feat(editor): door/window placement-feel polish + placement-state refactor (#411)

Round 8 of the opening-placement UX work. Make door/window placement feel
physical and predictable, and unify the validity/placement logic behind one
shared decision.

UX:
- Window default sill 0.5 m (DEFAULT_WINDOW_SILL_M) so fresh windows float
  slightly above the floor; existing windows keep their own sill.
- Dev-only floor "shadow" projection for windows during placement/move
  (footprint + dashed drop-line) so an elevated window's plan spot is legible.
- Move SFX: one soft grid-snap click per grid step — identical free-following
  over floor or sliding on a wall (keyed on the raw cursor; per-frame + step
  dedup), no separate snap cue (that was a "double"). Mirrored into the 2D
  floorplan-move so 2D and 3D match.
- Shift = force-place over a collision (commit allowed; ghost stays a red
  warning) + free-place (lands at the raw cursor but keeps the alignment guides
  visible). Tint flips green/red live when Shift is pressed/released stationary.
- On-wall preview is now the tinted ghost (green placeable / red colliding),
  matching the free-follow ghost, instead of a pale solid mesh + thin wireframe.
- R-flip fixes: always toggles (no initial no-op needing a second press),
  e.repeat filtered, ghost rebuilds with the live `side`, and the ghost's
  on-wall world yaw uses `itemRotation - wallAngle` so it faces exactly what
  commit places (cursorRotation was π off for the asymmetric ghost). R ownership
  follows the current pointer pane (capture-phase + stopImmediatePropagation in
  the 2D overlay) so 3D and 2D never double-flip or go dead.

Refactor / quality:
- New `resolveOpeningPlacement({collides,forcePlace}) -> {placeable,tint}` in
  shared/wall-attach-target.ts — the single source of truth the ghost tint AND
  the commit gates both consume, so they can't disagree under Shift.
- Consolidated the byte-identical `hasWallChildOverlap` into one shared impl
  (door-math/window-math re-export it).
- applyGhost gained a green "valid" tint.
- Removed dead `cursorRotation` from the move-tool targets after the yaw fix.

Docs: "2D <-> 3D behavioral parity" principle in wiki/architecture/tools.md
(+ README + AGENTS.md) — applicable behaviors must exist in both views.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

AGENTS.md

@@ -34,6 +34,7 @@ Read the relevant page in `wiki/architecture/` **before** writing code. The page
 
 - Adding a node type → `node-schemas.md`, `renderers.md`, `systems.md`
 - Adding a tool → `tools.md`, `spatial-queries.md`, `events.md`
+- Adding / changing a placement or move interaction → `tools.md` ("2D ↔ 3D behavioral parity": applicable behaviors must exist in both views; port the change to the sibling 2D/3D file in the same PR)
 - Adding a system → `systems.md`, `scene-registry.md`
 - Anything in `packages/viewer` → `viewer-isolation.md`, `layers.md`
 - Anything touching selection → `selection-managers.md`, `scene-registry.md`, `events.md`

packages/editor/src/components/editor-2d/floorplan-registry-move-overlay.tsx

@@ -124,6 +124,14 @@ export function FloorplanRegistryMoveOverlay() {
       // to be consumed. That legacy flow is gone in the registry layer;
       // all entries use the action menu now.
       let hasMovedSinceStart = false
+      // Live cursor location — updated on EVERY pointermove (even over the 3D
+      // canvas) so R-key ownership can follow the pointer's CURRENT pane rather
+      // than the sticky `hasMovedSinceStart`. Without this, once the user touched
+      // the 2D pane the overlay claimed R forever and the 3D flip went dead.
+      let pointerOverFloorplan = false
+      const onPointerTrack = (event: PointerEvent) => {
+        pointerOverFloorplan = isPointerOverFloorplanScene(event.clientX, event.clientY)
+      }
 
       const onMove = (event: PointerEvent) => {
         // Skip 3D-canvas / other-UI cursor moves so the overlay only
@@ -288,18 +296,24 @@ export function FloorplanRegistryMoveOverlay() {
         // apply so the 2D symbol updates immediately; kinds without a facing
         // leave `flipSide` unset and R falls through to the global handler.
         //
-        // Only when THIS overlay is the active mover — i.e. the user has moved
-        // the pointer over the 2D pane (`hasMovedSinceStart`). The 3D move tool
-        // also listens for R while a door/window `movingNode` is placed (split
-        // / 3D-only view); gating on `hasMovedSinceStart` keeps the two from
-        // both flipping (or double-playing the cue) on a single R press.
+        // Ownership follows the CURRENT pointer pane, not a sticky flag: the 3D
+        // move tool ALSO listens for R on `window`. We own R only while the
+        // cursor is over the 2D floor-plan pane (`pointerOverFloorplan`) AND the
+        // 2D mover has actually engaged (`hasMovedSinceStart`); then we
+        // `stopImmediatePropagation` (this handler is CAPTURE-phase, so it runs
+        // first) so the 3D tool can't also flip. When the cursor is over the 3D
+        // pane we yield — the 3D tool owns R there. (The old sticky
+        // `hasMovedSinceStart`-only gate made the overlay claim R forever after
+        // the first 2D move, killing the 3D flip.)
         if (event.key === 'r' || event.key === 'R') {
-          if (!(session.flipSide && hasMovedSinceStart)) return
+          if (!(session.flipSide && hasMovedSinceStart && pointerOverFloorplan)) return
+          if (event.repeat) return
           const t = event.target as HTMLElement | null
           if (t && (t.tagName === 'INPUT' || t.tagName === 'TEXTAREA' || t.isContentEditable)) {
             return
           }
           event.preventDefault()
+          event.stopImmediatePropagation()
           session.flipSide()
           sfxEmitter.emit('sfx:item-rotate')
           return
@@ -349,13 +363,18 @@ export function FloorplanRegistryMoveOverlay() {
         setMovingNode(null)
       }
 
+      window.addEventListener('pointermove', onPointerTrack)
       window.addEventListener('pointermove', onMove)
       window.addEventListener('pointerup', onPointerUp)
-      window.addEventListener('keydown', onKey)
+      // Capture phase so this runs BEFORE the 3D move tool's bubble-phase R
+      // listener — when the cursor is over the 2D pane, `stopImmediatePropagation`
+      // then pre-empts it so only one handler flips.
+      window.addEventListener('keydown', onKey, true)
       return () => {
+        window.removeEventListener('pointermove', onPointerTrack)
         window.removeEventListener('pointermove', onMove)
         window.removeEventListener('pointerup', onPointerUp)
-        window.removeEventListener('keydown', onKey)
+        window.removeEventListener('keydown', onKey, true)
         // Unmount cleanup. `historyPaused === true` here means none of
         // our terminal paths (commit, Esc) ran in this overlay — they
         // each call `resumeSceneHistory` and flip the flag.

packages/nodes/src/door/door-math.ts

@@ -1,12 +1,4 @@
-import {
-  type AnyNodeId,
-  type DoorNode,
-  getScaledDimensions,
-  type ItemNode,
-  useScene,
-  type WallNode,
-  type WindowNode,
-} from '@pascal-app/core'
+import type { WallNode } from '@pascal-app/core'
 
 /**
  * Keep the door handle at the same relative height when the door is resized:
@@ -64,63 +56,7 @@ export function clampToWall(
   return { clampedX, clampedY }
 }
 
-/**
- * Checks if a proposed door position overlaps any existing wall children.
- * Handles item, window, and door types.
- */
-export function hasWallChildOverlap(
-  wallId: string,
-  clampedX: number,
-  clampedY: number,
-  width: number,
-  height: number,
-  ignoreId?: string,
-): boolean {
-  const nodes = useScene.getState().nodes
-  const wallNode = nodes[wallId as AnyNodeId] as WallNode | undefined
-  if (!wallNode) return true
-  const halfW = width / 2
-  const halfH = height / 2
-  const newBottom = clampedY - halfH
-  const newTop = clampedY + halfH
-  const newLeft = clampedX - halfW
-  const newRight = clampedX + halfW
-
-  for (const childId of Array.isArray(wallNode.children) ? wallNode.children : []) {
-    if (childId === ignoreId) continue
-    const child = nodes[childId as AnyNodeId]
-    if (!child) continue
-
-    let childLeft: number, childRight: number, childBottom: number, childTop: number
-
-    if (child.type === 'item') {
-      const item = child as ItemNode
-      if (item.asset.attachTo !== 'wall' && item.asset.attachTo !== 'wall-side') continue
-      const [w, h] = getScaledDimensions(item)
-      childLeft = item.position[0] - w / 2
-      childRight = item.position[0] + w / 2
-      childBottom = item.position[1]
-      childTop = item.position[1] + h
-    } else if (child.type === 'window') {
-      const win = child as WindowNode
-      childLeft = win.position[0] - win.width / 2
-      childRight = win.position[0] + win.width / 2
-      childBottom = win.position[1] - win.height / 2
-      childTop = win.position[1] + win.height / 2
-    } else if (child.type === 'door') {
-      const door = child as DoorNode
-      childLeft = door.position[0] - door.width / 2
-      childRight = door.position[0] + door.width / 2
-      childBottom = door.position[1] - door.height / 2
-      childTop = door.position[1] + door.height / 2
-    } else {
-      continue
-    }
-
-    const xOverlap = newLeft < childRight && newRight > childLeft
-    const yOverlap = newBottom < childTop && newTop > childBottom
-    if (xOverlap && yOverlap) return true
-  }
-
-  return false
-}
+// Wall-child overlap is shared by door + window placement (one source of
+// truth in `shared/wall-attach-target.ts`). Re-exported here so existing
+// `./door-math` importers don't change.
+export { hasWallChildOverlap } from '../shared/wall-attach-target'

packages/nodes/src/door/floorplan-move.ts

@@ -8,12 +8,13 @@ import {
   type WallNode,
   WallNode as WallNodeSchema,
 } from '@pascal-app/core'
-import { snapToHalf, usePlacementPreview } from '@pascal-app/editor'
+import { snapToHalf, triggerSFX, usePlacementPreview } from '@pascal-app/editor'
 import { createFloorplanCursorResolver } from '../shared/floorplan-cursor'
 import { getOpeningHostLevelId, getRoofHostedOpeningPlanPoint } from '../shared/roof-opening-host'
 import {
   findClosestWallInPlan,
   projectWallLocalPointToPlan,
+  resolveOpeningPlacement,
   snapLocalXToNeighbors,
 } from '../shared/wall-attach-target'
 import { clampToWall, hasWallChildOverlap } from './door-math'
@@ -87,6 +88,25 @@ export const doorFloorplanMoveTarget: FloorplanMoveTarget<DoorNode> = ({ node })
   // the cursor as a ghost (like the 3D move) and is NOT committable — a door
   // needs a wall. Starts true so a click before any move keeps the door put.
   let onWall = true
+  // Shift force-place (last apply's modifier) — lets `canCommit` allow an
+  // overlapping placement, matching the 3D move. Read in `canCommit` so a Shift-
+  // held commit over a collision lands instead of reverting.
+  let forcePlace = false
+
+  // Move SFX — parity with the 3D `MoveDoorTool`: ONE soft `sfx:grid-snap` click
+  // per grid step, identical free-following or sliding on a wall, keyed on the
+  // RAW cursor (not the snapped along-wall value). No separate floor→wall cue —
+  // that distinct sound was the "double" the user heard. 2D `apply` runs once per
+  // pointermove, so the step-key dedup is sufficient (no per-frame guard needed).
+  const STEP_M = 0.1
+  let lastStepKey: string | null = null
+  const tickGridStep = (...coords: number[]) => {
+    const key = coords.map((c) => Math.round(c / STEP_M)).join(',')
+    if (key !== lastStepKey) {
+      lastStepKey = key
+      triggerSFX('sfx:grid-snap')
+    }
+  }
 
   // Off-wall: float the faithful door symbol at the cursor (via a synthetic
   // wall fed to the placement-preview layer) and hide the real node, so the
@@ -104,14 +124,23 @@ export const doorFloorplanMoveTarget: FloorplanMoveTarget<DoorNode> = ({ node })
       end: [planPoint[0] + half, planPoint[1]],
       thickness: 0.1,
     })
+    // Reflect the R-flip on the floating ghost so its swing-arc faces the side
+    // that will be committed (the synthetic wall is plan-X aligned, so a back
+    // facing is a π yaw; the symbol builder also reads `side`).
+    const ghostSide: DoorNode['side'] = flipped
+      ? node.side === 'front'
+        ? 'back'
+        : 'front'
+      : node.side
     const ghost = {
       ...node,
+      side: ghostSide,
       parentId: wall.id,
       wallId: wall.id,
       roofSegmentId: undefined,
       roofFace: undefined,
       position: [half, node.position[1], 0] as [number, number, number],
-      rotation: [0, 0, 0] as [number, number, number],
+      rotation: [0, flipped ? Math.PI : 0, 0] as [number, number, number],
       visible: true,
     } as DoorNode
     usePlacementPreview.getState().set(ghost, wall)
@@ -125,6 +154,7 @@ export const doorFloorplanMoveTarget: FloorplanMoveTarget<DoorNode> = ({ node })
     },
     apply({ planPoint, modifiers }) {
       lastApply = { planPoint, modifiers }
+      forcePlace = modifiers.shiftKey === true
       // Drop any stale live transform left by the 3D `MoveDoorTool` (it
       // publishes one on every wall hover). The 2D registry layer renders
       // door/window from `useLiveTransforms` IN PREFERENCE to the scene node,
@@ -140,7 +170,9 @@ export const doorFloorplanMoveTarget: FloorplanMoveTarget<DoorNode> = ({ node })
       const resolvedPlanPoint = resolveCursor(planPoint)
       const hit = findClosestWallInPlan(resolvedPlanPoint, nodes, startLevelId)
       if (!hit) {
-        // Off any wall — free-follow the cursor (not committable).
+        // Off any wall — free-follow the cursor (not committable). Click per grid
+        // cell as the ghost slides over open floor.
+        tickGridStep(resolvedPlanPoint[0], resolvedPlanPoint[1])
         freeFollow(resolvedPlanPoint)
         return
       }
@@ -168,6 +200,11 @@ export const doorFloorplanMoveTarget: FloorplanMoveTarget<DoorNode> = ({ node })
       const snappedLocalX = neighborX ?? (modifiers.shiftKey ? hit.localX : snapToHalf(hit.localX))
       const { clampedX, clampedY } = clampToWall(hit.wall, snappedLocalX, node.width, node.height)
 
