Android: Add setBundleSource method to ReactHost for changing bundle URL at runtime (facebook#54139)

Summary:
Following the [RFC](react-native-community/discussions-and-proposals#933), this PR adds new `setBundleSource` methods to `ReactHost` for modifying bundle URL at runtime. The first one with signature:

```Kotlin
public fun setBundleSource(debugServerHost: String, moduleName: String, queryBuilder: (Map<String, String>) -> Map<String, String> = { it })
```

takes debugServerHost (set in packager connection settings), moduleName (set in DevSupportManager's jsAppBundleName), and queryBuilder (set in packager connection settings). Before updating settings, the packager connection is closed to reset the packager client, which will be newly created during reload with updated configuration.


The second one for loading bundle from the file takes single `filePath` argument:

```Kotlin
public fun setBundleSource(filePath: String)
```

It sets `customBundleFilePath` in `DevSupportManager` which has priority over other methods of loading the bundle in `jsBundleLoader` and reloads `ReactHost`.


## Changelog:

[ANDROID][ADDED] - added new `setBundleSource` method to `ReactHost` for changing bundle URL at runtime.


Test Plan:
Started with running two Metro instances on ports `8081` and `8082` (first with white background, second with blue). Created a native button that toggles `debugServerHost` port and invokes  `setBundleSource`.

https://github.com/user-attachments/assets/7afe2cbc-6fef-44bc-930c-e9f9c4edd2bd

For setting bundle file path, generated JS bundle with different background comparing to the one serving by Metro. Moved file to the `app/files` directory in android emulator and configured native button to invoke a `setBundleSource(filePath)`. 

https://github.com/user-attachments/assets/5e59d7b7-c6ae-475c-94e3-50d4ac69cf24




<details>

<summary>code:</summary>

Changing debug server host:

