fix: restore legacy slot links

Amp-Thread-ID: https://ampcode.com/threads/T-01a02889-c911-708b-bf1a-11dfb0904fff

Author: ampagent

src/lib/litegraph/src/node/NodeInputSlot.ts

@@ -1,5 +1,5 @@
 import type { LGraphNode } from '@/lib/litegraph/src/LGraphNode'
-import type { LinkId } from '@/lib/litegraph/src/LLink'
+import type { LLink,LinkId } from '@/lib/litegraph/src/LLink'
 import { LabelPosition } from '@/lib/litegraph/src/draw'
 import type {
   INodeInputSlot,
@@ -9,7 +9,8 @@ import type {
 } from '@/lib/litegraph/src/interfaces'
 import { LiteGraph } from '@/lib/litegraph/src/litegraph'
 import { NodeSlot } from '@/lib/litegraph/src/node/NodeSlot'
-import { inputHasLink, inputLinkId } from '@/lib/litegraph/src/node/slotLinks'
+import { inputHasLink, inputLink } from '@/lib/litegraph/src/node/slotLinks'
+import { restoreLegacyLink } from '@/lib/litegraph/src/node/restoreLegacyLink'
 import { warnDeprecated } from '@/lib/litegraph/src/utils/feedback'
 import type { IDrawOptions } from '@/lib/litegraph/src/node/NodeSlot'
 import type { SubgraphInput } from '@/lib/litegraph/src/subgraph/SubgraphInput'
@@ -19,25 +20,35 @@ import type { IBaseWidget } from '@/lib/litegraph/src/types/widgets'
 
 export class NodeInputSlot extends NodeSlot implements INodeInputSlot {
   alwaysVisible?: boolean
+  private legacyLink?: LLink
 
   /**
    * @deprecated Reads return the store-derived link id. Assigning null
-   * disconnects through the store; assigning an id is ignored. First-party
-   * code uses the slotLinks helpers and node topology methods.
+   * disconnects through the store; assigning that id again restores the
+   * observed topology when it is still valid.
    */
   get link(): LinkId | null {
     warnDeprecated(
       'input.link is deprecated. Read connectivity via node.isInputConnected(slot) / node.getInputLink(slot); mutate via node.connect() / node.disconnectInput().'
     )
-    return linkIdOf(this)
+    const link = linkOf(this)
+    if (link) this.legacyLink = link
+    return link?.id ?? null
   }
 
   set link(value: LinkId | null) {
     warnDeprecated(
       'Assignment to input.link is deprecated; null disconnects through the link store. Mutate via node.connect() / node.disconnectInput().'
     )
     const slot = indexOf(this)
-    if (value === null && slot !== -1) this._node.disconnectInput(slot)
+    if (slot === -1) return
+    if (value === null) {
+      const link = linkOf(this)
+      if (link) this.legacyLink = link
+      this._node.disconnectInput(slot)
+    } else if (this.legacyLink?.id === value) {
+      restoreLegacyLink(this.legacyLink, this._node, slot, 'input')
+    }
   }
 
   get isWidgetInputSlot(): boolean {
@@ -124,7 +135,10 @@ function indexOf(slot: NodeInputSlot): number {
 }
 
 function linkIdOf(slot: NodeInputSlot): LinkId | null {
+  return linkOf(slot)?.id ?? null
+}
+
+function linkOf(slot: NodeInputSlot): LLink | undefined {
   const { graph } = slot.node
-  if (!graph) return null
-  return inputLinkId(graph, slot.node.id, indexOf(slot)) ?? null
+  return graph ? inputLink(graph, slot.node.id, indexOf(slot)) : undefined
 }

src/lib/litegraph/src/node/NodeOutputSlot.ts

@@ -1,5 +1,5 @@
 import type { LGraphNode } from '@/lib/litegraph/src/LGraphNode'
-import type { LinkId } from '@/lib/litegraph/src/LLink'
+import type { LLink,LinkId } from '@/lib/litegraph/src/LLink'
 import { LabelPosition } from '@/lib/litegraph/src/draw'
 import type {
   INodeInputSlot,
@@ -11,11 +11,8 @@ import { LiteGraph } from '@/lib/litegraph/src/litegraph'
 import { createArrayMutationView } from '@/lib/litegraph/src/infrastructure/createMutationView'
 import { NodeSlot } from '@/lib/litegraph/src/node/NodeSlot'
 import type { IDrawOptions } from '@/lib/litegraph/src/node/NodeSlot'
-import {
-  outputHasLinks,
-  outputLinkIds,
-  outputLinks
-} from '@/lib/litegraph/src/node/slotLinks'
+import { restoreLegacyLink } from '@/lib/litegraph/src/node/restoreLegacyLink'
+import { outputHasLinks, outputLinks } from '@/lib/litegraph/src/node/slotLinks'
 import type { SubgraphInput } from '@/lib/litegraph/src/subgraph/SubgraphInput'
 import type { SubgraphOutput } from '@/lib/litegraph/src/subgraph/SubgraphOutput'
 import { isSubgraphOutput } from '@/lib/litegraph/src/subgraph/subgraphUtils'
@@ -25,13 +22,14 @@ export class NodeOutputSlot extends NodeSlot implements INodeOutputSlot {
   _data?: unknown
   slot_index?: number
   private readonly legacyLinkIds!: LinkId[]
+  private readonly legacyLinks!: Map<LinkId, LLink>
   private readonly legacyLinksView!: LinkId[]
   private legacyLinksPresent!: boolean
 
