Integrate CDPAgent into HermesRuntimeTargetDelegate behind flag (#43353)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/43353

## Context

We are migrating to the new Hermes `CDPAgent` and `CDPDebugAPI` APIs in the modern CDP server (previously `HermesCDPHandler`).

## This diff

Integrates `HermesRuntimeAgentDelegateNew` (using the new Hermes `CDPAgent` setup) into `HermesRuntimeTargetDelegate` behind a new feature flag, `inspectorEnableHermesCDPAgent`. This completes the initial integration for all platforms.

Changelog: [Internal]

Reviewed By: motiz88

Differential Revision: D54586162

fbshipit-source-id: 5f26c28af4414d961b1c8c9cb4cd7135bd00b410

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlags.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<a3cb24f7faddd86beb617c8314c1bfed>>
+ * @generated SignedSource<<62ec63a2aebd866803cde1c1ca7d44c6>>
  */
 
 /**
@@ -82,6 +82,12 @@ public object ReactNativeFeatureFlags {
   @JvmStatic
   public fun inspectorEnableCxxInspectorPackagerConnection(): Boolean = accessor.inspectorEnableCxxInspectorPackagerConnection()
 
+  /**
+   * Flag determining if the new Hermes CDPAgent API should be enabled in the modern CDP backend. This flag is global and should not be changed across React Host lifetimes.
+   */
+  @JvmStatic
+  public fun inspectorEnableHermesCDPAgent(): Boolean = accessor.inspectorEnableHermesCDPAgent()
+
   /**
    * Flag determining if the modern CDP backend should be enabled. This flag is global and should not be changed across React Host lifetimes.
    */

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsCxxAccessor.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<8539cf7ba13ab52ca878efd2c4858d7a>>
+ * @generated SignedSource<<c646fd173ad74a352afdd8138f55729e>>
  */
 
 /**
@@ -29,6 +29,7 @@ public class ReactNativeFeatureFlagsCxxAccessor : ReactNativeFeatureFlagsAccesso
   private var enableMountHooksAndroidCache: Boolean? = null
   private var enableSpannableBuildingUnificationCache: Boolean? = null
   private var inspectorEnableCxxInspectorPackagerConnectionCache: Boolean? = null
+  private var inspectorEnableHermesCDPAgentCache: Boolean? = null
   private var inspectorEnableModernCDPRegistryCache: Boolean? = null
   private var skipMountHookNotificationsCache: Boolean? = null
   private var useModernRuntimeSchedulerCache: Boolean? = null
@@ -114,6 +115,15 @@ public class ReactNativeFeatureFlagsCxxAccessor : ReactNativeFeatureFlagsAccesso
     return cached
   }
 
+  override fun inspectorEnableHermesCDPAgent(): Boolean {
+    var cached = inspectorEnableHermesCDPAgentCache
+    if (cached == null) {
+      cached = ReactNativeFeatureFlagsCxxInterop.inspectorEnableHermesCDPAgent()
+      inspectorEnableHermesCDPAgentCache = cached
+    }
+    return cached
+  }
+
   override fun inspectorEnableModernCDPRegistry(): Boolean {
     var cached = inspectorEnableModernCDPRegistryCache
     if (cached == null) {

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsCxxInterop.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<cd7257d4b1414f7aacd02a79b9295a46>>
+ * @generated SignedSource<<9b38540981705aea015b0a5d0ac07c6e>>
  */
 
 /**
@@ -46,6 +46,8 @@ public object ReactNativeFeatureFlagsCxxInterop {
 
   @DoNotStrip @JvmStatic public external fun inspectorEnableCxxInspectorPackagerConnection(): Boolean
 
+  @DoNotStrip @JvmStatic public external fun inspectorEnableHermesCDPAgent(): Boolean
+
   @DoNotStrip @JvmStatic public external fun inspectorEnableModernCDPRegistry(): Boolean
 
   @DoNotStrip @JvmStatic public external fun skipMountHookNotifications(): Boolean

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsDefaults.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<99263973c4a06fdc91e7c9edf4aa4e19>>
+ * @generated SignedSource<<e59e70d753403b168558b0d2b9513b5c>>
  */
 
