Update readme for eprh

Fixed two small issues with the config panel in the compiler playground:
1. Object descriptions were being confined in the config box and most of
it would not be visible upon hover
2. Changed it so that "Applied Configs" would only display a valid set
of configs, rather than switching between "Invalid Configs" and the set
of options. This would be less visually jarring for users as the Output
panel already displays errors. Additionally, if users want to see the
list of config options but have a currently broken config, they would
previously not know how to fix it.

Object hover before: 
<img width="702" height="481" alt="Screenshot 2025-09-26 at 10 41 03 AM"
src="https://github.com/user-attachments/assets/b2ddec2f-16ba-41a1-be1f-96211f46764c"
/>
Hover after:
<img width="702" height="481" alt="Screenshot 2025-09-26 at 10 40 37 AM"
src="https://github.com/user-attachments/assets/dc713a22-4710-46a8-a5d7-485060cc9074"
/>

Applied Configs always displays the last valid set of configs:


https://github.com/user-attachments/assets/2fb9232f-7388-4488-9b7a-bb48bf09e4ca

.eslintrc.js

@@ -517,6 +517,14 @@ module.exports = {
         __IS_INTERNAL_VERSION__: 'readonly',
       },
     },
+    {
+      files: ['packages/react-devtools-*/**/*.js'],
+      excludedFiles: '**/__tests__/**/*.js',
+      plugins: ['eslint-plugin-react-hooks-published'],
+      rules: {
+        'react-hooks-published/rules-of-hooks': ERROR,
+      },
+    },
     {
       files: ['packages/eslint-plugin-react-hooks/src/**/*'],
       extends: ['plugin:@typescript-eslint/recommended'],

CHANGELOG.md

@@ -1,3 +1,76 @@
+## 19.2.0 (October 1st, 2025)
+
+Below is a list of all new features, APIs, and bug fixes.
+
+Read the [React 19.2 release post](https://react.dev/blog/2025/10/01/react-19-2) for more information.
+
+### New React Features
+
+- [`<Activity>`](https://react.dev/reference/react/Activity): A new API to hide and restore the UI and internal state of its children.
+- [`useEffectEvent`](https://react.dev/reference/react/useEffectEvent) is a React Hook that lets you extract non-reactive logic into an [Effect Event](https://react.dev/learn/separating-events-from-effects#declaring-an-effect-event).
+- [`cacheSignal`](https://react.dev/reference/react/cacheSignal) (for RSCs) lets your know when the `cache()` lifetime is over.
+- [React Performance tracks](https://react.dev/reference/developer-tooling/react-performance-tracks) appear on the Performance panel’s timeline in your browser developer tools
+
+### New React DOM Features
+
+- Added resume APIs for partial pre-rendering with Web Streams:
+  - [`resume`](https://react.dev/reference/react-dom/server/resume): to resume a prerender to a stream.
+  - [`resumeAndPrerender`](https://react.dev/reference/react-dom/static/resumeAndPrerender): to resume a prerender to HTML.
+- Added resume APIs for partial pre-rendering with Node Streams:
+  - [`resumeToPipeableStream`](https://react.dev/reference/react-dom/server/resumeToPipeableStream): to resume a prerender to a stream.
+  - [`resumeAndPrerenderToNodeStream`](https://react.dev/reference/react-dom/static/resumeAndPrerenderToNodeStream): to resume a prerender to HTML.
+- Updated [`prerender`](https://react.dev/reference/react-dom/static/prerender) APIs to return a `postponed` state that can be passed to the `resume` APIs.
+
+### Notable changes
+
+- React DOM now batches suspense boundary reveals, matching the behavior of client side rendering. This change is especially noticeable when animating the reveal of Suspense boundaries e.g. with the upcoming `<ViewTransition>` Component. React will batch as much reveals as possible before the first paint while trying to hit popular first-contentful paint metrics.
+- Add Node Web Streams (`prerender`, `renderToReadableStream`) to server-side-rendering APIs for Node.js
+- Use underscore instead of `:` IDs generated by useId
+
+### All Changes
+
+#### React
+
+- `<Activity />` was developed over many years, starting before `ClassComponent.setState` (@acdlite @sebmarkbage and many others)
+- Stringify context as "SomeContext" instead of "SomeContext.Provider" (@kassens [#33507](https://github.com/facebook/react/pull/33507))
+- Include stack of cause of React instrumentation errors with `%o` placeholder (@eps1lon [#34198](https://github.com/facebook/react/pull/34198))
+- Fix infinite `useDeferredValue` loop in popstate event (@acdlite [#32821](https://github.com/facebook/react/pull/32821))
+- Fix a bug when an initial value was passed to `useDeferredValue` (@acdlite [#34376](https://github.com/facebook/react/pull/34376))
+- Fix a crash when submitting forms with Client Actions (@sebmarkbage [#33055](https://github.com/facebook/react/pull/33055))
+- Hide/unhide the content of dehydrated suspense boundaries if they resuspend (@sebmarkbage [#32900](https://github.com/facebook/react/pull/32900))
+- Avoid stack overflow on wide trees during Hot Reload (@sophiebits [#34145](https://github.com/facebook/react/pull/34145))
+- Improve Owner and Component stacks in various places (@sebmarkbage, @eps1lon: [#33629](https://github.com/facebook/react/pull/33629), [#33724](https://github.com/facebook/react/pull/33724), [#32735](https://github.com/facebook/react/pull/32735), [#33723](https://github.com/facebook/react/pull/33723))
+- Add `cacheSignal` (@sebmarkbage [#33557](https://github.com/facebook/react/pull/33557))
+
+#### React DOM
+
+- Block on Suspensey Fonts during reveal of server-side-rendered content (@sebmarkbage [#33342](https://github.com/facebook/react/pull/33342))
+- Use underscore instead of `:` for IDs generated by `useId` (@sebmarkbage, @eps1lon: [#32001](https://github.com/facebook/react/pull/32001), [https://github.com/facebook/react/pull/33342](https://github.com/facebook/react/pull/33342)[#33099](https://github.com/facebook/react/pull/33099), [#33422](https://github.com/facebook/react/pull/33422))
+- Stop warning when ARIA 1.3 attributes are used (@Abdul-Omira [#34264](https://github.com/facebook/react/pull/34264))
+- Allow `nonce` to be used on hoistable styles (@Andarist [#32461](https://github.com/facebook/react/pull/32461))
+- Warn for using a React owned node as a Container if it also has text content (@sebmarkbage [#32774](https://github.com/facebook/react/pull/32774))
+- s/HTML/text for for error messages if text hydration mismatches (@rickhanlonii [#32763](https://github.com/facebook/react/pull/32763))
+- Fix a bug with `React.use` inside `React.lazy`\-ed Component (@hi-ogawa [#33941](https://github.com/facebook/react/pull/33941))
+- Enable the `progressiveChunkSize` option for server-side-rendering APIs (@sebmarkbage [#33027](https://github.com/facebook/react/pull/33027))
+- Fix a bug with deeply nested Suspense inside Suspense fallback when server-side-rendering (@gnoff [#33467](https://github.com/facebook/react/pull/33467))
+- Avoid hanging when suspending after aborting while rendering (@gnoff [#34192](https://github.com/facebook/react/pull/34192))
+- Add Node Web Streams to server-side-rendering APIs for Node.js (@sebmarkbage [#33475](https://github.com/facebook/react/pull/33475))
+
+#### React Server Components
+
+- Preload `<img>` and `<link>` using hints before they're rendered (@sebmarkbage [#34604](https://github.com/facebook/react/pull/34604))
+- Log error if production elements are rendered during development (@eps1lon [#34189](https://github.com/facebook/react/pull/34189))
+- Fix a bug when returning a Temporary reference (e.g. a Client Reference) from Server Functions (@sebmarkbage [#34084](https://github.com/facebook/react/pull/34084), @denk0403 [#33761](https://github.com/facebook/react/pull/33761))
+- Pass line/column to `filterStackFrame` (@eps1lon [#33707](https://github.com/facebook/react/pull/33707))
+- Support Async Modules in Turbopack Server References (@lubieowoce [#34531](https://github.com/facebook/react/pull/34531))
+- Add support for .mjs file extension in Webpack (@jennyscript [#33028](https://github.com/facebook/react/pull/33028))
+- Fix a wrong missing key warning (@unstubbable [#34350](https://github.com/facebook/react/pull/34350))
+- Make console log resolve in predictable order (@sebmarkbage [#33665](https://github.com/facebook/react/pull/33665))
+
+#### React Reconciler
+
+- [createContainer](https://github.com/facebook/react/blob/v19.2.0/packages/react-reconciler/src/ReactFiberReconciler.js#L255-L261) and [createHydrationContainer](https://github.com/facebook/react/blob/v19.2.0/packages/react-reconciler/src/ReactFiberReconciler.js#L305-L312) had their parameter order adjusted after `on*` handlers to account for upcoming experimental APIs
+
 ## 19.1.1 (July 28, 2025)
 
 ### React

ReactVersions.js

@@ -7,18 +7,18 @@
 //
 // The @latest channel uses the version as-is, e.g.:
 //
-//   19.1.0
+//   19.3.0
 //
 // The @canary channel appends additional information, with the scheme
 // <version>-<label>-<commit_sha>, e.g.:
 //
-//   19.1.0-canary-a1c2d3e4
+//   19.3.0-canary-a1c2d3e4
 //
 // The @experimental channel doesn't include a version, only a date and a sha, e.g.:
 //
 //   0.0.0-experimental-241c4467e-20200129
 
-const ReactVersion = '19.2.0';
+const ReactVersion = '19.3.0';
 
 // The label used by the @canary channel. Represents the upcoming release's
 // stability. Most of the time, this will be "canary", but we may temporarily
@@ -33,8 +33,8 @@ const canaryChannelLabel = 'canary';
 const rcNumber = 0;
 
 const stablePackages = {
-  'eslint-plugin-react-hooks': '6.1.0',
-  'jest-react': '0.17.0',
+  'eslint-plugin-react-hooks': '6.2.0',
+  'jest-react': '0.18.0',
   react: ReactVersion,
   'react-art': ReactVersion,
   'react-dom': ReactVersion,
@@ -42,12 +42,12 @@ const stablePackages = {
   'react-server-dom-turbopack': ReactVersion,
   'react-server-dom-parcel': ReactVersion,
   'react-is': ReactVersion,
-  'react-reconciler': '0.33.0',
-  'react-refresh': '0.18.0',
+  'react-reconciler': '0.34.0',
+  'react-refresh': '0.19.0',
   'react-test-renderer': ReactVersion,
-  'use-subscription': '1.12.0',
-  'use-sync-external-store': '1.6.0',
-  scheduler: '0.27.0',
+  'use-subscription': '1.13.0',
+  'use-sync-external-store': '1.7.0',
+  scheduler: '0.28.0',
 };
 
 // These packages do not exist in the @canary or @latest channel, only

compiler/apps/playground/__tests__/e2e/page.spec.ts

@@ -23,7 +23,8 @@ function formatPrint(data: Array<string>): Promise<string> {
 
 async function expandConfigs(page: Page): Promise<void> {
   const expandButton = page.locator('[title="Expand config editor"]');
-  expandButton.click();
+  await expandButton.click();
+  await page.waitForSelector('.monaco-editor-config', {state: 'visible'});
 }
 
 const TEST_SOURCE = `export default function TestComponent({ x }) {

compiler/apps/playground/components/AccordionWindow.tsx

@@ -6,7 +6,13 @@
  */
 
 import {Resizable} from 're-resizable';
-import React, {useCallback} from 'react';
+import React, {
+  useId,
+  unstable_ViewTransition as ViewTransition,
+  unstable_addTransitionType as addTransitionType,
+  startTransition,
+} from 'react';
+import {EXPAND_ACCORDION_TRANSITION} from '../lib/transitionTypes';
 
 type TabsRecord = Map<string, React.ReactNode>;
 
@@ -16,21 +22,25 @@ export default function AccordionWindow(props: {
   tabsOpen: Set<string>;
   setTabsOpen: (newTab: Set<string>) => void;
   changedPasses: Set<string>;
+  isFailure: boolean;
 }): React.ReactElement {
   return (
-    <div className="flex flex-row h-full">
-      {Array.from(props.tabs.keys()).map(name => {
-        return (
-          <AccordionWindowItem
-            name={name}
-            key={name}
-            tabs={props.tabs}
-            tabsOpen={props.tabsOpen}
-            setTabsOpen={props.setTabsOpen}
-            hasChanged={props.changedPasses.has(name)}
-          />
-        );
-      })}
+    <div className="flex-1 min-w-[550px] sm:min-w-0">
+      <div className="flex flex-row h-full">
+        {Array.from(props.tabs.keys()).map(name => {
+          return (
+            <AccordionWindowItem
+              name={name}
+              key={name}
+              tabs={props.tabs}
+              tabsOpen={props.tabsOpen}
+              setTabsOpen={props.setTabsOpen}
+              hasChanged={props.changedPasses.has(name)}
+              isFailure={props.isFailure}
+            />
+          );
+        })}
+      </div>
     </div>
   );
 }
@@ -41,24 +51,32 @@ function AccordionWindowItem({
   tabsOpen,
   setTabsOpen,
   hasChanged,
+  isFailure,
 }: {
   name: string;
   tabs: TabsRecord;
   tabsOpen: Set<string>;
   setTabsOpen: (newTab: Set<string>) => void;
   hasChanged: boolean;
+  isFailure: boolean;
 }): React.ReactElement {
-  const isShow = tabsOpen.has(name);
+  const id = useId();
+  const isShow = isFailure ? name === 'Output' : tabsOpen.has(name);
 
