diff --git a/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Heidenhain.Tests/HeidenhainLiveIntegrationTests.cs b/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Heidenhain.Tests/HeidenhainLiveIntegrationTests.cs
index b0a9c4522..020425a31 100644
--- a/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Heidenhain.Tests/HeidenhainLiveIntegrationTests.cs
+++ b/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Heidenhain.Tests/HeidenhainLiveIntegrationTests.cs
@@ -85,4 +85,38 @@ public sealed class HeidenhainLiveIntegrationTests
             TestContext.Current.SendDiagnosticMessage($"{tags[i].RawPath} = {values[i].Value} (0x{values[i].StatusCode:X8})");
         values[0].StatusCode.ShouldBe(HeidenhainStatus.Good);
     }
+
+    /// <summary>#867: integer tool leaves must reach clients with their declared runtime type, not Double.</summary>
+    [Fact]
+    public async Task Real_control_tool_leaves_keep_integer_types()
+    {
+        Assert.SkipWhen(string.IsNullOrWhiteSpace(Host), "HEIDENHAIN_LSV2_HOST not set — real-controller gate skipped.");
+        var ct = TestContext.Current.CancellationToken;
+        var tags = new[] { TestTags.Raw("Tool/Number"), TestTags.Raw("Tool/Index"), TestTags.Raw("Tool/AxisCode") };
+        var options = new HeidenhainDriverOptions
+        {
+            Devices = [new HeidenhainDeviceOptions { Host = Host!, Port = Port, DeviceName = "dev1" }],
+            RawTags = tags,
+            Access = new HeidenhainAccessOptions { InspectPassword = Environment.GetEnvironmentVariable("OTOPCUA_HEIDENHAIN_INSPECT_PASSWORD") is { Length: > 0 } ? "env:OTOPCUA_HEIDENHAIN_INSPECT_PASSWORD" : null },
+        };
+        await using var driver = new HeidenhainDriver(options, "live");
+        await driver.InitializeAsync("{}", ct);
+        await driver.SubscribeAsync(tags.Select(t => t.RawPath).ToList(), TimeSpan.FromSeconds(1), ct);
+        var deadline = DateTime.UtcNow.AddSeconds(30);
+        IReadOnlyList<Core.Abstractions.DataValueSnapshot> values;
+        do
+        {
+            await Task.Delay(500, ct);
+            values = await driver.ReadAsync(tags.Select(t => t.RawPath).ToList(), ct);
+        } while (values.Any(v => v.StatusCode != HeidenhainStatus.Good) && DateTime.UtcNow < deadline);
+
+        var expected = new[] { typeof(long), typeof(int), typeof(int) };
+        for (var i = 0; i < tags.Length; i++)
+        {
+            TestContext.Current.SendDiagnosticMessage($"{tags[i].RawPath} = {values[i].Value} ({values[i].Value?.GetType().Name}) (0x{values[i].StatusCode:X8})");
+            if (values[i].StatusCode == HeidenhainStatus.Good)
+                values[i].Value!.GetType().ShouldBe(expected[i]);
+        }
+        values.Count(v => v.StatusCode == HeidenhainStatus.Good).ShouldBeGreaterThan(0);
+    }
 }