fix(next): login redirect crashes page (#13786)

## Problem

When logging in with a `?redirect=`, the target page may crash. This
happens because the update from `SyncClientConfig` is applied in a
`useEffect`, which runs **_after_** the target page's client components
render. As a result, those components read the unauthenticated client
config on first render - even though they expect the authenticated one.

## Steps To Reproduce

1. logout
2. login with ?redirect=
3. document client component incorrectly still receives unauthenticated
client config on render
4. THEN the SyncClientConfig useEffect runs. Too late
5. Potential error (depending on the page, e.g. document view) -
document client component expects sth to be there, but it is not

## Solution

This PR replaces `SyncClientConfig` with a `RootPageConfigProvider`.
This new provider shadows the root layout’s `ConfigProvider` and ensures
the correct client config is available **_immediately_**.

It still updates the config using `useEffect` (the same
way`SyncClientConfig` did), but with one key difference:

- During the brief window between the redirect and the effect running,
it overrides the root layout’s config and provides the fresh,
authenticated config from the root page via the `RootConfigContext`.

This guarantees that client components on the target page receive the
correct config on first render, preventing errors caused by reading the
outdated unauthenticated config.

## Additional change - get rid of `UnsanitizedClientConfig` and
`sanitizeClientConfig`

Those functions added unnecessary complexity, just to build the
blocksMap. I removed those and perform the building of the `blocksMap`
server-side - directly in `createClientConfig`.

---
- To see the specific tasks where the Asana app for GitHub is being
used, see below:
  - https://app.asana.com/0/0/1211334752795621

Author: AlessioGr

packages/next/src/views/Root/SyncClientConfig.tsx

@@ -10,6 +10,7 @@ import type {
   SanitizedGlobalConfig,
 } from 'payload'
 
+import { RootPageConfigProvider } from '@payloadcms/ui'
 import { RenderServerComponent } from '@payloadcms/ui/elements/RenderServerComponent'
 import { getClientConfig } from '@payloadcms/ui/utilities/getClientConfig'
 import { notFound, redirect } from 'next/navigation.js'
@@ -27,7 +28,6 @@ import { isCustomAdminView } from '../../utilities/isCustomAdminView.js'
 import { isPublicAdminRoute } from '../../utilities/isPublicAdminRoute.js'
 import { getCustomViewByRoute } from './getCustomViewByRoute.js'
 import { getRouteData } from './getRouteData.js'
-import { SyncClientConfig } from './SyncClientConfig.js'
 
 export type GenerateViewMetadata = (args: {
   config: SanitizedConfig
@@ -300,8 +300,7 @@ export const RootPage = async ({
   })
 
   return (
-    <React.Fragment>
-      <SyncClientConfig clientConfig={clientConfig} />
+    <RootPageConfigProvider config={clientConfig}>
       {!templateType && <React.Fragment>{RenderedView}</React.Fragment>}
       {templateType === 'minimal' && (
         <MinimalTemplate className={templateClassName}>{RenderedView}</MinimalTemplate>
@@ -332,6 +331,6 @@ export const RootPage = async ({
           {RenderedView}
         </DefaultTemplate>
       )}
-    </React.Fragment>
+    </RootPageConfigProvider>
   )
 }

packages/next/src/views/Root/index.tsx

@@ -12,7 +12,6 @@ import type {
 
 import {
   type ClientCollectionConfig,
-  createClientCollectionConfig,
   createClientCollectionConfigs,
 } from '../collections/config/client.js'
 import { createClientBlocks } from '../fields/config/client.js'
@@ -43,16 +42,6 @@ export type ServerOnlyRootProperties = keyof Pick<
 
 export type ServerOnlyRootAdminProperties = keyof Pick<SanitizedConfig['admin'], 'components'>
 
