Bonsai: implement Add Derived Unit in the units UI (#2554)

The IfcDerivedUnit branch of the Add Unit panel was a literal
`pass  # TODO`, so derived units (velocity, thermal conductance, etc.)
could not be created from the UI even though
ifcopenshell.api.unit.add_derived_unit already supports them.

Add the missing flow, mirroring the module's existing add-unit patterns:
- UnitsData caches derived_unit_types (IfcDerivedUnitEnum from the schema,
  USERDEFINED excluded since it additionally requires a UserDefinedType)
  and named_units (the project's existing IfcNamedUnits, labelled with
  their full unit name and unit type).
- A DerivedUnitElement property group (unit enum + integer exponent) and a
  derived_unit_elements collection on BIMUnitProperties.
- Operators to add/remove element rows and AddDerivedUnit, which validates
  (at least one element per the schema's SET [1:?], no unselected unit, no
  duplicate units), builds the {named unit: exponent} mapping, and calls
  core.add_derived_unit -> unit.add_derived_unit; rows are cleared on
  success.
- The panel draws the type dropdown, per-row unit/exponent/remove controls,
  and an Add Element button.

Verified live in headless Blender with the real operators: metre^1 x
second^-1 with LINEARVELOCITYUNIT creates
IfcDerivedUnit((IfcDerivedUnitElement(metre,1), IfcDerivedUnitElement(
second,-1)), .LINEARVELOCITYUNIT.), assignable via bim.assign_unit; the
empty-rows and duplicate-unit error paths report cleanly; existing SI and
monetary unit flows are unaffected. Core test_unit.py: 19 passed
(includes a new TestAddDerivedUnit).

Maintainer context: Moult invited an implementation on the issue
("Indeed I couldn't think of a nice UI for it, go for it!").

Generated with the assistance of an AI coding tool.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.gitignore

@@ -127,6 +127,7 @@ src/ifcopenshell-python/ifcopenshell/express/*.exp.cache.dat
 
 # temp files from AI coding tools
 *.claude
+CLAUDE.local.md
 *.py.tmp*
 *.json.tmp*
 

cmake/CMakeLists.txt

@@ -27,13 +27,14 @@ endif()
 set(CMAKE_CXX_STANDARD_REQUIRED ON) # not necessary, but encouraged
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 
-if(VERSION_OVERRIDE)
-    file(READ "../VERSION" "RELEASE_VERSION_")
-    string(STRIP "${RELEASE_VERSION_}" RELEASE_VERSION)
-    message(STATUS "Detected version '${RELEASE_VERSION}'")
-else()
-    set(RELEASE_VERSION "0.8.0")
-endif()
+# The VERSION file in the repository root is the single source of truth for the
+# release version. Read it unconditionally so a plain source build reports the
+# real version through buildinfo.cpp instead of the stale hardcoded 0.8.0
+# fallback (see #8164). VERSION_OVERRIDE still controls the branch name used
+# when ADD_COMMIT_SHA embeds a commit sha.
+file(READ "../VERSION" "RELEASE_VERSION_")
+string(STRIP "${RELEASE_VERSION_}" RELEASE_VERSION)
+message(STATUS "Detected version '${RELEASE_VERSION}'")
 
 add_definitions(-D_DISABLE_CONSTEXPR_MUTEX_CONSTRUCTOR)
 
@@ -313,8 +314,12 @@ if(WASM_BUILD)
 else()
     # @todo review this, shouldn't this be all possible header-only now?
     # ... or rewritten using C++17 features?
+    # Boost.System has been header-only since 1.69 and its compiled stub library
+    # was dropped in newer Boost, so requesting it as a component makes
+    # find_package fail on Boost 1.70 and up (for example Boost 1.90). It is
+    # still pulled in transitively by thread / iostreams where needed, so do not
+    # request it explicitly.
     set(BOOST_COMPONENTS
-        system
         program_options
         regex
         thread
@@ -660,6 +665,11 @@ if(ADD_COMMIT_SHA)
     endif()
 endif(ADD_COMMIT_SHA)
 
+# Always expose the release version (from the VERSION file) to buildinfo.cpp so
+# that a build without commit-sha info reports the correct version instead of a
+# stale hardcoded fallback. See #8164.
+target_compile_definitions(IfcParse PRIVATE IFCOPENSHELL_VERSION_STRING=${RELEASE_VERSION})
+
 if(MSVC)
     # @todo still needs to be understood better, but the cgal and cgal-simple kernel cause multiply defined boost lambda placeholders _1 ... _3
     set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} /FORCE:MULTIPLE")

src/bonsai/bonsai/bim/handler.py

@@ -320,9 +320,11 @@ def loadIfcStore(scene: bpy.types.Scene) -> None:
     IfcStore.purge()
     refresh_ui_data()
     if not tool.Ifc.get():
+        tool.Autosave.cancel_timer()
         return
     tool.Ifc.schema()
     IfcStore.relink_all_objects()
+    tool.Autosave.reset_timer()
 
 
 @persistent

src/bonsai/bonsai/bim/module/drawing/gizmos.py

@@ -82,7 +82,15 @@ import math
 from collections.abc import Callable, Iterator
 from dataclasses import dataclass
 from enum import Enum
-from typing import Any, ClassVar, Literal, Optional, Protocol, runtime_checkable
+from typing import (
+    TYPE_CHECKING,
+    Any,
+    ClassVar,
+    Literal,
+    Optional,
+    Protocol,
+    runtime_checkable,
+)
 
 import blf
 import bpy
@@ -105,6 +113,9 @@ from mathutils.kdtree import KDTree
 import bonsai.tool as tool
 from bonsai.bim.module.drawing.shaders import ExtrusionGuidesShader
 
+if TYPE_CHECKING:
+    import bmesh
+
 SNAP_POINT_SIZE = 10.0
 SNAP_POINT_COLOR = (1.0, 0.5, 0.0, 1.0)
 SNAP_MAX_RADIUS = 50.0
@@ -2035,7 +2046,9 @@ class TexturedQuadGizmoMixin(StaticTrisGizmoMixin):
 
     def setup(self) -> None:
         super().setup()
-        from bonsai.bim.module.drawing import gizmo_textures
+        from bonsai.bim.module.drawing import (
+            gizmo_textures,  # ty: ignore[unresolved-import]
+        )
 
         self._quad_batch = batch_for_shader(
             gizmo_textures.get_shader(),
@@ -2044,7 +2057,9 @@ class TexturedQuadGizmoMixin(StaticTrisGizmoMixin):
         )
 
     def draw(self, context: bpy.types.Context) -> None:
-        from bonsai.bim.module.drawing import gizmo_textures
+        from bonsai.bim.module.drawing import (
+            gizmo_textures,  # ty: ignore[unresolved-import]
+        )
 
         texture = gizmo_textures.get_icon_texture(self.icon_name)
         if texture is None:

src/bonsai/bonsai/bim/module/drawing/operator.py

@@ -951,6 +951,12 @@ class CreateDrawing(bpy.types.Operator):
         tree = ifcopenshell.geom.tree()
         tree.enable_face_styles(True)
 
+        # Accumulated across every file in the loop below (main model plus any
+        # linked models) so the SHAPELY fill pass after the loop covers all of
+        # them, not just whichever file happened to be processed last.
+        raycast_objs = set()
+        elements_with_faces = set()
+
         for ifc_path, (ifc, link_matrix) in files.items():
             # Don't use draw.main() just whilst we're prototyping and experimenting
             # TODO: hash paths are never used
@@ -960,13 +966,24 @@ class CreateDrawing(bpy.types.Operator):
             self.serialiser.setFile(ifc)
             drawing_elements = tool.Drawing.get_drawing_elements(self.camera_element, ifc_file=ifc)
 
+            if self.cprops.fill_mode == "SHAPELY":
+                for element in drawing_elements.copy():
+                    if element.is_a("IfcAnnotation"):
+                        continue
+                    obj = tool.Ifc.get_object(element)
+                    if obj and obj.type == "MESH" and len(obj.data.polygons):
+                        elements_with_faces.add(element.GlobalId)
+                        raycast_objs.add(obj)
+
             # Get all representation contexts to see what we're dealing with.
             # Drawings only draw bodies and annotations (and facetation, due to a Revit bug).
             # A drawing prioritises a target view context first, followed by a model view context as a fallback.
             # Specifically for PLAN_VIEW and REFLECTED_PLAN_VIEW, any Plan context is also prioritised.
             contexts = self.get_linework_contexts(ifc, target_view)
             self.serialize_contexts_elements(ifc, tree, contexts, "body", drawing_elements, target_view, link_matrix)
-            self.serialize_contexts_elements(ifc, tree, contexts, "annotation", drawing_elements, target_view, link_matrix)
+            self.serialize_contexts_elements(
+                ifc, tree, contexts, "annotation", drawing_elements, target_view, link_matrix
+            )
 
             if tool.Ifc.get() == ifc and self.camera_element not in drawing_elements:
                 with profile("Camera element"):
@@ -1033,16 +1050,6 @@ class CreateDrawing(bpy.types.Operator):
             # shapely variant
             group = root.find("{http://www.w3.org/2000/svg}g")
 
-            raycast_objs = set()
-            elements_with_faces = set()
-            for element in drawing_elements.copy():
-                if element.is_a("IfcAnnotation"):
-                    continue
-                obj = tool.Ifc.get_object(element)
-                if obj and obj.type == "MESH" and len(obj.data.polygons):
-                    elements_with_faces.add(element.GlobalId)
-                    raycast_objs.add(obj)
-
             projections = root.xpath(
                 ".//svg:g[contains(@class, 'projection')]", namespaces={"svg": "http://www.w3.org/2000/svg"}
             )
@@ -2336,7 +2343,9 @@ class ActivateDrawingBase(tool.Ifc.Operator):
         "Activates the selected drawing view.\n\n"
         + "ALT+CLICK to keep the viewport position.\n\n"
         + "SHIFT+CLICK to load a quick preview of the drawing view.\n\n"
-        + "SHIFT+CTRL+CLICK to load the annotations of all selected drawings without switching views"
+        + "SHIFT+CTRL+CLICK to load the annotations of all selected drawings without switching views, "
+        + "then select their cameras (the first selected drawing's camera becomes active).\n\n"
+        + "SHIFT+CTRL+ALT+CLICK to do the same but also select the annotations, not just the cameras"
     )
 
     drawing: bpy.props.IntProperty()
@@ -2358,16 +2367,25 @@ class ActivateDrawingBase(tool.Ifc.Operator):
         default=False,
         options={"SKIP_SAVE"},
     )
+    include_annotations_in_selection: bpy.props.BoolProperty(
+        name="Include Annotations In Selection",
+        description="Also select the loaded annotation objects, not just the drawing cameras.",
+        default=False,
+        options={"SKIP_SAVE"},
+    )
 
     if TYPE_CHECKING:
         drawing: int
         should_view_from_camera: bool
         use_quick_preview: bool
         load_selected_annotations: bool
+        include_annotations_in_selection: bool
 
     def invoke(self, context, event) -> set["rna_enums.OperatorReturnItems"]:
         if event.type == "LEFTMOUSE" and event.shift and event.ctrl:
             self.load_selected_annotations = True
+            if event.alt:
+                self.include_annotations_in_selection = True
             return self.execute(context)
         if event.type == "LEFTMOUSE" and event.alt:
             self.should_view_from_camera = False
@@ -2382,15 +2400,34 @@ class ActivateDrawingBase(tool.Ifc.Operator):
             bpy.ops.bim.load_drawings()
 
         if self.load_selected_annotations:
+            objs_to_select = []
+            active_camera = None
             for d in props.drawings:
                 if not (d.is_drawing and d.is_selected):
                     continue
                 selected_drawing = tool.Ifc.get().by_id(d.ifc_definition_id)
                 # Importing the camera (if missing) ensures the drawing's
                 # collection exists so the annotations get collected into it.
-                if not tool.Ifc.get_object(selected_drawing):
-                    tool.Drawing.import_drawing(selected_drawing)
-                tool.Drawing.import_annotations_in_group(tool.Drawing.get_drawing_group(selected_drawing))
+                if not (camera := tool.Ifc.get_object(selected_drawing)):
+                    camera = tool.Drawing.import_drawing(selected_drawing)
+                group = tool.Drawing.get_drawing_group(selected_drawing)
+                tool.Drawing.import_annotations_in_group(group)
+
+                if active_camera is None:
+                    active_camera = camera
+                objs_to_select.append(camera)
+                if self.include_annotations_in_selection:
+                    for element in tool.Drawing.get_group_elements(group) or []:
+                        if element.is_a("IfcAnnotation") and element.ObjectType != "DRAWING":
+                            if annotation_obj := tool.Ifc.get_object(element):
+                                objs_to_select.append(annotation_obj)
+
+            # Select the checked drawings' objects, with the first drawing's camera as active.
+            bpy.ops.object.select_all(action="DESELECT")
+            for obj in objs_to_select:
+                obj.select_set(True)
+            if active_camera is not None:
+                context.view_layer.objects.active = active_camera
             return {"FINISHED"}
 
         drawing = tool.Ifc.get().by_id(self.drawing)
@@ -2479,7 +2516,9 @@ class ActivateDrawing(bpy.types.Operator, ActivateDrawingBase):
         "Activates the selected drawing view.\n\n"
         + "ALT+CLICK to keep the viewport position.\n\n"
         + "SHIFT+CLICK to load a quick preview of the drawing view.\n\n"
-        + "SHIFT+CTRL+CLICK to load the annotations of all selected drawings without switching views"
+        + "SHIFT+CTRL+CLICK to load the annotations of all selected drawings without switching views, "
+        + "then select their cameras (the first selected drawing's camera becomes active).\n\n"
+        + "SHIFT+CTRL+ALT+CLICK to do the same but also select the annotations, not just the cameras"
     )
 
 

src/bonsai/bonsai/bim/module/model/__init__.py

@@ -27,6 +27,7 @@ import bonsai.tool as tool
 from . import (
     array,
     covering,
+    decorator,
     door,
     external,
     grid,

src/bonsai/bonsai/bim/module/model/array.py

@@ -329,6 +329,7 @@ class _ArrayEditMixin(ParametricEditMixinBase):
         # Unhide the (possibly newly-regenerated) children so the user sees
         # the committed result. Mirrors the hide in ``_enable_one``.
         cls._set_children_visibility(element, hidden=False)
+        tool.Array.select_only_parent(obj, context)
 
     @classmethod
     def _cancel_one(cls, obj: bpy.types.Object) -> None:
@@ -421,9 +422,9 @@ class RegenerateArray(bpy.types.Operator, tool.Ifc.Operator):
         pset = ifcopenshell.util.element.get_pset(parent_element, "BBIM_Array")
         arrays = json.loads(pset["Data"])
         pset = tool.Ifc.get().by_id(pset["id"])
-        # Coalesce host recuts: the child-delete loop, the regenerate, and the
-        # per-child opening mirror all touch the same host body. Without batching,
-        # an N-child wipe-then-regen costs N+1 recuts; this collapses to one.
+        # Coalesce host recuts across the child-delete loop, the regenerate,
+        # and the per-child opening mirror: each fans out its own host body
+        # recut without the batch wrapper.
         with tool.Geometry.batch_host_recut():
             for array in arrays:
                 for child in set(array["children"]):
@@ -442,6 +443,8 @@ class RegenerateArray(bpy.types.Operator, tool.Ifc.Operator):
             tool.Model.regenerate_array(parent, arrays)
             tool.Array.constrain_children_to_parent(parent_element)
 
+        tool.Array.select_only_parent(parent, context)
+
 
 class RemoveArray(bpy.types.Operator, tool.Ifc.Operator):
     bl_idname = "bim.remove_array"

src/bonsai/bonsai/bim/module/model/mep.py

@@ -38,6 +38,7 @@ import numpy as np
 from ifcopenshell.util.shape_builder import ShapeBuilder
 from mathutils import Matrix, Vector
 
+import bonsai.core.geometry
 import bonsai.core.root
 import bonsai.tool as tool
 from bonsai.bim.module.drawing import gizmos as gizmo
@@ -1677,6 +1678,11 @@ def _n_mep_selected(n: int) -> bool:
         element = tool.Ifc.get_entity(selected_obj)
         if element is None or not tool.System.is_mep_element(element):
             return False
+        # Array children mirror their parent's port topology. Writable MEP
+        # actions on a child get wiped by the next array regen, so gate the
+        # icons out at the visibility layer.
+        if tool.Array.is_array_child(element):
+            return False
     return True
 
 
@@ -2555,6 +2561,8 @@ def _active_is_flow_segment(obj: bpy.types.Object) -> bool:
     element = tool.Ifc.get_entity(obj)
     if element is None or not element.is_a("IfcFlowSegment"):
         return False
+    if tool.Array.is_array_child(element):
+        return False
     return tool.System.has_parametric_body(element)
 
 
@@ -2584,6 +2592,8 @@ def _active_is_bend_fitting(obj: bpy.types.Object) -> bool:
     element = tool.Ifc.get_entity(obj)
     if not _is_bend_fitting(element):
         return False
+    if tool.Array.is_array_child(element):
+        return False
     element_type = ifcopenshell.util.element.get_type(element)
     if element_type is None:
         return False

src/bonsai/bonsai/bim/module/model/railing.py

@@ -138,7 +138,7 @@ def update_bbim_railing_pset(element: ifcopenshell.entity_instance, railing_data
 
 def generate_wall_mounted_handrail_preview(
     obj: bpy.types.Object,
-    props: "BIMRailingProperties",
+    props: "prop.BIMRailingProperties",
     path_data: dict[str, Any],
     si_conversion: float,
 ) -> None:
@@ -860,7 +860,9 @@ class GizmoRailingSchematic(bpy.types.GizmoGroup, gizmo.BaseSchematicGizmoGroup)
         terminal_world = anchor + billboard_rot @ view_rotation @ terminal_local
         self.terminal_gizmo.matrix_basis = gizmo.billboarded_at(terminal_world, billboard_rot, 0.18)
 
-    def update_editing_gizmos(self, context: bpy.types.Context, mw: "Matrix", props: "BIMRailingProperties") -> None:
+    def update_editing_gizmos(
+        self, context: bpy.types.Context, mw: "Matrix", props: "prop.BIMRailingProperties"
+    ) -> None:
         """Hide the pen gizmo while polyline path-edit is active; reposition the cycle icon.
 
         The base class shows the pen gizmo whenever ``is_editing`` is False,

src/bonsai/bonsai/bim/module/project/__init__.py

@@ -18,6 +18,8 @@
 
 import bpy
 
+import bonsai.tool as tool
+
 from . import decorator, gizmo, operator, prop, ui, workspace
 
 classes = (
@@ -58,6 +60,8 @@ classes = (
     operator.LinkIfc,
     operator.LoadBlendMetadataAndIFC,
     operator.LoadLink,
+    operator.AutosavePrompt,
+    operator.LoadAutosavedRecoveryPopup,
     operator.LoadLinkedProject,
     operator.LoadProject,
     operator.LoadProjectElements,
@@ -136,6 +140,7 @@ def register():
 def unregister():
     if not bpy.app.background:
         bpy.utils.unregister_tool(workspace.ExploreTool)
+    tool.Autosave.cancel_timer()
     del bpy.types.Scene.BIMProjectProperties
     del bpy.types.Scene.MeasureToolSettings
     bpy.app.handlers.load_post.remove(decorator.toggle_decorations_on_load)

src/bonsai/bonsai/bim/module/project/operator.py

@@ -985,8 +985,10 @@ class LoadProject(bpy.types.Operator, IFCFileSelector, ImportHelper):
         ),
         default=False,
     )
+    skip_autosave_recovery: bpy.props.BoolProperty(default=False, options={"HIDDEN", "SKIP_SAVE"})
     use_detailed_tooltip: bpy.props.BoolProperty(default=False, options={"HIDDEN"})
     filename_ext = ".ifc"
+    skip_recent: bpy.props.BoolProperty(default=False, options={"HIDDEN", "SKIP_SAVE"})
 
     if TYPE_CHECKING:
         filepath: str
@@ -995,6 +997,7 @@ class LoadProject(bpy.types.Operator, IFCFileSelector, ImportHelper):
         use_relative_path: bool
         should_start_fresh_session: bool
         import_without_ifc_data: bool
+        skip_autosave_recovery: bool
         use_detailed_tooltip: bool
 
     @classmethod
@@ -1041,7 +1044,26 @@ class LoadProject(bpy.types.Operator, IFCFileSelector, ImportHelper):
 
         return tooltip
 
+    def check_autosave_recovery(self, context: bpy.types.Context) -> set["rna_enums.OperatorReturnItems"] | None:
+        if self.skip_autosave_recovery:
+            return None
+        autosaved_filepath = tool.Autosave.get_newer_autosaved_path(self.get_filepath_abs())
+        if not autosaved_filepath:
+            return None
+        return bpy.ops.bim.load_autosaved_recovery_popup(
+            "INVOKE_DEFAULT",
+            original_filepath=str(self.get_filepath_abs()),
+            autosaved_filepath=autosaved_filepath,
+            is_advanced=self.is_advanced,
+            use_relative_path=self.use_relative_path,
+            should_start_fresh_session=self.should_start_fresh_session,
+            import_without_ifc_data=self.import_without_ifc_data,
+        )
+
     def execute(self, context):
+        if recovery := self.check_autosave_recovery(context):
+            return recovery
+
         if (
             tool.Blender.get_addon_preferences().save_metadata_blend_file
             and self.should_start_fresh_session
@@ -1136,7 +1158,8 @@ class LoadProject(bpy.types.Operator, IFCFileSelector, ImportHelper):
             props.should_save_metadata_for_this_file = metadata_doc is not None
 
             tool.Blender.register_toolbar()
-            tool.Project.add_recent_ifc_project(self.get_filepath_abs())
+            if not self.skip_recent:
+                tool.Project.add_recent_ifc_project(self.get_filepath_abs())
 
             if self.is_advanced:
                 pass
@@ -1149,10 +1172,13 @@ class LoadProject(bpy.types.Operator, IFCFileSelector, ImportHelper):
         except:
             bonsai.last_error = traceback.format_exc()
             raise
+        tool.Autosave.reset_timer()
         return {"FINISHED"}
 
     def invoke(self, context, event):
         if self.filepath:
+            if recovery := self.check_autosave_recovery(context):
+                return recovery
             return self.execute(context)
         return ImportHelper.invoke(self, context, event)
 
@@ -1294,6 +1320,11 @@ class LoadProjectElements(bpy.types.Operator):
             if element.IsDecomposedBy:
                 for subelement in element.IsDecomposedBy[0].RelatedObjects:
                     decomposed_elements.add(subelement)
+            # IfcSurfaceFeature (e.g. road markings) adhere to a host element
+            # via IfcRelAdheresToElement, a [1:1] hierarchical relationship in
+            # the same family as aggregation, containment and nesting (IFC4.3).
+            for rel in getattr(element, "HasSurfaceFeatures", ()):
+                decomposed_elements.update(rel.RelatedSurfaceFeatures)
         if decomposed_elements:
             self.append_decomposed_elements(decomposed_elements)
         elements.update(decomposed_elements)
@@ -1942,6 +1973,7 @@ class ExportIFC(bpy.types.Operator, ExportHelper):
     json_compact: bpy.props.BoolProperty(name="Export Compact IFCJSON", default=False)
     should_save_as: bpy.props.BoolProperty(name="Should Save As", default=False, options={"HIDDEN"})
     use_relative_path: bpy.props.BoolProperty(name="Use Relative Path", default=False)
+    skip_recent: bpy.props.BoolProperty(default=False, options={"HIDDEN", "SKIP_SAVE"})
 
     if TYPE_CHECKING:
         filter_glob: str
@@ -2002,6 +2034,18 @@ class ExportIFC(bpy.types.Operator, ExportHelper):
         return {"FINISHED"}
 
     def _execute(self, context):
+        project_props = tool.Project.get_project_props()
+        project_props.use_relative_project_path = self.use_relative_path
+
+        # Fallback if filepath is not set
+        if not getattr(self, "filepath", None) or self.filepath.strip() in ("", ".ifc"):
+            props = tool.Blender.get_bim_props()
+            if props.ifc_file:
+                self.filepath = str(tool.Blender.ensure_blender_path_is_abs(Path(props.ifc_file)))
+            else:
+                self.report({"ERROR"}, "No filepath available for saving.")
+                return {"CANCELLED"}
+
         committed, failed_commits = tool.Parametric.commit_pending_edits()
         # Previews are session-transient — discard rather than commit. Sibling
         # gizmo polls gate on each preview's is_active flag, and a stuck flag
@@ -2064,7 +2108,8 @@ class ExportIFC(bpy.types.Operator, ExportHelper):
         settings.logger.info("Export finished in {:.2f} seconds".format(time.time() - start))
         print("Export finished in {:.2f} seconds".format(time.time() - start))
         # New project created in Bonsai should be in recent projects too.
-        tool.Project.add_recent_ifc_project(Path(output_file))
+        if not self.skip_recent:
+            tool.Project.add_recent_ifc_project(Path(output_file))
         props = tool.Project.get_project_props()
         if props.use_relative_project_path and bpy.data.is_saved:
             output_file = os.path.relpath(output_file, bpy.path.abspath("//"))
@@ -2098,6 +2143,7 @@ class ExportIFC(bpy.types.Operator, ExportHelper):
             )
 
         bonsai.bim.handler.refresh_ui_data()
+        tool.Autosave.reset_timer()
 
     @classmethod
     def description(cls, context, properties):
@@ -2106,6 +2152,97 @@ class ExportIFC(bpy.types.Operator, ExportHelper):
         return "Save the IFC file.  Will save both .IFC/.BLEND files if synced together"
 
