test: add failing tests for multi-instance subgraph widget value collision

Multiple SubgraphNode instances sharing the same blueprint overwrite
each other's promoted widget values because PromotedWidgetView writes
directly to shared inner node widgets.

src/lib/litegraph/src/subgraph/SubgraphNode.multiInstance.test.ts

@@ -0,0 +1,118 @@
+import { createTestingPinia } from '@pinia/testing'
+import { setActivePinia } from 'pinia'
+import { beforeEach, describe, expect, it } from 'vitest'
+
+import type { ISlotType } from '@/lib/litegraph/src/litegraph'
+import { BaseWidget, LGraphNode } from '@/lib/litegraph/src/litegraph'
+
+import {
+  createTestSubgraph,
+  createTestSubgraphNode,
+  resetSubgraphFixtureState
+} from './__fixtures__/subgraphHelpers'
+
+function createNodeWithWidget(
+  title: string,
+  widgetValue: unknown = 42,
+  slotType: ISlotType = 'number'
+) {
+  const node = new LGraphNode(title)
+  const input = node.addInput('value', slotType)
+  node.addOutput('out', slotType)
+
+  // @ts-expect-error Abstract class instantiation
+  const widget = new BaseWidget({
+    name: 'widget',
+    type: 'number',
+    value: widgetValue,
+    y: 0,
+    options: { min: 0, max: 100, step: 1 },
+    node
+  })
+  node.widgets = [widget]
+  input.widget = { name: widget.name }
+
+  return { node, widget, input }
+}
+
+beforeEach(() => {
+  setActivePinia(createTestingPinia({ stubActions: false }))
+  resetSubgraphFixtureState()
+})
+
+describe('SubgraphNode multi-instance widget isolation', () => {
+  it('preserves distinct promoted widget values across instances of the same blueprint', () => {
+    const subgraph = createTestSubgraph({
+      inputs: [{ name: 'value', type: 'number' }]
+    })
+
+    const { node } = createNodeWithWidget('TestNode', 10)
+    subgraph.add(node)
+    subgraph.inputNode.slots[0].connect(node.inputs[0], node)
+
+    // Create two instances of the same subgraph
+    const instance1 = createTestSubgraphNode(subgraph, { id: 101 })
+    const instance2 = createTestSubgraphNode(subgraph, { id: 102 })
+
+    // Both should have promoted widgets
+    expect(instance1.widgets).toHaveLength(1)
+    expect(instance2.widgets).toHaveLength(1)
+
+    // Set different values on each instance
+    instance1.widgets![0].value = 10
+    instance2.widgets![0].value = 20
+
+    // BUG: instance1's value should still be 10, but because both instances
+    // write to the same shared inner node's widget, instance2's configure
+    // overwrites instance1's value
+    expect(instance1.widgets![0].value).toBe(10)
+    expect(instance2.widgets![0].value).toBe(20)
+  })
+
+  it('preserves promoted widget values after configure with different widgets_values', () => {
+    const subgraph = createTestSubgraph({
+      inputs: [{ name: 'value', type: 'number' }]
+    })
+
+    const { node } = createNodeWithWidget('TestNode', 0)
+    subgraph.add(node)
+    subgraph.inputNode.slots[0].connect(node.inputs[0], node)
+
+    const instance1 = createTestSubgraphNode(subgraph, { id: 201 })
+    const instance2 = createTestSubgraphNode(subgraph, { id: 202 })
+
+    // Simulate what LGraph.configure does: call configure with different widgets_values
+    instance1.configure({
+      id: 201,
+      type: subgraph.id,
+      pos: [100, 100],
+      size: [200, 100],
+      inputs: [],
+      outputs: [],
+      mode: 0,
+      order: 0,
+      flags: {},
+      properties: { proxyWidgets: [['-1', 'widget']] },
+      widgets_values: [10]
+    })
+
+    instance2.configure({
+      id: 202,
+      type: subgraph.id,
+      pos: [400, 100],
+      size: [200, 100],
+      inputs: [],
+      outputs: [],
+      mode: 0,
+      order: 1,
+      flags: {},
+      properties: { proxyWidgets: [['-1', 'widget']] },
+      widgets_values: [20]
+    })
+
+    // BUG: After configuring both, instance1 should still be 10
+    // but instance2's configure overwrites the shared inner widget
+    expect(instance1.widgets?.[0]?.value).toBe(10)
+    expect(instance2.widgets?.[0]?.value).toBe(20)
+  })
+})