Merge remote-tracking branch 'origin/main' into agent-1/issue-16-implement-blazor-server-dashboard

Issue #19: gateway end-to-end smoke with fake worker

docs/GatewayTesting.md

@@ -0,0 +1,58 @@
+# Gateway Testing
+
+Gateway tests run without installed MXAccess by using fake workers, fake
+transports, and in-process gRPC service fakes. Live MXAccess verification belongs
+in opt-in integration tests because it depends on installed COM components and
+provider state.
+
+## Fake Worker Harness
+
+`FakeWorkerHarness` in `src/MxGateway.Tests/Gateway/Workers/Fakes/` provides an
+in-process worker side for named-pipe IPC tests. It uses the same
+`WorkerFrameReader`, `WorkerFrameWriter`, and `WorkerEnvelope` contract as the
+gateway so tests exercise real frame validation and worker-client state changes.
+
+Use the harness when a gateway or session test needs worker behavior without
+starting `MxGateway.Worker.exe` or loading MXAccess COM. The harness scripts:
+
+- `WorkerHello` and `WorkerReady` startup,
+- command replies with matching correlation ids,
+- ordered `WorkerEvent` frames,
+- `WorkerFault` frames,
+- shutdown acknowledgements,
+- malformed protobuf payloads and oversized frame headers,
+- slow or hung workers by withholding a reply.
+
+Session-level tests can connect the harness to the pipe created by
+`SessionWorkerClientFactory` with `ConnectToGatewayPipeAsync`. Lower-level
+`WorkerClient` tests can use `CreateConnectedPairAsync` to create both pipe ends
+inside the test.
+
+`GatewayEndToEndFakeWorkerSmokeTests` composes the real gRPC service,
+`SessionManager`, `SessionWorkerClientFactory`, `WorkerClient`, and
+`EventStreamService` with a scripted fake worker launcher. The smoke test covers
+`OpenSession`, `Register`, `AddItem`, `Advise`, one streamed `OnDataChange`
+event, and `CloseSession` without loading MXAccess COM.
+
+## Focused Commands
+
+Run the fake worker tests after changing gateway worker IPC, session startup, or
+event streaming behavior:
+
+```bash
+dotnet test src/MxGateway.Tests/MxGateway.Tests.csproj --filter FullyQualifiedName~FakeWorkerHarnessTests
+dotnet test src/MxGateway.Tests/MxGateway.Tests.csproj --filter FullyQualifiedName~SessionWorkerClientFactoryFakeWorkerTests
+dotnet test src/MxGateway.Tests/MxGateway.Tests.csproj --filter FullyQualifiedName~GatewayEndToEndFakeWorkerSmokeTests
+```
+
+Run the gateway test project after shared gateway test infrastructure changes:
+
+```bash
+dotnet test src/MxGateway.Tests/MxGateway.Tests.csproj
+```
+
+## Related Documentation
+
+- [Gateway Process Design](./gateway-process-design.md)
+- [Worker Frame Protocol](./WorkerFrameProtocol.md)
+- [MXAccess Worker Instance Detailed Design](./mxaccess-worker-instance-design.md)

docs/gateway-dashboard-design.md

@@ -34,9 +34,13 @@ SignalR circuit. Bootstrap is sufficient for a basic dashboard.
 
 ## Hosting Model
 
-The dashboard is hosted by `MxGateway.Server` alongside the gRPC API.
+The dashboard is hosted by `MxGateway.Server` alongside the gRPC API. When
+`MxGateway:Dashboard:Enabled` is `true`, `MapGatewayDashboard()` maps the
+configured `Dashboard:PathBase` to the Blazor Server app and maps the login,
+logout, and access-denied HTTP endpoints beside it. When dashboard hosting is
+disabled, those routes are not mapped.
 
-Suggested endpoint layout:
+Endpoint layout:
 
 ```text
 /dashboard
@@ -45,7 +49,7 @@ Suggested endpoint layout:
 /dashboard/workers
 /dashboard/events
 /dashboard/settings
-/_blazor
+/dashboard/_blazor
 ```
 
 The app should redirect `/` to `/dashboard` only if the deployment wants the
@@ -59,9 +63,10 @@ MxGateway.Server
     Components/
       App.razor
       Routes.razor
+      DashboardPageBase.cs
+      DashboardDisplay.cs
       Layout/
         DashboardLayout.razor
-        NavMenu.razor
       Pages/
         DashboardHome.razor
         SessionsPage.razor
@@ -69,26 +74,21 @@ MxGateway.Server
         WorkersPage.razor
         EventsPage.razor
         SettingsPage.razor
-      Components/
+      Shared/
         MetricCard.razor
-        SessionTable.razor
-        WorkerTable.razor
-        EventRatePanel.razor
+        StatusBadge.razor
         FaultList.razor
-    Services/
-      DashboardSnapshotService.cs
-      DashboardUpdateHub.cs
-      DashboardAuthorization.cs
-    Models/
-      DashboardSnapshot.cs
-      SessionSummary.cs
-      WorkerSummary.cs
-      MetricSummary.cs
+    DashboardSnapshotService.cs
+    DashboardAuthorizationHandler.cs
+    DashboardAuthenticator.cs
+    DashboardSnapshot.cs
+    DashboardSessionSummary.cs
+    DashboardWorkerSummary.cs
+    DashboardMetricSummary.cs
 ```
 
-`DashboardUpdateHub` here means an internal application update service, not a
-separate public SignalR hub unless implementation proves one is needed. Blazor
-Server already uses SignalR for UI circuits.
+Blazor Server provides the SignalR circuit for UI updates. The implementation
+does not add a separate public dashboard hub.
 
 ## Dashboard Data Source
 
@@ -137,7 +137,7 @@ gateway internals.
 
 Use Blazor Server component state updates for real-time dashboard refresh.
 
-Recommended pattern:
+Implemented pattern:
 
 1. Page/component subscribes to `WatchSnapshotsAsync`.
 2. Snapshot service emits updates from a bounded channel or timer.
@@ -147,10 +147,8 @@ Recommended pattern:
 
 Default update cadence:
 
-- immediate update on session create/close/fault,
-- immediate update on worker fault,
 - periodic metrics refresh every 1 second,
-- event-rate windows updated every 1 second.
+- event counters update on the next snapshot tick.
 
 Avoid pushing every MXAccess data-change event to the dashboard. Aggregate event
 counts and rates instead.
@@ -257,19 +255,18 @@ Do not show API key secrets or pepper values.
 
 ## Authentication And Authorization
 
-Dashboard access should use the same API-key authentication model as gRPC where
+Dashboard access uses the same API-key authentication model as gRPC where
 practical.
 
-Recommended v1 behavior:
+Implemented v1 behavior:
 
-- dashboard disabled by default unless configured,
 - when enabled, require API key auth,
 - require `admin` scope for dashboard access,
-- accept API key through a secure cookie established by a simple login form, or
-  through reverse-proxy/header configuration for local deployments,
-- do not put API keys in query strings.
+- accept API key through a secure cookie established by a simple login form,
+- do not put API keys in query strings,
+- validate anti-forgery tokens for login and logout posts.
 
-Simplest implementation path:
+The implementation path is:
 
 1. Add `/dashboard/login`.
 2. User submits API key over HTTPS.
@@ -281,6 +278,13 @@ Simplest implementation path:
 For local development, allow an explicit `Dashboard:AllowAnonymousLocalhost`
 option. It must default to false.
 
+`DashboardAuthenticator` keeps API-key validation outside UI components. It
+formats the submitted key as a bearer authorization header for
+`IApiKeyVerifier`, rejects non-admin keys when `Dashboard:RequireAdminScope` is
+enabled, and creates the dashboard cookie principal without storing raw API key
+material. `DashboardAuthorizationHandler` enforces the cookie, admin-scope, and
+explicit loopback bypass decisions for all protected dashboard routes.
+
 ## Configuration
 
 Suggested configuration:
@@ -314,7 +318,9 @@ Suggested configuration:
 
 ## Styling
 
-Use Bootstrap utility classes and a small local stylesheet.
+The dashboard serves Bootstrap 5.3.3 assets from
+`src/MxGateway.Server/wwwroot/lib/bootstrap/` and local layout/status styling
+from `src/MxGateway.Server/wwwroot/css/dashboard.css`.
 
 Recommended visual language:
 
@@ -355,15 +361,18 @@ Integration tests should verify:
 
 ## Initial Implementation Slice
 
-The first dashboard slice should implement:
+The first dashboard slice implements:
 
 1. Blazor Server hosting in `MxGateway.Server`.
-2. Bootstrap static assets.
+2. local Bootstrap static assets.
 3. dashboard configuration binding.
 4. dashboard auth using API key login and HTTP-only cookie.
 5. read-only `DashboardSnapshotService`.
 6. home page with metric cards.
-7. sessions page with active session table.
+7. sessions page with active session table and session details.
 8. workers page with worker table.
-9. 1-second realtime refresh through Blazor Server.
-10. redaction tests for secrets.
+9. events page with aggregate counters.
+10. settings page with redacted effective configuration.
+11. periodic realtime refresh through Blazor Server.
+12. route-mapping tests, disabled-dashboard tests, auth tests, and snapshot
+    projection/redaction tests.

docs/gateway-process-design.md

@@ -206,13 +206,23 @@ accounting and a clear fan-out policy.
 Behavior:
 
 1. Validate session id and authorize event access.
-2. Attach a stream cursor to the session event channel.
-3. Send events in worker sequence order.
-4. Stop on client cancellation, session close, or session fault.
-5. Emit a terminal status when the session faults if gRPC status alone cannot
+2. Attach the single active subscriber lease for the session.
+3. Read worker events into a bounded public stream queue.
+4. Send events in worker sequence order.
+5. Stop on client cancellation, session close, or session fault.
+6. Emit a terminal status when the session faults if gRPC status alone cannot
    preserve the required details.
 
-The gateway must not reorder events from one worker.
+`EventStreamService` owns subscriber tracking and public stream backpressure.
+The default policy allows one active subscriber per session. A second subscriber
+is rejected with `EventSubscriberAlreadyActive`. Stream cancellation releases
+the subscriber lease so a later stream can attach to the session.
+
+The gateway must not reorder events from one worker. `EventStreamService` writes
+mapped events to a bounded first-in, first-out queue and faults the session with
+`EventQueueOverflow` if the queue fills. The gateway does not synthesize
+`OperationComplete`; it forwards that family only when the worker reports a
+native MXAccess `OperationComplete` event.
 
 ## Web Dashboard
 
@@ -584,7 +594,8 @@ worker MXAccess event
   -> worker outbound event queue
   -> worker pipe writer
   -> gateway read loop
-  -> session event channel
+  -> worker client event queue
+  -> EventStreamService bounded stream queue
   -> gRPC StreamEvents
 ```
 
@@ -598,13 +609,15 @@ The gateway should record:
 
 Default backpressure policy for parity testing should be fail-fast:
 
-1. If the session event channel fills, fault the session.
+1. If the worker client event queue fills, fault the worker client.
+2. If the public stream queue fills, fault the gateway session.
 2. Preserve the overflow details in logs and metrics.
 3. Do not silently drop data-change events.
 
-Do not set a production event-rate target before measurement. Emit event rate,
-queue depth, stream send latency, and overflow metrics. Later production modes
-may support explicit coalescing by item handle as an opt-in behavior.
+Do not set a production event-rate target before measurement. `GatewayMetrics`
+records received event counts by family, queue depth, stream disconnects, and
+overflow counts. Later production modes may support explicit coalescing by item
+handle as an opt-in behavior.
 
 The gateway should not synthesize `OperationComplete` from write completion,
 command replies, ASB completion queues, or completion-only status frames. Forward
@@ -650,6 +663,16 @@ server-streaming calls and stores the authenticated `ApiKeyIdentity` in
 `Authentication:Mode` set to `Disabled` bypasses API-key verification for local
 development only.
 
+Dashboard authentication reuses the API-key verifier and scope model. The
+dashboard login endpoint accepts the key in a form post, checks `admin` scope
+when `Dashboard:RequireAdminScope` is enabled, and signs in with the
+`MxGateway.Dashboard` cookie scheme. The cookie is HTTP-only, secure, strict
+SameSite, and scoped with the `__Host-MxGatewayDashboard` name. Logout clears
+that cookie. Login and logout posts use anti-forgery validation, and dashboard
+API keys are not accepted in query strings. `Dashboard:AllowAnonymousLocalhost`
+allows only loopback requests to bypass the dashboard cookie requirement and
+defaults to `false`.
+
 Recommended scopes:
 
 - `session:open`
@@ -868,6 +891,11 @@ behavior unless an explicit non-parity backend is designed.
 Gateway tests should be able to run without installed MXAccess by using fake
 workers and fake transports.
 
+Use `FakeWorkerHarness` for tests that need real gateway-to-worker framing,
+handshake, command, event, fault, or malformed-protocol behavior without loading
+MXAccess COM. See [Gateway Testing](./GatewayTesting.md) for the harness scope
+and focused test commands.
+
 Focused tests:
 
 - session state transitions,

docs/implementation-plan-mxaccess-worker.md

@@ -189,6 +189,8 @@ Tests:
 
 Labels: `area:worker`, `type:feature`, `priority:p0`
 
+Status: implemented.
+
 Deliverables:
 
 - `Register`,
@@ -216,6 +218,8 @@ Live tests:
 
 Labels: `area:worker`, `type:feature`, `priority:p0`
 
+Status: implemented.
+
 Deliverables:
 
 - `AddItem`,
@@ -447,4 +451,3 @@ Acceptance criteria:
 
 - each public method has planned parity fixture or documented gap,
 - gateway results preserve HRESULT/status/value/event shape.
-

docs/mxaccess-worker-instance-design.md

@@ -294,7 +294,10 @@ creates `LMXProxyServerClass` through `MxAccessComObjectFactory` on the STA,
 attaches `MxAccessBaseEventSink`, and returns `WorkerReady` only after those
 steps succeed. `MxAccessSession` keeps the raw COM object private, records the
 STA managed thread id that created it, detaches the base event sink during
-disposal, and releases the COM reference on the STA.
+disposal, and releases the COM reference on the STA. After creation,
+`MxAccessStaSession` owns a `StaCommandDispatcher` backed by
+`MxAccessCommandExecutor`; `DispatchAsync` queues contract commands back to the
+same STA instead of exposing the COM object to callers.
 
 Creation rules:
 
@@ -414,6 +417,40 @@ Diagnostics:
 Implement method-specific dispatch instead of a generic string method invoker.
 Parity tests need stable command-specific request and reply shapes.
 
+`MxAccessCommandExecutor` implements the first command pair:
+
+- `Register` calls `LMXProxyServerClass.Register` with the requested client
+  name and preserves the returned server handle in both `ReturnValue` and
+  `RegisterReply.ServerHandle`.
+- `Unregister` calls `LMXProxyServerClass.Unregister` with the requested server
+  handle. The reply has no method-specific payload because the public MXAccess
+  method returns `void`.
+
+Both commands set `Hresult` to `0` only after the COM call returns normally.
+COM exceptions flow through `StaCommandDispatcher`, which captures the thrown
+HRESULT and converts the reply to `ProtocolStatusCode.MxaccessFailure`.
+`MxAccessStaSession.GetRegisteredServerHandlesAsync` returns an STA-read
+snapshot of tracked server handles for diagnostics and future cleanup logic.
+
+`MxAccessCommandExecutor` also implements the item lifecycle commands:
+
+- `AddItem` calls `LMXProxyServerClass.AddItem` with the requested server
+  handle and item definition. It preserves the returned item handle in both
+  `ReturnValue` and `AddItemReply.ItemHandle`.
+- `AddItem2` calls `LMXProxyServerClass.AddItem2` with the requested server
+  handle, item definition, and context string. The context string is passed to
+  MXAccess exactly as received.
+- `RemoveItem` calls `LMXProxyServerClass.RemoveItem` with the requested server
+  handle and item handle. The reply has no method-specific payload because the
+  public MXAccess method returns `void`.
+
+The worker records item handles only after `AddItem` or `AddItem2` returns
+normally, and removes item handles only after `RemoveItem` returns normally.
+The registry does not prevalidate server or item handles, so invalid and
+cross-server handle behavior remains owned by MXAccess. COM exceptions continue
+through `StaCommandDispatcher`, which preserves the HRESULT and leaves
+diagnostic registry state unchanged for failed cleanup calls.
+
 ## Handle Registry
 
 The worker should track MXAccess state for diagnostics and cleanup, while still
@@ -434,6 +471,10 @@ Rules:
 
 - Do not invent handles.
 - Do not rewrite handles returned by MXAccess.
+- Record server handles only after `Register` succeeds.
+- Remove server handles only after `Unregister` succeeds.
+- Record item handles only after `AddItem` or `AddItem2` succeeds.
+- Remove item handles only after `RemoveItem` succeeds.
 - Preserve invalid-handle behavior from MXAccess.
 - Preserve cross-server handle behavior from MXAccess.
 - Use registry state for cleanup and diagnostics, not semantic correction.
@@ -677,6 +718,10 @@ Live MXAccess tests:
 
 Live tests should be opt-in and clearly marked because they depend on installed
 MXAccess COM and provider state.
+The worker test suite uses `MXGATEWAY_RUN_LIVE_MXACCESS_TESTS=1` for these
+tests. `AddItem` uses `TestChildObject.TestInt` by default and accepts an
+override through `MXGATEWAY_LIVE_MXACCESS_ITEM`; `AddItem2` uses the captured
+parity fixture shape `AddItem2("TestInt", "TestChildObject")`.
 
 ## Initial Implementation Slice
 

gateway.md

@@ -109,6 +109,22 @@ histograms through .NET `Meter` and a snapshot API that dashboard services can
 project without binding to a metrics exporter.
 `DashboardSnapshotService` projects sessions, workers, metrics, faults, and
 effective configuration into immutable DTOs for read-only dashboard rendering.
+The Blazor Server dashboard renders those snapshots at `/dashboard`,
+`/dashboard/sessions`, `/dashboard/workers`, `/dashboard/events`, and
+`/dashboard/settings`. Components subscribe to
+`IDashboardSnapshotService.WatchSnapshotsAsync()` and update on the configured
+snapshot interval without mutating session or worker state. The dashboard uses
+local Bootstrap CSS and JavaScript plus a small local stylesheet; it does not
+use a Blazor UI component library.
+
+Dashboard routes use the same API-key verifier as gRPC. `/dashboard/login`
+accepts the API key in a form body, validates the configured `admin` scope,
+and issues an HTTP-only secure cookie for subsequent dashboard requests.
+`/dashboard/logout` clears that cookie. Login and logout posts validate
+anti-forgery tokens, and API keys are never accepted through query strings.
+`Dashboard:AllowAnonymousLocalhost` can bypass the cookie requirement for
+loopback requests only when explicitly enabled. Setting
+`MxGateway:Dashboard:Enabled` to `false` leaves the dashboard routes unmapped.
 
 ### Worker Process
 
@@ -520,11 +536,7 @@ Worker policy:
 
 - bounded outbound event channel,
 - never block MXAccess event handler on pipe writes,
-- if the outbound channel is full, apply configured policy:
-  - disconnect session,
-  - drop oldest low-priority data-change events,
-  - coalesce data changes by item handle,
-  - or block briefly then fault.
+- fail the worker session when the outbound channel is full.
 
 For full parity testing, default should be fail-fast rather than silent drop.
 For production high-rate telemetry, add explicit coalescing modes.
@@ -533,9 +545,15 @@ Gateway policy:
 
 - one event sequencer per session,
 - preserve per-session event order,
-- support multiple client event subscribers only if explicitly required,
-- apply backpressure from slow gRPC streams,
-- disconnect or coalesce according to client-selected mode.
+- allow one active client event subscriber per session,
+- reject a second subscriber with a clear session error,
+- use a bounded `EventStreamService` queue between worker events and gRPC
+  writes,
+- fault the session when the bounded stream queue overflows,
+- detach the subscriber when the stream is canceled.
+
+The gateway forwards only events reported by the worker. It does not synthesize
+`OperationComplete` from write completion, command replies, or status frames.
 
 ## Isolation And Fault Handling
 
@@ -857,10 +875,11 @@ translation code testable.
 The gateway maps `MxAccessGateway` to `MxAccessGatewayService`. The service
 implements `OpenSession`, `CloseSession`, `Invoke`, and `StreamEvents` by
 validating public requests, delegating session work to `ISessionManager`, and
-using explicit mapper code for public-to-worker commands, worker replies, and
-events. Missing sessions and transport failures return gRPC status errors;
-worker command replies preserve MXAccess HRESULT and status details in the
-public reply.
+using explicit mapper code for public-to-worker commands and worker replies.
+`StreamEvents` delegates subscriber ownership, ordering, and backpressure to
+`EventStreamService`. Missing sessions and transport failures return gRPC
+status errors; worker command replies preserve MXAccess HRESULT and status
+details in the public reply.
 
 ## C# Worker Versus C++ Worker
 

src/MxGateway.Server/Dashboard/Components/App.razor

@@ -0,0 +1,34 @@
+@inject IOptions<GatewayOptions> GatewayOptions
+
+<!doctype html>
+<html lang="en">
+<head>
+    <meta charset="utf-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1" />
+    <base href="@DashboardBaseHref" />
+    <link rel="stylesheet" href="/lib/bootstrap/css/bootstrap.min.css" />
+    <link rel="stylesheet" href="/css/dashboard.css" />
+    <HeadOutlet @rendermode="InteractiveServer" />
+</head>
+<body class="dashboard-body">
+    <Routes @rendermode="InteractiveServer" />
+    <script src="/lib/bootstrap/js/bootstrap.bundle.min.js"></script>
+    <script src="_framework/blazor.web.js"></script>
+</body>
+</html>
+
+@code {
+    private string DashboardBaseHref
+    {
+        get
+        {
+            string pathBase = GatewayOptions.Value.Dashboard.PathBase.TrimEnd('/');
+            if (string.IsNullOrWhiteSpace(pathBase))
+            {
+                pathBase = "/dashboard";
+            }
+
+            return $"{pathBase}/";
+        }
+    }
+}

src/MxGateway.Server/Dashboard/Components/DashboardDisplay.cs

@@ -0,0 +1,30 @@
+namespace MxGateway.Server.Dashboard.Components;
+
+public static class DashboardDisplay
+{
+    public static string DateTime(DateTimeOffset? value)
+    {
+        return value.HasValue
+            ? value.Value.UtcDateTime.ToString("yyyy-MM-dd HH:mm:ss 'UTC'", System.Globalization.CultureInfo.InvariantCulture)
+            : "-";
+    }
+
+    public static string Duration(TimeSpan value)
+    {
+        return value.TotalDays >= 1
+            ? value.ToString(@"d\.hh\:mm\:ss", System.Globalization.CultureInfo.InvariantCulture)
+            : value.ToString(@"hh\:mm\:ss", System.Globalization.CultureInfo.InvariantCulture);
+    }
+
+    public static string Text(string? value)
+    {
+        return string.IsNullOrWhiteSpace(value) ? "-" : value;
+    }
+
+    public static long MetricValue(DashboardSnapshot snapshot, string name, string? dimension = null)
+    {
+        return snapshot.Metrics.FirstOrDefault(metric =>
+            string.Equals(metric.Name, name, StringComparison.Ordinal)
+            && string.Equals(metric.Dimension, dimension, StringComparison.Ordinal))?.Value ?? 0;
+    }
+}

src/MxGateway.Server/Dashboard/Components/DashboardPageBase.cs

@@ -0,0 +1,48 @@
+using Microsoft.AspNetCore.Components;
+
+namespace MxGateway.Server.Dashboard.Components;
+
+public abstract class DashboardPageBase : ComponentBase, IAsyncDisposable
+{
+    private readonly CancellationTokenSource _disposeCancellation = new();
+    private Task? _watchTask;
+
+    [Inject]
+    protected IDashboardSnapshotService SnapshotService { get; set; } = null!;
+
+    protected DashboardSnapshot? Snapshot { get; private set; }
+
+    protected override void OnInitialized()
+    {
+        _watchTask = WatchSnapshotsAsync();
+    }
+
+    public async ValueTask DisposeAsync()
+    {
+        await _disposeCancellation.CancelAsync().ConfigureAwait(false);
+        if (_watchTask is not null)
+        {
+            await _watchTask.ConfigureAwait(false);
+        }
+
+        _disposeCancellation.Dispose();
+        GC.SuppressFinalize(this);
+    }
+
+    private async Task WatchSnapshotsAsync()
+    {
+        try
+        {
+            await foreach (DashboardSnapshot snapshot in SnapshotService
+                .WatchSnapshotsAsync(_disposeCancellation.Token)
+                .ConfigureAwait(false))
+            {
+                Snapshot = snapshot;
+                await InvokeAsync(StateHasChanged).ConfigureAwait(false);
+            }
+        }
+        catch (OperationCanceledException) when (_disposeCancellation.IsCancellationRequested)
+        {
+        }
+    }
+}

src/MxGateway.Server/Dashboard/Components/Layout/DashboardLayout.razor

@@ -0,0 +1,53 @@
+@inherits LayoutComponentBase
+@inject IOptions<GatewayOptions> GatewayOptions
+
+<div class="dashboard-shell">
+    <nav class="navbar navbar-expand-lg bg-body border-bottom dashboard-navbar">
+        <div class="container-fluid">
+            <a class="navbar-brand" href="">MXAccess Gateway</a>
+            <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#dashboardNav"
+                    aria-controls="dashboardNav" aria-expanded="false" aria-label="Toggle navigation">
+                <span class="navbar-toggler-icon"></span>
+            </button>
+            <div class="collapse navbar-collapse" id="dashboardNav">
+                <ul class="navbar-nav me-auto mb-2 mb-lg-0">
+                    <li class="nav-item">
+                        <NavLink class="nav-link" href="" Match="NavLinkMatch.All">Overview</NavLink>
+                    </li>
+                    <li class="nav-item">
+                        <NavLink class="nav-link" href="sessions">Sessions</NavLink>
+                    </li>
+                    <li class="nav-item">
+                        <NavLink class="nav-link" href="workers">Workers</NavLink>
+                    </li>
+                    <li class="nav-item">
+                        <NavLink class="nav-link" href="events">Events</NavLink>
+                    </li>
+                    <li class="nav-item">
+                        <NavLink class="nav-link" href="settings">Settings</NavLink>
+                    </li>
+                </ul>
+                <form method="post" action="@DashboardPath("/logout")" class="d-flex">
+                    <AntiforgeryToken />
+                    <button class="btn btn-outline-secondary btn-sm" type="submit">Sign out</button>
+                </form>
+            </div>
+        </div>
+    </nav>
+    <main class="container-fluid dashboard-content">
+        @Body
+    </main>
+</div>
+
+@code {
+    private string DashboardPath(string relativePath)
+    {
+        string pathBase = GatewayOptions.Value.Dashboard.PathBase.TrimEnd('/');
+        if (string.IsNullOrWhiteSpace(pathBase))
+        {
+            pathBase = "/dashboard";
+        }
+
+        return $"{pathBase}{relativePath}";
+    }
+}

