fix(viewer): bake folding/garage doors at an un-flipped rest pose

`poseDoorMovingParts` assigned a single euler axis (`group.rotation.y` /
`.x`). The live system was fine because the group's euler stays a clean
(0, y, 0). But the GLB exporter clones the door and decomposes its matrix,
which re-derives a gimbal-flipped euler (x=z=π) for any rotation beyond
±90° — folding panels reach ~158°. The reset to t=0 then only zeroed `.y`,
leaving the π residue on x/z and baking a 180°-flipped rest pose (panels
folded out toward a wrong position even when closed).

Set the full euler triple via `.set()` in every pose branch so the other
two axes are always zeroed, clearing any decomposed residue. Add a
regression test that exports an open folding door and asserts an identity
rest pose for all panels.

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

packages/editor/src/lib/glb-export.test.ts

@@ -1,6 +1,7 @@
 import { afterEach, describe, expect, test } from 'bun:test'
-import { type AnyNode, sceneRegistry } from '@pascal-app/core'
+import { type AnyNode, DoorNode, sceneRegistry } from '@pascal-app/core'
 import * as THREE from 'three'
+import { buildDoorPreviewMesh } from '@pascal-app/viewer'
 import { prepareSceneForExport } from './glb-export'
 
 afterEach(() => {
@@ -360,4 +361,33 @@ describe('prepareSceneForExport', () => {
     const lastScaleY = scaleTrack!.values[scaleTrack!.values.length - 2]!
     expect(lastScaleY).toBeLessThan(0.1)
   })
+
+  // Regression: a folding door saved in an open state (|fold angle| > π/2) used
+  // to bake a 180°-flipped rest pose. The export clones + decomposes the door
+  // matrix, which re-derives a gimbal-flipped euler (x=z=π) for the wide Y
+  // rotation; the pose reset must zero the full euler triple, not just `.y`.
+  test('bakes an identity rest pose for an open folding door', () => {
+    const node = DoorNode.parse({
+      id: 'door_folding',
+      doorType: 'folding',
+      leafCount: 4,
+      operationState: 0.65,
+    })
+    const mesh = buildDoorPreviewMesh(node)
+    const root = new THREE.Group()
+    root.add(mesh)
+    sceneRegistry.nodes.set(node.id, mesh)
+
+    const { scene, animations } = prepareSceneForExport(root, {
+      [node.id]: node as unknown as AnyNode,
+    })
+
+    expect(animations).toHaveLength(1)
+    for (let index = 0; index < 4; index++) {
+      const panel = scene.getObjectByName(`door-fold-${index}`)
+      expect(panel).toBeDefined()
+      // Rest quaternion must be identity — no residual π on any axis.
+      expect(panel!.quaternion.angleTo(new THREE.Quaternion())).toBeLessThan(1e-4)
+    }
+  })
 })

packages/viewer/src/systems/door/door-system.tsx

@@ -1392,7 +1392,7 @@ export function poseDoorMovingParts(
       // the group rotates about its own origin (see the closed build below).
       const angle = (Math.PI / 2) * t
       const hingeY = leafCenterY + leafHeight / 2
-      group.rotation.x = -angle
+      group.rotation.set(-angle, 0, 0)
       group.position.set(0, hingeY * (1 - Math.cos(angle)), Math.sin(angle) * (hingeY - leafHeight))
       return true
     }
@@ -1410,7 +1410,11 @@ export function poseDoorMovingParts(
         const direction = index % 2 === 0 ? -1 : 1
         if (group) {
           posed = true
-          group.rotation.y = (prevDirection - direction) * foldAngle
+          // Set the full triple (not just `.y`): when the export clones and
+          // decomposes the door matrix, a |Y| > π/2 rotation re-derives into a
+          // gimbal-flipped euler (x=z=π). Assigning only `.y` would leave that
+          // π residue on x/z and bake a flipped rest pose.
+          group.rotation.set(0, (prevDirection - direction) * foldAngle, 0)
         }
         prevDirection = direction
       }
@@ -1446,7 +1450,7 @@ export function poseDoorMovingParts(
           z = -(curveRadius + pathPosition - curveLength)
         }
         group.position.set(0, y, z)
-        group.rotation.x = rotationX
+        group.rotation.set(rotationX, 0, 0)
       }
       return posed
     }