installNodeModules() uses wrong subcommand for yarn/pnpm when adding specific packages

[umxr]

Problem

installNodeModules() in packages/cli-kit/src/public/node/node-package-manager.ts always runs <pm> install <packages>, but yarn and pnpm require add instead of install when adding specific packages with version specifiers.

This caused hydrogen upgrade to fail on yarn projects, and would similarly fail on pnpm.

Current behavior

let args = ['install']
if (options.args) {
  args = args.concat(options.args)
}
await exec(options.packageManager, args, execOptions)

This produces commands like:

• yarn install @shopify/hydrogen@2025.7.1 — fails (install has been replaced with add)
• pnpm install @shopify/hydrogen@2025.7.1 — fails (pnpm install installs from lockfile, not specific packages)

Expected behavior

When specific packages are passed via args, the correct subcommand should be used per package manager:

Package Manager	Correct Subcommand
npm	install
yarn	add
pnpm	add
bun	install

Workaround

Shopify/hydrogen#3462 bypassed installNodeModules() with a direct exec() call that maps the correct subcommand per package manager. Once this upstream fix lands, that workaround can be removed.

References

• Hydrogen PR with workaround: Fix hydrogen upgrade failing with yarn hydrogen#3462
• Review comment requesting this issue: Fix hydrogen upgrade failing with yarn hydrogen#3462 (comment)

[umxr]

I authored the workaround for this in Shopify/hydrogen#3462 and would like to submit the upstream fix here as well. Happy to open a PR once this is greenlit.