feat(mesh-phase5): tap the 4 telemetry publish seams into the local hub (DPS intact)

Each of the four telemetry publish seams now also emits its DPS payload into the node-local ITelemetryLocalHub (Phase 5), leaving the existing DistributedPubSub publish untouched: - driver-health AkkaDriverHealthPublisher -> TelemetryItem.Health - resilience DriverResilienceStatusPublisherService -> TelemetryItem.Resilience - alerts ScriptedAlarmHostActor + DriverHostActor (native) -> TelemetryItem.Alarm - script-logs VirtualTagActor + DpsScriptLogPublisher -> TelemetryItem.Script DI services take the hub as a required ctor param; actors take an optional nullable hub threaded through their Props and the real spawn sites (DriverHostActor <- ServiceCollectionExtensions; VirtualTagActor/ScriptedAlarmHostActor <- DriverHostActor), so existing test Props constructions keep compiling and simply do not emit. The hub is a no-op until a gRPC client subscribes, so the emit is safe on every node. Claude-Session: https://claude.ai/code/session_01GASWkNEi68FSCtvr6rLoEW
2026-07-23 15:27:29 -04:00
parent 9882b1d250
commit 8e5090edf3
12 changed files with 429 additions and 25 deletions
@@ -4,6 +4,7 @@ using Microsoft.Extensions.Hosting;
 using Microsoft.Extensions.Logging;
 using ZB.MOM.WW.OtOpcUa.Commons.Messages.Drivers;
 using ZB.MOM.WW.OtOpcUa.Core.Resilience;
+using ZB.MOM.WW.OtOpcUa.Runtime.Telemetry;

 namespace ZB.MOM.WW.OtOpcUa.Host.Drivers;

@@ -23,22 +24,26 @@ public sealed class DriverResilienceStatusPublisherService : BackgroundService
    private readonly DriverResilienceStatusTracker _tracker;
    private readonly Func<ActorSystem> _actorSystemAccessor;
    private readonly ILogger<DriverResilienceStatusPublisherService> _logger;
+    private readonly ITelemetryLocalHub _hub;
    private readonly TimeSpan _interval;

    /// <summary>Initializes a new instance of <see cref="DriverResilienceStatusPublisherService"/>.</summary>
    /// <param name="tracker">The process-singleton resilience-status tracker to read each tick.</param>
    /// <param name="actorSystemAccessor">Lazy accessor for the Akka <see cref="ActorSystem"/> whose DPS mediator publishes the snapshots.</param>
    /// <param name="logger">Logger for publish diagnostics.</param>
+    /// <param name="hub">The node-local live-telemetry hub each published snapshot is also emitted into (Phase 5).</param>
    /// <param name="interval">Publish cadence; defaults to 5 s when null.</param>
    public DriverResilienceStatusPublisherService(
        DriverResilienceStatusTracker tracker,
        Func<ActorSystem> actorSystemAccessor,
        ILogger<DriverResilienceStatusPublisherService> logger,
+        ITelemetryLocalHub hub,
        TimeSpan? interval = null)
    {
        _tracker = tracker;
        _actorSystemAccessor = actorSystemAccessor;
        _logger = logger;
+        _hub = hub;
        _interval = interval ?? DefaultInterval;
    }

@@ -77,7 +82,12 @@ public sealed class DriverResilienceStatusPublisherService : BackgroundService

                var mediator = DistributedPubSub.Get(_actorSystemAccessor()).Mediator;
                foreach (var message in messages)
+                {
                    mediator.Tell(new Publish(DriverResilienceStatusChanged.TopicName, message));
+                    // Phase 5: fan the same snapshot into the node-local live-telemetry hub (no-op until a
+                    // gRPC client subscribes). The DPS publish above is unchanged — a strictly additive tap.
+                    _hub.Emit(new TelemetryItem.Resilience(message));
+                }
            }
            catch (OperationCanceledException) when (stoppingToken.IsCancellationRequested)
            {
@@ -34,6 +34,7 @@ using ZB.MOM.WW.OtOpcUa.OpcUaServer;
 using ZB.MOM.WW.OtOpcUa.Runtime.DeploymentCache;
 using ZB.MOM.WW.OtOpcUa.Runtime.Historian;
 using ZB.MOM.WW.OtOpcUa.Runtime.Scripting;
+using ZB.MOM.WW.OtOpcUa.Runtime.Telemetry;
 using ZB.MOM.WW.OtOpcUa.OpcUaServer.Security;
 using ZB.MOM.WW.OtOpcUa.Runtime;
 using ZB.MOM.WW.Auth.Abstractions.Roles;
@@ -310,7 +311,9 @@ if (hasDriver)
        ? parsedLevel
        : LogEventLevel.Information;
    builder.Services.AddSingleton<IScriptLogPublisher>(sp =>
-        new DpsScriptLogPublisher(() => sp.GetRequiredService<ActorSystem>()));
+        new DpsScriptLogPublisher(
+            () => sp.GetRequiredService<ActorSystem>(),
+            sp.GetRequiredService<ITelemetryLocalHub>()));
    builder.Services.AddSingleton(sp => new ScriptRootLogger(
        ScriptRootLoggerFactory.Build(
            sp.GetRequiredService<IScriptLogPublisher>(), scriptLogFilePath, scriptLogTopicMinLevel, Serilog.Log.Logger)));
@@ -2,6 +2,7 @@ using Akka.Actor;
 using Akka.Cluster.Tools.PublishSubscribe;
 using ZB.MOM.WW.OtOpcUa.Commons.Messages.Drivers;
 using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+using ZB.MOM.WW.OtOpcUa.Runtime.Telemetry;

 namespace ZB.MOM.WW.OtOpcUa.Runtime.Drivers;

@@ -17,10 +18,16 @@ public sealed class AkkaDriverHealthPublisher : IDriverHealthPublisher
    public const string TopicName = DriverHealthChanged.TopicName;

    private readonly ActorSystem _system;
+    private readonly ITelemetryLocalHub _hub;

    /// <summary>Initializes a new instance of <see cref="AkkaDriverHealthPublisher"/>.</summary>
    /// <param name="system">The Akka actor system used to resolve the DPS mediator.</param>
-    public AkkaDriverHealthPublisher(ActorSystem system) => _system = system;
+    /// <param name="hub">The node-local live-telemetry hub each snapshot is also emitted into (Phase 5).</param>
+    public AkkaDriverHealthPublisher(ActorSystem system, ITelemetryLocalHub hub)
+    {
+        _system = system;
+        _hub = hub;
+    }

