Add PopupPredictedCursor and fix doubled popups on vending machines (#36655)

* Add PopupCursorPredicted method

* Fix doubled popups on vending machine restock failures

* Rename to match existing pattern

Content.Client/Popups/PopupSystem.cs

@@ -173,6 +173,16 @@ namespace Content.Client.Popups
                 PopupCursor(message, type);
         }
 
+        public override void PopupPredictedCursor(string? message, ICommonSession recipient, PopupType type = PopupType.Small)
+        {
+            PopupCursor(message, recipient, type);
+        }
+
+        public override void PopupPredictedCursor(string? message, EntityUid recipient, PopupType type = PopupType.Small)
+        {
+            PopupCursor(message, recipient, type);
+        }
+
         public override void PopupCoordinates(string? message, EntityCoordinates coordinates, Filter filter, bool replayRecord, PopupType type = PopupType.Small)
         {
             PopupCoordinates(message, coordinates, type);

Content.Server/Popups/PopupSystem.cs

@@ -35,6 +35,16 @@ namespace Content.Server.Popups
                 RaiseNetworkEvent(new PopupCursorEvent(message, type), actor.PlayerSession);
         }
 
+        public override void PopupPredictedCursor(string? message, ICommonSession recipient, PopupType type = PopupType.Small)
+        {
+            // Do nothing, since the client already predicted the popup.
+        }
+
+        public override void PopupPredictedCursor(string? message, EntityUid recipient, PopupType type = PopupType.Small)
+        {
+            // Do nothing, since the client already predicted the popup.
+        }
+
         public override void PopupCoordinates(string? message, EntityCoordinates coordinates, Filter filter, bool replayRecord, PopupType type = PopupType.Small)
         {
             if (message == null)

Content.Shared/Popups/SharedPopupSystem.cs

@@ -32,6 +32,18 @@ namespace Content.Shared.Popups
         /// <param name="type">Used to customize how this popup should appear visually.</param>
         public abstract void PopupCursor(string? message, EntityUid recipient, PopupType type = PopupType.Small);
 
+        /// <summary>
+        /// Variant of <see cref="PopupCursor(string?, ICommonSession, PopupType)"/> for use with prediction.
+        /// The local client will show the popup to the recipient. Does nothing on the server.
+        /// </summary>
+        public abstract void PopupPredictedCursor(string? message, ICommonSession recipient, PopupType type = PopupType.Small);
+
+        /// <summary>
+        /// Variant of <see cref="PopupCursor(string?, EntityUid, PopupType)"/> for use with prediction.
+        /// The local client will show the popup to the recipient. Does nothing on the server.
+        /// </summary>
+        public abstract void PopupPredictedCursor(string? message, EntityUid recipient, PopupType type = PopupType.Small);
+
         /// <summary>
         ///     Shows a popup at a world location to every entity in PVS range.
         /// </summary>

Content.Shared/VendingMachines/SharedVendingMachineSystem.Restock.cs

@@ -17,7 +17,7 @@ public abstract partial class SharedVendingMachineSystem
     {
         if (!TryComp<WiresPanelComponent>(target, out var panel) || !panel.Open)
         {
-            Popup.PopupCursor(Loc.GetString("vending-machine-restock-needs-panel-open",
+            Popup.PopupPredictedCursor(Loc.GetString("vending-machine-restock-needs-panel-open",
                     ("this", uid),
                     ("user", user),
                     ("target", target)),
@@ -37,7 +37,7 @@ public abstract partial class SharedVendingMachineSystem
     {
         if (!component.CanRestock.Contains(machineComponent.PackPrototypeId))
         {
-            Popup.PopupCursor(Loc.GetString("vending-machine-restock-invalid-inventory", ("this", uid), ("user", user),
+            Popup.PopupPredictedCursor(Loc.GetString("vending-machine-restock-invalid-inventory", ("this", uid), ("user", user),
                 ("target", target)), user);
 
             return false;