refactor(arena-colosseum): dedup colosseum_info source-of-truth

/mypage/index data.colosseum_info and /arena_colosseum/{top,get_fee_info}
now both project through ColosseumLobbyInfoBuilder.Build(ColosseumSeasonConfig).
One source of truth for the home-tab gating and the lobby reads — admins
flip the season on by writing to GameConfigs (per the runbook), no second
table to keep in sync.

* New ColosseumLobbyInfoBuilder — static projection from ColosseumSeasonConfig
  to the wire ColosseumLobbyInfo. Replaces ArenaColosseumController's private
  BuildColosseumInfo and MyPageController's BuildColosseumInfo(ColosseumConfig).
* MyPageController reads ColosseumSeasonConfig via IGameConfigService; the
  IGlobalsRepository.GetCurrentColosseum() call goes away.
* MyPageIndexResponse.ColosseumInfo retyped to the new ColosseumLobbyInfo.
* ColosseumSalesPeriodInfo relocated into the ArenaColosseum namespace
  alongside the rest of the family DTOs.
* Drops: Colosseums DB table (migration DropColosseumsTable), ColosseumConfig
  entity, the captured-shape Models.Dtos.ColosseumInfo DTO, ColosseumSeed,
  MyPageGlobalsImporter.ImportColosseumAsync + seed file colosseum.json,
  IGlobalsRepository.GetCurrentColosseum + impl, the two related tests.

Net: home-screen Grand Prix tab now hidden by default because the season
ships with IsColosseumPeriod=false. Full suite: 1345/1345 (was 1347 — the
2 dropped tests covered the now-dead surface).

SVSim.Bootstrap/Data/seeds/colosseum.json

@@ -1,20 +0,0 @@
-{
-  "id": 1,
-  "colosseum_id": "165",
-  "colosseum_name": "Rivenbrandt Take Two Cup",
-  "card_pool_name": "Take Two (Dragonblade–Rivenbrandt)",
-  "deck_format": "3",
-  "start_time": "2026-05-21 06:00:00",
-  "end_time": "2026-05-25 19:59:59",
-  "now_round": "1",
-  "is_display_tips": "0",
-  "tips_id": "0",
-  "is_colosseum_period": true,
-  "is_round_period": true,
-  "is_normal_two_pick": "1",
-  "is_special_mode": "10",
-  "is_all_card_enabled": 0,
-  "sales_period_info": {
-    "sales_period_time": "2026-05-25 19:59:59"
-  }
-}

SVSim.Bootstrap/Importers/MyPageGlobalsImporter.cs

@@ -81,42 +81,6 @@ public class MyPageGlobalsImporter
         return seed.Count;
     }
 
-    public async Task<int> ImportColosseumAsync(SVSimDbContext context, string seedDir)
-    {
-        var s = SeedLoader.LoadObject<ColosseumSeed>(Path.Combine(seedDir, "colosseum.json"));
-        if (s is null)
-        {
-            Console.WriteLine("[MyPageGlobalsImporter] No colosseum seed; skipping.");
-            return 0;
-        }
-
-        var existing = await context.Colosseums.FirstOrDefaultAsync(e => e.Id == 1);
-        var entry = existing ?? new ColosseumConfig { Id = 1 };
-
-        entry.ColosseumId = s.ColosseumId;
-        entry.ColosseumName = s.ColosseumName;
-        entry.CardPoolName = s.CardPoolName;
-        entry.DeckFormat = s.DeckFormat;
-        entry.StartTime = ImporterBase.ParseWireDateTime(s.StartTime);
-        entry.EndTime = ImporterBase.ParseWireDateTime(s.EndTime);
-        entry.NowRound = s.NowRound;
-        entry.IsDisplayTips = s.IsDisplayTips;
-        entry.TipsId = s.TipsId;
-        entry.IsColosseumPeriod = s.IsColosseumPeriod;
-        entry.IsRoundPeriod = s.IsRoundPeriod;
-        entry.IsNormalTwoPick = s.IsNormalTwoPick;
-        entry.IsSpecialMode = s.IsSpecialMode;
-        entry.IsAllCardEnabled = s.IsAllCardEnabled;
-        entry.SalesPeriodInfo = s.SalesPeriodInfo.ValueKind == JsonValueKind.Undefined
-            ? "{}"
-            : JsonSerializer.Serialize(s.SalesPeriodInfo);
-
-        if (existing is null) context.Colosseums.Add(entry);
-        await context.SaveChangesAsync();
-        Console.WriteLine($"[MyPageGlobalsImporter] Colosseum: {(existing is null ? "+1" : "~1")}");
-        return 1;
-    }
-
     public async Task<int> ImportSealedAsync(SVSimDbContext context, string seedDir)
     {
         var s = SeedLoader.LoadObject<SealedSeasonSeed>(Path.Combine(seedDir, "sealed-season.json"));

