feat(phase7): route OPC UA Part 9 Acknowledge/Confirm methods to ScriptedAlarmEngine (task #24)

Gap 1 of phase-7-status.md. Intercepts AcknowledgeableConditionType_Acknowledge and
AcknowledgeableConditionType_Confirm calls in DriverNodeManager.Call and dispatches
them to ScriptedAlarmEngine so OPC UA HMI clients can acknowledge/confirm scripted alarms
in addition to the existing Admin UI path. Shelve methods deferred (per-instance NodeIds,
not well-known type MethodIds — follow-up task). AlarmEngine is now exposed through
Phase7ComposedSources so the server wire-up passes it to every DriverNodeManager. 13 new
unit tests cover dispatch kernel, identity fallback, batch handling, and error paths.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/Server/ZB.MOM.WW.OtOpcUa.Server/OpcUa/DriverNodeManager.cs

@@ -5,10 +5,15 @@ using Opc.Ua.Server;
 using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
 using ZB.MOM.WW.OtOpcUa.Core.Authorization;
 using ZB.MOM.WW.OtOpcUa.Core.Resilience;
+using ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms;
 using ZB.MOM.WW.OtOpcUa.Server.Alarms;
 using ZB.MOM.WW.OtOpcUa.Server.History;
 using ZB.MOM.WW.OtOpcUa.Server.Security;
 using DriverWriteRequest = ZB.MOM.WW.OtOpcUa.Core.Abstractions.WriteRequest;
+// AlarmConditionState exists in both Opc.Ua (the OPC UA stack's node-state class) and
+// ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms (the engine's persisted-state record). Alias the
+// OPC UA one so ConditionSink / VariableHandle keep their existing unqualified usage.
+using OpcAlarmConditionState = Opc.Ua.AlarmConditionState;
 // Core.Abstractions defines a type-named HistoryReadResult (driver-side samples + continuation
 // point) that collides with Opc.Ua.HistoryReadResult (service-layer per-node result). We
 // assign driver-side results to an explicitly-aliased local and construct only the service
@@ -22,7 +27,7 @@ namespace ZB.MOM.WW.OtOpcUa.Server.OpcUa;
 ///     into OPC UA nodes. Implements <see cref="IAddressSpaceBuilder"/> itself so
 ///     <c>GenericDriverNodeManager.BuildAddressSpaceAsync</c> can stream nodes directly into the
 ///     OPC UA server's namespace. PR 15's <c>MarkAsAlarmCondition</c> hook creates a sibling
-///     <see cref="AlarmConditionState"/> node per alarm-flagged variable; subsequent driver
+///     <see cref="OpcAlarmConditionState"/> node per alarm-flagged variable; subsequent driver
 ///     <c>OnAlarmEvent</c> pushes land through the returned sink to drive Activate /
 ///     Acknowledge / Deactivate transitions.
 /// </summary>
@@ -106,12 +111,27 @@ public sealed class DriverNodeManager : CustomNodeManager2, IAddressSpaceBuilder
     private readonly Dictionary<string, ConditionSink> _conditionSinks = new(StringComparer.OrdinalIgnoreCase);
     private EventHandler<AlarmConditionTransition>? _alarmTransitionHandler;
 
+    // Task #24 — Phase 7 Gap 1: route OPC UA Part 9 Acknowledge / Confirm method calls on
+    // scripted alarm condition nodes to the ScriptedAlarmEngine so the engine state machine
+    // advances with the authenticated principal. When null, scripted-alarm method calls fall
+    // through to the stack's built-in handler (which updates the OPC UA node but does not
+    // reach the engine — the pre-task-24 gap).
+    //
+    // _scriptedAlarmIdByConditionNodeId maps the condition node's string identifier
+    // (e.g. "sal-abc123.Condition") → the ScriptedAlarmId the engine addresses by
+    // (e.g. "sal-abc123"). Populated in MarkAsAlarmCondition when the parent variable
+    // carries NodeSourceKind.ScriptedAlarm.
+    private readonly ScriptedAlarmEngine? _scriptedAlarmEngine;
+    private readonly Dictionary<string, string> _scriptedAlarmIdByConditionNodeId
+        = new(StringComparer.OrdinalIgnoreCase);
+
     public DriverNodeManager(IServerInternal server, ApplicationConfiguration configuration,
         IDriver driver, CapabilityInvoker invoker, ILogger<DriverNodeManager> logger,
         AuthorizationGate? authzGate = null, NodeScopeResolver? scopeResolver = null,
         IReadable? virtualReadable = null, IReadable? scriptedAlarmReadable = null,
         IHistoryRouter? historyRouter = null,
-        AlarmConditionService? alarmService = null)
+        AlarmConditionService? alarmService = null,
+        ScriptedAlarmEngine? scriptedAlarmEngine = null)
         : base(server, configuration, namespaceUris: $"urn:OtOpcUa:{driver.DriverInstanceId}")
     {
         _driver = driver;
@@ -125,6 +145,7 @@ public sealed class DriverNodeManager : CustomNodeManager2, IAddressSpaceBuilder
         _scriptedAlarmReadable = scriptedAlarmReadable;
         _historyRouter = historyRouter;
         _alarmService = alarmService;
+        _scriptedAlarmEngine = scriptedAlarmEngine;
         _logger = logger;
 
         if (_alarmService is not null)
@@ -601,9 +622,116 @@ public sealed class DriverNodeManager : CustomNodeManager2, IAddressSpaceBuilder
         IList<ServiceResult> errors)
     {
         GateCallMethodRequests(methodsToCall, errors, context.UserIdentity, _authzGate, _scopeResolver);
+
+        // Task #24 — Phase 7 Gap 1: route Part 9 Acknowledge / Confirm calls that target
+        // scripted alarm condition nodes directly to the ScriptedAlarmEngine. The engine
+        // advances its Part 9 state machine with the authenticated principal (audit
+        // requirement), persists state, and emits the transition event through
+        // ScriptedAlarmSource so OPC UA alarm subscribers see the correct AckedState /
+        // ConfirmedState change. base.Call is skipped for handled slots so the stack's
+        // built-in handler (which updates the OPC UA node but doesn't call the engine)
+        // does not double-fire.
+        if (_scriptedAlarmEngine is not null)
+        {
+            RouteScriptedAlarmMethodCalls(context.UserIdentity, methodsToCall, results, errors,
+                _scriptedAlarmEngine, _scriptedAlarmIdByConditionNodeId);
+        }
+
         base.Call(context, methodsToCall, results, errors);
     }
 
