[BUG] skill-creator: run_loop.py crashes on Windows with UnicodeEncodeError on HTML report

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?

run_loop.py calls path.write_text(html) without specifying encoding="utf-8". On Windows the default encoding is cp1252, which cannot encode characters like ✗ (U+2717) used in the HTML report.

What Should Happen?

All write_text() calls in run_loop.py should explicitly pass encoding="utf-8".

Error Messages/Logs

Steps to Reproduce

1. Run run_loop.py on Windows (even after fixing WinError 10038)
2. After the first evaluation pass, the script tries to write the live HTML report
3. Error: UnicodeEncodeError: 'charmap' codec can't encode character '\u2717' in position 9725
4. Script crashes, no results saved

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.92

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

Windows 11 Pro 10.0.26200