 /**
@@ -41,6 +41,8 @@ public open class ReactNativeFeatureFlagsDefaults : ReactNativeFeatureFlagsProvi
 
   override fun inspectorEnableCxxInspectorPackagerConnection(): Boolean = false
 
+  override fun inspectorEnableHermesCDPAgent(): Boolean = false
+
   override fun inspectorEnableModernCDPRegistry(): Boolean = false
 
   override fun skipMountHookNotifications(): Boolean = false

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsLocalAccessor.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<e8550b0c2494b223b82e6fab0a827d53>>
+ * @generated SignedSource<<7e3e2b716f8f6caf60b888350041745e>>
  */
 
 /**
@@ -33,6 +33,7 @@ public class ReactNativeFeatureFlagsLocalAccessor : ReactNativeFeatureFlagsAcces
   private var enableMountHooksAndroidCache: Boolean? = null
   private var enableSpannableBuildingUnificationCache: Boolean? = null
   private var inspectorEnableCxxInspectorPackagerConnectionCache: Boolean? = null
+  private var inspectorEnableHermesCDPAgentCache: Boolean? = null
   private var inspectorEnableModernCDPRegistryCache: Boolean? = null
   private var skipMountHookNotificationsCache: Boolean? = null
   private var useModernRuntimeSchedulerCache: Boolean? = null
@@ -127,6 +128,16 @@ public class ReactNativeFeatureFlagsLocalAccessor : ReactNativeFeatureFlagsAcces
     return cached
   }
 
+  override fun inspectorEnableHermesCDPAgent(): Boolean {
+    var cached = inspectorEnableHermesCDPAgentCache
+    if (cached == null) {
+      cached = currentProvider.inspectorEnableHermesCDPAgent()
+      accessedFeatureFlags.add("inspectorEnableHermesCDPAgent")
+      inspectorEnableHermesCDPAgentCache = cached
+    }
+    return cached
+  }
+
   override fun inspectorEnableModernCDPRegistry(): Boolean {
     var cached = inspectorEnableModernCDPRegistryCache
     if (cached == null) {

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsProvider.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<268a87860fea5f281567d2142f90b0d4>>
+ * @generated SignedSource<<d20f46b741dfd156a339fe105fca3cc4>>
  */
 
 /**
@@ -41,6 +41,8 @@ public interface ReactNativeFeatureFlagsProvider {
 
   @DoNotStrip public fun inspectorEnableCxxInspectorPackagerConnection(): Boolean
 
+  @DoNotStrip public fun inspectorEnableHermesCDPAgent(): Boolean
+
   @DoNotStrip public fun inspectorEnableModernCDPRegistry(): Boolean
 
   @DoNotStrip public fun skipMountHookNotifications(): Boolean

packages/react-native/ReactAndroid/src/main/jni/react/featureflags/JReactNativeFeatureFlagsCxxInterop.cpp

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<d697a8ac9c347c63a5fd592bccbfb8b5>>
+ * @generated SignedSource<<c867f3ceebcfbe24329a195ebf7a52cd>>
  */
 
 /**
@@ -93,6 +93,12 @@ class ReactNativeFeatureFlagsProviderHolder
     return method(javaProvider_);
   }
 
+  bool inspectorEnableHermesCDPAgent() override {
+    static const auto method =
+        getReactNativeFeatureFlagsProviderJavaClass()->getMethod<jboolean()>("inspectorEnableHermesCDPAgent");
+    return method(javaProvider_);
+  }
+
   bool inspectorEnableModernCDPRegistry() override {
     static const auto method =
         getReactNativeFeatureFlagsProviderJavaClass()->getMethod<jboolean()>("inspectorEnableModernCDPRegistry");
@@ -160,6 +166,11 @@ bool JReactNativeFeatureFlagsCxxInterop::inspectorEnableCxxInspectorPackagerConn
   return ReactNativeFeatureFlags::inspectorEnableCxxInspectorPackagerConnection();
 }
 
