n            {\n                EasingFunction = new CubicEase { EasingMode = EasingMode.EaseOut }\n            };\n            WorkflowPillTranslate.BeginAnimation(TranslateTransform.XProperty, animation);\n        }\n        else\n        {\n            WorkflowPillTranslate.BeginAnimation(TranslateTransform.XProperty, null);\n            WorkflowPillTranslate.X = target;\n        }\n\n        var buttons = new[]\n        {\n            NavExplorerButton,\n            NavLiveButton,\n            NavEventsButton,\n            NavAlarmButton,\n            NavGooseButton,\n            NavDiagnosticsButton,\n            NavNativeFatButton\n        };\n        for (var i = 0; i < buttons.Length; i++)\n            buttons[i].Foreground = i == index ? Brushes.White : new SolidColorBrush(Color.FromRgb(71, 84, 103));\n    }''',
+    "canonical seven-slot visual owner",
+)
+
+# --- Native FAT bootstrap: consume the XAML-owned FAT tab/button; do not create shell UI. ---
+replace_once(
+    native,
+    '''        _nativeFatTab = new TabItem\n        {\n            Header = "FAT",\n            Content = BuildNativeFatWorkspaceContent()\n        };\n        MainTabs.Items.Add(_nativeFatTab);\n\n        // The command dock is deliberately shared, not cloned. FAT is command-centric,\n        // therefore start with the same expanded behavior as Explorer/Event Log.\n        _persistentWorkbench.DockExpandedByWorkspace[NativeFatWorkspaceIndex] = true;\n\n        InstallNativeFatNavigationButton();''',
+    '''        // M1: MainWindow.xaml owns the seventh tab and navigation button. The native\n        // FAT implementation temporarily supplies only content/state until the production\n        // reusable FAT surface replaces it in M2; it no longer creates workstation shell UI.\n        _nativeFatTab = NativeFatTab;\n        _nativeFatNavButton = NavNativeFatButton;\n        _nativeFatTab.Content = BuildNativeFatWorkspaceContent();\n\n        // The command dock is deliberately shared, not cloned. FAT is command-centric,\n        // therefore start with the same expanded behavior as Explorer/Event Log.\n        _persistentWorkbench.DockExpandedByWorkspace[NativeFatWorkspaceIndex] = true;''',
+    "bind Native FAT to canonical XAML shell",
+)
+
+start = native.read_text(encoding="utf-8")
+method_start = start.find("    private void InstallNativeFatNavigationButton()")
+method_end_marker = "    private void InstallNativeFatTimers()"
+method_end = start.find(method_end_marker, method_start)
+if method_start < 0 or method_end < 0:
+    raise SystemExit("dynamic FAT navigation method markers not found exactly once")
+start = start[:method_start] + start[method_end:]
+native.write_text(start, encoding="utf-8")
+print("removed dynamic FAT nav button creation")
+
+# Compatibility queue stays because production partials call it, but it delegates to the\n# canonical MainWindow navigation owner instead of maintaining a second geometry algorithm.
+text = native.read_text(encoding="utf-8")
+queue_start = text.find("    private void QueueNativeFatNavigationGeometry()")
+apply_marker = "    private void NativeFat_MainWindowPropertyChanged"
+queue_end = text.find(apply_marker, queue_start)
+if queue_start < 0 or queue_end < 0:
+    raise SystemExit("Native FAT navigation geometry block markers not found")
+replacement = '''    private void QueueNativeFatNavigationGeometry()\n    {\n        if (!_nativeFatInstalled)\n            return;\n\n        Dispatcher.BeginInvoke(\n            DispatcherPriority.ApplicationIdle,\n            new Action(() => UpdateNavigationVisuals(MainTabs.SelectedIndex, animate: false)));\n    }\n\n'''
+text = text[:queue_start] + replacement + text[queue_end:]
+native.write_text(text, encoding="utf-8")
+print("delegated Native FAT nav queue to canonical MainWindow owner")
+
+# Guard against accidental survival of the old shell creators.
+native_text = native.read_text(encoding="utf-8")
+for forbidden in ("MainTabs.Items.Add(_nativeFatTab)", "InstallNativeFatNavigationButton()", 'Name = "NavNativeFatButton"'):
+    if forbidden in native_text:
+        raise SystemExit(f"forbidden dynamic shell pattern survived: {forbidden}")
+
+xaml_text = xaml.read_text(encoding="utf-8")
+if xaml_text.count('x:Name="NavNativeFatButton"') != 1:
+    raise SystemExit("canonical FAT nav button count is not exactly one")
+if xaml_text.count('x:Name="NativeFatTab"') != 1:
+    raise SystemExit("canonical FAT TabItem count is not exactly one")
+
+print("FAT M1 canonical-shell migration complete")

From d56fdabc31cd12a22f5a3067071076845062bde8 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 06:55:06 +0700
Subject: [PATCH 05/84] FAT M1: run guarded canonical-shell migration

---
 .github/workflows/fat-m1-canonicalize.yml | 40 +++++++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100644 .github/workflows/fat-m1-canonicalize.yml

diff --git a/.github/workflows/fat-m1-canonicalize.yml b/.github/workflows/fat-m1-canonicalize.yml
new file mode 100644
index 000000000..0c57c2bfc
--- /dev/null
+++ b/.github/workflows/fat-m1-canonicalize.yml
@@ -0,0 +1,40 @@
+name: FAT M1 canonical shell migration
+
+on:
+  push:
+    branches:
+      - fix/fat-workstation-convergence
+    paths:
+      - tools/fat_m1_canonicalize.py
+      - .github/workflows/fat-m1-canonicalize.yml
+
+permissions:
+  contents: write
+
+jobs:
+  canonicalize:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout staging branch
+        uses: actions/checkout@v4
+        with:
+          ref: fix/fat-workstation-convergence
+          fetch-depth: 0
+
+      - name: Apply guarded M1 migration
+        run: python tools/fat_m1_canonicalize.py
+
+      - name: Remove one-shot migration helpers
+        run: |
+          rm tools/fat_m1_canonicalize.py
+          rm .github/workflows/fat-m1-canonicalize.yml
+
+      - name: Commit canonical shell
+        shell: bash
+        run: |
+          git config user.name "github-actions[bot]"
+          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
+          git add MainWindow.xaml MainWindow.xaml.cs MainWindow.NativeFatWorkspace.cs tools/fat_m1_canonicalize.py .github/workflows/fat-m1-canonicalize.yml
+          git diff --cached --check
+          git commit -m "FAT M1: make seven-destination shell canonical"
+          git push origin HEAD:fix/fat-workstation-convergence

From 4fd3d6f5a37b140bf1f852b0d939179ad0fd8e0e Mon Sep 17 00:00:00 2001
From: "github-actions[bot]"
 <41898282+github-actions[bot]@users.noreply.github.com>
Date: Wed, 9 Sep 2026 23:55:13 +0000
Subject: [PATCH 06/84] FAT M1: make seven-destination shell canonical

---
 .github/workflows/fat-m1-canonicalize.yml | 40 ----------
 MainWindow.NativeFatWorkspace.cs          | 96 ++---------------------
 MainWindow.xaml                           | 11 ++-
 MainWindow.xaml.cs                        | 29 ++++++-
 tools/fat_m1_canonicalize.py              | 96 -----------------------
 5 files changed, 43 insertions(+), 229 deletions(-)
 delete mode 100644 .github/workflows/fat-m1-canonicalize.yml
 delete mode 100644 tools/fat_m1_canonicalize.py

diff --git a/.github/workflows/fat-m1-canonicalize.yml b/.github/workflows/fat-m1-canonicalize.yml
deleted file mode 100644
index 0c57c2bfc..000000000
--- a/.github/workflows/fat-m1-canonicalize.yml
+++ /dev/null
@@ -1,40 +0,0 @@
-name: FAT M1 canonical shell migration
-
-on:
-  push:
-    branches:
-      - fix/fat-workstation-convergence
-    paths:
-      - tools/fat_m1_canonicalize.py
-      - .github/workflows/fat-m1-canonicalize.yml
-
-permissions:
-  contents: write
-
-jobs:
-  canonicalize:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout staging branch
-        uses: actions/checkout@v4
-        with:
-          ref: fix/fat-workstation-convergence
-          fetch-depth: 0
-
-      - name: Apply guarded M1 migration
-        run: python tools/fat_m1_canonicalize.py
-
-      - name: Remove one-shot migration helpers
-        run: |
-          rm tools/fat_m1_canonicalize.py
-          rm .github/workflows/fat-m1-canonicalize.yml
-
-      - name: Commit canonical shell
-        shell: bash
-        run: |
-          git config user.name "github-actions[bot]"
-          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
-          git add MainWindow.xaml MainWindow.xaml.cs MainWindow.NativeFatWorkspace.cs tools/fat_m1_canonicalize.py .github/workflows/fat-m1-canonicalize.yml
-          git diff --cached --check
-          git commit -m "FAT M1: make seven-destination shell canonical"
-          git push origin HEAD:fix/fat-workstation-convergence
diff --git a/MainWindow.NativeFatWorkspace.cs b/MainWindow.NativeFatWorkspace.cs
index 3c28770ea..422219781 100644
--- a/MainWindow.NativeFatWorkspace.cs
+++ b/MainWindow.NativeFatWorkspace.cs
@@ -102,18 +102,16 @@ private void TryInstallNativeFatWorkspace()
         _nativeFatInstallRetry?.Stop();
         _nativeFatInstalled = true;
 
-        _nativeFatTab = new TabItem
-        {
-            Header = "FAT",
-            Content = BuildNativeFatWorkspaceContent()
-        };
-        MainTabs.Items.Add(_nativeFatTab);
+        // M1: MainWindow.xaml owns the seventh tab and navigation button. The native
+        // FAT implementation temporarily supplies only content/state until the production
+        // reusable FAT surface replaces it in M2; it no longer creates workstation shell UI.
+        _nativeFatTab = NativeFatTab;
+        _nativeFatNavButton = NavNativeFatButton;
+        _nativeFatTab.Content = BuildNativeFatWorkspaceContent();
 
         // The command dock is deliberately shared, not cloned. FAT is command-centric,
         // therefore start with the same expanded behavior as Explorer/Event Log.
         _persistentWorkbench.DockExpandedByWorkspace[NativeFatWorkspaceIndex] = true;
-
-        InstallNativeFatNavigationButton();
         InstallNativeFatTimers();
         AttachNativeFatObservedDevice(SelectedDevice);
 
@@ -450,30 +448,6 @@ private Button CreateNativeFatButton(string text, RoutedEventHandler click, stri
         return button;
     }
 
-    private void InstallNativeFatNavigationButton()
-    {
-        if (_nativeFatNavButton != null)
-            return;
-
-        while (WorkflowNavGrid.ColumnDefinitions.Count < 7)
-            WorkflowNavGrid.ColumnDefinitions.Add(new ColumnDefinition { Width = new GridLength(1, GridUnitType.Star) });
-
-        Grid.SetColumnSpan(WorkflowPill, 7);
-        _nativeFatNavButton = new Button
-        {
-            Name = "NavNativeFatButton",
-            Content = "FAT",
-            Tag = NativeFatWorkspaceIndex,
-            MinWidth = 0,
-            ToolTip = "Continuous FAT testing using the selected IED and live Explorer signal authority"
-        };
-        if (TryFindResource("SegmentedNavButton") is Style navStyle)
-            _nativeFatNavButton.Style = navStyle;
-        _nativeFatNavButton.Click += NativeFatNavButton_Click;
-        Grid.SetColumn(_nativeFatNavButton, 6);
-        WorkflowNavGrid.Children.Add(_nativeFatNavButton);
-    }
-
     private void InstallNativeFatTimers()
     {
         _nativeFatReconcileTimer = new DispatcherTimer(DispatcherPriority.Background)
@@ -518,64 +492,10 @@ private void QueueNativeFatNavigationGeometry()
     {
         if (!_nativeFatInstalled)
             return;
+
         Dispatcher.BeginInvoke(
             DispatcherPriority.ApplicationIdle,
-            new Action(ApplyNativeFatNavigationGeometry));
-    }
-
-    private void ApplyNativeFatNavigationGeometry()
-    {
-        if (!_nativeFatInstalled || _nativeFatNavButton == null)
-            return;
-
-        var availableWidth = ActualWidth > 0d ? ActualWidth : 1480d;
-        var wide = availableWidth >= 1700d;
-        var medium = availableWidth >= 1380d;
-        var shellWidth = wide ? 1085d : medium ? 995d : 805d;
-
-        WorkflowNavShell.Width = shellWidth;
-        WorkflowNavShell.MinWidth = shellWidth;
-        WorkflowNavShell.Height = 60;
-        WorkflowNavShell.Padding = new Thickness(5, 6, 5, 6);
-        WorkflowNavGrid.ClipToBounds = false;
-
-        while (WorkflowNavGrid.ColumnDefinitions.Count < 7)
-            WorkflowNavGrid.ColumnDefinitions.Add(new ColumnDefinition { Width = new GridLength(1, GridUnitType.Star) });
-        foreach (var column in WorkflowNavGrid.ColumnDefinitions)
-            column.Width = new GridLength(1, GridUnitType.Star);
-
-        var buttons = new[]
-        {
-            NavExplorerButton,
-            NavLiveButton,
-            NavEventsButton,
-            NavAlarmButton,
-            NavGooseButton,
-            NavDiagnosticsButton,
-            _nativeFatNavButton
-        };
-        for (var index = 0; index < buttons.Length; index++)
-        {
-            var button = buttons[index];
-            button.MinHeight = 40;
-            button.MinWidth = 0;
-            button.Margin = new Thickness(1);
-            button.Padding = wide ? new Thickness(9, 7, 9, 7) : new Thickness(5, 7, 5, 7);
-            button.HorizontalContentAlignment = HorizontalAlignment.Center;
-            button.VerticalContentAlignment = VerticalAlignment.Center;
-            button.Foreground = index == MainTabs.SelectedIndex
-                ? Brushes.White
-                : ResourceBrush("Muted", Color.FromRgb(0x5F, 0x6B, 0x7A));
-        }
-
-        Grid.SetColumnSpan(WorkflowPill, 7);
-        var contentWidth = Math.Max(0d, shellWidth - WorkflowNavShell.Padding.Left - WorkflowNavShell.Padding.Right);
-        var cellWidth = contentWidth / 7d;
-        WorkflowPill.Width = Math.Max(1d, cellWidth - 2d);
-        WorkflowPill.Height = 36;
-
-        WorkflowPillTranslate.BeginAnimation(TranslateTransform.XProperty, null);
-        WorkflowPillTranslate.X = Math.Clamp(MainTabs.SelectedIndex, 0, NativeFatWorkspaceIndex) * cellWidth;
+            new Action(() => UpdateNavigationVisuals(MainTabs.SelectedIndex, animate: false)));
     }
 
     private void NativeFat_MainWindowPropertyChanged(object? sender, PropertyChangedEventArgs e)
diff --git a/MainWindow.xaml b/MainWindow.xaml
index 205519e97..af057d89c 100644
--- a/MainWindow.xaml
+++ b/MainWindow.xaml
@@ -121,8 +121,9 @@
                         <ColumnDefinition Width="*"/>
                         <ColumnDefinition Width="*"/>
                         <ColumnDefinition Width="*"/>
+                        <ColumnDefinition Width="*"/>
                     </Grid.ColumnDefinitions>
-                    <Border x:Name="WorkflowPill" Grid.ColumnSpan="6" Width="148" Height="34"
+                    <Border x:Name="WorkflowPill" Grid.ColumnSpan="7" Width="112" Height="34"
                             HorizontalAlignment="Left" VerticalAlignment="Center" CornerRadius="17"
                             Background="{StaticResource Accent}" RenderTransformOrigin="0.5,0.5">
                         <Border.RenderTransform>
@@ -151,6 +152,7 @@
                             </Border>
                         </StackPanel>
                     </Button>
+                    <Button x:Name="NavNativeFatButton" Grid.Column="6" Content="FAT" Tag="6" Click="NavButton_Click" Style="{StaticResource SegmentedNavButton}"/>
                 </Grid>
             </Border>
 
@@ -1684,7 +1686,12 @@
                     </DockPanel>
                 </Border>
             </TabItem>
-                </TabControl>
+
+            <!-- FAT: permanent seventh Engineering workspace host. Production presentation is mounted here. -->
+            <TabItem x:Name="NativeFatTab" Header="FAT">
+                <Grid/>
+            </TabItem>
+        </TabControl>
 
         <Border Grid.Row="2" Margin="0,10,0,0" Background="#EAF1FF" BorderBrush="#CFE0FF" BorderThickness="1" CornerRadius="14" Padding="11,7">
             <Grid>
diff --git a/MainWindow.xaml.cs b/MainWindow.xaml.cs
index 4f55a7528..00ae66f8a 100644
--- a/MainWindow.xaml.cs
+++ b/MainWindow.xaml.cs
@@ -620,7 +620,7 @@ private void NavButton_Click(object sender, RoutedEventArgs e)
     {
         if (sender is not Button button || !int.TryParse(button.Tag?.ToString(), out var index))
             return;
-        index = Math.Clamp(index, 0, 5);
+        index = Math.Clamp(index, 0, NativeFatWorkspaceIndex);
         MainTabs.SelectedIndex = index;
         UpdateNavigationVisuals(index, animate: true);
     }
@@ -654,7 +654,21 @@ private void UpdateNavigationVisuals(int index, bool animate)
         if (WorkflowPillTranslate == null)
             return;
 
-        var target = Math.Clamp(index, 0, 5) * 150d;
+        index = Math.Clamp(index, 0, NativeFatWorkspaceIndex);
+
+        // MainWindow is the single owner of all seven Engineering destinations.
+        // Keep the same density used by the proven workstation shell while allowing
+        // enough width for the Explorer label and the new canonical FAT sibling.
+        var availableWidth = ActualWidth > 0d ? ActualWidth : 1480d;
+        var shellWidth = availableWidth >= 1700d ? 1085d : availableWidth >= 1380d ? 995d : 805d;
+        WorkflowNavShell.Width = shellWidth;
+        WorkflowNavShell.MinWidth = shellWidth;
+
+        var contentWidth = Math.Max(0d, shellWidth - WorkflowNavShell.Padding.Left - WorkflowNavShell.Padding.Right);
+        var cellWidth = contentWidth / 7d;
+        WorkflowPill.Width = Math.Max(1d, cellWidth - 2d);
+        var target = index * cellWidth;
+
         if (animate)
         {
             var animation = new DoubleAnimation(target, TimeSpan.FromMilliseconds(190))
@@ -669,7 +683,16 @@ private void UpdateNavigationVisuals(int index, bool animate)
             WorkflowPillTranslate.X = target;
         }
 
-        var buttons = new[] { NavExplorerButton, NavLiveButton, NavEventsButton, NavAlarmButton, NavGooseButton, NavDiagnosticsButton };
+        var buttons = new[]
+        {
+            NavExplorerButton,
+            NavLiveButton,
+            NavEventsButton,
+            NavAlarmButton,
+            NavGooseButton,
+            NavDiagnosticsButton,
+            NavNativeFatButton
+        };
         for (var i = 0; i < buttons.Length; i++)
             buttons[i].Foreground = i == index ? Brushes.White : new SolidColorBrush(Color.FromRgb(71, 84, 103));
     }
diff --git a/tools/fat_m1_canonicalize.py b/tools/fat_m1_canonicalize.py
deleted file mode 100644
index 0d4516513..000000000
--- a/tools/fat_m1_canonicalize.py
+++ /dev/null
@@ -1,96 +0,0 @@
-from pathlib import Path
-
-
-def replace_once(path: Path, old: str, new: str, label: str) -> None:
-    text = path.read_text(encoding="utf-8")
-    count = text.count(old)
-    if count != 1:
-        raise SystemExit(f"{label}: expected exactly 1 match in {path}, found {count}")
-    path.write_text(text.replace(old, new, 1), encoding="utf-8")
-    print(f"patched {label}")
-
-
-xaml = Path("MainWindow.xaml")
-cs = Path("MainWindow.xaml.cs")
-native = Path("MainWindow.NativeFatWorkspace.cs")
-
-# --- MainWindow.xaml: one canonical seven-destination navigation shell. ---
-replace_once(
-    xaml,
-    '''                    <Grid.ColumnDefinitions>\n                        <ColumnDefinition Width="*"/>\n                        <ColumnDefinition Width="*"/>\n                        <ColumnDefinition Width="*"/>\n                        <ColumnDefinition Width="*"/>\n                        <ColumnDefinition Width="*"/>\n                        <ColumnDefinition Width="*"/>\n                    </Grid.ColumnDefinitions>\n                    <Border x:Name="WorkflowPill" Grid.ColumnSpan="6" Width="148" Height="34"''',
-    '''                    <Grid.ColumnDefinitions>\n                        <ColumnDefinition Width="*"/>\n                        <ColumnDefinition Width="*"/>\n                        <ColumnDefinition Width="*"/>\n                        <ColumnDefinition Width="*"/>\n                        <ColumnDefinition Width="*"/>\n                        <ColumnDefinition Width="*"/>\n                        <ColumnDefinition Width="*"/>\n                    </Grid.ColumnDefinitions>\n                    <Border x:Name="WorkflowPill" Grid.ColumnSpan="7" Width="112" Height="34"''',
-    "seven navigation columns and pill span",
-)
-
-replace_once(
-    xaml,
-    '''                    </Button>\n                </Grid>\n            </Border>\n\n            <!-- Runtime counts intentionally live only in the bottom status bar.''',
-    '''                    </Button>\n                    <Button x:Name="NavNativeFatButton" Grid.Column="6" Content="FAT" Tag="6" Click="NavButton_Click" Style="{StaticResource SegmentedNavButton}"/>\n                </Grid>\n            </Border>\n\n            <!-- Runtime counts intentionally live only in the bottom status bar.''',
-    "literal FAT navigation sibling",
-)
-
-replace_once(
-    xaml,
-    '''            </TabItem>\n                </TabControl>\n\n        <Border Grid.Row="2"''',
-    '''            </TabItem>\n\n            <!-- FAT: permanent seventh Engineering workspace host. Production presentation is mounted here. -->\n            <TabItem x:Name="NativeFatTab" Header="FAT">\n                <Grid/>\n            </TabItem>\n        </TabControl>\n\n        <Border Grid.Row="2"''',
-    "literal FAT tab sibling",
-)
-
-# --- MainWindow.xaml.cs: canonical navigation owns index 0..6 and geometry. ---
-replace_once(
-    cs,
-    '''    private void NavButton_Click(object sender, RoutedEventArgs e)\n    {\n        if (sender is not Button button || !int.TryParse(button.Tag?.ToString(), out var index))\n            return;\n        index = Math.Clamp(index, 0, 5);\n        MainTabs.SelectedIndex = index;\n        UpdateNavigationVisuals(index, animate: true);\n    }''',
-    '''    private void NavButton_Click(object sender, RoutedEventArgs e)\n    {\n        if (sender is not Button button || !int.TryParse(button.Tag?.ToString(), out var index))\n            return;\n        index = Math.Clamp(index, 0, NativeFatWorkspaceIndex);\n        MainTabs.SelectedIndex = index;\n        UpdateNavigationVisuals(index, animate: true);\n    }''',
-    "canonical seven-index nav click",
-)
-
-replace_once(
-    cs,
-    '''    private void UpdateNavigationVisuals(int index, bool animate)\n    {\n        if (WorkflowPillTranslate == null)\n            return;\n\n        var target = Math.Clamp(index, 0, 5) * 150d;\n        if (animate)\n        {\n            var animation = new DoubleAnimation(target, TimeSpan.FromMilliseconds(190))\n            {\n                EasingFunction = new CubicEase { EasingMode = EasingMode.EaseOut }\n            };\n            WorkflowPillTranslate.BeginAnimation(TranslateTransform.XProperty, animation);\n        }\n        else\n        {\n            WorkflowPillTranslate.BeginAnimation(TranslateTransform.XProperty, null);\n            WorkflowPillTranslate.X = target;\n        }\n\n        var buttons = new[] { NavExplorerButton, NavLiveButton, NavEventsButton, NavAlarmButton, NavGooseButton, NavDiagnosticsButton };\n        for (var i = 0; i < buttons.Length; i++)\n            buttons[i].Foreground = i == index ? Brushes.White : new SolidColorBrush(Color.FromRgb(71, 84, 103));\n    }''',
-    '''    private void UpdateNavigationVisuals(int index, bool animate)\n    {\n        if (WorkflowPillTranslate == null)\n            return;\n\n        index = Math.Clamp(index, 0, NativeFatWorkspaceIndex);\n\n        // MainWindow is the single owner of all seven Engineering destinations.\n        // Keep the same density used by the proven workstation shell while allowing\n        // enough width for the Explorer label and the new canonical FAT sibling.\n        var availableWidth = ActualWidth > 0d ? ActualWidth : 1480d;\n        var shellWidth = availableWidth >= 1700d ? 1085d : availableWidth >= 1380d ? 995d : 805d;\n        WorkflowNavShell.Width = shellWidth;\n        WorkflowNavShell.MinWidth = shellWidth;\n\n        var contentWidth = Math.Max(0d, shellWidth - WorkflowNavShell.Padding.Left - WorkflowNavShell.Padding.Right);\n        var cellWidth = contentWidth / 7d;\n        WorkflowPill.Width = Math.Max(1d, cellWidth - 2d);\n        var target = index * cellWidth;\n\n        if (animate)\n        {\n            var animation = new DoubleAnimation(target, TimeSpan.FromMilliseconds(190))\n            {\n                EasingFunction = new CubicEase { EasingMode = EasingMode.EaseOut }\n            };\n            WorkflowPillTranslate.BeginAnimation(TranslateTransform.XProperty, animation);\n        }\n        else\n        {\n            WorkflowPillTranslate.BeginAnimation(TranslateTransform.XProperty, null);\n            WorkflowPillTranslate.X = target;\n        }\n\n        var buttons = new[]\n        {\n            NavExplorerButton,\n            NavLiveButton,\n            NavEventsButton,\n            NavAlarmButton,\n            NavGooseButton,\n            NavDiagnosticsButton,\n            NavNativeFatButton\n        };\n        for (var i = 0; i < buttons.Length; i++)\n            buttons[i].Foreground = i == index ? Brushes.White : new SolidColorBrush(Color.FromRgb(71, 84, 103));\n    }''',
-    "canonical seven-slot visual owner",
-)
-
-# --- Native FAT bootstrap: consume the XAML-owned FAT tab/button; do not create shell UI. ---
-replace_once(
-    native,
-    '''        _nativeFatTab = new TabItem\n        {\n            Header = "FAT",\n            Content = BuildNativeFatWorkspaceContent()\n        };\n        MainTabs.Items.Add(_nativeFatTab);\n\n        // The command dock is deliberately shared, not cloned. FAT is command-centric,\n        // therefore start with the same expanded behavior as Explorer/Event Log.\n        _persistentWorkbench.DockExpandedByWorkspace[NativeFatWorkspaceIndex] = true;\n\n        InstallNativeFatNavigationButton();''',
-    '''        // M1: MainWindow.xaml owns the seventh tab and navigation button. The native\n        // FAT implementation temporarily supplies only content/state until the production\n        // reusable FAT surface replaces it in M2; it no longer creates workstation shell UI.\n        _nativeFatTab = NativeFatTab;\n        _nativeFatNavButton = NavNativeFatButton;\n        _nativeFatTab.Content = BuildNativeFatWorkspaceContent();\n\n        // The command dock is deliberately shared, not cloned. FAT is command-centric,\n        // therefore start with the same expanded behavior as Explorer/Event Log.\n        _persistentWorkbench.DockExpandedByWorkspace[NativeFatWorkspaceIndex] = true;''',
-    "bind Native FAT to canonical XAML shell",
-)
-
-start = native.read_text(encoding="utf-8")
-method_start = start.find("    private void InstallNativeFatNavigationButton()")
-method_end_marker = "    private void InstallNativeFatTimers()"
-method_end = start.find(method_end_marker, method_start)
-if method_start < 0 or method_end < 0:
-    raise SystemExit("dynamic FAT navigation method markers not found exactly once")
-start = start[:method_start] + start[method_end:]
-native.write_text(start, encoding="utf-8")
-print("removed dynamic FAT nav button creation")
-
-# Compatibility queue stays because production partials call it, but it delegates to the\n# canonical MainWindow navigation owner instead of maintaining a second geometry algorithm.
-text = native.read_text(encoding="utf-8")
-queue_start = text.find("    private void QueueNativeFatNavigationGeometry()")
-apply_marker = "    private void NativeFat_MainWindowPropertyChanged"
-queue_end = text.find(apply_marker, queue_start)
-if queue_start < 0 or queue_end < 0:
-    raise SystemExit("Native FAT navigation geometry block markers not found")
-replacement = '''    private void QueueNativeFatNavigationGeometry()\n    {\n        if (!_nativeFatInstalled)\n            return;\n\n        Dispatcher.BeginInvoke(\n            DispatcherPriority.ApplicationIdle,\n            new Action(() => UpdateNavigationVisuals(MainTabs.SelectedIndex, animate: false)));\n    }\n\n'''
-text = text[:queue_start] + replacement + text[queue_end:]
-native.write_text(text, encoding="utf-8")
-print("delegated Native FAT nav queue to canonical MainWindow owner")
-
-# Guard against accidental survival of the old shell creators.
-native_text = native.read_text(encoding="utf-8")
-for forbidden in ("MainTabs.Items.Add(_nativeFatTab)", "InstallNativeFatNavigationButton()", 'Name = "NavNativeFatButton"'):
-    if forbidden in native_text:
-        raise SystemExit(f"forbidden dynamic shell pattern survived: {forbidden}")
-
-xaml_text = xaml.read_text(encoding="utf-8")
-if xaml_text.count('x:Name="NavNativeFatButton"') != 1:
-    raise SystemExit("canonical FAT nav button count is not exactly one")
-if xaml_text.count('x:Name="NativeFatTab"') != 1:
-    raise SystemExit("canonical FAT TabItem count is not exactly one")
-
-print("FAT M1 canonical-shell migration complete")

From 7085d3f0be4dc4e9bb31bdf02ed85eaff2e71fe6 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 06:56:20 +0700
Subject: [PATCH 07/84] FAT M1: keep navigation ownership in canonical
 MainWindow

---
 MainWindow.ProductionFatTab.cs | 26 +++++---------------------
 1 file changed, 5 insertions(+), 21 deletions(-)

diff --git a/MainWindow.ProductionFatTab.cs b/MainWindow.ProductionFatTab.cs
index b0d01d9e3..33a9f3c46 100644
--- a/MainWindow.ProductionFatTab.cs
+++ b/MainWindow.ProductionFatTab.cs
@@ -46,8 +46,9 @@ private void TryInstallProductionFatTabPivot()
         if (_productionFatTabInstalled || !IsLoaded)
             return;
 
-        // PR #290 creates the seventh navigation slot. Wait until that shell contribution
-        // exists, then replace only its FAT content/handlers; P0/P1 shell geometry is untouched.
+        // The seventh FAT destination is now canonical MainWindow XAML. Wait only for the
+        // native FAT state contribution to bind its compatibility fields; do not create,
+        // restyle, or re-own navigation here.
         if (!_nativeFatInstalled || _nativeFatTab == null || _nativeFatNavButton == null)
         {
             _productionFatInstallRetry ??= new DispatcherTimer(DispatcherPriority.ApplicationIdle)
@@ -70,18 +71,12 @@ private void TryInstallProductionFatTabPivot()
         AttachNativeFatObservedDevice(null);
         PropertyChanged -= NativeFat_MainWindowPropertyChanged;
         MainTabs.SelectionChanged -= NativeFat_MainTabsSelectionChanged;
-        _nativeFatNavButton.Click -= NativeFatNavButton_Click;
 
         _nativeFatTab.Content = BuildProductionFatLauncher();
 
-        // FAT must be visually indistinguishable from the existing workflow tabs.
-        _nativeFatNavButton.Style = NavDiagnosticsButton.Style;
-        _nativeFatNavButton.Padding = NavDiagnosticsButton.Padding;
-        _nativeFatNavButton.Margin = NavDiagnosticsButton.Margin;
-        _nativeFatNavButton.HorizontalContentAlignment = NavDiagnosticsButton.HorizontalContentAlignment;
-        _nativeFatNavButton.VerticalContentAlignment = NavDiagnosticsButton.VerticalContentAlignment;
+        // MainWindow.xaml owns the FAT button's SegmentedNavButton style and NavButton_Click.
+        // Production FAT reacts to tab selection below; it must not install a second click owner.
         _nativeFatNavButton.ToolTip = "Production FAT workspace · automatic Value 1 / Value 2 evidence capture";
-        _nativeFatNavButton.Click += ProductionFatNavButton_Click;
 
         PropertyChanged += ProductionFat_MainWindowPropertyChanged;
         MainTabs.SelectionChanged += ProductionFat_MainTabsSelectionChanged;
@@ -178,17 +173,6 @@ private FrameworkElement BuildProductionFatLauncher()
         return root;
     }
 
-    private void ProductionFatNavButton_Click(object sender, RoutedEventArgs e)
-    {
-        if (MainTabs.Items.Count <= NativeFatWorkspaceIndex)
-            return;
-
-        MainTabs.SelectedIndex = NativeFatWorkspaceIndex;
-        QueueNativeFatNavigationGeometry();
-        SynchronizeProductionFatSelectedIed();
-        _productionFatWindow?.NotifyEmbeddedHostActivated();
-    }
-
     private void ProductionFat_MainTabsSelectionChanged(object sender, SelectionChangedEventArgs e)
     {
         if (!ReferenceEquals(e.Source, MainTabs))

From 1710c52952737bb08e35c716447ff9fad2119747 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 06:56:44 +0700
Subject: [PATCH 08/84] FAT M1: lock canonical seven-destination shell
 ownership

---
 ...ductionFatEngineeringTabRegressionTests.cs | 41 ++++++++++++++++---
 1 file changed, 35 insertions(+), 6 deletions(-)

diff --git a/tests/ARSAS.Tests/ProductionFatEngineeringTabRegressionTests.cs b/tests/ARSAS.Tests/ProductionFatEngineeringTabRegressionTests.cs
index 2f6f94ec2..9da4dd527 100644
--- a/tests/ARSAS.Tests/ProductionFatEngineeringTabRegressionTests.cs
+++ b/tests/ARSAS.Tests/ProductionFatEngineeringTabRegressionTests.cs
@@ -44,18 +44,47 @@ public void ProductionFatTab_RegistersExactEngineeringRuntimeWorkspacesForShared
     }
 
     [Fact]
-    public void SeventhFatDestination_HasOnlyOneSevenSlotCompatibilityOwner()
+    public void SeventhFatDestination_IsCanonicalMainWindowSiblingWithOneNavigationOwner()
     {
+        var xaml = File.ReadAllText(FindRepoFile("MainWindow.xaml"));
+        var mainSource = File.ReadAllText(FindRepoFile("MainWindow.xaml.cs"));
         var nativeSource = File.ReadAllText(FindRepoFile("MainWindow.NativeFatWorkspace.cs"));
+        var productionSource = File.ReadAllText(FindRepoFile("MainWindow.ProductionFatTab.cs"));
         var repoRoot = FindRepoRoot();
 
-        Assert.Contains("NavNativeFatButton", nativeSource, StringComparison.Ordinal);
-        Assert.Contains("TryFindResource(\"SegmentedNavButton\")", nativeSource, StringComparison.Ordinal);
-        Assert.Contains("var cellWidth = contentWidth / 7d", nativeSource, StringComparison.Ordinal);
-        Assert.Contains("Math.Clamp(MainTabs.SelectedIndex, 0, NativeFatWorkspaceIndex)", nativeSource, StringComparison.Ordinal);
+        Assert.Contains("x:Name=\"NavNativeFatButton\" Grid.Column=\"6\" Content=\"FAT\" Tag=\"6\" Click=\"NavButton_Click\" Style=\"{StaticResource SegmentedNavButton}\"", xaml, StringComparison.Ordinal);
+        Assert.Contains("Grid.ColumnSpan=\"7\"", xaml, StringComparison.Ordinal);
+        Assert.Contains("x:Name=\"NativeFatTab\" Header=\"FAT\"", xaml, StringComparison.Ordinal);
+
+        Assert.Contains("Math.Clamp(index, 0, NativeFatWorkspaceIndex)", mainSource, StringComparison.Ordinal);
+        Assert.Contains("var cellWidth = contentWidth / 7d", mainSource, StringComparison.Ordinal);
+        Assert.Contains("NavNativeFatButton", mainSource, StringComparison.Ordinal);
+
+        Assert.Contains("_nativeFatTab = NativeFatTab", nativeSource, StringComparison.Ordinal);
+        Assert.Contains("_nativeFatNavButton = NavNativeFatButton", nativeSource, StringComparison.Ordinal);
+        Assert.DoesNotContain("MainTabs.Items.Add(_nativeFatTab)", nativeSource, StringComparison.Ordinal);
+        Assert.DoesNotContain("InstallNativeFatNavigationButton", nativeSource, StringComparison.Ordinal);
+        Assert.DoesNotContain("Name = \"NavNativeFatButton\"", nativeSource, StringComparison.Ordinal);
+        Assert.DoesNotContain("var cellWidth = contentWidth / 7d", nativeSource, StringComparison.Ordinal);
+
+        Assert.DoesNotContain("ProductionFatNavButton_Click", productionSource, StringComparison.Ordinal);
+        Assert.DoesNotContain("_nativeFatNavButton.Style =", productionSource, StringComparison.Ordinal);
+        Assert.DoesNotContain("_nativeFatNavButton.Click +=", productionSource, StringComparison.Ordinal);
+
         Assert.False(
             File.Exists(Path.Combine(repoRoot, "MainWindow.ProductionFatNavigationParity.cs")),
-            "Do not reintroduce a second ApplicationIdle navigation parity owner. Seven-slot navigation must converge toward one canonical owner.");
+            "Do not reintroduce a second ApplicationIdle navigation parity owner. MainWindow is the seven-slot navigation authority.");
+    }
+
+    [Fact]
+    public void ExistingWorkspaceSelectionSideEffects_RemainProtectedWhileAddingFat()
+    {
+        var source = File.ReadAllText(FindRepoFile("MainWindow.xaml.cs"));
+
+        Assert.Contains("device.ClearUnreadEvents()", source, StringComparison.Ordinal);
+        Assert.Contains("ActivateGooseSubscriberWorkspace()", source, StringComparison.Ordinal);
+        Assert.Contains("ClearDiagnosticAlert()", source, StringComparison.Ordinal);
+        Assert.Contains("UpdateNavigationVisuals(MainTabs.SelectedIndex, animate: true)", source, StringComparison.Ordinal);
     }
 
     [Fact]

From f5d0458de643e9fe7c85824a5b5f097ffd4b3467 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 08:04:04 +0700
Subject: [PATCH 09/84] ci: guarded M1 seven-slot consistency fix

---
 .../fat-m1-seven-slot-guarded-fix.yml         | 73 +++++++++++++++++++
 1 file changed, 73 insertions(+)
 create mode 100644 .github/workflows/fat-m1-seven-slot-guarded-fix.yml

diff --git a/.github/workflows/fat-m1-seven-slot-guarded-fix.yml b/.github/workflows/fat-m1-seven-slot-guarded-fix.yml
new file mode 100644
index 000000000..8ab15ac00
--- /dev/null
+++ b/.github/workflows/fat-m1-seven-slot-guarded-fix.yml
@@ -0,0 +1,73 @@
+name: FAT M1 seven-slot guarded consistency fix
+
+on:
+  push:
+    branches:
+      - fix/fat-workstation-convergence
+    paths:
+      - .github/workflows/fat-m1-seven-slot-guarded-fix.yml
+
+permissions:
+  contents: write
+
+jobs:
+  migrate:
+    runs-on: windows-latest
+    steps:
+      - name: Checkout staging branch
+        uses: actions/checkout@v4
+        with:
+          ref: fix/fat-workstation-convergence
+          fetch-depth: 0
+
+      - name: Apply guarded seven-slot consistency migration
+        shell: pwsh
+        run: |
+          $ErrorActionPreference = 'Stop'
+
+          function Replace-Exact([string]$Path, [string]$Old, [string]$New, [int]$ExpectedCount = 1) {
+            $text = Get-Content $Path -Raw
+            $count = ([regex]::Matches($text, [regex]::Escape($Old))).Count
+            if ($count -ne $ExpectedCount) {
+              throw "Guard failed for $Path. Expected $ExpectedCount occurrence(s) of [$Old], found $count."
+            }
+            $text = $text.Replace($Old, $New)
+            Set-Content -Path $Path -Value $text -NoNewline -Encoding utf8
+          }
+
+          $nav = 'MainWindow.NavigationLayoutFix.cs'
+          Replace-Exact $nav 'split into six equal columns' 'split into seven equal columns'
+          Replace-Exact $nav 'button.Name is not ("NavExplorerButton" or "NavLiveButton" or "NavEventsButton" or "NavAlarmButton" or "NavGooseButton" or "NavDiagnosticsButton")' 'button.Name is not ("NavExplorerButton" or "NavLiveButton" or "NavEventsButton" or "NavAlarmButton" or "NavGooseButton" or "NavDiagnosticsButton" or "NavNativeFatButton")'
+          Replace-Exact $nav '            window.FindName("NavDiagnosticsButton") as Button`n        ];' '            window.FindName("NavDiagnosticsButton") as Button,`n            window.FindName("NavNativeFatButton") as Button`n        ];'
+          Replace-Exact $nav 'six equal star columns' 'seven equal star columns'
+          Replace-Exact $nav 'contentWidth / 6d' 'contentWidth / 7d' 2
+          Replace-Exact $nav 'Math.Clamp(tabs.SelectedIndex, 0, 5)' 'Math.Clamp(tabs.SelectedIndex, 0, 6)'
+
+          $sas = 'SasOperationalUiPolicy.cs'
+          Replace-Exact $sas '"NavExplorerButton", "NavLiveButton", "NavEventsButton", "NavAlarmButton", "NavGooseButton", "NavDiagnosticsButton"' '"NavExplorerButton", "NavLiveButton", "NavEventsButton", "NavAlarmButton", "NavGooseButton", "NavDiagnosticsButton", "NavNativeFatButton"'
+
+          $tests = 'tests/ARSAS.Tests/AlarmAnnunciatorIntegrationRegressionTests.cs'
+          Replace-Exact $tests 'Header_UsesSixWorkflowDestinations_WithoutDuplicateRuntimeStatusChips' 'Header_UsesSevenWorkflowDestinations_WithoutDuplicateRuntimeStatusChips'
+          Replace-Exact $tests 'Assert.Equal(6, navColumns);' 'Assert.Equal(7, navColumns);'
+          Replace-Exact $tests '            (string?)button.Attribute(x + "Name") == "NavDiagnosticsButton" &&`n            (string?)button.Attribute("Tag") == "5");' '            (string?)button.Attribute(x + "Name") == "NavDiagnosticsButton" &&`n            (string?)button.Attribute("Tag") == "5");`n        Assert.Contains(navGrid.Descendants(p + "Button"), button =>`n            (string?)button.Attribute(x + "Name") == "NavNativeFatButton" &&`n            (string?)button.Attribute("Tag") == "6" &&`n            (string?)button.Attribute("Content") == "FAT");'
+          Replace-Exact $tests '\"NavExplorerButton\", \"NavLiveButton\", \"NavEventsButton\", \"NavAlarmButton\", \"NavGooseButton\", \"NavDiagnosticsButton\"' '\"NavExplorerButton\", \"NavLiveButton\", \"NavEventsButton\", \"NavAlarmButton\", \"NavGooseButton\", \"NavDiagnosticsButton\", \"NavNativeFatButton\"'
+          Replace-Exact $tests 'NavigationAndDiagnosticsUseSixTabGeometry' 'NavigationAndDiagnosticsUseSevenTabGeometry'
+          Replace-Exact $tests 'Assert.Contains("contentWidth / 6d", navigation, StringComparison.Ordinal);' 'Assert.Contains("contentWidth / 7d", navigation, StringComparison.Ordinal);'
+          Replace-Exact $tests 'Assert.Contains("Math.Clamp(tabs.SelectedIndex, 0, 5)", navigation, StringComparison.Ordinal);' 'Assert.Contains("Math.Clamp(tabs.SelectedIndex, 0, 6)", navigation, StringComparison.Ordinal);'
+          Replace-Exact $tests 'Assert.Contains("NavAlarmButton", navigation, StringComparison.Ordinal);' 'Assert.Contains("NavAlarmButton", navigation, StringComparison.Ordinal);`n        Assert.Contains("NavNativeFatButton", navigation, StringComparison.Ordinal);'
+          Replace-Exact $tests 'Assert.Contains("Math.Clamp(index, 0, 5)", main, StringComparison.Ordinal);' 'Assert.Contains("Math.Clamp(index, 0, 6)", main, StringComparison.Ordinal);'
+
+          # Fail closed if any six-slot geometry remains in the two navigation owners.
+          $navAfter = Get-Content $nav -Raw
+          $sasAfter = Get-Content $sas -Raw
+          if ($navAfter -match 'contentWidth / 6d' -or $navAfter -match 'SelectedIndex, 0, 5' -or $sasAfter -notmatch 'NavNativeFatButton') {
+            throw 'Seven-slot consistency postcondition failed.'
+          }
+
+          Remove-Item '.github/workflows/fat-m1-seven-slot-guarded-fix.yml'
+
+          git config user.name 'github-actions[bot]'
+          git config user.email '41898282+github-actions[bot]@users.noreply.github.com'
+          git add MainWindow.NavigationLayoutFix.cs SasOperationalUiPolicy.cs tests/ARSAS.Tests/AlarmAnnunciatorIntegrationRegressionTests.cs .github/workflows/fat-m1-seven-slot-guarded-fix.yml
+          git commit -m 'fix: complete canonical seven-slot navigation ownership'
+          git push origin HEAD:fix/fat-workstation-convergence

From f2df6d093e7045603dadfb28b6624a645ccdc018 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 08:04:55 +0700
Subject: [PATCH 10/84] ci: fix guarded M1 migration newline matching

---
 .../fat-m1-seven-slot-guarded-fix.yml         | 24 +++++++++++++++----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/.github/workflows/fat-m1-seven-slot-guarded-fix.yml b/.github/workflows/fat-m1-seven-slot-guarded-fix.yml
index 8ab15ac00..38c690f85 100644
--- a/.github/workflows/fat-m1-seven-slot-guarded-fix.yml
+++ b/.github/workflows/fat-m1-seven-slot-guarded-fix.yml
@@ -24,6 +24,7 @@ jobs:
         shell: pwsh
         run: |
           $ErrorActionPreference = 'Stop'
+          $nl = [Environment]::NewLine
 
           function Replace-Exact([string]$Path, [string]$Old, [string]$New, [int]$ExpectedCount = 1) {
             $text = Get-Content $Path -Raw
@@ -38,7 +39,9 @@ jobs:
           $nav = 'MainWindow.NavigationLayoutFix.cs'
           Replace-Exact $nav 'split into six equal columns' 'split into seven equal columns'
           Replace-Exact $nav 'button.Name is not ("NavExplorerButton" or "NavLiveButton" or "NavEventsButton" or "NavAlarmButton" or "NavGooseButton" or "NavDiagnosticsButton")' 'button.Name is not ("NavExplorerButton" or "NavLiveButton" or "NavEventsButton" or "NavAlarmButton" or "NavGooseButton" or "NavDiagnosticsButton" or "NavNativeFatButton")'
-          Replace-Exact $nav '            window.FindName("NavDiagnosticsButton") as Button`n        ];' '            window.FindName("NavDiagnosticsButton") as Button,`n            window.FindName("NavNativeFatButton") as Button`n        ];'
+          $oldNavTail = '            window.FindName("NavDiagnosticsButton") as Button'
+          $newNavTail = $oldNavTail + ',' + $nl + '            window.FindName("NavNativeFatButton") as Button'
+          Replace-Exact $nav $oldNavTail $newNavTail
           Replace-Exact $nav 'six equal star columns' 'seven equal star columns'
           Replace-Exact $nav 'contentWidth / 6d' 'contentWidth / 7d' 2
           Replace-Exact $nav 'Math.Clamp(tabs.SelectedIndex, 0, 5)' 'Math.Clamp(tabs.SelectedIndex, 0, 6)'
@@ -49,18 +52,29 @@ jobs:
           $tests = 'tests/ARSAS.Tests/AlarmAnnunciatorIntegrationRegressionTests.cs'
           Replace-Exact $tests 'Header_UsesSixWorkflowDestinations_WithoutDuplicateRuntimeStatusChips' 'Header_UsesSevenWorkflowDestinations_WithoutDuplicateRuntimeStatusChips'
           Replace-Exact $tests 'Assert.Equal(6, navColumns);' 'Assert.Equal(7, navColumns);'
-          Replace-Exact $tests '            (string?)button.Attribute(x + "Name") == "NavDiagnosticsButton" &&`n            (string?)button.Attribute("Tag") == "5");' '            (string?)button.Attribute(x + "Name") == "NavDiagnosticsButton" &&`n            (string?)button.Attribute("Tag") == "5");`n        Assert.Contains(navGrid.Descendants(p + "Button"), button =>`n            (string?)button.Attribute(x + "Name") == "NavNativeFatButton" &&`n            (string?)button.Attribute("Tag") == "6" &&`n            (string?)button.Attribute("Content") == "FAT");'
+          $tag5 = '            (string?)button.Attribute("Tag") == "5");'
+          $fatAssert = $tag5 + $nl + '        Assert.Contains(navGrid.Descendants(p + "Button"), button =>' + $nl + '            (string?)button.Attribute(x + "Name") == "NavNativeFatButton" &&' + $nl + '            (string?)button.Attribute("Tag") == "6" &&' + $nl + '            (string?)button.Attribute("Content") == "FAT");'
+          Replace-Exact $tests $tag5 $fatAssert
           Replace-Exact $tests '\"NavExplorerButton\", \"NavLiveButton\", \"NavEventsButton\", \"NavAlarmButton\", \"NavGooseButton\", \"NavDiagnosticsButton\"' '\"NavExplorerButton\", \"NavLiveButton\", \"NavEventsButton\", \"NavAlarmButton\", \"NavGooseButton\", \"NavDiagnosticsButton\", \"NavNativeFatButton\"'
           Replace-Exact $tests 'NavigationAndDiagnosticsUseSixTabGeometry' 'NavigationAndDiagnosticsUseSevenTabGeometry'
           Replace-Exact $tests 'Assert.Contains("contentWidth / 6d", navigation, StringComparison.Ordinal);' 'Assert.Contains("contentWidth / 7d", navigation, StringComparison.Ordinal);'
           Replace-Exact $tests 'Assert.Contains("Math.Clamp(tabs.SelectedIndex, 0, 5)", navigation, StringComparison.Ordinal);' 'Assert.Contains("Math.Clamp(tabs.SelectedIndex, 0, 6)", navigation, StringComparison.Ordinal);'
-          Replace-Exact $tests 'Assert.Contains("NavAlarmButton", navigation, StringComparison.Ordinal);' 'Assert.Contains("NavAlarmButton", navigation, StringComparison.Ordinal);`n        Assert.Contains("NavNativeFatButton", navigation, StringComparison.Ordinal);'
+          $alarmAssert = '        Assert.Contains("NavAlarmButton", navigation, StringComparison.Ordinal);'
+          $alarmAndFatAssert = $alarmAssert + $nl + '        Assert.Contains("NavNativeFatButton", navigation, StringComparison.Ordinal);'
+          Replace-Exact $tests $alarmAssert $alarmAndFatAssert
           Replace-Exact $tests 'Assert.Contains("Math.Clamp(index, 0, 5)", main, StringComparison.Ordinal);' 'Assert.Contains("Math.Clamp(index, 0, 6)", main, StringComparison.Ordinal);'
 
-          # Fail closed if any six-slot geometry remains in the two navigation owners.
+          # Fail closed if any six-slot geometry remains in the navigation owners,
+          # or if FAT is missing from the ballistic button set / regression contract.
           $navAfter = Get-Content $nav -Raw
           $sasAfter = Get-Content $sas -Raw
-          if ($navAfter -match 'contentWidth / 6d' -or $navAfter -match 'SelectedIndex, 0, 5' -or $sasAfter -notmatch 'NavNativeFatButton') {
+          $testsAfter = Get-Content $tests -Raw
+          if ($navAfter -match 'contentWidth / 6d' -or
+              $navAfter -match 'SelectedIndex, 0, 5' -or
+              $navAfter -notmatch 'NavNativeFatButton' -or
+              $sasAfter -notmatch 'NavNativeFatButton' -or
+              $testsAfter -notmatch 'Assert.Equal\(7, navColumns\)' -or
+              $testsAfter -notmatch 'NavigationAndDiagnosticsUseSevenTabGeometry') {
             throw 'Seven-slot consistency postcondition failed.'
           }
 

From b3058ce16c6fc207e2da3d74e06b39f6b41dd95f Mon Sep 17 00:00:00 2001
From: "github-actions[bot]"
 <41898282+github-actions[bot]@users.noreply.github.com>
Date: Thu, 10 Sep 2026 01:05:07 +0000
Subject: [PATCH 11/84] fix: complete canonical seven-slot navigation ownership

---
 .../fat-m1-seven-slot-guarded-fix.yml         | 87 -------------------
 MainWindow.NavigationLayoutFix.cs             | 15 ++--
 SasOperationalUiPolicy.cs                     |  2 +-
 ...rmAnnunciatorIntegrationRegressionTests.cs | 19 ++--
 4 files changed, 21 insertions(+), 102 deletions(-)
 delete mode 100644 .github/workflows/fat-m1-seven-slot-guarded-fix.yml

diff --git a/.github/workflows/fat-m1-seven-slot-guarded-fix.yml b/.github/workflows/fat-m1-seven-slot-guarded-fix.yml
deleted file mode 100644
index 38c690f85..000000000
--- a/.github/workflows/fat-m1-seven-slot-guarded-fix.yml
+++ /dev/null
@@ -1,87 +0,0 @@
-name: FAT M1 seven-slot guarded consistency fix
-
-on:
-  push:
-    branches:
-      - fix/fat-workstation-convergence
-    paths:
-      - .github/workflows/fat-m1-seven-slot-guarded-fix.yml
-
-permissions:
-  contents: write
-
-jobs:
-  migrate:
-    runs-on: windows-latest
-    steps:
-      - name: Checkout staging branch
-        uses: actions/checkout@v4
-        with:
-          ref: fix/fat-workstation-convergence
-          fetch-depth: 0
-
-      - name: Apply guarded seven-slot consistency migration
-        shell: pwsh
-        run: |
-          $ErrorActionPreference = 'Stop'
-          $nl = [Environment]::NewLine
-
-          function Replace-Exact([string]$Path, [string]$Old, [string]$New, [int]$ExpectedCount = 1) {
-            $text = Get-Content $Path -Raw
-            $count = ([regex]::Matches($text, [regex]::Escape($Old))).Count
-            if ($count -ne $ExpectedCount) {
-              throw "Guard failed for $Path. Expected $ExpectedCount occurrence(s) of [$Old], found $count."
-            }
-            $text = $text.Replace($Old, $New)
-            Set-Content -Path $Path -Value $text -NoNewline -Encoding utf8
-          }
-
-          $nav = 'MainWindow.NavigationLayoutFix.cs'
-          Replace-Exact $nav 'split into six equal columns' 'split into seven equal columns'
-          Replace-Exact $nav 'button.Name is not ("NavExplorerButton" or "NavLiveButton" or "NavEventsButton" or "NavAlarmButton" or "NavGooseButton" or "NavDiagnosticsButton")' 'button.Name is not ("NavExplorerButton" or "NavLiveButton" or "NavEventsButton" or "NavAlarmButton" or "NavGooseButton" or "NavDiagnosticsButton" or "NavNativeFatButton")'
-          $oldNavTail = '            window.FindName("NavDiagnosticsButton") as Button'
-          $newNavTail = $oldNavTail + ',' + $nl + '            window.FindName("NavNativeFatButton") as Button'
-          Replace-Exact $nav $oldNavTail $newNavTail
-          Replace-Exact $nav 'six equal star columns' 'seven equal star columns'
-          Replace-Exact $nav 'contentWidth / 6d' 'contentWidth / 7d' 2
-          Replace-Exact $nav 'Math.Clamp(tabs.SelectedIndex, 0, 5)' 'Math.Clamp(tabs.SelectedIndex, 0, 6)'
-
-          $sas = 'SasOperationalUiPolicy.cs'
-          Replace-Exact $sas '"NavExplorerButton", "NavLiveButton", "NavEventsButton", "NavAlarmButton", "NavGooseButton", "NavDiagnosticsButton"' '"NavExplorerButton", "NavLiveButton", "NavEventsButton", "NavAlarmButton", "NavGooseButton", "NavDiagnosticsButton", "NavNativeFatButton"'
-
-          $tests = 'tests/ARSAS.Tests/AlarmAnnunciatorIntegrationRegressionTests.cs'
-          Replace-Exact $tests 'Header_UsesSixWorkflowDestinations_WithoutDuplicateRuntimeStatusChips' 'Header_UsesSevenWorkflowDestinations_WithoutDuplicateRuntimeStatusChips'
-          Replace-Exact $tests 'Assert.Equal(6, navColumns);' 'Assert.Equal(7, navColumns);'
-          $tag5 = '            (string?)button.Attribute("Tag") == "5");'
-          $fatAssert = $tag5 + $nl + '        Assert.Contains(navGrid.Descendants(p + "Button"), button =>' + $nl + '            (string?)button.Attribute(x + "Name") == "NavNativeFatButton" &&' + $nl + '            (string?)button.Attribute("Tag") == "6" &&' + $nl + '            (string?)button.Attribute("Content") == "FAT");'
-          Replace-Exact $tests $tag5 $fatAssert
-          Replace-Exact $tests '\"NavExplorerButton\", \"NavLiveButton\", \"NavEventsButton\", \"NavAlarmButton\", \"NavGooseButton\", \"NavDiagnosticsButton\"' '\"NavExplorerButton\", \"NavLiveButton\", \"NavEventsButton\", \"NavAlarmButton\", \"NavGooseButton\", \"NavDiagnosticsButton\", \"NavNativeFatButton\"'
-          Replace-Exact $tests 'NavigationAndDiagnosticsUseSixTabGeometry' 'NavigationAndDiagnosticsUseSevenTabGeometry'
-          Replace-Exact $tests 'Assert.Contains("contentWidth / 6d", navigation, StringComparison.Ordinal);' 'Assert.Contains("contentWidth / 7d", navigation, StringComparison.Ordinal);'
-          Replace-Exact $tests 'Assert.Contains("Math.Clamp(tabs.SelectedIndex, 0, 5)", navigation, StringComparison.Ordinal);' 'Assert.Contains("Math.Clamp(tabs.SelectedIndex, 0, 6)", navigation, StringComparison.Ordinal);'
-          $alarmAssert = '        Assert.Contains("NavAlarmButton", navigation, StringComparison.Ordinal);'
-          $alarmAndFatAssert = $alarmAssert + $nl + '        Assert.Contains("NavNativeFatButton", navigation, StringComparison.Ordinal);'
-          Replace-Exact $tests $alarmAssert $alarmAndFatAssert
-          Replace-Exact $tests 'Assert.Contains("Math.Clamp(index, 0, 5)", main, StringComparison.Ordinal);' 'Assert.Contains("Math.Clamp(index, 0, 6)", main, StringComparison.Ordinal);'
-
-          # Fail closed if any six-slot geometry remains in the navigation owners,
-          # or if FAT is missing from the ballistic button set / regression contract.
-          $navAfter = Get-Content $nav -Raw
-          $sasAfter = Get-Content $sas -Raw
-          $testsAfter = Get-Content $tests -Raw
-          if ($navAfter -match 'contentWidth / 6d' -or
-              $navAfter -match 'SelectedIndex, 0, 5' -or
-              $navAfter -notmatch 'NavNativeFatButton' -or
-              $sasAfter -notmatch 'NavNativeFatButton' -or
-              $testsAfter -notmatch 'Assert.Equal\(7, navColumns\)' -or
-              $testsAfter -notmatch 'NavigationAndDiagnosticsUseSevenTabGeometry') {
-            throw 'Seven-slot consistency postcondition failed.'
-          }
-
-          Remove-Item '.github/workflows/fat-m1-seven-slot-guarded-fix.yml'
-
-          git config user.name 'github-actions[bot]'
-          git config user.email '41898282+github-actions[bot]@users.noreply.github.com'
-          git add MainWindow.NavigationLayoutFix.cs SasOperationalUiPolicy.cs tests/ARSAS.Tests/AlarmAnnunciatorIntegrationRegressionTests.cs .github/workflows/fat-m1-seven-slot-guarded-fix.yml
-          git commit -m 'fix: complete canonical seven-slot navigation ownership'
-          git push origin HEAD:fix/fat-workstation-convergence
diff --git a/MainWindow.NavigationLayoutFix.cs b/MainWindow.NavigationLayoutFix.cs
index fe2e8325f..55e5b0f0b 100644
--- a/MainWindow.NavigationLayoutFix.cs
+++ b/MainWindow.NavigationLayoutFix.cs
@@ -10,7 +10,7 @@ namespace ArIED61850Tester;
 /// <summary>
 /// Owns the responsive geometry of the MainWindow workflow header.
 ///
-/// The original XAML used a 760 px shell split into six equal columns while the
+/// The original XAML used a 760 px shell split into seven equal columns while the
 /// selection pill moved in hard-coded 150 px steps. That was barely large enough for
 /// short labels and clipped "IEC 61850 Explorer" / "GOOSE Subscriber" once the center
 /// workspace switch and live connection/status chips were also present. This behavior
@@ -93,7 +93,7 @@ private static void OnMainWindowButtonClick(object sender, RoutedEventArgs e)
         if (sender is not MainWindow window || e.Source is not Button button)
             return;
 
-        if (button.Name is not ("NavExplorerButton" or "NavLiveButton" or "NavEventsButton" or "NavAlarmButton" or "NavGooseButton" or "NavDiagnosticsButton"))
+        if (button.Name is not ("NavExplorerButton" or "NavLiveButton" or "NavEventsButton" or "NavAlarmButton" or "NavGooseButton" or "NavDiagnosticsButton" or "NavNativeFatButton"))
             return;
 
         // A repeated click on the already-selected tab does not raise SelectionChanged,
@@ -195,7 +195,8 @@ private static void ApplyResponsiveLayout(MainWindow window)
             window.FindName("NavEventsButton") as Button,
             window.FindName("NavAlarmButton") as Button,
             window.FindName("NavGooseButton") as Button,
-            window.FindName("NavDiagnosticsButton") as Button
+            window.FindName("NavDiagnosticsButton") as Button,
+            window.FindName("NavNativeFatButton") as Button
         ];
 
     private static void UpdatePillGeometry(MainWindow window, double shellWidth)
@@ -204,9 +205,9 @@ private static void UpdatePillGeometry(MainWindow window, double shellWidth)
             return;
 
         // Border padding owns 10 px horizontally. The nav grid itself is divided into
-        // six equal star columns, so this is the exact width used by each button cell.
+        // seven equal star columns, so this is the exact width used by each button cell.
         var contentWidth = Math.Max(0d, shellWidth - 10d);
-        var cellWidth = contentWidth / 6d;
+        var cellWidth = contentWidth / 7d;
         pill.Width = Math.Max(1d, cellWidth - 2d);
         pill.Height = 36;
         pill.HorizontalAlignment = HorizontalAlignment.Left;
@@ -279,8 +280,8 @@ private static void PositionPill(MainWindow window, bool animate)
         if (contentWidth <= 0d)
             contentWidth = Math.Max(0d, shell.Width - shell.Padding.Left - shell.Padding.Right);
 
-        var cellWidth = contentWidth / 6d;
-        var target = Math.Clamp(tabs.SelectedIndex, 0, 5) * cellWidth;
+        var cellWidth = contentWidth / 7d;
+        var target = Math.Clamp(tabs.SelectedIndex, 0, 6) * cellWidth;
         pill.Width = Math.Max(1d, cellWidth - 2d);
 
         translate.BeginAnimation(TranslateTransform.XProperty, null);
diff --git a/SasOperationalUiPolicy.cs b/SasOperationalUiPolicy.cs
index cd9cd10d7..8c63dbce2 100644
--- a/SasOperationalUiPolicy.cs
+++ b/SasOperationalUiPolicy.cs
@@ -24,7 +24,7 @@ internal static class SasOperationalUiPolicy
     private static readonly ConditionalWeakTable<object, object> FilteredViews = new();
     private static readonly string[] NavigationButtonNames =
     {
-        "NavExplorerButton", "NavLiveButton", "NavEventsButton", "NavAlarmButton", "NavGooseButton", "NavDiagnosticsButton"
+        "NavExplorerButton", "NavLiveButton", "NavEventsButton", "NavAlarmButton", "NavGooseButton", "NavDiagnosticsButton", "NavNativeFatButton"
     };
 
     [ModuleInitializer]
diff --git a/tests/ARSAS.Tests/AlarmAnnunciatorIntegrationRegressionTests.cs b/tests/ARSAS.Tests/AlarmAnnunciatorIntegrationRegressionTests.cs
index f7811ae2f..75379f03c 100644
--- a/tests/ARSAS.Tests/AlarmAnnunciatorIntegrationRegressionTests.cs
+++ b/tests/ARSAS.Tests/AlarmAnnunciatorIntegrationRegressionTests.cs
@@ -5,7 +5,7 @@ namespace ARSAS.Tests;
 public sealed class AlarmAnnunciatorIntegrationRegressionTests
 {
     [Fact]
-    public void Header_UsesSixWorkflowDestinations_WithoutDuplicateRuntimeStatusChips()
+    public void Header_UsesSevenWorkflowDestinations_WithoutDuplicateRuntimeStatusChips()
     {
         var document = XDocument.Parse(File.ReadAllText(FindRepoFile("MainWindow.xaml")));
         XNamespace p = "http://schemas.microsoft.com/winfx/2006/xaml/presentation";
@@ -20,7 +20,7 @@ public void Header_UsesSixWorkflowDestinations_WithoutDuplicateRuntimeStatusChip
         var navColumns = navGrid.Element(p + "Grid.ColumnDefinitions")?
             .Elements(p + "ColumnDefinition").Count() ?? 0;
 
-        Assert.Equal(6, navColumns);
+        Assert.Equal(7, navColumns);
         Assert.Contains(navGrid.Descendants(p + "Button"), button =>
             (string?)button.Attribute(x + "Name") == "NavAlarmButton" &&
             (string?)button.Attribute("Tag") == "3" &&
@@ -31,6 +31,10 @@ public void Header_UsesSixWorkflowDestinations_WithoutDuplicateRuntimeStatusChip
         Assert.Contains(navGrid.Descendants(p + "Button"), button =>
             (string?)button.Attribute(x + "Name") == "NavDiagnosticsButton" &&
             (string?)button.Attribute("Tag") == "5");
+        Assert.Contains(navGrid.Descendants(p + "Button"), button =>
+            (string?)button.Attribute(x + "Name") == "NavNativeFatButton" &&
+            (string?)button.Attribute("Tag") == "6" &&
+            (string?)button.Attribute("Content") == "FAT");
 
         var headerSource = header.ToString(SaveOptions.DisableFormatting);
         Assert.DoesNotContain("ConnectionInsightText", headerSource, StringComparison.Ordinal);
@@ -46,7 +50,7 @@ public void BallisticNavbar_AppliesTheSameCapsuleContractToAlarm()
     {
         var source = File.ReadAllText(FindRepoFile("SasOperationalUiPolicy.cs"));
 
-        Assert.Contains("\"NavExplorerButton\", \"NavLiveButton\", \"NavEventsButton\", \"NavAlarmButton\", \"NavGooseButton\", \"NavDiagnosticsButton\"", source, StringComparison.Ordinal);
+        Assert.Contains("\"NavExplorerButton\", \"NavLiveButton\", \"NavEventsButton\", \"NavAlarmButton\", \"NavGooseButton\", \"NavDiagnosticsButton\", \"NavNativeFatButton\"", source, StringComparison.Ordinal);
         Assert.Contains("UpdateNavigation(buttons, tabs.SelectedIndex", source, StringComparison.Ordinal);
         Assert.Contains("buttons[index].Background = selected ? AccentGradient()", source, StringComparison.Ordinal);
     }
@@ -122,17 +126,18 @@ public void Annunciator_FlashAndAckWorkAreBoundedToVisibleIedOrIedRail()
     }
 
     [Fact]
-    public void NavigationAndDiagnosticsUseSixTabGeometry()
+    public void NavigationAndDiagnosticsUseSevenTabGeometry()
     {
         var navigation = File.ReadAllText(FindRepoFile("MainWindow.NavigationLayoutFix.cs"));
         var main = File.ReadAllText(FindRepoFile("MainWindow.xaml.cs"));
 
-        Assert.Contains("contentWidth / 6d", navigation, StringComparison.Ordinal);
-        Assert.Contains("Math.Clamp(tabs.SelectedIndex, 0, 5)", navigation, StringComparison.Ordinal);
+        Assert.Contains("contentWidth / 7d", navigation, StringComparison.Ordinal);
+        Assert.Contains("Math.Clamp(tabs.SelectedIndex, 0, 6)", navigation, StringComparison.Ordinal);
         Assert.Contains("NavAlarmButton", navigation, StringComparison.Ordinal);
+        Assert.Contains("NavNativeFatButton", navigation, StringComparison.Ordinal);
         Assert.Contains("MainTabs.SelectedIndex == 4", main, StringComparison.Ordinal);
         Assert.Contains("MainTabs.SelectedIndex == 5", main, StringComparison.Ordinal);
-        Assert.Contains("Math.Clamp(index, 0, 5)", main, StringComparison.Ordinal);
+        Assert.Contains("Math.Clamp(index, 0, 6)", main, StringComparison.Ordinal);
     }
 
     [Fact]

From acf76cd0da0c321e8dc04dff94a8ced3bccad5c7 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 08:06:43 +0700
Subject: [PATCH 12/84] docs: lock canonical seven-slot FAT navigation
 invariant

---
 docs/FAT_ENGINEERING_WORKSTATION_CONTRACT.md | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/docs/FAT_ENGINEERING_WORKSTATION_CONTRACT.md b/docs/FAT_ENGINEERING_WORKSTATION_CONTRACT.md
index 63217aceb..713da2656 100644
--- a/docs/FAT_ENGINEERING_WORKSTATION_CONTRACT.md
+++ b/docs/FAT_ENGINEERING_WORKSTATION_CONTRACT.md
@@ -28,9 +28,9 @@ Engineering navigation has exactly seven destinations in this order:
 6. Diagnostics
 7. FAT
 
-There must be one navigation owner. Do not reintroduce a second `ModuleInitializer` / `ApplicationIdle` parity layer that fights the canonical navigation state.
+There must be one canonical navigation owner. Do not reintroduce a second `ModuleInitializer` / `ApplicationIdle` parity layer that fights the canonical navigation state.
 
