Wire SDK for remote-TCP end to end; live-verify RemoteTcpIntegrated

Executes docs/plans/tcp-connection-validation.md. Full read-only SDK
surface now works against a remote AVEVA Historian over Net.TCP with
Windows transport authentication. 124/124 tests pass; the +10 new live
integration tests in RemoteTcpIntegrationTests.cs are gated by
HISTORIAN_REMOTE_TCP_HOST + HISTORIAN_REMOTE_TCP_TAG.

Two SDK bugs found while executing the plan:

1. Historian2020ProtocolDialect.ReadRawAsync / ReadAggregateAsync /
   ReadAtTimeAsync / ReadEventsAsync had explicit
   `if (_options.Transport != HistorianTransport.LocalPipe) return Missing<T>`
   guards. These were a guardrail from before the orchestrators handled
   TCP; the orchestrators have always used CreateBindingPair(options)
   which dispatches on transport correctly. Gates removed.

2. HistorianWcfStatusClient and HistorianWcfEventOrchestrator hardcoded
   HistorianWcfBindingFactory.CreatePipeEndpointAddress for the auxiliary
   services (Stat, Trx, Retr). Worked for LocalPipe; for TCP it produced
   an EndpointAddress with scheme net.pipe attached to a TCP binding
   (channel factory rejected the URI). Worse, when only the endpoint was
   transport-aware, the binding still requested a Windows-transport-
   security upgrade that the Stat endpoint over TCP doesn't support
   (auxiliaries don't repeat the auth — the Hist session is already
   authenticated). Added two helpers:
   - HistorianWcfBindingFactory.CreateAuxiliaryEndpointAddress(options, name)
     -> net.pipe for LocalPipe, net.tcp for remote
   - HistorianWcfBindingFactory.CreateAuxiliaryBinding(options)
     -> NamedPipe for LocalPipe, plain MdasNetTcpBinding for remote
   Both call sites updated.

Live verification against the remote (probed previously in prior
sessions; reachability re-confirmed today):
- ProbeAsync over RemoteTcpIntegrated and RemoteTcpCertificate
- ReadRawAsync (8 samples returned for SysTimeSec)
- ReadAggregateAsync (TimeWeightedAverage, 1-min cycle, 10-min window)
- ReadAtTimeAsync (3 timestamps)
- BrowseTagNamesAsync (finds the test tag)
- GetTagMetadataAsync (full metadata populated)
- ReadEventsAsync (chain runs without throwing)
- GetConnectionStatusAsync (ConnectedToServer=true)
- GetSystemParameterAsync (HistorianVersion="20,0,000,000")

The default 'NT SERVICE\aahClientAccessPoint' SPN turned out to work
for the remote too — discovery workstream A (SPN-finding) was not
needed in practice.

README and the TCP plan doc updated to reflect the executed status.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

README.md

@@ -46,8 +46,10 @@ await foreach (HistorianSample sample in client.ReadRawAsync(
 ```
 
 For a remote Historian over Net.TCP set `Transport = HistorianTransport.RemoteTcpIntegrated`
-and `Host` to the server hostname. Remote-TCP plumbing exists but only `LocalPipe`
+and `Host` to the server hostname. Both `RemoteTcpIntegrated` (Windows transport
-has live verification in this checkout.
+auth) and `RemoteTcpCertificate` (server-cert TLS) are now live-verified for
+`ProbeAsync`; `RemoteTcpIntegrated` is additionally live-verified for the full
+read / browse / metadata / event / status surface.
 
 ## Build & test
 
@@ -158,6 +160,9 @@ property dictionary → Retr.EndEventQuery → Hist.Close2
 
 ## Status
 
-108 unit + live integration tests pass (`dotnet test --logger "console;verbosity=minimal"`).
+124 unit + live integration tests pass (`dotnet test --logger "console;verbosity=minimal"`).
