Merge origin/main (#407 placement restructure) into opening-proximity-guides

#407 ("Always-visible placement ghosts + true-nearest 2D opening snap") restructured the door/window placement tools: it split the old create-in-resolve into a pure resolveWallPlacement() + side-effecting applyWallTarget(), added an off-host floating ghost (fallbackPose / showGhostAt), unified wall hover into onWallHover, and extracted commit{Door,Window}AtWall. Conflict resolution (door/tool.tsx, window/tool.tsx): - Re-homed the single publishOpeningGuidesForWallEvent() call into applyWallTarget (after the draft update + updateCursor), using that scope (wall, getSlabElevationForWall(wall)); door includeVertical:false, window true. - Routed clearOpeningGuides3D() through showGhostAt so every off-host fallback path clears; kept clears in hideCursor, commit helpers, onRoofHover, teardown. - Made the window sill snap (resolvePlacementY) event-free and call it from the pure resolveWallPlacement, so hover + click both get sill/centre/top snapping; Shift bypasses, the moving draft is excluded via ignoreId. - Dropped the branch's inline onWallClick in favour of #407's onWallClick + commitWindowAtWall (no behavior lost). - Reconstructed both files' import blocks, which the auto-merge had truncated to stubs (only tsc caught it). All other conflicts auto-merged (registry types, floorplan-registry-layer, both move-tools). Verified: typecheck 9/9, biome clean, nodes 169 + core 594 tests pass, editor `bun run build` 7/7. Merge resolution reviewed by Codex (adversarial): no semantic regressions; all #407 behavior preserved. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2026-06-15 12:58:00 -04:00
parent 69aa272004 1628b728fa
commit c9121d322c
59 changed files with 2212 additions and 807 deletions
@@ -2,16 +2,15 @@ import {
  type AnyNodeId,
  type FloorplanMoveTarget,
  type FloorplanMoveTargetSession,
+  useLiveTransforms,
  useScene,
  type WallNode,
+  WallNode as WallNodeSchema,
  type WindowNode,
 } from '@pascal-app/core'
-import { snapToHalf } from '@pascal-app/editor'
+import { snapToHalf, usePlacementPreview } from '@pascal-app/editor'
 import { createFloorplanCursorResolver } from '../shared/floorplan-cursor'
-import {
-  getRoofHostedOpeningLevelId,
-  getRoofHostedOpeningPlanPoint,
-} from '../shared/roof-opening-host'
+import { getOpeningHostLevelId, getRoofHostedOpeningPlanPoint } from '../shared/roof-opening-host'
 import {
  findClosestWallInPlan,
  projectWallLocalPointToPlan,
@@ -32,15 +31,9 @@ import { clampToWall, hasWallChildOverlap } from './window-math'
 */

 export const windowFloorplanMoveTarget: FloorplanMoveTarget<WindowNode> = ({ node }) => {
-  const startLevelId = (() => {
-    // Wall-hosted: the wall's parent is the level. Roof-hosted: walk
-    // segment → roof → level.
-    const nodes = useScene.getState().nodes
-    const roofLevelId = getRoofHostedOpeningLevelId(node, nodes)
-    if (roofLevelId) return roofLevelId
-    const wall = nodes[node.parentId as AnyNodeId]
-    return wall ? (wall.parentId as AnyNodeId | null) : null
-  })()
+  // The level that owns the wall-snap candidates — resolves the wall-hosted,
+  // roof-hosted, and fresh-placement parentings (see `getOpeningHostLevelId`).
+  const startLevelId = getOpeningHostLevelId(node, useScene.getState().nodes)
  const originalWall = node.parentId
    ? (useScene.getState().nodes[node.parentId as AnyNodeId] as WallNode | undefined)
    : undefined
@@ -50,12 +43,21 @@ export const windowFloorplanMoveTarget: FloorplanMoveTarget<WindowNode> = ({ nod
        ? projectWallLocalPointToPlan(originalWall, node.position[0])
        : (getRoofHostedOpeningPlanPoint(node, useScene.getState().nodes) ?? [node.position[0], 0]),
    metadata: node.metadata,
+    // Absolute: query the wall snap with the TRUE cursor (see the matching
+    // comment in `doorFloorplanMoveTarget`). Relative mode anchored the search
+    // to the original wall, which let the window snap to a farther wall across
+    // a thin gap instead of the one under the cursor.
+    mode: 'absolute',
  })

  // Preserve the source window's local Y — 2D move doesn't have a way
  // to express vertical motion, so we keep whatever vertical position
-  // the window had when the move started.
-  const startLocalY = node.position[1]
+  // the window had when the move started. A fresh preset/catalog clone is
+  // 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

  // Track the last successful placement so `commit()` can write it
  // atomically — same deterministic-commit fix as `doorFloorplanMoveTarget`.
@@ -69,13 +71,72 @@ export const windowFloorplanMoveTarget: FloorplanMoveTarget<WindowNode> = ({ nod
    roofFace: undefined
  } | null = null

+  // R flips the window's facing (front ↔ back) mid-placement — see
+  // `doorFloorplanMoveTarget`. `apply` re-derives the side each move, so the
+  // flip is a persistent XOR plus a π rotation offset.
+  let flipped = false
+  let lastApply: {
+    planPoint: readonly [number, number]
+    modifiers: { shiftKey: boolean; altKey: boolean; ctrlKey: boolean; metaKey: boolean }
+  } | null = null
+  // 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
+
+  const freeFollow = (planPoint: readonly [number, number]) => {
+    onWall = false
+    lastValid = null
+    if ((useScene.getState().nodes[node.id as AnyNodeId] as WindowNode | undefined)?.visible) {
+      useScene.getState().updateNode(node.id as AnyNodeId, { visible: false })
+    }
+    const half = node.width / 2 + 0.5
+    const wall = WallNodeSchema.parse({
+      start: [planPoint[0] - half, planPoint[1]],
+      end: [planPoint[0] + half, planPoint[1]],
+      thickness: 0.1,
+    })
+    const ghost = {
+      ...node,
+      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],
+      visible: true,
+    } as WindowNode
+    usePlacementPreview.getState().set(ghost, wall)
+  }
+
  const session: FloorplanMoveTargetSession = {
    affectedIds: [node.id as AnyNodeId],
+    flipSide() {
+      flipped = !flipped
+      if (lastApply) this.apply(lastApply)
+    },
    apply({ planPoint, modifiers }) {
+      lastApply = { planPoint, modifiers }
+      // 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
+      // `useLiveTransforms` over the scene node for door/window), so the 2D
+      // slide — which writes the scene node — wouldn't show. Guarded on
+      // existence: `clear` allocates a new Map + re-renders.
+      if (useLiveTransforms.getState().transforms.has(node.id as AnyNodeId)) {
+        useLiveTransforms.getState().clear(node.id as AnyNodeId)
+      }
      const nodes = useScene.getState().nodes
      const resolvedPlanPoint = resolveCursor(planPoint)
      const hit = findClosestWallInPlan(resolvedPlanPoint, nodes, startLevelId)
-      if (!hit) return
+      if (!hit) {
+        freeFollow(resolvedPlanPoint)
+        return
+      }
+      onWall = true
+      usePlacementPreview.getState().clear()
+      if ((nodes[node.id as AnyNodeId] as WindowNode | undefined)?.visible === false) {
+        useScene.getState().updateNode(node.id as AnyNodeId, { visible: true })
+      }