src/MxGateway.Server/Dashboard/Components/Pages/DashboardHome.razor

@@ -0,0 +1,37 @@
+@page "/"
+@inherits DashboardPageBase
+
+<PageTitle>MXAccess Gateway Dashboard</PageTitle>
+
+@if (Snapshot is null)
+{
+    <div class="empty-state">Loading dashboard snapshot.</div>
+}
+else
+{
+    <div class="dashboard-page-header">
+        <div>
+            <h1>Overview</h1>
+            <div class="text-secondary">Generated @DashboardDisplay.DateTime(Snapshot.GeneratedAt)</div>
+        </div>
+        <StatusBadge Text="@Snapshot.GatewayStatus" />
+    </div>
+
+    <section class="metric-grid">
+        <MetricCard Label="Uptime" Value="@DashboardDisplay.Duration(Snapshot.GatewayUptime)" Detail="@Snapshot.GatewayVersion" />
+        <MetricCard Label="Open Sessions" Value="@DashboardDisplay.MetricValue(Snapshot, "mxgateway.sessions.open").ToString(System.Globalization.CultureInfo.InvariantCulture)" />
+        <MetricCard Label="Workers Running" Value="@DashboardDisplay.MetricValue(Snapshot, "mxgateway.workers.running").ToString(System.Globalization.CultureInfo.InvariantCulture)" />
+        <MetricCard Label="Event Queue Depth" Value="@DashboardDisplay.MetricValue(Snapshot, "mxgateway.events.queue.depth").ToString(System.Globalization.CultureInfo.InvariantCulture)" />
+        <MetricCard Label="Commands Failed" Value="@DashboardDisplay.MetricValue(Snapshot, "mxgateway.commands.failed").ToString(System.Globalization.CultureInfo.InvariantCulture)" />
+        <MetricCard Label="Events Received" Value="@DashboardDisplay.MetricValue(Snapshot, "mxgateway.events.received").ToString(System.Globalization.CultureInfo.InvariantCulture)" />
+        <MetricCard Label="Faults" Value="@DashboardDisplay.MetricValue(Snapshot, "mxgateway.faults").ToString(System.Globalization.CultureInfo.InvariantCulture)" />
+        <MetricCard Label="Queue Overflows" Value="@DashboardDisplay.MetricValue(Snapshot, "mxgateway.queues.overflows").ToString(System.Globalization.CultureInfo.InvariantCulture)" />
+    </section>
+
+    <section class="dashboard-section">
+        <div class="section-heading">
+            <h2>Recent Faults</h2>
+        </div>
+        <FaultList Faults="@Snapshot.Faults" />
+    </section>
+}

src/MxGateway.Server/Dashboard/Components/Pages/EventsPage.razor

@@ -0,0 +1,64 @@
+@page "/events"
+@inherits DashboardPageBase
+
+<PageTitle>Dashboard Events</PageTitle>
+
+@if (Snapshot is null)
+{
+    <div class="empty-state">Loading event diagnostics.</div>
+}
+else
+{
+    <div class="dashboard-page-header">
+        <div>
+            <h1>Events</h1>
+            <div class="text-secondary">Generated @DashboardDisplay.DateTime(Snapshot.GeneratedAt)</div>
+        </div>
+    </div>
+
+    <section class="metric-grid compact">
+        <MetricCard Label="Events Received" Value="@DashboardDisplay.MetricValue(Snapshot, "mxgateway.events.received").ToString(System.Globalization.CultureInfo.InvariantCulture)" />
+        <MetricCard Label="Event Queue Depth" Value="@DashboardDisplay.MetricValue(Snapshot, "mxgateway.events.queue.depth").ToString(System.Globalization.CultureInfo.InvariantCulture)" />
+        <MetricCard Label="Queue Overflows" Value="@DashboardDisplay.MetricValue(Snapshot, "mxgateway.queues.overflows").ToString(System.Globalization.CultureInfo.InvariantCulture)" />
+        <MetricCard Label="Stream Disconnects" Value="@DashboardDisplay.MetricValue(Snapshot, "mxgateway.grpc.streams.disconnected").ToString(System.Globalization.CultureInfo.InvariantCulture)" />
+    </section>
+
+    <section class="dashboard-section">
+        <div class="section-heading">
+            <h2>Event Families</h2>
+        </div>
+        @if (EventFamilyMetrics.Count == 0)
+        {
+            <div class="empty-state">No event family counters recorded.</div>
+        }
+        else
+        {
+            <div class="table-responsive">
+                <table class="table table-sm dashboard-table">
+                    <thead>
+                        <tr>
+                            <th scope="col">Family</th>
+                            <th scope="col">Count</th>
+                        </tr>
+                    </thead>
+                    <tbody>
+                        @foreach (DashboardMetricSummary metric in EventFamilyMetrics)
+                        {
+                            <tr>
+                                <td>@metric.Dimension</td>
+                                <td>@metric.Value</td>
+                            </tr>
+                        }
+                    </tbody>
+                </table>
+            </div>
+        }
+    </section>
+}
+
+@code {
+    private IReadOnlyList<DashboardMetricSummary> EventFamilyMetrics => Snapshot?.Metrics
+        .Where(metric => metric.Name == "mxgateway.events.received" && metric.Dimension is not null)
+        .OrderBy(metric => metric.Dimension, StringComparer.OrdinalIgnoreCase)
+        .ToArray() ?? [];
+}

src/MxGateway.Server/Dashboard/Components/Pages/SessionDetailsPage.razor

@@ -0,0 +1,69 @@
+@page "/sessions/{SessionId}"
+@inherits DashboardPageBase
+
+<PageTitle>Dashboard Session</PageTitle>
+
+@if (Snapshot is null)
+{
+    <div class="empty-state">Loading session.</div>
+}
+else if (CurrentSession is null)
+{
+    <section class="dashboard-section">
+        <h1 class="h4 mb-3">Session Not Found</h1>
+        <p class="mb-0">The session is not present in the current snapshot.</p>
+    </section>
+}
+else
+{
+    <div class="dashboard-page-header">
+        <div>
+            <h1>Session Details</h1>
+            <div class="text-secondary"><code>@CurrentSession.SessionId</code></div>
+        </div>
+        <StatusBadge Text="@CurrentSession.State.ToString()" />
+    </div>
+
+    <section class="dashboard-section">
+        <div class="section-heading">
+            <h2>Session</h2>
+        </div>
+        <div class="table-responsive">
+            <table class="table table-sm dashboard-table details-table">
+                <tbody>
+                    <tr><th scope="row">Backend</th><td>@CurrentSession.BackendName</td></tr>
+                    <tr><th scope="row">Client identity</th><td>@DashboardDisplay.Text(CurrentSession.ClientIdentity)</td></tr>
+                    <tr><th scope="row">Client session</th><td>@DashboardDisplay.Text(CurrentSession.ClientSessionName)</td></tr>
+                    <tr><th scope="row">Client correlation</th><td>@DashboardDisplay.Text(CurrentSession.ClientCorrelationId)</td></tr>
+                    <tr><th scope="row">Opened</th><td>@DashboardDisplay.DateTime(CurrentSession.OpenedAt)</td></tr>
+                    <tr><th scope="row">Last activity</th><td>@DashboardDisplay.DateTime(CurrentSession.LastClientActivityAt)</td></tr>
+                    <tr><th scope="row">Lease expires</th><td>@DashboardDisplay.DateTime(CurrentSession.LeaseExpiresAt)</td></tr>
+                    <tr><th scope="row">Last fault</th><td>@DashboardDisplay.Text(CurrentSession.LastFault)</td></tr>
+                </tbody>
+            </table>
+        </div>
+    </section>
+
+    <section class="dashboard-section">
+        <div class="section-heading">
+            <h2>Worker</h2>
+        </div>
+        <div class="table-responsive">
+            <table class="table table-sm dashboard-table details-table">
+                <tbody>
+                    <tr><th scope="row">Process id</th><td>@(CurrentSession.WorkerProcessId?.ToString(System.Globalization.CultureInfo.InvariantCulture) ?? "-")</td></tr>
+                    <tr><th scope="row">State</th><td><StatusBadge Text="@(CurrentSession.WorkerState?.ToString() ?? "-")" /></td></tr>
+                    <tr><th scope="row">Last heartbeat</th><td>@DashboardDisplay.DateTime(CurrentSession.LastWorkerHeartbeatAt)</td></tr>
+                </tbody>
+            </table>
+        </div>
+    </section>
+}
+
+@code {
+    [Parameter]
+    public string SessionId { get; set; } = string.Empty;
+
+    private DashboardSessionSummary? CurrentSession => Snapshot?.Sessions.FirstOrDefault(session =>
+        string.Equals(session.SessionId, SessionId, StringComparison.Ordinal));
+}

src/MxGateway.Server/Dashboard/Components/Pages/SessionsPage.razor

@@ -0,0 +1,67 @@
+@page "/sessions"
+@inherits DashboardPageBase
+
+<PageTitle>Dashboard Sessions</PageTitle>
+
+@if (Snapshot is null)
+{
+    <div class="empty-state">Loading sessions.</div>
+}
+else
+{
+    <div class="dashboard-page-header">
+        <div>
+            <h1>Sessions</h1>
+            <div class="text-secondary">@Snapshot.Sessions.Count session rows</div>
+        </div>
+    </div>
+
+    <section class="dashboard-section">
+        @if (Snapshot.Sessions.Count == 0)
+        {
+            <div class="empty-state">No sessions are active or retained.</div>
+        }
+        else
+        {
+            <div class="table-responsive">
+                <table class="table table-sm align-middle dashboard-table">
+                    <thead>
+                        <tr>
+                            <th scope="col">Session</th>
+                            <th scope="col">State</th>
+                            <th scope="col">Client</th>
+                            <th scope="col">Backend</th>
+                            <th scope="col">Worker</th>
+                            <th scope="col">Opened</th>
+                            <th scope="col">Activity</th>
+                            <th scope="col">Heartbeat</th>
+                            <th scope="col">Fault</th>
+                        </tr>
+                    </thead>
+                    <tbody>
+                        @foreach (DashboardSessionSummary session in Snapshot.Sessions)
+                        {
+                            <tr>
+                                <td><NavLink href="@($"sessions/{Uri.EscapeDataString(session.SessionId)}")"><code>@session.SessionId</code></NavLink></td>
+                                <td><StatusBadge Text="@session.State.ToString()" /></td>
+                                <td>@DashboardDisplay.Text(session.ClientIdentity)</td>
+                                <td>@session.BackendName</td>
+                                <td>
+                                    @(session.WorkerProcessId?.ToString(System.Globalization.CultureInfo.InvariantCulture) ?? "-")
+                                    @if (session.WorkerState is not null)
+                                    {
+                                        <span class="ms-1"><StatusBadge Text="@session.WorkerState.ToString()" /></span>
+                                    }
+                                </td>
+                                <td>@DashboardDisplay.DateTime(session.OpenedAt)</td>
+                                <td>@DashboardDisplay.DateTime(session.LastClientActivityAt)</td>
+                                <td>@DashboardDisplay.DateTime(session.LastWorkerHeartbeatAt)</td>
+                                <td>@DashboardDisplay.Text(session.LastFault)</td>
+                            </tr>
+                        }
+                    </tbody>
+                </table>
+            </div>
+        }
+    </section>
+}

src/MxGateway.Server/Dashboard/Components/Pages/SettingsPage.razor

@@ -0,0 +1,47 @@
+@page "/settings"
+@inherits DashboardPageBase
+
+<PageTitle>Dashboard Settings</PageTitle>
+
+@if (Snapshot is null)
+{
+    <div class="empty-state">Loading settings.</div>
+}
+else
+{
+    <div class="dashboard-page-header">
+        <div>
+            <h1>Settings</h1>
+            <div class="text-secondary">Effective gateway configuration</div>
+        </div>
+    </div>
+
+    <section class="dashboard-section">
+        <div class="table-responsive">
+            <table class="table table-sm dashboard-table details-table">
+                <tbody>
+                    <tr><th scope="row">Authentication mode</th><td>@Snapshot.Configuration.Authentication.Mode</td></tr>
+                    <tr><th scope="row">Auth database</th><td><code>@Snapshot.Configuration.Authentication.SqlitePath</code></td></tr>
+                    <tr><th scope="row">Pepper secret</th><td>@Snapshot.Configuration.Authentication.PepperSecretName</td></tr>
+                    <tr><th scope="row">Run migrations</th><td>@Snapshot.Configuration.Authentication.RunMigrationsOnStartup</td></tr>
+                    <tr><th scope="row">Worker executable</th><td><code>@Snapshot.Configuration.Worker.ExecutablePath</code></td></tr>
+                    <tr><th scope="row">Worker architecture</th><td>@Snapshot.Configuration.Worker.RequiredArchitecture</td></tr>
+                    <tr><th scope="row">Startup timeout</th><td>@Snapshot.Configuration.Worker.StartupTimeoutSeconds seconds</td></tr>
+                    <tr><th scope="row">Shutdown timeout</th><td>@Snapshot.Configuration.Worker.ShutdownTimeoutSeconds seconds</td></tr>
+                    <tr><th scope="row">Heartbeat grace</th><td>@Snapshot.Configuration.Worker.HeartbeatGraceSeconds seconds</td></tr>
+                    <tr><th scope="row">Default command timeout</th><td>@Snapshot.Configuration.Sessions.DefaultCommandTimeoutSeconds seconds</td></tr>
+                    <tr><th scope="row">Max sessions</th><td>@Snapshot.Configuration.Sessions.MaxSessions</td></tr>
+                    <tr><th scope="row">Event queue capacity</th><td>@Snapshot.Configuration.Events.QueueCapacity</td></tr>
+                    <tr><th scope="row">Backpressure policy</th><td>@Snapshot.Configuration.Events.BackpressurePolicy</td></tr>
+                    <tr><th scope="row">Dashboard enabled</th><td>@Snapshot.Configuration.Dashboard.Enabled</td></tr>
+                    <tr><th scope="row">Dashboard path</th><td>@Snapshot.Configuration.Dashboard.PathBase</td></tr>
+                    <tr><th scope="row">Require admin scope</th><td>@Snapshot.Configuration.Dashboard.RequireAdminScope</td></tr>
+                    <tr><th scope="row">Anonymous localhost</th><td>@Snapshot.Configuration.Dashboard.AllowAnonymousLocalhost</td></tr>
+                    <tr><th scope="row">Snapshot interval</th><td>@Snapshot.Configuration.Dashboard.SnapshotIntervalMilliseconds ms</td></tr>
+                    <tr><th scope="row">Show tag values</th><td>@Snapshot.Configuration.Dashboard.ShowTagValues</td></tr>
+                    <tr><th scope="row">Worker protocol</th><td>@Snapshot.Configuration.Protocol.WorkerProtocolVersion</td></tr>
+                </tbody>
+            </table>
+        </div>
+    </section>
+}

src/MxGateway.Server/Dashboard/Components/Pages/WorkersPage.razor

@@ -0,0 +1,53 @@
+@page "/workers"
+@inherits DashboardPageBase
+
+<PageTitle>Dashboard Workers</PageTitle>
+
+@if (Snapshot is null)
+{
+    <div class="empty-state">Loading workers.</div>
+}
+else
+{
+    <div class="dashboard-page-header">
+        <div>
+            <h1>Workers</h1>
+            <div class="text-secondary">@Snapshot.Workers.Count worker rows</div>
+        </div>
+    </div>
+
+    <section class="dashboard-section">
+        @if (Snapshot.Workers.Count == 0)
+        {
+            <div class="empty-state">No worker processes are attached.</div>
+        }
+        else
+        {
+            <div class="table-responsive">
+                <table class="table table-sm align-middle dashboard-table">
+                    <thead>
+                        <tr>
+                            <th scope="col">Process</th>
+                            <th scope="col">State</th>
+                            <th scope="col">Session</th>
+                            <th scope="col">Heartbeat</th>
+                            <th scope="col">Fault</th>
+                        </tr>
+                    </thead>
+                    <tbody>
+                        @foreach (DashboardWorkerSummary worker in Snapshot.Workers)
+                        {
+                            <tr>
+                                <td>@(worker.ProcessId?.ToString(System.Globalization.CultureInfo.InvariantCulture) ?? "-")</td>
+                                <td><StatusBadge Text="@worker.State.ToString()" /></td>
+                                <td><NavLink href="@($"sessions/{Uri.EscapeDataString(worker.SessionId)}")"><code>@worker.SessionId</code></NavLink></td>
+                                <td>@DashboardDisplay.DateTime(worker.LastHeartbeatAt)</td>
+                                <td>@DashboardDisplay.Text(worker.LastFault)</td>
+                            </tr>
+                        }
+                    </tbody>
+                </table>
+            </div>
+        }
+    </section>
+}

src/MxGateway.Server/Dashboard/Components/Routes.razor

@@ -0,0 +1,15 @@
+<Router AppAssembly="@typeof(Routes).Assembly">
+    <Found Context="routeData">
+        <RouteView RouteData="@routeData" DefaultLayout="@typeof(DashboardLayout)" />
+        <FocusOnNavigate RouteData="@routeData" Selector="h1" />
+    </Found>
+    <NotFound>
+        <LayoutView Layout="@typeof(DashboardLayout)">
+            <PageTitle>Dashboard - Not Found</PageTitle>
+            <section class="dashboard-section">
+                <h1 class="h4 mb-3">Not Found</h1>
+                <p class="mb-0">The requested dashboard page does not exist.</p>
+            </section>
+        </LayoutView>
+    </NotFound>
+</Router>

src/MxGateway.Server/Dashboard/Components/Shared/FaultList.razor

@@ -0,0 +1,39 @@
+@if (Faults.Count == 0)
+{
+    <div class="empty-state">No faults recorded.</div>
+}
+else
+{
+    <div class="table-responsive">
+        <table class="table table-sm align-middle dashboard-table">
+            <thead>
+                <tr>
+                    <th scope="col">Observed</th>
+                    <th scope="col">Source</th>
+                    <th scope="col">Session</th>
+                    <th scope="col">Worker</th>
+                    <th scope="col">State</th>
+                    <th scope="col">Message</th>
+                </tr>
+            </thead>
+            <tbody>
+                @foreach (DashboardFaultSummary fault in Faults)
+                {
+                    <tr>
+                        <td>@DashboardDisplay.DateTime(fault.ObservedAt)</td>
+                        <td>@fault.Source</td>
+                        <td><code>@DashboardDisplay.Text(fault.SessionId)</code></td>
+                        <td>@(fault.WorkerProcessId?.ToString(System.Globalization.CultureInfo.InvariantCulture) ?? "-")</td>
+                        <td><StatusBadge Text="@fault.State" /></td>
+                        <td>@fault.Message</td>
+                    </tr>
+                }
+            </tbody>
+        </table>
+    </div>
+}
+
+@code {
+    [Parameter]
+    public IReadOnlyList<DashboardFaultSummary> Faults { get; set; } = [];
+}

src/MxGateway.Server/Dashboard/Components/Shared/MetricCard.razor

@@ -0,0 +1,21 @@
+<div class="card metric-card h-100">
+    <div class="card-body">
+        <div class="metric-label">@Label</div>
+        <div class="metric-value">@Value</div>
+        @if (!string.IsNullOrWhiteSpace(Detail))
+        {
+            <div class="metric-detail">@Detail</div>
+        }
+    </div>
+</div>
+
+@code {
+    [Parameter]
+    public string Label { get; set; } = string.Empty;
+
+    [Parameter]
+    public string Value { get; set; } = string.Empty;
+
+    [Parameter]
+    public string? Detail { get; set; }
+}

src/MxGateway.Server/Dashboard/Components/Shared/StatusBadge.razor

@@ -0,0 +1,15 @@
+<span class="badge @CssClass">@Text</span>
+
+@code {
+    [Parameter]
+    public string? Text { get; set; }
+
+    private string CssClass => Text switch
+    {
+        "Ready" or "Healthy" => "text-bg-success",
+        "Creating" or "StartingWorker" or "WaitingForPipe" or "InitializingWorker" or "Closing" => "text-bg-info",
+        "Closed" => "text-bg-secondary",
+        "Faulted" => "text-bg-danger",
+        _ => "text-bg-light text-dark border"
+    };
+}

src/MxGateway.Server/Dashboard/Components/_Imports.razor

@@ -0,0 +1,12 @@
+@using Microsoft.AspNetCore.Components.Authorization
+@using Microsoft.AspNetCore.Components.Forms
+@using Microsoft.AspNetCore.Components.Routing
+@using Microsoft.AspNetCore.Components.Web
+@using Microsoft.Extensions.Options
+@using MxGateway.Contracts.Proto
+@using MxGateway.Server.Configuration
+@using MxGateway.Server.Dashboard
+@using MxGateway.Server.Dashboard.Components.Layout
+@using MxGateway.Server.Dashboard.Components.Shared
+@using MxGateway.Server.Workers
+@using static Microsoft.AspNetCore.Components.Web.RenderMode

src/MxGateway.Server/Dashboard/DashboardAuthenticationDefaults.cs

@@ -0,0 +1,10 @@
+namespace MxGateway.Server.Dashboard;
+
+public static class DashboardAuthenticationDefaults
+{
+    public const string AuthenticationScheme = "MxGateway.Dashboard";
+    public const string AuthorizationPolicy = "MxGateway.Dashboard";
+    public const string ScopeClaimType = "scope";
+    public const string KeyPrefixClaimType = "mxgateway:key_prefix";
+    public const string CookieName = "__Host-MxGatewayDashboard";
+}

src/MxGateway.Server/Dashboard/DashboardAuthenticationResult.cs

@@ -0,0 +1,19 @@
+using System.Security.Claims;
+
+namespace MxGateway.Server.Dashboard;
+
+public sealed record DashboardAuthenticationResult(
+    bool Succeeded,
+    ClaimsPrincipal? Principal,
+    string? FailureMessage)
+{
+    public static DashboardAuthenticationResult Success(ClaimsPrincipal principal)
+    {
+        return new DashboardAuthenticationResult(true, principal, null);
+    }
+
+    public static DashboardAuthenticationResult Fail(string failureMessage)
+    {
+        return new DashboardAuthenticationResult(false, null, failureMessage);
+    }
+}

src/MxGateway.Server/Dashboard/DashboardAuthenticator.cs

@@ -0,0 +1,81 @@
+using System.Security.Claims;
+using Microsoft.Extensions.Options;
+using MxGateway.Server.Configuration;
+using MxGateway.Server.Security.Authentication;
+using MxGateway.Server.Security.Authorization;
+
+namespace MxGateway.Server.Dashboard;
+
+public sealed class DashboardAuthenticator(
+    IApiKeyVerifier apiKeyVerifier,
+    IOptions<GatewayOptions> options) : IDashboardAuthenticator
+{
+    private const string GenericFailureMessage = "The API key is invalid or is not authorized for dashboard access.";
+
+    public async Task<DashboardAuthenticationResult> AuthenticateAsync(
+        string? apiKey,
+        CancellationToken cancellationToken)
+    {
+        if (options.Value.Authentication.Mode == AuthenticationMode.Disabled)
+        {
+            return DashboardAuthenticationResult.Success(CreatePrincipal(new ApiKeyIdentity(
+                KeyId: "authentication-disabled",
+                KeyPrefix: "authentication-disabled",
+                DisplayName: "Authentication Disabled",
+                Scopes: new HashSet<string>([GatewayScopes.Admin], StringComparer.Ordinal))));
+        }
+
+        if (string.IsNullOrWhiteSpace(apiKey))
+        {
+            return DashboardAuthenticationResult.Fail(GenericFailureMessage);
+        }
+
+        ApiKeyVerificationResult verificationResult = await apiKeyVerifier
+            .VerifyAsync(FormatAuthorizationHeader(apiKey), cancellationToken)
+            .ConfigureAwait(false);
+
+        if (!verificationResult.Succeeded || verificationResult.Identity is null)
+        {
+            return DashboardAuthenticationResult.Fail(GenericFailureMessage);
+        }
+
+        if (options.Value.Dashboard.RequireAdminScope
+            && !verificationResult.Identity.Scopes.Contains(GatewayScopes.Admin))
+        {
+            return DashboardAuthenticationResult.Fail(GenericFailureMessage);
+        }
+
+        return DashboardAuthenticationResult.Success(CreatePrincipal(verificationResult.Identity));
+    }
+
+    private static string FormatAuthorizationHeader(string apiKey)
+    {
+        string trimmedApiKey = apiKey.Trim();
+
+        return trimmedApiKey.StartsWith("Bearer ", StringComparison.OrdinalIgnoreCase)
+            ? trimmedApiKey
+            : $"Bearer {trimmedApiKey}";
+    }
+
+    private static ClaimsPrincipal CreatePrincipal(ApiKeyIdentity identity)
+    {
+        List<Claim> claims =
+        [
+            new Claim(ClaimTypes.NameIdentifier, identity.KeyId),
+            new Claim(ClaimTypes.Name, identity.DisplayName),
+            new Claim(DashboardAuthenticationDefaults.KeyPrefixClaimType, identity.KeyPrefix)
+        ];
+
+        claims.AddRange(identity.Scopes.Select(scope => new Claim(
+            DashboardAuthenticationDefaults.ScopeClaimType,
+            scope)));
+
+        ClaimsIdentity claimsIdentity = new(
+            claims,
+            DashboardAuthenticationDefaults.AuthenticationScheme,
+            ClaimTypes.Name,
+            DashboardAuthenticationDefaults.ScopeClaimType);
+
+        return new ClaimsPrincipal(claimsIdentity);
+    }
+}

