fix(pack): /pack/info reads ItemId via shadow FK, not nav property

PackController.Info's ownedItemsByItemId projection used `i.Item.Id` to
key the dict — EF translates that to the FK column today, but any future
model change that breaks the nav→column mapping would fall back to client
eval and collapse every key to 0 (the default Item constructor's Id),
silently hiding every tutorial pack via item_number=0. EF.Property<int>
reads the shadow FK directly and is robust to nav changes.

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

SVSim.EmulatedEntrypoint/Controllers/PackController.cs

@@ -63,10 +63,18 @@ public class PackController : SVSimController
         // OwnedItemEntry is [Owned] by Viewer, and EF refuses to track owned entities without
         // their owner in the result. Project to primitive pairs in the database query before
         // materialising into the dictionary — no entity tracking, single round-trip.
+        //
+        // Use EF.Property<int>(i, "ItemId") to read the shadow FK directly instead of going
+        // through the OwnedItemEntry.Item nav. The nav route works today (EF translates
+        // `i.Item.Id` to the FK column), but a future model change that renames the FK or
+        // breaks the nav→column mapping would silently fall back to client eval — where
+        // `i.Item.Id` returns 0 for every row (the default-initialised ItemEntry) and the
+        // dictionary collapses every ticket to item_number=0. Shadow-FK access bypasses
+        // that hazard entirely.
         var ownedItemsByItemId = await _db.Viewers
             .Where(v => v.Id == viewerId)
             .SelectMany(v => v.Items)
-            .Select(i => new { ItemId = (long)i.Item.Id, i.Count })
+            .Select(i => new { ItemId = (long)EF.Property<int>(i, "ItemId"), i.Count })
             .ToDictionaryAsync(x => x.ItemId, x => x.Count);
 
         return new PackInfoResponse

SVSim.UnitTests/Controllers/PackControllerTests.cs

@@ -12,6 +12,38 @@ namespace SVSim.UnitTests.Controllers;
 
 public class PackControllerTests
 {
+    [Test]
+    public async Task PackInfo_item_number_reflects_owned_ticket_count()
+    {
+        // Verifies the ownedItemsByItemId projection in PackController.Info — the dict that
+        // drives child_gacha_info.item_number. Tutorial flow filters packs by item_number > 0,
+        // so a regression on the projection (e.g. nav-eval collapsing to 0) silently hides
+        // any pack that requires a ticket.
+        using var factory = new SVSimTestFactory();
+        await factory.SeedGlobalsAsync();
+        long viewerId = await factory.SeedViewerAsync(tutorialState: 41);
+
+        // Seed item 90001 with count 7 — the legendary starter ticket the tutorial gift grants.
+        await factory.SeedOwnedItemAsync(viewerId, itemId: 90001, count: 7, itemName: "Starter Legendary Ticket");
+
+        using var client = factory.CreateAuthenticatedClient(viewerId);
+        var json = """{"viewer_id":"0","steam_id":0,"steam_session_ticket":""}""";
+        var response = await client.PostAsync("/pack/info",
+            new StringContent(json, Encoding.UTF8, "application/json"));
+
+        Assert.That(response.StatusCode, Is.EqualTo(HttpStatusCode.OK));
+        using var doc = JsonDocument.Parse(await response.Content.ReadAsStringAsync());
+
+        // Find pack 99047 (the starter legendary) and verify its child gacha reports item_number=7.
+        var pack99047 = doc.RootElement.GetProperty("pack_config_list").EnumerateArray()
+            .First(p => p.GetProperty("parent_gacha_id").GetInt32() == 99047);
+        var childWithTicket = pack99047.GetProperty("child_gacha_info").EnumerateArray()
+            .First(c => c.TryGetProperty("item_id", out var iid) && iid.GetString() == "90001");
+        Assert.That(childWithTicket.GetProperty("item_number").GetInt32(), Is.EqualTo(7),
+            "child_gacha_info.item_number must reflect the viewer's owned count of the gating " +
+            "item; client filters tutorial packs on item_number > 0.");
+    }
+
     [Test]
     public async Task TutorialPackInfo_returns_same_list_as_pack_info()
     {