diff --git a/SVSim.UnitTests/Repositories/CardInventoryRepositoryTests.cs b/SVSim.UnitTests/Repositories/CardInventoryRepositoryTests.cs
index 01b2cf8..a907b31 100644
--- a/SVSim.UnitTests/Repositories/CardInventoryRepositoryTests.cs
+++ b/SVSim.UnitTests/Repositories/CardInventoryRepositoryTests.cs
@@ -2,6 +2,7 @@ using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.DependencyInjection;
 using SVSim.Database;
 using SVSim.Database.Enums;
+using SVSim.Database.Models;
 using SVSim.Database.Repositories.Card;
 using SVSim.UnitTests.Infrastructure;
 
@@ -311,4 +312,206 @@ public class CardInventoryRepositoryTests
         Assert.That(viewer.Currency.RedEther, Is.EqualTo(800UL));
         Assert.That(viewer.Cards.First(c => c.Card.Id == 10001001L).Count, Is.EqualTo(1));
     }
+
+    [Test]
+    public async Task Create_batch_charges_sum_and_grants_each_card()
+    {
+        using var factory = new SVSimTestFactory();
+        long viewerId = await factory.SeedViewerAsync();
+        await factory.SeedOwnedCardAsync(viewerId, cardId: 10001001L, count: 0, craftCost: 200);
+        await factory.SeedOwnedCardAsync(viewerId, cardId: 10001002L, count: 0, craftCost: 800);
+        await factory.SetRedEtherAsync(viewerId, 5_000UL);
+
+        using var scope = factory.Services.CreateScope();
+        var repo = scope.ServiceProvider.GetRequiredService<ICardInventoryRepository>();
+
+        var outcome = await repo.CreateCards(viewerId, new Dictionary<long, int>
+        {
+            { 10001001L, 2 },
+            { 10001002L, 1 },
+        });
+
+        Assert.That(outcome.IsSuccess, Is.True);
+        // 2 * 200 + 1 * 800 = 1200 → 5000 - 1200 = 3800
+        Assert.That(outcome.Result!.NewRedEtherTotal, Is.EqualTo(3_800UL));
+
+        var grants = outcome.Result!.Grants;
+        Assert.That(grants.Any(g => g.RewardId == 10001001L && g.RewardNum == 2), Is.True);
+        Assert.That(grants.Any(g => g.RewardId == 10001002L && g.RewardNum == 1), Is.True);
+    }
+
+    [Test]
+    public async Task Create_rejects_unknown_card_without_mutation()
+    {
+        using var factory = new SVSimTestFactory();
+        long viewerId = await factory.SeedViewerAsync();
+        await factory.SetRedEtherAsync(viewerId, 1_000UL);
+
+        using var scope = factory.Services.CreateScope();
+        var repo = scope.ServiceProvider.GetRequiredService<ICardInventoryRepository>();
+
+        var outcome = await repo.CreateCards(viewerId, new Dictionary<long, int> { { 99_999_999L, 1 } });
+
+        Assert.That(outcome.IsSuccess, Is.False);
+        Assert.That(outcome.Error, Is.EqualTo(CreateError.UnknownCard));
+
+        var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+        var viewer = await db.Viewers.FirstAsync(v => v.Id == viewerId);
+        Assert.That(viewer.Currency.RedEther, Is.EqualTo(1_000UL), "no debit on rejection");
+    }
+
+    [Test]
+    public async Task Create_rejects_not_craftable_card_without_mutation()
+    {
+        using var factory = new SVSimTestFactory();
+        long viewerId = await factory.SeedViewerAsync();
+        // craftCost=0 mirrors IsNotCraftDestruct on basic/token cards
+        await factory.SeedOwnedCardAsync(viewerId, cardId: 10001001L, count: 0, craftCost: 0, dustReward: 0);
+        await factory.SetRedEtherAsync(viewerId, 1_000UL);
+
+        using var scope = factory.Services.CreateScope();
+        var repo = scope.ServiceProvider.GetRequiredService<ICardInventoryRepository>();
+
+        var outcome = await repo.CreateCards(viewerId, new Dictionary<long, int> { { 10001001L, 1 } });
+
+        Assert.That(outcome.IsSuccess, Is.False);
+        Assert.That(outcome.Error, Is.EqualTo(CreateError.NotCraftable));
+
+        var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+        var viewer = await db.Viewers.FirstAsync(v => v.Id == viewerId);
+        Assert.That(viewer.Currency.RedEther, Is.EqualTo(1_000UL));
+    }
+
+    [Test]
+    public async Task Create_rejects_when_would_exceed_max_copies()
+    {
+        using var factory = new SVSimTestFactory();
+        long viewerId = await factory.SeedViewerAsync();
+        // Viewer already owns 2 copies — crafting 2 more would push to 4, exceeding MaxCopies=3.