      // Figma-style along-wall alignment first (edge-to-edge with other
      // openings / wall ends), winning over the 0.5m grid snap; falls back
@@ -99,10 +160,17 @@ export const windowFloorplanMoveTarget: FloorplanMoveTarget<WindowNode> = ({ nod
        node.height,
      )

+      const side: WindowNode['side'] = flipped
+        ? hit.side === 'front'
+          ? 'back'
+          : 'front'
+        : hit.side
+      const itemRotation = hit.itemRotation + (flipped ? Math.PI : 0)
+
      lastValid = {
        position: [clampedX, clampedY, 0],
-        rotation: [0, hit.itemRotation, 0],
-        side: hit.side,
+        rotation: [0, itemRotation, 0],
+        side,
        parentId: hit.wall.id,
        wallId: hit.wall.id,
        // Re-anchoring to a wall ends any roof-segment hosting; the
@@ -119,6 +187,9 @@ export const windowFloorplanMoveTarget: FloorplanMoveTarget<WindowNode> = ({ nod
      ])
    },
    canCommit() {
+      // Off-wall the window is free-following — not placeable; the overlay
+      // reverts to the pre-move snapshot. Matches the 3D move.
+      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(
@@ -2,6 +2,7 @@ import {
  type AnyNodeId,
  collectAlignmentAnchors,
  emitter,
+  type GridEvent,
  isCurvedWall,
  type RoofEvent,
  type RoofNode,
@@ -106,6 +107,15 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode

    let currentHostId: string | null = movingWindowNode.parentId
    let committed = false
+    // Off-wall free-follow: over empty floor the window is parented to the
+    // level and tracks the cursor like an item. `freeFollowing` marks that
+    // state; `lastMeshEventTime` defers the floor handler whenever a wall/roof
+    // mesh event owns the same pointermove — that's the only thing that snaps.
+    let freeFollowing = false
+    let lastMeshEventTime = -1
+    // 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
    let dragAnchor: {
      wallId: string
      rawX: number
@@ -146,6 +156,17 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
      const id = getLevelId()
      return id ? (sceneRegistry.nodes.get(id as AnyNodeId)?.position.y ?? 0) : 0
    }
+
+    // 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
+    const getSillCenterY = () => {
+      const y = movingWindowNode.position[1]
+      return y > 0.1 ? y : DEFAULT_SILL + movingWindowNode.height / 2
+    }
    const getSlabElevation = (wallEvent: WallEvent) =>
      spatialGridManager.getSlabElevationForWall(
        wallEvent.node.parentId ?? '',
@@ -189,9 +210,12 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
      // Only interact with walls on the current level
      if (event.node.parentId !== getLevelId()) return

-      const side = getSideFromNormal(event.normal)
-      const itemRotation = calculateItemRotation(event.normal)
-      const cursorRotation = calculateCursorRotation(event.normal, event.node.start, event.node.end)
+      const faceSide = getSideFromNormal(event.normal)
+      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]
@@ -318,11 +342,13 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
    }

    const onWallEnter = (event: WallEvent) => {
+      lastMeshEventTime = event.nativeEvent?.timeStamp ?? -1
      const target = resolveMoveTarget(event)
      if (!target) {
        onWallLeave()
        return
      }
+      freeFollowing = false
      lastTarget = target
      lastRoofEvent = null
      applyPreview(target)
@@ -330,6 +356,7 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
    }

    const onWallMove = (event: WallEvent) => {
+      lastMeshEventTime = event.nativeEvent?.timeStamp ?? -1
      if (!isValidWallSideFace(event.normal)) {
        onWallLeave()
        return
@@ -349,21 +376,17 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
        onWallLeave()
        return
      }
+      freeFollowing = false
      lastTarget = target
      lastRoofEvent = null
      applyPreview(target)
      event.stopPropagation()
    }

-    const onWallClick = (event: WallEvent) => {
+    // Promote the moving window into its committed wall placement. Shared by
+    // the direct wall-mesh click and the floor proximity click.
+    const commitToWall = (target: NonNullable<typeof lastTarget>) => {
      if (committed) return
-      if (!isValidWallSideFace(event.normal)) return
-      if (isCurvedWall(event.node)) return
-      // Only interact with walls on the current level
-      if (event.node.parentId !== getLevelId()) return
-
-      const target = lastTarget?.wallId === event.node.id ? lastTarget : resolveMoveTarget(event)
-      if (!target?.valid) return
      committed = true

      let placedId: string
@@ -429,31 +452,78 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
      hideCursor()
      useViewer.getState().setSelection({ selectedIds: [placedId] })
      exitMoveMode()
+    }
+
+    const onWallClick = (event: WallEvent) => {
+      if (committed) return
+      if (!isValidWallSideFace(event.normal)) return
+      if (isCurvedWall(event.node)) return
+      // Only interact with walls on the current level
+      if (event.node.parentId !== getLevelId()) return
+
+      const target = lastTarget?.wallId === event.node.id ? lastTarget : resolveMoveTarget(event)
+      if (!target?.valid) return
+      commitToWall(target)
      event.stopPropagation()
    }