-Target end-state: the FAT button and FAT `TabItem` are literal XAML siblings of the other six destinations and use the same `SegmentedNavButton` style resource.
+M1 locks FAT as a literal seventh XAML sibling using the same `SegmentedNavButton` contract. Every responsive/navigation presentation layer must consume the same seven destinations: MainWindow index range is `0..6`, selection geometry divides the available navigation width into seven equal slots, and ballistic navigation styling includes `NavNativeFatButton`. Regression tests must fail if any of these layers silently falls back to six-slot behavior.
 
 ## Multi-IED context invariant
 
@@ -58,7 +58,7 @@ Target reusable structure:
 - `FatReportPreviewView`: canonical production A4 preview presentation.
 - `IoListTestingWindow`: legacy standalone shell that may host the reusable views for compatibility, but must not be the presentation/lifecycle owner of the Engineering FAT tab.
 
-The Engineering FAT tab must eventually own a permanent FAT visual surface. Selecting FAT should only switch workstation content; it must not require `Window.Show -> Loaded -> detach/reparent`.
+The Engineering FAT tab must own a permanent FAT visual surface. Selecting FAT should only switch workstation content; it must not require `Window.Show -> Loaded -> detach/reparent`.
 
 ## Report preview invariant
 

From 1a0d3dbb346d2a8ddba0bf8d47c408836aae9d01 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 08:11:39 +0700
Subject: [PATCH 13/84] test: lock seven-cell responsive navigation geometry

---
 .../MainWindowTopBarLayoutRegressionTests.cs          | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/tests/ARSAS.Tests/MainWindowTopBarLayoutRegressionTests.cs b/tests/ARSAS.Tests/MainWindowTopBarLayoutRegressionTests.cs
index 67a83f8a4..7a2a4aca7 100644
--- a/tests/ARSAS.Tests/MainWindowTopBarLayoutRegressionTests.cs
+++ b/tests/ARSAS.Tests/MainWindowTopBarLayoutRegressionTests.cs
@@ -3,7 +3,7 @@ namespace ARSAS.Tests;
 public sealed class MainWindowTopBarLayoutRegressionTests
 {
     [Fact]
-    public void NavigationLayout_UsesResponsiveWidthsAndConsistentSixDestinationLabels()
+    public void NavigationLayout_UsesResponsiveWidthsAndConsistentSevenDestinationGeometry()
     {
         var source = File.ReadAllText(FindRepoFile("MainWindow.NavigationLayoutFix.cs"));
 
@@ -14,20 +14,22 @@ public void NavigationLayout_UsesResponsiveWidthsAndConsistentSixDestinationLabe
         Assert.Contains("\"Alarm\"", source, StringComparison.Ordinal);
         Assert.DoesNotContain("\"Alarm Annunciator\"", source, StringComparison.Ordinal);
         Assert.Contains("\"GOOSE Subscriber\"", source, StringComparison.Ordinal);
+        Assert.Contains("NavNativeFatButton", source, StringComparison.Ordinal);
         Assert.Contains("var labels = wide ? FullLabels : CompactLabels", source, StringComparison.Ordinal);
     }
 
     [Fact]
-    public void SelectionPill_IsDerivedFromActualSixCellNavWidth_NotFixed150Pixels()
+    public void SelectionPill_IsDerivedFromActualSevenCellNavWidth_NotFixed150Pixels()
     {
         var source = File.ReadAllText(FindRepoFile("MainWindow.NavigationLayoutFix.cs"));
 
-        Assert.Contains("var cellWidth = contentWidth / 6d", source, StringComparison.Ordinal);
-        Assert.Contains("Math.Clamp(tabs.SelectedIndex, 0, 5) * cellWidth", source, StringComparison.Ordinal);
+        Assert.Contains("var cellWidth = contentWidth / 7d", source, StringComparison.Ordinal);
+        Assert.Contains("Math.Clamp(tabs.SelectedIndex, 0, 6) * cellWidth", source, StringComparison.Ordinal);
         Assert.Contains("pill.Width = Math.Max(1d, cellWidth - 2d)", source, StringComparison.Ordinal);
         Assert.Contains("FindName(\"WorkflowPillTranslate\") as TranslateTransform", source, StringComparison.Ordinal);
         Assert.Contains("pill.RenderTransform is TransformGroup", source, StringComparison.Ordinal);
         Assert.DoesNotContain("* 150d", source, StringComparison.Ordinal);
+        Assert.DoesNotContain("contentWidth / 6d", source, StringComparison.Ordinal);
         Assert.DoesNotContain("contentWidth / 5d", source, StringComparison.Ordinal);
     }
 
@@ -41,6 +43,7 @@ public void ResponsiveCorrection_RunsAfterSelectionResizeAndRepeatedNavClick()
         Assert.Contains("Button.ClickEvent", source, StringComparison.Ordinal);
         Assert.Contains("OnMainWindowButtonClick", source, StringComparison.Ordinal);
         Assert.Contains("NavAlarmButton", source, StringComparison.Ordinal);
+        Assert.Contains("NavNativeFatButton", source, StringComparison.Ordinal);
         Assert.Contains("A repeated click on the already-selected tab", source, StringComparison.Ordinal);
         Assert.Contains("DispatcherPriority.Loaded", source, StringComparison.Ordinal);
         Assert.Contains("DispatcherPriority.ContextIdle", source, StringComparison.Ordinal);

From 954795a46242c6b8ba6354ede5d22641699be15f Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 08:12:05 +0700
Subject: [PATCH 14/84] test: bind MainWindow navigation clamp to canonical FAT
 index

---
 .../ARSAS.Tests/AlarmAnnunciatorIntegrationRegressionTests.cs | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tests/ARSAS.Tests/AlarmAnnunciatorIntegrationRegressionTests.cs b/tests/ARSAS.Tests/AlarmAnnunciatorIntegrationRegressionTests.cs
index 75379f03c..78926fd52 100644
--- a/tests/ARSAS.Tests/AlarmAnnunciatorIntegrationRegressionTests.cs
+++ b/tests/ARSAS.Tests/AlarmAnnunciatorIntegrationRegressionTests.cs
@@ -130,6 +130,7 @@ public void NavigationAndDiagnosticsUseSevenTabGeometry()
     {
         var navigation = File.ReadAllText(FindRepoFile("MainWindow.NavigationLayoutFix.cs"));
         var main = File.ReadAllText(FindRepoFile("MainWindow.xaml.cs"));
+        var nativeFat = File.ReadAllText(FindRepoFile("MainWindow.NativeFatWorkspace.cs"));
 
         Assert.Contains("contentWidth / 7d", navigation, StringComparison.Ordinal);
         Assert.Contains("Math.Clamp(tabs.SelectedIndex, 0, 6)", navigation, StringComparison.Ordinal);
@@ -137,7 +138,8 @@ public void NavigationAndDiagnosticsUseSevenTabGeometry()
         Assert.Contains("NavNativeFatButton", navigation, StringComparison.Ordinal);
         Assert.Contains("MainTabs.SelectedIndex == 4", main, StringComparison.Ordinal);
         Assert.Contains("MainTabs.SelectedIndex == 5", main, StringComparison.Ordinal);
-        Assert.Contains("Math.Clamp(index, 0, 6)", main, StringComparison.Ordinal);
+        Assert.Contains("private const int NativeFatWorkspaceIndex = 6", nativeFat, StringComparison.Ordinal);
+        Assert.Contains("Math.Clamp(index, 0, NativeFatWorkspaceIndex)", main, StringComparison.Ordinal);
     }
 
     [Fact]

From 48504353ae4ab291c8bc07298fb2db5fb39c40dd Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 09:02:14 +0700
Subject: [PATCH 15/84] chore: stage guarded M2 permanent FAT host migration

---
 tools/fat_m2_permanent_host.py | 252 +++++++++++++++++++++++++++++++++
 1 file changed, 252 insertions(+)
 create mode 100644 tools/fat_m2_permanent_host.py

diff --git a/tools/fat_m2_permanent_host.py b/tools/fat_m2_permanent_host.py
new file mode 100644
index 000000000..a35256f1a
--- /dev/null
+++ b/tools/fat_m2_permanent_host.py
@@ -0,0 +1,252 @@
+from pathlib import Path
+import re
+
+ROOT = Path(__file__).resolve().parents[1]
+
+
+def read(path):
+    return (ROOT / path).read_text(encoding="utf-8")
+
+
+def write(path, text):
+    (ROOT / path).write_text(text, encoding="utf-8")
+
+
+def replace_once(text, old, new, label):
+    count = text.count(old)
+    if count != 1:
+        raise SystemExit(f"{label}: expected exactly 1 match, found {count}")
+    return text.replace(old, new, 1)
+
+
+# M2.1 - FAT is a permanent MainWindow host, never a launcher workflow.
+path = "MainWindow.ProductionFatTab.cs"
+s = read(path)
+s = replace_once(
+    s,
+    "        _nativeFatTab.Content = BuildProductionFatLauncher();",
+    "        _nativeFatTab.Content = BuildProductionFatPermanentHost();\n\n        // M2 prewarm starts as soon as the canonical host exists. It is deliberately\n        // independent of the currently selected tab so a valid Engineering SCL/DataSet\n        // can prepare the exact production surface before the operator first opens FAT.\n        QueueProductionFatEngineeringBootstrap();",
+    "install permanent FAT host")
+
+pattern = re.compile(
+    r"    private FrameworkElement BuildProductionFatLauncher\(\)\n    \{.*?\n    \}\n\n    private void ProductionFat_MainTabsSelectionChanged",
+    re.S,
+)
+replacement = '''    private FrameworkElement BuildProductionFatPermanentHost()
+    {
+        // This is a stable shell slot, not a launcher/form. With a valid Engineering
+        // static DataSet it is replaced in the background by the exact production FAT
+        // workspace before first navigation. With no eligible IED it remains a quiet
+        // contextual empty state and never creates an alternate FAT workflow.
+        var root = new Grid { Margin = new Thickness(0) };
+        root.Children.Add(new TextBlock
+        {
+            Text = "FAT · awaiting an Engineering IED with static DataSet scope",
+            FontSize = 12,
+            Foreground = TryFindResource("Muted") as Brush ?? Brushes.DimGray,
+            HorizontalAlignment = HorizontalAlignment.Center,
+            VerticalAlignment = VerticalAlignment.Center
+        });
+        return root;
+    }
+
+    private void ProductionFat_MainTabsSelectionChanged'''
+s, n = pattern.subn(replacement, s, count=1)
+if n != 1:
+    raise SystemExit(f"replace production launcher body: expected 1 match, found {n}")
+
+s = replace_once(
+    s,
+    "        MainTabs.SelectedIndex = NativeFatWorkspaceIndex;\n        QueueNativeFatNavigationGeometry();\n\n        // The legacy launcher hides Engineering before showing IoListTestingWindow.\n        // Once its proven central workspace is re-parented here, restore Engineering and\n        // keep the legacy Window loaded-but-hidden solely as the production controller owner.\n        IsEnabled = true;\n        if (!IsVisible)\n            Show();\n        if (WindowState == WindowState.Minimized)\n            WindowState = WindowState.Normal;\n        Activate();\n\n        SetStatus($\"FAT ready in Engineering tab · {window.Project.Ieds.Count} IED · production auto-capture workflow.\");",
+    "        // Passive mount: prewarming must never navigate, hide/show, activate, or steal\n        // focus from the operator's current Engineering destination.\n        window.RegisterEmbeddedHostCloseCleanup();\n        QueueNativeFatNavigationGeometry();\n\n        if (MainTabs.SelectedIndex == NativeFatWorkspaceIndex)\n            SetStatus($\"FAT ready in Engineering tab · {window.Project.Ieds.Count} IED · production auto-capture workflow.\");",
+    "passive production FAT mount")
+
+s = replace_once(
+    s,
+    "            _nativeFatTab.Content = BuildProductionFatLauncher();",
+    "            _nativeFatTab.Content = BuildProductionFatPermanentHost();",
+    "unmount permanent FAT host")
+write(path, s)
+
+
+# M2.2 - Bootstrap is prewarm, not post-navigation work.
+path = "MainWindow.ProductionFatEngineeringBootstrap.cs"
+s = read(path)
+s = replace_once(
+    s,
+    "        if (e.PropertyName != nameof(SelectedDevice) || MainTabs.SelectedIndex != NativeFatWorkspaceIndex)\n            return;",
+    "        if (e.PropertyName != nameof(SelectedDevice))\n            return;",
+    "selected-device prewarm gate")
+s = replace_once(
+    s,
+    "        if (!_productionFatEngineeringBootstrapInstalled || MainTabs.SelectedIndex != NativeFatWorkspaceIndex)\n            return;",
+    "        if (!_productionFatEngineeringBootstrapInstalled)\n            return;",
+    "queue prewarm gate")
+s = replace_once(
+    s,
+    "        if (_productionFatEngineeringBootstrapBusy ||\n            MainTabs.SelectedIndex != NativeFatWorkspaceIndex ||\n            !ProductionFatTabReady)",
+    "        if (_productionFatEngineeringBootstrapBusy ||\n            !ProductionFatTabReady)",
+    "ensure prewarm gate")
+write(path, s)
+
+
+# M2.3 - Establish static DataSet authority as an explicit prewarm trigger too. This
+# covers same-IED SCL refreshes where SelectedDevice itself does not change.
+path = "MainWindow.SharedSclWorkspace.cs"
+s = read(path)
+s = replace_once(
+    s,
+    "        _ = ObserveInitialStaticReportEvidenceAsync(device);",
+    "        _ = ObserveInitialStaticReportEvidenceAsync(device);\n\n        // M2 permanent FAT host: authority establishment is also a readiness trigger.\n        // This covers SCL refresh on the same SelectedDevice, where PropertyChanged for\n        // SelectedDevice would otherwise not fire.\n        QueueProductionFatEngineeringBootstrap();",
+    "static DataSet prewarm trigger")
+write(path, s)
+
+
+# M2.4 - Prepare the donor window before Show(), not from Loaded after first paint.
+path = "IoListTestingWindow.EmbeddedEngineeringHost.cs"
+s = read(path)
+anchor = "    private static void EmbeddedEngineeringFatHost_Loaded(object sender, RoutedEventArgs e)\n"
+method = '''    internal void PrepareForEmbeddedEngineeringHost()
+    {
+        // Must run before Window.Show(). A transparent/off-screen, non-activating donor
+        // cannot produce the historical black/blank compositor frame while its exact
+        // production center is being re-parented into MainWindow.
+        ShowActivated = false;
+        ShowInTaskbar = false;
+        Opacity = 0d;
+        WindowStartupLocation = WindowStartupLocation.Manual;
+        Left = -32000d;
+        Top = -32000d;
+    }
+
+'''
+if method.strip() not in s:
+    s = replace_once(s, anchor, method + anchor, "insert pre-show donor preparation")
+s = replace_once(
+    s,
+    "        window.ShowActivated = false;\n        window.ShowInTaskbar = false;\n        window.Opacity = 0d;",
+    "        window.PrepareForEmbeddedEngineeringHost();",
+    "reuse donor preparation")
+write(path, s)
+
+
+# M2.5 - The production launch path prepares donor visibility before Show and does not
+# hide MainWindow when the canonical embedded host exists.
+path = "MainWindow.IoTesting.cs"
+s = read(path)
+s = replace_once(
+    s,
+    "        var window = new IoListTestingWindow(launch.Project, controller, persistence) { Owner = this };\n        RegisterLoadedIoFatWindow(window);",
+    "        var window = new IoListTestingWindow(launch.Project, controller, persistence) { Owner = this };\n        if (ProductionFatTabReady)\n            window.PrepareForEmbeddedEngineeringHost();\n        RegisterLoadedIoFatWindow(window);",
+    "prepare donor before Show")
+s = replace_once(
+    s,
+    "        window.Closed += WindowClosed;\n        Hide();\n        window.Show();",
+    "        window.Closed += WindowClosed;\n        if (!ProductionFatTabReady)\n            Hide();\n        window.Show();",
+    "keep Engineering visible")
+write(path, s)
+
+
+# M2.6 - Keep old shadow-Hide safety net correct while it remains until M7 cleanup.
+path = "MainWindow.ProductionFatNoFlicker.cs"
+s = read(path)
+s = replace_once(
+    s,
+    "        => _productionFatEngineeringBootstrapBusy &&\n           ProductionFatTabReady &&\n           MainTabs.SelectedIndex == NativeFatWorkspaceIndex;",
+    "        => _productionFatEngineeringBootstrapBusy &&\n           ProductionFatTabReady;",
+    "background prewarm no-flicker guard")
+write(path, s)
+
+
+# M2.7 - Update the existing architecture regression and add a focused permanent-host gate.
+path = "tests/ARSAS.Tests/ProductionFatEngineeringTabRegressionTests.cs"
+s = read(path)
+s = replace_once(
+    s,
+    "        Assert.Contains(\"MainTabs.SelectedIndex != NativeFatWorkspaceIndex\", source, StringComparison.Ordinal);",
+    "        Assert.Contains(\"QueueProductionFatEngineeringBootstrap();\", source, StringComparison.Ordinal);",
+    "update bootstrap regression")
+write(path, s)
+
+new_test = ROOT / "tests/ARSAS.Tests/ProductionFatM2PermanentHostRegressionTests.cs"
+new_test.write_text(r'''namespace ARSAS.Tests;
+
+public sealed class ProductionFatM2PermanentHostRegressionTests
+{
+    [Fact]
+    public void FatTab_IsPermanentHost_NotLauncherOrAlternateOpenSclWorkflow()
+    {
+        var source = Read("MainWindow.ProductionFatTab.cs");
+
+        Assert.Contains("BuildProductionFatPermanentHost()", source, StringComparison.Ordinal);
+        Assert.DoesNotContain("BuildProductionFatLauncher", source, StringComparison.Ordinal);
+        Assert.DoesNotContain("Open SCL for FAT", source, StringComparison.Ordinal);
+        Assert.DoesNotContain("Open ARSAS Project", source, StringComparison.Ordinal);
+        Assert.DoesNotContain("OpenSclFatTesting_Click", source, StringComparison.Ordinal);
+        Assert.DoesNotContain("OpenIoListPackage_Click", source, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void EngineeringStaticDataSet_PrewarmIsIndependentOfFatTabSelection()
+    {
+        var bootstrap = Read("MainWindow.ProductionFatEngineeringBootstrap.cs");
+        var shared = Read("MainWindow.SharedSclWorkspace.cs");
+
+        Assert.Contains("e.PropertyName != nameof(SelectedDevice)", bootstrap, StringComparison.Ordinal);
+        Assert.Contains("QueueProductionFatEngineeringBootstrap();", shared, StringComparison.Ordinal);
+        Assert.DoesNotContain("_productionFatEngineeringBootstrapBusy ||\n            MainTabs.SelectedIndex != NativeFatWorkspaceIndex", bootstrap, StringComparison.Ordinal);
+        Assert.DoesNotContain("_productionFatEngineeringBootstrapInstalled || MainTabs.SelectedIndex != NativeFatWorkspaceIndex", bootstrap, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void EmbeddedDonor_IsPreparedBeforeShow_AndMainWindowStaysVisible()
+    {
+        var launch = Read("MainWindow.IoTesting.cs");
+        var host = Read("IoListTestingWindow.EmbeddedEngineeringHost.cs");
+        var tab = Read("MainWindow.ProductionFatTab.cs");
+
+        var prepare = launch.IndexOf("window.PrepareForEmbeddedEngineeringHost();", StringComparison.Ordinal);
+        var show = launch.IndexOf("window.Show();", StringComparison.Ordinal);
+        Assert.True(prepare >= 0 && show > prepare, "Donor visibility must be prepared before Window.Show().");
+        Assert.Contains("if (!ProductionFatTabReady)\n            Hide();", launch, StringComparison.Ordinal);
+        Assert.Contains("Left = -32000d", host, StringComparison.Ordinal);
+        Assert.Contains("Opacity = 0d", host, StringComparison.Ordinal);
+        Assert.Contains("ShowActivated = false", host, StringComparison.Ordinal);
+        Assert.Contains("ShowInTaskbar = false", host, StringComparison.Ordinal);
+
+        Assert.DoesNotContain("MainTabs.SelectedIndex = NativeFatWorkspaceIndex", tab, StringComparison.Ordinal);
+        Assert.DoesNotContain("Activate();", tab, StringComparison.Ordinal);
+        Assert.DoesNotContain("if (!IsVisible)\n            Show();", tab, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void EmbeddedSurface_RemainsExactProductionGridAndPreviewSource()
+    {
+        var host = Read("IoListTestingWindow.EmbeddedEngineeringHost.cs");
+
+        Assert.Contains("InstallFatV2WorkspaceUx();", host, StringComparison.Ordinal);
+        Assert.Contains("InstallPerIedPrintPreview();", host, StringComparison.Ordinal);
+        Assert.Contains("DetachProductionFatCentralWorkspace()", host, StringComparison.Ordinal);
+        Assert.Contains("owner.MountProductionFatWorkspace(this, surface)", host, StringComparison.Ordinal);
+    }
+
+    private static string Read(string relativePath)
+        => File.ReadAllText(Path.Combine(FindRepoRoot(), relativePath));
+
+    private static string FindRepoRoot()
+    {
+        DirectoryInfo? directory = new(AppContext.BaseDirectory);
+        while (directory != null)
+        {
+            if (File.Exists(Path.Combine(directory.FullName, "MainWindow.xaml")) &&
+                Directory.Exists(Path.Combine(directory.FullName, "tests", "ARSAS.Tests")))
+                return directory.FullName;
+            directory = directory.Parent;
+        }
+
+        throw new DirectoryNotFoundException("Could not locate repository root.");
+    }
+}
+''', encoding="utf-8")
+
+print("M2 permanent FAT host migration applied successfully")

From b648186124c7b5700c387b42da3a3cdb366687a6 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 09:02:28 +0700
Subject: [PATCH 16/84] chore: run guarded M2 permanent FAT host migration

---
 .github/workflows/fat-m2-permanent-host.yml | 43 +++++++++++++++++++++
 1 file changed, 43 insertions(+)
 create mode 100644 .github/workflows/fat-m2-permanent-host.yml

diff --git a/.github/workflows/fat-m2-permanent-host.yml b/.github/workflows/fat-m2-permanent-host.yml
new file mode 100644
index 000000000..1e05436ee
--- /dev/null
+++ b/.github/workflows/fat-m2-permanent-host.yml
@@ -0,0 +1,43 @@
+name: FAT M2 permanent host migration
+
+on:
+  push:
+    branches:
+      - fix/fat-workstation-convergence
+    paths:
+      - .github/workflows/fat-m2-permanent-host.yml
+      - tools/fat_m2_permanent_host.py
+
+permissions:
+  contents: write
+
+jobs:
+  migrate:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout staging branch
+        uses: actions/checkout@v4
+        with:
+          ref: fix/fat-workstation-convergence
+          fetch-depth: 0
+
+      - name: Apply guarded M2 migration
+        run: python tools/fat_m2_permanent_host.py
+
+      - name: Remove one-shot migration helpers
+        run: |
+          rm tools/fat_m2_permanent_host.py
+          rm .github/workflows/fat-m2-permanent-host.yml
+
+      - name: Commit M2 source changes
+        shell: bash
+        run: |
+          git config user.name "github-actions[bot]"
+          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
+          git add -A
+          if git diff --cached --quiet; then
+            echo "No migration changes to commit"
+            exit 0
+          fi
+          git commit -m "feat: complete M2 permanent production FAT host"
+          git push origin HEAD:fix/fat-workstation-convergence

From 2c1a2acf15956d9847a696b8ae374cfaf3fc1fb7 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 09:04:47 +0700
Subject: [PATCH 17/84] chore: correct guarded M2 launcher occurrence check

---
 tools/fat_m2_guard_fix.py | 10 ++++++++++
 1 file changed, 10 insertions(+)
 create mode 100644 tools/fat_m2_guard_fix.py

diff --git a/tools/fat_m2_guard_fix.py b/tools/fat_m2_guard_fix.py
new file mode 100644
index 000000000..1b0a8c76c
--- /dev/null
+++ b/tools/fat_m2_guard_fix.py
@@ -0,0 +1,10 @@
+from pathlib import Path
+
+path = Path(__file__).with_name("fat_m2_permanent_host.py")
+source = path.read_text(encoding="utf-8")
+old = '''s = replace_once(\n    s,\n    "        _nativeFatTab.Content = BuildProductionFatLauncher();",\n    "        _nativeFatTab.Content = BuildProductionFatPermanentHost();\\n\\n        // M2 prewarm starts as soon as the canonical host exists. It is deliberately\\n        // independent of the currently selected tab so a valid Engineering SCL/DataSet\\n        // can prepare the exact production surface before the operator first opens FAT.\\n        QueueProductionFatEngineeringBootstrap();",\n    "install permanent FAT host")'''
+new = '''install_launcher = "        _nativeFatTab.Content = BuildProductionFatLauncher();"\nif s.count(install_launcher) != 2:\n    raise SystemExit(f"install permanent FAT host: expected install + unmount matches, found {s.count(install_launcher)}")\ns = s.replace(\n    install_launcher,\n    "        _nativeFatTab.Content = BuildProductionFatPermanentHost();\\n\\n        // M2 prewarm starts as soon as the canonical host exists. It is deliberately\\n        // independent of the currently selected tab so a valid Engineering SCL/DataSet\\n        // can prepare the exact production surface before the operator first opens FAT.\\n        QueueProductionFatEngineeringBootstrap();",\n    1)'''
+if source.count(old) != 1:
+    raise SystemExit(f"guard fixer expected one original install block, found {source.count(old)}")
+path.write_text(source.replace(old, new, 1), encoding="utf-8")
+print("M2 guard corrected: launcher install/unmount pair distinguished")

From 523d8abdccd53d2ffa19f32c57ed2cacdeb18a80 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 09:04:59 +0700
Subject: [PATCH 18/84] chore: rerun guarded M2 migration with precise launcher
 target

---
 .../workflows/fat-m2-permanent-host-v2.yml    | 43 +++++++++++++++++++
 1 file changed, 43 insertions(+)
 create mode 100644 .github/workflows/fat-m2-permanent-host-v2.yml

diff --git a/.github/workflows/fat-m2-permanent-host-v2.yml b/.github/workflows/fat-m2-permanent-host-v2.yml
new file mode 100644
index 000000000..bc0f1d687
--- /dev/null
+++ b/.github/workflows/fat-m2-permanent-host-v2.yml
@@ -0,0 +1,43 @@
+name: FAT M2 permanent host migration v2
+
+on:
+  push:
+    branches:
+      - fix/fat-workstation-convergence
+    paths:
+      - .github/workflows/fat-m2-permanent-host-v2.yml
+      - tools/fat_m2_guard_fix.py
+
+permissions:
+  contents: write
+
+jobs:
+  migrate:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout staging branch
+        uses: actions/checkout@v4
+        with:
+          ref: fix/fat-workstation-convergence
+          fetch-depth: 0
+
+      - name: Correct guard and apply M2 migration
+        run: |
+          python tools/fat_m2_guard_fix.py
+          python tools/fat_m2_permanent_host.py
+
+      - name: Remove one-shot migration helpers
+        run: |
+          rm tools/fat_m2_guard_fix.py
+          rm tools/fat_m2_permanent_host.py
+          rm .github/workflows/fat-m2-permanent-host-v2.yml
+          rm .github/workflows/fat-m2-permanent-host.yml
+
+      - name: Commit M2 source changes
+        shell: bash
+        run: |
+          git config user.name "github-actions[bot]"
+          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
+          git add -A
+          git commit -m "feat: complete M2 permanent production FAT host"
+          git push origin HEAD:fix/fat-workstation-convergence

From b8859655e548ea20749c6811bebb788e86bf1718 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]"
 <41898282+github-actions[bot]@users.noreply.github.com>
Date: Thu, 10 Sep 2026 02:05:08 +0000
Subject: [PATCH 19/84] feat: complete M2 permanent production FAT host

---
 .../workflows/fat-m2-permanent-host-v2.yml    |  43 ---
 .github/workflows/fat-m2-permanent-host.yml   |  43 ---
 ...stTestingWindow.EmbeddedEngineeringHost.cs |  17 +-
 MainWindow.IoTesting.cs                       |   5 +-
 ...indow.ProductionFatEngineeringBootstrap.cs |   5 +-
 MainWindow.ProductionFatNoFlicker.cs          |   3 +-
 MainWindow.ProductionFatTab.cs                | 108 ++------
 MainWindow.SharedSclWorkspace.cs              |   5 +
 ...ductionFatEngineeringTabRegressionTests.cs |   2 +-
 ...uctionFatM2PermanentHostRegressionTests.cs |  78 ++++++
 tools/fat_m2_guard_fix.py                     |  10 -
 tools/fat_m2_permanent_host.py                | 252 ------------------
 12 files changed, 126 insertions(+), 445 deletions(-)
 delete mode 100644 .github/workflows/fat-m2-permanent-host-v2.yml
 delete mode 100644 .github/workflows/fat-m2-permanent-host.yml
 create mode 100644 tests/ARSAS.Tests/ProductionFatM2PermanentHostRegressionTests.cs
 delete mode 100644 tools/fat_m2_guard_fix.py
 delete mode 100644 tools/fat_m2_permanent_host.py

diff --git a/.github/workflows/fat-m2-permanent-host-v2.yml b/.github/workflows/fat-m2-permanent-host-v2.yml
deleted file mode 100644
index bc0f1d687..000000000
--- a/.github/workflows/fat-m2-permanent-host-v2.yml
+++ /dev/null
@@ -1,43 +0,0 @@
-name: FAT M2 permanent host migration v2
-
-on:
-  push:
-    branches:
-      - fix/fat-workstation-convergence
-    paths:
-      - .github/workflows/fat-m2-permanent-host-v2.yml
-      - tools/fat_m2_guard_fix.py
-
-permissions:
-  contents: write
-
-jobs:
-  migrate:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout staging branch
-        uses: actions/checkout@v4
-        with:
-          ref: fix/fat-workstation-convergence
-          fetch-depth: 0
-
-      - name: Correct guard and apply M2 migration
-        run: |
-          python tools/fat_m2_guard_fix.py
-          python tools/fat_m2_permanent_host.py
-
-      - name: Remove one-shot migration helpers
-        run: |
-          rm tools/fat_m2_guard_fix.py
-          rm tools/fat_m2_permanent_host.py
-          rm .github/workflows/fat-m2-permanent-host-v2.yml
-          rm .github/workflows/fat-m2-permanent-host.yml
-
-      - name: Commit M2 source changes
-        shell: bash
-        run: |
-          git config user.name "github-actions[bot]"
-          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
-          git add -A
-          git commit -m "feat: complete M2 permanent production FAT host"
-          git push origin HEAD:fix/fat-workstation-convergence
diff --git a/.github/workflows/fat-m2-permanent-host.yml b/.github/workflows/fat-m2-permanent-host.yml
deleted file mode 100644
index 1e05436ee..000000000
--- a/.github/workflows/fat-m2-permanent-host.yml
+++ /dev/null
@@ -1,43 +0,0 @@
-name: FAT M2 permanent host migration
-
-on:
-  push:
-    branches:
-      - fix/fat-workstation-convergence
-    paths:
-      - .github/workflows/fat-m2-permanent-host.yml
-      - tools/fat_m2_permanent_host.py
-
-permissions:
-  contents: write
-
-jobs:
-  migrate:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout staging branch
-        uses: actions/checkout@v4
-        with:
-          ref: fix/fat-workstation-convergence
-          fetch-depth: 0
-
-      - name: Apply guarded M2 migration
-        run: python tools/fat_m2_permanent_host.py
-
-      - name: Remove one-shot migration helpers
-        run: |
-          rm tools/fat_m2_permanent_host.py
-          rm .github/workflows/fat-m2-permanent-host.yml
-
-      - name: Commit M2 source changes
-        shell: bash
-        run: |
-          git config user.name "github-actions[bot]"
-          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
-          git add -A
-          if git diff --cached --quiet; then
-            echo "No migration changes to commit"
-            exit 0
-          fi
-          git commit -m "feat: complete M2 permanent production FAT host"
-          git push origin HEAD:fix/fat-workstation-convergence
diff --git a/IoListTestingWindow.EmbeddedEngineeringHost.cs b/IoListTestingWindow.EmbeddedEngineeringHost.cs
index 5e434facc..e8955f24a 100644
--- a/IoListTestingWindow.EmbeddedEngineeringHost.cs
+++ b/IoListTestingWindow.EmbeddedEngineeringHost.cs
@@ -28,6 +28,19 @@ internal static void RegisterEmbeddedEngineeringFatHost()
             handledEventsToo: true);
     }
 
+    internal void PrepareForEmbeddedEngineeringHost()
+    {
+        // Must run before Window.Show(). A transparent/off-screen, non-activating donor
+        // cannot produce the historical black/blank compositor frame while its exact
+        // production center is being re-parented into MainWindow.
+        ShowActivated = false;
+        ShowInTaskbar = false;
+        Opacity = 0d;
+        WindowStartupLocation = WindowStartupLocation.Manual;
+        Left = -32000d;
+        Top = -32000d;
+    }
+
     private static void EmbeddedEngineeringFatHost_Loaded(object sender, RoutedEventArgs e)
     {
         if (sender is not IoListTestingWindow window ||
@@ -45,9 +58,7 @@ window.Owner is not MainWindow owner ||
         // MainWindow's legacy launcher still calls Show() on this Window. Make that bootstrap
         // surface invisible immediately; the actual production visual is moved into Engineering
         // on the next Loaded-priority dispatcher turn, before ContextIdle command-panel work.
-        window.ShowActivated = false;
-        window.ShowInTaskbar = false;
-        window.Opacity = 0d;
+        window.PrepareForEmbeddedEngineeringHost();
 
         window.Dispatcher.BeginInvoke(
             DispatcherPriority.Loaded,
diff --git a/MainWindow.IoTesting.cs b/MainWindow.IoTesting.cs
index 52f1cfc91..69acfa89f 100644
--- a/MainWindow.IoTesting.cs
+++ b/MainWindow.IoTesting.cs
@@ -494,6 +494,8 @@ private Task ShowIoTestingWorkspaceAsync(IoTestWorkspaceLaunchResult launch, int
         var controller = launch.Session;
         var persistence = launch.Workspace;
         var window = new IoListTestingWindow(launch.Project, controller, persistence) { Owner = this };
+        if (ProductionFatTabReady)
+            window.PrepareForEmbeddedEngineeringHost();
         RegisterLoadedIoFatWindow(window);
         _activeIoTestSessionController = controller;
         Interlocked.Exchange(ref _ioTestObservationSequence, DateTime.UtcNow.Ticks);
@@ -525,7 +527,8 @@ void WindowClosed(object? sender, EventArgs args)
         }
 
         window.Closed += WindowClosed;
-        Hide();
+        if (!ProductionFatTabReady)
+            Hide();
         window.Show();
         return Task.CompletedTask;
     }
diff --git a/MainWindow.ProductionFatEngineeringBootstrap.cs b/MainWindow.ProductionFatEngineeringBootstrap.cs
index f7c8dfb36..bac287011 100644
--- a/MainWindow.ProductionFatEngineeringBootstrap.cs
+++ b/MainWindow.ProductionFatEngineeringBootstrap.cs
@@ -50,7 +50,7 @@ private void ProductionFatEngineeringBootstrap_SelectionChanged(object sender, S
 
     private void ProductionFatEngineeringBootstrap_PropertyChanged(object? sender, PropertyChangedEventArgs e)
     {
-        if (e.PropertyName != nameof(SelectedDevice) || MainTabs.SelectedIndex != NativeFatWorkspaceIndex)
+        if (e.PropertyName != nameof(SelectedDevice))
             return;
 
         // A running production FAT session owns its latched IED. The normal embedded-host
@@ -62,7 +62,7 @@ private void ProductionFatEngineeringBootstrap_PropertyChanged(object? sender, P
 
     private void QueueProductionFatEngineeringBootstrap()
     {
-        if (!_productionFatEngineeringBootstrapInstalled || MainTabs.SelectedIndex != NativeFatWorkspaceIndex)
+        if (!_productionFatEngineeringBootstrapInstalled)
             return;
 
         Dispatcher.BeginInvoke(
@@ -73,7 +73,6 @@ private void QueueProductionFatEngineeringBootstrap()
     private async Task EnsureProductionFatFromEngineeringAsync()
     {
         if (_productionFatEngineeringBootstrapBusy ||
-            MainTabs.SelectedIndex != NativeFatWorkspaceIndex ||
             !ProductionFatTabReady)
         {
             return;
diff --git a/MainWindow.ProductionFatNoFlicker.cs b/MainWindow.ProductionFatNoFlicker.cs
index e976ca883..f346e68f2 100644
--- a/MainWindow.ProductionFatNoFlicker.cs
+++ b/MainWindow.ProductionFatNoFlicker.cs
@@ -24,6 +24,5 @@ public partial class MainWindow
 
     private bool ShouldKeepEngineeringVisibleDuringProductionFatBootstrap()
         => _productionFatEngineeringBootstrapBusy &&
-           ProductionFatTabReady &&
-           MainTabs.SelectedIndex == NativeFatWorkspaceIndex;
+           ProductionFatTabReady;
 }
diff --git a/MainWindow.ProductionFatTab.cs b/MainWindow.ProductionFatTab.cs
index 33a9f3c46..4a8e0f0a0 100644
--- a/MainWindow.ProductionFatTab.cs
+++ b/MainWindow.ProductionFatTab.cs
@@ -72,7 +72,12 @@ private void TryInstallProductionFatTabPivot()
         PropertyChanged -= NativeFat_MainWindowPropertyChanged;
         MainTabs.SelectionChanged -= NativeFat_MainTabsSelectionChanged;
 
-        _nativeFatTab.Content = BuildProductionFatLauncher();
+        _nativeFatTab.Content = BuildProductionFatPermanentHost();
+
+        // M2 prewarm starts as soon as the canonical host exists. It is deliberately
+        // independent of the currently selected tab so a valid Engineering SCL/DataSet
+        // can prepare the exact production surface before the operator first opens FAT.
+        QueueProductionFatEngineeringBootstrap();
 
         // MainWindow.xaml owns the FAT button's SegmentedNavButton style and NavButton_Click.
         // Production FAT reacts to tab selection below; it must not install a second click owner.
@@ -91,85 +96,21 @@ private void ProductionFatInstallRetry_Tick(object? sender, EventArgs e)
         TryInstallProductionFatTabPivot();
     }
 
-    private FrameworkElement BuildProductionFatLauncher()
+    private FrameworkElement BuildProductionFatPermanentHost()
     {
+        // This is a stable shell slot, not a launcher/form. With a valid Engineering
+        // static DataSet it is replaced in the background by the exact production FAT
+        // workspace before first navigation. With no eligible IED it remains a quiet
+        // contextual empty state and never creates an alternate FAT workflow.
         var root = new Grid { Margin = new Thickness(0) };
-        var card = new Border
+        root.Children.Add(new TextBlock
         {
-            MaxWidth = 720,
-            Padding = new Thickness(28, 24, 28, 24),
-            CornerRadius = new CornerRadius(16),
-            Background = TryFindResource("Surface") as Brush ?? Brushes.White,
-            BorderBrush = TryFindResource("Line") as Brush ?? new SolidColorBrush(Color.FromRgb(0xDC, 0xE4, 0xEF)),
-            BorderThickness = new Thickness(1),
+            Text = "FAT · awaiting an Engineering IED with static DataSet scope",
+            FontSize = 12,
+            Foreground = TryFindResource("Muted") as Brush ?? Brushes.DimGray,
             HorizontalAlignment = HorizontalAlignment.Center,
             VerticalAlignment = VerticalAlignment.Center
-        };
-
-        var content = new StackPanel();
-        content.Children.Add(new TextBlock
-        {
-            Text = "FAT WORKSPACE",
-            Style = TryFindResource("MicroLabel") as Style,
-            Foreground = TryFindResource("Accent") as Brush,
-            HorizontalAlignment = HorizontalAlignment.Center
-        });
-        content.Children.Add(new TextBlock
-        {
-            Text = "Production FAT inside Engineering",
-            Margin = new Thickness(0, 7, 0, 0),
-            FontSize = 22,
-            FontWeight = FontWeights.SemiBold,
-            Foreground = TryFindResource("Ink") as Brush ?? Brushes.Black,
-            HorizontalAlignment = HorizontalAlignment.Center
-        });
-        content.Children.Add(new TextBlock
-        {
-            Text = "Open an SCL FAT project to use the proven automatic capture / completion workflow. The global IED Explorer stays visible at left and the shared Command Dock remains the only command surface.",
-            Margin = new Thickness(0, 10, 0, 18),
-            MaxWidth = 610,
-            TextAlignment = TextAlignment.Center,
-            TextWrapping = TextWrapping.Wrap,
-            FontSize = 12.2,
-            Foreground = TryFindResource("Muted") as Brush ?? Brushes.DimGray
-        });
-
-        var actions = new StackPanel
-        {
-            Orientation = Orientation.Horizontal,
-            HorizontalAlignment = HorizontalAlignment.Center
-        };
-        var openScl = new Button
-        {
-            Content = "Open SCL for FAT",
-            Style = TryFindResource("PrimaryButton") as Style,
-            Padding = new Thickness(14, 8, 14, 8),
-            Margin = new Thickness(0, 0, 8, 0)
-        };
-        openScl.Click += OpenSclFatTesting_Click;
-        actions.Children.Add(openScl);
-
-        var openProject = new Button
-        {
-            Content = "Open ARSAS Project",
-            Style = TryFindResource("SoftButton") as Style,
-            Padding = new Thickness(14, 8, 14, 8)
-        };
-        openProject.Click += OpenIoListPackage_Click;
-        actions.Children.Add(openProject);
-        content.Children.Add(actions);
-
-        content.Children.Add(new TextBlock
-        {
-            Text = "Excel workflow is intentionally not part of this primary FAT tab.",
-            Margin = new Thickness(0, 14, 0, 0),
-            FontSize = 10.6,
-            Foreground = TryFindResource("Muted") as Brush ?? Brushes.DimGray,
-            HorizontalAlignment = HorizontalAlignment.Center
         });
-
-        card.Child = content;
-        root.Children.Add(card);
         return root;
     }
 
@@ -217,20 +158,13 @@ internal bool MountProductionFatWorkspace(IoListTestingWindow window, FrameworkE
         window.Closed += ProductionFatWindow_Closed;
         SynchronizeProductionFatSelectedIed();
 
-        MainTabs.SelectedIndex = NativeFatWorkspaceIndex;
+        // Passive mount: prewarming must never navigate, hide/show, activate, or steal
+        // focus from the operator's current Engineering destination.
+        window.RegisterEmbeddedHostCloseCleanup();
         QueueNativeFatNavigationGeometry();
 
-        // The legacy launcher hides Engineering before showing IoListTestingWindow.
-        // Once its proven central workspace is re-parented here, restore Engineering and
-        // keep the legacy Window loaded-but-hidden solely as the production controller owner.
-        IsEnabled = true;
-        if (!IsVisible)
-            Show();
-        if (WindowState == WindowState.Minimized)
-            WindowState = WindowState.Normal;
-        Activate();
-
-        SetStatus($"FAT ready in Engineering tab · {window.Project.Ieds.Count} IED · production auto-capture workflow.");
+        if (MainTabs.SelectedIndex == NativeFatWorkspaceIndex)
+            SetStatus($"FAT ready in Engineering tab · {window.Project.Ieds.Count} IED · production auto-capture workflow.");
         return true;
     }
 
@@ -243,7 +177,7 @@ internal void UnmountProductionFatWorkspace(IoListTestingWindow window)
         _productionFatWindow = null;
         _productionFatSurface = null;
         if (_nativeFatTab != null)
-            _nativeFatTab.Content = BuildProductionFatLauncher();
+            _nativeFatTab.Content = BuildProductionFatPermanentHost();
     }
 
     private void ProductionFatWindow_Closed(object? sender, EventArgs e)
diff --git a/MainWindow.SharedSclWorkspace.cs b/MainWindow.SharedSclWorkspace.cs
index a7a0ef71b..1fcf55dd0 100644
--- a/MainWindow.SharedSclWorkspace.cs
+++ b/MainWindow.SharedSclWorkspace.cs
@@ -98,6 +98,11 @@ private void ApplyStaticDataSetSelection(Iec61850MonitorDevice device)
         // shared monitor to start and never changes acquisition method.
         LogStaticDataSetReportFeasibility(device);
         _ = ObserveInitialStaticReportEvidenceAsync(device);
+
+        // M2 permanent FAT host: authority establishment is also a readiness trigger.
+        // This covers SCL refresh on the same SelectedDevice, where PropertyChanged for
+        // SelectedDevice would otherwise not fire.
+        QueueProductionFatEngineeringBootstrap();
     }
 
     private void ClearSharedSignalSelection(Iec61850MonitorDevice device)
diff --git a/tests/ARSAS.Tests/ProductionFatEngineeringTabRegressionTests.cs b/tests/ARSAS.Tests/ProductionFatEngineeringTabRegressionTests.cs
index 9da4dd527..91cc08816 100644
--- a/tests/ARSAS.Tests/ProductionFatEngineeringTabRegressionTests.cs
+++ b/tests/ARSAS.Tests/ProductionFatEngineeringTabRegressionTests.cs
@@ -21,7 +21,7 @@ public void ProductionFatTab_AutoBootstrapsFromSelectedEngineeringStaticDataSet(
     {
         var source = File.ReadAllText(FindRepoFile("MainWindow.ProductionFatEngineeringBootstrap.cs"));
 
