Deep copy subgraphs to clipboard, update nested ids on paste (#5003)

* Deep copy to clipboard, update nested ids on paste

The copyToClipboard function wasn't walking subgraphs and leaving nested
subgraphs unserialized. This has now been fixed.

This requires that equivalent support be added to _pasteFromClipboard to
update the ids of nested subgraphs which are pasted.

* Add extra advisory comments

src/lib/litegraph/src/LGraphCanvas.ts

@@ -3608,6 +3608,7 @@ export class LGraphCanvas
       subgraphs: []
     }
 
+    // NOTE: logic for traversing nested subgraphs depends on this being a set.
     const subgraphs = new Set<Subgraph>()
 
     // Create serialisable objects
@@ -3646,8 +3647,13 @@ export class LGraphCanvas
     }
 
     // Add unique subgraph entries
-    // TODO: Must find all nested subgraphs
+    // NOTE: subgraphs is appended to mid iteration.
     for (const subgraph of subgraphs) {
+      for (const node of subgraph.nodes) {
+        if (node instanceof SubgraphNode) {
+          subgraphs.add(node.subgraph)
+        }
+      }
       const cloned = subgraph.clone(true).asSerialisable()
       serialisable.subgraphs.push(cloned)
     }
@@ -3764,12 +3770,19 @@ export class LGraphCanvas
       created.push(group)
     }
 
+    // Update subgraph ids with nesting
+    function updateSubgraphIds(nodes: { type: string }[]) {
+      for (const info of nodes) {
+        const subgraph = results.subgraphs.get(info.type)
+        if (!subgraph) continue
+        info.type = subgraph.id
+        updateSubgraphIds(subgraph.nodes)
+      }
+    }
+    updateSubgraphIds(parsed.nodes)
+
     // Nodes
     for (const info of parsed.nodes) {
-      // If the subgraph was cloned, update references to use the new subgraph ID.
-      const subgraph = results.subgraphs.get(info.type)
-      if (subgraph) info.type = subgraph.id
-
       const node = info.type == null ? null : LiteGraph.createNode(info.type)
       if (!node) {
         // failedNodes.push(info)