Implement worker heartbeat watchdog

docs/GatewayTesting.md

@@ -18,6 +18,7 @@ starting `MxGateway.Worker.exe` or loading MXAccess COM. The harness scripts:
 - `WorkerHello` and `WorkerReady` startup,
 - command replies with matching correlation ids,
 - ordered `WorkerEvent` frames,
+- `WorkerHeartbeat` frames,
 - `WorkerFault` frames,
 - shutdown acknowledgements,
 - malformed protobuf payloads and oversized frame headers,
@@ -43,6 +44,8 @@ event streaming behavior:
 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
+dotnet test src/MxGateway.Tests/MxGateway.Tests.csproj --filter FullyQualifiedName~WorkerClientTests
+dotnet test src/MxGateway.Worker.Tests/MxGateway.Worker.Tests.csproj -p:Platform=x86 --filter FullyQualifiedName~WorkerPipeSessionTests
 ```
 
 Run the gateway test project after shared gateway test infrastructure changes:

docs/gateway-dashboard-design.md

@@ -34,13 +34,9 @@ SignalR circuit. Bootstrap is sufficient for a basic dashboard.
 
 ## Hosting Model
 
-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.
+The dashboard is hosted by `MxGateway.Server` alongside the gRPC API.
 
-Endpoint layout:
+Suggested endpoint layout:
 
 ```text
 /dashboard
@@ -49,7 +45,7 @@ Endpoint layout:
 /dashboard/workers
 /dashboard/events
 /dashboard/settings
-/dashboard/_blazor
+/_blazor
 ```
 
 The app should redirect `/` to `/dashboard` only if the deployment wants the
@@ -63,10 +59,9 @@ MxGateway.Server
     Components/
       App.razor
       Routes.razor
-      DashboardPageBase.cs
-      DashboardDisplay.cs
       Layout/
         DashboardLayout.razor
+        NavMenu.razor
       Pages/
         DashboardHome.razor
         SessionsPage.razor
@@ -74,21 +69,26 @@ MxGateway.Server
         WorkersPage.razor
         EventsPage.razor
         SettingsPage.razor
-      Shared/
+      Components/
         MetricCard.razor
-        StatusBadge.razor
+        SessionTable.razor
+        WorkerTable.razor
+        EventRatePanel.razor
         FaultList.razor
+    Services/
       DashboardSnapshotService.cs
-    DashboardAuthorizationHandler.cs
-    DashboardAuthenticator.cs
+      DashboardUpdateHub.cs
+      DashboardAuthorization.cs
+    Models/
       DashboardSnapshot.cs
-    DashboardSessionSummary.cs
-    DashboardWorkerSummary.cs
-    DashboardMetricSummary.cs
+      SessionSummary.cs
+      WorkerSummary.cs
+      MetricSummary.cs
 ```
 
-Blazor Server provides the SignalR circuit for UI updates. The implementation
-does not add a separate public dashboard hub.
+`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.
 
 ## Dashboard Data Source
 
@@ -137,7 +137,7 @@ gateway internals.
 
 Use Blazor Server component state updates for real-time dashboard refresh.
 
-Implemented pattern:
+Recommended pattern:
 
 1. Page/component subscribes to `WatchSnapshotsAsync`.
 2. Snapshot service emits updates from a bounded channel or timer.
@@ -147,8 +147,10 @@ Implemented pattern:
 
 Default update cadence:
 
+- immediate update on session create/close/fault,
+- immediate update on worker fault,
 - periodic metrics refresh every 1 second,
-- event counters update on the next snapshot tick.
+- event-rate windows updated every 1 second.
 
 Avoid pushing every MXAccess data-change event to the dashboard. Aggregate event
 counts and rates instead.
@@ -318,9 +320,7 @@ Suggested configuration:
 
 ## Styling
 
-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`.
+Use Bootstrap utility classes and a small local stylesheet.
 
 Recommended visual language:
 
@@ -361,18 +361,15 @@ Integration tests should verify:
 
 ## Initial Implementation Slice
 
-The first dashboard slice implements:
+The first dashboard slice should implement:
 
 1. Blazor Server hosting in `MxGateway.Server`.
-2. local Bootstrap static assets.
+2. 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 and session details.
+7. sessions page with active session table.
 8. workers page with worker table.
-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.
+9. 1-second realtime refresh through Blazor Server.
+10. redaction tests for secrets.

docs/mxaccess-worker-instance-design.md

@@ -576,13 +576,19 @@ Do not drop or coalesce events in v1.
 
 ## Heartbeat And Watchdog
 
-The worker heartbeat should prove that:
+`WorkerPipeSession` starts the heartbeat loop after the gateway validates
+`WorkerHello` and receives `WorkerReady`. Heartbeats continue until
+`WorkerShutdown`, cancellation, or a pipe/protocol failure stops the session.
+The loop uses `WorkerPipeSessionOptions.HeartbeatInterval`; the default matches
+the gateway worker heartbeat interval.
+
+The worker heartbeat proves that:
 
 - pipe writer is alive,
 - worker host is alive,
 - STA has recently pumped or completed work.
 
-Heartbeat payload should include:
+Heartbeat payload includes:
 
 - worker process id,
 - session id,
@@ -593,13 +599,19 @@ Heartbeat payload should include:
 - event sequence,
 - current command correlation id if any.
 
-The STA watchdog should warn when:
+`MxAccessStaSession.CaptureHeartbeat()` reads `StaRuntime.LastActivityUtc` and
+`StaCommandDispatcher` queue state without touching the raw MXAccess COM object
+outside the STA. Event queue depth and event sequence are reported as zero until
+the event queue implementation owns those counters.
 
-- one command exceeds its expected duration,
-- the STA has not pumped messages within the heartbeat grace period,
-- event queue depth remains high.
-
-The worker can report the problem, but the gateway owns the final kill decision.
+The STA watchdog currently emits a `WorkerFault` with
+`WorkerFaultCategory.StaHung` when `LastStaActivityUtc` is older than
+`WorkerPipeSessionOptions.HeartbeatGrace`. The fault includes the current
+command correlation id when a command is active. Command duration and high event
+queue depth remain observable through heartbeat fields until dedicated
+thresholds own those warnings. The worker reports stale STA activity, but the
+gateway owns the final kill decision through its existing heartbeat and worker
+lifecycle policy.
 
 ## Shutdown
 

gateway.md

@@ -109,22 +109,13 @@ 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.
+loopback requests only when explicitly enabled.
 
 ### Worker Process
 

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

@@ -1,34 +0,0 @@
-@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

@@ -1,30 +0,0 @@
-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

@@ -1,48 +0,0 @@
-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

@@ -1,53 +0,0 @@
-@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

@@ -1,37 +0,0 @@
-@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

@@ -1,64 +0,0 @@
-@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

@@ -1,69 +0,0 @@
-@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

@@ -1,67 +0,0 @@
-@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

@@ -1,47 +0,0 @@
-@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

@@ -1,53 +0,0 @@
-@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

@@ -1,15 +0,0 @@
-<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

@@ -1,39 +0,0 @@
-@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

@@ -1,21 +0,0 @@
-<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

@@ -1,15 +0,0 @@
-<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

@@ -1,12 +0,0 @@
-@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/DashboardEndpointRouteBuilderExtensions.cs

@@ -3,7 +3,6 @@ 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;
 
@@ -23,6 +22,13 @@ public static class DashboardEndpointRouteBuilderExtensions
         string pathBase = NormalizePathBase(dashboardSection["PathBase"] ?? new DashboardOptions().PathBase);
         RouteGroupBuilder dashboard = endpoints.MapGroup(pathBase);
 
