TUI long prompt text overflows while scrolling

Description

Long prompts can render outside the expected TUI composer/message layout and cause visible flickering/overflow while using the TUI.

On opencode 1.18.31, entering a long prompt and scrolling in the TUI can make part of the prompt appear outside the expected prompt area. The long text appears to escape or clip through the layout while the composer/status area remains visible, producing visible flickering and overflow.

This appears to be a TUI layout/height-clamping or redraw issue for long wrapped prompt text while scrolling.

Plugins

@opencode-ai/plugin 1.4.6

OpenCode version

1.18.31

Steps to reproduce

1. Use opencode 1.18.31 in the TUI.
2. Paste or type a long prompt, for example several thousand characters of normal prose without manual line breaks.
3. Submit the prompt.
4. Scroll the TUI while the long prompt is in the conversation history.
5. Observe that long prompt text can visually overflow/flicker outside the expected prompt/message area instead of staying clipped within the layout.

Screenshot and/or share link

Screenshot shows long prompt text overflowing near the top of the visible TUI while the composer/status area remains at the bottom.

Operating System

macOS 26.6.2 arm64

Terminal

Ghostty (TERM=xterm-ghostty). Reproduction capture used TERM=xterm-256color with COLUMNS=80 and LINES=24.