Require explicit package manager for project operations

packages/app/src/cli/models/app/app.test-data.ts

@@ -82,7 +82,8 @@ import {Project} from '../project/project.js'
 import {Session} from '@shopify/cli-kit/node/session'
 import {vi} from 'vitest'
 import {joinPath} from '@shopify/cli-kit/node/path'
-import {PackageManager} from '@shopify/cli-kit/node/node-package-manager'
+import {ProjectPackageManager} from '@shopify/cli-kit/node/node-package-manager'
+import {AbortError} from '@shopify/cli-kit/node/error'
 
 export const DEFAULT_CONFIG = {
   application_url: 'https://myapp.com',
@@ -154,7 +155,7 @@ export function testAppWithConfig(options?: TestAppWithConfigOptions): AppLinked
 
 interface TestProjectOptions {
   directory?: string
-  packageManager?: PackageManager
+  packageManager?: ProjectPackageManager | 'unknown'
   nodeDependencies?: Record<string, string>
   usesWorkspaces?: boolean
 }
@@ -164,9 +165,11 @@ interface TestProjectOptions {
  * Use this when a service needs a Project for packageManager, usesWorkspaces, or directory.
  */
 export function testProject(options: TestProjectOptions = {}): Project {
+  const packageManager = options.packageManager ?? 'yarn'
+
   return {
     directory: options.directory ?? '/tmp/project',
-    packageManager: options.packageManager ?? 'yarn',
+    packageManager,
     nodeDependencies: options.nodeDependencies ?? {},
     usesWorkspaces: options.usesWorkspaces ?? false,
     appConfigFiles: [],
@@ -177,6 +180,13 @@ export function testProject(options: TestProjectOptions = {}): Project {
     appConfigByName: () => undefined,
     appConfigByClientId: () => undefined,
     defaultAppConfig: undefined,
+    requirePackageManagerForOperations: () => {
+      if (packageManager === 'unknown') {
+        throw new AbortError('Could not determine the project package manager.')
+      }
+
+      return packageManager
+    },
   } as unknown as Project
 }
 

packages/app/src/cli/models/project/project-integration.test.ts

@@ -212,6 +212,19 @@ describe('Project integration', () => {
     })
   })
 
+  test('Project.requirePackageManagerForOperations errors when the app root has no package.json', async () => {
+    await inTemporaryDirectory(async (dir) => {
+      await setupRealApp(dir)
+      await removeFile(joinPath(dir, 'package.json'))
+
+      const project = await Project.load(dir)
+
+      expect(() => project.requirePackageManagerForOperations()).toThrow(
+        /Could not determine the project package manager/,
+      )
+    })
+  })
+
   test('multi-config project discovers all configs', async () => {
     await inTemporaryDirectory(async (dir) => {
       await setupRealApp(dir)

packages/app/src/cli/models/project/project.ts

@@ -157,6 +157,20 @@ export class Project {
   get defaultAppConfig(): TomlFile | undefined {
     return this.appConfigByName(configurationFileNames.app)
   }
+
+  /**
+   * Returns the project package manager for install/mutation operations.
+   * Throws when the app root has no package.json and the package manager is therefore unknown.
+   */
+  requirePackageManagerForOperations(): ProjectPackageManager {
+    if (this.packageManager === 'unknown') {
+      throw new AbortError(
+        `Could not determine the project package manager for ${this.directory}. Add a package.json to the app root before running dependency operations.`,
+      )
+    }
+
+    return this.packageManager
+  }
 }
 
 // ── Filesystem discovery functions ──────────────────────────

packages/app/src/cli/services/dependencies.test.ts

@@ -28,4 +28,16 @@ describe('installAppDependencies', () => {
       deep: 3,
     })
   })
+
+  test('errors before install when the project package manager is unknown', async () => {
+    const project = testProject({packageManager: 'unknown', directory: '/tmp/project'})
+
+    await installAppDependencies(project)
+
+    const tasks = vi.mocked(renderTasks).mock.calls[0]![0] as any
+    const task = tasks[0]
+
+    await expect(task.task()).rejects.toThrow(/Could not determine the project package manager/)
+    expect(installNPMDependenciesRecursively).not.toHaveBeenCalled()
+  })
 })

packages/app/src/cli/services/dependencies.ts

@@ -14,7 +14,7 @@ export async function installAppDependencies(project: Project) {
       title: 'Installing dependencies',
       task: async () => {
         await installNPMDependenciesRecursively({
-          packageManager: project.packageManager,
+          packageManager: project.requirePackageManagerForOperations(),
           directory: project.directory,
           deep: 3,
         })

packages/app/src/cli/services/generate/extension.test.ts

@@ -11,6 +11,7 @@ import * as functionBuild from '../function/build.js'
 import {
   checkoutUITemplate,
   testDeveloperPlatformClient,
+  testProject,
   testRemoteExtensionTemplates,
 } from '../../models/app/app.test-data.js'
 import {ExtensionTemplate} from '../../models/app/template.js'
@@ -91,6 +92,29 @@ describe('initialize a extension', async () => {
     })
   })
 
+  test('errors before installing extension dependencies when the project package manager is unknown', async () => {
+    await withTemporaryApp(async (tmpDir) => {
+      const app = (await loadApp({
+        directory: tmpDir,
+        specifications,
+        userProvidedConfigName: undefined,
+      })) as AppLinkedInterface
+
+      const result = generateExtensionTemplate({
+        extensionTemplate: checkoutUITemplate,
+        app,
+        project: testProject({directory: tmpDir, packageManager: 'unknown'}),
+        extensionChoices: {name: 'extension-name', flavor: 'vanilla-js'},
+        developerPlatformClient: testDeveloperPlatformClient(),
+        onGetTemplateRepository,
+      })
+
+      await expect(result).rejects.toThrow(/Could not determine the project package manager/)
+      expect(vi.mocked(installNodeModules)).not.toHaveBeenCalled()
+      expect(vi.mocked(addNPMDependenciesIfNeeded)).not.toHaveBeenCalled()
+    })
+  })
+
   test('successfully generates the extension when another extension exists', async () => {
     await withTemporaryApp(async (tmpDir) => {
       const name1 = 'my-ext-1'

packages/app/src/cli/services/generate/extension.ts

@@ -190,14 +190,16 @@ async function functionExtensionInit({
     taskList.push({
       title: 'Installing additional dependencies',
       task: async () => {
+        const packageManager = project.requirePackageManagerForOperations()
+
         // We need to run install once to setup the workspace correctly
         if (project.usesWorkspaces) {
-          await installNodeModules({packageManager: project.packageManager, directory: project.directory})
+          await installNodeModules({packageManager, directory: project.directory})
         }
 
         const requiredDependencies = getFunctionRuntimeDependencies(templateLanguage)
         await addNPMDependenciesIfNeeded(requiredDependencies, {
-          packageManager: project.packageManager,
+          packageManager,
           type: 'prod',
           directory: project.usesWorkspaces ? directory : project.directory,
         })
@@ -258,7 +260,7 @@ async function uiExtensionInit({
     {
       title: 'Installing dependencies',
       task: async () => {
-        const packageManager = project.packageManager
+        const packageManager = project.requirePackageManagerForOperations()
         if (project.usesWorkspaces) {
           // Only install dependencies if the extension is javascript
           if (getTemplateLanguage(extensionFlavor?.value) === 'javascript') {