From 90c6d1b218bbe07eeb757ce8777805a9b7f8e3c3 Mon Sep 17 00:00:00 2001
From: Joseph Savona <6425824+josephsavona@users.noreply.github.com>
Date: Wed, 4 Feb 2026 10:09:28 -0500
Subject: [PATCH 1/7] [compiler][snap] More minimization improvements (#35689)

* A few new minimization strategies, removing function params and
array/object pattern elements
* Ensure that we preserve the same set of errors based on not just
category+reason but also description.
---
 compiler/packages/snap/src/minimize.ts | 136 ++++++++++++++++++++++++-
 1 file changed, 133 insertions(+), 3 deletions(-)

diff --git a/compiler/packages/snap/src/minimize.ts b/compiler/packages/snap/src/minimize.ts
index 0cce5ce1bdee..c734c9306d98 100644
--- a/compiler/packages/snap/src/minimize.ts
+++ b/compiler/packages/snap/src/minimize.ts
@@ -18,7 +18,7 @@ type CompileSuccess = {kind: 'success'};
 type CompileParseError = {kind: 'parse_error'; message: string};
 type CompileErrors = {
   kind: 'errors';
-  errors: Array<{category: string; reason: string}>;
+  errors: Array<{category: string; reason: string; description: string | null}>;
 };
 type CompileResult = CompileSuccess | CompileParseError | CompileErrors;
 
@@ -70,7 +70,11 @@ function compileAndGetError(
     return {kind: 'success'};
   } catch (e: unknown) {
     const error = e as Error & {
-      details?: Array<{category: string; reason: string}>;
+      details?: Array<{
+        category: string;
+        reason: string;
+        description: string | null;
+      }>;
     };
     // Check if this is a CompilerError with details
     if (error.details && error.details.length > 0) {
@@ -79,6 +83,7 @@ function compileAndGetError(
         errors: error.details.map(detail => ({
           category: detail.category,
           reason: detail.reason,
+          description: detail.description,
         })),
       };
     }
@@ -89,6 +94,7 @@ function compileAndGetError(
         {
           category: error.name ?? 'Error',
           reason: error.message,
+          description: null,
         },
       ],
     };
@@ -108,7 +114,8 @@ function errorsMatch(a: CompileErrors, b: CompileResult): boolean {
   for (let i = 0; i < a.errors.length; i++) {
     if (
       a.errors[i].category !== b.errors[i].category ||
-      a.errors[i].reason !== b.errors[i].reason
+      a.errors[i].reason !== b.errors[i].reason ||
+      a.errors[i].description !== b.errors[i].description
     ) {
       return false;
     }
@@ -217,6 +224,45 @@ function* removeCallArguments(ast: t.File): Generator<t.File> {
   }
 }
 
+/**
+ * Generator that yields ASTs with function parameters removed one at a time
+ */
+function* removeFunctionParameters(ast: t.File): Generator<t.File> {
+  // Collect all functions with parameters
+  const funcSites: Array<{funcIndex: number; paramCount: number}> = [];
+  let funcIndex = 0;
+  t.traverseFast(ast, node => {
+    if (t.isFunction(node) && node.params.length > 0) {
+      funcSites.push({funcIndex, paramCount: node.params.length});
+      funcIndex++;
+    }
+  });
+
+  // For each function, try removing each parameter (from end to start)
+  for (const {funcIndex: targetFuncIdx, paramCount} of funcSites) {
+    for (let paramIdx = paramCount - 1; paramIdx >= 0; paramIdx--) {
+      const cloned = cloneAst(ast);
+      let idx = 0;
+      let modified = false;
+
+      t.traverseFast(cloned, node => {
+        if (modified) return;
+        if (t.isFunction(node) && node.params.length > 0) {
+          if (idx === targetFuncIdx && paramIdx < node.params.length) {
+            node.params.splice(paramIdx, 1);
+            modified = true;
+          }
+          idx++;
+        }
+      });
+
+      if (modified) {
+        yield cloned;
+      }
+    }
+  }
+}
+
 /**
  * Generator that simplifies call expressions by replacing them with their arguments.
  * For single argument: foo(x) -> x
@@ -1566,6 +1612,84 @@ function* removeObjectProperties(ast: t.File): Generator<t.File> {
   }
 }
 
+/**
+ * Generator that removes elements from array destructuring patterns one at a time
+ */
+function* removeArrayPatternElements(ast: t.File): Generator<t.File> {
+  // Collect all array patterns with elements
+  const patternSites: Array<{patternIndex: number; elementCount: number}> = [];
+  let patternIndex = 0;
+  t.traverseFast(ast, node => {
+    if (t.isArrayPattern(node) && node.elements.length > 0) {
+      patternSites.push({patternIndex, elementCount: node.elements.length});
+      patternIndex++;
+    }
+  });
+
+  // For each pattern, try removing each element (from end to start)
+  for (const {patternIndex: targetPatternIdx, elementCount} of patternSites) {
+    for (let elemIdx = elementCount - 1; elemIdx >= 0; elemIdx--) {
+      const cloned = cloneAst(ast);
+      let idx = 0;
+      let modified = false;
+
+      t.traverseFast(cloned, node => {
+        if (modified) return;
+        if (t.isArrayPattern(node) && node.elements.length > 0) {
+          if (idx === targetPatternIdx && elemIdx < node.elements.length) {
+            node.elements.splice(elemIdx, 1);
+            modified = true;
+          }
+          idx++;
+        }
+      });
+
+      if (modified) {
+        yield cloned;
+      }
+    }
+  }
+}
+
+/**
+ * Generator that removes properties from object destructuring patterns one at a time
+ */
+function* removeObjectPatternProperties(ast: t.File): Generator<t.File> {
+  // Collect all object patterns with properties
+  const patternSites: Array<{patternIndex: number; propCount: number}> = [];
+  let patternIndex = 0;
+  t.traverseFast(ast, node => {
+    if (t.isObjectPattern(node) && node.properties.length > 0) {
+      patternSites.push({patternIndex, propCount: node.properties.length});
+      patternIndex++;
+    }
+  });
+
+  // For each pattern, try removing each property (from end to start)
+  for (const {patternIndex: targetPatternIdx, propCount} of patternSites) {
+    for (let propIdx = propCount - 1; propIdx >= 0; propIdx--) {
+      const cloned = cloneAst(ast);
+      let idx = 0;
+      let modified = false;
+
+      t.traverseFast(cloned, node => {
+        if (modified) return;
+        if (t.isObjectPattern(node) && node.properties.length > 0) {
+          if (idx === targetPatternIdx && propIdx < node.properties.length) {
+            node.properties.splice(propIdx, 1);
+            modified = true;
+          }
+          idx++;
+        }
+      });
+
+      if (modified) {
+        yield cloned;
+      }
+    }
+  }
+}
+
 /**
  * Generator that simplifies assignment expressions (a = b) -> a or b
  */
@@ -1852,8 +1976,14 @@ function* simplifyIdentifiersRenameRef(ast: t.File): Generator<t.File> {
 const simplificationStrategies = [
   {name: 'removeStatements', generator: removeStatements},
   {name: 'removeCallArguments', generator: removeCallArguments},
+  {name: 'removeFunctionParameters', generator: removeFunctionParameters},
   {name: 'removeArrayElements', generator: removeArrayElements},
   {name: 'removeObjectProperties', generator: removeObjectProperties},
+  {name: 'removeArrayPatternElements', generator: removeArrayPatternElements},
+  {
+    name: 'removeObjectPatternProperties',
+    generator: removeObjectPatternProperties,
+  },
   {name: 'removeJSXAttributes', generator: removeJSXAttributes},
   {name: 'removeJSXChildren', generator: removeJSXChildren},
   {name: 'removeJSXFragmentChildren', generator: removeJSXFragmentChildren},

From 22a20e1f2f557b99115d82b639ff5a32b6453cb6 Mon Sep 17 00:00:00 2001
From: Anton Chesnokov <chesnokov.tony@gmail.com>
Date: Wed, 4 Feb 2026 20:07:17 +0400
Subject: [PATCH 2/7] [compiler] Fix setState-in-effect for React.useEffect
 namespace calls (#35377) (#35419)

## Summary
Fix react-hooks/set-state-in-effect false negatives when Hooks are
called via a namespace import (e.g. `import * as React from 'react'` and
`React.useEffect(...))`. The validation now checks the MethodCall
property (the actual hook function) instead of the receiver object.

Issue: Bug: #35377

## How did you test this change?
Added a regression fixture;
Ran tests and verified it reports `EffectSetState` and matches the
expected output.

<img width="461" height="116" alt="Screenshot 2025-12-27 at 14 13 38"
src="https://github.com/user-attachments/assets/fff5aab9-0f2c-40e9-a6a5-b864c3fa6fbd"
/>
---
 .../Validation/ValidateNoSetStateInEffects.ts |  2 +-
 ...-setState-in-useEffect-namespace.expect.md | 42 +++++++++++++++++++
 ...invalid-setState-in-useEffect-namespace.js | 10 +++++
 3 files changed, 53 insertions(+), 1 deletion(-)
 create mode 100644 compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/invalid-setState-in-useEffect-namespace.expect.md
 create mode 100644 compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/invalid-setState-in-useEffect-namespace.js

diff --git a/compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateNoSetStateInEffects.ts b/compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateNoSetStateInEffects.ts
index eba2fdf5bbdd..2457e0d7b99e 100644
--- a/compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateNoSetStateInEffects.ts
+++ b/compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateNoSetStateInEffects.ts
@@ -97,7 +97,7 @@ export function validateNoSetStateInEffects(
         case 'CallExpression': {
           const callee =
             instr.value.kind === 'MethodCall'
-              ? instr.value.receiver
+              ? instr.value.property
               : instr.value.callee;
 
           if (isUseEffectEventType(callee.identifier)) {
diff --git a/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/invalid-setState-in-useEffect-namespace.expect.md b/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/invalid-setState-in-useEffect-namespace.expect.md
new file mode 100644
index 000000000000..b7f823e46d4a
--- /dev/null
+++ b/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/invalid-setState-in-useEffect-namespace.expect.md
@@ -0,0 +1,42 @@
+
+## Input
+
+```javascript
+// @loggerTestOnly @validateNoSetStateInEffects @outputMode:"lint"
+import * as React from 'react';
+
+function Component() {
+  const [state, setState] = React.useState(0);
+  React.useEffect(() => {
+    setState(s => s + 1);
+  });
+  return state;
+}
+
+```
+
+## Code
+
+```javascript
+// @loggerTestOnly @validateNoSetStateInEffects @outputMode:"lint"
+import * as React from "react";
+
+function Component() {
+  const [state, setState] = React.useState(0);
+  React.useEffect(() => {
+    setState((s) => s + 1);
+  });
+  return state;
+}
+
+```
+
+## Logs
+
+```
+{"kind":"CompileError","detail":{"options":{"category":"EffectSetState","reason":"Calling setState synchronously within an effect can trigger cascading renders","description":"Effects are intended to synchronize state between React and external systems such as manually updating the DOM, state management libraries, or other platform APIs. In general, the body of an effect should do one or both of the following:\n* Update external systems with the latest state from React.\n* Subscribe for updates from some external system, calling setState in a callback function when external state changes.\n\nCalling setState synchronously within an effect body causes cascading renders that can hurt performance, and is not recommended. (https://react.dev/learn/you-might-not-need-an-effect)","suggestions":null,"details":[{"kind":"error","loc":{"start":{"line":7,"column":4,"index":200},"end":{"line":7,"column":12,"index":208},"filename":"invalid-setState-in-useEffect-namespace.ts","identifierName":"setState"},"message":"Avoid calling setState() directly within an effect"}]}},"fnLoc":null}
+{"kind":"CompileSuccess","fnLoc":{"start":{"line":4,"column":0,"index":100},"end":{"line":10,"column":1,"index":245},"filename":"invalid-setState-in-useEffect-namespace.ts"},"fnName":"Component","memoSlots":1,"memoBlocks":1,"memoValues":1,"prunedMemoBlocks":1,"prunedMemoValues":1}
+```
+      
+### Eval output
+(kind: exception) Fixture not implemented
\ No newline at end of file
diff --git a/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/invalid-setState-in-useEffect-namespace.js b/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/invalid-setState-in-useEffect-namespace.js
new file mode 100644
index 000000000000..0748c1206f59
--- /dev/null
+++ b/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/invalid-setState-in-useEffect-namespace.js
@@ -0,0 +1,10 @@
+// @loggerTestOnly @validateNoSetStateInEffects @outputMode:"lint"
+import * as React from 'react';
+
+function Component() {
+  const [state, setState] = React.useState(0);
+  React.useEffect(() => {
+    setState(s => s + 1);
+  });
+  return state;
+}

From c137dd6f5484f1bb68a64f07dd0e40d474a29759 Mon Sep 17 00:00:00 2001
From: Jorge Cabiedes <57368278+jorge-cab@users.noreply.github.com>
Date: Wed, 4 Feb 2026 08:24:24 -0800
Subject: [PATCH 3/7] Fix exhaustive deps bug with flow type casting. (#35691)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Summary:
I noticed there's a bug where the lint will recognize the type on a cast
annotation as a missing dependency;

```
        function MyComponent() {
          type ColumnKey = 'id' | 'name';
          type Item = {id: string, name: string};

          const columns = useMemo(
            () => [
              {
                type: 'text',
                key: 'id',
              } as TextColumn<ColumnKey, Item>,
                              ^^^^^^^^ here
            ],
            [],
          );
        }
```

This is due to the AST of AsExpressions being something like:

