Handle split Publish batches in the trigger-link conformance test

A valid Publish response can contain the linked sampling item before the trigger item. Collect both handles with the existing bounded helper instead of asserting on one response. Cover unlimited and single-notification batches; the latter reproduces the CI failure without timing assumptions.

tests/Opc.Ua.Subscriptions.Tests/MonitorTriggeringTests.cs

@@ -225,10 +225,13 @@ namespace Opc.Ua.Subscriptions.Tests
             }
         }
 
-        [Test]
-        public async Task SimpleTriggerAddLinkAfterCreationAsync()
+        /// <summary>
+        /// A link added after item creation reports both items even when Publish splits their notifications.
+        /// </summary>
+        [TestCase(0u)]
+        [TestCase(1u)]
+        public async Task SimpleTriggerAddLinkAfterCreationAsync(uint maxNotificationsPerPublish)
         {
-            // Create both items first, then SetTriggering
             NodeId nodeA = VariableIds.Server_ServerStatus_CurrentTime;
             NodeId nodeB = ToNodeId(Constants.ScalarStaticInt32);
 
@@ -244,6 +247,11 @@ namespace Opc.Ua.Subscriptions.Tests
             // Items exist but no triggering link yet
             await ConsumeAllNotificationsAsync().ConfigureAwait(false);
 
+            ModifySubscriptionResponse modifyResp = await Session.ModifySubscriptionAsync(
+                null, m_subscriptionId, 100, 100, 10, maxNotificationsPerPublish, 0, CancellationToken.None)
+                .ConfigureAwait(false);
+            Assert.That(StatusCode.IsGood(modifyResp.ResponseHeader.ServiceResult), Is.True);
+
             // Now add the link
             SetTriggeringResponse trigResp =
                 await SetTriggerAsync(idA, [idB]).ConfigureAwait(false);
@@ -255,10 +263,10 @@ namespace Opc.Ua.Subscriptions.Tests
             await WriteValueAsync(nodeB,
                 UnsecureRandom.Shared.Next(1, 10000)).ConfigureAwait(false);
 
-            // A fires (CurrentTime), should trigger B
-            PublishResponse pubResp = await PublishAndWaitAsync().ConfigureAwait(false);
-            HashSet<uint> handles = CollectNotifiedHandles(pubResp);
-            Assert.That(handles, Does.Contain(1u));
+            // A and its linked item can arrive in different Publish responses.
+            HashSet<uint> handles = await PublishUntilHandlesObservedAsync([1u, 2u]).ConfigureAwait(false);
+            Assert.That(handles, Does.Contain(1u), "The trigger item must report.");
+            Assert.That(handles, Does.Contain(2u), "The newly linked sampling item must report after its trigger.");
         }
 
         [Test]