angular
diff --git a/packages/angular/cli/src/commands/add/cli.ts b/packages/angular/cli/src/commands/add/cli.ts
@@ -224,29 +224,12 @@ export default class AddCommandModule
         {
           title: 'Confirming installation',
           enabled: !skipConfirmation && !options.dryRun,
-          skip: (context) => {
-            if (context.hasSchematics) {
-              return false;
-            }
-
-            return `The ${color.blue(context.packageIdentifier.toString())} package does not provide \`ng add\` actions.`;
-          },
           task: (context, task) => this.confirmInstallationTask(context, task),
           rendererOptions: { persistentOutput: true },
         },
         {
           title: 'Installing package',
           skip: (context) => {
-            if (!context.hasSchematics) {
-              const builtInSchematic =
-                BUILT_IN_SCHEMATICS[
-                  context.packageIdentifier.name as keyof typeof BUILT_IN_SCHEMATICS
-                ];
-              if (builtInSchematic) {
-                return `Skipping package installation.`;
-              }
-            }
-
             if (context.dryRun) {
               return `Skipping package installation. Would install package ${color.blue(
                 context.packageIdentifier.toString(),
@@ -278,6 +261,9 @@ export default class AddCommandModule
               if (localManifest['ng-add']?.save === false) {
                 shouldCleanUp = true;
               }
+            } else {
+              await this.cleanUpTemporaryDependency(result.collectionName);
+              shouldCleanUp = false;
             }
           } catch {}
         }
@@ -305,6 +291,9 @@ export default class AddCommandModule
           const builtInSchematic =
             BUILT_IN_SCHEMATICS[packageName as keyof typeof BUILT_IN_SCHEMATICS];
           if (builtInSchematic) {
+            logger.info(
+              `The ${color.blue(packageName)} package does not provide \`ng add\` actions.`,
+            );
             logger.info('The Angular CLI will use built-in actions to add it to your project.');
 
             return this.executeSchematic({

diff --git a/packages/angular/cli/src/commands/update/cli.ts b/packages/angular/cli/src/commands/update/cli.ts
@@ -634,7 +634,7 @@ export default class UpdateCommandModule extends CommandModule<UpdateCommandArgs
       }
     }
 
-    const migrations = plan.migrationsToRun;
+    const migrations = await resolveFallbackMigrations(this.context.root, plan);
 
