feat(opcuaclient): subscription tuning, OperationLimits chunking, diagnostics counters, revocation options, DiscoveryUrl (#273 #275 #276 #277 #278)

Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe
2026-10-08 14:40:20 -04:00
parent 55eac5f68b
commit ba62022e88
12 changed files with 1308 additions and 100 deletions
@@ -0,0 +1,111 @@
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.OpcUaClient.Tests;
+
+/// <summary>#276 — counters are thread-safe and surface through <c>DriverHealth.Diagnostics</c>.</summary>
+[Trait("Category", "Unit")]
+public sealed class OpcUaClientDiagnosticsTests
+{
+    [Fact]
+    public void Fresh_snapshot_is_all_zero_with_the_full_key_set()
+    {
+        var snap = new OpcUaClientDiagnostics().Snapshot();
+
+        snap.Keys.ShouldBe(
+        [
+            "PublishResponseCount", "NotificationCount", "DataChangeCount", "BadStatusValueCount",
+            "PublishErrorCount", "KeepAliveMissCount", "ReconnectAttemptCount", "ReconnectSuccessCount",
+            "ReconnectExhaustedCount", "LastReconnectUtcTicks", "ReadCallCount", "ReadFailureCount",
+            "WriteCallCount", "WriteFailureCount", "ChunkedRequestCount",
+        ], ignoreOrder: true);
+        snap.Values.ShouldAllBe(v => v == 0);
+    }
+
+    [Fact]
+    public void Each_recorder_moves_exactly_its_own_counter()
+    {
+        var d = new OpcUaClientDiagnostics();
+        d.RecordPublishResponse();
+        d.RecordNotifications(3);
+        d.RecordDataChange(bad: false);
+        d.RecordDataChange(bad: true);
+        d.RecordPublishError();
+        d.RecordKeepAliveMiss();
+        d.RecordReconnectAttempt();
+        d.RecordReconnectSucceeded();
+        d.RecordReconnectExhausted();
+        d.RecordRead(failed: true);
+        d.RecordWrite(failed: false);
+        d.RecordChunkedRequest();
+
+        var s = d.Snapshot();
+        s["PublishResponseCount"].ShouldBe(1);
+        s["NotificationCount"].ShouldBe(3);
+        s["DataChangeCount"].ShouldBe(2);
+        s["BadStatusValueCount"].ShouldBe(1);
+        s["PublishErrorCount"].ShouldBe(1);
+        s["KeepAliveMissCount"].ShouldBe(1);
+        s["ReconnectAttemptCount"].ShouldBe(1);
+        s["ReconnectSuccessCount"].ShouldBe(1);
+        s["ReconnectExhaustedCount"].ShouldBe(1);
+        s["LastReconnectUtcTicks"].ShouldBeGreaterThan(0);
+        s["ReadCallCount"].ShouldBe(1);
+        s["ReadFailureCount"].ShouldBe(1);
+        s["WriteCallCount"].ShouldBe(1);
+        s["WriteFailureCount"].ShouldBe(0);
+        s["ChunkedRequestCount"].ShouldBe(1);
+    }
+
+    [Fact]
+    public void Concurrent_increments_do_not_lose_updates()
+    {
+        var d = new OpcUaClientDiagnostics();
+        const int threads = 8, each = 5_000;
+
+        Parallel.For(0, threads, _ =>
+        {
+            for (var i = 0; i < each; i++) { d.RecordDataChange(bad: i % 2 == 0); d.RecordNotifications(2); }
+        });
+
+        var s = d.Snapshot();
+        s["DataChangeCount"].ShouldBe(threads * each);
+        s["BadStatusValueCount"].ShouldBe(threads * each / 2);
+        s["NotificationCount"].ShouldBe(threads * each * 2);
+    }
+
+    [Fact]
+    public void Snapshot_is_a_point_in_time_copy()
+    {
+        var d = new OpcUaClientDiagnostics();
+        var before = d.Snapshot();
+        d.RecordKeepAliveMiss();
+
+        before["KeepAliveMissCount"].ShouldBe(0);
+        d.Snapshot()["KeepAliveMissCount"].ShouldBe(1);
+    }
+
+    [Fact]
+    public void GetHealth_carries_the_diagnostics_and_keeps_state_fields()
+    {
+        using var drv = new OpcUaClientDriver(new OpcUaClientDriverOptions(), "opcua-diag");
+        drv.DiagnosticsForTest.RecordKeepAliveMiss();
+        drv.DiagnosticsForTest.RecordKeepAliveMiss();
+
+        var h = drv.GetHealth();
+
+        h.State.ShouldBe(DriverState.Unknown);
+        h.Diagnostics.ShouldNotBeNull();
+        h.Diagnostics!["KeepAliveMissCount"].ShouldBe(2);
+    }
+
+    [Fact]
