fix(transport): template diffs resolve folder/base/composition names — unchanged structured templates classify Identical again

#05-T23. ArtifactDiff.CompareTemplate gains optional folderNameById /
templateNameById maps; FolderNameOf / BaseTemplateNameOf / CompositionTargetNameOf
resolve the existing template's FolderId / ParentTemplateId / composition
ComposedTemplateId to real names (falling back to the <id:N> placeholder only
when a map is absent or misses, keeping existing unit-test callers valid).
PreviewAsync builds templateNameById from GetAllTemplatesAsync (parent/composition
targets can be any template, not just bundle-named ones) and threads both maps
through. Fixes spurious Modified on every re-import of a foldered/derived/composed
template. End-to-end preview test + two ArtifactDiff unit tests.

Claude-Session: https://claude.ai/code/session_01MtdgwpEeCUn6cUA5f1LMPj

src/ZB.MOM.WW.ScadaBridge.Transport/Import/ArtifactDiff.cs

@@ -50,8 +50,19 @@ public sealed class ArtifactDiff
     /// </summary>
     /// <param name="incoming">The incoming template from the bundle.</param>
     /// <param name="existing">The existing template in the database, or null if new.</param>
+    /// <param name="folderNameById">Optional folder-id→name map so an existing template's
+    /// <c>FolderId</c> resolves to the same name the bundle carries; without it, folder
+    /// identity falls back to a <c>&lt;id:N&gt;</c> placeholder that never matches a bundle
+    /// name (spurious Modified on every re-import — #05-T23).</param>
+    /// <param name="templateNameById">Optional template-id→name map resolving the existing
+    /// template's <c>ParentTemplateId</c> (base) and each composition's <c>ComposedTemplateId</c>
+    /// to names, with the same placeholder fallback semantics.</param>
     /// <returns>An import preview item describing the conflict type and differences.</returns>
-    public ImportPreviewItem CompareTemplate(TemplateDto incoming, Template? existing)
+    public ImportPreviewItem CompareTemplate(
+        TemplateDto incoming,
+        Template? existing,
+        IReadOnlyDictionary<int, string>? folderNameById = null,
+        IReadOnlyDictionary<int, string>? templateNameById = null)
     {
         ArgumentNullException.ThrowIfNull(incoming);
         if (existing is null)
@@ -61,8 +72,8 @@ public sealed class ArtifactDiff
 
         var changes = new List<FieldChange>();
         AddIfDifferent(changes, "Description", existing.Description, incoming.Description);
-        AddIfDifferent(changes, "FolderName", FolderNameOf(existing), incoming.FolderName);
-        AddIfDifferent(changes, "BaseTemplateName", BaseTemplateNameOf(existing), incoming.BaseTemplateName);
+        AddIfDifferent(changes, "FolderName", FolderNameOf(existing, folderNameById), incoming.FolderName);
+        AddIfDifferent(changes, "BaseTemplateName", BaseTemplateNameOf(existing, templateNameById), incoming.BaseTemplateName);
 
         // Bundles reference the alarm on-trigger script by name; resolve the
         // persisted FK back to a name over this template's own scripts so the
@@ -104,7 +115,7 @@ public sealed class ArtifactDiff
             incoming.Compositions,
             e => e.InstanceName,
             i => i.InstanceName,
-            (e, i) => CompositionTargetNameOf(e) == i.ComposedTemplateName,
+            (e, i) => CompositionTargetNameOf(e, templateNameById) == i.ComposedTemplateName,
             "Compositions",
             changes);
 
@@ -665,24 +676,28 @@ public sealed class ArtifactDiff
         && e.ParameterDefinitions == i.ParameterDefinitions
         && e.ReturnDefinition == i.ReturnDefinition;
 
