EEXIST: file already exists, mkdir when Edit tool updates files in existing directories on Windows

Environment

• OS: Windows 11 Pro
• Claude Code version: 2.1.69
• Shell: Git Bash (bash)

Description
When the Edit tool attempts to update an existing file (e.g. app/page.tsx in a Next.js project), Claude Code tries to mkdir the parent directory even though it already exists. On Windows, this throws EEXIST: file already exists, mkdir '<path>' instead of silently continuing.

Repro

1. Open a Next.js project on Windows where app/ directory exists
2. Ask Claude to edit app/page.tsx
3. Edit tool fails with: Error: EEXIST: file already exists, mkdir 'C:\path\to\project\app'

Expected behaviour
Edit tool should handle the case where the parent directory already exists (skip mkdir or use mkdir -p equivalent).

Workaround
None at the model level — Claude falls back to Bash scripts which may also fail depending on environment.