diff --git a/src/ZB.MOM.WW.MxGateway.Worker.Tests/MxAccess/MxAccessCommandExecutorTests.cs b/src/ZB.MOM.WW.MxGateway.Worker.Tests/MxAccess/MxAccessCommandExecutorTests.cs
index 2b4b0aa..16e53c9 100644
--- a/src/ZB.MOM.WW.MxGateway.Worker.Tests/MxAccess/MxAccessCommandExecutorTests.cs
+++ b/src/ZB.MOM.WW.MxGateway.Worker.Tests/MxAccess/MxAccessCommandExecutorTests.cs
@@ -897,6 +897,9 @@ public sealed class MxAccessCommandExecutorTests
         FakeMxAccessComObjectFactory factory = new(fakeComObject);
         using StaRuntime runtime = CreateRuntime();
         using MxAccessStaSession session = new(runtime, factory, new NoopEventSink());
+        // No completion source in this test — disable the bounded reply wait
+        // so the forwarding assertions don't pay the default 1.5 s timeout.
+        session.WriteCompletionTimeout = TimeSpan.Zero;
         await session.StartAsync(workerProcessId: 1234);
 
         MxCommandReply reply = await session.DispatchAsync(CreateWriteSecuredCommand(
@@ -919,6 +922,8 @@ public sealed class MxAccessCommandExecutorTests
         FakeMxAccessComObjectFactory factory = new(fakeComObject);
         using StaRuntime runtime = CreateRuntime();
         using MxAccessStaSession session = new(runtime, factory, new NoopEventSink());
+        // Same rationale as the WriteSecured forwarding test above.
+        session.WriteCompletionTimeout = TimeSpan.Zero;
         await session.StartAsync(workerProcessId: 1234);
         DateTime timestamp = new(2026, 5, 19, 13, 30, 0, DateTimeKind.Utc);
 
@@ -934,6 +939,181 @@ public sealed class MxAccessCommandExecutorTests
         Assert.Equal(44, fakeComObject.WriteVerifierUserId);
     }
 
