Code researcher "pdfu" has uncovered private frameworks in iOS 27 and macOS Golden Gate revealing Apple designed Siri's new architecture to work deeply with third-party AI models. One mechanism, Model Delegation, allows Claude to appear as a Siri extension similar to the existing ChatGPT extension. In a video shared on X, a macOS user selects Claude via an "Ask..." contextual menu, asks Siri to "Ask Claude" to set a reminder, and Claude interprets the request before Siri creates it in the Reminders app. Another example shows Claude generating a CSV file — a task Siri cannot handle natively.

A second, more profound protocol in "Model Manager Services" appears to allow Apple's server-side Siri model to be completely replaced by another model like GPT-5.6. In this scenario, ChatGPT receives Apple's Siri planner prompt and tool definitions, enabling it to request system actions, access personal data, and formulate answers presented through Siri's interface and voice. A demo shows ChatGPT finding emails, summarizing them, and sending a Messages reply, with the interaction logged in OpenAI's platform.

The EU's Digital Markets Act likely influenced this approach, requiring Apple to grant third parties effective access to iOS features available to its own services, explicitly including Siri. Currently, the "Ask..." implementation is limited to ChatGPT in the macOS 27 Golden Gate Release Candidate, and model delegation entitlements aren't yet open to third parties or front-facing to users, but the code shows extensive engineering for future model interoperability.