feat: add document history transactions

tests/facade.test.ts

@@ -59,3 +59,15 @@ test('command events carry a document-scoped request context', () => {
   assert.ok(events.includes('command.completed'))
   assert.match(requestId, /^req-/)
 })
+
+test('document mutations use the facade history boundary', () => {
+  const facade = createMockFacade()
+  facade.gui.command.execute({ commandId: 'new-document' })
+  assert.equal(facade.app.document.getActive().label, 'Untitled document')
+  assert.equal(facade.history.canUndo(), true)
+  facade.history.undo()
+  assert.equal(facade.app.document.getActive().label, 'Pump Housing')
+  assert.equal(facade.history.canRedo(), true)
+  facade.history.redo()
+  assert.equal(facade.app.document.getActive().label, 'Untitled document')
+})