-Full read-only SDK surface verified end-to-end against a local Historian. Remote-TCP
+Full read-only SDK surface verified end-to-end against both a local Historian
-transports and explicit-credentials path are wired but await live verification.
+(`LocalPipe`) and a remote Historian (`RemoteTcpIntegrated` over Net.TCP with
+Windows transport auth). `RemoteTcpCertificate` ProbeAsync is live-verified;
+the other ops over the certificate transport plus the explicit-credentials
+path await live verification.

docs/plans/tcp-connection-validation.md

@@ -1,9 +1,29 @@
 # TCP Connection Validation Plan
 
-Status: PLAN ONLY (no implementation yet). Scope is **live verification of
+Status: **EXECUTED on 2026-05-04**. RemoteTcpIntegrated transport is now
-the existing remote-TCP transport plumbing**, not new wire-protocol
+live-verified end-to-end against `10.100.0.48` (Historian InterfaceVersion=11)
-reverse-engineering — the wire format itself is the same MDAS-encoded SOAP
+for ProbeAsync, ReadRawAsync, ReadAggregateAsync, ReadAtTimeAsync,
-already verified end-to-end over `LocalPipe`.
+ReadEventsAsync, BrowseTagNamesAsync, GetTagMetadataAsync,
+GetConnectionStatusAsync, GetSystemParameterAsync. RemoteTcpCertificate
+verified for ProbeAsync only (full surface awaits a non-current-user
+credential probe). Test count 114 → 124 (+10) per success criteria.
+
+Two SDK bugs were uncovered and fixed during execution:
+1. `Historian2020ProtocolDialect` had explicit `if (Transport != LocalPipe)
+   return Missing` gates on Read/Aggregate/AtTime/ReadEvents that were a
+   leftover guardrail from before the orchestrators handled TCP. Removed —
+   the orchestrators already used `CreateBindingPair(options)` correctly.
+2. `HistorianWcfStatusClient` and `HistorianWcfEventOrchestrator` hardcoded
+   `CreatePipeEndpointAddress` for auxiliary services (Stat, Trx, Retr).
+   Added `HistorianWcfBindingFactory.CreateAuxiliaryEndpointAddress` and
+   `CreateAuxiliaryBinding` helpers that dispatch on `Transport`; for TCP
+   the auxiliaries use plain `MdasNetTcpBinding` (no transport upgrade —
+   the Hist endpoint already authenticated the session).
+
+Original scope is **live verification of the existing remote-TCP transport
+plumbing**, not new wire-protocol reverse-engineering — the wire format
+itself is the same MDAS-encoded SOAP already verified end-to-end over
+`LocalPipe`.
 
 Read together with:
 

src/AVEVA.Historian.Client/Protocol/Historian2020ProtocolDialect.cs

@@ -15,14 +15,9 @@ internal sealed class Historian2020ProtocolDialect
 
     public IAsyncEnumerable<HistorianSample> ReadRawAsync(string tag, DateTime startUtc, DateTime endUtc, int maxValues, CancellationToken cancellationToken)
     {
-        if (_options.Transport != HistorianTransport.LocalPipe)
-        {
-            return Missing<HistorianSample>($"StartDataRetrievalQuery/Full over {_options.Transport}", cancellationToken);
-        }
-
         if (!RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
         {
-            return Missing<HistorianSample>("StartDataRetrievalQuery/Full requires Windows for the LocalPipe + SSPI path", cancellationToken);
+            return Missing<HistorianSample>("StartDataRetrievalQuery/Full requires Windows for the SSPI path", cancellationToken);
         }
 
         return ReadRawWindowsAsync(tag, startUtc, endUtc, maxValues, cancellationToken);
@@ -38,14 +33,9 @@ internal sealed class Historian2020ProtocolDialect
 
     public IAsyncEnumerable<HistorianAggregateSample> ReadAggregateAsync(string tag, DateTime startUtc, DateTime endUtc, RetrievalMode mode, TimeSpan interval, CancellationToken cancellationToken)
     {
-        if (_options.Transport != HistorianTransport.LocalPipe)
-        {
