[BUG] Write tool fails with EEXIST on Windows + OneDrive for longer file paths

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Describe the bug

The Write tool fails with an EEXIST error when creating files at moderately long paths (~90+ characters absolute) on Windows with
OneDrive. The error comes from the mkdirSync({recursive: true}) call that ensures the parent directory exists before writing the file.

The parent directory already exists. The mkdir call should succeed silently but instead throws EEXIST.

Affected tool

Write tool only. Read and Edit work fine on the same paths — they skip the mkdir step.

Environment

• OS: Windows 11
• Shell: cmd.exe (Windows Terminal); Claude Code internally uses Git Bash/MSYS2
• Workspace location: Inside OneDrive sync folder (C:\Users\<user>\OneDrive\...\)
• Claude Code version: Observed across multiple recent versions

Suggested fix

Catch EEXIST from the mkdir call in the Write tool and continue — the directory existing is the success case, not an error. Something
like:

try {
fs.mkdirSync(parentDir, { recursive: true });
} catch (err) {
if (err.code !== 'EEXIST') throw err;
}

Workaround

Write to a short temp path (e.g. C:/tmp/file.ext) then move the file to the real location via Bash mv.

Related but distinct issues

• #31185, #30960, #30924, #31030 — EEXIST during startup on config/auth paths (different codepath, same underlying Node.js bug)
• #29153 — OneDrive .claude.json corruption (different symptom)

What Should Happen?

Expected behavior

mkdirSync(parentDir, {recursive: true}) should succeed silently when the directory already exists, as documented in the Node.js API.

Actual behavior

The call throws EEXIST. This appears to be a known Node.js edge case on Windows where recursive: true mkdir can throw EEXIST instead of
succeeding, exacerbated by OneDrive's file system overlay (reparse points / cloud placeholders).

Error Messages/Logs

EEXIST: file already exists, mkdir

Steps to Reproduce

1. Run Claude Code from a workspace inside an OneDrive-synced directory with a moderately long base path
2. Ask Claude to write a file where the absolute path is ~90+ characters (e.g. C:\Users\<user>\OneDrive\Personal\AI

workspace\projects\some-project\workflows\some-file.md)

1. The parent directory already exists
2. Write tool fails with EEXIST: file already exists, mkdir

Claude Model

Opus

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

2.1.71

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

_No response_