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src/lib/litegraph/src/canvas/MovingLinkBase.ts

@@ -11,6 +11,7 @@ import type {
 } from '@/lib/litegraph/src/interfaces'
 import type { SubgraphInput } from '@/lib/litegraph/src/subgraph/SubgraphInput'
 import type { SubgraphOutput } from '@/lib/litegraph/src/subgraph/SubgraphOutput'
+import type { NodeLike } from '@/lib/litegraph/src/types/NodeLike'
 import { LinkDirection } from '@/lib/litegraph/src/types/globalEnums'
 
 import type { RenderLink } from './RenderLink'
@@ -99,6 +100,14 @@ export abstract class MovingLinkBase implements RenderLink {
     this.inputPos = inputNode.getInputPos(inputIndex)
   }
 
+  abstract canConnectToInput(
+    inputNode: NodeLike,
+    input: INodeInputSlot
+  ): boolean
+  abstract canConnectToOutput(
+    outputNode: NodeLike,
+    output: INodeOutputSlot
+  ): boolean
   abstract connectToInput(
     node: LGraphNode,
     input: INodeInputSlot,

src/lib/litegraph/src/canvas/RenderLink.ts

@@ -11,6 +11,7 @@ import type {
 import type { SubgraphIONodeBase } from '@/lib/litegraph/src/subgraph/SubgraphIONodeBase'
 import type { SubgraphInput } from '@/lib/litegraph/src/subgraph/SubgraphInput'
 import type { SubgraphOutput } from '@/lib/litegraph/src/subgraph/SubgraphOutput'
+import type { NodeLike } from '@/lib/litegraph/src/types/NodeLike'
 import type { LinkDirection } from '@/lib/litegraph/src/types/globalEnums'
 
 export interface RenderLink {
@@ -38,6 +39,17 @@ export interface RenderLink {
   /** The reroute that the link is being connected from. */
   readonly fromReroute?: Reroute
 
+  /**
+   * Capability checks used for hit-testing and validation during drag.
+   * Implementations should return `false` when a connection is not possible
+   * rather than throwing.
+   */
+  canConnectToInput(node: NodeLike, input: INodeInputSlot): boolean
+  canConnectToOutput(node: NodeLike, output: INodeOutputSlot): boolean
+  /** Optional: only some links support validating subgraph IO or reroutes. */
+  canConnectToSubgraphInput?(input: SubgraphInput): boolean
+  canConnectToReroute?(reroute: Reroute): boolean
+
   connectToInput(
     node: LGraphNode,
     input: INodeInputSlot,

src/renderer/core/canvas/links/linkConnectorAdapter.ts

@@ -115,8 +115,8 @@ export class LinkConnectorAdapter {
     const node = this.network.getNodeById(nodeId)
     const output = node?.outputs?.[outputIndex]
     if (!node || !output) return false
-    return (this.linkConnector.renderLinks as any[]).some(
-      (link) => link?.canConnectToOutput?.(node, output) === true
+    return this.linkConnector.renderLinks.some((link) =>
+      link.canConnectToOutput(node, output)
     )
   }