+        dashboard.MapGet(
+                "/",
+                (HttpContext httpContext, IAntiforgery antiforgery, IDashboardSnapshotService snapshotService) =>
+                    GetDashboardHomeAsync(httpContext, antiforgery, snapshotService, pathBase))
+            .RequireAuthorization(DashboardAuthenticationDefaults.AuthorizationPolicy)
+            .WithName("DashboardHome");
+
         dashboard.MapGet(
                 "/login",
                 (HttpContext httpContext, IAntiforgery antiforgery) => GetLoginAsync(httpContext, antiforgery, pathBase))
@@ -48,13 +54,36 @@ public static class DashboardEndpointRouteBuilderExtensions
             .AllowAnonymous()
             .WithName("DashboardAccessDenied");
 
-        dashboard.MapRazorComponents<App>()
-            .AddInteractiveServerRenderMode()
-            .RequireAuthorization(DashboardAuthenticationDefaults.AuthorizationPolicy);
-
         return endpoints;
     }
 
+    private static ContentHttpResult GetDashboardHomeAsync(
+        HttpContext httpContext,
+        IAntiforgery antiforgery,
+        IDashboardSnapshotService snapshotService,
+        string pathBase)
+    {
+        AntiforgeryTokenSet tokens = antiforgery.GetAndStoreTokens(httpContext);
+        DashboardSnapshot snapshot = snapshotService.GetSnapshot();
+        string requestToken = tokens.RequestToken ?? string.Empty;
+        string body = $"""
+            <form method="post" action="{HtmlEncoder.Default.Encode(pathBase + "/logout")}" class="mb-3">
+                <input name="{tokens.FormFieldName}" type="hidden" value="{HtmlEncoder.Default.Encode(requestToken)}" />
+                <button type="submit">Sign out</button>
+            </form>
+            <dl>
+                <dt>Open sessions</dt>
+                <dd>{snapshot.Sessions.Count}</dd>
+                <dt>Workers</dt>
+                <dd>{snapshot.Workers.Count}</dd>
+                <dt>Faults</dt>
+                <dd>{snapshot.Faults.Count}</dd>
+            </dl>
+            """;
+
+        return TypedResults.Content(RenderPage("MXAccess Gateway Dashboard", body), "text/html");
+    }
+
     private static Task<ContentHttpResult> GetLoginAsync(
         HttpContext httpContext,
         IAntiforgery antiforgery,
@@ -130,20 +159,14 @@ public static class DashboardEndpointRouteBuilderExtensions
             : $"<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">
+            <form method="post" action="{HtmlEncoder.Default.Encode(pathBase + "/login")}">
                 <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>
+                <label for="apiKey">API key</label>
+                <input id="apiKey" name="apiKey" type="password" autocomplete="off" />
+                <button type="submit">Sign in</button>
             </form>
-            </section>
             """;
 
         return RenderPage("Dashboard Sign In", body);
@@ -158,15 +181,12 @@ public static class DashboardEndpointRouteBuilderExtensions
                 <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>
+                    <h1>{HtmlEncoder.Default.Encode(title)}</h1>
                     {body}
                 </main>
-                <script src="/lib/bootstrap/js/bootstrap.bundle.min.js"></script>
             </body>
             </html>
             """;

src/MxGateway.Server/Dashboard/DashboardServiceCollectionExtensions.cs

@@ -13,9 +13,6 @@ public static class DashboardServiceCollectionExtensions
         services.AddSingleton<IDashboardAuthenticator, DashboardAuthenticator>();
         services.AddHttpContextAccessor();
         services.AddAntiforgery();
-        services.AddCascadingAuthenticationState();
-        services.AddRazorComponents()
-            .AddInteractiveServerComponents();
         services
             .AddAuthentication(DashboardAuthenticationDefaults.AuthenticationScheme)
             .AddCookie(DashboardAuthenticationDefaults.AuthenticationScheme);

src/MxGateway.Server/GatewayApplication.cs

@@ -19,10 +19,8 @@ public static class GatewayApplication
         WebApplication app = builder.Build();
 
         app.UseGatewayRequestLoggingScope();
-        app.UseStaticFiles();
         app.UseAuthentication();
         app.UseAuthorization();
-        app.UseAntiforgery();
         app.MapGatewayEndpoints();
 
         return app;

src/MxGateway.Server/libman.json

@@ -1,14 +0,0 @@
-{
-  "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

@@ -1,138 +0,0 @@
-: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/GatewayApplicationTests.cs

@@ -33,37 +33,6 @@ 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",
@@ -96,12 +65,4 @@ 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/Workers/FakeWorkerHarnessTests.cs

@@ -105,6 +105,25 @@ public sealed class FakeWorkerHarnessTests
         Assert.Equal(WorkerClientState.Faulted, client.State);
     }
 
+    [Fact]
+    public async Task SendHeartbeatAsync_UpdatesClientHeartbeatState()
+    {
+        await using FakeWorkerHarness fakeWorker = await FakeWorkerHarness.CreateConnectedPairAsync();
+        await using WorkerClient client = fakeWorker.CreateClient();
+        await StartClientAsync(fakeWorker, client);
+        DateTimeOffset previousHeartbeat = client.LastHeartbeatAt;
+
+        await Task.Delay(TimeSpan.FromMilliseconds(20));
+        await fakeWorker.SendHeartbeatAsync(
+            configureHeartbeat: heartbeat => heartbeat.WorkerProcessId = 2468);
+
+        await WaitUntilAsync(
+            () => client.ProcessId == 2468 && client.LastHeartbeatAt > previousHeartbeat,
+            TestTimeout);
+
+        Assert.Equal(WorkerClientState.Ready, client.State);
+    }
+
     [Fact]
     public async Task InvokeAsync_WithHungWorker_TimesOutPendingCommand()
     {

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

@@ -284,6 +284,26 @@ public sealed class FakeWorkerHarness : IAsyncDisposable
             cancellationToken).ConfigureAwait(false);
     }
 
+    public async Task SendHeartbeatAsync(
+        WorkerState state = WorkerState.Ready,
+        CancellationToken cancellationToken = default,
+        Action<WorkerHeartbeat>? configureHeartbeat = null)
+    {
+        WorkerHeartbeat heartbeat = new()
+        {
+            WorkerProcessId = DefaultWorkerProcessId,
+            State = state,
+            LastStaActivityTimestamp = Timestamp.FromDateTimeOffset(DateTimeOffset.UtcNow),
+        };
+        configureHeartbeat?.Invoke(heartbeat);
+
+        await _writer.WriteAsync(
+            CreateEnvelope(
+                correlationId: string.Empty,
+                envelope => envelope.WorkerHeartbeat = heartbeat),
+            cancellationToken).ConfigureAwait(false);
+    }
+
     public async Task SendShutdownAckAsync(
         ProtocolStatusCode statusCode = ProtocolStatusCode.Ok,
         CancellationToken cancellationToken = default)

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

@@ -1,4 +1,5 @@
 using System.IO.Pipes;
+using Google.Protobuf.WellKnownTypes;
 using MxGateway.Contracts;
 using MxGateway.Contracts.Proto;
 using MxGateway.Server.Workers;
@@ -151,6 +152,24 @@ public sealed class WorkerClientTests
         Assert.Equal(WorkerClientState.Faulted, client.State);
     }
 
+    [Fact]
+    public async Task ReadLoop_WhenHeartbeatArrives_UpdatesLastHeartbeatAndWorkerProcess()
+    {
+        await using PipePair pipePair = await PipePair.CreateAsync();
+        await using WorkerClient client = CreateClient(pipePair);
+        await CompleteHandshakeAsync(client, pipePair);
+        DateTimeOffset previousHeartbeat = client.LastHeartbeatAt;
+
+        await Task.Delay(TimeSpan.FromMilliseconds(20));
+        await pipePair.WorkerWriter.WriteAsync(CreateHeartbeatEnvelope(workerProcessId: 9876));
+
+        await WaitUntilAsync(
+            () => client.ProcessId == 9876 && client.LastHeartbeatAt > previousHeartbeat,
+            TestTimeout);
+
+        Assert.Equal(WorkerClientState.Ready, client.State);
+    }
+
     [Fact]
     public async Task HeartbeatMonitor_WhenHeartbeatExpires_FaultsClient()
     {
@@ -276,6 +295,21 @@ public sealed class WorkerClientTests
             });
     }
 