+    /// <summary>
+    ///     Intercepts Part 9 Acknowledge / Confirm <see cref="CallMethodRequest"/> slots that
+    ///     target scripted alarm condition nodes and routes them to the
+    ///     <see cref="ScriptedAlarmEngine"/>. Slots that are handled have their
+    ///     <paramref name="errors"/> entry set to <see cref="ServiceResult.Good"/> and are
+    ///     not touched by the caller's subsequent <c>base.Call</c> invocation.
+    /// </summary>
+    /// <remarks>
+    ///     <para>
+    ///         The OPC UA Part 9 Acknowledge method signature is:
+    ///         InputArguments[0] = EventId (ByteString, ignored — scripted alarms identify by
+    ///         ConditionId, not EventId), InputArguments[1] = Comment (LocalizedText).
+    ///         Confirm has the same shape. Missing or null comment is treated as empty string.
+    ///     </para>
+    ///     <para>
+    ///         User identity is extracted from <paramref name="userIdentity"/>'s
+    ///         <c>DisplayName</c>; when absent (anonymous session) the fallback is
+    ///         <c>"opcua-client"</c> so every audit entry carries an identity. Authenticated
+    ///         LDAP sessions populate DisplayName during <c>OtOpcUaServer.OnImpersonateUser</c>.
+    ///     </para>
+    ///     <para>
+    ///         Extracted as a pure function for unit-testability — all dependencies are
+    ///         passed explicitly; no closed-over state. The caller passes
+    ///         <c>context.UserIdentity</c> from the <see cref="Call"/> override.
+    ///     </para>
+    /// </remarks>
+    internal static void RouteScriptedAlarmMethodCalls(
+        IUserIdentity? userIdentity,
+        IList<CallMethodRequest> methodsToCall,
+        IList<CallMethodResult> results,
+        IList<ServiceResult> errors,
+        ScriptedAlarmEngine engine,
+        IReadOnlyDictionary<string, string> conditionIdToAlarmId)
+    {
+        var user = userIdentity?.DisplayName;
+        if (string.IsNullOrWhiteSpace(user)) user = "opcua-client";
+
+        for (var i = 0; i < methodsToCall.Count; i++)
+        {
+            // Skip slots already errored (gate denied or pre-populated by the stack).
+            if (errors[i] is not null && ServiceResult.IsBad(errors[i])) continue;
+
+            var request = methodsToCall[i];
+
+            // Only handle the two well-known Part 9 method ids.
+            var isAcknowledge = request.MethodId == MethodIds.AcknowledgeableConditionType_Acknowledge;
+            var isConfirm = request.MethodId == MethodIds.AcknowledgeableConditionType_Confirm;
+            if (!isAcknowledge && !isConfirm) continue;
+
+            // ObjectId must be a string identifier so we can look it up in the index.
+            if (request.ObjectId.Identifier is not string conditionKey) continue;
+
+            if (!conditionIdToAlarmId.TryGetValue(conditionKey, out var alarmId)) continue;
+
+            // Extract the operator comment from InputArguments[1] (LocalizedText).
+            // InputArguments[0] is EventId (ByteString) — we address by alarmId, not EventId.
+            // InputArguments elements are Variant-boxed values; unbox via .Value before casting.
+            string? comment = null;
+            if (request.InputArguments?.Count >= 2
+                && request.InputArguments[1].Value is LocalizedText lt)
+                comment = lt.Text;
+
+            try
+            {
+                if (isAcknowledge)
+                    engine.AcknowledgeAsync(alarmId, user, comment, CancellationToken.None)
+                        .GetAwaiter().GetResult();
+                else
+                    engine.ConfirmAsync(alarmId, user, comment, CancellationToken.None)
+                        .GetAwaiter().GetResult();
+
+                // Mark the slot as handled so base.Call skips it. A pre-populated Good
+                // result (not null and not Bad) is the signal the base class uses to
+                // skip per-slot dispatch — set StatusCode to Good explicitly.
+                results[i] = new CallMethodResult { StatusCode = StatusCodes.Good };
+                errors[i] = ServiceResult.Good;
+            }
+            catch (ArgumentException ex)
+            {
+                // Unknown alarmId or invalid state (e.g. already acknowledged) — surface
+                // as BadInvalidArgument so the OPC UA client sees a meaningful status.
+                errors[i] = new ServiceResult(StatusCodes.BadInvalidArgument,
+                    ex.Message, ex.Message);
+            }
+            catch (Exception ex)
+            {
+                errors[i] = new ServiceResult(StatusCodes.BadInternalError,
+                    ex.Message, ex.Message);
+            }
+        }
+    }
+
     /// <summary>
     ///     Pure-function gate for a batch of <see cref="CallMethodRequest"/>. Pre-populates
     ///     <paramref name="errors"/> slots with <see cref="StatusCodes.BadUserAccessDenied"/>
@@ -774,7 +902,7 @@ public sealed class DriverNodeManager : CustomNodeManager2, IAddressSpaceBuilder
         {
             lock (_owner.Lock)
             {
-                var alarm = new AlarmConditionState(_variable)
+                var alarm = new OpcAlarmConditionState(_variable)
                 {
                     SymbolicName = _variable.BrowseName.Name + "_Condition",
                     ReferenceTypeId = ReferenceTypeIds.HasComponent,
@@ -822,6 +950,20 @@ public sealed class DriverNodeManager : CustomNodeManager2, IAddressSpaceBuilder
 
                 var sink = new ConditionSink(_owner, alarm);
 
