From bc89ac167dd8ce29a5677de4abd01bc1f7d8f43d Mon Sep 17 00:00:00 2001
From: Whatstone <whatston3@gmail.com>
Date: Sat, 8 Feb 2025 21:22:43 -0500
Subject: [PATCH 1/2] BorgSystem: check droppable items for duped mods

---
 .../Silicons/Borgs/BorgSystem.Modules.cs      | 27 ++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/Content.Server/Silicons/Borgs/BorgSystem.Modules.cs b/Content.Server/Silicons/Borgs/BorgSystem.Modules.cs
index d955813ddfd..b8d6b4561e7 100644
--- a/Content.Server/Silicons/Borgs/BorgSystem.Modules.cs
+++ b/Content.Server/Silicons/Borgs/BorgSystem.Modules.cs
@@ -369,7 +369,9 @@ public bool CanInsertModule(EntityUid uid, EntityUid module, BorgChassisComponen
                     continue;
 
                 if (containedItemModuleComp.Items.Count == itemModuleComp.Items.Count &&
-                    containedItemModuleComp.Items.All(itemModuleComp.Items.Contains))
+                    containedItemModuleComp.DroppableItems.Count == itemModuleComp.DroppableItems.Count && // Frontier
+                    containedItemModuleComp.Items.All(itemModuleComp.Items.Contains) &&
+                    containedItemModuleComp.DroppableItems.All(x => itemModuleComp.DroppableItems.Contains(x, new DroppableBorgItemComparer()))) // Frontier
                 {
                     if (user != null)
                         Popup.PopupEntity(Loc.GetString("borg-module-duplicate"), uid, user.Value);
@@ -381,6 +383,29 @@ public bool CanInsertModule(EntityUid uid, EntityUid module, BorgChassisComponen
         return true;
     }
 
+    // Frontier: droppable borg item comparator
+    private sealed class DroppableBorgItemComparer : IEqualityComparer<DroppableBorgItem>
+    {
+        public bool Equals(DroppableBorgItem? x, DroppableBorgItem? y)
+        {
+            // Same object
+            if (ReferenceEquals(x, y))
+                return true;
+            // Comparisons vs. null
+            if (x is null || y is null)
+                return false;
+            // Otherwise, use EntProtoId of item to keep
+            return x.ID == y.ID;
+        }
+
+        public int GetHashCode(DroppableBorgItem obj)
+        {
+            if (obj is null) return 0;
+            return obj.ID.GetHashCode();
+        }
+    }
+    // End Frontier
+
     /// <summary>
     /// Check if a module can be removed from a borg.
     /// </summary>

From e4a1322c305d83dc1519d1f2a3c92e6952f8d4cf Mon Sep 17 00:00:00 2001
From: Whatstone <whatston3@gmail.com>
Date: Mon, 10 Feb 2025 17:54:17 -0500
Subject: [PATCH 2/2] Cache item comparer

---
 .../Silicons/Borgs/BorgSystem.Modules.cs           | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/Content.Server/Silicons/Borgs/BorgSystem.Modules.cs b/Content.Server/Silicons/Borgs/BorgSystem.Modules.cs
index b8d6b4561e7..5eafc0ce8d8 100644
--- a/Content.Server/Silicons/Borgs/BorgSystem.Modules.cs
+++ b/Content.Server/Silicons/Borgs/BorgSystem.Modules.cs
@@ -363,6 +363,7 @@ public bool CanInsertModule(EntityUid uid, EntityUid module, BorgChassisComponen
 
         if (TryComp<ItemBorgModuleComponent>(module, out var itemModuleComp))
         {
+            var droppableComparer = new DroppableBorgItemComparer(); // Frontier: cached comparer
             foreach (var containedModuleUid in component.ModuleContainer.ContainedEntities)
             {
                 if (!TryComp<ItemBorgModuleComponent>(containedModuleUid, out var containedItemModuleComp))
@@ -371,7 +372,7 @@ public bool CanInsertModule(EntityUid uid, EntityUid module, BorgChassisComponen
                 if (containedItemModuleComp.Items.Count == itemModuleComp.Items.Count &&
                     containedItemModuleComp.DroppableItems.Count == itemModuleComp.DroppableItems.Count && // Frontier
                     containedItemModuleComp.Items.All(itemModuleComp.Items.Contains) &&
-                    containedItemModuleComp.DroppableItems.All(x => itemModuleComp.DroppableItems.Contains(x, new DroppableBorgItemComparer()))) // Frontier
+                    containedItemModuleComp.DroppableItems.All(x => itemModuleComp.DroppableItems.Contains(x, droppableComparer))) // Frontier
                 {
                     if (user != null)
                         Popup.PopupEntity(Loc.GetString("borg-module-duplicate"), uid, user.Value);
@@ -388,19 +389,20 @@ private sealed class DroppableBorgItemComparer : IEqualityComparer<DroppableBorg
     {
         public bool Equals(DroppableBorgItem? x, DroppableBorgItem? y)
         {
-            // Same object
+            // Same object (or both null)
             if (ReferenceEquals(x, y))
                 return true;
-            // Comparisons vs. null
-            if (x is null || y is null)
+            // One-side null
+            if (x == null || y == null)
                 return false;
-            // Otherwise, use EntProtoId of item to keep
+            // Otherwise, use EntProtoId of item
             return x.ID == y.ID;
         }
 
         public int GetHashCode(DroppableBorgItem obj)
         {
-            if (obj is null) return 0;
+            if (obj is null)
+                return 0;
             return obj.ID.GetHashCode();
         }
     }