refactor(arena-tk2): FinishAsync returns RunFinishOutcome with WasFullClear signal

Introduces RunFinishOutcome — a semantic record that wraps the wire
FinishResponseDto with the controller-side WasFullClear signal used to fire
the challenge_full_clear mission event. The wire response isn't affected
(controller unwraps the .Response field before returning to the client);
RetireAsync stays returning FinishResponseDto because retire cannot full-clear.

Full-clear detection compares run.WinCount against ResolveMaxBattleCountAsync
rather than hard-coding 5, so a future TK2 rules-config change tracks
automatically. New test covers the full-clear signal explicitly.

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

SVSim.EmulatedEntrypoint/Controllers/ArenaTwoPickController.cs

@@ -49,7 +49,11 @@ public class ArenaTwoPickController : SVSimController
     public async Task<IActionResult> Finish([FromBody] FinishRequest _)
     {
         if (!TryGetViewerId(out var vid)) return Unauthorized();
-        return await GuardAsync(() => _svc.FinishAsync(vid));
+        return await GuardAsync(async () =>
+        {
+            var outcome = await _svc.FinishAsync(vid);
+            return outcome.Response;
+        });
     }
 
     private async Task<IActionResult> GuardAsync<T>(Func<Task<T>> action)

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

@@ -0,0 +1,9 @@
+namespace SVSim.EmulatedEntrypoint.Models.Dtos.Responses.ArenaTwoPick;
+
+/// <summary>
+/// What <see cref="Services.IArenaTwoPickService.FinishAsync(long)"/> returns to
+/// <c>ArenaTwoPickController.Finish</c>. The wire response is <see cref="Response"/>;
+/// <see cref="WasFullClear"/> is a controller-side signal for the
+/// <c>challenge_full_clear</c> mission emit and is never serialized.
+/// </summary>
+public sealed record RunFinishOutcome(FinishResponseDto Response, bool WasFullClear);

SVSim.EmulatedEntrypoint/Services/ArenaTwoPickService.cs

@@ -281,11 +281,27 @@ public class ArenaTwoPickService : IArenaTwoPickService
             }).ToList(),
         };
     }
-    public Task<FinishResponseDto> RetireAsync(long viewerId) => GrantRunRewardsAndDeleteAsync(viewerId, requireComplete: false);
+    public async Task<FinishResponseDto> RetireAsync(long viewerId)
+    {
+        var (response, _) = await GrantRunRewardsAndDeleteAsync(viewerId, requireComplete: false);
+        return response;
+    }
 
-    public Task<FinishResponseDto> FinishAsync(long viewerId) => GrantRunRewardsAndDeleteAsync(viewerId, requireComplete: true);
+    public async Task<RunFinishOutcome> FinishAsync(long viewerId)
+    {
+        var (response, winCount) = await GrantRunRewardsAndDeleteAsync(viewerId, requireComplete: true);
+        // TK2 is 5 battles per run; full clear == 5 wins == 0 losses. Reference the reward
+        // catalog's max WinCount rather than a magic 5 so a future rules-config change tracks.
+        int maxBattles = await ResolveMaxBattleCountAsync();
+        return new RunFinishOutcome(response, WasFullClear: winCount >= maxBattles);
+    }
 
-    private async Task<FinishResponseDto> GrantRunRewardsAndDeleteAsync(long viewerId, bool requireComplete)
+    /// <summary>
+    /// Grants rewards for the given run tier and deletes the run row. Returns the wire
+    /// response DTO plus the run's final WinCount — the latter feeds
+    /// <see cref="FinishAsync"/>'s full-clear detection but isn't exposed on the wire.
+    /// </summary>
+    private async Task<(FinishResponseDto Response, int WinCount)> GrantRunRewardsAndDeleteAsync(long viewerId, bool requireComplete)
     {
         var run = await _runs.GetByViewerIdAsync(viewerId)
             ?? throw new ArenaTwoPickException("arena_two_pick_no_active_run");
@@ -345,8 +361,9 @@ public class ArenaTwoPickService : IArenaTwoPickService
             .Select(g => new RewardEntryDto { RewardType = (int)g.RewardType, RewardId = g.RewardId, RewardNum = g.RewardNum })
             .ToList();
 
+        int winCountAtFinish = run.WinCount;
         await _runs.DeleteAsync(viewerId);
-        return new FinishResponseDto { Rewards = deltas, RewardList = postStates };
+        return (new FinishResponseDto { Rewards = deltas, RewardList = postStates }, winCountAtFinish);
     }
 
     private static SVSim.Database.Models.ArenaTwoPickReward WeightedPick(

SVSim.EmulatedEntrypoint/Services/IArenaTwoPickService.cs

@@ -9,7 +9,12 @@ public interface IArenaTwoPickService
     Task<ClassChooseResponseDto> ChooseClassAsync(long viewerId, int classId);
     Task<CardChooseResponseDto> ChooseCardAsync(long viewerId, long selectedId);
     Task<FinishResponseDto> RetireAsync(long viewerId);
-    Task<FinishResponseDto> FinishAsync(long viewerId);
+    /// <summary>
+    /// Ends a completed TK2 run (5 battles played) and grants the reward tier for
+    /// <c>run.WinCount</c>. Returns both the wire-shape rewards and a controller-side
+    /// signal for mission emit (<see cref="RunFinishOutcome.WasFullClear"/>).
+    /// </summary>
+    Task<RunFinishOutcome> FinishAsync(long viewerId);
     Task<BattleFinishResultDto> RecordBattleResultAsync(long viewerId, bool isWin);
 }