fix(tk2): per-viewer is_join in arena_info + stub /arena/get_challenge_info

Bug 1 ("pay to enter again after restart"):
arena_info[0].is_join shipped from the static ArenaSeasonConfig seed,
so /load/index and /mypage/index always emitted false regardless of
viewer state. The client uses is_join to choose between the "Pay to
enter" and "Resume run" dialogs (Wizard/ChallengeEntry.cs:165 + the
ArenaEntryBase._isJoinFunc pivot). Without a per-viewer override every
cold start after a partial run looked like "no run" and the player got
charged again.

LoadController + MyPageController now compute is_join from
ViewerArenaTwoPickRuns presence. MyPageController grew an
IArenaTwoPickRunRepository dep (LoadController already had _db).

Bug 2: /arena/get_challenge_info 404. Stubbed via a new
ArenaController + DTO pair. Returns the season seed's begin/end_time
+ name where available; placeholder zeros for win history. All 6 keys
required by ChallangeHistoryInfoTask.Parse are present (unconditional
JsonData lookups).

Routing smoke added for /arena/get_challenge_info.

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

SVSim.EmulatedEntrypoint/Controllers/ArenaController.cs

@@ -0,0 +1,59 @@
+using Microsoft.AspNetCore.Mvc;
+using SVSim.Database.Repositories.Globals;
+using SVSim.EmulatedEntrypoint.Models.Dtos.Requests.Arena;
+using SVSim.EmulatedEntrypoint.Models.Dtos.Responses.Arena;
+
+namespace SVSim.EmulatedEntrypoint.Controllers;
+
+/// <summary>
+/// Generic /arena/* family — primarily challenge-history info read by the TK2 entry screen's
+/// detail button. TODO: lifetime TK2 stats tracking; today we emit a stub.
+/// </summary>
+[Route("arena")]
+public class ArenaController : SVSimController
+{
+    private readonly IGlobalsRepository _globalsRepository;
+
+    public ArenaController(IGlobalsRepository globalsRepository)
+    {
+        _globalsRepository = globalsRepository;
+    }
+
+    [HttpPost("get_challenge_info")]
+    public async Task<IActionResult> GetChallengeInfo([FromBody] GetChallengeInfoRequest req)
+    {
+        if (!TryGetViewerId(out _)) return Unauthorized();
+
+        var season = await _globalsRepository.GetCurrentArenaSeason();
+        // Best-effort: pull begin/end_time + name from the season seed when present; otherwise
+        // emit deterministic stub values. All 6 ChallangeHistoryInfoTask.Parse fields must be
+        // present — the parser accesses them unconditionally.
+        var beginTime = "2026-05-01 02:00:00";
+        var endTime = "2026-06-01 01:59:59";
+        var name = "Take Two";
+        if (season is not null && !string.IsNullOrEmpty(season.FormatInfo) && season.FormatInfo != "{}")
+        {
+            try
+            {
+                using var doc = System.Text.Json.JsonDocument.Parse(season.FormatInfo);
+                if (doc.RootElement.TryGetProperty("start_time", out var st)) beginTime = st.GetString() ?? beginTime;
+                if (doc.RootElement.TryGetProperty("end_time", out var et))   endTime = et.GetString() ?? endTime;
+                if (doc.RootElement.TryGetProperty("card_pool_name", out var cp)) name = cp.GetString() ?? name;
+            }
+            catch { /* fall back to defaults */ }
+        }
+
+        return Ok(new GetChallengeInfoResponseDto
+        {
+            ChallengeName = name,
+            BeginTime = beginTime,
+            EndTime = endTime,
+            TwoPickAllWinCount = 0,
+            RewardStepInfo = new RewardStepInfoDto
+            {
+                MaxRewardStep = 0,
+                RewardStepList = new List<int>(),
+            },
+        });
+    }
+}

