diff --git a/SVSim.BattleNode/Sessions/BattleSession.cs b/SVSim.BattleNode/Sessions/BattleSession.cs
index 0067345..ce9e2d4 100644
--- a/SVSim.BattleNode/Sessions/BattleSession.cs
+++ b/SVSim.BattleNode/Sessions/BattleSession.cs
@@ -86,6 +86,13 @@ public sealed class BattleSession
             catch { /* swallow */ }
         }
 
+        // Audit Md11 — release per-participant outbound archives at battle-end
+        // (only RealParticipant has one; bots don't archive). Heavy state is
+        // dropped synchronously here so the participant's TerminateAsync doesn't
+        // need to keep the dict alive through its disposal handshake.
+        if (A is RealParticipant rpA) rpA.Outbound.Clear();
+        if (B is RealParticipant rpB) rpB.Outbound.Clear();
+
         await Task.WhenAll(
             A.TerminateAsync(BattleFinishReason.NormalFinish),
             B.TerminateAsync(BattleFinishReason.NormalFinish))
diff --git a/SVSim.UnitTests/BattleNode/Sessions/BattleSessionTerminateCascadeTests.cs b/SVSim.UnitTests/BattleNode/Sessions/BattleSessionTerminateCascadeTests.cs
new file mode 100644
index 0000000..46f493c
--- /dev/null
+++ b/SVSim.UnitTests/BattleNode/Sessions/BattleSessionTerminateCascadeTests.cs
@@ -0,0 +1,59 @@
+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;
+using SVSim.BattleNode.Sessions.Participants;
+using SVSim.UnitTests.BattleNode.Infrastructure;
+
+namespace SVSim.UnitTests.BattleNode.Sessions;
+
+/// <summary>
+/// Audit Md11 — confirms <see cref="BattleSession.RunAsync"/> drops the per-RealParticipant
+/// <see cref="SVSim.BattleNode.Reliability.OutboundSequencer"/> archive when the session
+/// terminates. The Scripted bot has no outbound archive of its own, so the test uses a
+/// Scripted session (one Real, one ScriptedBot) and asserts only the Real side's archive
+/// is cleared.
+/// </summary>
+[TestFixture]
+public class BattleSessionTerminateCascadeTests
+{
+    [Test, Timeout(10_000)]
+    public async Task RunAsync_clears_real_participant_archive_on_terminate()
+    {
+        var ws = new TestWebSocket();
+        var real = new RealParticipant(
+            ws, viewerId: 1, MakeFakeContext(), NullLogger<RealParticipant>.Instance);
+        var bot = new ScriptedBotParticipant();
+
+        // Pre-load the archive so we can prove it was cleared (not just empty).
+        real.Outbound.AssignAndArchive(MakeEnvelope(NetworkBattleUri.Matched));
+        real.Outbound.AssignAndArchive(MakeEnvelope(NetworkBattleUri.BattleStart));
+        Assume.That(real.Outbound.Archive.Count, Is.EqualTo(2), "Precondition: archive populated.");
+
+        var session = new BattleSession(
+            battleId: "test-bid", type: BattleType.Scripted,
+            a: real, b: bot, log: NullLogger<BattleSession>.Instance);
+
+        // Drive RunAsync to completion: closing the incoming side causes
+        // RealParticipant's read loop to return Close → RunAsync exits → terminate
+        // cascade fires.
+        var runTask = session.RunAsync(CancellationToken.None);
+        ws.CompleteIncoming();
+        await runTask;
+
+        Assert.That(real.Outbound.Archive, Is.Empty,
+            "RealParticipant's outbound archive must be cleared by the terminate cascade.");
+    }
+
+    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 RawBody(new Dictionary<string, object?>()));
+
+    private static MatchContext MakeFakeContext() => new(
+        SelfDeckCardIds: Array.Empty<long>(),
+        ClassId: "1", CharaId: "1", CardMasterName: "card_master_node_10015",
+        CountryCode: "JP", UserName: "Test", SleeveId: "0",
+        EmblemId: "0", DegreeId: "0", FieldId: 0, IsOfficial: 0, BattleType: 11);
+}