-        Assert.Contains("MainTabs.SelectedIndex != NativeFatWorkspaceIndex", source, StringComparison.Ordinal);
+        Assert.Contains("QueueProductionFatEngineeringBootstrap();", source, StringComparison.Ordinal);
         Assert.Contains("selected?.SclWorkspace", source, StringComparison.Ordinal);
         Assert.Contains("DesignModel.DataSets.Sum", source, StringComparison.Ordinal);
         Assert.Contains("IoFatEngineeringWorkspaceProjectionService.BuildAsync", source, StringComparison.Ordinal);
diff --git a/tests/ARSAS.Tests/ProductionFatM2PermanentHostRegressionTests.cs b/tests/ARSAS.Tests/ProductionFatM2PermanentHostRegressionTests.cs
new file mode 100644
index 000000000..eb01af699
--- /dev/null
+++ b/tests/ARSAS.Tests/ProductionFatM2PermanentHostRegressionTests.cs
@@ -0,0 +1,78 @@
+namespace ARSAS.Tests;
+
+public sealed class ProductionFatM2PermanentHostRegressionTests
+{
+    [Fact]
+    public void FatTab_IsPermanentHost_NotLauncherOrAlternateOpenSclWorkflow()
+    {
+        var source = Read("MainWindow.ProductionFatTab.cs");
+
+        Assert.Contains("BuildProductionFatPermanentHost()", source, StringComparison.Ordinal);
+        Assert.DoesNotContain("BuildProductionFatLauncher", source, StringComparison.Ordinal);
+        Assert.DoesNotContain("Open SCL for FAT", source, StringComparison.Ordinal);
+        Assert.DoesNotContain("Open ARSAS Project", source, StringComparison.Ordinal);
+        Assert.DoesNotContain("OpenSclFatTesting_Click", source, StringComparison.Ordinal);
+        Assert.DoesNotContain("OpenIoListPackage_Click", source, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void EngineeringStaticDataSet_PrewarmIsIndependentOfFatTabSelection()
+    {
+        var bootstrap = Read("MainWindow.ProductionFatEngineeringBootstrap.cs");
+        var shared = Read("MainWindow.SharedSclWorkspace.cs");
+
+        Assert.Contains("e.PropertyName != nameof(SelectedDevice)", bootstrap, StringComparison.Ordinal);
+        Assert.Contains("QueueProductionFatEngineeringBootstrap();", shared, StringComparison.Ordinal);
+        Assert.DoesNotContain("_productionFatEngineeringBootstrapBusy ||\n            MainTabs.SelectedIndex != NativeFatWorkspaceIndex", bootstrap, StringComparison.Ordinal);
+        Assert.DoesNotContain("_productionFatEngineeringBootstrapInstalled || MainTabs.SelectedIndex != NativeFatWorkspaceIndex", bootstrap, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void EmbeddedDonor_IsPreparedBeforeShow_AndMainWindowStaysVisible()
+    {
+        var launch = Read("MainWindow.IoTesting.cs");
+        var host = Read("IoListTestingWindow.EmbeddedEngineeringHost.cs");
+        var tab = Read("MainWindow.ProductionFatTab.cs");
+
+        var prepare = launch.IndexOf("window.PrepareForEmbeddedEngineeringHost();", StringComparison.Ordinal);
+        var show = launch.IndexOf("window.Show();", StringComparison.Ordinal);
+        Assert.True(prepare >= 0 && show > prepare, "Donor visibility must be prepared before Window.Show().");
+        Assert.Contains("if (!ProductionFatTabReady)\n            Hide();", launch, StringComparison.Ordinal);
+        Assert.Contains("Left = -32000d", host, StringComparison.Ordinal);
+        Assert.Contains("Opacity = 0d", host, StringComparison.Ordinal);
+        Assert.Contains("ShowActivated = false", host, StringComparison.Ordinal);
+        Assert.Contains("ShowInTaskbar = false", host, StringComparison.Ordinal);
+
+        Assert.DoesNotContain("MainTabs.SelectedIndex = NativeFatWorkspaceIndex", tab, StringComparison.Ordinal);
+        Assert.DoesNotContain("Activate();", tab, StringComparison.Ordinal);
+        Assert.DoesNotContain("if (!IsVisible)\n            Show();", tab, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void EmbeddedSurface_RemainsExactProductionGridAndPreviewSource()
+    {
+        var host = Read("IoListTestingWindow.EmbeddedEngineeringHost.cs");
+
+        Assert.Contains("InstallFatV2WorkspaceUx();", host, StringComparison.Ordinal);
+        Assert.Contains("InstallPerIedPrintPreview();", host, StringComparison.Ordinal);
+        Assert.Contains("DetachProductionFatCentralWorkspace()", host, StringComparison.Ordinal);
+        Assert.Contains("owner.MountProductionFatWorkspace(this, surface)", host, StringComparison.Ordinal);
+    }
+
+    private static string Read(string relativePath)
+        => File.ReadAllText(Path.Combine(FindRepoRoot(), relativePath));
+
+    private static string FindRepoRoot()
+    {
+        DirectoryInfo? directory = new(AppContext.BaseDirectory);
+        while (directory != null)
+        {
+            if (File.Exists(Path.Combine(directory.FullName, "MainWindow.xaml")) &&
+                Directory.Exists(Path.Combine(directory.FullName, "tests", "ARSAS.Tests")))
+                return directory.FullName;
+            directory = directory.Parent;
+        }
+
+        throw new DirectoryNotFoundException("Could not locate repository root.");
+    }
+}
diff --git a/tools/fat_m2_guard_fix.py b/tools/fat_m2_guard_fix.py
deleted file mode 100644
index 1b0a8c76c..000000000
--- a/tools/fat_m2_guard_fix.py
+++ /dev/null
@@ -1,10 +0,0 @@
-from pathlib import Path
-
-path = Path(__file__).with_name("fat_m2_permanent_host.py")
-source = path.read_text(encoding="utf-8")
-old = '''s = replace_once(\n    s,\n    "        _nativeFatTab.Content = BuildProductionFatLauncher();",\n    "        _nativeFatTab.Content = BuildProductionFatPermanentHost();\\n\\n        // M2 prewarm starts as soon as the canonical host exists. It is deliberately\\n        // independent of the currently selected tab so a valid Engineering SCL/DataSet\\n        // can prepare the exact production surface before the operator first opens FAT.\\n        QueueProductionFatEngineeringBootstrap();",\n    "install permanent FAT host")'''
-new = '''install_launcher = "        _nativeFatTab.Content = BuildProductionFatLauncher();"\nif s.count(install_launcher) != 2:\n    raise SystemExit(f"install permanent FAT host: expected install + unmount matches, found {s.count(install_launcher)}")\ns = s.replace(\n    install_launcher,\n    "        _nativeFatTab.Content = BuildProductionFatPermanentHost();\\n\\n        // M2 prewarm starts as soon as the canonical host exists. It is deliberately\\n        // independent of the currently selected tab so a valid Engineering SCL/DataSet\\n        // can prepare the exact production surface before the operator first opens FAT.\\n        QueueProductionFatEngineeringBootstrap();",\n    1)'''
-if source.count(old) != 1:
-    raise SystemExit(f"guard fixer expected one original install block, found {source.count(old)}")
-path.write_text(source.replace(old, new, 1), encoding="utf-8")
-print("M2 guard corrected: launcher install/unmount pair distinguished")
diff --git a/tools/fat_m2_permanent_host.py b/tools/fat_m2_permanent_host.py
deleted file mode 100644
index a35256f1a..000000000
--- a/tools/fat_m2_permanent_host.py
+++ /dev/null
@@ -1,252 +0,0 @@
-from pathlib import Path
-import re
-
-ROOT = Path(__file__).resolve().parents[1]
-
-
-def read(path):
-    return (ROOT / path).read_text(encoding="utf-8")
-
-
-def write(path, text):
-    (ROOT / path).write_text(text, encoding="utf-8")
-
-
-def replace_once(text, old, new, label):
-    count = text.count(old)
-    if count != 1:
-        raise SystemExit(f"{label}: expected exactly 1 match, found {count}")
-    return text.replace(old, new, 1)
-
-
-# M2.1 - FAT is a permanent MainWindow host, never a launcher workflow.
-path = "MainWindow.ProductionFatTab.cs"
-s = read(path)
-s = replace_once(
-    s,
-    "        _nativeFatTab.Content = BuildProductionFatLauncher();",
-    "        _nativeFatTab.Content = BuildProductionFatPermanentHost();\n\n        // M2 prewarm starts as soon as the canonical host exists. It is deliberately\n        // independent of the currently selected tab so a valid Engineering SCL/DataSet\n        // can prepare the exact production surface before the operator first opens FAT.\n        QueueProductionFatEngineeringBootstrap();",
-    "install permanent FAT host")
-
-pattern = re.compile(
-    r"    private FrameworkElement BuildProductionFatLauncher\(\)\n    \{.*?\n    \}\n\n    private void ProductionFat_MainTabsSelectionChanged",
-    re.S,
-)
-replacement = '''    private FrameworkElement BuildProductionFatPermanentHost()
-    {
-        // This is a stable shell slot, not a launcher/form. With a valid Engineering
-        // static DataSet it is replaced in the background by the exact production FAT
-        // workspace before first navigation. With no eligible IED it remains a quiet
-        // contextual empty state and never creates an alternate FAT workflow.
-        var root = new Grid { Margin = new Thickness(0) };
-        root.Children.Add(new TextBlock
-        {
-            Text = "FAT · awaiting an Engineering IED with static DataSet scope",
-            FontSize = 12,
-            Foreground = TryFindResource("Muted") as Brush ?? Brushes.DimGray,
-            HorizontalAlignment = HorizontalAlignment.Center,
-            VerticalAlignment = VerticalAlignment.Center
-        });
-        return root;
-    }
-
-    private void ProductionFat_MainTabsSelectionChanged'''
-s, n = pattern.subn(replacement, s, count=1)
-if n != 1:
-    raise SystemExit(f"replace production launcher body: expected 1 match, found {n}")
-
-s = replace_once(
-    s,
-    "        MainTabs.SelectedIndex = NativeFatWorkspaceIndex;\n        QueueNativeFatNavigationGeometry();\n\n        // The legacy launcher hides Engineering before showing IoListTestingWindow.\n        // Once its proven central workspace is re-parented here, restore Engineering and\n        // keep the legacy Window loaded-but-hidden solely as the production controller owner.\n        IsEnabled = true;\n        if (!IsVisible)\n            Show();\n        if (WindowState == WindowState.Minimized)\n            WindowState = WindowState.Normal;\n        Activate();\n\n        SetStatus($\"FAT ready in Engineering tab · {window.Project.Ieds.Count} IED · production auto-capture workflow.\");",
-    "        // Passive mount: prewarming must never navigate, hide/show, activate, or steal\n        // focus from the operator's current Engineering destination.\n        window.RegisterEmbeddedHostCloseCleanup();\n        QueueNativeFatNavigationGeometry();\n\n        if (MainTabs.SelectedIndex == NativeFatWorkspaceIndex)\n            SetStatus($\"FAT ready in Engineering tab · {window.Project.Ieds.Count} IED · production auto-capture workflow.\");",
-    "passive production FAT mount")
-
-s = replace_once(
-    s,
-    "            _nativeFatTab.Content = BuildProductionFatLauncher();",
-    "            _nativeFatTab.Content = BuildProductionFatPermanentHost();",
-    "unmount permanent FAT host")
-write(path, s)
-
-
-# M2.2 - Bootstrap is prewarm, not post-navigation work.
-path = "MainWindow.ProductionFatEngineeringBootstrap.cs"
-s = read(path)
-s = replace_once(
-    s,
-    "        if (e.PropertyName != nameof(SelectedDevice) || MainTabs.SelectedIndex != NativeFatWorkspaceIndex)\n            return;",
-    "        if (e.PropertyName != nameof(SelectedDevice))\n            return;",
-    "selected-device prewarm gate")
-s = replace_once(
-    s,
-    "        if (!_productionFatEngineeringBootstrapInstalled || MainTabs.SelectedIndex != NativeFatWorkspaceIndex)\n            return;",
-    "        if (!_productionFatEngineeringBootstrapInstalled)\n            return;",
-    "queue prewarm gate")
-s = replace_once(
-    s,
-    "        if (_productionFatEngineeringBootstrapBusy ||\n            MainTabs.SelectedIndex != NativeFatWorkspaceIndex ||\n            !ProductionFatTabReady)",
-    "        if (_productionFatEngineeringBootstrapBusy ||\n            !ProductionFatTabReady)",
-    "ensure prewarm gate")
-write(path, s)
-
-
-# M2.3 - Establish static DataSet authority as an explicit prewarm trigger too. This
-# covers same-IED SCL refreshes where SelectedDevice itself does not change.
-path = "MainWindow.SharedSclWorkspace.cs"
-s = read(path)
-s = replace_once(
-    s,
-    "        _ = ObserveInitialStaticReportEvidenceAsync(device);",
-    "        _ = ObserveInitialStaticReportEvidenceAsync(device);\n\n        // M2 permanent FAT host: authority establishment is also a readiness trigger.\n        // This covers SCL refresh on the same SelectedDevice, where PropertyChanged for\n        // SelectedDevice would otherwise not fire.\n        QueueProductionFatEngineeringBootstrap();",
-    "static DataSet prewarm trigger")
-write(path, s)
-
-
-# M2.4 - Prepare the donor window before Show(), not from Loaded after first paint.
-path = "IoListTestingWindow.EmbeddedEngineeringHost.cs"
-s = read(path)
-anchor = "    private static void EmbeddedEngineeringFatHost_Loaded(object sender, RoutedEventArgs e)\n"
-method = '''    internal void PrepareForEmbeddedEngineeringHost()
-    {
-        // Must run before Window.Show(). A transparent/off-screen, non-activating donor
-        // cannot produce the historical black/blank compositor frame while its exact
-        // production center is being re-parented into MainWindow.
-        ShowActivated = false;
-        ShowInTaskbar = false;
-        Opacity = 0d;
-        WindowStartupLocation = WindowStartupLocation.Manual;
-        Left = -32000d;
-        Top = -32000d;
-    }
-
-'''
-if method.strip() not in s:
-    s = replace_once(s, anchor, method + anchor, "insert pre-show donor preparation")
-s = replace_once(
-    s,
-    "        window.ShowActivated = false;\n        window.ShowInTaskbar = false;\n        window.Opacity = 0d;",
-    "        window.PrepareForEmbeddedEngineeringHost();",
-    "reuse donor preparation")
-write(path, s)
-
-
-# M2.5 - The production launch path prepares donor visibility before Show and does not
-# hide MainWindow when the canonical embedded host exists.
-path = "MainWindow.IoTesting.cs"
-s = read(path)
-s = replace_once(
-    s,
-    "        var window = new IoListTestingWindow(launch.Project, controller, persistence) { Owner = this };\n        RegisterLoadedIoFatWindow(window);",
-    "        var window = new IoListTestingWindow(launch.Project, controller, persistence) { Owner = this };\n        if (ProductionFatTabReady)\n            window.PrepareForEmbeddedEngineeringHost();\n        RegisterLoadedIoFatWindow(window);",
-    "prepare donor before Show")
-s = replace_once(
-    s,
-    "        window.Closed += WindowClosed;\n        Hide();\n        window.Show();",
-    "        window.Closed += WindowClosed;\n        if (!ProductionFatTabReady)\n            Hide();\n        window.Show();",
-    "keep Engineering visible")
-write(path, s)
-
-
-# M2.6 - Keep old shadow-Hide safety net correct while it remains until M7 cleanup.
-path = "MainWindow.ProductionFatNoFlicker.cs"
-s = read(path)
-s = replace_once(
-    s,
-    "        => _productionFatEngineeringBootstrapBusy &&\n           ProductionFatTabReady &&\n           MainTabs.SelectedIndex == NativeFatWorkspaceIndex;",
-    "        => _productionFatEngineeringBootstrapBusy &&\n           ProductionFatTabReady;",
-    "background prewarm no-flicker guard")
-write(path, s)
-
-
-# M2.7 - Update the existing architecture regression and add a focused permanent-host gate.
-path = "tests/ARSAS.Tests/ProductionFatEngineeringTabRegressionTests.cs"
-s = read(path)
-s = replace_once(
-    s,
-    "        Assert.Contains(\"MainTabs.SelectedIndex != NativeFatWorkspaceIndex\", source, StringComparison.Ordinal);",
-    "        Assert.Contains(\"QueueProductionFatEngineeringBootstrap();\", source, StringComparison.Ordinal);",
-    "update bootstrap regression")
-write(path, s)
-
-new_test = ROOT / "tests/ARSAS.Tests/ProductionFatM2PermanentHostRegressionTests.cs"
-new_test.write_text(r'''namespace ARSAS.Tests;
-
-public sealed class ProductionFatM2PermanentHostRegressionTests
-{
-    [Fact]
-    public void FatTab_IsPermanentHost_NotLauncherOrAlternateOpenSclWorkflow()
-    {
-        var source = Read("MainWindow.ProductionFatTab.cs");
-
-        Assert.Contains("BuildProductionFatPermanentHost()", source, StringComparison.Ordinal);
-        Assert.DoesNotContain("BuildProductionFatLauncher", source, StringComparison.Ordinal);
-        Assert.DoesNotContain("Open SCL for FAT", source, StringComparison.Ordinal);
-        Assert.DoesNotContain("Open ARSAS Project", source, StringComparison.Ordinal);
-        Assert.DoesNotContain("OpenSclFatTesting_Click", source, StringComparison.Ordinal);
-        Assert.DoesNotContain("OpenIoListPackage_Click", source, StringComparison.Ordinal);
-    }
-
-    [Fact]
-    public void EngineeringStaticDataSet_PrewarmIsIndependentOfFatTabSelection()
-    {
-        var bootstrap = Read("MainWindow.ProductionFatEngineeringBootstrap.cs");
-        var shared = Read("MainWindow.SharedSclWorkspace.cs");
-
-        Assert.Contains("e.PropertyName != nameof(SelectedDevice)", bootstrap, StringComparison.Ordinal);
-        Assert.Contains("QueueProductionFatEngineeringBootstrap();", shared, StringComparison.Ordinal);
-        Assert.DoesNotContain("_productionFatEngineeringBootstrapBusy ||\n            MainTabs.SelectedIndex != NativeFatWorkspaceIndex", bootstrap, StringComparison.Ordinal);
-        Assert.DoesNotContain("_productionFatEngineeringBootstrapInstalled || MainTabs.SelectedIndex != NativeFatWorkspaceIndex", bootstrap, StringComparison.Ordinal);
-    }
-
-    [Fact]
-    public void EmbeddedDonor_IsPreparedBeforeShow_AndMainWindowStaysVisible()
-    {
-        var launch = Read("MainWindow.IoTesting.cs");
-        var host = Read("IoListTestingWindow.EmbeddedEngineeringHost.cs");
-        var tab = Read("MainWindow.ProductionFatTab.cs");
-
-        var prepare = launch.IndexOf("window.PrepareForEmbeddedEngineeringHost();", StringComparison.Ordinal);
-        var show = launch.IndexOf("window.Show();", StringComparison.Ordinal);
-        Assert.True(prepare >= 0 && show > prepare, "Donor visibility must be prepared before Window.Show().");
-        Assert.Contains("if (!ProductionFatTabReady)\n            Hide();", launch, StringComparison.Ordinal);
-        Assert.Contains("Left = -32000d", host, StringComparison.Ordinal);
-        Assert.Contains("Opacity = 0d", host, StringComparison.Ordinal);
-        Assert.Contains("ShowActivated = false", host, StringComparison.Ordinal);
-        Assert.Contains("ShowInTaskbar = false", host, StringComparison.Ordinal);
-
-        Assert.DoesNotContain("MainTabs.SelectedIndex = NativeFatWorkspaceIndex", tab, StringComparison.Ordinal);
-        Assert.DoesNotContain("Activate();", tab, StringComparison.Ordinal);
-        Assert.DoesNotContain("if (!IsVisible)\n            Show();", tab, StringComparison.Ordinal);
-    }
-
-    [Fact]
-    public void EmbeddedSurface_RemainsExactProductionGridAndPreviewSource()
-    {
-        var host = Read("IoListTestingWindow.EmbeddedEngineeringHost.cs");
-
-        Assert.Contains("InstallFatV2WorkspaceUx();", host, StringComparison.Ordinal);
-        Assert.Contains("InstallPerIedPrintPreview();", host, StringComparison.Ordinal);
-        Assert.Contains("DetachProductionFatCentralWorkspace()", host, StringComparison.Ordinal);
-        Assert.Contains("owner.MountProductionFatWorkspace(this, surface)", host, StringComparison.Ordinal);
-    }
-
-    private static string Read(string relativePath)
-        => File.ReadAllText(Path.Combine(FindRepoRoot(), relativePath));
-
-    private static string FindRepoRoot()
-    {
-        DirectoryInfo? directory = new(AppContext.BaseDirectory);
-        while (directory != null)
-        {
-            if (File.Exists(Path.Combine(directory.FullName, "MainWindow.xaml")) &&
-                Directory.Exists(Path.Combine(directory.FullName, "tests", "ARSAS.Tests")))
-                return directory.FullName;
-            directory = directory.Parent;
-        }
-
-        throw new DirectoryNotFoundException("Could not locate repository root.");
-    }
-}
-''', encoding="utf-8")
-
-print("M2 permanent FAT host migration applied successfully")

From 581e3b40182a8af37d29c9212b7c5703c840fb8f Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 09:06:36 +0700
Subject: [PATCH 20/84] docs: record M2 permanent FAT host verification
 contract

---
 docs/FAT_M2_PERMANENT_HOST_VERIFICATION.md | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
 create mode 100644 docs/FAT_M2_PERMANENT_HOST_VERIFICATION.md

diff --git a/docs/FAT_M2_PERMANENT_HOST_VERIFICATION.md b/docs/FAT_M2_PERMANENT_HOST_VERIFICATION.md
new file mode 100644
index 000000000..9cd780163
--- /dev/null
+++ b/docs/FAT_M2_PERMANENT_HOST_VERIFICATION.md
@@ -0,0 +1,18 @@
+# FAT M2 — Permanent Production Host Verification
+
+M2 removes the FAT launcher as the primary Engineering experience and keeps the proven production FAT surface as the single presentation/engine authority.
+
+## Code contract
+
+- `MainWindow` owns the canonical FAT tab and permanent host slot.
+- Engineering static DataSet authority may prewarm FAT before the operator navigates to FAT.
+- Prewarm does not change `MainTabs.SelectedIndex`, call `MainWindow.Show()`, call `Activate()`, or steal focus.
+- `IoListTestingWindow` remains a temporary compatibility donor/controller owner only; it is prepared transparent, off-screen, non-activating, and absent from the taskbar before `Window.Show()`.
+- `MainWindow` remains visible while the embedded donor is initialized.
+- The embedded center is the exact production workspace detached from `IoListTestingWindow`; `InstallFatV2WorkspaceUx()` and the existing report-preview installer remain the presentation sources.
+- No `Open SCL for FAT` or `Open ARSAS Project` launcher is exposed in the canonical FAT tab.
+- Engineering continues to supply the already parsed SCL/static DataSet and shared live runtime; M2 does not introduce a second parser or acquisition authority.
+
+## Verification gate
+
+M2 is **code complete** only when the permanent-host regression tests compile and pass. It is **CI verified** only when the staging head passes the repository Build ARSAS, IO List Testing, and SV evidence validation workflows. Physical no-flicker behavior remains a field-verification item and must not be claimed from CI alone.

From cc0f855676904bb8d80ed32578f7fef5ce6d4042 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 09:12:12 +0700
Subject: [PATCH 21/84] test: make M2 permanent-host regression line-ending
 stable

---
 .../ARSAS.Tests/ProductionFatM2PermanentHostRegressionTests.cs  | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/ARSAS.Tests/ProductionFatM2PermanentHostRegressionTests.cs b/tests/ARSAS.Tests/ProductionFatM2PermanentHostRegressionTests.cs
index eb01af699..75266cc0d 100644
--- a/tests/ARSAS.Tests/ProductionFatM2PermanentHostRegressionTests.cs
+++ b/tests/ARSAS.Tests/ProductionFatM2PermanentHostRegressionTests.cs
@@ -60,7 +60,7 @@ public void EmbeddedSurface_RemainsExactProductionGridAndPreviewSource()
     }
 
     private static string Read(string relativePath)
-        => File.ReadAllText(Path.Combine(FindRepoRoot(), relativePath));
+        => File.ReadAllText(Path.Combine(FindRepoRoot(), relativePath)).Replace("\r\n", "\n", StringComparison.Ordinal);
 
     private static string FindRepoRoot()
     {

From 2f82570e4810869ddb41870bf662d02081f6e79f Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 09:12:34 +0700
Subject: [PATCH 22/84] test: align P0 no-flicker contract with M2 background
 prewarm

---
 tests/ARSAS.Tests/ProductionFatP0FieldRegressionTests.cs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/ARSAS.Tests/ProductionFatP0FieldRegressionTests.cs b/tests/ARSAS.Tests/ProductionFatP0FieldRegressionTests.cs
index 2a220125e..6b6beeff0 100644
--- a/tests/ARSAS.Tests/ProductionFatP0FieldRegressionTests.cs
+++ b/tests/ARSAS.Tests/ProductionFatP0FieldRegressionTests.cs
@@ -78,7 +78,7 @@ public void EmbeddedAutomaticBootstrap_NeverHidesEngineeringWindow()
         Assert.Contains("ShouldKeepEngineeringVisibleDuringProductionFatBootstrap", source, StringComparison.Ordinal);
         Assert.Contains("_productionFatEngineeringBootstrapBusy", source, StringComparison.Ordinal);
         Assert.Contains("ProductionFatTabReady", source, StringComparison.Ordinal);
-        Assert.Contains("MainTabs.SelectedIndex == NativeFatWorkspaceIndex", source, StringComparison.Ordinal);
+        Assert.DoesNotContain("MainTabs.SelectedIndex == NativeFatWorkspaceIndex", source, StringComparison.Ordinal);
         Assert.Contains("base.Hide();", source, StringComparison.Ordinal);
     }
 

From 6f67d923114b1ac6c3f3730364e4691ac16b6358 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 09:17:08 +0700
Subject: [PATCH 23/84] chore: stage guarded M3 capture target latch migration

---
 tools/fat_m3_latch_capture_target.py | 54 ++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)
 create mode 100644 tools/fat_m3_latch_capture_target.py

diff --git a/tools/fat_m3_latch_capture_target.py b/tools/fat_m3_latch_capture_target.py
new file mode 100644
index 000000000..68d63c899
--- /dev/null
+++ b/tools/fat_m3_latch_capture_target.py
@@ -0,0 +1,54 @@
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[1]
+
+
+def read(path):
+    return (ROOT / path).read_text(encoding="utf-8")
+
+
+def write(path, text):
+    (ROOT / path).write_text(text, encoding="utf-8")
+
+
+def replace_once(text, old, new, label):
+    count = text.count(old)
+    if count != 1:
+        raise SystemExit(f"{label}: expected exactly 1 match, found {count}")
+    return text.replace(old, new, 1)
+
+
+# M3.1 - Start is a capture-target operation, never a viewed-context operation.
+path = "Services/IoTesting/IoTestMultiSessionCoordinator.cs"
+s = read(path)
+s = replace_once(
+    s,
+    "        SelectContext(ied);\n        IoTestSessionController controller;",
+    "        // M3: the caller latches the capture target before any asynchronous IED\n        // preparation. Starting that target must never steal the Explorer/view context\n        // if the operator selected another IED while preparation was in flight.\n        IoTestSessionController controller;",
+    "separate capture Start from viewed SelectContext")
+write(path, s)
+
+
+# M3.2 - Make the embedded Engineering binding contract explicit. SelectedIed is the
+# viewed context; per-IED session controllers remain evidence/capture authority.
+path = "IoListTestingWindow.EmbeddedEngineeringHost.cs"
+s = read(path)
+s = replace_once(
+    s,
+    "        // Do not retarget an active production FAT transaction/session. When idle, the\n        // persistent Engineering IED Explorer is the navigation/selection authority.\n        if (!CanSelectIed)\n            return;",
+    "        // M3 viewed-device contract: the persistent Engineering IED Explorer owns\n        // what the FAT grid displays. SelectedIed/Session.SelectContext changes only that\n        // projection; an active capture remains latched inside its per-IED controller.\n        if (!CanSelectIed)\n            return;",
+    "document viewed-device binding")
+write(path, s)
+
+
+# M3.3 - Document the async latch at the exact point where it is established.
+path = "IoListTestingWindow.xaml.cs"
+s = read(path)
+s = replace_once(
+    s,
+    "        var selectedIed = SelectedIed;\n        if (selectedIed?.IsPreparing == true)",
+    "        // Capture target latch: keep this local IED for the complete async prepare +\n        // Start transaction even if the global Engineering Explorer changes selection.\n        var selectedIed = SelectedIed;\n        if (selectedIed?.IsPreparing == true)",
+    "document async capture target latch")
+write(path, s)
+
+print("M3 viewed-device / capture-target separation applied successfully")

From a921fc8e3a48f8f8d95d30015b9e6f93bc6fde1f Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 09:17:19 +0700
Subject: [PATCH 24/84] chore: run guarded M3 capture target latch migration

---
 .../workflows/fat-m3-latch-capture-target.yml | 39 +++++++++++++++++++
 1 file changed, 39 insertions(+)
 create mode 100644 .github/workflows/fat-m3-latch-capture-target.yml

diff --git a/.github/workflows/fat-m3-latch-capture-target.yml b/.github/workflows/fat-m3-latch-capture-target.yml
new file mode 100644
index 000000000..f4f574b5f
--- /dev/null
+++ b/.github/workflows/fat-m3-latch-capture-target.yml
@@ -0,0 +1,39 @@
+name: FAT M3 capture target latch migration
+
+on:
+  push:
+    branches:
+      - fix/fat-workstation-convergence
+    paths:
+      - .github/workflows/fat-m3-latch-capture-target.yml
+      - tools/fat_m3_latch_capture_target.py
+
+permissions:
+  contents: write
+
+jobs:
+  migrate:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout staging branch
+        uses: actions/checkout@v4
+        with:
+          ref: fix/fat-workstation-convergence
+          fetch-depth: 0
+
+      - name: Apply guarded M3 migration
+        run: python tools/fat_m3_latch_capture_target.py
+
+      - name: Remove one-shot migration helpers
+        run: |
+          rm tools/fat_m3_latch_capture_target.py
+          rm .github/workflows/fat-m3-latch-capture-target.yml
+
+      - name: Commit M3 source changes
+        shell: bash
+        run: |
+          git config user.name "github-actions[bot]"
+          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
+          git add -A
+          git commit -m "feat: start M3 selected IED binding with capture target latch"
+          git push origin HEAD:fix/fat-workstation-convergence

From 3d6a019e8f3634c57d721770cabbf45b191c4c87 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]"
 <41898282+github-actions[bot]@users.noreply.github.com>
Date: Thu, 10 Sep 2026 02:17:27 +0000
Subject: [PATCH 25/84] feat: start M3 selected IED binding with capture target
 latch

---
 .../workflows/fat-m3-latch-capture-target.yml | 39 --------------
 ...stTestingWindow.EmbeddedEngineeringHost.cs |  5 +-
 IoListTestingWindow.xaml.cs                   |  2 +
 .../IoTestMultiSessionCoordinator.cs          |  4 +-
 tools/fat_m3_latch_capture_target.py          | 54 -------------------
 5 files changed, 8 insertions(+), 96 deletions(-)
 delete mode 100644 .github/workflows/fat-m3-latch-capture-target.yml
 delete mode 100644 tools/fat_m3_latch_capture_target.py

diff --git a/.github/workflows/fat-m3-latch-capture-target.yml b/.github/workflows/fat-m3-latch-capture-target.yml
deleted file mode 100644
index f4f574b5f..000000000
--- a/.github/workflows/fat-m3-latch-capture-target.yml
+++ /dev/null
@@ -1,39 +0,0 @@
-name: FAT M3 capture target latch migration
-
-on:
-  push:
-    branches:
-      - fix/fat-workstation-convergence
-    paths:
-      - .github/workflows/fat-m3-latch-capture-target.yml
-      - tools/fat_m3_latch_capture_target.py
-
-permissions:
-  contents: write
-
-jobs:
-  migrate:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout staging branch
-        uses: actions/checkout@v4
-        with:
-          ref: fix/fat-workstation-convergence
-          fetch-depth: 0
-
-      - name: Apply guarded M3 migration
-        run: python tools/fat_m3_latch_capture_target.py
-
-      - name: Remove one-shot migration helpers
-        run: |
-          rm tools/fat_m3_latch_capture_target.py
-          rm .github/workflows/fat-m3-latch-capture-target.yml
-
-      - name: Commit M3 source changes
-        shell: bash
-        run: |
-          git config user.name "github-actions[bot]"
-          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
-          git add -A
-          git commit -m "feat: start M3 selected IED binding with capture target latch"
-          git push origin HEAD:fix/fat-workstation-convergence
diff --git a/IoListTestingWindow.EmbeddedEngineeringHost.cs b/IoListTestingWindow.EmbeddedEngineeringHost.cs
index e8955f24a..b17157c60 100644
--- a/IoListTestingWindow.EmbeddedEngineeringHost.cs
+++ b/IoListTestingWindow.EmbeddedEngineeringHost.cs
@@ -214,8 +214,9 @@ internal void SelectEngineeringDeviceForEmbeddedFat(Iec61850MonitorDevice? devic
         if (match == null || ReferenceEquals(SelectedIed, match))
             return;
 
-        // Do not retarget an active production FAT transaction/session. When idle, the
-        // persistent Engineering IED Explorer is the navigation/selection authority.
+        // M3 viewed-device contract: the persistent Engineering IED Explorer owns
+        // what the FAT grid displays. SelectedIed/Session.SelectContext changes only that
+        // projection; an active capture remains latched inside its per-IED controller.
         if (!CanSelectIed)
             return;
 
diff --git a/IoListTestingWindow.xaml.cs b/IoListTestingWindow.xaml.cs
index 84f37fb94..3d23341be 100644
--- a/IoListTestingWindow.xaml.cs
+++ b/IoListTestingWindow.xaml.cs
@@ -119,6 +119,8 @@ private void SetAddingFatIeds(bool value)
 
     private async void StartSession_Click(object sender, RoutedEventArgs e)
     {
+        // Capture target latch: keep this local IED for the complete async prepare +
+        // Start transaction even if the global Engineering Explorer changes selection.
         var selectedIed = SelectedIed;
         if (selectedIed?.IsPreparing == true)
             return;
diff --git a/Services/IoTesting/IoTestMultiSessionCoordinator.cs b/Services/IoTesting/IoTestMultiSessionCoordinator.cs
index 12037ac36..e80146dd7 100644
--- a/Services/IoTesting/IoTestMultiSessionCoordinator.cs
+++ b/Services/IoTesting/IoTestMultiSessionCoordinator.cs
@@ -133,7 +133,9 @@ public IoTestSessionActionResult Start(
         if (ied == null)
             return IoTestSessionActionResult.Failure("Select an imported IED first.");
 
-        SelectContext(ied);
+        // M3: the caller latches the capture target before any asynchronous IED
+        // preparation. Starting that target must never steal the Explorer/view context
+        // if the operator selected another IED while preparation was in flight.
         IoTestSessionController controller;
         try
         {
diff --git a/tools/fat_m3_latch_capture_target.py b/tools/fat_m3_latch_capture_target.py
deleted file mode 100644
index 68d63c899..000000000
--- a/tools/fat_m3_latch_capture_target.py
+++ /dev/null
@@ -1,54 +0,0 @@
-from pathlib import Path
-
-ROOT = Path(__file__).resolve().parents[1]
-
-
-def read(path):
-    return (ROOT / path).read_text(encoding="utf-8")
-
-
-def write(path, text):
-    (ROOT / path).write_text(text, encoding="utf-8")
-
-
-def replace_once(text, old, new, label):
-    count = text.count(old)
-    if count != 1:
-        raise SystemExit(f"{label}: expected exactly 1 match, found {count}")
-    return text.replace(old, new, 1)
-
-
-# M3.1 - Start is a capture-target operation, never a viewed-context operation.
-path = "Services/IoTesting/IoTestMultiSessionCoordinator.cs"
-s = read(path)
-s = replace_once(
-    s,
-    "        SelectContext(ied);\n        IoTestSessionController controller;",
-    "        // M3: the caller latches the capture target before any asynchronous IED\n        // preparation. Starting that target must never steal the Explorer/view context\n        // if the operator selected another IED while preparation was in flight.\n        IoTestSessionController controller;",
-    "separate capture Start from viewed SelectContext")
-write(path, s)
-
-
-# M3.2 - Make the embedded Engineering binding contract explicit. SelectedIed is the
-# viewed context; per-IED session controllers remain evidence/capture authority.
-path = "IoListTestingWindow.EmbeddedEngineeringHost.cs"
-s = read(path)
-s = replace_once(
-    s,
-    "        // Do not retarget an active production FAT transaction/session. When idle, the\n        // persistent Engineering IED Explorer is the navigation/selection authority.\n        if (!CanSelectIed)\n            return;",
-    "        // M3 viewed-device contract: the persistent Engineering IED Explorer owns\n        // what the FAT grid displays. SelectedIed/Session.SelectContext changes only that\n        // projection; an active capture remains latched inside its per-IED controller.\n        if (!CanSelectIed)\n            return;",
-    "document viewed-device binding")
-write(path, s)
-
-
-# M3.3 - Document the async latch at the exact point where it is established.
-path = "IoListTestingWindow.xaml.cs"
-s = read(path)
-s = replace_once(
-    s,
-    "        var selectedIed = SelectedIed;\n        if (selectedIed?.IsPreparing == true)",
-    "        // Capture target latch: keep this local IED for the complete async prepare +\n        // Start transaction even if the global Engineering Explorer changes selection.\n        var selectedIed = SelectedIed;\n        if (selectedIed?.IsPreparing == true)",
-    "document async capture target latch")
-write(path, s)
-
-print("M3 viewed-device / capture-target separation applied successfully")

From 9556d6a02c9fe01051d7a03981898340b3a27b61 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 09:17:57 +0700
Subject: [PATCH 26/84] test: lock M3 viewed IED and capture target separation

---
 ...nFatM3SelectedIedBindingRegressionTests.cs | 92 +++++++++++++++++++
 1 file changed, 92 insertions(+)
 create mode 100644 tests/ARSAS.Tests/ProductionFatM3SelectedIedBindingRegressionTests.cs

diff --git a/tests/ARSAS.Tests/ProductionFatM3SelectedIedBindingRegressionTests.cs b/tests/ARSAS.Tests/ProductionFatM3SelectedIedBindingRegressionTests.cs
new file mode 100644
index 000000000..bc99f06e2
--- /dev/null
+++ b/tests/ARSAS.Tests/ProductionFatM3SelectedIedBindingRegressionTests.cs
@@ -0,0 +1,92 @@
+namespace ARSAS.Tests;
+
+public sealed class ProductionFatM3SelectedIedBindingRegressionTests
+{
+    [Fact]
+    public void Start_LatchesCaptureTarget_WithoutTakingOverViewedContext()
+    {
+        var window = Read("IoListTestingWindow.xaml.cs");
+        var coordinator = Read("Services/IoTesting/IoTestMultiSessionCoordinator.cs");
+
+        var latch = window.IndexOf("var selectedIed = SelectedIed;", StringComparison.Ordinal);
+        var prepare = window.IndexOf("await engineeringWindow.PrepareIoTestIedForFatAsync(", latch, StringComparison.Ordinal);
+        var start = window.IndexOf("Session.Start(selectedIed)", latch, StringComparison.Ordinal);
+        Assert.True(latch >= 0, "Start FAT must latch the currently viewed IED before asynchronous preparation.");
+        Assert.True(prepare > latch, "Engineering acquisition must use the latched target.");
+        Assert.True(start > prepare, "The production session must start the same latched target after preparation.");
+
+        var startBody = MethodBody(
+            coordinator,
+            "public IoTestSessionActionResult Start(\n        IoTestIedPlan? ied,\n        IReadOnlyCollection<IoTestPointPlan>? captureScope)",
+            "public IoTestSessionActionResult Pause");
+        Assert.DoesNotContain("SelectContext(ied)", startBody, StringComparison.Ordinal);
+        Assert.Contains("GetOrCreateController(ied)", startBody, StringComparison.Ordinal);
+        Assert.Contains("controller.Start(ied, captureScope)", startBody, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void EngineeringExplorer_RemainsViewedIedAuthority_WhileSessionsMayRun()
+    {
+        var owner = Read("MainWindow.ProductionFatTab.cs");
+        var embedded = Read("IoListTestingWindow.EmbeddedEngineeringHost.cs");
+        var window = Read("IoListTestingWindow.xaml.cs");
+
+        var propertyHandler = MethodBody(
+            owner,
+            "private void ProductionFat_PropertyChanged",
+            "private void ProductionFat_MainTabsSelectionChanged");
+        Assert.Contains("SynchronizeProductionFatSelectedIed(SelectedDevice);", propertyHandler, StringComparison.Ordinal);
+        Assert.DoesNotContain("HasRunningSession", propertyHandler, StringComparison.Ordinal);
+
+        var selectDevice = MethodBody(
+            embedded,
+            "internal void SelectEngineeringDeviceForEmbeddedFat",
+            "internal void NotifyEmbeddedHostActivated");
+        Assert.Contains("SelectedIed = match;", selectDevice, StringComparison.Ordinal);
+        Assert.Contains("LiveDeviceId", selectDevice, StringComparison.Ordinal);
+        Assert.Contains("IpAddress", selectDevice, StringComparison.Ordinal);
+        Assert.Contains("IedName", selectDevice, StringComparison.Ordinal);
+
+        Assert.Contains("public bool CanSelectIed => true;", window, StringComparison.Ordinal);
+        Assert.Contains("Session.SelectContext(_selectedIed);", window, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void EvidenceActions_ResolveOwningActiveController_NotCurrentView()
+    {
+        var coordinator = Read("Services/IoTesting/IoTestMultiSessionCoordinator.cs");
+
+        Assert.Contains("ResolveOwningActiveController", coordinator, StringComparison.Ordinal);
+        Assert.Contains("points.Any(ied.TestPoints.Contains)", coordinator, StringComparison.Ordinal);
+        Assert.Contains("points.Any(point => !owners[0].TestPoints.Contains(point))", coordinator, StringComparison.Ordinal);
+        Assert.Contains("_controllers.TryGetValue(owners[0], out var controller)", coordinator, StringComparison.Ordinal);
+        Assert.Contains("!controller.IsSessionActive", coordinator, StringComparison.Ordinal);
+    }
+
+    private static string MethodBody(string source, string startMarker, string nextMarker)
+    {
+        var start = source.IndexOf(startMarker, StringComparison.Ordinal);
+        Assert.True(start >= 0, $"Missing method marker: {startMarker}");
+        var end = source.IndexOf(nextMarker, start + startMarker.Length, StringComparison.Ordinal);
+        Assert.True(end > start, $"Missing following method marker: {nextMarker}");
+        return source[start..end];
+    }
+
+    private static string Read(string relativePath)
+        => File.ReadAllText(Path.Combine(FindRepoRoot(), relativePath))
+            .Replace("\r\n", "\n", StringComparison.Ordinal);
+
+    private static string FindRepoRoot()
+    {
+        DirectoryInfo? directory = new(AppContext.BaseDirectory);
+        while (directory != null)
+        {
+            if (File.Exists(Path.Combine(directory.FullName, "MainWindow.xaml")) &&
+                Directory.Exists(Path.Combine(directory.FullName, "tests", "ARSAS.Tests")))
+                return directory.FullName;
+            directory = directory.Parent;
+        }
+
+        throw new DirectoryNotFoundException("Could not locate repository root.");
+    }
+}

From 398b00f46302435dc1a78b1b015418cf8702d3d9 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 09:19:58 +0700
Subject: [PATCH 27/84] chore: stage guarded M3 deterministic viewed IED
 binding

---
 tools/fat_m3_view_binding.py | 90 ++++++++++++++++++++++++++++++++++++
 1 file changed, 90 insertions(+)
 create mode 100644 tools/fat_m3_view_binding.py

diff --git a/tools/fat_m3_view_binding.py b/tools/fat_m3_view_binding.py
new file mode 100644
index 000000000..930175fb3
--- /dev/null
+++ b/tools/fat_m3_view_binding.py
@@ -0,0 +1,90 @@
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[1]
+path = ROOT / "IoListTestingWindow.EmbeddedEngineeringHost.cs"
+source = path.read_text(encoding="utf-8")
+
+old = '''    internal void SelectEngineeringDeviceForEmbeddedFat(Iec61850MonitorDevice? device)
+    {
+        if (!_engineeringEmbeddedMounted || device == null)
+            return;
+
+        var match = Project.Ieds.FirstOrDefault(ied =>
+            (!string.IsNullOrWhiteSpace(ied.LiveDeviceId) &&
+             ied.LiveDeviceId.Equals(device.DeviceId, StringComparison.OrdinalIgnoreCase)) ||
+            (!string.IsNullOrWhiteSpace(ied.IpAddress) &&
+             ied.IpAddress.Equals(device.IpAddress, StringComparison.OrdinalIgnoreCase)) ||
+            ied.IedName.Equals(device.SclIedName, StringComparison.OrdinalIgnoreCase) ||
+            ied.IedName.Equals(device.Name, StringComparison.OrdinalIgnoreCase));
+        if (match == null || ReferenceEquals(SelectedIed, match))
+            return;
+
+        // M3 viewed-device contract: the persistent Engineering IED Explorer owns
+        // what the FAT grid displays. SelectedIed/Session.SelectContext changes only that
+        // projection; an active capture remains latched inside its per-IED controller.
+        if (!CanSelectIed)
+            return;
+
+        SelectedIed = match;
+    }
+'''
+
+new = '''    internal void SelectEngineeringDeviceForEmbeddedFat(Iec61850MonitorDevice? device)
+    {
+        if (!_engineeringEmbeddedMounted)
+            return;
+
+        // M3 viewed-device contract: the persistent Engineering IED Explorer owns
+        // what the FAT grid displays. SelectedIed/Session.SelectContext changes only that
+        // projection; an active capture remains latched inside its per-IED controller.
+        // Clearing the Explorer selection or selecting an IED outside this FAT projection
+        // must clear the FAT view instead of silently leaving the previous IED on screen.
+        if (device == null)
+        {
+            if (CanSelectIed)
+                SelectedIed = null;
+            return;
+        }
+
+        // Resolve by strongest Engineering identity first. Do not use one OR predicate:
+        // a weak fallback on an earlier project row must never beat an exact live DeviceId.
+        IoTestIedPlan? match = null;
+        if (!string.IsNullOrWhiteSpace(device.DeviceId))
+        {
+            match = Project.Ieds.FirstOrDefault(ied =>
+                !string.IsNullOrWhiteSpace(ied.LiveDeviceId) &&
+                ied.LiveDeviceId.Equals(device.DeviceId, StringComparison.OrdinalIgnoreCase));
+        }
+
+        if (match == null && !string.IsNullOrWhiteSpace(device.SclIedName))
+        {
+            match = Project.Ieds.FirstOrDefault(ied =>
+                ied.IedName.Equals(device.SclIedName, StringComparison.OrdinalIgnoreCase));
+        }
+
+        if (match == null && !string.IsNullOrWhiteSpace(device.Name))
+        {
+            match = Project.Ieds.FirstOrDefault(ied =>
+                ied.IedName.Equals(device.Name, StringComparison.OrdinalIgnoreCase));
+        }
+
+        if (match == null && !string.IsNullOrWhiteSpace(device.IpAddress))
+        {
+            match = Project.Ieds.FirstOrDefault(ied =>
+                !string.IsNullOrWhiteSpace(ied.IpAddress) &&
+                ied.IpAddress.Equals(device.IpAddress, StringComparison.OrdinalIgnoreCase));
+        }
+
+        if (ReferenceEquals(SelectedIed, match) || !CanSelectIed)
+            return;
+
+        SelectedIed = match;
+    }
+'''
+
+count = source.count(old)
+if count != 1:
+    raise SystemExit(f"M3 view binding guard: expected exactly one old method, found {count}")
+
+path.write_text(source.replace(old, new, 1), encoding="utf-8")
+print("M3 deterministic Engineering viewed-IED binding applied")

From ea3cb2994fa7feabd24e78db1642b8b8b9667c55 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 09:20:10 +0700
Subject: [PATCH 28/84] chore: run guarded M3 deterministic viewed IED binding
 migration

---
 .github/workflows/fat-m3-view-binding.yml | 39 +++++++++++++++++++++++
 1 file changed, 39 insertions(+)
 create mode 100644 .github/workflows/fat-m3-view-binding.yml

diff --git a/.github/workflows/fat-m3-view-binding.yml b/.github/workflows/fat-m3-view-binding.yml
new file mode 100644
index 000000000..8abc83d8b
--- /dev/null
+++ b/.github/workflows/fat-m3-view-binding.yml
@@ -0,0 +1,39 @@
+name: FAT M3 deterministic view binding migration
+
+on:
+  push:
+    branches:
+      - fix/fat-workstation-convergence
+    paths:
+      - .github/workflows/fat-m3-view-binding.yml
+      - tools/fat_m3_view_binding.py
+
+permissions:
+  contents: write
+
+jobs:
+  migrate:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout staging branch
+        uses: actions/checkout@v4
+        with:
+          ref: fix/fat-workstation-convergence
+          fetch-depth: 0
+
+      - name: Apply guarded M3 view binding migration
+        run: python tools/fat_m3_view_binding.py
+
+      - name: Remove one-shot migration helpers
+        run: |
+          rm tools/fat_m3_view_binding.py
+          rm .github/workflows/fat-m3-view-binding.yml
+
+      - name: Commit M3 view binding changes
+        shell: bash
+        run: |
+          git config user.name "github-actions[bot]"
+          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
+          git add -A
+          git commit -m "feat: make M3 Engineering IED view binding deterministic"
+          git push origin HEAD:fix/fat-workstation-convergence

From ae0f0f3d584b85e08a6bb1a75b2a7995340812f4 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]"
 <41898282+github-actions[bot]@users.noreply.github.com>
Date: Thu, 10 Sep 2026 02:20:18 +0000
Subject: [PATCH 29/84] feat: make M3 Engineering IED view binding
 deterministic

---
 .github/workflows/fat-m3-view-binding.yml     | 39 --------
 ...stTestingWindow.EmbeddedEngineeringHost.cs | 52 ++++++++---
 tools/fat_m3_view_binding.py                  | 90 -------------------
 3 files changed, 40 insertions(+), 141 deletions(-)
 delete mode 100644 .github/workflows/fat-m3-view-binding.yml
 delete mode 100644 tools/fat_m3_view_binding.py

diff --git a/.github/workflows/fat-m3-view-binding.yml b/.github/workflows/fat-m3-view-binding.yml
deleted file mode 100644
index 8abc83d8b..000000000
--- a/.github/workflows/fat-m3-view-binding.yml
+++ /dev/null
@@ -1,39 +0,0 @@
-name: FAT M3 deterministic view binding migration
-
-on:
-  push:
-    branches:
-      - fix/fat-workstation-convergence
-    paths:
-      - .github/workflows/fat-m3-view-binding.yml
-      - tools/fat_m3_view_binding.py
-
-permissions:
-  contents: write
-
-jobs:
-  migrate:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout staging branch
-        uses: actions/checkout@v4
-        with:
-          ref: fix/fat-workstation-convergence
-          fetch-depth: 0
-
-      - name: Apply guarded M3 view binding migration
-        run: python tools/fat_m3_view_binding.py
-
-      - name: Remove one-shot migration helpers
-        run: |
-          rm tools/fat_m3_view_binding.py
-          rm .github/workflows/fat-m3-view-binding.yml
-
-      - name: Commit M3 view binding changes
-        shell: bash
-        run: |
-          git config user.name "github-actions[bot]"
-          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
-          git add -A
-          git commit -m "feat: make M3 Engineering IED view binding deterministic"
-          git push origin HEAD:fix/fat-workstation-convergence
diff --git a/IoListTestingWindow.EmbeddedEngineeringHost.cs b/IoListTestingWindow.EmbeddedEngineeringHost.cs
index b17157c60..acd032625 100644
--- a/IoListTestingWindow.EmbeddedEngineeringHost.cs
+++ b/IoListTestingWindow.EmbeddedEngineeringHost.cs
@@ -201,23 +201,51 @@ private void DisableLegacyEmbeddedCommandPanel()
 
     internal void SelectEngineeringDeviceForEmbeddedFat(Iec61850MonitorDevice? device)
     {
-        if (!_engineeringEmbeddedMounted || device == null)
-            return;
-
-        var match = Project.Ieds.FirstOrDefault(ied =>
-            (!string.IsNullOrWhiteSpace(ied.LiveDeviceId) &&
-             ied.LiveDeviceId.Equals(device.DeviceId, StringComparison.OrdinalIgnoreCase)) ||
-            (!string.IsNullOrWhiteSpace(ied.IpAddress) &&
-             ied.IpAddress.Equals(device.IpAddress, StringComparison.OrdinalIgnoreCase)) ||
-            ied.IedName.Equals(device.SclIedName, StringComparison.OrdinalIgnoreCase) ||
-            ied.IedName.Equals(device.Name, StringComparison.OrdinalIgnoreCase));
-        if (match == null || ReferenceEquals(SelectedIed, match))
+        if (!_engineeringEmbeddedMounted)
             return;
 
         // M3 viewed-device contract: the persistent Engineering IED Explorer owns
         // what the FAT grid displays. SelectedIed/Session.SelectContext changes only that
         // projection; an active capture remains latched inside its per-IED controller.
-        if (!CanSelectIed)
+        // Clearing the Explorer selection or selecting an IED outside this FAT projection
+        // must clear the FAT view instead of silently leaving the previous IED on screen.
+        if (device == null)
+        {
+            if (CanSelectIed)
+                SelectedIed = null;
+            return;
+        }
+
+        // Resolve by strongest Engineering identity first. Do not use one OR predicate:
+        // a weak fallback on an earlier project row must never beat an exact live DeviceId.
+        IoTestIedPlan? match = null;
+        if (!string.IsNullOrWhiteSpace(device.DeviceId))
+        {
+            match = Project.Ieds.FirstOrDefault(ied =>
+                !string.IsNullOrWhiteSpace(ied.LiveDeviceId) &&
+                ied.LiveDeviceId.Equals(device.DeviceId, StringComparison.OrdinalIgnoreCase));
+        }
+
+        if (match == null && !string.IsNullOrWhiteSpace(device.SclIedName))
+        {
+            match = Project.Ieds.FirstOrDefault(ied =>
+                ied.IedName.Equals(device.SclIedName, StringComparison.OrdinalIgnoreCase));
+        }
+
+        if (match == null && !string.IsNullOrWhiteSpace(device.Name))
+        {
+            match = Project.Ieds.FirstOrDefault(ied =>
+                ied.IedName.Equals(device.Name, StringComparison.OrdinalIgnoreCase));
+        }
+
+        if (match == null && !string.IsNullOrWhiteSpace(device.IpAddress))
+        {
+            match = Project.Ieds.FirstOrDefault(ied =>
+                !string.IsNullOrWhiteSpace(ied.IpAddress) &&
+                ied.IpAddress.Equals(device.IpAddress, StringComparison.OrdinalIgnoreCase));
+        }
+
+        if (ReferenceEquals(SelectedIed, match) || !CanSelectIed)
             return;
 
         SelectedIed = match;
diff --git a/tools/fat_m3_view_binding.py b/tools/fat_m3_view_binding.py
deleted file mode 100644
index 930175fb3..000000000
--- a/tools/fat_m3_view_binding.py
+++ /dev/null
@@ -1,90 +0,0 @@
-from pathlib import Path
-
-ROOT = Path(__file__).resolve().parents[1]
-path = ROOT / "IoListTestingWindow.EmbeddedEngineeringHost.cs"
-source = path.read_text(encoding="utf-8")
-
-old = '''    internal void SelectEngineeringDeviceForEmbeddedFat(Iec61850MonitorDevice? device)
-    {
-        if (!_engineeringEmbeddedMounted || device == null)
-            return;
-
-        var match = Project.Ieds.FirstOrDefault(ied =>
-            (!string.IsNullOrWhiteSpace(ied.LiveDeviceId) &&
-             ied.LiveDeviceId.Equals(device.DeviceId, StringComparison.OrdinalIgnoreCase)) ||
-            (!string.IsNullOrWhiteSpace(ied.IpAddress) &&
-             ied.IpAddress.Equals(device.IpAddress, StringComparison.OrdinalIgnoreCase)) ||
-            ied.IedName.Equals(device.SclIedName, StringComparison.OrdinalIgnoreCase) ||
-            ied.IedName.Equals(device.Name, StringComparison.OrdinalIgnoreCase));
-        if (match == null || ReferenceEquals(SelectedIed, match))
-            return;
-
-        // M3 viewed-device contract: the persistent Engineering IED Explorer owns
-        // what the FAT grid displays. SelectedIed/Session.SelectContext changes only that
-        // projection; an active capture remains latched inside its per-IED controller.
-        if (!CanSelectIed)
-            return;
-
-        SelectedIed = match;
-    }
-'''
-
-new = '''    internal void SelectEngineeringDeviceForEmbeddedFat(Iec61850MonitorDevice? device)
-    {
-        if (!_engineeringEmbeddedMounted)
-            return;
-
-        // M3 viewed-device contract: the persistent Engineering IED Explorer owns
-        // what the FAT grid displays. SelectedIed/Session.SelectContext changes only that
-        // projection; an active capture remains latched inside its per-IED controller.
-        // Clearing the Explorer selection or selecting an IED outside this FAT projection
-        // must clear the FAT view instead of silently leaving the previous IED on screen.
-        if (device == null)
-        {
-            if (CanSelectIed)
-                SelectedIed = null;
-            return;
-        }
-
-        // Resolve by strongest Engineering identity first. Do not use one OR predicate:
-        // a weak fallback on an earlier project row must never beat an exact live DeviceId.
-        IoTestIedPlan? match = null;
-        if (!string.IsNullOrWhiteSpace(device.DeviceId))
-        {
-            match = Project.Ieds.FirstOrDefault(ied =>
-                !string.IsNullOrWhiteSpace(ied.LiveDeviceId) &&
-                ied.LiveDeviceId.Equals(device.DeviceId, StringComparison.OrdinalIgnoreCase));
-        }
-
-        if (match == null && !string.IsNullOrWhiteSpace(device.SclIedName))
-        {
-            match = Project.Ieds.FirstOrDefault(ied =>
-                ied.IedName.Equals(device.SclIedName, StringComparison.OrdinalIgnoreCase));
-        }
-
-        if (match == null && !string.IsNullOrWhiteSpace(device.Name))
-        {
-            match = Project.Ieds.FirstOrDefault(ied =>
-                ied.IedName.Equals(device.Name, StringComparison.OrdinalIgnoreCase));
-        }
-
-        if (match == null && !string.IsNullOrWhiteSpace(device.IpAddress))
-        {
-            match = Project.Ieds.FirstOrDefault(ied =>
-                !string.IsNullOrWhiteSpace(ied.IpAddress) &&
-                ied.IpAddress.Equals(device.IpAddress, StringComparison.OrdinalIgnoreCase));
-        }
-
-        if (ReferenceEquals(SelectedIed, match) || !CanSelectIed)
-            return;
-
-        SelectedIed = match;
-    }
-'''
-
-count = source.count(old)
-if count != 1:
-    raise SystemExit(f"M3 view binding guard: expected exactly one old method, found {count}")
-
-path.write_text(source.replace(old, new, 1), encoding="utf-8")
-print("M3 deterministic Engineering viewed-IED binding applied")

From dd1343aee90a77bf64cb944e812576d3296240f5 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 09:21:06 +0700
Subject: [PATCH 30/84] test: lock final M3 Explorer-to-FAT binding contract

---
 ...nFatM3SelectedIedBindingRegressionTests.cs | 23 ++++++++++++-------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/tests/ARSAS.Tests/ProductionFatM3SelectedIedBindingRegressionTests.cs b/tests/ARSAS.Tests/ProductionFatM3SelectedIedBindingRegressionTests.cs
index bc99f06e2..31c628f40 100644
--- a/tests/ARSAS.Tests/ProductionFatM3SelectedIedBindingRegressionTests.cs
+++ b/tests/ARSAS.Tests/ProductionFatM3SelectedIedBindingRegressionTests.cs
@@ -33,22 +33,29 @@ public void EngineeringExplorer_RemainsViewedIedAuthority_WhileSessionsMayRun()
 
         var propertyHandler = MethodBody(
             owner,
-            "private void ProductionFat_PropertyChanged",
-            "private void ProductionFat_MainTabsSelectionChanged");
-        Assert.Contains("SynchronizeProductionFatSelectedIed(SelectedDevice);", propertyHandler, StringComparison.Ordinal);
+            "private void ProductionFat_MainWindowPropertyChanged",
+            "private void SynchronizeProductionFatSelectedIed()");
+        Assert.Contains("e.PropertyName == nameof(SelectedDevice)", propertyHandler, StringComparison.Ordinal);
+        Assert.Contains("SynchronizeProductionFatSelectedIed();", propertyHandler, StringComparison.Ordinal);
         Assert.DoesNotContain("HasRunningSession", propertyHandler, StringComparison.Ordinal);
 
         var selectDevice = MethodBody(
             embedded,
             "internal void SelectEngineeringDeviceForEmbeddedFat",
             "internal void NotifyEmbeddedHostActivated");
+        Assert.Contains("SelectedIed = null;", selectDevice, StringComparison.Ordinal);
         Assert.Contains("SelectedIed = match;", selectDevice, StringComparison.Ordinal);
-        Assert.Contains("LiveDeviceId", selectDevice, StringComparison.Ordinal);
-        Assert.Contains("IpAddress", selectDevice, StringComparison.Ordinal);
-        Assert.Contains("IedName", selectDevice, StringComparison.Ordinal);
-
+        Assert.Contains("Session.SelectContext", window, StringComparison.Ordinal);
         Assert.Contains("public bool CanSelectIed => true;", window, StringComparison.Ordinal);
-        Assert.Contains("Session.SelectContext(_selectedIed);", window, StringComparison.Ordinal);
+
+        var deviceId = selectDevice.IndexOf("device.DeviceId", StringComparison.Ordinal);
+        var sclIedName = selectDevice.IndexOf("device.SclIedName", StringComparison.Ordinal);
+        var displayName = selectDevice.IndexOf("device.Name", StringComparison.Ordinal);
+        var ipAddress = selectDevice.IndexOf("device.IpAddress", StringComparison.Ordinal);
+        Assert.True(deviceId >= 0, "Engineering DeviceId must be the strongest view identity.");
+        Assert.True(sclIedName > deviceId, "SCL IED identity must follow DeviceId fallback.");
+        Assert.True(displayName > sclIedName, "Engineering display name must be weaker than SCL identity.");
+        Assert.True(ipAddress > displayName, "IP address must be the final view-binding fallback.");
     }
 
     [Fact]

From effc8f95b3036593c41117fa037564fea8b79f9b Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 09:26:10 +0700
Subject: [PATCH 31/84] M3: infer production IED plan type for selected-device
 binding

---
 IoListTestingWindow.EmbeddedEngineeringHost.cs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/IoListTestingWindow.EmbeddedEngineeringHost.cs b/IoListTestingWindow.EmbeddedEngineeringHost.cs
index acd032625..d5dfe0478 100644
--- a/IoListTestingWindow.EmbeddedEngineeringHost.cs
+++ b/IoListTestingWindow.EmbeddedEngineeringHost.cs
@@ -218,7 +218,7 @@ internal void SelectEngineeringDeviceForEmbeddedFat(Iec61850MonitorDevice? devic
 
         // Resolve by strongest Engineering identity first. Do not use one OR predicate:
         // a weak fallback on an earlier project row must never beat an exact live DeviceId.
-        IoTestIedPlan? match = null;
+        var match = Project.Ieds.FirstOrDefault(_ => false);
         if (!string.IsNullOrWhiteSpace(device.DeviceId))
         {
             match = Project.Ieds.FirstOrDefault(ied =>

From ec4b65c9e2641e21ce1bb011f0bf79f875f9b8ed Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 09:38:25 +0700
Subject: [PATCH 32/84] chore: stage M3 persistence ownership guard

---
 tools/fat_m3_persistence_guard.py | 92 +++++++++++++++++++++++++++++++
 1 file changed, 92 insertions(+)
 create mode 100644 tools/fat_m3_persistence_guard.py

diff --git a/tools/fat_m3_persistence_guard.py b/tools/fat_m3_persistence_guard.py
new file mode 100644
index 000000000..897cdebda
--- /dev/null
+++ b/tools/fat_m3_persistence_guard.py
@@ -0,0 +1,92 @@
+from pathlib import Path
+
+bootstrap_path = Path("Services/IoTesting/IoTestWorkspaceBootstrapService.cs")
+test_path = Path("tests/ARSAS.Tests/IoFatPhaseBPerIedRestoreRegressionTests.cs")
+
+bootstrap = bootstrap_path.read_text(encoding="utf-8")
+old = '''        try
+        {
+            if (!string.IsNullOrWhiteSpace(restoreSnapshotPath) && File.Exists(restoreSnapshotPath))
+            {
+                try
+                {
+                    ApplySnapshotProgress(importedProject, restoreSnapshotPath);
+                    restored = true;
+
+                    // The snapshot at the canonical current path is temporarily moved so
+                    // persistence cannot replace the freshly imported IEC model wholesale.
+                    // A compatible SCL snapshot discovered under an older staging/project
+                    // identity is read-only input; the new current path is saved normally.
+                    if (restoreSnapshotPath.Equals(snapshotPath, StringComparison.OrdinalIgnoreCase))
+                    {
+                        Directory.CreateDirectory(localDirectory);
+                        File.Move(snapshotPath, backupPath, true);
+                        movedSnapshot = true;
+                    }
+                }
+                catch (Exception ex) when (ex is IOException or JsonException or InvalidDataException)
+                {
+                    warnings.Add($"Local progress could not be restored; a fresh FAT workspace was opened: {ex.Message}");
+                }
+            }
+'''
+new = '''        try
+        {
+            if (!string.IsNullOrWhiteSpace(restoreSnapshotPath) && File.Exists(restoreSnapshotPath))
+            {
+                // Isolate the canonical persisted snapshot BEFORE attempting selective restore.
+                // Otherwise a rejected/invalid partial restore could fall through to
+                // IoTestWorkspacePersistence.OpenSourcesAsync(), which is allowed to restore a
+                // matching snapshot wholesale. Engineering is the fresh plan authority here:
+                // the old snapshot is read-only evidence input, never a replacement project.
+                if (restoreSnapshotPath.Equals(snapshotPath, StringComparison.OrdinalIgnoreCase))
+                {
+                    Directory.CreateDirectory(localDirectory);
+                    File.Move(snapshotPath, backupPath, true);
+                    movedSnapshot = true;
+                    restoreSnapshotPath = backupPath;
+                }
+
+                try
+                {
+                    ApplySnapshotProgress(importedProject, restoreSnapshotPath);
+                    restored = true;
+                }
+                catch (Exception ex) when (ex is IOException or JsonException or InvalidDataException)
+                {
+                    warnings.Add($"Local progress could not be restored; a fresh FAT workspace was opened: {ex.Message}");
+                }
+            }
+'''
+if bootstrap.count(old) != 1:
+    raise SystemExit(f"bootstrap guard expected exactly once, found {bootstrap.count(old)}")
+bootstrap = bootstrap.replace(old, new)
+bootstrap_path.write_text(bootstrap, encoding="utf-8")
+
+test = test_path.read_text(encoding="utf-8")
+old_test = '''        using (reopened.Session)
+        using (reopened.Workspace)
+        {
+            var point = reopened.Project.Ieds.Single().TestPoints.Single();
+            Assert.Equal(IoTestPointState.NotStarted, point.Runtime.State);
+            Assert.Null(point.Runtime.OnEvidence);
+            Assert.Null(point.Runtime.OffEvidence);
+        }
+'''
+new_test = '''        using (reopened.Session)
+        using (reopened.Workspace)
+        {
+            // Bootstrap must keep the freshly imported Engineering plan as authority. A
+            // persistence candidate may contribute progress only after IED ownership matches;
+            // it must never replace the current project wholesale.
+            Assert.Same(current, reopened.Project);
+            var point = reopened.Project.Ieds.Single().TestPoints.Single();
+            Assert.Equal(IoTestPointState.NotStarted, point.Runtime.State);
+            Assert.Null(point.Runtime.OnEvidence);
+            Assert.Null(point.Runtime.OffEvidence);
+        }
+'''
+if test.count(old_test) != 1:
+    raise SystemExit(f"test guard expected exactly once, found {test.count(old_test)}")
+test = test.replace(old_test, new_test)
+test_path.write_text(test, encoding="utf-8")

From e216eae67644ca75f81be62a1299d24f33fe153b Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 09:38:38 +0700
Subject: [PATCH 33/84] chore: run guarded M3 persistence migration

---
 .../workflows/fat-m3-persistence-guard.yml    | 35 +++++++++++++++++++
 1 file changed, 35 insertions(+)
 create mode 100644 .github/workflows/fat-m3-persistence-guard.yml

diff --git a/.github/workflows/fat-m3-persistence-guard.yml b/.github/workflows/fat-m3-persistence-guard.yml
new file mode 100644
index 000000000..4ef303245
--- /dev/null
+++ b/.github/workflows/fat-m3-persistence-guard.yml
@@ -0,0 +1,35 @@
+name: FAT M3 persistence guard
+
+on:
+  push:
+    branches:
+      - fix/fat-workstation-convergence
+    paths:
+      - '.github/workflows/fat-m3-persistence-guard.yml'
+
+permissions:
+  contents: write
+
+jobs:
+  migrate:
+    if: github.repository == 'masarray/arsas'
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          ref: fix/fat-workstation-convergence
+          fetch-depth: 0
+      - name: Apply guarded ownership patch
+        run: python3 tools/fat_m3_persistence_guard.py
+      - name: Remove one-shot helpers
+        run: |
+          rm tools/fat_m3_persistence_guard.py
+          rm .github/workflows/fat-m3-persistence-guard.yml
+      - name: Commit generated source patch
+        run: |
+          git config user.name "github-actions[bot]"
+          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
+          git add -A
+          git diff --cached --check
+          git commit -m "M3: fail closed on per-IED persistence restore"
+          git push origin HEAD:fix/fat-workstation-convergence

From b52843ad6b27845c07105f7cfa8330cc4f122b67 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]"
 <41898282+github-actions[bot]@users.noreply.github.com>
Date: Thu, 10 Sep 2026 02:38:46 +0000
Subject: [PATCH 34/84] M3: fail closed on per-IED persistence restore

---
 .../workflows/fat-m3-persistence-guard.yml    | 35 -------
 .../IoTestWorkspaceBootstrapService.cs        | 24 ++---
 ...IoFatPhaseBPerIedRestoreRegressionTests.cs |  4 +
 tools/fat_m3_persistence_guard.py             | 92 -------------------
 4 files changed, 17 insertions(+), 138 deletions(-)
 delete mode 100644 .github/workflows/fat-m3-persistence-guard.yml
 delete mode 100644 tools/fat_m3_persistence_guard.py

diff --git a/.github/workflows/fat-m3-persistence-guard.yml b/.github/workflows/fat-m3-persistence-guard.yml
deleted file mode 100644
index 4ef303245..000000000
--- a/.github/workflows/fat-m3-persistence-guard.yml
+++ /dev/null
@@ -1,35 +0,0 @@
-name: FAT M3 persistence guard
-
-on:
-  push:
-    branches:
-      - fix/fat-workstation-convergence
-    paths:
-      - '.github/workflows/fat-m3-persistence-guard.yml'
-
-permissions:
-  contents: write
-
-jobs:
-  migrate:
-    if: github.repository == 'masarray/arsas'
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          ref: fix/fat-workstation-convergence
-          fetch-depth: 0
-      - name: Apply guarded ownership patch
-        run: python3 tools/fat_m3_persistence_guard.py
-      - name: Remove one-shot helpers
-        run: |
-          rm tools/fat_m3_persistence_guard.py
-          rm .github/workflows/fat-m3-persistence-guard.yml
-      - name: Commit generated source patch
-        run: |
-          git config user.name "github-actions[bot]"
-          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
-          git add -A
-          git diff --cached --check
-          git commit -m "M3: fail closed on per-IED persistence restore"
-          git push origin HEAD:fix/fat-workstation-convergence
diff --git a/Services/IoTesting/IoTestWorkspaceBootstrapService.cs b/Services/IoTesting/IoTestWorkspaceBootstrapService.cs
index 72d02b943..dd5ec3e8d 100644
--- a/Services/IoTesting/IoTestWorkspaceBootstrapService.cs
+++ b/Services/IoTesting/IoTestWorkspaceBootstrapService.cs
@@ -61,21 +61,23 @@ public static async Task<IoTestWorkspaceLaunchResult> OpenSourcesAsync(
         {
             if (!string.IsNullOrWhiteSpace(restoreSnapshotPath) && File.Exists(restoreSnapshotPath))
             {
+                // Isolate the canonical persisted snapshot BEFORE attempting selective restore.
+                // Otherwise a rejected/invalid partial restore could fall through to
+                // IoTestWorkspacePersistence.OpenSourcesAsync(), which is allowed to restore a
+                // matching snapshot wholesale. Engineering is the fresh plan authority here:
+                // the old snapshot is read-only evidence input, never a replacement project.
+                if (restoreSnapshotPath.Equals(snapshotPath, StringComparison.OrdinalIgnoreCase))
+                {
+                    Directory.CreateDirectory(localDirectory);
+                    File.Move(snapshotPath, backupPath, true);
+                    movedSnapshot = true;
+                    restoreSnapshotPath = backupPath;
+                }
+
                 try
                 {
                     ApplySnapshotProgress(importedProject, restoreSnapshotPath);
                     restored = true;
-
-                    // The snapshot at the canonical current path is temporarily moved so
-                    // persistence cannot replace the freshly imported IEC model wholesale.
-                    // A compatible SCL snapshot discovered under an older staging/project
-                    // identity is read-only input; the new current path is saved normally.
-                    if (restoreSnapshotPath.Equals(snapshotPath, StringComparison.OrdinalIgnoreCase))
-                    {
-                        Directory.CreateDirectory(localDirectory);
-                        File.Move(snapshotPath, backupPath, true);
-                        movedSnapshot = true;
-                    }
                 }
                 catch (Exception ex) when (ex is IOException or JsonException or InvalidDataException)
                 {
diff --git a/tests/ARSAS.Tests/IoFatPhaseBPerIedRestoreRegressionTests.cs b/tests/ARSAS.Tests/IoFatPhaseBPerIedRestoreRegressionTests.cs
index 4b263b5c0..6e2afdcad 100644
--- a/tests/ARSAS.Tests/IoFatPhaseBPerIedRestoreRegressionTests.cs
+++ b/tests/ARSAS.Tests/IoFatPhaseBPerIedRestoreRegressionTests.cs
@@ -134,6 +134,10 @@ public async Task Reopen_RequiresTechnicalKeyAndIpForIedOwnership()
         using (reopened.Session)
         using (reopened.Workspace)
         {
+            // Bootstrap must keep the freshly imported Engineering plan as authority. A
+            // persistence candidate may contribute progress only after IED ownership matches;
+            // it must never replace the current project wholesale.
+            Assert.Same(current, reopened.Project);
             var point = reopened.Project.Ieds.Single().TestPoints.Single();
             Assert.Equal(IoTestPointState.NotStarted, point.Runtime.State);
             Assert.Null(point.Runtime.OnEvidence);
diff --git a/tools/fat_m3_persistence_guard.py b/tools/fat_m3_persistence_guard.py
deleted file mode 100644
index 897cdebda..000000000
--- a/tools/fat_m3_persistence_guard.py
+++ /dev/null
@@ -1,92 +0,0 @@
-from pathlib import Path
-
-bootstrap_path = Path("Services/IoTesting/IoTestWorkspaceBootstrapService.cs")
-test_path = Path("tests/ARSAS.Tests/IoFatPhaseBPerIedRestoreRegressionTests.cs")
-
-bootstrap = bootstrap_path.read_text(encoding="utf-8")
-old = '''        try
-        {
-            if (!string.IsNullOrWhiteSpace(restoreSnapshotPath) && File.Exists(restoreSnapshotPath))
-            {
-                try
-                {
-                    ApplySnapshotProgress(importedProject, restoreSnapshotPath);
-                    restored = true;
-
-                    // The snapshot at the canonical current path is temporarily moved so
-                    // persistence cannot replace the freshly imported IEC model wholesale.
-                    // A compatible SCL snapshot discovered under an older staging/project
-                    // identity is read-only input; the new current path is saved normally.
-                    if (restoreSnapshotPath.Equals(snapshotPath, StringComparison.OrdinalIgnoreCase))
-                    {
-                        Directory.CreateDirectory(localDirectory);
-                        File.Move(snapshotPath, backupPath, true);
-                        movedSnapshot = true;
-                    }
-                }
-                catch (Exception ex) when (ex is IOException or JsonException or InvalidDataException)
-                {
-                    warnings.Add($"Local progress could not be restored; a fresh FAT workspace was opened: {ex.Message}");
-                }
-            }
-'''
-new = '''        try
-        {
-            if (!string.IsNullOrWhiteSpace(restoreSnapshotPath) && File.Exists(restoreSnapshotPath))
-            {
-                // Isolate the canonical persisted snapshot BEFORE attempting selective restore.
-                // Otherwise a rejected/invalid partial restore could fall through to
-                // IoTestWorkspacePersistence.OpenSourcesAsync(), which is allowed to restore a
-                // matching snapshot wholesale. Engineering is the fresh plan authority here:
-                // the old snapshot is read-only evidence input, never a replacement project.
-                if (restoreSnapshotPath.Equals(snapshotPath, StringComparison.OrdinalIgnoreCase))
-                {
-                    Directory.CreateDirectory(localDirectory);
-                    File.Move(snapshotPath, backupPath, true);
-                    movedSnapshot = true;
-                    restoreSnapshotPath = backupPath;
-                }
-
-                try
-                {
-                    ApplySnapshotProgress(importedProject, restoreSnapshotPath);
-                    restored = true;
-                }
-                catch (Exception ex) when (ex is IOException or JsonException or InvalidDataException)
-                {
-                    warnings.Add($"Local progress could not be restored; a fresh FAT workspace was opened: {ex.Message}");
-                }
-            }
-'''
-if bootstrap.count(old) != 1:
-    raise SystemExit(f"bootstrap guard expected exactly once, found {bootstrap.count(old)}")
-bootstrap = bootstrap.replace(old, new)
-bootstrap_path.write_text(bootstrap, encoding="utf-8")
-
-test = test_path.read_text(encoding="utf-8")
-old_test = '''        using (reopened.Session)
-        using (reopened.Workspace)
-        {
-            var point = reopened.Project.Ieds.Single().TestPoints.Single();
-            Assert.Equal(IoTestPointState.NotStarted, point.Runtime.State);
-            Assert.Null(point.Runtime.OnEvidence);
-            Assert.Null(point.Runtime.OffEvidence);
-        }
-'''
-new_test = '''        using (reopened.Session)
-        using (reopened.Workspace)
-        {
-            // Bootstrap must keep the freshly imported Engineering plan as authority. A
-            // persistence candidate may contribute progress only after IED ownership matches;
-            // it must never replace the current project wholesale.
-            Assert.Same(current, reopened.Project);
-            var point = reopened.Project.Ieds.Single().TestPoints.Single();
-            Assert.Equal(IoTestPointState.NotStarted, point.Runtime.State);
-            Assert.Null(point.Runtime.OnEvidence);
-            Assert.Null(point.Runtime.OffEvidence);
-        }
-'''
-if test.count(old_test) != 1:
-    raise SystemExit(f"test guard expected exactly once, found {test.count(old_test)}")
-test = test.replace(old_test, new_test)
-test_path.write_text(test, encoding="utf-8")

From 10dcbbc4ee9e272369ae2006e58deca49aaa151c Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 09:40:24 +0700
Subject: [PATCH 35/84] M3: lock fail-closed per-IED restore contract

---
 docs/FAT_ENGINEERING_WORKSTATION_CONTRACT.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/docs/FAT_ENGINEERING_WORKSTATION_CONTRACT.md b/docs/FAT_ENGINEERING_WORKSTATION_CONTRACT.md
index 713da2656..6ef530e70 100644
--- a/docs/FAT_ENGINEERING_WORKSTATION_CONTRACT.md
+++ b/docs/FAT_ENGINEERING_WORKSTATION_CONTRACT.md
@@ -40,6 +40,8 @@ When a FAT session starts or continues, the capture target is latched to that se
 
 Persisted FAT state is reconciled by stable device/IEC identity. Background reconciliation is read/reconcile-only and must not manufacture new evidence.
 
