Function buildTree

packages/app-core/src/components/Sidebar.tsx:3772–3851

(
  notes: NoteMeta[],
  assets: AssetMeta[],
  topFolder: NoteFolder,
  folders: FolderEntry[],
  vaultSettings: ReturnType<typeof useStore.getState>["vaultSettings"],
)

}

function buildTree(
  notes: NoteMeta[],
  assets: AssetMeta[],
  topFolder: NoteFolder,
  folders: FolderEntry[],
  vaultSettings: ReturnType<typeof useStore.getState>["vaultSettings"],
): TreeNode {
  const root: TreeNode = {
    name: topFolder,
    subpath: "",
    siblingOrder: -1,
    notes: [],
    assets: [],
    children: [],
  };
  const byPath = new Map<string, TreeNode>();
  byPath.set("", root);
  const folderOrder = new Map(
    folders.map((folder) => [folder.subpath, folder.siblingOrder] as const),
  );
  const symlinkBySubpath = new Map(
    folders.map((folder) => [folder.subpath, folder.isSymlink ?? false] as const),
  );

  const ensureFolder = (subpath: string): TreeNode => {
    const existing = byPath.get(subpath);
    if (existing) return existing;
    const segments = subpath.split("/");
    let parent = root;
    let acc = "";
    for (const seg of segments) {
      acc = acc ? `${acc}/${seg}` : seg;
      let node = byPath.get(acc);
      if (!node) {
        node = {
          name: seg,
          subpath: acc,
          siblingOrder: folderOrder.get(acc) ?? Number.MAX_SAFE_INTEGER,
          notes: [],
          assets: [],
          children: [],
          isSymlink: symlinkBySubpath.get(acc) ?? false,
        };
        byPath.set(acc, node);
        parent.children.push(node);
      }
      parent = node;
    }
    return parent;
  };

  // First pass: create nodes for every folder on disk (this is what
  // keeps empty folders visible in the tree).
  for (const f of folders) {
    if (!f.subpath) continue;
    ensureFolder(f.subpath);
  }