+        await factory.SeedOwnedCardAsync(viewerId, cardId: 10001001L, count: 2, craftCost: 200);
+        await factory.SetRedEtherAsync(viewerId, 1_000UL);
+
+        using var scope = factory.Services.CreateScope();
+        var repo = scope.ServiceProvider.GetRequiredService<ICardInventoryRepository>();
+
+        var outcome = await repo.CreateCards(viewerId, new Dictionary<long, int> { { 10001001L, 2 } });
+
+        Assert.That(outcome.IsSuccess, Is.False);
+        Assert.That(outcome.Error, Is.EqualTo(CreateError.WouldExceedMaxCopies));
+    }
+
+    [Test]
+    public async Task Create_at_boundary_2_to_3_succeeds()
+    {
+        using var factory = new SVSimTestFactory();
+        long viewerId = await factory.SeedViewerAsync();
+        await factory.SeedOwnedCardAsync(viewerId, cardId: 10001001L, count: 2, craftCost: 200);
+        await factory.SetRedEtherAsync(viewerId, 1_000UL);
+
+        using var scope = factory.Services.CreateScope();
+        var repo = scope.ServiceProvider.GetRequiredService<ICardInventoryRepository>();
+
+        // 2 + 1 = 3 = MaxCopies — must succeed
+        var outcome = await repo.CreateCards(viewerId, new Dictionary<long, int> { { 10001001L, 1 } });
+
+        Assert.That(outcome.IsSuccess, Is.True);
+
+        var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+        var viewer = await db.Viewers.Include(v => v.Cards).ThenInclude(c => c.Card).FirstAsync(v => v.Id == viewerId);
+        Assert.That(viewer.Cards.First(c => c.Card.Id == 10001001L).Count, Is.EqualTo(3));
+    }
+
+    [Test]
+    public async Task Create_rejects_insufficient_vials_without_mutation()
+    {
+        using var factory = new SVSimTestFactory();
+        long viewerId = await factory.SeedViewerAsync();
+        await factory.SeedOwnedCardAsync(viewerId, cardId: 10001001L, count: 0, craftCost: 200);
+        await factory.SetRedEtherAsync(viewerId, 199UL);   // one less than needed
+
+        using var scope = factory.Services.CreateScope();
+        var repo = scope.ServiceProvider.GetRequiredService<ICardInventoryRepository>();
+
+        var outcome = await repo.CreateCards(viewerId, new Dictionary<long, int> { { 10001001L, 1 } });
+
+        Assert.That(outcome.IsSuccess, Is.False);
+        Assert.That(outcome.Error, Is.EqualTo(CreateError.InsufficientVials));
+
+        var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+        var viewer = await db.Viewers.Include(v => v.Cards).ThenInclude(c => c.Card).FirstAsync(v => v.Id == viewerId);
+        Assert.That(viewer.Currency.RedEther, Is.EqualTo(199UL), "no debit on rejection");
+        Assert.That(viewer.Cards.First(c => c.Card.Id == 10001001L).Count, Is.EqualTo(0), "no grant on rejection");
+    }
+
+    [Test]
+    public async Task Create_validates_full_batch_before_mutating()
+    {
+        using var factory = new SVSimTestFactory();
+        long viewerId = await factory.SeedViewerAsync();
+        await factory.SeedOwnedCardAsync(viewerId, cardId: 10001001L, count: 0, craftCost: 200);
+        // Second card has count=3 already — adding any would exceed MaxCopies
+        await factory.SeedOwnedCardAsync(viewerId, cardId: 10001002L, count: 3, craftCost: 200);