AsExpression
  └── typeAnnotation: GenericTypeAnnotation
        └── typeParameters: TypeParameterInstantiation
              └── params[0]: GenericTypeAnnotation
                    └── id: Identifier (name: "ColumnKey")

Where `ColumnKey` never has a TypeParameter Annotation. So we need to
consider it to be a flow type due to it belonging to a
GenericTypeAnnotation

Test Plan:
Added unit tests

Before:
```
Test Suites: 1 failed, 2 passed, 3 total
Tests:       2 failed, 5065 passed, 5067 total
Snapshots:   0 total
Time:        16.517 s
Ran all test suites.
error Command failed with exit code 1.
```

After:
```
 PASS  __tests__/ReactCompilerRuleTypescript-test.ts
 PASS  __tests__/ESLintRulesOfHooks-test.js (6.192 s)
 PASS  __tests__/ESLintRuleExhaustiveDeps-test.js (9.97 s)

Test Suites: 3 passed, 3 total
Tests:       5067 passed, 5067 total
Snapshots:   0 total
Time:        10.21 s, estimated 11 s
Ran all test suites.
✨  Done in 12.66s.
```
---
 .../ESLintRuleExhaustiveDeps-test.js          | 19 +++++++++++++++++++
 .../src/rules/ExhaustiveDeps.ts               | 11 +++++++----
 2 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/packages/eslint-plugin-react-hooks/__tests__/ESLintRuleExhaustiveDeps-test.js b/packages/eslint-plugin-react-hooks/__tests__/ESLintRuleExhaustiveDeps-test.js
index b479ce48521c..29e956d314a2 100644
--- a/packages/eslint-plugin-react-hooks/__tests__/ESLintRuleExhaustiveDeps-test.js
+++ b/packages/eslint-plugin-react-hooks/__tests__/ESLintRuleExhaustiveDeps-test.js
@@ -7913,6 +7913,25 @@ const testsFlow = {
         }
       `,
     },
+    // Flow type aliases in type assertions should not be flagged as missing dependencies
+    {
+      code: normalizeIndent`
+        function MyComponent() {
+          type ColumnKey = 'id' | 'name';
+          type Item = {id: string, name: string};
+
+          const columns = useMemo(
+            () => [
+              {
+                type: 'text',
+                key: 'id',
+              } as TextColumn<ColumnKey, Item>,
+            ],
+            [],
+          );
+        }
+      `,
+    },
   ],
   invalid: [
     {
diff --git a/packages/eslint-plugin-react-hooks/src/rules/ExhaustiveDeps.ts b/packages/eslint-plugin-react-hooks/src/rules/ExhaustiveDeps.ts
index 05321ffb46f6..6b790680608d 100644
--- a/packages/eslint-plugin-react-hooks/src/rules/ExhaustiveDeps.ts
+++ b/packages/eslint-plugin-react-hooks/src/rules/ExhaustiveDeps.ts
@@ -21,7 +21,7 @@ import type {
   VariableDeclarator,
 } from 'estree';
 
-import { getAdditionalEffectHooksFromSettings } from '../shared/Utils';
+import {getAdditionalEffectHooksFromSettings} from '../shared/Utils';
 
 type DeclaredDependency = {
   key: string;
@@ -80,7 +80,6 @@ const rule = {
     const rawOptions = context.options && context.options[0];
     const settings = context.settings || {};
 
-
     // Parse the `additionalHooks` regex.
     // Use rule-level additionalHooks if provided, otherwise fall back to settings
     const additionalHooks =
@@ -565,8 +564,12 @@ const rule = {
             continue;
           }
           // Ignore Flow type parameters
-          // @ts-expect-error We don't have flow types
-          if (def.type === 'TypeParameter') {
+          if (
+            // @ts-expect-error We don't have flow types
+            def.type === 'TypeParameter' ||
+            // @ts-expect-error Flow-specific AST node type
+            dependencyNode.parent?.type === 'GenericTypeAnnotation'
+          ) {
             continue;
           }
 

From cf993fb457417e0f20535b1fd42c3f45df966583 Mon Sep 17 00:00:00 2001
From: Hendrik Liebau <mail@hendrik-liebau.de>
Date: Wed, 4 Feb 2026 19:43:23 +0100
Subject: [PATCH 4/7] [Flight] Fix stack overflow in `visitAsyncNode` with deep
 async chains (#35612)

Database libraries like Gel/EdgeDB can create very long linear chains of
async sequences through temporal async sequencing in connection pools.
The recursive traversal of `node.previous` chains in `visitAsyncNode`
causes stack overflow on these deep chains.

The fix converts the `previous` chain traversal from recursive to
iterative. We collect the chain into an array, then process from deepest
to shallowest.

The `awaited` traversal remains recursive since its depth is bounded by
promise dependency depth, not by the number of event loop turns. Each
`awaited` branch still benefits from the iterative `previous` handling
within its own traversal.

I've verified that this fixes the
[repro](https://github.com/jere-co/next-debug) provided in #35246.

closes #35246
---
 .../react-server/src/ReactFlightServer.js     |  76 +-
 .../ReactFlightAsyncDebugInfo-test.js         | 807 +++++++++++-------
 2 files changed, 566 insertions(+), 317 deletions(-)

diff --git a/packages/react-server/src/ReactFlightServer.js b/packages/react-server/src/ReactFlightServer.js
index 6edfbaa4df3e..80d5f3e5c005 100644
--- a/packages/react-server/src/ReactFlightServer.js
+++ b/packages/react-server/src/ReactFlightServer.js
@@ -2345,19 +2345,53 @@ function visitAsyncNode(
   >,
   cutOff: number,
 ): void | null | PromiseNode | IONode {
-  if (visited.has(node)) {
-    // It's possible to visit them same node twice when it's part of both an "awaited" path
-    // and a "previous" path. This also gracefully handles cycles which would be a bug.
-    return visited.get(node);
-  }
-  // Set it as visited early in case we see ourselves before returning.
-  visited.set(node, null);
-  const result = visitAsyncNodeImpl(request, task, node, visited, cutOff);
-  if (result !== null) {
-    // If we ended up with a value, let's use that value for future visits.
-    visited.set(node, result);
+  // Collect the previous chain iteratively instead of recursively to avoid
+  // stack overflow on deep chains. We process from deepest to shallowest so
+  // each node has its previousIONode available.
+  const chain: Array<AsyncSequence> = [];
+  let current: AsyncSequence | null = node;
+
+  while (current !== null) {
+    if (visited.has(current)) {
+      break;
+    }
+    chain.push(current);
+    current = current.previous;
   }
-  return result;
+
+  let previousIONode: void | null | PromiseNode | IONode =
+    current !== null ? visited.get(current) : null;
+
+  // Process from deepest to shallowest (reverse order).
+  for (let i = chain.length - 1; i >= 0; i--) {
+    const n = chain[i];
+    // Set it as visited early in case we see the node again before returning.
+    visited.set(n, null);
+
+    const result = visitAsyncNodeImpl(
+      request,
+      task,
+      n,
+      visited,
+      cutOff,
+      previousIONode,
+    );
+
+    if (result !== null) {
+      // If we ended up with a value, let's use that value for future visits.
+      visited.set(n, result);
+    }
+
+    if (result === undefined) {
+      // Undefined is used as a signal that we found a suitable aborted node
+      // and we don't have to find further aborted nodes.
+      return undefined;
+    }
+
+    previousIONode = result;
+  }
+
+  return previousIONode;
 }
 
 function visitAsyncNodeImpl(
@@ -2369,6 +2403,7 @@ function visitAsyncNodeImpl(
     void | null | PromiseNode | IONode,
   >,
   cutOff: number,
+  previousIONode: void | null | PromiseNode | IONode,
 ): void | null | PromiseNode | IONode {
   if (node.end >= 0 && node.end <= request.timeOrigin) {
     // This was already resolved when we started this render. It must have been either something
@@ -2377,23 +2412,6 @@ function visitAsyncNodeImpl(
     return null;
   }
 
-  let previousIONode: void | null | PromiseNode | IONode = null;
-  // First visit anything that blocked this sequence to start in the first place.
-  if (node.previous !== null) {
-    previousIONode = visitAsyncNode(
-      request,
-      task,
-      node.previous,
-      visited,
-      cutOff,
-    );
-    if (previousIONode === undefined) {
-      // Undefined is used as a signal that we found a suitable aborted node and we don't have to find
-      // further aborted nodes.
-      return undefined;
-    }
-  }
-
   // `found` represents the return value of the following switch statement.
   // We can't use multiple `return` statements in the switch statement
   // since that prevents Closure compiler from inlining `visitAsyncImpl`
diff --git a/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js b/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js
index 2570c0d12e2a..336d797efb61 100644
--- a/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js
+++ b/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js
@@ -5,6 +5,7 @@
 
 import {patchSetImmediate} from '../../../../scripts/jest/patchSetImmediate';
 
+import crypto from 'crypto';
 import fs from 'fs/promises';
 import path from 'path';
 