-export type UnsanitizedClientConfig = {
-  admin: {
-    livePreview?: Omit<RootLivePreviewConfig, ServerOnlyLivePreviewProperties>
-  } & Omit<SanitizedConfig['admin'], 'components' | 'dependencies' | 'livePreview'>
-  blocks: ClientBlock[]
-  collections: ClientCollectionConfig[]
-  custom?: Record<string, any>
-  globals: ClientGlobalConfig[]
-} & Omit<SanitizedConfig, 'admin' | 'collections' | 'globals' | 'i18n' | ServerOnlyRootProperties>
-
 export type ClientConfig = {
   admin: {
     livePreview?: Omit<RootLivePreviewConfig, ServerOnlyLivePreviewProperties>
@@ -62,6 +51,7 @@ export type ClientConfig = {
   collections: ClientCollectionConfig[]
   custom?: Record<string, any>
   globals: ClientGlobalConfig[]
+  unauthenticated?: boolean
 } & Omit<SanitizedConfig, 'admin' | 'collections' | 'globals' | 'i18n' | ServerOnlyRootProperties>
 
 export type UnauthenticatedClientConfig = {
@@ -73,6 +63,7 @@ export type UnauthenticatedClientConfig = {
   globals: []
   routes: ClientConfig['routes']
   serverURL: ClientConfig['serverURL']
+  unauthenticated: ClientConfig['unauthenticated']
 }
 
 export const serverOnlyAdminConfigProperties: readonly Partial<ServerOnlyRootAdminProperties>[] = []
@@ -132,6 +123,7 @@ export const createUnauthenticatedClientConfig = ({
     globals: [],
     routes: clientConfig.routes,
     serverURL: clientConfig.serverURL,
+    unauthenticated: true,
   }
 }
 
@@ -189,6 +181,17 @@ export const createClientConfig = ({
           importMap,
         }).filter((block) => typeof block !== 'string') as ClientBlock[]
 
+        clientConfig.blocksMap = {}
+        if (clientConfig.blocks?.length) {
+          for (const block of clientConfig.blocks) {
+            if (!block?.slug) {
+              continue
+            }
+
+            clientConfig.blocksMap[block.slug] = block as ClientBlock
+          }
+        }
+
         break
       }
 

packages/payload/src/config/client.ts

@@ -1274,7 +1274,6 @@ export {
   serverOnlyAdminConfigProperties,
   serverOnlyConfigProperties,
   type UnauthenticatedClientConfig,
-  type UnsanitizedClientConfig,
 } from './config/client.js'
 export { defaults } from './config/defaults.js'
 

packages/payload/src/index.ts

@@ -303,7 +303,7 @@ export {
   RouteTransitionProvider,
   useRouteTransition,
 } from '../../providers/RouteTransition/index.js'
-export { ConfigProvider, useConfig } from '../../providers/Config/index.js'
+export { ConfigProvider, RootPageConfigProvider, useConfig } from '../../providers/Config/index.js'
 export { DocumentEventsProvider, useDocumentEvents } from '../../providers/DocumentEvents/index.js'
 export { DocumentInfoProvider, useDocumentInfo } from '../../providers/DocumentInfo/index.js'
 export { useDocumentTitle } from '../../providers/DocumentTitle/index.js'

packages/ui/src/exports/client/index.ts

@@ -6,7 +6,6 @@ import type {
   ClientGlobalConfig,
   CollectionSlug,
   GlobalSlug,
-  UnsanitizedClientConfig,
 } from 'payload'
 
 import React, { createContext, use, useCallback, useEffect, useMemo, useRef, useState } from 'react'
@@ -40,36 +39,14 @@ export type ClientConfigContext = {
 
 const RootConfigContext = createContext<ClientConfigContext | undefined>(undefined)
 
-function sanitizeClientConfig(
-  unSanitizedConfig: ClientConfig | UnsanitizedClientConfig,
-): ClientConfig {
-  if (!unSanitizedConfig?.blocks?.length || (unSanitizedConfig as ClientConfig).blocksMap) {
-    ;(unSanitizedConfig as ClientConfig).blocksMap = {}
-    return unSanitizedConfig as ClientConfig
-  }
-  const sanitizedConfig: ClientConfig = { ...unSanitizedConfig } as ClientConfig
-
-  sanitizedConfig.blocksMap = {}
-
-  for (const block of unSanitizedConfig.blocks) {
-    sanitizedConfig.blocksMap[block.slug] = block
-  }
-
-  return sanitizedConfig
-}
-
 export const ConfigProvider: React.FC<{
   readonly children: React.ReactNode
-  readonly config: ClientConfig | UnsanitizedClientConfig
+  readonly config: ClientConfig
 }> = ({ children, config: configFromProps }) => {
-  const [config, setConfigFn] = useState<ClientConfig>(() => sanitizeClientConfig(configFromProps))
+  const [config, setConfig] = useState<ClientConfig>(configFromProps)
 
   const isFirstRenderRef = useRef(true)
 
