diff --git a/SVSim.BattleNode/Bridge/IMatchingBridge.cs b/SVSim.BattleNode/Bridge/IMatchingBridge.cs
index bc41966..3a3f577 100644
--- a/SVSim.BattleNode/Bridge/IMatchingBridge.cs
+++ b/SVSim.BattleNode/Bridge/IMatchingBridge.cs
@@ -3,10 +3,10 @@ namespace SVSim.BattleNode.Bridge;
 public interface IMatchingBridge
 {
     /// <summary>
-    /// Mint a battle id, register a pending session for the given viewer, and return the
-    /// URL the client should open a socket to.
+    /// Mint a battle id, register a pending session for the given viewer with their per-battle
+    /// MatchContext snapshot, and return the URL the client should open a socket to.
     /// </summary>
-    PendingMatch RegisterPendingBattle(long viewerId);
+    PendingMatch RegisterPendingBattle(long viewerId, MatchContext context);
 }
 
 public sealed record PendingMatch(string BattleId, string NodeServerUrl);
diff --git a/SVSim.BattleNode/Bridge/MatchingBridge.cs b/SVSim.BattleNode/Bridge/MatchingBridge.cs
index 2d4e419..706c2d4 100644
--- a/SVSim.BattleNode/Bridge/MatchingBridge.cs
+++ b/SVSim.BattleNode/Bridge/MatchingBridge.cs
@@ -21,7 +21,7 @@ public sealed class MatchingBridge : IMatchingBridge
         _options = options;
     }
 
-    public PendingMatch RegisterPendingBattle(long viewerId)
+    public PendingMatch RegisterPendingBattle(long viewerId, MatchContext context)
     {
         // 12-digit decimal battle id mirrors the captures (e.g. "975695075012").
         // Two unbiased 6-digit draws concatenated — RandomNumberGenerator.GetInt32 uses
@@ -31,7 +31,7 @@ public sealed class MatchingBridge : IMatchingBridge
         var hi = RandomNumberGenerator.GetInt32(0, 1_000_000);
         var lo = RandomNumberGenerator.GetInt32(0, 1_000_000);
         var battleId = $"{hi:D6}{lo:D6}";
-        _store.RegisterPending(new PendingBattle(battleId, viewerId));
+        _store.RegisterPending(new PendingBattle(battleId, viewerId, context));
         return new PendingMatch(battleId, _options.NodeServerUrl);
     }
 }
diff --git a/SVSim.BattleNode/Hosting/BattleNodeWebSocketHandler.cs b/SVSim.BattleNode/Hosting/BattleNodeWebSocketHandler.cs
index dc3a1fa..79e81f1 100644
--- a/SVSim.BattleNode/Hosting/BattleNodeWebSocketHandler.cs
+++ b/SVSim.BattleNode/Hosting/BattleNodeWebSocketHandler.cs
@@ -104,7 +104,7 @@ public sealed class BattleNodeWebSocketHandler
 
         var ws = await ctx.WebSockets.AcceptWebSocketAsync();
         _store.RemovePending(battleId);
-        var session = new BattleSession(ws, battleId, viewerId, _loggerFactory.CreateLogger<BattleSession>());
+        var session = new BattleSession(ws, battleId, viewerId, pending.Context, _loggerFactory.CreateLogger<BattleSession>());
         await session.RunAsync(ctx.RequestAborted);
     }
 
diff --git a/SVSim.BattleNode/Sessions/BattleSession.cs b/SVSim.BattleNode/Sessions/BattleSession.cs
index 43b89c9..0e62791 100644
--- a/SVSim.BattleNode/Sessions/BattleSession.cs
+++ b/SVSim.BattleNode/Sessions/BattleSession.cs
@@ -2,6 +2,7 @@ using System.Net.WebSockets;
 using System.Security.Cryptography;
 using System.Text;
 using Microsoft.Extensions.Logging;
+using SVSim.BattleNode.Bridge;
 using SVSim.BattleNode.Lifecycle;
 using SVSim.BattleNode.Protocol;
 using SVSim.BattleNode.Protocol.Bodies;
@@ -37,12 +38,19 @@ public sealed class BattleSession
     public InboundTracker Inbound { get; } = new();
     public OutboundSequencer Outbound { get; } = new();
 