 
+class LoadAutosavedRecoveryPopup(bpy.types.Operator):
+    bl_idname = "bim.load_autosaved_recovery_popup"
+    bl_label = "Recover Autosaved File"
+    bl_options = {"REGISTER", "UNDO"}
+
+    original_filepath: bpy.props.StringProperty(options={"SKIP_SAVE"})
+    autosaved_filepath: bpy.props.StringProperty(options={"SKIP_SAVE"})
+    is_advanced: bpy.props.BoolProperty(default=False, options={"SKIP_SAVE"})
+    use_relative_path: bpy.props.BoolProperty(default=False, options={"SKIP_SAVE"})
+    should_start_fresh_session: bpy.props.BoolProperty(default=True, options={"SKIP_SAVE"})
+    import_without_ifc_data: bpy.props.BoolProperty(default=False, options={"SKIP_SAVE"})
+
+    def draw(self, context):
+        layout = self.layout
+        layout.label(text="A newer autosaved copy was found:", icon="INFO")
+        layout.label(text=os.path.basename(self.autosaved_filepath))
+        layout.separator()
+        layout.label(text="Do you want to load the autosaved version instead?")
+        layout.label(text="(Cancel will load the original)")
+
+    def invoke(self, context, event):
+        # invoke_props_dialog is modal - unlike invoke_popup/popup_menu, it
+        # isn't dismissed by the mouse simply leaving its bounds. It always
+        # renders both a fixed "Cancel" button and this confirm_text one, so
+        # the question is framed as Yes/Cancel rather than adding separate
+        # Load buttons on top.
+        return context.window_manager.invoke_props_dialog(
+            self, width=420, title="Recover Autosaved File", confirm_text="Yes"
+        )
+
+    def _load(self, filepath: str, skip_recent: bool) -> set["rna_enums.OperatorReturnItems"]:
+        return bpy.ops.bim.load_project(
+            filepath=filepath,
+            skip_autosave_recovery=True,  # Prevent infinite loop
+            is_advanced=self.is_advanced,
+            use_relative_path=self.use_relative_path,
+            should_start_fresh_session=self.should_start_fresh_session,
+            import_without_ifc_data=self.import_without_ifc_data,
+            skip_recent=skip_recent,
+        )
+
+    def execute(self, context):
+        result = self._load(self.autosaved_filepath, skip_recent=True)
+        # Re-point tracking at the original path so future saves write back
+        # to it, not "_autosaved.ifc".
+        tool.Ifc.set_path(self.original_filepath)
+        return result
+
+    def cancel(self, context):
+        # Also reached via Escape or a click outside the dialog, not just Cancel.
+        self._load(self.original_filepath, skip_recent=False)
+
+
+class AutosavePrompt(bpy.types.Operator):
+    bl_idname = "bim.autosave_prompt"
+    bl_label = "Autosave Reminder"
+    bl_options = set()
+
+    def invoke(self, context, event):
+        return context.window_manager.invoke_props_dialog(
+            self, width=400, confirm_text="Save", title="Autosave Reminder"
+        )
+
+    def draw(self, context):
+        layout = self.layout
+        layout.label(text="The autosave timer has expired.", icon="INFO")
+        layout.label(text="Would you like to save your IFC project now?")
+
+    def execute(self, context):
+        # Get current IFC path
+        props = tool.Blender.get_bim_props()
+        current_ifc_path = props.ifc_file
+
+        if not current_ifc_path:
+            self.report({"WARNING"}, "No IFC file path set. Please save manually.")
+            tool.Autosave.reset_timer()
+            return {"CANCELLED"}
+
+        # Call save_project with explicit filepath using EXEC_DEFAULT
+        result = bpy.ops.bim.save_project(
+            "EXEC_DEFAULT", filepath=current_ifc_path, should_save_as=False, skip_recent=True
+        )
+
+        tool.Autosave.reset_timer()
+        return result
+
+    def cancel(self, context):
+        tool.Autosave.reset_timer()
+        return {"CANCELLED"}
+
+
 class LoadLinkedProject(bpy.types.Operator, ImportHelper):
     bl_idname = "bim.load_linked_project"
     bl_label = "Load Project For Viewing Only"

src/bonsai/bonsai/bim/module/unit/__init__.py

@@ -23,6 +23,8 @@ from . import operator, prop, ui
 classes = (
     operator.AddContextDependentUnit,
     operator.AddConversionBasedUnit,
+    operator.AddDerivedUnit,
+    operator.AddDerivedUnitElement,
     operator.AddMonetaryUnit,
     operator.AddSIUnit,
     operator.AssignSceneUnits,
@@ -32,9 +34,11 @@ classes = (
     operator.EditUnit,
     operator.EnableEditingUnit,
     operator.LoadUnits,
+    operator.RemoveDerivedUnitElement,
     operator.RemoveUnit,
     operator.UnassignUnit,
     prop.Unit,
+    prop.DerivedUnitElement,
     prop.BIMUnitProperties,
     ui.BIM_PT_units,
     ui.BIM_UL_units,

src/bonsai/bonsai/bim/module/unit/data.py

@@ -41,6 +41,8 @@ class UnitsData:
             "unit_classes": cls.unit_classes(),
             "named_unit_types": cls.named_unit_types(),
             "conversion_unit_types": cls.conversion_unit_types(),
+            "derived_unit_types": cls.derived_unit_types(),
+            "named_units": cls.named_units(),
             "total_units": cls.get_total_units(),
         }
         cls.is_loaded = True
@@ -88,6 +90,21 @@ class UnitsData:
     def conversion_unit_types(cls):
         return [(u, u, "") for u in ifcopenshell.util.unit.si_conversions.keys()]
 
+    @classmethod
+    def derived_unit_types(cls):
+        assert (entity := tool.Ifc.schema().declaration_by_name("IfcDerivedUnit").as_entity())
+        values = ifcopenshell.util.attribute.get_enum_items(entity.all_attributes()[1])
+        # USERDEFINED is skipped as it additionally requires a UserDefinedType.
+        return [(c, c, "") for c in sorted(values) if c != "USERDEFINED"]
+
+    @classmethod
+    def named_units(cls):
+        results = []
+        for unit in sorted(tool.Ifc.get().by_type("IfcNamedUnit"), key=lambda u: u.id()):
+            name = ifcopenshell.util.unit.get_full_unit_name(unit)
+            results.append((str(unit.id()), f"{name} ({unit.UnitType})", ""))
+        return results
+
     @classmethod
     def get_total_units(cls):
         ifc = tool.Ifc.get()

src/bonsai/bonsai/bim/module/unit/operator.py

@@ -132,6 +132,56 @@ class AddContextDependentUnit(bpy.types.Operator, tool.Ifc.Operator):
         core.add_context_dependent_unit(tool.Ifc, tool.Unit, unit_type=self.unit_type, name=self.name)
 
 
+class AddDerivedUnitElement(bpy.types.Operator):
+    bl_idname = "bim.add_derived_unit_element"
+    bl_label = "Add Derived Unit Element"
+    bl_options = {"REGISTER", "UNDO"}
+    bl_description = "Add a new named unit and exponent to the derived unit definition"
+
+    def execute(self, context) -> set["rna_enums.OperatorReturnItems"]:
+        props = tool.Unit.get_unit_props()
+        props.derived_unit_elements.add()
+        return {"FINISHED"}
+
+
+class RemoveDerivedUnitElement(bpy.types.Operator):
+    bl_idname = "bim.remove_derived_unit_element"
+    bl_label = "Remove Derived Unit Element"
+    bl_options = {"REGISTER", "UNDO"}
+    bl_description = "Remove this named unit and exponent from the derived unit definition"
+    index: bpy.props.IntProperty()
+
+    def execute(self, context) -> set["rna_enums.OperatorReturnItems"]:
+        props = tool.Unit.get_unit_props()
+        props.derived_unit_elements.remove(self.index)
+        return {"FINISHED"}
+
+
+class AddDerivedUnit(bpy.types.Operator, tool.Ifc.Operator):
+    bl_idname = "bim.add_derived_unit"
+    bl_label = "Add Derived Unit"
+    bl_options = {"REGISTER", "UNDO"}
+    bl_description = "Add a derived unit built from the defined named units and exponents"
+
+    def _execute(self, context):
+        props = tool.Unit.get_unit_props()
+        elements = {}
+        for element in props.derived_unit_elements:
+            if not element.unit:
+                self.report({"ERROR"}, "No named unit selected. Add a named unit (e.g. an SI unit) first.")
+                return {"CANCELLED"}
+            unit = tool.Ifc.get().by_id(int(element.unit))
+            if unit in elements:
+                self.report({"ERROR"}, f"Unit '{unit.Name}' is used in more than one element.")
+                return {"CANCELLED"}
+            elements[unit] = element.exponent
+        if not elements:
+            self.report({"ERROR"}, "A derived unit requires at least one element. Click 'Add Element' first.")
+            return {"CANCELLED"}
+        core.add_derived_unit(tool.Ifc, tool.Unit, unit_type=props.derived_unit_types, elements=elements)
+        props.derived_unit_elements.clear()
+
+
 class EnableEditingUnit(bpy.types.Operator):
     bl_idname = "bim.enable_editing_unit"
     bl_label = "Enable Editing Unit"

src/bonsai/bonsai/bim/module/unit/prop.py

@@ -50,6 +50,27 @@ def get_named_unit_types(self: "BIMUnitProperties", context: bpy.types.Context)
     return UnitsData.data["named_unit_types"]
 
 
+def get_derived_unit_types(self: "BIMUnitProperties", context: bpy.types.Context) -> list[tuple[str, str, str]]:
+    if not UnitsData.is_loaded:
+        UnitsData.load()
+    return UnitsData.data["derived_unit_types"]
+
+
+def get_named_units(self: "DerivedUnitElement", context: bpy.types.Context) -> list[tuple[str, str, str]]:
+    if not UnitsData.is_loaded:
+        UnitsData.load()
+    return UnitsData.data["named_units"]
+
+
+class DerivedUnitElement(PropertyGroup):
+    unit: EnumProperty(items=get_named_units, name="Unit")
+    exponent: IntProperty(name="Exponent", default=1)
+
+    if TYPE_CHECKING:
+        unit: str
+        exponent: int
+
+
 class Unit(PropertyGroup):
     unit_type: StringProperty(name="Unit Type")
     is_assigned: BoolProperty(name="Is Assigned")
@@ -71,6 +92,8 @@ class BIMUnitProperties(PropertyGroup):
     unit_classes: EnumProperty(items=get_unit_classes, name="Unit Classes")
     conversion_unit_types: EnumProperty(items=get_conversion_unit_types, name="Conversion Unit Types")
     named_unit_types: EnumProperty(items=get_named_unit_types, name="Named Unit Types")
+    derived_unit_types: EnumProperty(items=get_derived_unit_types, name="Derived Unit Types")
+    derived_unit_elements: CollectionProperty(name="Derived Unit Elements", type=DerivedUnitElement)
     unit_attributes: CollectionProperty(name="Unit Attributes", type=Attribute)
 
     if TYPE_CHECKING:
@@ -81,4 +104,6 @@ class BIMUnitProperties(PropertyGroup):
         unit_classes: str
         conversion_unit_types: str
         named_unit_types: str
+        derived_unit_types: str
+        derived_unit_elements: bpy.types.bpy_prop_collection_idprop[DerivedUnitElement]
         unit_attributes: bpy.types.bpy_prop_collection_idprop[Attribute]

src/bonsai/bonsai/bim/module/unit/ui.py

@@ -85,7 +85,16 @@ class BIM_PT_units(Panel):
             op = row.operator("bim.add_conversion_based_unit", text="", icon="ADD")
             op.name = self.props.conversion_unit_types
         elif self.props.unit_classes == "IfcDerivedUnit":
-            pass  # TODO
+            prop_with_search(row, self.props, "derived_unit_types", text="")
+            row.operator("bim.add_derived_unit", text="", icon="ADD")
+            box = self.layout.box()
+            for i, element in enumerate(self.props.derived_unit_elements):
+                row = box.row(align=True)
+                prop_with_search(row, element, "unit", text="")
+                row.prop(element, "exponent", text="")
+                row.operator("bim.remove_derived_unit_element", text="", icon="X").index = i
+            row = box.row()
+            row.operator("bim.add_derived_unit_element", text="Add Element", icon="ADD")
         elif self.props.unit_classes == "IfcSIUnit":
             prop_with_search(row, self.props, "named_unit_types", text="")
             op = row.operator("bim.add_si_unit", text="", icon="ADD")

src/bonsai/bonsai/bim/ui.py

@@ -577,6 +577,43 @@ class BIM_ADDON_preferences(bpy.types.AddonPreferences):
     should_disable_undo_on_save: BoolProperty(
         name="Disable Undo When Saving (Faster saves, no undo for you!)", default=False
     )
+
+    def update_autosave_settings(self, context: bpy.types.Context) -> None:
+        if self.autosave_enabled:
+            tool.Autosave.reset_timer()
+        else:
+            tool.Autosave.cancel_timer()
+
+    autosave_enabled: BoolProperty(
+        name="Enable IFC Autosave Timer",
+        description="Periodically remind you to save or automatically create a backup copy of the IFC file",
+        default=False,
+        update=update_autosave_settings,
+    )
+    autosave_interval_minutes: bpy.props.IntProperty(
+        name="Autosave Interval (Minutes)",
+        description="Time between autosave reminders or backups. The timer resets whenever you open or save a project",
+        default=10,
+        min=1,
+        max=1440,
+        update=update_autosave_settings,
+    )
+    autosave_mode: bpy.props.EnumProperty(
+        name="Autosave Mode",
+        items=[
+            (
+                "PROMPT",
+                "Prompt to Save",
+                "Show a dialog offering to save the IFC project when the timer expires",
+            ),
+            (
+                "BACKUP",
+                "Automatic Backup",
+                "Save a backup copy as filename_autosaved.ifc when the timer expires",
+            ),
+        ],
+        default="PROMPT",
+    )
     should_stream: BoolProperty(name="Stream Data From IFC-SPF (Only for advanced users)", default=False)
     should_always_cache: BoolProperty(
         name="Always Cache Geometry",
@@ -689,6 +726,9 @@ class BIM_ADDON_preferences(bpy.types.AddonPreferences):
         bsdd_load_test_dictionaries: bool
         bsdd_baseurl: str
         should_disable_undo_on_save: bool
+        autosave_enabled: bool
+        autosave_interval_minutes: int
+        autosave_mode: Literal["PROMPT", "BACKUP"]
         should_stream: bool
         should_always_cache: bool
         occurrence_name_style: Literal["CLASS", "TYPE", "CUSTOM"]
@@ -837,6 +877,12 @@ class BIM_ADDON_preferences(bpy.types.AddonPreferences):
     def draw_other_settings(self, layout: bpy.types.UILayout, context: bpy.types.Context) -> None:
         layout.prop(self, "opening_focus_opacity")
         layout.prop(self, "should_disable_undo_on_save")
+        layout.separator()
+        layout.label(text="Autosave:")
+        layout.prop(self, "autosave_enabled")
+        if self.autosave_enabled:
+            layout.prop(self, "autosave_interval_minutes")
+            layout.prop(self, "autosave_mode")
         layout.prop(self, "should_stream")
         layout.prop(self, "should_always_cache")
         layout.label(text="bSDD:")

src/bonsai/bonsai/core/drawing.py

@@ -302,9 +302,25 @@ def add_drawing(
         context=drawing.get_body_context(),
         ifc_representation_class=None,
     )
+
+    drawings_parent_group = None
+    for group in ifc.get().by_type("IfcGroup"):
+        if group.Name == "DRAWINGS" and group.ObjectType == "DRAWINGS":
+            drawings_parent_group = group
+            break
+
+    if not drawings_parent_group:
+        drawings_parent_group = ifc.run("group.add_group")
+        ifc.run(
+            "group.edit_group", group=drawings_parent_group, attributes={"Name": "DRAWINGS", "ObjectType": "DRAWINGS"}
+        )
+
     group = ifc.run("group.add_group")
     ifc.run("group.edit_group", group=group, attributes={"Name": drawing_name, "ObjectType": "DRAWING"})
     ifc.run("group.assign_group", group=group, products=[element])
+
+    ifc.run("group.assign_group", group=drawings_parent_group, products=[group])
+
     collector.assign(camera)
     pset = ifc.run("pset.add_pset", product=element, name="EPset_Drawing")
     if drawing.get_unit_system() == "METRIC":
@@ -335,7 +351,22 @@ def add_drawing(
         },
     )
     drawing.setup_shading_styles_path(shading_styles_path)
-    information = ifc.run("document.add_information")
+
+    drawings_parent_document = None
+    for document in ifc.get().by_type("IfcDocumentInformation"):
+        if document.Name == "DRAWINGS" and document.Scope == "DRAWINGS":
+            drawings_parent_document = document
+            break
+
+    if not drawings_parent_document:
+        drawings_parent_document = ifc.run("document.add_information")
+        if ifc.get_schema() == "IFC2X3":
+            attributes = {"DocumentId": "DRAWINGS", "Name": "DRAWINGS", "Scope": "DRAWINGS"}
+        else:
+            attributes = {"Identification": "DRAWINGS", "Name": "DRAWINGS", "Scope": "DRAWINGS"}
+        ifc.run("document.edit_information", information=drawings_parent_document, attributes=attributes)
+
+    information = ifc.run("document.add_information", parent=drawings_parent_document)
     uri = drawing.get_default_drawing_path(drawing_name)
     reference = ifc.run("document.add_reference", information=information)
     if ifc.get_schema() == "IFC2X3":
@@ -363,9 +394,23 @@ def duplicate_drawing(
     drawing_tool.set_name(new_drawing, drawing_name)
     group = drawing_tool.get_drawing_group(new_drawing)
     ifc.run("group.unassign_group", group=group, products=[new_drawing])
+
+    drawings_parent_group = None
+    for parent_group in ifc.get().by_type("IfcGroup"):
+        if parent_group.Name == "DRAWINGS" and parent_group.ObjectType == "DRAWINGS":
+            drawings_parent_group = parent_group
+            break
+
+    if not drawings_parent_group:
+        drawings_parent_group = ifc.run("group.add_group")
+        ifc.run(
+            "group.edit_group", group=drawings_parent_group, attributes={"Name": "DRAWINGS", "ObjectType": "DRAWINGS"}
+        )
+
     new_group = ifc.run("group.add_group")
     ifc.run("group.edit_group", group=new_group, attributes={"Name": drawing_name, "ObjectType": "DRAWING"})
     ifc.run("group.assign_group", group=new_group, products=[new_drawing])
+    ifc.run("group.assign_group", group=drawings_parent_group, products=[new_group])
     if should_duplicate_annotations:
         new_annotations: list[ifcopenshell.entity_instance] = []
         annotation_objs = [ifc.get_object(a) for a in drawing_tool.get_group_elements(group) if a != drawing]
@@ -381,7 +426,21 @@ def duplicate_drawing(
     old_reference = drawing_tool.get_drawing_document(new_drawing)
     ifc.run("document.unassign_document", products=[new_drawing], document=old_reference)
 
-    information = ifc.run("document.add_information")
+    drawings_parent_document = None
+    for document in ifc.get().by_type("IfcDocumentInformation"):
+        if document.Name == "DRAWINGS" and document.Scope == "DRAWINGS":
+            drawings_parent_document = document
+            break
+
+    if not drawings_parent_document:
+        drawings_parent_document = ifc.run("document.add_information")
+        if ifc.get_schema() == "IFC2X3":
+            attributes = {"DocumentId": "DRAWINGS", "Name": "DRAWINGS", "Scope": "DRAWINGS"}
+        else:
+            attributes = {"Identification": "DRAWINGS", "Name": "DRAWINGS", "Scope": "DRAWINGS"}
+        ifc.run("document.edit_information", information=drawings_parent_document, attributes=attributes)
+
+    information = ifc.run("document.add_information", parent=drawings_parent_document)
     uri = drawing_tool.get_default_drawing_path(drawing_name)
     reference = ifc.run("document.add_reference", information=information)
     if ifc.get_schema() == "IFC2X3":

src/bonsai/bonsai/core/product.py

@@ -50,14 +50,15 @@ def copy_z_rotation_to_selected(
     flip: bool = False,
 ) -> int:
     """Apply ``active``'s Z-Euler rotation to each target."""
-    source_z = surveyor.get_z_rotation(active)
+    source_z = surveyor.get_z_rotation(active)  # ty: ignore[missing-argument]
     if flip:
         source_z += math.pi
     rotated = 0
     for obj in targets:
-        if abs(_z_rotation_diff(surveyor.get_z_rotation(obj), source_z)) < Z_ROTATION_ALIGNMENT_TOLERANCE:
+        target_z = surveyor.get_z_rotation(obj)  # ty: ignore[missing-argument]
+        if abs(_z_rotation_diff(target_z, source_z)) < Z_ROTATION_ALIGNMENT_TOLERANCE:
             continue
-        surveyor.set_z_rotation(obj, source_z)
+        surveyor.set_z_rotation(obj, source_z)  # ty: ignore[missing-argument]
         rotated += 1
         if ifc.get_entity(obj) is not None:
             bonsai.core.geometry.edit_object_placement(ifc, geometry, surveyor, obj=obj)

src/bonsai/bonsai/core/tool.py

@@ -804,7 +804,7 @@ class Profile:
 
 @interface
 class Parametric:
-    def get_geom_generation(cls) -> int: pass
+    def get_geom_generation(cls): pass
     def refresh_post_commit(cls, operator) -> None: pass
 
 

src/bonsai/bonsai/core/unit.py

@@ -91,6 +91,17 @@ def add_conversion_based_unit(ifc: type[tool.Ifc], unit: type[tool.Unit], name:
     return result
 
 
+def add_derived_unit(
+    ifc: type[tool.Ifc],
+    unit: type[tool.Unit],
+    unit_type: str,
+    elements: dict[ifcopenshell.entity_instance, int],
+) -> ifcopenshell.entity_instance:
+    result = ifc.run("unit.add_derived_unit", unit_type=unit_type, userdefinedtype=None, attributes=elements)
+    unit.import_units()
+    return result
+
+
 def enable_editing_unit(unit_tool: type[tool.Unit], unit: ifcopenshell.entity_instance) -> None:
     unit_tool.set_active_unit(unit)
     unit_tool.import_unit_attributes(unit)

src/bonsai/bonsai/tool/__init__.py

@@ -80,3 +80,6 @@ from bonsai.tool.type import Type
 from bonsai.tool.unit import Unit
 from bonsai.tool.wall import Wall
 from bonsai.tool.web import Web
+
+# Have to move after import of tool.drawing
+from bonsai.tool.autosave import Autosave  # isort: skip

src/bonsai/bonsai/tool/array.py

@@ -178,6 +178,25 @@ class Array(bonsai.core.tool.Array):
         element_root = cls.get_array_root_guid(element)
         return [o for o in occurrences if cls.get_array_root_guid(o) == element_root]
 
+    @classmethod
+    def select_only_parent(cls, parent_obj: bpy.types.Object, context: bpy.types.Context) -> None:
+        """Post-condition for the user-facing regenerate and finish-edit paths:
+        only ``parent_obj`` is selected + active. Grow and shrink otherwise
+        diverge on which objects stay selected, surfacing an inconsistency."""
+        tool.Blender.select_and_activate_single_object(context, parent_obj)
+
+    @classmethod
+    def is_array_child(cls, element: entity_instance) -> bool:
+        """True when ``element`` is a child of a parametric array — has a
+        BBIM_Array pset whose Parent GUID points to a different element.
+        Lighter than ``get_child_layer_index`` (no ``by_guid`` lookup, no
+        Data parse); suitable for per-element checks in draw handlers."""
+        pset = ifcopenshell.util.element.get_pset(element, "BBIM_Array")
+        if not pset:
+            return False
+        parent_guid = pset.get("Parent")
+        return bool(parent_guid) and parent_guid != element.GlobalId
+
     @classmethod
     def get_child_layer_index(cls, child_element: entity_instance) -> int | None:
         """Index of the layer that produced ``child_element``, or ``None``

src/bonsai/bonsai/tool/autosave.py

@@ -0,0 +1,188 @@
+# Bonsai - OpenBIM Blender Add-on
+# Copyright (C) 2026
+#
+# This file is part of Bonsai.
+#
+# Bonsai is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# Bonsai is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with Bonsai.  If not, see <http://www.gnu.org/licenses/>.
+#
+# This file was generated with the assistance of an AI coding tool.
+
+from __future__ import annotations
+
+import atexit
+import logging
+import os
+from collections.abc import Callable
+from pathlib import Path
+from typing import Union
+
+import bpy
+
+import bonsai.tool as tool
+from bonsai.bim import export_ifc
+from bonsai.bim.module.model import preview_base
+
+AUTOSAVING_SUFFIX = "_autosaving.ifc"
+AUTOSAVED_SUFFIX = "_autosaved.ifc"
+
+_timer_callback: Union[Callable[[], None], None] = None
+# See cleanup_stale_autosave() for why this is a cached plain string rather
+# than looked up live.
+_active_ifc_path_cache: Union[str, None] = None
+
+
+class Autosave:
+    @classmethod
+    def get_paths(cls, ifc_path: Union[str, Path]) -> tuple[Path, Path, Path]:
+        path = Path(ifc_path)
+        stem = path.stem if path.suffix.lower() == ".ifc" else path.name
+        parent = path.parent
+        main_path = path if path.suffix.lower() == ".ifc" else parent / f"{stem}.ifc"
+        autosaving_path = parent / f"{stem}{AUTOSAVING_SUFFIX}"
+        autosaved_path = parent / f"{stem}{AUTOSAVED_SUFFIX}"
+        return main_path, autosaving_path, autosaved_path
+
+    @classmethod
+    def get_active_ifc_path(cls) -> Union[Path, None]:
+        props = tool.Blender.get_bim_props()
+        if not props.ifc_file:
+            return None
+        path = tool.Blender.ensure_blender_path_is_abs(Path(props.ifc_file))
+        if path.suffix.lower() != ".ifc":
+            return None
+        return path
+
+    @classmethod
+    def _update_active_ifc_path_cache(cls) -> None:
+        global _active_ifc_path_cache
+        ifc_path = cls.get_active_ifc_path()
+        _active_ifc_path_cache = ifc_path.as_posix() if ifc_path is not None else None
+
+    @classmethod
+    def is_enabled(cls) -> bool:
+        return bool(tool.Blender.get_addon_preferences().autosave_enabled)
+
+    @classmethod
+    def get_interval_seconds(cls) -> float:
+        minutes = tool.Blender.get_addon_preferences().autosave_interval_minutes
+        return max(1.0, float(minutes) * 60.0)
+
+    @classmethod
+    def is_eligible(cls) -> bool:
+        return cls.is_enabled() and tool.Ifc.get() is not None and cls.get_active_ifc_path() is not None
+
+    @classmethod
+    def cancel_timer(cls) -> None:
+        global _timer_callback
+        if _timer_callback is not None and bpy.app.timers.is_registered(_timer_callback):
+            bpy.app.timers.unregister(_timer_callback)
+        _timer_callback = None
+
+    @classmethod
+    def reset_timer(cls) -> None:
+        cls.cancel_timer()
+        cls._update_active_ifc_path_cache()
+        if not cls.is_eligible():
+            return
+
+        def on_timer() -> None:
+            cls._on_timer_expired()
+            return None
+
+        global _timer_callback
+        _timer_callback = on_timer
+        bpy.app.timers.register(on_timer, first_interval=cls.get_interval_seconds())
+
+    @classmethod
+    def _on_timer_expired(cls) -> None:
+        if not cls.is_eligible():
+            return
+
+        prefs = tool.Blender.get_addon_preferences()
+        bim_props = tool.Blender.get_bim_props()
+
+        if bim_props.is_dirty:
+            if prefs.autosave_mode == "PROMPT":
+                bpy.ops.bim.autosave_prompt("INVOKE_DEFAULT")
+            elif prefs.autosave_mode == "BACKUP":
+                try:
+                    cls.perform_backup(bpy.context)
+                except Exception as error:
+                    print(f"Bonsai: autosave backup failed: {error}")
+        cls.reset_timer()
+
+    @classmethod
+    def perform_backup(cls, context: bpy.types.Context) -> None:
+        ifc_path = cls.get_active_ifc_path()
+        if ifc_path is None:
+            return
+
+        _, autosaving_path, autosaved_path = cls.get_paths(ifc_path)
+        autosaving_path.parent.mkdir(parents=True, exist_ok=True)
+
+        tool.Parametric.commit_pending_edits()
+        preview_base.discard_pending_previews(context.scene)
+
+        logger = logging.getLogger("ExportIFC")
+        output_file = autosaving_path.as_posix().replace("\\", "/")
+        settings = export_ifc.IfcExportSettings.factory(context, output_file, logger)
+        export_ifc.IfcExporter(settings).export()
+
+        try:
+            os.replace(autosaving_path, autosaved_path)
+        except OSError:
+            if autosaving_path.is_file():
+                autosaving_path.unlink(missing_ok=True)
+            raise
+
+    @classmethod
+    def get_newer_autosaved_path(cls, ifc_path: Union[str, Path]) -> Union[str, None]:
+        path = Path(ifc_path)
+        if path.suffix.lower() != ".ifc" or not path.is_file():
+            return None
+
+        _, _, autosaved_path = cls.get_paths(path)
+        if not autosaved_path.is_file():
+            return None
+        if autosaved_path.stat().st_mtime > path.stat().st_mtime:
+            return autosaved_path.as_posix().replace("\\", "/")
+        return None
+
+    @classmethod
+    def cleanup_stale_autosave(cls) -> None:
+        """Remove the active IFC's autosave file(s) on a graceful shutdown.
+
+        Registered via `atexit`, which only runs on a normal interpreter
+        shutdown - never on an actual crash. So a deliberate quit (whether
+        the user saved or chose "don't save") clears the recovery file and
+        won't prompt on next startup, while a genuine crash leaves it in
+        place for recovery, since no atexit callbacks fire then.
+
+        Deliberately reads only `_active_ifc_path_cache` - a plain string
+        kept up to date by `reset_timer()` - rather than touching `bpy` here.
+        By the time `atexit` fires, Blender's own C++ side is torn down far
+        enough that even reading `bpy.context.scene` aborts the process
+        (std::bad_optional_access) instead of raising a catchable exception.
+        """
+        if _active_ifc_path_cache is None:
+            return
+        try:
+            _, autosaving_path, autosaved_path = cls.get_paths(_active_ifc_path_cache)
+            autosaving_path.unlink(missing_ok=True)
+            autosaved_path.unlink(missing_ok=True)
+        except Exception:
+            pass
+
+
+atexit.register(Autosave.cleanup_stale_autosave)

src/bonsai/bonsai/tool/duplicate.py

@@ -248,32 +248,30 @@ class Duplicate(bonsai.core.tool.Duplicate):
         old_to_new: dict[ifcopenshell.entity_instance, list[ifcopenshell.entity_instance]],
     ) -> None:
         for element, data in relationship.items():
-            try:
-                new_relating_element = old_to_new.get(data.relating_element)[0]
-                new_related_element = old_to_new.get(data.related_element)[0]
-            except (KeyError, IndexError, TypeError):
-                continue
-            new_rel = tool.Ifc.run(
-                "geometry.connect_path",
-                relating_element=new_relating_element,
-                related_element=new_related_element,
-                relating_connection=data.relating_connection_type,
-                related_connection=data.related_connection_type,
-            )
+            new_relating_elements = old_to_new.get(data.relating_element) or []
+            new_related_elements = old_to_new.get(data.related_element) or []
             # connect_path hardcodes priorities to []; restore them post-hoc.
             priority_attrs: dict[str, Any] = {}
             if data.relating_priorities:
                 priority_attrs["RelatingPriorities"] = data.relating_priorities
             if data.related_priorities:
                 priority_attrs["RelatedPriorities"] = data.related_priorities
-            if new_rel is not None and priority_attrs:
-                try:
-                    tool.Ifc.run("attribute.edit_attributes", product=new_rel, attributes=priority_attrs)
-                except (RuntimeError, ifcopenshell.Error) as e:
-                    cls._emit_warning(
-                        f"connection priority restore failed for {new_rel}; "
-                        f"duplicate has empty RelatingPriorities/RelatedPriorities: {e}"
-                    )
+            for new_relating_element, new_related_element in zip(new_relating_elements, new_related_elements):
+                new_rel = tool.Ifc.run(
+                    "geometry.connect_path",
+                    relating_element=new_relating_element,
+                    related_element=new_related_element,
+                    relating_connection=data.relating_connection_type,
+                    related_connection=data.related_connection_type,
+                )
+                if new_rel is not None and priority_attrs:
+                    try:
+                        tool.Ifc.run("attribute.edit_attributes", product=new_rel, attributes=priority_attrs)
+                    except (RuntimeError, ifcopenshell.Error) as e:
+                        cls._emit_warning(
+                            f"connection priority restore failed for {new_rel}; "
+                            f"duplicate has empty RelatingPriorities/RelatedPriorities: {e}"
+                        )
 
