Fix anchor click, undo, layer regen, and ForcePerpendicularToFace for layer anchors

- ClickNearestDimensionAnchor: scan all selected objects instead of active
  object so clicking a green dot doesn't lose to the underlying IFC geometry
- GizmoAnchorHandle: remove draw_select entirely (any entry in the select
  buffer causes Blender's gizmo system to consume clicks); keep purely visual
- Scale anchor dots to scale_basis = 0.2
- Fix ReferenceError in decoration.py draw loop after undo by catching
  ReferenceError and resetting DecoratorData.is_loaded
- SetDimensionAnchor: inherit tool.Ifc.Operator so IFC pset writes are
  tracked for undo; finish the modal after each face write so each anchor
  gets its own undo step
- Fix ReferenceError in _modal after undo when annotation RNA is freed
- handler.py: add regenerate_dims_for_layer; call it from
  EditMaterialSetItem._execute so dimensions update when layer thickness changes
- regenerate_dimension.py: fix ForcePerpendicularToFace for LAYER_BOUNDARY
  anchors by deriving the thickness-axis normal from LayerSetDirection
  (AXIS2→Y, AXIS1→X, AXIS3→Z) instead of requiring a stored normal_local

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

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

@@ -215,9 +215,7 @@ def register():
     kc = wm.keyconfigs.addon
     if kc:
         km = kc.keymaps.new(name="3D View", space_type="VIEW_3D")
-        kmi = km.keymap_items.new(
-            "bim.click_nearest_dimension_anchor", "LEFTMOUSE", "PRESS"
-        )
+        kmi = km.keymap_items.new("bim.click_nearest_dimension_anchor", "LEFTMOUSE", "PRESS")
         _keymaps.append((km, kmi))
 
 

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

@@ -2146,4 +2146,8 @@ class DecorationsHandler:
 
         object_decorators = DecoratorData.data.get("object_decorators", [])
         for obj, decorator in object_decorators:
-            decorator.decorate(context, obj)
+            try:
+                decorator.decorate(context, obj)
+            except ReferenceError:
+                DecoratorData.is_loaded = False
+                break

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

@@ -2636,44 +2636,25 @@ class ExtrusionWidget(types.GizmoGroup):
 
 
 class GizmoAnchorHandle(bpy.types.Gizmo):
-    """Dot gizmo positioned at one vertex of a parametric dimension curve.
+    """Visual-only dot at a parametric dimension vertex.
 
-    Clicking it invokes ``bim.set_dimension_anchor`` pre-scoped to that vertex
-    index, skipping the manual vertex-pick phase of the operator.
+    No draw_select/invoke — any draw_select entry puts the gizmo in Blender's
+    select buffer, which causes the gizmo system to consume the click even
+    without an explicit invoke.  All click handling is done by the
+    bim.click_nearest_dimension_anchor keymap operator.
     """
 
     bl_idname = "BIM_GT_anchor_handle"
 
-    __slots__ = ("anchor_index", "custom_shape", "custom_shape_select")
+    __slots__ = ("anchor_index", "custom_shape")
 
     def setup(self):
         self.anchor_index = 0
         self.custom_shape = self.new_custom_shape(type="TRIS", verts=X3DISC)
-        # 4× scaled version used only for hit-detection — bigger target, same visual size.
-        _sel = tuple((x * 4.0, y * 4.0, z) for x, y, z in X3DISC)
-        self.custom_shape_select = self.new_custom_shape(type="TRIS", verts=_sel)
 
     def draw(self, context):
         self.draw_custom_shape(self.custom_shape)
 
-    def draw_select(self, context, select_id):
-        self.draw_custom_shape(self.custom_shape_select, select_id=select_id)
-
-    def invoke(self, context, event):
-        return {"RUNNING_MODAL"}
-
-    def modal(self, context, event, tweak):
-        anchor_index = self.anchor_index
-
-        def _launch():
-            try:
-                bpy.ops.bim.set_dimension_anchor("INVOKE_DEFAULT", anchor_index=anchor_index)
-            except Exception as e:
-                print(f"[DimensionAnchorWidget] {e}")
-            return None
-
-        bpy.app.timers.register(_launch, first_interval=0.0)
-        return {"FINISHED"}
 
 
 class DimensionAnchorWidget(types.GizmoGroup):
@@ -2697,12 +2678,22 @@ class DimensionAnchorWidget(types.GizmoGroup):
     def poll(cls, context: bpy.types.Context) -> bool:
         if not tool.Ifc.get():
             return False
-        # Stay visible while SetDimensionAnchor is running (active obj may be a temp element).
+        # Stay visible while SetDimensionAnchor is running (active obj may temporarily
+        # be an IFC element in the face-picking phase rather than the annotation).
         if _active_anchor_idx >= 0 and _editing_annotation_obj is not None:
-            return True
+            active = context.active_object
+            if active is _editing_annotation_obj:
+                return True  # annotation still active
+            if active is not None and tool.Ifc.get_entity(active) is not None:
+                return True  # face-picking phase: active obj is a target element
+            # Active object is None or a non-IFC object — the modal ended without
+            # calling set_active_anchor(-1).  Reset stale state and fall through.
+            set_active_anchor(-1)
         obj = context.active_object
         if not obj or obj.type != "CURVE":
             return False
+        if not obj.select_get():
+            return False
         element = tool.Ifc.get_entity(obj)
         if not element or not element.is_a("IfcAnnotation"):
             return False
@@ -2716,8 +2707,7 @@ class DimensionAnchorWidget(types.GizmoGroup):
         self._handles: list = []
         for _ in range(self._MAX_ANCHORS):
             gz = self.gizmos.new("BIM_GT_anchor_handle")
-            gz.scale_basis = 0.18
-            gz.select_bias = -32.0
+            gz.scale_basis = 0.2
             gz.use_draw_modal = True
             gz.hide = True
             self._handles.append(gz)
@@ -2756,11 +2746,11 @@ class DimensionAnchorWidget(types.GizmoGroup):
 
         for i in range(n):
             gz = self._handles[i]
-            world_co = obj.matrix_world @ spline.points[i].co.to_3d()
+            raw_co = spline.points[i].co
+            world_co = obj.matrix_world @ raw_co.to_3d()
             gz.matrix_basis = Matrix.Translation(world_co)
             gz.anchor_index = i
             if i == _active_anchor_idx and obj is _editing_annotation_obj:
-                print(f"[refresh] setting anchor[{i}] BLUE  (obj={obj.name}  editing={_editing_annotation_obj.name if _editing_annotation_obj else None})")
                 gz.color = (0.2, 0.7, 1.0)
                 gz.color_highlight = (0.4, 0.85, 1.0)
             elif anchors[i].get("guid"):
@@ -2777,7 +2767,6 @@ class DimensionAnchorWidget(types.GizmoGroup):
             self._handles[i].hide = True
 
     def draw_prepare(self, context: bpy.types.Context) -> None:
-        print(f"[draw_prepare] DimensionAnchorWidget  _active_anchor_idx={_active_anchor_idx}")
         self.refresh(context)
 
 

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

@@ -70,6 +70,84 @@ def _rebuild_dim_guid_index(file) -> None:
     _dim_index_dirty = False
 
