diff --git a/SVSim.BattleNode/Lifecycle/ScriptedLifecycle.cs b/SVSim.BattleNode/Lifecycle/ScriptedLifecycle.cs
index 4a2b499..71e287e 100644
--- a/SVSim.BattleNode/Lifecycle/ScriptedLifecycle.cs
+++ b/SVSim.BattleNode/Lifecycle/ScriptedLifecycle.cs
@@ -1,4 +1,5 @@
 using SVSim.BattleNode.Protocol;
+using SVSim.BattleNode.Protocol.Bodies;
 
 namespace SVSim.BattleNode.Lifecycle;
 
@@ -7,21 +8,9 @@ namespace SVSim.BattleNode.Lifecycle;
 /// (Matched / BattleStart / Deal / Swap response / Ready) plus a trivial opponent TurnStart
 /// the dispatch pushes after the player's TurnEnd. The values are templated from the TK2
 /// captures at <c>data_dumps/captures/battle-traffic_tk2_regular.ndjson</c> — anything
-/// hardcoded here came from a real prod frame.
+/// hardcoded here came from a real prod frame, with names + provenance in
+/// <see cref="ScriptedProfiles"/>.
 /// </summary>
-/// <remarks>
-/// <para>"Scripted" means the opponent never reacts to your plays. We push enough to land
-/// you on the mulligan screen, run a real mulligan exchange, give you turn 1, transition
-/// to "Opponent's turn…" after your <c>TurnEnd</c>, and then sit there indefinitely. This
-/// is the documented v1 stopping point.</para>
-/// <para>
-/// All builders go through <see cref="EnvelopeForPush"/>, which injects
-/// <c>resultCode = 1</c> into every body. The client's <c>OnReceived</c> drops any
-/// synchronize push whose <c>resultCode != Success</c> (absent counts as None=0); leaving
-/// it off silently breaks the state machine without surfacing an error.
-/// </para>
-/// <para>To make this less scripted: see the project README §"Where to extend".</para>
-/// </remarks>
 public static class ScriptedLifecycle
 {
     /// <summary>
@@ -29,7 +18,7 @@ public static class ScriptedLifecycle
     /// every card-master version we care about, so the client can render it without
     /// triggering a card-master-mismatch error.
     /// </summary>
-    public static readonly long DummyCardId = 100011010;
+    public const long DummyCardId = 100011010L;
 
     /// <summary>
     /// Viewer id we present as the opponent on every scripted push. Out-of-range vs. real
@@ -37,87 +26,27 @@ public static class ScriptedLifecycle
     /// </summary>
     public const long FakeOpponentViewerId = 999_999_999L;
 
-    public static MsgEnvelope BuildMatched(long playerViewerId, long opponentViewerId, string battleId)
-    {
-        var body = new Dictionary<string, object?>
-        {
-            ["selfInfo"] = new Dictionary<string, object?>
-            {
-                ["country_code"] = "KOR",
-                ["userName"] = "Player",
-                ["sleeveId"] = "3000011",
-                ["emblemId"] = "701441011",
-                ["degreeId"] = "300003",
-                ["fieldId"] = 43,
-                ["isOfficial"] = 0,
-                ["oppoId"] = opponentViewerId,
-                ["seed"] = 17548138L,
-            },
-            ["oppoInfo"] = new Dictionary<string, object?>
-            {
-                ["country_code"] = "JPN",
-                ["userName"] = "Opponent",
-                ["sleeveId"] = "704141010",
-                ["emblemId"] = "400001100",
-                ["degreeId"] = "120027",
-                ["fieldId"] = 5,
-                ["isOfficial"] = 0,
-                ["oppoId"] = playerViewerId,
-                ["seed"] = 17548138L,
-                ["oppoDeckCount"] = 30,
-            },
-            ["selfDeck"] = BuildDummyDeck(),
-        };
-        return EnvelopeForPush(NetworkBattleUri.Matched, body, bid: battleId);
-    }
+    public static MsgEnvelope BuildMatched(long playerViewerId, long opponentViewerId, string battleId) =>
+        EnvelopeForPush(NetworkBattleUri.Matched,
+            new MatchedBody(
+                SelfInfo: ScriptedProfiles.PlayerMatchedProfile with { OppoId = opponentViewerId },
+                OppoInfo: ScriptedProfiles.OpponentMatchedProfile with { OppoId = playerViewerId },
+                SelfDeck: BuildDummyDeck()),
+            bid: battleId);
 
