feat(svc): IArenaTwoPickService + response DTOs + GetTopAsync

6 response DTOs, IArenaTwoPickService interface + ArenaTwoPickException,
ArenaTwoPickService skeleton with GetTopAsync implemented and stubs for
Tasks 13-15. 3 NUnit tests for GetTopAsync all pass. DI: AddScoped.

SVSim.EmulatedEntrypoint/Models/Dtos/Responses/ArenaTwoPick/BattleFinishResultDto.cs

@@ -0,0 +1,17 @@
+namespace SVSim.EmulatedEntrypoint.Models.Dtos.Responses.ArenaTwoPick;
+
+/// <summary>
+/// What the battle controller needs from the service to build the standard battle-finish
+/// envelope (class XP delta + post-state, spot points before/add/after, battle_result echo).
+/// Achieved-info is built by the controller from IMissionAssembler.
+/// </summary>
+public class BattleFinishResultDto
+{
+    public int BattleResult { get; set; }
+    public int GetClassExperience { get; set; }
+    public int ClassExperience { get; set; }
+    public int ClassLevel { get; set; }
+    public int BeforeSpotPoint { get; set; }
+    public int AddSpotPoint { get; set; }
+    public int AfterSpotPoint { get; set; }
+}

SVSim.EmulatedEntrypoint/Models/Dtos/Responses/ArenaTwoPick/CardChooseResponseDto.cs

@@ -0,0 +1,15 @@
+using System.Text.Json.Serialization;
+using MessagePack;
+using SVSim.EmulatedEntrypoint.Models.Dtos.Common.ArenaTwoPick;
+
+namespace SVSim.EmulatedEntrypoint.Models.Dtos.Responses.ArenaTwoPick;
+
+[MessagePackObject]
+public class CardChooseResponseDto
+{
+    [JsonPropertyName("deck_info")] [Key("deck_info")]
+    public DeckInfoDto DeckInfo { get; set; } = new();
+
+    [JsonPropertyName("candidate_card_list")] [Key("candidate_card_list")]
+    public List<CandidatePairDto>? CandidateCardList { get; set; }
+}

SVSim.EmulatedEntrypoint/Models/Dtos/Responses/ArenaTwoPick/ClassChooseResponseDto.cs

@@ -0,0 +1,18 @@
+using System.Text.Json.Serialization;
+using MessagePack;
+using SVSim.EmulatedEntrypoint.Models.Dtos.Common.ArenaTwoPick;
+
+namespace SVSim.EmulatedEntrypoint.Models.Dtos.Responses.ArenaTwoPick;
+
+[MessagePackObject]
+public class ClassChooseResponseDto
+{
+    [JsonPropertyName("class_info")] [Key("class_info")]
+    public ClassInfoDto ClassInfo { get; set; } = new();
+
+    [JsonPropertyName("deck_info")] [Key("deck_info")]
+    public DeckInfoDto DeckInfo { get; set; } = new();
+
+    [JsonPropertyName("candidate_card_list")] [Key("candidate_card_list")]
+    public List<CandidatePairDto> CandidateCardList { get; set; } = new();
+}

SVSim.EmulatedEntrypoint/Models/Dtos/Responses/ArenaTwoPick/EntryResponseDto.cs

@@ -0,0 +1,21 @@
+using System.Text.Json.Serialization;
+using MessagePack;
+using SVSim.EmulatedEntrypoint.Models.Dtos.Common.ArenaTwoPick;
+
+namespace SVSim.EmulatedEntrypoint.Models.Dtos.Responses.ArenaTwoPick;
+
+[MessagePackObject]
+public class EntryResponseDto
+{
+    [JsonPropertyName("entry_info")] [Key("entry_info")]
+    public EntryInfoDto EntryInfo { get; set; } = new();
+
+    [JsonPropertyName("reward_list")] [Key("reward_list")]
+    public List<RewardEntryDto> RewardList { get; set; } = new();
+
+    [JsonPropertyName("candidate_class_ids")] [Key("candidate_class_ids")]
+    public List<int> CandidateClassIds { get; set; } = new();
+
+    [JsonPropertyName("battle_results")] [Key("battle_results")]
+    public BattleResultsDto BattleResults { get; set; } = new();
+}