+bool JReactNativeFeatureFlagsCxxInterop::inspectorEnableHermesCDPAgent(
+    facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop> /*unused*/) {
+  return ReactNativeFeatureFlags::inspectorEnableHermesCDPAgent();
+}
+
 bool JReactNativeFeatureFlagsCxxInterop::inspectorEnableModernCDPRegistry(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop> /*unused*/) {
   return ReactNativeFeatureFlags::inspectorEnableModernCDPRegistry();
@@ -219,6 +230,9 @@ void JReactNativeFeatureFlagsCxxInterop::registerNatives() {
       makeNativeMethod(
         "inspectorEnableCxxInspectorPackagerConnection",
         JReactNativeFeatureFlagsCxxInterop::inspectorEnableCxxInspectorPackagerConnection),
+      makeNativeMethod(
+        "inspectorEnableHermesCDPAgent",
+        JReactNativeFeatureFlagsCxxInterop::inspectorEnableHermesCDPAgent),
       makeNativeMethod(
         "inspectorEnableModernCDPRegistry",
         JReactNativeFeatureFlagsCxxInterop::inspectorEnableModernCDPRegistry),

packages/react-native/ReactAndroid/src/main/jni/react/featureflags/JReactNativeFeatureFlagsCxxInterop.h

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<c3bb3615d6a32333f4f20e9d204b5dbb>>
+ * @generated SignedSource<<24dfb31a32c16f44b9a0ed64d8fff25b>>
  */
 
 /**
@@ -57,6 +57,9 @@ class JReactNativeFeatureFlagsCxxInterop
   static bool inspectorEnableCxxInspectorPackagerConnection(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
 
+  static bool inspectorEnableHermesCDPAgent(
+    facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
+
   static bool inspectorEnableModernCDPRegistry(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
 

packages/react-native/ReactCommon/hermes/inspector-modern/chrome/HermesRuntimeTargetDelegate.cpp

@@ -5,8 +5,12 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-#include "HermesRuntimeTargetDelegate.h"
+#include <jsinspector-modern/InspectorFlags.h>
+#include <jsinspector-modern/RuntimeTarget.h>
+
 #include "HermesRuntimeAgentDelegate.h"
+#include "HermesRuntimeAgentDelegateNew.h"
+#include "HermesRuntimeTargetDelegate.h"
 
 #ifdef HERMES_ENABLE_DEBUGGER
 #include <hermes/cdp/CDPDebugAPI.h>
@@ -23,16 +27,21 @@ namespace facebook::react::jsinspector_modern {
 class HermesRuntimeTargetDelegate::Impl : public RuntimeTargetDelegate {
  public:
 #ifdef HERMES_ENABLE_DEBUGGER
-  explicit Impl(std::shared_ptr<HermesRuntime> hermesRuntime)
-      : runtime_(std::move(hermesRuntime)),
+  explicit Impl(
+      HermesRuntimeTargetDelegate& delegate,
+      std::shared_ptr<HermesRuntime> hermesRuntime)
+      : delegate_(delegate),
+        runtime_(std::move(hermesRuntime)),
         cdpDebugAPI_(CDPDebugAPI::create(*runtime_)) {}
 
   CDPDebugAPI& getCDPDebugAPI() {
     return *cdpDebugAPI_;
   }
 #else
-  explicit Impl(std::shared_ptr<HermesRuntime> hermesRuntime)
-      : runtime_(std::move(hermesRuntime)) {}
+  explicit Impl(
+      HermesRuntimeTargetDelegate& delegate,
+      std::shared_ptr<HermesRuntime> hermesRuntime)
+      : delegate_(delegate), runtime_(std::move(hermesRuntime)) {}
 #endif
 
   // RuntimeTargetDelegate methods
@@ -44,16 +53,29 @@ class HermesRuntimeTargetDelegate::Impl : public RuntimeTargetDelegate {
           previouslyExportedState,
       const ExecutionContextDescription& executionContextDescription,
       RuntimeExecutor runtimeExecutor) override {
-    return std::unique_ptr<RuntimeAgentDelegate>(new HermesRuntimeAgentDelegate(
-        frontendChannel,
-        sessionState,
-        std::move(previouslyExportedState),
-        executionContextDescription,
-        runtime_,
-        std::move(runtimeExecutor)));
+    auto& inspectorFlags = InspectorFlags::getInstance();
+
+    return inspectorFlags.getEnableHermesCDPAgent()
+        ? std::unique_ptr<RuntimeAgentDelegate>(
+              new HermesRuntimeAgentDelegateNew(
+                  frontendChannel,
+                  sessionState,
+                  std::move(previouslyExportedState),
+                  executionContextDescription,
+                  *runtime_,
+                  delegate_,
+                  std::move(runtimeExecutor)))
+        : std::unique_ptr<RuntimeAgentDelegate>(new HermesRuntimeAgentDelegate(
+              frontendChannel,
+              sessionState,
+              std::move(previouslyExportedState),
+              executionContextDescription,
+              runtime_,
+              std::move(runtimeExecutor)));
   }
 