src/MxGateway.Server/Dashboard/DashboardAuthorizationHandler.cs

@@ -0,0 +1,59 @@
+using System.Net;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.Extensions.Options;
+using MxGateway.Server.Configuration;
+using MxGateway.Server.Security.Authorization;
+
+namespace MxGateway.Server.Dashboard;
+
+public sealed class DashboardAuthorizationHandler(
+    IHttpContextAccessor httpContextAccessor,
+    IOptions<GatewayOptions> options) : AuthorizationHandler<DashboardAuthorizationRequirement>
+{
+    protected override Task HandleRequirementAsync(
+        AuthorizationHandlerContext context,
+        DashboardAuthorizationRequirement requirement)
+    {
+        GatewayOptions gatewayOptions = options.Value;
+
+        if (gatewayOptions.Authentication.Mode == AuthenticationMode.Disabled)
+        {
+            context.Succeed(requirement);
+
+            return Task.CompletedTask;
+        }
+
+        if (gatewayOptions.Dashboard.AllowAnonymousLocalhost && IsLoopbackRequest())
+        {
+            context.Succeed(requirement);
+
+            return Task.CompletedTask;
+        }
+
+        if (context.User.Identity?.IsAuthenticated != true)
+        {
+            return Task.CompletedTask;
+        }
+
+        if (!gatewayOptions.Dashboard.RequireAdminScope || HasAdminScope(context))
+        {
+            context.Succeed(requirement);
+        }
+
+        return Task.CompletedTask;
+    }
+
+    private bool IsLoopbackRequest()
+    {
+        IPAddress? remoteAddress = httpContextAccessor.HttpContext?.Connection.RemoteIpAddress;
+
+        return remoteAddress is not null && IPAddress.IsLoopback(remoteAddress);
+    }
+
+    private static bool HasAdminScope(AuthorizationHandlerContext context)
+    {
+        return context.User.HasClaim(
+            DashboardAuthenticationDefaults.ScopeClaimType,
+            GatewayScopes.Admin);
+    }
+}

src/MxGateway.Server/Dashboard/DashboardAuthorizationRequirement.cs

@@ -0,0 +1,5 @@
+using Microsoft.AspNetCore.Authorization;
+
+namespace MxGateway.Server.Dashboard;
+
+public sealed class DashboardAuthorizationRequirement : IAuthorizationRequirement;

src/MxGateway.Server/Dashboard/DashboardEndpointRouteBuilderExtensions.cs

@@ -0,0 +1,197 @@
+using System.Text.Encodings.Web;
+using Microsoft.AspNetCore.Antiforgery;
+using Microsoft.AspNetCore.Authentication;
+using Microsoft.AspNetCore.Http.HttpResults;
+using MxGateway.Server.Configuration;
+using MxGateway.Server.Dashboard.Components;
+
+namespace MxGateway.Server.Dashboard;
+
+public static class DashboardEndpointRouteBuilderExtensions
+{
+    public static IEndpointRouteBuilder MapGatewayDashboard(this IEndpointRouteBuilder endpoints)
+    {
+        IConfiguration configuration = endpoints.ServiceProvider.GetRequiredService<IConfiguration>();
+        IConfigurationSection dashboardSection = configuration
+            .GetSection($"{GatewayOptions.SectionName}:Dashboard");
+
+        if (bool.TryParse(dashboardSection["Enabled"], out bool enabled) && !enabled)
+        {
+            return endpoints;
+        }
+
+        string pathBase = NormalizePathBase(dashboardSection["PathBase"] ?? new DashboardOptions().PathBase);
+        RouteGroupBuilder dashboard = endpoints.MapGroup(pathBase);
+
+        dashboard.MapGet(
+                "/login",
+                (HttpContext httpContext, IAntiforgery antiforgery) => GetLoginAsync(httpContext, antiforgery, pathBase))
+            .AllowAnonymous()
+            .WithName("DashboardLogin");
+
+        dashboard.MapPost(
+                "/login",
+                (HttpContext httpContext, IAntiforgery antiforgery, IDashboardAuthenticator authenticator) =>
+                    PostLoginAsync(httpContext, antiforgery, authenticator, pathBase))
+            .AllowAnonymous()
+            .WithName("DashboardLoginPost");
+
+        dashboard.MapPost(
+                "/logout",
+                (HttpContext httpContext, IAntiforgery antiforgery) => PostLogoutAsync(httpContext, antiforgery, pathBase))
+            .RequireAuthorization(DashboardAuthenticationDefaults.AuthorizationPolicy)
+            .WithName("DashboardLogout");
+
+        dashboard.MapGet("/denied", () => Results.Content(
+                RenderPage("Access denied", "<p>The signed-in API key is not authorized for dashboard access.</p>"),
+                "text/html"))
+            .AllowAnonymous()
+            .WithName("DashboardAccessDenied");
+
+        dashboard.MapRazorComponents<App>()
+            .AddInteractiveServerRenderMode()
+            .RequireAuthorization(DashboardAuthenticationDefaults.AuthorizationPolicy);
+
+        return endpoints;
+    }
+
+    private static Task<ContentHttpResult> GetLoginAsync(
+        HttpContext httpContext,
+        IAntiforgery antiforgery,
+        string pathBase)
+    {
+        string returnUrl = SanitizeReturnUrl(
+            httpContext.Request.Query["returnUrl"].ToString(),
+            pathBase);
+
+        return Task.FromResult(TypedResults.Content(
+            RenderLoginPage(httpContext, antiforgery, returnUrl, pathBase, failureMessage: null),
+            "text/html"));
+    }
+
+    private static async Task<IResult> PostLoginAsync(
+        HttpContext httpContext,
+        IAntiforgery antiforgery,
+        IDashboardAuthenticator authenticator,
+        string pathBase)
+    {
+        await antiforgery.ValidateRequestAsync(httpContext).ConfigureAwait(false);
+
+        IFormCollection form = await httpContext.Request
+            .ReadFormAsync(httpContext.RequestAborted)
+            .ConfigureAwait(false);
+        string returnUrl = SanitizeReturnUrl(
+            form["returnUrl"].ToString(),
+            pathBase);
+
+        DashboardAuthenticationResult result = await authenticator
+            .AuthenticateAsync(form["apiKey"].ToString(), httpContext.RequestAborted)
+            .ConfigureAwait(false);
+
+        if (!result.Succeeded || result.Principal is null)
+        {
+            return TypedResults.Content(
+                RenderLoginPage(httpContext, antiforgery, returnUrl, pathBase, result.FailureMessage),
+                "text/html",
+                statusCode: StatusCodes.Status401Unauthorized);
+        }
+
+        await httpContext
+            .SignInAsync(DashboardAuthenticationDefaults.AuthenticationScheme, result.Principal)
+            .ConfigureAwait(false);
+
+        return Results.LocalRedirect(returnUrl);
+    }
+
+    private static async Task<IResult> PostLogoutAsync(
+        HttpContext httpContext,
+        IAntiforgery antiforgery,
+        string pathBase)
+    {
+        await antiforgery.ValidateRequestAsync(httpContext).ConfigureAwait(false);
+        await httpContext
+            .SignOutAsync(DashboardAuthenticationDefaults.AuthenticationScheme)
+            .ConfigureAwait(false);
+
+        return Results.LocalRedirect($"{pathBase}/login");
+    }
+
+    private static string RenderLoginPage(
+        HttpContext httpContext,
+        IAntiforgery antiforgery,
+        string returnUrl,
+        string pathBase,
+        string? failureMessage)
+    {
+        AntiforgeryTokenSet tokens = antiforgery.GetAndStoreTokens(httpContext);
+        string requestToken = tokens.RequestToken ?? string.Empty;
+        string alert = string.IsNullOrWhiteSpace(failureMessage)
+            ? string.Empty
+            : $"<p role=\"alert\">{HtmlEncoder.Default.Encode(failureMessage)}</p>";
+
+        string body = $"""
+            <section class="dashboard-login">
+                {alert}
+                <form method="post" action="{HtmlEncoder.Default.Encode(pathBase + "/login")}" class="card login-card">
+                    <div class="card-body">
+                        <input name="{tokens.FormFieldName}" type="hidden" value="{HtmlEncoder.Default.Encode(requestToken)}" />
+                        <input name="returnUrl" type="hidden" value="{HtmlEncoder.Default.Encode(returnUrl)}" />
+                        <div class="mb-3">
+                            <label for="apiKey" class="form-label">API key</label>
+                            <input id="apiKey" name="apiKey" type="password" autocomplete="off" class="form-control" />
+                        </div>
+                        <button type="submit" class="btn btn-primary">Sign in</button>
+                    </div>
+                </form>
+            </section>
+            """;
+
+        return RenderPage("Dashboard Sign In", body);
+    }
+
+    private static string RenderPage(string title, string body)
+    {
+        return $"""
+            <!doctype html>
+            <html lang="en">
+            <head>
+                <meta charset="utf-8" />
+                <meta name="viewport" content="width=device-width, initial-scale=1" />
+                <title>{HtmlEncoder.Default.Encode(title)}</title>
+                <link rel="stylesheet" href="/lib/bootstrap/css/bootstrap.min.css" />
+                <link rel="stylesheet" href="/css/dashboard.css" />
+            </head>
+            <body class="dashboard-body">
+                <main class="container py-5">
+                    <h1 class="h3 mb-4">{HtmlEncoder.Default.Encode(title)}</h1>
+                    {body}
+                </main>
+                <script src="/lib/bootstrap/js/bootstrap.bundle.min.js"></script>
+            </body>
+            </html>
+            """;
+    }
+
+    private static string NormalizePathBase(string pathBase)
+    {
+        string normalized = pathBase.TrimEnd('/');
+
+        return string.IsNullOrWhiteSpace(normalized) || !normalized.StartsWith("/", StringComparison.Ordinal)
+            ? "/dashboard"
+            : normalized;
+    }
+
+    private static string SanitizeReturnUrl(string? returnUrl, string pathBase)
+    {
+        if (string.IsNullOrWhiteSpace(returnUrl)
+            || !returnUrl.StartsWith("/", StringComparison.Ordinal)
+            || returnUrl.StartsWith("//", StringComparison.Ordinal)
+            || !returnUrl.StartsWith(pathBase, StringComparison.OrdinalIgnoreCase)
+            || Uri.TryCreate(returnUrl, UriKind.Absolute, out _))
+        {
+            return pathBase;
+        }
+
+        return returnUrl;
+    }
+}

src/MxGateway.Server/Dashboard/DashboardServiceCollectionExtensions.cs

@@ -1,3 +1,8 @@
+using Microsoft.AspNetCore.Authentication.Cookies;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.Extensions.Options;
+using MxGateway.Server.Configuration;
+
 namespace MxGateway.Server.Dashboard;
 
 public static class DashboardServiceCollectionExtensions
@@ -5,7 +10,47 @@ public static class DashboardServiceCollectionExtensions
     public static IServiceCollection AddGatewayDashboard(this IServiceCollection services)
     {
         services.AddSingleton<IDashboardSnapshotService, DashboardSnapshotService>();
+        services.AddSingleton<IDashboardAuthenticator, DashboardAuthenticator>();
+        services.AddHttpContextAccessor();
+        services.AddAntiforgery();
+        services.AddCascadingAuthenticationState();
+        services.AddRazorComponents()
+            .AddInteractiveServerComponents();
+        services
+            .AddAuthentication(DashboardAuthenticationDefaults.AuthenticationScheme)
+            .AddCookie(DashboardAuthenticationDefaults.AuthenticationScheme);
+        services.AddOptions<CookieAuthenticationOptions>(DashboardAuthenticationDefaults.AuthenticationScheme)
+            .Configure<IOptions<GatewayOptions>>(ConfigureCookieOptions);
+        services.AddAuthorization(options =>
+        {
+            options.AddPolicy(
+                DashboardAuthenticationDefaults.AuthorizationPolicy,
+                policy => policy.AddRequirements(new DashboardAuthorizationRequirement()));
+        });
+        services.AddSingleton<IAuthorizationHandler, DashboardAuthorizationHandler>();
 
         return services;
     }
+
+    private static void ConfigureCookieOptions(
+        CookieAuthenticationOptions cookieOptions,
+        IOptions<GatewayOptions> gatewayOptions)
+    {
+        string pathBase = gatewayOptions.Value.Dashboard.PathBase.TrimEnd('/');
+        if (string.IsNullOrWhiteSpace(pathBase))
+        {
+            pathBase = "/dashboard";
+        }
+
+        cookieOptions.Cookie.Name = DashboardAuthenticationDefaults.CookieName;
+        cookieOptions.Cookie.HttpOnly = true;
+        cookieOptions.Cookie.SecurePolicy = CookieSecurePolicy.Always;
+        cookieOptions.Cookie.SameSite = SameSiteMode.Strict;
+        cookieOptions.Cookie.Path = "/";
+        cookieOptions.LoginPath = $"{pathBase}/login";
+        cookieOptions.LogoutPath = $"{pathBase}/logout";
+        cookieOptions.AccessDeniedPath = $"{pathBase}/denied";
+        cookieOptions.ExpireTimeSpan = TimeSpan.FromHours(8);
+        cookieOptions.SlidingExpiration = true;
+    }
 }

src/MxGateway.Server/Dashboard/IDashboardAuthenticator.cs

@@ -0,0 +1,8 @@
+namespace MxGateway.Server.Dashboard;
+
+public interface IDashboardAuthenticator
+{
+    Task<DashboardAuthenticationResult> AuthenticateAsync(
+        string? apiKey,
+        CancellationToken cancellationToken);
+}

src/MxGateway.Server/GatewayApplication.cs

@@ -19,6 +19,10 @@ public static class GatewayApplication
         WebApplication app = builder.Build();
 
         app.UseGatewayRequestLoggingScope();
+        app.UseStaticFiles();
+        app.UseAuthentication();
+        app.UseAuthorization();
+        app.UseAntiforgery();
         app.MapGatewayEndpoints();
 
         return app;
@@ -35,6 +39,7 @@ public static class GatewayApplication
         builder.Services.AddSingleton<GatewayMetrics>();
         builder.Services.AddSingleton<MxAccessGrpcMapper>();
         builder.Services.AddSingleton<MxAccessGrpcRequestValidator>();
+        builder.Services.AddSingleton<IEventStreamService, EventStreamService>();
         builder.Services.AddWorkerProcessLauncher();
         builder.Services.AddGatewaySessions();
         builder.Services.AddGatewayDashboard();
@@ -55,6 +60,7 @@ public static class GatewayApplication
             .WithName("LiveHealth");
 
         endpoints.MapGrpcService<MxAccessGatewayService>();
+        endpoints.MapGatewayDashboard();
 
         return endpoints;
     }

src/MxGateway.Server/Grpc/EventStreamService.cs

@@ -0,0 +1,140 @@
+using System.Runtime.CompilerServices;
+using System.Threading.Channels;
+using Microsoft.Extensions.Options;
+using MxGateway.Contracts.Proto;
+using MxGateway.Server.Configuration;
+using MxGateway.Server.Metrics;
+using MxGateway.Server.Sessions;
+using MxGateway.Server.Workers;
+
+namespace MxGateway.Server.Grpc;
+
+public sealed class EventStreamService(
+    ISessionManager sessionManager,
+    IOptions<GatewayOptions> options,
+    MxAccessGrpcMapper mapper,
+    GatewayMetrics metrics,
+    ILogger<EventStreamService> logger) : IEventStreamService
+{
+    public async IAsyncEnumerable<MxEvent> StreamEventsAsync(
+        StreamEventsRequest request,
+        [EnumeratorCancellation] CancellationToken cancellationToken)
+    {
+        if (!sessionManager.TryGetSession(request.SessionId, out GatewaySession session))
+        {
+            throw new SessionManagerException(
+                SessionManagerErrorCode.SessionNotFound,
+                $"Session {request.SessionId} was not found.");
+        }
+
+        using IDisposable subscriber = session.AttachEventSubscriber(
+            options.Value.Sessions.AllowMultipleEventSubscribers);
+        using CancellationTokenSource streamCts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
+
+        int streamQueueDepth = 0;
+        Channel<MxEvent> eventQueue = Channel.CreateBounded<MxEvent>(
+            new BoundedChannelOptions(options.Value.Events.QueueCapacity)
+            {
+                SingleReader = true,
+                SingleWriter = true,
+                FullMode = BoundedChannelFullMode.Wait,
+                AllowSynchronousContinuations = false,
+            });
+        Task producerTask = ProduceEventsAsync(
+            session,
+            request.AfterWorkerSequence,
+            eventQueue.Writer,
+            () =>
+            {
+                int depth = Interlocked.Increment(ref streamQueueDepth);
+                metrics.SetEventQueueDepth(depth);
+            },
+            streamCts.Token);
+
+        try
+        {
+            await foreach (MxEvent mxEvent in eventQueue.Reader.ReadAllAsync(cancellationToken).ConfigureAwait(false))
+            {
+                int depth = Math.Max(0, Interlocked.Decrement(ref streamQueueDepth));
+                metrics.SetEventQueueDepth(depth);
+                yield return mxEvent;
+            }
+
+            await producerTask.ConfigureAwait(false);
+        }
+        finally
+        {
+            await streamCts.CancelAsync().ConfigureAwait(false);
+            subscriber.Dispose();
+            metrics.StreamDisconnected("Detached");
+
+            try
+            {
+                await producerTask.ConfigureAwait(false);
+            }
+            catch (OperationCanceledException) when (streamCts.IsCancellationRequested)
+            {
+            }
+            catch (Exception exception)
+            {
+                logger.LogDebug(
+                    exception,
+                    "Event stream producer stopped for session {SessionId}.",
+                    request.SessionId);
+            }
+        }
+    }
+
+    private async Task ProduceEventsAsync(
+        GatewaySession session,
+        ulong afterWorkerSequence,
+        ChannelWriter<MxEvent> writer,
+        Action eventQueued,
+        CancellationToken cancellationToken)
+    {
+        try
+        {
+            await foreach (WorkerEvent workerEvent in session
+                .ReadEventsAsync(cancellationToken)
+                .WithCancellation(cancellationToken)
+                .ConfigureAwait(false))
+            {
+                MxEvent publicEvent = mapper.MapEvent(workerEvent);
+                if (publicEvent.WorkerSequence <= afterWorkerSequence)
+                {
+                    continue;
+                }
+
+                if (!writer.TryWrite(publicEvent))
+                {
+                    string message = $"Session {session.SessionId} event stream queue overflowed.";
+                    session.MarkFaulted(message);
+                    metrics.QueueOverflow("grpc-event-stream");
+                    metrics.Fault(SessionManagerErrorCode.EventQueueOverflow.ToString());
+                    writer.TryComplete(new SessionManagerException(
+                        SessionManagerErrorCode.EventQueueOverflow,
+                        message));
+                    return;
+                }
+
+                eventQueued();
+            }
+
+            writer.TryComplete();
+        }
+        catch (OperationCanceledException) when (cancellationToken.IsCancellationRequested)
+        {
+            writer.TryComplete();
+        }
+        catch (Exception exception)
+        {
+            if (exception is WorkerClientException)
+            {
+                session.MarkFaulted(exception.Message);
+                metrics.Fault(WorkerClientErrorCode.WorkerFaulted.ToString());
+            }
+
+            writer.TryComplete(exception);
+        }
+    }
+}

src/MxGateway.Server/Grpc/IEventStreamService.cs

@@ -0,0 +1,10 @@
+using MxGateway.Contracts.Proto;
+
+namespace MxGateway.Server.Grpc;
+
+public interface IEventStreamService
+{
+    IAsyncEnumerable<MxEvent> StreamEventsAsync(
+        StreamEventsRequest request,
+        CancellationToken cancellationToken);
+}

src/MxGateway.Server/Grpc/MxAccessGatewayService.cs

@@ -12,6 +12,7 @@ public sealed class MxAccessGatewayService(
     IGatewayRequestIdentityAccessor identityAccessor,
     MxAccessGrpcRequestValidator requestValidator,
     MxAccessGrpcMapper mapper,
+    IEventStreamService eventStreamService,
     ILogger<MxAccessGatewayService> logger) : MxAccessGateway.MxAccessGatewayBase
 {
     public override async Task<OpenSessionReply> OpenSession(
@@ -102,17 +103,11 @@ public sealed class MxAccessGatewayService(
         try
         {
             requestValidator.ValidateStreamEvents(request);
-            await foreach (WorkerEvent workerEvent in sessionManager
-                .ReadEventsAsync(request.SessionId, context.CancellationToken)
+            await foreach (MxEvent publicEvent in eventStreamService
+                .StreamEventsAsync(request, context.CancellationToken)
                 .WithCancellation(context.CancellationToken)
                 .ConfigureAwait(false))
             {
-                MxEvent publicEvent = mapper.MapEvent(workerEvent);
-                if (publicEvent.WorkerSequence <= request.AfterWorkerSequence)
-                {
-                    continue;
-                }
-
                 await responseStream.WriteAsync(publicEvent).ConfigureAwait(false);
             }
         }
@@ -154,6 +149,8 @@ public sealed class MxAccessGatewayService(
         {
             SessionManagerErrorCode.SessionNotFound => StatusCode.NotFound,
             SessionManagerErrorCode.SessionNotReady => StatusCode.FailedPrecondition,
+            SessionManagerErrorCode.EventSubscriberAlreadyActive => StatusCode.ResourceExhausted,
+            SessionManagerErrorCode.EventQueueOverflow => StatusCode.ResourceExhausted,
             SessionManagerErrorCode.SessionLimitExceeded => StatusCode.ResourceExhausted,
             SessionManagerErrorCode.OpenFailed => StatusCode.Unavailable,
             SessionManagerErrorCode.CloseFailed => StatusCode.Unavailable,

src/MxGateway.Server/Sessions/GatewaySession.cs

@@ -13,6 +13,7 @@ public sealed class GatewaySession
     private DateTimeOffset _lastClientActivityAt;
     private DateTimeOffset? _leaseExpiresAt;
     private bool _closeStarted;
+    private int _activeEventSubscriberCount;
 
     public GatewaySession(
         string sessionId,
@@ -131,6 +132,17 @@ public sealed class GatewaySession
         }
     }
 
+    public int ActiveEventSubscriberCount
+    {
+        get
+        {
+            lock (_syncRoot)
+            {
+                return _activeEventSubscriberCount;
+            }
+        }
+    }
+
     public void AttachWorkerClient(IWorkerClient workerClient)
     {
         ArgumentNullException.ThrowIfNull(workerClient);
@@ -202,6 +214,29 @@ public sealed class GatewaySession
         }
     }
 
+    public IDisposable AttachEventSubscriber(bool allowMultipleSubscribers)
+    {
+        lock (_syncRoot)
+        {
+            if (_state != SessionState.Ready || _workerClient?.State != WorkerClientState.Ready)
+            {
+                throw new SessionManagerException(
+                    SessionManagerErrorCode.SessionNotReady,
+                    $"Session {SessionId} is not ready for event streaming. Current state is {_state}.");
+            }
+
+            if (!allowMultipleSubscribers && _activeEventSubscriberCount > 0)
+            {
+                throw new SessionManagerException(
+                    SessionManagerErrorCode.EventSubscriberAlreadyActive,
+                    $"Session {SessionId} already has an active event stream subscriber.");
+            }
+
+            _activeEventSubscriberCount++;
+            return new EventSubscriberLease(this);
+        }
+    }
+
     public async Task<WorkerCommandReply> InvokeAsync(
         WorkerCommand command,
         CancellationToken cancellationToken)
@@ -287,4 +322,31 @@ public sealed class GatewaySession
             return _workerClient;
         }
     }
+
+    private void DetachEventSubscriber()
+    {
+        lock (_syncRoot)
+        {
+            if (_activeEventSubscriberCount > 0)
+            {
+                _activeEventSubscriberCount--;
+            }
+        }
+    }
+
+    private sealed class EventSubscriberLease(GatewaySession session) : IDisposable
+    {
+        private bool _disposed;
+
+        public void Dispose()
+        {
+            if (_disposed)
+            {
+                return;
+            }
+
+            session.DetachEventSubscriber();
+            _disposed = true;
+        }
+    }
 }

src/MxGateway.Server/Sessions/SessionManagerErrorCode.cs

@@ -4,6 +4,8 @@ public enum SessionManagerErrorCode
 {
     SessionNotFound,
     SessionNotReady,
+    EventSubscriberAlreadyActive,
+    EventQueueOverflow,
     SessionLimitExceeded,
     OpenFailed,
     CloseFailed,

src/MxGateway.Server/Workers/WorkerClient.cs

@@ -29,6 +29,7 @@ public sealed class WorkerClient : IWorkerClient
     private WorkerClientState _state;
     private DateTimeOffset _lastHeartbeatAt;
     private int? _processId;
+    private int _eventQueueDepth;
     private Task? _readLoopTask;
     private Task? _writeLoopTask;
     private Task? _heartbeatLoopTask;
@@ -197,6 +198,8 @@ public sealed class WorkerClient : IWorkerClient
     {
         await foreach (WorkerEvent workerEvent in _events.Reader.ReadAllAsync(cancellationToken).ConfigureAwait(false))
         {
+            int queueDepth = Math.Max(0, Interlocked.Decrement(ref _eventQueueDepth));
+            _metrics?.SetEventQueueDepth(queueDepth);
             yield return workerEvent;
         }
     }
@@ -394,11 +397,6 @@ public sealed class WorkerClient : IWorkerClient
             _metrics?.EventReceived(SessionId, workerEvent.Event.Family.ToString());
         }
 