-  const toggleTabs = useCallback(() => {
-    const nextState = new Set(tabsOpen);
-    if (nextState.has(name)) {
-      nextState.delete(name);
-    } else {
-      nextState.add(name);
-    }
-    setTabsOpen(nextState);
-  }, [tabsOpen, name, setTabsOpen]);
+  const transitionName = `accordion-window-item-${id}`;
+
+  const toggleTabs = (): void => {
+    startTransition(() => {
+      addTransitionType(EXPAND_ACCORDION_TRANSITION);
+      const nextState = new Set(tabsOpen);
+      if (nextState.has(name)) {
+        nextState.delete(name);
+      } else {
+        nextState.add(name);
+      }
+      setTabsOpen(nextState);
+    });
+  };
 
   // Replace spaces with non-breaking spaces
   const displayName = name.replace(/ /g, '\u00A0');
@@ -66,31 +84,45 @@ function AccordionWindowItem({
   return (
     <div key={name} className="flex flex-row">
       {isShow ? (
-        <Resizable className="border-r" minWidth={550} enable={{right: true}}>
-          <h2
-            title="Minimize tab"
-            aria-label="Minimize tab"
-            onClick={toggleTabs}
-            className={`p-4 duration-150 ease-in border-b cursor-pointer border-grey-200 ${
-              hasChanged ? 'font-bold' : 'font-light'
-            } text-secondary hover:text-link`}>
-            - {displayName}
-          </h2>
-          {tabs.get(name) ?? <div>No output for {name}</div>}
-        </Resizable>
+        <ViewTransition
+          name={transitionName}
+          update={{
+            [EXPAND_ACCORDION_TRANSITION]: 'expand-accordion',
+            default: 'none',
+          }}>
+          <Resizable className="border-r" minWidth={550} enable={{right: true}}>
+            <h2
+              title="Minimize tab"
+              aria-label="Minimize tab"
+              onClick={toggleTabs}
+              className={`p-4 duration-150 ease-in border-b cursor-pointer border-grey-200 ${
+                hasChanged ? 'font-bold' : 'font-light'
+              } text-secondary hover:text-link`}>
+              - {displayName}
+            </h2>
+            {tabs.get(name) ?? <div>No output for {name}</div>}
+          </Resizable>
+        </ViewTransition>
       ) : (
-        <div className="relative items-center h-full px-1 py-6 align-middle border-r border-grey-200">
-          <button
-            title={`Expand compiler tab: ${name}`}
-            aria-label={`Expand compiler tab: ${name}`}
-            style={{transform: 'rotate(90deg) translate(-50%)'}}
-            onClick={toggleTabs}
-            className={`flex-grow-0 w-5 transition-colors duration-150 ease-in ${
-              hasChanged ? 'font-bold' : 'font-light'
-            } text-secondary hover:text-link`}>
-            {displayName}
-          </button>
-        </div>
+        <ViewTransition
+          name={transitionName}
+          update={{
+            [EXPAND_ACCORDION_TRANSITION]: 'expand-accordion',
+            default: 'none',
+          }}>
+          <div className="relative items-center h-full px-1 py-6 align-middle border-r border-grey-200">
+            <button
+              title={`Expand compiler tab: ${name}`}
+              aria-label={`Expand compiler tab: ${name}`}
+              style={{transform: 'rotate(90deg) translate(-50%)'}}
+              onClick={toggleTabs}
+              className={`flex-grow-0 w-5 transition-colors duration-150 ease-in ${
+                hasChanged ? 'font-bold' : 'font-light'
+              } text-secondary hover:text-link`}>
+              {displayName}
+            </button>
+          </div>
+        </ViewTransition>
       )}
     </div>
   );

compiler/apps/playground/components/Editor/ConfigEditor.tsx

@@ -6,15 +6,20 @@
  */
 
 import MonacoEditor, {loader, type Monaco} from '@monaco-editor/react';
-import {PluginOptions} from 'babel-plugin-react-compiler';
 import type {editor} from 'monaco-editor';
 import * as monaco from 'monaco-editor';
-import React, {useState, useRef} from 'react';
+import React, {
+  useState,
+  useRef,
+  unstable_ViewTransition as ViewTransition,
+  unstable_addTransitionType as addTransitionType,
+  startTransition,
+} from 'react';
 import {Resizable} from 're-resizable';
 import {useStore, useStoreDispatch} from '../StoreContext';
-import {monacoOptions} from './monacoOptions';
+import {monacoConfigOptions} from './monacoOptions';
 import {IconChevron} from '../Icons/IconChevron';
-import prettyFormat from 'pretty-format';
+import {CONFIG_PANEL_TRANSITION} from '../../lib/transitionTypes';
 
 // @ts-expect-error - webpack asset/source loader handles .d.ts files as strings
 import compilerTypeDefs from 'babel-plugin-react-compiler/dist/index.d.ts';
@@ -22,9 +27,9 @@ import compilerTypeDefs from 'babel-plugin-react-compiler/dist/index.d.ts';
 loader.config({monaco});
 
 export default function ConfigEditor({
-  appliedOptions,
+  formattedAppliedConfig,
 }: {
-  appliedOptions: PluginOptions | null;
+  formattedAppliedConfig: string;
 }): React.ReactElement {
   const [isExpanded, setIsExpanded] = useState(false);
 
@@ -36,15 +41,27 @@ export default function ConfigEditor({
           display: isExpanded ? 'block' : 'none',
         }}>
         <ExpandedEditor
-          onToggle={setIsExpanded}
-          appliedOptions={appliedOptions}
+          onToggle={() => {
+            startTransition(() => {
+              addTransitionType(CONFIG_PANEL_TRANSITION);
+              setIsExpanded(false);
+            });
+          }}
+          formattedAppliedConfig={formattedAppliedConfig}
         />
       </div>
       <div
         style={{
           display: !isExpanded ? 'block' : 'none',
         }}>
-        <CollapsedEditor onToggle={setIsExpanded} />
+        <CollapsedEditor
+          onToggle={() => {
+            startTransition(() => {
+              addTransitionType(CONFIG_PANEL_TRANSITION);
+              setIsExpanded(true);
+            });
+          }}
+        />
       </div>
     </>
   );
@@ -52,10 +69,10 @@ export default function ConfigEditor({
 
 function ExpandedEditor({
   onToggle,
-  appliedOptions,
+  formattedAppliedConfig,
 }: {
   onToggle: (expanded: boolean) => void;
-  appliedOptions: PluginOptions | null;
+  formattedAppliedConfig: string;
 }): React.ReactElement {
   const store = useStore();
   const dispatchStore = useStoreDispatch();
@@ -103,98 +120,78 @@ function ExpandedEditor({
     });
   };
 
-  const formattedAppliedOptions = appliedOptions
-    ? prettyFormat(appliedOptions, {
-        printFunctionName: false,
-        printBasicPrototype: false,
-      })
-    : 'Invalid configs';
-
   return (
-    <Resizable
-      minWidth={300}
-      maxWidth={600}
-      defaultSize={{width: 350}}
-      enable={{right: true, bottom: false}}>
-      <div className="bg-blue-10 relative h-full flex flex-col !h-[calc(100vh_-_3.5rem)] border border-gray-300">
-        <div
-          className="absolute w-8 h-16 bg-blue-10 rounded-r-full flex items-center justify-center z-[2] cursor-pointer border border-l-0 border-gray-300"
-          title="Minimize config editor"
-          onClick={() => onToggle(false)}
-          style={{
-            top: '50%',
-            marginTop: '-32px',
-            right: '-32px',
-            borderTopLeftRadius: 0,
-            borderBottomLeftRadius: 0,
-          }}>
-          <IconChevron displayDirection="left" className="text-blue-50" />
-        </div>
+    <ViewTransition
+      update={{[CONFIG_PANEL_TRANSITION]: 'slide-in', default: 'none'}}>
+      <Resizable
+        minWidth={300}
+        maxWidth={600}
+        defaultSize={{width: 350}}
+        enable={{right: true, bottom: false}}>
+        <div className="bg-blue-10 relative h-full flex flex-col !h-[calc(100vh_-_3.5rem)] border border-gray-300">
+          <div
+            className="absolute w-8 h-16 bg-blue-10 rounded-r-full flex items-center justify-center z-[2] cursor-pointer border border-l-0 border-gray-300"
+            title="Minimize config editor"
+            onClick={onToggle}
+            style={{
+              top: '50%',
+              marginTop: '-32px',
+              right: '-32px',
+              borderTopLeftRadius: 0,
+              borderBottomLeftRadius: 0,
+            }}>
+            <IconChevron displayDirection="left" className="text-blue-50" />
+          </div>
 
-        <div className="flex-1 flex flex-col m-2 mb-2">
-          <div className="pb-2">
-            <h2 className="inline-block text-blue-50 py-1.5 px-1.5 xs:px-3 sm:px-4 text-sm">
-              Config Overrides
-            </h2>
+          <div className="flex-1 flex flex-col m-2 mb-2">
+            <div className="pb-2">
+              <h2 className="inline-block text-blue-50 py-1.5 px-1.5 xs:px-3 sm:px-4 text-sm">
+                Config Overrides
+              </h2>
+            </div>
+            <div className="flex-1 border border-gray-300">
+              <MonacoEditor
+                path={'config.ts'}
+                language={'typescript'}
+                value={store.config}
+                onMount={handleMount}
+                onChange={handleChange}
+                loading={''}
+                className="monaco-editor-config"
+                options={monacoConfigOptions}
+              />
+            </div>
           </div>
-          <div className="flex-1 rounded-lg overflow-hidden border border-gray-300">
-            <MonacoEditor
-              path={'config.ts'}
-              language={'typescript'}
-              value={store.config}
-              onMount={handleMount}
-              onChange={handleChange}
-              loading={''}
-              className="monaco-editor-config"
-              options={{
-                ...monacoOptions,
-                lineNumbers: 'off',
-                renderLineHighlight: 'none',
-                overviewRulerBorder: false,
-                overviewRulerLanes: 0,
-                fontSize: 12,
-                scrollBeyondLastLine: false,
-                glyphMargin: false,
-              }}
-            />
+          <div className="flex-1 flex flex-col m-2">
+            <div className="pb-2">
+              <h2 className="inline-block text-blue-50 py-1.5 px-1.5 xs:px-3 sm:px-4 text-sm">
+                Applied Configs
+              </h2>
+            </div>
+            <div className="flex-1 border border-gray-300">
+              <MonacoEditor
+                path={'applied-config.js'}
+                language={'javascript'}
+                value={formattedAppliedConfig}
+                loading={''}
+                className="monaco-editor-applied-config"
+                options={{
+                  ...monacoConfigOptions,
+                  readOnly: true,
+                }}
+              />
+            </div>
           </div>
         </div>
-        <div className="flex-1 flex flex-col m-2">
-          <div className="pb-2">
-            <h2 className="inline-block text-blue-50 py-1.5 px-1.5 xs:px-3 sm:px-4 text-sm">
-              Applied Configs
-            </h2>
-          </div>
-          <div className="flex-1 rounded-lg overflow-hidden border border-gray-300">
-            <MonacoEditor
-              path={'applied-config.js'}
-              language={'javascript'}
-              value={formattedAppliedOptions}
-              loading={''}
-              className="monaco-editor-applied-config"
-              options={{
-                ...monacoOptions,
-                lineNumbers: 'off',
-                renderLineHighlight: 'none',
-                overviewRulerBorder: false,
-                overviewRulerLanes: 0,
-                fontSize: 12,
-                scrollBeyondLastLine: false,
-                readOnly: true,
-                glyphMargin: false,
-              }}
-            />
-          </div>
-        </div>
-      </div>
-    </Resizable>
+      </Resizable>
+    </ViewTransition>
   );
 }
 
 function CollapsedEditor({
   onToggle,
 }: {
-  onToggle: (expanded: boolean) => void;
+  onToggle: () => void;
 }): React.ReactElement {
   return (
     <div
@@ -203,7 +200,7 @@ function CollapsedEditor({
       <div
         className="absolute w-10 h-16 bg-blue-10 hover:translate-x-2 transition-transform rounded-r-full flex items-center justify-center z-[2] cursor-pointer border border-gray-300"
         title="Expand config editor"
-        onClick={() => onToggle(true)}
+        onClick={onToggle}
         style={{
           top: '50%',
           marginTop: '-32px',