+A persisted snapshot is evidence input, not authority to replace the fresh Engineering projection. Bootstrap must isolate a canonical prior snapshot before selective reconciliation. If technical IED identity, endpoint/IP, source identity, or point configuration does not match, restore fails closed and the current Engineering project remains authoritative; lower persistence layers must not recover the rejected snapshot wholesale.
+
 ## Static DataSet authority invariant
 
 Automatic Engineering FAT uses the authoritative static DataSet projection from the already parsed `SclIedWorkspace`.

From 8d1eb7eec92be15f61c2e0909c8a891cdc287731 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 10:10:47 +0700
Subject: [PATCH 36/84] M5: add DeviceId-aware persisted IED ownership guard

---
 .../IoTesting/IoTestPerIedProgressIdentity.cs | 43 ++++++++++++++++++-
 1 file changed, 41 insertions(+), 2 deletions(-)

diff --git a/Services/IoTesting/IoTestPerIedProgressIdentity.cs b/Services/IoTesting/IoTestPerIedProgressIdentity.cs
index 62f220e5c..bb6511531 100644
--- a/Services/IoTesting/IoTestPerIedProgressIdentity.cs
+++ b/Services/IoTesting/IoTestPerIedProgressIdentity.cs
@@ -7,8 +7,9 @@ namespace ArIED61850Tester.Services.IoTesting;
 
 /// <summary>
 /// Stable identity contract for restoring persisted FAT progress onto a freshly imported plan.
-/// IED ownership is technical-key + IP scoped; point progress is accepted only when the
-/// evidence-critical configuration fingerprint still matches.
+/// IED ownership is IEC technical identity + endpoint scoped and, when both sides know it,
+/// additionally bound to the Engineering live DeviceId. Point progress is accepted only when
+/// the evidence-critical configuration fingerprint still matches.
 /// </summary>
 public static class IoTestPerIedProgressIdentity
 {
@@ -21,6 +22,44 @@ public static string IedKey(IoTestIedPlan ied)
     public static string IedKey(string? iedName, string? ipAddress)
         => $"{NormalizeIdentity(iedName)}|{NormalizeIp(ipAddress)}";
 
+    /// <summary>
+    /// Strong persisted-owner key for new snapshots. DeviceId is deliberately additive:
+    /// legacy snapshots did not persist it, so endpoint + IEC identity remains the migration
+    /// fallback only when either side does not yet know a DeviceId. Once both sides know it,
+    /// a mismatch is a hard fail-closed ownership boundary.
+    /// </summary>
+    public static string IedPersistenceAuthorityKey(IoTestIedPlan ied)
+    {
+        ArgumentNullException.ThrowIfNull(ied);
+        return IedPersistenceAuthorityKey(ied.LiveDeviceId, ied.IedName, ied.IpAddress);
+    }
+
+    public static string IedPersistenceAuthorityKey(
+        string? deviceId,
+        string? iedName,
+        string? ipAddress)
+        => $"{NormalizeIdentity(deviceId)}|{NormalizeIdentity(iedName)}|{NormalizeIp(ipAddress)}";
+
+    public static bool PersistedIedOwnershipMatches(IoTestIedPlan currentIed, JsonElement savedIed)
+    {
+        ArgumentNullException.ThrowIfNull(currentIed);
+
+        var savedName = OptionalString(savedIed, "iedName", string.Empty);
+        var savedIp = OptionalString(savedIed, "ipAddress", string.Empty);
+        if (!IedKey(currentIed).Equals(IedKey(savedName, savedIp), StringComparison.Ordinal))
+            return false;
+
+        var currentDeviceId = NormalizeIdentity(currentIed.LiveDeviceId);
+        var savedDeviceId = NormalizeIdentity(OptionalString(savedIed, "liveDeviceId", string.Empty));
+
+        // Backward compatibility is intentionally one-way: old snapshots without DeviceId
+        // may still restore through exact IEC identity + IP + point fingerprints. As soon as
+        // both snapshots/current Engineering context carry DeviceId, it becomes mandatory.
+        return currentDeviceId.Length == 0 ||
+               savedDeviceId.Length == 0 ||
+               currentDeviceId.Equals(savedDeviceId, StringComparison.Ordinal);
+    }
+
     public static string PointConfigurationFingerprint(IoTestPointPlan point)
         => PointConfigurationFingerprintCore(point, includeSignalAddress: true);
 

From 73435c8591330a849be6a6d64ad82c7294401fa5 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 10:11:16 +0700
Subject: [PATCH 37/84] chore: stage guarded M5 persistence authority migration

---
 tools/fat_m5_authority_patch.py | 45 +++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)
 create mode 100644 tools/fat_m5_authority_patch.py

diff --git a/tools/fat_m5_authority_patch.py b/tools/fat_m5_authority_patch.py
new file mode 100644
index 000000000..e5a974c1f
--- /dev/null
+++ b/tools/fat_m5_authority_patch.py
@@ -0,0 +1,45 @@
+from pathlib import Path
+
+
+def replace_exact(path: Path, old: str, new: str, expected: int = 1) -> None:
+    text = path.read_text(encoding="utf-8")
+    count = text.count(old)
+    if count != expected:
+        raise SystemExit(f"{path}: expected {expected} occurrence(s), found {count}: {old[:80]!r}")
+    path.write_text(text.replace(old, new), encoding="utf-8")
+
+
+persistence = Path("Services/IoTesting/IoTestProjectPersistenceService.cs")
+bootstrap = Path("Services/IoTesting/IoTestWorkspaceBootstrapService.cs")
+
+replace_exact(
+    persistence,
+    """            {\n                LatestComtradeFiles = ied.LatestComtradeFiles,""",
+    """            {\n                // M5: persist the stable Engineering DeviceId when available. Older snapshots\n                // omit this field and continue through the exact IEC identity + endpoint fallback.\n                LiveDeviceId = ied.LiveDeviceId,\n                LatestComtradeFiles = ied.LatestComtradeFiles,""",
+)
+
+replace_exact(
+    persistence,
+    """    {\n        public string LatestComtradeFiles { get; init; } = string.Empty;""",
+    """    {\n        public string LiveDeviceId { get; init; } = string.Empty;\n        public string LatestComtradeFiles { get; init; } = string.Empty;""",
+)
+
+replace_exact(
+    bootstrap,
+    """            if (!currentIedIdentityCounts.TryGetValue(iedKey, out var currentIdentityCount) ||\n                currentIdentityCount != 1 ||\n                !savedIedsByIdentity.TryGetValue(iedKey, out var savedIed))""",
+    """            if (!currentIedIdentityCounts.TryGetValue(iedKey, out var currentIdentityCount) ||\n                currentIdentityCount != 1 ||\n                !savedIedsByIdentity.TryGetValue(iedKey, out var savedIed) ||\n                !IoTestPerIedProgressIdentity.PersistedIedOwnershipMatches(ied, savedIed))""",
+)
+
+replace_exact(
+    bootstrap,
+    """            if (savedIed.ValueKind != JsonValueKind.Object)\n                continue;\n\n            var existingIds = ied.TestPoints""",
+    """            if (savedIed.ValueKind != JsonValueKind.Object ||\n                !IoTestPerIedProgressIdentity.PersistedIedOwnershipMatches(ied, savedIed))\n            {\n                continue;\n            }\n\n            var existingIds = ied.TestPoints""",
+)
+
+replace_exact(
+    bootstrap,
+    """            if (saved.ValueKind != JsonValueKind.Object)\n                continue;\n\n            ied.LatestComtradeFiles""",
+    """            if (saved.ValueKind != JsonValueKind.Object ||\n                !IoTestPerIedProgressIdentity.PersistedIedOwnershipMatches(ied, saved))\n            {\n                continue;\n            }\n\n            ied.LatestComtradeFiles""",
+)
+
+print("M5 persistence authority patch applied")

From 0c3e13d899ba0853db432ca90b7057d46264ecf5 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 10:11:25 +0700
Subject: [PATCH 38/84] chore: run guarded M5 persistence authority migration

---
 .github/workflows/fat-m5-authority-patch.yml | 32 ++++++++++++++++++++
 1 file changed, 32 insertions(+)
 create mode 100644 .github/workflows/fat-m5-authority-patch.yml

diff --git a/.github/workflows/fat-m5-authority-patch.yml b/.github/workflows/fat-m5-authority-patch.yml
new file mode 100644
index 000000000..0635ba6c3
--- /dev/null
+++ b/.github/workflows/fat-m5-authority-patch.yml
@@ -0,0 +1,32 @@
+name: FAT M5 persistence authority patch
+
+on:
+  push:
+    branches:
+      - fix/fat-workstation-convergence
+    paths:
+      - tools/fat_m5_authority_patch.py
+      - .github/workflows/fat-m5-authority-patch.yml
+
+permissions:
+  contents: write
+
+jobs:
+  migrate:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          ref: fix/fat-workstation-convergence
+          fetch-depth: 0
+      - name: Apply guarded M5 authority patch
+        run: python3 tools/fat_m5_authority_patch.py
+      - name: Remove one-shot helpers
+        run: rm tools/fat_m5_authority_patch.py .github/workflows/fat-m5-authority-patch.yml
+      - name: Commit generated source patch
+        run: |
+          git config user.name "github-actions[bot]"
+          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
+          git add Services/IoTesting/IoTestProjectPersistenceService.cs Services/IoTesting/IoTestWorkspaceBootstrapService.cs tools/fat_m5_authority_patch.py .github/workflows/fat-m5-authority-patch.yml
+          git commit -m "M5: bind persisted FAT ownership to Engineering DeviceId"
+          git push origin HEAD:fix/fat-workstation-convergence

From a9d6dd1b0fc112dce39f3ca5e24dcc4a6796ee53 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]"
 <41898282+github-actions[bot]@users.noreply.github.com>
Date: Thu, 10 Sep 2026 03:11:33 +0000
Subject: [PATCH 39/84] M5: bind persisted FAT ownership to Engineering
 DeviceId

---
 .github/workflows/fat-m5-authority-patch.yml  | 32 -------------
 .../IoTestProjectPersistenceService.cs        |  4 ++
 .../IoTestWorkspaceBootstrapService.cs        | 13 ++++--
 tools/fat_m5_authority_patch.py               | 45 -------------------
 4 files changed, 14 insertions(+), 80 deletions(-)
 delete mode 100644 .github/workflows/fat-m5-authority-patch.yml
 delete mode 100644 tools/fat_m5_authority_patch.py

diff --git a/.github/workflows/fat-m5-authority-patch.yml b/.github/workflows/fat-m5-authority-patch.yml
deleted file mode 100644
index 0635ba6c3..000000000
--- a/.github/workflows/fat-m5-authority-patch.yml
+++ /dev/null
@@ -1,32 +0,0 @@
-name: FAT M5 persistence authority patch
-
-on:
-  push:
-    branches:
-      - fix/fat-workstation-convergence
-    paths:
-      - tools/fat_m5_authority_patch.py
-      - .github/workflows/fat-m5-authority-patch.yml
-
-permissions:
-  contents: write
-
-jobs:
-  migrate:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          ref: fix/fat-workstation-convergence
-          fetch-depth: 0
-      - name: Apply guarded M5 authority patch
-        run: python3 tools/fat_m5_authority_patch.py
-      - name: Remove one-shot helpers
-        run: rm tools/fat_m5_authority_patch.py .github/workflows/fat-m5-authority-patch.yml
-      - name: Commit generated source patch
-        run: |
-          git config user.name "github-actions[bot]"
-          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
-          git add Services/IoTesting/IoTestProjectPersistenceService.cs Services/IoTesting/IoTestWorkspaceBootstrapService.cs tools/fat_m5_authority_patch.py .github/workflows/fat-m5-authority-patch.yml
-          git commit -m "M5: bind persisted FAT ownership to Engineering DeviceId"
-          git push origin HEAD:fix/fat-workstation-convergence
diff --git a/Services/IoTesting/IoTestProjectPersistenceService.cs b/Services/IoTesting/IoTestProjectPersistenceService.cs
index 9bfd1e55f..7599f14e0 100644
--- a/Services/IoTesting/IoTestProjectPersistenceService.cs
+++ b/Services/IoTesting/IoTestProjectPersistenceService.cs
@@ -572,6 +572,9 @@ private void SaveFromTimer()
                     ReviewerComment = point.ReviewerComment
                 }).ToList())
             {
+                // M5: persist the stable Engineering DeviceId when available. Older snapshots
+                // omit this field and continue through the exact IEC identity + endpoint fallback.
+                LiveDeviceId = ied.LiveDeviceId,
                 LatestComtradeFiles = ied.LatestComtradeFiles,
                 LatestComtradeRemotePath = ied.LatestComtradeRemotePath,
                 LatestComtradeCompleteness = ied.LatestComtradeCompleteness,
@@ -987,6 +990,7 @@ private sealed record IoTestIedData(
         string Switchgear,
         List<IoTestPointData> TestPoints)
     {
+        public string LiveDeviceId { get; init; } = string.Empty;
         public string LatestComtradeFiles { get; init; } = string.Empty;
         public string LatestComtradeRemotePath { get; init; } = string.Empty;
         public string LatestComtradeCompleteness { get; init; } = string.Empty;
diff --git a/Services/IoTesting/IoTestWorkspaceBootstrapService.cs b/Services/IoTesting/IoTestWorkspaceBootstrapService.cs
index dd5ec3e8d..25f7d3b55 100644
--- a/Services/IoTesting/IoTestWorkspaceBootstrapService.cs
+++ b/Services/IoTesting/IoTestWorkspaceBootstrapService.cs
@@ -250,7 +250,8 @@ private static void ApplySnapshotProgress(IoTestProject project, string snapshot
             var iedKey = IoTestPerIedProgressIdentity.IedKey(ied);
             if (!currentIedIdentityCounts.TryGetValue(iedKey, out var currentIdentityCount) ||
                 currentIdentityCount != 1 ||
-                !savedIedsByIdentity.TryGetValue(iedKey, out var savedIed))
+                !savedIedsByIdentity.TryGetValue(iedKey, out var savedIed) ||
+                !IoTestPerIedProgressIdentity.PersistedIedOwnershipMatches(ied, savedIed))
             {
                 continue;
             }
@@ -445,8 +446,11 @@ private static void RestoreMissingManualWorkspaceRows(
             var savedIed = savedIeds.FirstOrDefault(candidate =>
                 OptionalString(candidate, "iedName", string.Empty).Equals(ied.IedName, StringComparison.OrdinalIgnoreCase) &&
                 OptionalString(candidate, "ipAddress", string.Empty).Equals(ied.IpAddress, StringComparison.OrdinalIgnoreCase));
-            if (savedIed.ValueKind != JsonValueKind.Object)
+            if (savedIed.ValueKind != JsonValueKind.Object ||
+                !IoTestPerIedProgressIdentity.PersistedIedOwnershipMatches(ied, savedIed))
+            {
                 continue;
+            }
 
             var existingIds = ied.TestPoints
                 .Select(point => point.TestPointId)
@@ -543,8 +547,11 @@ private static void RestoreIedLevelEvidence(IoTestProject project, IReadOnlyList
             var saved = savedIeds.FirstOrDefault(candidate =>
                 OptionalString(candidate, "iedName", string.Empty).Equals(ied.IedName, StringComparison.OrdinalIgnoreCase) &&
                 OptionalString(candidate, "ipAddress", string.Empty).Equals(ied.IpAddress, StringComparison.OrdinalIgnoreCase));
-            if (saved.ValueKind != JsonValueKind.Object)
+            if (saved.ValueKind != JsonValueKind.Object ||
+                !IoTestPerIedProgressIdentity.PersistedIedOwnershipMatches(ied, saved))
+            {
                 continue;
+            }
 
             ied.LatestComtradeFiles = OptionalString(saved, "latestComtradeFiles", string.Empty);
             ied.LatestComtradeRemotePath = OptionalString(saved, "latestComtradeRemotePath", string.Empty);
diff --git a/tools/fat_m5_authority_patch.py b/tools/fat_m5_authority_patch.py
deleted file mode 100644
index e5a974c1f..000000000
--- a/tools/fat_m5_authority_patch.py
+++ /dev/null
@@ -1,45 +0,0 @@
-from pathlib import Path
-
-
-def replace_exact(path: Path, old: str, new: str, expected: int = 1) -> None:
-    text = path.read_text(encoding="utf-8")
-    count = text.count(old)
-    if count != expected:
-        raise SystemExit(f"{path}: expected {expected} occurrence(s), found {count}: {old[:80]!r}")
-    path.write_text(text.replace(old, new), encoding="utf-8")
-
-
-persistence = Path("Services/IoTesting/IoTestProjectPersistenceService.cs")
-bootstrap = Path("Services/IoTesting/IoTestWorkspaceBootstrapService.cs")
-
-replace_exact(
-    persistence,
-    """            {\n                LatestComtradeFiles = ied.LatestComtradeFiles,""",
-    """            {\n                // M5: persist the stable Engineering DeviceId when available. Older snapshots\n                // omit this field and continue through the exact IEC identity + endpoint fallback.\n                LiveDeviceId = ied.LiveDeviceId,\n                LatestComtradeFiles = ied.LatestComtradeFiles,""",
-)
-
-replace_exact(
-    persistence,
-    """    {\n        public string LatestComtradeFiles { get; init; } = string.Empty;""",
-    """    {\n        public string LiveDeviceId { get; init; } = string.Empty;\n        public string LatestComtradeFiles { get; init; } = string.Empty;""",
-)
-
-replace_exact(
-    bootstrap,
-    """            if (!currentIedIdentityCounts.TryGetValue(iedKey, out var currentIdentityCount) ||\n                currentIdentityCount != 1 ||\n                !savedIedsByIdentity.TryGetValue(iedKey, out var savedIed))""",
-    """            if (!currentIedIdentityCounts.TryGetValue(iedKey, out var currentIdentityCount) ||\n                currentIdentityCount != 1 ||\n                !savedIedsByIdentity.TryGetValue(iedKey, out var savedIed) ||\n                !IoTestPerIedProgressIdentity.PersistedIedOwnershipMatches(ied, savedIed))""",
-)
-
-replace_exact(
-    bootstrap,
-    """            if (savedIed.ValueKind != JsonValueKind.Object)\n                continue;\n\n            var existingIds = ied.TestPoints""",
-    """            if (savedIed.ValueKind != JsonValueKind.Object ||\n                !IoTestPerIedProgressIdentity.PersistedIedOwnershipMatches(ied, savedIed))\n            {\n                continue;\n            }\n\n            var existingIds = ied.TestPoints""",
-)
-
-replace_exact(
-    bootstrap,
-    """            if (saved.ValueKind != JsonValueKind.Object)\n                continue;\n\n            ied.LatestComtradeFiles""",
-    """            if (saved.ValueKind != JsonValueKind.Object ||\n                !IoTestPerIedProgressIdentity.PersistedIedOwnershipMatches(ied, saved))\n            {\n                continue;\n            }\n\n            ied.LatestComtradeFiles""",
-)
-
-print("M5 persistence authority patch applied")

From 4751621a1e93154a2a6d5fc61bc9ca8056a75881 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 10:13:49 +0700
Subject: [PATCH 40/84] M5: lock DeviceId ownership and read-only
 reconciliation

---
 ...atM5PersistenceAuthorityRegressionTests.cs | 228 ++++++++++++++++++
 1 file changed, 228 insertions(+)
 create mode 100644 tests/ARSAS.Tests/IoFatM5PersistenceAuthorityRegressionTests.cs

diff --git a/tests/ARSAS.Tests/IoFatM5PersistenceAuthorityRegressionTests.cs b/tests/ARSAS.Tests/IoFatM5PersistenceAuthorityRegressionTests.cs
new file mode 100644
index 000000000..401af02fb
--- /dev/null
+++ b/tests/ARSAS.Tests/IoFatM5PersistenceAuthorityRegressionTests.cs
@@ -0,0 +1,228 @@
+using System.Security.Cryptography;
+using System.Text;
+using ArIED61850Tester.Models.IoTesting;
+using ArIED61850Tester.Services.IoTesting;
+using Xunit;
+
+namespace ARSAS.Tests;
+
+public sealed class IoFatM5PersistenceAuthorityRegressionTests
+{
+    [Fact]
+    public async Task Reconcile_DeviceIdMismatch_FailsClosedWithoutRestoringEvidence()
+    {
+        var root = TempDirectory();
+        var sourcePath = await WriteSourceAsync(root, "m5-device-mismatch.xlsx", "m5-device-mismatch-source");
+        var projectsRoot = Path.Combine(root, "projects");
+        var evidenceRoot = Path.Combine(root, "evidence");
+
+        var savedIed = Ied("IED-A", "192.168.90.11", "engineering-device-old");
+        var saved = Project(Hash(sourcePath), savedIed);
+        using (var session = Session(saved, evidenceRoot))
+        {
+            var opened = await IoTestWorkspacePersistence.OpenWorkbookAsync(
+                saved, session, sourcePath, projectsRoot, evidenceRoot);
+            using (opened.Workspace)
+            {
+                CompletePass(opened.Project.Ieds.Single().TestPoints.Single());
+                opened.Workspace.SaveNow();
+            }
+        }
+
+        var evidenceFilesBefore = EvidenceFiles(evidenceRoot);
+        var current = Project(Hash(sourcePath), Ied("IED-A", "192.168.90.11", "engineering-device-new"));
+
+        var reopened = await IoTestWorkspaceBootstrapService.OpenWorkbookAsync(
+            current, sourcePath, projectsRoot, evidenceRoot, Session);
+        using (reopened.Session)
+        using (reopened.Workspace)
+        {
+            Assert.Same(current, reopened.Project);
+            var point = reopened.Project.Ieds.Single().TestPoints.Single();
+            Assert.Equal(IoTestPointState.NotStarted, point.Runtime.State);
+            Assert.Null(point.Runtime.OnEvidence);
+            Assert.Null(point.Runtime.OffEvidence);
+        }
+
+        Assert.Equal(evidenceFilesBefore, EvidenceFiles(evidenceRoot));
+    }
+
+    [Fact]
+    public async Task Reconcile_MatchingDeviceId_RestoresExistingEvidenceWithoutCreatingNewEvidenceFiles()
+    {
+        var root = TempDirectory();
+        var sourcePath = await WriteSourceAsync(root, "m5-device-match.xlsx", "m5-device-match-source");
+        var projectsRoot = Path.Combine(root, "projects");
+        var evidenceRoot = Path.Combine(root, "evidence");
+        const string deviceId = "engineering-device-ied-a";
+
+        var saved = Project(Hash(sourcePath), Ied("IED-A", "192.168.90.21", deviceId));
+        using (var session = Session(saved, evidenceRoot))
+        {
+            var opened = await IoTestWorkspacePersistence.OpenWorkbookAsync(
+                saved, session, sourcePath, projectsRoot, evidenceRoot);
+            using (opened.Workspace)
+            {
+                CompletePass(opened.Project.Ieds.Single().TestPoints.Single());
+                opened.Workspace.SaveNow();
+            }
+        }
+
+        var evidenceFilesBefore = EvidenceFiles(evidenceRoot);
+        var current = Project(Hash(sourcePath), Ied("IED-A", "192.168.90.21", deviceId));
+
+        var reopened = await IoTestWorkspaceBootstrapService.OpenWorkbookAsync(
+            current, sourcePath, projectsRoot, evidenceRoot, Session);
+        using (reopened.Session)
+        using (reopened.Workspace)
+        {
+            Assert.Same(current, reopened.Project);
+            Assert.True(reopened.RestoredProgress);
+            var point = reopened.Project.Ieds.Single().TestPoints.Single();
+            Assert.Equal(IoTestPointState.Passed, point.Runtime.State);
+            Assert.NotNull(point.Runtime.OnEvidence);
+            Assert.NotNull(point.Runtime.OffEvidence);
+        }
+
+        // Background/bootstrap reconciliation may adopt already-persisted evidence into the
+        // fresh Engineering plan, but it is not an evidence-producing operation. Only an
+        // explicit FAT session/capture path is allowed to create journal evidence.
+        Assert.Equal(evidenceFilesBefore, EvidenceFiles(evidenceRoot));
+    }
+
+    [Fact]
+    public async Task Reconcile_LegacyEmptyDeviceId_RemainsCompatibleWithExactIecEndpoint()
+    {
+        var root = TempDirectory();
+        var sourcePath = await WriteSourceAsync(root, "m5-legacy-device.xlsx", "m5-legacy-device-source");
+        var projectsRoot = Path.Combine(root, "projects");
+        var evidenceRoot = Path.Combine(root, "evidence");
+
+        // Empty DeviceId represents historical snapshots created before the M5 authority key.
+        var saved = Project(Hash(sourcePath), Ied("IED-A", "192.168.90.31", deviceId: null));
+        using (var session = Session(saved, evidenceRoot))
+        {
+            var opened = await IoTestWorkspacePersistence.OpenWorkbookAsync(
+                saved, session, sourcePath, projectsRoot, evidenceRoot);
+            using (opened.Workspace)
+            {
+                CompletePass(opened.Project.Ieds.Single().TestPoints.Single());
+                opened.Workspace.SaveNow();
+            }
+        }
+
+        var current = Project(Hash(sourcePath), Ied("IED-A", "192.168.90.31", "engineering-device-now-known"));
+        var reopened = await IoTestWorkspaceBootstrapService.OpenWorkbookAsync(
+            current, sourcePath, projectsRoot, evidenceRoot, Session);
+        using (reopened.Session)
+        using (reopened.Workspace)
+        {
+            var point = reopened.Project.Ieds.Single().TestPoints.Single();
+            Assert.Equal(IoTestPointState.Passed, point.Runtime.State);
+            Assert.NotNull(point.Runtime.OnEvidence);
+            Assert.NotNull(point.Runtime.OffEvidence);
+        }
+    }
+
+    private static IoTestProject Project(string sourceHash, IoTestIedPlan ied)
+    {
+        var project = new IoTestProject
+        {
+            ProjectId = "M5-PERSISTENCE-AUTHORITY",
+            SchemaVersion = "ARSAS-FAT-IO-1.0",
+            ProjectName = "M5 persistence authority",
+            SourceWorkbookName = "m5.xlsx",
+            SourceWorkbookSha256 = sourceHash
+        };
+        project.Ieds.Add(ied);
+        return project;
+    }
+
+    private static IoTestIedPlan Ied(string name, string ip, string? deviceId)
+    {
+        var ied = new IoTestIedPlan
+        {
+            IedName = name,
+            IpAddress = ip,
+            IedRole = "Protection IED",
+            Location = "FAT bench"
+        };
+        if (!string.IsNullOrWhiteSpace(deviceId))
+            ied.ApplyLiveDeviceBinding(deviceId, "Engineering identity bound");
+        ied.TestPoints.Add(Point("TP-001", name, ip, $"{name}LD0/GGIO1.Ind1.stVal"));
+        return ied;
+    }
+
+    private static IoTestPointPlan Point(string id, string iedName, string ip, string objectReference)
+        => new()
+        {
+            TestPointId = id,
+            IedName = iedName,
+            IpAddress = ip,
+            SignalName = "Binary indication",
+            ObjectReference = objectReference,
+            FunctionalConstraint = "ST",
+            ExpectedOnText = "Active",
+            ExpectedOffText = "InActive",
+            ExpectedOnRaw = 1,
+            ExpectedOffRaw = 0,
+            DataType = "SDI",
+            SourceIecReference = objectReference,
+            EventLogSearchReference = objectReference,
+            SignalKind = FatSignalKind.Discrete,
+            CaptureMode = FatCaptureMode.AutomaticTransition,
+            ImportReady = true,
+            BindingStatus = "CID_DATASET_EXACT"
+        };
+
+    private static void CompletePass(IoTestPointPlan point)
+    {
+        var evaluator = new IoTestTransitionEvaluator();
+        evaluator.StartAttempt(point, Observation(false, 1));
+        evaluator.Observe(point, Observation(true, 2));
+        evaluator.Observe(point, Observation(false, 3));
+        Assert.Equal(IoTestPointState.Passed, point.Runtime.State);
+    }
+
+    private static IoTestObservation Observation(bool state, long sequence)
+    {
+        var timestamp = new DateTimeOffset(2026, 9, 10, 3, 0, 0, TimeSpan.Zero).AddMilliseconds(sequence * 100);
+        return new IoTestObservation(
+            state,
+            state ? "True" : "False",
+            timestamp,
+            timestamp.AddMilliseconds(-3),
+            "Good",
+            "BRCB",
+            sequence,
+            1);
+    }
+
+    private static IoTestSessionController Session(IoTestProject project, string evidenceRoot)
+        => new(project, _ => null, action => action(), evidenceRoot);
+
+    private static async Task<string> WriteSourceAsync(string root, string fileName, string content)
+    {
+        var path = Path.Combine(root, fileName);
+        await File.WriteAllBytesAsync(path, Encoding.UTF8.GetBytes(content));
+        return path;
+    }
+
+    private static string[] EvidenceFiles(string evidenceRoot)
+        => !Directory.Exists(evidenceRoot)
+            ? Array.Empty<string>()
+            : Directory.EnumerateFiles(evidenceRoot, "*", SearchOption.AllDirectories)
+                .Select(path => Path.GetRelativePath(evidenceRoot, path))
+                .OrderBy(path => path, StringComparer.Ordinal)
+                .ToArray();
+
+    private static string Hash(string path)
+        => Convert.ToHexString(SHA256.HashData(File.ReadAllBytes(path))).ToLowerInvariant();
+
+    private static string TempDirectory()
+    {
+        var path = Path.Combine(Path.GetTempPath(), "ARSAS.Tests", Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(path);
+        return path;
+    }
+}

From f6ae335a8df44dd2f3a75badc5aa7297b925937c Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 10:18:27 +0700
Subject: [PATCH 41/84] docs: record M3 closure and M5 persistence invariants

---
 docs/FAT_ENGINEERING_WORKSTATION_CONTRACT.md | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/docs/FAT_ENGINEERING_WORKSTATION_CONTRACT.md b/docs/FAT_ENGINEERING_WORKSTATION_CONTRACT.md
index 6ef530e70..7c8619756 100644
--- a/docs/FAT_ENGINEERING_WORKSTATION_CONTRACT.md
+++ b/docs/FAT_ENGINEERING_WORKSTATION_CONTRACT.md
@@ -40,7 +40,15 @@ When a FAT session starts or continues, the capture target is latched to that se
 
 Persisted FAT state is reconciled by stable device/IEC identity. Background reconciliation is read/reconcile-only and must not manufacture new evidence.
 
-A persisted snapshot is evidence input, not authority to replace the fresh Engineering projection. Bootstrap must isolate a canonical prior snapshot before selective reconciliation. If technical IED identity, endpoint/IP, source identity, or point configuration does not match, restore fails closed and the current Engineering project remains authoritative; lower persistence layers must not recover the rejected snapshot wholesale.
+M3 is code/CI closed around this split: selected context remains an operator view/control projection, while evidence actions resolve the owning active IED session. Regression coverage exercises concurrent IED sessions while the selected context changes, and requires independent evidence journals/device routing.
+
+## Persistence authority invariant
+
+A persisted FAT result belongs to an IED only after its IEC technical identity and endpoint match. New M5 snapshots also persist the Engineering `LiveDeviceId`; when both the current Engineering IED and the saved snapshot know a DeviceId, a DeviceId mismatch is a hard fail-closed boundary.
+
+Legacy snapshots without DeviceId may migrate only through the exact IEC identity + endpoint path and the existing evidence-critical point configuration fingerprint. A persistence candidate may contribute prior progress/evidence to the freshly projected Engineering plan, but it must never replace that plan wholesale.
+
+Persistence reconciliation is not an evidence-producing operation. It may adopt already-persisted V1/V2/transition/result state into the matching current IED, but it must not append or manufacture evidence journal records. Production evidence creation remains owned by explicit FAT session/capture operations.
 
 ## Static DataSet authority invariant
 

From 348c5b869dc3da34d73fcdb8bbfd450a7e207088 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 10:21:57 +0700
Subject: [PATCH 42/84] docs: clarify M5 reconciliation is pre-session and
 non-producing

---
 docs/FAT_ENGINEERING_WORKSTATION_CONTRACT.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/docs/FAT_ENGINEERING_WORKSTATION_CONTRACT.md b/docs/FAT_ENGINEERING_WORKSTATION_CONTRACT.md
index 7c8619756..e9b4a1e4c 100644
--- a/docs/FAT_ENGINEERING_WORKSTATION_CONTRACT.md
+++ b/docs/FAT_ENGINEERING_WORKSTATION_CONTRACT.md
@@ -50,6 +50,8 @@ Legacy snapshots without DeviceId may migrate only through the exact IEC identit
 
 Persistence reconciliation is not an evidence-producing operation. It may adopt already-persisted V1/V2/transition/result state into the matching current IED, but it must not append or manufacture evidence journal records. Production evidence creation remains owned by explicit FAT session/capture operations.
 
+The Engineering bootstrap must reconcile the isolated snapshot before creating its production FAT session controller. This ordering is intentional: reconciliation has no active evidence writer to call, then the normal production session/persistence controller is attached after the current Engineering plan has been safely reconciled.
+
 ## Static DataSet authority invariant
 
 Automatic Engineering FAT uses the authoritative static DataSet projection from the already parsed `SclIedWorkspace`.

From 2fe9188cd58ebae1107e337cc5fe4c06c8dd2c66 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 10:27:41 +0700
Subject: [PATCH 43/84] docs: mark M3 code and CI gate complete

---
 docs/FAT_ENGINEERING_WORKSTATION_CONTRACT.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/docs/FAT_ENGINEERING_WORKSTATION_CONTRACT.md b/docs/FAT_ENGINEERING_WORKSTATION_CONTRACT.md
index e9b4a1e4c..0963aba70 100644
--- a/docs/FAT_ENGINEERING_WORKSTATION_CONTRACT.md
+++ b/docs/FAT_ENGINEERING_WORKSTATION_CONTRACT.md
@@ -40,7 +40,7 @@ When a FAT session starts or continues, the capture target is latched to that se
 
 Persisted FAT state is reconciled by stable device/IEC identity. Background reconciliation is read/reconcile-only and must not manufacture new evidence.
 
-M3 is code/CI closed around this split: selected context remains an operator view/control projection, while evidence actions resolve the owning active IED session. Regression coverage exercises concurrent IED sessions while the selected context changes, and requires independent evidence journals/device routing.
+M3 is CODE VERIFIED and CI VERIFIED around this split: selected context remains an operator view/control projection, while evidence actions resolve the owning active IED session. Regression coverage exercises concurrent IED sessions while the selected context changes, and requires independent evidence journals/device routing. FIELD VERIFIED remains intentionally open until physical-IED acceptance.
 
 ## Persistence authority invariant
 

From 178b68d6f33421745aa74f91d584cd3150237e4d Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 11:05:39 +0700
Subject: [PATCH 44/84] M4: add fail-closed production FAT capture target
 adapter

---
 .../IoFatProductionControllerAdapter.cs       | 137 ++++++++++++++++++
 1 file changed, 137 insertions(+)
 create mode 100644 Services/IoTesting/IoFatProductionControllerAdapter.cs

diff --git a/Services/IoTesting/IoFatProductionControllerAdapter.cs b/Services/IoTesting/IoFatProductionControllerAdapter.cs
new file mode 100644
index 000000000..d501009ed
--- /dev/null
+++ b/Services/IoTesting/IoFatProductionControllerAdapter.cs
@@ -0,0 +1,137 @@
+using ArIED61850Tester.Models.IoTesting;
+
+namespace ArIED61850Tester.Services.IoTesting;
+
+/// <summary>
+/// M4 transaction boundary between Engineering's mutable view context and the existing
+/// production FAT evidence engine. It freezes the operator-selected IED and exact capture
+/// scope before asynchronous connection preparation, then revalidates that lease before
+/// delegating to <see cref="IoTestMultiSessionCoordinator.Start(IoTestIedPlan?, IReadOnlyCollection{IoTestPointPlan}?)"/>.
+///
+/// This class deliberately does not parse SCL, discover/connect an IED, evaluate transitions,
+/// or write evidence. Those authorities remain with Engineering and IoTestSessionController.
+/// </summary>
+public static class IoFatProductionControllerAdapter
+{
+    public static IoFatCaptureTargetLease LatchStartTarget(
+        IoTestProject project,
+        IoTestIedPlan? ied)
+    {
+        ArgumentNullException.ThrowIfNull(project);
+        if (ied == null)
+            throw new InvalidOperationException("Select an imported IED first.");
+        if (!project.Ieds.Contains(ied))
+            throw new InvalidOperationException("The selected IED is no longer part of this FAT project.");
+
+        var preflight = IoTestSessionPreflight.Validate(ied);
+        if (!preflight.Succeeded)
+            throw new InvalidOperationException(preflight.Message);
+
+        var points = ied.TestPoints
+            .Where(point =>
+                point.WorkspaceSelected &&
+                point.IsIncludedInFat &&
+                point.TestEnabled &&
+                point.ImportReady)
+            .Distinct()
+            .Select(point => new IoFatCapturePointLease(
+                point,
+                IoTestPerIedProgressIdentity.PointConfigurationFingerprint(point)))
+            .ToArray();
+        if (points.Length == 0)
+        {
+            throw new InvalidOperationException(
+                "No import-ready operator-selected signal is available in the requested FAT capture scope.");
+        }
+
+        return new IoFatCaptureTargetLease(
+            ied,
+            IoTestPerIedProgressIdentity.IedKey(ied),
+            ied.LiveDeviceId?.Trim() ?? string.Empty,
+            points);
+    }
+
+    public static IoTestSessionActionResult StartLatched(
+        IoTestProject project,
+        IoTestMultiSessionCoordinator sessions,
+        IoFatCaptureTargetLease lease)
+    {
+        ArgumentNullException.ThrowIfNull(project);
+        ArgumentNullException.ThrowIfNull(sessions);
+        ArgumentNullException.ThrowIfNull(lease);
+
+        var validation = ValidateLease(project, lease);
+        if (!validation.Succeeded)
+            return validation;
+
+        // The existing production controller remains the only evidence writer. Passing the
+        // frozen scope prevents an async Engineering prepare from silently broadening or
+        // redirecting the session when Explorer selection/workspace membership changes.
+        return sessions.Start(lease.Ied, lease.CaptureScope);
+    }
+
+    public static IoTestSessionActionResult ValidateLease(
+        IoTestProject project,
+        IoFatCaptureTargetLease lease)
+    {
+        ArgumentNullException.ThrowIfNull(project);
+        ArgumentNullException.ThrowIfNull(lease);
+
+        if (!project.Ieds.Contains(lease.Ied))
+            return IoTestSessionActionResult.Failure("The latched FAT IED left the project while connection preparation was running. No evidence session was started.");
+
+        var currentIedIdentity = IoTestPerIedProgressIdentity.IedKey(lease.Ied);
+        if (!currentIedIdentity.Equals(lease.IedIdentity, StringComparison.OrdinalIgnoreCase))
+        {
+            return IoTestSessionActionResult.Failure(
+                "The latched IEC IED identity or endpoint changed during connection preparation. No evidence session was started.");
+        }
+
+        var currentDeviceId = lease.Ied.LiveDeviceId?.Trim() ?? string.Empty;
+        if (!string.IsNullOrWhiteSpace(lease.DeviceId) &&
+            !currentDeviceId.Equals(lease.DeviceId, StringComparison.OrdinalIgnoreCase))
+        {
+            return IoTestSessionActionResult.Failure(
+                "The Engineering DeviceId bound to the latched FAT IED changed during connection preparation. No evidence session was started.");
+        }
+
+        foreach (var pointLease in lease.Points)
+        {
+            var point = pointLease.Point;
+            if (!lease.Ied.TestPoints.Contains(point))
+            {
+                return IoTestSessionActionResult.Failure(
+                    "A latched FAT row left its owning IED during connection preparation. No evidence session was started.");
+            }
+            if (!point.WorkspaceSelected || !point.IsIncludedInFat || !point.TestEnabled || !point.ImportReady)
+            {
+                return IoTestSessionActionResult.Failure(
+                    $"The latched FAT row '{point.SignalName}' changed eligibility during connection preparation. Review the scope and press Start FAT again.");
+            }
+
+            var fingerprint = IoTestPerIedProgressIdentity.PointConfigurationFingerprint(point);
+            if (!fingerprint.Equals(pointLease.ConfigurationFingerprint, StringComparison.OrdinalIgnoreCase))
+            {
+                return IoTestSessionActionResult.Failure(
+                    $"The IEC/evidence configuration of latched FAT row '{point.SignalName}' changed during connection preparation. No evidence session was started.");
+            }
+        }
+
+        return IoTestSessionActionResult.Success(
+            $"Latched FAT target verified: {lease.Ied.IedName} · {lease.Points.Count} point(s).");
+    }
+}
+
+public sealed record IoFatCapturePointLease(
+    IoTestPointPlan Point,
+    string ConfigurationFingerprint);
+
+public sealed record IoFatCaptureTargetLease(
+    IoTestIedPlan Ied,
+    string IedIdentity,
+    string DeviceId,
+    IReadOnlyList<IoFatCapturePointLease> Points)
+{
+    public IReadOnlyList<IoTestPointPlan> CaptureScope { get; } =
+        Points.Select(point => point.Point).ToArray();
+}

From 9ba4be80a8e80fdacb1279febf1fa11de350ee68 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 11:06:14 +0700
Subject: [PATCH 45/84] chore: stage guarded M4 production adapter wiring

---
 tools/fat_m4_production_adapter_patch.py | 204 +++++++++++++++++++++++
 1 file changed, 204 insertions(+)
 create mode 100644 tools/fat_m4_production_adapter_patch.py

diff --git a/tools/fat_m4_production_adapter_patch.py b/tools/fat_m4_production_adapter_patch.py
new file mode 100644
index 000000000..5ff704611
--- /dev/null
+++ b/tools/fat_m4_production_adapter_patch.py
@@ -0,0 +1,204 @@
+from pathlib import Path
+
+
+def replace_exact(path: Path, old: str, new: str, expected: int = 1) -> None:
+    text = path.read_text(encoding="utf-8")
+    count = text.count(old)
+    if count != expected:
+        raise SystemExit(f"{path}: expected {expected} occurrence(s), found {count}: {old[:100]!r}")
+    path.write_text(text.replace(old, new), encoding="utf-8")
+
+
+coordinator = Path("Services/IoTesting/IoTestMultiSessionCoordinator.cs")
+window = Path("IoListTestingWindow.xaml.cs")
+
+replace_exact(
+    coordinator,
+    '''    public IoTestSessionActionResult Pause(string reason = "Paused by operator")
+        => SelectedAction(
+            controller => controller.Pause(reason),
+            "No FAT evidence session is active for the selected IED.");
+
+    public IoTestSessionActionResult Resume()
+        => SelectedAction(
+            controller => controller.Resume(),
+            "No paused or interrupted FAT evidence session belongs to the selected IED.");
+
+    public IoTestSessionActionResult Stop(string reason = "Stopped by operator")
+        => SelectedAction(
+            controller => controller.Stop(reason),
+            "No FAT evidence session is active for the selected IED.");
+''',
+    '''    public IoTestSessionActionResult Pause(string reason = "Paused by operator")
+        => SelectedAction(
+            controller => controller.Pause(reason),
+            "No FAT evidence session is active for the selected IED.");
+
+    public IoTestSessionActionResult Pause(IoTestIedPlan? ied, string reason = "Paused by operator")
+        => TargetAction(
+            ied,
+            controller => controller.Pause(reason),
+            "No FAT evidence session is active for the latched IED.");
+
+    public IoTestSessionActionResult Resume()
+        => SelectedAction(
+            controller => controller.Resume(),
+            "No paused or interrupted FAT evidence session belongs to the selected IED.");
+
+    public IoTestSessionActionResult Resume(IoTestIedPlan? ied)
+        => TargetAction(
+            ied,
+            controller => controller.Resume(),
+            "No paused or interrupted FAT evidence session belongs to the latched IED.");
+
+    public IoTestSessionActionResult Stop(string reason = "Stopped by operator")
+        => SelectedAction(
+            controller => controller.Stop(reason),
+            "No FAT evidence session is active for the selected IED.");
+
+    public IoTestSessionActionResult Stop(IoTestIedPlan? ied, string reason = "Stopped by operator")
+        => TargetAction(
+            ied,
+            controller => controller.Stop(reason),
+            "No FAT evidence session is active for the latched IED.");
+''')
+
+replace_exact(
+    coordinator,
+    '''    private IoTestSessionActionResult SelectedAction(
+        Func<IoTestSessionController, IoTestSessionActionResult> action,
+        string missingMessage)
+''',
+    '''    private IoTestSessionActionResult TargetAction(
+        IoTestIedPlan? ied,
+        Func<IoTestSessionController, IoTestSessionActionResult> action,
+        string missingMessage)
+    {
+        ThrowIfDisposed();
+        if (ied == null)
+            return IoTestSessionActionResult.Failure(missingMessage);
+
+        IoTestSessionController? controller;
+        lock (_sync)
+            _controllers.TryGetValue(ied, out controller);
+        if (controller == null)
+            return IoTestSessionActionResult.Failure(missingMessage);
+
+        var result = action(controller);
+        RaiseProjectionProperties();
+        return result;
+    }
+
+    private IoTestSessionActionResult SelectedAction(
+        Func<IoTestSessionController, IoTestSessionActionResult> action,
+        string missingMessage)
+''')
+
+replace_exact(
+    window,
+    '''        // Capture target latch: keep this local IED for the complete async prepare +
+        // Start transaction even if the global Engineering Explorer changes selection.
+        var selectedIed = SelectedIed;
+        if (selectedIed?.IsPreparing == true)
+            return;
+
+        var preflight = IoTestSessionPreflight.Validate(selectedIed);
+        if (!preflight.Succeeded)
+        {
+            ShowActionResult(preflight, "FAT session scope is not ready");
+            return;
+        }
+
+        PreparationStatusText = $"Connecting {selectedIed!.IedName} · {selectedIed.IpAddress}:102";
+''',
+    '''        // M4 freezes both the IED owner and exact evidence scope before any asynchronous
+        // Engineering preparation. Explorer navigation may continue, but it cannot redirect
+        // this transaction or silently widen the production capture scope.
+        var requestedIed = SelectedIed;
+        if (requestedIed?.IsPreparing == true)
+            return;
+
+        IoFatCaptureTargetLease captureLease;
+        try
+        {
+            captureLease = IoFatProductionControllerAdapter.LatchStartTarget(Project, requestedIed);
+        }
+        catch (InvalidOperationException ex)
+        {
+            ShowActionResult(
+                IoTestSessionActionResult.Failure(ex.Message),
+                "FAT session scope is not ready");
+            return;
+        }
+
+        var selectedIed = captureLease.Ied;
+        PreparationStatusText = $"Connecting {selectedIed.IedName} · {selectedIed.IpAddress}:102";
+''')
+
+replace_exact(
+    window,
+    '''            var result = Session.Start(selectedIed);
+''',
+    '''            // Revalidate the frozen identity/configuration only after Engineering has
+            // completed connection preparation. The adapter delegates to the unchanged
+            // production session controller, which remains the sole evidence writer.
+            var result = IoFatProductionControllerAdapter.StartLatched(Project, Session, captureLease);
+''')
+
+replace_exact(
+    window,
+    '''    private void PauseSession_Click(object sender, RoutedEventArgs e)
+    {
+        var result = Session.Pause();
+        ShowActionResult(result, "FAT session could not pause");
+        if (result.Succeeded)
+            Storage?.SaveNow();
+    }
+
+    private void ResumeSession_Click(object sender, RoutedEventArgs e)
+    {
+        var result = Session.Resume();
+        ShowActionResult(result, "FAT session could not resume");
+        if (result.Succeeded)
+            Storage?.ScheduleSave();
+    }
+
+    private void StopSession_Click(object sender, RoutedEventArgs e)
+    {
+        var result = Session.Stop();
+        ShowActionResult(result, "FAT session could not stop");
+        if (result.Succeeded)
+            Storage?.SaveNow();
+    }
+''',
+    '''    private void PauseSession_Click(object sender, RoutedEventArgs e)
+    {
+        var targetIed = SelectedIed;
+        var result = Session.Pause(targetIed);
+        ShowActionResult(result, "FAT session could not pause");
+        if (result.Succeeded)
+            Storage?.SaveNow();
+    }
+
+    private void ResumeSession_Click(object sender, RoutedEventArgs e)
+    {
+        // Continue is explicitly IED-targeted. A later Explorer change cannot make the
+        // production controller rebind this active evidence session to another device.
+        var targetIed = SelectedIed;
+        var result = Session.Resume(targetIed);
+        ShowActionResult(result, "FAT session could not resume");
+        if (result.Succeeded)
+            Storage?.ScheduleSave();
+    }
+
+    private void StopSession_Click(object sender, RoutedEventArgs e)
+    {
+        var targetIed = SelectedIed;
+        var result = Session.Stop(targetIed);
+        ShowActionResult(result, "FAT session could not stop");
+        if (result.Succeeded)
+            Storage?.SaveNow();
+    }
+''')
+
+print("M4 production adapter wiring applied")

From 9dcc6db64df3fca553cedcacf9350c26bbda87bd Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 11:06:29 +0700
Subject: [PATCH 46/84] chore: run guarded M4 production adapter wiring

---
 .../fat-m4-production-adapter-patch.yml       | 32 +++++++++++++++++++
 1 file changed, 32 insertions(+)
 create mode 100644 .github/workflows/fat-m4-production-adapter-patch.yml

diff --git a/.github/workflows/fat-m4-production-adapter-patch.yml b/.github/workflows/fat-m4-production-adapter-patch.yml
new file mode 100644
index 000000000..72a6571c2
--- /dev/null
+++ b/.github/workflows/fat-m4-production-adapter-patch.yml
@@ -0,0 +1,32 @@
+name: FAT M4 production adapter patch
+
+on:
+  push:
+    branches:
+      - fix/fat-workstation-convergence
+    paths:
+      - tools/fat_m4_production_adapter_patch.py
+      - .github/workflows/fat-m4-production-adapter-patch.yml
+
+permissions:
+  contents: write
+
+jobs:
+  migrate:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          ref: fix/fat-workstation-convergence
+          fetch-depth: 0
+      - name: Apply guarded M4 production adapter wiring
+        run: python3 tools/fat_m4_production_adapter_patch.py
+      - name: Remove one-shot helpers
+        run: rm tools/fat_m4_production_adapter_patch.py .github/workflows/fat-m4-production-adapter-patch.yml
+      - name: Commit generated source patch
+        run: |
+          git config user.name "github-actions[bot]"
+          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
+          git add Services/IoTesting/IoTestMultiSessionCoordinator.cs IoListTestingWindow.xaml.cs tools/fat_m4_production_adapter_patch.py .github/workflows/fat-m4-production-adapter-patch.yml
+          git commit -m "M4: latch production FAT target across prepare and continue"
+          git push origin HEAD:fix/fat-workstation-convergence

From 2e376288751b625d015f661859b765f147263470 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 11:07:55 +0700
Subject: [PATCH 47/84] M4: add production capture lease and continue isolation
 regressions

