Windows next.js EPERM

[gaojude]

For Contributors

Fixing a bug

• Related issues linked using fixes #number
  • fixes 'AGENTS.md outperforms skills in our agent evals' - compressed index is not being created in AGENTS.md vercel/next.js#89240
• Tests added. See: https://github.com/vercel/next.js/blob/canary/contributing/core/testing.md#writing-tests-for-nextjs
  • New unit tests for agents-md core logic. Existing unit tests pass.
• Errors have a helpful link attached, see https://github.com/vercel/next.js/blob/canary/contributing.md
  • N/A

For Maintainers

What?

Fixes Windows-specific issues in the agents-md codemod that prevented proper generation of the compressed documentation index.

Why?

On Windows, fs.rmSync could fail with EPERM errors due to open file handles (e.g., by git.exe), and path separators (\ vs /) were not consistently handled, leading to incomplete or failed index creation.

How?

• Implemented a removeDirSync wrapper with retry logic for EPERM, EBUSY, and ENOTEMPTY errors during directory removal.
• Updated all fs.rmSync calls in pullDocs and cloneDocsFolder to use the new robust removeDirSync.
• Normalized Windows backslashes to forward slashes in collectDocFiles for consistent path handling.

Fixes vercel#89240

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