diff --git a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Calculation/CalculationDriverProbe.cs b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Calculation/CalculationDriverProbe.cs
index 060cf5bd..0a34b959 100644
--- a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Calculation/CalculationDriverProbe.cs
+++ b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Calculation/CalculationDriverProbe.cs
@@ -13,10 +13,16 @@ namespace ZB.MOM.WW.OtOpcUa.Driver.Calculation;
 /// </summary>
 public sealed class CalculationDriverProbe : IDriverProbe
 {
+    // Mirrors CalculationDriverFactoryExtensions.JsonOptions / CalculationDriver.ReinitJsonOptions
+    // (AllowTrailingCommas + ReadCommentHandling included) so a config blob the real spawn/reinit path
+    // tolerates never fails Test-Connect as "invalid JSON" — the probe must never be STRICTER than the
+    // path it is standing in for.
     private static readonly JsonSerializerOptions Opts = new()
     {
         PropertyNameCaseInsensitive = true,
         UnmappedMemberHandling = JsonUnmappedMemberHandling.Skip,
+        ReadCommentHandling = JsonCommentHandling.Skip,
+        AllowTrailingCommas = true,
         Converters = { new JsonStringEnumConverter() },
     };
 
diff --git a/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Calculation.Tests/CalculationDriverProbeTests.cs b/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Calculation.Tests/CalculationDriverProbeTests.cs
new file mode 100644
index 00000000..5d1be8f4
--- /dev/null
+++ b/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Calculation.Tests/CalculationDriverProbeTests.cs
@@ -0,0 +1,72 @@
+using Shouldly;
+using Xunit;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.Calculation.Tests;
+
+/// <summary>
+///     Unit tests for <see cref="CalculationDriverProbe"/> — the Calculation pseudo-driver's Test-Connect
+///     probe (parse-only, since there is no backend to reach).
+/// </summary>
+public sealed class CalculationDriverProbeTests
+{
+    private static readonly CalculationDriverProbe Sut = new();
+
+    [Fact]
+    public async Task Empty_config_json_fails()
+    {
+        var result = await Sut.ProbeAsync("", TimeSpan.FromSeconds(1), TestContext.Current.CancellationToken);
+        result.Ok.ShouldBeFalse();
+        result.Message.ShouldNotBeNullOrWhiteSpace();
+    }
+
+    [Fact]
+    public async Task Malformed_json_fails()
+    {
+        var result = await Sut.ProbeAsync("not json", TimeSpan.FromSeconds(1), TestContext.Current.CancellationToken);
+        result.Ok.ShouldBeFalse();
+        result.Message.ShouldNotBeNullOrWhiteSpace();
+    }
+
+    [Fact]
+    public async Task A_config_with_no_rawTags_array_is_still_valid()
+    {
+        var result = await Sut.ProbeAsync("{}", TimeSpan.FromSeconds(1), TestContext.Current.CancellationToken);
+        result.Ok.ShouldBeTrue(result.Message);
+    }
+
+    [Fact]
+    public async Task A_well_formed_rawTags_config_is_valid()
+    {
+        const string json = """{"rawTags":[{"rawPath":"calc/e/x","tagConfig":"{}","writeIdempotent":false}]}""";
+        var result = await Sut.ProbeAsync(json, TimeSpan.FromSeconds(1), TestContext.Current.CancellationToken);
+        result.Ok.ShouldBeTrue(result.Message);
+    }
+
+    /// <summary>
+    ///     The probe must not be STRICTER than the real spawn/reinit path: both
+    ///     <c>CalculationDriverFactoryExtensions.JsonOptions</c> and <c>CalculationDriver.ReinitJsonOptions</c>
+    ///     set <c>AllowTrailingCommas</c> + <c>ReadCommentHandling.Skip</c>. Before this pin the probe's own
+    ///     options omitted both, so a config a real deploy would accept could fail Test-Connect as "invalid".
+    /// </summary>
+    [Fact]
+    public async Task Tolerates_trailing_commas_like_the_real_spawn_and_reinit_paths()
+    {
+        const string json = """{"rawTags":[{"rawPath":"calc/e/x","tagConfig":"{}","writeIdempotent":false},],}""";
+        var result = await Sut.ProbeAsync(json, TimeSpan.FromSeconds(1), TestContext.Current.CancellationToken);
+        result.Ok.ShouldBeTrue(result.Message);
+    }
+
+    /// <summary>Same parity claim for comments, which the spawn/reinit path also tolerates.</summary>
+    [Fact]
+    public async Task Tolerates_comments_like_the_real_spawn_and_reinit_paths()
+    {
+        const string json = """
+            {
+                // a hand-edited config comment
+                "rawTags": []
+            }
+            """;
+        var result = await Sut.ProbeAsync(json, TimeSpan.FromSeconds(1), TestContext.Current.CancellationToken);
+        result.Ok.ShouldBeTrue(result.Message);
+    }
+}