+                // Task #24 — register the condition nodeId → ScriptedAlarmId mapping so the
+                // Call override can route Acknowledge/Confirm invocations to the engine.
+                // The condition's string identifier is "{FullReference}.Condition"; the engine
+                // addresses alarms by ScriptedAlarmId (= FullReference for scripted alarms,
+                // because EquipmentNodeWalker sets FullName = ScriptedAlarmId on the attr).
+                if (_owner._scriptedAlarmEngine is not null
+                    && _owner._sourceByFullRef.TryGetValue(FullReference, out var varSource)
+                    && varSource == NodeSourceKind.ScriptedAlarm)
+                {
+                    var conditionKey = alarm.NodeId.Identifier?.ToString();
+                    if (!string.IsNullOrEmpty(conditionKey))
+                        _owner._scriptedAlarmIdByConditionNodeId[conditionKey!] = FullReference;
+                }
+
                 // PR 2.3 — when the server-level alarm-condition service is wired, register
                 // this condition with it so the state machine runs server-side. The sink-map
                 // entry routes future TransitionRaised events back to this OPC UA node.
@@ -884,7 +1026,7 @@ public sealed class DriverNodeManager : CustomNodeManager2, IAddressSpaceBuilder
         }
     }
 
-    private sealed class ConditionSink(DriverNodeManager owner, AlarmConditionState alarm)
+    private sealed class ConditionSink(DriverNodeManager owner, OpcAlarmConditionState alarm)
         : IAlarmConditionSink
     {
         public void OnTransition(AlarmEventArgs args)

src/Server/ZB.MOM.WW.OtOpcUa.Server/OpcUa/OpcUaApplicationHost.cs

@@ -5,6 +5,7 @@ using ZB.MOM.WW.OtOpcUa.Configuration.LocalCache;
 using ZB.MOM.WW.OtOpcUa.Core.Hosting;
 using ZB.MOM.WW.OtOpcUa.Core.OpcUa;
 using ZB.MOM.WW.OtOpcUa.Core.Resilience;
+using ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms;
 using ZB.MOM.WW.OtOpcUa.Server.Alarms;
 using ZB.MOM.WW.OtOpcUa.Server.History;
 using ZB.MOM.WW.OtOpcUa.Server.Observability;
@@ -41,6 +42,11 @@ public sealed class OpcUaApplicationHost : IAsyncDisposable
     // the host has been DI-constructed (task #246).
     private ZB.MOM.WW.OtOpcUa.Core.Abstractions.IReadable? _virtualReadable;
     private ZB.MOM.WW.OtOpcUa.Core.Abstractions.IReadable? _scriptedAlarmReadable;
+    // Task #24 — Phase 7 Gap 1. The engine is passed to every DriverNodeManager so OPC UA
+    // Part 9 Acknowledge / Confirm method calls on scripted alarm condition nodes reach the
+    // engine with the authenticated principal instead of falling through to the stack's
+    // default Part 9 no-op handler.
+    private ScriptedAlarmEngine? _scriptedAlarmEngine;
 
     // PR 1+2.W — server-level singletons. Threaded through to OtOpcUaServer + every
     // DriverNodeManager. Default null preserves existing test construction sites that
@@ -90,21 +96,31 @@ public sealed class OpcUaApplicationHost : IAsyncDisposable
     public OtOpcUaServer? Server => _server;
 
     /// <summary>
-    ///     Late-bind the Phase 7 engine-backed <c>IReadable</c> sources. Must be
-    ///     called BEFORE <see cref="StartAsync"/> — once the OPC UA server starts, the
-    ///     <see cref="OtOpcUaServer"/> ctor captures the field values + per-node
-    ///     <see cref="DriverNodeManager"/>s are constructed. Calling this after start has
-    ///     no effect on already-materialized node managers.
+    ///     Late-bind the Phase 7 engine-backed <c>IReadable</c> sources and the
+    ///     <see cref="ScriptedAlarmEngine"/>. Must be called BEFORE <see cref="StartAsync"/>
+    ///     — once the OPC UA server starts, the <see cref="OtOpcUaServer"/> ctor captures
+    ///     the field values + per-node <see cref="DriverNodeManager"/>s are constructed.
+    ///     Calling this after start has no effect on already-materialized node managers.
     /// </summary>
+    /// <param name="virtualReadable">Virtual-tag engine read adapter; null when no virtual tags.</param>
+    /// <param name="scriptedAlarmReadable">Scripted-alarm engine read adapter; null when no scripted alarms.</param>
+    /// <param name="alarmEngine">
+    ///     The <see cref="ScriptedAlarmEngine"/> instance (task #24). When non-null,
+    ///     <c>DriverNodeManager</c> routes OPC UA Part 9 Acknowledge/Confirm method calls
+    ///     on scripted alarm condition nodes directly to the engine with the authenticated
+    ///     principal, producing correct audit entries and state-machine transitions.
+    /// </param>
     public void SetPhase7Sources(
         ZB.MOM.WW.OtOpcUa.Core.Abstractions.IReadable? virtualReadable,
-        ZB.MOM.WW.OtOpcUa.Core.Abstractions.IReadable? scriptedAlarmReadable)
+        ZB.MOM.WW.OtOpcUa.Core.Abstractions.IReadable? scriptedAlarmReadable,
+        ScriptedAlarmEngine? alarmEngine = null)
     {
         if (_server is not null)
             throw new InvalidOperationException(
                 "Phase 7 sources must be set before OpcUaApplicationHost.StartAsync; the OtOpcUaServer + DriverNodeManagers have already captured the previous values.");
         _virtualReadable = virtualReadable;
         _scriptedAlarmReadable = scriptedAlarmReadable;
+        _scriptedAlarmEngine = alarmEngine;
     }
 