@@ -160,9 +161,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "Object.<anonymous>",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                129,
+                130,
+                109,
                 109,
-                108,
                 50,
               ],
             ],
@@ -184,9 +185,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                   [
                     "Object.<anonymous>",
                     "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                    129,
+                    130,
+                    109,
                     109,
-                    108,
                     50,
                   ],
                 ],
@@ -195,25 +196,25 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "delay",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  86,
+                  87,
                   12,
-                  85,
+                  86,
                   3,
                 ],
                 [
                   "getData",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  110,
+                  111,
                   13,
-                  109,
+                  110,
                   5,
                 ],
                 [
                   "Component",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  118,
+                  119,
                   26,
-                  117,
+                  118,
                   5,
                 ],
               ],
@@ -232,9 +233,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "Object.<anonymous>",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  129,
+                  130,
+                  109,
                   109,
-                  108,
                   50,
                 ],
               ],
@@ -243,17 +244,17 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "getData",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                110,
+                111,
                 13,
-                109,
+                110,
                 5,
               ],
               [
                 "Component",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                118,
+                119,
                 26,
-                117,
+                118,
                 5,
               ],
             ],
@@ -278,9 +279,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                   [
                     "Object.<anonymous>",
                     "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                    129,
+                    130,
+                    109,
                     109,
-                    108,
                     50,
                   ],
                 ],
@@ -289,25 +290,25 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "delay",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  86,
+                  87,
                   12,
-                  85,
+                  86,
                   3,
                 ],
                 [
                   "getData",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  111,
+                  112,
                   21,
-                  109,
+                  110,
                   5,
                 ],
                 [
                   "Component",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  118,
+                  119,
                   20,
-                  117,
+                  118,
                   5,
                 ],
               ],
@@ -326,9 +327,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "Object.<anonymous>",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  129,
+                  130,
+                  109,
                   109,
-                  108,
                   50,
                 ],
               ],
@@ -337,17 +338,17 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "getData",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                113,
+                114,
                 21,
-                109,
+                110,
                 5,
               ],
               [
                 "Component",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                118,
+                119,
                 20,
-                117,
+                118,
                 5,
               ],
             ],
@@ -367,9 +368,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "Component",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                120,
+                121,
                 60,
-                117,
+                118,
                 5,
               ],
             ],
@@ -391,9 +392,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                   [
                     "Object.<anonymous>",
                     "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                    129,
+                    130,
+                    109,
                     109,
-                    108,
                     50,
                   ],
                 ],
@@ -402,17 +403,17 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "delay",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  86,
+                  87,
                   12,
-                  85,
+                  86,
                   3,
                 ],
                 [
                   "getData",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  111,
+                  112,
                   21,
-                  109,
+                  110,
                   5,
                 ],
               ],
@@ -431,9 +432,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "Component",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  120,
+                  121,
                   60,
-                  117,
+                  118,
                   5,
                 ],
               ],
@@ -442,9 +443,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "InnerComponent",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                126,
+                127,
                 35,
-                123,
+                124,
                 5,
               ],
             ],
@@ -625,9 +626,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "Object.<anonymous>",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                589,
+                590,
                 40,
-                570,
+                571,
                 49,
               ],
               [
@@ -657,9 +658,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                   [
                     "Object.<anonymous>",
                     "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                    589,
+                    590,
                     40,
-                    570,
+                    571,
                     49,
                   ],
                   [
@@ -676,25 +677,25 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "delay",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  86,
+                  87,
                   12,
-                  85,
+                  86,
                   3,
                 ],
                 [
                   "getData",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  572,
+                  573,
                   13,
-                  571,
+                  572,
                   5,
                 ],
                 [
                   "Component",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  577,
+                  578,
                   36,
-                  576,
+                  577,
                   5,
                 ],
               ],
@@ -713,9 +714,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "Object.<anonymous>",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  589,
+                  590,
                   40,
-                  570,
+                  571,
                   49,
                 ],
                 [
@@ -732,17 +733,17 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "getData",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                572,
+                573,
                 13,
-                571,
+                572,
                 5,
               ],
               [
                 "Component",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                577,
+                578,
                 36,
-                576,
+                577,
                 5,
               ],
             ],
@@ -762,9 +763,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "Component",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                579,
+                580,
                 60,
-                576,
+                577,
                 5,
               ],
             ],
@@ -783,9 +784,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                   [
                     "Object.<anonymous>",
                     "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                    589,
+                    590,
                     40,
-                    570,
+                    571,
                     49,
                   ],
                   [
@@ -802,25 +803,25 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "delay",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  86,
+                  87,
                   12,
-                  85,
+                  86,
                   3,
                 ],
                 [
                   "getData",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  572,
+                  573,
                   13,
-                  571,
+                  572,
                   5,
                 ],
                 [
                   "Component",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  578,
+                  579,
                   22,
-                  576,
+                  577,
                   5,
                 ],
               ],
@@ -839,9 +840,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "Component",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  579,
+                  580,
                   60,
-                  576,
+                  577,
                   5,
                 ],
               ],
@@ -850,9 +851,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "InnerComponent",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                585,
+                586,
                 40,
-                582,
+                583,
                 5,
               ],
             ],
@@ -927,9 +928,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "Object.<anonymous>",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                896,
+                897,
                 109,
-                883,
+                884,
                 80,
               ],
             ],
@@ -948,9 +949,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                   [
                     "Object.<anonymous>",
                     "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                    896,
+                    897,
                     109,
-                    883,
+                    884,
                     80,
                   ],
                 ],
@@ -967,9 +968,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "Object.<anonymous>",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  896,
+                  897,
                   109,
-                  883,
+                  884,
                   80,
                 ],
               ],
@@ -1041,9 +1042,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "Object.<anonymous>",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                1010,
+                1011,
                 109,
-                1001,
+                1002,
                 94,
               ],
             ],
@@ -1114,9 +1115,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "Object.<anonymous>",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                1083,
+                1084,
                 109,
-                1059,
+                1060,
                 50,
               ],
             ],
@@ -1198,9 +1199,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "Object.<anonymous>",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                1167,
+                1168,
                 109,
-                1150,
+                1151,
                 63,
               ],
             ],
@@ -1217,17 +1218,17 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "fetchThirdParty",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                93,
+                94,
                 40,
-                91,
+                92,
                 3,
               ],
               [
                 "Component",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                1163,
+                1164,
                 24,
-                1162,
+                1163,
                 5,
               ],
             ],
@@ -1249,17 +1250,17 @@ describe('ReactFlightAsyncDebugInfo', () => {
                   [
                     "fetchThirdParty",
                     "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                    93,
+                    94,
                     40,
-                    91,
+                    92,
                     3,
                   ],
                   [
                     "Component",
                     "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                    1163,
+                    1164,
                     24,
-                    1162,
+                    1163,
                     5,
                   ],
                 ],
@@ -1268,25 +1269,25 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "delay",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  86,
+                  87,
                   12,
-                  85,
+                  86,
                   3,
                 ],
                 [
                   "getData",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  1152,
+                  1153,
                   13,
-                  1151,
+                  1152,
                   5,
                 ],
                 [
                   "ThirdPartyComponent",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  1158,
+                  1159,
                   24,
-                  1157,
+                  1158,
                   5,
                 ],
               ],
@@ -1305,17 +1306,17 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "fetchThirdParty",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  93,
+                  94,
                   40,
-                  91,
+                  92,
                   3,
                 ],
                 [
                   "Component",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  1163,
+                  1164,
                   24,
-                  1162,
+                  1163,
                   5,
                 ],
               ],
@@ -1324,17 +1325,17 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "getData",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                1152,
+                1153,
                 13,
-                1151,
+                1152,
                 5,
               ],
               [
                 "ThirdPartyComponent",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                1158,
+                1159,
                 24,
-                1157,
+                1158,
                 5,
               ],
             ],
@@ -1359,17 +1360,17 @@ describe('ReactFlightAsyncDebugInfo', () => {
                   [
                     "fetchThirdParty",
                     "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                    93,
+                    94,
                     40,
-                    91,
+                    92,
                     3,
                   ],
                   [
                     "Component",
                     "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                    1163,
+                    1164,
                     24,
-                    1162,
+                    1163,
                     5,
                   ],
                 ],
@@ -1378,25 +1379,25 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "delay",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  86,
+                  87,
                   12,
-                  85,
+                  86,
                   3,
                 ],
                 [
                   "getData",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  1153,
+                  1154,
                   13,
-                  1151,
+                  1152,
                   5,
                 ],
                 [
                   "ThirdPartyComponent",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  1158,
+                  1159,
                   18,
-                  1157,
+                  1158,
                   5,
                 ],
               ],
@@ -1415,17 +1416,17 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "fetchThirdParty",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  93,
+                  94,
                   40,
-                  91,
+                  92,
                   3,
                 ],
                 [
                   "Component",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  1163,
+                  1164,
                   24,
-                  1162,
+                  1163,
                   5,
                 ],
               ],
@@ -1434,17 +1435,17 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "getData",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                1153,
+                1154,
                 13,
-                1151,
+                1152,
                 5,
               ],
               [
                 "ThirdPartyComponent",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                1158,
+                1159,
                 18,
-                1157,
+                1158,
                 5,
               ],
             ],
@@ -1544,9 +1545,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "Object.<anonymous>",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                1508,
+                1509,
                 40,
-                1491,
+                1492,
                 62,
               ],
               [
@@ -1576,9 +1577,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                   [
                     "Object.<anonymous>",
                     "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                    1508,
+                    1509,
                     40,
-                    1491,
+                    1492,
                     62,
                   ],
                   [
@@ -1595,25 +1596,25 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "delay",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  86,
+                  87,
                   12,
-                  85,
+                  86,
                   3,
                 ],
                 [
                   "getData",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  1493,
+                  1494,
                   13,
-                  1492,
+                  1493,
                   25,
                 ],
                 [
                   "Component",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  1503,
+                  1504,
                   13,
-                  1502,
+                  1503,
                   5,
                 ],
               ],
@@ -1632,9 +1633,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "Object.<anonymous>",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  1508,
+                  1509,
                   40,
-                  1491,
+                  1492,
                   62,
                 ],
                 [
@@ -1651,17 +1652,17 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "getData",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                1493,
+                1494,
                 13,
-                1492,
+                1493,
                 25,
               ],
               [
                 "Component",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                1503,
+                1504,
                 13,
-                1502,
+                1503,
                 5,
               ],
             ],
@@ -1681,9 +1682,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "Component",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                1504,
+                1505,
                 60,
-                1502,
+                1503,
                 5,
               ],
             ],
@@ -1705,9 +1706,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                   [
                     "Object.<anonymous>",
                     "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                    1508,
+                    1509,
                     40,
-                    1491,
+                    1492,
                     62,
                   ],
                   [
@@ -1724,25 +1725,25 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "delay",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  86,
+                  87,
                   12,
-                  85,
+                  86,
                   3,
                 ],
                 [
                   "getData",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  1493,
+                  1494,
                   13,
-                  1492,
+                  1493,
                   25,
                 ],
                 [
                   "Component",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  1503,
+                  1504,
                   13,
-                  1502,
+                  1503,
                   5,
                 ],
               ],
@@ -1761,9 +1762,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "Component",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  1504,
+                  1505,
                   60,
-                  1502,
+                  1503,
                   5,
                 ],
               ],
@@ -1772,9 +1773,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "Child",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                1498,
+                1499,
                 28,
-                1497,
+                1498,
                 5,
               ],
             ],
@@ -1857,9 +1858,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "Object.<anonymous>",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                1821,
+                1822,
                 40,
-                1805,
+                1806,
                 57,
               ],
               [
@@ -1889,9 +1890,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                   [
                     "Object.<anonymous>",
                     "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                    1821,
+                    1822,
                     40,
-                    1805,
+                    1806,
                     57,
                   ],
                   [
@@ -1908,25 +1909,25 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "delay",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  86,
+                  87,
                   12,
-                  85,
+                  86,
                   3,
                 ],
                 [
                   "getData",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  1807,
+                  1808,
                   13,
-                  1806,
+                  1807,
                   25,
                 ],
                 [
                   "Component",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  1816,
+                  1817,
                   23,
-                  1815,
+                  1816,
                   5,
                 ],
               ],
@@ -1945,9 +1946,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "Object.<anonymous>",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  1821,
+                  1822,
                   40,
-                  1805,
+                  1806,
                   57,
                 ],
                 [
@@ -1964,17 +1965,17 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "getData",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                1807,
+                1808,
                 13,
-                1806,
+                1807,
                 25,
               ],
               [
                 "Component",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                1816,
+                1817,
                 23,
-                1815,
+                1816,
                 5,
               ],
             ],
@@ -1994,9 +1995,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "Component",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                1817,
+                1818,
                 60,
-                1815,
+                1816,
                 5,
               ],
             ],
@@ -2015,9 +2016,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                   [
                     "Object.<anonymous>",
                     "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                    1821,
+                    1822,
                     40,
-                    1805,
+                    1806,
                     57,
                   ],
                   [
@@ -2034,25 +2035,25 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "delay",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  86,
+                  87,
                   12,
-                  85,
+                  86,
                   3,
                 ],
                 [
                   "getData",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  1807,
+                  1808,
                   13,
-                  1806,
+                  1807,
                   25,
                 ],
                 [
                   "Component",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  1816,
+                  1817,
                   23,
-                  1815,
+                  1816,
                   5,
                 ],
               ],
@@ -2066,9 +2067,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "Component",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                1817,
+                1818,
                 60,
-                1815,
+                1816,
                 5,
               ],
             ],
@@ -2153,9 +2154,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "Object.<anonymous>",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                2117,
+                2118,
                 40,
-                2099,
+                2100,
                 80,
               ],
               [
@@ -2185,9 +2186,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                   [
                     "Object.<anonymous>",
                     "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                    2117,
+                    2118,
                     40,
-                    2099,
+                    2100,
                     80,
                   ],
                   [
@@ -2204,25 +2205,25 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "delay",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  86,
+                  87,
                   12,
-                  85,
+                  86,
                   3,
                 ],
                 [
                   "delayTrice",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  2107,
+                  2108,
                   13,
-                  2105,
+                  2106,
                   5,
                 ],
                 [
                   "Bar",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  2112,
+                  2113,
                   13,
-                  2111,
+                  2112,
                   5,
                 ],
               ],
@@ -2241,9 +2242,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "Object.<anonymous>",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  2117,
+                  2118,
                   40,
-                  2099,
+                  2100,
                   80,
                 ],
                 [
@@ -2260,17 +2261,17 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "delayTrice",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                2107,
+                2108,
                 13,
-                2105,
+                2106,
                 5,
               ],
               [
                 "Bar",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                2112,
+                2113,
                 13,
-                2111,
+                2112,
                 5,
               ],
             ],
@@ -2292,9 +2293,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                   [
                     "Object.<anonymous>",
                     "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                    2117,
+                    2118,
                     40,
-                    2099,
+                    2100,
                     80,
                   ],
                   [
@@ -2311,33 +2312,33 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "delay",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  86,
+                  87,
                   12,
-                  85,
+                  86,
                   3,
                 ],
                 [
                   "delayTwice",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  2101,
+                  2102,
                   13,
-                  2100,
+                  2101,
                   5,
                 ],
                 [
                   "delayTrice",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  2106,
+                  2107,
                   15,
-                  2105,
+                  2106,
                   5,
                 ],
                 [
                   "Bar",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  2112,
+                  2113,
                   13,
-                  2111,
+                  2112,
                   5,
                 ],
               ],
@@ -2356,9 +2357,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "Object.<anonymous>",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  2117,
+                  2118,
                   40,
-                  2099,
+                  2100,
                   80,
                 ],
                 [
@@ -2375,25 +2376,25 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "delayTwice",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                2101,
+                2102,
                 13,
-                2100,
+                2101,
                 5,
               ],
               [
                 "delayTrice",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                2106,
+                2107,
                 15,
-                2105,
+                2106,
                 5,
               ],
               [
                 "Bar",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                2112,
+                2113,
                 13,
-                2111,
+                2112,
                 5,
               ],
             ],
@@ -2415,9 +2416,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                   [
                     "Object.<anonymous>",
                     "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                    2117,
+                    2118,
                     40,
-                    2099,
+                    2100,
                     80,
                   ],
                   [
@@ -2434,17 +2435,17 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "delay",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  86,
+                  87,
                   12,
-                  85,
+                  86,
                   3,
                 ],
                 [
                   "delayTwice",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  2102,
+                  2103,
                   13,
-                  2100,
+                  2101,
                   5,
                 ],
               ],
@@ -2463,9 +2464,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "Object.<anonymous>",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  2117,
+                  2118,
                   40,
-                  2099,
+                  2100,
                   80,
                 ],
                 [
@@ -2482,9 +2483,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "delayTwice",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                2102,
+                2103,
                 13,
-                2100,
+                2101,
                 5,
               ],
             ],
@@ -2557,9 +2558,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "Object.<anonymous>",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                2526,
+                2527,
                 109,
-                2515,
+                2516,
                 58,
               ],
             ],
@@ -2581,9 +2582,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                   [
                     "Object.<anonymous>",
                     "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                    2526,
+                    2527,
                     109,
-                    2515,
+                    2516,
                     58,
                   ],
                 ],
@@ -2592,25 +2593,25 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "delay",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  86,
+                  87,
                   12,
-                  85,
+                  86,
                   3,
                 ],
                 [
                   "getData",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  2517,
+                  2518,
                   14,
-                  2516,
+                  2517,
                   5,
                 ],
                 [
                   "Component",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  2523,
+                  2524,
                   20,
-                  2522,
+                  2523,
                   5,
                 ],
               ],
@@ -2629,9 +2630,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "Object.<anonymous>",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  2526,
+                  2527,
                   109,
-                  2515,
+                  2516,
                   58,
                 ],
               ],
@@ -2640,17 +2641,17 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "getData",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                2517,
+                2518,
                 23,
-                2516,
+                2517,
                 5,
               ],
               [
                 "Component",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                2523,
+                2524,
                 20,
-                2522,
+                2523,
                 5,
               ],
             ],
@@ -2729,9 +2730,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "Object.<anonymous>",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                2693,
+                2694,
                 40,
-                2681,
+                2682,
                 56,
               ],
               [
@@ -2761,9 +2762,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                   [
                     "Object.<anonymous>",
                     "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                    2693,
+                    2694,
                     40,
-                    2681,
+                    2682,
                     56,
                   ],
                   [
@@ -2780,17 +2781,17 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "delay",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  86,
+                  87,
                   12,
-                  85,
+                  86,
                   3,
                 ],
                 [
                   "Component",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  2689,
+                  2690,
                   20,
-                  2688,
+                  2689,
                   5,
                 ],
               ],
@@ -2809,9 +2810,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "Object.<anonymous>",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  2693,
+                  2694,
                   40,
-                  2681,
+                  2682,
                   56,
                 ],
                 [
@@ -2828,9 +2829,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "Component",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                2689,
+                2690,
                 20,
-                2688,
+                2689,
                 5,
               ],
             ],
@@ -2923,9 +2924,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "Object.<anonymous>",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                2882,
+                2883,
                 40,
-                2861,
+                2862,
                 42,
               ],
               [
@@ -2955,9 +2956,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                   [
                     "Object.<anonymous>",
                     "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                    2882,
+                    2883,
                     40,
-                    2861,
+                    2862,
                     42,
                   ],
                   [
@@ -2974,17 +2975,17 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  2868,
+                  2869,
                   15,
-                  2867,
+                  2868,
                   15,
                 ],
                 [
                   "Component",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  2877,
+                  2878,
                   19,
-                  2876,
+                  2877,
                   5,
                 ],
               ],
@@ -3003,9 +3004,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "Object.<anonymous>",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  2882,
+                  2883,
                   40,
-                  2861,
+                  2862,
                   42,
                 ],
                 [
@@ -3022,17 +3023,17 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                2868,
+                2869,
                 15,
-                2867,
+                2868,
                 15,
               ],
               [
                 "Component",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                2877,
+                2878,
                 19,
-                2876,
+                2877,
                 5,
               ],
             ],
@@ -3054,9 +3055,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                   [
                     "Object.<anonymous>",
                     "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                    2882,
+                    2883,
                     40,
-                    2861,
+                    2862,
                     42,
                   ],
                   [
@@ -3073,9 +3074,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "Component",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  2877,
+                  2878,
                   25,
-                  2876,
+                  2877,
                   5,
                 ],
               ],
@@ -3094,9 +3095,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "Object.<anonymous>",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  2882,
+                  2883,
                   40,
-                  2861,
+                  2862,
                   42,
                 ],
                 [
@@ -3113,9 +3114,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "Component",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                2877,
+                2878,
                 25,
-                2876,
+                2877,
                 5,
               ],
             ],
@@ -3191,9 +3192,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "Object.<anonymous>",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                3158,
+                3159,
                 19,
-                3146,
+                3147,
                 36,
               ],
             ],
@@ -3215,9 +3216,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                   [
                     "Object.<anonymous>",
                     "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                    3158,
+                    3159,
                     19,
-                    3146,
+                    3147,
                     36,
                   ],
                 ],
@@ -3226,9 +3227,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "Component",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  3150,
+                  3151,
                   7,
-                  3148,
+                  3149,
                   5,
                 ],
               ],
@@ -3247,9 +3248,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
                 [
                   "Object.<anonymous>",
                   "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                  3158,
+                  3159,
                   19,
-                  3146,
+                  3147,
                   36,
                 ],
               ],
@@ -3258,9 +3259,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "Component",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                3152,
+                3153,
                 7,
-                3148,
+                3149,
                 5,
               ],
             ],
@@ -3385,9 +3386,9 @@ describe('ReactFlightAsyncDebugInfo', () => {
               [
                 "Component",
                 "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
-                3303,
+                3304,
                 20,
-                3302,
+                3303,
                 5,
               ],
             ],
@@ -3402,4 +3403,234 @@ describe('ReactFlightAsyncDebugInfo', () => {
       `);
     }
   });
+
+  // Regression test: Database clients like Gel/EdgeDB with connection pools can
+  // create very long chains of async nodes linked via `previous` pointers.
+  // visitAsyncNode must handle chains of thousands of nodes without stack
+  // overflow.
+  //
+  // The pattern that creates deep chains (Event/messageWaiter):
+  // 1. Create a Promise resolved by an I/O callback
+  // 2. Start I/O, await the Promise
+  // 3. When I/O resolves, code continues in the callback context
+  // 4. The next iteration's async nodes link via `previous` to the current
+  //    context
+  it('handles deep linear async chains from connection pool patterns', async () => {
+    // Replicate Gel's Event class pattern, a Promise resolved externally by I/O
+    class Event {
+      constructor() {
+        this._resolve = null;
+        this._promise = new Promise(resolve => {
+          this._resolve = resolve;
+        });
+      }
+
+      wait() {
+        return this._promise;
+      }
+
+      set() {
+        this._resolve(true);
+      }
+    }
+
+    // Replicate Gel's _waitForMessage pattern:
+    // Each iteration creates an Event, schedules I/O to resolve it, and awaits.
+    // The next iteration runs in the context of the previous I/O callback,
+    // creating linear chains of previous pointers.
+    async function buildLinearChain(depth) {
+      for (let i = 0; i < depth; i++) {
+        const event = new Event();
+        // crypto.randomBytes uses the thread pool and is recognized as I/O
+        // (type='RANDOMBYTESREQUEST'). It's much faster than setTimeout.
+        crypto.randomBytes(1, () => event.set());
+        await event.wait();
+        // After this await resolves, we're in the crypto callback's context
+        // The next Event will be created in this context, linking prev pointers
+      }
+    }
+
+    async function Component() {
+      // Use 2000 iterations to ensure regression would be caught. Using
+      // crypto.randomBytes keeps the test fast.
+      await buildLinearChain(2000);
+      return 'done';
+    }
+
+    const stream = ReactServerDOMServer.renderToPipeableStream(
+      <Component />,
+      {},
+      {
+        filterStackFrame: (filename, functionName) => {
+          // Custom filter that treats Event and buildLinearChain as library
+          // code. This simulates how real DB libraries like Gel/EdgeDB would be
+          // filtered.
+          if (
+            functionName === 'new Event' ||
+            functionName === 'buildLinearChain' ||
+            functionName === '_loop' // Generated name for the for-loop
+          ) {
+            return false;
+          }
+          return filterStackFrame(filename, functionName);
+        },
+      },
+    );
+
+    const readable = new Stream.PassThrough(streamOptions);
+
+    const result = ReactServerDOMClient.createFromNodeStream(readable, {
+      moduleMap: {},
+      moduleLoading: {},
+    });
+    stream.pipe(readable);
+
+    // This should not throw "Maximum call stack size exceeded"
+    expect(await result).toBe('done');
+
+    await finishLoadingStream(readable);
+    if (
+      __DEV__ &&
+      gate(
+        flags =>
+          flags.enableComponentPerformanceTrack && flags.enableAsyncDebugInfo,
+      )
+    ) {
+      // With library code filtered out, we should only see the Component's
+      // debug info, not thousands of entries from the internal
+      // Event/buildLinearChain operations.
+      expect(getDebugInfo(result)).toMatchInlineSnapshot(`
+        [
+          {
+            "time": 0,
+          },
+          {
+            "env": "Server",
+            "key": null,
+            "name": "Component",
+            "props": {},
+            "stack": [
+              [
+                "Object.<anonymous>",
+                "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
+                3461,
+                40,
+                3418,
+                72,
+              ],
+              [
+                "new Promise",
+                "",
+                0,
+                0,
+                0,
+                0,
+              ],
+            ],
+          },
+          {
+            "time": 0,
+          },
+          {
+            "awaited": {
+              "end": 0,
+              "env": "Server",
+              "name": "buildLinearChain",
+              "owner": {
+                "env": "Server",
+                "key": null,
+                "name": "Component",
+                "props": {},
+                "stack": [
+                  [
+                    "Object.<anonymous>",
+                    "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
+                    3461,
+                    40,
+                    3418,
+                    72,
+                  ],
+                  [
+                    "new Promise",
+                    "",
+                    0,
+                    0,
+                    0,
+                    0,
+                  ],
+                ],
+              },
+              "stack": [
+                [
+                  "Component",
+                  "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
+                  3456,
+                  13,
+                  3453,
+                  5,
+                ],
+              ],
+              "start": 0,
+              "value": {
+                "value": undefined,
+              },
+            },
+            "env": "Server",
+            "owner": {
+              "env": "Server",
+              "key": null,
+              "name": "Component",
+              "props": {},
+              "stack": [
+                [
+                  "Object.<anonymous>",
+                  "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
+                  3461,
+                  40,
+                  3418,
+                  72,
+                ],
+                [
+                  "new Promise",
+                  "",
+                  0,
+                  0,
+                  0,
+                  0,
+                ],
+              ],
+            },
+            "stack": [
+              [
+                "Component",
+                "/packages/react-server/src/__tests__/ReactFlightAsyncDebugInfo-test.js",
+                3456,
+                13,
+                3453,
+                5,
+              ],
+            ],
+          },
+          {
+            "time": 0,
+          },
+          {
+            "time": 0,
+          },
+          {
+            "awaited": {
+              "byteSize": 0,
+              "end": 0,
+              "name": "rsc stream",
+              "owner": null,
+              "start": 0,
+              "value": {
+                "value": "stream",
+              },
+            },
+          },
+        ]
+      `);
+    }
+  });
 });