`RNTesterActivity.kt`:

```Kotlin
package com.facebook.react.uiapp

import android.content.res.Configuration
import android.graphics.Color
import android.os.Bundle
import android.view.View
import android.widget.Button
import android.widget.FrameLayout
import androidx.core.graphics.drawable.toDrawable
import androidx.core.view.ViewCompat
import androidx.core.view.WindowInsetsCompat
import com.facebook.common.logging.FLog
import com.facebook.react.FBRNTesterEndToEndHelper
import com.facebook.react.ReactActivity
import com.facebook.react.defaults.DefaultNewArchitectureEntryPoint.fabricEnabled
import com.facebook.react.defaults.DefaultReactActivityDelegate
import java.io.FileDescriptor
import java.io.PrintWriter

internal class RNTesterActivity : ReactActivity() {
  private var activePort = "8081"

  class RNTesterActivityDelegate(val activity: ReactActivity, mainComponentName: String) :
      DefaultReactActivityDelegate(activity, mainComponentName, fabricEnabled) {
    private val PARAM_ROUTE = "route"
    private lateinit var initialProps: Bundle

    override fun onCreate(savedInstanceState: Bundle?) {
      // Get remote param before calling super which uses it
      val bundle = activity.intent?.extras

      if (bundle != null && bundle.containsKey(PARAM_ROUTE)) {
        val routeUri = "rntester://example/${bundle.getString(PARAM_ROUTE)}Example"
        initialProps = Bundle().apply { putString("exampleFromAppetizeParams", routeUri) }
      }
      FBRNTesterEndToEndHelper.onCreate(activity.application)
      super.onCreate(savedInstanceState)
    }

    override fun getLaunchOptions() =
        if (this::initialProps.isInitialized) initialProps else Bundle()
  }

  private fun getButtonText(): String {
    return "Port: $activePort"
  }

  private fun setupPortButton(onClick: () -> Unit) {
    val portButton = Button(this).apply {
      text = getButtonText()
      setBackgroundColor(Color.rgb(0, 123, 255)) // Blue background
      setTextColor(Color.WHITE)
      setPadding(32, 16, 32, 16)
      textSize = 16f
      elevation = 8f
    }

    // Get the root view and add button to it
    val rootView = this.findViewById<FrameLayout>(android.R.id.content)
    val layoutParams = FrameLayout.LayoutParams(
      FrameLayout.LayoutParams.WRAP_CONTENT,
      FrameLayout.LayoutParams.WRAP_CONTENT
    ).apply {
      gravity = android.view.Gravity.TOP or android.view.Gravity.CENTER_HORIZONTAL
      topMargin = 200 // 50dp from top
    }

    rootView.addView(portButton, layoutParams)

    portButton.setOnClickListener {
      onClick()
      portButton.text = getButtonText()
    }
  }

  // set background color so it will show below transparent system bars on forced edge-to-edge
  private fun maybeUpdateBackgroundColor() {
    val isDarkMode =
        resources.configuration.uiMode and Configuration.UI_MODE_NIGHT_MASK ==
            Configuration.UI_MODE_NIGHT_YES

    val color =
        if (isDarkMode) {
          Color.rgb(11, 6, 0)
        } else {
          Color.rgb(243, 248, 255)
        }

    window?.setBackgroundDrawable(color.toDrawable())
  }

  override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)

    fullyDrawnReporter.addReporter()
    maybeUpdateBackgroundColor()

   reactDelegate?.reactHost?.let {
     setupPortButton {
       activePort = if (activePort == "8081") "8082" else "8081"
       reactHost.setBundleSource("10.0.2.2:$activePort", "js/RNTesterApp.android")
       // reactHost.setBundleSource("/data/user/0/com.facebook.react.uiapp/files/android.bundle")
     }
   }

    // register insets listener to update margins on the ReactRootView to avoid overlap w/ system
    // bars
    reactDelegate?.reactRootView?.let { rootView ->
      val insetsType: Int =
          WindowInsetsCompat.Type.systemBars() or WindowInsetsCompat.Type.displayCutout()

      val windowInsetsListener = { view: View, windowInsets: WindowInsetsCompat ->
        val insets = windowInsets.getInsets(insetsType)

        (view.layoutParams as FrameLayout.LayoutParams).apply {
          setMargins(insets.left, insets.top, insets.right, insets.bottom)
        }

        WindowInsetsCompat.CONSUMED
      }
      ViewCompat.setOnApplyWindowInsetsListener(rootView, windowInsetsListener)
    }
  }

  override fun onConfigurationChanged(newConfig: Configuration) {
    super.onConfigurationChanged(newConfig)

    // update background color on UI mode change
    maybeUpdateBackgroundColor()
  }

  override fun createReactActivityDelegate() = RNTesterActivityDelegate(this, mainComponentName)

  override fun getMainComponentName() = "RNTesterApp"

  override fun dump(
      prefix: String,
      fd: FileDescriptor?,
      writer: PrintWriter,
      args: Array<String>?,
  ) {
    FBRNTesterEndToEndHelper.maybeDump(prefix, writer, args)
  }
}

```

</detail>

Differential Revision: D84713639

Pulled By: coado

Author: coado

packages/react-native/ReactAndroid/api/ReactAndroid.api

@@ -239,6 +239,9 @@ public abstract interface class com/facebook/react/ReactHost {
 	public abstract fun reload (Ljava/lang/String;)Lcom/facebook/react/interfaces/TaskInterface;
 	public abstract fun removeBeforeDestroyListener (Lkotlin/jvm/functions/Function0;)V
 	public abstract fun removeReactInstanceEventListener (Lcom/facebook/react/ReactInstanceEventListener;)V
+	public fun setBundleSource (Ljava/lang/String;)V
+	public fun setBundleSource (Ljava/lang/String;Ljava/lang/String;Lkotlin/jvm/functions/Function1;)V
+	public static synthetic fun setBundleSource$default (Lcom/facebook/react/ReactHost;Ljava/lang/String;Ljava/lang/String;Lkotlin/jvm/functions/Function1;ILjava/lang/Object;)V
 	public abstract fun start ()Lcom/facebook/react/interfaces/TaskInterface;
 }
 
