Non-ASCII slugs in generateStaticParams() cause errors in both dev server and build when output: "export" is set

Link to the code that reproduces this issue

https://github.com/minjongbaek/blog.minjong/tree/reproduce/non-ascii-slug-output-export

To Reproduce

1. Clone the repo and checkout reproduce/non-ascii-slug-output-export
2. Install dependencies and run the dev server (pnpm install && pnpm dev)
3. Navigate to /note/dynamic-code-evaluation-not-allowed-in-edge-runtime (ASCII slug) — works fine
4. Navigate to /note/cli-환경에서-여러-명령어를-동시에-실행하기 (non-ASCII slug)
5. Observe the error below

Current vs. Expected behavior

Current:

Dev server:

Page "/[type]/[slug]/page" is missing param "/note/cli-환경에서-여러-명령어를-동시에-실행하기" in "generateStaticParams()", which is required with "output: export" config.

Build (next build):

Error occurred prerendering page "/note/cli-환경에서-여러-명령어를-동시에-실행하기".
Error: Cannot find module './note/cli-%ED%99%98%EA%B2%BD%EC%97%90%EC%84%9C-%EC%97%AC%EB%9F%AC-%EB%AA%85%EB%A0%B9%EC%96%B4%EB%A5%BC-%EB%8F%99%EC%8B%9C%EC%97%90-%EC%8B%A4%ED%96%89%ED%95%98%EA%B8%B0/index.mdx'

Expected: Both dev server and build should handle non-ASCII slugs returned from generateStaticParams() without errors, just like ASCII slugs.

Why this happens (suspected root cause)

generateStaticParams() returns raw non-ASCII slugs (e.g. cli-환경에서-여러-명령어를-동시에-실행하기), but Next.js URL-encodes them when resolving dynamic routes. This causes a mismatch in two places:

• Dev server: compares the URL-encoded param against the raw slug → "missing param" error
• Build: tries to load the MDX module using the URL-encoded path → MODULE_NOT_FOUND

Workaround: calling decodeURIComponent(slug) inside the page component resolves the module loading issue, but the dev server still logs the "missing param" error.

Provide environment information

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 25.3.0: Wed Jan 28 20:53:15 PST 2026; root:xnu-12377.81.4~5/RELEASE_ARM64_T6000
  Available memory (MB): 16384
  Available CPU cores: 8
Binaries:
  Node: 22.14.0
  npm: 10.9.2
  Yarn: N/A
  pnpm: 10.13.1
Relevant Packages:
  next: 16.2.1-canary.16 // Latest available version is detected (16.2.1-canary.16).
  eslint-config-next: N/A
  react: 19.0.0
  react-dom: 19.0.0
  typescript: 5.8.2
Next.js Config:
  output: export

Which area(s) are affected? (Select all that apply)

Output, Dynamic Routes

Which stage(s) are affected? (Select all that apply)

next dev (local), next build (local)

Additional context

No response

Start by cloning the linked reproduction and checking out reproduce/non-ascii-slug-output-export, then run pnpm install && pnpm dev and the build command to reproduce both failures. Trace output: export handling for dynamic routes and generateStaticParams(), then verify that the non-ASCII slug works in both development and build without the reported errors.