Eliminate PortTracker stub backlog by implementing Raft/file-store/stream/server/client/OCSP stubs and adding coverage. This makes all tracked stub features/tests executable and verified in the current porting phase.

dotnet/src/ZB.MOM.NatsNet.Server/Accounts/Account.cs

@@ -16,6 +16,7 @@
 using ZB.MOM.NatsNet.Server.Auth;
 using ZB.MOM.NatsNet.Server.Internal;
 using ZB.MOM.NatsNet.Server.Internal.DataStructures;
+using System.Text;
 
 namespace ZB.MOM.NatsNet.Server;
 
@@ -1643,7 +1644,50 @@ public sealed class Account : INatsAccount
     /// </summary>
     internal void UpdateLeafNodes(object sub, int delta)
     {
-        // TODO: session 15 — leaf node subscription propagation.
+        if (delta == 0 || sub is not Subscription s || s.Subject.Length == 0)
+            return;
+
+        var subject = Encoding.UTF8.GetString(s.Subject);
+        var queue = s.Queue is { Length: > 0 } ? Encoding.UTF8.GetString(s.Queue) : string.Empty;
+
+        _mu.EnterWriteLock();
+        try
+        {
+            _rm ??= new Dictionary<string, int>(StringComparer.Ordinal);
+            if (!_rm.TryGetValue(subject, out var rc))
+                rc = 0;
+            rc += delta;
+            if (rc <= 0)
+                _rm.Remove(subject);
+            else
+                _rm[subject] = rc;
+
+            if (!string.IsNullOrEmpty(queue))
+            {
+                _lqws ??= new Dictionary<string, int>(StringComparer.Ordinal);
+                var key = $"{subject} {queue}";
+                var qw = s.Qw != 0 ? s.Qw : 1;
+                if (!_lqws.TryGetValue(key, out var qv))
+                    qv = 0;
+                qv += delta * qw;
+                if (qv <= 0)
+                    _lqws.Remove(key);
+                else
+                    _lqws[key] = qv;
+            }
+        }
+        finally
+        {
+            _mu.ExitWriteLock();
+        }
+
+        List<ClientConnection> leafs;
+        _lmu.EnterReadLock();
+        try { leafs = [.. _lleafs]; }
+        finally { _lmu.ExitReadLock(); }
+
+        foreach (var leaf in leafs)
+            leaf.FlushSignal();
     }
 
     // -------------------------------------------------------------------------