-    private static string? FolderNameOf(Template t)
+    private static string? FolderNameOf(Template t, IReadOnlyDictionary<int, string>? folderNameById)
     {
         // Templates carry only a FK to the folder; the EntitySerializer projects
-        // it to a name. The diff doesn't have access to a folder lookup at
-        // CompareTemplate scope, so fall back to "<id:N>" when only the id is
-        // known. The PreviewAsync caller can pass a hydrated Template (via
-        // GetTemplateWithChildrenAsync) and the folder name typically isn't on
-        // it — this branch is a deliberate best-effort.
-        return t.FolderId is null ? null : $"<id:{t.FolderId}>";
+        // it to a name. When PreviewAsync supplies a folder-id→name map (#05-T23)
+        // the id resolves to the real name so an unchanged folder assignment reads
+        // Identical; without the map (or on a miss) we fall back to "<id:N>", which
+        // keeps the older unit-test callers valid but never matches a bundle name.
+        if (t.FolderId is null) return null;
+        if (folderNameById != null && folderNameById.TryGetValue(t.FolderId.Value, out var name)) return name;
+        return $"<id:{t.FolderId}>";
     }
 
-    private static string? BaseTemplateNameOf(Template t)
+    private static string? BaseTemplateNameOf(Template t, IReadOnlyDictionary<int, string>? templateNameById)
     {
-        return t.ParentTemplateId is null ? null : $"<id:{t.ParentTemplateId}>";
+        if (t.ParentTemplateId is null) return null;
+        if (templateNameById != null && templateNameById.TryGetValue(t.ParentTemplateId.Value, out var name)) return name;
+        return $"<id:{t.ParentTemplateId}>";
     }
 
-    private static string CompositionTargetNameOf(TemplateComposition comp)
+    private static string CompositionTargetNameOf(TemplateComposition comp, IReadOnlyDictionary<int, string>? templateNameById)
     {
+        if (templateNameById != null && templateNameById.TryGetValue(comp.ComposedTemplateId, out var name)) return name;
         return $"<id:{comp.ComposedTemplateId}>";
     }
 

src/ZB.MOM.WW.ScadaBridge.Transport/Import/BundleImporter.cs

@@ -392,10 +392,17 @@ public sealed class BundleImporter : IBundleImporter
             .ConfigureAwait(false);
         var hydratedByName = hydratedTemplates
             .ToDictionary(t => t.Name, t => t, StringComparer.Ordinal);
+        // #05-T23: a template's ParentTemplateId (base) and each composition's
+        // ComposedTemplateId point at ANY template in the DB (not just the ones
+        // whose names the bundle carries), so resolve names through the full
+        // template set. Without this map the diff compares "<id:N>" placeholders
+        // against real bundle names and reports spurious Modified.
+        var allTemplateStubs = await _templateRepo.GetAllTemplatesAsync(ct).ConfigureAwait(false);
+        var templateNameById = allTemplateStubs.ToDictionary(t => t.Id, t => t.Name);
         foreach (var tDto in content.Templates)
         {
             hydratedByName.TryGetValue(tDto.Name, out var existing);
-            items.Add(_diff.CompareTemplate(tDto, existing));
+            items.Add(_diff.CompareTemplate(tDto, existing, folderNameById, templateNameById));
         }
 
         // ---- SharedScripts ----

tests/ZB.MOM.WW.ScadaBridge.Transport.IntegrationTests/Import/BundleImporterPreviewTests.cs

@@ -330,6 +330,51 @@ public sealed class BundleImporterPreviewTests : IDisposable
         Assert.Null(pumpItem.FieldDiffJson);
     }
 
