fix(siteruntime): faulted expression-eval task clears _evalInFlight instead of killing the ScriptActor trigger (plan R2-03 T2)

src/ZB.MOM.WW.ScadaBridge.SiteRuntime/Actors/ScriptActor.cs

@@ -159,6 +159,10 @@ public class ScriptActor : ReceiveActor, IWithTimers
 
         // Handle the off-dispatcher trigger-expression evaluation result (P1).
         Receive<ExpressionEvalResult>(HandleExpressionEvalResult);
+
+        // Handle a faulted off-dispatcher evaluation task (N2) — clears in-flight
+        // instead of stranding the trigger with an unhandled Status.Failure.
+        Receive<ExpressionEvalFailed>(HandleExpressionEvalFailed);
     }
 
     /// <inheritdoc />
@@ -310,7 +314,8 @@ public class ScriptActor : ReceiveActor, IWithTimers
             }
         }, CancellationToken.None, TaskCreationOptions.DenyChildAttach,
             ScriptExecutionScheduler.Shared(_options)).Unwrap().PipeTo(self,
-            success: r => new ExpressionEvalResult(r));
+            success: r => new ExpressionEvalResult(r),
+            failure: ex => new ExpressionEvalFailed(ex));
     }
 
     /// <summary>
@@ -333,6 +338,18 @@ public class ScriptActor : ReceiveActor, IWithTimers
         if (_evalPending) { _evalPending = false; StartExpressionEvaluation(); }
     }
 
+    /// <summary>
+    /// Applies a faulted off-dispatcher evaluation task (N2): logs the fault via the
+    /// existing error path (which also increments the health counter), then reuses the
+    /// false-result path — clearing in-flight, applying the false edge, and draining any
+    /// pending evaluation — so a transient scheduler fault cannot permanently park the trigger.
+    /// </summary>
+    private void HandleExpressionEvalFailed(ExpressionEvalFailed msg)
+    {
+        LogExpressionError(msg.Cause);
+        HandleExpressionEvalResult(new ExpressionEvalResult(false));
+    }
+
     /// <summary>
     /// Applies a WhileTrue trigger's condition-state transition: on the
     /// false→true edge, fire once and start the re-fire timer; on the
@@ -621,6 +638,15 @@ public class ScriptActor : ReceiveActor, IWithTimers
     /// the actor thread.
     /// </summary>
     private sealed record ExpressionEvalResult(bool Result);
+
+    /// <summary>
+    /// Piped back to self when the off-dispatcher evaluation TASK itself faults
+    /// (e.g. ObjectDisposedException from a disposed ScriptExecutionScheduler
+    /// during shutdown) — the inner body's catch never sees that. Without this
+    /// mapping the actor receives an unhandled Status.Failure and _evalInFlight
+    /// stays true forever, permanently parking the expression trigger (N2).
+    /// </summary>
+    internal sealed record ExpressionEvalFailed(Exception Cause);
 }
 
 // ── Trigger config types ──