     @classmethod
     def recreate_port_connections(
@@ -283,46 +281,43 @@ class Duplicate(bonsai.core.tool.Duplicate):
     ) -> None:
         """Recreate ``IfcRelConnectsPorts`` between duplicates; skip records whose duplicate's port count diverges from the snapshot."""
         for relating_element, records in snapshot.by_element.items():
+            new_relatings = old_to_new.get(relating_element) or []
+            expected_relating = snapshot.port_counts.get(relating_element)
             for record in records:
                 related_element = record.related_element
-                try:
-                    new_relating = old_to_new[relating_element][0]
-                    new_related = old_to_new[related_element][0]
-                except (KeyError, IndexError):
-                    continue
-
-                new_relating_ports = tool.System.get_ports(new_relating)
-                new_related_ports = tool.System.get_ports(new_related)
-
-                expected_relating = snapshot.port_counts.get(relating_element)
-                if expected_relating is not None and len(new_relating_ports) != expected_relating:
-                    cls._emit_warning(
-                        f"port reconnect skipped — duplicate has {len(new_relating_ports)} ports, "
-                        f"snapshot had {expected_relating}"
-                    )
-                    continue
+                new_relateds = old_to_new.get(related_element) or []
                 expected_related = snapshot.port_counts.get(related_element)
-                if expected_related is not None and len(new_related_ports) != expected_related:
-                    cls._emit_warning(
-                        f"port reconnect skipped — duplicate has {len(new_related_ports)} ports, "
-                        f"snapshot had {expected_related}"
-                    )
-                    continue
+                for new_relating, new_related in zip(new_relatings, new_relateds):
+                    new_relating_ports = tool.System.get_ports(new_relating)
+                    new_related_ports = tool.System.get_ports(new_related)
 
-                try:
-                    new_port_a = new_relating_ports[record.relating_port_index]
-                    new_port_b = new_related_ports[record.related_port_index]
-                except IndexError:
-                    cls._emit_warning(
-                        f"port reconnect skipped — record references port index past the duplicate's port list"
-                    )
-                    continue
-                try:
-                    tool.Ifc.run(
-                        "system.connect_port",
-                        port1=new_port_a,
-                        port2=new_port_b,
-                        direction=record.direction or "NOTDEFINED",
-                    )
-                except (RuntimeError, ifcopenshell.Error) as e:
-                    cls._emit_warning(f"port reconnect failed between duplicates: {e}")
+                    if expected_relating is not None and len(new_relating_ports) != expected_relating:
+                        cls._emit_warning(
+                            f"port reconnect skipped — duplicate has {len(new_relating_ports)} ports, "
+                            f"snapshot had {expected_relating}"
+                        )
+                        continue
+                    if expected_related is not None and len(new_related_ports) != expected_related:
+                        cls._emit_warning(
+                            f"port reconnect skipped — duplicate has {len(new_related_ports)} ports, "
+                            f"snapshot had {expected_related}"
+                        )
+                        continue
+
+                    try:
+                        new_port_a = new_relating_ports[record.relating_port_index]
+                        new_port_b = new_related_ports[record.related_port_index]
+                    except IndexError:
+                        cls._emit_warning(
+                            f"port reconnect skipped — record references port index past the duplicate's port list"
+                        )
+                        continue
+                    try:
+                        tool.Ifc.run(
+                            "system.connect_port",
+                            port1=new_port_a,
+                            port2=new_port_b,
+                            direction=record.direction or "NOTDEFINED",
+                        )
+                    except (RuntimeError, ifcopenshell.Error) as e:
+                        cls._emit_warning(f"port reconnect failed between duplicates: {e}")

src/bonsai/bonsai/tool/geometry.py

@@ -163,13 +163,21 @@ class Geometry(bonsai.core.tool.Geometry):
                 cls._host_update_queue = {}
                 cls._host_recut_queue = {}
                 for voided_obj in update_queue.values():
-                    if not voided_obj or not voided_obj.data:
+                    try:
+                        if not voided_obj or not voided_obj.data:
+                            continue
+                    except ReferenceError:
+                        # Blender object was deleted while the batch was open
+                        # (e.g. user removed it via the outliner mid-op).
                         continue
                     if tool.Ifc.get_entity(voided_obj) is None:
                         continue
                     bpy.ops.bim.update_representation(obj=voided_obj.name)
                 for voided_obj, _ in recut_queue.values():
-                    if not voided_obj or not voided_obj.data:
+                    try:
+                        if not voided_obj or not voided_obj.data:
+                            continue
+                    except ReferenceError:
                         continue
                     if tool.Ifc.get_entity(voided_obj) is None:
                         continue
@@ -2481,99 +2489,16 @@ class Geometry(bonsai.core.tool.Geometry):
         old_obj_name_to_new_obj_name: dict[str, str] = {}
 
         for obj in objects_to_duplicate:
-            element = tool.Ifc.get_entity(obj)
-            if element:
-                if element.is_a("IfcAnnotation") and element.ObjectType == "DRAWING":
-                    tool.Blender.deselect_object(obj)
-                    continue  # For now, don't copy drawings until we stabilise a bit more. It's tricky.
-                elif tool.Geometry.is_locked(element):
-                    tool.Blender.deselect_object(obj)
-                    continue
-            elif tool.Geometry.is_representation_item(obj):
-                cls.duplicate_ifc_item(obj)
-                continue
-
-            tracked_opening_type = tool.Model.get_tracked_opening_type(obj)
-            is_tracked_opening = bool(tracked_opening_type)
-            keep_data_linked = linked and not element and not is_tracked_opening
-
-            # Prior to duplicating, sync the object placement to make decomposition recreation more stable.
-            cls.commit_placement_if_moved(obj, apply_scale=False)
-
-            new_obj = obj.copy()
-            temp_data = None
-
-            # Currently for optimization we do not apply pending changes (scale or changed .data)
-            # to the original and duplicated objects.
-            # Keep new object edited if original is.
-            if tool.Ifc.is_edited(obj, ignore_scale=True):
-                tool.Ifc.edit(new_obj)
-
-            if obj.data and not keep_data_linked:
-                # assure root.copy_class won't replace the previous mesh globally
-                temp_data = obj.data.copy()
-                new_obj.data = temp_data
-
-                # Unlink from previous boolean element
-                # and keep object tracked for decorations.
-                if is_tracked_opening:
-                    mprops = tool.Geometry.get_mesh_props(new_obj.data)
-                    mprops.ifc_boolean_id = 0
-                    tool.Root.add_tracked_opening(new_obj, tracked_opening_type)
-
-            if obj == active_object:
-                new_active_obj = new_obj
-            for collection in obj.users_collection:
-                collection.objects.link(new_obj)
-            obj.select_set(False)
-            new_obj.select_set(True)
-            old_obj_name_to_new_obj_name[obj.name] = new_obj.name
-
-            if not element:
-                continue
-
-            # clear object's collection so it will be able to have it's own
-            tool.Blender.get_object_bim_props(new_obj).collection = None
-            # copy the actual class
-            new = bonsai.core.root.copy_class(tool.Ifc, tool.Collector, tool.Geometry, tool.Root, obj=new_obj)
-
-            # clean up the orphaned mesh with ifc id of the original object to avoid confusion
-            # IfcGridAxis keeps the same mesh data (it's pointing to ifc id 0, so it's not a problem)
-            if new and temp_data and not new.is_a("IfcGridAxis"):
-                if new.is_a("IfcRelSpaceBoundary"):
-                    surface = new.ConnectionGeometry.SurfaceOnRelatingElement
-                    temp_data.name = f"0/{surface.id()}"
-                    tool.Ifc.link(surface, temp_data)
-                else:
-                    tool.Blender.remove_data_block(temp_data)
-
-            if new:
-                # TODO: handle array data for other cases of duplication
-                array_data = arrays_to_duplicate.get(obj, None)
-                tool.Model.handle_array_on_copied_element(new, array_data)
-                if array_data:
-                    for child in tool.Array.get_all_children_objects(new):
-                        child.select_set(True)
-
-                # TODO: add new array children to recreate their decomposition too
-                old_to_new[element] = [new]
-                if new.is_a("IfcRelSpaceBoundary"):
-                    tool.Boundary.decorate_boundary(new_obj)
-                # Slab-trim booleans (from extend_walls_to_underside) belong to
-                # the source wall's connection, not the copy. Strip them so the
-                # duplicate reverts to its pre-clip extrusion — mirrors the way
-                # filling rels are dropped while manual booleans persist on copy.
-                # Reload the body when something was stripped so the viewport
-                # immediately shows the unclipped geometry; otherwise the user
-                # sees a stale mesh until they Shift+G, which is easy to miss.
-                if new.is_a("IfcWall"):
-                    if tool.Model.strip_underside_booleans(new):
-                        tool.Model.reload_body_representation(new_obj)
-                    # HasOpenings rels don't follow object duplication, so
-                    # the duplicate's body must rebuild to match its current
-                    # opening set.
-                    else:
-                        tool.Model.regenerate_wall(new_obj)
+            new_active = cls._duplicate_ifc_object_once(
+                obj,
+                active_object,
+                linked,
+                arrays_to_duplicate,
+                old_to_new,
+                old_obj_name_to_new_obj_name,
+            )
+            if new_active is not None:
+                new_active_obj = new_active
 
         # Remap Blender parent relationships for duplicated objects
         for old_obj_name, new_obj_name in old_obj_name_to_new_obj_name.items():
@@ -2601,10 +2526,211 @@ class Geometry(bonsai.core.tool.Geometry):
         # Recreate decompositions
         tool.Duplicate.recreate_decompositions(decomposition_relationships, old_to_new)
         cls.remove_linked_aggregate_data(old_to_new)
+
+        # In-loop regenerate_wall runs before recreate_connections, so any new
+        # walls that just received an IfcRelConnectsPathElements have stale
+        # junction geometry — recalculate them now that their connection graph
+        # is complete.
+        cls._recalculate_walls_with_new_connections(old_to_new)
+
         bonsai.bim.handler.refresh_ui_data()
         tool.Root.reload_grid_decorator()
         return old_to_new, new_active_obj or active_object
 
+    @classmethod
+    def duplicate_ifc_object_n_times(
+        cls, source: bpy.types.Object, count: int
+    ) -> dict[ifcopenshell.entity_instance, list[ifcopenshell.entity_instance]]:
+        """N-way duplicate of a single source.
+
+        Same per-copy semantics as duplicate_ifc_objects (IFC class copy,
+        decomposition + connection recreation, body regen for walls), but
+        bypasses the set() dedupe and the arrays_to_duplicate pre-scan so
+        callers building a fresh array don't pay per-call overhead N times.
+        Returns the same old_to_new dict shape, with the source element
+        mapping to the N new entities."""
+        if count <= 0:
+            return {}
+
+        sources = {source}
+        decomposition_relationships = tool.Duplicate.get_decomposition_relationships(sources)
+        connection_relationships = tool.Duplicate.get_connection_relationships(sources)
+        port_connection_snapshot = tool.Duplicate.get_port_connection_relationships(sources)
+        old_to_new: dict[ifcopenshell.entity_instance, list[ifcopenshell.entity_instance]] = {}
+        old_obj_name_to_new_obj_name: dict[str, str] = {}
+
+        for _ in range(count):
+            cls._duplicate_ifc_object_once(
+                source,
+                None,
+                False,
+                {},
+                old_to_new,
+                old_obj_name_to_new_obj_name,
+                keep_source_selected=True,
+            )
+
+        for old_obj_name, new_obj_name in old_obj_name_to_new_obj_name.items():
+            new_obj = bpy.data.objects.get(new_obj_name)
+            if new_obj and new_obj.parent and new_obj.parent.name in old_obj_name_to_new_obj_name:
+                world_matrix = new_obj.matrix_world.copy()
+                new_parent_name = old_obj_name_to_new_obj_name[new_obj.parent.name]
+                new_parent = bpy.data.objects.get(new_parent_name)
+                if new_parent:
+                    new_obj.parent = new_parent
+                    new_obj.matrix_world = world_matrix
+
+        for old in old_to_new.keys():
+            if old.is_a("IfcElementAssembly"):
+                tool.Root.recreate_aggregate(old_to_new)
+
+        cls.remove_old_connections(old_to_new)
+        tool.Duplicate.recreate_connections(connection_relationships, old_to_new)
+        tool.Duplicate.recreate_port_connections(port_connection_snapshot, old_to_new)
+        tool.Duplicate.recreate_decompositions(decomposition_relationships, old_to_new)
+        cls.remove_linked_aggregate_data(old_to_new)
+        cls._recalculate_walls_with_new_connections(old_to_new)
+        bonsai.bim.handler.refresh_ui_data()
+        tool.Root.reload_grid_decorator()
+        return old_to_new
+
+    @classmethod
+    def _duplicate_ifc_object_once(
+        cls,
+        obj: bpy.types.Object,
+        active_object: Optional[bpy.types.Object],
+        linked: bool,
+        arrays_to_duplicate: dict[bpy.types.Object, Any],
+        old_to_new: dict[ifcopenshell.entity_instance, list[ifcopenshell.entity_instance]],
+        old_obj_name_to_new_obj_name: dict[str, str],
+        keep_source_selected: bool = False,
+    ) -> Optional[bpy.types.Object]:
+        """Per-source body of the duplicate flow. Mutates old_to_new and
+        old_obj_name_to_new_obj_name in place. Returns new_obj when obj is
+        the active_object, else None.
+
+        keep_source_selected: when True, skip the source deselect so batched
+        callers can run N iterations without N×2 select flips and without
+        needing a post-loop restore on the source."""
+        new_active_obj: Optional[bpy.types.Object] = None
+        element = tool.Ifc.get_entity(obj)
+        if element:
+            if element.is_a("IfcAnnotation") and element.ObjectType == "DRAWING":
+                tool.Blender.deselect_object(obj)
+                return None  # For now, don't copy drawings until we stabilise a bit more. It's tricky.
+            elif tool.Geometry.is_locked(element):
+                tool.Blender.deselect_object(obj)
+                return None
+        elif tool.Geometry.is_representation_item(obj):
+            cls.duplicate_ifc_item(obj)
+            return None
+
+        tracked_opening_type = tool.Model.get_tracked_opening_type(obj)
+        is_tracked_opening = bool(tracked_opening_type)
+        keep_data_linked = linked and not element and not is_tracked_opening
+
+        # Prior to duplicating, sync the object placement to make decomposition recreation more stable.
+        cls.commit_placement_if_moved(obj, apply_scale=False)
+
+        new_obj = obj.copy()
+        temp_data = None
+
+        # Currently for optimization we do not apply pending changes (scale or changed .data)
+        # to the original and duplicated objects.
+        # Keep new object edited if original is.
+        if tool.Ifc.is_edited(obj, ignore_scale=True):
+            tool.Ifc.edit(new_obj)
+
+        if obj.data and not keep_data_linked:
+            # assure root.copy_class won't replace the previous mesh globally
+            temp_data = obj.data.copy()
+            new_obj.data = temp_data
+
+            # Unlink from previous boolean element
+            # and keep object tracked for decorations.
+            if is_tracked_opening:
+                mprops = tool.Geometry.get_mesh_props(new_obj.data)
+                mprops.ifc_boolean_id = 0
+                tool.Root.add_tracked_opening(new_obj, tracked_opening_type)
+
+        if obj == active_object:
+            new_active_obj = new_obj
+        for collection in obj.users_collection:
+            collection.objects.link(new_obj)
+        if not keep_source_selected:
+            obj.select_set(False)
+        new_obj.select_set(True)
+        old_obj_name_to_new_obj_name[obj.name] = new_obj.name
+
+        if not element:
+            return new_active_obj
+
+        # clear object's collection so it will be able to have it's own
+        tool.Blender.get_object_bim_props(new_obj).collection = None
+        # copy the actual class
+        new = bonsai.core.root.copy_class(tool.Ifc, tool.Collector, tool.Geometry, tool.Root, obj=new_obj)
+
+        # clean up the orphaned mesh with ifc id of the original object to avoid confusion
+        # IfcGridAxis keeps the same mesh data (it's pointing to ifc id 0, so it's not a problem)
+        if new and temp_data and not new.is_a("IfcGridAxis"):
+            if new.is_a("IfcRelSpaceBoundary"):
+                surface = new.ConnectionGeometry.SurfaceOnRelatingElement
+                temp_data.name = f"0/{surface.id()}"
+                tool.Ifc.link(surface, temp_data)
+            else:
+                tool.Blender.remove_data_block(temp_data)
+
+        if new:
+            # TODO: handle array data for other cases of duplication
+            array_data = arrays_to_duplicate.get(obj, None)
+            tool.Model.handle_array_on_copied_element(new, array_data)
+            if array_data:
+                for child in tool.Array.get_all_children_objects(new):
+                    child.select_set(True)
+
+            # TODO: add new array children to recreate their decomposition too
+            old_to_new.setdefault(element, []).append(new)
+            if new.is_a("IfcRelSpaceBoundary"):
+                tool.Boundary.decorate_boundary(new_obj)
+            # Slab-trim booleans (from extend_walls_to_underside) belong to
+            # the source wall's connection, not the copy. Strip them so the
+            # duplicate reverts to its pre-clip extrusion — mirrors the way
+            # filling rels are dropped while manual booleans persist on copy.
+            # Reload the body when something was stripped so the viewport
+            # immediately shows the unclipped geometry; otherwise the user
+            # sees a stale mesh until they Shift+G, which is easy to miss.
+            if new.is_a("IfcWall"):
+                if tool.Model.strip_underside_booleans(new):
+                    tool.Model.reload_body_representation(new_obj)
+                # HasOpenings rels don't follow object duplication, so
+                # the duplicate's body must rebuild to match its current
+                # opening set.
+                else:
+                    tool.Model.regenerate_wall(new_obj)
+
+        return new_active_obj
+
+    @classmethod
+    def _recalculate_walls_with_new_connections(
+        cls, old_to_new: dict[ifcopenshell.entity_instance, list[ifcopenshell.entity_instance]]
+    ) -> None:
+        """Recalculate new IfcWall duplicates that just received an
+        ``IfcRelConnectsPathElements``. The in-loop ``regenerate_wall`` runs
+        before ``recreate_connections``, so wall body geometry doesn't reflect
+        the junction until this second pass."""
+        walls_to_recalc: list[bpy.types.Object] = []
+        for new_list in old_to_new.values():
+            for new_entity in new_list:
+                if not new_entity.is_a("IfcWall"):
+                    continue
+                if not (getattr(new_entity, "ConnectedTo", None) or getattr(new_entity, "ConnectedFrom", None)):
+                    continue
+                new_obj = tool.Ifc.get_object(new_entity)
+                if new_obj is not None:
+                    walls_to_recalc.append(new_obj)
+        if walls_to_recalc:
+            tool.Model.recalculate_walls(walls_to_recalc)
+
     @classmethod
     def duplicate_ifc_item(cls, obj: bpy.types.Object) -> None:
         props = tool.Geometry.get_geometry_props()

src/bonsai/bonsai/tool/model.py

@@ -59,6 +59,7 @@ from ifcopenshell.util.shape_builder import ShapeBuilder, np_to_3d
 from mathutils import Matrix, Vector
 
 import bonsai.core.geometry
+import bonsai.core.model
 import bonsai.core.tool
 import bonsai.tool as tool
 from bonsai.bim import import_ifc
@@ -1247,6 +1248,35 @@ class Model(bonsai.core.tool.Model):
         with tool.Geometry.batch_host_recut():
             cls._regenerate_array_body(parent_obj, data, array_layers_to_apply)
 
+    @classmethod
+    def _prune_orphan_array_children(cls, array: dict[str, Any]) -> None:
+        """Drop GUIDs from ``array['children']`` whose IFC entity or Blender
+        object is no longer alive, and cascade-remove the orphan IFC entity
+        if it still exists. Outliner / keyboard delete of a Bonsai-managed
+        object bypasses ``bim.delete``'s cascade, leaving dangling opening
+        and filling references that later confuse regen and crash the
+        ``batch_host_recut`` drain."""
+        live_guids: list[str] = []
+        ifc_file = tool.Ifc.get()
+        for guid in array["children"]:
+            try:
+                element = ifc_file.by_guid(guid)
+            except RuntimeError:
+                continue
+            obj = tool.Ifc.get_object(element)
+            try:
+                is_live = obj is not None and obj.data is not None
+            except ReferenceError:
+                is_live = False
+            if is_live:
+                live_guids.append(guid)
+                continue
+            try:
+                ifcopenshell.api.root.remove_product(ifc_file, product=element)
+            except (RuntimeError, ifcopenshell.Error):
+                pass
+        array["children"] = live_guids
+
     @classmethod
     def _regenerate_array_body(
         cls, parent_obj: bpy.types.Object, data: list[dict[str, Any]], array_layers_to_apply: Iterable[int]
@@ -1262,6 +1292,7 @@ class Model(bonsai.core.tool.Model):
         obj_stack = [parent_obj]
 
         for array_i, array in enumerate(data):
+            cls._prune_orphan_array_children(array)
             child_i = 0
             existing_children = set(array["children"])
             total_existing_children = len(array["children"])
@@ -1275,6 +1306,14 @@ class Model(bonsai.core.tool.Model):
             else:
                 base_offset = Vector([array["x"], array["y"], array["z"]]) * unit_scale
 
+            target_new_in_this_layer = (array["count"] - 1) * len(obj_stack)
+            missing_count = max(0, target_new_in_this_layer - total_existing_children)
+            new_entities_pool: list[ifcopenshell.entity_instance] = []
+            if missing_count > 0:
+                batch_old_to_new = tool.Geometry.duplicate_ifc_object_n_times(parent_obj, missing_count)
+                new_entities_pool = batch_old_to_new.get(parent_element, [])
+            new_entities_iter = iter(new_entities_pool)
+
             for i in range(array["count"]):
                 if i == 0:
                     continue
@@ -1292,8 +1331,13 @@ class Model(bonsai.core.tool.Model):
                         child_obj = tool.Ifc.get_object(child_element)
                         assert child_obj
                     except (IndexError, RuntimeError, AssertionError):
-                        old_to_new, _ = tool.Geometry.duplicate_ifc_objects([parent_obj])
-                        child_element = next(iter(old_to_new.values()))[0]
+                        try:
+                            child_element = next(new_entities_iter)
+                        except StopIteration:
+                            # Stale-GUID mid-list left the pool exhausted; fall back
+                            # to a one-off duplicate so the layer can still complete.
+                            old_to_new, _ = tool.Geometry.duplicate_ifc_objects([parent_obj])
+                            child_element = next(iter(old_to_new.values()))[0]
                         child_obj = tool.Ifc.get_object(child_element)
 
                     # add child pset
@@ -1361,14 +1405,7 @@ class Model(bonsai.core.tool.Model):
             tool.Ifc.get(), pset=pset, properties={"Data": json_data, "Parent": parent_element.GlobalId}
         )
 
-        # Post-condition: parent is selected on return. duplicate_ifc_objects
-        # deselects the source on every call inside the regen loop; without
-        # this restore, callers get a deselected parent for arrays with N >= 2.
-        # TODO: batch the per-child duplicate_ifc_objects([parent]) calls into
-        # a single N-way duplicate — N depsgraph churns + N select/deselect
-        # flips is wasteful, and a batched duplicate would also remove the
-        # need for this restore.
-        parent_obj.select_set(True)
+        tool.Blender.set_object_selection(parent_obj, True)
 
     @classmethod
     def mirror_parent_void_fillings_to_children(

src/bonsai/bonsai/tool/root.py

@@ -373,35 +373,37 @@ class Root(bonsai.core.tool.Root):
                 try:
                     new_aggregate = old_to_new[old_aggregate]
                 except:
-                    bonsai.core.aggregate.unassign_object(
-                        tool.Ifc,
-                        tool.Aggregate,
-                        tool.Collector,
-                        relating_obj=tool.Ifc.get_object(old_aggregate),
-                        related_obj=tool.Ifc.get_object(new[0]),
-                    )
-                    continue
-
-                bonsai.core.aggregate.assign_object(
-                    tool.Ifc,
-                    tool.Aggregate,
-                    tool.Collector,
-                    relating_obj=tool.Ifc.get_object(new_aggregate[0]),
-                    related_obj=tool.Ifc.get_object(new[0]),
-                )
-
-                # Make sure that the array children also get reassigned to the correct aggregate
-                pset = ifcopenshell.util.element.get_pset(new[0], "BBIM_Array")
-                if pset:
-                    array_children = tool.Array.get_all_children_objects(new[0])
-                    for obj in array_children:
-                        bonsai.core.aggregate.assign_object(
+                    for new_entity in new:
+                        bonsai.core.aggregate.unassign_object(
                             tool.Ifc,
                             tool.Aggregate,
                             tool.Collector,
-                            relating_obj=tool.Ifc.get_object(new_aggregate[0]),
-                            related_obj=tool.Ifc.get_object(tool.Ifc.get_entity(obj)),
+                            relating_obj=tool.Ifc.get_object(old_aggregate),
+                            related_obj=tool.Ifc.get_object(new_entity),
                         )
+                    continue
+
+                for new_entity in new:
+                    bonsai.core.aggregate.assign_object(
+                        tool.Ifc,
+                        tool.Aggregate,
+                        tool.Collector,
+                        relating_obj=tool.Ifc.get_object(new_aggregate[0]),
+                        related_obj=tool.Ifc.get_object(new_entity),
+                    )
+
+                    # Make sure that the array children also get reassigned to the correct aggregate
+                    pset = ifcopenshell.util.element.get_pset(new_entity, "BBIM_Array")
+                    if pset:
+                        array_children = tool.Array.get_all_children_objects(new_entity)
+                        for obj in array_children:
+                            bonsai.core.aggregate.assign_object(
+                                tool.Ifc,
+                                tool.Aggregate,
+                                tool.Collector,
+                                relating_obj=tool.Ifc.get_object(new_aggregate[0]),
+                                related_obj=tool.Ifc.get_object(tool.Ifc.get_entity(obj)),
+                            )
 
         if new_aggregate is None:
             return

src/bonsai/bonsai/tool/system.py

@@ -357,6 +357,13 @@ class System(bonsai.core.tool.System):
             if not cls.is_mep_element(element):
                 continue
 