SVSim.Bootstrap/Models/Seed/ColosseumSeed.cs

@@ -1,24 +0,0 @@
-using System.Text.Json;
-using System.Text.Json.Serialization;
-
-namespace SVSim.Bootstrap.Models.Seed;
-
-public sealed class ColosseumSeed
-{
-    [JsonPropertyName("id")] public int Id { get; set; } = 1;
-    [JsonPropertyName("colosseum_id")] public string ColosseumId { get; set; } = "";
-    [JsonPropertyName("colosseum_name")] public string ColosseumName { get; set; } = "";
-    [JsonPropertyName("card_pool_name")] public string CardPoolName { get; set; } = "";
-    [JsonPropertyName("deck_format")] public string DeckFormat { get; set; } = "";
-    [JsonPropertyName("start_time")] public string StartTime { get; set; } = "";
-    [JsonPropertyName("end_time")] public string EndTime { get; set; } = "";
-    [JsonPropertyName("now_round")] public string NowRound { get; set; } = "";
-    [JsonPropertyName("is_display_tips")] public string IsDisplayTips { get; set; } = "";
-    [JsonPropertyName("tips_id")] public string TipsId { get; set; } = "";
-    [JsonPropertyName("is_colosseum_period")] public bool IsColosseumPeriod { get; set; }
-    [JsonPropertyName("is_round_period")] public bool IsRoundPeriod { get; set; }
-    [JsonPropertyName("is_normal_two_pick")] public string IsNormalTwoPick { get; set; } = "";
-    [JsonPropertyName("is_special_mode")] public string IsSpecialMode { get; set; } = "";
-    [JsonPropertyName("is_all_card_enabled")] public int IsAllCardEnabled { get; set; }
-    [JsonPropertyName("sales_period_info")] public JsonElement SalesPeriodInfo { get; set; }
-}

SVSim.Bootstrap/Program.cs

@@ -114,7 +114,6 @@ public static class Program
 
             var mypage = new MyPageGlobalsImporter();
             await mypage.ImportBannersAsync(context, opts.SeedDir);
-            await mypage.ImportColosseumAsync(context, opts.SeedDir);
             await mypage.ImportSealedAsync(context, opts.SeedDir);
             await mypage.ImportMasterPointRankingPeriodAsync(context, opts.SeedDir);
             await mypage.ImportSpecialDeckFormatsAsync(context, opts.SeedDir);

SVSim.Database/Migrations/20260613172735_DropColosseumsTable.cs

@@ -0,0 +1,50 @@
+using System;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace SVSim.Database.Migrations
+{
+    /// <inheritdoc />
+    public partial class DropColosseumsTable : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropTable(
+                name: "Colosseums");
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateTable(
+                name: "Colosseums",
+                columns: table => new
+                {
+                    Id = table.Column<int>(type: "integer", nullable: false),
+                    CardPoolName = table.Column<string>(type: "text", nullable: false),
+                    ColosseumId = table.Column<string>(type: "text", nullable: false),
+                    ColosseumName = table.Column<string>(type: "text", nullable: false),
+                    DateCreated = table.Column<DateTime>(type: "timestamp with time zone", nullable: false),
+                    DateUpdated = table.Column<DateTime>(type: "timestamp with time zone", nullable: true),
+                    DeckFormat = table.Column<string>(type: "text", nullable: false),
+                    EndTime = table.Column<DateTime>(type: "timestamp with time zone", nullable: false),
+                    IsAllCardEnabled = table.Column<int>(type: "integer", nullable: false),
+                    IsColosseumPeriod = table.Column<bool>(type: "boolean", nullable: false),
+                    IsDisplayTips = table.Column<string>(type: "text", nullable: false),
+                    IsNormalTwoPick = table.Column<string>(type: "text", nullable: false),
+                    IsRoundPeriod = table.Column<bool>(type: "boolean", nullable: false),
+                    IsSpecialMode = table.Column<string>(type: "text", nullable: false),
+                    NowRound = table.Column<string>(type: "text", nullable: false),
+                    SalesPeriodInfo = table.Column<string>(type: "jsonb", nullable: false),
+                    StartTime = table.Column<DateTime>(type: "timestamp with time zone", nullable: false),
+                    TipsId = table.Column<string>(type: "text", nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_Colosseums", x => x.Id);
+                });
+        }
+    }
+}

