BiDi rendering bug in Co-Work: Hebrew + English mixed text appears in wrong visual order

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?

In Claude Desktop Co-Work, when Claude writes a response that mixes Hebrew (RTL) text with English terms, the text appears in the wrong visual order — making it completely unreadable for Hebrew-speaking users.

Expected behavior: "המודולה הבאה היא [Concept Learning] שעוסקת בהבחנה"
(Hebrew sentence with English term in the correct position)

Actual behavior: The English words and Hebrew words appear in reversed or scrambled visual order.

What was tested (all failed in Co-Work):

• Unicode isolation characters U+2066 (LRI) / U+2069 (PDI) around English terms
• Inline backticks for English terms
• HTML <span dir="ltr"> around English terms
• Pure Hebrew text (no English): works correctly
• Code blocks: work correctly

Important note: The LRI/PDI approach DOES work correctly in Claude Code (terminal). The bug is specific to Co-Work's markdown renderer.

This is a significant accessibility issue for Hebrew-speaking users working with technical content, as any mix of Hebrew and English becomes unreadable.

What Should Happen?

Hebrew text mixed with English terms should render correctly in Co-Work's UI — the same way it works in Claude Code's terminal. The BiDi algorithm should preserve the correct visual order so that Hebrew-speaking users can read the output.

Error Messages/Logs

Steps to Reproduce

1. Open Claude Desktop and start a Co-Work session
2. Ask Claude to write any sentence in Hebrew that contains an English technical term (e.g., "explain what Concept Learning is")
3. Observe the response — Hebrew and English words appear in wrong visual order

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Claude Desktop Co-Work (latest)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_