 
+def regenerate_dims_for_layer(file, layer) -> None:
+    """Regenerate all parametric dimensions anchored to elements that use *layer*."""
+    global _dim_shape_cache, _dim_index_dirty, _dim_guid_index
+
+    if _dim_index_dirty:
+        _rebuild_dim_guid_index(file)
+
+    affected_guids: set = set()
+    for layer_set in file.get_inverse(layer):
+        if not layer_set.is_a("IfcMaterialLayerSet"):
+            continue
+        for inv in file.get_inverse(layer_set):
+            if inv.is_a("IfcRelAssociatesMaterial"):
+                rels = [inv]
+            elif inv.is_a("IfcMaterialLayerSetUsage"):
+                rels = [r for r in file.get_inverse(inv) if r.is_a("IfcRelAssociatesMaterial")]
+            else:
+                continue
+            for rel in rels:
+                for element in rel.RelatedObjects:
+                    if hasattr(element, "GlobalId"):
+                        affected_guids.add(element.GlobalId)
+                        _dim_shape_cache.pop(element.id(), None)
+
+    if not affected_guids:
+        return
+
+    annotation_ids: set = set()
+    for guid in affected_guids:
+        for ann_id in _dim_guid_index.get(guid, []):
+            annotation_ids.add(ann_id)
+
+    if not annotation_ids:
+        return
+
+    import ifcopenshell.util.element
+    import ifcopenshell.api.drawing as drawing_api
+    import ifcopenshell.geom
+    from bonsai.bim.module.drawing.operator import _update_blender_curve
+
+    geom_settings = ifcopenshell.geom.settings()
+    geom_settings.set("APPLY_DEFAULT_MATERIALS", False)
+
+    for ann_id in annotation_ids:
+        try:
+            annotation = file.by_id(ann_id)
+        except Exception:
+            continue
+        pset = ifcopenshell.util.element.get_pset(annotation, "BBIM_Dimension")
+        if not pset:
+            continue
+        placement_override: dict = {}
+        try:
+            anchors_raw = json.loads(pset.get("Anchors") or "[]")
+            for anchor in anchors_raw:
+                guid = anchor.get("guid")
+                if not guid:
+                    continue
+                try:
+                    elem = file.by_guid(guid)
+                    elem_obj = tool.Ifc.get_object(elem)
+                    if elem_obj:
+                        placement_override[elem.id()] = np.array(elem_obj.matrix_world)
+                except Exception:
+                    pass
+        except Exception:
+            pass
+        resolved_pts = drawing_api.regenerate_dimension(
+            file,
+            annotation,
+            settings=geom_settings,
+            shape_cache=_dim_shape_cache,
+            placement_override=placement_override,
+        )
+        if resolved_pts:
+            _update_blender_curve(annotation, resolved_pts)
+
+
 @persistent
 def load_post(*args):
     invalidate_dim_index()
@@ -140,10 +218,7 @@ def _sync_dimension_anchors_to_curve(file, annotation, obj) -> bool:
     n_pts = len(spline_world)
     n_anchors = len(anchors)
 
-    print(f"[sync_anchors] obj={obj.name}  spline_pts={n_pts}  anchors={n_anchors}")
-
     if n_pts == n_anchors:
-        print("[sync_anchors] counts match — no change needed")
         return False
 
     # Match each spline point to the nearest unused anchor by proximity.
@@ -177,7 +252,6 @@ def _sync_dimension_anchors_to_curve(file, annotation, obj) -> bool:
                 "pt": [pt.x, pt.y, pt.z],
             })
 
-    print(f"[sync_anchors] rebuilt {len(new_anchors)} anchors (was {n_anchors})")
 
     pset_entity = file.by_id(pset_data["id"])
     ifcopenshell.api.pset.edit_pset(file, pset=pset_entity, properties={"Anchors": json.dumps(new_anchors)})
@@ -197,10 +271,11 @@ def depsgraph_update_post_handler(scene, depsgraph):
     if not file:
         return
 
-    # Collect GUIDs of IFC objects whose transform or geometry changed.
-    # is_updated_geometry fires on Edit Mode exit after Bonsai has already
-    # serialised the new mesh back to IFC via update_representation, so the
-    # tessellation will reflect the edited shape.
+    if _dim_index_dirty:
+        _rebuild_dim_guid_index(file)
+
+    import ifcopenshell.util.element
+
     moved_guids: set = set()
     edited_annotation_ids: set = set()
 
@@ -214,26 +289,20 @@ def depsgraph_update_post_handler(scene, depsgraph):
         if element is None or not hasattr(element, "GlobalId"):
             continue
 
-        # If the dimension annotation curve itself was edited (vertex added/removed),
-        # sync the anchor list before regenerating.
+
         if update.is_updated_geometry and obj.type == "CURVE" and element.is_a("IfcAnnotation"):
             import ifcopenshell.util.element as _ue
             ptype = _ue.get_predefined_type(element)
-            print(f"[handler] dimension curve geometry updated: {obj.name}  ptype={ptype}  is_updated_geometry={update.is_updated_geometry}")
             if ptype in ("DIMENSION", "RADIUS", "DIAMETER", "ANGLE", "PLAN_LEVEL", "SECTION_LEVEL"):
-                _sync_dimension_anchors_to_curve(file, element, obj)
-                edited_annotation_ids.add(element.id())
+                changed = _sync_dimension_anchors_to_curve(file, element, obj)
+                if changed:
+                    edited_annotation_ids.add(element.id())
                 continue
 
         moved_guids.add(element.GlobalId)
-        # Geometry edits invalidate the cached tessellation for this element.
         if update.is_updated_geometry:
             _dim_shape_cache.pop(element.id(), None)
 
-    if _dim_index_dirty:
-        _rebuild_dim_guid_index(file)
-
-    print(f"[handler] edited_annotation_ids={edited_annotation_ids}  moved_guids={moved_guids}")
     annotation_ids: set = set(edited_annotation_ids)
     for guid in moved_guids:
         for ann_id in _dim_guid_index.get(guid, []):
@@ -244,7 +313,6 @@ def depsgraph_update_post_handler(scene, depsgraph):
 
     import ifcopenshell.api.drawing as drawing_api
     import ifcopenshell.geom
-    import ifcopenshell.util.element
     from bonsai.bim.module.drawing.operator import _update_blender_curve
 
     geom_settings = ifcopenshell.geom.settings()
@@ -282,7 +350,6 @@ def depsgraph_update_post_handler(scene, depsgraph):
             except Exception:
                 pass
 
-            print(f"[handler] regenerating ann_id={ann_id}  anchors_in_pset={len(json.loads(pset.get('Anchors') or '[]'))}")
             resolved_pts = drawing_api.regenerate_dimension(
                 file,
                 annotation,
@@ -290,13 +357,7 @@ def depsgraph_update_post_handler(scene, depsgraph):
                 shape_cache=_dim_shape_cache,
                 placement_override=placement_override,
             )
-            print(f"[handler] resolved_pts count={len(resolved_pts)}  pts={[(round(p[0],3),round(p[1],3),round(p[2],3)) for p in resolved_pts]}")
             if resolved_pts:
-                obj = tool.Ifc.get_object(annotation)
-                if obj:
-                    print(f"[handler] curve spline pts before update={len(obj.data.splines[0].points) if obj.data.splines else 0}")
                 _update_blender_curve(annotation, resolved_pts)
-                if obj:
-                    print(f"[handler] curve spline pts after update={len(obj.data.splines[0].points) if obj.data.splines else 0}")
     finally:
         _dim_handler_running = False