+      // One click per grid step, keyed on the RAW along-wall cursor (`hit.localX`,
+      // not the snapped value) so the wall slide ticks at the same cadence as the
+      // off-wall ghost — the same SFX, no separate snap cue.
+      tickGridStep(hit.localX)
+
       // Apply the R-flip on top of the wall-derived side.
       const side: DoorNode['side'] = flipped ? (hit.side === 'front' ? 'back' : 'front') : hit.side
       const itemRotation = hit.itemRotation + (flipped ? Math.PI : 0)
@@ -204,9 +241,10 @@ export const doorFloorplanMoveTarget: FloorplanMoveTarget<DoorNode> = ({ node })
       if (!onWall) return false
       const live = useScene.getState().nodes[node.id as AnyNodeId] as DoorNode | undefined
       if (!live || live.type !== 'door') return false
-      // Block commit if the door overlaps any other wall child at its
-      // current position. The 3D port has the same guard.
-      const overlapping = hasWallChildOverlap(
+      // Block commit if the door overlaps another wall child — UNLESS Shift
+      // force-places (same `placeable` rule as the 3D move + the shared
+      // `resolveOpeningPlacement`).
+      const collides = hasWallChildOverlap(
         live.parentId as string,
         live.position[0],
         live.position[1],
@@ -214,7 +252,7 @@ export const doorFloorplanMoveTarget: FloorplanMoveTarget<DoorNode> = ({ node })
         live.height,
         live.id,
       )
-      return !overlapping
+      return resolveOpeningPlacement({ collides, forcePlace }).placeable
     },
     commit() {
       // Own the atomic write so the overlay takes the deterministic

packages/nodes/src/door/move-tool.tsx

@@ -14,7 +14,6 @@ import {
   type WallEvent,
 } from '@pascal-app/core'
 import {
-  calculateCursorRotation,
   calculateItemRotation,
   consumePlacementDragRelease,
   EDITOR_LAYER,
@@ -26,7 +25,7 @@ import {
   useEditor,
 } from '@pascal-app/editor'
 import { useViewer } from '@pascal-app/viewer'
-import { useCallback, useEffect, useMemo, useRef } from 'react'
+import { useCallback, useEffect, useMemo, useRef, useState } from 'react'
 import { BoxGeometry, EdgesGeometry, type Group } from 'three'
 import { LineBasicNodeMaterial } from 'three/webgpu'
 import {
@@ -38,8 +37,10 @@ import {
   type RoofWallOpeningTarget,
   resolveRoofWallOpeningTarget,
 } from '../shared/roof-wall-opening-placement'
+import { resolveOpeningPlacement } from '../shared/wall-attach-target'
 import { resolveWallSlideAlignment } from '../shared/wall-opening-alignment'
 import { clampToWall, hasWallChildOverlap, wallLocalToWorld } from './door-math'
+import DoorPreview from './preview'
 
 const edgeMaterial = new LineBasicNodeMaterial({
   color: 0xef_44_44,
@@ -51,6 +52,40 @@ const edgeMaterial = new LineBasicNodeMaterial({
 const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) => {
   const cursorGroupRef = useRef<Group>(null!)
 
+  // The door preview ghost. Shown for the WHOLE move so the user always sees a
+  // translucent door tinted by placement state — red off-wall or colliding,
+  // green on a valid wall — exactly like the free-follow ghost. The real node
+  // stays hidden until commit (the wall still cuts its hole from the node data,
+  // so the opening reads correctly behind the ghost). `null` = not previewing
+  // (committed / torn down). See the matching `DoorPreview` tint.
+  const [ghostPose, setGhostPose] = useState<{
+    position: [number, number, number]
+    rotationY: number
+    tint: 'valid' | 'invalid'
+    // The door's facing side at the cursor. R-flip changes it mid-placement and
+    // the door geometry's swing/hinge depends on it, so the ghost must rebuild
+    // with the LIVE side — otherwise the preview shows the pre-flip orientation
+    // while commit places the flipped one.
+    side: DoorNode['side']
+  } | null>(null)
+
+  // Ghost preview node: the moving door with a zeroed transform + the live
+  // facing side. `updateDoorMesh` bakes `position`/`rotation` into the mesh (the
+  // `<group>` wrapper already places it, so we zero those to avoid a double
+  // offset) and reads `side` for the swing/hinge direction — so the ghost
+  // matches exactly what commit will place, including an R-flip. Falls back to
+  // the moving node's own side when no pose is active.
+  const ghostSide = ghostPose?.side ?? movingDoorNode.side
+  const ghostNode = useMemo(
+    () => ({
+      ...movingDoorNode,
+      side: ghostSide,
+      position: [0, 0, 0] as [number, number, number],
+      rotation: [0, 0, 0] as [number, number, number],
+    }),
+    [movingDoorNode, ghostSide],
+  )
+
   const exitMoveMode = useCallback(() => {
     useEditor.getState().setMovingNode(null)
   }, [])
@@ -76,6 +111,10 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
       roofSegmentId: movingDoorNode.roofSegmentId,
       roofFace: movingDoorNode.roofFace,
       metadata: movingDoorNode.metadata,
+      // Free-follow hides the node (visible:false); every revert path must
+      // restore the original visibility or an existing door cancelled over open
+      // floor would stay invisible.
+      visible: movingDoorNode.visible,
     }
 
     if (!isNew) {
@@ -95,6 +134,35 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
     // pointermove (shared DOM timeStamp) — that's the only thing that snaps.
     let freeFollowing = false
     let lastMeshEventTime = -1
+    // Last open-floor cursor point (level-local X/Z), so an R-flip or Shift change
+    // while free-following can re-run the ghost at the same spot with the new
+    // facing/tint — no pointer move required.
+    let lastFloorPoint: [number, number] | null = null
+    // Live Shift state (force-place). Tracked here so the preview tint can be
+    // re-evaluated when Shift is pressed/released with the pointer stationary —
+    // the stored WallEvent carries a STALE shiftKey from the last move.
+    let shiftHeld = false
+    // Movement SFX: ONE soft `sfx:grid-snap` click each time the door crosses a
+    // grid step — identical whether free-following over open floor or sliding
+    // along a wall, so the two feel the same (the user's ask). Always keyed on
+    // the RAW cursor position (continuous ~0.1m cadence), never the snapped
+    // along-wall value, so the wall slide ticks at the same rate as the ghost.
+    // Two guards prevent a doubled/flammed cue: `lastStepKey` (emit only when
+    // the quantized cell changes) AND `lastTickFrame` (at most one tick per DOM
+    // pointermove — a wall mesh can emit `wall:move` more than once per move, and
+    // the grid + wall paths can both run). No separate snap cue: a distinct
+    // floor→wall sound was the "double" the user heard.
+    const STEP_M = 0.1
+    let lastStepKey: string | null = null
+    let lastTickFrame = -1
+    const tickGridStep = (frame: number, ...coords: number[]) => {
+      if (frame === lastTickFrame) return
+      const key = coords.map((c) => Math.round(c / STEP_M)).join(',')
+      if (key === lastStepKey) return
+      lastStepKey = key
+      lastTickFrame = frame
+      triggerSFX('sfx:grid-snap')
+    }
     // The door's chosen facing side. R flips it mid-placement (front ↔ back,
     // same as the committed-selected R flip) so the user can reorient before
     // committing. Initialised from the moving node's side.
@@ -104,7 +172,6 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
       wallId: string
       side: DoorNode['side']
       itemRotation: number
-      cursorRotation: number
       clampedX: number
       clampedY: number
       valid: boolean
@@ -143,6 +210,7 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
       if (cursorGroupRef.current) cursorGroupRef.current.visible = false
       useAlignmentGuides.getState().clear()
       clearOpeningGuides3D()
+      setGhostPose(null)
     }
 
     // Alignment candidates — anchors of every OTHER alignable object (the
@@ -172,8 +240,6 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
       return {
         side,
         itemRotation: calculateItemRotation(event.normal) + rotationOffset,
-        cursorRotation:
-          calculateCursorRotation(event.normal, event.node.start, event.node.end) + rotationOffset,
       }
     }
 
@@ -185,7 +251,7 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
       }
       if (event.node.parentId !== getLevelId()) return
 
-      const { side, itemRotation, cursorRotation } = getPlacementOrientation(event)
+      const { side, itemRotation } = getPlacementOrientation(event)
 
       const rawLocalX = event.localPosition[0]
       if (!dragAnchor || dragAnchor.wallId !== event.node.id) {
@@ -201,8 +267,10 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
         rawLocalX: targetLocalX,
         width: movingDoorNode.width,
         candidates: alignmentCandidates,
-        bypass: event.nativeEvent?.altKey === true || event.nativeEvent?.shiftKey === true,
-        bypassSnap: event.nativeEvent?.shiftKey === true,
+        // Alt still hard-disables alignment (no guides). Shift = free-place:
+        // land at the raw cursor but keep showing the alignment guides.
+        bypass: event.nativeEvent?.altKey === true,
+        freePlace: event.nativeEvent?.shiftKey === true,
       })
       const { clampedX, clampedY } = clampToWall(
         event.node,
@@ -225,7 +293,6 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
         wallId: event.node.id,
         side,
         itemRotation,
-        cursorRotation,
         clampedX,
         clampedY,
         valid,
@@ -234,6 +301,16 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
     }
 
     const applyPreview = (target: NonNullable<typeof lastTarget>) => {
+      // Same click as the off-wall ghost: one grid-snap tick per grid step,
+      // keyed on the RAW cursor along-wall position (not the snapped clampedX,
+      // whose ~0.5m jumps would tick at a different cadence). Per-frame guard
+      // collapses any duplicate wall events on the same pointermove.
+      tickGridStep(target.event.nativeEvent?.timeStamp ?? -1, target.event.localPosition[0])
+      // Keep the REAL node hidden and show a tinted ghost in the wall opening —
+      // green when placeable, red when it collides — the same translucent ghost
+      // the free-follow uses, so validity reads at a glance. The node position is
+      // still written (so the wall cuts the hole at the right spot) but
+      // `visible:false` keeps the pale solid mesh from competing with the ghost.
       if (currentHostId !== target.wallId) {
         useScene.getState().updateNode(movingDoorNode.id, {
           position: [target.clampedX, target.clampedY, 0],
@@ -243,6 +320,7 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
           wallId: target.wallId,
           roofSegmentId: undefined,
           roofFace: undefined,
+          visible: false,
         })
         markHostDirty(currentHostId)
         currentHostId = target.wallId
@@ -260,17 +338,37 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
       })
       markHostDirtyThrottled(target.wallId)
 
-      updateCursor(
-        wallLocalToWorld(
+      // Position the tinted ghost at the wall opening (world frame), facing the
+      // wall normal + the live side (so an R-flip shows correctly). The
+      // wireframe cursor is no longer used on a wall. Tint comes from the SHARED
+      // placement decision — green when placeable (incl. Shift force-place over a
+      // collision), red otherwise — the SAME `placeable` the commit gate uses.
+      if (cursorGroupRef.current) cursorGroupRef.current.visible = false
+      const placement = resolveOpeningPlacement({
+        collides: !target.valid,
+        forcePlace: shiftHeld,
+      })
+      // The committed door is a CHILD of the wall mesh (group yaw = -wallAngle)
+      // with wall-local `itemRotation` (0 front / π back). The ghost is a
+      // scene-root world-space group, so its world yaw must be
+      // `-wallAngle + itemRotation` to face the same way as commit.
+      // `cursorRotation` (the old symmetric-wireframe yaw) is π off here.
+      const wallAngle = Math.atan2(
+        target.wallNode.end[1] - target.wallNode.start[1],
+        target.wallNode.end[0] - target.wallNode.start[0],
+      )
+      setGhostPose({
+        position: wallLocalToWorld(
           target.wallNode,
           target.clampedX,
           target.clampedY,
           getLevelYOffset(),
           getSlabElevation(target.event),
         ),
-        target.cursorRotation,
-        target.valid,
-      )
+        rotationY: target.itemRotation - wallAngle,
+        tint: placement.tint,
+        side: target.side,
+      })
 
       publishOpeningGuidesForWallEvent({
         wall: target.wallNode,
@@ -351,6 +449,9 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
           parentId: target.wallId,
           roofSegmentId: undefined,
           roofFace: undefined,
+          // The moving node is hidden during free-follow; the committed door
+          // must be visible regardless of the pre-commit free-follow state.
+          visible: true,
         })
         useScene.getState().createNode(node, target.wallId as AnyNodeId)
         placedId = node.id
@@ -364,6 +465,7 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
           roofSegmentId: original.roofSegmentId,
           roofFace: original.roofFace,
           metadata: original.metadata,
+          visible: original.visible,
         })
         useScene.temporal.getState().resume()
 
