Keyboard ←/→ keep their place — a sticky ordinal that outlives the clamp

Lateral card navigation was pure geometry: the nearest drawn frame in the
direction. That loses the walk in the card's own title — stepping from a
10-card lane's 8th card into a 3-card lane clamps to its 3rd, and coming
back out, "the nearest frame at that height" is the 3rd card's height. The
information the user was walking at stopped being on screen, so no rule
over rectangles could have recovered it.

So it is remembered instead. `TransientBoardState.lateralOrdinal` holds the
1-based position a run of ←/→ started from, counted over the cards the board
is showing, and `NavigationMath.lateralHop` lands each hop on
`min(ordinal, target lane's count)` of the next lane that is showing cards —
collapsed and query-emptied lanes hopped over on `firstCard`'s rule rather
than by the accident of registering no frames. 8th → 3rd → 8th.

Every reset comes from one funnel and needs no enumeration anywhere: the
ordinal is a defaulted `nil` parameter on `select`, so a click, a marquee, a
↑/↓ step, an ⌥-jump, a ⌫ successor, a lane-domain arrow and the reload's
focus recovery all end the run by saying nothing. `resolve` adds the one
rule a value referencing no item can need — the ordinal never outlives the
head it was counted from — while a reload that leaves the cursor standing
leaves the run standing too.

A wide lane's interior masonry columns keep their spatial step and carry the
ordinal through untouched: a column hop is not a lane hop, and stickiness is
lane-granular over the logical order. With no lane in the direction the
geometry has the last word, which is how → still reaches the shown trash.

Claude-Session: https://claude.ai/code/session_014PtZdPwqZuqEDLc6wZMtEy

DESIGN/04-interactions.md

@@ -36,7 +36,7 @@ Selection, drag & drop, keyboard, clipboard, search. This is where the old app s
 
 ### Grammar (fixed keys — deliberately not remappable)
 
-- **Arrows**: spatial card navigation (nearest card in the direction, across interior grid columns and lanes); with a lane selected, ←/→ move lane selection; ⇧-arrow extends — except **⇧↑/⇧↓ in the lane domain, which are inert** (settled: there is nothing above the lane domain and no vertical range within it); selection scrolls into view; all grammar keys inert while a title editor is focused, and menu dispatch narrows to the text domain (focused-editor rule below).
+- **Arrows**: spatial card navigation (nearest card in the direction, across interior grid columns and lanes) — **except ←/→ crossing lanes, which preserve the origin's ordinal** (settled 2026-08-09; the *sticky ordinal*): a run of lateral presses remembers the 1-based position the card it started from held in its lane's logical order, counting the cards the board is showing (search filter respected), and each hop lands on `min(that ordinal, the target lane's count)` in the next lane that is showing cards — collapsed and query-emptied lanes hopped over as everywhere else. So a 10-3-10 walk goes 8th → 3rd (clamped) → 8th, which no rule over drawn rectangles can do: after the clamp, "8 cards down" is no longer on screen to be measured. The ordinal is **transient per-window state** (`TransientBoardState.lateralOrdinal`), never persisted, and **any non-lateral selection change resets it to the actual new position** — ↑/↓ steps, ⌥-jumps, clicks, the rubber band, ⌫'s successor, and programmatic re-selection after a reload. A wide lane's interior masonry columns keep their spatial step and do not participate: stickiness is lane-granular, and the ordinal is the lane's logical order whichever column drew the card. With a lane selected, ←/→ move lane selection; ⇧-arrow extends — except **⇧↑/⇧↓ in the lane domain, which are inert** (settled: there is nothing above the lane domain and no vertical range within it); selection scrolls into view; all grammar keys inert while a title editor is focused, and menu dispatch narrows to the text domain (focused-editor rule below).
 - **⌥-arrows jump**: ⌥↑/⌥↓ to the current lane's first/last card; ⌥←/⌥→ to the first/last lane. **The horizontal jumps land on a card** (settled — ⌥↑ is the keyboard's one entry to lane selection, so ⌥←/⌥→ never select the lane itself): the first card of the first/last *non-empty* lane, scanning inward past empty lanes; ⌥→ prefers the shown non-empty trash — its first entry — per the last-container rule (The trash below). **⌥↑ escalates into the lane domain** (settled — the keyboard's one entry to lane selection): with the lane's first card already selected, ⌥↑ selects the *lane* itself — up in the hierarchy sense, the same key one press deeper; with a lane selected, ↓ (or ⌥↓) descends back into its cards at the first (last) card, and ⌥↑ is inert. **An empty selection seeds at the first lane's first card** on any plain arrow (deterministic origin; the ⌥-jumps behave as specified regardless) — two ⌥↑ presses from nothing reach the lane domain.
 - **Return** on a selected lane: creates a card at its bottom, editor focused; Return commits and re-selects the lane (next Return = next card); ⌘↩ commits and opens the card window. Abandoned placeholders (Escape, empty commit, click-away) are discarded — creating-then-abandoning never leaves an empty card behind (untitled cards exist only when made deliberately, e.g. by an external writer or by clearing an existing title). The placeholder is store-transient overlay state — the named exception to 02-architecture.md's one-way flow; nothing exists on disk until the title commits.
 - **Inline rename tracks its target by UUID, and vanishing discards it** (the placeholder and card-window kin rules — 02-architecture.md — applied to the third inline editor): a foreign *move* mid-rename is invisible — the editor follows the UUID and the commit writes the title wherever the card now lives; a target that is trashed, deleted, or gone at commit time discards the editor and its keystrokes silently (entering the trash is a vanish from the board; nothing is ever written into a vanished folder). A write that fails *after* a valid commit is the ordinary one-shot write-failure banner. VoiceOver announces the vanished target per 10-accessibility.md's recovery rule.