    const onWallLeave = () => {
+      // The cursor left the wall mesh. Don't snap back to the origin/original
+      // here — the floor proximity handler (onGridMove) takes over on the same
+      // pointermove: it snaps to a nearby wall or free-follows the cursor, so
+      // the window never blinks back to the building origin between a wall and
+      // open floor. Revert is left to free-follow / cancel / commit.
      hideCursor()
      useLiveTransforms.getState().clear(movingWindowNode.id)
      dragAnchor = null
      lastTarget = null
      lastRoofEvent = null
-      if (isNew) return // No original to restore for duplicates
-      // Move mode: restore to original position while off-wall
-      if (currentHostId && currentHostId !== original.parentId) {
-        markHostDirty(currentHostId)
+    }
+
+    // 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) => {
+      freeFollowing = true
+      lastTarget = null
+      lastRoofEvent = null
+      hideCursor()
+      useLiveTransforms.getState().clear(movingWindowNode.id)
+      const levelId = getLevelId()
+      const sillCenterY = getSillCenterY()
+      // Keep the R-flip visible while free-following (back = rotated π).
+      const yaw = sideOverride === 'back' ? Math.PI : 0
+      if (currentHostId !== levelId) {
+        if (currentHostId && currentHostId !== levelId) markHostDirty(currentHostId)
+        useScene.getState().updateNode(movingWindowNode.id, {
+          position: [localX, sillCenterY, localZ],
+          rotation: [0, yaw, 0],
+          side: sideOverride,
+          parentId: levelId ?? undefined,
+          wallId: undefined,
+          roofSegmentId: undefined,
+          roofFace: undefined,
+        })
+        currentHostId = levelId
+      } else {
+        useScene.getState().updateNode(movingWindowNode.id, {
+          position: [localX, sillCenterY, localZ],
+          rotation: [0, yaw, 0],
+          side: sideOverride,
+        })
      }
-      currentHostId = original.parentId
-      useScene.getState().updateNode(movingWindowNode.id, {
-        position: original.position,
-        rotation: original.rotation,
-        side: original.side,
-        parentId: original.parentId,
-        wallId: original.wallId,
-        roofSegmentId: original.roofSegmentId,
-        roofFace: original.roofFace,
-      })
-      if (original.parentId) markHostDirty(original.parentId)
+    }
+
+    const onGridMove = (event: GridEvent) => {
+      if (committed) return
+      if (useViewer.getState().cameraDragging) return
+      // A wall/roof mesh handler owns this exact pointermove (shared DOM
+      // timeStamp): the cursor ray is on a wall/roof, so it snaps. Otherwise
+      // the cursor is over open floor — free-follow it. No proximity magnet:
+      // 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)
    }

    // ── Roof-segment wall faces ─────────────────────────────────────
@@ -480,12 +550,14 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
    }

    const onRoofHover = (event: RoofEvent) => {
+      lastMeshEventTime = event.nativeEvent?.timeStamp ?? -1
      const target = resolveRoofMoveTarget(event)
      if (!target) {
        onRoofLeave()
        return
      }
      // Wall-frame drag anchor / live transform don't apply on a roof face.
+      freeFollowing = false
      dragAnchor = null
      lastTarget = null
      lastRoofEvent = event
@@ -586,26 +658,13 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
    }

    const onRoofLeave = () => {
+      // Mirror onWallLeave: don't revert to origin here — onGridMove takes
+      // over on the same pointermove (snap to a nearby wall or free-follow).
      hideCursor()
      useLiveTransforms.getState().clear(movingWindowNode.id)
      dragAnchor = null
      lastTarget = null
      lastRoofEvent = null
-      if (isNew) return
-      if (currentHostId && currentHostId !== original.parentId) {
-        markHostDirty(currentHostId)
-      }
-      currentHostId = original.parentId
-      useScene.getState().updateNode(movingWindowNode.id, {
-        position: original.position,
-        rotation: original.rotation,
-        side: original.side,
-        parentId: original.parentId,
-        wallId: original.wallId,
-        roofSegmentId: original.roofSegmentId,
-        roofFace: original.roofFace,
-      })
-      if (original.parentId) markHostDirty(original.parentId)
    }

    const onCancel = () => {
@@ -633,13 +692,47 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode

    const onPlacementDragPointerUp = (event: PointerEvent) => {
      if (!consumePlacementDragRelease(event)) return
-      if (lastTarget) {
-        onWallClick(lastTarget.event)
+      // 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) {
+        commitToWall(lastTarget)
        return
      }
      if (lastRoofEvent) onRoofClick(lastRoofEvent)
    }

+    // R flips the window's facing side mid-placement (front ↔ back), like the
+    // committed-selected R flip — usable before commit, whether snapped to a
+    // wall or free-following. No-op on a roof-segment face (front-only host).
+    const onKeyDown = (e: KeyboardEvent) => {
+      if (committed) return
+      if (e.key !== 'r' && e.key !== 'R') return
+      const target = e.target as HTMLElement | null
+      if (
+        target &&
+        (target.tagName === 'INPUT' || target.tagName === 'TEXTAREA' || target.isContentEditable)
+      ) {
+        return
+      }
+      const onWall = lastTarget !== null
+      if (!(onWall || freeFollowing)) return
+      e.preventDefault()
+      sideOverride = sideOverride === 'front' ? 'back' : 'front'
+      triggerSFX('sfx:item-rotate')
+      if (onWall) {
+        const next = resolveMoveTarget(lastTarget!.event)
+        if (next) {
+          lastTarget = next
+          applyPreview(next)
+        }
+      } else {
+        useScene.getState().updateNode(movingWindowNode.id, {
+          side: sideOverride,
+          rotation: [0, sideOverride === 'back' ? Math.PI : 0, 0],
+        })
+      }
+    }
+
    emitter.on('wall:enter', onWallEnter)
    emitter.on('wall:move', onWallMove)
    emitter.on('wall:click', onWallClick)
@@ -648,8 +741,10 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
    emitter.on('roof:move', onRoofHover)
    emitter.on('roof:click', onRoofClick)
    emitter.on('roof:leave', onRoofLeave)
+    emitter.on('grid:move', onGridMove)
    emitter.on('tool:cancel', onCancel)
    window.addEventListener('pointerup', onPlacementDragPointerUp)
+    window.addEventListener('keydown', onKeyDown)

    return () => {
      // Safety cleanup: if still transient on unmount (e.g. phase switch mid-move)
@@ -687,8 +782,10 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
      emitter.off('roof:move', onRoofHover)
      emitter.off('roof:click', onRoofClick)
      emitter.off('roof:leave', onRoofLeave)
+      emitter.off('grid:move', onGridMove)
      emitter.off('tool:cancel', onCancel)
      window.removeEventListener('pointerup', onPlacementDragPointerUp)
+      window.removeEventListener('keydown', onKeyDown)
    }
  }, [movingWindowNode, exitMoveMode])