compiler/apps/playground/components/Editor/EditorImpl.tsx

@@ -5,312 +5,17 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {parse as babelParse, ParseResult} from '@babel/parser';
-import * as HermesParser from 'hermes-parser';
-import * as t from '@babel/types';
-import BabelPluginReactCompiler, {
-  CompilerError,
+import {
   CompilerErrorDetail,
   CompilerDiagnostic,
-  Effect,
-  ErrorCategory,
-  parseConfigPragmaForTests,
-  ValueKind,
-  type Hook,
-  PluginOptions,
-  CompilerPipelineValue,
-  parsePluginOptions,
-  printReactiveFunctionWithOutlined,
-  printFunctionWithOutlined,
-  type LoggerEvent,
 } from 'babel-plugin-react-compiler';
-import {useDeferredValue, useMemo} from 'react';
+import {useDeferredValue, useMemo, useState} from 'react';
 import {useStore} from '../StoreContext';
 import ConfigEditor from './ConfigEditor';
 import Input from './Input';
-import {
-  CompilerOutput,
-  CompilerTransformOutput,
-  default as Output,
-  PrintedCompilerPipelineValue,
-} from './Output';
-import {transformFromAstSync} from '@babel/core';
-
-function parseInput(
-  input: string,
-  language: 'flow' | 'typescript',
-): ParseResult<t.File> {
-  // Extract the first line to quickly check for custom test directives
-  if (language === 'flow') {
-    return HermesParser.parse(input, {
-      babel: true,
-      flow: 'all',
-      sourceType: 'module',
-      enableExperimentalComponentSyntax: true,
-    });
-  } else {
-    return babelParse(input, {
-      plugins: ['typescript', 'jsx'],
-      sourceType: 'module',
-    }) as ParseResult<t.File>;
-  }
-}
-
-function invokeCompiler(
-  source: string,
-  language: 'flow' | 'typescript',
-  options: PluginOptions,
-): CompilerTransformOutput {
-  const ast = parseInput(source, language);
-  let result = transformFromAstSync(ast, source, {
-    filename: '_playgroundFile.js',
-    highlightCode: false,
-    retainLines: true,
-    plugins: [[BabelPluginReactCompiler, options]],
-    ast: true,
-    sourceType: 'module',
-    configFile: false,
-    sourceMaps: true,
-    babelrc: false,
-  });
-  if (result?.ast == null || result?.code == null || result?.map == null) {
-    throw new Error('Expected successful compilation');
-  }
-  return {
-    code: result.code,
-    sourceMaps: result.map,
-    language,
-  };
-}
-
-const COMMON_HOOKS: Array<[string, Hook]> = [
-  [
-    'useFragment',
-    {
-      valueKind: ValueKind.Frozen,
-      effectKind: Effect.Freeze,
-      noAlias: true,
-      transitiveMixedData: true,
-    },
-  ],
-  [
-    'usePaginationFragment',
-    {
-      valueKind: ValueKind.Frozen,
-      effectKind: Effect.Freeze,
-      noAlias: true,
-      transitiveMixedData: true,
-    },
-  ],
-  [
-    'useRefetchableFragment',
-    {
-      valueKind: ValueKind.Frozen,
-      effectKind: Effect.Freeze,
-      noAlias: true,
-      transitiveMixedData: true,
-    },
-  ],
-  [
-    'useLazyLoadQuery',
-    {
-      valueKind: ValueKind.Frozen,
-      effectKind: Effect.Freeze,
-      noAlias: true,
-      transitiveMixedData: true,
-    },
-  ],
-  [
-    'usePreloadedQuery',
-    {
-      valueKind: ValueKind.Frozen,
-      effectKind: Effect.Freeze,
-      noAlias: true,
-      transitiveMixedData: true,
-    },
-  ],
-];
-
-function parseOptions(
-  source: string,
-  mode: 'compiler' | 'linter',
-  configOverrides: string,
-): PluginOptions {
-  // Extract the first line to quickly check for custom test directives
-  const pragma = source.substring(0, source.indexOf('\n'));
-
-  const parsedPragmaOptions = parseConfigPragmaForTests(pragma, {
-    compilationMode: 'infer',
-    environment:
-      mode === 'linter'
-        ? {
-            // enabled in compiler
-            validateRefAccessDuringRender: false,
-            // enabled in linter
-            validateNoSetStateInRender: true,
-            validateNoSetStateInEffects: true,
-            validateNoJSXInTryStatements: true,
-            validateNoImpureFunctionsInRender: true,
-            validateStaticComponents: true,
-            validateNoFreezingKnownMutableFunctions: true,
-            validateNoVoidUseMemo: true,
-          }
-        : {
-            /* use defaults for compiler mode */
-          },
-  });
-
-  // Parse config overrides from config editor
-  let configOverrideOptions: any = {};
-  const configMatch = configOverrides.match(/^\s*import.*?\n\n\((.*)\)/s);
-  if (configOverrides.trim()) {
-    if (configMatch && configMatch[1]) {
-      const configString = configMatch[1].replace(/satisfies.*$/, '').trim();
-      configOverrideOptions = new Function(`return (${configString})`)();
-    } else {
-      throw new Error('Invalid override format');
-    }
-  }
-
-  const opts: PluginOptions = parsePluginOptions({
-    ...parsedPragmaOptions,
-    ...configOverrideOptions,
-    environment: {
-      ...parsedPragmaOptions.environment,
-      ...configOverrideOptions.environment,
-      customHooks: new Map([...COMMON_HOOKS]),
-    },
-  });
-
-  return opts;
-}
-
-function compile(
-  source: string,
-  mode: 'compiler' | 'linter',
-  configOverrides: string,
-): [CompilerOutput, 'flow' | 'typescript', PluginOptions | null] {
-  const results = new Map<string, Array<PrintedCompilerPipelineValue>>();
-  const error = new CompilerError();
-  const otherErrors: Array<CompilerErrorDetail | CompilerDiagnostic> = [];
-  const upsert: (result: PrintedCompilerPipelineValue) => void = result => {
-    const entry = results.get(result.name);
-    if (Array.isArray(entry)) {
-      entry.push(result);
-    } else {
-      results.set(result.name, [result]);
-    }
-  };
-  let language: 'flow' | 'typescript';
-  if (source.match(/\@flow/)) {
-    language = 'flow';
-  } else {
-    language = 'typescript';
-  }
-  let transformOutput;
-
-  let baseOpts: PluginOptions | null = null;
-  try {
-    baseOpts = parseOptions(source, mode, configOverrides);
-  } catch (err) {
-    error.details.push(
-      new CompilerErrorDetail({
-        category: ErrorCategory.Config,
-        reason: `Unexpected failure when transforming configs! \n${err}`,
-        loc: null,
-        suggestions: null,
-      }),
-    );
-  }
-  if (baseOpts) {
-    try {
-      const logIR = (result: CompilerPipelineValue): void => {
-        switch (result.kind) {
-          case 'ast': {
-            break;
-          }
-          case 'hir': {
-            upsert({
-              kind: 'hir',
-              fnName: result.value.id,
-              name: result.name,
-              value: printFunctionWithOutlined(result.value),
-            });
-            break;
-          }
-          case 'reactive': {
-            upsert({
-              kind: 'reactive',
-              fnName: result.value.id,
-              name: result.name,
-              value: printReactiveFunctionWithOutlined(result.value),
-            });
-            break;
-          }
-          case 'debug': {
-            upsert({
-              kind: 'debug',
-              fnName: null,
-              name: result.name,
-              value: result.value,
-            });
-            break;
-          }
-          default: {
-            const _: never = result;
-            throw new Error(`Unhandled result ${result}`);
-          }
-        }
-      };
-      // Add logger options to the parsed options
-      const opts = {
-        ...baseOpts,
-        logger: {
-          debugLogIRs: logIR,
-          logEvent: (_filename: string | null, event: LoggerEvent): void => {
-            if (event.kind === 'CompileError') {
-              otherErrors.push(event.detail);
-            }
-          },
-        },
-      };
-      transformOutput = invokeCompiler(source, language, opts);
-    } catch (err) {
-      /**
-       * error might be an invariant violation or other runtime error
-       * (i.e. object shape that is not CompilerError)
-       */
-      if (err instanceof CompilerError && err.details.length > 0) {
-        error.merge(err);
-      } else {
-        /**
-         * Handle unexpected failures by logging (to get a stack trace)
-         * and reporting
-         */
-        error.details.push(
-          new CompilerErrorDetail({
-            category: ErrorCategory.Invariant,
-            reason: `Unexpected failure when transforming input! \n${err}`,
-            loc: null,
-            suggestions: null,
-          }),
-        );
-      }
-    }
-  }
-  // Only include logger errors if there weren't other errors
-  if (!error.hasErrors() && otherErrors.length !== 0) {
-    otherErrors.forEach(e => error.details.push(e));
-  }
-  if (error.hasErrors()) {
-    return [{kind: 'err', results, error}, language, baseOpts];
-  }
-  return [
-    {kind: 'ok', results, transformOutput, errors: error.details},
-    language,
-    baseOpts,
-  ];
-}
+import {CompilerOutput, default as Output} from './Output';
+import {compile} from '../../lib/compilation';
+import prettyFormat from 'pretty-format';
 
 export default function Editor(): JSX.Element {
   const store = useStore();
@@ -323,6 +28,7 @@ export default function Editor(): JSX.Element {
     () => compile(deferredStore.source, 'linter', deferredStore.config),
     [deferredStore.source, deferredStore.config],
   );
+  const [formattedAppliedConfig, setFormattedAppliedConfig] = useState('');
 
   let mergedOutput: CompilerOutput;
   let errors: Array<CompilerErrorDetail | CompilerDiagnostic>;
@@ -336,19 +42,26 @@ export default function Editor(): JSX.Element {
     mergedOutput = compilerOutput;
     errors = compilerOutput.error.details;
   }
+
+  if (appliedOptions) {
+    const formatted = prettyFormat(appliedOptions, {
+      printFunctionName: false,
+      printBasicPrototype: false,
+    });
+    if (formatted !== formattedAppliedConfig) {
+      setFormattedAppliedConfig(formatted);
+    }
+  }
+
   return (
     <>
       <div className="relative flex top-14">
         <div className="flex-shrink-0">
-          <ConfigEditor appliedOptions={appliedOptions} />
+          <ConfigEditor formattedAppliedConfig={formattedAppliedConfig} />
         </div>
         <div className="flex flex-1 min-w-0">
-          <div className="flex-1 min-w-[550px] sm:min-w-0">
-            <Input language={language} errors={errors} />
-          </div>
-          <div className="flex-1 min-w-[550px] sm:min-w-0">
-            <Output store={deferredStore} compilerOutput={mergedOutput} />
-          </div>
+          <Input language={language} errors={errors} />
+          <Output store={deferredStore} compilerOutput={mergedOutput} />
         </div>
       </div>
     </>

compiler/apps/playground/components/Editor/Input.tsx

@@ -13,11 +13,17 @@ import {
 import invariant from 'invariant';
 import type {editor} from 'monaco-editor';
 import * as monaco from 'monaco-editor';
-import {useEffect, useState} from 'react';
+import {
+  useEffect,
+  useState,
+  unstable_ViewTransition as ViewTransition,
+} from 'react';
 import {renderReactCompilerMarkers} from '../../lib/reactCompilerMonacoDiagnostics';
 import {useStore, useStoreDispatch} from '../StoreContext';
 import TabbedWindow from '../TabbedWindow';
 import {monacoOptions} from './monacoOptions';
+import {CONFIG_PANEL_TRANSITION} from '../../lib/transitionTypes';
+
 // @ts-expect-error TODO: Make TS recognize .d.ts files, in addition to loading them with webpack.
 import React$Types from '../../node_modules/@types/react/index.d.ts';
 
@@ -155,9 +161,13 @@ export default function Input({errors, language}: Props): JSX.Element {
   const [activeTab, setActiveTab] = useState('Input');
 
   return (
-    <div className="relative flex flex-col flex-none border-r border-gray-200">
-      <div className="!h-[calc(100vh_-_3.5rem)]">
-        <div className="flex flex-col h-full">
+    <ViewTransition
+      update={{
+        [CONFIG_PANEL_TRANSITION]: 'container',
+        default: 'none',
+      }}>
+      <div className="flex-1 min-w-[550px] sm:min-w-0">
+        <div className="flex flex-col h-full !h-[calc(100vh_-_3.5rem)] border-r border-gray-200">
           <TabbedWindow
             tabs={tabs}
             activeTab={activeTab}
@@ -165,6 +175,6 @@ export default function Input({errors, language}: Props): JSX.Element {
           />
         </div>
       </div>
-    </div>
+    </ViewTransition>
   );
 }

compiler/apps/playground/components/Editor/Output.tsx

@@ -20,11 +20,22 @@ import parserBabel from 'prettier/plugins/babel';
 import * as prettierPluginEstree from 'prettier/plugins/estree';
 import * as prettier from 'prettier/standalone';
 import {type Store} from '../../lib/stores';
-import {memo, ReactNode, use, useState, Suspense} from 'react';
+import {
+  memo,
+  ReactNode,
+  use,
+  useState,
+  Suspense,
+  unstable_ViewTransition as ViewTransition,
+} from 'react';
 import AccordionWindow from '../AccordionWindow';
 import TabbedWindow from '../TabbedWindow';
 import {monacoOptions} from './monacoOptions';
 import {BabelFileResult} from '@babel/core';
+import {
+  CONFIG_PANEL_TRANSITION,
+  TOGGLE_INTERNALS_TRANSITION,
+} from '../../lib/transitionTypes';
 import {LRUCache} from 'lru-cache';
 
 const MemoizedOutput = memo(Output);
@@ -254,14 +265,8 @@ function OutputContent({store, compilerOutput}: Props): JSX.Element {
    * Update the active tab back to the output or errors tab when the compilation state
    * changes between success/failure.
    */
-  const [previousOutputKind, setPreviousOutputKind] = useState(
-    compilerOutput.kind,
-  );
-  if (compilerOutput.kind !== previousOutputKind) {
-    setPreviousOutputKind(compilerOutput.kind);
-    setTabsOpen(new Set(['Output']));
-    setActiveTab('Output');
-  }
+
+  const isFailure = compilerOutput.kind !== 'ok';
   const changedPasses: Set<string> = new Set(['Output', 'HIR']); // Initial and final passes should always be bold
   let lastResult: string = '';
   for (const [passName, results] of compilerOutput.results) {
@@ -280,22 +285,39 @@ function OutputContent({store, compilerOutput}: Props): JSX.Element {
 
   if (!store.showInternals) {
     return (
-      <TabbedWindow
-        tabs={tabs}
-        activeTab={activeTab}
-        onTabChange={setActiveTab}
-      />
+      <ViewTransition
+        update={{
+          [CONFIG_PANEL_TRANSITION]: 'container',
+          [TOGGLE_INTERNALS_TRANSITION]: '',
+          default: 'none',
+        }}>
+        <TabbedWindow
+          tabs={tabs}
+          activeTab={activeTab}
+          onTabChange={setActiveTab}
+          // Display the Output tab on compilation failure
+          activeTabOverride={isFailure ? 'Output' : undefined}
+        />
+      </ViewTransition>
     );
   }
 
   return (
-    <AccordionWindow
-      defaultTab={store.showInternals ? 'HIR' : 'Output'}
-      setTabsOpen={setTabsOpen}
-      tabsOpen={tabsOpen}
-      tabs={tabs}
-      changedPasses={changedPasses}
-    />
+    <ViewTransition
+      update={{
+        [CONFIG_PANEL_TRANSITION]: 'accordion-container',
+        [TOGGLE_INTERNALS_TRANSITION]: '',
+        default: 'none',
+      }}>
+      <AccordionWindow
+        defaultTab={store.showInternals ? 'HIR' : 'Output'}
+        setTabsOpen={setTabsOpen}
+        tabsOpen={tabsOpen}
+        tabs={tabs}
+        changedPasses={changedPasses}
+        isFailure={isFailure}
+      />
+    </ViewTransition>
   );
 }
 
