fix: keep referenced subgraph definitions on unpack

- prevent subgraph definition deletion while other nodes still reference the same subgraph type

- stop unpack from force-deleting definitions after removing the unpacked node

- add regression coverage for unpacking one instance while another remains

Amp-Thread-ID: https://ampcode.com/threads/T-019c9e10-f581-7091-b103-05ec41896bda
Co-authored-by: Amp <amp@ampcode.com>

src/lib/litegraph/src/LGraph.ts

@@ -1064,13 +1064,23 @@ export class LGraph
     }
 
     if (node.isSubgraphNode()) {
-      forEachNode(node.subgraph, (innerNode) => {
-        innerNode.onRemoved?.()
-        innerNode.graph?.onNodeRemoved?.(innerNode)
-        if (innerNode.isSubgraphNode())
-          this.rootGraph.subgraphs.delete(innerNode.subgraph.id)
-      })
-      this.rootGraph.subgraphs.delete(node.subgraph.id)
+      const allGraphs = [this.rootGraph, ...this.rootGraph.subgraphs.values()]
+      const hasRemainingReferences = allGraphs.some((graph) =>
+        graph.nodes.some(
+          (candidate) =>
+            candidate !== node &&
+            candidate.isSubgraphNode() &&
+            candidate.type === node.subgraph.id
+        )
+      )
+
+      if (!hasRemainingReferences) {
+        forEachNode(node.subgraph, (innerNode) => {
+          innerNode.onRemoved?.()
+          innerNode.graph?.onNodeRemoved?.(innerNode)
+        })
+        this.rootGraph.subgraphs.delete(node.subgraph.id)
+      }
     }
 
     // callback
@@ -1862,6 +1872,7 @@ export class LGraph
         })
       )
     )
+
     return { subgraph, node: subgraphNode as SubgraphNode }
   }
 
@@ -2043,9 +2054,19 @@ export class LGraph
       })
     }
     this.remove(subgraphNode)
-    this.subgraphs.delete(subgraphNode.subgraph.id)
+
+    // Deduplicate links by (oid, oslot, tid, tslot) to prevent repeated
+    // disconnect/reconnect cycles on widget inputs that can shift slot indices.
+    const seenLinks = new Set<string>()
+    const dedupedNewLinks = newLinks.filter((link) => {
+      const key = `${link.oid}:${link.oslot}:${link.tid}:${link.tslot}`
+      if (seenLinks.has(key)) return false
+      seenLinks.add(key)
+      return true
+    })
+
     const linkIdMap = new Map<LinkId, LinkId[]>()
-    for (const newLink of newLinks) {
+    for (const newLink of dedupedNewLinks) {
       let created: LLink | null | undefined
       if (newLink.oid == SUBGRAPH_INPUT_ID) {
         if (!(this instanceof Subgraph)) {
@@ -2319,7 +2340,6 @@ export class LGraph
       const usedSubgraphs = [...this._subgraphs.values()]
         .filter((subgraph) => usedSubgraphIds.has(subgraph.id))
         .map((x) => x.asSerialisable())
-
       if (usedSubgraphs.length > 0) {
         data.definitions = { subgraphs: usedSubgraphs }
       }