@@ -375,6 +477,7 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
           wallId: target.wallId,
           roofSegmentId: undefined,
           metadata: {},
+          visible: true,
         })
 
         if (original.parentId && original.parentId !== target.wallId) {
@@ -400,7 +503,11 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
       if (event.node.parentId !== getLevelId()) return
 
       const target = lastTarget?.wallId === event.node.id ? lastTarget : resolveMoveTarget(event)
-      if (!target?.valid) return
+      // Shift force-places: commit even when the door overlaps another opening.
+      // The preview keeps its red invalid tint as a warning; Shift just lifts the
+      // commit block. Read shift from THIS event so it's never stale at commit.
+      if (!target) return
+      if (!target.valid && event.nativeEvent?.shiftKey !== true) return
       commitToWall(target)
       event.stopPropagation()
     }
@@ -420,13 +527,29 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
       lastRoofEvent = null
     }
 
-    // Free-follow: the door rides the cursor over empty floor, parented to the
-    // level like an item node (lifted so it stands on the floor). No wall to
-    // attach to, so it is not committable here.
-    const freeFollowAt = (localX: number, localZ: number) => {
+    // Reveal the real door node + drop the ghost. Used by the roof-face path,
+    // which previews with the real mesh (the ghost-tint flow is wall-specific).
+    const revealRealNode = () => {
+      setGhostPose(null)
+      const live = useScene.getState().nodes[movingDoorNode.id as AnyNodeId] as DoorNode | undefined
+      if (live && live.visible === false) {
+        useScene.getState().updateNode(movingDoorNode.id, { visible: true })
+      }
+    }
+
+    // Free-follow: over open floor there's no wall to host the door, so instead
+    // of dragging the real (pale, near-invisible-on-grid) node around we hide it
+    // and float a red translucent ghost at the cursor — same treatment the raw
+    // `DoorTool` build path uses. The node still re-parents to the level so a
+    // later wall-snap / commit has a clean base, but stays `visible:false` until
+    // a wall is hovered.
+    const freeFollowAt = (localX: number, localZ: number, frame: number) => {
       freeFollowing = true
       lastTarget = null
       lastRoofEvent = null
+      // Click per grid cell as the ghost slides over open floor (X+Z) — the
+      // same `tickGridStep` the on-wall slide uses, so both feel identical.
+      tickGridStep(frame, localX, localZ)
       hideCursor()
       useLiveTransforms.getState().clear(movingDoorNode.id)
       const levelId = getLevelId()
@@ -445,6 +568,7 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
           wallId: undefined,
           roofSegmentId: undefined,
           roofFace: undefined,
+          visible: false,
         })
         currentHostId = levelId
       } else {
@@ -452,8 +576,18 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
           position: [localX, y, localZ],
           rotation: [0, yaw, 0],
           side: sideOverride,
+          visible: false,
         })
       }
+      // Float the red (invalid — no wall) ghost at the cursor, level-Y lifted so
+      // it stands on the floor, matching the door's chosen facing (sideOverride
+      // carries the R-flip so the ghost swing direction matches commit).
+      setGhostPose({
+        position: [localX, getLevelYOffset() + y, localZ],
+        rotationY: yaw,
+        tint: 'invalid',
+        side: sideOverride,
+      })
     }
 
     const onGridMove = (event: GridEvent) => {
@@ -468,7 +602,8 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
       // so snapping engages only when the cursor ray actually hovers a wall
       // (`onWallMove`). Over open floor the door just follows the cursor.
       const [x, , z] = event.localPosition
-      freeFollowAt(x, z)
+      lastFloorPoint = [x, z]
+      freeFollowAt(x, z, event.nativeEvent?.timeStamp ?? -1)
     }
 
     // ── Roof-segment wall faces ─────────────────────────────────────
@@ -505,6 +640,9 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
       useLiveTransforms.getState().clear(movingDoorNode.id)
       // Opening guides are wall-specific; clear them when over a roof face.
       clearOpeningGuides3D()
+      // On a roof face the real mesh is the preview — drop the free-follow ghost
+      // and reveal the node.
+      revealRealNode()
       if (currentHostId !== target.segment.id) {
         useScene.getState().updateNode(movingDoorNode.id, {
           position: target.position,
@@ -514,6 +652,7 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
           wallId: undefined,
           roofSegmentId: target.segment.id,
           roofFace: target.face.id,
+          visible: true,
         })
         markHostDirty(currentHostId)
         currentHostId = target.segment.id
@@ -531,7 +670,9 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
     const onRoofClick = (event: RoofEvent) => {
       if (committed) return
       const target = resolveRoofMoveTarget(event)
-      if (!target?.valid) return
+      // Shift force-places over a colliding roof-face target too (see onWallClick).
+      if (!target) return
+      if (!target.valid && event.nativeEvent?.shiftKey !== true) return
       committed = true
       const segmentId = target.segment.id
 
@@ -553,6 +694,7 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
           roofSegmentId: segmentId,
           roofFace: target.face.id,
           parentId: segmentId,
+          visible: true,
         })
         useScene.getState().createNode(node, segmentId as AnyNodeId)
         placedId = node.id
@@ -566,6 +708,7 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
           roofSegmentId: original.roofSegmentId,
           roofFace: original.roofFace,
           metadata: original.metadata,
+          visible: original.visible,
         })
         useScene.temporal.getState().resume()
 
@@ -578,6 +721,7 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
           roofSegmentId: segmentId,
           roofFace: target.face.id,
           metadata: {},
+          visible: true,
         })
 
         if (original.parentId && original.parentId !== segmentId) {
@@ -622,6 +766,7 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
           roofSegmentId: original.roofSegmentId,
           roofFace: original.roofFace,
           metadata: original.metadata,
+          visible: original.visible,
         })
         if (original.parentId) markHostDirty(original.parentId)
       }
@@ -633,8 +778,10 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
     const onPlacementDragPointerUp = (event: PointerEvent) => {
       if (!consumePlacementDragRelease(event)) return
       // Free-following over open floor can't commit (no wall). A wall hover
-      // target commits via commitToWall; a roof face via onRoofClick.
-      if (lastTarget?.valid && !freeFollowing) {
+      // target commits via commitToWall; a roof face via onRoofClick. Shift
+      // force-places over a colliding wall target (the tint stays red as a
+      // warning); read shift from this pointerup so it's current at commit.
+      if (lastTarget && !freeFollowing && (lastTarget.valid || event.shiftKey)) {
         commitToWall(lastTarget)
         return
       }
@@ -655,23 +802,30 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
       ) {
         return
       }
-      // Only act where a flip is meaningful — on a wall hover or while
-      // free-following. On a roof face leave it to the default R (no flip, no
-      // sfx) so the cue never fires without a visible effect.
-      const onWall = lastTarget !== null
-      if (!(onWall || freeFollowing)) return
+      // Ignore OS key-repeat so a held R doesn't flip many times per press.
+      if (e.repeat) return
       e.preventDefault()
+      // ALWAYS toggle the persistent flip intent — never a no-op. (The old gate
+      // dropped R before the first pointermove, so initial-placement R needed a
+      // second press.) Then re-render whatever preview is current so the flip
+      // shows live and matches what commit will write.
       sideOverride = sideOverride === 'front' ? 'back' : 'front'
       triggerSFX('sfx:item-rotate')
-      if (onWall) {
+      if (lastTarget) {
         // On a wall: re-resolve with the flipped side and re-preview.
-        const next = resolveMoveTarget(lastTarget!.event)
+        const next = resolveMoveTarget(lastTarget.event)
         if (next) {
           lastTarget = next
           applyPreview(next)
         }
+      } else if (lastFloorPoint) {
+        // Free-following: re-run at the same spot so the floating ghost rebuilds
+        // with the flipped side (its swing/hinge geometry depends on `side`).
+        freeFollowAt(lastFloorPoint[0], lastFloorPoint[1], -1)
       } else {
-        // Free-following on the level: flip the draft's facing in place.
+        // No preview yet (R pressed before the first pointermove at initial
+        // placement): flip the hidden node so the FIRST preview/commit already
+        // reflects the chosen side.
         useScene.getState().updateNode(movingDoorNode.id, {
           side: sideOverride,
           rotation: [0, sideOverride === 'back' ? Math.PI : 0, 0],
@@ -679,6 +833,18 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
       }
     }
 
+    // Shift toggles force-place. Track it live and re-run the on-wall preview so
+    // the tint flips green↔red the instant Shift is pressed/released, even with
+    // the pointer stationary — the ghost and the commit gate read the same
+    // `placeable`. (Commit gates still read shift fresh from their own event.)
+    const onShiftToggle = (e: KeyboardEvent) => {
+      if (e.key !== 'Shift') return
+      const held = e.type === 'keydown'
+      if (held === shiftHeld) return
+      shiftHeld = held
+      if (!committed && lastTarget) applyPreview(lastTarget)
+    }
+
     emitter.on('wall:enter', onWallEnter)
     emitter.on('wall:move', onWallMove)
     emitter.on('wall:click', onWallClick)
@@ -691,6 +857,8 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
     emitter.on('tool:cancel', onCancel)
     window.addEventListener('pointerup', onPlacementDragPointerUp)
     window.addEventListener('keydown', onKeyDown)
+    window.addEventListener('keydown', onShiftToggle)
+    window.addEventListener('keyup', onShiftToggle)
 
     return () => {
       const current = useScene.getState().nodes[movingDoorNode.id as AnyNodeId] as
@@ -711,9 +879,17 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
             roofSegmentId: original.roofSegmentId,
             roofFace: original.roofFace,
             metadata: original.metadata,
+            visible: original.visible,
           })
           if (original.parentId) markHostDirty(original.parentId)
         }
+      } else if (current && current.visible === false) {
+        // Safety net: a fresh (isNew) clone isn't marked `isTransient`, so the
+        // branch above skips it. If we unmount mid-free-follow it would be left
+        // hidden — reveal it so it never becomes an invisible orphan. (The
+        // `place-preset` movingNode subscription deletes a truly-cancelled
+        // clone separately.)
+        useScene.getState().updateNode(movingDoorNode.id, { visible: true })
       }
       useLiveTransforms.getState().clear(movingDoorNode.id)
       useAlignmentGuides.getState().clear()
@@ -731,6 +907,8 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
       emitter.off('tool:cancel', onCancel)
       window.removeEventListener('pointerup', onPlacementDragPointerUp)
       window.removeEventListener('keydown', onKeyDown)
+      window.removeEventListener('keydown', onShiftToggle)
+      window.removeEventListener('keyup', onShiftToggle)
     }
   }, [movingDoorNode, exitMoveMode])
 
@@ -747,9 +925,23 @@ const MoveDoorTool: React.FC<{ node: DoorNode }> = ({ node: movingDoorNode }) =>
   useEffect(() => () => edgesGeo.dispose(), [edgesGeo])
 
   return (
-    <group ref={cursorGroupRef} visible={false}>
-      <lineSegments geometry={edgesGeo} layers={EDITOR_LAYER} material={edgeMaterial} />
-    </group>
+    <>
+      <group ref={cursorGroupRef} visible={false}>
+        <lineSegments geometry={edgesGeo} layers={EDITOR_LAYER} material={edgeMaterial} />
+      </group>
+      {/* Placement ghost shown for the whole move (the real pale node stays
+          hidden): red off-wall / colliding, green on a valid wall. Uses the
+          moving node's own dimensions so the ghost matches its type. */}
+      {ghostPose && (
+        <group position={ghostPose.position} rotation-y={ghostPose.rotationY}>
+          <DoorPreview
+            invalid={ghostPose.tint === 'invalid'}
+            node={ghostNode}
+            valid={ghostPose.tint === 'valid'}
+          />
+        </group>
+      )}
+    </>
   )
 }
 

packages/nodes/src/door/preview.tsx

@@ -16,16 +16,24 @@ import type { DoorNode } from './schema'
  * The root mesh's layer is set to EDITOR_LAYER because the invisible hitbox
  * material on SCENE_LAYER would poison the WebGPU MRT pass (project gotcha).
  */
-const DoorPreview = ({ node, invalid }: { node: DoorNode; invalid?: boolean }) => {
+const DoorPreview = ({
+  node,
+  invalid,
+  valid,
+}: {
+  node: DoorNode
+  invalid?: boolean
+  valid?: boolean
+}) => {
   const mesh = useMemo(() => {
     const m = buildDoorPreviewMesh(node)
     m.layers.set(EDITOR_LAYER)
     return m
   }, [node.width, node.height, node.frameDepth, node.openingShape, node.doorType, node.leafCount])
 
-  // Ghost treatment (clone + tint + raycast-off) re-applies if `invalid`
-  // flips; its cleanup only disposes the clones it made.
-  useEffect(() => applyGhost(mesh, { invalid }), [mesh, invalid])
+  // Ghost treatment (clone + tint + raycast-off) re-applies if the tint flips;
+  // its cleanup only disposes the clones it made.
+  useEffect(() => applyGhost(mesh, { invalid, valid }), [mesh, invalid, valid])
 
   // Geometry is freshly built per `mesh` and owned here — dispose it only
   // when the mesh itself is replaced/unmounted, never on an `invalid` toggle.

