The lane plate's strays return to their anchors — the replica's wash leaves the height arithmetic it broke

The pathfinder surface stack landed in e1ffe71 entangled with staged-index
placement drift: the replica's wash block sat inside replicaHeight (a CGFloat
has no .background — HEAD did not build), the body plate rode outside the cut
dim, the lanePlate property and the DESIGN bullet sat away from their kin.
Pure relocation, no new lines: every block moves to the anchor it was written
for. Verified by an isolated build of this tree.

Claude-Session: https://claude.ai/code/session_01SR4XGjmBE16ZUYWpfFHXwY

DESIGN/03-board-ui.md

@@ -33,8 +33,8 @@ Toolbars are **pure enhancement**: every function they host already has a menu i
 ### Capabilities (settled)
 
 - **`background`** on board / lane / card: palette name (kebab-case, hand-editable) or `#RRGGBB[AA]` hex. Board color paints the board window's content background (the surface behind and between lanes). Lane and card color are **edge accents, not fills** (settled in the pathfinder's treatment shootout — its settings matrix of C-series lane / K-series card variants landed on **C7 · full-column top edge** and **K1 · left edge stripe**): a lane's color paints a full-width band along its top edge, a card's a stripe along its left edge; the surfaces themselves keep the standard chrome, so colored title text never sits on a colored fill.
-- **`icon`**: SF Symbol per item with per-level defaults (board `rectangle.split.3x1`, lane `square.stack`, card `doc.text`).
 - **The standard chrome is the pathfinder's surface stack** (settled 2026-08-06): the window keeps the neutral system background; every lane wears a quiet quaternary-wash plate (the trash plate's own figure — translucent, so a board-chosen color shows through and the board-level ink rule keeps its premise; opaque under Reduce Transparency, the trash precedent); every card sits on an opaque `controlBackgroundColor` plate — white over the washed lane in light appearance, a step *darker* than the window in dark. One plate value for every face a card draws (resting, replicas, placeholder, arriving), so a card is the same object wherever it renders.
+- **`icon`**: SF Symbol per item with per-level defaults (board `rectangle.split.3x1`, lane `square.stack`, card `doc.text`).
 - **`iconColor`**: resolved — **schema yes, control no**. The field renders when hand-written (tint palette name or hex); the app offers no control for it (Controls below).
 - The pathfinder's palettes (12 icon tints, 12 backgrounds) carry over as the starting point. **The 12+12 split is a picker split, not a name split** (settled): color resolution searches foregrounds then backgrounds, so a hand-written `background: carnation` (an icon-tint name) resolves and paints — the split governs what the grids offer, never what a name means.
 

Kanban/UI/Board/LaneView.swift

@@ -166,15 +166,15 @@ struct LaneView: View, Equatable {
             .padding(BoardMetrics.lanePlatePadding(bodyPointSize: pointSize))
         }
         .background(selectionBackground)
+        // Behind the selection wash, not composed into it: the plate is the lane's resting
+        // surface, the wash above it is the selection's own layer, and stacked `.background`s
+        // put the later one further back.
+        .background(lanePlate)
         .overlay(selectionStroke)
         // The deferred cut's dim (04-interactions.md ▸ Clipboard) — on the whole lane, because a cut
         // lane is cut cards and all.
         .cutTreatment(of: lane.id, in: store)
         .onGeometryChange(for: CGFloat.self) { $0.size.height } action: { measuredHeight = $0 }
-        // Behind the selection wash, not composed into it: the plate is the lane's resting
-        // surface, the wash above it is the selection's own layer, and stacked `.background`s
-        // put the later one further back.
-        .background(lanePlate)
         // **This lane's drop target**, on the whole body. It accepts *every* session type and routes
         // internally — card sessions against this lane's masonry zones, lane sessions forwarded to
         // the strip's logic, external Finder file sessions against those same zones — because
@@ -657,6 +657,10 @@ struct LaneView: View, Equatable {
             .padding(BoardMetrics.lanePlatePadding(bodyPointSize: pointSize))
         }
         .frame(width: replicaWidth, height: replicaHeight, alignment: .topLeading)
+        // The lane's own wash over an opaque base — the replica floats over whatever the cursor is
+        // above, so unlike the resting lane it cannot let the wash composite against the board; the
+        // opaque `.background` behind it stands in for the window's neutral surface.
+        .background(lanePlate)
         .background(RoundedRectangle(cornerRadius: cornerRadius).fill(.background))
         .clipShape(RoundedRectangle(cornerRadius: cornerRadius))
         .dragReplicaShadow()
@@ -672,10 +676,6 @@ struct LaneView: View, Equatable {
 
     private var replicaHeight: CGFloat {
         max(measuredHeight, BoardMetrics.laneReplicaMinimumHeight(bodyPointSize: pointSize))
-        // The lane's own wash over an opaque base — the replica floats over whatever the cursor is
-        // above, so unlike the resting lane it cannot let the wash composite against the board; the
-        // opaque `.background` behind it stands in for the window's neutral surface.
-        .background(lanePlate)
     }
 
     /// Where the title bar sits inside the replica — its **centre**, measured down from the replica's
@@ -978,6 +978,16 @@ struct LaneView: View, Equatable {
         store.selection.container == .board && store.selection.ids.contains(lane.id)
     }
 
+    /// The lane's resting plate — the standard chrome's middle step (03-board-ui.md § Styling ▸
+    /// Capabilities: window, washed lane, opaque card), the same quaternary wash the trash column
+    /// wears (`Accommodations.lanePlateWash`). Translucent deliberately: a board-chosen colour
+    /// shows through, so the header ink computed against the board's background (`headerInk`)
+    /// keeps its premise on a painted board.
+    private var lanePlate: some View {
+        RoundedRectangle(cornerRadius: cornerRadius)
+            .fill(Accommodations.lanePlateWash(reduceTransparency: reduceTransparency).style)
+    }
+
     /// The selection treatment: a subtle whole-lane accent wash and stroke. Deliberately quiet —
     /// 03-board-ui.md gives lane *colour* to the top-edge accent band, so selection must not read as
     /// a fill that would compete with it once that lands.
@@ -997,16 +1007,6 @@ struct LaneView: View, Equatable {
             .strokeBorder(plateStroke, lineWidth: plateStrokeWidth)
     }
 
-    /// The lane's resting plate — the standard chrome's middle step (03-board-ui.md § Styling ▸
-    /// Capabilities: window, washed lane, opaque card), the same quaternary wash the trash column
-    /// wears (`Accommodations.lanePlateWash`). Translucent deliberately: a board-chosen colour
-    /// shows through, so the header ink computed against the board's background (`headerInk`)
-    /// keeps its premise on a painted board.
-    private var lanePlate: some View {
-        RoundedRectangle(cornerRadius: cornerRadius)
-            .fill(Accommodations.lanePlateWash(reduceTransparency: reduceTransparency).style)
-    }
-
     private var plateStroke: AnyShapeStyle {
         if isSelected {
             AnyShapeStyle(Color.accentColor)