diff --git a/kiln-core/src/script.rs b/kiln-core/src/script.rs
index 5ff7b96..bc18dea 100644
--- a/kiln-core/src/script.rs
+++ b/kiln-core/src/script.rs
@@ -327,21 +327,30 @@ impl ScriptHost {
 
     /// Promotes ready actions from object `i`'s output queue onto the board queue.
     ///
-    /// While the object's ready timer is running, nothing is pulled. Otherwise the
-    /// leading run of zero-cost actions is promoted, followed by at most one timed
-    /// action (which arms the timer and ends the pump). The board-queue guard keeps a
-    /// second pump in the same tick from double-promoting.
+    /// While the object's ready timer is running, nothing is pulled. While a timed
+    /// action for this object is already in the board queue, nothing is pulled (a
+    /// second timed action would race it). Otherwise the leading run of zero-cost
+    /// actions is promoted, followed by at most one timed action (which arms the timer
+    /// and ends the pump). All queued free actions therefore land in the board queue
+    /// in the same pump call as the next timed action — they apply atomically in the
+    /// same `resolve()`.
     fn pump(&mut self, i: usize) {
         let oid = self.objects[i].object_id;
-        // Don't re-promote if this object already has actions awaiting resolution.
-        if self.board_queue.borrow().iter().any(|ba| ba.source == oid) {
+
+        // A running cooldown blocks all further pulls (timed or not).
+        if self.objects[i].ready_timer > 0.0 {
             return;
         }
+
+        // Don't promote while a timed action for this object is already in the board
+        // queue and awaiting resolution — a second timed action would race it.
+        if self.board_queue.borrow().iter()
+            .any(|ba| ba.source == oid && ba.action.time_cost() > 0.0)
+        {
+            return;
+        }
+
         loop {
-            // A running cooldown blocks all further pulls (timed or not).
-            if self.objects[i].ready_timer > 0.0 {
-                break;
-            }
             let queue = self.objects[i].output_queue.clone();
             let cost = match queue.borrow().front() {
                 Some(action) => action.time_cost(),