From e87eebefd1b263040d02ba3f0785ea451ebcdb85 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Steinhagen?=
 <88777268+bjoernsteinhagen@users.noreply.github.com>
Date: Wed, 4 Feb 2026 17:13:17 +0200
Subject: [PATCH] fix(revit): prevent unpacking of internal unexpected elements
 in groups (#1266)
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* feat(revit): filter out sketch lines from grouped elements

* fix(revit): exclude internal definitions (types/masses) from group unpacking

* perf(revit): optimize group unpacking with FilteredElementCollector

* chore(revit): remove unused method after refactor

---------

Co-authored-by: Oğuzhan Koral <45078678+oguzhankoral@users.noreply.github.com>
---
 .../HostApp/ElementUnpacker.cs                | 35 +++++++++++++++----
 1 file changed, 28 insertions(+), 7 deletions(-)

diff --git a/Connectors/Revit/Speckle.Connectors.RevitShared/HostApp/ElementUnpacker.cs b/Connectors/Revit/Speckle.Connectors.RevitShared/HostApp/ElementUnpacker.cs
index f78622879..fd7e2eb73 100644
--- a/Connectors/Revit/Speckle.Connectors.RevitShared/HostApp/ElementUnpacker.cs
+++ b/Connectors/Revit/Speckle.Connectors.RevitShared/HostApp/ElementUnpacker.cs
@@ -9,8 +9,19 @@ namespace Speckle.Connectors.Revit.HostApp;
 /// </summary>
 public class ElementUnpacker
 {
+  private static readonly List<BuiltInCategory> s_skippedCategories =
+  [
+    BuiltInCategory.OST_SketchLines,
+    BuiltInCategory.OST_MassForm,
+    BuiltInCategory.OST_StairsSketchBoundaryLines,
+    BuiltInCategory.OST_StairsSketchLandingCenterLines,
+    BuiltInCategory.OST_StairsSketchRiserLines,
+    BuiltInCategory.OST_RebarSketchLines,
+    BuiltInCategory.OST_StairsSketchRunLines
+  ];
+
   /// <summary>
-  /// Unpacks a random set of revit objects into atomic objects. It currently unpacks groups recurisvely, nested families into atomic family instances.
+  /// Unpacks a random set of revit objects into atomic objects. It currently unpacks groups recursively, nested families into atomic family instances.
   /// This method will also "pack" curtain walls if necessary (ie, if mullions or panels are selected without their parent curtain wall, they are sent independently; if the parent curtain wall is selected, they will be removed out as the curtain wall will include all its children).
   /// </summary>
   /// <param name="selectionElements"></param>
@@ -32,7 +43,7 @@ public class ElementUnpacker
   }
 
   /// <summary>
-  /// Unpacks input element ids into their subelements, eg groups and nested family instances
+  /// Unpacks input element ids into their sub-elements, eg groups and nested family instances
   /// </summary>
   /// <param name="objectIds"></param>
   /// <returns></returns>
@@ -57,11 +68,21 @@ public class ElementUnpacker
       // UNPACK: Groups
       if (element is Group g)
       {
-        // When a group is from a linked model, GetMemberIds may behave differently
-        // We add null checks to handle cases where elements can't be properly resolved
-        // POC: this might screw up generating hosting rel generation here, because nested families in groups get flattened out by GetMemberIds().
-        var groupElements = g.GetMemberIds().Select(doc.GetElement).Where(el => el != null);
-        unpackedElements.AddRange(UnpackElements(groupElements, doc));
+        var memberIds = g.GetMemberIds();
+
+        if (memberIds.Count <= 0)
+        {
+          continue;
+        }
+
+        // using a collector more efficient
+        using var collector = new FilteredElementCollector(doc, memberIds);
+        collector.WhereElementIsNotElementType(); // exclude "Type" elements (FamilySymbols)
+        var filter = new ElementMulticategoryFilter(s_skippedCategories, inverted: true); // exclude "Sketch/Form" categories
+        collector.WherePasses(filter);
+
+        // recursively unpack the valid results
+        unpackedElements.AddRange(UnpackElements(collector, doc));
       }
       else if (element is BaseArray baseArray)
       {