refactor: replace inline node -e scripts with CLI entry point

Add a CLI interface to macosVersionResolver.js with two commands:
- download-hermes: downloads upstream tarball, writes outputs to $GITHUB_OUTPUT
- resolve-commit: resolves Hermes commit at merge base, writes to $GITHUB_OUTPUT

This replaces the multi-step node -e / temp file / shell JSON parsing
pattern in the workflow with clean one-liner script invocations.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Saadnajmi

.github/workflows/microsoft-resolve-hermes.yml

@@ -40,27 +40,12 @@ jobs:
       - name: Install npm dependencies
         run: yarn install
 
-      # Step 1: Try to download a prebuilt Hermes tarball from upstream Maven/Sonatype
+      # Step 1: Try to download a prebuilt Hermes tarball from upstream Maven/Sonatype.
+      # Writes tarball= and version= to $GITHUB_OUTPUT if successful.
       - name: Download upstream Hermes tarball
         id: download
         working-directory: packages/react-native
-        run: |
-          node -e "
-            const {downloadUpstreamHermesTarball} = require('./scripts/ios-prebuild/macosVersionResolver');
-            downloadUpstreamHermesTarball('Debug').then(r => {
-              require('fs').writeFileSync('/tmp/hermes-download-result.json', JSON.stringify(r));
-            });
-          "
-          RESULT=$(cat /tmp/hermes-download-result.json)
-          if [ "$RESULT" != "null" ]; then
-            TARBALL=$(node -e "console.log(JSON.parse(process.argv[1]).tarballPath)" "$RESULT")
-            VERSION=$(node -e "console.log(JSON.parse(process.argv[1]).version)" "$RESULT")
-            echo "tarball=$TARBALL" >> "$GITHUB_OUTPUT"
-            echo "version=$VERSION" >> "$GITHUB_OUTPUT"
-            echo "Downloaded upstream Hermes tarball for version $VERSION"
-          else
-            echo "No upstream tarball available"
-          fi
+        run: node scripts/ios-prebuild/macosVersionResolver.js download-hermes Debug
 
       # Step 2: If tarball found, recompose the xcframework to include the macOS slice.
       # Upstream tarballs contain a universal xcframework (iOS, simulator, catalyst,
@@ -134,10 +119,7 @@ jobs:
         if: steps.recompose.outputs.recomposed != 'true'
         id: resolve
         working-directory: packages/react-native
-        run: |
-          COMMIT=$(node -e "const {hermesCommitAtMergeBase} = require('./scripts/ios-prebuild/macosVersionResolver'); console.log(hermesCommitAtMergeBase().commit);" 2>&1 | grep -E '^[0-9a-f]{40}$')
-          echo "hermes-commit=$COMMIT" >> "$GITHUB_OUTPUT"
-          echo "Resolved Hermes commit: $COMMIT"
+        run: node scripts/ios-prebuild/macosVersionResolver.js resolve-commit
 
       - name: Restore Hermes cache
         if: steps.recompose.outputs.recomposed != 'true'

packages/react-native/scripts/ios-prebuild/macosVersionResolver.js

@@ -290,6 +290,47 @@ function abort(message /*: string */) {
   throw new Error(message);
 }
 
+/**
+ * Appends a key=value pair to the GitHub Actions output file ($GITHUB_OUTPUT).
+ * No-op if $GITHUB_OUTPUT is not set (e.g. running locally).
+ */
+function setActionOutput(key /*: string */, value /*: string */) {
+  const outputFile = process.env.GITHUB_OUTPUT;
+  if (outputFile) {
+    fs.appendFileSync(outputFile, `${key}=${value}\n`);
+  }
+}
+
+// CLI entry point: `node macosVersionResolver.js download-hermes [buildType]`
+// Writes tarball/version to $GITHUB_OUTPUT for use in GitHub Actions workflows.
+if (require.main === module) {
+  const [command, ...args] = process.argv.slice(2);
+
+  if (command === 'download-hermes') {
+    const buildType = args[0] || 'Debug';
+    downloadUpstreamHermesTarball(buildType).then(result => {
+      if (result != null) {
+        setActionOutput('tarball', result.tarballPath);
+        setActionOutput('version', result.version);
+        macosLog(
+          `Downloaded upstream Hermes tarball for version ${result.version}`,
+        );
+      } else {
+        macosLog('No upstream tarball available');
+      }
+    });
+  } else if (command === 'resolve-commit') {
+    const {commit} = hermesCommitAtMergeBase();
+    setActionOutput('hermes-commit', commit);
+    macosLog(`Resolved Hermes commit: ${commit}`);
+  } else {
+    console.error(
+      `Unknown command: ${command ?? '(none)'}. Available: download-hermes, resolve-commit`,
+    );
+    process.exit(1);
+  }
+}
+
 module.exports = {
   findMatchingHermesVersion,
   hermesCommitAtMergeBase,