packages/nodes/src/door/tool.tsx

@@ -74,13 +74,25 @@ const DoorTool: React.FC = () => {
 
   // Off-host floating ghost: the real door geometry follows the cursor over
   // the grid (tinted invalid). Mutually exclusive with the on-host draft —
-  // when a draft + wireframe is shown this is null and vice-versa.
+  // when a draft + wireframe is shown this is null and vice-versa. `side`
+  // carries the R-flip so the floating ghost faces the side that will be
+  // committed (its swing/hinge geometry depends on `side`).
   const [fallbackPose, setFallbackPose] = useState<{
     position: [number, number, number]
     rotationY: number
+    side: DoorNode['side']
   } | null>(null)
 
-  const ghostStub = useMemo(() => DoorNode.parse({ position: [0, 0, 0], rotation: [0, 0, 0] }), [])
+  // Ghost preview node — zeroed transform + the live facing side (rebuilds on R).
+  const ghostStub = useMemo(
+    () =>
+      DoorNode.parse({
+        position: [0, 0, 0],
+        rotation: [0, 0, 0],
+        side: fallbackPose?.side ?? 'front',
+      }),
+    [fallbackPose?.side],
+  )
 
   useEffect(() => {
     useScene.temporal.getState().pause()
@@ -98,6 +110,9 @@ const DoorTool: React.FC = () => {
     // re-applied to the last wall hover so the flip shows live before commit.
     let sideFlip = false
     let lastWallEvent: WallEvent | null = null
+    // Last open-floor cursor point (level-local X/Z) so an R-flip while
+    // free-following can re-render the floating ghost with the new facing.
+    let lastFloorPoint: [number, number, number] | null = null
 
     const getLevelId = () => useViewer.getState().selection.levelId
     const getLevelYOffset = () => {
@@ -149,9 +164,15 @@ const DoorTool: React.FC = () => {
 
     // Off-host fallback: hide the wireframe outline and float the real door
     // geometry (tinted invalid) at the cursor so the armed tool is visible.
+    // `sideFlip` (R) flips the facing: a back facing is a π yaw on the floating
+    // ghost, and the door swing/hinge geometry reads `side`.
     const showGhostAt = (position: [number, number, number]) => {
       if (cursorGroupRef.current) cursorGroupRef.current.visible = false
-      setFallbackPose({ position, rotationY: 0 })
+      setFallbackPose({
+        position,
+        rotationY: sideFlip ? Math.PI : 0,
+        side: sideFlip ? 'back' : 'front',
+      })
       useAlignmentGuides.getState().clear()
       clearOpeningGuides3D()
     }
@@ -176,13 +197,16 @@ const DoorTool: React.FC = () => {
       bypassSnap: boolean,
       ignoreId?: string,
     ) => {
+      // bypassSnap is set by Shift (see callers). Shift = free-place: land at the
+      // raw cursor but keep the along-wall guides visible. bypass (Alt) still
+      // hard-disables alignment.
       const localX = resolveWallSlideAlignment({
         wallNode: wall,
         rawLocalX,
         width,
         candidates: alignmentCandidates,
-        bypass,
-        bypassSnap,
+        bypass: bypass && !bypassSnap,
+        freePlace: bypassSnap,
       })
       const { clampedX, clampedY } = clampToWall(wall, localX, width, height)
       const valid = !hasWallChildOverlap(wall.id, clampedX, clampedY, width, height, ignoreId)
@@ -403,7 +427,8 @@ const DoorTool: React.FC = () => {
         bypassSnap,
         draftRef.current.id,
       )
-      if (!valid) return
+      // Shift force-places over a collision (the draft stays red as a warning).
+      if (!valid && !bypassSnap) return
 
       commitDoorAtWall(event.node, clampedX, clampedY, side, itemRotation)
       event.stopPropagation()
@@ -433,8 +458,9 @@ const DoorTool: React.FC = () => {
       hostKind = null
       lastWallEvent = null
       const [x, y, z] = event.localPosition
+      lastFloorPoint = [x, y + FALLBACK_HEIGHT / 2, z]
       destroyDraft()
-      showGhostAt([x, y + FALLBACK_HEIGHT / 2, z])
+      showGhostAt(lastFloorPoint)
     }
 
     // ── Roof-segment wall faces ─────────────────────────────────────
@@ -497,7 +523,9 @@ const DoorTool: React.FC = () => {
     const onRoofClick = (event: RoofEvent) => {
       if (!draftRef.current?.roofSegmentId) return
       const target = resolveRoofTarget(event)
-      if (!target?.valid) return
+      // Shift force-places over a colliding roof-face target (see onWallClick).
+      if (!target) return
+      if (!target.valid && event.nativeEvent?.shiftKey !== true) return
       const { segment, face, position } = target
 
       const draft = draftRef.current
@@ -568,18 +596,26 @@ const DoorTool: React.FC = () => {
     }
 
     // R flips the door's facing side mid-placement (front ↔ back), like the
-    // committed-selected R flip. Only meaningful while snapped to a wall (the
-    // off-wall ghost has no orientation), so it acts only then — re-applying
-    // the last wall hover so the snapped preview flips live.
+    // committed-selected R flip. ALWAYS toggles the persistent flip intent —
+    // never a no-op (the old `!lastWallEvent` guard dropped R off-wall and before
+    // the first wall hover, so it "needed two presses"). Then re-renders whatever
+    // preview is current so the flip shows live and matches commit.
     const onKeyDown = (e: KeyboardEvent) => {
       if (e.key !== 'r' && e.key !== 'R') return
-      if (!lastWallEvent) return
+      if (e.repeat) return
       const t = e.target as HTMLElement | null
       if (t && (t.tagName === 'INPUT' || t.tagName === 'TEXTAREA' || t.isContentEditable)) return
       e.preventDefault()
       sideFlip = !sideFlip
       triggerSFX('sfx:item-rotate')
-      onWallHover(lastWallEvent)
+      if (lastWallEvent) {
+        // On a wall: re-resolve + re-preview with the flipped side.
+        onWallHover(lastWallEvent)
+      } else if (lastFloorPoint) {
+        // Off-wall: re-render the floating ghost (showGhostAt reads `sideFlip`).
+        showGhostAt(lastFloorPoint)
+      }
+      // else: no preview yet — `sideFlip` is set, so the first hover/follow uses it.
     }
 
     emitter.on('wall:enter', onWallHover)

packages/nodes/src/shared/ghost-materials.ts

@@ -3,6 +3,7 @@
 import type { Material, Mesh, Object3D, Raycaster } from 'three'
 
 export const INVALID_GHOST_COLOR = 0xef_44_44
+export const VALID_GHOST_COLOR = 0x22_c5_5e
 
 const NO_RAYCAST = (_raycaster: Raycaster, _intersects: unknown[]) => {}
 
@@ -12,8 +13,11 @@ const NO_RAYCAST = (_raycaster: Raycaster, _intersects: unknown[]) => {}
  * Traverses the object tree, disables raycasting on all descendants (prevents
  * cursor-ray starvation), and clones visible mesh materials to set translucency.
  *
- * When `invalid` is true, sets color/emissive to INVALID_GHOST_COLOR and opacity ~0.4.
- * Otherwise sets opacity ~0.5 while preserving the original color.
+ * Tint by state:
+ *   - `invalid` (red, opacity ~0.4): off-host or colliding — can't place here.
+ *   - `valid` (green, opacity ~0.45): on a host and placeable — the "go" cue.
+ *   - neither (opacity ~0.5, original color): a plain translucent preview.
+ * `invalid` wins if both are passed.
  *
  * Skips: meshes whose material.visible === false (door/window root hitbox) and
  * children named 'cutout'.
@@ -21,11 +25,15 @@ const NO_RAYCAST = (_raycaster: Raycaster, _intersects: unknown[]) => {}
  * Returns cleanup that disposes only the cloned materials (never originals or geometry).
  *
  * @param root - The preview mesh tree (typically from buildDoorPreviewMesh / buildWindowPreviewMesh)
- * @param opts - { invalid?: boolean } whether to tint red for invalid placement
+ * @param opts - { invalid?, valid? } placement-state tint
  * @returns Cleanup function that disposes the cloned materials
  */
-export function applyGhost(root: Object3D, opts?: { invalid?: boolean }): () => void {
+export function applyGhost(
+  root: Object3D,
+  opts?: { invalid?: boolean; valid?: boolean },
+): () => void {
   const invalid = opts?.invalid ?? false
+  const valid = !invalid && (opts?.valid ?? false)
   const cloned: Material[] = []
 
   root.traverse((obj) => {
@@ -51,6 +59,12 @@ export function applyGhost(root: Object3D, opts?: { invalid?: boolean }): () =>
           INVALID_GHOST_COLOR,
         )
         clone.opacity = 0.4
+      } else if (valid) {
+        ;(clone as { color?: { setHex: (c: number) => void } }).color?.setHex(VALID_GHOST_COLOR)
+        ;(clone as { emissive?: { setHex: (c: number) => void } }).emissive?.setHex(
+          VALID_GHOST_COLOR,
+        )
+        clone.opacity = 0.45
       } else {
         clone.opacity = 0.5
       }

packages/nodes/src/shared/wall-attach-target.ts

@@ -5,6 +5,7 @@ import {
   getScaledDimensions,
   type ItemNode,
   nearestWallSegment,
+  useScene,
   WALL_SNAP_DISTANCE_M,
   type WallNode,
 } from '@pascal-app/core'
@@ -187,3 +188,104 @@ export function snapLocalXToNeighbors(args: {
 
   return bestDelta === null ? null : localX + bestDelta
 }
+
+/**
+ * Does a wall-hosted opening of `width × height` centred at `(clampedX,
+ * clampedY)` (wall-local) overlap any OTHER child of `wallId` (door / window /
+ * wall-mounted item)? AABB test in the wall's local face plane. `ignoreId`
+ * excludes the moving node itself. Returns `true` (blocked) if the wall is
+ * gone.
+ *
+ * Single source of truth for door + window placement collision — door-math and
+ * window-math had byte-identical copies of this. Y conventions differ per kind
+ * (items store bottom Y; doors/windows store centre Y), handled inline.
+ */
+export function hasWallChildOverlap(
+  wallId: string,
+  clampedX: number,
+  clampedY: number,
+  width: number,
+  height: number,
+  ignoreId?: string,
+): boolean {
+  const nodes = useScene.getState().nodes
+  const wallNode = nodes[wallId as AnyNodeId] as WallNode | undefined
+  if (!wallNode) return true
+  const halfW = width / 2
+  const halfH = height / 2
+  const newBottom = clampedY - halfH
+  const newTop = clampedY + halfH
+  const newLeft = clampedX - halfW
+  const newRight = clampedX + halfW
+
+  for (const childId of Array.isArray(wallNode.children) ? wallNode.children : []) {
+    if (childId === ignoreId) continue
+    const child = nodes[childId as AnyNodeId]
+    if (!child) continue
+
+    let childLeft: number
+    let childRight: number
+    let childBottom: number
+    let childTop: number
+
+    if (child.type === 'item') {
+      const item = child as ItemNode
+      if (item.asset.attachTo !== 'wall' && item.asset.attachTo !== 'wall-side') continue
+      const [w, h] = getScaledDimensions(item)
+      childLeft = item.position[0] - w / 2
+      childRight = item.position[0] + w / 2
+      childBottom = item.position[1] // items store bottom Y
+      childTop = item.position[1] + h
+    } else if (child.type === 'window') {
+      const win = child as { position: [number, number, number]; width: number; height: number }
+      childLeft = win.position[0] - win.width / 2
+      childRight = win.position[0] + win.width / 2
+      childBottom = win.position[1] - win.height / 2 // windows store centre Y
+      childTop = win.position[1] + win.height / 2
+    } else if (child.type === 'door') {
+      const door = child as { position: [number, number, number]; width: number; height: number }
+      childLeft = door.position[0] - door.width / 2
+      childRight = door.position[0] + door.width / 2
+      childBottom = door.position[1] - door.height / 2 // doors store centre Y
+      childTop = door.position[1] + door.height / 2
+    } else {
+      continue
+    }
+
+    const xOverlap = newLeft < childRight && newRight > childLeft
+    const yOverlap = newBottom < childTop && newTop > childBottom
+    if (xOverlap && yOverlap) return true
+  }
+
+  return false
+}
+
+/** Placement state for a wall-hosted opening — the SINGLE decision the preview
+ *  tint and the commit gate both consume so they can never disagree. */
+export type OpeningPlacement = {
+  /** Geometric overlap with another wall child (independent of modifiers). */
+  collides: boolean
+  /** May the opening be committed here? `true` unless it collides and the user
+   *  isn't force-placing. */
+  placeable: boolean
+  /** Ghost tint: green when placeable, red when not. */
+  tint: 'valid' | 'invalid'
+}
+
+/**
+ * Resolve the placement state from the raw collision result and whether the
+ * user is force-placing (Shift). Force-place lifts the collision block, so the
+ * opening becomes placeable AND the tint goes green — the preview and the
+ * commit gate stay in lockstep because both read this one result.
+ */
+export function resolveOpeningPlacement(args: {
+  collides: boolean
+  forcePlace: boolean
+}): OpeningPlacement {
+  const placeable = !args.collides || args.forcePlace
+  return {
+    collides: args.collides,
+    placeable,
+    tint: placeable ? 'valid' : 'invalid',
+  }
+}

