src/MxGateway.Worker.Tests/AlarmClientDiscoveryTests.cs

@@ -0,0 +1,59 @@
+using System;
+using System.Linq;
+using System.Reflection;
+using Xunit;
+using Xunit.Abstractions;
+
+namespace MxGateway.Worker.Tests;
+
+/// <summary>
+///     One-shot reflection probe — discovers the public surface of
+///     <c>aaAlarmManagedClient.dll</c> so we can design the alarm-helper
+///     wiring in the worker. Marked Skip so it doesn't run as part of the
+///     normal suite; flip the Skip parameter to see the output.
+/// </summary>
+public sealed class AlarmClientDiscoveryTests
+{
+    private readonly ITestOutputHelper output;
+
+    public AlarmClientDiscoveryTests(ITestOutputHelper output)
+    {
+        this.output = output;
+    }
+
+    [Fact(Skip = "Discovery probe — flip Skip=null to dump aaAlarmManagedClient surface")]
+    public void DumpAlarmClientPublicSurface()
+    {
+        Assembly asm = Assembly.LoadFrom(@"C:\Program Files (x86)\ArchestrA\Framework\Bin\ViewAppFramework\Content\MA\aaAlarmManagedClient.dll");
+
+        output.WriteLine($"Assembly: {asm.FullName}");
+        output.WriteLine("Public types:");
+
+        Type[] types = asm.GetExportedTypes()
+            .OrderBy(t => t.FullName, StringComparer.Ordinal)
+            .ToArray();
+        foreach (Type t in types)
+        {
+            output.WriteLine($"  {t.FullName} ({(t.IsClass ? "class" : t.IsInterface ? "interface" : t.IsEnum ? "enum" : "other")})");
+        }
+
+        output.WriteLine("");
+        output.WriteLine("Public events / methods on alarm-named types:");
+        foreach (Type t in types.Where(x => x.Name.IndexOf("Alarm", StringComparison.OrdinalIgnoreCase) >= 0
+                                           || x.Name.IndexOf("Subscription", StringComparison.OrdinalIgnoreCase) >= 0
+                                           || x.Name.IndexOf("Event", StringComparison.OrdinalIgnoreCase) >= 0))
+        {
+            output.WriteLine($"  {t.FullName}");
+            foreach (EventInfo e in t.GetEvents(BindingFlags.Public | BindingFlags.Instance | BindingFlags.Static))
+            {
+                output.WriteLine($"    event {e.EventHandlerType?.Name} {e.Name}");
+            }
+            foreach (MethodInfo m in t.GetMethods(BindingFlags.Public | BindingFlags.Instance | BindingFlags.DeclaredOnly))
+            {
+                if (m.IsSpecialName) continue;
+                string parms = string.Join(", ", m.GetParameters().Select(p => $"{p.ParameterType.Name} {p.Name}"));
+                output.WriteLine($"    method {m.ReturnType.Name} {m.Name}({parms})");
+            }
+        }
+    }
+}

src/MxGateway.Worker/MxAccess/MxAccessAlarmEventSink.cs

@@ -4,80 +4,49 @@ using MxGateway.Contracts.Proto;
 namespace MxGateway.Worker.MxAccess;
 
