diff --git a/SVSim.Database/Services/IViewerEntitlements.cs b/SVSim.Database/Services/IViewerEntitlements.cs
index 1a3ba83..fd5d23d 100644
--- a/SVSim.Database/Services/IViewerEntitlements.cs
+++ b/SVSim.Database/Services/IViewerEntitlements.cs
@@ -8,6 +8,14 @@ namespace SVSim.Database.Services;
 /// Freeplay flag; all freeplay read-side behavior lives here. See
 /// docs/superpowers/specs/2026-05-29-freeplay-mode-design.md.
 /// </summary>
+/// <remarks>
+/// <b>Include precondition:</b> methods that inspect the viewer's collections require the
+/// viewer to have been loaded with <c>.Include(v =&gt; v.Cards).ThenInclude(c =&gt; c.Card)</c>
+/// and the cosmetic collections
+/// (<c>Sleeves</c>, <c>Emblems</c>, <c>Degrees</c>, <c>LeaderSkins</c>, <c>MyPageBackgrounds</c>)
+/// included. Without those includes the EF owned-collection nav refs are null or zero-filled
+/// (see the EF owned-collection nav-include pitfall in MEMORY.md).
+/// </remarks>
 public interface IViewerEntitlements
 {
     /// <summary>True when the global Freeplay config section is enabled.</summary>
diff --git a/SVSim.UnitTests/Services/ViewerEntitlementsTests.cs b/SVSim.UnitTests/Services/ViewerEntitlementsTests.cs
index 7fde5fd..91665a0 100644
--- a/SVSim.UnitTests/Services/ViewerEntitlementsTests.cs
+++ b/SVSim.UnitTests/Services/ViewerEntitlementsTests.cs
@@ -96,4 +96,173 @@ public class ViewerEntitlementsTests
         Assert.That(ent.OwnsCard(viewer, 99_999_999L), Is.True);
         Assert.That(ent.OwnsCosmetic(viewer, CosmeticType.Skin, 99_999), Is.True);
     }
+
+    // -------------------------------------------------------------------------
+    // EffectiveOwnedCardsAsync
+    // -------------------------------------------------------------------------
+
+    [Test]
+    public async Task EffectiveOwnedCards_freeplay_on_returns_all_collectible_cards_at_card_copies()
+    {
+        using var factory = new SVSimTestFactory();
+        long viewerId = await factory.SeedViewerAsync();
+        // Seed one collectible card owned by this viewer (gives it a CollectionInfo).
+        await factory.SeedOwnedCardAsync(viewerId, 50001001L, count: 1);
+
+        using var scope = factory.Services.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+        SetFreeplayEnabled(db, enabled: true, cardCopies: 3);
+
+        var viewer = await db.Viewers
+            .Include(v => v.Cards).ThenInclude(c => c.Card)
+            .FirstAsync(v => v.Id == viewerId);
+
+        var ent = Build(scope);
+        var result = await ent.EffectiveOwnedCardsAsync(viewer);
+
+        // Freeplay returns the whole collectible catalog — card 50001001 must be present.
+        Assert.That(result.Any(e => e.Card.Id == 50001001L), Is.True,
+            "seeded collectible card must appear in freeplay result");
+
+        // Every returned entry must have Count == CardCopies (3).
+        Assert.That(result.All(e => e.Count == 3), Is.True,
+            "every freeplay entry should have Count == CardCopies (3)");
+
+        // The full set == every collectible card in the DB.
+        int collectibleCount = db.Cards.Count(c => c.CollectionInfo != null);
+        Assert.That(result.Count, Is.EqualTo(collectibleCount),
+            "freeplay result should contain exactly all collectible cards");
+    }
+
+    [Test]
+    public async Task EffectiveOwnedCards_freeplay_off_returns_only_owned()
+    {
+        using var factory = new SVSimTestFactory();
+        long viewerId = await factory.SeedViewerAsync();
+        // Seed card 50001002 owned at count 2.
+        await factory.SeedOwnedCardAsync(viewerId, 50001002L, count: 2);
+
+        // Seed a second collectible card (50001003) NOT owned by the viewer — insert card row
+        // only (with CollectionInfo so it's collectible) but do not link it to the viewer.
+        using (var setupScope = factory.Services.CreateScope())
+        {
+            var setupDb = setupScope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+            if (!setupDb.Cards.Any(c => c.Id == 50001003L))
+            {
+                setupDb.Cards.Add(new ShadowverseCardEntry
+                {
+                    Id = 50001003L,
+                    Name = "UnownedCollectible",
+                    Rarity = SVSim.Database.Enums.Rarity.Bronze,
+                    CollectionInfo = new SVSim.Database.Models.CardCollectionInfo { CraftCost = 200, DustReward = 50 },
+                });
+                await setupDb.SaveChangesAsync();
+            }
+        }
+
+        using var scope = factory.Services.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+        // Freeplay is off by default — no mutation needed.
+
+        var viewer = await db.Viewers
+            .Include(v => v.Cards).ThenInclude(c => c.Card)
+            .FirstAsync(v => v.Id == viewerId);
+
+        var ent = Build(scope);
+        var result = await ent.EffectiveOwnedCardsAsync(viewer);
+
+        // The owned card must be present at the right count.
