From 0caa186c5accab2e7de241fce0eed1950746983d Mon Sep 17 00:00:00 2001
From: lms <1359816810@qq.com>
Date: Fri, 3 Apr 2026 15:48:09 +0800
Subject: [PATCH] fix: guard against duplicate Fusebox DevTools dispatcher
 initialization

When using Expo dev client, switching the app from background to foreground
can cause 'TypeError: property is not writable' in setUpFuseboxReactDevToolsDispatcher.

The issue occurs because Metro HMR may invalidate module cache during
foreground transitions, causing setUpDefaultReactNativeEnvironment to be
re-executed and its initialized guard to be reset. This leads to
Object.defineProperty on __FUSEBOX_REACT_DEVTOOLS_DISPATCHER__ running twice.

The fix is to make the property definition idempotent by checking if it
already exists before defining it.
---
 .../setUpFuseboxReactDevToolsDispatcher.js         | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/packages/react-native/src/private/devsupport/rndevtools/setUpFuseboxReactDevToolsDispatcher.js b/packages/react-native/src/private/devsupport/rndevtools/setUpFuseboxReactDevToolsDispatcher.js
index 79f7f4d7688a..e0e2486ac4fe 100644
--- a/packages/react-native/src/private/devsupport/rndevtools/setUpFuseboxReactDevToolsDispatcher.js
+++ b/packages/react-native/src/private/devsupport/rndevtools/setUpFuseboxReactDevToolsDispatcher.js
@@ -105,9 +105,11 @@ class FuseboxReactDevToolsDispatcher {
   }
 }
 
-Object.defineProperty(global, '__FUSEBOX_REACT_DEVTOOLS_DISPATCHER__', {
-  value: FuseboxReactDevToolsDispatcher,
-  configurable: false,
-  enumerable: false,
-  writable: false,
-});
+if (global.__FUSEBOX_REACT_DEVTOOLS_DISPATCHER__ == null) {
+  Object.defineProperty(global, '__FUSEBOX_REACT_DEVTOOLS_DISPATCHER__', {
+    value: FuseboxReactDevToolsDispatcher,
+    configurable: false,
+    enumerable: false,
+    writable: false,
+  });
+}