fix(create-app): detect the running package manager via getUserAgent

[SouichiroTsujimoto]

Summary

create-slidev currently stringifies the package manager as [object Object], then crashes with ERR_INVALID_ARG_TYPE if you choose to install immediately.

This restores getUserAgent() (the package manager that is running create-slidev) instead of detect() (lockfile lookup up the directory tree). If nothing is detected, it still falls back to npm, which is the #2703 fix for null install when the script is run with plain Node.

Background

On current create-slidev (v52.19.1), scaffolding succeeds but the follow-up install crashes:

❯ bun create slidev

  ●■▲
  Slidev Creator  v52.19.1

✔ Project name: … slidev-sample
  Scaffolding project in slidev-sample ...
  Done.

✔ Install and start it now using [object Object]? … yes
TypeError [ERR_INVALID_ARG_TYPE]: The "file" argument must be of type string. Received an instance of Object
    at normalizeSpawnArguments (node:child_process:539:3)
    at spawn (node:child_process:746:13)
    at ExecProcess.spawn (.../tinyexec/dist/main.mjs:321:18)
    at x (.../tinyexec/dist/main.mjs:404:7)
    at init (.../create-slidev/index.mjs:116:11)
    {
      code: 'ERR_INVALID_ARG_TYPE'
    }

The prompt shows [object Object]. Answering yes spawns that object as the command. Answering no prints [object Object] install / [object Object] run dev. The template is already written, so a manual bun install still works.

#2703 was meant to fix the case where running create-slidev directly with Node detects no package manager, so the later-install hints became null install / null run dev. The author, following review, used:

const pkgManager = getUserAgent() ?? 'npm'

antfu suggested that same line. A later chore: update on the PR swapped it to detect() and then used the return value as a command name. There is no note that detection should switch to lockfiles.

That produced:

• using [object Object]? in the prompt
• a crash on yes, because tinyexec tries to spawn an object
• detection of the lockfile in cwd / parents, instead of the package manager that launched create-slidev

The intent recorded in #2516 was to detect the package manager running create-slidev.

Change

packages/create-app/index.mjs only:

const pkgManager = getUserAgent() ?? 'npm'

Test plan

Verified locally:

• bun run create-slidev (or bun create slidev) shows using bun? and does not throw if you answer yes
• pnpm create slidev / npm init slidev show pnpm / npm respectively
• node packages/create-app/index.mjs with no user agent shows using npm? (fix(create-app): default manual setup to npm #2703 fallback)
• Answering no writes the real package manager name into the hints and README, not [object Object]

[netlify]

✅ Deploy Preview for slidev ready!

Name	Link
🔨 Latest commit	2dd05d5
🔍 Latest deploy log	https://app.netlify.com/projects/slidev/deploys/6a8e62b45af9fd0008d431c1
😎 Deploy Preview	https://deploy-preview-2720--slidev.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.
🤖 Make changes	Run an agent on this branch

---

To edit notification comments on pull requests, go to your Netlify project configuration.