App mode - discard slow preview messages to prevent overwriting output image (#9261)

## Summary

Prevent latent previews received after the job/node has already finished
processing overwriting the actual output display

## Changes

- **What**: 
- updates job preview store to also track which node the preview was for
- updates linear progress tracking to store executed nodes enabling
skipping previews of these

## Review Focus

<!-- Critical design decisions or edge cases that need attention -->

<!-- If this PR fixes an issue, uncomment and update the line below -->
<!-- Fixes #ISSUE_NUMBER -->

## Screenshots (if applicable)

<!-- Add screenshots or video recording to help explain your changes -->

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-9261-App-mode-discard-slow-preview-messages-to-prevent-overwriting-output-image-3136d73d3650817884c2ce2ff5993b9e)
by [Unito](https://www.unito.io)

src/stores/jobPreviewStore.test.ts

@@ -0,0 +1,102 @@
+import { createPinia, setActivePinia } from 'pinia'
+import { beforeEach, describe, expect, it, vi } from 'vitest'
+import { ref } from 'vue'
+
+import { useJobPreviewStore } from '@/stores/jobPreviewStore'
+import { releaseSharedObjectUrl } from '@/utils/objectUrlUtil'
+
+const previewMethodRef = ref('latent2rgb')
+
+vi.mock('@/platform/settings/settingStore', () => ({
+  useSettingStore: () => ({
+    get: (key: string) => {
+      if (key === 'Comfy.Execution.PreviewMethod') return previewMethodRef.value
+      return undefined
+    }
+  })
+}))
+
+vi.mock('@/utils/objectUrlUtil', () => ({
+  retainSharedObjectUrl: vi.fn(),
+  releaseSharedObjectUrl: vi.fn()
+}))
+
+describe('jobPreviewStore', () => {
+  beforeEach(() => {
+    vi.clearAllMocks()
+    setActivePinia(createPinia())
+    previewMethodRef.value = 'latent2rgb'
+  })
+
+  it('stores preview with nodeId', () => {
+    const store = useJobPreviewStore()
+    store.setPreviewUrl('prompt-1', 'blob:url-1', 'node-5')
+
+    expect(store.nodePreviewsByPromptId['prompt-1']).toEqual({
+      url: 'blob:url-1',
+      nodeId: 'node-5'
+    })
+  })
+
+  it('stores preview without nodeId', () => {
+    const store = useJobPreviewStore()
+    store.setPreviewUrl('prompt-1', 'blob:url-1')
+
+    expect(store.nodePreviewsByPromptId['prompt-1']).toEqual({
+      url: 'blob:url-1',
+      nodeId: undefined
+    })
+  })
+
+  it('derives previewsByPromptId as url-only map', () => {
+    const store = useJobPreviewStore()
+    store.setPreviewUrl('p1', 'blob:a', 'node-1')
+    store.setPreviewUrl('p2', 'blob:b', 'node-2')
+
+    expect(store.previewsByPromptId).toEqual({
+      p1: 'blob:a',
+      p2: 'blob:b'
+    })
+  })
+
+  it('clears a single preview', () => {
+    const store = useJobPreviewStore()
+    store.setPreviewUrl('p1', 'blob:a', 'node-1')
+    store.setPreviewUrl('p2', 'blob:b', 'node-2')
+
+    store.clearPreview('p1')
+
+    expect(store.nodePreviewsByPromptId['p1']).toBeUndefined()
+    expect(store.nodePreviewsByPromptId['p2']).toBeDefined()
+    expect(store.previewsByPromptId).toEqual({ p2: 'blob:b' })
+  })
+
+  it('clears all previews', () => {
+    const store = useJobPreviewStore()
+    store.setPreviewUrl('p1', 'blob:a', 'node-1')
+    store.setPreviewUrl('p2', 'blob:b', 'node-2')
+
+    store.clearAllPreviews()
+
+    expect(store.nodePreviewsByPromptId).toEqual({})
+    expect(store.previewsByPromptId).toEqual({})
+  })
+
+  it('skips duplicate url', () => {
+    const store = useJobPreviewStore()
+    store.setPreviewUrl('p1', 'blob:a', 'node-1')
+
+    store.setPreviewUrl('p1', 'blob:a', 'node-1')
+
+    expect(releaseSharedObjectUrl).not.toHaveBeenCalled()
+  })
+
+  it('ignores setPreviewUrl when previews are disabled', () => {
+    previewMethodRef.value = 'none'
+    const store = useJobPreviewStore()
+
+    store.setPreviewUrl('p1', 'blob:a', 'node-1')
+
+    expect(store.nodePreviewsByPromptId).toEqual({})
+  })
+})