@@ -1898,7 +1901,7 @@ public final class com/facebook/react/devsupport/DefaultDevLoadingViewImplementa
 public class com/facebook/react/devsupport/DevServerHelper {
 	public fun <init> (Lcom/facebook/react/modules/debug/interfaces/DeveloperSettings;Landroid/content/Context;Lcom/facebook/react/packagerconnection/PackagerConnectionSettings;)V
 	public final fun closeInspectorConnection ()V
-	public final fun closePackagerConnection ()V
+	public final fun closePackagerConnection ()Landroid/os/AsyncTask;
 	public final fun disableDebugger ()V
 	public final fun downloadBundleFromURL (Lcom/facebook/react/devsupport/interfaces/DevBundleDownloadListener;Ljava/io/File;Ljava/lang/String;Lcom/facebook/react/devsupport/BundleDownloader$BundleInfo;)V
 	public final fun downloadBundleFromURL (Lcom/facebook/react/devsupport/interfaces/DevBundleDownloadListener;Ljava/io/File;Ljava/lang/String;Lcom/facebook/react/devsupport/BundleDownloader$BundleInfo;Lokhttp3/Request$Builder;)V
@@ -1925,7 +1928,8 @@ public abstract interface class com/facebook/react/devsupport/DevServerHelper$Pa
 
 public abstract class com/facebook/react/devsupport/DevSupportManagerBase : com/facebook/react/devsupport/interfaces/DevSupportManager {
 	public static final field Companion Lcom/facebook/react/devsupport/DevSupportManagerBase$Companion;
-	public fun <init> (Landroid/content/Context;Lcom/facebook/react/devsupport/ReactInstanceDevHelper;Ljava/lang/String;ZLcom/facebook/react/devsupport/interfaces/RedBoxHandler;Lcom/facebook/react/devsupport/interfaces/DevBundleDownloadListener;ILjava/util/Map;Lcom/facebook/react/common/SurfaceDelegateFactory;Lcom/facebook/react/devsupport/interfaces/DevLoadingViewManager;Lcom/facebook/react/devsupport/interfaces/PausedInDebuggerOverlayManager;)V
+	public fun <init> (Landroid/content/Context;Lcom/facebook/react/devsupport/ReactInstanceDevHelper;Ljava/lang/String;ZLcom/facebook/react/devsupport/interfaces/RedBoxHandler;Lcom/facebook/react/devsupport/interfaces/DevBundleDownloadListener;ILjava/util/Map;Lcom/facebook/react/common/SurfaceDelegateFactory;Lcom/facebook/react/devsupport/interfaces/DevLoadingViewManager;Lcom/facebook/react/devsupport/interfaces/PausedInDebuggerOverlayManager;Ljava/lang/String;)V
+	public synthetic fun <init> (Landroid/content/Context;Lcom/facebook/react/devsupport/ReactInstanceDevHelper;Ljava/lang/String;ZLcom/facebook/react/devsupport/interfaces/RedBoxHandler;Lcom/facebook/react/devsupport/interfaces/DevBundleDownloadListener;ILjava/util/Map;Lcom/facebook/react/common/SurfaceDelegateFactory;Lcom/facebook/react/devsupport/interfaces/DevLoadingViewManager;Lcom/facebook/react/devsupport/interfaces/PausedInDebuggerOverlayManager;Ljava/lang/String;ILkotlin/jvm/internal/DefaultConstructorMarker;)V
 	public fun addCustomDevOption (Ljava/lang/String;Lcom/facebook/react/devsupport/interfaces/DevOptionHandler;)V
 	public fun createRootView (Ljava/lang/String;)Landroid/view/View;
 	public fun createSurfaceDelegate (Ljava/lang/String;)Lcom/facebook/react/common/SurfaceDelegate;
@@ -1935,6 +1939,7 @@ public abstract class com/facebook/react/devsupport/DevSupportManagerBase : com/
 	protected final fun getApplicationContext ()Landroid/content/Context;
 	public fun getCurrentActivity ()Landroid/app/Activity;
 	public final fun getCurrentReactContext ()Lcom/facebook/react/bridge/ReactContext;
+	public fun getCustomBundleFilePath ()Ljava/lang/String;
 	public final fun getDevLoadingViewManager ()Lcom/facebook/react/devsupport/interfaces/DevLoadingViewManager;
 	public final fun getDevServerHelper ()Lcom/facebook/react/devsupport/DevServerHelper;
 	public final fun getDevSettings ()Lcom/facebook/react/modules/debug/interfaces/DeveloperSettings;
@@ -1964,10 +1969,12 @@ public abstract class com/facebook/react/devsupport/DevSupportManagerBase : com/
 	public fun reloadJSFromServer (Ljava/lang/String;Lcom/facebook/react/devsupport/interfaces/BundleLoadCallback;)V
 	public fun reloadSettings ()V
 	public fun setAdditionalOptionForPackager (Ljava/lang/String;Ljava/lang/String;)V
+	public fun setCustomBundleFilePath (Ljava/lang/String;)V
 	public final fun setDevLoadingViewManager (Lcom/facebook/react/devsupport/interfaces/DevLoadingViewManager;)V
 	public final fun setDevSupportEnabled (Z)V
 	public fun setFpsDebugEnabled (Z)V
 	public fun setHotModuleReplacementEnabled (Z)V
+	public final fun setJsAppBundleName (Ljava/lang/String;)V
 	public final fun setLastErrorCookie (I)V
 	public final fun setLastErrorStack ([Lcom/facebook/react/devsupport/interfaces/StackFrame;)V
 	public final fun setLastErrorTitle (Ljava/lang/String;)V
@@ -2131,6 +2138,7 @@ public abstract interface class com/facebook/react/devsupport/interfaces/DevSupp
 	public abstract fun downloadBundleResourceFromUrlSync (Ljava/lang/String;Ljava/io/File;)Ljava/io/File;
 	public abstract fun getCurrentActivity ()Landroid/app/Activity;
 	public abstract fun getCurrentReactContext ()Lcom/facebook/react/bridge/ReactContext;
+	public fun getCustomBundleFilePath ()Ljava/lang/String;
 	public abstract fun getDevSettings ()Lcom/facebook/react/modules/debug/interfaces/DeveloperSettings;
 	public abstract fun getDevSupportEnabled ()Z
 	public abstract fun getDownloadedJSBundleFile ()Ljava/lang/String;
@@ -2155,6 +2163,7 @@ public abstract interface class com/facebook/react/devsupport/interfaces/DevSupp
 	public abstract fun reloadJSFromServer (Ljava/lang/String;Lcom/facebook/react/devsupport/interfaces/BundleLoadCallback;)V
 	public abstract fun reloadSettings ()V
 	public abstract fun setAdditionalOptionForPackager (Ljava/lang/String;Ljava/lang/String;)V
+	public fun setCustomBundleFilePath (Ljava/lang/String;)V
 	public abstract fun setDevSupportEnabled (Z)V
 	public abstract fun setFpsDebugEnabled (Z)V
 	public abstract fun setHotModuleReplacementEnabled (Z)V
@@ -2993,6 +3002,8 @@ public class com/facebook/react/packagerconnection/PackagerConnectionSettings {
 	public fun resetDebugServerHost ()V
 	public final fun setAdditionalOptionForPackager (Ljava/lang/String;Ljava/lang/String;)V
 	public fun setDebugServerHost (Ljava/lang/String;)V
+	public final fun setPackagerOptionsUpdater (Lkotlin/jvm/functions/Function1;)V
+	public final fun updatePackagerOptions (Ljava/util/Map;)Ljava/util/Map;
 }
 
