fix(editor): preserve grab offset when moving items (no teleport-to-cursor) (#416)

* fix(editor): preserve grab offset when moving items (no teleport-to-cursor)

Grabbing a placed item to move it (move-cross handle or the Move
affordance) snapped the item's origin to the cursor instead of keeping
the offset between the grab point and the origin.

- Floor (regression): the grab-offset rewrite patched event.localPosition,
  but floorStrategy.move reads event.position (the world cursor) for its
  world-grid snap on the default non-Shift path -- a read added after the
  offset fix landed. Now also correct event.position, derived from the
  corrected building-local point via buildingLocalToWorld.
- Wall / ceiling / item-surface / shelf: the shared surface strategies
  snapped the origin straight to the cursor with no grab offset. Added
  per-surface grab anchors (start + (raw - anchor)) seeded on the first
  move per host and reset on leave/detach; host-resting items start in
  their surface, and the level-reparent effect skips intentionally-hosted
  drafts so the dragged mesh stays on its host.

Rename preserveFloorDragOffset -> preserveDragOffset (it now governs all
surfaces). 2D move paths already preserved the grab offset, so no sibling
change is needed -- this brings 3D into parity.

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

* refactor(editor): tidy grab-offset floor/wall paths (quality pass)

Behaviour-preserving readability pass before shipping:
- Extract the floor grab-offset IIFE into a named `applyFloorGrabOffset`
  helper (parity with `resolveHostSurfaceWorld`); drop redundant tuple
  casts via the return annotation and tighten the comment.
- Wall move: always set `position` (raw hit when the wall mesh is absent)
  instead of a conditional object spread.

A reviewed dedup of the three per-surface anchors was deliberately NOT
taken — the wall (X/Y) / ceiling (X/Z) / host-surface frames are
heterogeneous enough that unifying them adds more indirection than it
removes.

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

---------

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

packages/editor/src/components/tools/item/use-placement-coordinator.tsx

@@ -192,8 +192,10 @@ export interface PlacementCoordinatorConfig {
   initialState?: PlacementState
   /** Scale to use when lazily creating a draft (e.g. for wall/ceiling duplicates). Defaults to [1,1,1]. */
   defaultScale?: [number, number, number]
-  /** Move-mode sessions for floor items keep the grabbed item offset from the first floor-plane hit. */
+  /** Move-mode sessions keep the grabbed item offset from the first surface hit
-  preserveFloorDragOffset?: boolean
+   *  (floor / wall / ceiling / item-surface / shelf) instead of snapping the
+   *  item's origin under the cursor. */
+  preserveDragOffset?: boolean
 }
 
 export function usePlacementCoordinator(config: PlacementCoordinatorConfig): React.ReactNode {
@@ -461,6 +463,12 @@ export function usePlacementCoordinator(config: PlacementCoordinatorConfig): Rea
       return buildingMesh ? buildingMesh.worldToLocal(new Vector3(x, y, z)) : new Vector3(x, y, z)
     }
 
+    const buildingLocalToWorld = (x: number, y: number, z: number): Vector3 => {
+      const buildingId = useViewer.getState().selection.buildingId
+      const buildingMesh = buildingId ? sceneRegistry.nodes.get(buildingId as AnyNodeId) : null
+      return buildingMesh ? buildingMesh.localToWorld(new Vector3(x, y, z)) : new Vector3(x, y, z)
+    }
+
     const applyTransition = (result: TransitionResult) => {
       // Alignment guides are floor-only; clear them when the cursor moves
       // onto a wall / ceiling / item surface (only those paths call this).
@@ -528,11 +536,95 @@ export function usePlacementCoordinator(config: PlacementCoordinatorConfig): Rea
 
