Turbopack does not handle transpilePackages for monorepos

### Link to the code that reproduces this issue https://github.com/aulonm/nextjs-16-turbopack-monorepo-transpile-bug ### To Reproduce 1. Clone https://github.com/aulonm/nextjs-16-turbopack-monorepo-transpile-bug 2. pnpm i 3. pnpm dev 4. go to localhost:3000 Results in: <img width="410" height="209" alt="Image" src="https://github.com/user-attachments/assets/23ce6b8d-6fc7-4d9b-8701-81bad1859f8c" /> ### Current vs. Expected behavior ## Current Can't use internal monorepo packages with turbopack, it does not care about transpilePackages-property in next.config ## Expected behavior Turbopack should manage to transpile packages that are internal so that we don't need to run tsc or some kind of build system everytime we do changes to the internal packages ### Provide environment information ```bash Operating System: Platform: darwin Arch: arm64 Version: Darwin Kernel Version 25.1.0: Tue Oct 14 21:32:54 PDT 2025; root:xnu-12377.41.5~4/RELEASE_ARM64_T6041 Available memory (MB): 24576 Available CPU cores: 14 Binaries: Node: 22.13.0 npm: 10.9.0 Yarn: N/A pnpm: 10.18.3 Relevant Packages: next: 16.0.0 // Latest available version is detected (16.0.0). eslint-config-next: N/A react: 19.2.0 react-dom: 19.2.0 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) ### Additional context Adding back `--webpack` works. This is the first time we are trying out turbopack because of next@16, so not sure if this has ever worked before