From 91d67e6371e6ac9fbd2e01b208102f49d635d940 Mon Sep 17 00:00:00 2001
From: sboddy <stephen.j.boddy@gmail.com>
Date: Tue, 11 Nov 2025 19:57:52 +0000
Subject: [PATCH] Improve Merge/Mirror error messages to reduce confusion.
 (#6911)

---
 src/bonsai/bonsai/bim/module/model/workspace.py | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/src/bonsai/bonsai/bim/module/model/workspace.py b/src/bonsai/bonsai/bim/module/model/workspace.py
index 0aa7f7113e..30acee46e3 100644
--- a/src/bonsai/bonsai/bim/module/model/workspace.py
+++ b/src/bonsai/bonsai/bim/module/model/workspace.py
@@ -1322,6 +1322,20 @@ class Hotkey(bpy.types.Operator, tool.Ifc.Operator):
         if not bpy.context.selected_objects:
             return
         if self.active_material_usage == "LAYER2":
+            if len(bpy.context.selected_objects) != 2:
+                self.report(
+                    {"ERROR"},
+                    "Exactly two LAYER2 items (walls, railings, etc) must be selected to perform a merge.",
+                )
+                return
+            for item in bpy.context.selected_objects:
+                element = tool.Ifc.get_entity(item)
+                if tool.Model.get_usage_type(element) != "LAYER2":
+                    self.report(
+                        {"ERROR"},
+                        "Both selected items must be LAYER2 (walls, railings, etc) to perform a merge.",
+                    )
+                    return
             bpy.ops.bim.merge_wall()
         else:
             if len(bpy.context.selected_objects) == 1: