The should_scroll_with_arrows gate was hardcoded to false since the
initial commit, which meant bare Up/Down arrows always navigated
composer history — they never scrolled the transcript view. Users in
virtual terminals (Ghostty, Codex, Kitty-protocol terminals) were
especially affected because they couldn't use the specialized Cmd+Up
/ Alt+Up shortcuts.
The gate now returns true when the composer input is empty (or
whitespace-only), so bare arrows scroll the transcript. When text
is present, arrows still navigate composer history to recall
previous prompts.
Added 3 tests covering empty, whitespace-only, and text-filled
composer states.
Hunter Bown
cc6c6c6053