diff --git a/infra/lmxfakeproxy/tests/LmxFakeProxy.Tests/IntegrationSmokeTest.cs b/infra/lmxfakeproxy/tests/LmxFakeProxy.Tests/IntegrationSmokeTest.cs
new file mode 100644
index 0000000..4948cd2
--- /dev/null
+++ b/infra/lmxfakeproxy/tests/LmxFakeProxy.Tests/IntegrationSmokeTest.cs
@@ -0,0 +1,64 @@
+using ScadaLink.DataConnectionLayer.Adapters;
+
+namespace LmxFakeProxy.Tests;
+
+/// <summary>
+/// End-to-end smoke test connecting RealLmxProxyClient to LmxFakeProxy.
+/// Requires both OPC UA test server and LmxFakeProxy to be running.
+/// Run manually: dotnet test --filter "Category=Integration"
+/// </summary>
+[Trait("Category", "Integration")]
+public class IntegrationSmokeTest
+{
+    private const string Host = "localhost";
+    private const int Port = 50051;
+
+    [Fact]
+    public async Task ConnectReadWriteSubscribe_EndToEnd()
+    {
+        var factory = new RealLmxProxyClientFactory();
+        var client = factory.Create(Host, Port, null);
+
+        try
+        {
+            // Connect
+            await client.ConnectAsync();
+            Assert.True(client.IsConnected);
+
+            // Read initial value
+            var vtq = await client.ReadAsync("Motor.Speed");
+            Assert.Equal(LmxQuality.Good, vtq.Quality);
+
+            // Write a value
+            await client.WriteAsync("Motor.Speed", 42.5);
+
+            // Read back
+            var vtq2 = await client.ReadAsync("Motor.Speed");
+            Assert.Equal(42.5, (double)vtq2.Value!);
+
+            // ReadBatch
+            var batch = await client.ReadBatchAsync(new[] { "Motor.Speed", "Pump.FlowRate" });
+            Assert.Equal(2, batch.Count);
+
+            // Subscribe briefly
+            LmxVtq? lastUpdate = null;
+            var sub = await client.SubscribeAsync(
+                new[] { "Motor.Speed" },
+                (tag, v) => lastUpdate = v);
+
+            // Write to trigger subscription update
+            await client.WriteAsync("Motor.Speed", 99.0);
+            await Task.Delay(2000);
+
+            await sub.DisposeAsync();
+            Assert.NotNull(lastUpdate);
+
+            // Disconnect
+            await client.DisconnectAsync();
+        }
+        finally
+        {
+            await client.DisposeAsync();
+        }
+    }
+}
diff --git a/infra/lmxfakeproxy/tests/LmxFakeProxy.Tests/LmxFakeProxy.Tests.csproj b/infra/lmxfakeproxy/tests/LmxFakeProxy.Tests/LmxFakeProxy.Tests.csproj
index a17b68a..398e4f0 100644
--- a/infra/lmxfakeproxy/tests/LmxFakeProxy.Tests/LmxFakeProxy.Tests.csproj
+++ b/infra/lmxfakeproxy/tests/LmxFakeProxy.Tests/LmxFakeProxy.Tests.csproj
@@ -17,5 +17,6 @@
 
   <ItemGroup>
     <ProjectReference Include="../../LmxFakeProxy.csproj" />
+    <ProjectReference Include="../../../../src/ScadaLink.DataConnectionLayer/ScadaLink.DataConnectionLayer.csproj" />
   </ItemGroup>
 </Project>