+    public void DriverHealth_without_diagnostics_stays_back_compatible()
+    {
+        var h = new DriverHealth(DriverState.Healthy, null, null);
+
+        h.Diagnostics.ShouldBeNull();
+        h.ShouldBe(new DriverHealth(DriverState.Healthy, null, null));
+    }
+}
@@ -0,0 +1,163 @@
+using Moq;
+using Opc.Ua;
+using Opc.Ua.Client;
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.OpcUaClient.Tests;
+
+/// <summary>#275 — the driver splits Read / Write calls to the server's declared OperationLimits.</summary>
+[Trait("Category", "Unit")]
+public sealed class OpcUaClientOperationLimitsTests
+{
+    [Theory]
+    [InlineData(0, 0u, new int[0])]                  // nothing to send => no call
+    [InlineData(5, 0u, new[] { 5 })]                 // 0 = unlimited
+    [InlineData(5, 5u, new[] { 5 })]                 // exactly fits
+    [InlineData(5, 100u, new[] { 5 })]               // limit larger than the batch
+    [InlineData(10, 4u, new[] { 4, 4, 2 })]          // remainder chunk
+    [InlineData(9, 3u, new[] { 3, 3, 3 })]
+    [InlineData(3, 1u, new[] { 1, 1, 1 })]
+    public void Chunk_splits_to_the_limit(int total, uint limit, int[] expectedSizes)
+    {
+        var chunks = OpcUaClientOperationLimits.Chunk(total, limit).ToList();
+
+        chunks.Select(c => c.Count).ToArray().ShouldBe(expectedSizes);
+        // Contiguous cover of [0, total): every item exactly once, in order.
+        var next = 0;
+        foreach (var (start, count) in chunks) { start.ShouldBe(next); next += count; }
+        next.ShouldBe(total);
+    }
+
+    [Fact]
+    public void FromValues_reads_good_uints_and_treats_bad_or_missing_as_unlimited()
+    {
+        var values = new List<DataValue>
+        {
+            new(new Variant(100u)),
+            new(new Variant(50u)),
+            new(StatusCodes.BadNodeIdUnknown),     // server doesn't publish MaxNodesPerBrowse
+            new(new Variant(7u)),
+        };
+
+        var limits = OpcUaClientOperationLimits.FromValues(values);
+
+        limits.MaxNodesPerRead.ShouldBe(100u);
+        limits.MaxNodesPerWrite.ShouldBe(50u);
+        limits.MaxNodesPerBrowse.ShouldBe(0u);
+        limits.MaxMonitoredItemsPerCall.ShouldBe(7u);
+        limits.MaxNodesPerHistoryReadData.ShouldBe(0u);   // short list => 0
+        limits.MaxNodesPerHistoryReadEvents.ShouldBe(0u);
+    }
+
+    private static (OpcUaClientDriver Drv, Mock<ISession> Session, List<int> ReadSizes, List<int> WriteSizes) Rig(
+        uint readLimit, uint writeLimit, int tagCount)
+    {
+        var tags = Enumerable.Range(0, tagCount)
+            .Select(i => new RawTagEntry($"raw/t{i}", $$"""{"nodeId":"ns=2;s=T{{i}}"}""", WriteIdempotent: false))
+            .ToList();
+        var options = new OpcUaClientDriverOptions { RawTags = tags };
+        var drv = new OpcUaClientDriver(options, "opcua-limits");
+        drv.SetNamespaceMapForTest(ZB.MOM.WW.OtOpcUa.Driver.OpcUaClient.NamespaceMap.FromTable(new NamespaceTable(), tags));
+        drv.SetOperationLimitsForTest(OpcUaClientOperationLimits.None with
+        {
+            MaxNodesPerRead = readLimit, MaxNodesPerWrite = writeLimit,
+        });
+
+        var readSizes = new List<int>();
+        var writeSizes = new List<int>();
+        var mock = new Mock<ISession>(MockBehavior.Loose);
+        mock.SetupGet(s => s.MessageContext)
+            .Returns(new ServiceMessageContext(SdkTelemetry.Context));
+        mock.SetupGet(s => s.NamespaceUris).Returns(new NamespaceTable());
+        mock.Setup(s => s.ReadAsync(It.IsAny<RequestHeader>(), It.IsAny<double>(), It.IsAny<TimestampsToReturn>(),
+                It.IsAny<ReadValueIdCollection>(), It.IsAny<CancellationToken>()))
+            .ReturnsAsync((RequestHeader _, double _, TimestampsToReturn _, ReadValueIdCollection nodes, CancellationToken _) =>
+            {
+                readSizes.Add(nodes.Count);
+                // Echo each node's identifier number back as the value so ordering across chunks is checkable.