-        if (!await _events.Writer.WaitToWriteAsync(cancellationToken).ConfigureAwait(false))
-        {
-            return;
-        }
-
         if (!_events.Writer.TryWrite(workerEvent))
         {
             _metrics?.QueueOverflow("worker-events");
@@ -406,7 +404,11 @@ public sealed class WorkerClient : IWorkerClient
                 WorkerClientErrorCode.ProtocolViolation,
                 "Worker event channel rejected an event.",
                 null);
+            return;
         }
+
+        int queueDepth = Interlocked.Increment(ref _eventQueueDepth);
+        _metrics?.SetEventQueueDepth(queueDepth);
     }
 
     private void CompleteCommand(WorkerEnvelope envelope)

src/MxGateway.Server/libman.json

@@ -0,0 +1,14 @@
+{
+  "version": "1.0",
+  "defaultProvider": "cdnjs",
+  "libraries": [
+    {
+      "library": "bootstrap@5.3.3",
+      "destination": "wwwroot/lib/bootstrap/",
+      "files": [
+        "css/bootstrap.min.css",
+        "js/bootstrap.bundle.min.js"
+      ]
+    }
+  ]
+}

src/MxGateway.Server/wwwroot/css/dashboard.css

@@ -0,0 +1,138 @@
+:root {
+    --mxgw-surface: #f7f8fa;
+    --mxgw-border: #d8dee6;
+    --mxgw-ink-muted: #667085;
+    --mxgw-accent: #146c64;
+}
+
+.dashboard-body {
+    background: var(--mxgw-surface);
+    color: #1f2933;
+}
+
+.dashboard-navbar {
+    min-height: 3.5rem;
+}
+
+.dashboard-content {
+    padding: 1.25rem;
+}
+
+.dashboard-page-header {
+    align-items: center;
+    display: flex;
+    gap: 1rem;
+    justify-content: space-between;
+    margin-bottom: 1rem;
+}
+
+.dashboard-page-header h1,
+.section-heading h2 {
+    font-size: 1.35rem;
+    font-weight: 650;
+    letter-spacing: 0;
+    margin: 0;
+}
+
+.section-heading {
+    margin-bottom: .75rem;
+}
+
+.dashboard-section {
+    background: #fff;
+    border-top: 1px solid var(--mxgw-border);
+    margin-top: 1rem;
+    padding: 1rem 0 0;
+}
+
+.metric-grid {
+    display: grid;
+    gap: .75rem;
+    grid-template-columns: repeat(auto-fit, minmax(12rem, 1fr));
+}
+
+.metric-grid.compact {
+    grid-template-columns: repeat(auto-fit, minmax(10rem, 1fr));
+}
+
+.metric-card {
+    border-color: var(--mxgw-border);
+    border-radius: .375rem;
+    box-shadow: none;
+}
+
+.metric-label {
+    color: var(--mxgw-ink-muted);
+    font-size: .78rem;
+    font-weight: 650;
+    letter-spacing: 0;
+    text-transform: uppercase;
+}
+
+.metric-value {
+    color: var(--mxgw-accent);
+    font-size: 1.7rem;
+    font-weight: 700;
+    letter-spacing: 0;
+    line-height: 1.25;
+    overflow-wrap: anywhere;
+}
+
+.metric-detail {
+    color: var(--mxgw-ink-muted);
+    font-size: .85rem;
+    overflow-wrap: anywhere;
+}
+
+.dashboard-table {
+    --bs-table-bg: #fff;
+    border-color: var(--mxgw-border);
+    margin-bottom: 0;
+}
+
+.dashboard-table th {
+    color: #344054;
+    font-weight: 650;
+    white-space: nowrap;
+}
+
+.dashboard-table td {
+    max-width: 24rem;
+    overflow-wrap: anywhere;
+}
+
+.details-table th {
+    width: 14rem;
+}
+
+.empty-state {
+    background: #fff;
+    border: 1px dashed var(--mxgw-border);
+    border-radius: .375rem;
+    color: var(--mxgw-ink-muted);
+    padding: 1rem;
+}
+
+.dashboard-login {
+    max-width: 28rem;
+}
+
+.login-card {
+    border-color: var(--mxgw-border);
+    border-radius: .375rem;
+}
+
+@media (max-width: 700px) {
+    .dashboard-content {
+        padding: .75rem;
+    }
+
+    .dashboard-page-header {
+        align-items: flex-start;
+        flex-direction: column;
+    }
+
+    .details-table th {
+        width: 9rem;
+    }
+}

src/MxGateway.Tests/Gateway/Dashboard/DashboardAuthenticatorTests.cs

@@ -0,0 +1,113 @@
+using System.Security.Claims;
+using Microsoft.Extensions.Options;
+using MxGateway.Server.Configuration;
+using MxGateway.Server.Dashboard;
+using MxGateway.Server.Security.Authentication;
+using MxGateway.Server.Security.Authorization;
+
+namespace MxGateway.Tests.Gateway.Dashboard;
+
+public sealed class DashboardAuthenticatorTests
+{
+    [Fact]
+    public async Task AuthenticateAsync_AdminKey_ReturnsCookiePrincipal()
+    {
+        FakeApiKeyVerifier verifier = new(SuccessWithScopes(GatewayScopes.Admin));
+        DashboardAuthenticator authenticator = CreateAuthenticator(verifier);
+
+        DashboardAuthenticationResult result = await authenticator.AuthenticateAsync(
+            "mxgw_operator01_super-secret",
+            CancellationToken.None);
+
+        Assert.True(result.Succeeded);
+        Assert.NotNull(result.Principal);
+        Assert.Equal("operator01", result.Principal.FindFirst(ClaimTypes.NameIdentifier)?.Value);
+        Assert.Equal("Operator Key", result.Principal.FindFirst(ClaimTypes.Name)?.Value);
+        Assert.Contains(result.Principal.Claims, claim =>
+            claim.Type == DashboardAuthenticationDefaults.ScopeClaimType
+            && claim.Value == GatewayScopes.Admin);
+        Assert.Equal("Bearer mxgw_operator01_super-secret", verifier.LastAuthorizationHeader);
+    }
+
+    [Fact]
+    public async Task AuthenticateAsync_NonAdminKey_ReturnsFailureWithoutRawApiKey()
+    {
+        DashboardAuthenticator authenticator = CreateAuthenticator(new FakeApiKeyVerifier(
+            SuccessWithScopes(GatewayScopes.EventsRead)));
+
+        DashboardAuthenticationResult result = await authenticator.AuthenticateAsync(
+            "mxgw_operator01_super-secret",
+            CancellationToken.None);
+
+        Assert.False(result.Succeeded);
+        Assert.Null(result.Principal);
+        Assert.DoesNotContain("super-secret", result.FailureMessage, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public async Task AuthenticateAsync_RequireAdminScopeFalse_AllowsAuthenticatedKey()
+    {
+        DashboardAuthenticator authenticator = CreateAuthenticator(
+            new FakeApiKeyVerifier(SuccessWithScopes(GatewayScopes.EventsRead)),
+            requireAdminScope: false);
+
+        DashboardAuthenticationResult result = await authenticator.AuthenticateAsync(
+            "mxgw_operator01_secret",
+            CancellationToken.None);
+
+        Assert.True(result.Succeeded);
+        Assert.NotNull(result.Principal);
+    }
+
+    [Fact]
+    public async Task AuthenticateAsync_InvalidKey_ReturnsGenericFailure()
+    {
+        DashboardAuthenticator authenticator = CreateAuthenticator(new FakeApiKeyVerifier(
+            ApiKeyVerificationResult.Fail(ApiKeyVerificationFailure.SecretMismatch)));
+
+        DashboardAuthenticationResult result = await authenticator.AuthenticateAsync(
+            "mxgw_operator01_super-secret",
+            CancellationToken.None);
+
+        Assert.False(result.Succeeded);
+        Assert.DoesNotContain("super-secret", result.FailureMessage, StringComparison.Ordinal);
+    }
+
+    private static DashboardAuthenticator CreateAuthenticator(
+        IApiKeyVerifier verifier,
+        bool requireAdminScope = true)
+    {
+        return new DashboardAuthenticator(
+            verifier,
+            Options.Create(new GatewayOptions
+            {
+                Dashboard = new DashboardOptions
+                {
+                    RequireAdminScope = requireAdminScope
+                }
+            }));
+    }
+
+    private static ApiKeyVerificationResult SuccessWithScopes(params string[] scopes)
+    {
+        return ApiKeyVerificationResult.Success(new ApiKeyIdentity(
+            KeyId: "operator01",
+            KeyPrefix: "mxgw_operator01",
+            DisplayName: "Operator Key",
+            Scopes: new HashSet<string>(scopes, StringComparer.Ordinal)));
+    }
+
+    private sealed class FakeApiKeyVerifier(ApiKeyVerificationResult result) : IApiKeyVerifier
+    {
+        public string? LastAuthorizationHeader { get; private set; }
+
+        public Task<ApiKeyVerificationResult> VerifyAsync(
+            string? authorizationHeader,
+            CancellationToken cancellationToken)
+        {
+            LastAuthorizationHeader = authorizationHeader;
+
+            return Task.FromResult(result);
+        }
+    }
+}

src/MxGateway.Tests/Gateway/Dashboard/DashboardAuthorizationHandlerTests.cs

@@ -0,0 +1,91 @@
+using System.Net;
+using System.Security.Claims;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Http;
+using Microsoft.Extensions.Options;
+using MxGateway.Server.Configuration;
+using MxGateway.Server.Dashboard;
+using MxGateway.Server.Security.Authorization;
+
+namespace MxGateway.Tests.Gateway.Dashboard;
+
+public sealed class DashboardAuthorizationHandlerTests
+{
+    [Fact]
+    public async Task HandleAsync_UnauthenticatedRemoteRequest_DoesNotSucceed()
+    {
+        AuthorizationHandlerContext context = await AuthorizeAsync(
+            new ClaimsPrincipal(new ClaimsIdentity()),
+            IPAddress.Parse("10.0.0.5"),
+            allowAnonymousLocalhost: false);
+
+        Assert.False(context.HasSucceeded);
+    }
+
+    [Fact]
+    public async Task HandleAsync_AnonymousLocalhostAllowed_Succeeds()
+    {
+        AuthorizationHandlerContext context = await AuthorizeAsync(
+            new ClaimsPrincipal(new ClaimsIdentity()),
+            IPAddress.Loopback,
+            allowAnonymousLocalhost: true);
+
+        Assert.True(context.HasSucceeded);
+    }
+
+    [Fact]
+    public async Task HandleAsync_AuthenticatedWithoutAdminScope_DoesNotSucceed()
+    {
+        AuthorizationHandlerContext context = await AuthorizeAsync(
+            CreatePrincipal(GatewayScopes.EventsRead),
+            IPAddress.Loopback,
+            allowAnonymousLocalhost: false);
+
+        Assert.False(context.HasSucceeded);
+    }
+
+    [Fact]
+    public async Task HandleAsync_AuthenticatedWithAdminScope_Succeeds()
+    {
+        AuthorizationHandlerContext context = await AuthorizeAsync(
+            CreatePrincipal(GatewayScopes.Admin),
+            IPAddress.Parse("10.0.0.5"),
+            allowAnonymousLocalhost: false);
+
+        Assert.True(context.HasSucceeded);
+    }
+
+    private static async Task<AuthorizationHandlerContext> AuthorizeAsync(
+        ClaimsPrincipal principal,
+        IPAddress remoteAddress,
+        bool allowAnonymousLocalhost)
+    {
+        DashboardAuthorizationRequirement requirement = new();
+        DefaultHttpContext httpContext = new();
+        httpContext.Connection.RemoteIpAddress = remoteAddress;
+        DashboardAuthorizationHandler handler = new(
+            new HttpContextAccessor { HttpContext = httpContext },
+            Options.Create(new GatewayOptions
+            {
+                Dashboard = new DashboardOptions
+                {
+                    AllowAnonymousLocalhost = allowAnonymousLocalhost,
+                    RequireAdminScope = true
+                }
+            }));
+        AuthorizationHandlerContext context = new([requirement], principal, httpContext);
+
+        await handler.HandleAsync(context);
+
+        return context;
+    }
+
+    private static ClaimsPrincipal CreatePrincipal(string scope)
+    {
+        ClaimsIdentity identity = new(
+            [new Claim(DashboardAuthenticationDefaults.ScopeClaimType, scope)],
+            DashboardAuthenticationDefaults.AuthenticationScheme);
+
+        return new ClaimsPrincipal(identity);
+    }
+}

src/MxGateway.Tests/Gateway/Dashboard/DashboardCookieOptionsTests.cs

@@ -0,0 +1,32 @@
+using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Authentication.Cookies;
+using Microsoft.AspNetCore.Http;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Options;
+using MxGateway.Server;
+using MxGateway.Server.Dashboard;
+
+namespace MxGateway.Tests.Gateway.Dashboard;
+
+public sealed class DashboardCookieOptionsTests
+{
+    [Fact]
+    public void Build_ConfiguresSecureDashboardCookie()
+    {
+        WebApplication app = GatewayApplication.Build([]);
+        IOptionsMonitor<CookieAuthenticationOptions> optionsMonitor = app.Services
+            .GetRequiredService<IOptionsMonitor<CookieAuthenticationOptions>>();
+
+        CookieAuthenticationOptions options = optionsMonitor.Get(
+            DashboardAuthenticationDefaults.AuthenticationScheme);
+
+        Assert.Equal(DashboardAuthenticationDefaults.CookieName, options.Cookie.Name);
+        Assert.True(options.Cookie.HttpOnly);
+        Assert.Equal(CookieSecurePolicy.Always, options.Cookie.SecurePolicy);
+        Assert.Equal(SameSiteMode.Strict, options.Cookie.SameSite);
+        Assert.Equal("/", options.Cookie.Path);
+        Assert.Equal("/dashboard/login", options.LoginPath);
+        Assert.Equal("/dashboard/logout", options.LogoutPath);
+        Assert.Equal("/dashboard/denied", options.AccessDeniedPath);
+    }
+}

src/MxGateway.Tests/Gateway/GatewayApplicationTests.cs

@@ -33,6 +33,37 @@ public sealed class GatewayApplicationTests
         Assert.NotNull(metrics);
     }
 
+    [Fact]
+    public void Build_WhenDashboardEnabled_MapsBlazorDashboardAndAuthEndpoints()
+    {
+        WebApplication app = GatewayApplication.Build([]);
+        IReadOnlyList<RouteEndpoint> endpoints = GetRouteEndpoints(app);
+
+        Assert.Contains(endpoints, endpoint => endpoint.RoutePattern.RawText == "/dashboard/");
+        Assert.Contains(endpoints, endpoint => endpoint.RoutePattern.RawText == "/dashboard/sessions");
+        Assert.Contains(endpoints, endpoint => endpoint.RoutePattern.RawText == "/dashboard/workers");
+        Assert.Contains(endpoints, endpoint => endpoint.RoutePattern.RawText == "/dashboard/events");
+        Assert.Contains(endpoints, endpoint => endpoint.RoutePattern.RawText == "/dashboard/settings");
+        Assert.Contains(endpoints, endpoint =>
+            endpoint.Metadata.GetMetadata<IEndpointNameMetadata>()?.EndpointName == "DashboardLogin");
+        Assert.Contains(endpoints, endpoint =>
+            endpoint.Metadata.GetMetadata<IEndpointNameMetadata>()?.EndpointName == "DashboardLogout");
+    }
+
+    [Fact]
+    public void Build_WhenDashboardDisabled_DoesNotMapDashboardRoutes()
+    {
+        WebApplication app = GatewayApplication.Build(["--MxGateway:Dashboard:Enabled=false"]);
+        IReadOnlyList<RouteEndpoint> endpoints = GetRouteEndpoints(app);
+
+        Assert.DoesNotContain(endpoints, endpoint =>
+            endpoint.RoutePattern.RawText?.StartsWith("/dashboard", StringComparison.Ordinal) == true);
+        Assert.DoesNotContain(endpoints, endpoint =>
+            endpoint.Metadata.GetMetadata<IEndpointNameMetadata>()?.EndpointName?.StartsWith(
+                "Dashboard",
+                StringComparison.Ordinal) == true);
+    }
+
     [Theory]
     [InlineData(
         "MxGateway:Worker:ExecutablePath",
@@ -65,4 +96,12 @@ public sealed class GatewayApplicationTests
             exception.Failures,
             failure => failure.Contains(expectedFailure, StringComparison.Ordinal));
     }
+
+    private static IReadOnlyList<RouteEndpoint> GetRouteEndpoints(WebApplication app)
+    {
+        return ((IEndpointRouteBuilder)app).DataSources
+            .SelectMany(dataSource => dataSource.Endpoints)
+            .OfType<RouteEndpoint>()
+            .ToArray();
+    }
 }

src/MxGateway.Tests/Gateway/GatewayEndToEndFakeWorkerSmokeTests.cs

@@ -0,0 +1,439 @@
+using System.Collections.Concurrent;
+using Google.Protobuf.WellKnownTypes;
+using Grpc.Core;
+using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Extensions.Options;
+using MxGateway.Contracts;
+using MxGateway.Contracts.Proto;
+using MxGateway.Server.Configuration;
+using MxGateway.Server.Grpc;
+using MxGateway.Server.Metrics;
+using MxGateway.Server.Security.Authorization;
+using MxGateway.Server.Sessions;
+using MxGateway.Server.Workers;
+using MxGateway.Tests.Gateway.Workers.Fakes;
+
+namespace MxGateway.Tests.Gateway;
+
+public sealed class GatewayEndToEndFakeWorkerSmokeTests
+{
+    private static readonly TimeSpan TestTimeout = TimeSpan.FromSeconds(5);
+    private const int ServerHandle = 1001;
+    private const int ItemHandle = 2002;
+
+    [Fact]
+    public async Task GatewayService_WithFakeWorker_CompletesSessionCommandEventAndClosePath()
+    {
+        ScriptedFakeWorkerProcessLauncher launcher = new();
+        await using GatewayServiceFixture fixture = new(launcher);
+
+        OpenSessionReply openReply = await fixture.Service.OpenSession(
+            new OpenSessionRequest
+            {
+                ClientSessionName = "fake-worker-e2e",
+                ClientCorrelationId = "open-correlation",
+                CommandTimeout = Duration.FromTimeSpan(TestTimeout),
+            },
+            new TestServerCallContext());
+
+        RecordingServerStreamWriter<MxEvent> eventWriter = new();
+        Task streamTask = fixture.Service.StreamEvents(
+            new StreamEventsRequest { SessionId = openReply.SessionId },
+            eventWriter,
+            new TestServerCallContext());
+
+        MxCommandReply registerReply = await fixture.Service.Invoke(
+            CreateRegisterRequest(openReply.SessionId),
+            new TestServerCallContext());
+        MxCommandReply addItemReply = await fixture.Service.Invoke(
+            CreateAddItemRequest(openReply.SessionId, registerReply.Register.ServerHandle),
+            new TestServerCallContext());
+        MxCommandReply adviseReply = await fixture.Service.Invoke(
+            CreateAdviseRequest(openReply.SessionId, registerReply.Register.ServerHandle, addItemReply.AddItem.ItemHandle),
+            new TestServerCallContext());
+
+        MxEvent dataChange = await eventWriter.WaitForFirstMessageAsync(TestTimeout);
+
+        CloseSessionReply closeReply = await fixture.Service.CloseSession(
+            new CloseSessionRequest
+            {
+                SessionId = openReply.SessionId,
+                ClientCorrelationId = "close-correlation",
+            },
+            new TestServerCallContext());
+
+        await streamTask.WaitAsync(TestTimeout);
+        await launcher.WorkerTask.WaitAsync(TestTimeout);
+
+        Assert.Equal(ProtocolStatusCode.Ok, openReply.ProtocolStatus.Code);
+        Assert.Equal(GatewayContractInfo.DefaultBackendName, openReply.BackendName);
+        Assert.Equal(ScriptedFakeWorkerProcessLauncher.ProcessId, openReply.WorkerProcessId);
+        Assert.Equal(ProtocolStatusCode.Ok, registerReply.ProtocolStatus.Code);
+        Assert.Equal(ServerHandle, registerReply.Register.ServerHandle);
+        Assert.Equal(ProtocolStatusCode.Ok, addItemReply.ProtocolStatus.Code);
+        Assert.Equal(ItemHandle, addItemReply.AddItem.ItemHandle);
+        Assert.Equal(ProtocolStatusCode.Ok, adviseReply.ProtocolStatus.Code);
+        Assert.Equal(MxEventFamily.OnDataChange, dataChange.Family);
+        Assert.Equal(openReply.SessionId, dataChange.SessionId);
+        Assert.Equal(ServerHandle, dataChange.ServerHandle);
+        Assert.Equal(ItemHandle, dataChange.ItemHandle);
+        Assert.Equal("scripted-value", dataChange.Value.StringValue);
+        Assert.Equal(ProtocolStatusCode.Ok, closeReply.ProtocolStatus.Code);
+        Assert.Equal(SessionState.Closed, closeReply.FinalState);
+        Assert.True(launcher.Process.HasExited);
+        Assert.Equal(
+            [MxCommandKind.Register, MxCommandKind.AddItem, MxCommandKind.Advise],
+            launcher.CommandKinds);
+    }
+
+    private static MxCommandRequest CreateRegisterRequest(string sessionId)
+    {
+        return new MxCommandRequest
+        {
+            SessionId = sessionId,
+            ClientCorrelationId = "register-correlation",
+            Command = new MxCommand
+            {
+                Kind = MxCommandKind.Register,
+                Register = new RegisterCommand { ClientName = "fake-worker-e2e-client" },
+            },
+        };
+    }
+
+    private static MxCommandRequest CreateAddItemRequest(
+        string sessionId,
+        int serverHandle)
+    {
+        return new MxCommandRequest
+        {
+            SessionId = sessionId,
+            ClientCorrelationId = "add-item-correlation",
+            Command = new MxCommand
+            {
+                Kind = MxCommandKind.AddItem,
+                AddItem = new AddItemCommand
+                {
+                    ServerHandle = serverHandle,
+                    ItemDefinition = "Galaxy.Tag.Value",
+                },
+            },
+        };
+    }
+
+    private static MxCommandRequest CreateAdviseRequest(
+        string sessionId,
+        int serverHandle,
+        int itemHandle)
+    {
+        return new MxCommandRequest
+        {
+            SessionId = sessionId,
+            ClientCorrelationId = "advise-correlation",
+            Command = new MxCommand
+            {
+                Kind = MxCommandKind.Advise,
+                Advise = new AdviseCommand
+                {
+                    ServerHandle = serverHandle,
+                    ItemHandle = itemHandle,
+                },
+            },
+        };
+    }
+
+    private sealed class GatewayServiceFixture : IAsyncDisposable
+    {
+        private readonly GatewayMetrics _metrics = new();
+        private readonly SessionRegistry _registry = new();
+
+        public GatewayServiceFixture(IWorkerProcessLauncher launcher)
+        {
+            IOptions<GatewayOptions> options = Options.Create(CreateOptions());
+            SessionWorkerClientFactory workerClientFactory = new(
+                launcher,
+                options,
+                _metrics,
+                NullLoggerFactory.Instance);
+            SessionManager sessionManager = new(
+                _registry,
+                workerClientFactory,
+                options,
+                _metrics,
+                logger: NullLogger<SessionManager>.Instance);
+            MxAccessGrpcMapper mapper = new();
+            EventStreamService eventStreamService = new(
+                sessionManager,
+                options,
+                mapper,
+                _metrics,
+                NullLogger<EventStreamService>.Instance);
+
+            Service = new MxAccessGatewayService(
+                sessionManager,
+                new GatewayRequestIdentityAccessor(),
+                new MxAccessGrpcRequestValidator(),
+                mapper,
+                eventStreamService,
+                NullLogger<MxAccessGatewayService>.Instance);
+        }
+
+        public MxAccessGatewayService Service { get; }
+
+        public async ValueTask DisposeAsync()
+        {
+            foreach (GatewaySession session in _registry.Snapshot())
+            {
+                await session.DisposeAsync();
+            }
+
+            _metrics.Dispose();
+        }
+
+        private static GatewayOptions CreateOptions()
+        {
+            return new GatewayOptions
+            {
+                Worker = new WorkerOptions
+                {
+                    StartupTimeoutSeconds = 5,
+                    ShutdownTimeoutSeconds = 5,
+                    HeartbeatIntervalSeconds = 30,
+                    HeartbeatGraceSeconds = 30,
+                    MaxMessageBytes = WorkerFrameProtocolOptions.DefaultMaxMessageBytes,
+                },
+                Sessions = new SessionOptions
+                {
+                    DefaultCommandTimeoutSeconds = 5,
+                    MaxSessions = 4,
+                },
+                Events = new EventOptions
+                {
+                    QueueCapacity = 16,
+                },
+            };
+        }
+    }
+
+    private sealed class ScriptedFakeWorkerProcessLauncher : IWorkerProcessLauncher
+    {
+        public const int ProcessId = 4680;
+        private readonly ConcurrentQueue<MxCommandKind> _commandKinds = new();
+
+        public FakeWorkerProcess Process { get; } = new(ProcessId);
+
+        public IReadOnlyCollection<MxCommandKind> CommandKinds => _commandKinds.ToArray();
+
+        public Task WorkerTask { get; private set; } = Task.CompletedTask;
+
+        public Task<WorkerProcessHandle> LaunchAsync(
+            WorkerProcessLaunchRequest request,
+            CancellationToken cancellationToken = default)
+        {
+            WorkerTask = RunWorkerAsync(request, cancellationToken);
+
+            return Task.FromResult(new WorkerProcessHandle(
+                Process,
+                new WorkerProcessCommandLine("fake-worker.exe", []),
+                DateTimeOffset.UtcNow));
+        }
+
+        private async Task RunWorkerAsync(
+            WorkerProcessLaunchRequest request,
+            CancellationToken cancellationToken)
+        {
+            await using FakeWorkerHarness harness = await FakeWorkerHarness.ConnectToGatewayPipeAsync(
+                request.SessionId,
+                request.Nonce,
+                request.PipeName,
+                request.ProtocolVersion,
+                cancellationToken: cancellationToken).ConfigureAwait(false);
+            await harness.CompleteStartupAsync(ProcessId, cancellationToken: cancellationToken).ConfigureAwait(false);
+
+            while (!cancellationToken.IsCancellationRequested)
+            {
+                WorkerEnvelope envelope = await harness.ReadGatewayEnvelopeAsync(cancellationToken).ConfigureAwait(false);
+                if (envelope.BodyCase == WorkerEnvelope.BodyOneofCase.WorkerCommand)
+                {
+                    await ReplyToCommandAsync(harness, envelope, cancellationToken).ConfigureAwait(false);
+                    continue;
+                }
+
+                if (envelope.BodyCase == WorkerEnvelope.BodyOneofCase.WorkerShutdown)
+                {
+                    await harness.SendShutdownAckAsync(cancellationToken: cancellationToken).ConfigureAwait(false);
+                    Process.MarkExited(0);
+                    return;
+                }
+
+                throw new InvalidOperationException($"Unexpected gateway envelope {envelope.BodyCase}.");
+            }
+        }
+
+        private async Task ReplyToCommandAsync(
+            FakeWorkerHarness harness,
+            WorkerEnvelope commandEnvelope,
+            CancellationToken cancellationToken)
+        {
+            MxCommand command = commandEnvelope.WorkerCommand.Command;
+            _commandKinds.Enqueue(command.Kind);
+
+            await harness.ReplyToCommandAsync(
+                commandEnvelope,
+                configureReply: reply => ConfigureReply(reply, command.Kind),
+                cancellationToken: cancellationToken).ConfigureAwait(false);
+
+            if (command.Kind == MxCommandKind.Advise)
+            {
+                await harness.EmitEventAsync(
+                    MxEventFamily.OnDataChange,
+                    cancellationToken,
+                    mxEvent =>
+                    {
+                        mxEvent.ServerHandle = command.Advise.ServerHandle;
+                        mxEvent.ItemHandle = command.Advise.ItemHandle;
+                        mxEvent.Quality = 192;
+                        mxEvent.Value = new MxValue
+                        {
+                            DataType = MxDataType.String,
+                            StringValue = "scripted-value",
+                        };
+                        mxEvent.OnDataChange = new OnDataChangeEvent();
+                    }).ConfigureAwait(false);
+            }
+        }
+
+        private static void ConfigureReply(
+            MxCommandReply reply,
+            MxCommandKind kind)
+        {
+            switch (kind)
+            {
+                case MxCommandKind.Register:
+                    reply.Register = new RegisterReply { ServerHandle = ServerHandle };
+                    break;
+                case MxCommandKind.AddItem:
+                    reply.AddItem = new AddItemReply { ItemHandle = ItemHandle };
+                    break;
+            }
+        }
+    }
+
+    private sealed class FakeWorkerProcess(int processId) : IWorkerProcess
+    {
+        public int Id { get; } = processId;
+
+        public bool HasExited { get; private set; }
+
+        public int? ExitCode { get; private set; }
+
+        public ValueTask WaitForExitAsync(CancellationToken cancellationToken)
+        {
+            HasExited = true;
+            ExitCode ??= 0;
+            return ValueTask.CompletedTask;
+        }
+
+        public void Kill(bool entireProcessTree)
+        {
+            MarkExited(-1);
+        }
+
+        public void Dispose()
+        {
+        }
+
+        public void MarkExited(int exitCode)
+        {
+            HasExited = true;
+            ExitCode = exitCode;
+        }
+    }
+
+    private sealed class RecordingServerStreamWriter<T> : IServerStreamWriter<T>
+    {
+        private readonly object _syncRoot = new();
+        private readonly TaskCompletionSource<T> _firstMessage = new(TaskCreationOptions.RunContinuationsAsynchronously);
+        private readonly List<T> _messages = [];
+
+        public IReadOnlyList<T> Messages
+        {
+            get
+            {
+                lock (_syncRoot)
+                {
+                    return _messages.ToArray();
+                }
+            }
+        }
+
+        public WriteOptions? WriteOptions { get; set; }
+
+        public Task WriteAsync(T message)
+        {
+            lock (_syncRoot)
+            {
+                _messages.Add(message);
+            }
+
+            _firstMessage.TrySetResult(message);
+            return Task.CompletedTask;
+        }
+
+        public async Task<T> WaitForFirstMessageAsync(TimeSpan timeout)
+        {
+            return await _firstMessage.Task.WaitAsync(timeout).ConfigureAwait(false);
+        }
+    }
+
+    private sealed class TestServerCallContext(CancellationToken cancellationToken = default) : ServerCallContext
+    {
+        private readonly Metadata _requestHeaders = [];
+        private readonly Metadata _responseTrailers = [];
+        private readonly Dictionary<object, object> _userState = [];
+        private Status _status;
+        private WriteOptions? _writeOptions;
+
+        protected override string MethodCore => "/mxaccess_gateway.v1.MxAccessGateway/Test";
+
+        protected override string HostCore => "localhost";
+
+        protected override string PeerCore => "ipv4:127.0.0.1:5000";
+
+        protected override DateTime DeadlineCore => DateTime.UtcNow.AddMinutes(1);
+
+        protected override Metadata RequestHeadersCore => _requestHeaders;
+
+        protected override CancellationToken CancellationTokenCore => cancellationToken;
+
+        protected override Metadata ResponseTrailersCore => _responseTrailers;
+
+        protected override Status StatusCore
+        {
+            get => _status;
+            set => _status = value;
+        }
+
+        protected override WriteOptions? WriteOptionsCore
+        {
+            get => _writeOptions;
+            set => _writeOptions = value;
+        }
+
+        protected override AuthContext AuthContextCore { get; } = new(
+            string.Empty,
+            new Dictionary<string, List<AuthProperty>>(StringComparer.Ordinal));
+
+        protected override IDictionary<object, object> UserStateCore => _userState;
+
+        protected override Task WriteResponseHeadersAsyncCore(Metadata responseHeaders)
+        {
+            return Task.CompletedTask;
+        }
+
+        protected override ContextPropagationToken CreatePropagationTokenCore(
+            ContextPropagationOptions? options)
+        {
+            throw new NotSupportedException();
+        }
+    }
+}

