Add a new note or todo item to the store. Use this whenever the user wants to remember something, jot down a task, or create a todo.

List all saved notes/todos. Optionally filter to only show items that are still open (not done) or only completed ones.

Search notes by a keyword. Returns any note whose text contains the query (case-insensitive).

Mark a note/todo as done, by its id.

Permanently delete a note/todo by its id.