@@ -350,12 +372,18 @@ function TextTabContent({
           loading={''}
           options={{
             ...monacoOptions,
+            scrollbar: {
+              vertical: 'hidden',
+            },
+            dimension: {
+              width: 0,
+              height: 0,
+            },
             readOnly: true,
             lineNumbers: 'off',
             glyphMargin: false,
             // Undocumented see https://github.com/Microsoft/vscode/issues/30795#issuecomment-410998882
-            lineDecorationsWidth: 0,
-            lineNumbersMinChars: 0,
+            overviewRulerLanes: 0,
           }}
         />
       ) : (

compiler/apps/playground/components/Editor/monacoOptions.ts

@@ -32,3 +32,14 @@ export const monacoOptions: Partial<EditorProps['options']> = {
 
   tabSize: 2,
 };
+
+export const monacoConfigOptions: Partial<EditorProps['options']> = {
+  ...monacoOptions,
+  lineNumbers: 'off',
+  renderLineHighlight: 'none',
+  overviewRulerBorder: false,
+  overviewRulerLanes: 0,
+  fontSize: 12,
+  scrollBeyondLastLine: false,
+  glyphMargin: false,
+};

compiler/apps/playground/components/Header.tsx

@@ -10,11 +10,16 @@ import {CheckIcon} from '@heroicons/react/solid';
 import clsx from 'clsx';
 import Link from 'next/link';
 import {useSnackbar} from 'notistack';
-import {useState} from 'react';
+import {
+  useState,
+  startTransition,
+  unstable_addTransitionType as addTransitionType,
+} from 'react';
 import {defaultStore} from '../lib/defaultStore';
 import {IconGitHub} from './Icons/IconGitHub';
 import Logo from './Logo';
 import {useStore, useStoreDispatch} from './StoreContext';
+import {TOGGLE_INTERNALS_TRANSITION} from '../lib/transitionTypes';
 
 export default function Header(): JSX.Element {
   const [showCheck, setShowCheck] = useState(false);
@@ -62,7 +67,12 @@ export default function Header(): JSX.Element {
             <input
               type="checkbox"
               checked={store.showInternals}
-              onChange={() => dispatchStore({type: 'toggleInternals'})}
+              onChange={() =>
+                startTransition(() => {
+                  addTransitionType(TOGGLE_INTERNALS_TRANSITION);
+                  dispatchStore({type: 'toggleInternals'});
+                })
+              }
               className="absolute opacity-0 cursor-pointer h-full w-full m-0"
             />
             <span

compiler/apps/playground/components/TabbedWindow.tsx

@@ -4,39 +4,81 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  */
-import React from 'react';
+import React, {
+  startTransition,
+  useId,
+  unstable_ViewTransition as ViewTransition,
+  unstable_addTransitionType as addTransitionType,
+} from 'react';
 import clsx from 'clsx';
+import {TOGGLE_TAB_TRANSITION} from '../lib/transitionTypes';
 
 export default function TabbedWindow({
   tabs,
   activeTab,
   onTabChange,
+  activeTabOverride,
 }: {
   tabs: Map<string, React.ReactNode>;
   activeTab: string;
   onTabChange: (tab: string) => void;
+  activeTabOverride?: string;
 }): React.ReactElement {
+  const currentActiveTab = activeTabOverride ? activeTabOverride : activeTab;
+
+  const id = useId();
+  const transitionName = `tab-highlight-${id}`;
+
+  const handleTabChange = (tab: string): void => {
+    startTransition(() => {
+      addTransitionType(TOGGLE_TAB_TRANSITION);
+      onTabChange(tab);
+    });
+  };
+
   return (
-    <div className="flex flex-col h-full max-w-full">
-      <div className="flex p-2 flex-shrink-0">
-        {Array.from(tabs.keys()).map(tab => {
-          const isActive = activeTab === tab;
-          return (
-            <button
-              key={tab}
-              onClick={() => onTabChange(tab)}
-              className={clsx(
-                'active:scale-95 transition-transform py-1.5 px-1.5 xs:px-3 sm:px-4 rounded-full text-sm',
-                !isActive && 'hover:bg-primary/5',
-                isActive && 'bg-highlight text-link',
-              )}>
-              {tab}
-            </button>
-          );
-        })}
-      </div>
-      <div className="flex-1 overflow-hidden w-full h-full">
-        {tabs.get(activeTab)}
+    <div className="flex-1 min-w-[550px] sm:min-w-0">
+      <div className="flex flex-col h-full max-w-full">
+        <div className="flex p-2 flex-shrink-0">
+          {Array.from(tabs.keys()).map(tab => {
+            const isActive = currentActiveTab === tab;
+            return (
+              <button
+                key={tab}
+                onClick={() => handleTabChange(tab)}
+                className={clsx(
+                  'transition-transform py-1.5 px-1.5 xs:px-3 sm:px-4 rounded-full text-sm relative',
+                  isActive ? 'text-link' : 'hover:bg-primary/5',
+                )}>
+                {isActive && (
+                  <ViewTransition
+                    name={transitionName}
+                    enter={{default: 'none'}}
+                    exit={{default: 'none'}}
+                    share={{
+                      [TOGGLE_TAB_TRANSITION]: 'tab-highlight',
+                      default: 'none',
+                    }}
+                    update={{default: 'none'}}>
+                    <div className="absolute inset-0 bg-highlight rounded-full" />
+                  </ViewTransition>
+                )}
+                <ViewTransition
+                  enter={{default: 'none'}}
+                  exit={{default: 'none'}}
+                  update={{
+                    [TOGGLE_TAB_TRANSITION]: 'tab-text',
+                    default: 'none',
+                  }}>
+                  <span className="relative z-1">{tab}</span>
+                </ViewTransition>
+              </button>
+            );
+          })}
+        </div>
+        <div className="flex-1 overflow-hidden w-full h-full">
+          {tabs.get(currentActiveTab)}
+        </div>
       </div>
     </div>
   );

compiler/apps/playground/lib/compilation.ts

@@ -0,0 +1,308 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import {parse as babelParse, ParseResult} from '@babel/parser';
+import * as HermesParser from 'hermes-parser';
+import * as t from '@babel/types';
+import BabelPluginReactCompiler, {
+  CompilerError,
+  CompilerErrorDetail,
+  CompilerDiagnostic,
+  Effect,
+  ErrorCategory,
+  parseConfigPragmaForTests,
+  ValueKind,
+  type Hook,
+  PluginOptions,
+  CompilerPipelineValue,
+  parsePluginOptions,
+  printReactiveFunctionWithOutlined,
+  printFunctionWithOutlined,
+  type LoggerEvent,
+} from 'babel-plugin-react-compiler';
+import {transformFromAstSync} from '@babel/core';
+import type {
+  CompilerOutput,
+  CompilerTransformOutput,
+  PrintedCompilerPipelineValue,
+} from '../components/Editor/Output';
+
+function parseInput(
+  input: string,
+  language: 'flow' | 'typescript',
+): ParseResult<t.File> {
+  // Extract the first line to quickly check for custom test directives
+  if (language === 'flow') {
+    return HermesParser.parse(input, {
+      babel: true,
+      flow: 'all',
+      sourceType: 'module',
+      enableExperimentalComponentSyntax: true,
+    });
+  } else {
+    return babelParse(input, {
+      plugins: ['typescript', 'jsx'],
+      sourceType: 'module',
+    }) as ParseResult<t.File>;
+  }
+}
+
+function invokeCompiler(
+  source: string,
+  language: 'flow' | 'typescript',
+  options: PluginOptions,
+): CompilerTransformOutput {
+  const ast = parseInput(source, language);
+  let result = transformFromAstSync(ast, source, {
+    filename: '_playgroundFile.js',
+    highlightCode: false,
+    retainLines: true,
+    plugins: [[BabelPluginReactCompiler, options]],
+    ast: true,
+    sourceType: 'module',
+    configFile: false,
+    sourceMaps: true,
+    babelrc: false,
+  });
+  if (result?.ast == null || result?.code == null || result?.map == null) {
+    throw new Error('Expected successful compilation');
+  }
+  return {
+    code: result.code,
+    sourceMaps: result.map,
+    language,
+  };
+}
+
+const COMMON_HOOKS: Array<[string, Hook]> = [
+  [
+    'useFragment',
+    {
+      valueKind: ValueKind.Frozen,
+      effectKind: Effect.Freeze,
+      noAlias: true,
+      transitiveMixedData: true,
+    },
+  ],
+  [
+    'usePaginationFragment',
+    {
+      valueKind: ValueKind.Frozen,
+      effectKind: Effect.Freeze,
+      noAlias: true,
+      transitiveMixedData: true,
+    },
+  ],
+  [
+    'useRefetchableFragment',
+    {
+      valueKind: ValueKind.Frozen,
+      effectKind: Effect.Freeze,
+      noAlias: true,
+      transitiveMixedData: true,
+    },
+  ],
+  [
+    'useLazyLoadQuery',
+    {
+      valueKind: ValueKind.Frozen,
+      effectKind: Effect.Freeze,
+      noAlias: true,
+      transitiveMixedData: true,
+    },
+  ],
+  [
+    'usePreloadedQuery',
+    {
+      valueKind: ValueKind.Frozen,
+      effectKind: Effect.Freeze,
+      noAlias: true,
+      transitiveMixedData: true,
+    },
+  ],
+];
+
+function parseOptions(
+  source: string,
+  mode: 'compiler' | 'linter',
+  configOverrides: string,
+): PluginOptions {
+  // Extract the first line to quickly check for custom test directives
+  const pragma = source.substring(0, source.indexOf('\n'));
+
+  const parsedPragmaOptions = parseConfigPragmaForTests(pragma, {
+    compilationMode: 'infer',
+    environment:
+      mode === 'linter'
+        ? {
+            // enabled in compiler
+            validateRefAccessDuringRender: false,
+            // enabled in linter
+            validateNoSetStateInRender: true,
+            validateNoSetStateInEffects: true,
+            validateNoJSXInTryStatements: true,
+            validateNoImpureFunctionsInRender: true,
+            validateStaticComponents: true,
+            validateNoFreezingKnownMutableFunctions: true,
+            validateNoVoidUseMemo: true,
+          }
+        : {
+            /* use defaults for compiler mode */
+          },
+  });
+
+  // Parse config overrides from config editor
+  let configOverrideOptions: any = {};
+  const configMatch = configOverrides.match(/^\s*import.*?\n\n\((.*)\)/s);
+  if (configOverrides.trim()) {
+    if (configMatch && configMatch[1]) {
+      const configString = configMatch[1].replace(/satisfies.*$/, '').trim();
+      configOverrideOptions = new Function(`return (${configString})`)();
+    } else {
+      throw new Error('Invalid override format');
+    }
+  }
+
+  const opts: PluginOptions = parsePluginOptions({
+    ...parsedPragmaOptions,
+    ...configOverrideOptions,
+    environment: {
+      ...parsedPragmaOptions.environment,
+      ...configOverrideOptions.environment,
+      customHooks: new Map([...COMMON_HOOKS]),
+    },
+  });
+
+  return opts;
+}
+
+export function compile(
+  source: string,
+  mode: 'compiler' | 'linter',
+  configOverrides: string,
+): [CompilerOutput, 'flow' | 'typescript', PluginOptions | null] {
+  const results = new Map<string, Array<PrintedCompilerPipelineValue>>();
+  const error = new CompilerError();
+  const otherErrors: Array<CompilerErrorDetail | CompilerDiagnostic> = [];
+  const upsert: (result: PrintedCompilerPipelineValue) => void = result => {
+    const entry = results.get(result.name);
+    if (Array.isArray(entry)) {
+      entry.push(result);
+    } else {
+      results.set(result.name, [result]);
+    }
+  };
+  let language: 'flow' | 'typescript';
+  if (source.match(/\@flow/)) {
+    language = 'flow';
+  } else {
+    language = 'typescript';
+  }
+  let transformOutput;
+
+  let baseOpts: PluginOptions | null = null;
+  try {
+    baseOpts = parseOptions(source, mode, configOverrides);
+  } catch (err) {
+    error.details.push(
+      new CompilerErrorDetail({
+        category: ErrorCategory.Config,
+        reason: `Unexpected failure when transforming configs! \n${err}`,
+        loc: null,
+        suggestions: null,
+      }),
+    );
+  }
+  if (baseOpts) {
+    try {
+      const logIR = (result: CompilerPipelineValue): void => {
+        switch (result.kind) {
+          case 'ast': {
+            break;
+          }
+          case 'hir': {
+            upsert({
+              kind: 'hir',
+              fnName: result.value.id,
+              name: result.name,
+              value: printFunctionWithOutlined(result.value),
+            });
+            break;
+          }
+          case 'reactive': {
+            upsert({
+              kind: 'reactive',
+              fnName: result.value.id,
+              name: result.name,
+              value: printReactiveFunctionWithOutlined(result.value),
+            });
+            break;
+          }
+          case 'debug': {
+            upsert({
+              kind: 'debug',
+              fnName: null,
+              name: result.name,
+              value: result.value,
+            });
+            break;
+          }
+          default: {
+            const _: never = result;
+            throw new Error(`Unhandled result ${result}`);
+          }
+        }
+      };
+      // Add logger options to the parsed options
+      const opts = {
+        ...baseOpts,
+        logger: {
+          debugLogIRs: logIR,
+          logEvent: (_filename: string | null, event: LoggerEvent): void => {
+            if (event.kind === 'CompileError') {
+              otherErrors.push(event.detail);
+            }
+          },
+        },
+      };
+      transformOutput = invokeCompiler(source, language, opts);
+    } catch (err) {
+      /**
+       * error might be an invariant violation or other runtime error
+       * (i.e. object shape that is not CompilerError)
+       */
+      if (err instanceof CompilerError && err.details.length > 0) {
+        error.merge(err);
+      } else {
+        /**
+         * Handle unexpected failures by logging (to get a stack trace)
+         * and reporting
+         */
+        error.details.push(
+          new CompilerErrorDetail({
+            category: ErrorCategory.Invariant,
+            reason: `Unexpected failure when transforming input! \n${err}`,
+            loc: null,
+            suggestions: null,
+          }),
+        );
+      }
+    }
+  }
+  // Only include logger errors if there weren't other errors
+  if (!error.hasErrors() && otherErrors.length !== 0) {
+    otherErrors.forEach(e => error.details.push(e));
+  }
+  if (error.hasErrors()) {
+    return [{kind: 'err', results, error}, language, baseOpts];
+  }
+  return [
+    {kind: 'ok', results, transformOutput, errors: error.details},
+    language,
+    baseOpts,
+  ];
+}

