Apple's Foundation Models framework allows developers to use on-device AI models, and a new package called Claude for Foundation Models enables the use of Claude, a server-side language model, as a drop-in replacement. The package conforms to the Foundation Models protocol, allowing developers to use the same API for both on-device and server-side models. This enables developers to write their app once and use either the on-device model or Claude, depending on their needs. The package is currently in beta and targets the Foundation Models server-side language model API introduced in the OS 27 betas.