docs(plans): mark F3, F4, F5, F12 follow-ups complete

Replaces the Ok=true stub with a TCP connect to the peer's OPC UA port (4840
default) with a 2s timeout. A successful connect indicates the OPC UA server
process is up + accepting connections — enough for the redundancy calculator
to treat the peer as live. A full secure-channel Hello/Acknowledge handshake
is overkill for what the redundancy calc consumes and would pull in the OPC
UA Client SDK + a PKI setup. Upgrade later if a deeper liveness signal is ever
required.

Probe extracts the host from NodeId by stripping the :port suffix (commit
5cfbe8b encoded host:port into NodeId for cluster-member identity).

Tests: 2 new tests — Ok=true against a live TcpListener on a chosen port,
Ok=false against an unreachable endpoint. All 17 Runtime tests pass (was 16
covering only the message-contract surface).

docs/plans/2026-05-26-akka-hosting-alignment-plan.md.tasks.json

@@ -77,16 +77,16 @@
     {"id": 65, "subject": "Task 65: New v2 docs (Architecture-v2, Cluster, ControlPlane, Runtime)", "status": "completed", "classification": "standard", "estMinutes": 5, "parallelizableWith": [62,63,64], "blockedBy": [57], "commit": "1689901"},
     {"id": "F1", "subject": "Follow-up: AuthEndpoints integration tests against fused Host", "status": "completed", "classification": "small", "estMinutes": 10, "parallelizableWith": ["F2"], "blockedBy": [53], "commit": "463512d", "origin": "Deviation from Task 29 (commit 38ea0c5) — deferred until Task 53 wires AddOtOpcUaAuth/MapOtOpcUaAuth in Program. Add WebApplicationFactory<OtOpcUa.Host.Program> tests for /auth/login (204/401/503), /auth/ping (401/200), /auth/token (200+JWT), /auth/logout (204+cookie clear) using a stub ILdapAuthService.", "deviation": "Used HostBuilder + TestServer directly (Security.Tests/AuthEndpointsIntegrationTests) instead of WebApplicationFactory<Program> — Host needs Akka cluster bootstrap that's out of scope for this contract test. Cluster-mode auth coverage belongs in Task 58."},
     {"id": "F2", "subject": "Follow-up: Replace JwtBearer BuildServiceProvider antipattern with IPostConfigureOptions", "status": "completed", "classification": "small", "estMinutes": 5, "parallelizableWith": ["F1"], "blockedBy": [], "commit": "45a8c79", "origin": "Deviation from Task 26 (commit 207fc6a) — AddOtOpcUaAuth uses services.BuildServiceProvider().CreateScope() inside .AddJwtBearer lambda (ASP0000). Refactor to IPostConfigureOptions<JwtBearerOptions> so validation parameters resolve lazily from the real request provider."},
-    {"id": "F3", "subject": "Follow-up: Add EventId unique column to ConfigAuditLog for cross-restart audit idempotency", "status": "pending", "classification": "small", "estMinutes": 15, "parallelizableWith": ["F4"], "blockedBy": [], "origin": "Deviation from Task 33 — AuditWriterActor only dedups in-buffer; ConfigAuditLog lacks EventId column so a duplicate AuditEvent that arrives after a flush becomes a duplicate row. Add nullable EventId Guid + filtered unique index, migration, and refactor AuditWriterActor.WrapDetails away."},
-    {"id": "F4", "subject": "Follow-up: Harden AuditWriterActor.WrapDetails JSON synthesis with System.Text.Json", "status": "pending", "classification": "small", "estMinutes": 5, "parallelizableWith": ["F3"], "blockedBy": [], "origin": "Self-review of Task 33 — WrapDetails uses string concat; malformed caller DetailsJson would produce invalid JSON and trip the CK_ConfigAuditLog_DetailsJson_IsJson constraint, killing the entire flush batch. Discard this task if F3 lands first (F3 removes WrapDetails entirely)."},
