diff --git a/src/ZB.MOM.WW.MxGateway.Server/Security/Authorization/ConstraintEnforcer.cs b/src/ZB.MOM.WW.MxGateway.Server/Security/Authorization/ConstraintEnforcer.cs
index 031e4b3..abdd70d 100644
--- a/src/ZB.MOM.WW.MxGateway.Server/Security/Authorization/ConstraintEnforcer.cs
+++ b/src/ZB.MOM.WW.MxGateway.Server/Security/Authorization/ConstraintEnforcer.cs
@@ -121,8 +121,10 @@ public sealed class ConstraintEnforcer(
     /// <param name="target">The target being accessed (tag address or handle).</param>
     /// <param name="failure">The constraint failure details.</param>
     /// <param name="correlationId">
-    ///     The per-request client correlation id, if any. Persisted as the audit record's
-    ///     <c>CorrelationId</c> when it parses as a GUID; a non-GUID value is dropped (left null).
+    ///     The per-request client correlation id, if any. Persisted as the audit record's typed
+    ///     <c>CorrelationId</c> when it parses as a GUID; a non-GUID value leaves that column null.
+    ///     The raw string is always preserved in <c>DetailsJson["clientCorrelationId"]</c> so a
+    ///     non-GUID id (e.g. from Rust/Python/Java clients) is never silently lost.
     /// </param>
     /// <param name="cancellationToken">Token to observe for cancellation.</param>
     public async Task RecordDenialAsync(
@@ -153,6 +155,11 @@ public sealed class ConstraintEnforcer(
                 ["message"] = failure.Message,
                 ["commandKind"] = commandKind,
                 ["target"] = target,
+                // Always preserve the raw client correlation id here so it is never silently
+                // lost: the typed CorrelationId column only retains GUID-parseable ids, but
+                // clients (Rust/Python/Java) commonly send non-GUID or empty trace ids. The
+                // raw id is a client trace id, not a secret, so storing it is fine.
+                ["clientCorrelationId"] = correlationId ?? "",
             }),
         };
 
diff --git a/src/ZB.MOM.WW.MxGateway.Tests/Gateway/Grpc/MxAccessGatewayServiceConstraintTests.cs b/src/ZB.MOM.WW.MxGateway.Tests/Gateway/Grpc/MxAccessGatewayServiceConstraintTests.cs
index a01cfb8..9d226f7 100644
--- a/src/ZB.MOM.WW.MxGateway.Tests/Gateway/Grpc/MxAccessGatewayServiceConstraintTests.cs
+++ b/src/ZB.MOM.WW.MxGateway.Tests/Gateway/Grpc/MxAccessGatewayServiceConstraintTests.cs
@@ -548,6 +548,33 @@ public sealed class MxAccessGatewayServiceConstraintTests
         Assert.Equal("42", enforcer.RecordedDenials[0].Target);
     }
 
+    /// <summary>
+    ///     End-to-end wiring (M-2): the per-request <c>ClientCorrelationId</c> must propagate
+    ///     all the way through <c>Invoke</c> -> <c>ApplyConstraintsAsync</c> -> the unary write
+    ///     enforce helper -> <c>RecordDenialAsync</c>, so the recorded denial carries the exact
+    ///     id the client sent (including non-GUID trace ids used by Rust/Python/Java clients).
+    /// </summary>
+    [Fact]
+    public async Task Invoke_Write_WithDeniedHandle_ThreadsClientCorrelationIdIntoRecordedDenial()
+    {
+        const string CorrelationId = "rust-client-Write-7";
+        PredicateConstraintEnforcer enforcer = new()
+        {
+            DenyWriteHandle = (serverHandle, itemHandle) => serverHandle == 7 && itemHandle == 42,
+        };
+        FakeSessionManager sessionManager = CreateSessionManagerWithSeed();
+        MxAccessGatewayService service = CreateService(sessionManager, enforcer);
+
+        MxCommandRequest request = CreateWriteRequest(serverHandle: 7, itemHandle: 42);
+        request.ClientCorrelationId = CorrelationId;
+
+        await Assert.ThrowsAsync<RpcException>(
+            async () => await service.Invoke(request, new TestServerCallContext()));
+
+        Assert.Single(enforcer.RecordedDenials);
+        Assert.Equal(CorrelationId, enforcer.RecordedDenials[0].CorrelationId);
+    }
+
     /// <summary>
     ///     Unary <c>WriteSecured</c> against a denied handle takes the same enforce path
     ///     and rejects identically — proving the four-arm switch in
diff --git a/src/ZB.MOM.WW.MxGateway.Tests/Security/Authorization/ConstraintEnforcerTests.cs b/src/ZB.MOM.WW.MxGateway.Tests/Security/Authorization/ConstraintEnforcerTests.cs
index 627b01a..19a7917 100644
--- a/src/ZB.MOM.WW.MxGateway.Tests/Security/Authorization/ConstraintEnforcerTests.cs
+++ b/src/ZB.MOM.WW.MxGateway.Tests/Security/Authorization/ConstraintEnforcerTests.cs
@@ -1,3 +1,4 @@
+using System.Text.Json;
 using ZB.MOM.WW.Audit;
 using ZB.MOM.WW.MxGateway.Contracts.Proto.Galaxy;
 using ZB.MOM.WW.MxGateway.Contracts.Proto;
@@ -102,9 +103,12 @@ public sealed class ConstraintEnforcerTests
         Assert.Equal(correlationId, auditEvent.CorrelationId);
     }
 
-    /// <summary>A denial with a non-GUID correlation id leaves the audit correlation id null.</summary>
+    /// <summary>
+    ///     A denial with a non-GUID correlation id leaves the typed audit correlation id null but
+    ///     still preserves the raw client correlation id in DetailsJson so it is not lost.
+    /// </summary>
     [Fact]
-    public async Task RecordDenialAsync_WithNonGuidCorrelationId_LeavesCorrelationIdNull()
+    public async Task RecordDenialAsync_WithNonGuidCorrelationId_LeavesCorrelationIdNullButPreservesRawInDetails()
     {
         ConstraintEnforcer enforcer = CreateEnforcer(out FakeAuditWriter auditWriter);
 
@@ -113,11 +117,17 @@ public sealed class ConstraintEnforcerTests
             "Read",
             "Secret.Tag",
             new ConstraintFailure("read_scope", "Tag is outside the API key read scope."),
-            "cli-xyz",
+            "rust-client-Write-7",
             CancellationToken.None);
 
         AuditEvent auditEvent = Assert.Single(auditWriter.Events);
         Assert.Null(auditEvent.CorrelationId);
+        Assert.NotNull(auditEvent.DetailsJson);
+
+        Dictionary<string, string>? details =
+            JsonSerializer.Deserialize<Dictionary<string, string>>(auditEvent.DetailsJson);
+        Assert.NotNull(details);
+        Assert.Equal("rust-client-Write-7", details["clientCorrelationId"]);
     }
 
     /// <summary>A denial with no identity records the canonical "anonymous" actor.</summary>