+            # Array children inherit port topology from their parent's IFC
+            # entity, but their positions are derived — drawing ports on every
+            # copy of an arrayed segment doubles up markers and misleads the
+            # user into thinking each copy has its own port network.
+            if tool.Array.is_array_child(element):
+                continue
+
             selected_element = element in connected_elements
             verts_pos = []
 

src/bonsai/test/bim/module/model/test_array_batch_recut.py

@@ -35,6 +35,7 @@ from unittest.mock import Mock, patch
 
 import bpy
 import ifcopenshell
+import ifcopenshell.api.pset
 import pytest
 
 import bonsai.tool as tool

src/bonsai/test/bim/module/model/test_array_duplicate_batched.py

@@ -0,0 +1,716 @@
+# Bonsai - OpenBIM Blender Add-on
+# Copyright (C) 2026
+#
+# This file is part of Bonsai.
+#
+# Bonsai is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# Bonsai is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with Bonsai.  If not, see <http://www.gnu.org/licenses/>.
+#
+# This file was generated with the assistance of an AI coding tool.
+
+"""Tests for the batched array-duplicate path.
+
+`tool.Geometry.duplicate_ifc_object_n_times` lifts the per-call overhead of
+`duplicate_ifc_objects` (snapshot, UI refresh, decorator reload, select
+flips) out of the per-child loop in `_regenerate_array_body`. These tests
+pin three contracts:
+
+1. N-way batched duplicate produces N distinct entities mapped from the
+   source under `old_to_new[source_element]`, and the source object stays
+   selected throughout (no per-iteration deselect).
+2. Per-layer batching collapses the N independent UI refreshes into one.
+3. End-to-end array regen still yields the same number and shape of
+   children as the per-call baseline."""
+
+import json
+from unittest.mock import patch
+
+import bpy
+import ifcopenshell
+import ifcopenshell.api.pset
+import ifcopenshell.util.element
+import pytest
+
+import bonsai.tool as tool
+from test.bim.bootstrap import NewFile
+
+pytestmark = pytest.mark.model
+
+
+def _build_actuator(name: str = "Actuator") -> tuple[bpy.types.Object, ifcopenshell.entity_instance]:
+    """Minimal IfcActuator + cube — matches the test_array_batch_recut.py shape."""
+    bpy.ops.bim.create_project()
+    bpy.ops.mesh.primitive_cube_add()
+    obj = bpy.context.active_object
+    obj.name = name
+    rprops = tool.Root.get_root_props()
+    rprops.ifc_product = "IfcElement"
+    bpy.ops.bim.assign_class(ifc_class="IfcActuator", predefined_type="ELECTRICACTUATOR", userdefined_type="")
+    element = tool.Ifc.get_entity(obj)
+    return obj, element
+
+
+def _build_actuator_with_array_pset(
+    count: int, x: float = 1.0
+) -> tuple[bpy.types.Object, ifcopenshell.entity_instance, list[dict]]:
+    obj, element = _build_actuator()
+    parent_data = [
+        {
+            "children": [],
+            "count": count,
+            "method": "OFFSET",
+            "x": x,
+            "y": 0.0,
+            "z": 0.0,
+            "use_local_space": False,
+            "sync_children": False,
+        }
+    ]
+    pset = ifcopenshell.api.pset.add_pset(tool.Ifc.get(), product=element, name="BBIM_Array")
+    ifcopenshell.api.pset.edit_pset(
+        tool.Ifc.get(),
+        pset=pset,
+        properties={"Data": json.dumps(parent_data), "Parent": element.GlobalId},
+    )
+    return obj, element, parent_data
+
+
+class TestDuplicateIfcObjectNTimes(NewFile):
+    def test_returns_empty_dict_for_zero_count(self):
+        obj, _ = _build_actuator()
+        result = tool.Geometry.duplicate_ifc_object_n_times(obj, 0)
+        assert result == {}
+
+    def test_returns_empty_dict_for_negative_count(self):
+        obj, _ = _build_actuator()
+        result = tool.Geometry.duplicate_ifc_object_n_times(obj, -3)
+        assert result == {}
+
+    def test_produces_n_distinct_entities(self):
+        obj, element = _build_actuator()
+        result = tool.Geometry.duplicate_ifc_object_n_times(obj, 5)
+        new_entities = result.get(element)
+        assert new_entities is not None
+        assert len(new_entities) == 5
+        assert len({e.id() for e in new_entities}) == 5
+        for new_entity in new_entities:
+            assert new_entity.is_a("IfcActuator")
+            assert new_entity.GlobalId != element.GlobalId
+
+    def test_source_stays_selected_after_batch(self):
+        obj, _ = _build_actuator()
+        obj.select_set(True)
+        tool.Geometry.duplicate_ifc_object_n_times(obj, 4)
+        assert obj in bpy.context.selected_objects, "source object must remain selected across batched duplicates"
+
+    def test_each_new_entity_has_blender_object(self):
+        obj, element = _build_actuator()
+        result = tool.Geometry.duplicate_ifc_object_n_times(obj, 3)
+        for new_entity in result[element]:
+            new_obj = tool.Ifc.get_object(new_entity)
+            assert new_obj is not None
+            assert new_obj is not obj
+
+
+class TestBatchedRefreshUIDataCallCount(NewFile):
+    def test_n_times_calls_refresh_ui_data_once(self):
+        obj, _ = _build_actuator()
+        with patch("bonsai.bim.handler.refresh_ui_data") as refresh_mock:
+            tool.Geometry.duplicate_ifc_object_n_times(obj, 8)
+        assert (
+            refresh_mock.call_count == 1
+        ), f"batched 8-way duplicate must call refresh_ui_data once, got {refresh_mock.call_count}"
+
+    def test_n_times_calls_reload_grid_decorator_once(self):
+        obj, _ = _build_actuator()
+        with patch.object(tool.Root, "reload_grid_decorator") as reload_mock:
+            tool.Geometry.duplicate_ifc_object_n_times(obj, 8)
+        assert reload_mock.call_count == 1
+
+
+class TestRegenerateArrayEndToEnd(NewFile):
+    def test_regenerate_array_creates_expected_children(self):
+        obj, element, parent_data = _build_actuator_with_array_pset(count=8)
+        bpy.context.view_layer.objects.active = obj
+        tool.Model.regenerate_array(obj, parent_data)
+
+        layer = parent_data[0]
+        assert len(layer["children"]) == 7, "8-element array means 7 new children (parent + 7)"
+        for child_guid in layer["children"]:
+            child_element = tool.Ifc.get().by_guid(child_guid)
+            assert child_element is not None
+            assert child_element.is_a("IfcActuator")
+            child_pset = ifcopenshell.util.element.get_pset(child_element, "BBIM_Array")
+            assert child_pset is not None
+            assert child_pset["Parent"] == element.GlobalId
+
+    def test_regenerate_array_parent_stays_selected(self):
+        obj, element, parent_data = _build_actuator_with_array_pset(count=4)
+        bpy.context.view_layer.objects.active = obj
+        obj.select_set(True)
+        tool.Model.regenerate_array(obj, parent_data)
+        assert (
+            obj in bpy.context.selected_objects
+        ), "regenerate_array must leave parent_obj selected on return (post-condition)"
+
+    def test_regen_operator_leaves_only_parent_selected_and_active(self):
+        """Post-condition parity between grow and shrink for the user-facing
+        ``bim.regenerate_array`` operator: only the parent is selected + active;
+        every child is deselected. Pre-fix the grow path left new children
+        selected, creating inconsistency with the shrink path.
+
+        Scoped to the operator, not the tool method — ``remove_array`` and
+        ``apply_array`` also invoke ``tool.Model.regenerate_array`` internally
+        but expect a different post-selection state (children stay selected
+        for user follow-up work)."""
+        obj, element, parent_data = _build_actuator_with_array_pset(count=6)
+        bpy.context.view_layer.objects.active = obj
+        obj.select_set(True)
+        bpy.ops.bim.regenerate_array()
+
+        assert obj in bpy.context.selected_objects
+        assert bpy.context.view_layer.objects.active is obj
+        parent_pset = ifcopenshell.util.element.get_pset(element, "BBIM_Array")
+        parent_data_after = json.loads(parent_pset["Data"])
+        for child_guid in parent_data_after[0]["children"]:
+            child_element = tool.Ifc.get().by_guid(child_guid)
+            child_obj = tool.Ifc.get_object(child_element)
+            assert (
+                child_obj not in bpy.context.selected_objects
+            ), f"child {child_obj.name} must be deselected on regenerate_array return"
+
+    def test_regen_operator_after_shrink_still_leaves_only_parent_selected(self):
+        obj, element, parent_data = _build_actuator_with_array_pset(count=6)
+        bpy.context.view_layer.objects.active = obj
+        bpy.ops.bim.regenerate_array()
+
+        parent_pset = ifcopenshell.util.element.get_pset(element, "BBIM_Array")
+        arrays = json.loads(parent_pset["Data"])
+        arrays[0]["count"] = 3
+        pset_entity = tool.Ifc.get().by_id(parent_pset["id"])
+        ifcopenshell.api.pset.edit_pset(tool.Ifc.get(), pset=pset_entity, properties={"Data": json.dumps(arrays)})
+        bpy.ops.bim.regenerate_array()
+
+        assert obj in bpy.context.selected_objects
+        assert bpy.context.view_layer.objects.active is obj
+        parent_pset = ifcopenshell.util.element.get_pset(element, "BBIM_Array")
+        arrays_after = json.loads(parent_pset["Data"])
+        for child_guid in arrays_after[0]["children"]:
+            child_element = tool.Ifc.get().by_guid(child_guid)
+            child_obj = tool.Ifc.get_object(child_element)
+            assert child_obj not in bpy.context.selected_objects
+
+    def test_regenerate_array_child_positions_match_offset(self):
+        obj, element, parent_data = _build_actuator_with_array_pset(count=4, x=2.5)
+        bpy.context.view_layer.objects.active = obj
+        parent_x = obj.matrix_world.translation.x
+        tool.Model.regenerate_array(obj, parent_data)
+
+        layer = parent_data[0]
+        for i, child_guid in enumerate(layer["children"], start=1):
+            child_element = tool.Ifc.get().by_guid(child_guid)
+            child_obj = tool.Ifc.get_object(child_element)
+            expected_x = parent_x + 2.5 * i
+            assert child_obj.matrix_world.translation.x == pytest.approx(
+                expected_x
+            ), f"child {i}: expected x≈{expected_x}, got {child_obj.matrix_world.translation.x}"
+
+
+class TestRegenerateArrayUIRefreshCoalesces(NewFile):
+    def test_n_children_grow_calls_refresh_ui_data_once_per_layer(self):
+        obj, element, parent_data = _build_actuator_with_array_pset(count=8)
+        bpy.context.view_layer.objects.active = obj
+        with patch("bonsai.bim.handler.refresh_ui_data") as refresh_mock:
+            tool.Model.regenerate_array(obj, parent_data)
+        assert refresh_mock.call_count == 1, (
+            "growing an array layer from 0 to 7 children must call refresh_ui_data once, "
+            f"got {refresh_mock.call_count}"
+        )
+
+    def test_n_children_grow_calls_reload_grid_decorator_once_per_layer(self):
+        obj, element, parent_data = _build_actuator_with_array_pset(count=8)
+        bpy.context.view_layer.objects.active = obj
+        with patch.object(tool.Root, "reload_grid_decorator") as reload_mock:
+            tool.Model.regenerate_array(obj, parent_data)
+        assert reload_mock.call_count == 1
+
+
+class TestRecreateAggregateIteratesAllNew(NewFile):
+    """Pins the [0]-indexing sweep in tool/root.py recreate_aggregate. When the
+    new-list has N>1 entries (the batched-duplicate shape), every entry must be
+    aggregate-assigned, not just new[0]."""
+
+    def test_iterates_assign_object_per_new_entity_when_old_has_aggregate(self):
+        from unittest.mock import Mock
+
+        old_assembly = Mock()
+        old_assembly.is_a = lambda c: c == "IfcElementAssembly"
+        old_parent_aggregate = Mock()
+        old_parent_aggregate.is_a = lambda c: False
+
+        new_assemblies = [Mock(), Mock(), Mock()]
+        new_parent_aggregate = [Mock()]
+
+        old_to_new = {old_assembly: new_assemblies, old_parent_aggregate: new_parent_aggregate}
+
+        with patch(
+            "ifcopenshell.util.element.get_aggregate",
+            side_effect=lambda e: old_parent_aggregate if e is old_assembly else None,
+        ), patch("bonsai.core.aggregate.assign_object") as assign_mock, patch(
+            "ifcopenshell.util.element.get_pset", return_value=None
+        ), patch.object(
+            tool.Ifc, "get_object", side_effect=lambda e: Mock(spec=bpy.types.Object)
+        ), patch.object(
+            tool.Blender, "select_and_activate_single_object"
+        ):
+            tool.Root.recreate_aggregate(old_to_new)
+
+        assert (
+            assign_mock.call_count == 3
+        ), f"recreate_aggregate must assign each of N new entities (not just new[0]); got {assign_mock.call_count}"
+
+    def test_iterates_unassign_object_per_new_entity_when_aggregate_missing(self):
+        from unittest.mock import Mock
+
+        old_assembly = Mock()
+        old_assembly.is_a = lambda c: c == "IfcElementAssembly"
+        old_parent_aggregate = Mock()
+
+        new_assemblies = [Mock(), Mock(), Mock()]
+        old_to_new = {old_assembly: new_assemblies}  # parent aggregate NOT in old_to_new
+
+        with patch(
+            "ifcopenshell.util.element.get_aggregate",
+            side_effect=lambda e: old_parent_aggregate if e is old_assembly else None,
+        ), patch("bonsai.core.aggregate.unassign_object") as unassign_mock, patch.object(
+            tool.Ifc, "get_object", side_effect=lambda e: Mock(spec=bpy.types.Object)
+        ):
+            tool.Root.recreate_aggregate(old_to_new)
+
+        assert unassign_mock.call_count == 3, (
+            f"recreate_aggregate must unassign each of N new entities when parent aggregate is missing; "
+            f"got {unassign_mock.call_count}"
+        )
+
+
+class TestRecreateConnectionsZipsPairs(NewFile):
+    """Pins the [0]-indexing sweep in tool/duplicate.py recreate_connections. When
+    both sides of a connection are duplicated N times, zip-pair the N new
+    relating with N new related; when only one side is duplicated, skip."""
+
+    def _make_connection_data(self):
+        from unittest.mock import Mock
+
+        from bonsai.tool.duplicate import ConnectionRecord
+
+        return ConnectionRecord(
+            type="path",
+            relating_element=Mock(),
+            related_element=Mock(),
+            relating_connection_type="ATSTART",
+            related_connection_type="ATEND",
+            relating_priorities=[],
+            related_priorities=[],
+        )
+
+    def test_zips_n_pairs_when_both_sides_duplicated(self):
+        from unittest.mock import Mock
+
+        data = self._make_connection_data()
+        old_to_new = {
+            data.relating_element: [Mock(), Mock(), Mock()],
+            data.related_element: [Mock(), Mock(), Mock()],
+        }
+        relationship = {Mock(): data}
+
+        with patch.object(tool.Ifc, "run", return_value=None) as run_mock:
+            tool.Duplicate.recreate_connections(relationship, old_to_new)
+
+        connect_calls = [c for c in run_mock.call_args_list if c.args and c.args[0] == "geometry.connect_path"]
+        assert (
+            len(connect_calls) == 3
+        ), f"zip-pair must create 3 connect_path calls for 3-vs-3 batched duplicate; got {len(connect_calls)}"
+
+    def test_skips_when_other_side_not_duplicated(self):
+        from unittest.mock import Mock
+
+        data = self._make_connection_data()
+        # Only relating side is in old_to_new; related side was NOT duplicated.
+        old_to_new = {data.relating_element: [Mock(), Mock(), Mock()]}
+        relationship = {Mock(): data}
+
+        with patch.object(tool.Ifc, "run", return_value=None) as run_mock:
+            tool.Duplicate.recreate_connections(relationship, old_to_new)
+
+        connect_calls = [c for c in run_mock.call_args_list if c.args and c.args[0] == "geometry.connect_path"]
+        assert (
+            connect_calls == []
+        ), "when only one side of a connection is in old_to_new, no connections should be recreated"
+
+    def test_single_pair_case_unchanged(self):
+        """Pre-sweep behavior (1 source -> 1 new) must still work — zip with two 1-element lists."""
+        from unittest.mock import Mock
+
+        data = self._make_connection_data()
+        old_to_new = {
+            data.relating_element: [Mock()],
+            data.related_element: [Mock()],
+        }
+        relationship = {Mock(): data}
+
+        with patch.object(tool.Ifc, "run", return_value=None) as run_mock:
+            tool.Duplicate.recreate_connections(relationship, old_to_new)
+
+        connect_calls = [c for c in run_mock.call_args_list if c.args and c.args[0] == "geometry.connect_path"]
+        assert len(connect_calls) == 1
+
+
+class TestRecalculateWallsWithNewConnections(NewFile):
+    """Pins the post-connection wall recalc: after ``recreate_connections``
+    wires new IfcRelConnectsPathElements onto duplicated walls, the wall
+    bodies must be re-recalculated because the in-loop ``regenerate_wall``
+    fired before the connections existed. Otherwise the junction geometry
+    stays stale and the user has to manually regen."""
+
+    def test_walls_with_new_connections_are_recalculated(self):
+        from unittest.mock import Mock
+
+        wall_new = Mock()
+        wall_new.is_a = lambda c: c == "IfcWall"
+        wall_new.ConnectedTo = [Mock()]
+        wall_new.ConnectedFrom = []
+
+        wall_obj = Mock(spec=bpy.types.Object)
+        old_to_new = {Mock(): [wall_new]}
+
+        with patch.object(tool.Ifc, "get_object", return_value=wall_obj), patch.object(
+            tool.Model, "recalculate_walls"
+        ) as recalc_mock:
+            tool.Geometry._recalculate_walls_with_new_connections(old_to_new)
+
+        assert recalc_mock.call_count == 1
+        assert recalc_mock.call_args.args[0] == [wall_obj]
+
+    def test_walls_without_connections_are_skipped(self):
+        from unittest.mock import Mock
+
+        wall_new = Mock()
+        wall_new.is_a = lambda c: c == "IfcWall"
+        wall_new.ConnectedTo = []
+        wall_new.ConnectedFrom = []
+
+        old_to_new = {Mock(): [wall_new]}
+
+        with patch.object(tool.Ifc, "get_object", return_value=Mock(spec=bpy.types.Object)), patch.object(
+            tool.Model, "recalculate_walls"
+        ) as recalc_mock:
+            tool.Geometry._recalculate_walls_with_new_connections(old_to_new)
+
+        assert recalc_mock.call_count == 0, "walls with no new connections must not trigger a recalc pass"
+
+    def test_non_wall_entities_are_skipped(self):
+        from unittest.mock import Mock
+
+        actuator_new = Mock()
+        actuator_new.is_a = lambda c: c == "IfcActuator"
+        actuator_new.ConnectedTo = [Mock()]
+
+        old_to_new = {Mock(): [actuator_new]}
+
+        with patch.object(tool.Ifc, "get_object", return_value=Mock(spec=bpy.types.Object)), patch.object(
+            tool.Model, "recalculate_walls"
+        ) as recalc_mock:
+            tool.Geometry._recalculate_walls_with_new_connections(old_to_new)
+
+        assert recalc_mock.call_count == 0
+
+    def test_multiple_new_walls_collected_into_one_call(self):
+        from unittest.mock import Mock
+
+        wall_a_new = Mock()
+        wall_a_new.is_a = lambda c: c == "IfcWall"
+        wall_a_new.ConnectedTo = [Mock()]
+        wall_a_new.ConnectedFrom = []
+        wall_b_new = Mock()
+        wall_b_new.is_a = lambda c: c == "IfcWall"
+        wall_b_new.ConnectedTo = []
+        wall_b_new.ConnectedFrom = [Mock()]
+
+        objs = {wall_a_new: Mock(spec=bpy.types.Object), wall_b_new: Mock(spec=bpy.types.Object)}
+        old_to_new = {Mock(): [wall_a_new], Mock(): [wall_b_new]}
+
+        with patch.object(tool.Ifc, "get_object", side_effect=lambda e: objs.get(e)), patch.object(
+            tool.Model, "recalculate_walls"
+        ) as recalc_mock:
+            tool.Geometry._recalculate_walls_with_new_connections(old_to_new)
+
+        assert recalc_mock.call_count == 1
+        assert set(recalc_mock.call_args.args[0]) == {objs[wall_a_new], objs[wall_b_new]}
+
+
+class TestMEPActionGuardsAgainstArrayChildren(NewFile):
+    """Pins the array-child guards on the three MEP-action visibility helpers.
+    Writable MEP actions (add fitting, remove terminal, join, re-edit bend)
+    applied to an array child get wiped by the next regen — gating the icons
+    at the visibility layer prevents that footgun."""
+
+    def test_active_is_flow_segment_returns_false_for_array_child(self):
+        from unittest.mock import Mock
+
+        from bonsai.bim.module.model.mep import _active_is_flow_segment
+
+        obj = Mock(spec=bpy.types.Object)
+        element = Mock()
+        element.is_a = lambda c: c == "IfcFlowSegment"
+
+        with patch.object(tool.Ifc, "get_entity", return_value=element), patch.object(
+            tool.Array, "is_array_child", return_value=True
+        ), patch.object(tool.System, "has_parametric_body", return_value=True):
+            assert _active_is_flow_segment(obj) is False
+
+    def test_active_is_flow_segment_true_for_non_array_parent(self):
+        from unittest.mock import Mock
+
+        from bonsai.bim.module.model.mep import _active_is_flow_segment
+
+        obj = Mock(spec=bpy.types.Object)
+        element = Mock()
+        element.is_a = lambda c: c == "IfcFlowSegment"
+
+        with patch.object(tool.Ifc, "get_entity", return_value=element), patch.object(
+            tool.Array, "is_array_child", return_value=False
+        ), patch.object(tool.System, "has_parametric_body", return_value=True):
+            assert _active_is_flow_segment(obj) is True
+
+    def test_active_is_bend_fitting_returns_false_for_array_child(self):
+        from unittest.mock import Mock
+
+        from bonsai.bim.module.model.mep import _active_is_bend_fitting
+
+        obj = Mock(spec=bpy.types.Object)
+        element = Mock()
+
+        with patch.object(tool.Ifc, "get_entity", return_value=element), patch(
+            "bonsai.bim.module.model.mep._is_bend_fitting", return_value=True
+        ), patch.object(tool.Array, "is_array_child", return_value=True):
+            assert _active_is_bend_fitting(obj) is False
+
+    def test_n_mep_selected_returns_false_when_any_selected_is_array_child(self):
+        from unittest.mock import Mock
+
+        from bonsai.bim.module.model.mep import _n_mep_selected
+
+        obj_a = Mock(spec=bpy.types.Object)
+        obj_b = Mock(spec=bpy.types.Object)
+        element_a = Mock()
+        element_b = Mock()
+
+        def is_array_child(el):
+            return el is element_b
+
+        with patch.object(tool.Blender, "get_selected_objects", return_value=[obj_a, obj_b]), patch.object(
+            tool.Ifc, "get_entity", side_effect=lambda o: element_a if o is obj_a else element_b
+        ), patch.object(tool.System, "is_mep_element", return_value=True), patch.object(
+            tool.Array, "is_array_child", side_effect=is_array_child
+        ):
+            assert _n_mep_selected(2) is False
+
+
+class TestSelectOnlyParent(NewFile):
+    """Pins ``tool.Array.select_only_parent`` — the shared helper wired into
+    both ``bim.regenerate_array`` and ``bim.finish_editing_array`` so the
+    grow / shrink / edit-commit paths converge on the same post-condition:
+    only the parent is selected + active."""
+
+    def test_deselects_children_selects_and_activates_parent(self):
+        obj, element, parent_data = _build_actuator_with_array_pset(count=4)
+        bpy.context.view_layer.objects.active = obj
+        obj.select_set(True)
+        tool.Model.regenerate_array(obj, parent_data)
+        for child_guid in parent_data[0]["children"]:
+            child_element = tool.Ifc.get().by_guid(child_guid)
+            child_obj = tool.Ifc.get_object(child_element)
+            child_obj.select_set(True)
+
+        tool.Array.select_only_parent(obj, bpy.context)
+
+        assert obj in bpy.context.selected_objects
+        assert bpy.context.view_layer.objects.active is obj
+        for child_guid in parent_data[0]["children"]:
+            child_element = tool.Ifc.get().by_guid(child_guid)
+            child_obj = tool.Ifc.get_object(child_element)
+            assert child_obj not in bpy.context.selected_objects
+
+
+class TestIsArrayChild(NewFile):
+    """Pins ``tool.Array.is_array_child`` — the light helper used by the port
+    decorator (and any future per-element guard) to skip array children."""
+
+    def test_returns_false_when_no_bbim_array_pset(self):
+        from unittest.mock import Mock
+
+        element = Mock()
+        with patch("ifcopenshell.util.element.get_pset", return_value=None):
+            assert tool.Array.is_array_child(element) is False
+
+    def test_returns_false_on_the_array_parent_itself(self):
+        from unittest.mock import Mock
+
+        element = Mock()
+        element.GlobalId = "PARENT_GUID"
+        with patch("ifcopenshell.util.element.get_pset", return_value={"Parent": "PARENT_GUID"}):
+            assert tool.Array.is_array_child(element) is False
+
+    def test_returns_true_when_parent_guid_points_elsewhere(self):
+        from unittest.mock import Mock
+
+        element = Mock()
+        element.GlobalId = "CHILD_GUID"
+        with patch("ifcopenshell.util.element.get_pset", return_value={"Parent": "PARENT_GUID"}):
+            assert tool.Array.is_array_child(element) is True
+
+
+class TestOrphanArrayChildPrune(NewFile):
+    """Outliner / keyboard delete of a Bonsai-managed array child bypasses
+    ``bim.delete``'s cascade, leaving the IFC entity and its opening / filling
+    refs behind. Regen must prune these orphans before the main loop or the
+    stale registry entry corrupts the ``batch_host_recut`` drain."""
+
+    def test_orphan_ifc_entity_pruned_from_children_list(self):
+        obj, element, parent_data = _build_actuator_with_array_pset(count=4)
+        bpy.context.view_layer.objects.active = obj
+        tool.Model.regenerate_array(obj, parent_data)
+        assert len(parent_data[0]["children"]) == 3
+
+        orphan_guid = parent_data[0]["children"][1]
+        orphan_element = tool.Ifc.get().by_guid(orphan_guid)
+        orphan_obj = tool.Ifc.get_object(orphan_element)
+        assert orphan_obj is not None
+        bpy.data.objects.remove(orphan_obj, do_unlink=True)
+
+        tool.Model.regenerate_array(obj, parent_data)
+
+        assert (
+            orphan_guid not in parent_data[0]["children"]
+        ), "orphan GUID must be pruned from array['children'] once its Blender object is dead"
+        try:
+            still_there = tool.Ifc.get().by_guid(orphan_guid)
+        except RuntimeError:
+            still_there = None
+        assert still_there is None, "orphan IFC entity must be cascade-removed, not left as a leak"
+
+    def test_regen_completes_when_child_deleted_outside_bim_cascade(self):
+        obj, element, parent_data = _build_actuator_with_array_pset(count=6)
+        bpy.context.view_layer.objects.active = obj
+        tool.Model.regenerate_array(obj, parent_data)
+
+        victim_guid = parent_data[0]["children"][2]
+        victim_element = tool.Ifc.get().by_guid(victim_guid)
+        victim_obj = tool.Ifc.get_object(victim_element)
+        bpy.data.objects.remove(victim_obj, do_unlink=True)
+
+        tool.Model.regenerate_array(obj, parent_data)
+
+        assert len(parent_data[0]["children"]) == 5, "regen must rebuild to the target count after pruning the orphan"
+        for guid in parent_data[0]["children"]:
+            child = tool.Ifc.get().by_guid(guid)
+            child_obj = tool.Ifc.get_object(child)
+            assert child_obj is not None, "every surviving child must have a live Blender object"
+
+
+class TestRecreatePortConnectionsZipsPairs(NewFile):
+    """Pins the [0]-indexing sweep in tool/duplicate.py recreate_port_connections.
+    When both sides of a port-to-port connection are duplicated N times, the
+    connection must be recreated on every pair of new siblings — not just the
+    first. Matters for arrayed MEP segments (pipes / ducts / cables) where each
+    child in the array should stay connected to its neighbour after regen."""
+
+    def _make_snapshot(self, relating_element, records, port_counts):
+        from bonsai.tool.duplicate import PortConnectionSnapshot
+
+        return PortConnectionSnapshot(
+            by_element={relating_element: records},
+            port_counts=port_counts,
+        )
+
+    def _make_record(self, related_element, relating_port_index=0, related_port_index=0, direction="SOURCE"):
+        from bonsai.tool.duplicate import PortConnectionRecord
+
+        return PortConnectionRecord(
+            relating_port_index=relating_port_index,
+            related_element=related_element,
+            related_port_index=related_port_index,
+            direction=direction,
+        )
+
+    def test_zips_n_pairs_when_both_sides_duplicated(self):
+        from unittest.mock import Mock
+
+        relating_old = Mock()
+        related_old = Mock()
+        record = self._make_record(related_old)
+        snapshot = self._make_snapshot(relating_old, [record], port_counts={})
+
+        old_to_new = {
+            relating_old: [Mock(), Mock(), Mock()],
+            related_old: [Mock(), Mock(), Mock()],
+        }
+
+        fake_ports = [Mock(), Mock()]
+        with patch.object(tool.System, "get_ports", return_value=fake_ports), patch.object(
+            tool.Ifc, "run", return_value=None
+        ) as run_mock:
+            tool.Duplicate.recreate_port_connections(snapshot, old_to_new)
+
+        connect_calls = [c for c in run_mock.call_args_list if c.args and c.args[0] == "system.connect_port"]
+        assert (
+            len(connect_calls) == 3
+        ), f"zip-pair must create 3 connect_port calls for 3-vs-3 batched MEP duplicate; got {len(connect_calls)}"
+
+    def test_skips_when_other_side_not_duplicated(self):
+        from unittest.mock import Mock
+
+        relating_old = Mock()
+        related_old = Mock()
+        record = self._make_record(related_old)
+        snapshot = self._make_snapshot(relating_old, [record], port_counts={})
+
+        # Only relating side is in old_to_new.
+        old_to_new = {relating_old: [Mock(), Mock(), Mock()]}
+
+        with patch.object(tool.System, "get_ports", return_value=[Mock()]), patch.object(
+            tool.Ifc, "run", return_value=None
+        ) as run_mock:
+            tool.Duplicate.recreate_port_connections(snapshot, old_to_new)
+
+        connect_calls = [c for c in run_mock.call_args_list if c.args and c.args[0] == "system.connect_port"]
+        assert connect_calls == [], "when only one side is in old_to_new, no port connections should be recreated"
+
+    def test_single_pair_case_unchanged(self):
+        """Pre-sweep behavior (1 source -> 1 new) must still work — zip with two 1-element lists."""
+        from unittest.mock import Mock
+
+        relating_old = Mock()
+        related_old = Mock()
+        record = self._make_record(related_old)
+        snapshot = self._make_snapshot(relating_old, [record], port_counts={})
+
+        old_to_new = {relating_old: [Mock()], related_old: [Mock()]}
+
+        with patch.object(tool.System, "get_ports", return_value=[Mock()]), patch.object(
+            tool.Ifc, "run", return_value=None
+        ) as run_mock:
+            tool.Duplicate.recreate_port_connections(snapshot, old_to_new)
+
+        connect_calls = [c for c in run_mock.call_args_list if c.args and c.args[0] == "system.connect_port"]
+        assert len(connect_calls) == 1