+    private static WorkerEnvelope CreateHeartbeatEnvelope(int workerProcessId)
+    {
+        return CreateWorkerEnvelope(
+            correlationId: string.Empty,
+            sequence: 20,
+            envelope => envelope.WorkerHeartbeat = new WorkerHeartbeat
+            {
+                WorkerProcessId = workerProcessId,
+                State = WorkerState.Ready,
+                LastStaActivityTimestamp = Timestamp.FromDateTimeOffset(DateTimeOffset.UtcNow),
+                PendingCommandCount = 0,
+                OutboundEventQueueDepth = 0,
+            });
+    }
+
     private static WorkerEnvelope CreateWorkerEnvelope(
         string correlationId,
         ulong sequence,

src/MxGateway.Worker.Tests/Bootstrap/WorkerApplicationTests.cs

@@ -30,7 +30,7 @@ public sealed class WorkerApplicationTests
         Assert.Equal("mxaccess-gateway-123-session-1", entry.Fields["pipe_name"]);
         Assert.Equal(GatewayContractInfo.WorkerProtocolVersion, entry.Fields["protocol_version"]);
         Assert.Equal("[redacted]", entry.Fields["nonce"]);
-        Assert.Equal("WorkerPipeHandshakeSucceeded", logger.Entries[1].EventName);
+        Assert.Equal("WorkerPipeSessionCompleted", logger.Entries[1].EventName);
     }
 
     [Fact]

src/MxGateway.Worker.Tests/Ipc/WorkerPipeClientTests.cs

@@ -1,10 +1,15 @@
 using System;
+using System.IO;
 using System.IO.Pipes;
+using System.Threading;
 using System.Threading.Tasks;
+using Google.Protobuf.WellKnownTypes;
 using MxGateway.Contracts;
 using MxGateway.Contracts.Proto;
 using MxGateway.Worker.Bootstrap;
 using MxGateway.Worker.Ipc;
+using MxGateway.Worker.MxAccess;
+using MxGateway.Worker.Sta;
 
 namespace MxGateway.Worker.Tests.Ipc;
 
@@ -28,7 +33,9 @@ public sealed class WorkerPipeClientTests
             PipeTransmissionMode.Byte,
             PipeOptions.Asynchronous);
 
-        WorkerPipeClient client = new(connectTimeoutMilliseconds: 5000);
+        WorkerPipeClient client = new(
+            connectTimeoutMilliseconds: 5000,
+            (stream, options) => CreateSession(stream, options));
         Task clientTask = client.RunAsync(workerOptions);
 
         await Task.Factory.FromAsync(server.BeginWaitForConnection, server.EndWaitForConnection, null);
@@ -56,6 +63,86 @@ public sealed class WorkerPipeClientTests
         WorkerEnvelope ready = await reader.ReadAsync();
         Assert.Equal(WorkerEnvelope.BodyOneofCase.WorkerReady, ready.BodyCase);
 
+        await writer.WriteAsync(new WorkerEnvelope
+        {
+            ProtocolVersion = GatewayContractInfo.WorkerProtocolVersion,
+            SessionId = "session-1",
+            Sequence = 2,
+            WorkerShutdown = new WorkerShutdown
+            {
+                GracePeriod = Duration.FromTimeSpan(TimeSpan.FromSeconds(1)),
+                Reason = "test-complete",
+            },
+        });
+
+        WorkerEnvelope shutdownAck = await reader.ReadAsync();
+        Assert.Equal(WorkerEnvelope.BodyOneofCase.WorkerShutdownAck, shutdownAck.BodyCase);
         await clientTask;
     }
+
+    private static WorkerPipeSession CreateSession(
+        Stream stream,
+        WorkerFrameProtocolOptions options)
+    {
+        return new WorkerPipeSession(
+            new WorkerFrameReader(stream, options),
+            new WorkerFrameWriter(stream, options),
+            options,
+            () => 1234,
+            new WorkerPipeSessionOptions
+            {
+                HeartbeatInterval = TimeSpan.FromSeconds(30),
+                HeartbeatGrace = TimeSpan.FromSeconds(30),
+            },
+            () => new FakeRuntimeSession());
+    }
+
+    private sealed class FakeRuntimeSession : IWorkerRuntimeSession
+    {
+        public Task<WorkerReady> StartAsync(
+            int workerProcessId,
+            CancellationToken cancellationToken = default)
+        {
+            return Task.FromResult(new WorkerReady
+            {
+                WorkerProcessId = workerProcessId,
+                MxaccessProgid = MxGateway.Worker.MxAccess.MxAccessInteropInfo.ProgId,
+                MxaccessClsid = MxGateway.Worker.MxAccess.MxAccessInteropInfo.Clsid,
+                ReadyTimestamp = Timestamp.FromDateTimeOffset(DateTimeOffset.UtcNow),
+            });
+        }
+
+        public Task<MxCommandReply> DispatchAsync(StaCommand command)
+        {
+            return Task.FromResult(new MxCommandReply
+            {
+                SessionId = command.SessionId,
+                CorrelationId = command.CorrelationId,
+                Kind = command.Kind,
+                ProtocolStatus = new ProtocolStatus
+                {
+                    Code = ProtocolStatusCode.Ok,
+                    Message = "OK",
+                },
+            });
+        }
+
+        public WorkerRuntimeHeartbeatSnapshot CaptureHeartbeat()
+        {
+            return new WorkerRuntimeHeartbeatSnapshot(
+                DateTimeOffset.UtcNow,
+                pendingCommandCount: 0,
+                outboundEventQueueDepth: 0,
+                lastEventSequence: 0,
+                currentCommandCorrelationId: string.Empty);
+        }
+
+        public void RequestShutdown()
+        {
+        }
+
+        public void Dispose()
+        {
+        }
+    }
 }

src/MxGateway.Worker.Tests/Ipc/WorkerPipeSessionTests.cs

@@ -1,11 +1,16 @@
+using System;
 using System.Collections.Generic;
 using System.IO;
+using System.IO.Pipes;
 using System.Runtime.InteropServices;
 using System.Threading;
 using System.Threading.Tasks;
+using Google.Protobuf.WellKnownTypes;
 using MxGateway.Contracts;
 using MxGateway.Contracts.Proto;
 using MxGateway.Worker.Ipc;
+using MxGateway.Worker.MxAccess;
+using MxGateway.Worker.Sta;
 
 namespace MxGateway.Worker.Tests.Ipc;
 
@@ -147,6 +152,127 @@ public sealed class WorkerPipeSessionTests
         Assert.Equal(ProtocolStatusCode.WorkerUnavailable, written[1].WorkerFault.ProtocolStatus.Code);
     }
 