 public final class com/facebook/react/packagerconnection/ReconnectingWebSocket : okhttp3/WebSocketListener {
@@ -3071,6 +3082,8 @@ public final class com/facebook/react/runtime/ReactHostImpl : com/facebook/react
 	public fun reload (Ljava/lang/String;)Lcom/facebook/react/interfaces/TaskInterface;
 	public fun removeBeforeDestroyListener (Lkotlin/jvm/functions/Function0;)V
 	public fun removeReactInstanceEventListener (Lcom/facebook/react/ReactInstanceEventListener;)V
+	public fun setBundleSource (Ljava/lang/String;)V
+	public fun setBundleSource (Ljava/lang/String;Ljava/lang/String;Lkotlin/jvm/functions/Function1;)V
 	public fun start ()Lcom/facebook/react/interfaces/TaskInterface;
 }
 

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/ReactHost.kt

@@ -189,4 +189,21 @@ public interface ReactHost {
 
   /** Remove a listener previously added with [addReactInstanceEventListener]. */
   public fun removeReactInstanceEventListener(listener: ReactInstanceEventListener)
+
+  /** Sets the source of the bundle to be loaded from the file system. */
+  public fun setBundleSource(filePath: String): Unit = Unit
+
+  /**
+   * Sets the source of the bundle to be loaded from the packager server and updates the packager
+   * connection.
+   *
+   * @param debugServerHost host and port of the server, for example "localhost:8081"
+   * @param moduleName the module name to load, for example "js/RNTesterApp.android"
+   * @param queryBuilder a function that takes current packager options and returns updated options
+   */
+  public fun setBundleSource(
+      debugServerHost: String,
+      moduleName: String,
+      queryBuilder: (Map<String, String>) -> Map<String, String> = { it },
+  ): Unit = Unit
 }