-  const setConfig = useCallback((newConfig: ClientConfig | UnsanitizedClientConfig) => {
-    setConfigFn(sanitizeClientConfig(newConfig))
-  }, [])
-
   // Need to update local config state if config from props changes, for HMR.
   // That way, config changes will be updated in the UI immediately without needing a refresh.
   useEffect(() => {
@@ -112,9 +89,52 @@ export const ConfigProvider: React.FC<{
     [collectionsBySlug, globalsBySlug],
   )
 
-  const value = useMemo(() => ({ config, getEntityConfig, setConfig }), [config, getEntityConfig])
+  const value = useMemo(
+    () => ({ config, getEntityConfig, setConfig }),
+    [config, getEntityConfig, setConfig],
+  )
 
   return <RootConfigContext value={value}>{children}</RootConfigContext>
 }
 
 export const useConfig = (): ClientConfigContext => use(RootConfigContext)
+
+/**
+ * This provider shadows the ConfigProvider on the _page_ level, allowing us to
+ * update the config when needed, e.g. after authentication.
+ * The layout ConfigProvider is not updated on page navigation / authentication,
+ * as the layout does not re-render in those cases.
+ *
+ * If the config here has the same reference as the config from the layout, we
+ * simply reuse the context from the layout to avoid unnecessary re-renders.
+ */
+export const RootPageConfigProvider: React.FC<{
+  readonly children: React.ReactNode
+  readonly config: ClientConfig
+}> = ({ children, config: configFromProps }) => {
+  const rootLayoutConfig = useConfig()
+  const { config, getEntityConfig, setConfig } = rootLayoutConfig
+
+  /**
+   * This useEffect is required in order for the _page_ to be able to refresh the client config,
+   * which may have been cached on the _layout_ level, where the ConfigProvider is managed.
+   * Since the layout does not re-render on page navigation / authentication, we need to manually
+   * update the config, as the user may have been authenticated in the process, which affects the client config.
+   */
+  useEffect(() => {
+    setConfig(configFromProps)
+  }, [configFromProps, setConfig])
+
+  if (config !== configFromProps && config.unauthenticated !== configFromProps.unauthenticated) {
+    // Between the unauthenticated config becoming authenticated (or the other way around) and the useEffect
+    // running, the config will be stale. In order to avoid having the wrong config in the context in that
+    // brief moment, we shadow the context here on the _page_ level and provide the updated config immediately.
+    return (
+      <RootConfigContext value={{ config: configFromProps, getEntityConfig, setConfig }}>
+        {children}
+      </RootConfigContext>
+    )
+  }
+
+  return <RootConfigContext value={rootLayoutConfig}>{children}</RootConfigContext>
+}

packages/ui/src/providers/Config/index.tsx

@@ -52,6 +52,7 @@ describe('Auth', () => {
     page = await context.newPage()
     initPageConsoleErrorCatch(page)
   })
+
   describe('create first user', () => {
     beforeAll(async () => {
       await reInitializeDB({
@@ -386,6 +387,36 @@ describe('Auth', () => {
 
         await saveDocAndAssert(page)
       })
+
+      test('ensure login page with redirect to users document redirects properly after login, without client error', async () => {
+        await page.goto(url.admin)
+
+        await page.goto(`${serverURL}/admin/logout`)
+
+        await expect(page.locator('.login')).toBeVisible()
+
+        const users = await payload.find({
+          collection: slug,
+          limit: 1,
+        })
+        const userDocumentRoute = `${serverURL}/admin/collections/users/${users?.docs?.[0]?.id}`
+
+        await page.goto(userDocumentRoute)
+
+        await expect(page.locator('#field-email')).toBeVisible()
+        await expect(page.locator('#field-password')).toBeVisible()
+
+        await page.locator('.form-submit > button').click()
+
+        // Expect to be redirected to the correct page
+        await expect
+          .poll(() => page.url(), { timeout: POLL_TOPASS_TIMEOUT })
+          .toBe(userDocumentRoute)
+
+        // Previously, this would crash the page with a "Cannot read properties of undefined (reading 'match')" error
+
+        await expect(page.locator('#field-roles')).toBeVisible()
+      })
     })
   })
 })