Phase 7 Stream F — Admin UI for scripts + test harness + historian diagnostics

Adds the draft-editor tab + page surface for authoring Phase 7 virtual tags and
scripted alarms, plus the /alarms/historian operator diagnostics page. Monaco loads
from CDN via a progressive-enhancement JS shim — the textarea works immediately so
the page is functional even if the CDN is unreachable.

## New services (Admin)

- ScriptService — CRUD for Script entity. SHA-256 SourceHash recomputed on save so
  Core.Scripting's CompiledScriptCache hits on re-publish of unchanged source + misses
  when the source actually changes.
- VirtualTagService — CRUD for VirtualTag, with Enabled toggle.
- ScriptedAlarmService — CRUD for ScriptedAlarm + lookup of persistent ScriptedAlarmState
  (logical-id-keyed per plan decision #14).
- ScriptTestHarnessService — pre-publish dry-run. Enforces plan decision #22: only
  inputs the DependencyExtractor identifies can be supplied. Missing / extra synthetic
  inputs surface as dedicated outcomes. Captures SetVirtualTag writes + Serilog events
  from the script so the operator can see both the output + the log output before
  publishing.
- HistorianDiagnosticsService — surfaces the local-process IAlarmHistorianSink state
  on /alarms/historian. Null sink reports Disabled + swallows retry. Live
  SqliteStoreAndForwardSink reports real queue depth + last-error + drain state and
  routes the Retry-dead-lettered button through.

## New UI

- ScriptsTab.razor (inside DraftEditor tabs) — list + create/edit/delete scripts with
  Monaco editor + dependency preview + test-harness run panel showing output + writes
  + log emissions.
- ScriptEditor.razor — reusable Monaco-backed textarea. Loads editor from CDN via
  wwwroot/js/monaco-loader.js. Textarea stays authoritative for Blazor binding; Monaco
  mirrors into it on every keystroke.
- AlarmsHistorian.razor (/alarms/historian) — queue depth + dead-letter depth + drain
  state badge + last-error banner + Retry-dead-lettered button.
- DraftEditor.razor — new "Scripts" tab.

## DI wiring

All five services registered in Program.cs. Null historian sink bound at Admin
composition time (real SqliteStoreAndForwardSink lives in the Server process).

## Tests — 13/13

Phase7ServicesTests covers:
- ScriptService: Add generates logical id + hash, Update recomputes hash on source
  change, Update same-source keeps hash (cache-hit preservation), Delete is idempotent
- VirtualTagService: round-trips trigger flags, Enabled toggle works
- ScriptedAlarmService: HistorizeToAveva defaults true per plan decision #15
- ScriptTestHarness: successful run captures output + writes, rejects missing /
  extra inputs, rejects non-literal paths, compile errors surface as Threw
- HistorianDiagnosticsService: null sink reports Disabled + retry returns 0

ZB.MOM.WW.OtOpcUa.slnx

@@ -5,6 +5,8 @@
         <Project Path="src/ZB.MOM.WW.OtOpcUa.Core/ZB.MOM.WW.OtOpcUa.Core.csproj"/>
         <Project Path="src/ZB.MOM.WW.OtOpcUa.Core.Scripting/ZB.MOM.WW.OtOpcUa.Core.Scripting.csproj"/>
         <Project Path="src/ZB.MOM.WW.OtOpcUa.Core.VirtualTags/ZB.MOM.WW.OtOpcUa.Core.VirtualTags.csproj"/>
+        <Project Path="src/ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms/ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms.csproj"/>
+        <Project Path="src/ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian/ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian.csproj"/>
         <Project Path="src/ZB.MOM.WW.OtOpcUa.Server/ZB.MOM.WW.OtOpcUa.Server.csproj"/>
         <Project Path="src/ZB.MOM.WW.OtOpcUa.Admin/ZB.MOM.WW.OtOpcUa.Admin.csproj"/>
         <Project Path="src/ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Shared/ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Shared.csproj"/>
@@ -30,6 +32,8 @@
         <Project Path="tests/ZB.MOM.WW.OtOpcUa.Core.Tests/ZB.MOM.WW.OtOpcUa.Core.Tests.csproj"/>
         <Project Path="tests/ZB.MOM.WW.OtOpcUa.Core.Scripting.Tests/ZB.MOM.WW.OtOpcUa.Core.Scripting.Tests.csproj"/>
         <Project Path="tests/ZB.MOM.WW.OtOpcUa.Core.VirtualTags.Tests/ZB.MOM.WW.OtOpcUa.Core.VirtualTags.Tests.csproj"/>
+        <Project Path="tests/ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms.Tests/ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms.Tests.csproj"/>
+        <Project Path="tests/ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian.Tests/ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian.Tests.csproj"/>
         <Project Path="tests/ZB.MOM.WW.OtOpcUa.Server.Tests/ZB.MOM.WW.OtOpcUa.Server.Tests.csproj"/>
         <Project Path="tests/ZB.MOM.WW.OtOpcUa.Admin.Tests/ZB.MOM.WW.OtOpcUa.Admin.Tests.csproj"/>
         <Project Path="tests/ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Shared.Tests/ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Shared.Tests.csproj"/>

src/ZB.MOM.WW.OtOpcUa.Admin/Components/Pages/AlarmsHistorian.razor

@@ -0,0 +1,79 @@
+@page "/alarms/historian"
+@using ZB.MOM.WW.OtOpcUa.Admin.Services
+@using ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian
+@inject HistorianDiagnosticsService Diag
+
+<h1>Alarm historian</h1>
+<p class="text-muted">Local store-and-forward queue that ships alarm events to Aveva Historian via Galaxy.Host.</p>
+
+<div class="card mb-3">
+    <div class="card-body">
+        <div class="row">
+            <div class="col-md-3">
+                <small class="text-muted">Drain state</small>
+                <h4><span class="badge @BadgeFor(_status.DrainState)">@_status.DrainState</span></h4>
+            </div>
+            <div class="col-md-3">
+                <small class="text-muted">Queue depth</small>
+                <h4>@_status.QueueDepth.ToString("N0")</h4>
+            </div>
+            <div class="col-md-3">
+                <small class="text-muted">Dead-letter depth</small>
+                <h4 class="@(_status.DeadLetterDepth > 0 ? "text-warning" : "")">@_status.DeadLetterDepth.ToString("N0")</h4>
+            </div>
+            <div class="col-md-3">
+                <small class="text-muted">Last success</small>
+                <h4>@(_status.LastSuccessUtc?.ToString("u") ?? "—")</h4>
+            </div>
+        </div>
+
+        @if (!string.IsNullOrEmpty(_status.LastError))
+        {
+            <div class="alert alert-warning mt-3 mb-0">
+                <strong>Last error:</strong> @_status.LastError
+            </div>
+        }
+    </div>
+</div>
+
+<div class="d-flex gap-2">
+    <button class="btn btn-outline-secondary" @onclick="RefreshAsync">Refresh</button>
+    <button class="btn btn-warning" disabled="@(_status.DeadLetterDepth == 0)" @onclick="RetryDeadLetteredAsync">
+        Retry dead-lettered (@_status.DeadLetterDepth)
+    </button>
+</div>
+
+@if (_retryResult is not null)
+{
+    <div class="alert alert-success mt-3">Requeued @_retryResult row(s) for retry.</div>
+}
+
+@code {
+    private HistorianSinkStatus _status = new(0, 0, null, null, null, HistorianDrainState.Disabled);
+    private int? _retryResult;
+
+    protected override void OnInitialized() => _status = Diag.GetStatus();
+
+    private Task RefreshAsync()
+    {
+        _status = Diag.GetStatus();
+        _retryResult = null;
+        return Task.CompletedTask;
+    }
+
+    private Task RetryDeadLetteredAsync()
+    {
+        _retryResult = Diag.TryRetryDeadLettered();
+        _status = Diag.GetStatus();
+        return Task.CompletedTask;
+    }
+
+    private static string BadgeFor(HistorianDrainState s) => s switch
+    {
+        HistorianDrainState.Idle => "bg-success",
+        HistorianDrainState.Draining => "bg-info",
+        HistorianDrainState.BackingOff => "bg-warning text-dark",
+        HistorianDrainState.Disabled => "bg-secondary",
+        _ => "bg-secondary",
+    };
+}

src/ZB.MOM.WW.OtOpcUa.Admin/Components/Pages/Clusters/DraftEditor.razor

@@ -23,6 +23,7 @@
     <li class="nav-item"><button class="nav-link @Active("namespaces")" @onclick='() => _tab = "namespaces"'>Namespaces</button></li>
     <li class="nav-item"><button class="nav-link @Active("drivers")" @onclick='() => _tab = "drivers"'>Drivers</button></li>
     <li class="nav-item"><button class="nav-link @Active("acls")" @onclick='() => _tab = "acls"'>ACLs</button></li>
+    <li class="nav-item"><button class="nav-link @Active("scripts")" @onclick='() => _tab = "scripts"'>Scripts</button></li>
 </ul>
 
 <div class="row">
@@ -32,6 +33,7 @@
         else if (_tab == "namespaces") { <NamespacesTab GenerationId="@GenerationId" ClusterId="@ClusterId"/> }
         else if (_tab == "drivers") { <DriversTab GenerationId="@GenerationId" ClusterId="@ClusterId"/> }
         else if (_tab == "acls") { <AclsTab GenerationId="@GenerationId" ClusterId="@ClusterId"/> }
+        else if (_tab == "scripts") { <ScriptsTab GenerationId="@GenerationId" ClusterId="@ClusterId"/> }
     </div>
     <div class="col-md-4">
         <div class="card sticky-top">

src/ZB.MOM.WW.OtOpcUa.Admin/Components/Pages/Clusters/ScriptEditor.razor

@@ -0,0 +1,41 @@
+@using Microsoft.AspNetCore.Components.Web
+@inject IJSRuntime JS
+
+@*
+    Monaco-backed C# code editor (Phase 7 Stream F). Progressive enhancement:
+    textarea renders immediately, Monaco mounts via JS interop after first render.
+    Monaco script tags are loaded once from the parent layout (wwwroot/js/monaco-loader.js
+    pulls the CDN bundle).
+
+    Stream F keeps the interop surface small — bind `Source` two-way, and the parent
+    tab re-renders on change for the dependency preview. The test-harness button
+    lives in the parent so one editor can drive multiple script types.
+*@
+
+<div class="script-editor">
+    <textarea class="form-control font-monospace" rows="14" spellcheck="false"
+              @bind="Source" @bind:event="oninput" id="@_editorId">@Source</textarea>
+</div>
+
+@code {
+    [Parameter] public string Source { get; set; } = string.Empty;
+    [Parameter] public EventCallback<string> SourceChanged { get; set; }
+
+    private readonly string _editorId = $"script-editor-{Guid.NewGuid():N}";
+
+    protected override async Task OnAfterRenderAsync(bool firstRender)
+    {
+        if (firstRender)
+        {
+            try
+            {
+                await JS.InvokeVoidAsync("otOpcUaScriptEditor.attach", _editorId);
+            }
+            catch (JSException)
+            {
+                // Monaco bundle not yet loaded on this page — textarea fallback is
+                // still functional.
+            }
+        }
+    }
+}

src/ZB.MOM.WW.OtOpcUa.Admin/Components/Pages/Clusters/ScriptsTab.razor

@@ -0,0 +1,224 @@
+@using ZB.MOM.WW.OtOpcUa.Admin.Services
+@using ZB.MOM.WW.OtOpcUa.Configuration.Entities
+@using ZB.MOM.WW.OtOpcUa.Core.Abstractions
+@using ZB.MOM.WW.OtOpcUa.Core.Scripting
+@inject ScriptService ScriptSvc
+@inject ScriptTestHarnessService Harness
+
+<div class="d-flex justify-content-between align-items-center mb-3">
+    <div>
+        <h4 class="mb-0">Scripts</h4>
+        <small class="text-muted">C# (Roslyn). Used by virtual tags + scripted alarms.</small>
+    </div>
+    <button class="btn btn-primary" @onclick="StartNew">+ New script</button>
+</div>
+
+<script src="/js/monaco-loader.js"></script>
+
+@if (_loading) { <p class="text-muted">Loading…</p> }
+else if (_scripts.Count == 0 && _editing is null)
+{
+    <div class="alert alert-info">No scripts yet in this draft.</div>
+}
+else
+{
+    <div class="row">
+        <div class="col-md-4">
+            <div class="list-group">
+                @foreach (var s in _scripts)
+                {
+                    <button class="list-group-item list-group-item-action @(_editing?.ScriptId == s.ScriptId ? "active" : "")"
+                            @onclick="() => Open(s)">
+                        <strong>@s.Name</strong>
+                        <div class="small text-muted font-monospace">@s.ScriptId</div>
+                    </button>
+                }
+            </div>
+        </div>
+        <div class="col-md-8">
+            @if (_editing is not null)
+            {
+                <div class="card">
+                    <div class="card-header d-flex justify-content-between align-items-center">
+                        <strong>@(_isNew ? "New script" : _editing.Name)</strong>
+                        <div>
+                            @if (!_isNew)
+                            {
+                                <button class="btn btn-sm btn-outline-danger me-2" @onclick="DeleteAsync">Delete</button>
+                            }
+                            <button class="btn btn-sm btn-primary" disabled="@_busy" @onclick="SaveAsync">Save</button>
+                        </div>
+                    </div>
+                    <div class="card-body">
+                        <div class="mb-2">
+                            <label class="form-label">Name</label>
+                            <input class="form-control" @bind="_editing.Name"/>
+                        </div>
+                        <label class="form-label">Source</label>
+                        <ScriptEditor @bind-Source="_editing.SourceCode"/>
+
+                        <div class="mt-3">
+                            <button class="btn btn-sm btn-outline-secondary" @onclick="PreviewDependencies">Analyze dependencies</button>
+                            <button class="btn btn-sm btn-outline-info ms-2" @onclick="RunHarnessAsync" disabled="@_harnessBusy">Run test harness</button>
+                        </div>
+
+                        @if (_dependencies is not null)
+                        {
+                            <div class="mt-3">
+                                <strong>Inferred reads</strong>
+                                @if (_dependencies.Reads.Count == 0) { <span class="text-muted ms-2">none</span> }
+                                else
+                                {
+                                    <ul class="mb-1">
+                                        @foreach (var r in _dependencies.Reads) { <li><code>@r</code></li> }
+                                    </ul>
+                                }
+                                <strong>Inferred writes</strong>
+                                @if (_dependencies.Writes.Count == 0) { <span class="text-muted ms-2">none</span> }
+                                else
+                                {
+                                    <ul class="mb-1">
+                                        @foreach (var w in _dependencies.Writes) { <li><code>@w</code></li> }
+                                    </ul>
+                                }
+                                @if (_dependencies.Rejections.Count > 0)
+                                {
+                                    <div class="alert alert-danger mt-2">
+                                        <strong>Non-literal paths rejected:</strong>
+                                        <ul class="mb-0">
+                                            @foreach (var r in _dependencies.Rejections) { <li>@r.Message</li> }
+                                        </ul>
+                                    </div>
+                                }
+                            </div>
+                        }
+
+                        @if (_testResult is not null)
+                        {
+                            <div class="mt-3 border-top pt-3">
+                                <strong>Harness result:</strong> <span class="badge bg-secondary">@_testResult.Outcome</span>
+                                @if (_testResult.Outcome == ScriptTestOutcome.Success)
+                                {
+                                    <div>Output: <code>@(_testResult.Output?.ToString() ?? "null")</code></div>
+                                    @if (_testResult.Writes.Count > 0)
+                                    {
+                                        <div class="mt-1"><strong>Writes:</strong>
+                                            <ul class="mb-0">
+                                                @foreach (var kv in _testResult.Writes) { <li><code>@kv.Key</code> = <code>@(kv.Value?.ToString() ?? "null")</code></li> }
+                                            </ul>
+                                        </div>
+                                    }
+                                }
+                                @if (_testResult.Errors.Count > 0)
+                                {
+                                    <div class="alert alert-warning mt-2 mb-0">
+                                        @foreach (var e in _testResult.Errors) { <div>@e</div> }
+                                    </div>
+                                }
+                                @if (_testResult.LogEvents.Count > 0)
+                                {
+                                    <div class="mt-2"><strong>Script log output:</strong>
+                                        <ul class="small mb-0">
+                                            @foreach (var e in _testResult.LogEvents) { <li>[@e.Level] @e.RenderMessage()</li> }
+                                        </ul>
+                                    </div>
+                                }
+                            </div>
+                        }
+                    </div>
+                </div>
+            }
+        </div>
+    </div>
+}
+
+@code {
+    [Parameter] public long GenerationId { get; set; }
+    [Parameter] public string ClusterId { get; set; } = string.Empty;
+
+    private bool _loading = true;
+    private bool _busy;
+    private bool _harnessBusy;
+    private bool _isNew;
+    private List<Script> _scripts = [];
+    private Script? _editing;
+    private DependencyExtractionResult? _dependencies;
+    private ScriptTestResult? _testResult;
+
+    protected override async Task OnParametersSetAsync()
+    {
+        _loading = true;
+        _scripts = await ScriptSvc.ListAsync(GenerationId, CancellationToken.None);
+        _loading = false;
+    }
+
+    private void Open(Script s)
+    {
+        _editing = new Script
+        {
+            ScriptRowId = s.ScriptRowId, GenerationId = s.GenerationId,
+            ScriptId = s.ScriptId, Name = s.Name, SourceCode = s.SourceCode,
+            SourceHash = s.SourceHash, Language = s.Language,
+        };
+        _isNew = false;
+        _dependencies = null;
+        _testResult = null;
+    }
+
+    private void StartNew()
+    {
+        _editing = new Script
+        {
+            GenerationId = GenerationId, ScriptId = "",
+            Name = "new-script", SourceCode = "return 0;", SourceHash = "",
+        };
+        _isNew = true;
+        _dependencies = null;
+        _testResult = null;
+    }
+
+    private async Task SaveAsync()
+    {
+        if (_editing is null) return;
+        _busy = true;
+        try
+        {
+            if (_isNew)
+                await ScriptSvc.AddAsync(GenerationId, _editing.Name, _editing.SourceCode, CancellationToken.None);
+            else
+                await ScriptSvc.UpdateAsync(GenerationId, _editing.ScriptId, _editing.Name, _editing.SourceCode, CancellationToken.None);
+            _scripts = await ScriptSvc.ListAsync(GenerationId, CancellationToken.None);
+            _isNew = false;
+        }
+        finally { _busy = false; }
+    }
+
+    private async Task DeleteAsync()
+    {
+        if (_editing is null || _isNew) return;
+        await ScriptSvc.DeleteAsync(GenerationId, _editing.ScriptId, CancellationToken.None);
+        _editing = null;
+        _scripts = await ScriptSvc.ListAsync(GenerationId, CancellationToken.None);
+    }
+
+    private void PreviewDependencies()
+    {
+        if (_editing is null) return;
+        _dependencies = DependencyExtractor.Extract(_editing.SourceCode);
+    }
+
+    private async Task RunHarnessAsync()
+    {
+        if (_editing is null) return;
+        _harnessBusy = true;
+        try
+        {
+            _dependencies ??= DependencyExtractor.Extract(_editing.SourceCode);
+            var inputs = new Dictionary<string, DataValueSnapshot>();
+            foreach (var read in _dependencies.Reads)
+                inputs[read] = new DataValueSnapshot(0.0, 0u, DateTime.UtcNow, DateTime.UtcNow);
+            _testResult = await Harness.RunVirtualTagAsync(_editing.SourceCode, inputs, CancellationToken.None);
+        }
+        finally { _harnessBusy = false; }
+    }
+}

src/ZB.MOM.WW.OtOpcUa.Admin/Program.cs

@@ -57,6 +57,18 @@ builder.Services.AddScoped<EquipmentImportBatchService>();
 builder.Services.AddScoped<ZB.MOM.WW.OtOpcUa.Configuration.Services.ILdapGroupRoleMappingService,
     ZB.MOM.WW.OtOpcUa.Configuration.Services.LdapGroupRoleMappingService>();
 
+// Phase 7 Stream F — scripting + virtual tag + scripted alarm draft services, test
+// harness, and historian diagnostics. The historian sink is the Null variant here —
+// the real SqliteStoreAndForwardSink lives in the server process. Admin reads status
+// from whichever sink is provided at composition time.
+builder.Services.AddScoped<ScriptService>();
+builder.Services.AddScoped<VirtualTagService>();
+builder.Services.AddScoped<ScriptedAlarmService>();
+builder.Services.AddScoped<ScriptTestHarnessService>();
+builder.Services.AddScoped<HistorianDiagnosticsService>();
+builder.Services.AddSingleton<ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian.IAlarmHistorianSink>(
+    ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian.NullAlarmHistorianSink.Instance);
+
 // Cert-trust management — reads the OPC UA server's PKI store root so rejected client certs
 // can be promoted to trusted via the Admin UI. Singleton: no per-request state, just
 // filesystem operations.

src/ZB.MOM.WW.OtOpcUa.Admin/Services/HistorianDiagnosticsService.cs

@@ -0,0 +1,32 @@
+using ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian;
+
+namespace ZB.MOM.WW.OtOpcUa.Admin.Services;
+
+/// <summary>
+///     Surfaces the local-node historian queue health on the Admin UI's
+///     <c>/alarms/historian</c> diagnostics page (Phase 7 plan decisions #16/#21).
+///     Exposes queue depth / drain state / last-error, and lets the operator retry
+///     dead-lettered rows without restarting the node.
+/// </summary>
+/// <remarks>
+///     The sink injected here is the server-process <see cref="IAlarmHistorianSink"/>.
+///     When <see cref="NullAlarmHistorianSink"/> is bound (historian disabled for this
+///     deployment), <see cref="TryRetryDeadLettered"/> silently returns 0 and
+///     <see cref="GetStatus"/> reports <see cref="HistorianDrainState.Disabled"/>.
+/// </remarks>
+public sealed class HistorianDiagnosticsService(IAlarmHistorianSink sink)
+{
+    public HistorianSinkStatus GetStatus() => sink.GetStatus();
+
+    /// <summary>
+    ///     Operator action from the UI's "Retry dead-lettered" button. Returns the number
+    ///     of rows revived so the UI can flash a confirmation. When the live sink doesn't
+    ///     implement retry (test doubles, Null sink), returns 0.
+    /// </summary>
+    public int TryRetryDeadLettered()
+    {
+        if (sink is SqliteStoreAndForwardSink concrete)
+            return concrete.RetryDeadLettered();
+        return 0;
+    }
+}

src/ZB.MOM.WW.OtOpcUa.Admin/Services/ScriptService.cs

@@ -0,0 +1,66 @@
+using System.Security.Cryptography;
+using System.Text;
+using Microsoft.EntityFrameworkCore;
+using ZB.MOM.WW.OtOpcUa.Configuration;
+using ZB.MOM.WW.OtOpcUa.Configuration.Entities;
+
+namespace ZB.MOM.WW.OtOpcUa.Admin.Services;
+
+/// <summary>
+///     Draft-generation CRUD for <see cref="Script"/> rows — the C# source code referenced
+///     by Phase 7 virtual tags and scripted alarms. <see cref="Script.SourceHash"/> is
+///     recomputed on every save so Core.Scripting's compile cache sees a fresh key when
+///     source changes and reuses the compile when it doesn't.
+/// </summary>
+public sealed class ScriptService(OtOpcUaConfigDbContext db)
+{
+    public Task<List<Script>> ListAsync(long generationId, CancellationToken ct) =>
+        db.Scripts.AsNoTracking()
+            .Where(s => s.GenerationId == generationId)
+            .OrderBy(s => s.Name)
+            .ToListAsync(ct);
+
+    public Task<Script?> GetAsync(long generationId, string scriptId, CancellationToken ct) =>
+        db.Scripts.AsNoTracking()
+            .FirstOrDefaultAsync(s => s.GenerationId == generationId && s.ScriptId == scriptId, ct);
+
+    public async Task<Script> AddAsync(long generationId, string name, string sourceCode, CancellationToken ct)
+    {
+        var s = new Script
+        {
+            GenerationId = generationId,
+            ScriptId = $"scr-{Guid.NewGuid():N}"[..20],
+            Name = name,
+            SourceCode = sourceCode,
+            SourceHash = ComputeHash(sourceCode),
+        };
+        db.Scripts.Add(s);
+        await db.SaveChangesAsync(ct);
+        return s;
+    }
+
+    public async Task<Script> UpdateAsync(long generationId, string scriptId, string name, string sourceCode, CancellationToken ct)
+    {
+        var s = await db.Scripts.FirstOrDefaultAsync(x => x.GenerationId == generationId && x.ScriptId == scriptId, ct)
+            ?? throw new InvalidOperationException($"Script '{scriptId}' not found in generation {generationId}");
+        s.Name = name;
+        s.SourceCode = sourceCode;
+        s.SourceHash = ComputeHash(sourceCode);
+        await db.SaveChangesAsync(ct);
+        return s;
+    }
+
+    public async Task DeleteAsync(long generationId, string scriptId, CancellationToken ct)
+    {
+        var s = await db.Scripts.FirstOrDefaultAsync(x => x.GenerationId == generationId && x.ScriptId == scriptId, ct);
+        if (s is null) return;
+        db.Scripts.Remove(s);
+        await db.SaveChangesAsync(ct);
+    }
+
+    internal static string ComputeHash(string source)
+    {
+        var bytes = SHA256.HashData(Encoding.UTF8.GetBytes(source ?? string.Empty));
+        return Convert.ToHexString(bytes);
+    }
+}

src/ZB.MOM.WW.OtOpcUa.Admin/Services/ScriptTestHarnessService.cs

@@ -0,0 +1,121 @@
+using Serilog;  // resolves Serilog.ILogger explicitly in signatures
+using Serilog.Core;
+using Serilog.Events;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+using ZB.MOM.WW.OtOpcUa.Core.Scripting;
+
+namespace ZB.MOM.WW.OtOpcUa.Admin.Services;
+
+/// <summary>
+///     Dry-run harness for the Phase 7 scripting UI. Takes a script + a synthetic input
+///     map + evaluates once, returns the output (or rejection / exception) plus any
+///     logger emissions the script produced. Per Phase 7 plan decision #22: only inputs
+///     the <see cref="DependencyExtractor"/> identified can be supplied, so a dependency
+///     the harness can't prove statically surfaces as a harness error, not a runtime
+///     surprise later.
+/// </summary>
+public sealed class ScriptTestHarnessService
+{
+    /// <summary>
+    ///     Evaluate <paramref name="source"/> as a virtual-tag script (return value is the
+    ///     tag's new value). <paramref name="inputs"/> supplies synthetic
+    ///     <see cref="DataValueSnapshot"/>s for every path the extractor found.
+    /// </summary>
+    public async Task<ScriptTestResult> RunVirtualTagAsync(
+        string source, IDictionary<string, DataValueSnapshot> inputs, CancellationToken ct)
+    {
+        var deps = DependencyExtractor.Extract(source);
+        if (!deps.IsValid)
+            return ScriptTestResult.DependencyRejections(deps.Rejections);
+
+        var missing = deps.Reads.Where(r => !inputs.ContainsKey(r)).ToArray();
+        if (missing.Length > 0)
+            return ScriptTestResult.MissingInputs(missing);
+
+        var extra = inputs.Keys.Where(k => !deps.Reads.Contains(k)).ToArray();
+        if (extra.Length > 0)
+            return ScriptTestResult.UnknownInputs(extra);
+
+        ScriptEvaluator<HarnessVirtualTagContext, object?> evaluator;
+        try
+        {
+            evaluator = ScriptEvaluator<HarnessVirtualTagContext, object?>.Compile(source);
+        }
+        catch (Exception compileEx)
+        {
+            return ScriptTestResult.Threw(compileEx.Message, []);
+        }
+        var capturing = new CapturingSink();
+        var logger = new LoggerConfiguration().MinimumLevel.Verbose().WriteTo.Sink(capturing).CreateLogger();
+        var ctx = new HarnessVirtualTagContext(inputs, logger);
+
+        try
+        {
+            var result = await evaluator.RunAsync(ctx, ct);
+            return ScriptTestResult.Ok(result, ctx.Writes, capturing.Events);
+        }
+        catch (Exception ex)
+        {
+            return ScriptTestResult.Threw(ex.Message, capturing.Events);
+        }
+    }
+
+    // Public so Roslyn's script compilation can reference the context type through the
+    // ScriptGlobals<T> surface. The harness instantiates this directly; operators never see it.
+    public sealed class HarnessVirtualTagContext(
+        IDictionary<string, DataValueSnapshot> inputs, Serilog.ILogger logger) : ScriptContext
+    {
+        public Dictionary<string, object?> Writes { get; } = [];
+        public override DataValueSnapshot GetTag(string path) =>
+            inputs.TryGetValue(path, out var v)
+                ? v
+                : new DataValueSnapshot(null, Ua.StatusCodes.BadNotFound, null, DateTime.UtcNow);
+        public override void SetVirtualTag(string path, object? value) => Writes[path] = value;
+        public override DateTime Now => DateTime.UtcNow;
+        public override Serilog.ILogger Logger => logger;
+    }
+
+    private sealed class CapturingSink : ILogEventSink
+    {
+        public List<LogEvent> Events { get; } = [];
+        public void Emit(LogEvent e) => Events.Add(e);
+    }
+}
+
+/// <summary>Harness outcome: outputs, write-set, logger events, or a rejection/throw reason.</summary>
+public sealed record ScriptTestResult(
+    ScriptTestOutcome Outcome,
+    object? Output,
+    IReadOnlyDictionary<string, object?> Writes,
+    IReadOnlyList<LogEvent> LogEvents,
+    IReadOnlyList<string> Errors)
+{
+    public static ScriptTestResult Ok(object? output, IReadOnlyDictionary<string, object?> writes, IReadOnlyList<LogEvent> logs) =>
+        new(ScriptTestOutcome.Success, output, writes, logs, []);
+    public static ScriptTestResult Threw(string reason, IReadOnlyList<LogEvent> logs) =>
+        new(ScriptTestOutcome.Threw, null, new Dictionary<string, object?>(), logs, [reason]);
+    public static ScriptTestResult DependencyRejections(IReadOnlyList<DependencyRejection> rejs) =>
+        new(ScriptTestOutcome.DependencyRejected, null, new Dictionary<string, object?>(), [],
+            rejs.Select(r => r.Message).ToArray());
+    public static ScriptTestResult MissingInputs(string[] paths) =>
+        new(ScriptTestOutcome.MissingInputs, null, new Dictionary<string, object?>(), [],
+            paths.Select(p => $"Missing synthetic input: {p}").ToArray());
+    public static ScriptTestResult UnknownInputs(string[] paths) =>
+        new(ScriptTestOutcome.UnknownInputs, null, new Dictionary<string, object?>(), [],
+            paths.Select(p => $"Input '{p}' is not referenced by the script — remove it").ToArray());
+}
+
+public enum ScriptTestOutcome
+{
+    Success,
+    Threw,
+    DependencyRejected,
+    MissingInputs,
+    UnknownInputs,
+}
+
+file static class Ua
+{
+    // Mirrors OPC UA StatusCodes.BadNotFound without pulling the OPC stack into Admin.
+    public static class StatusCodes { public const uint BadNotFound = 0x803E0000; }
+}