     /// <summary>
@@ -149,7 +165,8 @@ public sealed class OpcUaApplicationHost : IAsyncDisposable
             tierLookup: _tierLookup, resilienceConfigLookup: _resilienceConfigLookup,
             virtualReadable: _virtualReadable, scriptedAlarmReadable: _scriptedAlarmReadable,
             anonymousRoles: _options.AnonymousRoles,
-            historyRouter: _historyRouter, alarmConditionService: _alarmConditionService);
+            historyRouter: _historyRouter, alarmConditionService: _alarmConditionService,
+            scriptedAlarmEngine: _scriptedAlarmEngine);
         await _application.Start(_server).ConfigureAwait(false);
 
         _logger.LogInformation("OPC UA server started — endpoint={Endpoint} driverCount={Count}",

src/Server/ZB.MOM.WW.OtOpcUa.Server/OpcUa/OtOpcUaServer.cs

@@ -6,6 +6,7 @@ using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
 using ZB.MOM.WW.OtOpcUa.Core.Hosting;
 using ZB.MOM.WW.OtOpcUa.Core.OpcUa;
 using ZB.MOM.WW.OtOpcUa.Core.Resilience;
+using ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms;
 using ZB.MOM.WW.OtOpcUa.Server.Alarms;
 using ZB.MOM.WW.OtOpcUa.Server.History;
 using ZB.MOM.WW.OtOpcUa.Server.Security;
@@ -35,6 +36,9 @@ public sealed class OtOpcUaServer : StandardServer
     // dispatch — identical to pre-Phase-7 behaviour.
     private readonly IReadable? _virtualReadable;
     private readonly IReadable? _scriptedAlarmReadable;
+    // Task #24 — Gap 1. Passed through to every DriverNodeManager so OPC UA Part 9
+    // Acknowledge/Confirm method calls on scripted alarm condition nodes reach the engine.
+    private readonly ScriptedAlarmEngine? _scriptedAlarmEngine;
 
     // PR 1+2.W — server-level singletons shared across every DriverNodeManager.
     // Null when the deployment hasn't opted into the new server-side history routing /
@@ -68,7 +72,8 @@ public sealed class OtOpcUaServer : StandardServer
         IReadable? scriptedAlarmReadable = null,
         IReadOnlyList<string>? anonymousRoles = null,
         IHistoryRouter? historyRouter = null,
-        AlarmConditionService? alarmConditionService = null)
+        AlarmConditionService? alarmConditionService = null,
+        ScriptedAlarmEngine? scriptedAlarmEngine = null)
     {
         _driverHost = driverHost;
         _authenticator = authenticator;
@@ -82,6 +87,7 @@ public sealed class OtOpcUaServer : StandardServer
         _anonymousRoles = anonymousRoles ?? [];
         _historyRouter = historyRouter;
         _alarmConditionService = alarmConditionService;
+        _scriptedAlarmEngine = scriptedAlarmEngine;
         _loggerFactory = loggerFactory;
     }
 
@@ -116,7 +122,8 @@ public sealed class OtOpcUaServer : StandardServer
             var manager = new DriverNodeManager(server, configuration, driver, invoker, logger,
                 authzGate: _authzGate, scopeResolver: _scopeResolver,
                 virtualReadable: _virtualReadable, scriptedAlarmReadable: _scriptedAlarmReadable,
-                historyRouter: _historyRouter, alarmService: _alarmConditionService);
+                historyRouter: _historyRouter, alarmService: _alarmConditionService,
+                scriptedAlarmEngine: _scriptedAlarmEngine);
 
             // The router stays empty after PR 1+2.W — DriverNodeManager's internal
             // LegacyDriverHistoryAdapter handles every driver that still implements

src/Server/ZB.MOM.WW.OtOpcUa.Server/OpcUaServerService.cs

@@ -56,7 +56,8 @@ public sealed class OpcUaServerService(
             // — late binding after server start is rejected with InvalidOperationException.
             // No-op when the generation has no virtual tags or scripted alarms.
             var phase7 = await phase7Composer.PrepareAsync(gen, stoppingToken);
-            applicationHost.SetPhase7Sources(phase7.VirtualReadable, phase7.ScriptedAlarmReadable);
+            applicationHost.SetPhase7Sources(phase7.VirtualReadable, phase7.ScriptedAlarmReadable,
+                phase7.AlarmEngine);
 
             // Phase 6.2 Stream C wiring — build the AuthorizationGate + NodeScopeResolver
             // from the published generation's NodeAcl rows and the populated equipment

src/Server/ZB.MOM.WW.OtOpcUa.Server/Phase7/Phase7EngineComposer.cs

@@ -74,6 +74,7 @@ public static class Phase7EngineComposer
         }
 
         IReadable? alarmReadable = null;
+        ScriptedAlarmEngine? composedAlarmEngine = null;
         if (scriptedAlarms.Count > 0)
         {
             var alarmDefs = ProjectScriptedAlarms(scriptedAlarms, scriptById).ToList();
@@ -89,11 +90,12 @@ public static class Phase7EngineComposer
             // instead of BadNotFound. ScriptedAlarmSource stays registered as IAlarmSource
             // for the event stream; the IReadable is a separate adapter over the same engine.
             alarmReadable = new ScriptedAlarmReadable(alarmEngine);
+            composedAlarmEngine = alarmEngine;
             disposables.Add(alarmEngine);
             disposables.Add(alarmSource);
         }
 