@@ -0,0 +1,54 @@
+'use client'
+
+import { EDITOR_LAYER } from '@pascal-app/editor'
+import { buildWindowPreviewMesh } from '@pascal-app/viewer'
+import { useEffect, useMemo } from 'react'
+import { applyGhost } from '../shared/ghost-materials'
+import type { WindowNode } from './schema'
+
+/**
+ * Translucent preview of a window — used by the placement tool's floating ghost.
+ *
+ * Builds the window mesh via buildWindowPreviewMesh (so the preview shape stays in
+ * lockstep with committed windows), then applies ghost treatment (translucent,
+ * raycast-off, tinted red if invalid).
+ *
+ * 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 mesh = useMemo(() => {
+    const m = buildWindowPreviewMesh(node)
+    m.layers.set(EDITOR_LAYER)
+    return m
+  }, [
+    node.width,
+    node.height,
+    node.frameDepth,
+    node.openingShape,
+    node.windowType,
+    node.sill,
+    node.sillDepth,
+    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])
+
+  // Geometry is freshly built per `mesh` and owned here — dispose it only
+  // when the mesh itself is replaced/unmounted, never on an `invalid` toggle.
+  useEffect(
+    () => () => {
+      mesh.traverse((obj) => {
+        const m = obj as { geometry?: { dispose: () => void } }
+        m.geometry?.dispose()
+      })
+    },
+    [mesh],
+  )
+
+  return <primitive object={mesh} />
+}
+
+export default WindowPreview
@@ -10,6 +10,7 @@ import {
  spatialGridManager,
  useScene,
  type WallEvent,
+  type WallNode,
  WindowNode,
 } from '@pascal-app/core'
 import {
@@ -23,7 +24,7 @@ import {
  useAlignmentGuides,
 } from '@pascal-app/editor'
 import { useViewer } from '@pascal-app/viewer'
-import { useEffect, useMemo, useRef } from 'react'
+import { useEffect, useMemo, useRef, useState } from 'react'
 import { BoxGeometry, EdgesGeometry, type Group, type LineSegments, Vector3 } from 'three'
 import { LineBasicNodeMaterial } from 'three/webgpu'
 import {
@@ -38,6 +39,7 @@ import {
  worldToSelectedBuildingLocal,
 } from '../shared/roof-wall-opening-placement'
 import { resolveWallSlideAlignment } from '../shared/wall-opening-alignment'
+import WindowPreview from './preview'
 import { clampToWall, hasWallChildOverlap, wallLocalToWorld } from './window-math'

 // Shared edge material — reuse across renders, just toggle color
@@ -51,33 +53,65 @@ const edgeMaterial = new LineBasicNodeMaterial({
 const FALLBACK_WIDTH = 1.5
 const FALLBACK_HEIGHT = 1.5
 const FALLBACK_SILL_LIFT = 0.45
+// 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
 const roofFallbackPoint = new Vector3()

+// What currently owns the cursor frame: a wall/roof mesh hover, or null when
+// the cursor is over open floor (the grid handler then free-follows).
+type HostKind = 'wall' | 'roof' | null
+
 /**
 * Window tool — places WindowNodes on walls and on roof-segment wall
 * faces (the generated base walls under a roof, including coplanar gable
 * ends — a window can sit in the gable pediment).
- * Shows a rectangle cursor (green = valid, red = invalid) matching window dimensions.
+ *
+ * The ghost follows the cursor everywhere (like moving an item): over open
+ * floor it floats as an invalid (unplaceable) ghost; the moment the cursor ray
+ * hovers a wall (or roof-segment face) the real draft snaps onto it. Snapping
+ * engages only on an actual mesh hover — no proximity magnet.
 */
 const WindowTool: React.FC = () => {
  const draftRef = useRef<WindowNode | null>(null)
  const cursorGroupRef = useRef<Group>(null!)
  const edgesRef = useRef<LineSegments>(null!)

+  // Off-host floating ghost: the real window geometry follows the cursor
+  // over the grid (tinted invalid). Mutually exclusive with the on-host draft.
+  const [fallbackPose, setFallbackPose] = useState<{
+    position: [number, number, number]
+    rotationY: number
+  } | null>(null)
+
+  const ghostStub = useMemo(
+    () => WindowNode.parse({ position: [0, 0, 0], rotation: [0, 0, 0] }),
+    [],
+  )
+
  useEffect(() => {
    useScene.temporal.getState().pause()

+    let hostKind: HostKind = null
+    // timeStamp of the most recent wall/roof mesh event. A wall/roof hover and
+    // the grid raycast from the SAME pointermove share the source DOM event's
+    // timeStamp, so the grid handler can detect "a mesh handler already owns
+    // this frame" without depending on event order or on a leave firing (node
+    // events are suppressed during a camera drag, so a sticky boolean would
+    // strand the draft after an orbit; a per-frame timestamp self-heals).
+    let lastMeshEventTime = -1
+    // R flips the window's facing side mid-placement (front ↔ back); re-applied
+    // to the last wall hover so the flip shows live before commit.
+    let sideFlip = false
+    let lastWallEvent: WallEvent | null = null
+
    const getLevelId = () => useViewer.getState().selection.levelId
    const getLevelYOffset = () => {
      const id = getLevelId()
      return id ? (sceneRegistry.nodes.get(id as AnyNodeId)?.position.y ?? 0) : 0
    }
-    const getSlabElevation = (wallEvent: WallEvent) =>
-      spatialGridManager.getSlabElevationForWall(
-        wallEvent.node.parentId ?? '',
-        wallEvent.node.start,
-        wallEvent.node.end,
-      )
+    const getSlabElevationForWall = (wall: WallNode) =>
+      spatialGridManager.getSlabElevationForWall(wall.parentId ?? '', wall.start, wall.end)

    const markHostDirty = (hostId: string) => {
      useScene.getState().dirtyNodes.add(hostId as AnyNodeId)
@@ -96,6 +130,7 @@ const WindowTool: React.FC = () => {
      if (cursorGroupRef.current) cursorGroupRef.current.visible = false
      useAlignmentGuides.getState().clear()
      clearOpeningGuides3D()
+      setFallbackPose(null)
    }