src/ZB.MOM.WW.OtOpcUa.Admin/Services/ScriptedAlarmService.cs

@@ -0,0 +1,55 @@
+using Microsoft.EntityFrameworkCore;
+using ZB.MOM.WW.OtOpcUa.Configuration;
+using ZB.MOM.WW.OtOpcUa.Configuration.Entities;
+
+namespace ZB.MOM.WW.OtOpcUa.Admin.Services;
+
+/// <summary>Draft-generation CRUD for <see cref="ScriptedAlarm"/> rows.</summary>
+public sealed class ScriptedAlarmService(OtOpcUaConfigDbContext db)
+{
+    public Task<List<ScriptedAlarm>> ListAsync(long generationId, CancellationToken ct) =>
+        db.ScriptedAlarms.AsNoTracking()
+            .Where(a => a.GenerationId == generationId)
+            .OrderBy(a => a.EquipmentId).ThenBy(a => a.Name)
+            .ToListAsync(ct);
+
+    public async Task<ScriptedAlarm> AddAsync(
+        long generationId, string equipmentId, string name, string alarmType,
+        int severity, string messageTemplate, string predicateScriptId,
+        bool historizeToAveva, bool retain, CancellationToken ct)
+    {
+        var a = new ScriptedAlarm
+        {
+            GenerationId = generationId,
+            ScriptedAlarmId = $"sal-{Guid.NewGuid():N}"[..20],
+            EquipmentId = equipmentId,
+            Name = name,
+            AlarmType = alarmType,
+            Severity = severity,
+            MessageTemplate = messageTemplate,
+            PredicateScriptId = predicateScriptId,
+            HistorizeToAveva = historizeToAveva,
+            Retain = retain,
+        };
+        db.ScriptedAlarms.Add(a);
+        await db.SaveChangesAsync(ct);
+        return a;
+    }
+
+    public async Task DeleteAsync(long generationId, string scriptedAlarmId, CancellationToken ct)
+    {
+        var a = await db.ScriptedAlarms.FirstOrDefaultAsync(x => x.GenerationId == generationId && x.ScriptedAlarmId == scriptedAlarmId, ct);
+        if (a is null) return;
+        db.ScriptedAlarms.Remove(a);
+        await db.SaveChangesAsync(ct);
+    }
+
+    /// <summary>
+    ///     Returns the persistent state row (ack/confirm/shelve) for this alarm identity —
+    ///     alarm state is NOT generation-scoped per Phase 7 plan decision #14, so the
+    ///     lookup is by <see cref="ScriptedAlarm.ScriptedAlarmId"/> only.
+    /// </summary>
+    public Task<ScriptedAlarmState?> GetStateAsync(string scriptedAlarmId, CancellationToken ct) =>
+        db.ScriptedAlarmStates.AsNoTracking()
+            .FirstOrDefaultAsync(s => s.ScriptedAlarmId == scriptedAlarmId, ct);
+}

src/ZB.MOM.WW.OtOpcUa.Admin/Services/VirtualTagService.cs

@@ -0,0 +1,53 @@
+using Microsoft.EntityFrameworkCore;
+using ZB.MOM.WW.OtOpcUa.Configuration;
+using ZB.MOM.WW.OtOpcUa.Configuration.Entities;
+
+namespace ZB.MOM.WW.OtOpcUa.Admin.Services;
+
+/// <summary>Draft-generation CRUD for <see cref="VirtualTag"/> rows.</summary>
+public sealed class VirtualTagService(OtOpcUaConfigDbContext db)
+{
+    public Task<List<VirtualTag>> ListAsync(long generationId, CancellationToken ct) =>
+        db.VirtualTags.AsNoTracking()
+            .Where(v => v.GenerationId == generationId)
+            .OrderBy(v => v.EquipmentId).ThenBy(v => v.Name)
+            .ToListAsync(ct);
+
+    public async Task<VirtualTag> AddAsync(
+        long generationId, string equipmentId, string name, string dataType, string scriptId,
+        bool changeTriggered, int? timerIntervalMs, bool historize, CancellationToken ct)
+    {
+        var v = new VirtualTag
+        {
+            GenerationId = generationId,
+            VirtualTagId = $"vt-{Guid.NewGuid():N}"[..20],
+            EquipmentId = equipmentId,
+            Name = name,
+            DataType = dataType,
+            ScriptId = scriptId,
+            ChangeTriggered = changeTriggered,
+            TimerIntervalMs = timerIntervalMs,
+            Historize = historize,
+        };
+        db.VirtualTags.Add(v);
+        await db.SaveChangesAsync(ct);
+        return v;
+    }
+
+    public async Task DeleteAsync(long generationId, string virtualTagId, CancellationToken ct)
+    {
+        var v = await db.VirtualTags.FirstOrDefaultAsync(x => x.GenerationId == generationId && x.VirtualTagId == virtualTagId, ct);
+        if (v is null) return;
+        db.VirtualTags.Remove(v);
+        await db.SaveChangesAsync(ct);
+    }
+
+    public async Task<VirtualTag> UpdateEnabledAsync(long generationId, string virtualTagId, bool enabled, CancellationToken ct)
+    {
+        var v = await db.VirtualTags.FirstOrDefaultAsync(x => x.GenerationId == generationId && x.VirtualTagId == virtualTagId, ct)
+            ?? throw new InvalidOperationException($"VirtualTag '{virtualTagId}' not found in generation {generationId}");
+        v.Enabled = enabled;
+        await db.SaveChangesAsync(ct);
+        return v;
+    }
+}

src/ZB.MOM.WW.OtOpcUa.Admin/ZB.MOM.WW.OtOpcUa.Admin.csproj

@@ -23,6 +23,8 @@
     <ItemGroup>
         <ProjectReference Include="..\ZB.MOM.WW.OtOpcUa.Configuration\ZB.MOM.WW.OtOpcUa.Configuration.csproj"/>
         <ProjectReference Include="..\ZB.MOM.WW.OtOpcUa.Core\ZB.MOM.WW.OtOpcUa.Core.csproj"/>
+        <ProjectReference Include="..\ZB.MOM.WW.OtOpcUa.Core.Scripting\ZB.MOM.WW.OtOpcUa.Core.Scripting.csproj"/>
+        <ProjectReference Include="..\ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian\ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian.csproj"/>
     </ItemGroup>
 
     <ItemGroup>

src/ZB.MOM.WW.OtOpcUa.Admin/wwwroot/js/monaco-loader.js

@@ -0,0 +1,59 @@
+// Phase 7 Stream F — Monaco editor loader for ScriptEditor.razor.
+// Progressive enhancement: the textarea is authoritative until Monaco attaches;
+// after attach, Monaco syncs back into the textarea on every change so Blazor's
+// @bind still sees the latest value.
+
+(function () {
+    if (window.otOpcUaScriptEditor) return;
+
+    const MONACO_CDN = 'https://cdn.jsdelivr.net/npm/monaco-editor@0.52.2/min/vs';
+    let loaderPromise = null;
+
+    function ensureLoader() {
+        if (loaderPromise) return loaderPromise;
+        loaderPromise = new Promise((resolve, reject) => {
+            const script = document.createElement('script');
+            script.src = `${MONACO_CDN}/loader.js`;
+            script.onload = () => {
+                window.require.config({ paths: { vs: MONACO_CDN } });
+                window.require(['vs/editor/editor.main'], () => resolve(window.monaco));
+            };
+            script.onerror = () => reject(new Error('Monaco CDN unreachable'));
+            document.head.appendChild(script);
+        });
+        return loaderPromise;
+    }
+
+    window.otOpcUaScriptEditor = {
+        attach: async function (textareaId) {
+            const ta = document.getElementById(textareaId);
+            if (!ta) return;
+            const monaco = await ensureLoader();
+
+            // Mount Monaco over the textarea. The textarea stays in the DOM as the
+            // source of truth for Blazor's @bind — Monaco mirrors into it on every
+            // keystroke so server-side state stays in sync.
+            const host = document.createElement('div');
+            host.style.height = '340px';
+            host.style.border = '1px solid #ced4da';
+            host.style.borderRadius = '0.25rem';
+            ta.style.display = 'none';
+            ta.parentNode.insertBefore(host, ta);
+
+            const editor = monaco.editor.create(host, {
+                value: ta.value,
+                language: 'csharp',
+                theme: 'vs',
+                automaticLayout: true,
+                fontSize: 13,
+                minimap: { enabled: false },
+                scrollBeyondLastLine: false,
+            });
+
+            editor.onDidChangeModelContent(() => {
+                ta.value = editor.getValue();
+                ta.dispatchEvent(new Event('input', { bubbles: true }));
+            });
+        },
+    };
+})();

src/ZB.MOM.WW.OtOpcUa.Configuration/Entities/Script.cs

@@ -0,0 +1,38 @@
+namespace ZB.MOM.WW.OtOpcUa.Configuration.Entities;
+
+/// <summary>
+///     Per Phase 7 plan decision #8 — user-authored C# script source, referenced by
+///     <see cref="VirtualTag"/> and <see cref="ScriptedAlarm"/>. One row per script,
+///     per generation. <c>SourceHash</c> is the compile-cache key.
+/// </summary>
+/// <remarks>
+///     <para>
+///         Scripts are generation-scoped: a draft's edit creates a new row in the draft
+///         generation, the old row stays frozen in the published generation. Shape mirrors
+///         the other generation-scoped entities (Equipment, Tag, etc.) — <c>ScriptId</c> is
+///         the stable logical id that carries across generations; <c>ScriptRowId</c> is the
+///         row identity.
+///     </para>
+/// </remarks>
+public sealed class Script
+{
+    public Guid ScriptRowId { get; set; }
+    public long GenerationId { get; set; }
+
+    /// <summary>Stable logical id. Carries across generations.</summary>
+    public required string ScriptId { get; set; }
+
+    /// <summary>Operator-friendly name for log filtering + Admin UI list view.</summary>
+    public required string Name { get; set; }
+
+    /// <summary>Raw C# source. Size bounded by the DB column (nvarchar(max)).</summary>
+    public required string SourceCode { get; set; }
+
+    /// <summary>SHA-256 of <see cref="SourceCode"/> — compile-cache key for Phase 7 Stream A's <c>CompiledScriptCache</c>.</summary>
+    public required string SourceHash { get; set; }
+
+    /// <summary>Language — always "CSharp" today; placeholder for future engines (Python/Lua).</summary>
+    public string Language { get; set; } = "CSharp";
+
+    public ConfigGeneration? Generation { get; set; }
+}

src/ZB.MOM.WW.OtOpcUa.Configuration/Entities/ScriptedAlarm.cs

@@ -0,0 +1,59 @@
+namespace ZB.MOM.WW.OtOpcUa.Configuration.Entities;
+
+/// <summary>
+///     Per Phase 7 plan decisions #5, #13, #15 — a scripted OPC UA Part 9 alarm whose
+///     condition is the predicate <see cref="Script"/> referenced by
+///     <see cref="PredicateScriptId"/>. Materialized by <c>Core.ScriptedAlarms</c> as a
+///     concrete <c>AlarmConditionType</c> subtype per <see cref="AlarmType"/>.
+/// </summary>
+/// <remarks>
+///     <para>
+///         Message tokens (<c>{TagPath}</c>) resolved at emission time per plan decision #13.
+///         <see cref="HistorizeToAveva"/> (plan decision #15) gates whether transitions
+///         route through the Core.AlarmHistorian SQLite queue + Galaxy.Host to the Aveva
+///         Historian alarm schema.
+///     </para>
+/// </remarks>
+public sealed class ScriptedAlarm
+{
+    public Guid ScriptedAlarmRowId { get; set; }
+    public long GenerationId { get; set; }
+
+    /// <summary>Stable logical id — drives <c>AlarmConditionType.ConditionName</c>.</summary>
+    public required string ScriptedAlarmId { get; set; }
+
+    /// <summary>Logical FK to <see cref="Equipment.EquipmentId"/> — owner of this alarm.</summary>
+    public required string EquipmentId { get; set; }
+
+    /// <summary>Operator-facing alarm name.</summary>
+    public required string Name { get; set; }
+
+    /// <summary>Concrete Part 9 type — "AlarmCondition" / "LimitAlarm" / "OffNormalAlarm" / "DiscreteAlarm".</summary>
+    public required string AlarmType { get; set; }
+
+    /// <summary>Numeric severity 1..1000 per OPC UA Part 9 (usual bands: 1-250 Low, 251-500 Medium, 501-750 High, 751-1000 Critical).</summary>
+    public int Severity { get; set; } = 500;
+
+    /// <summary>Template with <c>{TagPath}</c> tokens resolved at emission time.</summary>
+    public required string MessageTemplate { get; set; }
+
+    /// <summary>Logical FK to <see cref="Script.ScriptId"/> — predicate script returning <c>bool</c>.</summary>
+    public required string PredicateScriptId { get; set; }
+
+    /// <summary>
+    ///     Plan decision #15 — when true, transitions route through the SQLite store-and-forward
+    ///     queue to the Aveva Historian. Defaults on for scripted alarms because they are the
+    ///     primary motivation for the historian sink; operator can disable per alarm.
+    /// </summary>
+    public bool HistorizeToAveva { get; set; } = true;
+
+    /// <summary>
+    ///     OPC UA Part 9 <c>Retain</c> flag — whether the alarm keeps active-state between
+    ///     sessions. Most plant alarms are retained; one-shot event-style alarms are not.
+    /// </summary>
+    public bool Retain { get; set; } = true;
+
+    public bool Enabled { get; set; } = true;
+
+    public ConfigGeneration? Generation { get; set; }
+}

src/ZB.MOM.WW.OtOpcUa.Configuration/Entities/ScriptedAlarmState.cs

@@ -0,0 +1,62 @@
+namespace ZB.MOM.WW.OtOpcUa.Configuration.Entities;
+
+/// <summary>
+///     Per Phase 7 plan decision #14 — persistent runtime state for each scripted alarm.
+///     Survives process restart so operators don't re-ack and ack history survives for
+///     GxP / 21 CFR Part 11 compliance. Keyed on <c>ScriptedAlarmId</c> logically (not
+///     per-generation) because ack state follows the alarm's stable identity across
+///     generations — a Modified alarm keeps its ack history.
+/// </summary>
+/// <remarks>
+///     <para>
+///         <c>ActiveState</c> is deliberately NOT persisted — it rederives from the current
+///         predicate evaluation on startup. Only operator-supplied state (<see cref="AckedState"/>,
+///         <see cref="ConfirmedState"/>, <see cref="ShelvingState"/>) + audit trail persist.
+///     </para>
+///     <para>
+///         <see cref="CommentsJson"/> is an append-only JSON array of <c>{user, utc, text}</c>
+///         tuples — one per operator comment. Core.ScriptedAlarms' <c>AlarmConditionState.Comments</c>
+///         serializes directly into this column.
+///     </para>
+/// </remarks>
+public sealed class ScriptedAlarmState
+{
+    /// <summary>Logical FK — matches <see cref="ScriptedAlarm.ScriptedAlarmId"/>. One row per alarm identity.</summary>
+    public required string ScriptedAlarmId { get; set; }
+
+    /// <summary>Enabled/Disabled. Persists across restart per plan decision #14.</summary>
+    public required string EnabledState { get; set; } = "Enabled";
+
+    /// <summary>Unacknowledged / Acknowledged.</summary>
+    public required string AckedState { get; set; } = "Unacknowledged";
+
+    /// <summary>Unconfirmed / Confirmed.</summary>
+    public required string ConfirmedState { get; set; } = "Unconfirmed";
+
+    /// <summary>Unshelved / OneShotShelved / TimedShelved.</summary>
+    public required string ShelvingState { get; set; } = "Unshelved";
+
+    /// <summary>When a TimedShelve expires — null if not shelved or OneShotShelved.</summary>
+    public DateTime? ShelvingExpiresUtc { get; set; }
+
+    /// <summary>User who last acknowledged. Null if never acked.</summary>
+    public string? LastAckUser { get; set; }
+
+    /// <summary>Operator-supplied ack comment. Null if no comment or never acked.</summary>
+    public string? LastAckComment { get; set; }
+
+    public DateTime? LastAckUtc { get; set; }
+
+    /// <summary>User who last confirmed.</summary>
+    public string? LastConfirmUser { get; set; }
+
+    public string? LastConfirmComment { get; set; }
+
+    public DateTime? LastConfirmUtc { get; set; }
+
+    /// <summary>JSON array of operator comments, append-only (GxP audit).</summary>
+    public string CommentsJson { get; set; } = "[]";
+
+    /// <summary>Row write timestamp — tracks last state change.</summary>
+    public DateTime UpdatedAtUtc { get; set; }
+}

src/ZB.MOM.WW.OtOpcUa.Configuration/Entities/VirtualTag.cs

@@ -0,0 +1,53 @@
+namespace ZB.MOM.WW.OtOpcUa.Configuration.Entities;
+
+/// <summary>
+///     Per Phase 7 plan decision #2 — a virtual (calculated) tag that lives in the
+///     Equipment tree alongside driver tags. Value is produced by the
+///     <see cref="Script"/> referenced by <see cref="ScriptId"/>.
+/// </summary>
+/// <remarks>
+///     <para>
+///         <see cref="EquipmentId"/> is mandatory — virtual tags are always scoped to an
+///         Equipment node per plan decision #2 (unified Equipment tree, not a separate
+///         /Virtual namespace). <see cref="DataType"/> matches the shape used by
+///         <c>Tag.DataType</c>.
+///     </para>
+///     <para>
+///         <see cref="ChangeTriggered"/> and <see cref="TimerIntervalMs"/> together realize
+///         plan decision #3 (change + timer). At least one must produce evaluations; the
+///         Core.VirtualTags engine rejects an all-disabled tag at load time.
+///     </para>
+/// </remarks>
+public sealed class VirtualTag
+{
+    public Guid VirtualTagRowId { get; set; }
+    public long GenerationId { get; set; }
+
+    /// <summary>Stable logical id.</summary>
+    public required string VirtualTagId { get; set; }
+
+    /// <summary>Logical FK to <see cref="Equipment.EquipmentId"/> — owner of this virtual tag.</summary>
+    public required string EquipmentId { get; set; }
+
+    /// <summary>Browse name — unique within owning Equipment.</summary>
+    public required string Name { get; set; }
+
+    /// <summary>DataType string — same vocabulary as <see cref="Tag.DataType"/>.</summary>
+    public required string DataType { get; set; }
+
+    /// <summary>Logical FK to <see cref="Script.ScriptId"/> — the script that computes this tag's value.</summary>
+    public required string ScriptId { get; set; }
+
+    /// <summary>Re-evaluate when any referenced input tag changes. Default on.</summary>
+    public bool ChangeTriggered { get; set; } = true;
+
+    /// <summary>Timer re-evaluation cadence in milliseconds. <c>null</c> = no timer.</summary>
+    public int? TimerIntervalMs { get; set; }
+
+    /// <summary>Per plan decision #10 — checkbox to route this tag's values through <c>IHistoryWriter</c>.</summary>
+    public bool Historize { get; set; }
+
+    public bool Enabled { get; set; } = true;
+
+    public ConfigGeneration? Generation { get; set; }
+}

src/ZB.MOM.WW.OtOpcUa.Configuration/Migrations/20260420231641_AddPhase7ScriptingTables.cs

@@ -0,0 +1,186 @@
+using System;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace ZB.MOM.WW.OtOpcUa.Configuration.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddPhase7ScriptingTables : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateTable(
+                name: "Script",
+                columns: table => new
+                {
+                    ScriptRowId = table.Column<Guid>(type: "uniqueidentifier", nullable: false, defaultValueSql: "NEWSEQUENTIALID()"),
+                    GenerationId = table.Column<long>(type: "bigint", nullable: false),
+                    ScriptId = table.Column<string>(type: "nvarchar(64)", maxLength: 64, nullable: true),
+                    Name = table.Column<string>(type: "nvarchar(128)", maxLength: 128, nullable: false),
+                    SourceCode = table.Column<string>(type: "nvarchar(max)", nullable: false),
+                    SourceHash = table.Column<string>(type: "nvarchar(64)", maxLength: 64, nullable: false),
+                    Language = table.Column<string>(type: "nvarchar(16)", maxLength: 16, nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_Script", x => x.ScriptRowId);
+                    table.ForeignKey(
+                        name: "FK_Script_ConfigGeneration_GenerationId",
+                        column: x => x.GenerationId,
+                        principalTable: "ConfigGeneration",
+                        principalColumn: "GenerationId",
+                        onDelete: ReferentialAction.Restrict);
+                });
+
+            migrationBuilder.CreateTable(
+                name: "ScriptedAlarm",
+                columns: table => new
+                {
+                    ScriptedAlarmRowId = table.Column<Guid>(type: "uniqueidentifier", nullable: false, defaultValueSql: "NEWSEQUENTIALID()"),
+                    GenerationId = table.Column<long>(type: "bigint", nullable: false),
+                    ScriptedAlarmId = table.Column<string>(type: "nvarchar(64)", maxLength: 64, nullable: true),
+                    EquipmentId = table.Column<string>(type: "nvarchar(64)", maxLength: 64, nullable: false),
+                    Name = table.Column<string>(type: "nvarchar(128)", maxLength: 128, nullable: false),
+                    AlarmType = table.Column<string>(type: "nvarchar(32)", maxLength: 32, nullable: false),
+                    Severity = table.Column<int>(type: "int", nullable: false),
+                    MessageTemplate = table.Column<string>(type: "nvarchar(1024)", maxLength: 1024, nullable: false),
+                    PredicateScriptId = table.Column<string>(type: "nvarchar(64)", maxLength: 64, nullable: false),
+                    HistorizeToAveva = table.Column<bool>(type: "bit", nullable: false),
+                    Retain = table.Column<bool>(type: "bit", nullable: false),
+                    Enabled = table.Column<bool>(type: "bit", nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_ScriptedAlarm", x => x.ScriptedAlarmRowId);
+                    table.CheckConstraint("CK_ScriptedAlarm_AlarmType", "AlarmType IN ('AlarmCondition','LimitAlarm','OffNormalAlarm','DiscreteAlarm')");
+                    table.CheckConstraint("CK_ScriptedAlarm_Severity_Range", "Severity BETWEEN 1 AND 1000");
+                    table.ForeignKey(
+                        name: "FK_ScriptedAlarm_ConfigGeneration_GenerationId",
+                        column: x => x.GenerationId,
+                        principalTable: "ConfigGeneration",
+                        principalColumn: "GenerationId",
+                        onDelete: ReferentialAction.Restrict);
+                });
+
+            migrationBuilder.CreateTable(
+                name: "ScriptedAlarmState",
+                columns: table => new
+                {
+                    ScriptedAlarmId = table.Column<string>(type: "nvarchar(64)", maxLength: 64, nullable: false),
+                    EnabledState = table.Column<string>(type: "nvarchar(16)", maxLength: 16, nullable: false),
+                    AckedState = table.Column<string>(type: "nvarchar(16)", maxLength: 16, nullable: false),
+                    ConfirmedState = table.Column<string>(type: "nvarchar(16)", maxLength: 16, nullable: false),
+                    ShelvingState = table.Column<string>(type: "nvarchar(16)", maxLength: 16, nullable: false),
+                    ShelvingExpiresUtc = table.Column<DateTime>(type: "datetime2(3)", nullable: true),
+                    LastAckUser = table.Column<string>(type: "nvarchar(128)", maxLength: 128, nullable: true),
+                    LastAckComment = table.Column<string>(type: "nvarchar(1024)", maxLength: 1024, nullable: true),
+                    LastAckUtc = table.Column<DateTime>(type: "datetime2(3)", nullable: true),
+                    LastConfirmUser = table.Column<string>(type: "nvarchar(128)", maxLength: 128, nullable: true),
+                    LastConfirmComment = table.Column<string>(type: "nvarchar(1024)", maxLength: 1024, nullable: true),
+                    LastConfirmUtc = table.Column<DateTime>(type: "datetime2(3)", nullable: true),
+                    CommentsJson = table.Column<string>(type: "nvarchar(max)", nullable: false),
+                    UpdatedAtUtc = table.Column<DateTime>(type: "datetime2(3)", nullable: false, defaultValueSql: "SYSUTCDATETIME()")
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_ScriptedAlarmState", x => x.ScriptedAlarmId);
+                    table.CheckConstraint("CK_ScriptedAlarmState_CommentsJson_IsJson", "ISJSON(CommentsJson) = 1");
+                });
+
+            migrationBuilder.CreateTable(
+                name: "VirtualTag",
+                columns: table => new
+                {
+                    VirtualTagRowId = table.Column<Guid>(type: "uniqueidentifier", nullable: false, defaultValueSql: "NEWSEQUENTIALID()"),
+                    GenerationId = table.Column<long>(type: "bigint", nullable: false),
+                    VirtualTagId = table.Column<string>(type: "nvarchar(64)", maxLength: 64, nullable: true),
+                    EquipmentId = table.Column<string>(type: "nvarchar(64)", maxLength: 64, nullable: false),
+                    Name = table.Column<string>(type: "nvarchar(128)", maxLength: 128, nullable: false),
+                    DataType = table.Column<string>(type: "nvarchar(32)", maxLength: 32, nullable: false),
+                    ScriptId = table.Column<string>(type: "nvarchar(64)", maxLength: 64, nullable: false),
+                    ChangeTriggered = table.Column<bool>(type: "bit", nullable: false),
+                    TimerIntervalMs = table.Column<int>(type: "int", nullable: true),
+                    Historize = table.Column<bool>(type: "bit", nullable: false),
+                    Enabled = table.Column<bool>(type: "bit", nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_VirtualTag", x => x.VirtualTagRowId);
+                    table.CheckConstraint("CK_VirtualTag_TimerInterval_Min", "TimerIntervalMs IS NULL OR TimerIntervalMs >= 50");
+                    table.CheckConstraint("CK_VirtualTag_Trigger_AtLeastOne", "ChangeTriggered = 1 OR TimerIntervalMs IS NOT NULL");
+                    table.ForeignKey(
+                        name: "FK_VirtualTag_ConfigGeneration_GenerationId",
+                        column: x => x.GenerationId,
+                        principalTable: "ConfigGeneration",
+                        principalColumn: "GenerationId",
+                        onDelete: ReferentialAction.Restrict);
+                });
+
+            migrationBuilder.CreateIndex(
+                name: "IX_Script_Generation_SourceHash",
+                table: "Script",
+                columns: new[] { "GenerationId", "SourceHash" });
+
+            migrationBuilder.CreateIndex(
+                name: "UX_Script_Generation_LogicalId",
+                table: "Script",
+                columns: new[] { "GenerationId", "ScriptId" },
+                unique: true,
+                filter: "[ScriptId] IS NOT NULL");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_ScriptedAlarm_Generation_Script",
+                table: "ScriptedAlarm",
+                columns: new[] { "GenerationId", "PredicateScriptId" });
+
+            migrationBuilder.CreateIndex(
+                name: "UX_ScriptedAlarm_Generation_EquipmentPath",
+                table: "ScriptedAlarm",
+                columns: new[] { "GenerationId", "EquipmentId", "Name" },
+                unique: true);
+
+            migrationBuilder.CreateIndex(
+                name: "UX_ScriptedAlarm_Generation_LogicalId",
+                table: "ScriptedAlarm",
+                columns: new[] { "GenerationId", "ScriptedAlarmId" },
+                unique: true,
+                filter: "[ScriptedAlarmId] IS NOT NULL");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_VirtualTag_Generation_Script",
+                table: "VirtualTag",
+                columns: new[] { "GenerationId", "ScriptId" });
+
+            migrationBuilder.CreateIndex(
+                name: "UX_VirtualTag_Generation_EquipmentPath",
+                table: "VirtualTag",
+                columns: new[] { "GenerationId", "EquipmentId", "Name" },
+                unique: true);
+
+            migrationBuilder.CreateIndex(
+                name: "UX_VirtualTag_Generation_LogicalId",
+                table: "VirtualTag",
+                columns: new[] { "GenerationId", "VirtualTagId" },
+                unique: true,
+                filter: "[VirtualTagId] IS NOT NULL");
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropTable(
+                name: "Script");
+
+            migrationBuilder.DropTable(
+                name: "ScriptedAlarm");
+
+            migrationBuilder.DropTable(
+                name: "ScriptedAlarmState");
+
+            migrationBuilder.DropTable(
+                name: "VirtualTag");
+        }
+    }
+}

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

@@ -1027,6 +1027,193 @@ namespace ZB.MOM.WW.OtOpcUa.Configuration.Migrations
                         });
                 });
 