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

@@ -5701,19 +5701,42 @@ class DrawParametricDimension(bpy.types.Operator, PolylineOperator, tool.Ifc.Ope
     def _update_perp_constraint(self) -> None:
         """Extract the face normal from anchor[0] and store it as the constraint axis."""
         import math
+        from mathutils import Vector
         a = self._anchors[0] if self._anchors else None
         if not a or a.get("type") != "FACE":
+            print(f"[perp] _update_perp_constraint: anchor type={a.get('type') if a else None} — need FACE, skipping")
             return
-        fp = (a.get("addr") or {}).get("fingerprint") or {}
-        n = fp.get("normal")   # world-space at build time
+        addr = a.get("addr") or {}
+        normal_local = addr.get("normal_local")
         pt = a.get("pt")
-        if not n or not pt:
+        if not normal_local or not pt:
+            print(f"[perp] _update_perp_constraint: missing normal_local={normal_local} or pt={pt}")
             return
+
+        # Rotate element-local normal to world space via the Blender object's matrix.
+        n = normal_local
+        guid = a.get("guid")
+        if guid:
+            try:
+                file = tool.Ifc.get()
+                element = file.by_guid(guid)
+                obj = tool.Ifc.get_object(element)
+                if obj:
+                    nw = obj.matrix_world.to_3x3() @ Vector(normal_local)
+                    nw.normalize()
+                    n = (nw.x, nw.y, nw.z)
+                else:
+                    print(f"[perp] _update_perp_constraint: no Blender obj for guid={guid}, using normal_local as-is")
+            except Exception as exc:
+                print(f"[perp] _update_perp_constraint: exception rotating normal: {exc}")
+
         mag = math.sqrt(n[0] ** 2 + n[1] ** 2 + n[2] ** 2)
         if mag < 1e-12:
+            print(f"[perp] _update_perp_constraint: zero-length normal after rotation")
             return
         self._anchor0_normal = (n[0] / mag, n[1] / mag, n[2] / mag)
         self._anchor0_pt = tuple(pt)
+        print(f"[perp] _update_perp_constraint: OK  normal={[round(v,3) for v in self._anchor0_normal]}  pt={[round(v,3) for v in self._anchor0_pt]}")
 
     def _apply_perp_constraint(self) -> None:
         """Project the current snap point onto the constraint line when active."""
@@ -5730,7 +5753,9 @@ class DrawParametricDimension(bpy.types.Operator, PolylineOperator, tool.Ifc.Ope
         base = self._anchor0_pt
         n = self._anchor0_normal
         t = (p.x - base[0]) * n[0] + (p.y - base[1]) * n[1] + (p.z - base[2]) * n[2]
-        snap["point"] = Vector((base[0] + t * n[0], base[1] + t * n[1], base[2] + t * n[2]))
+        constrained = Vector((base[0] + t * n[0], base[1] + t * n[1], base[2] + t * n[2]))
+        print(f"[perp] _apply_perp_constraint: raw=({p.x:.3f},{p.y:.3f},{p.z:.3f})  t={t:.4f}  constrained=({constrained.x:.3f},{constrained.y:.3f},{constrained.z:.3f})")
+        snap["point"] = constrained
 
     # ------------------------------------------------------------------
     # Finalize: create IfcAnnotation + BBIM_Dimension pset
@@ -5917,7 +5942,85 @@ def _prefer_perp_face_index(
     return best_idx
 
 
-class SetDimensionAnchor(bpy.types.Operator):
+# Module-level draw data so the GPU callback never touches the operator RNA struct.
+_snap_draw_data: dict = {}
+
+
+
+def _draw_snap_indicator_global():
+    """GPU draw callback (POST_VIEW) — draws face outline, edge, or vertex dot."""
+    data = _snap_draw_data
+    if not data or not data.get("type"):
+        return
+    import gpu
+    from gpu_extras.batch import batch_for_shader
+    try:
+        shader = gpu.shader.from_builtin("UNIFORM_COLOR")
+        gpu.state.blend_set("ALPHA")
+        gpu.state.depth_test_set("ALWAYS")
+        snap_type = data["type"]
+
+        if snap_type == "FACE":
+            verts = data.get("face_verts", [])
+            if len(verts) >= 3:
+                lines = []
+                for i in range(len(verts)):
+                    lines.append(verts[i])
+                    lines.append(verts[(i + 1) % len(verts)])
+                shader.bind()
+                shader.uniform_float("color", (0.2, 0.55, 1.0, 0.9))
+                gpu.state.line_width_set(4.0)
+                batch_for_shader(shader, "LINES", {"pos": lines}).draw(shader)
+
+        elif snap_type == "EDGE":
+            v0, v1 = data.get("v0"), data.get("v1")
+            if v0 and v1:
+                shader.bind()
+                shader.uniform_float("color", (1.0, 0.65, 0.0, 1.0))
+                gpu.state.line_width_set(6.0)
+                batch_for_shader(shader, "LINES", {"pos": [v0, v1]}).draw(shader)
+                gpu.state.point_size_set(12.0)
+                batch_for_shader(shader, "POINTS", {"pos": [v0, v1]}).draw(shader)
+
+        elif snap_type == "VERTEX":
+            pt = data.get("snap_world")
+            if pt:
+                shader.bind()
+                shader.uniform_float("color", (1.0, 0.2, 0.4, 1.0))
+                gpu.state.point_size_set(20.0)
+                batch_for_shader(shader, "POINTS", {"pos": [pt]}).draw(shader)
+
+        elif snap_type == "LAYER":
+            corners = data.get("seam_corners", [])
+            pt = data.get("snap_world")
+            shader.bind()
+            shader.uniform_float("color", (0.2, 0.9, 0.5, 1.0))
+            n = len(corners)
+            if n >= 2:
+                lines = []
+                for i in range(n):
+                    lines.append(corners[i])
+                    lines.append(corners[(i + 1) % n])
+                gpu.state.line_width_set(5.0)
+                batch_for_shader(shader, "LINES", {"pos": lines}).draw(shader)
+                gpu.state.point_size_set(10.0)
+                batch_for_shader(shader, "POINTS", {"pos": corners}).draw(shader)
+            if pt:
+                gpu.state.point_size_set(20.0)
+                batch_for_shader(shader, "POINTS", {"pos": [pt]}).draw(shader)
+
+    except Exception:
+        pass
+    finally:
+        try:
+            gpu.state.depth_test_set("LESS_EQUAL")
+            gpu.state.blend_set("NONE")
+            gpu.state.line_width_set(1.0)
+        except Exception:
+            pass
+
+
+class SetDimensionAnchor(bpy.types.Operator, tool.Ifc.Operator):
     """Interactively anchor dimension vertices to IFC element faces.
 
