From 2d2011c7ae0145369ad226417e9ecc3bf6df7890 Mon Sep 17 00:00:00 2001
From: Rob Hogan <robhogan@meta.com>
Date: Fri, 26 Sep 2025 08:13:44 -0700
Subject: [PATCH] Invalidate transform cache on update of/local changes to
 `@react-native/babel-preset` (#53867)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/53867

`react-native/metro-babel-transformer` implements `getCacheKey` for Metro, but does not vary the cache key on changes to `react-native/babel-preset`, one of its dependencies, leading to false positive cache hits (changes not being reflected).

This is particularly a problem in development, although it potentially also leads to issues in the unusual case that `react-native/babel-preset` is updated via npm, but no other package is.

This adds a `getCacheKey` to `react-native/babel-preset` and incorporates it into `react-native/metro-babel-transformer`'s `getCacheKey`. It's based on `package.json#version` in production and a hash of package contents in development (`version.endsWith('-main')`).

Changelog:
[General][Fixed] Invalidate transform cache when `react-native/babel-preset` is updated

Reviewed By: huntie

Differential Revision: D82893894

fbshipit-source-id: 9bbc034eaf68ee0e5b3078fb2fe8f30caa7f11c9
---
 .../react-native-babel-preset/src/index.js    | 30 +++++++++++++++++++
 .../src/index.js                              |  3 +-
 2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/packages/react-native-babel-preset/src/index.js b/packages/react-native-babel-preset/src/index.js
index 1d46f1ceef0..d2b5fc98721 100644
--- a/packages/react-native-babel-preset/src/index.js
+++ b/packages/react-native-babel-preset/src/index.js
@@ -10,11 +10,41 @@
 
 'use strict';
 
+const {version: packageVersion} = require('../package.json');
 const main = require('./configs/main');
 
 module.exports = function (babel, options) {
   return main(options);
 };
 
+let cacheKey;
+module.exports.getCacheKey = () => {
+  if (cacheKey != null) {
+    // Memoize
+    return cacheKey;
+  }
+  if (!packageVersion.endsWith('-main')) {
+    // Assume the integrity of package contents for published npm releases.
+    cacheKey = packageVersion;
+    return cacheKey;
+  }
+  // For anyone working with a `-main` version, contents may vary over time
+  // even though the version does not. Hash the relevant contents of this
+  // package. Lazy-load dependencies we only need on this slow path.
+  const {createHash} = require('crypto');
+  const {readFileSync} = require('fs');
+  const key = createHash('md5');
+  [
+    readFileSync(__filename),
+    readFileSync(require.resolve('./configs/main.js')),
+    readFileSync(require.resolve('./configs/hmr.js')),
+    readFileSync(require.resolve('./configs/lazy-imports.js')),
+    readFileSync(require.resolve('./passthrough-syntax-plugins.js')),
+    readFileSync(require.resolve('./plugin-warn-on-deep-imports.js')),
+  ].forEach(part => key.update(part));
+  cacheKey = key.digest('hex');
+  return cacheKey;
+};
+
 module.exports.getPreset = main.getPreset;
 module.exports.passthroughSyntaxPlugins = require('./passthrough-syntax-plugins');
diff --git a/packages/react-native-babel-transformer/src/index.js b/packages/react-native-babel-transformer/src/index.js
index 8ba7c3afe3d..d5e541c370a 100644
--- a/packages/react-native-babel-transformer/src/index.js
+++ b/packages/react-native-babel-transformer/src/index.js
@@ -23,13 +23,14 @@ import type {
 */
 
 const {parseSync, transformFromAstSync} = require('@babel/core');
+const {getCacheKey: getPresetCacheKey} = require('@react-native/babel-preset');
 const makeHMRConfig = require('@react-native/babel-preset/src/configs/hmr');
 const crypto = require('crypto');
 const fs = require('fs');
 const nullthrows = require('nullthrows');
 const path = require('path');
 
-const cacheKeyParts = [fs.readFileSync(__filename)];
+const cacheKeyParts = [getPresetCacheKey(), fs.readFileSync(__filename)];
 
 // TS detection conditions copied from @react-native/babel-preset
 function isTypeScriptSource(fileName /*: string */) {