+                var results = new DataValueCollection();
+                foreach (var n in nodes) results.Add(new DataValue(new Variant((string)n.NodeId.Identifier)));
+                return new ReadResponse { ResponseHeader = new ResponseHeader(), Results = results };
+            });
+        mock.Setup(s => s.WriteAsync(It.IsAny<RequestHeader>(), It.IsAny<WriteValueCollection>(), It.IsAny<CancellationToken>()))
+            .ReturnsAsync((RequestHeader _, WriteValueCollection nodes, CancellationToken _) =>
+            {
+                writeSizes.Add(nodes.Count);
+                var codes = new StatusCodeCollection();
+                foreach (var _ in nodes) codes.Add(StatusCodes.Good);
+                return new WriteResponse { ResponseHeader = new ResponseHeader(), Results = codes };
+            });
+        drv.SetSessionForTest(mock.Object);
+        return (drv, mock, readSizes, writeSizes);
+    }
+
+    [Fact]
+    public async Task ReadAsync_splits_to_MaxNodesPerRead_and_keeps_result_order()
+    {
+        var (drv, _, readSizes, _) = Rig(readLimit: 4, writeLimit: 0, tagCount: 10);
+        using var _ = drv;
+
+        var refs = Enumerable.Range(0, 10).Select(i => $"raw/t{i}").ToList();
+        var res = await drv.ReadAsync(refs, TestContext.Current.CancellationToken);
+
+        readSizes.ShouldBe([4, 4, 2]);
+        res.Count.ShouldBe(10);
+        for (var i = 0; i < 10; i++) res[i].Value.ShouldBe($"T{i}");   // positional mapping survives chunking
+        drv.GetHealth().State.ShouldBe(DriverState.Healthy);
+        drv.GetHealth().Diagnostics!["ChunkedRequestCount"].ShouldBe(1);
+    }
+
+    [Fact]
+    public async Task ReadAsync_with_no_declared_limit_sends_one_request()
+    {
+        var (drv, _, readSizes, _) = Rig(readLimit: 0, writeLimit: 0, tagCount: 10);
+        using var _ = drv;
+
+        await drv.ReadAsync(Enumerable.Range(0, 10).Select(i => $"raw/t{i}").ToList(), TestContext.Current.CancellationToken);
+
+        readSizes.ShouldBe([10]);
+    }
+
+    [Fact]
+    public async Task ReadAsync_a_failing_chunk_only_fails_its_own_tags()
+    {
+        var (drv, session, _, _) = Rig(readLimit: 2, writeLimit: 0, tagCount: 4);
+        using var _ = drv;
+        var call = 0;
+        session.Setup(s => s.ReadAsync(It.IsAny<RequestHeader>(), It.IsAny<double>(), It.IsAny<TimestampsToReturn>(),
+                It.IsAny<ReadValueIdCollection>(), It.IsAny<CancellationToken>()))
+            .Returns((RequestHeader _, double _, TimestampsToReturn _, ReadValueIdCollection nodes, CancellationToken _) =>
+            {
+                if (Interlocked.Increment(ref call) == 2) throw new ServiceResultException(StatusCodes.BadConnectionClosed);
+                var results = new DataValueCollection();
+                foreach (var n in nodes) results.Add(new DataValue(new Variant((string)n.NodeId.Identifier)));
+                return Task.FromResult(new ReadResponse { ResponseHeader = new ResponseHeader(), Results = results });
+            });
+
+        var res = await drv.ReadAsync(["raw/t0", "raw/t1", "raw/t2", "raw/t3"], TestContext.Current.CancellationToken);
+
+        res[0].Value.ShouldBe("T0");
+        res[1].Value.ShouldBe("T1");
+        res[2].StatusCode.ShouldBe(0x80050000u);   // BadCommunicationError, chunk 2 only
+        res[3].StatusCode.ShouldBe(0x80050000u);
+        drv.GetHealth().State.ShouldBe(DriverState.Degraded);
+        drv.GetHealth().Diagnostics!["ReadFailureCount"].ShouldBe(1);