     Two-phase modal workflow (all in Object Mode):
@@ -5950,12 +6053,17 @@ class SetDimensionAnchor(bpy.types.Operator):
 
     # Hover-cycle state (active during PICK_FACE phase)
     _hover_candidates: list   # [(ifc_obj, hit_mesh, hit_mesh_mx, location, normal, face_index), ...]
-    _hover_index: int         # which candidate is currently highlighted
+    _hover_index: int         # which element candidate is currently highlighted
     _hover_last_px: tuple     # last cursor pixel position where candidates were computed
     _hover_highlighted_obj: Optional[bpy.types.Object]  # object currently selected for highlight
 
-    _VERTEX_PICK_RADIUS_PX = 20   # pixels — how close the click must be to a vertex
-    _HOVER_THROTTLE_PX_SQ = 25    # only recompute candidates if cursor moves >5px
+    # Snap-mode cycle state (FACE → EDGE → VERTEX, TAB)
+    _snap_mode: str           # "FACE" | "EDGE" | "VERTEX"
+    _draw_handler: object     # SpaceView3D draw handler handle
+
+    _VERTEX_PICK_RADIUS_PX = 20
+    _HOVER_THROTTLE_PX_SQ = 25
+    _SNAP_MODES = ("FACE", "LAYER", "EDGE", "VERTEX")
 
     @classmethod
     def poll(cls, context):
@@ -5980,6 +6088,12 @@ class SetDimensionAnchor(bpy.types.Operator):
         return True
 
     def invoke(self, context, event):
+        return IfcStore.execute_ifc_operator(self, context, event, method="INVOKE")
+
+    def modal(self, context, event):
+        return IfcStore.execute_ifc_operator(self, context, event, method="MODAL")
+
+    def _invoke(self, context, event):
         obj = context.active_object
         self._annotation = tool.Ifc.get_entity(obj)
         self._annotation_obj = obj
@@ -5996,6 +6110,11 @@ class SetDimensionAnchor(bpy.types.Operator):
         self._hover_index = 0
         self._hover_last_px = (-9999, -9999)
         self._hover_highlighted_obj = None
+        self._snap_mode = "FACE"
+        _snap_draw_data.clear()
+        self._draw_handler = bpy.types.SpaceView3D.draw_handler_add(
+            _draw_snap_indicator_global, (), "WINDOW", "POST_VIEW"
+        )
 
         # When invoked from a panel, context.region_data is None.
         # Walk the screen areas to find the actual 3D viewport region.
@@ -6014,13 +6133,28 @@ class SetDimensionAnchor(bpy.types.Operator):
         context.window_manager.modal_handler_add(self)
         return {"RUNNING_MODAL"}
 
-    def modal(self, context, event):
+    def _modal(self, context, event):
+        # Undo while the modal is running can free the annotation object.
+        try:
+            _ = self._annotation_obj.name
+        except ReferenceError:
+            self._cleanup(context)
+            return {"FINISHED"}
+
         if event.type == "ESC" or (event.type == "RIGHTMOUSE" and event.value == "PRESS"):
             self._clear_hover_highlight(context)
             context.workspace.status_text_set(None)
+            _snap_draw_data.clear()
+            if self._draw_handler:
+                bpy.types.SpaceView3D.draw_handler_remove(self._draw_handler, "WINDOW")
+                self._draw_handler = None
             from bonsai.bim.module.drawing.gizmos import set_active_anchor
             set_active_anchor(-1)
-            return {"FINISHED"}  # keep any anchors already written
+            obj = context.active_object
+            if obj:
+                obj.select_set(False)
+                context.view_layer.objects.active = None
+            return {"FINISHED"}
 
         # Hover — recompute candidates as cursor moves (PICK_FACE phase only)
         if event.type == "MOUSEMOVE" and self._phase == "PICK_FACE":
@@ -6036,12 +6170,32 @@ class SetDimensionAnchor(bpy.types.Operator):
             if self._phase == "PICK_VERTEX":
                 self._handle_vertex_pick(context, event)
             else:
-                self._handle_face_pick(context, event)
+                wrote = self._handle_face_pick(context, event)
+                if wrote:
+                    # Finish here so this anchor write is its own undo step.
+                    # The dimension stays selected so the user can click
+                    # another dot immediately.
+                    self._cleanup(context)
+                    return {"FINISHED"}
             self._set_status(context)
             return {"RUNNING_MODAL"}
 
         return {"PASS_THROUGH"}
 
+    def _cleanup(self, context):
+        self._clear_hover_highlight(context)
+        context.workspace.status_text_set(None)
+        _snap_draw_data.clear()
+        if self._draw_handler:
+            bpy.types.SpaceView3D.draw_handler_remove(self._draw_handler, "WINDOW")
+            self._draw_handler = None
+        from bonsai.bim.module.drawing.gizmos import set_active_anchor
+        set_active_anchor(-1)
+        for area in context.screen.areas:
+            if area.type == "VIEW_3D":
+                area.tag_redraw()
+                break
+
     # ------------------------------------------------------------------
     # Status bar
 
@@ -6136,12 +6290,9 @@ class SetDimensionAnchor(bpy.types.Operator):
             pt_m = list(alt_loc) if alt_loc else list(origin + direction * 5.0)
             import ifcopenshell.api.drawing as drawing_api
             anchor = drawing_api.make_world_anchor(pt_m)
-            self._write_anchor(anchor, self._active_vertex_idx)
+            _do_write_anchor(self._annotation, self._annotation_obj, anchor, self._active_vertex_idx, self._shape_cache)
             self.report({"INFO"}, f"Vertex {self._active_vertex_idx} → free world point")
-            self._phase = "PICK_VERTEX"
-            from bonsai.bim.module.drawing.gizmos import set_active_anchor
-            set_active_anchor(-1)
-            return
+            return True
 
         # Normal click — use whichever candidate is currently highlighted.
         self._clear_hover_highlight(context)
@@ -6166,33 +6317,47 @@ class SetDimensionAnchor(bpy.types.Operator):
             return
 
         file = tool.Ifc.get()
-        hit_m = (float(location.x), float(location.y), float(location.z))
-        normal_m = (float(normal.x), float(normal.y), float(normal.z))
         placement_override = {element.id(): np.array(hit_obj.matrix_world)}
 
+        # Recompute snap geometry at the exact click position for accuracy.
+        snap = self._compute_snap_geom(hit_obj, face_index, coord)
+        snap_type = snap.get("type", "FACE")
+
         import ifcopenshell.api.drawing as drawing_api
         try:
-            anchor = drawing_api.build_anchor_from_hit(
-                file, element, hit_m, normal_m,
-                shape_cache=self._shape_cache,
-                placement_override=placement_override,
-            )
+            if snap_type == "LAYER" and snap.get("method") == "LAYER_BOUNDARY":
+                anchor = drawing_api.build_anchor_from_layer_boundary(file, element, snap)
+            elif snap_type == "VERTEX" and snap.get("profile_x_m") is not None:
+                anchor = drawing_api.build_anchor_from_profile_vert(file, element, snap)
+            elif snap_type == "EDGE" and snap.get("profile_x_m") is not None:
+                anchor = drawing_api.build_anchor_from_profile_edge(file, element, snap)
+            elif snap_type in ("VERTEX", "EDGE") and snap.get("snap_world") is not None:
+                # Tessellation fallback — no IFC profile data available.
+                # Use the snap position as a static WORLD anchor rather than a
+                # FACE fingerprint, so the endpoint stays at the correct vertex/
+                # edge position instead of drifting to the face centre.
+                sw = snap["snap_world"]
+                anchor = drawing_api.make_world_anchor([float(sw[0]), float(sw[1]), float(sw[2])])
+            else:
+                hit_m = (float(location.x), float(location.y), float(location.z))
+                normal_m = (float(normal.x), float(normal.y), float(normal.z))
+                anchor = drawing_api.build_anchor_from_hit(
+                    file, element, hit_m, normal_m,
+                    shape_cache=self._shape_cache,
+                    placement_override=placement_override,
+                )
         except Exception as exc:
             import traceback
             traceback.print_exc()
-            self.report({"ERROR"}, f"build_anchor_from_hit failed: {exc}")
+            self.report({"ERROR"}, f"build_anchor failed: {exc}")
             return
 
