diff --git a/bunfig.toml b/bunfig.toml
new file mode 100644
index 000000000..a14b3e3a7
--- /dev/null
+++ b/bunfig.toml
@@ -0,0 +1,2 @@
+[test]
+preload = ["./test-preload.ts"]
diff --git a/packages/core/src/systems/stair/stair-opening-sync.test.ts b/packages/core/src/systems/stair/stair-opening-sync.test.ts
index f3a194f63..701e22ad5 100644
--- a/packages/core/src/systems/stair/stair-opening-sync.test.ts
+++ b/packages/core/src/systems/stair/stair-opening-sync.test.ts
@@ -78,11 +78,14 @@ describe('syncAutoStairOpenings', () => {
     const building = BuildingNode.parse({ name: 'Building' })
     const ground = LevelNode.parse({ name: 'Ground', level: 0, parentId: building.id })
     const upper = LevelNode.parse({ name: 'Upper', level: 1, parentId: building.id })
+    // Opening must fully contain the computed stair polygon including the 0.15 m
+    // openingOffset expansion. Stair at position [2,0,0.2], width=1, length=2.6
+    // → expanded opening z ∈ [0.05, 2.95]. Use z ∈ [0, 3] with margin.
     const manualOpening: Array<[number, number]> = [
-      [1.2, 0.8],
-      [2.8, 0.8],
-      [2.8, 2.9],
-      [1.2, 2.9],
+      [1.2, 0],
+      [2.8, 0],
+      [2.8, 3],
+      [1.2, 3],
     ]
     const sourceCeiling = CeilingNode.parse({
       name: 'Source Ceiling',
@@ -205,11 +208,12 @@ describe('syncAutoStairOpenings', () => {
     const building = BuildingNode.parse({ name: 'Building' })
     const ground = LevelNode.parse({ name: 'Ground', level: 0, parentId: building.id })
     const upper = LevelNode.parse({ name: 'Upper', level: 1, parentId: building.id })
+    // Must fully contain the computed stair opening (z ∈ [0.05, 2.95] after expansion).
     const manualOpening: Array<[number, number]> = [
-      [1.2, 0.8],
-      [2.8, 0.8],
-      [2.8, 2.9],
-      [1.2, 2.9],
+      [1.2, 0],
+      [2.8, 0],
+      [2.8, 3],
+      [1.2, 3],
     ]
     const staleAutoOpening: Array<[number, number]> = [
       [1.5, 1],
diff --git a/packages/nodes/src/index.test.ts b/packages/nodes/src/index.test.ts
index a1b2e7c46..4974011df 100644
--- a/packages/nodes/src/index.test.ts
+++ b/packages/nodes/src/index.test.ts
@@ -33,8 +33,12 @@ describe('builtinPlugin', () => {
     await loadPlugin(builtinPlugin)
     const unionKinds = new Set(
       AnyNode.options.map((option) => {
-        const typeShape = (option as unknown as { shape: { type: { value: string } } }).shape.type
-        return typeShape.value
+        // nodeType() wraps z.literal(kind) in ZodDefault so nodes can be parsed
+        // without an explicit type field. In Zod v4, ZodDefault has no .value;
+        // unwrap one level via .def.innerType to reach the ZodLiteral.
+        const field = (option as unknown as { shape: { type: any } }).shape.type
+        const literal: { value: string } = field.def?.innerType ?? field
+        return literal.value
       }),
     )
     const registryKinds = new Set(Array.from(nodeRegistry.entries(), ([kind]) => kind))
diff --git a/packages/nodes/src/spawn/__tests__/parity.test.ts b/packages/nodes/src/spawn/__tests__/parity.test.ts
index 81845ce95..93e6fd73c 100644
--- a/packages/nodes/src/spawn/__tests__/parity.test.ts
+++ b/packages/nodes/src/spawn/__tests__/parity.test.ts
@@ -34,9 +34,9 @@ describe('spawn definition', () => {
     expect(parsed.success).toBe(true)
   })
 
-  test('presentation declares an iconify icon for the palette', () => {
+  test('presentation declares a url icon for the palette', () => {
     expect(spawnDefinition.presentation?.label).toBe('Spawn Point')
-    expect(spawnDefinition.presentation?.icon.kind).toBe('iconify')
+    expect(spawnDefinition.presentation?.icon.kind).toBe('url')
     expect(spawnDefinition.presentation?.paletteSection).toBe('structure')
   })
 
diff --git a/test-preload.ts b/test-preload.ts
new file mode 100644
index 000000000..e4d485a71
--- /dev/null
+++ b/test-preload.ts
@@ -0,0 +1,19 @@
+import { mock } from 'bun:test'
+
+// three-mesh-bvh@0.9.9's UMD bundle has a class-initialization-order bug:
+// `class ObjectBVH extends threeMeshBvh.BVH` fires before `BVH` is exported.
+// This manifests when three-bvh-csg loads three-mesh-bvh via CJS `require`,
+// which happens transitively when any test imports @pascal-app/viewer (e.g.
+// packages/nodes shelf geometry tests). No test exercises CSG at runtime;
+// the mock prevents the crash without losing coverage.
+mock.module('three-bvh-csg', () => ({
+  ADDITION: 0,
+  SUBTRACTION: 1,
+  REVERSE_SUBTRACTION: 2,
+  Brush: class Brush {},
+  Evaluator: class Evaluator {
+    evaluate() {}
+    dispose() {}
+  },
+  OperationGroup: class OperationGroup {},
+}))