Replace raw node input indices with compile-time parameter symbols (#4387)

* Remove the dead InputAccessor traits and the uncallable test helper built on them

* Replace raw node input indices with macro-generated parameter symbols across the editor

* Audit dynamic input index usage, converting to parameter symbols and named input position constants

* Abstract the remaining input index plumbing behind ParameterRef APIs and accessors

* Build SetInputValue messages as struct literals to keep message enums impl-free

* Delete the typed parameter markers in favor of explicit-output test introspection

* Wire the interpolation control path input per chain node type

* Return no input when a parameter symbol is read against the wrong node's parameter view

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

@@ -141,24 +141,29 @@ impl<'i, I, O: 'i> Node<'i, I> for Pin<&'i (dyn NodeIO<'i, I, Output = O> + 'i)>
 	}
 }
 
-pub trait InputAccessorSource<'a, T>: InputAccessorSourceIdentifier + std::fmt::Debug {
-	fn get_input(&'a self, index: usize) -> Option<&'a T>;
-	fn set_input(&'a mut self, index: usize, value: T);
-}
-
-pub trait InputAccessorSourceIdentifier {
-	fn has_identifier(&self, identifier: &str) -> bool;
-}
-
-pub trait InputAccessor<'n, Source: 'n>
-where
-	Self: Sized,
-{
-	fn new_with_source(source: &'n Source) -> Option<Self>;
-}
-
-pub trait NodeInputDecleration {
+/// A compile-time symbol naming one parameter of one proto node.
+/// The node macro generates a unit struct implementing this for every parameter, so code can pass the type itself (e.g. `stroke::WeightInput`) instead of a raw input index.
+pub trait NodeParameter {
+	/// The proto node this parameter belongs to.
+	const NODE_IDENTIFIER: ProtoNodeIdentifier;
+	/// Position of this parameter among the node's inputs.
+	/// Prefer passing the symbol to an API that accepts it; reach for this only at genuinely index-based boundaries.
 	const INDEX: usize;
-	fn identifier() -> ProtoNodeIdentifier;
-	type Result;
+}
+
+/// A runtime reference to one parameter of one proto node, for heterogeneous tables and runtime-chosen parameters.
+/// Convert a symbol with `.into()`; unlike a raw index, the node identifier and index always stay paired.
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct ParameterRef {
+	pub node_identifier: ProtoNodeIdentifier,
+	pub input_index: usize,
+}
+
+impl<P: NodeParameter> From<P> for ParameterRef {
+	fn from(_: P) -> Self {
+		ParameterRef {
+			node_identifier: P::NODE_IDENTIFIER,
+			input_index: P::INDEX,
+		}
+	}
 }