     if (migrations) {
       for (const migration of migrations) {
@@ -706,3 +706,49 @@ async function readPackageManifest(manifestPath: string): Promise<PackageManifes
     return undefined;
   }
 }
+
+/**
+ * Resolves migrations from installed package manifests on disk when they were omitted
+ * from the initial update plan.
+ *
+ * This fallback is necessary because private package registries (such as GitHub Packages)
+ * frequently strip custom non-npm metadata properties (like `ng-update`) from their remote
+ * registry API responses. By inspecting `node_modules/<package>/package.json` after installation,
+ * we ensure that any migration collections defined by the package are discovered and queued.
+ */
+export async function resolveFallbackMigrations(
+  workspaceRoot: string,
+  plan: UpdatePlan,
+): Promise<{ package: string; collection: string; from: string; to: string }[]> {
+  const migrations = [...plan.migrationsToRun];
+  const existingMigrationPackages = new Set(migrations.map((m) => m.package));
+
+  for (const [packageName, targetVersion] of plan.packagesToUpdate) {
+    if (existingMigrationPackages.has(packageName)) {
+      continue;
+    }
+
+    const packageJsonPath = findPackageJson(workspaceRoot, packageName);
+    if (packageJsonPath) {
+      try {
+        const packageJson = JSON.parse(await fs.readFile(packageJsonPath, 'utf8'));
+        const ngUpdate = packageJson?.['ng-update'];
+        if (ngUpdate && typeof ngUpdate === 'object' && typeof ngUpdate.migrations === 'string') {
+          const installedVersion = plan.packageInfoMap.get(packageName)?.installed.version;
+          if (installedVersion) {
+            migrations.push({
+              package: packageName,
+              collection: ngUpdate.migrations,
+              from: installedVersion,
+              to: targetVersion,
+            });
+          }
+        }
+      } catch {
+        // Ignore read/parse errors for optional fallback
+      }
+    }
+  }
+
+  return migrations;
+}
diff --git a/packages/angular/cli/src/commands/update/cli_spec.ts b/packages/angular/cli/src/commands/update/cli_spec.ts
@@ -0,0 +1,133 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.dev/license
+ */
+
+import assert from 'node:assert';
+import { mkdir, mkdtemp, rm, writeFile } from 'node:fs/promises';
+import path from 'path';
+import { resolveFallbackMigrations } from './cli';
+import type { PackageVersionInfo, UpdatePlan } from './update-resolver';
+
+describe('resolveFallbackMigrations', () => {
+  let tempRoot: string;
+  let pkgDir: string;
+  beforeEach(async () => {
+    const baseTmpDir = process.env['TEST_TMPDIR'];
+    assert(baseTmpDir, 'TEST_TMPDIR is not set');
+    tempRoot = await mkdtemp(path.join(baseTmpDir, 'angular-cli-update-cli-test-'));
+    pkgDir = path.join(tempRoot, 'node_modules/@company/library-name');
+    await mkdir(pkgDir, { recursive: true });
+  });
+
+  afterEach(async () => {
+    await rm(tempRoot, { recursive: true, force: true });
+  });
+
+  it('discovers migrations from installed package.json when omitted from plan.migrationsToRun', async () => {
+    await writeFile(
+      path.join(pkgDir, 'package.json'),
+      JSON.stringify({
+        name: '@company/library-name',
+        version: '21.2.0-next.1',
+        'ng-update': {
+          migrations: './schematics/migration.json',
+        },
+      }),
+      'utf8',
+    );
+
+    const plan: UpdatePlan = {
+      packagesToUpdate: new Map([['@company/library-name', '21.2.0-next.1']]),
+      migrationsToRun: [],
+      packageInfoMap: new Map([
+        [
+          '@company/library-name',
+          {
+            name: '@company/library-name',
+            npmPackageJson: {
+              name: '@company/library-name',
+              versions: ['21.1.0', '21.2.0-next.1'],
+              'dist-tags': {},
+            },
+            installed: {
+              version: '21.1.0' as unknown as PackageVersionInfo['version'],
+              packageJson: { name: '@company/library-name', version: '21.1.0' },
+              updateMetadata: { packageGroup: {}, requirements: {} },
+            },
+            packageJsonRange: '^21.1.0',
+          },
+        ],
+      ]),
+      registryClient: undefined as unknown as UpdatePlan['registryClient'],
+    };
+
+    const migrations = await resolveFallbackMigrations(tempRoot, plan);
+
+    expect(migrations).toEqual([
+      {
+        package: '@company/library-name',
+        collection: './schematics/migration.json',
+        from: '21.1.0',
+        to: '21.2.0-next.1',
+      },
+    ]);
+  });
+
+  it('does not duplicate migration if package is already in plan.migrationsToRun', async () => {
+    await writeFile(
+      path.join(pkgDir, 'package.json'),
+      JSON.stringify({
+        name: '@company/library-name',
+        version: '21.2.0-next.1',
+        'ng-update': {
+          migrations: './schematics/migration.json',
+        },
+      }),
+      'utf8',
+    );
+
+    const plan: UpdatePlan = {
+      packagesToUpdate: new Map([['@company/library-name', '21.2.0-next.1']]),
+      migrationsToRun: [
+        {
+          package: '@company/library-name',
+          collection: './schematics/migration.json',
+          from: '21.1.0',
+          to: '21.2.0-next.1',
+        },
+      ],
+      packageInfoMap: new Map(),
+      registryClient: undefined as unknown as UpdatePlan['registryClient'],
+    };
+
+    const migrations = await resolveFallbackMigrations(tempRoot, plan);
+
+    expect(migrations).toHaveSize(1);
+  });
+
+  it('returns unchanged migrations when package has no ng-update field on disk', async () => {
+    await writeFile(
+      path.join(pkgDir, 'package.json'),
+      JSON.stringify({
+        name: '@company/library-name',
+        version: '21.2.0-next.1',
+      }),
+      'utf8',
+    );
+
+    const plan: UpdatePlan = {
+      packagesToUpdate: new Map([['@company/library-name', '21.2.0-next.1']]),
+      migrationsToRun: [],
+      packageInfoMap: new Map(),
+      registryClient: undefined as unknown as UpdatePlan['registryClient'],
+    };
+
+    const migrations = await resolveFallbackMigrations(tempRoot, plan);
+
+    expect(migrations).toHaveSize(0);
+  });
+});