-            return Missing<HistorianAggregateSample>($"StartDataRetrievalQuery/{mode} over {_options.Transport}", cancellationToken);
-        }
-
         if (!RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
         {
-            return Missing<HistorianAggregateSample>($"StartDataRetrievalQuery/{mode} requires Windows for the LocalPipe + SSPI path", cancellationToken);
+            return Missing<HistorianAggregateSample>($"StartDataRetrievalQuery/{mode} requires Windows for the SSPI path", cancellationToken);
         }
 
         return ReadAggregateWindowsAsync(tag, startUtc, endUtc, mode, interval, cancellationToken);
@@ -63,14 +53,9 @@ internal sealed class Historian2020ProtocolDialect
     {
         cancellationToken.ThrowIfCancellationRequested();
 
-        if (_options.Transport != HistorianTransport.LocalPipe)
-        {
-            throw new ProtocolEvidenceMissingException($"StartDataRetrievalQuery/Interpolated at-time over {_options.Transport}");
-        }
-
         if (!RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
         {
-            throw new ProtocolEvidenceMissingException("StartDataRetrievalQuery/Interpolated at-time requires Windows for the LocalPipe + SSPI path");
+            throw new ProtocolEvidenceMissingException("StartDataRetrievalQuery/Interpolated at-time requires Windows for the SSPI path");
         }
 
 #pragma warning disable CA1416
@@ -86,14 +71,9 @@ internal sealed class Historian2020ProtocolDialect
 
     public IAsyncEnumerable<HistorianEvent> ReadEventsAsync(DateTime startUtc, DateTime endUtc, CancellationToken cancellationToken)
     {
-        if (_options.Transport != HistorianTransport.LocalPipe)
-        {
-            return Missing<HistorianEvent>($"StartEventDataRetrievalQuery over {_options.Transport}", cancellationToken);
-        }
-
         if (!RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
         {
-            return Missing<HistorianEvent>("StartEventDataRetrievalQuery requires Windows for the LocalPipe + SSPI path", cancellationToken);
+            return Missing<HistorianEvent>("StartEventDataRetrievalQuery requires Windows for the SSPI path", cancellationToken);
         }
 
         return ReadEventsWindowsAsync(startUtc, endUtc, cancellationToken);

src/AVEVA.Historian.Client/Wcf/HistorianWcfBindingFactory.cs

@@ -164,4 +164,42 @@ internal static class HistorianWcfBindingFactory
 
         return new EndpointAddress($"net.pipe://{host}/{serviceName}");
     }
+
+    /// <summary>
+    /// Returns the appropriate endpoint address for an auxiliary service (Stat, Trx, etc.)
+    /// based on the transport — net.pipe for LocalPipe, net.tcp for the remote variants.
+    /// Use this rather than <see cref="CreatePipeEndpointAddress"/> directly when the calling
+    /// code may run under any transport.
+    /// </summary>
+    public static EndpointAddress CreateAuxiliaryEndpointAddress(HistorianClientOptions options, string serviceName)
+    {
+        ArgumentNullException.ThrowIfNull(options);
+        ArgumentException.ThrowIfNullOrWhiteSpace(serviceName);
+
+        return options.Transport == HistorianTransport.LocalPipe
+            ? CreatePipeEndpointAddress(options.Host, serviceName)
+            : CreateEndpointAddress(options.Host, options.Port, serviceName);
+    }
+
+    /// <summary>
+    /// Returns the appropriate binding for an auxiliary service (Stat, Trx, etc.) given the
+    /// transport. For LocalPipe, same NamedPipe binding as History. For remote TCP variants,
+    /// plain <see cref="CreateMdasNetTcpBinding"/> — auxiliaries don't repeat the Windows-
+    /// transport-security upgrade that the History service negotiates; the established session
+    /// authenticates the client already.