    /// <inheritdoc />
    public void Publish(string clusterId, string driverInstanceId, DriverHealth health, int errorCount5Min)
@@ -34,5 +41,8 @@ public sealed class AkkaDriverHealthPublisher : IDriverHealthPublisher
            errorCount5Min,
            DateTime.UtcNow);
        DistributedPubSub.Get(_system).Mediator.Tell(new Publish(TopicName, msg));
+        // Phase 5: fan the same snapshot into the node-local live-telemetry hub (no-op until a gRPC
+        // client subscribes). The DPS publish above is unchanged — the hub is a strictly additive tap.
+        _hub.Emit(new TelemetryItem.Health(msg));
    }
 }
@@ -26,6 +26,7 @@ using ZB.MOM.WW.OtOpcUa.OpcUaServer;
 using ZB.MOM.WW.OtOpcUa.Runtime.DeploymentCache;
 using ZB.MOM.WW.OtOpcUa.Runtime.Redundancy;
 using ZB.MOM.WW.OtOpcUa.Runtime.ScriptedAlarms;
+using ZB.MOM.WW.OtOpcUa.Runtime.Telemetry;
 using ZB.MOM.WW.OtOpcUa.Runtime.VirtualTags;
 using CommonsNodeId = ZB.MOM.WW.OtOpcUa.Commons.Types.NodeId;

@@ -118,6 +119,11 @@ public sealed class DriverHostActor : ReceiveActor, IWithTimers
    /// </summary>
    private readonly IAlarmStateStore? _alarmStateStore;

+    /// <summary>Optional node-local live-telemetry hub (Phase 5): each Primary-gated native-alarm
+    /// <c>alerts</c> transition is also emitted here, and it is threaded into the spawned VirtualTag +
+    /// ScriptedAlarm hosts. Null (admin-only nodes / tests) skips the emit and passes null down.</summary>
+    private readonly ITelemetryLocalHub? _telemetryHub;
+
    private readonly CommonsNodeId _localNode;
    private readonly IActorRef? _ackRouter;
    private readonly IDriverFactory _driverFactory;
@@ -397,6 +403,9 @@ public sealed class DriverHostActor : ReceiveActor, IWithTimers
    /// driver-role node this is the replicated LocalDb store, so condition state persists with no
    /// ConfigDb; null skips spawning the alarm host (the ConfigDb-backed EF fallback was retired in
    /// Phase 4 Task 9). Defaults to null.</param>
+    /// <param name="telemetryHub">Per-cluster mesh Phase 5: optional node-local live-telemetry hub each
+    /// Primary-gated native-alarm transition is also emitted into, and which is threaded into the spawned
+    /// VirtualTag + ScriptedAlarm hosts. Defaults to null (admin-only nodes / tests skip the emit).</param>
    /// <returns>The Akka.NET <see cref="Akka.Actor.Props"/> used to spawn this actor.</returns>
    public static Props Props(
        IDbContextFactory<OtOpcUaConfigDbContext>? dbFactory,
@@ -420,7 +429,8 @@ public sealed class DriverHostActor : ReceiveActor, IWithTimers
        string? replicationPeerHost = null,
        bool fetchAndCacheMode = false,
        IDeploymentArtifactFetcher? artifactFetcher = null,
-        IAlarmStateStore? alarmStateStore = null) =>
+        IAlarmStateStore? alarmStateStore = null,
+        ITelemetryLocalHub? telemetryHub = null) =>
        // WARNING: this forwarding list is POSITIONAL, and Props.Create compiles it into an
        // expression tree. Six IActorRef? parameters and several interface-typed ones mean a
        // mis-ordered argument is usually type-compatible and therefore compiles clean, then binds
@@ -431,7 +441,7 @@ public sealed class DriverHostActor : ReceiveActor, IWithTimers
            healthPublisher, virtualTagEvaluator, historyWriter, virtualTagHostOverride,
            loggerFactory, scriptRootLogger, scriptedAlarmHostOverride, invokerFactory, driverMemberCountProvider,
            deploymentArtifactCache, redundancyRoleView, replicationPeerHost, fetchAndCacheMode, artifactFetcher,
-            alarmStateStore));
+            alarmStateStore, telemetryHub));

    /// <summary>Initializes a new DriverHostActor with the specified dependencies.</summary>
    /// <param name="dbFactory">Database context factory for configuration database access.</param>
@@ -469,6 +479,9 @@ public sealed class DriverHostActor : ReceiveActor, IWithTimers
    /// <param name="alarmStateStore">Per-cluster mesh Phase 4: scripted-alarm condition-state store. On a
    /// driver-role node this is the replicated LocalDb store; null skips spawning the alarm host (the
    /// ConfigDb-backed EF fallback was retired in Phase 4 Task 9).</param>
+    /// <param name="telemetryHub">Per-cluster mesh Phase 5: optional node-local live-telemetry hub each
+    /// Primary-gated native-alarm transition is also emitted into, and which is threaded into the spawned
+    /// VirtualTag + ScriptedAlarm hosts. Null (admin-only nodes / tests) skips the emit and passes null down.</param>
    public DriverHostActor(
        IDbContextFactory<OtOpcUaConfigDbContext>? dbFactory,
        CommonsNodeId localNode,
@@ -491,8 +504,10 @@ public sealed class DriverHostActor : ReceiveActor, IWithTimers
        string? replicationPeerHost = null,
        bool fetchAndCacheMode = false,
        IDeploymentArtifactFetcher? artifactFetcher = null,
-        IAlarmStateStore? alarmStateStore = null)
+        IAlarmStateStore? alarmStateStore = null,
+        ITelemetryLocalHub? telemetryHub = null)
    {
+        _telemetryHub = telemetryHub;
        _deploymentArtifactCache = deploymentArtifactCache;
        _redundancyRoleView = redundancyRoleView;
        _replicationPeerHost = replicationPeerHost;
@@ -577,7 +592,7 @@ public sealed class DriverHostActor : ReceiveActor, IWithTimers
        }

        _virtualTagHost = Context.ActorOf(
-            VirtualTagHostActor.Props(_opcUaPublishActor, _dependencyMux, _virtualTagEvaluator, _historyWriter),
+            VirtualTagHostActor.Props(_opcUaPublishActor, _dependencyMux, _virtualTagEvaluator, _historyWriter, _telemetryHub),
            "virtual-tag-host");
    }

