[TS] Add placeholder interfaces for subgraph classes (#851)

src/subgraphInterfaces.ts

@@ -0,0 +1,44 @@
+import type { LGraphNode } from "./LGraphNode"
+import type {
+  ExportedSubgraph,
+  ExportedSubgraphInstance,
+  ExposedWidget,
+  SubgraphIO,
+} from "./types/serialisation"
+import type { UUID } from "./utils/uuid"
+
+import { LGraph } from "@/LGraph"
+
+/** A subgraph definition. */
+export interface Subgraph extends LGraph {
+  parent: LGraph | Subgraph
+
+  /** The display name of the subgraph. */
+  name: string
+  /** Ordered list of inputs to the subgraph itself. Similar to a reroute, with the input side in the graph, and the output side in the subgraph. */
+  inputs: SubgraphIO[]
+  /** Ordered list of outputs from the subgraph itself. Similar to a reroute, with the input side in the subgraph, and the output side in the graph. */
+  outputs: SubgraphIO[]
+  /** A list of node widgets displayed in the parent graph, on the subgraph object. */
+  widgets: ExposedWidget[]
+
+  export(): ExportedSubgraph
+}
+
+/**
+ * An instance of a {@link Subgraph}, displayed as a node on the containing (parent) graph.
+ * @remarks
+ */
+export interface SubgraphInstance extends LGraphNode {
+  /** The definition of this subgraph; how its nodes are configured, etc. */
+  subgraphType: Subgraph
+
+  /** The root-level containing graph */
+  rootGraph: LGraph
+  /** The (sub)graph that contains this subgraph instance. */
+  parent: LGraph | Subgraph
+
+  type: UUID
+
+  export(): ExportedSubgraphInstance
+}