-    public BattleSession(WebSocket ws, string battleId, long viewerId, ILogger<BattleSession> log)
+    /// <summary>
+    /// Player-side snapshot captured at do_matching time. ScriptedLifecycle reads the player
+    /// half of Matched/BattleStart frames from here; opponent half stays in ScriptedProfiles.
+    /// </summary>
+    internal MatchContext Context { get; }
+
+    public BattleSession(WebSocket ws, string battleId, long viewerId, MatchContext context, ILogger<BattleSession> log)
     {
         _ws = ws;
         _log = log;
         BattleId = battleId;
         ViewerId = viewerId;
+        Context = context;
     }
 
     /// <summary>
diff --git a/SVSim.BattleNode/Sessions/PendingBattle.cs b/SVSim.BattleNode/Sessions/PendingBattle.cs
index 28dbb88..5a6bc0a 100644
--- a/SVSim.BattleNode/Sessions/PendingBattle.cs
+++ b/SVSim.BattleNode/Sessions/PendingBattle.cs
@@ -1,7 +1,10 @@
+using SVSim.BattleNode.Bridge;
+
 namespace SVSim.BattleNode.Sessions;
 
 /// <summary>
-/// Sparse pre-connect record: enough to validate the incoming WS connect and resolve
-/// the viewer. Full BattleSession is created on connect.
+/// Sparse pre-connect record: viewer id + the per-battle MatchContext snapshot. Enough to
+/// validate the incoming WS connect, resolve the viewer, and seed the BattleSession with the
+/// player-half lifecycle data. Full BattleSession is created on connect.
 /// </summary>
-public sealed record PendingBattle(string BattleId, long ViewerId);
+public sealed record PendingBattle(string BattleId, long ViewerId, MatchContext Context);
diff --git a/SVSim.EmulatedEntrypoint/Controllers/ArenaTwoPickBattleController.cs b/SVSim.EmulatedEntrypoint/Controllers/ArenaTwoPickBattleController.cs
index c2f2322..06d14d4 100644
--- a/SVSim.EmulatedEntrypoint/Controllers/ArenaTwoPickBattleController.cs
+++ b/SVSim.EmulatedEntrypoint/Controllers/ArenaTwoPickBattleController.cs
@@ -11,24 +11,37 @@ public class ArenaTwoPickBattleController : SVSimController
 {
     private readonly IArenaTwoPickService _svc;
     private readonly IMatchingBridge _matching;
+    private readonly IMatchContextBuilder _matchContextBuilder;
 
-    public ArenaTwoPickBattleController(IArenaTwoPickService svc, IMatchingBridge matching)
+    public ArenaTwoPickBattleController(
+        IArenaTwoPickService svc,
+        IMatchingBridge matching,
+        IMatchContextBuilder matchContextBuilder)
     {
         _svc = svc;
         _matching = matching;
+        _matchContextBuilder = matchContextBuilder;
     }
 
     [HttpPost("do_matching")]
-    public IActionResult DoMatching([FromBody] DoMatchingRequest req)
+    public async Task<IActionResult> DoMatching([FromBody] DoMatchingRequest req)
     {
         if (!TryGetViewerId(out var vid)) return Unauthorized();
-        var match = _matching.RegisterPendingBattle(vid);
-        return Ok(new DoMatchingResponseDto
+        try
         {
-            MatchingState = 3004,
-            BattleId = match.BattleId,
-            NodeServerUrl = match.NodeServerUrl,
-        });
+            var ctx = await _matchContextBuilder.BuildForTwoPickAsync(vid);
+            var match = _matching.RegisterPendingBattle(vid, ctx);
+            return Ok(new DoMatchingResponseDto
+            {
+                MatchingState = 3004,
+                BattleId = match.BattleId,
+                NodeServerUrl = match.NodeServerUrl,
+            });
+        }
+        catch (ArenaTwoPickException ex)
+        {
+            return BadRequest(new { error_code = ex.ErrorCode });
+        }
     }
 