@@ -630,7 +645,8 @@ public sealed class DriverHostActor : ReceiveActor, IWithTimers
        var engine = new ScriptedAlarmEngine(
            upstream, store, new ScriptLoggerFactory(_scriptRootLogger.Logger), _scriptRootLogger.Logger);
        _scriptedAlarmHost = Context.ActorOf(
-            ScriptedAlarmHostActor.Props(_opcUaPublishActor, _dependencyMux, upstream, engine, _localNode),
+            ScriptedAlarmHostActor.Props(
+                _opcUaPublishActor, _dependencyMux, upstream, engine, _localNode, telemetryHub: _telemetryHub),
            "scripted-alarm-host");
    }

@@ -1402,7 +1418,7 @@ public sealed class DriverHostActor : ReceiveActor, IWithTimers
            var meta = _alarmMetaByNodeId.TryGetValue(nodeId, out var m)
                ? m : (EquipmentId: nodeId, Name: nodeId, AlarmType: "AlarmCondition", HistorizeToAveva: (bool?)null,
                    ReferencingEquipmentPaths: (IReadOnlyList<string>)Array.Empty<string>());
-            _mediator.Tell(new Publish(ScriptedAlarmHostActor.AlertsTopic, new AlarmTransitionEvent(
+            var alertEvent = new AlarmTransitionEvent(
                AlarmId: nodeId,
                EquipmentPath: meta.EquipmentId,
                AlarmName: meta.Name,
@@ -1424,7 +1440,12 @@ public sealed class DriverHostActor : ReceiveActor, IWithTimers
                HistorizeToAveva: meta.HistorizeToAveva,
                // WP4: the Area/Line/Equipment UNS paths that reference this raw condition — the /alerts row
                // renders them as the equipment list (empty for a raw condition no equipment references yet).
-                ReferencingEquipmentPaths: meta.ReferencingEquipmentPaths)));
+                ReferencingEquipmentPaths: meta.ReferencingEquipmentPaths);
+            _mediator.Tell(new Publish(ScriptedAlarmHostActor.AlertsTopic, alertEvent));
+            // Phase 5: fan the same transition into the node-local live-telemetry hub (no-op until a gRPC
+            // client subscribes). The DPS publish above is unchanged — a strictly additive tap, riding the
+            // same Primary gate (only reached when serviceAlertsAsPrimary).
+            _telemetryHub?.Emit(new TelemetryItem.Alarm(alertEvent));
        }
    }

@@ -11,6 +11,7 @@ using ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms;
 using ZB.MOM.WW.OtOpcUa.OpcUaServer;
 using ZB.MOM.WW.OtOpcUa.Runtime.Drivers;
 using ZB.MOM.WW.OtOpcUa.Runtime.OpcUa;
+using ZB.MOM.WW.OtOpcUa.Runtime.Telemetry;
 using ZB.MOM.WW.OtOpcUa.Runtime.VirtualTags;

 namespace ZB.MOM.WW.OtOpcUa.Runtime.ScriptedAlarms;
@@ -116,6 +117,10 @@ public sealed class ScriptedAlarmHostActor : ReceiveActor
    /// alerts-emit gate reads while the role is unknown. Null ⇒ read the live cluster state.</summary>
    private readonly Func<int>? _driverMemberCountProvider;

+    /// <summary>Optional node-local live-telemetry hub (Phase 5): each cluster-wide <c>alerts</c> transition
+    /// is also emitted here for the gRPC streaming service. Null (tests / no hub wired) skips the emit.</summary>
+    private readonly ITelemetryLocalHub? _telemetryHub;
+
    /// <summary>Monotonic load generation, bumped on every <see cref="OnApply"/>. The continuation that
    /// pipes back an <see cref="AlarmsLoaded"/> captures the generation it was started under; a stale
    /// completion (an earlier generation arriving after a newer apply) is discarded in
@@ -138,6 +143,10 @@ public sealed class ScriptedAlarmHostActor : ReceiveActor
    /// <param name="localNode">The local cluster node id, used to read this node's <see cref="RedundancyRole"/>
    /// from the <c>redundancy-state</c> topic so only the Primary publishes the cluster-wide <c>alerts</c>
    /// transition. Null (the default) leaves the role unknown ⇒ default-emit (single-node deploys + tests).</param>
+    /// <param name="driverMemberCountProvider">Test seam (archreview 03/S4): overrides the count of Up
+    /// <c>driver</c>-role cluster members the alerts-emit gate reads while the role is unknown.</param>
+    /// <param name="telemetryHub">Optional node-local live-telemetry hub (Phase 5) each cluster-wide
+    /// <c>alerts</c> transition is also emitted into; null (tests) skips the emit.</param>
    /// <returns>The <see cref="Akka.Actor.Props"/> used to instantiate the actor.</returns>
    public static Props Props(
        IActorRef publishActor,
@@ -145,8 +154,9 @@ public sealed class ScriptedAlarmHostActor : ReceiveActor
        DependencyMuxTagUpstreamSource upstream,
        ScriptedAlarmEngine engine,
        NodeId? localNode = null,
-        Func<int>? driverMemberCountProvider = null) =>
-        Akka.Actor.Props.Create(() => new ScriptedAlarmHostActor(publishActor, mux, upstream, engine, localNode, driverMemberCountProvider));
+        Func<int>? driverMemberCountProvider = null,
+        ITelemetryLocalHub? telemetryHub = null) =>
+        Akka.Actor.Props.Create(() => new ScriptedAlarmHostActor(publishActor, mux, upstream, engine, localNode, driverMemberCountProvider, telemetryHub));