SVSim.Database/Migrations/SVSimDbContextModelSnapshot.cs

@@ -1005,77 +1005,6 @@ namespace SVSim.Database.Migrations
                     b.ToTable("ColosseumAvatarDecks");
                 });
 
-            modelBuilder.Entity("SVSim.Database.Models.ColosseumConfig", b =>
-                {
-                    b.Property<int>("Id")
-                        .HasColumnType("integer");
-
-                    b.Property<string>("CardPoolName")
-                        .IsRequired()
-                        .HasColumnType("text");
-
-                    b.Property<string>("ColosseumId")
-                        .IsRequired()
-                        .HasColumnType("text");
-
-                    b.Property<string>("ColosseumName")
-                        .IsRequired()
-                        .HasColumnType("text");
-
-                    b.Property<DateTime>("DateCreated")
-                        .HasColumnType("timestamp with time zone");
-
-                    b.Property<DateTime?>("DateUpdated")
-                        .HasColumnType("timestamp with time zone");
-
-                    b.Property<string>("DeckFormat")
-                        .IsRequired()
-                        .HasColumnType("text");
-
-                    b.Property<DateTime>("EndTime")
-                        .HasColumnType("timestamp with time zone");
-
-                    b.Property<int>("IsAllCardEnabled")
-                        .HasColumnType("integer");
-
-                    b.Property<bool>("IsColosseumPeriod")
-                        .HasColumnType("boolean");
-
-                    b.Property<string>("IsDisplayTips")
-                        .IsRequired()
-                        .HasColumnType("text");
-
-                    b.Property<string>("IsNormalTwoPick")
-                        .IsRequired()
-                        .HasColumnType("text");
-
-                    b.Property<bool>("IsRoundPeriod")
-                        .HasColumnType("boolean");
-
-                    b.Property<string>("IsSpecialMode")
-                        .IsRequired()
-                        .HasColumnType("text");
-
-                    b.Property<string>("NowRound")
-                        .IsRequired()
-                        .HasColumnType("text");
-
-                    b.Property<string>("SalesPeriodInfo")
-                        .IsRequired()
-                        .HasColumnType("jsonb");
-
-                    b.Property<DateTime>("StartTime")
-                        .HasColumnType("timestamp with time zone");
-
-                    b.Property<string>("TipsId")
-                        .IsRequired()
-                        .HasColumnType("text");
-
-                    b.HasKey("Id");
-
-                    b.ToTable("Colosseums");
-                });
-
             modelBuilder.Entity("SVSim.Database.Models.ColosseumHofDeck", b =>
                 {
                     b.Property<long>("Id")

SVSim.Database/Models/ColosseumConfig.cs

@@ -1,42 +0,0 @@
-using System.ComponentModel.DataAnnotations.Schema;
-using SVSim.Database.Common;
-
-namespace SVSim.Database.Models;
-
-/// <summary>
-/// Singleton row (Id=1) for the current Colosseum event from /mypage/index data.colosseum_info.
-/// Time-bound — recapture per Colosseum cycle (every few weeks).
-/// </summary>
-public class ColosseumConfig : BaseEntity<int>
-{
-    public string ColosseumId { get; set; } = string.Empty;
-
-    public string ColosseumName { get; set; } = string.Empty;
-
-    public string CardPoolName { get; set; } = string.Empty;
-
-    public string DeckFormat { get; set; } = string.Empty;
-
-    public DateTime StartTime { get; set; }
-
-    public DateTime EndTime { get; set; }
-
-    public string NowRound { get; set; } = string.Empty;
-
-    public string IsDisplayTips { get; set; } = string.Empty;
-
-    public string TipsId { get; set; } = string.Empty;
-
-    public bool IsColosseumPeriod { get; set; }
-
-    public bool IsRoundPeriod { get; set; }
-
-    public string IsNormalTwoPick { get; set; } = string.Empty;
-
-    public string IsSpecialMode { get; set; } = string.Empty;
-
-    public int IsAllCardEnabled { get; set; }
-
-    [Column(TypeName = "jsonb")]
-    public string SalesPeriodInfo { get; set; } = "{}";
-}

SVSim.Database/Repositories/Globals/GlobalsRepository.cs

@@ -72,9 +72,6 @@ public class GlobalsRepository : IGlobalsRepository
             .ThenBy(e => e.Id)
             .ToListAsync();
 