+    [Fact]
+    public async Task RunAsync_SendsHeartbeatPayloadFromRuntimeSnapshot()
+    {
+        using CancellationTokenSource cancellation = new(TimeSpan.FromSeconds(5));
+        using PipePair pipePair = await PipePair.CreateAsync(cancellation.Token);
+        FakeRuntimeSession runtime = new();
+        runtime.SetSnapshot(new WorkerRuntimeHeartbeatSnapshot(
+            DateTimeOffset.UtcNow,
+            pendingCommandCount: 2,
+            outboundEventQueueDepth: 3,
+            lastEventSequence: 42,
+            currentCommandCorrelationId: "current-command"));
+        WorkerPipeSession session = CreatePipeSession(
+            pipePair.WorkerStream,
+            runtime,
+            new WorkerPipeSessionOptions
+            {
+                HeartbeatInterval = TimeSpan.FromMilliseconds(20),
+                HeartbeatGrace = TimeSpan.FromSeconds(5),
+            });
+        Task runTask = session.RunAsync(cancellation.Token);
+
+        await CompleteGatewayHandshakeAsync(pipePair, cancellation.Token);
+        await ThrowIfCompletedAsync(runTask);
+
+        WorkerEnvelope heartbeat = await ReadUntilAsync(
+            pipePair.GatewayReader,
+            WorkerEnvelope.BodyOneofCase.WorkerHeartbeat,
+            cancellation.Token);
+
+        Assert.Equal(WorkerState.ExecutingCommand, heartbeat.WorkerHeartbeat.State);
+        Assert.Equal(1234, heartbeat.WorkerHeartbeat.WorkerProcessId);
+        Assert.Equal(2u, heartbeat.WorkerHeartbeat.PendingCommandCount);
+        Assert.Equal(3u, heartbeat.WorkerHeartbeat.OutboundEventQueueDepth);
+        Assert.Equal(42UL, heartbeat.WorkerHeartbeat.LastEventSequence);
+        Assert.Equal("current-command", heartbeat.WorkerHeartbeat.CurrentCommandCorrelationId);
+
+        await SendShutdownAndWaitAsync(pipePair, runTask, cancellation.Token);
+    }
+
+    [Fact]
+    public async Task RunAsync_WhenCommandIsExecuting_HeartbeatReportsCurrentCorrelation()
+    {
+        using CancellationTokenSource cancellation = new(TimeSpan.FromSeconds(5));
+        using PipePair pipePair = await PipePair.CreateAsync(cancellation.Token);
+        FakeRuntimeSession runtime = new()
+        {
+            BlockDispatch = true,
+        };
+        WorkerPipeSession session = CreatePipeSession(
+            pipePair.WorkerStream,
+            runtime,
+            new WorkerPipeSessionOptions
+            {
+                HeartbeatInterval = TimeSpan.FromMilliseconds(20),
+                HeartbeatGrace = TimeSpan.FromSeconds(5),
+            });
+        Task runTask = session.RunAsync(cancellation.Token);
+        await CompleteGatewayHandshakeAsync(pipePair, cancellation.Token);
+
+        await pipePair.GatewayWriter.WriteAsync(
+            CreateCommandEnvelope("command-1"),
+            cancellation.Token);
+
+        Assert.True(runtime.DispatchStarted.Wait(TimeSpan.FromSeconds(2)));
+        WorkerEnvelope heartbeat = await ReadUntilAsync(
+            pipePair.GatewayReader,
+            WorkerEnvelope.BodyOneofCase.WorkerHeartbeat,
+            envelope => envelope.WorkerHeartbeat.CurrentCommandCorrelationId == "command-1",
+            cancellation.Token);
+
+        Assert.Equal("command-1", heartbeat.WorkerHeartbeat.CurrentCommandCorrelationId);
+        Assert.Equal(WorkerState.ExecutingCommand, heartbeat.WorkerHeartbeat.State);
+
+        runtime.ReleaseDispatch();
+        WorkerEnvelope reply = await ReadUntilAsync(
+            pipePair.GatewayReader,
+            WorkerEnvelope.BodyOneofCase.WorkerCommandReply,
+            cancellation.Token);
+
+        Assert.Equal("command-1", reply.CorrelationId);
+        Assert.Equal(ProtocolStatusCode.Ok, reply.WorkerCommandReply.Reply.ProtocolStatus.Code);
+
+        await SendShutdownAndWaitAsync(pipePair, runTask, cancellation.Token);
+    }
+
+    [Fact]
+    public async Task RunAsync_WhenStaActivityIsStale_WritesWatchdogFault()
+    {
+        using CancellationTokenSource cancellation = new(TimeSpan.FromSeconds(5));
+        using PipePair pipePair = await PipePair.CreateAsync(cancellation.Token);
+        FakeRuntimeSession runtime = new();
+        runtime.SetSnapshot(new WorkerRuntimeHeartbeatSnapshot(
+            DateTimeOffset.UtcNow - TimeSpan.FromSeconds(5),
+            pendingCommandCount: 0,
+            outboundEventQueueDepth: 0,
+            lastEventSequence: 0,
+            currentCommandCorrelationId: "stuck-command"));
+        WorkerPipeSession session = CreatePipeSession(
+            pipePair.WorkerStream,
+            runtime,
+            new WorkerPipeSessionOptions
+            {
+                HeartbeatInterval = TimeSpan.FromMilliseconds(20),
+                HeartbeatGrace = TimeSpan.FromMilliseconds(50),
+            });
+        Task runTask = session.RunAsync(cancellation.Token);
+        await CompleteGatewayHandshakeAsync(pipePair, cancellation.Token);
+
+        WorkerEnvelope fault = await ReadUntilAsync(
+            pipePair.GatewayReader,
+            WorkerEnvelope.BodyOneofCase.WorkerFault,
+            cancellation.Token);
+
+        Assert.Equal(WorkerFaultCategory.StaHung, fault.WorkerFault.Category);
+        Assert.Equal("stuck-command", fault.WorkerFault.CommandMethod);
+        Assert.Contains("STA activity is stale", fault.WorkerFault.DiagnosticMessage);
+
+        await SendShutdownAndWaitAsync(pipePair, runTask, cancellation.Token);
+    }
+
     private static WorkerPipeSession CreateSession(
         Stream inbound,
         Stream outbound,
@@ -159,6 +285,21 @@ public sealed class WorkerPipeSessionTests
             () => 1234);
     }
 
+    private static WorkerPipeSession CreatePipeSession(
+        Stream stream,
+        FakeRuntimeSession runtime,
+        WorkerPipeSessionOptions sessionOptions)
+    {
+        WorkerFrameProtocolOptions options = CreateOptions();
+        return new WorkerPipeSession(
+            new WorkerFrameReader(stream, options),
+            new WorkerFrameWriter(stream, options),
+            options,
+            () => 1234,
+            sessionOptions,
+            () => runtime);
+    }
+
     private static WorkerFrameProtocolOptions CreateOptions()
     {
         return new WorkerFrameProtocolOptions(
@@ -185,6 +326,119 @@ public sealed class WorkerPipeSessionTests
         };
     }
 