    /// <summary>Initializes a new instance of the <see cref="ScriptedAlarmHostActor"/> class.</summary>
    /// <param name="publishActor">The OPC UA publish actor emissions are bridged to.</param>
@@ -159,13 +169,16 @@ public sealed class ScriptedAlarmHostActor : ReceiveActor
    /// <param name="driverMemberCountProvider">Test seam (archreview 03/S4): overrides the count of Up
    /// <c>driver</c>-role cluster members the alerts-emit gate reads while the role is unknown. Null reads
    /// the live cluster state (0 on a non-cluster ActorRefProvider ⇒ single-node default-emit).</param>
+    /// <param name="telemetryHub">Optional node-local live-telemetry hub (Phase 5) each cluster-wide
+    /// <c>alerts</c> transition is also emitted into; null (tests) skips the emit.</param>
    public ScriptedAlarmHostActor(
        IActorRef publishActor,
        IActorRef? mux,
        DependencyMuxTagUpstreamSource upstream,
        ScriptedAlarmEngine engine,
        NodeId? localNode = null,
-        Func<int>? driverMemberCountProvider = null)
+        Func<int>? driverMemberCountProvider = null,
+        ITelemetryLocalHub? telemetryHub = null)
    {
        ArgumentNullException.ThrowIfNull(publishActor);
        ArgumentNullException.ThrowIfNull(upstream);
@@ -176,6 +189,7 @@ public sealed class ScriptedAlarmHostActor : ReceiveActor
        _engine = engine;
        _localNode = localNode;
        _driverMemberCountProvider = driverMemberCountProvider;
+        _telemetryHub = telemetryHub;

        // OnEvent fires on the engine's worker thread. NEVER touch Context / actor state here —
        // marshal onto the actor thread via the thread-safe Self.Tell. Keep the handler in a field
@@ -377,6 +391,10 @@ public sealed class ScriptedAlarmHostActor : ReceiveActor
        }

        _mediator.Tell(new Publish(AlertsTopic, evt));
+        // Phase 5: fan the same transition into the node-local live-telemetry hub (no-op until a gRPC
+        // client subscribes). The DPS publish above is unchanged — a strictly additive tap, and it rides
+        // the same Primary gate as the publish (only the Primary reaches this line).
+        _telemetryHub?.Emit(new TelemetryItem.Alarm(evt));
    }

    /// <summary>Count of Up cluster members carrying the <c>driver</c> role, for the alerts-emit gate. Uses
@@ -2,6 +2,7 @@ using Akka.Actor;
 using Akka.Cluster.Tools.PublishSubscribe;
 using ZB.MOM.WW.OtOpcUa.Commons.Messages.Logging;
 using ZB.MOM.WW.OtOpcUa.Core.Scripting;
+using ZB.MOM.WW.OtOpcUa.Runtime.Telemetry;
 using ZB.MOM.WW.OtOpcUa.Runtime.VirtualTags;

 namespace ZB.MOM.WW.OtOpcUa.Runtime.Scripting;
@@ -27,15 +28,20 @@ namespace ZB.MOM.WW.OtOpcUa.Runtime.Scripting;
 public sealed class DpsScriptLogPublisher : IScriptLogPublisher
 {
    private readonly Func<ActorSystem> _system;
+    private readonly ITelemetryLocalHub _hub;

    /// <summary>Initializes a new instance of the <see cref="DpsScriptLogPublisher"/> class.</summary>
    /// <param name="system">
    ///     Lazy accessor for the running <see cref="ActorSystem"/>. Invoked on each
    ///     <see cref="Publish"/> so registration does not depend on Akka having started yet.
    /// </param>
-    /// <exception cref="ArgumentNullException">Thrown when <paramref name="system"/> is <c>null</c>.</exception>
-    public DpsScriptLogPublisher(Func<ActorSystem> system) =>
+    /// <param name="hub">The node-local live-telemetry hub each script-log entry is also emitted into (Phase 5).</param>
+    /// <exception cref="ArgumentNullException">Thrown when <paramref name="system"/> or <paramref name="hub"/> is <c>null</c>.</exception>
+    public DpsScriptLogPublisher(Func<ActorSystem> system, ITelemetryLocalHub hub)
+    {
        _system = system ?? throw new ArgumentNullException(nameof(system));
+        _hub = hub ?? throw new ArgumentNullException(nameof(hub));
+    }

    /// <inheritdoc />
    public void Publish(ScriptLogEntry entry)
@@ -44,6 +50,9 @@ public sealed class DpsScriptLogPublisher : IScriptLogPublisher
        {
            var mediator = DistributedPubSub.Get(_system()).Mediator;
            mediator.Tell(new Publish(VirtualTagActor.ScriptLogsTopic, entry));
+            // Phase 5: fan the same entry into the node-local live-telemetry hub (no-op until a gRPC
+            // client subscribes). The DPS publish above is unchanged — the hub is a strictly additive tap.
+            _hub.Emit(new TelemetryItem.Script(entry));
        }
        catch (Exception ex)
        {
@@ -495,7 +495,11 @@ public static class ServiceCollectionExtensions
                    replicationPeerHost: replicationPeerHost,
                    fetchAndCacheMode: fetchAndCacheMode,
                    artifactFetcher: artifactFetcher,
-                    alarmStateStore: alarmStateStore),
+                    alarmStateStore: alarmStateStore,
+                    // Phase 5: the node-local live-telemetry hub (registered in AddOtOpcUaRuntime). The host
+                    // emits its Primary-gated native-alarm transitions into it and threads it into the
+                    // VirtualTag + ScriptedAlarm hosts it spawns.
+                    telemetryHub: resolver.GetService<ITelemetryLocalHub>()),
                DriverHostActorName);
            registry.Register<DriverHostActorKey>(driverHost);

@@ -6,6 +6,7 @@ using ZB.MOM.WW.OtOpcUa.Commons.Messages.Logging;
 using ZB.MOM.WW.OtOpcUa.Commons.Observability;
 using ZB.MOM.WW.OtOpcUa.Commons.OpcUa;
 using ZB.MOM.WW.OtOpcUa.Commons.Types;
+using ZB.MOM.WW.OtOpcUa.Runtime.Telemetry;

 namespace ZB.MOM.WW.OtOpcUa.Runtime.VirtualTags;

@@ -61,6 +62,7 @@ public sealed class VirtualTagActor : ReceiveActor
    private readonly Func<DPSPublisher>? _publisherFactory;
    private readonly IReadOnlyList<string> _dependencyRefs;
    private readonly IActorRef? _mux;
+    private readonly ITelemetryLocalHub? _telemetryHub;
    private readonly ILoggingAdapter _log = Context.GetLogger();
    private readonly Dictionary<string, object?> _dependencies = new(StringComparer.Ordinal);