src/bonsai/test/bim/module/model/test_mep_actions_visibility.py

@@ -346,7 +346,9 @@ def test_active_is_flow_segment_classifies_segment_vs_fitting():
     fitting_elem.is_a = lambda c: c == "IfcFlowFitting"
 
     plain = Mock()
-    with patch("bonsai.bim.module.model.mep.tool.System.has_parametric_body", return_value=True):
+    with patch("bonsai.bim.module.model.mep.tool.System.has_parametric_body", return_value=True), patch(
+        "bonsai.bim.module.model.mep.tool.Array.is_array_child", return_value=False
+    ):
         with patch("bonsai.bim.module.model.mep.tool.Ifc.get_entity", return_value=segment_elem):
             assert _active_is_flow_segment(plain) is True
         with patch("bonsai.bim.module.model.mep.tool.Ifc.get_entity", return_value=fitting_elem):

src/bonsai/test/bim/module/model/test_mep_distribution_fit_smoke.py

@@ -146,7 +146,9 @@ def test_fit_flow_segments_with_single_segment_dispatches_obstruction():
         mep.tool.Model, "get_flow_segment_profile", return_value=segment_profile
     ), patch.object(mep.MEPAddObstruction, "_execute", return_value=None) as obstruction, patch.object(
         mep.MEPAddBend, "_execute", return_value=None
-    ) as bend, patch.object(mep.MEPAddTransition, "_execute", return_value=None) as transition:
+    ) as bend, patch.object(
+        mep.MEPAddTransition, "_execute", return_value=None
+    ) as transition:
         mep.FitFlowSegments._execute(op, context=context)
 
     assert obstruction.call_count == 1
@@ -178,7 +180,9 @@ def test_fit_flow_segments_refuses_mixed_pipe_and_duct():
         mep.tool.Model, "get_flow_segment_profile", return_value=profile
     ), patch.object(mep.MEPAddObstruction, "_execute", return_value=None) as obstruction, patch.object(
         mep.MEPAddBend, "_execute", return_value=None
-    ) as bend, patch.object(mep.MEPAddTransition, "_execute", return_value=None) as transition:
+    ) as bend, patch.object(
+        mep.MEPAddTransition, "_execute", return_value=None
+    ) as transition:
         mep.FitFlowSegments._execute(op, context=context)
 
     obstruction.assert_not_called()

src/bonsai/test/bim/module/model/test_mep_segment_edition.py

@@ -173,8 +173,9 @@ def test_gizmo_group_class_wiring(gizmo_cls_name, bl_idname, is_element_predicat
     predicate = getattr(tool.Parametric, is_element_predicate)
     fake_element = Mock()
     fake_element.is_a.return_value = True
-    with patch.object(tool.Parametric, is_element_predicate, side_effect=predicate) as p, patch.object(
-        tool.System, "has_parametric_body", return_value=True
+    with (
+        patch.object(tool.Parametric, is_element_predicate, side_effect=predicate) as p,
+        patch.object(tool.System, "has_parametric_body", return_value=True),
     ):
         cls.is_element_type(fake_element)
     assert p.called, f"{gizmo_cls_name}.is_element_type did not delegate to Parametric.{is_element_predicate}"

src/bonsai/test/bim/module/project/test_autosave.py

@@ -0,0 +1,68 @@
+# Bonsai - OpenBIM Blender Add-on
+# Copyright (C) 2026
+#
+# This file is part of Bonsai.
+#
+# Bonsai is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# Bonsai is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with Bonsai.  If not, see <http://www.gnu.org/licenses/>.
+#
+# This file was generated with the assistance of an AI coding tool.
+
+import os
+import time
+from pathlib import Path
+
+import pytest
+
+from bonsai.tool.autosave import AUTOSAVED_SUFFIX, AUTOSAVING_SUFFIX, Autosave
+
+pytestmark = pytest.mark.project
+
+
+class TestAutosavePaths:
+    def test_get_paths_for_ifc_file(self):
+        main_path, autosaving_path, autosaved_path = Autosave.get_paths("/tmp/myfile.ifc")
+        assert main_path == Path("/tmp/myfile.ifc")
+        assert autosaving_path == Path(f"/tmp/myfile{AUTOSAVING_SUFFIX}")
+        assert autosaved_path == Path(f"/tmp/myfile{AUTOSAVED_SUFFIX}")
+
+    def test_get_newer_autosaved_path_when_missing(self, tmp_path):
+        ifc_path = tmp_path / "myfile.ifc"
+        ifc_path.write_text("ifc")
+        assert Autosave.get_newer_autosaved_path(ifc_path) is None
+
+    def test_get_newer_autosaved_path_when_older(self, tmp_path):
+        ifc_path = tmp_path / "myfile.ifc"
+        autosaved_path = tmp_path / f"myfile{AUTOSAVED_SUFFIX}"
+        ifc_path.write_text("ifc")
+        autosaved_path.write_text("autosaved")
+        past = time.time() - 10
+        os.utime(ifc_path, (past, past))
+        os.utime(autosaved_path, (time.time(), time.time()))
+        assert Autosave.get_newer_autosaved_path(ifc_path) == autosaved_path.as_posix()
+
+    def test_get_newer_autosaved_path_when_not_newer(self, tmp_path):
+        ifc_path = tmp_path / "myfile.ifc"
+        autosaved_path = tmp_path / f"myfile{AUTOSAVED_SUFFIX}"
+        ifc_path.write_text("ifc")
+        autosaved_path.write_text("autosaved")
+        now = time.time()
+        os.utime(ifc_path, (now, now))
+        past = now - 10
+        os.utime(autosaved_path, (past, past))
+        assert Autosave.get_newer_autosaved_path(ifc_path) is None
+
+    def test_get_newer_autosaved_path_ignores_non_ifc(self, tmp_path):
+        path = tmp_path / "myfile.ifczip"
+        path.write_text("zip")
+        assert Autosave.get_newer_autosaved_path(path) is None

src/bonsai/test/bim/test_preview_cancel_ops_forward_compat.py

@@ -139,6 +139,5 @@ def test_every_cancel_ops_entry_has_a_real_preview_propertygroup() -> None:
     orphaned = [attr for attr, _op in preview_base.PREVIEW_CANCEL_OPS if attr not in declared_attrs]
     assert not orphaned, (
         "PREVIEW_CANCEL_OPS contains entries whose PointerProperty child no longer "
-        f"exists on {UMBRELLA_CLASS}. Drop the stale tuple(s):\n  "
-        + "\n  ".join(orphaned)
+        f"exists on {UMBRELLA_CLASS}. Drop the stale tuple(s):\n  " + "\n  ".join(orphaned)
     )

src/bonsai/test/core/test_unit.py

@@ -174,6 +174,15 @@ class TestAddConversionBasedUnit:
         assert subject.add_conversion_based_unit(ifc, unit, name="name") == "unit"
 
 
+class TestAddDerivedUnit:
+    def test_run(self, ifc, unit):
+        ifc.run(
+            "unit.add_derived_unit", unit_type="unit_type", userdefinedtype=None, attributes="elements"
+        ).should_be_called().will_return("unit")
+        unit.import_units().should_be_called()
+        assert subject.add_derived_unit(ifc, unit, unit_type="unit_type", elements="elements") == "unit"
+
+
 class TestEnableEditingUnit:
     def test_run(self, unit):
         unit.set_active_unit("unit").should_be_called()

src/bonsai/test/modal/test_modal.py

@@ -24,6 +24,7 @@ import time
 
 import bpy
 import ifcopenshell
+import ifcopenshell.util.element
 import pytest
 
 from bonsai import tool as tool

src/bonsai/test/tool/test_geometry_batch_host_recut.py

@@ -164,6 +164,62 @@ def test_stale_element_skipped_at_drain():
     assert recut.call_count == 0
 
 
+class _DeadStructRNA:
+    """Simulates a Blender object whose StructRNA has been removed — every
+    attribute access raises ReferenceError. Enqueue this as voided_obj to
+    reproduce the outliner-mid-batch-delete crash."""
+
+    def __getattr__(self, name):
+        raise ReferenceError("StructRNA of type Object has been removed")
+
+    def __bool__(self):
+        raise ReferenceError("StructRNA of type Object has been removed")
+
+
+def test_dead_structrna_recut_skipped_at_drain():
+    """Blender object is deleted while the batch is open (outliner delete +
+    manual DEL bypass the bim.delete cascade). The drain must skip it silently
+    — not raise — so unrelated hosts in the same batch still get their recut."""
+    from bonsai import tool
+
+    dead_obj = _DeadStructRNA()
+    live_obj = _mock_voided_obj("LiveWall")
+    rep = Mock()
+
+    def get_entity(obj):
+        # Called only when the guard clears — for the dead ref, guard short-circuits first.
+        return _mock_element(2)
+
+    with patch("bonsai.core.geometry.switch_representation") as recut, patch.object(
+        tool.Ifc, "get_entity", side_effect=get_entity
+    ), patch.object(tool.Geometry, "get_active_representation", return_value=rep):
+        with tool.Geometry.batch_host_recut():
+            tool.Geometry._host_recut_queue[999] = (dead_obj, rep)
+            tool.Geometry.recut_host(live_obj, rep)
+
+    assert recut.call_count == 1, "live host must still get its recut despite a dead sibling in the queue"
+    drained_obj = recut.call_args.kwargs["obj"]
+    assert drained_obj is live_obj
+
+
+def test_dead_structrna_update_skipped_at_drain():
+    """Same guarantee for update_representation drain path."""
+    from bonsai import tool
+
+    dead_obj = _DeadStructRNA()
+    live_obj = _mock_voided_obj("LiveWall")
+    bpy_ops_mock = Mock()
+
+    with patch("bonsai.tool.geometry.bpy.ops", new=bpy_ops_mock), patch.object(
+        tool.Ifc, "get_entity", return_value=_mock_element(42)
+    ), patch.object(tool.Geometry, "get_active_representation", return_value=Mock()):
+        with tool.Geometry.batch_host_recut():
+            tool.Geometry._host_update_queue[999] = dead_obj
+            tool.Geometry.update_host_representation(live_obj)
+
+    assert bpy_ops_mock.bim.update_representation.call_count == 1
+
+
 def test_exception_inside_batch_still_resets_state():
     from bonsai import tool
 

src/bonsai/test/tool/test_model.py

@@ -23,6 +23,7 @@ import bpy
 import ifcopenshell
 import ifcopenshell.api.geometry
 import ifcopenshell.api.material
+import ifcopenshell.api.pset
 import ifcopenshell.api.root
 import ifcopenshell.api.style
 import ifcopenshell.api.type
@@ -630,15 +631,15 @@ class TestUsingArrays(NewFile):
     def test_remove_array_first_to_last(self):
         self.setup_array(add_second_layer=True)
         bpy.ops.bim.remove_array(item=0)
-        assert len(bpy.context.selected_objects) == 3
+        assert len(self._array_objects()) == 3
         bpy.ops.bim.remove_array(item=0)
-        assert len(bpy.context.selected_objects) == 1
+        assert len(self._array_objects()) == 1
 
     def test_apply_array_1_layer(self):
         self.setup_array()
         bpy.ops.bim.apply_array()
 
-        objs = bpy.context.selected_objects
+        objs = self._array_objects()
         assert len(objs) == 4
         # check BBIM_Array psets are removed
         for obj in objs:
@@ -664,7 +665,7 @@ class TestUsingArrays(NewFile):
         self.setup_array(sync_children=True)
         bpy.ops.bim.apply_array()
 
-        objs = bpy.context.selected_objects
+        objs = self._array_objects()
         assert len(objs) == 4
         # check BBIM_Array psets are removed
         for obj in objs:

src/ifc5d/ifc5d/csv2ifc.py

@@ -57,7 +57,8 @@ class CsvHeader(TypedDict):
 
     # Formula
     Formula: NotRequired[str]
-    #QuantityClass: NotRequired[str]
+    # QuantityClass: NotRequired[str]
+
 
 # Currently we assume that if column is not part of the main header,
 # then it is a cost value category. So here we list any additional column
@@ -97,7 +98,8 @@ class CostItem(TypedDict):
     Query: Union[str, None]
 
     Formula: Union[str, None]
-    #QuantityClass: Union[str, None]
+    # QuantityClass: Union[str, None]
+
 
 class Csv2Ifc:
     # Inputs.
@@ -420,7 +422,7 @@ class Csv2Ifc:
                     products=results,
                     formula=cost_item["Formula"],
                     ifc_class=ifc_quantity_class,
-                    )
+                )
 
         self.create_cost_items(cost_item["children"], cost_item["ifc"])
 

src/ifcconvert/IfcConvert.cpp

@@ -252,6 +252,10 @@ int main(int argc, char** argv) {
 		("stderr-progress", "output progress to stderr stream")
 		("yes,y", "answer 'yes' automatically to possible confirmation queries (e.g. overwriting an existing output file)")
 		("no-progress", "suppress possible progress bar type of prints that use carriage return")
+		("fail-on-error", "return a non-zero exit code when one or more errors were logged during "
+			"geometry conversion (e.g. an element failed to convert). By default IfcConvert exits "
+			"successfully as long as an output file could be written, even if some elements were "
+			"silently dropped. Enable this flag so scripts and CI can detect partial conversions.")
 		("log-format", po::value<std::string>(&log_format), "log format: plain or json")
 		("log-file", new po::typed_value<path_t, char_t>(&log_file), "redirect log output to file");
 
@@ -449,6 +453,7 @@ int main(int argc, char** argv) {
 
 	const bool mmap = vmap.count("mmap") != 0;
 	const bool no_progress = vmap.count("no-progress") != 0;
+	const bool fail_on_error = vmap.count("fail-on-error") != 0;
 	const bool quiet = vmap.count("quiet") != 0;
 	const bool stderr_progress = vmap.count("stderr-progress") != 0;
 
@@ -885,6 +890,7 @@ int main(int argc, char** argv) {
 	}
 
 	if (!serializer->ready()) {
+		logger.Error("SYS", 25, "Unable to open output file '" + IfcUtil::path::to_utf8(output_filename) + "' for writing; check that the directory exists and is writable");
 		IfcUtil::path::delete_file(IfcUtil::path::to_utf8(output_temp_filename));
 		write_log(!quiet);
 		return EXIT_FAILURE;
@@ -1220,6 +1226,11 @@ int main(int argc, char** argv) {
 		successful = false;
 	}
 
+	if (fail_on_error && logger.MaxSeverity() >= Logger::LOG_ERROR) {
+		logger.Error("SYS", 26, "Errors encountered during processing, failing due to --fail-on-error.");
+		successful = false;
+	}
+
 	if (logger.Verbosity() == Logger::LOG_PERF) {
 		logger.PrintPerformanceStats();
 	}

src/ifcgeom/ConversionSettings.h

@@ -361,8 +361,8 @@ namespace ifcopenshell {
 
 			struct CircleSegments : public SettingBase<CircleSegments, int> {
 				static constexpr const char* const name = "circle-segments";
-				static constexpr const char* const description = "Number of segments to approximate full circles in CGAL kernel.";
-				static constexpr int defaultvalue = 16;
+				static constexpr const char* const description = "Number of segments to approximate full circles in the CGAL kernel. When 0 (the default) the segment count is derived from mesher-linear-deflection instead, so curves stay within the deflection tolerance regardless of radius.";
+				static constexpr int defaultvalue = 0;
 			};
 
 			struct CgalSmoothAngleDegrees : public SettingBase<CgalSmoothAngleDegrees, double> {

src/ifcgeom/kernels/cgal/CgalKernel.cpp

@@ -391,6 +391,11 @@ namespace {
 		}
 	};
 
+	// Representative radius used to size the polygonal approximation of a conic.
+	// For an ellipse the larger semi-axis is the conservative choice.
+	inline double conic_radius(const taxonomy::circle::ptr& c) { return c->radius; }
+	inline double conic_radius(const taxonomy::ellipse::ptr& e) { return e->radius > e->radius2 ? e->radius : e->radius2; }
+
 	struct cgal_curve_creation_visitor {
 		Settings& settings_;
 		parameter_range param;
@@ -425,7 +430,36 @@ namespace {
 			if (b <= a) {
 				b += 2 * M_PI;
 			}
-			int num_segments = (int)std::ceil(std::fabs(a - b) / (2 * M_PI) * settings_.get<settings::CircleSegments>().get());
+			const double span = std::fabs(a - b);
+			// CircleSegments controls how conics (circles, ellipses, arcs) are approximated
+			// in the CGAL kernel. Two modes, one or the other:
+			//  - CircleSegments == 0 (the default): the segment count is derived from
+			//    MesherLinearDeflection, so the chord deviation stays within the mesher's
+			//    linear deflection regardless of radius. This matches the deflection based
+			//    meshing the OpenCascade kernel already does and fixes issue #8051, where
+			//    large radius arcs (curved curtain wall mullions) collapsed to straight chords
+			//    because a fixed segment count is radius agnostic.
+			//  - CircleSegments > 0: it is used directly as the number of segments for a full
+			//    circle, giving deterministic, radius independent output.
+			int num_segments;
+			const int circle_segments = settings_.get<settings::CircleSegments>().get();
+			if (circle_segments > 0) {
+				num_segments = (int)std::ceil(span / (2 * M_PI) * circle_segments);
+			} else {
+				const double radius = conic_radius(t);
+				const double deflection = settings_.get<settings::MesherLinearDeflection>().get();
+				if (deflection > 0. && radius > deflection) {
+					const double max_segment_angle = 2.0 * std::acos(1.0 - deflection / radius);
+					num_segments = (int)std::ceil(span / max_segment_angle);
+				} else {
+					// Radius within the deflection tolerance (or no deflection set): a chord per
+					// quarter turn already keeps the deviation within tolerance.
+					num_segments = (int)std::ceil(span / (M_PI / 2.));
+				}
+			}
+			if (num_segments < 1) {
+				num_segments = 1;
+			}
 			double du = (b - a) / num_segments;
 			taxonomy::point3 P;
 			// @nb for loop is not inclusive of the both end points

src/ifcgeom/kernels/opencascade/face.cpp

@@ -31,6 +31,7 @@
 #include <ShapeFix_Shape.hxx>
 #include <ShapeFix_ShapeTolerance.hxx>
 #include <BRep_Tool.hxx>
+#include <BRepExtrema_DistShapeShape.hxx>
 
 #include <Standard_Macro.hxx>
 #include <TopoDS_Shape.hxx>
@@ -356,6 +357,27 @@ bool OpenCascadeKernel::convert(const taxonomy::face::ptr face, TopoDS_Shape& re
 		return false;
 	}
 
+	// #527: A face whose inner boundary intersects the outer boundary (or
+	// another inner boundary) is invalid per the schema. Open Cascade heals or
+	// drops such a face silently, so the intended hole is lost with no
+	// diagnostic. The distance between two non-intersecting loops is strictly
+	// positive; a distance at (or below) the modelling precision means the
+	// boundaries touch or cross. Emit a clear warning so the invalid input is
+	// not silently lost. wires() is ordered outer-first, inner-bounds after.
+	if (fd.wires().size() > 1) {
+		const auto& fwires = fd.wires();
+		bool reported = false;
+		for (size_t i = 1; i < fwires.size() && !reported; ++i) {
+			for (size_t j = 0; j < i && !reported; ++j) {
+				BRepExtrema_DistShapeShape dss(fwires[i], fwires[j]);
+				if (dss.IsDone() && dss.Value() < precision_) {
+					logger().Warning("GEO", 402, "Face inner boundary intersects another face boundary", face->instance);
+					reported = true;
+				}
+			}
+		}
+	}
+
 	if (fd.surface().IsNull()) {
 		// Use the first wire to find a plane manually for polygonal wires
 		const TopoDS_Wire& wire = fd.wires().front();

src/ifcgeom/mapping/IfcAsymmetricIShapeProfileDef.cpp

@@ -0,0 +1,93 @@
+// This file was generated with the assistance of an AI coding tool.
+/********************************************************************************
+ *                                                                              *
+ * This file is part of IfcOpenShell.                                           *
+ *                                                                              *
+ * IfcOpenShell is free software: you can redistribute it and/or modify         *
+ * it under the terms of the Lesser GNU General Public License as published by  *
+ * the Free Software Foundation, either version 3.0 of the License, or          *
+ * (at your option) any later version.                                          *
+ *                                                                              *
+ * IfcOpenShell is distributed in the hope that it will be useful,              *
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of               *
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the                 *
+ * Lesser GNU General Public License for more details.                          *
+ *                                                                              *
+ * You should have received a copy of the Lesser GNU General Public License     *
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.         *
+ *                                                                              *
+ ********************************************************************************/
+
+#include "mapping.h"
+#define mapping POSTFIX_SCHEMA(mapping)
+using namespace ifcopenshell::geometry;
+
+#include "../profile_helper.h"
+
+// In IFC2X3 IfcAsymmetricIShapeProfileDef is a subtype of IfcIShapeProfileDef and is
+// therefore dispatched (and handled) by the IfcIShapeProfileDef mapping. From IFC4
+// onwards it is a standalone subtype of IfcParameterizedProfileDef with its own
+// Bottom*/Top* attributes, so nothing mapped it and the extrusion came out empty.
+// The presence of the standalone BottomFlangeWidth attribute is the discriminator:
+// it is only defined in the schemas where the type is standalone (IFC4 / IFC4X3).
+#ifdef SCHEMA_IfcAsymmetricIShapeProfileDef_HAS_BottomFlangeWidth
+
+taxonomy::ptr mapping::map_impl(const IfcSchema::IfcAsymmetricIShapeProfileDef* inst) {
+	// Bottom flange (half width), overall depth (half), web (half thickness).
+	const double xb = inst->BottomFlangeWidth() / 2.0 * length_unit_;
+	const double xt = inst->TopFlangeWidth() / 2.0 * length_unit_;
+	const double y = inst->OverallDepth() / 2.0 * length_unit_;
+	const double d1 = inst->WebThickness() / 2.0 * length_unit_;
+
+	// Bottom flange thickness; top flange thickness defaults to the bottom one.
+	const double ftb = inst->BottomFlangeThickness() * length_unit_;
+	const double ftt = inst->TopFlangeThickness().get_value_or(inst->BottomFlangeThickness()) * length_unit_;
+
+	// Optional fillet radii (web/flange transition) and flange edge radii.
+	const double fb = inst->BottomFlangeFilletRadius().get_value_or(0.) * length_unit_;
+	const double ft_top = inst->TopFlangeFilletRadius().get_value_or(0.) * length_unit_;
+	const double feb = inst->BottomFlangeEdgeRadius().get_value_or(0.) * length_unit_;
+	const double fet = inst->TopFlangeEdgeRadius().get_value_or(0.) * length_unit_;
+
+	// Optional flange slopes: the inner edge of the flange rises towards the web.
+	const double bottomSlope = inst->BottomFlangeSlope().get_value_or(0.) * angle_unit_;
+	const double topSlope = inst->TopFlangeSlope().get_value_or(0.) * angle_unit_;
+	const double dyb = (xb - d1) * tan(bottomSlope);
+	const double dyt = (xt - d1) * tan(topSlope);
+
+	const double tol = settings_.get<settings::Precision>().get();
+
+	if (xb < tol || xt < tol || y < tol || d1 < tol || ftb < tol || ftt < tol) {
+		logger_.Message(Logger::LOG_NOTICE, "GEO", 264, "Skipping zero sized profile:", inst);
+		return nullptr;
+	}
+
+	taxonomy::matrix4::ptr m4;
+	bool has_position = true;
+#ifdef SCHEMA_IfcParameterizedProfileDef_Position_IS_OPTIONAL
+	has_position = !!inst->Position();
+#endif
+	if (has_position) {
+		m4 = taxonomy::cast<taxonomy::matrix4>(map(inst->Position()));
+	}
+
+	// Twelve corner points, running counter-clockwise from the bottom-left, with the
+	// bottom flange (xb) possibly wider than the top flange (xt). Fillet/edge radii are
+	// attached to the corner they round, matching the symmetric IfcIShapeProfileDef.
+	return profile_helper(m4, {
+		{{-xb,-y}},
+		{{xb,-y}},
+		{{xb,-y + ftb}, {feb}},
+		{{d1,-y + ftb + dyb},{fb} },
+		{{d1,y - ftt - dyt},{ft_top} },
+		{{xt,y - ftt}, {fet}},
+		{{xt,y}},
+		{{-xt,y}},
+		{{-xt,y - ftt}, {fet}},
+		{{-d1,y - ftt - dyt},{ft_top} },
+		{{-d1,-y + ftb + dyb},{fb} },
+		{{-xb,-y + ftb}, {feb}}
+	});
+}
+
+#endif

src/ifcgeom/mapping/IfcPolygonalFaceSet.cpp

@@ -39,8 +39,25 @@ taxonomy::ptr mapping::map_impl(const IfcSchema::IfcPolygonalFaceSet* inst) {
 
 	int max_index = (int)points.size();
 