+        await factory.SetRedEtherAsync(viewerId, 1_000UL);
+
+        using var scope = factory.Services.CreateScope();
+        var repo = scope.ServiceProvider.GetRequiredService<ICardInventoryRepository>();
+
+        var outcome = await repo.CreateCards(viewerId, new Dictionary<long, int>
+        {
+            { 10001001L, 1 },   // would-be valid
+            { 10001002L, 1 },   // would push to 4 — fails validation
+        });
+
+        Assert.That(outcome.IsSuccess, Is.False);
+        Assert.That(outcome.Error, Is.EqualTo(CreateError.WouldExceedMaxCopies));
+
+        var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+        var viewer = await db.Viewers.Include(v => v.Cards).ThenInclude(c => c.Card).FirstAsync(v => v.Id == viewerId);
+        Assert.That(viewer.Currency.RedEther, Is.EqualTo(1_000UL), "no debit when batch fails");
+        Assert.That(viewer.Cards.First(c => c.Card.Id == 10001001L).Count, Is.EqualTo(0), "valid card untouched");
+    }
+
+    [Test]
+    public async Task Create_first_time_owner_triggers_cosmetic_cascade()
+    {
+        using var factory = new SVSimTestFactory();
+        long viewerId = await factory.SeedViewerAsync();
+        using var scope = factory.Services.CreateScope();
+        var ctx = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+
+        // Set up a card with a cosmetic-cascade row pointing at a Skin the viewer doesn't own.
+        // Use ids outside the seeded 10001001–10001003 range so the cascade can't accidentally
+        // pick up unrelated rows.
+        const long cardId = 999_003_010L;
+        const long skinId = 999_003_011L;
+        ctx.Cards.Add(new ShadowverseCardEntry
+        {
+            Id = cardId, Name = "CreateCascadeCard", Rarity = Rarity.Gold,
+            CollectionInfo = new CardCollectionInfo { CraftCost = 800, DustReward = 200 },
+        });
+        ctx.LeaderSkins.Add(new LeaderSkinEntry { Id = (int)skinId, Name = "CreateCascadeSkin" });
+        ctx.CardCosmeticRewards.Add(new CardCosmeticReward
+        {
+            CardId = cardId, Type = CosmeticType.Skin, CosmeticId = skinId, Quantity = 1,
+        });
+        await ctx.SaveChangesAsync();
+
+        // Give the viewer enough RedEther in a separate scope so the helper's reset doesn't fire.
+        await factory.SetRedEtherAsync(viewerId, 1_000UL);
+
+        var repo = scope.ServiceProvider.GetRequiredService<ICardInventoryRepository>();
+        var outcome = await repo.CreateCards(viewerId, new Dictionary<long, int> { { cardId, 1 } });
+
+        Assert.That(outcome.IsSuccess, Is.True);
+
+        var grants = outcome.Result!.Grants;
+        // One Card grant + one Skin cascade grant
+        Assert.That(grants.Any(g => g.RewardType == (int)UserGoodsType.Card && g.RewardId == cardId), Is.True);
+        Assert.That(grants.Any(g => g.RewardType == (int)UserGoodsType.Skin && g.RewardId == skinId), Is.True);
+
+        var viewer = await ctx.Viewers
+            .Include(v => v.LeaderSkins)
+            .FirstAsync(v => v.Id == viewerId);
+        Assert.That(viewer.LeaderSkins.Any(s => s.Id == (int)skinId), Is.True, "cascade actually granted the skin");
+    }
 }