+    private static WorkerEnvelope CreateCommandEnvelope(string correlationId)
+    {
+        return new WorkerEnvelope
+        {
+            ProtocolVersion = GatewayContractInfo.WorkerProtocolVersion,
+            SessionId = SessionId,
+            Sequence = 2,
+            CorrelationId = correlationId,
+            WorkerCommand = new WorkerCommand
+            {
+                Command = new MxCommand
+                {
+                    Kind = MxCommandKind.Ping,
+                    Ping = new PingCommand
+                    {
+                        Message = "ping",
+                    },
+                },
+                EnqueueTimestamp = Timestamp.FromDateTimeOffset(DateTimeOffset.UtcNow),
+            },
+        };
+    }
+
+    private static WorkerEnvelope CreateShutdownEnvelope()
+    {
+        return new WorkerEnvelope
+        {
+            ProtocolVersion = GatewayContractInfo.WorkerProtocolVersion,
+            SessionId = SessionId,
+            Sequence = 3,
+            WorkerShutdown = new WorkerShutdown
+            {
+                GracePeriod = Duration.FromTimeSpan(TimeSpan.FromSeconds(1)),
+                Reason = "test-complete",
+            },
+        };
+    }
+
+    private static async Task CompleteGatewayHandshakeAsync(
+        PipePair pipePair,
+        CancellationToken cancellationToken)
+    {
+        await pipePair.GatewayWriter
+            .WriteAsync(CreateGatewayHelloEnvelope(), cancellationToken)
+            .ConfigureAwait(false);
+
+        WorkerEnvelope hello = await pipePair.GatewayReader.ReadAsync(cancellationToken).ConfigureAwait(false);
+        WorkerEnvelope ready = await pipePair.GatewayReader.ReadAsync(cancellationToken).ConfigureAwait(false);
+
+        Assert.Equal(WorkerEnvelope.BodyOneofCase.WorkerHello, hello.BodyCase);
+        Assert.Equal(WorkerEnvelope.BodyOneofCase.WorkerReady, ready.BodyCase);
+    }
+
+    private static async Task SendShutdownAndWaitAsync(
+        PipePair pipePair,
+        Task runTask,
+        CancellationToken cancellationToken)
+    {
+        await pipePair.GatewayWriter
+            .WriteAsync(CreateShutdownEnvelope(), cancellationToken)
+            .ConfigureAwait(false);
+
+        WorkerEnvelope shutdownAck = await ReadUntilAsync(
+            pipePair.GatewayReader,
+            WorkerEnvelope.BodyOneofCase.WorkerShutdownAck,
+            cancellationToken);
+
+        Assert.Equal(ProtocolStatusCode.Ok, shutdownAck.WorkerShutdownAck.Status.Code);
+        Task completedTask = await Task
+            .WhenAny(runTask, Task.Delay(TimeSpan.FromSeconds(2), cancellationToken))
+            .ConfigureAwait(false);
+
+        Assert.Same(runTask, completedTask);
+        await runTask.ConfigureAwait(false);
+    }
+
+    private static async Task ThrowIfCompletedAsync(Task task)
+    {
+        await Task.Delay(TimeSpan.FromMilliseconds(100));
+        if (task.IsCompleted)
+        {
+            await task;
+        }
+    }
+
+    private static Task<WorkerEnvelope> ReadUntilAsync(
+        WorkerFrameReader reader,
+        WorkerEnvelope.BodyOneofCase expectedBody,
+        CancellationToken cancellationToken)
+    {
+        return ReadUntilAsync(
+            reader,
+            expectedBody,
+            _ => true,
+            cancellationToken);
+    }
+
+    private static async Task<WorkerEnvelope> ReadUntilAsync(
+        WorkerFrameReader reader,
+        WorkerEnvelope.BodyOneofCase expectedBody,
+        Func<WorkerEnvelope, bool> predicate,
+        CancellationToken cancellationToken)
+    {
+        while (true)
+        {
+            WorkerEnvelope envelope = await reader.ReadAsync(cancellationToken).ConfigureAwait(false);
+            if (envelope.BodyCase == expectedBody && predicate(envelope))
+            {
+                return envelope;
+            }
+        }
+    }
+
     private static WorkerEnvelope[] ReadWrittenFrames(
         MemoryStream stream,
         WorkerFrameProtocolOptions options)
@@ -219,4 +473,157 @@ public sealed class WorkerPipeSessionTests
         buffer[2] = (byte)(value >> 16);
         buffer[3] = (byte)(value >> 24);
     }
+
+    private sealed class FakeRuntimeSession : IWorkerRuntimeSession
+    {
+        private readonly ManualResetEventSlim releaseDispatch = new(false);
+        private readonly object gate = new();
+        private WorkerRuntimeHeartbeatSnapshot snapshot = new(
+            DateTimeOffset.UtcNow,
+            pendingCommandCount: 0,
+            outboundEventQueueDepth: 0,
+            lastEventSequence: 0,
+            currentCommandCorrelationId: string.Empty);
+
+        public ManualResetEventSlim DispatchStarted { get; } = new(false);
+
+        public bool BlockDispatch { get; set; }
+
+        public Task<WorkerReady> StartAsync(
+            int workerProcessId,
+            CancellationToken cancellationToken = default)
+        {
+            return Task.FromResult(new WorkerReady
+            {
+                WorkerProcessId = workerProcessId,
+                MxaccessProgid = MxGateway.Worker.MxAccess.MxAccessInteropInfo.ProgId,
+                MxaccessClsid = MxGateway.Worker.MxAccess.MxAccessInteropInfo.Clsid,
+                ReadyTimestamp = Timestamp.FromDateTimeOffset(DateTimeOffset.UtcNow),
+            });
+        }
+
+        public Task<MxCommandReply> DispatchAsync(StaCommand command)
+        {
+            return Task.Run(
+                () =>
+                {
+                    SetSnapshot(new WorkerRuntimeHeartbeatSnapshot(
+                        DateTimeOffset.UtcNow,
+                        pendingCommandCount: 0,
+                        outboundEventQueueDepth: 0,
+                        lastEventSequence: 0,
+                        command.CorrelationId));
+                    DispatchStarted.Set();
+
+                    if (BlockDispatch)
+                    {
+                        releaseDispatch.Wait(TimeSpan.FromSeconds(5));
+                    }
+
+                    SetSnapshot(new WorkerRuntimeHeartbeatSnapshot(
+                        DateTimeOffset.UtcNow,
+                        pendingCommandCount: 0,
+                        outboundEventQueueDepth: 0,
+                        lastEventSequence: 0,
+                        currentCommandCorrelationId: string.Empty));
+
+                    return new MxCommandReply
+                    {
+                        SessionId = command.SessionId,
+                        CorrelationId = command.CorrelationId,
+                        Kind = command.Kind,
+                        ProtocolStatus = new ProtocolStatus
+                        {
+                            Code = ProtocolStatusCode.Ok,
+                            Message = "OK",
+                        },
+                    };
+                });
+        }
+
+        public WorkerRuntimeHeartbeatSnapshot CaptureHeartbeat()
+        {
+            lock (gate)
+            {
+                return snapshot;
+            }
+        }
+
+        public void RequestShutdown()
+        {
+            releaseDispatch.Set();
+        }
+
+        public void ReleaseDispatch()
+        {
+            releaseDispatch.Set();
+        }
+
+        public void SetSnapshot(WorkerRuntimeHeartbeatSnapshot value)
+        {
+            lock (gate)
+            {
+                snapshot = value;
+            }
+        }
+
+        public void Dispose()
+        {
+            releaseDispatch.Set();
+            releaseDispatch.Dispose();
+            DispatchStarted.Dispose();
+        }
+    }
+
+    private sealed class PipePair : IDisposable
+    {
+        private readonly NamedPipeServerStream gatewayStream;
+
+        private PipePair(
+            NamedPipeServerStream gatewayStream,
+            NamedPipeClientStream workerStream)
+        {
+            this.gatewayStream = gatewayStream;
+            WorkerStream = workerStream;
+            WorkerFrameProtocolOptions options = CreateOptions();
+            GatewayReader = new WorkerFrameReader(gatewayStream, options);
+            GatewayWriter = new WorkerFrameWriter(gatewayStream, options);
+        }
+
+        public Stream WorkerStream { get; }
+
+        public WorkerFrameReader GatewayReader { get; }
+
+        public WorkerFrameWriter GatewayWriter { get; }
+
+        public static async Task<PipePair> CreateAsync(CancellationToken cancellationToken)
+        {
+            string pipeName = $"mxaccessgw-worker-session-tests-{Guid.NewGuid():N}";
+            NamedPipeServerStream gatewayStream = new(
+                pipeName,
+                PipeDirection.InOut,
+                maxNumberOfServerInstances: 1,
+                PipeTransmissionMode.Byte,
+                PipeOptions.Asynchronous);
+            NamedPipeClientStream workerStream = new(
+                ".",
+                pipeName,
+                PipeDirection.InOut,
+                PipeOptions.Asynchronous);
+
+            Task waitForConnectionTask = gatewayStream.WaitForConnectionAsync();
+            await Task
+                .Run(() => workerStream.Connect(5000), cancellationToken)
+                .ConfigureAwait(false);
+            await waitForConnectionTask.ConfigureAwait(false);
+
+            return new PipePair(gatewayStream, workerStream);
+        }
+
+        public void Dispose()
+        {
+            WorkerStream.Dispose();
+            gatewayStream.Dispose();
+        }
+    }
 }