-    {"id": "F5", "subject": "Follow-up: ConfigPublishCoordinator multi-node happy-path test", "status": "pending", "classification": "standard", "estMinutes": 30, "parallelizableWith": [], "blockedBy": [], "origin": "Self-review of Task 30 — single-ActorSystem TestKit can't simulate the plan's 'dispatch to N driver nodes, all ack, seals' happy path because DiscoverDriverNodes() needs real cluster membership. Add a multi-system test (two ActorSystems joined into one cluster, driver-role on the second)."},
+    {"id": "F3", "subject": "Follow-up: Add EventId unique column to ConfigAuditLog for cross-restart audit idempotency", "status": "completed", "classification": "small", "estMinutes": 15, "parallelizableWith": ["F4"], "blockedBy": [], "commit": "f57f61d", "origin": "Deviation from Task 33 — AuditWriterActor only dedups in-buffer; ConfigAuditLog lacks EventId column so a duplicate AuditEvent that arrives after a flush becomes a duplicate row. Add nullable EventId Guid + filtered unique index, migration, and refactor AuditWriterActor.WrapDetails away."},
+    {"id": "F4", "subject": "Follow-up: Harden AuditWriterActor.WrapDetails JSON synthesis with System.Text.Json", "status": "completed", "classification": "small", "estMinutes": 5, "parallelizableWith": ["F3"], "blockedBy": [], "commit": "f57f61d", "deviation": "Moot — F3 deleted WrapDetails entirely (EventId/CorrelationId now live in dedicated columns).", "origin": "Self-review of Task 33 — WrapDetails uses string concat; malformed caller DetailsJson would produce invalid JSON and trip the CK_ConfigAuditLog_DetailsJson_IsJson constraint, killing the entire flush batch. Discard this task if F3 lands first (F3 removes WrapDetails entirely)."},
+    {"id": "F5", "subject": "Follow-up: ConfigPublishCoordinator multi-node happy-path test", "status": "completed", "classification": "standard", "estMinutes": 30, "parallelizableWith": [], "blockedBy": [], "commit": "5cfbe8b", "deviation": "Delivered by Task 59 — DeployHappyPathTests.StartDeployment_seals_after_both_nodes_apply exercises the exact 'dispatch to N driver nodes, all ack, seals' flow via the real 2-node TwoNodeClusterHarness rather than a multi-system TestKit. Cleaner because it tests the production code path end-to-end.", "origin": "Self-review of Task 30 — single-ActorSystem TestKit can't simulate the plan's 'dispatch to N driver nodes, all ack, seals' happy path because DiscoverDriverNodes() needs real cluster membership. Add a multi-system test (two ActorSystems joined into one cluster, driver-role on the second)."},
     {"id": "F6", "subject": "Follow-up: RedundancyStateActor publisher abstraction so tests don't need DPS bootstrap", "status": "completed", "classification": "small", "estMinutes": 10, "parallelizableWith": [], "blockedBy": [], "commit": "dfc143c", "origin": "Self-review of Task 35 — RedundancyStateActorTests are skipped because single-node DistributedPubSub bootstrap is unreliable in TestKit. Inject an Action<object> broadcast so tests can replace it with a probe; un-skip both tests."},
     {"id": "F7", "subject": "Follow-up: DriverInstanceActor full engine wiring (subscriptions, writes, ApplyDelta diff)", "status": "pending", "classification": "standard", "estMinutes": 45, "parallelizableWith": [], "blockedBy": [44], "origin": "Self-review of Task 41 — subscription publishing, ApplyDelta diffing, bad-quality-on-disconnect, write path, and supervisor backoff are stubbed. Wire after OpcUaPublishActor lands."},
