fix: keep Preview as Text rendering when the output payload has no text

browser_tests/tests/previewAsText.spec.ts

@@ -55,7 +55,10 @@ test.describe('Preview as Text node', () => {
       await comfyPage.menu.topbar.newWorkflowButton.click()
       await comfyPage.searchBoxV2.addNode('Preview as Text')
       const node = await comfyPage.vueNodes.getFixtureByTitle('Preview as Text')
-      const preview = node.root.locator('textarea')
+      const preview = comfyPage.vueNodes.getWidgetByName(
+        'Preview as Text',
+        'preview_text'
+      )
 
       await test.step('node previews execution result', async () => {
         const id = await comfyPage.vueNodes.getNodeIdByTitle('Preview as Text')
@@ -75,4 +78,59 @@ test.describe('Preview as Text node', () => {
       )
     }
   )
+
+  wstest(
+    'renders the payloads users reported blank',
+    { tag: '@vue-nodes' },
+    async ({ comfyPage, getWebSocket }) => {
+      const execution = new ExecutionHelper(comfyPage, await getWebSocket())
+
+      await comfyPage.menu.topbar.newWorkflowButton.click()
+      await comfyPage.searchBoxV2.addNode('Preview as Text')
+      const preview = comfyPage.vueNodes.getWidgetByName(
+        'Preview as Text',
+        'preview_text'
+      )
+      const id = await comfyPage.vueNodes.getNodeIdByTitle('Preview as Text')
+      const jobId = ''
+
+      const payloads = [
+        ['compact JSON from an LLM node', '{"name":"Comfy","emoji":"🌟"}'],
+        ['JSON array', '[{"a": 1}, {"b": 2}]'],
+        ['markdown-fenced JSON', '```json\n{"name":"Comfy"}\n```'],
+        ['non-ASCII text', '你好，世界。'],
+        ['prompt with a trailing space', '"A red car" is a great prompt. ']
+      ] as const
+
+      for (const [label, text] of payloads) {
+        await test.step(label, async () => {
+          execution.executed(jobId, id, { text: [text] })
+          await expect(preview).toHaveValue(text)
+        })
+      }
+
+      await test.step('numeric output from Get Video Components', async () => {
+        execution.executed(jobId, id, { text: 23.976 })
+        await expect(preview).toHaveValue('23.976')
+      })
+
+      await test.step('null text does not wedge the widget', async () => {
+        // The shape the Cloud backend produced when it misclassified the text
+        // as a filename and dropped it from the payload (BE-3601).
+        execution.executed(jobId, id, { text: [null] })
+        await expect(preview).toHaveValue('')
+
+        execution.executed(jobId, id, { text: ['recovered'] })
+        await expect(preview).toHaveValue('recovered')
+      })
+
+      await test.step('output with no text key does not wedge the widget', async () => {
+        execution.executed(jobId, id, {})
+        await expect(preview).toHaveValue('')
+
+        execution.executed(jobId, id, { text: ['recovered again'] })
+        await expect(preview).toHaveValue('recovered again')
+      })
+    }
+  )
 })

src/extensions/core/textPreviewWidgets.test.ts

@@ -1,6 +1,7 @@
 import { beforeEach, describe, expect, it, vi } from 'vitest'
 
 import type { LGraphNode } from '@/lib/litegraph/src/LGraphNode'
+import type { NodeExecutionOutput } from '@/schemas/apiSchema'
 
 interface MockWidget {
   name: string
@@ -100,4 +101,42 @@ describe('updateTextPreviewWidgets', () => {
     updateTextPreviewWidgets(node, { text: 'hello' })
     expect(node.widgets[0].value).toBe('hello')
   })
+
+  it.for([
+    ['null message', null],
+    ['undefined message', undefined],
+    ['message without text', {}],
+    ['null text', { text: null }],
+    ['empty array', { text: [] }],
+    ['array of only nulls', { text: [null, null] }]
+  ] as [string, NodeExecutionOutput | null | undefined][])(
+    'renders empty and does not throw for $0',
+    ([_label, message]) => {
+      expect(() => updateTextPreviewWidgets(node, message)).not.toThrow()
+      expect(node.widgets[0].value).toBe('')
+    }
+  )
+
+  it('drops null entries instead of rendering blank separators', () => {
+    updateTextPreviewWidgets(node, {
+      text: ['first', null, 'second']
+    } as unknown as NodeExecutionOutput)
+
+    expect(node.widgets[0].value).toBe('first\n\nsecond')
+  })
+
+  it('renders non-string entries rather than blanking the node', () => {
+    updateTextPreviewWidgets(node, {
+      text: ['first', 23.976, null, 'second']
+    } as unknown as NodeExecutionOutput)
+
+    expect(node.widgets[0].value).toBe('first\n\n23.976\n\nsecond')
+  })
+
+  it('stringifies a bare non-string scalar payload', () => {
+    updateTextPreviewWidgets(node, {
+      text: 23.976
+    } as unknown as NodeExecutionOutput)
+    expect(node.widgets[0].value).toBe('23.976')
+  })
 })

src/extensions/core/textPreviewWidgets.ts

@@ -1,6 +1,7 @@
 import type { LGraphNode } from '@/lib/litegraph/src/LGraphNode'
 import { resolveNodeRootGraphId } from '@/lib/litegraph/src/litegraph'
 import WidgetTextPreview from '@/renderer/extensions/vueNodes/widgets/components/WidgetTextPreview.vue'
+import type { NodeExecutionOutput } from '@/schemas/apiSchema'
 import type { CustomInputSpec } from '@/schemas/nodeDef/nodeDefSchemaV2'
 import { app } from '@/scripts/app'
 import { ComponentWidgetImpl, addWidget } from '@/scripts/domWidget'
@@ -66,13 +67,19 @@ export function addTextPreviewWidgets(node: LGraphNode) {
   modeWidget.serialize = false
 }
 
+function toPreviewText(text: unknown): string {
+  if (text == null) return ''
+  if (Array.isArray(text))
+    return text.filter((part) => part != null).join('\n\n')
+  return String(text)
+}
+
 export function updateTextPreviewWidgets(
   node: LGraphNode,
-  message: { text?: string | string[] }
+  message: NodeExecutionOutput | null | undefined
 ) {
   const preview = node.widgets?.find((w) => w.name === PREVIEW_WIDGET_NAME)
   if (!preview) return
 
-  const text = message.text ?? ''
-  preview.value = Array.isArray(text) ? text.join('\n\n') : text
+  preview.value = toPreviewText(message?.text)
 }