-        return new Phase7ComposedSources(vtSource, alarmReadable, disposables);
+        return new Phase7ComposedSources(vtSource, alarmReadable, disposables, composedAlarmEngine);
     }
 
     internal static IEnumerable<VirtualTagDefinition> ProjectVirtualTags(
@@ -192,10 +194,17 @@ public static class Phase7EngineComposer
 /// <param name="VirtualReadable">Non-null when virtual tags were composed; pass to <c>OpcUaApplicationHost.virtualReadable</c>.</param>
 /// <param name="ScriptedAlarmReadable">Non-null when scripted alarms were composed; pass to <c>OpcUaApplicationHost.scriptedAlarmReadable</c>.</param>
 /// <param name="Disposables">Engine + source instances the caller owns. Dispose on shutdown.</param>
+/// <param name="AlarmEngine">
+///     The <see cref="ScriptedAlarmEngine"/> instance, non-null when scripted alarms were
+///     composed. Passed to <c>OpcUaApplicationHost</c> so <c>DriverNodeManager</c> can
+///     route OPC UA Part 9 Acknowledge / Confirm method invocations directly to the engine
+///     with the authenticated principal (task #24 — Gap 1 of phase-7-status.md).
+/// </param>
 public sealed record Phase7ComposedSources(
     IReadable? VirtualReadable,
     IReadable? ScriptedAlarmReadable,
-    IReadOnlyList<IDisposable> Disposables)
+    IReadOnlyList<IDisposable> Disposables,
+    ScriptedAlarmEngine? AlarmEngine = null)
 {
     public static readonly Phase7ComposedSources Empty =
         new(null, null, Array.Empty<IDisposable>());

tests/Server/ZB.MOM.WW.OtOpcUa.Server.Tests/Phase7/ScriptedAlarmMethodRoutingTests.cs

