diff --git a/package.json b/package.json
index 9a0c91b8d..e827ece0d 100644
--- a/package.json
+++ b/package.json
@@ -15,7 +15,8 @@
     "test": "playwright test --project=openpencil",
     "test:update": "playwright test --project=openpencil --update-snapshots",
     "test:figma": "playwright test --project=figma",
-    "figma:debug": "open -a Figma --args --remote-debugging-port=9222"
+    "figma:debug": "open -a Figma --args --remote-debugging-port=9222",
+    "test:unit": "bun test ./tests/engine"
   },
   "dependencies": {
     "@tailwindcss/vite": "^4.2.1",
diff --git a/tests/engine/scene-graph.test.ts b/tests/engine/scene-graph.test.ts
new file mode 100644
index 000000000..f6596a8cf
--- /dev/null
+++ b/tests/engine/scene-graph.test.ts
@@ -0,0 +1,53 @@
+import { describe, test, expect } from 'bun:test'
+
+import { SceneGraph } from '../../src/engine/scene-graph'
+
+function rect(graph: SceneGraph, name: string, x = 0, y = 0, w = 50, h = 50) {
+  return graph.createNode('RECTANGLE', graph.rootId, { name, x, y, width: w, height: h }).id
+}
+
+describe('SceneGraph', () => {
+  test('create rectangle', () => {
+    const graph = new SceneGraph()
+    const id = rect(graph, 'Rect', 100, 100, 200, 150)
+    const node = graph.getNode(id)!
+    expect(node.type).toBe('RECTANGLE')
+    expect(node.x).toBe(100)
+    expect(node.width).toBe(200)
+  })
+
+  test('create and delete', () => {
+    const graph = new SceneGraph()
+    const id = rect(graph, 'R')
+    expect(graph.getNode(id)).toBeTruthy()
+    graph.deleteNode(id)
+    expect(graph.getNode(id)).toBeFalsy()
+  })
+
+  test('reparent into frame', () => {
+    const graph = new SceneGraph()
+    const frame = graph.createNode('FRAME', graph.rootId, { name: 'F', x: 50, y: 50, width: 400, height: 400 }).id
+    const r = rect(graph, 'R', 100, 100)
+    graph.reparentNode(r, frame)
+    const children = graph.getChildren(frame)
+    expect(children.map(c => c.id)).toContain(r)
+  })
+
+  test('children order', () => {
+    const graph = new SceneGraph()
+    rect(graph, 'A')
+    rect(graph, 'B')
+    rect(graph, 'C')
+    const names = graph.getChildren(graph.rootId).map(n => n.name)
+    expect(names).toEqual(['A', 'B', 'C'])
+  })
+
+  test('update node', () => {
+    const graph = new SceneGraph()
+    const id = rect(graph, 'R')
+    graph.updateNode(id, { x: 200, name: 'Updated' })
+    const node = graph.getNode(id)!
+    expect(node.x).toBe(200)
+    expect(node.name).toBe('Updated')
+  })
+})