-    public static MsgEnvelope BuildBattleStart(long playerViewerId)
-    {
-        var body = new Dictionary<string, object?>
-        {
-            ["turnState"] = 0,             // player goes first
-            ["battleType"] = 11,           // TK2 NetworkBattleType
-            ["selfInfo"] = new Dictionary<string, object?>
-            {
-                ["rank"] = "10",
-                ["battlePoint"] = "6270",
-                ["classId"] = "1",
-                ["charaId"] = "1",
-                ["cardMasterName"] = "card_master_node_10015",
-            },
-            ["oppoInfo"] = new Dictionary<string, object?>
-            {
-                ["rank"] = "1",
-                ["isMasterRank"] = "0",
-                ["battlePoint"] = 0,
-                ["masterPoint"] = "0",
-                ["classId"] = "8",
-                ["charaId"] = "8",
-                ["cardMasterName"] = "card_master_node_10015",
-            },
-        };
-        return EnvelopeForPush(NetworkBattleUri.BattleStart, body);
-    }
+    public static MsgEnvelope BuildBattleStart(long playerViewerId) =>
+        EnvelopeForPush(NetworkBattleUri.BattleStart,
+            new BattleStartBody(
+                TurnState: 0,    // player goes first
+                BattleType: 11,  // TK2 NetworkBattleType
+                SelfInfo: ScriptedProfiles.PlayerBattleStartProfile,
+                OppoInfo: ScriptedProfiles.OpponentBattleStartProfile));
 
-    public static MsgEnvelope BuildDeal()
-    {
-        var body = new Dictionary<string, object?>
-        {
-            ["self"] = new List<object?>
-            {
-                new Dictionary<string, object?> { ["pos"] = 0, ["idx"] = 1 },
-                new Dictionary<string, object?> { ["pos"] = 1, ["idx"] = 2 },
-                new Dictionary<string, object?> { ["pos"] = 2, ["idx"] = 3 },
-            },
-            ["oppo"] = new List<object?>
-            {
-                new Dictionary<string, object?> { ["pos"] = 0, ["idx"] = 1 },
-                new Dictionary<string, object?> { ["pos"] = 1, ["idx"] = 2 },
-                new Dictionary<string, object?> { ["pos"] = 2, ["idx"] = 3 },
-            },
-        };
-        return EnvelopeForPush(NetworkBattleUri.Deal, body);
-    }
+    public static MsgEnvelope BuildDeal() =>
+        EnvelopeForPush(NetworkBattleUri.Deal,
+            new DealBody(
+                Self: new[] { new PosIdx(0, 1), new PosIdx(1, 2), new PosIdx(2, 3) },
+                Oppo: new[] { new PosIdx(0, 1), new PosIdx(1, 2), new PosIdx(2, 3) }));
 
     /// <summary>
     /// Initial 3-card hand idxs from <see cref="BuildDeal"/>. Each position in this array
@@ -144,81 +73,55 @@ public static class ScriptedLifecycle
         return hand;
     }
 
-    public static MsgEnvelope BuildSwapResponse(IReadOnlyList<long> hand)
-    {
-        var body = new Dictionary<string, object?>
-        {
-            ["self"] = BuildPosIdxList(hand),
-        };
-        return EnvelopeForPush(NetworkBattleUri.Swap, body);
-    }
+    public static MsgEnvelope BuildSwapResponse(IReadOnlyList<long> hand) =>
+        EnvelopeForPush(NetworkBattleUri.Swap,
+            new SwapResponseBody(Self: BuildPosIdxList(hand)));
 
-    public static MsgEnvelope BuildReady(IReadOnlyList<long> hand)
-    {
-        var body = new Dictionary<string, object?>
-        {
-            ["self"] = BuildPosIdxList(hand),
-            // Opponent hand stays at the static 3 cards for v1.
-            ["oppo"] = BuildPosIdxList(InitialHand),
-            ["idxChangeSeed"] = 771335280,
-            ["spin"] = 243,
-        };
-        return EnvelopeForPush(NetworkBattleUri.Ready, body);
-    }
+    public static MsgEnvelope BuildReady(IReadOnlyList<long> hand) =>
+        EnvelopeForPush(NetworkBattleUri.Ready,
+            new ReadyBody(
+                Self: BuildPosIdxList(hand),
+                Oppo: BuildPosIdxList(InitialHand),
+                IdxChangeSeed: ScriptedProfiles.ReadyIdxChangeSeed,
+                Spin: ScriptedProfiles.ReadySpin));
 
     /// <summary>
     /// Generic TurnStart push used to transition the client into "Opponent's turn…" state
     /// after the player's TurnEnd. v1 doesn't simulate the opponent — once this lands the
     /// client sits at the opponent-turn display indefinitely.
     /// </summary>
-    public static MsgEnvelope BuildOpponentTurnStart()
-    {
-        var body = new Dictionary<string, object?>
-        {
-            ["spin"] = 100,
-        };
-        return EnvelopeForPush(NetworkBattleUri.TurnStart, body);
-    }
+    public static MsgEnvelope BuildOpponentTurnStart() =>
+        EnvelopeForPush(NetworkBattleUri.TurnStart,
+            new OpponentTurnStartBody(Spin: ScriptedProfiles.OpponentTurnStartSpin));
 
-    private static List<object?> BuildPosIdxList(IReadOnlyList<long> hand)
+    private static IReadOnlyList<PosIdx> BuildPosIdxList(IReadOnlyList<long> hand)
     {
-        var list = new List<object?>(hand.Count);
+        var list = new List<PosIdx>(hand.Count);
         for (var pos = 0; pos < hand.Count; pos++)
         {
-            list.Add(new Dictionary<string, object?> { ["pos"] = pos, ["idx"] = (int)hand[pos] });
+            list.Add(new PosIdx(Pos: pos, Idx: (int)hand[pos]));
         }
         return list;
     }
 