    // Alignment candidates — anchors of every alignable object; refreshed
@@ -103,11 +138,15 @@ const WindowTool: React.FC = () => {
    // (along-wall only; the floor-plane guides don't cover sill height).
    let alignmentCandidates = collectAlignmentAnchors(useScene.getState().nodes, '')

+    // On-host cursor: the green/red wireframe outline tracks a live draft.
+    // Showing it always clears the off-host floating ghost (they never
+    // coexist — a draft means the cursor is on a valid host).
    const updateCursor = (
      worldPosition: [number, number, number],
      cursorRotationY: number,
      valid: boolean,
    ) => {
+      setFallbackPose(null)
      const group = cursorGroupRef.current
      if (!group) return
      group.visible = true
@@ -116,26 +155,23 @@ const WindowTool: React.FC = () => {
      edgeMaterial.color.setHex(valid ? 0x22_c5_5e : 0xef_44_44)
    }

-    const showFallbackCursor = (event: GridEvent) => {
-      if (draftRef.current) return
-      const [x, y, z] = event.localPosition
-      updateCursor([x, y + FALLBACK_HEIGHT / 2 + FALLBACK_SILL_LIFT, z], 0, false)
+    // 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]) => {
+      if (cursorGroupRef.current) cursorGroupRef.current.visible = false
+      setFallbackPose({ position, rotationY: 0 })
      useAlignmentGuides.getState().clear()
      clearOpeningGuides3D()
    }

    const showRoofFallbackCursor = (event: RoofEvent) => {
      const [x, , z] = worldToSelectedBuildingLocal(roofFallbackPoint.set(...event.position))
-      updateCursor([x, getLevelYOffset() + FALLBACK_HEIGHT / 2 + FALLBACK_SILL_LIFT, z], 0, false)
-      useAlignmentGuides.getState().clear()
-      clearOpeningGuides3D()
+      showGhostAt([x, getLevelYOffset() + FALLBACK_HEIGHT / 2 + FALLBACK_SILL_LIFT, z])
    }

    const showWallFallbackCursor = (event: WallEvent) => {
      const [x, , z] = worldToSelectedBuildingLocal(roofFallbackPoint.set(...event.position))
-      updateCursor([x, getLevelYOffset() + FALLBACK_HEIGHT / 2 + FALLBACK_SILL_LIFT, z], 0, false)
-      useAlignmentGuides.getState().clear()
-      clearOpeningGuides3D()
+      showGhostAt([x, getLevelYOffset() + FALLBACK_HEIGHT / 2 + FALLBACK_SILL_LIFT, z])
    }

    // Sill alignment (snap + guide): a sibling sill/centre/top wins over the
@@ -143,226 +179,146 @@ const WindowTool: React.FC = () => {
    // draft's id once it exists (so it's excluded from the sibling scan), or ''
    // before the draft is created (nothing to exclude yet).
    const resolvePlacementY = (args: {
-      event: WallEvent
+      wall: WallNode
      movingId: string
      localX: number
+      rawLocalY: number
      width: number
      height: number
+      bypassSnap: boolean
    }): number => {
-      const rawY = args.event.localPosition[1]
-      if (args.event.nativeEvent?.shiftKey === true) return rawY
+      if (args.bypassSnap) return args.rawLocalY
      const sillY = resolveSillSnap({
-        wall: args.event.node,
+        wall: args.wall,
        movingId: args.movingId,
        localX: args.localX,
-        localY: rawY,
+        localY: args.rawLocalY,
        width: args.width,
        height: args.height,
        nodes: useScene.getState().nodes,
      })
-      return sillY ?? snapToHalf(rawY)
+      return sillY ?? snapToHalf(args.rawLocalY)
    }

