Turbopack applies internal asset path prefix for assets that get imported to manifest file

[dlehmhus]

Link to the code that reproduces this issue

https://github.com/dlehmhus/turbopack-webmanifest-assets-bug

To Reproduce

1. Start the application in development (npm run dev)
2. Visit http://localhost:3000/manifest.webmanifest
3. Try to request the referenced png file

Current vs. Expected behavior

Current

All assets imported in the manifest.ts get a 404 response when requested from the client.

Expected
All assets from the manifest.ts file should get served.

Provide environment information

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 24.5.0: Tue Apr 22 19:54:49 PDT 2025; root:xnu-11417.121.6~2/RELEASE_ARM64_T6000
  Available memory (MB): 16384
  Available CPU cores: 10
Binaries:
  Node: 22.11.0
  npm: 10.9.0
  Yarn: 1.22.19
  pnpm: N/A
Relevant Packages:
  next: 15.4.0-canary.83 // Latest available version is detected (15.4.0-canary.83).
  eslint-config-next: N/A
  react: 19.1.0
  react-dom: 19.1.0
  typescript: 5.8.3
Next.js Config:
  output: N/A

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

Turbopack, Metadata

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

next dev (local)

Additional context

Currently, the manifest.webmanifest contains URLs to assets that look like:

{  "src": "/server/assets/icon.3dd39a76.png" }

Based on the way it works in webpack, it should look like:

{  "src": "/_next/static/media/icon.3dd39a76.png" }

_PACK-4874

[dlehmhus]

Update: the same issue also applies to assets imported into api routes.