   /**
    * @deprecated Reads return a stable store-derived view. Removing ids from the
-   * view disconnects them; additions are discarded. First-party code uses the
-   * slotLinks helpers and node topology methods.
+   * view disconnects them; adding a previously observed id restores its
+   * topology when it is still valid.
    */
   get links(): LinkId[] | null {
     warnDeprecated(
@@ -51,7 +49,9 @@ export class NodeOutputSlot extends NodeSlot implements INodeOutputSlot {
   }
 
   private synchronizeLegacyLinks(): void {
-    const ids = linkIdsOf(this)
+    const links = linksOf(this)
+    for (const link of links) this.legacyLinks.set(link.id, link)
+    const ids = links.map((link) => link.id)
     this.legacyLinkIds.splice(0, this.legacyLinkIds.length, ...ids)
     if (ids.length) this.legacyLinksPresent = true
   }
@@ -73,10 +73,17 @@ export class NodeOutputSlot extends NodeSlot implements INodeOutputSlot {
     }
 
     const desired = new Set(this.legacyLinkIds)
-    for (const link of outputLinks(graph, this._node.id, slot)) {
+    const current = outputLinks(graph, this._node.id, slot)
+    for (const link of current) this.legacyLinks.set(link.id, link)
+    for (const link of current) {
       if (desired.has(link.id)) continue
       graph.getNodeById(link.target_id)?.disconnectInput(link.target_slot)
     }
+    for (const id of desired) {
+      if (graph.getLink(id)) continue
+      const link = this.legacyLinks.get(id)
+      if (link) restoreLegacyLink(link, this._node, slot, 'output')
+    }
     this.synchronizeLegacyLinks()
   }
 
@@ -103,6 +110,7 @@ export class NodeOutputSlot extends NodeSlot implements INodeOutputSlot {
     const legacyLinkIds: LinkId[] = []
     Object.defineProperties(this, {
       legacyLinkIds: { value: legacyLinkIds },
+      legacyLinks: { value: new Map<LinkId, LLink>() },
       legacyLinksView: {
         value: createArrayMutationView(
           legacyLinkIds,
@@ -175,6 +183,10 @@ function indexOf(slot: NodeOutputSlot): number {
 }
 
 function linkIdsOf(slot: NodeOutputSlot): LinkId[] {
+  return linksOf(slot).map((link) => link.id)
+}
+
+function linksOf(slot: NodeOutputSlot): LLink[] {
   const { graph } = slot.node
-  return graph ? outputLinkIds(graph, slot.node.id, indexOf(slot)) : []
+  return graph ? outputLinks(graph, slot.node.id, indexOf(slot)) : []
 }

src/lib/litegraph/src/node/restoreLegacyLink.ts

@@ -0,0 +1,82 @@
+import type { LGraphNode } from '@/lib/litegraph/src/LGraphNode'
+import type { LLink } from '@/lib/litegraph/src/LLink'
+import { registerLinkTopology } from '@/lib/litegraph/src/LLink'
+import { inputHasLink } from '@/lib/litegraph/src/node/slotLinks'
+import { anchorRerouteChain } from '@/lib/litegraph/src/Reroute'
+import { LiteGraph } from '@/lib/litegraph/src/litegraph'
+import { NodeSlotType } from '@/lib/litegraph/src/types/globalEnums'
+
+export function restoreLegacyLink(
+  link: LLink,
+  node: LGraphNode,
+  slot: number,
+  side: 'input' | 'output'
+): boolean {
+  const { graph } = node
+  if (!graph || graph.getLink(link.id)) return false
+  if (
+    side === 'input'
+      ? !link.hasTarget(node.id, slot)
+      : !link.hasOrigin(node.id, slot)
+  )
+    return false
+
+  const outputNode = graph.getNodeById(link.origin_id)
+  const inputNode = graph.getNodeById(link.target_id)
+  const output = outputNode?.outputs[link.origin_slot]
+  const input = inputNode?.inputs[link.target_slot]
+  if (!outputNode || !inputNode || !output || !input) return false
+  if (inputHasLink(graph, inputNode.id, link.target_slot)) return false
+  if (!LiteGraph.isValidConnection(output.type, input.type)) return false
+  if (
+    inputNode.onConnectInput?.(
+      link.target_slot,
+      output.type,
+      output,
+      outputNode,
+      link.origin_slot
+    ) === false ||
+    outputNode.onConnectOutput?.(
+      link.origin_slot,
+      input.type,
+      input,
+      inputNode,
+      link.target_slot
+    ) === false
+  )
+    return false
+
+  if (link.parentId !== undefined && !graph.reroutes.has(link.parentId)) {
+    link.parentId = undefined
+  }
+  if (!registerLinkTopology(graph, link)) return false
+
+  anchorRerouteChain(graph, link)
+  graph.incrementVersion()
+  outputNode.onConnectionsChange?.(
+    NodeSlotType.OUTPUT,
+    link.origin_slot,
+    true,
+    link,
+    output
+  )
+  if (graph.getLink(link.id) !== link) {
+    graph.afterChange()
+    return false
+  }
+  inputNode.onConnectionsChange?.(
+    NodeSlotType.INPUT,
+    link.target_slot,
+    true,
+    link,
+    input
+  )
+  if (graph.getLink(link.id) !== link) {
+    graph.afterChange()
+    return false
+  }
+
+  outputNode.setDirtyCanvas(false, true)
+  graph.afterChange()
+  return true
+}