     // ---- Init draft ----
     configRef.current.initDraft(gridPosition.current)
-    const preserveFloorDragOffset =
+    const preserveDragOffset = configRef.current.preserveDragOffset === true
-      configRef.current.preserveFloorDragOffset === true &&
+    const relativeFloorStart =
-      placementState.current.surface === 'floor' &&
+      preserveDragOffset && placementState.current.surface === 'floor' && !asset.attachTo
-      !asset.attachTo
+        ? gridPosition.current.clone()
-    const relativeFloorStart = preserveFloorDragOffset ? gridPosition.current.clone() : null
+        : null
+
+    // Grab anchors for the non-floor surfaces. Each captures the cursor's
+    // surface-local position and the item's stored position on the first move
+    // for a given host, then offsets every later move by
+    // `start + (raw - anchor)` — mirroring the floor path and the door/window
+    // move tools so the item tracks the grabbed point instead of teleporting
+    // its origin under the cursor. Reset on host change (re-seeded from the
+    // item's then-current position) by the surface leave handlers.
+    let wallDragAnchor: {
+      wallId: string
+      rawX: number
+      rawY: number
+      startX: number
+      startY: number
+    } | null = null
+    let ceilingDragAnchor: {
+      ceilingId: string
+      rawX: number
+      rawZ: number
+      startX: number
+      startZ: number
+    } | null = null
+    let hostSurfaceDragAnchor: {
+      hostId: string
+      rawX: number
+      rawZ: number
+      startX: number
+      startZ: number
+    } | null = null
+
+    // Item-surface / shelf moves snap from a WORLD cursor hit projected into the
+    // host's local frame. Re-project the offset-corrected local point back to
+    // world so the strategy (which re-derives both the stored position and the
+    // visual cursor from `event.position`) stays self-consistent.
+    const resolveHostSurfaceWorld = (
+      hostId: string,
+      worldPos: readonly [number, number, number],
+    ): [number, number, number] | null => {
+      const draft = draftNode.current
+      const hostMesh = sceneRegistry.nodes.get(hostId)
+      if (!(preserveDragOffset && draft && hostMesh)) return null
+      const rawLocal = hostMesh.worldToLocal(new Vector3(worldPos[0], worldPos[1], worldPos[2]))
+      if (!hostSurfaceDragAnchor || hostSurfaceDragAnchor.hostId !== hostId) {
+        hostSurfaceDragAnchor = {
+          hostId,
+          rawX: rawLocal.x,
+          rawZ: rawLocal.z,
+          startX: draft.position[0],
+          startZ: draft.position[2],
+        }
+      }
+      const correctedX = hostSurfaceDragAnchor.startX + (rawLocal.x - hostSurfaceDragAnchor.rawX)
+      const correctedZ = hostSurfaceDragAnchor.startZ + (rawLocal.z - hostSurfaceDragAnchor.rawZ)
+      const world = hostMesh.localToWorld(new Vector3(correctedX, rawLocal.y, correctedZ))
+      return [world.x, world.y, world.z]
+    }
+
+    // Floor grab-offset: the item tracks the grabbed point instead of snapping
+    // its origin under the cursor. `floorStrategy.move` snaps on the WORLD grid
+    // (`event.position`) on its default path and only reads `event.localPosition`
+    // under Shift, so both frames must carry the offset; the world point is
+    // derived from the corrected local one so the two stay consistent.
+    const applyFloorGrabOffset = (event: GridEvent): GridEvent => {
+      if (relativeFloorStart === null) return event
+      const rawX = event.localPosition[0]
+      const rawZ = event.localPosition[2]
+      const anchor = floorDragAnchor ?? [rawX, rawZ]
+      floorDragAnchor = anchor
+      const correctedLocal: [number, number, number] = [
+        relativeFloorStart.x + (rawX - anchor[0]),
+        event.localPosition[1],
+        relativeFloorStart.z + (rawZ - anchor[1]),
+      ]
+      const correctedWorld = buildingLocalToWorld(
+        correctedLocal[0],
+        correctedLocal[1],
+        correctedLocal[2],
+      )
+      return {
+        ...event,
+        position: [correctedWorld.x, event.position[1], correctedWorld.z],
+        localPosition: correctedLocal,
+      }
+    }
 
     // Sync cursor to the draft mesh's world position and rotation
     if (draftNode.current) {
@@ -656,23 +748,7 @@ export function usePlacementCoordinator(config: PlacementCoordinatorConfig): Rea
         detachItemSurfaceToFloor(event as unknown as ItemEvent)
       }
 
-      const floorEvent =
+      const floorEvent = applyFloorGrabOffset(event)
-        relativeFloorStart !== null
-          ? (() => {
-              const rawX = event.localPosition[0]
-              const rawZ = event.localPosition[2]
-              const anchor = floorDragAnchor ?? [rawX, rawZ]
-              floorDragAnchor = anchor
-              return {
-                ...event,
-                localPosition: [
-                  relativeFloorStart.x + (rawX - anchor[0]),
-                  event.localPosition[1],
-                  relativeFloorStart.z + (rawZ - anchor[1]),
-                ] as [number, number, number],
-              }
-            })()
-          : event
 
       lastRawPos.current.set(
         floorEvent.localPosition[0],
@@ -865,7 +941,37 @@ export function usePlacementCoordinator(config: PlacementCoordinatorConfig): Rea
         return
       }
 
