Apple's OS 27 releases expand Continuity beyond simple handoffs by synchronizing Siri conversations and live Mac content across supported devices. The dedicated Siri app now privately syncs conversation history through iCloud across iPhone, iPad, Mac, Apple Watch, and Vision Pro, allowing users to begin a request on one device and continue on another without repeating context.

Spatial Preview connects macOS 27 and visionOS 27 by letting Mac apps send documents, spatial images, PDFs, or 3D assets to Quick Look on nearby Vision Pro units. The headset renders content through its spatial interface while the Mac remains the authoring computer, updating previews in real time as edits occur.

Continuity functions as a policy layer rather than a single protocol. Bluetooth Low Energy handles device discovery, direct Wi-Fi carries larger payloads, and iCloud provides persistence when proximity isn't needed. Features like Handoff, AirDrop, Sidecar, and Mac Virtual Display rely on various combinations of these transports based on data size, distance, and access requirements.

An Apple Account establishes ownership, while proximity and authentication determine which devices can participate. Private Cloud Compute supports some Siri requests, with iCloud and local trust systems handling other aspects of the cross-device experience.