From 6913ea4d28229d066603bff9fc1170334e151a4a Mon Sep 17 00:00:00 2001
From: Ricky <rickhanlonii@gmail.com>
Date: Wed, 4 Feb 2026 13:58:34 -0500
Subject: [PATCH 5/7] [flags] Add `enableParallelTransitions` (#35392)

## Overview

Adds a feature flag `enableParallelTransitions` to experiment with
engantling transitions less often.

## Motivation

Currently we over-entangle transition lanes.

It's a common misunderstanding that React entangles all transitions,
always. We actually will complete transitions independently in many
cases. For example, [this
codepen](https://codepen.io/GabbeV/pen/pvyKBrM) from
[@gabbev](https://bsky.app/profile/gabbev.bsky.social/post/3m6uq2abihk2x)
shows transitions completing independently.

However, in many cases we entangle when we don't need to, instead of
letting the independent transitons complete independently. We still want
to entangle for updates that happen on the same queue.

## Example

As an example of what this flag would change, consider two independent
counter components:

```js
function Counter({ label }) {
  const [count, setCount] = useState(0);

  return (
    <div>
      <span>{use(readCache(`${label} ${count}`))} </span>
      <Button
        action={() => {
          setCount((c) => c + 1);
        }}
      >
        Next {label}
      </Button>
    </div>
  );
}
```
```js
export default function App() {
  return (
    <>
      <Counter label="A" />
      <Counter label="B" />
    </>
  );
}
```

### Before
The behavior today is to entange them, meaning they always commit
together:



https://github.com/user-attachments/assets/adead60e-8a98-4a20-a440-1efdf85b2142

### After

In this experiment, they will complete independently (if they don't
depend on each other):


https://github.com/user-attachments/assets/181632b5-3c92-4a29-a571-3637f3fab8cd

## Early Research

This change is in early research, and is not in the experimental
channel. We're going to experiment with this at Meta to understand how
much of a breaking change, and how beneficial it is before commiting to
shipping it in experimental and beyond.
---
 .../react-reconciler/src/ReactFiberLane.js    |   4 +
 .../src/ReactFiberWorkLoop.js                 |   6 +
 .../src/__tests__/ReactDeferredValue-test.js  | 193 ++++++++++-
 .../src/__tests__/ReactTransition-test.js     | 313 ++++++++++++++++++
 packages/shared/ReactFeatureFlags.js          |   3 +
 .../forks/ReactFeatureFlags.native-fb.js      |   1 +
 .../forks/ReactFeatureFlags.native-oss.js     |   1 +
 .../forks/ReactFeatureFlags.test-renderer.js  |   1 +
 ...actFeatureFlags.test-renderer.native-fb.js |   1 +
 .../ReactFeatureFlags.test-renderer.www.js    |   1 +
 .../forks/ReactFeatureFlags.www-dynamic.js    |   1 +
 .../shared/forks/ReactFeatureFlags.www.js     |   1 +
 12 files changed, 517 insertions(+), 9 deletions(-)

