diff --git a/SVSim.EmulatedEntrypoint/Controllers/ItemPurchaseController.cs b/SVSim.EmulatedEntrypoint/Controllers/ItemPurchaseController.cs
index 7b1d3b4..900dcd6 100644
--- a/SVSim.EmulatedEntrypoint/Controllers/ItemPurchaseController.cs
+++ b/SVSim.EmulatedEntrypoint/Controllers/ItemPurchaseController.cs
@@ -4,6 +4,7 @@ using SVSim.Database;
 using SVSim.Database.Enums;
 using SVSim.Database.Models;
 using SVSim.Database.Services;
+using SVSim.Database.Services.Inventory;
 using SVSim.EmulatedEntrypoint.Models.Dtos;
 using SVSim.EmulatedEntrypoint.Models.Dtos.Requests;
 using SVSim.EmulatedEntrypoint.Models.Dtos.Requests.ItemPurchase;
@@ -21,16 +22,14 @@ namespace SVSim.EmulatedEntrypoint.Controllers;
 public class ItemPurchaseController : SVSimController
 {
     private readonly SVSimDbContext _db;
-    private readonly RewardGrantService _rewards;
+    private readonly IInventoryService _inv;
     private readonly TimeProvider _time;
-    private readonly ICurrencySpendService _spend;
 
-    public ItemPurchaseController(SVSimDbContext db, RewardGrantService rewards, TimeProvider time, ICurrencySpendService spend)
+    public ItemPurchaseController(SVSimDbContext db, IInventoryService inv, TimeProvider time)
     {
         _db = db;
-        _rewards = rewards;
+        _inv = inv;
         _time = time;
-        _spend = spend;
     }
 
     [HttpPost("info")]
@@ -115,28 +114,17 @@ public class ItemPurchaseController : SVSimController
         if (rest <= 0)
             return BadRequest(new { error = "sold_out" });
 
-        var viewer = await LoadViewerGraphAsync(viewerId);
-        var rewardList = new List<RewardListEntry>();
+        await using var tx = await _inv.BeginAsync(viewerId, HttpContext.RequestAborted);
 
-        // Debit the require side. RewardGrantService is grant-only, so handle this inline.
-        var debit = await TryDebit(viewer, (UserGoodsType)entry.RequireItemType, entry.RequireItemId, entry.RequireItemNum);
-        if (debit.Error is not null) return BadRequest(new { error = debit.Error });
-        if (debit.PostState is not null) rewardList.Add(debit.PostState);
+        // Debit the require side via the tx.
+        var debit = await tx.TryDebitAsync(
+            (UserGoodsType)entry.RequireItemType, entry.RequireItemId, entry.RequireItemNum);
+        if (!debit.Success) return BadRequest(new { error = MapDebitError(entry.RequireItemType) });
 
-        // Grant the purchase side through the central dispatcher.
-        var granted = await _rewards.ApplyAsync(viewer,
-            (UserGoodsType)entry.PurchaseItemType, entry.PurchaseItemId, entry.PurchaseItemNum);
-        foreach (var g in granted)
-        {
-            rewardList.Add(new RewardListEntry
-            {
-                RewardType = g.RewardType,
-                RewardId = g.RewardId,
-                RewardNum = g.RewardNum,
-            });
-        }
+        // Grant the purchase side.
+        await tx.GrantAsync((UserGoodsType)entry.PurchaseItemType, entry.PurchaseItemId, entry.PurchaseItemNum);
 
-        // Increment the per-period counter.
+        // Increment the per-period counter (tracked via _db, outside the inventory tx).
         if (counter is null)
         {
             _db.ViewerEventCounters.Add(new ViewerEventCounter
@@ -151,52 +139,27 @@ public class ItemPurchaseController : SVSimController
         {
             counter.Count++;
         }
-
         await _db.SaveChangesAsync();
 
