my-tree/
├── manifest.ts          # Registers repository and tree
├── tree.repository.ts   # Repository + inline data source
└── types.ts             # Type definitions (optional)

// CORRECT - hideTreeRoot on menuItem
{
  type: 'menuItem',
  kind: 'tree',
  alias: 'My.MenuItem.Tree',
  meta: {
    treeAlias: 'My.Tree',
    menus: ['My.Menu'],
    hideTreeRoot: true,  // Shows items at root level
  },
}

// WRONG - hideTreeRoot on tree (has no effect)
{
  type: 'tree',
  meta: {
    hideTreeRoot: true,  // This does nothing!
  },
}

export const manifests: UmbExtensionManifest[] = [
  // Repository
  {
    type: 'repository',
    alias: 'My.Tree.Repository',
    name: 'My Tree Repository',
    api: () => import('./tree.repository.js'),
  },
  // Tree
  {
    type: 'tree',
    kind: 'default',
    alias: 'My.Tree',
    name: 'My Tree',
    meta: {
      repositoryAlias: 'My.Tree.Repository',
    },
  },
  // Tree Items - use kind: 'default' when workspaces exist
  {
    type: 'treeItem',
    kind: 'default',
    alias: 'My.TreeItem',
    name: 'My Tree Item',
    forEntityTypes: ['my-entity'],
  },
  // MenuItem - hideTreeRoot here
  {
    type: 'menuItem',
    kind: 'tree',
    alias: 'My.MenuItem.Tree',
    meta: {
      treeAlias: 'My.Tree',
      menus: ['My.Menu'],
      hideTreeRoot: true,
    },
  },
];

import { UmbTreeRepositoryBase, UmbTreeServerDataSourceBase } from '@umbraco-cms/backoffice/tree';
import type { UmbControllerHost } from '@umbraco-cms/backoffice/controller-api';
import type { UmbApi } from '@umbraco-cms/backoffice/extension-api';
import type { MyTreeItemModel, MyTreeRootModel } from './types.js';
import { MY_ROOT_ENTITY_TYPE, MY_ENTITY_TYPE } from './entity.js';

// Data source as simple class using helper base
class MyTreeDataSource extends UmbTreeServerDataSourceBase<any, MyTreeItemModel> {
  constructor(host: UmbControllerHost) {
    super(host, {
      getRootItems: async (args) => {
        // Fetch from API or return mock data
        const items: MyTreeItemModel[] = [
          {
            unique: 'item-1',
            parent: { unique: null, entityType: MY_ROOT_ENTITY_TYPE },
            entityType: MY_ENTITY_TYPE,
            name: 'Item 1',
            hasChildren: false,
            isFolder: false,
            icon: 'icon-document',
          },
        ];
        return { data: { items, total: items.length } };
      },
      getChildrenOf: async (args) => {
        // Return children for parent
        return { data: { items: [], total: 0 } };
      },
      getAncestorsOf: async (args) => {
        // Return ancestor path
        return { data: [] };
      },
      mapper: (item: any) => item, // Identity mapper for this example
    });
  }
}

// Repository
export class MyTreeRepository
  extends UmbTreeRepositoryBase<MyTreeItemModel, MyTreeRootModel>
  implements UmbApi
{
  constructor(host: UmbControllerHost) {
    super(host, MyTreeDataSource);
  }

  async requestTreeRoot() {
    const data: MyTreeRootModel = {
      unique: null,
      entityType: MY_ROOT_ENTITY_TYPE,
      name: 'My Tree',
      hasChildren: true,
      isFolder: true,
    };
    return { data };
  }
}

export { MyTreeRepository as api };