src/stores/jobPreviewStore.ts

@@ -8,44 +8,59 @@ import {
 } from '@/utils/objectUrlUtil'
 
 type PromptPreviewMap = Record<string, string>
+interface NodePromptPreview {
+  url: string
+  nodeId?: string
+}
 
 export const useJobPreviewStore = defineStore('jobPreview', () => {
   const settingStore = useSettingStore()
-  const previewsByPromptId = ref<PromptPreviewMap>({})
-  const readonlyPreviewsByPromptId = readonly(previewsByPromptId)
+  const nodePreviewsByPromptId = ref<Record<string, NodePromptPreview>>({})
 
   const previewMethod = computed(() =>
     settingStore.get('Comfy.Execution.PreviewMethod')
   )
   const isPreviewEnabled = computed(() => previewMethod.value !== 'none')
 
-  function setPreviewUrl(promptId: string | undefined, url: string) {
+  const previewsByPromptId = computed(() => {
+    const result: PromptPreviewMap = {}
+    for (const [k, v] of Object.entries(nodePreviewsByPromptId.value)) {
+      result[k] = v.url
+    }
+    return result
+  })
+
+  function setPreviewUrl(
+    promptId: string | undefined,
+    url: string,
+    nodeId?: string
+  ) {
     if (!promptId || !isPreviewEnabled.value) return
-    const current = previewsByPromptId.value[promptId]
-    if (current === url) return
-    if (current) releaseSharedObjectUrl(current)
+    const current = nodePreviewsByPromptId.value[promptId]
+    if (current?.url === url) return
+    if (current) releaseSharedObjectUrl(current.url)
     retainSharedObjectUrl(url)
-    previewsByPromptId.value = {
-      ...previewsByPromptId.value,
-      [promptId]: url
+    nodePreviewsByPromptId.value = {
+      ...nodePreviewsByPromptId.value,
+      [promptId]: { url, nodeId }
     }
   }
 
   function clearPreview(promptId: string | undefined) {
     if (!promptId) return
-    const current = previewsByPromptId.value[promptId]
+    const current = nodePreviewsByPromptId.value[promptId]
     if (!current) return
-    releaseSharedObjectUrl(current)
-    const next = { ...previewsByPromptId.value }
+    releaseSharedObjectUrl(current.url)
+    const next = { ...nodePreviewsByPromptId.value }
     delete next[promptId]
-    previewsByPromptId.value = next
+    nodePreviewsByPromptId.value = next
   }
 
   function clearAllPreviews() {
-    Object.values(previewsByPromptId.value).forEach((url) => {
+    for (const { url } of Object.values(nodePreviewsByPromptId.value)) {
       releaseSharedObjectUrl(url)
-    })
-    previewsByPromptId.value = {}
+    }
+    nodePreviewsByPromptId.value = {}
   }
 
   watch(isPreviewEnabled, (enabled) => {
@@ -53,7 +68,8 @@ export const useJobPreviewStore = defineStore('jobPreview', () => {
   })
 
   return {
-    previewsByPromptId: readonlyPreviewsByPromptId,
+    nodePreviewsByPromptId: readonly(nodePreviewsByPromptId),
+    previewsByPromptId,
     isPreviewEnabled,
     setPreviewUrl,
     clearPreview,