compiler/apps/playground/lib/transitionTypes.ts

@@ -0,0 +1,11 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+export const CONFIG_PANEL_TRANSITION = 'config-panel';
+export const TOGGLE_TAB_TRANSITION = 'toggle-tab';
+export const TOGGLE_INTERNALS_TRANSITION = 'toggle-internals';
+export const EXPAND_ACCORDION_TRANSITION = 'open-accordion';

compiler/apps/playground/next.config.js

@@ -11,6 +11,7 @@ const path = require('path');
 const nextConfig = {
   experimental: {
     reactCompiler: true,
+    viewTransition: true,
   },
   reactStrictMode: true,
   webpack: (config, options) => {

compiler/apps/playground/styles/globals.css

@@ -69,3 +69,66 @@
     scrollbar-width: none; /* Firefox */
   }
 }
+
+::view-transition-old(.slide-in) {
+  animation-name: slideOutLeft;
+}
+::view-transition-new(.slide-in) {
+  animation-name: slideInLeft;
+}
+::view-transition-group(.slide-in) {
+  z-index: 1;
+}
+
+@keyframes slideOutLeft {
+  from {
+    transform: translateX(0);
+  }
+  to {
+    transform: translateX(-100%);
+  }
+}
+@keyframes slideInLeft {
+  from {
+    transform: translateX(-100%);
+  }
+  to {
+    transform: translateX(0);
+  }
+}
+
+::view-transition-old(.container),
+::view-transition-new(.container) {
+  height: 100%;
+}
+
+::view-transition-old(.accordion-container),
+::view-transition-new(.accordion-container) {
+  height: 100%;
+  object-fit: none;
+  object-position: left;
+}
+
+::view-transition-old(.tab-highlight),
+::view-transition-new(.tab-highlight) {
+  height: 100%;
+}
+::view-transition-group(.tab-text) {
+	z-index: 1;
+}
+
+::view-transition-old(.expand-accordion),
+::view-transition-new(.expand-accordion) {
+  width: auto;
+}
+::view-transition-group(.expand-accordion) {
+  overflow: clip;
+}
+
+/**
+ * For some reason, the original Monaco editor is still visible to the
+ * left of the DiffEditor. This is a workaround for better visual clarity.
+ */
+.monaco-diff-editor .editor.original{
+  visibility: hidden !important;
+}

compiler/packages/babel-plugin-react-compiler/src/HIR/CollectHoistablePropertyLoads.ts

@@ -454,6 +454,32 @@ function collectNonNullsInBlocks(
             assumedNonNullObjects.add(entry);
           }
         }
+      } else if (
+        fn.env.config.enablePreserveExistingMemoizationGuarantees &&
+        instr.value.kind === 'StartMemoize' &&
+        instr.value.deps != null
+      ) {
+        for (const dep of instr.value.deps) {
+          if (dep.root.kind === 'NamedLocal') {
+            if (
+              !isImmutableAtInstr(dep.root.value.identifier, instr.id, context)
+            ) {
+              continue;
+            }
+            for (let i = 0; i < dep.path.length; i++) {
+              const pathEntry = dep.path[i]!;
+              if (pathEntry.optional) {
+                break;
+              }
+              const depNode = context.registry.getOrCreateProperty({
+                identifier: dep.root.value.identifier,
+                path: dep.path.slice(0, i),
+                reactive: dep.root.value.reactive,
+              });
+              assumedNonNullObjects.add(depNode);
+            }
+          }
+        }
       }
     }
 

compiler/packages/babel-plugin-react-compiler/src/HIR/Environment.ts

@@ -210,7 +210,7 @@ export const EnvironmentConfigSchema = z.object({
    * that if a useEffect or useCallback references a function value, that function value will be
    * considered frozen, and in turn all of its referenced variables will be considered frozen as well.
    */
-  enablePreserveExistingMemoizationGuarantees: z.boolean().default(false),
+  enablePreserveExistingMemoizationGuarantees: z.boolean().default(true),
 
   /**
    * Validates that all useMemo/useCallback values are also memoized by Forget. This mode can be

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/allocating-primitive-as-dep.expect.md

@@ -2,6 +2,7 @@
 ## Input
 
 ```javascript
+// @enablePreserveExistingMemoizationGuarantees:false
 // bar(props.b) is an allocating expression that produces a primitive, which means
 // that Forget should memoize it.
 // Correctness:
@@ -16,7 +17,8 @@ function AllocatingPrimitiveAsDep(props) {
 ## Code
 
 ```javascript
-import { c as _c } from "react/compiler-runtime"; // bar(props.b) is an allocating expression that produces a primitive, which means
+import { c as _c } from "react/compiler-runtime"; // @enablePreserveExistingMemoizationGuarantees:false
+// bar(props.b) is an allocating expression that produces a primitive, which means
 // that Forget should memoize it.
 // Correctness:
 //   - y depends on either bar(props.b) or bar(props.b) + 1

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/allocating-primitive-as-dep.js

@@ -1,3 +1,4 @@
+// @enablePreserveExistingMemoizationGuarantees:false
 // bar(props.b) is an allocating expression that produces a primitive, which means
 // that Forget should memoize it.
 // Correctness:

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/allow-modify-global-in-callback-jsx.expect.md

@@ -2,6 +2,7 @@
 ## Input
 
 ```javascript
+// @enablePreserveExistingMemoizationGuarantees:false
 import {useMemo} from 'react';
 
 const someGlobal = {value: 0};
@@ -32,7 +33,7 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { c as _c } from "react/compiler-runtime";
+import { c as _c } from "react/compiler-runtime"; // @enablePreserveExistingMemoizationGuarantees:false
 import { useMemo } from "react";
 
 const someGlobal = { value: 0 };

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/allow-modify-global-in-callback-jsx.js

@@ -1,3 +1,4 @@
+// @enablePreserveExistingMemoizationGuarantees:false
 import {useMemo} from 'react';
 
 const someGlobal = {value: 0};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/computed-load-primitive-as-dependency.expect.md

@@ -2,6 +2,7 @@
 ## Input
 
 ```javascript
+// @enablePreserveExistingMemoizationGuarantees:false
 function Component(props) {
   let a = foo();
   // freeze `a` so we know the next line cannot mutate it
@@ -17,7 +18,7 @@ function Component(props) {
 ## Code
 
 ```javascript
-import { c as _c } from "react/compiler-runtime";
+import { c as _c } from "react/compiler-runtime"; // @enablePreserveExistingMemoizationGuarantees:false
 function Component(props) {
   const $ = _c(2);
   const a = foo();

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/computed-load-primitive-as-dependency.js

@@ -1,3 +1,4 @@
+// @enablePreserveExistingMemoizationGuarantees:false
 function Component(props) {
   let a = foo();
   // freeze `a` so we know the next line cannot mutate it

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/constant-propagation-template-literal.expect.md

@@ -2,6 +2,7 @@
 ## Input
 
 ```javascript
+// @enablePreserveExistingMemoizationGuarantees:false
 import {Stringify, identity} from 'shared-runtime';
 
 function foo() {
@@ -64,7 +65,7 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { c as _c } from "react/compiler-runtime";
+import { c as _c } from "react/compiler-runtime"; // @enablePreserveExistingMemoizationGuarantees:false
 import { Stringify, identity } from "shared-runtime";
 
 function foo() {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/constant-propagation-template-literal.js

@@ -1,3 +1,4 @@
+// @enablePreserveExistingMemoizationGuarantees:false
 import {Stringify, identity} from 'shared-runtime';
 
 function foo() {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/context-variable-as-jsx-element-tag.expect.md

@@ -2,6 +2,7 @@
 ## Input
 
 ```javascript
+// @enablePreserveExistingMemoizationGuarantees:false
 import {useMemo} from 'react';
 import {Stringify} from 'shared-runtime';
 
@@ -25,7 +26,7 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { c as _c } from "react/compiler-runtime";
+import { c as _c } from "react/compiler-runtime"; // @enablePreserveExistingMemoizationGuarantees:false
 import { useMemo } from "react";
 import { Stringify } from "shared-runtime";
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/context-variable-as-jsx-element-tag.js

@@ -1,3 +1,4 @@
+// @enablePreserveExistingMemoizationGuarantees:false
 import {useMemo} from 'react';
 import {Stringify} from 'shared-runtime';
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/destructure-direct-reassignment.expect.md

@@ -2,6 +2,7 @@
 ## Input
 
 ```javascript
+// @enablePreserveExistingMemoizationGuarantees:false
 function foo(props) {
   let x, y;
   ({x, y} = {x: props.a, y: props.b});
@@ -21,6 +22,7 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
+// @enablePreserveExistingMemoizationGuarantees:false
 function foo(props) {
   let x;
   let y;

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/destructure-direct-reassignment.js

@@ -1,3 +1,4 @@
+// @enablePreserveExistingMemoizationGuarantees:false
 function foo(props) {
   let x, y;
   ({x, y} = {x: props.a, y: props.b});

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-uncalled-function-capturing-mutable-values-memoizes-with-captures-values.expect.md

@@ -2,7 +2,7 @@
 ## Input
 
 ```javascript
-// @flow @enableNewMutationAliasingModel
+// @flow @enableNewMutationAliasingModel @enablePreserveExistingMemoizationGuarantees:false
 /**
  * This hook returns a function that when called with an input object,
  * will return the result of mapping that input with the supplied map

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-uncalled-function-capturing-mutable-values-memoizes-with-captures-values.js

@@ -1,4 +1,4 @@
-// @flow @enableNewMutationAliasingModel
+// @flow @enableNewMutationAliasingModel @enablePreserveExistingMemoizationGuarantees:false
 /**
  * This hook returns a function that when called with an input object,
  * will return the result of mapping that input with the supplied map

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.repro-preserve-memoization-inner-destructured-value-mistaken-as-dependency-later-mutation.expect.md

@@ -2,7 +2,7 @@
 ## Input
 
 ```javascript
-// @validatePreserveExistingMemoizationGuarantees
+// @validatePreserveExistingMemoizationGuarantees @enablePreserveExistingMemoizationGuarantees:false
 
 /**
  * Repro from https://github.com/facebook/react/issues/34262

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.repro-preserve-memoization-inner-destructured-value-mistaken-as-dependency-later-mutation.js

@@ -1,4 +1,4 @@
-// @validatePreserveExistingMemoizationGuarantees
+// @validatePreserveExistingMemoizationGuarantees @enablePreserveExistingMemoizationGuarantees:false
 
 /**
  * Repro from https://github.com/facebook/react/issues/34262

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.repro-preserve-memoization-inner-destructured-value-mistaken-as-dependency-mutated-dep.expect.md

