diff --git a/SVSim.UnitTests/BattleNode/Lifecycle/TypedBodyWireShapeTests.cs b/SVSim.UnitTests/BattleNode/Lifecycle/TypedBodyWireShapeTests.cs
new file mode 100644
index 0000000..3a63a51
--- /dev/null
+++ b/SVSim.UnitTests/BattleNode/Lifecycle/TypedBodyWireShapeTests.cs
@@ -0,0 +1,134 @@
+using System.Text.Json.Nodes;
+using NUnit.Framework;
+using SVSim.BattleNode.Lifecycle;
+using SVSim.BattleNode.Protocol;
+
+namespace SVSim.UnitTests.BattleNode.Lifecycle;
+
+/// <summary>
+/// Wire-shape regression tests: compare <see cref="MsgEnvelope.ToJson"/> output against
+/// JSON literals derived from captured prod frames in
+/// data_dumps/captures/battle-traffic_tk2_regular.ndjson. Per the feedback_wire_shape_tests
+/// memory, these are literal-comparison tests — NOT self-symmetric round-trips — so they
+/// catch the failure mode where a C# property is renamed and silently breaks the wire
+/// contract.
+/// </summary>
+[TestFixture]
+public class TypedBodyWireShapeTests
+{
+    [Test]
+    public void BuildMatched_SerializesAllWireKeysExpectedByTheClient()
+    {
+        var env = ScriptedLifecycle.BuildMatched(
+            playerViewerId: 906243102, opponentViewerId: 847666884, battleId: "597830888107");
+
+        var json = MsgEnvelope.ToJson(env);
+        var node = JsonNode.Parse(json)!.AsObject();
+
+        // Top-level envelope fields:
+        Assert.That(node["uri"]!.GetValue<string>(), Is.EqualTo("Matched"));
+        Assert.That(node["viewerId"]!.GetValue<long>(), Is.EqualTo(999_999_999L));
+        Assert.That(node["uuid"]!.GetValue<string>(), Is.EqualTo("node-stub"));
+        Assert.That(node["bid"]!.GetValue<string>(), Is.EqualTo("597830888107"));
+        Assert.That(node["try"]!.GetValue<int>(), Is.EqualTo(0));
+        Assert.That(node["cat"]!.GetValue<int>(), Is.EqualTo(1));
+        Assert.That(node["resultCode"]!.GetValue<int>(), Is.EqualTo(1));
+
+        // Inner selfInfo block has the wire keys the client's Parse looks up.
+        var selfInfo = node["selfInfo"]!.AsObject();
+        foreach (var key in new[] {
+            "country_code", "userName", "sleeveId", "emblemId", "degreeId",
+            "fieldId", "isOfficial", "oppoId", "seed",
+        })
+        {
+            Assert.That(selfInfo.ContainsKey(key), Is.True, $"selfInfo missing wire key '{key}'");
+        }
+        Assert.That(selfInfo["oppoId"]!.GetValue<long>(), Is.EqualTo(847666884L));
+        Assert.That(selfInfo.ContainsKey("oppoDeckCount"), Is.False, "selfInfo must NOT have oppoDeckCount");
+
+        var oppoInfo = node["oppoInfo"]!.AsObject();
+        Assert.That(oppoInfo["oppoDeckCount"]!.GetValue<int>(), Is.EqualTo(30));
+        Assert.That(oppoInfo["oppoId"]!.GetValue<long>(), Is.EqualTo(906243102L));
+
+        var selfDeck = node["selfDeck"]!.AsArray();
+        Assert.That(selfDeck.Count, Is.EqualTo(30));
+        Assert.That(selfDeck[0]!.AsObject()["idx"]!.GetValue<int>(), Is.EqualTo(1));
+        Assert.That(selfDeck[0]!.AsObject()["cardId"]!.GetValue<long>(), Is.EqualTo(100_011_010L));
+    }
+
+    [Test]
+    public void BuildBattleStart_SerializesAllWireKeysAndPreservesBattlePointAsymmetry()
+    {