     [HttpPost("finish")]
diff --git a/SVSim.UnitTests/BattleNode/Bridge/MatchingBridgeTests.cs b/SVSim.UnitTests/BattleNode/Bridge/MatchingBridgeTests.cs
index b4c7473..b37e5ce 100644
--- a/SVSim.UnitTests/BattleNode/Bridge/MatchingBridgeTests.cs
+++ b/SVSim.UnitTests/BattleNode/Bridge/MatchingBridgeTests.cs
@@ -12,14 +12,16 @@ public class MatchingBridgeTests
     {
         var store = new InMemoryBattleSessionStore();
         var bridge = new MatchingBridge(store, new BattleNodeOptions { NodeServerUrl = "localhost:5148/socket.io/" });
+        var ctx = FixtureCtx();
 
-        var match = bridge.RegisterPendingBattle(viewerId: 906243102);
+        var match = bridge.RegisterPendingBattle(viewerId: 906243102, context: ctx);
 
         Assert.That(match.NodeServerUrl, Is.EqualTo("localhost:5148/socket.io/"));
         Assert.That(match.BattleId, Is.Not.Empty);
         var pending = store.TryGetPending(match.BattleId);
         Assert.That(pending, Is.Not.Null);
         Assert.That(pending!.ViewerId, Is.EqualTo(906243102));
+        Assert.That(pending.Context, Is.SameAs(ctx));
     }
 
     [Test]
@@ -27,8 +29,8 @@ public class MatchingBridgeTests
     {
         var bridge = new MatchingBridge(new InMemoryBattleSessionStore(), new BattleNodeOptions());
 
-        var a = bridge.RegisterPendingBattle(1);
-        var b = bridge.RegisterPendingBattle(2);
+        var a = bridge.RegisterPendingBattle(1, FixtureCtx());
+        var b = bridge.RegisterPendingBattle(2, FixtureCtx());
 
         Assert.That(a.BattleId, Is.Not.EqualTo(b.BattleId));
     }
@@ -38,9 +40,16 @@ public class MatchingBridgeTests
     {
         var bridge = new MatchingBridge(new InMemoryBattleSessionStore(), new BattleNodeOptions());
 
-        var match = bridge.RegisterPendingBattle(viewerId: 1);
+        var match = bridge.RegisterPendingBattle(viewerId: 1, context: FixtureCtx());
 
         Assert.That(match.BattleId, Has.Length.EqualTo(12));
         Assert.That(match.BattleId, Does.Match("^[0-9]{12}$"));
     }
+
+    private static MatchContext FixtureCtx() => new(
+        SelfDeckCardIds: Enumerable.Range(1, 30).Select(i => 100_011_010L).ToList(),
+        ClassId: "1", CharaId: "1", CardMasterName: "card_master_node_10015",
+        CountryCode: "KOR", UserName: "Player", SleeveId: "3000011",
+        EmblemId: "701441011", DegreeId: "300003", FieldId: 43, IsOfficial: 0,
+        BattleType: 11);
 }
diff --git a/SVSim.UnitTests/BattleNode/Integration/BattleNodeFlowTests.cs b/SVSim.UnitTests/BattleNode/Integration/BattleNodeFlowTests.cs
index be89b4c..58216cf 100644
--- a/SVSim.UnitTests/BattleNode/Integration/BattleNodeFlowTests.cs
+++ b/SVSim.UnitTests/BattleNode/Integration/BattleNodeFlowTests.cs
@@ -14,10 +14,9 @@ public class BattleNodeFlowTests
 {
     /// <summary>
     /// End-to-end smoke for the v1 scripted lifecycle. Boots the EmulatedEntrypoint via
-    /// SVSimTestFactory (in-memory SQLite + reference-data CSV import), mints a battle
-    /// through IMatchingBridge, opens a raw Socket.IO v2 client against the in-process
-    /// TestServer, and drives InitNetwork → Loaded → Swap, asserting the right scripted
-    /// frames come back in order.
+    /// SVSimTestFactory, mints a battle through IMatchingBridge with a fixture MatchContext,
+    /// opens a raw Socket.IO v2 client against the in-process TestServer, and drives
+    /// InitNetwork → Loaded → Swap, asserting the right scripted frames come back in order.
     /// </summary>
     [Test]
     [Timeout(30000)]
@@ -28,11 +27,10 @@ public class BattleNodeFlowTests
 