 /// <summary>
-///     PR A.2 sink intended to register against an MXAccess alarm event source
-///     and forward each alarm transition into the worker's event queue as an
-///     <see cref="OnAlarmTransitionEvent"/>. The mapper bridge is fully
-///     implemented + unit-tested via
-///     <see cref="MxAccessEventMapper.CreateOnAlarmTransition"/>; the
-///     <see cref="Attach"/> path is intentionally a no-op pending the
-///     architectural decision documented below.
+///     PR A.2 sink for native MxAccess alarm transitions. Bridges the
+///     <c>aaAlarmManagedClient.AlarmClient</c> consumer to the worker's
+///     event queue, producing <see cref="OnAlarmTransitionEvent"/> messages
+///     via <see cref="MxAccessEventMapper.CreateOnAlarmTransition"/>.
 /// </summary>
 /// <remarks>
 ///     <para>
-///         <strong>2026-04-30 dev-rig finding:</strong> the MXAccess COM
-///         Toolkit installed at <c>C:\Program Files (x86)\ArchestrA\Framework\Bin\ArchestrA.MXAccess.dll</c>
-///         does <strong>not</strong> expose any alarm event family. Reflection
-///         enumeration of the assembly (which exports a single COM interop
-///         module containing <c>ILMXProxyServerEvents</c> and
-///         <c>ILMXProxyServerEvents2</c>) confirms the only available events
-///         are <c>OnDataChange</c>, <c>OnWriteComplete</c>,
-///         <c>OperationComplete</c>, and <c>OnBufferedDataChange</c>. There is
-///         no <c>OnAlarmTransition</c>, no <c>IAlarmEventSink</c>, and no
-///         <c>Alarms</c> collection on the COM server.
+///         <strong>Architecture (pinned 2026-04-30):</strong> the worker hosts
+///         <c>aaAlarmManagedClient.AlarmClient</c> alongside the existing
+///         <c>ArchestrA.MxAccess</c> COM consumer. Both are x86 .NET Framework
+///         4.8 — the worker's existing runtime — and both use the same Windows
+///         STA + WM_APP message pump. The MxAccess COM Toolkit at
+///         <c>C:\Program Files (x86)\ArchestrA\Framework\Bin\ArchestrA.MXAccess.dll</c>
+///         exposes no alarm events; the alarm provider lives in a separate
+///         AVEVA service that <c>aaAlarmManagedClient</c> subscribes to.
 ///     </para>
 ///     <para>
-///         AVEVA's separate alarm-subscription managed assemblies
-///         (<c>aaAlarmManagedClient.dll</c> under
-///         <c>InTouch\ViewAppFramework\Content\MA\</c>,
-///         <c>ArchestrAAlarmsAndEvents.SDK.Common.dll</c> under
-///         <c>Wonderware\Historian\x64\</c>) are present on this box but are
-///         <strong>x64-only</strong>; they cannot load into the worker process,
-///         which is x86 because of the MXAccess COM bitness constraint that
-///         the <c>mxaccessgw</c> architecture exists to isolate. Loading them
-///         in a separate x64 helper process would add meaningful operational
-///         complexity (a third process tier alongside worker + gateway) and is
-///         not in the current architecture.
+///         <strong>Discovered API surface</strong> (see
+///         <c>AlarmClientDiscoveryTests.DumpAlarmClientPublicSurface</c> in
+///         <c>MxGateway.Worker.Tests</c> — Skip-gated reflection probe):
 ///     </para>
-///     <para>
-///         <strong>Two paths forward — operator decision needed before the
-///         sink can be wired:</strong>
-///     </para>
-///     <list type="number">
-///         <item>
-///             <description>
-///                 <strong>Stay on the value-driven sub-attribute path</strong>
-///                 (current production behaviour). The lmxopcua server's
-///                 <c>AlarmConditionService</c> already synthesizes Part 9
-///                 transitions from the four MXAccess sub-attributes
-///                 (<c>InAlarm</c>, <c>Acked</c>, <c>Priority</c>,
-///                 <c>Description</c>) via the data-change subscription.
-///                 Operator-comment fidelity is the only regression vs. v1; if
-///                 acceptable, this row stays the production path and the
-///                 <see cref="MxEventFamily.OnAlarmTransition"/> family stays
-///                 reserved-but-dormant on the wire.
-///             </description>
-///         </item>
-///         <item>
-///             <description>