-        self._write_anchor(anchor, self._active_vertex_idx)
+        _do_write_anchor(self._annotation, self._annotation_obj, anchor, self._active_vertex_idx, self._shape_cache)
         self.report(
             {"INFO"},
-            f"Vertex {self._active_vertex_idx} → {element.is_a()}/{element.Name or element.GlobalId}",
+            f"Vertex {self._active_vertex_idx} → {element.is_a()}/{element.Name or element.GlobalId} [{anchor.get('type')}]",
         )
-        self._phase = "PICK_VERTEX"
-        self._hover_candidates = []
-        self._hover_index = 0
-        from bonsai.bim.module.drawing.gizmos import set_active_anchor
-        set_active_anchor(-1)
+        return True
 
     # ------------------------------------------------------------------
     # Hover / cycle helpers
@@ -6285,7 +6450,10 @@ class SetDimensionAnchor(bpy.types.Operator):
             bb_ctr = sum((v for v in bb_world), Vector()) / 8
             t = (bb_ctr - origin).dot(direction)
             query_w = origin + t * direction
-            found, loc_l, nrm_l, fi = ifc_obj.closest_point_on_mesh(mx_inv @ query_w, distance=100.0)
+            try:
+                found, loc_l, nrm_l, fi = ifc_obj.closest_point_on_mesh(mx_inv @ query_w, distance=100.0)
+            except RuntimeError:
+                continue
             if not found:
                 continue
             loc_w = mx @ loc_l
@@ -6311,19 +6479,25 @@ class SetDimensionAnchor(bpy.types.Operator):
         self._apply_hover_highlight(context)
 
     def _cycle_hover(self, context):
-        """Advance to the next candidate and update the highlight."""
+        """Cycle snap mode (FACE → EDGE → VERTEX); advance element on wrap-around."""
         if not self._hover_candidates:
             return
-        self._hover_index = (self._hover_index + 1) % len(self._hover_candidates)
+        modes = self._SNAP_MODES
+        cur = modes.index(self._snap_mode)
+        nxt = (cur + 1) % len(modes)
+        self._snap_mode = modes[nxt]
+        if nxt == 0 and len(self._hover_candidates) > 1:
+            self._hover_index = (self._hover_index + 1) % len(self._hover_candidates)
         self._apply_hover_highlight(context)
 
     def _apply_hover_highlight(self, context):
-        """Select the current candidate object for visual feedback."""
+        """Select the current candidate object; compute snap geometry; update status."""
         if not self._hover_candidates:
             self._clear_hover_highlight(context)
+            _snap_draw_data.clear()
             return
 
-        ifc_obj = self._hover_candidates[self._hover_index][0]
+        ifc_obj, _, _, _, _, face_index = self._hover_candidates[self._hover_index]
 
         # Only update selection when the highlighted object changes.
         if ifc_obj != self._hover_highlighted_obj:
@@ -6339,14 +6513,22 @@ class SetDimensionAnchor(bpy.types.Operator):
             except Exception:
                 pass
 
+        _snap_draw_data.clear()
+        _snap_draw_data.update(self._compute_snap_geom(ifc_obj, face_index, self._hover_last_px))
+
         entity = tool.Ifc.get_entity(ifc_obj)
         label = (entity.Name or entity.GlobalId) if entity else ifc_obj.name
         n = len(self._hover_candidates)
-        cycle_hint = f"  |  TAB: cycle ({self._hover_index + 1}/{n})" if n > 1 else ""
+        mode_label = self._snap_mode.capitalize()
+        elem_hint = f" ({self._hover_index + 1}/{n})" if n > 1 else ""
         context.workspace.status_text_set(
-            f"Vertex {self._active_vertex_idx} — {ifc_obj.name}{cycle_hint}"
-            "  |  Click: anchor  |  ALT+Click: free point  |  RMB/ESC: Finish"
+            f"Dim vertex {self._active_vertex_idx} — {label}  [{mode_label}{elem_hint}]"
+            "  |  TAB: cycle snap  |  Click: anchor  |  ALT+Click: free  |  RMB/ESC: Finish"
         )
+        for area in context.screen.areas:
+            if area.type == "VIEW_3D":
+                area.tag_redraw()
+                break
 
     def _clear_hover_highlight(self, context):
         """Deselect the highlighted object and restore the annotation as active."""
@@ -6362,77 +6544,199 @@ class SetDimensionAnchor(bpy.types.Operator):
         except Exception:
             pass
 
+    def cancel(self, context):
+        """Called when the operator is cancelled externally — clean up GPU handler."""
+        _snap_draw_data.clear()
+        if self._draw_handler:
+            bpy.types.SpaceView3D.draw_handler_remove(self._draw_handler, "WINDOW")
+            self._draw_handler = None
+        from bonsai.bim.module.drawing.gizmos import set_active_anchor
+        set_active_anchor(-1)
+        obj = context.active_object
+        if obj:
+            obj.select_set(False)
+            context.view_layer.objects.active = None
+
     # ------------------------------------------------------------------
-    # Pset write (shared by both face and free-point paths)
+    # Snap geometry helpers
 
-    def _write_anchor(self, new_anchor: dict, vertex_index: int) -> None:
-        file = tool.Ifc.get()
-        annotation = self._annotation
+    def _compute_snap_geom(self, hit_obj, face_index, coord) -> dict:
+        """Return snap draw-data dict for the current snap mode and hit face.
 
-        pset_data = ifcopenshell.util.element.get_pset(annotation, "BBIM_Dimension")
+        When the hit element has an IfcExtrudedAreaSolid, VERTEX and EDGE snaps
+        are resolved from the IFC profile geometry (stable across mesh reloads)
+        rather than from Blender tessellation vertex indices.
 
-        if pset_data and pset_data.get("Anchors"):
-            try:
-                anchors: list = json.loads(pset_data["Anchors"])
-            except Exception:
-                anchors = []
-        else:
-            anchors = _anchors_from_spline(self._annotation_obj, file)
+        ``coord`` is a (x, y) tuple in region-local pixels.  Returns an empty
+        dict when the face index is invalid or the region is unavailable.
+        """
+        from bpy_extras.view3d_utils import location_3d_to_region_2d
 
-        while len(anchors) <= vertex_index:
-            obj = self._annotation_obj
-            idx = len(anchors)
-            if obj and obj.data and hasattr(obj.data, "splines") and obj.data.splines:
-                pts = obj.data.splines[0].points
-                if idx < len(pts):
-                    co = obj.matrix_world @ pts[idx].co.xyz
-                    import ifcopenshell.api.drawing as drawing_api
-                    anchors.append(drawing_api.make_world_anchor([float(co.x), float(co.y), float(co.z)]))
-                    continue
-            import ifcopenshell.api.drawing as drawing_api
-            anchors.append(drawing_api.make_world_anchor([0.0, 0.0, 0.0]))
+        region = self._region
+        rv3d = self._rv3d
+        if not region or not rv3d or face_index is None:
+            return {}
+        try:
+            face = hit_obj.data.polygons[face_index]
+        except (IndexError, AttributeError):
+            return {}
 
-        anchors[vertex_index] = new_anchor
-        anchors_json = json.dumps(anchors)
+        mx = hit_obj.matrix_world
+        face_verts_world = [tuple(mx @ hit_obj.data.vertices[vi].co) for vi in face.vertices]
 