src/MxGateway.Tests/Gateway/Grpc/EventStreamServiceTests.cs

@@ -0,0 +1,383 @@
+using System.Runtime.CompilerServices;
+using Grpc.Core;
+using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Extensions.Options;
+using MxGateway.Contracts;
+using MxGateway.Contracts.Proto;
+using MxGateway.Server.Configuration;
+using MxGateway.Server.Grpc;
+using MxGateway.Server.Metrics;
+using MxGateway.Server.Sessions;
+using MxGateway.Server.Workers;
+
+namespace MxGateway.Tests.Gateway.Grpc;
+
+public sealed class EventStreamServiceTests
+{
+    private static readonly TimeSpan TestTimeout = TimeSpan.FromSeconds(5);
+
+    [Fact]
+    public async Task StreamEventsAsync_YieldsEventsInWorkerOrder()
+    {
+        FakeWorkerClient workerClient = new();
+        GatewaySession session = CreateReadySession(workerClient);
+        FakeSessionManager sessionManager = new(session);
+        using GatewayMetrics metrics = new();
+        EventStreamService service = CreateService(sessionManager, metrics: metrics);
+        workerClient.Events.Add(CreateWorkerEvent(sequence: 10, MxEventFamily.OnDataChange));
+        workerClient.Events.Add(CreateWorkerEvent(sequence: 11, MxEventFamily.OnWriteComplete));
+        workerClient.CompleteAfterConfiguredEvents = true;
+
+        List<MxEvent> events = await CollectEventsAsync(service, session.SessionId);
+
+        Assert.Equal([10UL, 11UL], events.Select(mxEvent => mxEvent.WorkerSequence).ToArray());
+        Assert.Equal(MxEventFamily.OnDataChange, events[0].Family);
+        Assert.Equal(MxEventFamily.OnWriteComplete, events[1].Family);
+        Assert.Equal(1, metrics.GetSnapshot().StreamDisconnects);
+    }
+
+    [Fact]
+    public async Task StreamEventsAsync_WhenSecondSubscriberStarts_RejectsClearly()
+    {
+        FakeWorkerClient workerClient = new();
+        GatewaySession session = CreateReadySession(workerClient);
+        EventStreamService service = CreateService(new FakeSessionManager(session));
+        using CancellationTokenSource firstSubscriberCancellation = new();
+        await using IAsyncEnumerator<MxEvent> firstSubscriber = service
+            .StreamEventsAsync(CreateRequest(session.SessionId), firstSubscriberCancellation.Token)
+            .GetAsyncEnumerator(firstSubscriberCancellation.Token);
+        Task<bool> firstMoveTask = firstSubscriber.MoveNextAsync().AsTask();
+
+        await WaitUntilAsync(() => session.ActiveEventSubscriberCount == 1);
+        await using IAsyncEnumerator<MxEvent> secondSubscriber = service
+            .StreamEventsAsync(CreateRequest(session.SessionId), CancellationToken.None)
+            .GetAsyncEnumerator();
+
+        SessionManagerException exception = await Assert.ThrowsAsync<SessionManagerException>(
+            async () => await secondSubscriber.MoveNextAsync().AsTask().WaitAsync(TestTimeout));
+
+        Assert.Equal(SessionManagerErrorCode.EventSubscriberAlreadyActive, exception.ErrorCode);
+        await firstSubscriberCancellation.CancelAsync();
+        await Assert.ThrowsAnyAsync<OperationCanceledException>(
+            async () => await firstMoveTask.WaitAsync(TestTimeout));
+        await firstSubscriber.DisposeAsync();
+        await WaitUntilAsync(() => session.ActiveEventSubscriberCount == 0);
+    }
+
+    [Fact]
+    public async Task StreamEventsAsync_WhenCanceled_DetachesSubscriber()
+    {
+        FakeWorkerClient workerClient = new();
+        GatewaySession session = CreateReadySession(workerClient);
+        EventStreamService service = CreateService(new FakeSessionManager(session));
+        using CancellationTokenSource cancellationTokenSource = new();
+        await using IAsyncEnumerator<MxEvent> subscriber = service
+            .StreamEventsAsync(CreateRequest(session.SessionId), cancellationTokenSource.Token)
+            .GetAsyncEnumerator(cancellationTokenSource.Token);
+        Task<bool> moveTask = subscriber.MoveNextAsync().AsTask();
+
+        await WaitUntilAsync(() => session.ActiveEventSubscriberCount == 1);
+        await cancellationTokenSource.CancelAsync();
+        await Assert.ThrowsAnyAsync<OperationCanceledException>(
+            async () => await moveTask.WaitAsync(TestTimeout));
+        await subscriber.DisposeAsync();
+
+        await WaitUntilAsync(() => session.ActiveEventSubscriberCount == 0);
+    }
+
+    [Fact]
+    public async Task StreamEventsAsync_WhenStreamQueueOverflows_FaultsSessionAndReportsOverflow()
+    {
+        FakeWorkerClient workerClient = new();
+        GatewaySession session = CreateReadySession(workerClient);
+        using GatewayMetrics metrics = new();
+        EventStreamService service = CreateService(
+            new FakeSessionManager(session),
+            metrics,
+            queueCapacity: 1);
+        workerClient.Events.Add(CreateWorkerEvent(sequence: 1, MxEventFamily.OnDataChange));
+        workerClient.Events.Add(CreateWorkerEvent(sequence: 2, MxEventFamily.OnDataChange));
+        workerClient.Events.Add(CreateWorkerEvent(sequence: 3, MxEventFamily.OnDataChange));
+        workerClient.CompleteAfterConfiguredEvents = true;
+        await using IAsyncEnumerator<MxEvent> subscriber = service
+            .StreamEventsAsync(CreateRequest(session.SessionId), CancellationToken.None)
+            .GetAsyncEnumerator();
+
+        Assert.True(await subscriber.MoveNextAsync().AsTask().WaitAsync(TestTimeout));
+        await WaitUntilAsync(() => session.State == SessionState.Faulted);
+        SessionManagerException exception = await Assert.ThrowsAsync<SessionManagerException>(
+            async () => await subscriber.MoveNextAsync().AsTask().WaitAsync(TestTimeout));
+
+        Assert.Equal(SessionManagerErrorCode.EventQueueOverflow, exception.ErrorCode);
+        Assert.Equal(SessionState.Faulted, session.State);
+        Assert.Equal(1, metrics.GetSnapshot().QueueOverflows);
+        Assert.Equal(1, metrics.GetSnapshot().Faults);
+    }
+
+    [Fact]
+    public async Task StreamEventsAsync_DoesNotSynthesizeOperationComplete()
+    {
+        FakeWorkerClient workerClient = new();
+        GatewaySession session = CreateReadySession(workerClient);
+        EventStreamService service = CreateService(new FakeSessionManager(session));
+        workerClient.Events.Add(CreateWorkerEvent(sequence: 10, MxEventFamily.OnWriteComplete));
+        workerClient.CompleteAfterConfiguredEvents = true;
+
+        List<MxEvent> events = await CollectEventsAsync(service, session.SessionId);
+
+        MxEvent mxEvent = Assert.Single(events);
+        Assert.Equal(MxEventFamily.OnWriteComplete, mxEvent.Family);
+        Assert.DoesNotContain(events, candidate => candidate.Family == MxEventFamily.OperationComplete);
+    }
+
+    [Fact]
+    public async Task StreamEventsAsync_WhenWorkerEventStreamFaults_PropagatesTerminalFault()
+    {
+        FakeWorkerClient workerClient = new()
+        {
+            TerminalException = new WorkerClientException(
+                WorkerClientErrorCode.WorkerFaulted,
+                "worker terminal fault"),
+        };
+        GatewaySession session = CreateReadySession(workerClient);
+        using GatewayMetrics metrics = new();
+        EventStreamService service = CreateService(new FakeSessionManager(session), metrics);
+        await using IAsyncEnumerator<MxEvent> subscriber = service
+            .StreamEventsAsync(CreateRequest(session.SessionId), CancellationToken.None)
+            .GetAsyncEnumerator();
+
+        WorkerClientException exception = await Assert.ThrowsAsync<WorkerClientException>(
+            async () => await subscriber.MoveNextAsync().AsTask().WaitAsync(TestTimeout));
+
+        Assert.Equal(WorkerClientErrorCode.WorkerFaulted, exception.ErrorCode);
+        Assert.Equal(SessionState.Faulted, session.State);
+        Assert.Equal(1, metrics.GetSnapshot().Faults);
+    }
+
+    private static EventStreamService CreateService(
+        FakeSessionManager sessionManager,
+        GatewayMetrics? metrics = null,
+        int queueCapacity = 8)
+    {
+        return new EventStreamService(
+            sessionManager,
+            Options.Create(new GatewayOptions
+            {
+                Events = new EventOptions
+                {
+                    QueueCapacity = queueCapacity,
+                },
+            }),
+            new MxAccessGrpcMapper(),
+            metrics ?? new GatewayMetrics(),
+            NullLogger<EventStreamService>.Instance);
+    }
+
+    private static async Task<List<MxEvent>> CollectEventsAsync(
+        EventStreamService service,
+        string sessionId)
+    {
+        List<MxEvent> events = [];
+        await foreach (MxEvent mxEvent in service
+            .StreamEventsAsync(CreateRequest(sessionId), CancellationToken.None)
+            .WithCancellation(CancellationToken.None))
+        {
+            events.Add(mxEvent);
+        }
+
+        return events;
+    }
+
+    private static StreamEventsRequest CreateRequest(string sessionId)
+    {
+        return new StreamEventsRequest
+        {
+            SessionId = sessionId,
+        };
+    }
+
+    private static GatewaySession CreateReadySession(FakeWorkerClient workerClient)
+    {
+        GatewaySession session = new(
+            "session-events",
+            GatewayContractInfo.DefaultBackendName,
+            "pipe",
+            "nonce",
+            "client",
+            "client-session",
+            "client-correlation",
+            TimeSpan.FromSeconds(30),
+            TimeSpan.FromSeconds(30),
+            TimeSpan.FromSeconds(10),
+            DateTimeOffset.UtcNow);
+        session.AttachWorkerClient(workerClient);
+        session.MarkReady();
+
+        return session;
+    }
+
+    private static WorkerEvent CreateWorkerEvent(
+        ulong sequence,
+        MxEventFamily family)
+    {
+        MxEvent mxEvent = new()
+        {
+            SessionId = "session-events",
+            Family = family,
+            WorkerSequence = sequence,
+        };
+
+        switch (family)
+        {
+            case MxEventFamily.OnDataChange:
+                mxEvent.OnDataChange = new OnDataChangeEvent();
+                break;
+            case MxEventFamily.OnWriteComplete:
+                mxEvent.OnWriteComplete = new OnWriteCompleteEvent();
+                break;
+            case MxEventFamily.OperationComplete:
+                mxEvent.OperationComplete = new OperationCompleteEvent();
+                break;
+            case MxEventFamily.OnBufferedDataChange:
+                mxEvent.OnBufferedDataChange = new OnBufferedDataChangeEvent();
+                break;
+        }
+
+        return new WorkerEvent
+        {
+            Event = mxEvent,
+        };
+    }
+
+    private static async Task WaitUntilAsync(Func<bool> predicate)
+    {
+        using CancellationTokenSource cancellationTokenSource = new(TestTimeout);
+        while (!predicate())
+        {
+            await Task.Delay(TimeSpan.FromMilliseconds(10), cancellationTokenSource.Token);
+        }
+    }
+
+    private sealed class FakeSessionManager(GatewaySession session) : ISessionManager
+    {
+        public Task<GatewaySession> OpenSessionAsync(
+            SessionOpenRequest request,
+            string? clientIdentity,
+            CancellationToken cancellationToken)
+        {
+            return Task.FromResult(session);
+        }
+
+        public bool TryGetSession(
+            string sessionId,
+            out GatewaySession gatewaySession)
+        {
+            gatewaySession = session;
+            return string.Equals(sessionId, session.SessionId, StringComparison.Ordinal);
+        }
+
+        public Task<WorkerCommandReply> InvokeAsync(
+            string sessionId,
+            WorkerCommand command,
+            CancellationToken cancellationToken)
+        {
+            return Task.FromResult(new WorkerCommandReply());
+        }
+
+        public IAsyncEnumerable<WorkerEvent> ReadEventsAsync(
+            string sessionId,
+            CancellationToken cancellationToken)
+        {
+            return session.ReadEventsAsync(cancellationToken);
+        }
+
+        public Task<SessionCloseResult> CloseSessionAsync(
+            string sessionId,
+            CancellationToken cancellationToken)
+        {
+            return Task.FromResult(new SessionCloseResult(sessionId, SessionState.Closed, AlreadyClosed: false));
+        }
+
+        public Task<int> CloseExpiredLeasesAsync(
+            DateTimeOffset now,
+            CancellationToken cancellationToken)
+        {
+            return Task.FromResult(0);
+        }
+
+        public Task ShutdownAsync(CancellationToken cancellationToken)
+        {
+            return Task.CompletedTask;
+        }
+    }
+
+    private sealed class FakeWorkerClient : IWorkerClient
+    {
+        public List<WorkerEvent> Events { get; } = [];
+
+        public bool CompleteAfterConfiguredEvents { get; set; }
+
+        public Exception? TerminalException { get; init; }
+
+        public string SessionId { get; } = "session-events";
+
+        public int? ProcessId { get; } = 4321;
+
+        public WorkerClientState State { get; private set; } = WorkerClientState.Ready;
+
+        public DateTimeOffset LastHeartbeatAt { get; } = DateTimeOffset.UtcNow;
+
+        public Task StartAsync(CancellationToken cancellationToken)
+        {
+            return Task.CompletedTask;
+        }
+
+        public Task<WorkerCommandReply> InvokeAsync(
+            WorkerCommand command,
+            TimeSpan timeout,
+            CancellationToken cancellationToken)
+        {
+            return Task.FromResult(new WorkerCommandReply());
+        }
+
+        public async IAsyncEnumerable<WorkerEvent> ReadEventsAsync(
+            [EnumeratorCancellation] CancellationToken cancellationToken)
+        {
+            foreach (WorkerEvent workerEvent in Events)
+            {
+                cancellationToken.ThrowIfCancellationRequested();
+                yield return workerEvent;
+            }
+
+            if (TerminalException is not null)
+            {
+                throw TerminalException;
+            }
+
+            if (CompleteAfterConfiguredEvents)
+            {
+                yield break;
+            }
+
+            await Task.Delay(Timeout.InfiniteTimeSpan, cancellationToken);
+        }
+
+        public Task ShutdownAsync(
+            TimeSpan timeout,
+            CancellationToken cancellationToken)
+        {
+            State = WorkerClientState.Closed;
+            return Task.CompletedTask;
+        }
+
+        public void Kill(string reason)
+        {
+            State = WorkerClientState.Faulted;
+        }
+
+        public ValueTask DisposeAsync()
+        {
+            return ValueTask.CompletedTask;
+        }
+    }
+}

src/MxGateway.Tests/Gateway/Grpc/MxAccessGatewayServiceTests.cs

@@ -184,6 +184,7 @@ public sealed class MxAccessGatewayServiceTests
             identityAccessor ?? new GatewayRequestIdentityAccessor(),
             new MxAccessGrpcRequestValidator(),
             new MxAccessGrpcMapper(),
+            new FakeEventStreamService(sessionManager),
             NullLogger<MxAccessGatewayService>.Instance);
     }
 
@@ -275,6 +276,11 @@ public sealed class MxAccessGatewayServiceTests
 
         public List<WorkerEvent> Events { get; } = [];
 
+        public void RecordReadEventsSessionId(string sessionId)
+        {
+            LastReadEventsSessionId = sessionId;
+        }
+
         public Task<GatewaySession> OpenSessionAsync(
             SessionOpenRequest request,
             string? clientIdentity,
@@ -343,6 +349,27 @@ public sealed class MxAccessGatewayServiceTests
         }
     }
 
+    private sealed class FakeEventStreamService(FakeSessionManager sessionManager) : IEventStreamService
+    {
+        public async IAsyncEnumerable<MxEvent> StreamEventsAsync(
+            StreamEventsRequest request,
+            [EnumeratorCancellation] CancellationToken cancellationToken)
+        {
+            sessionManager.RecordReadEventsSessionId(request.SessionId);
+            foreach (WorkerEvent workerEvent in sessionManager.Events)
+            {
+                cancellationToken.ThrowIfCancellationRequested();
+                await Task.Yield();
+                if (workerEvent.Event.WorkerSequence <= request.AfterWorkerSequence)
+                {
+                    continue;
+                }
+
+                yield return workerEvent.Event;
+            }
+        }
+    }
+
     private sealed class FakeWorkerClient(int processId) : IWorkerClient
     {
         public string SessionId { get; } = "session-1";

src/MxGateway.Tests/Gateway/Sessions/SessionWorkerClientFactoryFakeWorkerTests.cs