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/devsupport/DevServerHelper.kt

@@ -196,16 +196,18 @@ public open class DevServerHelper(
         .executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR)
   }
 
-  public fun closePackagerConnection() {
-    object : AsyncTask<Void, Void, Void>() {
+  public fun closePackagerConnection(): AsyncTask<Void, Void, Void> {
+    val task =
+        object : AsyncTask<Void, Void, Void>() {
           @Deprecated("This class needs to be rewritten to don't use AsyncTasks")
           override fun doInBackground(vararg params: Void): Void? {
             packagerClient?.close()
             packagerClient = null
             return null
           }
         }
-        .executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR)
+    task.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR)
+    return task
   }
 
   public fun openInspectorConnection() {
@@ -280,7 +282,11 @@ public open class DevServerHelper(
   ): String {
     val dev = devMode
     val additionalOptionsBuilder = StringBuilder()
-    for ((key, value) in packagerConnectionSettings.additionalOptionsForPackager) {
+    val packagerOptions =
+        packagerConnectionSettings.updatePackagerOptions(
+            packagerConnectionSettings.additionalOptionsForPackager
+        )
+    for ((key, value) in packagerOptions) {
       if (value.isEmpty()) {
         continue
       }

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/devsupport/DevSupportManagerBase.kt

@@ -85,7 +85,7 @@ import java.util.Locale
 public abstract class DevSupportManagerBase(
     protected val applicationContext: Context,
     public val reactInstanceDevHelper: ReactInstanceDevHelper,
-    @get:JvmName("getJSAppBundleName") public val jsAppBundleName: String?,
+    @get:JvmName("getJSAppBundleName") public var jsAppBundleName: String?,
     enableOnCreate: Boolean,
     public override val redBoxHandler: RedBoxHandler?,
     private val devBundleDownloadListener: DevBundleDownloadListener?,
@@ -94,6 +94,7 @@ public abstract class DevSupportManagerBase(
     private val surfaceDelegateFactory: SurfaceDelegateFactory?,
     public var devLoadingViewManager: DevLoadingViewManager?,
     private var pausedInDebuggerOverlayManager: PausedInDebuggerOverlayManager?,
+    private var customBundleFilePathField: String? = null,
 ) : DevSupportManager {
 
   public interface CallbackWithBundleLoader {
@@ -132,6 +133,12 @@ public abstract class DevSupportManagerBase(
       reloadSettings()
     }
 
+  override var customBundleFilePath: String?
+    get() = customBundleFilePathField
+    set(value) {
+      customBundleFilePathField = value
+    }
+
   override val sourceMapUrl: String
     get() = jsAppBundleName?.let { devServerHelper.getSourceMapUrl(it) } ?: ""
 

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/devsupport/interfaces/DevSupportManager.kt

@@ -36,6 +36,10 @@ public interface DevSupportManager : JSExceptionHandler {
   public val currentActivity: Activity?
   public val currentReactContext: ReactContext?
 
+  public var customBundleFilePath: String?
+    get() = null
+    set(value) = Unit
+
   public var devSupportEnabled: Boolean
 
   public fun showNewJavaError(message: String?, e: Throwable)

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/packagerconnection/PackagerConnectionSettings.kt

@@ -4,30 +4,24 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  */
-
-@file:Suppress("DEPRECATION") // PreferenceManager should be migrated to androidx
-
 package com.facebook.react.packagerconnection
 
 import android.content.Context
-import android.content.SharedPreferences
-import android.preference.PreferenceManager
 import com.facebook.common.logging.FLog
 import com.facebook.react.modules.systeminfo.AndroidInfoHelpers
 
 public open class PackagerConnectionSettings(private val appContext: Context) {
-  private val preferences: SharedPreferences =
-      PreferenceManager.getDefaultSharedPreferences(appContext)
   public val packageName: String = appContext.packageName
   private val _additionalOptionsForPackager: MutableMap<String, String> = mutableMapOf()
+  private var _packagerOptionsUpdater: (Map<String, String>) -> Map<String, String> = { it }
+  private var cachedHost: String? = null
 
