From 90f54414ab7da195b8ab5a32e31ca042b105ee97 Mon Sep 17 00:00:00 2001
From: Christian Byrne <cbyrne@comfy.org>
Date: Mon, 11 Aug 2025 13:12:31 -0700
Subject: [PATCH] fix: Multiple links from reroute create single slot on
 SubgraphOutputNode (#4915)

Co-authored-by: Claude <noreply@anthropic.com>
---
 src/lib/litegraph/src/canvas/LinkConnector.ts | 44 ++++++++++++++++++-
 1 file changed, 42 insertions(+), 2 deletions(-)

diff --git a/src/lib/litegraph/src/canvas/LinkConnector.ts b/src/lib/litegraph/src/canvas/LinkConnector.ts
index 8dea4c7a0e..ea57a3a6f9 100644
--- a/src/lib/litegraph/src/canvas/LinkConnector.ts
+++ b/src/lib/litegraph/src/canvas/LinkConnector.ts
@@ -17,6 +17,8 @@ import type {
   INodeInputSlot,
   INodeOutputSlot
 } from '@/lib/litegraph/src/interfaces'
+import { EmptySubgraphInput } from '@/lib/litegraph/src/subgraph/EmptySubgraphInput'
+import { EmptySubgraphOutput } from '@/lib/litegraph/src/subgraph/EmptySubgraphOutput'
 import { Subgraph } from '@/lib/litegraph/src/subgraph/Subgraph'
 import type { SubgraphInput } from '@/lib/litegraph/src/subgraph/SubgraphInput'
 import { SubgraphInputNode } from '@/lib/litegraph/src/subgraph/SubgraphInputNode'
@@ -640,8 +642,27 @@ export class LinkConnector {
       const output = ioNode.getSlotInPosition(canvasX, canvasY)
       if (!output) throw new Error('No output slot found for link.')
 
+      // Track the actual slot to use for all connections
+      let targetSlot = output
+
       for (const link of renderLinks) {
-        link.connectToSubgraphOutput(output, this.events)
+        link.connectToSubgraphOutput(targetSlot, this.events)
+
+        // If we just connected to an EmptySubgraphOutput, check if we should reuse the slot
+        if (output instanceof EmptySubgraphOutput && ioNode.slots.length > 0) {
+          // Get the last created slot (newest one)
+          const createdSlot = ioNode.slots[ioNode.slots.length - 1]
+
+          // Only reuse the slot if the next link's type would be compatible
+          // Otherwise, keep using EmptySubgraphOutput to create a new slot
+          const nextLink = renderLinks[renderLinks.indexOf(link) + 1]
+          if (nextLink && link.fromSlot.type === nextLink.fromSlot.type) {
+            targetSlot = createdSlot
+          } else {
+            // Reset to EmptySubgraphOutput for different types
+            targetSlot = output
+          }
+        }
       }
     } else if (
       connectingTo === 'output' &&
@@ -650,8 +671,27 @@ export class LinkConnector {
       const input = ioNode.getSlotInPosition(canvasX, canvasY)
       if (!input) throw new Error('No input slot found for link.')
 
+      // Same logic for SubgraphInputNode if needed
+      let targetSlot = input
+
       for (const link of renderLinks) {
-        link.connectToSubgraphInput(input, this.events)
+        link.connectToSubgraphInput(targetSlot, this.events)
+
+        // If we just connected to an EmptySubgraphInput, check if we should reuse the slot
+        if (input instanceof EmptySubgraphInput && ioNode.slots.length > 0) {
+          // Get the last created slot (newest one)
+          const createdSlot = ioNode.slots[ioNode.slots.length - 1]
+
+          // Only reuse the slot if the next link's type would be compatible
+          // Otherwise, keep using EmptySubgraphInput to create a new slot
+          const nextLink = renderLinks[renderLinks.indexOf(link) + 1]
+          if (nextLink && link.fromSlot.type === nextLink.fromSlot.type) {
+            targetSlot = createdSlot
+          } else {
+            // Reset to EmptySubgraphInput for different types
+            targetSlot = input
+          }
+        }
       }
     } else {
       console.error(