yoi/.yoi/tickets/closed/20260529-010200-tui-composer-cursor-scroll/item.md

id	slug	title	status	kind	priority	labels	created_at	updated_at	assignee
20260529-010200-tui-composer-cursor-scroll	tui-composer-cursor-scroll	Scroll TUI composer around cursor	closed	task	P2	tui input ux	2026-05-29T01:02:00Z	2026-05-29T02:08:04Z	null

Background

The TUI composer/input area has a fixed visible height. When the input buffer grows beyond the visible area (for example 10+ lines), the rendered text is clipped instead of scrolling to keep the cursor visible.

This makes editing long messages unreliable: the user can continue typing or moving the cursor, but the relevant lines may be outside the visible area.

Requirements

• Implement cursor-based vertical scrolling for the normal composer input area.
• The visible viewport should follow the cursor line when the input has more lines than the allocated input height.
  • Moving the cursor above the viewport scrolls up.
  • Moving the cursor below the viewport scrolls down.
  • Typing new lines at the bottom keeps the cursor visible.
  • Deleting lines clamps the scroll offset to valid bounds.
• Preserve existing input behavior:
  • editing operations.
  • cursor movement.
  • selection/completion behavior for file refs if applicable.
  • queued input behavior.
  • command mode behavior unless command input shares the same rendering path and needs the same fix.
• The cursor's terminal position should correspond to the visible cursor location after scrolling.
• The implementation should not simply increase composer height or hide conversation content indefinitely.
• Keep visual separators/borders consistent with the existing TUI layout.

Acceptance criteria

• A composer buffer longer than the visible input area renders a window around the cursor instead of clipping from a fixed origin.
• Cursor up/down/page movement updates the composer viewport correctly.
• Inserting/deleting lines keeps viewport bounds valid.
• Existing short single-line and small multi-line input rendering remains unchanged.
• Focused tests cover viewport calculation around cursor position and clamping.
• cargo fmt --check
• Relevant TUI focused tests, e.g. cargo test -p tui input --no-default-features or equivalent.
• cargo check -p tui

Out of scope

• Resizable composer UX redesign.
• Mouse scrolling inside composer.
• Horizontal scrolling/wrapping redesign beyond what is needed to keep current behavior correct.
• Changing command completion behavior; see 20260529-010200-tui-command-completion-apply.