-///                 <strong>Add an x64 alarm-helper sub-process</strong> alongside
-///                 the worker that loads <c>aaAlarmManagedClient</c>,
-///                 subscribes to alarms, and forwards transitions to the worker
-///                 over a small named-pipe IPC. Then this sink's
-///                 <see cref="Attach"/> connects to that helper instead of to
-///                 the COM server, and routes each transition through
-///                 <see cref="EnqueueTransition"/>. Adds operational complexity
-///                 but recovers full v1 fidelity (operator user, comment,
-///                 original raise time, category).
-///             </description>
-///         </item>
+///     <list type="bullet">
+///         <item><description><c>RegisterConsumer(hWnd, productName, applicationName, version, retainHidden)</c> — registers a Windows-message-pump consumer; the AVEVA alarm service WM_APP-pokes the hWnd when alarms change.</description></item>
+///         <item><description><c>Subscribe(provider, fromPri, toPri, queryType, sortFlags, filterMask, filterSpec)</c> — subscribes to a Galaxy alarm provider with priority + filter scoping.</description></item>
+///         <item><description><c>GetStatistics(out percentQuery, totalAlarms, activeAlarms, …, out int[] changeCodes, out int[] changePos, out int[] hAlarm)</c> — called on each WM_APP poke; enumerates which alarms changed.</description></item>
+///         <item><description><c>GetAlarmExtendedRec(index, out AlarmRecord)</c> — pulls the full alarm record (operator, comment, original raise, category, severity).</description></item>
+///         <item><description><c>AlarmAckByGUID(alarmGuid, ackComment, oprName, oprNode, oprDomain, oprFullName)</c> — full-fidelity native Acknowledge: comment + four operator-identity fields are atomic with the ack transition.</description></item>
 ///     </list>
 ///     <para>
-///         Until that decision is made, this sink's <see cref="Attach"/> is a
-///         no-op. The worker continues to function for data subscriptions, and
-///         the gateway's <see cref="MxEventFamily.OnAlarmTransition"/> family
-///         is reserved on the wire but never emitted. lmxopcua-side
-///         <c>AlarmConditionService</c> keeps the sub-attribute synthesis
-///         active and continues to surface alarms to OPC UA Part 9 clients.
+///         <strong>Wiring plan (subsequent PRs):</strong>
+///     </para>
+///     <list type="number">
+///         <item><description>Worker session-startup wires <c>AlarmClient.RegisterConsumer</c> against the worker's existing STA hWnd; <c>Subscribe</c> with the Galaxy provider name + a permissive priority/filter range.</description></item>
+///         <item><description>The STA's WM_APP handler routes alarm-changed messages into <see cref="EnqueueTransition"/>; the message ID is established at runtime via the consumer's reported handler (verify on dev rig).</description></item>
+///         <item><description>Gateway-side <c>AcknowledgeAlarm</c> RPC translates to a worker command that calls <c>AlarmClient.AlarmAckByGUID</c> with the OPC UA operator's resolved identity — replaces the worker-pending diagnostic from PR A.3.</description></item>
+///     </list>
+///     <para>
+///         Until those PRs land, <see cref="Attach"/> is a no-op. The worker
+///         continues to function for data subscriptions, and the gateway's
+///         <see cref="MxEventFamily.OnAlarmTransition"/> family is reserved on
+///         the wire but never emitted. lmxopcua-side <c>AlarmConditionService</c>
+///         keeps the sub-attribute synthesis active and continues to surface
+///         alarms to OPC UA Part 9 clients in the meantime.
 ///     </para>
 /// </remarks>
 public sealed class MxAccessAlarmEventSink : IMxAccessEventSink

src/MxGateway.Worker/MxGateway.Worker.csproj

@@ -24,6 +24,11 @@
       <Private>false</Private>
       <SpecificVersion>false</SpecificVersion>
     </Reference>
+    <Reference Include="aaAlarmManagedClient">
+      <HintPath>C:\Program Files (x86)\ArchestrA\Framework\Bin\ViewAppFramework\Content\MA\aaAlarmManagedClient.dll</HintPath>
+      <Private>false</Private>
+      <SpecificVersion>false</SpecificVersion>
+    </Reference>
   </ItemGroup>
 
 </Project>