diff --git a/src/ZB.MOM.WW.ScadaBridge.InboundAPI/EndpointExtensions.cs b/src/ZB.MOM.WW.ScadaBridge.InboundAPI/EndpointExtensions.cs
index abb6e0cd..4776b8dd 100644
--- a/src/ZB.MOM.WW.ScadaBridge.InboundAPI/EndpointExtensions.cs
+++ b/src/ZB.MOM.WW.ScadaBridge.InboundAPI/EndpointExtensions.cs
@@ -275,7 +275,10 @@ public static class EndpointExtensions
 
         var scriptResult = await executor.ExecuteAsync(
             method, paramResult.Parameters, routeHelper, timeout,
-            httpContext.RequestAborted, parentExecutionId);
+            httpContext.RequestAborted, parentExecutionId,
+            // Flow Debugger (design 2026-09-05 §5.2): a method flagged TraceAllCalls traces every
+            // production call so Replay of a real integration call is complete.
+            trace: method.TraceAllCalls);
 
         if (!scriptResult.Success)
         {
diff --git a/src/ZB.MOM.WW.ScadaBridge.InboundAPI/InboundScriptExecutor.cs b/src/ZB.MOM.WW.ScadaBridge.InboundAPI/InboundScriptExecutor.cs
index f63292fb..4359cef2 100644
--- a/src/ZB.MOM.WW.ScadaBridge.InboundAPI/InboundScriptExecutor.cs
+++ b/src/ZB.MOM.WW.ScadaBridge.InboundAPI/InboundScriptExecutor.cs
@@ -330,7 +330,10 @@ public class InboundScriptExecutor
         // Deliberate ordering: this optional parameter trails the CancellationToken
         // because it was appended additively for non-breaking contract evolution.
         // Every call site passes it by named argument (parentExecutionId:).
-        Guid? parentExecutionId = null)
+        Guid? parentExecutionId = null,
+        // Flow Debugger (design 2026-09-05 §5.2): trace the routed site runs this method makes.
+        // Additive; the endpoint passes ApiMethod.TraceAllCalls, the Flow Debugger passes true.
+        bool trace = false)
     {
         // Keep the timeout source and the request-abort source
         // separable. A single linked CTS makes a genuine client disconnect
@@ -396,7 +399,8 @@ public class InboundScriptExecutor
                 parameters,
                 route.WithDeadline(cts.Token)
                      .WithRequestAborted(cancellationToken)
-                     .WithParentExecutionId(parentExecutionId),
+                     .WithParentExecutionId(parentExecutionId)
+                     .WithTrace(trace),
                 dbHelper,
                 cts.Token);
 
diff --git a/tests/ZB.MOM.WW.ScadaBridge.InboundAPI.Tests/InboundScriptExecutorTests.cs b/tests/ZB.MOM.WW.ScadaBridge.InboundAPI.Tests/InboundScriptExecutorTests.cs
index 2334d070..f81573f1 100644
--- a/tests/ZB.MOM.WW.ScadaBridge.InboundAPI.Tests/InboundScriptExecutorTests.cs
+++ b/tests/ZB.MOM.WW.ScadaBridge.InboundAPI.Tests/InboundScriptExecutorTests.cs
@@ -28,6 +28,35 @@ public class InboundScriptExecutorTests
         _route = new RouteHelper(locator, router);
     }
 
+    [Fact]
+    public async Task ExecuteAsync_TraceFlag_ReachesTheRoutedCallRequest()
+    {
+        // Flow Debugger (design 2026-09-05 §5.2): ExecuteAsync(trace: true) builds the script's
+        // Route helper WithTrace(true), so a Route.To(...).Call(...) inside the script sends a
+        // traced RouteToCallRequest; the default stays untraced.
+        var locator = Substitute.For<IInstanceLocator>();
+        var router = Substitute.For<IInstanceRouter>();
+        locator.GetSiteIdForInstanceAsync("inst", Arg.Any<CancellationToken>()).Returns("SiteA");
+        var captured = new List<RouteToCallRequest>();
+        router.RouteToCallAsync("SiteA", Arg.Do<RouteToCallRequest>(captured.Add), Arg.Any<CancellationToken>())
+            .Returns(ci => new RouteToCallResponse(((RouteToCallRequest)ci[1]).CorrelationId, true, 1, null, DateTimeOffset.UtcNow));
+        var route = new RouteHelper(locator, router);
+        var method = new ApiMethod("routed", "x") { Id = 9, TimeoutSeconds = 10 };
+        _executor.RegisterHandler("routed", ctx => ctx.Route.To("inst").Call("work"));
+
+        var parent = Guid.NewGuid();
+        var traced = await _executor.ExecuteAsync(method, new Dictionary<string, object?>(), route,
+            TimeSpan.FromSeconds(10), parentExecutionId: parent, trace: true);
+        var plain = await _executor.ExecuteAsync(method, new Dictionary<string, object?>(), route, TimeSpan.FromSeconds(10));
+
+        Assert.True(traced.Success, traced.ErrorMessage);
+        Assert.True(plain.Success, plain.ErrorMessage);
+        Assert.Equal(2, captured.Count);
+        Assert.True(captured[0].Trace);
+        Assert.Equal(parent, captured[0].ParentExecutionId);
+        Assert.False(captured[1].Trace);
+    }
+
     [Fact]
     public async Task RegisteredHandler_ExecutesSuccessfully()
     {