fix(config-db): EnableRetryOnFailure fleet-wide + execution-strategy wrap of the combined-telemetry dual-write

Installs SqlServerRetryingExecutionStrategy (5 retries, 30s cap) so transient SQL
faults retry transparently on every read-side path. Manual transactions aren't
auto-retried, so AuditLogIngestActor's idempotent dual-write is wrapped in an
explicit CreateExecutionStrategy().ExecuteAsync to become retriable. Verified
empirically that existing manual transactions (BundleImporter) are unaffected —
EF skips the strategy while a transaction is already active.

src/ZB.MOM.WW.ScadaBridge.AuditLog/Central/AuditLogIngestActor.cs

@@ -1,4 +1,5 @@
 using Akka.Actor;
+using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
 using ZB.MOM.WW.Audit;
@@ -259,37 +260,51 @@ public class AuditLogIngestActor : ReceiveActor
             // skip the registration.
             var failureCounter = scope.ServiceProvider.GetService<ICentralAuditWriteFailureCounter>();
 
+            // Task 12 (arch-review 04 S5): retry the dual-write under the DbContext's
+            // configured resiliency strategy. A manual (user-initiated) transaction is
+            // NOT auto-retried by EnableRetryOnFailure — EF executes directly while a
+            // transaction is active — so the whole { BEGIN; insert; upsert; COMMIT }
+            // unit is wrapped here to become a single retriable operation. The unit is
+            // idempotent (InsertIfNotExists on EventId + monotonic upsert on
+            // TrackedOperationId), so replay after a rolled-back transient failure is
+            // safe. NoOpExecutionStrategy on non-configured/test contexts runs it once.
+            var strategy = dbContext.Database.CreateExecutionStrategy();
+
             foreach (var entry in cmd.Entries)
             {
                 try
                 {
-                    await using var tx = await dbContext.Database
+                    await strategy.ExecuteAsync(async () =>
-                        .BeginTransactionAsync()
+                    {
-                        .ConfigureAwait(false);
+                        await using var tx = await dbContext.Database
+                            .BeginTransactionAsync()
+                            .ConfigureAwait(false);
 
-                    // Stamp IngestedAtUtc on both rows from a single
+                        // Stamp IngestedAtUtc on both rows from a single
-                    // central-side instant so a join on the two tables sees
+                        // central-side instant so a join on the two tables sees
-                    // matching timestamps (debugging convenience, not a
+                        // matching timestamps (debugging convenience, not a
-                    // correctness invariant).
+                        // correctness invariant).
-                    var ingestedAt = DateTime.UtcNow;
+                        var ingestedAt = DateTime.UtcNow;
-                    // Redact the audit half BEFORE the dual-write — only the
+                        // Redact the audit half BEFORE the dual-write — only the
-                    // AuditLog row's payload columns are redactable; SiteCalls
+                        // AuditLog row's payload columns are redactable; SiteCalls
-                    // carries operational state only (status, retry count) and
+                        // carries operational state only (status, retry count) and
-                    // is left untouched. Null redactor falls back
+                        // is left untouched. Null redactor falls back
-                    // to SafeDefault so header redaction always runs.
+                        // to SafeDefault so header redaction always runs.
-                    // IngestedAtUtc is a DetailsJson field
+                        // IngestedAtUtc is a DetailsJson field
-                    // on the canonical record, so stamp it via the projection helper.
+                        // on the canonical record, so stamp it via the projection helper.
-                    var safeRedactor = redactor ?? SafeDefaultAuditRedactor.Instance;
+                        var safeRedactor = redactor ?? SafeDefaultAuditRedactor.Instance;
-                    var filteredAudit = safeRedactor.Apply(entry.Audit);
+                        var filteredAudit = safeRedactor.Apply(entry.Audit);
-                    var auditStamped = AuditRowProjection.WithIngestedAtUtc(filteredAudit, ingestedAt);
+                        var auditStamped = AuditRowProjection.WithIngestedAtUtc(filteredAudit, ingestedAt);
-                    var siteCallStamped = entry.SiteCall with { IngestedAtUtc = ingestedAt };
+                        var siteCallStamped = entry.SiteCall with { IngestedAtUtc = ingestedAt };
 
-                    await auditRepo.InsertIfNotExistsAsync(auditStamped)
+                        await auditRepo.InsertIfNotExistsAsync(auditStamped)
-                        .ConfigureAwait(false);
+                            .ConfigureAwait(false);
-                    await siteCallRepo.UpsertAsync(siteCallStamped)
+                        await siteCallRepo.UpsertAsync(siteCallStamped)
-                        .ConfigureAwait(false);
+                            .ConfigureAwait(false);
+
+                        await tx.CommitAsync().ConfigureAwait(false);
+                    }).ConfigureAwait(false);
 
-                    await tx.CommitAsync().ConfigureAwait(false);
                     accepted.Add(entry.Audit.EventId);
                 }
                 catch (Exception ex)

src/ZB.MOM.WW.ScadaBridge.ConfigurationDatabase/Repositories/AuditLogRepository.cs

