diff --git a/SVSim.EmulatedEntrypoint/Controllers/AchievementController.cs b/SVSim.EmulatedEntrypoint/Controllers/AchievementController.cs
index 8c186b7..e345258 100644
--- a/SVSim.EmulatedEntrypoint/Controllers/AchievementController.cs
+++ b/SVSim.EmulatedEntrypoint/Controllers/AchievementController.cs
@@ -2,9 +2,8 @@ using Microsoft.AspNetCore.Mvc;
 using Microsoft.EntityFrameworkCore;
 using SVSim.Database;
 using SVSim.Database.Enums;
-using SVSim.Database.Models;
 using SVSim.Database.Repositories.Mission;
-using SVSim.Database.Services;
+using SVSim.Database.Services.Inventory;
 using SVSim.EmulatedEntrypoint.Models.Dtos.Achievement;
 using SVSim.EmulatedEntrypoint.Services;
 
@@ -22,20 +21,20 @@ public class AchievementController : SVSimController
     private readonly IMissionCatalogRepository _catalog;
     private readonly IViewerMissionStateService _state;
     private readonly IMissionAssembler _assembler;
-    private readonly RewardGrantService _grantService;
+    private readonly IInventoryService _inv;
 
     public AchievementController(
         SVSimDbContext db,
         IMissionCatalogRepository catalog,
         IViewerMissionStateService state,
         IMissionAssembler assembler,
-        RewardGrantService grantService)
+        IInventoryService inv)
     {
         _db = db;
         _catalog = catalog;
         _state = state;
         _assembler = assembler;
-        _grantService = grantService;
+        _inv = inv;
     }
 
     [HttpPost("receive_reward")]
@@ -44,21 +43,15 @@ public class AchievementController : SVSimController
     {
         if (!TryGetViewerId(out long viewerId)) return Unauthorized();
 
-        // Load viewer with all the collections RewardGrantService may need to mutate.
-        var viewer = await _db.Viewers
-            .Include(v => v.MissionData)
-            .Include(v => v.Currency)
-            .Include(v => v.Cards)
-            .Include(v => v.Items)
-            .Include(v => v.Sleeves)
-            .Include(v => v.Emblems)
-            .Include(v => v.Degrees)
-            .Include(v => v.LeaderSkins)
-            .Include(v => v.MyPageBackgrounds)
-            .AsSplitQuery()
-            .FirstAsync(v => v.Id == viewerId, ct);
+        // EnsureCurrentAsync needs a viewer id — use a lightweight pre-check load then
+        // materialize state before opening the inventory tx.
+        var viewerIdCheck = await _db.Viewers
+            .Where(v => v.Id == viewerId)
+            .Select(v => v.Id)
+            .FirstOrDefaultAsync(ct);
+        if (viewerIdCheck == 0) return Unauthorized();
 
-        await _state.EnsureCurrentAsync(viewer.Id, ct);
+        await _state.EnsureCurrentAsync(viewerId, ct);
         await _db.SaveChangesAsync(ct);
 
         // Re-read viewer's achievement for this type after state-service materialization.
@@ -75,9 +68,10 @@ public class AchievementController : SVSimController
             return Ok(new { result_code = FailureResultCode });
         }
 
-        // Grant via the canonical RewardGrantService primitive.
-        var granted = await _grantService.ApplyAsync(
-            viewer,
+        // Open inventory tx and grant via InventoryService.
+        await using var tx = await _inv.BeginAsync(viewerId, ct);
+
+        var granted = await tx.GrantAsync(
             (UserGoodsType)catalogRow.RewardType,
             catalogRow.RewardDetailId,
             catalogRow.RewardNumber,
@@ -99,9 +93,9 @@ public class AchievementController : SVSimController
         }
         ach.NowAchievedLevel = request.Level;
 
-        await _db.SaveChangesAsync(ct);
+        await tx.CommitAsync(ct);
 
-        var dto = await _assembler.BuildAsync(viewer, ct);
+        var dto = await _assembler.BuildAsync(tx.Viewer, ct);
         var resp = new AchievementReceiveRewardResponse
         {
             UserMissionList = dto.UserMissionList,