  private:
+  HermesRuntimeTargetDelegate& delegate_;
   std::shared_ptr<HermesRuntime> runtime_;
 
 #ifdef HERMES_ENABLE_DEBUGGER
@@ -63,7 +85,7 @@ class HermesRuntimeTargetDelegate::Impl : public RuntimeTargetDelegate {
 
 HermesRuntimeTargetDelegate::HermesRuntimeTargetDelegate(
     std::shared_ptr<HermesRuntime> hermesRuntime)
-    : impl_(std::make_unique<Impl>(std::move(hermesRuntime))) {}
+    : impl_(std::make_unique<Impl>(*this, std::move(hermesRuntime))) {}
 
 HermesRuntimeTargetDelegate::~HermesRuntimeTargetDelegate() = default;
 

packages/react-native/ReactCommon/jsinspector-modern/InspectorFlags.cpp

@@ -22,7 +22,9 @@ InspectorFlags::InspectorFlags()
           ReactNativeFeatureFlags::inspectorEnableModernCDPRegistry()),
       enableCxxInspectorPackagerConnection_(
           ReactNativeFeatureFlags::
-              inspectorEnableCxxInspectorPackagerConnection()) {}
+              inspectorEnableCxxInspectorPackagerConnection()),
+      enableHermesCDPAgent_(
+          ReactNativeFeatureFlags::inspectorEnableHermesCDPAgent()) {}
 
 bool InspectorFlags::getEnableModernCDPRegistry() const {
   assertFlagsMatchUpstream();
@@ -37,6 +39,11 @@ bool InspectorFlags::getEnableCxxInspectorPackagerConnection() const {
       enableModernCDPRegistry_;
 }
 
+bool InspectorFlags::getEnableHermesCDPAgent() const {
+  assertFlagsMatchUpstream();
+  return enableHermesCDPAgent_;
+}
+
 void InspectorFlags::dangerouslyResetFlags() {
   *this = InspectorFlags{};
 }
@@ -50,7 +57,9 @@ void InspectorFlags::assertFlagsMatchUpstream() const {
           ReactNativeFeatureFlags::inspectorEnableModernCDPRegistry() ||
       enableCxxInspectorPackagerConnection_ !=
           ReactNativeFeatureFlags::
-              inspectorEnableCxxInspectorPackagerConnection()) {
+              inspectorEnableCxxInspectorPackagerConnection() ||
+      ReactNativeFeatureFlags::inspectorEnableHermesCDPAgent() !=
+          enableHermesCDPAgent_) {
     LOG(ERROR)
         << "[InspectorFlags] Error: One or more ReactNativeFeatureFlags values "
         << "have changed during the global app lifetime. This may lead to "

packages/react-native/ReactCommon/jsinspector-modern/InspectorFlags.h

@@ -30,6 +30,11 @@ class InspectorFlags {
    */
   bool getEnableCxxInspectorPackagerConnection() const;
 
+  /**
+   * Flag determining if the new Hermes CDPAgent API should be enabled.
+   */
+  bool getEnableHermesCDPAgent() const;
+
   /**
    * Reset flags to their upstream values. The caller must ensure any resources
    * that have read previous flag values have been cleaned up.
@@ -44,6 +49,7 @@ class InspectorFlags {
 
   bool enableModernCDPRegistry_;
   bool enableCxxInspectorPackagerConnection_;
+  bool enableHermesCDPAgent_;
 
   mutable bool inconsistentFlagsStateLogged_{false};
   void assertFlagsMatchUpstream() const;

packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlags.cpp

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<fd7ff07ffc0f5f7b2d553a6b5064a1c0>>
+ * @generated SignedSource<<d85ce9d83e0ea9aa93923e81e2ffaec0>>
  */
 
