[BUG] Fullscreen TUI mode silently captures all mouse events, breaking native terminal copy/paste

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?

Setting "tui": "fullscreen" in settings.json (or opting into fullscreen mode)
captures ALL mouse events (click, drag, wheel) via SGR mouse tracking in the
alternate screen buffer. This breaks native terminal copy (drag-select) and
paste (right-click / Ctrl+V) — the terminal's own selection/paste only works

There is no warning when enabling fullscreen mode that this will happen, and
the mitigation env vars (CLAUDE_CODE_DISABLE_MOUSE,
CLAUDE_CODE_DISABLE_MOUSE_CLICKS) are hard to discover — I had to dig through
docs/support to find them, and initially set the wrong one
(CLAUDE_CODE_DISABLE_MOUSE_CLICKS only disables click/drag, not wheel capture,
so Shift was still required).

Suggestions:

• Show a one-time warning/tip when fullscreen mode is enabled, mentioning the

copy/paste tradeoff and the exact env var to fix it if desired.

• Document CLAUDE_CODE_DISABLE_MOUSE and CLAUDE_CODE_DISABLE_MOUSE_CLICKS

clearly next to the "tui" setting docs, since they're easy to confuse.

Environment: Linux, X11, GNOME Terminal (TERM=xterm-256color)

What Should Happen?

Enabling fullscreen mode should either:
1) Show a one-time warning/tip explaining that mouse capture will intercept
clicks/drag/wheel, breaking native terminal copy-paste unless Shift is held or
CLAUDE_CODE_DISABLE_MOUSE is set, or
2) Document the tradeoff and the exact env vars (CLAUDE_CODE_DISABLE_MOUSE vs
CLAUDE_CODE_DISABLE_MOUSE_CLICKS) directly next to the "tui" setting in the
settings.json docs, so users don't have to guess or trial-and-error which var
actually fixes it.

Error Messages/Logs

Steps to Reproduce

1. Add "tui": "fullscreen" to ~/.claude/settings.json (or otherwise enable

fullscreen TUI mode)

1. Restart Claude Code
2. Try to select text with mouse drag, or paste with right-click / Ctrl+V in

the terminal

1. Notice normal copy/paste doesn't work — only Shift+drag / Shift+right-click

bypass the app's mouse capture

1. Mouse wheel scrolling is also captured by the app instead of the terminal's

native scrollback

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.197

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Other

Additional Information

_No response_