facebook · j-piasecki · Nov 18, 2025
diff --git a/.github/actions/maestro-android/action.yml b/.github/actions/maestro-android/action.yml
@@ -22,6 +22,10 @@ inputs:
     required: false
     default: "."
     description: The directory from which metro should be started
+  emulator-arch:
+    required: false
+    default: x86
+    description: The architecture of the emulator to run
 
 runs:
   using: composite
@@ -53,7 +57,7 @@ runs:
       uses: reactivecircus/android-emulator-runner@v2
       with:
         api-level: 24
-        arch: x86
+        arch: ${{ inputs.emulator-arch }}
         ram-size: '8192M'
         heap-size: '4096M'
         disk-size: '10G'
@@ -72,13 +76,13 @@ runs:
       uses: actions/upload-artifact@v4.3.4
       if: always()
       with:
-        name: e2e_android_${{ steps.normalize-app-id.outputs.app-id }}_report_${{ inputs.flavor }}_NewArch
+        name: e2e_android_${{ steps.normalize-app-id.outputs.app-id }}_report_${{ inputs.flavor }}_${{ inputs.emulator-arch }}_NewArch
         path: |
           report.xml
           screen.mp4
     - name: Store Logs
       if: steps.run-tests.outcome == 'failure'
       uses: actions/upload-artifact@v4.3.4
       with:
-        name: maestro-logs-android-${{ steps.normalize-app-id.outputs.app-id }}-${{ inputs.flavor }}-NewArch
+        name: maestro-logs-android-${{ steps.normalize-app-id.outputs.app-id }}-${{ inputs.flavor }}-${{ inputs.emulator-arch }}-NewArch
         path: /tmp/MaestroLogs
diff --git a/.github/actions/prepare-hermes-v1-app/action.yml b/.github/actions/prepare-hermes-v1-app/action.yml
@@ -0,0 +1,41 @@
+name: prepare-hermes-v1-app
+description: Prepares a React Native app with Hermes V1 enabled
+inputs:
+  retry-count:
+    description: 'Number of times to retry the yarn install on failure'
+runs:
+  using: composite
+  steps:
+    - name: Create new app
+      shell: bash
+      run: |
+        cd /tmp
+        npx @react-native-community/cli init RNApp --skip-install --version nightly
+
+    - name: Select latest Hermes V1 version
+      shell: bash
+      run: |
+        node "$GITHUB_WORKSPACE/.github/workflow-scripts/selectLatestHermesV1Version.js"
+
+    - name: Apply patch to enable Hermes V1
+      shell: bash
+      run: |
+        cd /tmp/RNApp
+        git apply --binary --3way --whitespace=nowarn "$GITHUB_WORKSPACE/.github/workflow-scripts/hermes-v1.patch"
+        echo "✅ Patch applied successfully"
+
+    - name: Install app dependencies with retry
+      uses: nick-fields/retry@v3
+      with:
+        timeout_minutes: 10
+        max_attempts: ${{ inputs.retry-count }}
+        retry_wait_seconds: 15
+        shell: bash
+        command: |
+          cd /tmp/RNApp
+          yarn install
+        on_retry_command: |
+          echo "Cleaning up for yarn retry..."