+        var env = ScriptedLifecycle.BuildBattleStart(playerViewerId: 906243102);
+
+        var json = MsgEnvelope.ToJson(env);
+        var node = JsonNode.Parse(json)!.AsObject();
+
+        Assert.That(node["turnState"]!.GetValue<int>(), Is.EqualTo(0));
+        Assert.That(node["battleType"]!.GetValue<int>(), Is.EqualTo(11));
+        Assert.That(node["resultCode"]!.GetValue<int>(), Is.EqualTo(1));
+
+        var selfInfo = node["selfInfo"]!.AsObject();
+        Assert.That(selfInfo["rank"]!.GetValue<string>(), Is.EqualTo("10"));
+        Assert.That(selfInfo["battlePoint"]!.GetValue<string>(), Is.EqualTo("6270"));   // string on self
+        Assert.That(selfInfo["cardMasterName"]!.GetValue<string>(), Is.EqualTo("card_master_node_10015"));
+
+        var oppoInfo = node["oppoInfo"]!.AsObject();
+        Assert.That(oppoInfo["battlePoint"]!.GetValue<int>(), Is.EqualTo(0));            // int on oppo
+        Assert.That(oppoInfo["isMasterRank"]!.GetValue<string>(), Is.EqualTo("0"));
+        Assert.That(oppoInfo["masterPoint"]!.GetValue<string>(), Is.EqualTo("0"));
+    }
+
+    [Test]
+    public void BuildDeal_SerializesSelfAndOppoArraysWithPosIdxShape()
+    {
+        var env = ScriptedLifecycle.BuildDeal();
+        var json = MsgEnvelope.ToJson(env);
+        var node = JsonNode.Parse(json)!.AsObject();
+
+        var self = node["self"]!.AsArray();
+        Assert.That(self.Count, Is.EqualTo(3));
+        Assert.That(self[0]!.AsObject()["pos"]!.GetValue<int>(), Is.EqualTo(0));
+        Assert.That(self[0]!.AsObject()["idx"]!.GetValue<int>(), Is.EqualTo(1));
+
+        var oppo = node["oppo"]!.AsArray();
+        Assert.That(oppo.Count, Is.EqualTo(3));
+    }
+
+    [Test]
+    public void BuildSwapResponse_SerializesSelfWithoutOppo()
+    {
+        var env = ScriptedLifecycle.BuildSwapResponse(new long[] { 1, 4, 3 });
+        var json = MsgEnvelope.ToJson(env);
+        var node = JsonNode.Parse(json)!.AsObject();
+
+        Assert.That(node.ContainsKey("self"), Is.True);
+        Assert.That(node.ContainsKey("oppo"), Is.False);
+        Assert.That(node["self"]!.AsArray()[1]!.AsObject()["idx"]!.GetValue<int>(), Is.EqualTo(4));
+    }
+
+    [Test]
+    public void BuildReady_SerializesAllFieldsIncludingSeedAndSpin()
+    {
+        var env = ScriptedLifecycle.BuildReady(new long[] { 1, 4, 3 });
+        var json = MsgEnvelope.ToJson(env);
+        var node = JsonNode.Parse(json)!.AsObject();
+
+        Assert.That(node["idxChangeSeed"]!.GetValue<int>(), Is.EqualTo(771_335_280));
+        Assert.That(node["spin"]!.GetValue<int>(), Is.EqualTo(243));
+        Assert.That(node["self"]!.AsArray().Count, Is.EqualTo(3));
+        Assert.That(node["oppo"]!.AsArray().Count, Is.EqualTo(3));
+    }
+
+    [Test]
+    public void BuildOpponentTurnStart_SerializesSpinAndResultCode()
+    {
+        var env = ScriptedLifecycle.BuildOpponentTurnStart();
+        var json = MsgEnvelope.ToJson(env);
+        var node = JsonNode.Parse(json)!.AsObject();
+
+        Assert.That(node["spin"]!.GetValue<int>(), Is.EqualTo(100));
+        Assert.That(node["resultCode"]!.GetValue<int>(), Is.EqualTo(1));
+        Assert.That(node["uri"]!.GetValue<string>(), Is.EqualTo("TurnStart"));
+    }
+}