From b47d78ff5b8f75166f1c1a8a21cad967a20c5f9b Mon Sep 17 00:00:00 2001
From: Gregory Moskaliuk <mosckalyuck@gmail.com>
Date: Sat, 31 Oct 2026 12:58:07 +0100
Subject: [PATCH] Encode fetch responses for DevTools only when a debugger is
 attached

NetworkEventUtil.onDataReceived Base64-encodes every response handled by
a ResponseHandler, which is the blob path fetch uses by default, and
passes it to InspectorNetworkReporter.maybeStoreResponseBody. The
reporter drops the string unless debugging is enabled, so release builds
do this work for every response and throw the result away. Check
isDebuggingEnabled() before encoding.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 .../react/modules/network/NetworkEventUtil.kt | 12 +++---
 .../modules/network/NetworkEventUtilTest.kt   | 38 +++++++++++++++++++
 2 files changed, 45 insertions(+), 5 deletions(-)

diff --git a/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/modules/network/NetworkEventUtil.kt b/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/modules/network/NetworkEventUtil.kt
index 3edd4781341d..73882edd231f 100644
--- a/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/modules/network/NetworkEventUtil.kt
+++ b/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/modules/network/NetworkEventUtil.kt
@@ -139,11 +139,13 @@ internal object NetworkEventUtil {
       data: WritableMap,
       rawData: ByteArray,
   ) {
-    InspectorNetworkReporter.maybeStoreResponseBody(
-        devToolsRequestId,
-        Base64.encodeToString(rawData, Base64.NO_WRAP),
-        true,
-    )
+    if (InspectorNetworkReporter.isDebuggingEnabled()) {
+      InspectorNetworkReporter.maybeStoreResponseBody(
+          devToolsRequestId,
+          Base64.encodeToString(rawData, Base64.NO_WRAP),
+          true,
+      )
+    }
     reactContext?.emitDeviceEvent(
         "didReceiveNetworkData",
         Arguments.createArray().apply {
diff --git a/packages/react-native/ReactAndroid/src/test/java/com/facebook/react/modules/network/NetworkEventUtilTest.kt b/packages/react-native/ReactAndroid/src/test/java/com/facebook/react/modules/network/NetworkEventUtilTest.kt
index 63bdc127bd42..2fc4bc5117d0 100644
--- a/packages/react-native/ReactAndroid/src/test/java/com/facebook/react/modules/network/NetworkEventUtilTest.kt
+++ b/packages/react-native/ReactAndroid/src/test/java/com/facebook/react/modules/network/NetworkEventUtilTest.kt
@@ -9,10 +9,12 @@
 
 package com.facebook.react.modules.network
 
+import android.util.Base64
 import com.facebook.react.bridge.Arguments
 import com.facebook.react.bridge.ReactApplicationContext
 import com.facebook.react.bridge.WritableArray
 import com.facebook.react.bridge.WritableMap
+import com.facebook.react.common.annotations.UnstableReactNativeAPI
 import com.facebook.testutils.shadows.ShadowArguments
 import com.facebook.testutils.shadows.ShadowInspectorNetworkReporter
 import com.facebook.testutils.shadows.ShadowSoLoader
@@ -26,6 +28,7 @@ import org.junit.Before
 import org.junit.Test
 import org.junit.runner.RunWith
 import org.mockito.ArgumentCaptor
+import org.mockito.Mockito.mockStatic
 import org.mockito.kotlin.any
 import org.mockito.kotlin.mock
 import org.mockito.kotlin.never
@@ -173,6 +176,41 @@ class NetworkEventUtilTest {
     assertThat(args.getMap(1)).isEqualTo(data)
   }
 
+  @Test
+  fun testOnDataReceivedMapDoesNotEncodeBodyWithoutDebugger() {
+    mockStatic(Base64::class.java).use { base64 ->
+      NetworkEventUtil.onDataReceived(
+          reactContext,
+          1,
+          "devToolsRequestId",
+          Arguments.createMap(),
+          byteArrayOf(1, 2, 3),
+      )
+
+      base64.verifyNoInteractions()
+    }
+  }
+
+  @OptIn(UnstableReactNativeAPI::class)
+  @Test
+  fun testOnDataReceivedMapStoresEncodedBodyWithDebugger() {
+    mockStatic(InspectorNetworkReporter::class.java).use { reporter ->
+      reporter.`when`<Boolean> { InspectorNetworkReporter.isDebuggingEnabled() }.thenReturn(true)
+
+      NetworkEventUtil.onDataReceived(
+          reactContext,
+          1,
+          "devToolsRequestId",
+          Arguments.createMap(),
+          byteArrayOf(1, 2, 3),
+      )
+
+      reporter.verify {
+        InspectorNetworkReporter.maybeStoreResponseBody("devToolsRequestId", "AQID", true)
+      }
+    }
+  }
+
   @Test
   fun testOnRequestError() {
     val requestId = 1