+    /// </summary>
+    [SupportedOSPlatform("windows")]
+    public static Binding CreateAuxiliaryBinding(HistorianClientOptions options)
+    {
+        ArgumentNullException.ThrowIfNull(options);
+
+        TimeSpan timeout = options.RequestTimeout;
+        return options.Transport switch
+        {
+            HistorianTransport.LocalPipe => CreateMdasNetNamedPipeBinding(timeout),
+            HistorianTransport.RemoteTcpIntegrated => CreateMdasNetTcpBinding(timeout),
+            HistorianTransport.RemoteTcpCertificate => CreateMdasNetTcpBinding(timeout),
+            _ => throw new NotSupportedException($"Transport {options.Transport} is not supported.")
+        };
+    }
 }

src/AVEVA.Historian.Client/Wcf/HistorianWcfEventOrchestrator.cs

@@ -92,13 +92,14 @@ internal sealed class HistorianWcfEventOrchestrator
     {
         Guid contextKey = Guid.NewGuid();
         var (histBinding, histEndpoint, retrBinding, retrEndpoint) = HistorianWcfBindingFactory.CreateBindingPair(_options);
-        EndpointAddress statusEndpoint = HistorianWcfBindingFactory.CreatePipeEndpointAddress(_options.Host, HistorianWcfServiceNames.Status);
+        Binding auxBinding = HistorianWcfBindingFactory.CreateAuxiliaryBinding(_options);
-        EndpointAddress transactionEndpoint = HistorianWcfBindingFactory.CreatePipeEndpointAddress(_options.Host, HistorianWcfServiceNames.Transaction);
+        EndpointAddress statusEndpoint = HistorianWcfBindingFactory.CreateAuxiliaryEndpointAddress(_options, HistorianWcfServiceNames.Status);
+        EndpointAddress transactionEndpoint = HistorianWcfBindingFactory.CreateAuxiliaryEndpointAddress(_options, HistorianWcfServiceNames.Transaction);
         uint clientHandle = HistorianWcfAuthChainHelper.OpenAuthenticatedConnection(
             _options, histBinding, histEndpoint, contextKey, cancellationToken,
             connectionMode: HistorianWcfAuthChainHelper.NativeIntegratedReadOnlyConnectionMode,
             additionalSetup: (historyChannel, context) =>
-                AddCmEventTagViaAddT(historyChannel, context, histBinding, statusEndpoint, transactionEndpoint, retrBinding, retrEndpoint));
+                AddCmEventTagViaAddT(historyChannel, context, auxBinding, statusEndpoint, transactionEndpoint, retrBinding, retrEndpoint));
         return RunEventQuery(retrBinding, retrEndpoint, clientHandle, startUtc, endUtc, cancellationToken);
     }
 

src/AVEVA.Historian.Client/Wcf/HistorianWcfStatusClient.cs

@@ -36,12 +36,13 @@ internal static class HistorianWcfStatusClient
     {
         Guid contextKey = Guid.NewGuid();
         var (histBinding, histEndpoint, _, _) = HistorianWcfBindingFactory.CreateBindingPair(options);
-        EndpointAddress statusEndpoint = HistorianWcfBindingFactory.CreatePipeEndpointAddress(options.Host, HistorianWcfServiceNames.Status);
+        Binding statusBinding = HistorianWcfBindingFactory.CreateAuxiliaryBinding(options);
+        EndpointAddress statusEndpoint = HistorianWcfBindingFactory.CreateAuxiliaryEndpointAddress(options, HistorianWcfServiceNames.Status);
 
         string? value = null;
         HistorianWcfAuthChainHelper.OpenAuthenticatedConnection(
             options, histBinding, histEndpoint, contextKey, CancellationToken.None,
-            additionalSetup: (_, context) => value = QuerySystemParameter(histBinding, statusEndpoint, context.ClientHandle, parameterName));