         using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(15));
         var ct = cts.Token;
-        var pending = bridge.RegisterPendingBattle(viewerId: 906243102);
+        var pending = bridge.RegisterPendingBattle(viewerId: 906243102, context: FixtureCtx());
 
         var key = MakeKey();
         var encryptedVid = NodeCrypto.EncryptForNode("906243102", key);
-        // TestServer ignores the host portion of the URI — only the path + query route.
         var wsUri = new Uri($"ws://localhost/socket.io/?BattleId={pending.BattleId}&viewerId={Uri.EscapeDataString(encryptedVid)}&EIO=3&transport=websocket");
 
         var wsClient = factory.Server.CreateWebSocketClient();
@@ -40,20 +38,16 @@ public class BattleNodeFlowTests
         await using var client = new RawSocketIoTestClient(ws);
         await client.ConsumeHandshakeAsync(ct);
 
-        // 1. InitNetwork → expect InitNetwork ack push only.
         await client.SendMsgAsync(MakeEnvelope(NetworkBattleUri.InitNetwork, pubSeq: 1), key, ct);
         Assert.That((await client.ReceiveSynchronizeAsync(ct)).Uri, Is.EqualTo(NetworkBattleUri.InitNetwork));
 
-        // 2. InitBattle → expect Matched (handler is now subscribed on the client side).
         await client.SendMsgAsync(MakeEnvelope(NetworkBattleUri.InitBattle, pubSeq: 2), key, ct);
         Assert.That((await client.ReceiveSynchronizeAsync(ct)).Uri, Is.EqualTo(NetworkBattleUri.Matched));
 
-        // 3. Loaded → expect BattleStart + Deal.
         await client.SendMsgAsync(MakeEnvelope(NetworkBattleUri.Loaded, pubSeq: 3), key, ct);
         Assert.That((await client.ReceiveSynchronizeAsync(ct)).Uri, Is.EqualTo(NetworkBattleUri.BattleStart));
         Assert.That((await client.ReceiveSynchronizeAsync(ct)).Uri, Is.EqualTo(NetworkBattleUri.Deal));
 
-        // 4. Swap with empty idxList → expect Swap response + Ready.
         await client.SendMsgAsync(MakeEnvelope(NetworkBattleUri.Swap, pubSeq: 4,
             body: new Dictionary<string, object?> { ["idxList"] = new List<object?>() }), key, ct);
         Assert.That((await client.ReceiveSynchronizeAsync(ct)).Uri, Is.EqualTo(NetworkBattleUri.Swap));
@@ -62,7 +56,6 @@ public class BattleNodeFlowTests
 