SVSim.EmulatedEntrypoint/Models/Dtos/Responses/ArenaTwoPick/FinishResponseDto.cs

@@ -0,0 +1,17 @@
+using System.Text.Json.Serialization;
+using MessagePack;
+using SVSim.EmulatedEntrypoint.Models.Dtos.Common.ArenaTwoPick;
+
+namespace SVSim.EmulatedEntrypoint.Models.Dtos.Responses.ArenaTwoPick;
+
+[MessagePackObject]
+public class FinishResponseDto
+{
+    /// <summary>Per-grant deltas — drives "+N received" popup.</summary>
+    [JsonPropertyName("rewards")] [Key("rewards")]
+    public List<RewardEntryDto> Rewards { get; set; } = new();
+
+    /// <summary>Post-state totals — drives PlayerStaticData.UpdateHaveUserGoodsNumByJsonData.</summary>
+    [JsonPropertyName("reward_list")] [Key("reward_list")]
+    public List<RewardEntryDto> RewardList { get; set; } = new();
+}

SVSim.EmulatedEntrypoint/Models/Dtos/Responses/ArenaTwoPick/TopResponseDto.cs

@@ -0,0 +1,25 @@
+using System.Text.Json.Serialization;
+using MessagePack;
+using SVSim.EmulatedEntrypoint.Models.Dtos.Common;
+using SVSim.EmulatedEntrypoint.Models.Dtos.Common.ArenaTwoPick;
+
+namespace SVSim.EmulatedEntrypoint.Models.Dtos.Responses.ArenaTwoPick;
+
+[MessagePackObject]
+public class TopResponseDto
+{
+    [JsonPropertyName("entry_info")] [JsonIgnore(Condition = JsonIgnoreCondition.Never)] [Key("entry_info")]
+    public EntryInfoDto? EntryInfo { get; set; }
+
+    [JsonPropertyName("battle_results")] [Key("battle_results")]
+    public BattleResultsDto? BattleResults { get; set; }
+
+    [JsonPropertyName("class_info")] [Key("class_info")]
+    public ClassInfoDto? ClassInfo { get; set; }
+
+    [JsonPropertyName("deck_info")] [Key("deck_info")]
+    public DeckInfoDto? DeckInfo { get; set; }
+
+    [JsonPropertyName("leader_skin_id")] [JsonConverter(typeof(StringifiedLongConverter))] [Key("leader_skin_id")]
+    public long? LeaderSkinId { get; set; }
+}

SVSim.EmulatedEntrypoint/Program.cs

@@ -105,6 +105,7 @@ public class Program
         builder.Services.AddScoped<IViewerStoryProgressRepository, ViewerStoryProgressRepository>();
         builder.Services.AddScoped<IArenaTwoPickRunRepository, ArenaTwoPickRunRepository>();
         builder.Services.AddScoped<IArenaTwoPickCardPoolService, ArenaTwoPickCardPoolService>();
+        builder.Services.AddScoped<IArenaTwoPickService, ArenaTwoPickService>();
         builder.Services.AddScoped<IStoryService, StoryService>();
         builder.Services.AddScoped<IDeckListBuilder, DeckListBuilder>();
         builder.Services.AddSingleton<IRandom, SystemRandom>();