-        return new ItemPurchasePurchaseResponse { RewardList = rewardList };
-    }
+        var result = await tx.CommitAsync(HttpContext.RequestAborted);
 
-    /// <summary>
-    /// Debit <paramref name="num"/> of (<paramref name="type"/>, <paramref name="detailId"/>)
-    /// from the viewer, returning a post-state-aware <see cref="RewardListEntry"/> the client
-    /// uses to refresh its cached count. Returns an error string on insufficient balance.
-    /// </summary>
-    private async Task<(RewardListEntry? PostState, string? Error)> TryDebit(
-        Viewer viewer, UserGoodsType type, long detailId, int num)
-    {
-        switch (type)
+        return new ItemPurchasePurchaseResponse
         {
-            case UserGoodsType.RedEther:
-            {
-                var r = await _spend.TrySpendAsync(viewer, SpendCurrency.RedEther, num);
-                if (!r.Success) return (null, "insufficient_red_ether");
-                return (new RewardListEntry { RewardType = 1, RewardId = 0, RewardNum = (int)r.PostStateTotal }, null);
-            }
-            case UserGoodsType.Crystal:
-            {
-                var r = await _spend.TrySpendAsync(viewer, SpendCurrency.Crystal, num);
-                if (!r.Success) return (null, "insufficient_crystals");
-                return (new RewardListEntry { RewardType = 2, RewardId = 0, RewardNum = (int)r.PostStateTotal }, null);
-            }
-            case UserGoodsType.Rupy:
-            {
-                var r = await _spend.TrySpendAsync(viewer, SpendCurrency.Rupee, num);
-                if (!r.Success) return (null, "insufficient_rupees");
-                return (new RewardListEntry { RewardType = 9, RewardId = 0, RewardNum = (int)r.PostStateTotal }, null);
-            }
-            case UserGoodsType.Item:
-                var owned = viewer.Items.FirstOrDefault(i => i.Item.Id == (int)detailId);
-                if (owned is null || owned.Count < num)
-                    return (null, "insufficient_item");
-                owned.Count -= num;
-                return (new RewardListEntry { RewardType = 4, RewardId = detailId, RewardNum = owned.Count }, null);
-
-            default:
-                return (null, $"debit_type_not_supported:{type}");
-        }
+            RewardList = result.RewardList
+                .Select(g => new RewardListEntry { RewardType = g.RewardType, RewardId = g.RewardId, RewardNum = g.RewardNum })
+                .ToList(),
+        };
     }
 
+    private static string MapDebitError(int requireType) => requireType switch
+    {
+        (int)UserGoodsType.RedEther => "insufficient_red_ether",
+        (int)UserGoodsType.Crystal => "insufficient_crystals",
+        (int)UserGoodsType.Rupy => "insufficient_rupees",
+        (int)UserGoodsType.Item => "insufficient_item",
+        _ => "debit_type_not_supported",
+    };
+
     private static string CounterKey(int purchaseId) => $"item_purchase:{purchaseId}";
 
     private static int CounterCount(List<ViewerEventCounter> counters, ItemPurchaseCatalogEntry entry, string monthKey)
@@ -204,15 +167,4 @@ public class ItemPurchaseController : SVSimController
         var period = entry.IsMonthlyReset ? monthKey : JstPeriod.AllTime;
         return counters.FirstOrDefault(c => c.EventKey == CounterKey(entry.Id) && c.Period == period)?.Count ?? 0;
     }
-
-    private Task<Viewer> LoadViewerGraphAsync(long viewerId) => _db.Viewers
-        .Include(v => v.Items).ThenInclude(i => i.Item)
-        .Include(v => v.Cards).ThenInclude(c => c.Card)
-        .Include(v => v.Sleeves)
-        .Include(v => v.Emblems)
-        .Include(v => v.LeaderSkins)
-        .Include(v => v.Degrees)
-        .Include(v => v.MyPageBackgrounds)
-        .AsSplitQuery()
-        .FirstAsync(v => v.Id == viewerId);
 }