[BUG] macOS Terminal.app faulty in-place updates when "Unicode East Asian Ambiguous characters are wide" theme setting is enabled

[ozziek]

Environment

• Platform (select one):
  • [x] Anthropic API
  • [ ] AWS Bedrock
  • [ ] Google Vertex AI
  • [ ] Other:
• Claude CLI version: 1.0.83 (Claude Code)
• Operating System: macOS 15.6
• Terminal: Terminal.app

Bug Description

When "Unicode East Asian Ambiguous characters are wide" is enabled, Terminal.app fails to properly display the claude code CLI. Instead of repainting the text in-place, it will continuously append the contents to the terminal.

The theme I was using had this property checked by default and it caused to CLI to be almost unusable.

Steps to Reproduce

1. Open Terminal.app
2. Enable Unicode East Asian Ambiguous characters are wide for your current theme.
   1. Settings -> Advanced -> "Unicode East Asian Ambiguous characters are wide" (at the bottom)
3. Relaunch your Terminal window
4. Run claude

Expected Behavior

The CLI updates are in place

Actual Behavior

(every keystroke a new dashed line is appended)

Additional Context

[github-actions[bot]]

Found 1 possible duplicate issue:

1. https://github.com/anthropics/claude-code/issues/5910

This issue will be automatically closed as a duplicate in 3 days.

• If your issue is a duplicate, please close it and 👍 the existing issue instead
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🤖 Generated with Claude Code

[shivrajkumar]

@ozziek Were you able to fix this for you?

[ozziek]

@shivrajkumar Yes, disabling the theme setting mentioned in the title resolved the issue for me.

[github-actions[bot]]

This issue has been inactive for 30 days. If the issue is still occurring, please comment to let us know. Otherwise, this issue will be automatically closed in 30 days for housekeeping purposes.