+    }
+
+    [Fact]
+    public async Task WriteAsync_splits_to_MaxNodesPerWrite()
+    {
+        var (drv, _, _, writeSizes) = Rig(readLimit: 0, writeLimit: 3, tagCount: 7);
+        using var _ = drv;
+
+        var res = await drv.WriteAsync(
+            Enumerable.Range(0, 7).Select(i => new Core.Abstractions.WriteRequest($"raw/t{i}", i)).ToList(),
+            TestContext.Current.CancellationToken);
+
+        writeSizes.ShouldBe([3, 3, 1]);
+        res.Count.ShouldBe(7);
+        res.ShouldAllBe(r => r.StatusCode == 0u);
+    }
+}
@@ -0,0 +1,157 @@
+using Opc.Ua;
+using Shouldly;
+using Xunit;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.OpcUaClient.Tests;
+
+/// <summary>#273 subscription tuning, #277 revocation options, #278 discovery URL.</summary>
+[Trait("Category", "Unit")]
+public sealed class OpcUaClientTuningAndDiscoveryTests
+{
+    // ---- #273 ----
+
+    [Fact]
+    public void Defaults_equal_the_values_that_used_to_be_hardcoded()
+    {
+        var o = new OpcUaClientDriverOptions();
+
+        o.SubscriptionKeepAliveCount.ShouldBe(10u);
+        o.SubscriptionLifetimeCount.ShouldBe(1000u);
+        o.SubscriptionMaxNotificationsPerPublish.ShouldBe(0u);
+        o.SubscriptionPriority.ShouldBe((byte)0);
+        o.SubscriptionPublishingInterval.ShouldBeNull();
+        o.HonorServerOperationLimits.ShouldBeTrue();
+        o.DiscoveryUrl.ShouldBeNull();
+        o.CertificateValidation.RejectUnknownRevocationStatus.ShouldBeFalse();
+        o.CertificateValidation.IssuerStorePath.ShouldBeNull();
+        Should.NotThrow(() => OpcUaClientDriver.ValidateTuning(o));
+    }
+
+    [Fact]
+    public void Factory_json_binds_the_new_keys_and_old_json_keeps_defaults()
+    {
+        var o = OpcUaClientDriverFactoryExtensions.ParseOptions("d", """
+            {"subscriptionPublishingInterval":"00:00:02","subscriptionKeepAliveCount":20,
+             "subscriptionLifetimeCount":600,"subscriptionMaxNotificationsPerPublish":500,
+             "subscriptionPriority":9,"honorServerOperationLimits":false,
+             "discoveryUrl":"opc.tcp://lds:4840",
+             "certificateValidation":{"rejectUnknownRevocationStatus":true,"issuerStorePath":"/pki/issuers"}}
+            """);
+
+        o.SubscriptionPublishingInterval.ShouldBe(TimeSpan.FromSeconds(2));
+        o.SubscriptionKeepAliveCount.ShouldBe(20u);
+        o.SubscriptionLifetimeCount.ShouldBe(600u);
+        o.SubscriptionMaxNotificationsPerPublish.ShouldBe(500u);
+        o.SubscriptionPriority.ShouldBe((byte)9);
+        o.HonorServerOperationLimits.ShouldBeFalse();
+        o.DiscoveryUrl.ShouldBe("opc.tcp://lds:4840");
+        o.CertificateValidation.RejectUnknownRevocationStatus.ShouldBeTrue();
+        o.CertificateValidation.IssuerStorePath.ShouldBe("/pki/issuers");
+
+        var legacy = OpcUaClientDriverFactoryExtensions.ParseOptions("d", """{"endpointUrl":"opc.tcp://x:1"}""");
+        legacy.SubscriptionKeepAliveCount.ShouldBe(10u);
+        legacy.SubscriptionLifetimeCount.ShouldBe(1000u);
+    }
+
+    [Theory]
+    [InlineData(0u, 1000u)]     // keep-alive must be >= 1
+    [InlineData(10u, 29u)]      // lifetime < 3x keep-alive
+    [InlineData(500u, 1000u)]
+    public void ValidateTuning_rejects_out_of_range_counts(uint keepAlive, uint lifetime)
+    {
+        var o = new OpcUaClientDriverOptions { SubscriptionKeepAliveCount = keepAlive, SubscriptionLifetimeCount = lifetime };
+
