JSON files loaded via dynamic import() no longer trigger HMR after upgrading to 16.2

[guoxinghuang]

Link to the code that reproduces this issue

https://github.com/guoxinghuang/next-intl-hmr-repro

To Reproduce

1. Clone the repo and pnpm install
2. Run pnpm dev (uses Turbopack by default in 16.2)
3. Open http://localhost:3000
4. Edit messages/en.json (e.g., change "Hello World" to "Hello Next.js")
5. Observe: the page does not update — a full server restart is required

Current vs. Expected behavior

Current (16.2.0): Editing a JSON translation file loaded via await import(../../messages/${locale}.json) does not trigger HMR. The dev server shows no recompilation. A full restart is required to see changes.

Expected (worked in 16.1.x): Editing the same JSON file triggered HMR and the page updated automatically without a restart.

Provide environment information

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin 25.3.0

Binaries:
  Node: 22.x
  pnpm: 10.28.0

Relevant Packages:
  next: 16.2.0
  react: 19.2.4
  react-dom: 19.2.4
  next-intl: 4.8.3

Which area(s) are affected?

Turbopack, HMR

Which stage(s) are affected?

next dev (development)

Additional context

This is a regression from 16.1.x → 16.2.0. JSON translation file HMR worked correctly in 16.1.

The 16.2 Turbopack release introduced two changes that may be related:

1. Server Fast Refresh — changed from clearing the full require.cache import chain to only reloading the actually-changed module. Dynamic import() with template literal paths may not be tracked as a dependency, so dependents are not invalidated when the JSON file changes.

2. Tree Shaking of Dynamic Imports — Turbopack now tree-shakes destructured dynamic imports. This could affect how dynamic JSON imports are tracked in the module graph.

Downgrading to 16.1.x restores the expected HMR behavior.

[manthansubhash01]

Hi, I’d like to work on this issue and draft a PR.
It seems Turbopack isn’t tracking dynamic imports with template literal paths (e.g. import(../../messages/${locale}.json)), so HMR doesn’t trigger.

Planning to explore improving dependency tracking or adding a fallback invalidation. Let me know if this approach looks good.