refactor(gacha-point): route TryExchangeAsync through IInventoryTransaction

Change signature from (Viewer, packId, cardId) to (IInventoryTransaction, packId, cardId).
Drop RewardGrantService from GachaPointService ctor. PackController.ExchangeGachaPoint opens
tx with GachaPointBalances/Received extra includes, passes tx, commits on success.
Update GachaPointServiceTests to use inv.BeginAsync + tx pattern.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

SVSim.EmulatedEntrypoint/Controllers/PackController.cs

@@ -202,26 +202,18 @@ public class PackController : SVSimController
     {
         if (!TryGetViewerId(out long viewerId)) return Unauthorized();
 
-        // Load the viewer with the collections the service mutates (balances, received marker,
+        // Open inventory tx with extra includes for GachaPointBalances + GachaPointReceived
-        // cards, cosmetics). AsSplitQuery per project_ef_split_query memory.
+        // (needed by TryExchangeAsync to validate balance and already-received guard).
-        var viewer = await _db.Viewers
+        await using var tx = await _inv.BeginAsync(viewerId, configure: cfg => cfg
-            .Include(v => v.GachaPointBalances)
+            .WithInclude(v => v.GachaPointBalances)
-            .Include(v => v.GachaPointReceived)
+            .WithInclude(v => v.GachaPointReceived));
-            .Include(v => v.Cards)
-            .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);
 
         // Use odds_gacha_id (the seasonal pack id) — that's where the balance / received marker
         // live. Mirrors the GetGachaPointRewards fix.
-        var outcome = await _gachaPoint.TryExchangeAsync(viewer, request.OddsGachaId, request.CardId);
+        var outcome = await _gachaPoint.TryExchangeAsync(tx, request.OddsGachaId, request.CardId);
         if (!outcome.Success) return BadRequest(new { error = outcome.Error });
 
-        await _db.SaveChangesAsync();
+        await tx.CommitAsync();
 
         return new ExchangeGachaPointResponse
         {

SVSim.EmulatedEntrypoint/Services/GachaPointService.cs

@@ -5,6 +5,7 @@ using SVSim.Database.Enums;
 using SVSim.Database.Models;
 using SVSim.Database.Repositories.PackDrawTables;
 using SVSim.Database.Services;
+using SVSim.Database.Services.Inventory;
 using SVSim.EmulatedEntrypoint.Models.Dtos;
 
 namespace SVSim.EmulatedEntrypoint.Services;
@@ -13,13 +14,11 @@ public sealed class GachaPointService : IGachaPointService
 {
     private readonly SVSimDbContext _db;
     private readonly IPackDrawTableRepository _drawTables;
-    private readonly RewardGrantService _grants;
 
-    public GachaPointService(SVSimDbContext db, IPackDrawTableRepository drawTables, RewardGrantService grants)
+    public GachaPointService(SVSimDbContext db, IPackDrawTableRepository drawTables)
     {
         _db = db;
         _drawTables = drawTables;
-        _grants = grants;
     }
 
     public async Task<IReadOnlyList<GachaPointRewardDto>> GetRewardsAsync(int packId, long viewerId)
@@ -176,8 +175,9 @@ public sealed class GachaPointService : IGachaPointService
         }
     }
 
-    public async Task<ExchangeOutcome> TryExchangeAsync(Viewer viewer, int packId, long cardId)
+    public async Task<ExchangeOutcome> TryExchangeAsync(IInventoryTransaction tx, int packId, long cardId)
     {
+        var viewer = tx.Viewer;
         var pack = await _db.Packs.FirstOrDefaultAsync(p => p.Id == packId);
         if (pack?.GachaPointConfig is null)
             return ExchangeOutcome.Fail("pack_not_exchangeable");
@@ -206,23 +206,13 @@ public sealed class GachaPointService : IGachaPointService
             PackId = packId, CardId = cardId, ReceivedAt = DateTime.UtcNow,
         });
 