+    /// <summary>
+    ///     Verifies the fast-completion ordering edge: a completion recorded while
+    ///     the WriteSecured COM call is still on the stack (MXAccess committing
+    ///     synchronously) is newer than the pre-call baseline and lands on the
+    ///     reply — the wait never misses a callback that beat it.
+    /// </summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
+    [Fact]
+    public async Task DispatchAsync_WriteSecured_WhenCompletionArrivesDuringComCall_ReturnsStatuses()
+    {
+        FakeMxAccessComObject fakeComObject = new(registerHandle: 82);
+        FakeMxAccessComObjectFactory factory = new(fakeComObject);
+        CompletionCacheEventSink sink = new();
+        fakeComObject.OnWriteSecuredCallback = () =>
+            sink.WriteCompletionCache.Record(82, 820, CreateCompletionRows(detail: 4321));
+        using StaRuntime runtime = CreateRuntime();
+        using MxAccessStaSession session = new(runtime, factory, sink);
+        await session.StartAsync(workerProcessId: 1234);
+
+        MxCommandReply reply = await session.DispatchAsync(CreateWriteSecuredCommand(
+            "write-secured-fast", serverHandle: 82, itemHandle: 820, value: 1, currentUserId: 11, verifierUserId: 22));
+
+        Assert.Equal(ProtocolStatusCode.Ok, reply.ProtocolStatus.Code);
+        Assert.True(reply.HasHresult);
+        Assert.Equal(0, reply.Hresult);
+        MxStatusProxy row = Assert.Single(reply.Statuses);
+        Assert.Equal(4321, row.Detail);
+        Assert.Equal(MxStatusCategory.Ok, row.Category);
+    }
+
+    /// <summary>
+    ///     Verifies the pump-wait path: the completion arrives after the COM call
+    ///     returned, while the executor is pump-waiting, and still lands on the
+    ///     reply.
+    /// </summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
+    [Fact]
+    public async Task DispatchAsync_WriteSecured_WhenCompletionArrivesWhileWaiting_ReturnsStatuses()
+    {
+        FakeMxAccessComObject fakeComObject = new(registerHandle: 83);
+        FakeMxAccessComObjectFactory factory = new(fakeComObject);
+        CompletionCacheEventSink sink = new();
+        using StaRuntime runtime = CreateRuntime();
+        using MxAccessStaSession session = new(runtime, factory, sink);
+        session.WriteCompletionTimeout = TimeSpan.FromSeconds(10);
+        await session.StartAsync(workerProcessId: 1234);
+
+        Task<MxCommandReply> pending = session.DispatchAsync(CreateWriteSecuredCommand(
+            "write-secured-waiting", serverHandle: 83, itemHandle: 830, value: 1, currentUserId: 11, verifierUserId: 22));
+        await Task.Delay(50);
+        sink.WriteCompletionCache.Record(83, 830, CreateCompletionRows(detail: 99));
+
+        MxCommandReply reply = await pending;
+
+        Assert.Equal(ProtocolStatusCode.Ok, reply.ProtocolStatus.Code);
+        Assert.Equal(99, Assert.Single(reply.Statuses).Detail);
+    }
+
+    /// <summary>
+    ///     Verifies the timeout fallback: no completion within the bounded wait
+    ///     returns today's reply shape — protocol OK with EMPTY statuses (the
+    ///     consumer's honest-unconfirmed path), never a synthesized failure row.
+    /// </summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
+    [Fact]
+    public async Task DispatchAsync_WriteSecured_WhenNoCompletion_TimesOutWithEmptyStatusesAndOkProtocol()
+    {
+        FakeMxAccessComObject fakeComObject = new(registerHandle: 84);
+        FakeMxAccessComObjectFactory factory = new(fakeComObject);
+        CompletionCacheEventSink sink = new();
+        using StaRuntime runtime = CreateRuntime();
+        using MxAccessStaSession session = new(runtime, factory, sink);
+        session.WriteCompletionTimeout = TimeSpan.FromMilliseconds(100);
+        await session.StartAsync(workerProcessId: 1234);
+
+        MxCommandReply reply = await session.DispatchAsync(CreateWriteSecuredCommand(
+            "write-secured-timeout", serverHandle: 84, itemHandle: 840, value: 1, currentUserId: 11, verifierUserId: 22));
+
+        Assert.Equal(ProtocolStatusCode.Ok, reply.ProtocolStatus.Code);
+        Assert.True(reply.HasHresult);
+        Assert.Equal(0, reply.Hresult);
+        Assert.Empty(reply.Statuses);
+    }
+
+    /// <summary>
+    ///     Verifies the version-baseline rule end to end: a completion recorded
+    ///     BEFORE the write was dispatched is stale and must not be misattributed
+    ///     to this write — the reply times out empty instead.
+    /// </summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
+    [Fact]
+    public async Task DispatchAsync_WriteSecured_IgnoresStaleCompletionFromBeforeTheCall()
+    {
+        FakeMxAccessComObject fakeComObject = new(registerHandle: 85);
+        FakeMxAccessComObjectFactory factory = new(fakeComObject);
+        CompletionCacheEventSink sink = new();
+        sink.WriteCompletionCache.Record(85, 850, CreateCompletionRows(detail: 1111));
+        using StaRuntime runtime = CreateRuntime();
+        using MxAccessStaSession session = new(runtime, factory, sink);
+        session.WriteCompletionTimeout = TimeSpan.FromMilliseconds(100);
+        await session.StartAsync(workerProcessId: 1234);
+
+        MxCommandReply reply = await session.DispatchAsync(CreateWriteSecuredCommand(
+            "write-secured-stale", serverHandle: 85, itemHandle: 850, value: 1, currentUserId: 11, verifierUserId: 22));
+
+        Assert.Equal(ProtocolStatusCode.Ok, reply.ProtocolStatus.Code);
+        Assert.Empty(reply.Statuses);
+    }
+
+    /// <summary>
+    ///     Verifies that WriteSecured2 correlates the same way as WriteSecured
+    ///     (fast-completion edge).
+    /// </summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
+    [Fact]
+    public async Task DispatchAsync_WriteSecured2_WhenCompletionArrivesDuringComCall_ReturnsStatuses()
+    {
+        FakeMxAccessComObject fakeComObject = new(registerHandle: 86);
+        FakeMxAccessComObjectFactory factory = new(fakeComObject);
+        CompletionCacheEventSink sink = new();
+        fakeComObject.OnWriteSecuredCallback = () =>
+            sink.WriteCompletionCache.Record(86, 860, CreateCompletionRows(detail: 2222));
+        using StaRuntime runtime = CreateRuntime();
+        using MxAccessStaSession session = new(runtime, factory, sink);
+        await session.StartAsync(workerProcessId: 1234);
+
+        MxCommandReply reply = await session.DispatchAsync(CreateWriteSecured2Command(
+            "write-secured2-fast", serverHandle: 86, itemHandle: 860, value: 1,
+            timestamp: new DateTime(2026, 8, 9, 12, 0, 0, DateTimeKind.Utc), currentUserId: 33, verifierUserId: 44));
+
+        Assert.Equal(ProtocolStatusCode.Ok, reply.ProtocolStatus.Code);
+        Assert.Equal(2222, Assert.Single(reply.Statuses).Detail);
+    }
+
+    /// <summary>
+    ///     Verifies plain Write stays fire-and-forget: even with a huge completion
+    ///     timeout configured and no completion source, the reply returns
+    ///     immediately (guarded well under the configured wait) with empty
+    ///     statuses — only the secured write kinds enter the bounded wait.
+    /// </summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
+    [Fact]
+    public async Task DispatchAsync_Write_DoesNotWaitForCompletion()
+    {
+        FakeMxAccessComObject fakeComObject = new(registerHandle: 87);
+        FakeMxAccessComObjectFactory factory = new(fakeComObject);
+        CompletionCacheEventSink sink = new();
+        using StaRuntime runtime = CreateRuntime();
+        using MxAccessStaSession session = new(runtime, factory, sink);
+        session.WriteCompletionTimeout = TimeSpan.FromSeconds(30);
+        await session.StartAsync(workerProcessId: 1234);
+
+        Task<MxCommandReply> pending = session.DispatchAsync(CreateWriteCommand(
+            "plain-write-no-wait", serverHandle: 87, itemHandle: 870, value: 1, userId: 5));
+        Task completed = await Task.WhenAny(pending, Task.Delay(TimeSpan.FromSeconds(5)));
+
+        Assert.Same(pending, completed);
+        MxCommandReply reply = await pending;
+        Assert.Equal(ProtocolStatusCode.Ok, reply.ProtocolStatus.Code);
+        Assert.Empty(reply.Statuses);
+    }
+
+    private static Google.Protobuf.Collections.RepeatedField<MxStatusProxy> CreateCompletionRows(int detail)
+    {
+        return new Google.Protobuf.Collections.RepeatedField<MxStatusProxy>
+        {
+            new MxStatusProxy
+            {
+                Success = 1,
+                Category = MxStatusCategory.Ok,
+                Detail = detail,
+            },
+        };
+    }
+
     /// <summary>Verifies that Write without a payload returns an invalid request error.</summary>
     /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
@@ -1775,6 +1955,28 @@ public sealed class MxAccessCommandExecutorTests
             TimeSpan.FromMilliseconds(25));
     }
 
