Code detective “pdfu” has discovered private iOS 27 and macOS Golden Gate frameworks that show Apple designed its new Siri architecture to work with third-party AI models at what appears to be a surprisingly deep level.
A mechanism called model delegation allows Claude to appear as a Siri extension in the same way as the existing built-in ChatGPT extension. In the PDF video, shared on
After enabling the Claude extension, the user asks Siri to “Ask Claude” to set a reminder in Apple’s Reminders app. Claude then interprets the callback request into natural language and Siri then creates the reminder. The implication is that if the request requires access to an Apple system feature, Claude refers the task to Siri.
In another example, Claude can be seen in a Siri app chat window receiving a request to create a CSV file – something Siri itself can’t handle – and successfully returning the result.
What’s more intriguing is the second protocol demonstrated in the video which appears to go considerably further and could actually open up the AI landscape to Apple software demands.
An inference provider in “Model Manager Services” apparently allows Apple’s server-side Siri model to be completely replaced with another model, such as GPT-5.6. In this scenario, ChatGPT receives Apple’s Siri Scheduler prompt and tool definitions, allowing it to request system actions, receive the resulting personal data, and formulate a response that Siri presents using its own interface and voice.
And here is an application extension replacing the server model of Siri AI with GPT-5.6 Terra. It uses the inference delivery protocol in Model Manager Services. GPT-5.6 receives Apple’s native Siri scheduler prompt and tool definitions. It can make calls to tools that perform system actions, and… pic.twitter.com/cz88kyq3io
– pdfu (@itspdfu) September 13, 2026
In the demo video, the user asks the ChatGPT model (within the Siri app) to search for emails on a specific topic, summarize their content and action points, and then send a message to a person in the user’s contacts via the Messages app. The response is then displayed as saved in the OpenAI platform web interface.
The European Union’s Digital Markets Act may have helped shape Apple’s approach in this area, because it requires Apple to give third parties effective access to iOS hardware and software features available for Apple’s own services, and the European Commission has specifically stated that this principle extends to Siri.
The “Ask…” implementation is currently limited to the ChatGPT extension in the macOS 27 Golden Gate Release Candidate (which is actually the final version of the software that will be released later today), so Claude is not yet available. Meanwhile, Apple has not yet opened the right of model delegation to third parties and it is not aimed directly at users, but it at least shows how well Apple has designed Siri for future model interoperability.