-    public Task<ColosseumConfig?> GetCurrentColosseum() =>
-        _dbContext.Colosseums.AsNoTracking().FirstOrDefaultAsync(e => e.Id == 1);
-
     public Task<SealedConfig?> GetCurrentSealedSeason() =>
         _dbContext.SealedSeasons.AsNoTracking().FirstOrDefaultAsync(e => e.Id == 1);
 

SVSim.Database/Repositories/Globals/IGlobalsRepository.cs

@@ -22,7 +22,6 @@ public interface IGlobalsRepository
     Task<List<DailyLoginBonusEntry>> GetDailyLoginBonus();
     Task<List<BannerEntry>> GetBanners();
     Task<IReadOnlyList<HomeDialogEntry>> GetActiveHomeDialogsAsync(DateTime nowUtc);
-    Task<ColosseumConfig?> GetCurrentColosseum();
     Task<SealedConfig?> GetCurrentSealedSeason();
     Task<MasterPointRankingPeriodEntry?> GetCurrentMasterPointPeriod();
     Task<List<SpecialDeckFormatEntry>> GetActiveSpecialDeckFormats();

SVSim.Database/SVSimDbContext.cs

@@ -63,7 +63,6 @@ public class SVSimDbContext : DbContext
     public DbSet<DailyLoginBonusEntry> DailyLoginBonuses => Set<DailyLoginBonusEntry>();
     public DbSet<BannerEntry> Banners => Set<BannerEntry>();
     public DbSet<HomeDialogEntry> HomeDialogEntries => Set<HomeDialogEntry>();
-    public DbSet<ColosseumConfig> Colosseums => Set<ColosseumConfig>();
     public DbSet<SealedConfig> SealedSeasons => Set<SealedConfig>();
     public DbSet<MasterPointRankingPeriodEntry> MasterPointRankingPeriods => Set<MasterPointRankingPeriodEntry>();
     public DbSet<SpecialDeckFormatEntry> SpecialDeckFormats => Set<SpecialDeckFormatEntry>();

SVSim.EmulatedEntrypoint/Controllers/ArenaColosseumController.cs

@@ -688,33 +688,8 @@ public class ArenaColosseumController : SVSimController
 
     // --- helpers ---
 
-    private static ColosseumLobbyInfo BuildColosseumInfo(ColosseumSeasonConfig season)
-    {
-        if (!season.IsColosseumPeriod)
-        {
-            return new ColosseumLobbyInfo { IsColosseumPeriod = false };
-        }
-
-        return new ColosseumLobbyInfo
-        {
-            IsColosseumPeriod = true,
-            DeckFormat = (int)season.DeckFormat,
-            IsNormalTwoPick = season.IsNormalTwoPick ? "1" : "0",
-            ColosseumName = season.ColosseumName,
-            IsRoundPeriod = true,
-            IsSpecialMode = season.IsSpecialMode,
-            CardPoolName = string.IsNullOrEmpty(season.CardPoolName) ? null : season.CardPoolName,
-            NowRound = 1,
-            StartTime = FormatTime(season.EventStartTime),
-            EndTime = FormatTime(season.EventEndTime),
-            IsAllCardEnabled = season.IsAllCardEnabled ? 1 : 0,
-            SalesPeriodInfo = new SVSim.EmulatedEntrypoint.Models.Dtos.ColosseumSalesPeriodInfo
-            {
-                SalesPeriodTime = FormatTime(season.SalesPeriodEnd),
-            },
-            StrategyPickNum = season.StrategyPickNum > 0 ? season.StrategyPickNum : null,
-        };
-    }
+    private static ColosseumLobbyInfo BuildColosseumInfo(ColosseumSeasonConfig season) =>
+        ColosseumLobbyInfoBuilder.Build(season);
 
     /// <summary>Builds the <c>colosseum_status</c> block. When the viewer has no run, every
     /// property is null and global WhenWritingNull renders <c>{}</c> — the client

SVSim.EmulatedEntrypoint/Controllers/MyPageController.cs

@@ -9,6 +9,7 @@ using SVSim.Database.Services;
 using SVSim.EmulatedEntrypoint.Constants;
 using SVSim.EmulatedEntrypoint.Infrastructure;
 using SVSim.EmulatedEntrypoint.Models.Dtos;
+using SVSim.EmulatedEntrypoint.Models.Dtos.ArenaColosseum;
 using SVSim.EmulatedEntrypoint.Models.Dtos.Common;
 using SVSim.EmulatedEntrypoint.Models.Dtos.Requests;
 using SVSim.EmulatedEntrypoint.Models.Dtos.Requests.MyPage;
@@ -61,7 +62,7 @@ public class MyPageController : SVSimController
 