+            modelBuilder.Entity("ZB.MOM.WW.OtOpcUa.Configuration.Entities.Script", b =>
+                {
+                    b.Property<Guid>("ScriptRowId")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("uniqueidentifier")
+                        .HasDefaultValueSql("NEWSEQUENTIALID()");
+
+                    b.Property<long>("GenerationId")
+                        .HasColumnType("bigint");
+
+                    b.Property<string>("Language")
+                        .IsRequired()
+                        .HasMaxLength(16)
+                        .HasColumnType("nvarchar(16)");
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .HasMaxLength(128)
+                        .HasColumnType("nvarchar(128)");
+
+                    b.Property<string>("ScriptId")
+                        .HasMaxLength(64)
+                        .HasColumnType("nvarchar(64)");
+
+                    b.Property<string>("SourceCode")
+                        .IsRequired()
+                        .HasColumnType("nvarchar(max)");
+
+                    b.Property<string>("SourceHash")
+                        .IsRequired()
+                        .HasMaxLength(64)
+                        .HasColumnType("nvarchar(64)");
+
+                    b.HasKey("ScriptRowId");
+
+                    b.HasIndex("GenerationId", "ScriptId")
+                        .IsUnique()
+                        .HasDatabaseName("UX_Script_Generation_LogicalId")
+                        .HasFilter("[ScriptId] IS NOT NULL");
+
+                    b.HasIndex("GenerationId", "SourceHash")
+                        .HasDatabaseName("IX_Script_Generation_SourceHash");
+
+                    b.ToTable("Script", (string)null);
+                });
+
+            modelBuilder.Entity("ZB.MOM.WW.OtOpcUa.Configuration.Entities.ScriptedAlarm", b =>
+                {
+                    b.Property<Guid>("ScriptedAlarmRowId")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("uniqueidentifier")
+                        .HasDefaultValueSql("NEWSEQUENTIALID()");
+
+                    b.Property<string>("AlarmType")
+                        .IsRequired()
+                        .HasMaxLength(32)
+                        .HasColumnType("nvarchar(32)");
+
+                    b.Property<bool>("Enabled")
+                        .HasColumnType("bit");
+
+                    b.Property<string>("EquipmentId")
+                        .IsRequired()
+                        .HasMaxLength(64)
+                        .HasColumnType("nvarchar(64)");
+
+                    b.Property<long>("GenerationId")
+                        .HasColumnType("bigint");
+
+                    b.Property<bool>("HistorizeToAveva")
+                        .HasColumnType("bit");
+
+                    b.Property<string>("MessageTemplate")
+                        .IsRequired()
+                        .HasMaxLength(1024)
+                        .HasColumnType("nvarchar(1024)");
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .HasMaxLength(128)
+                        .HasColumnType("nvarchar(128)");
+
+                    b.Property<string>("PredicateScriptId")
+                        .IsRequired()
+                        .HasMaxLength(64)
+                        .HasColumnType("nvarchar(64)");
+
+                    b.Property<bool>("Retain")
+                        .HasColumnType("bit");
+
+                    b.Property<string>("ScriptedAlarmId")
+                        .HasMaxLength(64)
+                        .HasColumnType("nvarchar(64)");
+
+                    b.Property<int>("Severity")
+                        .HasColumnType("int");
+
+                    b.HasKey("ScriptedAlarmRowId");
+
+                    b.HasIndex("GenerationId", "PredicateScriptId")
+                        .HasDatabaseName("IX_ScriptedAlarm_Generation_Script");
+
+                    b.HasIndex("GenerationId", "ScriptedAlarmId")
+                        .IsUnique()
+                        .HasDatabaseName("UX_ScriptedAlarm_Generation_LogicalId")
+                        .HasFilter("[ScriptedAlarmId] IS NOT NULL");
+
+                    b.HasIndex("GenerationId", "EquipmentId", "Name")
+                        .IsUnique()
+                        .HasDatabaseName("UX_ScriptedAlarm_Generation_EquipmentPath");
+
+                    b.ToTable("ScriptedAlarm", null, t =>
+                        {
+                            t.HasCheckConstraint("CK_ScriptedAlarm_AlarmType", "AlarmType IN ('AlarmCondition','LimitAlarm','OffNormalAlarm','DiscreteAlarm')");
+
+                            t.HasCheckConstraint("CK_ScriptedAlarm_Severity_Range", "Severity BETWEEN 1 AND 1000");
+                        });
+                });
+
+            modelBuilder.Entity("ZB.MOM.WW.OtOpcUa.Configuration.Entities.ScriptedAlarmState", b =>
+                {
+                    b.Property<string>("ScriptedAlarmId")
+                        .HasMaxLength(64)
+                        .HasColumnType("nvarchar(64)");
+
+                    b.Property<string>("AckedState")
+                        .IsRequired()
+                        .HasMaxLength(16)
+                        .HasColumnType("nvarchar(16)");
+
+                    b.Property<string>("CommentsJson")
+                        .IsRequired()
+                        .HasColumnType("nvarchar(max)");
+
+                    b.Property<string>("ConfirmedState")
+                        .IsRequired()
+                        .HasMaxLength(16)
+                        .HasColumnType("nvarchar(16)");
+
+                    b.Property<string>("EnabledState")
+                        .IsRequired()
+                        .HasMaxLength(16)
+                        .HasColumnType("nvarchar(16)");
+
+                    b.Property<string>("LastAckComment")
+                        .HasMaxLength(1024)
+                        .HasColumnType("nvarchar(1024)");
+
+                    b.Property<string>("LastAckUser")
+                        .HasMaxLength(128)
+                        .HasColumnType("nvarchar(128)");
+
+                    b.Property<DateTime?>("LastAckUtc")
+                        .HasColumnType("datetime2(3)");
+
+                    b.Property<string>("LastConfirmComment")
+                        .HasMaxLength(1024)
+                        .HasColumnType("nvarchar(1024)");
+
+                    b.Property<string>("LastConfirmUser")
+                        .HasMaxLength(128)
+                        .HasColumnType("nvarchar(128)");
+
+                    b.Property<DateTime?>("LastConfirmUtc")
+                        .HasColumnType("datetime2(3)");
+
+                    b.Property<DateTime?>("ShelvingExpiresUtc")
+                        .HasColumnType("datetime2(3)");
+
+                    b.Property<string>("ShelvingState")
+                        .IsRequired()
+                        .HasMaxLength(16)
+                        .HasColumnType("nvarchar(16)");
+
+                    b.Property<DateTime>("UpdatedAtUtc")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("datetime2(3)")
+                        .HasDefaultValueSql("SYSUTCDATETIME()");
+
+                    b.HasKey("ScriptedAlarmId");
+
+                    b.ToTable("ScriptedAlarmState", null, t =>
+                        {
+                            t.HasCheckConstraint("CK_ScriptedAlarmState_CommentsJson_IsJson", "ISJSON(CommentsJson) = 1");
+                        });
+                });
+
             modelBuilder.Entity("ZB.MOM.WW.OtOpcUa.Configuration.Entities.ServerCluster", b =>
                 {
                     b.Property<string>("ClusterId")
@@ -1274,6 +1461,74 @@ namespace ZB.MOM.WW.OtOpcUa.Configuration.Migrations
                     b.ToTable("UnsLine", (string)null);
                 });
 
+            modelBuilder.Entity("ZB.MOM.WW.OtOpcUa.Configuration.Entities.VirtualTag", b =>
+                {
+                    b.Property<Guid>("VirtualTagRowId")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("uniqueidentifier")
+                        .HasDefaultValueSql("NEWSEQUENTIALID()");
+
+                    b.Property<bool>("ChangeTriggered")
+                        .HasColumnType("bit");
+
+                    b.Property<string>("DataType")
+                        .IsRequired()
+                        .HasMaxLength(32)
+                        .HasColumnType("nvarchar(32)");
+
+                    b.Property<bool>("Enabled")
+                        .HasColumnType("bit");
+
+                    b.Property<string>("EquipmentId")
+                        .IsRequired()
+                        .HasMaxLength(64)
+                        .HasColumnType("nvarchar(64)");
+
+                    b.Property<long>("GenerationId")
+                        .HasColumnType("bigint");
+
+                    b.Property<bool>("Historize")
+                        .HasColumnType("bit");
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .HasMaxLength(128)
+                        .HasColumnType("nvarchar(128)");
+
+                    b.Property<string>("ScriptId")
+                        .IsRequired()
+                        .HasMaxLength(64)
+                        .HasColumnType("nvarchar(64)");
+
+                    b.Property<int?>("TimerIntervalMs")
+                        .HasColumnType("int");
+
+                    b.Property<string>("VirtualTagId")
+                        .HasMaxLength(64)
+                        .HasColumnType("nvarchar(64)");
+
+                    b.HasKey("VirtualTagRowId");
+
+                    b.HasIndex("GenerationId", "ScriptId")
+                        .HasDatabaseName("IX_VirtualTag_Generation_Script");
+
+                    b.HasIndex("GenerationId", "VirtualTagId")
+                        .IsUnique()
+                        .HasDatabaseName("UX_VirtualTag_Generation_LogicalId")
+                        .HasFilter("[VirtualTagId] IS NOT NULL");
+
+                    b.HasIndex("GenerationId", "EquipmentId", "Name")
+                        .IsUnique()
+                        .HasDatabaseName("UX_VirtualTag_Generation_EquipmentPath");
+
+                    b.ToTable("VirtualTag", null, t =>
+                        {
+                            t.HasCheckConstraint("CK_VirtualTag_TimerInterval_Min", "TimerIntervalMs IS NULL OR TimerIntervalMs >= 50");
+
+                            t.HasCheckConstraint("CK_VirtualTag_Trigger_AtLeastOne", "ChangeTriggered = 1 OR TimerIntervalMs IS NOT NULL");
+                        });
+                });
+
             modelBuilder.Entity("ZB.MOM.WW.OtOpcUa.Configuration.Entities.ClusterNode", b =>
                 {
                     b.HasOne("ZB.MOM.WW.OtOpcUa.Configuration.Entities.ServerCluster", "Cluster")
@@ -1435,6 +1690,28 @@ namespace ZB.MOM.WW.OtOpcUa.Configuration.Migrations
                     b.Navigation("Generation");
                 });
 
+            modelBuilder.Entity("ZB.MOM.WW.OtOpcUa.Configuration.Entities.Script", b =>
+                {
+                    b.HasOne("ZB.MOM.WW.OtOpcUa.Configuration.Entities.ConfigGeneration", "Generation")
+                        .WithMany()
+                        .HasForeignKey("GenerationId")
+                        .OnDelete(DeleteBehavior.Restrict)
+                        .IsRequired();
+
+                    b.Navigation("Generation");
+                });
+
+            modelBuilder.Entity("ZB.MOM.WW.OtOpcUa.Configuration.Entities.ScriptedAlarm", b =>
+                {
+                    b.HasOne("ZB.MOM.WW.OtOpcUa.Configuration.Entities.ConfigGeneration", "Generation")
+                        .WithMany()
+                        .HasForeignKey("GenerationId")
+                        .OnDelete(DeleteBehavior.Restrict)
+                        .IsRequired();
+
+                    b.Navigation("Generation");
+                });
+
             modelBuilder.Entity("ZB.MOM.WW.OtOpcUa.Configuration.Entities.Tag", b =>
                 {
                     b.HasOne("ZB.MOM.WW.OtOpcUa.Configuration.Entities.ConfigGeneration", "Generation")
@@ -1476,6 +1753,17 @@ namespace ZB.MOM.WW.OtOpcUa.Configuration.Migrations
                     b.Navigation("Generation");
                 });
 
+            modelBuilder.Entity("ZB.MOM.WW.OtOpcUa.Configuration.Entities.VirtualTag", b =>
+                {
+                    b.HasOne("ZB.MOM.WW.OtOpcUa.Configuration.Entities.ConfigGeneration", "Generation")
+                        .WithMany()
+                        .HasForeignKey("GenerationId")
+                        .OnDelete(DeleteBehavior.Restrict)
+                        .IsRequired();
+
+                    b.Navigation("Generation");
+                });
+
             modelBuilder.Entity("ZB.MOM.WW.OtOpcUa.Configuration.Entities.ClusterNode", b =>
                 {
                     b.Navigation("Credentials");

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

@@ -32,6 +32,10 @@ public sealed class OtOpcUaConfigDbContext(DbContextOptions<OtOpcUaConfigDbConte
     public DbSet<LdapGroupRoleMapping> LdapGroupRoleMappings => Set<LdapGroupRoleMapping>();
     public DbSet<EquipmentImportBatch> EquipmentImportBatches => Set<EquipmentImportBatch>();
     public DbSet<EquipmentImportRow> EquipmentImportRows => Set<EquipmentImportRow>();
+    public DbSet<Script> Scripts => Set<Script>();
+    public DbSet<VirtualTag> VirtualTags => Set<VirtualTag>();
+    public DbSet<ScriptedAlarm> ScriptedAlarms => Set<ScriptedAlarm>();
+    public DbSet<ScriptedAlarmState> ScriptedAlarmStates => Set<ScriptedAlarmState>();
 
     protected override void OnModelCreating(ModelBuilder modelBuilder)
     {
@@ -56,6 +60,10 @@ public sealed class OtOpcUaConfigDbContext(DbContextOptions<OtOpcUaConfigDbConte
         ConfigureDriverInstanceResilienceStatus(modelBuilder);
         ConfigureLdapGroupRoleMapping(modelBuilder);
         ConfigureEquipmentImportBatch(modelBuilder);
+        ConfigureScript(modelBuilder);
+        ConfigureVirtualTag(modelBuilder);
+        ConfigureScriptedAlarm(modelBuilder);
+        ConfigureScriptedAlarmState(modelBuilder);
     }
 
     private static void ConfigureServerCluster(ModelBuilder modelBuilder)
@@ -619,4 +627,106 @@ public sealed class OtOpcUaConfigDbContext(DbContextOptions<OtOpcUaConfigDbConte
             e.HasIndex(x => x.BatchId).HasDatabaseName("IX_EquipmentImportRow_Batch");
         });
     }
+
+    private static void ConfigureScript(ModelBuilder modelBuilder)
+    {
+        modelBuilder.Entity<Script>(e =>
+        {
+            e.ToTable("Script");
+            e.HasKey(x => x.ScriptRowId);
+            e.Property(x => x.ScriptRowId).HasDefaultValueSql("NEWSEQUENTIALID()");
+            e.Property(x => x.ScriptId).HasMaxLength(64);
+            e.Property(x => x.Name).HasMaxLength(128);
+            e.Property(x => x.SourceCode).HasColumnType("nvarchar(max)");
+            e.Property(x => x.SourceHash).HasMaxLength(64);
+            e.Property(x => x.Language).HasMaxLength(16);
+
+            e.HasOne(x => x.Generation).WithMany().HasForeignKey(x => x.GenerationId).OnDelete(DeleteBehavior.Restrict);
+
+            e.HasIndex(x => new { x.GenerationId, x.ScriptId }).IsUnique().HasDatabaseName("UX_Script_Generation_LogicalId");
+            e.HasIndex(x => new { x.GenerationId, x.SourceHash }).HasDatabaseName("IX_Script_Generation_SourceHash");
+        });
+    }
+
+    private static void ConfigureVirtualTag(ModelBuilder modelBuilder)
+    {
+        modelBuilder.Entity<VirtualTag>(e =>
+        {
+            e.ToTable("VirtualTag", t =>
+            {
+                t.HasCheckConstraint("CK_VirtualTag_Trigger_AtLeastOne",
+                    "ChangeTriggered = 1 OR TimerIntervalMs IS NOT NULL");
+                t.HasCheckConstraint("CK_VirtualTag_TimerInterval_Min",
+                    "TimerIntervalMs IS NULL OR TimerIntervalMs >= 50");
+            });
+            e.HasKey(x => x.VirtualTagRowId);
+            e.Property(x => x.VirtualTagRowId).HasDefaultValueSql("NEWSEQUENTIALID()");
+            e.Property(x => x.VirtualTagId).HasMaxLength(64);
+            e.Property(x => x.EquipmentId).HasMaxLength(64);
+            e.Property(x => x.Name).HasMaxLength(128);
+            e.Property(x => x.DataType).HasMaxLength(32);
+            e.Property(x => x.ScriptId).HasMaxLength(64);
+
+            e.HasOne(x => x.Generation).WithMany().HasForeignKey(x => x.GenerationId).OnDelete(DeleteBehavior.Restrict);
+
+            e.HasIndex(x => new { x.GenerationId, x.VirtualTagId }).IsUnique().HasDatabaseName("UX_VirtualTag_Generation_LogicalId");
+            e.HasIndex(x => new { x.GenerationId, x.EquipmentId, x.Name }).IsUnique().HasDatabaseName("UX_VirtualTag_Generation_EquipmentPath");
+            e.HasIndex(x => new { x.GenerationId, x.ScriptId }).HasDatabaseName("IX_VirtualTag_Generation_Script");
+        });
+    }
+
+    private static void ConfigureScriptedAlarm(ModelBuilder modelBuilder)
+    {
+        modelBuilder.Entity<ScriptedAlarm>(e =>
+        {
+            e.ToTable("ScriptedAlarm", t =>
+            {
+                t.HasCheckConstraint("CK_ScriptedAlarm_Severity_Range", "Severity BETWEEN 1 AND 1000");
+                t.HasCheckConstraint("CK_ScriptedAlarm_AlarmType",
+                    "AlarmType IN ('AlarmCondition','LimitAlarm','OffNormalAlarm','DiscreteAlarm')");
+            });
+            e.HasKey(x => x.ScriptedAlarmRowId);
+            e.Property(x => x.ScriptedAlarmRowId).HasDefaultValueSql("NEWSEQUENTIALID()");
+            e.Property(x => x.ScriptedAlarmId).HasMaxLength(64);
+            e.Property(x => x.EquipmentId).HasMaxLength(64);
+            e.Property(x => x.Name).HasMaxLength(128);
+            e.Property(x => x.AlarmType).HasMaxLength(32);
+            e.Property(x => x.MessageTemplate).HasMaxLength(1024);
+            e.Property(x => x.PredicateScriptId).HasMaxLength(64);
+
+            e.HasOne(x => x.Generation).WithMany().HasForeignKey(x => x.GenerationId).OnDelete(DeleteBehavior.Restrict);
+
+            e.HasIndex(x => new { x.GenerationId, x.ScriptedAlarmId }).IsUnique().HasDatabaseName("UX_ScriptedAlarm_Generation_LogicalId");
+            e.HasIndex(x => new { x.GenerationId, x.EquipmentId, x.Name }).IsUnique().HasDatabaseName("UX_ScriptedAlarm_Generation_EquipmentPath");
+            e.HasIndex(x => new { x.GenerationId, x.PredicateScriptId }).HasDatabaseName("IX_ScriptedAlarm_Generation_Script");
+        });
+    }
+
+    private static void ConfigureScriptedAlarmState(ModelBuilder modelBuilder)
+    {
+        modelBuilder.Entity<ScriptedAlarmState>(e =>
+        {
+            // Logical-id keyed (not generation-scoped) because ack state follows the alarm's
+            // stable identity across generations — Modified alarms keep their ack audit trail.
+            e.ToTable("ScriptedAlarmState", t =>
+            {
+                t.HasCheckConstraint("CK_ScriptedAlarmState_CommentsJson_IsJson", "ISJSON(CommentsJson) = 1");
+            });
+            e.HasKey(x => x.ScriptedAlarmId);
+            e.Property(x => x.ScriptedAlarmId).HasMaxLength(64);
+            e.Property(x => x.EnabledState).HasMaxLength(16);
+            e.Property(x => x.AckedState).HasMaxLength(16);
+            e.Property(x => x.ConfirmedState).HasMaxLength(16);
+            e.Property(x => x.ShelvingState).HasMaxLength(16);
+            e.Property(x => x.ShelvingExpiresUtc).HasColumnType("datetime2(3)");
+            e.Property(x => x.LastAckUser).HasMaxLength(128);
+            e.Property(x => x.LastAckComment).HasMaxLength(1024);
+            e.Property(x => x.LastAckUtc).HasColumnType("datetime2(3)");
+            e.Property(x => x.LastConfirmUser).HasMaxLength(128);
+            e.Property(x => x.LastConfirmComment).HasMaxLength(1024);
+            e.Property(x => x.LastConfirmUtc).HasColumnType("datetime2(3)");
+            e.Property(x => x.CommentsJson).HasColumnType("nvarchar(max)");
+            e.Property(x => x.UpdatedAtUtc).HasColumnType("datetime2(3)").HasDefaultValueSql("SYSUTCDATETIME()");
+        });
+    }
 }

src/ZB.MOM.WW.OtOpcUa.Core.Abstractions/DriverAttributeInfo.cs

@@ -33,6 +33,18 @@ namespace ZB.MOM.WW.OtOpcUa.Core.Abstractions;
 ///     (holding registers with level-set values, set-point writes to analog tags) — the
 ///     capability invoker respects this flag when deciding whether to apply Polly retry.
 /// </param>
+/// <param name="Source">
+///     Per ADR-002 — discriminates which runtime subsystem owns this node's dispatch.
+///     Defaults to <see cref="NodeSourceKind.Driver"/> so existing callers are unchanged.
+/// </param>
+/// <param name="VirtualTagId">
+///     Set when <paramref name="Source"/> is <see cref="NodeSourceKind.Virtual"/> — stable
+///     logical id the VirtualTagEngine addresses by. Null otherwise.
+/// </param>
+/// <param name="ScriptedAlarmId">
+///     Set when <paramref name="Source"/> is <see cref="NodeSourceKind.ScriptedAlarm"/> —
+///     stable logical id the ScriptedAlarmEngine addresses by. Null otherwise.
+/// </param>
 public sealed record DriverAttributeInfo(
     string FullName,
     DriverDataType DriverDataType,
@@ -41,4 +53,21 @@ public sealed record DriverAttributeInfo(
     SecurityClassification SecurityClass,
     bool IsHistorized,
     bool IsAlarm = false,
-    bool WriteIdempotent = false);
+    bool WriteIdempotent = false,
+    NodeSourceKind Source = NodeSourceKind.Driver,
+    string? VirtualTagId = null,
+    string? ScriptedAlarmId = null);
+
+/// <summary>
+///     Per ADR-002 — discriminates which runtime subsystem owns this node's Read/Write/
+///     Subscribe dispatch. <c>Driver</c> = a real IDriver capability surface;
+///     <c>Virtual</c> = a Phase 7 <see cref="DriverAttributeInfo"/>.VirtualTagId'd tag
+///     computed by the VirtualTagEngine; <c>ScriptedAlarm</c> = a scripted Part 9 alarm
+///     materialized by the ScriptedAlarmEngine.
+/// </summary>
+public enum NodeSourceKind
+{
+    Driver = 0,
+    Virtual = 1,
+    ScriptedAlarm = 2,
+}

src/ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian/AlarmHistorianEvent.cs

@@ -0,0 +1,36 @@
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+
+namespace ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian;
+
+/// <summary>
+///     The event shape the historian sink consumes — source-agnostic across scripted
+///     alarms + Galaxy-native + AB CIP ALMD + any future IAlarmSource per Phase 7 plan
+///     decision #15 (sink scope = all alarm sources, not just scripted). A per-alarm
+///     <c>HistorizeToAveva</c> toggle on the producer side gates which events flow.
+/// </summary>
+/// <param name="AlarmId">Stable condition identity.</param>
+/// <param name="EquipmentPath">UNS path of the Equipment node the alarm hangs under. Doubles as the "SourceNode" in Historian's alarm schema.</param>
+/// <param name="AlarmName">Human-readable alarm name.</param>
+/// <param name="AlarmTypeName">Concrete Part 9 subtype — "LimitAlarm" / "DiscreteAlarm" / "OffNormalAlarm" / "AlarmCondition". Used as the Historian "AlarmType" column.</param>
+/// <param name="Severity">Mapped to Historian's numeric priority on the sink side.</param>
+/// <param name="EventKind">
+///     Which state transition this event represents — "Activated" / "Cleared" /
+///     "Acknowledged" / "Confirmed" / "Shelved" / "Unshelved" / "Disabled" / "Enabled" /
+///     "CommentAdded". Free-form string because different alarm sources use different
+///     vocabularies; the Galaxy.Host handler maps to the historian's enum on the wire.
+/// </param>
+/// <param name="Message">Fully-rendered message text — template tokens already resolved upstream.</param>
+/// <param name="User">Operator who triggered the transition. "system" for engine-driven events (shelving expiry, predicate change).</param>
+/// <param name="Comment">Operator-supplied free-form text, if any.</param>
+/// <param name="TimestampUtc">When the transition occurred.</param>
+public sealed record AlarmHistorianEvent(
+    string AlarmId,
+    string EquipmentPath,
+    string AlarmName,
+    string AlarmTypeName,
+    AlarmSeverity Severity,
+    string EventKind,
+    string Message,
+    string User,
+    string? Comment,
+    DateTime TimestampUtc);

src/ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian/IAlarmHistorianSink.cs

@@ -0,0 +1,82 @@
+namespace ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian;
+
+/// <summary>
+///     The historian sink contract — where qualifying alarm events land. Phase 7 plan
+///     decision #17: ingestion routes through Galaxy.Host's pipe so we reuse the
+///     already-loaded <c>aahClientManaged</c> DLLs without loading 32-bit native code
+///     in the main .NET 10 server. Tests use an in-memory fake; production uses
+///     <see cref="SqliteStoreAndForwardSink"/>.
+/// </summary>
+/// <remarks>
+///     <para>
+///         <see cref="EnqueueAsync"/> is fire-and-forget from the engine's perspective —
+///         the sink MUST NOT block the emitting thread. Production implementations
+///         (<see cref="SqliteStoreAndForwardSink"/>) persist to a local SQLite queue
+///         first, then drain asynchronously to the actual historian. Per Phase 7 plan
+///         decision #16, failed downstream writes replay with exponential backoff;
+///         operator actions are never blocked waiting on the historian.
+///     </para>
+///     <para>
+///         <see cref="GetStatus"/> exposes queue depth + drain rate + last error
+///         for the Admin UI <c>/alarms/historian</c> diagnostics page (Stream F).
+///     </para>
+/// </remarks>
+public interface IAlarmHistorianSink
+{
+    /// <summary>Durably enqueue the event. Returns as soon as the queue row is committed.</summary>
+    Task EnqueueAsync(AlarmHistorianEvent evt, CancellationToken cancellationToken);
+
+    /// <summary>Snapshot of current queue depth + drain health.</summary>
+    HistorianSinkStatus GetStatus();
+}
+
+/// <summary>No-op default for tests or deployments that don't historize alarms.</summary>
+public sealed class NullAlarmHistorianSink : IAlarmHistorianSink
+{
+    public static readonly NullAlarmHistorianSink Instance = new();
+    public Task EnqueueAsync(AlarmHistorianEvent evt, CancellationToken cancellationToken) => Task.CompletedTask;
+    public HistorianSinkStatus GetStatus() => new(
+        QueueDepth: 0,
+        DeadLetterDepth: 0,
+        LastDrainUtc: null,
+        LastSuccessUtc: null,
+        LastError: null,
+        DrainState: HistorianDrainState.Disabled);
+}
+
+/// <summary>Diagnostic snapshot surfaced to the Admin UI + /healthz endpoints.</summary>
+public sealed record HistorianSinkStatus(
+    long QueueDepth,
+    long DeadLetterDepth,
+    DateTime? LastDrainUtc,
+    DateTime? LastSuccessUtc,
+    string? LastError,
+    HistorianDrainState DrainState);
+
+/// <summary>Where the drain worker is in its state machine.</summary>
+public enum HistorianDrainState
+{
+    Disabled,
+    Idle,
+    Draining,
+    BackingOff,
+}
+
+/// <summary>Signaled by the Galaxy.Host-side handler when it fails a batch — drain worker uses this to decide retry cadence.</summary>
+public enum HistorianWriteOutcome
+{
+    /// <summary>Successfully persisted to the historian. Remove from queue.</summary>
+    Ack,
+    /// <summary>Transient failure (historian disconnected, timeout, busy). Leave queued; retry after backoff.</summary>
+    RetryPlease,
+    /// <summary>Permanent failure (malformed event, unrecoverable SDK error). Move to dead-letter table.</summary>
+    PermanentFail,
+}
+
+/// <summary>What the drain worker delegates writes to — Stream G wires this to the Galaxy.Host IPC client.</summary>
+public interface IAlarmHistorianWriter
+{
+    /// <summary>Push a batch of events to the historian. Returns one outcome per event, same order.</summary>
+    Task<IReadOnlyList<HistorianWriteOutcome>> WriteBatchAsync(
+        IReadOnlyList<AlarmHistorianEvent> batch, CancellationToken cancellationToken);
+}

src/ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian/SqliteStoreAndForwardSink.cs

