Make sticky headers a reusable Screen feature and lift paging and
section jumps onto the base Screen, so every scrollable surface shares
one implementation: the frame records each render's body height and
viewport, and the shared helpers page by a screenful, clamp to the
content, and walk between the boundaries a screen records in
_sticky_headers (a select list's group dividers, the chat transcript's
day dividers).
Remap keys to match a good editor:
- PageUp/PageDown scroll by a screenful rather than a fixed step.
- Ctrl+Home/End reach the top/bottom (the live tail in chat).
- Ctrl+PageUp/PageDown jump to the current/previous and next section.
- In chat, Home/End and Ctrl+Left/Right act on the compose line; word
motion (start of current word, else previous/next) is added to the
shared line editor, so every text prompt gains it too.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Jean-Pierre MartineauandClaude Opus 4.8
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