+          cd /tmp/RNApp
+          rm -rf node_modules yarn.lock || true
+          yarn cache clean || true
diff --git a/.github/workflow-scripts/hermes-v1.patch b/.github/workflow-scripts/hermes-v1.patch
@@ -0,0 +1,30 @@
+diff --git a/android/settings.gradle b/android/settings.gradle
+index 63b5d4e..6359ec3 100644
+--- a/android/settings.gradle
++++ b/android/settings.gradle
+@@ -4,3 +4,11 @@ extensions.configure(com.facebook.react.ReactSettingsExtension){ ex -> ex.autoli
+ rootProject.name = 'RNApp'
+ include ':app'
+ includeBuild('../node_modules/@react-native/gradle-plugin')
++
++includeBuild('../node_modules/react-native') {
++  dependencySubstitution {
++    substitute(module("com.facebook.react:react-android")).using(project(":packages:react-native:ReactAndroid"))
++    substitute(module("com.facebook.react:react-native")).using(project(":packages:react-native:ReactAndroid"))
++    substitute(project(":packages:react-native:ReactAndroid:hermes-engine")).using(module("com.facebook.hermes:hermes-android:$HERMES_V1_VERSION"))
++  }
++}
+diff --git a/package.json b/package.json
+index f05d51b..69938af 100644
+--- a/package.json
++++ b/package.json
+@@ -35,6 +35,9 @@
+     "react-test-renderer": "19.2.0",
+     "typescript": "^5.8.3"
+   },
++  "resolutions": {
++    "hermes-compiler": "$HERMES_V1_VERSION"
++  },
+   "engines": {
+     "node": ">=20"
+   }
diff --git a/.github/workflow-scripts/selectLatestHermesV1Version.js b/.github/workflow-scripts/selectLatestHermesV1Version.js
@@ -0,0 +1,38 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+const { execSync } = require('child_process');
+const fs = require('fs');
+const path = require('path');
+
+const PATCH_FILE_PATH = path.join(__dirname, 'hermes-v1.patch');
+
+function getLatestHermesV1Version() {
+  const npmString = "npm view hermes-compiler@latest-v1 version";
+
+  try {
+    const result = execSync(npmString, { stdio: ['ignore', 'pipe', 'ignore'] }).toString().trim();
+    return result;
+  } catch (error) {
+    throw new Error(`Failed to get package version for hermes-compiler@latest-v1`);
+  }
+}
+
+function setHermesV1VersionInPatch(version) {
+  if (!fs.existsSync(PATCH_FILE_PATH)) {
+    throw new Error(`Patch file not found at path: ${PATCH_FILE_PATH}`);
+  }
+
+  let patchContent = fs.readFileSync(PATCH_FILE_PATH, 'utf8');
+  const updatedContent = patchContent.replaceAll(
+    "$HERMES_V1_VERSION",
+    version
+  );
+  fs.writeFileSync(PATCH_FILE_PATH, updatedContent, 'utf8');
+}
+
+setHermesV1VersionInPatch(getLatestHermesV1Version());
diff --git a/.github/workflows/test-hermes-v1-android.yml b/.github/workflows/test-hermes-v1-android.yml
@@ -0,0 +1,70 @@
+name: Test Hermes V1 with nightly on Android
+
+on:
+  workflow_call:
+    inputs:
+      retry-count:
+        description: 'Number of times to retry the build on failure'
+        required: false
+        type: number
+        default: 3
+
+jobs:
+  test-hermes-v1-android:
+    name: Test Hermes V1 on Android
+    runs-on: 4-core-ubuntu
+    strategy:
+      matrix:
+        flavor: [debug, release]
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '22.14.0'
+          cache: yarn
+
+      - name: Set up JDK 17
+        uses: actions/setup-java@v2
+        with:
+          java-version: '17'
+          distribution: 'zulu'
+
+      - name: Prepare the app with Hermes V1
+        uses: ./.github/actions/prepare-hermes-v1-app
+        with:
+          retry-count: ${{ inputs.retry-count }}
+
+      - name: Build Android with retry
+        uses: nick-fields/retry@v3
+        env:
+          CMAKE_VERSION: 3.31.5
+          ORG_GRADLE_PROJECT_reactNativeArchitectures: x86_64
+        with:
+          timeout_minutes: 45
+          max_attempts: ${{ inputs.retry-count }}
+          retry_wait_seconds: 30
+          shell: bash
+          command: |
+            cd /tmp/RNApp/android
+            CAPITALIZED_FLAVOR=$(echo "${{ matrix.flavor }}" | awk '{print toupper(substr($0, 1, 1)) substr($0, 2)}')
+            ./gradlew assemble${CAPITALIZED_FLAVOR} -PhermesV1Enabled=true
+          on_retry_command: |
+            echo "Cleaning up for Android retry..."