src/MxGateway.Worker/Ipc/WorkerPipeClient.cs

@@ -1,4 +1,5 @@
 using System;
+using System.IO;
 using System.IO.Pipes;
 using System.Threading;
 using System.Threading.Tasks;
@@ -11,6 +12,7 @@ public sealed class WorkerPipeClient : IWorkerPipeClient
     public const int DefaultConnectTimeoutMilliseconds = 30000;
 
     private readonly int _connectTimeoutMilliseconds;
+    private readonly Func<Stream, WorkerFrameProtocolOptions, WorkerPipeSession> _sessionFactory;
 
     public WorkerPipeClient()
         : this(DefaultConnectTimeoutMilliseconds)
@@ -18,6 +20,15 @@ public sealed class WorkerPipeClient : IWorkerPipeClient
     }
 
     public WorkerPipeClient(int connectTimeoutMilliseconds)
+        : this(
+            connectTimeoutMilliseconds,
+            (stream, frameOptions) => new WorkerPipeSession(stream, frameOptions))
+    {
+    }
+
+    public WorkerPipeClient(
+        int connectTimeoutMilliseconds,
+        Func<Stream, WorkerFrameProtocolOptions, WorkerPipeSession> sessionFactory)
     {
         if (connectTimeoutMilliseconds <= 0)
         {
@@ -26,6 +37,7 @@ public sealed class WorkerPipeClient : IWorkerPipeClient
                 "Worker pipe connect timeout must be greater than zero.");
         }
 
+        _sessionFactory = sessionFactory ?? throw new ArgumentNullException(nameof(sessionFactory));
         _connectTimeoutMilliseconds = connectTimeoutMilliseconds;
     }
 
@@ -48,8 +60,8 @@ public sealed class WorkerPipeClient : IWorkerPipeClient
 
         await ConnectAsync(pipe, cancellationToken).ConfigureAwait(false);
 
-        WorkerPipeSession session = new(pipe, frameOptions);
-        await session.CompleteStartupHandshakeAsync(cancellationToken).ConfigureAwait(false);
+        WorkerPipeSession session = _sessionFactory(pipe, frameOptions);
+        await session.RunAsync(cancellationToken).ConfigureAwait(false);
     }
 
     private Task ConnectAsync(

src/MxGateway.Worker/Ipc/WorkerPipeSession.cs

@@ -6,6 +6,7 @@ using System.Threading.Tasks;
 using Google.Protobuf.WellKnownTypes;
 using MxGateway.Contracts.Proto;
 using MxGateway.Worker.MxAccess;
+using MxGateway.Worker.Sta;
 
 namespace MxGateway.Worker.Ipc;
 
@@ -13,10 +14,14 @@ public sealed class WorkerPipeSession
 {
     private readonly WorkerFrameProtocolOptions _options;
     private readonly Func<int> _processIdProvider;
+    private readonly Func<IWorkerRuntimeSession> _runtimeSessionFactory;
+    private readonly WorkerPipeSessionOptions _sessionOptions;
     private readonly WorkerFrameReader _reader;
     private readonly WorkerFrameWriter _writer;
-    private MxAccessStaSession? _mxAccessStaSession;
+    private IWorkerRuntimeSession? _runtimeSession;
     private long _nextSequence;
+    private WorkerState _state = WorkerState.Starting;
+    private bool _watchdogFaultSent;
 
     public WorkerPipeSession(
         Stream stream,
@@ -34,11 +39,49 @@ public sealed class WorkerPipeSession
         WorkerFrameWriter writer,
         WorkerFrameProtocolOptions options,
         Func<int> processIdProvider)
+        : this(
+            reader,
+            writer,
+            options,
+            processIdProvider,
+            new WorkerPipeSessionOptions(),
+            () => new MxAccessStaSession())
+    {
+    }
+
+    public WorkerPipeSession(
+        WorkerFrameReader reader,
+        WorkerFrameWriter writer,
+        WorkerFrameProtocolOptions options,
+        Func<int> processIdProvider,
+        WorkerPipeSessionOptions sessionOptions,
+        Func<IWorkerRuntimeSession> runtimeSessionFactory)
     {
         _reader = reader ?? throw new ArgumentNullException(nameof(reader));
         _writer = writer ?? throw new ArgumentNullException(nameof(writer));
         _options = options ?? throw new ArgumentNullException(nameof(options));
         _processIdProvider = processIdProvider ?? throw new ArgumentNullException(nameof(processIdProvider));
+        _sessionOptions = sessionOptions ?? throw new ArgumentNullException(nameof(sessionOptions));
+        _runtimeSessionFactory = runtimeSessionFactory ?? throw new ArgumentNullException(nameof(runtimeSessionFactory));
+        _sessionOptions.Validate();
+    }
+
+    public async Task RunAsync(CancellationToken cancellationToken = default)
+    {
+        _runtimeSession = _runtimeSessionFactory();
+        try
+        {
+            await CompleteStartupHandshakeAsync(
+                token => _runtimeSession.StartAsync(_processIdProvider(), token),
+                cancellationToken).ConfigureAwait(false);
+            await RunMessageLoopAsync(cancellationToken).ConfigureAwait(false);
+        }
+        finally
+        {
+            _runtimeSession?.Dispose();
+            _runtimeSession = null;
+            _state = WorkerState.Stopped;
+        }
     }
 
     public Task CompleteStartupHandshakeAsync(CancellationToken cancellationToken = default)
@@ -76,11 +119,14 @@ public sealed class WorkerPipeSession
         try
         {
             WorkerEnvelope envelope = await _reader.ReadAsync(cancellationToken).ConfigureAwait(false);
+            _state = WorkerState.Handshaking;
             ValidateGatewayHello(envelope);
 
             await WriteWorkerHelloAsync(cancellationToken).ConfigureAwait(false);
+            _state = WorkerState.InitializingSta;
             WorkerReady ready = await initializeMxAccessAsync(cancellationToken).ConfigureAwait(false);
             await WriteWorkerReadyAsync(ready, cancellationToken).ConfigureAwait(false);
+            _state = WorkerState.Ready;
         }
         catch (WorkerFrameProtocolException exception)
         {
@@ -140,6 +186,174 @@ public sealed class WorkerPipeSession
         return _writer.WriteAsync(CreateEnvelope(ready), cancellationToken);
     }
 
