From 5d47b7abd3f82dc4fa984b1b296fec1439567b76 Mon Sep 17 00:00:00 2001
From: Vladimir Morozov <vmorozov@microsoft.com>
Date: Tue, 18 Aug 2026 16:42:20 -0700
Subject: [PATCH] Recreate yarn.lock when preparing new release

---
 .../prepare-release/src/beachballBump.ts         | 16 ++++++++++++++++
 .../prepare-release/src/prepareRelease.ts        |  7 ++++++-
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/packages/@rnw-scripts/prepare-release/src/beachballBump.ts b/packages/@rnw-scripts/prepare-release/src/beachballBump.ts
index 8658d308d5e..23dcbb0655f 100644
--- a/packages/@rnw-scripts/prepare-release/src/beachballBump.ts
+++ b/packages/@rnw-scripts/prepare-release/src/beachballBump.ts
@@ -47,3 +47,19 @@ export async function bumpVersions(opts: {
     {cwd: opts.cwd},
   );
 }
+
+/**
+ * Regenerate yarn.lock so it matches the versions beachball just bumped.
+ *
+ * beachball rewrites package.json/changelogs but never touches the lockfile, so
+ * without this the lockfile drifts and every downstream `yarn install
+ * --immutable` fails with YN0028. `--mode=update-lockfile` refreshes the
+ * lockfile without touching node_modules; immutable installs are on by default
+ * under CI, so disable that for this one call.
+ */
+export async function updateLockfile(opts: {cwd: string}): Promise<void> {
+  await exec('yarn install --mode=update-lockfile', {
+    cwd: opts.cwd,
+    env: {YARN_ENABLE_IMMUTABLE_INSTALLS: 'false'},
+  });
+}
diff --git a/packages/@rnw-scripts/prepare-release/src/prepareRelease.ts b/packages/@rnw-scripts/prepare-release/src/prepareRelease.ts
index 3056f061de0..765f0875429 100644
--- a/packages/@rnw-scripts/prepare-release/src/prepareRelease.ts
+++ b/packages/@rnw-scripts/prepare-release/src/prepareRelease.ts
@@ -20,7 +20,7 @@ import findRepoRoot from '@react-native-windows/find-repo-root';
 
 import {GitRepo} from './git';
 import {findPR, createPR, updatePR} from './github';
-import {hasChangeFiles, bumpVersions} from './beachballBump';
+import {hasChangeFiles, bumpVersions, updateLockfile} from './beachballBump';
 import {
   collectBumpedPackages,
   generatePRBody,
@@ -288,6 +288,11 @@ async function detectRemote(git: GitRepo, repoUrl: string): Promise<string> {
         cwd: repoRoot,
       });
 
+      // 10b. Refresh yarn.lock to match the bumped versions so the release
+      //      commit stays installable under `yarn install --immutable`.
+      console.log(colorize('Updating yarn.lock...', ansi.bright));
+      await updateLockfile({cwd: repoRoot});
+
       // 11. Check if beachball actually changed anything
       const status = await git.statusPorcelain();
       if (!status) {