test: subgraph integration contracts and expanded Playwright coverage (#10123)

## Summary

Add integration contract tests (unit) and expanded Playwright coverage
for subgraph promotion, hydration, navigation, and lifecycle edge
behaviors.

## Changes

- **What**: 22 unit/integration tests across 9 files covering promotion
store sync, widget view lifecycle, input link resolution, pseudo-widget
cache, navigation viewport restore, and subgraph operations. 13
Playwright E2E tests covering proxyWidgets hydration stability, promoted
source removal cleanup, pseudo-preview unpack/remove, multi-link
representative round-trip, nested promotion retarget, and navigation
state on workflow switch.
- **Helpers**: Added `isPseudoPreviewEntry`, `getPseudoPreviewWidgets`,
`getNonPreviewPromotedWidgets` to promotedWidgets helper. Added
`SubgraphHelper.getNodeCount()`.

## Review Focus

- Test-only PR — no production code changes
- Validates existing subgraph behaviors are covered by regression tests
before further feature work
- Phase 4 (unit/integration contracts) and Phase 5 (Playwright
expansion) of the subgraph test coverage plan

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-10123-test-subgraph-integration-contracts-and-expanded-Playwright-coverage-3256d73d365081258023e3a763859e00)
by [Unito](https://www.unito.io)

---------

Co-authored-by: Amp <amp@ampcode.com>
Co-authored-by: GitHub Action <action@github.com>

src/components/rightSidePanel/parameters/WidgetActions.test.ts

@@ -7,7 +7,9 @@ import { beforeEach, describe, expect, it, vi } from 'vitest'
 import { createI18n } from 'vue-i18n'
 
 import type { LGraphNode } from '@/lib/litegraph/src/litegraph'
+import type { SubgraphNode } from '@/lib/litegraph/src/subgraph/SubgraphNode'
 import type { IBaseWidget } from '@/lib/litegraph/src/types/widgets'
+import { usePromotionStore } from '@/stores/promotionStore'
 
 import WidgetActions from './WidgetActions.vue'
 
@@ -93,8 +95,11 @@ describe('WidgetActions', () => {
   function createMockNode(): LGraphNode {
     return {
       id: 1,
-      type: 'TestNode'
-    } as LGraphNode
+      type: 'TestNode',
+      rootGraph: { id: 'graph-test' },
+      computeSize: vi.fn(),
+      size: [200, 100]
+    } as unknown as LGraphNode
   }
 
   function mountWidgetActions(widget: IBaseWidget, node: LGraphNode) {
@@ -206,4 +211,66 @@ describe('WidgetActions', () => {
 
     expect(wrapper.emitted('resetToDefault')![0]).toEqual(['option1'])
   })
+
+  it('demotes promoted widgets by immediate interior node identity when shown from parent context', async () => {
+    mockGetInputSpecForWidget.mockReturnValue({
+      type: 'CUSTOM'
+    })
+    const parentSubgraphNode = {
+      id: 4,
+      rootGraph: { id: 'graph-test' },
+      computeSize: vi.fn(),
+      size: [300, 150]
+    } as unknown as SubgraphNode
+    const node = {
+      id: 4,
+      type: 'SubgraphNode',
+      rootGraph: { id: 'graph-test' }
+    } as unknown as LGraphNode
+    const widget = {
+      name: 'text',
+      type: 'text',
+      value: 'value',
+      label: 'Text',
+      options: {},
+      y: 0,
+      sourceNodeId: '3',
+      sourceWidgetName: 'text',
+      disambiguatingSourceNodeId: '1'
+    } as IBaseWidget
+
+    const promotionStore = usePromotionStore()
+    promotionStore.promote('graph-test', 4, {
+      sourceNodeId: '3',
+      sourceWidgetName: 'text',
+      disambiguatingSourceNodeId: '1'
+    })
+
+    const wrapper = mount(WidgetActions, {
+      props: {
+        widget,
+        node,
+        label: 'Text',
+        parents: [parentSubgraphNode],
+        isShownOnParents: true
+      },
+      global: {
+        plugins: [i18n]
+      }
+    })
+
+    const hideButton = wrapper
+      .findAll('button')
+      .find((button) => button.text().includes('Hide input'))
+    expect(hideButton).toBeDefined()
+    await hideButton?.trigger('click')
+
+    expect(
+      promotionStore.isPromoted('graph-test', 4, {
+        sourceNodeId: '3',
+        sourceWidgetName: 'text',
+        disambiguatingSourceNodeId: '1'
+      })
+    ).toBe(false)
+  })
 })