# Grow a shelf

> Find books that fit a shelf and aren't in your library yet, kept as a wishlist you review.

**Grow this shelf** suggests books that belong on a shelf and that you don't have. They are kept as a wishlist for you to look through. Nothing is downloaded or bought.

## Grow a shelf

1. Open a shelf note.
2. Select **Grow this shelf** in the Library panel's **Shelf** tab, or right-click the shelf note.
3. A window says how many books will be asked for and what it may cost. Select **Grow**.

How it works:

- A model, through the `library-hub.shelf-grow` role in Model Hub, reads the shelf's name, description and books, and proposes others that fit, each with a reason.
- Each proposal is looked up in **Open Library** (and **Google Books**, if you added a key), about one a second. A book neither catalog knows is dropped, so made-up titles don't reach you. The catalog gives the year and an ISBN.
- Books in your library (by ISBN, or by title and author), and books suggested before, are left out.

The notice says how many joined the wishlist and what was left out, with **Undo**. The wishlist opens.

## The wishlist

The wishlist is in `Books/Wishlist`: one note per book, with its title, author, year, ISBN, the shelf, and why it fits, plus `Wishlist.base`, a table with three views: **To review**, **Wanted** and **Turned down**.

- Set `want: true` on a book to keep it in mind.
- Set `reject: true`, or delete its note. Either way it won't be suggested again.

Change the folder, and how many books one run asks for (15 by default), in **Settings → Library Hub → Shelves**.

## Costs

One model call per run, small next to a summary: the shelf's book titles go in and a short list comes out. Open Library and Google Books are free. See [Privacy and costs](privacy-and-costs.md).

## Related

- [Build shelves](shelves.md)
- [New books](new-books.md)