-    private static List<object?> BuildDummyDeck()
+    private static IReadOnlyList<DeckCardRef> BuildDummyDeck()
     {
-        var deck = new List<object?>(30);
+        var deck = new List<DeckCardRef>(30);
         for (var i = 1; i <= 30; i++)
         {
-            deck.Add(new Dictionary<string, object?>
-            {
-                ["idx"] = i,
-                ["cardId"] = DummyCardId,
-            });
+            deck.Add(new DeckCardRef(Idx: i, CardId: DummyCardId));
         }
         return deck;
     }
 
-    private static MsgEnvelope EnvelopeForPush(NetworkBattleUri uri, Dictionary<string, object?> body, string? bid = null)
-    {
-        // Synchronize-push routing in the client's OnReceived drops any frame whose
-        // resultCode != Success (1). Absent counts as 0 (None) and is also dropped — so we
-        // MUST include it on every scripted push, not just InitNetwork ack / BattleFinish.
-        // See server-to-client.md §"Routing in OnReceived" and the matching prod captures.
-        body["resultCode"] = (int)ReceiveNodeResultCode.Success;
-        return new MsgEnvelope(uri,
+    private static MsgEnvelope EnvelopeForPush(NetworkBattleUri uri, IMsgBody body, string? bid = null) =>
+        new(uri,
             ViewerId: FakeOpponentViewerId,
             Uuid: "node-stub",
             Bid: bid,
             Try: 0,
             Cat: EmitCategory.Battle,
             PubSeq: null,
-            PlaySeq: null,         // OutboundSequencer.AssignAndArchive stamps this
+            PlaySeq: null,
             Body: body);
-    }
 }
diff --git a/SVSim.BattleNode/Protocol/MsgEnvelope.cs b/SVSim.BattleNode/Protocol/MsgEnvelope.cs
index bfe25df..d5398b4 100644
--- a/SVSim.BattleNode/Protocol/MsgEnvelope.cs
+++ b/SVSim.BattleNode/Protocol/MsgEnvelope.cs
@@ -1,12 +1,13 @@
 using System.Text.Json;
+using System.Text.Json.Nodes;
 using System.Text.Json.Serialization;
 
 namespace SVSim.BattleNode.Protocol;
 
 /// <summary>
-/// The shared envelope on every encrypted msg / synchronize frame. Body is opaque
-/// (Dictionary&lt;string, object?&gt;) because shape varies per Uri — typed register-action
-/// models come in a later slice.
+/// The shared envelope on every encrypted msg / synchronize frame. Body is
+/// <see cref="IMsgBody"/> — either a typed body record (outbound) or a
+/// <see cref="RawBody"/> (inbound).
 /// </summary>
 public sealed record MsgEnvelope(
     NetworkBattleUri Uri,
@@ -17,7 +18,7 @@ public sealed record MsgEnvelope(
     EmitCategory Cat,
     long? PubSeq,
     long? PlaySeq,
-    Dictionary<string, object?> Body)
+    IMsgBody Body)
 {
     private static readonly JsonSerializerOptions Options = CreateOptions();
 
@@ -30,9 +31,10 @@ public sealed record MsgEnvelope(
     {
         var opt = new JsonSerializerOptions
         {
-            // Wire-key casing here is bare camelCase — NOT EmulatedEntrypoint's snake_case policy.
+            // Wire-key casing is bare camelCase via per-field [JsonPropertyName] —
+            // NOT EmulatedEntrypoint's snake_case policy. The naming-policy line
+            // that was here previously was dead code (every wire key is explicit).
             DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull,
-            PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
         };
         opt.Converters.Add(new JsonStringEnumConverter());
         return opt;
@@ -40,26 +42,76 @@ public sealed record MsgEnvelope(
 