+    /// <summary>
+    ///     Test sink that owns a real write-completion cache without touching the
+    ///     MXAccess COM RCW (Attach is a no-op). Implements the provider seam so
+    ///     <see cref="MxAccessSession.Create"/> shares this cache with the write
+    ///     executor, letting tests record completions the executor's bounded
+    ///     wait then observes.
+    /// </summary>
+    private sealed class CompletionCacheEventSink : IMxAccessEventSink, IWriteCompletionCacheProvider
+    {
+        public MxAccessWriteCompletionCache WriteCompletionCache { get; } = new MxAccessWriteCompletionCache();
+
+        public void Attach(
+            object mxAccessComObject,
+            string sessionId)
+        {
+        }
+
+        public void Detach()
+        {
+        }
+    }
+
     private sealed class FakeMxAccessComObject : IMxAccessServer
     {
         private readonly int registerHandle;
@@ -1790,6 +1992,14 @@ public sealed class MxAccessCommandExecutorTests
         private readonly IReadOnlyDictionary<int, Exception> writeExceptionByItemHandle;
         private readonly List<string> operationNames = new();
 
+        /// <summary>
+        ///     Invoked at the end of a successful WriteSecured/WriteSecured2 —
+        ///     stands in for MXAccess committing synchronously and delivering
+        ///     OnWriteComplete while the COM call is still on the stack, so
+        ///     tests can exercise the fast-completion ordering edge.
+        /// </summary>
+        public Action? OnWriteSecuredCallback { get; set; }
+
         /// <summary>Initializes a fake MXAccess COM object with the given handles and optional exceptions.</summary>
         /// <param name="registerHandle">Return value for Register method.</param>
         /// <param name="addItemHandle">Return value for AddItem method.</param>
@@ -2100,6 +2310,7 @@ public sealed class MxAccessCommandExecutorTests
             WriteValue = value;
             WriteThreadId = Environment.CurrentManagedThreadId;
             ThrowIfWriteFailureConfigured(itemHandle);
+            OnWriteSecuredCallback?.Invoke();
         }
 
         /// <inheritdoc />
@@ -2120,6 +2331,7 @@ public sealed class MxAccessCommandExecutorTests
             WriteTimestamp = timestamp;
             WriteThreadId = Environment.CurrentManagedThreadId;
             ThrowIfWriteFailureConfigured(itemHandle);
+            OnWriteSecuredCallback?.Invoke();
         }
 
         private void ThrowIfWriteFailureConfigured(int itemHandle)