Migrate parentIds when converting to subgraph (#5708)

The parentId property on links and reroutes was not handled at all in
the "Convert to Subgraph" code.
This needs to be addressed in 4 cases
- A new external input link must have parentId set to the first
non-migrated reroute
- A new external output link must have the parentId of it's eldest
remaining child set to undefined
- A new internal input link must have the parentId of it's eldest
remaining child set to undefined
- A new internal output link must have the parentId set to the first
migrated reroute

This is handled in two parts by adding logic where the boundry links is
created
- The change involves mutation of inputs (which isn't great) but the
function here was already mutating inputs into an invalid state
  - @DrJKL Do you see a quick way to better fix both these cases?

Looks like litegraph tests aren't enabled and cursory glance shows
multiple need to be updated to reflect recent changes. I'll still try to
add some tests anyways.
EDIT: Tests are non functional. Seems the subgraph conversion call
requires the rest of the frontend is running and has event listeners to
register the subgraph node def. More work than anticipated, best
revisited later

Resolves #5669

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-5708-Migrate-parentIds-when-converting-to-subgraph-2746d73d365081f78acff4454092c74a)
by [Unito](https://www.unito.io)

---------

Co-authored-by: Alexander Brown <drjkl@comfy.org>

src/lib/litegraph/src/LGraph.ts

@@ -1571,8 +1571,21 @@ export class LGraph
 
     // Inputs, outputs, and links
     const links = internalLinks.map((x) => x.asSerialisable())
-    const inputs = mapSubgraphInputsAndLinks(resolvedInputLinks, links)
-    const outputs = mapSubgraphOutputsAndLinks(resolvedOutputLinks, links)
+
+    const internalReroutes = new Map([...reroutes].map((r) => [r.id, r]))
+    const externalReroutes = new Map(
+      [...this.reroutes].filter(([id]) => !internalReroutes.has(id))
+    )
+    const inputs = mapSubgraphInputsAndLinks(
+      resolvedInputLinks,
+      links,
+      internalReroutes
+    )
+    const outputs = mapSubgraphOutputsAndLinks(
+      resolvedOutputLinks,
+      links,
+      externalReroutes
+    )
 
     // Prepare subgraph data
     const data = {
@@ -1714,10 +1727,10 @@ export class LGraph
     // Reconnect output links in parent graph
     i = 0
     for (const [, connections] of outputsGroupedByOutput.entries()) {
-      // Special handling: Subgraph output node
       i++
       for (const connection of connections) {
         const { input, inputNode, link, subgraphOutput } = connection
+        // Special handling: Subgraph output node
         if (link.target_id === SUBGRAPH_OUTPUT_ID) {
           link.origin_id = subgraphNode.id
           link.origin_slot = i - 1
@@ -2013,33 +2026,50 @@ export class LGraph
         while (parentId) {
           instance.parentId = parentId
           instance = this.reroutes.get(parentId)
-          if (!instance) throw new Error('Broken Id link when unpacking')
+          if (!instance) {
+            console.error('Broken Id link when unpacking')
+            break
+          }
           if (instance.linkIds.has(linkInstance.id))
             throw new Error('Infinite parentId loop')
           instance.linkIds.add(linkInstance.id)
           parentId = instance.parentId
         }
       }
+      if (!instance) continue
       parentId = newLink.iparent
       while (parentId) {
         const migratedId = rerouteIdMap.get(parentId)
-        if (!migratedId) throw new Error('Broken Id link when unpacking')
+        if (!migratedId) {
+          console.error('Broken Id link when unpacking')
+          break
+        }
         instance.parentId = migratedId
         instance = this.reroutes.get(migratedId)
-        if (!instance) throw new Error('Broken Id link when unpacking')
+        if (!instance) {
+          console.error('Broken Id link when unpacking')
+          break
+        }
         if (instance.linkIds.has(linkInstance.id))
           throw new Error('Infinite parentId loop')
         instance.linkIds.add(linkInstance.id)
         const oldReroute = subgraphNode.subgraph.reroutes.get(parentId)
-        if (!oldReroute) throw new Error('Broken Id link when unpacking')
+        if (!oldReroute) {
+          console.error('Broken Id link when unpacking')
+          break
+        }
         parentId = oldReroute.parentId
       }
+      if (!instance) break
       if (!newLink.externalFirst) {
         parentId = newLink.eparent
         while (parentId) {
           instance.parentId = parentId
           instance = this.reroutes.get(parentId)
-          if (!instance) throw new Error('Broken Id link when unpacking')
+          if (!instance) {
+            console.error('Broken Id link when unpacking')
+            break
+          }
           if (instance.linkIds.has(linkInstance.id))
             throw new Error('Infinite parentId loop')
           instance.linkIds.add(linkInstance.id)

