Improve comments on #2389

cosmos/dbt/selector.py

@@ -191,6 +191,9 @@ def select_node_precursors(self, nodes: dict[str, DbtNode], root_id: str, select
                 new_generation: set[str] = set()
                 for node_id in previous_generation:
                     if node_id not in processed_nodes:
+                        # When using dbt-loom for cross-project references, external nodes are filtered out
+                        # during manifest loading but local nodes may still reference them in depends_on.
+                        # Skip missing nodes to gracefully stop traversal at project boundaries.
                         if node_id in nodes:
                             new_generation.update(set(nodes[node_id].depends_on))
                         processed_nodes.add(node_id)
@@ -588,6 +591,9 @@ def select_nodes_ids_by_intersection(self) -> set[str]:
         if self.config.graph_selectors:
             graph_selected_nodes = self.select_by_graph_operator()
             for node_id in graph_selected_nodes:
+                # When using dbt-loom for cross-project references, external nodes are filtered out
+                # during manifest loading but may be collected during graph traversal via depends_on.
+                # Skip these external node IDs that don't exist in the nodes dict.
                 if node_id not in self.nodes:
                     continue
                 node = self.nodes[node_id]