packages/nodes/src/shared/wall-opening-alignment.ts

@@ -23,6 +23,12 @@ const MIN_AXIS_COMPONENT = 0.5
  * guide on bypass / no-match. Returns the localX to use (X-clamped to the wall
  * given `width`). `bypass` disables alignment; `bypassSnap` also skips the
  * half-metre fallback.
+ *
+ * `freePlace` (Shift) is the "place anywhere, but still show me where I'd
+ * align" mode: the opening lands at the EXACT raw cursor (no grid snap, no
+ * jump-to-guide), yet the alignment guides are still computed and shown so the
+ * user keeps the visual reference while overriding the magnetic pull. It
+ * supersedes `bypass`/`bypassSnap` when set.
  */
 export function resolveWallSlideAlignment(args: {
   wallNode: WallNode
@@ -31,9 +37,55 @@ export function resolveWallSlideAlignment(args: {
   candidates: readonly AlignmentAnchor[]
   bypass: boolean
   bypassSnap?: boolean
+  freePlace?: boolean
 }): number {
-  const { wallNode, rawLocalX, width, candidates, bypass, bypassSnap = false } = args
-  const base = bypassSnap ? rawLocalX : snapToHalf(rawLocalX)
+  const {
+    wallNode,
+    rawLocalX,
+    width,
+    candidates,
+    bypass,
+    bypassSnap = false,
+    freePlace = false,
+  } = args
+  const base = bypassSnap || freePlace ? rawLocalX : snapToHalf(rawLocalX)
+
+  const dxAxis = wallNode.end[0] - wallNode.start[0]
+  const dzAxis = wallNode.end[1] - wallNode.start[1]
+  const axisLength = Math.sqrt(dxAxis * dxAxis + dzAxis * dzAxis)
+
+  // Shift / free-place: land at the raw cursor but still publish the guides so
+  // the user sees alignment relationships without being snapped to them. The
+  // guides are re-resolved at the freely-placed point so they connect to the
+  // opening, not the snap target.
+  if (freePlace) {
+    if (candidates.length === 0 || axisLength < 1e-6) {
+      useAlignmentGuides.getState().clear()
+      return base
+    }
+    const c = dxAxis / axisLength
+    const s = dzAxis / axisLength
+    const placedX = Math.max(width / 2, Math.min(axisLength - width / 2, base))
+    const shown = resolveAlignment({
+      moving: [
+        {
+          nodeId: '__wall-opening-draft__',
+          kind: 'corner',
+          x: wallNode.start[0] + placedX * c,
+          z: wallNode.start[1] + placedX * s,
+        },
+      ],
+      candidates,
+      threshold: WALL_OPENING_ALIGNMENT_THRESHOLD_M,
+    })
+    const axisGuides = shown.guides.filter(
+      (g) => Math.abs(g.axis === 'x' ? c : s) >= MIN_AXIS_COMPONENT,
+    )
+    if (axisGuides.length === 0) useAlignmentGuides.getState().clear()
+    else useAlignmentGuides.getState().set(axisGuides)
+    return placedX
+  }
+
   if (bypass || candidates.length === 0) {
     useAlignmentGuides.getState().clear()
     return base

packages/nodes/src/window/floor-projection.tsx

@@ -0,0 +1,111 @@
+'use client'
+
+import { EDITOR_LAYER } from '@pascal-app/editor'
+import { useEffect, useMemo } from 'react'
+import { BufferGeometry, Float32BufferAttribute, LineSegments } from 'three'
+import { LineBasicNodeMaterial } from 'three/webgpu'
+
+/**
+ * Floor "shadow" projection for a window during placement / move.
+ *
+ * Windows sit elevated above the floor, so over open ground (and on a wall)
+ * it's hard to read where the window actually is in plan. This draws its
+ * projection on the floor: a small footprint segment directly below the window
+ * (its plan extent along the wall) plus a DASHED vertical line dropping from the
+ * window centre to that footprint — like a shadow tether. Placement aid only;
+ * never shown on a committed window.
+ *
+ * Rendered in WORLD space (the tool positions the ghost in world space too), so
+ * it's mounted as a sibling of the ghost — NOT inside the ghost's rotated/offset
+ * group. `centerY` is the window centre's world Y; `floorY` is the level floor.
+ */
+
+const FOOTPRINT_COLOR = 0x38_bd_f8
+const DROP_COLOR = 0x38_bd_f8
+
+const footprintMaterial = new LineBasicNodeMaterial({
+  color: FOOTPRINT_COLOR,
+  transparent: true,
+  opacity: 0.85,
+  depthWrite: false,
+})
+const dropMaterial = new LineBasicNodeMaterial({
+  color: DROP_COLOR,
+  transparent: true,
+  opacity: 0.6,
+  depthWrite: false,
+})
+
+// Dash geometry for the vertical drop: alternating on/off segments so it reads
+// as a dashed tether without a dashed-line material (unavailable in three/webgpu).
+const DASH = 0.12
+const GAP = 0.08
+
+export function WindowFloorProjection({
+  centerX,
+  centerZ,
+  centerY,
+  floorY,
+  width,
+  rotationY,
+}: {
+  centerX: number
+  centerZ: number
+  centerY: number
+  floorY: number
+  width: number
+  rotationY: number
+}) {
+  // Footprint: a short segment of length `width` along the window's wall axis,
+  // centred under the window on the floor. The window faces `rotationY` about Y
+  // (its width runs along the wall), so the along-wall direction is
+  // (cos, -sin) in XZ.
+  const footprint = useMemo(() => {
+    const half = width / 2
+    const dirX = Math.cos(rotationY)
+    const dirZ = -Math.sin(rotationY)
+    const position = new Float32BufferAttribute(new Float32Array(6), 3)
+    const geometry = new BufferGeometry()
+    geometry.setAttribute('position', position)
+    const line = new LineSegments(geometry, footprintMaterial)
+    line.frustumCulled = false
+    line.layers.set(EDITOR_LAYER)
+    line.renderOrder = 1000
+    line.raycast = () => {}
+    position.setXYZ(0, centerX - dirX * half, floorY + 0.002, centerZ - dirZ * half)
+    position.setXYZ(1, centerX + dirX * half, floorY + 0.002, centerZ + dirZ * half)
+    position.needsUpdate = true
+    return line
+  }, [centerX, centerZ, floorY, width, rotationY])
+
+  // Dashed vertical tether from the window centre down to the footprint.
+  const drop = useMemo(() => {
+    const span = Math.max(centerY - floorY, 0)
+    const segs: number[] = []
+    let y = floorY
+    while (y < floorY + span) {
+      const top = Math.min(y + DASH, floorY + span)
+      segs.push(centerX, y, centerZ, centerX, top, centerZ)
+      y += DASH + GAP
+    }
+    const position = new Float32BufferAttribute(new Float32Array(segs), 3)
+    const geometry = new BufferGeometry()
+    geometry.setAttribute('position', position)
+    const line = new LineSegments(geometry, dropMaterial)
+    line.frustumCulled = false
+    line.layers.set(EDITOR_LAYER)
+    line.renderOrder = 1000
+    line.raycast = () => {}
+    return line
+  }, [centerX, centerZ, centerY, floorY])
+
+  useEffect(() => () => footprint.geometry.dispose(), [footprint])
+  useEffect(() => () => drop.geometry.dispose(), [drop])
+
+  return (
+    <>
+      <primitive object={footprint} />
+      <primitive object={drop} />
+    </>
+  )
+}

packages/nodes/src/window/floorplan-move.ts

@@ -8,15 +8,16 @@ import {
   WallNode as WallNodeSchema,
   type WindowNode,
 } from '@pascal-app/core'
-import { snapToHalf, usePlacementPreview } from '@pascal-app/editor'
+import { snapToHalf, triggerSFX, usePlacementPreview } from '@pascal-app/editor'
 import { createFloorplanCursorResolver } from '../shared/floorplan-cursor'
 import { getOpeningHostLevelId, getRoofHostedOpeningPlanPoint } from '../shared/roof-opening-host'
 import {
   findClosestWallInPlan,
   projectWallLocalPointToPlan,
+  resolveOpeningPlacement,
   snapLocalXToNeighbors,
 } from '../shared/wall-attach-target'
-import { clampToWall, hasWallChildOverlap } from './window-math'
+import { clampToWall, DEFAULT_WINDOW_SILL_M, hasWallChildOverlap } from './window-math'
 
 /**
  * 2D floor-plan move handler for window. Same shape as door (see
@@ -56,8 +57,8 @@ export const windowFloorplanMoveTarget: FloorplanMoveTarget<WindowNode> = ({ nod
   // created at y=0, which would sit the window's centre on the floor (half
   // below ground); default those to a realistic sill so it floats above
   // the floor in 2D too. Same rule as the 3D `MoveWindowTool` (`getSillCenterY`).
-  const DEFAULT_SILL = 0.9
-  const startLocalY = node.position[1] > 0.1 ? node.position[1] : DEFAULT_SILL + node.height / 2
+  const startLocalY =
+    node.position[1] > 0.1 ? node.position[1] : DEFAULT_WINDOW_SILL_M + node.height / 2
 
   // Track the last successful placement so `commit()` can write it
   // atomically — same deterministic-commit fix as `doorFloorplanMoveTarget`.
@@ -82,6 +83,23 @@ export const windowFloorplanMoveTarget: FloorplanMoveTarget<WindowNode> = ({ nod
   // See `doorFloorplanMoveTarget`: off-wall the window free-follows the cursor
   // as a ghost and isn't committable (it needs a wall). Starts true.
   let onWall = true
+  // Shift force-place (last apply's modifier) — lets `canCommit` allow an
+  // overlapping placement, matching the 3D move.
+  let forcePlace = false
+
+  // Move SFX — parity with the 3D `MoveWindowTool` (see `doorFloorplanMoveTarget`):
+  // ONE soft `sfx:grid-snap` click per grid step, identical free-following or on a
+  // wall, keyed on the RAW cursor. No separate floor→wall cue (that was the
+  // "double"). 2D `apply` runs once per pointermove, so the step-key dedup suffices.
+  const STEP_M = 0.1
+  let lastStepKey: string | null = null
+  const tickGridStep = (...coords: number[]) => {
+    const key = coords.map((c) => Math.round(c / STEP_M)).join(',')
+    if (key !== lastStepKey) {
+      lastStepKey = key
+      triggerSFX('sfx:grid-snap')
+    }
+  }
 
   const freeFollow = (planPoint: readonly [number, number]) => {
     onWall = false
@@ -95,14 +113,22 @@ export const windowFloorplanMoveTarget: FloorplanMoveTarget<WindowNode> = ({ nod
       end: [planPoint[0] + half, planPoint[1]],
       thickness: 0.1,
     })
+    // Reflect the R-flip on the floating ghost so it faces the side that will
+    // be committed (see `doorFloorplanMoveTarget.freeFollow`).
+    const ghostSide: WindowNode['side'] = flipped
+      ? node.side === 'front'
+        ? 'back'
+        : 'front'
+      : node.side
     const ghost = {
       ...node,
+      side: ghostSide,
       parentId: wall.id,
       wallId: wall.id,
       roofSegmentId: undefined,
       roofFace: undefined,
       position: [half, startLocalY, 0] as [number, number, number],
-      rotation: [0, 0, 0] as [number, number, number],
+      rotation: [0, flipped ? Math.PI : 0, 0] as [number, number, number],
       visible: true,
     } as WindowNode
     usePlacementPreview.getState().set(ghost, wall)
@@ -116,6 +142,7 @@ export const windowFloorplanMoveTarget: FloorplanMoveTarget<WindowNode> = ({ nod
     },
     apply({ planPoint, modifiers }) {
       lastApply = { planPoint, modifiers }
+      forcePlace = modifiers.shiftKey === true
       // Drop any stale live transform left by the 3D `MoveWindowTool` — see
       // `doorFloorplanMoveTarget.apply`. Without this the 2D registry layer
       // keeps rendering the window at the 3D tool's last hover (it prefers
@@ -129,6 +156,8 @@ export const windowFloorplanMoveTarget: FloorplanMoveTarget<WindowNode> = ({ nod
       const resolvedPlanPoint = resolveCursor(planPoint)
       const hit = findClosestWallInPlan(resolvedPlanPoint, nodes, startLevelId)
       if (!hit) {
+        // Off any wall — free-follow. Click per grid cell over open floor.
+        tickGridStep(resolvedPlanPoint[0], resolvedPlanPoint[1])
         freeFollow(resolvedPlanPoint)
         return
       }
@@ -160,6 +189,11 @@ export const windowFloorplanMoveTarget: FloorplanMoveTarget<WindowNode> = ({ nod
         node.height,
       )
 
+      // One click per grid step, keyed on the RAW along-wall cursor (`hit.localX`)
+      // so the wall slide ticks at the same cadence as the off-wall ghost — same
+      // SFX, no separate snap cue.
+      tickGridStep(hit.localX)
+
       const side: WindowNode['side'] = flipped
         ? hit.side === 'front'
           ? 'back'
@@ -192,7 +226,9 @@ export const windowFloorplanMoveTarget: FloorplanMoveTarget<WindowNode> = ({ nod
       if (!onWall) return false
       const live = useScene.getState().nodes[node.id as AnyNodeId] as WindowNode | undefined
       if (!live || live.type !== 'window') return false
-      const overlapping = hasWallChildOverlap(
+      // Block on overlap UNLESS Shift force-places — same `placeable` rule as
+      // the 3D move + the shared `resolveOpeningPlacement`.
+      const collides = hasWallChildOverlap(
         live.parentId as string,
         live.position[0],
         live.position[1],
@@ -200,7 +236,7 @@ export const windowFloorplanMoveTarget: FloorplanMoveTarget<WindowNode> = ({ nod
         live.height,
         live.id,
       )
-      return !overlapping
+      return resolveOpeningPlacement({ collides, forcePlace }).placeable
     },
     commit() {
       // Own the atomic write so the overlay takes the deterministic

packages/nodes/src/window/move-tool.tsx

@@ -14,7 +14,6 @@ import {
   WindowNode,
 } from '@pascal-app/core'
 import {
-  calculateCursorRotation,
   calculateItemRotation,
   consumePlacementDragRelease,
   EDITOR_LAYER,
@@ -27,7 +26,7 @@ import {
   useEditor,
 } from '@pascal-app/editor'
 import { useViewer } from '@pascal-app/viewer'
-import { useCallback, useEffect, useMemo, useRef } from 'react'
+import { useCallback, useEffect, useMemo, useRef, useState } from 'react'
 import { BoxGeometry, EdgesGeometry, type Group } from 'three'
 import { LineBasicNodeMaterial } from 'three/webgpu'
 import {
@@ -40,8 +39,16 @@ import {
   type RoofWallOpeningTarget,
   resolveRoofWallOpeningTarget,
 } from '../shared/roof-wall-opening-placement'
+import { resolveOpeningPlacement } from '../shared/wall-attach-target'
 import { resolveWallSlideAlignment } from '../shared/wall-opening-alignment'
-import { clampToWall, hasWallChildOverlap, wallLocalToWorld } from './window-math'
+import { WindowFloorProjection } from './floor-projection'
+import WindowPreview from './preview'
+import {
+  clampToWall,
+  DEFAULT_WINDOW_SILL_M,
+  hasWallChildOverlap,
+  wallLocalToWorld,
+} from './window-math'
 
 const edgeMaterial = new LineBasicNodeMaterial({
   color: 0xef_44_44,
@@ -65,6 +72,38 @@ const edgeMaterial = new LineBasicNodeMaterial({
 const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode }) => {
   const cursorGroupRef = useRef<Group>(null!)
 
