From 6d510c328b6a25cca24fd626208a308894ae991e Mon Sep 17 00:00:00 2001
From: Sebastian Sebbie Silbermann <sebastian.silbermann@vercel.com>
Date: Mon, 13 Oct 2025 09:45:37 +0200
Subject: [PATCH 1/2] Current behavior for uEE in React.memo

---
 .../src/__tests__/useEffectEvent-test.js      | 39 +++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/packages/react-reconciler/src/__tests__/useEffectEvent-test.js b/packages/react-reconciler/src/__tests__/useEffectEvent-test.js
index 17b8d6d421f..edee01ef634 100644
--- a/packages/react-reconciler/src/__tests__/useEffectEvent-test.js
+++ b/packages/react-reconciler/src/__tests__/useEffectEvent-test.js
@@ -850,4 +850,43 @@ describe('useEffectEvent', () => {
     );
     assertLog(['Add to cart', 'url: /shop/2, numberOfItems: 1']);
   });
+
+  it('reads the latest context value in memo Components', async () => {
+    const MyContext = createContext('default');
+
+    let logContextValue;
+    const ContextReader = React.memo(function ContextReader() {
+      const value = useContext(MyContext);
+      Scheduler.log('ContextReader: ' + value);
+      const fireLogContextValue = useEffectEvent(() => {
+        Scheduler.log('ContextReader (Effect event): ' + value);
+      });
+      useEffect(() => {
+        logContextValue = fireLogContextValue;
+      }, []);
+      return null;
+    });
+
+    function App({value}) {
+      return (
+        <MyContext.Provider value={value}>
+          <ContextReader />
+        </MyContext.Provider>
+      );
+    }
+
+    const root = ReactNoop.createRoot();
+    await act(() => root.render(<App value="first" />));
+    assertLog(['ContextReader: first']);
+
+    logContextValue();
+
+    assertLog(['ContextReader (Effect event): first']);
+
+    await act(() => root.render(<App value="second" />));
+    assertLog(['ContextReader: second']);
+
+    logContextValue();
+    assertLog(['ContextReader (Effect event): first']);
+  });
 });

From 6bec011b407fe8a2d4babb363289ccce4bc8fcf3 Mon Sep 17 00:00:00 2001
From: Sebastian Sebbie Silbermann <sebastian.silbermann@vercel.com>
Date: Mon, 13 Oct 2025 09:59:25 +0200
Subject: [PATCH 2/2] [Fiber] Ensure Effect events read latest values in
 `forwardRef` and `memo()` Components

---
 .../src/ReactFiberCommitWork.js               |  8 ++--
 .../src/__tests__/useEffectEvent-test.js      | 39 +++++++++++++++++++
 2 files changed, 42 insertions(+), 5 deletions(-)

diff --git a/packages/react-reconciler/src/ReactFiberCommitWork.js b/packages/react-reconciler/src/ReactFiberCommitWork.js
index c98edc7a0bc..dbb4e7a7973 100644
--- a/packages/react-reconciler/src/ReactFiberCommitWork.js
+++ b/packages/react-reconciler/src/ReactFiberCommitWork.js
@@ -493,7 +493,9 @@ function commitBeforeMutationEffectsOnFiber(
   }
 
   switch (finishedWork.tag) {
-    case FunctionComponent: {
+    case FunctionComponent:
+    case ForwardRef:
+    case SimpleMemoComponent: {
       if (enableUseEffectEventHook) {
         if ((flags & Update) !== NoFlags) {
           const updateQueue: FunctionComponentUpdateQueue | null =
@@ -510,10 +512,6 @@ function commitBeforeMutationEffectsOnFiber(
       }
       break;
     }
-    case ForwardRef:
-    case SimpleMemoComponent: {
-      break;
-    }
     case ClassComponent: {
       if ((flags & Snapshot) !== NoFlags) {
         if (current !== null) {
diff --git a/packages/react-reconciler/src/__tests__/useEffectEvent-test.js b/packages/react-reconciler/src/__tests__/useEffectEvent-test.js
index edee01ef634..f263c9af269 100644
--- a/packages/react-reconciler/src/__tests__/useEffectEvent-test.js
+++ b/packages/react-reconciler/src/__tests__/useEffectEvent-test.js
@@ -887,6 +887,45 @@ describe('useEffectEvent', () => {
     assertLog(['ContextReader: second']);
 
     logContextValue();
+    assertLog(['ContextReader (Effect event): second']);
+  });
+
+  it('reads the latest context value in forwardRef Components', async () => {
+    const MyContext = createContext('default');
+
+    let logContextValue;
+    const ContextReader = React.forwardRef(function ContextReader(props, ref) {
+      const value = useContext(MyContext);
+      Scheduler.log('ContextReader: ' + value);
+      const fireLogContextValue = useEffectEvent(() => {
+        Scheduler.log('ContextReader (Effect event): ' + value);
+      });
+      useEffect(() => {
+        logContextValue = fireLogContextValue;
+      }, []);
+      return null;
+    });
+
+    function App({value}) {
+      return (
+        <MyContext.Provider value={value}>
+          <ContextReader />
+        </MyContext.Provider>
+      );
+    }
+
+    const root = ReactNoop.createRoot();
+    await act(() => root.render(<App value="first" />));
+    assertLog(['ContextReader: first']);
+
+    logContextValue();
+
     assertLog(['ContextReader (Effect event): first']);
+
+    await act(() => root.render(<App value="second" />));
+    assertLog(['ContextReader: second']);
+
+    logContextValue();
+    assertLog(['ContextReader (Effect event): second']);
   });
 });