   public open var debugServerHost: String
     get() {
-      // Check host setting first. If empty try to detect emulator type and use default
+      // Check cached host first. If empty try to detect emulator type and use default
       // hostname for those
-      val hostFromSettings = preferences.getString(PREFS_DEBUG_SERVER_HOST_KEY, null)
-      if (!hostFromSettings.isNullOrEmpty()) {
-        return hostFromSettings
+      cachedHost?.let {
+        return it
       }
       val host = AndroidInfoHelpers.getServerHost(appContext)
       if (host == AndroidInfoHelpers.DEVICE_LOCALHOST) {
@@ -36,20 +30,29 @@ public open class PackagerConnectionSettings(private val appContext: Context) {
             "You seem to be running on device. Run '${AndroidInfoHelpers.getAdbReverseTcpCommand(appContext)}' to forward the debug server's port to the device.",
         )
       }
+
+      cachedHost = host
       return host
     }
     set(host) {
       if (host.isEmpty()) {
-        preferences.edit().remove(PREFS_DEBUG_SERVER_HOST_KEY).apply()
+        cachedHost = null
       } else {
-        preferences.edit().putString(PREFS_DEBUG_SERVER_HOST_KEY, host).apply()
+        cachedHost = host
       }
     }
 
   public open fun resetDebugServerHost() {
-    preferences.edit().remove(PREFS_DEBUG_SERVER_HOST_KEY).apply()
+    cachedHost = null
   }
 
+  public fun setPackagerOptionsUpdater(updater: (Map<String, String>) -> Map<String, String>) {
+    _packagerOptionsUpdater = updater
+  }
+
+  public fun updatePackagerOptions(options: Map<String, String>): Map<String, String> =
+      _packagerOptionsUpdater(options)
+
   public fun setAdditionalOptionForPackager(key: String, value: String) {
     _additionalOptionsForPackager[key] = value
   }
@@ -59,6 +62,5 @@ public open class PackagerConnectionSettings(private val appContext: Context) {
 
   private companion object {
     private val TAG = PackagerConnectionSettings::class.java.simpleName
-    private const val PREFS_DEBUG_SERVER_HOST_KEY = "debug_http_host"
   }
 }

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/runtime/ReactHostImpl.kt

@@ -73,6 +73,9 @@ import java.util.concurrent.atomic.AtomicInteger
 import java.util.concurrent.atomic.AtomicReference
 import kotlin.Unit
 import kotlin.concurrent.Volatile
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.launch
 
 /**
  * A ReactHost is an object that manages a single [ReactInstance]. A ReactHost can be constructed
@@ -643,6 +646,29 @@ public class ReactHostImpl(
     }
   }
 
+  @ThreadConfined(value = ThreadConfined.UI)
+  override fun setBundleSource(filePath: String) {
+    devSupportManager.customBundleFilePath = filePath
+    reload("Change bundle source")
+  }
+
+  @ThreadConfined(value = ThreadConfined.UI)
+  override fun setBundleSource(
+      debugServerHost: String,
+      moduleName: String,
+      queryBuilder: (Map<String, String>) -> Map<String, String>,
+  ) {
+    CoroutineScope(Dispatchers.Default).launch {
+      (devSupportManager as DevSupportManagerBase).devServerHelper.closePackagerConnection()
+      devSupportManager.devSettings.packagerConnectionSettings.let { it ->
+        it.setPackagerOptionsUpdater(queryBuilder)
+        it.debugServerHost = debugServerHost
+      }
+      devSupportManager.jsAppBundleName = moduleName
+      reload("Changed bundle source")
+    }
+  }
+
   @ThreadConfined(ThreadConfined.UI)
   override fun onConfigurationChanged(context: Context) {
     val currentReactContext = this.currentReactContext
@@ -1057,6 +1083,14 @@ public class ReactHostImpl(
     get() {
       stateTracker.enterState("getJSBundleLoader()")
 
+      if (devSupportManager.customBundleFilePath != null) {
+        return try {
+          Task.forResult(JSBundleLoader.createFileLoader(devSupportManager.customBundleFilePath!!))
+        } catch (e: Exception) {
+          Task.forError(e)
+        }
+      }
+
       if (useDevSupport && allowPackagerServerAccess) {
         return isMetroRunning.onSuccessTask(
             { task ->