+	// When the optional PnIndex is present, CoordIndex values do not index into
+	// CoordList directly but into PnIndex, which in turn remaps to CoordList.
+	// Both index levels are 1-based per the IFC specification.
+	auto pn_index = inst->PnIndex();
+	auto resolve = [&](int idx) -> const taxonomy::point3::ptr& {
+		if (pn_index) {
+			if (idx < 1 || idx > (int)pn_index->size()) {
+				throw IfcParse::IfcException("IfcPolygonalFaceSet PnIndex out of bounds for index " + boost::lexical_cast<std::string>(idx));
+			}
+			idx = (*pn_index)[idx - 1];
+		}
+		if (idx < 1 || idx > max_index) {
+			throw IfcParse::IfcException("IfcPolygonalFaceSet index out of bounds for index " + boost::lexical_cast<std::string>(idx));
+		}
+		return points[idx - 1];
+	};
+
 	auto shell = taxonomy::make<taxonomy::shell>();
-	
+
 	for (auto& f : *polygonal_faces) {
 		auto fa = taxonomy::make<taxonomy::face>();
 		shell->children.push_back(fa);
@@ -52,17 +69,14 @@ taxonomy::ptr mapping::map_impl(const IfcSchema::IfcPolygonalFaceSet* inst) {
 			auto indices = f->CoordIndex();
 			taxonomy::point3::ptr previous;
 			for (std::vector<int>::const_iterator jt = indices.begin(); jt != indices.end(); ++jt) {
-				if (*jt < 1 || *jt > max_index) {
-					throw IfcParse::IfcException("IfcPolygonalFaceSet index out of bounds for index " + boost::lexical_cast<std::string>(*jt));
-				}
-				auto current = points[(*jt) - 1];
+				auto current = resolve(*jt);
 				if (jt != indices.begin()) {
 					loop->children.push_back(taxonomy::make<taxonomy::edge>(previous, current));
 				}
 				previous = current;
 			}
 			if (!indices.empty()) {
-				auto current = points[indices.front() - 1];
+				auto current = resolve(indices.front());
 				loop->children.push_back(taxonomy::make<taxonomy::edge>(previous, current));
 			}
 		}
@@ -77,17 +91,14 @@ taxonomy::ptr mapping::map_impl(const IfcSchema::IfcPolygonalFaceSet* inst) {
 					loop->external = false;
 
 					for (std::vector<int>::const_iterator jt = li.begin(); jt != li.end(); ++jt) {
-						if (*jt < 1 || *jt > max_index) {
-							throw IfcParse::IfcException("IfcPolygonalFaceSet index out of bounds for index " + boost::lexical_cast<std::string>(*jt));
-						}
-						auto current = points[(*jt) - 1];
+						auto current = resolve(*jt);
 						if (jt != li.begin()) {
 							loop->children.push_back(taxonomy::make<taxonomy::edge>(previous, current));
 						}
 						previous = current;
 					}
 					if (!li.empty()) {
-						auto current = points[li.front() - 1];
+						auto current = resolve(li.front());
 						loop->children.push_back(taxonomy::make<taxonomy::edge>(previous, current));
 					}
 				}

src/ifcgeom/mapping/IfcTriangulatedFaceSet.cpp

@@ -39,6 +39,23 @@ taxonomy::ptr mapping::map_impl(const IfcSchema::IfcTriangulatedFaceSet* inst) {
 
 	int max_index = (int)points.size();
 
+	// When the optional PnIndex is present, CoordIndex values do not index into
+	// CoordList directly but into PnIndex, which in turn remaps to CoordList.
+	// Both index levels are 1-based per the IFC specification.
+	auto pn_index = inst->PnIndex();
+	auto resolve = [&](int idx) -> const taxonomy::point3::ptr& {
+		if (pn_index) {
+			if (idx < 1 || idx > (int)pn_index->size()) {
+				throw IfcParse::IfcException("IfcTriangulatedFaceSet PnIndex out of bounds for index " + boost::lexical_cast<std::string>(idx));
+			}
+			idx = (*pn_index)[idx - 1];
+		}
+		if (idx < 1 || idx > max_index) {
+			throw IfcParse::IfcException("IfcTriangulatedFaceSet index out of bounds for index " + boost::lexical_cast<std::string>(idx));
+		}
+		return points[idx - 1];
+	};
+
 	auto shell = taxonomy::make<taxonomy::shell>();
 
 	for (auto& indices : indices_list) {
@@ -51,10 +68,7 @@ taxonomy::ptr mapping::map_impl(const IfcSchema::IfcTriangulatedFaceSet* inst) {
 			loop->external = true;
 			taxonomy::point3::ptr first, previous;
 			for (std::vector<int>::const_iterator jt = indices.begin(); jt != indices.end(); ++jt) {
-				if (*jt < 1 || *jt > max_index) {
-					throw IfcParse::IfcException("IfcTriangulatedFaceSet index out of bounds for index " + boost::lexical_cast<std::string>(*jt));
-				}
-				const taxonomy::point3::ptr& current = points[(*jt) - 1];
+				const taxonomy::point3::ptr& current = resolve(*jt);
 				if (jt == indices.begin()) {
 					first = current;
 				} else {

src/ifcgeom/mapping/mapping.i

@@ -89,7 +89,11 @@ BIND(IfcRectangleHollowProfileDef);
 BIND(IfcRectangleProfileDef);
 BIND(IfcTrapeziumProfileDef);
 BIND(IfcCShapeProfileDef);
-// IfcAsymmetricIShapeProfileDef included
+// In IFC2X3 IfcAsymmetricIShapeProfileDef is a subtype of IfcIShapeProfileDef and is
+// mapped by it; from IFC4 onwards it is a standalone type and needs its own binding.
+#ifdef SCHEMA_IfcAsymmetricIShapeProfileDef_HAS_BottomFlangeWidth
+BIND(IfcAsymmetricIShapeProfileDef);
+#endif
 BIND(IfcIShapeProfileDef);
 BIND(IfcLShapeProfileDef);
 BIND(IfcTShapeProfileDef);

src/ifcopenshell-python/docs/ifcconvert/usage.rst

@@ -311,8 +311,12 @@ CLI Manual
                                             output.
       --force-space-transparency arg        Overrides transparency of spaces in 
                                             geometry output.
-      --circle-segments arg (= 16)          Number of segments to approximate full 
-                                            circles in CGAL kernel.
+      --circle-segments arg (= 0)           Number of segments to approximate full
+                                            circles in the CGAL kernel. When 0 (the
+                                            default) the segment count is derived from
+                                            mesher-linear-deflection instead, so curves
+                                            stay within the deflection tolerance
+                                            regardless of radius.
       --cgal-smooth-angle-degrees arg (= -1)
                                             Angle in degrees under which adjacent 
                                             facets will have averaged vertex 

src/ifcopenshell-python/docs/ifcopenshell-python/selector_syntax.rst

@@ -72,6 +72,8 @@ Filtering is typically used to select any IFC element or type.
 
     "``IfcPump, location=""Level 3""``", "Locations bubble up the hierarchy. So if a pump is in a space and that space is on Level 3, then you can say ""all pumps on level 3"" which will include that pump in the space."
 
+    "``IfcElement, query:""parent.Name""=""My Site""``", "Only elements *immediately* under ""My Site"" in the spatial hierarchy. Unlike the ``location`` and ``parent`` filters, which both match at any depth, the ``parent`` query key resolves the direct parent only, so nested storeys (and their contents) are excluded."
+
 The filter elements syntax works by specifying one or more groups of filters
 separated by a ``+`` character. Each filter group will return a set of filtered
 elements, and these are unioned together.
@@ -111,6 +113,15 @@ will search through all IfcTypeProducts and IfcProducts in the IFC project.
     "Parent", "Filter", "``parent{{=}}{{value}}``", "``parent=Foo`` specifies the criteria that elements must be a direct or indirect child in the spatial hierarchy to an element with a ``Name`` attribute with a value of ``Foo``."
     "Query", "Filter", "``query:{{keys}}{{=}}{{value}}``", "``query:types.count=0`` specifies the criteria that elements must have zero type occurrences. The query keys corresponds to the syntax used in the `Getting element values`_ section"
 
+.. note::
+
+    The ``location`` and ``parent`` filters both match at **any depth** in the
+    spatial hierarchy. To match only elements *immediately* contained in (or
+    aggregated under) a spatial element, use the ``parent`` query key, which
+    resolves the direct parent only. For example,
+    ``query:"parent.Name"="My Site"`` selects elements directly under ``My
+    Site`` but excludes anything nested inside its sub-storeys or spaces.
+
 When you specify a filter with a ``{{=}}`` check, you can choose from one of
 the following comparison checks:
 
@@ -191,7 +202,7 @@ Valid keys are:
     "``storey``", "Gets the first IfcBuildingStorey spatial element that an element is contained in."
     "``building``", "Gets the first IfcBuilding spatial element that an element is contained in."
     "``site``", "Gets the first IfcSite spatial element that an element is contained in."
-    "``parent``", "Gets the parent element in the spatial hierarchy."
+    "``parent``", "Gets the **immediate** parent element in the spatial hierarchy (the direct spatial container, or the direct aggregate/nest/fill/void parent). Combine with ``.Name`` in a query filter to match only immediate children, e.g. ``query:""parent.Name""=""My Site""``."
     "``classification``", "Gets the element's classification reference(s)"
     "``group``", "Gets the element's group(s)"
     "``system``", "Gets the element's system(s). This is a subset of group(s)."

src/ifcopenshell-python/docs/ifcopenshell/geometry_settings.rst

@@ -228,10 +228,10 @@ circle-segments
 +------+-----------------------+---------+
 | Type | IfcConvert Option     | Default |
 +======+=======================+=========+
-| INT  | ``--circle-segments`` | 16      |
+| INT  | ``--circle-segments`` | 0       |
 +------+-----------------------+---------+
 
-Number of segments to approximate full circles in CGAL kernel.
+Number of segments to approximate full circles in the CGAL kernel. When 0 (the default) the segment count is derived from mesher-linear-deflection instead, so curves stay within the deflection tolerance regardless of radius.
 
 context-identifiers
 ^^^^^^^^^^^^^^^^^^^

src/ifcopenshell-python/ifcopenshell/__init__.py

@@ -231,7 +231,7 @@ def open(
         kwargs = {"mmap": mmap}
         if logger is not None:
             kwargs["logger"] = logger
-        f = ifcopenshell_wrapper.open(str(path.absolute()), **kwargs)  # ty: ignore[unknown-argument]
+        f = ifcopenshell_wrapper.open(str(path.absolute()), **kwargs)
     else:
         f = ifcopenshell_wrapper.open(str(path.absolute()), False, *((logger,) if logger is not None else ()))
     return file(f)

src/ifcopenshell-python/ifcopenshell/api/alignment/__init__.py

@@ -49,6 +49,7 @@ Future versions of this API may support:
 
 from ._get_segment_start_point_label import register_referent_name_callback
 from .add_stationing_referent import add_stationing_referent
+from .add_positioning_referent import add_positioning_referent
 from .add_vertical_layout import add_vertical_layout
 from .add_zero_length_segment import add_zero_length_segment
 from .create import create
@@ -94,6 +95,7 @@ from .util import *
 
 __all__ = [
     "add_stationing_referent",
+    "add_positioning_referent",
     "add_vertical_layout",
     "add_zero_length_segment",
     "create",

src/ifcopenshell-python/ifcopenshell/api/alignment/_add_segment_to_curve.py

@@ -22,8 +22,6 @@ import numpy as np
 import ifcopenshell
 import ifcopenshell.api.alignment
 import ifcopenshell.geom
-import ifcopenshell.ifcopenshell_wrapper as ifcopenshell_wrapper
-import ifcopenshell.util.unit
 from ifcopenshell import entity_instance
 from ifcopenshell.api.alignment._get_segment_endpoint import _get_segment_endpoint
 from ifcopenshell.api.alignment._update_zero_length_segment_placement import _update_zero_length_segment_placement

src/ifcopenshell-python/ifcopenshell/api/alignment/_add_segment_to_layout.py

@@ -22,28 +22,11 @@ import numpy as np
 
 import ifcopenshell
 import ifcopenshell.api.alignment
-from ifcopenshell.api.alignment import _map_alignment_cant_segment
 from ifcopenshell.api.alignment._update_zero_length_segment_placement import _update_zero_length_segment_placement
 import ifcopenshell.api.nest
-import ifcopenshell.api.pset
-import ifcopenshell.geom
-import ifcopenshell.util.alignment
-import ifcopenshell.util.unit
-from ifcopenshell import entity_instance, ifcopenshell_wrapper
+from ifcopenshell import entity_instance
 from ifcopenshell.api.alignment._add_segment_to_curve import _add_segment_to_curve
 from ifcopenshell.api.alignment._get_segment_endpoint import _get_segment_endpoint
-from ifcopenshell.api.alignment._get_segment_start_point_label import (
-    _get_segment_start_point_label,
-)
-from ifcopenshell.api.alignment._map_alignment_cant_segment import (
-    _map_alignment_cant_segment,
-)
-from ifcopenshell.api.alignment._map_alignment_horizontal_segment import (
-    _map_alignment_horizontal_segment,
-)
-from ifcopenshell.api.alignment._map_alignment_vertical_segment import (
-    _map_alignment_vertical_segment,
-)
 
 
 def _add_segment_to_layout(

src/ifcopenshell-python/ifcopenshell/api/alignment/_add_zero_length_segment.py

@@ -18,11 +18,7 @@
 
 import ifcopenshell
 import ifcopenshell.api.alignment
-import ifcopenshell.util.alignment
 from ifcopenshell import entity_instance
-from ifcopenshell.api.alignment._get_segment_start_point_label import (
-    _get_segment_start_point_label,
-)
 
 
 def _add_zero_length_segment(file: ifcopenshell.file, layout: entity_instance) -> None:

src/ifcopenshell-python/ifcopenshell/api/alignment/_get_segment_endpoint.py

@@ -18,6 +18,7 @@
 
 
 import ifcopenshell.api.alignment
+import ifcopenshell.geom
 from ifcopenshell import entity_instance, ifcopenshell_wrapper
 from ifcopenshell.api.alignment._map_alignment_segment import _map_alignment_segment
 from typing import Union

src/ifcopenshell-python/ifcopenshell/api/alignment/add_positioning_referent.py

@@ -0,0 +1,113 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2025 Thomas Krijnen <thomas@aecgeeks.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+
+import ifcopenshell
+import ifcopenshell.api.alignment
+from ifcopenshell.api.alignment.update_fallback_position import update_fallback_position
+import ifcopenshell.api.pset
+import ifcopenshell.guid
+from ifcopenshell import entity_instance
+
+
+def add_positioning_referent(
+    file: ifcopenshell.file,
+    name: str,
+    alignment: entity_instance,
+    distance_along: float,
+    station: float,
+    positioned_product: entity_instance,
+) -> entity_instance:
+    """
+    Semantically defines the position of a product along an alignment by adding an IfcReferent to the alignment that defines the stationing system.
+
+    :param alignment: the alignment to receive the referent
+    :param distance_along: distance along the alignment basis curve
+    :param station: station value
+    :param name: name to assign to IfcReferent.Name, typically a stringized version of the station value
+    :param positioned_product: the product whose position is informed by the referent
+    :return: referent
+
+    Example:
+
+    .. code:: python
+
+        alignment = model.by_type("IfcAlignment")[0]
+        pier = model.by_type("IfcBridgePart")[0]
+        ifcopenshell.api.alignment.add_positioning_referent(model,name="Pier 1 Sta 1+00",alignment=alignment,distance_along=0.0,station=100.0,positioned_product=pier)
+    """
+
+    curve = ifcopenshell.api.alignment.get_curve(alignment)
+
+    object_placement = None
+    representation = None
+    if curve and curve.is_a("IfcCompositeCurve") and 0 < len(curve.Segments):
+        object_placement = file.createIfcLinearPlacement(
+            RelativePlacement=file.createIfcAxis2PlacementLinear(
+                Location=file.createIfcPointByDistanceExpression(
+                    DistanceAlong=file.createIfcLengthMeasure(distance_along),
+                    OffsetLateral=None,
+                    OffsetVertical=None,
+                    OffsetLongitudinal=None,
+                    BasisCurve=curve,
+                )
+            ),
+        )
+
+        update_fallback_position(file, object_placement)
+    else:
+        object_placement = file.createIfcLocalPlacement(
+            PlacementRelTo=None,
+            RelativePlacement=file.createIfcAxis2Placement2D(
+                Location=file.createIfcCartesianPoint(alignment.ObjectPlacement.RelativePlacement.Location.Coordinates)
+            ),
+        )
+
+    # this commented out code is what you would do to add a geometric representation of the referent
+    # the example is a circle. a better way would be to pass a representation into the function
+    #    representation = file.create_entity(
+    #        name="IfcCircle",
+    #        position=file.createIfcAxis2Placement2D(Location=file.createIfcCartesianPoint(Coordinates=(0.0, 0.0)),
+    #        radius=1.0)
+    #    )
+
+    # create referent for the station
+    referent = file.createIfcReferent(
+        GlobalId=ifcopenshell.guid.new(),
+        OwnerHistory=None,
+        Name=name,
+        Description=None,
+        ObjectType=None,
+        ObjectPlacement=object_placement,
+        Representation=representation,
+        PredefinedType="POSITION",
+    )
+    pset_stationing = ifcopenshell.api.pset.add_pset(file, product=referent, name="Pset_Stationing")
+    ifcopenshell.api.pset.edit_pset(file, pset=pset_stationing, properties={"Station": station})
+
+    if len(referent.Positions) == 0:
+        rel_positions = file.createIfcRelPositions(
+            GlobalId=ifcopenshell.guid.new(),
+            RelatingPositioningElement=referent,
+            RelatedProducts=[
+                positioned_product,
+            ],
+        )
+    else:
+        referent.Positions[0].RelatedProducts += (positioned_product,)
+
+    return referent

src/ifcopenshell-python/ifcopenshell/api/alignment/add_stationing_referent.py

@@ -16,35 +16,35 @@
 # You should have received a copy of the GNU Lesser General Public License
 # along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
 
-import numpy as np
+from typing import Optional
 
 import ifcopenshell
 import ifcopenshell.api.alignment
 from ifcopenshell.api.alignment.update_fallback_position import update_fallback_position
 import ifcopenshell.api.pset
-import ifcopenshell.geom
 import ifcopenshell.guid
 import ifcopenshell.util.element
-import ifcopenshell.util.unit
-from ifcopenshell import entity_instance, ifcopenshell_wrapper
+from ifcopenshell import entity_instance
 
 
 def add_stationing_referent(
     file: ifcopenshell.file,
+    name: str,
     alignment: entity_instance,
     distance_along: float,
     station: float,
-    name: str,
-    positioned_product: entity_instance,
+    incoming_station: Optional[float] = None,
+    on_basis_curve: Optional[bool] = None,
 ) -> entity_instance:
     """
-    Adds an IfcReferent to the alignment with the Pset_Stationing property set.
+    Adds an IfcReferent to the alignment that defines the stationing system.
 
+    :param name: name to assign to IfcReferent.Name, typically a stringized version of the station value
     :param alignment: the alignment to receive the referent
     :param distance_along: distance along the alignment basis curve
     :param station: station value
-    :param name: name to assign to IfcReferent.Name, typically a stringized version of the station value
-    :param positioned_product: the product whose position is informed by the referent
+    :param incoming_station: station value of the incoming segment, only set to specify a station equation
+    :param on_basis_curve: whether the referent is positioned on the basis curve or the alignment curve, if None the function will default to the basis curve
     :return: referent
 
     Example:
@@ -52,14 +52,21 @@ def add_stationing_referent(
     .. code:: python
 
         alignment = model.by_type("IfcAlignment")[0]
-        ifcopenshell.api.alignment.add_stationing_referent(model,alignment=alignment,distance_along=0.0,station=100.0)
+        ifcopenshell.api.alignment.add_stationing_referent(model,name="1+00.0",alignment=alignment,distance_along=0.0,station=100.0)
     """
 
-    basis_curve = ifcopenshell.api.alignment.get_basis_curve(alignment)
+    if on_basis_curve is None:
+        on_basis_curve = True
+
+    curve = (
+        ifcopenshell.api.alignment.get_basis_curve(alignment)
+        if on_basis_curve
+        else ifcopenshell.api.alignment.get_curve(alignment)
+    )
 
     object_placement = None
     representation = None
-    if basis_curve and basis_curve.is_a("IfcCompositeCurve") and 0 < len(basis_curve.Segments):
+    if curve and curve.is_a("IfcCompositeCurve") and 0 < len(curve.Segments):
         object_placement = file.createIfcLinearPlacement(
             RelativePlacement=file.createIfcAxis2PlacementLinear(
                 Location=file.createIfcPointByDistanceExpression(
@@ -67,7 +74,7 @@ def add_stationing_referent(
                     OffsetLateral=None,
                     OffsetVertical=None,
                     OffsetLongitudinal=None,
-                    BasisCurve=basis_curve,
+                    BasisCurve=curve,
                 )
             ),
         )
@@ -100,8 +107,12 @@ def add_stationing_referent(
         Representation=representation,
         PredefinedType="STATION",
     )
+    properties = {"Station": station}
+    if incoming_station is not None:
+        properties["IncomingStation"] = incoming_station
+
     pset_stationing = ifcopenshell.api.pset.add_pset(file, product=referent, name="Pset_Stationing")
-    ifcopenshell.api.pset.edit_pset(file, pset=pset_stationing, properties={"Station": station})
+    ifcopenshell.api.pset.edit_pset(file, pset=pset_stationing, properties=properties)
 
     nest = ifcopenshell.api.alignment.get_referent_nest(file, alignment)
     if nest is None:
@@ -115,15 +126,4 @@ def add_stationing_referent(
         nest.RelatedObjects, key=lambda x: ifcopenshell.util.element.get_pset(x, name="Pset_Stationing", prop="Station")
     )
 
-    if len(referent.Positions) == 0:
-        rel_positions = file.createIfcRelPositions(
-            GlobalId=ifcopenshell.guid.new(),
-            RelatingPositioningElement=referent,
-            RelatedProducts=[
-                positioned_product,
-            ],
-        )
-    else:
-        referent.Positions[0].RelatedProducts += (positioned_product,)
-
     return referent

src/ifcopenshell-python/ifcopenshell/api/alignment/add_vertical_layout.py

@@ -51,18 +51,6 @@ def _move_vertical_layout_to_child_alignment(
     # aggregate the child alignment to the parent alignment
     ifcopenshell.api.aggregate.assign_object(file, products=[child_alignment], relating_object=parent_alignment)
 
-    # move all referents positioning segments of the vertical layout to the referent nest of the child alignment
-    child_referent_nest = ifcopenshell.api.alignment.get_referent_nest(file, child_alignment)
-    parent_referent_nest = ifcopenshell.api.alignment.get_referent_nest(file, parent_alignment)
-    for referent in parent_referent_nest.RelatedObjects:
-        for product in referent.Positions[0].RelatedProducts:
-            if product.is_a("IfcAlignmentSegment") and product.Nests[0].RelatingObject == vertical_layout:
-                # ifcopenshell.api.nest.change_nest(file,referent,child_alignment) - this doesn't work because referent is assigned to child_alignment.IsNestedBy[0].RelatedObjects
-                # and it needs to be assigned to child_alignment.IsNestedBy[1].RelatedObjects
-                # move the referent manually - unassign it and add it to the child alignment's referent nest
-                ifcopenshell.api.nest.unassign_object(file, [referent])
-                child_referent_nest.RelatedObjects += (referent,)
-
     # if the parent alignment has a representation, move the Axis/Curve3D represention to the child alignment
     base_curve = ifcopenshell.api.alignment.get_basis_curve(parent_alignment)
     if base_curve:

src/ifcopenshell-python/ifcopenshell/api/alignment/add_zero_length_segment.py

@@ -23,18 +23,8 @@ import ifcopenshell.api.alignment
 from ifcopenshell.api.alignment._get_segment_endpoint import _get_segment_endpoint
 from ifcopenshell.api.alignment._update_zero_length_segment_placement import _update_zero_length_segment_placement
 import ifcopenshell.api.nest
-import ifcopenshell.ifcopenshell_wrapper as wrapper
 import ifcopenshell.util.unit
 from ifcopenshell import entity_instance
-from ifcopenshell.api.alignment._get_segment_start_point_label import (
-    _get_segment_start_point_label,
-)
-from ifcopenshell.api.alignment._map_alignment_horizontal_segment import (
-    _map_alignment_horizontal_segment,
-)
-from ifcopenshell.api.alignment._map_alignment_vertical_segment import (
-    _map_alignment_vertical_segment,
-)
 from ifcopenshell.api.alignment._update_curve_segment_transition_code import (
     _update_curve_segment_transition_code,
 )

src/ifcopenshell-python/ifcopenshell/api/alignment/create.py

@@ -87,9 +87,7 @@ def create(
         _create_geometric_representation(file, alignment)
 
     referent_name = ifcopenshell.util.alignment.station_as_string(file, start_station)
-    referent = ifcopenshell.api.alignment.add_stationing_referent(
-        file, alignment, 0.0, start_station, referent_name, alignment
-    )
+    referent = ifcopenshell.api.alignment.add_stationing_referent(file, referent_name, alignment, 0.0, start_station)
 
     for layout in alignment_layouts:
         _add_zero_length_segment(file, layout)

src/ifcopenshell-python/ifcopenshell/api/alignment/create_as_polyline.py

@@ -141,7 +141,7 @@ def create_as_polyline(
 
     # define stationing
     name = ifcopenshell.util.alignment.station_as_string(file, start_station)
-    referent = ifcopenshell.api.alignment.add_stationing_referent(file, alignment, 0.0, start_station, name, alignment)
+    referent = ifcopenshell.api.alignment.add_stationing_referent(file, name, alignment, 0.0, start_station)
 
     # IFC 4.1.4.1.1 Alignment Aggregation To Project
     project = file.by_type("IfcProject")[0]

src/ifcopenshell-python/ifcopenshell/api/alignment/create_layout_segment.py

@@ -21,9 +21,7 @@ from typing import Union
 import numpy as np
 
 import ifcopenshell
-import ifcopenshell.api.alignment
-import ifcopenshell.geom
-from ifcopenshell import entity_instance, ifcopenshell_wrapper
+from ifcopenshell import entity_instance
 from ifcopenshell.api.alignment._add_segment_to_layout import _add_segment_to_layout
 
 

src/ifcopenshell-python/ifcopenshell/api/alignment/distance_along_from_station.py

@@ -16,23 +16,47 @@
 # You should have received a copy of the GNU Lesser General Public License
 # along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
 
+from typing import Optional
+
 import ifcopenshell
 import ifcopenshell.api.alignment
+import ifcopenshell.util.element
 from ifcopenshell import entity_instance
 
 
-def distance_along_from_station(file: ifcopenshell.file, alignment: entity_instance, station: float) -> float:
+def _distance_along_of_referent(referent: entity_instance) -> float:
+    placement = referent.ObjectPlacement
+    if placement.is_a("IfcLinearPlacement"):
+        return placement.RelativePlacement.Location.DistanceAlong.wrappedValue
+    # IfcLocalPlacement fallback (e.g. semantic-only alignment, or the placement could not yet
+    # be expressed relative to a basis curve) carries no DistanceAlong; it is only ever used for
+    # the starting referent, at distance 0.0.
+    return 0.0
+
+
+def distance_along_from_station(file: ifcopenshell.file, alignment: entity_instance, station: float) -> Optional[float]:
     """
     Given a station, returns the distance along the horizontal alignment.
 
     If the alignment does not have stationing defined with an IfcReferent, the start of the alignment is assumed
     to be at station 0.0. That is, the station is the distance along.
 
