[backport cloud/1.33] fix: loader node widget value shows placeholder instead of filename on cloud (#7046)

Backport of #7005 to `cloud/1.33`

Automatically created by backport workflow.

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-7046-backport-cloud-1-33-fix-loader-node-widget-value-shows-placeholder-instead-of-filename-2bb6d73d365081bd9531c08bbaeb8634)
by [Unito](https://www.unito.io)

Co-authored-by: Christian Byrne <cbyrne@comfy.org>

cloud-loader-dropdown.md

@@ -0,0 +1,24 @@
+Fixes loader dropdown placeholder
+===============================
+
+Cloud loader dropdowns hydrate via `useAssetWidgetData(nodeType)`, so `dropdownItems` stays empty until the Asset API returns friendly filenames. Meanwhile `modelValue` already holds the saved asset and the watcher at [WidgetSelectDropdown.vue#L215-L227](https://github.com/Comfy-Org/ComfyUI_frontend/blob/main/src/renderer/extensions/vueNodes/widgets/components/WidgetSelectDropdown.vue#L215-L227) only tracks `modelValue`. It runs before assets load, fails to find a match, clears `selectedSet`, and the placeholder persists.
+
+```ts
+watch(
+  modelValue,
+  (currentValue) => {
+    if (currentValue === undefined) {
+      selectedSet.value.clear()
+      return
+    }
+    const item = dropdownItems.value.find((item) => item.name === currentValue)
+    if (item) {
+      selectedSet.value.clear()
+      selectedSet.value.add(item.id)
+    }
+  },
+  { immediate: true }
+)
+```
+
+Once the API resolves, `dropdownItems` recomputes but nothing resyncs because the watcher never sees that change. Desktop doesn’t hit this because it still reads from `widget.options.values` immediately.

src/renderer/extensions/vueNodes/widgets/components/WidgetSelectDropdown.vue

@@ -213,12 +213,13 @@ const acceptTypes = computed(() => {
 const layoutMode = ref<LayoutMode>(props.defaultLayoutMode ?? 'grid')
 
 watch(
-  modelValue,
-  (currentValue) => {
+  [modelValue, dropdownItems],
+  ([currentValue, _dropdownItems]) => {
     if (currentValue === undefined) {
       selectedSet.value.clear()
       return
     }
+
     const item = dropdownItems.value.find((item) => item.name === currentValue)
     if (item) {
       selectedSet.value.clear()