CLAUDE_CODE_NO_FLICKER=1 causes pixelated mouse cursor on macOS

Bug Report

Environment

• OS: macOS (Darwin 25.5.0)
• Claude Code: v2.1.88
• Terminal: Terminal.app / iTerm2

Description

Setting CLAUDE_CODE_NO_FLICKER=1 in settings.json env causes the mouse cursor to become pixelated/jagged in the terminal window. The issue persists while Claude Code is running and resolves after the session ends.

Steps to Reproduce

1. Add "CLAUDE_CODE_NO_FLICKER": "1" to settings.json under the env section
2. Start a Claude Code session
3. Observe the mouse cursor — it appears pixelated/low-resolution

Expected Behavior

Mouse cursor should remain at native resolution regardless of flicker-free rendering mode.

Actual Behavior

Mouse cursor becomes pixelated, suggesting the alt-screen rendering mode may be affecting cursor compositing or display scaling.

Workaround

Remove CLAUDE_CODE_NO_FLICKER from settings (use default flicker mode).

Additional Context

The flicker-free rendering likely switches terminal rendering modes (possibly alt-screen buffer or direct screen writes), which may interfere with macOS cursor rendering in the terminal window.