feat(inventory): GrantAsync handles currency branches

Crystal/Rupy/RedEther/SpotCardPoint grants mutate ViewerCurrency in place
and emit post-state-total wire entries. Op log records the post-state for
later currency-collision resolution in CommitAsync.

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

SVSim.Database/Services/Inventory/InventoryTransaction.cs

@@ -17,6 +17,12 @@ internal sealed class InventoryTransaction : IInventoryTransaction
     public Viewer Viewer { get; }
     public bool IsFreeplay => _freeplay.Enabled;
 
+    private readonly List<InventoryOp> _ops = new();
+
+    internal abstract record InventoryOp;
+    internal sealed record SpendOp(SpendCurrency Currency, long Cost, long PostState) : InventoryOp;
+    internal sealed record GrantOp(UserGoodsType Type, long DetailId, int Num, int PostStateOrCount, bool IsCascade) : InventoryOp;
+
     public InventoryTransaction(
         SVSimDbContext db,
         IDbContextTransaction dbTx,
@@ -38,8 +44,41 @@ internal sealed class InventoryTransaction : IInventoryTransaction
     public Task<SpendResult> TryDebitAsync(UserGoodsType type, long detailId, int num, CancellationToken ct = default)
         => throw new NotImplementedException();
 
-    public Task<IReadOnlyList<GrantedReward>> GrantAsync(UserGoodsType type, long detailId, int num, CancellationToken ct = default)
+    public async Task<IReadOnlyList<GrantedReward>> GrantAsync(UserGoodsType type, long detailId, int num, CancellationToken ct = default)
-        => throw new NotImplementedException();
+    {
+        ThrowIfCommitted();
+
+        switch (type)
+        {
+            case UserGoodsType.Rupy:
+                Viewer.Currency.Rupees += (ulong)num;
+                var rupy = checked((int)Viewer.Currency.Rupees);
+                _ops.Add(new GrantOp(type, detailId, num, rupy, false));
+                return Single(type, detailId, rupy);
+
+            case UserGoodsType.Crystal:
+                Viewer.Currency.Crystals += (ulong)num;
+                var crystal = checked((int)Viewer.Currency.Crystals);
+                _ops.Add(new GrantOp(type, detailId, num, crystal, false));
+                return Single(type, detailId, crystal);
+
+            case UserGoodsType.RedEther:
+                Viewer.Currency.RedEther += (ulong)num;
+                var red = checked((int)Viewer.Currency.RedEther);
+                _ops.Add(new GrantOp(type, detailId, num, red, false));
+                return Single(type, detailId, red);
+
+            case UserGoodsType.SpotCardPoint:
+                Viewer.Currency.SpotPoints += (ulong)num;
+                var spot = checked((int)Viewer.Currency.SpotPoints);
+                _ops.Add(new GrantOp(type, detailId, num, spot, false));
+                return Single(type, detailId, spot);
+
+            default:
+                throw new NotImplementedException(
+                    $"UserGoodsType {type} grant lands in a subsequent task");
+        }
+    }
 
     public Task<int> BackfillCardCosmeticsAsync(CancellationToken ct = default)
         => throw new NotImplementedException();
@@ -51,6 +90,15 @@ internal sealed class InventoryTransaction : IInventoryTransaction
     public Task<InventoryCommitResult> CommitAsync(CancellationToken ct = default)
         => throw new NotImplementedException();
 
+    private static IReadOnlyList<GrantedReward> Single(UserGoodsType type, long id, int num)
+        => new[] { new GrantedReward((int)type, id, num) };
+
+    private void ThrowIfCommitted()
+    {
+        if (_committed)
+            throw new InvalidOperationException("Inventory transaction already committed");
+    }
+
     public async ValueTask DisposeAsync()
     {
         if (!_committed)

SVSim.UnitTests/Services/Inventory/InventoryGrantCurrencyTests.cs

@@ -0,0 +1,41 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.DependencyInjection;
+using SVSim.Database;
+using SVSim.Database.Enums;
+using SVSim.Database.Services.Inventory;
+using SVSim.UnitTests.Infrastructure;
+
+namespace SVSim.UnitTests.Services.Inventory;
+
+public class InventoryGrantCurrencyTests
+{
+    [TestCase(UserGoodsType.Rupy)]
+    [TestCase(UserGoodsType.Crystal)]
+    [TestCase(UserGoodsType.RedEther)]
+    [TestCase(UserGoodsType.SpotCardPoint)]
+    public async Task Grant_currency_adds_and_emits_post_state(UserGoodsType type)
+    {
+        using var factory = new SVSimTestFactory();
+        long viewerId = await factory.SeedViewerAsync();
+        using var scope = factory.Services.CreateScope();
+        var ctx = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+        var v = await ctx.Viewers.FirstAsync(x => x.Id == viewerId);
+        switch (type)
+        {
+            case UserGoodsType.Rupy: v.Currency.Rupees = 100; break;
+            case UserGoodsType.Crystal: v.Currency.Crystals = 100; break;
+            case UserGoodsType.RedEther: v.Currency.RedEther = 100; break;
+            case UserGoodsType.SpotCardPoint: v.Currency.SpotPoints = 100; break;
+        }
+        await ctx.SaveChangesAsync();
+
+        var inv = scope.ServiceProvider.GetRequiredService<IInventoryService>();
+        await using var tx = await inv.BeginAsync(viewerId);
+
+        var granted = await tx.GrantAsync(type, detailId: 0, num: 50);
+
+        Assert.That(granted, Has.Count.EqualTo(1));
+        Assert.That(granted[0].RewardType, Is.EqualTo((int)type));
+        Assert.That(granted[0].RewardNum, Is.EqualTo(150));
+    }
+}