interrupt goes first

src/wf_core/runtime/ops/flow.py

@@ -74,6 +74,7 @@ def advance_frame(
     *,
     outcome: str,
     next_node_id: str,
+    front: bool = False,
 ) -> None:
     frame.prior_outcome = outcome
     frame.activated_incoming_edge = frame.node_id
@@ -84,7 +85,7 @@ def advance_frame(
         wake_parent_for_child_progress(run, frame.id)
     else:
         frame.finished_at_node_id = None
-        mark_frame_pending(run, frame.id)
+        mark_frame_pending(run, frame.id, front=front)
     run.sync_from_current_frame()
 
 

src/wf_core/runtime/step.py

@@ -53,6 +53,7 @@ def complete_step(
 ) -> RunState:
     """Record a completed step and advance the active frame."""
     next_node_id = index.next_node_id(node_id, outcome)
+    next_step = index.nodes_by_id.get(next_node_id)
 
     append_step_result_trace(
         run,
@@ -67,6 +68,7 @@ def complete_step(
         run.frames[frame_id],
         outcome=outcome,
         next_node_id=next_node_id,
+        front=isinstance(next_step, InterruptNode),
     )
     return run