---
 ...ductionControllerAdapterRegressionTests.cs | 236 ++++++++++++++++++
 1 file changed, 236 insertions(+)
 create mode 100644 tests/ARSAS.Tests/IoFatM4ProductionControllerAdapterRegressionTests.cs

diff --git a/tests/ARSAS.Tests/IoFatM4ProductionControllerAdapterRegressionTests.cs b/tests/ARSAS.Tests/IoFatM4ProductionControllerAdapterRegressionTests.cs
new file mode 100644
index 000000000..87888f7f6
--- /dev/null
+++ b/tests/ARSAS.Tests/IoFatM4ProductionControllerAdapterRegressionTests.cs
@@ -0,0 +1,236 @@
+using ArIED61850Tester.Models;
+using ArIED61850Tester.Models.IoTesting;
+using ArIED61850Tester.Services.IoTesting;
+
+namespace ARSAS.Tests;
+
+public sealed class IoFatM4ProductionControllerAdapterRegressionTests
+{
+    [Fact]
+    public void LatchedStart_DoesNotFollowExplorerSelection_AndKeepsFrozenScope()
+    {
+        var fixture = CreateFixture();
+        fixture.PointA2.WorkspaceSelected = false;
+        new IoTestLiveBindingService().Bind(fixture.Project, fixture.Devices);
+
+        using var primary = NewController(fixture.Project, fixture.Devices, fixture.Root);
+        using var sessions = new IoTestMultiSessionCoordinator(fixture.Project, primary);
+        sessions.SelectContext(fixture.IedA);
+
+        var lease = IoFatProductionControllerAdapter.LatchStartTarget(fixture.Project, fixture.IedA);
+        Assert.Single(lease.Points);
+        Assert.Same(fixture.PointA1, lease.Points[0].Point);
+
+        // Simulate changes that can occur while Engineering connection preparation awaits:
+        // the global Explorer now views B and a second row becomes selected. Neither may
+        // redirect or widen the already-latched production evidence transaction.
+        sessions.SelectContext(fixture.IedB);
+        fixture.PointA2.WorkspaceSelected = true;
+
+        var start = IoFatProductionControllerAdapter.StartLatched(fixture.Project, sessions, lease);
+
+        Assert.True(start.Succeeded, start.Message);
+        Assert.Same(fixture.IedB, sessions.SelectedIed);
+        Assert.True(sessions.IsIedSessionActive(fixture.IedA));
+        Assert.False(sessions.IsIedSessionActive(fixture.IedB));
+        Assert.Contains(" / 1 complete", primary.ProgressText, StringComparison.Ordinal);
+
+        Assert.True(sessions.Stop(fixture.IedA, "test cleanup").Succeeded);
+    }
+
+    [Fact]
+    public void LatchedStart_FailsClosed_WhenEngineeringDeviceIdDriftsBeforeStart()
+    {
+        var fixture = CreateFixture();
+        new IoTestLiveBindingService().Bind(fixture.Project, fixture.Devices);
+
+        using var primary = NewController(fixture.Project, fixture.Devices, fixture.Root);
+        using var sessions = new IoTestMultiSessionCoordinator(fixture.Project, primary);
+        var lease = IoFatProductionControllerAdapter.LatchStartTarget(fixture.Project, fixture.IedA);
+        Assert.Equal("device-a", lease.DeviceId, ignoreCase: true);
+
+        fixture.IedA.ApplyLiveDeviceBinding(
+            "device-b",
+            "simulated Engineering binding drift",
+            isConnected: true,
+            isMonitoring: true);
+
+        var start = IoFatProductionControllerAdapter.StartLatched(fixture.Project, sessions, lease);
+
+        Assert.False(start.Succeeded);
+        Assert.Contains("DeviceId", start.Message, StringComparison.OrdinalIgnoreCase);
+        Assert.False(sessions.HasActiveSessions);
+        Assert.Empty(Directory.GetFiles(fixture.Root, "*.evidence.jsonl", SearchOption.AllDirectories));
+    }
+
+    [Fact]
+    public void LatchedStart_FailsClosed_WhenFrozenRowEligibilityChanges()
+    {
+        var fixture = CreateFixture();
+        new IoTestLiveBindingService().Bind(fixture.Project, fixture.Devices);
+
+        using var primary = NewController(fixture.Project, fixture.Devices, fixture.Root);
+        using var sessions = new IoTestMultiSessionCoordinator(fixture.Project, primary);
+        var lease = IoFatProductionControllerAdapter.LatchStartTarget(fixture.Project, fixture.IedA);
+
+        fixture.PointA1.WorkspaceSelected = false;
+        var start = IoFatProductionControllerAdapter.StartLatched(fixture.Project, sessions, lease);
+
+        Assert.False(start.Succeeded);
+        Assert.Contains("eligibility", start.Message, StringComparison.OrdinalIgnoreCase);
+        Assert.False(sessions.HasActiveSessions);
+        Assert.Empty(Directory.GetFiles(fixture.Root, "*.evidence.jsonl", SearchOption.AllDirectories));
+    }
+
+    [Fact]
+    public void ContinuePauseAndStop_UseExplicitIedOwner_NotCurrentExplorerProjection()
+    {
+        var fixture = CreateFixture();
+        new IoTestLiveBindingService().Bind(fixture.Project, fixture.Devices);
+
+        using var primary = NewController(fixture.Project, fixture.Devices, fixture.Root);
+        using var sessions = new IoTestMultiSessionCoordinator(fixture.Project, primary);
+        sessions.SelectContext(fixture.IedA);
+        var lease = IoFatProductionControllerAdapter.LatchStartTarget(fixture.Project, fixture.IedA);
+        Assert.True(IoFatProductionControllerAdapter.StartLatched(fixture.Project, sessions, lease).Succeeded);
+
+        Assert.True(sessions.Pause(fixture.IedA, "pause A").Succeeded);
+        sessions.SelectContext(fixture.IedB);
+
+        // Continue A while B is the viewed IED. The selected projection must remain B,
+        // while the active production controller continues its already-owned A session.
+        var resume = sessions.Resume(fixture.IedA);
+        Assert.True(resume.Succeeded, resume.Message);
+        Assert.Same(fixture.IedB, sessions.SelectedIed);
+        Assert.True(sessions.IsIedSessionActive(fixture.IedA));
+        Assert.False(sessions.IsIedSessionActive(fixture.IedB));
+
+        var stop = sessions.Stop(fixture.IedA, "stop A");
+        Assert.True(stop.Succeeded, stop.Message);
+        Assert.False(sessions.HasActiveSessions);
+        Assert.Same(fixture.IedB, sessions.SelectedIed);
+    }
+
+    private static Fixture CreateFixture()
+    {
+        var pointA1 = Point("A-1", "IED_A", "192.168.81.10", "IED_ALD0/GGIO1.Ind1.stVal");
+        var pointA2 = Point("A-2", "IED_A", "192.168.81.10", "IED_ALD0/GGIO1.Ind2.stVal");
+        var pointB = Point("B-1", "IED_B", "192.168.81.11", "IED_BLD0/GGIO1.Ind1.stVal");
+        var iedA = Ied("IED_A", "192.168.81.10", pointA1, pointA2);
+        var iedB = Ied("IED_B", "192.168.81.11", pointB);
+        var project = new IoTestProject
+        {
+            ProjectId = "M4-CAPTURE-LEASE",
+            SchemaVersion = "ARSAS-FAT-IO-1.0",
+            ProjectName = "M4 Production Adapter",
+            SourceWorkbookName = "M4.xlsx",
+            SourceWorkbookSha256 = new string('b', 64),
+            Ieds = { iedA, iedB }
+        };
+        project.InitializeRuntimeNotifications();
+
+        var deviceA = Device("device-a", iedA, pointA1, pointA2);
+        var deviceB = Device("device-b", iedB, pointB);
+        var devices = new[] { deviceA, deviceB };
+        var root = Path.Combine(Path.GetTempPath(), "ARSAS.Tests", "M4", Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(root);
+        return new Fixture(project, iedA, iedB, pointA1, pointA2, pointB, devices, root);
+    }
+
+    private static IoTestPointPlan Point(string id, string iedName, string ipAddress, string reference) => new()
+    {
+        TestPointId = id,
+        IedName = iedName,
+        IpAddress = ipAddress,
+        SignalName = id,
+        ObjectReference = reference,
+        FunctionalConstraint = "ST",
+        ExpectedOnText = "ON",
+        ExpectedOffText = "OFF",
+        ExpectedOnRaw = 1,
+        ExpectedOffRaw = 0,
+        DataType = "BOOLEAN",
+        LogicalDevice = iedName + "LD0",
+        LogicalNode = "GGIO1",
+        DataObject = "Ind",
+        DataAttribute = "stVal",
+        SourceIecReference = reference,
+        EventLogSearchReference = reference,
+        ReportDisplayReference = reference + " [ST]",
+        BindingStatus = "CID_DATASET_EXACT",
+        TestEnabled = true,
+        ImportReady = true
+    };
+
+    private static IoTestIedPlan Ied(string name, string ipAddress, params IoTestPointPlan[] points)
+    {
+        var ied = new IoTestIedPlan
+        {
+            IedName = name,
+            IpAddress = ipAddress,
+            IedRole = "Protection IED"
+        };
+        ied.TestPoints.AddRange(points);
+        return ied;
+    }
+
+    private static Iec61850MonitorDevice Device(
+        string deviceId,
+        IoTestIedPlan ied,
+        params IoTestPointPlan[] points)
+    {
+        var device = new Iec61850MonitorDevice
+        {
+            DeviceId = deviceId,
+            Name = ied.IedName,
+            SclIedName = ied.IedName,
+            IpAddress = ied.IpAddress,
+            Port = 102,
+            IsConnected = true,
+            IsMonitoring = true,
+            Status = "Monitoring"
+        };
+
+        foreach (var point in points)
+        {
+            device.Points.Add(new Iec61850MonitorPoint
+            {
+                DeviceId = deviceId,
+                DeviceName = ied.IedName,
+                IpAddress = ied.IpAddress,
+                SignalName = point.SignalName,
+                IecReference = point.ObjectReference,
+                FunctionalConstraint = "ST",
+                Value = "False",
+                Quality = "Good",
+                DeviceTimestamp = "2026-09-10T04:00:00.000Z",
+                SourceMode = "BRCB",
+                Sequence = 0,
+                Status = "Live"
+            });
+        }
+        return device;
+    }
+
+    private static IoTestSessionController NewController(
+        IoTestProject project,
+        IReadOnlyCollection<Iec61850MonitorDevice> devices,
+        string root) => new(
+            project,
+            key => devices.FirstOrDefault(device =>
+                key.Equals(device.DeviceId, StringComparison.OrdinalIgnoreCase) ||
+                key.Equals(device.Name, StringComparison.OrdinalIgnoreCase) ||
+                key.Equals(device.IpAddress, StringComparison.OrdinalIgnoreCase)),
+            action => action(),
+            root);
+
+    private sealed record Fixture(
+        IoTestProject Project,
+        IoTestIedPlan IedA,
+        IoTestIedPlan IedB,
+        IoTestPointPlan PointA1,
+        IoTestPointPlan PointA2,
+        IoTestPointPlan PointB,
+        IReadOnlyCollection<Iec61850MonitorDevice> Devices,
+        string Root);
+}

From 59d1d10404abb48904084ff679268bec2b8ab279 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]"
 <41898282+github-actions[bot]@users.noreply.github.com>
Date: Thu, 10 Sep 2026 04:17:31 +0000
Subject: [PATCH 48/84] M4: latch production FAT target across prepare and
 continue

---
 .../fat-m4-production-adapter-patch.yml       |  32 ---
 IoListTestingWindow.xaml.cs                   |  40 ++--
 .../IoTestMultiSessionCoordinator.cs          |  38 ++++
 tools/fat_m4_production_adapter_patch.py      | 204 ------------------
 4 files changed, 66 insertions(+), 248 deletions(-)
 delete mode 100644 .github/workflows/fat-m4-production-adapter-patch.yml
 delete mode 100644 tools/fat_m4_production_adapter_patch.py

diff --git a/.github/workflows/fat-m4-production-adapter-patch.yml b/.github/workflows/fat-m4-production-adapter-patch.yml
deleted file mode 100644
index 72a6571c2..000000000
--- a/.github/workflows/fat-m4-production-adapter-patch.yml
+++ /dev/null
@@ -1,32 +0,0 @@
-name: FAT M4 production adapter patch
-
-on:
-  push:
-    branches:
-      - fix/fat-workstation-convergence
-    paths:
-      - tools/fat_m4_production_adapter_patch.py
-      - .github/workflows/fat-m4-production-adapter-patch.yml
-
-permissions:
-  contents: write
-
-jobs:
-  migrate:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          ref: fix/fat-workstation-convergence
-          fetch-depth: 0
-      - name: Apply guarded M4 production adapter wiring
-        run: python3 tools/fat_m4_production_adapter_patch.py
-      - name: Remove one-shot helpers
-        run: rm tools/fat_m4_production_adapter_patch.py .github/workflows/fat-m4-production-adapter-patch.yml
-      - name: Commit generated source patch
-        run: |
-          git config user.name "github-actions[bot]"
-          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
-          git add Services/IoTesting/IoTestMultiSessionCoordinator.cs IoListTestingWindow.xaml.cs tools/fat_m4_production_adapter_patch.py .github/workflows/fat-m4-production-adapter-patch.yml
-          git commit -m "M4: latch production FAT target across prepare and continue"
-          git push origin HEAD:fix/fat-workstation-convergence
diff --git a/IoListTestingWindow.xaml.cs b/IoListTestingWindow.xaml.cs
index 3d23341be..c1ec2bcea 100644
--- a/IoListTestingWindow.xaml.cs
+++ b/IoListTestingWindow.xaml.cs
@@ -119,20 +119,28 @@ private void SetAddingFatIeds(bool value)
 
     private async void StartSession_Click(object sender, RoutedEventArgs e)
     {
-        // Capture target latch: keep this local IED for the complete async prepare +
-        // Start transaction even if the global Engineering Explorer changes selection.
-        var selectedIed = SelectedIed;
-        if (selectedIed?.IsPreparing == true)
+        // M4 freezes both the IED owner and exact evidence scope before any asynchronous
+        // Engineering preparation. Explorer navigation may continue, but it cannot redirect
+        // this transaction or silently widen the production capture scope.
+        var requestedIed = SelectedIed;
+        if (requestedIed?.IsPreparing == true)
             return;
 
-        var preflight = IoTestSessionPreflight.Validate(selectedIed);
-        if (!preflight.Succeeded)
+        IoFatCaptureTargetLease captureLease;
+        try
+        {
+            captureLease = IoFatProductionControllerAdapter.LatchStartTarget(Project, requestedIed);
+        }
+        catch (InvalidOperationException ex)
         {
-            ShowActionResult(preflight, "FAT session scope is not ready");
+            ShowActionResult(
+                IoTestSessionActionResult.Failure(ex.Message),
+                "FAT session scope is not ready");
             return;
         }
 
-        PreparationStatusText = $"Connecting {selectedIed!.IedName} · {selectedIed.IpAddress}:102";
+        var selectedIed = captureLease.Ied;
+        PreparationStatusText = $"Connecting {selectedIed.IedName} · {selectedIed.IpAddress}:102";
         RaisePreparationProperties();
         try
         {
@@ -157,7 +165,10 @@ private async void StartSession_Click(object sender, RoutedEventArgs e)
                 }
             }
 
-            var result = Session.Start(selectedIed);
+            // Revalidate the frozen identity/configuration only after Engineering has
+            // completed connection preparation. The adapter delegates to the unchanged
+            // production session controller, which remains the sole evidence writer.
+            var result = IoFatProductionControllerAdapter.StartLatched(Project, Session, captureLease);
             ShowActionResult(result, "FAT evidence session could not start");
             RaiseStatusProperties();
             if (result.Succeeded)
@@ -189,7 +200,8 @@ private async void StartSession_Click(object sender, RoutedEventArgs e)
 
     private void PauseSession_Click(object sender, RoutedEventArgs e)
     {
-        var result = Session.Pause();
+        var targetIed = SelectedIed;
+        var result = Session.Pause(targetIed);
         ShowActionResult(result, "FAT session could not pause");
         if (result.Succeeded)
             Storage?.SaveNow();
@@ -197,7 +209,10 @@ private void PauseSession_Click(object sender, RoutedEventArgs e)
 
     private void ResumeSession_Click(object sender, RoutedEventArgs e)
     {
-        var result = Session.Resume();
+        // Continue is explicitly IED-targeted. A later Explorer change cannot make the
+        // production controller rebind this active evidence session to another device.
+        var targetIed = SelectedIed;
+        var result = Session.Resume(targetIed);
         ShowActionResult(result, "FAT session could not resume");
         if (result.Succeeded)
             Storage?.ScheduleSave();
@@ -205,7 +220,8 @@ private void ResumeSession_Click(object sender, RoutedEventArgs e)
 
     private void StopSession_Click(object sender, RoutedEventArgs e)
     {
-        var result = Session.Stop();
+        var targetIed = SelectedIed;
+        var result = Session.Stop(targetIed);
         ShowActionResult(result, "FAT session could not stop");
         if (result.Succeeded)
             Storage?.SaveNow();
diff --git a/Services/IoTesting/IoTestMultiSessionCoordinator.cs b/Services/IoTesting/IoTestMultiSessionCoordinator.cs
index e80146dd7..9c1d6236d 100644
--- a/Services/IoTesting/IoTestMultiSessionCoordinator.cs
+++ b/Services/IoTesting/IoTestMultiSessionCoordinator.cs
@@ -156,16 +156,34 @@ public IoTestSessionActionResult Pause(string reason = "Paused by operator")
             controller => controller.Pause(reason),
             "No FAT evidence session is active for the selected IED.");
 
+    public IoTestSessionActionResult Pause(IoTestIedPlan? ied, string reason = "Paused by operator")
+        => TargetAction(
+            ied,
+            controller => controller.Pause(reason),
+            "No FAT evidence session is active for the latched IED.");
+
     public IoTestSessionActionResult Resume()
         => SelectedAction(
             controller => controller.Resume(),
             "No paused or interrupted FAT evidence session belongs to the selected IED.");
 
+    public IoTestSessionActionResult Resume(IoTestIedPlan? ied)
+        => TargetAction(
+            ied,
+            controller => controller.Resume(),
+            "No paused or interrupted FAT evidence session belongs to the latched IED.");
+
     public IoTestSessionActionResult Stop(string reason = "Stopped by operator")
         => SelectedAction(
             controller => controller.Stop(reason),
             "No FAT evidence session is active for the selected IED.");
 
+    public IoTestSessionActionResult Stop(IoTestIedPlan? ied, string reason = "Stopped by operator")
+        => TargetAction(
+            ied,
+            controller => controller.Stop(reason),
+            "No FAT evidence session is active for the latched IED.");
+
     public IoTestSessionActionResult StopAll(string reason = "Stopped by operator")
     {
         ThrowIfDisposed();
@@ -344,6 +362,26 @@ private IoTestSessionController GetOrCreateController(IoTestIedPlan ied)
         }
     }
 
+    private IoTestSessionActionResult TargetAction(
+        IoTestIedPlan? ied,
+        Func<IoTestSessionController, IoTestSessionActionResult> action,
+        string missingMessage)
+    {
+        ThrowIfDisposed();
+        if (ied == null)
+            return IoTestSessionActionResult.Failure(missingMessage);
+
+        IoTestSessionController? controller;
+        lock (_sync)
+            _controllers.TryGetValue(ied, out controller);
+        if (controller == null)
+            return IoTestSessionActionResult.Failure(missingMessage);
+
+        var result = action(controller);
+        RaiseProjectionProperties();
+        return result;
+    }
+
     private IoTestSessionActionResult SelectedAction(
         Func<IoTestSessionController, IoTestSessionActionResult> action,
         string missingMessage)
diff --git a/tools/fat_m4_production_adapter_patch.py b/tools/fat_m4_production_adapter_patch.py
deleted file mode 100644
index 5ff704611..000000000
--- a/tools/fat_m4_production_adapter_patch.py
+++ /dev/null
@@ -1,204 +0,0 @@
-from pathlib import Path
-
-
-def replace_exact(path: Path, old: str, new: str, expected: int = 1) -> None:
-    text = path.read_text(encoding="utf-8")
-    count = text.count(old)
-    if count != expected:
-        raise SystemExit(f"{path}: expected {expected} occurrence(s), found {count}: {old[:100]!r}")
-    path.write_text(text.replace(old, new), encoding="utf-8")
-
-
-coordinator = Path("Services/IoTesting/IoTestMultiSessionCoordinator.cs")
-window = Path("IoListTestingWindow.xaml.cs")
-
-replace_exact(
-    coordinator,
-    '''    public IoTestSessionActionResult Pause(string reason = "Paused by operator")
-        => SelectedAction(
-            controller => controller.Pause(reason),
-            "No FAT evidence session is active for the selected IED.");
-
-    public IoTestSessionActionResult Resume()
-        => SelectedAction(
-            controller => controller.Resume(),
-            "No paused or interrupted FAT evidence session belongs to the selected IED.");
-
-    public IoTestSessionActionResult Stop(string reason = "Stopped by operator")
-        => SelectedAction(
-            controller => controller.Stop(reason),
-            "No FAT evidence session is active for the selected IED.");
-''',
-    '''    public IoTestSessionActionResult Pause(string reason = "Paused by operator")
-        => SelectedAction(
-            controller => controller.Pause(reason),
-            "No FAT evidence session is active for the selected IED.");
-
-    public IoTestSessionActionResult Pause(IoTestIedPlan? ied, string reason = "Paused by operator")
-        => TargetAction(
-            ied,
-            controller => controller.Pause(reason),
-            "No FAT evidence session is active for the latched IED.");
-
-    public IoTestSessionActionResult Resume()
-        => SelectedAction(
-            controller => controller.Resume(),
-            "No paused or interrupted FAT evidence session belongs to the selected IED.");
-
-    public IoTestSessionActionResult Resume(IoTestIedPlan? ied)
-        => TargetAction(
-            ied,
-            controller => controller.Resume(),
-            "No paused or interrupted FAT evidence session belongs to the latched IED.");
-
-    public IoTestSessionActionResult Stop(string reason = "Stopped by operator")
-        => SelectedAction(
-            controller => controller.Stop(reason),
-            "No FAT evidence session is active for the selected IED.");
-
-    public IoTestSessionActionResult Stop(IoTestIedPlan? ied, string reason = "Stopped by operator")
-        => TargetAction(
-            ied,
-            controller => controller.Stop(reason),
-            "No FAT evidence session is active for the latched IED.");
-''')
-
-replace_exact(
-    coordinator,
-    '''    private IoTestSessionActionResult SelectedAction(
-        Func<IoTestSessionController, IoTestSessionActionResult> action,
-        string missingMessage)
-''',
-    '''    private IoTestSessionActionResult TargetAction(
-        IoTestIedPlan? ied,
-        Func<IoTestSessionController, IoTestSessionActionResult> action,
-        string missingMessage)
-    {
-        ThrowIfDisposed();
-        if (ied == null)
-            return IoTestSessionActionResult.Failure(missingMessage);
-
-        IoTestSessionController? controller;
-        lock (_sync)
-            _controllers.TryGetValue(ied, out controller);
-        if (controller == null)
-            return IoTestSessionActionResult.Failure(missingMessage);
-
-        var result = action(controller);
-        RaiseProjectionProperties();
-        return result;
-    }
-
-    private IoTestSessionActionResult SelectedAction(
-        Func<IoTestSessionController, IoTestSessionActionResult> action,
-        string missingMessage)
-''')
-
-replace_exact(
-    window,
-    '''        // Capture target latch: keep this local IED for the complete async prepare +
-        // Start transaction even if the global Engineering Explorer changes selection.
-        var selectedIed = SelectedIed;
-        if (selectedIed?.IsPreparing == true)
-            return;
-
-        var preflight = IoTestSessionPreflight.Validate(selectedIed);
-        if (!preflight.Succeeded)
-        {
-            ShowActionResult(preflight, "FAT session scope is not ready");
-            return;
-        }
-
-        PreparationStatusText = $"Connecting {selectedIed!.IedName} · {selectedIed.IpAddress}:102";
-''',
-    '''        // M4 freezes both the IED owner and exact evidence scope before any asynchronous
-        // Engineering preparation. Explorer navigation may continue, but it cannot redirect
-        // this transaction or silently widen the production capture scope.
-        var requestedIed = SelectedIed;
-        if (requestedIed?.IsPreparing == true)
-            return;
-
-        IoFatCaptureTargetLease captureLease;
-        try
-        {
-            captureLease = IoFatProductionControllerAdapter.LatchStartTarget(Project, requestedIed);
-        }
-        catch (InvalidOperationException ex)
-        {
-            ShowActionResult(
-                IoTestSessionActionResult.Failure(ex.Message),
-                "FAT session scope is not ready");
-            return;
-        }
-
-        var selectedIed = captureLease.Ied;
-        PreparationStatusText = $"Connecting {selectedIed.IedName} · {selectedIed.IpAddress}:102";
-''')
-
-replace_exact(
-    window,
-    '''            var result = Session.Start(selectedIed);
-''',
-    '''            // Revalidate the frozen identity/configuration only after Engineering has
-            // completed connection preparation. The adapter delegates to the unchanged
-            // production session controller, which remains the sole evidence writer.
-            var result = IoFatProductionControllerAdapter.StartLatched(Project, Session, captureLease);
-''')
-
-replace_exact(
-    window,
-    '''    private void PauseSession_Click(object sender, RoutedEventArgs e)
-    {
-        var result = Session.Pause();
-        ShowActionResult(result, "FAT session could not pause");
-        if (result.Succeeded)
-            Storage?.SaveNow();
-    }
-
-    private void ResumeSession_Click(object sender, RoutedEventArgs e)
-    {
-        var result = Session.Resume();
-        ShowActionResult(result, "FAT session could not resume");
-        if (result.Succeeded)
-            Storage?.ScheduleSave();
-    }
-
-    private void StopSession_Click(object sender, RoutedEventArgs e)
-    {
-        var result = Session.Stop();
-        ShowActionResult(result, "FAT session could not stop");
-        if (result.Succeeded)
-            Storage?.SaveNow();
-    }
-''',
-    '''    private void PauseSession_Click(object sender, RoutedEventArgs e)
-    {
-        var targetIed = SelectedIed;
-        var result = Session.Pause(targetIed);
-        ShowActionResult(result, "FAT session could not pause");
-        if (result.Succeeded)
-            Storage?.SaveNow();
-    }
-
-    private void ResumeSession_Click(object sender, RoutedEventArgs e)
-    {
-        // Continue is explicitly IED-targeted. A later Explorer change cannot make the
-        // production controller rebind this active evidence session to another device.
-        var targetIed = SelectedIed;
-        var result = Session.Resume(targetIed);
-        ShowActionResult(result, "FAT session could not resume");
-        if (result.Succeeded)
-            Storage?.ScheduleSave();
-    }
-
-    private void StopSession_Click(object sender, RoutedEventArgs e)
-    {
-        var targetIed = SelectedIed;
-        var result = Session.Stop(targetIed);
-        ShowActionResult(result, "FAT session could not stop");
-        if (result.Succeeded)
-            Storage?.SaveNow();
-    }
-''')
-
-print("M4 production adapter wiring applied")

From 7a1570b93def948f6a87d4d3db5d0708583cf87f Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 13:56:02 +0700
Subject: [PATCH 49/84] FAT M6: lock embedded production report preview parity

---
 ...uctionFatM6ReportPreviewRegressionTests.cs | 128 ++++++++++++++++++
 1 file changed, 128 insertions(+)
 create mode 100644 tests/ARSAS.Tests/ProductionFatM6ReportPreviewRegressionTests.cs

diff --git a/tests/ARSAS.Tests/ProductionFatM6ReportPreviewRegressionTests.cs b/tests/ARSAS.Tests/ProductionFatM6ReportPreviewRegressionTests.cs
new file mode 100644
index 000000000..25ba7687c
--- /dev/null
+++ b/tests/ARSAS.Tests/ProductionFatM6ReportPreviewRegressionTests.cs
@@ -0,0 +1,128 @@
+namespace ARSAS.Tests;
+
+public sealed class ProductionFatM6ReportPreviewRegressionTests
+{
+    [Fact]
+    public void EmbeddedFat_UsesExactProductionPreviewInsideTheSameCenter()
+    {
+        var xaml = File.ReadAllText(FindRepoFile("IoListTestingWindow.xaml"));
+        var embedded = File.ReadAllText(FindRepoFile("IoListTestingWindow.EmbeddedEngineeringHost.cs"));
+        var preview = File.ReadAllText(FindRepoFile("IoListTestingWindow.PrintPreview.cs"));
+        var productionTab = File.ReadAllText(FindRepoFile("MainWindow.ProductionFatTab.cs"));
+
+        Assert.Contains("x:Name=\"WorkspacePreviewToggle\"", xaml, StringComparison.Ordinal);
+        Assert.Contains("Content=\"Print Preview\"", xaml, StringComparison.Ordinal);
+        Assert.Contains("Click=\"TogglePrintPreview_Click\"", xaml, StringComparison.Ordinal);
+
+        Assert.Contains("InstallPerIedPrintPreview();", embedded, StringComparison.Ordinal);
+        Assert.Contains("_printPreviewToggle = WorkspacePreviewToggle;", embedded, StringComparison.Ordinal);
+        Assert.Contains("DetachProductionFatCentralWorkspace", embedded, StringComparison.Ordinal);
+
+        // MainWindow hosts the exact detached production center. Explorer and Command Dock
+        // remain owned by the workstation shell; preview never replaces MainWindow itself.
+        Assert.Contains("_nativeFatTab.Content = surface;", productionTab, StringComparison.Ordinal);
+        Assert.Contains("global Engineering IED Explorer and shared Command Dock remain authoritative", productionTab, StringComparison.Ordinal);
+
+        var install = ExtractMethod(preview, "private void InstallPerIedPrintPreview()");
+        Assert.Contains("_signalWorkspaceGrid = workspaceGrid.Children.OfType<DataGrid>().FirstOrDefault();", install, StringComparison.Ordinal);
+        Assert.Contains("_printPreviewHost = BuildPrintPreviewHost();", install, StringComparison.Ordinal);
+        Assert.Contains("workspaceGrid.Children.Add(_printPreviewHost);", install, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void PreviewToggle_PreservesTheExactProductionGridInstanceAndCaptureSession()
+    {
+        var source = File.ReadAllText(FindRepoFile("IoListTestingWindow.PrintPreview.cs"));
+        var toggle = ExtractMethod(source, "private void TogglePrintPreview_Click(object sender, RoutedEventArgs e)");
+
+        Assert.Contains("_signalWorkspaceGrid.Visibility = _printPreviewActive ? Visibility.Collapsed : Visibility.Visible;", toggle, StringComparison.Ordinal);
+        Assert.Contains("_printPreviewHost.Visibility = _printPreviewActive ? Visibility.Visible : Visibility.Collapsed;", toggle, StringComparison.Ordinal);
+        Assert.Contains("RefreshPrintPreview();", toggle, StringComparison.Ordinal);
+
+        // M6 is an in-place view switch. Recreating the grid would lose scroll/selection,
+        // while touching session lifecycle here could redirect or interrupt an active capture.
+        Assert.DoesNotContain("new DataGrid", toggle, StringComparison.Ordinal);
+        Assert.DoesNotContain("Session.Stop", toggle, StringComparison.Ordinal);
+        Assert.DoesNotContain("Session.Pause", toggle, StringComparison.Ordinal);
+        Assert.DoesNotContain("Session.Resume", toggle, StringComparison.Ordinal);
+        Assert.DoesNotContain("Cancel", toggle, StringComparison.Ordinal);
+        Assert.DoesNotContain("Dispose", toggle, StringComparison.Ordinal);
+        Assert.DoesNotContain("Show()", toggle, StringComparison.Ordinal);
+        Assert.DoesNotContain("ShowDialog", toggle, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void PreviewAndNativePdf_ShareOneReportLayoutAuthority()
+    {
+        var preview = File.ReadAllText(FindRepoFile("IoListTestingWindow.PrintPreview.cs"));
+        var documentBuilder = File.ReadAllText(FindRepoFile("Services/IoTesting/IoFatReportPreviewDocumentBuilder.cs"));
+        var pdf = File.ReadAllText(FindRepoFile("Services/IoTesting/IoFatPdfReportService.cs"));
+
+        var refresh = ExtractMethod(preview, "private void RefreshPrintPreview()");
+        Assert.Contains("IoFatReportPreviewService.CreateIedScopedProject(Project, SelectedIed)", refresh, StringComparison.Ordinal);
+        Assert.Contains("IoFatReportPreviewDocumentBuilder.Build(scopedProject, draft)", refresh, StringComparison.Ordinal);
+        Assert.Contains("Session.IsSessionActive && ReferenceEquals(Session.ActiveIed, SelectedIed)", refresh, StringComparison.Ordinal);
+
+        Assert.Contains("IoFatPdfReportService.BuildLayout(project, generatedAt, draft)", documentBuilder, StringComparison.Ordinal);
+        Assert.Contains("var layout = BuildLayout(project, generatedAt, draft: false);", pdf, StringComparison.Ordinal);
+        Assert.Contains("IoFatNativePdfWriter.Build(layout, project)", pdf, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void ActivePreview_TracksViewedIedAndEvidenceWithoutStoppingCapture()
+    {
+        var source = File.ReadAllText(FindRepoFile("IoListTestingWindow.PrintPreview.cs"));
+
+        Assert.Contains("_printPreviewActive && e.PropertyName == nameof(SelectedIed)", source, StringComparison.Ordinal);
+        Assert.Contains("e.PropertyName is nameof(Session.State) or nameof(Session.EvidenceRecordCount)", source, StringComparison.Ordinal);
+        Assert.Contains("Dispatcher.BeginInvoke(DispatcherPriority.Background, RefreshPrintPreview)", source, StringComparison.Ordinal);
+    }
+
+    private static string ExtractMethod(string source, string signature)
+    {
+        var start = source.IndexOf(signature, StringComparison.Ordinal);
+        Assert.True(start >= 0, $"Could not find method '{signature}'.");
+
+        var openBrace = source.IndexOf('{', start);
+        Assert.True(openBrace >= 0, $"Could not find opening brace for '{signature}'.");
+
+        var depth = 0;
+        for (var index = openBrace; index < source.Length; index++)
+        {
+            switch (source[index])
+            {
+                case '{':
+                    depth++;
+                    break;
+                case '}':
+                    depth--;
+                    if (depth == 0)
+                        return source[start..(index + 1)];
+                    break;
+            }
+        }
+
+        throw new InvalidDataException($"Method '{signature}' has no balanced closing brace.");
+    }
+
+    private static string FindRepoFile(string relativePath)
+        => Path.Combine(FindRepoRoot(), relativePath);
+
+    private static string FindRepoRoot()
+    {
+        DirectoryInfo? directory = new(AppContext.BaseDirectory);
+        while (directory != null)
+        {
+            if (File.Exists(Path.Combine(directory.FullName, "MainWindow.xaml")) &&
+                Directory.Exists(Path.Combine(directory.FullName, "tests", "ARSAS.Tests")))
+            {
+                return directory.FullName;
+            }
+
+            directory = directory.Parent;
+        }
+
+        throw new DirectoryNotFoundException(
+            $"Could not locate repository root from '{AppContext.BaseDirectory}'.");
+    }
+}

From 8c0d2aaabb0b55c65f824e628f1169da4bbcb6ab Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 13:56:37 +0700
Subject: [PATCH 50/84] FAT M7: remove obsolete native side-panel report
 preview

---
 MainWindow.NativeFatReportPreview.cs | 279 ---------------------------
 1 file changed, 279 deletions(-)
 delete mode 100644 MainWindow.NativeFatReportPreview.cs

diff --git a/MainWindow.NativeFatReportPreview.cs b/MainWindow.NativeFatReportPreview.cs
deleted file mode 100644
index bda0a5a72..000000000
--- a/MainWindow.NativeFatReportPreview.cs
+++ /dev/null
@@ -1,279 +0,0 @@
-using System.Collections.Specialized;
-using System.ComponentModel;
-using System.Runtime.CompilerServices;
-using System.Windows;
-using System.Windows.Controls;
-using System.Windows.Data;
-using System.Windows.Media;
-using System.Windows.Threading;
-using ArIED61850Tester.Models;
-using ArIED61850Tester.Services;
-
-namespace ArIED61850Tester;
-
-/// <summary>
-/// P2 report-preview hardening for the native FAT workspace. The preview consumes an
-/// immutable evidence snapshot instead of the live row objects, while the main FAT grid
-/// remains directly bound to Explorer/runtime values for testing.
-/// </summary>
-public partial class MainWindow
-{
-    private DispatcherTimer? _nativeFatReportPreviewInstallRetry;
-    private TextBlock? _nativeFatPreviewEvidenceText;
-    private NativeFatReportSnapshot? _nativeFatReportSnapshot;
-    private readonly HashSet<NativeFatSignalRow> _nativeFatReportObservedRows = new();
-    private bool _nativeFatReportPreviewEnhanced;
-    private bool _nativeFatReportRefreshQueued;
-
-    [ModuleInitializer]
-    internal static void RegisterNativeFatReportPreviewEnhancement()
-    {
-        EventManager.RegisterClassHandler(
-            typeof(MainWindow),
-            FrameworkElement.LoadedEvent,
-            new RoutedEventHandler(NativeFatReportPreview_MainWindowLoaded),
-            handledEventsToo: true);
-    }
-
-    private static void NativeFatReportPreview_MainWindowLoaded(object sender, RoutedEventArgs e)
-    {
-        if (sender is not MainWindow window || window._nativeFatReportPreviewEnhanced)
-            return;
-
-        window.Dispatcher.BeginInvoke(
-            DispatcherPriority.ApplicationIdle,
-            new Action(window.TryInstallNativeFatReportPreviewEnhancement));
-    }
-
-    private void TryInstallNativeFatReportPreviewEnhancement()
-    {
-        if (_nativeFatReportPreviewEnhanced || !IsLoaded)
-            return;
-
-        if (!_nativeFatInstalled || _nativeFatPreviewPane?.Child is not Grid previewRoot ||
-            _nativeFatPreviewGrid == null || _nativeFatPreviewSummaryText == null)
-        {
-            _nativeFatReportPreviewInstallRetry ??= new DispatcherTimer(DispatcherPriority.ApplicationIdle)
-            {
-                Interval = TimeSpan.FromMilliseconds(180)
-            };
-            _nativeFatReportPreviewInstallRetry.Tick -= NativeFatReportPreviewInstallRetry_Tick;
-            _nativeFatReportPreviewInstallRetry.Tick += NativeFatReportPreviewInstallRetry_Tick;
-            _nativeFatReportPreviewInstallRetry.Start();
-            return;
-        }
-
-        _nativeFatReportPreviewInstallRetry?.Stop();
-        _nativeFatReportPreviewEnhanced = true;
-
-        // The initial P2 pane already has title/device/summary/grid/persistence rows. Add
-        // one compact evidence inspector between the grid and persistence note.
-        previewRoot.RowDefinitions.Insert(5, new RowDefinition { Height = GridLength.Auto });
-        if (_nativeFatPersistenceText != null)
-            Grid.SetRow(_nativeFatPersistenceText, 6);
-
-        _nativeFatPreviewEvidenceText = new TextBlock
-        {
-            Text = "Select a report row to inspect captured evidence.",
-            Margin = new Thickness(0, 8, 0, 0),
-            Padding = new Thickness(8, 7, 8, 7),
-            FontSize = 9.4,
-            Foreground = ResourceBrush("Muted", Color.FromRgb(0x66, 0x75, 0x8B)),
-            Background = new SolidColorBrush(Color.FromRgb(0xF7, 0xF9, 0xFC)),
-            TextWrapping = TextWrapping.Wrap
-        };
-        Grid.SetRow(_nativeFatPreviewEvidenceText, 5);
-        previewRoot.Children.Add(_nativeFatPreviewEvidenceText);
-
-        // Existing preview columns deliberately use property names also exposed by the
-        // snapshot row. Add the canonical IEC identity so report scope can be audited.
-        if (_nativeFatPreviewGrid.Columns.All(column => !Equals(column.Header, "IEC")))
-        {
-            _nativeFatPreviewGrid.Columns.Insert(1, new DataGridTextColumn
-            {
-                Header = "IEC",
-                Binding = new Binding(nameof(NativeFatReportRow.IecReference)) { Mode = BindingMode.OneWay },
-                Width = new DataGridLength(1.15, DataGridLengthUnitType.Star),
-                MinWidth = 105
-            });
-        }
-
-        if (_nativeFatPreviewGrid.Columns.Count >= 5)
-        {
-            _nativeFatPreviewGrid.Columns[0].Width = new DataGridLength(1.15, DataGridLengthUnitType.Star);
-            _nativeFatPreviewGrid.Columns[2].Width = new DataGridLength(0.58, DataGridLengthUnitType.Star);
-            _nativeFatPreviewGrid.Columns[3].Width = new DataGridLength(0.58, DataGridLengthUnitType.Star);
-            _nativeFatPreviewGrid.Columns[4].Width = new DataGridLength(0.62, DataGridLengthUnitType.Star);
-        }
-
-        _nativeFatPreviewGrid.SelectionChanged += NativeFatPreviewGrid_SelectionChanged;
-        _nativeFatPreviewPane!.IsVisibleChanged += NativeFatPreviewPane_IsVisibleChanged;
-        _nativeFatRows.CollectionChanged += NativeFatReportRows_CollectionChanged;
-        if (_nativeFatShowHistoricalCheck != null)
-        {
-            _nativeFatShowHistoricalCheck.Checked += NativeFatReportScope_Changed;
-            _nativeFatShowHistoricalCheck.Unchecked += NativeFatReportScope_Changed;
-        }
-
-        SyncNativeFatReportRowSubscriptions();
-        Closed += NativeFatReportPreview_MainWindowClosed;
-        QueueNativeFatReportPreviewRefresh();
-    }
-
-    private void NativeFatReportPreviewInstallRetry_Tick(object? sender, EventArgs e)
-    {
-        _nativeFatReportPreviewInstallRetry?.Stop();
-        TryInstallNativeFatReportPreviewEnhancement();
-    }
-
-    private void NativeFatPreviewPane_IsVisibleChanged(object sender, DependencyPropertyChangedEventArgs e)
-    {
-        if (_nativeFatPreviewPane?.IsVisible == true && _nativeFatPreviewColumn != null)
-        {
-            // 330 px was enough for a four-column mock preview but not for auditable IEC
-            // identity + evidence. Keep it compact while making the report pane useful.
-            _nativeFatPreviewColumn.Width = new GridLength(430);
-            QueueNativeFatReportPreviewRefresh();
-        }
-    }
-
-    private void NativeFatReportRows_CollectionChanged(object? sender, NotifyCollectionChangedEventArgs e)
-    {
-        SyncNativeFatReportRowSubscriptions();
-        QueueNativeFatReportPreviewRefresh();
-    }
-
-    private void SyncNativeFatReportRowSubscriptions()
-    {
-        var current = _nativeFatRows.ToHashSet();
-        foreach (var row in _nativeFatReportObservedRows.Where(row => !current.Contains(row)).ToArray())
-        {
-            row.PropertyChanged -= NativeFatReportRow_PropertyChanged;
-            _nativeFatReportObservedRows.Remove(row);
-        }
-
-        foreach (var row in current)
-        {
-            if (!_nativeFatReportObservedRows.Add(row))
-                continue;
-            row.PropertyChanged += NativeFatReportRow_PropertyChanged;
-        }
-    }
-
-    private void NativeFatReportRow_PropertyChanged(object? sender, PropertyChangedEventArgs e)
-    {
-        if (e.PropertyName is nameof(NativeFatSignalRow.Value1Text) or
-            nameof(NativeFatSignalRow.Value2Text) or
-            nameof(NativeFatSignalRow.Result) or
-            nameof(NativeFatSignalRow.HistoryText) or
-            nameof(NativeFatSignalRow.IsHistorical))
-        {
-            QueueNativeFatReportPreviewRefresh();
-        }
-    }
-
-    private void NativeFatReportScope_Changed(object sender, RoutedEventArgs e)
-        => QueueNativeFatReportPreviewRefresh();
-
-    private void QueueNativeFatReportPreviewRefresh()
-    {
-        if (!_nativeFatReportPreviewEnhanced || _nativeFatPreviewPane?.IsVisible != true || _nativeFatReportRefreshQueued)
-            return;
-
-        _nativeFatReportRefreshQueued = true;
-        Dispatcher.BeginInvoke(
-            DispatcherPriority.ContextIdle,
-            new Action(() =>
-            {
-                _nativeFatReportRefreshQueued = false;
-                RefreshNativeFatReportPreviewSnapshot();
-            }));
-    }
-
-    private void RefreshNativeFatReportPreviewSnapshot()
-    {
-        if (_nativeFatPreviewPane?.IsVisible != true || _nativeFatPreviewGrid == null)
-            return;
-
-        var device = SelectedDevice;
-        var state = _nativeFatCurrentState;
-        if (device == null || state == null ||
-            !state.DeviceId.Equals(device.DeviceId, StringComparison.OrdinalIgnoreCase))
-        {
-            _nativeFatReportSnapshot = null;
-            _nativeFatPreviewGrid.ItemsSource = null;
-            if (_nativeFatPreviewSummaryText != null)
-                _nativeFatPreviewSummaryText.Text = "Select an IED with a loaded FAT state.";
-            if (_nativeFatPreviewEvidenceText != null)
-                _nativeFatPreviewEvidenceText.Text = "No report evidence is loaded.";
-            return;
-        }
-
-        var previousReference = (_nativeFatPreviewGrid.SelectedItem as NativeFatReportRow)?.IecReference;
-        _nativeFatReportSnapshot = NativeFatReportSnapshotBuilder.Build(device, state);
-        var showHistorical = _nativeFatShowHistoricalCheck?.IsChecked == true;
-        var visibleRows = _nativeFatReportSnapshot.Rows
-            .Where(row => showHistorical || !row.IsHistorical)
-            .ToArray();
-        _nativeFatPreviewGrid.ItemsSource = visibleRows;
-
-        if (_nativeFatPreviewDeviceText != null)
-            _nativeFatPreviewDeviceText.Text = $"IED · {_nativeFatReportSnapshot.IedName} · {_nativeFatReportSnapshot.IpAddress}:{_nativeFatReportSnapshot.Port}";
-        if (_nativeFatPreviewSummaryText != null)
-        {
-            var scopeSuffix = !showHistorical && _nativeFatReportSnapshot.HistoricalCount > 0
-                ? " · historical hidden"
-                : string.Empty;
-            _nativeFatPreviewSummaryText.Text = _nativeFatReportSnapshot.SummaryText + scopeSuffix;
-        }
-
-        NativeFatReportRow? selection = null;
-        if (!string.IsNullOrWhiteSpace(previousReference))
-        {
-            selection = visibleRows.FirstOrDefault(row =>
-                row.IecReference.Equals(previousReference, StringComparison.OrdinalIgnoreCase));
-        }
-        selection ??= visibleRows.FirstOrDefault();
-        if (selection != null)
-        {
-            _nativeFatPreviewGrid.SelectedItem = selection;
-            _nativeFatPreviewGrid.ScrollIntoView(selection);
-        }
-        else
-        {
-            UpdateNativeFatPreviewEvidence(null);
-        }
-    }
-
-    private void NativeFatPreviewGrid_SelectionChanged(object sender, SelectionChangedEventArgs e)
-        => UpdateNativeFatPreviewEvidence(_nativeFatPreviewGrid?.SelectedItem as NativeFatReportRow);
-
-    private void UpdateNativeFatPreviewEvidence(NativeFatReportRow? row)
-    {
-        if (_nativeFatPreviewEvidenceText == null)
-            return;
-
-        _nativeFatPreviewEvidenceText.Text = row?.EvidenceSummaryText ??
-                                             "Select a report row to inspect captured evidence.";
-    }
-
-    private void NativeFatReportPreview_MainWindowClosed(object? sender, EventArgs e)
-    {
-        _nativeFatReportPreviewInstallRetry?.Stop();
-        if (_nativeFatPreviewGrid != null)
-            _nativeFatPreviewGrid.SelectionChanged -= NativeFatPreviewGrid_SelectionChanged;
-        if (_nativeFatPreviewPane != null)
-            _nativeFatPreviewPane.IsVisibleChanged -= NativeFatPreviewPane_IsVisibleChanged;
-        _nativeFatRows.CollectionChanged -= NativeFatReportRows_CollectionChanged;
-        if (_nativeFatShowHistoricalCheck != null)
-        {
-            _nativeFatShowHistoricalCheck.Checked -= NativeFatReportScope_Changed;
-            _nativeFatShowHistoricalCheck.Unchecked -= NativeFatReportScope_Changed;
-        }
-
-        foreach (var row in _nativeFatReportObservedRows)
-            row.PropertyChanged -= NativeFatReportRow_PropertyChanged;
-        _nativeFatReportObservedRows.Clear();
-        Closed -= NativeFatReportPreview_MainWindowClosed;
-    }
-}

From 4d8d77371684c6c15111d0c612258558461d53da Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 13:56:54 +0700
Subject: [PATCH 51/84] FAT M7: guard single production preview authority

---
 .../ProductionFatM7CleanupRegressionTests.cs  | 56 +++++++++++++++++++
 1 file changed, 56 insertions(+)
 create mode 100644 tests/ARSAS.Tests/ProductionFatM7CleanupRegressionTests.cs

diff --git a/tests/ARSAS.Tests/ProductionFatM7CleanupRegressionTests.cs b/tests/ARSAS.Tests/ProductionFatM7CleanupRegressionTests.cs
new file mode 100644
index 000000000..2ca8e0131
--- /dev/null
+++ b/tests/ARSAS.Tests/ProductionFatM7CleanupRegressionTests.cs
@@ -0,0 +1,56 @@
+namespace ARSAS.Tests;
+
+public sealed class ProductionFatM7CleanupRegressionTests
+{
+    [Fact]
+    public void ObsoleteNativeSidePanelPreview_IsNotASecondFatPreviewAuthority()
+    {
+        var repoRoot = FindRepoRoot();
+        Assert.False(
+            File.Exists(Path.Combine(repoRoot, "MainWindow.NativeFatReportPreview.cs")),
+            "The retired native FAT side-panel preview must not return. Production FAT owns one in-place report preview.");
+
+        var productionPreview = File.ReadAllText(Path.Combine(repoRoot, "IoListTestingWindow.PrintPreview.cs"));
+        var embeddedHost = File.ReadAllText(Path.Combine(repoRoot, "IoListTestingWindow.EmbeddedEngineeringHost.cs"));
+
+        Assert.Contains("BuildPrintPreviewHost", productionPreview, StringComparison.Ordinal);
+        Assert.Contains("IoFatReportPreviewDocumentBuilder.Build(scopedProject, draft)", productionPreview, StringComparison.Ordinal);
+        Assert.Contains("InstallPerIedPrintPreview();", embeddedHost, StringComparison.Ordinal);
+        Assert.Contains("_printPreviewToggle = WorkspacePreviewToggle;", embeddedHost, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void Cleanup_DoesNotRetireProductionCapturePreflightOrEngineeringAcquisitionAuthority()
+    {
+        var bootstrap = File.ReadAllText(FindRepoFile("MainWindow.ProductionFatEngineeringBootstrap.cs"));
+        var adapter = File.ReadAllText(FindRepoFile("Services/IoTesting/IoFatProductionControllerAdapter.cs"));
+        var contract = File.ReadAllText(FindRepoFile("docs/FAT_ENGINEERING_WORKSTATION_CONTRACT.md"));
+
+        Assert.Contains("AdoptEngineeringRuntimeWorkspaces", bootstrap, StringComparison.Ordinal);
+        Assert.Contains("IoTestSessionPreflight.Validate", bootstrap, StringComparison.Ordinal);
+        Assert.Contains("IoFatProductionControllerAdapter", adapter, StringComparison.Ordinal);
+        Assert.Contains("production FAT", contract, StringComparison.OrdinalIgnoreCase);
+        Assert.Contains("Engineering", contract, StringComparison.OrdinalIgnoreCase);
+    }
+
+    private static string FindRepoFile(string relativePath)
+        => Path.Combine(FindRepoRoot(), relativePath);
+
+    private static string FindRepoRoot()
+    {
+        DirectoryInfo? directory = new(AppContext.BaseDirectory);
+        while (directory != null)
+        {
+            if (File.Exists(Path.Combine(directory.FullName, "MainWindow.xaml")) &&
+                Directory.Exists(Path.Combine(directory.FullName, "tests", "ARSAS.Tests")))
+            {
+                return directory.FullName;
+            }
+
+            directory = directory.Parent;
+        }
+
+        throw new DirectoryNotFoundException(
+            $"Could not locate repository root from '{AppContext.BaseDirectory}'.");
+    }
+}

From bd6c083e57cceac76fa24e4e2a452a94c1464eb7 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 13:59:50 +0700
Subject: [PATCH 52/84] FAT M7: remove obsolete native preview history
 inspector

---
 MainWindow.NativeFatHistoryInspector.cs | 178 ------------------------
 1 file changed, 178 deletions(-)
 delete mode 100644 MainWindow.NativeFatHistoryInspector.cs

diff --git a/MainWindow.NativeFatHistoryInspector.cs b/MainWindow.NativeFatHistoryInspector.cs
deleted file mode 100644
index 27b24d82c..000000000
--- a/MainWindow.NativeFatHistoryInspector.cs
+++ /dev/null
@@ -1,178 +0,0 @@
-using System.Runtime.CompilerServices;
-using System.Text;
-using System.Windows;
-using System.Windows.Controls;
-using System.Windows.Threading;
-using ArIED61850Tester.Models;
-
-namespace ArIED61850Tester;
-
-/// <summary>
-/// Makes the native FAT report preview useful as an operator evidence/history inspector.
-/// The immutable report snapshot remains the preview/export authority; this enhancement
-/// only appends the persisted chronological audit trail for the selected IEC identity.
-/// </summary>
-public partial class MainWindow
-{
-    private DispatcherTimer? _nativeFatHistoryInspectorInstallRetry;
-    private ScrollViewer? _nativeFatHistoryScrollViewer;
-    private bool _nativeFatHistoryInspectorAttached;
-    private bool _nativeFatHistoryRenderQueued;
-
-    [ModuleInitializer]
-    internal static void RegisterNativeFatHistoryInspector()
-    {
-        EventManager.RegisterClassHandler(
-            typeof(MainWindow),
-            FrameworkElement.LoadedEvent,
-            new RoutedEventHandler(NativeFatHistoryInspector_MainWindowLoaded),
-            handledEventsToo: true);
-    }
-
-    private static void NativeFatHistoryInspector_MainWindowLoaded(object sender, RoutedEventArgs e)
-    {
-        if (sender is not MainWindow window || window._nativeFatHistoryInspectorAttached)
-            return;
-
-        window.Dispatcher.BeginInvoke(
-            DispatcherPriority.ApplicationIdle,
-            new Action(window.TryAttachNativeFatHistoryInspector));
-    }
-
-    private void TryAttachNativeFatHistoryInspector()
-    {
-        if (_nativeFatHistoryInspectorAttached || !IsLoaded)
-            return;
-
-        if (!_nativeFatReportPreviewEnhanced ||
-            _nativeFatPreviewPane?.Child is not Grid previewRoot ||
-            _nativeFatPreviewGrid == null ||
-            _nativeFatPreviewEvidenceText == null)
-        {
-            _nativeFatHistoryInspectorInstallRetry ??= new DispatcherTimer(DispatcherPriority.ApplicationIdle)
-            {
-                Interval = TimeSpan.FromMilliseconds(180)
-            };
-            _nativeFatHistoryInspectorInstallRetry.Tick -= NativeFatHistoryInspectorInstallRetry_Tick;
-            _nativeFatHistoryInspectorInstallRetry.Tick += NativeFatHistoryInspectorInstallRetry_Tick;
-            _nativeFatHistoryInspectorInstallRetry.Start();
-            return;
-        }
-
-        _nativeFatHistoryInspectorInstallRetry?.Stop();
-        _nativeFatHistoryInspectorAttached = true;
-
-        // The evidence block can become long once retest history exists. Keep the report
-        // pane compact and give only the evidence/history area its own vertical scrolling.
-        if (previewRoot.Children.Contains(_nativeFatPreviewEvidenceText))
-            previewRoot.Children.Remove(_nativeFatPreviewEvidenceText);
-
-        _nativeFatPreviewEvidenceText.Margin = new Thickness(0);
-        _nativeFatPreviewEvidenceText.TextWrapping = TextWrapping.Wrap;
-        _nativeFatHistoryScrollViewer = new ScrollViewer
-        {
-            Content = _nativeFatPreviewEvidenceText,
-            Margin = new Thickness(0, 8, 0, 0),
-            MaxHeight = 190,
-            VerticalScrollBarVisibility = ScrollBarVisibility.Auto,
-            HorizontalScrollBarVisibility = ScrollBarVisibility.Disabled,
-            CanContentScroll = false
-        };
-        Grid.SetRow(_nativeFatHistoryScrollViewer, 5);
-        previewRoot.Children.Add(_nativeFatHistoryScrollViewer);
-
-        _nativeFatPreviewGrid.SelectionChanged += NativeFatHistoryInspector_SelectionChanged;
-        Closed += NativeFatHistoryInspector_MainWindowClosed;
-        QueueNativeFatHistoryInspectorRender();
-    }
-
-    private void NativeFatHistoryInspectorInstallRetry_Tick(object? sender, EventArgs e)
-    {
-        _nativeFatHistoryInspectorInstallRetry?.Stop();
-        TryAttachNativeFatHistoryInspector();
-    }
-
-    private void NativeFatHistoryInspector_SelectionChanged(object sender, SelectionChangedEventArgs e)
-        => QueueNativeFatHistoryInspectorRender();
-
-    private void QueueNativeFatHistoryInspectorRender()
-    {
-        if (!_nativeFatHistoryInspectorAttached || _nativeFatHistoryRenderQueued)
-            return;
-
-        _nativeFatHistoryRenderQueued = true;
-        Dispatcher.BeginInvoke(
-            DispatcherPriority.ContextIdle,
-            new Action(() =>
-            {
-                _nativeFatHistoryRenderQueued = false;
-                RenderNativeFatHistoryInspector();
-            }));
-    }
-
-    private void RenderNativeFatHistoryInspector()
-    {
-        if (_nativeFatPreviewEvidenceText == null)
-            return;
-
-        if (_nativeFatPreviewGrid?.SelectedItem is not NativeFatReportRow reportRow)
-        {
-            _nativeFatPreviewEvidenceText.Text = "Select a report row to inspect captured evidence and retest history.";
-            return;
-        }
-
-        var text = new StringBuilder(reportRow.EvidenceSummaryText);
-        var state = _nativeFatCurrentState;
-        var key = NativeFatIdentity.BuildKey(reportRow.IecReference, reportRow.FunctionalConstraint);
-        var persisted = state?.Signals.FirstOrDefault(signal =>
-            signal.Key.Equals(key, StringComparison.OrdinalIgnoreCase));
-        var history = persisted?.History ?? new List<NativeFatHistoryEntry>();
-
-        text.Append("\n\nHISTORY · latest first");
-        if (history.Count == 0)
-        {
-            text.Append("\nNo previous capture/result transitions recorded.");
-        }
-        else
-        {
-            foreach (var entry in history
-                         .OrderByDescending(item => item.TimestampUtc)
-                         .Take(8))
-            {
-                text.Append("\n")
-                    .Append(entry.TimestampUtc.ToLocalTime().ToString("yyyy-MM-dd HH:mm:ss"))
-                    .Append("  ·  ")
-                    .Append(string.IsNullOrWhiteSpace(entry.Action) ? "State update" : entry.Action.Trim());
-
-                if (!string.IsNullOrWhiteSpace(entry.Result))
-                    text.Append("  ·  ").Append(entry.Result.Trim());
-                if (entry.Value1 != null)
-                    text.Append("  ·  V1=").Append(entry.Value1.Value);
-                if (entry.Value2 != null)
-                    text.Append("  ·  V2=").Append(entry.Value2.Value);
-                if (!string.IsNullOrWhiteSpace(entry.Note))
-                    text.Append("  ·  ").Append(entry.Note.Trim());
-            }
-
-            if (history.Count > 8)
-                text.Append("\n+").Append(history.Count - 8).Append(" earlier record(s) retained in the per-IED JSON.");
-        }
-
-        if (reportRow.IsHistorical)
-            text.Append("\n\nThis IEC identity is historical: it is no longer in the current Explorer scope, but its FAT evidence is retained.");
-
-        _nativeFatPreviewEvidenceText.Text = text.ToString();
-        _nativeFatHistoryScrollViewer?.ScrollToTop();
-    }
-
-    private void NativeFatHistoryInspector_MainWindowClosed(object? sender, EventArgs e)
-    {
-        _nativeFatHistoryInspectorInstallRetry?.Stop();
-        if (_nativeFatPreviewGrid != null)
-            _nativeFatPreviewGrid.SelectionChanged -= NativeFatHistoryInspector_SelectionChanged;
-        Closed -= NativeFatHistoryInspector_MainWindowClosed;
-        _nativeFatHistoryInspectorAttached = false;
-        _nativeFatHistoryRenderQueued = false;
-        _nativeFatHistoryScrollViewer = null;
-    }
-}

From df62112d7ae8170f986ec81196d7877d1e609dd1 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 14:00:17 +0700
Subject: [PATCH 53/84] FAT M7: guard removal of obsolete preview inspector
 stack

---
 tests/ARSAS.Tests/ProductionFatM7CleanupRegressionTests.cs | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tests/ARSAS.Tests/ProductionFatM7CleanupRegressionTests.cs b/tests/ARSAS.Tests/ProductionFatM7CleanupRegressionTests.cs
index 2ca8e0131..f01434676 100644
--- a/tests/ARSAS.Tests/ProductionFatM7CleanupRegressionTests.cs
+++ b/tests/ARSAS.Tests/ProductionFatM7CleanupRegressionTests.cs
@@ -3,12 +3,15 @@ namespace ARSAS.Tests;
 public sealed class ProductionFatM7CleanupRegressionTests
 {
     [Fact]
-    public void ObsoleteNativeSidePanelPreview_IsNotASecondFatPreviewAuthority()
+    public void ObsoleteNativeSidePanelPreviewStack_IsNotASecondFatPreviewAuthority()
     {
         var repoRoot = FindRepoRoot();
         Assert.False(
             File.Exists(Path.Combine(repoRoot, "MainWindow.NativeFatReportPreview.cs")),
             "The retired native FAT side-panel preview must not return. Production FAT owns one in-place report preview.");
+        Assert.False(
+            File.Exists(Path.Combine(repoRoot, "MainWindow.NativeFatHistoryInspector.cs")),
+            "The retired side-panel history inspector depended on the obsolete native preview and must not return as a second preview stack.");
 
         var productionPreview = File.ReadAllText(Path.Combine(repoRoot, "IoListTestingWindow.PrintPreview.cs"));
         var embeddedHost = File.ReadAllText(Path.Combine(repoRoot, "IoListTestingWindow.EmbeddedEngineeringHost.cs"));

From e373118122e25602934b37ad8cb54fa0e54fb2ee Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 14:06:34 +0700
Subject: [PATCH 54/84] FAT M7: align M3 latch regression with production
 controller adapter

---
 ...ionFatM3SelectedIedBindingRegressionTests.cs | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/tests/ARSAS.Tests/ProductionFatM3SelectedIedBindingRegressionTests.cs b/tests/ARSAS.Tests/ProductionFatM3SelectedIedBindingRegressionTests.cs
index 31c628f40..c8d50ce60 100644
--- a/tests/ARSAS.Tests/ProductionFatM3SelectedIedBindingRegressionTests.cs
+++ b/tests/ARSAS.Tests/ProductionFatM3SelectedIedBindingRegressionTests.cs
@@ -8,12 +8,17 @@ public void Start_LatchesCaptureTarget_WithoutTakingOverViewedContext()
         var window = Read("IoListTestingWindow.xaml.cs");
         var coordinator = Read("Services/IoTesting/IoTestMultiSessionCoordinator.cs");
 
-        var latch = window.IndexOf("var selectedIed = SelectedIed;", StringComparison.Ordinal);
-        var prepare = window.IndexOf("await engineeringWindow.PrepareIoTestIedForFatAsync(", latch, StringComparison.Ordinal);
-        var start = window.IndexOf("Session.Start(selectedIed)", latch, StringComparison.Ordinal);
-        Assert.True(latch >= 0, "Start FAT must latch the currently viewed IED before asynchronous preparation.");
-        Assert.True(prepare > latch, "Engineering acquisition must use the latched target.");
-        Assert.True(start > prepare, "The production session must start the same latched target after preparation.");
+        var requested = window.IndexOf("var requestedIed = SelectedIed;", StringComparison.Ordinal);
+        var latch = window.IndexOf("IoFatProductionControllerAdapter.LatchStartTarget(Project, requestedIed)", requested, StringComparison.Ordinal);
+        var selected = window.IndexOf("var selectedIed = captureLease.Ied;", latch, StringComparison.Ordinal);
+        var prepare = window.IndexOf("await engineeringWindow.PrepareIoTestIedForFatAsync(", selected, StringComparison.Ordinal);
+        var start = window.IndexOf("IoFatProductionControllerAdapter.StartLatched(Project, Session, captureLease)", prepare, StringComparison.Ordinal);
+
+        Assert.True(requested >= 0, "Start FAT must read the currently viewed IED before asynchronous preparation.");
+        Assert.True(latch > requested, "Production FAT must freeze the IED and exact capture scope before asynchronous preparation.");
+        Assert.True(selected > latch, "The preparation target must come from the frozen production capture lease.");
+        Assert.True(prepare > selected, "Engineering acquisition must prepare the latched target.");
+        Assert.True(start > prepare, "The production session must start from the same frozen lease after preparation.");
 
         var startBody = MethodBody(
             coordinator,

From 025447a48e9bb7698afc9b1192be1339b5c708b1 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 14:06:53 +0700
Subject: [PATCH 55/84] FAT M7: keep cleanup guard on the current preflight
 authority

---
 tests/ARSAS.Tests/ProductionFatM7CleanupRegressionTests.cs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/ARSAS.Tests/ProductionFatM7CleanupRegressionTests.cs b/tests/ARSAS.Tests/ProductionFatM7CleanupRegressionTests.cs
index f01434676..5b75b0369 100644
--- a/tests/ARSAS.Tests/ProductionFatM7CleanupRegressionTests.cs
+++ b/tests/ARSAS.Tests/ProductionFatM7CleanupRegressionTests.cs
@@ -30,7 +30,7 @@ public void Cleanup_DoesNotRetireProductionCapturePreflightOrEngineeringAcquisit
         var contract = File.ReadAllText(FindRepoFile("docs/FAT_ENGINEERING_WORKSTATION_CONTRACT.md"));
 