@@ -0,0 +1,397 @@
+using System.Text.Json;
+using Microsoft.Data.Sqlite;
+using Serilog;
+
+namespace ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian;
+
+/// <summary>
+///     Phase 7 plan decisions #16–#17 implementation: durable SQLite queue on the node
+///     absorbs every qualifying alarm event, a drain worker batches rows to Galaxy.Host
+///     via <see cref="IAlarmHistorianWriter"/> on an exponential-backoff cadence, and
+///     operator acks never block on the historian being reachable.
+/// </summary>
+/// <remarks>
+///     <para>
+///         Queue schema:
+///         <code>
+///         CREATE TABLE Queue (
+///             RowId INTEGER PRIMARY KEY AUTOINCREMENT,
+///             AlarmId TEXT NOT NULL,
+///             EnqueuedUtc TEXT NOT NULL,
+///             PayloadJson TEXT NOT NULL,
+///             AttemptCount INTEGER NOT NULL DEFAULT 0,
+///             LastAttemptUtc TEXT NULL,
+///             LastError TEXT NULL,
+///             DeadLettered INTEGER NOT NULL DEFAULT 0
+///         );
+///         </code>
+///         Dead-lettered rows stay in place for the configured retention window (default
+///         30 days per Phase 7 plan decision #21) so operators can inspect + manually
+///         retry before the sweeper purges them. Regular queue capacity is bounded —
+///         overflow evicts the oldest non-dead-lettered rows with a WARN log.
+///     </para>
+///     <para>
+///         Drain runs on a shared <see cref="System.Threading.Timer"/>. Exponential
+///         backoff on <see cref="HistorianWriteOutcome.RetryPlease"/>: 1s → 2s → 5s →
+///         15s → 60s cap. <see cref="HistorianWriteOutcome.PermanentFail"/> rows flip
+///         the <c>DeadLettered</c> flag on the individual row; neighbors in the batch
+///         still retry on their own cadence.
+///     </para>
+/// </remarks>
+public sealed class SqliteStoreAndForwardSink : IAlarmHistorianSink, IDisposable
+{
+    /// <summary>Default queue capacity — oldest non-dead-lettered rows evicted past this.</summary>
+    public const long DefaultCapacity = 1_000_000;
+    public static readonly TimeSpan DefaultDeadLetterRetention = TimeSpan.FromDays(30);
+
+    private static readonly TimeSpan[] BackoffLadder =
+    [
+        TimeSpan.FromSeconds(1),
+        TimeSpan.FromSeconds(2),
+        TimeSpan.FromSeconds(5),
+        TimeSpan.FromSeconds(15),
+        TimeSpan.FromSeconds(60),
+    ];
+
+    private readonly string _connectionString;
+    private readonly IAlarmHistorianWriter _writer;
+    private readonly ILogger _logger;
+    private readonly int _batchSize;
+    private readonly long _capacity;
+    private readonly TimeSpan _deadLetterRetention;
+    private readonly Func<DateTime> _clock;
+
+    private readonly SemaphoreSlim _drainGate = new(1, 1);
+    private Timer? _drainTimer;
+    private int _backoffIndex;
+    private DateTime? _lastDrainUtc;
+    private DateTime? _lastSuccessUtc;
+    private string? _lastError;
+    private HistorianDrainState _drainState = HistorianDrainState.Idle;
+    private bool _disposed;
+
+    public SqliteStoreAndForwardSink(
+        string databasePath,
+        IAlarmHistorianWriter writer,
+        ILogger logger,
+        int batchSize = 100,
+        long capacity = DefaultCapacity,
+        TimeSpan? deadLetterRetention = null,
+        Func<DateTime>? clock = null)
+    {
+        if (string.IsNullOrWhiteSpace(databasePath))
+            throw new ArgumentException("Database path required.", nameof(databasePath));
+        _writer = writer ?? throw new ArgumentNullException(nameof(writer));
+        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+        _batchSize = batchSize > 0 ? batchSize : throw new ArgumentOutOfRangeException(nameof(batchSize));
+        _capacity = capacity > 0 ? capacity : throw new ArgumentOutOfRangeException(nameof(capacity));
+        _deadLetterRetention = deadLetterRetention ?? DefaultDeadLetterRetention;
+        _clock = clock ?? (() => DateTime.UtcNow);
+        _connectionString = $"Data Source={databasePath}";
+
+        InitializeSchema();
+    }
+
+    /// <summary>
+    ///     Start the background drain worker. Not started automatically so tests can
+    ///     drive <see cref="DrainOnceAsync"/> deterministically.
+    /// </summary>
+    public void StartDrainLoop(TimeSpan tickInterval)
+    {
+        if (_disposed) throw new ObjectDisposedException(nameof(SqliteStoreAndForwardSink));
+        _drainTimer?.Dispose();
+        _drainTimer = new Timer(_ => _ = DrainOnceAsync(CancellationToken.None),
+            null, tickInterval, tickInterval);
+    }
+
+    public Task EnqueueAsync(AlarmHistorianEvent evt, CancellationToken cancellationToken)
+    {
+        if (evt is null) throw new ArgumentNullException(nameof(evt));
+        if (_disposed) throw new ObjectDisposedException(nameof(SqliteStoreAndForwardSink));
+
+        using var conn = new SqliteConnection(_connectionString);
+        conn.Open();
+
+        EnforceCapacity(conn);
+
+        using var cmd = conn.CreateCommand();
+        cmd.CommandText = """
+            INSERT INTO Queue (AlarmId, EnqueuedUtc, PayloadJson, AttemptCount)
+            VALUES ($alarmId, $enqueued, $payload, 0);
+            """;
+        cmd.Parameters.AddWithValue("$alarmId", evt.AlarmId);
+        cmd.Parameters.AddWithValue("$enqueued", _clock().ToString("O"));
+        cmd.Parameters.AddWithValue("$payload", JsonSerializer.Serialize(evt));
+        cmd.ExecuteNonQuery();
+        return Task.CompletedTask;
+    }
+
+    /// <summary>
+    ///     Read up to <see cref="_batchSize"/> queued rows, forward through the writer,
+    ///     remove Ack'd rows, dead-letter PermanentFail rows, and extend the backoff
+    ///     on RetryPlease. Safe to call from multiple threads; the semaphore enforces
+    ///     serial execution.
+    /// </summary>
+    public async Task DrainOnceAsync(CancellationToken ct)
+    {
+        if (_disposed) return;
+        if (!await _drainGate.WaitAsync(0, ct).ConfigureAwait(false)) return;
+        try
+        {
+            _drainState = HistorianDrainState.Draining;
+            _lastDrainUtc = _clock();
+
+            PurgeAgedDeadLetters();
+            var (rowIds, events) = ReadBatch();
+            if (rowIds.Count == 0)
+            {
+                _drainState = HistorianDrainState.Idle;
+                return;
+            }
+
+            IReadOnlyList<HistorianWriteOutcome> outcomes;
+            try
+            {
+                outcomes = await _writer.WriteBatchAsync(events, ct).ConfigureAwait(false);
+                _lastError = null;
+            }
+            catch (OperationCanceledException)
+            {
+                throw;
+            }
+            catch (Exception ex)
+            {
+                // Writer-side exception — treat entire batch as RetryPlease.
+                _lastError = ex.Message;
+                _logger.Warning(ex, "Historian writer threw on batch of {Count}; deferring retry", events.Count);
+                BumpBackoff();
+                _drainState = HistorianDrainState.BackingOff;
+                return;
+            }
+
+            if (outcomes.Count != events.Count)
+                throw new InvalidOperationException(
+                    $"Writer returned {outcomes.Count} outcomes for {events.Count} events — expected 1:1");
+
+            using var conn = new SqliteConnection(_connectionString);
+            conn.Open();
+            using var tx = conn.BeginTransaction();
+            for (var i = 0; i < outcomes.Count; i++)
+            {
+                var outcome = outcomes[i];
+                var rowId = rowIds[i];
+                switch (outcome)
+                {
+                    case HistorianWriteOutcome.Ack:
+                        DeleteRow(conn, tx, rowId);
+                        break;
+                    case HistorianWriteOutcome.PermanentFail:
+                        DeadLetterRow(conn, tx, rowId, $"permanent fail at {_clock():O}");
+                        break;
+                    case HistorianWriteOutcome.RetryPlease:
+                        BumpAttempt(conn, tx, rowId, "retry-please");
+                        break;
+                }
+            }
+            tx.Commit();
+
+            var acks = outcomes.Count(o => o == HistorianWriteOutcome.Ack);
+            if (acks > 0) _lastSuccessUtc = _clock();
+
+            if (outcomes.Any(o => o == HistorianWriteOutcome.RetryPlease))
+            {
+                BumpBackoff();
+                _drainState = HistorianDrainState.BackingOff;
+            }
+            else
+            {
+                ResetBackoff();
+                _drainState = HistorianDrainState.Idle;
+            }
+        }
+        finally
+        {
+            _drainGate.Release();
+        }
+    }
+
+    public HistorianSinkStatus GetStatus()
+    {
+        using var conn = new SqliteConnection(_connectionString);
+        conn.Open();
+
+        long queued;
+        long deadlettered;
+        using (var cmd = conn.CreateCommand())
+        {
+            cmd.CommandText = "SELECT COUNT(*) FROM Queue WHERE DeadLettered = 0";
+            queued = (long)(cmd.ExecuteScalar() ?? 0L);
+        }
+        using (var cmd = conn.CreateCommand())
+        {
+            cmd.CommandText = "SELECT COUNT(*) FROM Queue WHERE DeadLettered = 1";
+            deadlettered = (long)(cmd.ExecuteScalar() ?? 0L);
+        }
+
+        return new HistorianSinkStatus(
+            QueueDepth: queued,
+            DeadLetterDepth: deadlettered,
+            LastDrainUtc: _lastDrainUtc,
+            LastSuccessUtc: _lastSuccessUtc,
+            LastError: _lastError,
+            DrainState: _drainState);
+    }
+
+    /// <summary>Operator action from Admin UI — retry every dead-lettered row. Non-cascading: they rejoin the regular queue + get a fresh backoff.</summary>
+    public int RetryDeadLettered()
+    {
+        using var conn = new SqliteConnection(_connectionString);
+        conn.Open();
+        using var cmd = conn.CreateCommand();
+        cmd.CommandText = "UPDATE Queue SET DeadLettered = 0, AttemptCount = 0, LastError = NULL WHERE DeadLettered = 1";
+        return cmd.ExecuteNonQuery();
+    }
+
+    private (List<long> rowIds, List<AlarmHistorianEvent> events) ReadBatch()
+    {
+        var rowIds = new List<long>();
+        var events = new List<AlarmHistorianEvent>();
+        using var conn = new SqliteConnection(_connectionString);
+        conn.Open();
+        using var cmd = conn.CreateCommand();
+        cmd.CommandText = """
+            SELECT RowId, PayloadJson FROM Queue
+            WHERE DeadLettered = 0
+            ORDER BY RowId ASC
+            LIMIT $limit
+            """;
+        cmd.Parameters.AddWithValue("$limit", _batchSize);
+        using var reader = cmd.ExecuteReader();
+        while (reader.Read())
+        {
+            rowIds.Add(reader.GetInt64(0));
+            var payload = reader.GetString(1);
+            var evt = JsonSerializer.Deserialize<AlarmHistorianEvent>(payload);
+            if (evt is not null) events.Add(evt);
+        }
+        return (rowIds, events);
+    }
+
+    private static void DeleteRow(SqliteConnection conn, SqliteTransaction tx, long rowId)
+    {
+        using var cmd = conn.CreateCommand();
+        cmd.Transaction = tx;
+        cmd.CommandText = "DELETE FROM Queue WHERE RowId = $id";
+        cmd.Parameters.AddWithValue("$id", rowId);
+        cmd.ExecuteNonQuery();
+    }
+
+    private void DeadLetterRow(SqliteConnection conn, SqliteTransaction tx, long rowId, string reason)
+    {
+        using var cmd = conn.CreateCommand();
+        cmd.Transaction = tx;
+        cmd.CommandText = """
+            UPDATE Queue SET DeadLettered = 1, LastAttemptUtc = $now, LastError = $err, AttemptCount = AttemptCount + 1
+            WHERE RowId = $id
+            """;
+        cmd.Parameters.AddWithValue("$now", _clock().ToString("O"));
+        cmd.Parameters.AddWithValue("$err", reason);
+        cmd.Parameters.AddWithValue("$id", rowId);
+        cmd.ExecuteNonQuery();
+    }
+
+    private void BumpAttempt(SqliteConnection conn, SqliteTransaction tx, long rowId, string reason)
+    {
+        using var cmd = conn.CreateCommand();
+        cmd.Transaction = tx;
+        cmd.CommandText = """
+            UPDATE Queue SET LastAttemptUtc = $now, LastError = $err, AttemptCount = AttemptCount + 1
+            WHERE RowId = $id
+            """;
+        cmd.Parameters.AddWithValue("$now", _clock().ToString("O"));
+        cmd.Parameters.AddWithValue("$err", reason);
+        cmd.Parameters.AddWithValue("$id", rowId);
+        cmd.ExecuteNonQuery();
+    }
+
+    private void EnforceCapacity(SqliteConnection conn)
+    {
+        // Count non-dead-lettered rows only — dead-lettered rows retain for
+        // post-mortem per the configured retention window.
+        long count;
+        using (var cmd = conn.CreateCommand())
+        {
+            cmd.CommandText = "SELECT COUNT(*) FROM Queue WHERE DeadLettered = 0";
+            count = (long)(cmd.ExecuteScalar() ?? 0L);
+        }
+        if (count < _capacity) return;
+
+        var toEvict = count - _capacity + 1;
+        using (var cmd = conn.CreateCommand())
+        {
+            cmd.CommandText = """
+                DELETE FROM Queue
+                WHERE RowId IN (
+                    SELECT RowId FROM Queue
+                    WHERE DeadLettered = 0
+                    ORDER BY RowId ASC
+                    LIMIT $n
+                )
+                """;
+            cmd.Parameters.AddWithValue("$n", toEvict);
+            cmd.ExecuteNonQuery();
+        }
+        _logger.Warning(
+            "Historian queue at capacity {Cap} — evicted {Count} oldest row(s) to make room",
+            _capacity, toEvict);
+    }
+
+    private void PurgeAgedDeadLetters()
+    {
+        var cutoff = (_clock() - _deadLetterRetention).ToString("O");
+        using var conn = new SqliteConnection(_connectionString);
+        conn.Open();
+        using var cmd = conn.CreateCommand();
+        cmd.CommandText = """
+            DELETE FROM Queue
+            WHERE DeadLettered = 1 AND LastAttemptUtc IS NOT NULL AND LastAttemptUtc < $cutoff
+            """;
+        cmd.Parameters.AddWithValue("$cutoff", cutoff);
+        var purged = cmd.ExecuteNonQuery();
+        if (purged > 0)
+            _logger.Information("Purged {Count} dead-lettered row(s) past retention window", purged);
+    }
+
+    private void InitializeSchema()
+    {
+        using var conn = new SqliteConnection(_connectionString);
+        conn.Open();
+        using var cmd = conn.CreateCommand();
+        cmd.CommandText = """
+            CREATE TABLE IF NOT EXISTS Queue (
+                RowId INTEGER PRIMARY KEY AUTOINCREMENT,
+                AlarmId TEXT NOT NULL,
+                EnqueuedUtc TEXT NOT NULL,
+                PayloadJson TEXT NOT NULL,
+                AttemptCount INTEGER NOT NULL DEFAULT 0,
+                LastAttemptUtc TEXT NULL,
+                LastError TEXT NULL,
+                DeadLettered INTEGER NOT NULL DEFAULT 0
+            );
+            CREATE INDEX IF NOT EXISTS IX_Queue_Drain ON Queue (DeadLettered, RowId);
+            """;
+        cmd.ExecuteNonQuery();
+    }
+
+    private void BumpBackoff() => _backoffIndex = Math.Min(_backoffIndex + 1, BackoffLadder.Length - 1);
+    private void ResetBackoff() => _backoffIndex = 0;
+    public TimeSpan CurrentBackoff => BackoffLadder[_backoffIndex];
+
+    public void Dispose()
+    {
+        if (_disposed) return;
+        _disposed = true;
+        _drainTimer?.Dispose();
+        _drainGate.Dispose();
+    }
+}

src/ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian/ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian.csproj

@@ -0,0 +1,32 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <TargetFramework>net10.0</TargetFramework>
+        <Nullable>enable</Nullable>
+        <ImplicitUsings>enable</ImplicitUsings>
+        <LangVersion>latest</LangVersion>
+        <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+        <GenerateDocumentationFile>true</GenerateDocumentationFile>
+        <NoWarn>$(NoWarn);CS1591</NoWarn>
+        <RootNamespace>ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian</RootNamespace>
+    </PropertyGroup>
+
+    <ItemGroup>
+        <PackageReference Include="Microsoft.Data.Sqlite" Version="9.0.0"/>
+        <PackageReference Include="Serilog" Version="4.2.0"/>
+    </ItemGroup>
+
+    <ItemGroup>
+        <ProjectReference Include="..\ZB.MOM.WW.OtOpcUa.Core.Abstractions\ZB.MOM.WW.OtOpcUa.Core.Abstractions.csproj"/>
+    </ItemGroup>
+
+    <ItemGroup>
+        <InternalsVisibleTo Include="ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian.Tests"/>
+    </ItemGroup>
+
+    <ItemGroup>
+        <NuGetAuditSuppress Include="https://github.com/advisories/GHSA-37gx-xxp4-5rgx"/>
+        <NuGetAuditSuppress Include="https://github.com/advisories/GHSA-w3x6-4m5h-cxqf"/>
+    </ItemGroup>
+
+</Project>

src/ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms/AlarmConditionState.cs

@@ -0,0 +1,84 @@
+namespace ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms;
+
+/// <summary>
+///     Persistent per-alarm state tracked by the Part 9 state machine. Every field
+///     carried here either participates in the state machine or contributes to the
+///     audit trail required by Phase 7 plan decision #14 (GxP / 21 CFR Part 11).
+/// </summary>
+/// <remarks>
+///     <para>
+///         <see cref="Active"/> is re-derived from the predicate at startup per Phase 7
+///         decision #14 — the engine runs every alarm's predicate against current tag
+///         values at <c>Load</c>, overriding whatever Active state is in the store.
+///         Every other state field persists verbatim across server restarts so
+///         operators don't re-ack active alarms after an outage + shelved alarms stay
+///         shelved + audit history survives.
+///     </para>
+///     <para>
+///         <see cref="Comments"/> is append-only; comments + ack/confirm user identities
+///         are the audit surface regulators consume. The engine never rewrites past
+///         entries.
+///     </para>
+/// </remarks>
+public sealed record AlarmConditionState(
+    string AlarmId,
+    AlarmEnabledState Enabled,
+    AlarmActiveState Active,
+    AlarmAckedState Acked,
+    AlarmConfirmedState Confirmed,
+    ShelvingState Shelving,
+    DateTime LastTransitionUtc,
+    DateTime? LastActiveUtc,
+    DateTime? LastClearedUtc,
+    DateTime? LastAckUtc,
+    string? LastAckUser,
+    string? LastAckComment,
+    DateTime? LastConfirmUtc,
+    string? LastConfirmUser,
+    string? LastConfirmComment,
+    IReadOnlyList<AlarmComment> Comments)
+{
+    /// <summary>Initial-load state for a newly registered alarm — everything in the "no-event" position.</summary>
+    public static AlarmConditionState Fresh(string alarmId, DateTime nowUtc) => new(
+        AlarmId: alarmId,
+        Enabled: AlarmEnabledState.Enabled,
+        Active: AlarmActiveState.Inactive,
+        Acked: AlarmAckedState.Acknowledged,
+        Confirmed: AlarmConfirmedState.Confirmed,
+        Shelving: ShelvingState.Unshelved,
+        LastTransitionUtc: nowUtc,
+        LastActiveUtc: null,
+        LastClearedUtc: null,
+        LastAckUtc: null,
+        LastAckUser: null,
+        LastAckComment: null,
+        LastConfirmUtc: null,
+        LastConfirmUser: null,
+        LastConfirmComment: null,
+        Comments: []);
+}
+
+/// <summary>
+///     Shelving state — kind plus, for <see cref="ShelvingKind.Timed"/>, the UTC
+///     timestamp at which the shelving auto-expires. The engine polls the timer on its
+///     evaluation cadence; callers should not rely on millisecond-precision expiry.
+/// </summary>
+public sealed record ShelvingState(ShelvingKind Kind, DateTime? UnshelveAtUtc)
+{
+    public static readonly ShelvingState Unshelved = new(ShelvingKind.Unshelved, null);
+}
+
+/// <summary>
+///     A single append-only audit record — acknowledgement / confirmation / explicit
+///     comment / shelving action. Every entry carries a monotonic UTC timestamp plus the
+///     user identity Phase 6.2 authenticated.
+/// </summary>
+/// <param name="TimestampUtc">When the action happened.</param>
+/// <param name="User">OS / LDAP identity of the actor. For engine-internal events (shelving expiry, startup recovery) this is <c>"system"</c>.</param>
+/// <param name="Kind">Human-readable classification — "Acknowledge", "Confirm", "ShelveOneShot", "ShelveTimed", "Unshelve", "AddComment", "Enable", "Disable", "AutoUnshelve".</param>
+/// <param name="Text">Operator-supplied comment or engine-generated message.</param>
+public sealed record AlarmComment(
+    DateTime TimestampUtc,
+    string User,
+    string Kind,
+    string Text);

src/ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms/AlarmPredicateContext.cs

@@ -0,0 +1,55 @@
+using Serilog;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+using ZB.MOM.WW.OtOpcUa.Core.Scripting;
+
+namespace ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms;
+
+/// <summary>
+///     <see cref="ScriptContext"/> subclass for alarm predicate evaluation. Reads from
+///     the engine's shared tag cache (driver + virtual tags), writes are rejected —
+///     predicates must be side-effect free so their output doesn't depend on evaluation
+///     order or drive cascade behavior.
+/// </summary>
+/// <remarks>
+///     Per Phase 7 plan Shape A decision, alarm scripts are one-script-per-alarm
+///     returning <c>bool</c>. They read any tag they want but should not write
+///     anything (the owning alarm's state is tracked by the engine, not the script).
+/// </remarks>
+public sealed class AlarmPredicateContext : ScriptContext
+{
+    private readonly IReadOnlyDictionary<string, DataValueSnapshot> _readCache;
+    private readonly Func<DateTime> _clock;
+
+    public AlarmPredicateContext(
+        IReadOnlyDictionary<string, DataValueSnapshot> readCache,
+        ILogger logger,
+        Func<DateTime>? clock = null)
+    {
+        _readCache = readCache ?? throw new ArgumentNullException(nameof(readCache));
+        Logger = logger ?? throw new ArgumentNullException(nameof(logger));
+        _clock = clock ?? (() => DateTime.UtcNow);
+    }
+
+    public override DataValueSnapshot GetTag(string path)
+    {
+        if (string.IsNullOrWhiteSpace(path))
+            return new DataValueSnapshot(null, 0x80340000u, null, _clock());
+        return _readCache.TryGetValue(path, out var v)
+            ? v
+            : new DataValueSnapshot(null, 0x80340000u, null, _clock());
+    }
+
+    public override void SetVirtualTag(string path, object? value)
+    {
+        // Predicates must be pure — writing from an alarm script couples alarm state to
+        // virtual-tag state in a way that's near-impossible to reason about. Rejected
+        // at runtime with a clear message; operators see it in the scripts-*.log.
+        throw new InvalidOperationException(
+            "Alarm predicate scripts cannot write to virtual tags. Move the write logic " +
+            "into a virtual tag whose value the alarm predicate then reads.");
+    }
+
+    public override DateTime Now => _clock();
+
+    public override ILogger Logger { get; }
+}

src/ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms/AlarmTypes.cs

@@ -0,0 +1,40 @@
+namespace ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms;
+
+/// <summary>
+///     The concrete OPC UA Part 9 alarm subtype a scripted alarm materializes as. The
+///     engine's internal state machine is identical regardless of kind — the
+///     <c>AlarmKind</c> only affects how the alarm node appears to OPC UA clients
+///     (which ObjectType it maps to) and what diagnostic fields are populated.
+/// </summary>
+public enum AlarmKind
+{
+    /// <summary>Base AlarmConditionType — no numeric or discrete interpretation.</summary>
+    AlarmCondition,
+    /// <summary>LimitAlarmType — the condition reflects a numeric setpoint / threshold breach.</summary>
+    LimitAlarm,
+    /// <summary>DiscreteAlarmType — the condition reflects a specific discrete value match.</summary>
+    DiscreteAlarm,
+    /// <summary>OffNormalAlarmType — the condition reflects deviation from a configured "normal" state.</summary>
+    OffNormalAlarm,
+}
+
+/// <summary>OPC UA Part 9 EnabledState — operator-controlled alarm enable/disable.</summary>
+public enum AlarmEnabledState { Enabled, Disabled }
+
+/// <summary>OPC UA Part 9 ActiveState — reflects the current predicate truth.</summary>
+public enum AlarmActiveState { Inactive, Active }
+
+/// <summary>OPC UA Part 9 AckedState — operator has acknowledged the active transition.</summary>
+public enum AlarmAckedState { Unacknowledged, Acknowledged }
+
+/// <summary>OPC UA Part 9 ConfirmedState — operator has confirmed the clear transition.</summary>
+public enum AlarmConfirmedState { Unconfirmed, Confirmed }
+
+/// <summary>
+///     OPC UA Part 9 shelving mode.
+///     <see cref="OneShot"/> suppresses the next active transition; once cleared
+///     the shelving expires and the alarm returns to normal behavior.
+///     <see cref="Timed"/> suppresses until a configured expiry timestamp passes.
+///     <see cref="Unshelved"/> is the default state — no suppression.
+/// </summary>
+public enum ShelvingKind { Unshelved, OneShot, Timed }

src/ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms/IAlarmStateStore.cs

@@ -0,0 +1,47 @@
+using System.Collections.Concurrent;
+
+namespace ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms;
+
+/// <summary>
+///     Persistence for <see cref="AlarmConditionState"/> across server restarts. Phase 7
+///     plan decision #14: operator-supplied state (EnabledState / AckedState /
+///     ConfirmedState / ShelvingState + audit trail) persists; ActiveState is
+///     recomputed from the live predicate on startup so operators never re-ack.
+/// </summary>
+/// <remarks>
+///     Stream E wires this to a SQL-backed store against the <c>ScriptedAlarmState</c>
+///     table with audit logging through <see cref="Core.Abstractions"/> IAuditLogger.
+///     Tests + local dev use <see cref="InMemoryAlarmStateStore"/>.
+/// </remarks>
+public interface IAlarmStateStore
+{
+    Task<AlarmConditionState?> LoadAsync(string alarmId, CancellationToken ct);
+    Task<IReadOnlyList<AlarmConditionState>> LoadAllAsync(CancellationToken ct);
+    Task SaveAsync(AlarmConditionState state, CancellationToken ct);
+    Task RemoveAsync(string alarmId, CancellationToken ct);
+}
+
+/// <summary>In-memory default — used by tests + by dev deployments without a SQL backend.</summary>
+public sealed class InMemoryAlarmStateStore : IAlarmStateStore
+{
+    private readonly ConcurrentDictionary<string, AlarmConditionState> _map
+        = new(StringComparer.Ordinal);
+
+    public Task<AlarmConditionState?> LoadAsync(string alarmId, CancellationToken ct)
+        => Task.FromResult(_map.TryGetValue(alarmId, out var v) ? v : null);
+
+    public Task<IReadOnlyList<AlarmConditionState>> LoadAllAsync(CancellationToken ct)
+        => Task.FromResult<IReadOnlyList<AlarmConditionState>>(_map.Values.ToArray());
+
+    public Task SaveAsync(AlarmConditionState state, CancellationToken ct)
+    {
+        _map[state.AlarmId] = state;
+        return Task.CompletedTask;
+    }
+
+    public Task RemoveAsync(string alarmId, CancellationToken ct)
+    {
+        _map.TryRemove(alarmId, out _);
+        return Task.CompletedTask;
+    }
+}

src/ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms/MessageTemplate.cs

@@ -0,0 +1,64 @@
+using System.Text.RegularExpressions;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+
+namespace ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms;
+
+/// <summary>
+///     Per Phase 7 plan decision #13, alarm messages are static-with-substitution
+///     templates. The engine resolves <c>{TagPath}</c> tokens at event emission time
+///     against current tag values; unresolvable tokens become <c>{?}</c> so the event
+///     still fires but the operator sees where the reference broke.
+/// </summary>
+/// <remarks>
+///     <para>
+///         Token syntax: <c>{path/with/slashes}</c>. Brace-stripped the contents must
+///         match a path the caller's resolver function can look up. No escaping
+///         currently — if you need literal braces in the message, reach for a feature
+///         request.
+///     </para>
+///     <para>
+///         Pure function. Same inputs always produce the same string. Tests verify the
+///         edge cases (no tokens / one token / many / nested / unresolvable / bad
+///         quality / null value).
+///     </para>
+/// </remarks>
+public static class MessageTemplate
+{
+    private static readonly Regex TokenRegex = new(@"\{([^{}]+)\}",
+        RegexOptions.Compiled | RegexOptions.CultureInvariant);
+
+    /// <summary>
+    ///     Resolve every <c>{path}</c> token in <paramref name="template"/> using
+    ///     <paramref name="resolveTag"/>. Tokens whose returned <see cref="DataValueSnapshot"/>
+    ///     has a non-Good <see cref="DataValueSnapshot.StatusCode"/> or a null
+    ///     <see cref="DataValueSnapshot.Value"/> resolve to <c>{?}</c>.
+    /// </summary>
+    public static string Resolve(string template, Func<string, DataValueSnapshot?> resolveTag)
+    {
+        if (string.IsNullOrEmpty(template)) return template ?? string.Empty;
+        if (resolveTag is null) throw new ArgumentNullException(nameof(resolveTag));
+
+        return TokenRegex.Replace(template, match =>
+        {
+            var path = match.Groups[1].Value.Trim();
+            if (path.Length == 0) return "{?}";
+            var snap = resolveTag(path);
+            if (snap is null) return "{?}";
+            if (snap.StatusCode != 0u) return "{?}";
+            return snap.Value?.ToString() ?? "{?}";
+        });
+    }
+
+    /// <summary>Enumerate the token paths the template references. Used at publish time to validate references exist.</summary>
+    public static IReadOnlyList<string> ExtractTokenPaths(string? template)
+    {
+        if (string.IsNullOrEmpty(template)) return Array.Empty<string>();
+        var tokens = new List<string>();
+        foreach (Match m in TokenRegex.Matches(template))
+        {
+            var path = m.Groups[1].Value.Trim();
+            if (path.Length > 0) tokens.Add(path);
+        }
+        return tokens;
+    }
+}