-    const onWallEnter = (event: WallEvent) => {
-      if (!isValidWallSideFace(event.normal)) {
-        destroyDraft()
-        showWallFallbackCursor(event)
-        return
-      }
-      if (isCurvedWall(event.node)) {
-        destroyDraft()
-        showWallFallbackCursor(event)
-        return
-      }
-      const levelId = getLevelId()
-      if (!levelId) {
-        destroyDraft()
-        showWallFallbackCursor(event)
-        return
-      }
-      // Only interact with walls on the current level
-      if (event.node.parentId !== levelId) {
-        destroyDraft()
-        showWallFallbackCursor(event)
-        return
-      }
-
-      destroyDraft()
-
-      const side = getSideFromNormal(event.normal)
-      const itemRotation = calculateItemRotation(event.normal)
-      const cursorRotation = calculateCursorRotation(event.normal, event.node.start, event.node.end)
-
-      const width = 1.5
-      const height = 1.5
+    // Settle a wall target: alignment snap → sill clamp → overlap check.
+    const resolveWallPlacement = (
+      wall: WallNode,
+      rawLocalX: number,
+      rawLocalY: number,
+      width: number,
+      height: number,
+      bypass: boolean,
+      bypassSnap: boolean,
+      ignoreId?: string,
+    ) => {
      const localX = resolveWallSlideAlignment({
-        wallNode: event.node,
-        rawLocalX: event.localPosition[0],
+        wallNode: wall,
+        rawLocalX,
        width,
        candidates: alignmentCandidates,
-        bypass: event.nativeEvent?.altKey === true || event.nativeEvent?.shiftKey === true,
-        bypassSnap: event.nativeEvent?.shiftKey === true,
-      })
-      const localY = resolvePlacementY({ event, movingId: '', localX, width, height })
-
-      const { clampedX, clampedY } = clampToWall(event.node, localX, localY, width, height)
-
-      const node = WindowNode.parse({
-        position: [clampedX, clampedY, 0],
-        rotation: [0, itemRotation, 0],
-        side,
-        wallId: event.node.id,
-        parentId: event.node.id,
-        metadata: { isTransient: true },
-      })
-
-      useScene.getState().createNode(node, event.node.id as AnyNodeId)
-      draftRef.current = node
-
-      const valid = !hasWallChildOverlap(event.node.id, clampedX, clampedY, width, height, node.id)
-
-      updateCursor(
-        wallLocalToWorld(
-          event.node,
-          clampedX,
-          clampedY,
-          getLevelYOffset(),
-          getSlabElevation(event),
-        ),
-        cursorRotation,
-        valid,
-      )
-
-      publishOpeningGuidesForWallEvent({
-        wall: event.node,
-        movingId: node.id,
-        centerS: clampedX,
-        centerY: clampedY,
-        width,
-        height,
-        includeVertical: true,
-        levelYOffset: getLevelYOffset(),
-        slabElevation: getSlabElevation(event),
-      })
-      event.stopPropagation()
-    }
-
-    const onWallMove = (event: WallEvent) => {
-      if (!isValidWallSideFace(event.normal)) {
-        destroyDraft()
-        showWallFallbackCursor(event)
-        return
-      }
-      if (isCurvedWall(event.node)) {
-        destroyDraft()
-        showWallFallbackCursor(event)
-        return
-      }
-      // Only interact with walls on the current level
-      if (event.node.parentId !== getLevelId()) {
-        destroyDraft()
-        showWallFallbackCursor(event)
-        return
-      }
-
-      const side = getSideFromNormal(event.normal)
-      const itemRotation = calculateItemRotation(event.normal)
-      const cursorRotation = calculateCursorRotation(event.normal, event.node.start, event.node.end)
-
-      const width = draftRef.current?.width ?? 1.5
-      const height = draftRef.current?.height ?? 1.5
-      const localX = resolveWallSlideAlignment({
-        wallNode: event.node,
-        rawLocalX: event.localPosition[0],
-        width,
-        candidates: alignmentCandidates,
-        bypass: event.nativeEvent?.altKey === true || event.nativeEvent?.shiftKey === true,
-        bypassSnap: event.nativeEvent?.shiftKey === true,
+        bypass,
+        bypassSnap,
      })
      const localY = resolvePlacementY({
-        event,
-        movingId: draftRef.current?.id ?? '',
+        wall,
+        movingId: ignoreId ?? '',
        localX,
+        rawLocalY,
        width,
        height,
+        bypassSnap,
      })
+      const { clampedX, clampedY } = clampToWall(wall, localX, localY, width, height)
+      const valid = !hasWallChildOverlap(wall.id, clampedX, clampedY, width, height, ignoreId)
+      return { clampedX, clampedY, valid }
+    }

-      const { clampedX, clampedY } = clampToWall(event.node, localX, localY, width, height)
+    // Shared create/update path for the wall draft — used by the direct
+    // wall-mesh hover and the floor proximity snap. Reuses the existing draft
+    // (reparenting only on an actual wall change to avoid churning the host's
+    // children array, which flashes 0-vertex wall geometry in WebGPU).
+    const applyWallTarget = (args: {
+      wall: WallNode
+      rawLocalX: number
+      rawLocalY: number
+      side: 'front' | 'back'
+      itemRotation: number
+      cursorRotationY: number
+      bypass: boolean
+      bypassSnap: boolean
+    }) => {
+      const {
+        wall,
+        rawLocalX,
+        rawLocalY,
+        side,
+        itemRotation,
+        cursorRotationY,
+        bypass,
+        bypassSnap,
+      } = args
+      const width = draftRef.current?.width ?? 1.5
+      const height = draftRef.current?.height ?? 1.5

-      // Draft may be null after a successful placement (the click handler
-      // deletes it and relies on the wall rebuild → pointer-enter cascade to
-      // recreate it). Recreate it here on the first subsequent move so the
-      // preview is ready for the next click without requiring a leave/enter.
      if (!draftRef.current) {
-        const levelId = getLevelId()
-        if (levelId && event.node.parentId === levelId) {
-          const node = WindowNode.parse({
-            position: [clampedX, clampedY, 0],
-            rotation: [0, itemRotation, 0],
-            side,
-            wallId: event.node.id,
-            parentId: event.node.id,
-            metadata: { isTransient: true },
-          })
-          useScene.getState().createNode(node, event.node.id as AnyNodeId)
-          draftRef.current = node
-        }
+        const node = WindowNode.parse({
+          position: [0, DEFAULT_SILL_CENTER_Y, 0],
+          rotation: [0, itemRotation, 0],
+          side,
+          wallId: wall.id,
+          parentId: wall.id,
+          metadata: { isTransient: true },
+        })
+        useScene.getState().createNode(node, wall.id as AnyNodeId)
+        draftRef.current = node
      }

-      if (draftRef.current) {
-        // Update the scene store on every move so the 2D floor plan
-        // stays in sync (it re-renders from `node.position`). Only
-        // forward `parentId` / `wallId` when the wall actually changed
-        // — otherwise the reparent path churns the host wall's
-        // `children` array every tick, which re-renders the wall and
-        // briefly draws its 0-vertex placeholder geometry (WebGPU then
-        // flags "Vertex buffer slot 0 ... was not set").
-        const isSameWall = event.node.id === draftRef.current.parentId
-        if (isSameWall) {
-          useScene.getState().updateNode(draftRef.current.id, {
-            position: [clampedX, clampedY, 0],
-            rotation: [0, itemRotation, 0],
-            side,
-          })
-          markHostDirty(event.node.id)
-        } else {
-          useScene.getState().updateNode(draftRef.current.id, {
-            position: [clampedX, clampedY, 0],
-            rotation: [0, itemRotation, 0],
-            side,
-            parentId: event.node.id,
-            wallId: event.node.id,
-            // The draft may arrive from a roof-segment face hover.
-            roofSegmentId: undefined,
-            roofFace: undefined,
-          })
-        }
-      }
-
-      const valid = !hasWallChildOverlap(
-        event.node.id,
-        clampedX,
-        clampedY,
+      const { clampedX, clampedY, valid } = resolveWallPlacement(
+        wall,
+        rawLocalX,
+        rawLocalY,
        width,
        height,
-        draftRef.current?.id,
+        bypass,
+        bypassSnap,
+        draftRef.current.id,
      )