SVSim.EmulatedEntrypoint/Controllers/LoadController.cs

@@ -1,5 +1,6 @@
 using System.Text.Json;
 using Microsoft.AspNetCore.Mvc;
+using Microsoft.EntityFrameworkCore;
 using SVSim.Database;
 using SVSim.Database.Enums;
 using SVSim.Database.Models;
@@ -244,7 +245,7 @@ public class LoadController : SVSimController
                 UseChallengePickTwoPremiumCard = challenge.UseTwoPickPremiumCard ? 1 : 0,
                 ChallengePickTwoCardSleeve = (int)challenge.TwoPickSleeveId,
             },
-            ArenaInfos = await BuildArenaInfosAsync(),
+            ArenaInfos = await BuildArenaInfosAsync(viewer.Id),
             RotationSets = rotationSets,
             UserConfig = new UserConfig(),
             OpenBattlefieldIds = (await _globalsRepository.GetBattlefields(true))
@@ -263,7 +264,7 @@ public class LoadController : SVSimController
     /// field is omitted on the wire, which the client's <c>Keys.Contains("arena_info")</c> guard
     /// (LoadDetail.cs:261) handles cleanly.
     /// </summary>
-    private async Task<List<ArenaInfo>?> BuildArenaInfosAsync()
+    private async Task<List<ArenaInfo>?> BuildArenaInfosAsync(long viewerId)
     {
         var season = await _globalsRepository.GetCurrentArenaSeason();
         if (season is null) return null;
@@ -274,6 +275,15 @@ public class LoadController : SVSimController
             format = JsonSerializer.Deserialize<ArenaFormatInfo>(season.FormatInfo, JsonbReadOptions.Instance);
         }
 
+        // is_join must reflect the viewer's actual TK2 state — true if they have an
+        // active ViewerArenaTwoPickRun row. The client uses this to decide between the
+        // "Pay to enter" and "Resume run" dialogs (Wizard/ChallengeEntry.cs:165 + ArenaEntryBase).
+        // Without a per-viewer override here, every cold start after a partial run shows
+        // "Pay to enter" — losing the in-progress draft from the player's perspective.
+        bool hasActiveRun = await _db.ViewerArenaTwoPickRuns
+            .AsNoTracking()
+            .AnyAsync(r => r.ViewerId == viewerId);
+
         return new List<ArenaInfo>
         {
             new ArenaInfo
@@ -283,7 +293,7 @@ public class LoadController : SVSimController
                 Cost = season.Cost,
                 RupeeCost = season.RupyCost,
                 TicketCost = season.TicketCost,
-                IsJoin = season.IsJoin,
+                IsJoin = hasActiveRun,
                 FormatInfo = format,
             }
         };

SVSim.EmulatedEntrypoint/Controllers/MyPageController.cs

@@ -23,12 +23,15 @@ public class MyPageController : SVSimController
     private readonly IViewerRepository _viewerRepository;
     private readonly IGlobalsRepository _globalsRepository;
     private readonly IGameConfigService _config;
+    private readonly IArenaTwoPickRunRepository _arenaTwoPickRuns;
 
-    public MyPageController(IViewerRepository viewerRepository, IGlobalsRepository globalsRepository, IGameConfigService config)
+    public MyPageController(IViewerRepository viewerRepository, IGlobalsRepository globalsRepository,
+        IGameConfigService config, IArenaTwoPickRunRepository arenaTwoPickRuns)
     {
         _viewerRepository = viewerRepository;
         _globalsRepository = globalsRepository;
         _config = config;
+        _arenaTwoPickRuns = arenaTwoPickRuns;
     }
 