src/ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms/Part9StateMachine.cs

@@ -0,0 +1,294 @@
+namespace ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms;
+
+/// <summary>
+///     Pure functions for OPC UA Part 9 alarm-condition state transitions. Input = the
+///     current <see cref="AlarmConditionState"/> + the event; output = the new state +
+///     optional emission hint. The engine calls these; persistence happens around them.
+/// </summary>
+/// <remarks>
+///     <para>
+///         No instance state, no I/O, no mutation of the input record. Every transition
+///         returns a fresh record. Makes the state machine trivially unit-testable —
+///         tests assert on (input, event) -> (output) without standing anything else up.
+///     </para>
+///     <para>
+///         Two invariants the machine enforces:
+///         (1) Disabled alarms never transition ActiveState / AckedState / ConfirmedState
+///         — all predicate evaluations while disabled produce a no-op result and a
+///         diagnostic log line. Re-enable restores normal flow with ActiveState
+///         re-derived from the next predicate evaluation.
+///         (2) Shelved alarms (OneShot / Timed) don't fire active transitions to
+///         subscribers, but the state record still advances so that when shelving
+///         expires the ActiveState reflects current reality. OneShot expires on the
+///         next clear; Timed expires at <see cref="ShelvingState.UnshelveAtUtc"/>.
+///     </para>
+/// </remarks>
+public static class Part9StateMachine
+{
+    /// <summary>
+    ///     Apply a predicate re-evaluation result. Handles activation, clearing,
+    ///     branch-stack increment when a new active arrives while prior active is
+    ///     still un-acked, and shelving suppression.
+    /// </summary>
+    public static TransitionResult ApplyPredicate(
+        AlarmConditionState current,
+        bool predicateTrue,
+        DateTime nowUtc)
+    {
+        if (current.Enabled == AlarmEnabledState.Disabled)
+            return TransitionResult.NoOp(current, "disabled — predicate result ignored");
+
+        // Expire timed shelving if the configured clock has passed.
+        var shelving = MaybeExpireShelving(current.Shelving, nowUtc);
+        var stateWithShelving = current with { Shelving = shelving };
+
+        // Shelved alarms still update state but skip event emission.
+        var shelved = shelving.Kind != ShelvingKind.Unshelved;
+
+        if (predicateTrue && current.Active == AlarmActiveState.Inactive)
+        {
+            // Inactive -> Active transition.
+            // OneShotShelving is consumed on the NEXT clear, not activation — so we
+            // still suppress this transition's emission.
+            var next = stateWithShelving with
+            {
+                Active = AlarmActiveState.Active,
+                Acked = AlarmAckedState.Unacknowledged,
+                Confirmed = AlarmConfirmedState.Unconfirmed,
+                LastActiveUtc = nowUtc,
+                LastTransitionUtc = nowUtc,
+            };
+            return new TransitionResult(next, shelved ? EmissionKind.Suppressed : EmissionKind.Activated);
+        }
+
+        if (!predicateTrue && current.Active == AlarmActiveState.Active)
+        {
+            // Active -> Inactive transition.
+            var next = stateWithShelving with
+            {
+                Active = AlarmActiveState.Inactive,
+                LastClearedUtc = nowUtc,
+                LastTransitionUtc = nowUtc,
+                // OneShotShelving expires on clear — resetting here so the next
+                // activation fires normally.
+                Shelving = shelving.Kind == ShelvingKind.OneShot
+                    ? ShelvingState.Unshelved
+                    : shelving,
+            };
+            return new TransitionResult(next, shelved ? EmissionKind.Suppressed : EmissionKind.Cleared);
+        }
+
+        // Predicate matches current Active — no state change beyond possible shelving
+        // expiry.
+        return new TransitionResult(stateWithShelving, EmissionKind.None);
+    }
+
+    /// <summary>Operator acknowledges the currently-active transition.</summary>
+    public static TransitionResult ApplyAcknowledge(
+        AlarmConditionState current,
+        string user,
+        string? comment,
+        DateTime nowUtc)
+    {
+        if (string.IsNullOrWhiteSpace(user))
+            throw new ArgumentException("User identity required for audit.", nameof(user));
+
+        if (current.Acked == AlarmAckedState.Acknowledged)
+            return TransitionResult.NoOp(current, "already acknowledged");
+
+        var audit = AppendComment(current.Comments, nowUtc, user, "Acknowledge", comment);
+        var next = current with
+        {
+            Acked = AlarmAckedState.Acknowledged,
+            LastAckUtc = nowUtc,
+            LastAckUser = user,
+            LastAckComment = comment,
+            LastTransitionUtc = nowUtc,
+            Comments = audit,
+        };
+        return new TransitionResult(next, EmissionKind.Acknowledged);
+    }
+
+    /// <summary>Operator confirms the cleared transition. Part 9 requires confirm after clear for retain-flag alarms.</summary>
+    public static TransitionResult ApplyConfirm(
+        AlarmConditionState current,
+        string user,
+        string? comment,
+        DateTime nowUtc)
+    {
+        if (string.IsNullOrWhiteSpace(user))
+            throw new ArgumentException("User identity required for audit.", nameof(user));
+
+        if (current.Confirmed == AlarmConfirmedState.Confirmed)
+            return TransitionResult.NoOp(current, "already confirmed");
+
+        var audit = AppendComment(current.Comments, nowUtc, user, "Confirm", comment);
+        var next = current with
+        {
+            Confirmed = AlarmConfirmedState.Confirmed,
+            LastConfirmUtc = nowUtc,
+            LastConfirmUser = user,
+            LastConfirmComment = comment,
+            LastTransitionUtc = nowUtc,
+            Comments = audit,
+        };
+        return new TransitionResult(next, EmissionKind.Confirmed);
+    }
+
+    public static TransitionResult ApplyOneShotShelve(
+        AlarmConditionState current, string user, DateTime nowUtc)
+    {
+        if (string.IsNullOrWhiteSpace(user)) throw new ArgumentException("User required.", nameof(user));
+        if (current.Shelving.Kind == ShelvingKind.OneShot)
+            return TransitionResult.NoOp(current, "already one-shot shelved");
+
+        var audit = AppendComment(current.Comments, nowUtc, user, "ShelveOneShot", null);
+        var next = current with
+        {
+            Shelving = new ShelvingState(ShelvingKind.OneShot, null),
+            LastTransitionUtc = nowUtc,
+            Comments = audit,
+        };
+        return new TransitionResult(next, EmissionKind.Shelved);
+    }
+
+    public static TransitionResult ApplyTimedShelve(
+        AlarmConditionState current, string user, DateTime unshelveAtUtc, DateTime nowUtc)
+    {
+        if (string.IsNullOrWhiteSpace(user)) throw new ArgumentException("User required.", nameof(user));
+        if (unshelveAtUtc <= nowUtc)
+            throw new ArgumentOutOfRangeException(nameof(unshelveAtUtc), "Unshelve time must be in the future.");
+
+        var audit = AppendComment(current.Comments, nowUtc, user, "ShelveTimed",
+            $"UnshelveAtUtc={unshelveAtUtc:O}");
+        var next = current with
+        {
+            Shelving = new ShelvingState(ShelvingKind.Timed, unshelveAtUtc),
+            LastTransitionUtc = nowUtc,
+            Comments = audit,
+        };
+        return new TransitionResult(next, EmissionKind.Shelved);
+    }
+
+    public static TransitionResult ApplyUnshelve(AlarmConditionState current, string user, DateTime nowUtc)
+    {
+        if (string.IsNullOrWhiteSpace(user)) throw new ArgumentException("User required.", nameof(user));
+        if (current.Shelving.Kind == ShelvingKind.Unshelved)
+            return TransitionResult.NoOp(current, "not shelved");
+
+        var audit = AppendComment(current.Comments, nowUtc, user, "Unshelve", null);
+        var next = current with
+        {
+            Shelving = ShelvingState.Unshelved,
+            LastTransitionUtc = nowUtc,
+            Comments = audit,
+        };
+        return new TransitionResult(next, EmissionKind.Unshelved);
+    }
+
+    public static TransitionResult ApplyEnable(AlarmConditionState current, string user, DateTime nowUtc)
+    {
+        if (string.IsNullOrWhiteSpace(user)) throw new ArgumentException("User required.", nameof(user));
+        if (current.Enabled == AlarmEnabledState.Enabled)
+            return TransitionResult.NoOp(current, "already enabled");
+
+        var audit = AppendComment(current.Comments, nowUtc, user, "Enable", null);
+        var next = current with
+        {
+            Enabled = AlarmEnabledState.Enabled,
+            LastTransitionUtc = nowUtc,
+            Comments = audit,
+        };
+        return new TransitionResult(next, EmissionKind.Enabled);
+    }
+
+    public static TransitionResult ApplyDisable(AlarmConditionState current, string user, DateTime nowUtc)
+    {
+        if (string.IsNullOrWhiteSpace(user)) throw new ArgumentException("User required.", nameof(user));
+        if (current.Enabled == AlarmEnabledState.Disabled)
+            return TransitionResult.NoOp(current, "already disabled");
+
+        var audit = AppendComment(current.Comments, nowUtc, user, "Disable", null);
+        var next = current with
+        {
+            Enabled = AlarmEnabledState.Disabled,
+            LastTransitionUtc = nowUtc,
+            Comments = audit,
+        };
+        return new TransitionResult(next, EmissionKind.Disabled);
+    }
+
+    public static TransitionResult ApplyAddComment(
+        AlarmConditionState current, string user, string text, DateTime nowUtc)
+    {
+        if (string.IsNullOrWhiteSpace(user)) throw new ArgumentException("User required.", nameof(user));
+        if (string.IsNullOrWhiteSpace(text)) throw new ArgumentException("Comment text required.", nameof(text));
+
+        var audit = AppendComment(current.Comments, nowUtc, user, "AddComment", text);
+        var next = current with { Comments = audit };
+        return new TransitionResult(next, EmissionKind.CommentAdded);
+    }
+
+    /// <summary>
+    ///     Re-evaluate whether a currently timed-shelved alarm has expired. Returns
+    ///     the (possibly unshelved) state + emission hint so the engine knows to
+    ///     publish an Unshelved event at the right moment.
+    /// </summary>
+    public static TransitionResult ApplyShelvingCheck(AlarmConditionState current, DateTime nowUtc)
+    {
+        if (current.Shelving.Kind != ShelvingKind.Timed) return TransitionResult.None(current);
+        if (current.Shelving.UnshelveAtUtc is DateTime t && nowUtc >= t)
+        {
+            var audit = AppendComment(current.Comments, nowUtc, "system", "AutoUnshelve",
+                $"Timed shelving expired at {nowUtc:O}");
+            var next = current with
+            {
+                Shelving = ShelvingState.Unshelved,
+                LastTransitionUtc = nowUtc,
+                Comments = audit,
+            };
+            return new TransitionResult(next, EmissionKind.Unshelved);
+        }
+        return TransitionResult.None(current);
+    }
+
+    private static ShelvingState MaybeExpireShelving(ShelvingState s, DateTime nowUtc)
+    {
+        if (s.Kind != ShelvingKind.Timed) return s;
+        return s.UnshelveAtUtc is DateTime t && nowUtc >= t ? ShelvingState.Unshelved : s;
+    }
+
+    private static IReadOnlyList<AlarmComment> AppendComment(
+        IReadOnlyList<AlarmComment> existing, DateTime ts, string user, string kind, string? text)
+    {
+        var list = new List<AlarmComment>(existing.Count + 1);
+        list.AddRange(existing);
+        list.Add(new AlarmComment(ts, user, kind, text ?? string.Empty));
+        return list;
+    }
+}
+
+/// <summary>Result of a state-machine operation — new state + what to emit (if anything).</summary>
+public sealed record TransitionResult(AlarmConditionState State, EmissionKind Emission)
+{
+    public static TransitionResult None(AlarmConditionState state) => new(state, EmissionKind.None);
+    public static TransitionResult NoOp(AlarmConditionState state, string reason) => new(state, EmissionKind.None);
+}
+
+/// <summary>What kind of event, if any, the engine should emit after a transition.</summary>
+public enum EmissionKind
+{
+    /// <summary>State did not change meaningfully — no event to emit.</summary>
+    None,
+    /// <summary>Predicate transitioned to true while shelving was suppressing events.</summary>
+    Suppressed,
+    Activated,
+    Cleared,
+    Acknowledged,
+    Confirmed,
+    Shelved,
+    Unshelved,
+    Enabled,
+    Disabled,
+    CommentAdded,
+}

src/ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms/ScriptedAlarmDefinition.cs

@@ -0,0 +1,50 @@
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+
+namespace ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms;
+
+/// <summary>
+///     Operator-authored scripted-alarm configuration. Phase 7 Stream E (config DB schema)
+///     materializes these from the <c>ScriptedAlarm</c> + <c>Script</c> tables on publish.
+/// </summary>
+/// <param name="AlarmId">
+///     Stable identity for the alarm — used as the OPC UA ConditionId + the key in the
+///     state store. Should be globally unique within the cluster; convention is
+///     <c>{EquipmentPath}::{AlarmName}</c>.
+/// </param>
+/// <param name="EquipmentPath">
+///     UNS path of the Equipment node the alarm hangs under. Alarm browse lives here;
+///     ACL binding inherits this equipment's scope per Phase 6.2.
+/// </param>
+/// <param name="AlarmName">Human-readable alarm name — used in the browse tree + Admin UI.</param>
+/// <param name="Kind">Concrete OPC UA Part 9 subtype the alarm materializes as.</param>
+/// <param name="Severity">Static severity per Phase 7 plan decision #13; not currently computed by the predicate.</param>
+/// <param name="MessageTemplate">
+///     Message text with <c>{TagPath}</c> tokens resolved at event-emission time per
+///     Phase 7 plan decision #13. Unresolvable tokens emit <c>{?}</c> + a structured
+///     error so operators can spot stale references.
+/// </param>
+/// <param name="PredicateScriptSource">
+///     Roslyn C# script returning <c>bool</c>. <c>true</c> = alarm condition currently holds (active);
+///     <c>false</c> = condition has cleared. Same sandbox rules as virtual tags per Phase 7 decision #6.
+/// </param>
+/// <param name="HistorizeToAveva">
+///     When true, every transition emission of this alarm flows to the Historian alarm
+///     sink (Stream D). Defaults to true — plant alarm history is usually the
+///     operator's primary diagnostic. Galaxy-native alarms default false since Galaxy
+///     historises them directly.
+/// </param>
+/// <param name="Retain">
+///     Part 9 retain flag — when true, the condition node remains visible after the
+///     predicate clears as long as it has un-acknowledged or un-confirmed transitions.
+///     Default true.
+/// </param>
+public sealed record ScriptedAlarmDefinition(
+    string AlarmId,
+    string EquipmentPath,
+    string AlarmName,
+    AlarmKind Kind,
+    AlarmSeverity Severity,
+    string MessageTemplate,
+    string PredicateScriptSource,
+    bool HistorizeToAveva = true,
+    bool Retain = true);

src/ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms/ScriptedAlarmEngine.cs

@@ -0,0 +1,429 @@
+using System.Collections.Concurrent;
+using Serilog;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+using ZB.MOM.WW.OtOpcUa.Core.Scripting;
+
+namespace ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms;
+
+/// <summary>
+///     Phase 7 scripted-alarm orchestrator. Compiles every configured alarm's predicate
+///     against the Stream A sandbox, subscribes to the referenced upstream tags,
+///     re-evaluates the predicate on every input change + on a shelving-check timer,
+///     applies the resulting transition through <see cref="Part9StateMachine"/>,
+///     persists state via <see cref="IAlarmStateStore"/>, and emits the resulting events
+///     through <see cref="ScriptedAlarmSource"/> (which wires into the existing
+///     <c>IAlarmSource</c> fan-out).
+/// </summary>
+/// <remarks>
+///     <para>
+///         Scripted alarms are leaves in the evaluation DAG — no alarm's state drives
+///         another alarm's predicate. The engine maintains only an inverse index from
+///         upstream tag path → alarms referencing it; no topological sort needed
+///         (unlike the virtual-tag engine).
+///     </para>
+///     <para>
+///         Evaluation errors (script throws, timeout, coercion fail) surface as
+///         structured errors in the dedicated scripts-*.log sink plus a WARN companion
+///         in the main log. The alarm's ActiveState stays at its prior value — the
+///         engine does NOT invent a clear transition just because the predicate broke.
+///         Operators investigating a broken predicate shouldn't see a phantom
+///         clear-event preceding the failure.
+///     </para>
+/// </remarks>
+public sealed class ScriptedAlarmEngine : IDisposable
+{
+    private readonly ITagUpstreamSource _upstream;
+    private readonly IAlarmStateStore _store;
+    private readonly ScriptLoggerFactory _loggerFactory;
+    private readonly ILogger _engineLogger;
+    private readonly Func<DateTime> _clock;
+    private readonly TimeSpan _scriptTimeout;
+
+    private readonly Dictionary<string, AlarmState> _alarms = new(StringComparer.Ordinal);
+    private readonly ConcurrentDictionary<string, DataValueSnapshot> _valueCache
+        = new(StringComparer.Ordinal);
+    private readonly Dictionary<string, HashSet<string>> _alarmsReferencing
+        = new(StringComparer.Ordinal); // tag path -> alarm ids
+
+    private readonly List<IDisposable> _upstreamSubscriptions = [];
+    private readonly SemaphoreSlim _evalGate = new(1, 1);
+    private Timer? _shelvingTimer;
+    private bool _loaded;
+    private bool _disposed;
+
+    public ScriptedAlarmEngine(
+        ITagUpstreamSource upstream,
+        IAlarmStateStore store,
+        ScriptLoggerFactory loggerFactory,
+        ILogger engineLogger,
+        Func<DateTime>? clock = null,
+        TimeSpan? scriptTimeout = null)
+    {
+        _upstream = upstream ?? throw new ArgumentNullException(nameof(upstream));
+        _store = store ?? throw new ArgumentNullException(nameof(store));
+        _loggerFactory = loggerFactory ?? throw new ArgumentNullException(nameof(loggerFactory));
+        _engineLogger = engineLogger ?? throw new ArgumentNullException(nameof(engineLogger));
+        _clock = clock ?? (() => DateTime.UtcNow);
+        _scriptTimeout = scriptTimeout ?? TimedScriptEvaluator<AlarmPredicateContext, bool>.DefaultTimeout;
+    }
+
+    /// <summary>Raised for every emission the Part9StateMachine produces that the engine should publish.</summary>
+    public event EventHandler<ScriptedAlarmEvent>? OnEvent;
+
+    public IReadOnlyCollection<string> LoadedAlarmIds => _alarms.Keys;
+
+    /// <summary>
+    ///     Load a batch of alarm definitions. Compiles every predicate, aggregates any
+    ///     compile failures into one <see cref="InvalidOperationException"/>, subscribes
+    ///     to upstream input tags, seeds the value cache, loads persisted state from
+    ///     the store (falling back to Fresh for first-load alarms), and recomputes
+    ///     ActiveState per Phase 7 plan decision #14 (startup recovery).
+    /// </summary>
+    public async Task LoadAsync(IReadOnlyList<ScriptedAlarmDefinition> definitions, CancellationToken ct)
+    {
+        if (_disposed) throw new ObjectDisposedException(nameof(ScriptedAlarmEngine));
+        if (definitions is null) throw new ArgumentNullException(nameof(definitions));
+
+        await _evalGate.WaitAsync(ct).ConfigureAwait(false);
+        try
+        {
+            UnsubscribeFromUpstream();
+            _alarms.Clear();
+            _alarmsReferencing.Clear();
+
+            var compileFailures = new List<string>();
+            foreach (var def in definitions)
+            {
+                try
+                {
+                    var extraction = DependencyExtractor.Extract(def.PredicateScriptSource);
+                    if (!extraction.IsValid)
+                    {
+                        var joined = string.Join("; ", extraction.Rejections.Select(r => r.Message));
+                        compileFailures.Add($"{def.AlarmId}: dependency extraction rejected — {joined}");
+                        continue;
+                    }
+
+                    var evaluator = ScriptEvaluator<AlarmPredicateContext, bool>.Compile(def.PredicateScriptSource);
+                    var timed = new TimedScriptEvaluator<AlarmPredicateContext, bool>(evaluator, _scriptTimeout);
+                    var logger = _loggerFactory.Create(def.AlarmId);
+
+                    var templateTokens = MessageTemplate.ExtractTokenPaths(def.MessageTemplate);
+                    var allInputs = new HashSet<string>(extraction.Reads, StringComparer.Ordinal);
+                    foreach (var t in templateTokens) allInputs.Add(t);
+
+                    _alarms[def.AlarmId] = new AlarmState(def, timed, extraction.Reads, templateTokens, logger,
+                        AlarmConditionState.Fresh(def.AlarmId, _clock()));
+
+                    foreach (var path in allInputs)
+                    {
+                        if (!_alarmsReferencing.TryGetValue(path, out var set))
+                            _alarmsReferencing[path] = set = new HashSet<string>(StringComparer.Ordinal);
+                        set.Add(def.AlarmId);
+                    }
+                }
+                catch (Exception ex)
+                {
+                    compileFailures.Add($"{def.AlarmId}: {ex.Message}");
+                }
+            }
+
+            if (compileFailures.Count > 0)
+            {
+                throw new InvalidOperationException(
+                    $"ScriptedAlarmEngine load failed. {compileFailures.Count} alarm(s) did not compile:\n  "
+                    + string.Join("\n  ", compileFailures));
+            }
+
+            // Seed the value cache with current upstream values + subscribe for changes.
+            foreach (var path in _alarmsReferencing.Keys)
+            {
+                _valueCache[path] = _upstream.ReadTag(path);
+                _upstreamSubscriptions.Add(_upstream.SubscribeTag(path, OnUpstreamChange));
+            }
+
+            // Restore persisted state, falling back to Fresh where nothing was saved,
+            // then re-derive ActiveState from the current predicate per decision #14.
+            foreach (var (alarmId, state) in _alarms)
+            {
+                var persisted = await _store.LoadAsync(alarmId, ct).ConfigureAwait(false);
+                var seed = persisted ?? state.Condition;
+                var afterPredicate = await EvaluatePredicateToStateAsync(state, seed, nowUtc: _clock(), ct)
+                    .ConfigureAwait(false);
+                _alarms[alarmId] = state with { Condition = afterPredicate };
+                await _store.SaveAsync(afterPredicate, ct).ConfigureAwait(false);
+            }
+
+            _loaded = true;
+            _engineLogger.Information("ScriptedAlarmEngine loaded {Count} alarm(s)", _alarms.Count);
+
+            // Start the shelving-check timer — ticks every 5s, expires any timed shelves
+            // that have passed their UnshelveAtUtc.
+            _shelvingTimer = new Timer(_ => RunShelvingCheck(),
+                null, TimeSpan.FromSeconds(5), TimeSpan.FromSeconds(5));
+        }
+        finally
+        {
+            _evalGate.Release();
+        }
+    }
+
+    /// <summary>
+    ///     Current persisted state for <paramref name="alarmId"/>. Returns null for
+    ///     unknown alarm. Mainly used for diagnostics + the Admin UI status page.
+    /// </summary>
+    public AlarmConditionState? GetState(string alarmId)
+        => _alarms.TryGetValue(alarmId, out var s) ? s.Condition : null;
+
+    public IReadOnlyCollection<AlarmConditionState> GetAllStates()
+        => _alarms.Values.Select(a => a.Condition).ToArray();
+
+    public Task AcknowledgeAsync(string alarmId, string user, string? comment, CancellationToken ct)
+        => ApplyAsync(alarmId, ct, cur => Part9StateMachine.ApplyAcknowledge(cur, user, comment, _clock()));
+
+    public Task ConfirmAsync(string alarmId, string user, string? comment, CancellationToken ct)
+        => ApplyAsync(alarmId, ct, cur => Part9StateMachine.ApplyConfirm(cur, user, comment, _clock()));
+
+    public Task OneShotShelveAsync(string alarmId, string user, CancellationToken ct)
+        => ApplyAsync(alarmId, ct, cur => Part9StateMachine.ApplyOneShotShelve(cur, user, _clock()));
+
+    public Task TimedShelveAsync(string alarmId, string user, DateTime unshelveAtUtc, CancellationToken ct)
+        => ApplyAsync(alarmId, ct, cur => Part9StateMachine.ApplyTimedShelve(cur, user, unshelveAtUtc, _clock()));
+
+    public Task UnshelveAsync(string alarmId, string user, CancellationToken ct)
+        => ApplyAsync(alarmId, ct, cur => Part9StateMachine.ApplyUnshelve(cur, user, _clock()));
+
+    public Task EnableAsync(string alarmId, string user, CancellationToken ct)
+        => ApplyAsync(alarmId, ct, cur => Part9StateMachine.ApplyEnable(cur, user, _clock()));
+
+    public Task DisableAsync(string alarmId, string user, CancellationToken ct)
+        => ApplyAsync(alarmId, ct, cur => Part9StateMachine.ApplyDisable(cur, user, _clock()));
+
+    public Task AddCommentAsync(string alarmId, string user, string text, CancellationToken ct)
+        => ApplyAsync(alarmId, ct, cur => Part9StateMachine.ApplyAddComment(cur, user, text, _clock()));
+
+    private async Task ApplyAsync(string alarmId, CancellationToken ct, Func<AlarmConditionState, TransitionResult> op)
+    {
+        EnsureLoaded();
+        if (!_alarms.TryGetValue(alarmId, out var state))
+            throw new ArgumentException($"Unknown alarm {alarmId}", nameof(alarmId));
+
+        await _evalGate.WaitAsync(ct).ConfigureAwait(false);
+        try
+        {
+            var result = op(state.Condition);
+            _alarms[alarmId] = state with { Condition = result.State };
+            await _store.SaveAsync(result.State, ct).ConfigureAwait(false);
+            if (result.Emission != EmissionKind.None) EmitEvent(state, result.State, result.Emission);
+        }
+        finally { _evalGate.Release(); }
+    }
+
+    /// <summary>
+    ///     Upstream-change callback. Updates the value cache + enqueues predicate
+    ///     re-evaluation for every alarm referencing the changed path. Fire-and-forget
+    ///     so driver-side dispatch isn't blocked.
+    /// </summary>
+    internal void OnUpstreamChange(string path, DataValueSnapshot value)
+    {
+        _valueCache[path] = value;
+        if (_alarmsReferencing.TryGetValue(path, out var alarmIds))
+        {
+            _ = ReevaluateAsync(alarmIds.ToArray(), CancellationToken.None);
+        }
+    }
+
+    private async Task ReevaluateAsync(IReadOnlyList<string> alarmIds, CancellationToken ct)
+    {
+        try
+        {
+            await _evalGate.WaitAsync(ct).ConfigureAwait(false);
+            try
+            {
+                foreach (var id in alarmIds)
+                {
+                    if (!_alarms.TryGetValue(id, out var state)) continue;
+                    var newState = await EvaluatePredicateToStateAsync(
+                        state, state.Condition, _clock(), ct).ConfigureAwait(false);
+                    if (!ReferenceEquals(newState, state.Condition))
+                    {
+                        _alarms[id] = state with { Condition = newState };
+                        await _store.SaveAsync(newState, ct).ConfigureAwait(false);
+                    }
+                }
+            }
+            finally { _evalGate.Release(); }
+        }
+        catch (Exception ex)
+        {
+            _engineLogger.Error(ex, "ScriptedAlarmEngine reevaluate failed");
+        }
+    }
+
+    /// <summary>
+    ///     Evaluate the predicate + apply the resulting state-machine transition.
+    ///     Returns the new condition state. Emits the appropriate event if the
+    ///     transition produces one.
+    /// </summary>
+    private async Task<AlarmConditionState> EvaluatePredicateToStateAsync(
+        AlarmState state, AlarmConditionState seed, DateTime nowUtc, CancellationToken ct)
+    {
+        var inputs = BuildReadCache(state.Inputs);
+        var context = new AlarmPredicateContext(inputs, state.Logger, _clock);
+
+        bool predicateTrue;
+        try
+        {
+            predicateTrue = await state.Evaluator.RunAsync(context, ct).ConfigureAwait(false);
+        }
+        catch (OperationCanceledException)
+        {
+            throw;
+        }
+        catch (ScriptTimeoutException tex)
+        {
+            state.Logger.Warning("Alarm predicate timed out after {Timeout} — state unchanged", tex.Timeout);
+            return seed;
+        }
+        catch (Exception ex)
+        {
+            state.Logger.Error(ex, "Alarm predicate threw — state unchanged");
+            return seed;
+        }
+
+        var result = Part9StateMachine.ApplyPredicate(seed, predicateTrue, nowUtc);
+        if (result.Emission != EmissionKind.None)
+            EmitEvent(state, result.State, result.Emission);
+        return result.State;
+    }
+
+    private IReadOnlyDictionary<string, DataValueSnapshot> BuildReadCache(IReadOnlySet<string> inputs)
+    {
+        var d = new Dictionary<string, DataValueSnapshot>(StringComparer.Ordinal);
+        foreach (var p in inputs)
+            d[p] = _valueCache.TryGetValue(p, out var v) ? v : _upstream.ReadTag(p);
+        return d;
+    }
+
+    private void EmitEvent(AlarmState state, AlarmConditionState condition, EmissionKind kind)
+    {
+        // Suppressed kind means shelving ate the emission — we don't fire for subscribers
+        // but the state record still advanced so startup recovery reflects reality.
+        if (kind == EmissionKind.Suppressed || kind == EmissionKind.None) return;
+
+        var message = MessageTemplate.Resolve(state.Definition.MessageTemplate, TryLookup);
+        var evt = new ScriptedAlarmEvent(
+            AlarmId: state.Definition.AlarmId,
+            EquipmentPath: state.Definition.EquipmentPath,
+            AlarmName: state.Definition.AlarmName,
+            Kind: state.Definition.Kind,
+            Severity: state.Definition.Severity,
+            Message: message,
+            Condition: condition,
+            Emission: kind,
+            TimestampUtc: _clock());
+        try { OnEvent?.Invoke(this, evt); }
+        catch (Exception ex)
+        {
+            _engineLogger.Warning(ex, "ScriptedAlarmEngine OnEvent subscriber threw for {AlarmId}", state.Definition.AlarmId);
+        }
+    }
+
+    private DataValueSnapshot? TryLookup(string path)
+        => _valueCache.TryGetValue(path, out var v) ? v : null;
+
+    private void RunShelvingCheck()
+    {
+        if (_disposed) return;
+        var ids = _alarms.Keys.ToArray();
+        _ = ShelvingCheckAsync(ids, CancellationToken.None);
+    }
+
+    private async Task ShelvingCheckAsync(IReadOnlyList<string> alarmIds, CancellationToken ct)
+    {
+        try
+        {
+            await _evalGate.WaitAsync(ct).ConfigureAwait(false);
+            try
+            {
+                var now = _clock();
+                foreach (var id in alarmIds)
+                {
+                    if (!_alarms.TryGetValue(id, out var state)) continue;
+                    var result = Part9StateMachine.ApplyShelvingCheck(state.Condition, now);
+                    if (!ReferenceEquals(result.State, state.Condition))
+                    {
+                        _alarms[id] = state with { Condition = result.State };
+                        await _store.SaveAsync(result.State, ct).ConfigureAwait(false);
+                        if (result.Emission != EmissionKind.None)
+                            EmitEvent(state, result.State, result.Emission);
+                    }
+                }
+            }
+            finally { _evalGate.Release(); }
+        }
+        catch (Exception ex)
+        {
+            _engineLogger.Warning(ex, "ScriptedAlarmEngine shelving-check failed");
+        }
+    }
+
+    private void UnsubscribeFromUpstream()
+    {
+        foreach (var s in _upstreamSubscriptions)
+        {
+            try { s.Dispose(); } catch { }
+        }
+        _upstreamSubscriptions.Clear();
+    }
+
+    private void EnsureLoaded()
+    {
+        if (!_loaded) throw new InvalidOperationException(
+            "ScriptedAlarmEngine not loaded. Call LoadAsync first.");
+    }
+
+    public void Dispose()
+    {
+        if (_disposed) return;
+        _disposed = true;
+        _shelvingTimer?.Dispose();
+        UnsubscribeFromUpstream();
+        _alarms.Clear();
+        _alarmsReferencing.Clear();
+    }
+
+    private sealed record AlarmState(
+        ScriptedAlarmDefinition Definition,
+        TimedScriptEvaluator<AlarmPredicateContext, bool> Evaluator,
+        IReadOnlySet<string> Inputs,
+        IReadOnlyList<string> TemplateTokens,
+        ILogger Logger,
+        AlarmConditionState Condition);
+}
+
+/// <summary>
+///     One alarm emission the engine pushed to subscribers. Carries everything
+///     downstream consumers (OPC UA alarm-source adapter + historian sink) need to
+///     publish the event without re-querying the engine.
+/// </summary>
+public sealed record ScriptedAlarmEvent(
+    string AlarmId,
+    string EquipmentPath,
+    string AlarmName,
+    AlarmKind Kind,
+    AlarmSeverity Severity,
+    string Message,
+    AlarmConditionState Condition,
+    EmissionKind Emission,
+    DateTime TimestampUtc);
+
+/// <summary>
+///     Upstream source abstraction — intentionally identical shape to the virtual-tag
+///     engine's so Stream G can compose them behind one driver bridge.
+/// </summary>
+public interface ITagUpstreamSource
+{
+    DataValueSnapshot ReadTag(string path);
+    IDisposable SubscribeTag(string path, Action<string, DataValueSnapshot> observer);
+}

src/ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms/ScriptedAlarmSource.cs