@@ -78,6 +80,8 @@ public sealed class VirtualTagActor : ReceiveActor
    /// <param name="publisherFactory">Optional factory for creating DPS publishers.</param>
    /// <param name="dependencyRefs">Optional list of dependency tag references; defaults to empty.</param>
    /// <param name="mux">Optional reference to a dependency multiplexer actor.</param>
+    /// <param name="telemetryHub">Optional node-local live-telemetry hub each script-log entry is also
+    /// emitted into (Phase 5); null (tests) simply skips the emit.</param>
    /// <returns>A configured <see cref="Akka.Actor.Props"/> for creating the actor.</returns>
    public static Props Props(
        string virtualTagId,
@@ -86,14 +90,16 @@ public sealed class VirtualTagActor : ReceiveActor
        string? scriptId = null,
        Func<DPSPublisher>? publisherFactory = null,
        IReadOnlyList<string>? dependencyRefs = null,
-        IActorRef? mux = null) =>
+        IActorRef? mux = null,
+        ITelemetryLocalHub? telemetryHub = null) =>
        Akka.Actor.Props.Create(() => new VirtualTagActor(
            virtualTagId, expression,
            evaluator ?? NullVirtualTagEvaluator.Instance,
            scriptId ?? virtualTagId,
            publisherFactory,
            dependencyRefs ?? Array.Empty<string>(),
-            mux));
+            mux,
+            telemetryHub));

    /// <summary>Initializes a virtual tag actor with the given configuration and dependencies.</summary>
    /// <param name="virtualTagId">Unique identifier for the virtual tag.</param>
@@ -103,6 +109,8 @@ public sealed class VirtualTagActor : ReceiveActor
    /// <param name="publisherFactory">Optional factory for creating DPS publishers.</param>
    /// <param name="dependencyRefs">List of dependency tag references that this tag depends on.</param>
    /// <param name="mux">Optional reference to a dependency multiplexer actor.</param>
+    /// <param name="telemetryHub">Optional node-local live-telemetry hub each script-log entry is also
+    /// emitted into (Phase 5); null (tests) simply skips the emit.</param>
    public VirtualTagActor(
        string virtualTagId,
        string expression,
@@ -110,7 +118,8 @@ public sealed class VirtualTagActor : ReceiveActor
        string scriptId,
        Func<DPSPublisher>? publisherFactory,
        IReadOnlyList<string> dependencyRefs,
-        IActorRef? mux)
+        IActorRef? mux,
+        ITelemetryLocalHub? telemetryHub = null)
    {
        _virtualTagId = virtualTagId;
        _scriptId = scriptId;
@@ -119,6 +128,7 @@ public sealed class VirtualTagActor : ReceiveActor
        _publisherFactory = publisherFactory;
        _dependencyRefs = dependencyRefs;
        _mux = mux;
+        _telemetryHub = telemetryHub;

        Receive<DependencyValueChanged>(OnDependencyChanged);
        Receive<ReassertValue>(_ => OnReassertValue());
@@ -259,6 +269,9 @@ public sealed class VirtualTagActor : ReceiveActor
        }

        DistributedPubSub.Get(Context.System).Mediator.Tell(new Publish(ScriptLogsTopic, entry));
+        // Phase 5: fan the same entry into the node-local live-telemetry hub (no-op until a gRPC client
+        // subscribes). The DPS publish above is unchanged — a strictly additive tap.
+        _telemetryHub?.Emit(new TelemetryItem.Script(entry));
    }
 }

@@ -6,6 +6,7 @@ using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
 using ZB.MOM.WW.OtOpcUa.Core.VirtualTags;
 using ZB.MOM.WW.OtOpcUa.OpcUaServer;
 using ZB.MOM.WW.OtOpcUa.Runtime.OpcUa;
+using ZB.MOM.WW.OtOpcUa.Runtime.Telemetry;

 namespace ZB.MOM.WW.OtOpcUa.Runtime.VirtualTags;

@@ -39,6 +40,7 @@ public sealed class VirtualTagHostActor : ReceiveActor
    // Sink for historized VirtualTag results (plans with Historize=true). NullHistoryWriter when no
    // durable historian is wired, so OnResult always has a non-null target.
    private readonly IHistoryWriter _history;
+    private readonly ITelemetryLocalHub? _telemetryHub;
    private readonly ILoggingAdapter _log = Context.GetLogger();

    // vtagId -> spawned child VirtualTagActor.
@@ -59,18 +61,22 @@ public sealed class VirtualTagHostActor : ReceiveActor
    /// <param name="historyWriter">Sink for results whose plan has <c>Historize=true</c>. Null ⇒
    /// <see cref="NullHistoryWriter.Instance"/> (no durable historian wired), so existing call sites
    /// compile unchanged and never historize.</param>
+    /// <param name="telemetryHub">Optional node-local live-telemetry hub passed to each spawned child so
+    /// its script-log entries also emit to the Phase-5 hub; null (tests) skips the emit.</param>
    /// <returns>The <see cref="Props"/> used to spawn a <see cref="VirtualTagHostActor"/>.</returns>
    public static Props Props(IActorRef publishActor, IActorRef? mux, IVirtualTagEvaluator evaluator,
-        IHistoryWriter? historyWriter = null) =>
-        Akka.Actor.Props.Create(() => new VirtualTagHostActor(publishActor, mux, evaluator, historyWriter));
+        IHistoryWriter? historyWriter = null, ITelemetryLocalHub? telemetryHub = null) =>
+        Akka.Actor.Props.Create(() => new VirtualTagHostActor(publishActor, mux, evaluator, historyWriter, telemetryHub));

    /// <summary>Initializes a new instance of the <see cref="VirtualTagHostActor"/> class.</summary>
    /// <param name="publishActor">The OPC UA publish actor results are bridged to.</param>
    /// <param name="mux">Optional dependency multiplexer passed to each spawned child.</param>
    /// <param name="evaluator">The evaluator each child uses to compute its expression.</param>
    /// <param name="historyWriter">Sink for historized results; null ⇒ <see cref="NullHistoryWriter.Instance"/>.</param>
+    /// <param name="telemetryHub">Optional node-local live-telemetry hub passed to each spawned child so
+    /// its script-log entries also emit to the Phase-5 hub; null (tests) skips the emit.</param>
    public VirtualTagHostActor(IActorRef publishActor, IActorRef? mux, IVirtualTagEvaluator evaluator,
-        IHistoryWriter? historyWriter = null)
+        IHistoryWriter? historyWriter = null, ITelemetryLocalHub? telemetryHub = null)
    {
        ArgumentNullException.ThrowIfNull(publishActor);
        ArgumentNullException.ThrowIfNull(evaluator);
@@ -78,6 +84,7 @@ public sealed class VirtualTagHostActor : ReceiveActor
        _mux = mux;
        _evaluator = evaluator;
        _history = historyWriter ?? NullHistoryWriter.Instance;
+        _telemetryHub = telemetryHub;

