d

CLI.py

@@ -2118,13 +2118,23 @@ class PipelineExecutor:
         except Exception:
             effective_source = current_source
 
-        selection_only = bool(
-            len(stages) == 1 and stages[0] and stages[0][0].startswith("@")
+        selection_start = bool(
+            stages and stages[0] and stages[0][0].startswith("@")
         )
-        if pending_tail and selection_only:
+
+        def _tail_is_suffix(existing: List[List[str]], tail: List[List[str]]) -> bool:
+            if not tail or not existing:
+                return False
+            if len(tail) > len(existing):
+                return False
+            return existing[-len(tail):] == tail
+
+        if pending_tail and selection_start:
             if (pending_source is None) or (effective_source
                                             and pending_source == effective_source):
-                stages = list(stages) + list(pending_tail)
+                # Only append the pending tail if the user hasn't already provided it.
+                if not _tail_is_suffix(stages, pending_tail):
+                    stages = list(stages) + list(pending_tail)
                 try:
                     if hasattr(ctx, "clear_pending_pipeline_tail"):
                         ctx.clear_pending_pipeline_tail()