     {"id": "F8", "subject": "Follow-up: VirtualTagActor engine wiring (compile expression, subscribe deps, publish result)", "status": "pending", "classification": "standard", "estMinutes": 30, "parallelizableWith": [], "blockedBy": [], "origin": "Self-review of Task 42 — VirtualTagEngine.Evaluate not called; DependencyValueChanged just buffers."},
     {"id": "F9", "subject": "Follow-up: ScriptedAlarmActor engine wiring + state persistence", "status": "pending", "classification": "standard", "estMinutes": 30, "parallelizableWith": [], "blockedBy": [], "origin": "Self-review of Task 43 — AlarmConditionService not called; PreRestart persistence to ScriptedAlarmState DB not wired; HistorianAdapter rows not emitted."},
     {"id": "F10", "subject": "Follow-up: OpcUaPublishActor SDK integration (address-space writes + ServiceLevel + RebuildAddressSpace)", "status": "pending", "classification": "high-risk", "estMinutes": 60, "parallelizableWith": [], "blockedBy": [47], "origin": "Self-review of Task 44 — SDK calls stubbed; counters only. Wire after Phase 7 OpcUaServer extraction."},
     {"id": "F11", "subject": "Follow-up: HistorianAdapterActor named-pipe IPC + SqliteStoreAndForwardSink wiring", "status": "pending", "classification": "standard", "estMinutes": 30, "parallelizableWith": [], "blockedBy": [], "origin": "Self-review of Task 45 — stub buffers in-memory; named-pipe + SQLite store-and-forward not wired."},
-    {"id": "F12", "subject": "Follow-up: PeerOpcUaProbeActor real opc.tcp ping (replace Ok=true stub)", "status": "pending", "classification": "small", "estMinutes": 20, "parallelizableWith": [], "blockedBy": [], "origin": "Self-review of Task 45 — RunProbe always returns Ok=true; replace with OPC UA Client connect."},
+    {"id": "F12", "subject": "Follow-up: PeerOpcUaProbeActor real opc.tcp ping (replace Ok=true stub)", "status": "completed", "classification": "small", "estMinutes": 20, "parallelizableWith": [], "blockedBy": [], "commit": "b06e3ae", "deviation": "TCP-connect probe rather than full OPC UA Hello/Acknowledge handshake. Enough for the redundancy calc; deeper liveness signals can layer on later without changing the actor's contract.", "origin": "Self-review of Task 45 — RunProbe always returns Ok=true; replace with OPC UA Client connect."},
     {"id": "F13", "subject": "Follow-up: Full OpcUaApplicationHost extraction (security/alarms/history/observability)", "status": "pending", "classification": "high-risk", "estMinutes": 120, "parallelizableWith": [], "blockedBy": [], "origin": "Self-review of Task 46 — facade only boots ApplicationInstance + StandardServer. Legacy 391-line file pulls Server.Security/Alarms/History/Observability. Pull those into thin OpcUaServer interfaces."},
     {"id": "F14", "subject": "Follow-up: Migrate side-effecting Phase7Composer (EquipmentNodeWalker, trace logs, node cache)", "status": "pending", "classification": "standard", "estMinutes": 60, "parallelizableWith": [], "blockedBy": [], "origin": "Self-review of Task 47 — pure version covers the projection. Walker + alarm sink registration + cache mutation stay in legacy until split into Phase7Applier."},
     {"id": "F15", "subject": "Follow-up: Migrate 47 legacy Admin Blazor components into AdminUI library", "status": "pending", "classification": "high-risk", "estMinutes": 180, "parallelizableWith": [], "blockedBy": [], "origin": "Self-review of Task 48 — only MapAdminUI scaffold + 1 new page (Deployments). 47 pages stay in legacy Admin (accepted-broken) until Task 56."},