        Receive<ApplyVirtualTags>(OnApply);
        Receive<VirtualTagActor.EvaluationResult>(OnResult);
@@ -166,7 +173,8 @@ public sealed class VirtualTagHostActor : ReceiveActor
                scriptId: p.VirtualTagId,
                publisherFactory: null,
                dependencyRefs: p.DependencyRefs,
-                mux: _mux));
+                mux: _mux,
+                telemetryHub: _telemetryHub));
            Context.Watch(child);
            _children[p.VirtualTagId] = child;
            newlySpawned.Add(p.VirtualTagId);
@@ -1,7 +1,12 @@
+using Akka.Actor;
+using Akka.Cluster;
+using Akka.Configuration;
+using Microsoft.Extensions.Logging.Abstractions;
 using Shouldly;
 using Xunit;
 using ZB.MOM.WW.OtOpcUa.Core.Resilience;
 using ZB.MOM.WW.OtOpcUa.Host.Drivers;
+using ZB.MOM.WW.OtOpcUa.Runtime.Telemetry;

 namespace ZB.MOM.WW.OtOpcUa.Host.IntegrationTests;

@@ -53,4 +58,81 @@ public sealed class DriverResilienceStatusPublisherServiceTests
        healthy.CurrentInFlight.ShouldBe(1);
        healthy.PublishedUtc.ShouldBe(Published);
    }
+
+    /// <summary>Per-cluster mesh Phase 5 — each snapshot the publish tick sends to the
+    /// <c>driver-resilience-status</c> DPS topic is also emitted into the node-local
+    /// <see cref="ITelemetryLocalHub"/> as a <see cref="TelemetryItem.Resilience"/>. Runs the background
+    /// service against a single-node cluster (so DistributedPubSub resolves) for a few ticks and asserts the
+    /// hub captured the tracked pair.</summary>
+    [Fact]
+    public async Task ExecuteAsync_emits_Resilience_item_per_published_snapshot()
+    {
+        // Plain self-joined single-node cluster (mirrors SecretsReplicationRegistrationTests — the
+        // xunit.v3 project cannot use Akka.TestKit.Xunit2). public-hostname is load-bearing for the bind.
+        var hocon = ConfigurationFactory.ParseString("""
+            akka {
+              loglevel = WARNING
+              actor.provider = cluster
+              remote.dot-netty.tcp {
+                hostname = "127.0.0.1"
+                public-hostname = "127.0.0.1"
+                port = 0
+              }
+              cluster { roles = ["driver"] }
+            }
+            """);
+        var sys = ActorSystem.Create("resil-hub-test", hocon);
+        try
+        {
+            var cluster = Akka.Cluster.Cluster.Get(sys);
+            cluster.Join(cluster.SelfAddress);
+            var upDeadline = DateTime.UtcNow.AddSeconds(10);
+            while (!cluster.State.Members.Any(m => m.Status == MemberStatus.Up) && DateTime.UtcNow < upDeadline)
+                await Task.Delay(50, TestContext.Current.CancellationToken);
+            cluster.State.Members.ShouldContain(m => m.Status == MemberStatus.Up);
+
+            var tracker = new DriverResilienceStatusTracker();
+            tracker.RecordCallStart("drv-1", "host-a");
+
+            var hub = new CapturingHub();
+            var service = new DriverResilienceStatusPublisherService(
+                tracker, () => sys, NullLogger<DriverResilienceStatusPublisherService>.Instance, hub,
+                interval: TimeSpan.FromMilliseconds(50));
+
+            await service.StartAsync(TestContext.Current.CancellationToken);
+            try
+            {
+                var deadline = DateTime.UtcNow.AddSeconds(5);
+                while (hub.Items.Count == 0 && DateTime.UtcNow < deadline)
+                    await Task.Delay(50, TestContext.Current.CancellationToken);
+            }
+            finally
+            {
+                await service.StopAsync(TestContext.Current.CancellationToken);
+            }
+
+            hub.Items.ShouldNotBeEmpty();
+            var item = hub.Items[0].ShouldBeOfType<TelemetryItem.Resilience>();
+            item.E.DriverInstanceId.ShouldBe("drv-1");
+            item.E.HostName.ShouldBe("host-a");
+            item.E.CurrentInFlight.ShouldBe(1);
+        }
+        finally
+        {
+            await sys.Terminate();
+        }
+    }
+
+    /// <summary>Fake hub recording every emit; <see cref="Subscribe"/> is unused here.</summary>
+    private sealed class CapturingHub : ITelemetryLocalHub
+    {
+        public List<TelemetryItem> Items { get; } = new();
+
+        public void Emit(TelemetryItem item)
+        {
+            lock (Items) Items.Add(item);
+        }
+
+        public ITelemetrySubscription Subscribe(int boundedCapacity) => throw new NotSupportedException();
+    }
 }
@@ -4,6 +4,7 @@ using Shouldly;
 using Xunit;
 using ZB.MOM.WW.OtOpcUa.Commons.Messages.Logging;
 using ZB.MOM.WW.OtOpcUa.Runtime.Scripting;
+using ZB.MOM.WW.OtOpcUa.Runtime.Telemetry;
 using ZB.MOM.WW.OtOpcUa.Runtime.Tests.Harness;
 using ZB.MOM.WW.OtOpcUa.Runtime.VirtualTags;

@@ -40,7 +41,7 @@ public sealed class DpsScriptLogPublisherTests : RuntimeActorTestBase
        probe.Send(mediator, new Subscribe(VirtualTagActor.ScriptLogsTopic, probe.Ref));
        probe.ExpectMsg<SubscribeAck>(TimeSpan.FromSeconds(10));

-        var publisher = new DpsScriptLogPublisher(() => Sys);
+        var publisher = new DpsScriptLogPublisher(() => Sys, new NoopHub());
        var entry = SampleEntry();

