Fuente: WIPO "tomato" An online system receives a request from a client device associated with a user to place an order and retrieves user data including a constraint associated with the user. Upon receiving a notification that an item included in the order is not available at a source location, the system generates a prompt including item data for the item, a description of the constraint, contextual information associated with the order, and a request to identify a replacement for the item based on information describing a set of candidate replacement items available at the source location, the item data, the constraint, and the contextual information. The system provides the prompt to a large language model to obtain an output and extracts information describing the replacement from the output. The system generates a message including a suggestion to replace the item with the replacement and sends the message to the client device.