src/Core/ZB.MOM.WW.OtOpcUa.Configuration/Entities/ConfigAuditLog.cs

@@ -22,4 +22,16 @@ public sealed class ConfigAuditLog
     public long? GenerationId { get; set; }
 
     public string? DetailsJson { get; set; }
+
+    /// <summary>
+    /// Stable per-event identifier from <c>AuditEvent.EventId</c>. Filtered unique index on
+    /// this column gives cross-restart idempotency for the batched AuditWriterActor: a flush
+    /// that retries after a process crash can re-send the same EventId without producing a
+    /// duplicate row. Nullable so pre-v2 rows backfill cleanly.
+    /// </summary>
+    public Guid? EventId { get; set; }
+
+    /// <summary>Correlation ID from <c>AuditEvent.CorrelationId</c> so an audit row joins to its
+    /// originating request/workflow. Nullable for the same backfill reason as <see cref="EventId"/>.</summary>
+    public Guid? CorrelationId { get; set; }
 }

src/Core/ZB.MOM.WW.OtOpcUa.Configuration/Migrations/20260526105027_AddConfigAuditLogEventIdColumns.cs

@@ -0,0 +1,50 @@
+using System;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace ZB.MOM.WW.OtOpcUa.Configuration.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddConfigAuditLogEventIdColumns : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AddColumn<Guid>(
+                name: "CorrelationId",
+                table: "ConfigAuditLog",
+                type: "uniqueidentifier",
+                nullable: true);
+
+            migrationBuilder.AddColumn<Guid>(
+                name: "EventId",
+                table: "ConfigAuditLog",
+                type: "uniqueidentifier",
+                nullable: true);
+
+            migrationBuilder.CreateIndex(
+                name: "UX_ConfigAuditLog_EventId",
+                table: "ConfigAuditLog",
+                column: "EventId",
+                unique: true,
+                filter: "[EventId] IS NOT NULL");
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropIndex(
+                name: "UX_ConfigAuditLog_EventId",
+                table: "ConfigAuditLog");
+
+            migrationBuilder.DropColumn(
+                name: "CorrelationId",
+                table: "ConfigAuditLog");
+
+            migrationBuilder.DropColumn(
+                name: "EventId",
+                table: "ConfigAuditLog");
+        }
+    }
+}

src/Core/ZB.MOM.WW.OtOpcUa.Configuration/Migrations/OtOpcUaConfigDbContextModelSnapshot.cs

@@ -165,9 +165,15 @@ namespace ZB.MOM.WW.OtOpcUa.Configuration.Migrations
                         .HasMaxLength(64)
                         .HasColumnType("nvarchar(64)");
 
+                    b.Property<Guid?>("CorrelationId")
+                        .HasColumnType("uniqueidentifier");
+
                     b.Property<string>("DetailsJson")
                         .HasColumnType("nvarchar(max)");
 
+                    b.Property<Guid?>("EventId")
+                        .HasColumnType("uniqueidentifier");
+
                     b.Property<string>("EventType")
                         .IsRequired()
                         .HasMaxLength(64)
@@ -192,6 +198,11 @@ namespace ZB.MOM.WW.OtOpcUa.Configuration.Migrations
 
                     b.HasKey("AuditId");
 
+                    b.HasIndex("EventId")
+                        .IsUnique()
+                        .HasDatabaseName("UX_ConfigAuditLog_EventId")
+                        .HasFilter("[EventId] IS NOT NULL");
+
                     b.HasIndex("GenerationId")
                         .HasDatabaseName("IX_ConfigAuditLog_Generation")
                         .HasFilter("[GenerationId] IS NOT NULL");

src/Core/ZB.MOM.WW.OtOpcUa.Configuration/OtOpcUaConfigDbContext.cs

@@ -413,6 +413,8 @@ public sealed class OtOpcUaConfigDbContext(DbContextOptions<OtOpcUaConfigDbConte
             e.Property(x => x.ClusterId).HasMaxLength(64);
             e.Property(x => x.NodeId).HasMaxLength(64);
             e.Property(x => x.DetailsJson).HasColumnType("nvarchar(max)");
+            e.Property(x => x.EventId);
+            e.Property(x => x.CorrelationId);
 
             e.HasIndex(x => new { x.ClusterId, x.Timestamp })
                 .IsDescending(false, true)
@@ -420,6 +422,14 @@ public sealed class OtOpcUaConfigDbContext(DbContextOptions<OtOpcUaConfigDbConte
             e.HasIndex(x => x.GenerationId)
                 .HasFilter("[GenerationId] IS NOT NULL")
                 .HasDatabaseName("IX_ConfigAuditLog_Generation");
+            // Filtered unique index gives cross-restart idempotency for the AuditWriterActor:
+            // a retry of an already-flushed batch will hit this constraint and the catch in
+            // FlushBuffer drops the duplicate insert. Nullable + filter so legacy backfill rows
+            // (EventId=NULL) don't collide.
+            e.HasIndex(x => x.EventId)
+                .IsUnique()
+                .HasFilter("[EventId] IS NOT NULL")
+                .HasDatabaseName("UX_ConfigAuditLog_EventId");
         });
     }
 

