v2.1.89+ alt-screen rendering breaks scrollback and viewport on Ghostty — messages disappear, ctrl+o stops working

Environment

• Claude Code: v2.1.92 (started in v2.1.89)
• Terminal: Ghostty
• OS: macOS (Darwin 25.3.0, arm64)
• Shell: zsh

Problem

Since v2.1.89 introduced the new alt-screen / no-flicker rendering:

1. Severely limited viewport — can only see ~15 lines of chat history. Previous messages disappear from the terminal buffer entirely, not scrolled off.
2. ctrl+o (expand collapsed output) stopped working — can't expand Read/Search results inline anymore.
3. ctrl+e was broken (fixed in v2.1.92, confirmed).

The conversation becomes unusable in long sessions — you can't scroll back to see what was discussed even 5 minutes ago.

Workaround

export CLAUDE_CODE_NO_FLICKER=1 restores normal scrollback but re-enables flicker.

Expected

The alt-screen rendering should preserve terminal scrollback history. An idle-looking terminal with no history is significantly worse UX than occasional flicker.

Related

• #41814 (messages disappear after v2.1.89, 89 thumbs-up)
• #42518 (viewport jumps to top)
• #8214 (ctrl+o expand broken)