diff --git a/apps/windows_agent/src/TermRemoteCtl.Agent/Terminal/HelperBackedConPtySession.cs b/apps/windows_agent/src/TermRemoteCtl.Agent/Terminal/HelperBackedConPtySession.cs
index 8aef90f..01ec45b 100644
--- a/apps/windows_agent/src/TermRemoteCtl.Agent/Terminal/HelperBackedConPtySession.cs
+++ b/apps/windows_agent/src/TermRemoteCtl.Agent/Terminal/HelperBackedConPtySession.cs
@@ -22,6 +22,7 @@ internal sealed class HelperBackedConPtySession : IConPtySession
     private StreamWriter? _commandWriter;
     private StreamReader? _outputReader;
     private Task? _outputPumpTask;
+    private readonly CancellationTokenSource _lifetime = new();
     private bool _started;
     private bool _disposed;
 
@@ -104,7 +105,7 @@ internal sealed class HelperBackedConPtySession : IConPtySession
             throw new InvalidOperationException($"Unexpected ConPTY helper startup handshake: {handshake}");
         }
 
-        _outputPumpTask = Task.Run(() => PumpOutputAsync(_outputReader, cancellationToken), cancellationToken);
+        _outputPumpTask = Task.Run(() => PumpOutputAsync(_outputReader, _lifetime.Token), CancellationToken.None);
         _started = true;
     }
 
@@ -149,6 +150,7 @@ internal sealed class HelperBackedConPtySession : IConPtySession
         }
 
         _disposed = true;
+        _lifetime.Cancel();
 
         if (_commandWriter is not null)
         {
@@ -182,6 +184,7 @@ internal sealed class HelperBackedConPtySession : IConPtySession
         _commandPipe?.Dispose();
         _outputPipe?.Dispose();
         _helperProcess?.Dispose();
+        _lifetime.Dispose();
     }
 
     private async Task PumpOutputAsync(StreamReader reader, CancellationToken cancellationToken)
diff --git a/apps/windows_agent/tests/TermRemoteCtl.Agent.IntegrationTests/Realtime/TerminalSmokeCheckTests.cs b/apps/windows_agent/tests/TermRemoteCtl.Agent.IntegrationTests/Realtime/TerminalSmokeCheckTests.cs
index 8b7aa8c..0a6ebff 100644
--- a/apps/windows_agent/tests/TermRemoteCtl.Agent.IntegrationTests/Realtime/TerminalSmokeCheckTests.cs
+++ b/apps/windows_agent/tests/TermRemoteCtl.Agent.IntegrationTests/Realtime/TerminalSmokeCheckTests.cs
@@ -44,6 +44,46 @@ public sealed class TerminalSmokeCheckTests
         }
     }
 
+    [Fact]
+    public async Task BuiltAgentExe_Reconnects_Existing_Terminal_And_Accepts_Input()
+    {
+        if (!OperatingSystem.IsWindows())
+        {
+            return;
+        }
+
+        await using var fixture = new BuiltAgentFixture();
+        await fixture.StartAsync();
+
+        try
+        {
+            var session = await fixture.CreateSessionAsync("smoke-reconnect");
+
+            using (var firstSocket = await fixture.ConnectTerminalAsync(session.SessionId))
+            {
+                _ = await fixture.ReceiveTextAsync(firstSocket, TimeSpan.FromSeconds(20));
+                await fixture.SendTextAsync(firstSocket, JsonSerializer.Serialize(new { type = "input", input = "Write-Output first\r" }));
+                _ = await fixture.ReceiveTextContainingAsync(firstSocket, "first", TimeSpan.FromSeconds(20));
+            }
+
+            using var secondSocket = await fixture.ConnectTerminalAsync(session.SessionId);
+            var attached = await fixture.ReceiveTextAsync(secondSocket, TimeSpan.FromSeconds(20));
+            var attachedPayload = JsonSerializer.Deserialize<TerminalAttachResponse>(attached, new JsonSerializerOptions(JsonSerializerDefaults.Web));
+            Assert.NotNull(attachedPayload);
+            Assert.Equal("attached", attachedPayload!.Type);
+            Assert.Equal(session.SessionId, attachedPayload.SessionId);
+
+            await fixture.SendTextAsync(secondSocket, JsonSerializer.Serialize(new { type = "input", input = "Write-Output second\r" }));
+            var output = await fixture.ReceiveTextContainingAsync(secondSocket, "second", TimeSpan.FromSeconds(20));
+
+            Assert.Contains("second", output, StringComparison.OrdinalIgnoreCase);
+        }
+        catch (Exception ex)
+        {
+            throw new InvalidOperationException($"{ex.Message}{Environment.NewLine}{fixture.GetDiagnostics()}", ex);
+        }
+    }
+
     private sealed class BuiltAgentFixture : IAsyncDisposable
     {
         private readonly string _projectRoot;