-    .. note:: The current implementation does not account for station equations and assumes stationing is increasing along the alignment.
+    Station equations (where Pset_Stationing.IncomingStation is set on a referent) are taken into account.
+    For each STATION referent nested to the alignment, DistanceAlong (D) and the outgoing station (S, i.e.
+    Pset_Stationing.Station) are read off, sorted by DistanceAlong. The requested station is located within
+    the segment defined by the last referent whose outgoing station is less than or equal to it, and the
+    distance along is computed as D + (station - S) for that referent.
+
+    If the station falls within a gap introduced by a forward (gap) station equation - that is, it was skipped
+    over by the equation - there is no distance along that corresponds to it, and None is returned.
+
+    Note that an overlap (backward) station equation causes a range of stations to correspond to two distinct
+    distances along the alignment, one on either side of the equation. This implementation returns the distance
+    along in the segment following the equation (i.e. the outgoing side).
 
     :param alignment: the alignment
     :param station: station value
-    :return: distance along the horizontal alignment
+    :return: distance along the horizontal alignment, or None if the station falls inside a station equation gap
 
     Example:
 
@@ -43,6 +67,36 @@ def distance_along_from_station(file: ifcopenshell.file, alignment: entity_insta
         print(dist_along) # 100.00
     """
 
-    start_station = ifcopenshell.api.alignment.get_alignment_start_station(file, alignment)
-    dist_along = station - start_station
-    return dist_along
+    referent_nest = ifcopenshell.api.alignment.get_referent_nest(file, alignment)
+    if referent_nest is None:
+        start_station = ifcopenshell.api.alignment.get_alignment_start_station(file, alignment)
+        return station - start_station
+
+    stations = [
+        (
+            _distance_along_of_referent(referent),
+            ifcopenshell.util.element.get_pset(referent, name="Pset_Stationing", prop="Station"),
+        )
+        for referent in referent_nest.RelatedObjects
+    ]
+    stations.sort(key=lambda entry: entry[0])
+
+    index = None
+    for i, (distance_along, outgoing_station) in enumerate(stations):
+        if outgoing_station <= station:
+            index = i
+
+    if index is None:
+        # station precedes the alignment's starting station; extrapolate from the first referent
+        distance_along, outgoing_station = stations[0]
+        return distance_along + (station - outgoing_station)
+
+    distance_along, outgoing_station = stations[index]
+
+    if index + 1 < len(stations):
+        next_distance_along, _ = stations[index + 1]
+        if station - outgoing_station > next_distance_along - distance_along:
+            # the station was skipped over by a forward (gap) station equation
+            return None
+
+    return distance_along + (station - outgoing_station)

src/ifcopenshell-python/ifcopenshell/api/alignment/get_curve_segment.py

@@ -16,7 +16,6 @@
 # You should have received a copy of the GNU Lesser General Public License
 # along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
 
-from collections.abc import Sequence
 
 from ifcopenshell import entity_instance
 

src/ifcopenshell-python/ifcopenshell/api/alignment/update_end_point.py

@@ -19,6 +19,7 @@
 import numpy as np
 
 import ifcopenshell
+import ifcopenshell.api.alignment
 import ifcopenshell.util.placement
 from ifcopenshell import entity_instance
 

src/ifcopenshell-python/ifcopenshell/api/alignment/update_fallback_position.py

@@ -16,8 +16,6 @@
 # You should have received a copy of the GNU Lesser General Public License
 # along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
 
-import numpy as np
-
 import ifcopenshell
 import ifcopenshell.util.placement
 from ifcopenshell import entity_instance
@@ -36,7 +34,7 @@ def update_fallback_position(file: ifcopenshell.file, lp: entity_instance):
     if not lp.CartesianPosition:
         lp.CartesianPosition = file.createIfcAxis2Placement3D(Location=file.createIfcCartesianPoint((0.0, 0.0, 0.0)))
 
-    p = np.array(ifcopenshell.util.placement.get_axis2placement(lp.RelativePlacement))
+    p = ifcopenshell.util.placement.get_local_placement(lp)
 
     x = float(p[0, 3])
     y = float(p[1, 3])

src/ifcopenshell-python/ifcopenshell/api/cost/assign_cost_item_quantity.py

@@ -117,7 +117,7 @@ def assign_cost_item_quantity(
         "products": products or [],
         "prop_name": prop_name,
         "formula": formula,
-        "ifc_class" : ifc_class
+        "ifc_class": ifc_class,
     }
     return usecase.execute()
 
@@ -134,7 +134,7 @@ class Usecase:
                 continue
             self.assign_cost_control(related_object=product, cost_item=self.settings["cost_item"])
             if self.settings["formula"]:
-                tree = ast.parse(self.settings["formula"], mode = "eval")
+                tree = ast.parse(self.settings["formula"], mode="eval")
                 collector = VariableExtractor()
                 collector.visit(tree)
                 variables = collector.variables
@@ -144,10 +144,10 @@ class Usecase:
                     value = getter(product, variable)
 
                 if value is None:
-                        print(
-                            f"WARNING: Variable '{variable}' in product '{product.Name}' "
-                            f"is missing (None). Check Pset/Qset or property name."
-                        )
+                    print(
+                        f"WARNING: Variable '{variable}' in product '{product.Name}' "
+                        f"is missing (None). Check Pset/Qset or property name."
+                    )
                 elif value == 0:
                     print(
                         f"WARNING: Variable '{variable}' in product '{product.Name}' "
@@ -159,7 +159,9 @@ class Usecase:
 
                 new_quantity = None
                 for quantity in self.quantities:
-                    if quantity.Formula == self.settings["formula"] and len(self.settings["products"]) == 1: #Todo improve it
+                    if (
+                        quantity.Formula == self.settings["formula"] and len(self.settings["products"]) == 1
+                    ):  # Todo improve it
                         new_quantity = quantity
                         self.settings["ifc_class"] = quantity.is_a()
                         continue
@@ -184,23 +186,23 @@ class Usecase:
             self.update_cost_item_count()
 
     def get_value_from_pset(
-            self,
-            product:ifcopenshell.entity_instance,
-            v: str,
+        self,
+        product: ifcopenshell.entity_instance,
+        v: str,
     ) -> float:
         pset_name = v.split(".")[0]
         pset = ifcopenshell.util.element.get_pset(product, pset_name)
         pset_property_name = v.split(".")[1]
-        return (pset or {}).get(pset_property_name,None)
+        return (pset or {}).get(pset_property_name, None)
 
     def get_value_from_qset(
-            self,
-            product:ifcopenshell.entity_instance,
-            v: str,
+        self,
+        product: ifcopenshell.entity_instance,
+        v: str,
     ) -> float:
-        qtos = ifcopenshell.util.element.get_psets(product, qtos_only = True)
+        qtos = ifcopenshell.util.element.get_psets(product, qtos_only=True)
         quantities = next(iter(qtos.values()), {})
-        return (quantities or {}).get(v,None)
+        return (quantities or {}).get(v, None)
 
     def assign_cost_control(
         self, related_object: ifcopenshell.entity_instance, cost_item: ifcopenshell.entity_instance
@@ -243,6 +245,7 @@ class Usecase:
                             count += 1
                 quantity[3] = count
 
+
 OPERATORS = {
     ast.Add: operator.add,
     ast.Sub: operator.sub,
@@ -252,18 +255,20 @@ OPERATORS = {
     ast.USub: operator.neg,
 }
 
+
 def build_full_name(node):
-    #used for variables with dots
+    # used for variables with dots
     parts = []
     while isinstance(node, ast.Attribute):
-            parts.append(node.attr)
-            node = node.value
+        parts.append(node.attr)
+        node = node.value
 
     if isinstance(node, ast.Name):
         parts.append(node.id)
 
     return ".".join(reversed(parts))
 
+
 class VariableExtractor(ast.NodeVisitor):
     def __init__(self):
         self.variables = set()
@@ -274,6 +279,7 @@ class VariableExtractor(ast.NodeVisitor):
     def visit_Attribute(self, node):
         self.variables.add(build_full_name(node))
 
+
 class FormulaEvaluator(ast.NodeVisitor):
     def __init__(self, values):
         self.values = values
@@ -281,7 +287,7 @@ class FormulaEvaluator(ast.NodeVisitor):
     def visit_BinOp(self, node):
         left = self.visit(node.left)
         right = self.visit(node.right)
-        return OPERATORS[type(node.op)](left, right)
+        return OPERATORS[type(node.op)](left, right)  # ty: ignore[too-many-positional-arguments]
 
     def visit_Name(self, node):
         return self.values[node.id]

src/ifcopenshell-python/ifcopenshell/entity_instance.py

@@ -642,16 +642,16 @@ class entity_instance:
         return_type: type[dict] = dict,
         ignore: Sequence[str] = (),
     ) -> dict[str, Any]:
-        """More perfomant version of `.get_info()` but with limited arguments values.\n
-        Method has exactly the same signature as `.get_info()` but it doesn't support getting information non-recursively.
-
-        Currently supported arguments values:
-            * recursive: `True` (will fail with default `False` value from `.get_info()`)
-            * return_type: `dict`
-            * ignore: `()` (empty tuple)
+        """More perfomant version of `.get_info()`.\n
+        Method has exactly the same signature as `.get_info()`, but the fast C++
+        path only implements ``recursive=True``, ``return_type=dict`` and
+        ``ignore=()``. Any other combination falls back to the pure Python
+        `.get_info()`, where no meaningful performance gain is possible anyway
+        as the cost is dominated by the recursive traversal.
         """
 
-        assert recursive
-        assert return_type is dict
-        assert len(ignore) == 0
-        return ifcopenshell_wrapper.get_info_cpp(self.wrapped_data, include_identifier)
+        if recursive and return_type is dict and not ignore:
+            return ifcopenshell_wrapper.get_info_cpp(self.wrapped_data, include_identifier)
+        return self.get_info(
+            include_identifier=include_identifier, recursive=recursive, return_type=return_type, ignore=ignore
+        )

src/ifcopenshell-python/ifcopenshell/express/bootstrap.py

@@ -221,8 +221,7 @@ for id in to_emit:
     statements.append("%s << %s" % (id, stmt))
 
 if __name__ == "__main__":
-    print(
-        r"""
+    print(r"""
 # This file is generated by IfcOpenShell ifcexpressparser bootstrap.py
 
 from __future__ import annotations
@@ -261,6 +260,4 @@ if __name__ == "__main__":
         mdl = importlib.import_module(output)
         mdl.Generator(m).emit()
     sys.stdout.write(m.schema.name)
-"""
-        % ("\n        ".join(statements))
-    )
+""" % ("\n        ".join(statements)))

src/ifcopenshell-python/ifcopenshell/express/rule_compiler.py

@@ -695,6 +695,7 @@ codegen_rule("MOD", lambda context: "%")
 codegen_rule("TRUE", lambda context: "True")
 codegen_rule("FALSE", lambda context: "False")
 
+
 def _dotted_name(node: ast.AST):
     """Return dotted name for Name/Attribute chains, else None."""
     if isinstance(node, ast.Name):
@@ -704,6 +705,7 @@ def _dotted_name(node: ast.AST):
         return f"{base}.{node.attr}" if base else node.attr
     return None
 
+
 class AttributeGetattrTransformer(ast.NodeTransformer):
     def visit_Attribute(self, node):
         parents = []
@@ -720,7 +722,7 @@ class AttributeGetattrTransformer(ast.NodeTransformer):
         if isinstance(node.ctx, ast.Store):
             return node
 
-        if _dotted_name(node) in ('ifcopenshell.create_entity', 'str.lower'):
+        if _dotted_name(node) in ("ifcopenshell.create_entity", "str.lower"):
             return node
 
         if node.attr.startswith("__"):

src/ifcopenshell-python/ifcopenshell/express/schema_class.py

@@ -363,24 +363,18 @@ class EarlyBoundCodeWriter:
             )
         )
 
-        self.statements[self.statements.index("{factory_placeholder}")] = (
-            """
+        self.statements[self.statements.index("{factory_placeholder}")] = """
 class %(schema_name)s_instance_factory : public IfcParse::instance_factory {
     virtual IfcUtil::IfcBaseClass* operator()(const IfcParse::declaration* decl, IfcEntityInstanceData&& data) const {
         %(instance_mapping)s
     }
 };
-"""
-            % locals()
-        )
+""" % locals()
 
         ""
-        self.statements[self.statements.index("{string_pool_placeholder}")] = (
-            """
+        self.statements[self.statements.index("{string_pool_placeholder}")] = """
 const std::string strings[] = {%s};
-"""
-            % ",".join(map(lambda s: '"%s"s' % s, self.strings))
-        )
+""" % ",".join(map(lambda s: '"%s"s' % s, self.strings))
 
     def __str__(self):
         return "\n".join(self.statements)

src/ifcopenshell-python/ifcopenshell/geom/app.py

@@ -145,8 +145,7 @@ class configuration:
             config.set(
                 "snippets",
                 "print all wall ids",
-                self.config_encode(
-                    """
+                self.config_encode("""
 ###########################################################################
 # A simple script that iterates over all walls in the current model       #
 # and prints their Globally unique IDs (GUIDS) to the console window      #
@@ -154,15 +153,13 @@ class configuration:
 
 for wall in model.by_type("IfcWall"):
     print ("wall with global id: "+str(wall.GlobalId))
-""".lstrip()
-                ),
+""".lstrip()),
             )
 
             config.set(
                 "snippets",
                 "print properties of current selection",
-                self.config_encode(
-                    """
+                self.config_encode("""
 ###########################################################################
 # A simple script that iterates over all IfcPropertySets of the currently #
 # selected object and prints them to the console                          #
@@ -180,8 +177,7 @@ if selection:
              for prop in relDefinesByProperties.RelatingPropertyDefinition.HasProperties:
                  print ("{:<20} :{}".format(prop.Name,prop.NominalValue.wrappedValue))
          print ("\\n")
-""".lstrip()
-                ),
+""".lstrip()),
             )
             with open(conf_file, "w") as configfile:
                 config.write(configfile)

src/ifcopenshell-python/ifcopenshell/ifcopenshell_wrapper.pyi

@@ -1697,10 +1697,16 @@ class uninitialized_tag: ...
 
 def arrange_polygons(settings, polygons): ...
 def clear_schemas(): ...
-def construct_iterator(geometry_library, settings, file, num_threads): ...
-def construct_iterator_with_include_exclude(geometry_library, settings, file, elems, include, num_threads): ...
-def construct_iterator_with_include_exclude_globalid(geometry_library, settings, file, elems, include, num_threads): ...
-def construct_iterator_with_include_exclude_id(geometry_library, settings, file, elems, include, num_threads): ...
+def construct_iterator(geometry_library, settings, file, num_threads, logger=...): ...
+def construct_iterator_with_include_exclude(
+    geometry_library, settings, file, elems, include, num_threads, logger=...
+): ...
+def construct_iterator_with_include_exclude_globalid(
+    geometry_library, settings, file, elems, include, num_threads, logger=...
+): ...
+def construct_iterator_with_include_exclude_id(
+    geometry_library, settings, file, elems, include, num_threads, logger=...
+): ...
 def convert_loop_to_function_item(loop): ...
 def create_box(*args): ...
 def create_epeck(*args): ...
@@ -1717,8 +1723,8 @@ def line_segments_to_polygons(s, eps, segments): ...
 def map_shape(settings, instance): ...
 def nary_union(sequence): ...
 def new_IfcBaseClass(schema_identifier: str, name: str) -> entity_instance: ...
-def open(fn: str, readonly: bool = False) -> file: ...
-def parse_ifcxml(filename): ...
+def open(fn: str, readonly: bool = False, logger=...) -> file: ...
+def parse_ifcxml(filename, logger=...): ...
 def polygons_to_svg(*args): ...
 def read(data): ...
 def register_schema(arg1): ...

src/ifcopenshell-python/ifcopenshell/util/alignment.py

@@ -56,7 +56,7 @@ def append_zero_length_segments(file: ifcopenshell.file) -> ifcopenshell.file:
     for alignment in alignments:
         layouts = ifcopenshell.api.alignment.get_alignment_layouts(alignment)
         for layout in layouts:
-            ifcopenshell.api.alignment.add_zero_length_segment(patched_file, layout, include_referent=False)
+            ifcopenshell.api.alignment.add_zero_length_segment(patched_file, layout)
             curve = ifcopenshell.api.alignment.get_layout_curve(layout)
             if curve:
                 ifcopenshell.api.alignment.add_zero_length_segment(patched_file, curve)

src/ifcopenshell-python/ifcopenshell/util/cost.py

@@ -355,8 +355,7 @@ def get_cost_rate(
 
 class CostValueUnserialiser:
     def parse(self, formula: str):
-        l = lark.Lark(
-            """start: formula
+        l = lark.Lark("""start: formula
                     formula: operand (operator operand)*
                     operand: value | category "(" formula ")"
                     value: NUMBER?
@@ -393,8 +392,7 @@ class CostValueUnserialiser:
                     NEWLINE: (CR? LF)+
 
                     %ignore WS // Disregard spaces in text
-                 """
-        )
+                 """)
         start = l.parse(formula)
         return self.get_formula(start.children[0])
 

src/ifcopenshell-python/ifcopenshell/util/element.py

@@ -1125,7 +1125,8 @@ def get_decomposition(element: ifcopenshell.entity_instance, is_recursive=True)
     """
     Retrieves all subelements of an element based on the spatial decomposition
     hierarchy. This includes all subspaces and elements contained in subspaces,
-    parts of an aggregate, all openings, and all fills of any openings.
+    parts of an aggregate, all openings, all fills of any openings, and any
+    surface features adhering to an element (IFC4.3 and above).
 
     :param element: The IFC element
     :return: The decomposition of the element
@@ -1161,6 +1162,10 @@ def get_decomposition(element: ifcopenshell.entity_instance, is_recursive=True)
             related = rel.RelatedObjects
             queue.extend(related)
             results.update(related)
+        for rel in getattr(element, "HasSurfaceFeatures", []):
+            related = rel.RelatedSurfaceFeatures
+            queue.extend(related)
+            results.update(related)
         if not is_recursive:
             break
     return results
@@ -1251,6 +1256,8 @@ def get_parent(
     - Nesting: components are attached to a host parent
     - Filling: the physical element fills an opening, such as a window filling a hole
     - Voiding: the opening voids another physical element, such as a hole in a wall
+    - Adherence: a surface feature adheres to a host element, such as a road
+      marking adhering to a road course (IFC4.3 and above)
 
     :param element: Any physical or spatial element in the tree
     :param ifc_class: Optionally filter the type of parent you're after. For
@@ -1270,6 +1277,7 @@ def get_parent(
         or get_nest(element)
         or get_filled_void(element)
         or get_voided_element(element)
+        or get_adhered_element(element)
     )
 
     if not ifc_class:
@@ -1321,6 +1329,28 @@ def get_voided_element(element: ifcopenshell.entity_instance) -> Union[ifcopensh
         return rel[0].RelatingBuildingElement
 
 
+def get_adhered_element(element: ifcopenshell.entity_instance) -> Union[ifcopenshell.entity_instance, None]:
+    """If the element is a surface feature, get the element it adheres to
+
+    In IFC4.3 an IfcSurfaceFeature (such as a road marking) adheres to a host
+    element through the IfcRelAdheresToElement relationship. This is a [1:1]
+    cardinality hierarchical relationship, in the same family as aggregation,
+    containment and nesting.
+
+    :param element: The IfcSurfaceFeature
+    :return: The host element that the surface feature adheres to
+
+    Example:
+
+    .. code:: python
+
+        marking = file.by_type("IfcSurfaceFeature")[0]
+        host = ifcopenshell.util.element.get_adhered_element(marking)
+    """
+    if rel := getattr(element, "AdheresToElement", None):
+        return rel[0].RelatingElement
+
+
 def get_aggregate(element: ifcopenshell.entity_instance) -> Union[ifcopenshell.entity_instance, None]:
     """
     Retrieves the aggregate parent of an element.
@@ -1415,6 +1445,29 @@ def get_contained(element: ifcopenshell.entity_instance) -> list[ifcopenshell.en
     return objects
 
 
+def get_surface_features(element: ifcopenshell.entity_instance) -> list[ifcopenshell.entity_instance]:
+    """Retrieves the surface features that adhere to an element.
+
+    In IFC4.3 an IfcSurfaceFeature (such as a road marking) adheres to a host
+    element through the IfcRelAdheresToElement relationship.
+
+    :param element: The IFC element
+    :return: The surface features adhering to the element
+
+    Example:
+
+    .. code:: python
+
+        element = file.by_type("IfcCourse")[0]
+        markings = ifcopenshell.util.element.get_surface_features(element)
+    """
+    objects: list[ifcopenshell.entity_instance] = []
+    if has_surface_features := getattr(element, "HasSurfaceFeatures", ()):
+        for rel in has_surface_features:
+            objects.extend(rel.RelatedSurfaceFeatures)
+    return objects
+
+
 def get_components(
     element: ifcopenshell.entity_instance, include_ports: bool = False
 ) -> list[ifcopenshell.entity_instance]:

src/ifcopenshell-python/ifcopenshell/util/selector.py

@@ -39,8 +39,7 @@ import ifcopenshell.util.shape
 import ifcopenshell.util.system
 import ifcopenshell.util.unit
 
-filter_elements_grammar = lark.Lark(
-    """start: filter_group
+filter_elements_grammar = lark.Lark("""start: filter_group
     filter_group: facet_list ("+" facet_list)*
     facet_list: facet ("," facet)*
 
@@ -111,11 +110,9 @@ filter_elements_grammar = lark.Lark(
     NEWLINE: (CR? LF)+
 
     %ignore WS // Disregard spaces in text
-"""
-)
+""")
 
-get_element_grammar = lark.Lark(
-    """start: keys
+get_element_grammar = lark.Lark("""start: keys
 
     keys: key ("." key)*
     key: quoted_string | regex_string | unquoted_string
@@ -130,11 +127,9 @@ get_element_grammar = lark.Lark(
     WS: /[ \\t\\f\\r\\n]/+
 
     %ignore WS // Disregard spaces in text
- """
-)
+ """)
 
-format_grammar = lark.Lark(
-    """start: expression
+format_grammar = lark.Lark("""start: expression
 
     ?expression: add_sub
     ?add_sub: mul_div
@@ -193,8 +188,7 @@ format_grammar = lark.Lark(
     NEWLINE: (CR? LF)+
 
     %ignore WS // Disregard spaces in text
-"""
-)
+""")
 
 
 class FormatTransformer(lark.Transformer):

src/ifcopenshell-python/ifcopenshell/util/unit.py

@@ -912,6 +912,13 @@ def convert_file_length_units(ifc_file: ifcopenshell.file, target_units: str = "
             new_value = convert_value(val)
             setattr(element, attr.name(), new_value)
 
+    # IfcGeometricRepresentationContext.Precision is typed as a plain IfcReal
+    # but is interpreted in the project length unit, so it must be scaled too.
+    # Subcontexts derive Precision from their parent and cannot be set.
+    for context in file_patched.by_type("IfcGeometricRepresentationContext", include_subtypes=False):
+        if context.Precision is not None:
+            context.Precision = convert_unit(context.Precision, old_length, new_length)
+
     has_map_unit = False
     if (
         ifc_file.schema == "IFC2X3"

src/ifcopenshell-python/test/api/alignment/test_add_positioning_referent.py

@@ -0,0 +1,100 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2025 Thomas Krijnen <thomas@aecgeeks.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+
+
+import ifcopenshell.api.alignment
+import ifcopenshell.api.context
+import ifcopenshell.api.unit
+import ifcopenshell.util.element
+
+
+def test_add_positioning_referent():
+    file = ifcopenshell.file(schema="IFC4X3")
+    project = file.createIfcProject(GlobalId=ifcopenshell.guid.new(), Name="Test")
+    length = ifcopenshell.api.unit.add_si_unit(file, unit_type="LENGTHUNIT")
+    ifcopenshell.api.unit.assign_unit(file, units=[length])
+    geometric_representation_context = ifcopenshell.api.context.add_context(file, context_type="Model")
+    axis_model_representation_subcontext = ifcopenshell.api.context.add_context(
+        file,
+        context_type="Model",
+        context_identifier="Axis",
+        target_view="MODEL_VIEW",
+        parent=geometric_representation_context,
+    )
+
+    alignment = ifcopenshell.api.alignment.create(file, "TestAlignment", start_station=2000.0)
+
+    horizontal_layout = ifcopenshell.api.alignment.get_horizontal_layout(alignment)
+    segment = ifcopenshell.api.alignment.get_layout_segments(horizontal_layout)[0]
+
+    referent = ifcopenshell.api.alignment.add_positioning_referent(
+        file, "P.C.", alignment, distance_along=0.0, station=2000.0, positioned_product=segment
+    )
+
+    assert referent.is_a("IfcReferent")
+    assert referent.PredefinedType == "POSITION"
+    assert referent.Name == "P.C."
+    assert ifcopenshell.util.element.get_pset(element=referent, name="Pset_Stationing")
+    assert ifcopenshell.util.element.get_pset(element=referent, name="Pset_Stationing", prop="Station") == 2000.0
+    assert referent.ObjectPlacement != None
+
+    assert len(referent.Positions) == 1
+    rel_positions = referent.Positions[0]
+    assert rel_positions.is_a("IfcRelPositions")
+    assert rel_positions.RelatingPositioningElement == referent
+    assert rel_positions.RelatedProducts == (segment,)
+
+
+def test_add_positioning_referent_creates_separate_referent_per_call():
+    file = ifcopenshell.file(schema="IFC4X3")
+    project = file.createIfcProject(GlobalId=ifcopenshell.guid.new(), Name="Test")
+    length = ifcopenshell.api.unit.add_si_unit(file, unit_type="LENGTHUNIT")
+    ifcopenshell.api.unit.assign_unit(file, units=[length])
+    geometric_representation_context = ifcopenshell.api.context.add_context(file, context_type="Model")
+    axis_model_representation_subcontext = ifcopenshell.api.context.add_context(
+        file,
+        context_type="Model",
+        context_identifier="Axis",
+        target_view="MODEL_VIEW",
+        parent=geometric_representation_context,
+    )
+
+    alignment = ifcopenshell.api.alignment.create(file, "TestAlignment", start_station=2000.0)
+
+    horizontal_layout = ifcopenshell.api.alignment.get_horizontal_layout(alignment)
+    segment = ifcopenshell.api.alignment.get_layout_segments(horizontal_layout)[0]
+
+    first_referent = ifcopenshell.api.alignment.add_positioning_referent(
+        file, "P.C.", alignment, distance_along=0.0, station=2000.0, positioned_product=segment
+    )
+
+    other_product = file.createIfcBuildingElementProxy(GlobalId=ifcopenshell.guid.new(), Name="Sign")
+    second_referent = ifcopenshell.api.alignment.add_positioning_referent(
+        file, "P.C.", alignment, distance_along=0.0, station=2000.0, positioned_product=other_product
+    )
+
+    # each call creates its own IfcReferent, each with its own IfcRelPositions to the product passed in
+    assert first_referent != second_referent
+    assert len(first_referent.Positions) == 1
+    assert first_referent.Positions[0].RelatedProducts == (segment,)
+    assert len(second_referent.Positions) == 1
+    assert second_referent.Positions[0].RelatedProducts == (other_product,)
+
+
+test_add_positioning_referent()
+test_add_positioning_referent_creates_separate_referent_per_call()

src/ifcopenshell-python/test/api/alignment/test_add_stationing_referent.py

@@ -0,0 +1,115 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2025 Thomas Krijnen <thomas@aecgeeks.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+
+
+import ifcopenshell.api.alignment
+import ifcopenshell.api.context
+import ifcopenshell.api.unit
+import ifcopenshell.util.element
+
+
+def _create_test_file():
+    file = ifcopenshell.file(schema="IFC4X3")
+    project = file.createIfcProject(GlobalId=ifcopenshell.guid.new(), Name="Test")
+    length = ifcopenshell.api.unit.add_si_unit(file, unit_type="LENGTHUNIT")
+    ifcopenshell.api.unit.assign_unit(file, units=[length])
+    geometric_representation_context = ifcopenshell.api.context.add_context(file, context_type="Model")
+    axis_model_representation_subcontext = ifcopenshell.api.context.add_context(
+        file,
+        context_type="Model",
+        context_identifier="Axis",
+        target_view="MODEL_VIEW",
+        parent=geometric_representation_context,
+    )
+    return file
+
+
+def _create_test_alignment_with_vertical(file):
+    # include_vertical=True so that get_curve() (IfcGradientCurve, on the "Axis" representation)
+    # and get_basis_curve() (IfcCompositeCurve, on the "FootPrint" representation) are different
+    # entities, letting the on_basis_curve option be observed.
+    alignment = ifcopenshell.api.alignment.create(file, "TestAlignment", include_vertical=True, start_station=0.0)
+    assert ifcopenshell.api.alignment.get_basis_curve(alignment).is_a("IfcCompositeCurve")
+    assert ifcopenshell.api.alignment.get_curve(alignment).is_a("IfcGradientCurve")
+    assert ifcopenshell.api.alignment.get_basis_curve(alignment) != ifcopenshell.api.alignment.get_curve(alignment)
+    return alignment
+
+
+def _assert_common_referent_asserts(referent, name, station):
+    assert referent.is_a("IfcReferent")
+    assert referent.PredefinedType == "STATION"
+    assert referent.Name == name
+    assert ifcopenshell.util.element.get_pset(element=referent, name="Pset_Stationing")
+    assert ifcopenshell.util.element.get_pset(element=referent, name="Pset_Stationing", prop="Station") == station
+    assert referent.ObjectPlacement != None
+
+
+def test_add_stationing_referent_on_basis_curve_none_defaults_to_basis_curve():
+    # on_basis_curve=None should behave the same as on_basis_curve=True
+    file = _create_test_file()
+    alignment = _create_test_alignment_with_vertical(file)
+
+    referent = ifcopenshell.api.alignment.add_stationing_referent(
+        file, "1+00.000", alignment, distance_along=100.0, station=100.0, on_basis_curve=None
+    )
+
+    _assert_common_referent_asserts(referent, "1+00.000", 100.0)
+
+    assert referent.ObjectPlacement.is_a("IfcLinearPlacement")
+    assert referent.ObjectPlacement.RelativePlacement.Location.BasisCurve == ifcopenshell.api.alignment.get_basis_curve(
+        alignment
+    )
+
+
+def test_add_stationing_referent_on_basis_curve_true():
+    file = _create_test_file()
+    alignment = _create_test_alignment_with_vertical(file)
+
+    referent = ifcopenshell.api.alignment.add_stationing_referent(
+        file, "1+00.000", alignment, distance_along=100.0, station=100.0, on_basis_curve=True
+    )
+
+    _assert_common_referent_asserts(referent, "1+00.000", 100.0)
+
+    assert referent.ObjectPlacement.is_a("IfcLinearPlacement")
+    assert referent.ObjectPlacement.RelativePlacement.Location.BasisCurve == ifcopenshell.api.alignment.get_basis_curve(
+        alignment
+    )
+
+
+def test_add_stationing_referent_on_basis_curve_false():
+    # with a vertical layout present, on_basis_curve=False positions the referent on the
+    # alignment curve (IfcGradientCurve) rather than on the basis curve (IfcCompositeCurve).
+    file = _create_test_file()
+    alignment = _create_test_alignment_with_vertical(file)
+
+    referent = ifcopenshell.api.alignment.add_stationing_referent(
+        file, "1+00.000", alignment, distance_along=100.0, station=100.0, on_basis_curve=False
+    )
+
+    _assert_common_referent_asserts(referent, "1+00.000", 100.0)
+
+    assert referent.ObjectPlacement.is_a("IfcLinearPlacement")
+    basis_curve = referent.ObjectPlacement.RelativePlacement.Location.BasisCurve
+    assert basis_curve == ifcopenshell.api.alignment.get_curve(alignment)
+    assert basis_curve != ifcopenshell.api.alignment.get_basis_curve(alignment)
+
+
+test_add_stationing_referent_on_basis_curve_none_defaults_to_basis_curve()
+test_add_stationing_referent_on_basis_curve_true()
+test_add_stationing_referent_on_basis_curve_false()

src/ifcopenshell-python/test/api/alignment/test_add_stationing_to_alignment.py

@@ -48,5 +48,26 @@ def test_add_stationing_to_alignment():
     assert ifcopenshell.util.element.get_pset(element=referent, name="Pset_Stationing", prop="Station") == 2000.0
     assert referent.ObjectPlacement != None
 
