feat(auditlog): per-script-execution correlation id on sync audit rows

tests/ScadaLink.SiteRuntime.Tests/Scripts/DatabaseSyncEmissionTests.cs

@@ -48,14 +48,28 @@ public class DatabaseSyncEmissionTests
     private const string SourceScript = "ScriptActor:Sync";
     private const string ConnectionName = "machineData";
 
+    /// <summary>
+    /// Audit Log #23: a fixed execution-wide correlation id used by the
+    /// default <see cref="CreateHelper(IDatabaseGateway, IAuditWriter?)"/>
+    /// overload so assertions can compare against a known value.
+    /// </summary>
+    private static readonly Guid TestCorrelationId = Guid.NewGuid();
+
     private static ScriptRuntimeContext.DatabaseHelper CreateHelper(
         IDatabaseGateway gateway,
         IAuditWriter? auditWriter)
+        => CreateHelper(gateway, auditWriter, TestCorrelationId);
+
+    private static ScriptRuntimeContext.DatabaseHelper CreateHelper(
+        IDatabaseGateway gateway,
+        IAuditWriter? auditWriter,
+        Guid correlationId)
     {
         return new ScriptRuntimeContext.DatabaseHelper(
             gateway,
             InstanceName,
             NullLogger.Instance,
+            correlationId,
             auditWriter: auditWriter,
             siteId: SiteId,
             sourceScript: SourceScript,
@@ -268,10 +282,34 @@ public class DatabaseSyncEmissionTests
         Assert.Equal(SourceScript, evt.SourceScript);
         // Outbound channel: Actor carries the calling script identity.
         Assert.Equal(SourceScript, evt.Actor);
-        Assert.Null(evt.CorrelationId);
+        // Audit Log #23: the sync DbWrite row now carries the execution-wide
+        // correlation id the helper was constructed with.
+        Assert.Equal(TestCorrelationId, evt.CorrelationId);
         Assert.NotEqual(Guid.Empty, evt.EventId);
     }
 
+    [Fact]
+    public async Task SyncDbWrite_StampsExecutionCorrelationId()
+    {
+        using var keepAlive = new SqliteConnection("Data Source=kc;Mode=Memory;Cache=Shared");
+        var inner = NewInMemoryDb(out var _);
+        var gateway = new Mock<IDatabaseGateway>();
+        gateway
+            .Setup(g => g.GetConnectionAsync(ConnectionName, It.IsAny<CancellationToken>()))
+            .ReturnsAsync(inner);
+        var writer = new CapturingAuditWriter();
+        var correlationId = Guid.NewGuid();
+
+        var helper = CreateHelper(gateway.Object, writer, correlationId);
+        await using var conn = await helper.Connection(ConnectionName);
+        await using var cmd = conn.CreateCommand();
+        cmd.CommandText = "INSERT INTO t (id, name) VALUES (7, 'eta')";
+        await cmd.ExecuteNonQueryAsync();
+
+        var evt = Assert.Single(writer.Events);
+        Assert.Equal(correlationId, evt.CorrelationId);
+    }
+
     [Fact]
     public async Task DurationMs_NonZero()
     {