@@ -0,0 +1,122 @@
+using System.Collections.Concurrent;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+
+namespace ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms;
+
+/// <summary>
+///     Adapter that exposes <see cref="ScriptedAlarmEngine"/> through the driver-agnostic
+///     <see cref="IAlarmSource"/> surface. The existing Phase 6.1 <c>AlarmTracker</c>
+///     composition fan-out consumes this alongside Galaxy / AB CIP / FOCAS alarm
+///     sources — no per-source branching in the fan-out.
+/// </summary>
+/// <remarks>
+///     <para>
+///         Per Phase 7 plan Stream C.6, ack / confirm / shelve / unshelve are OPC UA
+///         method calls per-condition. This adapter implements <see cref="AcknowledgeAsync"/>
+///         from the base interface; the richer Part 9 methods (Confirm / Shelve /
+///         Unshelve / AddComment) live directly on the engine, invoked from OPC UA
+///         method handlers wired up in Stream G.
+///     </para>
+///     <para>
+///         SubscribeAlarmsAsync takes a list of source-node-id filters (typically an
+///         Equipment path prefix). When the list is empty every alarm matches. The
+///         adapter doesn't maintain per-subscription state beyond the filter set — it
+///         checks each emission against every live subscription.
+///     </para>
+/// </remarks>
+public sealed class ScriptedAlarmSource : IAlarmSource, IDisposable
+{
+    private readonly ScriptedAlarmEngine _engine;
+    private readonly ConcurrentDictionary<string, Subscription> _subscriptions
+        = new(StringComparer.Ordinal);
+    private bool _disposed;
+
+    public ScriptedAlarmSource(ScriptedAlarmEngine engine)
+    {
+        _engine = engine ?? throw new ArgumentNullException(nameof(engine));
+        _engine.OnEvent += OnEngineEvent;
+    }
+
+    public event EventHandler<AlarmEventArgs>? OnAlarmEvent;
+
+    public Task<IAlarmSubscriptionHandle> SubscribeAlarmsAsync(
+        IReadOnlyList<string> sourceNodeIds, CancellationToken cancellationToken)
+    {
+        if (sourceNodeIds is null) throw new ArgumentNullException(nameof(sourceNodeIds));
+        var handle = new SubscriptionHandle(Guid.NewGuid().ToString("N"));
+        _subscriptions[handle.DiagnosticId] = new Subscription(handle,
+            new HashSet<string>(sourceNodeIds, StringComparer.Ordinal));
+        return Task.FromResult<IAlarmSubscriptionHandle>(handle);
+    }
+
+    public Task UnsubscribeAlarmsAsync(IAlarmSubscriptionHandle handle, CancellationToken cancellationToken)
+    {
+        if (handle is null) throw new ArgumentNullException(nameof(handle));
+        _subscriptions.TryRemove(handle.DiagnosticId, out _);
+        return Task.CompletedTask;
+    }
+
+    public async Task AcknowledgeAsync(
+        IReadOnlyList<AlarmAcknowledgeRequest> acknowledgements, CancellationToken cancellationToken)
+    {
+        if (acknowledgements is null) throw new ArgumentNullException(nameof(acknowledgements));
+        foreach (var a in acknowledgements)
+        {
+            // The base interface doesn't carry a user identity — Stream G provides the
+            // authenticated principal at the OPC UA dispatch layer + proxies through
+            // the engine's richer AcknowledgeAsync. Here we default to "opcua-client"
+            // so callers using the raw IAlarmSource still produce an audit entry.
+            await _engine.AcknowledgeAsync(a.ConditionId, "opcua-client", a.Comment, cancellationToken)
+                .ConfigureAwait(false);
+        }
+    }
+
+    private void OnEngineEvent(object? sender, ScriptedAlarmEvent evt)
+    {
+        if (_disposed) return;
+
+        foreach (var sub in _subscriptions.Values)
+        {
+            if (!Matches(sub, evt)) continue;
+            var payload = new AlarmEventArgs(
+                SubscriptionHandle: sub.Handle,
+                SourceNodeId: evt.EquipmentPath,
+                ConditionId: evt.AlarmId,
+                AlarmType: evt.Kind.ToString(),
+                Message: evt.Message,
+                Severity: evt.Severity,
+                SourceTimestampUtc: evt.TimestampUtc);
+            try { OnAlarmEvent?.Invoke(this, payload); }
+            catch { /* subscriber exceptions don't crash the adapter */ }
+        }
+    }
+
+    private static bool Matches(Subscription sub, ScriptedAlarmEvent evt)
+    {
+        if (sub.Filter.Count == 0) return true;
+        // A subscription matches if any filter is a prefix of the alarm's equipment
+        // path — typical use is "Enterprise/Site/Area/Line" filtering a whole line.
+        foreach (var f in sub.Filter)
+        {
+            if (evt.EquipmentPath.Equals(f, StringComparison.Ordinal)) return true;
+            if (evt.EquipmentPath.StartsWith(f + "/", StringComparison.Ordinal)) return true;
+        }
+        return false;
+    }
+
+    public void Dispose()
+    {
+        if (_disposed) return;
+        _disposed = true;
+        _engine.OnEvent -= OnEngineEvent;
+        _subscriptions.Clear();
+    }
+
+    private sealed class SubscriptionHandle : IAlarmSubscriptionHandle
+    {
+        public SubscriptionHandle(string id) { DiagnosticId = id; }
+        public string DiagnosticId { get; }
+    }
+
+    private sealed record Subscription(SubscriptionHandle Handle, IReadOnlySet<string> Filter);
+}

src/ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms/ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms.csproj

@@ -0,0 +1,32 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <TargetFramework>net10.0</TargetFramework>
+        <Nullable>enable</Nullable>
+        <ImplicitUsings>enable</ImplicitUsings>
+        <LangVersion>latest</LangVersion>
+        <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+        <GenerateDocumentationFile>true</GenerateDocumentationFile>
+        <NoWarn>$(NoWarn);CS1591</NoWarn>
+        <RootNamespace>ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms</RootNamespace>
+    </PropertyGroup>
+
+    <ItemGroup>
+        <PackageReference Include="Serilog" Version="4.2.0"/>
+    </ItemGroup>
+
+    <ItemGroup>
+        <ProjectReference Include="..\ZB.MOM.WW.OtOpcUa.Core.Abstractions\ZB.MOM.WW.OtOpcUa.Core.Abstractions.csproj"/>
+        <ProjectReference Include="..\ZB.MOM.WW.OtOpcUa.Core.Scripting\ZB.MOM.WW.OtOpcUa.Core.Scripting.csproj"/>
+    </ItemGroup>
+
+    <ItemGroup>
+        <InternalsVisibleTo Include="ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms.Tests"/>
+    </ItemGroup>
+
+    <ItemGroup>
+        <NuGetAuditSuppress Include="https://github.com/advisories/GHSA-37gx-xxp4-5rgx"/>
+        <NuGetAuditSuppress Include="https://github.com/advisories/GHSA-w3x6-4m5h-cxqf"/>
+    </ItemGroup>
+
+</Project>

src/ZB.MOM.WW.OtOpcUa.Core/OpcUa/EquipmentNodeWalker.cs

@@ -87,6 +87,16 @@ public static class EquipmentNodeWalker
             .GroupBy(t => t.EquipmentId!, StringComparer.OrdinalIgnoreCase)
             .ToDictionary(g => g.Key, g => g.OrderBy(t => t.Name, StringComparer.Ordinal).ToList(), StringComparer.OrdinalIgnoreCase);
 
+        var virtualTagsByEquipment = (content.VirtualTags ?? [])
+            .Where(v => v.Enabled)
+            .GroupBy(v => v.EquipmentId, StringComparer.OrdinalIgnoreCase)
+            .ToDictionary(g => g.Key, g => g.OrderBy(v => v.Name, StringComparer.Ordinal).ToList(), StringComparer.OrdinalIgnoreCase);
+
+        var scriptedAlarmsByEquipment = (content.ScriptedAlarms ?? [])
+            .Where(a => a.Enabled)
+            .GroupBy(a => a.EquipmentId, StringComparer.OrdinalIgnoreCase)
+            .ToDictionary(g => g.Key, g => g.OrderBy(a => a.Name, StringComparer.Ordinal).ToList(), StringComparer.OrdinalIgnoreCase);
+
         foreach (var area in content.Areas.OrderBy(a => a.Name, StringComparer.Ordinal))
         {
             var areaBuilder = namespaceBuilder.Folder(area.Name, area.Name);
@@ -103,9 +113,17 @@ public static class EquipmentNodeWalker
                     AddIdentifierProperties(equipmentBuilder, equipment);
                     IdentificationFolderBuilder.Build(equipmentBuilder, equipment);
 
-                    if (!tagsByEquipment.TryGetValue(equipment.EquipmentId, out var equipmentTags)) continue;
-                    foreach (var tag in equipmentTags)
-                        AddTagVariable(equipmentBuilder, tag);
+                    if (tagsByEquipment.TryGetValue(equipment.EquipmentId, out var equipmentTags))
+                        foreach (var tag in equipmentTags)
+                            AddTagVariable(equipmentBuilder, tag);
+
+                    if (virtualTagsByEquipment.TryGetValue(equipment.EquipmentId, out var vTags))
+                        foreach (var vtag in vTags)
+                            AddVirtualTagVariable(equipmentBuilder, vtag);
+
+                    if (scriptedAlarmsByEquipment.TryGetValue(equipment.EquipmentId, out var alarms))
+                        foreach (var alarm in alarms)
+                            AddScriptedAlarmVariable(equipmentBuilder, alarm);
                 }
             }
         }
@@ -157,6 +175,55 @@ public static class EquipmentNodeWalker
     /// </summary>
     private static DriverDataType ParseDriverDataType(string raw) =>
         Enum.TryParse<DriverDataType>(raw, ignoreCase: true, out var parsed) ? parsed : DriverDataType.String;
+
+    /// <summary>
+    ///     Emit a <see cref="VirtualTag"/> row as a <see cref="NodeSourceKind.Virtual"/>
+    ///     variable node. <c>FullName</c> doubles as the UNS path Phase 7's VirtualTagEngine
+    ///     addresses its engine-side entries by. The <c>VirtualTagId</c> discriminator lets
+    ///     the DriverNodeManager dispatch Reads/Subscribes to the engine rather than any
+    ///     driver.
+    /// </summary>
+    private static void AddVirtualTagVariable(IAddressSpaceBuilder equipmentBuilder, VirtualTag vtag)
+    {
+        var attr = new DriverAttributeInfo(
+            FullName: vtag.VirtualTagId,
+            DriverDataType: ParseDriverDataType(vtag.DataType),
+            IsArray: false,
+            ArrayDim: null,
+            SecurityClass: SecurityClassification.FreeAccess,
+            IsHistorized: vtag.Historize,
+            IsAlarm: false,
+            WriteIdempotent: false,
+            Source: NodeSourceKind.Virtual,
+            VirtualTagId: vtag.VirtualTagId,
+            ScriptedAlarmId: null);
+        equipmentBuilder.Variable(vtag.Name, vtag.Name, attr);
+    }
+
+    /// <summary>
+    ///     Emit a <see cref="ScriptedAlarm"/> row as a <see cref="NodeSourceKind.ScriptedAlarm"/>
+    ///     variable node. The OPC UA Part 9 alarm-condition materialization happens at the
+    ///     node-manager level (which wires the concrete <c>AlarmConditionState</c> subclass
+    ///     per <see cref="ScriptedAlarm.AlarmType"/>); this walker provides the browse-level
+    ///     anchor + the <see cref="DriverAttributeInfo.IsAlarm"/> flag that triggers that
+    ///     materialization path.
+    /// </summary>
+    private static void AddScriptedAlarmVariable(IAddressSpaceBuilder equipmentBuilder, ScriptedAlarm alarm)
+    {
+        var attr = new DriverAttributeInfo(
+            FullName: alarm.ScriptedAlarmId,
+            DriverDataType: DriverDataType.Boolean,
+            IsArray: false,
+            ArrayDim: null,
+            SecurityClass: SecurityClassification.FreeAccess,
+            IsHistorized: false,
+            IsAlarm: true,
+            WriteIdempotent: false,
+            Source: NodeSourceKind.ScriptedAlarm,
+            VirtualTagId: null,
+            ScriptedAlarmId: alarm.ScriptedAlarmId);
+        equipmentBuilder.Variable(alarm.Name, alarm.Name, attr);
+    }
 }
 
 /// <summary>
@@ -170,4 +237,6 @@ public sealed record EquipmentNamespaceContent(
     IReadOnlyList<UnsArea> Areas,
     IReadOnlyList<UnsLine> Lines,
     IReadOnlyList<Equipment> Equipment,
-    IReadOnlyList<Tag> Tags);
+    IReadOnlyList<Tag> Tags,
+    IReadOnlyList<VirtualTag>? VirtualTags = null,
+    IReadOnlyList<ScriptedAlarm>? ScriptedAlarms = null);

src/ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Shared/Contracts/Framing.cs

@@ -60,6 +60,14 @@ public enum MessageKind : byte
     HostConnectivityStatus     = 0x70,
     RuntimeStatusChange        = 0x71,
 
+    // Phase 7 Stream D — historian alarm sink. Main server → Galaxy.Host batched
+    // writes into the Aveva Historian alarm schema via the already-loaded
+    // aahClientManaged DLLs. HistorianConnectivityStatus fires proactively from the
+    // Host when the SDK session transitions so diagnostics flip promptly.
+    HistorianAlarmEventRequest        = 0x80,
+    HistorianAlarmEventResponse       = 0x81,
+    HistorianConnectivityStatus       = 0x82,
+
     RecycleHostRequest         = 0xF0,
     RecycleStatusResponse      = 0xF1,
 

src/ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Shared/Contracts/HistorianAlarms.cs

@@ -0,0 +1,92 @@
+using System;
+using MessagePack;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Shared.Contracts;
+
+/// <summary>
+///     Phase 7 Stream D — IPC contracts for routing Part 9 alarm transitions from the
+///     main .NET 10 server into Galaxy.Host's already-loaded <c>aahClientManaged</c>
+///     DLLs. Reuses the Tier-C isolation + licensing pathway rather than loading 32-bit
+///     native historian code into the main server.
+/// </summary>
+/// <remarks>
+///     <para>
+///         Batched on the wire to amortize IPC overhead — the main server's SqliteStoreAndForwardSink
+///         ships up to 100 events per request per Phase 7 plan Stream D.5.
+///     </para>
+///     <para>
+///         Per-event outcomes (Ack / RetryPlease / PermanentFail) let the drain worker
+///         dead-letter malformed events without blocking neighbors in the batch.
+///         <see cref="HistorianConnectivityStatusNotification"/> fires proactively from
+///         the Host when the SDK session drops so the /hosts + /alarms/historian Admin
+///         diagnostics pages flip to red promptly instead of waiting for the next
+///         drain cycle.
+///     </para>
+/// </remarks>
+[MessagePackObject]
+public sealed class HistorianAlarmEventRequest
+{
+    [Key(0)] public HistorianAlarmEventDto[] Events { get; set; } = Array.Empty<HistorianAlarmEventDto>();
+}
+
+[MessagePackObject]
+public sealed class HistorianAlarmEventResponse
+{
+    /// <summary>Per-event outcome, same order as the request.</summary>
+    [Key(0)] public HistorianAlarmEventOutcomeDto[] Outcomes { get; set; } = Array.Empty<HistorianAlarmEventOutcomeDto>();
+}
+
+/// <summary>Outcome enum — bytes on the wire so it stays compact.</summary>
+public enum HistorianAlarmEventOutcomeDto : byte
+{
+    /// <summary>Successfully persisted to the historian — remove from queue.</summary>
+    Ack = 0,
+    /// <summary>Transient failure (historian disconnected, timeout, busy) — retry after backoff.</summary>
+    RetryPlease = 1,
+    /// <summary>Permanent failure (malformed, unrecoverable SDK error) — move to dead-letter.</summary>
+    PermanentFail = 2,
+}
+
+/// <summary>One alarm-transition payload. Fields mirror <c>Core.AlarmHistorian.AlarmHistorianEvent</c>.</summary>
+[MessagePackObject]
+public sealed class HistorianAlarmEventDto
+{
+    [Key(0)] public string AlarmId { get; set; } = string.Empty;
+    [Key(1)] public string EquipmentPath { get; set; } = string.Empty;
+    [Key(2)] public string AlarmName { get; set; } = string.Empty;
+
+    /// <summary>Concrete Part 9 subtype name — "LimitAlarm" / "OffNormalAlarm" / "AlarmCondition" / "DiscreteAlarm".</summary>
+    [Key(3)] public string AlarmTypeName { get; set; } = string.Empty;
+
+    /// <summary>Numeric severity the Host maps to the historian's priority scale.</summary>
+    [Key(4)] public int Severity { get; set; }
+
+    /// <summary>Which transition this event represents — "Activated" / "Cleared" / "Acknowledged" / etc.</summary>
+    [Key(5)] public string EventKind { get; set; } = string.Empty;
+
+    /// <summary>Pre-rendered message — template tokens resolved upstream.</summary>
+    [Key(6)] public string Message { get; set; } = string.Empty;
+
+    /// <summary>Operator who triggered the transition. "system" for engine-driven events.</summary>
+    [Key(7)] public string User { get; set; } = "system";
+
+    /// <summary>Operator-supplied free-form comment, if any.</summary>
+    [Key(8)] public string? Comment { get; set; }
+
+    /// <summary>Source timestamp (UTC Unix milliseconds).</summary>
+    [Key(9)] public long TimestampUtcUnixMs { get; set; }
+}
+
+/// <summary>
+///     Proactive notification — Galaxy.Host pushes this when the historian SDK session
+///     transitions (connected / disconnected / degraded). The main server reflects this
+///     into the historian sink status so Admin UI surfaces the problem without the
+///     operator having to scrutinize drain cadence.
+/// </summary>
+[MessagePackObject]
+public sealed class HistorianConnectivityStatusNotification
+{
+    [Key(0)] public string Status { get; set; } = "unknown"; // connected | disconnected | degraded
+    [Key(1)] public string? Detail { get; set; }
+    [Key(2)] public long ObservedAtUtcUnixMs { get; set; }
+}

tests/ZB.MOM.WW.OtOpcUa.Admin.Tests/Phase7ServicesTests.cs

@@ -0,0 +1,196 @@
+using Microsoft.EntityFrameworkCore;
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Admin.Services;
+using ZB.MOM.WW.OtOpcUa.Configuration;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+using ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian;
+
+namespace ZB.MOM.WW.OtOpcUa.Admin.Tests;
+
+/// <summary>
+///     Admin-side services shipped in Phase 7 Stream F — draft CRUD for scripts + virtual
+///     tags + scripted alarms, the pre-publish test harness, and the historian
+///     diagnostics façade.
+/// </summary>
+[Trait("Category", "Unit")]
+public sealed class Phase7ServicesTests
+{
+    private static OtOpcUaConfigDbContext NewDb([System.Runtime.CompilerServices.CallerMemberName] string test = "")
+    {
+        var options = new DbContextOptionsBuilder<OtOpcUaConfigDbContext>()
+            .UseInMemoryDatabase($"phase7-{test}-{Guid.NewGuid():N}")
+            .Options;
+        return new OtOpcUaConfigDbContext(options);
+    }
+
+    [Fact]
+    public async Task ScriptService_AddAsync_generates_logical_id_and_hash()
+    {
+        using var db = NewDb();
+        var svc = new ScriptService(db);
+
+        var s = await svc.AddAsync(5, "line-rate", "return ctx.GetTag(\"a\").Value;", default);
+
+        s.ScriptId.ShouldStartWith("scr-");
+        s.GenerationId.ShouldBe(5);
+        s.SourceHash.Length.ShouldBe(64);
+        (await svc.ListAsync(5, default)).Count.ShouldBe(1);
+    }
+
+    [Fact]
+    public async Task ScriptService_UpdateAsync_recomputes_hash_on_source_change()
+    {
+        using var db = NewDb();
+        var svc = new ScriptService(db);
+        var s = await svc.AddAsync(5, "s", "return 1;", default);
+        var hashBefore = s.SourceHash;
+
+        var updated = await svc.UpdateAsync(5, s.ScriptId, "s", "return 2;", default);
+        updated.SourceHash.ShouldNotBe(hashBefore);
+    }
+
+    [Fact]
+    public async Task ScriptService_UpdateAsync_same_source_same_hash()
+    {
+        using var db = NewDb();
+        var svc = new ScriptService(db);
+        var s = await svc.AddAsync(5, "s", "return 1;", default);
+        var updated = await svc.UpdateAsync(5, s.ScriptId, "renamed", "return 1;", default);
+
+        updated.SourceHash.ShouldBe(s.SourceHash, "source unchanged → hash unchanged → compile cache hit preserved");
+    }
+
+    [Fact]
+    public async Task ScriptService_DeleteAsync_is_idempotent()
+    {
+        using var db = NewDb();
+        var svc = new ScriptService(db);
+
+        await Should.NotThrowAsync(() => svc.DeleteAsync(5, "nonexistent", default));
+    }
+
+    [Fact]
+    public async Task VirtualTagService_round_trips_trigger_flags()
+    {
+        using var db = NewDb();
+        var svc = new VirtualTagService(db);
+
+        var v = await svc.AddAsync(7, "eq-1", "LineRate", "Float32", "scr-1",
+            changeTriggered: true, timerIntervalMs: 1000, historize: true, default);
+
+        v.ChangeTriggered.ShouldBeTrue();
+        v.TimerIntervalMs.ShouldBe(1000);
+        v.Historize.ShouldBeTrue();
+        v.Enabled.ShouldBeTrue();
+        (await svc.ListAsync(7, default)).Single().VirtualTagId.ShouldBe(v.VirtualTagId);
+    }
+
+    [Fact]
+    public async Task VirtualTagService_update_enabled_toggles_flag()
+    {
+        using var db = NewDb();
+        var svc = new VirtualTagService(db);
+        var v = await svc.AddAsync(7, "eq-1", "N", "Int32", "scr-1", true, null, false, default);
+
+        var disabled = await svc.UpdateEnabledAsync(7, v.VirtualTagId, false, default);
+        disabled.Enabled.ShouldBeFalse();
+    }
+
+    [Fact]
+    public async Task ScriptedAlarmService_defaults_HistorizeToAveva_true_per_plan_decision_15()
+    {
+        using var db = NewDb();
+        var svc = new ScriptedAlarmService(db);
+
+        var a = await svc.AddAsync(9, "eq-1", "HighTemp", "LimitAlarm", severity: 800,
+            messageTemplate: "{Temp} too high", predicateScriptId: "scr-9",
+            historizeToAveva: true, retain: true, default);
+
+        a.HistorizeToAveva.ShouldBeTrue();
+        a.Severity.ShouldBe(800);
+        a.ScriptedAlarmId.ShouldStartWith("sal-");
+    }
+
+    [Fact]
+    public async Task ScriptTestHarness_runs_successful_script_and_captures_writes()
+    {
+        var harness = new ScriptTestHarnessService();
+        var source = """
+            ctx.SetVirtualTag("Out", 42);
+            return ctx.GetTag("In").Value;
+            """;
+        var inputs = new Dictionary<string, DataValueSnapshot>
+        {
+            ["In"] = new(123, 0u, DateTime.UtcNow, DateTime.UtcNow),
+        };
+
+        var result = await harness.RunVirtualTagAsync(source, inputs, default);
+
+        result.Outcome.ShouldBe(ScriptTestOutcome.Success);
+        result.Output.ShouldBe(123);
+        result.Writes["Out"].ShouldBe(42);
+    }
+
+    [Fact]
+    public async Task ScriptTestHarness_rejects_missing_synthetic_input()
+    {
+        var harness = new ScriptTestHarnessService();
+        var source = """return ctx.GetTag("A").Value;""";
+
+        var result = await harness.RunVirtualTagAsync(source, new Dictionary<string, DataValueSnapshot>(), default);
+
+        result.Outcome.ShouldBe(ScriptTestOutcome.MissingInputs);
+        result.Errors[0].ShouldContain("A");
+    }
+
+    [Fact]
+    public async Task ScriptTestHarness_rejects_extra_synthetic_input_not_referenced_by_script()
+    {
+        var harness = new ScriptTestHarnessService();
+        var source = """return 1;""";  // no GetTag calls
+        var inputs = new Dictionary<string, DataValueSnapshot>
+        {
+            ["Unexpected"] = new(0, 0u, DateTime.UtcNow, DateTime.UtcNow),
+        };
+
+        var result = await harness.RunVirtualTagAsync(source, inputs, default);
+
+        result.Outcome.ShouldBe(ScriptTestOutcome.UnknownInputs);
+        result.Errors[0].ShouldContain("Unexpected");
+    }
+
+    [Fact]
+    public async Task ScriptTestHarness_rejects_non_literal_path()
+    {
+        var harness = new ScriptTestHarnessService();
+        var source = """
+            var p = "A";
+            return ctx.GetTag(p).Value;
+            """;
+
+        var result = await harness.RunVirtualTagAsync(source, new Dictionary<string, DataValueSnapshot>(), default);
+
+        result.Outcome.ShouldBe(ScriptTestOutcome.DependencyRejected);
+        result.Errors.ShouldNotBeEmpty();
+    }
+
+    [Fact]
+    public async Task ScriptTestHarness_surfaces_compile_error_as_Threw()
+    {
+        var harness = new ScriptTestHarnessService();
+        var source = "this is not valid C#;";
+
+        var result = await harness.RunVirtualTagAsync(source, new Dictionary<string, DataValueSnapshot>(), default);
+
+        result.Outcome.ShouldBe(ScriptTestOutcome.Threw);
+    }
+
+    [Fact]
+    public void HistorianDiagnosticsService_reports_Disabled_for_null_sink()
+    {
+        var diag = new HistorianDiagnosticsService(NullAlarmHistorianSink.Instance);
+        diag.GetStatus().DrainState.ShouldBe(HistorianDrainState.Disabled);
+        diag.TryRetryDeadLettered().ShouldBe(0);
+    }
+}

tests/ZB.MOM.WW.OtOpcUa.Configuration.Tests/Phase7ScriptingEntitiesTests.cs

@@ -0,0 +1,184 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Metadata;
+using Microsoft.Extensions.DependencyInjection;
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Configuration.Entities;
+
+namespace ZB.MOM.WW.OtOpcUa.Configuration.Tests;
+
+/// <summary>
+///     Verifies the Phase 7 Stream E entities (<see cref="Script"/>, <see cref="VirtualTag"/>,
+///     <see cref="ScriptedAlarm"/>, <see cref="ScriptedAlarmState"/>) register correctly in
+///     the EF model, map to the expected tables/columns/indexes, and carry the check constraints
+///     the plan decisions call for. Introspection only — no SQL Server required.
+/// </summary>
+[Trait("Category", "Unit")]
+public sealed class Phase7ScriptingEntitiesTests
+{
+    private static OtOpcUaConfigDbContext BuildCtx()
+    {
+        var options = new DbContextOptionsBuilder<OtOpcUaConfigDbContext>()
+            .UseSqlServer("Server=(local);Database=dummy;Integrated Security=true") // not connected
+            .Options;
+        return new OtOpcUaConfigDbContext(options);
+    }
+
+    private static Microsoft.EntityFrameworkCore.Metadata.IModel DesignModel(OtOpcUaConfigDbContext ctx)
+        => ctx.GetService<IDesignTimeModel>().Model;
+
+    [Fact]
+    public void Script_entity_registered_with_expected_table_and_columns()
+    {
+        using var ctx = BuildCtx();
+        var entity = ctx.Model.FindEntityType(typeof(Script)).ShouldNotBeNull();
+
+        entity.GetTableName().ShouldBe("Script");
+        entity.FindProperty(nameof(Script.ScriptRowId)).ShouldNotBeNull();
+        entity.FindProperty(nameof(Script.ScriptId)).ShouldNotBeNull()
+            .GetMaxLength().ShouldBe(64);
+        entity.FindProperty(nameof(Script.SourceCode)).ShouldNotBeNull()
+            .GetColumnType().ShouldBe("nvarchar(max)");
+        entity.FindProperty(nameof(Script.SourceHash)).ShouldNotBeNull()
+            .GetMaxLength().ShouldBe(64);
+        entity.FindProperty(nameof(Script.Language)).ShouldNotBeNull()
+            .GetMaxLength().ShouldBe(16);
+    }
+
+    [Fact]
+    public void Script_has_unique_logical_id_per_generation()
+    {
+        using var ctx = BuildCtx();
+        var entity = ctx.Model.FindEntityType(typeof(Script)).ShouldNotBeNull();
+        entity.GetIndexes().ShouldContain(
+            i => i.IsUnique && i.GetDatabaseName() == "UX_Script_Generation_LogicalId");
+        entity.GetIndexes().ShouldContain(
+            i => i.GetDatabaseName() == "IX_Script_Generation_SourceHash");
+    }
+
+    [Fact]
+    public void VirtualTag_entity_registered_with_trigger_check_constraint()
+    {
+        using var ctx = BuildCtx();
+        var entity = DesignModel(ctx).FindEntityType(typeof(VirtualTag)).ShouldNotBeNull();
+        entity.GetTableName().ShouldBe("VirtualTag");
+
+        var checks = entity.GetCheckConstraints().Select(c => c.Name).ToArray();
+        checks.ShouldContain("CK_VirtualTag_Trigger_AtLeastOne");
+        checks.ShouldContain("CK_VirtualTag_TimerInterval_Min");
+    }
+
+    [Fact]
+    public void VirtualTag_enforces_unique_name_per_Equipment()
+    {
+        using var ctx = BuildCtx();
+        var entity = ctx.Model.FindEntityType(typeof(VirtualTag)).ShouldNotBeNull();
+        entity.GetIndexes().ShouldContain(
+            i => i.IsUnique && i.GetDatabaseName() == "UX_VirtualTag_Generation_EquipmentPath");
+    }
+
+    [Fact]
+    public void VirtualTag_has_ChangeTriggered_and_Historize_flags()
+    {
+        using var ctx = BuildCtx();
+        var entity = ctx.Model.FindEntityType(typeof(VirtualTag)).ShouldNotBeNull();
+        entity.FindProperty(nameof(VirtualTag.ChangeTriggered)).ShouldNotBeNull()
+            .ClrType.ShouldBe(typeof(bool));
+        entity.FindProperty(nameof(VirtualTag.Historize)).ShouldNotBeNull()
+            .ClrType.ShouldBe(typeof(bool));
+        entity.FindProperty(nameof(VirtualTag.TimerIntervalMs)).ShouldNotBeNull()
+            .ClrType.ShouldBe(typeof(int?));
+    }
+
+    [Fact]
+    public void ScriptedAlarm_entity_registered_with_severity_and_type_checks()
+    {
+        using var ctx = BuildCtx();
+        var entity = DesignModel(ctx).FindEntityType(typeof(ScriptedAlarm)).ShouldNotBeNull();
+        entity.GetTableName().ShouldBe("ScriptedAlarm");
+
+        var checks = entity.GetCheckConstraints().Select(c => c.Name).ToArray();
+        checks.ShouldContain("CK_ScriptedAlarm_Severity_Range");
+        checks.ShouldContain("CK_ScriptedAlarm_AlarmType");
+    }
+
+    [Fact]
+    public void ScriptedAlarm_has_HistorizeToAveva_default_true_per_plan_decision_15()
+    {
+        // Defaults live on the CLR default assignment — verify the initializer.
+        var alarm = new ScriptedAlarm
+        {
+            ScriptedAlarmId = "a1",
+            EquipmentId = "eq1",
+            Name = "n",
+            AlarmType = "LimitAlarm",
+            MessageTemplate = "m",
+            PredicateScriptId = "s1",
+        };
+        alarm.HistorizeToAveva.ShouldBeTrue();
+        alarm.Retain.ShouldBeTrue();
+        alarm.Severity.ShouldBe(500);
+        alarm.Enabled.ShouldBeTrue();
+    }
+
+    [Fact]
+    public void ScriptedAlarmState_keyed_on_ScriptedAlarmId_not_generation_scoped()
+    {
+        using var ctx = BuildCtx();
+        var entity = ctx.Model.FindEntityType(typeof(ScriptedAlarmState)).ShouldNotBeNull();
+        entity.GetTableName().ShouldBe("ScriptedAlarmState");
+
+        var pk = entity.FindPrimaryKey().ShouldNotBeNull();
+        pk.Properties.Count.ShouldBe(1);
+        pk.Properties[0].Name.ShouldBe(nameof(ScriptedAlarmState.ScriptedAlarmId));
+
+        // State is NOT generation-scoped — GenerationId column should not exist per plan decision #14.
+        entity.FindProperty("GenerationId").ShouldBeNull(
+            "ack state follows alarm identity across generations");
+    }
+
+    [Fact]
+    public void ScriptedAlarmState_default_state_values_match_Part9_initial_states()
+    {
+        var state = new ScriptedAlarmState
+        {
+            ScriptedAlarmId = "a1",
+            EnabledState = "Enabled",
+            AckedState = "Unacknowledged",
+            ConfirmedState = "Unconfirmed",
+            ShelvingState = "Unshelved",
+        };
+        state.CommentsJson.ShouldBe("[]");
+        state.LastAckUser.ShouldBeNull();
+        state.LastAckUtc.ShouldBeNull();
+    }
+
+    [Fact]
+    public void ScriptedAlarmState_has_JSON_check_constraint_on_CommentsJson()
+    {
+        using var ctx = BuildCtx();
+        var entity = DesignModel(ctx).FindEntityType(typeof(ScriptedAlarmState)).ShouldNotBeNull();
+        var checks = entity.GetCheckConstraints().Select(c => c.Name).ToArray();
+        checks.ShouldContain("CK_ScriptedAlarmState_CommentsJson_IsJson");
+    }
+
+    [Fact]
+    public void All_new_entities_exposed_via_DbSet()
+    {
+        using var ctx = BuildCtx();
+        ctx.Scripts.ShouldNotBeNull();
+        ctx.VirtualTags.ShouldNotBeNull();
+        ctx.ScriptedAlarms.ShouldNotBeNull();
+        ctx.ScriptedAlarmStates.ShouldNotBeNull();
+    }
+
+    [Fact]
+    public void AddPhase7ScriptingTables_migration_exists_in_assembly()
+    {
+        // The migration type carries the design-time snapshot + Up/Down methods EF uses to
+        // apply the schema. Missing = schema won't roll forward in deployments.
+        var t = typeof(Migrations.AddPhase7ScriptingTables);
+        t.ShouldNotBeNull();
+    }
+}

tests/ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian.Tests/SqliteStoreAndForwardSinkTests.cs