-      const result = wallStrategy.move(ctx, event, getActiveValidators())
+      let wallMoveEvent = event
+      if (preserveDragOffset && draftNode.current) {
+        const rawX = event.localPosition[0]
+        const rawY = event.localPosition[1]
+        if (!wallDragAnchor || wallDragAnchor.wallId !== event.node.id) {
+          wallDragAnchor = {
+            wallId: event.node.id,
+            rawX,
+            rawY,
+            startX: draftNode.current.position[0],
+            startY: draftNode.current.position[1],
+          }
+        }
+        const correctedX = wallDragAnchor.startX + (rawX - wallDragAnchor.rawX)
+        const correctedY = wallDragAnchor.startY + (rawY - wallDragAnchor.rawY)
+        const wallMesh = sceneRegistry.nodes.get(event.node.id)
+        // Derive the world cursor from the corrected wall-local point so the
+        // visual cursor (world) and the stored position (wall-local) agree; if
+        // the wall mesh is somehow absent, keep the raw world hit unchanged.
+        const correctedWorld = wallMesh
+          ? wallMesh.localToWorld(new Vector3(correctedX, correctedY, event.localPosition[2]))
+          : null
+        wallMoveEvent = {
+          ...event,
+          localPosition: [correctedX, correctedY, event.localPosition[2]],
+          position: correctedWorld
+            ? [correctedWorld.x, correctedWorld.y, correctedWorld.z]
+            : event.position,
+        }
+      }
+      const result = wallStrategy.move(ctx, wallMoveEvent, getActiveValidators())
       if (!result) return
 
       event.stopPropagation()
@@ -962,6 +1068,7 @@ export function usePlacementCoordinator(config: PlacementCoordinatorConfig): Rea
     }
 
     const onWallLeave = (event: WallEvent) => {
+      wallDragAnchor = null
       const result = wallStrategy.leave(getContext())
       if (!result) return
 
@@ -1133,6 +1240,7 @@ export function usePlacementCoordinator(config: PlacementCoordinatorConfig): Rea
     // ---- Item Surface Handlers ----
 
     const detachItemSurfaceToFloor = (event: ItemEvent) => {
+      hostSurfaceDragAnchor = null
       const buildingLocalPoint = worldToBuildingLocal(
         event.position[0],
         event.position[1],
@@ -1233,8 +1341,17 @@ export function usePlacementCoordinator(config: PlacementCoordinatorConfig): Rea
         return
       }
 
-      lastRawPos.current.set(event.position[0], event.position[1], event.position[2])
+      const surfaceWorld =
-      const result = itemSurfaceStrategy.move(ctx, event)
+        ctx.state.surfaceItemId !== null
+          ? resolveHostSurfaceWorld(ctx.state.surfaceItemId, event.position)
+          : null
+      const itemMoveEvent = surfaceWorld ? { ...event, position: surfaceWorld } : event
+      lastRawPos.current.set(
+        itemMoveEvent.position[0],
+        itemMoveEvent.position[1],
+        itemMoveEvent.position[2],
+      )
+      const result = itemSurfaceStrategy.move(ctx, itemMoveEvent)
       if (!result) return
 
       event.stopPropagation()
@@ -1428,8 +1545,34 @@ export function usePlacementCoordinator(config: PlacementCoordinatorConfig): Rea
         return
       }
 
-      lastRawPos.current.set(event.localPosition[0], event.localPosition[1], event.localPosition[2])
+      let ceilingMoveEvent = event
-      const result = ceilingStrategy.move(getContext(), event)
+      if (preserveDragOffset && draftNode.current) {
+        const rawX = event.localPosition[0]
+        const rawZ = event.localPosition[2]
+        if (!ceilingDragAnchor || ceilingDragAnchor.ceilingId !== event.node.id) {
+          ceilingDragAnchor = {
+            ceilingId: event.node.id,
+            rawX,
+            rawZ,
+            startX: draftNode.current.position[0],
+            startZ: draftNode.current.position[2],
+          }
+        }
+        ceilingMoveEvent = {
+          ...event,
+          localPosition: [
+            ceilingDragAnchor.startX + (rawX - ceilingDragAnchor.rawX),
+            event.localPosition[1],
+            ceilingDragAnchor.startZ + (rawZ - ceilingDragAnchor.rawZ),
+          ],
+        }
+      }
+      lastRawPos.current.set(
+        ceilingMoveEvent.localPosition[0],
+        ceilingMoveEvent.localPosition[1],
+        ceilingMoveEvent.localPosition[2],
+      )
+      const result = ceilingStrategy.move(getContext(), ceilingMoveEvent)
       if (!result) return
 
