Siri in iOS 27 Can Be Swapped Out for Claude or ChatGPT — Found in the Code

A code researcher going by the handle pdfu dug into the private frameworks of iOS 27 and macOS Golden Gate and discovered that Apple designed Siri's new architecture from the outset to work with third-party AI models — and at a surprisingly deep level, at that.

Model Delegation

The first mechanism, called Model Delegation, lets Claude act as a Siri extension — much as it already works with the built-in ChatGPT extension. In a clip pdfu posted on X, a macOS user invokes the “Search or Ask” bar and, through the “Ask...” context menu, selects Claude as the model. After activating the extension, they ask Siri to “ask Claude” to create a reminder: Claude parses the natural-language request, while the reminder itself is created in the app by Siri. The logic is this: if a task requires access to an Apple system function, Claude hands it back to the assistant. In another example, Claude — in the Siri dialog window — is asked to make a CSV file, something Siri itself can't do, and pulls it off successfully.

A Full “Brain” Swap

The second protocol looks far more radical. The inference provider mechanism in Model Manager Services appears to allow Siri's server-side model to be replaced wholesale with someone else's — GPT-5.6, for instance. In this scenario, ChatGPT receives Siri's prompt planner and tool descriptions from Apple, which means it can request system actions, obtain the user's personal data, and formulate a response that Siri then delivers through its own interface and in its own voice.

In the demonstration, the user asks the ChatGPT model (inside the Siri app) to find emails on a given topic, summarize their content and action items, and then send a message to a contact via Messages. Tellingly, the request is subsequently visible in the logs on OpenAI's web platform.

Where Europe Comes In

Apple's approach was likely shaped by the European Digital Markets Act: it requires giving third-party developers effective access to the same iOS hardware and software capabilities available to the company's own services, and the European Commission explicitly stated that this principle extends to Siri as well.

For now, all of this remains groundwork for the future. In the final build of macOS Golden Gate (the Release Candidate, effectively the release), the “Ask...” implementation is limited to the ChatGPT extension — Claude isn't available yet. Apple has not yet opened up model delegation rights to third-party developers, and the mechanism hasn't been surfaced for users. But the code clearly shows just how thoroughly Siri has already been prepared for future compatibility with any model.

Source: Hacker News