+        Should.Throw<InvalidOperationException>(() => OpcUaClientDriver.ValidateTuning(o));
+    }
+
+    [Fact]
+    public void ValidateTuning_accepts_the_3x_boundary_and_rejects_bad_interval_or_discovery_url()
+    {
+        Should.NotThrow(() => OpcUaClientDriver.ValidateTuning(
+            new OpcUaClientDriverOptions { SubscriptionKeepAliveCount = 10, SubscriptionLifetimeCount = 30 }));
+        Should.Throw<InvalidOperationException>(() => OpcUaClientDriver.ValidateTuning(
+            new OpcUaClientDriverOptions { SubscriptionPublishingInterval = TimeSpan.Zero }));
+        Should.Throw<InvalidOperationException>(() => OpcUaClientDriver.ValidateTuning(
+            new OpcUaClientDriverOptions { DiscoveryUrl = "not a uri" }));
+    }
+
+    [Theory]
+    [InlineData(null, 1000, 1000)]     // no override: the per-call value
+    [InlineData(null, 10, 50)]         // floor still applies to the per-call value
+    [InlineData(2000, 250, 2000)]      // override wins over the per-call value
+    [InlineData(5, 250, 50)]           // ... and is floored too
+    public void ResolvePublishingIntervalMs_prefers_the_override_and_floors_at_50(int? overrideMs, int requestedMs, int expected)
+    {
+        var o = new OpcUaClientDriverOptions
+        {
+            SubscriptionPublishingInterval = overrideMs is { } ms ? TimeSpan.FromMilliseconds(ms) : null,
+        };
+
+        OpcUaClientDriver.ResolvePublishingIntervalMs(o, TimeSpan.FromMilliseconds(requestedMs)).ShouldBe(expected);
+    }
+
+    // ---- #277 ----
+
+    [Fact]
+    public void Revocation_failures_are_exactly_Revoked_and_IssuerRevoked()
+    {
+        OpcUaClientDriver.IsRevocationFailure(StatusCodes.BadCertificateRevoked).ShouldBeTrue();
+        OpcUaClientDriver.IsRevocationFailure(StatusCodes.BadCertificateIssuerRevoked).ShouldBeTrue();
+        // "unknown" is governed by RejectUnknownRevocationStatus, not auto-accept's hard exception;
+        // untrusted is what auto-accept exists to wave through.
+        OpcUaClientDriver.IsRevocationFailure(StatusCodes.BadCertificateRevocationUnknown).ShouldBeFalse();
+        OpcUaClientDriver.IsRevocationFailure(StatusCodes.BadCertificateUntrusted).ShouldBeFalse();
+        OpcUaClientDriver.IsRevocationFailure(StatusCodes.Good).ShouldBeFalse();
+    }
+
+    // ---- #278 ----
+
+    private static EndpointDescription Ep(string url, string policyUri, MessageSecurityMode mode) =>
+        new() { EndpointUrl = url, SecurityPolicyUri = policyUri, SecurityMode = mode };
+
+    [Fact]
+    public void ResolveEndpointCandidates_without_discovery_is_unchanged()
+    {
+        var o = new OpcUaClientDriverOptions { EndpointUrls = ["opc.tcp://a:1", "opc.tcp://b:2"] };
+
+        OpcUaClientDriver.ResolveEndpointCandidates(o, []).ShouldBe(["opc.tcp://a:1", "opc.tcp://b:2"]);
+        OpcUaClientDriver.ResolveEndpointCandidates(o).ShouldBe(["opc.tcp://a:1", "opc.tcp://b:2"]);
+    }
+
+    [Fact]
+    public void ResolveEndpointCandidates_prepends_discovered_urls_and_dedups_case_insensitively()
+    {
+        var o = new OpcUaClientDriverOptions { EndpointUrls = ["opc.tcp://Static:1", "opc.tcp://found:2"] };
+
+        var merged = OpcUaClientDriver.ResolveEndpointCandidates(o, ["opc.tcp://found:2", "opc.tcp://new:3"]);
+
+        merged.ShouldBe(["opc.tcp://found:2", "opc.tcp://new:3", "opc.tcp://Static:1"]);
+    }
+
+    [Fact]
+    public void ResolveEndpointCandidates_uses_the_single_EndpointUrl_after_discovered_when_no_list()
+    {