+            additionalSetup: (_, context) => value = QuerySystemParameter(statusBinding, statusEndpoint, context.ClientHandle, parameterName));
         return value;
     }
 

tests/AVEVA.Historian.Client.Tests/RemoteTcpIntegrationTests.cs

@@ -0,0 +1,233 @@
+using System.Runtime.Versioning;
+using AVEVA.Historian.Client.Models;
+using Xunit.Abstractions;
+
+namespace AVEVA.Historian.Client.Tests;
+
+/// <remarks>
+/// Live verification of the RemoteTcpIntegrated and RemoteTcpCertificate transports
+/// per <c>docs/plans/tcp-connection-validation.md</c>. Gated by env vars:
+/// <list type="bullet">
+///   <item><c>HISTORIAN_REMOTE_TCP_HOST</c> — hostname or IP of a reachable remote Historian.</item>
+///   <item><c>HISTORIAN_REMOTE_TCP_TAG</c> — tag with non-zero history rows.</item>
+///   <item><c>HISTORIAN_REMOTE_TCP_SPN</c> — optional Kerberos SPN override (default per <c>HistorianClientOptions.TargetSpn</c>).</item>
+///   <item><c>HISTORIAN_REMOTE_TCPCERT_HOST</c> + <c>HISTORIAN_REMOTE_TCPCERT_DNS</c> — for the certificate transport variant.</item>
+/// </list>
+/// All tests skip cleanly if the gating env var isn't set.
+/// </remarks>
+[SupportedOSPlatform("windows")]
+public sealed class RemoteTcpIntegrationTests
+{
+    private readonly ITestOutputHelper _output;
+
+    public RemoteTcpIntegrationTests(ITestOutputHelper output)
+    {
+        _output = output;
+    }
+
+    [Fact]
+    public async Task ProbeAsync_RemoteTcpIntegrated_ReturnsTrue()
+    {
+        string? host = Environment.GetEnvironmentVariable("HISTORIAN_REMOTE_TCP_HOST");
+        if (string.IsNullOrWhiteSpace(host) || !OperatingSystem.IsWindows())
+        {
+            return;
+        }
+
+        HistorianClient client = new(BuildIntegratedOptions(host));
+        bool reachable = await client.ProbeAsync(CancellationToken.None);
+        Assert.True(reachable, "ProbeAsync against remote-TCP host returned false");
+    }
+
+    [Fact]
+    public async Task ReadRawAsync_RemoteTcpIntegrated_ReturnsAtLeastOneRow()
+    {
+        string? host = Environment.GetEnvironmentVariable("HISTORIAN_REMOTE_TCP_HOST");
+        string? testTag = Environment.GetEnvironmentVariable("HISTORIAN_REMOTE_TCP_TAG");
+        if (string.IsNullOrWhiteSpace(host) || string.IsNullOrWhiteSpace(testTag) || !OperatingSystem.IsWindows())
+        {
+            return;
+        }
+
+        HistorianClient client = new(BuildIntegratedOptions(host));
+        DateTime endUtc = DateTime.UtcNow;
+        DateTime startUtc = endUtc - TimeSpan.FromDays(7);
+
+        List<HistorianSample> samples = [];
+        await foreach (HistorianSample sample in client.ReadRawAsync(testTag, startUtc, endUtc, maxValues: 8, CancellationToken.None))
+        {
+            samples.Add(sample);
+        }
+
+        _output.WriteLine($"Returned {samples.Count} samples for {testTag}");
+        Assert.NotEmpty(samples);
+        Assert.All(samples, s => Assert.Equal(testTag, s.TagName));
+    }
+
+    [Fact]
+    public async Task GetTagMetadataAsync_RemoteTcpIntegrated_PopulatesFields()
+    {
+        string? host = Environment.GetEnvironmentVariable("HISTORIAN_REMOTE_TCP_HOST");
+        string? testTag = Environment.GetEnvironmentVariable("HISTORIAN_REMOTE_TCP_TAG");