+      if (wall.id === draftRef.current.parentId) {
+        useScene.getState().updateNode(draftRef.current.id, {
+          position: [clampedX, clampedY, 0],
+          rotation: [0, itemRotation, 0],
+          side,
+        })
+        markHostDirty(wall.id)
+      } else {
+        useScene.getState().updateNode(draftRef.current.id, {
+          position: [clampedX, clampedY, 0],
+          rotation: [0, itemRotation, 0],
+          side,
+          parentId: wall.id,
+          wallId: wall.id,
+          // The draft may arrive from a roof-segment face hover.
+          roofSegmentId: undefined,
+          roofFace: undefined,
+        })
+      }
+
      updateCursor(
        wallLocalToWorld(
-          event.node,
+          wall,
          clampedX,
          clampedY,
          getLevelYOffset(),
-          getSlabElevation(event),
+          getSlabElevationForWall(wall),
        ),
-        cursorRotation,
+        cursorRotationY,
        valid,
      )

      if (draftRef.current) {
        publishOpeningGuidesForWallEvent({
-          wall: event.node,
+          wall,
          movingId: draftRef.current.id,
          centerS: clampedX,
          centerY: clampedY,
@@ -370,79 +326,44 @@ const WindowTool: React.FC = () => {
          height,
          includeVertical: true,
          levelYOffset: getLevelYOffset(),
-          slabElevation: getSlabElevation(event),
+          slabElevation: getSlabElevationForWall(wall),
        })
      }
-      event.stopPropagation()
+      return { clampedX, clampedY, valid }
    }

-    const onWallClick = (event: WallEvent) => {
-      if (!draftRef.current) return
-      if (!isValidWallSideFace(event.normal)) return
-      if (isCurvedWall(event.node)) return
-      // Only interact with walls on the current level
-      if (event.node.parentId !== getLevelId()) return
-
-      const side = getSideFromNormal(event.normal)
-      const itemRotation = calculateItemRotation(event.normal)
-
-      const localX = resolveWallSlideAlignment({
-        wallNode: event.node,
-        rawLocalX: event.localPosition[0],
-        width: draftRef.current.width,
-        candidates: alignmentCandidates,
-        bypass: event.nativeEvent?.altKey === true || event.nativeEvent?.shiftKey === true,
-        bypassSnap: event.nativeEvent?.shiftKey === true,
-      })
-      const localY = resolvePlacementY({
-        event,
-        movingId: draftRef.current.id,
-        localX,
-        width: draftRef.current.width,
-        height: draftRef.current.height,
-      })
-      const { clampedX, clampedY } = clampToWall(
-        event.node,
-        localX,
-        localY,
-        draftRef.current.width,
-        draftRef.current.height,
-      )
-      const valid = !hasWallChildOverlap(
-        event.node.id,
-        clampedX,
-        clampedY,
-        draftRef.current.width,
-        draftRef.current.height,
-        draftRef.current.id,
-      )
-      if (!valid) return
-
+    // Promote the draft into a permanent window. Shared by the wall-mesh click
+    // and the floor proximity click.
+    const commitWindowAtWall = (
+      wall: WallNode,
+      clampedX: number,
+      clampedY: number,
+      side: 'front' | 'back',
+      itemRotation: number,
+    ) => {
      const draft = draftRef.current
+      if (!draft) return
      draftRef.current = null
+      hostKind = null

-      // Delete transient draft (paused, invisible to undo)
      useScene.getState().deleteNode(draft.id)
-
-      // Resume → create permanent node (single undoable action)
      useScene.temporal.getState().resume()

      const levelId = getLevelId()
      const state = useScene.getState()
      const windowCount = Object.values(state.nodes).filter((n) => {
        if (n.type !== 'window') return false
-        const wall = n.parentId ? state.nodes[n.parentId as AnyNodeId] : undefined
-        return wall?.parentId === levelId
+        const w = n.parentId ? state.nodes[n.parentId as AnyNodeId] : undefined
+        return w?.parentId === levelId
      }).length
-      const name = `Window ${windowCount + 1}`

      const node = WindowNode.parse({
-        name,
+        name: `Window ${windowCount + 1}`,
        position: [clampedX, clampedY, 0],
        rotation: [0, itemRotation, 0],
        side,
-        wallId: event.node.id,
-        parentId: event.node.id,
+        wallId: wall.id,
+        parentId: wall.id,
        width: draft.width,
        height: draft.height,
        windowType: draft.windowType,
@@ -461,20 +382,110 @@ const WindowTool: React.FC = () => {
        sillThickness: draft.sillThickness,
      })

-      useScene.getState().createNode(node, event.node.id as AnyNodeId)
+      useScene.getState().createNode(node, wall.id as AnyNodeId)
      useViewer.getState().setSelection({ selectedIds: [node.id] })
      useScene.temporal.getState().pause()
      triggerSFX('sfx:structure-build')
      alignmentCandidates = collectAlignmentAnchors(useScene.getState().nodes, '')
      useAlignmentGuides.getState().clear()
      clearOpeningGuides3D()
+    }

+    // ── Direct wall-mesh hover ──────────────────────────────────────
+    const onWallHover = (event: WallEvent) => {
+      hostKind = 'wall'
+      lastMeshEventTime = event.nativeEvent?.timeStamp ?? -1
+      if (
+        !isValidWallSideFace(event.normal) ||
+        isCurvedWall(event.node) ||
+        event.node.parentId !== getLevelId()
+      ) {
+        destroyDraft()
+        showWallFallbackCursor(event)
+        return
+      }
+      lastWallEvent = event
+
+      const faceSide = getSideFromNormal(event.normal)
+      const side = sideFlip ? (faceSide === 'front' ? 'back' : 'front') : faceSide
+      const flipOffset = sideFlip ? Math.PI : 0
+      const itemRotation = calculateItemRotation(event.normal) + flipOffset
+      const cursorRotation =
+        calculateCursorRotation(event.normal, event.node.start, event.node.end) + flipOffset
+      const bypassSnap = event.nativeEvent?.shiftKey === true
+      const bypass = event.nativeEvent?.altKey === true || bypassSnap
+
+      applyWallTarget({
+        wall: event.node,
+        rawLocalX: event.localPosition[0],
+        rawLocalY: event.localPosition[1],
+        side,
+        itemRotation,
+        cursorRotationY: cursorRotation,
+        bypass,
+        bypassSnap,
+      })
+      event.stopPropagation()
+    }
+
+    const onWallClick = (event: WallEvent) => {
+      if (!draftRef.current) return
+      if (
+        !isValidWallSideFace(event.normal) ||
+        isCurvedWall(event.node) ||
+        event.node.parentId !== getLevelId()
+      ) {
+        return
+      }
+
+      const faceSide = getSideFromNormal(event.normal)
+      const side = sideFlip ? (faceSide === 'front' ? 'back' : 'front') : faceSide
+      const itemRotation = calculateItemRotation(event.normal) + (sideFlip ? Math.PI : 0)
+      const bypassSnap = event.nativeEvent?.shiftKey === true
+      const bypass = event.nativeEvent?.altKey === true || bypassSnap
+
+      const { clampedX, clampedY, valid } = resolveWallPlacement(
+        event.node,
+        event.localPosition[0],
+        event.localPosition[1],
+        draftRef.current.width,
+        draftRef.current.height,
+        bypass,
+        bypassSnap,
+        draftRef.current.id,
+      )
+      if (!valid) return
+
+      commitWindowAtWall(event.node, clampedX, clampedY, side, itemRotation)
      event.stopPropagation()
    }