 /**
@@ -57,6 +57,10 @@ bool ReactNativeFeatureFlags::inspectorEnableCxxInspectorPackagerConnection() {
   return getAccessor().inspectorEnableCxxInspectorPackagerConnection();
 }
 
+bool ReactNativeFeatureFlags::inspectorEnableHermesCDPAgent() {
+  return getAccessor().inspectorEnableHermesCDPAgent();
+}
+
 bool ReactNativeFeatureFlags::inspectorEnableModernCDPRegistry() {
   return getAccessor().inspectorEnableModernCDPRegistry();
 }

packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlags.h

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<cbf10b0a7ed3d4892d53e5ae2319f4a8>>
+ * @generated SignedSource<<e4631762e5a422465444236542d9c3aa>>
  */
 
 /**
@@ -82,6 +82,11 @@ class ReactNativeFeatureFlags {
    */
   RN_EXPORT static bool inspectorEnableCxxInspectorPackagerConnection();
 
+  /**
+   * Flag determining if the new Hermes CDPAgent API should be enabled in the modern CDP backend. This flag is global and should not be changed across React Host lifetimes.
+   */
+  RN_EXPORT static bool inspectorEnableHermesCDPAgent();
+
   /**
    * Flag determining if the modern CDP backend should be enabled. This flag is global and should not be changed across React Host lifetimes.
    */

packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsAccessor.cpp

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<6c1e6b6a51cd6fdddae40d3b61ae2b36>>
+ * @generated SignedSource<<940e03ab78a13e5486802c13861be739>>
  */
 
 /**
@@ -191,6 +191,24 @@ bool ReactNativeFeatureFlagsAccessor::inspectorEnableCxxInspectorPackagerConnect
   return flagValue.value();
 }
 
+bool ReactNativeFeatureFlagsAccessor::inspectorEnableHermesCDPAgent() {
+  auto flagValue = inspectorEnableHermesCDPAgent_.load();
+
+  if (!flagValue.has_value()) {
+    // This block is not exclusive but it is not necessary.
+    // If multiple threads try to initialize the feature flag, we would only
+    // be accessing the provider multiple times but the end state of this
+    // instance and the returned flag value would be the same.
+
+    markFlagAsAccessed(9, "inspectorEnableHermesCDPAgent");
+
+    flagValue = currentProvider_->inspectorEnableHermesCDPAgent();
+    inspectorEnableHermesCDPAgent_ = flagValue;
+  }
+
+  return flagValue.value();
+}
+
 bool ReactNativeFeatureFlagsAccessor::inspectorEnableModernCDPRegistry() {
   auto flagValue = inspectorEnableModernCDPRegistry_.load();
 
@@ -200,7 +218,7 @@ bool ReactNativeFeatureFlagsAccessor::inspectorEnableModernCDPRegistry() {
     // be accessing the provider multiple times but the end state of this
     // instance and the returned flag value would be the same.
 
-    markFlagAsAccessed(9, "inspectorEnableModernCDPRegistry");
+    markFlagAsAccessed(10, "inspectorEnableModernCDPRegistry");
 
     flagValue = currentProvider_->inspectorEnableModernCDPRegistry();
     inspectorEnableModernCDPRegistry_ = flagValue;
@@ -218,7 +236,7 @@ bool ReactNativeFeatureFlagsAccessor::skipMountHookNotifications() {
     // be accessing the provider multiple times but the end state of this
     // instance and the returned flag value would be the same.
 
-    markFlagAsAccessed(10, "skipMountHookNotifications");
+    markFlagAsAccessed(11, "skipMountHookNotifications");
 
     flagValue = currentProvider_->skipMountHookNotifications();
     skipMountHookNotifications_ = flagValue;
@@ -236,7 +254,7 @@ bool ReactNativeFeatureFlagsAccessor::useModernRuntimeScheduler() {
     // be accessing the provider multiple times but the end state of this
     // instance and the returned flag value would be the same.
 