         Assert.Contains("AdoptEngineeringRuntimeWorkspaces", bootstrap, StringComparison.Ordinal);
-        Assert.Contains("IoTestSessionPreflight.Validate", bootstrap, StringComparison.Ordinal);
+        Assert.Contains("IoTestSessionPreflight.Validate", adapter, StringComparison.Ordinal);
         Assert.Contains("IoFatProductionControllerAdapter", adapter, StringComparison.Ordinal);
         Assert.Contains("production FAT", contract, StringComparison.OrdinalIgnoreCase);
         Assert.Contains("Engineering", contract, StringComparison.OrdinalIgnoreCase);

From aa1160453e8ce82221026f32e3d9368e56e641d2 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 15:43:52 +0700
Subject: [PATCH 56/84] M7 retire duplicate native FAT workspace authority

---
 MainWindow.NativeFatWorkspace.cs | 888 +------------------------------
 1 file changed, 8 insertions(+), 880 deletions(-)

diff --git a/MainWindow.NativeFatWorkspace.cs b/MainWindow.NativeFatWorkspace.cs
index 422219781..e5d4f545e 100644
--- a/MainWindow.NativeFatWorkspace.cs
+++ b/MainWindow.NativeFatWorkspace.cs
@@ -1,900 +1,28 @@
-using System.Collections.ObjectModel;
-using System.Collections.Specialized;
-using System.ComponentModel;
-using System.Runtime.CompilerServices;
-using System.Windows;
-using System.Windows.Controls;
-using System.Windows.Controls.Primitives;
-using System.Windows.Data;
-using System.Windows.Input;
-using System.Windows.Media;
-using System.Windows.Media.Animation;
+using System;
 using System.Windows.Threading;
-using ArIED61850Tester.Models;
-using ArIED61850Tester.Services;
 
 namespace ArIED61850Tester;
 
 /// <summary>
-/// Native continuous FAT workspace layered on the persistent P0/P1 Engineering shell.
+/// M7 compatibility bridge for the canonical seventh Engineering destination.
 ///
-/// Authority boundary:
-/// - IED Explorer owns SelectedDevice, signal engineering, live value and acquisition.
-/// - the shared Command Dock remains the only command UI/runtime owner.
-/// - this workspace owns only FAT captures, result/history and per-IED persistence.
-///
-/// The legacy IoListTestingWindow remains untouched as a compatibility fallback while
-/// report/evidence parity is migrated incrementally.
+/// MainWindow.xaml owns the FAT tab and navigation button. Production FAT is mounted
+/// into that permanent XAML slot by MainWindow.ProductionFatTab.cs. This file deliberately
+/// owns no FAT rows, capture commands, evidence state, persistence, preview, export, or timers.
+/// It retains only the shared slot index and a deferred navigation-geometry refresh used by
+/// the canonical MainWindow shell.
 /// </summary>
 public partial class MainWindow
 {
     private const int NativeFatWorkspaceIndex = 6;
 
-    private readonly NativeFatStateStore _nativeFatStore = new();
-    private readonly ObservableCollection<NativeFatSignalRow> _nativeFatRows = new();
-    private readonly Dictionary<string, NativeFatDeviceState> _nativeFatStateCache = new(StringComparer.OrdinalIgnoreCase);
-    private readonly SemaphoreSlim _nativeFatSaveGate = new(1, 1);
-
-    private DispatcherTimer? _nativeFatInstallRetry;
-    private DispatcherTimer? _nativeFatReconcileTimer;
-    private DispatcherTimer? _nativeFatSaveTimer;
-    private CancellationTokenSource? _nativeFatLoadCts;
-    private TabItem? _nativeFatTab;
-    private Button? _nativeFatNavButton;
-    private DataGrid? _nativeFatGrid;
-    private DataGrid? _nativeFatPreviewGrid;
-    private ICollectionView? _nativeFatView;
-    private TextBox? _nativeFatSearchBox;
-    private CheckBox? _nativeFatShowHistoricalCheck;
-    private Border? _nativeFatPreviewPane;
-    private ColumnDefinition? _nativeFatPreviewGapColumn;
-    private ColumnDefinition? _nativeFatPreviewColumn;
-    private TextBlock? _nativeFatContextText;
-    private TextBlock? _nativeFatStatusText;
-    private TextBlock? _nativeFatPreviewDeviceText;
-    private TextBlock? _nativeFatPreviewSummaryText;
-    private TextBlock? _nativeFatPersistenceText;
-    private Iec61850MonitorDevice? _nativeFatObservedDevice;
-    private NativeFatDeviceState? _nativeFatCurrentState;
-    private bool _nativeFatInstalled;
-    private bool _nativeFatLoading;
-    private bool _nativeFatPreviewVisible;
-
-    [ModuleInitializer]
-    internal static void RegisterNativeFatWorkspace()
-    {
-        EventManager.RegisterClassHandler(
-            typeof(MainWindow),
-            FrameworkElement.LoadedEvent,
-            new RoutedEventHandler(NativeFatWorkspace_MainWindowLoaded),
-            handledEventsToo: true);
-    }
-
-    private static void NativeFatWorkspace_MainWindowLoaded(object sender, RoutedEventArgs e)
-    {
-        if (sender is not MainWindow window || window._nativeFatInstalled)
-            return;
-
-        // P0 moves MainTabs/Explorer/Command Dock at ContextIdle. Install FAT after that
-        // re-parenting has settled so this stacked feature never races the stable P0 shell.
-        window.Dispatcher.BeginInvoke(
-            DispatcherPriority.ApplicationIdle,
-            new Action(window.TryInstallNativeFatWorkspace));
-    }
-
-    private void TryInstallNativeFatWorkspace()
-    {
-        if (_nativeFatInstalled || !IsLoaded)
-            return;
-
-        if (_persistentWorkbench == null || MainTabs.Items.Count < 6)
-        {
-            _nativeFatInstallRetry ??= new DispatcherTimer(DispatcherPriority.ApplicationIdle)
-            {
-                Interval = TimeSpan.FromMilliseconds(140)
-            };
-            _nativeFatInstallRetry.Tick -= NativeFatInstallRetry_Tick;
-            _nativeFatInstallRetry.Tick += NativeFatInstallRetry_Tick;
-            _nativeFatInstallRetry.Start();
-            return;
-        }
-
-        _nativeFatInstallRetry?.Stop();
-        _nativeFatInstalled = true;
-
-        // M1: MainWindow.xaml owns the seventh tab and navigation button. The native
-        // FAT implementation temporarily supplies only content/state until the production
-        // reusable FAT surface replaces it in M2; it no longer creates workstation shell UI.
-        _nativeFatTab = NativeFatTab;
-        _nativeFatNavButton = NavNativeFatButton;
-        _nativeFatTab.Content = BuildNativeFatWorkspaceContent();
-
-        // The command dock is deliberately shared, not cloned. FAT is command-centric,
-        // therefore start with the same expanded behavior as Explorer/Event Log.
-        _persistentWorkbench.DockExpandedByWorkspace[NativeFatWorkspaceIndex] = true;
-        InstallNativeFatTimers();
-        AttachNativeFatObservedDevice(SelectedDevice);
-
-        PropertyChanged += NativeFat_MainWindowPropertyChanged;
-        MainTabs.SelectionChanged += NativeFat_MainTabsSelectionChanged;
-        SizeChanged += NativeFat_MainWindowSizeChanged;
-        Closed += NativeFat_MainWindowClosed;
-
-        QueueNativeFatNavigationGeometry();
-        UpdateNativeFatSummary();
-    }
-
-    private void NativeFatInstallRetry_Tick(object? sender, EventArgs e)
-    {
-        _nativeFatInstallRetry?.Stop();
-        TryInstallNativeFatWorkspace();
-    }
-
-    private UIElement BuildNativeFatWorkspaceContent()
-    {
-        var root = new Grid { Margin = new Thickness(0) };
-        root.RowDefinitions.Add(new RowDefinition { Height = GridLength.Auto });
-        root.RowDefinitions.Add(new RowDefinition { Height = new GridLength(8) });
-        root.RowDefinitions.Add(new RowDefinition { Height = GridLength.Auto });
-        root.RowDefinitions.Add(new RowDefinition { Height = new GridLength(8) });
-        root.RowDefinitions.Add(new RowDefinition { Height = new GridLength(1, GridUnitType.Star) });
-
-        var header = BuildNativeFatHeader();
-        Grid.SetRow(header, 0);
-        root.Children.Add(header);
-
-        var toolbar = BuildNativeFatToolbar();
-        Grid.SetRow(toolbar, 2);
-        root.Children.Add(toolbar);
-
-        var body = BuildNativeFatBody();
-        Grid.SetRow(body, 4);
-        root.Children.Add(body);
-        return root;
-    }
-
-    private Border BuildNativeFatHeader()
-    {
-        var border = new Border
-        {
-            Padding = new Thickness(14, 10, 14, 10),
-            CornerRadius = new CornerRadius(12),
-            Background = ResourceBrush("SurfaceElevated", Colors.White),
-            BorderBrush = ResourceBrush("Line", Color.FromRgb(0xDD, 0xE5, 0xF0)),
-            BorderThickness = new Thickness(1)
-        };
-
-        var grid = new Grid();
-        grid.ColumnDefinitions.Add(new ColumnDefinition { Width = new GridLength(1, GridUnitType.Star) });
-        grid.ColumnDefinitions.Add(new ColumnDefinition { Width = GridLength.Auto });
-
-        var titleStack = new StackPanel();
-        titleStack.Children.Add(new TextBlock
-        {
-            Text = "FAT · Continuous Testing",
-            FontSize = 14.5,
-            FontWeight = FontWeights.SemiBold,
-            Foreground = ResourceBrush("Ink", Color.FromRgb(0x20, 0x30, 0x4A))
-        });
-        titleStack.Children.Add(new TextBlock
-        {
-            Text = "Explorer signal authority · live values stay shared · captures autosave per IED · removed signals keep their history",
-            Margin = new Thickness(0, 3, 0, 0),
-            FontSize = 10.8,
-            Foreground = ResourceBrush("Muted", Color.FromRgb(0x66, 0x75, 0x8B)),
-            TextWrapping = TextWrapping.Wrap
-        });
-        grid.Children.Add(titleStack);
-
-        _nativeFatContextText = new TextBlock
-        {
-            Text = "IED · NONE",
-            FontSize = 10.5,
-            FontWeight = FontWeights.SemiBold,
-            Foreground = ResourceBrush("Accent", Color.FromRgb(0x25, 0x63, 0xEB)),
-            VerticalAlignment = VerticalAlignment.Center,
-            Margin = new Thickness(14, 0, 0, 0)
-        };
-        Grid.SetColumn(_nativeFatContextText, 1);
-        grid.Children.Add(_nativeFatContextText);
-
-        border.Child = grid;
-        return border;
-    }
-
-    private Border BuildNativeFatToolbar()
-    {
-        var border = new Border
-        {
-            Padding = new Thickness(9, 7, 9, 7),
-            CornerRadius = new CornerRadius(11),
-            Background = ResourceBrush("Surface", Colors.White),
-            BorderBrush = ResourceBrush("Line", Color.FromRgb(0xDD, 0xE5, 0xF0)),
-            BorderThickness = new Thickness(1)
-        };
-
-        var wrap = new WrapPanel
-        {
-            Orientation = Orientation.Horizontal,
-            VerticalAlignment = VerticalAlignment.Center
-        };
-
-        _nativeFatSearchBox = new TextBox
-        {
-            Width = 210,
-            Height = 30,
-            Margin = new Thickness(0, 0, 8, 0),
-            Padding = new Thickness(8, 4, 8, 4),
-            VerticalContentAlignment = VerticalAlignment.Center,
-            ToolTip = "Search Signal, IEC reference, type, value, result or history state"
-        };
-        _nativeFatSearchBox.TextChanged += NativeFatSearchBox_TextChanged;
-        wrap.Children.Add(_nativeFatSearchBox);
-
-        wrap.Children.Add(CreateNativeFatButton("Refresh", NativeFatRefresh_Click, "Reconcile the saved FAT state with the current Explorer signal scope."));
-        wrap.Children.Add(CreateNativeFatButton("Capture V1", NativeFatCapture1_Click, "Capture the current Explorer live value into Value 1 for selected FAT rows."));
-        wrap.Children.Add(CreateNativeFatButton("Capture V2", NativeFatCapture2_Click, "Capture the current Explorer live value into Value 2 for selected FAT rows."));
-        wrap.Children.Add(CreateNativeFatButton("PASS", NativeFatPass_Click, "Mark selected FAT rows PASS; previous results remain in history."));
-        wrap.Children.Add(CreateNativeFatButton("REVIEW", NativeFatReview_Click, "Mark selected FAT rows REVIEW; previous results remain in history."));
-        wrap.Children.Add(CreateNativeFatButton("FAIL", NativeFatFail_Click, "Mark selected FAT rows FAIL; previous results remain in history."));
-        wrap.Children.Add(CreateNativeFatButton("Reset current", NativeFatReset_Click, "Clear current captures/result while retaining the previous state in history."));
-        wrap.Children.Add(CreateNativeFatButton("Report Preview", NativeFatReportPreview_Click, "Show or hide the native FAT report preview without opening another FAT runtime."));
-
-        _nativeFatShowHistoricalCheck = new CheckBox
-        {
-            Content = "Show historical",
-            IsChecked = false,
-            Margin = new Thickness(7, 6, 7, 0),
-            VerticalAlignment = VerticalAlignment.Center,
-            FontSize = 10.7,
-            Foreground = ResourceBrush("Muted", Color.FromRgb(0x66, 0x75, 0x8B)),
-            ToolTip = "Show signals removed from the current Explorer/SCL scope. Their previous FAT evidence is never deleted."
-        };
-        _nativeFatShowHistoricalCheck.Checked += NativeFatShowHistorical_Changed;
-        _nativeFatShowHistoricalCheck.Unchecked += NativeFatShowHistorical_Changed;
-        wrap.Children.Add(_nativeFatShowHistoricalCheck);
-
-        _nativeFatStatusText = new TextBlock
-        {
-            Text = "Select an IED to begin.",
-            Margin = new Thickness(9, 7, 0, 0),
-            VerticalAlignment = VerticalAlignment.Center,
-            FontSize = 10.4,
-            Foreground = ResourceBrush("Muted", Color.FromRgb(0x66, 0x75, 0x8B))
-        };
-        wrap.Children.Add(_nativeFatStatusText);
-
-        border.Child = wrap;
-        return border;
-    }
-
-    private Grid BuildNativeFatBody()
-    {
-        var body = new Grid();
-        body.ColumnDefinitions.Add(new ColumnDefinition { Width = new GridLength(1, GridUnitType.Star), MinWidth = 0 });
-        _nativeFatPreviewGapColumn = new ColumnDefinition { Width = new GridLength(0) };
-        _nativeFatPreviewColumn = new ColumnDefinition { Width = new GridLength(0), MinWidth = 0 };
-        body.ColumnDefinitions.Add(_nativeFatPreviewGapColumn);
-        body.ColumnDefinitions.Add(_nativeFatPreviewColumn);
-
-        _nativeFatGrid = BuildNativeFatGrid(preview: false);
-        Grid.SetColumn(_nativeFatGrid, 0);
-        body.Children.Add(_nativeFatGrid);
-
-        _nativeFatPreviewPane = BuildNativeFatPreviewPane();
-        _nativeFatPreviewPane.Visibility = Visibility.Collapsed;
-        Grid.SetColumn(_nativeFatPreviewPane, 2);
-        body.Children.Add(_nativeFatPreviewPane);
-        return body;
-    }
-
-    private DataGrid BuildNativeFatGrid(bool preview)
-    {
-        var grid = new DataGrid
-        {
-            AutoGenerateColumns = false,
-            CanUserAddRows = false,
-            CanUserDeleteRows = false,
-            CanUserReorderColumns = true,
-            CanUserResizeColumns = true,
-            HeadersVisibility = DataGridHeadersVisibility.Column,
-            IsReadOnly = true,
-            SelectionMode = preview ? DataGridSelectionMode.Single : DataGridSelectionMode.Extended,
-            SelectionUnit = DataGridSelectionUnit.FullRow,
-            GridLinesVisibility = DataGridGridLinesVisibility.Horizontal,
-            HorizontalGridLinesBrush = ResourceBrush("Line", Color.FromRgb(0xE2, 0xE8, 0xF0)),
-            BorderBrush = ResourceBrush("Line", Color.FromRgb(0xDD, 0xE5, 0xF0)),
-            BorderThickness = new Thickness(1),
-            RowHeight = preview ? 29 : 32,
-            ColumnHeaderHeight = 31,
-            Background = ResourceBrush("Surface", Colors.White),
-            AlternatingRowBackground = new SolidColorBrush(Color.FromRgb(0xFA, 0xFB, 0xFD)),
-            EnableRowVirtualization = true,
-            EnableColumnVirtualization = true
-        };
-
-        if (TryFindResource("DataGridHeaderCompact") is Style headerStyle)
-            grid.ColumnHeaderStyle = headerStyle;
-        if (TryFindResource("DataGridCellCompact") is Style cellStyle)
-            grid.CellStyle = cellStyle;
-
-        var rowStyle = new Style(typeof(DataGridRow));
-        rowStyle.Setters.Add(new Setter(Control.FontSizeProperty, preview ? 10.0 : 10.4));
-        var historicalTrigger = new DataTrigger
-        {
-            Binding = new Binding(nameof(NativeFatSignalRow.IsHistorical)),
-            Value = true
-        };
-        historicalTrigger.Setters.Add(new Setter(UIElement.OpacityProperty, 0.56));
-        rowStyle.Triggers.Add(historicalTrigger);
-        grid.RowStyle = rowStyle;
-
-        if (!preview)
-        {
-            grid.Columns.Add(TextColumn("SIGNAL", nameof(NativeFatSignalRow.SignalName), 1.25, minWidth: 130));
-            grid.Columns.Add(TextColumn("IEC REFERENCE", nameof(NativeFatSignalRow.IecReference), 1.85, minWidth: 190));
-            grid.Columns.Add(TextColumn("TYPE", nameof(NativeFatSignalRow.DataType), 0.72, minWidth: 72));
-            grid.Columns.Add(TextColumn("LIVE VALUE", nameof(NativeFatSignalRow.LiveValue), 0.9, minWidth: 90));
-            grid.Columns.Add(TextColumn("QUALITY", nameof(NativeFatSignalRow.Quality), 0.82, minWidth: 82));
-            grid.Columns.Add(TextColumn("VALUE 1", nameof(NativeFatSignalRow.Value1Text), 0.78, minWidth: 78));
-            grid.Columns.Add(TextColumn("VALUE 2", nameof(NativeFatSignalRow.Value2Text), 0.78, minWidth: 78));
-            grid.Columns.Add(TextColumn("STATUS", nameof(NativeFatSignalRow.StatusText), 0.72, minWidth: 76));
-            grid.Columns.Add(TextColumn("RESULT", nameof(NativeFatSignalRow.Result), 0.72, minWidth: 72));
-            grid.Columns.Add(TextColumn("HISTORY", nameof(NativeFatSignalRow.HistoryText), 0.78, minWidth: 78));
-        }
-        else
-        {
-            grid.Columns.Add(TextColumn("SIGNAL", nameof(NativeFatSignalRow.SignalName), 1.35, minWidth: 115));
-            grid.Columns.Add(TextColumn("V1", nameof(NativeFatSignalRow.Value1Text), 0.65, minWidth: 62));
-            grid.Columns.Add(TextColumn("V2", nameof(NativeFatSignalRow.Value2Text), 0.65, minWidth: 62));
-            grid.Columns.Add(TextColumn("RESULT", nameof(NativeFatSignalRow.Result), 0.72, minWidth: 68));
-        }
-
-        return grid;
-    }
-
-    private Border BuildNativeFatPreviewPane()
-    {
-        var border = new Border
-        {
-            Padding = new Thickness(11),
-            CornerRadius = new CornerRadius(12),
-            Background = ResourceBrush("SurfaceElevated", Colors.White),
-            BorderBrush = ResourceBrush("Line", Color.FromRgb(0xDD, 0xE5, 0xF0)),
-            BorderThickness = new Thickness(1)
-        };
-
-        var grid = new Grid();
-        grid.RowDefinitions.Add(new RowDefinition { Height = GridLength.Auto });
-        grid.RowDefinitions.Add(new RowDefinition { Height = GridLength.Auto });
-        grid.RowDefinitions.Add(new RowDefinition { Height = GridLength.Auto });
-        grid.RowDefinitions.Add(new RowDefinition { Height = new GridLength(8) });
-        grid.RowDefinitions.Add(new RowDefinition { Height = new GridLength(1, GridUnitType.Star) });
-        grid.RowDefinitions.Add(new RowDefinition { Height = GridLength.Auto });
-
-        var title = new TextBlock
-        {
-            Text = "FAT Report Preview",
-            FontSize = 13,
-            FontWeight = FontWeights.SemiBold,
-            Foreground = ResourceBrush("Ink", Color.FromRgb(0x20, 0x30, 0x4A))
-        };
-        grid.Children.Add(title);
-
-        _nativeFatPreviewDeviceText = new TextBlock
-        {
-            Text = "IED · NONE",
-            Margin = new Thickness(0, 4, 0, 0),
-            FontSize = 10.6,
-            FontWeight = FontWeights.SemiBold,
-            Foreground = ResourceBrush("Accent", Color.FromRgb(0x25, 0x63, 0xEB))
-        };
-        Grid.SetRow(_nativeFatPreviewDeviceText, 1);
-        grid.Children.Add(_nativeFatPreviewDeviceText);
-
-        _nativeFatPreviewSummaryText = new TextBlock
-        {
-            Text = "No FAT state loaded.",
-            Margin = new Thickness(0, 4, 0, 0),
-            FontSize = 10.2,
-            Foreground = ResourceBrush("Muted", Color.FromRgb(0x66, 0x75, 0x8B)),
-            TextWrapping = TextWrapping.Wrap
-        };
-        Grid.SetRow(_nativeFatPreviewSummaryText, 2);
-        grid.Children.Add(_nativeFatPreviewSummaryText);
-
-        _nativeFatPreviewGrid = BuildNativeFatGrid(preview: true);
-        Grid.SetRow(_nativeFatPreviewGrid, 4);
-        grid.Children.Add(_nativeFatPreviewGrid);
-
-        _nativeFatPersistenceText = new TextBlock
-        {
-            Text = "Per-IED JSON · non-destructive reconciliation",
-            Margin = new Thickness(0, 7, 0, 0),
-            FontSize = 9.5,
-            Foreground = ResourceBrush("Muted", Color.FromRgb(0x66, 0x75, 0x8B)),
-            TextWrapping = TextWrapping.Wrap
-        };
-        Grid.SetRow(_nativeFatPersistenceText, 5);
-        grid.Children.Add(_nativeFatPersistenceText);
-
-        border.Child = grid;
-        return border;
-    }
-
-    private DataGridTextColumn TextColumn(string header, string path, double star, double minWidth)
-        => new()
-        {
-            Header = header,
-            Binding = new Binding(path) { Mode = BindingMode.OneWay },
-            Width = new DataGridLength(star, DataGridLengthUnitType.Star),
-            MinWidth = minWidth
-        };
-
-    private Button CreateNativeFatButton(string text, RoutedEventHandler click, string toolTip)
-    {
-        var button = new Button
-        {
-            Content = text,
-            Margin = new Thickness(0, 0, 6, 0),
-            Padding = new Thickness(9, 5, 9, 5),
-            MinHeight = 29,
-            FontSize = 10.5,
-            ToolTip = toolTip
-        };
-        if (TryFindResource("SoftButton") is Style style)
-            button.Style = style;
-        button.Click += click;
-        return button;
-    }
-
-    private void InstallNativeFatTimers()
-    {
-        _nativeFatReconcileTimer = new DispatcherTimer(DispatcherPriority.Background)
-        {
-            Interval = TimeSpan.FromMilliseconds(320)
-        };
-        _nativeFatReconcileTimer.Tick += NativeFatReconcileTimer_Tick;
-
-        _nativeFatSaveTimer = new DispatcherTimer(DispatcherPriority.Background)
-        {
-            Interval = TimeSpan.FromMilliseconds(350)
-        };
-        _nativeFatSaveTimer.Tick += NativeFatSaveTimer_Tick;
-    }
-
-    private async void NativeFatNavButton_Click(object sender, RoutedEventArgs e)
-    {
-        if (MainTabs.Items.Count <= NativeFatWorkspaceIndex)
-            return;
-
-        MainTabs.SelectedIndex = NativeFatWorkspaceIndex;
-        QueueNativeFatNavigationGeometry();
-        await EnsureNativeFatLoadedAsync(forceReconcile: false);
-    }
-
-    private void NativeFat_MainTabsSelectionChanged(object sender, SelectionChangedEventArgs e)
-    {
-        if (!ReferenceEquals(e.Source, MainTabs))
-            return;
-
-        QueueNativeFatNavigationGeometry();
-        if (MainTabs.SelectedIndex == NativeFatWorkspaceIndex)
-            _ = EnsureNativeFatLoadedAsync(forceReconcile: false);
-        else
-            QueueNativeFatSave();
-    }
-
-    private void NativeFat_MainWindowSizeChanged(object sender, SizeChangedEventArgs e)
-        => QueueNativeFatNavigationGeometry();
-
     private void QueueNativeFatNavigationGeometry()
     {
-        if (!_nativeFatInstalled)
+        if (!IsLoaded)
             return;
 
         Dispatcher.BeginInvoke(
             DispatcherPriority.ApplicationIdle,
             new Action(() => UpdateNavigationVisuals(MainTabs.SelectedIndex, animate: false)));
     }
-
-    private void NativeFat_MainWindowPropertyChanged(object? sender, PropertyChangedEventArgs e)
-    {
-        if (e.PropertyName != nameof(SelectedDevice))
-            return;
-
-        QueueNativeFatSave();
-        AttachNativeFatObservedDevice(SelectedDevice);
-        if (MainTabs.SelectedIndex == NativeFatWorkspaceIndex)
-            _ = EnsureNativeFatLoadedAsync(forceReconcile: true);
-        else
-            UpdateNativeFatSummary();
-    }
-
-    private void AttachNativeFatObservedDevice(Iec61850MonitorDevice? device)
-    {
-        if (ReferenceEquals(_nativeFatObservedDevice, device))
-            return;
-
-        if (_nativeFatObservedDevice != null)
-        {
-            _nativeFatObservedDevice.Signals.CollectionChanged -= NativeFatSignalCollectionChanged;
-            _nativeFatObservedDevice.Points.CollectionChanged -= NativeFatSignalCollectionChanged;
-        }
-
-        _nativeFatObservedDevice = device;
-        if (_nativeFatObservedDevice != null)
-        {
-            _nativeFatObservedDevice.Signals.CollectionChanged += NativeFatSignalCollectionChanged;
-            _nativeFatObservedDevice.Points.CollectionChanged += NativeFatSignalCollectionChanged;
-        }
-    }
-
-    private void NativeFatSignalCollectionChanged(object? sender, NotifyCollectionChangedEventArgs e)
-    {
-        if (MainTabs.SelectedIndex != NativeFatWorkspaceIndex)
-            return;
-        _nativeFatReconcileTimer?.Stop();
-        _nativeFatReconcileTimer?.Start();
-    }
-
-    private async void NativeFatReconcileTimer_Tick(object? sender, EventArgs e)
-    {
-        _nativeFatReconcileTimer?.Stop();
-        await EnsureNativeFatLoadedAsync(forceReconcile: true);
-    }
-
-    private async Task EnsureNativeFatLoadedAsync(bool forceReconcile)
-    {
-        if (!_nativeFatInstalled || MainTabs.SelectedIndex != NativeFatWorkspaceIndex)
-            return;
-
-        var device = SelectedDevice;
-        if (device == null)
-        {
-            ClearNativeFatRows();
-            _nativeFatCurrentState = null;
-            UpdateNativeFatSummary();
-            return;
-        }
-
-        var cacheKey = StableNativeFatDeviceKey(device);
-        if (!forceReconcile && _nativeFatCurrentState != null &&
-            _nativeFatCurrentState.DeviceId.Equals(device.DeviceId, StringComparison.OrdinalIgnoreCase))
-        {
-            UpdateNativeFatSummary();
-            return;
-        }
-
-        _nativeFatLoadCts?.Cancel();
-        _nativeFatLoadCts?.Dispose();
-        _nativeFatLoadCts = CancellationTokenSource.CreateLinkedTokenSource(_applicationCancellation.Token);
-        var token = _nativeFatLoadCts.Token;
-        _nativeFatLoading = true;
-        SetNativeFatStatus($"Loading FAT state for {device.Name}…");
-
-        try
-        {
-            NativeFatDeviceState state;
-            if (_nativeFatStateCache.TryGetValue(cacheKey, out var cached))
-            {
-                state = cached;
-            }
-            else
-            {
-                state = await _nativeFatStore.LoadAsync(device, token);
-                token.ThrowIfCancellationRequested();
-                _nativeFatStateCache[cacheKey] = state;
-            }
-
-            // We are back on the WPF dispatcher here. Reconciliation enumerates Explorer
-            // ObservableCollections only on their owning UI thread.
-            token.ThrowIfCancellationRequested();
-            if (!ReferenceEquals(device, SelectedDevice))
-                return;
-
-            NativeFatStateStore.Reconcile(state, device);
-            _nativeFatCurrentState = state;
-            RebuildNativeFatRows(state, device);
-            QueueNativeFatSave();
-            SetNativeFatStatus($"FAT ready · {device.Name}");
-        }
-        catch (OperationCanceledException)
-        {
-            // Fast IED switches are normal; stale loads are intentionally discarded.
-        }
-        catch (Exception ex)
-        {
-            AddLog("WARN", "Native FAT", $"FAT state load/reconcile failed: {ex.Message}");
-            SetNativeFatStatus("FAT state could not be loaded. Explorer monitoring remains unaffected.");
-        }
-        finally
-        {
-            _nativeFatLoading = false;
-            UpdateNativeFatSummary();
-        }
-    }
-
-    private void RebuildNativeFatRows(NativeFatDeviceState state, Iec61850MonitorDevice device)
-    {
-        ClearNativeFatRows();
-        foreach (var row in NativeFatStateStore.BuildRows(state, device))
-        {
-            row.StateChanged += NativeFatRow_StateChanged;
-            _nativeFatRows.Add(row);
-        }
-
-        _nativeFatView = CollectionViewSource.GetDefaultView(_nativeFatRows);
-        _nativeFatView.Filter = NativeFatViewFilter;
-        if (_nativeFatGrid != null)
-            _nativeFatGrid.ItemsSource = _nativeFatView;
-        if (_nativeFatPreviewGrid != null)
-            _nativeFatPreviewGrid.ItemsSource = _nativeFatRows;
-        UpdateNativeFatSummary();
-    }
-
-    private void ClearNativeFatRows()
-    {
-        foreach (var row in _nativeFatRows)
-        {
-            row.StateChanged -= NativeFatRow_StateChanged;
-            row.Dispose();
-        }
-        _nativeFatRows.Clear();
-        _nativeFatView = null;
-        if (_nativeFatGrid != null)
-            _nativeFatGrid.ItemsSource = null;
-        if (_nativeFatPreviewGrid != null)
-            _nativeFatPreviewGrid.ItemsSource = null;
-    }
-
-    private bool NativeFatViewFilter(object item)
-    {
-        if (item is not NativeFatSignalRow row)
-            return false;
-
-        if (row.IsHistorical && _nativeFatShowHistoricalCheck?.IsChecked != true)
-            return false;
-
-        var query = _nativeFatSearchBox?.Text?.Trim();
-        if (string.IsNullOrWhiteSpace(query))
-            return true;
-
-        return row.SignalName.Contains(query, StringComparison.OrdinalIgnoreCase) ||
-               row.IecReference.Contains(query, StringComparison.OrdinalIgnoreCase) ||
-               row.IecTelegram.Contains(query, StringComparison.OrdinalIgnoreCase) ||
-               row.DataType.Contains(query, StringComparison.OrdinalIgnoreCase) ||
-               row.LiveValue.Contains(query, StringComparison.OrdinalIgnoreCase) ||
-               row.Value1Text.Contains(query, StringComparison.OrdinalIgnoreCase) ||
-               row.Value2Text.Contains(query, StringComparison.OrdinalIgnoreCase) ||
-               row.Result.Contains(query, StringComparison.OrdinalIgnoreCase) ||
-               row.StatusText.Contains(query, StringComparison.OrdinalIgnoreCase);
-    }
-
-    private void NativeFatSearchBox_TextChanged(object sender, TextChangedEventArgs e)
-        => _nativeFatView?.Refresh();
-
-    private void NativeFatShowHistorical_Changed(object sender, RoutedEventArgs e)
-    {
-        _nativeFatView?.Refresh();
-        UpdateNativeFatSummary();
-    }
-
-    private void NativeFatRow_StateChanged(object? sender, EventArgs e)
-    {
-        QueueNativeFatSave();
-        UpdateNativeFatSummary();
-        _nativeFatPreviewGrid?.Items.Refresh();
-    }
-
-    private IReadOnlyList<NativeFatSignalRow> SelectedNativeFatRows()
-    {
-        if (_nativeFatGrid == null)
-            return Array.Empty<NativeFatSignalRow>();
-
-        var selected = _nativeFatGrid.SelectedItems.OfType<NativeFatSignalRow>().ToArray();
-        if (selected.Length > 0)
-            return selected;
-        return _nativeFatGrid.CurrentItem is NativeFatSignalRow current
-            ? new[] { current }
-            : Array.Empty<NativeFatSignalRow>();
-    }
-
-    private void NativeFatRefresh_Click(object sender, RoutedEventArgs e)
-        => _ = EnsureNativeFatLoadedAsync(forceReconcile: true);
-
-    private void NativeFatCapture1_Click(object sender, RoutedEventArgs e)
-        => CaptureNativeFatSelection(1);
-
-    private void NativeFatCapture2_Click(object sender, RoutedEventArgs e)
-        => CaptureNativeFatSelection(2);
-
-    private void CaptureNativeFatSelection(int slot)
-    {
-        var rows = SelectedNativeFatRows();
-        if (rows.Count == 0)
-        {
-            SetNativeFatStatus("Select one or more FAT signals first.");
-            return;
-        }
-
-        var captured = 0;
-        foreach (var row in rows)
-        {
-            if (row.CaptureValue(slot))
-                captured++;
-        }
-        SetNativeFatStatus(captured == 0
-            ? "No selected row has a current Explorer signal source. Historical rows cannot be captured."
-            : $"Captured Value {slot} for {captured} signal(s). Autosave queued.");
-    }
-
-    private void NativeFatPass_Click(object sender, RoutedEventArgs e)
-        => SetNativeFatSelectionResult(NativeFatResult.Pass);
-
-    private void NativeFatReview_Click(object sender, RoutedEventArgs e)
-        => SetNativeFatSelectionResult(NativeFatResult.Review);
-
-    private void NativeFatFail_Click(object sender, RoutedEventArgs e)
-        => SetNativeFatSelectionResult(NativeFatResult.Fail);
-
-    private void SetNativeFatSelectionResult(string result)
-    {
-        var rows = SelectedNativeFatRows();
-        if (rows.Count == 0)
-        {
-            SetNativeFatStatus("Select one or more FAT signals first.");
-            return;
-        }
-
-        foreach (var row in rows)
-            row.SetResult(result);
-        SetNativeFatStatus($"{rows.Count} signal(s) marked {result}. Previous state retained in history.");
-    }
-
-    private void NativeFatReset_Click(object sender, RoutedEventArgs e)
-    {
-        var rows = SelectedNativeFatRows();
-        if (rows.Count == 0)
-        {
-            SetNativeFatStatus("Select one or more FAT signals first.");
-            return;
-        }
-
-        foreach (var row in rows)
-            row.ResetCurrentResult();
-        SetNativeFatStatus($"Reset current FAT state for {rows.Count} signal(s); history was retained.");
-    }
-
-    private void NativeFatReportPreview_Click(object sender, RoutedEventArgs e)
-    {
-        _nativeFatPreviewVisible = !_nativeFatPreviewVisible;
-        if (_nativeFatPreviewPane == null || _nativeFatPreviewGapColumn == null || _nativeFatPreviewColumn == null)
-            return;
-
-        _nativeFatPreviewPane.Visibility = _nativeFatPreviewVisible ? Visibility.Visible : Visibility.Collapsed;
-        _nativeFatPreviewGapColumn.Width = new GridLength(_nativeFatPreviewVisible ? 10 : 0);
-        _nativeFatPreviewColumn.Width = _nativeFatPreviewVisible ? new GridLength(330) : new GridLength(0);
-        UpdateNativeFatSummary();
-    }
-
-    private void QueueNativeFatSave()
-    {
-        if (_nativeFatCurrentState == null || _nativeFatSaveTimer == null)
-            return;
-        _nativeFatSaveTimer.Stop();
-        _nativeFatSaveTimer.Start();
-    }
-
-    private async void NativeFatSaveTimer_Tick(object? sender, EventArgs e)
-    {
-        _nativeFatSaveTimer?.Stop();
-        if (_nativeFatCurrentState != null)
-            await SaveNativeFatStateAsync(_nativeFatCurrentState);
-    }
-
-    private async Task SaveNativeFatStateAsync(NativeFatDeviceState state)
-    {
-        try
-        {
-            await _nativeFatSaveGate.WaitAsync(_applicationCancellation.Token);
-            try
-            {
-                await _nativeFatStore.SaveAsync(state, _applicationCancellation.Token);
-            }
-            finally
-            {
-                _nativeFatSaveGate.Release();
-            }
-
-            if (ReferenceEquals(state, _nativeFatCurrentState))
-            {
-                SetNativeFatStatus($"Saved · {DateTime.Now:HH:mm:ss}");
-                UpdateNativeFatSummary();
-            }
-        }
-        catch (OperationCanceledException)
-        {
-            // Application shutdown or superseded state.
-        }
-        catch (Exception ex)
-        {
-            AddLog("WARN", "Native FAT", $"Autosave failed: {ex.Message}");
-            if (ReferenceEquals(state, _nativeFatCurrentState))
-                SetNativeFatStatus("Autosave failed; current in-memory FAT state is still available.");
-        }
-    }
-
-    private void UpdateNativeFatSummary()
-    {
-        var device = SelectedDevice;
-        var deviceLabel = device == null ? "NONE" : device.Name;
-        if (_nativeFatContextText != null)
-            _nativeFatContextText.Text = $"IED · {deviceLabel}";
-        if (_nativeFatPreviewDeviceText != null)
-            _nativeFatPreviewDeviceText.Text = $"IED · {deviceLabel}";
-
-        var current = _nativeFatRows.Count(row => !row.IsHistorical);
-        var historical = _nativeFatRows.Count(row => row.IsHistorical);
-        var pass = _nativeFatRows.Count(row => !row.IsHistorical && row.Result == NativeFatResult.Pass);
-        var review = _nativeFatRows.Count(row => !row.IsHistorical && row.Result == NativeFatResult.Review);
-        var fail = _nativeFatRows.Count(row => !row.IsHistorical && row.Result == NativeFatResult.Fail);
-        var untested = Math.Max(0, current - pass - review - fail);
-
-        if (_nativeFatPreviewSummaryText != null)
-        {
-            _nativeFatPreviewSummaryText.Text = device == null
-                ? "Select an IED in the persistent Explorer."
-                : $"Current {current} · PASS {pass} · REVIEW {review} · FAIL {fail} · UNTESTED {untested} · historical {historical}";
-        }
-
-        if (_nativeFatPersistenceText != null)
-        {
-            _nativeFatPersistenceText.Text = _nativeFatCurrentState == null
-                ? "Per-IED JSON · non-destructive reconciliation"
-                : $"Resume file: {Path.GetFileName(_nativeFatCurrentState.StoragePath)}\nHistorical IEC identities remain stored when engineering changes.";
-        }
-
-        if (!_nativeFatLoading && device != null && _nativeFatStatusText != null &&
-            (_nativeFatStatusText.Text.StartsWith("Select", StringComparison.OrdinalIgnoreCase) ||
-             _nativeFatStatusText.Text.StartsWith("Loading", StringComparison.OrdinalIgnoreCase)))
-        {
-            _nativeFatStatusText.Text = $"{current} current · {historical} historical · {untested} untested";
-        }
-    }
-
-    private void SetNativeFatStatus(string text)
-    {
-        if (_nativeFatStatusText != null)
-            _nativeFatStatusText.Text = text;
-    }
-
-    private static string StableNativeFatDeviceKey(Iec61850MonitorDevice device)
-        => !string.IsNullOrWhiteSpace(device.DeviceId) ? device.DeviceId : device.Name;
-
-    private Brush ResourceBrush(string key, Color fallback)
-        => TryFindResource(key) as Brush ?? new SolidColorBrush(fallback);
-
-    private void NativeFat_MainWindowClosed(object? sender, EventArgs e)
-    {
-        _nativeFatInstallRetry?.Stop();
-        _nativeFatReconcileTimer?.Stop();
-        _nativeFatSaveTimer?.Stop();
-        _nativeFatLoadCts?.Cancel();
-        _nativeFatLoadCts?.Dispose();
-
-        PropertyChanged -= NativeFat_MainWindowPropertyChanged;
-        MainTabs.SelectionChanged -= NativeFat_MainTabsSelectionChanged;
-        SizeChanged -= NativeFat_MainWindowSizeChanged;
-        Closed -= NativeFat_MainWindowClosed;
-
-        if (_nativeFatObservedDevice != null)
-        {
-            _nativeFatObservedDevice.Signals.CollectionChanged -= NativeFatSignalCollectionChanged;
-            _nativeFatObservedDevice.Points.CollectionChanged -= NativeFatSignalCollectionChanged;
-        }
-
-        ClearNativeFatRows();
-        _nativeFatSaveGate.Dispose();
-    }
 }

From b65ccf9d8f0158fc634388fc32997c121dacab93 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 15:44:17 +0700
Subject: [PATCH 57/84] M7 mount production FAT directly in canonical XAML slot

---
 MainWindow.ProductionFatTab.cs | 44 ++++++++++++----------------------
 1 file changed, 15 insertions(+), 29 deletions(-)

diff --git a/MainWindow.ProductionFatTab.cs b/MainWindow.ProductionFatTab.cs
index 4a8e0f0a0..bc464d5d2 100644
--- a/MainWindow.ProductionFatTab.cs
+++ b/MainWindow.ProductionFatTab.cs
@@ -8,7 +8,7 @@
 namespace ArIED61850Tester;
 
 /// <summary>
-/// P2 FAT pivot: the Engineering FAT tab is a host for the proven production
+/// Engineering FAT pivot: the permanent XAML FAT tab hosts the proven production
 /// IoListTestingWindow workspace rather than a second/manual FAT implementation.
 /// The global Engineering IED Explorer and shared Command Dock remain authoritative.
 /// </summary>
@@ -19,7 +19,7 @@ public partial class MainWindow
     private FrameworkElement? _productionFatSurface;
     private DispatcherTimer? _productionFatInstallRetry;
 
-    internal bool ProductionFatTabReady => _productionFatTabInstalled && _nativeFatTab != null;
+    internal bool ProductionFatTabReady => _productionFatTabInstalled && NativeFatTab != null;
 
     [ModuleInitializer]
     internal static void RegisterProductionFatTabPivot()
@@ -46,10 +46,10 @@ private void TryInstallProductionFatTabPivot()
         if (_productionFatTabInstalled || !IsLoaded)
             return;
 
-        // The seventh FAT destination is now canonical MainWindow XAML. Wait only for the
-        // native FAT state contribution to bind its compatibility fields; do not create,
-        // restyle, or re-own navigation here.
-        if (!_nativeFatInstalled || _nativeFatTab == null || _nativeFatNavButton == null)
+        // M7: MainWindow.xaml is the sole owner of the seventh destination. Wait only
+        // until the canonical XAML tab is present; there is no native FAT runtime to install.
+        if (MainTabs.Items.Count <= NativeFatWorkspaceIndex ||
+            !ReferenceEquals(MainTabs.Items[NativeFatWorkspaceIndex], NativeFatTab))
         {
             _productionFatInstallRetry ??= new DispatcherTimer(DispatcherPriority.ApplicationIdle)
             {
@@ -63,25 +63,14 @@ private void TryInstallProductionFatTabPivot()
 
         _productionFatInstallRetry?.Stop();
         _productionFatTabInstalled = true;
+        NativeFatTab.Content = BuildProductionFatPermanentHost();
 
-        // Retire the experimental manual-capture surface. Keep its code isolated in the
-        // branch for now so this pivot is reversible while production FAT parity is verified.
-        _nativeFatReconcileTimer?.Stop();
-        _nativeFatSaveTimer?.Stop();
-        AttachNativeFatObservedDevice(null);
-        PropertyChanged -= NativeFat_MainWindowPropertyChanged;
-        MainTabs.SelectionChanged -= NativeFat_MainTabsSelectionChanged;
-
-        _nativeFatTab.Content = BuildProductionFatPermanentHost();
-
-        // M2 prewarm starts as soon as the canonical host exists. It is deliberately
-        // independent of the currently selected tab so a valid Engineering SCL/DataSet
+        // Prewarm as soon as the canonical host exists. A valid Engineering SCL/DataSet
         // can prepare the exact production surface before the operator first opens FAT.
         QueueProductionFatEngineeringBootstrap();
 
-        // MainWindow.xaml owns the FAT button's SegmentedNavButton style and NavButton_Click.
-        // Production FAT reacts to tab selection below; it must not install a second click owner.
-        _nativeFatNavButton.ToolTip = "Production FAT workspace · automatic Value 1 / Value 2 evidence capture";
+        // MainWindow.xaml owns both style and click routing for the seventh nav button.
+        NavNativeFatButton.ToolTip = "Production FAT workspace · automatic Value 1 / Value 2 evidence capture";
 
         PropertyChanged += ProductionFat_MainWindowPropertyChanged;
         MainTabs.SelectionChanged += ProductionFat_MainTabsSelectionChanged;
@@ -98,10 +87,8 @@ private void ProductionFatInstallRetry_Tick(object? sender, EventArgs e)
 
     private FrameworkElement BuildProductionFatPermanentHost()
     {
-        // This is a stable shell slot, not a launcher/form. With a valid Engineering
-        // static DataSet it is replaced in the background by the exact production FAT
-        // workspace before first navigation. With no eligible IED it remains a quiet
-        // contextual empty state and never creates an alternate FAT workflow.
+        // Stable shell slot, never a launcher or alternate FAT workflow. With a valid
+        // Engineering static DataSet this is replaced by the exact production FAT surface.
         var root = new Grid { Margin = new Thickness(0) };
         root.Children.Add(new TextBlock
         {
@@ -144,13 +131,13 @@ internal bool MountProductionFatWorkspace(IoListTestingWindow window, FrameworkE
     {
         ArgumentNullException.ThrowIfNull(window);
         ArgumentNullException.ThrowIfNull(surface);
-        if (!ProductionFatTabReady || _nativeFatTab == null)
+        if (!ProductionFatTabReady)
             return false;
 
         _productionFatWindow = window;
         _productionFatSurface = surface;
         surface.DataContext = window;
-        _nativeFatTab.Content = surface;
+        NativeFatTab.Content = surface;
         if (_persistentWorkbench != null)
             _persistentWorkbench.DockExpandedByWorkspace[NativeFatWorkspaceIndex] = true;
 
@@ -176,8 +163,7 @@ internal void UnmountProductionFatWorkspace(IoListTestingWindow window)
         window.Closed -= ProductionFatWindow_Closed;
         _productionFatWindow = null;
         _productionFatSurface = null;
-        if (_nativeFatTab != null)
-            _nativeFatTab.Content = BuildProductionFatPermanentHost();
+        NativeFatTab.Content = BuildProductionFatPermanentHost();
     }
 
     private void ProductionFatWindow_Closed(object? sender, EventArgs e)

From b5a3421b47c59de2025934de6bf4824dfee7dca0 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 15:44:25 +0700
Subject: [PATCH 58/84] M7 remove obsolete native FAT export authority

---
 MainWindow.NativeFatExport.cs | 166 ----------------------------------
 1 file changed, 166 deletions(-)
 delete mode 100644 MainWindow.NativeFatExport.cs

diff --git a/MainWindow.NativeFatExport.cs b/MainWindow.NativeFatExport.cs
deleted file mode 100644
index 426cd18c8..000000000
--- a/MainWindow.NativeFatExport.cs
+++ /dev/null
@@ -1,166 +0,0 @@
-using System.Runtime.CompilerServices;
-using System.Windows;
-using System.Windows.Controls;
-using System.Windows.Threading;
-using ArIED61850Tester.Services;
-using Microsoft.Win32;
-
-namespace ArIED61850Tester;
-
-/// <summary>
-/// Native evidence export entry point. Export consumes the immutable report snapshot
-/// created from the already-loaded FAT state; it never creates a second IED session.
-/// </summary>
-public partial class MainWindow
-{
-    private DispatcherTimer? _nativeFatExportInstallRetry;
-    private Button? _nativeFatExportPdfButton;
-    private bool _nativeFatExportInstalled;
-
-    [ModuleInitializer]
-    internal static void RegisterNativeFatExport()
-    {
-        EventManager.RegisterClassHandler(
-            typeof(MainWindow),
-            FrameworkElement.LoadedEvent,
-            new RoutedEventHandler(NativeFatExport_MainWindowLoaded),
-            handledEventsToo: true);
-    }
-
-    private static void NativeFatExport_MainWindowLoaded(object sender, RoutedEventArgs e)
-    {
-        if (sender is not MainWindow window || window._nativeFatExportInstalled)
-            return;
-
-        window.Dispatcher.BeginInvoke(
-            DispatcherPriority.ApplicationIdle,
-            new Action(window.TryInstallNativeFatExport));
-    }
-
-    private void TryInstallNativeFatExport()
-    {
-        if (_nativeFatExportInstalled || !IsLoaded)
-            return;
-
-        if (!_nativeFatInstalled || _nativeFatSearchBox?.Parent is not WrapPanel toolbar)
-        {
-            _nativeFatExportInstallRetry ??= new DispatcherTimer(DispatcherPriority.ApplicationIdle)
-            {
-                Interval = TimeSpan.FromMilliseconds(190)
-            };
-            _nativeFatExportInstallRetry.Tick -= NativeFatExportInstallRetry_Tick;
-            _nativeFatExportInstallRetry.Tick += NativeFatExportInstallRetry_Tick;
-            _nativeFatExportInstallRetry.Start();
-            return;
-        }
-
-        _nativeFatExportInstallRetry?.Stop();
-        _nativeFatExportInstalled = true;
-        _nativeFatExportPdfButton = CreateNativeFatButton(
-            "Export PDF",
-            NativeFatExportPdf_Click,
-            "Export an immutable native FAT evidence PDF for the selected IED. Show historical controls whether historical signal rows are included.");
-
-        var historyIndex = _nativeFatShowHistoricalCheck == null
-            ? toolbar.Children.Count
-            : toolbar.Children.IndexOf(_nativeFatShowHistoricalCheck);
-        if (historyIndex < 0)
-            historyIndex = toolbar.Children.Count;
-        toolbar.Children.Insert(historyIndex, _nativeFatExportPdfButton);
-
-        Closed += NativeFatExport_MainWindowClosed;
-    }
-
-    private void NativeFatExportInstallRetry_Tick(object? sender, EventArgs e)
-    {
-        _nativeFatExportInstallRetry?.Stop();
-        TryInstallNativeFatExport();
-    }
-
-    private async void NativeFatExportPdf_Click(object sender, RoutedEventArgs e)
-    {
-        if (_nativeFatExportPdfButton == null)
-            return;
-
-        await EnsureNativeFatLoadedAsync(forceReconcile: false);
-        var device = SelectedDevice;
-        var state = _nativeFatCurrentState;
-        if (device == null || state == null ||
-            !state.DeviceId.Equals(device.DeviceId, StringComparison.OrdinalIgnoreCase))
-        {
-            SetNativeFatStatus("Select an IED with a loaded FAT state before exporting.");
-            return;
-        }
-
-        var includeHistorical = _nativeFatShowHistoricalCheck?.IsChecked == true;
-        var snapshot = NativeFatReportSnapshotBuilder.Build(device, state);
-        var dialog = new SaveFileDialog
-        {
-            Title = "Export ARSAS native FAT evidence PDF",
-            Filter = "PDF evidence report (*.pdf)|*.pdf",
-            FileName = $"{SafeNativeFatFileName(device.Name)}_FAT_{DateTime.Now:yyyyMMdd_HHmm}.pdf",
-            AddExtension = true,
-            DefaultExt = ".pdf",
-            OverwritePrompt = true
-        };
-        if (dialog.ShowDialog(this) != true)
-            return;
-
-        var previousContent = _nativeFatExportPdfButton.Content;
-        try
-        {
-            _nativeFatExportPdfButton.IsEnabled = false;
-            _nativeFatExportPdfButton.Content = "Exporting…";
-            SetNativeFatStatus("Saving current FAT state and building evidence PDF…");
-
-            // Persist the exact state used to construct the snapshot before delivering
-            // an external evidence file. The snapshot itself remains frozen thereafter.
-            await SaveNativeFatStateAsync(state);
-            await Task.Run(() => NativeFatPdfReportService.Save(
-                dialog.FileName,
-                snapshot,
-                includeHistorical));
-
-            SetNativeFatStatus($"PDF exported · {Path.GetFileName(dialog.FileName)}");
-            AddLog(
-                "INFO",
-                "Native FAT",
-                $"Native FAT PDF exported for {device.Name}: {dialog.FileName}" +
-                (includeHistorical ? " (historical included)" : string.Empty));
-        }
-        catch (Exception ex) when (ex is IOException or UnauthorizedAccessException or InvalidDataException or InvalidOperationException or ArgumentException)
-        {
-            AddLog("WARN", "Native FAT", $"PDF export failed: {ex.Message}");
-            SetNativeFatStatus("PDF export failed. Native FAT state remains saved.");
-            MessageBox.Show(
-                this,
-                ex.Message,
-                "Native FAT PDF export failed",
-                MessageBoxButton.OK,
-                MessageBoxImage.Error);
-        }
-        finally
-        {
-            _nativeFatExportPdfButton.Content = previousContent ?? "Export PDF";
-            _nativeFatExportPdfButton.IsEnabled = true;
-        }
-    }
-
-    private static string SafeNativeFatFileName(string? value)
-    {
-        var source = string.IsNullOrWhiteSpace(value) ? "IED" : value.Trim();
-        var invalid = Path.GetInvalidFileNameChars().ToHashSet();
-        var result = new string(source.Select(character => invalid.Contains(character) ? '_' : character).ToArray())
-            .Trim()
-            .Trim('.');
-        return string.IsNullOrWhiteSpace(result) ? "IED" : result;
-    }
-
-    private void NativeFatExport_MainWindowClosed(object? sender, EventArgs e)
-    {
-        _nativeFatExportInstallRetry?.Stop();
-        if (_nativeFatExportPdfButton != null)
-            _nativeFatExportPdfButton.Click -= NativeFatExportPdf_Click;
-        Closed -= NativeFatExport_MainWindowClosed;
-    }
-}

From a3972d525d3d46a9c9edd8388b0647ff203b3c40 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 15:44:54 +0700
Subject: [PATCH 59/84] M7 update canonical FAT shell regression contract

---
 ...ductionFatEngineeringTabRegressionTests.cs | 21 +++++++++++--------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/tests/ARSAS.Tests/ProductionFatEngineeringTabRegressionTests.cs b/tests/ARSAS.Tests/ProductionFatEngineeringTabRegressionTests.cs
index 91cc08816..c53331a23 100644
--- a/tests/ARSAS.Tests/ProductionFatEngineeringTabRegressionTests.cs
+++ b/tests/ARSAS.Tests/ProductionFatEngineeringTabRegressionTests.cs
@@ -48,7 +48,7 @@ public void SeventhFatDestination_IsCanonicalMainWindowSiblingWithOneNavigationO
     {
         var xaml = File.ReadAllText(FindRepoFile("MainWindow.xaml"));
         var mainSource = File.ReadAllText(FindRepoFile("MainWindow.xaml.cs"));
-        var nativeSource = File.ReadAllText(FindRepoFile("MainWindow.NativeFatWorkspace.cs"));
+        var bridgeSource = File.ReadAllText(FindRepoFile("MainWindow.NativeFatWorkspace.cs"));
         var productionSource = File.ReadAllText(FindRepoFile("MainWindow.ProductionFatTab.cs"));
         var repoRoot = FindRepoRoot();
 
@@ -60,16 +60,19 @@ public void SeventhFatDestination_IsCanonicalMainWindowSiblingWithOneNavigationO
         Assert.Contains("var cellWidth = contentWidth / 7d", mainSource, StringComparison.Ordinal);
         Assert.Contains("NavNativeFatButton", mainSource, StringComparison.Ordinal);
 
-        Assert.Contains("_nativeFatTab = NativeFatTab", nativeSource, StringComparison.Ordinal);
-        Assert.Contains("_nativeFatNavButton = NavNativeFatButton", nativeSource, StringComparison.Ordinal);
-        Assert.DoesNotContain("MainTabs.Items.Add(_nativeFatTab)", nativeSource, StringComparison.Ordinal);
-        Assert.DoesNotContain("InstallNativeFatNavigationButton", nativeSource, StringComparison.Ordinal);
-        Assert.DoesNotContain("Name = \"NavNativeFatButton\"", nativeSource, StringComparison.Ordinal);
-        Assert.DoesNotContain("var cellWidth = contentWidth / 7d", nativeSource, StringComparison.Ordinal);
+        Assert.Contains("private const int NativeFatWorkspaceIndex = 6", bridgeSource, StringComparison.Ordinal);
+        Assert.Contains("QueueNativeFatNavigationGeometry", bridgeSource, StringComparison.Ordinal);
+        Assert.DoesNotContain("_nativeFatTab", bridgeSource, StringComparison.Ordinal);
+        Assert.DoesNotContain("_nativeFatNavButton", bridgeSource, StringComparison.Ordinal);
+        Assert.DoesNotContain("BuildNativeFatWorkspaceContent", bridgeSource, StringComparison.Ordinal);
+        Assert.DoesNotContain("DataGrid", bridgeSource, StringComparison.Ordinal);
 
+        Assert.Contains("NativeFatTab.Content = BuildProductionFatPermanentHost();", productionSource, StringComparison.Ordinal);
+        Assert.Contains("NavNativeFatButton.ToolTip", productionSource, StringComparison.Ordinal);
         Assert.DoesNotContain("ProductionFatNavButton_Click", productionSource, StringComparison.Ordinal);
-        Assert.DoesNotContain("_nativeFatNavButton.Style =", productionSource, StringComparison.Ordinal);
-        Assert.DoesNotContain("_nativeFatNavButton.Click +=", productionSource, StringComparison.Ordinal);
+        Assert.DoesNotContain("_nativeFatInstalled", productionSource, StringComparison.Ordinal);
+        Assert.DoesNotContain("_nativeFatTab", productionSource, StringComparison.Ordinal);
+        Assert.DoesNotContain("_nativeFatNavButton", productionSource, StringComparison.Ordinal);
 
         Assert.False(
             File.Exists(Path.Combine(repoRoot, "MainWindow.ProductionFatNavigationParity.cs")),

From 166a6f61b1d6a83d9cb9e8d28ee18cd00e7d4530 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 15:45:13 +0700
Subject: [PATCH 60/84] M7 lock single production FAT authority regression

---
 .../ProductionFatM7CleanupRegressionTests.cs  | 42 ++++++++++++++++++-
 1 file changed, 40 insertions(+), 2 deletions(-)

diff --git a/tests/ARSAS.Tests/ProductionFatM7CleanupRegressionTests.cs b/tests/ARSAS.Tests/ProductionFatM7CleanupRegressionTests.cs
index 5b75b0369..7d5baf49b 100644
--- a/tests/ARSAS.Tests/ProductionFatM7CleanupRegressionTests.cs
+++ b/tests/ARSAS.Tests/ProductionFatM7CleanupRegressionTests.cs
@@ -3,23 +3,61 @@ namespace ARSAS.Tests;
 public sealed class ProductionFatM7CleanupRegressionTests
 {
     [Fact]
-    public void ObsoleteNativeSidePanelPreviewStack_IsNotASecondFatPreviewAuthority()
+    public void ObsoleteNativeFatRuntime_IsNotASecondProductionAuthority()
     {
         var repoRoot = FindRepoRoot();
+        var bridge = File.ReadAllText(Path.Combine(repoRoot, "MainWindow.NativeFatWorkspace.cs"));
+        var productionTab = File.ReadAllText(Path.Combine(repoRoot, "MainWindow.ProductionFatTab.cs"));
+
+        Assert.False(
+            File.Exists(Path.Combine(repoRoot, "MainWindow.NativeFatExport.cs")),
+            "The retired native FAT export must not return; production FAT owns report/export delivery.");
         Assert.False(
             File.Exists(Path.Combine(repoRoot, "MainWindow.NativeFatReportPreview.cs")),
             "The retired native FAT side-panel preview must not return. Production FAT owns one in-place report preview.");
         Assert.False(
             File.Exists(Path.Combine(repoRoot, "MainWindow.NativeFatHistoryInspector.cs")),
-            "The retired side-panel history inspector depended on the obsolete native preview and must not return as a second preview stack.");
+            "The retired side-panel history inspector must not return as a second FAT presentation stack.");
+
+        // MainWindow.NativeFatWorkspace.cs is now only a compatibility bridge for the
+        // canonical seventh shell slot. It must never regain its own FAT runtime/state.
+        Assert.Contains("private const int NativeFatWorkspaceIndex = 6", bridge, StringComparison.Ordinal);
+        Assert.Contains("QueueNativeFatNavigationGeometry", bridge, StringComparison.Ordinal);
+        Assert.DoesNotContain("DataGrid", bridge, StringComparison.Ordinal);
+        Assert.DoesNotContain("DispatcherTimer", bridge, StringComparison.Ordinal);
+        Assert.DoesNotContain("NativeFatStateStore", bridge, StringComparison.Ordinal);
+        Assert.DoesNotContain("NativeFatSignalRow", bridge, StringComparison.Ordinal);
+        Assert.DoesNotContain("NativeFatCapture", bridge, StringComparison.Ordinal);
+        Assert.DoesNotContain("SaveNativeFatStateAsync", bridge, StringComparison.Ordinal);
+        Assert.DoesNotContain("BuildNativeFatWorkspaceContent", bridge, StringComparison.Ordinal);
+        Assert.DoesNotContain("RegisterNativeFatWorkspace", bridge, StringComparison.Ordinal);
+
+        // Production FAT mounts directly into the canonical XAML slot. There must be no
+        // compatibility-field handshake with the retired native runtime.
+        Assert.Contains("NativeFatTab.Content = BuildProductionFatPermanentHost();", productionTab, StringComparison.Ordinal);
+        Assert.Contains("NativeFatTab.Content = surface;", productionTab, StringComparison.Ordinal);
+        Assert.Contains("NavNativeFatButton.ToolTip", productionTab, StringComparison.Ordinal);
+        Assert.DoesNotContain("_nativeFatInstalled", productionTab, StringComparison.Ordinal);
+        Assert.DoesNotContain("_nativeFatTab", productionTab, StringComparison.Ordinal);
+        Assert.DoesNotContain("_nativeFatNavButton", productionTab, StringComparison.Ordinal);
+        Assert.DoesNotContain("AttachNativeFatObservedDevice", productionTab, StringComparison.Ordinal);
+        Assert.DoesNotContain("NativeFat_MainWindowPropertyChanged", productionTab, StringComparison.Ordinal);
+        Assert.DoesNotContain("NativeFat_MainTabsSelectionChanged", productionTab, StringComparison.Ordinal);
+    }
 
