The lane-resize release gets its own hold — the strip stops two-stepping through the stale snapshot

LaneWidthHold: after the release the session's frozen standard and the
WRITTEN unit count keep governing the strip until a landed snapshot
carries that width back — dividing the already-grown window by the
stale unit total in between was the visible two-step. A deliberately
separate type from CommittedHold: that hold stands in for an
arrangement and any landing retires it; this one stands in for a value
and only a landing that carries it will do. Echo reads through
LaneLayoutMath.displayUnits so the width-1 key-removal case compares
right; the watch rides landedReloads so a value-equal echo still
answers; width writes now return whether bytes reached disk so a
refused or no-op write dissolves the hold instead of arming it; the
1500ms timeout family covers the rest.

Drag-perf card 231e3693.

Claude-Session: https://claude.ai/code/session_01CqjXB7ASoWtbyoGod68k97

Kanban/UI/Board/LaneResizeHandle.swift

@@ -18,7 +18,9 @@ struct LaneResizeHandle: View {
 
     let laneID: ItemID
 
-    /// The lane's committed unit count — the k the session starts from.
+    /// The lane's committed unit count — the k the session starts from. What is **on screen**, which
+    /// while a release hold stands is the width that release wrote rather than the stale snapshot's
+    /// (`LaneResizeSession.displayUnits(of:)`).
     let committedUnits: Int
 
     /// The strip's standard (1×) width THIS render; captured as the frozen standard the instant the
@@ -60,7 +62,10 @@ struct LaneResizeHandle: View {
             .gesture(
                 DragGesture(minimumDistance: 2, coordinateSpace: .global)
                     .onChanged { value in
-                        if !session.isResizing(laneID) {
+                        // `isDragging`, not `governs`: a release hold on this very lane is still
+                        // governing the strip, and a new drag begins over it rather than being
+                        // mistaken for the old one still running (`LaneResizeSession.begin`).
+                        if !session.isDragging(laneID) {
                             // m5-drag: a resize and a card/lane move must not run at once — they
                             // would both mutate the same strip layout. The board's drag state does
                             // not exist yet; when it does, this is where the `isDragging` guard goes.
@@ -71,7 +76,7 @@ struct LaneResizeHandle: View {
                         session.update(translation: value.translation.width)
                     }
                     .onEnded { _ in
-                        guard session.isResizing(laneID) else { return }
+                        guard session.isDragging(laneID) else { return }
                         session.end { id, units in store.setLaneWidth(id, units: units) }
                         popCursor()
                     }