SVSim.EmulatedEntrypoint/Services/ArenaTwoPickService.cs

@@ -0,0 +1,113 @@
+using System.Text.Json;
+using SVSim.Database;
+using SVSim.Database.Models;
+using SVSim.Database.Repositories.Globals;
+using SVSim.Database.Repositories.Viewer;
+using SVSim.Database.Services;
+using SVSim.EmulatedEntrypoint.Models.Dtos.Common.ArenaTwoPick;
+using SVSim.EmulatedEntrypoint.Models.Dtos.Responses.ArenaTwoPick;
+
+namespace SVSim.EmulatedEntrypoint.Services;
+
+public class ArenaTwoPickService : IArenaTwoPickService
+{
+    private readonly IArenaTwoPickRunRepository _runs;
+    private readonly IArenaTwoPickRewardRepository _rewards;
+    private readonly IArenaTwoPickCardPoolService _pool;
+    private readonly IGameConfigService _config;
+    private readonly IViewerRepository _viewers;
+    private readonly RewardGrantService _grants;
+    private readonly IViewerEntitlements _entitlements;
+    private readonly IRandom _rng;
+    private readonly SVSimDbContext _db;
+
+    public ArenaTwoPickService(
+        IArenaTwoPickRunRepository runs,
+        IArenaTwoPickRewardRepository rewards,
+        IArenaTwoPickCardPoolService pool,
+        IGameConfigService config,
+        IViewerRepository viewers,
+        RewardGrantService grants,
+        IViewerEntitlements entitlements,
+        IRandom rng,
+        SVSimDbContext db)
+    {
+        _runs = runs; _rewards = rewards; _pool = pool; _config = config;
+        _viewers = viewers; _grants = grants; _entitlements = entitlements; _rng = rng; _db = db;
+    }
+
+    public async Task<TopResponseDto> GetTopAsync(long viewerId)
+    {
+        var run = await _runs.GetByViewerIdAsync(viewerId);
+        if (run is null) return new TopResponseDto { EntryInfo = null };
+
+        var dto = new TopResponseDto
+        {
+            EntryInfo = ProjectEntryInfo(run, viewerId),
+            BattleResults = ProjectBattleResults(run),
+        };
+        if (run.ClassId != 0)
+        {
+            dto.ClassInfo = ProjectClassInfo(run);
+            dto.DeckInfo = ProjectDeckInfo(run);
+            if (run.WinCount > 0 || run.LossCount > 0)
+                dto.LeaderSkinId = run.LeaderSkinId;
+        }
+        return dto;
+    }
+
+    public Task<EntryResponseDto> EntryAsync(long viewerId, int consumeItemType) => throw new NotImplementedException();
+    public Task<ClassChooseResponseDto> ChooseClassAsync(long viewerId, int classId) => throw new NotImplementedException();
+    public Task<CardChooseResponseDto> ChooseCardAsync(long viewerId, long selectedId) => throw new NotImplementedException();
+    public Task<FinishResponseDto> RetireAsync(long viewerId) => throw new NotImplementedException();
+    public Task<FinishResponseDto> FinishAsync(long viewerId) => throw new NotImplementedException();
+    public Task<BattleFinishResultDto> RecordBattleResultAsync(long viewerId, bool isWin) => throw new NotImplementedException();
+
+    // --- projection helpers (kept internal so test subclasses could exercise if needed) ---
+
+    internal static EntryInfoDto ProjectEntryInfo(ViewerArenaTwoPickRun run, long viewerId) => new()
+    {
+        Id = run.EntryId,
+        ViewerId = viewerId,
+        RewardScheduleId = run.RewardScheduleId,
+        ChallengeId = run.ChallengeId,
+        MaxBattleCount = run.MaxBattleCount,
+        LeaderSkinId = run.LeaderSkinId,
+        IsRetire = run.IsRetire ? 1 : 0,
+    };
+
+    internal static BattleResultsDto ProjectBattleResults(ViewerArenaTwoPickRun run)
+    {
+        var bools = JsonSerializer.Deserialize<List<bool>>(run.ResultListJson) ?? new();
+        return new()
+        {
+            ResultList = bools.Select(b => b ? 1 : 0).ToList(),
+            WinCount = run.WinCount,
+        };
+    }
+
+    internal static ClassInfoDto ProjectClassInfo(ViewerArenaTwoPickRun run)
+    {
+        var ids = JsonSerializer.Deserialize<List<int>>(run.CandidateClassIdsJson) ?? new();
+        return new()
+        {
+            ClassId1 = ids.ElementAtOrDefault(0),
+            ClassId2 = ids.ElementAtOrDefault(1),
+            ClassId3 = ids.ElementAtOrDefault(2),
+            SelectedClassId = run.ClassId,
+        };
+    }
+
+    internal static DeckInfoDto ProjectDeckInfo(ViewerArenaTwoPickRun run)
+    {
+        var cards = JsonSerializer.Deserialize<List<long>>(run.SelectedCardIdsJson) ?? new();
+        return new()
+        {
+            TwoPickEntryId = run.EntryId,
+            ClassId = run.ClassId,
+            IsSelectCompleted = run.IsSelectCompleted,
+            SelectedCardIds = cards,
+            SelectTurn = run.SelectTurn == 0 ? 1 : run.SelectTurn,
+        };
+    }
+}

SVSim.EmulatedEntrypoint/Services/IArenaTwoPickService.cs

@@ -0,0 +1,20 @@
+using SVSim.EmulatedEntrypoint.Models.Dtos.Responses.ArenaTwoPick;
+
+namespace SVSim.EmulatedEntrypoint.Services;
+
+public interface IArenaTwoPickService
+{
+    Task<TopResponseDto> GetTopAsync(long viewerId);
+    Task<EntryResponseDto> EntryAsync(long viewerId, int consumeItemType);
+    Task<ClassChooseResponseDto> ChooseClassAsync(long viewerId, int classId);
+    Task<CardChooseResponseDto> ChooseCardAsync(long viewerId, long selectedId);
+    Task<FinishResponseDto> RetireAsync(long viewerId);
+    Task<FinishResponseDto> FinishAsync(long viewerId);
+    Task<BattleFinishResultDto> RecordBattleResultAsync(long viewerId, bool isWin);
+}
+
+public class ArenaTwoPickException : Exception
+{
+    public string ErrorCode { get; }
+    public ArenaTwoPickException(string errorCode) : base(errorCode) { ErrorCode = errorCode; }
+}