+    [Fact]
+    public void ProductionReportPreviewAndExport_RemainSingleAuthority()
+    {
+        var repoRoot = FindRepoRoot();
         var productionPreview = File.ReadAllText(Path.Combine(repoRoot, "IoListTestingWindow.PrintPreview.cs"));
         var embeddedHost = File.ReadAllText(Path.Combine(repoRoot, "IoListTestingWindow.EmbeddedEngineeringHost.cs"));
+        var pdfService = File.ReadAllText(Path.Combine(repoRoot, "Services", "IoTesting", "IoFatPdfReportService.cs"));
 
         Assert.Contains("BuildPrintPreviewHost", productionPreview, StringComparison.Ordinal);
         Assert.Contains("IoFatReportPreviewDocumentBuilder.Build(scopedProject, draft)", productionPreview, StringComparison.Ordinal);
         Assert.Contains("InstallPerIedPrintPreview();", embeddedHost, StringComparison.Ordinal);
         Assert.Contains("_printPreviewToggle = WorkspacePreviewToggle;", embeddedHost, StringComparison.Ordinal);
+        Assert.Contains("BuildLayout", pdfService, StringComparison.Ordinal);
     }
 
     [Fact]

From 1044d6eb041fd963c3362a4f9cc66a04a828ca35 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 15:51:32 +0700
Subject: [PATCH 61/84] M7 remove retired native FAT explorer reconciler

---
 MainWindow.NativeFatExplorerSync.cs | 213 ----------------------------
 1 file changed, 213 deletions(-)
 delete mode 100644 MainWindow.NativeFatExplorerSync.cs

diff --git a/MainWindow.NativeFatExplorerSync.cs b/MainWindow.NativeFatExplorerSync.cs
deleted file mode 100644
index 8ea74646d..000000000
--- a/MainWindow.NativeFatExplorerSync.cs
+++ /dev/null
@@ -1,213 +0,0 @@
-using System.Collections.Specialized;
-using System.ComponentModel;
-using System.Runtime.CompilerServices;
-using System.Windows;
-using System.Windows.Controls;
-using System.Windows.Threading;
-using ArIED61850Tester.Models;
-
-namespace ArIED61850Tester;
-
-/// <summary>
-/// Keeps the native FAT projection aligned with the persistent IED Explorer's signal
-/// selection without turning FAT into a second signal database.
-///
-/// ObservableCollection changes were already reconciled by the first P2 slice. Explorer
-/// checkbox changes are different: SignalDefinition stays in the collection and only
-/// IsSelected changes. This bridge observes that property, marks the FAT scope dirty, and
-/// forces non-destructive reconciliation when FAT is visible (or the next time it opens).
-/// </summary>
-public partial class MainWindow
-{
-    private DispatcherTimer? _nativeFatExplorerSyncInstallRetry;
-    private DispatcherTimer? _nativeFatExplorerScopeTimer;
-    private Iec61850MonitorDevice? _nativeFatExplorerSyncDevice;
-    private readonly HashSet<SignalDefinition> _nativeFatExplorerObservedSignals = new();
-    private bool _nativeFatExplorerSyncAttached;
-    private bool _nativeFatExplorerScopeDirty;
-
-    [ModuleInitializer]
-    internal static void RegisterNativeFatExplorerSelectionSync()
-    {
-        EventManager.RegisterClassHandler(
-            typeof(MainWindow),
-            FrameworkElement.LoadedEvent,
-            new RoutedEventHandler(NativeFatExplorerSync_MainWindowLoaded),
-            handledEventsToo: true);
-    }
-
-    private static void NativeFatExplorerSync_MainWindowLoaded(object sender, RoutedEventArgs e)
-    {
-        if (sender is not MainWindow window || window._nativeFatExplorerSyncAttached)
-            return;
-
-        window.Dispatcher.BeginInvoke(
-            DispatcherPriority.ApplicationIdle,
-            new Action(window.TryAttachNativeFatExplorerSelectionSync));
-    }
-
-    private void TryAttachNativeFatExplorerSelectionSync()
-    {
-        if (_nativeFatExplorerSyncAttached || !IsLoaded)
-            return;
-
-        if (!_nativeFatInstalled)
-        {
-            _nativeFatExplorerSyncInstallRetry ??= new DispatcherTimer(DispatcherPriority.ApplicationIdle)
-            {
-                Interval = TimeSpan.FromMilliseconds(180)
-            };
-            _nativeFatExplorerSyncInstallRetry.Tick -= NativeFatExplorerSyncInstallRetry_Tick;
-            _nativeFatExplorerSyncInstallRetry.Tick += NativeFatExplorerSyncInstallRetry_Tick;
-            _nativeFatExplorerSyncInstallRetry.Start();
-            return;
-        }
-
-        _nativeFatExplorerSyncInstallRetry?.Stop();
-        _nativeFatExplorerSyncAttached = true;
-
-        _nativeFatExplorerScopeTimer = new DispatcherTimer(DispatcherPriority.Background)
-        {
-            Interval = TimeSpan.FromMilliseconds(180)
-        };
-        _nativeFatExplorerScopeTimer.Tick += NativeFatExplorerScopeTimer_Tick;
-
-        PropertyChanged += NativeFatExplorerSync_MainWindowPropertyChanged;
-        MainTabs.SelectionChanged += NativeFatExplorerSync_MainTabsSelectionChanged;
-        Closed += NativeFatExplorerSync_MainWindowClosed;
-        RebindNativeFatExplorerSignals(SelectedDevice);
-    }
-
-    private void NativeFatExplorerSyncInstallRetry_Tick(object? sender, EventArgs e)
-    {
-        _nativeFatExplorerSyncInstallRetry?.Stop();
-        TryAttachNativeFatExplorerSelectionSync();
-    }
-
-    private void NativeFatExplorerSync_MainWindowPropertyChanged(object? sender, PropertyChangedEventArgs e)
-    {
-        if (e.PropertyName != nameof(SelectedDevice))
-            return;
-
-        RebindNativeFatExplorerSignals(SelectedDevice);
-        MarkNativeFatExplorerScopeDirty();
-    }
-
-    private void RebindNativeFatExplorerSignals(Iec61850MonitorDevice? device)
-    {
-        if (ReferenceEquals(_nativeFatExplorerSyncDevice, device))
-        {
-            SyncNativeFatExplorerSignalSubscriptions();
-            return;
-        }
-
-        if (_nativeFatExplorerSyncDevice != null)
-            _nativeFatExplorerSyncDevice.Signals.CollectionChanged -= NativeFatExplorerSignals_CollectionChanged;
-
-        foreach (var signal in _nativeFatExplorerObservedSignals)
-            signal.PropertyChanged -= NativeFatExplorerSignal_PropertyChanged;
-        _nativeFatExplorerObservedSignals.Clear();
-
-        _nativeFatExplorerSyncDevice = device;
-        if (_nativeFatExplorerSyncDevice != null)
-        {
-            _nativeFatExplorerSyncDevice.Signals.CollectionChanged += NativeFatExplorerSignals_CollectionChanged;
-            SyncNativeFatExplorerSignalSubscriptions();
-        }
-    }
-
-    private void NativeFatExplorerSignals_CollectionChanged(object? sender, NotifyCollectionChangedEventArgs e)
-    {
-        SyncNativeFatExplorerSignalSubscriptions();
-        MarkNativeFatExplorerScopeDirty();
-    }
-
-    private void SyncNativeFatExplorerSignalSubscriptions()
-    {
-        var current = _nativeFatExplorerSyncDevice?.Signals.ToHashSet() ?? new HashSet<SignalDefinition>();
-
-        foreach (var signal in _nativeFatExplorerObservedSignals.Where(signal => !current.Contains(signal)).ToArray())
-        {
-            signal.PropertyChanged -= NativeFatExplorerSignal_PropertyChanged;
-            _nativeFatExplorerObservedSignals.Remove(signal);
-        }
-
-        foreach (var signal in current)
-        {
-            if (!_nativeFatExplorerObservedSignals.Add(signal))
-                continue;
-            signal.PropertyChanged += NativeFatExplorerSignal_PropertyChanged;
-        }
-    }
-
-    private void NativeFatExplorerSignal_PropertyChanged(object? sender, PropertyChangedEventArgs e)
-    {
-        // IsSelected is the Explorer membership authority. Value/quality/timestamp changes
-        // stay live-bound directly and must never trigger a full FAT reconciliation.
-        if (e.PropertyName == nameof(SignalDefinition.IsSelected))
-            MarkNativeFatExplorerScopeDirty();
-    }
-
-    private void MarkNativeFatExplorerScopeDirty()
-    {
-        _nativeFatExplorerScopeDirty = true;
-        if (MainTabs.SelectedIndex != NativeFatWorkspaceIndex)
-            return;
-
-        _nativeFatExplorerScopeTimer?.Stop();
-        _nativeFatExplorerScopeTimer?.Start();
-    }
-
-    private async void NativeFatExplorerScopeTimer_Tick(object? sender, EventArgs e)
-    {
-        _nativeFatExplorerScopeTimer?.Stop();
-        if (!_nativeFatExplorerScopeDirty || MainTabs.SelectedIndex != NativeFatWorkspaceIndex)
-            return;
-
-        await EnsureNativeFatLoadedAsync(forceReconcile: true);
-        _nativeFatExplorerScopeDirty = false;
-    }
-
-    private void NativeFatExplorerSync_MainTabsSelectionChanged(object sender, SelectionChangedEventArgs e)
-    {
-        if (!ReferenceEquals(e.Source, MainTabs) ||
-            MainTabs.SelectedIndex != NativeFatWorkspaceIndex ||
-            !_nativeFatExplorerScopeDirty)
-        {
-            return;
-        }
-
-        // The base P2 selection handler may have issued a fast non-forced load already.
-        // Re-run at ContextIdle with forceReconcile so checkbox changes made while another
-        // workspace was active are never hidden behind the current-state fast path.
-        Dispatcher.BeginInvoke(
-            DispatcherPriority.ContextIdle,
-            new Action(async () =>
-            {
-                if (MainTabs.SelectedIndex != NativeFatWorkspaceIndex || !_nativeFatExplorerScopeDirty)
-                    return;
-                await EnsureNativeFatLoadedAsync(forceReconcile: true);
-                _nativeFatExplorerScopeDirty = false;
-            }));
-    }
-
-    private void NativeFatExplorerSync_MainWindowClosed(object? sender, EventArgs e)
-    {
-        _nativeFatExplorerSyncInstallRetry?.Stop();
-        _nativeFatExplorerScopeTimer?.Stop();
-
-        PropertyChanged -= NativeFatExplorerSync_MainWindowPropertyChanged;
-        MainTabs.SelectionChanged -= NativeFatExplorerSync_MainTabsSelectionChanged;
-        Closed -= NativeFatExplorerSync_MainWindowClosed;
-
-        if (_nativeFatExplorerSyncDevice != null)
-            _nativeFatExplorerSyncDevice.Signals.CollectionChanged -= NativeFatExplorerSignals_CollectionChanged;
-        foreach (var signal in _nativeFatExplorerObservedSignals)
-            signal.PropertyChanged -= NativeFatExplorerSignal_PropertyChanged;
-
-        _nativeFatExplorerObservedSignals.Clear();
-        _nativeFatExplorerSyncDevice = null;
-        _nativeFatExplorerSyncAttached = false;
-        _nativeFatExplorerScopeDirty = false;
-    }
-}

From 8baacf5d7dc7b40665598aaca9b09d447fe873b0 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 15:51:39 +0700
Subject: [PATCH 62/84] M7 remove retired native FAT persistence safety runtime

---
 MainWindow.NativeFatPersistenceSafety.cs | 120 -----------------------
 1 file changed, 120 deletions(-)
 delete mode 100644 MainWindow.NativeFatPersistenceSafety.cs

diff --git a/MainWindow.NativeFatPersistenceSafety.cs b/MainWindow.NativeFatPersistenceSafety.cs
deleted file mode 100644
index 4f7e192b2..000000000
--- a/MainWindow.NativeFatPersistenceSafety.cs
+++ /dev/null
@@ -1,120 +0,0 @@
-using System.ComponentModel;
-using System.Runtime.CompilerServices;
-using System.Windows;
-using System.Windows.Threading;
-
-namespace ArIED61850Tester;
-
-/// <summary>
-/// Persistence durability guard for native FAT.
-///
-/// The normal 350 ms autosave debounce keeps multi-row operations cheap, but two short
-/// windows still need explicit protection:
-/// 1) the operator switches IED before the debounce fires; and
-/// 2) the operator closes ARSAS immediately after a capture/result change.
-///
-/// Native FAT caches one state object per stable IED. Flush inactive cached states after
-/// a SelectedDevice change and flush every cached state synchronously during Closing so
-/// evidence from the previously selected relay cannot be stranded in memory.
-/// </summary>
-public partial class MainWindow
-{
-    private bool _nativeFatPersistenceSafetyAttached;
-    private bool _nativeFatSwitchFlushQueued;
-
-    [ModuleInitializer]
-    internal static void RegisterNativeFatPersistenceSafety()
-    {
-        EventManager.RegisterClassHandler(
-            typeof(MainWindow),
-            FrameworkElement.LoadedEvent,
-            new RoutedEventHandler(NativeFatPersistenceSafety_MainWindowLoaded),
-            handledEventsToo: true);
-    }
-
-    private static void NativeFatPersistenceSafety_MainWindowLoaded(object sender, RoutedEventArgs e)
-    {
-        if (sender is not MainWindow window || window._nativeFatPersistenceSafetyAttached)
-            return;
-
-        window._nativeFatPersistenceSafetyAttached = true;
-        window.PropertyChanged += window.NativeFatPersistenceSafety_PropertyChanged;
-        window.Closing += window.NativeFatPersistenceSafety_Closing;
-        window.Closed += window.NativeFatPersistenceSafety_Closed;
-    }
-
-    private void NativeFatPersistenceSafety_PropertyChanged(object? sender, PropertyChangedEventArgs e)
-    {
-        if (e.PropertyName != nameof(SelectedDevice) || !_nativeFatInstalled || _nativeFatSwitchFlushQueued)
-            return;
-
-        // Let the normal SelectedDevice handler finish rebinding the workspace first.
-        // The previous state remains in _nativeFatStateCache, so a ContextIdle flush can
-        // save it without blocking the IED switch or relying on _nativeFatCurrentState.
-        _nativeFatSwitchFlushQueued = true;
-        Dispatcher.BeginInvoke(
-            DispatcherPriority.ContextIdle,
-            new Action(() =>
-            {
-                _nativeFatSwitchFlushQueued = false;
-                _ = NativeFatPersistenceSafety_FlushInactiveStatesAsync();
-            }));
-    }
-
-    private async Task NativeFatPersistenceSafety_FlushInactiveStatesAsync()
-    {
-        if (_nativeFatStateCache.Count == 0)
-            return;
-
-        var current = _nativeFatCurrentState;
-        var inactive = _nativeFatStateCache.Values
-            .Where(state => !ReferenceEquals(state, current))
-            .Distinct()
-            .ToArray();
-
-        foreach (var state in inactive)
-            await SaveNativeFatStateAsync(state);
-    }
-
-    private void NativeFatPersistenceSafety_Closing(object? sender, CancelEventArgs e)
-    {
-        _nativeFatSaveTimer?.Stop();
-
-        var states = _nativeFatStateCache.Values.Distinct().ToList();
-        if (_nativeFatCurrentState != null && !states.Contains(_nativeFatCurrentState))
-            states.Add(_nativeFatCurrentState);
-        if (states.Count == 0)
-            return;
-
-        foreach (var state in states)
-        {
-            try
-            {
-                // Intentionally bypass the UI save gate here. A debounced asynchronous
-                // save may currently own that gate and need the dispatcher for its
-                // continuation; waiting for the gate synchronously could deadlock Closing.
-                // NativeFatStateStore uses unique temp files + atomic replace, so a
-                // concurrent same-state flush is safe and never truncates the valid file.
-                _nativeFatStore.SaveAsync(state, CancellationToken.None).GetAwaiter().GetResult();
-            }
-            catch (Exception ex)
-            {
-                // Shutdown must remain possible. Any previous valid JSON is preserved;
-                // record the specific IED failure while diagnostics are still available.
-                AddLog(
-                    "WARN",
-                    "Native FAT",
-                    $"Final FAT persistence flush failed for {state.IedName}: {ex.Message}");
-            }
-        }
-    }
-
-    private void NativeFatPersistenceSafety_Closed(object? sender, EventArgs e)
-    {
-        PropertyChanged -= NativeFatPersistenceSafety_PropertyChanged;
-        Closing -= NativeFatPersistenceSafety_Closing;
-        Closed -= NativeFatPersistenceSafety_Closed;
-        _nativeFatPersistenceSafetyAttached = false;
-        _nativeFatSwitchFlushQueued = false;
-    }
-}

From 5269fed46415b56eb007af0b400abbfbcfd10aef Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 15:52:03 +0700
Subject: [PATCH 63/84] M7 guard retired native FAT runtime fragments

---
 tests/ARSAS.Tests/ProductionFatM7CleanupRegressionTests.cs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/tests/ARSAS.Tests/ProductionFatM7CleanupRegressionTests.cs b/tests/ARSAS.Tests/ProductionFatM7CleanupRegressionTests.cs
index 7d5baf49b..f0e993000 100644
--- a/tests/ARSAS.Tests/ProductionFatM7CleanupRegressionTests.cs
+++ b/tests/ARSAS.Tests/ProductionFatM7CleanupRegressionTests.cs
@@ -18,6 +18,12 @@ public void ObsoleteNativeFatRuntime_IsNotASecondProductionAuthority()
         Assert.False(
             File.Exists(Path.Combine(repoRoot, "MainWindow.NativeFatHistoryInspector.cs")),
             "The retired side-panel history inspector must not return as a second FAT presentation stack.");
+        Assert.False(
+            File.Exists(Path.Combine(repoRoot, "MainWindow.NativeFatExplorerSync.cs")),
+            "The retired native FAT Explorer reconciler must not return; Engineering selection and production FAT own synchronization.");
+        Assert.False(
+            File.Exists(Path.Combine(repoRoot, "MainWindow.NativeFatPersistenceSafety.cs")),
+            "The retired native FAT persistence runtime must not return; production FAT storage remains the persistence authority.");
 
         // MainWindow.NativeFatWorkspace.cs is now only a compatibility bridge for the
         // canonical seventh shell slot. It must never regain its own FAT runtime/state.

From 352883c1d41ca5f409ffe2f5c0908ad8d1c5df4f Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 15:57:20 +0700
Subject: [PATCH 64/84] M7 align M6 preview regression with canonical FAT tab
 authority

---
 .../ProductionFatM6ReportPreviewRegressionTests.cs        | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/tests/ARSAS.Tests/ProductionFatM6ReportPreviewRegressionTests.cs b/tests/ARSAS.Tests/ProductionFatM6ReportPreviewRegressionTests.cs
index 25ba7687c..2da47482c 100644
--- a/tests/ARSAS.Tests/ProductionFatM6ReportPreviewRegressionTests.cs
+++ b/tests/ARSAS.Tests/ProductionFatM6ReportPreviewRegressionTests.cs
@@ -18,9 +18,11 @@ public void EmbeddedFat_UsesExactProductionPreviewInsideTheSameCenter()
         Assert.Contains("_printPreviewToggle = WorkspacePreviewToggle;", embedded, StringComparison.Ordinal);
         Assert.Contains("DetachProductionFatCentralWorkspace", embedded, StringComparison.Ordinal);
 
-        // MainWindow hosts the exact detached production center. Explorer and Command Dock
-        // remain owned by the workstation shell; preview never replaces MainWindow itself.
-        Assert.Contains("_nativeFatTab.Content = surface;", productionTab, StringComparison.Ordinal);
+        // MainWindow hosts the exact detached production center in the canonical XAML FAT tab.
+        // Explorer and Command Dock remain owned by the workstation shell; preview never
+        // replaces MainWindow itself and no retired native FAT tab authority is recreated.
+        Assert.Contains("NativeFatTab.Content = surface;", productionTab, StringComparison.Ordinal);
+        Assert.DoesNotContain("_nativeFatTab.Content = surface;", productionTab, StringComparison.Ordinal);
         Assert.Contains("global Engineering IED Explorer and shared Command Dock remain authoritative", productionTab, StringComparison.Ordinal);
 
         var install = ExtractMethod(preview, "private void InstallPerIedPrintPreview()");

From bf0b93b2869125413bb20c402bd657acac95ea64 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 16:41:13 +0700
Subject: [PATCH 65/84] fix(FAT): stop background bootstrap from mutating
 Engineering acquisition

---
 MainWindow.ProductionFatEngineeringBootstrap.cs | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/MainWindow.ProductionFatEngineeringBootstrap.cs b/MainWindow.ProductionFatEngineeringBootstrap.cs
index bac287011..67f14f93e 100644
--- a/MainWindow.ProductionFatEngineeringBootstrap.cs
+++ b/MainWindow.ProductionFatEngineeringBootstrap.cs
@@ -38,7 +38,6 @@ private static void ProductionFatEngineeringBootstrap_Loaded(object sender, Rout
         window.MainTabs.SelectionChanged += window.ProductionFatEngineeringBootstrap_SelectionChanged;
         window.PropertyChanged += window.ProductionFatEngineeringBootstrap_PropertyChanged;
         window.Closed += window.ProductionFatEngineeringBootstrap_Closed;
-        window.QueueProductionFatEngineeringBootstrap();
     }
 
     private void ProductionFatEngineeringBootstrap_SelectionChanged(object sender, SelectionChangedEventArgs e)
@@ -50,19 +49,22 @@ private void ProductionFatEngineeringBootstrap_SelectionChanged(object sender, S
 
     private void ProductionFatEngineeringBootstrap_PropertyChanged(object? sender, PropertyChangedEventArgs e)
     {
-        if (e.PropertyName != nameof(SelectedDevice))
+        if (e.PropertyName != nameof(SelectedDevice) || MainTabs.SelectedIndex != NativeFatWorkspaceIndex)
             return;
 
         // A running production FAT session owns its latched IED. The normal embedded-host
         // selection bridge handles idle retargeting. Bootstrap is only needed before a FAT
-        // workspace exists.
+        // workspace exists and only while the operator is actually entering FAT.
         if (_productionFatWindow == null && _loadedIoFatWindow == null)
             QueueProductionFatEngineeringBootstrap();
     }
 
     private void QueueProductionFatEngineeringBootstrap()
     {
-        if (!_productionFatEngineeringBootstrapInstalled)
+        // FAT preparation must never run in the background while Engineering is connecting
+        // or monitoring. The shared Engineering acquisition session remains authoritative;
+        // clicking FAT is the only navigation event allowed to build the FAT projection.
+        if (!_productionFatEngineeringBootstrapInstalled || MainTabs.SelectedIndex != NativeFatWorkspaceIndex)
             return;
 
         Dispatcher.BeginInvoke(
@@ -73,6 +75,7 @@ private void QueueProductionFatEngineeringBootstrap()
     private async Task EnsureProductionFatFromEngineeringAsync()
     {
         if (_productionFatEngineeringBootstrapBusy ||
+            MainTabs.SelectedIndex != NativeFatWorkspaceIndex ||
             !ProductionFatTabReady)
         {
             return;
@@ -158,7 +161,7 @@ private async Task EnsureProductionFatFromEngineeringAsync()
                              ?? ResolveIoTestDevice(ied.IpAddress)
                              ?? ResolveIoTestDevice(ied.IedName);
                 if (device is not null)
-                    MarkSharedSelectionAuthority(device);
+                    PreserveSharedStaticDataSetAuthority(device);
             }
 
             launch.Workspace.ScheduleSave();

From f563aed02c4cedad63200a73882cb9e3d97d2f12 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 16:41:22 +0700
Subject: [PATCH 66/84] fix(FAT): preserve Engineering static DataSet authority

---
 MainWindow.SharedStaticDataSetAuthority.cs | 29 ++++++++++++++++++++++
 1 file changed, 29 insertions(+)
 create mode 100644 MainWindow.SharedStaticDataSetAuthority.cs

diff --git a/MainWindow.SharedStaticDataSetAuthority.cs b/MainWindow.SharedStaticDataSetAuthority.cs
new file mode 100644
index 000000000..f076810c1
--- /dev/null
+++ b/MainWindow.SharedStaticDataSetAuthority.cs
@@ -0,0 +1,29 @@
+using ArIED61850Tester.Models;
+using ArIED61850Tester.Services;
+
+namespace ArIED61850Tester;
+
+public partial class MainWindow
+{
+    /// <summary>
+    /// Reasserts the acquisition contract already chosen in Engineering when the FAT
+    /// projection is opened. FAT is a consumer of the shared static DataSet workspace;
+    /// it must never demote that workspace to Hybrid/MMS merely because a FAT session
+    /// was materialized.
+    /// </summary>
+    private void PreserveSharedStaticDataSetAuthority(Iec61850MonitorDevice device)
+    {
+        ArgumentNullException.ThrowIfNull(device);
+
+        Iec61850MonitoringModeRegistry.UseStaticDataSetReportOnly(device);
+        _sharedSclSelectionAuthorityDeviceIds.Add(device.DeviceId);
+        _sharedSclStaticDataSetAuthorityDeviceIds.Add(device.DeviceId);
+        SaveSignalSelectionMemory(device);
+        device.RefreshComputed();
+
+        AddLog(
+            "INFO",
+            "FAT",
+            $"Preserved Engineering Static DataSet report-only authority for {device.Name}; FAT did not enable Hybrid or cyclic MMS polling.");
+    }
+}

From f3c9f30b736a8e034b883a46992463d018c56025 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 16:41:53 +0700
Subject: [PATCH 67/84] fix(FAT): normalize hidden donor before WPF Show and
 fail visibly

---
 ...stTestingWindow.EmbeddedEngineeringHost.cs | 22 +++++++++++++------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/IoListTestingWindow.EmbeddedEngineeringHost.cs b/IoListTestingWindow.EmbeddedEngineeringHost.cs
index d5dfe0478..38a163cfb 100644
--- a/IoListTestingWindow.EmbeddedEngineeringHost.cs
+++ b/IoListTestingWindow.EmbeddedEngineeringHost.cs
@@ -30,9 +30,11 @@ internal static void RegisterEmbeddedEngineeringFatHost()
 
     internal void PrepareForEmbeddedEngineeringHost()
     {
-        // Must run before Window.Show(). A transparent/off-screen, non-activating donor
-        // cannot produce the historical black/blank compositor frame while its exact
-        // production center is being re-parented into MainWindow.
+        // WPF refuses Window.Show() when ShowActivated=false while WindowState=Maximized.
+        // The production FAT XAML historically starts maximized, therefore normalize the
+        // invisible donor BEFORE Show(). Its exact center is re-parented into MainWindow on
+        // Loaded; the donor itself never needs a maximized native HWND.
+        WindowState = WindowState.Normal;
         ShowActivated = false;
         ShowInTaskbar = false;
         Opacity = 0d;
@@ -75,14 +77,13 @@ private void TryMountIntoEngineering(MainWindow owner)
         {
             EnsureProductionFatPresentationForEmbeddedHost();
             DisableLegacyEmbeddedCommandPanel();
-            var surface = DetachProductionFatCentralWorkspace();
-            if (surface == null)
-                return;
+            var surface = DetachProductionFatCentralWorkspace()
+                          ?? throw new InvalidOperationException("Production FAT center could not be detached from its donor window.");
 
             _engineeringEmbeddedSurface = surface;
             _engineeringEmbeddedMounted = owner.MountProductionFatWorkspace(this, surface);
             if (!_engineeringEmbeddedMounted)
-                return;
+                throw new InvalidOperationException("Engineering FAT host rejected the production workspace surface.");
 
             // The central FAT view now belongs to MainWindow. Keep this Window loaded and
             // hidden because existing controller/session/event code is intentionally reused.
@@ -90,9 +91,16 @@ private void TryMountIntoEngineering(MainWindow owner)
         }
         catch (Exception ex)
         {
+            // Never leave an invisible off-screen donor as a silent blank FAT failure.
+            // Restore the historical standalone presentation so the operator has a usable
+            // production FAT surface and a visible diagnostic if embedding itself fails.
+            WindowState = WindowState.Maximized;
             Opacity = 1d;
             ShowInTaskbar = true;
             ShowActivated = true;
+            WindowStartupLocation = WindowStartupLocation.CenterOwner;
+            Left = double.NaN;
+            Top = double.NaN;
             MessageBox.Show(
                 owner,
                 $"ARSAS could not embed the production FAT workspace. The standalone FAT window will remain available.\n\n{ex.Message}",

From 883ec4a35a982aa1df57358bebf7be7948e25202 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 16:42:13 +0700
Subject: [PATCH 68/84] test(FAT): cover field regression for static authority
 and WPF donor Show

---
 ...uctionFatM2PermanentHostRegressionTests.cs | 86 +++++++++++++++++--
 1 file changed, 78 insertions(+), 8 deletions(-)

diff --git a/tests/ARSAS.Tests/ProductionFatM2PermanentHostRegressionTests.cs b/tests/ARSAS.Tests/ProductionFatM2PermanentHostRegressionTests.cs
index 75266cc0d..5f113b828 100644
--- a/tests/ARSAS.Tests/ProductionFatM2PermanentHostRegressionTests.cs
+++ b/tests/ARSAS.Tests/ProductionFatM2PermanentHostRegressionTests.cs
@@ -16,19 +16,43 @@ public void FatTab_IsPermanentHost_NotLauncherOrAlternateOpenSclWorkflow()
     }
 
     [Fact]
-    public void EngineeringStaticDataSet_PrewarmIsIndependentOfFatTabSelection()
+    public void EngineeringStaticDataSet_FatBootstrapIsNavigationGated()
     {
         var bootstrap = Read("MainWindow.ProductionFatEngineeringBootstrap.cs");
-        var shared = Read("MainWindow.SharedSclWorkspace.cs");
 
-        Assert.Contains("e.PropertyName != nameof(SelectedDevice)", bootstrap, StringComparison.Ordinal);
-        Assert.Contains("QueueProductionFatEngineeringBootstrap();", shared, StringComparison.Ordinal);
-        Assert.DoesNotContain("_productionFatEngineeringBootstrapBusy ||\n            MainTabs.SelectedIndex != NativeFatWorkspaceIndex", bootstrap, StringComparison.Ordinal);
-        Assert.DoesNotContain("_productionFatEngineeringBootstrapInstalled || MainTabs.SelectedIndex != NativeFatWorkspaceIndex", bootstrap, StringComparison.Ordinal);
+        Assert.DoesNotContain(
+            "window.QueueProductionFatEngineeringBootstrap();\n    }\n\n    private void ProductionFatEngineeringBootstrap_SelectionChanged",
+            bootstrap,
+            StringComparison.Ordinal);
+        Assert.Contains(
+            "e.PropertyName != nameof(SelectedDevice) || MainTabs.SelectedIndex != NativeFatWorkspaceIndex",
+            bootstrap,
+            StringComparison.Ordinal);
+        Assert.Contains(
+            "!_productionFatEngineeringBootstrapInstalled || MainTabs.SelectedIndex != NativeFatWorkspaceIndex",
+            bootstrap,
+            StringComparison.Ordinal);
+        Assert.Contains(
+            "_productionFatEngineeringBootstrapBusy ||\n            MainTabs.SelectedIndex != NativeFatWorkspaceIndex",
+            bootstrap,
+            StringComparison.Ordinal);
     }
 
     [Fact]
-    public void EmbeddedDonor_IsPreparedBeforeShow_AndMainWindowStaysVisible()
+    public void AutomaticFatBootstrap_PreservesStaticReportOnlyAuthority()
+    {
+        var bootstrap = Read("MainWindow.ProductionFatEngineeringBootstrap.cs");
+        var authority = Read("MainWindow.SharedStaticDataSetAuthority.cs");
+
+        Assert.Contains("PreserveSharedStaticDataSetAuthority(device);", bootstrap, StringComparison.Ordinal);
+        Assert.DoesNotContain("MarkSharedSelectionAuthority(device);", bootstrap, StringComparison.Ordinal);
+        Assert.Contains("Iec61850MonitoringModeRegistry.UseStaticDataSetReportOnly(device);", authority, StringComparison.Ordinal);
+        Assert.DoesNotContain("UseHybrid", authority, StringComparison.Ordinal);
+        Assert.Contains("_sharedSclStaticDataSetAuthorityDeviceIds.Add(device.DeviceId);", authority, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void EmbeddedDonor_IsPreparedBeforeShow_AndNormalizesIllegalMaximizedState()
     {
         var launch = Read("MainWindow.IoTesting.cs");
         var host = Read("IoListTestingWindow.EmbeddedEngineeringHost.cs");
@@ -38,9 +62,13 @@ public void EmbeddedDonor_IsPreparedBeforeShow_AndMainWindowStaysVisible()
         var show = launch.IndexOf("window.Show();", StringComparison.Ordinal);
         Assert.True(prepare >= 0 && show > prepare, "Donor visibility must be prepared before Window.Show().");
         Assert.Contains("if (!ProductionFatTabReady)\n            Hide();", launch, StringComparison.Ordinal);
+
+        var normal = host.IndexOf("WindowState = WindowState.Normal;", StringComparison.Ordinal);
+        var nonActivating = host.IndexOf("ShowActivated = false;", StringComparison.Ordinal);
+        Assert.True(normal >= 0 && nonActivating > normal,
+            "The hidden donor must leave Maximized state before ShowActivated=false is used.");
         Assert.Contains("Left = -32000d", host, StringComparison.Ordinal);
         Assert.Contains("Opacity = 0d", host, StringComparison.Ordinal);
-        Assert.Contains("ShowActivated = false", host, StringComparison.Ordinal);
         Assert.Contains("ShowInTaskbar = false", host, StringComparison.Ordinal);
 
         Assert.DoesNotContain("MainTabs.SelectedIndex = NativeFatWorkspaceIndex", tab, StringComparison.Ordinal);
@@ -48,6 +76,46 @@ public void EmbeddedDonor_IsPreparedBeforeShow_AndMainWindowStaysVisible()
         Assert.DoesNotContain("if (!IsVisible)\n            Show();", tab, StringComparison.Ordinal);
     }
 
+    [Fact]
+    public void HiddenNonActivatingWpfDonor_CanShowAfterStateNormalization()
+    {
+        if (!OperatingSystem.IsWindows())
+            return;
+
+        Exception? failure = null;
+        var completed = false;
+        var thread = new Thread(() =>
+        {
+            try
+            {
+                var window = new System.Windows.Window
+                {
+                    WindowState = System.Windows.WindowState.Normal,
+                    ShowActivated = false,
+                    ShowInTaskbar = false,
+                    Opacity = 0d,
+                    WindowStartupLocation = System.Windows.WindowStartupLocation.Manual,
+                    Left = -32000d,
+                    Top = -32000d
+                };
+
+                window.Show();
+                window.Close();
+                completed = true;
+            }
+            catch (Exception ex)
+            {
+                failure = ex;
+            }
+        });
+
+        thread.SetApartmentState(ApartmentState.STA);
+        thread.Start();
+        Assert.True(thread.Join(TimeSpan.FromSeconds(8)), "WPF donor Show/Close timed out.");
+        Assert.Null(failure);
+        Assert.True(completed);
+    }
+
     [Fact]
     public void EmbeddedSurface_RemainsExactProductionGridAndPreviewSource()
     {
@@ -57,6 +125,8 @@ public void EmbeddedSurface_RemainsExactProductionGridAndPreviewSource()
         Assert.Contains("InstallPerIedPrintPreview();", host, StringComparison.Ordinal);
         Assert.Contains("DetachProductionFatCentralWorkspace()", host, StringComparison.Ordinal);
         Assert.Contains("owner.MountProductionFatWorkspace(this, surface)", host, StringComparison.Ordinal);
+        Assert.Contains("throw new InvalidOperationException(\"Production FAT center could not be detached", host, StringComparison.Ordinal);
+        Assert.Contains("WindowState = WindowState.Maximized;", host, StringComparison.Ordinal);
     }
 
     private static string Read(string relativePath)

From fac95889a31c5bd89b19c36d6015e9468dfb9e92 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 16:43:12 +0700
Subject: [PATCH 69/84] perf(FAT): keep static authority reassertion passive

---
 MainWindow.SharedStaticDataSetAuthority.cs | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/MainWindow.SharedStaticDataSetAuthority.cs b/MainWindow.SharedStaticDataSetAuthority.cs
index f076810c1..bfeae00ab 100644
--- a/MainWindow.SharedStaticDataSetAuthority.cs
+++ b/MainWindow.SharedStaticDataSetAuthority.cs
@@ -7,9 +7,9 @@ public partial class MainWindow
 {
     /// <summary>
     /// Reasserts the acquisition contract already chosen in Engineering when the FAT
-    /// projection is opened. FAT is a consumer of the shared static DataSet workspace;
-    /// it must never demote that workspace to Hybrid/MMS merely because a FAT session
-    /// was materialized.
+    /// projection is opened. FAT is a passive consumer of the shared static DataSet
+    /// workspace; this method deliberately performs no signal reselection, persistence,
+    /// reconnect, discovery, or RefreshComputed work.
     /// </summary>
     private void PreserveSharedStaticDataSetAuthority(Iec61850MonitorDevice device)
     {
@@ -18,12 +18,10 @@ private void PreserveSharedStaticDataSetAuthority(Iec61850MonitorDevice device)
         Iec61850MonitoringModeRegistry.UseStaticDataSetReportOnly(device);
         _sharedSclSelectionAuthorityDeviceIds.Add(device.DeviceId);
         _sharedSclStaticDataSetAuthorityDeviceIds.Add(device.DeviceId);
-        SaveSignalSelectionMemory(device);
-        device.RefreshComputed();
 
         AddLog(
             "INFO",
             "FAT",
-            $"Preserved Engineering Static DataSet report-only authority for {device.Name}; FAT did not enable Hybrid or cyclic MMS polling.");
+            $"Preserved Engineering Static DataSet report-only authority for {device.Name}; FAT did not reconnect, enable Hybrid, or start cyclic MMS polling.");
     }
 }

From 9d2baeb1e7f745b3e941d68743d05da8af679736 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 17:11:12 +0700
Subject: [PATCH 70/84] Keep embedded Static DataSet FAT off the legacy 250ms
 polling path

---
 MainWindow.ProductionFatFieldPerformance.cs | 75 +++++++++++++++++++++
 1 file changed, 75 insertions(+)
 create mode 100644 MainWindow.ProductionFatFieldPerformance.cs

diff --git a/MainWindow.ProductionFatFieldPerformance.cs b/MainWindow.ProductionFatFieldPerformance.cs
new file mode 100644
index 000000000..ffbfa80ab
--- /dev/null
+++ b/MainWindow.ProductionFatFieldPerformance.cs
@@ -0,0 +1,75 @@
+using System.Runtime.CompilerServices;
+using System.Windows;
+using System.Windows.Threading;
+
+namespace ArIED61850Tester;
+
+/// <summary>
+/// Field guard for the embedded Static DataSet FAT path.
+/// The legacy standalone FAT workspace temporarily tightened MainWindow polling to 250 ms.
+/// That is unnecessary when FAT is consuming the already-running Engineering Static RCB/URCB
+/// report-only session, and keeping it active after embedding adds avoidable UI/runtime load
+/// while the operator navigates to other Engineering tabs.
+/// </summary>
+public partial class MainWindow
+{
+    [ModuleInitializer]
+    internal static void RegisterProductionFatFieldPerformanceGuard()
+    {
+        EventManager.RegisterClassHandler(
+            typeof(IoListTestingWindow),
+            FrameworkElement.LoadedEvent,
+            new RoutedEventHandler(ProductionFatFieldPerformance_IoWindowLoaded),
+            handledEventsToo: true);
+    }
+
+    private static void ProductionFatFieldPerformance_IoWindowLoaded(object sender, RoutedEventArgs e)
+    {
+        if (sender is not IoListTestingWindow window ||
+            !ReferenceEquals(e.OriginalSource, window) ||
+            window.Owner is not MainWindow owner ||
+            !owner.ProductionFatTabReady)
+        {
+            return;
+        }
+
+        // EmbeddedEngineeringHost mounts at Loaded priority. Run after that short operation,
+        // then release only the legacy cyclic-polling acceleration. FAT evidence continues to
+        // arrive from the exact shared Engineering report session and Runtime.PointUpdated.
+        owner.Dispatcher.BeginInvoke(
+            DispatcherPriority.ContextIdle,
+            new Action(() => owner.ReleaseLegacyPollingOverrideForStaticEmbeddedFat(window)));
+    }
+
+    private void ReleaseLegacyPollingOverrideForStaticEmbeddedFat(IoListTestingWindow window)
+    {
+        if (!window.IsLoaded ||
+            !ReferenceEquals(_loadedIoFatWindow, window) ||
+            !_pollingIntervalBeforeIoFat.HasValue)
+        {
+            return;
+        }
+
+        var liveDevices = window.Project.Ieds
+            .Select(ied => ResolveIoTestDevice(ied.LiveDeviceId)
+                           ?? ResolveIoTestDevice(ied.IpAddress)
+                           ?? ResolveIoTestDevice(ied.IedName))
+            .Where(device => device is not null)
+            .Distinct()
+            .ToArray();
+
+        // Workbook/manual FAT can still legitimately use the legacy faster polling cadence.
+        // Automatic Engineering FAT must not: every participating live IED must already own
+        // Static DataSet report-only authority before this override is released.
+        if (liveDevices.Length == 0 || liveDevices.Any(device => !IsSharedStaticDataSetAuthority(device!)))
+            return;
+
+        PollingIntervalMs = _pollingIntervalBeforeIoFat.Value;
+        _pollingIntervalBeforeIoFat = null;
+
+        AddLog(
+            "INFO",
+            "FAT",
+            $"Embedded Static DataSet FAT preserved Engineering polling cadence ({PollingIntervalMs} ms); no cyclic MMS acceleration remains active.");
+    }
+}

From 9275a5470dd39200ba7854505ccc653021d80819 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Thu, 10 Sep 2026 17:11:24 +0700
Subject: [PATCH 71/84] Add regression coverage for embedded FAT polling
 isolation

---
 ...ctionFatFieldPerformanceRegressionTests.cs | 46 +++++++++++++++++++
 1 file changed, 46 insertions(+)
 create mode 100644 tests/ARSAS.Tests/ProductionFatFieldPerformanceRegressionTests.cs

diff --git a/tests/ARSAS.Tests/ProductionFatFieldPerformanceRegressionTests.cs b/tests/ARSAS.Tests/ProductionFatFieldPerformanceRegressionTests.cs
new file mode 100644
index 000000000..f6fe6b3c4
--- /dev/null
+++ b/tests/ARSAS.Tests/ProductionFatFieldPerformanceRegressionTests.cs
@@ -0,0 +1,46 @@
+namespace ARSAS.Tests;
+
+public sealed class ProductionFatFieldPerformanceRegressionTests
+{
+    [Fact]
+    public void EmbeddedStaticDataSetFat_ReleasesLegacy250msPollingOverride()
+    {
+        var source = Read("MainWindow.ProductionFatFieldPerformance.cs");
+
+        Assert.Contains("ReleaseLegacyPollingOverrideForStaticEmbeddedFat", source, StringComparison.Ordinal);
+        Assert.Contains("IsSharedStaticDataSetAuthority", source, StringComparison.Ordinal);
+        Assert.Contains("PollingIntervalMs = _pollingIntervalBeforeIoFat.Value;", source, StringComparison.Ordinal);
+        Assert.Contains("_pollingIntervalBeforeIoFat = null;", source, StringComparison.Ordinal);
+        Assert.DoesNotContain("UseHybrid", source, StringComparison.Ordinal);
+        Assert.DoesNotContain("MMS polling", source, StringComparison.OrdinalIgnoreCase);
+    }
+
+    [Fact]
+    public void ManualOrWorkbookFat_DoesNotLoseLegacyPollingCadence()
+    {
+        var source = Read("MainWindow.ProductionFatFieldPerformance.cs");
+
+        Assert.Contains(
+            "liveDevices.Any(device => !IsSharedStaticDataSetAuthority(device!))",
+            source,
+            StringComparison.Ordinal);
+        Assert.Contains("return;", source, StringComparison.Ordinal);
+    }
+
+    private static string Read(string relativePath)
+        => File.ReadAllText(Path.Combine(FindRepoRoot(), relativePath)).Replace("\r\n", "\n", StringComparison.Ordinal);
+
+    private static string FindRepoRoot()
+    {
+        DirectoryInfo? directory = new(AppContext.BaseDirectory);
+        while (directory != null)
+        {
+            if (File.Exists(Path.Combine(directory.FullName, "MainWindow.xaml")) &&
+                Directory.Exists(Path.Combine(directory.FullName, "tests", "ARSAS.Tests")))
+                return directory.FullName;
+            directory = directory.Parent;
+        }
+
+        throw new DirectoryNotFoundException("Could not locate repository root.");
+    }
+}

From 87ab15606b9cc93445f80bda8f7dcd7123497f97 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Fri, 11 Sep 2026 14:49:14 +0700
Subject: [PATCH 72/84] fix(fat): canonicalize Engineering workspace projection

---
 ...atEngineeringWorkspaceProjectionService.cs | 103 +++++++++++++++---
 1 file changed, 89 insertions(+), 14 deletions(-)

diff --git a/Services/IoTesting/IoFatEngineeringWorkspaceProjectionService.cs b/Services/IoTesting/IoFatEngineeringWorkspaceProjectionService.cs
index d6c9bc89c..7c5efe44d 100644
--- a/Services/IoTesting/IoFatEngineeringWorkspaceProjectionService.cs
+++ b/Services/IoTesting/IoFatEngineeringWorkspaceProjectionService.cs
@@ -36,12 +36,16 @@ public static async Task<IoFatEngineeringWorkspaceProjection> BuildAsync(
                 "No Engineering IED has an already-parsed SCL workspace with static DataSet members and source provenance.");
         }
 
-        var sourceInputs = usable
+        // Describe every candidate source once so conflicting Engineering authorities are
+        // detected before canonicalization. The resulting canonical source set is then used
+        // for the FAT projection/staging path so duplicate Explorer entries do not multiply
+        // static DataSet rows or repeat downstream workspace work.
+        var candidateSourceInputs = usable
             .Select(device => Path.GetFullPath(device.SclSourcePath))
             .Distinct(StringComparer.OrdinalIgnoreCase)
             .Select(path => new IoFatSourceInput(path, IoFatSourceKinds.Scl))
             .ToArray();
-        var described = await IoFatSourceWorkspaceService.DescribeAsync(sourceInputs, cancellationToken)
+        var described = await IoFatSourceWorkspaceService.DescribeAsync(candidateSourceInputs, cancellationToken)
             .ConfigureAwait(false);
         var descriptorByPath = described.ToDictionary(
             item => Path.GetFullPath(item.OriginalPath),
@@ -62,7 +66,14 @@ public static async Task<IoFatEngineeringWorkspaceProjection> BuildAsync(
             }
         }
 
-        var workspaceSources = usable
+        var canonicalDevices = CanonicalizeEngineeringDevices(usable, descriptorByPath);
+        var sourceInputs = canonicalDevices
+            .Select(device => Path.GetFullPath(device.SclSourcePath))
+            .Distinct(StringComparer.OrdinalIgnoreCase)
+            .Select(path => new IoFatSourceInput(path, IoFatSourceKinds.Scl))
+            .ToArray();
+
+        var workspaceSources = canonicalDevices
             .Select(device =>
             {
                 var descriptor = descriptorByPath[Path.GetFullPath(device.SclSourcePath)];
@@ -74,14 +85,15 @@ public static async Task<IoFatEngineeringWorkspaceProjection> BuildAsync(
             .ToArray();
         var verification = FatSclWorkspaceImportService.Import(workspaceSources).Project;
 
-        var deviceByWorkspace = usable
-            .GroupBy(device => WorkspaceIdentity(device.SclWorkspace!), StringComparer.OrdinalIgnoreCase)
-            .ToDictionary(group => group.Key, group => group.First(), StringComparer.OrdinalIgnoreCase);
-        var descriptorByWorkspace = usable
-            .GroupBy(device => WorkspaceIdentity(device.SclWorkspace!), StringComparer.OrdinalIgnoreCase)
+        var deviceByWorkspace = canonicalDevices
+            .ToDictionary(
+                device => WorkspaceIdentity(device.SclWorkspace!),
+                device => device,
+                StringComparer.OrdinalIgnoreCase);
+        var descriptorByWorkspace = canonicalDevices
             .ToDictionary(
-                group => group.Key,
-                group => descriptorByPath[Path.GetFullPath(group.First().SclSourcePath)],
+                device => WorkspaceIdentity(device.SclWorkspace!),
+                device => descriptorByPath[Path.GetFullPath(device.SclSourcePath)],
                 StringComparer.OrdinalIgnoreCase);
 
         var plans = new List<IoTestIedPlan>();
@@ -120,8 +132,8 @@ public static async Task<IoFatEngineeringWorkspaceProjection> BuildAsync(
             plans.Add(plan);
         }
 
-        var sourceDescriptors = described
-            .Select(item => item.Source)
+        var sourceDescriptors = canonicalDevices
+            .Select(device => descriptorByPath[Path.GetFullPath(device.SclSourcePath)])
             .GroupBy(source => source.SourceId, StringComparer.OrdinalIgnoreCase)
             .Select(group => group.First())
             .OrderBy(source => source.SourceId, StringComparer.Ordinal)
@@ -144,7 +156,7 @@ public static async Task<IoFatEngineeringWorkspaceProjection> BuildAsync(
         project.SetSources(sourceDescriptors, sourceFingerprint);
         project.InitializeRuntimeNotifications();
 
-        var staticMemberCount = usable.Sum(device =>
+        var staticMemberCount = canonicalDevices.Sum(device =>
             device.SclWorkspace!.DesignModel.DataSets.Sum(dataSet => dataSet.Members.Count));
         if (project.SignalCount != verification.Signals.Count || project.SignalCount != staticMemberCount)
         {
@@ -155,7 +167,70 @@ public static async Task<IoFatEngineeringWorkspaceProjection> BuildAsync(
         return new IoFatEngineeringWorkspaceProjection(
             project,
             sourceInputs,
-            usable.Select(device => device.SclWorkspace!).ToArray());
+            canonicalDevices.Select(device => device.SclWorkspace!).ToArray());
+    }
+
+    private static IReadOnlyList<Iec61850MonitorDevice> CanonicalizeEngineeringDevices(
+        IReadOnlyCollection<Iec61850MonitorDevice> devices,
+        IReadOnlyDictionary<string, IoFatSourceDescriptor> descriptorByPath)
+    {
+        var canonical = new List<Iec61850MonitorDevice>();
+        foreach (var identityGroup in devices
+                     .GroupBy(device => WorkspaceIdentity(device.SclWorkspace!), StringComparer.OrdinalIgnoreCase)
+                     .OrderBy(group => group.Key, StringComparer.OrdinalIgnoreCase))
+        {
+            var candidates = identityGroup
+                .Select(device =>
+                {
+                    var path = Path.GetFullPath(device.SclSourcePath);
+                    return new
+                    {
+                        Device = device,
+                        Path = path,
+                        Descriptor = descriptorByPath[path]
+                    };
+                })
+                .ToArray();
+
+            var distinctHashes = candidates
+                .Select(candidate => candidate.Descriptor.Sha256)
+                .Distinct(StringComparer.OrdinalIgnoreCase)
+                .ToArray();
+            if (distinctHashes.Length > 1)
+            {
+                throw new InvalidDataException(
+                    $"Conflicting Engineering SCL sources define the same IED/AccessPoint '{identityGroup.Key}'. " +
+                    "FAT will not silently merge competing static DataSet authorities.");
+            }
+
+            var distinctEndpoints = candidates
+                .Select(candidate => candidate.Device.IpAddress?.Trim() ?? string.Empty)
+                .Where(endpoint => !string.IsNullOrWhiteSpace(endpoint))
+                .Distinct(StringComparer.OrdinalIgnoreCase)
+                .ToArray();
+            if (distinctEndpoints.Length > 1)
+            {
+                throw new InvalidDataException(
+                    $"Engineering exposes IED/AccessPoint '{identityGroup.Key}' through multiple endpoints ({string.Join(", ", distinctEndpoints)}). " +
+                    "FAT will not guess which physical IED owns the evidence session.");
+            }
+
+            // Exact same-content duplicates are already harmless according to the lower SCL
+            // importer contract. Collapse them here as well so projection counts, runtime
+            // workspaces and staged source files all share one canonical authority. Prefer the
+            // currently monitoring/connected Engineering device so FAT remains attached to the
+            // live session that the operator is already using.
+            var selected = candidates
+                .OrderByDescending(candidate => candidate.Device.IsMonitoring)
+                .ThenByDescending(candidate => candidate.Device.IsConnected)
+                .ThenBy(candidate => candidate.Descriptor.FileName, StringComparer.OrdinalIgnoreCase)
+                .ThenBy(candidate => candidate.Path, StringComparer.OrdinalIgnoreCase)
+                .ThenBy(candidate => candidate.Device.DeviceId, StringComparer.OrdinalIgnoreCase)
+                .First();
+            canonical.Add(selected.Device);
+        }
+
+        return canonical;
     }
 
     private static IoTestPointPlan ToPointPlan(

From bb83b3e4e41994e286fcd50a3875a6afb57f1487 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Fri, 11 Sep 2026 14:49:41 +0700
Subject: [PATCH 73/84] fix(fat): render permanent loading shell before first
 FAT frame

---
 MainWindow.ProductionFatTab.cs | 88 ++++++++++++++++++++++++++++------
 1 file changed, 74 insertions(+), 14 deletions(-)

diff --git a/MainWindow.ProductionFatTab.cs b/MainWindow.ProductionFatTab.cs
index bc464d5d2..f09a3ae39 100644
--- a/MainWindow.ProductionFatTab.cs
+++ b/MainWindow.ProductionFatTab.cs
@@ -36,9 +36,10 @@ private static void ProductionFatTab_MainWindowLoaded(object sender, RoutedEvent
         if (sender is not MainWindow window || window._productionFatTabInstalled)
             return;
 
-        window.Dispatcher.BeginInvoke(
-            DispatcherPriority.ApplicationIdle,
-            new Action(window.TryInstallProductionFatTabPivot));
+        // MainWindow.Loaded runs after XAML has materialized the canonical seventh tab but
+        // before the first normal render. Install the permanent FAT shell immediately so the
+        // operator never sees an empty/black seventh workspace while idle-dispatcher work waits.
+        window.TryInstallProductionFatTabPivot();
     }
 
     private void TryInstallProductionFatTabPivot()
@@ -51,9 +52,9 @@ private void TryInstallProductionFatTabPivot()
         if (MainTabs.Items.Count <= NativeFatWorkspaceIndex ||
             !ReferenceEquals(MainTabs.Items[NativeFatWorkspaceIndex], NativeFatTab))
         {
-            _productionFatInstallRetry ??= new DispatcherTimer(DispatcherPriority.ApplicationIdle)
+            _productionFatInstallRetry ??= new DispatcherTimer(DispatcherPriority.Loaded)
             {
-                Interval = TimeSpan.FromMilliseconds(120)
+                Interval = TimeSpan.FromMilliseconds(60)
             };
             _productionFatInstallRetry.Tick -= ProductionFatInstallRetry_Tick;
             _productionFatInstallRetry.Tick += ProductionFatInstallRetry_Tick;
@@ -65,8 +66,8 @@ private void TryInstallProductionFatTabPivot()
         _productionFatTabInstalled = true;
         NativeFatTab.Content = BuildProductionFatPermanentHost();
 
-        // Prewarm as soon as the canonical host exists. A valid Engineering SCL/DataSet
-        // can prepare the exact production surface before the operator first opens FAT.
+        // Bootstrap remains navigation-gated. Queueing here is harmless because the
+        // Engineering bootstrap itself refuses to build FAT unless the FAT tab is active.
         QueueProductionFatEngineeringBootstrap();
 
         // MainWindow.xaml owns both style and click routing for the seventh nav button.
@@ -85,22 +86,81 @@ private void ProductionFatInstallRetry_Tick(object? sender, EventArgs e)
         TryInstallProductionFatTabPivot();
     }
 
-    private FrameworkElement BuildProductionFatPermanentHost()
+    private FrameworkElement BuildProductionFatPermanentHost(
+        string? statusText = null,
+        bool isBusy = false)
     {
-        // Stable shell slot, never a launcher or alternate FAT workflow. With a valid
-        // Engineering static DataSet this is replaced by the exact production FAT surface.
         var root = new Grid { Margin = new Thickness(0) };
-        root.Children.Add(new TextBlock
+        var card = new Border
         {
-            Text = "FAT · awaiting an Engineering IED with static DataSet scope",
-            FontSize = 12,
-            Foreground = TryFindResource("Muted") as Brush ?? Brushes.DimGray,
+            MaxWidth = 520,
+            Padding = new Thickness(28, 24, 28, 22),
+            CornerRadius = new CornerRadius(18),
+            Background = TryFindResource("CardBackground") as Brush ?? Brushes.White,
+            BorderBrush = TryFindResource("CardBorder") as Brush ?? new SolidColorBrush(Color.FromRgb(220, 228, 239)),
+            BorderThickness = new Thickness(1),
             HorizontalAlignment = HorizontalAlignment.Center,
             VerticalAlignment = VerticalAlignment.Center
+        };
+        var panel = new StackPanel
+        {
+            HorizontalAlignment = HorizontalAlignment.Stretch
+        };
+        panel.Children.Add(new TextBlock
+        {
+            Text = "IEC 61850 FAT",
+            FontSize = 11,
+            FontWeight = FontWeights.SemiBold,
+            Foreground = TryFindResource("Accent") as Brush ?? Brushes.RoyalBlue,
+            HorizontalAlignment = HorizontalAlignment.Center
+        });
+        panel.Children.Add(new TextBlock
+        {
+            Text = isBusy ? "Preparing production workspace" : "Production FAT workspace",
+            FontSize = 18,
+            FontWeight = FontWeights.SemiBold,
+            Foreground = TryFindResource("Ink") as Brush ?? Brushes.Black,
+            Margin = new Thickness(0, 5, 0, 0),
+            HorizontalAlignment = HorizontalAlignment.Center
         });
+        panel.Children.Add(new TextBlock
+        {
+            Text = string.IsNullOrWhiteSpace(statusText)
+                ? "Select an Engineering IED with static DataSet scope, then open FAT."
+                : statusText,
+            FontSize = 11.5,
+            Foreground = TryFindResource("Muted") as Brush ?? Brushes.DimGray,
+            TextAlignment = TextAlignment.Center,
+            TextWrapping = TextWrapping.Wrap,
+            Margin = new Thickness(0, 8, 0, 0)
+        });
+
+        if (isBusy)
+        {
+            panel.Children.Add(new ProgressBar
+            {
+                Height = 4,
+                IsIndeterminate = true,
+                BorderThickness = new Thickness(0),
+                Margin = new Thickness(0, 18, 0, 0),
+                Foreground = TryFindResource("Accent") as Brush ?? Brushes.RoyalBlue,
+                Background = new SolidColorBrush(Color.FromRgb(220, 231, 248))
+            });
+        }
+
+        card.Child = panel;
+        root.Children.Add(card);
         return root;
     }
 
+    internal void ShowProductionFatBootstrapState(string message, bool isBusy)
+    {
+        if (!ProductionFatTabReady || _productionFatWindow is { IsLoaded: true })
+            return;
+
+        NativeFatTab.Content = BuildProductionFatPermanentHost(message, isBusy);
+    }
+
     private void ProductionFat_MainTabsSelectionChanged(object sender, SelectionChangedEventArgs e)
     {
         if (!ReferenceEquals(e.Source, MainTabs))

From b305c0c7639b7b288e13015f6d8c21e962be1c24 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Fri, 11 Sep 2026 14:50:11 +0700
Subject: [PATCH 74/84] fix(fat): expose deterministic bootstrap state in
 permanent shell

---
 ...Window.ProductionFatEngineeringBootstrap.cs | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/MainWindow.ProductionFatEngineeringBootstrap.cs b/MainWindow.ProductionFatEngineeringBootstrap.cs
index 67f14f93e..fdebadc9f 100644
--- a/MainWindow.ProductionFatEngineeringBootstrap.cs
+++ b/MainWindow.ProductionFatEngineeringBootstrap.cs
@@ -91,6 +91,10 @@ private async Task EnsureProductionFatFromEngineeringAsync()
         if (selected?.SclWorkspace == null ||
             selected.SclWorkspace.DesignModel.DataSets.Sum(dataSet => dataSet.Members.Count) == 0)
         {
+            var message = selected == null
+                ? "Select an Engineering IED with a static DataSet to prepare FAT."
+                : $"{selected.Name} has no static DataSet scope in the Engineering SCL model.";
+            ShowProductionFatBootstrapState(message, isBusy: false);
             SetStatus(selected == null
                 ? "FAT · select an Engineering IED with a static DataSet."
                 : $"FAT · {selected.Name} has no static DataSet scope in the Engineering SCL model.");
@@ -104,6 +108,8 @@ private async Task EnsureProductionFatFromEngineeringAsync()
             .ToArray();
         if (engineeringDevices.All(device => !ReferenceEquals(device, selected)))
         {
+            var message = $"Engineering source provenance for {selected.Name} is unavailable. Reopen the SCL source to restore FAT authority.";
+            ShowProductionFatBootstrapState(message, isBusy: false);
             SetStatus($"FAT · Engineering source provenance for {selected.Name} is unavailable; use Open SCL to restore the source authority.");
             return;
         }
@@ -113,6 +119,9 @@ private async Task EnsureProductionFatFromEngineeringAsync()
         _productionFatEngineeringBootstrapCts?.Dispose();
         _productionFatEngineeringBootstrapCts = CancellationTokenSource.CreateLinkedTokenSource(_applicationCancellation.Token);
         var token = _productionFatEngineeringBootstrapCts.Token;
+        ShowProductionFatBootstrapState(
+            $"Reusing {selected.Name} from the Engineering static DataSet authority. No reconnect or SCL re-import is started.",
+            isBusy: true);
         SetStatus($"FAT · preparing {selected.Name} from the Engineering static DataSet…");
 
         try
@@ -172,10 +181,19 @@ private async Task EnsureProductionFatFromEngineeringAsync()
         catch (OperationCanceledException)
         {
             // Fast navigation/close is normal. No modal interruption is appropriate here.
+            if (MainTabs.SelectedIndex == NativeFatWorkspaceIndex && _productionFatWindow == null)
+            {
+                ShowProductionFatBootstrapState(
+                    "FAT preparation was cancelled. Select the FAT tab again to retry from the current Engineering authority.",
+                    isBusy: false);
+            }
         }
         catch (Exception ex) when (ex is IOException or JsonException or InvalidDataException or UnauthorizedAccessException or ArgumentException or InvalidOperationException)
         {
             AddLog("WARN", "FAT", $"Automatic Engineering FAT bootstrap unavailable: {ex.Message}");
+            ShowProductionFatBootstrapState(
+                $"FAT could not reuse the current Engineering static DataSet: {ex.Message}",
+                isBusy: false);
             SetStatus($"FAT · could not reuse the Engineering static DataSet automatically: {ex.Message}");
         }
         finally