diff --git a/packages/react-reconciler/src/ReactFiberLane.js b/packages/react-reconciler/src/ReactFiberLane.js
index b54047cb4aa7..987f0338ad1a 100644
--- a/packages/react-reconciler/src/ReactFiberLane.js
+++ b/packages/react-reconciler/src/ReactFiberLane.js
@@ -29,6 +29,7 @@ import {
   disableLegacyMode,
   enableDefaultTransitionIndicator,
   enableGestureTransition,
+  enableParallelTransitions,
 } from 'shared/ReactFeatureFlags';
 import {isDevToolsPresent} from './ReactFiberDevToolsHook';
 import {clz32} from './clz32';
@@ -208,6 +209,9 @@ function getHighestPriorityLanes(lanes: Lanes | Lane): Lanes {
     case TransitionLane8:
     case TransitionLane9:
     case TransitionLane10:
+      if (enableParallelTransitions) {
+        return getHighestPriorityLane(lanes);
+      }
       return lanes & TransitionUpdateLanes;
     case TransitionLane11:
     case TransitionLane12:
diff --git a/packages/react-reconciler/src/ReactFiberWorkLoop.js b/packages/react-reconciler/src/ReactFiberWorkLoop.js
index b03f5eff159c..d055b271ad77 100644
--- a/packages/react-reconciler/src/ReactFiberWorkLoop.js
+++ b/packages/react-reconciler/src/ReactFiberWorkLoop.js
@@ -58,6 +58,7 @@ import {
   enableViewTransition,
   enableGestureTransition,
   enableDefaultTransitionIndicator,
+  enableParallelTransitions,
 } from 'shared/ReactFeatureFlags';
 import {resetOwnerStackLimit} from 'shared/ReactOwnerStackReset';
 import ReactSharedInternals from 'shared/ReactSharedInternals';
@@ -1777,6 +1778,11 @@ function markRootSuspended(
   spawnedLane: Lane,
   didAttemptEntireTree: boolean,
 ) {
+  if (enableParallelTransitions) {
+    // When suspending, we should always mark the entangled lanes as suspended.
+    suspendedLanes = getEntangledLanes(root, suspendedLanes);
+  }
+
   // When suspending, we should always exclude lanes that were pinged or (more
   // rarely, since we try to avoid it) updated during the render phase.
   suspendedLanes = removeLanes(suspendedLanes, workInProgressRootPingedLanes);
diff --git a/packages/react-reconciler/src/__tests__/ReactDeferredValue-test.js b/packages/react-reconciler/src/__tests__/ReactDeferredValue-test.js
index e4fe796fd353..3a348307f4cd 100644
--- a/packages/react-reconciler/src/__tests__/ReactDeferredValue-test.js
+++ b/packages/react-reconciler/src/__tests__/ReactDeferredValue-test.js
@@ -420,9 +420,13 @@ describe('ReactDeferredValue', () => {
         // The initial value suspended, so we attempt the final value, which
         // also suspends.
         'Suspend! [Final]',
-        // pre-warming
-        'Suspend! [Loading...]',
-        'Suspend! [Final]',
+        ...(gate('enableParallelTransitions')
+          ? []
+          : [
+              // Existing bug: Unnecessary pre-warm.
+              'Suspend! [Loading...]',
+              'Suspend! [Final]',
+            ]),
       ]);
       expect(root).toMatchRenderedOutput(null);
 
@@ -439,6 +443,171 @@ describe('ReactDeferredValue', () => {
     },
   );
 
+  it(
+    'if a suspended render spawns a deferred task that suspends on a sibling, ' +
+      'we can finish the original task if the original sibling loads first',
+    async () => {
+      function App() {
+        const deferredText = useDeferredValue(`Final`, `Loading...`);
+        return (
+          <>
+            <AsyncText text={deferredText} />{' '}
+            <AsyncText text={`Sibling: ${deferredText}`} />
+          </>
+        );
+      }
+
+      const root = ReactNoop.createRoot();
+      await act(() => root.render(<App text="a" />));
+      assertLog([
+        'Suspend! [Loading...]',
+        // The initial value suspended, so we attempt the final value, which
+        // also suspends.
+        'Suspend! [Final]',
+        'Suspend! [Sibling: Final]',
+        ...(gate('enableParallelTransitions')
+          ? [
+              // With parallel transitions,
+              // we do not continue pre-warming.
+            ]
+          : [
+              'Suspend! [Loading...]',
+              'Suspend! [Sibling: Loading...]',
+              'Suspend! [Final]',
+              'Suspend! [Sibling: Final]',
+            ]),
+      ]);
+      expect(root).toMatchRenderedOutput(null);
+
+      // The final value loads, so we can skip the initial value entirely.
+      await act(() => {
+        resolveText('Final');
+      });
+      assertLog(['Final', 'Suspend! [Sibling: Final]']);
+      expect(root).toMatchRenderedOutput(null);
+
+      // The initial value resolves first, so we render that.
+      await act(() => resolveText('Loading...'));
+      assertLog([
+        'Loading...',
+        'Suspend! [Sibling: Loading...]',
+        'Final',
+        'Suspend! [Sibling: Final]',
+        ...(gate('enableParallelTransitions')
+          ? [
+              // With parallel transitions,
+              // we do not continue pre-warming.
+            ]
+          : [
+              'Loading...',
+              'Suspend! [Sibling: Loading...]',
+              'Final',
+              'Suspend! [Sibling: Final]',
+            ]),
+      ]);
+      expect(root).toMatchRenderedOutput(null);
+
+      // The Final sibling loads, we're unblocked and commit.
+      await act(() => {
+        resolveText('Sibling: Final');
+      });
+      assertLog(['Final', 'Sibling: Final']);
+      expect(root).toMatchRenderedOutput('Final Sibling: Final');
+
+      // We already rendered the Final value, so nothing happens
+      await act(() => {
+        resolveText('Sibling: Loading...');
+      });
+      assertLog([]);
+      expect(root).toMatchRenderedOutput('Final Sibling: Final');
+    },
+  );
+
+  it(
+    'if a suspended render spawns a deferred task that suspends on a sibling,' +
+      ' we can switch to the deferred task without finishing the original one',
+    async () => {
+      function App() {
+        const deferredText = useDeferredValue(`Final`, `Loading...`);
+        return (
+          <>
+            <AsyncText text={deferredText} />{' '}
+            <AsyncText text={`Sibling: ${deferredText}`} />
+          </>
+        );
+      }
+
+      const root = ReactNoop.createRoot();
+      await act(() => root.render(<App text="a" />));
+      assertLog([
+        'Suspend! [Loading...]',
+        // The initial value suspended, so we attempt the final value, which
+        // also suspends.
+        'Suspend! [Final]',
+        'Suspend! [Sibling: Final]',
+        ...(gate('enableParallelTransitions')
+          ? [
+              // With parallel transitions,
+              // we do not continue pre-warming.
+            ]
+          : [
+              'Suspend! [Loading...]',
+              'Suspend! [Sibling: Loading...]',
+              'Suspend! [Final]',
+              'Suspend! [Sibling: Final]',
+            ]),
+      ]);
+      expect(root).toMatchRenderedOutput(null);
+
+      // The final value loads, so we can skip the initial value entirely.
+      await act(() => {
+        resolveText('Final');
+      });
+      assertLog(['Final', 'Suspend! [Sibling: Final]']);
+      expect(root).toMatchRenderedOutput(null);
+
+      // The initial value resolves first, so we render that.
+      await act(() => resolveText('Loading...'));
+      assertLog([
+        'Loading...',
+        'Suspend! [Sibling: Loading...]',
+        'Final',
+        'Suspend! [Sibling: Final]',
+        ...(gate('enableParallelTransitions')
+          ? [
+              // With parallel transitions,
+              // we do not continue pre-warming.
+            ]
+          : [
+              'Loading...',
+              'Suspend! [Sibling: Loading...]',
+              'Final',
+              'Suspend! [Sibling: Final]',
+            ]),
+      ]);
+      expect(root).toMatchRenderedOutput(null);
+
+      // The initial sibling loads, we're unblocked and commit.
+      await act(() => {
+        resolveText('Sibling: Loading...');
+      });
+      assertLog([
+        'Loading...',
+        'Sibling: Loading...',
+        'Final',
+        'Suspend! [Sibling: Final]',
+      ]);
+      expect(root).toMatchRenderedOutput('Loading... Sibling: Loading...');
+
+      // Now unblock the final sibling.
+      await act(() => {
+        resolveText('Sibling: Final');
+      });
+      assertLog(['Final', 'Sibling: Final']);
+      expect(root).toMatchRenderedOutput('Final Sibling: Final');
+    },
+  );
+
   it(
     'if a suspended render spawns a deferred task, we can switch to the ' +
       'deferred task without finishing the original one (no Suspense boundary, ' +
@@ -462,9 +631,12 @@ describe('ReactDeferredValue', () => {
         // The initial value suspended, so we attempt the final value, which
         // also suspends.
         'Suspend! [Final]',
-        // pre-warming
-        'Suspend! [Loading...]',
-        'Suspend! [Final]',
+        ...(gate('enableParallelTransitions')
+          ? [
+              // With parallel transitions,
+              // we do not continue pre-warming.
+            ]
+          : ['Suspend! [Loading...]', 'Suspend! [Final]']),
       ]);
       expect(root).toMatchRenderedOutput(null);
 
@@ -539,9 +711,12 @@ describe('ReactDeferredValue', () => {
         // The initial value suspended, so we attempt the final value, which
         // also suspends.
         'Suspend! [Final]',
-        // pre-warming
-        'Suspend! [Loading...]',
-        'Suspend! [Final]',
+        ...(gate('enableParallelTransitions')
+          ? [
+              // With parallel transitions,
+              // we do not continue pre-warming.
+            ]
+          : ['Suspend! [Loading...]', 'Suspend! [Final]']),
       ]);
       expect(root).toMatchRenderedOutput(null);
 
diff --git a/packages/react-reconciler/src/__tests__/ReactTransition-test.js b/packages/react-reconciler/src/__tests__/ReactTransition-test.js
index d3ad2e613857..7a962018067a 100644
--- a/packages/react-reconciler/src/__tests__/ReactTransition-test.js
+++ b/packages/react-reconciler/src/__tests__/ReactTransition-test.js
@@ -209,6 +209,319 @@ describe('ReactTransition', () => {
     expect(root).toMatchRenderedOutput('Async');
   });
 
+  // @gate enableLegacyCache
+  it('when multiple transitions update different queues, they entangle', async () => {
+    let setA;
+    let startTransitionA;
+    let setB;
+    let startTransitionB;
+    function A() {
+      const [a, _setA] = useState(0);
+      const [isPending, _startTransitionA] = useTransition();
+      setA = _setA;
+      startTransitionA = _startTransitionA;
+
+      return (
+        <span>
+          {isPending && (
+            <span>
+              <Text text="Pending A..." />
+            </span>
+          )}
+          <AsyncText text={`A: ${a}`} />
+        </span>
+      );
+    }
+
+    function B() {
+      const [b, _setB] = useState(0);
+      const [isPending, _startTransitionB] = useTransition();
+      setB = _setB;
+      startTransitionB = _startTransitionB;
+
+      return (
+        <span>
+          {isPending && (
+            <span>
+              <Text text="Pending B..." />
+            </span>
+          )}
+          <AsyncText text={`B: ${b}`} />
+        </span>
+      );
+    }
+    function App() {
+      return (
+        <>
+          <Suspense fallback={<span>Loading A</span>}>
+            <A />
+          </Suspense>
+          <Suspense fallback={<span>Loading B</span>}>
+            <B />
+          </Suspense>
+        </>
+      );
+    }
+
+    // Initial render
+    const root = ReactNoop.createRoot();
+    await act(() => {
+      root.render(<App />);
+    });
+    assertLog([
+      'Suspend! [A: 0]',
+      'Suspend! [B: 0]',
+      'Suspend! [A: 0]',
+      'Suspend! [B: 0]',
+    ]);
+    expect(root).toMatchRenderedOutput(
+      <>
+        <span>Loading A</span>
+        <span>Loading B</span>
+      </>,
+    );
+
+    // Resolve
+    await act(() => {
+      resolveText('A: 0');
+      resolveText('B: 0');
+    });
+    assertLog(['A: 0', 'B: 0']);
+    expect(root).toMatchRenderedOutput(
+      <>
+        <span>A: 0</span>
+        <span>B: 0</span>
+      </>,
+    );
+
+    // Start transitioning A
+    await act(() => {
+      startTransitionA(() => {
+        setA(1);
+      });
+    });
+    assertLog(['Pending A...', 'A: 0', 'Suspend! [A: 1]']);
+    expect(root).toMatchRenderedOutput(
+      <>
+        <span>
+          <span>Pending A...</span>A: 0
+        </span>
+        <span>B: 0</span>
+      </>,
+    );
+
+    // Start transitioning B
+    await act(() => {
+      startTransitionB(() => {
+        setB(1);
+      });
+    });
+    assertLog(['Pending B...', 'B: 0', 'Suspend! [A: 1]', 'Suspend! [B: 1]']);
+    expect(root).toMatchRenderedOutput(
+      <>
+        <span>
+          <span>Pending A...</span>A: 0
+        </span>
+        <span>
+          <span>Pending B...</span>B: 0
+        </span>
+      </>,
+    );
+
+    // Resolve B
+    await act(() => {
+      resolveText('B: 1');
+    });
+    assertLog(
+      gate('enableParallelTransitions')
+        ? ['B: 1', 'Suspend! [A: 1]']
+        : ['Suspend! [A: 1]', 'B: 1'],
+    );
+    expect(root).toMatchRenderedOutput(
+      gate('enableParallelTransitions') ? (
+        <>
+          <span>
+            <span>Pending A...</span>A: 0
+          </span>
+          <span>B: 1</span>
+        </>
+      ) : (
+        <>
+          <span>
+            <span>Pending A...</span>A: 0
+          </span>
+          <span>
+            <span>Pending B...</span>B: 0
+          </span>
+        </>
+      ),
+    );
+
+    // Resolve A
+    await act(() => {
+      resolveText('A: 1');
+    });
+    assertLog(gate('enableParallelTransitions') ? ['A: 1'] : ['A: 1', 'B: 1']);
+    expect(root).toMatchRenderedOutput(
+      <>
+        <span>A: 1</span>
+        <span>B: 1</span>
+      </>,
+    );
+  });
+
+  // @gate enableLegacyCache
+  it('when multiple transitions update different queues, but suspend the same boundary, they do entangle', async () => {
+    let setA;
+    let startTransitionA;
+    let setB;
+    let startTransitionB;
+    function A() {
+      const [a, _setA] = useState(0);
+      const [isPending, _startTransitionA] = useTransition();
+      setA = _setA;
+      startTransitionA = _startTransitionA;
+
+      return (
+        <span>
+          {isPending && (
+            <span>
+              <Text text="Pending A..." />
+            </span>
+          )}
+          <AsyncText text={`A: ${a}`} />
+        </span>
+      );
+    }
+
+    function B() {
+      const [b, _setB] = useState(0);
+      const [isPending, _startTransitionB] = useTransition();
+      setB = _setB;
+      startTransitionB = _startTransitionB;
+
+      return (
+        <span>
+          {isPending && (
+            <span>
+              <Text text="Pending B..." />
+            </span>
+          )}
+          <AsyncText text={`B: ${b}`} />
+        </span>
+      );
+    }
+    function App() {
+      return (
+        <Suspense fallback={<span>Loading...</span>}>
+          <A />
+          <B />
+        </Suspense>
+      );
+    }
+
+    // Initial render
+    const root = ReactNoop.createRoot();
+    await act(() => {
+      root.render(<App />);
+    });
+    assertLog([
+      'Suspend! [A: 0]',
+      // pre-warming
+      'Suspend! [A: 0]',
+      'Suspend! [B: 0]',
+    ]);
+    expect(root).toMatchRenderedOutput(<span>Loading...</span>);
+
+    // Resolve
+    await act(() => {
+      resolveText('A: 0');
+      resolveText('B: 0');
+    });
+    assertLog(['A: 0', 'B: 0']);
+    expect(root).toMatchRenderedOutput(
+      <>
+        <span>A: 0</span>
+        <span>B: 0</span>
+      </>,
+    );
+
+    // Start transitioning A
+    await act(() => {
+      startTransitionA(() => {
+        setA(1);
+      });
+    });
+    assertLog(['Pending A...', 'A: 0', 'Suspend! [A: 1]']);
+    expect(root).toMatchRenderedOutput(
+      <>
+        <span>
+          <span>Pending A...</span>A: 0
+        </span>
+        <span>B: 0</span>
+      </>,
+    );
+
+    // Start transitioning B
+    await act(() => {
+      startTransitionB(() => {
+        setB(1);
+      });
+    });
+    assertLog(['Pending B...', 'B: 0', 'Suspend! [A: 1]', 'Suspend! [B: 1]']);
+    expect(root).toMatchRenderedOutput(
+      <>
+        <span>
+          <span>Pending A...</span>A: 0
+        </span>
+        <span>
+          <span>Pending B...</span>B: 0
+        </span>
+      </>,
+    );
+
+    // Resolve B
+    await act(() => {
+      resolveText('B: 1');
+    });
+    assertLog(
+      gate('enableParallelTransitions')
+        ? ['B: 1', 'Suspend! [A: 1]']
+        : ['Suspend! [A: 1]', 'B: 1'],
+    );
+    expect(root).toMatchRenderedOutput(
+      gate('enableParallelTransitions') ? (
+        <>
+          <span>
+            <span>Pending A...</span>A: 0
+          </span>
+          <span>B: 1</span>
+        </>
+      ) : (
+        <>
+          <span>
+            <span>Pending A...</span>A: 0
+          </span>
+          <span>
+            <span>Pending B...</span>B: 0
+          </span>
+        </>
+      ),
+    );
+
+    // Resolve A
+    await act(() => {
+      resolveText('A: 1');
+    });
+    assertLog(gate('enableParallelTransitions') ? ['A: 1'] : ['A: 1', 'B: 1']);
+    expect(root).toMatchRenderedOutput(
+      <>
+        <span>A: 1</span>
+        <span>B: 1</span>
+      </>,
+    );
+  });
+
   // @gate enableLegacyCache
   it(
     'when multiple transitions update the same queue, only the most recent ' +
diff --git a/packages/shared/ReactFeatureFlags.js b/packages/shared/ReactFeatureFlags.js
index 113370d1eb79..affa741aa9e4 100644
--- a/packages/shared/ReactFeatureFlags.js
+++ b/packages/shared/ReactFeatureFlags.js
@@ -215,6 +215,9 @@ export const disableInputAttributeSyncing: boolean = false;
 // Disables children for <textarea> elements
 export const disableTextareaChildren: boolean = false;
 
