Reader fails in Dynamic Route inside app router root directory on production

[bastienrobert]

When trying to use the Keystatic reader to fetch content within a dynamic route under the app/ directory, the reader does not function as expected.
This issue occurs specifically when the route is dynamic ([slug], [id], etc.), and the Keystatic reader is called to fetch content dynamically based on the route parameters.

Steps to Reproduce:

1. Set up a Next.js project using the app/ directory structure.
2. Install and configure Keystatic to manage static content (e.g., Markdown files).
3. Create a dynamic route, such as app/[slug]/page.tsx, and call the Keystatic reader inside it to fetch content based on the slug.
4. Try accessing the route with different dynamic values (/post-1, /post-2, etc.).

• https://nextjs-keystatic-test-params-repro.vercel.app/ (WORKING EXEMPLE)
• https://nextjs-keystatic-test-params-repro.vercel.app/fr (SAME CODE BUT IN app/[locale])

REPO
https://github.com/bastienrobert/nextjs-keystatic-test-params-repro

Workaround:
Dynamic import using the standard import() method, put every mdx and markdoc inline and format files to JSON.

[brooksbecton]

I'm not so sure if it is a bug with keystatic or nextjs.
Maybe just innaccurate docs

If you follow the docs as is right now. The single collection example will be a dynamic route in NextJS.
To fix this issue, you'll need to statically render that single collection with the generateStaticParams

You can do that in Next 14 with

export async function generateStaticParams() {
  const posts = await reader.collections.posts.all();

  return posts.map((post) => ({ slug: post.slug }));
}

So maybe this part needs to be updated
https://keystatic.com/docs/installation-next-js#displaying-a-single-collection-entry