From acd62c59d0b01f2fb28466e365689d3d3027f0bb Mon Sep 17 00:00:00 2001
From: Ryan Schultz <ryan@openingdesign.com>
Date: Fri, 17 Apr 2026 08:04:00 -0500
Subject: [PATCH] Regenerate connected walls when recalculating a slab

When Shift+G is pressed on a LAYER3 element, any LAYER2 walls
connected via IfcRelConnectsElements(TOP) are now re-clipped
to the slab's updated geometry after recalculate_slab runs.

Generated with the assistance of an AI coding tool.
---
 src/bonsai/bonsai/bim/module/model/workspace.py |  3 +++
 src/bonsai/bonsai/core/tool.py                  |  1 +
 src/bonsai/bonsai/tool/model.py                 | 11 +++++++++++
 3 files changed, 15 insertions(+)

diff --git a/src/bonsai/bonsai/bim/module/model/workspace.py b/src/bonsai/bonsai/bim/module/model/workspace.py
index a6e5794c11..5b08563dab 100644
--- a/src/bonsai/bonsai/bim/module/model/workspace.py
+++ b/src/bonsai/bonsai/bim/module/model/workspace.py
@@ -1303,6 +1303,9 @@ class Hotkey(bpy.types.Operator, tool.Ifc.Operator):
                 bpy.ops.bim.recalculate_wall()
         elif self.active_material_usage == "LAYER3":
             bpy.ops.bim.recalculate_slab()
+            wall_objs = tool.Model.get_connected_wall_objs(element)
+            if wall_objs:
+                core.regenerate_wall_to_underside(tool.Ifc, tool.Geometry, tool.Model, wall_objs)
         elif tool.System.get_ports(element):
             bpy.ops.bim.regenerate_distribution_element()
         elif self.active_material_usage == "PROFILE":
diff --git a/src/bonsai/bonsai/core/tool.py b/src/bonsai/bonsai/core/tool.py
index f1b1807bbd..8b94b5dc21 100644
--- a/src/bonsai/bonsai/core/tool.py
+++ b/src/bonsai/bonsai/core/tool.py
@@ -682,6 +682,7 @@ class Model:
     def generate_occurrence_name(cls, element_type, ifc_class): pass
     def get_extrusion(cls, representation): pass
     def get_connected_slab_objs(cls, wall): pass
+    def get_connected_wall_objs(cls, slab): pass
     def get_manual_booleans(cls, element): pass
     def get_material_layer_parameters(cls, element): pass
     def get_slab_clipping_bmesh(cls, obj): pass
diff --git a/src/bonsai/bonsai/tool/model.py b/src/bonsai/bonsai/tool/model.py
index 502b7fb01d..210ce740ef 100644
--- a/src/bonsai/bonsai/tool/model.py
+++ b/src/bonsai/bonsai/tool/model.py
@@ -854,6 +854,17 @@ class Model(bonsai.core.tool.Model):
                     result.append(slab_obj)
         return result
 
+    @classmethod
+    def get_connected_wall_objs(cls, slab: ifcopenshell.entity_instance) -> list[bpy.types.Object]:
+        """Return Blender objects for LAYER2 walls connected to slab via IfcRelConnectsElements(TOP)."""
+        result = []
+        for rel in slab.ConnectedTo:
+            if rel.is_a("IfcRelConnectsElements") and rel.Description == "TOP":
+                wall_obj = tool.Ifc.get_object(rel.RelatedElement)
+                if wall_obj:
+                    result.append(wall_obj)
+        return result
+
     @classmethod
     def remove_wall_to_underside_booleans(cls, wall: ifcopenshell.entity_instance) -> None:
         """Remove all IfcBooleanResult items previously added by extend_walls_to_underside."""