@@ -0,0 +1,286 @@
+using Serilog;
+using Serilog.Core;
+using Serilog.Events;
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+
+namespace ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian.Tests;
+
+/// <summary>
+///     Verifies the durable SQLite store-and-forward queue behind the historian sink:
+///     round-trip Ack, backoff ladder on RetryPlease, dead-lettering on PermanentFail,
+///     capacity eviction, and retention-based dead-letter purge.
+/// </summary>
+[Trait("Category", "Unit")]
+public sealed class SqliteStoreAndForwardSinkTests : IDisposable
+{
+    private readonly string _dbPath;
+    private readonly ILogger _log;
+
+    public SqliteStoreAndForwardSinkTests()
+    {
+        _dbPath = Path.Combine(Path.GetTempPath(), $"otopcua-historian-{Guid.NewGuid():N}.sqlite");
+        _log = new LoggerConfiguration().MinimumLevel.Verbose().CreateLogger();
+    }
+
+    public void Dispose()
+    {
+        try { if (File.Exists(_dbPath)) File.Delete(_dbPath); } catch { }
+    }
+
+    private sealed class FakeWriter : IAlarmHistorianWriter
+    {
+        public Queue<HistorianWriteOutcome> NextOutcomePerEvent { get; } = new();
+        public HistorianWriteOutcome DefaultOutcome { get; set; } = HistorianWriteOutcome.Ack;
+        public List<IReadOnlyList<AlarmHistorianEvent>> Batches { get; } = [];
+        public Exception? ThrowOnce { get; set; }
+
+        public Task<IReadOnlyList<HistorianWriteOutcome>> WriteBatchAsync(
+            IReadOnlyList<AlarmHistorianEvent> batch, CancellationToken ct)
+        {
+            if (ThrowOnce is not null)
+            {
+                var e = ThrowOnce;
+                ThrowOnce = null;
+                throw e;
+            }
+            Batches.Add(batch);
+            var outcomes = new List<HistorianWriteOutcome>();
+            for (var i = 0; i < batch.Count; i++)
+                outcomes.Add(NextOutcomePerEvent.Count > 0 ? NextOutcomePerEvent.Dequeue() : DefaultOutcome);
+            return Task.FromResult<IReadOnlyList<HistorianWriteOutcome>>(outcomes);
+        }
+    }
+
+    private static AlarmHistorianEvent Event(string alarmId, DateTime? ts = null) => new(
+        AlarmId: alarmId,
+        EquipmentPath: "/Site/Line1/Cell",
+        AlarmName: "HighTemp",
+        AlarmTypeName: "LimitAlarm",
+        Severity: AlarmSeverity.High,
+        EventKind: "Activated",
+        Message: "temp exceeded",
+        User: "system",
+        Comment: null,
+        TimestampUtc: ts ?? DateTime.UtcNow);
+
+    [Fact]
+    public async Task EnqueueThenDrain_Ack_removes_row()
+    {
+        var writer = new FakeWriter();
+        using var sink = new SqliteStoreAndForwardSink(_dbPath, writer, _log);
+
+        await sink.EnqueueAsync(Event("A1"), CancellationToken.None);
+        sink.GetStatus().QueueDepth.ShouldBe(1);
+
+        await sink.DrainOnceAsync(CancellationToken.None);
+
+        writer.Batches.Count.ShouldBe(1);
+        writer.Batches[0].Count.ShouldBe(1);
+        writer.Batches[0][0].AlarmId.ShouldBe("A1");
+        var status = sink.GetStatus();
+        status.QueueDepth.ShouldBe(0);
+        status.DeadLetterDepth.ShouldBe(0);
+        status.LastSuccessUtc.ShouldNotBeNull();
+    }
+
+    [Fact]
+    public async Task Drain_with_empty_queue_is_noop()
+    {
+        var writer = new FakeWriter();
+        using var sink = new SqliteStoreAndForwardSink(_dbPath, writer, _log);
+
+        await sink.DrainOnceAsync(CancellationToken.None);
+
+        writer.Batches.ShouldBeEmpty();
+        sink.GetStatus().DrainState.ShouldBe(HistorianDrainState.Idle);
+    }
+
+    [Fact]
+    public async Task RetryPlease_bumps_backoff_and_keeps_row()
+    {
+        var writer = new FakeWriter();
+        writer.NextOutcomePerEvent.Enqueue(HistorianWriteOutcome.RetryPlease);
+        using var sink = new SqliteStoreAndForwardSink(_dbPath, writer, _log);
+
+        await sink.EnqueueAsync(Event("A1"), CancellationToken.None);
+        var before = sink.CurrentBackoff;
+        await sink.DrainOnceAsync(CancellationToken.None);
+
+        sink.CurrentBackoff.ShouldBeGreaterThan(before);
+        sink.GetStatus().QueueDepth.ShouldBe(1, "row stays in queue for retry");
+        sink.GetStatus().DrainState.ShouldBe(HistorianDrainState.BackingOff);
+    }
+
+    [Fact]
+    public async Task Ack_after_Retry_resets_backoff()
+    {
+        var writer = new FakeWriter();
+        writer.NextOutcomePerEvent.Enqueue(HistorianWriteOutcome.RetryPlease);
+        using var sink = new SqliteStoreAndForwardSink(_dbPath, writer, _log);
+
+        await sink.EnqueueAsync(Event("A1"), CancellationToken.None);
+        await sink.DrainOnceAsync(CancellationToken.None);
+        sink.CurrentBackoff.ShouldBeGreaterThan(TimeSpan.FromSeconds(1) - TimeSpan.FromMilliseconds(1));
+
+        writer.NextOutcomePerEvent.Enqueue(HistorianWriteOutcome.Ack);
+        await sink.DrainOnceAsync(CancellationToken.None);
+
+        sink.CurrentBackoff.ShouldBe(TimeSpan.FromSeconds(1));
+        sink.GetStatus().QueueDepth.ShouldBe(0);
+    }
+
+    [Fact]
+    public async Task PermanentFail_dead_letters_one_row_only()
+    {
+        var writer = new FakeWriter();
+        writer.NextOutcomePerEvent.Enqueue(HistorianWriteOutcome.PermanentFail);
+        writer.NextOutcomePerEvent.Enqueue(HistorianWriteOutcome.Ack);
+        using var sink = new SqliteStoreAndForwardSink(_dbPath, writer, _log);
+
+        await sink.EnqueueAsync(Event("bad"), CancellationToken.None);
+        await sink.EnqueueAsync(Event("good"), CancellationToken.None);
+        await sink.DrainOnceAsync(CancellationToken.None);
+
+        var status = sink.GetStatus();
+        status.QueueDepth.ShouldBe(0, "good row acked");
+        status.DeadLetterDepth.ShouldBe(1, "bad row dead-lettered");
+    }
+
+    [Fact]
+    public async Task Writer_exception_treated_as_retry_for_whole_batch()
+    {
+        var writer = new FakeWriter { ThrowOnce = new InvalidOperationException("pipe broken") };
+        using var sink = new SqliteStoreAndForwardSink(_dbPath, writer, _log);
+
+        await sink.EnqueueAsync(Event("A1"), CancellationToken.None);
+        await sink.DrainOnceAsync(CancellationToken.None);
+
+        var status = sink.GetStatus();
+        status.QueueDepth.ShouldBe(1);
+        status.LastError.ShouldBe("pipe broken");
+        status.DrainState.ShouldBe(HistorianDrainState.BackingOff);
+
+        // Next drain after the writer recovers should Ack.
+        await sink.DrainOnceAsync(CancellationToken.None);
+        sink.GetStatus().QueueDepth.ShouldBe(0);
+    }
+
+    [Fact]
+    public async Task Capacity_eviction_drops_oldest_nondeadlettered_row()
+    {
+        var writer = new FakeWriter();
+        using var sink = new SqliteStoreAndForwardSink(
+            _dbPath, writer, _log, batchSize: 100, capacity: 3);
+
+        await sink.EnqueueAsync(Event("A1"), CancellationToken.None);
+        await sink.EnqueueAsync(Event("A2"), CancellationToken.None);
+        await sink.EnqueueAsync(Event("A3"), CancellationToken.None);
+        // A4 enqueue must evict the oldest (A1).
+        await sink.EnqueueAsync(Event("A4"), CancellationToken.None);
+
+        sink.GetStatus().QueueDepth.ShouldBe(3);
+
+        await sink.DrainOnceAsync(CancellationToken.None);
+        var drained = writer.Batches[0].Select(e => e.AlarmId).ToArray();
+        drained.ShouldNotContain("A1");
+        drained.ShouldContain("A2");
+        drained.ShouldContain("A3");
+        drained.ShouldContain("A4");
+    }
+
+    [Fact]
+    public async Task Deadlettered_rows_are_purged_past_retention()
+    {
+        var now = new DateTime(2026, 1, 1, 0, 0, 0, DateTimeKind.Utc);
+        DateTime clock = now;
+
+        var writer = new FakeWriter();
+        writer.NextOutcomePerEvent.Enqueue(HistorianWriteOutcome.PermanentFail);
+        using var sink = new SqliteStoreAndForwardSink(
+            _dbPath, writer, _log, deadLetterRetention: TimeSpan.FromDays(30),
+            clock: () => clock);
+
+        await sink.EnqueueAsync(Event("bad"), CancellationToken.None);
+        await sink.DrainOnceAsync(CancellationToken.None);
+        sink.GetStatus().DeadLetterDepth.ShouldBe(1);
+
+        // Advance past retention + tick drain (which runs PurgeAgedDeadLetters).
+        clock = now.AddDays(31);
+        await sink.DrainOnceAsync(CancellationToken.None);
+
+        sink.GetStatus().DeadLetterDepth.ShouldBe(0, "purged past retention");
+    }
+
+    [Fact]
+    public async Task RetryDeadLettered_requeues_for_retry()
+    {
+        var writer = new FakeWriter();
+        writer.NextOutcomePerEvent.Enqueue(HistorianWriteOutcome.PermanentFail);
+        using var sink = new SqliteStoreAndForwardSink(_dbPath, writer, _log);
+
+        await sink.EnqueueAsync(Event("bad"), CancellationToken.None);
+        await sink.DrainOnceAsync(CancellationToken.None);
+        sink.GetStatus().DeadLetterDepth.ShouldBe(1);
+
+        var revived = sink.RetryDeadLettered();
+        revived.ShouldBe(1);
+
+        var status = sink.GetStatus();
+        status.QueueDepth.ShouldBe(1);
+        status.DeadLetterDepth.ShouldBe(0);
+    }
+
+    [Fact]
+    public async Task Backoff_ladder_caps_at_60s()
+    {
+        var writer = new FakeWriter { DefaultOutcome = HistorianWriteOutcome.RetryPlease };
+        using var sink = new SqliteStoreAndForwardSink(_dbPath, writer, _log);
+
+        await sink.EnqueueAsync(Event("A1"), CancellationToken.None);
+
+        // 10 retry rounds — ladder should cap at 60s.
+        for (var i = 0; i < 10; i++)
+            await sink.DrainOnceAsync(CancellationToken.None);
+
+        sink.CurrentBackoff.ShouldBe(TimeSpan.FromSeconds(60));
+    }
+
+    [Fact]
+    public void NullAlarmHistorianSink_reports_disabled_status()
+    {
+        var s = NullAlarmHistorianSink.Instance.GetStatus();
+        s.DrainState.ShouldBe(HistorianDrainState.Disabled);
+        s.QueueDepth.ShouldBe(0);
+    }
+
+    [Fact]
+    public async Task NullAlarmHistorianSink_swallows_enqueue()
+    {
+        // Should not throw or persist anything.
+        await NullAlarmHistorianSink.Instance.EnqueueAsync(Event("A1"), CancellationToken.None);
+    }
+
+    [Fact]
+    public void Ctor_rejects_bad_args()
+    {
+        var w = new FakeWriter();
+        Should.Throw<ArgumentException>(() => new SqliteStoreAndForwardSink("", w, _log));
+        Should.Throw<ArgumentNullException>(() => new SqliteStoreAndForwardSink(_dbPath, null!, _log));
+        Should.Throw<ArgumentNullException>(() => new SqliteStoreAndForwardSink(_dbPath, w, null!));
+        Should.Throw<ArgumentOutOfRangeException>(() => new SqliteStoreAndForwardSink(_dbPath, w, _log, batchSize: 0));
+        Should.Throw<ArgumentOutOfRangeException>(() => new SqliteStoreAndForwardSink(_dbPath, w, _log, capacity: 0));
+    }
+
+    [Fact]
+    public async Task Disposed_sink_rejects_enqueue()
+    {
+        var writer = new FakeWriter();
+        var sink = new SqliteStoreAndForwardSink(_dbPath, writer, _log);
+        sink.Dispose();
+
+        await Should.ThrowAsync<ObjectDisposedException>(
+            () => sink.EnqueueAsync(Event("A1"), CancellationToken.None));
+    }
+}

tests/ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian.Tests/ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian.Tests.csproj

@@ -0,0 +1,31 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <TargetFramework>net10.0</TargetFramework>
+        <Nullable>enable</Nullable>
+        <ImplicitUsings>enable</ImplicitUsings>
+        <IsPackable>false</IsPackable>
+        <IsTestProject>true</IsTestProject>
+        <RootNamespace>ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian.Tests</RootNamespace>
+    </PropertyGroup>
+
+    <ItemGroup>
+        <PackageReference Include="xunit.v3" Version="1.1.0"/>
+        <PackageReference Include="Shouldly" Version="4.3.0"/>
+        <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.12.0"/>
+        <PackageReference Include="xunit.runner.visualstudio" Version="3.0.2">
+            <PrivateAssets>all</PrivateAssets>
+            <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+        </PackageReference>
+    </ItemGroup>
+
+    <ItemGroup>
+        <ProjectReference Include="..\..\src\ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian\ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian.csproj"/>
+    </ItemGroup>
+
+    <ItemGroup>
+        <NuGetAuditSuppress Include="https://github.com/advisories/GHSA-37gx-xxp4-5rgx"/>
+        <NuGetAuditSuppress Include="https://github.com/advisories/GHSA-w3x6-4m5h-cxqf"/>
+    </ItemGroup>
+
+</Project>

tests/ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms.Tests/FakeUpstream.cs

@@ -0,0 +1,61 @@
+using System.Collections.Concurrent;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+using ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms;
+
+namespace ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms.Tests;
+
+public sealed class FakeUpstream : ITagUpstreamSource
+{
+    private readonly ConcurrentDictionary<string, DataValueSnapshot> _values = new(StringComparer.Ordinal);
+    private readonly ConcurrentDictionary<string, List<Action<string, DataValueSnapshot>>> _subs
+        = new(StringComparer.Ordinal);
+    public int ActiveSubscriptionCount { get; private set; }
+
+    public void Set(string path, object? value, uint statusCode = 0u)
+    {
+        var now = DateTime.UtcNow;
+        _values[path] = new DataValueSnapshot(value, statusCode, now, now);
+    }
+
+    public void Push(string path, object? value, uint statusCode = 0u)
+    {
+        Set(path, value, statusCode);
+        if (_subs.TryGetValue(path, out var list))
+        {
+            Action<string, DataValueSnapshot>[] snap;
+            lock (list) { snap = list.ToArray(); }
+            foreach (var obs in snap) obs(path, _values[path]);
+        }
+    }
+
+    public DataValueSnapshot ReadTag(string path)
+        => _values.TryGetValue(path, out var v) ? v
+            : new DataValueSnapshot(null, 0x80340000u, null, DateTime.UtcNow);
+
+    public IDisposable SubscribeTag(string path, Action<string, DataValueSnapshot> observer)
+    {
+        var list = _subs.GetOrAdd(path, _ => []);
+        lock (list) { list.Add(observer); }
+        ActiveSubscriptionCount++;
+        return new Unsub(this, path, observer);
+    }
+
+    private sealed class Unsub : IDisposable
+    {
+        private readonly FakeUpstream _up;
+        private readonly string _path;
+        private readonly Action<string, DataValueSnapshot> _observer;
+        public Unsub(FakeUpstream up, string path, Action<string, DataValueSnapshot> observer)
+        { _up = up; _path = path; _observer = observer; }
+        public void Dispose()
+        {
+            if (_up._subs.TryGetValue(_path, out var list))
+            {
+                lock (list)
+                {
+                    if (list.Remove(_observer)) _up.ActiveSubscriptionCount--;
+                }
+            }
+        }
+    }
+}

tests/ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms.Tests/MessageTemplateTests.cs

@@ -0,0 +1,107 @@
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+using ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms;
+
+namespace ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms.Tests;
+
+[Trait("Category", "Unit")]
+public sealed class MessageTemplateTests
+{
+    private static DataValueSnapshot Good(object? v) =>
+        new(v, 0u, DateTime.UtcNow, DateTime.UtcNow);
+    private static DataValueSnapshot Bad() =>
+        new(null, 0x80050000u, null, DateTime.UtcNow);
+
+    private static DataValueSnapshot? Resolver(Dictionary<string, DataValueSnapshot> map, string path)
+        => map.TryGetValue(path, out var v) ? v : null;
+
+    [Fact]
+    public void No_tokens_returns_template_unchanged()
+    {
+        MessageTemplate.Resolve("No tokens here", _ => null).ShouldBe("No tokens here");
+    }
+
+    [Fact]
+    public void Single_token_substituted()
+    {
+        var map = new Dictionary<string, DataValueSnapshot> { ["Tank/Temp"] = Good(75.5) };
+        MessageTemplate.Resolve("Temp={Tank/Temp}C", p => Resolver(map, p)).ShouldBe("Temp=75.5C");
+    }
+
+    [Fact]
+    public void Multiple_tokens_substituted()
+    {
+        var map = new Dictionary<string, DataValueSnapshot>
+        {
+            ["A"] = Good(10),
+            ["B"] = Good("on"),
+        };
+        MessageTemplate.Resolve("{A}/{B}", p => Resolver(map, p)).ShouldBe("10/on");
+    }
+
+    [Fact]
+    public void Bad_quality_token_becomes_question_mark()
+    {
+        var map = new Dictionary<string, DataValueSnapshot> { ["Bad"] = Bad() };
+        MessageTemplate.Resolve("value={Bad}", p => Resolver(map, p)).ShouldBe("value={?}");
+    }
+
+    [Fact]
+    public void Unknown_path_becomes_question_mark()
+    {
+        MessageTemplate.Resolve("value={DoesNotExist}", _ => null).ShouldBe("value={?}");
+    }
+
+    [Fact]
+    public void Null_value_with_good_quality_becomes_question_mark()
+    {
+        var map = new Dictionary<string, DataValueSnapshot> { ["X"] = Good(null) };
+        MessageTemplate.Resolve("{X}", p => Resolver(map, p)).ShouldBe("{?}");
+    }
+
+    [Fact]
+    public void Tokens_with_slashes_and_dots_resolved()
+    {
+        var map = new Dictionary<string, DataValueSnapshot>
+        {
+            ["Line1/Pump.Speed"] = Good(1200),
+        };
+        MessageTemplate.Resolve("rpm={Line1/Pump.Speed}", p => Resolver(map, p))
+            .ShouldBe("rpm=1200");
+    }
+
+    [Fact]
+    public void Empty_template_returns_empty()
+    {
+        MessageTemplate.Resolve("", _ => null).ShouldBe("");
+    }
+
+    [Fact]
+    public void Null_template_returns_empty_without_throwing()
+    {
+        MessageTemplate.Resolve(null!, _ => null).ShouldBe("");
+    }
+
+    [Fact]
+    public void ExtractTokenPaths_returns_every_distinct_token()
+    {
+        var tokens = MessageTemplate.ExtractTokenPaths("{A}/{B}/{A}/{C}");
+        tokens.ShouldBe(new[] { "A", "B", "A", "C" });
+    }
+
+    [Fact]
+    public void ExtractTokenPaths_empty_for_tokenless_template()
+    {
+        MessageTemplate.ExtractTokenPaths("No tokens").ShouldBeEmpty();
+        MessageTemplate.ExtractTokenPaths("").ShouldBeEmpty();
+        MessageTemplate.ExtractTokenPaths(null).ShouldBeEmpty();
+    }
+
+    [Fact]
+    public void Whitespace_inside_token_is_trimmed()
+    {
+        var map = new Dictionary<string, DataValueSnapshot> { ["A"] = Good(42) };
+        MessageTemplate.Resolve("{  A  }", p => Resolver(map, p)).ShouldBe("42");
+    }
+}

tests/ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms.Tests/Part9StateMachineTests.cs

@@ -0,0 +1,205 @@
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms;
+
+namespace ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms.Tests;
+
+/// <summary>
+///     Pure state-machine tests — no engine, no I/O, no async. Every transition rule
+///     from Phase 7 plan Stream C.2 / C.3 has at least one locking test so regressions
+///     surface as clear failures rather than subtle alarm-behavior drift.
+/// </summary>
+[Trait("Category", "Unit")]
+public sealed class Part9StateMachineTests
+{
+    private static readonly DateTime T0 = new(2026, 1, 1, 12, 0, 0, DateTimeKind.Utc);
+    private static AlarmConditionState Fresh() => AlarmConditionState.Fresh("alarm-1", T0);
+
+    [Fact]
+    public void Predicate_true_on_inactive_becomes_active_and_emits_Activated()
+    {
+        var r = Part9StateMachine.ApplyPredicate(Fresh(), predicateTrue: true, T0.AddSeconds(1));
+        r.State.Active.ShouldBe(AlarmActiveState.Active);
+        r.State.Acked.ShouldBe(AlarmAckedState.Unacknowledged);
+        r.State.Confirmed.ShouldBe(AlarmConfirmedState.Unconfirmed);
+        r.Emission.ShouldBe(EmissionKind.Activated);
+        r.State.LastActiveUtc.ShouldNotBeNull();
+    }
+
+    [Fact]
+    public void Predicate_false_on_active_becomes_inactive_and_emits_Cleared()
+    {
+        var active = Part9StateMachine.ApplyPredicate(Fresh(), true, T0.AddSeconds(1)).State;
+        var r = Part9StateMachine.ApplyPredicate(active, false, T0.AddSeconds(2));
+        r.State.Active.ShouldBe(AlarmActiveState.Inactive);
+        r.Emission.ShouldBe(EmissionKind.Cleared);
+        r.State.LastClearedUtc.ShouldNotBeNull();
+    }
+
+    [Fact]
+    public void Predicate_unchanged_state_emits_None()
+    {
+        var r = Part9StateMachine.ApplyPredicate(Fresh(), false, T0);
+        r.Emission.ShouldBe(EmissionKind.None);
+    }
+
+    [Fact]
+    public void Disabled_alarm_ignores_predicate()
+    {
+        var disabled = Part9StateMachine.ApplyDisable(Fresh(), "op1", T0.AddSeconds(1)).State;
+        var r = Part9StateMachine.ApplyPredicate(disabled, true, T0.AddSeconds(2));
+        r.State.Active.ShouldBe(AlarmActiveState.Inactive);
+        r.Emission.ShouldBe(EmissionKind.None);
+    }
+
+    [Fact]
+    public void Acknowledge_from_unacked_records_user_and_emits()
+    {
+        var active = Part9StateMachine.ApplyPredicate(Fresh(), true, T0.AddSeconds(1)).State;
+        var r = Part9StateMachine.ApplyAcknowledge(active, "alice", "looking into it", T0.AddSeconds(2));
+        r.State.Acked.ShouldBe(AlarmAckedState.Acknowledged);
+        r.State.LastAckUser.ShouldBe("alice");
+        r.State.LastAckComment.ShouldBe("looking into it");
+        r.State.Comments.Count.ShouldBe(1);
+        r.Emission.ShouldBe(EmissionKind.Acknowledged);
+    }
+
+    [Fact]
+    public void Acknowledge_when_already_acked_is_noop()
+    {
+        var active = Part9StateMachine.ApplyPredicate(Fresh(), true, T0.AddSeconds(1)).State;
+        var acked = Part9StateMachine.ApplyAcknowledge(active, "alice", null, T0.AddSeconds(2)).State;
+        var r = Part9StateMachine.ApplyAcknowledge(acked, "alice", null, T0.AddSeconds(3));
+        r.Emission.ShouldBe(EmissionKind.None);
+    }
+
+    [Fact]
+    public void Acknowledge_without_user_throws()
+    {
+        Should.Throw<ArgumentException>(() =>
+            Part9StateMachine.ApplyAcknowledge(Fresh(), "", null, T0));
+    }
+
+    [Fact]
+    public void Confirm_after_clear_records_user_and_emits()
+    {
+        // Walk: activate -> ack -> clear -> confirm
+        var s = Fresh();
+        s = Part9StateMachine.ApplyPredicate(s, true, T0.AddSeconds(1)).State;
+        s = Part9StateMachine.ApplyAcknowledge(s, "alice", null, T0.AddSeconds(2)).State;
+        s = Part9StateMachine.ApplyPredicate(s, false, T0.AddSeconds(3)).State;
+
+        var r = Part9StateMachine.ApplyConfirm(s, "bob", "resolved", T0.AddSeconds(4));
+        r.State.Confirmed.ShouldBe(AlarmConfirmedState.Confirmed);
+        r.State.LastConfirmUser.ShouldBe("bob");
+        r.Emission.ShouldBe(EmissionKind.Confirmed);
+    }
+
+    [Fact]
+    public void OneShotShelve_suppresses_next_activation_emission()
+    {
+        var s = Part9StateMachine.ApplyOneShotShelve(Fresh(), "alice", T0.AddSeconds(1)).State;
+        var r = Part9StateMachine.ApplyPredicate(s, true, T0.AddSeconds(2));
+        r.State.Active.ShouldBe(AlarmActiveState.Active, "state still advances");
+        r.Emission.ShouldBe(EmissionKind.Suppressed, "but subscribers don't see it");
+    }
+
+    [Fact]
+    public void OneShotShelve_expires_on_clear()
+    {
+        var s = Fresh();
+        s = Part9StateMachine.ApplyOneShotShelve(s, "alice", T0.AddSeconds(1)).State;
+        s = Part9StateMachine.ApplyPredicate(s, true, T0.AddSeconds(2)).State;
+        var r = Part9StateMachine.ApplyPredicate(s, false, T0.AddSeconds(3));
+        r.State.Shelving.Kind.ShouldBe(ShelvingKind.Unshelved, "OneShot expires on clear");
+    }
+
+    [Fact]
+    public void TimedShelve_requires_future_unshelve_time()
+    {
+        Should.Throw<ArgumentOutOfRangeException>(() =>
+            Part9StateMachine.ApplyTimedShelve(Fresh(), "alice", T0, T0.AddSeconds(5)));
+    }
+
+    [Fact]
+    public void TimedShelve_expires_via_shelving_check()
+    {
+        var until = T0.AddMinutes(5);
+        var shelved = Part9StateMachine.ApplyTimedShelve(Fresh(), "alice", until, T0).State;
+        shelved.Shelving.Kind.ShouldBe(ShelvingKind.Timed);
+
+        // Before expiry — still shelved.
+        var earlier = Part9StateMachine.ApplyShelvingCheck(shelved, T0.AddMinutes(3));
+        earlier.State.Shelving.Kind.ShouldBe(ShelvingKind.Timed);
+        earlier.Emission.ShouldBe(EmissionKind.None);
+
+        // After expiry — auto-unshelved + emission.
+        var after = Part9StateMachine.ApplyShelvingCheck(shelved, T0.AddMinutes(6));
+        after.State.Shelving.Kind.ShouldBe(ShelvingKind.Unshelved);
+        after.Emission.ShouldBe(EmissionKind.Unshelved);
+        after.State.Comments.Any(c => c.Kind == "AutoUnshelve").ShouldBeTrue();
+    }
+
+    [Fact]
+    public void Unshelve_from_unshelved_is_noop()
+    {
+        var r = Part9StateMachine.ApplyUnshelve(Fresh(), "alice", T0);
+        r.Emission.ShouldBe(EmissionKind.None);
+    }
+
+    [Fact]
+    public void Explicit_Unshelve_emits_event()
+    {
+        var s = Part9StateMachine.ApplyOneShotShelve(Fresh(), "alice", T0).State;
+        var r = Part9StateMachine.ApplyUnshelve(s, "bob", T0.AddSeconds(30));
+        r.State.Shelving.Kind.ShouldBe(ShelvingKind.Unshelved);
+        r.Emission.ShouldBe(EmissionKind.Unshelved);
+    }
+
+    [Fact]
+    public void AddComment_appends_to_audit_trail_with_event()
+    {
+        var r = Part9StateMachine.ApplyAddComment(Fresh(), "alice", "investigating", T0.AddSeconds(5));
+        r.State.Comments.Count.ShouldBe(1);
+        r.State.Comments[0].Kind.ShouldBe("AddComment");
+        r.State.Comments[0].User.ShouldBe("alice");
+        r.State.Comments[0].Text.ShouldBe("investigating");
+        r.Emission.ShouldBe(EmissionKind.CommentAdded);
+    }
+
+    [Fact]
+    public void Comments_are_append_only_never_rewritten()
+    {
+        var s = Part9StateMachine.ApplyAddComment(Fresh(), "alice", "first", T0.AddSeconds(1)).State;
+        s = Part9StateMachine.ApplyAddComment(s, "bob", "second", T0.AddSeconds(2)).State;
+        s = Part9StateMachine.ApplyAddComment(s, "carol", "third", T0.AddSeconds(3)).State;
+        s.Comments.Count.ShouldBe(3);
+        s.Comments[0].User.ShouldBe("alice");
+        s.Comments[1].User.ShouldBe("bob");
+        s.Comments[2].User.ShouldBe("carol");
+    }
+
+    [Fact]
+    public void Full_lifecycle_walk_produces_every_expected_emission()
+    {
+        // Walk a condition through its whole lifecycle and make sure emissions line up.
+        var emissions = new List<EmissionKind>();
+        var s = Fresh();
+
+        s = Capture(Part9StateMachine.ApplyPredicate(s, true, T0.AddSeconds(1)));
+        s = Capture(Part9StateMachine.ApplyAcknowledge(s, "alice", null, T0.AddSeconds(2)));
+        s = Capture(Part9StateMachine.ApplyAddComment(s, "alice", "need to investigate", T0.AddSeconds(3)));
+        s = Capture(Part9StateMachine.ApplyPredicate(s, false, T0.AddSeconds(4)));
+        s = Capture(Part9StateMachine.ApplyConfirm(s, "bob", null, T0.AddSeconds(5)));
+
+        emissions.ShouldBe(new[] {
+            EmissionKind.Activated,
+            EmissionKind.Acknowledged,
+            EmissionKind.CommentAdded,
+            EmissionKind.Cleared,
+            EmissionKind.Confirmed,
+        });
+
+        AlarmConditionState Capture(TransitionResult r) { emissions.Add(r.Emission); return r.State; }
+    }
+}

tests/ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms.Tests/ScriptedAlarmEngineTests.cs

