Derive extent forwarding for level-preserving passthroughs

node-graph/node-macro/src/codegen.rs

@@ -1441,6 +1441,14 @@ pub(crate) fn generate_node_impl(crate_ident: &CrateIdent, parsed: &ParsedNodeFn
 				#core_types::node::Node::extent_at(&self.#name, __input, __level + #folded_levels)
 			}
 		}
+	} else if let Some(subject_index) = ir::forwarded_subject(&node).filter(|_| node.output.shape.depth == 0) {
+		// A level-preserving passthrough forwards its subject's extents.
+		let name = &regular_fields[subject_index].pat_ident.ident;
+		quote! {
+			fn extent_at(&self, __input: &#ctx_ident, __level: u8) -> #core_types::gpoll::GPoll<#core_types::gpoll::Extent> {
+				#core_types::node::Node::extent_at(&self.#name, __input, __level)
+			}
+		}
 	} else if node.output.shape.depth > 0 {
 		// A leveled output without an extent fn reports a lower bound;
 		// consumers size it by draining to the past-end signal.