-        if pset_data:
-            pset_entity = file.by_id(pset_data["id"])
-            ifcopenshell.api.run("pset.edit_pset", file, pset=pset_entity, properties={"Anchors": anchors_json})
-        else:
-            ifcopenshell.api.run("pset.add_pset", file, product=annotation, name="BBIM_Dimension")
-            pset_data = ifcopenshell.util.element.get_pset(annotation, "BBIM_Dimension")
-            pset_entity = file.by_id(pset_data["id"])
-            ifcopenshell.api.run("pset.edit_pset", file, pset=pset_entity, properties={"Anchors": anchors_json})
+        if self._snap_mode == "FACE":
+            return {"type": "FACE", "face_verts": face_verts_world}
 
-        from bonsai.bim.module.drawing import handler as _drawing_handler
-        _drawing_handler.invalidate_dim_index()
+        # Try profile-based snap candidates first (IFC-native, index-stable).
+        if self._snap_mode in ("VERTEX", "EDGE"):
+            element = tool.Ifc.get_entity(hit_obj)
+            if element:
+                import ifcopenshell.api.drawing as drawing_api
+                placement_override = {element.id(): np.array(mx)}
+                candidates = drawing_api.get_profile_snap_candidates(
+                    tool.Ifc.get(), element, placement_override=placement_override
+                )
+                want_type = self._snap_mode
+                best_cand = None
+                best_d2 = float("inf")
+                for cand in candidates:
+                    if cand["type"] != want_type:
+                        continue
+                    sp = location_3d_to_region_2d(region, rv3d, cand["snap_world"])
+                    if sp is None:
+                        continue
+                    dx, dy = sp.x - coord[0], sp.y - coord[1]
+                    d2 = dx * dx + dy * dy
+                    if d2 < best_d2:
+                        best_d2, best_cand = d2, cand
+                if best_cand is not None:
+                    return best_cand
 
-        # Move the Blender curve vertex to the newly resolved anchor position.
-        # Build placement_override from current Blender matrix_world so that
-        # elements whose IFC ObjectPlacement hasn't been synced yet resolve correctly.
-        placement_override: dict = {}
-        for a in anchors:
-            guid = a.get("guid")
-            if not guid:
+            # Fallback: Blender tessellation snap for elements without an
+            # IfcExtrudedAreaSolid profile.  Returns snap_world for the visual
+            # indicator; no pt_idx so the click handler creates a face anchor.
+            screen_pts = [location_3d_to_region_2d(region, rv3d, wv) for wv in face_verts_world]
+            n = len(face_verts_world)
+
+            if self._snap_mode == "VERTEX":
+                best_i, best_d2 = 0, float("inf")
+                for i, sp in enumerate(screen_pts):
+                    if sp is not None:
+                        dx, dy = sp.x - coord[0], sp.y - coord[1]
+                        d2 = dx * dx + dy * dy
+                        if d2 < best_d2:
+                            best_d2, best_i = d2, i
+                return {"type": "VERTEX", "snap_world": face_verts_world[best_i]}
+
+            if self._snap_mode == "EDGE":
+                best_e, best_d2 = 0, float("inf")
+                for i in range(n):
+                    j = (i + 1) % n
+                    sp0, sp1 = screen_pts[i], screen_pts[j]
+                    if sp0 is not None and sp1 is not None:
+                        mid_x = (sp0.x + sp1.x) * 0.5
+                        mid_y = (sp0.y + sp1.y) * 0.5
+                        dx, dy = mid_x - coord[0], mid_y - coord[1]
+                        d2 = dx * dx + dy * dy
+                        if d2 < best_d2:
+                            best_d2, best_e = d2, i
+                i0, i1 = best_e, (best_e + 1) % n
+                v0_w, v1_w = face_verts_world[i0], face_verts_world[i1]
+                mid_w = ((v0_w[0] + v1_w[0]) * 0.5, (v0_w[1] + v1_w[1]) * 0.5, (v0_w[2] + v1_w[2]) * 0.5)
+                return {"type": "EDGE", "v0": v0_w, "v1": v1_w, "snap_world": mid_w}
+
+        if self._snap_mode == "LAYER":
+            element = tool.Ifc.get_entity(hit_obj)
+            if element:
+                import ifcopenshell.api.drawing as drawing_api
+                placement_override = {element.id(): np.array(mx)}
+                candidates = drawing_api.get_layer_snap_candidates(
+                    tool.Ifc.get(), element, placement_override=placement_override
+                )
+                best_cand = None
+                best_d2 = float("inf")
+                for cand in candidates:
+                    sp = location_3d_to_region_2d(region, rv3d, cand["snap_world"])
+                    if sp is None:
+                        continue
+                    dx, dy = sp.x - coord[0], sp.y - coord[1]
+                    d2 = dx * dx + dy * dy
+                    if d2 < best_d2:
+                        best_d2, best_cand = d2, cand
+                if best_cand is not None:
+                    result = dict(best_cand)
+                    result["type"] = "LAYER"
+                    result["method"] = "LAYER_BOUNDARY"
+                    return result
+            return {"type": "FACE", "face_verts": face_verts_world}
+
+        return {}
+
+
+def _do_write_anchor(annotation, annotation_obj, new_anchor: dict, vertex_index: int, shape_cache=None) -> None:
+    """Write one anchor into the BBIM_Dimension pset and regenerate the curve."""
+    file = tool.Ifc.get()
+
+    pset_data = ifcopenshell.util.element.get_pset(annotation, "BBIM_Dimension")
+
+    if pset_data and pset_data.get("Anchors"):
+        try:
+            anchors: list = json.loads(pset_data["Anchors"])
+        except Exception:
+            anchors = []
+    else:
+        anchors = _anchors_from_spline(annotation_obj, file)
+
+    while len(anchors) <= vertex_index:
+        idx = len(anchors)
+        if annotation_obj and annotation_obj.data and hasattr(annotation_obj.data, "splines") and annotation_obj.data.splines:
+            pts = annotation_obj.data.splines[0].points
+            if idx < len(pts):
+                co = annotation_obj.matrix_world @ pts[idx].co.xyz
+                import ifcopenshell.api.drawing as drawing_api
+                anchors.append(drawing_api.make_world_anchor([float(co.x), float(co.y), float(co.z)]))
                 continue
-            try:
-                elem = file.by_guid(guid)
-                elem_obj = tool.Ifc.get_object(elem)
-                if elem_obj:
-                    placement_override[elem.id()] = np.array(elem_obj.matrix_world)
-            except Exception:
-                pass
-
         import ifcopenshell.api.drawing as drawing_api
-        resolved_pts = drawing_api.regenerate_dimension(
-            file,
-            annotation,
-            shape_cache=getattr(self, "_shape_cache", None),
-            placement_override=placement_override,
-        )
-        if resolved_pts:
-            _update_blender_curve(annotation, resolved_pts)
-        print(f"[write_anchor] resolved_pts={[(round(p[0],4),round(p[1],4),round(p[2],4)) for p in resolved_pts]}")
+        anchors.append(drawing_api.make_world_anchor([0.0, 0.0, 0.0]))
+
+    anchors[vertex_index] = new_anchor
+    anchors_json = json.dumps(anchors)
+
+    if pset_data:
+        pset_entity = file.by_id(pset_data["id"])
+        ifcopenshell.api.run("pset.edit_pset", file, pset=pset_entity, properties={"Anchors": anchors_json})
+    else:
+        ifcopenshell.api.run("pset.add_pset", file, product=annotation, name="BBIM_Dimension")
+        pset_data = ifcopenshell.util.element.get_pset(annotation, "BBIM_Dimension")
+        pset_entity = file.by_id(pset_data["id"])
+        ifcopenshell.api.run("pset.edit_pset", file, pset=pset_entity, properties={"Anchors": anchors_json})
+
+    from bonsai.bim.module.drawing import handler as _drawing_handler
+    _drawing_handler.invalidate_dim_index()
+
+    placement_override: dict = {}
+    for a in anchors:
+        guid = a.get("guid")
+        if not guid:
+            continue
+        try:
+            elem = file.by_guid(guid)
+            elem_obj = tool.Ifc.get_object(elem)
+            if elem_obj:
+                placement_override[elem.id()] = np.array(elem_obj.matrix_world)
+        except Exception:
+            pass
+
+    import ifcopenshell.api.drawing as drawing_api
+    resolved_pts = drawing_api.regenerate_dimension(
+        file,
+        annotation,
+        shape_cache=shape_cache,
+        placement_override=placement_override,
+    )
+    if resolved_pts:
+        _update_blender_curve(annotation, resolved_pts)
+
 
