The board's fixed grammar keys and the menu-backed chords of
04-interactions.md § Keyboard, per the Command Nexus inventory:
- Spatial arrow navigation (NavigationMath.nearest over the marquee
registry's frames — one geometry source), walking across interior
masonry columns, lanes, and into the shown trash; ⇧-arrows extend via
the same range function as ⇧-click and go inert at the liveness and
kind boundaries; ⌥-jumps with the ⌥↑ lane-domain escalation and ↓
descent; the empty selection seeds at the first lane's first card;
selection scrolls into view.
- selectionHead — the navigation cursor beside the anchor, set by every
click, moved by every arrow, dropped by the reload vanish rule.
- Board ▸ Open Card ⌘↩ (the one command enabled mid-edit: commits the
placeholder or rename and opens), Move Up/Move Down ⌥⌘↑/⌥⌘↓
(within-lane sort, gather-then-step, rank-permuting writes in one
bracket), Move Left/Move Right ⌘←/⌘→ (sole lane, one slot, never the
trash) — all validating and acting off one shared answer.
- Delete now selects the Finder-style successor sibling from the
pre-write snapshot, so repeated ⌫ walks down a lane; external
vanishing still only shrinks the selection.
- handleReturn rejects modified Returns; the trash column renders
eagerly so every row stays registered for navigation and the marquee.
686 unit tests (27 new).
Claude-Session: https://claude.ai/code/session_01SR4XGjmBE16ZUYWpfFHXwY
