From 0764b8646f82b7aa1c0e2754815316efa81ce17a Mon Sep 17 00:00:00 2001
From: gamer147 <gamer147@gmail.com>
Date: Mon, 1 Jun 2026 11:11:31 -0400
Subject: [PATCH] feat(battle-node): capture session-scoped CT in
 BattleSession.RunAsync

---
 SVSim.BattleNode/Sessions/BattleSession.cs | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/SVSim.BattleNode/Sessions/BattleSession.cs b/SVSim.BattleNode/Sessions/BattleSession.cs
index fbab589..8ab6b03 100644
--- a/SVSim.BattleNode/Sessions/BattleSession.cs
+++ b/SVSim.BattleNode/Sessions/BattleSession.cs
@@ -18,6 +18,19 @@ public sealed class BattleSession
     private readonly WebSocket _ws;
     private readonly ILogger<BattleSession> _log;
 
+    /// <summary>
+    /// Cancellation token for the session lifetime, captured from <see cref="RunAsync"/>'s
+    /// parameter. Read by all send helpers so host shutdown promptly terminates pending
+    /// writes (was <c>CancellationToken.None</c> on every send pre-this-slice).
+    /// </summary>
+    /// <remarks>
+    /// Defaults to <see cref="CancellationToken.None"/> when <see cref="RunAsync"/> hasn't
+    /// run — e.g. unit tests that drive <see cref="ComputeResponses"/> directly without
+    /// going through the WS pump. None of those tests exercise send code, so the default
+    /// is safe.
+    /// </remarks>
+    private CancellationToken _sessionCt;
+
     public string BattleId { get; }
     public long ViewerId { get; }
     public BattleSessionPhase Phase { get; internal set; } = BattleSessionPhase.AwaitingInitNetwork;
@@ -37,6 +50,7 @@ public sealed class BattleSession
     /// </summary>
     public async Task RunAsync(CancellationToken cancellation)
     {
+        _sessionCt = cancellation;
         await SendEioOpenAsync(cancellation);
 
         var buffer = new byte[8192];