Verification of items placed in physical shopping cart

A computer system comprising:

• one or more data processing apparatuses including one or more processors, memory, and storage devices storing instructions that, when executed, cause the one or more processors to perform operations comprising:
• scanning an item, by a mobile computing device;
• in response to scanning the item, providing, by the mobile computing device to a server system over a wireless network, a request for item verification data for verifying the item scanned by the mobile computing device, wherein the request for item verification data comprises an item identifier of the item scanned by the mobile computing device;
• receiving, by the mobile computing device from the server system over the wireless network, the item verification data for verifying the item scanned by the mobile computing device, wherein the item verification data comprises item verification data corresponding to each of one or more item sensors of a shopping cart that is separate from the mobile computing device;
• receiving, by the mobile computing device and from a cart computing system of the shopping cart that is separate from the mobile computing device, over a local wireless connection between the mobile computing device and the cart computing system of the shopping cart, sensor data that is collected by one or more item sensors of the shopping cart as a result of the item having been placed in the shopping cart;
• performing, by the mobile computing device, a verification of the item based on the sensor data and the item verification data;
• and
• presenting, by the mobile computing device, verification results based on performing the verification of the item.