[BUG] Bash tool corrupts Cyrillic (UTF-8) characters in curl requests on Windows

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?

Description:

Environment:

• OS: Windows 10/11
• Claude Code version: [ваша версия]
• Shell: Git Bash / WSL

Problem:
When using the Bash tool to execute curl commands with Cyrillic (UTF-8) text in JSON payload, characters are
corrupted into mojibake.

Example:

curl -X POST http://example.com/api \
-H "Content-Type: application/json; charset=utf-8" \
-d '{"text": "Привет мир"}'

Expected result in database:
"Привет мир"

Actual result:
"������ ���"

Workaround:
PowerShell handles UTF-8 correctly:
powershell.exe -File script.ps1

Request:
Please fix UTF-8 encoding in Bash tool for Windows, or provide automatic detection to use PowerShell when
Cyrillic/UTF-8 characters are detected in curl payloads.

Impact:
This forces Claude to either:

1. Write all database content in English (bad UX for non-English users)
2. Manually use PowerShell workarounds (inefficient)
3. Corrupt data with mojibake (unacceptable)

This issue persists for 2+ months and severely impacts usability for Cyrillic users.

What Should Happen?

Description:

Environment:

• OS: Windows 10/11
• Claude Code version: [ваша версия]
• Shell: Git Bash / WSL

Problem:
When using the Bash tool to execute curl commands with Cyrillic (UTF-8) text in JSON payload, characters are
corrupted into mojibake.

Example:

curl -X POST http://example.com/api \
-H "Content-Type: application/json; charset=utf-8" \
-d '{"text": "Привет мир"}'

Expected result in database:
"Привет мир"

Actual result:
"������ ���"

Workaround:
PowerShell handles UTF-8 correctly:
powershell.exe -File script.ps1

Request:
Please fix UTF-8 encoding in Bash tool for Windows, or provide automatic detection to use PowerShell when
Cyrillic/UTF-8 characters are detected in curl payloads.

Impact:
This forces Claude to either:

1. Write all database content in English (bad UX for non-English users)
2. Manually use PowerShell workarounds (inefficient)
3. Corrupt data with mojibake (unacceptable)

This issue persists for 2+ months and severely impacts usability for Cyrillic users.

Note to developers:
I don't want to spend my time debugging YOUR product, filling out forms, and hunting down your bugs. This is a
critical encoding issue that should have been caught in testing. Fix it.

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Error Messages/Logs

Steps to Reproduce

...

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

...

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_