Turbopack HMR fails on macos

Link to the code that reproduces this issue

https://github.com/ingoe/turbopack-hmr-macos-issue

To Reproduce

1. Use a Macos device
2. run npm install
3. run npm run dev
4. Edit components/problem-server-component.tsx text and save.
5. Observe whether the UI updates immediately with Turbopack
6. Edit components/working-client-component.tsx
7. Observe client component updates (this one is imported directly, so HMR should work)
8. Stop and run npm run dev:webpack
9. Repeat step 1 and compare behavior

Current vs. Expected behavior

Currently the HMR fails to update a server component which is registered using a singleton pattern registry.
Expected is HMR updates the page in the browser according to the changed source.

Provide environment information

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 25.6.0: Sat Jul 11 15:27:26 PDT 2026; root:xnu-12377.161.13~4/RELEASE_ARM64_T6031
  Available memory (MB): 65536
  Available CPU cores: 16
Binaries:
  Node: 22.21.1
  npm: 10.9.4
  Yarn: N/A
  pnpm: 10.6.5
Relevant Packages:
  next: 16.3.0 // Latest available version is detected (16.3.0).
  eslint-config-next: N/A
  react: 19.2.8
  react-dom: 19.2.8
  typescript: 5.8.3
Next.js Config:
  output: N/A

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

Turbopack

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

next dev (local)

Additional context

When using a singleton pattern to register components HMR is not updating the content in the browser when using turbopack. With webpack the issue did not happen.

Clone the reproduction at https://github.com/ingoe/turbopack-hmr-macos-issue and start with components/problem-server-component.tsx and components/working-client-component.tsx. Run npm run dev, compare server-component and client-component edits, then repeat with npm run dev:webpack. Done means the singleton-registered server component updates in the browser under Turbopack as it does with Webpack.