Turbopack `resolveAlias` doesn't resolve package subpath exports for transitive dependencies

[amannn]

Link to the code that reproduces this issue

https://github.com/amannn/nextjs-bug-repro-turbo-alias

To Reproduce

git clone https://github.com/amannn/nextjs-bug-repro-turbo-alias
pnpm install
pnpm run dev
open http://localhost:3000

Relevant files:

• apps/web/next.config.ts – configures resolveAlias
• packages/wrapper-pkg/dist/index.js – re-exports from test-pkg/foo
• packages/test-pkg/package.json – defines subpath exports ./foo and ./foo/alt

Current vs. Expected behavior

	Current	Expected
Page displays	"original"	"aliased"
Module loaded	test-pkg/foo → dist/foo.js	test-pkg/foo/alt → dist/foo-alt.js

The alias works correctly when test-pkg is a direct dependency, but fails when it's a transitive dependency (nested in wrapper-pkg/node_modules).

Provide environment information

Operating System:
  Platform: darwin
  Arch: x64
  Version: Darwin Kernel Version 24.6.0: Wed Nov  5 21:30:23 PST 2025; root:xnu-11417.140.69.705.2~1/RELEASE_X86_64
  Available memory (MB): 16384
  Available CPU cores: 12
Binaries:
  Node: 22.21.1
  npm: 10.9.4
  Yarn: 1.22.22
  pnpm: 10.24.0
Relevant Packages:
  next: 16.1.1-canary.27 // Latest available version is detected (16.1.1-canary.27).
  eslint-config-next: N/A
  react: 19.2.3
  react-dom: 19.2.3
  typescript: 5.9.3
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), next build (local), next start (local)

Additional context

Workaround: use require.resolve() to get the actual file path and convert to a relative path