IED Browser: ARSAS-specific IEC 61850 navigation order (UI-only)

Models/IedBrowserPresentation.cs

@@ -372,7 +372,7 @@
         string? iedName = null,
         LiveIedModelDiscoveryDocument? sclModel = null)
     {
         const int childDepth = 1;
         // Keep domain/object keys untouched; only presentation labels are short.
         var labelIed = !string.IsNullOrWhiteSpace(model?.IedName)
             ? model.IedName : iedName;
@@ -380,16 +380,12 @@
             Func<IReadOnlyList<IedBrowserTreeRow>> children)
             => new("category/" + key, name, "Category", 0, loadChildren: children);
 
+        // ARSAS navigation order is a presentation choice, not a wire/model contract.
+        // Stable category keys and lazy children preserve existing selected paths and
+        // avoid any additional MMS discovery, control or report requests.
         var categories = new List<IedBrowserTreeRow>
         {
-            Category("GOOSE", "goose", () => BlockGroups(
-                IedBrowserGooseDirectory.Resolve(model, sclModel), "GoCB", labelIed)),
             Category("Reports", "reports", () => ReportGroups(rcbs, labelIed)),
-            Category("Setting Groups", "settings", () => BlockGroups(model?.SettingGroupControls, "SGCB", labelIed)),
-            // Files inventory belongs exclusively in the right-side
-            // virtualized grid. Nested file nodes duplicate content and
-            // inflate the compact engineering navigation.
-            new("category/files", "Files", "Category", 0),
             Category("DataSets", "datasets", () => DataSetGroups(model?.DataSets, labelIed)),
             Category("Data Model", "model", () =>
                 model?.LogicalDevices.Select(ld =>
@@ -405,7 +401,14 @@
                                             new IedBrowserTreeRow("model/da/" + attr.MmsReference + "/" + ordinal,
                                                 attr.AttributePath, "DA", 4, attr)).ToArray()))
                                     .ToArray())).ToArray())).ToArray()
-                    ?? Array.Empty<IedBrowserTreeRow>())
+                    ?? Array.Empty<IedBrowserTreeRow>()),
+            // Files inventory belongs exclusively in the right-side
+            // virtualized grid. Nested file nodes duplicate content and
+            // inflate the compact engineering navigation.
+            new("category/files", "Files", "Category", 0),
+            Category("GOOSE", "goose", () => BlockGroups(
+                IedBrowserGooseDirectory.Resolve(model, sclModel), "GoCB", labelIed)),
+            Category("Setting Groups", "settings", () => BlockGroups(model?.SettingGroupControls, "SGCB", labelIed))
         };
         return categories; // ARSAS IED Explorer already owns device selection; never duplicate it.
     }

tests/ARSAS.Tests/IedBrowserPresentationTests.cs

@@ -141,9 +141,19 @@ public void CategoriesFollowEngineeringNavigationOrder_WithoutMmsCalls()
         var projection = new IedBrowserTreeProjection();
         projection.Reset(roots);
         Assert.Equal(
-            ["GOOSE", "Reports", "Setting Groups", "Files", "DataSets", "Data Model"],
+            ["Reports", "DataSets", "Data Model", "Files", "GOOSE", "Setting Groups"],
             projection.Rows.Select(x => x.Title).ToArray());
+        Assert.Equal(
+            ["category/reports", "category/datasets", "category/model",
+             "category/files", "category/goose", "category/settings"],
+            projection.Rows.Select(x => x.Key).ToArray());
         Assert.All(projection.Rows, x => Assert.Equal(0, x.Depth));
+
+        // A disconnected or SCL-only session retains the same category routes;
+        // reordering must not depend on live MMS or create placeholder children.
+        var withoutLiveModel = IedBrowserPresentation.Roots(null, Array.Empty<RcbExportRow>());
+        Assert.Equal(projection.Rows.Select(x => x.Key).ToArray(),
+            withoutLiveModel.Select(x => x.Key).ToArray());
     }
 
     [Fact]

tests/ARSAS.Tests/P0BrowserRcbEnabledTruthTests.cs

@@ -123,8 +123,8 @@ public void VirtualTreeStartsWithExactlySixCollapsedCategories()
         var rows = IedBrowserPresentation.Roots(null, [Rcb()]);
         var tree = new IedBrowserTreeProjection();
         tree.Reset(rows);
-        Assert.Equal(new[] { "GOOSE", "Reports", "Setting Groups", "Files",
-            "DataSets", "Data Model" }, tree.Rows.Select(x => x.Title));
+        Assert.Equal(new[] { "Reports", "DataSets", "Data Model", "Files",
+            "GOOSE", "Setting Groups" }, tree.Rows.Select(x => x.Title));
         Assert.All(tree.Rows, x => Assert.False(x.IsExpanded));
 
         var reports = Assert.Single(tree.Rows.Where(x => x.Key == "category/reports"));