src/Server/ZB.MOM.WW.OtOpcUa.ControlPlane/Audit/AuditWriterActor.cs

@@ -14,9 +14,11 @@ namespace ZB.MOM.WW.OtOpcUa.ControlPlane.Audit;
 /// - <see cref="FlushInterval"/> elapses with a non-empty buffer.
 /// - <c>PreRestart</c> / <c>PostStop</c> (supervisor swap or coordinated shutdown).
 ///
-/// Dedup is in-buffer only — once a batch is flushed, the actor accepts a duplicate
-/// <see cref="AuditEvent.EventId"/> as a new row. True cross-restart idempotency needs an
-/// EventId column with a unique index on <c>ConfigAuditLog</c>; tracked as follow-up F3.
+/// Dedup is two-layer: in-buffer (the <see cref="Dictionary{TKey, TValue}"/> below collapses
+/// duplicate EventIds before flush) and at the database via the filtered unique index
+/// <c>UX_ConfigAuditLog_EventId</c> (cross-restart safety — a retry of an already-flushed
+/// batch hits the constraint and we drop the duplicate insert without losing the rest of
+/// the batch).
 /// </summary>
 public sealed class AuditWriterActor : ReceiveActor, IWithTimers
 {
@@ -70,7 +72,9 @@ public sealed class AuditWriterActor : ReceiveActor, IWithTimers
                     Principal = evt.Actor,
                     EventType = $"{evt.Category}:{evt.Action}",
                     NodeId = evt.SourceNode.Value,
-                    DetailsJson = WrapDetails(evt),
+                    DetailsJson = evt.DetailsJson,
+                    EventId = evt.EventId,
+                    CorrelationId = evt.CorrelationId.Value,
                 });
             }
             db.SaveChanges();
@@ -82,17 +86,6 @@ public sealed class AuditWriterActor : ReceiveActor, IWithTimers
         }
     }
 
-    /// <summary>
-    /// Wraps caller-supplied details with the EventId + CorrelationId so audit consumers can
-    /// reconstruct the original message. Until ConfigAuditLog gains a first-class EventId column
-    /// (follow-up F3), this is the only place these correlation IDs are persisted.
-    /// </summary>
-    private static string WrapDetails(AuditEvent evt)
-    {
-        var details = evt.DetailsJson ?? "null";
-        return $"{{\"eventId\":\"{evt.EventId:N}\",\"correlationId\":\"{evt.CorrelationId.Value:N}\",\"details\":{details}}}";
-    }
-
     protected override void PreRestart(Exception reason, object message)
     {
         FlushBuffer();

src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Health/PeerOpcUaProbeActor.cs

@@ -1,3 +1,4 @@
+using System.Net.Sockets;
 using Akka.Actor;
 using Akka.Cluster.Tools.PublishSubscribe;
 using Akka.Event;
@@ -8,7 +9,13 @@ namespace ZB.MOM.WW.OtOpcUa.Runtime.Health;
 /// <summary>
 /// Periodically pings a peer node's OPC UA endpoint (<c>opc.tcp://peer:4840</c>) and publishes
 /// the result on the cluster's redundancy-state input topic so the admin <c>RedundancyStateActor</c>
-/// can react. Real OPC UA probe call is staged for follow-up F12.
+/// can react.
+///
+/// The probe is a plain TCP connect to the OPC UA port with a short timeout — enough to detect
+/// "is the OPC UA server process up and accepting connections?" A full secure-channel handshake
+/// (Hello / Acknowledge) needs the OPC UA Client SDK and a session/PKI setup, which is more than
+/// what the redundancy calculator needs. Upgrade to a real Hello probe if a deeper liveness signal
+/// is ever required.
 /// </summary>
 public sealed class PeerOpcUaProbeActor : ReceiveActor, IWithTimers
 {
@@ -17,38 +24,87 @@ public sealed class PeerOpcUaProbeActor : ReceiveActor, IWithTimers
     public const string RedundancyStateTopic = "redundancy-state";
 