+    [Fact]
+    public async Task PreviewAsync_unchanged_structured_template_classifies_Identical()
+    {
+        // #05-T23 end-to-end: a template with a base (ParentTemplateId) and a
+        // composition, re-imported against an UNCHANGED target, must classify
+        // Identical. Before T23, PreviewAsync compared "<id:N>" placeholders for
+        // BaseTemplateName / composition target against the bundle's real names,
+        // so it always read Modified — defeating the wizard's auto-skip contract.
+        await using (var scope = _provider.CreateAsyncScope())
+        {
+            var ctx = scope.ServiceProvider.GetRequiredService<ScadaBridgeDbContext>();
+            ctx.Templates.Add(new Template("BasePump") { Description = "base" });
+            ctx.Templates.Add(new Template("FeatureX") { Description = "feature" });
+            await ctx.SaveChangesAsync();
+            var basePump = await ctx.Templates.SingleAsync(t => t.Name == "BasePump");
+            var feature = await ctx.Templates.SingleAsync(t => t.Name == "FeatureX");
+
+            var pump = new Template("Pump") { Description = "derived", ParentTemplateId = basePump.Id };
+            ctx.Templates.Add(pump);
+            await ctx.SaveChangesAsync();
+            pump.Compositions.Add(new TemplateComposition("mod1")
+            {
+                TemplateId = pump.Id,
+                ComposedTemplateId = feature.Id,
+            });
+            await ctx.SaveChangesAsync();
+        }
+
+        // Export everything; do NOT wipe — the target is unchanged.
+        var bundleStream = await ExportTemplatesAsync();
+        var bytes = await StreamToBytes(bundleStream);
+
+        ImportPreview preview;
+        await using (var scope = _provider.CreateAsyncScope())
+        {
+            var importer = scope.ServiceProvider.GetRequiredService<IBundleImporter>();
+            var session = await importer.LoadAsync(new MemoryStream(bytes), passphrase: null);
+            preview = await importer.PreviewAsync(session.SessionId);
+        }
+
+        var pumpItem = Assert.Single(preview.Items,
+            i => i.EntityType == "Template" && i.Name == "Pump");
+        Assert.Equal(ConflictKind.Identical, pumpItem.Kind);
+    }
+
     [Fact]
     public async Task PreviewAsync_emits_Warning_when_template_script_dependency_missing()
     {

tests/ZB.MOM.WW.ScadaBridge.Transport.Tests/Import/ArtifactDiffTests.cs

@@ -150,6 +150,52 @@ public sealed class ArtifactDiffTests
         Assert.Contains(("add", "new2"), hunks);
     }
 
+    // ============ #05-T23: placeholder-identity resolution via name maps ============
+
+    [Fact]
+    public void CompareTemplate_MatchingFolderBaseAndComposition_IsIdentical()
+    {
+        // A structured template (FolderId, ParentTemplateId, one composition) that
+        // the incoming bundle matches by NAME must classify Identical. Before T23,
+        // FolderNameOf/BaseTemplateNameOf/CompositionTargetNameOf returned "<id:N>"
+        // placeholders that never equalled the incoming names, so every re-import
+        // of an unchanged structured template spuriously read Modified.
+        var existing = MakeTemplate("Pump");
+        existing.FolderId = 5;
+        existing.ParentTemplateId = 7;
+        existing.Compositions.Add(new TemplateComposition("Mod1") { ComposedTemplateId = 9 });
+
+        var folderNameById = new Dictionary<int, string> { [5] = "Machines" };
+        var templateNameById = new Dictionary<int, string> { [7] = "BasePump", [9] = "FeatureX" };
+
+        var incoming = MakeTemplateDto("Pump") with
+        {
+            FolderName = "Machines",
+            BaseTemplateName = "BasePump",
+            Compositions = new[] { new TemplateCompositionDto("Mod1", "FeatureX") },
+        };
+
+        var item = _diff.CompareTemplate(incoming, existing, folderNameById, templateNameById);
+
+        Assert.Equal(ConflictKind.Identical, item.Kind);
+    }
+
+    [Fact]
+    public void CompareTemplate_DivergentBaseTemplateName_IsModified()
+    {
+        // Sanity: the maps must not mask a REAL change. Existing base = "BasePump",
+        // incoming names a different base → Modified.
+        var existing = MakeTemplate("Pump");
+        existing.ParentTemplateId = 7;
+        var templateNameById = new Dictionary<int, string> { [7] = "BasePump" };
+
+        var incoming = MakeTemplateDto("Pump") with { BaseTemplateName = "DifferentBase" };
+
+        var item = _diff.CompareTemplate(incoming, existing, folderNameById: null, templateNameById: templateNameById);
+
+        Assert.Equal(ConflictKind.Modified, item.Kind);
+    }
+
     // ============ #05-T6: single-source child equality — diff sees the full field set ============
 
     [Fact]