@@ -0,0 +1,447 @@
+using Microsoft.Extensions.Logging.Abstractions;
+using Opc.Ua;
+using Serilog;
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Configuration.Entities;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+using ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian;
+using ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms;
+using ZB.MOM.WW.OtOpcUa.Core.Scripting;
+using ZB.MOM.WW.OtOpcUa.Server.OpcUa;
+using ZB.MOM.WW.OtOpcUa.Server.Phase7;
+using CoreAlarmConditionState = ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms.AlarmConditionState;
+
+namespace ZB.MOM.WW.OtOpcUa.Server.Tests.Phase7;
+
+/// <summary>
+///     Task #24 — Gap 1 of phase-7-status.md. Covers
+///     <see cref="DriverNodeManager.RouteScriptedAlarmMethodCalls"/> which intercepts
+///     OPC UA Part 9 Acknowledge / Confirm method invocations on scripted alarm condition
+///     nodes and routes them to <see cref="ScriptedAlarmEngine"/>, and the
+///     <see cref="Phase7ComposedSources.AlarmEngine"/> property added to expose the
+///     engine through the composition chain.
+/// </summary>
+[Trait("Category", "Unit")]
+public sealed class ScriptedAlarmMethodRoutingTests
+{
+    // -----------------------------------------------------------------------
+    // Phase7ComposedSources — AlarmEngine property
+    // -----------------------------------------------------------------------
+
+    [Fact]
+    public void Compose_ScriptedAlarm_rows_exposes_AlarmEngine()
+    {
+        var scripts = new[] { ScriptRow("scr-1", "return false;") };
+        var alarms = new[] { AlarmRow("al-1", "scr-1") };
+
+        var result = Phase7EngineComposer.Compose(
+            scripts, [], alarms,
+            upstream: new CachedTagUpstreamSource(),
+            alarmStateStore: new InMemoryAlarmStateStore(),
+            historianSink: NullAlarmHistorianSink.Instance,
+            rootScriptLogger: new LoggerConfiguration().CreateLogger(),
+            loggerFactory: NullLoggerFactory.Instance);
+
+        result.AlarmEngine.ShouldNotBeNull("engine is exposed so the server can route method calls");
+        result.ScriptedAlarmReadable.ShouldNotBeNull();
+        result.Disposables.Count.ShouldBeGreaterThan(0);
+    }
+
+    [Fact]
+    public void Compose_empty_rows_AlarmEngine_is_null()
+    {
+        var result = Phase7EngineComposer.Compose(
+            scripts: [],
+            virtualTags: [],
+            scriptedAlarms: [],
+            upstream: new CachedTagUpstreamSource(),
+            alarmStateStore: new InMemoryAlarmStateStore(),
+            historianSink: NullAlarmHistorianSink.Instance,
+            rootScriptLogger: new LoggerConfiguration().CreateLogger(),
+            loggerFactory: NullLoggerFactory.Instance);
+
+        result.ShouldBeSameAs(Phase7ComposedSources.Empty);
+        result.AlarmEngine.ShouldBeNull("empty composition returns the Empty sentinel with all-null engines");
+    }
+
+    [Fact]
+    public void Compose_VirtualTag_only_AlarmEngine_is_null()
+    {
+        var scripts = new[] { ScriptRow("scr-1", "return 1;") };
+        var vtags = new[] { VtRow("vt-1", "scr-1") };
+
+        var result = Phase7EngineComposer.Compose(
+            scripts, vtags, [],
+            upstream: new CachedTagUpstreamSource(),
+            alarmStateStore: new InMemoryAlarmStateStore(),
+            historianSink: NullAlarmHistorianSink.Instance,
+            rootScriptLogger: new LoggerConfiguration().CreateLogger(),
+            loggerFactory: NullLoggerFactory.Instance);
+
+        result.AlarmEngine.ShouldBeNull("no scripted alarms → alarm engine is null");
+        result.VirtualReadable.ShouldNotBeNull();
+    }
+
+    // -----------------------------------------------------------------------
+    // RouteScriptedAlarmMethodCalls — pure-function dispatch kernel
+    // -----------------------------------------------------------------------
+
+    /// <summary>
+    ///     Builds a loaded ScriptedAlarmEngine with the given alarm IDs.
+    ///     All predicates return <c>false</c> so the alarm starts Inactive.
+    /// </summary>
+    private static ScriptedAlarmEngine BuildEngine(params string[] alarmIds)
+    {
+        var upstream = new CachedTagUpstreamSource();
+        var logger = new LoggerConfiguration().CreateLogger();
+        var factory = new ScriptLoggerFactory(logger);
+        var engine = new ScriptedAlarmEngine(upstream, new InMemoryAlarmStateStore(), factory, logger);
+        var defs = alarmIds.Select(id => new ScriptedAlarmDefinition(
+            AlarmId: id,
+            EquipmentPath: "/eq",
+            AlarmName: id,
+            Kind: AlarmKind.LimitAlarm,
+            Severity: AlarmSeverity.Medium,
+            MessageTemplate: "msg",
+            PredicateScriptSource: "return false;")).ToList();
+        engine.LoadAsync(defs, CancellationToken.None).GetAwaiter().GetResult();
+        return engine;
+    }
+
+    /// <summary>
+    ///     Builds a loaded ScriptedAlarmEngine where the named alarm starts Active
+    ///     (predicate = return true) so subsequent Acknowledge tests have an
+    ///     Unacknowledged state to advance.
+    /// </summary>
+    private static ScriptedAlarmEngine BuildActiveEngine(string alarmId)
+    {
+        var upstream = new CachedTagUpstreamSource();
+        var logger = new LoggerConfiguration().CreateLogger();
+        var factory = new ScriptLoggerFactory(logger);
+        var engine = new ScriptedAlarmEngine(upstream, new InMemoryAlarmStateStore(), factory, logger);
+        var defs = new List<ScriptedAlarmDefinition>
+        {
+            new(AlarmId: alarmId,
+                EquipmentPath: "/eq",
+                AlarmName: alarmId,
+                Kind: AlarmKind.LimitAlarm,
+                Severity: AlarmSeverity.Medium,
+                MessageTemplate: "msg",
+                PredicateScriptSource: "return true;"),
+        };
+        engine.LoadAsync(defs, CancellationToken.None).GetAwaiter().GetResult();
+        return engine;
+    }
+
+    private static IUserIdentity? MakeIdentity(string? displayName)
+        => displayName is null ? null : new NamedUserIdentity(displayName);
+
+    private static CallMethodRequest AcknowledgeRequest(string conditionNodeId, string? comment = null)
+        => new()
+        {
+            ObjectId = new NodeId(conditionNodeId, 2),
+            MethodId = MethodIds.AcknowledgeableConditionType_Acknowledge,
+            InputArguments = new VariantCollection
+            {
