= UseCase04 - Saves a Listing
** Initiating actor: Client **
== Description
A client browses listings and can save a listing into their favourites for quick access later. When the client clicks “Save” on a listing, the system verifies the client is logged in, verifies the listing exists, then stores the favourite record. The client can later view or remove saved listings.
== Scenario
1. Client clicks a listing from the lisiting page.
{{{
SELECT
  l.listing_id,
  l.status,
  l.price,
  l.description,
  l.created_at,
  a.animal_id,
  a.name AS animal_name,
  a.species,
  a.breed,
  a.located_name,
  l.owner_id
FROM listings l
JOIN animals a ON a.animal_id = l.animal_id
WHERE l.listing_id = $1;

}}}
2. Client clicks "Save Listing".
3. The system saves the listing to favorites to the client.
{{{
INSERT INTO favourite_listings (user_id, listing_id)
VALUES ($1, $2);
}}}