 
 class RegenerateDimensions(bpy.types.Operator, tool.Ifc.Operator):
@@ -6601,7 +6905,6 @@ def _update_blender_curve(
             spline.points.add(n - 1)
 
     is_2d = _annotation_is_2d(annotation)
-
     for i, pt_m in enumerate(resolved_pts_m):
         blender_world = Vector((float(pt_m[0]), float(pt_m[1]), float(pt_m[2])))
         local_pt = inv_world @ blender_world
@@ -6613,7 +6916,10 @@ def _update_blender_curve(
             spline.points[i].co = (*local_pt, 1.0)
 
     # Also update the IFC IfcPolyline so Edit Mode reloads reflect the new positions.
-    _update_ifc_polyline(tool.Ifc.get(), annotation, obj, resolved_pts_m)
+    try:
+        _update_ifc_polyline(tool.Ifc.get(), annotation, obj, resolved_pts_m)
+    except Exception as e:
+        pass
 
 
 def _annotation_is_2d(annotation: ifcopenshell.entity_instance) -> bool:
@@ -6716,46 +7022,24 @@ def _find_curve_in_item(item: ifcopenshell.entity_instance) -> Optional[ifcopens
     return None
 
 
-class ClickNearestDimensionAnchor(bpy.types.Operator):
-    """LMB handler: fire SetDimensionAnchor when cursor is within RADIUS pixels of an anchor dot.
 
-    Registered as a keymap item so it runs before Blender's object-selection handler.
-    Returns PASS_THROUGH when the cursor is not near any anchor, so normal viewport
-    clicks are unaffected.
+
+class ClickNearestDimensionAnchor(bpy.types.Operator):
+    """LMB fallback: fire SetDimensionAnchor when cursor is within RADIUS pixels of an anchor dot.
+
+    The gizmo handles exact hits; this catches near-misses where the cursor
+    is close to a dot but didn't land inside the gizmo hit shape.
     """
 
     bl_idname = "bim.click_nearest_dimension_anchor"
     bl_label = "Click Nearest Dimension Anchor"
 
-    RADIUS_PX = 120
+    RADIUS_PX = 60
 
     def invoke(self, context, event):
         from bpy_extras.view3d_utils import location_3d_to_region_2d
 
-        print(f"[AnchorClick] invoke called")
-
         if not tool.Ifc.get():
-            print(f"[AnchorClick] PASS_THROUGH — no IFC file")
-            return {"PASS_THROUGH"}
-
-        obj = context.active_object
-        if not obj or obj.type != "CURVE":
-            print(f"[AnchorClick] PASS_THROUGH — active obj is {obj} type={getattr(obj,'type',None)}")
-            return {"PASS_THROUGH"}
-
-        element = tool.Ifc.get_entity(obj)
-        if not element or not element.is_a("IfcAnnotation"):
-            print(f"[AnchorClick] PASS_THROUGH — not an IfcAnnotation: {element}")
-            return {"PASS_THROUGH"}
-
-        import ifcopenshell.util.element as _ue
-        pset = _ue.get_pset(element, "BBIM_Dimension")
-        if not pset or not pset.get("Anchors"):
-            print(f"[AnchorClick] PASS_THROUGH — no BBIM_Dimension pset or Anchors")
-            return {"PASS_THROUGH"}
-
-        if not obj.data.splines:
-            print(f"[AnchorClick] PASS_THROUGH — no splines")
             return {"PASS_THROUGH"}
 
         # Always use the 3D viewport WINDOW region — context.region may be a header,
@@ -6777,35 +7061,54 @@ class ClickNearestDimensionAnchor(bpy.types.Operator):
                 break
 
         if not region or not rv3d:
-            print(f"[AnchorClick] PASS_THROUGH — no 3D region")
             return {"PASS_THROUGH"}
 
         # Convert absolute mouse position to WINDOW region-local coordinates.
         cx = event.mouse_x - region.x
         cy = event.mouse_y - region.y
 
+        import ifcopenshell.util.element as _ue
+
         r2 = self.RADIUS_PX ** 2
+        best_obj = None
         best_idx = -1
         best_dist_sq = float("inf")
-        for i, pt in enumerate(obj.data.splines[0].points):
-            world_pos = obj.matrix_world @ pt.co.to_3d()
-            sp = location_3d_to_region_2d(region, rv3d, world_pos)
-            if not sp:
-                continue
-            dx, dy = cx - sp.x, cy - sp.y
-            d2 = dx * dx + dy * dy
-            print(f"[AnchorClick] click=({cx},{cy})  anchor[{i}]=({sp.x:.0f},{sp.y:.0f})  dist={d2**0.5:.1f}px  radius={self.RADIUS_PX}px")
-            if d2 < r2 and d2 < best_dist_sq:
-                best_dist_sq = d2
-                best_idx = i
 
-        if best_idx < 0:
-            print(f"[AnchorClick] MISS — no anchor within {self.RADIUS_PX}px")
+        # Scan ALL selected objects — context.active_object may have changed to an
+        # underlying IFC element due to Blender's hover pre-selection, so we can't
+        # rely on it being the dimension we want to click.
+        for obj in context.scene.objects:
+            if not obj.select_get():
+                continue
+            if obj.type != "CURVE":
+                continue
+            element = tool.Ifc.get_entity(obj)
+            if not element or not element.is_a("IfcAnnotation"):
+                continue
+            pset = _ue.get_pset(element, "BBIM_Dimension")
+            if not pset or not pset.get("Anchors"):
+                continue
+            if not obj.data.splines:
+                continue
+
+            for i, pt in enumerate(obj.data.splines[0].points):
+                world_pos = obj.matrix_world @ pt.co.to_3d()
+                sp = location_3d_to_region_2d(region, rv3d, world_pos)
+                if not sp:
+                    continue
+                dx, dy = cx - sp.x, cy - sp.y
+                d2 = dx * dx + dy * dy
+                if d2 < r2 and d2 < best_dist_sq:
+                    best_dist_sq = d2
+                    best_idx = i
+                    best_obj = obj
+
+        if best_obj is None:
             return {"PASS_THROUGH"}
 
-        print(f"[AnchorClick] HIT anchor[{best_idx}]  dist={best_dist_sq**0.5:.1f}px")
+        context.view_layer.objects.active = best_obj
         from bonsai.bim.module.drawing.gizmos import set_active_anchor
-        set_active_anchor(best_idx, obj)
+        set_active_anchor(best_idx, best_obj)
         # Force viewport redraw so gizmo colors update before the modal starts.
         for area in context.screen.areas:
             if area.type == "VIEW_3D":