@@ -0,0 +1,216 @@
+using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Extensions.Options;
+using MxGateway.Contracts;
+using MxGateway.Contracts.Proto;
+using MxGateway.Server.Configuration;
+using MxGateway.Server.Metrics;
+using MxGateway.Server.Sessions;
+using MxGateway.Server.Workers;
+using MxGateway.Tests.Gateway.Workers.Fakes;
+
+namespace MxGateway.Tests.Gateway.Sessions;
+
+public sealed class SessionWorkerClientFactoryFakeWorkerTests
+{
+    private static readonly TimeSpan TestTimeout = TimeSpan.FromSeconds(5);
+
+    [Fact]
+    public async Task CreateAsync_WithScriptedFakeWorker_ReturnsReadyClient()
+    {
+        ScriptedFakeWorkerProcessLauncher launcher = new();
+        using GatewayMetrics metrics = new();
+        SessionWorkerClientFactory factory = new(
+            launcher,
+            Options.Create(CreateOptions()),
+            metrics,
+            NullLoggerFactory.Instance);
+        GatewaySession session = CreateSession();
+
+        await using IWorkerClient workerClient = await factory.CreateAsync(
+            session,
+            CancellationToken.None);
+
+        Assert.Equal(WorkerClientState.Ready, workerClient.State);
+        Assert.Equal(ScriptedFakeWorkerProcessLauncher.ProcessId, workerClient.ProcessId);
+        Assert.NotNull(launcher.Harness);
+
+        Task<WorkerCommandReply> invokeTask = workerClient.InvokeAsync(
+            CreateCommand(MxCommandKind.Ping),
+            TestTimeout,
+            CancellationToken.None);
+        WorkerEnvelope commandEnvelope = await launcher.Harness.ReadCommandAsync();
+        await launcher.Harness.ReplyToCommandAsync(commandEnvelope);
+        WorkerCommandReply reply = await invokeTask.WaitAsync(TestTimeout);
+
+        Assert.Equal(MxCommandKind.Ping, reply.Reply.Kind);
+        Assert.Equal(ProtocolStatusCode.Ok, reply.Reply.ProtocolStatus.Code);
+    }
+
+    [Fact]
+    public async Task CreateAsync_WhenFakeWorkerStartupFails_ThrowsWorkerClientException()
+    {
+        FailingStartupWorkerProcessLauncher launcher = new();
+        using GatewayMetrics metrics = new();
+        SessionWorkerClientFactory factory = new(
+            launcher,
+            Options.Create(CreateOptions()),
+            metrics,
+            NullLoggerFactory.Instance);
+        GatewaySession session = CreateSession();
+
+        WorkerClientException exception = await Assert.ThrowsAsync<WorkerClientException>(
+            async () => await factory.CreateAsync(session, CancellationToken.None).WaitAsync(TestTimeout));
+
+        Assert.Equal(WorkerClientErrorCode.ProtocolViolation, exception.ErrorCode);
+        Assert.True(launcher.Process.IsDisposed);
+    }
+
+    private static GatewayOptions CreateOptions()
+    {
+        return new GatewayOptions
+        {
+            Worker = new WorkerOptions
+            {
+                StartupTimeoutSeconds = 5,
+                ShutdownTimeoutSeconds = 5,
+                HeartbeatIntervalSeconds = 30,
+                HeartbeatGraceSeconds = 30,
+                MaxMessageBytes = WorkerFrameProtocolOptions.DefaultMaxMessageBytes,
+            },
+            Events = new EventOptions
+            {
+                QueueCapacity = 16,
+            },
+        };
+    }
+
+    private static GatewaySession CreateSession()
+    {
+        return new GatewaySession(
+            FakeWorkerHarness.DefaultSessionId,
+            GatewayContractInfo.DefaultBackendName,
+            $"mxaccessgw-session-fake-worker-{Guid.NewGuid():N}",
+            FakeWorkerHarness.DefaultNonce,
+            "test-client",
+            "fake-worker-session-test",
+            "client-correlation-1",
+            TestTimeout,
+            TestTimeout,
+            TestTimeout,
+            DateTimeOffset.UtcNow);
+    }
+
+    private static WorkerCommand CreateCommand(MxCommandKind kind)
+    {
+        return new WorkerCommand
+        {
+            Command = new MxCommand
+            {
+                Kind = kind,
+            },
+        };
+    }
+
+    private sealed class ScriptedFakeWorkerProcessLauncher : IWorkerProcessLauncher
+    {
+        public const int ProcessId = 2468;
+        private readonly FakeWorkerProcess _process = new(ProcessId);
+
+        public FakeWorkerHarness? Harness { get; private set; }
+
+        public Task<WorkerProcessHandle> LaunchAsync(
+            WorkerProcessLaunchRequest request,
+            CancellationToken cancellationToken = default)
+        {
+            _ = RunWorkerAsync(request, cancellationToken);
+
+            return Task.FromResult(CreateHandle(_process));
+        }
+
+        private async Task RunWorkerAsync(
+            WorkerProcessLaunchRequest request,
+            CancellationToken cancellationToken)
+        {
+            Harness = await FakeWorkerHarness.ConnectToGatewayPipeAsync(
+                request.SessionId,
+                request.Nonce,
+                request.PipeName,
+                request.ProtocolVersion,
+                cancellationToken: cancellationToken).ConfigureAwait(false);
+            await Harness.CompleteStartupAsync(ProcessId, cancellationToken: cancellationToken).ConfigureAwait(false);
+        }
+    }
+
+    private sealed class FailingStartupWorkerProcessLauncher : IWorkerProcessLauncher
+    {
+        public FakeWorkerProcess Process { get; } = new(processId: 3579);
+
+        public Task<WorkerProcessHandle> LaunchAsync(
+            WorkerProcessLaunchRequest request,
+            CancellationToken cancellationToken = default)
+        {
+            _ = RunWorkerAsync(request, cancellationToken);
+
+            return Task.FromResult(CreateHandle(Process));
+        }
+
+        private async Task RunWorkerAsync(
+            WorkerProcessLaunchRequest request,
+            CancellationToken cancellationToken)
+        {
+            await using FakeWorkerHarness harness = await FakeWorkerHarness.ConnectToGatewayPipeAsync(
+                request.SessionId,
+                request.Nonce,
+                request.PipeName,
+                request.ProtocolVersion,
+                cancellationToken: cancellationToken).ConfigureAwait(false);
+            _ = await harness.ReadGatewayEnvelopeAsync(cancellationToken).ConfigureAwait(false);
+            await harness.SendWorkerHelloAsync(
+                workerProcessId: Process.Id,
+                workerProtocolVersion: request.ProtocolVersion + 1,
+                cancellationToken: cancellationToken).ConfigureAwait(false);
+        }
+    }
+
+    private static WorkerProcessHandle CreateHandle(IWorkerProcess process)
+    {
+        return new WorkerProcessHandle(
+            process,
+            new WorkerProcessCommandLine("fake-worker.exe", []),
+            DateTimeOffset.UtcNow);
+    }
+
+    private sealed class FakeWorkerProcess(int processId) : IWorkerProcess
+    {
+        private bool _disposed;
+
+        public int Id { get; } = processId;
+
+        public bool HasExited { get; private set; }
+
+        public int? ExitCode { get; private set; }
+
+        public int KillCount { get; private set; }
+
+        public ValueTask WaitForExitAsync(CancellationToken cancellationToken)
+        {
+            HasExited = true;
+            ExitCode = 0;
+            return ValueTask.CompletedTask;
+        }
+
+        public void Kill(bool entireProcessTree)
+        {
+            KillCount++;
+            HasExited = true;
+            ExitCode = -1;
+        }
+
+        public void Dispose()
+        {
+            _disposed = true;
+        }
+
+        public bool IsDisposed => _disposed;
+    }
+}

src/MxGateway.Tests/Gateway/Workers/FakeWorkerHarnessTests.cs

@@ -0,0 +1,190 @@
+using MxGateway.Contracts;
+using MxGateway.Contracts.Proto;
+using MxGateway.Server.Workers;
+using MxGateway.Tests.Gateway.Workers.Fakes;
+
+namespace MxGateway.Tests.Gateway.Workers;
+
+public sealed class FakeWorkerHarnessTests
+{
+    private static readonly TimeSpan TestTimeout = TimeSpan.FromSeconds(5);
+
+    [Fact]
+    public async Task CompleteStartupAsync_WithHelloAndReady_TransitionsClientToReady()
+    {
+        await using FakeWorkerHarness fakeWorker = await FakeWorkerHarness.CreateConnectedPairAsync();
+        await using WorkerClient client = fakeWorker.CreateClient();
+
+        Task startTask = client.StartAsync(CancellationToken.None);
+        WorkerEnvelope gatewayHello = await fakeWorker.CompleteStartupAsync();
+        await startTask.WaitAsync(TestTimeout);
+
+        Assert.Equal(WorkerEnvelope.BodyOneofCase.GatewayHello, gatewayHello.BodyCase);
+        Assert.Equal(FakeWorkerHarness.DefaultNonce, gatewayHello.GatewayHello.Nonce);
+        Assert.Equal(WorkerClientState.Ready, client.State);
+        Assert.Equal(FakeWorkerHarness.DefaultWorkerProcessId, client.ProcessId);
+    }
+
+    [Fact]
+    public async Task StartAsync_WithProtocolMismatch_FailsStartup()
+    {
+        await using FakeWorkerHarness fakeWorker = await FakeWorkerHarness.CreateConnectedPairAsync();
+        await using WorkerClient client = fakeWorker.CreateClient();
+
+        Task startTask = client.StartAsync(CancellationToken.None);
+        WorkerEnvelope gatewayHello = await fakeWorker.ReadGatewayEnvelopeAsync();
+        Assert.Equal(WorkerEnvelope.BodyOneofCase.GatewayHello, gatewayHello.BodyCase);
+        await fakeWorker.SendWorkerHelloAsync(
+            workerProtocolVersion: GatewayContractInfo.WorkerProtocolVersion + 1);
+
+        WorkerClientException exception = await Assert.ThrowsAsync<WorkerClientException>(
+            async () => await startTask.WaitAsync(TestTimeout));
+
+        Assert.Equal(WorkerClientErrorCode.ProtocolViolation, exception.ErrorCode);
+    }
+
+    [Fact]
+    public async Task InvokeAsync_WithScriptedReply_CompletesCommand()
+    {
+        await using FakeWorkerHarness fakeWorker = await FakeWorkerHarness.CreateConnectedPairAsync();
+        await using WorkerClient client = fakeWorker.CreateClient();
+        await StartClientAsync(fakeWorker, client);
+
+        Task<WorkerCommandReply> invokeTask = client.InvokeAsync(
+            CreateCommand(MxCommandKind.Ping),
+            TestTimeout,
+            CancellationToken.None);
+        WorkerEnvelope commandEnvelope = await fakeWorker.ReadCommandAsync();
+        await fakeWorker.ReplyToCommandAsync(commandEnvelope);
+
+        WorkerCommandReply reply = await invokeTask.WaitAsync(TestTimeout);
+
+        Assert.Equal(commandEnvelope.CorrelationId, reply.Reply.CorrelationId);
+        Assert.Equal(MxCommandKind.Ping, reply.Reply.Kind);
+        Assert.Equal(ProtocolStatusCode.Ok, reply.Reply.ProtocolStatus.Code);
+    }
+
+    [Fact]
+    public async Task ReadEventsAsync_WithScriptedEvents_YieldsOrderedEvents()
+    {
+        await using FakeWorkerHarness fakeWorker = await FakeWorkerHarness.CreateConnectedPairAsync();
+        await using WorkerClient client = fakeWorker.CreateClient();
+        await StartClientAsync(fakeWorker, client);
+        using CancellationTokenSource cancellationTokenSource = new(TestTimeout);
+
+        await using IAsyncEnumerator<WorkerEvent> events =
+            client.ReadEventsAsync(cancellationTokenSource.Token).GetAsyncEnumerator(cancellationTokenSource.Token);
+
+        await fakeWorker.EmitEventAsync(MxEventFamily.OnDataChange, cancellationTokenSource.Token);
+        await fakeWorker.EmitEventAsync(MxEventFamily.OperationComplete, cancellationTokenSource.Token);
+
+        Assert.True(await events.MoveNextAsync());
+        Assert.Equal((ulong)3, events.Current.Event.WorkerSequence);
+        Assert.Equal(MxEventFamily.OnDataChange, events.Current.Event.Family);
+
+        Assert.True(await events.MoveNextAsync());
+        Assert.Equal((ulong)4, events.Current.Event.WorkerSequence);
+        Assert.Equal(MxEventFamily.OperationComplete, events.Current.Event.Family);
+    }
+
+    [Fact]
+    public async Task ReadLoop_WithScriptedFault_FaultsClient()
+    {
+        await using FakeWorkerHarness fakeWorker = await FakeWorkerHarness.CreateConnectedPairAsync();
+        await using WorkerClient client = fakeWorker.CreateClient();
+        await StartClientAsync(fakeWorker, client);
+
+        await fakeWorker.EmitFaultAsync(
+            WorkerFaultCategory.MxaccessCommandFailed,
+            "scripted MXAccess command fault");
+
+        await WaitUntilAsync(
+            () => client.State == WorkerClientState.Faulted,
+            TestTimeout);
+
+        Assert.Equal(WorkerClientState.Faulted, client.State);
+    }
+
+    [Fact]
+    public async Task InvokeAsync_WithHungWorker_TimesOutPendingCommand()
+    {
+        await using FakeWorkerHarness fakeWorker = await FakeWorkerHarness.CreateConnectedPairAsync();
+        await using WorkerClient client = fakeWorker.CreateClient();
+        await StartClientAsync(fakeWorker, client);
+
+        Task<WorkerCommandReply> invokeTask = client.InvokeAsync(
+            CreateCommand(MxCommandKind.Ping),
+            TimeSpan.FromMilliseconds(50),
+            CancellationToken.None);
+        WorkerEnvelope commandEnvelope = await fakeWorker.ReadCommandAsync();
+
+        WorkerClientException exception = await Assert.ThrowsAsync<WorkerClientException>(
+            async () => await invokeTask.WaitAsync(TestTimeout));
+
+        Assert.Equal(WorkerEnvelope.BodyOneofCase.WorkerCommand, commandEnvelope.BodyCase);
+        Assert.Equal(WorkerClientErrorCode.CommandTimeout, exception.ErrorCode);
+    }
+
+    [Fact]
+    public async Task ReadLoop_WithMalformedFrame_FaultsClient()
+    {
+        await using FakeWorkerHarness fakeWorker = await FakeWorkerHarness.CreateConnectedPairAsync();
+        await using WorkerClient client = fakeWorker.CreateClient();
+        await StartClientAsync(fakeWorker, client);
+
+        await fakeWorker.WriteMalformedPayloadAsync(new byte[] { 0x08, 0x96, 0x01 });
+
+        await WaitUntilAsync(
+            () => client.State == WorkerClientState.Faulted,
+            TestTimeout);
+
+        Assert.Equal(WorkerClientState.Faulted, client.State);
+    }
+
+    [Fact]
+    public async Task ShutdownAsync_WithShutdownAck_ClosesClient()
+    {
+        await using FakeWorkerHarness fakeWorker = await FakeWorkerHarness.CreateConnectedPairAsync();
+        await using WorkerClient client = fakeWorker.CreateClient();
+        await StartClientAsync(fakeWorker, client);
+
+        Task shutdownTask = client.ShutdownAsync(TestTimeout, CancellationToken.None);
+        WorkerEnvelope shutdownEnvelope = await fakeWorker.ReadShutdownAsync();
+        await fakeWorker.SendShutdownAckAsync();
+        await shutdownTask.WaitAsync(TestTimeout);
+
+        Assert.Equal(WorkerEnvelope.BodyOneofCase.WorkerShutdown, shutdownEnvelope.BodyCase);
+        Assert.Equal(WorkerClientState.Closed, client.State);
+    }
+
+    private static async Task StartClientAsync(
+        FakeWorkerHarness fakeWorker,
+        WorkerClient client)
+    {
+        Task startTask = client.StartAsync(CancellationToken.None);
+        await fakeWorker.CompleteStartupAsync().ConfigureAwait(false);
+        await startTask.WaitAsync(TestTimeout).ConfigureAwait(false);
+    }
+
+    private static WorkerCommand CreateCommand(MxCommandKind kind)
+    {
+        return new WorkerCommand
+        {
+            Command = new MxCommand
+            {
+                Kind = kind,
+            },
+        };
+    }
+
+    private static async Task WaitUntilAsync(
+        Func<bool> predicate,
+        TimeSpan timeout)
+    {
+        using CancellationTokenSource cancellationTokenSource = new(timeout);
+        while (!predicate())
+        {
+            await Task.Delay(TimeSpan.FromMilliseconds(10), cancellationTokenSource.Token);
+        }
+    }
+}

src/MxGateway.Tests/Gateway/Workers/Fakes/FakeWorkerHarness.cs

@@ -0,0 +1,386 @@
+using System.Buffers.Binary;
+using System.IO.Pipes;
+using Google.Protobuf.WellKnownTypes;
+using MxGateway.Contracts;
+using MxGateway.Contracts.Proto;
+using MxGateway.Server.Metrics;
+using MxGateway.Server.Workers;
+
+namespace MxGateway.Tests.Gateway.Workers.Fakes;
+
+public sealed class FakeWorkerHarness : IAsyncDisposable
+{
+    public const string DefaultSessionId = "session-fake-worker";
+    public const string DefaultNonce = "nonce-fake-worker";
+    public const int DefaultWorkerProcessId = 9321;
+
+    private readonly NamedPipeServerStream? _gatewayStream;
+    private readonly NamedPipeClientStream _workerStream;
+    private readonly WorkerFrameProtocolOptions _frameOptions;
+    private readonly WorkerFrameReader _reader;
+    private readonly WorkerFrameWriter _writer;
+    private bool _workerSideDisposed;
+
+    private FakeWorkerHarness(
+        string sessionId,
+        string nonce,
+        NamedPipeServerStream? gatewayStream,
+        NamedPipeClientStream workerStream,
+        WorkerFrameProtocolOptions frameOptions)
+    {
+        SessionId = sessionId;
+        Nonce = nonce;
+        _gatewayStream = gatewayStream;
+        _workerStream = workerStream;
+        _frameOptions = frameOptions;
+        _reader = new WorkerFrameReader(_workerStream, frameOptions);
+        _writer = new WorkerFrameWriter(_workerStream, frameOptions);
+    }
+
+    public string SessionId { get; }
+
+    public string Nonce { get; }
+
+    public ulong NextWorkerSequence { get; private set; }
+
+    public static async Task<FakeWorkerHarness> CreateConnectedPairAsync(
+        string sessionId = DefaultSessionId,
+        string nonce = DefaultNonce,
+        uint protocolVersion = GatewayContractInfo.WorkerProtocolVersion,
+        int maxMessageBytes = WorkerFrameProtocolOptions.DefaultMaxMessageBytes,
+        CancellationToken cancellationToken = default)
+    {
+        string pipeName = $"mxaccessgw-fake-worker-{Guid.NewGuid():N}";
+        NamedPipeServerStream gatewayStream = new(
+            pipeName,
+            PipeDirection.InOut,
+            maxNumberOfServerInstances: 1,
+            PipeTransmissionMode.Byte,
+            PipeOptions.Asynchronous);
+        NamedPipeClientStream workerStream = CreateWorkerStream(pipeName);
+
+        Task waitForConnectionTask = gatewayStream.WaitForConnectionAsync(cancellationToken);
+        await workerStream.ConnectAsync(cancellationToken).ConfigureAwait(false);
+        await waitForConnectionTask.ConfigureAwait(false);
+
+        return new FakeWorkerHarness(
+            sessionId,
+            nonce,
+            gatewayStream,
+            workerStream,
+            new WorkerFrameProtocolOptions(sessionId, protocolVersion, maxMessageBytes));
+    }
+
+    public static async Task<FakeWorkerHarness> ConnectToGatewayPipeAsync(
+        string sessionId,
+        string nonce,
+        string pipeName,
+        uint protocolVersion = GatewayContractInfo.WorkerProtocolVersion,
+        int maxMessageBytes = WorkerFrameProtocolOptions.DefaultMaxMessageBytes,
+        CancellationToken cancellationToken = default)
+    {
+        NamedPipeClientStream workerStream = CreateWorkerStream(pipeName);
+        await workerStream.ConnectAsync(cancellationToken).ConfigureAwait(false);
+
+        return new FakeWorkerHarness(
+            sessionId,
+            nonce,
+            gatewayStream: null,
+            workerStream,
+            new WorkerFrameProtocolOptions(sessionId, protocolVersion, maxMessageBytes));
+    }
+
+    public WorkerClient CreateClient(
+        WorkerClientOptions? options = null,
+        GatewayMetrics? metrics = null,
+        TimeProvider? timeProvider = null)
+    {
+        if (_gatewayStream is null)
+        {
+            throw new InvalidOperationException("This fake worker is connected to a gateway-owned pipe.");
+        }
+
+        WorkerClientConnection connection = new(
+            SessionId,
+            Nonce,
+            _gatewayStream,
+            _frameOptions);
+
+        return new WorkerClient(connection, options, metrics, timeProvider);
+    }
+
+    public async Task<WorkerEnvelope> CompleteStartupAsync(
+        int workerProcessId = DefaultWorkerProcessId,
+        string workerVersion = "fake-worker",
+        string mxaccessProgid = "LMXProxy.LMXProxyServer.1",
+        string mxaccessClsid = "{C30B52F5-2CB5-4760-AF0A-3A344A7EB5DC}",
+        CancellationToken cancellationToken = default)
+    {
+        WorkerEnvelope gatewayHello = await ReadGatewayEnvelopeAsync(cancellationToken).ConfigureAwait(false);
+        if (gatewayHello.BodyCase != WorkerEnvelope.BodyOneofCase.GatewayHello)
+        {
+            throw new InvalidOperationException($"Expected GatewayHello but received {gatewayHello.BodyCase}.");
+        }
+
+        await SendWorkerHelloAsync(
+            workerProcessId,
+            workerVersion,
+            cancellationToken: cancellationToken).ConfigureAwait(false);
+        await SendWorkerReadyAsync(
+            workerProcessId,
+            mxaccessProgid,
+            mxaccessClsid,
+            cancellationToken).ConfigureAwait(false);
+
+        return gatewayHello;
+    }
+
+    public async Task<WorkerEnvelope> ReadGatewayEnvelopeAsync(CancellationToken cancellationToken = default)
+    {
+        return await _reader.ReadAsync(cancellationToken).ConfigureAwait(false);
+    }
+
+    public async Task<WorkerEnvelope> ReadCommandAsync(CancellationToken cancellationToken = default)
+    {
+        WorkerEnvelope envelope = await ReadGatewayEnvelopeAsync(cancellationToken).ConfigureAwait(false);
+        if (envelope.BodyCase != WorkerEnvelope.BodyOneofCase.WorkerCommand)
+        {
+            throw new InvalidOperationException($"Expected WorkerCommand but received {envelope.BodyCase}.");
+        }
+
+        return envelope;
+    }
+
+    public async Task<WorkerEnvelope> ReadShutdownAsync(CancellationToken cancellationToken = default)
+    {
+        WorkerEnvelope envelope = await ReadGatewayEnvelopeAsync(cancellationToken).ConfigureAwait(false);
+        if (envelope.BodyCase != WorkerEnvelope.BodyOneofCase.WorkerShutdown)
+        {
+            throw new InvalidOperationException($"Expected WorkerShutdown but received {envelope.BodyCase}.");
+        }
+
+        return envelope;
+    }
+
+    public async Task SendWorkerHelloAsync(
+        int workerProcessId = DefaultWorkerProcessId,
+        string workerVersion = "fake-worker",
+        uint? workerProtocolVersion = null,
+        string? nonce = null,
+        CancellationToken cancellationToken = default)
+    {
+        await _writer.WriteAsync(
+            CreateEnvelope(
+                correlationId: string.Empty,
+                envelope => envelope.WorkerHello = new WorkerHello
+                {
+                    ProtocolVersion = workerProtocolVersion ?? _frameOptions.ProtocolVersion,
+                    Nonce = nonce ?? Nonce,
+                    WorkerProcessId = workerProcessId,
+                    WorkerVersion = workerVersion,
+                }),
+            cancellationToken).ConfigureAwait(false);
+    }
+
+    public async Task SendWorkerReadyAsync(
+        int workerProcessId = DefaultWorkerProcessId,
+        string mxaccessProgid = "LMXProxy.LMXProxyServer.1",
+        string mxaccessClsid = "{C30B52F5-2CB5-4760-AF0A-3A344A7EB5DC}",
+        CancellationToken cancellationToken = default)
+    {
+        await _writer.WriteAsync(
+            CreateEnvelope(
+                correlationId: string.Empty,
+                envelope => envelope.WorkerReady = new WorkerReady
+                {
+                    WorkerProcessId = workerProcessId,
+                    MxaccessProgid = mxaccessProgid,
+                    MxaccessClsid = mxaccessClsid,
+                    ReadyTimestamp = Timestamp.FromDateTimeOffset(DateTimeOffset.UtcNow),
+                }),
+            cancellationToken).ConfigureAwait(false);
+    }
+
+    public async Task ReplyToCommandAsync(
+        WorkerEnvelope commandEnvelope,
+        ProtocolStatusCode statusCode = ProtocolStatusCode.Ok,
+        string statusMessage = "OK",
+        Action<MxCommandReply>? configureReply = null,
+        CancellationToken cancellationToken = default)
+    {
+        if (commandEnvelope.BodyCase != WorkerEnvelope.BodyOneofCase.WorkerCommand)
+        {
+            throw new ArgumentException("Command envelope must contain WorkerCommand.", nameof(commandEnvelope));
+        }
+
+        MxCommandKind kind = commandEnvelope.WorkerCommand.Command?.Kind ?? MxCommandKind.Unspecified;
+        MxCommandReply reply = new()
+        {
+            SessionId = SessionId,
+            CorrelationId = commandEnvelope.CorrelationId,
+            Kind = kind,
+            ProtocolStatus = new ProtocolStatus
+            {
+                Code = statusCode,
+                Message = statusMessage,
+            },
+        };
+        configureReply?.Invoke(reply);
+
+        await _writer.WriteAsync(
+            CreateEnvelope(
+                commandEnvelope.CorrelationId,
+                envelope => envelope.WorkerCommandReply = new WorkerCommandReply
+                {
+                    Reply = reply,
+                    CompletedTimestamp = Timestamp.FromDateTimeOffset(DateTimeOffset.UtcNow),
+                }),
+            cancellationToken).ConfigureAwait(false);
+    }
+
+    public async Task EmitEventAsync(
+        MxEventFamily family,
+        CancellationToken cancellationToken = default,
+        Action<MxEvent>? configureEvent = null)
+    {
+        ulong sequence = NextWorkerSequence + 1;
+        MxEvent mxEvent = new()
+        {
+            SessionId = SessionId,
+            Family = family,
+            WorkerSequence = sequence,
+            WorkerTimestamp = Timestamp.FromDateTimeOffset(DateTimeOffset.UtcNow),
+        };
+        configureEvent?.Invoke(mxEvent);
+
+        await _writer.WriteAsync(
+            CreateEnvelope(
+                correlationId: string.Empty,
+                envelope => envelope.WorkerEvent = new WorkerEvent
+                {
+                    Event = mxEvent,
+                }),
+            cancellationToken).ConfigureAwait(false);
+    }
+
+    public async Task EmitFaultAsync(
+        WorkerFaultCategory category,
+        string diagnosticMessage,
+        CancellationToken cancellationToken = default)
+    {
+        await _writer.WriteAsync(
+            CreateEnvelope(
+                correlationId: string.Empty,
+                envelope => envelope.WorkerFault = new WorkerFault
+                {
+                    Category = category,
+                    DiagnosticMessage = diagnosticMessage,
+                    ProtocolStatus = new ProtocolStatus
+                    {
+                        Code = ProtocolStatusCode.WorkerUnavailable,
+                        Message = diagnosticMessage,
+                    },
+                }),
+            cancellationToken).ConfigureAwait(false);
+    }
+
+    public async Task SendShutdownAckAsync(
+        ProtocolStatusCode statusCode = ProtocolStatusCode.Ok,
+        CancellationToken cancellationToken = default)
+    {
+        await _writer.WriteAsync(
+            CreateEnvelope(
+                correlationId: string.Empty,
+                envelope => envelope.WorkerShutdownAck = new WorkerShutdownAck
+                {
+                    Status = new ProtocolStatus
+                    {
+                        Code = statusCode,
+                        Message = statusCode.ToString(),
+                    },
+                }),
+            cancellationToken).ConfigureAwait(false);
+    }
+
+    public async Task WriteMalformedPayloadAsync(
+        ReadOnlyMemory<byte> payload,
+        CancellationToken cancellationToken = default)
+    {
+        if (payload.IsEmpty)
+        {
+            throw new ArgumentException("Malformed payload must include at least one byte.", nameof(payload));
+        }
+
+        byte[] lengthPrefix = new byte[sizeof(uint)];
+        BinaryPrimitives.WriteUInt32LittleEndian(lengthPrefix, (uint)payload.Length);
+        await _workerStream.WriteAsync(lengthPrefix, cancellationToken).ConfigureAwait(false);
+        await _workerStream.WriteAsync(payload, cancellationToken).ConfigureAwait(false);
+    }
+
+    public async Task WriteOversizedFrameHeaderAsync(
+        uint payloadLength,
+        CancellationToken cancellationToken = default)
+    {
+        if (payloadLength <= _frameOptions.MaxMessageBytes)
+        {
+            throw new ArgumentOutOfRangeException(
+                nameof(payloadLength),
+                payloadLength,
+                "Payload length must exceed the configured maximum.");
+        }
+
+        byte[] lengthPrefix = new byte[sizeof(uint)];
+        BinaryPrimitives.WriteUInt32LittleEndian(lengthPrefix, payloadLength);
+        await _workerStream.WriteAsync(lengthPrefix, cancellationToken).ConfigureAwait(false);
+    }
+
+    public async ValueTask DisposeWorkerSideAsync()
+    {
+        if (_workerSideDisposed)
+        {
+            return;
+        }
+
+        await _workerStream.DisposeAsync().ConfigureAwait(false);
+        _workerSideDisposed = true;
+    }
+
+    public async ValueTask DisposeAsync()
+    {
+        await DisposeWorkerSideAsync().ConfigureAwait(false);
+        if (_gatewayStream is not null)
+        {
+            await _gatewayStream.DisposeAsync().ConfigureAwait(false);
+        }
+    }
+
+    private WorkerEnvelope CreateEnvelope(
+        string correlationId,
+        Action<WorkerEnvelope> setBody)
+    {
+        WorkerEnvelope envelope = new()
+        {
+            ProtocolVersion = _frameOptions.ProtocolVersion,
+            SessionId = SessionId,
+            Sequence = AdvanceSequence(),
+            CorrelationId = correlationId,
+        };
+        setBody(envelope);
+
+        return envelope;
+    }
+
+    private ulong AdvanceSequence()
+    {
+        return ++NextWorkerSequence;
+    }
+
+    private static NamedPipeClientStream CreateWorkerStream(string pipeName)
+    {
+        return new NamedPipeClientStream(
+            ".",
+            pipeName,
+            PipeDirection.InOut,
+            PipeOptions.Asynchronous);
+    }
+}

src/MxGateway.Tests/Gateway/Workers/WorkerClientTests.cs

@@ -109,6 +109,32 @@ public sealed class WorkerClientTests
         Assert.Equal(MxEventFamily.OperationComplete, events.Current.Event.Family);
     }
 