+// Disables children for <textarea> elements
+export const enableParallelTransitions: boolean = true;
+
 // -----------------------------------------------------------------------------
 // Debugging and DevTools
 // -----------------------------------------------------------------------------
diff --git a/packages/shared/forks/ReactFeatureFlags.native-fb.js b/packages/shared/forks/ReactFeatureFlags.native-fb.js
index 48481ef3e28b..1ee20a3a7a99 100644
--- a/packages/shared/forks/ReactFeatureFlags.native-fb.js
+++ b/packages/shared/forks/ReactFeatureFlags.native-fb.js
@@ -83,6 +83,7 @@ export const enablePerformanceIssueReporting: boolean =
   enableComponentPerformanceTrack;
 export const enableInternalInstanceMap: boolean = false;
 export const enableOptimisticKey: boolean = false;
+export const enableParallelTransitions: boolean = false;
 
 // Flow magic to verify the exports of this file match the original version.
 ((((null: any): ExportsType): FeatureFlagsType): ExportsType);
diff --git a/packages/shared/forks/ReactFeatureFlags.native-oss.js b/packages/shared/forks/ReactFeatureFlags.native-oss.js
index 93f2f1d478cb..4b3d563c2348 100644
--- a/packages/shared/forks/ReactFeatureFlags.native-oss.js
+++ b/packages/shared/forks/ReactFeatureFlags.native-oss.js
@@ -83,6 +83,7 @@ export const enableProfilerTimer: boolean = __PROFILE__;
 export const enableProfilerCommitHooks: boolean = __PROFILE__;
 export const enableProfilerNestedUpdatePhase: boolean = __PROFILE__;
 export const enableUpdaterTracking: boolean = __PROFILE__;
+export const enableParallelTransitions: boolean = false;
 
 // Flow magic to verify the exports of this file match the original version.
 ((((null: any): ExportsType): FeatureFlagsType): ExportsType);
diff --git a/packages/shared/forks/ReactFeatureFlags.test-renderer.js b/packages/shared/forks/ReactFeatureFlags.test-renderer.js
index ed78bd454b26..c8831ad63bd5 100644
--- a/packages/shared/forks/ReactFeatureFlags.test-renderer.js
+++ b/packages/shared/forks/ReactFeatureFlags.test-renderer.js
@@ -92,6 +92,7 @@ export const enableReactTestRendererWarning: boolean = true;
 export const enableObjectFiber: boolean = false;
 
 export const enableOptimisticKey: boolean = false;
+export const enableParallelTransitions: boolean = false;
 
 // Flow magic to verify the exports of this file match the original version.
 ((((null: any): ExportsType): FeatureFlagsType): ExportsType);
diff --git a/packages/shared/forks/ReactFeatureFlags.test-renderer.native-fb.js b/packages/shared/forks/ReactFeatureFlags.test-renderer.native-fb.js
index e9003ece4397..318ba28c57b6 100644
--- a/packages/shared/forks/ReactFeatureFlags.test-renderer.native-fb.js
+++ b/packages/shared/forks/ReactFeatureFlags.test-renderer.native-fb.js
@@ -69,6 +69,7 @@ export const enableFragmentRefsInstanceHandles = false;
 export const enableFragmentRefsTextNodes = false;
 export const ownerStackLimit = 1e4;
 export const enableOptimisticKey = false;
+export const enableParallelTransitions = false;
 
 // Flow magic to verify the exports of this file match the original version.
 ((((null: any): ExportsType): FeatureFlagsType): ExportsType);
diff --git a/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js b/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js
index 675db5ba1c73..df15a19d15d8 100644
--- a/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js
+++ b/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js
@@ -84,6 +84,7 @@ export const ownerStackLimit = 1e4;
 export const enableInternalInstanceMap: boolean = false;
 
 export const enableOptimisticKey: boolean = false;
+export const enableParallelTransitions: boolean = false;
 
 // Flow magic to verify the exports of this file match the original version.
 ((((null: any): ExportsType): FeatureFlagsType): ExportsType);
diff --git a/packages/shared/forks/ReactFeatureFlags.www-dynamic.js b/packages/shared/forks/ReactFeatureFlags.www-dynamic.js
index 03740acdb4cd..8bc9fb595348 100644
--- a/packages/shared/forks/ReactFeatureFlags.www-dynamic.js
+++ b/packages/shared/forks/ReactFeatureFlags.www-dynamic.js
@@ -37,6 +37,7 @@ export const enableFragmentRefsScrollIntoView: boolean = __VARIANT__;
 export const enableFragmentRefsTextNodes: boolean = __VARIANT__;
 export const enableInternalInstanceMap: boolean = __VARIANT__;
 export const enableTrustedTypesIntegration: boolean = __VARIANT__;
+export const enableParallelTransitions: boolean = __VARIANT__;
 
 // TODO: These flags are hard-coded to the default values used in open source.
 // Update the tests so that they pass in either mode, then set these
diff --git a/packages/shared/forks/ReactFeatureFlags.www.js b/packages/shared/forks/ReactFeatureFlags.www.js
index 3f8838221c7e..922386366873 100644
--- a/packages/shared/forks/ReactFeatureFlags.www.js
+++ b/packages/shared/forks/ReactFeatureFlags.www.js
@@ -34,6 +34,7 @@ export const {
   enableFragmentRefsScrollIntoView,
   enableFragmentRefsTextNodes,
   enableInternalInstanceMap,
+  enableParallelTransitions,
 } = dynamicFeatureFlags;
 
 // On WWW, __EXPERIMENTAL__ is used for a new modern build.

From 087a34696f1eb484157b19aee1648bcbce51de64 Mon Sep 17 00:00:00 2001
From: Ricky <rickhanlonii@gmail.com>
Date: Wed, 4 Feb 2026 14:37:45 -0500
Subject: [PATCH 6/7] [test] add activity test with gSBU and
 enableViewTransition bugfix (#35555)

Related to https://github.com/facebook/react/pull/35548,
`enableViewTransition` fixes a bug where `getSnapshotBeforeUpdate` was
running in hidden trees when it shouldn't (`componentWillUpdate` won't
run for hidden updates, and when it becomes visible it will be called
with `componentWillMount`).
---
 .../src/__tests__/Activity-test.js            | 81 +++++++++++++++++++
 1 file changed, 81 insertions(+)

diff --git a/packages/react-reconciler/src/__tests__/Activity-test.js b/packages/react-reconciler/src/__tests__/Activity-test.js
index a27e62e585fb..9abebad1dd09 100644
--- a/packages/react-reconciler/src/__tests__/Activity-test.js
+++ b/packages/react-reconciler/src/__tests__/Activity-test.js
@@ -1527,6 +1527,87 @@ describe('Activity', () => {
     expect(root).toMatchRenderedOutput(<span prop={2} />);
   });
 
+  // @gate enableActivity
+  it('getSnapshotBeforeUpdate does not run in hidden trees', async () => {
+    let setState;
+
+    class Child extends React.Component {
+      getSnapshotBeforeUpdate(prevProps) {
+        const snapshot = `snapshot-${prevProps.value}-to-${this.props.value}`;
+        Scheduler.log(`getSnapshotBeforeUpdate: ${snapshot}`);
+        return snapshot;
+      }
+      componentDidUpdate(prevProps, prevState, snapshot) {
+        Scheduler.log(`componentDidUpdate: ${snapshot}`);
+      }
+      componentDidMount() {
+        Scheduler.log('componentDidMount');
+      }
+      componentWillUnmount() {
+        Scheduler.log('componentWillUnmount');
+      }
+      render() {
+        Scheduler.log(`render: ${this.props.value}`);
+        return <span prop={this.props.value} />;
+      }
+    }
+
+    function Wrapper({show}) {
+      const [value, _setState] = useState(1);
+      setState = _setState;
+      return (
+        <Activity mode={show ? 'visible' : 'hidden'}>
+          <Child value={value} />
+        </Activity>
+      );
+    }
+
+    const root = ReactNoop.createRoot();
+
+    // Initial render
+    await act(() => {
+      root.render(<Wrapper show={true} />);
+    });
+    assertLog(['render: 1', 'componentDidMount']);
+
+    // Hide the Activity
+    await act(() => {
+      root.render(<Wrapper show={false} />);
+    });
+    assertLog([
+      'componentWillUnmount',
+      'render: 1',
+      // Bugfix: snapshots for hidden trees should not need to be read.
+      ...(gate('enableViewTransition')
+        ? []
+        : ['getSnapshotBeforeUpdate: snapshot-1-to-1']),
+    ]);
+
+    // Trigger an update while hidden by calling setState
+    await act(() => {
+      setState(2);
+    });
+    assertLog([
+      'render: 2',
+      ...(gate('enableViewTransition')
+        ? []
+        : ['getSnapshotBeforeUpdate: snapshot-1-to-2']),
+    ]);
+
+    // This is treated as a new mount so the snapshot also shouldn't be read.
+    await act(() => {
+      root.render(<Wrapper show={true} />);
+    });
+    assertLog([
+      'render: 2',
+      ...(gate('enableViewTransition')
+        ? []
+        : ['getSnapshotBeforeUpdate: snapshot-2-to-2']),
+      'componentDidMount',
+    ]);
+  });
+
+  // @gate enableActivity
   it('warns if you pass a hidden prop', async () => {
     function App() {
       return (

From 3aaab92a265ebeb43b15e7c30c2f1dfb9fcd5961 Mon Sep 17 00:00:00 2001
From: Ricky <rickhanlonii@gmail.com>
Date: Wed, 4 Feb 2026 15:04:57 -0500
Subject: [PATCH 7/7] [flags] add enableEffectEventMutationPhase (#35548)

Small optimization for useEffectEvent. Not sure we even need a flag for
it, but it will be a nice killswitch.