         // Hydrate all the globals slices in parallel-ish — they're independent reads.
         var rotation = _config.Get<RotationConfig>();
-        var colosseum = await _globalsRepository.GetCurrentColosseum();
+        var colosseumSeason = _config.Get<ColosseumSeasonConfig>();
         var sealedSeason = await _globalsRepository.GetCurrentSealedSeason();
         var masterPointPeriod = await _globalsRepository.GetCurrentMasterPointPeriod();
         var bannerEntries = await _globalsRepository.GetBanners();
@@ -93,7 +94,7 @@ public class MyPageController : SVSimController
             ArenaInfo = await BuildArenaInfosAsync(viewer.Id),
             IsArenaChallengePeriod = false,                         // TODO(mypage-stub): globals/ArenaSeason flag
             IsAvailableColosseumFreeEntry = false,                  // TODO(mypage-stub): viewer + globals free-entry quota
-            ColosseumInfo = BuildColosseumInfo(colosseum),
+            ColosseumInfo = ColosseumLobbyInfoBuilder.Build(colosseumSeason),
             SealedInfo = BuildSealedInfo(sealedSeason),
             Banner = bannerEntries.Select(BuildBannerInfo).ToList(),
             RoomTypeInSession = new RoomTypeInSession
@@ -237,37 +238,6 @@ public class MyPageController : SVSimController
         };
     }
 
-    private ColosseumInfo BuildColosseumInfo(ColosseumConfig? row)
-    {
-        if (row is null) return new ColosseumInfo();
-
-        ColosseumSalesPeriodInfo sales = new();
-        if (!string.IsNullOrEmpty(row.SalesPeriodInfo) && row.SalesPeriodInfo != "{}")
-        {
-            sales = JsonSerializer.Deserialize<ColosseumSalesPeriodInfo>(row.SalesPeriodInfo, JsonbReadOptions.Instance)
-                    ?? new ColosseumSalesPeriodInfo();
-        }
-
-        return new ColosseumInfo
-        {
-            ColosseumId = row.ColosseumId,
-            IsDisplayTips = row.IsDisplayTips,
-            TipsId = row.TipsId,
-            CardPoolName = row.CardPoolName,
-            IsColosseumPeriod = row.IsColosseumPeriod,
-            IsRoundPeriod = row.IsRoundPeriod,
-            DeckFormat = row.DeckFormat,
-            IsNormalTwoPick = row.IsNormalTwoPick,
-            IsSpecialMode = row.IsSpecialMode,
-            IsAllCardEnabled = row.IsAllCardEnabled,
-            StartTime = row.StartTime.ToString(WireDateFormat, CultureInfo.InvariantCulture),
-            ColosseumName = row.ColosseumName,
-            NowRound = row.NowRound,
-            EndTime = row.EndTime.ToString(WireDateFormat, CultureInfo.InvariantCulture),
-            SalesPeriodInfo = sales,
-        };
-    }
-
     private SealedInfo BuildSealedInfo(SealedConfig? row)
     {
         if (row is null) return new SealedInfo();

SVSim.EmulatedEntrypoint/Models/Dtos/ArenaColosseum/ColosseumInfo.cs

@@ -1,6 +1,5 @@
 using System.Text.Json.Serialization;
 using MessagePack;
-using SVSim.EmulatedEntrypoint.Models.Dtos;
 
 namespace SVSim.EmulatedEntrypoint.Models.Dtos.ArenaColosseum;
 
@@ -10,10 +9,11 @@ namespace SVSim.EmulatedEntrypoint.Models.Dtos.ArenaColosseum;
 /// <see cref="IsColosseumPeriod"/> is <c>false</c>, the client skips parsing every other
 /// field — server still emits this minimal payload so the lobby renders cleanly.
 /// <para>
-/// Distinct from <see cref="SVSim.EmulatedEntrypoint.Models.Dtos.ColosseumInfo"/> (the
-/// captured prod <c>/mypage/index</c> shape — stringly-typed and read-only). This is the
-/// per-endpoint Colosseum-family shape. <c>/event_info</c> uses yet a third shape —
-/// <see cref="ColosseumEventInfo"/>.
+/// Also drives <c>/mypage/index data.colosseum_info</c> — the home-screen tab gating and
+/// the per-endpoint lobby reads share one source of truth (the
+/// <see cref="ColosseumSeasonConfig"/> POCO) projected via
+/// <see cref="ColosseumLobbyInfoBuilder"/>. <c>/event_info</c> uses a different,
+/// event-level shape — <see cref="ColosseumEventInfo"/>.
 /// </para>
 /// </summary>
 [MessagePackObject]

