Keep reusable MMS sessions alive after connect-operation cancellation

src/AR.Iec61850/Mms/MmsClientSession.ReceivePumpLifetime.cs

@@ -0,0 +1,50 @@
+namespace AR.Iec61850.Mms;
+
+public sealed partial class MmsClientSession
+{
+    /// <summary>
+    /// Rebinds the confirmed-service receive pump to the MMS association lifetime instead
+    /// of the cancellation token that was used only to establish the connection.
+    /// Call this when a long-lived session will be reused across multiple UI operations.
+    /// </summary>
+    public async Task RebindReceivePumpToSessionLifetimeAsync(
+        CancellationToken cancellationToken = default)
+    {
+        EnsureMmsReady();
+        cancellationToken.ThrowIfCancellationRequested();
+
+        if (_receivePump.PendingOperationCount != 0)
+        {
+            throw new InvalidOperationException(
+                "The MMS receive pump cannot be rebound while confirmed operations are pending.");
+        }
+
+        await MmsReceivePumpLifetimePolicy.RebindAsync(
+            _receivePump,
+            cancellationToken).ConfigureAwait(false);
+
+        if (!IsTransportConnected || !IsMmsInitiated || !_receivePump.IsRunning)
+        {
+            throw new InvalidOperationException(
+                "The MMS receive pump could not be rebound to the active association lifetime.");
+        }
+
+        LastReceiveRoutingSummary =
+            "MMS receive pump rebound to association-owned lifetime for reusable confirmed services.";
+    }
+}
+
+internal static class MmsReceivePumpLifetimePolicy
+{
+    public static async Task RebindAsync(
+        MmsReceivePump receivePump,
+        CancellationToken cancellationToken = default)
+    {
+        ArgumentNullException.ThrowIfNull(receivePump);
+        cancellationToken.ThrowIfCancellationRequested();
+
+        await receivePump.StopAsync().ConfigureAwait(false);
+        cancellationToken.ThrowIfCancellationRequested();
+        receivePump.Start();
+    }
+}

tests/AR.Iec61850.Tests/Mms/MmsReceivePumpLifetimePolicyTests.cs

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+using System.Threading.Channels;
+using AR.Iec61850.Asn1;
+using AR.Iec61850.Mms;
+
+namespace AR.Iec61850.Tests.Mms;
+
+public sealed class MmsReceivePumpLifetimePolicyTests
+{
+    [Fact]
+    public async Task Rebind_Detaches_Pump_From_Completed_Connect_Operation_Token()
+    {
+        var channel = Channel.CreateUnbounded<byte[]>();
+        var router = new MmsReceiveRouter();
+        var pump = new MmsReceivePump(
+            router,
+            cancellationToken => channel.Reader.ReadAsync(cancellationToken).AsTask());
+        using var connectOperation = new CancellationTokenSource();
+
+        pump.Start(connectOperation.Token);
+        await MmsReceivePumpLifetimePolicy.RebindAsync(pump);
+        connectOperation.Cancel();
+
+        using var pending = pump.RegisterConfirmedOperation(27);
+        await channel.Writer.WriteAsync(BuildConfirmedReadResponse(27));
+
+        using var timeout = new CancellationTokenSource(TimeSpan.FromSeconds(2));
+        var response = await pending.WaitAsync(timeout.Token);
+
+        Assert.True(pump.IsRunning);
+        Assert.Equal(MmsPduKind.ConfirmedResponse, response.Kind);
+        Assert.Equal(27, response.InvokeId);
+
+        await pump.StopAsync();
+    }
+
+    private static byte[] BuildConfirmedReadResponse(int invokeId)
+    {
+        var data = MmsDataCodec.Encode(MmsDataValue.Boolean(true));
+        var listOfAccessResult = BerWriter.EncodeTlv(0xA1, data);
+        var readService = BerWriter.EncodeTlv(0xA4, listOfAccessResult);
+        var mms = BerWriter.EncodeTlv(
+            0xA1,
+            BerWriter.EncodeTlv(0x02, BerWriter.EncodeSignedInteger(invokeId))
+                .Concat(readService)
+                .ToArray());
+
+        return MmsPresentation.WrapIsoPresentationPData(mms);
+    }
+}