As an added benefit, it fixes a bug when `enableViewTransition` is on,
where we were not updating the useEffectEvent callback when a tree went
from hidden to visible.
---
 .../src/ReactFiberCommitWork.js               |  21 +-
 .../react-reconciler/src/ReactFiberFlags.js   |  14 +-
 .../src/__tests__/useEffectEvent-test.js      | 416 ++++++++++++++++++
 packages/shared/ReactFeatureFlags.js          |   4 +
 .../ReactFeatureFlags.native-fb-dynamic.js    |   1 +
 .../forks/ReactFeatureFlags.native-fb.js      |   1 +
 .../forks/ReactFeatureFlags.native-oss.js     |   1 +
 .../forks/ReactFeatureFlags.test-renderer.js  |   1 +
 ...actFeatureFlags.test-renderer.native-fb.js |   1 +
 .../ReactFeatureFlags.test-renderer.www.js    |   1 +
 .../forks/ReactFeatureFlags.www-dynamic.js    |   2 +
 .../shared/forks/ReactFeatureFlags.www.js     |   1 +
 12 files changed, 458 insertions(+), 6 deletions(-)

diff --git a/packages/react-reconciler/src/ReactFiberCommitWork.js b/packages/react-reconciler/src/ReactFiberCommitWork.js
index 43db744007d4..08882a04766c 100644
--- a/packages/react-reconciler/src/ReactFiberCommitWork.js
+++ b/packages/react-reconciler/src/ReactFiberCommitWork.js
@@ -47,6 +47,7 @@ import type {ViewTransitionState} from './ReactFiberViewTransitionComponent';
 import {
   alwaysThrottleRetries,
   enableCreateEventHandleAPI,
+  enableEffectEventMutationPhase,
   enableHiddenSubtreeInsertionEffectCleanup,
   enableProfilerTimer,
   enableProfilerCommitHooks,
@@ -499,7 +500,7 @@ function commitBeforeMutationEffectsOnFiber(
     case FunctionComponent:
     case ForwardRef:
     case SimpleMemoComponent: {
-      if ((flags & Update) !== NoFlags) {
+      if (!enableEffectEventMutationPhase && (flags & Update) !== NoFlags) {
         const updateQueue: FunctionComponentUpdateQueue | null =
           (finishedWork.updateQueue: any);
         const eventPayloads = updateQueue !== null ? updateQueue.events : null;
@@ -2042,6 +2043,24 @@ function commitMutationEffectsOnFiber(
     case ForwardRef:
     case MemoComponent:
     case SimpleMemoComponent: {
+      // Mutate event effect callbacks on the way down, before mutation effects.
+      // This ensures that parent event effects are mutated before child effects.
+      // This isn't a supported use case, so we can re-consider it,
+      // but this was the behavior we originally shipped.
+      if (enableEffectEventMutationPhase) {
+        if (flags & Update) {
+          const updateQueue: FunctionComponentUpdateQueue | null =
+            (finishedWork.updateQueue: any);
+          const eventPayloads =
+            updateQueue !== null ? updateQueue.events : null;
+          if (eventPayloads !== null) {
+            for (let ii = 0; ii < eventPayloads.length; ii++) {
+              const {ref, nextImpl} = eventPayloads[ii];
+              ref.impl = nextImpl;
+            }
+          }
+        }
+      }
       recursivelyTraverseMutationEffects(root, finishedWork, lanes);
       commitReconciliationEffects(finishedWork, lanes);
 
diff --git a/packages/react-reconciler/src/ReactFiberFlags.js b/packages/react-reconciler/src/ReactFiberFlags.js
index 2d8d3f7fd16c..9f85897fb05c 100644
--- a/packages/react-reconciler/src/ReactFiberFlags.js
+++ b/packages/react-reconciler/src/ReactFiberFlags.js
@@ -7,7 +7,10 @@
  * @flow
  */
 
-import {enableCreateEventHandleAPI} from 'shared/ReactFeatureFlags';
+import {
+  enableCreateEventHandleAPI,
+  enableEffectEventMutationPhase,
+} from 'shared/ReactFeatureFlags';
 
 export type Flags = number;
 
@@ -99,10 +102,11 @@ export const BeforeMutationMask: number =
       // TODO: Only need to visit Deletions during BeforeMutation phase if an
       // element is focused.
       Update | ChildDeletion | Visibility
-    : // TODO: The useEffectEvent hook uses the snapshot phase for clean up but it
-      // really should use the mutation phase for this or at least schedule an
-      // explicit Snapshot phase flag for this.
-      Update);
+    : // useEffectEvent uses the snapshot phase,
+      // but we're moving it to the mutation phase.
+      enableEffectEventMutationPhase
+      ? 0
+      : Update);
 
 // For View Transition support we use the snapshot phase to scan the tree for potentially
 // affected ViewTransition components.
diff --git a/packages/react-reconciler/src/__tests__/useEffectEvent-test.js b/packages/react-reconciler/src/__tests__/useEffectEvent-test.js
index 2b5af2206b9b..b120adf61159 100644
--- a/packages/react-reconciler/src/__tests__/useEffectEvent-test.js
+++ b/packages/react-reconciler/src/__tests__/useEffectEvent-test.js
@@ -27,6 +27,7 @@ describe('useEffectEvent', () => {
   let waitForAll;
   let assertLog;
   let waitForThrow;
+  let waitFor;
 
   beforeEach(() => {
     React = require('react');
@@ -46,6 +47,7 @@ describe('useEffectEvent', () => {
     waitForAll = InternalTestUtils.waitForAll;
     assertLog = InternalTestUtils.assertLog;
     waitForThrow = InternalTestUtils.waitForThrow;
+    waitFor = InternalTestUtils.waitFor;
   });
 
   function Text(props) {
@@ -595,6 +597,358 @@ describe('useEffectEvent', () => {
     assertLog(['Effect value: 2', 'Event value: 2']);
   });
 
+  it('fires all (interleaved) effects with useEffectEvent in correct order', async () => {
+    function CounterA({count}) {
+      const onEvent = useEffectEvent(() => {
+        return `A ${count}`;
+      });
+
+      useInsertionEffect(() => {
+        // Call the event function to verify it sees the latest value
+        Scheduler.log(`Parent Insertion Create: ${onEvent()}`);
+        return () => {
+          Scheduler.log(`Parent Insertion Create: ${onEvent()}`);
+        };
+      });
+
+      useLayoutEffect(() => {
+        Scheduler.log(`Parent Layout Create: ${onEvent()}`);
+        return () => {
+          Scheduler.log(`Parent Layout Cleanup: ${onEvent()}`);
+        };
+      });
+
+      useEffect(() => {
+        Scheduler.log(`Parent Passive Create: ${onEvent()}`);
+        return () => {
+          Scheduler.log(`Parent Passive Destroy ${onEvent()}`);
+        };
+      });
+
+      // this breaks the rules, but ensures the ordering is correct.
+      return <CounterB count={count} onEventParent={onEvent} />;
+    }
+
+    function CounterB({count, onEventParent}) {
+      const onEvent = useEffectEvent(() => {
+        return `${onEventParent()} B ${count}`;
+      });
+
+      useInsertionEffect(() => {
+        Scheduler.log(`Child Insertion Create ${onEvent()}`);
+        return () => {
+          Scheduler.log(`Child Insertion Destroy ${onEvent()}`);
+        };
+      });
+
+      useLayoutEffect(() => {
+        Scheduler.log(`Child Layout Create ${onEvent()}`);
+        return () => {
+          Scheduler.log(`Child Layout Destroy ${onEvent()}`);
+        };
+      });
+
+      useEffect(() => {
+        Scheduler.log(`Child Passive Create ${onEvent()}`);
+        return () => {
+          Scheduler.log(`Child Passive Destroy ${onEvent()}`);
+        };
+      });
+
+      return null;
+    }
+
+    await act(async () => {
+      ReactNoop.render(<CounterA count={1} />);
+    });
+
+    assertLog([
+      'Child Insertion Create A 1 B 1',
+      'Parent Insertion Create: A 1',
+      'Child Layout Create A 1 B 1',
+      'Parent Layout Create: A 1',
+      'Child Passive Create A 1 B 1',
+      'Parent Passive Create: A 1',
+    ]);
+
+    await act(async () => {
+      ReactNoop.render(<CounterA count={2} />);
+    });
+
+    assertLog([
+      'Child Insertion Destroy A 2 B 2',
+      'Child Insertion Create A 2 B 2',
+      'Child Layout Destroy A 2 B 2',
+      'Parent Insertion Create: A 2',
+      'Parent Insertion Create: A 2',
+      'Parent Layout Cleanup: A 2',
+      'Child Layout Create A 2 B 2',
+      'Parent Layout Create: A 2',
+      'Child Passive Destroy A 2 B 2',
+      'Parent Passive Destroy A 2',
+      'Child Passive Create A 2 B 2',
+      'Parent Passive Create: A 2',
+    ]);
+
+    // Unmount everything
+    await act(async () => {
+      ReactNoop.render(null);
+    });
+
+    assertLog([
+      'Parent Insertion Create: A 2',
+      'Parent Layout Cleanup: A 2',
+      'Child Insertion Destroy A 2 B 2',
+      'Child Layout Destroy A 2 B 2',
+      'Parent Passive Destroy A 2',
+      'Child Passive Destroy A 2 B 2',
+    ]);
+  });
+
+  it('correctly mutates effect event with Activity', async () => {
+    let setState;
+    let setChildState;
+    function CounterA({count, hideChild}) {
+      const [state, _setState] = useState(1);
+      setState = _setState;
+      const onEvent = useEffectEvent(() => {
+        return `A ${count} ${state}`;
+      });
+
+      useInsertionEffect(() => {
+        // Call the event function to verify it sees the latest value
+        Scheduler.log(`Parent Insertion Create: ${onEvent()}`);
+        return () => {
+          Scheduler.log(`Parent Insertion Create: ${onEvent()}`);
+        };
+      });
+
+      useLayoutEffect(() => {
+        Scheduler.log(`Parent Layout Create: ${onEvent()}`);
+        return () => {
+          Scheduler.log(`Parent Layout Cleanup: ${onEvent()}`);
+        };
+      });
+
+      // this breaks the rules, but ensures the ordering is correct.
+      return (
+        <React.Activity mode={hideChild ? 'hidden' : 'visible'}>
+          <CounterB count={count} state={state} onEventParent={onEvent} />
+        </React.Activity>
+      );
+    }
+
+    function CounterB({count, state, onEventParent}) {
+      const [childState, _setChildState] = useState(1);
+      setChildState = _setChildState;
+      const onEvent = useEffectEvent(() => {
+        return `${onEventParent()} B ${count} ${state} ${childState}`;
+      });
+
+      useInsertionEffect(() => {
+        Scheduler.log(`Child Insertion Create ${onEvent()}`);
+        return () => {
+          Scheduler.log(`Child Insertion Destroy ${onEvent()}`);
+        };
+      });
+
+      useLayoutEffect(() => {
+        Scheduler.log(`Child Layout Create ${onEvent()}`);
+        return () => {
+          Scheduler.log(`Child Layout Destroy ${onEvent()}`);
+        };
+      });
+
+      useEffect(() => {
+        Scheduler.log(`Child Passive Create ${onEvent()}`);
+        return () => {
+          Scheduler.log(`Child Passive Destroy ${onEvent()}`);
+        };
+      });
+
+      return null;
+    }
+
+    await act(async () => {
+      ReactNoop.render(<CounterA count={1} hideChild={true} />);
+      await waitFor([
+        'Parent Insertion Create: A 1 1',
+        'Parent Layout Create: A 1 1',
+        'Child Insertion Create A 1 1 B 1 1 1',
+      ]);
+    });
+
+    assertLog([]);
+
+    await act(async () => {
+      ReactNoop.render(<CounterA count={2} hideChild={true} />);
+
+      await waitFor([
+        'Parent Insertion Create: A 2 1',
+        'Parent Insertion Create: A 2 1',
+        'Parent Layout Cleanup: A 2 1',
+        'Parent Layout Create: A 2 1',
+        ...(gate('enableViewTransition') &&
+        !gate('enableEffectEventMutationPhase')
+          ? [
+              'Child Insertion Destroy A 2 1 B 1 1 1',
+              'Child Insertion Create A 2 1 B 1 1 1',
+            ]
+          : [
+              'Child Insertion Destroy A 2 1 B 2 1 1',
+              'Child Insertion Create A 2 1 B 2 1 1',
+            ]),
+      ]);
+    });
+
+    assertLog([]);
+
+    await act(async () => {
+      setState(2);
+
+      await waitFor([
+        'Parent Insertion Create: A 2 2',
+        'Parent Insertion Create: A 2 2',
+        'Parent Layout Cleanup: A 2 2',
+        'Parent Layout Create: A 2 2',
+        ...(gate('enableViewTransition') &&
+        !gate('enableEffectEventMutationPhase')
+          ? [
+              'Child Insertion Destroy A 2 2 B 1 1 1',
+              'Child Insertion Create A 2 2 B 1 1 1',
+            ]
+          : [
+              'Child Insertion Destroy A 2 2 B 2 2 1',
+              'Child Insertion Create A 2 2 B 2 2 1',
+            ]),
+      ]);
+    });
+
+    assertLog([]);
+
+    await act(async () => {
+      setChildState(2);
+
+      await waitFor(
+        gate('enableViewTransition') && !gate('enableEffectEventMutationPhase')
+          ? [
+              'Child Insertion Destroy A 2 2 B 1 1 1',
+              'Child Insertion Create A 2 2 B 1 1 1',
+            ]
+          : [
+              'Child Insertion Destroy A 2 2 B 2 2 2',
+              'Child Insertion Create A 2 2 B 2 2 2',
+            ],
+      );
+    });
+
+    assertLog([]);
+
+    await act(async () => {
+      ReactNoop.render(<CounterA count={3} hideChild={true} />);
+
+      await waitFor([
+        'Parent Insertion Create: A 3 2',
+        'Parent Insertion Create: A 3 2',
+        'Parent Layout Cleanup: A 3 2',
+        'Parent Layout Create: A 3 2',
+      ]);
+    });
+
+    assertLog(
+      gate('enableViewTransition') && !gate('enableEffectEventMutationPhase')
+        ? [
+            'Child Insertion Destroy A 3 2 B 1 1 1',
+            'Child Insertion Create A 3 2 B 1 1 1',
+          ]
+        : [
+            'Child Insertion Destroy A 3 2 B 3 2 2',
+            'Child Insertion Create A 3 2 B 3 2 2',
+          ],
+    );
+
+    await act(async () => {
+      ReactNoop.render(<CounterA count={3} hideChild={false} />);
+
+      await waitFor([
+        ...(gate('enableViewTransition') &&
+        !gate('enableEffectEventMutationPhase')
+          ? [
+              'Child Insertion Destroy A 3 2 B 1 1 1',
+              'Child Insertion Create A 3 2 B 1 1 1',
+            ]
+          : [
+              'Child Insertion Destroy A 3 2 B 3 2 2',
+              'Child Insertion Create A 3 2 B 3 2 2',
+            ]),
+        'Parent Insertion Create: A 3 2',
+        'Parent Insertion Create: A 3 2',
+        'Parent Layout Cleanup: A 3 2',
+        ...(gate('enableViewTransition') &&
+        !gate('enableEffectEventMutationPhase')
+          ? ['Child Layout Create A 3 2 B 1 1 1']
+          : ['Child Layout Create A 3 2 B 3 2 2']),
+
+        'Parent Layout Create: A 3 2',
+      ]);
+    });
+
+    assertLog(
+      gate('enableViewTransition') && !gate('enableEffectEventMutationPhase')
+        ? ['Child Passive Create A 3 2 B 1 1 1']
+        : ['Child Passive Create A 3 2 B 3 2 2'],
+    );
+
+    await act(async () => {
+      ReactNoop.render(<CounterA count={3} hideChild={true} />);
+
+      await waitFor([
+        ...(gate('enableViewTransition') &&
+        !gate('enableEffectEventMutationPhase')
+          ? ['Child Layout Destroy A 3 2 B 1 1 1']
+          : ['Child Layout Destroy A 3 2 B 3 2 2']),
+        'Parent Insertion Create: A 3 2',
+        'Parent Insertion Create: A 3 2',
+        'Parent Layout Cleanup: A 3 2',
+        'Parent Layout Create: A 3 2',
+        ...(gate('enableViewTransition') &&
+        !gate('enableEffectEventMutationPhase')
+          ? ['Child Passive Destroy A 3 2 B 1 1 1']
+          : ['Child Passive Destroy A 3 2 B 3 2 2']),
+      ]);
+    });
+
+    assertLog(
+      gate('enableViewTransition') && !gate('enableEffectEventMutationPhase')
+        ? [
+            'Child Insertion Destroy A 3 2 B 1 1 1',
+            'Child Insertion Create A 3 2 B 1 1 1',
+          ]
+        : [
+            'Child Insertion Destroy A 3 2 B 3 2 2',
+            'Child Insertion Create A 3 2 B 3 2 2',
+          ],
+    );
+
+    // Unmount everything
+    await act(async () => {
+      ReactNoop.render(null);
+    });
+
+    assertLog([
+      'Parent Insertion Create: A 3 2',
+      'Parent Layout Cleanup: A 3 2',
+      ...(gate('enableHiddenSubtreeInsertionEffectCleanup')
+        ? [
+            gate('enableViewTransition') &&
+            !gate('enableEffectEventMutationPhase')
+              ? 'Child Insertion Destroy A 3 2 B 1 1 1'
+              : 'Child Insertion Destroy A 3 2 B 3 2 2',
+          ]
+        : []),
+    ]);
+  });
+
   it("doesn't provide a stable identity", async () => {
     function Counter({shouldRender, value}) {
       const onClick = useEffectEvent(() => {
@@ -916,4 +1270,66 @@ describe('useEffectEvent', () => {
     logContextValue();
     assertLog(['ContextReader (Effect event): second']);
   });
+
+  // @gate enableActivity
+  it('effect events are fresh inside Activity', async () => {
+    function Child({value}) {
+      const getValue = useEffectEvent(() => {
+        return value;
+      });
+      useInsertionEffect(() => {
+        Scheduler.log('insertion create: ' + getValue());
+        return () => {
+          Scheduler.log('insertion destroy: ' + getValue());
+        };
+      });
+      useLayoutEffect(() => {
+        Scheduler.log('layout create: ' + getValue());
+        return () => {
+          Scheduler.log('layout destroy: ' + getValue());
+        };
+      });
+
+      Scheduler.log('render: ' + value);
+      return null;
+    }
+
+    function App({value, mode}) {
+      return (
+        <React.Activity mode={mode}>
+          <Child value={value} />
+        </React.Activity>
+      );
+    }
+
+    const root = ReactNoop.createRoot();
+
+    // Mount hidden
+    await act(async () => root.render(<App value={1} mode="hidden" />));
+    assertLog(['render: 1', 'insertion create: 1']);
+
+    // Update, still hidden
+    await act(async () => root.render(<App value={2} mode="hidden" />));
+
+    // Bug in enableViewTransition. Insertion and layout see stale closure.
+    assertLog([
+      'render: 2',
+      ...(gate('enableViewTransition') &&
+      !gate('enableEffectEventMutationPhase')
+        ? ['insertion destroy: 1', 'insertion create: 1']
+        : ['insertion destroy: 2', 'insertion create: 2']),
+    ]);
+
+    // Switch to visible
+    await act(async () => root.render(<App value={2} mode="visible" />));
+
+    // Bug in enableViewTransition. Even when switching to visible, sees stale closure.
+    assertLog([
+      'render: 2',
+      ...(gate('enableViewTransition') &&
+      !gate('enableEffectEventMutationPhase')
+        ? ['insertion destroy: 1', 'insertion create: 1', 'layout create: 1']
+        : ['insertion destroy: 2', 'insertion create: 2', 'layout create: 2']),
+    ]);
+  });
 });
diff --git a/packages/shared/ReactFeatureFlags.js b/packages/shared/ReactFeatureFlags.js
index affa741aa9e4..bdeab6aef43e 100644
--- a/packages/shared/ReactFeatureFlags.js
+++ b/packages/shared/ReactFeatureFlags.js
@@ -123,6 +123,10 @@ export const enableFizzExternalRuntime = __EXPERIMENTAL__;
 