SVSim.UnitTests/Services/ArenaTwoPickServiceTopTests.cs

@@ -0,0 +1,87 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.DependencyInjection;
+using NUnit.Framework;
+using SVSim.Database;
+using SVSim.Database.Models;
+using SVSim.Database.Repositories.Viewer;
+using SVSim.EmulatedEntrypoint.Services;
+using SVSim.UnitTests.Infrastructure;
+
+namespace SVSim.UnitTests.Services;
+
+public class ArenaTwoPickServiceTopTests
+{
+    private static async Task<(SVSimDbContext, IArenaTwoPickRunRepository)> SetupAsync()
+    {
+        var factory = new SVSimTestFactory();
+        var scope = factory.Services.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+        await db.Database.EnsureCreatedAsync();
+        return (db, new ArenaTwoPickRunRepository(db));
+    }
+
+    [Test]
+    public async Task GetTopAsync_returns_null_entry_info_when_no_run()
+    {
+        var (db, runRepo) = await SetupAsync();
+        await using var _ = db;
+        var svc = BuildService(db, runRepo);
+
+        var dto = await svc.GetTopAsync(viewerId: 99);
+        Assert.That(dto.EntryInfo, Is.Null);
+        Assert.That(dto.ClassInfo, Is.Null);
+        Assert.That(dto.DeckInfo, Is.Null);
+    }
+
+    [Test]
+    public async Task GetTopAsync_after_entry_omits_class_info_and_deck_info()
+    {
+        var (db, runRepo) = await SetupAsync();
+        await using var _ = db;
+        await runRepo.UpsertAsync(new ViewerArenaTwoPickRun
+        {
+            ViewerId = 99, EntryId = 1234, RewardScheduleId = 1, ChallengeId = 1,
+            MaxBattleCount = 7, ClassId = 0,
+            CandidateClassIdsJson = "[1,7,8]",
+            CreatedAt = DateTime.UtcNow, UpdatedAt = DateTime.UtcNow,
+        });
+        var svc = BuildService(db, runRepo);
+
+        var dto = await svc.GetTopAsync(viewerId: 99);
+        Assert.That(dto.EntryInfo, Is.Not.Null);
+        Assert.That(dto.EntryInfo!.Id, Is.EqualTo(1234));
+        Assert.That(dto.ClassInfo, Is.Null);
+        Assert.That(dto.DeckInfo, Is.Null);
+        Assert.That(dto.BattleResults!.WinCount, Is.EqualTo(0));
+    }
+
+    [Test]
+    public async Task GetTopAsync_during_card_select_emits_class_and_deck_info()
+    {
+        var (db, runRepo) = await SetupAsync();
+        await using var _ = db;
+        await runRepo.UpsertAsync(new ViewerArenaTwoPickRun
+        {
+            ViewerId = 99, EntryId = 1234, MaxBattleCount = 7, ClassId = 1, LeaderSkinId = 1,
+            CandidateClassIdsJson = "[1,7,8]",
+            SelectTurn = 5, IsSelectCompleted = false,
+            SelectedCardIdsJson = "[100111010,100121010,100131010,100141010,100114010,100124010,100134010,100144010]",
+            CreatedAt = DateTime.UtcNow, UpdatedAt = DateTime.UtcNow,
+        });
+        var svc = BuildService(db, runRepo);
+
+        var dto = await svc.GetTopAsync(viewerId: 99);
+        Assert.That(dto.ClassInfo, Is.Not.Null);
+        Assert.That(dto.ClassInfo!.ClassId1, Is.EqualTo(1));
+        Assert.That(dto.DeckInfo, Is.Not.Null);
+        Assert.That(dto.DeckInfo!.SelectTurn, Is.EqualTo(5));
+        Assert.That(dto.DeckInfo.SelectedCardIds.Count, Is.EqualTo(8));
+    }
+
+    private static IArenaTwoPickService BuildService(SVSimDbContext db, IArenaTwoPickRunRepository runRepo)
+    {
+        // GetTopAsync only uses _runs — every other dep can be null! because the test path
+        // never touches them. The 9th positional arg (db) is required from Task 13 onward.
+        return new ArenaTwoPickService(runRepo, null!, null!, null!, null!, null!, null!, null!, db);
+    }
+}