diff --git a/SVSim.EmulatedEntrypoint/Controllers/SpotCardExchangeController.cs b/SVSim.EmulatedEntrypoint/Controllers/SpotCardExchangeController.cs
index 584cbc7..d5d8ec9 100644
--- a/SVSim.EmulatedEntrypoint/Controllers/SpotCardExchangeController.cs
+++ b/SVSim.EmulatedEntrypoint/Controllers/SpotCardExchangeController.cs
@@ -30,12 +30,14 @@ public class SpotCardExchangeController : SVSimController
     private readonly SVSimDbContext _db;
     private readonly RewardGrantService _rewards;
     private readonly TimeProvider _time;
+    private readonly ICurrencySpendService _spend;
 
-    public SpotCardExchangeController(SVSimDbContext db, RewardGrantService rewards, TimeProvider time)
+    public SpotCardExchangeController(SVSimDbContext db, RewardGrantService rewards, TimeProvider time, ICurrencySpendService spend)
     {
         _db = db;
         _rewards = rewards;
         _time = time;
+        _spend = spend;
     }
 
     [HttpPost("top")]
@@ -131,14 +133,14 @@ public class SpotCardExchangeController : SVSimController
         // Debit spot points. Client-supplied exchange_point isn't authoritative — server uses
         // catalog price. Mirroring the build_deck/sleeve convention: post-state currency entry
         // first, then grants.
-        if (viewer.Currency.SpotPoints < (ulong)entry.ExchangePoint)
+        var spotRes = await _spend.TrySpendAsync(viewer, SpendCurrency.SpotPoint, entry.ExchangePoint);
+        if (!spotRes.Success)
             return BadRequest(new { error = "insufficient_spot_points" });
-        viewer.Currency.SpotPoints -= (ulong)entry.ExchangePoint;
         rewardList.Add(new RewardListEntry
         {
             RewardType = (int)UserGoodsType.SpotCardPoint,
             RewardId = 0,
-            RewardNum = checked((int)viewer.Currency.SpotPoints),
+            RewardNum = checked((int)spotRes.PostStateTotal),
         });
 
         // Grant the card itself via the existing card dispatcher (handles cosmetic cascade).