+                new Variant(new byte[] { 1, 2, 3 }), // EventId (ByteString) — ignored
+                new Variant(new LocalizedText(comment ?? string.Empty)),
+            },
+        };
+
+    private static CallMethodRequest ConfirmRequest(string conditionNodeId, string? comment = null)
+        => new()
+        {
+            ObjectId = new NodeId(conditionNodeId, 2),
+            MethodId = MethodIds.AcknowledgeableConditionType_Confirm,
+            InputArguments = new VariantCollection
+            {
+                new Variant(new byte[] { 1, 2, 3 }), // EventId (ByteString) — ignored
+                new Variant(new LocalizedText(comment ?? string.Empty)),
+            },
+        };
+
+    private static CallMethodRequest GenericRequest(string objectNodeId)
+        => new()
+        {
+            ObjectId = new NodeId(objectNodeId, 2),
+            MethodId = new NodeId("driver-method", 2),
+        };
+
+    private static Dictionary<string, string> Index(params (string condId, string alarmId)[] entries)
+        => entries.ToDictionary(e => e.condId, e => e.alarmId, StringComparer.OrdinalIgnoreCase);
+
+    // ---- no-op paths -------------------------------------------------------
+
+    [Fact]
+    public void No_index_entries_leaves_all_slots_untouched()
+    {
+        using var engine = BuildActiveEngine("al-1");
+        var calls = new List<CallMethodRequest>
+        {
+            AcknowledgeRequest("al-1.Condition"),
+        };
+        var results = new List<CallMethodResult> { new CallMethodResult() };
+        var errors = new List<ServiceResult> { null! };
+
+        DriverNodeManager.RouteScriptedAlarmMethodCalls(
+            MakeIdentity("alice"), calls, results, errors, engine,
+            conditionIdToAlarmId: new Dictionary<string, string>());
+
+        errors[0].ShouldBeNull("no matching entry → slot left for base.Call");
+    }
+
+    [Fact]
+    public void Non_alarm_method_id_is_ignored()
+    {
+        using var engine = BuildEngine("al-1");
+        var calls = new List<CallMethodRequest>
+        {
+            GenericRequest("al-1.Condition"),
+        };
+        var results = new List<CallMethodResult> { new CallMethodResult() };
+        var errors = new List<ServiceResult> { null! };
+        var index = Index(("al-1.Condition", "al-1"));
+
+        DriverNodeManager.RouteScriptedAlarmMethodCalls(
+            MakeIdentity("alice"), calls, results, errors, engine, index);
+
+        errors[0].ShouldBeNull("non-Acknowledge/Confirm methods pass through untouched");
+    }
+
+    [Fact]
+    public void Already_errored_slot_is_skipped()
+    {
+        using var engine = BuildActiveEngine("al-1");
+        var calls = new List<CallMethodRequest>
+        {
+            AcknowledgeRequest("al-1.Condition"),
+        };
+        var results = new List<CallMethodResult> { new CallMethodResult() };
+        var priorError = new ServiceResult(StatusCodes.BadUserAccessDenied);
+        var errors = new List<ServiceResult> { priorError };
+        var index = Index(("al-1.Condition", "al-1"));
+
+        DriverNodeManager.RouteScriptedAlarmMethodCalls(
+            MakeIdentity("alice"), calls, results, errors, engine, index);
+
+        // Pre-populated bad error must not be overwritten.
+        errors[0].StatusCode.ShouldBe((StatusCode)StatusCodes.BadUserAccessDenied);
+    }
+
+    // ---- Acknowledge -------------------------------------------------------
+
+    [Fact]
+    public void Acknowledge_on_active_alarm_advances_engine_state()
+    {
+        using var engine = BuildActiveEngine("al-1");
+
+        // Sanity: alarm must start unacknowledged after activation.
+        engine.GetState("al-1")!.Acked.ShouldBe(AlarmAckedState.Unacknowledged);
+
+        var calls = new List<CallMethodRequest> { AcknowledgeRequest("al-1.Condition", "looks ok") };
+        var results = new List<CallMethodResult> { new CallMethodResult() };
+        var errors = new List<ServiceResult> { null! };
+        var index = Index(("al-1.Condition", "al-1"));
+
+        DriverNodeManager.RouteScriptedAlarmMethodCalls(
+            MakeIdentity("ops-user"), calls, results, errors, engine, index);
+
+        errors[0].ShouldNotBeNull();
+        ServiceResult.IsBad(errors[0]).ShouldBeFalse("Acknowledge succeeded");
+        engine.GetState("al-1")!.Acked.ShouldBe(AlarmAckedState.Acknowledged);
+        engine.GetState("al-1")!.LastAckUser.ShouldBe("ops-user");
+        engine.GetState("al-1")!.LastAckComment.ShouldBe("looks ok");
+    }
+
+    [Fact]
+    public void Acknowledge_uses_opcua_client_as_fallback_when_identity_is_null()
+    {
+        using var engine = BuildActiveEngine("al-1");
+
+        var calls = new List<CallMethodRequest> { AcknowledgeRequest("al-1.Condition") };
+        var results = new List<CallMethodResult> { new CallMethodResult() };
+        var errors = new List<ServiceResult> { null! };
+        var index = Index(("al-1.Condition", "al-1"));
+
+        // Pass null identity (anonymous session).
+        DriverNodeManager.RouteScriptedAlarmMethodCalls(
+            userIdentity: null, calls, results, errors, engine, index);
+
+        engine.GetState("al-1")!.LastAckUser.ShouldBe("opcua-client");
+    }
+
+    [Fact]
+    public void Acknowledge_with_no_input_arguments_uses_null_comment()
+    {
+        using var engine = BuildActiveEngine("al-1");
+        // Build a request without InputArguments to simulate a client that omits the comment.
+        var requestNoArgs = new CallMethodRequest
+        {
+            ObjectId = new NodeId("al-1.Condition", 2),
+            MethodId = MethodIds.AcknowledgeableConditionType_Acknowledge,
+        };
+
+        var calls = new List<CallMethodRequest> { requestNoArgs };
+        var results = new List<CallMethodResult> { new CallMethodResult() };
+        var errors = new List<ServiceResult> { null! };
+        var index = Index(("al-1.Condition", "al-1"));
+
+        // Should not throw — comment defaults to null.
+        DriverNodeManager.RouteScriptedAlarmMethodCalls(
+            MakeIdentity("alice"), calls, results, errors, engine, index);
+
+        ServiceResult.IsBad(errors[0]).ShouldBeFalse("Acknowledge without comment succeeds");
+    }
+
+    [Fact]
+    public void Acknowledge_marks_slot_result_as_Good_and_error_as_Good()
+    {
+        using var engine = BuildActiveEngine("al-1");
+
+        var calls = new List<CallMethodRequest> { AcknowledgeRequest("al-1.Condition") };
+        var results = new List<CallMethodResult> { new CallMethodResult() };
+        var errors = new List<ServiceResult> { null! };
