fix: serialize database activity during playout

tests/MBN_STOCK_WEBVIEW.Infrastructure.Tests/DatabaseHealthServiceTests.cs

@@ -17,6 +17,8 @@ public sealed class DatabaseHealthServiceTests
         Assert.Equal(DatabaseHealthState.NotConfigured, status.State);
         Assert.Equal(DataSourceKind.Oracle, status.Source);
         Assert.Equal(TimeSpan.Zero, status.Elapsed);
+        Assert.Null(status.IsTransient);
+        Assert.Null(status.ProviderErrorCode);
         Assert.Equal(0, executor.CallCount);
     }
 
@@ -37,6 +39,8 @@ public sealed class DatabaseHealthServiceTests
 
         Assert.Equal(DatabaseHealthState.Healthy, status.State);
         Assert.Equal(source, status.Source);
+        Assert.Null(status.IsTransient);
+        Assert.Null(status.ProviderErrorCode);
         Assert.Equal(1, executor.CallCount);
         Assert.Equal(expectedQuery, executor.LastQuery);
     }
@@ -48,7 +52,10 @@ public sealed class DatabaseHealthServiceTests
         var executor = new StubDataQueryExecutor
         {
             ExecuteAsyncHandler = (_, _, _, _) => Task.FromException<DataTable>(
-                new DatabaseQueryException(DataSourceKind.MariaDb, isTransient: true))
+                new DatabaseQueryException(
+                    DataSourceKind.MariaDb,
+                    isTransient: true,
+                    providerErrorCode: 1042))
         };
         var service = new DatabaseHealthService(executor, TestOptions.CreateConfigured());
 
@@ -56,6 +63,8 @@ public sealed class DatabaseHealthServiceTests
 
         Assert.Equal(DatabaseHealthState.Unhealthy, status.State);
         Assert.Equal(DataSourceKind.MariaDb, status.Source);
+        Assert.True(status.IsTransient);
+        Assert.Equal(1042, status.ProviderErrorCode);
         Assert.DoesNotContain(host, status.UserMessage, StringComparison.Ordinal);
     }
 
@@ -73,6 +82,25 @@ public sealed class DatabaseHealthServiceTests
 
         Assert.Equal(DatabaseHealthState.TimedOut, status.State);
         Assert.Equal(DataSourceKind.Oracle, status.Source);
+        Assert.True(status.IsTransient);
+        Assert.Null(status.ProviderErrorCode);
+    }
+
+    [Fact]
+    public async Task CheckAsync_NonOperationInfrastructureFailure_DoesNotInventDiagnostics()
+    {
+        var executor = new StubDataQueryExecutor
+        {
+            ExecuteAsyncHandler = (_, _, _, _) => Task.FromException<DataTable>(
+                new DatabaseConfigurationException("safe configuration failure"))
+        };
+        var service = new DatabaseHealthService(executor, TestOptions.CreateConfigured());
+
+        var status = await service.CheckAsync(DataSourceKind.Oracle);
+
+        Assert.Equal(DatabaseHealthState.Unhealthy, status.State);
+        Assert.Null(status.IsTransient);
+        Assert.Null(status.ProviderErrorCode);
     }
 }
 

tests/Web/playout-safety.test.cjs

@@ -132,6 +132,15 @@ test("A database refresh fault clears only after TAKE OUT resets refresh state",
   assert.equal(safety.shouldClearRefreshError(unrelated, false), false);
 });
 
+test("Database health snapshots accept only a strictly increasing native sequence", () => {
+  assert.equal(safety.isNewerDatabaseStatusSequence(0, 1), true);
+  assert.equal(safety.isNewerDatabaseStatusSequence(7, 8), true);
+  assert.equal(safety.isNewerDatabaseStatusSequence(7, 7), false);
+  assert.equal(safety.isNewerDatabaseStatusSequence(7, 6), false);
+  assert.equal(safety.isNewerDatabaseStatusSequence(7, "8"), false);
+  assert.equal(safety.isNewerDatabaseStatusSequence(7, null), false);
+});
+
 test("Stored conditional aliases preserve the exact builder owner", () => {
   const catalog = [
     { builderKey: "s5032", code: "5032", aliases: ["5032", "8018", "8032"] },