fix(editor): harden editor interactions and WebGPU rendering

Fix editor bug sweep regressions, WebGPU CSG/material crashes, Shift snap bypass behavior, arrow handle drag projection, and the wall preview null guard covered by the Sentry follow-up PRs.

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

@@ -63,7 +63,7 @@ export const columnFloorplanMoveTarget: FloorplanMoveTarget<ColumnNode> = ({ nod
         return Math.round(value / step) * step
       }
       const gridSnapped = resolveCursor(planPoint, { snap }) as WallPlanPoint
-      // Figma-style alignment layered on the grid snap (Alt bypasses).
+      // Figma-style alignment layered on the grid snap (Alt bypasses alignment; Shift all snap).
       const { point: snapped } = applyFloorplanAlignment(
         gridSnapped,
         movingFootprintAnchors(
@@ -73,13 +73,13 @@ export const columnFloorplanMoveTarget: FloorplanMoveTarget<ColumnNode> = ({ nod
           rotationY,
         ),
         candidates,
-        { bypass: modifiers.altKey },
+        { bypass: modifiers.altKey || modifiers.shiftKey },
       )
       const next: [number, number, number] = [snapped[0], originalPosition[1], snapped[1]]
       lastPosition = next
 
       const snapKey = `${snapped[0]},${snapped[1]}`
-      if (snapKey !== lastSnapKey) {
+      if (!modifiers.shiftKey && snapKey !== lastSnapKey) {
         triggerSFX('sfx:grid-snap')
         lastSnapKey = snapKey
       }

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

@@ -50,8 +50,8 @@ const snapToGridStep = (value: number) => {
   return Math.round(value / step) * step
 }
 
-/** 90° steps, matching the GLB item / shelf placement rotation. */
-const ROTATION_STEP = Math.PI / 2
+/** 45° steps, matching the generic move tool's R/T rotation. */
+const ROTATION_STEP = Math.PI / 4
 
 /** Figma-style alignment-snap threshold (meters), matching the other tools. */
 const ALIGNMENT_THRESHOLD_M = 0.08
@@ -124,15 +124,15 @@ function MoveColumnTool({ node }: { node: ColumnNode }) {
         original: [node.position[0], node.position[2]],
         anchor: dragAnchor,
         mode: useAbsoluteCursorPlacement ? 'absolute' : 'relative',
-        snap: snapToGridStep,
+        snap: event.nativeEvent?.shiftKey === true ? (value) => value : snapToGridStep,
       })
       dragAnchor = resolved.anchor
       let [x, z] = resolved.point
 
-      // Figma-style alignment snap on top of grid snap; Alt bypasses. The
+      // Figma-style alignment snap on top of grid snap; Alt bypasses alignment; Shift all snap. The
       // guide connects to the candidate's nearest real anchor (resolver
       // tie-break), so the dot always sits on an actual point.
-      const bypass = event.nativeEvent?.altKey === true
+      const bypass = event.nativeEvent?.altKey === true || event.nativeEvent?.shiftKey === true
       if (!bypass && alignmentCandidates.length > 0) {
         const result = resolveAlignment({
           moving: movingFootprintAnchors(node, x, z, rotationY),
@@ -151,7 +151,7 @@ function MoveColumnTool({ node }: { node: ColumnNode }) {
       applyPreview([x, 0, z])
     }
 
-    // R / T rotate the dragged column about Y in 90° steps (matches the move
+    // R / T rotate the dragged column about Y in 45° steps (matches the move
     // HUD's "Rotate" hints), committed on drop.
     const onKeyDown = (e: KeyboardEvent) => {
       if (e.metaKey || e.ctrlKey || e.altKey) return

packages/nodes/src/column/tool.tsx

@@ -87,7 +87,8 @@ const ColumnTool = () => {
         rawZ: event.localPosition[2],
         gridStep: useEditor.getState().gridSnapStep,
         candidates: alignmentCandidates,
-        bypassAlignment: event.nativeEvent?.altKey === true,
+        bypassAlignment: event.nativeEvent?.altKey === true || event.nativeEvent?.shiftKey === true,
+        bypassGrid: event.nativeEvent?.shiftKey === true,
       })
       useAlignmentGuides.getState().set(guides)
 
@@ -107,7 +108,10 @@ const ColumnTool = () => {
       usePlacementPreview.getState().set({ ...previewNode, position })
 
       const prev = previousSnapRef.current
-      if (!prev || prev[0] !== position[0] || prev[1] !== position[2]) {
+      if (
+        event.nativeEvent?.shiftKey !== true &&
+        (!prev || prev[0] !== position[0] || prev[1] !== position[2])
+      ) {
         triggerSFX('sfx:grid-snap')
         previousSnapRef.current = [position[0], position[2]]
       }
@@ -116,7 +120,12 @@ const ColumnTool = () => {
     const commitAtCursor = (event: FloorPlacementClickTriggerEvent) => {
       const position =
         lastCursorRef.current ??
-        getLevelLocalSnappedPosition(activeLevelId, event, useEditor.getState().gridSnapStep)
+        getLevelLocalSnappedPosition(
+          activeLevelId,
+          event,
+          useEditor.getState().gridSnapStep,
+          event.nativeEvent?.shiftKey === true,
+        )
 
       const column = createColumnFromPreset(DEFAULT_COLUMN_PRESET_ID, position)
       useScene.getState().createNode(column, activeLevelId)