+  // The window preview ghost. Shown for the WHOLE move so the user always sees
+  // a translucent window tinted by placement state — red off-wall or colliding,
+  // green on a valid wall. The real node stays hidden until commit (the wall
+  // still cuts its hole from the node data). `null` = not previewing. See the
+  // matching `WindowPreview` tint and `MoveDoorTool` for the full rationale.
+  const [ghostPose, setGhostPose] = useState<{
+    position: [number, number, number]
+    rotationY: number
+    tint: 'valid' | 'invalid'
+    // Level floor world-Y, for the floor "shadow" projection (drop-line + footprint).
+    floorY: number
+    // Live facing side — R-flip changes it and the window geometry depends on it,
+    // so the ghost must rebuild with the live side (see `MoveDoorTool`).
+    side: WindowNode['side']
+  } | null>(null)
+
+  // Ghost preview node: the moving window with a zeroed transform + the live
+  // facing side (the ghost is positioned by the `<group position>` wrapper;
+  // `updateWindowMesh` bakes the node's own position/rotation in, so passing the
+  // live node would double-offset). Rebuilds on an R-flip so the preview matches
+  // what commit will place.
+  const ghostSide = ghostPose?.side ?? movingWindowNode.side
+  const ghostNode = useMemo(
+    () => ({
+      ...movingWindowNode,
+      side: ghostSide,
+      position: [0, 0, 0] as [number, number, number],
+      rotation: [0, 0, 0] as [number, number, number],
+    }),
+    [movingWindowNode, ghostSide],
+  )
+
   const exitMoveMode = useCallback(() => {
     useEditor.getState().setMovingNode(null)
   }, [])
@@ -91,6 +130,8 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
       roofSegmentId: movingWindowNode.roofSegmentId,
       roofFace: movingWindowNode.roofFace,
       metadata: movingWindowNode.metadata,
+      // Free-follow hides the node (visible:false); revert paths restore this.
+      visible: movingWindowNode.visible,
     }
 
     // In move mode (existing window) mark it transient so its mesh skips the live wall CSG
@@ -113,6 +154,29 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
     // mesh event owns the same pointermove — that's the only thing that snaps.
     let freeFollowing = false
     let lastMeshEventTime = -1
+    // Last open-floor cursor point (level-local X/Z), so an R-flip while free-
+    // following can re-run the ghost at the same spot with the new facing.
+    let lastFloorPoint: [number, number] | null = null
+    // Live Shift state (force-place) — lets the preview tint re-evaluate when
+    // Shift is pressed/released with the pointer stationary (see `MoveDoorTool`).
+    let shiftHeld = false
+    // Movement SFX: ONE soft `sfx:grid-snap` click per grid step — identical
+    // whether free-following over floor or sliding along a wall (the user's
+    // ask). Always keyed on the RAW cursor (continuous ~0.1m cadence), never the
+    // snapped along-wall value. Guards: `lastStepKey` (cell change) +
+    // `lastTickFrame` (one tick per DOM pointermove). No separate snap cue — a
+    // distinct floor→wall sound was the "double" the user heard. See `MoveDoorTool`.
+    const STEP_M = 0.1
+    let lastStepKey: string | null = null
+    let lastTickFrame = -1
+    const tickGridStep = (frame: number, ...coords: number[]) => {
+      if (frame === lastTickFrame) return
+      const key = coords.map((c) => Math.round(c / STEP_M)).join(',')
+      if (key === lastStepKey) return
+      lastStepKey = key
+      lastTickFrame = frame
+      triggerSFX('sfx:grid-snap')
+    }
     // The window's chosen facing side. R flips it mid-placement (front ↔ back),
     // matching the committed-selected R flip. Initialised from the moving node.
     let sideOverride: WindowNode['side'] = movingWindowNode.side
@@ -128,7 +192,6 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
       wallId: string
       side: WindowNode['side']
       itemRotation: number
-      cursorRotation: number
       clampedX: number
       clampedY: number
       valid: boolean
@@ -160,12 +223,11 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
     // Sill-center height used while the window isn't on a wall (free-follow and
     // proximity). Fresh preset clones are created at position [0,0,0], which
     // would bury half the window below the floor; default such windows to a
-    // ~0.9m sill so the ghost floats at a realistic height. An existing window
-    // keeps its own sill.
-    const DEFAULT_SILL = 0.9
+    // small sill so the ghost floats slightly above the ground. An existing
+    // window keeps its own sill.
     const getSillCenterY = () => {
       const y = movingWindowNode.position[1]
-      return y > 0.1 ? y : DEFAULT_SILL + movingWindowNode.height / 2
+      return y > 0.1 ? y : DEFAULT_WINDOW_SILL_M + movingWindowNode.height / 2
     }
     const getSlabElevation = (wallEvent: WallEvent) =>
       spatialGridManager.getSlabElevationForWall(
@@ -178,6 +240,7 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
       if (cursorGroupRef.current) cursorGroupRef.current.visible = false
       useAlignmentGuides.getState().clear()
       clearOpeningGuides3D()
+      setGhostPose(null)
     }
 
     // Alignment candidates — anchors of every OTHER alignable object (the
@@ -214,8 +277,6 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
       const side = sideOverride ?? faceSide
       const rotationOffset = side !== faceSide ? Math.PI : 0
       const itemRotation = calculateItemRotation(event.normal) + rotationOffset
-      const cursorRotation =
-        calculateCursorRotation(event.normal, event.node.start, event.node.end) + rotationOffset
 
       const rawLocalX = event.localPosition[0]
       const rawLocalY = event.localPosition[1]
@@ -256,8 +317,10 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
         rawLocalX: targetLocalX,
         width: movingWindowNode.width,
         candidates: alignmentCandidates,
-        bypass: event.nativeEvent?.altKey === true || event.nativeEvent?.shiftKey === true,
-        bypassSnap: event.nativeEvent?.shiftKey === true,
+        // Alt still hard-disables alignment (no guides). Shift = free-place:
+        // land at the raw cursor but keep showing the along-wall guides.
+        bypass: event.nativeEvent?.altKey === true,
+        freePlace: event.nativeEvent?.shiftKey === true,
       })
       const { clampedX, clampedY } = clampToWall(
         event.node,
@@ -281,7 +344,6 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
         wallId: event.node.id,
         side,
         itemRotation,
-        cursorRotation,
         clampedX,
         clampedY,
         valid,
@@ -290,6 +352,14 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
     }
 
     const applyPreview = (target: NonNullable<typeof lastTarget>) => {
+      // Same click as the off-wall ghost: one grid-snap tick per grid step,
+      // keyed on the RAW cursor along-wall position (not the snapped clampedX).
+      // Per-frame guard collapses duplicate wall events on the same pointermove.
+      tickGridStep(target.event.nativeEvent?.timeStamp ?? -1, target.event.localPosition[0])
+      // Keep the REAL node hidden and show a tinted ghost in the wall opening —
+      // green when placeable, red when it collides — matching the free-follow
+      // ghost so validity reads at a glance (see MoveDoorTool). The node position
+      // is still written so the wall cuts the hole at the right spot.
       if (currentHostId !== target.wallId) {
         useScene.getState().updateNode(movingWindowNode.id, {
           position: [target.clampedX, target.clampedY, 0],
@@ -299,6 +369,7 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
           wallId: target.wallId,
           roofSegmentId: undefined,
           roofFace: undefined,
+          visible: false,
         })
         markHostDirty(currentHostId)
         currentHostId = target.wallId
@@ -316,17 +387,28 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
       })
       markHostDirtyThrottled(target.wallId)
 
-      updateCursor(
-        wallLocalToWorld(
+      if (cursorGroupRef.current) cursorGroupRef.current.visible = false
+      const placement = resolveOpeningPlacement({ collides: !target.valid, forcePlace: shiftHeld })
+      // Ghost world yaw must equal the committed wall-CHILD's world yaw
+      // (-wallAngle + itemRotation); `cursorRotation` is π off here. See
+      // `MoveDoorTool.applyPreview`.
+      const wallAngle = Math.atan2(
+        target.wallNode.end[1] - target.wallNode.start[1],
+        target.wallNode.end[0] - target.wallNode.start[0],
+      )
+      setGhostPose({
+        position: wallLocalToWorld(
           target.wallNode,
           target.clampedX,
           target.clampedY,
           getLevelYOffset(),
           getSlabElevation(target.event),
         ),
-        target.cursorRotation,
-        target.valid,
-      )
+        rotationY: target.itemRotation - wallAngle,
+        tint: placement.tint,
+        floorY: getLevelYOffset() + getSlabElevation(target.event),
+        side: target.side,
+      })
 
       publishOpeningGuidesForWallEvent({
         wall: target.wallNode,
@@ -410,6 +492,8 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
           parentId: target.wallId,
           roofSegmentId: undefined,
           roofFace: undefined,
+          // Hidden during free-follow; the committed window must be visible.
+          visible: true,
         })
         useScene.getState().createNode(node, target.wallId as AnyNodeId)
         placedId = node.id
@@ -425,6 +509,7 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
           roofSegmentId: original.roofSegmentId,
           roofFace: original.roofFace,
           metadata: original.metadata,
+          visible: original.visible,
         })
         useScene.temporal.getState().resume()
 
@@ -436,6 +521,7 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
           wallId: target.wallId,
           roofSegmentId: undefined,
           metadata: {},
+          visible: true,
         })
 
         if (original.parentId && original.parentId !== target.wallId) {
@@ -462,7 +548,11 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
       if (event.node.parentId !== getLevelId()) return
 
       const target = lastTarget?.wallId === event.node.id ? lastTarget : resolveMoveTarget(event)
-      if (!target?.valid) return
+      // Shift force-places: commit even when the window overlaps another opening.
+      // The preview keeps its red invalid tint as a warning; Shift just lifts the
+      // commit block. Read shift from THIS event so it's never stale at commit.
+      if (!target) return
+      if (!target.valid && event.nativeEvent?.shiftKey !== true) return
       commitToWall(target)
       event.stopPropagation()
     }
@@ -480,13 +570,28 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
       lastRoofEvent = null
     }
 
-    // Free-follow: the window rides the cursor over empty floor, parented to
-    // the level like an item node, kept at a sensible sill height. No wall to
-    // attach to, so it is not committable here.
-    const freeFollowAt = (localX: number, localZ: number) => {
+    // Reveal the real window node + drop the ghost. Used by the roof-face path,
+    // which previews with the real mesh (the ghost-tint flow is wall-specific).
+    const revealRealNode = () => {
+      setGhostPose(null)
+      const live = useScene.getState().nodes[movingWindowNode.id as AnyNodeId] as
+        | WindowNode
+        | undefined
+      if (live && live.visible === false) {
+        useScene.getState().updateNode(movingWindowNode.id, { visible: true })
+      }
+    }
+
+    // Free-follow: over open floor there's no wall to host the window, so hide
+    // the real (pale, near-invisible-on-grid) node and float a red translucent
+    // ghost at the cursor — same treatment the raw `WindowTool` build path uses.
+    const freeFollowAt = (localX: number, localZ: number, frame: number) => {
       freeFollowing = true
       lastTarget = null
       lastRoofEvent = null
+      // Click per grid cell as the ghost slides over open floor (X+Z) — the
+      // same `tickGridStep` the on-wall slide uses, so both feel identical.
+      tickGridStep(frame, localX, localZ)
       hideCursor()
       useLiveTransforms.getState().clear(movingWindowNode.id)
       const levelId = getLevelId()
@@ -503,6 +608,7 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
           wallId: undefined,
           roofSegmentId: undefined,
           roofFace: undefined,
+          visible: false,
         })
         currentHostId = levelId
       } else {
@@ -510,8 +616,18 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
           position: [localX, sillCenterY, localZ],
           rotation: [0, yaw, 0],
           side: sideOverride,
+          visible: false,
         })
       }
+      // Float the red (invalid — no wall) ghost at the cursor, level-Y lifted to
+      // the sill center (sideOverride carries the R-flip so the ghost matches).
+      setGhostPose({
+        position: [localX, getLevelYOffset() + sillCenterY, localZ],
+        rotationY: yaw,
+        tint: 'invalid',
+        floorY: getLevelYOffset(),
+        side: sideOverride,
+      })
     }
 
     const onGridMove = (event: GridEvent) => {
@@ -523,7 +639,8 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
       // snapping engages only when the cursor ray actually hovers a wall.
       if (event.nativeEvent?.timeStamp === lastMeshEventTime) return
       const [x, , z] = event.localPosition
-      freeFollowAt(x, z)
+      lastFloorPoint = [x, z]
+      freeFollowAt(x, z, event.nativeEvent?.timeStamp ?? -1)
     }
 
