TransientBoardState, one per store, holds state by how a reload treats
it: item-referencing sets (selection, drag membership, pending cut)
share one shape and one constraint rule — members must exist in the
current universe — applied in two directions by one primitive, so the
search filter's hidden-cards rule and reload survival are one rule
expressed once; derived state is stored as its inputs only (the query,
never its result set); and the new-card placeholder is a lane-anchored
overlay with no UUID until commit, discarded when its lane vanishes or
tombstones, handed off when the created card's UUID appears. Trash
visibility rides along per-open, never persisted. The decision is
written back into DESIGN/02 § Changes from Kanban — the TBD is closed.
Full suite 352 tests in 64 suites green. Two findings filed.
Claude-Session: https://claude.ai/code/session_018BjQRYBR6jQja3jCRi5S3A
