Hoist a batch input only where the compiler proves it cannot vary per lane

node-graph/libraries/core-types/src/record.rs

@@ -300,6 +300,10 @@ pub struct RecordLayout {
 	pub layout: Layout,
 	pub frame_bytes: usize,
 	pub plan: Vec<(usize, usize, usize)>,
+	/// Inputs whose value cannot change with the innermost index, as a bitmask
+	/// over input positions. Empty is the safe default: an uninstalled layout
+	/// rebinds every input per lane.
+	pub lane_invariant: u32,
 }
 
 /// its registry entry so the compiler can fold each wire's layout without
@@ -400,7 +404,12 @@ impl LayoutMeta {
 			}
 			_ => Vec::new(),
 		};
-		RecordLayout { layout, frame_bytes, plan }
+		RecordLayout {
+			layout,
+			frame_bytes,
+			plan,
+			lane_invariant: 0,
+		}
 	}
 }
 

node-graph/libraries/core-types/src/runtime.rs

@@ -273,6 +273,7 @@ mod tests {
 			frame_bytes: layout.frame_bytes(),
 			plan: Vec::new(),
 			layout: layout.clone(),
+			lane_invariant: u32::MAX,
 		});
 		RecordExtract::new(graph, &layout)
 	}