 export const alwaysThrottleRetries: boolean = true;
 
+// Gate whether useEffectEvent uses the mutation phase (true) or before-mutation
+// phase (false) for updating event function references.
+export const enableEffectEventMutationPhase: boolean = false;
+
 export const passChildrenWhenCloningPersistedNodes: boolean = false;
 
 export const enableEagerAlternateStateNodeCleanup: boolean = true;
diff --git a/packages/shared/forks/ReactFeatureFlags.native-fb-dynamic.js b/packages/shared/forks/ReactFeatureFlags.native-fb-dynamic.js
index 8082e77e1d67..f8da141560f5 100644
--- a/packages/shared/forks/ReactFeatureFlags.native-fb-dynamic.js
+++ b/packages/shared/forks/ReactFeatureFlags.native-fb-dynamic.js
@@ -25,4 +25,5 @@ export const passChildrenWhenCloningPersistedNodes = __VARIANT__;
 export const enableFragmentRefs = __VARIANT__;
 export const enableFragmentRefsScrollIntoView = __VARIANT__;
 export const enableFragmentRefsInstanceHandles = __VARIANT__;
+export const enableEffectEventMutationPhase = __VARIANT__;
 export const enableFragmentRefsTextNodes = __VARIANT__;
diff --git a/packages/shared/forks/ReactFeatureFlags.native-fb.js b/packages/shared/forks/ReactFeatureFlags.native-fb.js
index 1ee20a3a7a99..eeabe40d33bb 100644
--- a/packages/shared/forks/ReactFeatureFlags.native-fb.js
+++ b/packages/shared/forks/ReactFeatureFlags.native-fb.js
@@ -20,6 +20,7 @@ const dynamicFlags: DynamicExportsType = (dynamicFlagsUntyped: any);
 // the exports object every time a flag is read.
 export const {
   alwaysThrottleRetries,
+  enableEffectEventMutationPhase,
   enableHiddenSubtreeInsertionEffectCleanup,
   enableObjectFiber,
   enableEagerAlternateStateNodeCleanup,
diff --git a/packages/shared/forks/ReactFeatureFlags.native-oss.js b/packages/shared/forks/ReactFeatureFlags.native-oss.js
index 4b3d563c2348..415b479b7c19 100644
--- a/packages/shared/forks/ReactFeatureFlags.native-oss.js
+++ b/packages/shared/forks/ReactFeatureFlags.native-oss.js
@@ -46,6 +46,7 @@ export const enableSchedulingProfiler: boolean =
   !enableComponentPerformanceTrack && __PROFILE__;
 export const enableScopeAPI: boolean = false;
 export const enableEagerAlternateStateNodeCleanup: boolean = true;
+export const enableEffectEventMutationPhase: boolean = false;
 export const enableSuspenseAvoidThisFallback: boolean = false;
 export const enableSuspenseCallback: boolean = false;
 export const enableTaint: boolean = true;
diff --git a/packages/shared/forks/ReactFeatureFlags.test-renderer.js b/packages/shared/forks/ReactFeatureFlags.test-renderer.js
index c8831ad63bd5..5c1ece810825 100644
--- a/packages/shared/forks/ReactFeatureFlags.test-renderer.js
+++ b/packages/shared/forks/ReactFeatureFlags.test-renderer.js
@@ -56,6 +56,7 @@ export const disableClientCache: boolean = true;
 export const enableInfiniteRenderLoopDetection: boolean = false;
 
 export const enableEagerAlternateStateNodeCleanup: boolean = true;
+export const enableEffectEventMutationPhase: boolean = false;
 
 export const enableYieldingBeforePassive: boolean = true;
 
diff --git a/packages/shared/forks/ReactFeatureFlags.test-renderer.native-fb.js b/packages/shared/forks/ReactFeatureFlags.test-renderer.native-fb.js
index 318ba28c57b6..a2e623ff5201 100644
--- a/packages/shared/forks/ReactFeatureFlags.test-renderer.native-fb.js
+++ b/packages/shared/forks/ReactFeatureFlags.test-renderer.native-fb.js
@@ -43,6 +43,7 @@ export const enableComponentPerformanceTrack = false;
 export const enablePerformanceIssueReporting = false;
 export const enableScopeAPI = false;
 export const enableEagerAlternateStateNodeCleanup = true;
+export const enableEffectEventMutationPhase = false;
 export const enableSuspenseAvoidThisFallback = false;
 export const enableSuspenseCallback = false;
 export const enableTaint = true;
diff --git a/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js b/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js
index df15a19d15d8..4751ffb49bc4 100644
--- a/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js
+++ b/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js
@@ -62,6 +62,7 @@ export const disableLegacyMode: boolean = true;
 
 export const enableObjectFiber: boolean = false;
 export const enableEagerAlternateStateNodeCleanup: boolean = true;
+export const enableEffectEventMutationPhase: boolean = false;
 
 export const enableYieldingBeforePassive: boolean = false;
 
diff --git a/packages/shared/forks/ReactFeatureFlags.www-dynamic.js b/packages/shared/forks/ReactFeatureFlags.www-dynamic.js
index 8bc9fb595348..ea0751e87dac 100644
--- a/packages/shared/forks/ReactFeatureFlags.www-dynamic.js
+++ b/packages/shared/forks/ReactFeatureFlags.www-dynamic.js
@@ -39,6 +39,8 @@ export const enableInternalInstanceMap: boolean = __VARIANT__;
 export const enableTrustedTypesIntegration: boolean = __VARIANT__;
 export const enableParallelTransitions: boolean = __VARIANT__;
 
+export const enableEffectEventMutationPhase: boolean = __VARIANT__;
+
 // TODO: These flags are hard-coded to the default values used in open source.
 // Update the tests so that they pass in either mode, then set these
 // to __VARIANT__.
diff --git a/packages/shared/forks/ReactFeatureFlags.www.js b/packages/shared/forks/ReactFeatureFlags.www.js
index 922386366873..d32d8fe08baf 100644
--- a/packages/shared/forks/ReactFeatureFlags.www.js
+++ b/packages/shared/forks/ReactFeatureFlags.www.js
@@ -18,6 +18,7 @@ export const {
   alwaysThrottleRetries,
   disableLegacyContextForFunctionComponents,
   disableSchedulerTimeoutInWorkLoop,
+  enableEffectEventMutationPhase,
   enableHiddenSubtreeInsertionEffectCleanup,
   enableInfiniteRenderLoopDetection,
   enableNoCloningMemoCache,