[Bug] Keyboard scroll-to-bottom blanks conversation pane on >1-page jump

Bug Description
Title: Fullscreen renderer — keyboard scroll-to-bottom over a >1-page jump leaves the conversation pane blank until redraw

Environment:

• Claude Code 2.1.193 (native binary)
• macOS 26.5.1 (Tahoe), MacBook Pro M2 Max
• Ghostty 1.3.1
• Fullscreen rendering on (tui: fullscreen); NOT in tmux

Summary:
Triggering scroll:bottom via the keyboard, while scrolled up more than one page,
blanks the entire conversation pane. Input box and status line remain visible.
Deterministic.

Repro (every time):

1. Fullscreen rendering enabled.
2. Scroll up more than one page (auto-follow paused).
3. Trigger scroll:bottom via keyboard (Ctrl+End, or a custom key bound to scroll:bottom).

=> Conversation area renders blank; input + status line still shown.

Distance threshold: blanks only when the jump spans >1 page.
At <= ~half a page it never blanks.

NOT reproducible via (these always repaint correctly):

• The on-screen "Jump to bottom" button (mouse)
• Mouse-wheel scrolling to the bottom
• scroll:top (Ctrl+Home), any distance

Key-independent: reproduced identically with two different keys bound to
scroll:bottom (opt+down and ctrl+j) — so it's the action, not the key.

Does NOT fix it:

• CLAUDE_CODE_ALT_SCREEN_FULL_REPAINT=1 (no effect) — so it is not a

stale-fragment / incremental-diff artifact.

Workaround: Ctrl+L (force redraw) or typing anything repaints instantly.

Likely cause: mouse-driven scroll-to-bottom forces a frame repaint; the keyboard
scroll:bottom path does not when the jump exceeds the virtualized window, so the
viewport lands on an unpainted tail.

Environment Info

• Platform: darwin
• Terminal: ghostty
• Version: 2.1.193
• Feedback ID: 382e2909-ce83-4905-8d78-cb8c45219203

Errors

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