src/lib/litegraph/src/subgraph/subgraphUtils.ts

@@ -4,6 +4,7 @@ import { LGraphNode } from '@/lib/litegraph/src/LGraphNode'
 import { LLink } from '@/lib/litegraph/src/LLink'
 import type { ResolvedConnection } from '@/lib/litegraph/src/LLink'
 import { Reroute } from '@/lib/litegraph/src/Reroute'
+import type { RerouteId } from '@/lib/litegraph/src/Reroute'
 import {
   SUBGRAPH_INPUT_ID,
   SUBGRAPH_OUTPUT_ID
@@ -259,10 +260,29 @@ export function groupResolvedByOutput(
 
   return groupedByOutput
 }
+function mapReroutes(
+  link: SerialisableLLink,
+  reroutes: Map<RerouteId, Reroute>
+) {
+  let child: SerialisableLLink | Reroute = link
+  let nextReroute =
+    child.parentId === undefined ? undefined : reroutes.get(child.parentId)
+
+  while (child.parentId !== undefined && nextReroute) {
+    child = nextReroute
+    nextReroute =
+      child.parentId === undefined ? undefined : reroutes.get(child.parentId)
+  }
+
+  const lastId = child.parentId
+  child.parentId = undefined
+  return lastId
+}
 
 export function mapSubgraphInputsAndLinks(
   resolvedInputLinks: ResolvedConnection[],
-  links: SerialisableLLink[]
+  links: SerialisableLLink[],
+  reroutes: Map<RerouteId, Reroute>
 ): SubgraphIO[] {
   // Group matching links
   const groupedByOutput = groupResolvedByOutput(resolvedInputLinks)
@@ -279,8 +299,10 @@ export function mapSubgraphInputsAndLinks(
       if (!input) continue
 
       const linkData = link.asSerialisable()
+      link.parentId = mapReroutes(link, reroutes)
       linkData.origin_id = SUBGRAPH_INPUT_ID
       linkData.origin_slot = inputs.length
+
       links.push(linkData)
       inputLinks.push(linkData)
     }
@@ -340,7 +362,8 @@ export function mapSubgraphInputsAndLinks(
  */
 export function mapSubgraphOutputsAndLinks(
   resolvedOutputLinks: ResolvedConnection[],
-  links: SerialisableLLink[]
+  links: SerialisableLLink[],
+  reroutes: Map<RerouteId, Reroute>
 ): SubgraphIO[] {
   // Group matching links
   const groupedByOutput = groupResolvedByOutput(resolvedOutputLinks)
@@ -355,10 +378,11 @@ export function mapSubgraphOutputsAndLinks(
       const { link, output } = resolved
       if (!output) continue
 
-      // Link
       const linkData = link.asSerialisable()
+      linkData.parentId = mapReroutes(link, reroutes)
       linkData.target_id = SUBGRAPH_OUTPUT_ID
       linkData.target_slot = outputs.length
+
       links.push(linkData)
       outputLinks.push(linkData)
     }