[Turbopack] Third-party import statements are not resolved in the order specified in the resolve extensions config

Link to the code that reproduces this issue

https://github.com/gabrieltrompiz/turbopack-rn-reproduction-app

To Reproduce

1. Start the application in dev mode (pnpm dev, yarn dev or npm run dev)
2. Go to localhost:3000 (or whatever port Next is using)

Current vs. Expected behavior

Current: Aliases defined in the Turbopack config are resolved in the order declared for files that are within the same repository, but does not apply that order for imports within third-party dependencies.

In the reproduction app, we import createMMKV from react-native-mmkv. That function is exported from that package by importing it from ./createMMKV/createMMKV. The aliases that I defined in the config should make it so that the import resolves to ./createMMKV/createMMKV.web.js since that takes precedence over the plain .js files (see Next config below), but Turbopack resolves to ./createMMKV/createMMKV.js which breaks the app since it contains React Native dependencies.

This is pretty much reopening https://github.com/vercel/next.js/issues/91117, but back then it was only solved for imports within your app.

Expected: The module aliases should work the same way in imports from third-party dependencies, mimicking how Webpack aliases work

Provide environment information

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 25.5.0: Tue Jun  9 22:28:24 PDT 2026; root:xnu-12377.121.10~1/RELEASE_ARM64_T6020
  Available memory (MB): 16384
  Available CPU cores: 10
Binaries:
  Node: 24.11.1
  npm: 11.6.2
  Yarn: 1.22.22
  pnpm: 10.26.2
Relevant Packages:
  next: 16.3.1-canary.24 // Latest available version is detected (16.3.1-canary.24).
  eslint-config-next: N/A
  react: 19.2.4
  react-dom: 19.2.4
  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

Next config:

const nextConfig: NextConfig = {
  turbopack: {
    resolveAlias: {
      "react-native": "react-native-web",
    },
    resolveExtensions: [
      ".web.js",
      ".web.jsx",
      ".web.ts",
      ".web.tsx",
      ".mdx",
      ".tsx",
      ".ts",
      ".jsx",
      ".js",
      ".mjs",
      ".json",
    ],
    root: __dirname,
  },

  webpack: (config) => {
    config.resolve.alias = {
      ...(config.resolve.alias || {}),
      // Transform all direct `react-native` imports to `react-native-web`
      "react-native$": "react-native-web",
    };
    config.resolve.extensions = [
      ".web.js",
      ".web.jsx",
      ".web.ts",
      ".web.tsx",
      ...config.resolve.extensions,
    ];
    return config;
  },
};

Start with the linked turbopack-rn-reproduction-app and run it in dev mode using pnpm dev, yarn dev, or npm run dev. Review the Next config's resolveAlias and resolveExtensions settings, then verify that the third-party react-native-mmkv import selects createMMKV.web.js before createMMKV.js and that the app works in next dev, next build, and next start.