Presence

Room

db.room('board', boardId) with presence fields name, color, role.

useBoardPresence:

• Boardless sessions park in per-tab idle rooms so hooks stay unconditional
• Anonymous guests get stable session colors
• Published name is shortened; never raw email

Avatars

PresenceAvatars — overlapping stack with +N overflow.

Cursors

grid-cursors.js — contentPointFromPane, gridCursorSpaceId (room-scoped key).

GridCursors:

• Publishes scroll-content coordinates (not viewport-only)
• Ignores touch pointer moves
• Republishes on pane scroll so peers stay aligned with cells
• Clears on pointer leave
• Transform + short transition + willChange