+    [Fact]
+    public async Task ReadLoop_WhenEventQueueOverflows_FaultsClient()
+    {
+        await using PipePair pipePair = await PipePair.CreateAsync();
+        await using WorkerClient client = CreateClient(
+            pipePair,
+            new WorkerClientOptions
+            {
+                EventChannelCapacity = 1,
+                HeartbeatGrace = TimeSpan.FromSeconds(30),
+                HeartbeatCheckInterval = TimeSpan.FromSeconds(30),
+            });
+        await CompleteHandshakeAsync(client, pipePair);
+
+        await pipePair.WorkerWriter.WriteAsync(
+            CreateEventEnvelope(sequence: 11, MxEventFamily.OnDataChange));
+        await pipePair.WorkerWriter.WriteAsync(
+            CreateEventEnvelope(sequence: 12, MxEventFamily.OnDataChange));
+
+        await WaitUntilAsync(
+            () => client.State == WorkerClientState.Faulted,
+            TestTimeout);
+
+        Assert.Equal(WorkerClientState.Faulted, client.State);
+    }
+
     [Fact]
     public async Task ReadLoop_WhenPipeDisconnects_FaultsClient()
     {

src/MxGateway.Worker.Tests/MxAccess/MxAccessCommandExecutorTests.cs

@@ -0,0 +1,542 @@
+using System;
+using System.Runtime.InteropServices;
+using System.Threading.Tasks;
+using MxGateway.Contracts.Proto;
+using MxGateway.Worker.MxAccess;
+using MxGateway.Worker.Sta;
+
+namespace MxGateway.Worker.Tests.MxAccess;
+
+public sealed class MxAccessCommandExecutorTests
+{
+    [Fact]
+    public async Task DispatchAsync_Register_CallsMxAccessOnStaAndPreservesServerHandle()
+    {
+        FakeMxAccessComObjectFactory factory = new(new FakeMxAccessComObject(registerHandle: 42));
+        using StaRuntime runtime = CreateRuntime();
+        using MxAccessStaSession session = new(runtime, factory, new NoopEventSink());
+        await session.StartAsync(workerProcessId: 1234);
+
+        MxCommandReply reply = await session.DispatchAsync(CreateRegisterCommand("correlation-1", "client-a"));
+
+        Assert.Equal(ProtocolStatusCode.Ok, reply.ProtocolStatus.Code);
+        Assert.True(reply.HasHresult);
+        Assert.Equal(0, reply.Hresult);
+        Assert.Equal(42, reply.Register.ServerHandle);
+        Assert.Equal(MxDataType.Integer, reply.ReturnValue.DataType);
+        Assert.Equal(42, reply.ReturnValue.Int32Value);
+        Assert.Equal(runtime.StaThreadId, factory.FakeComObject.RegisterThreadId);
+        Assert.Equal("client-a", factory.FakeComObject.RegisteredClientName);
+
+        RegisteredServerHandle registeredServerHandle = Assert.Single(
+            await session.GetRegisteredServerHandlesAsync());
+        Assert.Equal(42, registeredServerHandle.ServerHandle);
+        Assert.Equal("client-a", registeredServerHandle.ClientName);
+    }
+
+    [Fact]
+    public async Task DispatchAsync_Unregister_CallsMxAccessOnStaAndRemovesTrackedServerHandle()
+    {
+        FakeMxAccessComObject fakeComObject = new(registerHandle: 43);
+        FakeMxAccessComObjectFactory factory = new(fakeComObject);
+        using StaRuntime runtime = CreateRuntime();
+        using MxAccessStaSession session = new(runtime, factory, new NoopEventSink());
+        await session.StartAsync(workerProcessId: 1234);
+        await session.DispatchAsync(CreateRegisterCommand("register", "client-a"));
+
+        MxCommandReply reply = await session.DispatchAsync(CreateUnregisterCommand("unregister", 43));
+
+        Assert.Equal(ProtocolStatusCode.Ok, reply.ProtocolStatus.Code);
+        Assert.Equal(43, fakeComObject.UnregisteredServerHandle);
+        Assert.Equal(runtime.StaThreadId, fakeComObject.UnregisterThreadId);
+        Assert.Empty(await session.GetRegisteredServerHandlesAsync());
+    }
+
+    [Fact]
+    public async Task DispatchAsync_UnregisterWhenMxAccessThrows_PreservesHResultAndDoesNotRewriteFailure()
+    {
+        const int hresult = unchecked((int)0x80070057);
+        FakeMxAccessComObject fakeComObject = new(
+            registerHandle: 44,
+            unregisterException: new COMException("Invalid handle.", hresult));
+        FakeMxAccessComObjectFactory factory = new(fakeComObject);
+        using StaRuntime runtime = CreateRuntime();
+        using MxAccessStaSession session = new(runtime, factory, new NoopEventSink());
+        await session.StartAsync(workerProcessId: 1234);
+        await session.DispatchAsync(CreateRegisterCommand("register-before-failure", "client-a"));
+
+        MxCommandReply reply = await session.DispatchAsync(CreateUnregisterCommand("invalid-unregister", 44));
+
+        Assert.Equal(ProtocolStatusCode.MxaccessFailure, reply.ProtocolStatus.Code);
+        Assert.True(reply.HasHresult);
+        Assert.Equal(hresult, reply.Hresult);
+        Assert.Contains("0x80070057", reply.DiagnosticMessage);
+        Assert.Equal(44, fakeComObject.UnregisteredServerHandle);
+
+        RegisteredServerHandle registeredServerHandle = Assert.Single(
+            await session.GetRegisteredServerHandlesAsync());
+        Assert.Equal(44, registeredServerHandle.ServerHandle);
+    }
+
+    [Fact]
+    public async Task DispatchAsync_AddItem_CallsMxAccessOnStaAndTracksItemHandle()
+    {
+        FakeMxAccessComObject fakeComObject = new(
+            registerHandle: 46,
+            addItemHandle: 501);
+        FakeMxAccessComObjectFactory factory = new(fakeComObject);
+        using StaRuntime runtime = CreateRuntime();
+        using MxAccessStaSession session = new(runtime, factory, new NoopEventSink());
+        await session.StartAsync(workerProcessId: 1234);
+        await session.DispatchAsync(CreateRegisterCommand("register-before-add", "client-a"));
+
+        MxCommandReply reply = await session.DispatchAsync(CreateAddItemCommand(
+            "add-item",
+            46,
+            "Galaxy.Tag.Value"));
+
+        Assert.Equal(ProtocolStatusCode.Ok, reply.ProtocolStatus.Code);
+        Assert.True(reply.HasHresult);
+        Assert.Equal(0, reply.Hresult);
+        Assert.Equal(501, reply.AddItem.ItemHandle);
+        Assert.Equal(MxDataType.Integer, reply.ReturnValue.DataType);
+        Assert.Equal(501, reply.ReturnValue.Int32Value);
+        Assert.Equal(46, fakeComObject.AddItemServerHandle);
+        Assert.Equal("Galaxy.Tag.Value", fakeComObject.AddItemDefinition);
+        Assert.Equal(runtime.StaThreadId, fakeComObject.AddItemThreadId);
+
+        RegisteredItemHandle registeredItemHandle = Assert.Single(
+            await session.GetRegisteredItemHandlesAsync());
+        Assert.Equal(46, registeredItemHandle.ServerHandle);
+        Assert.Equal(501, registeredItemHandle.ItemHandle);
+        Assert.Equal("Galaxy.Tag.Value", registeredItemHandle.ItemDefinition);
+        Assert.Equal(string.Empty, registeredItemHandle.ItemContext);
+        Assert.False(registeredItemHandle.HasItemContext);
+    }
+
+    [Fact]
+    public async Task DispatchAsync_AddItem2_PassesContextExactlyAndTracksItemHandle()
+    {
+        FakeMxAccessComObject fakeComObject = new(
+            registerHandle: 47,
+            addItem2Handle: 502);
+        FakeMxAccessComObjectFactory factory = new(fakeComObject);
+        using StaRuntime runtime = CreateRuntime();
+        using MxAccessStaSession session = new(runtime, factory, new NoopEventSink());
+        await session.StartAsync(workerProcessId: 1234);
+        await session.DispatchAsync(CreateRegisterCommand("register-before-add2", "client-a"));
+
+        MxCommandReply reply = await session.DispatchAsync(CreateAddItem2Command(
+            "add-item2",
+            47,
+            "TestInt",
+            "TestChildObject"));
+
+        Assert.Equal(ProtocolStatusCode.Ok, reply.ProtocolStatus.Code);
+        Assert.Equal(502, reply.AddItem2.ItemHandle);
+        Assert.Equal(MxDataType.Integer, reply.ReturnValue.DataType);
+        Assert.Equal(502, reply.ReturnValue.Int32Value);
+        Assert.Equal(47, fakeComObject.AddItem2ServerHandle);
+        Assert.Equal("TestInt", fakeComObject.AddItem2Definition);
+        Assert.Equal("TestChildObject", fakeComObject.AddItem2Context);
+        Assert.Equal(runtime.StaThreadId, fakeComObject.AddItem2ThreadId);
+
+        RegisteredItemHandle registeredItemHandle = Assert.Single(
+            await session.GetRegisteredItemHandlesAsync());
+        Assert.Equal(47, registeredItemHandle.ServerHandle);
+        Assert.Equal(502, registeredItemHandle.ItemHandle);
+        Assert.Equal("TestInt", registeredItemHandle.ItemDefinition);
+        Assert.Equal("TestChildObject", registeredItemHandle.ItemContext);
+        Assert.True(registeredItemHandle.HasItemContext);
+    }
+
+    [Fact]
+    public async Task DispatchAsync_RemoveItem_CallsMxAccessOnStaAndRemovesTrackedItemHandle()
+    {
+        FakeMxAccessComObject fakeComObject = new(
+            registerHandle: 48,
+            addItemHandle: 503);
+        FakeMxAccessComObjectFactory factory = new(fakeComObject);
+        using StaRuntime runtime = CreateRuntime();
+        using MxAccessStaSession session = new(runtime, factory, new NoopEventSink());
+        await session.StartAsync(workerProcessId: 1234);
+        await session.DispatchAsync(CreateRegisterCommand("register-before-remove", "client-a"));
+        await session.DispatchAsync(CreateAddItemCommand("add-before-remove", 48, "Galaxy.Tag.Value"));
+
+        MxCommandReply reply = await session.DispatchAsync(CreateRemoveItemCommand(
+            "remove-item",
+            48,
+            503));
+
+        Assert.Equal(ProtocolStatusCode.Ok, reply.ProtocolStatus.Code);
+        Assert.True(reply.HasHresult);
+        Assert.Equal(0, reply.Hresult);
+        Assert.Equal(48, fakeComObject.RemoveItemServerHandle);
+        Assert.Equal(503, fakeComObject.RemovedItemHandle);
+        Assert.Equal(runtime.StaThreadId, fakeComObject.RemoveItemThreadId);
+        Assert.Empty(await session.GetRegisteredItemHandlesAsync());
+    }
+
+    [Fact]
+    public async Task DispatchAsync_RemoveItemWithCrossServerHandle_PreservesHResultAndKeepsTrackedItemHandle()
+    {
+        const int hresult = unchecked((int)0x80070057);
+        FakeMxAccessComObject fakeComObject = new(
+            registerHandle: 49,
+            addItemHandle: 504,
+            removeItemException: new COMException("Invalid item handle.", hresult));
+        FakeMxAccessComObjectFactory factory = new(fakeComObject);
+        using StaRuntime runtime = CreateRuntime();
+        using MxAccessStaSession session = new(runtime, factory, new NoopEventSink());
+        await session.StartAsync(workerProcessId: 1234);
+        await session.DispatchAsync(CreateRegisterCommand("register-before-remove-failure", "client-a"));
+        await session.DispatchAsync(CreateAddItemCommand("add-before-remove-failure", 49, "Galaxy.Tag.Value"));
+
+        MxCommandReply reply = await session.DispatchAsync(CreateRemoveItemCommand(
+            "remove-item-failure",
+            999,
+            504));
+
+        Assert.Equal(ProtocolStatusCode.MxaccessFailure, reply.ProtocolStatus.Code);
+        Assert.True(reply.HasHresult);
+        Assert.Equal(hresult, reply.Hresult);
+        Assert.Contains("0x80070057", reply.DiagnosticMessage);
+        Assert.Equal(999, fakeComObject.RemoveItemServerHandle);
+        Assert.Equal(504, fakeComObject.RemovedItemHandle);
+
+        RegisteredItemHandle registeredItemHandle = Assert.Single(
+            await session.GetRegisteredItemHandlesAsync());
+        Assert.Equal(49, registeredItemHandle.ServerHandle);
+        Assert.Equal(504, registeredItemHandle.ItemHandle);
+    }
+
+    [Fact]
+    public async Task DispatchAsync_AddItem2WhenMxAccessThrows_PreservesHResultAndDoesNotTrackItemHandle()
+    {
+        const int hresult = unchecked((int)0x80070057);
+        FakeMxAccessComObject fakeComObject = new(
+            registerHandle: 50,
+            addItem2Exception: new COMException("Invalid server handle.", hresult));
+        FakeMxAccessComObjectFactory factory = new(fakeComObject);
+        using StaRuntime runtime = CreateRuntime();
+        using MxAccessStaSession session = new(runtime, factory, new NoopEventSink());
+        await session.StartAsync(workerProcessId: 1234);
+
+        MxCommandReply reply = await session.DispatchAsync(CreateAddItem2Command(
+            "add-item2-failure",
+            9001,
+            "TestInt",
+            "TestChildObject"));
+
+        Assert.Equal(ProtocolStatusCode.MxaccessFailure, reply.ProtocolStatus.Code);
+        Assert.True(reply.HasHresult);
+        Assert.Equal(hresult, reply.Hresult);
+        Assert.Contains("0x80070057", reply.DiagnosticMessage);
+        Assert.Equal(9001, fakeComObject.AddItem2ServerHandle);
+        Assert.Equal("TestInt", fakeComObject.AddItem2Definition);
+        Assert.Equal("TestChildObject", fakeComObject.AddItem2Context);
+        Assert.Empty(await session.GetRegisteredItemHandlesAsync());
+    }
+
+    [Fact]
+    public async Task DispatchAsync_RegisterWithoutPayload_ReturnsInvalidRequest()
+    {
+        FakeMxAccessComObjectFactory factory = new(new FakeMxAccessComObject(registerHandle: 45));
+        using StaRuntime runtime = CreateRuntime();
+        using MxAccessStaSession session = new(runtime, factory, new NoopEventSink());
+        await session.StartAsync(workerProcessId: 1234);
+
+        MxCommandReply reply = await session.DispatchAsync(new StaCommand(
+            "session-1",
+            "missing-payload",
+            new MxCommand
+            {
+                Kind = MxCommandKind.Register,
+            }));
+
+        Assert.Equal(ProtocolStatusCode.InvalidRequest, reply.ProtocolStatus.Code);
+        Assert.Null(factory.FakeComObject.RegisteredClientName);
+    }
+
+    [Fact]
+    public async Task DispatchAsync_AddItemWithoutPayload_ReturnsInvalidRequest()
+    {
+        FakeMxAccessComObjectFactory factory = new(new FakeMxAccessComObject(registerHandle: 51));
+        using StaRuntime runtime = CreateRuntime();
+        using MxAccessStaSession session = new(runtime, factory, new NoopEventSink());
+        await session.StartAsync(workerProcessId: 1234);
+
+        MxCommandReply reply = await session.DispatchAsync(new StaCommand(
+            "session-1",
+            "missing-add-payload",
+            new MxCommand
+            {
+                Kind = MxCommandKind.AddItem,
+            }));
+
+        Assert.Equal(ProtocolStatusCode.InvalidRequest, reply.ProtocolStatus.Code);
+        Assert.Null(factory.FakeComObject.AddItemDefinition);
+    }
+
+    private static StaCommand CreateRegisterCommand(
+        string correlationId,
+        string clientName)
+    {
+        return new StaCommand(
+            "session-1",
+            correlationId,
+            new MxCommand
+            {
+                Kind = MxCommandKind.Register,
+                Register = new RegisterCommand
+                {
+                    ClientName = clientName,
+                },
+            });
+    }
+
+    private static StaCommand CreateUnregisterCommand(
+        string correlationId,
+        int serverHandle)
+    {
+        return new StaCommand(
+            "session-1",
+            correlationId,
+            new MxCommand
+            {
+                Kind = MxCommandKind.Unregister,
+                Unregister = new UnregisterCommand
+                {
+                    ServerHandle = serverHandle,
+                },
+            });
+    }
+
+    private static StaCommand CreateAddItemCommand(
+        string correlationId,
+        int serverHandle,
+        string itemDefinition)
+    {
+        return new StaCommand(
+            "session-1",
+            correlationId,
+            new MxCommand
+            {
+                Kind = MxCommandKind.AddItem,
+                AddItem = new AddItemCommand
+                {
+                    ServerHandle = serverHandle,
+                    ItemDefinition = itemDefinition,
+                },
+            });
+    }
+
+    private static StaCommand CreateAddItem2Command(
+        string correlationId,
+        int serverHandle,
+        string itemDefinition,
+        string itemContext)
+    {
+        return new StaCommand(
+            "session-1",
+            correlationId,
+            new MxCommand
+            {
+                Kind = MxCommandKind.AddItem2,
+                AddItem2 = new AddItem2Command
+                {
+                    ServerHandle = serverHandle,
+                    ItemDefinition = itemDefinition,
+                    ItemContext = itemContext,
+                },
+            });
+    }
+
+    private static StaCommand CreateRemoveItemCommand(
+        string correlationId,
+        int serverHandle,
+        int itemHandle)
+    {
+        return new StaCommand(
+            "session-1",
+            correlationId,
+            new MxCommand
+            {
+                Kind = MxCommandKind.RemoveItem,
+                RemoveItem = new RemoveItemCommand
+                {
+                    ServerHandle = serverHandle,
+                    ItemHandle = itemHandle,
+                },
+            });
+    }
+
+    private static StaRuntime CreateRuntime()
+    {
+        return new StaRuntime(
+            new NoopComApartmentInitializer(),
+            new StaMessagePump(),
+            TimeSpan.FromMilliseconds(25));
+    }
+
+    private sealed class FakeMxAccessComObject
+    {
+        private readonly int registerHandle;
+        private readonly int addItemHandle;
+        private readonly int addItem2Handle;
+        private readonly Exception? unregisterException;
+        private readonly Exception? addItemException;
+        private readonly Exception? addItem2Exception;
+        private readonly Exception? removeItemException;
+
+        public FakeMxAccessComObject(
+            int registerHandle,
+            int addItemHandle = 0,
+            int addItem2Handle = 0,
+            Exception? unregisterException = null,
+            Exception? addItemException = null,
+            Exception? addItem2Exception = null,
+            Exception? removeItemException = null)
+        {
+            this.registerHandle = registerHandle;
+            this.addItemHandle = addItemHandle;
+            this.addItem2Handle = addItem2Handle;
+            this.unregisterException = unregisterException;
+            this.addItemException = addItemException;
+            this.addItem2Exception = addItem2Exception;
+            this.removeItemException = removeItemException;
+        }
+
+        public string? RegisteredClientName { get; private set; }
+
+        public int? RegisterThreadId { get; private set; }
+
+        public int? UnregisteredServerHandle { get; private set; }
+
+        public int? UnregisterThreadId { get; private set; }
+
+        public int? AddItemServerHandle { get; private set; }
+
+        public string? AddItemDefinition { get; private set; }
+
+        public int? AddItemThreadId { get; private set; }
+
+        public int? AddItem2ServerHandle { get; private set; }
+
+        public string? AddItem2Definition { get; private set; }
+
+        public string? AddItem2Context { get; private set; }
+
+        public int? AddItem2ThreadId { get; private set; }
+
+        public int? RemoveItemServerHandle { get; private set; }
+
+        public int? RemovedItemHandle { get; private set; }
+
+        public int? RemoveItemThreadId { get; private set; }
+
+        public int Register(string clientName)
+        {
+            RegisteredClientName = clientName;
+            RegisterThreadId = Environment.CurrentManagedThreadId;
+
+            return registerHandle;
+        }
+
+        public void Unregister(int serverHandle)
+        {
+            UnregisteredServerHandle = serverHandle;
+            UnregisterThreadId = Environment.CurrentManagedThreadId;
+
+            if (unregisterException is not null)
+            {
+                throw unregisterException;
+            }
+        }
+
+        public int AddItem(
+            int serverHandle,
+            string itemDefinition)
+        {
+            AddItemServerHandle = serverHandle;
+            AddItemDefinition = itemDefinition;
+            AddItemThreadId = Environment.CurrentManagedThreadId;
+
+            if (addItemException is not null)
+            {
+                throw addItemException;
+            }
+
+            return addItemHandle;
+        }
+
+        public int AddItem2(
+            int serverHandle,
+            string itemDefinition,
+            string itemContext)
+        {
+            AddItem2ServerHandle = serverHandle;
+            AddItem2Definition = itemDefinition;
+            AddItem2Context = itemContext;
+            AddItem2ThreadId = Environment.CurrentManagedThreadId;
+
+            if (addItem2Exception is not null)
+            {
+                throw addItem2Exception;
+            }
+
+            return addItem2Handle;
+        }
+
+        public void RemoveItem(
+            int serverHandle,
+            int itemHandle)
+        {
+            RemoveItemServerHandle = serverHandle;
+            RemovedItemHandle = itemHandle;
+            RemoveItemThreadId = Environment.CurrentManagedThreadId;
+
+            if (removeItemException is not null)
+            {
+                throw removeItemException;
+            }
+        }
+    }
+
+    private sealed class FakeMxAccessComObjectFactory : IMxAccessComObjectFactory
+    {
+        public FakeMxAccessComObjectFactory(FakeMxAccessComObject fakeComObject)
+        {
+            FakeComObject = fakeComObject;
+        }
+
+        public FakeMxAccessComObject FakeComObject { get; }
+
+        public object Create()
+        {
+            return FakeComObject;
+        }
+    }
+
+    private sealed class NoopEventSink : IMxAccessEventSink
+    {
+        public void Attach(object mxAccessComObject)
+        {
+        }
+
+        public void Detach()
+        {
+        }
+    }
+
+    private sealed class NoopComApartmentInitializer : IStaComApartmentInitializer
+    {
+        public void Initialize()
+        {
+        }
+
+        public void Uninitialize()
+        {
+        }
+    }
+}

src/MxGateway.Worker.Tests/MxAccess/MxAccessLiveComCreationTests.cs

@@ -1,11 +1,18 @@
 using System;
 using System.Threading.Tasks;
+using MxGateway.Contracts.Proto;
 using MxGateway.Worker.MxAccess;
+using MxGateway.Worker.Sta;
 
 namespace MxGateway.Worker.Tests.MxAccess;
 
 public sealed class MxAccessLiveComCreationTests
 {
+    private const string LiveClientName = "MxGateway.Worker.Tests";
+    private const string DefaultLiveAddItemReference = "TestChildObject.TestInt";
+    private const string DefaultLiveAddItem2Definition = "TestInt";
+    private const string DefaultLiveAddItem2Context = "TestChildObject";
+
     [Fact]
     public async Task StartAsync_WhenOptedIn_CreatesInstalledMxAccessComObjectOnSta()
     {
@@ -21,4 +28,249 @@ public sealed class MxAccessLiveComCreationTests
 
