fix: bootstrap empty Pascal scenes for agents

services/pascal-editor/packages/mcp/src/tools/scene-lifecycle/load-scene.test.ts

@@ -60,6 +60,24 @@ describe('load_scene', () => {
     expect(result.isError).toBe(true)
   })
 
+  test('bootstraps an editable default hierarchy for an empty stored scene', async () => {
+    await store.save({
+      id: 'empty-scene',
+      name: 'Empty',
+      graph: { nodes: {}, rootNodeIds: [] },
+    })
+
+    const result = await client.callTool({
+      name: 'load_scene',
+      arguments: { id: 'empty-scene' },
+    })
+
+    expect(result.isError).toBeFalsy()
+    expect(bridge.getRootNodeIds().length).toBeGreaterThan(0)
+    expect(Object.keys(bridge.getNodes()).length).toBeGreaterThan(0)
+    expect(bridge.findNodes({ type: 'level' }).length).toBeGreaterThan(0)
+  })
+
   test('rejects empty id per schema', async () => {
     const result = await client.callTool({
       name: 'load_scene',

services/pascal-editor/packages/mcp/src/tools/scene-lifecycle/load-scene.ts

@@ -45,7 +45,12 @@ export function registerLoadScene(server: McpServer, bridge: SceneOperations): v
         throwMcpError(ErrorCode.InvalidParams, 'scene_not_found', { id })
       }
       try {
-        bridge.loadJSON(result.graph)
+        if (Object.keys(result.graph.nodes ?? {}).length === 0) {
+          bridge.setScene({}, [])
+          bridge.loadDefault()
+        } else {
+          bridge.loadJSON(result.graph)
+        }
         bridge.setActiveScene(result)
       } catch (err) {
         const msg = err instanceof Error ? err.message : String(err)