     private static MsgEnvelope MakeEnvelope(NetworkBattleUri uri, long pubSeq, Dictionary<string, object?>? body = null) =>
         new(uri, ViewerId: 906243102, Uuid: "udid-test", Bid: null, Try: 0,
-            // EmitMsgPack: InitNetwork → general(99); other matching URIs → matching(2); else battle(1).
             Cat: uri == NetworkBattleUri.InitNetwork ? EmitCategory.General
                  : uri == NetworkBattleUri.InitBattle ? EmitCategory.Matching
                  : EmitCategory.Battle,
@@ -73,4 +66,11 @@ public class BattleNodeFlowTests
         var seq = 0;
         return NodeCrypto.GenerateKey(() => (seq++ * 13) % 16);
     }
+
+    internal static MatchContext FixtureCtx(IReadOnlyList<long>? deck = null) => new(
+        SelfDeckCardIds: deck ?? Enumerable.Range(1, 30).Select(i => 100_011_010L).ToList(),
+        ClassId: "1", CharaId: "1", CardMasterName: "card_master_node_10015",
+        CountryCode: "KOR", UserName: "Player", SleeveId: "3000011",
+        EmblemId: "701441011", DegreeId: "300003", FieldId: 43, IsOfficial: 0,
+        BattleType: 11);
 }
diff --git a/SVSim.UnitTests/BattleNode/Sessions/BattleSessionDispatchTests.cs b/SVSim.UnitTests/BattleNode/Sessions/BattleSessionDispatchTests.cs
index 50b28ce..35e01d5 100644
--- a/SVSim.UnitTests/BattleNode/Sessions/BattleSessionDispatchTests.cs
+++ b/SVSim.UnitTests/BattleNode/Sessions/BattleSessionDispatchTests.cs
@@ -1,6 +1,7 @@
 // SVSim.UnitTests/BattleNode/Sessions/BattleSessionDispatchTests.cs
 using Microsoft.Extensions.Logging.Abstractions;
 using NUnit.Framework;
+using SVSim.BattleNode.Bridge;
 using SVSim.BattleNode.Protocol;
 using SVSim.BattleNode.Protocol.Bodies;
 using SVSim.BattleNode.Sessions;
@@ -13,9 +14,16 @@ public class BattleSessionDispatchTests
     private static BattleSession NewSession()
     {
         // ws is unused by ComputeResponses; pass null! and rely on the test never invoking the pump.
-        return new BattleSession(ws: null!, battleId: "bid-1", viewerId: 1, log: NullLogger<BattleSession>.Instance);
+        return new BattleSession(ws: null!, battleId: "bid-1", viewerId: 1, context: FixtureCtx(), log: NullLogger<BattleSession>.Instance);
     }
 
+    private static MatchContext FixtureCtx() => new(
+        SelfDeckCardIds: Enumerable.Range(1, 30).Select(i => 100_011_010L).ToList(),
+        ClassId: "1", CharaId: "1", CardMasterName: "card_master_node_10015",
+        CountryCode: "KOR", UserName: "Player", SleeveId: "3000011",
+        EmblemId: "701441011", DegreeId: "300003", FieldId: 43, IsOfficial: 0,
+        BattleType: 11);
+
     private static MsgEnvelope NewEnvelope(NetworkBattleUri uri) =>
         new(uri, ViewerId: 1, Uuid: "u", Bid: null, Try: 0, Cat: EmitCategory.Battle,
             PubSeq: null, PlaySeq: null, Body: new RawBody(new Dictionary<string, object?>()));
diff --git a/SVSim.UnitTests/BattleNode/Sessions/BattleSessionPumpTests.cs b/SVSim.UnitTests/BattleNode/Sessions/BattleSessionPumpTests.cs
index 106accd..c173caa 100644
--- a/SVSim.UnitTests/BattleNode/Sessions/BattleSessionPumpTests.cs
+++ b/SVSim.UnitTests/BattleNode/Sessions/BattleSessionPumpTests.cs
@@ -4,6 +4,7 @@ using System.Text;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Logging.Abstractions;
 using NUnit.Framework;
+using SVSim.BattleNode.Bridge;
 using SVSim.BattleNode.Protocol;
 using SVSim.BattleNode.Sessions;
 using SVSim.BattleNode.Wire;
@@ -39,7 +40,7 @@ public class BattleSessionPumpTests
     {
         var ws = new TestWebSocket();
         var session = new BattleSession(
-            ws: ws, battleId: "bid-pump", viewerId: 906243102,
+            ws: ws, battleId: "bid-pump", viewerId: 906243102, context: FixtureCtx(),
             log: NullLogger<BattleSession>.Instance);
 
         using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(8));
@@ -84,7 +85,7 @@ public class BattleSessionPumpTests
     {
         var ws = new TestWebSocket();
         var session = new BattleSession(
-            ws: ws, battleId: "bid-cancel", viewerId: 906243102,
+            ws: ws, battleId: "bid-cancel", viewerId: 906243102, context: FixtureCtx(),
             log: NullLogger<BattleSession>.Instance);
 
         using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(8));
@@ -127,7 +128,7 @@ public class BattleSessionPumpTests
         var ws = new TestWebSocket();
         var logCapture = new CapturingLogger();
         var session = new BattleSession(
-            ws: ws, battleId: "bid-clip", viewerId: 906243102, log: logCapture);
+            ws: ws, battleId: "bid-clip", viewerId: 906243102, context: FixtureCtx(), log: logCapture);
 
         using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(8));
         var runTask = session.RunAsync(cts.Token);
@@ -208,6 +209,13 @@ public class BattleSessionPumpTests
         return NodeCrypto.GenerateKey(() => (seq++ * 7) % 16);
     }
 