     public static string ToJson(MsgEnvelope env)
     {
-        var doc = new Dictionary<string, object?>
+        JsonObject result;
+        if (env.Body is RawBody raw)
         {
-            ["uri"] = env.Uri.ToString(),
-            ["viewerId"] = env.ViewerId,
-            ["uuid"] = env.Uuid,
-            ["try"] = env.Try,
-            ["cat"] = (int)env.Cat,
-        };
-        if (env.Bid is not null) doc["bid"] = env.Bid;
-        if (env.PubSeq.HasValue) doc["pubSeq"] = env.PubSeq.Value;
-        if (env.PlaySeq.HasValue) doc["playSeq"] = env.PlaySeq.Value;
-        foreach (var (k, v) in env.Body)
-        {
-            if (ReservedEnvelopeKeys.Contains(k))
-                throw new ArgumentException(
-                    $"Body key '{k}' collides with a reserved envelope field. Move it to a typed field on MsgEnvelope.",
-                    nameof(env));
-            doc[k] = v;
+            // Inbound-echo path: flatten Entries to top-level keys, same as before
+            // the typed-body refactor.
+            result = new JsonObject();
+            foreach (var (k, v) in raw.Entries)
+            {
+                if (ReservedEnvelopeKeys.Contains(k))
+                    throw new ArgumentException(
+                        $"RawBody key '{k}' collides with a reserved envelope field. " +
+                        $"Move it to a typed field on MsgEnvelope.",
+                        nameof(env));
+                result[k] = ToJsonNode(v);
+            }
         }
-        return JsonSerializer.Serialize(doc, Options);
+        else
+        {
+            // Typed body: serialize via [JsonPropertyName] attributes on the record.
+            result = (JsonObject)JsonSerializer.SerializeToNode(env.Body, env.Body.GetType(), Options)!;
+        }
+
+        result["uri"] = env.Uri.ToString();
+        result["viewerId"] = env.ViewerId;
+        result["uuid"] = env.Uuid;
+        result["try"] = env.Try;
+        result["cat"] = (int)env.Cat;
+        if (env.Bid is not null) result["bid"] = env.Bid;
+        if (env.PubSeq.HasValue) result["pubSeq"] = env.PubSeq.Value;
+        if (env.PlaySeq.HasValue) result["playSeq"] = env.PlaySeq.Value;
+
+        return result.ToJsonString(Options);
+    }
+
+    /// <summary>
+    /// Convert a boxed CLR value (as stored in <see cref="RawBody.Entries"/>) to a JsonNode.
+    /// Explicit type switch on the runtime type — `JsonValue.Create(object?)` would create
+    /// a `JsonValueCustomized&lt;object&gt;` that requires a TypeInfoResolver at serialize time
+    /// (introduced in S.T.Json 8.0 source-gen mode).
+    /// </summary>
+    private static JsonNode? ToJsonNode(object? value) => value switch
+    {
+        null => null,
+        string s => JsonValue.Create(s),
+        bool b => JsonValue.Create(b),
+        long l => JsonValue.Create(l),
+        int i => JsonValue.Create(i),
+        double d => JsonValue.Create(d),
+        decimal m => JsonValue.Create(m),
+        // Inbound-parsed nested objects come through as Dictionary<string, object?>; nested
+        // arrays as List<object?>. FromJson is the source of these shapes — see ToObject.
+        IDictionary<string, object?> dict => DictToJsonObject(dict),
+        IReadOnlyList<object?> list => ListToJsonArray(list),
+        _ => throw new InvalidOperationException(
+            $"RawBody contains a value of unsupported type {value.GetType().FullName}. " +
+            "Only primitives, nested dicts (object), and nested lists are recognized."),
+    };
+
+    private static JsonObject DictToJsonObject(IDictionary<string, object?> dict)
+    {
+        var obj = new JsonObject();
+        foreach (var (k, v) in dict) obj[k] = ToJsonNode(v);
+        return obj;
+    }
+
+    private static JsonArray ListToJsonArray(IReadOnlyList<object?> list)
+    {
+        var arr = new JsonArray();
+        foreach (var v in list) arr.Add(ToJsonNode(v));
+        return arr;
     }
 
     public static MsgEnvelope FromJson(string json)
@@ -76,14 +128,14 @@ public sealed record MsgEnvelope(
         var pubSeq = root.TryGetProperty("pubSeq", out var psEl) ? psEl.GetInt64() : (long?)null;
         var playSeq = root.TryGetProperty("playSeq", out var plsEl) ? plsEl.GetInt64() : (long?)null;
 
-        var body = new Dictionary<string, object?>();
+        var bodyDict = new Dictionary<string, object?>();
         foreach (var prop in root.EnumerateObject())
         {
             if (ReservedEnvelopeKeys.Contains(prop.Name)) continue;
-            body[prop.Name] = ToObject(prop.Value);
+            bodyDict[prop.Name] = ToObject(prop.Value);
         }
 
-        return new MsgEnvelope(uri, viewerId, uuid, bid, @try, cat, pubSeq, playSeq, body);
+        return new MsgEnvelope(uri, viewerId, uuid, bid, @try, cat, pubSeq, playSeq, new RawBody(bodyDict));
     }
 
