[BUG] rxvt-unicode with tui: fullscreen always append mouse selection instead of replacing #109196

Preflight Checklist

• I have searched existing issues and this hasn't been reported yet
• This is a single bug report (please file separate reports for different bugs)
• I am using the latest version of Claude Code

What's Wrong?

In linux, using rxvt-unicode and claude with tui: fullscreen, when i select text, it copies the text, but if i keep selecting text, it just append. After hours of working, by copy&paster buffer can have multiple pages of copied text. selecting text in any other app will copy that text only, but returning to claude and selecting one word, it will add again everything ever selected in claude. If i do shift+mouse select, it works normally, using the X11 Primary buffer . With normal TUI, the X11 Primary buffer also works fine

What Should Happen?

if i select a text, it should clear existent data in claude copy&paste buffer and replace with the select text, not append to it

Error Messages/Logs

Steps to Reproduce

Install rxvt-unicode (ubuntu 24.04)
open rxvt
start claude
configure TUI to fullscreen
type hello
select some text. It should work
select now another text in claude, it should have the first text and the new selected text appended

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

No response

Claude Code Version

rxvt-unicode

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Other

Additional Information

No response