@@ -0,0 +1,316 @@
+using Serilog;
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+using ZB.MOM.WW.OtOpcUa.Core.Scripting;
+using ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms;
+
+namespace ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms.Tests;
+
+/// <summary>
+///     End-to-end engine tests: load, predicate evaluation, change-triggered
+///     re-evaluation, state persistence, startup recovery, error isolation.
+/// </summary>
+[Trait("Category", "Unit")]
+public sealed class ScriptedAlarmEngineTests
+{
+    private static ScriptedAlarmEngine Build(FakeUpstream up, out IAlarmStateStore store)
+    {
+        store = new InMemoryAlarmStateStore();
+        var logger = new LoggerConfiguration().CreateLogger();
+        return new ScriptedAlarmEngine(up, store, new ScriptLoggerFactory(logger), logger);
+    }
+
+    private static ScriptedAlarmDefinition Alarm(string id, string predicate,
+        string msg = "condition", AlarmSeverity sev = AlarmSeverity.High) =>
+        new(AlarmId: id,
+            EquipmentPath: "Plant/Line1/Reactor",
+            AlarmName: id,
+            Kind: AlarmKind.AlarmCondition,
+            Severity: sev,
+            MessageTemplate: msg,
+            PredicateScriptSource: predicate);
+
+    [Fact]
+    public async Task Load_compiles_and_subscribes_to_referenced_upstreams()
+    {
+        var up = new FakeUpstream();
+        up.Set("Temp", 50);
+        using var eng = Build(up, out _);
+
+        await eng.LoadAsync([Alarm("a1", """return (int)ctx.GetTag("Temp").Value > 100;""")],
+            TestContext.Current.CancellationToken);
+
+        eng.LoadedAlarmIds.ShouldContain("a1");
+        up.ActiveSubscriptionCount.ShouldBe(1);
+    }
+
+    [Fact]
+    public async Task Compile_failures_aggregated_into_one_error()
+    {
+        var up = new FakeUpstream();
+        using var eng = Build(up, out _);
+
+        var ex = await Should.ThrowAsync<InvalidOperationException>(async () =>
+            await eng.LoadAsync([
+                Alarm("bad1", "return unknownIdentifier;"),
+                Alarm("good", "return true;"),
+                Alarm("bad2", "var x = alsoUnknown; return x;"),
+            ], TestContext.Current.CancellationToken));
+        ex.Message.ShouldContain("2 alarm(s) did not compile");
+    }
+
+    [Fact]
+    public async Task Upstream_change_re_evaluates_predicate_and_emits_Activated()
+    {
+        var up = new FakeUpstream();
+        up.Set("Temp", 50);
+        using var eng = Build(up, out _);
+        await eng.LoadAsync([Alarm("HighTemp", """return (int)ctx.GetTag("Temp").Value > 100;""")],
+            TestContext.Current.CancellationToken);
+
+        var events = new List<ScriptedAlarmEvent>();
+        eng.OnEvent += (_, e) => events.Add(e);
+
+        up.Push("Temp", 150);
+        await WaitForAsync(() => events.Count > 0);
+
+        events[0].AlarmId.ShouldBe("HighTemp");
+        events[0].Emission.ShouldBe(EmissionKind.Activated);
+        eng.GetState("HighTemp")!.Active.ShouldBe(AlarmActiveState.Active);
+    }
+
+    [Fact]
+    public async Task Clearing_upstream_emits_Cleared_event()
+    {
+        var up = new FakeUpstream();
+        up.Set("Temp", 150);
+        using var eng = Build(up, out _);
+        await eng.LoadAsync([Alarm("HighTemp", """return (int)ctx.GetTag("Temp").Value > 100;""")],
+            TestContext.Current.CancellationToken);
+
+        // Startup sees 150 → active.
+        eng.GetState("HighTemp")!.Active.ShouldBe(AlarmActiveState.Active);
+
+        var events = new List<ScriptedAlarmEvent>();
+        eng.OnEvent += (_, e) => events.Add(e);
+
+        up.Push("Temp", 50);
+        await WaitForAsync(() => events.Any(e => e.Emission == EmissionKind.Cleared));
+        eng.GetState("HighTemp")!.Active.ShouldBe(AlarmActiveState.Inactive);
+    }
+
+    [Fact]
+    public async Task Message_template_resolves_tag_values_at_emission()
+    {
+        var up = new FakeUpstream();
+        up.Set("Temp", 50);
+        up.Set("Limit", 100);
+        using var eng = Build(up, out _);
+        await eng.LoadAsync([
+            new ScriptedAlarmDefinition(
+                "HighTemp", "Plant/Line1", "HighTemp",
+                AlarmKind.LimitAlarm, AlarmSeverity.High,
+                "Temp {Temp}C exceeded limit {Limit}C",
+                """return (int)ctx.GetTag("Temp").Value > (int)ctx.GetTag("Limit").Value;"""),
+        ], TestContext.Current.CancellationToken);
+
+        var events = new List<ScriptedAlarmEvent>();
+        eng.OnEvent += (_, e) => events.Add(e);
+
+        up.Push("Temp", 150);
+        await WaitForAsync(() => events.Any());
+
+        events[0].Message.ShouldBe("Temp 150C exceeded limit 100C");
+    }
+
+    [Fact]
+    public async Task Ack_records_user_and_persists_to_store()
+    {
+        var up = new FakeUpstream();
+        up.Set("Temp", 150);
+        using var eng = Build(up, out var store);
+        await eng.LoadAsync([Alarm("HighTemp", """return (int)ctx.GetTag("Temp").Value > 100;""")],
+            TestContext.Current.CancellationToken);
+
+        await eng.AcknowledgeAsync("HighTemp", "alice", "checking", TestContext.Current.CancellationToken);
+
+        var persisted = await store.LoadAsync("HighTemp", TestContext.Current.CancellationToken);
+        persisted.ShouldNotBeNull();
+        persisted!.Acked.ShouldBe(AlarmAckedState.Acknowledged);
+        persisted.LastAckUser.ShouldBe("alice");
+        persisted.LastAckComment.ShouldBe("checking");
+        persisted.Comments.Any(c => c.Kind == "Acknowledge" && c.User == "alice").ShouldBeTrue();
+    }
+
+    [Fact]
+    public async Task Startup_recovery_preserves_ack_but_rederives_active_from_predicate()
+    {
+        var up = new FakeUpstream();
+        up.Set("Temp", 50); // predicate will go false on second load
+
+        // First run — alarm goes active + operator acks.
+        using (var eng1 = Build(up, out var sharedStore))
+        {
+            up.Set("Temp", 150);
+            await eng1.LoadAsync([Alarm("HighTemp", """return (int)ctx.GetTag("Temp").Value > 100;""")],
+                TestContext.Current.CancellationToken);
+            eng1.GetState("HighTemp")!.Active.ShouldBe(AlarmActiveState.Active);
+
+            await eng1.AcknowledgeAsync("HighTemp", "alice", null, TestContext.Current.CancellationToken);
+            eng1.GetState("HighTemp")!.Acked.ShouldBe(AlarmAckedState.Acknowledged);
+        }
+
+        // Simulate restart — temp is back to 50 (below threshold).
+        up.Set("Temp", 50);
+        var logger = new LoggerConfiguration().CreateLogger();
+        var store2 = new InMemoryAlarmStateStore();
+        // seed store2 with the acked state from before restart
+        await store2.SaveAsync(new AlarmConditionState(
+            "HighTemp",
+            AlarmEnabledState.Enabled,
+            AlarmActiveState.Active,         // was active pre-restart
+            AlarmAckedState.Acknowledged,    // ack persisted
+            AlarmConfirmedState.Unconfirmed,
+            ShelvingState.Unshelved,
+            DateTime.UtcNow,
+            DateTime.UtcNow, null,
+            DateTime.UtcNow, "alice", null,
+            null, null, null,
+            [new AlarmComment(DateTime.UtcNow, "alice", "Acknowledge", "")]),
+            TestContext.Current.CancellationToken);
+
+        using var eng2 = new ScriptedAlarmEngine(up, store2, new ScriptLoggerFactory(logger), logger);
+        await eng2.LoadAsync([Alarm("HighTemp", """return (int)ctx.GetTag("Temp").Value > 100;""")],
+            TestContext.Current.CancellationToken);
+
+        var s = eng2.GetState("HighTemp")!;
+        s.Active.ShouldBe(AlarmActiveState.Inactive, "Active recomputed from current tag value");
+        s.Acked.ShouldBe(AlarmAckedState.Acknowledged, "Ack persisted across restart");
+        s.LastAckUser.ShouldBe("alice");
+    }
+
+    [Fact]
+    public async Task Shelved_active_transitions_state_but_suppresses_emission()
+    {
+        var up = new FakeUpstream();
+        up.Set("Temp", 50);
+        using var eng = Build(up, out _);
+        await eng.LoadAsync([Alarm("HighTemp", """return (int)ctx.GetTag("Temp").Value > 100;""")],
+            TestContext.Current.CancellationToken);
+
+        await eng.OneShotShelveAsync("HighTemp", "alice", TestContext.Current.CancellationToken);
+
+        var events = new List<ScriptedAlarmEvent>();
+        eng.OnEvent += (_, e) => events.Add(e);
+
+        up.Push("Temp", 150);
+        await Task.Delay(200);
+
+        events.Any(e => e.Emission == EmissionKind.Activated).ShouldBeFalse(
+            "OneShot shelve suppresses activation emission");
+        eng.GetState("HighTemp")!.Active.ShouldBe(AlarmActiveState.Active,
+            "state still advances so startup recovery is consistent");
+    }
+
+    [Fact]
+    public async Task Predicate_runtime_exception_does_not_transition_state()
+    {
+        var up = new FakeUpstream();
+        up.Set("Temp", 150);
+        using var eng = Build(up, out _);
+        await eng.LoadAsync([
+            Alarm("BadScript", """throw new InvalidOperationException("boom");"""),
+            Alarm("GoodScript", """return (int)ctx.GetTag("Temp").Value > 100;"""),
+        ], TestContext.Current.CancellationToken);
+
+        // Bad script doesn't activate + doesn't disable other alarms.
+        eng.GetState("BadScript")!.Active.ShouldBe(AlarmActiveState.Inactive);
+        eng.GetState("GoodScript")!.Active.ShouldBe(AlarmActiveState.Active);
+    }
+
+    [Fact]
+    public async Task Disable_prevents_activation_until_re_enabled()
+    {
+        var up = new FakeUpstream();
+        up.Set("Temp", 50);
+        using var eng = Build(up, out _);
+        await eng.LoadAsync([Alarm("HighTemp", """return (int)ctx.GetTag("Temp").Value > 100;""")],
+            TestContext.Current.CancellationToken);
+
+        await eng.DisableAsync("HighTemp", "alice", TestContext.Current.CancellationToken);
+        up.Push("Temp", 150);
+        await Task.Delay(100);
+        eng.GetState("HighTemp")!.Active.ShouldBe(AlarmActiveState.Inactive,
+            "disabled alarm ignores predicate");
+
+        await eng.EnableAsync("HighTemp", "alice", TestContext.Current.CancellationToken);
+        up.Push("Temp", 160);
+        await WaitForAsync(() => eng.GetState("HighTemp")!.Active == AlarmActiveState.Active);
+    }
+
+    [Fact]
+    public async Task AddComment_appends_to_audit_without_state_change()
+    {
+        var up = new FakeUpstream();
+        up.Set("Temp", 50);
+        using var eng = Build(up, out var store);
+        await eng.LoadAsync([Alarm("A", """return false;""")], TestContext.Current.CancellationToken);
+
+        await eng.AddCommentAsync("A", "alice", "peeking at this", TestContext.Current.CancellationToken);
+
+        var s = await store.LoadAsync("A", TestContext.Current.CancellationToken);
+        s.ShouldNotBeNull();
+        s!.Comments.Count.ShouldBe(1);
+        s.Comments[0].User.ShouldBe("alice");
+        s.Comments[0].Kind.ShouldBe("AddComment");
+    }
+
+    [Fact]
+    public async Task Predicate_scripts_cannot_SetVirtualTag()
+    {
+        var up = new FakeUpstream();
+        up.Set("Temp", 100);
+        using var eng = Build(up, out _);
+
+        // The script compiles fine but throws at runtime when SetVirtualTag is called.
+        // The engine swallows the exception + leaves state unchanged.
+        await eng.LoadAsync([
+            new ScriptedAlarmDefinition(
+                "Bad", "Plant/Line1", "Bad",
+                AlarmKind.AlarmCondition, AlarmSeverity.High, "bad",
+                """
+                ctx.SetVirtualTag("NotAllowed", 1);
+                return true;
+                """),
+        ], TestContext.Current.CancellationToken);
+
+        // Bad alarm's predicate threw — state unchanged.
+        eng.GetState("Bad")!.Active.ShouldBe(AlarmActiveState.Inactive);
+    }
+
+    [Fact]
+    public async Task Dispose_releases_upstream_subscriptions()
+    {
+        var up = new FakeUpstream();
+        up.Set("Temp", 50);
+        var eng = Build(up, out _);
+        await eng.LoadAsync([Alarm("A", """return (int)ctx.GetTag("Temp").Value > 100;""")],
+            TestContext.Current.CancellationToken);
+        up.ActiveSubscriptionCount.ShouldBe(1);
+
+        eng.Dispose();
+        up.ActiveSubscriptionCount.ShouldBe(0);
+    }
+
+    private static async Task WaitForAsync(Func<bool> cond, int timeoutMs = 2000)
+    {
+        var deadline = DateTime.UtcNow.AddMilliseconds(timeoutMs);
+        while (DateTime.UtcNow < deadline)
+        {
+            if (cond()) return;
+            await Task.Delay(25);
+        }
+        throw new TimeoutException("Condition did not become true in time");
+    }
+}

tests/ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms.Tests/ScriptedAlarmSourceTests.cs

@@ -0,0 +1,142 @@
+using Serilog;
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+using ZB.MOM.WW.OtOpcUa.Core.Scripting;
+using ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms;
+
+namespace ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms.Tests;
+
+[Trait("Category", "Unit")]
+public sealed class ScriptedAlarmSourceTests
+{
+    private static async Task<(ScriptedAlarmEngine e, ScriptedAlarmSource s, FakeUpstream u)> BuildAsync()
+    {
+        var up = new FakeUpstream();
+        up.Set("Temp", 50);
+        var logger = new LoggerConfiguration().CreateLogger();
+        var engine = new ScriptedAlarmEngine(up, new InMemoryAlarmStateStore(),
+            new ScriptLoggerFactory(logger), logger);
+        await engine.LoadAsync([
+            new ScriptedAlarmDefinition(
+                "Plant/Line1::HighTemp",
+                "Plant/Line1",
+                "HighTemp",
+                AlarmKind.LimitAlarm,
+                AlarmSeverity.High,
+                "Temp {Temp}C",
+                """return (int)ctx.GetTag("Temp").Value > 100;"""),
+            new ScriptedAlarmDefinition(
+                "Plant/Line2::OtherAlarm",
+                "Plant/Line2",
+                "OtherAlarm",
+                AlarmKind.AlarmCondition,
+                AlarmSeverity.Low,
+                "other",
+                """return false;"""),
+        ], CancellationToken.None);
+
+        var source = new ScriptedAlarmSource(engine);
+        return (engine, source, up);
+    }
+
+    [Fact]
+    public async Task Subscribe_with_empty_filter_receives_every_alarm_emission()
+    {
+        var (engine, source, up) = await BuildAsync();
+        using var _e = engine;
+        using var _s = source;
+
+        var events = new List<AlarmEventArgs>();
+        source.OnAlarmEvent += (_, e) => events.Add(e);
+        var handle = await source.SubscribeAlarmsAsync([], TestContext.Current.CancellationToken);
+
+        up.Push("Temp", 150);
+        await Task.Delay(200);
+
+        events.Count.ShouldBe(1);
+        events[0].ConditionId.ShouldBe("Plant/Line1::HighTemp");
+        events[0].SourceNodeId.ShouldBe("Plant/Line1");
+        events[0].Severity.ShouldBe(AlarmSeverity.High);
+        events[0].AlarmType.ShouldBe("LimitAlarm");
+        events[0].Message.ShouldBe("Temp 150C");
+
+        await source.UnsubscribeAlarmsAsync(handle, TestContext.Current.CancellationToken);
+    }
+
+    [Fact]
+    public async Task Subscribe_with_equipment_prefix_filters_by_that_prefix()
+    {
+        var (engine, source, up) = await BuildAsync();
+        using var _e = engine;
+        using var _s = source;
+
+        var events = new List<AlarmEventArgs>();
+        source.OnAlarmEvent += (_, e) => events.Add(e);
+
+        // Subscribe only to Line1 alarms.
+        var handle = await source.SubscribeAlarmsAsync(["Plant/Line1"], TestContext.Current.CancellationToken);
+
+        up.Push("Temp", 150);
+        await Task.Delay(200);
+
+        events.Count.ShouldBe(1);
+        events[0].SourceNodeId.ShouldBe("Plant/Line1");
+
+        await source.UnsubscribeAlarmsAsync(handle, TestContext.Current.CancellationToken);
+    }
+
+    [Fact]
+    public async Task Unsubscribe_stops_further_events()
+    {
+        var (engine, source, up) = await BuildAsync();
+        using var _e = engine;
+        using var _s = source;
+
+        var events = new List<AlarmEventArgs>();
+        source.OnAlarmEvent += (_, e) => events.Add(e);
+        var handle = await source.SubscribeAlarmsAsync([], TestContext.Current.CancellationToken);
+        await source.UnsubscribeAlarmsAsync(handle, TestContext.Current.CancellationToken);
+
+        up.Push("Temp", 150);
+        await Task.Delay(200);
+
+        events.Count.ShouldBe(0);
+    }
+
+    [Fact]
+    public async Task AcknowledgeAsync_routes_to_engine_with_default_user()
+    {
+        var (engine, source, up) = await BuildAsync();
+        using var _e = engine;
+        using var _s = source;
+
+        up.Push("Temp", 150);
+        await Task.Delay(200);
+        engine.GetState("Plant/Line1::HighTemp")!.Acked.ShouldBe(AlarmAckedState.Unacknowledged);
+
+        await source.AcknowledgeAsync([new AlarmAcknowledgeRequest(
+            "Plant/Line1", "Plant/Line1::HighTemp", "ack via opcua")],
+            TestContext.Current.CancellationToken);
+
+        var state = engine.GetState("Plant/Line1::HighTemp")!;
+        state.Acked.ShouldBe(AlarmAckedState.Acknowledged);
+        state.LastAckUser.ShouldBe("opcua-client");
+        state.LastAckComment.ShouldBe("ack via opcua");
+    }
+
+    [Fact]
+    public async Task Null_arguments_rejected()
+    {
+        var (engine, source, _) = await BuildAsync();
+        using var _e = engine;
+        using var _s = source;
+
+        await Should.ThrowAsync<ArgumentNullException>(async () =>
+            await source.SubscribeAlarmsAsync(null!, TestContext.Current.CancellationToken));
+        await Should.ThrowAsync<ArgumentNullException>(async () =>
+            await source.UnsubscribeAlarmsAsync(null!, TestContext.Current.CancellationToken));
+        await Should.ThrowAsync<ArgumentNullException>(async () =>
+            await source.AcknowledgeAsync(null!, TestContext.Current.CancellationToken));
+    }
+}

tests/ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms.Tests/ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms.Tests.csproj

@@ -0,0 +1,31 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <TargetFramework>net10.0</TargetFramework>
+        <Nullable>enable</Nullable>
+        <ImplicitUsings>enable</ImplicitUsings>
+        <IsPackable>false</IsPackable>
+        <IsTestProject>true</IsTestProject>
+        <RootNamespace>ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms.Tests</RootNamespace>
+    </PropertyGroup>
+
+    <ItemGroup>
+        <PackageReference Include="xunit.v3" Version="1.1.0"/>
+        <PackageReference Include="Shouldly" Version="4.3.0"/>
+        <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.12.0"/>
+        <PackageReference Include="xunit.runner.visualstudio" Version="3.0.2">
+            <PrivateAssets>all</PrivateAssets>
+            <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+        </PackageReference>
+    </ItemGroup>
+
+    <ItemGroup>
+        <ProjectReference Include="..\..\src\ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms\ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms.csproj"/>
+    </ItemGroup>
+
+    <ItemGroup>
+        <NuGetAuditSuppress Include="https://github.com/advisories/GHSA-37gx-xxp4-5rgx"/>
+        <NuGetAuditSuppress Include="https://github.com/advisories/GHSA-w3x6-4m5h-cxqf"/>
+    </ItemGroup>
+
+</Project>

tests/ZB.MOM.WW.OtOpcUa.Core.Tests/OpcUa/EquipmentNodeWalkerTests.cs

@@ -147,6 +147,117 @@ public sealed class EquipmentNodeWalkerTests
         variable.AttributeInfo.DriverDataType.ShouldBe(DriverDataType.String);
     }
 
+    [Fact]
+    public void Walk_Emits_VirtualTag_Variables_With_Virtual_Source_Discriminator()
+    {
+        var eq = Eq("eq-1", "line-1", "oven-3");
+        var vtag = new VirtualTag
+        {
+            VirtualTagRowId = Guid.NewGuid(), GenerationId = 1,
+            VirtualTagId = "vt-1", EquipmentId = "eq-1", Name = "LineRate",
+            DataType = "Float32", ScriptId = "scr-1", Historize = true,
+        };
+        var content = new EquipmentNamespaceContent(
+            [Area("area-1", "warsaw")], [Line("line-1", "area-1", "line-a")],
+            [eq], [], VirtualTags: [vtag]);
+
+        var rec = new RecordingBuilder("root");
+        EquipmentNodeWalker.Walk(rec, content);
+
+        var equipmentNode = rec.Children[0].Children[0].Children[0];
+        var v = equipmentNode.Variables.Single(x => x.BrowseName == "LineRate");
+        v.AttributeInfo.Source.ShouldBe(NodeSourceKind.Virtual);
+        v.AttributeInfo.VirtualTagId.ShouldBe("vt-1");
+        v.AttributeInfo.ScriptedAlarmId.ShouldBeNull();
+        v.AttributeInfo.IsHistorized.ShouldBeTrue();
+        v.AttributeInfo.DriverDataType.ShouldBe(DriverDataType.Float32);
+    }
+
+    [Fact]
+    public void Walk_Emits_ScriptedAlarm_Variables_With_ScriptedAlarm_Source_And_IsAlarm()
+    {
+        var eq = Eq("eq-1", "line-1", "oven-3");
+        var alarm = new ScriptedAlarm
+        {
+            ScriptedAlarmRowId = Guid.NewGuid(), GenerationId = 1,
+            ScriptedAlarmId = "al-1", EquipmentId = "eq-1", Name = "HighTemp",
+            AlarmType = "LimitAlarm", MessageTemplate = "{Temp} exceeded",
+            PredicateScriptId = "scr-9", Severity = 800,
+        };
+        var content = new EquipmentNamespaceContent(
+            [Area("area-1", "warsaw")], [Line("line-1", "area-1", "line-a")],
+            [eq], [], ScriptedAlarms: [alarm]);
+
+        var rec = new RecordingBuilder("root");
+        EquipmentNodeWalker.Walk(rec, content);
+
+        var v = rec.Children[0].Children[0].Children[0].Variables.Single(x => x.BrowseName == "HighTemp");
+        v.AttributeInfo.Source.ShouldBe(NodeSourceKind.ScriptedAlarm);
+        v.AttributeInfo.ScriptedAlarmId.ShouldBe("al-1");
+        v.AttributeInfo.VirtualTagId.ShouldBeNull();
+        v.AttributeInfo.IsAlarm.ShouldBeTrue();
+        v.AttributeInfo.DriverDataType.ShouldBe(DriverDataType.Boolean);
+    }
+
+    [Fact]
+    public void Walk_Skips_Disabled_VirtualTags_And_Alarms()
+    {
+        var eq = Eq("eq-1", "line-1", "oven-3");
+        var vtag = new VirtualTag
+        {
+            VirtualTagRowId = Guid.NewGuid(), GenerationId = 1,
+            VirtualTagId = "vt-1", EquipmentId = "eq-1", Name = "Disabled",
+            DataType = "Float32", ScriptId = "scr-1", Enabled = false,
+        };
+        var alarm = new ScriptedAlarm
+        {
+            ScriptedAlarmRowId = Guid.NewGuid(), GenerationId = 1,
+            ScriptedAlarmId = "al-1", EquipmentId = "eq-1", Name = "DisabledAlarm",
+            AlarmType = "LimitAlarm", MessageTemplate = "x",
+            PredicateScriptId = "scr-9", Enabled = false,
+        };
+        var content = new EquipmentNamespaceContent(
+            [Area("area-1", "warsaw")], [Line("line-1", "area-1", "line-a")],
+            [eq], [], VirtualTags: [vtag], ScriptedAlarms: [alarm]);
+
+        var rec = new RecordingBuilder("root");
+        EquipmentNodeWalker.Walk(rec, content);
+
+        rec.Children[0].Children[0].Children[0].Variables.ShouldBeEmpty();
+    }
+
+    [Fact]
+    public void Walk_Null_VirtualTags_And_ScriptedAlarms_Is_Safe()
+    {
+        // Backwards-compat — callers that don't populate the new collections still work.
+        var eq = Eq("eq-1", "line-1", "oven-3");
+        var content = new EquipmentNamespaceContent(
+            [Area("area-1", "warsaw")], [Line("line-1", "area-1", "line-a")], [eq], []);
+
+        var rec = new RecordingBuilder("root");
+        EquipmentNodeWalker.Walk(rec, content);  // must not throw
+
+        rec.Children[0].Children[0].Children[0].Variables.ShouldBeEmpty();
+    }
+
+    [Fact]
+    public void Driver_tag_default_NodeSourceKind_is_Driver()
+    {
+        var eq = Eq("eq-1", "line-1", "oven-3");
+        var tag = NewTag("t-1", "Temp", "Int32", "plc-01", "eq-1");
+        var content = new EquipmentNamespaceContent(
+            [Area("area-1", "warsaw")], [Line("line-1", "area-1", "line-a")],
+            [eq], [tag]);
+
+        var rec = new RecordingBuilder("root");
+        EquipmentNodeWalker.Walk(rec, content);
+
+        var v = rec.Children[0].Children[0].Children[0].Variables.Single();
+        v.AttributeInfo.Source.ShouldBe(NodeSourceKind.Driver);
+        v.AttributeInfo.VirtualTagId.ShouldBeNull();
+        v.AttributeInfo.ScriptedAlarmId.ShouldBeNull();
+    }
+
     // ----- builders for test seed rows -----
 
     private static UnsArea Area(string id, string name) => new()