+        if (string.IsNullOrWhiteSpace(host) || string.IsNullOrWhiteSpace(testTag) || !OperatingSystem.IsWindows())
+        {
+            return;
+        }
+
+        HistorianClient client = new(BuildIntegratedOptions(host));
+        HistorianTagMetadata? metadata = await client.GetTagMetadataAsync(testTag, CancellationToken.None);
+        Assert.NotNull(metadata);
+        Assert.Equal(testTag, metadata.Name);
+    }
+
+    [Fact]
+    public async Task GetSystemParameterAsync_RemoteTcpIntegrated_ReturnsHistorianVersion()
+    {
+        string? host = Environment.GetEnvironmentVariable("HISTORIAN_REMOTE_TCP_HOST");
+        if (string.IsNullOrWhiteSpace(host) || !OperatingSystem.IsWindows())
+        {
+            return;
+        }
+
+        HistorianClient client = new(BuildIntegratedOptions(host));
+        string? value = await client.GetSystemParameterAsync("HistorianVersion", CancellationToken.None);
+        _output.WriteLine($"HistorianVersion: {value}");
+        Assert.False(string.IsNullOrWhiteSpace(value));
+    }
+
+    [Fact]
+    public async Task ReadAggregateAsync_RemoteTcpIntegrated_ReturnsTimeWeightedRows()
+    {
+        string? host = Environment.GetEnvironmentVariable("HISTORIAN_REMOTE_TCP_HOST");
+        string? testTag = Environment.GetEnvironmentVariable("HISTORIAN_REMOTE_TCP_TAG");
+        if (string.IsNullOrWhiteSpace(host) || string.IsNullOrWhiteSpace(testTag) || !OperatingSystem.IsWindows())
+        {
+            return;
+        }
+
+        HistorianClient client = new(BuildIntegratedOptions(host));
+        DateTime endUtc = DateTime.UtcNow;
+        DateTime startUtc = endUtc - TimeSpan.FromMinutes(10);
+
+        List<HistorianAggregateSample> samples = [];
+        await foreach (HistorianAggregateSample sample in client.ReadAggregateAsync(
+            testTag, startUtc, endUtc, RetrievalMode.TimeWeightedAverage, TimeSpan.FromMinutes(1), CancellationToken.None))
+        {
+            samples.Add(sample);
+        }
+
+        Assert.NotEmpty(samples);
+        Assert.All(samples, s => Assert.Equal(testTag, s.TagName));
+    }
+
+    [Fact]
+    public async Task ReadAtTimeAsync_RemoteTcpIntegrated_ReturnsTimestamps()
+    {
+        string? host = Environment.GetEnvironmentVariable("HISTORIAN_REMOTE_TCP_HOST");
+        string? testTag = Environment.GetEnvironmentVariable("HISTORIAN_REMOTE_TCP_TAG");
+        if (string.IsNullOrWhiteSpace(host) || string.IsNullOrWhiteSpace(testTag) || !OperatingSystem.IsWindows())
+        {
+            return;
+        }
+
+        HistorianClient client = new(BuildIntegratedOptions(host));
+        DateTime now = DateTime.UtcNow;
+        DateTime[] timestamps = [now - TimeSpan.FromMinutes(5), now - TimeSpan.FromMinutes(2), now - TimeSpan.FromMinutes(1)];
+        IReadOnlyList<HistorianSample> samples = await client.ReadAtTimeAsync(testTag, timestamps, CancellationToken.None);
+        Assert.NotEmpty(samples);
+        Assert.All(samples, s => Assert.Equal(testTag, s.TagName));
+    }
+
+    [Fact]
+    public async Task BrowseTagNamesAsync_RemoteTcpIntegrated_FindsTestTag()
+    {
+        string? host = Environment.GetEnvironmentVariable("HISTORIAN_REMOTE_TCP_HOST");
+        string? testTag = Environment.GetEnvironmentVariable("HISTORIAN_REMOTE_TCP_TAG");
+        if (string.IsNullOrWhiteSpace(host) || string.IsNullOrWhiteSpace(testTag) || !OperatingSystem.IsWindows())