@@ -2,7 +2,7 @@
 ## Input
 
 ```javascript
-// @validatePreserveExistingMemoizationGuarantees
+// @validatePreserveExistingMemoizationGuarantees @enablePreserveExistingMemoizationGuarantees:false
 
 import {identity, Stringify, useHook} from 'shared-runtime';
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.repro-preserve-memoization-inner-destructured-value-mistaken-as-dependency-mutated-dep.js

@@ -1,4 +1,4 @@
-// @validatePreserveExistingMemoizationGuarantees
+// @validatePreserveExistingMemoizationGuarantees @enablePreserveExistingMemoizationGuarantees:false
 
 import {identity, Stringify, useHook} from 'shared-runtime';
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.todo-preserve-memo-deps-mixed-optional-nonoptional-property-chain.expect.md

@@ -0,0 +1,91 @@
+
+## Input
+
+```javascript
+// @enablePreserveExistingMemoizationGuarantees @validatePreserveExistingMemoizationGuarantees @enableOptionalDependencies @enableTreatFunctionDepsAsConditional:false
+
+import {useMemo} from 'react';
+import {identity, ValidateMemoization} from 'shared-runtime';
+
+function Component({x}) {
+  const object = useMemo(() => {
+    return identity({
+      callback: () => {
+        // This is a bug in our dependency inference: we stop capturing dependencies
+        // after x.a.b?.c. But what this dependency is telling us is that if `x.a.b`
+        // was non-nullish, then we can access `.c.d?.e`. Thus we should take the
+        // full property chain, exactly as-is with optionals/non-optionals, as a
+        // dependency
+        return identity(x.a.b?.c.d?.e);
+      },
+    });
+  }, [x.a.b?.c.d?.e]);
+  const result = useMemo(() => {
+    return [object.callback()];
+  }, [object]);
+  return <Inner x={x} result={result} />;
+}
+
+function Inner({x, result}) {
+  'use no memo';
+  return <ValidateMemoization inputs={[x.y.z]} output={result} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{x: {y: {z: 42}}}],
+  sequentialRenders: [
+    {x: {y: {z: 42}}},
+    {x: {y: {z: 42}}},
+    {x: {y: {z: 3.14}}},
+    {x: {y: {z: 42}}},
+    {x: {y: {z: 3.14}}},
+    {x: {y: {z: 42}}},
+  ],
+};
+
+```
+
+
+## Error
+
+```
+Found 1 error:
+
+Compilation Skipped: Existing memoization could not be preserved
+
+React Compiler has skipped optimizing this component because the existing manual memoization could not be preserved. The inferred dependencies did not match the manually specified dependencies, which could cause the value to change more or less frequently than expected. The inferred dependency was `x.a.b?.c`, but the source dependencies were [x.a.b?.c.d?.e]. Inferred less specific property than source.
+
+error.todo-preserve-memo-deps-mixed-optional-nonoptional-property-chain.ts:7:25
+   5 |
+   6 | function Component({x}) {
+>  7 |   const object = useMemo(() => {
+     |                          ^^^^^^^
+>  8 |     return identity({
+     | ^^^^^^^^^^^^^^^^^^^^^
+>  9 |       callback: () => {
+     | ^^^^^^^^^^^^^^^^^^^^^
+> 10 |         // This is a bug in our dependency inference: we stop capturing dependencies
+     | ^^^^^^^^^^^^^^^^^^^^^
+> 11 |         // after x.a.b?.c. But what this dependency is telling us is that if `x.a.b`
+     | ^^^^^^^^^^^^^^^^^^^^^
+> 12 |         // was non-nullish, then we can access `.c.d?.e`. Thus we should take the
+     | ^^^^^^^^^^^^^^^^^^^^^
+> 13 |         // full property chain, exactly as-is with optionals/non-optionals, as a
+     | ^^^^^^^^^^^^^^^^^^^^^
+> 14 |         // dependency
+     | ^^^^^^^^^^^^^^^^^^^^^
+> 15 |         return identity(x.a.b?.c.d?.e);
+     | ^^^^^^^^^^^^^^^^^^^^^
+> 16 |       },
+     | ^^^^^^^^^^^^^^^^^^^^^
+> 17 |     });
+     | ^^^^^^^^^^^^^^^^^^^^^
+> 18 |   }, [x.a.b?.c.d?.e]);
+     | ^^^^ Could not preserve existing manual memoization
+  19 |   const result = useMemo(() => {
+  20 |     return [object.callback()];
+  21 |   }, [object]);
+```
+          
+      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.todo-preserve-memo-deps-mixed-optional-nonoptional-property-chain.js

@@ -0,0 +1,41 @@
+// @enablePreserveExistingMemoizationGuarantees @validatePreserveExistingMemoizationGuarantees @enableOptionalDependencies @enableTreatFunctionDepsAsConditional:false
+
+import {useMemo} from 'react';
+import {identity, ValidateMemoization} from 'shared-runtime';
+
+function Component({x}) {
+  const object = useMemo(() => {
+    return identity({
+      callback: () => {
+        // This is a bug in our dependency inference: we stop capturing dependencies
+        // after x.a.b?.c. But what this dependency is telling us is that if `x.a.b`
+        // was non-nullish, then we can access `.c.d?.e`. Thus we should take the
+        // full property chain, exactly as-is with optionals/non-optionals, as a
+        // dependency
+        return identity(x.a.b?.c.d?.e);
+      },
+    });
+  }, [x.a.b?.c.d?.e]);
+  const result = useMemo(() => {
+    return [object.callback()];
+  }, [object]);
+  return <Inner x={x} result={result} />;
+}
+
+function Inner({x, result}) {
+  'use no memo';
+  return <ValidateMemoization inputs={[x.y.z]} output={result} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{x: {y: {z: 42}}}],
+  sequentialRenders: [
+    {x: {y: {z: 42}}},
+    {x: {y: {z: 42}}},
+    {x: {y: {z: 3.14}}},
+    {x: {y: {z: 42}}},
+    {x: {y: {z: 3.14}}},
+    {x: {y: {z: 42}}},
+  ],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.todo-repro-missed-memoization-from-capture-in-invoked-function-inferred-as-mutation.expect.md

@@ -2,7 +2,7 @@
 ## Input
 
 ```javascript
-// @flow @validatePreserveExistingMemoizationGuarantees
+// @flow @validatePreserveExistingMemoizationGuarantees @enablePreserveExistingMemoizationGuarantees:false
 import {useMemo} from 'react';
 import {logValue, useFragment, useHook, typedLog} from 'shared-runtime';
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.todo-repro-missed-memoization-from-capture-in-invoked-function-inferred-as-mutation.js

@@ -1,4 +1,4 @@
-// @flow @validatePreserveExistingMemoizationGuarantees
+// @flow @validatePreserveExistingMemoizationGuarantees @enablePreserveExistingMemoizationGuarantees:false
 import {useMemo} from 'react';
 import {logValue, useFragment, useHook, typedLog} from 'shared-runtime';
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.todo-repro-missed-memoization-from-inferred-mutation-in-logger.expect.md

@@ -2,7 +2,7 @@
 ## Input
 
 ```javascript
-// @flow @validatePreserveExistingMemoizationGuarantees
+// @flow @validatePreserveExistingMemoizationGuarantees @enablePreserveExistingMemoizationGuarantees:false
 import {useFragment} from 'react-relay';
 import LogEvent from 'LogEvent';
 import {useCallback, useMemo} from 'react';

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.todo-repro-missed-memoization-from-inferred-mutation-in-logger.js

@@ -1,4 +1,4 @@
-// @flow @validatePreserveExistingMemoizationGuarantees
+// @flow @validatePreserveExistingMemoizationGuarantees @enablePreserveExistingMemoizationGuarantees:false
 import {useFragment} from 'react-relay';
 import LogEvent from 'LogEvent';
 import {useCallback, useMemo} from 'react';

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.todo-repro-unmemoized-callback-captured-in-context-variable.expect.md

@@ -2,7 +2,7 @@
 ## Input
 
 ```javascript
-// @validatePreserveExistingMemoizationGuarantees
+// @validatePreserveExistingMemoizationGuarantees @enablePreserveExistingMemoizationGuarantees:false
 import {useMemo} from 'react';
 import {ValidateMemoization, useHook} from 'shared-runtime';
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.todo-repro-unmemoized-callback-captured-in-context-variable.tsx

@@ -1,4 +1,4 @@
-// @validatePreserveExistingMemoizationGuarantees
+// @validatePreserveExistingMemoizationGuarantees @enablePreserveExistingMemoizationGuarantees:false
 import {useMemo} from 'react';
 import {ValidateMemoization, useHook} from 'shared-runtime';
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.validate-object-entries-mutation.expect.md

@@ -2,7 +2,7 @@
 ## Input
 
 ```javascript
-// @validatePreserveExistingMemoizationGuarantees
+// @validatePreserveExistingMemoizationGuarantees @enablePreserveExistingMemoizationGuarantees:false
 import {makeObject_Primitives, Stringify} from 'shared-runtime';
 
 function Component(props) {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.validate-object-entries-mutation.js

@@ -1,4 +1,4 @@
-// @validatePreserveExistingMemoizationGuarantees
+// @validatePreserveExistingMemoizationGuarantees @enablePreserveExistingMemoizationGuarantees:false
 import {makeObject_Primitives, Stringify} from 'shared-runtime';
 
 function Component(props) {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.validate-object-values-mutation.expect.md

@@ -2,7 +2,7 @@
 ## Input
 
 ```javascript
-// @validatePreserveExistingMemoizationGuarantees
+// @validatePreserveExistingMemoizationGuarantees @enablePreserveExistingMemoizationGuarantees:false
 import {makeObject_Primitives, Stringify} from 'shared-runtime';
 
 function Component(props) {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.validate-object-values-mutation.js

@@ -1,4 +1,4 @@
-// @validatePreserveExistingMemoizationGuarantees
+// @validatePreserveExistingMemoizationGuarantees @enablePreserveExistingMemoizationGuarantees:false
 import {makeObject_Primitives, Stringify} from 'shared-runtime';
 
 function Component(props) {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/existing-variables-with-c-name.expect.md

@@ -2,6 +2,7 @@
 ## Input
 
 ```javascript
+// @enablePreserveExistingMemoizationGuarantees:false
 import {useMemo, useState} from 'react';
 import {ValidateMemoization} from 'shared-runtime';
 
@@ -28,7 +29,7 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { c as _c2 } from "react/compiler-runtime";
+import { c as _c2 } from "react/compiler-runtime"; // @enablePreserveExistingMemoizationGuarantees:false
 import { useMemo, useState } from "react";
 import { ValidateMemoization } from "shared-runtime";
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/existing-variables-with-c-name.js

@@ -1,3 +1,4 @@
+// @enablePreserveExistingMemoizationGuarantees:false
 import {useMemo, useState} from 'react';
 import {ValidateMemoization} from 'shared-runtime';
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/fbt/bug-fbt-plural-multiple-function-calls.expect.md

@@ -2,6 +2,7 @@
 ## Input
 
 ```javascript
+// @enablePreserveExistingMemoizationGuarantees:false
 import fbt from 'fbt';
 
 /**
@@ -35,7 +36,7 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { c as _c } from "react/compiler-runtime";
+import { c as _c } from "react/compiler-runtime"; // @enablePreserveExistingMemoizationGuarantees:false
 import fbt from "fbt";
 
 /**

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/fbt/bug-fbt-plural-multiple-function-calls.ts

@@ -1,3 +1,4 @@
+// @enablePreserveExistingMemoizationGuarantees:false
 import fbt from 'fbt';
 
 /**

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/for-in-statement-type-inference.expect.md

@@ -2,6 +2,7 @@
 ## Input
 
 ```javascript
+// @enablePreserveExistingMemoizationGuarantees:false
 const {identity, mutate} = require('shared-runtime');
 
 function Component(props) {
@@ -24,6 +25,7 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
+// @enablePreserveExistingMemoizationGuarantees:false
 const { identity, mutate } = require("shared-runtime");
 
 function Component(props) {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/for-in-statement-type-inference.js

@@ -1,3 +1,4 @@
+// @enablePreserveExistingMemoizationGuarantees:false
 const {identity, mutate} = require('shared-runtime');
 
 function Component(props) {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/hooks-with-prefix.expect.md

@@ -2,7 +2,7 @@
 ## Input
 
 ```javascript
-// @hookPattern:".*\b(use[^$]+)$"
+// @hookPattern:".*\b(use[^$]+)$" @enablePreserveExistingMemoizationGuarantees:false
 
 import * as React from 'react';
 import {makeArray, useHook} from 'shared-runtime';
@@ -36,7 +36,7 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { c as _c } from "react/compiler-runtime"; // @hookPattern:".*\b(use[^$]+)$"
+import { c as _c } from "react/compiler-runtime"; // @hookPattern:".*\b(use[^$]+)$" @enablePreserveExistingMemoizationGuarantees:false
 
 import * as React from "react";
 import { makeArray, useHook } from "shared-runtime";

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/hooks-with-prefix.js

@@ -1,4 +1,4 @@
-// @hookPattern:".*\b(use[^$]+)$"
+// @hookPattern:".*\b(use[^$]+)$" @enablePreserveExistingMemoizationGuarantees:false
 
 import * as React from 'react';
 import {makeArray, useHook} from 'shared-runtime';

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/infer-computed-delete.expect.md

@@ -2,7 +2,7 @@
 ## Input
 
 ```javascript
-// @debug
+// @debug @enablePreserveExistingMemoizationGuarantees:false
 function Component(props) {
   const x = makeObject();
   const y = delete x[props.value];
@@ -14,7 +14,7 @@ function Component(props) {
 ## Code
 
 ```javascript
-// @debug
+// @debug @enablePreserveExistingMemoizationGuarantees:false
 function Component(props) {
   const x = makeObject();
   const y = delete x[props.value];

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/infer-computed-delete.js

@@ -1,4 +1,4 @@
-// @debug
+// @debug @enablePreserveExistingMemoizationGuarantees:false
 function Component(props) {
   const x = makeObject();
   const y = delete x[props.value];

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/infer-property-delete.expect.md

@@ -2,6 +2,7 @@
 ## Input
 
 ```javascript
+// @enablePreserveExistingMemoizationGuarantees:false
 function Component(props) {
   const x = makeObject();
   const y = delete x.value;
@@ -13,6 +14,7 @@ function Component(props) {
 ## Code
 
 ```javascript
+// @enablePreserveExistingMemoizationGuarantees:false
 function Component(props) {
   const x = makeObject();
   const y = delete x.value;

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/infer-property-delete.js

@@ -1,3 +1,4 @@
+// @enablePreserveExistingMemoizationGuarantees:false
 function Component(props) {
   const x = makeObject();
   const y = delete x.value;

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/error.invalid-useCallback-captures-reassigned-context.expect.md

@@ -2,7 +2,7 @@
 ## Input
 
 ```javascript
-// @validatePreserveExistingMemoizationGuarantees @enableNewMutationAliasingModel
+// @validatePreserveExistingMemoizationGuarantees @enableNewMutationAliasingModel @enablePreserveExistingMemoizationGuarantees:false
 import {useCallback} from 'react';
 import {makeArray} from 'shared-runtime';
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/error.invalid-useCallback-captures-reassigned-context.js

@@ -1,4 +1,4 @@
-// @validatePreserveExistingMemoizationGuarantees @enableNewMutationAliasingModel
+// @validatePreserveExistingMemoizationGuarantees @enableNewMutationAliasingModel @enablePreserveExistingMemoizationGuarantees:false
 import {useCallback} from 'react';
 import {makeArray} from 'shared-runtime';
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/mutate-through-identity-function-expression.expect.md

@@ -2,6 +2,7 @@
 ## Input
 