     // ── Roof-segment wall faces ─────────────────────────────────────
@@ -564,6 +681,8 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
       useLiveTransforms.getState().clear(movingWindowNode.id)
       // Opening guides are wall-specific; clear them when over a roof face.
       clearOpeningGuides3D()
+      // On a roof face the real mesh is the preview — drop the ghost + reveal.
+      revealRealNode()
       if (currentHostId !== target.segment.id) {
         useScene.getState().updateNode(movingWindowNode.id, {
           position: target.position,
@@ -573,6 +692,7 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
           wallId: undefined,
           roofSegmentId: target.segment.id,
           roofFace: target.face.id,
+          visible: true,
         })
         markHostDirty(currentHostId)
         currentHostId = target.segment.id
@@ -590,7 +710,9 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
     const onRoofClick = (event: RoofEvent) => {
       if (committed) return
       const target = resolveRoofMoveTarget(event)
-      if (!target?.valid) return
+      // Shift force-places over a colliding roof-face target too (see onWallClick).
+      if (!target) return
+      if (!target.valid && event.nativeEvent?.shiftKey !== true) return
       committed = true
       const segmentId = target.segment.id
 
@@ -613,6 +735,7 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
           roofSegmentId: segmentId,
           roofFace: target.face.id,
           parentId: segmentId,
+          visible: true,
         })
         useScene.getState().createNode(node, segmentId as AnyNodeId)
         placedId = node.id
@@ -626,6 +749,7 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
           roofSegmentId: original.roofSegmentId,
           roofFace: original.roofFace,
           metadata: original.metadata,
+          visible: original.visible,
         })
         useScene.temporal.getState().resume()
 
@@ -638,6 +762,7 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
           roofSegmentId: segmentId,
           roofFace: target.face.id,
           metadata: {},
+          visible: true,
         })
 
         if (original.parentId && original.parentId !== segmentId) {
@@ -682,6 +807,7 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
           roofSegmentId: original.roofSegmentId,
           roofFace: original.roofFace,
           metadata: original.metadata,
+          visible: original.visible,
         })
         if (original.parentId) markHostDirty(original.parentId)
       }
@@ -693,8 +819,10 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
     const onPlacementDragPointerUp = (event: PointerEvent) => {
       if (!consumePlacementDragRelease(event)) return
       // Free-following over open floor can't commit (no wall). A wall hover
-      // target commits via commitToWall; a roof face via onRoofClick.
-      if (lastTarget?.valid && !freeFollowing) {
+      // target commits via commitToWall; a roof face via onRoofClick. Shift
+      // force-places over a colliding wall target (tint stays red as a warning);
+      // read shift from this pointerup so it's current at commit.
+      if (lastTarget && !freeFollowing && (lastTarget.valid || event.shiftKey)) {
         commitToWall(lastTarget)
         return
       }
@@ -714,18 +842,27 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
       ) {
         return
       }
-      const onWall = lastTarget !== null
-      if (!(onWall || freeFollowing)) return
+      // Ignore OS key-repeat so a held R doesn't flip many times per press.
+      if (e.repeat) return
       e.preventDefault()
+      // ALWAYS toggle the persistent flip intent — never a no-op (the old gate
+      // dropped R before the first pointermove). Then re-render the current
+      // preview so the flip shows live and matches commit. See `MoveDoorTool`.
       sideOverride = sideOverride === 'front' ? 'back' : 'front'
       triggerSFX('sfx:item-rotate')
-      if (onWall) {
-        const next = resolveMoveTarget(lastTarget!.event)
+      if (lastTarget) {
+        const next = resolveMoveTarget(lastTarget.event)
         if (next) {
           lastTarget = next
           applyPreview(next)
         }
+      } else if (lastFloorPoint) {
+        // Free-following: re-run at the same spot so the floating ghost rebuilds
+        // with the flipped side.
+        freeFollowAt(lastFloorPoint[0], lastFloorPoint[1], -1)
       } else {
+        // No preview yet (R before the first pointermove): flip the hidden node
+        // so the first preview/commit already reflects the chosen side.
         useScene.getState().updateNode(movingWindowNode.id, {
           side: sideOverride,
           rotation: [0, sideOverride === 'back' ? Math.PI : 0, 0],
@@ -733,6 +870,16 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
       }
     }
 
+    // Shift toggles force-place — re-run the on-wall preview so the tint flips
+    // green↔red live (pointer stationary). Commit gates still read shift fresh.
+    const onShiftToggle = (e: KeyboardEvent) => {
+      if (e.key !== 'Shift') return
+      const held = e.type === 'keydown'
+      if (held === shiftHeld) return
+      shiftHeld = held
+      if (!committed && lastTarget) applyPreview(lastTarget)
+    }
+
     emitter.on('wall:enter', onWallEnter)
     emitter.on('wall:move', onWallMove)
     emitter.on('wall:click', onWallClick)
@@ -745,6 +892,8 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
     emitter.on('tool:cancel', onCancel)
     window.addEventListener('pointerup', onPlacementDragPointerUp)
     window.addEventListener('keydown', onKeyDown)
+    window.addEventListener('keydown', onShiftToggle)
+    window.addEventListener('keyup', onShiftToggle)
 
     return () => {
       // Safety cleanup: if still transient on unmount (e.g. phase switch mid-move)
@@ -766,9 +915,15 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
             roofSegmentId: original.roofSegmentId,
             roofFace: original.roofFace,
             metadata: original.metadata,
+            visible: original.visible,
           })
           if (original.parentId) markHostDirty(original.parentId)
         }
+      } else if (current && current.visible === false) {
+        // Safety net: a fresh (isNew) clone isn't marked `isTransient`; if we
+        // unmount mid-free-follow it would be left hidden. Reveal it so it never
+        // becomes an invisible orphan (place-preset deletes a true cancel).
+        useScene.getState().updateNode(movingWindowNode.id, { visible: true })
       }
       useLiveTransforms.getState().clear(movingWindowNode.id)
       useAlignmentGuides.getState().clear()
@@ -786,6 +941,8 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
       emitter.off('tool:cancel', onCancel)
       window.removeEventListener('pointerup', onPlacementDragPointerUp)
       window.removeEventListener('keydown', onKeyDown)
+      window.removeEventListener('keydown', onShiftToggle)
+      window.removeEventListener('keyup', onShiftToggle)
     }
   }, [movingWindowNode, exitMoveMode])
 
@@ -802,9 +959,35 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
   useEffect(() => () => edgesGeo.dispose(), [edgesGeo])
 
   return (
-    <group ref={cursorGroupRef} visible={false}>
-      <lineSegments geometry={edgesGeo} layers={EDITOR_LAYER} material={edgeMaterial} />
-    </group>
+    <>
+      <group ref={cursorGroupRef} visible={false}>
+        <lineSegments geometry={edgesGeo} layers={EDITOR_LAYER} material={edgeMaterial} />
+      </group>
+      {/* Placement ghost shown for the whole move (the real pale node stays
+          hidden): red off-wall / colliding, green on a valid wall. */}
+      {ghostPose && (
+        <group position={ghostPose.position} rotation-y={ghostPose.rotationY}>
+          <WindowPreview
+            invalid={ghostPose.tint === 'invalid'}
+            node={ghostNode}
+            valid={ghostPose.tint === 'valid'}
+          />
+        </group>
+      )}
+      {/* Floor "shadow" projection: footprint + dashed drop-line, so an elevated
+          window's plan position is legible while placing. World-space, so it's a
+          sibling of the ghost group, not a child. */}
+      {ghostPose && (
+        <WindowFloorProjection
+          centerX={ghostPose.position[0]}
+          centerY={ghostPose.position[1]}
+          centerZ={ghostPose.position[2]}
+          floorY={ghostPose.floorY}
+          rotationY={ghostPose.rotationY}
+          width={movingWindowNode.width}
+        />
+      )}
+    </>
   )
 }
 

packages/nodes/src/window/preview.tsx

@@ -16,7 +16,15 @@ import type { WindowNode } from './schema'
  * The root mesh's layer is set to EDITOR_LAYER because the invisible hitbox
  * material on SCENE_LAYER would poison the WebGPU MRT pass (project gotcha).
  */
-const WindowPreview = ({ node, invalid }: { node: WindowNode; invalid?: boolean }) => {
+const WindowPreview = ({
+  node,
+  invalid,
+  valid,
+}: {
+  node: WindowNode
+  invalid?: boolean
+  valid?: boolean
+}) => {
   const mesh = useMemo(() => {
     const m = buildWindowPreviewMesh(node)
     m.layers.set(EDITOR_LAYER)
@@ -32,9 +40,9 @@ const WindowPreview = ({ node, invalid }: { node: WindowNode; invalid?: boolean
     node.sillThickness,
   ])
 
-  // Ghost treatment (clone + tint + raycast-off) re-applies if `invalid`
-  // flips; its cleanup only disposes the clones it made.
-  useEffect(() => applyGhost(mesh, { invalid }), [mesh, invalid])
+  // Ghost treatment (clone + tint + raycast-off) re-applies if the tint flips;
+  // its cleanup only disposes the clones it made.
+  useEffect(() => applyGhost(mesh, { invalid, valid }), [mesh, invalid, valid])
 
   // Geometry is freshly built per `mesh` and owned here — dispose it only
   // when the mesh itself is replaced/unmounted, never on an `invalid` toggle.

packages/nodes/src/window/tool.tsx

@@ -39,8 +39,14 @@ import {
   worldToSelectedBuildingLocal,
 } from '../shared/roof-wall-opening-placement'
 import { resolveWallSlideAlignment } from '../shared/wall-opening-alignment'
+import { WindowFloorProjection } from './floor-projection'
 import WindowPreview from './preview'
-import { clampToWall, hasWallChildOverlap, wallLocalToWorld } from './window-math'
+import {
+  clampToWall,
+  DEFAULT_WINDOW_SILL_M,
+  hasWallChildOverlap,
+  wallLocalToWorld,
+} from './window-math'
 
 // Shared edge material — reuse across renders, just toggle color
 const edgeMaterial = new LineBasicNodeMaterial({
@@ -52,10 +58,12 @@ const edgeMaterial = new LineBasicNodeMaterial({
 
 const FALLBACK_WIDTH = 1.5
 const FALLBACK_HEIGHT = 1.5
-const FALLBACK_SILL_LIFT = 0.45
+// Off-wall ghost lift = the default sill, so the floating preview matches the
+// sill the floor-cursor placement commits at.
+const FALLBACK_SILL_LIFT = DEFAULT_WINDOW_SILL_M
 // Default sill centre for a window snapped from the floor (the floor cursor
-// carries no wall-face height). 0.9 m sill + half the 1.5 m default height.
-const DEFAULT_SILL_CENTER_Y = 0.9 + FALLBACK_HEIGHT / 2
+// carries no wall-face height): the default sill + half the default height.
+const DEFAULT_SILL_CENTER_Y = DEFAULT_WINDOW_SILL_M + FALLBACK_HEIGHT / 2
 const roofFallbackPoint = new Vector3()
 
 // What currently owns the cursor frame: a wall/roof mesh hover, or null when
@@ -79,14 +87,24 @@ const WindowTool: React.FC = () => {
 
   // Off-host floating ghost: the real window geometry follows the cursor
   // over the grid (tinted invalid). Mutually exclusive with the on-host draft.
+  // `floorY` feeds the floor "shadow" projection; `side` carries the R-flip so
+  // the floating ghost faces the side that will be committed.
   const [fallbackPose, setFallbackPose] = useState<{
     position: [number, number, number]
     rotationY: number
+    floorY: number
+    side: WindowNode['side']
   } | null>(null)
 
+  // Ghost preview node — zeroed transform + the live facing side (rebuilds on R).
   const ghostStub = useMemo(
-    () => WindowNode.parse({ position: [0, 0, 0], rotation: [0, 0, 0] }),
-    [],
+    () =>
+      WindowNode.parse({
+        position: [0, 0, 0],
+        rotation: [0, 0, 0],
+        side: fallbackPose?.side ?? 'front',
+      }),
+    [fallbackPose?.side],
   )
 
   useEffect(() => {
@@ -104,6 +122,9 @@ const WindowTool: React.FC = () => {
     // to the last wall hover so the flip shows live before commit.
     let sideFlip = false
     let lastWallEvent: WallEvent | null = null
+    // Last open-floor cursor point (level-local X/Z) + floor Y, so an R-flip
+    // while free-following can re-render the floating ghost with the new facing.
+    let lastFloorPoint: { pos: [number, number, number]; floorY: number } | null = null
 
     const getLevelId = () => useViewer.getState().selection.levelId
     const getLevelYOffset = () => {
@@ -157,21 +178,34 @@ const WindowTool: React.FC = () => {
 
