From a560aa90cbd7f60e55b9823b1dff009aa44d73c1 Mon Sep 17 00:00:00 2001
From: Charles Lyding <19598772+clydin@users.noreply.github.com>
Date: Tue, 14 Jul 2026 08:21:07 -0400
Subject: [PATCH 1/2] fix(@angular/cli): revert package.json changes if
 installation tasks fail during update

When running the update command, if package manager installation fails (e.g., due to peer dependency conflicts or network issues), the project's package.json is left in an updated state but node_modules is missing or inconsistent.

To prevent leaving the workspace in a broken state, backup the original package.json before applying the update plan, and restore it from the backup if the installation tasks throw an error.
---
 .../angular/cli/src/commands/update/cli.ts     | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/packages/angular/cli/src/commands/update/cli.ts b/packages/angular/cli/src/commands/update/cli.ts
index e10ff4b940b8..fc11474cc48a 100644
--- a/packages/angular/cli/src/commands/update/cli.ts
+++ b/packages/angular/cli/src/commands/update/cli.ts
@@ -541,6 +541,14 @@ export default class UpdateCommandModule extends CommandModule<UpdateCommandArgs
       return 1;
     }
 
+    const packageJsonPath = path.join(this.context.root, 'package.json');
+    let originalPackageJsonContent: string | undefined;
+    try {
+      originalPackageJsonContent = await fs.readFile(packageJsonPath, 'utf8');
+    } catch {
+      // Ignore backup errors.
+    }
+
     try {
       await applyUpdatePlan(this.context.root, plan, logger);
     } catch (error) {
@@ -596,6 +604,16 @@ export default class UpdateCommandModule extends CommandModule<UpdateCommandArgs
         Module._pathCache = Object.create(null);
       }
     } catch (e) {
+      if (originalPackageJsonContent !== undefined) {
+        try {
+          await fs.writeFile(packageJsonPath, originalPackageJsonContent, 'utf8');
+          logger.info('Restored package.json to its original state.');
+        } catch (restoreError) {
+          assertIsError(restoreError);
+          logger.error(`Failed to restore package.json: ${restoreError.message}`);
+        }
+      }
+
       if (e instanceof CommandError) {
         return 1;
       }

From 70f596497154e82de3ba33751e30c5ef7c11e18e Mon Sep 17 00:00:00 2001
From: Charles Lyding <19598772+clydin@users.noreply.github.com>
Date: Tue, 14 Jul 2026 10:41:22 -0400
Subject: [PATCH 2/2] refactor(@angular/cli): skip cleaning node_modules for
 non-npm package managers

Other package managers (pnpm, yarn, bun) deterministically reconcile node_modules with the lockfile during installation, making full directory deletion unnecessary and slow.

Keep node_modules cleanup only for npm for now.
---
 packages/angular/cli/src/commands/update/cli.ts | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/packages/angular/cli/src/commands/update/cli.ts b/packages/angular/cli/src/commands/update/cli.ts
index fc11474cc48a..b886c287f2ec 100644
--- a/packages/angular/cli/src/commands/update/cli.ts
+++ b/packages/angular/cli/src/commands/update/cli.ts
@@ -567,6 +567,11 @@ export default class UpdateCommandModule extends CommandModule<UpdateCommandArgs
     const tasks = new Listr([
       {
         title: 'Cleaning node modules directory',
+        skip() {
+          return packageManager.name !== 'npm'
+            ? 'Cleaning not required for this package manager.'
+            : false;
+        },
         async task(_, task) {
           try {
             await fs.rm(path.join(commandRoot, 'node_modules'), {