fix: wait for AutoCAD command-queue readiness barrier

Plant3D2026/P_Rec_Annot/src/PRecAnnot.Plant3D2026/EntryPoint.cs

@@ -50,6 +50,12 @@ public sealed class EntryPoint : IExtensionApplication
     [CommandMethod("PHP_REC_AUTOMATION_START", CommandFlags.Session)]
     public void AutomationStartCommand() => FirstLimitedApplyAutomationBootstrap.Arm();
 
+    // Test-only command-queue barrier. It deliberately performs no Plant or
+    // drawing work; its CommandEnded event proves the activated document is
+    // ready before the coordinator calls the Plant APIs.
+    [CommandMethod("PHP_REC_AUTOMATION_READY")]
+    public void AutomationReadyCommand() { }
+
     private static void RunDiagnostic(string commandName)
     {
         var operationId = Guid.NewGuid().ToString("N");

Plant3D2026/P_Rec_Annot/src/PRecAnnot.Plant3D2026/FirstLimitedApplyAutomation.cs

@@ -204,7 +204,7 @@ internal sealed class FirstLimitedApplyAutomationCoordinator
             {
                 fixtureDocumentActivated = true;
                 transitions.Add("FixtureDocumentActiveAfterOpen");
-                TryActivateProjectAndVerifyContext();
+                QueueReadinessBarrier();
             }
         }
         catch (System.Exception ex) { FailFromCallback("Start", ex, "AUTOMATION_START_FAILED"); }
@@ -270,11 +270,23 @@ internal sealed class FirstLimitedApplyAutomationCoordinator
         transitions.Add("CommandQueued:" + command);
         document.SendStringToExecute(command + " ", true, false, false);
     }
+    private void QueueReadinessBarrier()
+    {
+        if (IsTerminal || document is null) return;
+        transitions.Add("ReadinessBarrierQueued");
+        document.SendStringToExecute("PHP_REC_AUTOMATION_READY ", true, false, false);
+    }
     private void OnCommandEnded(object sender, CommandEventArgs e)
     {
         RunCallback("CommandEnded", () =>
         {
             var name = e.GlobalCommandName?.Trim().TrimStart('.', '_').ToUpperInvariant();
+            if (name == "PHP_REC_AUTOMATION_READY")
+            {
+                transitions.Add("ReadinessBarrierCompleted");
+                TryActivateProjectAndVerifyContext();
+                return;
+            }
             if (name is not ("PXP-OA" or "UNDO" or "U")) return;
             completed.Add(name);
             transitions.Add("CommandCompleted:" + name);

Plant3D2026/P_Rec_Annot/tests/PRecAnnot.Core.Tests/FoundationTests.cs

@@ -61,6 +61,7 @@ public sealed class FoundationTests
         Assert.Contains("[CommandMethod(\"PHP_REC_ANNOT\")]", source);
         Assert.Contains("[CommandMethod(\"PXP-AAV\")]", source);
         Assert.Contains("[CommandMethod(\"PXP-OA\")]", source);
+        Assert.Contains("PHP_REC_AUTOMATION_READY", source);
     }
 
     [Fact] public void AutomationBootstrap_DefersPlantAndDocumentAccessUntilCoordinator()
@@ -104,7 +105,9 @@ public sealed class FoundationTests
         var start = source[source.IndexOf("public void Start()", StringComparison.Ordinal)..source.IndexOf("private void CompleteLifecycleProbe", StringComparison.Ordinal)];
         Assert.Contains("FixtureDocumentActiveAfterOpen", start);
         Assert.Contains("string.Equals(activeDocument.Name, document.Name", start);
-        Assert.Contains("TryActivateProjectAndVerifyContext();", start);
+        Assert.Contains("QueueReadinessBarrier();", start);
+        Assert.Contains("ReadinessBarrierCompleted", source);
+        Assert.Contains("TryActivateProjectAndVerifyContext();", source);
     }
 
     [Fact] public void AutomationControlledExit_QueuesNativeQuitAfterPublicCommand()