@@ -229,6 +229,13 @@ VALUES
     /// <inheritdoc />
     public async Task<long> SwitchOutPartitionAsync(DateTime monthBoundary, TimeSpan? commandTimeout = null, CancellationToken ct = default)
     {
+        // Task 12 (arch-review 04 S5) note: the drop-and-rebuild batch below runs via
+        // ExecuteSqlRaw with NO EF user-transaction — it carries its own server-side
+        // BEGIN TRANSACTION / TRY-CATCH / ROLLBACK — so the DbContext's retrying
+        // execution strategy (EnableRetryOnFailure) MAY auto-replay the whole batch on
+        // a transient fault. That replay is safe: every step is IF-EXISTS / IF-NOT-EXISTS
+        // guarded and the staging table is GUID-suffixed, so a re-run is idempotent.
+        //
         // Maintenance timeout in whole seconds (ADO.NET CommandTimeout unit). Null leaves the
         // provider default in place. See AuditLogPurgeOptions.MaintenanceCommandTimeoutMinutes /
         // arch-review 04 S2 for why the ~30s default is unsafe for the switch-out dance.

src/ZB.MOM.WW.ScadaBridge.ConfigurationDatabase/ServiceCollectionExtensions.cs

@@ -28,7 +28,22 @@ public static class ServiceCollectionExtensions
         // CreateProtector during model building.
         services.AddDbContext<ScadaBridgeDbContext>((serviceProvider, options) =>
         {
-            options.UseSqlServer(connectionString)
+            options.UseSqlServer(
+                    connectionString,
+                    // Task 12 (arch-review 04 S5): connection resiliency. A transient
+                    // SQL fault (failover, throttling, dropped connection) previously
+                    // surfaced raw to every read-side caller — KPI asks, outbox
+                    // queries, Tracking.Status, execution-tree walks. EnableRetryOnFailure
+                    // installs the SqlServerRetryingExecutionStrategy so those retry
+                    // transparently. Note: manual (user-initiated) transactions are NOT
+                    // auto-retried — EF executes them directly while a transaction is
+                    // active — so the combined-telemetry dual-write is wrapped in an
+                    // explicit CreateExecutionStrategy() to become retriable (see
+                    // AuditLogIngestActor.OnCachedTelemetryAsync).
+                    sql => sql.EnableRetryOnFailure(
+                        maxRetryCount: 5,
+                        maxRetryDelay: TimeSpan.FromSeconds(30),
+                        errorNumbersToAdd: null))
                 .ConfigureWarnings(w => w.Ignore(
                     Microsoft.EntityFrameworkCore.Diagnostics.RelationalEventId.PendingModelChangesWarning));
         });

tests/ZB.MOM.WW.ScadaBridge.ConfigurationDatabase.Tests/ServiceCollectionExtensionsTests.cs

@@ -1,4 +1,5 @@
 using System.Reflection;
+using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.DependencyInjection;
 using ZB.MOM.WW.ScadaBridge.Commons.Interfaces.Repositories;
 using ZB.MOM.WW.ScadaBridge.Commons.Interfaces.Services;
@@ -13,7 +14,7 @@ public class ServiceCollectionExtensionsTests
     {
         var services = new ServiceCollection();
 
-        services.AddConfigurationDatabase("DataSource=:memory:");
+        services.AddConfigurationDatabase("Server=unused;Database=unused;");
 
         Assert.Contains(services, d => d.ServiceType == typeof(ITemplateEngineRepository));
         Assert.Contains(services, d => d.ServiceType == typeof(IAuditService));
@@ -21,6 +22,32 @@ public class ServiceCollectionExtensionsTests
         Assert.Contains(services, d => d.ServiceType == typeof(IAuditLogRepository));
     }
 
+    [Fact]
+    public void AddConfigurationDatabase_Configures_RetryingExecutionStrategy()
+    {
+        // Task 12 (arch-review 04 S5): the central DbContext must survive transient
+        // SQL faults. EnableRetryOnFailure installs a non-null ExecutionStrategyFactory
+        // on the SqlServer options extension — covering every read-side path (KPI asks,
+        // outbox queries, Tracking.Status, execution trees) that previously surfaced
+        // transient faults raw.
+        var services = new ServiceCollection();
+        services.AddConfigurationDatabase("Server=unused;Database=unused;");
+        using var sp = services.BuildServiceProvider();
+
+        var options = sp.GetRequiredService<DbContextOptions<ScadaBridgeDbContext>>();
+
+        // EF1001: SqlServerOptionsExtension is an internal EF surface, but it is the
+        // only place the retrying-strategy factory is observable — asserting it is the
+        // point of this test. Scoped suppression, not a project-wide one.
+#pragma warning disable EF1001
+        var sqlExt = options.Extensions
+            .OfType<Microsoft.EntityFrameworkCore.SqlServer.Infrastructure.Internal.SqlServerOptionsExtension>()
+            .Single();
+
+        Assert.NotNull(sqlExt.ExecutionStrategyFactory);
+#pragma warning restore EF1001
+    }
+
     // The no-arg overload is [Obsolete(error: true)], so it cannot be referenced directly
     // from source — that is the compile-time guard. Invoke it via reflection to verify the
     // runtime defence-in-depth behaviour.