     // Off-host fallback: hide the wireframe outline and float the real window
     // geometry (tinted invalid) at the cursor so the armed tool is visible.
-    const showGhostAt = (position: [number, number, number]) => {
+    const showGhostAt = (position: [number, number, number], floorY: number) => {
       if (cursorGroupRef.current) cursorGroupRef.current.visible = false
-      setFallbackPose({ position, rotationY: 0 })
+      lastFloorPoint = { pos: position, floorY }
+      // `sideFlip` (R) flips the facing — back is a π yaw on the floating ghost.
+      setFallbackPose({
+        position,
+        rotationY: sideFlip ? Math.PI : 0,
+        floorY,
+        side: sideFlip ? 'back' : 'front',
+      })
       useAlignmentGuides.getState().clear()
       clearOpeningGuides3D()
     }
 
     const showRoofFallbackCursor = (event: RoofEvent) => {
       const [x, , z] = worldToSelectedBuildingLocal(roofFallbackPoint.set(...event.position))
-      showGhostAt([x, getLevelYOffset() + FALLBACK_HEIGHT / 2 + FALLBACK_SILL_LIFT, z])
+      showGhostAt(
+        [x, getLevelYOffset() + FALLBACK_HEIGHT / 2 + FALLBACK_SILL_LIFT, z],
+        getLevelYOffset(),
+      )
     }
 
     const showWallFallbackCursor = (event: WallEvent) => {
       const [x, , z] = worldToSelectedBuildingLocal(roofFallbackPoint.set(...event.position))
-      showGhostAt([x, getLevelYOffset() + FALLBACK_HEIGHT / 2 + FALLBACK_SILL_LIFT, z])
+      showGhostAt(
+        [x, getLevelYOffset() + FALLBACK_HEIGHT / 2 + FALLBACK_SILL_LIFT, z],
+        getLevelYOffset(),
+      )
     }
 
     // Sill alignment (snap + guide): a sibling sill/centre/top wins over the
@@ -211,13 +245,16 @@ const WindowTool: React.FC = () => {
       bypassSnap: boolean,
       ignoreId?: string,
     ) => {
+      // bypassSnap is set by Shift (see callers). Shift = free-place: land at the
+      // raw cursor but keep the along-wall guides visible. bypass (Alt) still
+      // hard-disables alignment.
       const localX = resolveWallSlideAlignment({
         wallNode: wall,
         rawLocalX,
         width,
         candidates: alignmentCandidates,
-        bypass,
-        bypassSnap,
+        bypass: bypass && !bypassSnap,
+        freePlace: bypassSnap,
       })
       const localY = resolvePlacementY({
         wall,
@@ -454,7 +491,8 @@ const WindowTool: React.FC = () => {
         bypassSnap,
         draftRef.current.id,
       )
-      if (!valid) return
+      // Shift force-places over a collision (the draft stays red as a warning).
+      if (!valid && !bypassSnap) return
 
       commitWindowAtWall(event.node, clampedX, clampedY, side, itemRotation)
       event.stopPropagation()
@@ -485,7 +523,7 @@ const WindowTool: React.FC = () => {
       lastWallEvent = null
       const [x, y, z] = event.localPosition
       destroyDraft()
-      showGhostAt([x, y + FALLBACK_HEIGHT / 2 + FALLBACK_SILL_LIFT, z])
+      showGhostAt([x, y + FALLBACK_HEIGHT / 2 + FALLBACK_SILL_LIFT, z], y)
     }
 
     // ── Roof-segment wall faces ─────────────────────────────────────
@@ -553,7 +591,9 @@ const WindowTool: React.FC = () => {
     const onRoofClick = (event: RoofEvent) => {
       if (!draftRef.current?.roofSegmentId) return
       const target = resolveRoofTarget(event)
-      if (!target?.valid) return
+      // Shift force-places over a colliding roof-face target (see onWallClick).
+      if (!target) return
+      if (!target.valid && event.nativeEvent?.shiftKey !== true) return
       const { segment, face, position } = target
 
       const draft = draftRef.current
@@ -617,19 +657,24 @@ const WindowTool: React.FC = () => {
       hostKind = null
     }
 
-    // R flips the window's facing side mid-placement (front ↔ back), like the
-    // committed-selected R flip. Only meaningful while snapped to a wall (the
-    // off-wall ghost has no orientation), so it acts only then — re-applying
-    // the last wall hover so the snapped preview flips live.
+    // R flips the window's facing side mid-placement (front ↔ back). ALWAYS
+    // toggles the persistent flip intent — never a no-op (the old `!lastWallEvent`
+    // guard dropped R off-wall / before the first hover). Then re-renders the
+    // current preview so the flip shows live and matches commit.
     const onKeyDown = (e: KeyboardEvent) => {
       if (e.key !== 'r' && e.key !== 'R') return
-      if (!lastWallEvent) return
+      if (e.repeat) return
       const t = e.target as HTMLElement | null
       if (t && (t.tagName === 'INPUT' || t.tagName === 'TEXTAREA' || t.isContentEditable)) return
       e.preventDefault()
       sideFlip = !sideFlip
       triggerSFX('sfx:item-rotate')
-      onWallHover(lastWallEvent)
+      if (lastWallEvent) {
+        onWallHover(lastWallEvent)
+      } else if (lastFloorPoint) {
+        showGhostAt(lastFloorPoint.pos, lastFloorPoint.floorY)
+      }
+      // else: no preview yet — `sideFlip` is set, so the first hover/follow uses it.
     }
 
     emitter.on('wall:enter', onWallHover)
@@ -690,6 +735,18 @@ const WindowTool: React.FC = () => {
           <WindowPreview invalid node={ghostStub} />
         </group>
       )}
+      {/* Floor "shadow" projection for the off-host ghost (drop-line + footprint)
+          so the elevated window's plan position is legible while placing. */}
+      {fallbackPose && (
+        <WindowFloorProjection
+          centerX={fallbackPose.position[0]}
+          centerY={fallbackPose.position[1]}
+          centerZ={fallbackPose.position[2]}
+          floorY={fallbackPose.floorY}
+          rotationY={fallbackPose.rotationY}
+          width={FALLBACK_WIDTH}
+        />
+      )}
     </>
   )
 }

packages/nodes/src/window/window-math.ts

@@ -1,12 +1,13 @@
-import {
-  type AnyNodeId,
-  type DoorNode,
-  getScaledDimensions,
-  type ItemNode,
-  useScene,
-  type WallNode,
-  type WindowNode,
-} from '@pascal-app/core'
+import type { WallNode } from '@pascal-app/core'
+
+/**
+ * Default sill height (metres from the floor to the BOTTOM of a window) for a
+ * fresh window that has no wall-face height yet — the off-wall ghost and the
+ * floor-cursor placement use it so a new window floats slightly above the
+ * ground rather than sitting on it. The committed Y is the window's CENTRE, so
+ * callers add `height / 2`. An existing window keeps its own sill.
+ */
+export const DEFAULT_WINDOW_SILL_M = 0.5
 
 /**
  * Converts wall-local (X along wall, Y = height above wall base) to world XYZ.
@@ -54,64 +55,8 @@ export function clampToWall(
 }
 
 /**
- * Directly checks the wall's children for bounding-box overlap with a proposed window.
- * Works for both `item` type (position[1] = bottom) and `window` type (position[1] = center).
- * The spatial grid only tracks `item` nodes, so windows must be checked this way.
- * Reads the wall's latest children from the store (not the event node) to avoid stale data.
+ * Wall-child overlap is shared by door + window placement (one source of
+ * truth in `shared/wall-attach-target.ts`). Re-exported here so existing
+ * `./window-math` importers don't change.
  */
-export function hasWallChildOverlap(
-  wallId: string,
-  clampedX: number,
-  clampedY: number,
-  width: number,
-  height: number,
-  ignoreId?: string,
-): boolean {
-  const nodes = useScene.getState().nodes
-  const wallNode = nodes[wallId as AnyNodeId] as WallNode | undefined
-  if (!wallNode) return true // Block if wall not found
-  const halfW = width / 2
-  const halfH = height / 2
-  const newBottom = clampedY - halfH
-  const newTop = clampedY + halfH
-  const newLeft = clampedX - halfW
-  const newRight = clampedX + halfW
-
-  for (const childId of Array.isArray(wallNode.children) ? wallNode.children : []) {
-    if (childId === ignoreId) continue
-    const child = nodes[childId as AnyNodeId]
-    if (!child) continue
-
-    let childLeft: number, childRight: number, childBottom: number, childTop: number
-
-    if (child.type === 'item') {
-      const item = child as ItemNode
-      if (item.asset.attachTo !== 'wall' && item.asset.attachTo !== 'wall-side') continue
-      const [w, h] = getScaledDimensions(item)
-      childLeft = item.position[0] - w / 2
-      childRight = item.position[0] + w / 2
-      childBottom = item.position[1] // items store bottom Y
-      childTop = item.position[1] + h
-    } else if (child.type === 'window') {
-      const win = child as WindowNode
-      childLeft = win.position[0] - win.width / 2
-      childRight = win.position[0] + win.width / 2
-      childBottom = win.position[1] - win.height / 2 // windows store center Y
-      childTop = win.position[1] + win.height / 2
-    } else if (child.type === 'door') {
-      const door = child as DoorNode
-      childLeft = door.position[0] - door.width / 2
-      childRight = door.position[0] + door.width / 2
-      childBottom = door.position[1] - door.height / 2 // doors store center Y
-      childTop = door.position[1] + door.height / 2
-    } else {
-      continue
-    }
-
-    const xOverlap = newLeft < childRight && newRight > childLeft
-    const yOverlap = newBottom < childTop && newTop > childBottom
-    if (xOverlap && yOverlap) return true
-  }
-
-  return false
-}
+export { hasWallChildOverlap } from '../shared/wall-attach-target'

wiki/architecture/README.md

@@ -12,7 +12,7 @@ Canonical rules for code that touches `packages/core`, `packages/viewer`, `packa
 | [node-definitions](node-definitions.md) | Three-checkbox composition model for registry-driven kinds (`geometry` / `renderer` / `system`) |
 | [materials-and-themes](materials-and-themes.md) | Surface colour: surface roles, colour presets, the textures axis, and scene themes (appearance / ground / clay tints) |
 | [plugin-authoring](plugin-authoring.md) | Public contract for external plugins — `Plugin` shape, `setPluginDiscovery`, lifecycle, what's in and out of v1 |
-| [tools](tools.md) | Editor tools structure, manipulation constraints, and Shift bypass defaults |
+| [tools](tools.md) | Editor tools structure, 2D↔3D behavioral parity, manipulation constraints, and Shift bypass defaults |
 | [viewer-isolation](viewer-isolation.md) | Keeping `@pascal-app/viewer` editor-agnostic |
 | [selection-managers](selection-managers.md) | Two-layer selection (viewer + editor), events, outliner |
 | [scene-registry](scene-registry.md) | Global node ID → Object3D map and `useRegistry` |

wiki/architecture/tools.md

@@ -99,6 +99,18 @@ export function MyTool() {
 3. Add the tool identifier to the `useEditor` tool union type.
 4. If the tool requires new node types, add schema + renderer + system first.
 
+## 2D ↔ 3D behavioral parity (default expectation)
+
+The 2D floor-plan view and the 3D view are two presentations of the **same** edit. Whenever a behavior is applicable to both, it must exist in both — the *mechanism* may differ (a 3D raycast hover vs a plan-space nearest-wall query; a real mesh ghost vs an SVG symbol), but the *felt behavior* should match. When you add or change an interaction in one view, port it to the other in the same change, or write down why it genuinely doesn't apply.
+
+Concretely, door/window placement/move keeps these in lockstep across `{door,window}/move-tool.tsx` (3D) and `{door,window}/floorplan-move.ts` (2D):
+
+- **Snap target**: nearest wall to the true cursor (shared `findClosestWallInPlan` / wall raycast), free-follow off-wall, commit only on a host.
+- **Move SFX**: a soft `sfx:grid-snap` click per grid step while sliding (free-follow plan XZ or on-wall along-X, quantized + deduped so it isn't a machine-gun) and a soft `sfx:item-pick` cue on the floor→wall snap. Both tools carry an identical `tickGridStep` / `tickWallSnap` pair — keep them in sync.
+- **R-flip** facing mid-placement, **Shift** to free snap/alignment (guides stay visible) and force-place over collisions, faithful ghost/symbol, deterministic single-undo commit.
+
+Tells that you've broken parity: a sound/guide/snap that fires in 3D but is silent in 2D (or vice-versa), or a fix landed in one move file but not its sibling. The two move files are deliberately near-mirrors; diff them when in doubt.
+
 ## Move coexistence: 2D `FloorplanRegistryMoveOverlay` + legacy 3D mover
 
 While a kind is mid-migration its move can run through two paths at once: the registry-driven 2D `FloorplanRegistryMoveOverlay` (`def.floorplanMoveTarget`) and the legacy 3D mover (e.g. `MoveItemContent`). Both react to `setMovingNode(node)`, both mount, both want to commit. Two pitfalls surfaced and have stable fixes; replicate the patterns when porting another kind to coexist.