       event.stopPropagation()
@@ -1493,6 +1636,7 @@ export function usePlacementCoordinator(config: PlacementCoordinatorConfig): Rea
     }
 
     const onCeilingLeave = (event: CeilingEvent) => {
+      ceilingDragAnchor = null
       const result = ceilingStrategy.leave(getContext())
       if (!result) return
 
@@ -1566,7 +1710,12 @@ export function usePlacementCoordinator(config: PlacementCoordinatorConfig): Rea
         }
         return
       }
-      const result = shelfSurfaceStrategy.move(ctx, event)
+      const shelfWorld =
+        ctx.state.shelfId !== null
+          ? resolveHostSurfaceWorld(ctx.state.shelfId, event.position)
+          : null
+      const shelfMoveEvent = shelfWorld ? { ...event, position: shelfWorld } : event
+      const result = shelfSurfaceStrategy.move(ctx, shelfMoveEvent)
       if (!result) return
 
       event.stopPropagation()
@@ -1905,6 +2054,16 @@ export function usePlacementCoordinator(config: PlacementCoordinatorConfig): Rea
     const draft = draftNode.current
     if (!(draft && viewerLevelId) || asset.attachTo) return
     if (draft.parentId === viewerLevelId) return
+    // A non-attach item resting on a host surface (table / counter / shelf) is
+    // intentionally parented to that host while it's moved — the surface move
+    // handlers keep it hosted and the commit writes the host parent back. Only
+    // free floor items get re-homed to the level here; yanking a hosted item
+    // onto the level would re-interpret its host-local position in level space
+    // and float the dragged mesh off the host toward the building origin.
+    const draftParent = draft.parentId
+      ? useScene.getState().nodes[draft.parentId as AnyNodeId]
+      : undefined
+    if (draftParent?.type === 'item' || draftParent?.type === 'shelf') return
     draft.parentId = viewerLevelId
     useScene.getState().updateNode(draft.id as AnyNodeId, { parentId: viewerLevelId })
   }, [viewerLevelId, draftNode, asset])

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

@@ -1,6 +1,6 @@
 'use client'
 
-import type { ItemNode } from '@pascal-app/core'
+import { type AnyNodeId, type ItemNode, useScene } from '@pascal-app/core'
 import {
   type PlacementState,
   triggerSFX,
@@ -67,6 +67,32 @@ function getInitialState(node: ItemNode): PlacementState {
       shelfId: null,
     }
   }
+  // A floor item resting on a host surface (table / counter / shelf) starts in
+  // that surface, not 'floor', so the first pointer move runs the surface move
+  // handler — which preserves the grab offset — instead of a fresh `enter()`
+  // that snaps the item's origin under the cursor. Without this the item
+  // teleports the instant it's grabbed.
+  const parent = node.parentId ? useScene.getState().nodes[node.parentId as AnyNodeId] : undefined
+  if (parent?.type === 'item') {
+    return {
+      surface: 'item-surface',
+      wallId: null,
+      roofSegmentId: null,
+      ceilingId: null,
+      surfaceItemId: node.parentId,
+      shelfId: null,
+    }
+  }
+  if (parent?.type === 'shelf') {
+    return {
+      surface: 'shelf-surface',
+      wallId: null,
+      roofSegmentId: null,
+      ceilingId: null,
+      surfaceItemId: null,
+      shelfId: node.parentId,
+    }
+  }
   return {
     surface: 'floor',
     wallId: null,
@@ -102,7 +128,7 @@ export function MoveItemTool({ node }: { node: ItemNode }) {
       : getInitialState(node),
     // Preserve the original item's scale so Y-position calculations use the correct height.
     defaultScale: isNew ? node.scale : undefined,
-    preserveFloorDragOffset: true,
+    preserveDragOffset: true,
     initDraft: (gridPosition) => {
       if (isNew) {
         // Duplicate: floor items get a draft immediately; wall/ceiling