The command surface was already almost entirely platform machinery —
this card proves it and pins it. Headless probes established that
NSWindow.validateMenuItem answers enablement AND rewrites the row title
from the delegate-supplied manager, so 'Undo Move 3 Cards' flows step
phrase to Edit menu with no code of ours; under the lock the rows dim
and keep their names, the correct reading of the-stack-survives. The
toolbar twins validate through validateUserInterfaceItem, which never
touches labels — 03's static-label exception proven rather than
asserted — and their specs' enablement abstention is pinned so nobody
later adds a second, disagreeing answer. The one link a headless run
cannot close is the nil-target key-window resolution itself: standard
responder-chain behavior with none of our code in it, left as the
manual check. Base-edition 'disabled without undo' scaffolding is
reworded away — every base board has undo now. New suites cover the
trash's two doors (delete-then-undo byte-identical to Put Back's
effect), position-preserving restore of a middle card, and the
capstone: five gestures forward, five presses back to the origin
board, five forward again, the menu phrase asserted after every press.
Claude-Session: https://claude.ai/code/session_01SR4XGjmBE16ZUYWpfFHXwY
Every crossing validates its expectations before writing: each step
carries per-item HistoryExpectations — folder, effective ancestor-walked
liveness, and exactly the fields the gesture set — and a mismatch pops
the step, posts the signpost ('Undo skipped — Fix login changed outside
Lanework'), and falls through to the next. Validation reads disk, not
the in-memory snapshot: the snapshot is by construction one reload
behind every app write, so a rapid second undo would false-skip against
the pre-state — disk is what current can honestly mean at press time.
Stale and failed part ways: a stale step is one the board moved past,
so dropping it loses nothing; a failed one is refused by a usually
momentary condition, so it stays put and the crossing stops with only
performWrite's own error row — which forced the provider off
NSUndoManager onto two plain arrays, since a popped group cannot be put
back. The read-only lock disables Undo/Redo through the adapter while
the stack survives to resume on clear. Delete and restore validate
presence alone — a machine timestamp is not a decision — and a
malformed field matches nothing, since it is a shape the app never
writes.
Claude-Session: https://claude.ai/code/session_01SR4XGjmBE16ZUYWpfFHXwY
The store is the Writer boundary, so it computes and registers
inverses: a weak history sink bound at session composition, one
HistoryStep per gesture at exactly the brackets that were already one
performWrite each — multi-card moves, style batches, width pairs, and
multi-row restores each undo as one plurally-titled step, and the Edit
session registers once at the flip from the bytes disk held before its
first landed write, debounce ticks registering nothing. Crossings run
through performWrite, so an undo brackets the watcher, echoes through
the reload, and reaches every window; every closure captures values,
never snapshots. The inventory follows 13 exactly: moves return to
origin lane and order, renames restore or remove the title key,
restyles and resizes restore field values or absence, tombstones and
restores swap with captured timestamps, and an undone create is a real
removal — no trace — with redo re-materializing the same UUID from
bytes captured at gesture time. Purge, attachments, repair,
bookkeeping, checkbox flips, raw Apply, and the whole arrival family
register nothing, each exclusion documented where it lives. Step names
speak 06's verb vocabulary through the new HistoryPhrase.
Claude-Session: https://claude.ai/code/session_01SR4XGjmBE16ZUYWpfFHXwY
rzen