-        // Grant the card itself through RewardGrantService — its CardCosmeticReward cascade
+        // Grant the card via the inventory tx — its CardCosmeticReward cascade covers the
-        // covers the Emblem (standard legendary) or Skin+Emblem (leader) the catalog
+        // Emblem (standard legendary) or Skin+Emblem (leader). Convert at the wire boundary
-        // advertised. The catalog's reward_list is a wire-shape *display* (what the player
+        // so ExchangeOutcome still carries RewardListEntry for the controller response.
-        // sees on /pack/get_gacha_point_rewards) — the actual grant uses the canonical
+        var granted = await tx.GrantAsync(UserGoodsType.Card, cardId, 1);
-        // primitive per feedback_reward_grant_service. For leader-card exchanges the catalog
+        var rewardList = granted
-        // also advertises a synthetic Sleeve(=card_id) entry, but that's not in
+            .Select(g => new RewardListEntry { RewardType = g.RewardType, RewardId = g.RewardId, RewardNum = g.RewardNum })
-        // CardCosmeticRewards; if a capture ever shows leader exchanges granting a sleeve
+            .ToList();
-        // row, add that here. Today no leader exchange has been captured.
-        var granted = await _grants.ApplyAsync(viewer, UserGoodsType.Card, cardId, 1);
-        var rewardList = new List<RewardListEntry>();
-        foreach (var g in granted)
-        {
-            rewardList.Add(new RewardListEntry
-            {
-                RewardType = g.RewardType, RewardId = g.RewardId, RewardNum = g.RewardNum,
-            });
-        }
 
         return ExchangeOutcome.Ok(rewardList);
     }

SVSim.EmulatedEntrypoint/Services/IGachaPointService.cs

@@ -1,4 +1,5 @@
 using SVSim.Database.Models;
+using SVSim.Database.Services.Inventory;
 using SVSim.EmulatedEntrypoint.Models.Dtos;
 
 namespace SVSim.EmulatedEntrypoint.Services;
@@ -23,11 +24,14 @@ public interface IGachaPointService
     void Accrue(Viewer viewer, PackConfigEntry pack, PackChildGachaEntry child, int packNumber);
 
     /// <summary>
-    /// Validate + execute an exchange. Returns the grant outcome on success (reward_list
+    /// Validate + execute an exchange using the provided inventory transaction (which must
-    /// entries the controller will return in <see cref="Dtos.Responses.Pack.ExchangeGachaPointResponse"/>),
+    /// have <c>GachaPointBalances</c> and <c>GachaPointReceived</c> loaded on <c>tx.Viewer</c>
-    /// or a failure result describing why. Mutates the in-memory graph; caller saves.
+    /// via <see cref="IInventoryService.BeginAsync"/> extra includes). Grants the card via
+    /// the tx. Returns the grant outcome on success (reward_list entries already converted to
+    /// <see cref="RewardListEntry"/>), or a failure result describing why. Caller commits
+    /// the tx on success.
     /// </summary>
-    Task<ExchangeOutcome> TryExchangeAsync(Viewer viewer, int packId, long cardId);
+    Task<ExchangeOutcome> TryExchangeAsync(IInventoryTransaction tx, int packId, long cardId);
 }
 
 public sealed record ExchangeOutcome(bool Success, string? Error, IReadOnlyList<RewardListEntry> RewardList)

SVSim.UnitTests/Services/GachaPointServiceTests.cs

@@ -4,6 +4,7 @@ using NUnit.Framework;
 using SVSim.Database;
 using SVSim.Database.Enums;
 using SVSim.Database.Models;
+using SVSim.Database.Services.Inventory;
 using SVSim.EmulatedEntrypoint.Services;
 using SVSim.UnitTests.Infrastructure;
 
@@ -380,14 +381,17 @@ public class GachaPointServiceTests
 
         SeedPackWithOneLegendary(db, packId: 10008, threshold: 400);
 
-        var viewer = await db.Viewers
+        var viewer = await db.Viewers.Include(v => v.GachaPointBalances).FirstAsync(v => v.Id == viewerId);
-            .Include(v => v.GachaPointBalances)
-            .FirstAsync(v => v.Id == viewerId);
         viewer.GachaPointBalances.Add(new ViewerGachaPointBalance { PackId = 10008, Points = 399 });
         await db.SaveChangesAsync();
 
         var svc = scope.ServiceProvider.GetRequiredService<IGachaPointService>();
-        var outcome = await svc.TryExchangeAsync(viewer, 10008, 108041010);
+        var inv = scope.ServiceProvider.GetRequiredService<IInventoryService>();
+        await using var tx = await inv.BeginAsync(viewerId, configure: cfg => cfg
+            .WithInclude(v => v.GachaPointBalances)
+            .WithInclude(v => v.GachaPointReceived));
+
+        var outcome = await svc.TryExchangeAsync(tx, 10008, 108041010);
 
         Assert.That(outcome.Success, Is.False);
         Assert.That(outcome.Error, Is.EqualTo("insufficient_gacha_points"));
@@ -403,14 +407,17 @@ public class GachaPointServiceTests
 
