[BUG] Startup welcome box flickers then disappears on macOS (iTerm2 + Apple Terminal)

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?

The startup welcome/onboarding box (orange-bordered box with session stats) flickers briefly (~0.1-0.5s) then disappears on every launch. Only the compact header remains (pixel art logo + version + model line). This has never worked since initial setup.

~/.claude.json shows hasCompletedProjectOnboarding: true with projectOnboardingSeenCount: 0 — onboarding was auto-completed without ever being displayed. Resetting the flag does not fix it.

What Should Happen?

The orange-bordered startup welcome box should persist on screen showing session stats/onboarding info until dismissed or scrolled past.

Error Messages/Logs

No error messages. The box renders for a split second then silently vanishes.

TERM=xterm-256color, COLORTERM=truecolor, NO_COLOR/FORCE_COLOR unset.

Steps to Reproduce

1. Open any terminal (iTerm2 or Apple Terminal.app)
2. Navigate to a project directory with CLAUDE.md
3. Run claude
4. Observe: welcome box flickers briefly then vanishes
5. Only compact header remains:

Claude Code v2.1.84
Opus 4.6 (1M context) with high effort · Claude Max

Note: Reproduced in both iTerm2 and Apple Terminal.app, ruling out
terminal-specific causes. --no-alt-screen does not help.

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

Claude Code v2.1.84

Platform

Other

Operating System

macOS

Terminal/Shell

iTerm2

Additional Information

Related issues:

• #23786 — Session list flickers then disappears
• #24015 — Welcome screen flickers/disappears (Windows CLI)
• #25268 — Welcome screen stops appearing after rapid launches
• #25303 — Windows startup welcome/header not visible

Install method: native (~/.local/bin/claude)