CLAUDE_CODE_NO_FLICKER=1 causes duplicated output and garbled Unicode on Windows

Description

Setting CLAUDE_CODE_NO_FLICKER=1 in ~/.claude/settings.json env causes two rendering issues on Windows 11:

1. Duplicated output — the same text block (including tables, paragraphs) appears twice in a single response
2. Garbled Unicode — box-drawing characters render as mojibake when copy-pasting (e.g. ΓöÇΓöÇ instead of ───, Γö£ instead of ├)

Both issues disappear immediately when the env var is removed.

Steps to reproduce

1. Add "CLAUDE_CODE_NO_FLICKER": "1" to env in ~/.claude/settings.json
2. Start a new Claude Code session
3. Ask Claude to output a markdown table with Unicode box-drawing characters
4. Observe duplicated output and garbled characters when copying the response

Environment

• OS: Windows 11 Pro (10.0.26220)
• Shell: Git Bash
• Claude Code: CLI in terminal