    const onWallLeave = () => {
+      if (hostKind !== 'wall') return
+      lastWallEvent = null
      destroyDraft()
      hideCursor()
+      hostKind = null
+    }
+
+    // ── Floor free-follow ───────────────────────────────────────────
+    // Over open floor the ghost follows the cursor like a moving item. It does
+    // NOT snap from proximity — snapping engages only when the cursor ray
+    // actually hovers a wall (onWallHover) or roof face (onRoofHover).
+    const onGridFreeFollow = (event: GridEvent) => {
+      if (useViewer.getState().cameraDragging) return
+      // A wall/roof mesh handler processed this exact pointermove (R3F + the
+      // grid raycast share the source DOM event's timeStamp) — it owns the
+      // frame and has snapped the draft, so skip the floor follow this tick.
+      const ts = event.nativeEvent?.timeStamp ?? -1
+      if (ts === lastMeshEventTime) return
+      // Fresh floor-only frame: the cursor is off any wall/roof. Drop any draft
+      // and free-follow the cursor with the invalid (unplaceable) ghost.
+      hostKind = null
+      lastWallEvent = null
+      const [x, y, z] = event.localPosition
+      destroyDraft()
+      showGhostAt([x, y + FALLBACK_HEIGHT / 2 + FALLBACK_SILL_LIFT, z])
    }

    // ── Roof-segment wall faces ─────────────────────────────────────
@@ -501,6 +512,8 @@ const WindowTool: React.FC = () => {
    }

    const onRoofHover = (event: RoofEvent) => {
+      hostKind = 'roof'
+      lastMeshEventTime = event.nativeEvent?.timeStamp ?? -1
      const target = resolveRoofTarget(event)
      if (!target) {
        // On the roof but not over a placeable wall face (slope, soffit,
@@ -545,6 +558,7 @@ const WindowTool: React.FC = () => {

      const draft = draftRef.current
      draftRef.current = null
+      hostKind = null

      useScene.getState().deleteNode(draft.id)
      useScene.temporal.getState().resume()
@@ -591,26 +605,44 @@ const WindowTool: React.FC = () => {
    }

    const onRoofLeave = () => {
-      if (!draftRef.current?.roofSegmentId) return
+      if (hostKind !== 'roof') return
      destroyDraft()
      hideCursor()
+      hostKind = null
    }

    const onCancel = () => {
      destroyDraft()
      hideCursor()
+      hostKind = null
    }

-    emitter.on('wall:enter', onWallEnter)
-    emitter.on('wall:move', onWallMove)
+    // 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.
+    const onKeyDown = (e: KeyboardEvent) => {
+      if (e.key !== 'r' && e.key !== 'R') return
+      if (!lastWallEvent) 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)
+    }
+
+    emitter.on('wall:enter', onWallHover)
+    emitter.on('wall:move', onWallHover)
    emitter.on('wall:click', onWallClick)
    emitter.on('wall:leave', onWallLeave)
    emitter.on('roof:enter', onRoofHover)
    emitter.on('roof:move', onRoofHover)
    emitter.on('roof:click', onRoofClick)
    emitter.on('roof:leave', onRoofLeave)
-    emitter.on('grid:move', showFallbackCursor)
+    emitter.on('grid:move', onGridFreeFollow)
    emitter.on('tool:cancel', onCancel)
+    window.addEventListener('keydown', onKeyDown)

    return () => {
      destroyDraft()
@@ -618,16 +650,17 @@ const WindowTool: React.FC = () => {
      useAlignmentGuides.getState().clear()
      clearOpeningGuides3D()
      useScene.temporal.getState().resume()
-      emitter.off('wall:enter', onWallEnter)
-      emitter.off('wall:move', onWallMove)
+      emitter.off('wall:enter', onWallHover)
+      emitter.off('wall:move', onWallHover)
      emitter.off('wall:click', onWallClick)
      emitter.off('wall:leave', onWallLeave)
      emitter.off('roof:enter', onRoofHover)
      emitter.off('roof:move', onRoofHover)
      emitter.off('roof:click', onRoofClick)
      emitter.off('roof:leave', onRoofLeave)
-      emitter.off('grid:move', showFallbackCursor)
+      emitter.off('grid:move', onGridFreeFollow)
      emitter.off('tool:cancel', onCancel)
+      window.removeEventListener('keydown', onKeyDown)
    }
  }, [])

@@ -643,14 +676,21 @@ const WindowTool: React.FC = () => {
  useEffect(() => () => edgesGeo.dispose(), [edgesGeo])

  return (
-    <group ref={cursorGroupRef} visible={false}>
-      <lineSegments
-        geometry={edgesGeo}
-        layers={EDITOR_LAYER}
-        material={edgeMaterial}
-        ref={edgesRef}
-      />
-    </group>
+    <>
+      <group ref={cursorGroupRef} visible={false}>
+        <lineSegments
+          geometry={edgesGeo}
+          layers={EDITOR_LAYER}
+          material={edgeMaterial}
+          ref={edgesRef}
+        />
+      </group>
+      {fallbackPose && (
+        <group position={fallbackPose.position} rotation-y={fallbackPose.rotationY}>
+          <WindowPreview invalid node={ghostStub} />
+        </group>
+      )}
+    </>
  )
 }