+        var o = new OpcUaClientDriverOptions { EndpointUrl = "opc.tcp://only:9" };
+
+        OpcUaClientDriver.ResolveEndpointCandidates(o, ["opc.tcp://d:1"]).ShouldBe(["opc.tcp://d:1", "opc.tcp://only:9"]);
+    }
+
+    [Fact]
+    public void FilterEndpointUrls_keeps_only_the_wanted_policy_and_mode()
+    {
+        const string b256 = "http://opcfoundation.org/UA/SecurityPolicy#Basic256Sha256";
+        const string none = "http://opcfoundation.org/UA/SecurityPolicy#None";
+        var endpoints = new[]
+        {
+            Ep("opc.tcp://h:1/none", none, MessageSecurityMode.None),
+            Ep("opc.tcp://h:1/sign", b256, MessageSecurityMode.Sign),
+            Ep("opc.tcp://h:1/enc", b256, MessageSecurityMode.SignAndEncrypt),
+            Ep("", b256, MessageSecurityMode.SignAndEncrypt),
+        };
+
+        OpcUaClientDriver.FilterEndpointUrls(endpoints, b256, MessageSecurityMode.SignAndEncrypt)
+            .ShouldBe(["opc.tcp://h:1/enc"]);
+        OpcUaClientDriver.FilterEndpointUrls(endpoints, none, MessageSecurityMode.None)
+            .ShouldBe(["opc.tcp://h:1/none"]);
+    }
+}
@@ -156,6 +156,50 @@ public sealed class OpcUaClientDriverPageFormSerializationTests
        result.ProbeTimeoutSeconds.ShouldBe(25);
    }

+    /// <summary>
+    ///     #273/#275/#277/#278: the typed form rewrites the whole record on save, so a key it does not model
+    ///     is silently dropped (#576). Every new option must survive FromRecord -> ToRecord.
+    /// </summary>
+    [Fact]
+    public void FormModel_RoundTrip_PreservesTuningLimitsRevocationAndDiscovery()
+    {
+        var original = new OpcUaClientDriverOptions
+        {
+            SubscriptionPublishingInterval = TimeSpan.FromMilliseconds(2500),
+            SubscriptionKeepAliveCount = 20,
+            SubscriptionLifetimeCount = 600,
+            SubscriptionMaxNotificationsPerPublish = 500,
+            SubscriptionPriority = 9,
+            HonorServerOperationLimits = false,
+            CertificateValidation = new OpcUaCertificateValidationOptions
+            {
+                RejectUnknownRevocationStatus = true,
+                IssuerStorePath = "/pki/issuers",
+            },
+            DiscoveryUrl = "opc.tcp://lds:4840",
+        };
+
+        var back = OpcUaClientDriverForm.OpcUaClientFormModel.FromRecord(original).ToRecord([]);
+
+        back.SubscriptionPublishingInterval.ShouldBe(TimeSpan.FromMilliseconds(2500));
+        back.SubscriptionKeepAliveCount.ShouldBe(20u);
+        back.SubscriptionLifetimeCount.ShouldBe(600u);
+        back.SubscriptionMaxNotificationsPerPublish.ShouldBe(500u);
+        back.SubscriptionPriority.ShouldBe((byte)9);
+        back.HonorServerOperationLimits.ShouldBeFalse();
+        back.CertificateValidation.RejectUnknownRevocationStatus.ShouldBeTrue();
+        back.CertificateValidation.IssuerStorePath.ShouldBe("/pki/issuers");
+        back.DiscoveryUrl.ShouldBe("opc.tcp://lds:4840");
+
+        // Defaults round-trip as defaults (blank override stays null, not 0 ms).
+        var def = OpcUaClientDriverForm.OpcUaClientFormModel.FromRecord(new OpcUaClientDriverOptions()).ToRecord([]);
+        def.SubscriptionPublishingInterval.ShouldBeNull();
+        def.SubscriptionKeepAliveCount.ShouldBe(10u);
+        def.SubscriptionLifetimeCount.ShouldBe(1000u);
+        def.HonorServerOperationLimits.ShouldBeTrue();
+        def.DiscoveryUrl.ShouldBeNull();
+    }
+
    [Fact]
    public void EndpointUrlRow_FromUrl_ToUrl_Trims()
    {