SVSim.EmulatedEntrypoint/Models/Dtos/ArenaColosseum/ColosseumLobbyInfoBuilder.cs

@@ -0,0 +1,48 @@
+using System.Globalization;
+using SVSim.Database.Models.Config;
+
+namespace SVSim.EmulatedEntrypoint.Models.Dtos.ArenaColosseum;
+
+/// <summary>
+/// Single source of truth for projecting <see cref="ColosseumSeasonConfig"/> onto the wire
+/// <see cref="ColosseumLobbyInfo"/> block. Used by both <c>/arena_colosseum/{top,get_fee_info}</c>
+/// AND <c>/mypage/index data.colosseum_info</c> — the home-screen tab and the lobby reads
+/// must agree on the season state, so they go through one builder. When
+/// <c>IsColosseumPeriod = false</c> the minimal "no event" payload is emitted; the client
+/// gates every other field on that flag (<c>Wizard/ColosseumEntryInfoTask.cs:100</c>).
+/// </summary>
+public static class ColosseumLobbyInfoBuilder
+{
+    private const string WireDateFormat = "yyyy-MM-dd HH:mm:ss";
+
+    public static ColosseumLobbyInfo Build(ColosseumSeasonConfig season)
+    {
+        if (!season.IsColosseumPeriod)
+        {
+            return new ColosseumLobbyInfo { IsColosseumPeriod = false };
+        }
+
+        return new ColosseumLobbyInfo
+        {
+            IsColosseumPeriod = true,
+            DeckFormat = (int)season.DeckFormat,
+            IsNormalTwoPick = season.IsNormalTwoPick ? "1" : "0",
+            ColosseumName = season.ColosseumName,
+            IsRoundPeriod = true,
+            IsSpecialMode = season.IsSpecialMode,
+            CardPoolName = string.IsNullOrEmpty(season.CardPoolName) ? null : season.CardPoolName,
+            NowRound = 1,
+            StartTime = FormatTime(season.EventStartTime),
+            EndTime = FormatTime(season.EventEndTime),
+            IsAllCardEnabled = season.IsAllCardEnabled ? 1 : 0,
+            SalesPeriodInfo = new ColosseumSalesPeriodInfo
+            {
+                SalesPeriodTime = FormatTime(season.SalesPeriodEnd),
+            },
+            StrategyPickNum = season.StrategyPickNum > 0 ? season.StrategyPickNum : null,
+        };
+    }
+
+    private static string FormatTime(DateTime t) =>
+        t == default ? "" : t.ToString(WireDateFormat, CultureInfo.InvariantCulture);
+}

SVSim.EmulatedEntrypoint/Models/Dtos/ArenaColosseum/ColosseumSalesPeriodInfo.cs

@@ -0,0 +1,16 @@
+using System.Text.Json.Serialization;
+using MessagePack;
+
+namespace SVSim.EmulatedEntrypoint.Models.Dtos.ArenaColosseum;
+
+/// <summary>
+/// Nested under <c>colosseum_info.sales_period_info</c>. Captured prod shape — single
+/// <c>sales_period_time</c> field carrying the wall-clock end of the cup's sales window.
+/// Format <c>"yyyy-MM-dd HH:mm:ss"</c> (PHP convention, not ISO).
+/// </summary>
+[MessagePackObject]
+public sealed class ColosseumSalesPeriodInfo
+{
+    [JsonPropertyName("sales_period_time")] [Key("sales_period_time")]
+    public string SalesPeriodTime { get; set; } = string.Empty;
+}