     [HttpPost("index")]
@@ -69,7 +72,7 @@ public class MyPageController : SVSimController
             LastAnnounceId = 0,                                     // TODO(mypage-stub): globals announcement metadata
             LastAnnounceUpdateTime = string.Empty,                  // TODO(mypage-stub): globals announcement metadata
             FeatureMaintenanceList = new(),                         // TODO(mypage-stub): FeatureMaintenanceEntry rows
-            ArenaInfo = await BuildArenaInfosAsync(),
+            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),
@@ -155,9 +158,16 @@ public class MyPageController : SVSimController
     /// _twoPickData.ChallengeData which is only built when arena_info[0].format_info is present.
     /// So we always populate format_info from the same ArenaSeason.FormatInfo jsonb /load/index uses.
     /// </summary>
-    private async Task<List<ArenaInfo>> BuildArenaInfosAsync()
+    private async Task<List<ArenaInfo>> BuildArenaInfosAsync(long viewerId)
     {
         var season = await _globalsRepository.GetCurrentArenaSeason();
+
+        // is_join MUST reflect the viewer's actual TK2 state — true iff they have an
+        // active ViewerArenaTwoPickRun row. The client uses this to choose between the
+        // "Pay to enter" and "Resume run" dialogs (Wizard/ChallengeEntry.cs:165 + ArenaEntryBase).
+        // See LoadController.BuildArenaInfosAsync for the matching /load/index path.
+        bool hasActiveRun = (await _arenaTwoPickRuns.GetByViewerIdAsync(viewerId)) is not null;
+
         if (season is null)
         {
             return new List<ArenaInfo>
@@ -169,7 +179,7 @@ public class MyPageController : SVSimController
                     Cost = 0,
                     RupeeCost = 0,
                     TicketCost = 0,
-                    IsJoin = false,
+                    IsJoin = hasActiveRun,
                 },
             };
         }
@@ -189,7 +199,7 @@ public class MyPageController : SVSimController
                 Cost = season.Cost,
                 RupeeCost = season.RupyCost,
                 TicketCost = season.TicketCost,
-                IsJoin = season.IsJoin,
+                IsJoin = hasActiveRun,
                 FormatInfo = format,
             }
         };

SVSim.EmulatedEntrypoint/Models/Dtos/Requests/Arena/GetChallengeInfoRequest.cs

@@ -0,0 +1,7 @@
+using MessagePack;
+using SVSim.EmulatedEntrypoint.Models.Dtos.Requests;
+
+namespace SVSim.EmulatedEntrypoint.Models.Dtos.Requests.Arena;
+
+[MessagePackObject]
+public class GetChallengeInfoRequest : BaseRequest { }

SVSim.EmulatedEntrypoint/Models/Dtos/Responses/Arena/GetChallengeInfoResponseDto.cs

@@ -0,0 +1,40 @@
+using System.Text.Json.Serialization;
+using MessagePack;
+
+namespace SVSim.EmulatedEntrypoint.Models.Dtos.Responses.Arena;
+
+/// <summary>
+/// Wire shape for /arena/get_challenge_info. Parsed by Wizard/ChallangeHistoryInfoTask.cs:25.
+/// All 6 fields below are accessed unconditionally — KeyNotFoundException if any is omitted.
+/// Stub values for now; TODO: source from a per-season "challenge history" snapshot when we
+/// track viewer's lifetime TK2 stats.
+/// </summary>
+[MessagePackObject]
+public class GetChallengeInfoResponseDto
+{
+    [JsonPropertyName("challenge_name")] [Key("challenge_name")]
+    public string ChallengeName { get; set; } = "";
+
+    /// <summary>Client parses via DateTime.Parse — "yyyy-MM-dd HH:mm:ss" works.</summary>
+    [JsonPropertyName("begin_time")] [Key("begin_time")]
+    public string BeginTime { get; set; } = "";
+
+    [JsonPropertyName("end_time")] [Key("end_time")]
+    public string EndTime { get; set; } = "";
+
+    [JsonPropertyName("two_pick_all_win_count")] [Key("two_pick_all_win_count")]
+    public int TwoPickAllWinCount { get; set; }
+
+    [JsonPropertyName("reward_step_info")] [Key("reward_step_info")]
+    public RewardStepInfoDto RewardStepInfo { get; set; } = new();
+}
+
+[MessagePackObject]
+public class RewardStepInfoDto
+{
+    [JsonPropertyName("max_reward_step")] [Key("max_reward_step")]
+    public int MaxRewardStep { get; set; }
+
+    [JsonPropertyName("reward_step_list")] [Key("reward_step_list")]
+    public List<int> RewardStepList { get; set; } = new();
+}

SVSim.UnitTests/RoutingSmokeTests.cs

@@ -109,6 +109,7 @@ public class RoutingSmokeTests
     [TestCase("/arena_two_pick_battle/do_matching")]
     [TestCase("/arena_two_pick_battle/finish")]
     [TestCase("/arena_colosseum/get_fee_info")]
+    [TestCase("/arena/get_challenge_info")]
     public async Task Authenticated_route_resolves(string path)
     {
         using var factory = new TestFactory();