        // The SubscribeAck confirms the subscribe was registered, but DPS topic membership is
@@ -61,7 +62,7 @@ public sealed class DpsScriptLogPublisherTests : RuntimeActorTestBase
    public void Publish_does_not_throw_when_the_system_accessor_throws()
    {
        var publisher = new DpsScriptLogPublisher(
-            () => throw new InvalidOperationException("system not ready"));
+            () => throw new InvalidOperationException("system not ready"), new NoopHub());

        Should.NotThrow(() => publisher.Publish(SampleEntry()));
    }
@@ -70,6 +71,15 @@ public sealed class DpsScriptLogPublisherTests : RuntimeActorTestBase
    [Fact]
    public void Null_system_accessor_throws_ArgumentNullException()
    {
-        Should.Throw<ArgumentNullException>(() => new DpsScriptLogPublisher(null!));
+        Should.Throw<ArgumentNullException>(() => new DpsScriptLogPublisher(null!, new NoopHub()));
+    }
+
+    /// <summary>No-op telemetry hub for the publisher tests (the hub tap is asserted in
+    /// <c>PublishSeamEmitsToHubTests</c>; here it must simply not interfere).</summary>
+    private sealed class NoopHub : ITelemetryLocalHub
+    {
+        public void Emit(TelemetryItem item) { }
+
+        public ITelemetrySubscription Subscribe(int boundedCapacity) => throw new NotSupportedException();
    }
 }
@@ -0,0 +1,216 @@
+using System.Text.Json;
+using Akka.Actor;
+using Microsoft.EntityFrameworkCore;
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Commons.Engines;
+using ZB.MOM.WW.OtOpcUa.Commons.Messages.Alerts;
+using ZB.MOM.WW.OtOpcUa.Commons.Messages.Deploy;
+using ZB.MOM.WW.OtOpcUa.Commons.Messages.Logging;
+using ZB.MOM.WW.OtOpcUa.Commons.Types;
+using ZB.MOM.WW.OtOpcUa.Configuration;
+using ZB.MOM.WW.OtOpcUa.Configuration.Entities;
+using ZB.MOM.WW.OtOpcUa.Configuration.Enums;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+using ZB.MOM.WW.OtOpcUa.Runtime.Drivers;
+using ZB.MOM.WW.OtOpcUa.Runtime.OpcUa;
+using ZB.MOM.WW.OtOpcUa.Runtime.Scripting;
+using ZB.MOM.WW.OtOpcUa.Runtime.Telemetry;
+using ZB.MOM.WW.OtOpcUa.Runtime.Tests.Harness;
+
+namespace ZB.MOM.WW.OtOpcUa.Runtime.Tests.Telemetry;
+
+/// <summary>
+///     Per-cluster mesh Phase 5 — the four telemetry publish seams each additionally fan their DPS payload
+///     into the node-local <see cref="ITelemetryLocalHub"/>. Each test drives a producer with a capturing
+///     fake hub and asserts exactly one <see cref="TelemetryItem"/> of the correct subtype carrying the
+///     SAME payload that goes onto the DistributedPubSub topic. The DPS publish itself is unchanged and is
+///     covered by the existing per-producer tests — these only assert the additive tap.
+/// </summary>
+public sealed class PublishSeamEmitsToHubTests : RuntimeActorTestBase
+{
+    private static readonly NodeId TestNode = NodeId.Parse("telemetry-seam-test");
+    private static readonly RevisionHash RevA = RevisionHash.Parse(new string('a', 64));
+    private static readonly DateTime Ts = new(2026, 7, 23, 10, 0, 0, DateTimeKind.Utc);
+    private const string AlarmRawPath = "Plant/Modbus/dev1/temp_hi";
+
+    // --- driver-health seam (AkkaDriverHealthPublisher) → TelemetryItem.Health --------------------------
+
+    /// <summary>The driver-health publisher fans the SAME <see cref="DriverHealthChanged"/> it publishes to
+    /// the <c>driver-health</c> DPS topic into the hub as a <see cref="TelemetryItem.Health"/>.</summary>
+    [Fact]
+    public void Driver_health_publish_emits_one_Health_item_with_same_payload()
+    {
+        var hub = new CapturingHub();
+        var publisher = new AkkaDriverHealthPublisher(Sys, hub);
+
+        var health = new DriverHealth(DriverState.Degraded, Ts, "some error");
+        publisher.Publish("c1", "drv-1", health, errorCount5Min: 4);
+
+        hub.Items.Count.ShouldBe(1);
+        var item = hub.Items[0].ShouldBeOfType<TelemetryItem.Health>();
+        item.E.ClusterId.ShouldBe("c1");
+        item.E.DriverInstanceId.ShouldBe("drv-1");
+        item.E.State.ShouldBe(DriverState.Degraded.ToString());
+        item.E.LastError.ShouldBe("some error");
+        item.E.ErrorCount5Min.ShouldBe(4);
+    }
+
+    // --- script-logs seam (DpsScriptLogPublisher) → TelemetryItem.Script -------------------------------
+
+    /// <summary>The DPS script-log publisher fans the SAME <see cref="ScriptLogEntry"/> instance it publishes
+    /// to the <c>script-logs</c> topic into the hub as a <see cref="TelemetryItem.Script"/>.</summary>
+    [Fact]
+    public void Script_log_publish_emits_one_Script_item_with_same_payload()
+    {
+        var hub = new CapturingHub();
+        var publisher = new DpsScriptLogPublisher(() => Sys, hub);
+
+        var entry = new ScriptLogEntry(
+            ScriptId: "S1",
+            Level: "Information",
+            Message: "hello",
+            TimestampUtc: Ts,
+            VirtualTagId: "V1",
+            AlarmId: null,
+            EquipmentId: "EQ1");
+
+        publisher.Publish(entry);
+
+        hub.Items.Count.ShouldBe(1);
+        var item = hub.Items[0].ShouldBeOfType<TelemetryItem.Script>();
+        item.E.ShouldBeSameAs(entry); // the exact instance published to DPS
+    }
+
+    /// <summary>A null hub is rejected at construction (fail-fast, DI provides a real hub on driver nodes).</summary>
+    [Fact]
+    public void Script_log_publisher_rejects_null_hub()
+    {
+        Should.Throw<ArgumentNullException>(() => new DpsScriptLogPublisher(() => Sys, null!));
+    }
+
+    // --- alerts seam (DriverHostActor native alarm) → TelemetryItem.Alarm ------------------------------
+
+    /// <summary>A Primary-gated native-alarm transition fans the SAME <see cref="AlarmTransitionEvent"/> it
