Image: MacRumors Code in iOS 27 Shows Siri Can Run on Claude or ChatGPT Instead of Apple's Own Model
A code researcher found private frameworks in iOS 27 and macOS 27 that let third-party models plug into Siri — either as an extension or as a full replacement for Apple's own model. None of it is switched on yet.
A code researcher digging through Apple's latest betas has found the clearest evidence yet that the new Siri was designed to be model-agnostic — with hooks that let third-party AI models like Claude or ChatGPT take over parts of the assistant, or all of it.
The findings come from a developer who goes by "pdfu," who posted a video on X on September 13 showing two separate mechanisms in private frameworks inside iOS 27 and the macOS 27 (Golden Gate) release candidate. MacRumors reported the details on Monday morning.
The first is a Model Delegation API in App Intents. It lets a third-party model appear as a Siri extension in the "Ask…" menu — the same slot Apple's built-in ChatGPT extension already occupies. In the demo, a Mac user opens the "Search or Ask" bar, picks Claude from the menu, and asks Claude to set a reminder in Apple's Reminders app. Claude parses the natural-language request, then hands the actual system task back to Siri. In another clip, Claude sits inside a Siri conversation window and successfully generates a CSV file — something Siri itself can't do.
The second mechanism goes further. An Inference Provider protocol inside "Model Manager Services" lets an outside model replace Apple's server-side Siri model outright. The demo swaps in GPT-5.6 Terra: the third-party model receives Apple's Siri planner prompt and tool definitions, so it can request system actions, receive the resulting personal data, and write the answer that Siri delivers in its own interface and voice. Per AI Weekly's write-up, a model plugged in this way gets the same system access as Apple's Private Cloud Compute — including the ability to request user data and make tool calls that change System Settings.
The catch: none of this is user-facing. The "Ask…" menu currently lists only Apple's built-in ChatGPT extension, and Apple has not opened the delegation entitlement to any outside developer. As 9to5Mac put it, "you cannot yet activate this — it's visible in the code but not currently enabled."
Context matters here. In January, Apple announced that the rebuilt Siri would run on a Google Gemini-based model, and in May, Bloomberg reported that iOS 27 would add an "Extensions" feature letting users choose third-party AI services across Apple Intelligence — Writing Tools, Image Playground, Siri — with third-party voices so you can tell which model is answering. Today's find suggests the plumbing underneath is even deeper than those reports implied: not just routing queries to a chatbot, but replacing the model that plans and executes.
9to5Mac speculates the feature could end up limited to the EU, where Apple has already made similar accommodations under regulatory pressure — that part is their reading, not something in the code. What's in the code is a Siri architecture that treats the model as a replaceable part. Whether Apple ever lets you choose the part is still an open question.
Sources: MacRumors, 9to5Mac, AI Weekly. The story sat on Hacker News' front page Monday morning.