SVSim.EmulatedEntrypoint/Models/Dtos/ColosseumInfo.cs

@@ -1,97 +0,0 @@
-using MessagePack;
-using System.Text.Json.Serialization;
-
-namespace SVSim.EmulatedEntrypoint.Models.Dtos;
-
-/// <summary>
-/// colosseum_info on /mypage/index, consumed by ColosseumEntryInfoTask.SetColosseumInfo
-/// (Wizard/ColosseumEntryInfoTask.cs:99). The outer object is read unconditionally, and
-/// is_colosseum_period gates everything else. When a cup IS active, the client reads
-/// many more sub-fields inside the gate (deck_format, now_round, start_time, end_time,
-/// sales_period_info, etc.) — we now mirror the full prod shape so the gate-true branch
-/// works once we have colosseum data seeded.
-///
-/// Prod-captured shape (15 fields):
-/// <code>
-/// {"colosseum_id":"165","is_display_tips":"0","tips_id":"0",
-///  "card_pool_name":"Take Two (Dragonblade–Rivenbrandt)",
-///  "is_colosseum_period":true,"is_round_period":true,"deck_format":"3",
-///  "is_normal_two_pick":"1","is_special_mode":"10","is_all_card_enabled":0,
-///  "start_time":"2026-05-21 06:00:00","colosseum_name":"Rivenbrandt Take Two Cup",
-///  "now_round":"1","end_time":"2026-05-25 19:59:59",
-///  "sales_period_info":{"sales_period_time":"2026-05-25 19:59:59"}}
-/// </code>
-/// </summary>
-[MessagePackObject]
-public class ColosseumInfo
-{
-    [JsonPropertyName("colosseum_id")]
-    [Key("colosseum_id")]
-    public string ColosseumId { get; set; } = string.Empty;
-
-    /// <summary>Wire is "0"/"1" string. Client compares with == "1" (GetValueOrDefault-guarded).</summary>
-    [JsonPropertyName("is_display_tips")]
-    [Key("is_display_tips")]
-    public string IsDisplayTips { get; set; } = "0";
-
-    [JsonPropertyName("tips_id")]
-    [Key("tips_id")]
-    public string TipsId { get; set; } = "0";
-
-    [JsonPropertyName("card_pool_name")]
-    [Key("card_pool_name")]
-    public string CardPoolName { get; set; } = string.Empty;
-
-    [JsonPropertyName("is_colosseum_period")]
-    [Key("is_colosseum_period")]
-    public bool IsColosseumPeriod { get; set; }
-
-    [JsonPropertyName("is_round_period")]
-    [Key("is_round_period")]
-    public bool IsRoundPeriod { get; set; }
-
-    /// <summary>
-    /// Wire is a stringified int in prod (e.g. "3"). DB stores as string. Client calls
-    /// <c>jsonData["deck_format"].ToInt()</c> inside the IsColosseumPeriod gate.
-    /// </summary>
-    [JsonPropertyName("deck_format")]
-    [Key("deck_format")]
-    public string DeckFormat { get; set; } = "0";
-
-    /// <summary>Wire is "1"/"0" string. Client compares with == "1".</summary>
-    [JsonPropertyName("is_normal_two_pick")]
-    [Key("is_normal_two_pick")]
-    public string IsNormalTwoPick { get; set; } = "0";
-
-    /// <summary>Used as ColorCodeId (stringified int).</summary>
-    [JsonPropertyName("is_special_mode")]
-    [Key("is_special_mode")]
-    public string IsSpecialMode { get; set; } = "0";
-
-    [JsonPropertyName("is_all_card_enabled")]
-    [Key("is_all_card_enabled")]
-    public int IsAllCardEnabled { get; set; }
-
-    /// <summary>"yyyy-MM-dd HH:mm:ss" wire format.</summary>
-    [JsonPropertyName("start_time")]
-    [Key("start_time")]
-    public string StartTime { get; set; } = string.Empty;
-
-    [JsonPropertyName("colosseum_name")]
-    [Key("colosseum_name")]
-    public string ColosseumName { get; set; } = string.Empty;
-
-    /// <summary>Round number as string (e.g. "1"). Client casts to int.</summary>
-    [JsonPropertyName("now_round")]
-    [Key("now_round")]
-    public string NowRound { get; set; } = "0";
-
-    /// <summary>"yyyy-MM-dd HH:mm:ss" wire format.</summary>
-    [JsonPropertyName("end_time")]
-    [Key("end_time")]
-    public string EndTime { get; set; } = string.Empty;
-
-    [JsonPropertyName("sales_period_info")]
-    [Key("sales_period_info")]
-    public ColosseumSalesPeriodInfo SalesPeriodInfo { get; set; } = new();
-}

SVSim.EmulatedEntrypoint/Models/Dtos/ColosseumSalesPeriodInfo.cs

@@ -1,18 +0,0 @@
-using MessagePack;
-using System.Text.Json.Serialization;
-
-namespace SVSim.EmulatedEntrypoint.Models.Dtos;
-
-/// <summary>
-/// Nested under /mypage/index data.colosseum_info.sales_period_info. Carries the wall-clock end of
-/// the current cup's sales window. Captured from prod:
-/// <c>"sales_period_info": { "sales_period_time": "2026-05-25 19:59:59" }</c>.
-/// </summary>
-[MessagePackObject]
-public class ColosseumSalesPeriodInfo
-{
-    /// <summary>Wire format is "yyyy-MM-dd HH:mm:ss" (prod's PHP convention, not ISO).</summary>
-    [JsonPropertyName("sales_period_time")]
-    [Key("sales_period_time")]
-    public string SalesPeriodTime { get; set; } = string.Empty;
-}

