fix(next): force inactive live preview after passing conditions (#14048)

Follow-up to #14012.

Once live preview conditions have passed, it is jarring for the live
preview window to suddenly appear. It should be that, despite
preferences, if the live preview window did not _load_ active, then it
should not become active until the user explicitly toggles it on.

This is especially poor UX while creating a new doc. If the conditional
URL is based on a field that has't been filled yet, upon filling that
field (with autosave), live preview suddenly appears and the entire page
shifts mid-edit.

Before:


https://github.com/user-attachments/assets/0da75306-eed3-4a77-bc58-d8a8dd0254bf

After:


https://github.com/user-attachments/assets/c7918601-959d-4ac5-b168-066afc3d879d

---
- To see the specific tasks where the Asana app for GitHub is being
used, see below:
  - https://app.asana.com/0/0/1211534009142634

test/live-preview/collections/ConditionalURL.ts

@@ -1,7 +1,7 @@
 import type { CollectionConfig } from 'payload'
 
-export const NoURLCollection: CollectionConfig = {
-  slug: 'no-url',
+export const ConditionalURL: CollectionConfig = {
+  slug: 'conditional-url',
   admin: {
     livePreview: {
       url: ({ data }) => (data?.enabled ? '/live-preview/static' : null),

test/live-preview/collections/StaticURL.ts

@@ -4,7 +4,7 @@ export const StaticURLCollection: CollectionConfig = {
   slug: 'static-url',
   admin: {
     livePreview: {
-      url: '/live-preview/hello-world',
+      url: '/live-preview/static',
     },
   },
   fields: [

test/live-preview/config.ts

@@ -6,9 +6,9 @@ import { buildConfigWithDefaults } from '../buildConfigWithDefaults.js'
 import { MediaBlock } from './blocks/MediaBlock/index.js'
 import { Categories } from './collections/Categories.js'
 import { CollectionLevelConfig } from './collections/CollectionLevelConfig.js'
+import { ConditionalURL } from './collections/ConditionalURL.js'
 import { CustomLivePreview } from './collections/CustomLivePreview.js'
 import { Media } from './collections/Media.js'
-import { NoURLCollection } from './collections/NoURL.js'
 import { Pages } from './collections/Pages.js'
 import { Posts } from './collections/Posts.js'
 import { SSR } from './collections/SSR.js'
@@ -68,7 +68,7 @@ export default buildConfigWithDefaults({
     CollectionLevelConfig,
     StaticURLCollection,
     CustomLivePreview,
-    NoURLCollection,
+    ConditionalURL,
   ],
   globals: [Header, Footer],
   onInit: seed,

test/live-preview/e2e.spec.ts

@@ -179,22 +179,47 @@ describe('Live Preview', () => {
     await expect.poll(async () => iframe.getAttribute('src')).toMatch(/\/live-preview/)
   })
 
-  test('collection — does not render iframe when live preview url is falsy', async () => {
-    const noURL = new AdminUrlUtil(serverURL, 'no-url')
+  test('collection — does not render live preview when url is null', async () => {
+    const noURL = new AdminUrlUtil(serverURL, 'conditional-url')
     await page.goto(noURL.create)
     await page.locator('#field-title').fill('No URL')
     await saveDocAndAssert(page)
+
+    // No toggler should render
     const toggler = page.locator('button#live-preview-toggler')
     await expect(toggler).toBeHidden()
     await expect(page.locator('iframe.live-preview-iframe')).toBeHidden()
 
+    // Check the `enabled` field
     const enabledCheckbox = page.locator('#field-enabled')
     await enabledCheckbox.check()
     await saveDocAndAssert(page)
 
+    // Toggler is present but not iframe
     await expect(toggler).toBeVisible()
-    await toggleLivePreview(page)
-    await expect(page.locator('iframe.live-preview-iframe')).toBeVisible()
+    await expect(page.locator('iframe.live-preview-iframe')).toBeHidden()
+
+    // Toggle the iframe back on, which will save to prefs
+    // We need to explicitly test for this, as we don't want live preview to suddenly appear
+    await toggleLivePreview(page, {
+      targetState: 'on',
+    })
+
+    // Uncheck the `enabled` field
+    await enabledCheckbox.uncheck()
+    await saveDocAndAssert(page)
+
+    // Toggler and iframe are gone
+    await expect(toggler).toBeHidden()
+    await expect(page.locator('iframe.live-preview-iframe')).toBeHidden()
+
+    // Check the `enabled` field
+    await enabledCheckbox.check()
+    await saveDocAndAssert(page)
+
+    // Toggler is present but still not iframe
+    await expect(toggler).toBeVisible()
+    await expect(page.locator('iframe.live-preview-iframe')).toBeHidden()
   })
 
   test('collection — retains static URL across edits', async () => {
@@ -204,12 +229,12 @@ describe('Live Preview', () => {
     await toggleLivePreview(page, { targetState: 'on' })
 
     const iframe = page.locator('iframe.live-preview-iframe')
-    await expect.poll(async () => iframe.getAttribute('src')).toMatch(/\/live-preview\/hello/)
+    await expect.poll(async () => iframe.getAttribute('src')).toMatch(/\/live-preview\/static/)
 
     const titleField = page.locator('#field-title')
     await titleField.fill('New Title')
     await saveDocAndAssert(page)
-    await expect.poll(async () => iframe.getAttribute('src')).toMatch(/\/live-preview\/hello/)
+    await expect.poll(async () => iframe.getAttribute('src')).toMatch(/\/live-preview\/static/)
   })
 
   test('collection csr — iframe reflects form state on change', async () => {