Siri Can Call Claude, but Apple Still Holds the Keys

Apple shipped iOS 27 and macOS Golden Gate on September 14 with private hooks that let Claude or ChatGPT think for Siri.

The hooks are already in the system. Users cannot turn them on. Siri still speaks, still draws the cards, and still runs the tools that touch Reminders and Settings.

Two Private Hooks Already Sit in the Shipping OS

The person who pulled the wiring into the open is pdfu, a coder and reverse engineer who posts as @itspdfu. On September 13 he showed two private hooks in iOS 27 and macOS Golden Gate. One adds a third-party model as a Siri extension. The other can stand in for Siri AI’s server-side model.

Neither path is a Settings toggle. Both sit behind Apple-controlled entitlements. ChatGPT already rides the first path as Apple’s built-in partner. Claude does not, unless someone sidesteps the lock on a development Mac.

THE TWO SIRI HOOKS IN OS 27

pdfu’s first clip is the consumer version of that table. Claude shows up in Siri’s Ask menu and follows the same flow as the built-in ChatGPT extension.

iOS 27 and macOS Golden Gate have private hooks that let apps add Siri Extensions and replace Siri AI’s server backend with third-party models.

First, here’s Claude running as a Siri Extension using the Model Delegation API in App Intents. Claude can appear in Siri’s “Ask…”… pic.twitter.com/OXKHQ4hDY8

— pdfu (@itspdfu) September 13, 2026

Siri Still Holds the House Keys

In the demo, the Mac’s Search or Ask bar is open. Claude is picked from Ask. The spoken request is to create a reminder. Claude reads the sentence. Siri writes the reminder.

That handoff is the design, not a glitch. A third-party extension is sandboxed. It can interpret a request and even rewrite it. It cannot be the process that opens Reminders. When the job needs a system app, Claude sends the original or a changed request back, and Siri finishes it.

The same demo shows the other side of that split. Siri still cannot produce a CSV. Claude can, and it hands the file back through Siri’s own response stream. pdfu wrote that in some cases Siri Extensions can be more powerful than Siri AI, and the CSV is the clean example: the guest model does a job the host model still fails, then the host keeps the keys to the house.

On July 30 he had already described the same plumbing in a developer thread. His Claude bridge implements Apple’s internal AgentIntent, takes an IntentPrompt, and turns Claude’s text, files, tool calls, and device-action requests back into Apple’s native stream. He could use that extension across Siri AI, Writing Tools, Visual Intelligence, and the Use Model Shortcut action. Image Playground stayed out, because Claude had no native image model to plug in there.

The Deeper Swap Lets GPT-5.6 Call System Tools

The second hook goes further than an Ask menu. It uses the Inference Providing protocol inside Model Manager Services and a private ExtensionKit point, com.apple.modelmanager.inferenceprovider. In pdfu’s second clip, GPT-5.6 Terra stands in for Siri AI’s server model.

GPT-5.6 receives Apple’s native Siri planner prompt and tool definitions. It can make tool calls that perform system actions, and receive tool call results with personal data. Finally, GPT-5.6 can return a response through Siri AI’s UI and voice, including interactive elements.

pdfu, reverse engineer, on X, September 13, 2026

And here’s an app extension replacing Siri AI’s server model with GPT-5.6 Terra. It uses the Inference Providing protocol in Model Manager Services.

GPT-5.6 receives Apple’s native Siri planner prompt and tool definitions. It can make tool calls that perform system actions, and… pic.twitter.com/cz88kyq3io

— pdfu (@itspdfu) September 13, 2026

Watch the end of that clip and the requests show up on OpenAI’s own logs. The “replacement” still speaks with Siri’s voice and still spends Apple’s tool list. It does not open a ChatGPT window. It fills Siri.

pdfu also named a local planner he calls Skimmer, with limited on-device reach, that hands most work to Apple’s server models. That is the actual product shape: a small local router, a heavier cloud brain, and now a private socket where a different cloud brain can sit. Apple has not confirmed any GPT-5.6 arrangement. The name in the demo is pdfu’s, read out of the hook he exercised, not a partnership announcement.

Brussels Asked for This Intermediary in June

The same summer Apple told Europe it could not ship the new assistant on iPhone and iPad. Apple introduced Siri AI in June as a new, Apple Intelligence-powered Siri. The same day, it said the Digital Markets Act blocked that launch on iOS 27 and iPadOS 27 in the EU. Macs and Vision products in the bloc would still get it. Watch would not, because watchOS Siri AI needs a paired iPhone that has it.

We’re deeply disappointed that our EU users won’t have Siri AI on iPhone or iPad when we share our new software releases later this year. Our hope is to eventually bring Siri AI to the EU, and we will continue to engage with EU regulators on a path forward. However, their refusal to engage constructively on solutions that preserve privacy and security means we do not currently have a timeline for Siri AI’s availability on iOS and iPadOS in the EU.

Craig Federighi, senior vice president of Software Engineering, Apple newsroom, June 8, 2026

Apple’s complaint was specific. It said the Commission’s reading of the DMA would force it to give any virtual assistant direct access to private data and the power to control other apps, including reading and sending messages, making purchases, opening files, and acting across apps, without ongoing visibility. Apple’s proposed fix was the Trusted System Agent Apple designed for the EU, an intermediary that would let rival assistants reach the same features Siri AI uses, rolled out over 18 months. The company said the Commission rejected that plan and every other proposal it offered.