-    markFlagAsAccessed(11, "useModernRuntimeScheduler");
+    markFlagAsAccessed(12, "useModernRuntimeScheduler");
 
     flagValue = currentProvider_->useModernRuntimeScheduler();
     useModernRuntimeScheduler_ = flagValue;

packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsAccessor.h

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<4c5446d5b72429d090e17523f2d544a7>>
+ * @generated SignedSource<<aae94eb2b905f05e69a8a46abe53f60d>>
  */
 
 /**
@@ -40,6 +40,7 @@ class ReactNativeFeatureFlagsAccessor {
   bool enableMountHooksAndroid();
   bool enableSpannableBuildingUnification();
   bool inspectorEnableCxxInspectorPackagerConnection();
+  bool inspectorEnableHermesCDPAgent();
   bool inspectorEnableModernCDPRegistry();
   bool skipMountHookNotifications();
   bool useModernRuntimeScheduler();
@@ -53,7 +54,7 @@ class ReactNativeFeatureFlagsAccessor {
   std::unique_ptr<ReactNativeFeatureFlagsProvider> currentProvider_;
   bool wasOverridden_;
 
-  std::array<std::atomic<const char*>, 12> accessedFeatureFlags_;
+  std::array<std::atomic<const char*>, 13> accessedFeatureFlags_;
 
   std::atomic<std::optional<bool>> commonTestFlag_;
   std::atomic<std::optional<bool>> batchRenderingUpdatesInEventLoop_;
@@ -64,6 +65,7 @@ class ReactNativeFeatureFlagsAccessor {
   std::atomic<std::optional<bool>> enableMountHooksAndroid_;
   std::atomic<std::optional<bool>> enableSpannableBuildingUnification_;
   std::atomic<std::optional<bool>> inspectorEnableCxxInspectorPackagerConnection_;
+  std::atomic<std::optional<bool>> inspectorEnableHermesCDPAgent_;
   std::atomic<std::optional<bool>> inspectorEnableModernCDPRegistry_;
   std::atomic<std::optional<bool>> skipMountHookNotifications_;
   std::atomic<std::optional<bool>> useModernRuntimeScheduler_;

packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsDefaults.h

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<95e3fd7cf662623e3c09b093649d4ff2>>
+ * @generated SignedSource<<c63cd0b38dfa9c4d6843a4b879f8f4df>>
  */
 
 /**
@@ -63,6 +63,10 @@ class ReactNativeFeatureFlagsDefaults : public ReactNativeFeatureFlagsProvider {
     return false;
   }
 
+  bool inspectorEnableHermesCDPAgent() override {
+    return false;
+  }
+
   bool inspectorEnableModernCDPRegistry() override {
     return false;
   }

packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsProvider.h

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<26990a0a11bb2d7cf8510773b6ece099>>
+ * @generated SignedSource<<e9d6fc551ceeb457c501e71cb52b9e6d>>
  */
 
 /**
@@ -34,6 +34,7 @@ class ReactNativeFeatureFlagsProvider {
   virtual bool enableMountHooksAndroid() = 0;
   virtual bool enableSpannableBuildingUnification() = 0;
   virtual bool inspectorEnableCxxInspectorPackagerConnection() = 0;
+  virtual bool inspectorEnableHermesCDPAgent() = 0;
   virtual bool inspectorEnableModernCDPRegistry() = 0;
   virtual bool skipMountHookNotifications() = 0;
   virtual bool useModernRuntimeScheduler() = 0;

packages/react-native/ReactCommon/react/nativemodule/featureflags/NativeReactNativeFeatureFlags.cpp

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<4f7daa629ad90a9ab2fdc99e7c51e355>>
+ * @generated SignedSource<<a8b6653bdde573c793667b6d7ce3f0dd>>
  */
 
 /**
@@ -82,6 +82,11 @@ bool NativeReactNativeFeatureFlags::inspectorEnableCxxInspectorPackagerConnectio
   return ReactNativeFeatureFlags::inspectorEnableCxxInspectorPackagerConnection();
 }
 