+    private async Task RunMessageLoopAsync(CancellationToken cancellationToken)
+    {
+        using CancellationTokenSource heartbeatCancellation = CancellationTokenSource
+            .CreateLinkedTokenSource(cancellationToken);
+        Task heartbeatTask = RunHeartbeatLoopAsync(heartbeatCancellation.Token);
+
+        try
+        {
+            while (!cancellationToken.IsCancellationRequested)
+            {
+                Task<WorkerEnvelope> readTask = _reader.ReadAsync(cancellationToken);
+                Task completedTask = await Task.WhenAny(readTask, heartbeatTask).ConfigureAwait(false);
+                if (completedTask == heartbeatTask)
+                {
+                    await heartbeatTask.ConfigureAwait(false);
+                }
+
+                WorkerEnvelope envelope = await readTask.ConfigureAwait(false);
+                bool keepReading = await DispatchGatewayEnvelopeAsync(envelope, cancellationToken).ConfigureAwait(false);
+                if (!keepReading)
+                {
+                    return;
+                }
+            }
+        }
+        finally
+        {
+            heartbeatCancellation.Cancel();
+            try
+            {
+                await heartbeatTask.ConfigureAwait(false);
+            }
+            catch (OperationCanceledException)
+            {
+            }
+        }
+    }
+
+    private async Task<bool> DispatchGatewayEnvelopeAsync(
+        WorkerEnvelope envelope,
+        CancellationToken cancellationToken)
+    {
+        switch (envelope.BodyCase)
+        {
+            case WorkerEnvelope.BodyOneofCase.WorkerCommand:
+                _ = ProcessCommandAsync(envelope, cancellationToken);
+                return true;
+            case WorkerEnvelope.BodyOneofCase.WorkerShutdown:
+                await ShutdownAsync(envelope.WorkerShutdown, cancellationToken).ConfigureAwait(false);
+                return false;
+            case WorkerEnvelope.BodyOneofCase.WorkerCancel:
+                return true;
+            default:
+                throw new WorkerFrameProtocolException(
+                    WorkerFrameProtocolErrorCode.UnexpectedEnvelopeBody,
+                    $"Worker received unexpected gateway envelope body {envelope.BodyCase}.");
+        }
+    }
+
+    private async Task ProcessCommandAsync(
+        WorkerEnvelope envelope,
+        CancellationToken cancellationToken)
+    {
+        IWorkerRuntimeSession runtimeSession = _runtimeSession
+            ?? throw new InvalidOperationException("Worker runtime session has not been initialized.");
+        WorkerCommand workerCommand = envelope.WorkerCommand;
+        MxCommand command = workerCommand.Command;
+        StaCommand staCommand = new(
+            _options.SessionId,
+            envelope.CorrelationId,
+            command,
+            workerCommand.EnqueueTimestamp,
+            cancellationToken);
+
+        try
+        {
+            MxCommandReply reply = await runtimeSession.DispatchAsync(staCommand).ConfigureAwait(false);
+            await _writer
+                .WriteAsync(
+                    CreateEnvelope(new WorkerCommandReply
+                    {
+                        Reply = reply,
+                        CompletedTimestamp = Timestamp.FromDateTime(DateTime.UtcNow),
+                    }),
+                    cancellationToken)
+                .ConfigureAwait(false);
+        }
+        catch (Exception exception) when (exception is not OperationCanceledException)
+        {
+            _state = WorkerState.Faulted;
+            await TryWriteFaultAsync(
+                CreateFault(
+                    WorkerFaultCategory.MxaccessCommandFailed,
+                    staCommand.MethodName,
+                    exception),
+                cancellationToken).ConfigureAwait(false);
+        }
+    }
+
+    private async Task ShutdownAsync(
+        WorkerShutdown shutdown,
+        CancellationToken cancellationToken)
+    {
+        _state = WorkerState.ShuttingDown;
+        _runtimeSession?.RequestShutdown();
+
+        await _writer
+            .WriteAsync(
+                CreateEnvelope(
+                    new WorkerShutdownAck
+                    {
+                        Status = new ProtocolStatus
+                        {
+                            Code = ProtocolStatusCode.Ok,
+                            Message = string.IsNullOrWhiteSpace(shutdown.Reason)
+                                ? "Worker shutdown accepted."
+                                : $"Worker shutdown accepted: {shutdown.Reason}",
+                        },
+                    }),
+                cancellationToken)
+            .ConfigureAwait(false);
+    }
+
+    private async Task RunHeartbeatLoopAsync(CancellationToken cancellationToken)
+    {
+        while (!cancellationToken.IsCancellationRequested)
+        {
+            await Task.Delay(_sessionOptions.HeartbeatInterval, cancellationToken).ConfigureAwait(false);
+            IWorkerRuntimeSession? runtimeSession = _runtimeSession;
+            if (runtimeSession is null)
+            {
+                continue;
+            }
+
+            WorkerRuntimeHeartbeatSnapshot snapshot = runtimeSession.CaptureHeartbeat();
+            await _writer
+                .WriteAsync(CreateEnvelope(CreateHeartbeat(snapshot)), cancellationToken)
+                .ConfigureAwait(false);
+
+            await ReportWatchdogFaultIfNeededAsync(snapshot, cancellationToken).ConfigureAwait(false);
+        }
+    }
+
+    private async Task ReportWatchdogFaultIfNeededAsync(
+        WorkerRuntimeHeartbeatSnapshot snapshot,
+        CancellationToken cancellationToken)
+    {
+        TimeSpan staleFor = DateTimeOffset.UtcNow - snapshot.LastStaActivityUtc;
+        if (staleFor <= _sessionOptions.HeartbeatGrace)
+        {
+            _watchdogFaultSent = false;
+            return;
+        }
+
+        if (_watchdogFaultSent)
+        {
+            return;
+        }
+
+        _watchdogFaultSent = true;
+        await TryWriteFaultAsync(
+            CreateFault(
+                WorkerFaultCategory.StaHung,
+                snapshot.CurrentCommandCorrelationId,
+                $"STA activity is stale by {staleFor}."),
+            cancellationToken).ConfigureAwait(false);
+    }
+
     private async Task TryWriteFaultAsync(
         WorkerFrameProtocolException exception,
         CancellationToken cancellationToken)
@@ -178,6 +392,25 @@ public sealed class WorkerPipeSession
         }
     }
 
+    private async Task TryWriteFaultAsync(
+        WorkerFault fault,
+        CancellationToken cancellationToken)
+    {
+        try
+        {
+            await _writer
+                .WriteAsync(CreateEnvelope(fault), cancellationToken)
+                .ConfigureAwait(false);
+        }
+        catch (Exception faultWriteException) when (
+            faultWriteException is IOException
+            || faultWriteException is ObjectDisposedException
+            || faultWriteException is WorkerFrameProtocolException)
+        {
+            // The runtime fault remains observable through worker exit or pipe closure.
+        }
+    }
+
     private WorkerEnvelope CreateEnvelope(WorkerHello hello)
     {
         return CreateBaseEnvelope(hello);
@@ -193,6 +426,21 @@ public sealed class WorkerPipeSession
         return CreateBaseEnvelope(fault);
     }
 
+    private WorkerEnvelope CreateEnvelope(WorkerCommandReply reply)
+    {
+        return CreateBaseEnvelope(reply);
+    }
+
+    private WorkerEnvelope CreateEnvelope(WorkerShutdownAck shutdownAck)
+    {
+        return CreateBaseEnvelope(shutdownAck);
+    }
+
+    private WorkerEnvelope CreateEnvelope(WorkerHeartbeat heartbeat)
+    {
+        return CreateBaseEnvelope(heartbeat);
+    }
+
     private WorkerEnvelope CreateBaseEnvelope(WorkerHello body)
     {
         WorkerEnvelope envelope = CreateBaseEnvelope();
@@ -214,6 +462,28 @@ public sealed class WorkerPipeSession
         return envelope;
     }
 
+    private WorkerEnvelope CreateBaseEnvelope(WorkerCommandReply body)
+    {
+        WorkerEnvelope envelope = CreateBaseEnvelope();
+        envelope.CorrelationId = body.Reply?.CorrelationId ?? string.Empty;
+        envelope.WorkerCommandReply = body;
+        return envelope;
+    }
+
+    private WorkerEnvelope CreateBaseEnvelope(WorkerShutdownAck body)
+    {
+        WorkerEnvelope envelope = CreateBaseEnvelope();
+        envelope.WorkerShutdownAck = body;
+        return envelope;
+    }
+
+    private WorkerEnvelope CreateBaseEnvelope(WorkerHeartbeat body)
+    {
+        WorkerEnvelope envelope = CreateBaseEnvelope();
+        envelope.WorkerHeartbeat = body;
+        return envelope;
+    }
+
     private WorkerEnvelope CreateBaseEnvelope()
     {
         return new WorkerEnvelope
@@ -231,21 +501,39 @@ public sealed class WorkerPipeSession
 
     private async Task<WorkerReady> InitializeMxAccessAsync(CancellationToken cancellationToken)
     {
-        _mxAccessStaSession = new MxAccessStaSession();
+        _runtimeSession = new MxAccessStaSession();
         try
         {
-            return await _mxAccessStaSession
+            return await _runtimeSession
                 .StartAsync(_processIdProvider(), cancellationToken)
                 .ConfigureAwait(false);
         }
         catch
         {
-            _mxAccessStaSession.Dispose();
-            _mxAccessStaSession = null;
+            _runtimeSession.Dispose();
+            _runtimeSession = null;
             throw;
         }
     }
 