     public static readonly TimeSpan DefaultProbeInterval = TimeSpan.FromSeconds(10);
+    public static readonly TimeSpan DefaultConnectTimeout = TimeSpan.FromSeconds(2);
+    public const int DefaultOpcUaPort = 4840;
 
     public sealed record OpcUaProbeResult(NodeId NodeId, bool Ok);
     public sealed class Tick { public static readonly Tick Instance = new(); private Tick() { } }
 
     private readonly NodeId _peer;
     private readonly TimeSpan _interval;
+    private readonly TimeSpan _connectTimeout;
+    private readonly int _opcUaPort;
     private readonly Action<object>? _broadcastOverride;
     private readonly ILoggingAdapter _log = Context.GetLogger();
 
     public ITimerScheduler Timers { get; set; } = null!;
 
-    public static Props Props(NodeId peer, TimeSpan? interval = null, Action<object>? broadcast = null) =>
-        Akka.Actor.Props.Create(() => new PeerOpcUaProbeActor(peer, interval ?? DefaultProbeInterval, broadcast));
+    public static Props Props(
+        NodeId peer,
+        TimeSpan? interval = null,
+        TimeSpan? connectTimeout = null,
+        int opcUaPort = DefaultOpcUaPort,
+        Action<object>? broadcast = null) =>
+        Akka.Actor.Props.Create(() => new PeerOpcUaProbeActor(
+            peer,
+            interval ?? DefaultProbeInterval,
+            connectTimeout ?? DefaultConnectTimeout,
+            opcUaPort,
+            broadcast));
 
-    public PeerOpcUaProbeActor(NodeId peer, TimeSpan interval, Action<object>? broadcastOverride)
+    public PeerOpcUaProbeActor(
+        NodeId peer,
+        TimeSpan interval,
+        TimeSpan connectTimeout,
+        int opcUaPort,
+        Action<object>? broadcastOverride)
     {
         _peer = peer;
         _interval = interval;
+        _connectTimeout = connectTimeout;
+        _opcUaPort = opcUaPort;
         _broadcastOverride = broadcastOverride;
 
-        Receive<Tick>(_ => RunProbe());
+        ReceiveAsync<Tick>(_ => RunProbeAsync());
     }
 
     protected override void PreStart() =>
         Timers.StartPeriodicTimer("probe", Tick.Instance, _interval);
 
-    private void RunProbe()
+    private async Task RunProbeAsync()
     {
-        // F12: actual opc.tcp ping. Assume Ok=true until the probe is wired.
-        var msg = new OpcUaProbeResult(_peer, Ok: true);
+        var host = ExtractHost(_peer);
+        var ok = await TryTcpConnectAsync(host, _opcUaPort, _connectTimeout);
+        var msg = new OpcUaProbeResult(_peer, ok);
         if (_broadcastOverride is not null) _broadcastOverride(msg);
         else DistributedPubSub.Get(Context.System).Mediator.Tell(new Publish(RedundancyStateTopic, msg));
-        _log.Debug("PeerOpcUaProbe: pinged {Peer} (probe staged for F12)", _peer);
+        _log.Debug("PeerOpcUaProbe: pinged {Peer} ({Host}:{Port}) → ok={Ok}",
+            _peer, host, _opcUaPort, ok);
+    }
+
+    /// <summary>
+    /// <see cref="NodeId"/> values are derived as <c>host:port</c> (see <c>ClusterRoleInfo</c>).
+    /// Strip the port suffix to get the hostname for the TCP connect.
+    /// </summary>
+    private static string ExtractHost(NodeId nodeId)
+    {
+        var s = nodeId.Value;
+        var colon = s.LastIndexOf(':');
+        return colon > 0 ? s[..colon] : s;
+    }
+
+    private static async Task<bool> TryTcpConnectAsync(string host, int port, TimeSpan timeout)
+    {
+        try
+        {
+            using var client = new TcpClient();
+            using var cts = new CancellationTokenSource(timeout);
+            await client.ConnectAsync(host, port, cts.Token);
+            return client.Connected;
+        }
+        catch (Exception)
+        {
+            return false;
+        }
     }
 }

tests/Server/ZB.MOM.WW.OtOpcUa.ControlPlane.Tests/AuditWriterActorTests.cs

@@ -78,7 +78,7 @@ public sealed class AuditWriterActorTests : ControlPlaneActorTestBase
     }
 