+bool NativeReactNativeFeatureFlags::inspectorEnableHermesCDPAgent(
+    jsi::Runtime& /*runtime*/) {
+  return ReactNativeFeatureFlags::inspectorEnableHermesCDPAgent();
+}
+
 bool NativeReactNativeFeatureFlags::inspectorEnableModernCDPRegistry(
     jsi::Runtime& /*runtime*/) {
   return ReactNativeFeatureFlags::inspectorEnableModernCDPRegistry();

packages/react-native/ReactCommon/react/nativemodule/featureflags/NativeReactNativeFeatureFlags.h

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<b10df028d57c3aebd1972bc4624d1b84>>
+ * @generated SignedSource<<e7305f923500dbd9b5e1b8d0217156ef>>
  */
 
 /**
@@ -54,6 +54,8 @@ class NativeReactNativeFeatureFlags
 
   bool inspectorEnableCxxInspectorPackagerConnection(jsi::Runtime& runtime);
 
+  bool inspectorEnableHermesCDPAgent(jsi::Runtime& runtime);
+
   bool inspectorEnableModernCDPRegistry(jsi::Runtime& runtime);
 
   bool skipMountHookNotifications(jsi::Runtime& runtime);

packages/react-native/scripts/featureflags/ReactNativeFeatureFlags.config.js

@@ -72,6 +72,11 @@ const definitions: FeatureFlagDefinitions = {
       description:
         'Flag determining if the C++ implementation of InspectorPackagerConnection should be used instead of the per-platform one. This flag is global and should not be changed across React Host lifetimes.',
     },
+    inspectorEnableHermesCDPAgent: {
+      defaultValue: false,
+      description:
+        'Flag determining if the new Hermes CDPAgent API should be enabled in the modern CDP backend. This flag is global and should not be changed across React Host lifetimes.',
+    },
     inspectorEnableModernCDPRegistry: {
       defaultValue: false,
       description:

packages/react-native/src/private/featureflags/NativeReactNativeFeatureFlags.js

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<ef52ae50a916af01ceaaaa6683f6ec5e>>
+ * @generated SignedSource<<6a401351e670388135bec038018d3fe8>>
  * @flow strict-local
  */
 
@@ -32,6 +32,7 @@ export interface Spec extends TurboModule {
   +enableMountHooksAndroid?: () => boolean;
   +enableSpannableBuildingUnification?: () => boolean;
   +inspectorEnableCxxInspectorPackagerConnection?: () => boolean;
+  +inspectorEnableHermesCDPAgent?: () => boolean;
   +inspectorEnableModernCDPRegistry?: () => boolean;
   +skipMountHookNotifications?: () => boolean;
   +useModernRuntimeScheduler?: () => boolean;

packages/react-native/src/private/featureflags/ReactNativeFeatureFlags.js

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<5d1eca67ace8cccc336a6c6f65b40c99>>
+ * @generated SignedSource<<66678139be02293ff532e8e125ccc608>>
  * @flow strict-local
  */
 
@@ -49,6 +49,7 @@ export type ReactNativeFeatureFlags = {
   enableMountHooksAndroid: Getter<boolean>,
   enableSpannableBuildingUnification: Getter<boolean>,
   inspectorEnableCxxInspectorPackagerConnection: Getter<boolean>,
+  inspectorEnableHermesCDPAgent: Getter<boolean>,
   inspectorEnableModernCDPRegistry: Getter<boolean>,
   skipMountHookNotifications: Getter<boolean>,
   useModernRuntimeScheduler: Getter<boolean>,
@@ -130,6 +131,10 @@ export const enableSpannableBuildingUnification: Getter<boolean> = createNativeF
  * Flag determining if the C++ implementation of InspectorPackagerConnection should be used instead of the per-platform one. This flag is global and should not be changed across React Host lifetimes.
  */
 export const inspectorEnableCxxInspectorPackagerConnection: Getter<boolean> = createNativeFlagGetter('inspectorEnableCxxInspectorPackagerConnection', false);
+/**
+ * Flag determining if the new Hermes CDPAgent API should be enabled in the modern CDP backend. This flag is global and should not be changed across React Host lifetimes.
+ */
+export const inspectorEnableHermesCDPAgent: Getter<boolean> = createNativeFlagGetter('inspectorEnableHermesCDPAgent', false);
 /**
  * Flag determining if the modern CDP backend should be enabled. This flag is global and should not be changed across React Host lifetimes.
  */