+    private WorkerHeartbeat CreateHeartbeat(WorkerRuntimeHeartbeatSnapshot snapshot)
+    {
+        WorkerState state = string.IsNullOrWhiteSpace(snapshot.CurrentCommandCorrelationId)
+            ? _state
+            : WorkerState.ExecutingCommand;
+
+        return new WorkerHeartbeat
+        {
+            WorkerProcessId = _processIdProvider(),
+            State = state,
+            LastStaActivityTimestamp = Timestamp.FromDateTimeOffset(snapshot.LastStaActivityUtc),
+            PendingCommandCount = snapshot.PendingCommandCount,
+            OutboundEventQueueDepth = snapshot.OutboundEventQueueDepth,
+            LastEventSequence = snapshot.LastEventSequence,
+            CurrentCommandCorrelationId = snapshot.CurrentCommandCorrelationId,
+        };
+    }
+
     private WorkerReady CreateWorkerReady()
     {
         return new WorkerReady
@@ -295,6 +583,42 @@ public sealed class WorkerPipeSession
         return fault;
     }
 
+    private static WorkerFault CreateFault(
+        WorkerFaultCategory category,
+        string commandMethod,
+        Exception exception)
+    {
+        WorkerFault fault = CreateFault(
+            category,
+            commandMethod,
+            exception.Message);
+        fault.ExceptionType = exception.GetType().FullName ?? string.Empty;
+        fault.ProtocolStatus = new ProtocolStatus
+        {
+            Code = ProtocolStatusCode.WorkerUnavailable,
+            Message = exception.Message,
+        };
+        return fault;
+    }
+
+    private static WorkerFault CreateFault(
+        WorkerFaultCategory category,
+        string commandMethod,
+        string diagnosticMessage)
+    {
+        return new WorkerFault
+        {
+            Category = category,
+            CommandMethod = commandMethod ?? string.Empty,
+            DiagnosticMessage = diagnosticMessage,
+            ProtocolStatus = new ProtocolStatus
+            {
+                Code = ProtocolStatusCode.WorkerUnavailable,
+                Message = diagnosticMessage,
+            },
+        };
+    }
+
     private static WorkerFaultCategory MapFaultCategory(WorkerFrameProtocolErrorCode errorCode)
     {
         return errorCode switch

src/MxGateway.Worker/Ipc/WorkerPipeSessionOptions.cs

@@ -0,0 +1,36 @@
+using System;
+
+namespace MxGateway.Worker.Ipc;
+
+public sealed class WorkerPipeSessionOptions
+{
+    public static readonly TimeSpan DefaultHeartbeatInterval = TimeSpan.FromSeconds(5);
+    public static readonly TimeSpan DefaultHeartbeatGrace = TimeSpan.FromSeconds(15);
+
+    public WorkerPipeSessionOptions()
+    {
+        HeartbeatInterval = DefaultHeartbeatInterval;
+        HeartbeatGrace = DefaultHeartbeatGrace;
+    }
+
+    public TimeSpan HeartbeatInterval { get; set; }
+
+    public TimeSpan HeartbeatGrace { get; set; }
+
+    public void Validate()
+    {
+        if (HeartbeatInterval <= TimeSpan.Zero)
+        {
+            throw new ArgumentOutOfRangeException(
+                nameof(HeartbeatInterval),
+                "Worker heartbeat interval must be greater than zero.");
+        }
+
+        if (HeartbeatGrace <= TimeSpan.Zero)
+        {
+            throw new ArgumentOutOfRangeException(
+                nameof(HeartbeatGrace),
+                "Worker heartbeat grace must be greater than zero.");
+        }
+    }
+}

src/MxGateway.Worker/MxAccess/IWorkerRuntimeSession.cs

@@ -0,0 +1,20 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using MxGateway.Contracts.Proto;
+using MxGateway.Worker.Sta;
+
+namespace MxGateway.Worker.MxAccess;
+
+public interface IWorkerRuntimeSession : IDisposable
+{
+    Task<WorkerReady> StartAsync(
+        int workerProcessId,
+        CancellationToken cancellationToken = default);
+
+    Task<MxCommandReply> DispatchAsync(StaCommand command);
+
+    WorkerRuntimeHeartbeatSnapshot CaptureHeartbeat();
+
+    void RequestShutdown();
+}

src/MxGateway.Worker/MxAccess/MxAccessStaSession.cs

@@ -7,7 +7,7 @@ using MxGateway.Worker.Sta;
 
 namespace MxGateway.Worker.MxAccess;
 
-public sealed class MxAccessStaSession : IDisposable
+public sealed class MxAccessStaSession : IWorkerRuntimeSession
 {
     private readonly IMxAccessComObjectFactory factory;
     private readonly IMxAccessEventSink eventSink;
@@ -68,6 +68,30 @@ public sealed class MxAccessStaSession : IDisposable
         return commandDispatcher.DispatchAsync(command);
     }
 
+    public WorkerRuntimeHeartbeatSnapshot CaptureHeartbeat()
+    {
+        uint pendingCommandCount = 0;
+        string currentCommandCorrelationId = string.Empty;
+
+        if (commandDispatcher is not null)
+        {
+            pendingCommandCount = (uint)commandDispatcher.PendingCommandCount;
+            currentCommandCorrelationId = commandDispatcher.CurrentCommandCorrelationId;
+        }
+
+        return new WorkerRuntimeHeartbeatSnapshot(
+            staRuntime.LastActivityUtc,
+            pendingCommandCount,
+            outboundEventQueueDepth: 0,
+            lastEventSequence: 0,
+            currentCommandCorrelationId);
+    }
+
+    public void RequestShutdown()
+    {
+        commandDispatcher?.RequestShutdown();
+    }
+
     public Task<IReadOnlyList<RegisteredServerHandle>> GetRegisteredServerHandlesAsync(
         CancellationToken cancellationToken = default)
     {
@@ -101,7 +125,7 @@ public sealed class MxAccessStaSession : IDisposable
             return;
         }
 
-        commandDispatcher?.RequestShutdown();
+        RequestShutdown();
 
         if (session is not null)
         {

src/MxGateway.Worker/MxAccess/WorkerRuntimeHeartbeatSnapshot.cs

@@ -0,0 +1,30 @@
+using System;
+
+namespace MxGateway.Worker.MxAccess;
+
+public sealed class WorkerRuntimeHeartbeatSnapshot
+{
+    public WorkerRuntimeHeartbeatSnapshot(
+        DateTimeOffset lastStaActivityUtc,
+        uint pendingCommandCount,
+        uint outboundEventQueueDepth,
+        ulong lastEventSequence,
+        string currentCommandCorrelationId)
+    {
+        LastStaActivityUtc = lastStaActivityUtc;
+        PendingCommandCount = pendingCommandCount;
+        OutboundEventQueueDepth = outboundEventQueueDepth;
+        LastEventSequence = lastEventSequence;
+        CurrentCommandCorrelationId = currentCommandCorrelationId ?? string.Empty;
+    }
+
+    public DateTimeOffset LastStaActivityUtc { get; }
+
+    public uint PendingCommandCount { get; }
+
+    public uint OutboundEventQueueDepth { get; }
+
+    public ulong LastEventSequence { get; }
+
+    public string CurrentCommandCorrelationId { get; }
+}

src/MxGateway.Worker/WorkerApplication.cs

@@ -84,7 +84,7 @@ public static class WorkerApplication
 
             pipeClient.RunAsync(options).GetAwaiter().GetResult();
 
-            logger.Information("WorkerPipeHandshakeSucceeded", new Dictionary<string, object?>
+            logger.Information("WorkerPipeSessionCompleted", new Dictionary<string, object?>
             {
                 ["session_id"] = options.SessionId,
                 ["pipe_name"] = options.PipeName,