+        {
+            return;
+        }
+
+        HistorianClient client = new(BuildIntegratedOptions(host));
+        List<string> names = [];
+        await foreach (string name in client.BrowseTagNamesAsync(testTag, CancellationToken.None))
+        {
+            names.Add(name);
+        }
+        Assert.Contains(testTag, names);
+    }
+
+    [Fact]
+    public async Task ReadEventsAsync_RemoteTcpIntegrated_DoesNotThrow()
+    {
+        string? host = Environment.GetEnvironmentVariable("HISTORIAN_REMOTE_TCP_HOST");
+        if (string.IsNullOrWhiteSpace(host) || !OperatingSystem.IsWindows())
+        {
+            return;
+        }
+
+        HistorianClient client = new(BuildIntegratedOptions(host));
+        DateTime endUtc = DateTime.UtcNow;
+        DateTime startUtc = endUtc - TimeSpan.FromDays(1);
+
+        // Empty result is acceptable — we're just verifying the chain doesn't throw over TCP.
+        List<HistorianEvent> events = [];
+        await foreach (HistorianEvent evt in client.ReadEventsAsync(startUtc, endUtc, CancellationToken.None))
+        {
+            events.Add(evt);
+        }
+        Assert.NotNull(events);
+    }
+
+    [Fact]
+    public async Task GetConnectionStatusAsync_RemoteTcpIntegrated_ReportsConnectedToServer()
+    {
+        string? host = Environment.GetEnvironmentVariable("HISTORIAN_REMOTE_TCP_HOST");
+        if (string.IsNullOrWhiteSpace(host) || !OperatingSystem.IsWindows())
+        {
+            return;
+        }
+
+        HistorianClient client = new(BuildIntegratedOptions(host));
+        HistorianConnectionStatus status = await client.GetConnectionStatusAsync(CancellationToken.None);
+        Assert.True(status.ConnectedToServer);
+        Assert.False(status.ErrorOccurred);
+        Assert.Equal(host, status.ServerName);
+    }
+
+    [Fact]
+    public async Task ProbeAsync_RemoteTcpCertificate_ReturnsTrue()
+    {
+        string? host = Environment.GetEnvironmentVariable("HISTORIAN_REMOTE_TCPCERT_HOST");
+        if (string.IsNullOrWhiteSpace(host) || !OperatingSystem.IsWindows())
+        {
+            return;
+        }
+
+        HistorianClient client = new(new HistorianClientOptions
+        {
+            Host = host,
+            Port = HistorianClientOptions.DefaultPort,
+            IntegratedSecurity = false,
+            Transport = HistorianTransport.RemoteTcpCertificate,
+        });
+
+        bool reachable = await client.ProbeAsync(CancellationToken.None);
+        Assert.True(reachable, "ProbeAsync over RemoteTcpCertificate returned false");
+    }
+
+    private static HistorianClientOptions BuildIntegratedOptions(string host)
+    {
+        string? spn = Environment.GetEnvironmentVariable("HISTORIAN_REMOTE_TCP_SPN");
+        return new HistorianClientOptions
+        {
+            Host = host,
+            Port = HistorianClientOptions.DefaultPort,
+            IntegratedSecurity = true,
+            Transport = HistorianTransport.RemoteTcpIntegrated,
+            // SPN default in HistorianClientOptions is "NT SERVICE\aahClientAccessPoint" which is the
+            // LocalPipe service identity; for remote TCP, override via env var if needed.
+            TargetSpn = string.IsNullOrWhiteSpace(spn) ? "NT SERVICE\\aahClientAccessPoint" : spn,
+        };
+    }
+}