Environment

OS: Windows 11
Node.js: v24.5.0
Package Manager: pnpm
obuild version: 0.2.1

Reproduction

1. Set up a monorepo structure on Windows. (e.g., using pnpm workspaces).

   /monorepo
     /packages
       /my-lib         <-- Package to be stubbed
     /apps
       /my-nuxt-app    <-- Consuming application
   

2. Configure my-lib to use obuild for stubbing.

   packages/my-lib/package.json:

   {
     "name": "my-lib",
     "version": "1.0.0",
     "main": "./dist/index.mjs",
     "module": "./dist/index.mjs",
     "types": "./dist/index.d.mts",
     "exports": {
       ".": {
         "import": "./dist/index.mjs",
         "types": "./dist/index.d.mts"
       }
     },
     "scripts": {
       "dev": "obuild --stub"
     },
     "devDependencies": {
       "obuild": "latest"
     }
   }

   packages/my-lib/build.config.ts:

   import { defineBuildConfig } from 'obuild/config'
   
   export default defineBuildConfig({
     entries: [
       'src/index'
     ],
   })

   packages/my-lib/src/index.ts:

   export const message = "Hello from stubbed lib!";

3. Run the stub command from the root of the monorepo.

   pnpm --filter my-lib run dev

4. Inspect the generated stub file. The output file packages/my-lib/dist/index.mjs will contain an absolute Windows path:

   // packages/my-lib/dist/index.mjs
   // ⚠️ PROBLEM: This path is not a valid ESM import on Windows
   export * from "C:/Users/YourUser/Projects/monorepo/packages/my-lib/src/index.ts";

5. Attempt to use my-lib from my-nuxt-app. The Nuxt dev server will fail during module resolution.

   Error Output:

   Error: Only URLs with a scheme in: file, data, and node are supported by the default ESM loader. On Windows, absolute paths must be valid file:// URLs. Received protocol 'c:'
   ...
   code: 'ERR_UNSUPPORTED_ESM_URL_SCHEME'
   

Describe the bug

When using obuild's stub mode (obuild --stub) within a monorepo workspace on Windows, the generated stub file for a package re-exports the source code using an absolute Windows file path (e.g., C:/...).

This absolute path is not a valid file:// URL. When another package in the workspace (like a Nuxt or Vite application) tries to import from this stubbed package, Node.js's ESM loader fails with an ERR_UNSUPPORTED_ESM_URL_SCHEME error because it interprets C: as an unsupported URL protocol.

This effectively makes stub mode unusable on Windows for local development within a workspace.

Additional context

No response

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