Running ChatGPT with Siri always felt like duct tape. Siri hands your question off, a browser tab opens, and the moment is gone. iOS 27 quietly changes that, and hidden code shows Apple is going much further than anyone announced.
Apple built Siri to run on other AI models
iOS 27 and macOS 27 Golden Gate shipped on September 14. Within hours, a code sleuth who goes by pdfu found private frameworks inside both that Apple never mentioned. They show the new Siri architecture was designed to work with third-party models at a surprisingly deep level.
This is not the old “hand off to ChatGPT” trick, either. Apple built two separate mechanisms into the system. One lets a model like Claude appear as a Siri extension. The other goes further: it can replace Apple’s own server-side Siri model completely.
Context matters here. Apple rebuilt Siri from scratch this year, as we covered in our guide to Siri AI. What the new code adds is choice. You could pick the brain, and Siri stays the hands and the voice.
Why would Apple allow this at all? Partly because regulators are forcing the issue. The EU’s Digital Markets Act requires Apple to give third parties the same access to iPhone features that Apple gives itself, and the European Commission has already said that principle extends to Siri.
The two ways a model can replace Siri
Here’s the difference between the two mechanisms, because the details matter for how you’d actually use them.
| Mechanism | What it does | Status today |
|---|---|---|
| Model Delegation (Siri extension) | Claude or ChatGPT shows up in Siri’s “Ask…” menu, answers inside the Siri app, and hands anything system-related back to Siri | “Ask ChatGPT” is live on Mac. Claude is not available yet |
| Inference Provider (full model swap) | The third-party model receives Apple’s Siri planner prompt and tool definitions, does the entire job, and Siri just speaks the answer | Not user-facing anywhere yet. Demonstrated working in code |
In plain English: the first one adds a menu option. The second one swaps out Siri’s brain and keeps the face. Both were demonstrated on a Mac, and both come straight from Apple’s own frameworks, not from a rumor mill.
What you can already do today
You don’t have to wait for Claude. If you’ve ever wanted ChatGPT with Siri as the front end instead of a browser tab, today is the day. The ChatGPT extension is live and user-facing on Macs running macOS 27, and an older version of the same integration has existed on iPhone since iOS 18.2.
Turn on the ChatGPT extension on your Mac
- Update to macOS 27 Golden Gate (System Settings, then General, then Software Update).
- Open the “Search or Ask” bar, the same spot where you’d normally summon Siri.
- Look for the “Ask…” contextual menu and pick ChatGPT.
- Sign in to your ChatGPT account when prompted. A free account works, though usage is limited. ChatGPT Plus costs $20 a month if you want more headroom.
- Ask something big. “Summarize this document and draft a reply” is a good test. The answer lands right inside the Siri window.
That’s ChatGPT with Siri working as intended: your voice, its brain. Try it on the tasks you’d normally type into a browser. Meeting notes you need trimmed. A rant from a client you need turned into a polite reply. A price comparison across three tabs you were about to open anyway.
Plus, ChatGPT’s desktop reach goes beyond the Ask menu. On Mac, it can now reply to your iMessages too, which we broke down in our ChatGPT iMessages guide.
Set up ChatGPT in Siri on iPhone
iPhone users get the older but still useful version of this. iOS 27 carries the ChatGPT extension that hands complex questions to ChatGPT automatically.
- Open Settings and tap Apple Intelligence & Siri.
- Look for the ChatGPT entry (or Extensions, depending on your build) and tap Set Up.
- Link a ChatGPT account if you want higher limits, or skip it and stay on the free tier.
- From now on, when a question outgrows Siri, it goes to ChatGPT without opening anything.
In practice, the handoff feels small. You ask something like “plan a weekend trip around a concert and my budget,” and instead of a web results card, you get an actual plan. Either way, you keep Siri’s voice and interface. The smarter model just sits underneath.
What happens when Claude joins the menu
Claude’s demo is where things get interesting. In the leaked videos, pdfu enables a Claude extension through the Model Delegation API in App Intents. Claude then shows up in the same Ask menu, prefixed with its name, looking exactly like the new Siri interface.
Two demos are worth noting. First: “Ask Claude to remind me to call the plumber.” Claude reads the request, then hands the task to Siri, which creates the reminder in the Reminders app. Second: Claude produces an actual CSV file, something Siri itself cannot do. The model fills Siri’s gaps instead of fighting them.
None of this is available to regular users yet. Apple hasn’t opened the model delegation entitlement to third-party developers, and there’s no announced timeline. Until then, ChatGPT with Siri remains the only officially enabled combo. Still, the plumbing is built, it demonstrably works, and Anthropic’s Claude page gives you a good sense of what a Claude Siri extension could eventually add to a phone assistant.
For beginners, this is genuinely good news. No new hardware. No separate app to juggle. When the option lands, you pick Claude from a menu the same way you pick ChatGPT today, and your existing Claude subscription (or the free tier) carries over.
The privacy trade-off nobody should skip
The full model swap is the part to think about. In the demonstration, a ChatGPT model called GPT-5.6 Terra receives Apple’s native Siri planner prompt and tool definitions. It can then request system actions, read the personal data that comes back, and act on it. In the video, that meant finding emails on a topic, summarizing them, and sending a message to a contact through the Messages app.
Every one of those requests ran through OpenAI’s platform, where the activity showed up in a web log. As a result, using ChatGPT with Siri this way is a different privacy situation than the current extension. Your assistant’s reasoning, plus chunks of your personal context, now live on someone else’s servers.
That doesn’t make it a deal breaker. It makes it a decision. Before enabling any AI extension, ask three things: what data does this thing see, where does it go, and can I turn it off? If you’re the kind of person who already redacts files before uploading them to a chatbot, apply the same instinct here. Convenience is real, but so is the trail.
What this means for you
The realistic near future looks like this: Siri keeps the face, and you pick the brain. ChatGPT with Siri works today on Mac, in limited form on iPhone, and the code says Claude and full model swaps are next. Apple is clearly wiring AI through its entire lineup, from Apple Watch AI features to the desktop.
So here’s your move: update to macOS 27, flip on the ChatGPT extension in the Ask menu, and hand it one real task today. When Claude appears in that menu, you’ll already know exactly how to use it. The full story lives at MacRumors, and you can start with ChatGPT itself.