SVSim.EmulatedEntrypoint/Models/Dtos/Responses/MyPageIndexResponse.cs

@@ -1,5 +1,6 @@
 using MessagePack;
 using SVSim.Database.Enums;
+using SVSim.EmulatedEntrypoint.Models.Dtos.ArenaColosseum;
 using System.Text.Json.Serialization;
 
 namespace SVSim.EmulatedEntrypoint.Models.Dtos.Responses;
@@ -134,11 +135,13 @@ public class MyPageIndexResponse
     /// <summary>
     /// Required — ColosseumEntryInfoTask.SetColosseumInfo indexes this key
     /// directly (Wizard/ColosseumEntryInfoTask.cs:102) and reads
-    /// is_colosseum_period without a guard.
+    /// is_colosseum_period without a guard. Built by
+    /// <see cref="ColosseumLobbyInfoBuilder"/> from <c>ColosseumSeasonConfig</c> —
+    /// shared with <c>/arena_colosseum/{top,get_fee_info}</c>.
     /// </summary>
     [JsonPropertyName("colosseum_info")]
     [Key("colosseum_info")]
-    public ColosseumInfo ColosseumInfo { get; set; } = new();
+    public ColosseumLobbyInfo ColosseumInfo { get; set; } = new();
 
     // ── Convention / offline event ─────────────────────────────────────────
 

SVSim.UnitTests/Importers/MyPageGlobalsImporterTests.cs

@@ -25,22 +25,6 @@ public class MyPageGlobalsImporterTests
         Assert.That(count, Is.GreaterThan(0), "seed must contain banners");
     }
 
-    [Test]
-    public async Task Imports_colosseum_singleton()
-    {
-        using var factory = new SVSimTestFactory();
-        using var scope = factory.Services.CreateScope();
-        var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
-
-        var importer = new MyPageGlobalsImporter();
-        await importer.ImportColosseumAsync(db, SeedDir);
-
-        var row = await db.Colosseums.FirstOrDefaultAsync(e => e.Id == 1);
-        Assert.That(row, Is.Not.Null);
-        Assert.That(row!.Id, Is.EqualTo(1));
-        Assert.That(row.ColosseumId, Is.Not.Empty);
-    }
-
     [Test]
     public async Task Imports_sealed_singleton()
     {
@@ -145,14 +129,10 @@ public class MyPageGlobalsImporterTests
         var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
 
         var importer = new MyPageGlobalsImporter();
-        await importer.ImportColosseumAsync(db, SeedDir);
         await importer.ImportSealedAsync(db, SeedDir);
 
-        await importer.ImportColosseumAsync(db, SeedDir);
         await importer.ImportSealedAsync(db, SeedDir);
 
-        Assert.That(await db.Colosseums.CountAsync(), Is.EqualTo(1),
-            "Colosseum singleton must remain a single row on re-run");
         Assert.That(await db.SealedSeasons.CountAsync(), Is.EqualTo(1),
             "SealedSeason singleton must remain a single row on re-run");
     }

SVSim.UnitTests/Infrastructure/SVSimTestFactory.cs

@@ -286,7 +286,6 @@ internal class SVSimTestFactory : WebApplicationFactory<Program>
 
         var mypage = new MyPageGlobalsImporter();
         await mypage.ImportBannersAsync(ctx, seedDir);
-        await mypage.ImportColosseumAsync(ctx, seedDir);
         await mypage.ImportSealedAsync(ctx, seedDir);
         await mypage.ImportMasterPointRankingPeriodAsync(ctx, seedDir);
         await mypage.ImportSpecialDeckFormatsAsync(ctx, seedDir);

SVSim.UnitTests/Repositories/GlobalsRepositoryTests.cs

@@ -151,17 +151,6 @@ public class GlobalsRepositoryTests
         Assert.That(banners[0].Click, Is.EqualTo("account_transition_with_two"));
     }
 
-    [Test]
-    public async Task GetCurrentColosseum_returns_singleton_with_name()
-    {
-        var (factory, repo) = await SetupAsync();
-        using var _ = factory;
-        var col = await repo.GetCurrentColosseum();
-        Assert.That(col, Is.Not.Null);
-        Assert.That(col!.ColosseumName, Is.EqualTo("Rivenbrandt Take Two Cup"));
-        Assert.That(col.ColosseumId, Is.EqualTo("165"));
-    }
-
     [Test]
     public async Task GetCurrentSealedSeason_returns_singleton_with_pack_info()
     {