 ```javascript
+// @enablePreserveExistingMemoizationGuarantees:false
 import {useMemo} from 'react';
 import {identity, ValidateMemoization} from 'shared-runtime';
 
@@ -32,7 +33,7 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { c as _c } from "react/compiler-runtime";
+import { c as _c } from "react/compiler-runtime"; // @enablePreserveExistingMemoizationGuarantees:false
 import { useMemo } from "react";
 import { identity, ValidateMemoization } from "shared-runtime";
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/mutate-through-identity-function-expression.js

@@ -1,3 +1,4 @@
+// @enablePreserveExistingMemoizationGuarantees:false
 import {useMemo} from 'react';
 import {identity, ValidateMemoization} from 'shared-runtime';
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/mutate-through-identity.expect.md

@@ -2,6 +2,7 @@
 ## Input
 
 ```javascript
+// @enablePreserveExistingMemoizationGuarantees:false
 import {useMemo} from 'react';
 import {identity, ValidateMemoization} from 'shared-runtime';
 
@@ -29,7 +30,7 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { c as _c } from "react/compiler-runtime";
+import { c as _c } from "react/compiler-runtime"; // @enablePreserveExistingMemoizationGuarantees:false
 import { useMemo } from "react";
 import { identity, ValidateMemoization } from "shared-runtime";
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/mutate-through-identity.js

@@ -1,3 +1,4 @@
+// @enablePreserveExistingMemoizationGuarantees:false
 import {useMemo} from 'react';
 import {identity, ValidateMemoization} from 'shared-runtime';
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/todo-control-flow-sensitive-mutation.expect.md

@@ -2,6 +2,7 @@
 ## Input
 
 ```javascript
+// @enablePreserveExistingMemoizationGuarantees:false
 import {useMemo} from 'react';
 import {
   mutate,
@@ -49,7 +50,7 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { c as _c } from "react/compiler-runtime";
+import { c as _c } from "react/compiler-runtime"; // @enablePreserveExistingMemoizationGuarantees:false
 import { useMemo } from "react";
 import {
   mutate,

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/todo-control-flow-sensitive-mutation.tsx

@@ -1,3 +1,4 @@
+// @enablePreserveExistingMemoizationGuarantees:false
 import {useMemo} from 'react';
 import {
   mutate,

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/todo-transitivity-createfrom-capture-lambda.expect.md

@@ -2,6 +2,7 @@
 ## Input
 
 ```javascript
+// @enablePreserveExistingMemoizationGuarantees:false
 import {useMemo} from 'react';
 import {
   typedCapture,
@@ -41,7 +42,7 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { c as _c } from "react/compiler-runtime";
+import { c as _c } from "react/compiler-runtime"; // @enablePreserveExistingMemoizationGuarantees:false
 import { useMemo } from "react";
 import {
   typedCapture,

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/todo-transitivity-createfrom-capture-lambda.tsx

@@ -1,3 +1,4 @@
+// @enablePreserveExistingMemoizationGuarantees:false
 import {useMemo} from 'react';
 import {
   typedCapture,

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/transitivity-add-captured-array-to-itself.expect.md

@@ -2,6 +2,7 @@
 ## Input
 
 ```javascript
+// @enablePreserveExistingMemoizationGuarantees:false
 import {useMemo} from 'react';
 import {
   typedCapture,
@@ -42,7 +43,7 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { c as _c } from "react/compiler-runtime";
+import { c as _c } from "react/compiler-runtime"; // @enablePreserveExistingMemoizationGuarantees:false
 import { useMemo } from "react";
 import {
   typedCapture,

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/transitivity-add-captured-array-to-itself.tsx

@@ -1,3 +1,4 @@
+// @enablePreserveExistingMemoizationGuarantees:false
 import {useMemo} from 'react';
 import {
   typedCapture,

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/transitivity-capture-createfrom-lambda.expect.md

@@ -2,6 +2,7 @@
 ## Input
 
 ```javascript
+// @enablePreserveExistingMemoizationGuarantees:false
 import {useMemo} from 'react';
 import {
   typedCapture,
@@ -40,7 +41,7 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { c as _c } from "react/compiler-runtime";
+import { c as _c } from "react/compiler-runtime"; // @enablePreserveExistingMemoizationGuarantees:false
 import { useMemo } from "react";
 import {
   typedCapture,

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/transitivity-capture-createfrom-lambda.tsx

@@ -1,3 +1,4 @@
+// @enablePreserveExistingMemoizationGuarantees:false
 import {useMemo} from 'react';
 import {
   typedCapture,

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/transitivity-capture-createfrom.expect.md

@@ -2,6 +2,7 @@
 ## Input
 
 ```javascript
+// @enablePreserveExistingMemoizationGuarantees:false
 import {useMemo} from 'react';
 import {
   typedCapture,
@@ -36,7 +37,7 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { c as _c } from "react/compiler-runtime";
+import { c as _c } from "react/compiler-runtime"; // @enablePreserveExistingMemoizationGuarantees:false
 import { useMemo } from "react";
 import {
   typedCapture,

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/transitivity-capture-createfrom.tsx

@@ -1,3 +1,4 @@
+// @enablePreserveExistingMemoizationGuarantees:false
 import {useMemo} from 'react';
 import {
   typedCapture,

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/transitivity-phi-assign-or-capture.expect.md

@@ -2,6 +2,7 @@
 ## Input
 
 ```javascript
+// @enablePreserveExistingMemoizationGuarantees:false
 import {useMemo} from 'react';
 import {
   typedCapture,
@@ -40,7 +41,7 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { c as _c } from "react/compiler-runtime";
+import { c as _c } from "react/compiler-runtime"; // @enablePreserveExistingMemoizationGuarantees:false
 import { useMemo } from "react";
 import {
   typedCapture,

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/transitivity-phi-assign-or-capture.tsx

@@ -1,3 +1,4 @@
+// @enablePreserveExistingMemoizationGuarantees:false
 import {useMemo} from 'react';
 import {
   typedCapture,

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/useCallback-reordering-deplist-controlflow.expect.md

@@ -2,7 +2,7 @@
 ## Input
 
 ```javascript
-// @enableNewMutationAliasingModel
+// @enableNewMutationAliasingModel @enablePreserveExistingMemoizationGuarantees:false
 import {useCallback} from 'react';
 import {Stringify} from 'shared-runtime';
 
@@ -36,7 +36,7 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { c as _c } from "react/compiler-runtime"; // @enableNewMutationAliasingModel
+import { c as _c } from "react/compiler-runtime"; // @enableNewMutationAliasingModel @enablePreserveExistingMemoizationGuarantees:false
 import { useCallback } from "react";
 import { Stringify } from "shared-runtime";
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/useCallback-reordering-deplist-controlflow.tsx

@@ -1,4 +1,4 @@
-// @enableNewMutationAliasingModel
+// @enableNewMutationAliasingModel @enablePreserveExistingMemoizationGuarantees:false
 import {useCallback} from 'react';
 import {Stringify} from 'shared-runtime';
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/useCallback-reordering-depslist-assignment.expect.md

@@ -2,7 +2,7 @@
 ## Input
 
 ```javascript
-// @enableNewMutationAliasingModel
+// @enableNewMutationAliasingModel @enablePreserveExistingMemoizationGuarantees:false
 import {useCallback} from 'react';
 import {Stringify} from 'shared-runtime';
 
@@ -31,7 +31,7 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { c as _c } from "react/compiler-runtime"; // @enableNewMutationAliasingModel
+import { c as _c } from "react/compiler-runtime"; // @enableNewMutationAliasingModel @enablePreserveExistingMemoizationGuarantees:false
 import { useCallback } from "react";
 import { Stringify } from "shared-runtime";
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/useCallback-reordering-depslist-assignment.tsx

@@ -1,4 +1,4 @@
-// @enableNewMutationAliasingModel
+// @enableNewMutationAliasingModel @enablePreserveExistingMemoizationGuarantees:false
 import {useCallback} from 'react';
 import {Stringify} from 'shared-runtime';
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/useMemo-reordering-depslist-assignment.expect.md

@@ -2,7 +2,7 @@
 ## Input
 
 ```javascript
-// @enableNewMutationAliasingModel
+// @enableNewMutationAliasingModel @enablePreserveExistingMemoizationGuarantees:false
 import {useMemo} from 'react';
 
 function useFoo(arr1, arr2) {
@@ -27,7 +27,7 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { c as _c } from "react/compiler-runtime"; // @enableNewMutationAliasingModel
+import { c as _c } from "react/compiler-runtime"; // @enableNewMutationAliasingModel @enablePreserveExistingMemoizationGuarantees:false
 import { useMemo } from "react";
 
 function useFoo(arr1, arr2) {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/useMemo-reordering-depslist-assignment.ts

@@ -1,4 +1,4 @@
-// @enableNewMutationAliasingModel
+// @enableNewMutationAliasingModel @enablePreserveExistingMemoizationGuarantees:false
 import {useMemo} from 'react';
 
 function useFoo(arr1, arr2) {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/preserve-memo-deps-conditional-property-chain-less-precise-deps.expect.md

@@ -0,0 +1,122 @@
+
+## Input
+
+```javascript
+// @enablePreserveExistingMemoizationGuarantees @validatePreserveExistingMemoizationGuarantees @enableOptionalDependencies @enableTreatFunctionDepsAsConditional:false
+
+import {useMemo} from 'react';
+import {identity, ValidateMemoization} from 'shared-runtime';
+
+function Component({x}) {
+  const object = useMemo(() => {
+    return identity({
+      callback: () => {
+        return identity(x.y.z); // accesses more levels of properties than the manual memo
+      },
+    });
+    // x.y as a manual dep only tells us that x is non-nullable, not that x.y is non-nullable
+    // we can only take a dep on x.y, not x.y.z
+  }, [x.y]);
+  const result = useMemo(() => {
+    return [object.callback()];
+  }, [object]);
+  return <ValidateMemoization inputs={[x.y]} output={result} />;
+}
+
+const input1 = {x: {y: {z: 42}}};
+const input1b = {x: {y: {z: 42}}};
+const input2 = {x: {y: {z: 3.14}}};
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [input1],
+  sequentialRenders: [
+    input1,
+    input1,
+    input1b, // should reset even though .z didn't change
+    input1,
+    input2,
+  ],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @enablePreserveExistingMemoizationGuarantees @validatePreserveExistingMemoizationGuarantees @enableOptionalDependencies @enableTreatFunctionDepsAsConditional:false
+
+import { useMemo } from "react";
+import { identity, ValidateMemoization } from "shared-runtime";
+
+function Component(t0) {
+  const $ = _c(11);
+  const { x } = t0;
+  let t1;
+  if ($[0] !== x.y) {
+    t1 = identity({ callback: () => identity(x.y.z) });
+    $[0] = x.y;
+    $[1] = t1;
+  } else {
+    t1 = $[1];
+  }
+  const object = t1;
+  let t2;
+  if ($[2] !== object) {
+    t2 = object.callback();
+    $[2] = object;
+    $[3] = t2;
+  } else {
+    t2 = $[3];
+  }
+  let t3;
+  if ($[4] !== t2) {
+    t3 = [t2];
+    $[4] = t2;
+    $[5] = t3;
+  } else {
+    t3 = $[5];
+  }
+  const result = t3;
+  let t4;
+  if ($[6] !== x.y) {
+    t4 = [x.y];
+    $[6] = x.y;
+    $[7] = t4;
+  } else {
+    t4 = $[7];
+  }
+  let t5;
+  if ($[8] !== result || $[9] !== t4) {
+    t5 = <ValidateMemoization inputs={t4} output={result} />;
+    $[8] = result;
+    $[9] = t4;
+    $[10] = t5;
+  } else {
+    t5 = $[10];
+  }
+  return t5;
+}
+
+const input1 = { x: { y: { z: 42 } } };
+const input1b = { x: { y: { z: 42 } } };
+const input2 = { x: { y: { z: 3.14 } } };
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [input1],
+  sequentialRenders: [
+    input1,
+    input1,
+    input1b, // should reset even though .z didn't change
+    input1,
+    input2,
+  ],
+};
+
+```
+      
+### Eval output
+(kind: ok) <div>{"inputs":[{"z":42}],"output":[42]}</div>
+<div>{"inputs":[{"z":42}],"output":[42]}</div>
+<div>{"inputs":[{"z":42}],"output":[42]}</div>
+<div>{"inputs":[{"z":42}],"output":[42]}</div>
+<div>{"inputs":[{"z":3.14}],"output":[3.14]}</div>

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/preserve-memo-deps-conditional-property-chain-less-precise-deps.js

@@ -0,0 +1,35 @@
+// @enablePreserveExistingMemoizationGuarantees @validatePreserveExistingMemoizationGuarantees @enableOptionalDependencies @enableTreatFunctionDepsAsConditional:false
+
+import {useMemo} from 'react';
+import {identity, ValidateMemoization} from 'shared-runtime';
+
+function Component({x}) {
+  const object = useMemo(() => {
+    return identity({
+      callback: () => {
+        return identity(x.y.z); // accesses more levels of properties than the manual memo
+      },
+    });
+    // x.y as a manual dep only tells us that x is non-nullable, not that x.y is non-nullable
+    // we can only take a dep on x.y, not x.y.z
+  }, [x.y]);
+  const result = useMemo(() => {
+    return [object.callback()];
+  }, [object]);
+  return <ValidateMemoization inputs={[x.y]} output={result} />;
+}
+
+const input1 = {x: {y: {z: 42}}};
+const input1b = {x: {y: {z: 42}}};
+const input2 = {x: {y: {z: 3.14}}};
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [input1],
+  sequentialRenders: [
+    input1,
+    input1,
+    input1b, // should reset even though .z didn't change
+    input1,
+    input2,
+  ],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/preserve-memo-deps-conditional-property-chain.expect.md