         await session.StartAsync(workerProcessId: 1234);
     }
+
+    [Fact]
+    public async Task RegisterAndUnregister_WhenOptedIn_RoundTripsInstalledMxAccessServerHandle()
+    {
+        if (!RunLiveMxAccessTests())
+        {
+            return;
+        }
+
+        using MxAccessStaSession session = new();
+        await session.StartAsync(workerProcessId: 1234);
+
+        MxCommandReply registerReply = await session.DispatchAsync(new StaCommand(
+            "session-1",
+            "live-register",
+            new MxCommand
+            {
+                Kind = MxCommandKind.Register,
+                Register = new RegisterCommand
+                {
+                    ClientName = LiveClientName,
+                },
+            }));
+
+        Assert.Equal(ProtocolStatusCode.Ok, registerReply.ProtocolStatus.Code);
+        Assert.True(registerReply.Register.ServerHandle > 0);
+
+        MxCommandReply unregisterReply = await session.DispatchAsync(new StaCommand(
+            "session-1",
+            "live-unregister",
+            new MxCommand
+            {
+                Kind = MxCommandKind.Unregister,
+                Unregister = new UnregisterCommand
+                {
+                    ServerHandle = registerReply.Register.ServerHandle,
+                },
+            }));
+
+        Assert.Equal(ProtocolStatusCode.Ok, unregisterReply.ProtocolStatus.Code);
+    }
+
+    [Fact]
+    public async Task AddItemAndRemoveItem_WhenOptedIn_RoundTripsInstalledMxAccessItemHandle()
+    {
+        if (!RunLiveMxAccessTests())
+        {
+            return;
+        }
+
+        using MxAccessStaSession session = new();
+        await session.StartAsync(workerProcessId: 1234);
+
+        MxCommandReply registerReply = await RegisterLiveSessionAsync(session, "live-add-register");
+        int serverHandle = registerReply.Register.ServerHandle;
+        int itemHandle = 0;
+
+        try
+        {
+            MxCommandReply addItemReply = await session.DispatchAsync(new StaCommand(
+                "session-1",
+                "live-add-item",
+                new MxCommand
+                {
+                    Kind = MxCommandKind.AddItem,
+                    AddItem = new AddItemCommand
+                    {
+                        ServerHandle = serverHandle,
+                        ItemDefinition = GetLiveAddItemReference(),
+                    },
+                }));
+
+            Assert.Equal(ProtocolStatusCode.Ok, addItemReply.ProtocolStatus.Code);
+            Assert.True(addItemReply.AddItem.ItemHandle > 0);
+            itemHandle = addItemReply.AddItem.ItemHandle;
+
+            MxCommandReply removeItemReply = await session.DispatchAsync(new StaCommand(
+                "session-1",
+                "live-remove-item",
+                new MxCommand
+                {
+                    Kind = MxCommandKind.RemoveItem,
+                    RemoveItem = new RemoveItemCommand
+                    {
+                        ServerHandle = serverHandle,
+                        ItemHandle = itemHandle,
+                    },
+                }));
+
+            Assert.Equal(ProtocolStatusCode.Ok, removeItemReply.ProtocolStatus.Code);
+            itemHandle = 0;
+        }
+        finally
+        {
+            if (itemHandle > 0)
+            {
+                await session.DispatchAsync(new StaCommand(
+                    "session-1",
+                    "live-remove-item-cleanup",
+                    new MxCommand
+                    {
+                        Kind = MxCommandKind.RemoveItem,
+                        RemoveItem = new RemoveItemCommand
+                        {
+                            ServerHandle = serverHandle,
+                            ItemHandle = itemHandle,
+                        },
+                    }));
+            }
+
+            await UnregisterLiveSessionAsync(session, serverHandle, "live-add-unregister");
+        }
+    }
+
+    [Fact]
+    public async Task AddItem2AndRemoveItem_WhenOptedIn_PreservesContextForInstalledMxAccess()
+    {
+        if (!RunLiveMxAccessTests())
+        {
+            return;
+        }
+
+        using MxAccessStaSession session = new();
+        await session.StartAsync(workerProcessId: 1234);
+
+        MxCommandReply registerReply = await RegisterLiveSessionAsync(session, "live-add2-register");
+        int serverHandle = registerReply.Register.ServerHandle;
+        int itemHandle = 0;
+
+        try
+        {
+            MxCommandReply addItem2Reply = await session.DispatchAsync(new StaCommand(
+                "session-1",
+                "live-add-item2",
+                new MxCommand
+                {
+                    Kind = MxCommandKind.AddItem2,
+                    AddItem2 = new AddItem2Command
+                    {
+                        ServerHandle = serverHandle,
+                        ItemDefinition = DefaultLiveAddItem2Definition,
+                        ItemContext = DefaultLiveAddItem2Context,
+                    },
+                }));
+
+            Assert.Equal(ProtocolStatusCode.Ok, addItem2Reply.ProtocolStatus.Code);
+            Assert.True(addItem2Reply.AddItem2.ItemHandle > 0);
+            itemHandle = addItem2Reply.AddItem2.ItemHandle;
+
+            MxCommandReply removeItemReply = await session.DispatchAsync(new StaCommand(
+                "session-1",
+                "live-remove-item2",
+                new MxCommand
+                {
+                    Kind = MxCommandKind.RemoveItem,
+                    RemoveItem = new RemoveItemCommand
+                    {
+                        ServerHandle = serverHandle,
+                        ItemHandle = itemHandle,
+                    },
+                }));
+
+            Assert.Equal(ProtocolStatusCode.Ok, removeItemReply.ProtocolStatus.Code);
+            itemHandle = 0;
+        }
+        finally
+        {
+            if (itemHandle > 0)
+            {
+                await session.DispatchAsync(new StaCommand(
+                    "session-1",
+                    "live-remove-item2-cleanup",
+                    new MxCommand
+                    {
+                        Kind = MxCommandKind.RemoveItem,
+                        RemoveItem = new RemoveItemCommand
+                        {
+                            ServerHandle = serverHandle,
+                            ItemHandle = itemHandle,
+                        },
+                    }));
+            }
+
+            await UnregisterLiveSessionAsync(session, serverHandle, "live-add2-unregister");
+        }
+    }
+
+    private static bool RunLiveMxAccessTests()
+    {
+        return string.Equals(
+            Environment.GetEnvironmentVariable("MXGATEWAY_RUN_LIVE_MXACCESS_TESTS"),
+            "1",
+            StringComparison.Ordinal);
+    }
+
+    private static string GetLiveAddItemReference()
+    {
+        string itemReference = Environment.GetEnvironmentVariable("MXGATEWAY_LIVE_MXACCESS_ITEM");
+
+        return string.IsNullOrWhiteSpace(itemReference)
+            ? DefaultLiveAddItemReference
+            : itemReference;
+    }
+
+    private static async Task<MxCommandReply> RegisterLiveSessionAsync(
+        MxAccessStaSession session,
+        string correlationId)
+    {
+        MxCommandReply reply = await session.DispatchAsync(new StaCommand(
+            "session-1",
+            correlationId,
+            new MxCommand
+            {
+                Kind = MxCommandKind.Register,
+                Register = new RegisterCommand
+                {
+                    ClientName = LiveClientName,
+                },
+            }));
+
+        Assert.Equal(ProtocolStatusCode.Ok, reply.ProtocolStatus.Code);
+        Assert.True(reply.Register.ServerHandle > 0);
+
+        return reply;
+    }
+
+    private static async Task UnregisterLiveSessionAsync(
+        MxAccessStaSession session,
+        int serverHandle,
+        string correlationId)
+    {
+        MxCommandReply unregisterReply = await session.DispatchAsync(new StaCommand(
+            "session-1",
+            correlationId,
+            new MxCommand
+            {
+                Kind = MxCommandKind.Unregister,
+                Unregister = new UnregisterCommand
+                {
+                    ServerHandle = serverHandle,
+                },
+            }));
+
+        Assert.Equal(ProtocolStatusCode.Ok, unregisterReply.ProtocolStatus.Code);
+    }
 }

src/MxGateway.Worker/MxAccess/IMxAccessServer.cs

@@ -0,0 +1,21 @@
+namespace MxGateway.Worker.MxAccess;
+
+public interface IMxAccessServer
+{
+    int Register(string clientName);
+
+    void Unregister(int serverHandle);
+
+    int AddItem(
+        int serverHandle,
+        string itemDefinition);
+
+    int AddItem2(
+        int serverHandle,
+        string itemDefinition,
+        string itemContext);
+
+    void RemoveItem(
+        int serverHandle,
+        int itemHandle);
+}

src/MxGateway.Worker/MxAccess/MxAccessComServer.cs

@@ -0,0 +1,97 @@
+using System;
+using System.Reflection;
+using System.Runtime.ExceptionServices;
+using ArchestrA.MxAccess;
+
+namespace MxGateway.Worker.MxAccess;
+
+public sealed class MxAccessComServer : IMxAccessServer
+{
+    private readonly object mxAccessComObject;
+
+    public MxAccessComServer(object mxAccessComObject)
+    {
+        this.mxAccessComObject = mxAccessComObject ?? throw new ArgumentNullException(nameof(mxAccessComObject));
+    }
+
+    public int Register(string clientName)
+    {
+        if (mxAccessComObject is ILMXProxyServer mxAccessServer)
+        {
+            return mxAccessServer.Register(clientName);
+        }
+
+        return (int)Invoke(nameof(Register), clientName);
+    }
+
+    public void Unregister(int serverHandle)
+    {
+        if (mxAccessComObject is ILMXProxyServer mxAccessServer)
+        {
+            mxAccessServer.Unregister(serverHandle);
+            return;
+        }
+
+        Invoke(nameof(Unregister), serverHandle);
+    }
+
+    public int AddItem(
+        int serverHandle,
+        string itemDefinition)
+    {
+        if (mxAccessComObject is ILMXProxyServer mxAccessServer)
+        {
+            return mxAccessServer.AddItem(serverHandle, itemDefinition);
+        }
+
+        return (int)Invoke(nameof(AddItem), serverHandle, itemDefinition);
+    }
+
+    public int AddItem2(
+        int serverHandle,
+        string itemDefinition,
+        string itemContext)
+    {
+        if (mxAccessComObject is ILMXProxyServer3 mxAccessServer)
+        {
+            return mxAccessServer.AddItem2(serverHandle, itemDefinition, itemContext);
+        }
+
+        return (int)Invoke(nameof(AddItem2), serverHandle, itemDefinition, itemContext);
+    }
+
+    public void RemoveItem(
+        int serverHandle,
+        int itemHandle)
+    {
+        if (mxAccessComObject is ILMXProxyServer mxAccessServer)
+        {
+            mxAccessServer.RemoveItem(serverHandle, itemHandle);
+            return;
+        }
+
+        Invoke(nameof(RemoveItem), serverHandle, itemHandle);
+    }
+
+    private object Invoke(
+        string methodName,
+        params object[] arguments)
+    {
+        try
+        {
+            return mxAccessComObject
+                .GetType()
+                .InvokeMember(
+                    methodName,
+                    BindingFlags.Instance | BindingFlags.Public | BindingFlags.InvokeMethod,
+                    binder: null,
+                    target: mxAccessComObject,
+                    args: arguments);
+        }
+        catch (TargetInvocationException exception) when (exception.InnerException is not null)
+        {
+            ExceptionDispatchInfo.Capture(exception.InnerException).Throw();
+            throw;
+        }
+    }
+}

src/MxGateway.Worker/MxAccess/MxAccessCommandExecutor.cs

@@ -0,0 +1,166 @@
+using System;
+using MxGateway.Contracts.Proto;
+using MxGateway.Worker.Conversion;
+using MxGateway.Worker.Sta;
+
+namespace MxGateway.Worker.MxAccess;
+
+public sealed class MxAccessCommandExecutor : IStaCommandExecutor
+{
+    private readonly MxAccessSession session;
+    private readonly VariantConverter variantConverter;
+
+    public MxAccessCommandExecutor(MxAccessSession session)
+        : this(session, new VariantConverter())
+    {
+    }
+
+    public MxAccessCommandExecutor(
+        MxAccessSession session,
+        VariantConverter variantConverter)
+    {
+        this.session = session ?? throw new ArgumentNullException(nameof(session));
+        this.variantConverter = variantConverter ?? throw new ArgumentNullException(nameof(variantConverter));
+    }
+
+    public MxCommandReply Execute(StaCommand command)
+    {
+        if (command is null)
+        {
+            throw new ArgumentNullException(nameof(command));
+        }
+
+        return command.Kind switch
+        {
+            MxCommandKind.Register => ExecuteRegister(command),
+            MxCommandKind.Unregister => ExecuteUnregister(command),
+            MxCommandKind.AddItem => ExecuteAddItem(command),
+            MxCommandKind.AddItem2 => ExecuteAddItem2(command),
+            MxCommandKind.RemoveItem => ExecuteRemoveItem(command),
+            _ => CreateInvalidRequestReply(command, $"Unsupported MXAccess command kind {command.Kind}."),
+        };
+    }
+
+    private MxCommandReply ExecuteRegister(StaCommand command)
+    {
+        if (command.Command.PayloadCase != MxCommand.PayloadOneofCase.Register)
+        {
+            return CreateInvalidRequestReply(command, "Register command payload is required.");
+        }
+
+        int serverHandle = session.Register(command.Command.Register.ClientName);
+        MxCommandReply reply = CreateOkReply(command);
+        reply.ReturnValue = variantConverter.Convert(serverHandle);
+        reply.Register = new RegisterReply
+        {
+            ServerHandle = serverHandle,
+        };
+
+        return reply;
+    }
+
+    private MxCommandReply ExecuteUnregister(StaCommand command)
+    {
+        if (command.Command.PayloadCase != MxCommand.PayloadOneofCase.Unregister)
+        {
+            return CreateInvalidRequestReply(command, "Unregister command payload is required.");
+        }
+
+        session.Unregister(command.Command.Unregister.ServerHandle);
+        return CreateOkReply(command);
+    }
+
+    private MxCommandReply ExecuteAddItem(StaCommand command)
+    {
+        if (command.Command.PayloadCase != MxCommand.PayloadOneofCase.AddItem)
+        {
+            return CreateInvalidRequestReply(command, "AddItem command payload is required.");
+        }
+
+        AddItemCommand addItemCommand = command.Command.AddItem;
+        int itemHandle = session.AddItem(
+            addItemCommand.ServerHandle,
+            addItemCommand.ItemDefinition);
+
+        MxCommandReply reply = CreateOkReply(command);
+        reply.ReturnValue = variantConverter.Convert(itemHandle);
+        reply.AddItem = new AddItemReply
+        {
+            ItemHandle = itemHandle,
+        };
+
+        return reply;
+    }
+
+    private MxCommandReply ExecuteAddItem2(StaCommand command)
+    {
+        if (command.Command.PayloadCase != MxCommand.PayloadOneofCase.AddItem2)
+        {
+            return CreateInvalidRequestReply(command, "AddItem2 command payload is required.");
+        }
+
+        AddItem2Command addItem2Command = command.Command.AddItem2;
+        int itemHandle = session.AddItem2(
+            addItem2Command.ServerHandle,
+            addItem2Command.ItemDefinition,
+            addItem2Command.ItemContext);
+
+        MxCommandReply reply = CreateOkReply(command);
+        reply.ReturnValue = variantConverter.Convert(itemHandle);
+        reply.AddItem2 = new AddItem2Reply
+        {
+            ItemHandle = itemHandle,
+        };
+
+        return reply;
+    }
+
+    private MxCommandReply ExecuteRemoveItem(StaCommand command)
+    {
+        if (command.Command.PayloadCase != MxCommand.PayloadOneofCase.RemoveItem)
+        {
+            return CreateInvalidRequestReply(command, "RemoveItem command payload is required.");
+        }
+
+        RemoveItemCommand removeItemCommand = command.Command.RemoveItem;
+        session.RemoveItem(
+            removeItemCommand.ServerHandle,
+            removeItemCommand.ItemHandle);
+
+        return CreateOkReply(command);
+    }
+
+    private static MxCommandReply CreateOkReply(StaCommand command)
+    {
+        return new MxCommandReply
+        {
+            SessionId = command.SessionId,
+            CorrelationId = command.CorrelationId,
+            Kind = command.Kind,
+            Hresult = 0,
+            ProtocolStatus = new ProtocolStatus
+            {
+                Code = ProtocolStatusCode.Ok,
+                Message = "OK",
+            },
+        };
+    }
+
+    private static MxCommandReply CreateInvalidRequestReply(
+        StaCommand command,
+        string message)
+    {
+        return new MxCommandReply
+        {
+            SessionId = command.SessionId,
+            CorrelationId = command.CorrelationId,
+            Kind = command.Kind,
+            ProtocolStatus = new ProtocolStatus
+            {
+                Code = ProtocolStatusCode.InvalidRequest,
+                Message = message,
+            },
+            DiagnosticMessage = message,
+        };
+    }
+}

src/MxGateway.Worker/MxAccess/MxAccessHandleRegistry.cs

@@ -0,0 +1,82 @@
+using System.Collections.Generic;
+using System.Linq;
+
+namespace MxGateway.Worker.MxAccess;
+
+public sealed class MxAccessHandleRegistry
+{
+    private readonly Dictionary<int, RegisteredServerHandle> serverHandles = new();
+    private readonly Dictionary<long, RegisteredItemHandle> itemHandles = new();
+
+    public IReadOnlyList<RegisteredServerHandle> ServerHandles => serverHandles
+        .Values
+        .OrderBy(handle => handle.ServerHandle)
+        .ToArray();
+
+    public IReadOnlyList<RegisteredItemHandle> ItemHandles => itemHandles
+        .Values
+        .OrderBy(handle => handle.ServerHandle)
+        .ThenBy(handle => handle.ItemHandle)
+        .ToArray();
+
+    public void RegisterServerHandle(
+        int serverHandle,
+        string clientName)
+    {
+        serverHandles[serverHandle] = new RegisteredServerHandle(serverHandle, clientName);
+    }
+
+    public void UnregisterServerHandle(int serverHandle)
+    {
+        serverHandles.Remove(serverHandle);
+
+        foreach (long key in itemHandles
+            .Where(pair => pair.Value.ServerHandle == serverHandle)
+            .Select(pair => pair.Key)
+            .ToArray())
+        {
+            itemHandles.Remove(key);
+        }
+    }
+
+    public bool ContainsServerHandle(int serverHandle)
+    {
+        return serverHandles.ContainsKey(serverHandle);
+    }
+
+    public void RegisterItemHandle(
+        int serverHandle,
+        int itemHandle,
+        string itemDefinition,
+        string itemContext,
+        bool hasItemContext)
+    {
+        itemHandles[CreateItemKey(serverHandle, itemHandle)] = new RegisteredItemHandle(
+            serverHandle,
+            itemHandle,
+            itemDefinition,
+            itemContext,
+            hasItemContext);
+    }
+
+    public void RemoveItemHandle(
+        int serverHandle,
+        int itemHandle)
+    {
+        itemHandles.Remove(CreateItemKey(serverHandle, itemHandle));
+    }
+
+    public bool ContainsItemHandle(
+        int serverHandle,
+        int itemHandle)
+    {
+        return itemHandles.ContainsKey(CreateItemKey(serverHandle, itemHandle));
+    }
+
+    private static long CreateItemKey(
+        int serverHandle,
+        int itemHandle)
+    {
+        return ((long)serverHandle << 32) | (uint)itemHandle;
+    }
+}

src/MxGateway.Worker/MxAccess/MxAccessSession.cs

@@ -8,21 +8,29 @@ namespace MxGateway.Worker.MxAccess;
 public sealed class MxAccessSession : IDisposable
 {
     private readonly object mxAccessComObject;
+    private readonly IMxAccessServer mxAccessServer;
     private readonly IMxAccessEventSink eventSink;
+    private readonly MxAccessHandleRegistry handleRegistry;
     private bool disposed;
 
     private MxAccessSession(
         object mxAccessComObject,
+        IMxAccessServer mxAccessServer,
         IMxAccessEventSink eventSink,
+        MxAccessHandleRegistry handleRegistry,
         int creationThreadId)
     {
         this.mxAccessComObject = mxAccessComObject ?? throw new ArgumentNullException(nameof(mxAccessComObject));
+        this.mxAccessServer = mxAccessServer ?? throw new ArgumentNullException(nameof(mxAccessServer));
         this.eventSink = eventSink ?? throw new ArgumentNullException(nameof(eventSink));
+        this.handleRegistry = handleRegistry ?? throw new ArgumentNullException(nameof(handleRegistry));
         CreationThreadId = creationThreadId;
     }
 
     public int CreationThreadId { get; }
 
+    public MxAccessHandleRegistry HandleRegistry => handleRegistry;
+
     public WorkerReady CreateWorkerReady(int workerProcessId)
     {
         return new WorkerReady
@@ -62,7 +70,9 @@ public sealed class MxAccessSession : IDisposable
 
             return new MxAccessSession(
                 mxAccessComObject,
+                new MxAccessComServer(mxAccessComObject),
                 eventSink,
+                new MxAccessHandleRegistry(),
                 Environment.CurrentManagedThreadId);
         }
         catch (Exception exception)
@@ -78,6 +88,69 @@ public sealed class MxAccessSession : IDisposable
         }
     }
 
+    public int Register(string clientName)
+    {
+        ThrowIfDisposed();
+
+        int serverHandle = mxAccessServer.Register(clientName);
+        handleRegistry.RegisterServerHandle(serverHandle, clientName);
+
+        return serverHandle;
+    }
+
+    public void Unregister(int serverHandle)
+    {
+        ThrowIfDisposed();
+
+        mxAccessServer.Unregister(serverHandle);
+        handleRegistry.UnregisterServerHandle(serverHandle);
+    }
+
+    public int AddItem(
+        int serverHandle,
+        string itemDefinition)
+    {
+        ThrowIfDisposed();
+
+        int itemHandle = mxAccessServer.AddItem(serverHandle, itemDefinition);
+        handleRegistry.RegisterItemHandle(
+            serverHandle,
+            itemHandle,
+            itemDefinition,
+            string.Empty,
+            hasItemContext: false);
+
+        return itemHandle;
+    }
+
+    public int AddItem2(
+        int serverHandle,
+        string itemDefinition,
+        string itemContext)
+    {
+        ThrowIfDisposed();
+
+        int itemHandle = mxAccessServer.AddItem2(serverHandle, itemDefinition, itemContext);
+        handleRegistry.RegisterItemHandle(
+            serverHandle,
+            itemHandle,
+            itemDefinition,
+            itemContext,
+            hasItemContext: true);
+
+        return itemHandle;
+    }
+
+    public void RemoveItem(
+        int serverHandle,
+        int itemHandle)
+    {
+        ThrowIfDisposed();
+
+        mxAccessServer.RemoveItem(serverHandle, itemHandle);
+        handleRegistry.RemoveItemHandle(serverHandle, itemHandle);
+    }
+
     public void Dispose()
     {
         if (disposed)
@@ -94,4 +167,12 @@ public sealed class MxAccessSession : IDisposable
 
         disposed = true;
     }
+
+    private void ThrowIfDisposed()
+    {
+        if (disposed)
+        {
+            throw new ObjectDisposedException(nameof(MxAccessSession));
+        }
+    }
 }

src/MxGateway.Worker/MxAccess/MxAccessStaSession.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.Threading;
 using System.Threading.Tasks;
 using MxGateway.Contracts.Proto;
@@ -11,6 +12,7 @@ public sealed class MxAccessStaSession : IDisposable
     private readonly IMxAccessComObjectFactory factory;
     private readonly IMxAccessEventSink eventSink;
     private readonly StaRuntime staRuntime;
+    private StaCommandDispatcher? commandDispatcher;
     private MxAccessSession? session;
     private bool disposed;
 
@@ -47,11 +49,51 @@ public sealed class MxAccessStaSession : IDisposable
                 }
 
                 session = MxAccessSession.Create(factory, eventSink);
+                commandDispatcher = new StaCommandDispatcher(
+                    staRuntime,
+                    new MxAccessCommandExecutor(session));
+
                 return session.CreateWorkerReady(workerProcessId);
             },
             cancellationToken);
     }
 
+    public Task<MxCommandReply> DispatchAsync(StaCommand command)
+    {
+        if (commandDispatcher is null)
+        {
+            throw new InvalidOperationException("MXAccess COM session has not been started.");
+        }
+
+        return commandDispatcher.DispatchAsync(command);
+    }
+
+    public Task<IReadOnlyList<RegisteredServerHandle>> GetRegisteredServerHandlesAsync(
+        CancellationToken cancellationToken = default)
+    {
+        if (session is null)
+        {
+            throw new InvalidOperationException("MXAccess COM session has not been started.");
+        }
+
+        return staRuntime.InvokeAsync(
+            () => session.HandleRegistry.ServerHandles,
+            cancellationToken);
+    }
+
+    public Task<IReadOnlyList<RegisteredItemHandle>> GetRegisteredItemHandlesAsync(
+        CancellationToken cancellationToken = default)
+    {
+        if (session is null)
+        {
+            throw new InvalidOperationException("MXAccess COM session has not been started.");
+        }
+
+        return staRuntime.InvokeAsync(
+            () => session.HandleRegistry.ItemHandles,
+            cancellationToken);
+    }
+
     public void Dispose()
     {
         if (disposed)
@@ -59,6 +101,8 @@ public sealed class MxAccessStaSession : IDisposable
             return;
         }
 
+        commandDispatcher?.RequestShutdown();
+
         if (session is not null)
         {
             staRuntime.InvokeAsync(() => session.Dispose()).GetAwaiter().GetResult();

src/MxGateway.Worker/MxAccess/RegisteredItemHandle.cs

@@ -0,0 +1,28 @@
+namespace MxGateway.Worker.MxAccess;
+
+public sealed class RegisteredItemHandle
+{
+    public RegisteredItemHandle(
+        int serverHandle,
+        int itemHandle,
+        string itemDefinition,
+        string itemContext,
+        bool hasItemContext)
+    {
+        ServerHandle = serverHandle;
+        ItemHandle = itemHandle;
+        ItemDefinition = itemDefinition;
+        ItemContext = itemContext;
+        HasItemContext = hasItemContext;
+    }
+
+    public int ServerHandle { get; }
+
+    public int ItemHandle { get; }
+
+    public string ItemDefinition { get; }
+
+    public string ItemContext { get; }
+
+    public bool HasItemContext { get; }
+}

src/MxGateway.Worker/MxAccess/RegisteredServerHandle.cs

@@ -0,0 +1,16 @@
+namespace MxGateway.Worker.MxAccess;
+
+public sealed class RegisteredServerHandle
+{
+    public RegisteredServerHandle(
+        int serverHandle,
+        string clientName)
+    {
+        ServerHandle = serverHandle;
+        ClientName = clientName;
+    }
+
+    public int ServerHandle { get; }
+
+    public string ClientName { get; }
+}