+        var owned = result.FirstOrDefault(e => e.Card.Id == 50001002L);
+        Assert.That(owned, Is.Not.Null, "owned card should appear in result");
+        Assert.That(owned!.Count, Is.EqualTo(2));
+
+        // The unowned collectible card must NOT appear.
+        Assert.That(result.Any(e => e.Card.Id == 50001003L), Is.False,
+            "card not owned by viewer must not appear when freeplay is off");
+    }
+
+    // -------------------------------------------------------------------------
+    // EffectiveCosmeticsAsync
+    // -------------------------------------------------------------------------
+
+    [Test]
+    public async Task EffectiveCosmetics_leader_skins_always_full_catalog_owned_set_differs()
+    {
+        using var factory = new SVSimTestFactory();
+        long viewerId = await factory.SeedViewerAsync();
+
+        // --- freeplay OFF: fresh viewer owns no cosmetics ---
+        {
+            using var scope = factory.Services.CreateScope();
+            var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+            // Freeplay off by default.
+
+            var viewer = await db.Viewers
+                .Include(v => v.LeaderSkins)
+                .Include(v => v.Sleeves)
+                .Include(v => v.Emblems)
+                .Include(v => v.Degrees)
+                .Include(v => v.MyPageBackgrounds)
+                .FirstAsync(v => v.Id == viewerId);
+
+            var ent = Build(scope);
+            var cosmetics = await ent.EffectiveCosmeticsAsync(viewer);
+
+            int masterSkinCount = db.LeaderSkins.Count();
+            Assert.That(masterSkinCount, Is.GreaterThan(0),
+                "leaderskins.csv must have been imported — master table must be non-empty");
+            Assert.That(cosmetics.AllLeaderSkins.Count, Is.EqualTo(masterSkinCount),
+                "AllLeaderSkins should always be the full catalog regardless of freeplay");
+
+            // A fresh viewer owns one default skin per class (granted at registration).
+            // Assert the owned set matches what the viewer actually has — don't assume empty.
+            var expectedOwnedSkinIds = viewer.LeaderSkins.Select(s => s.Id).ToHashSet();
+            Assert.That(cosmetics.OwnedLeaderSkinIds, Is.EquivalentTo(expectedOwnedSkinIds),
+                "OwnedLeaderSkinIds should match the viewer's actual owned skins when freeplay is off");
+
+            // OwnedLeaderSkinIds must be a strict subset of AllLeaderSkins (not all of them).
+            Assert.That(cosmetics.OwnedLeaderSkinIds.Count, Is.LessThan(masterSkinCount),
+                "fresh viewer should own fewer skins than the full catalog");
+
+            // The four id-lists reflect what the viewer actually owns.
+            Assert.That(cosmetics.SleeveIds.Count, Is.EqualTo(viewer.Sleeves.Count));
+            Assert.That(cosmetics.EmblemIds.Count, Is.EqualTo(viewer.Emblems.Count));
+            Assert.That(cosmetics.DegreeIds.Count, Is.EqualTo(viewer.Degrees.Count));
+            Assert.That(cosmetics.MyPageBackgroundIds.Count, Is.EqualTo(viewer.MyPageBackgrounds.Count));
+        }
+
+        // --- freeplay ON: all catalogs become owned ---
+        {
+            using var scope = factory.Services.CreateScope();
+            var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+            SetFreeplayEnabled(db, enabled: true);
+
+            var viewer = await db.Viewers
+                .Include(v => v.LeaderSkins)
+                .Include(v => v.Sleeves)
+                .Include(v => v.Emblems)
+                .Include(v => v.Degrees)
+                .Include(v => v.MyPageBackgrounds)
+                .FirstAsync(v => v.Id == viewerId);
+
+            var ent = Build(scope);
+            var cosmetics = await ent.EffectiveCosmeticsAsync(viewer);
+
+            int masterSkinCount = db.LeaderSkins.Count();
+            Assert.That(cosmetics.AllLeaderSkins.Count, Is.EqualTo(masterSkinCount),
+                "AllLeaderSkins count unchanged when freeplay is on");
+            Assert.That(cosmetics.OwnedLeaderSkinIds.Count, Is.EqualTo(masterSkinCount),
+                "freeplay: every skin id must be in OwnedLeaderSkinIds");
+
+            // All four id-lists should equal the full catalog counts.
+            Assert.That(cosmetics.SleeveIds.Count, Is.EqualTo(db.Sleeves.Count()),
+                "freeplay: SleeveIds should equal full sleeve catalog");
+            Assert.That(cosmetics.EmblemIds.Count, Is.EqualTo(db.Emblems.Count()),
+                "freeplay: EmblemIds should equal full emblem catalog");
+            Assert.That(cosmetics.DegreeIds.Count, Is.EqualTo(db.Degrees.Count()),
+                "freeplay: DegreeIds should equal full degree catalog");
+            Assert.That(cosmetics.MyPageBackgroundIds.Count, Is.EqualTo(db.MyPageBackgrounds.Count()),
+                "freeplay: MyPageBackgroundIds should equal full my-page-background catalog");
+        }
+    }
 }