+    private static MatchContext FixtureCtx() => new(
+        SelfDeckCardIds: Enumerable.Range(1, 30).Select(i => 100_011_010L).ToList(),
+        ClassId: "1", CharaId: "1", CardMasterName: "card_master_node_10015",
+        CountryCode: "KOR", UserName: "Player", SleeveId: "3000011",
+        EmblemId: "701441011", DegreeId: "300003", FieldId: 43, IsOfficial: 0,
+        BattleType: 11);
+
     private sealed class CapturingLogger : ILogger<BattleSession>
     {
         public List<string> Warnings { get; } = new();
diff --git a/SVSim.UnitTests/BattleNode/Sessions/InMemoryBattleSessionStoreTests.cs b/SVSim.UnitTests/BattleNode/Sessions/InMemoryBattleSessionStoreTests.cs
index 7582ea0..02d863f 100644
--- a/SVSim.UnitTests/BattleNode/Sessions/InMemoryBattleSessionStoreTests.cs
+++ b/SVSim.UnitTests/BattleNode/Sessions/InMemoryBattleSessionStoreTests.cs
@@ -1,4 +1,5 @@
 using NUnit.Framework;
+using SVSim.BattleNode.Bridge;
 using SVSim.BattleNode.Sessions;
 
 namespace SVSim.UnitTests.BattleNode.Sessions;
@@ -13,7 +14,7 @@ public class InMemoryBattleSessionStoreTests
     [Test]
     public void RegisterThenGet_ReturnsRegisteredBattle()
     {
-        var battle = new PendingBattle("bid-1", 906243102);
+        var battle = new PendingBattle("bid-1", 906243102, FixtureCtx());
         _store.RegisterPending(battle);
 
         Assert.That(_store.TryGetPending("bid-1"), Is.EqualTo(battle));
@@ -28,7 +29,7 @@ public class InMemoryBattleSessionStoreTests
     [Test]
     public void Remove_ReturnsTrueWhenPresent_FalseWhenAbsent()
     {
-        _store.RegisterPending(new PendingBattle("bid", 1));
+        _store.RegisterPending(new PendingBattle("bid", 1, FixtureCtx()));
         Assert.That(_store.RemovePending("bid"), Is.True);
         Assert.That(_store.RemovePending("bid"), Is.False);
     }
@@ -36,8 +37,15 @@ public class InMemoryBattleSessionStoreTests
     [Test]
     public void Register_DuplicateBattleId_OverwritesPrior()
     {
-        _store.RegisterPending(new PendingBattle("bid", 1));
-        _store.RegisterPending(new PendingBattle("bid", 2));
+        _store.RegisterPending(new PendingBattle("bid", 1, FixtureCtx()));
+        _store.RegisterPending(new PendingBattle("bid", 2, FixtureCtx()));
         Assert.That(_store.TryGetPending("bid")!.ViewerId, Is.EqualTo(2));
     }
+
+    private static MatchContext FixtureCtx() => new(
+        SelfDeckCardIds: Enumerable.Range(1, 30).Select(i => 100_011_010L).ToList(),
+        ClassId: "1", CharaId: "1", CardMasterName: "card_master_node_10015",
+        CountryCode: "KOR", UserName: "Player", SleeveId: "3000011",
+        EmblemId: "701441011", DegreeId: "300003", FieldId: 43, IsOfficial: 0,
+        BattleType: 11);
 }
diff --git a/SVSim.UnitTests/Controllers/ArenaTwoPickBattleControllerTests.cs b/SVSim.UnitTests/Controllers/ArenaTwoPickBattleControllerTests.cs
index 9aa6b4a..edee5e3 100644
--- a/SVSim.UnitTests/Controllers/ArenaTwoPickBattleControllerTests.cs
+++ b/SVSim.UnitTests/Controllers/ArenaTwoPickBattleControllerTests.cs
@@ -1,6 +1,9 @@
 using System.Net;
 using System.Net.Http.Json;
 using System.Text.Json;
+using Microsoft.Extensions.DependencyInjection;
+using SVSim.Database;
+using SVSim.Database.Models;
 using SVSim.UnitTests.Infrastructure;
 