@@ -0,0 +1,117 @@
+
+## Input
+
+```javascript
+// @enablePreserveExistingMemoizationGuarantees @validatePreserveExistingMemoizationGuarantees @enableOptionalDependencies @enableTreatFunctionDepsAsConditional:false
+
+import {useMemo} from 'react';
+import {identity, ValidateMemoization} from 'shared-runtime';
+
+function Component({x}) {
+  const object = useMemo(() => {
+    return identity({
+      callback: () => {
+        return identity(x.y.z);
+      },
+    });
+  }, [x.y.z]);
+  const result = useMemo(() => {
+    return [object.callback()];
+  }, [object]);
+  return <ValidateMemoization inputs={[x.y.z]} output={result} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{x: {y: {z: 42}}}],
+  sequentialRenders: [
+    {x: {y: {z: 42}}},
+    {x: {y: {z: 42}}},
+    {x: {y: {z: 3.14}}},
+    {x: {y: {z: 42}}},
+    {x: {y: {z: 3.14}}},
+    {x: {y: {z: 42}}},
+  ],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @enablePreserveExistingMemoizationGuarantees @validatePreserveExistingMemoizationGuarantees @enableOptionalDependencies @enableTreatFunctionDepsAsConditional:false
+
+import { useMemo } from "react";
+import { identity, ValidateMemoization } from "shared-runtime";
+
+function Component(t0) {
+  const $ = _c(11);
+  const { x } = t0;
+  let t1;
+  if ($[0] !== x.y.z) {
+    t1 = identity({ callback: () => identity(x.y.z) });
+    $[0] = x.y.z;
+    $[1] = t1;
+  } else {
+    t1 = $[1];
+  }
+  const object = t1;
+  let t2;
+  if ($[2] !== object) {
+    t2 = object.callback();
+    $[2] = object;
+    $[3] = t2;
+  } else {
+    t2 = $[3];
+  }
+  let t3;
+  if ($[4] !== t2) {
+    t3 = [t2];
+    $[4] = t2;
+    $[5] = t3;
+  } else {
+    t3 = $[5];
+  }
+  const result = t3;
+  let t4;
+  if ($[6] !== x.y.z) {
+    t4 = [x.y.z];
+    $[6] = x.y.z;
+    $[7] = t4;
+  } else {
+    t4 = $[7];
+  }
+  let t5;
+  if ($[8] !== result || $[9] !== t4) {
+    t5 = <ValidateMemoization inputs={t4} output={result} />;
+    $[8] = result;
+    $[9] = t4;
+    $[10] = t5;
+  } else {
+    t5 = $[10];
+  }
+  return t5;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{ x: { y: { z: 42 } } }],
+  sequentialRenders: [
+    { x: { y: { z: 42 } } },
+    { x: { y: { z: 42 } } },
+    { x: { y: { z: 3.14 } } },
+    { x: { y: { z: 42 } } },
+    { x: { y: { z: 3.14 } } },
+    { x: { y: { z: 42 } } },
+  ],
+};
+
+```
+      
+### Eval output
+(kind: ok) <div>{"inputs":[42],"output":[42]}</div>
+<div>{"inputs":[42],"output":[42]}</div>
+<div>{"inputs":[3.14],"output":[3.14]}</div>
+<div>{"inputs":[42],"output":[42]}</div>
+<div>{"inputs":[3.14],"output":[3.14]}</div>
+<div>{"inputs":[42],"output":[42]}</div>

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/preserve-memo-deps-conditional-property-chain.js

@@ -0,0 +1,31 @@
+// @enablePreserveExistingMemoizationGuarantees @validatePreserveExistingMemoizationGuarantees @enableOptionalDependencies @enableTreatFunctionDepsAsConditional:false
+
+import {useMemo} from 'react';
+import {identity, ValidateMemoization} from 'shared-runtime';
+
+function Component({x}) {
+  const object = useMemo(() => {
+    return identity({
+      callback: () => {
+        return identity(x.y.z);
+      },
+    });
+  }, [x.y.z]);
+  const result = useMemo(() => {
+    return [object.callback()];
+  }, [object]);
+  return <ValidateMemoization inputs={[x.y.z]} output={result} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{x: {y: {z: 42}}}],
+  sequentialRenders: [
+    {x: {y: {z: 42}}},
+    {x: {y: {z: 42}}},
+    {x: {y: {z: 3.14}}},
+    {x: {y: {z: 42}}},
+    {x: {y: {z: 3.14}}},
+    {x: {y: {z: 42}}},
+  ],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/preserve-memo-deps-optional-property-chain.expect.md

@@ -0,0 +1,125 @@
+
+## Input
+
+```javascript
+// @enablePreserveExistingMemoizationGuarantees @validatePreserveExistingMemoizationGuarantees @enableOptionalDependencies @enableTreatFunctionDepsAsConditional:false
+
+import {useMemo} from 'react';
+import {identity, ValidateMemoization} from 'shared-runtime';
+
+function Component({x, y, z}) {
+  const object = useMemo(() => {
+    return identity({
+      callback: () => {
+        return identity(x?.y?.z, y.a?.b, z.a.b?.c);
+      },
+    });
+  }, [x?.y?.z, y.a?.b, z.a.b?.c]);
+  const result = useMemo(() => {
+    return [object.callback()];
+  }, [object]);
+  return <Inner x={x} result={result} />;
+}
+
+function Inner({x, result}) {
+  'use no memo';
+  return <ValidateMemoization inputs={[x.y.z]} output={result} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{x: {y: {z: 42}}}],
+  sequentialRenders: [
+    {x: {y: {z: 42}}},
+    {x: {y: {z: 42}}},
+    {x: {y: {z: 3.14}}},
+    {x: {y: {z: 42}}},
+    {x: {y: {z: 3.14}}},
+    {x: {y: {z: 42}}},
+  ],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @enablePreserveExistingMemoizationGuarantees @validatePreserveExistingMemoizationGuarantees @enableOptionalDependencies @enableTreatFunctionDepsAsConditional:false
+
+import { useMemo } from "react";
+import { identity, ValidateMemoization } from "shared-runtime";
+
+function Component(t0) {
+  const $ = _c(11);
+  const { x, y, z } = t0;
+
+  x?.y?.z;
+  y.a?.b;
+  z.a.b?.c;
+  let t1;
+  if ($[0] !== x?.y?.z || $[1] !== y.a?.b || $[2] !== z.a.b?.c) {
+    t1 = identity({ callback: () => identity(x?.y?.z, y.a?.b, z.a.b?.c) });
+    $[0] = x?.y?.z;
+    $[1] = y.a?.b;
+    $[2] = z.a.b?.c;
+    $[3] = t1;
+  } else {
+    t1 = $[3];
+  }
+  const object = t1;
+  let t2;
+  if ($[4] !== object) {
+    t2 = object.callback();
+    $[4] = object;
+    $[5] = t2;
+  } else {
+    t2 = $[5];
+  }
+  let t3;
+  if ($[6] !== t2) {
+    t3 = [t2];
+    $[6] = t2;
+    $[7] = t3;
+  } else {
+    t3 = $[7];
+  }
+  const result = t3;
+  let t4;
+  if ($[8] !== result || $[9] !== x) {
+    t4 = <Inner x={x} result={result} />;
+    $[8] = result;
+    $[9] = x;
+    $[10] = t4;
+  } else {
+    t4 = $[10];
+  }
+  return t4;
+}
+
+function Inner({ x, result }) {
+  "use no memo";
+  return <ValidateMemoization inputs={[x.y.z]} output={result} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{ x: { y: { z: 42 } } }],
+  sequentialRenders: [
+    { x: { y: { z: 42 } } },
+    { x: { y: { z: 42 } } },
+    { x: { y: { z: 3.14 } } },
+    { x: { y: { z: 42 } } },
+    { x: { y: { z: 3.14 } } },
+    { x: { y: { z: 42 } } },
+  ],
+};
+
+```
+      
+### Eval output
+(kind: ok) [[ (exception in render) TypeError: Cannot read properties of undefined (reading 'a') ]]
+[[ (exception in render) TypeError: Cannot read properties of undefined (reading 'a') ]]
+[[ (exception in render) TypeError: Cannot read properties of undefined (reading 'a') ]]
+[[ (exception in render) TypeError: Cannot read properties of undefined (reading 'a') ]]
+[[ (exception in render) TypeError: Cannot read properties of undefined (reading 'a') ]]
+[[ (exception in render) TypeError: Cannot read properties of undefined (reading 'a') ]]

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/preserve-memo-deps-optional-property-chain.js

@@ -0,0 +1,36 @@
+// @enablePreserveExistingMemoizationGuarantees @validatePreserveExistingMemoizationGuarantees @enableOptionalDependencies @enableTreatFunctionDepsAsConditional:false
+
+import {useMemo} from 'react';
+import {identity, ValidateMemoization} from 'shared-runtime';
+
+function Component({x, y, z}) {
+  const object = useMemo(() => {
+    return identity({
+      callback: () => {
+        return identity(x?.y?.z, y.a?.b, z.a.b?.c);
+      },
+    });
+  }, [x?.y?.z, y.a?.b, z.a.b?.c]);
+  const result = useMemo(() => {
+    return [object.callback()];
+  }, [object]);
+  return <Inner x={x} result={result} />;
+}
+
+function Inner({x, result}) {
+  'use no memo';
+  return <ValidateMemoization inputs={[x.y.z]} output={result} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{x: {y: {z: 42}}}],
+  sequentialRenders: [
+    {x: {y: {z: 42}}},
+    {x: {y: {z: 42}}},
+    {x: {y: {z: 3.14}}},
+    {x: {y: {z: 42}}},
+    {x: {y: {z: 3.14}}},
+    {x: {y: {z: 42}}},
+  ],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/preserve-memo-validation/error.false-positive-useMemo-infer-mutate-deps.expect.md

@@ -2,7 +2,7 @@
 ## Input
 
 ```javascript
-// @validatePreserveExistingMemoizationGuarantees
+// @validatePreserveExistingMemoizationGuarantees @enablePreserveExistingMemoizationGuarantees:false
 import {useMemo} from 'react';
 import {identity} from 'shared-runtime';
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/preserve-memo-validation/error.false-positive-useMemo-infer-mutate-deps.ts

@@ -1,4 +1,4 @@
-// @validatePreserveExistingMemoizationGuarantees
+// @validatePreserveExistingMemoizationGuarantees @enablePreserveExistingMemoizationGuarantees:false
 import {useMemo} from 'react';
 import {identity} from 'shared-runtime';
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/preserve-memo-validation/error.hoist-useCallback-conditional-access-own-scope.expect.md

@@ -2,7 +2,7 @@
 ## Input
 
 ```javascript
-// @validatePreserveExistingMemoizationGuarantees
+// @validatePreserveExistingMemoizationGuarantees @enablePreserveExistingMemoizationGuarantees:false
 import {useCallback} from 'react';
 
 function Component({propA, propB}) {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/preserve-memo-validation/error.hoist-useCallback-conditional-access-own-scope.ts

@@ -1,4 +1,4 @@
-// @validatePreserveExistingMemoizationGuarantees
+// @validatePreserveExistingMemoizationGuarantees @enablePreserveExistingMemoizationGuarantees:false
 import {useCallback} from 'react';
 
 function Component({propA, propB}) {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/preserve-memo-validation/error.hoist-useCallback-infer-conditional-value-block.expect.md

@@ -2,7 +2,7 @@
 ## Input
 
 ```javascript
-// @validatePreserveExistingMemoizationGuarantees
+// @validatePreserveExistingMemoizationGuarantees @enablePreserveExistingMemoizationGuarantees:false
 import {useCallback} from 'react';
 import {identity, mutate} from 'shared-runtime';
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/preserve-memo-validation/error.hoist-useCallback-infer-conditional-value-block.ts

@@ -1,4 +1,4 @@
-// @validatePreserveExistingMemoizationGuarantees
+// @validatePreserveExistingMemoizationGuarantees @enablePreserveExistingMemoizationGuarantees:false
 import {useCallback} from 'react';
 import {identity, mutate} from 'shared-runtime';
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/preserve-memo-validation/error.invalid-useCallback-captures-reassigned-context.expect.md

@@ -2,7 +2,7 @@
 ## Input
 
 ```javascript
-// @validatePreserveExistingMemoizationGuarantees
+// @validatePreserveExistingMemoizationGuarantees @enablePreserveExistingMemoizationGuarantees:false
 
 import {useCallback} from 'react';
 import {makeArray} from 'shared-runtime';

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/preserve-memo-validation/error.invalid-useCallback-captures-reassigned-context.ts

@@ -1,4 +1,4 @@
-// @validatePreserveExistingMemoizationGuarantees
+// @validatePreserveExistingMemoizationGuarantees @enablePreserveExistingMemoizationGuarantees:false
 
 import {useCallback} from 'react';
 import {makeArray} from 'shared-runtime';

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/preserve-memo-validation/error.useCallback-conditional-access-noAlloc.expect.md

@@ -2,7 +2,7 @@
 ## Input
 
 ```javascript
-// @validatePreserveExistingMemoizationGuarantees
+// @validatePreserveExistingMemoizationGuarantees @enablePreserveExistingMemoizationGuarantees:false
 import {useCallback} from 'react';
 
 function Component({propA, propB}) {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/preserve-memo-validation/error.useCallback-conditional-access-noAlloc.ts

@@ -1,4 +1,4 @@
-// @validatePreserveExistingMemoizationGuarantees
+// @validatePreserveExistingMemoizationGuarantees @enablePreserveExistingMemoizationGuarantees:false
 import {useCallback} from 'react';
 
 function Component({propA, propB}) {