Phase 3 PR 36 — AVEVA prerequisites test-support library. New tests/ZB.MOM.WW.OtOpcUa.Driver.Galaxy.TestSupport multi-targeted class library (net10.0 + net48 so both the modern and the MXAccess-COM x86 test projects can consume it) that probes every piece of the AVEVA System Platform + OtOpcUa stack a live-Galaxy test depends on and returns a structured PrerequisiteReport. Closes the gap where live-smoke tests silently returned 'unreachable' without telling operators which specific piece failed.

AvevaPrerequisites.CheckAllAsync walks eight probe categories producing PrerequisiteCheck rows each with Name (e.g. 'service:aaBootstrap', 'sql:ZB', 'com:LMXProxy', 'registry:ArchestrA.Framework'), Category (AvevaCoreService / AvevaSoftService / AvevaInstall / MxAccessCom / GalaxyRepository / AvevaHistorian / OtOpcUaService / Environment), Status (Pass / Warn / Fail / Skip), and operator-facing Detail message. Report aggregates them: IsLivetestReady (no Fails anywhere) and IsAvevaSideReady (AVEVA-side categories pass, our v2 services can be absent while still considering the environment AVEVA-ready) so different test tiers can use the right threshold.
Individual probes: ServiceProbe.Check queries the Windows Service Control Manager via System.ServiceProcess.ServiceController — treats DemandStart+Stopped as Warn (NmxSvc is DemandStart by design; master pulls it up) but AutoStart+Stopped as Fail; not-installed is Fail for hard-required services, Warn for soft ones; non-Windows hosts get Skip; transitional states like StartPending get Warn with a 'try again' hint. RegistryProbe reads HKLM\SOFTWARE\WOW6432Node\ArchestrA\{Framework,Framework\Platform,MSIInstall} — Framework key presence + populated InstallPath/RootPath values mean System Platform installed; PfeConfigOptions in the Platform subkey (format 'PlatformId=N,EngineId=N,...') indicates a Platform has been deployed from the IDE (PlatformId=0 means never deployed — MXAccess will connect but every subscription will be Bad quality); RebootRequired='True' under MSIInstall surfaces as a loud warn since post-patch behavior is undefined. MxAccessComProbe resolves the LMXProxy.LMXProxyServer ProgID → CLSID → HKLM\SOFTWARE\Classes\WOW6432Node\CLSID\{guid}\InprocServer32, verifying the registered file exists on disk (catches the orphan-registry case where a previous uninstall left the ProgID registered but the DLL is gone — distinguishes it from the 'totally not installed' case by message); also emits a Warn when the test process is 64-bit (MXAccess COM activation fails with REGDB_E_CLASSNOTREG 0x80040154 regardless of registration, so seeing this warning tells operators why the activation would fail even on a fully-installed machine). SqlProbe tests Galaxy Repository via Microsoft.Data.SqlClient using the Windows-auth localhost connection string the repo code defaults to — distinguishes 'SQL Server unreachable' (connection fails) from 'ZB database does not exist' (SELECT DB_ID('ZB') returns null) because they have different remediation paths (sc.exe start MSSQLSERVER vs. restore from .cab backup); a secondary CheckDeployedObjectCountAsync query on 'gobject WHERE deployed_version > 0' warns when the count is zero because discovery smoke tests will return empty hierarchies. NamedPipeProbe opens a 2s NamedPipeClientStream against OtOpcUaGalaxyHost's pipe ('OtOpcUaGalaxy' per the installer default) — pipe accepting a connection proves the Host service is listening; disconnects immediately so we don't consume a session slot.
Service lists kept as internal static data so tests can inspect + override: CoreServices (aaBootstrap + aaGR + NmxSvc + MSSQLSERVER — hard fail if missing), SoftServices (aaLogger + aaUserValidator + aaGlobalDataCacheMonitorSvr — warn only; stack runs without them but diagnostics/auth are degraded), HistorianServices (aahClientAccessPoint + aahGateway — opt-in via Options.CheckHistorian, only matters for HistoryRead IPC paths), OtOpcUaServices (our OtOpcUaGalaxyHost hard-required for end-to-end live tests + OtOpcUa warn + GLAuth warn). Narrower entry points CheckRepositoryOnlyAsync and CheckGalaxyHostPipeOnlyAsync for tests that only care about specific subsystems — avoid paying the full probe cost on every GalaxyRepositoryLiveSmokeTests fact.
Multi-targeting mechanics: System.ServiceProcess.ServiceController + Microsoft.Win32.Registry are NuGet packages on net10 but in-box BCL references on net48; csproj conditions Package vs Reference by TargetFramework. Microsoft.Data.SqlClient v6 supports both frameworks so single PackageReference. Net48Polyfills.cs provides IsExternalInit shim (records/init-only setters) and SupportedOSPlatformAttribute stub so the same Probe sources compile on both frameworks without per-callsite preprocessor guards — lets Roslyn's platform-compatibility analyzer stay useful on net10 without breaking net48 builds.
Existing GalaxyRepositoryLiveSmokeTests updated to delegate its skip decision to AvevaPrerequisites.CheckRepositoryOnlyAsync (legacy ZbReachableAsync kept as a compatibility adapter so the in-test 'if (!await ZbReachableAsync()) return;' pattern keeps working while the surrounding fixtures gradually migrate to Assert.Skip-with-reason). Slnx file registers the new project.
Tests — AvevaPrerequisitesLiveTests (8 new Integration cases, Category=LiveGalaxy): the helper correctly reports Framework install (registry pass), aaBootstrap Running (service pass), aaGR Running (service pass), MxAccess COM registered (com pass), ZB database reachable (sql pass), deployed-object count > 0 (warn-upgraded-to-pass because this box has 49 objects deployed), the AVEVA side is ready even when our own services (OtOpcUaGalaxyHost) aren't installed yet (IsAvevaSideReady=true), and the helper emits rows for OtOpcUaGalaxyHost + OtOpcUa + GLAuth even when not installed (regression guard — nobody can accidentally ship a check that omits our own services). Full Galaxy.Host.Tests Category=LiveGalaxy suite: 13 pass (5 prior smoke + 8 new prerequisites). Full solution build clean, 0 errors.
What's NOT in this PR: end-to-end Galaxy stack smoke (Proxy → Host pipe → MXAccess → real Galaxy tag). That's the next PR — this one is the gate the end-to-end smoke will call first to produce actionable skip messages instead of silent returns.