     private static object? ToObject(JsonElement el) => el.ValueKind switch
diff --git a/SVSim.BattleNode/Reliability/Gungnir.cs b/SVSim.BattleNode/Reliability/Gungnir.cs
index c1644e7..3e28158 100644
--- a/SVSim.BattleNode/Reliability/Gungnir.cs
+++ b/SVSim.BattleNode/Reliability/Gungnir.cs
@@ -3,7 +3,10 @@ namespace SVSim.BattleNode.Reliability;
 /// <summary>
 /// Body builders for the alive channel. The timer/loop that drives 5s emits lives on
 /// BattleSession; this class is just the pure body-shape factory.
-/// v1 always reports scs/ocs=ONLINE — real disconnect detection is deferred.
+/// v1 always reports scs/ocs=ONLINE — real disconnect detection is deferred. The push
+/// body itself is constructed inline in BattleSession.HandleAliveEventAsync using
+/// AlivePushBody; only the emit body (sent by us TO the client on the alive channel,
+/// currently unused in v1) remains here.
 /// </summary>
 public static class Gungnir
 {
@@ -14,10 +17,4 @@ public static class Gungnir
         ["currentSeq"] = tracker.HighWaterMark,
         // actionSeq omitted in v1 — no turn-transition flag yet.
     };
-
-    public static Dictionary<string, object?> BuildAlivePushBody() => new()
-    {
-        ["scs"] = "ONLINE",
-        ["ocs"] = "ONLINE",
-    };
 }
diff --git a/SVSim.BattleNode/Sessions/BattleSession.cs b/SVSim.BattleNode/Sessions/BattleSession.cs
index 043afda..fbab589 100644
--- a/SVSim.BattleNode/Sessions/BattleSession.cs
+++ b/SVSim.BattleNode/Sessions/BattleSession.cs
@@ -4,6 +4,7 @@ using System.Text;
 using Microsoft.Extensions.Logging;
 using SVSim.BattleNode.Lifecycle;
 using SVSim.BattleNode.Protocol;
+using SVSim.BattleNode.Protocol.Bodies;
 using SVSim.BattleNode.Reliability;
 using SVSim.BattleNode.Wire;
 
@@ -169,7 +170,7 @@ public sealed class BattleSession
                 Cat: EmitCategory.General,
                 PubSeq: null,
                 PlaySeq: null,
-                Body: Gungnir.BuildAlivePushBody());
+                Body: new AlivePushBody(Scs: "ONLINE", Ocs: "ONLINE"));
             await PushNoStockAsync(aliveEnv, eventName: "alive");
         }
         catch (Exception ex)
@@ -263,7 +264,7 @@ public sealed class BattleSession
         Cat: EmitCategory.General,
         PubSeq: null,
         PlaySeq: null,
-        Body: new Dictionary<string, object?> { ["resultCode"] = 1 });
+        Body: new ResultCodeOnlyBody());
 
     private MsgEnvelope BuildBattleFinishNoContest() => new(
         NetworkBattleUri.BattleFinish,
@@ -274,7 +275,7 @@ public sealed class BattleSession
         Cat: EmitCategory.Battle,
         PubSeq: null,
         PlaySeq: null,
-        Body: new Dictionary<string, object?> { ["result"] = 1, ["resultCode"] = 1 });
+        Body: new BattleFinishBody(Result: ScriptedProfiles.BattleResultPlayerWins));
 
     private static IReadOnlyList<long> ExtractIdxList(MsgEnvelope env)
     {
@@ -282,7 +283,8 @@ public sealed class BattleSession
         // string). MsgEnvelope.FromJson should box small ints as long, but a parser quirk
         // anywhere upstream could yield a different boxed type and OfType<long> would silently
         // drop the entries — that broke the v1 mulligan during smoke.
-        if (env.Body.TryGetValue("idxList", out var raw) && raw is System.Collections.IEnumerable seq && raw is not string)
+        if (env.Body is not RawBody rawBody) return Array.Empty<long>();
+        if (rawBody.Entries.TryGetValue("idxList", out var raw) && raw is System.Collections.IEnumerable seq && raw is not string)
         {
             var result = new List<long>();
             foreach (var item in seq)
diff --git a/SVSim.UnitTests/BattleNode/Integration/BattleNodeFlowTests.cs b/SVSim.UnitTests/BattleNode/Integration/BattleNodeFlowTests.cs
index df99569..be89b4c 100644
--- a/SVSim.UnitTests/BattleNode/Integration/BattleNodeFlowTests.cs
+++ b/SVSim.UnitTests/BattleNode/Integration/BattleNodeFlowTests.cs
@@ -66,7 +66,7 @@ public class BattleNodeFlowTests
             Cat: uri == NetworkBattleUri.InitNetwork ? EmitCategory.General
                  : uri == NetworkBattleUri.InitBattle ? EmitCategory.Matching
                  : EmitCategory.Battle,
-            PubSeq: pubSeq, PlaySeq: null, Body: body ?? new Dictionary<string, object?>());
+            PubSeq: pubSeq, PlaySeq: null, Body: new RawBody(body ?? new Dictionary<string, object?>()));
 
     private static string MakeKey()
     {
diff --git a/SVSim.UnitTests/BattleNode/Lifecycle/ScriptedLifecycleTests.cs b/SVSim.UnitTests/BattleNode/Lifecycle/ScriptedLifecycleTests.cs
index f9ca3d9..c232553 100644
--- a/SVSim.UnitTests/BattleNode/Lifecycle/ScriptedLifecycleTests.cs
+++ b/SVSim.UnitTests/BattleNode/Lifecycle/ScriptedLifecycleTests.cs
@@ -1,6 +1,7 @@
 using NUnit.Framework;
 using SVSim.BattleNode.Lifecycle;
 using SVSim.BattleNode.Protocol;
+using SVSim.BattleNode.Protocol.Bodies;
 
 namespace SVSim.UnitTests.BattleNode.Lifecycle;
 
@@ -13,40 +14,39 @@ public class ScriptedLifecycleTests
         var env = ScriptedLifecycle.BuildMatched(playerViewerId: 906243102, opponentViewerId: 847666884, battleId: "b");
 