 namespace SVSim.UnitTests.Controllers;
@@ -12,6 +15,8 @@ public class ArenaTwoPickBattleControllerTests
     {
         using var factory = new SVSimTestFactory();
         var viewerId = await factory.SeedViewerAsync();
+        await SeedCompleteTwoPickRunAsync(factory, viewerId);
+
         using var client = factory.CreateAuthenticatedClient(viewerId);
         var req = new {
             deck_no = 1L, need_init = 1, log = 1, excluded_field_id_list = new long[] { }, use_stage_select = 1, is_default_skin = 0,
@@ -28,12 +33,50 @@ public class ArenaTwoPickBattleControllerTests
         var battleId = root.GetProperty("battle_id").GetString();
         Assert.That(battleId, Is.Not.Null.And.Not.Empty);
         var nodeUrl = root.GetProperty("node_server_url").GetString();
-        // Matches prod wire format: host:port/socket.io/, no scheme prefix.
         Assert.That(nodeUrl, Does.Contain("/socket.io/"));
         Assert.That(nodeUrl, Does.Not.StartWith("ws://"));
         Assert.That(nodeUrl, Does.Not.StartWith("http://"));
-        // Required when matching_state ∈ {3004,3007,3011} per
-        // DoMatchingBase.SettingCardMasterId; client throws KeyNotFoundException without it.
         Assert.That(root.GetProperty("card_master_id").GetInt32(), Is.EqualTo(1));
     }
+
+    [Test]
+    public async Task DoMatching_NoActiveRun_Returns400WithErrorCode()
+    {
+        using var factory = new SVSimTestFactory();
+        var viewerId = await factory.SeedViewerAsync();
+        using var client = factory.CreateAuthenticatedClient(viewerId);
+        var req = new {
+            deck_no = 1L, need_init = 1, log = 1, excluded_field_id_list = new long[] { }, use_stage_select = 1, is_default_skin = 0,
+            viewer_id = "0", steam_id = 0, steam_session_ticket = "",
+        };
+        var resp = await client.PostAsync("/arena_two_pick_battle/do_matching", JsonContent.Create(req));
+
+        Assert.That(resp.StatusCode, Is.EqualTo(HttpStatusCode.BadRequest));
+        var body = await resp.Content.ReadAsStringAsync();
+        using var doc = JsonDocument.Parse(body);
+        Assert.That(doc.RootElement.GetProperty("error_code").GetString(),
+            Is.EqualTo("arena_two_pick_no_active_run"));
+    }
+
+    private static async Task SeedCompleteTwoPickRunAsync(SVSimTestFactory factory, long viewerId)
+    {
+        using var scope = factory.Services.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+        var deck = Enumerable.Range(1, 30).Select(i => 100_011_000L + i).ToList();
+        db.ViewerArenaTwoPickRuns.Add(new ViewerArenaTwoPickRun
+        {
+            ViewerId = viewerId,
+            EntryId = 1,
+            ClassId = 1,
+            LeaderSkinId = 1,
+            SelectedCardIdsJson = JsonSerializer.Serialize(deck),
+            IsSelectCompleted = true,
+            MaxBattleCount = 5,
+            CandidateClassIdsJson = "[1,2,3]",
+            PendingPickSetsJson = "[]",
+            ResultListJson = "[]",
+            NextCandidateId = 1,
+        });
+        await db.SaveChangesAsync();
+    }
 }