[BUG] Word wrap is broken: breaks mid-word instead of at word boundaries

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

Text output in Claude Code is splitting words mid-character at the terminal edge instead of wrapping whole words to the next line.

Specific version where this broke appears to be 2.0.73. See below thread for screenshots showing that this was working in 2.0.72.

This bug is still present in 2.1.1 as of Jan 8 2026.

Expected behavior

Words wrap to the next line at word boundaries (spaces), keeping words intact.

Actual behavior

Words are split mid-character when they reach the terminal edge. For example, "not" becomes "no" at the end of one line and "t" at the start of the next.

Environment

• macOS Terminal.app, Ghostty (Mac), Zed (Mac), Nova (Mac)
• macOS version: 15.7.2
• Claude Code version: 2.0.76, 2.1.1

Screenshots

Previously working:
<img width="1269" height="56" alt="Image" src="https://github.com/user-attachments/assets/f1277c6e-9f6d-4ba1-856b-345eef1eb359" />

No longer working:
<img width="1268" height="116" alt="Image" src="https://github.com/user-attachments/assets/a015377b-aed5-409f-a0f6-ab3f2855d9c9" />

Notes

This previously worked correctly. The issue appears to be a regression.

What Should Happen?

Words should wrap properly when they hit the right edge of the terminal window

Error Messages/Logs

Steps to Reproduce

1. Open macOS Terminal.app
2. Set terminal width to 140 columns
3. Run claude
4. Ask any question that produces a response longer than the terminal width
5. Observe words being split mid-character at the right edge

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.0.76

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_