         Assert.That(env.Uri, Is.EqualTo(NetworkBattleUri.Matched));
-        var selfInfo = (Dictionary<string, object?>)env.Body["selfInfo"]!;
-        Assert.That(selfInfo["oppoId"], Is.EqualTo(847666884L));
-        var oppoInfo = (Dictionary<string, object?>)env.Body["oppoInfo"]!;
-        Assert.That(oppoInfo["oppoId"], Is.EqualTo(906243102L));
+        var body = (MatchedBody)env.Body;
+        Assert.That(body.SelfInfo.OppoId, Is.EqualTo(847666884L));
+        Assert.That(body.OppoInfo.OppoId, Is.EqualTo(906243102L));
 
-        // Bid travels in the envelope, not the Body — protect against the Task 5 reserved-keys regression.
+        // Bid travels in the envelope, not the Body — protect against the reserved-keys regression.
         Assert.That(env.Bid, Is.EqualTo("b"));
-        Assert.That(env.Body.ContainsKey("bid"), Is.False);
+        // Typed bodies can't carry an envelope-level "bid" key by construction (no such property).
     }
 
     [Test]
     public void BuildMatched_ContainsThirtyCardSelfDeck()
     {
         var env = ScriptedLifecycle.BuildMatched(1, 2, "b");
-        var deck = (List<object?>)env.Body["selfDeck"]!;
-        Assert.That(deck.Count, Is.EqualTo(30));
+        var body = (MatchedBody)env.Body;
+        Assert.That(body.SelfDeck.Count, Is.EqualTo(30));
     }
 
     [Test]
     public void BuildBattleStart_HasTurnStateZeroAndBattleTypeEleven()
     {
         var env = ScriptedLifecycle.BuildBattleStart(playerViewerId: 1);
-        Assert.That(env.Body["turnState"], Is.EqualTo(0));
-        Assert.That(env.Body["battleType"], Is.EqualTo(11));
+        var body = (BattleStartBody)env.Body;
+        Assert.That(body.TurnState, Is.EqualTo(0));
+        Assert.That(body.BattleType, Is.EqualTo(11));
     }
 
     [Test]
     public void BuildDeal_HasThreeSelfAndThreeOppoEntries()
     {
         var env = ScriptedLifecycle.BuildDeal();
-        var self = (List<object?>)env.Body["self"]!;
-        var oppo = (List<object?>)env.Body["oppo"]!;
-        Assert.That(self.Count, Is.EqualTo(3));
-        Assert.That(oppo.Count, Is.EqualTo(3));
+        var body = (DealBody)env.Body;
+        Assert.That(body.Self.Count, Is.EqualTo(3));
+        Assert.That(body.Oppo.Count, Is.EqualTo(3));
     }
 
     [Test]
@@ -75,19 +75,19 @@ public class ScriptedLifecycleTests
     public void BuildSwapResponse_RendersGivenHandAsPositions()
     {
         var env = ScriptedLifecycle.BuildSwapResponse(new long[] { 1, 4, 3 });
-        var self = (List<object?>)env.Body["self"]!;
-        Assert.That(self.Count, Is.EqualTo(3));
-        Assert.That(((Dictionary<string, object?>)self[1]!)["idx"], Is.EqualTo(4));
+        var body = (SwapResponseBody)env.Body;
+        Assert.That(body.Self.Count, Is.EqualTo(3));
+        Assert.That(body.Self[1].Idx, Is.EqualTo(4));
     }
 
     [Test]
     public void BuildReady_IncludesIdxChangeSeedAndSpin_AndUsesGivenHand()
     {
         var env = ScriptedLifecycle.BuildReady(new long[] { 1, 4, 3 });
-        Assert.That(env.Body.ContainsKey("idxChangeSeed"), Is.True);
-        Assert.That(env.Body.ContainsKey("spin"), Is.True);
-        var self = (List<object?>)env.Body["self"]!;
-        Assert.That(((Dictionary<string, object?>)self[1]!)["idx"], Is.EqualTo(4));
+        var body = (ReadyBody)env.Body;
+        Assert.That(body.IdxChangeSeed, Is.EqualTo(771_335_280));
+        Assert.That(body.Spin, Is.EqualTo(243));
+        Assert.That(body.Self[1].Idx, Is.EqualTo(4));
     }
 
     [Test]
@@ -95,6 +95,7 @@ public class ScriptedLifecycleTests
     {
         var env = ScriptedLifecycle.BuildOpponentTurnStart();
         Assert.That(env.Uri, Is.EqualTo(NetworkBattleUri.TurnStart));
-        Assert.That(env.Body.ContainsKey("spin"), Is.True);
+        var body = (OpponentTurnStartBody)env.Body;
+        Assert.That(body.Spin, Is.EqualTo(100));
     }
 }
diff --git a/SVSim.UnitTests/BattleNode/Protocol/MsgEnvelopeTests.cs b/SVSim.UnitTests/BattleNode/Protocol/MsgEnvelopeTests.cs
index 5e53342..abb8d27 100644
--- a/SVSim.UnitTests/BattleNode/Protocol/MsgEnvelopeTests.cs
+++ b/SVSim.UnitTests/BattleNode/Protocol/MsgEnvelopeTests.cs
@@ -1,4 +1,3 @@
-using System.Text.Json;
 using NUnit.Framework;
 using SVSim.BattleNode.Protocol;
 