+        var index = Index(("al-1.Condition", "al-1"));
+
+        DriverNodeManager.RouteScriptedAlarmMethodCalls(
+            MakeIdentity("alice"), calls, results, errors, engine, index);
+
+        results[0].StatusCode.ShouldBe((StatusCode)StatusCodes.Good);
+        errors[0].ShouldBe(ServiceResult.Good);
+    }
+
+    // ---- Confirm -----------------------------------------------------------
+
+    [Fact]
+    public void Confirm_on_alarm_with_unconfirmed_state_advances_state()
+    {
+        // Build an alarm pre-seeded as Inactive + Acknowledged + Unconfirmed so
+        // ApplyConfirm has a valid transition to execute.
+        var store = new InMemoryAlarmStateStore();
+        var upstream = new CachedTagUpstreamSource();
+        var logger = new LoggerConfiguration().CreateLogger();
+        var factory = new ScriptLoggerFactory(logger);
+        var engine = new ScriptedAlarmEngine(upstream, store, factory, logger);
+
+        var seedState = CoreAlarmConditionState.Fresh("confirm-alarm", DateTime.UtcNow) with
+        {
+            Active = AlarmActiveState.Inactive,
+            Acked = AlarmAckedState.Acknowledged,
+            Confirmed = AlarmConfirmedState.Unconfirmed,
+        };
+        store.SaveAsync(seedState, CancellationToken.None).GetAwaiter().GetResult();
+
+        var defs = new List<ScriptedAlarmDefinition>
+        {
+            new("confirm-alarm", "/eq", "confirm-alarm", AlarmKind.LimitAlarm,
+                AlarmSeverity.Low, "msg", "return false;"),
+        };
+        engine.LoadAsync(defs, CancellationToken.None).GetAwaiter().GetResult();
+
+        engine.GetState("confirm-alarm")!.Confirmed.ShouldBe(AlarmConfirmedState.Unconfirmed);
+
+        var calls = new List<CallMethodRequest>
+        {
+            ConfirmRequest("confirm-alarm.Condition", "all clear"),
+        };
+        var results = new List<CallMethodResult> { new CallMethodResult() };
+        var errors = new List<ServiceResult> { null! };
+        var index = Index(("confirm-alarm.Condition", "confirm-alarm"));
+
+        DriverNodeManager.RouteScriptedAlarmMethodCalls(
+            MakeIdentity("ops-user"), calls, results, errors, engine, index);
+
+        ServiceResult.IsBad(errors[0]).ShouldBeFalse("Confirm succeeded");
+        engine.GetState("confirm-alarm")!.Confirmed.ShouldBe(AlarmConfirmedState.Confirmed);
+        engine.GetState("confirm-alarm")!.LastConfirmUser.ShouldBe("ops-user");
+    }
+
+    // ---- Mixed batches -----------------------------------------------------
+
+    [Fact]
+    public void Mixed_batch_handles_each_slot_independently()
+    {
+        using var engine = BuildActiveEngine("al-1");
+
+        var calls = new List<CallMethodRequest>
+        {
+            AcknowledgeRequest("al-1.Condition"),          // scripted alarm → handled
+            GenericRequest("some-driver-method"),           // non-alarm → pass through
+            AcknowledgeRequest("unknown-alarm.Condition"),  // not in index → pass through
+        };
+        var results = Enumerable.Range(0, 3).Select(_ => new CallMethodResult()).ToList();
+        var errors = new List<ServiceResult> { null!, null!, null! };
+        var index = Index(("al-1.Condition", "al-1")); // only one entry
+
+        DriverNodeManager.RouteScriptedAlarmMethodCalls(
+            MakeIdentity("alice"), calls, results, errors, engine, index);
+
+        // Slot 0: Acknowledge on known scripted alarm → handled with Good result.
+        ServiceResult.IsBad(errors[0]).ShouldBeFalse("scripted alarm Acknowledge handled");
+        engine.GetState("al-1")!.Acked.ShouldBe(AlarmAckedState.Acknowledged);
+
+        // Slot 1: Generic method → left null for base.Call.
+        errors[1].ShouldBeNull("generic method left for base.Call");
+
+        // Slot 2: Unknown alarm id → left null for base.Call.
+        errors[2].ShouldBeNull("unknown condition id left for base.Call");
+    }
+
+    [Fact]
+    public void Unknown_alarm_id_in_engine_returns_BadInvalidArgument()
+    {
+        using var engine = BuildEngine("al-1");
+
+        // The index says al-999 maps to "al-999-engine" but the engine has no such alarm.
+        var calls = new List<CallMethodRequest>
+        {
+            AcknowledgeRequest("al-999.Condition"),
+        };
+        var results = new List<CallMethodResult> { new CallMethodResult() };
+        var errors = new List<ServiceResult> { null! };
+        // Put a deliberately wrong alarmId in the index (engine will throw ArgumentException).
+        var index = Index(("al-999.Condition", "al-999-not-in-engine"));
+
+        DriverNodeManager.RouteScriptedAlarmMethodCalls(
+            MakeIdentity("alice"), calls, results, errors, engine, index);
+
+        ServiceResult.IsBad(errors[0]).ShouldBeTrue("unknown alarm in engine → error result");
+        errors[0].StatusCode.ShouldBe((StatusCode)StatusCodes.BadInvalidArgument);
+    }
+
+    // ---- Phase7ComposedSources helpers -------------------------------------
+
+    private static Script ScriptRow(string id, string source) => new()
+    {
+        ScriptRowId = Guid.NewGuid(), GenerationId = 1,
+        ScriptId = id, Name = id, SourceCode = source, SourceHash = "h",
+    };
+
+    private static VirtualTag VtRow(string id, string scriptId) => new()
+    {
+        VirtualTagRowId = Guid.NewGuid(), GenerationId = 1,
+        VirtualTagId = id, EquipmentId = "eq-1", Name = id,
+        DataType = "Float32", ScriptId = scriptId,
+    };
+
+    private static ScriptedAlarm AlarmRow(string id, string scriptId) => new()
+    {
+        ScriptedAlarmRowId = Guid.NewGuid(), GenerationId = 1,
+        ScriptedAlarmId = id, EquipmentId = "eq-1", Name = id,
+        AlarmType = "LimitAlarm", Severity = 500,
+        MessageTemplate = "x", PredicateScriptId = scriptId,
+    };
+
+    // ---- Fake user identity ------------------------------------------------
+
+    /// <summary>
+    ///     Simple <see cref="UserIdentity"/> with a display name for unit testing.
+    ///     Uses the <c>UserIdentity(username, password)</c> constructor so the base-class
+    ///     <see cref="UserIdentity.DisplayName"/> property returns the supplied name when
+    ///     accessed through the <see cref="IUserIdentity"/> interface.
+    ///     The real production identity is <c>OtOpcUaServer.RoleBasedIdentity</c> which
+    ///     populates DisplayName from the LDAP authentication result.
+    /// </summary>
+    private sealed class NamedUserIdentity(string displayName) : UserIdentity(displayName, "") { }
+}