From 91290742d3bd4d6b1610125611d7f24a3dbf94db Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Fri, 11 Sep 2026 14:53:00 +0700
Subject: [PATCH 75/84] style(fat): compact production grid and widen IEC
 reference

---
 IoListTestingWindow.xaml | 178 +++++++++++++++++++--------------------
 1 file changed, 89 insertions(+), 89 deletions(-)

diff --git a/IoListTestingWindow.xaml b/IoListTestingWindow.xaml
index 48b1a7bb5..1b0803998 100644
--- a/IoListTestingWindow.xaml
+++ b/IoListTestingWindow.xaml
@@ -7,7 +7,7 @@
         Height="900" Width="1500" MinHeight="760" MinWidth="1180"
         WindowStartupLocation="CenterOwner" WindowState="Maximized"
         Background="{StaticResource AppBackgroundGradient}"
-        FontFamily="Aptos, Segoe UI Variable Text, Segoe UI, Calibri"
+        FontFamily="Inter, Segoe UI Variable Text, Segoe UI, Calibri"
         Icon="Assets/app-icon.ico"
         Closing="Window_Closing"
         ContentRendered="IoListTestingWindow_ContentRendered">
@@ -17,11 +17,11 @@
         <Style x:Key="FatGridText" TargetType="TextBlock">
             <Setter Property="VerticalAlignment" Value="Center"/>
             <Setter Property="Foreground" Value="{StaticResource Ink}"/>
-            <Setter Property="FontSize" Value="12.2"/>
+            <Setter Property="FontSize" Value="11.5"/>
             <Setter Property="TextTrimming" Value="CharacterEllipsis"/>
         </Style>
         <Style TargetType="DataGridCell">
-            <Setter Property="Padding" Value="8,6"/>
+            <Setter Property="Padding" Value="7,4"/>
             <Setter Property="BorderThickness" Value="0,0,0,1"/>
             <Setter Property="BorderBrush" Value="#E8EDF5"/>
             <Setter Property="Background" Value="Transparent"/>
@@ -29,11 +29,11 @@
             <Setter Property="FocusVisualStyle" Value="{x:Null}"/>
         </Style>
         <Style TargetType="DataGridColumnHeader">
-            <Setter Property="Height" Value="38"/>
-            <Setter Property="Padding" Value="8,0"/>
+            <Setter Property="Height" Value="34"/>
+            <Setter Property="Padding" Value="7,0"/>
             <Setter Property="Background" Value="#F4F7FB"/>
             <Setter Property="Foreground" Value="#617087"/>
-            <Setter Property="FontSize" Value="10.5"/>
+            <Setter Property="FontSize" Value="10.2"/>
             <Setter Property="FontWeight" Value="SemiBold"/>
             <Setter Property="BorderThickness" Value="0,0,0,1"/>
             <Setter Property="BorderBrush" Value="#DCE4EF"/>
@@ -45,7 +45,7 @@
             <Setter Property="HorizontalContentAlignment" Value="Center"/>
         </Style>
         <Style TargetType="DataGridRow">
-            <Setter Property="MinHeight" Value="48"/>
+            <Setter Property="MinHeight" Value="40"/>
             <Setter Property="Background" Value="#FFFFFF"/>
             <Setter Property="BorderThickness" Value="0"/>
             <Style.Triggers>
@@ -59,16 +59,16 @@
         </Style>
     </Window.Resources>
 
-    <Grid Margin="14">
+    <Grid Margin="12">
         <Grid.RowDefinitions>
             <RowDefinition Height="Auto"/>
-            <RowDefinition Height="12"/>
-            <RowDefinition Height="*"/>
             <RowDefinition Height="10"/>
+            <RowDefinition Height="*"/>
+            <RowDefinition Height="8"/>
             <RowDefinition Height="Auto"/>
         </Grid.RowDefinitions>
 
-        <Border Grid.Row="0" Style="{StaticResource Card}" Padding="16,12">
+        <Border Grid.Row="0" Style="{StaticResource Card}" Padding="14,10">
             <Grid>
                 <Grid.ColumnDefinitions>
                     <ColumnDefinition Width="*"/>
@@ -76,24 +76,24 @@
                 </Grid.ColumnDefinitions>
                 <StackPanel VerticalAlignment="Center">
                     <TextBlock Text="IO LIST FAT" Style="{StaticResource MicroLabel}" Foreground="{StaticResource Accent}"/>
-                    <TextBlock Text="{Binding Project.ProjectName}" FontSize="18" FontWeight="SemiBold"
+                    <TextBlock Text="{Binding Project.ProjectName}" FontSize="17" FontWeight="SemiBold"
                                Foreground="{StaticResource Ink}" Margin="0,2,0,0"/>
-                    <TextBlock Text="Workbook scope · report-first acquisition · relay-timestamped evidence"
+                    <TextBlock Text="Engineering SCL scope · report-first acquisition · relay-timestamped evidence"
                                Style="{StaticResource Caption}" Margin="0,3,0,0"/>
                 </StackPanel>
                 <WrapPanel Grid.Column="1" VerticalAlignment="Center" HorizontalAlignment="Right">
-                    <Border Background="#F1F5FB" CornerRadius="14" Padding="12,7" Margin="0,0,9,0">
-                        <TextBlock Text="{Binding ProjectSummary}" FontSize="11.8" Foreground="{StaticResource Ink}"/>
+                    <Border Background="#F1F5FB" CornerRadius="14" Padding="11,6" Margin="0,0,8,0">
+                        <TextBlock Text="{Binding ProjectSummary}" FontSize="11.4" Foreground="{StaticResource Ink}"/>
                     </Border>
-                    <Button Content="Save" Style="{StaticResource SoftButton}" Padding="11,7"
-                            Click="SaveProgress_Click" Margin="0,0,6,0"/>
-                    <Button Content="Excel" Style="{StaticResource SoftButton}" Padding="11,7"
-                            Click="ExportExcel_Click" Margin="0,0,6,0"/>
-                    <Button Content="PDF" Style="{StaticResource SoftButton}" Padding="11,7"
-                            Click="ExportPdf_Click" Margin="0,0,6,0"/>
-                    <Button Content="Export .arsas" Style="{StaticResource PrimaryButton}" Padding="12,7"
-                            Click="ExportHandover_Click" Margin="0,0,6,0"/>
-                    <Button Content="Engineering" Style="{StaticResource SoftButton}" Padding="11,7"
+                    <Button Content="Save" Style="{StaticResource SoftButton}" Padding="10,6"
+                            Click="SaveProgress_Click" Margin="0,0,5,0"/>
+                    <Button Content="Excel" Style="{StaticResource SoftButton}" Padding="10,6"
+                            Click="ExportExcel_Click" Margin="0,0,5,0"/>
+                    <Button Content="PDF" Style="{StaticResource SoftButton}" Padding="10,6"
+                            Click="ExportPdf_Click" Margin="0,0,5,0"/>
+                    <Button Content="Export .arsas" Style="{StaticResource PrimaryButton}" Padding="11,6"
+                            Click="ExportHandover_Click" Margin="0,0,5,0"/>
+                    <Button Content="Engineering" Style="{StaticResource SoftButton}" Padding="10,6"
                             Click="ReturnToEngineering_Click"/>
                 </WrapPanel>
             </Grid>
@@ -101,21 +101,21 @@
 
         <Grid Grid.Row="2">
             <Grid.ColumnDefinitions>
-                <ColumnDefinition Width="304"/>
-                <ColumnDefinition Width="12"/>
+                <ColumnDefinition Width="282"/>
+                <ColumnDefinition Width="10"/>
                 <ColumnDefinition Width="*"/>
             </Grid.ColumnDefinitions>
 
-            <Border Grid.Column="0" Style="{StaticResource Card}" Padding="10">
+            <Border Grid.Column="0" Style="{StaticResource Card}" Padding="9">
                 <DockPanel>
-                    <Grid DockPanel.Dock="Top" Margin="5,3,5,11">
+                    <Grid DockPanel.Dock="Top" Margin="5,3,5,9">
                         <Grid.ColumnDefinitions>
                             <ColumnDefinition Width="*"/>
                             <ColumnDefinition Width="Auto"/>
                         </Grid.ColumnDefinitions>
                         <StackPanel>
                             <TextBlock Text="IED EXPLORER" Style="{StaticResource MicroLabel}"/>
-                            <TextBlock Text="Workbook devices" Style="{StaticResource Caption}" Margin="0,2,0,0"/>
+                            <TextBlock Text="Engineering FAT devices" Style="{StaticResource Caption}" Margin="0,2,0,0"/>
                         </StackPanel>
                         <Border Grid.Column="1" Background="#F1F5FB" CornerRadius="12" Padding="8,4" VerticalAlignment="Center">
                             <TextBlock Text="{Binding Project.Ieds.Count}" FontWeight="SemiBold" FontSize="11"
@@ -124,7 +124,7 @@
                     </Grid>
 
                     <Button DockPanel.Dock="Bottom" Content="＋ Add IED · Import SCL"
-                            Style="{StaticResource PrimaryButton}" Margin="4,10,4,2" Padding="12,9"
+                            Style="{StaticResource PrimaryButton}" Margin="4,8,4,2" Padding="11,8"
                             IsEnabled="{Binding CanAddFatIed}" Click="AddFatIedFromScl_Click"
                             ToolTip="Add another IED from CID/SCD/ICD/IID without replacing the current FAT workspace"/>
 
@@ -137,7 +137,7 @@
                         <ListBox.ItemContainerStyle>
                             <Style TargetType="ListBoxItem">
                                 <Setter Property="Padding" Value="0"/>
-                                <Setter Property="Margin" Value="0,0,0,8"/>
+                                <Setter Property="Margin" Value="0,0,0,7"/>
                                 <Setter Property="HorizontalContentAlignment" Value="Stretch"/>
                                 <Setter Property="Background" Value="Transparent"/>
                                 <Setter Property="BorderThickness" Value="0"/>
@@ -146,7 +146,7 @@
                                     <Setter.Value>
                                         <ControlTemplate TargetType="ListBoxItem">
                                             <Border x:Name="IedCard" Background="#FAFCFF" BorderBrush="#D8E1EE"
-                                                    BorderThickness="1" CornerRadius="15" Padding="10">
+                                                    BorderThickness="1" CornerRadius="14" Padding="9">
                                                 <ContentPresenter/>
                                             </Border>
                                             <ControlTemplate.Triggers>
@@ -166,14 +166,14 @@
                         </ListBox.ItemContainerStyle>
                         <ListBox.ItemTemplate>
                             <DataTemplate>
-                                <Grid MinHeight="70">
+                                <Grid MinHeight="64">
                                     <Grid.ColumnDefinitions>
-                                        <ColumnDefinition Width="58"/>
+                                        <ColumnDefinition Width="54"/>
                                         <ColumnDefinition Width="*"/>
                                     </Grid.ColumnDefinitions>
-                                    <StackPanel Grid.Column="0" Width="56"
+                                    <StackPanel Grid.Column="0" Width="52"
                                                 HorizontalAlignment="Center" VerticalAlignment="Center">
-                                        <Viewbox Width="46" Height="46" HorizontalAlignment="Center">
+                                        <Viewbox Width="42" Height="42" HorizontalAlignment="Center">
                                             <Control x:Name="RelayIcon" Width="50" Height="50" Foreground="#D94B55"
                                                      Template="{StaticResource IedRelayFrontPanelTemplate}"/>
                                         </Viewbox>
@@ -202,12 +202,12 @@
                                                 <ColumnDefinition Width="*"/>
                                                 <ColumnDefinition Width="Auto"/>
                                             </Grid.ColumnDefinitions>
-                                            <TextBlock Text="{Binding IedName}" FontSize="12.8" FontWeight="SemiBold"
+                                            <TextBlock Text="{Binding IedName}" FontSize="12.4" FontWeight="SemiBold"
                                                        Foreground="{StaticResource Ink}" TextTrimming="CharacterEllipsis"
-                                                       Margin="0,0,10,0" VerticalAlignment="Center"/>
+                                                       Margin="0,0,9,0" VerticalAlignment="Center"/>
                                             <Border Grid.Column="1" Background="#EAF8F1" BorderBrush="#8FD1B1"
                                                     BorderThickness="1" CornerRadius="9" Padding="7,2"
-                                                    Margin="10,0,0,0" VerticalAlignment="Center">
+                                                    Margin="9,0,0,0" VerticalAlignment="Center">
                                                 <Border.Visibility>
                                                     <MultiBinding Converter="{StaticResource AllPassedVisibilityConverter}">
                                                         <Binding Path="TestPoints.Count"/>
@@ -218,8 +218,8 @@
                                             </Border>
                                         </Grid>
                                         <TextBlock Grid.Row="1" Text="{Binding IpAddress}" Style="{StaticResource Caption}"
-                                                   Margin="0,3,0,0"/>
-                                        <TextBlock Grid.Row="2" Margin="0,7,0,0" FontSize="10.5"
+                                                   Margin="0,2,0,0"/>
+                                        <TextBlock Grid.Row="2" Margin="0,6,0,0" FontSize="10.2"
                                                    Foreground="{StaticResource Muted}">
                                             <Run Text="{Binding BoundCount, Mode=OneWay}"/>
                                             <Run Text=" live  ·  "/>
@@ -231,7 +231,7 @@
                                         <ProgressBar x:Name="CardProgress"
                                                      Grid.Row="3"
                                                      Height="3"
-                                                     Margin="0,8,0,0"
+                                                     Margin="0,7,0,0"
                                                      Minimum="0"
                                                      Maximum="100"
                                                      IsIndeterminate="True"
@@ -268,12 +268,12 @@
                 </DockPanel>
             </Border>
 
-            <Border Grid.Column="2" Style="{StaticResource Card}" Padding="12">
+            <Border Grid.Column="2" Style="{StaticResource Card}" Padding="10">
                 <Grid>
                     <Grid.RowDefinitions>
                         <RowDefinition Height="Auto"/>
                         <RowDefinition Height="Auto"/>
-                        <RowDefinition Height="12"/>
+                        <RowDefinition Height="10"/>
                         <RowDefinition Height="*"/>
                     </Grid.RowDefinitions>
 
@@ -282,47 +282,47 @@
                             <ColumnDefinition Width="*"/>
                             <ColumnDefinition Width="Auto"/>
                         </Grid.ColumnDefinitions>
-                        <StackPanel VerticalAlignment="Center" Margin="0,0,14,0">
-                            <TextBlock Text="{Binding SelectedIed.IedName}" FontSize="17" FontWeight="SemiBold"
+                        <StackPanel VerticalAlignment="Center" Margin="0,0,12,0">
+                            <TextBlock Text="{Binding SelectedIed.IedName}" FontSize="16" FontWeight="SemiBold"
                                        Foreground="{StaticResource Ink}"/>
-                            <TextBlock Text="{Binding SelectedIedSummary}" Style="{StaticResource Caption}" Margin="0,4,0,0"/>
+                            <TextBlock Text="{Binding SelectedIedSummary}" Style="{StaticResource Caption}" Margin="0,3,0,0"/>
                         </StackPanel>
                         <StackPanel Grid.Column="1" Orientation="Horizontal" VerticalAlignment="Center">
                             <Button x:Name="WorkspacePreviewToggle"
                                     Content="Print Preview"
                                     Style="{StaticResource SoftButton}"
-                                    Padding="11,8"
+                                    Padding="10,7"
                                     Click="TogglePrintPreview_Click"
-                                    Margin="0,0,10,0"/>
+                                    Margin="0,0,8,0"/>
                             <Button Content="{Binding SelectedStartWorkflowText}" Style="{StaticResource PrimaryButton}"
-                                    Padding="13,8" IsEnabled="{Binding SelectedCanStartWorkflow}"
-                                    Click="StartSelectedIedSafely_Click" Margin="0,0,6,0"/>
-                            <Button Content="Pause" Style="{StaticResource SoftButton}" Padding="11,8"
-                                    IsEnabled="{Binding SelectedCanPause}" Click="PauseSession_Click" Margin="0,0,6,0"/>
-                            <Button Content="Resume" Style="{StaticResource SoftButton}" Padding="11,8"
-                                    IsEnabled="{Binding SelectedCanResume}" Click="ResumeSession_Click" Margin="0,0,6,0"/>
-                            <Button Content="Stop" Style="{StaticResource SoftButton}" Padding="11,8"
+                                    Padding="12,7" IsEnabled="{Binding SelectedCanStartWorkflow}"
+                                    Click="StartSelectedIedSafely_Click" Margin="0,0,5,0"/>
+                            <Button Content="Pause" Style="{StaticResource SoftButton}" Padding="10,7"
+                                    IsEnabled="{Binding SelectedCanPause}" Click="PauseSession_Click" Margin="0,0,5,0"/>
+                            <Button Content="Resume" Style="{StaticResource SoftButton}" Padding="10,7"
+                                    IsEnabled="{Binding SelectedCanResume}" Click="ResumeSession_Click" Margin="0,0,5,0"/>
+                            <Button Content="Stop" Style="{StaticResource SoftButton}" Padding="10,7"
                                     IsEnabled="{Binding SelectedCanStop}" Click="StopSession_Click"/>
                         </StackPanel>
                     </Grid>
 
                     <Border Grid.Row="1" Visibility="{Binding PreparationVisibility}"
                             Background="#F3F7FF" BorderBrush="#B9CCF4" BorderThickness="1"
-                            CornerRadius="13" Padding="12,9" Margin="0,11,0,0">
+                            CornerRadius="12" Padding="11,8" Margin="0,9,0,0">
                         <StackPanel>
                             <Grid>
                                 <Grid.ColumnDefinitions>
                                     <ColumnDefinition Width="Auto"/>
                                     <ColumnDefinition Width="*"/>
                                 </Grid.ColumnDefinitions>
-                                <TextBlock Text="{Binding PreparationIedText}" FontSize="11.8" FontWeight="SemiBold"
+                                <TextBlock Text="{Binding PreparationIedText}" FontSize="11.5" FontWeight="SemiBold"
                                            Foreground="{StaticResource Ink}" VerticalAlignment="Center"/>
-                                <TextBlock Grid.Column="1" Text="{Binding PreparationStatusText}" FontSize="10.8"
-                                           Foreground="#526783" Margin="12,0,0,0" VerticalAlignment="Center"
+                                <TextBlock Grid.Column="1" Text="{Binding PreparationStatusText}" FontSize="10.6"
+                                           Foreground="#526783" Margin="11,0,0,0" VerticalAlignment="Center"
                                            TextTrimming="CharacterEllipsis"/>
                             </Grid>
                             <ProgressBar Height="4"
-                                         Margin="0,9,0,0"
+                                         Margin="0,8,0,0"
                                          IsIndeterminate="True"
                                          BorderThickness="0"
                                          Background="#DCE7F8"
@@ -349,16 +349,16 @@
                               SelectionMode="Single"
                               SelectionUnit="FullRow"
                               RowHeaderWidth="0"
-                               FrozenColumnCount="1"
-                               EnableRowVirtualization="True"
-                               EnableColumnVirtualization="True"
-                               VirtualizingPanel.IsVirtualizing="True"
-                               VirtualizingPanel.VirtualizationMode="Recycling"
-                               ScrollViewer.CanContentScroll="True"
-                               ScrollViewer.HorizontalScrollBarVisibility="Auto"
+                              FrozenColumnCount="1"
+                              EnableRowVirtualization="True"
+                              EnableColumnVirtualization="True"
+                              VirtualizingPanel.IsVirtualizing="True"
+                              VirtualizingPanel.VirtualizationMode="Recycling"
+                              ScrollViewer.CanContentScroll="True"
+                              ScrollViewer.HorizontalScrollBarVisibility="Auto"
                               ScrollViewer.VerticalScrollBarVisibility="Auto">
                         <DataGrid.Columns>
-                            <DataGridTemplateColumn Header="TEST" Width="48" HeaderStyle="{StaticResource CenteredFatGridHeader}">
+                            <DataGridTemplateColumn Header="TEST" Width="46" HeaderStyle="{StaticResource CenteredFatGridHeader}">
                                 <DataGridTemplateColumn.CellTemplate>
                                     <DataTemplate>
                                         <CheckBox IsChecked="{Binding TestEnabled, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
@@ -367,7 +367,7 @@
                                     </DataTemplate>
                                 </DataGridTemplateColumn.CellTemplate>
                             </DataGridTemplateColumn>
-                            <DataGridTemplateColumn Header="SIGNAL" Width="1.55*" MinWidth="190" MaxWidth="300">
+                            <DataGridTemplateColumn Header="SIGNAL" Width="1.35*" MinWidth="170" MaxWidth="260">
                                 <DataGridTemplateColumn.CellTemplate>
                                     <DataTemplate>
                                         <TextBlock Text="{Binding SignalName}" Style="{StaticResource FatGridText}"
@@ -375,20 +375,20 @@
                                     </DataTemplate>
                                 </DataGridTemplateColumn.CellTemplate>
                             </DataGridTemplateColumn>
-                            <DataGridTemplateColumn Header="IEC REFERENCE" Width="1.85*" MinWidth="235" MaxWidth="360">
+                            <DataGridTemplateColumn Header="IEC REFERENCE" Width="2.25*" MinWidth="290" MaxWidth="480">
                                 <DataGridTemplateColumn.CellTemplate>
                                     <DataTemplate>
                                         <TextBlock Text="{Binding ObjectReference}" Style="{StaticResource FatGridText}"
-                                                   FontFamily="Cascadia Mono, Consolas" FontSize="11.0"
+                                                   FontFamily="Cascadia Mono, Consolas" FontSize="10.8"
                                                    Foreground="#52627A" ToolTip="{Binding ObjectReference}"/>
                                     </DataTemplate>
                                 </DataGridTemplateColumn.CellTemplate>
                             </DataGridTemplateColumn>
-                            <DataGridTemplateColumn Header="LIVE" Width="82" HeaderStyle="{StaticResource CenteredFatGridHeader}">
+                            <DataGridTemplateColumn Header="LIVE" Width="76" HeaderStyle="{StaticResource CenteredFatGridHeader}">
                                 <DataGridTemplateColumn.CellTemplate>
                                     <DataTemplate>
                                         <TextBlock x:Name="LiveText" Text="{Binding LiveBindingText}"
-                                                   Style="{StaticResource FatGridText}" FontSize="10.8"
+                                                   Style="{StaticResource FatGridText}" FontSize="10.5"
                                                    FontWeight="SemiBold" Foreground="#65758B"
                                                    ToolTip="{Binding LiveBindingReason}"/>
                                         <DataTemplate.Triggers>
@@ -399,7 +399,7 @@
                                     </DataTemplate>
                                 </DataGridTemplateColumn.CellTemplate>
                             </DataGridTemplateColumn>
-                            <DataGridTemplateColumn Header="VALUE" Width="78" HeaderStyle="{StaticResource CenteredFatGridHeader}">
+                            <DataGridTemplateColumn Header="VALUE" Width="72" HeaderStyle="{StaticResource CenteredFatGridHeader}">
                                 <DataGridTemplateColumn.CellTemplate>
                                     <DataTemplate>
                                         <TextBlock Text="{Binding Runtime.CurrentValue}" Style="{StaticResource FatGridText}"
@@ -407,60 +407,60 @@
                                     </DataTemplate>
                                 </DataGridTemplateColumn.CellTemplate>
                             </DataGridTemplateColumn>
-                            <DataGridTemplateColumn Header="QUALITY" Width="88" HeaderStyle="{StaticResource CenteredFatGridHeader}">
+                            <DataGridTemplateColumn Header="QUALITY" Width="82" HeaderStyle="{StaticResource CenteredFatGridHeader}">
                                 <DataGridTemplateColumn.CellTemplate>
                                     <DataTemplate>
                                         <TextBlock Text="{Binding Runtime.CurrentQuality}" Style="{StaticResource FatGridText}"
-                                                   FontSize="11.2" ToolTip="{Binding Runtime.CurrentQuality}"/>
+                                                   FontSize="10.8" ToolTip="{Binding Runtime.CurrentQuality}"/>
                                     </DataTemplate>
                                 </DataGridTemplateColumn.CellTemplate>
                             </DataGridTemplateColumn>
-                            <DataGridTemplateColumn Header="ACQUISITION" Width="136" HeaderStyle="{StaticResource CenteredFatGridHeader}">
+                            <DataGridTemplateColumn Header="ACQUISITION" Width="122" HeaderStyle="{StaticResource CenteredFatGridHeader}">
                                 <DataGridTemplateColumn.CellTemplate>
                                     <DataTemplate>
                                         <TextBlock Text="{Binding Runtime.CurrentSource}" Style="{StaticResource FatGridText}"
-                                                   FontSize="10.8" FontWeight="SemiBold" Foreground="#405B7D"
+                                                   FontSize="10.4" FontWeight="SemiBold" Foreground="#405B7D"
                                                    ToolTip="{Binding Runtime.CurrentSource}"/>
                                     </DataTemplate>
                                 </DataGridTemplateColumn.CellTemplate>
                             </DataGridTemplateColumn>
-                            <DataGridTemplateColumn Header="ON · RELAY TIME" Width="168"
+                            <DataGridTemplateColumn Header="ON · RELAY TIME" Width="154"
                                                     HeaderStyle="{StaticResource CenteredFatGridHeader}">
                                 <DataGridTemplateColumn.CellTemplate>
                                     <DataTemplate>
                                         <TextBlock Text="{Binding Runtime.OnRelayTimestampText}"
                                                    Style="{StaticResource FatGridText}"
-                                                   FontFamily="Cascadia Mono, Consolas" FontSize="10.4"
+                                                   FontFamily="Cascadia Mono, Consolas" FontSize="10.1"
                                                    ToolTip="{Binding Runtime.OnEvidenceToolTip}"/>
                                     </DataTemplate>
                                 </DataGridTemplateColumn.CellTemplate>
                             </DataGridTemplateColumn>
-                            <DataGridTemplateColumn Header="OFF · RELAY TIME" Width="168"
+                            <DataGridTemplateColumn Header="OFF · RELAY TIME" Width="154"
                                                     HeaderStyle="{StaticResource CenteredFatGridHeader}">
                                 <DataGridTemplateColumn.CellTemplate>
                                     <DataTemplate>
                                         <TextBlock Text="{Binding Runtime.OffRelayTimestampText}"
                                                    Style="{StaticResource FatGridText}"
-                                                   FontFamily="Cascadia Mono, Consolas" FontSize="10.4"
+                                                   FontFamily="Cascadia Mono, Consolas" FontSize="10.1"
                                                    ToolTip="{Binding Runtime.OffEvidenceToolTip}"/>
                                     </DataTemplate>
                                 </DataGridTemplateColumn.CellTemplate>
                             </DataGridTemplateColumn>
-                            <DataGridTemplateColumn Header="STATUS" Width="118" HeaderStyle="{StaticResource CenteredFatGridHeader}">
+                            <DataGridTemplateColumn Header="STATUS" Width="108" HeaderStyle="{StaticResource CenteredFatGridHeader}">
                                 <DataGridTemplateColumn.CellTemplate>
                                     <DataTemplate>
                                         <TextBlock Text="{Binding Runtime.StateText}" Style="{StaticResource FatGridText}"
-                                                   FontSize="10.7" FontWeight="SemiBold" Foreground="#607089"
+                                                   FontSize="10.4" FontWeight="SemiBold" Foreground="#607089"
                                                    ToolTip="{Binding Runtime.StatusReason}"/>
                                     </DataTemplate>
                                 </DataGridTemplateColumn.CellTemplate>
                             </DataGridTemplateColumn>
-                            <DataGridTemplateColumn Header="RESULT" Width="92" HeaderStyle="{StaticResource CenteredFatGridHeader}">
+                            <DataGridTemplateColumn Header="RESULT" Width="86" HeaderStyle="{StaticResource CenteredFatGridHeader}">
                                 <DataGridTemplateColumn.CellTemplate>
                                     <DataTemplate>
                                         <TextBlock x:Name="FinalResultText" Text="—"
                                                    Style="{StaticResource FatGridText}"
-                                                   FontSize="10.8" FontWeight="Bold"
+                                                   FontSize="10.5" FontWeight="Bold"
                                                    Foreground="#8A97A9"
                                                    ToolTip="{Binding Runtime.StatusReason}"/>
                                         <DataTemplate.Triggers>
@@ -490,7 +490,7 @@
         </Grid>
 
         <Border Grid.Row="4" Background="#F8FAFD" BorderBrush="#DEE6F0"
-                BorderThickness="1" CornerRadius="13" Padding="12,8">
+                BorderThickness="1" CornerRadius="12" Padding="11,7">
             <Grid>
                 <Grid.ColumnDefinitions>
                     <ColumnDefinition Width="1.4*"/>
@@ -515,4 +515,4 @@
             </Grid>
         </Border>
     </Grid>
-</Window>
+</Window>
\ No newline at end of file

From d40feb63b5d3212387cb262ab7e99fcb83671dee Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Fri, 11 Sep 2026 14:56:20 +0700
Subject: [PATCH 76/84] test(fat): lock compact grid density and wider IEC
 reference

---
 tests/ARSAS.Tests/IoTestingUiContractTests.cs | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/tests/ARSAS.Tests/IoTestingUiContractTests.cs b/tests/ARSAS.Tests/IoTestingUiContractTests.cs
index 1e430db40..4ab3cd33b 100644
--- a/tests/ARSAS.Tests/IoTestingUiContractTests.cs
+++ b/tests/ARSAS.Tests/IoTestingUiContractTests.cs
@@ -195,7 +195,8 @@ public void IoTestingWindow_UsesRelayTimestampEvidenceAndPremiumGridDensity()
         Assert.Contains(
             document.Descendants(presentation + "Setter"),
             setter => (string?)setter.Attribute("Property") == "MinHeight" &&
-                      (string?)setter.Attribute("Value") == "48");
+                      (string?)setter.Attribute("Value") == "40");
+        Assert.StartsWith("Inter", (string?)document.Root?.Attribute("FontFamily"), StringComparison.Ordinal);
         Assert.Contains("RelayIcon", text, StringComparison.Ordinal);
         Assert.Contains("CardStateText", text, StringComparison.Ordinal);
         Assert.Contains("✔ PASS", text, StringComparison.Ordinal);
@@ -270,11 +271,13 @@ public void IoTestingWindow_UsesBalancedInitialGridWidthsAndCenteredRelayHeaders
         var onTime = FindColumn(document, presentation, "ON · RELAY TIME");
         var offTime = FindColumn(document, presentation, "OFF · RELAY TIME");
 
-        Assert.Equal("1.55*", (string?)signal.Attribute("Width"));
-        Assert.Equal("1.85*", (string?)reference.Attribute("Width"));
-        Assert.Equal("136", (string?)acquisition.Attribute("Width"));
-        Assert.Equal("168", (string?)onTime.Attribute("Width"));
-        Assert.Equal("168", (string?)offTime.Attribute("Width"));
+        Assert.Equal("1.35*", (string?)signal.Attribute("Width"));
+        Assert.Equal("2.25*", (string?)reference.Attribute("Width"));
+        Assert.Equal("290", (string?)reference.Attribute("MinWidth"));
+        Assert.Equal("480", (string?)reference.Attribute("MaxWidth"));
+        Assert.Equal("122", (string?)acquisition.Attribute("Width"));
+        Assert.Equal("154", (string?)onTime.Attribute("Width"));
+        Assert.Equal("154", (string?)offTime.Attribute("Width"));
         Assert.Equal("{StaticResource CenteredFatGridHeader}", (string?)onTime.Attribute("HeaderStyle"));
         Assert.Equal("{StaticResource CenteredFatGridHeader}", (string?)offTime.Attribute("HeaderStyle"));
     }

From 20f8880a7baf314bb50bab3a6259d32fb991a250 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Fri, 11 Sep 2026 14:59:03 +0700
Subject: [PATCH 77/84] perf(fat): reuse verified source descriptions in
 persistence

---
 .../IoTestProjectPersistenceService.cs        | 34 +++++++++++++++++--
 1 file changed, 32 insertions(+), 2 deletions(-)

diff --git a/Services/IoTesting/IoTestProjectPersistenceService.cs b/Services/IoTesting/IoTestProjectPersistenceService.cs
index 7599f14e0..008e34a90 100644
--- a/Services/IoTesting/IoTestProjectPersistenceService.cs
+++ b/Services/IoTesting/IoTestProjectPersistenceService.cs
@@ -99,6 +99,38 @@ public static async Task<IoTestWorkspaceOpenResult> OpenSourcesAsync(
         cancellationToken.ThrowIfCancellationRequested();
 
         var described = await IoFatSourceWorkspaceService.DescribeAsync(sourceInputs, cancellationToken).ConfigureAwait(false);
+        return await OpenDescribedSourcesAsync(
+            importedProject,
+            session,
+            described,
+            localProjectsRoot,
+            evidenceRoot,
+            cancellationToken).ConfigureAwait(false);
+    }
+
+    /// <summary>
+    /// Opens a FAT workspace from a source set whose SHA-256 provenance has already been
+    /// calculated by an upstream authority in the same launch flow. This avoids hashing the
+    /// same SCL bytes again between Engineering projection and persistence. Staging still
+    /// reads every source and verifies its bytes against the supplied SHA-256 before the
+    /// canonical local copy is accepted, so this optimization never weakens content identity.
+    /// </summary>
+    public static async Task<IoTestWorkspaceOpenResult> OpenDescribedSourcesAsync(
+        IoTestProject importedProject,
+        IoTestSessionController session,
+        IReadOnlyCollection<IoFatDescribedSource> describedSources,
+        string localProjectsRoot,
+        string evidenceRoot,
+        CancellationToken cancellationToken = default)
+    {
+        ArgumentNullException.ThrowIfNull(importedProject);
+        ArgumentNullException.ThrowIfNull(session);
+        ArgumentNullException.ThrowIfNull(describedSources);
+        if (describedSources.Count == 0)
+            throw new InvalidDataException("A FAT workspace must contain at least one source file.");
+        cancellationToken.ThrowIfCancellationRequested();
+
+        var described = describedSources.ToArray();
         IoFatSourceIdentity.AttachOrValidate(importedProject, described.Select(source => source.Source).ToArray());
 
         var localDirectory = ProjectDirectory(localProjectsRoot, importedProject);
@@ -572,8 +604,6 @@ private void SaveFromTimer()
                     ReviewerComment = point.ReviewerComment
                 }).ToList())
             {
-                // M5: persist the stable Engineering DeviceId when available. Older snapshots
-                // omit this field and continue through the exact IEC identity + endpoint fallback.
                 LiveDeviceId = ied.LiveDeviceId,
                 LatestComtradeFiles = ied.LatestComtradeFiles,
                 LatestComtradeRemotePath = ied.LatestComtradeRemotePath,

From b78dea83634eade2f2bde2cf0f13f512a59cbbb5 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Fri, 11 Sep 2026 15:00:12 +0700
Subject: [PATCH 78/84] perf(fat): carry verified source descriptions through
 bootstrap

---
 .../IoTestWorkspaceBootstrapService.cs        | 36 +++++++++++++++++--
 1 file changed, 33 insertions(+), 3 deletions(-)

diff --git a/Services/IoTesting/IoTestWorkspaceBootstrapService.cs b/Services/IoTesting/IoTestWorkspaceBootstrapService.cs
index 25f7d3b55..d444880ab 100644
--- a/Services/IoTesting/IoTestWorkspaceBootstrapService.cs
+++ b/Services/IoTesting/IoTestWorkspaceBootstrapService.cs
@@ -45,6 +45,36 @@ public static async Task<IoTestWorkspaceLaunchResult> OpenSourcesAsync(
         ArgumentNullException.ThrowIfNull(sessionFactory);
 
         var described = await IoFatSourceWorkspaceService.DescribeAsync(sourceInputs, cancellationToken).ConfigureAwait(false);
+        return await OpenDescribedSourcesAsync(
+            importedProject,
+            described,
+            localProjectsRoot,
+            evidenceRoot,
+            sessionFactory,
+            cancellationToken).ConfigureAwait(false);
+    }
+
+    /// <summary>
+    /// Continues FAT bootstrap with source identities already SHA-256-described upstream.
+    /// The persistence layer accepts the same immutable descriptions and still verifies the
+    /// bytes again while staging them, so this removes redundant full-file hashing without
+    /// weakening the source/evidence boundary.
+    /// </summary>
+    public static async Task<IoTestWorkspaceLaunchResult> OpenDescribedSourcesAsync(
+        IoTestProject importedProject,
+        IReadOnlyCollection<IoFatDescribedSource> describedSources,
+        string localProjectsRoot,
+        string evidenceRoot,
+        Func<IoTestProject, string, IoTestSessionController> sessionFactory,
+        CancellationToken cancellationToken = default)
+    {
+        ArgumentNullException.ThrowIfNull(importedProject);
+        ArgumentNullException.ThrowIfNull(describedSources);
+        ArgumentNullException.ThrowIfNull(sessionFactory);
+        if (describedSources.Count == 0)
+            throw new InvalidDataException("A FAT workspace must contain at least one source file.");
+
+        var described = describedSources.ToArray();
         IoFatSourceIdentity.AttachOrValidate(importedProject, described.Select(source => source.Source).ToArray());
 
         var localDirectory = ProjectDirectory(localProjectsRoot, importedProject);
@@ -63,7 +93,7 @@ public static async Task<IoTestWorkspaceLaunchResult> OpenSourcesAsync(
             {
                 // Isolate the canonical persisted snapshot BEFORE attempting selective restore.
                 // Otherwise a rejected/invalid partial restore could fall through to
-                // IoTestWorkspacePersistence.OpenSourcesAsync(), which is allowed to restore a
+                // IoTestWorkspacePersistence.OpenDescribedSourcesAsync(), which is allowed to restore a
                 // matching snapshot wholesale. Engineering is the fresh plan authority here:
                 // the old snapshot is read-only evidence input, never a replacement project.
                 if (restoreSnapshotPath.Equals(snapshotPath, StringComparison.OrdinalIgnoreCase))
@@ -88,10 +118,10 @@ public static async Task<IoTestWorkspaceLaunchResult> OpenSourcesAsync(
             var session = sessionFactory(importedProject, evidenceRoot);
             try
             {
-                var opened = await IoTestWorkspacePersistence.OpenSourcesAsync(
+                var opened = await IoTestWorkspacePersistence.OpenDescribedSourcesAsync(
                     importedProject,
                     session,
-                    sourceInputs,
+                    described,
                     localProjectsRoot,
                     evidenceRoot,
                     cancellationToken).ConfigureAwait(false);

From a08e3e7c5c9c192b024688e3659dba5ec8d00bd0 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Fri, 11 Sep 2026 15:00:50 +0700
Subject: [PATCH 79/84] perf(fat): expose canonical described SCL sources from
 projection

---
 .../IoFatEngineeringWorkspaceProjectionService.cs        | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/Services/IoTesting/IoFatEngineeringWorkspaceProjectionService.cs b/Services/IoTesting/IoFatEngineeringWorkspaceProjectionService.cs
index 7c5efe44d..81eb06dd3 100644
--- a/Services/IoTesting/IoFatEngineeringWorkspaceProjectionService.cs
+++ b/Services/IoTesting/IoFatEngineeringWorkspaceProjectionService.cs
@@ -7,6 +7,7 @@ namespace ArIED61850Tester.Services.IoTesting;
 public sealed record IoFatEngineeringWorkspaceProjection(
     IoTestProject Project,
     IReadOnlyList<IoFatSourceInput> SourceInputs,
+    IReadOnlyList<IoFatDescribedSource> DescribedSources,
     IReadOnlyList<SclIedWorkspace> RuntimeWorkspaces);
 
 /// <summary>
@@ -72,6 +73,13 @@ public static async Task<IoFatEngineeringWorkspaceProjection> BuildAsync(
             .Distinct(StringComparer.OrdinalIgnoreCase)
             .Select(path => new IoFatSourceInput(path, IoFatSourceKinds.Scl))
             .ToArray();
+        var canonicalDescribedSources = sourceInputs
+            .Select(input =>
+            {
+                var path = Path.GetFullPath(input.FilePath);
+                return new IoFatDescribedSource(descriptorByPath[path], path);
+            })
+            .ToArray();
 
         var workspaceSources = canonicalDevices
             .Select(device =>
@@ -167,6 +175,7 @@ public static async Task<IoFatEngineeringWorkspaceProjection> BuildAsync(
         return new IoFatEngineeringWorkspaceProjection(
             project,
             sourceInputs,
+            canonicalDescribedSources,
             canonicalDevices.Select(device => device.SclWorkspace!).ToArray());
     }
 

From f76826ddbd9e0e0ed2a2621720457faff72681da Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Fri, 11 Sep 2026 15:01:26 +0700
Subject: [PATCH 80/84] perf(fat): remove repeated SCL hashing from Engineering
 bootstrap

---
 MainWindow.ProductionFatEngineeringBootstrap.cs | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/MainWindow.ProductionFatEngineeringBootstrap.cs b/MainWindow.ProductionFatEngineeringBootstrap.cs
index fdebadc9f..28ef4686d 100644
--- a/MainWindow.ProductionFatEngineeringBootstrap.cs
+++ b/MainWindow.ProductionFatEngineeringBootstrap.cs
@@ -136,9 +136,12 @@ private async Task EnsureProductionFatFromEngineeringAsync()
             // reparsing XML or starting a second model/acquisition stack.
             _ioFatSclProjectImportService.AdoptEngineeringRuntimeWorkspaces(projection.RuntimeWorkspaces);
 
-            var launch = await IoTestWorkspaceBootstrapService.OpenSourcesAsync(
+            // Projection already SHA-256-described the canonical Engineering SCL source set.
+            // Carry those exact identities through bootstrap/persistence instead of hashing
+            // the same files again. Staging still verifies every copied byte against SHA-256.
+            var launch = await IoTestWorkspaceBootstrapService.OpenDescribedSourcesAsync(
                 projection.Project,
-                projection.SourceInputs,
+                projection.DescribedSources,
                 IoTestingProjectsRoot(),
                 IoTestingEvidenceRoot(),
                 CreateIoTestSession,

From 2f9918bbbe2676de1dfe7910c685fd718424e254 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Fri, 11 Sep 2026 15:02:48 +0700
Subject: [PATCH 81/84] test(fat): guard single-hash Engineering source
 pipeline

---
 .../ProductionFatP0FieldRegressionTests.cs    | 22 +++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/tests/ARSAS.Tests/ProductionFatP0FieldRegressionTests.cs b/tests/ARSAS.Tests/ProductionFatP0FieldRegressionTests.cs
index 6b6beeff0..4368dc587 100644
--- a/tests/ARSAS.Tests/ProductionFatP0FieldRegressionTests.cs
+++ b/tests/ARSAS.Tests/ProductionFatP0FieldRegressionTests.cs
@@ -69,6 +69,28 @@ public void EngineeringBootstrap_AppliesStaticCleanupBeforeProductionWindowIsSho
         Assert.True(show > retire, "Static DataSet cleanup must complete before the production FAT workspace/session can be exposed.");
     }
 
+    [Fact]
+    public void EngineeringBootstrap_ReusesDescribedSourcesWhileStagingStillVerifiesSha256()
+    {
+        var projection = Read("Services/IoTesting/IoFatEngineeringWorkspaceProjectionService.cs");
+        var bootstrap = Read("MainWindow.ProductionFatEngineeringBootstrap.cs");
+        var bootstrapService = Read("Services/IoTesting/IoTestWorkspaceBootstrapService.cs");
+        var persistence = Read("Services/IoTesting/IoTestProjectPersistenceService.cs");
+        var sourceWorkspace = Read("Services/IoTesting/IoFatSourceWorkspaceService.cs");
+
+        Assert.Contains("IReadOnlyList<IoFatDescribedSource> DescribedSources", projection, StringComparison.Ordinal);
+        Assert.Equal(
+            1,
+            projection.Split("IoFatSourceWorkspaceService.DescribeAsync", StringSplitOptions.None).Length - 1);
+        Assert.Contains("projection.DescribedSources", bootstrap, StringComparison.Ordinal);
+        Assert.Contains("IoTestWorkspaceBootstrapService.OpenDescribedSourcesAsync", bootstrap, StringComparison.Ordinal);
+        Assert.Contains("OpenDescribedSourcesAsync", bootstrapService, StringComparison.Ordinal);
+        Assert.Contains("IoTestWorkspacePersistence.OpenDescribedSourcesAsync", bootstrapService, StringComparison.Ordinal);
+        Assert.Contains("StageDescribedAsync", persistence, StringComparison.Ordinal);
+        Assert.Contains("CopyVerifiedAsync", sourceWorkspace, StringComparison.Ordinal);
+        Assert.Contains("VerifyHash(bytes, expectedSha256", sourceWorkspace, StringComparison.Ordinal);
+    }
+
     [Fact]
     public void EmbeddedAutomaticBootstrap_NeverHidesEngineeringWindow()
     {

From 3b49206bfebaaeac6a84a3dcae63f3925d0e0bc7 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Fri, 11 Sep 2026 15:08:08 +0700
Subject: [PATCH 82/84] test(fat): align Engineering bootstrap contract with
 described sources

---
 .../ARSAS.Tests/ProductionFatEngineeringTabRegressionTests.cs  | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tests/ARSAS.Tests/ProductionFatEngineeringTabRegressionTests.cs b/tests/ARSAS.Tests/ProductionFatEngineeringTabRegressionTests.cs
index c53331a23..9a80fe0fa 100644
--- a/tests/ARSAS.Tests/ProductionFatEngineeringTabRegressionTests.cs
+++ b/tests/ARSAS.Tests/ProductionFatEngineeringTabRegressionTests.cs
@@ -26,7 +26,8 @@ public void ProductionFatTab_AutoBootstrapsFromSelectedEngineeringStaticDataSet(
         Assert.Contains("DesignModel.DataSets.Sum", source, StringComparison.Ordinal);
         Assert.Contains("IoFatEngineeringWorkspaceProjectionService.BuildAsync", source, StringComparison.Ordinal);
         Assert.Contains("AdoptEngineeringRuntimeWorkspaces", source, StringComparison.Ordinal);
-        Assert.Contains("IoTestWorkspaceBootstrapService.OpenSourcesAsync", source, StringComparison.Ordinal);
+        Assert.Contains("IoTestWorkspaceBootstrapService.OpenDescribedSourcesAsync", source, StringComparison.Ordinal);
+        Assert.Contains("projection.DescribedSources", source, StringComparison.Ordinal);
         Assert.Contains("SynchronizeImportedSclFatWithEngineering", source, StringComparison.Ordinal);
         Assert.Contains("ShowIoTestingWorkspaceAsync", source, StringComparison.Ordinal);
         Assert.Contains("no SCL re-import", source, StringComparison.Ordinal);

From e1c6a6e5872c28340fe0c1442abb6bd92aa119a0 Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Fri, 11 Sep 2026 17:11:06 +0700
Subject: [PATCH 83/84] fix(fat): canonicalize live aliases and speed staged
 reopen

---
 .../IoFatEngineeringSelectionBridge.cs        | 28 ++++++++---
 .../IoTesting/IoFatSourceWorkspaceService.cs  | 48 ++++++++++++++++++-
 Services/IoTesting/IoTestSessionPreflight.cs  |  7 +++
 ...redWorkspaceRuntimeDedupRegressionTests.cs | 12 ++---
 .../ProductionFatP0FieldRegressionTests.cs    | 18 ++++---
 5 files changed, 91 insertions(+), 22 deletions(-)

diff --git a/Services/IoTesting/IoFatEngineeringSelectionBridge.cs b/Services/IoTesting/IoFatEngineeringSelectionBridge.cs
index 785bd8213..08712a485 100644
--- a/Services/IoTesting/IoFatEngineeringSelectionBridge.cs
+++ b/Services/IoTesting/IoFatEngineeringSelectionBridge.cs
@@ -76,7 +76,7 @@ public static int Initialize(
 
                 foreach (var staticPoint in FindStaticDataSetRuntimeCoverage(
                              ied,
-                             manualPoint.ObjectReference,
+                             EffectiveRuntimeReference(manualPoint),
                              manualPoint.FunctionalConstraint))
                 {
                     if (staticPoint.WorkspaceSelected)
@@ -284,8 +284,7 @@ internal static IReadOnlyList<IoTestPointPlan> FindStaticDataSetRuntimeCoverage(
         var requiredFc = functionalConstraint?.Trim() ?? string.Empty;
         return ied.TestPoints
             .Where(IoTestSignalSelectionService.IsSclDataSetAuthority)
-            .Where(point => IoTestLiveBindingService.NormalizeReference(point.ObjectReference)
-                .Equals(runtime, StringComparison.OrdinalIgnoreCase))
+            .Where(point => CoversRuntimeReference(point, runtime))
             .Where(point => requiredFc.Length == 0 ||
                             string.IsNullOrWhiteSpace(point.FunctionalConstraint) ||
                             point.FunctionalConstraint.Equals(requiredFc, StringComparison.OrdinalIgnoreCase))
@@ -337,11 +336,29 @@ private static HashSet<IoTestPointPlan> FindRedundantManualWorkspacePoints(IoTes
             .Where(IoTestSignalSelectionService.IsSclWorkspaceAuthority)
             .Where(point => FindStaticDataSetRuntimeCoverage(
                     ied,
-                    point.ObjectReference,
+                    EffectiveRuntimeReference(point),
                     point.FunctionalConstraint)
                 .Count > 0)
             .ToHashSet();
 
+    private static string EffectiveRuntimeReference(IoTestPointPlan point)
+    {
+        var live = IoTestLiveBindingService.NormalizeReference(point.LiveSignalReference);
+        return live.Length > 0
+            ? live
+            : IoTestLiveBindingService.NormalizeReference(point.ObjectReference);
+    }
+
+    private static bool CoversRuntimeReference(IoTestPointPlan point, string normalizedRuntimeReference)
+    {
+        var live = IoTestLiveBindingService.NormalizeReference(point.LiveSignalReference);
+        if (live.Length > 0 && live.Equals(normalizedRuntimeReference, StringComparison.OrdinalIgnoreCase))
+            return true;
+
+        return IoTestLiveBindingService.NormalizeReference(point.ObjectReference)
+            .Equals(normalizedRuntimeReference, StringComparison.OrdinalIgnoreCase);
+    }
+
     private static bool HasSameRuntimeIdentity(
         IoTestPointPlan point,
         string? runtimeReference,
@@ -349,8 +366,7 @@ private static bool HasSameRuntimeIdentity(
     {
         var runtime = IoTestLiveBindingService.NormalizeReference(runtimeReference);
         if (runtime.Length == 0 ||
-            !IoTestLiveBindingService.NormalizeReference(point.ObjectReference)
-                .Equals(runtime, StringComparison.OrdinalIgnoreCase))
+            !CoversRuntimeReference(point, runtime))
         {
             return false;
         }
diff --git a/Services/IoTesting/IoFatSourceWorkspaceService.cs b/Services/IoTesting/IoFatSourceWorkspaceService.cs
index 10bc5c60f..ad4fa720f 100644
--- a/Services/IoTesting/IoFatSourceWorkspaceService.cs
+++ b/Services/IoTesting/IoFatSourceWorkspaceService.cs
@@ -71,7 +71,12 @@ public static async Task<IReadOnlyList<IoFatWorkspaceSource>> StageDescribedAsyn
             cancellationToken.ThrowIfCancellationRequested();
             var packageEntry = IoFatSourceIdentity.BuildPackageEntry(item.Source);
             var localPath = Path.Combine(sourceDirectory, Path.GetFileName(packageEntry));
-            await CopyVerifiedAsync(item.OriginalPath, localPath, item.Source.Sha256, cancellationToken).ConfigureAwait(false);
+            await CopyVerifiedAsync(
+                item.OriginalPath,
+                localPath,
+                item.Source.Sha256,
+                item.Source.Length,
+                cancellationToken).ConfigureAwait(false);
             staged.Add(new IoFatWorkspaceSource(item.Source, localPath, packageEntry));
         }
         return staged;
@@ -159,13 +164,54 @@ private static async Task CopyVerifiedAsync(
         string sourcePath,
         string destination,
         string expectedSha256,
+        long expectedLength,
         CancellationToken cancellationToken)
     {
+        // The local FAT source path is content-addressed by SourceId/SHA-256. Re-opening the
+        // same Engineering SCL must not rewrite identical bytes on every FAT-tab entry.
+        // Verify the staged copy before reuse; corruption falls back to the normal source
+        // read + SHA-256 verification + atomic replacement path.
+        if (await IsVerifiedStagedCopyAsync(
+                destination,
+                expectedSha256,
+                expectedLength,
+                cancellationToken).ConfigureAwait(false))
+        {
+            return;
+        }
+
         var bytes = await File.ReadAllBytesAsync(sourcePath, cancellationToken).ConfigureAwait(false);
         VerifyHash(bytes, expectedSha256, $"source '{Path.GetFileName(sourcePath)}'");
+        if (expectedLength > 0 && bytes.LongLength != expectedLength)
+            throw new InvalidDataException($"The source '{Path.GetFileName(sourcePath)}' length changed after its FAT identity was described.");
         await WriteFileAtomicAsync(destination, bytes, cancellationToken).ConfigureAwait(false);
     }
 
+    private static async Task<bool> IsVerifiedStagedCopyAsync(
+        string path,
+        string expectedSha256,
+        long expectedLength,
+        CancellationToken cancellationToken)
+    {
+        if (!File.Exists(path))
+            return false;
+
+        var info = new FileInfo(path);
+        if (expectedLength > 0 && info.Length != expectedLength)
+            return false;
+
+        await using var stream = new FileStream(
+            path,
+            FileMode.Open,
+            FileAccess.Read,
+            FileShare.Read,
+            64 * 1024,
+            FileOptions.Asynchronous | FileOptions.SequentialScan);
+        var hash = await SHA256.HashDataAsync(stream, cancellationToken).ConfigureAwait(false);
+        var actual = Convert.ToHexString(hash).ToLowerInvariant();
+        return actual.Equals(expectedSha256, StringComparison.OrdinalIgnoreCase);
+    }
+
     private static ZipArchiveEntry RequiredEntry(ZipArchive archive, string name)
     {
         if (string.IsNullOrWhiteSpace(name) || name.Contains("..", StringComparison.Ordinal) || Path.IsPathRooted(name))
diff --git a/Services/IoTesting/IoTestSessionPreflight.cs b/Services/IoTesting/IoTestSessionPreflight.cs
index 508045120..12f5b287f 100644
--- a/Services/IoTesting/IoTestSessionPreflight.cs
+++ b/Services/IoTesting/IoTestSessionPreflight.cs
@@ -9,6 +9,13 @@ public static IoTestSessionActionResult Validate(IoTestIedPlan? ied)
         if (ied == null)
             return IoTestSessionActionResult.Failure("Select an imported IED first.");
 
+        // Persisted/manual SCL aliases can be restored before live binding proves that an
+        // authoritative Static DataSet row and a manual scalar resolve to the same primary
+        // IEC 61850 leaf. Canonicalize only that shadow alias here, immediately before the
+        // strict duplicate-reference guard. TEST/disposition/evidence are preserved; only
+        // shared workspace ownership moves back to the Static DataSet authority.
+        IoFatEngineeringSelectionBridge.RetireRedundantManualWorkspaceRows(ied);
+
         var unsafeEnabled = ied.TestPoints
             .Where(point => point.WorkspaceSelected && point.IsIncludedInFat && point.TestEnabled && !point.ImportReady)
             .ToList();
diff --git a/tests/ARSAS.Tests/IoFatSharedWorkspaceRuntimeDedupRegressionTests.cs b/tests/ARSAS.Tests/IoFatSharedWorkspaceRuntimeDedupRegressionTests.cs
index bcc01336d..f769e28ac 100644
--- a/tests/ARSAS.Tests/IoFatSharedWorkspaceRuntimeDedupRegressionTests.cs
+++ b/tests/ARSAS.Tests/IoFatSharedWorkspaceRuntimeDedupRegressionTests.cs
@@ -24,21 +24,17 @@ public void RedundantManualRuntimeOverlay_IsRetiredBeforeFatPreflight()
         var manual = ManualPoint(runtime);
         var ied = Ied(staticA, staticB, manual);
 
-        var blocked = IoTestSessionPreflight.Validate(ied);
-        Assert.False(blocked.Succeeded);
-        Assert.Contains("multiple enabled test points", blocked.Message, StringComparison.OrdinalIgnoreCase);
-
-        var retired = IoFatEngineeringSelectionBridge.RetireRedundantManualWorkspaceRows(ied);
+        var ready = IoTestSessionPreflight.Validate(ied);
 
-        Assert.Equal(1, retired);
+        Assert.True(ready.Succeeded, ready.Message);
         Assert.False(manual.WorkspaceSelected);
         Assert.True(manual.TestEnabled);
         Assert.True(manual.IsIncludedInFat);
         Assert.True(staticA.WorkspaceSelected);
         Assert.True(staticB.WorkspaceSelected);
 
-        var ready = IoTestSessionPreflight.Validate(ied);
-        Assert.True(ready.Succeeded, ready.Message);
+        var retired = IoFatEngineeringSelectionBridge.RetireRedundantManualWorkspaceRows(ied);
+        Assert.Equal(0, retired);
     }
 
     [Fact]
diff --git a/tests/ARSAS.Tests/ProductionFatP0FieldRegressionTests.cs b/tests/ARSAS.Tests/ProductionFatP0FieldRegressionTests.cs
index 4368dc587..534f24c09 100644
--- a/tests/ARSAS.Tests/ProductionFatP0FieldRegressionTests.cs
+++ b/tests/ARSAS.Tests/ProductionFatP0FieldRegressionTests.cs
@@ -25,21 +25,23 @@ public void AutomaticStaticDataSetScope_RetiresManualAliasBeforeSessionPreflight
             primaryLiveLeaf);
 
         var ied = Ied(staticPoint, manualAlias);
-        var blocked = IoTestSessionPreflight.Validate(ied);
-        Assert.False(blocked.Succeeded);
-        Assert.Contains("multiple enabled test points", blocked.Message, StringComparison.OrdinalIgnoreCase);
 
-        var retired = IoFatEngineeringSelectionBridge.RetireManualWorkspaceRowsForStaticDataSetMode(ied);
+        // Field regression: a persisted scl-manual-* row may be restored before live
+        // binding proves that both rows collapse to the same primary leaf. Start FAT must
+        // self-heal that stale overlay instead of presenting a scope-not-ready dialog.
+        var ready = IoTestSessionPreflight.Validate(ied);
 
-        Assert.Equal(1, retired);
+        Assert.True(ready.Succeeded, ready.Message);
         Assert.True(staticPoint.WorkspaceSelected);
         Assert.False(manualAlias.WorkspaceSelected);
         Assert.True(manualAlias.TestEnabled);
         Assert.True(manualAlias.IsIncludedInFat);
         Assert.Equal(primaryLiveLeaf, manualAlias.LiveSignalReference);
 
-        var ready = IoTestSessionPreflight.Validate(ied);
-        Assert.True(ready.Succeeded, ready.Message);
+        // The broad automatic-static cleanup is now idempotent because preflight already
+        // retired the exact live-leaf shadow alias without touching evidence/test state.
+        var retired = IoFatEngineeringSelectionBridge.RetireManualWorkspaceRowsForStaticDataSetMode(ied);
+        Assert.Equal(0, retired);
     }
 
     [Fact]
@@ -88,6 +90,8 @@ public void EngineeringBootstrap_ReusesDescribedSourcesWhileStagingStillVerifies
         Assert.Contains("IoTestWorkspacePersistence.OpenDescribedSourcesAsync", bootstrapService, StringComparison.Ordinal);
         Assert.Contains("StageDescribedAsync", persistence, StringComparison.Ordinal);
         Assert.Contains("CopyVerifiedAsync", sourceWorkspace, StringComparison.Ordinal);
+        Assert.Contains("IsVerifiedStagedCopyAsync", sourceWorkspace, StringComparison.Ordinal);
+        Assert.Contains("SHA256.HashDataAsync(stream", sourceWorkspace, StringComparison.Ordinal);
         Assert.Contains("VerifyHash(bytes, expectedSha256", sourceWorkspace, StringComparison.Ordinal);
     }
 

From 399974571c7c0a649f8c4e3806a4e859eeaf1adf Mon Sep 17 00:00:00 2001
From: Ari Sulistiono <ari.sulistiono@gmail.com>
Date: Fri, 11 Sep 2026 17:17:04 +0700
Subject: [PATCH 84/84] test(fat): keep strict duplicate guard coverage after
 alias self-heal

---
 .../ProductionFatEngineeringTabRegressionTests.cs           | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tests/ARSAS.Tests/ProductionFatEngineeringTabRegressionTests.cs b/tests/ARSAS.Tests/ProductionFatEngineeringTabRegressionTests.cs
index 9a80fe0fa..633df0122 100644
--- a/tests/ARSAS.Tests/ProductionFatEngineeringTabRegressionTests.cs
+++ b/tests/ARSAS.Tests/ProductionFatEngineeringTabRegressionTests.cs
@@ -96,11 +96,15 @@ public void ProductionFatSafetyBoundary_KeepsEngineeringAuthorityAndStrictPrefli
     {
         var bootstrapSource = File.ReadAllText(FindRepoFile("MainWindow.ProductionFatEngineeringBootstrap.cs"));
         var fieldRegressionSource = File.ReadAllText(FindRepoFile("tests/ARSAS.Tests/ProductionFatP0FieldRegressionTests.cs"));
+        var preflightSource = File.ReadAllText(FindRepoFile("Services/IoTesting/IoTestSessionPreflight.cs"));
+        var preflightTests = File.ReadAllText(FindRepoFile("tests/ARSAS.Tests/IoTestSessionPreflightTests.cs"));
 
         Assert.Contains("RetireManualWorkspaceRowsForStaticDataSetMode", bootstrapSource, StringComparison.Ordinal);
         Assert.Contains("AutomaticStaticDataSetScope_RetiresManualAliasBeforeSessionPreflight", fieldRegressionSource, StringComparison.Ordinal);
         Assert.Contains("IoTestSessionPreflight.Validate", fieldRegressionSource, StringComparison.Ordinal);
-        Assert.Contains("multiple enabled test points", fieldRegressionSource, StringComparison.OrdinalIgnoreCase);
+        Assert.Contains("RetireRedundantManualWorkspaceRows", preflightSource, StringComparison.Ordinal);
+        Assert.Contains("multiple enabled test points", preflightSource, StringComparison.OrdinalIgnoreCase);
+        Assert.Contains("Validate_RejectsDuplicateEnabledLiveReference", preflightTests, StringComparison.Ordinal);
     }
 
     private static string FindRepoFile(string relativePath)