@@ -19,7 +18,8 @@ public class MsgEnvelopeTests
 
         var env = MsgEnvelope.FromJson(json);
 
-        var idxList = (List<object?>)env.Body["idxList"]!;
+        var raw = (RawBody)env.Body;
+        var idxList = (List<object?>)raw.Entries["idxList"]!;
         Assert.That(idxList.Count, Is.EqualTo(2));
         Assert.That(idxList[0], Is.TypeOf<long>(), "idxList[0] must be boxed long, not double.");
         Assert.That(idxList[0], Is.EqualTo(2L));
@@ -39,7 +39,7 @@ public class MsgEnvelopeTests
             Cat: EmitCategory.General,
             PubSeq: null,
             PlaySeq: null,
-            Body: new Dictionary<string, object?> { ["foo"] = 42 });
+            Body: new RawBody(new Dictionary<string, object?> { ["foo"] = 42 }));
 
         var json = MsgEnvelope.ToJson(env);
         var back = MsgEnvelope.FromJson(json);
@@ -49,7 +49,7 @@ public class MsgEnvelopeTests
         Assert.That(back.Uuid, Is.EqualTo("udid-1234"));
         Assert.That(back.Bid, Is.EqualTo("597830888107"));
         Assert.That(back.Cat, Is.EqualTo(EmitCategory.General));
-        Assert.That(back.Body["foo"], Is.EqualTo(42L));   // JsonElement → int64
+        Assert.That(((RawBody)back.Body).Entries["foo"], Is.EqualTo(42L));
     }
 
     [Test]
@@ -64,7 +64,7 @@ public class MsgEnvelopeTests
             Cat: EmitCategory.Battle,
             PubSeq: null,
             PlaySeq: 5,
-            Body: new Dictionary<string, object?>());
+            Body: new RawBody(new Dictionary<string, object?>()));
 
         var json = MsgEnvelope.ToJson(env);
 
@@ -85,7 +85,7 @@ public class MsgEnvelopeTests
     }
 
     [Test]
-    public void ToJson_BodyContainingReservedKey_Throws()
+    public void ToJson_RawBodyContainingReservedKey_Throws()
     {
         var env = new MsgEnvelope(
             Uri: NetworkBattleUri.Loaded,
@@ -96,7 +96,7 @@ public class MsgEnvelopeTests
             Cat: EmitCategory.Battle,
             PubSeq: null,
             PlaySeq: null,
-            Body: new Dictionary<string, object?> { ["uri"] = "Injected" });
+            Body: new RawBody(new Dictionary<string, object?> { ["uri"] = "Injected" }));
 
         var ex = Assert.Throws<ArgumentException>(() => MsgEnvelope.ToJson(env));
         Assert.That(ex!.Message, Does.Contain("uri"));
@@ -114,7 +114,7 @@ public class MsgEnvelopeTests
             Cat: EmitCategory.Battle,
             PubSeq: null,
             PlaySeq: null,
-            Body: new Dictionary<string, object?>());
+            Body: new RawBody(new Dictionary<string, object?>()));
 
         var json = MsgEnvelope.ToJson(env);
 
diff --git a/SVSim.UnitTests/BattleNode/Protocol/MsgPayloadCodecTests.cs b/SVSim.UnitTests/BattleNode/Protocol/MsgPayloadCodecTests.cs
index afbfb75..fc2b9ef 100644
--- a/SVSim.UnitTests/BattleNode/Protocol/MsgPayloadCodecTests.cs
+++ b/SVSim.UnitTests/BattleNode/Protocol/MsgPayloadCodecTests.cs
@@ -24,7 +24,7 @@ public class MsgPayloadCodecTests
             Cat: EmitCategory.Battle,
             PubSeq: 3,
             PlaySeq: null,
-            Body: new Dictionary<string, object?>());
+            Body: new RawBody(new Dictionary<string, object?>()));
 
         var bytes = MsgPayloadCodec.Encode(env, key: FreshKey());
         var back = MsgPayloadCodec.Decode(bytes);
@@ -48,6 +48,6 @@ public class MsgPayloadCodecTests
 