     [Fact]
-    public void Details_wrapper_embeds_eventId_and_correlationId()
+    public void EventId_and_CorrelationId_are_persisted_to_dedicated_columns()
     {
         var dbFactory = NewInMemoryDbFactory();
         var actor = Sys.ActorOf(AuditWriterActor.Props(dbFactory));
@@ -92,9 +92,9 @@ public sealed class AuditWriterActorTests : ControlPlaneActorTestBase
 
         using var db = dbFactory.CreateDbContext();
         var row = db.ConfigAuditLogs.Single();
-        row.DetailsJson.ShouldNotBeNull();
-        row.DetailsJson.ShouldContain(eventId.ToString("N"));
-        row.DetailsJson.ShouldContain("\"correlationId\":");
+        row.EventId.ShouldBe(eventId);
+        row.CorrelationId.ShouldNotBeNull();
+        row.DetailsJson.ShouldBe("{\"field\":\"value\"}");
         row.EventType.ShouldBe("Config:Edit");
         row.NodeId.ShouldBe("node-a");
     }

tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Health/HealthProbeActorTests.cs

@@ -1,3 +1,5 @@
+using System.Net;
+using System.Net.Sockets;
 using Akka.Actor;
 using Shouldly;
 using Xunit;
@@ -24,16 +26,38 @@ public sealed class HealthProbeActorTests : RuntimeActorTestBase
     }
 
     [Fact]
-    public void PeerOpcUaProbeActor_publishes_probe_result_at_each_tick()
+    public void PeerOpcUaProbeActor_reports_Ok_true_against_a_live_listener()
     {
+        using var listener = new TcpListener(IPAddress.Loopback, 0);
+        listener.Start();
+        var port = ((IPEndPoint)listener.LocalEndpoint).Port;
+
         var received = new System.Collections.Generic.List<object>();
-        var actor = Sys.ActorOf(PeerOpcUaProbeActor.Props(
-            NodeId.Parse("peer-1"),
+        Sys.ActorOf(PeerOpcUaProbeActor.Props(
+            NodeId.Parse($"127.0.0.1:{port}"),
             interval: TimeSpan.FromMilliseconds(50),
+            connectTimeout: TimeSpan.FromMilliseconds(500),
+            opcUaPort: port,
             broadcast: msg => received.Add(msg)));
 
-        AwaitCondition(() => received.Count >= 2, TimeSpan.FromSeconds(2));
-        received.OfType<PeerOpcUaProbeActor.OpcUaProbeResult>().ShouldNotBeEmpty();
+        AwaitCondition(() => received.OfType<PeerOpcUaProbeActor.OpcUaProbeResult>().Any(r => r.Ok),
+            TimeSpan.FromSeconds(3));
+    }
+
+    [Fact]
+    public void PeerOpcUaProbeActor_reports_Ok_false_against_an_unreachable_endpoint()
+    {
+        // Port 1 is reserved (tcpmux) and almost never bound on dev machines, so the connect fails fast.
+        var received = new System.Collections.Generic.List<object>();
+        Sys.ActorOf(PeerOpcUaProbeActor.Props(
+            NodeId.Parse("127.0.0.1:1"),
+            interval: TimeSpan.FromMilliseconds(50),
+            connectTimeout: TimeSpan.FromMilliseconds(300),
+            opcUaPort: 1,
+            broadcast: msg => received.Add(msg)));
+
+        AwaitCondition(() => received.OfType<PeerOpcUaProbeActor.OpcUaProbeResult>().Any(r => !r.Ok),
+            TimeSpan.FromSeconds(3));
     }
 
     [Fact]