+            cd /tmp/RNApp/android
+            ./gradlew clean || true
+            rm -rf build app/build .gradle || true
+
+      - name: Run E2E Tests
+        uses: ./.github/actions/maestro-android
+        timeout-minutes: 60
+        with:
+          app-path: /tmp/RNApp/android/app/build/outputs/apk/${{ matrix.flavor }}/app-${{ matrix.flavor }}.apk
+          app-id: com.rnapp
+          maestro-flow: ./scripts/e2e/.maestro/
+          install-java: 'false'
+          flavor: ${{ matrix.flavor }}
+          working-directory: /tmp/RNApp
+          emulator-arch: x86_64
diff --git a/.github/workflows/test-hermes-v1-ios.yml b/.github/workflows/test-hermes-v1-ios.yml
@@ -0,0 +1,78 @@
+name: Test Hermes V1 with nightly on iOS
+
+on:
+  workflow_call:
+    inputs:
+      retry-count:
+        description: 'Number of times to retry the build on failure'
+        required: false
+        type: number
+        default: 3
+
+jobs:
+  test-hermes-v1-ios:
+    name: Test Hermes V1 on iOS
+    runs-on: macos-15-large
+    strategy:
+      matrix:
+        flavor: [debug, release]
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '22.14.0'
+          cache: yarn
+
+      - name: Prepare capitalized flavor
+        id: prepare-flavor
+        shell: bash
+        run: |
+          CAPITALIZED_FLAVOR=$(echo "${{ matrix.flavor }}" | awk '{print toupper(substr($0, 1, 1)) substr($0, 2)}')
+          echo "capitalized_flavor=$CAPITALIZED_FLAVOR" >> $GITHUB_OUTPUT
+
+      - name: Prepare the app with Hermes V1
+        uses: ./.github/actions/prepare-hermes-v1-app
+        with:
+          retry-count: ${{ inputs.retry-count }}
+
+      - name: Setup xcode
+        uses: maxim-lobanov/setup-xcode@v1
+        with:
+          xcode-version: 16.4.0
+
+      - name: Build iOS with retry
+        uses: nick-fields/retry@v3
+        with:
+          timeout_minutes: 45
+          max_attempts: ${{ inputs.retry-count }}
+          retry_wait_seconds: 30
+          shell: bash
+          command: |
+            cd /tmp/RNApp/ios
+            bundle install
+            RCT_HERMES_V1_ENABLED=1 bundle exec pod install
+            xcodebuild build \
+              -workspace "RNApp.xcworkspace" \
+              -scheme "RNApp" \
+              -configuration "${{ steps.prepare-flavor.outputs.capitalized_flavor }}" \
+              -sdk "iphonesimulator" \
+              -destination "generic/platform=iOS Simulator" \
+              -derivedDataPath "/tmp/RNApp" \
+              -quiet
+          on_retry_command: |
+            echo "Cleaning up for iOS retry..."
+            cd /tmp/RNApp/ios
+            rm -rf Pods Podfile.lock build
+            rm -rf ~/Library/Developer/Xcode/DerivedData/* || true
+
+      - name: Run E2E Tests
+        uses: ./.github/actions/maestro-ios
+        with:
+          app-path: "/tmp/RNApp/Build/Products/${{ steps.prepare-flavor.outputs.capitalized_flavor }}-iphonesimulator/RNApp.app"
+          app-id: org.reactjs.native.example.RNApp
+          maestro-flow: ./scripts/e2e/.maestro/
+          flavor: ${{ steps.prepare-flavor.outputs.capitalized_flavor }}
+          working-directory: /tmp/RNApp
diff --git a/.github/workflows/test-hermes-v1.yml b/.github/workflows/test-hermes-v1.yml
@@ -0,0 +1,39 @@
+# This jobs runs every day 2 hours after the nightly job for React Native so we can verify how the nightly is behaving.
+name: Check Hermes V1 with the nightly build
+
+on:
+  workflow_dispatch:
+  # nightly build @ 4:15 AM UTC
+  schedule:
+    - cron: '15 4 * * *'
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event_name }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  check-nightly:
+    runs-on: ubuntu-latest
+    if: github.repository == 'facebook/react-native'
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - name: Check nightly
+        run: |
+          TODAY=$(date "+%Y%m%d")
+          echo "Checking nightly for $TODAY"
+          NIGHTLY="$(npm view react-native | grep $TODAY)"
+          if [[ -z $NIGHTLY ]]; then
+            echo 'Nightly job failed.'
+            exit 1
+          else
+            echo 'Nightly Worked, All Good!'
+          fi
+
+  test-hermes-v1-ios:
+    uses: ./.github/workflows/test-hermes-v1-ios.yml
+    needs: check-nightly
+
+  test-hermes-v1-android:
+    uses: ./.github/workflows/test-hermes-v1-android.yml
+    needs: check-nightly