+    /// publishes to the <c>alerts</c> topic into the hub as a <see cref="TelemetryItem.Alarm"/>. Proves the
+    /// hub was threaded through <see cref="DriverHostActor"/>'s Props into the emit seam.</summary>
+    [Fact]
+    public void Native_alarm_publish_emits_one_Alarm_item_with_matching_payload()
+    {
+        var db = NewInMemoryDbFactory();
+        var deploymentId = SeedV3AlarmDeployment(db, RevA);
+
+        var hub = new CapturingHub();
+        var (actor, publish) = SpawnHostAndApply(db, deploymentId, hub);
+
+        actor.Tell(new DriverInstanceActor.AttributeAlarmPublished("drv-1", new AlarmEventArgs(
+            new StubAlarmHandle(),
+            SourceNodeId: "Temp",
+            ConditionId: AlarmRawPath,
+            AlarmType: "OffNormalAlarm",
+            Message: "temperature high",
+            Severity: AlarmSeverity.High,
+            SourceTimestampUtc: Ts,
+            Kind: AlarmTransitionKind.Raise)));
+
+        // The OPC UA condition update confirms the transition was processed (ordered before the alerts fan-out).
+        publish.ExpectMsg<OpcUaPublishActor.AlarmStateUpdate>(TimeSpan.FromSeconds(5));
+
+        // Exactly one Alarm item, carrying the same transition the alerts topic received.
+        AwaitAssert(() => hub.Items.Count.ShouldBe(1), TimeSpan.FromSeconds(5), TimeSpan.FromMilliseconds(100));
+        var item = hub.Items[0].ShouldBeOfType<TelemetryItem.Alarm>();
+        item.E.AlarmId.ShouldBe(AlarmRawPath);
+        item.E.AlarmName.ShouldBe("temp_hi");
+        item.E.TransitionKind.ShouldBe("Activated");
+        item.E.Message.ShouldBe("temperature high");
+    }
+
+    /// <summary>Spawns the host wired with the capturing hub, dispatches the deployment, and waits for the
+    /// Applied ack + the RebuildAddressSpace so the alarm map is built before the test raises an alarm.</summary>
+    private (IActorRef Actor, Akka.TestKit.TestProbe Publish) SpawnHostAndApply(
+        IDbContextFactory<OtOpcUaConfigDbContext> db, DeploymentId deploymentId, ITelemetryLocalHub hub)
+    {
+        var coordinator = CreateTestProbe();
+        var publish = CreateTestProbe();
+        var mux = CreateTestProbe();
+        var vtHost = CreateTestProbe();
+
+        var actor = Sys.ActorOf(DriverHostActor.Props(
+            db, TestNode, coordinator.Ref,
+            localRoles: new HashSet<string> { "driver" },
+            dependencyMux: mux.Ref,
+            opcUaPublishActor: publish.Ref,
+            virtualTagEvaluator: NullVirtualTagEvaluator.Instance,
+            virtualTagHostOverride: vtHost.Ref,
+            telemetryHub: hub));
+
+        actor.Tell(new DispatchDeployment(deploymentId, RevA, CorrelationId.NewId()));
+        coordinator.ExpectMsg<ApplyAck>(TimeSpan.FromSeconds(5)).Outcome.ShouldBe(ApplyAckOutcome.Applied);
+        publish.ExpectMsg<OpcUaPublishActor.RebuildAddressSpace>(TimeSpan.FromSeconds(5));
+
+        return (actor, publish);
+    }
+
+    /// <summary>Seeds a Sealed v3 deployment with a single Boolean raw tag carrying an <c>alarm</c> object so
+    /// the composer projects it as a Part 9 condition at its RawPath (mirrors DriverHostActorNativeAlarmTests).</summary>
+    private static DeploymentId SeedV3AlarmDeployment(IDbContextFactory<OtOpcUaConfigDbContext> db, RevisionHash rev)
+    {
+        var artifact = JsonSerializer.SerializeToUtf8Bytes(new
+        {
+            RawFolders = new[] { new { RawFolderId = "rf-plant", ParentRawFolderId = (string?)null, Name = "Plant", ClusterId = "c1" } },
+            DriverInstances = new[]
+            {
+                new { DriverInstanceId = "drv-1", RawFolderId = "rf-plant", Name = "Modbus", DriverType = "Modbus", DriverConfig = "{}", ClusterId = "c1", Enabled = false },
+            },
+            Devices = new[]
+            {
+                new { DeviceId = "drv-1:dev1", DriverInstanceId = "drv-1", Name = "dev1", DeviceConfig = "{}" },
+            },
+            TagGroups = Array.Empty<object>(),
+            Tags = new[]
+            {
+                new
+                {
+                    TagId = "tag-0",
+                    DeviceId = "drv-1:dev1",
+                    TagGroupId = (string?)null,
+                    Name = "temp_hi",
+                    DataType = "Boolean",
+                    AccessLevel = 0,
+                    TagConfig = JsonSerializer.Serialize(new { alarm = new { alarmType = "OffNormalAlarm", severity = 700 } }),
+                },
+            },
+        });
+
+        var id = DeploymentId.NewId();
+        using var ctx = db.CreateDbContext();
+        ctx.Deployments.Add(new Deployment
+        {
+            DeploymentId = id.Value,
+            RevisionHash = rev.Value,
+            Status = DeploymentStatus.Sealed,
+            CreatedBy = "test",
+            SealedAtUtc = DateTime.UtcNow,
+            ArtifactBlob = artifact,
+        });
+        ctx.SaveChanges();
+        return id;
+    }
+
+    /// <summary>Minimal alarm-subscription handle for building <see cref="AlarmEventArgs"/>.</summary>
+    private sealed class StubAlarmHandle : IAlarmSubscriptionHandle
+    {
+        public string DiagnosticId => "stub-alarm-sub";
+    }
+
+    /// <summary>Fake hub that records every <see cref="ITelemetryLocalHub.Emit"/>. <see cref="Subscribe"/> is
+    /// unused by the producer seams under test.</summary>
+    private sealed class CapturingHub : ITelemetryLocalHub
+    {
+        public List<TelemetryItem> Items { get; } = new();
+
+        public void Emit(TelemetryItem item) => Items.Add(item);
+
+        public ITelemetrySubscription Subscribe(int boundedCapacity) => throw new NotSupportedException();
+    }
+}