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

tests/ScadaLink.InboundAPI.Tests/Middleware/AuditWriteMiddlewareTests.cs

@@ -350,6 +350,46 @@ public class AuditWriteMiddlewareTests
         Assert.Equal(requestJson, evt.RequestSummary);
     }
 
+    // ---------------------------------------------------------------------
+    // Correlation id — Audit Log #23: each inbound row carries a fresh
+    // per-request correlation id so inbound rows are correlatable.
+    // ---------------------------------------------------------------------
+
+    [Fact]
+    public async Task InboundRow_CarriesNonNull_CorrelationId()
+    {
+        var writer = new RecordingAuditWriter();
+        var ctx = BuildContext();
+        var mw = CreateMiddleware(_ =>
+        {
+            ctx.Response.StatusCode = 200;
+            return Task.CompletedTask;
+        }, writer);
+
+        await mw.InvokeAsync(ctx);
+
+        var evt = Assert.Single(writer.Events);
+        Assert.NotNull(evt.CorrelationId);
+        Assert.NotEqual(Guid.Empty, evt.CorrelationId!.Value);
+    }
+
+    [Fact]
+    public async Task SeparateRequests_GetDistinct_CorrelationIds()
+    {
+        var writer = new RecordingAuditWriter();
+        var mw = CreateMiddleware(hc =>
+        {
+            hc.Response.StatusCode = 200;
+            return Task.CompletedTask;
+        }, writer);
+
+        await mw.InvokeAsync(BuildContext());
+        await mw.InvokeAsync(BuildContext());
+
+        Assert.Equal(2, writer.Events.Count);
+        Assert.NotEqual(writer.Events[0].CorrelationId, writer.Events[1].CorrelationId);
+    }
+
     [Fact]
     public async Task DurationMs_IsRecorded()
     {