fix(abcip): budget expected reply size in RequestScheduler.TakeBatch (#582); private lock + struct-handle check across read fragments (#567)

Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy/NativeAbLegacyTagRuntime.cs

@@ -175,11 +175,15 @@ internal sealed class NativeAbLegacyTagRuntime : IAbLegacyTagRuntime
         return (Math.Max(1, PcccServices.MaxDataBytes / _elementSize), address);
     }
 
-    private async Task<ReadOnlyMemory<byte>> ExchangeAsync(Func<ushort, byte[]> pccc, CancellationToken ct)
+    /// <summary>Bytes of an Execute PCCC reply beyond its data: CIP header, requestor id, PCCC command / status / TNS
+    /// (rounded up) — the scheduler budgets <c>PcccReplyOverhead + data</c> against the connection (#582).</summary>
+    private const int PcccReplyOverhead = 32;
+
+    private async Task<ReadOnlyMemory<byte>> ExchangeAsync(Func<ushort, byte[]> pccc, CancellationToken ct, int replyDataBytes = 0)
     {
         var tns = unchecked((ushort)Interlocked.Increment(ref s_tns));
         var request = PcccServices.ExecutePccc(_vendor, _serial, pccc(tns));
-        var reply = await _scheduler.SendAsync(request, ct).ConfigureAwait(false);
+        var reply = await _scheduler.SendAsync(request, ct, expectedReplyBytes: PcccReplyOverhead + replyDataBytes).ConfigureAwait(false);
         return PcccServices.ParseReply(reply, tns, _requestorId);
     }
 
@@ -200,7 +204,7 @@ internal sealed class NativeAbLegacyTagRuntime : IAbLegacyTagRuntime
                 tns => plc5
                     ? PcccServices.Plc5RangeRead(tns, at, (ushort)(bytes / 2), bytes)
                     : PcccServices.SlcTypedRead(tns, at, bytes),
-                ct).ConfigureAwait(false);
+                ct, bytes).ConfigureAwait(false);
             if (data.Length < bytes)
                 throw new AbTransportException(AbStatus.BadReply, $"PCCC read returned {data.Length} of {bytes} bytes.");
             if (data.Length > bytes)