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

tests/ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Host.Tests/GalaxyRepositoryLiveSmokeTests.cs

@@ -6,6 +6,7 @@ using Xunit;
 using ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Host.Backend;
 using ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Host.Backend.Galaxy;
 using ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Shared.Contracts;
+using ZB.MOM.WW.OtOpcUa.Driver.Galaxy.TestSupport;
 
 namespace ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Host.Tests
 {
@@ -16,6 +17,11 @@ namespace ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Host.Tests
     ///     SQL the v1 Host uses, proving the lift is byte-for-byte equivalent at the
     ///     <c>DiscoverHierarchyResponse</c> shape.
     /// </summary>
+    /// <remarks>
+    ///     Since PR 36, skip logic is delegated to <see cref="AvevaPrerequisites.CheckRepositoryOnlyAsync"/>
+    ///     so operators see exactly why a test skipped ("ZB db not found" vs "SQL Server
+    ///     unreachable") instead of a silent return.
+    /// </remarks>
     [Trait("Category", "LiveGalaxy")]
     public sealed class GalaxyRepositoryLiveSmokeTests
     {
@@ -26,15 +32,20 @@ namespace ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Host.Tests
             CommandTimeoutSeconds = 10,
         };
 
+        private static async Task<string?> RepositorySkipReasonAsync()
+        {
+            using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(4));
+            var report = await AvevaPrerequisites.CheckRepositoryOnlyAsync(
+                DevZbOptions().ConnectionString, cts.Token);
+            return report.SkipReason;
+        }
+
         private static async Task<bool> ZbReachableAsync()
         {
-            try
-            {
-                var repo = new GalaxyRepository(DevZbOptions());
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(3));
-                return await repo.TestConnectionAsync(cts.Token);
-            }
-            catch { return false; }
+            // Legacy silent-skip adapter — keeps the existing tests compiling while
+            // gradually migrating to the Skip-with-reason pattern. Returns true when the
+            // prerequisite check has no Fail entries.
+            return (await RepositorySkipReasonAsync()) is null;
         }
 
         [Fact]