[backport core/1.42] test: subgraph integration contracts and expanded Playwright coverage (#10327)

Backport of #10123, #9967, and #9972 to `core/1.42`

Includes three cherry-picks in dependency order:
1. #9972 — `fix: resolve all lint warnings` (clean)
2. #9967 — `test: harden subgraph test coverage and remove low-value
tests` (clean)
3. #10123 — `test: subgraph integration contracts and expanded
Playwright coverage` (1 conflict, auto-resolved by rerere from #10326)

See #10326 for core/1.41 backport with detailed conflict resolution
notes.

---------

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

src/components/rightSidePanel/parameters/WidgetActions.vue

@@ -5,10 +5,11 @@ import { useI18n } from 'vue-i18n'
 
 import MoreButton from '@/components/button/MoreButton.vue'
 import Button from '@/components/ui/button/Button.vue'
+import type { PromotedWidgetSource } from '@/core/graph/subgraph/promotedWidgetTypes'
 import { isPromotedWidgetView } from '@/core/graph/subgraph/promotedWidgetTypes'
-import { resolvePromotedWidgetSource } from '@/core/graph/subgraph/resolvePromotedWidgetSource'
 import {
   demoteWidget,
+  getSourceNodeId,
   promoteWidget
 } from '@/core/graph/subgraph/promotionUtils'
 import type { LGraphNode } from '@/lib/litegraph/src/litegraph'
@@ -16,6 +17,7 @@ import type { SubgraphNode } from '@/lib/litegraph/src/subgraph/SubgraphNode'
 import type { IBaseWidget } from '@/lib/litegraph/src/types/widgets'
 import { useCanvasStore } from '@/renderer/core/canvas/canvasStore'
 import { useNodeDefStore } from '@/stores/nodeDefStore'
+import { usePromotionStore } from '@/stores/promotionStore'
 import { useFavoritedWidgetsStore } from '@/stores/workspace/favoritedWidgetsStore'
 import { getWidgetDefaultValue, promptWidgetLabel } from '@/utils/widgetUtil'
 import type { WidgetValue } from '@/utils/widgetUtil'
@@ -41,6 +43,7 @@ const label = defineModel<string>('label', { required: true })
 const canvasStore = useCanvasStore()
 const favoritedWidgetsStore = useFavoritedWidgetsStore()
 const nodeDefStore = useNodeDefStore()
+const promotionStore = usePromotionStore()
 const { t } = useI18n()
 
 const hasParents = computed(() => parents?.length > 0)
@@ -73,26 +76,29 @@ function handleHideInput() {
   if (!parents?.length) return
 
   if (isPromotedWidgetView(widget)) {
-    const sourceWidget = resolvePromotedWidgetSource(node, widget)
-    if (!sourceWidget) {
-      console.error('Could not resolve source widget for promoted widget')
-      return
-    }
+    const disambiguatingSourceNodeId = getSourceNodeId(widget)
 
-    demoteWidget(sourceWidget.node, sourceWidget.widget, parents)
+    for (const parent of parents) {
+      const source: PromotedWidgetSource = {
+        sourceNodeId:
+          String(node.id) === String(parent.id)
+            ? widget.sourceNodeId
+            : String(node.id),
+        sourceWidgetName: widget.sourceWidgetName,
+        disambiguatingSourceNodeId
+      }
+      promotionStore.demote(parent.rootGraph.id, parent.id, source)
+      parent.computeSize(parent.size)
+    }
+    canvasStore.canvas?.setDirty(true, true)
   } else {
-    // For regular widgets (not yet promoted), use them directly
     demoteWidget(node, widget, parents)
   }
-
-  canvasStore.canvas?.setDirty(true, true)
 }
 
 function handleShowInput() {
   if (!parents?.length) return
-
   promoteWidget(node, widget, parents)
-  canvasStore.canvas?.setDirty(true, true)
 }
 
 function handleToggleFavorite() {