The full pointer grammar of 04-interactions.md § Selection, stated once
as a pure function (SelectionGrammar) and reached through one store
funnel from every click surface — card face, lane header, lane empty
space, trash row:
- Plain click replaces and anchors; the lane surfaces (header and empty
space alike, per the settled one-lane-click-behavior rule) toggle off
on a sole-membership repeat.
- ⌘-click toggles within a homogeneous set; crossing any axis — cards
XOR lanes, live XOR trashed, card entries XOR lane entries in the
trash — degrades to a replace, so no click can produce a mixed
selection.
- ⇧-click ranges from the anchor in the (side, kind) order list: flatten
order for cards, lane order for lanes, the trash's deterministic sort
filtered to kind — the pointer twin of the keyboard's boundary rule
(the keyboard goes inert, the pointer skips).
- The rubber band (MarqueeSession/MarqueeMath) arms from lane empty
space, the board backdrop, and the trash column; side frozen at the
origin, trash bands homogeneous by topmost kind, frames self-registered
in strip space, geometric begin guard, never animated.
- Fast plain double-click opens the card window (⌘↩'s pointer twin);
Select All answers the standard Edit menu item via the responder
chain, trash- and kind-respecting.
- The range anchor lives in TransientBoardState beside the selection and
obeys the same reload vanish rule.
659 unit tests (28 new in SelectionGrammarTests).
Claude-Session: https://claude.ai/code/session_01SR4XGjmBE16ZUYWpfFHXwY