         SeedPackWithOneLegendary(db, packId: 10008, threshold: 400);
 
-        var viewer = await db.Viewers
+        var viewer = await db.Viewers.Include(v => v.GachaPointBalances).FirstAsync(v => v.Id == viewerId);
-            .Include(v => v.GachaPointBalances)
-            .FirstAsync(v => v.Id == viewerId);
         viewer.GachaPointBalances.Add(new ViewerGachaPointBalance { PackId = 10008, Points = 400 });
         await db.SaveChangesAsync();
 
         var svc = scope.ServiceProvider.GetRequiredService<IGachaPointService>();
-        var outcome = await svc.TryExchangeAsync(viewer, 10008, cardId: 999999999);  // not in pool
+        var inv = scope.ServiceProvider.GetRequiredService<IInventoryService>();
+        await using var tx = await inv.BeginAsync(viewerId, configure: cfg => cfg
+            .WithInclude(v => v.GachaPointBalances)
+            .WithInclude(v => v.GachaPointReceived));
+
+        var outcome = await svc.TryExchangeAsync(tx, 10008, cardId: 999999999);  // not in pool
 
         Assert.That(outcome.Success, Is.False);
         Assert.That(outcome.Error, Is.EqualTo("card_not_exchangeable"));
@@ -438,7 +445,12 @@ public class GachaPointServiceTests
         await db.SaveChangesAsync();
 
         var svc = scope.ServiceProvider.GetRequiredService<IGachaPointService>();
-        var outcome = await svc.TryExchangeAsync(viewer, 10008, 108041010);
+        var inv = scope.ServiceProvider.GetRequiredService<IInventoryService>();
+        await using var tx = await inv.BeginAsync(viewerId, configure: cfg => cfg
+            .WithInclude(v => v.GachaPointBalances)
+            .WithInclude(v => v.GachaPointReceived));
+
+        var outcome = await svc.TryExchangeAsync(tx, 10008, 108041010);
 
         Assert.That(outcome.Success, Is.False);
         Assert.That(outcome.Error, Is.EqualTo("already_received"));
@@ -454,29 +466,31 @@ public class GachaPointServiceTests
 
         SeedPackWithOneLegendary(db, packId: 10008, threshold: 400);
 
-        var viewer = await db.Viewers
+        var preViewer = await db.Viewers
             .Include(v => v.GachaPointBalances)
-            .Include(v => v.GachaPointReceived)
-            .Include(v => v.Cards)
-            .Include(v => v.Emblems)
             .FirstAsync(v => v.Id == viewerId);
-        viewer.GachaPointBalances.Add(new ViewerGachaPointBalance { PackId = 10008, Points = 500 });
+        preViewer.GachaPointBalances.Add(new ViewerGachaPointBalance { PackId = 10008, Points = 500 });
         await db.SaveChangesAsync();
 
         var svc = scope.ServiceProvider.GetRequiredService<IGachaPointService>();
-        var outcome = await svc.TryExchangeAsync(viewer, 10008, 108041010);
+        var inv = scope.ServiceProvider.GetRequiredService<IInventoryService>();
-        await db.SaveChangesAsync();
+        await using var tx = await inv.BeginAsync(viewerId, configure: cfg => cfg
+            .WithInclude(v => v.GachaPointBalances)
+            .WithInclude(v => v.GachaPointReceived));
 
+        var outcome = await svc.TryExchangeAsync(tx, 10008, 108041010);
         Assert.That(outcome.Success, Is.True);
 
-        // Balance debited.
+        await tx.CommitAsync();
-        Assert.That(viewer.GachaPointBalances.Single().Points, Is.EqualTo(100));
+
+        // Balance debited (check via tx.Viewer which is tracked).
+        Assert.That(tx.Viewer.GachaPointBalances.Single().Points, Is.EqualTo(100));
 
         // Marker written.
-        Assert.That(viewer.GachaPointReceived
+        Assert.That(tx.Viewer.GachaPointReceived
             .Any(r => r.PackId == 10008 && r.CardId == 108041010), Is.True);
 
-        // Reward list non-empty: at minimum the card grant and the gacha-point post-state entry.
+        // Reward list non-empty: at minimum the card grant.
         Assert.That(outcome.RewardList, Is.Not.Empty);
         Assert.That(outcome.RewardList.Any(r => r.RewardType == (int)UserGoodsType.Card && r.RewardId == 108041010),
             Is.True, "card grant missing");