HOW THE HOOKS SURFACED

1. June 8, 2026: Apple announces Siri AI, withholds it from EU iPhone and iPad, and describes Trusted System Agent as the rejected middle layer.
2. July 30, 2026: pdfu writes that the Siri Extensions pieces are already in macOS 27 and shows Ask Claude working through Model Delegation.
3. September 13, 2026: He posts the Claude extension demo and the GPT-5.6 Terra backend swap.
4. September 14, 2026: iOS 27 and macOS Golden Gate ship. The user-facing picker stays dark.
5. September 15, 2026: An unofficial Claude provider lands in public source, still requiring a loosened Mac.

Put those dates next to each other and the private hooks look less like a gift to power users and more like the same intermediary argument, built into the shipping OS, with Apple still holding the switch. A later 27.x drop timed with an EU Siri AI launch is a guess some developers are making. Apple has not said that.

Why Claude Still Does Not Appear in Ask

Claude does not appear in Siri’s Ask menu on a normal iOS 27 or Golden Gate install. ChatGPT does, through Apple’s own extension. The Model Delegation API is real and already wired for other providers, but it is locked behind a private entitlement Apple has not given out.

That entitlement is com.apple.developer.model-delegation. It sits on an internal API inside the public App Intents framework. pdfu found Apple’s ChatGPT implementation on disk at /System/Library/ExtensionKit/Extensions/GenerativePartnerPrototypeExtension.appex, which is how he pulled the prompts, tools, and output schemas Apple already sends its current partner. In the unofficial work that followed, the private selectedLLMId, defaultLLM, and intendedDefaultLLM values still resolve to com.apple.openai.chatgpt.

Paying for Claude, Gemini, or Grok does not change that menu. Siri AI still offers Apple’s models and the ChatGPT extension. The missing product is not another chatbot app. It is permission to stand in the same Ask list ChatGPT already occupies.

An Unofficial Claude Bridge Runs on Unlocked Macs

Marcel Pociot published an independent Claude bridge on GitHub after pdfu’s clips, with pdfu contributing to the repo. It is MIT-licensed, experimental, and explicit about what it is not. It is not an Apple product. It is not an Anthropic product. It talks to a signed-in Claude Code command line from a sandboxed provider extension, then streams text back into Siri’s native UI.

WHAT THE UNOFFICIAL CLAUDE BRIDGE REQUIRES

• A loosened Mac: The project needs macOS 27 with System Integrity Protection off and AMFI disabled, and it tells people to use a development machine.
• Private signing: Host and extension carry com.apple.developer.model-delegation and are ad-hoc signed; Apple has not granted a distributable entitlement.
• Text only: The provider does not generate images, take attachments, run device actions, or read Mail, Contacts, Messages, or Siri’s semantic index.
• No proven default: There is no verified system-wide default for this custom extension on the tested build, macOS 27 26A428 with Xcode 27.

Pociot’s README is blunt on that last point. Picking Ask, then Claude, for one conversation is not proof that the next Spotlight window, or ordinary Siri, will follow. Apple’s documented ChatGPT path is still “Ask ChatGPT,” with confirmation controls. Turning those confirms off is a different setting from replacing Siri’s default provider. Voice routing to the example was unverified.

That gap is the story the shipping OS tells on its own. The discovery surface is messy even when the entitlement is forced on: Spotlight, Siri’s separate Ask menu, and System Settings can show different provider lists. Apple’s generic onboarding sheet can mention image generation that the example cannot do. The system is ready to host a guest. It is not ready to treat that guest as the house model.

The Entitlement Apple Has Not Handed Out

Open the gate and Siri becomes a shell other labs can fill. Keep it closed and Apple has a compliance-shaped architecture that still funnels work through its voice, its UI, and its tool list. The September 14 software release did both at once. Siri AI is out in countries where Apple would ship it. The third-party picker is code, not a control.

WHAT WE KNOW

• The hooks: Model Delegation and Inference Provider exist in iOS 27 and macOS Golden Gate and were exercised on camera.
• The current partner: ChatGPT already uses the extension path; the private default IDs still point at it.
• The user setting: There is no public model picker, and Apple has not opened com.apple.developer.model-delegation to other firms.
• The EU split: Siri AI did not ship on EU iPhone or iPad with iOS 27; Apple still has no timeline for those devices.

WHAT IS UNCONFIRMED

• A GPT-5.6 deal: pdfu ran GPT-5.6 Terra through the inference hook; Apple has not confirmed a provider contract.
• A ship date: No public calendar exists for entitlements, a Settings pane, or a true default Ask provider.
• An EU iPhone fix: Trusted System Agent remains a rejected plan, and a later 27.x pairing with EU Siri AI is rumor, not a statement.

Until Apple hands that entitlement to someone other than itself, Claude can think for Siri only on a Mac that has been opened up for development. Everyone else still talks to Siri, and Siri still decides which brain is allowed to answer.