         Assert.That(env.Uri, Is.EqualTo(NetworkBattleUri.InitNetwork));
         Assert.That(env.Cat, Is.EqualTo(EmitCategory.General));
-        Assert.That(env.Body["resultCode"], Is.EqualTo(1L));
+        Assert.That(((RawBody)env.Body).Entries["resultCode"], Is.EqualTo(1L));
     }
 }
diff --git a/SVSim.UnitTests/BattleNode/Reliability/GungnirTests.cs b/SVSim.UnitTests/BattleNode/Reliability/GungnirTests.cs
index 40ea1b5..628a257 100644
--- a/SVSim.UnitTests/BattleNode/Reliability/GungnirTests.cs
+++ b/SVSim.UnitTests/BattleNode/Reliability/GungnirTests.cs
@@ -6,14 +6,6 @@ namespace SVSim.UnitTests.BattleNode.Reliability;
 [TestFixture]
 public class GungnirTests
 {
-    [Test]
-    public void BuildAlivePush_AlwaysReturnsScsOnlineOcsOnline()
-    {
-        var body = Gungnir.BuildAlivePushBody();
-        Assert.That(body["scs"], Is.EqualTo("ONLINE"));
-        Assert.That(body["ocs"], Is.EqualTo("ONLINE"));
-    }
-
     [Test]
     public void BuildAliveEmit_CarriesCurrentSeqFromTracker()
     {
diff --git a/SVSim.UnitTests/BattleNode/Reliability/OutboundSequencerTests.cs b/SVSim.UnitTests/BattleNode/Reliability/OutboundSequencerTests.cs
index 21e0698..d27c570 100644
--- a/SVSim.UnitTests/BattleNode/Reliability/OutboundSequencerTests.cs
+++ b/SVSim.UnitTests/BattleNode/Reliability/OutboundSequencerTests.cs
@@ -9,7 +9,7 @@ public class OutboundSequencerTests
 {
     private static MsgEnvelope MakeEnvelope(NetworkBattleUri uri) =>
         new(uri, ViewerId: 1, Uuid: "u", Bid: null, Try: 0, Cat: EmitCategory.Battle,
-            PubSeq: null, PlaySeq: null, Body: new Dictionary<string, object?>());
+            PubSeq: null, PlaySeq: null, Body: new RawBody(new Dictionary<string, object?>()));
 
     [Test]
     public void AssignAndArchive_FirstCall_ReturnsEnvelopeWithPlaySeq1()
diff --git a/SVSim.UnitTests/BattleNode/Sessions/BattleSessionDispatchTests.cs b/SVSim.UnitTests/BattleNode/Sessions/BattleSessionDispatchTests.cs
index 4fff4eb..50b28ce 100644
--- a/SVSim.UnitTests/BattleNode/Sessions/BattleSessionDispatchTests.cs
+++ b/SVSim.UnitTests/BattleNode/Sessions/BattleSessionDispatchTests.cs
@@ -2,6 +2,7 @@
 using Microsoft.Extensions.Logging.Abstractions;
 using NUnit.Framework;
 using SVSim.BattleNode.Protocol;
+using SVSim.BattleNode.Protocol.Bodies;
 using SVSim.BattleNode.Sessions;
 
 namespace SVSim.UnitTests.BattleNode.Sessions;
@@ -17,7 +18,7 @@ public class BattleSessionDispatchTests
 
     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 Dictionary<string, object?>());
+            PubSeq: null, PlaySeq: null, Body: new RawBody(new Dictionary<string, object?>()));
 
     [Test]
     public void InitNetwork_PushesAckOnly_TransitionsToAwaitingInitBattle()
@@ -58,18 +59,22 @@ public class BattleSessionDispatchTests
         s.ComputeResponses(NewEnvelope(NetworkBattleUri.InitNetwork));
         s.ComputeResponses(NewEnvelope(NetworkBattleUri.InitBattle));
         s.ComputeResponses(NewEnvelope(NetworkBattleUri.Loaded));
-        var swapEnv = NewEnvelope(NetworkBattleUri.Swap);
         // Simulate the client's Swap{idxList:[2]}: the dict shape produced by MsgEnvelope.FromJson
-        // (a List<object?> of boxed long values).
-        swapEnv.Body["idxList"] = new List<object?> { 2L };
+        // (a List<object?> of boxed long values), wrapped in a RawBody as the inbound type.
+        var swapEnv = new MsgEnvelope(
+            NetworkBattleUri.Swap, ViewerId: 1, Uuid: "u", Bid: null, Try: 0,
+            Cat: EmitCategory.Battle, PubSeq: null, PlaySeq: null,
+            Body: new RawBody(new Dictionary<string, object?>
+            {
+                ["idxList"] = new List<object?> { 2L },
+            }));
 
         var responses = s.ComputeResponses(swapEnv);
 
-        var swapBody = responses[0].Envelope.Body;
-        var self = (List<object?>)swapBody["self"]!;
-        Assert.That(((Dictionary<string, object?>)self[0]!)["idx"], Is.EqualTo(1));
-        Assert.That(((Dictionary<string, object?>)self[1]!)["idx"], Is.EqualTo(4));  // swapped — fresh deck idx
-        Assert.That(((Dictionary<string, object?>)self[2]!)["idx"], Is.EqualTo(3));
+        var swapBody = (SwapResponseBody)responses[0].Envelope.Body;
+        Assert.That(swapBody.Self[0].Idx, Is.EqualTo(1));
+        Assert.That(swapBody.Self[1].Idx, Is.EqualTo(4));  // swapped — fresh deck idx
+        Assert.That(swapBody.Self[2].Idx, Is.EqualTo(3));
     }
 
     [Test]