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

@@ -834,6 +834,8 @@ class EditMaterialSetItem(bpy.types.Operator, tool.Ifc.Operator):
             )
             slab.DumbSlabPlaner().regenerate_from_layer(layer)
             wall.DumbWallPlaner().regenerate_from_layer(layer)
+            from bonsai.bim.module.drawing.handler import regenerate_dims_for_layer
+            regenerate_dims_for_layer(self.file, layer)
         elif material.is_a("IfcMaterialProfileSet"):
             profile_def = None
             if mprops.profiles:

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

@@ -90,7 +90,6 @@ class DisablePsetEditing(bpy.types.Operator, tool.Ifc.Operator):
 
 def _regenerate_parametric_dimension(file, annotation):
     """Regenerate a single parametric dimension annotation after a pset edit."""
-    print(f"[regen_dim] called for annotation={annotation.id()} {annotation.is_a()}")
     try:
         import json
         import numpy as np
@@ -100,13 +99,10 @@ def _regenerate_parametric_dimension(file, annotation):
         from bonsai.bim.module.drawing.operator import _update_blender_curve
 
         pset_data = ifcopenshell.util.element.get_pset(annotation, "BBIM_Dimension")
-        print(f"[regen_dim] pset_data keys={list(pset_data.keys()) if pset_data else None}")
         if not pset_data or not pset_data.get("Anchors"):
-            print("[regen_dim] no Anchors — skipping")
             return
 
         anchors = json.loads(pset_data["Anchors"])
-        print(f"[regen_dim] {len(anchors)} anchors")
         placement_override = {}
         for a in anchors:
             guid = a.get("guid")
@@ -117,17 +113,14 @@ def _regenerate_parametric_dimension(file, annotation):
                 elem_obj = _tool.Ifc.get_object(elem)
                 if elem_obj:
                     placement_override[elem.id()] = np.array(elem_obj.matrix_world)
-                    print(f"[regen_dim]   placement_override added for {elem.is_a()} id={elem.id()}")
-            except Exception as e:
-                print(f"[regen_dim]   placement_override error: {e}")
+            except Exception:
+                pass
 
         resolved_pts = drawing_api.regenerate_dimension(
             file, annotation, placement_override=placement_override
         )
-        print(f"[regen_dim] resolved_pts={resolved_pts}")
         if resolved_pts:
             _update_blender_curve(annotation, resolved_pts)
-            print("[regen_dim] _update_blender_curve done")
     except Exception:
         import traceback
         traceback.print_exc()
@@ -197,12 +190,9 @@ class EditPset(bpy.types.Operator, tool.Ifc.Operator):
             )
             if tool.Cost.has_schedules():
                 tool.Cost.update_cost_items(pset=pset)
-        print(f"[edit_pset] pset_name='{props.active_pset_name}'  element={element.is_a()}  before disable_pset_editing")
         is_bbim_dimension = props.active_pset_name == "BBIM_Dimension" and element.is_a("IfcAnnotation")
 
         bpy.ops.bim.disable_pset_editing(obj=self.obj, obj_type=self.obj_type)
-
-        print(f"[edit_pset] pset_name after disable='{props.active_pset_name}'  is_bbim_dimension={is_bbim_dimension}")
         if is_bbim_dimension:
             _regenerate_parametric_dimension(self.file, element)
 

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

@@ -26,7 +26,7 @@ from .. import wrap_usecases
 from .assign_product import assign_product
 from .edit_text_literal import edit_text_literal
 from .regenerate_dimension import regenerate_dimension, get_dimension_segment_lengths
-from .resolve_anchor import build_anchor_from_hit, make_world_anchor, resolve_anchor
+from .resolve_anchor import build_anchor_from_hit, build_anchor_from_layer_boundary, build_anchor_from_profile_vert, build_anchor_from_profile_edge, get_layer_snap_candidates, get_profile_snap_candidates, make_world_anchor, resolve_anchor
 from .unassign_product import unassign_product
 
 wrap_usecases(__path__, __name__)
@@ -34,8 +34,13 @@ wrap_usecases(__path__, __name__)
 __all__ = [
     "assign_product",
     "build_anchor_from_hit",
+    "build_anchor_from_layer_boundary",
+    "build_anchor_from_profile_edge",
+    "build_anchor_from_profile_vert",
     "edit_text_literal",
     "get_dimension_segment_lengths",
+    "get_layer_snap_candidates",
+    "get_profile_snap_candidates",
     "make_world_anchor",
     "regenerate_dimension",
     "resolve_anchor",

src/ifcopenshell-python/ifcopenshell/api/drawing/regenerate_dimension.py

@@ -296,33 +296,44 @@ def _get_anchor_face_normal_world(
 ) -> Optional[tuple[float, float, float]]:
     """Return the world-space unit face normal stored in a FACE anchor, or None.
 
-    Prefers ``normal_local`` (element-local, rotation-invariant) transformed by
-    the current element placement.  Falls back to the stored world-space normal.
+    Reads ``normal_local`` (element-local, rotation-invariant) from the anchor
+    addr and rotates it to world space via the current element placement.
+    Also accepts the legacy ``addr.fingerprint.normal_local`` format.
     """
     if anchor.get("type") != "FACE":
         return None
     guid = anchor.get("guid")
     if not guid:
         return None
-    fp = (anchor.get("addr") or {}).get("fingerprint") or {}
+    try:
+        element = file.by_guid(guid)
+    except Exception:
+        return None
 
-    normal_local = fp.get("normal_local")
-    if normal_local:
-        try:
-            element = file.by_guid(guid)
-        except Exception:
+    addr = anchor.get("addr") or {}
+    from .resolve_anchor import _rotate_local_to_world
+
+    if addr.get("method") == "LAYER_BOUNDARY":
+        import ifcopenshell.util.element as _ifc_elem
+        usage = _ifc_elem.get_material(element, should_inherit=True)
+        if not usage or not usage.is_a("IfcMaterialLayerSetUsage"):
+            return None
+        axis = (getattr(usage, "LayerSetDirection", None) or "AXIS2")
+        if axis == "AXIS1":
+            normal_local: tuple = (1.0, 0.0, 0.0)
+        elif axis == "AXIS3":
+            normal_local = (0.0, 0.0, 1.0)
+        else:
+            normal_local = (0.0, 1.0, 0.0)
+    else:
+        # FACE_NORMAL: normal_local stored in addr (new) or addr.fingerprint (legacy).
+        normal_local = addr.get("normal_local") or (addr.get("fingerprint") or {}).get("normal_local")
+        if not normal_local:
             return None
-        from .resolve_anchor import _rotate_local_to_world
-        n = _rotate_local_to_world(element, normal_local, placement_override)
-        mag = math.sqrt(n[0] ** 2 + n[1] ** 2 + n[2] ** 2)
-        return (n[0] / mag, n[1] / mag, n[2] / mag) if mag > 1e-12 else None
 
-    normal_world = fp.get("normal")
-    if normal_world:
-        mag = math.sqrt(sum(x * x for x in normal_world))
-        return tuple(x / mag for x in normal_world) if mag > 1e-12 else None  # type: ignore[return-value]
-
-    return None
+    n = _rotate_local_to_world(element, normal_local, placement_override)
+    mag = math.sqrt(n[0] ** 2 + n[1] ** 2 + n[2] ** 2)
+    return (n[0] / mag, n[1] / mag, n[2] / mag) if mag > 1e-12 else None
 
 
 def _get_line_offset_direction(