Fix the following issue:
Unified node CRUD on the folder-tree service
The folder-tree service holds the explorer's file/folder hierarchy in its state under
folderTree.data. That value is a list of root-folder nodes; every node may carry a
children list of nested nodes, and each node has a numeric id, a name, and a
fileType of File, Folder, or RootFolder.
Right now there is no convenient, general-purpose way to look up or mutate an arbitrary node in that hierarchy — callers have to reach for several narrow helpers and reimplement tree traversal themselves. Add a small, unified set of node operations to the service so that consumers can manage the tree through one consistent API:
get — given a node id, return the matching node from anywhere in the hierarchy (any root, at any depth). Return
nullwhen no node has that id.add — insert a new node.
- When given a reference id that points to a folder (a
FolderorRootFolder), the new node becomes a child of that folder. - When given a reference id that points to a file, the new node is placed alongside it, inside the same parent folder.
- When called without a reference id, the new node is added as a new top-level root entry (appended after any existing roots).
- When given a reference id that points to a folder (a
update — given a node carrying an
idplus any fields to change, merge those fields into the existing node in place, leaving the node's other fields and its position in the tree untouched. Do nothing if no node has that id.remove — given a node id, delete that node (and its entire subtree) from the hierarchy. Sibling nodes are unaffected. Do nothing if no node has that id.
After any of add, update, or remove, the change must be reflected in the service's
state, so a subsequent get (and reading folderTree.data) observes it.
These operations work across a hierarchy that may contain multiple root folders and arbitrarily nested children.