+    # add a station equation at 1000 distance along. this is station 3+000 in coming and 4+000 outgoing.
+    # this is a gap equation.
+    second_referent = ifcopenshell.api.alignment.add_stationing_referent(
+        file, "4+000.000", alignment, distance_along=1000.0, station=4000.0, incoming_station=3000.0
+    )
+
+    referent_nest = ifcopenshell.api.alignment.get_referent_nest(file, alignment)
+    assert len(referent_nest.RelatedObjects) == 2
+
+    assert second_referent == referent_nest.RelatedObjects[1]
+
+    assert second_referent.PredefinedType == "STATION"
+    assert second_referent.Name == "4+000.000"
+    assert ifcopenshell.util.element.get_pset(element=second_referent, name="Pset_Stationing")
+    assert ifcopenshell.util.element.get_pset(element=second_referent, name="Pset_Stationing", prop="Station") == 4000.0
+    assert (
+        ifcopenshell.util.element.get_pset(element=second_referent, name="Pset_Stationing", prop="IncomingStation")
+        == 3000.0
+    )
+    assert second_referent.ObjectPlacement != None
+
 
 test_add_stationing_to_alignment()

src/ifcopenshell-python/test/api/alignment/test_create_representation.py

@@ -21,9 +21,12 @@ import math
 
 import pytest
 import ifcopenshell
+import ifcopenshell.api.aggregate
 import ifcopenshell.api.alignment
+import ifcopenshell.api.context
+import ifcopenshell.api.spatial
 import ifcopenshell.api.unit
-import numpy as np
+import ifcopenshell.util.unit
 
 
 def test_create_representation():

src/ifcopenshell-python/test/api/alignment/test_distance_along_from_station.py

@@ -53,4 +53,56 @@ def test_distance_along_from_station():
     assert ifcopenshell.api.alignment.distance_along_from_station(file, alignment, 17525.36) == pytest.approx(7525.36)
 
 
+def test_distance_along_from_station_with_station_equations():
+    # Reproduces the worked example from the IFC Alignment Geometry Implementation Guide, chapter 9.2.6:
+    # a gap equation (P3: incoming 14+00.00, outgoing 17+00.00) and an overlap equation
+    # (P4: incoming 19+00.00, outgoing 18+50.00).
+    file = ifcopenshell.file(schema="IFC4X3")
+    project = file.createIfcProject(GlobalId=ifcopenshell.guid.new(), Name="Test")
+    length = ifcopenshell.api.unit.add_conversion_based_unit(file, name="foot")
+    ifcopenshell.api.unit.assign_unit(file, units=[length])
+    geometric_representation_context = ifcopenshell.api.context.add_context(file, context_type="Model")
+    axis_model_representation_subcontext = ifcopenshell.api.context.add_context(
+        file,
+        context_type="Model",
+        context_identifier="Axis",
+        target_view="MODEL_VIEW",
+        parent=geometric_representation_context,
+    )
+
+    coordinates = [(500.0, 2500.0), (3340.0, 660.0), (4340.0, 5000.0), (7600.0, 4560.0), (8480.0, 2010.0)]
+    radii = [(1000.0), (1250.0), (950.0)]
+    vpoints = [(0.0, 100.0), (2000.0, 135.0), (5000.0, 105.0), (7400.0, 153.0), (9800.0, 105.0), (12800.0, 90.0)]
+    lengths = [(1600.0), (1200.0), (2000.0), (800.0)]
+
+    alignment = ifcopenshell.api.alignment.create_by_pi_method(
+        file, "TestAlignment", coordinates, radii, vpoints, lengths, start_station=1000.0
+    )
+
+    ifcopenshell.api.alignment.add_stationing_referent(
+        file, "P3", alignment, distance_along=400.0, station=1700.0, incoming_station=1400.0
+    )
+    ifcopenshell.api.alignment.add_stationing_referent(
+        file, "P4", alignment, distance_along=600.0, station=1850.0, incoming_station=1900.0
+    )
+
+    distance_along_from_station = ifcopenshell.api.alignment.distance_along_from_station
+
+    # between P2 and P3: Sta. 13+00.00
+    assert distance_along_from_station(file, alignment, 1300.0) == pytest.approx(300.0)
+
+    # between P3 and P4: Sta. 18+00.00
+    assert distance_along_from_station(file, alignment, 1800.0) == pytest.approx(500.0)
+
+    # between P4 and P5: Sta. 19+25.00
+    assert distance_along_from_station(file, alignment, 1925.0) == pytest.approx(675.0)
+
+    # Sta. 15+00.00 falls inside the gap opened by the equation at P3 and has no corresponding distance along
+    assert distance_along_from_station(file, alignment, 1500.0) is None
+
+    # Sta. 18+75.00 falls inside the overlap zone at P4; the post-equation (outgoing) match is returned
+    assert distance_along_from_station(file, alignment, 1875.0) == pytest.approx(625.0)
+
+
 test_distance_along_from_station()
+test_distance_along_from_station_with_station_equations()

src/ifcopenshell-python/test/test_entity_instance.py

@@ -64,3 +64,14 @@ class TestGetInfo2(test.bootstrap.IFC4):
             "Outer": {"CfsFaces": None, "type": "IfcClosedShell"},
             "type": "IfcFacetedBrep",
         }
+
+    def test_unsupported_arguments_fall_back_to_get_info(self):
+        # Regression test for #4270: get_info_2 raised a bare AssertionError
+        # when called with its own default arguments (recursive=False) or any
+        # other combination the C++ fast path does not implement. It must
+        # delegate to get_info instead of crashing.
+        brep = self.file.create_entity("IfcFacetedBrep")
+        shell = self.file.create_entity("IfcClosedShell")
+        brep.Outer = shell
+        assert brep.get_info_2() == brep.get_info()
+        assert brep.get_info_2(recursive=True, ignore=("Outer",)) == brep.get_info(recursive=True, ignore=("Outer",))

src/ifcopenshell-python/test/test_parse.py

@@ -1,5 +1,6 @@
 import ifcopenshell
 
+
 def test_skip_over_non_entity_instance():
     data = """
 ISO-10303-21;

src/ifcopenshell-python/test/test_rules.py

@@ -46,4 +46,4 @@ def test_file(filename):
 
 
 if __name__ == "__main__":
-    pytest.main(["-sx", __file__, '--import-mode=importlib'])
+    pytest.main(["-sx", __file__, "--import-mode=importlib"])

src/ifcopenshell-python/test/util/test_unit.py

@@ -19,6 +19,7 @@
 from math import pi
 
 import numpy as np
+import pytest
 
 import ifcopenshell.api.context
 import ifcopenshell.api.georeference
@@ -258,6 +259,23 @@ class TestConvertFileLengthUnits(test.bootstrap.IFC2X3):
         assert max(i.id() for i in output) == len(output.wrapped_data.entity_names()) + 1
         assert subject.get_full_unit_name(subject.get_project_unit(output, "LENGTHUNIT")) == "METRE"
 
+    def test_precision_conversion(self):
+        # Regression test for #6127: IfcGeometricRepresentationContext.Precision
+        # is typed IfcReal but interpreted in the project length unit, so it must
+        # be scaled along with the length measures.
+        ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcProject")
+        unit = ifcopenshell.api.unit.add_si_unit(self.file, unit_type="LENGTHUNIT", prefix="MILLI")
+        ifcopenshell.api.unit.assign_unit(self.file, units=[unit])
+        context = ifcopenshell.api.context.add_context(self.file, context_type="Model")
+        context.Precision = 0.01
+        # Subcontexts derive Precision from the parent and must be left alone.
+        ifcopenshell.api.context.add_context(
+            self.file, context_type="Model", context_identifier="Body", target_view="MODEL_VIEW", parent=context
+        )
+        output = subject.convert_file_length_units(self.file, target_units="METER")
+        new_context = output.by_type("IfcGeometricRepresentationContext", include_subtypes=False)[0]
+        assert new_context.Precision == pytest.approx(0.00001)
+
     def test_attribute_conversion(self):
         ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcProject")
         unit = ifcopenshell.api.unit.add_si_unit(self.file, unit_type="LENGTHUNIT", prefix="MILLI")

src/ifcparse/IfcParse.cpp

@@ -39,6 +39,7 @@
 #include <stdlib.h>
 #include <string>
 #include <iomanip>
+#include <charconv>
 
 #ifdef USE_MMAP
 #include <boost/filesystem/path.hpp>
@@ -449,7 +450,14 @@ const std::string& TokenFunc::asStringRef(const Token& token) {
     }
     std::string& str = token.lexer->GetTempString();
     token.lexer->TokenString(token.startPos, str);
-    if ((isString(token) || isEnumeration(token) || isBinary(token)) && !str.empty()) {
+    // A well-formed string/enumeration/binary token has both delimiters (e.g.
+    // '...', .XXX., "...."), so at least two characters. Malformed input from a
+    // fuzzer can produce a single-character token (e.g. a bare '.' left by
+    // ".)" instead of ".PHYSICAL."); stripping both ends would then erase past
+    // the end of an already-empty string, which is undefined behaviour and
+    // aborts under hardened standard libraries (_GLIBCXX_ASSERTIONS). Require
+    // two characters before stripping. See #5683.
+    if ((isString(token) || isEnumeration(token) || isBinary(token)) && str.size() >= 2) {
         //remove start+end characters in-place
         str.erase(str.end() - 1);
         str.erase(str.begin());
@@ -746,25 +754,29 @@ namespace {
         // the output of the C++ ostream formatting operation.
         // REAL = [ SIGN ] DIGIT { DIGIT } "." { DIGIT } [ "E" [ SIGN ] DIGIT { DIGIT } ] .
         static std::string format_double(const double& d) {
-            std::ostringstream oss;
-            oss.imbue(std::locale::classic());
-            oss << std::setprecision(std::numeric_limits<double>::max_digits10) << d;
-            const std::string str = oss.str();
-            oss.str("");
+            // Use the shortest representation that round-trips exactly (like
+            // Python's repr) instead of max_digits10. max_digits10 padded clean
+            // values with noise digits (0.0174532925199433 -> 0.017453292519943299),
+            // which rewrote every REAL and produced huge diffs when a file was
+            // re-saved. See #7696.
+            // std::to_chars is locale-independent, so no ostringstream/imbue is
+            // needed here.
+            char buf[64];
+            const auto res = std::to_chars(buf, buf + sizeof(buf), d);
+            const std::string str(buf, res.ptr);
             std::string::size_type e = str.find('e');
             if (e == std::string::npos) {
                 e = str.find('E');
             }
-            const std::string mantissa = str.substr(0, e);
-            oss << mantissa;
-            if (mantissa.find('.') == std::string::npos) {
-                oss << ".";
+            std::string result = str.substr(0, e);
+            if (result.find('.') == std::string::npos) {
+                result += '.';
             }
             if (e != std::string::npos) {
-                oss << "E";
-                oss << str.substr(e + 1);
+                result += 'E';
+                result += str.substr(e + 1);
             }
-            return oss.str();
+            return result;
         }
 
         static std::string format_binary(const boost::dynamic_bitset<>& b) {

src/ifcparse/IfcUtil.cpp

@@ -187,6 +187,15 @@ void IfcUtil::sanitate_material_name(std::string& str) {
 }
 
 void IfcUtil::escape_xml(std::string& str) {
+    // Strip characters that are illegal in XML 1.0. Control characters other
+    // than tab (0x09), newline (0x0A) and carriage return (0x0D) are not valid
+    // XML 1.0 characters and cannot even be represented as numeric character
+    // references, so they would otherwise make the serialized XML/SVG output
+    // non-well-formed. Bytes belonging to a valid UTF-8 multibyte sequence are
+    // always >= 0x80, so filtering on the low control range leaves them intact.
+    str.erase(std::remove_if(str.begin(), str.end(), [](unsigned char c) {
+        return c < 0x20 && c != '\t' && c != '\n' && c != '\r';
+    }), str.end());
     boost::replace_all(str, "&", "&amp;");
     boost::replace_all(str, "\"", "&quot;");
     boost::replace_all(str, "'", "&apos;");
@@ -353,6 +362,17 @@ IFC_PARSE_API bool IfcUtil::path::rename_file(const std::string& old_filename, c
     return success;
 }
 
+IFC_PARSE_API bool IfcUtil::path::atomic_rename_file(const std::string& old_filename, const std::string& new_filename) {
+    std::wstring old_filename_w = from_utf8(old_filename);
+    std::wstring new_filename_w = from_utf8(new_filename);
+    // MOVEFILE_REPLACE_EXISTING makes the replace atomic on NTFS (no unlink
+    // of the destination first). MOVEFILE_WRITE_THROUGH waits until the move
+    // is flushed to disk before returning.
+    const bool success = !!MoveFileExW(old_filename_w.c_str(), new_filename_w.c_str(),
+        MOVEFILE_REPLACE_EXISTING | MOVEFILE_WRITE_THROUGH);
+    return success;
+}
+
 IFC_PARSE_API bool IfcUtil::path::delete_file(const std::string& filename) {
     std::wstring filename_w = from_utf8(filename);
     const bool success = !!DeleteFileW(filename_w.c_str());
@@ -368,6 +388,12 @@ IFC_PARSE_API bool IfcUtil::path::rename_file(const std::string& old_filename, c
     return std::rename(old_filename.c_str(), new_filename.c_str()) == 0;
 }
 
+IFC_PARSE_API bool IfcUtil::path::atomic_rename_file(const std::string& old_filename, const std::string& new_filename) {
+    // POSIX rename() atomically replaces an existing destination on the same
+    // filesystem, so there is no window in which new_filename is missing.
+    return std::rename(old_filename.c_str(), new_filename.c_str()) == 0;
+}
+
 IFC_PARSE_API bool IfcUtil::path::delete_file(const std::string& filename) {
     return std::remove(filename.c_str()) != 0;
 }

src/ifcparse/buildinfo.cpp

@@ -30,6 +30,10 @@
 
 #if defined(IFCOPENSHELL_BRANCH) && defined(IFCOPENSHELL_COMMIT)
 const char *IFCOPENSHELL_VERSION = STRINGIFY(IFCOPENSHELL_BRANCH) "-" STRINGIFY(IFCOPENSHELL_COMMIT);
+#elif defined(IFCOPENSHELL_VERSION_STRING)
+// Set from CMake's RELEASE_VERSION (the repository VERSION file) so a release
+// build without commit-sha info still reports the correct version. See #8164.
+const char *IFCOPENSHELL_VERSION = STRINGIFY(IFCOPENSHELL_VERSION_STRING);
 #else
 const char *IFCOPENSHELL_VERSION = "0.8.0";
 #endif

src/ifcparse/utils.h

@@ -37,6 +37,13 @@ namespace path {
 IFC_PARSE_API bool delete_file(const std::string& filename);
 IFC_PARSE_API bool rename_file(const std::string& old_filename, const std::string& new_filename);
 
+/// Atomically renames old_filename onto new_filename, replacing an existing
+/// destination in a single filesystem operation. Unlike rename_file(), the
+/// destination is never unlinked before the rename, so an interruption can
+/// never leave the destination missing. This requires both paths to live on
+/// the same filesystem. Returns true on success.
+IFC_PARSE_API bool atomic_rename_file(const std::string& old_filename, const std::string& new_filename);
+
 #if defined(_MSC_VER) && defined(_UNICODE)
 
 /// Uses windows.h string conversion functions

src/ifcpatch/ifcpatch/recipes/ExtractElements.py

@@ -110,8 +110,8 @@ class Patcher(ifcpatch.BasePatcher):
             pass
         if element.is_a("IfcProject"):
             proj = self.new.add(element)
-            for ctx in element.RepresentationContexts:
-                for coop in getattr(ctx, 'HasCoordinateOperation', ()):
+            for ctx in element.RepresentationContexts or ():
+                for coop in getattr(ctx, "HasCoordinateOperation", ()):
                     self.new.add(coop)
             return proj
         return ifcopenshell.api.project.append_asset(

src/ifcpatch/test/test_DowngradeIndexedPolyCurve.py

@@ -33,9 +33,7 @@ class TestDowngradeIndexedPolyCurve(test.bootstrap.IFC4):
             Points=point_list,
             Segments=segments,
         )
-        self.file.create_entity(
-            "IfcArbitraryClosedProfileDef", ProfileType="AREA", OuterCurve=curve
-        )
+        self.file.create_entity("IfcArbitraryClosedProfileDef", ProfileType="AREA", OuterCurve=curve)
         return curve
 
     def test_run_without_segments(self):
@@ -80,9 +78,7 @@ class TestDowngradeIndexedPolyCurve(test.bootstrap.IFC4):
             Points=point_list,
             Segments=[self.file.createIfcLineIndex((1, 2, 3, 4, 1))],
         )
-        self.file.create_entity(
-            "IfcArbitraryClosedProfileDef", ProfileType="AREA", OuterCurve=curve
-        )
+        self.file.create_entity("IfcArbitraryClosedProfileDef", ProfileType="AREA", OuterCurve=curve)
         ifcpatch.execute(
             {"input": "input.ifc", "file": self.file, "recipe": "DowngradeIndexedPolyCurve", "arguments": []}
         )
@@ -110,9 +106,7 @@ class TestDowngradeIndexedPolyCurve(test.bootstrap.IFC4):
                 self.file.createIfcLineIndex((3, 4)),
             ],
         )
-        self.file.create_entity(
-            "IfcArbitraryClosedProfileDef", ProfileType="AREA", OuterCurve=curve
-        )
+        self.file.create_entity("IfcArbitraryClosedProfileDef", ProfileType="AREA", OuterCurve=curve)
         ifcpatch.execute(
             {"input": "input.ifc", "file": self.file, "recipe": "DowngradeIndexedPolyCurve", "arguments": []}
         )

src/ifcpatch/test/test_ExtractElements.py

@@ -21,10 +21,12 @@ import os
 import ifcopenshell
 import ifcopenshell.api.aggregate
 import ifcopenshell.api.context
+import ifcopenshell.api.geometry
 import ifcopenshell.api.georeference
 import ifcopenshell.api.root
 import ifcopenshell.api.spatial
 import ifcopenshell.util.element
+import numpy
 import pytest
 
 import ifcpatch
@@ -96,7 +98,10 @@ class TestExtractElements(test.bootstrap.IFC4):
             self.file,
             coordinate_operation={"Eastings": 100000.0, "Northings": 200000.0},
         )
-        ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcWall")
+        wall = ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcWall")
+        matrix = numpy.eye(4)
+        matrix[:3, 3] = [5.0, 10.0, 2.0]
+        ifcopenshell.api.geometry.edit_object_placement(self.file, product=wall, matrix=matrix)
 
         output = ifcpatch.execute({"file": self.file, "recipe": "ExtractElements", "arguments": ["IfcWall"]})
 
@@ -105,6 +110,11 @@ class TestExtractElements(test.bootstrap.IFC4):
         conversion = output.by_type("IfcMapConversion")[0]
         assert conversion.Eastings == 100000.0
         assert conversion.Northings == 200000.0
+        # Placements must be copied verbatim: extraction must not bake map
+        # coordinates (or any other georeferencing transform) into the local
+        # placements of the extracted elements.
+        wall_new = output.by_type("IfcWall")[0]
+        assert wall_new.ObjectPlacement.RelativePlacement.Location.Coordinates == (5.0, 10.0, 2.0)
 
     @pytest.mark.skipif(
         "IFC4X3" not in ifcopenshell.ifcopenshell_wrapper.schema_names(),

src/ifcwrap/IfcGeomWrapper.i

@@ -977,12 +977,14 @@ struct ShapeRTTI : public boost::static_visitor<PyObject*>
 			if (item == nullptr) {
 				throw IfcParse::IfcException("Failed to convert placement");
 			}
+			/*
             if (st.get<ifcopenshell::geometry::settings::ConvertBackUnits>().get()) {
                 // we pass the settings to the Transformation object, but access the data just offloads to the
                 // generic cartesian_base<Matrix4> so there's no time to apply the settings to the translation part.
                 item = ifcopenshell::geometry::taxonomy::matrix4::ptr(item->clone_());
                 item->components().col(3).head<3>() /= kernel.settings().get<ifcopenshell::geometry::settings::LengthUnit>().get();
             }
+			*/
 			return new IfcGeom::Transformation(kernel.settings(), item);
 		} else {
 			if (!representation) {

src/ifcwrap/IfcParseWrapper.i

@@ -117,10 +117,51 @@ PyObject* get_feature(const std::string& x) {
 
 %{
 
+#include <fstream>
+#include <random>
+
 static const std::string& helper_fn_declaration_get_name(const IfcParse::declaration* decl) {
 	return decl->name();
 }
 
+// Atomic IFC/STEP write (issue #4797): serialize to a temporary file next to
+// the destination, then atomically rename it onto the destination. If the
+// process is interrupted mid-write, the destination is never truncated or
+// left with dangling STEP references; at most a stray temp file remains, which
+// the caller can safely ignore. Keeping the temp in the same directory means
+// the rename stays on a single filesystem and is therefore atomic. The temp
+// path never leaks into the FILE_NAME header, which is derived from the model
+// header, not the output path.
+template <typename T>
+static void helper_fn_atomic_write(T& file_obj, const std::string& fn) {
+	std::random_device rd;
+	const std::string temp_fn = fn + "." + std::to_string(rd()) + ".tmp";
+	{
+		// Same open mode as a plain write so the bytes are identical.
+		std::ofstream f(IfcUtil::path::from_utf8(temp_fn).c_str());
+		if (!f.good()) {
+			// The temp file could not be created (e.g. directory not
+			// writable). Nothing was touched; report as a normal write error.
+			throw std::runtime_error("Failed to write to path: '" + fn + "', check folder and file permissions.");
+		}
+		f << file_obj;
+		f.flush();
+		if (!f.good()) {
+			// Serialization failed (e.g. disk full). Clean up the partial temp
+			// and abort. The existing destination is left intact.
+			f.close();
+			IfcUtil::path::delete_file(temp_fn);
+			throw std::runtime_error("Failed to write to path: '" + fn + "', the file may be incomplete.");
+		}
+		// The ofstream destructor at the end of this scope closes the stream.
+		// On Windows the file must be closed before it can be renamed.
+	}
+	if (!IfcUtil::path::atomic_rename_file(temp_fn, fn)) {
+		IfcUtil::path::delete_file(temp_fn);
+		throw std::runtime_error("Failed to write to path: '" + fn + "', could not replace the existing file.");
+	}
+}
+
 static IfcUtil::ArgumentType helper_fn_attribute_type(const IfcUtil::IfcBaseClass* inst, unsigned i) {
 	const IfcParse::parameter_type* pt = 0;
 	if (inst->declaration().as_entity()) {
@@ -219,11 +260,10 @@ private:
 	}
 
 	void write(const std::string& fn) {
-		std::ofstream f(IfcUtil::path::from_utf8(fn).c_str());
-		if (!f.good()) {
-			throw std::runtime_error("Failed to write to path: '" + fn + "', check folder and file permissions.");
-		}
-		f << (*$self);
+		// Atomic write: serialize to a temp file next to the target, then
+		// atomically rename it into place, so an interrupted write can never
+		// corrupt the destination (issue #4797).
+		helper_fn_atomic_write(*$self, fn);
 	}
 
 	std::string to_string() {

src/ifcwrap/utils/type_conversion.i

@@ -34,9 +34,19 @@
 		if (PySequence_Size(aggregate) == -1) return false;
 		for(Py_ssize_t i = 0; i < PySequence_Size(aggregate); ++i) {
 			PyObject* element = PySequence_GetItem(aggregate, i);
-			// This is equivalent to the PyFloat_CheckExact macro. This means
-			// that direct instances of int, float, str, etc. need to be used.
-			bool b = element->ob_type == type_obj;
+			// Accept the exact type or, for the numeric types, a subclass such
+			// as a numpy scalar (numpy.float64 subclasses float), so that numpy
+			// arrays can be assigned. The REAL vs INTEGER distinction is kept: a
+			// float is not accepted where an int is expected and vice versa, and
+			// bool (a subclass of int) is still rejected for INTEGER. See #5873.
+			bool b;
+			if (type_obj == static_cast<void*>(&PyFloat_Type)) {
+				b = PyFloat_Check(element);
+			} else if (type_obj == static_cast<void*>(&PyLong_Type)) {
+				b = PyLong_Check(element) && !PyBool_Check(element);
+			} else {
+				b = element->ob_type == type_obj;
+			}
 			Py_DECREF(element);
 			if (!b) {
 				return false;